Porch 

Woven and nonwoven materials. Non-woven textile materials - what is it and what are the types. Mulch covering material

Reading time: 6 minutes

Non-woven fabrics do not require weaves of yarn for internal cohesion. In fact, they do not have an organized geometric structure. Nonwovens are the result of the relationship between two fibers. This gives nonwovens their own characteristics, with new or better properties (absorption, filtration) and therefore opens them up to other applications.

So , nonwoven fabric, what is it and where is it used? First of all, it is an independent product with its own characteristics and advantages, but also with disadvantages. Nonwovens are all around us and we use them every day, often without knowing it. Indeed, they are often hidden from view.

Non-woven fabrics can be made absorbent, breathable, drape, flame retardant, lightweight, lint free, injection molded, soft, stable, tough, tear resistant, water repellent if needed. Obviously, however, not all of the properties mentioned can be combined in one nonwoven material.

Application of nonwovens:

  • Personal and hygiene products such as baby diapers, feminine hygiene products, adult incontinence products, dry and wet wipes, and bra inserts or nasal strips.
  • Health care items such as operating room curtains, gowns and bags, face masks, dressings and swabs, bag liners, etc.
  • Clothing: pads, insulation and protective clothing, industrial work clothing, suits for chemical protection, shoe components, etc.
  • Household: napkins and rags, tea and coffee bags, fabric softeners, food wraps, filters, bed and table linens, etc.

  • Automotive: trunk lining, shelves, oil and cabin air filters, molded liners, heat shields, airbags, tapes, decorative fabrics, etc.
  • Construction: roof and tile lining, thermal and sound insulation, cladding, tightening, drainage, etc.
  • Geotextile: asphalt overlay, soil stabilization, drainage, sedimentation and erosion control, etc.
  • Filters: air and gas
  • Industry: cable insulation, abrasives, reinforced plastics, battery separators, satellite dishes, artificial leather, air conditioning.
  • Agriculture, home furnishings, leisure and travel, school and office, etc.

Origin and advantages of nonwovens

In fact, nonwovens were the result of recycling fibrous waste or second quality fibers left over from industrial processes such as weaving or leather processing. They were also the result of limitations in raw materials, such as during and after World War II. This humble origin, of course, leads to some technical and marketing pitfalls; it is also largely responsible for two still-lingering misconceptions about nonwovens: they are considered cheap substitutes; many also associate them with disposable products and for this reason view nonwovens as cheap, low quality products.

Not all nonwovens are limited to single use applications. Most products are intended for long-term end-uses such as gaskets, roofing, geotextiles, automotive or floor coverings etc. However, many nonwoven materials, especially lightweight ones, are actually used as disposable products or included in disposable items.

In our opinion, this is the main sign of efficiency. Waste suitability for disposal is only possible for economical products that concentrate on the essential required features and provide them without frills.

Most nonwovens, whether disposable or not, are high-tech, functional items, such as ultra-high absorbency or moisture retention, softness, outstanding barrier performance for medical applications in the operating room, or better filtration capabilities due to their pore size and distribution and etc. It is impossible not to mention also the non-combustible non-woven material.

They were not made for the purpose of their use, but to fulfill other requirements. They have mostly become disposable due to the sectors in which they are used (hygiene, healthcare) and due to their cost effectiveness. And recycling very often creates additional benefits for users.

Since disposable items have never been used before, there is a guarantee that they have all the necessary properties and are not reusable washed fabrics.

Raw materials for the production of nonwovens

Cellulosic man-made fibers of all lengths and degrees of purification and with clearly various properties are at the disposal of the non-woven bonded fabric industry.


All of them are characterized by the ability to absorb quite a large number of moisture. This recommends their use wherever this property is useful for the production of non-woven bonded fabrics, and/or the use of non-woven bonded fabrics is another prerequisite.

Nonwovens are textile fabrics made up of separated fibers that are properly positioned with use-oriented technologies. To ensure the performance of the finished product, they are connected. For this reason, the choice of fibers, and possibly binders, is of particular importance with respect to the fiber raw material and fiber dimensions. As a rule, they have a larger share in the creation of non-woven fabrics than is the case in textile fabrics from threads. Bonding agents can also affect the quality of nonwovens.

Fibrous materials used for nonwovens

Almost all types of fibers can be used to produce non-woven bonded fabrics. The choice of fiber depends on:

  • desired fabric profile;
  • economic efficiency for the production of non-woven bonded fabrics;
  • chemical fibers of both cellulose and synthetic origin.

Insofar as wide range of fabrics are either under development or already in production, it is impossible to name and describe all fabrics and fibers. The most important details will be given below.

  • vegetable fibres.

The most important constituent of plant fibers is cellulose, which is hydrophilic and hygroscopic. In addition to cellulose, plant fibers are also made up of several other substances that affect their properties. Cotton is the most important plant fiber used for the production of bonded non-woven fabrics.

  • fibers of animal origin.

Nonwovens-8

The field of non-woven bonded fabrics has become so broad that, to some extent, it includes almost all kinds of existing fibers. However certain types fibers began to predominate in certain areas.

The two main fiber types are polyamide 6, commonly known as perlon, and polyamide 6.6, commonly referred to as nylon to distinguish it from perlon. The number after the word "polyamide" indicates how many carbon atoms are present in each molecule that makes up the polyamide.

It is a material made from threads, fibers, films, in its manufacture traditional methods such as weaving or spinning are not used. The technology for the production of such canvases is simple, lower financial costs, the range of material is more diverse and has a low cost. Non-woven material has excellent performance. That is why non-woven fabric is today the main type of textile products.

Non-woven material is divided into the following types:

  • Textile
  • canvas-stitched
  • thread-piercing
  • fabric stitching
  • needle-punched
  • glued
  • combined
  • Batting
  • canvas-stitched
  • needle-punched
  • glued
  • household material
  • Technical material

Production of non-woven fabric

The properties of non-woven material directly depend on the raw materials, structure, production methods. Non-woven fabric is produced from the following chemical fibers:

  • viscose
  • polyester
  • polyamide
  • polyacrylonitrile
  • polypropylene

Also, it is possible to produce from recycled materials - waste of short, substandard fibers.

Technological process of manufacturing non-woven fabric

Raw material preparation

The initial stage of production, in which raw materials are loosened, impurities are cleaned, fibers are mixed, threads are rewound or binders are prepared, chemical solutions, hardeners.

Formation of the fibrous base

Fiber canvas is produced mechanically, at the same time, a comb of fibers (45-150 mm) is formed on a special carding machine. The fibers obtained in this way in the finished non-woven material are located in the longitudinal direction or longitudinal-transverse.

When forming the base in an aerodynamic way, the pre-combed fibers are transferred by air flow through the diffuser to the conveyor, where they are laid, forming a non-woven material (the fibers are not oriented).
Also, hydraulic or wet method, electrostatic, fiber forming are used for forming.

Obtaining a non-woven fabric (fiber bonding)

The fibrous base is fastened in several ways - physical-chemical, thermal bonding, physical-mechanical, combined. The first method is used to obtain bonded nonwovens. The physical-mechanical method includes: knitting, needle punching.

In order to obtain a non-woven fabric of high quality, increased strength and better deformation properties, a combined method is used.

Nonwoven fabric finishing

Non-woven fabric, depending on the further application, is produced unbleached, bleached, dyed.

The production of nonwoven material from chemical fibers has much in common with the production of geotextiles. When certain chemical additives are added to the non-woven, a product is obtained in terms of its properties and functions, as well as in its scope, similar to a geotextile.

Spunbond

Spunbond is one of the types of non-woven fabric produced by thermal bonding. Is non-woven polymeric material, made from polypropylene. According to the technology, thin threads are obtained from the molten polymer, which are then drawn in an air stream. The threads are fastened together using chemical impregnation, thermal bonding or needle-punching.

Spandbond has excellent characteristics that determine the scope of its application. The fabric is produced in a width of up to four meters, it is easy to cut. A wide range of density (10 - 600 g / sq.m.) and thickness, on which flexibility, strength characteristics, breathability determine the advantages of a non-woven fabric made of chemical fibers.

Material advantages

    • Wide range of applications due to easy handling and storage
    • Long service life, high strength, resistance to deformation, abrasion, creasing.
    • Low electrical conductivity, resistance to temperature fluctuations, heat resistance.
    • Resistant to various aggressive environments.
    • The ability to give the material any color at the stage of polymer melting.
      Areas of application of non-woven fabric.

The excellent properties and advantages of the material make it possible to use it in various industries. Applications depend on the density, dimensions of the web and even color.

Agriculture

Thermally bonded canvas of white or black color, with a density of up to 50 g/sq.m., is used as a covering and mulching material. For better protection from ultraviolet rays, during production, a special stabilizer is introduced into the raw materials. Withstands low temperatures, water and breathable.

Hygiene and medicine

A material is used with a density of up to 25 gr./sq.m. for the production of diapers, diapers. Density up to 60 gr./sq.m. for the manufacture of medical kits, including operating rooms, bandages and masks. Antibacterial, hydrophilic and hydrophobic additives are introduced into the raw materials.

Light industry

Produced disposable clothing, towels, tablecloths and napkins, bed linen, blankets, widely used as a lining and insulation material for tailoring outerwear, shoes, various leather goods, it is also possible to use in the manufacture of furniture. Non-woven fabrics of various colors and densities are suitable for light industry.

Chemical fiber nonwoven fabric is widely used in road construction, device drainage systems, as a filtering and insulating material, for insulation of rooms, roofs, floors.

Building membranes are produced from non-woven material, which, thanks to unique properties allow to extend the operational life of structures, various building structures and also reduce construction time.

Like any other product, chemical fiber nonwoven fabric must be purchased only from trusted manufacturers and suppliers.

Nonwovens

textiles made of fibers or threads joined together without the use of weaving methods (See weaving).

Large-scale industrial production of N. m. appeared in the 40s. 20th century Modern N. m. is one of the main types of textile products in many countries. In 1972, more than 3 billion tons of m were produced in the world. m 2.

Materials obtained by physicochemical methods. Most N. m., so-called. glued N. m., are produced by methods in which the connection of fibers is carried out with the help of binders (adhesives). The most common are glued N. m., the basis of which is the so-called. fibrous canvas (a layer of textile fibers, weight 1 m 2 which ranges from 10 to 1000 G and more). Most often, the canvas is formed mechanically ( rice. one ) from several layers of carding coming from the doffer drum of the carding machine (See Carding machine). The canvas is obtained by the aerodynamic method, in which the fibers are removed from the drum of the carding machine by an air stream and, to form the canvas, are transferred to a mesh drum (condenser) or to a horizontal mesh at a maximum speed of up to 100 m/min and more ( rice. 2 ). Canvas can also be obtained from an aqueous dispersion of fibers on a paper machine mesh (See paper machine).

Depending on the characteristics of the gluing of the fibers, several methods are distinguished for obtaining glued N. m.

The most common method is based on the impregnation of the canvas with a liquid binder - synthetic latex. The canvas is immersed in a binder bath or the binder is sprayed over the surface of the canvas. Sometimes impregnation is used, similar to drawing a pattern on the surface of a fabric by printing. The impregnated material is dried and processed in thermal chambers heated by hot air or infrared emitters. The canvas is usually formed from cotton, a mixture of viscose and polyamide fibers, or from waste textile production, including non-spinning ones. N. m obtained in this way (speed 50 m/min and more) are used as bead and gasket materials, for filters, as heat and soundproofing materials in the automotive industry, etc.

With the method of hot pressing, the gluing of fibers is carried out with thermoplastics (polyamides, polyethylene, polyvinyl chloride, etc.) under pressure up to 2 MN/m 2(20kgf / cm 2) at elevated temperatures, usually on special Calenders. Gluing is preceded by heat treatment of a layer of fibers containing a binder, which is introduced into the canvas at the stage of its formation (in the form of fusible fibers, mesh, threads, etc.) or into an already formed canvas (in the form of powder).

Upon receipt of N. m. using paper machines (speed 100 m/min and more), a binder (latexes, fusible fibers, etc.) is introduced into the mass supplied to the machine, or into an already cast web. Such N. m. are cheap, widely used in the manufacture of single-use products (bed linen for hotels, towels, tablecloths, dressings).

With the spunbond method, the synthetic fibers formed at the outlet of the spinnerets of the spinning machine pass through channels in which they are drawn in the air stream, and then, when laid on a moving conveyor, they form a web. The formed material is most often fixed with a binder; in some cases, the stickiness of the fibers themselves is used.

With the structure-forming method, N. m. can be obtained without the use of fibers: the canvas is formed as a result of the formation of condensation structures from solutions or aerosols of polymers (in the form of a porous, sometimes fibrous precipitate, which may contain fillers, then washed out) or by curing foam, etc. Such N m. "breathe" like a fabric. They can be used instead of cloth or paper in technology (for filters, etc.) and for domestic purposes.

Materials obtained by mechanical means. In the manufacture of canvas-stitched N. m. (Malivatt technology - GDR, "arachne" - Czechoslovakia, etc.) in a canvas moving through a knitting and stitching machine, the fibers are fixed as a result of stitching them with threads that fit and connect in the same way as in warp knitting on a knitting machine. Such N. materials are used as heat-insulating (instead of woven batting, etc.) or packaging materials, as the basis for the production of artificial leather (see Artificial leather), etc. The productivity of one unit is 3-8 m/min and more.

Thread-piercing N. m. (materials "malimo" - GDR) are obtained by flashing one or more systems of threads. These N. m. are used for decorative purposes, for beach and outerwear, towels, etc. Thread-sewn N. m.

Fabric-stitched fabrics are made by stitching a textile fabric with tufted yarn (material malipol, GDR), the use of which helps to improve the structure and properties of the fabric. For this purpose, fabric, “malimo” material, etc. are used. N. m. cm) - carpet yarn with needles that pull it through the fabric. When the needle moves back, the yarn is caught in the holder, resulting in loops. To fix the loops on the wrong side of the carpet, a binder is applied. Machine performance 5 m 2 /min and more.

With the help of knitting and stitching machines, N. m. is made without the use of threads (materials "Voltex" - GDR, "Arabeva" - Czechoslovakia, etc.). Such N. m. may consist, for example, of fabric and canvas obtained from long fibers. After pulling the fibers from the canvas through the woven frame, strong loops are formed on the wrong side of the N. m., and on front side- fluffy and high pile. Such N. and. used as an insulating pad in sportswear and demi-season coats, for the manufacture of hats, warm shoes and etc.

The most promising are needle-punched fabrics, which are made by entangling the fibers in linen and stitching it with notched needles. The material is pierced when the board with the needles moves down (to the stop). When it moves up, the material moves forward (the productivity of the machines is 5 m/min). Such N. mats are used as carpets, which successfully compete not only with woven, but also with tufted carpets, since they do not require yarn for manufacture. Needle-punched N. mats are also used as blankets, felts for paper machines, filters, etc.

N. m. also include felting and felt textile materials (see Felting) , in the manufacture of which the ability of wool fibers to felting is used (during mechanical or heat-moisture processing). The structure of such N. m. sometimes enter the framework of the fabric. The technology for their production has a long history (in this way, for example, felt boots are obtained).

Lit.: Technology for the production of non-woven materials, M., 1967; Tikhomirov V. B., Chemical technology for the production of non-woven materials, M., 1971; Perepelkina M. D., Shcherbakova M. N., Zolotnitskaya K. N., Mechanical technology for the production of nonwoven materials, M., 1973.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what "Non-woven materials" is in other dictionaries:

    Cloths and products made from fibers, threads and other types of textile materials (sometimes in combination with non-textile, such as films) without the use of spinning and weaving. Nonwovens: carpets, blankets, fabric substitutes… … Big Encyclopedic Dictionary

    Nonwovens- NON-WOVEN MATERIALS, textile materials from fibers and threads, made without the use of weaving processes. Non-woven products: carpets, blankets, insulation pads for clothes, shoes, paper machine felts, filters, etc… Illustrated Encyclopedic Dictionary

    This article should be wikified. Please format it according to the rules for formatting articles ... Wikipedia

    Textiles made of fibers or threads joined together without the use of traditional methods weaving. Industrial production of nonwoven materials appeared in the 40s. 20th century Modern nonwovens are one of the main products ... ... Encyclopedia of technology

    nonwovens- Textile materials made from natural and chemical fibers without the use of weaving methods (mechanical, physico-chemical and combined methods). The production of nonwoven materials includes the preparation of the base (canvas, ... ... Textile glossary

    Nonwovens- textiles made from fibers or threads obtained without the use of weaving. For the production of N. M., low-grade and non-spun fibers, textile production waste can be used, which leads to a high economic ... ... Encyclopedia of fashion and clothing

    Cloths and products made from fibers, threads and other types of textile materials (sometimes in combination with non-textile materials, such as films) without the use of spinning and weaving. Nonwovens: carpets, blankets, substitutes… … encyclopedic Dictionary

    Cloths and products made from fibers, threads and/or other types of materials (textiles and their combinations with non-textiles, such as films) without the use of spinning and weaving. Compared to traditional production methods in the textile industry ... ... Chemical Encyclopedia

    Text. materials made from nature. and chem. fibers without the use of weaving methods (mechanical, physical, chemical and combined methods). The production of N. m. includes the preparation of a base (canvas, a system of threads, a film of fibrous structure, etc.), ... ... Big encyclopedic polytechnic dictionary

    Non-woven textiles are materials made from fibers or threads joined together without the use of weaving methods. Contents 1 The history of the development of the nonwovens industry 1.1 Classification ... Wikipedia


Nonwovens are called textile fabrics made from one or more layers of textile materials (sometimes in combination with non-textile materials), structural elements Ry which are fastened different ways.

The basis of non-woven fabrics can serve as a fibrous canvas, a system of threads, fabric or knitted fabric and various Them combinations. AT non-textile materials, in particular, polymer films or nets, can also be used as structural elements. The fastening of the structural elements of non-woven fabrics is carried out in various ways: knitting with threads and fibers, needle punching, gluing, welding, felting, etc.

A variety of methods for the production of non-woven fabrics is the basis for their classification (Scheme 1.5). According to the bonding methods, non-woven fabrics of three classes are distinguished: bonded by mechanical, physico-chemical and combined methods. The classes of paintings, in turn, are divided into subclasses. Further, the division of the canvases is carried out into groups depending on the type of material base: canvas, thread system, carcass and their difference in combination.

TThe structure of non-woven fabrics. The structure of nonwoven fabrics is largely determined by the method of production. The technological process of manufacturing non-woven fabrics is

Two stages: preparation of the base (canvas, thread system, fabric No. etc.) and its fastening.

Lj The preparation of the fibrous web consists in selecting a mixture of rolocone and threads, loosening, mixing, cleaning and carding the fibrous mass and shaping the web. For production

The structure of non-woven fabrics is widely used natural fibers and threads (cotton, wool, linen) and chemical (viscose, nylon, lavsan, nitron, etc.) in various combinations, which makes it possible to obtain materials with various properties. In the production of non-woven fabrics of some types, fibers of both standard length and short (at least 3 mm), spinning production waste, waste fibers are used, which makes it possible to use fibrous raw materials with great economic effect. For the formation of fibrous mass, depending on the type of processed raw materials, machines are used in the opening, scutching and carding departments of spinning production.

The formation of the canvas can be carried out in several ways: mechanical, aerodynamic, hydrodynamic and electrostatic. With the mechanical method, the webs from the carding machines are stacked on top of each other with the help of conveyor belts.

Depending on the direction of laying the battens, there are canvases with different orientations of the fibers in them: longitudinal, longitudinal-transverse, diagonal. All oriented webs have a layered structure.

With the aerodynamic method, the fibrous web is formed by an air flow from individual fibers on the surface of a mesh drum (condenser) or a conveyor belt. The hydrodynamic method of formation is based on the dispersion of fibers in a liquid and their subsequent deposition and placement on mesh conveyor belts. In the electrostatic method, the formation of a fibrous web occurs by moving and depositing electrostatically charged fibers in electric field. With aerodynamic, hydrodynamic and electrostatic methods of formation, layerless canvases are obtained with a non-oriented, chaotic arrangement of fibers.

The nature of the location of the fibers in the canvas largely determines many of the physical and mechanical properties of nonwoven fabrics, in particular their strength in the longitudinal and transverse Directions. Often, to increase the strength of the fibrous canvas, a frame is placed on its surface or between layers in the form of a transverse system of threads, a mesh of warp and weft threads stacked on top of each other, a rare fabric or knitwear. In the preparation of systems of threads, fabrics, knitwear, different kinds Yarns and complex yarns. These types of base non-woven fabrics are made, respectively, at spinning, weaving and knitting enterprises. Structural elements of the basis of non-woven fabrics are fastened by mechanical, physico-chemical or combined technology.

mechanical technology bonding is based on the impact of the working bodies of the equipment on the processed fibrous material. In this case, knitting-stitching, needle-punching, jet and felting methods of connection are used, of which the knitting-stitching method is most common.

The knitting and stitching method consists in knitting the base in the form of a canvas, a system of threads, fabric, etc. with threads. The warp is knitted with threads on a knitting machine, which is a type of knitting warp knitting machine, using grooved needles. Hooks of needles for simplification of piercing are pointed. For knitting the base of non-woven fabrics, chain weaves, tights, cloth, charme, sirloin, plush, combined, etc. are used. Canvas-stitched non-woven fabrics are produced on knitting-and-stitching machines. The fibrous canvas (Fig. 1.46) is fed into the knitting zone with the help of a conveyor belt. Grooved needles pierce the fibrous canvas from the bottom up and capture the knitting threads that feed the eyelets. The threads are unwound from the beam. During the reverse stroke, the slotted needles pull the threads through the canvas, forming a warp-knitted weave. The finished fabric is wound on a commodity roller. A canvas-stitched fabric is a canvas enclosed inside a rare knitted weave, on the front side of which there are looped columns, and on the wrong side - zigzag broaches (Fig. 1.47). Its variety is a canvas, which is a fibrous canvas knitted with the fibers of the same canvas. To obtain such a fabric of sufficient strength, it is necessary that the length of the fibers in the canvas be 60-120 mm, and the orientation of the fibers is predominantly transverse.

Rice. 1.46. Scheme for obtaining a non-woven fabric knitting-proshpv-

New way:

1 - conveyor belt, 2 - Canvas; 3 - pavoi; 4 - knitting thread; 5- ears; b - groove needle; 7- canvas-stitched gu-

Lotno; 8 - commodity kalik

■ <А .|1t«.I. H. .V.-I. I I IG *

Rice. 1.48. Thread-sewn non-woven fabric

There are one (weft) or two (weft and warp) systems of threads, which are knitted by the third system (Fig. 1.48).

Non-woven thread-stitched fabrics can be produced by plush weave, which makes it possible to obtain terry and tufted fabrics.

Frame-stitched non-woven fabrics are obtained in a similar way by knitting loops with elongated broaches on a frame base. In this case, using threads of various types, it is possible to produce materials such as terry, plush, artificial fur, etc. Fabric (fabric-stitched fabrics), knitwear, and non-woven material are used as a frame base. A variety of frame-stitched canvases are fabrics in which the frame material is knitted with the fibers of the canvas laid on the frame. As a result, fibrous loops are located on the wrong side of the fabric, and a continuous fibrous covering is formed on the front side. In this way, it is possible to obtain lining materials for clothing and artificial fur.

The needle-punched method for producing non-woven fabrics consists in the fact that the fibrous canvas is pierced (punched) with special needles that have a trihedral, square or diamond-shaped blade, on the edges of which there are notches (Fig. 1.49). The fibrous canvas (Fig. 1.50) is fed by means of a conveyor belt to the needle punching area between the Laying and Cleaning tables. The tables have holes for the passage of needles and fixing the position of the canvas when pierced. The needles are fixed on a needle board that moves up and down vertically.

Passing through the canvas, the needles grab the fiber bundles with their notches and drag them through the thickness of the canvas. As a result, in the struct Toure canvas (Fig. 1.51) change the location of the fibers, their orientation. In places of punctures, bundles of fibers are formed, located perpendicular to the plane of the canvas; with the help of these beams

Rice. 1.49. Needle used to produce non-woven fabrics by needle punching

Cove is the binding of the structural elements of the canvas. The fibers are arranged in a bundle in the form of a funnel, expanding at the point where the needle enters the canvas. The bonding strength of the web depends on its thickness and the frequency of punctures: the greater the thickness of the web and the frequency of punctures (and hence the frequency of the fiber bundles), the higher the bonding strength.

The jet method of bonding a fibrous web is based on the action of thin jets of liquid or gas on it, which are ejected from nozzles at a pressure of 1.4 - 32.4 MPa at a speed of 15 - 30 m/s. The most common use of water jets. The canvas is placed on a mesh conveyor and subjected to one-sided or two-sided plow action! water, resulting in entanglement of the fibers in the canvas with the formation of a sufficiently strong material. The supply of water jets can be continuous and pulsating. The bonding strength of canvases depends on the pressure, the number of nozzles per unit area of ​​the canvas, and the speed of its supply to the inkjet device. The structure and appearance of the non-woven material is greatly influenced by the structure of the substrate - the grid on which the canvas is placed. If the substrate has a relief structure, then the water jets, hitting the reliefs, are deflected and act on the canvas for the second time. As a result, the binder compacted fiber bundles are located not only vertically to the surface of the canvas, but also horizontally or obliquely. In this case, the fibers that have fallen into the recess of the substrate are more entangled and form patterned effects on the surface of the web.

Needle-punched and inkjet methods can be considered as ways to pre-bond webs, since the resulting webs have significant elongation and a large proportion of irreversible deformation.

Rice. 1.50, Scheme for obtaining a non-woven fabric by a needle-punched method -

1 - canvas: 2 - transporting LESH-i. 3 ~ laying table; 4 - cleaning table; 5 - needles; 6 - needle board-1

Rice. 1.51. Fiber Orientation in Needle Punched Nonwoven Fabric

The felting method for the production of non-woven fabrics is one of the oldest methods for producing textile materials. It consists in the compaction of the fibrous mass under the combined action of moisture, heat and mechanical load. The most durable and dense fabrics are obtained from wool fibers - the only type of fiber that has the properties necessary for this method; elasticity, crimp and the difference in tangential resistance along and against the flakes of the fiber surface. The use of other types of fibers is inefficient: the fabrics obtained are easily stratified. In the production of non-woven fabrics, the felting method usually processes a canvas with a carcass laid inside from a system of threads.

Physical and chemical technology The production of nonwoven fabrics is based on the adhesive or autohesive bonding of canvas fibers, a system of threads and textile materials. Adhesive bonding (gluing) of fibers and threads is provided by polymer binders (adhesives). The autohesive connection of fibers and threads at the points of contact occurs under conditions that provide softening of the surface layer of the fibers and their adhesion (welding).

For the production of non-woven fabrics, polymeric binders are used, the share of which in the fabric is about 0.3. They are the same important component of the non-woven fabric as fibers and threads, and provide a strong connection of structural elements. Polymers of Lrex types are used as binders: thermoplastic, thermosetting and based on kau - 1 "Chukov (rubber).

Thermoplastic binders are polymers that, when heated or dissolved, soften and stick together the structural elements of the base. These include polyester - | Linen, polyvinyl acetate, polyvinyl alcohol, polypropylene, roleurethanes, cellulose derivatives, etc. Thermoplastic binders are used in various forms: polymer solutions, aqueous dispersions, powders, fibrids, fibers, films, meshes. They are preliminarily applied to fibers from a melt or solutions (combined fibers) or introduced into the composition of the fibers during their [spinning (bicomponent fibers).

K, Thermosetting binders harden as a result of chemical reactions with the formation of an irreversible three-dimensional structure - ■rt. They are based on phenol-formaldehyde, epoxy, polyester and other synthetic and natural resins. In the production of household non-woven fabrics, thermosetting binders are rarely used, as they give the fabrics increased rigidity.

Rubber-based binders harden as a result of vulcanization. They are widely used in the form of aqueous dispersions of synthetic rubbers (latexes) with the addition of thermosetting binders.

Gluing with liquid binders is one of the most common methods for obtaining glued nonwoven fabrics. It consists of the operations of impregnating the base (canvas, thread systems, etc.), drying and heat treatment. The introduction of a binder into the base of the nonwoven fabric can be carried out in various ways. When the canvas is completely immersed in the solution, followed by squeezing, the binder is evenly distributed throughout the base with the formation of the maximum number of bonds between the fibers, which gives the materials increased rigidity. During padding, the canvas is passed between two rollers of the machine, where a liquid binder is fed. With this method, a foamed binder is often used, which gives the finished web increased elasticity, porosity, breathability and reduces its surface density. Impregnation with a binder sprayed over a moving web, using vacuum suction to penetrate deeper into the structure, results in a reduction in the number of glues and a softer web.

A similar effect can be achieved by impregnating the canvas by printing - local application of a thickened binder to the canvas in a specific pattern in the form of dots, rings, loops, rhombuses, etc. Subsequent heat treatment promotes strong bonding of the structural elements of the non-woven fabric as a result of rubber vulcanization or softening of the thermoplastic binder . However, during drying and heat treatment, migration of binder particles to the surface layers is possible, which can cause delamination of the fibrous web.

Bonding with solid binders is based on fastening the fibers and threads of the base of the nonwoven fabric with thermoplastic binders when heated, which are introduced into the base structure at the stage of preparation of the fibrous mass in the form of powder, low-melting fibers, fibrides, combined and bicomponent fibers; when forming a canvas - in the form of frame elements: films, nets, systems of fusible threads; into the finished canvas - in powder form. Heating is carried out by thermopressing or thermocontact welding over the entire area; if in separate places, then engraved shafts or electrodes of various shapes are used. When the powder particles are heated, it is easy
fusible fibers and threads, fibrids, films melt and form bonds between the fibers and threads, with part of the binder remaining outside the bonds. Unlike them, combined and bicomponent fibers do not lose their shape when heated, but only melt over the surface and form gluing only at the points of contact of the fibers, creating an ideal point structure of the glued canvas. By changing the thickness of the fusible sheath of combined fibers, their ratio with ordinary fibers in the canvas and the pressing mode, it is possible to obtain materials of various structures: from bulk porous materials to materials consisting of a continuous film of binder reinforced with fibers.

The papermaking method for producing nonwoven fabrics is based on the formation of a fibrous web by a hydrodynamic method from a suspension of fibers containing a binder. The technological process consists of the preparation of a suspension of fibers, the casting of the web on a paper machine, dehydration, drying and heat treatment. This method is very promising, as it allows the use of any raw material, short fibers (2 - 6 mm) and high-performance equipment. At present, medical fabrics are obtained in this way (for linen, gowns, napkins, etc.).

The spunbond method for the production of nonwoven fabrics consists in the aerodynamic formation of a fibrous web directly from a melt or polymer solution (Fig. 1.52). Thin streams of polymer come from the holes of the spinneret into the blowing shaft, where, under the influence of the air flow, the threads are pulled and hardened. From the shaft, the threads are fed to a conveyor belt, where a fibrous web is formed. There are two options for forming the canvas: hot and cold. In the hot mode, the threads at the time of laying are softened to such an extent that the formation of glues is possible at the points of contact due to autohesion without the introduction of a binder. However, in this case, the mechanical properties of the filaments are very low, because due to the weak drawing and the relaxation that occurs during laying, the structure of the fibers is poorly oriented. In a similar way, an adhesive web is obtained for gluing Clothing Details. When cold forming

Rice. 1.52. The scheme for obtaining a non-woven fabric by a spunbond method:

1 - transporting mite; 2 - blower shaft; 3 - streams of polymer; 4- die
In the fabric of the canvas, the threads completely harden by the time of laying, so a binder is introduced to fasten them, and then heat-fixing is carried out.

The spunbond method for producing nonwoven glued fabrics is one of the most promising. By Experts predict that in the coming years, the volume of production of nonwoven fabrics by the spunbond method will reach 30% of the total volume and will continue to increase in the future. This is due to the high productivity of the plants, the simplification of the process of forming the canvas, the use of chemical threads and the possibility of producing a wide range of canvases.

Combined technology The production of nonwoven fabrics is based on a combination of mechanical and physico-chemical bonding methods. Options for combinations of methods can be different: for example, preliminary needle-punched or jet bonding of the canvas and subsequent connection with its binder; stitching the carcass with pile threads and fixing them with binders, etc. The combined method includes blasting a canvas containing low-melting fibers, fibrids or bicomponent fibers with hot air or water. In this case, not only the entanglement of the canvas fibers occurs, but also their thermal bonding.

The main characteristics of the structure. Until now, there is no well-established classification of the characteristics of the structure of nonwoven fabrics, which is associated with the constant improvement of their manufacturing technology and the emergence of new types of structures. Therefore, at present, the structure of nonwoven fabrics is characterized by the parameters of the structure of their base (fibrous canvas, systems of threads, fabric, knitwear, etc.) and the parameters of the fastening elements (piercing, gluing).

The structure of the fibrous canvas is determined by the linear density of the fibers and threads, the degree of their straightening and orientation in the canvas, the number of layers of batting. The degree of straightening of the fibers is characterized by the coefficient of curvature WITH, Which is the ratio of the true length L„ of the fiber to the distance a between fiber bonding points or fiber ends:

The orientation of the fibers in the web is estimated by the angle p of the fiber to the longitudinal direction of the web. Since the location of the fibers in the canvas is not the same, it is customary to determine the indicators of these characteristics for a large number of fibers and plot their distribution curves, according to which it is possible to establish the predominant value of the curvature coefficient and the orientation angle.

If systems of parallel threads, fabric or knitwear serve as the basis of a nonwoven fabric, then the characteristics of the structure of this fabric are the number of threads along the length and width, as well as the generally accepted characteristics of the structure of the fabric and knitwear.

The method of fastening the elements of its base has a significant influence on the nature of the structure of the non-woven fabric. With the knitting-stitching method of fastening, the characteristics of the stitching structure are similar to the characteristics of the knitwear structure. This is the number of loops in length Px and width Fri fabrics on a conditional length of 50 mm, the length of the thread in the loop / p. In addition to them, the length of the sewing thread L, mm, per 1 m2 of the web is determined:

L = 0.4 YADLSh/P

And the work Y,%, threads:

Y \u003d 100 (1, - L2 )/L,

Where Lx - thread length, mm; b7 is the length of the section of the fabric from which the thread is taken out, mm.

The structure of the needle-punched fabric is characterized by the frequency of punctures per 1 cm2.

A distinctive feature of glued non-woven fabrics obtained by physical and chemical technology is the presence of zones of bonding (gluing) of fibers or threads with binders. The structure of the gluings is characterized by the design, appearance, size, distribution and number of fibers in the gluing. There are several types of glues found in the structure of nonwoven fabrics.

Contact gluing (Fig. 1.53, a) is formed by a layer of binder between the fibers at the points of their contact. They are characterized by minimal size and low strength; occur mainly when combined and bicomponent fibers, fibrids are used as a binder and during hot forming of a spunbond web.

Gluing-couplings (Fig. 1.53, b) form a stronger connection, but less mobile than contact ones, since the film is connected

Zuyushego envelops the fibers at the intersections. These gluings occur when canvases are bonded with liquid and solid binders.

Lamella gluing in the form of plates (Fig. 1.53, in) are, as it were, couplings increased along the length of the fibers; they sharply limit the mobility of the fibers in the joint. Lamella gluing occurs mainly when using latexes as a binder.

Aggregate gluing fastens more than two fibers arranged in parallel (Fig. 1.53, G) or chaotically (Fig. 1.53, e). With a parallel arrangement of fibers, the gluing design combines a contact riveting and a sleeve, such gluing has maximum strength and minimum mobility. With a random arrangement of fibers, the bonding strength is slightly lower.

In non-woven fabrics, gluing of various types can occur simultaneously, the proportion of which depends on the type of fibers, the structure of the canvas, the type of binder, and the fabric manufacturing conditions. There are three main types of structure of non-woven glued materials: segmented, agglomerated and dotted.

In the segment structure (Fig. 1.54, a) the main share is made up of aggregate and lamellar glues, which tend to form a continuous three-dimensional network structure inside the material. In materials with a segment structure, the properties are determined to a greater extent by the properties of the binder than by the properties of the fibers, the mobility of which is extremely low. The materials are characterized by rigidity and low permeability.

The agglomerate structure (Fig. 1.54, b) is characterized by the presence of predominantly gluing-couplings, as well as random accumulations of a binder of various shapes. Compared to the segmental structure, it is more mobile and less rigid.

In a dot structure (Fig. 1.54, in) there are contact gluing and gluing-couplings. The binder is most rationally distributed in it. The properties of a non-woven fabric of a dotted structure are determined by the properties of the constituent fibers, the nature of the location and the strength of the gluing. Such canvases are characterized by softness, mobility, good permeability.

The structure of glued non-woven fabrics is characterized by the proportion of the binder in the total mass of the fabric and the coefficient of use of the binder Xl, which is defined as the ratio of mass Moscow or volume USKYA binder in gluing to the total mass MSV Or the volume VCtt of the binder in the web;

To= L//M = V /V

Textile materials consisting of fibrous canvas or threads bonded in various ways are called non-woven materials.

There is no spinning and weaving in the technological process of obtaining non-woven textile materials. Only some nonwovens are made from yarn, but without the weaving process.

The range of nonwovens is expanding as they are much cheaper than fabrics. Non-woven materials are used for the production of clothing and haberdashery, furniture, cars, shoes.

Nonwovens are produced mainly in three ways:

Mechanical (felting-felt, needle-punched production methods);

Physical and chemical (adhesive sheets);

Combined (knitting and stitching and glue, needle-punched and glue, etc.).

Raw materials for the production of non-woven materials are cotton, wool, waste of natural fibers of textile production, artificial and synthetic threads.

By purpose, non-woven materials are divided into household, cleaning, container, packaging, shoe.

Non-woven materials (non-adhesive) have good hygroscopicity, air permeability and heat-shielding properties. They are resistant to deformation, soft to the touch, cheaper than fabrics. The disadvantages of nonwoven materials are their low strength and instability to abrasion.