History of Paper

The word paper derives from the word 'papyrus' and is a substance composed
of fibres interlaced into a compact web, which can then be macerated into
pulp, dried and pressed. About 5,000 years ago, Egyptians created "sheets"
of papyrus by harvesting, peeling and slicing the plant into strips. The
strips were then layered, pounded together and smoothed to make a flat,
uniform sheet. No major changes in writing materials were to come for about
3,000 years. The person credited with inventing paper is a Chinese man named
Ts'ai Lun. He took the inner bark of a mulberry tree and bamboo fibers,
mixed them with water, and pounded them with a wooden tool. He then poured
this mixture onto a flat piece of coarsely woven cloth and let the water
drain through, leaving only the fibers on the cloth. Once dry, Ts'ai Lun
discovered that he had created a quality writing surface that was relatively
easy to make and lightweight. This knowledge of papermaking was used in
China before word was passed along to Korea, Samarkand, Baghdad, and
Damascus.
By the 10th century, Arabians were substituting linen fibers for wood and
bamboo, creating a finer sheet of paper. Although paper was of fairly high
quality, the only way to reproduce written work was by hand, a painstaking
process.
By the 12th century, papermaking reached Europe. In 1448, Johannes
Gutenberg, a German, was credited with inventing the printing press. (It is
believed that moveable type was actually invented hundreds of years earlier
in Asia.) Books and other important documents could now be reproduced
quickly. This method of printing in large quantities led to a rapid increase
in the demand for paper.
Today, paper includes a wide range of products with very different
applications: communication, cultural, educational, artistic, hygienic,
sanitary, as well as for storage and transportation of all kinds of goods.
It is almost impossible to imagine a life without paper. We offer diffrerent
kinds of paper and paper products like chromo paper, cast coated paper, art
paper and coated papers.
Paper is an essential part of our lives and satisfies many human needs. We
use it to store and communicate information (newspapers, books, documents
and writing paper), for cultural and artistic purposes, to transport and
protect food (packaging, sacks, tetra packs), for personal hygiene (tissues,
napkins, nappies, etc.) and in medicine (hospital uses).
Paper Making Process

 |
 |
Raw materials
Paper is made of all sort of things you can think of -
Soft Wood - Like spruce & pine which have a long fibre
Hard Wood - Short Fibre. Not very suitable for paper making. Gives
trouble in barking and chipping. Eucalyptus, Acacia, Albizzia & wattle
trees are more suitable hard wood trees for paper making and do have a very
high rate of growth
Grasses - Several types of long grasses like bamboo sabai grass,
sarkanda etc. are used
Straws - In India rice, wheat straw, bagasse and corn straw are used
for paper pulp making. Straw has been reported as suitable for paper making
Cotton Linters - It is a seed hair from cotton plant after
extracting cotton. Only small proportion of raw cotton in form of short
fibre linters comes directly to paper mills Cotton Rags - This gives more
strength in paper or paper board
Linen - Linen fibre is derived from the bast tissue of the stem of
the flax plant, cultivated extensively in USA, Russia, Hungary, France,
Belgium & Ireland
Hemp - It comes to paper maker in the form of spinning waste, twine,
cordage, ropes etc. Hemp is the bast tissue of an annual shrub growth
extensively found in India, Russia & America
Manila - Fibre occurs in the leaves of a plant of the plantain
family that grows in the Phillipines Islands
Sisal Hamp - The fibre comes from the leaves of the plant Agave
Sisalana and is used for making rope & twine
Waste Paper - The demand of waste paper for manufacturing of paper
is increasing every day. Utilization of this would reduce load on demand of
fresh fibres. About 80% of the waste paper is used in the manufacture of
paper boards. Small scale units depend almost entirely on waste paper as raw
material.

Pulping
It is obtained by removing lignin and other impurities from the wood &
other raw materials used by a cooking process (Lignin is the glue that holds
the fibers of the wood in three form). The cooking process requires wood
bamboo or other raw materials chips. The chips are loaded into a digester
and a cooking liquor is added. Then by pressure cooking, the wood bamboo or
other fibers are separated from other unwanted ingredients. Either batch
digester or continuous digesters are used in cooking.
The chips and liquor are mixed as the chips are pumped to the top of the
digester. The top section of the digester is pressurized to 160 psi and
more. As the chip mass passes downward the cooking liquor penetrates the
chip. After about 45 minutes or more as per raw material the chips have to
be passed through the impregnation zone where hot liquor (340 degree F) is
circulated through the chips for heating. The actual pulping occurs at 355
degree F in about 90 minutes, a period known as the cooking period. After
passing through the cooking zone, the chips (which have not become pulp) are
washed with weak liquor from washing stages that follow.
Within the chemical process there are two types -
» Sulphate Process "(Alkaline process)"
» Sulphate Process "(Alkaline process)"
Some hard woods may be dissolved with difficulty by the sulphite process.
On the other hand, the sulphate process most of the chemicals are recovered
and reused.

Bleaching
Although cellulose fiber is white in colour, due to residual lignin traces
remaining on the fibers, the pulp appears creamish. Therefore, to
manufacture white paper we need to remove yellowness without physically or
chemically damaging the fiber, with improvement in various properties. So
the main objectives of bleaching the pulp, can be set out as follows;
Although cellulose fiber is white in colour, due to residual lignin traces
remaining on the fibers, the pulp appears creamish. Therefore, to
manufacture white paper we need to remove yellowness without physically or
chemically damaging the fiber, with improvement in various properties. So
the main objectives of bleaching the pulp, can be set out as follows.
Bleaching for brightness improvement should also help to keep the pulp
stable without turning yellow or lose strength or reduce brilliance - due to
aging.
To lower viscosity of the pulp for optimum flow, during subsequent
operations.
Bleaching also should help to reduce the fiber bundles, shives and bark
fragments. Bleaching should be done with minimum mechanical action of
fibers, while dissolving lignin and other unwanted residuals.
Bleaching Pulp is normally done in a step-wise sequence using different
chemicals and process conditions at each stage, with washing in between
stages.

Additives
Additives are added to paper pulp. Addition of fillers like clay and
calcium carbonate is very common and besides acting as fillers they add
brightness to the paper. These additives must be finely ground. Additives
like dyes and pigments are also added. Other fillers are Titanium Dioxide,
Barium Sulphate and Zinc Sulphide

Removing Water
Removing water is the next important stage. For this the pulp is passed
through a rapidly moving wire mesh called fourdriner. The objective is to
recover 93 to 95% of the water in the finished paper.
As the paper flows along the wire mesh and water is drained along the way,
a dandy roller near the end helps to smooth out the paper. The dandy roller
improves the formation of the paper web by application of pressure. When the
paper reaches the end of the wire mesh, it is transferred to a felt blanket
which conveys it through many steam heated driers to remove the excess
moisture. In the process the paper gets some glaze like coating also. Then
it is made to pass through a series of calendar stacks. The calendars are
series of polished iron rollers stacked one on top of the other, through
which the finished paper will pass to smoothen down.
The next step is rewinding on a metal or fibre core. The last stages after
this are sheeting, packing & testing.