The main stages of the production of chemical fibers. "Types of chemical fibers

22.11.2021 -

The 19th century was marked by important discoveries in science and technology. A sharp technical boom affected almost all areas of production, many processes were automated and moved to a qualitatively new level. The technical revolution did not bypass the textile industry either - in 1890, a fiber made using chemical reactions was first obtained in France. The history of chemical fibers began with this event.

Types, classification and properties of chemical fibers

According to the classification, all fibers are divided into two main groups: organic and inorganic. Organic fibers include artificial and synthetic fibers. The difference between them is that artificial ones are created from natural materials (polymers), but with the help of chemical reactions. Synthetic fibers use synthetic polymers as raw materials, while the processes for obtaining fabrics are not fundamentally different. Inorganic fibers include a group of mineral fibers that are obtained from inorganic raw materials.

As a raw material for artificial fibers, hydrated cellulose, cellulose acetate and protein polymers are used, for synthetic fibers - carbochain and heterochain polymers.

Due to the fact that chemical processes are used in the production of chemical fibers, the properties of the fibers, primarily mechanical, can be changed using different parameters of the production process.

The main distinguishing properties of chemical fibers, in comparison with natural ones, are:

high strength;
the ability to stretch;
tensile strength and long-term loads of different strengths;
resistance to light, moisture, bacteria;
crease resistance.

Some special types are resistant to high temperatures and aggressive environments.

GOST chemical threads

According to the All-Russian GOST, the classification of chemical fibers is quite complicated.

Artificial fibers and threads, according to GOST, are divided into:

artificial fibers;
artificial threads for cord fabric;
artificial threads for technical products;
technical threads for twine;
artificial textile threads.

Synthetic fibers and threads, in turn, consist of the following groups: synthetic fibers, synthetic threads for cord fabric, for technical products, film and textile synthetic threads.

Each group includes one or more subspecies. Each subspecies has its own code in the catalog.

Technology of obtaining, production of chemical fibers

The production of chemical fibers has great advantages over natural fibers:

firstly, their production does not depend on the season;
secondly, the production process itself, although quite complicated, is much less laborious;
thirdly, it is an opportunity to obtain a fiber with pre-set parameters.

From a technological point of view, these processes are complex and always consist of several stages. First, the raw material is obtained, then it is converted into a special spinning solution, then the fibers are formed and finished.

Various techniques are used to form fibers:

use of wet, dry or dry-wet mortar;
application of metal foil cutting;
drawing from a melt or dispersion;
drawing;
flattening;
gel molding.

Application of chemical fibers

Chemical fibers have a very wide application in many industries. Their main advantage is relatively low cost and long service life. Fabrics made from chemical fibers are actively used for sewing special clothes, in the automotive industry - for strengthening tires. In the technique of various kinds, non-woven materials made of synthetic or mineral fibers are more often used.

Textile chemical fibers

Gaseous products of oil and coal processing are used as raw materials for the production of textile fibers of chemical origin (in particular, for the production of synthetic fibers). Thus, fibers are synthesized that differ in composition, properties and combustion method.

Among the most popular:

polyester fibers (lavsan, krimplen);
polyamide fibers (nylon, nylon);
polyacrylonitrile fibers (nitron, acrylic);
elastane fiber (lycra, dorlastan).

Among the artificial fibers, the most common are viscose and acetate. Viscose fibers are obtained from cellulose - mainly spruce. Through chemical processes, this fiber can be given a visual resemblance to natural silk, wool or cotton. Acetate fiber is made from waste from cotton production, so they absorb moisture well.

Chemical fiber nonwovens

Nonwoven materials can be obtained from both natural and chemical fibers. Often non-woven materials are produced from recycled materials and waste from other industries.

The fibrous base, prepared by mechanical, aerodynamic, hydraulic, electrostatic or fiber-forming methods, is fastened.

The main stage in the production of nonwoven materials is the stage of bonding the fibrous base, obtained by one of the following methods:

Chemical or adhesive (adhesive)- the formed web is impregnated, coated or sprinkled with a binder component in the form of an aqueous solution, the application of which can be continuous or fragmented.
Thermal- this method uses the thermoplastic properties of some synthetic fibers. Sometimes the fibers that make up the nonwoven material are used, but in most cases, a small amount of fibers with a low melting point (bicomponent) is deliberately added to the nonwoven material at the spinning stage.

Chemical fiber industry facilities

Since the chemical production covers several industries, all chemical industry facilities are divided into 5 classes depending on the raw materials and application:

organic matter;
inorganic substances;
organic synthesis materials;
pure substances and chemicals;
pharmaceutical and medical group.

According to the type of purpose, chemical fiber industry facilities are divided into main, general factory and auxiliary.

Natural and chemical fibers…………………………………………...…….3

Fields of application of chemical fibers…………….………………………..5

Classification of chemical fibers………………………………………..…..7

Quality management of chemical fibers…………………….…………...…9

The technological process of obtaining chemical fibers……………...…..10

Production flexibility……………………………………………………………..14

List of literature used……………………………………………………………………………………………………15

Natural and chemical fibers

All types of fibers, depending on the origin, are divided into two groups - natural and chemical. Among natural fibers, organic (cotton, linen, hemp, wool, natural silk) and inorganic (asbestos) fibers are distinguished.

The development of the chemical fiber industry is directly dependent on the availability and accessibility of the main types of raw materials. Wood, oil, coal, natural gas and refinery gases, which are the feedstock for the production of chemical fibers, are available in our country in sufficient quantities.

Chemical fibers have long ceased to be only substitutes for silk and other natural fibers (cotton, wool). At present, they form a completely new class of fibers, which has independent significance. Beautiful, durable and generally accessible consumer goods, as well as high-quality technical products that are not inferior in quality to products made from natural fibers, and in many cases surpass them in a number of important indicators, can be made from chemical fibers.

In the textile and knitwear industry, chemical fibers are used both in pure form and in mixtures with other fibers. They are used to produce clothing, dress, lining, linen, decorative and upholstery fabrics; artificial furs, carpets, stockings, underwear, dresses, outerwear, knitwear and other products.

The rapid development of the production of chemical fibers is stimulated by a number of objective reasons:

a) the production of chemical fibers requires less capital investment per unit of output than the production of any type of natural fiber;

b) the labor costs required for the production of chemical fibers are significantly lower than in the production of any type of natural fibers;

c) chemical fibers have a variety of properties, which ensures high quality products. In addition, the use of chemical fibers allows you to expand the range of textile products. No less important is the fact that the properties of natural fibers can be changed only within very narrow limits, while the properties of chemical fibers, by varying the conditions of formation or subsequent processing, can be directionally changed in a very wide range.

Fields of application of chemical fibers

Depending on the purpose, chemical fibers are produced in the form of monofilaments, complex filaments, staple fibers and tow.

Monofilaments - single threads of great length, not dividing in the longitudinal direction and suitable for the direct manufacture of textile and technical products. Monofilament is most often used in the form of fishing line, as well as for the manufacture of fishing nets and flour sieves. Sometimes monofilaments are also used in various measuring instruments.

Complex threads - consist of two or more elementary threads, interconnected by twisting, gluing, and suitable for the direct manufacture of products. Complex threads, in turn, are divided into two groups: textile and technical. Textile threads are thin threads intended primarily for the manufacture of consumer goods. Technical threads include threads with a high linear density used for the manufacture of technical and cord products (car and aircraft tires, conveyor belts, drive belts).

Recently, complex threads of high tensile strength and minimal deformation under loading (high modulus) have been widely used for reinforcing plastics, and high-strength threads with special properties for the manufacture of road surfaces.

Staple fiber, consisting of filaments of various cut lengths, until recently was used only for the manufacture of yarn on cotton, wool and flax spinning machines. At present, fibers with a round cross-section are widely used for the manufacture of wall and floor carpets and the top layer of floors. Fibers with a length of 2 - 3 mm (fibrids) are used for the manufacture of synthetic paper.

A tow consisting of a large number of longitudinally folded filaments is used to make yarn on textile machines.

For products of a certain range (outer jersey, hosiery, etc.), textured threads are produced, which, by additional processing, are given increased bulk, crimp or stretch.

All currently produced chemical fibers can be divided into two groups in terms of production volume - large-tonnage and low-tonnage. Multi-tonnage fibers and threads are intended for the mass production of consumer goods and technical products. Such fibers are produced on a large scale based on a small number of initial polymers (HC, LC, PA, PET, PAN, PO).

Low-tonnage fibers, or, as they are also called, fibers for special purposes, are produced in small quantities due to their specific properties. They are used in engineering, medicine and a number of sectors of the national economy. These include heat- and heat-resistant, bactericidal, fire-resistant, chemisorption and other fibers. Depending on the nature of the initial fiber-forming polymer, chemical fibers are divided into artificial and synthetic.

Depending on the nature of the initial fiber-forming polymer, chemical fibers are divided into artificial and synthetic.

Classification of chemical fibers

Artificial fibers are produced on the basis of natural polymers and are divided into hydrated cellulose, acetate and protein. The most multi-tonnage are hydrated cellulose fibers obtained by the viscose or copper-ammonia method.

Acetate fibers are produced on the basis of acetic acid esters (acetates) of cellulose with different contents of acetate groups (VAC and TAC fibers).

Fibers based on proteins of plant and animal origin are produced in very limited quantities due to their low quality and the use of food raw materials for their production.

Synthetic fibers are produced from polymers synthesized in industry from simple substances (caprolactam, acrylonitrile, propylene, etc.). Depending on the chemical structure of the macromolecules of the initial fiber-forming polymer, they are divided into two groups: carbochain and heterochain.

Carbochain fibers include fibers obtained on the basis of a polymer, the main macromolecular chain of which is built only from carbon atoms connected to each other. Polyacrylonitrile and polyolefin fibers have received the greatest application from this group of fibers. To a lesser extent, but still in relatively large quantities, fibers based on polyvinyl chloride and polyvinyl alcohol are produced. Fluorine-containing fibers are produced in limited quantities.

Heterochain fibers include fibers obtained from polymers, the main macromolecular chains of which, in addition to carbon nitrogen, contain atoms of oxygen, nitrogen, or other elements. Fibers of this group - polyethylene terephthalate and polyamide - are the most multi-tonnage of all chemical fibers. Polyurethane fibers are produced in a relatively small volume.

Of particular note is the group of high-strength high-modulus fibers for technical purposes - carbon, obtained from graphitized or charred polymers, glass, metal or fibers obtained from metal nitrides or carbides. These fibers are mainly used for the manufacture of reinforced plastics and other structural materials.

Quality management of chemical fibers

Chemical fibers often have high tensile strength [up to 1200 MN/m2 (120 kgf/mm2)], which means rupture elongation, good dimensional stability, crease resistance, high resistance to repeated and alternating loads, resistance to light, moisture, mold, bacteria, chemo- and heat resistance. Physical-mechanical and physico-chemical properties of chemical fibers can be changed in the processes of spinning, drawing, finishing and heat treatment, as well as by modifying both the feedstock (polymer) and the fiber itself. This makes it possible to create, even from a single initial fiber-forming polymer, chemical fibers with a variety of textile and other properties. Man-made fibers can be used in blends with natural fibers in the manufacture of new ranges of textiles, significantly improving the quality and appearance of the latter.

Technological process for obtaining chemical fibers

The technological process for the production of chemical fibers usually includes three stages. The only exception is the production of polyamide, polyethylene terephthalate and some other fibers, where the technological process begins with the synthesis of a fiber-forming polymer.

The first stage of the process is to obtain a spinning solution or melt. At this stage, the original polymer is transferred to a viscous state by dissolution or melting. In some cases (obtaining PVA fibers), the transfer of the polymer into a viscous state also occurs as a result of plasticization. The resulting spinning solution or melt is subjected to mixing and purification (filtration, deairing). At this stage, in order to impart certain properties to the fibers, various additives (thermal stabilizers, dyes, matting agents, etc.) are sometimes introduced into the spinning solution or melt.

Topic: 1.Technology for the production of chemical fibers

2.Properties of chemical fibers

Target:

study the classification of textile fibers ; to acquaint students with the process of obtaining chemical fibers and their properties; to teach students how to use the properties of fibers in the manufacture of products from them and care for them;
cultivate aesthetic taste, attentiveness;
develop logical thinking.

Learning new material.

Verbal and illustrative story.

For many centuries, people used in the production of those fibers that nature gave them - fibers of wild plants, animal hair, flax and hemp fibers. With the development of agriculture, people began to grow cotton, which gives a very good and durable fiber.

But natural raw materials have their drawbacks. Natural fibers, for example, are too short, not strong enough, and require complicated processing. And people began to look for raw materials from which it would be possible to obtain fabric in a cheap way, warm like wool, light and beautiful, like silk, cheap and practical, like cotton.

The advances in modern chemistry have made it possible to create such a chemical fiber from natural materials, mainly cellulose obtained from wood and straw. Such a fiber is called artificial, and fiber, and fiber made from synthetic polymers, is called synthetic.

Chemical fibers are fibers created artificially through physical and chemical processes.

Not a single specialist is now able to enumerate all the vast array of chemical fibers that are used for the production of fabrics. And in laboratories, more and more of their types are synthesized.

The practical prerequisites for the creation of artificial silk were created by the inventions of the 19th century.

Cotton and bast fibers contain cellulose. Several methods were developed to obtain a solution of cellulose, forcing it through a narrow hole (die) and removing the solvent, after which threads similar to silk were obtained. Acetic acid, alkaline copper hydroxide solution, sodium hydroxide, and carbon disulfide were used as solvents. The resulting threads are respectively called acetate, copper ammonium and viscose.

The large group of filaments emerging from the spinnerets is drawn, twisted together and wound as a complex filament onto a cartridge.

To obtain a staple fiber, the complex thread after finishing operations is cut into fibers of a given length.

Synthetic fibers are made from polymeric materials. Fiber-forming polymers are synthesized from such widely used petroleum products as benzene, phenol, ammonia, etc. By changing the composition of the feedstock and the methods of its processing, synthetic fibers can be given unique properties that natural fibers do not have. Synthetic fibers are obtained mainly from the melt, for example, fibers from polyester, polyamide, pressed through spinnerets.

Depending on the type of chemical raw material and the conditions of its formation, it is possible to produce fibers with a variety of predetermined properties. For example, the stronger you pull the jet at the moment it exits the spinneret, the stronger the fiber is. Sometimes chemical fibers are even stronger than steel wire of the same thickness.

Synthetic fibers are also available in the form of monofilaments, multifilament and textured yarns, and staple fibres.

Fibers of the same type have different trade names in different countries. So, polyamide fiber in Russia is called capron, in the USA - nylon, in Germany - perlon.

Consider the properties of some artificial and synthetic fibers. (During the explanation, students look at fiber samples from the Textile Fibers visual aid and fabric samples.

Viscose fiber.

The raw materials for the production of viscose fiber are wood pulp (spruce chips, sawdust) and chemicals. Viscose fiber is very similar to natural silk fiber. The length and thickness (thinness) of the fibers can be any, the color depends on the dyes added to the solution.

Viscose fibers are soft, smooth, straight, with a strong sheen, less durable than natural silk fibers, have low elasticity, so fabrics made from these fibers are very wrinkled. Viscose fiber absorbs moisture well and dries quickly. Viscose fiber burns like cotton with a yellow, fast-running flame. After combustion, gray ash and the smell of burnt paper remain.

Acetate fibre.

Acetate fiber is obtained by combining waste from cotton with chemicals. Acetate fibers also have an arbitrary length. They are straight, thin, soft, durable, resistant to wear, resilient, so the fabrics from them hardly wrinkle, have a sharp sheen or no sheen at all. Acetate fibers do not absorb moisture well. The color of the fibers depends on the dyes added to the solution.

The acetate fiber burns slowly, with a yellow flame, a melted ball forms at the end, and a special sour smell is felt.

The properties of artificial silk fabrics depend on the properties of the fiber. These fabrics are smooth, with a sharp sheen or matte, heavier, thicker, stiffer than natural silk fabrics, have low shrinkage and heat resistance. These fabrics are durable, but when wet, their strength decreases, they drape well, they do not pass air well and absorb moisture. Washes well in soapy water. They give a slight shrinkage, have a large cut through when sewing products, and the threads move apart in the seams when worn. It is necessary to iron fabrics made of artificial silk very carefully, especially from acetate silk - the fabric turns yellow from strong heating.

Polyester fibers (lavsan, krimplen, etc.)

These fibers have a smooth, matte surface. They are durable, resistant to wear and tear. In a flame, they first melt, then slowly burn with a yellowish flame, releasing black soot. After cooling, a solid black ball forms.

A significant disadvantage of polyester fibers is low hygienic properties.

Polyamide fibers (kapron, nylon, dederon).

These fibers have a smooth shiny surface, are well wetted by water, but dry quickly. Polyamide fibers are sensitive to heat, already at a temperature of 65 degrees it loses strength, so ironing a product made from these fibers must be done carefully.

Polyamide fibers are strong and resistant to wear.

Hygienic properties are low.

The fiber burns with a weak bluish-yellow flame with a white haze. When cooled, a solid dark ball forms at the end.

Polyacrylonitrile fibers (nitron, acrylic, pearl, etc.).

These fibers are fluffy, matte, and look like wool, which is why they are often called "artificial wool." The strength and wear resistance of polyacrylonitrile fibers are lower than those of polyamide and polyester.

The hygienic properties of the fiber are also low.

The fiber burns in flashes, releasing large amounts of soot. After cooling, an influx forms, which can be crushed with your fingers.

Elastane fiber.

Lycra, dorlastan belong to elastane fiber. These fibers are most often used in a mixture with other fibers. Elastane fibers are very elastic, able to increase their length when stretched by 7 times, and then shrink to their original state.

Fabrics made from synthetic fibers are smooth, shiny, high strength. After washing, ironing is often not required.

Disadvantages of fabrics: low hygienic properties, slip, fraying, thread extension.

Wherever we are: at home, at school or on the street - our clothes absorb pollution both from the environment and directly from the body. A person through the pores of the skin releases a significant amount of sweat and other substances, traces of which we can see, for example, on the collar and cuffs of his clothes.

How to take care of our dresses, suits and jackets, first of all, depends on the material from which they are sewn. Or rather, from the raw material composition of the fabric.

Viscose products can be washed by hand or in a washing machine at a gentle cycle and low temperature (30-40 degrees). For washing use detergents for delicate fabrics. Things made of viscose should not be wrung out, twisted and dried in a centrifuge. After washing, the product, without squeezing, is hung up or laid out on a clean sheet or towel, rolled up with a tube along with the underlying fabric and gently wrung out. Stroke the viscose with a warm iron (the position of the thermostat is “silk”) when wet or through a damp iron. In this case, the product must not be overdried. Viscose garments can be dry cleaned.

Acetate products are washed by hand or in a washing machine at a temperature of 30 degrees and gentle mode. Hang to dry. Acetate dries quickly and does not require ironing. If necessary, the products are ironed from the wrong side through a dry iron with a weak heating of the iron. Dryers are not recommended.

Triacetate can be washed in a washing machine at a temperature of 70 degrees and ironed with a hot iron (thermostat position - "silk - wool").

Products made of polyester fibers are washed in a washing machine at a temperature of 40-60 degrees. For washing products made of white fabrics, universal detergents are used, for colored ones - detergents for thin or colored fabrics.

Polyester can be spun in the washing machine on gentle cycle and air dried. Do not use the drying program, as over-dried polyester is poorly ironed. Products from this fabric are ironed with a moderately heated iron (the position of the thermostat is “silk”) and through a damp iron. Things made of polyester tolerate dry cleaning well.

Polyamide products are washed and dried in the same way as polyester products, but it must be borne in mind that the water temperature during washing should not exceed 40 degrees. Iron products made of polyamide fibers at a minimum temperature without moisture.

Acrylic products are washed at a water temperature not exceeding 30 degrees. Automatic drying is not allowed.

Products made from fabrics containing elastane are washed

Student's report "It's interesting!" (Appendix No. 1)

2. Sketching the scheme "Chemical fibers" (Appendix No. 2).

3. Work with the textbook

Students write down in a workbook the main stages of the production process of chemical fibers (paragraph 12, pp. 47-48.) (Appendix 3)

Application No. 1

Report "It's interesting!"

An important step in the scientific and technological revolution of the 20th century was the discovery by the American company DuPont of a new class of synthetic fibers based on aromatic polyamides, abbreviated as aramids. Serial production of a new high-strength Kevlar fiber was launched by the company in 1972. Later, aramid fibers of two varieties began to be produced in other countries.

The complexity of the process of obtaining aramid fibers and, as a result, the high cost, have so far limited the growth of their production, but, of course, these are fibers with a great future. To see this, just look at their unique properties. Aramid fibers of one group (nomex, conex, phenylone) are used where resistance to flame and thermal effects is required, the second group (kevlar, terlon) has high mechanical strength combined with low weight. Nomex type fibers smolder in an open flame with a temperature of more than 400 degrees Celsius and quickly fade out of the flame. Their low thermal conductivity provides reliable protection against the effects of powerful heat fluxes. Protective clothing made of aramid fibers performs its functions even in an environment enriched with oxygen.

The strength of another group of aramid fibers (Kevlar) is 5 times higher than the strength of steel, moreover, they have no corrosion. Aramids are practically not affected by long-term temperature effects from -40 degrees to +130 degrees Celsius, they retain strength during short-term exposure temperatures from -196 to +500 degrees Celsius. Aramid-based composite materials are 22 percent lighter and 46 percent stronger than fiberglass-based materials. Aramids are also used for the manufacture of fabrics that protect against mechanical stress. The protective properties of bulletproof fabric made of Kevlar are 2 times higher than fabrics of similar purpose made of nylon, and vests made of such fabric weigh almost 2 times less than nylon bulletproof vests.

Among the new fibers that have already appeared, one can also note the so-called fibers - chameleons, i.e. fibers, some of whose properties change in accordance with changes in the environment. For example, hollow fibers have been developed into which a liquid containing colored magnets is poured. Using a magnetic pointer, you can change the pattern of a fabric made from such fibers.

Thermosetting fibers change their volume when the temperature changes, which causes a change in the heat transfer of the fabric. New artificial cotton-like fibers have been created, which practically do not differ from cotton fibers in terms of consumer properties.

Inorganic chemical fibers include silicate and metal fibers, and the first group includes glass, quartz, basalt, ceramic and some other types of fibers.

The secret of making glass fibers was discovered by the ancient Egyptians around 2000 BC, later lost and rediscovered by the Venetians in the 16th century. The technology for producing glass fibers was first described by Réaumur in 1734.

Around 1850, the Frenchman de Brunfau succeeded in creating a spinneret suitable for the production of glass threads with a diameter of 6-10 micrometers.

Glass fiber does not burn, is resistant to corrosion and biological influences, has high tensile strength, excellent optical, electrical, heat and sound insulation properties. For example, products made of glass staple fiber are 3.5 times more thermally insulating than asbestos. A layer of fiberglass mat 5 centimeters thick corresponds in thermal resistance to a brick wall 1 meter thick.

Silicone fibers have very interesting properties, products from which can be used at a temperature of 1000 degrees C.

High mechanical strength and good resistance to chemicals are ceramic fibers, the main form of which consists of a mixture of silicon oxide and aluminum oxide. Ceramic fibers can be used at temperatures around 1250 degrees C. They are also characterized by extremely high chemical resistance. Radiation resistance allows them to be used in astronautics.

By heat treatment (900 - 3000 degrees Celsius) of organic fibers, such as polyacrylonitrile, carbon fibers are obtained that have very high strength. The upper temperature limit for these fibers is higher than that for ceramic fibers. Carbon fibers are obtained in a continuous way, however, due to their high cost, their use has so far been limited to only a few special areas.

Application №2

Classification of chemical fibers

Application №3

Manufacturing process of chemical fibers

1. Obtaining a spinning solution. All chemical fibers, except for mineral ones, are produced from viscous solutions or melts, which are called spinning. For example, artificial fibers are obtained from cellulose mass dissolved in alkali, and synthetic fibers are obtained by adding chemical reactions of various substances.

2. Fiber forming. A viscous spinning solution is passed through spinnerets - caps with tiny holes. The number of holes in the die ranges from 24 to 36 thousand. Jets of the solution, flowing out of the spinnerets, harden, forming solid thin threads. Next, the threads from one spinneret are combined into one common thread on spinning machines, pulled out and wound on a bobbin.

3.Fiber finishing. The resulting threads are washed, dried, twisted, heat treated (to fix the twist). Some fibers are bleached, dyed, and treated with a soap solution for softness.

Fibers are bodies whose length is many times greater than their very small cross-sectional dimensions, usually measured in microns. Fibrous materials, i.e. substances consisting of fibers are widely used. These are various textile products, fur, leather, paper, etc. Almost until the beginning of the 20th century, only natural fibrous materials were used for the manufacture of fiber and fabrics based on it: cotton, linen, natural silk, etc.

For the first time, the production of artificial fiber was carried out by forcing cellulose nitrate ether in an alcohol-acetone mixture through narrow holes. In n.v. more than 500 different types of chemical fibers are already known, of which more than 40 have been mastered and are being produced by industry. According to their origin, all fibers can be divided into natural and chemical. Chemical, in turn, are divided into artificial, made from IUDs that are in nature in finished form (cellulose, casein) and synthetic fibers obtained from high polymers, pre-synthesized from monomers.

If the properties of natural fibers vary within narrow limits, then chemical fibers may have a set of predetermined properties depending on their future purpose. Consumer goods are produced from chemical fibers: fabrics, knitwear, clothes, shoes, etc. There are many similarities in the production of various types of man-made fibers, both from natural polymers and from resins, although each method has its own characteristics.

Schematic diagrams of the production of chemical fibers, regardless of the feedstock is divided into four stages.

1. Obtaining the starting material (semi-finished product). In the event that the raw materials are natural IUDs, they must first be cleaned of impurities. For synthetic fibers, this is the synthesis of polymers - the production of resin. With all the variety of initial polymeric materials, the following general requirements are imposed on them, which ensure the possibility of forming a fiber and its sufficient strength:

– linear structure of molecules, which allows dissolving or melting the starting material for spinning the fiber and orienting the molecules in the fiber;

- limited molecular weight, since with a small molecule, the strength of the fiber is not achieved, and if it is too large, difficulties arise in the formation of the fiber due to the low mobility of the molecules;

- the polymer must be pure, as impurities reduce the strength of the fiber.

2. Preparation of the spinning mass. Not all natural and synthetic materials can serve as the basis for fiber production. Obtaining viscous concentrated solutions - high polymers in available solvents or transferring the resin to a molten state is a prerequisite for the implementation of the spinning process. Only in a solution or in a molten state can conditions be created that make it possible to reduce the interaction energy of macromolecules and, after overcoming intermolecular bonds, to orient the molecules along the axis of the future fiber.

3. Fiber spinning is the most critical operation and lies in the fact that the spinning mass is fed into the spinneret (filament former), which has a large number of tiny holes in the bottom, depending on the spinning method. The bundles of fine fibers formed from the streams are continuously withdrawn through a series of guide devices to the receiving device and then pulled out by winding devices: a reel, a roller, a centrifuge. During spinning, linear macromolecules are oriented along the fiber axis. By varying the spinning and drawing conditions, different fiber properties can be obtained.

4. Finishing consists in giving the fiber various properties necessary for further processing. To do this, the fibers are cleaned by thorough washing from any impurities. In addition, the fiber is bleached, in some cases dyed, and treated with a soapy or grease-containing solution to be more slippery, which improves its ability to be processed in textile factories.

The viscose method for the production of artificial fiber from cellulose is the most widely used method. The production of viscose fibers in the form of silk, cord and staple is approximately 76% of all chemical fibers.

To prepare a spinning solution, cellulose with a moisture content of 5-6% in the form of sheets measuring 600 * 800 mm is treated with 18-20% sodium hydroxide solution (mercerization process). At the same time, cellulose, absorbing a solution of caustic soda, swells strongly. Most of the hemicellulose is washed out of it, intermolecular bonds are partially destroyed and as a result a new chemical compound is formed - alkaline cellulose.

[C 6 H 7 O 2 (OH) 3] n + nNaOH ↔ [C 6 H 7 O 2 (OH) 2 OH * NaOH] n

The reaction between cellulose and concentrated sodium hydroxide solution is reversible. Depending on the equipment used and the form of cellulose, the process is carried out at 20-50 0 C for 10-60 minutes. Then alkaline cellulose is squeezed out of excess sodium hydroxide, which is sent to regeneration, where it is filtered, strengthened, settled, and then returned to mercerization. Next, alkaline cellulose is crushed and kept under certain conditions (20-22 0 C). In this process, called pre-maturing, as a result of oxidation in an alkaline environment with atmospheric oxygen, the degree of polymerization of cellulose is reduced, which makes it possible to regulate the viscosity of the spinning solution subsequently obtained over a wide range. After that, the destructed alkaline cellulose is treated with carbon disulfide (cellulose xanthogenation). As a result of the reaction, orange-yellow cellulose xanthate is obtained, which, unlike the original cellulose, dissolves well in a 4-7% sodium hydroxide solution. The resulting viscous solution is called viscose. The composition and properties of the resulting cellulose xanthate largely depend on the duration and temperature of the process, as well as the amount of carbon disulfide introduced. All of the above operations are carried out sequentially in 4-5 separate devices or are carried out until the final dissolution in one device.

The availability and low cost of raw materials contribute to the widespread production of viscose fiber. Viscose fiber is resistant to organic solvents, withstands prolonged exposure to temperature. Among the shortcomings, it should be noted the weak resistance of the fiber to alkalis and a significant loss of strength in the wet state.

From viscose, in addition to silk and staples, cellophane, cord, astrakhan fur, artificial hair and bottle caps are obtained.

When cellulose reacts with acetic anhydride in the presence of acetic acid and sulfuric or perchloric acid is used as a catalyst, cellulose acetate ester is formed, and acetate fiber is formed from it. Polyamide fiber - nylon is obtained from nylon resin, the feedstock for which is caprolactam. The latter is produced as a white powder from phenol, benzene or cyclohexane.

- developed industry. Its products are in great demand, as they are actively used in various fields. Depending on the material used in the production, they acquire different properties and characteristics.

Classification and properties of chemical fibers

Products in this industry are divided into three main groups:

Artificial - organic high-molecular compounds obtained by influencing natural substances and extracting polymers from them act as raw materials.

Synthetic - used for the manufacture of low molecular weight compounds, from which organic polymers are extracted by synthesis.

Mineral - a group that differs significantly from the previous ones, as it is made from inorganic compounds and has special characteristics and properties.

Manufacture of chemical fibers has a number of advantages over natural ones. It does not depend on the season, weather and is less labor intensive. In addition, such threads are manufactured with predetermined physical and mechanical characteristics.

Chemical fibers have excellent resistance to tearing, bacteria and mold, dimensional stability, crease resistance, resistance to adverse effects (light, moisture, etc.), heat, and repeated loads. Their physico-mechanical and chemical properties can be changed by modifying the polymer used or the finished product. This makes it possible to produce fibers with different characteristics from the same raw material. In addition, chemical fibers of different structures can be mixed to create new models and expand the range of products.

Manufacturing specifics

Manufacturing process of chemical fibers quite complex and consists of several stages: obtaining the source material, converting it into a special spinning solution, forming fibers through spinnerets, and finishing them. Thread forming is a step that is of central importance for determining the characteristics of the product. It can be done in several ways:

using a wet or dry solution;

using a dry-wet solution;

sharp metal foil;

from the melt;

drawing;

flattening;

from dispersion;

gel molding.

In the production of chemical fibers, filters are used that purify the spinning melt or solution from mechanical impurities. They are made of palladium, platinum, gold or their alloys.

Lighting of chemical fibers and equipment for their manufacture at the exhibition "Chemistry"

For specialists and companies interested in studying the specifics production of chemical fibers, expanding the range of producers and presenting products of their enterprises, the Chemistry exhibition will be the best place. This is an event organized by the industry with the aim of highlighting its achievements in various fields, establishing contacts between companies, specialists, regions and countries. It covers all industries and provides enterprises with the opportunity to organize their exhibition activities and place a stand on the site of the Moscow Expocentre complex.

This center is widely known outside of Russia, and many companies take part in international events held in its pavilions. This ensures establishing contacts with foreign partners and attracting new sponsors to the industry. Investments are of great importance for the chemical industry, as it needs serious injections, including foreign ones. The sphere of production of chemical fibers, like many other industries, is interested in attracting investments that would contribute to its development and modernization. For exhibitors, in turn, this is an excellent opportunity to present their enterprises in the most favorable light and increase their attractiveness.

The exhibition "Chemistry" is interested in creating the most comfortable conditions for participants, as well as attracting the maximum number of visitors. Therefore, its organizers chose the Expocentre complex as the venue for the event.