2014 Journal

A A

CALIFORNIA POLYTECHNIC STATE UNIVERSITY CALIFORNIA POLYTECHNIC STATE UNIVERSITY SAN LUIS OBISPO, CALIFORNIA 2013-2014 SAN LUIS OBISPO, CALIFORNIA 2013-2014

A

TAG A

CALIFORNIA POLYTECHNIC STATE UNIVERSITY SAN LUIS OBISPO, CALIFORNIA 2013-2014

Technical Association of the Graphic Arts | California Polytechnic State Univerisity, San Luis Obispo | 2014 Featuring Clickable Paper by Ricoh, learn more on page V

welcome.

On behalf of the California State University, San Luis Obispo student chapter of TAGA, it is my honor to introduce to you the TAGA 2014 Technical Journal. As with past years, we are very proud to showcase a journal that is completely studentproduced from conception to output.

“Learn by doing” is Cal Poly’s motto; working with TAGA has helped create another outlet for students of our field to gain applied knowledge and experience in research, design, production and leadership. Within the past year, our chapter has experienced substantial growth, expanding from an active membership of twelve students last year to over thirty students in this year. We put our attention this year toward improving our internal structure to better utilize team members of varying skill levels.

Our focus within this journal was the blending of traditional print elements with the modern digital medium. With the help of Ricoh’s Clickable Paper technology, we are able bridge the gap between print and digital by simulating how print can be used as a support for a cross-platform, responsive website.

After three years of involvement, I have seen this chapter evolve and improved upon in many ways. We have been able to identify areas of need and address them as a team. Perhaps the greatest asset our chapter possesses is the immense amount of talent, potential and passion that has come from our newer members. As we strive to continue the legacy our university created in 1985, we hope to achieve everything we can today while working diligently toward a greater tomorrow.

Copyright © 2014 California Polytechnic State University, San Luis Obispo, Technical Association of Graphic Arts, Student Chapter

Sincerely,

First Published in the United States of America by Cal Poly TAGA Student Chapter One Grand Avenue San Luis Obispo, CA 93407 Printed at California Polytechnic State University, San Luis Obispo All right reserved. All material in this book has been compiled with the knowledge and prior consent of those concerned, but is published without responsibility for errors or omissions. Nothing in this publication shall be reproduced without the expressed written consent of the authors and editors. Every effort has been made to insure

Sean Garnsey Cal Poly Chapter President

that credits accurately comply with information supplied. We apologize for any inaccuracies that may have occurred.

iv

Bridging the gap with Clickable Paper Step 1: Download the Clickable Paper application by Ricoh Americas Corporation using your device’s application store.

Step 2: Open application and point the camera at any page featuring the symbol below. Then “Click”!

We exist in a world that is in flux.

Our industry is founded upon centuries of printed reproduction, a craft that has been honed and perfected across generations. It has been the cornerstone of commerce, art, free thought, and social change; our culture and civilization has progressed to where it is today with much credit to our ability to disseminate information through the means of print.

Today, print faces the threat of replacement and obselescence to the hands of the digital revolution. Printed publications, forms, advertisement and messages are being replaced at an alarming rate by digital alternatives. This phenomenon and the decline in revenue to traditional print sectors points to an obvious end: irreversible change to our industry.

Step 3: Select an action from the options presented on the device menu.

While some may see this is the end of an era that will be mourned, we must keep everything in perspective. Our industry has always been in flux. We have always faced irreversible change. The digital age has created opportunities within our industry as monumental and comparable to phototypesetting, the linotype machine, and Gutenberg’s press.

Our industry has never been forgiving to those resistant to change. In order to benefit from the digital revolution, we must know how to hop-scotch from our traditional printing roots to a solution that capitalizes on the new dimension digital solutions offer while still playing to the strengths of our trade.

With the help of Ricoh Clickable Paper, we have developed a technical journal and website that transcend the competitive relationship that web and print often has. We hope to demonstrate in simple terms that web and print are collaborative, and that the immediacy of print compliments the dynamism of the web. The key to fostering this relationship is the understanding that the usefulness of this blended platform is governed by the user’s ability to identify what on a printed piece is an interactive enhancement. You will notice symbols throughout this product that you can interact with; print-web interactivity cannot be accomplished without appropriate calls to action to interact.

Please use the instructions to the left to begin interacting with this journal using your mobile device.

www.calpolytaga.com Try it out on this page! v

Visit our website with the clickable paper app

vi

01 23 39 53 69

President’s Message Sean Garnsey

Accurately Reproducing PANTONEÂŽ Colors on Digital Presses Anne Howard

Predicting the Future of Gravure and NFC Technologies

Evaluating the Impression Roller as a Strong Contributor to Gravure Printing Catherine Wang

Electron Beam Curing in the Future of Gravure Printing Julie Famular

Sean Garnsey

The Limits of Gravure in Printed Electronics Galen Tran

iv

INTRODUCTION

02

LITERATURE REVIEW

03

RESEARCH METHODOLOGY

10

RESULTS AND DISCUSSION

12

CONCLUDING REMARKS

15

REFERENCES

17

Abstract

This study investigated how a Xerox DocuColor 2060, Ricoh Pro C900s, and a Konica Minolta bizhub Press C8000 with default settings could print 45 PANTONE ® colors from the Uncoated Solid color book with only the use of cyan, magenta, yellow and black toner. After creating a profile with a GRACoL target sheet, the 45 colors were printed again, measured and compared to the original PANTONE ® Swatch book.

By Anne Howard June 2012

ONDIGITALPRESSES

ACCURATELYREPRODUCING

PANTONE®COLORS

The purpose of this study was to find out how accurately digital presses reproduce PANTONE ® spot colors. The PANTONE ® Matching System is a printing industry standard for spot colors. Because digital printing is becoming more popular, this study was intended to help designers decide on whether they should print PANTONE ® colors on digital presses and expect to see similar colors on paper as they do on a computer monitor.

Results from this study showed that the profile helped correct the DocuColor color output, however, the Konica Minolta and Ricoh color outputs generally produced the same results as they did without the profile. The Konica Minolta and Ricoh have much newer versions of the EFI Fiery RIPs than the DocuColor so they are more likely to interpret PANTONE ® colors the same way as when a profile is used. If printers are using newer presses, they should expect to see consistent color output of PANTONE ® colors with or without profiles when using default settings.

Read Anne Howard’s paper online with any tablet or mobile device!

1

Introduction Statement of the Problem Digital printing is becoming increasingly popular in the printing industry because of its ease of use, low cost of production, and ability to produce short-run jobs. However, some attention should be paid to the process in which raster image processors (RIPs)for digital presses convert colors within print files, particularly PANTONE ® colors, and how well the default (factory settings) of digital presses reproduce those colors. PANTONE® colors, also known as spot colors, are made up of unique pigments instead of cyan, magenta, yellow and black, the four process colors of print. To accurately reproduce a color with toner on a digital press, or any type of press, with the use of solely the four process colors is a difficult task. When a designer has a file they need to have reprinted multiples times, they may bring it to different digital printers with different RIPs. They would expect the colors to look similar, but that does not happen all of the time. This project seeks to examine how accurately three different brands of digital presses with similar versions of raster image processors reproduce a PANTONE ® target test sheet compared to a true PANTONE ® swatch book when all settings are at default.

Raster image processors are what convert files to a language that a digital press will understand in order to print it. When the file has color, the RIP converts that color using its own version of a color lookup table. The problem occurs when RIPs have different versions of the same color that are converted differently, which results in a variation of the original color in the final product. Testing the same target sheet on three calibrated printers with similar RIPs will compare how the PANTONE ® colors are reproduced by the presses.

Also, turning all settings to defaults will help determine how the whole printer’s system for each press produces color. Measurements with spectrophotometer will be taken to verify the color differences on identical paper so an accurate comparison can be made as to which printer and RIP produced the closest version of PANTONE ® colors.

Significance of the Problem The conversion of color by the RIP determines how the color will be printed, along with the internal settings within a printer. The default color settings for RIPs and calibrated presses are set by the manufacturers who determined that with those settings, the machinery is able to produce color accurately with no adjustments.

2

Accurately Reproducing Pantone Colors on Digital Presses

If a digital printer cannot closely reproduce a PANTONE ® color on a digital press, designers may second-guess using the PANTONE ® Matching System, or possibly avoid using digital printing altogether.

If this project can determine the similarities between CMYK and PANTONE ® colors and how closely CMYK can create PANTONE ® when they are printed on the same substrate and run through similar RIPs with default settings, graphic designers may be more willing to use the PANTONE ® Matching System than before.

Interest in the Problem The PANTONE ® Matching System provides standardization for spot color reproduction for print, and when a graphic designer’s work is digitally printed for their customers, accurate colors are expected.

The combination of the growing status and capabilities of digital printing and the use of spot colors have sparked interest in the relationship between the two. Designers use spot colors when CMYK mixtures do not do the job and they expect the color on their computer screen to look the same as the color on a piece of paper.

PANTONE ® colors expand the limits of the printing color gamut and therefore expand printing and designing possibilities. Matching spot colors is an issue in the industry today and this project further explores the limits of how process colors recreate PANTONE ® colors.

Literature Review The PANTONE ® Matching System (PMS) has become the leading color reference system for “selecting, specifying, matching and controlling ink color” in the graphic arts and printing industries (“ PANTONE ®: what we do”). With a forever-expanding variety of specialized colors, PANTONE® has created multiple color systems and guides that all types of designers look to when creating a uniquely colored piece. When much time and effort is put into designing something that includes specific PANTONE ® colors, designers would expect the final printed product to be accurately reproduced. When digitally printed, the file that includes the PANTONE ® colors must go through a RIP that interprets the colors and is then printed with the use of cyan, magenta, yellow and black toner. PANTONE ® offers a variety of color libraries for designers; however, colors may appear differently depending on how they are digitally printed and reproduced, so one can measure the color accuracy to compare back to an original swatch using a spectrophotometer.

Anne Howard

3

PANTONE® Systems & Guides The PMS consists of thousands of unique color mixtures and is separated into different types of categories for specific purposes and usages. There are systems dedicated strictly for the graphic arts, including printing and publishing, clothing, home furnishing and interior decorating, paints and plastics (“ PANTONE ®: what we do”). Because this project aims to compare the accuracy of printed PANTONE® colors from digital printers, this paper will only focus on the systems created for the graphic arts. All of the colors within the PANTONE® Matching System are created by mixing PANTONE®’s fifteen basic colors made from specialized pigments in different amounts (“Solid Color Information”). Those colors include (Table 1): Basic

PANTONE®

Colors

▲ PANTONE® Yellow

▲ PANTONE® Red 032

▲ PANTONE® Purple

▲ PANTONE® Process Blue

▲ PANTONE® Yellow 012

▲ PANTONE® Rubine Red

▲ PANTONE® Violet

▲ PANTONE® Green

▲ PANTONE® Orange 021

▲ PANTONE® Rhodamine Red

▲ PANTONE® Blue 072

▲ PANTONE® Black

▲ PANTONE® Warm Red

PANTONE® Transparent White

▲ PANTONE® Reflex Blue BASIC PANTONE COLORS The fifteen basic Pantone color pigments that are combined in various amounts to make up the PMS.

PANTONE ®

distributes a generalized PANTONE ® Formula Guide, “consisting of 1,114 solid PANTONE ® Colors on coated, uncoated and matte stock [showing] corresponding printing ink formulas for each color, and [a] three-book set of solid chips [that] provides coated, uncoated and matte perforated tear-out chips that can be used for quality control” (“ PANTONE®: what we do”). This particular guide-set would be used for a designer who wanted to recreate a PANTONE ® color using two or more of the 15 basic colors, and then compare the color quality to the original.

Because PANTONE® colors are used for print as well digital material, there is some difficulty making the two versions look alike. To avoid conversion trouble, PANTONE ® has two types of guides with colors that are achievable using the process primary colors of cyan, magenta, yellow and black, or CMYK. They are called the PANTONE® 4-Color Process Guides, a digital guide that includes over 3,000

4

Accurately Reproducing Pantone Colors on Digital Presses

colors capable of being accurately reproduced when printed with the four process colors (“ PANTONE ®: what we do”). The other guide called the PANTONE ® Color Bridge Guide is a coated and uncoated book-set that aims to “compare solid PANTONE ® colors to their closest possible match in CMYK four-color process that can be achieved on a computer monitor, output device or printing press” (“ PANTONE ®: what we do”).

The most recent color guide that PANTONE ® announced in 2007 is called the PANTONE ® Goe System. It “was the first completely new color inspiration and specification system for the graphic arts industry since the introduction of the PANTONE® Matching System in 1962. The System, bringing 2,058 new PANTONE® Colors to market, is comprised of the PANTONE ® GoeGuide, PANTONE ® GoeSticks and my PANTONE ® palettes” (“ PANTONE ® Announces,” 2008). The GoeSticks consists of a two-volume set of color chip stickers that allow designers to put them on their work to view how the color will appear without having to use damaging attachment methods, like glue or staples (“ PANTONE ® Announces,” 2008).

PANTONE® versus CMYK Cyan, magenta, yellow and black, the four process colors of print, are only able to reproduce a limited amount of the visual color gamut (Sharma, 2008). With the use of PANTONE ® inks, the print color gamut is enhanced, represented by the black dots expanding past the pink CMYK limits in Figure 1. The challenge comes when a spot color that appears on screen is out of the limits of the CMYK color gamut, needs to be reproduced for print material using only the four process colors, and the color does not come from the PANTONE ® 4-Color Process Guides. PANTONE® colors look differently on a monitor than on paper because the color gamuts for each are different.

“Computer screens emit color as RGB (red, green, blue) light” (“RGB versus CMYK”). RGB are additive colors, meaning that when the colors are added together on screen, they create a color.

CMYK pigments, on the other hand, are subtractive colors because

Anne Howard

5

they subtract “varying degrees of red, green and blue from white light to produce a selective gamut of spectral colors” (RGB versus CMYK”). Figure 2 shows the differences of how RGB and CMYK combine to create colors.

conversion button that switches the PANTONE ® color value to CMYK values. It also depends on what type of color mode the file is formatted in because it may convert the colors to CMYK when the file is exported as a PDF. When making a file to be printed with any type of color, it is vital that attention be paid to conversion opportunities that may occur throughout the steps from creation to print.

Raster Image Processors

SUBTRACTIVE VS ADDITIVE COLOR RGB, right, creates white light when fully combined and CMY, left, combines to make black.

RGB and CMYK create color differently; one uses additive light and the other uses light wavelength reflection. This makes it more difficult for a color to appear the same in both color spaces.

“In practice, PANTONE ® is favored for solid colors such as those used in logos and letterhead; while CMYK is favored for mixed colors such as those evident in multi-colored photographs” (“Matching PANTONE ®”). The use of PANTONE ® ink allows for a richer color on paper, whether it is on coated, uncoated or matte paper, when compared to a process color version. When the use of PANTONE® inks is too expensive, there are other options for conversion. PANTONE ® offers the 4-Color Process Guides that include the CMYK values for each color (“ PANTONE ®: what we do”). The purpose of this feature is to let graphic designers plug those measurements into their choice of design software to replicate that color to the best of the software’s capability.

In Adobe Illustrator software, there are over ten types of PANTONE ® Swatch Libraries including the most popular PANTONE® solid coated and matte and PANTONE ® process coated and uncoated. To convert a PANTONE ® spot color to four-color process, there is an automated

6

Accurately Reproducing Pantone Colors on Digital Presses

In order for a file to go from digital to print, it must go through a RIP, which then sends the newly translated file to the digital press in a format that the printer can read. “A RIPs basic job is to take vector graphics data and convert it to bitmapped graphics” (Dulis).

When a file is sent to a RIP, it converts the vector data into a raster image, or a bitmapped image, and looks up the colors within the file on a color lookup table for each pixel and then the new highresolution raster image is sent to the printer. Adobe’s Postscript file type is commonly used and generally accepted as a primary printing language in today’s digital printing industry.

Each pixel in the bitmapped image carries information about what colors make it up. The RIP must process them correctly so the printed piece resembles the onscreen file as close as possible.

Electronics for Imaging, Inc., a leading company in the digital technology industry, created the Fiery Digital Print Solution product line that includes RIPs and Fiery Command Workstation, along with many other products (“Overview”). Fiery Command Workstation is a software tool that allows printers to see what files have been ripped, choose each file’s settings and release them to the printer when desired.

Fiery Command Workstation For this project, only toner-based printers using EFI Fiery Rips and Command Workstation 5 to organize and edit their files were selected. “Fiery Command WorkStation is the recognized industry standard for production printing job management technology, serving as the window into the entire printing workflow” (“Downloads,” 2009). It allows printers to edit the colors within the file, color match, create page layouts, select what trays each page is coming from within the printer, adjust page alignment, and other various options for file preparation. According to Frank Mallozzi, senior vice president of worldwide sales and marketing at EFI, this software

Anne Howard

7

is helping printers “gain more productivity from their equipment, reduce errors and waste, and ultimately raise the profitability of each job” (“Downloads,” 2009).

Digital Presses Toner-based digital presses are becoming increasingly more common within printing companies due to its user-friendly operating process.

There is no need for blankets, fountain solution, ink trays or preimaged plates. The general printing procedure for a laser printer, like the ones being used in this project, start with a piece of paper passing by a photoreceptor drum that has either positive or negatively charged areas, which will attract or deflect the toner that is to be transferred to the substrate, constructing the image of the file. A fine powder known as toner acts as the ink for digital presses. It is positively charged so that when the paper passes by the roller, a transfer corona wire negatively charges the paper transferring positively charged toner particles to the substrate in the desired location, creating an image (“Laser Printing,” 2011). This process is repeated for each of the four process colors within the press. The completed image goes through a fuser roller that heats and melts all of the toner to the substrate, finishing the image transferring process.

The toner-based printers being used for this project are a Xerox DocuColor 2060, Ricoh Pro C900s, and a Konica Minolta bizhub Press C8000. The Ricoh and Konica Minolta presses are capable of printing at offset-quality color at 1200 x 1200 dpi resolution and the DocuColor press is only capable of printing at 600 x 600 dpi resolution (“Ricoh Pro C900s”, “bizhub PRESS C8000”, “DocuColor™ 2060”). All three presses have EPI Fiery RIPs along with the same Command Workstation 5 software. The Ricoh has a Fiery System 8 Release 2, the Konica Minolta a Fiery System 9 Release 2 and the DocuColor a Fiery System 3.

Calibration In order for a printer to produce colors that are as accurate and as close to the color on a monitor as possible, it must be calibrated.

That means that the press should be able to reproduce colors in a file correctly if calibrated to the press’s factory calibration settings and standards. Calibration is crucial when trying to reproduce PANTONE ® colors because they are so unique. Writers from Graphic Arts Monthly, Abhay Sharma and Martin Habecost (2008), said: Users of digital printing presses routinely attempt to match output

8

Accurately Reproducing Pantone Colors on Digital Presses

to specified color data. Digital press manufacturers should have a system that can create any desired color on their device-it is important that vendors understand how their toners mix and how to maintain a neutral gray.

Colors shift with digital presses due to an aging press, pressroom temperature shifts, and humidity changes. Quality printer operators should be able to work with their surrounding conditions to keep color consistent between each job. Operators should also use spectrophotometers to adjust the toner amounts being applied according to a target sheet’s data printed from the press to the server to comply with the ICC profiles set in place. ICC stands for International Color Consortium that creates a “standard specification used by color management products. An ICC Profile is a file created to translate the color requests the computer sends to the printer” (Dimov, 2007). Calibration is a necessary step because specific profiles within the serve will dictate how colors are printed.

Spectrophotometers “Graphic arts companies will try everything to meet customers’ color expectations. For many customers, color is the most important criterion to accept or reject a print job” (“Measuring up,” 2008).

Because PANTONE ® colors are so distinctive, a printer’s ability to reproduce them with CMYK toner is difficult. However, a spectrophotometer helps printers print as close to the original PANTONE ® colors while staying within the limits of the visual color gamut.

Spectrophotometers are used to calibrate presses as well as measure and report the spectrum of a print sample. “The spectrum is the most complete descriptor of a color and is a plot of reflectance of [a] sample in all wavelengths from blue to green to red” (Sharma, 2008). This tool measures the reflected light of a color patch and then converts it into CIE L*a*b* values. These values determine how light or dark a color is, their red and green levels and their yellow and blue levels (“Color Difference”). To compare the PANTONE ® target test sheet printed by the DocuColor, Ricoh and Konica Minolta presses and the PANTONE ® swatch book, a spectrophotometer will be used to measure the CIE L*a*b* values and then the difference between the two will be calculated and expressed as a Delta E value. ΔE is “a single number that expresses total color difference which includes: lightness/darkness, redness/greenness, yellowness/ blueness” (“Color Difference”). If the ΔE is lower than 5.0, then to

Anne Howard

9

most observers, the colors will look the same. Whereas if it is higher than 5.0, the digitally printed version will be noticably different than the actual PANTONE ® version. The further away from 5.0 the sample is, the more different it appears when compared back to the reference color. Comparing the test sheets from the three presses to a PANTONE ® swatch book will help determine how similar or differently the colors are reproduced and how close the CMYK versions are to the PANTONE ® swatches.

Research Methodology and Procedures The PANTONE ® Matching System (PMS), a standard for spot colors, is widely used by designers as a means to explore the expanded color gamut that PANTONE ® colors are able to produce. Because some of PANTONE ®’s colors are out of the gamut that CMYK are able to create, it becomes a challenge when the use of the four-process colors is the only option available to reproduce those colors on a digital press. The purpose of this study was to measure and compare how closely the default settings within a printer’s system produce PANTONE ® colors with CMYK toner on digital presses. By using a spectrophotometer to measure the differences between the three PANTONE ® target test sheets compared to a PANTONE ® swatch book, it determined how accurately digital presses, using their default settings, would reproduce PANTONE ® colors.

The experimental research resulted in quantitative data that was used to compare the three digital presses and their outcomes. To test each printer and their RIPs, a PANTONE ® target sheet was created in Adobe Illustrator with a variety of 45 PANTONE ® colors available in the software. The document was in CMYK mode and all of the color swatches that were compared came from the PANTONE ® Solid Uncoated color book within Illustrator. Once the target sheet was created, it was saved as an Adobe PDF with ‘No Color Conversions’ so there are fewer color adjustments between the creation of the document to when the file is printed. This helped better evaluate how each version of the RIPs and printers interpret the PANTONE ® colors. The file was sent to the digital presses through Command Workstation 5, which assists the RIP settings when all of the color conversion settings were at default.

on it or not. From the results and the decision of what paper type to use was made, all of the printer settings were set to default so there are no specialized color conversions when the file was being printed. Along with the PANTONE ® test sheet, a GRACoL target test sheet was printed as well to create profiles on the printers to help get closer readings after the first initial press run.

After the files were sent through the RIPs for the DocuColor 2060, Ricoh Pro C900s, and Konica Minolta C8000, the PANTONE ® test sheet and GRACoL sheet were printed with toner on HP LaserJet 8.5” x 11” paper with 98 brightness that was determined to be closest to the PANTONE ® swatch book. Then, an X-Rite 530 spectrophotometer was used to measure the CIE L*a*b* differences in the readings to determine how closely digital presses are capable of printing PANTONE ® colors with only process color toner and compare them to the swatch book printed by PANTONE ®.

Next, the GRACoL targets were used to create a profile to make color adjustments with software called Profile Maker. Once profiles were created for each press, they were embedded into the Illustrator file for each printer and were saved as PDFs with the Profile Inclusion Policy including all profiles. The PANTONE® test sheets were printed again, the new CIE L*a*b* measurements were recorded again from the spectrophotometer and then compared to the first run and the actual PANTONE ® swatches. The hypothesis was that after using the profiles to adjust the color output, the CIE 1994 (graphic arts) ΔE values for all three presses would be smaller than the values of the colors without the profiles.

Before the target sheets were printed, tests were completed on the PANTONE ® swatch book to find a similar quality substrate to test on. The papers must be alike so the results would be valid. Testing determined the brightness of the paper and if there is a coating

10

Accurately Reproducing Pantone Colors on Digital Presses

Anne Howard

11

The CIE 1994 (graphic arts) Δ E equation (and what each variable means) is the following:

measurements from the X-Rite 530 spectrophotometer were calculated.

PANTONE TEST SHEET 45 Pantone colors used to measure and test three digital printers.

After the profiles were created and embedded into the PDFs, the test sheet was printed again and those numbers were recorded as well. Then using the CIE L*a*b* measurements, the ΔE94 values calculation were used to find the differences between the print samples and the reference swatch colors.

The results would show which of the three presses had the most improvement and which one got the closest to the original swatches and stretched the limits of toner producing PANTONE ® colors out of the CMYK color gamut using the default settings of the printers.

As mentioned previously, a ΔE value higher than 5.0 will yield visibly different colors, while a value lower than 5.0 will not.

The averages for each ΔE94 value per printer are listed in table 2 below:

Results and Discussion The purpose of this study was to determine how closely cyan, magenta, yellow and black toner could reproduce PANTONE ® colors on digital presses and if the use of a GRACoL profile would help make improvements. After printing the 45 PANTONE ® colors (figure 3) without a profile, the ΔE94 values for the DocuColor, Ricoh, and Konica Minolta color outputs using the CIE L*a*b*

12

Accurately Reproducing Pantone Colors on Digital Presses

Average

Konica Minolta w/o Profile

Konica Ricoh Minolta w/o w/Profile Profile

Ricoh w/ DocuProfile Color w/o Profile

DocuColor w/ Profile

5.23

5.23

11.46

6.79

11.41

10.35

COLOR PROFILES ∆E94 averages of all three printers with and without the use of a color profile.

Anne Howard

13

The Konica Minolta C8000 press had the exact same average of 5.23 with and without the use of a color profile. This printer has an internal image controller called an IC-601. “It offers various highly functional features including high-speed RIP processing, enhanced color image reproduction, [and] high speed image transfers” (“Konica Minolta”). Because it has this internal color management system, colors printed were interpreted the same way, resulting in the same ΔE94 value average. The colors that the Konica Minolta had the most difficulty matching to the original PANTONE® swatches without a profile were 324 U, 421 U, and 7547 U. After the profile was embedded, the colors with the highest ΔE94 values were 324 U still, 1375 U, and 1225 U. The DocuColor 2060 was the only printer that was positively affected by the use of the color profile. With a ΔE94 value drop of 3.60, all of the PANTONE ® colors were still noticeably different than the PANTONE® Swatch book. This press is about 13 years old, whereas the Konica Minolta and Ricoh are only a couple of years old, so its RIP does not have the same type of color management system that is capable of interpreting the PANTONE® colors as accurately without a color correcting profile. However, the DocuColor did produce the smallest ΔE94 value for any color, with or without a profile, than either of the other printers. The ΔE94 value for 2707 U was only 1.61 without the use of a profile. It also had the biggest improvement by the profile for 209 U from 21.26 without the profile to 2.72 with the profile. The colors that the DocuColor had the most difficulty matching without a profile were 209 U, 269 U, and 3308 U. After the profile was embedded, the colors with the highest ΔE94 values were 2715 U, Green U, and 324 U. The Ricoh Pro C900s had about the same ΔE94 value average with and without the color profile with a difference of only 0.05. That meant that the color management system within the EFI Fiery RIP was generally reproducing the same way as it did with the GRACoL profile. The RIP interpreted the colors as accurately as it could for both print runs. The colors that the Ricoh had the most difficulty matching without a profile were 2715 U, 410 U, and 424 U. After the profile was embedded, the colors with the highest ΔE94 values were 2715 U and 410 U again, along with 7533 U.

14

Accurately Reproducing Pantone Colors on Digital Presses

Overall, only the Konica Minolta C8000 press averaged just above the point in which the color difference of the test sheet and PANTONE ® swatch became noticeable at 5.23. That showed that with simple default settings, these digital presses, with only the use of process color toners, generally were unable to create PANTONE ® colors from the Uncoated Solid color book. Only the DocuColor 2060 increased its color accuracy with the GRACoL profile, disproving the hypothesis that all of the printers will improve after a profile was embedded into each of the PANTONE ® test sheet PDFs.

Concluding Remarks The PANTONE ® Matching System was created so graphic designers, along with packaging designers and interior designers, were not limited to only what CMYK inks could physically produce. With thousands of colors to choose from, PANTONE ® expanded the color gamut for print and digital material because these spot colors were specially developed from the fourteen basic PANTONE® colors and pigments, as opposed to the four process colors, which have restricted combination abilities.

Combine the current popularity of PMS colors with the increasing prevalence of digital presses in print companies and there will be a greater need for color accuracy and press customization. As evidenced in this study, a Xerox DocuColor 2060, Ricoh Pro C900s, and a Konica Minolta bizhub Press C8000 had difficulty producing PANTONE ® colors with ΔE94 values at 5.0 or under using all default settings, even with the help of a GRACoL color correcting profile.

With the embedded profile in the PANTONE ® test sheet PDF, the DocuColor printed some of the 45 PANTONE ® colors more closely to the actual PANTONE ® swatches, but most were still visibly different.

The Konica Minolta had the lowest average of the ΔE94 values from both rounds of printing that did not change, because it has an internal color management system that could interpret the colors as accurately as possible under the testing conditions with and without a profile.

The Ricoh also did not improve from the first print run to the second because it has a RIP that also interpreted the colors as best it could with default settings. Ultimately, digital presses struggle reproducing spot colors with CMYK because those colors were not meant to be printed with process toners. However, with color correction profiles and customized printer settings, it is possible to improve spot color output.

A

A human error had been made when measuring the CIE L*a*b* numbers for PANTONE ® colors 250 U and 3935 U so their ΔE94 values were not included into the averages of each press.

Anne Howard

15

References Color Difference Matters. (n.d.). Retrieved from https://www.sabicip.com/staticcxp/ user/en/LearnAboutColor/ColorBasicsDetail/color_diff_measurement.html.

Dimov, C. (2007, October 28). Spectrophotometer – frill or norm?. Retrieved from http://graphicartsmag.com/articles/2007/10/spectrophotometer—frill-or-norm.

DocuColor™ 2060. (n.d.). Retrieved from http://www.xerox.com/digital-printing/ printers/digitalpress/docucolor-2060/spec-enus.html.

Dulis, P. (2003, 20 July). To RIP or not to RIP. Retrieved from http://graphicartsmag. com/articles/2003/07/to-rip-or-not-to-rip.

Downloads exceed 10,000 in first three months for latest Fiery Command Workstation software. (2009, August 5).

Business Wire. Retrieved February 18, 2012, from ProQuest Newsstand.Konica Minolta Bizhub PRESS C8000. (2011, January). Retrieved from http://www. konicaminolta.com.au/library/BERTL_C8000_5-Star_Test_Report.pdf.

Laser Printing Process. (2011, March 8). Retrieved from http://ciscoskills. net/2011/03/08/laserprinting-process/.

Lindbloom, B. (n.d.). Color Difference Calculator. Retrieved from http://www. brucelindbloom.com/index.html?ColorDifferenceCalc.html.

Matching PANTONE® to CMYK color. (n.d.). Retrieved from http://www.psprint. com/resources/printing-tips-and-techniques/general/matchingPANTONE®-cmykcolor.asp.

Measuring Up. (2008, December 1). Retrieved fromhttp://americanprinter.com/ workflow/measuring-up-1208/).

PANTONE® announces uncoated version of new PANTONE® Goe System. (2008, May 29). Retrieved from ProQuest Newsstand, ProQuest.

PANTONE®: What we do. (n.d.). Retrieved from http://www.PANTONE®.com/ pages/PANTONE®/PANTONE®.aspx?pg=19295.

RGB versus CMYK. (n.d.). Retrieved from http://www.printernational.org/rgbversus-cmyk.php.

RGB versus CMYK. (n.d.). [Figure 2]. Retrieved from http://www.printernational. org/rgb-versuscmyk.php.

Sharma, A. (2008). Color management for packaging: Spectral colors & beyond.

Retrieved from http://www.flexoglobal.com/flexomag/08-May/flexomag-sharma.htm.

Sharma, A. & Habecost, M. (2008, May). Digital presses: See how they run. Graphic Arts Monthly, 80(5), 64. Retrieved February 18, 2012, from ABI/INFORM Global.

Solid Color Information. (n.d.). Retrieved from http://www.PANTONE®.com/pages/ PANTONE®/PANTONE®.aspx?pg=20459&ca=1.

16

Accurately Reproducing Pantone Colors on Digital Presses

Anne Howard

17

Author’s Bio Anne Howard Anne graduated from Cal Poly in 2012 with a degree in Graphic Communication, a concentration in Graphics for Packaging, and a minor in Packaging. While at Cal Poly, Anne was a member of Mat Pica Pi and was in Student Community Services for two years.

She worked with Poly Paws organizing volunteer opportunities for students to help homeless animals in San Luis Obispo. Since graduating, Anne has found a new love for running and recently finished her first marathon in San Francisco. Anne currently works at a digital printing company in Elk Grove, CA.

18

24

ANALYSIS

25

CONCLUDING REMARKS

32

REFERENCES

33

Abstract

By Galen Tran June 2012

PRIN TED ELEC T RONICS

THE LIMITSOFGRAVUREIN

INTRODUCTION

Gravure has been making pushes in recent years to make its way into printed electronics. Gravure has advantages in making printed electronics because it has many characteristics that make it a viable option for printed electronics. Unfortunately, gravure has a problem with fine lines and rules, which makes it hard for finer details in transistors when printing the electronics. On the flip side, gravure is a great process for creating the semi-conductors and dielectrics.

Read Galen Tran’s paper online with any tablet or mobile device!

23

would mean that every piece is added on, with zero excess that goes to waste (Sung, 2010). Printing electronics ultimately means saving money. The idea behind printing electronics is to try an alladditive production of electronics versus the traditional production of electronics (Molesa, 2006).

Analysis Print Consistency

PRINTED ELECTRONICS The ability to print circuit boards are giving headway into printed electronics.

Introduction

Gravure makes a great printing process for quite a few reasons. It has the capability of consistent printing and uses engraving to create the image area. This allows for the process to have longer run lengths, meaning precision is kept after many runs. Compare this to offset lithography. Lithography can create faster plates, but the plates do not last as long. This generates a less consistent print, and in turn a less consistent semiconductor (Ring Oscillator, Huebler, 2007).

Gravure has been rapidly pushing its way into the printed electronics market. Gravure has various qualities that make it ideal for printed electronics, but it also has some downfalls. It excels on high throughput, meaning high productivity, but it sorely lacks in fine details. This paper will go over gravure printing’s strengths and weaknesses when it comes to producing printed electronics.

In order to figure out the usefulness of gravure as a process to make printed electronics, many secondary research sources were used. There were quite a few sources that delved into the idea of using gravure to make a certain aspect of printed electronics. These secondary sources are usually in the form of lab experiments that show the different printing processes and their performance in printing a certain part of a full circuit. Oddly enough, no source actually compiled all the capabilities of gravure to print the parts for a full circuit.

Why print electronics?

Gravure is an excellent process to consider because of its versatility in printing on different substrates. It also has the ability to print in a web, which means that it can be seamless and have a constant print. This would be beneficial for such printed electronics as solar panels. Printing in general is an additive process and means that there is less waste. Traditional means of manufacturing silicon circuits are a subtractive process. Usually silicon is cut into chips and from there is cut away to form the circuit. Printing the circuit

24

The Limits of Gravure in Printed Electronics

PRINTING CIRCUIT BOARDS Gravure has the capability of consistent printing.

Print consistency is a key issue particularly with electronics, as every fine detail needs to be precise. A semiconductor is a material that is both a conductor and an insulator. This special property allows certain electrical properties through, while insulating others. The semiconductor layer needs to have a consistent laydown method

Galen Tran

25

because any impurities or variables can alter the semiconductor’s conductivity (Basics of Semiconductors, n.d.). This being said, gravure is known to be able to deliver high quality layers and handle low viscosity inks. While offset is another high quality printing process and can create finer lines than gravure, offset is severely limited by the range of substrates that it can print on. Gravure excels in being able to print on a large variety of substrates. Flexography can also print on a large variety of substrates, and is widely used for publications and packaging, much like gravure. Unfortunately, flexography has an issue with halos, which gets in the way of circuits and small details when creating a semiconductor layer (Sung, 2010).

Dielectrics Gravure is also good at making the dielectric layer of an electronic.

A dielectric is an insulator to a capacitor and helps increase the capacitance of the capacitor. Dielectrics are also meant to prevent any conductive strips from coming into contact with each other.

Dielectrics prevent sparks from occuring when too much voltage runs through the conductive material it is insulating (Dielectrics, n.d.).

According to Nikolav Vakley from the Imperial College London, “Gravure is a viable fabrication technique for microelectronics applications, and it can deliver electronic-grade dielectric coatings that approach state-of-the-art.” This was concluding an experiment regarding printing a dielectric in comparison to creating one through traditional means. Gravure was actually shown to be able to produce a dielectric that had a similar performance and thickness as traditional means.

Printing Fine Lines So far, gravure has proven itself to be able to print two major components of any electronic. The one last thing that it needs to make a full printed electronic is the conductive material. This is where gravure falls short. Due to the nature of gravure, (having engraved cells instead of dots) printing the fine lines of circuits is where gravure has trouble. This can be seen quite plainly, whenever gravure prints text or rules. If closely observing such text and rules, you can see the jagged lines formed by the ink cells. This presents a problem when trying to print the thin conductive strips that circuits need (Ring Oscillator, Huebler. 2007).

26

The Limits of Gravure in Printed Electronics

HIGH CONDUCTIVITY Nanoparticle inks have been used because they form smooth, high conductive lines when printed.

Scaling Gravure Fortunately, there have been measures taken to further improve gravure’s scalability. Nanoparticle inks have been used recently because they form smooth, high conductive lines when printed.

Viscosity plays a big role in the resulting quality of the dots.

In general, the higher the viscosity, the thicker the printed dot.

However, if viscosity is too high, then the cell may fail to deliver the dot to the substrate because it will get trapped inside the cell.

Viscosity of the ink has been found to have a very minimal role in the width of the printed dot (Sung, 2010).

On a similar note, gravure also has the ability to be scaled down.

In a secondary lab experiment to test the scalability of gravure, the researchers conducted tests using a scaled version of an industry gravure press. The laboratory press was 2.62 inches in diameter, whereas industry presses tend to be 4-40 inches in diameter (Sung, 2010).The scaled press was designed to go more in depth when printing thin-film transistors using gravure-printed nanoparticle lines. They found that gravure has the potential to be scaled and work at smaller scales than industry has seen. Gravure makes a good candidate for printed electronics because its nanoparticle-printed lines are smooth and have a high conductivity (Sung, 2010).

Roll-to-roll gravure has also been experimented with, as to how scalable the process is. It is one of the leaders in making a low-cost,

Galen Tran

27

high production printed electronic process, but is limited due to overlay print registration accuracy. In a secondary experiment, tests were conducted to determine what factors could help produce better overlay print registration accuracy. Key points of the test were observing connectivity of the transistors, thickness of the lines, line widening and surface roughness. In general, the main variable that really affected those key points in a positive manner was running the press at a faster speed. Another aspect that had a large impact on the overlay print registration accuracy was the ink viscosity.

Unfortunately with viscosity, even though higher ink viscosity helped connectivity, line thickness, and line widening, it negatively affected surface roughness (Noh, 2010).

Gravure Throughput Gravure has consistent printing and better productivity when compared to other printing processes that have been used to try and print electronics, namely inkjet. Not only does gravure have better throughput, it is known for its long run lengths before having to change the cylinder. This could call for cheaper units once the cylinder has been engraved.

This would be a main factor in choosing gravure over offset, because once the cylinder has been engraved, gravure can continue to run without having to change p l a t e s ( Mo l e s a , 2 0 0 6 ) .

However, this is a doubleedged sword because gravure does have a long process time to make the cylinder in the first place. This fact alone makes gravure have a heavy initial capital cost versus offset and inkjet. However, one thing that makes gravure really stand out is how simple the printing process is. This ensures there are fewer variables in the printing process, which is crucial in how accurate the process needs to be for circuitry (Noh, 2010).

28

The Limits of Gravure in Printed Electronics

Gravure has the potential to do roll-to-roll printing (printing on a roll of plastic or metal foil as a substrate), which has high productivity. By having a web of substrate, rather than a sheet, there can also be faster runs. This goes hand in hand with the durability of the gravure cylinder. Once the press is up and running, gravure has a very high production rate because it does not have to stop. The other printing process that functions well with webs is web offset.

However, gravure is more viable because the cylinder is seamless so it forgoes having a gap to hold the plate that web offset has. Gravure can also create high quality uniform prints that are defect-free, which is essential for micro printing (Noh, 2010).

As of now, gravure has the most promise for printed electronic technology. This is because gravure inks are the most homogenous and one of the lowest viscosities. Gravure has already broken into the printed electronic market. For example, it is already being used to print out solar cells, and has been proven to be capable of printing dielectrics and semiconductors, both major components of a circuit.

Gravure can print the smallest dielectric thickness, compared to other printing processes such as flexography and offset printing.

Gravure is also a good process because the chrome plating on the cylinder make it more resistant to solvents. As stated before, gravure is capable of printing roll-to-roll. In this specific study, gravure was able to print 50,000 transistors on a single roll. Out of the amount of printed transistors, about 75% were functional (Hambsch, 2010).

This is a major breakthrough in printed electronic technology, because gravure is showing that it is becoming more and more capable of printing working electronics one piece at a time.

Shortcomings of Gravure Printing Unfortunately, gravure still has a lot of room to improve. One of the biggest downfalls that were glanced over is the amount of time it takes to engrave a cylinder and the engraving process in general. Unlike other processes like inkjet, which is more flexible in alignment because ink is deposited in small drops. Gravure on the other hand has a more intensive alignment process because the whole cylinder needs to be engraved. When gravure prints, the whole cylinder needs to be aligned in order to print correctly on a substrate. This becomes the most problematic when printing patterns, especially a pattern that is only microns thick. This is escalated to be a bigger problem because of how big and heavy the gravure cylinders are. Not only that, but the alignment can still be off because of the flexible substrates that can distort (Molesa, 2006).

Galen Tran

29

Disadvantages of Engraving Another disadvantage that engraved cylinders have, as opposed to processes like inkjet, is how permanent it is. Once engraved, the gravure cylinder is stuck in that form until the copper and chrome is stripped. Inkjet, on the contrary, is a digital process so it can change patterns based on commands from the computer.

Gravure cannot do this so simply; it must be stripped and then the roller needs to be copper plated, engraved, and then chrome engraved. That is a lot of time that is wasted, just to fix a pattern that was not desirable. That much processing also means that the initial cost of printing will be higher than other printing processes.

However, this disadvantage is also one of gravure’s redeeming factors. Since each cell is carefully measured out and does not deviate that much, the ink deposition is a lot more precise and controlled as opposed to other printing processes (Molesa, 2006).

Fine Line Problems Gravure also has a very hard time printing fine details. As mentioned before, because of the nature of cells, gravure cannot print rules without jagged edges. Although there are new methods that are coming out such as laser engraving, the process as it stands now has jagged edges. The other limiting factor in regards to fine detail is seen in the inks that are necessary for printed electronics.

Nanoparticle ink has too low viscosity for gravure. Although it can be used, the viscosity can either cause the printed dots to smear or have trouble fully coming out of the cell altogether. Inkjet has no trouble with the low viscosity of nanoparticle ink, because in general inkjet ink has a lower viscosity that that of gravure (Molesa, 2006).

Speaking of fine detail, alignment is a big factor when it comes to printing gravure. The small details make it very hard to align the large cylinder. Not only that, but printing on flexible substrates makes it hard. Many variables affect the substrate. Heat can easily distort the cylinder and throw off the alignment. Not only that, but the bearings holding the cylinder can shift slightly and ultimately ruin the alignment of the cylinder to the substrate. To add to the

30

The Limits of Gravure in Printed Electronics

variables, the flexible substrate has a common known problem to distort due to prolonged exposure to heat (Molesa, 2006).

Hybrid Printing There is a silver lining (not to be confused with printing silver lines in transistors); there have been movements in trying to expand into hybrid printing to make printed electronics. One of the major ideas is to mix inkjet with gravure. Gravure is very good at making dielectrics and the semiconductors. This is due to its consistency and its ability to do roll-to-roll printing. Gravure is good making long sheets, and dielectrics and semiconductors can be created in long sheets and cut after (Hambsch, 2006). In general, a lot of large area components such as capacitors, inductors, and anything that does not require precise alignment can benefit from gravure. After that, inkjet can be used to print the finer lines, because it handles nanoparticle inks much better than gravure. Not only that, but inkjet is also better at producing fine lines and rules in general since it is a completely additive process. Fine lines can be aligned better because inkjet is controlled digitally and micro adjustments can be made on the computer to align the printer with the substrate. So printing components such as transistors, where alignment is crucial, can utilize inkjet (Molesa, 2006).

Using Inkjet Gravure by itself is great for its throughput, but its disadvantages do not make it ideal for low cost production of printed electronics.

Making a mix of gravure and inkjet is beneficial because it takes gravure’s strength in throughput and does not diminish it with inkjet’s lack of throughput, since the transistors would not take more than 50 drops of ink from inkjet. Using inkjet would also mean that alignment could be done on the job, as it needs it, because inkjet can align easier than other processes since it is completely digital.

Inkjet is also comparable to gravure in its ink droplet volume, so the use of expensive materials, such as silver for the transistor lines, can be cut to a minimum. This ultimately saves money and creates cheaper electronics at a possibly faster production rate than traditional means (Molesa, 2006).

Using Flexography The other hybrid model that is being considered is mixing gravure and flexography. What makes them possible options for hybrid printing is that they both have very high production volumes. The idea of

Galen Tran

31

printed electronics is to try and lower the cost as much as possible, so naturally looking at the highest throughput printing processes is natural. Similar to the inkjet and gravure hybrid, gravure still makes a good choice to print the semiconductors and the dielectrics, because of its good throughput at making long seamless images.

However, the difference is flexography can be used to make the transistors and the gate electrodes, to complete the circuit. Flexography is printed using a lot of pressure though, so pressure needs to be adjusted accordingly in order not to ruin the fine lines, or crush the transistors. Unfortunately, the performance of the circuits that were printed via this method was subpar. The circuits made by this process were a lot slower at sending a frequency than expected. However, this shows that making a printed electronic, purely using printed means is feasible and can possibly be mastered and refined in a very near future (Three-dimensional, Huebler, 2011).

Concluding Remarks As has been shown, gravure shows a lot of promise in the printed electronic industry. It really shines in how precise it lays down ink and its throughput. Gravure is a great process for making semiconductors and dielectrics, because it can print seamless images and also has the capability to print roll-to-roll. Even though gravure does fall short when it comes to making fine lines, there are measures being taken to improve the precision of gravure. One of the main breakthroughs is scaling gravure down in order to make it capable of printing the fine silver lines for transistors. There are also hybridprinting options. Some of the more viable options include mixing flexography and inkjet with gravure. Overall, gravure really follows the idea of making printed electronics a low-cost alternative to traditional means because of its production speeds. If this is mixed with the other printing methods to cover its downfalls until gravure improves in those areas, printed electronics could be a realistic possibility in the near future.

References “Basics of Semiconductors.” Basics of Semiconductors. N.p., n.d. Web. 03 Mar. 2013. <http://enpub.fulton.asu.edu/widebandgap/NewPages/SCbasics.html>.

“Dielectrics.” The Physics Hypertextbook. The Physics Hypertextbook, n.d. Web. 05 Mar. 2013. <http://physics.info/dielectrics/>.

Hambsch, M., K. Reuter, and M. Stanel. “Uniformity of Fully Gravure Printed Organic Field-effect Transistors.” Materials Science and Engineering 170.1-3 (2010): 93-98. Science Direct. June 2010. Web. 1 Feb. 2013. <http://www.sciencedirect. com/science/article/pii/S0921510710001443>.

Huebler, A. C., and F. Doetz. “Ring Oscillator Fabricated Completely by Means of Mass-printing Technologies.” Organic Electronics 8.5 (2007): 480-86. Science Direct. Oct. 2007. Web. 1 Feb. 2013. <http://www.sciencedirect.com/science/article/ pii/S1566119907000365>.

Huebler, A. C., G. C. Schmidt, and H. Kempa. “Three-dimensional Integrated Circuit Using Printed Electronics.” Organic Electronics 12.3 (2011): 419-23. Science Direct. Mar. 2011. Web. 1 Feb. 2013. <http://www.sciencedirect.com/science/article/ pii/S1566119910004088>.

Molesa, Steven E. Ultra-Low-Cost Printed Electronics. Tech. no. UCB/EECS-200655. University of California, Berkley, 15 May 2006. Web. 2 Feb. 2013. <http://www. eecs.berkeley.edu/Pubs/TechRpts/2006/EECS-2006-55.pdf>.

Noh, Jinsoo, Dongsun Yeom, Chaemin Lim, Hwajin Cha, Jukyung Han, Junseok Kim, and Yongsu Park. “Scalability of Roll-to-Roll Gravure-Printed Electrodes on Plastic Foils.” IEEExplore 33.4 (2010): n. pag. Oct. 2010. Web. 1 Feb. 2013. <http:// ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5551262&tag=1>.

Sung, Donovan, Alejandro Vornbrock, and Vivek Subramanian. «Scaling and Optimization of Gravure-Printed Silver Nanoparticle Lines for Printed Electronics.»

IEEE 33.1 (2010): n. pag. IEEExplore. Mar. 2010. Web. 1 Feb. 2013. <http:// ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5350800&tag=1>.

Yan, He, Zhihua Chen, Yan Zheng, Christopher Newman, Jordan R. Quinn, Florian Dotz, Marcel Kaslter, and Antonio Facchetti. “A High-mobility Electron-transporting Polymer for Printed Transistors.” Nature International Weekly Journal of Science (2009): 679-86. 21 Jan. 2009. Web. 1 Feb. 2013. <http://www.nature.com/nature/ journal/v457/n7230/full/nature07727.html>.

Vaklev, Nikolay. “Printable, organic and large-area realisation of integrated circuits.” Polaric. 18 April, 2012. Web. 1 Feb. 2013. <http://ec.europa.eu/ information_society/apps/projects/logos/8/247978/080/deliverables/002_ D33OTFTswithgravureprinteddielectricPUBLIC.pdf>

A

32

The Limits of Gravure in Printed Electronics

Galen Tran

33

Authorâ&#x20AC;&#x2122;s Bio Galen Tran Galen Tran is a 4th year studying in Graphic Communication, Graphics for Packaging. He enjoys printing on the web offset press and does film work on the side. He is also creating a clothing line for his senior project.

Watch Galenâ&#x20AC;&#x2122;s exclusive author interview online! Can you guess his spirit animal?

34

40

HYPOTHESIS

42

RESEARCH METHODOLOGY

42

RESULTS AND DISCUSSION

46

CONCLUDING REMARKS

46

REFERENCES

47

Abstract

By Sean Garnsey November 2013

GRAVURE & NFC TECHNOLOGY

PREDICTINGTHEFUTURE OF

INTRODUCTION

Gravure Technology has been thrust into the spotlight in the world of printed electronics. Gravure printing characteristics will make it easier to produce electronics, especially Near Field Communication tags. This paper explores the feasibility of producing Near-Field Communication chips using gravure printing and the effect it could have on the mobile device market. Included is secondary research from recent studies in the field of gravure printed electronics and a research interview with Mr. Frank Romano from the Rochester Institute of Technology. The findings were positive in that while we have not reached the point where we can produce sophisticated NFC tags in their entirety, it is well within our reach.

Read Sean Garnseyâ&#x20AC;&#x2122;s paper online with any tablet or mobile device!

39

Introduction The mobile device industry is entering a new era as tablet and smartphone computing is simultaneously becoming more capable and affordable. This September, Samsung launched an ad campaign aimed directly at Apple’s iPhone 5 (Gilbert, 2012). This ad featured the Galaxy S3’s Android Beam, which uses a type of communication technique called Near-Field Communication (NFC). The campaign slogan, “The next big thing is already here,” implies that the GS3’s use of NFC technology has positioned Samsung to change the landscape of the mobile market forever. This research paper will evaluate the feasibility of using gravure printing technology to proliferate the use of NFC tags as well as predict the impact of NFC technology on the mobile device market.

Near-Field Communication Near-Field Communication, as opposed to WiFi or Bluetooth, is a communication technology that utilizes the electromagnetic radio fields instead of radio transmission to exchange data (NearFieldCommunication.org, n.d.). NFC is an offshoot of Radio Frequency Identification (RFID) that expands upon the abilities of the original RFID technology. By their nature, NFC & RFID each consume minimal amounts of energy for data transfer.

Unlike RFID, however, NFC allows for two way communication, meaning that data can be transferred to and from the receiver.

RFID has become predominantly used with chips known as “tags”; the limitation in RFID lies in the fact that the tags allow for oneway communication (Chandler, n.d.). NFC technology allows mobile devices to communicate with tags and with other devices, consequently expanding the technology’s potential uses.

NFC Tags

NFC TAGS RFID, NFC tags are chips that allow for interaction with devices.

40

Like RFID, NFC tags are chips that allow for interaction with devices.

Both RFID and NFC chips use a process called Electromagnetic Induction. Electromagnetic Induction uses electromagnetic energy from a transmitting source and converts that energy into electricity. That energy is then converted into a radio wave signal, delivering data back to the energy source (Bonsor, n.d.). Electromagnetic

Prediciting the Future of Gravure & NFC Technology

Induction can be attributed to the low energy-consumption of RFID and NFC technology. NFC chips can be read and written by other devices just like RFIDs. An advantage that RFID has over NFC is range, NFC is only effective at around up to 10 inches from the chip itself while RFID can be read from a few feet away.

NFC’s close range is one of its strengths. In addition to being readable and writeable, NFC chips can store and emulate credit cards securely, as well as allow for fast device-pairing.

Gravure Printing Technology Rotogravure printing, gravure for short, is an intaglio process that has been gaining attention in the printed electronics industry. Gravure is known for its capability to print long-runs as well as superior color reproduction. Gravure has been identified as a frontrunner in printed electronics for its “advantage over other printing processes in that it can change ink film thickness. By altering the cell depth ink film thickness can be changed and that plays a major role in deciding resistivity” (Sung, n.d.). It is undisputed that the use of printing processes will dramatically improve the cost and efficiency of producing electronic components.

Where is NFC now?

NFC technology is currently on the rise. Android Beam is a software developed for all post-Ice Cream Sandwich Android applications that allows for the phone to interact with NFC tags. Unfortunately, Apple does not currently have the technology to enable its phone to use NFC technology. NFC tags are currently produced by etching the circuitry out of copper or aluminum film (Park, n.d.). This process takes considerable effort and involves a lot of waste, resulting in a premium price for NFC tags. NFC may not flourish as a technology until the cost is lowered enough to proliferate its usage.

The Vision for NFC Technology The mobile device industry, primarily with companies that support the Android operating system, hope to use near-field communication to create an interactive environment unlike any other. Not only will NFC tags be used to read and write information like an RFID tag or QR code, but there will be huge advances in peer-to-peer interactions. NFC enables contactless payment, instant internet connection, high-speed data transfer and the ability to allow a friend to be brought into an app or game without having to download that

Sean Garnsey

41

app (Chandler, n.d.). A wall will be broken down when it comes to marketing products to consumers-- imagine walking up to a movie poster, placing your phone against it and being able to instantly view the trailer for that movie. Perhaps you might find yourself walking through the grocery store comparing pre-packaged health food dinners. Today you may have to take out those individual packages and read the nutrition facts separately to make your decision, but in the future NFC would enable you to quickly scan the foods you are interested in and compare prices, nutrition facts and serving sizes and help decide what is best for you based on your preferences.

NFC will be the deciding factor in the push for wide-spread usage of smart-devices. After NFC becomes widespread it will enable so much practical usage for mobile devices that smart phones and tablets will no longer be viewed as luxury items but instead a common tool utilized by everyone.

Hypothesis Gravure is an ideal process because it is a simple yet effective longrun print technology that can print high-resolution images quickly and reliably.

Advantages of gravure in printed electronics: ► ► Can print continuous flow of dots, unlike inkjet ► ► Suitable for large-run capabilities ► ► Better ink properties than that of a web-offset press Limitations to gravure in printed electronics: ► ► Resolution must be very fine.

PRINT COMPLEXITY Printed electronics pose a new dimension of complexity that print production has never previously encountered.

► ► The fewer the layers the easier the product is to produce. ► ► The proliferation of NFC technology is heavily dependent on gravure technology overcoming physical limitations regarding resolution, substrate and ink properties.

Research Methodology Predicting the future of NFC technology requires both realism

42

Prediciting the Future of Gravure & NFC Technology

and imagination. Printed electronics pose a new dimension of complexity that print production has never previously encountered.

Traditionally, inks are generally evaluated for their visual and tactile properties; with printed electronics, we must evaluate conductivity & resistance, ink film thickness and flexibility to gauge whether we can produce a specific product.

Production of NFC Rectennas One of the vital parts to the NFC tag is a component known as a rectifier and antenna, or rectenna, where “an antenna inductively couples AC at 13.56 MHz and then the rectifier converts coupled AC to DC power” (Park, n.d.). It is found that traditional etched rectennas are very effective but are costly to produce. Rectenna production has faced three major limitations: ► ► Resistance - Gravure ink thickness is usually no greater than 1 µm, this substantially increases the resistance in the circuit.

This makes it more difficult to produce a greater Q factor which is vital for creating a successful rectenna. “The Q factor is a measure of the coupled voltage and current of the resonance circuit at the resonance” (Park). ► ► Shorting - Printed rectennas have faced issues with a lack of high dielectric ink that prevents capacitors from shorting. ► ► High-Frequency applications - There was previously a lack of inks that are suitable for high-frequency applications.

These have all been overcome in recent testing through producing inks that have greater conductive properties.

Gravure Output Gravure will have little difficulty dealing with properly engineered inks.

Gravure is “capable of printing a relatively wide variety of ink viscosities, or thicknesses of ink.

Tr a d i t i o n a l g r a v u r e printing yields excellent q u a l i t y, a n d m i c ro engraving and microgravure printing are

GRAVURE CELL PATTERNS Gravure printing yields excellent quality and micro-engraving and micro-gravure printing are capable of an extremely high resolution, or very detailed product, necessary for high desnity ciructs.

Sean Garnsey

43

capable of an extremely high resolution, or very detailed product, necessary for high density circuits” (Clark, n.d.) An issue that gravure does run into is in producing consistent ink lines. The solution that some have found is by etching trenches into the gravure cylinder instead of cells. “They remove the need of optimizing drop spacing and drop radius and can theoretically be scaled down to very small cell widths without worrying about cell emptying” (Clark, n.d.). The downside to using trenches, however, is that ink printed in the circumferential direction often times will never leave the cell itself. Ultimately, it will come down to whether the substrate and ink would be more suitably used with trenches or cells themselves and we may see a combination of the two in the future.

Industry Opinion As a part of my research I conducted an interview with the famed Graphic Communication guru and expert on future business trends in the industry, Dr. Frank Romano. Dr. Romano asserted that the question is not “if ” NFC tags and technology will become printable, but instead “when”. NFC technology is now 8 years old, which is still very new by any technology’s standards. Dr. Romano warned that in order for a technology to experience true success, it must not be implemented too early or too late.

While not allowed to disclose what the particular electronic product is or which company is producing it, Dr. Romano hinted that many types of printed electronic products are actually being researched and manufactured covertly. He has had the opportunity to visit several pioneer facilities that are producing printed electronic media; these will begin showing up in our devices before many of us realize how they were manufactured.

D r. R o m a n o a l s o s t r e s s e d t h e understanding of the relationship between NFC technology and Bluetooth.

He stated that both have their advantages and disadvantages and that they should not be seen as competitors but instead as a part

44

Prediciting the Future of Gravure & NFC Technology

of a symbiotic relationship. NFC is very simple to use with devices because it can act passively to run protocols on a device automatically.

It is also more secure and energy-efficient than Bluetooth. Dr. Romano describes NFC technology as the “new business card” as well as the “helper” for Bluetooth. Bluetooth requires pairing with other devices; NFC can be used to automatically pair two devices and enable or disable Bluetooth for enough time to complete the data transfer. Bluetooth’s advantage of much faster data sizes and expanded range come at the cost of higher energy consumption.

Realization of the In-line NFC Printer The direction that NFC will be headed is in-line NFC printing.

Our technology is currently in a stage where the electronics must be printed separately and applied separately from the process-color inks.

Dr. Romano says that “currently I see the point of proliferation o f t h e Ne a r - Fi e l d Communication chip being when packages can be printed in full CMYK with full electronics on the inside as well.” Dr. Romano predicts hybrid presses may become more common as different printing technologies have their advantages and disadvantages -“why suffer using only ON THE RISE NFC technology is currently on the rise. one technology when you Android Beam is a software developed for all post Ice Cream can use the combined Sandwich Android applications that allows for the phone to benefits of two or more interact with NFC tags. technologies at once?”

When packages include printed electronics we will see changes such as the presence of clerks in stores no longer being necessary as we only need to walk into the store or kiosk, find what we want and leave, without ever having to wait in a line again. One misconception that Dr. Romano had also made sure to debunk was the idea that we can “repurpose” older equipment for printed electronics. The necessary mechanical

Sean Garnsey

45

features for a gravure press printing electronics would be different from printing process colors on paper, we would not be able to use an old press for newer products but we could use the basic frames or structures to hybridize this technology, just as some hybrid presses are created these days by placing an inkjet-head array in place of a print unit on offset presses.

Results and Discussion We have not developed the level of sophistication needed to produce complex chips or circuits because ink formulas that work are still undeveloped. Resistance is a major issue in any print technology due to the fact that most print processes do not produce large ink film thicknesses. There are major successes being made in the way of NFC printed electronics, especially in light of the fact that the technology is relatively young. NFC’s major benefit is its ability to be used in conjunction with other useful pieces of the mobile device such as Bluetooth, allowing for the device to quickly switch Bluetooth on and off to make rapid transfers. If printed electronics can be successfully produced, we will see in-line machines that produce NFC integrated into traditional printed products.

Concluding Remarks Gravure technology has all of the appropriate features ideal for use in the printed electronics market. It is true that we have not yet developed highly sophisticated electronics through printed methods.

But it is important to note that with the convergence of technology and research in cell geometries, substrates, inks and other press features, it will be feasible to print not only NFC tags but also a large, dynamic range of other types of products. The economic incentive is present; viable production of printed electronics will be much more efficient than our current manufacturing methods.

The first companies to begin producing products such as NFC chips through gravure will have a major competitive advantage over those that are not. The impact that NFC will have on our current mobile device market will be tremendous. However, the greater implications of this research are that NFC will not be the only technology that evolves and proliferates with printed electronics.

Many unfathomable technologies will be born of and benefit from the fact that we can potentially output complex electronic structures in massive quantities. During my interview, Dr. Frank Romano left me with this final statement: “The possibilities that we can predict in this world are limited only by our imaginations.” If we can think it, it will happen in some way or another.

References Anthony, Sebastien. “Printed Wireless Power Chips Could Be the Kick Start That NFC Needs.” ExtremeTech. ExtremeTech, Oct.-Nov. 2012. Web. 18 Nov. 2012. <http://www.extremetech.com/computing/134288-printed-wireless-power-chipscouldbe-the-kickstart-that-nfc-needs>.

Bhore, Sughosh S. Study of Gravure Printed Nanosilver. Gaa.org. Gravure Association of America, n.d. Web. <http://www.gaa.org/sites/default/files/PDF/ GRAVURESummer2012Lo-res.pdf>.

Bonsor, Kevin, Candace Keener, and Wesley Fenlon. “How RFID Works.”

HowStuffWorks. How Stuff Works, n.d. Web. 18 Nov. 2012. <http://electronics. howstuffworks.com/gadgets/high-tech-gadgets/rfid2.htm>.

Bourdain, Lizzy. “Samsung Slams Apple Commercial - Galaxy S3.” YouTube.YouTube, 19 Sept. 2012. Web. 18 Nov. 2012. <http://www.youtube.com/watch?v=bJafiCKliA8>.

Chandler, Nathan. “What’s the Difference between Mobile Marketing and MobileAdvertising? | Mobile Marketing Watch.” What’s the Difference between Mobile Marketing and Mobile Advertising? | Mobile Marketing Watch. Mobile Marketing Watch, n.d. Web. 19 Nov. 2012. <http://www.mobilemarketingwatch. com/what%E2%80%99s-the-difference-between-mobile-marketing-andmobileadvertising-4570/>.

Clark, Donna A. Major Trends in Gravure Printed Electronics. Digital Commons.

Cal Poly, San Luis Obispo, n.d. Web. <http://digitalcommons.calpoly.edu/cgi/ viewcontent.cgi?article=1026&context=grcsp>.

Gilbert, Jason. “Samsung Mocks IPhone 5, Apple Fanboys Again In New Galaxy S3 Commercial [VIDEO].” The Huffington Post. TheHuffingtonPost.com, 20 Sept.

2012. Web. 18 Nov. 2012. <http://www.huffingtonpost.com/2012/09/20/samsungmocks-iphone-5-commercial_n_1898443.html>.

“How NFC Works.” How Near Field Communication Works. Near Field Communication.org, n.d. Web. 18 Nov. 2012. <http://www.nearfieldcommunication. org/how-it-works.html>.

Park, Hyejin, Hwiwon Kang, Yonggil Lee, Yongsu Park, Jinsoo Noh, and Gyoujin Cho. Fully Roll-to-roll Gravure Printed Rectenna on Plastic Foils for Wireless Power Transmission at 13.56 MHz. Iopscience. IOP Science, n.d. Web. 18 Nov. 2012. <http://iopscience.iop.org/0957-4484/23/34/344006/pdf/09574484_23_34_344006.pdf>.

Romano, Frank. “Future of NFC in Print Technologies.” Telephone interview. 25 Oct. 2012. Romano, Frank. “No Printing Process Dies.” InfoTrends InfoBlog RSS. Infotrends, n.d. Web. 18 Nov. 2012. <http://blog.infotrends.com/?p=8824>.

Sung, Donovan. “Gravure as an Industrially Viable Process for Printed Electronics.”

EECS. UC Berkeley, n.d. Web. <http://www.eecs.berkeley.edu/Pubs/TechRpts/2008/ EECS-2008-70.pdf>.

A

46

Prediciting the Future of Gravure & NFC Technology

Sean Garnsey

47

Authorâ&#x20AC;&#x2122;s Bio Sean Garnsey Sean Garnsey is a fourth year Graphic Communication Management student at Cal Poly. Born in Redwood City, California, Sean grew up around Silicon Valley tech culture and was opened up to the world of Graphic Communication through a family friend who works at Apple, Inc. He has had the opportunity to work with printed electronics in several capacities, from coordinating the production of electrochromic magazine covers during his first year to working in a research clean room at organic electronics group, InnovationLab Gmbh, in Heidelberg, Germany developing demonstrators Lightemmiting Electrochemical Cells (LECs). Sean hopes to one day become a significant figure in the field of printed electronics and functional imaging.

When not involved on campus, he enjoys hiking, music and board games. He loves turtles, does not drink coffee, and will buy anything and everything he needs from Amazon.com.

Watch Seanâ&#x20AC;&#x2122;s exclusive author interview online!

48

54

RESEARCH METHODOLOGY

55

RESULTS AND DISCUSSION

59

CONCLUDING REMARKS

60

REFERENCES

62

Abstract

By Julie Famular March 2012

GR AVURE PRINTING

IN THE FUTURE OF

ELECTRONBEAMCURING

INTRODUCTION

The next development in gravure printing is to incorporate the electron beam curing technology into the gravure print process.

In the past, gravure printing has presented problems such as cost, environmental impacts, and more. If the gravure printing process efficiently incorporates electron beam curing, there will be many benefits. The printing results will have higher quality, use almost no VOCs in the process, and have better properties for food packaging.

Combing EBC with the gravure print process will result in many positive outcomes for all stakeholders associated with gravure printing.

Read Julie Famularâ&#x20AC;&#x2122;s paper online with any tablet or mobile device!

53

Introduction Electron Beam Curing (EBC) is a technology that has been around for many years, but has mainly been used in printing processes besides rotogravure, such as flexography and web offset printing.

EBC has not yet been integrated into the gravure printing process because of certain properties specific to gravure printing, such as ink and drying properties.

There has been research done with EB gravure inks to determine what ink will work for this specific process.

Experiments have also shown that EB gravure inks offer noticeable improvement in product resistance, which is extremely important in food packaging. In the end, to make the EB GRAVURE A general diagram of the gravure printing gravure curing process system. work correctly, drying speed and EB-cure response are critical (Laksin, Evans, Fontaine, Chatterjee, 2011).

There are many stakeholders when it comes to printing because it effects so many people. For example, printing food packaging will affect the environment, effectiveness of marketing the product, have financial implications for both the printing company and client, and effect the customer buying the printed product. With that being said, there is no limit for improving the gravure print process.

According to Helsby, the first experiments with electron beams date from as early as 1920 in the US (Laksin, Evans, Fontaine, Chatterjee, 2011). More recently, this technology is being used in the process of gravure printing. With gravure printing, wet trapping is not an option because each color must be dry before another layer or color is laid down. More recent developments have found that the process can work when using water as a diluent for EB curable gravure inks.

This means that the ink is capable of fast drying and curing after EB

54

Electron Beam Curing in the Future of Gravure Printing

irradiation. The result is enhanced mechanical properties, adhesion and flexibility of the printed image (A Future for EBC, n.d.).

Combining electron beam curing into the gravure print process will yield many benefits: ► ► Higher print quality ► ► Zero VOCs ► ► More consistency in ink and print ► ► Cleaner press room environments EBC also allows for in-line applications which improve aesthetics along with chemical, physical and functional properties of the substrate (Laksin, Evans, Fontaine, Chatterjee, 2011). In particular, this process will be very beneficial for print packaging because it gives special attributes to package barrier properties. Packaging is one of the biggest parts of the printing industry, now estimated to be about $450 million (Uchida, 2008). Packaging also has a huge influence on consumer purchasing decisions, so it is important to focus on ways to improve the quality of print for packaging. EBC should be more widely adopted in rotogravure printing because it will result in many benefits for gravure printing.

Research Methodology EB Ink and Coating Properties One of the reasons EBC is so unique is because cross-linking is induced in a coating that has been applied through a radical polymerization process, giving the substrate special properties (Laksin, Evans, Fontaine, Chatterjee, 2011). Cross linking happens when electrons transfer their energy into the ink layer, exciting ink molecules. Free radicals are formed which initiate a chain reaction. In turn, monomers become cross-linked polymers. This process is better

ELECTROBEAM CURING A diagram of the electrobeam curing process.

Julie Famular

55

for food packaging because photoinitiators are not needed to initiate the process (Schilstra, 2007). High cross-linking density reduces the chances of any undesirable chemical compounds leeching into the food from the packaging. Thus, EB curable inks and coatings are extremely compliant with FDA regulations and guidelines for food packaging (Laksin, n.d.).

Lamination is another important factor in food packaging, as well as packaging in general. It offers more rub resistance, barrier protection, and better mechanical properties and cushioning.

However, lamination can be a hassle. It requires an additional layer of film, doubling the weight of the packaging, adding cost, and making the laminated material packages less recyclable and less environmentally friendly. EBC removes the need for lamination because the cured inks already offer rub resistance. For jobs that don’t require a coating or lamination, this technology sets the finished product apart from others that do not use EBC technology (Savastano, 2009).

Presented at DRUPA 2012, ESI’s newest EB systems are called FlexoBeam and EZCure-CR. FlexoBeam was specifically designed for the Flexo, Offset and Gravure printing presses for flexible packaging converters (Success for ESI, n.d.). Staying consistent with consideration for food and safety regulations, FlexoBeam uses SMARTBEAM Technology. The SMARTBEAM technology has the ability to trace and track operating parameters for food and safety concerns. What is tracked includes curing dose, operating voltage, line speed, and inerting conditions of the print jobs. If customers request this data at some point in the future, the technology has the ability to trace back as far as a year and see what the operating parameters were. The EZCure EB systems have the capability to cure over SMARTBEAM Flexobeam uses SMARTBEAM print varnishes put in technolog y, which has the ability to trace and track place to replace film operating parameters for food and safety concerns. laminations. Replacing

56

Electron Beam Curing in the Future of Gravure Printing

laminations with special EB coatings allow for amazing graphics, reduced costs, and product protection.

The lamination or combination of several polymers and their properties create barriers which also extend a product’s shelf life.

New technology for improving flexible package barrier properties is important so people don’t end up with a comprised package resulting from water vapor, gas, and aromas (Uchida, 2008). Again, having these properties is great for food packaging. The barrier is helpful in preventing factors such as moisture, light, aroma, and water from affecting the food product inside the packaging, or the shelf life of the packaging (Uchida, 2008). The cross linkage properties of EBC provides an oxygen barrier so that in humid conditions the adhesion of the package will not be affected.

Environmental Implications In the past, the print industry has received a fairly poor reputation when it comes to being sustainable. Within the more recent years, however, the print industry has been developing new technologies to improve sustainability. EBC is an environmentally intelligent process because there are no VOC emissions. VOCs are very harmful to air quality, and have a negative effect on human health (An Intro to Indoor Air Quality, 2012). The EPA has been increasing VOC limitations, making it critical to find alternative materials that are not harmful and do not emit VOCs. In traditional printing, The top layer of film is solvent-based which allows for VOCs to escape into the air. EBC does not have this problem because reactive diluents are the components of the top layer, and it does not emit VOCs (Uchida, 2008).

The process of gravure printing has one of the highest implications of VOC emissions out of all of the printing processes because it is mostly dominated by solvent based systems that require fast drying times (Laksin, Evans, Fontaine, Chatterjee, 2011). This makes gravure printing one of the least attractive to those who are hoping to be sustainable. Water based inks are used in gravure as well, but if the printers need fast drying, there is usually some kind of volatile compound used to control viscosity. Publication printers usually use solvent-based inks because they are very concerned with speed. This is where EBC steps into the gravure process to offer a more sustainable way to print. Combing EBC with air and heat drying for water based inks will allow for high speed printing and desired physical properties for the finished product. (Laksin, Evans,

Julie Famular

57

Fontaine, Chatterjee, 2011). To make this process work, each layer must be completely dried before applying the next layer of ink.

Speed and quality will not be compromised when using EBC in the gravure process.

Print Quality If EBC is integrated into the gravure print process, the finished products will be even higher quality. Michael Fontaine, senior product and process engineer for AMGRAPH says, â&#x20AC;&#x153;EB gravure is a game-changing technology, as it is completely VOC free. Cured inks offer rub resistance without adding coating for jobs that donâ&#x20AC;&#x2122;t require a coatingâ&#x20AC;? (Savastano, 2009). Increased rub resistance means packages will not lose their image or quality as fast. Gravure is known as one of the highest quality print technologies available to packaging converters (Laksin, Evans, Fontaine, Chatterjee, 2011) so combining it with EBC technology would really set gravure apart from other print technologies. Gravure is able to produce such great quality because of the engraved cells. While in lithography, dot sizes can be changed, gravure can change the size, shape, and depth of the cylinder cells, so ink being transferred onto the paper provides better detail and accuracy.

Deeper gravure cells even HIGHER QUALITY EB curing enhances print quality allow for special-effect by increasing the color and image accuracy. colors such as metallics, resulting in visual effects that no other printing method can offer (Laksin, Evans, Fontaine, Chatterjee, 2011).

Other quality improvements resulting from EBC are improved ink consistency and amazing visual appearance.

EBC enhances print quality mainly by increasing the color and image accuracy (Uchida, 2008). This is vital because images and text on a package are key when attracting customers. The fact that EBC tends to be more effective with thinner inks and coatings

58

Electron Beam Curing in the Future of Gravure Printing

contributes to the higher quality it reproduces (Clark, 2009). EB curable inks generally use 100% solid pigment and resin blends.

This contributes to the high quality of EB gravure printing because the ink transfers easily and instantly converts from liquid to solid state. The high pigment to binder ratio gives the resulting product high color strength (Laksin, 2010).

Results and Discussion When considering all of the benefits of using EBC with gravure printing, one of the only feasible reasons why it has not penetrated the market more in the past is its cost. Previously, EBC methods were associated with excessively high initial costs for plant and equipment capital investment (Uchida, 2008). In the most recent years, however, the cost of EBC has decreased enough that companies are willing to consider implementing the technology. One of the ways to help make EBC cheaper is to simplify the processing line.

If EBC can be used in gravure with just one curing station, there will be less machinery, less space required, and higher efficiency.

All of these will help lower the cost of EBC and make it more popular and realistic to use for gravure printing (Uchida, 2008).

As EBC technology advances, the cost will continue to drop and the technology will become increasingly popular because of its many benefits.

The future of gravure printing, EBC, and all print processes is increased sustainability. Ideally, the goal is to have a VOC free press room. I predict that for gravure to have a stronger presence and popularity in the print industry, it must find a way to become more sustainable. EBC is a great transition for gravure on the path to sustainability. EB curable gravure inks have no VOCs while still drying fast enough for publication runs and compatibility with dry trapping (Laksin, Evans, Fontaine, Chatterjee, 2011).

The beauty of EB curable inks is that they can be easily run on existing gravure presses (Laksin, Fontaine, Evans, Grossman, 2010).

In the article EB Gravure: Novel Printing Concept for Sustainable Packaging, different ink resins and properties are explored to find an EB curable ink compatible with gravure printing. EB curing of inks requires a specific dose because cross linking density happens depending on resin chemistry, pigment-to-binder ratio; and target print density (Laksin, Evans, Fontaine, Chatterjee, 2011). Inks used in this experiment used polyurethane-based dispersions and one based on acrylic backbone polymer. This research offers many opportunities for developing EB gravure inks that will work well

Julie Famular

59

Rotogravure will continue to have an important presence in packaging print. Although this has been questioned in recent years, there are many changing factors to improve the process and ensure gravure printing will still have a place in the industry. New technologies have allowed for even faster cylinder engraving so they can be engraved in minutes instead of hours. This will lower costs and improve pressroom efficiency. Time can also be saved by testing everything (harness, size, roughness, weight) of the cylinder before shipping the cylinder to the customer. Several problems with gravure include the need for gravure to become more green, include cleaner presses and press rooms, and change from solvent-based inks (where EBC and inks will play a hand in gravureâ&#x20AC;&#x2122;s future).

Laser engraving will also most likely play a huge role in gravureâ&#x20AC;&#x2122;s future. Laser engraving produces cleaner cells and is much faster than the traditional engraving process. Laser engraving also allows for in-house engraving without using any regulated chemicals (Spaulding, 2012). With all these improvements, gravure is very attractive because it can run at very high speeds, produces high quality printed products, and is one of the simplest printing process despite the time of cylinder engraving. If EBC and inks play into this equation, the process will be more green and produce even higher quality.

Concluding Remarks Gravure printing is one of the best printing processes bescause it is simple and efficient. Newer technology has helped the process improve even more by reducing cylinder engraving time, reduced costs in shipping, materials, and initial setup, cleaner pressrooms, and technology to reproduce products with higher quality. Although

60

Electron Beam Curing in the Future of Gravure Printing

the gravure printing process is easy and effective, there are still many ways that it can be improved to provide more for its stakeholders.

EBC is a technology that will benefit the gravure print process. One of the main problems with gravure is that it is not very sustainable.

Using EB curable inks in the process will help the process be more sustainable to the point where no VOCs are emitted. This will result in improved air quality. Quality of gravure printed products will improve as well if EBC is used in the process. This technology allows for amazing color reproduction. EBC also allows for barrier properties that can be very beneficial to food packaging. The process gives the product certain barrier properties to keep the packaging as new as possible and keep food fresh and protected from outside variables.

The idea of EB gravure printing has mostly positive connotations, but I predict that it will take a while to be adopted by gravure printers. Gravure printers do not have much competition, and there is not necessarily a need for better technology because gravure already prints high quality, fast, and effectively. Many printers become set in their ways as well because they feel if something is not broken, why fix it. Trying something new can sometimes cause problems and reduce efficiency for a period of time. Gravure printers would need to invest in the technology as well, which is why it is so important to find ways to reduce the initial cost of EBC. The future for EB gravure printing is bright, and this technology needs to be more widely adopted. New developments are allowing for lower initial costs of EB gravure printing so that it can be more widely adopted. If costs continue to drop, I predict that many gravure printers will adopt this technology. With safety regulations for the environment and food packaging becoming tighter, there may be no choice but to begin using EB curable inks because they present a zero VOC option. New technologies will continue to help printers stay competitive. EBC technology could have a very important place in the print for packaging industry. As the costs of this technology decrease and it becomes easier to adopt in the gravure printing process, all stakeholders related to gravure packaging print will benefit.

A

in the gravure print process (Laksin, Evans, Fontaine, Chatterjee, 2011). IdeOn and Amgraph Packaging are two other companies that have explored EB curable inks. These companies began to explore EB curable inks around 2010. IdeOn and Amgraph also found that the best resins were polyurethanes. After testing different ink combinations on press, they found that the inks they created had desirable and consistent print densities and solvent resistance.

They ran the inks at different press speeds: 500, 750, and 800+ feet per minute. About 60 solvents were used for the four-color trap. Although solvents were still used, it was a great improvement from the normal amount used (Laksin, Fontaine, Evans, Grossman, 2010). The development of viable EB curable inks is critical for the future of integrating EBC with the gravure process.

Julie Famular

61

References Laksin, Mikhail, Sean Evans, Ken Fontaine, and Subh Chatterjee. “EB Gravure: Novel Printing Concept for Sustainable Printing.” Radtech.org. N.p., 2011. Web. 5 Mar. 2013. <http://radtech.org/RTReport_pdfs/ebgravure_Summer_2011.pdf> Laksin, Mikhail, Ken Fontaine, Sean Evans, and Jo Grosman. “Novel Printing Concept for Sustainable Packaging.” Package Printing, Aug. 2010. Web. 05 Mar. 2013. <http://www.packageprinting.com/article/eb-curing-provides-meansaddressing-shortcomings-aqueous-gravure-inks/1>.

Uchida, Sayaka. Utility & Advantages of Electron Beam Curing in Flexible Packaging.

Iopp.org. N.p., 8 Mar. 2008. Web. 5 Mar. 2013. <http://www.iopp.org/files/public/ UchidaSJSUEBCuring.pdf>.

Schilstra, Durk. “EB Curing- a Promising Radiation Technology.” Ebeam.com.

N.p., 2007. Web. 5 Mar. 2013. <http://www.ebeam.com/pdfs/FGI_2_2007_EB%20 Curing%20Article.pdf>.

Laksin, Mikhail. Electron Beam Curing in Packaging- Challenges and Trends. Rep. Radtecho, n.d. Web. 5 Mar. 2013.<http://72.52.184.8/~radtecho/RTReport_pdfs/ ElectronBeamCuringinPackaging-ChallengesandTrends.pdf>.

“Success for ESI.” Energy Sciences, Inc. ESI, n.d. Web. 05 Mar. 2013. <http:// www.ebeam.com/>.

Savastano, David. “Emphasis on Environment Leads AMGRAPH, IdeOn to Develop EB Curable Gravure Inks.” Ink World Magazine. Ink World, 2009. Web. 05 Mar. 2013. <http://www.inkworldmagazine.com/articles/2009/12/emphasis-onenvironment-leads-amgraph-ideon-to-dev>.

Laksin, Mikhail. “Printing Today, EB Curing Tomorrow...” Ink World Magazine.

N.p., n.d. Web. 05 Mar. 2013. <http://www.inkworldmagazine.com/articles/2010/05/ experts-opinion-printing-today-eb-curing-tomorrow>.

“Electron Beam Curing Ink.” Recent Changes RSS. N.p., n.d. Web. 06 Feb. 2013. <http://printwiki.org/Electron_Beam_Curing_Ink> “A Future for Electron Beam Curing.” Radtech Europe: The European Association for the Promotion of UV and EB Curing Technology. N.p., n.d. Web. 06 Feb. 2013.<http://www.radtech-europe.com/news/radtech-europe/2012/future-electronbeam-curing> “An Introduction to Indoor Air Quality: Volatile Organic Compounds (VOCs).”

EPA. Environmental Protection Agency, 09 July 2012. Web. 05 Mar. 2013. <http:// www.epa.gov/iaq/voc.html> Spaulding, Mark A. “The Future of Gravure Packaging Printing Is NOT an Oxymoron.” The Converting Curmudgeon. Wordpess, 4 Mar. 2012. Web. 05 Mar. 2013. <http://convertingcurmudgeon.com/2012/03/04/the-future-of-gravurepackaging-printing-is-not-an-oxymoron/> Clark, Emily. “An Innovative Way to Print: Ultra Violet and Electron Beam Curing.”

Iopp.org/files/public/RochesterInstituteEmilyClark. N.p., Jan. 2009. Web. 05 Mar. 2013. <http://www.iopp.org/files/public/RochesterInstituteEmilyClark.pdf>.

Laksin, Mikhail, Ken Fontaine, Sean Evans, and Jo Grosman. “Novel Printing Concept for Sustainable Packaging.” Package Printing August 2010. MarkAndy, Aug. 2010.

Web. 05 Mar. 2013. <http://www.mydigitalpublication.com/publication/?i=44550>.

62

Electron Beam Curing in the Future of Gravure Printing

Julie Famular

63

Author’s Bio Julie Famular Julie is currently a senior at California Polytechnic State University, San Luis Obispo. She is a Graphic Communication major with a concentration in management. Being a student in the Graphic Communication Department at Cal Poly has allowed Julie to learn about her combined interests in creativity, science, technology and business management. Julie has loved her time at Cal Poly and enjoys weekends filled with hiking and going to the beach. Julie’s professional interests combine social media, marketing, design, management and PR. After graduation, Julie hopes to find a full time job in the Bay Area.

Watch Julie’s exclusive author interview online! Find out more about what she enjoys about GrC!

64

70

METHODOLOGY

70

RESULTS

72

CONCLUDING REMARKS

77

REFERENCES

78

Abstract

By Catherine Wang June 2012

AS A STRONG CONTRIBUTOR TO GR AVURE PRINTING

IMPRESSION ROLLER

EVALUATINGTHE

INTRODUCTION

Rotogravure printing is a simple printing process that ensures consistency and high quality reproduction. With only four basic parts (doctor blade, engraved cylinder, ink fountain, and impression roller), it is easy to surmise that quality simple to attain. By specifically evaluating the impression cylinder, it was discovered that although it may be simple in concept, there were varying factors that contribute to its function on the press. The roller covering, bearers, and size are factors contributing to the varying types of impression rollers used. Factors affecting its role include storage, applying electrostatic assist, and Shore A rubber hardness.

Read Catherine Wangâ&#x20AC;&#x2122;s paper online with any tablet or mobile device!

69

Introduction Rotogravure printing has been characterized by the reproduction of high quality and consistent images and graphics. Looking at the product under a loupe will show serrated edges, a sure way to confirm that it is a gravure printed product. Look even closer and one would find the diamond-shaped cells that mark gravure as a unique process. But how is it that ink was transferred onto the substrate from cells only microns wide and deep to the substrate that glides on? Much research has been done to explain the quality of gravure GRAVURE PRESS Each unit of a gravure press consists tones and how to obtain of four basic parts. The impression roller’s main purpose is even better ink quality, yet to help the engraved cylinder transfer ink from the cell to the rubber covered, the substrate. friction-driven impression roller, often briefly mentioned, is forgotten amidst the central engraved cylinder. As a part of the printing unit, the impression roller, although basic in design, has complex characteristics that warrant further explanation.

Conceptually, rotogravure is a very simple printing process that has few components to ensure high printing efficacy. Having few variables to control in production guarantees a higher print consistency and quality. The gravure press has multiple units and each unit consists of four basic parts: the engraved cylinder, the ink fountain, the doctor blade, and the impression roller. Given the simplistic structure of the printing press, each part is a vital asset in contributing to the output, especialy the impression roller.

Methodology To better grasp the function of how an impression roller works and its effects on print quality, the main parts of the roller were inspected. Information regarding impression roller structure and layout were achieved through secondary research.

The roller’s main purpose is to help the engraved cylinder transfer ink from the cell to the substrate. Its structure consists of several

70

Evaluating the Gravure Roller as a Strong Contributor to Gravure Printing

core parts that impact the substrate. Beginning from the outside, the cylinder is made up of a tubular sleeve or roll covering. The sleeve assists by applying stability and strength during printing. At the core is steel, which provides stability while maintaining strong pressure against the cylinder and the substrate. However, other materials have been used to accommodate for “special handling problems” presented from the heavy impact of steel. Lighter materials include aluminum and magnesium (GEF and GAA, 2003).

To apply even but strong pressure, the rubber roller must meet several specifications. Selecting the materials for a roller covering must take strength into account as it wears down against the cylinder after many impressions. Some questions to ask are: ► ► Will the press be running at high speed? ► ► What are the chances that friction will reduce printing efficacy?

Roller coverings need to have an elastomer polymer (such as rubber or polyurethane) to help increase the rate that the roller will bounce back to its original shape upon impact. Since the roller must return to its original form quickly, the elastomer occupies 30-40% of the roller (GEF and GAA, 2003). Factors to include are: hardness (measured in Shore A scale), tensile strength, elongation, tear strength, resistance to chemicals and oil, resistance to heat, abrasion resistance, electrical acceptance, adhesion, and hysteresis (affected by cause). Hardness is the driving factor in impression rollers. It varies from 60 to 100, depending on the substrate. The best is 60-80 for film and laminates and 80-90 for paper and paperboard (Cooper, n.d.). The hardness of the roller affects how the impression roll will function based on its resiliency, heat buildup properties, and compression rate.

The impression roller may be overlooked because of its size. Although it is smaller than an engraved cylinder, its dimensions are better fitted to create a narrow nip point for better and sharper printing (Kipphan, 2001). Its optimal size is inversely proportionate to the engraved cylinder. Originally, there was a three-cylinder system where a larger cylinder was situated above the impression roller. This extra weight on the roller increased the pressure surmounted and was thus effectual in creating a stronger nip point, without it there would be deflection problems. A two-roller system was introduced to create a higher speed printing press. The high speed induces a

Catherine Wang

71

higher friction rate generating more heat; this is currently used today. This setup is known as the deflection-compensated impression roller. The cylinders are situated above hydraulic supports (saddles).

These saddles serve as an option to cool the heated cylinder through the hydraulic fluid as it lubricates and cooles down the cylinder.

Before, impression rollers were significantly smaller than the engraved cylinder. With the double cylinder, faster press speeds allow the larger diameter roller to spread the amount of work done over a longer period. Some of the older cylinders used six to seven inch diameter cylinders, but with larger production sizes impression rollers were maxing out their speed. As a result, excessive heat from friction quickly shortened the lifespan of a roller covering and caused many problems (GEF and GAA, 2003). To fix this, printers and manufacturers found that using a cylinder with a larger diameter resulted in a greater surface area to cover the total amount of work done in the impression nip. All else being equal, the larger the diameter of the impression roller, the smaller the stresses on the web. If an impression roller is too large, however, it would cause print distortions because of extended in the nip area.

Results Impression rollers have storage requirements to prevent premature wear and tear. Environmental hazards, such as exposure to light, oxygen presence, the humidity of the pressroom, and flyaway solvents may decrease the lifespan of a roller. Light exposure from wall windows and ceiling windows allow ultraviolet (UV) light to interact with the polymers on the roller. The harmful UV rays may degrade the polymers on the roller or react with the polymers that degrade the polymer, affecting the impression roller quality.

Rather than removing windows or covering them, cover the roller with opaque paper to diffuse the light’s rays, preventing it from directly affecting the polymers (GEF and GAA, 2003). Rubber is best stored at cold temperatures, but needs to be warmed up to pressroom temperature. A cold roller may crack or change physical properties before it is started up on the press; a warm roller prevents this unnecessary stress and heat. The surface of the roller may also crack from the presence of ozone (a compound formed from the interaction in an oxygenated environment and electric charges or UV light). Ozone interacts with polymers, reducing their ability to maintain resilience and strength.

The rubber roller shouldn’t be stored flat. Just as webs of paper and

72

Evaluating the Gravure Roller as a Strong Contributor to Gravure Printing

substrate are stored vertically to prevent flattened parts of the roll, the impression roller follows the same principle. If the roller was stored flat on the ground, gravity would exert force and pressure onto the rubber-ground surface area. The extra pressure would flatten the ground-facing side, leaving an undesirable flat surface on an otherwise round cylinder. Most rollers are kept in the original box that they were shipped in or on special roller-designated racks near the press.

Lastly, rollers don’t have an engraved image and need to be washed of ink and dried to keep future press runs clean and consistent. Storing it under a sheet will protect it from flying dust from the substrate.

Ink, as a fluid, has a meniscus, where there is a slight pull toward the center of a liquid, meaning that the ink in a cell is never really full. The meniscus is concave, and while printing high speeds, ink needs to be pushed (or pulled) from the cell onto the substrate. The ink adheres to the walls of the engraved cell and is held it its cell by centripetal force. Imagine filling a bucket of water and fling it in a circular arc The fluid doesn’t spill or slosh out (unless the bucket is stopped immediately). Why? The ink is held in by the centripetal force that is applied as the bucket changes directions. Identifying the problem that ink would be hard to pull from an even faster moving engraved cylinder running at a high speed, printers developed electrostatic assist (also known as ESA). As its name implies, electricity, which carries an opposing charge to the ink, assists the transfer of ink to the substrate. Ink has a slight polarity that oppositely attracts the static from the ESA on the impression roller. To transfer ink from cells to a substrate, the ESA attracts the ink to flow above the cell, improving contact with the web to transfer via capillary action. This is especially vital for the smaller ink cells, such as the midtones and highlights.

The electricity applied to the impression cylinder must be in a certain range to ensure equal transfer. Foremost, the roller must be able to handle the resistance applied.

NATIONAL GEOGRAPHIC The National Geographic cover is printed by using the gravure printing process.

Catherine Wang

73

Not all impression rollers are built to handle the electric current.

The electric resistance must be low enough to maintain an electric field in the nip area, but not too high to prevent sparking. Paul Fleming, an engineering professor at Western Michigan University suggests that on average, approximately 500-1000 volts are applied per millimeter (0.001”) of web thickness. Conversely, the rubber on the roller must have a high enough resistance to maintain the charge as its is transferred to the web.

Some products that are printed with ESA have direct evidence that it is printed by rotogravure. Ink attraction results when an electrically charged roller touches the substrate, causing static electricity.

T h i s i s w h y g r a v u re printed products such as National Geographic will crackle and stick together when first opening its pages. This indicates that the substrate was subjected to ESA. The static is dispelled by cutting the polar attraction or by sending the electricity to a grounded object, such as a human hand.

Without an electrostatic application, problems that WITH ESA (TOP), WITHOUT ESA (BOTTOM) Test products to show the advantages of printing with arise from ink transfer electrostatic assist. from cells, especially smaller ones become more apparent and challenging. Many smaller cells have a harder transfer rate between to substrate. Thus, in some printed products, there are some noticeable white spot flecks, which is more evident in solid colored images. The white specks are known as “snowflaking.”

Without the ESA, problems of transferring ink from cells, especially the smaller ones, becomes more challenging. If many cells’ inks are

74

Evaluating the Gravure Roller as a Strong Contributor to Gravure Printing

not coming out, there are noticeable white spots on some printed products, most noticeable in images. The white splotches are an effect known as “snowflaking,” which is also determined by blank dots in images or some pixilated graininess. Before the idea of electrostatic assist, numerous attempts to increase the probability of ink transfer, varied from increased “printing pressures, harder rubber impression rollers, unique etching techniques, and ink manipulation” (GEF and GAA, 2003). None of these worked as effectively to transfer ink to the substrate as much as the substrate to the ink. The polarity of the ink helps to transfer the ink the best, although other alternatives for non-polar inks and water-based inks have been tested true as well.

Printing with ESA has greatly reduced the snowflaking problem.

Improvements to the press include better print quality, less production waste, the use of a lowerbasis substrate while also printing at faster speeds.

This also reduced heat buildup of the impression roller (reduced to lower speeds), resulting in a longer lasting roller.

ELECTROSTATIC ASSIST Finished printing products comparing the differences between printing with and without Electrostatic Assist.

Print quality also depends on the rubber hardness component, which are measured in Shore A values. Professor Akshay Joshi from Pune Vidhyarthi Griha’s College of Engineering and Technology discovered that precise ink transfer and pickup from cell to substrate depends heavily on the impression roller hardness. He found that there are strong correlations between hardness, nip width, and net pressure acting at the nip. All three variables are hard to control for each press run to meet customer specifications, but Professor Joshi recommends standardizing the selection process. He also found that determining the correct Shore value for a roller is essential in achieving and meeting high print quality standards.

Several problems exist with impression rollers. The first is static generation. At the nip, where the impression roller meets up with the substrate and engraved cylinder, there is a lot of friction. This

Catherine Wang

75

Another problem is whiskering, or when ink is drawn from the printed image, out of its â&#x20AC;&#x2DC;boundaries.â&#x20AC;&#x2122; It is usually found when a solid area is printed near a non-image area. This problem is created from ink separation from the cylinder and the paper at the nip. Press and pressroom conditions create whiskering because of the presence of electricity. As the cylinder and paper rotate away from each other, the ink begins to travel in extended directions because of the polarity.

Low humidity, high press speed and wet solvent charges the ink, subjecting it to electric charges that let the ink spread. To eliminate the whiskers, a solution is to add moisture in the pressroom or on the web. The extra water helps discharge electricity, completing the arc. The presence of static brushes or tinsel can reduce the presence of electricity, but it doesnâ&#x20AC;&#x2122;t eliminate it. Keep the press grounded so that the electricity can complete its circuit. Some have found that wiping talcum powder on the roller can reduce static buildup from rubber-induced friction. This affects the triboelectric properties that in effect will reduce the presence of static.

Friction and rubber contact also causes heat buildup within the roller, paper and press. Each roller has a different reaction to heat with varying rubber composition properties. Thick rollers tend to flex more. Thin coverings are generally cooler because of less material present to act as a heat sink. Thus, the impression roller diameter varies less under thermal contact.

There is a direct relationship between nip width and rubber flexing.

Having a narrow nip reduces flexing of the covering and heat buildup. Limiting the amount of pressure used also reduces heat build-up, but there is a minimum tolerance to maintain impression quality. The main culprit may stem from the rubber itself. Rubber has great resiliency but is a poor conductor of heat. The heat may be on one side of the roller, but is not distributed evenly throughout the roller. Heat at the ends is usually caused by deflection. To best prevent impression roller heat build-up, run the press at low speeds to warm up the roller. Newer press designs have one impression roller nip and use larger diameter rollers. This helps to control covering

76

Evaluating the Gravure Roller as a Strong Contributor to Gravure Printing

temperature by spreading the work over a larger surface area.

Tension is absolutely essential in gravure. The impression roller helps set and maintain tension as the web travels through the press while ink layers are applied. Tension is important to reduce paper bounce, wrinkles, and lateral movement. The impression roller helps pull the paper through the printing unit. If there is a tapered impression roller, the web may move sideways due to the unevenness of the roller. A worn impression roller can have ring-like grooves on its surface or an uneven diameter from end to end. Having grooves may cause wrinkles in the web, which could lead to a web break. Likewise, an out-of-round cylinder applies uneven loading on the web. By applying varying pressures on the substrate, the web may pull from the roller faster or slower, which is a negative effect contributing to high-frequency oscillation of the substrate.

Another contributor is the attraction of paper dust and flakes; ink spots affect the roller, reducing its coefficient of friction. A smoother surface reduces tension because of the less firm grip on the web.

Covering hardness, thickness, and diameter affect nip width and impression pressure.

Print quality most certainly depends on impression roller function.

When the substrate to be determined has been printed, which then dictates what type of impression roller will be used. Factors such as caliper, compressibility, smoothness, porosity, and absorption of impression rollers entirely affect print quality. Substrate properties dictate what kind of impression roller needs to be used. The impression roller creates pressure and nip size to best capture the ink from the wells.

Concluding Remarks Despite the notion that gravure printing relies completely on the engraved cylinder, doctor blade, and ink, it has been proven that the impression roller affects gravure printing quality, both with advantages and disadvantages. A scientific approach to an inspection of the impression roller explains that although the functionality is simple, the process requires a multitude of factors to guarantee the proper role of transferring ink to substrate.

A

friction can lead to static generation, which can build to very high voltages on insulating surfaces such as the web, especially if the moisture content is low, and on non-ESA impression rollers.

Electricity continues its circuit until its grounded. When the energy is grounded in the pressroom, it may land on cylinders or a press frame. The spark from these may cause a fire.

Catherine Wang

77

References Cooper, Kevin. “Rotogravure Printing.” California Polytechnic State University. n.d. Presentation. 2013.

Fleming III, Paul D. “Gravure Impression Roller.” Gravure Printing. Western Michigan University. n.d. Web. 22 January 2013.

Gravure Education Foundation and Gravure Association of America. “Gravure: Process and Technology”. 1 November 2003. Print. 22 January 2013 Kipphan, Helmut. “Handbook of Print Media: Technologies and Production Methods.” 31 July 2001. Print. 22 January 2013.

Joshi, Akshay. “The Impact of Shore Hardness on Gravure Print Fidelity.” 2009.

GravurExchange. Web. 22 January 2013.

78

79

Authorâ&#x20AC;&#x2122;s Bio Catherine Wang Catherine is a senior at Cal Poly, graduating with a B.S. in Graphic Communication. Interestingly, her change in major from nutrition has given her the chance to apply a scientific approach on discovering her creative side. Her artistic talents and eye for design have led to accolades from the New Student Programs on-campus and local businesses in San Luis Obispo. When not dreaming up of new concepts and designs, Catherine spends her time volunteering at hospitals and venturing into the wild.

Watch Catherineâ&#x20AC;&#x2122;s exclusive author interview online! Hear more about her passion for volunteerism!

80

TAGA 2014

Student Chapter California Polytechnic State University, San Luis Obispo

TAGA Student Chapter in the Bindery & Finishing Lab

TAGA Chapter at Graphic Communication Fall Picnic

View our chapter promotional video: “This is TAGA”.

84

Chapter officers goofing off in the California sun!

Check out some of our chapter’s side-projects

85

TAGA 2014

Chapter Advisor

Xiaoying Rong Associate Professor, Graphic Communication Department TAGA Advisor California Polytechnic State University Dr. Xiaoying Rong is an Associate Professor in the Graphic Communication Department at Cal Poly State University, San Luis Obispo. Dr. Rong joined Cal Poly in 2005. Her expertise areas are screen printing, commercial offset printing, digital printing, inks and substrates, printability, wide and grand format printing, industrilal printing, consumer packaging, and printed electronics. Dr. Rongâ&#x20AC;&#x2122;s most recent research includes screen printing characterization for low viscosity and thin ink film, screen printing for electroluminescent display, integration of functional printing to commercial printing products, active and intelligent packaging solutions. Dr. Xiaoying Rong received her Ph.D. degree from Western Michigan University in Paper Engineering, Chemical Engineering, and Imaging.

86

Chapter Members California Polytechnic State University, San Luis Obispo

Not Pictured India Tatro Anna Williams Ellie Trebino Kristina Sanders Connor Foltyn-Smith Kayla Lake Julia Pini Allison Premzic Corrina Powell Janine Sato Isabella Baldwin Taya Arnone Kelly Learn Kristina Sanderson Alexa Wong Kristen Kumagai

87

colophon.

This journal was produced entirely by students of the TAGA chapter in the Graphic Communication department of California Polytechnic State University, San Luis Obispo. All design, printing, and overall production work was completed in on-campus facilities.

Adobe Illustrator, InDesign, and Photoshop were used in the design of this journal.

The fonts used in the text of this journal include Adobe Garamond Pro, Avenir Next LT Pro, Trade Gothic Next LT Pro, and Klint Std. The journal was printed on a Konika Minolta C8000 Digital Press.

The inside pages of this journal were printed on Futura 100 pound dull text paper and the cover of the journal is printed on Futura 100 pound dull cover paper.

Substrates were cut to the proper size using a Polar cutter and the journal was perfect bound using a Duplo DB-280 Perfect Binder.

The Cal Poly TAGA website (calpolytaga.com) was created using wordpress (wordpress.com).

To link to the TAGA website, Ricohâ&#x20AC;&#x2122;s Clickable Paper technology was incorporated into the printed journal.

89

thank you!

We would like to thank our sponsors and supporters: NewPage Ricoh Konica Minolta Duplo Printing Industries of America: Southern California University Graphic Systems Cal Poly Graphic Communication program

We would also like to give a special thanks to Dr. Frank Romano & Jim Kersten for their generous donations.

Thank you Brian Lawler, Ken Macro, Korla McFall & Michelle Godfrey for your assistance with chapter functions.

Finally, thank you to Dr. Xiaoying Rong for overseeing Cal Polyâ&#x20AC;&#x2122;s TAGA chapter and helping complete our vision.

91