What Is Paper?
Paper is a thin material produced by pressing together moist fibers,
typically cellulose pulp derived from wood, rags or grasses, and drying
them into flexible sheets.
The modern pulp and paper industry is global, with China leading
production and the United States behind it.
• The word "paper" is etymologically derived from Latin papyrus,
which was the material used by ancient Egyptians to write on before
the advent of paper.
• Paper, and the pulp papermaking process, was said to be developed
in China during the early 2nd century AD, possibly as early as the year
105 A.D., by the Han court eunuch Cai Lun, although the earliest
archaeological fragments of paper derive from the 2nd century BC in
Types of Paper
• Printing papers of wide variety.
• Wrapping papers for the protection of goods and merchandise. This
includes wax and Kraft papers.
• Writing paper suitable for stationery requirements. This includes
ledger, bank, and bond paper.
• Blotting papers containing little or no size.
• Drawing papers usually with rough surfaces used by
artists and designers, including cartridge paper.
• Handmade papers including most decorative papers,
Ingres papers, Japanese paper and tissues, all
characterized by lack of grain direction.
• Specialty papers including cigarette paper, toilet
tissue, and other industrial papers.
Properties of Paper
• Bulk and Density : Decrease in bulk or in other words increase in
density makes the sheet smoother, glossier, less opaque, darker, lower
in strength etc.
• Formation : Formation is an indicator of how uniformly the fibers and
fillers are distributed in the sheet.
• Smoothness : Smoothness of the paper will determine whether or not it
can be successfully printed. Smoothness also gives eye appeal as a
rough paper is unattractive.
• Whiteness : Whiteness is the extent to which paper diffusely reflects
light of all wavelengths throughout the visible spectrum.
Raw Materials And Their Types
Non Fibrous Raw
Fibrous Raw Materials
Fibrous Raw Materials are classified into four parts :
• Paper Pulp : includes ground wood, bleached and unbleached sulfite and sulphate
semi chemical pulps. Blending of various pulps frequently required to impart
proper specifications to end products with maximum yield from pulping materials.
• Reuse Pulp : paper products, such as newspapers and paperboard, are repulped and
mixed with new pulp for paper mill feed stock. This source accounts for 4-6% of
fibrous starting materials.
• Miscellaneous Cellulose Pulp : straw, linen, cotton and rags.
• Specialty Pulp : inorganic fibers such as asbestos and glass.
Non – Fibrous Raw Materials
The paper industry is a good customer of the chemical industry. In
addition to chemicals used in producing the pulp, a large variety of
materials for fillers, sizing, and coatings are required. These materials
are classified into two parts:
• Inorganic Raw Materials : clay, talc, titanium dioxide, zinc sulfide,
calcium carbonate, calcium sulfate, barium sulfate, alum.
• Organic raw Materials : rosin, glue, casein, waxes, glycerol, dyestuffs.
More Info About Raw Materials
• Straws - In India, rice, wheat straw, bagasse and corn straw are used
for paper pulp making. Straw has been reported as suitable for paper
• 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 found
extensively in India, Russia & America.
• Manila - This Fibre occurs in the leaves of a plant of the plantain
family that grows in the Philippines Islands.
• Sisal Hamp - The fibre comes from the leaves of the plant Agave
Sisalana and is used for making rope & twine.
Paper can be produced with a wide variety of properties,
depending on its intended use.
• For representing value: paper money, bank
note, cheque, security , voucher and ticket
• For storing
information: book, notebook, magazine, newspaper, art, letter.
• For personal use: diary, note to remind oneself, etc.; for
temporary personal use: scratch paper
• For communication: between individuals and/or groups of
• For packaging: corrugated box, paper
bag, envelope, wrapping tissue, Charta
emporetica and wallpaper
• For cleaning: toilet paper, handkerchiefs, paper towels, facial
tissue and cat litter
• For construction: papier-mâché, origami, paper
planes, quilling, paper honeycomb, used as a core material
in composite materials, paper engineering, construction
paper and paper clothing
• For other uses: emery paper, sandpaper, blotting paper, litmus
paper, universal indicator paper, paper
chromatography, electrical insulation paper.
Industrial Paper Making Process
-Timber comes from
forests where more trees
are planted than
-Papermakers usually use
only the parts of the tree
that other commercial
industries don't want
such as saw mill waste
and forest thinnings.
-Bark is stripped from the logs by knife, abrasion,
or hydraulic debarker.
-The stripped bark is then used for fuel or as soil
-A hydraulic debarker is a
machine removing bark
from wooden logs by the
use of water under a pressure
of 100 psia or greater.
-Stripped logs are chipped into small pieces by knives
mounted in massive steel wheels (used in chemical
-The chips pass through vibrating screens, whereby
both undersized chips and oversized chips are
Chemical Pulping Process
-Chips are fed into a digester to which chemicals have
been added. The woodchips are then 'cooked' to
-The chips are 'cooked' by heat and pressure in caustic
soda and sulphur.
-The chemical process is energy self-sufficient as
nearly all by-products can be used to fire the pulp mill
Mechanical Pulping Process
- Fiber is produced by forcing debarked logs, and
hot water between enormous rotating steel discs
with teeth that literally tear the wood apart.
- lignin, a material which is sensitive to light and
degrades, and turns brown in sunlight, which
explains why papers made from mechanical pulp
-The special advantages of mechanical pulp are that
it makes the paper opaque and bulky.
The bales of wood pulp or waste paper are
passed into a circular tank containing water.
This has a very powerful agitator at the bottom
which breaks up the bales into small pieces.
Hydrapulpers are fitted with special devices for
removing unwanted contraries such as wire,
plastic, paper clips, staples etc.
• Chemicals can be added to obtain the required
characteristics to the finished paper.
• Dyes are also added, as necessary, to color the
• Dyes fix themselves to the cellulose
fibers and are fast to light and water.
The waste paper merchant collects
the used paper which is then sorted by
hand into different grades. Paper not
suitable for recycling is removed.
The waste paper merchant will then
bale the waste paper ready to be taken
to the paper mill.
• Before printed paper, such as office waste and newspapers,
can be recycled the ink needs to be removed, otherwise it
will be dispersed into the pulp and a dull grey paper would
• There are two main processes for de-inking waste paper these are known as washing and flotation.
Washing : The waste paper is placed into a pulper with large
quantities of water and broken down into a slurry.
Flotation : the waste is made into a slurry and contaminants
removed, Special surfactant chemicals are added which
makes a sticky froth on the top of the pulp.
The stock is pumped through a conicle
machine which consists of a series of
revolving discs. The violent abrasive and
bruising action has the effect of cutting,
opening up and declustering the fibers.
Screening and Cleaning
Pulps contain undesirable fibrous and
non-fibrous materials, which should be
removed before the pulp is made into
paper or board.
Cleaning involves removing small
particles of dirt and grit using rotating
screens and centrifugal cleaners.
• Most modern papermaking machines are based on the principles of
the Fourdrinier Machine, which uses a specially woven plastic fabric mesh
conveyor belt where a slurry of fiber (usually wood or other vegetable
fibers) is drained to create a continuous paper web. After the forming section
the wet web passes through a press section to squeeze out excess water, then
the pressed web passes through a heated drying section.
• The Paper Machine is a very large piece of machinery.
• The machine itself consists of 7 distinct sections. The flow box, wire, press
section, drier section, size press, calendar and reeling up.
Paper machines have four distinct operational sections:
• Forming section, commonly called the wet end, is where the
slurry of fibers is filtered out on a continuous fabric loop to
form a wet web of fiber.
• Press section where the wet fiber web passes between large
rolls loaded under high pressure to squeeze out as much water
• Drying section, where the pressed sheet passes partly around,
in a serpentine manner, a series of steam heated drying
cylinders. Drying removes the water content down to a level
of about 6%, where it will remain at typical indoor
• Calender section where heavy steel rolls smooth the dried
paper. Only one nip is necessary in order to hold the sheet,
which shrinks through the drying section and is held in
tension between the press section (or breaker stack if used)
and the calender. Extra nips give more smoothing but at some
expense to paper strength.
Releases to the Environment
• No manufacturing process converts all of its inputs
into final products. There is always some waste.
• The waste from pulp and paper manufacturing
includes releases to air, land and water, as well as
• In 1991, the pulp and paper industry discharged 2.25
billion tons of waste to the environment .This waste
included about 2.5 million tons of air emissions and
about 13.5 million tons of solid waste , leaving 2.23
billion tons of wastewater. Thus over 99% of the
waste, measured by weight, was wastewater.
Releases to Air
• Carbon dioxide (CO2) results from the complete
combustion of the carbon in organic materials. Combustion
of biomass (wood waste) and fossil fuels generates carbon
dioxide. Carbon dioxide is a greenhouse gas that is
associated with global climate change.
• Chloroform a hazardous air pollutant, is classified as a
probable human carcinogen.
• Hazardous air pollutants (HAPs ) are a group of 189
substances identified in the 1990 Clean Air Act Amendments
because of their toxicity.
• Particulates are small particles that are dispersed into the
atmosphere during combustion.
• Sulfur dioxide and nitrogen oxides emissions result from
the burning of fuel in boilers.
Releases to Land
• Mills generate three types of solid waste: sludge from
wastewater treatment plants, ash from boilers and
miscellaneous solid waste, which includes wood waste,
waste from the chemical recovery system, non-recyclable
• In some cases, recycling-based paper mills produce more
solid waste than do virgin fiber mills.
• Printing and writing paper mills tend to generate the most
sludge, while paperboard mills produce the least.
Releases to Water
• Adsorbable organic halogens (AOX ) measures the
quantity of chlorinated organic compounds in mill effluent
and is an indirect indicator of the quantity of elemental
chlorine present in the bleach plant and the amount of lignin
in the unbleached pulp before It enters the bleach plant.
• Biochemical oxygen demand (BOD) measures the amount
of oxygen that microorganisms consume to degrade the
organic material. Discharging effluent with high levels of
BOD can result in the reduction of dissolved oxygen in
mills’ receiving waters, which may adversely affect fish and
• Chemical oxygen demand (COD) measures the amount of
oxidizable organic matter in the mills’ effluent. It provides a
measure of the performance of the spill prevention and
control programs as well as the quantity of organic waste
1. Air Emissions
There are three control technologies that remove specific
substances from the air emissions of pulp and paper mills.
A)Electrostatic precipitators physically remove fine
B)Scrubbers chemically transform gaseous sulfur dioxide,
chlorine and chlorine dioxide so that they stay in the
scrubber’s chemical solution.
C)Mills route combustible gases, including total reduced
sulfur compounds, to the chemical recovery system.
2. Solid waste Disposal
• Mills send more than 70% of their solid waste to landfills,
most of which are company-owned.
• Residue from recycled-paper based mills is usually
landfilled in a secure, lined facility. The amount of residue
generated by a mill is partly a function of the quantity of
contaminants in the incoming recovered paper.
• Some manufacturers of 100% recycled paperboard, for
example, use the fibrous residue from their process in the
middle layers of their multi-ply sheet.
• Many recycled paper manufacturers are trying to find ways
to separate the materials in mill residue into products that
can be beneficially reused.
3. Effluent Treatment
• The wastewater from all but one mill in the United States
undergoes two stages of treatment before it is discharged.
• Primary treatment removes suspended matter in the effluent
.These wastes, which consist mainly of bark particles, fiber
debris, filler and coating materials, leave the system as
• Secondary treatment systems use microorganisms to convert
the dissolved organic waste in the effluent into a more
harmless form. These systems generally remove 90-95% of
the BOD in the effluent. Although primarily designed to
remove BOD, secondary treatment also reduces the loading
of COD and AOX. Effluent discharged from a well - run
secondary treatment system is not acutely toxic to aquatic
The digital revolution has been beneficial to the paper
industry on the whole. With every new technological
advance, the amount of information has multiplied, and
the volume of paper has risen as well. Paper remains the
best, most cost-effective, and most prevalent way to
view and store many kinds of information, from novels
to transaction records to catalogues.
Nonetheless, many technology advances in the areas of
printing, distribution, display and storage have had an
enormous effect on the volumes of different grades of
Further, every major paper application is developing
along a unique path, affected by core technology
developments, economic factors favoring or opposing
the use of paper, and cultural issues promoting or
inhibiting change. Some applications actually offer
opportunities for increased use of paper, and other cause
changes in demand for different grades of paper.
Instead of using flat paper for photo printing (which can't
change its reflective properties), the researchers are creating a
new kind of paper with specular micro-geometry. In other
words, it looks like regular flat paper to your eye, but its
surface is actually covered in thousands of microscopic hills
and valleys. We can print onto those tiny shapes to control the
way the light reflects from different angles. The result is that
the object in a photo would reflect light the same way as the
object would in real life. Or so your eyes would perceive.
So in our presentation we have covered the different types of paper, its
properties, raw materials used , paper processing and manufacturing, its
future aspects & environmental aspects.
• Dryden’s Outline of Chemical Technology