Natural fabrics: the beauty and energy of nature. Cotton (cotton, cotton) fabric

How are fabrics made?

Weaving is one of the very first crafts mastered by primitive people. The method of producing fabric on a handloom was invented by an unknown ancient man who lived in the late Neolithic era. Centuries passed, the shape of the machine changed, new types of yarn appeared, industrial production took the place of manual production of fabric, but to this day the principle of obtaining a woven fabric from individual fibers remains practically unchanged.

How fabrics are made today

Raw materials for the production of fabrics

Initially, the wool of various animals, as well as hemp and linen fibers were used to make fabrics. Then, in the Middle Ages, silk and cotton were brought to Europe from Asia. Their appearance allowed to significantly expand the range of fabrics produced. In the twentieth century, scientists - chemists created artificial and synthetic fibers, which immediately began to be widely used in weaving.

All these types of fibers are used to make fabrics in our time. However, individual fibers by themselves are not suitable for the production of woven fabric, because natural fibers are too short and not strong enough, and chemical fibers, although long, are very thin. In order to make fabric from fibers, they must first be made into threads.

Spinning

The process of turning individual fibers into a single thread takes place in the spinning mill. Spinning of chemical and natural fibers has a number of significant differences.

Chemical fibers are obtained by forcing a synthetic mass through the thinnest holes - spinnerets, so they already have a given thickness and a very long length. The spinning of chemical fibers consists only in twisting several monofilaments together to obtain a single thread of the required thickness.

Natural fibers undergo more complex processing before turning into a thread.

1. First, compressed bales, in the form of which the fibers enter the factory, are sent to a loosening machine, which divides the dense mass into small pieces.
2. Then they are placed in a scutching drum, where further loosening and cleaning of the fibers from all kinds of rubbish takes place.
3. After that, in the carding machine, the fibers are finally separated, straightened and arranged in one direction in the form of a wide long ribbon.
4. Then this tape is pulled out and compacted, a roving is formed from it - not yet a thread, but not a fiber either.
5. The roving is wound on special bobbins, which are transferred to the spinning machine. There, the roving is finally stretched and tightly twisted - a finished thread suitable for fabric production is obtained.

How fabric is made

The fabric is made in a weaving factory. The weaving process itself consists in weaving together in a special order two perpendicularly arranged groups of threads.

This is done on a loom - the warp threads (those that run along a piece of fabric) are tucked into loops attached to the shafts of the loom. In a simple loom, there are only two of them, and the threads are threaded through them through one - the first into the loop of the first shaft, the next into the loop of the second shaft, after it again into the loop of the first, etc., until all the threads are threaded along the width of the machine.

The shafts can go down and up, when this happens, half of the warp threads also goes up, and the other half goes down - a gap is formed between them, into which a shuttle with a weft thread is tucked into it from one edge of the loom to the other. During the second cycle of work, the shafts change their location, and the shuttle is thrown back through the newly formed thread gap. After that, the whole process is repeated many times.

Thus, a fabric of the simplest, plain weave is obtained. By changing the number of shafts and the order in which the warp threads are threaded into them, more complex types of weaving can be obtained.

In addition to fabrics themselves, the industry also produces knitted fabrics and fabrics from non-woven materials, which differ from fabrics in the principle of connecting threads to each other. The structure of knitwear is created by loops of threads, and in non-woven materials, the fibers are connected mechanically or by adhesive.

Basic spinning processes

FABRIC TECHNOLOGY

First, from the feedstock - fibers or filaments - textile threads are produced: yarn or complex threads. Yarn is obtained by spinning fibers. Complex threads are twisted from several elementary threads.

Then, in the process of weaving, a fabric is produced from the resulting yarns or complex threads. At the same time, a harsh fabric is obtained, which is subjected to finishing, giving it a beautiful presentation.

The fibrous mass of natural fibers after collection and primary processing enters the spinning mill. Here, from fibers of limited length, a continuous strong thread is produced - yarn. This process is called spinning. Along with natural fibers, the spinning mills also process staple man-made fibers.

The raw materials for spinning are textile fibers: cotton, linen, wool, silk-weaving and sericulture waste, and various chemical fibers.

The spinning process can be divided into three stages:

Preparation of the fibrous mass and the formation of a tape from it;

Ribbon preparation for spinning and spinning;

Spinning.

The stage of preparation of the fibrous mass and the formation of a tape from it includes the processes of loosening, mixing, scutching, and carding.

When loosening, the densely compressed mass of fibers is divided into small pieces for better mixing and cleaning of the fibrous mass from weeds. Loosening is performed on feeders-rippers.

Individual batches of cotton, wool, and other fibers vary in length, thickness, moisture, and other properties. The loosened fibers from different batches are mixed together in order to obtain large batches of raw materials that are uniform in properties. Therefore, several batches of fibers are usually mixed. Fibers of different nature are also mixed to obtain yarns with specific properties. The main mixing takes place on the mixing grate. After mixing, the fibrous mass goes to the scutching.

Scutching provides further loosening and intensive cleaning of the mass of fibers from weeds. The loosened and cleaned fibers are converted into a canvas, which is wound into a roll. The process is carried out on scutching machines.

In order to separate small shreds and bundles of fibrous mass into individual fibers, the canvas is carded. Small tenacious impurities remaining after the processes of loosening and scutching are removed. When carded, a thin layer of combed fibers is used to form a fly or roving. Carding is carried out on carding machines, in which the fibrous web passes between the surfaces of carding tapes covered with thin sharp metal needles. A thin combed layer of fibers - a fleece-batt - when leaving the carding machine is passed through a funnel and is converted into a tape of non-uniform thickness, which is a bundle of fibers oriented in the longitudinal direction.

To obtain a roving, the fleece is not formed into a tape, but is divided into narrow ribbons, which, after compaction, are converted into a roving.

The second stage of the spinning process consists in preparing the sliver for spinning and spinning.

The preparation of the sliver for spinning consists of straightening and stretching the sliver. First, 6-8 tapes are put together, aligning them in thickness. To obtain a mixed yarn, tapes of different fibrous composition are connected. The folded tapes are evenly stretched, while the tape is thinned, the fibers are straightened and oriented.

The tapes are aligned and stretched on draw frames, which are equipped with several pairs of rollers rotating at increasing speed. Passing between the rollers, the tape gradually thins and the fibers in the tape are oriented in the direction of motion. Processing can be carried out sequentially on several machines to obtain progressively thinner strips. High-draw draw frames are widely used, replacing several draw frames.

Spinning is the gradual drawing of the tape into the roving. It is carried out on roving machines, where the tapes are finally drawn into a roving of the required thickness, slightly twisted to strengthen it, and also wound on a package of a given shape and size.

The third stage is spinning, during which the final thinning of the roving and its twisting occur, i.e., the transformation of the roving into yarn, as well as the winding of the yarn onto a package of a given shape and size. Spinning is performed on spinning machines.

Raw materials supplied to the spinning industry have different qualities: length, thickness, crimp of the fibers. From thin, long-staple raw materials, thin, smooth, dense yarn is obtained, and from shorter and thicker fibers - thick, fluffy and loose. The yarn production steps presented above remain the same for both thin and thick yarns. However, when spinning thin long or thick short fibers, each of the listed production steps has differences in technological processes and equipment. There are differences in processes and equipment in the production of yarn of different fiber composition.

The set of processes and machines by which the fibrous mass is processed into yarn is called the spinning system. Known spinning systems differ from each other mainly in the way in which two main processes are carried out: carding the pulp and thinning the product (Fig. 10).

Carded spinning system- the most common. Here the fibers are carded on carding machines. The thin layer of fibers removed from these machines is formed into a tape. Then the tape is successively thinned into roving and yarn by drawing in the drafting devices of subsequent machines. According to this system, yarn with a linear density of 15-84 tex is obtained from medium-staple cotton, as well as from chemical and short linen fibers.

Yarn spun according to this system from fibers dyed in the same or different colors (with the exception of linen) is called melange.

The carded yarn is fairly uniform, with medium cleanliness but not enough smoothness.

Carded yarn is used in the production of fabrics, knitted fabrics, stitched non-woven materials, some types of ribbons, ribbons, cords, lace.

The combed spinning system after carding operations provides for additional combing of fibers on combers. At the same time, short fibers and small debris are removed, long fibers are straightened and oriented parallel to each other. Further thinning of the resulting tape is carried out, as in the carded system, by stretching on subsequent machines. This system is used to spin yarn that is stronger, smoother, cleaner and finer. For spinning, fine-staple cotton, flax, thin long wool, silk-winding and silk-weaving production waste are used. The highest quality products are produced from combed yarn. However, the use of a combed spinning system leads to an increase in the cost of yarn.

Like the two previous systems, the apparatus spinning system includes carding, but unlike the above systems, there is no sliver formation.

Monofilament is a single thread that does not split in the longitudinal direction without destruction, suitable for direct use in the production of textile materials.

Further processing of primary threads can significantly change their appearance and properties. The result is twisted and textured threads, which are called secondary.

Twisted threads consist of several primary threads folded together longitudinally, connected by twisting into one. They have greater strength than primary threads and greater stability of other properties.

Twisted yarns include twisted yarns and twisted multifilament yarns.

Twisted yarn is single-twisted, obtained by twisting two, three or more yarns of the same length in one step, and multi-twisted, obtained as a result of two or more consecutive twisting processes. So, to obtain a two-twist yarn, first a part of the threads is twisted, and then, folding them together, they are twisted a second time.

In any of these cases, you can get:

a) plain twisted yarn, when the individual folded threads, supplied with the same tension, form a uniform structure of the twisted thread along its entire length;

b) reinforced, having a core (single yarn, twisted yarn, complex yarns, etc.), enveloped by different fibers (cotton, wool, flax, various chemical fibers) or threads, practically connected to the core due to twisting;

c) shaped twisted yarn, consisting of a core thread, twisted with a surge or effect, having a greater length than the core. The surge thread forms spirals on the yarn, knots of various shapes and lengths, ring-shaped loops, etc. Loops, knots and other effects are fixed on the core thread by a third fixing thread fed into the torsion zone at the speed of the core thread. The use of shaped twisted threads makes it possible to obtain fabrics with a beautiful external effect.

Twisted complex yarns, similarly to twisted yarn, are single and multi-twisted. In this case, simple complex twisted, combined and shaped threads can be obtained.

According to the degree of twist, twisted threads of different degrees of twist are distinguished. Threads of weak, or gentle, twist have up to 230 twists per 1 m of length. They are used in weaving as weft threads. Medium twist threads, or muslin, have 230-900 twists per 1 m of length and are used as warp threads in the manufacture of fabrics. High twist threads, or crepe, have up to 2500 twists per 1 m of length. Such threads are most often produced from raw silk or chemical complex threads. Fabrics made from crepe threads have a beautiful fine-grained, matte surface, i.e. they have a crepe effect. In addition, they are more rigid and elastic, which reduces their wrinkling.

According to the direction of twist, which characterizes the direction of the turns of the twisted thread, right-hand twist threads (Z) and left-hand twist threads (S) are distinguished (Fig. 12).

The properties of twisted yarn and multifilament yarns are greatly influenced by the combination of the twist direction of the primary yarn with the direction of subsequent twists. Twisted threads have the best properties, in which the directions of the primary and subsequent twists do not coincide (Z/S or S/Z). During the final twist in the direction opposite to the primary one, the constituent threads are untwisted until they are fixed by turns of re-twisting. Thanks to this they

form a dense thread of a rounded shape, uniform in thickness. As a result, the twisted thread receives greater strength, and products from it - greater wear resistance. textured threads are called, the appearance, structure and properties of which are changed by additional physical-mechanical, physical-chemical and other treatments. The threads have an increased volume, loose structure, increased porosity and extensibility. These features are a consequence of the increased crimpiness of the elements of their structure. These include textured (high bulk) yarns and textured multifilament yarns.

High-volume yarn with high elongation (30% or more) is obtained from synthetic multi-shrink staple fibers. High-shrinkage fibers, highly stretched during the manufacturing process, shorten during steaming and, due to friction, give low-shrinkage fibers an undulating crimp that increases the porosity, thickness and volume of the yarn.

However, textured multifilament yarns are of greater use in industry. There are three main ways to produce textured yarns.

The first method - thermomechanical - consists in imparting crimp to smooth complex synthetic threads by intensive twisting, fixing the twist by means of heat treatment, followed by untwisting. In this way, highly stretchable threads are obtained. Threads obtained in this way from nylon complex threads are called elastic. The large reversible extensibility of the elastic allows the production of products that should fit the human body well (socks, bathing suits, etc.). Textured threads from polyamide complex threads are called meron, from polyester - melan.

The second way - physical modification - giving smooth thermoplastic complex threads zigzag crimp, looseness by pressing (corrugating) them into special chambers with subsequent heat treatment. The resulting threads are referred to as threads of increased extensibility. The textured thread obtained by the pleating process is called corrugated. It is used to produce knitted fabrics for an assortment of outerwear, a variety of dress and suit fabrics.

The third way - aerodynamic - giving looseness and looseness to chemical threads of any kind by exposing them to a turbulent air flow in an unstressed state. This is how threads of normal extensibility are obtained. In this way, it is possible to obtain combined and shaped textured yarns from different types of primary yarns. Such looped threads obtained from polyamide are called aeron. They are used for the production of dress-suit, high-quality shirt fabrics.

According to the fibrous composition, the threads are homogeneous, mixed, heterogeneous, mixed-heterogeneous and combined.

Homogeneous is yarn, consisting of fibers of the same type (cotton, flax, wool, silk, chemical fibers); complex threads consisting of elementary threads of the same type; monofilament; twisted threads (twisted cotton yarn, twisted viscose thread, etc.); textured threads (nylon thread elastic, lavsan thread melan).

Mixed is yarn, consisting of a mixture of fibers of different origin, evenly distributed over the entire cross section along the yarn (for example, from a mixture of cotton and lavsan fiber, wool and nylon fiber, etc.).

Twisted threads are heterogeneous, containing homogeneous threads of different types (for example, wool yarn twisted with nylon complex thread), and mixed-heterogeneous (for example, semi-woolen yarn from a mixture of cotton and wool, twisted with nylon complex thread).

Combined are textured threads containing different types of textured threads and ordinary chemical complex threads (for example, the combined textured thread Tacon consists of an acetate textured thread twisted with a conventional nylon complex thread).

In terms of finishing and coloring, textile threads are harsh - without finishing; bleached; plain dyed; sour; boiled; melange - from a mixture of colored fibers; highlighted - from two or more multi-colored fibers; shiny, matte. Finishing and coloring of textile threads depend on their fibrous composition and structure.

test questions

1. What is yarn?

2. What is a multifilament thread?

3. What is monofilament?

4. What is twisted thread? What types of twisted threads do you know?

5. What is single-twist, double-twist thread?

6. What is the difference between plain twisted thread and fancy twisted thread?

7. What is reinforced twisted thread? How does it differ from plain and shaped twisted threads?

8. How do twisted threads differ in the degree of twist?

9. How do twisted threads differ in the direction of twist?

10. What is textured twisted thread? What are the features of textured threads?

11. What kinds of textured twisted threads do you know? What are the characteristics of these threads?

12. How are different types of textured threads produced?

13. How are threads distinguished by their fibrous composition?

14. What is a homogeneous, mixed, heterogeneous, combined thread?

15. What types of thread finishing do you know?

Basic properties of textile threads

The main properties that characterize textile threads include: thickness, twist, strength, extensibility, unevenness.

The thickness of textile threads, as well as fibers, is characterized by a linear density T (tex), which is determined by the already known formula

where m is the mass of the fiber, g; L - fiber length, km.

The linear density of a textile thread is determined by weighing the skein, i.e. a skein of yarn 100 or 50 m long, followed by recalculation of the total length of the threads in kilometers and the calculation of the indicator according to the above formula. The linear density of the thread can be calculated using the length of the thread in meters, according to the formula

T \u003d (1000t) / 1,

where m is the mass of the fiber, g; / - fiber length, m.

The thickness of fabrics, knitted and non-woven fabrics depends on the thickness of the threads. The use of thinner threads allows to obtain thinner fabrics and webs of textile materials.

The twist of the threads is determined by the number of twists or turns per 1 m of the length of the threads. This indicator is determined on the device - krutkomer. The twist of the thread depends on its thickness. The thicker the thread, the less number of twists per 1 m of thread length.

In order to be able to compare the degree of twist of threads of different thicknesses, an indicator is introduced, which is called the twist coefficient b. It is calculated according to the formula

where K is the number of twists per I m of the length of the thread; T-linear thread density, tex.

A low twist factor indicates that the thread is soft, neither tight nor elastic. High - that the thread is elastic, dense, thin, rigid.

An increase in the number of twists leads to an increase in the strength of the thread, but an increase in the strength of the thread has limits. .

Soft voluminous fabrics are obtained from soft threads of a gentle (small) twist. The use of high twist yarns makes it possible to produce dry, dense, elastic fabrics.

The strength and extensibility of the thread is characterized by the following indicators: breaking load and breaking elongation, which are determined when testing the skein, i.e. a skein of yarn 100 or 50 m long, on a tearing machine. The force at which the skein breaks shows the breaking load in centinewtons (cN), which characterizes the strength of the threads. At the moment of rupture, the breaking elongation, measured in millimeters, is also fixed.

Threads with reduced strength are worse processed in the weaving industry. Their frequent breakage is observed, which leads to a decrease in the quality of tissues. A small elongation of the thread at break indicates the rigidity of the thread, its resistance to stretching.

The unevenness or unevenness of the thread in linear density is an essential indicator of the quality of the thread. Roughness can be a consequence of the unevenness of the fibers in length, thickness, crimp and strength. It can occur at any stage of spinning production. The unevenness in linear density is determined visually or on special instruments. With the visual method, the threads are wound on screens of a contrasting color, and then the wound samples are compared unevenly with standards of varying degrees.

The smoother the threads, the less deviations are observed in thickness, strength, twist throughout their entire length.

Weaving

Fabric is a textile fabric formed by weaving two mutually perpendicular systems of threads on a loom. The process of fabric formation is called weaving.,

The system of threads located along the fabric is called the warp, the system of threads located across the fabric is called the weft.

Fabric production is carried out in three stages:

Preparing the warp and weft;

Making fabric on a loom;

Disposal of manufactured fabrics.

At the first stage, the warp and weft threads are prepared for the weaving process. The threads coming from the spinning mill are rewound into packages that are convenient for threading into a loom.

Warp preparation consists of the following operations: rewinding, warping, sizing and threading individual threads into the details of the loom.

The rewinding of warp threads from spinning cobs or skeins onto large cylindrical or conical bobbins is carried out on winding machines. At the same time, packages of great length are obtained, the threads are cleaned of impurities and their weak points are eliminated. Since the rewinding is carried out with a certain thread tension, weak points are detected by breaks. The broken ends of the threads are tied with a special weaving knot. On modern winding machines, where the winding speed reaches 1200 m/min, the tying of broken ends is carried out automatically. The warp threads, wound on large bobbins, go to warping.

The warping consists in the fact that the warp threads from a large number of bobbins (from 200 to 600 or more) are wound parallel to each other with the same tension on one large spool with flanges. Such a coil is called a warp shaft. All warp threads wound on the warping shaft must be of the same length. The warping operation is carried out on a special warping machine. Warping speed - 800 m/min. The warp threads from the warp shaft are fed to sizing.

Sizing is called gluing the warp threads with a special adhesive - dressing. Sizing gives the warp threads smoothness and strength. This is extremely important in order to prevent warp thread breaks during the weaving process due to abrasion on the loom part.

The sizing is cooked separately and then fed into the sizing machine. Dressing formulation includes adhesive, softening, antiseptic substances, wetting agents - substances that make the threads hygroscopic. Dressing formula may vary depending on the type of fabric.

The warp threads, passing under tension through the sizing machine, are dressed, squeezed, dried, separated one by one and, parallel and at an equal distance from each other, are wound on a shaft, which is called a weaving beam. The speed of movement of the warp in the sizing machine is from 12 to 75 m/min. Weaving machines for the production of fabrics for various purposes and fibrous composition have different widths. Therefore, a weaving beam of the appropriate width is installed on the sizing machine.

Before the weaving beam is installed on the loom, the warp is punched and tied. Probing, or probing the warp, is an operation in which each warp thread must be threaded in a certain order through the details of the loom: lamellas, heddle eyes and reed teeth.

A lamella is a thin metal plate with a round hole through which the warp thread is threaded. The lamellas are used to automatically stop the loom when the warp thread breaks. The number of lamellas is equal to the number of warp threads in the warp and, accordingly, the number of threads in the warp of the fabric.

The shaft frame, or shaft, is located across the entire width of the loom. It consists of two horizontal bars placed one below the other. Heddles with an eye in the middle of each heddle are vertically fixed between the planks. The warp threads are threaded through the eyes of the heddle - one through each eye. Shaft frames provide the formation of a shed for laying the weft thread. The number of heald frames depends on the type of weave of the fabric and ranges from 2 to 32. The number of heddles corresponds to the number of warp threads in the pile, but the order in which the threads are threaded into the eyes of the heddle depends on the weave of the fabric.

The reed also runs the full width of the loom and consists of flat metal plates fixed vertically on two slats. The metal plates are called reed teeth. The reed is used to nail the newly laid weft thread to the previous one, as well as to maintain a uniform, parallel arrangement of the warp threads during weaving. Each warp thread sequentially makes its way between the teeth of the reed.

The work of penetrating the warp threads into the holes of the lamellas, the eyes of the heddles and between the teeth of the reed is carried out on a special punching machine. The cleaning is carried out manually by two workers. The feeder feeds the warp threads one by one, and the parter pulls all the threads from the first to the last through the details of the loom with a special hook. With such an organization, 1000-2000 threads are sifted per hour.

Sweeping is carried out when refilling the loom to produce a new type of fabric or when replacing worn parts of the loom. If the same fabric will be produced on the loom, then in this case the piercing is not carried out, but the ends of the corresponding threads of the new warp from the new warp are tied (attached) to the ends of the old warp. When tying the ends of the warp, knotting machines are used with a knitting speed of 5000 knots per hour or more. To start the loom, the connected knots are carefully pulled through the holes of the lamellas, the eyes of the heddles, the teeth of the reed.

There are and are used automatic machines for punching warp threads.

Preparing the weft for weaving is a simpler process, which consists in winding the threads on special wooden shuttle spools and moistening the threads.

Rewinding onto shuttle spools is necessary if weaving is to be done on shuttle looms. This operation is performed on weft-winding machines at a speed of 300 m/min.

Moistening of the threads is carried out so that during the laying of the weft thread from the shuttle spool, several turns of thread are not wound at the same time, which leads to the formation of defects in the fabric. Moistening threads of different fibrous composition is carried out in different ways. Cotton and linen yarn is kept in rooms with high air humidity, woolen yarn is steamed, and silk and chemical threads are emulsified.

At the second stage, fabric is made on a loom (Fig. 13). From the weaving beam (1), the warp threads (2) go around the rock (3), lamellas (4), heddle eyes (5) and reed teeth (6) pass. When alternately raising and lowering the heald frames with heddles (5), the warp threads form a shed into which the weft thread (7) is laid. Berdo (6), due to the rocking movement of the batan mechanism (8), when moving to the right, nails the weft thread to the edge of the fabric (9) and moves to the left position. The resulting fabric, bending around the chest (10) and valian (11), is moved by the commodity regulator and wound on the commodity roller (12). The warp, unwinding from the weaving beam, is thus always in a taut state.

We already remember that in order to grow cotton, it receives huge doses of chemical fertilizers, pesticides and herbicides, many of which have long been banned in Europe.

1. Cotton is picked manually or mechanically, the grains are harvested, in the case of mechanical assembly, already at this stage the separation of the fiber from the rest of the plant occurs with the help of harmful chemicals.
2. Cleaning. Produced to separate the fiber from various debris.
3. Spinning and gluing.
   After cleaning, the fibers are spun into threads. The threads are glued to give them strength and to protect them from breaking during friction during the weaving or knitting process. To do this, the threads are immersed in solutions based on starch, synthetic resins and fats.
4. Whitening. The purpose of bleaching is to make the fiber as white as possible. Once upon a time, threads and fabrics were bleached in the fields, with the help of exposure to sunlight. Today, chemistry is used for this. Chlorine based products such as bleach, soda chloride or hydrogen peroxide.
5. Cleaning fabric from adhesive used in step 3. For this, chemicals are used.
6. Painting.
   In industry, only synthetic chemicals are used for coloring. There are more than 4,000 dyes, and they belong to different groups of chemicals.
   The use of chemical dyes is preceded by the use of a group of other chemicals: etchant, color accelerator, wetting agent, chelating agent, defoamer, catalyst, binders, thickeners, and many others.

   If you write in detail about dyes, you can write a whole book. We single out two groups only on physical grounds:

   • - pigment dye. Does not dissolve in water. Mainly used for dyeing synthetic fibres. Causes allergies, some of them are carcinogenic.
   • - soluble dyes. Used for natural and synthetic fibers. There are reactive, acidic, alkaline. Some belong to azo dyes.
7. Appretura. And you thought that the fabric was dyed, and that's it? Can you sew? In industry - nothing like it! The tissue must still undergo a series of operations called dressing. The purpose of these operations is to change the appearance of the fabric, to give it qualities that are valuable to consumers, sometimes to make the fabric heavier. Some finishes are purely mechanical (pilling, shaving, crimping), but most are chemical. Here are just the most common:
   * mercerization. Giving cotton a silky look and preparing for dyeing. The threads are soaked in a solution of caustic soda at a temperature of 0 degrees. The threads are then washed with an acidic solution to neutralize the residual caustic soda.
   * anti-creasing finish. Most often by applying formaldehyde resins.
   * bluing - to enhance the effect of whiteness. Numerous chemicals are used, derived from dibenzylidene, pyrazole, benzazole
   * anti-stall treatment. Used for wool. Most often with the use of formalin.

   Ekaterina Tarasova

It is worth mentioning that in Russian, cotton was originally called cotton paper. In many classical literary works, the expression "paper cap" can be found. And this is not at all a headdress made of paper that is familiar to us now, but just a wardrobe item made of cotton fabric. Therefore, the concepts of "cotton" and "cotton" are identical.

Where does cotton come from

It comes from cotton. It is a shrub reaching from 0.5 to 3 meters in height depending on the species. It has a spiral arrangement of leaves and a tap root system. About 40 species of cotton are known, but only a few of them are cultivated.

The bud blossoms into a flower, then self-pollination occurs, the flower turns into a box, which begins to ripen and opens (Hlopok tsvetok and Hlopok korobochka). Fibers germinated from seeds (Odin hlopchatnik) are released into the light.

Each fiber is a dead tubular cell. Its length is several thousand times greater than its width. It consists mainly of cellulose, but in its raw form it also contains some resins and waxes.

Cotton is thermophilic. The ideal temperature for it is around 30°C. Likes sun and moisture. Does not grow well in cool or hot weather. Among the leading countries in cotton exports are China, India and the United States.

Collection and processing of cotton

Cotton plantations are so extensive (Hlopkovoe pole) that cotton is harvested by mechanization. However, this method has the disadvantage of introducing unwanted parts of the plant into the crop. Manual assembly is much more accurate, but ten times less productive.

The collected cotton is cleaned. It happens like this. Cotton bales come from assembly points to the manufacturing plant. There they are opened and kept for a day for the so-called "flowering". After that, the cotton is loaded onto special machines, where it is loosened and cleaned of unnecessary impurities and seeds. The cotton then goes through a final cleaning process.

The resulting cotton fibers are twisted and pressed. The seeds are not thrown away: some of them will be sown again, some will go to oil, and the remaining oilcake will become livestock feed.

Cotton fabric production

Threads are spun from cotton fibers. They are glued with solutions based on resins, fats and starch in order to successfully withstand mechanical stress during further processing.

Next comes bleaching. Previously, sunlight served as bleach, but now more modern technologies are used - solutions, which include substances based on chlorine or hydrogen peroxide.

At the next stage, the previously used glue is washed off.

Sometimes the fabric is made from already dyed threads. In other cases, the bleached fabric, which during processing becomes completely hydrophilic (absorbing water with appetite), is dyed with special synthetic substances, of which there are more than one thousand in the industry.

During the production process, cotton can also be subjected to the so-called finishing, which is worth talking about in more detail.

Finishing is a series of operations that give the fabric the necessary consumer properties. There are mechanical varieties like shaving and brushing, but most are done using chemicals.

Blueing, for example, enhances the effect of whiteness. The name of the anti-creasing finish, which uses formaldehyde resins, speaks for itself. And, of course, mercerization is the soaking of fibers, threads or the finished fabric in caustic sodium at zero temperature. This operation gives the cotton silkiness, strength and ability to keep its shape.

Cotton or cotton, the fabric is durable, attractive appearance and wear resistance. Products made from it are pleasant to the touch, wash well and have excellent hygroscopic properties (cotton can absorb moisture up to 15-20% of its own weight without feeling wet). Cotton is the most popular material in the textile industry, and that probably says it all.