How Paper is Made

Page 1

How

Paper is

Made


THE

SOURCE

This number of trees is used in paper making worldwide Equating to 35% of all trees cut down per year

=1 Billion

85% of trees used to make paper are coniferous

Hardwoods such as oaks and maple make up the rest of that percentage

15%

85%


1

ofTon

Recycled Paper

However the fibres from the recycled paper break up over time, which means that the paper can only be used as low quality products such as toilet roll.

= Recycled paper makes up a third of all sources used.

Recycled Paper


De-Barking Any excess bark is collected and used for a fuel process later on. Bark is stripped from the logs in a revolving drum containing blades; leaving a smooth log.


The smooth logs are chipped into small pieces, by using knives mounted in huge steel wheels The chips are then passed through vibrating screens where dust and misshapen chips are discarded

Chipping


Chemical Pulping Chips are fed into a digester, then cooked by heat and pressure in caustc soda and sulphur. This removes the lignin; resulting in a better quality paper that doesn始t discolour over time.

?

What is Lignin Lignin is an organic substance binding the cells, fibres and vessels within the wood.


De-Inking

Recycled Paper is treated using the chemical process. After this it goes through De-Inking.

Debarked logs along with hot water, are forced between huge rolling discs that tear the wood apart.

Paper from this process is mainly used for newspaper as it is low quality

Mechanical Pulping


Screening Screening is the process that seperates the pulp from the impurities

Inlet

The rejected material is large knots and other debris There are usually multiple screens set up at any one time, this ensures that no good fibre is rejected and that no impurtites get through Rejects

Accepts


The untreated wood pulp has a brownish colour; so it has to be treated with bleach before it can be used to make white paper. Chlorine based methods are usually used as it has less of an enviromental impact compared to other methods.

Bleaching


The

Fourdrinier Process

The Wire mesh can be 20 foot wide and travel at speeds of up to 60 mph

W

He

The put

The Fourdrinier machine is made up of 4 main sections

1

Wet

3

End

2Wet

Press

Section

Dryer

4

Calendering

The Slice

It is fed down here a revolving wire m


Wet

eadBox

Wire Mesh

End

e pulp mixture is in here.

e onto mesh.

As it passes along the mesh, the paper is formed and a percentage of excess the water drains out.


Fourdrinier machines are

HUG E

Wet Press

Wet End to Drying Section

can be the same size as a

FOOTBALL PITCH

Felts

These support the paper and also aid in water removal by absorption

Rollers

The paper is then carried though a ser rollers under high pr squeeze the water o


ries of ressure to out .

Paper treatment

This is where sizing and adding characteristics to the paper will take place. e.g glossy, silky or matte

Steam Heated rollers

These rollers cause further water removal through evaporation

Section

Dryer


Calendering Section

Calender

The paper passes through a calender roll that smooths out the surface

If the degre chang coatin


e paper has a coating the ee of calendering will ge the characteristics of the ng.

Finishing The paper is then spooled into huge rolls where it can be cut into various sizes or converted into paper products.


Tanya Baxter & Louis Byrne


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