Hello!
Today we will talk about the production of an item that we use every day.
This is paper.
Probably, few thought about how it is done?
In this video, we will show the entire production process from start to finish.
High-quality paper is made from wood obtained from trees grown on special plantations.
Forestry specialists, with expert knowledge, are responsible for harvesting timber, while
minimizing the impact on the environment.
All wood is divided into soft and hard.
Hardwoods such as birch, poplar and eucalyptus are used to make paper.
Softwoods include conifers such as spruce, fir and pine.
The wood fibers of coniferous trees are longer than those of hardwoods and therefore the
paper from them is more durable.
The process of paper production begins with a wood warehouse, where all the wood is delivered.
Hardwood roundwood - oak, maple, ash is stacked separately from softwood - pine and spruce.
Since different species have different lengths of wood fibers, this must be taken into account
later in the wood pulp pulping process.
In addition to logs, the largest source of wood chips for paper production is waste from
wood processing plants.
From the warehouse, the logs enter a long conveyor belt, along which they are directed
to the debarking drum, which removes the bark from the logs.
Then, the logs, peeled from the bark, are fed into an industrial chipper, where they
are crushed in a matter of seconds into chips measuring 2 and a half centimeters.
Chips of non-standard size are removed.
A uniform chip size is important for the subsequent pulping process as it increases the yield
and quality of the wood fiber.
The sifted fine chips and sawdust are removed, and together with the bark from the debarking
drum, are sent to the energy boiler.
The resulting electricity from their combustion goes to the needs of the factory.
It covers 40% of the energy costs of the enterprise.
The wood chips are then transported by truck to the pulp mill.
Chips are still divided into hardwoods and softwoods.
The wood chips, together with white liquor, are conveyed along a conveyor belt to a continuous
digester, where they are boiled in an acid solution.
This is necessary to dissolve the lignin and separate the plant fibers.
During the cooking process, the white liquor is heated to 170 degrees Celsius and dissolves
the lignin that holds the wood fibers together.
After a few hours, the lignin dissolves and the fibers are washed to remove the acidic
solution and pulp.
To do this, pulp from the digester, along with waste chemicals, now called black liquor,
is sent to the washing zone.
Here, uncooked wood, such as knots, is washed out of the pulp.
The resulting mass is called technical cellulose.
Lignin is considered an undesirable component of paper because it contributes to its yellowing.
To avoid this, significant efforts are required to remove it from the wood pulp.
To remove lignin residues and make the pulp whiter, it is bleached.
The pulp is now soft and fibrous.
Such bleached pulp will be used to make white paper that will not turn yellow with age.
Bleaching takes place in several steps as it changes the fibers from their natural brown
color to white.
Previously, this bleaching was done with chlorine, which destroyed the lignin macromolecules.
But in the early 1980s, information appeared about the formation of extremely dangerous
substances - dioxins - in the process of chlorine bleaching.
Currently, bleaching technology is completely chlorine-free.
Oxygen, ozone, hydrogen peroxide and more are used.
Thus, the brown wood chips that ended up in the pulp mill turned into soft white pulp,
the main ingredient for making paper.
The processed pulp can now be dried and sent to other paper mills, which may either not
have their own paper stock or may need a special type of pulp to give the paper special properties.
Whether the pulp is produced locally or purchased from the market, it is mixed with water in
the paper mill.
The pulp thus obtained is cleaned by passing it through a series of rotating and stationary
blades, which give the fibers varying degrees of cleaning.
This process is called fibrillation.
With it, the fibers first of all split at the ends, mainly where they were cut.
Such fibrillated fibers bond more tightly to adjacent fibers, resulting in a stronger
paper.
The wood fibers themselves, if left untreated, would produce a rough textured and uneven
heavy paper.
Mineral fillers such as kaolin, chalk and talc are added to the refining to increase
whiteness, smoothness, softness and opacity, as well as improve the printing properties
of paper.
Aniline dyes are added to give color and increase whiteness.
To make paper suitable for writing and to give it hydrophobic properties, rosin glue,
paraffin emulsion, alumina and other substances that promote sticking together are introduced
into the paper mass - this is the so-called sizing.
One of the most important ingredients in papermaking is water.
It is not for nothing that pulp and paper mills are usually located on the banks of
large rivers, because then it becomes possible to use the rivers to melt wood, which is the
main raw material for production.
It takes about one hundred liters of fresh water to produce one kilogram of paper.
Modern wastewater treatment plants and closed water circulation systems on the paper production
line allow more than 90% of this water to be recycled.
The finished paper pulp with a concentration of 3-4% is pumped from the mixing section
to the mixing pool, from where it enters the paper machine.
This machine is the heart of the paper mill.
Like a giant dryer, it extracts water from paper pulp to produce a dry sheet of paper.
The production processes taking place in it turn the pulp into an ideal grade of paper.
The machine is equipped with a large capacity headbox where the cellulose solution is injected
under high pressure.
In the tank there is a constant mixing of the solution to maintain a homogeneous state
of the paper pulp throughout the volume.
Here the ebb, dehydration and compaction of the paper web take place.
The machine is made according to the principle of sequentially installed continuously operating
sections: mesh, press, drying and finishing.
The solution falls on a moving flat wire mesh.
At this stage, it is 99.5% water and 0.5% fiber.
As the mixture passes through the rotating mesh, the water simply flows off by gravity.
The quality of the material produced depends on the synchronism of the speeds of the mesh
and the outflow of the suspension.
The mesh table ends with a device called a suction couch roll.
Vacuum is maintained in its chamber, which makes it possible to effectively suck out
moisture.
After the couch roll, the paper web is still 85% water.
The paper former quickly removes excess water from the machine, this immobilizes the pulp
inside in a few milliseconds.
Now it turns into a continuous sheet of paper.
The speed of the paper web is 1000 meters per minute or 60 kilometers per hour.
Sheet shedding is a filtration process in which, as water is removed, a fibrous layer
is formed.
After passing through the register part of the grid table, a sheet with a mass concentration
of about 3% is formed.
When such values are reached, the “mirror of the bay” ends and the concepts of “paper,
paper web” and its dryness are introduced.
During the pressing phase, the web is still wet and brittle, but already exhibiting its
most important sheet properties.
The delicate paper web is fed into the press section by continuously rotating wet felt
rollers.
The press part usually consists of two or three twin-shaft presses.
The upper shaft is made of granite, the lower one is metal lined with rubber.
Between them, together with the paper web, the cloth moves, protecting the surface of
the wet paper from damage.
After successive passage of the press section, the dryness of the paper is 30-40%.
In this section of the machine, not only dewatering takes place, but also the web is compacted.
This increases the area of contact and adhesion between the fibers.
In addition, paper properties change: strength increases, porosity decreases, transparency
increases, etc.
Of the total volume of removed water, about 95% falls on the wire part, 3-4% on the press
part, and the rest on the drying part.
The longer part of the paper machine is the dryer part.
This section of the machine consists of 2 rows of successively staggered cylinders covered
by a drying cloth.
The device of the drying cylinder is a hollow cylindrical container, heated from the inside
with steam.
Depending on the type of paper produced, the cylinder temperature ranges from 80 to 115
°C. During the drying process, up to 2.5 liters of moisture is removed from 1 kg of
paper, which is 60-80 times less than on the wire and press parts of the machine.
Each process is under continuous control, which ensures its production stability.
The paper passes through a machine calender where two finely polished steel cylinders
must accurately determine the required web thickness and width.
The main characteristics of the calender are the number of rollers, their length, diameter
and relative position.
It is installed between the drying part and the reel and consists of 5-8 horizontally
arranged shafts.
Calenders are also used to make the paper surface smooth and glossy.
The paper web then passes through a series of sizing and coating presses where sizing
and application of various coatings consisting of starch and dyes takes place.
The coating gives a very smooth, bright surface with the highest print quality.
It is applied to the surface using a film press.
The coating dye is sprayed onto an elastic roller, which then transfers the coating film
onto the paper web.
After each coating process, the surface is dried by infrared heating panels and drying
cylinders.
On the reel, the paper is formed into rolls by weight or diameter.
It is wound on a series of steel cores that are pressed against the coil.
A constant down pressure is maintained between the drum and spool, allowing the resulting
friction to rotate the spool.
This ensures that the paper is wound with the correct tension on each such core.
Every hour the paper line creates a giant reel containing 80 kilometers of paper sheet
8.5 meters wide and weighing 120 tons.
Paper machine operators carefully check every aspect of the quality of the base paper: its
thickness, opacity and smoothness.
They must make sure that the products exactly meet the declared characteristics.
Only then is permission given to the robot truck to transport the giant roll for further
processing.
Also, each batch of paper is controlled on the coating and finishing lines.
For example, the paper from this giant spool can be sold in both glossy and matte finishes
and comes in both natural and bright white.
Now the paper has all the characteristics necessary for its use, except for one last
detail - its size.
Large rolls are transported to the slitter rewinder.
It is designed for longitudinal cutting of paper web.
The machine consists of a feeding unit, on which
a raw material bobbin is mounted by means of a mechanical or pneumatic shaft.
Through the intermediate shafts, the paper web enters the cutting unit, which consists
of cylindrical and circular knives.
Rotating blades cut the roll into several narrow rolls, which are wound onto cores after
cutting.
Then several rolls are simultaneously fed into
the cutting drum mechanism.
The guillotine, placed on a rotating drum, evenly cuts the material into sheets of equal
size.
The cut sheets are stacked on pallets.
At the final stage, whether the paper has been cut into sheets for sheetfed printing
or left on a roll for web offset printing, its final destination is the same - a
packaging line and a finished product warehouse.
Each roll of paper is wrapped in kraft paper to avoid damage in transit.
Each pallet of finished paper sheets is shrink-wrapped or paper-wrapped for delivery to the customer.
Each batch of both sheets and rolls is marked with the trade mark and batch number.
Now it only remains to send the products to the consumer.
That's all.
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