INTERNATIONAL SYMPOSIUM Sheraton Malpensa Hotel, 24th and 25th October 2012
Multilayered film for flexible packaging, manufactured with blown film technology. Speakers: Diego Castiglioni, Technical Director, Bandera Paolo Ceol, Product Manager, Bandera
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Film for flexible packaging Number of layers
Main applications for blown film
MONO-LAYER
FILM FOR BAGS AND SACKS, GENERIC PACKAGING, SHRINK FILM, LAMINATION.
3 LAYERS
SHRINK FILM, LAMINATING FILM, STRETCH HOOD FILM, PROTECTIVE FILM, FILM FOR TECHNICAL APPLICATIONS, INDUSTRIAL FILM.
5 LAYERS
LAMINATING FILM, BARRIER FILM, FILM FOR TECHNICAL APPLICATIONS, PROTECTIVE FILM, AUTOCLAVE FILM, INDUSTRIAL FILM.
7 LAYERS, 9 LAYERS, ...
HIGH AND VERY HIGH STRENGTH BARRIER FILM, FILM FOR TECHNICAL APPLICATIONS, AUTOCLAVE FILM, THERMOFORMING FILM, LAMINATING FILM.
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Mono-layer blown film Resins: LDPE, LLDPE, MDPE, HDPE, EVA (in blend). Advantages: Low cost investment system. Disadvantages: Low flexibility, inferior quality, high thickness, impossible to differentiate between the layers.
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Advantages of multi-layered coextrusion
Greater flexibility Reduces the production cost Optimizes the use of resin and additives Reduces the thickness of the film Increases the mechanical properties Increases the quality Improves the barrier effect Commercial incentive (marketing: competitive advantage and commercial lever).
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3-layer blown film Resins: LDPE, LLDPE, mLLDPE, MDPE, HDPE, EVA, coPP. Advantages: greater flexibility, reduces production costs, reduces thickness, better mechanical properties. mLLDPE: increase in mechanical and optical properties (transparency, shininess, glossiness). LDPE + MDPE / HDPE: greater rigidity in packaging. LLDPE / EVA: welded/peelable layer. coPP: heat-resistant, effective non-collant.
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Examples of triple-layered film for flexibile packaging
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5-layer blown film Resins: LDPE, LLDPE, mLLDPE, MDPE, HDPE, EVA, coPP, coPA, PA6, EVOH, adhesive, ionomer. PE: confers a barrier against water vapour; weldability. PA (Nylon), EVOH (Etilene-Vinil-Alcol): confer the barrier effect. PA: gives good protection against gas (O2, CO2, N2) EVOH: gives better protection against oxygen and water vapour. Adesivo / Tie: copolymer acid maleic anhydride, for adhesion between PA and EVOH and PE. Ionomero (Surlyn™): forms mechanical and chemical resistance, weldability, suitable for direct contact with food.
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Adhesive or the Tie (Bonding) Layer
PA (polar resin) is not compatible with either PE (apolar resin) or PP. A layer of adhesive material is needed to ensure the adhesion between the layers of PE or PP and PA. The adhesive resins are polymers which adhere by means of a chemical reaction with PA and mix with PE and PP. Examples of adhesive resins for barrier layers: Bynel (DuPont), Plexxar (LyondellBasell), Orevac (Arkema), Admer (Mitsui). An adhesive layer is not necessary for PA/EVA (with a high percentage of VA) and PA/EVOH. A new generation of adhesives which mix directly with PE.
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5-layer blown film Examples of applications for 5-layer film: Symmetrical formulation with a central layer of PA – Asymmetrical formulation with two layers of PA – Symmetrical formulation with a central layer of EVOH – Laminating film in calender Advantages and disadvantages of the asymmetrical structure: – The Curling phenomenon – General specifications of 5-layer blown film –
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Symmetrical structure of 5-layer film with PA The structure of 5-layer film, symmetrical type (central layer of PA). Total thickness of the film: 50 µ ÷ 250 µ; laminating film. The thickness of the layer of PA relative to the total thickness depends on the application of the material (approximately 5÷30%). The minimum thickness of the layer of PA ultimately depends on the client’s personal specifications (minimum thickness in μ which guarantees the properties of the packaging barrier requested by the end user.)
Types of structure: PE/Tie/PA/Tie/PE; PP/Tie/PA/Tie/PE; PE/Tie/PA/Tie/PP PP/Tie/PA/Tie/PP 10
Asymmetric structure of 5-layer film with PA. Asymmetric structure of 5-layer film (central layer and external layer of PA).
Total thicknesses: 65 µ÷150 µ, for the film pouch, for the film top tub (top tray/lidding film). 80 µ÷250 µ, thermoforming film (bottom try film).
Types of structure: PA/Tie/PA/Tie/PE; PA/Tie/PA/Tie/PP
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Advantages of the asymmetric structure with PA
Heightened superficial glossiness, improving the appearance of the final product. Better mechanical resistance and resistance to superficial scratches. Does not adhere to the welding rod up to a temperature of approximately180 °C. Asymmetric structures represent the greater part of 5-layer structures.
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Disadvantages of the asymmetric structure with PA
The ‘Curling Effect’ can occur due to crystallization (speed and freezing time) and a different level of water vapour absorption on the part of the layer of PA and PE. The Curling Effect can cause problems during the packaging process and have a negative impact on the final consumer of the product. Reduction of the barrier effect because of the humidity and superficial scratches.
Curling phenomenon:
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Device for reducing the Curling Effect Device for reducing the Curling Effect (stretching tub) when asymmetric film is processed with PA on the external level. Importance of the formulation.
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Structure of 5-layer film with a central layer of EVOH The symmetrical structure of 5-layer film PE/Tie/EVOH/Tie/PE. Main applications: laminating film, Bag in Box. The thickness of the layer of EVOH relative to the total thickness depends on its application; the minimum thickness of the layer of EVOH is ultimately dependent on the client’s personal specifications (minimum thickness in μ which guarantees the barrier property of the packaging) Types of structure: PE/Tie/EVOH/Tie/PE; PP/Tie/EVOH/Tie/PE; PE/Tie/EVOH/Tie/PP; PP/Tie/EVOH/Tie/PP; PE/Tie/EVOH/Tie/EVA (sealable / peelable film)
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Structure of film for lamination in a calender The film is typically structured in 5 asymmetric layers with a central barrier layer and an adhesive external layer to be covered with a sheet of PET or PP for the subsequent thermoforming of the bottom tray (the form-fill-and-seal process).
The processing of converting with film can be performed: •In-line (laminating in a calender at the Bandera plant) •Off-line by solventless coating or laminating (in which case a 5-layer film without adhesive external layer is used). Type of barrier structure for lamination in the calender: PE/Tie/EVOH/Tie/EVA (high % VA)* .
(*either high-MFR resin or resin with a low melting point). 16
Bander‘s proposal for a full supply of plant and multilayer blown flat head line for PET foil with a lamination device in the calender.
A group of calenders for coupling.
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Extrusion of PET foil by flat die-head Bandera‘s equipment for the production of PET foil with a flat die-head and lamination in the calender, at thicknesses of 0.18 to 0.6mm. Structure A / B/ A Layer A: 5 + 5% PET Vergine Central layer B: 90% PET flakes shredded and washed by postconsumer
Thanks to twin-screw technology applied to the PET line, it is not necessary to dry out the PET flakes (significant energy saving)
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Bandera’s integrated proposal
+ Bandera‘s proposal for an integrated supply for equipment for blown film in 3.5 and 7 layers and production line for PET foil with lamination in the calender. 19
Examples of vacuum-packed or modified atmosphere packaging protected with multilayered film Top Film or Film Lid Bottom Tray Film
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PET Foil
Top Film Thermoforming Film
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Other examples of the uses of 5-layer film
Sheraton
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Structure of 7-layer symmetrical film The most common structures of 7-layer film are symmetrical structures with a central barrier block of PA/EVOH/PA.
PE/Tie/PA/EVOH/PA/Tie/PE PP/Tie/PA/EVOH/PA/Tie/PE 1. 2.
3.
The central block of PA/EVOH/PA forms a heightened barrier. The presence of PA improves the physical and mechanical properties of the structure. The adhesion takes place between the central barrier block and the PE (or PP).
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7-layer asymmetric structures PA/Tie/PA/EVOH/PA/Tie/PE PA/Tie/PA/EVOH/PA/Tie/PP PA/EVOH/PA/EVOH/PA/Tie/PP Advantages of an internal barrier block and an internal layer of PA: 1. 2. 3. 4.
Improved barrier properties and high glossiness on external layer. Better resistance to temperature on external layer. Increase in the mechanical properties of the film. Reduction of the Curling Effect, due to the combination of the central block and the external layer of PA.
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Advantages of structures with a barrier block of PA/EVOH/PA The adhesion between PA and EVOH (two polar resins) is irreversible.
Furthermore, the middle layer of EVOH is protected (enclosed) by two layers of PA (sandwich structure).
Among other things, these conditions improve the following factors: • • •
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The structure’s resistance to temperature (typically pasteurization/sterilization processes) Better thermal and general mechanical properties (resistance to breaking, perforation and stretching). Better Hot Tack effect. Better response to heat.
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Examples of the uses of 7-layer film
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PE Adhesive PA EVOH PA Adhesive Barrier layer
Adhesive PA EVOH PA
Adhesive PE
Blocked multilayered structure A 13-layer structure made from a block of 7-layer co-extruded blown film. This makes a connection or irreversible merging between the blocked layers. Thickness: 75µ ÷ 350µ.
Common applications: Laminating film: (75 ÷ 150µ) Film Liner / Bag-in-box (75 ÷ 120µ) Thermoforming film (75 ÷ 350µ)
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PE/PP
The structures of symmetrical 9-layer film
Adhesive
PA EVOH PA EVOH
PA Adhesive
PE/PP/Peel
Precise applications with a double block barrier PE/Tie/PA/EVOH/PA/EVOH/PA/Tie/PE PP/Tie/PA/EVOH/PA/EVOH/PA/Tie/PP PE/Tie/PA/EVOH/PA/EVOH/PA/Tie/PP Increase of the barrier effect due to the presence of two layers of EVOH and three layers of PA. The split between the layers of EVOH and PA confers a better barrier property compared with the 7-layer structure of the same total width. The film is less rigid due to the split in the layers of PA.
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Common structures and typical thicknesses of co-extruded blown barrier film, by application: Laminating film: 25 µ ÷ 150 µ of total thickness. Barrier layers from min. 2 µ ÷ 3 µ up to max. 20 µ Total thickness of the blocked layer from 5 µ up to 40 µ •
Converting film: 60 µ ÷ 150 µ of total thickness. Layer of EVOH: 2 µ ÷ 8 µ Layer of PA: 5 µ ÷ 20 µ •
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Thermoforming film: 70 µ ÷ 200 µ: 7 layers; 120 µ ÷ 350 µ: 13 blocked layers Layer of EVOH: 3 µ ÷ 10 µ; Layers of PA: 7 µ ÷ 35 µ.
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Film for generic packaging: 80 µ ÷ 250 µ Layer of EVOH: 5 µ ÷ 10 µ Layer of PA: 10 µ ÷ 30 µ
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Biodegradable and compostable film A new generation of biopolymers made from maize starch, soja starch and potato starch. Principal manufacturers: Basf (Ecovio), Biolice, Biotec, Cereplast, Mirel, Novamont (MaterBi), NatureWorks (PLA), ‌. Regulation EN 13432 (for Europa) e ASTM 6400 & ASTM 6868 (for USA) adhere to the stipulations for biodegradability and compostability.
Main applications: film for bags and sacks, film for sanitaryware, breathable film, mulch film. Typically monolayer film.
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Biodegradable and compostable film National and international laws and standards Care for the atmosphere Ecological movements Critical consumption
bioresin
Question: the price and availability of bioresins on the market. Properties and characteristics of Bioresins as against conventional plastic Conclusion: conventional plastic and bioresins are COMPLEMENTARY products: in short, is it currently conceivable to replace traditional plastic? Oxo(bio) degradable additives: these split the molecule, without forming compost. (?) Disagreement between manufacturers of bioresins and additives about the concept of biodegradability and compostability.
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Bandera: a short introduction With a history of more than 60 years in the development and construction of extruders and extruding equipment, Bandera rates among the foremost Italian companies. The full programme of production currently includes extruders and complete extrusion plants for the extrusion of thermoplastic tubes, profiles, foil, sheet, and of course film. Today, Bandera manufactures the most important and complex parts of its machines (cylinders, screws, die-heads, cooling rings‌) internally, in its own workshops. The portfolio of extrusion lines for blown film comprises:
-Extrusion lines from 1 to 7 layers for film for industrial packaging, -Extrusion lines from 1 to 5 layers for film for agricultural purposes (greenhouse film, silage and silobag, mulch film and silostretch), -Extrusion lines from 1 to three layers for geomembranes up to 8m (smooth and textured).
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Sheraton
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Open Hous plant for HDB/FFS film for Heavy Duty Bag or for Stretch Hood
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Bandera’s single-screw extrudors for coextruded blown film
MODEL Diameter of screw
mm
Relative L/D Capacity with LDPE
Kg/h
35 S
50 AFS
65 AFS
75 AFS
85 AFS
100 AFS
120 AFS
140 AFS
160 AFS
180 AFS
200 AFS
35
50
65
75
85
100
120
140
160
180
200
30
30
30
30
30
30
30
30
30
30
30
45
110
180
250
300
400
500
700
850
1150
1400
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Bandera’s single-screw extruders
Main features Manufactured in Bandera’s workshop, at the heart of CNC work of the latest generation., Bimetallic cylinders: Bernex/Xaloy/Reiloy. Extrusion cylinders lined with Colmonoy. Screw profiles. AC motors with low energy consumption. Direct coupling geared motor with a flexible coupling. Removing rear extrusion screws. Wide range of screen changers, manual type, automatically and continuously.
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Bandera’s die-head extruders Fixed or oscillating mono-layer die-heads, with or without IBC: 3-layer coextrusion die-head, fixed and with IBC: From a diameter of 150 mm (EXPH3 Side Feeding model with IBC) up to 2.300 mm (ACH3I Central Feeding model with IBC). 5-layer coestrusion die-head, fixed and with IBC: From a diameter of 300 mm (EXPH5 Side Feeding model with IBC) up to 2.000 mm (ACH5I Central Feeding Fijo model IBC). 7-layer coextrusion die-head, fixed and with IBC : From a diameter of 380 mm (EXPH7 Side Feeding model with IBC) up to 700 mm (EXPH7 Side Feeding model with IBC).
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Bandera’s extrusion die-head
Oscillating mono-layer Fixed 3-layer coextrusion side feeding central feeding die-head die-head, with IBC. without IBC 37
Extrusion systems for agricultural film The largest 5-layer co-extrusion die-head in the world (Ă˜ 2000mm).
For the production of film for greenhouse covering and silage up to a width of 22 metres. 38
New high-production cooling rings Karat COM2 ring with Dual Lip inserted, and thickness control device.
Karat COM3 patented ring, triple-flow, with an integrated thickness control system.
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New cooling rings Automatic Karat COM3 triple flow ring with integrated thickness control device (patented K-Design EP 08007476 ) Innovative triple-lip cooling system, with heightened regulation, incorporating the Vario Cool thickness control system, in multiple segments, with modulation of the flow of cold air by means of linear actuators.
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Guiding calibration cages Wide range of calibration cages manufactured according to specific user needs and the type of film to be produced. “Scissors type” version with Centro™ with monomer exhausting system.
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Upper take-offs
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Upper take-offs Fixed upper take-offs 600-7500mm wide, for flattening film and gusseted film. Oscillating horizontal upper take-offs up to 4400mm wide, for soft film and gusseted film. In addition to fixed upper take-offs, they are usually used to produce converting film and multi-reel film. 2 and 4 roller versions. Flattening devices made from carbon rolls for the production of technical film and low-thickness film. Wooden slats and gusseting device for the production of medium to high thickness film.
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Automatic winders
Tension control in the middle of the loading cell, with high sensitivity.
Automatic winders by contact at single and double stations.
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Automatic winders For lamination film, film for technical purposes, high speed converting film, barrier film and automatic packaging.
Automatic winders with axial control (centre and gap winding), and contro-rotation, at single and double stations. 45
Automatic winders At Bandera, the safety of operators is paramount. Safe Load System速 allows the machine operator to work in complete safety.
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•Feeding systems and gravimetric batch dosing system of the raw material or continual weight loss. •Reading systems and automatic thickness control (with capacitative and radioisotropic heads). Peripheral devices and accessories •Corona treatment unity for printable film. •Chiller. •Suction systems and removal of waste. •Systems for the elimination of static electricity. •Manipulators for extracting the old reels. •Increase in the automatization of the process. •Control (reduction) of the production costs •Production monitoring (tracking) •Increase in the quality of the final product •Optimization of the industrial production and logistics •General improvement of the safety of the work environment.
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Peripheral devices and accessories •Increase in the automatization of the process. •Control (reduction) of the production costs •Production monitoring (tracking) •Increase in the quality of the final product •Optimization of the industrial production and logistics •General improvement of the safety of the work environment.
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Costruzioni Mecc. LUIGI BANDERA S.p.A. •Developed and built internally at our workshops, using our own technology. •Solid and constant support and technical advice during the sale and post-sale period. •Highly qualified technical service, with a staff comprising mechanical engineers, electricians and specialist technicians. •Remote diagnostic service (Teleservice) via the Internet. •Efficient spare parts service. •Excellence in quality and pricing. •Strong presence. •Customer-orientated.
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From 1943 to the present day‌ 69 years of shared history.
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Thank you for your attention.
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