How paper is made from wood. Making paper at home Modern paper making for children

Paper is one of the most important human inventions, allowing high-quality exchange of information. It is used in various sectors of the national economy.

Particular attention should be paid to school notebooks, which are a necessary element in the training of every person. You can find out how to choose the right products on the website www.masteroffice.com.ua/tetradi-shkolnye/.

Receiving paper

Paper is the main component of any notebook. Therefore, the production of such products begins with the receipt of high-quality blanks. This process can be described in the following sequential steps:

• wood chopping. For such purposes, only wood without bark is used. Therefore, it is first removed from the trunks. After this, special mechanisms crush the material;
• cooking. Notebook paper is of high quality. To obtain such cellulose, wood is exposed to various chemicals. Before this, the crushed material is carefully sorted and sorted. After this, the pulp is cooked in various acids;
• cooking. When all the components are prepared, several types of glue and various resins are added to them. To give paper White color, kaolin is also added to the solution. After this, the mixture is fed to special machines, where it is dried and squeezed. Paper formation is carried out by special rolling machines.

Manufacturing technology

Notebooks are a small resemblance to a book, only with a small number of sheets. Today there are many varieties of such products on the market. But all of it is made using approximately the same technology. This process can be broken down into several steps:

• seal. This stage involves the use of special printing machines. Please note that it is important not only to print the inner sheets, but also to pre-design the cover. Therefore, much attention is paid to this step. All operations are performed separately on large sheets. After printing, they are cut into specific blanks;
• fastening This process can be carried out according to various technologies. The simplest option is to fasten the sheets with paper clips. The machine simply punches through a stack of paper and bends the wire. But today, very often, rough notebooks are stitched with peculiar springs.

Making notebooks is a complex and lengthy process that requires special equipment and skills to work with it.

Paper is one of the most important inventions of mankind. It’s hard to imagine any sphere without it human activity. The Chinese were the first to make paper in 105 AD. e. Its production technologies have been improved over the centuries. Today it is a multi-stage, highly mechanized process.

Paper grades

Modern production paper makes it possible to obtain many varieties of it. According to the method of application, they are distinguished:

• printing paper;
• cardboard and packaging varieties;
• technical;
• sanitary and hygienic;
• printing.

Types of paper for printing are divided into:

• offset, it is of the highest quality;
• newspaper- contains fibrous impurities;
• coated– with a special coating for glossy magazines;
• office– stands out for its resistance to mechanical damage;
• document paper– with watermarks as protection;
• designer– for business cards;
• packaging;
• self-copying and self-adhesive.

The main indicators of paper quality include:

• its thickness;
• surface porosity;
• degree of opacity;
• smoothness, especially for printing plates;
• strength, it is important for all types of paper.

Main raw material component

The raw material for making paper is cellulose, which is a natural polymer from the class of carbohydrates with a large molecular weight. A high degree of polymerization indicates the length of macromolecules and their mechanical strength. Due to their linear structure, they are flexible and elastic. Intertwined with each other, macromolecules form a fibrous material that swells when exposed to water.

Types of raw materials

Used as a raw material for the production of fibrous materials natural materials- various types of wood, as well as recyclable materials, which constitute waste from various industries.

Pine and spruce trees produce long-fiber cellulose, which can be used to make paper with high strength.

Hardwood. Birch and aspen wood has shorter fibers with lower mechanical strength. Their advantage is the rapid renewability of resources.

Cereal stems, annual plants. The short length of cellulose fibers of corn or cane is compensated by the easy renewability of the raw material.

Waste from cotton and textile production produce long fibers with high mechanical properties.

Waste paper mixed with wood and other waste and used in the production of certain types of paper, such as cardboard. The use of recycled materials helps reduce deforestation. The share of recycled waste paper in paper production is gradually increasing.

Synthetic fibers have recently been used in paper production, which will reduce its cost and save natural resources.

Process stages

Production is carried out at pulp and paper mills. Paper making involves several stages.

Stage 1– initial degree of wood preparation. It includes:

• clearing tree trunks of bark;
• sawing into small bars;
• grinding them to obtain wood pulp.

At stage 2 wood pulp is subjected to high-temperature treatment with acids. It is boiled until a liquid mixture of cellulose fibers is obtained. At the same time, it is bleached and acquires mechanical strength. Then the semi-finished product can be sent:

• on further processing;
• for sale in compressed form.

At the next stage add to the mixture:

• a portion of unprocessed wood pulp or recycled materials;
• large volume of water;
• various additives in the form of resin, glue, special substances, dyes, depending on the purpose of the product.

The paper suspension, in which almost 99% is water, is filtered, cleared of impurities and fed to the paper machine.

Forming of paper web

The mixture falls on a mesh metal mesh, moving along which it loses some of the water. The fibers are arranged along the movement of the mesh and intertwine, forming a paper web. The following manipulations consist of pressing and drying it:

• passing through cylindrical presses, the paper web gives off moisture and becomes more and more compact;
• after passing through the drying part, only 8% water remains in the base;
• Having passed between the calenders, the canvas is wound into a large roll and subjected to cutting.

Before getting onto the calenders, the base is coated. It is coated with an aqueous suspension consisting of adhesive and pigment additives, giving it smoothness and high printing qualities.

The pulp and paper industry is developed in countries where there are large tracts of forest. Every year the need for more and more paper is growing. Although the cutting down of trees during timber harvesting is accompanied by the planting of new ones, forest areas are decreasing over time. That is why the collection of waste paper and its use is so important.

Production of paper from wood. The most economical way to obtain wood pulp is mechanical: at a wood processing plant, timber is crushed into crumbs, which are mixed with water. Paper made from such cellulose is fragile and is most often used in the production of, for example, newspapers.

Paper making machine

This is a continuous multi-sectional unit that produces paper and some types of cardboard from a highly diluted fibrous suspension with water.

There are 2 main types of paper: flat mesh (table paper),
used to produce the main types of paper, and round mesh (cylindrical) ones, on which a limited range of paper and cardboard is produced. These types have various devices for releasing the paper mass onto the paper mesh and casting the paper web; the design of the remaining components, as well as the technology and paper manufacturing process are similar (with the exception of the dry forming machine).

In Fig. Figure 2 shows a diagram of a flat mesh paper pulp, which includes, along with the equipment for the paper pulp itself, auxiliary equipment intended for preparing the paper pulp before feeding it onto the mesh. Kinds

auxiliary equipment and its design are extremely diverse.

Ready paper pulp concentration approx. With the help of pumps, 3-4% is supplied from the pulp preparation department to the machine pool, from where it is supplied to the paper pulp. By constantly mixing the mass in the machine pool, the degree of grinding and concentration of the mass are equalized throughout the entire volume. It is first diluted with recycled water (from dewatering paper pulp on a paper mesh to a concentration of 0.1 - 1.5%) and passed through cleaning equipment (knockers, centricliners, centriscreens, etc.), where various foreign substances are removed inclusions and particles of mineral and fibrous origin. The paper pulp comes from the cleaning equipment and the head box, which ensures the flow of the pulp at a certain speed and the same thickness of the jet over the entire width of the mesh.

Paper foam consists of the following foam parts: mesh foam, where a sheet of paper is continuously formed from a diluted suspension and the first part of excess water is removed from it; the press room, where the paper web is dewatered and compacted; drying room, in which the moisture remaining in the paper web is removed; finishing, where the canvas undergoes the necessary processing to give gloss, density, smoothness and is wound into rolls.

The mesh part is an endless mesh (woven from threads of various copper alloys or synthetic materials). The mesh is driven from the couch shaft. On new machines with vacuum transfer devices, the drive shaft of the mesh is also driven. To prevent the paper pulp from flowing down, limits and rulers are installed along the edges of the mesh. Dewatering of the paper pulp and formation of the paper web occurs due to the free flow and suction action of the register rollers. To obtain a more uniform paper web in the longitudinal and transverse directions at a machine speed of no more than 300 m/min, the register part is sometimes subjected to shaking in the transverse direction. Further dewatering occurs over suction boxes under the action of a vacuum created by special vacuum pumps. When producing high-grade papers, a light leveling roller (eguter) is often installed above them. It also serves for applying water marks to paper. that's how it is. After this, the paper web still contains a relatively large amount of moisture (88-90%), to remove which the mesh, together with the paper web, passes over a couch roll (on low-speed machines, a couch press), which has from one to three suction chambers. Couch shaft is a perforated hollow cylinder made of bronze alloy or stainless steel (the perforation area is approximately 25% of the shaft surface). Inside the housing is a stationary vacuum chamber with graphite seals that are pneumatically pressed against the inner surface of the cylinder. The vacuum chamber is connected to a continuously operating vacuum pump, the Couch roll completes the formation and dewatering (to a dryness of 18-22%) of the paper web on the B. m mesh.

Further dewatering occurs in the press part by mechanical squeezing under the influence of pressure and vacuum by passing the web through several (2-3, less often 4-5) roller presses located in series (often the first and the first press are combined into a double press). At the same time, the bulk density, strength properties, and transparency increase, and the porosity and absorbency of the paper decrease. Pressing is carried out between woolen cloths, which protect the still weak paper from destruction, absorb the pressed moisture and at the same time transport the canvas. Each press has its own felt. On all new high-speed presses, the lower press shafts are made perforated (like couch shafts). They are covered with special rubber, which improves dehydration and increases service life. On some paper machines, instead of lower suction rolls, rolls with special ones are installed. grooved corrugation (grooves). On powerful presses, the lower shafts of the first and second presses are made with suction (similar to a couch shaft). Often, in addition to presses with felts, smoothing (or offset) presses without felts are also installed to compact the paper and make it smooth. Then the paper sheet with a dryness of up to 45% enters the drying section.

The drying part (the largest in length) consists of rotating cylinders, heated from the inside by steam and usually arranged in 2 rows in a checkerboard pattern. The canvas is pressed against the heated surface of the cylinders using felts, which improve heat transfer and prevent warping and wrinkling of the paper surface during drying. The upper and lower rows of drying cylinders have separate felts, with one felt covering several cylinders at once (a group of drying cylinders). The paper web moves from the upper cylinder to the lower one, then to the adjacent upper one, etc. In this case, the paper is dried to a residual moisture content of 5-7%. On a modern paper press, a double-roll sizing press is usually placed in the second half of the drying part for surface sizing of paper and application of the surface layer. The drying part of some paper machines is equipped with automatic regulators for the supply of steam to the cylinders, devices for automatically threading the paper web onto the drying cylinders, etc. The steam is collected by a floor hood located above the entire drying part of the paper machine, and then removed by exhaust fans to the outside. The heat is used in heaters and heat exchangers.

The finishing part is a calender consisting of 5-10 bleached cast iron shafts located one above the other. Previously, the paper is cooled and somewhat moistened on a refrigeration cylinder (through the hollow necks of which cold water is supplied and discharged) to give it greater elasticity and softness. When moving between the shafts from top to bottom, the web becomes smoother, thickens and evens out in thickness. Then the paper is wound with an endless tape into rolls on a reel (a forcedly rotating cylinder in which the roller with the paper wound on it is pressed). To moisten the paper when finishing it on supercalenders (to obtain paper with increased smoothness, gloss and bulk), a humidifier is installed above the reel. Next, the roll is cut on a longitudinal slitting machine into the required formats. At the same time, the paper is sorted, and the breaks that occur during its production are glued together. When producing paper in sheets, the rolls for cutting are fed to the self-cutting machine.

Paper may also have a large number of different equipment necessary to ensure its continuous operation, and automatic devices that regulate technology. options. For each type of paper, technically and economically justified width and operating speed of the paper making machine are established.

The narrowest paper-making machines (with a paper web width of 1.6-4.1 m) are designed for the production of the thinnest condenser papers, special. technical, high-quality photo and document papers. Wide paper-making machines (over 6 m) are used to produce newsprint and sack paper. The operating speed of the paper machine for the production of condenser paper is 40-150 m/min, newsprint - up to 850 m/min, tissue paper - approx. 1000 m/min or more. The productivity of a paper-making machine producing capacitor paper with a thickness of 4-12 microns is 1-4 tons/day, newsprint - 330-500 tons/day or more. The length of the machine for producing newsprint reaches 115 m, the weight is approx. 3500 t, height dep. parts up to 15 m, power of all electric motors (including equipment for preparing paper pulp) approx. 30,000 ket. Drive dept. B. m. sections are carried out by engines direct current. Within 1 hour, such a paper-making machine consumes up to 45 tons of steam. Do I regulate automatic devices? processes of casting and drying paper at high speeds. The high level of equipment with automatic devices, the precision of adjustment and execution of the paper-making machine make it possible to reduce the number of workers directly servicing it to 3-8 people. Many new paper machine designs are being developed, differing mainly in the methods of forming the paper web. In paper mills of the inverform type (England), the paper web is cast and molded between two meshes—lower and upper (Fig. 3). The paper pulp from the headbox is fed into the gripper between the lower and upper meshes, which creates pressure on the fluid flow. Some of the water passes down through the deposited layer of fiber on the lower mesh, and the rest is removed through the upper mesh. Water is removed from the inner surface of the mesh with a scraper equipped with a knife made of plastic material and a drainage tray. Further dehydration is carried out using conventional and “inverted” suction boxes at a vacuum not exceeding 12 kn/m2 (0.12 kgf/cmg). A press is installed behind the suction boxes and the squeezed water is sucked out through the upper mesh with a scraper. When producing multilayer paper, there are several top grids (according to the number of layers). Water is practically removed only through the upper meshes along scrapers and inverted suction boxes.

In vertiform paper, the paper web is dewatered on both sides between two vertically moving meshes using scrapers and suction boxes, which ensures the deposition of fibers of the same fraction on both sides of the paper web. In this case, short and thin fibers are deposited first, resulting in the formation of a surface most suitable for printing, and large fibers appear in the middle of the sheet, which increases the strength of the paper web. There is a tendency to use round mesh machines when casting paper, where the formation of the paper web is carried out on cylinders covered with mesh and located in a bath or without a bath, into which paper pulp is supplied. In a rotoformer machine, the headbox and the screen part are made in one compact unit, and dewatering is carried out using a suction chamber located inside a rotating shaft. The speed of such machines is up to 300 m/min. They can work with low concentrations, which is important when producing papers from artificial fibers.

In the production of long-fiber papers made from cotton, asbestos and synthetic materials, “dry spinning of the paper web is used, based on the principle of deposition on a mesh of fibers dispersed in an air flow. It is possible that such forming will be widely used for the production of technical and special types of paper.

Further increases in the efficiency of a paper-making machine are associated with changes in paper production technology, improvements in the design of the machine and individual components, and an increase in productivity due to speed and width. A sharp increase in the speed and width of the machine will be ensured by: flow distributors and closed head boxes, which allow the mass to be released onto the mesh at a speed corresponding to the increased speed of the mesh; register rollers of grooved and mesh type, hydroplanes, two- and three-chamber suction couch rolls that intensify dewatering; new types of presses, rubberized suction rolls and rolls fixed in the middle, rolls with grooved corrugation, presses with backing mesh, vacuum suction felt washers, rolls mounted on a calender open frame with hinged levers, fixed in the middle, floating, not requiring bombardment for deflection compensation; periphery, such as reels for winding rolls with a diameter of up to 2200-2500 .il with pneumatic roll clamping and automatic transmission it from the filling stations to the working supports, etc. In the drying part of the paper machine, provision is made for the use of higher steam pressure, new steam distribution circuits with steam circulation, siphon removal of condensate, fully closed hoods over the drying part, installation of drying nets instead of drying cloths, etc. Further. In addition to the widespread and relatively cheap drying through contact of the surface of the drying cylinders of the machine with the paper web, new types are being sought that would significantly reduce working area drying part, improve drying uniformity. New types of dielectric drying are promising. (due to high frequency current passed through the paper web): irradiation with infrared rays; blowing hot air; under vacuum.

-paper

As you know, trees consist of a special soft structural mass - wood. It burns well, so it is used as fuel, is easily processed, and is suitable as a material for construction and raw material for paper. Wood has very diverse properties: malleable in processing, ductile, and durable at the same time. A variety of products are made from wood, such as timber of various sections, boards, wood panels of various types, which are used in construction, interior and exterior decoration of residential and non-residential premises, for the production of cabinet, solid furniture, and other items. Wood different breeds trees have diverse, distinctive properties. For example, it has exceptional flexibility and is resistant to stretching, compression and twisting, and balsa wood, native to South America, produces very strong and at the same time light wood. With the help of international freight transport These tree varieties are widely used in production in Europe.
Paper, waste paper.

Paper production is based on raw materials made from wood - cellulose. Paper is used to make books, notebooks, food packaging, filters for technical needs, etc.

Cellulose is not the only initial raw material. In some areas requiring the use of paper, such as banknotes, special layers of wood are used, usually young, moisture-saturated, physiologically active subcortical - sapwood. The central trunk part of the tree's durable wood is called the pith.

Sawmills turn tree trunks into lumber. First, the bark is stripped from the trunk, and then it is sawed with mechanical saws into boards or timber, depending on the purpose of the lumber. An approximate diagram of the production process: stripping the bark from a tree trunk - grinding wood into chips - mixing wood chips with water and adding special chemicals - boiling until wood pulp (pulp) is formed - splitting the resulting pulp into fibers - bleaching - squeezing and drying the pulp - removing moisture and pressing into paper sheets - smoothing and rolling the resulting paper into a roll.

The paper used in printing is made from cellulose fibers of the cotton plant. This paper is very smooth, even, and has increased strength. What is interesting about the averaged data in developed countries In the world, per capita consumption is about 250 - 350 kg. paper per year. Approximately 50% of this paper waste is reused to make newspapers, toilet paper, and packaging paper products. The remainder is disposed of in specially designated areas or burned.

Paper making.

Nowadays, for the production of paper, mainly coniferous tree species are used: pine, fir, spruce. Cellulose contained in wood fibers gives strength to the resulting paper. Modern paper production is based on grinding wood and boiling the resulting mass with various chemical reagents (caustic soda) and, as a result of chemical processes, pure cellulose is obtained from wood. The resulting mass is squeezed out, cleaned, various impurities are removed by filtration, and then a thin layer is passed along a conveyor line through rows of hot rollers, due to which the paper is pressed and residual moisture is removed.

Paper production

As you already know, paper was invented in China. The Chinese made it from soaked plant fibers. Paper came to Europe between 1000 and 1100 years. It turned out that it can be made from wood, rags and even... from old paper - waste paper. It turned out that the paper could be used twice!
How is paper made these days?

Paper is produced in paper mills.
The main raw material for paper production is wood pulp. Cellulose is obtained from forest species: mainly from spruce, pine and pine, but eucalyptus, poplar, chestnut and other trees are also used.
At the factory, machines strip the bark from them and crush them into chips. Wood grinding for paper production
The most economical way to obtain wood pulp is mechanical: at a wood processing plant, timber is crushed into crumbs, which are mixed with water. Paper made from such cellulose is fragile and is most often used in the production of, for example, newspapers.

Higher quality paper is made from cellulose obtained from chemically. This wood pulp is used to make paper for books, brochures and fashion magazines, as well as durable wrapping materials.

In this case, the chips are sorted by size on special sieves and sent for cooking. The wood is boiled in special machines to which acid is added.

Cooking wood
Cleaned and boiled wood is filtered and washed to remove impurities.
Waste paper can be added to the processed paper pulp, but only after the ink has been removed. At this stage of production, the processed pulp, consisting of wood fibers and water, is called raw paper.
Then, a special processing machine changes the shape and structure of the paper fibers. To do this, additional substances are added to the paper raw material. For example, adhesives - their presence in writing paper repels moisture. Or resins - thanks to them, what is written on paper with water-based ink does not spread and is easily recognized by the human eye. Paper used for printing does not require the same sizing as writing paper, because printing inks are not water-based and do not bleed.
After this, the paper is dyed in a mixer, where dyes or pigments are added, for example, finely ground coating substances. Thus, kaolin additives make paper white and opaque.
Impregnation of cellulose with filler Adding dyes to cellulose

The paper pulp, turned into pulp, enters the paper making machine.
First, the slurry is poured onto the mesh of the paper machine. This mesh is stretched over two shafts and rotates all the time, carrying the paper pulp forward. At the mesh section, the formation of the paper web, called sheet forming, begins. This occurs by removing water from the fibrous material. As the paper pulp moves along the conveyor belt, some of the water contained in it flows out through the mesh holes, and the paper fibers begin to intertwine with each other, forming the so-called roll tape.
Mesh Making Machine

The raw paper strip passes through a series of rollers. Some rollers squeeze out the water, others, heated from the inside by steam, dry it, and others polish it.
Drying paper web

At the end of the wire section, the still wet paper web is moved to a pressing section, which is also called “wet pressing”. There, the paper web is mechanically dehydrated and further compacted.

Finally, the smooth white tape comes out of the machine and is wound into a huge roll.
Rolling paper
Then these rolls are sent to printing houses or cut into sheets.
So, moving from machine to machine, the wood turns into white and clean paper.

Manufacturing

At the wood processing plant, the cellulose is washed and filtered to remove impurities. Pulp intended for the production of white paper is additionally subject to bleaching. After this, it is turned into a sheet and dried, which will subsequently facilitate the paper production process. The sheets are baled at the pulp and paper mill, where a special machine called a pulp breaker rips the sheets open and mixes them with water. Often, pulp cooking and paper production from it take place continuously, without intermediate drying. Waste paper can be added to the processed paper pulp, but only after the ink has been removed. At this stage of production, the processed mass, consisting of wood fibers and water, is called paper raw material.

Then, on a special processing machine, the shape and structure of the paper fibers are changed in accordance with the requirements that the paper produced must meet. At the next stage, the paper pulp is mixed with other substances that give the final product the desired properties. Adhesives are substances whose presence in writing paper repels moisture. Resins are most often used for sizing paper. Thanks to them, what is written on paper with water-based ink does not spread and is easily recognized by the human eye. Paper used for printing does not require the same sizing as writing paper, since printing inks are not water-based and do not bleed. After this, the paper is dyed in a mixer, where dyes or components are added, for example, finely ground coating substances. Thus, kaolin additives make paper white and opaque. The most common method of making paper is the Fourdrinier method. From the mixer, the paper pulp is fed through a cylinder onto a conveyor, the belt of which is a mesh with cells: the width of this belt can reach 9 meters. The conveyor moves at speeds of up to 1000 m per mini.” The thickness and weight of paper coming off the conveyor depends on the speed at which raw materials arrive.

Paper making technology

It would seem that it would be difficult to produce an ordinary sheet of paper! However, this is a very labor-intensive and expensive process that requires a lot of time. Paper production includes a huge number of stages, only after passing which you can get finished products- clean White list. If you know at least a little about paper production, this will help you decide on the choice of high quality paper. Such paper will be highly smooth, will not damage printing equipment, and the image quality will be ideal.

Pulp and paper

Paper consists of cellulose fibers that are extracted from natural product– tree. High quality paper contains not only cellulose fibers, but also various other materials. Most often it is cotton or some other fabrics. Based on this, there is the concept of rag paper. The properties and characteristics of paper are influenced by many things. First of all, these are the tree species from which paper is made. Trees such as pine (and other conifers) make durable paper, but it has a rough surface. Coniferous trees has soft wood. Softwood trees are designed to make smooth paper; its disadvantage is its lack of strength. Quite often, in order for the paper to have a uniform composition, mixed types of wood are used in production. But papermaking is a process that is subject to frequent changes, and therefore paper can have different compositions and characteristics. In order for the quality of paper to remain at the proper level, it is necessary to constantly monitor and control the condition of the wood. This is a complex process that cannot be avoided in any production.

Paper making

Now we will describe some of the stages of paper making. At the initial stage of papermaking, the bark is removed from the tree and the wood is crushed. After which the crushed wood is exposed to chemicals, the output is liquid wood pulp. This process occurs under high pressure and temperature. Gradually, this mass changes color (becomes dark brown) and is called pulp. Then the pulp becomes white again. Pulp bleaching occurs in the following way - it passes through so-called mills, which not only bleach it, but also separate the fibers from each other. During this process, various chemical substances, which determine the quality of paper. Their color, properties, and how loose and tough the paper will be depend on them.

The chemicals that make up the paper pulp also affect its grade and reflectivity. After the pulp has acquired a white color, it can be used for production. In order to use the pulp for further work, it must contain at least 99.5% water. After this, the pulp passes through equipment - tubes of various diameters and lengths. Then, in order for the mass to be evenly distributed throughout the entire conveyor (a mesh with small cells), it is placed in a chamber with high pressure. Paper has two completely different sides, which have opposite properties and characteristics. Thus, the side of the paper that comes into contact with the conveyor is called the wire side, and the opposite side is called the felt side. Each side also has a different smoothness and deflection. Passing through the paper machine for about 6-10 m, the pulp loses moisture (at least 10%) and thereby turns into paper. The remaining moisture evaporates during the pumping and pressing process.

Paper sizing

The process of sizing paper consists of it leaving one part of the paper machine and entering another containing drums (the drums are heated warm air). In it, it passes through them and gradually loses a certain percentage of moisture. Paper sizing is needed to give the paper strength and also to secure its fibers. If the paper is poorly glued, it may not be suitable for xerography. This is because the top fibers can become detached and contaminate the equipment, causing it to break down and become unstable. The paper making machine contains two parts. And if in the first part of the machine the paper lost only a small percentage of moisture, then, passing through the second part, the amount of moisture in the paper is reduced to a minimum. The amount of moisture in paper must be strictly determined, since paper that has higher percentage moisture is subject to curling. Dry paper, on the contrary, breaks, and difficulties may arise with its post-printing processing (laying, feeding). The moisture content of the paper should not deviate from the specified amount even by 1%, since even such a small difference can affect its quality. Packing and cutting paper After the paper has gone through all the stages in the paper machine, it is wound onto large rollers. The weight of one such shaft can reach up to 15 tons. This procedure is necessary in order to give the paper required size, and also for it to cool down. The paper is not wound too tightly on such a shaft, so after that it is rewound onto smaller shafts, much tighter. After the paper has taken its shape, it is cut using special devices and it takes on a standard form (strips of a certain width). You can cut paper only with such special devices, as they provide a uniform cut that does not break or crumble. Unfortunately, some printing houses still use a guillotine cutter, which does not produce such high quality. After cutting, the paper comes into rolls, which are transferred to automatic device. It, in turn, cuts these strips into sheets and packs them into bundles (500 sheets each). Each pack is packed in wrapping material. Unlike other paper manufacturers, boxes with Xerox paper are packaged in moisture-resistant material, so the moisture in the boxes is maintained constant. This helps maintain paper quality over a long shelf life.

Packing in boxes and storing on pallets

After the paper is packed into bundles, boxes containing them are formed. Boxes are placed on wooden pallets, preferably if the pallets are covered with plastic. In this case, the impact is reduced environment, mainly moisture on the paper. The paper can now be delivered to users. From pulp to paper In order to know which paper is best to purchase, you need to navigate its production. Knowing exactly what environmental and manufacturing factors affect paper quality will help you choose the paper that is of the highest quality. Thus, you will prolong the operation of your equipment, and you will not have to constantly resort to the services of repair teams.

Stage 1. At the first stage, pre-processing of wood raw materials is carried out.

Spruce is sawn on slasher tables with circular saws into a measuring balance 1.2 m long, freed from bark (debarked) in debarking drums using a dry method (without supplying water to the drum). Part of the debarked pulp is crushed to produce process chips in chippers.

Stage 2. At the second stage, the production of semi-finished products occurs - wood pulp and thermomechanical mass.

In the wood pulp shop, wood pulp is obtained by mechanically abrading the measured balance in defibrators. Pulpwood is loaded into the defibrator shaft and pressed along its entire length against a rotating ceramic stone, as a result of which the wood is divided into fibers. Wood pulp undergoes sorting, cleaning, thickening and bleaching.

In the thermomechanical mass shop, thermomechanical mass is obtained from technological chips by two-stage grinding of steamed chips under pressure. It also undergoes sorting thickening and bleaching.

Stage 3. The third stage is paper production.

The resulting semi-finished products - thermomechanical pulp and wood pulp, as well as imported commercial bleached sulphate pulp, dissolved and ground, make up the composition of the paper pulp from which newsprint is produced.

The paper pulp, after preliminary sorting, cleaning, deaeration and fine sorting, is supplied to a paper-making machine, where the paper web is formed in the mesh part, dewatered under the pressure of press rolls, dried while passing through drying cylinders heated from the inside with steam, increasing the smoothness of the paper as it passes. between the calender rolls and winding the finished paper onto the reeling shaft. Then, on a slitting machine, the paper is cut into rolls of the required formats, packaged and stored. Paper is shipped by rail, road and water transport.

Paper is a material for writing, printing, drawing, packaging, hygiene needs, etc. Paper is usually made in the form of sheets or rolls. The raw material is cellulose, which in turn is obtained from plant material or recyclable materials (rags, waste paper).

The word “paper” itself supposedly comes from the Italian “bambagia”, or the Tatar “bumug” - cotton. Although everyone knows that the Chinese invented paper. Chinese chronicles attribute this invention to Cai Lun. He is supposedly the first to crush mulberry tree fiber, wood ash, hemp and rags, mixed with water and placed on a bamboo sieve. After this mass dried in the sun, strong sheets were obtained, which Tsai Lun leveled under a stone press.

However archaeological excavations(1957) “aged” the paper by at least 200-300 years, this is how the finds in one of the tombs of the Baoqia cave are dated. To be fair, let’s say that this cave is located in the north of China, so archaeological research has not yet challenged the priority of the Chinese in this area. Did paper exist before this? Yes, it was made from defective silk cocoons, which were not suitable for the production of high-quality famous Chinese silk.

One way or another, gradually, or rather very gradually, after several centuries, paper comes to other Asian countries, and later to the Arabs. Only in the Middle Ages did it replace animal parchment in Europe! And although the demand for it is growing, especially with the advent of book printing presses in the 15th and 16th centuries, the process of making paper remains just as primitive. The raw material is ground manually using wooden hammers and then scooped out using mesh molds.

Finally, in the mid-17th century, a grinding apparatus was invented, but the casting remained manual. The big disadvantage of this paper was that it left traces of the grid on it. Around 1770, this drawback was eliminated thanks to the introduction of a new paper form, thanks to the famous English manufacturer D. Whatman. In his honor, white high-grade paper for drawing and drawing is still called this way.

A little later, in 1806, the invention of carbon paper was patented, and in 1856 it was invented corrugated cardboard, and just a year later, in 1857, the technology for making paper from wood appeared. However, even earlier, in 1799, the first paper-making machine was invented in France. The casting process was mechanized thanks to a continuously moving casting mesh.

The British, the Fourdrinier brothers, acquired the patent from the author of the machine, N.L. Robert. They improved the mechanization of low tide and patented their machine in 1816. After just a few decades, it turned into a complex, continuously operating semi-automatic unit.

In the 20th century, paper production became the largest highly mechanized and high-tech industry in many countries. It is distinguished by its own production of raw materials, powerful thermal power plants and continuous flow production technology.

At first, paper was also used for hygienic purposes only in China. We first read about such an application in the notes of the Chinese official and scientist Yang Zhitui, dated 589. Industrial production The toilet paper industry began in the mid-19th century in New York City as prepackaged sheets soaked in aloe juice. Since 1884, toilet paper began to be produced in rolls.

Among special types paper - bibldruk (ultra-light offset paper, which is used for large dictionaries, bibles, etc.) and paper for the production of banknotes. It seems that the Chinese were also pioneers in this field; a Chinese cliché from the 12th century, which was used for such production, has survived to this day.

Today for making paper money They use special high-grade paper, the most important requirements for which are: resistance to tearing, fracture, and wear resistance. Of particular importance are watermarks and other methods of protecting banknotes from counterfeiting.

To produce paper, you need materials with sufficiently long fibers that, when mixed with water, produce a homogeneous, plastic mass. Today, as semi-finished products for paper production apply:

Wood pulp (mass);
- cellulose of annual plants (hemp, rice, straw, reed, etc.);
- semi-cellulose;
- waste paper;
- semi-rag rag (cotton, used for the best grades of paper).

To produce special types of paper, materials such as wool, asbestos, etc. can be used. Most of the cellulose fibers for paper production come from wood. By the location of the paper mill, you can immediately determine what the paper is made from and what its quality is.

Coniferous forests (pine, for example) provide soft wood, which is used to make slightly rough but durable paper. The harder wood of broad-leaved trees produces paper that is less durable but smoother. Often a mixture of wood fibers from soft and hardwood is used to make paper.

Making paper from wood pulp begins by removing the bark from the tree. Further production itself consists of the following processes:

1. grinding, mixing components of paper pulp, sizing, filling, coloring;
2. dilution with water, removal of contaminants;
3. casting, pressing and drying paper, primary finishing;
4. calendering (final finishing), cutting;
5. paper sorting and packaging.

To increase rigidity and strength, it is necessary to strengthen the bonds between the fibers; for this purpose, starch and animal glue are added. To protect against soaking - melamine and urea-formaldehyde resins. Mineral fillers such as kaolin, chalk, talc improve the printing properties of paper, its whiteness, smoothness and softness. Aniline dyes (sometimes mineral) are also used to increase whiteness and add color to paper.

For the production of some types of paper, such as absorbent, electrical insulating, sizing and fillers are not needed. Rice paper and paper made from hemp pulp are whiter than those made from wood pulp, and often do not require additional chemical bleaching.

Paper production is carried out at pulp and paper mills. These enterprises are located not far from bodies of water, since paper manufacturing technology involves the use of significant volumes of water. The main material used for paper production is various types of wood (mostly coniferous, because they consist of 40–50% cellulose) and waste paper. IN special cases cotton is used. Another type of raw material that has appeared relatively recently is synthetic fibers. Also, the basis for paper production can be rags, fibers of annual plants, wool, and asbestos.

For the production of paper, semi-finished products such as cellulose and wood pulp in different proportions are most often used.

Harvested wood undergoes special processing: chemical and mechanical.

Cellulose is obtained by boiling wood in a chemical solution. It is this that gives the material its whiteness and high strength. Cellulose in a semi-raw form can be immediately sent to the workshop for further processing, or it can be compressed, dried and sent in the form of gray sheets for sale to other enterprises. In its pure form, cellulose is used to produce high-quality, expensive grades of paper.

Mechanical processing and grinding of wood leads to the formation of wood pulp - particles with a diameter of two to three millimeters. This semi-finished product contains not only cellulose, but also lignin, a polymer that holds plant fibers together. It is because of this substance that printed products printed on newsprint turn yellowish-brown over time when exposed to light. Wood pulp in its pure form can only be used for the production of inexpensive grades of paper (newspaper, packaging).

Wood pulp after grinding wood

How paper is made

Production begins with the production of paper pulp, which is a mixture of water, cellulose and wood pulp (the ratio of cellulose and wood pulp determines the future characteristics of the product) with the addition of various substances for sizing, coloring, improving the properties of the material (glue, resin, starch, chalk , kaolin and others). The ratio of water to fiber is such that the paper pulp is a 2.5–3% suspension.

The pre-cleaned paper pulp enters the paper-making machine - a complex unit of enormous size (length - over 100 m, width - 15-18 m). In one minute, the semi-finished product manages to pass through all parts of the paper machine;NOTE_MOBILE_740#

Paper making machine

• Mesh part. Under pressure, this composition is continuously fed to the moving wire mesh of the paper machine. The paper manufacturing technology is such that the fibers are arranged and intertwined along the movement of the mesh, creating a machine direction that will subsequently play important role when using the finished product. As the mesh moves, the water gradually leaves and the paper web is formed.
• Press part. During the pressing process, the canvas passes between several pairs of press rollers, compacting and releasing most of the moisture.
• Drying part. In it, the base paper is dried by heated steam cylinders. But even after this, up to 8% moisture remains in the canvas.
• Calenders. The canvas, pre-cooled by cold drums, undergoes calendering - it is passed between heavy polished rollers - calenders to give it greater smoothness and strength. Calendered paper is wound into a roll and cut into smaller rolls or unrolled and cut into sheets.