Non-woven textiles

Nonwoven textiles are materials made of fibers or threads that are joined together without the use of weaving methods.

History of the nonwovens industry
Since ancient times, two types of nonwovens have been known: batting and felt.

The 1930s are considered to be the beginning of the era of modern nonwovens. The first samples were created in Europe. These were fabrics made of viscose fibers fastened together by chemical binders. A little later, other methods of their production were mastered, differing both in the type of raw material and in the method of fastening.

Classification
Nonwovens are divided into three classes depending on the method of bonding

mechanically fastened;
bonded by physicochemical method;
bonded in a combined way

Raw materials
Nonwovens are produced from both natural (cotton, linen, wool) and chemical fibers (e.g. viscose, polyester, polyamide, polyacrylonitrile, polypropylene), as well as recycled fibrous raw materials (fibers regenerated from flaps and rags) and short-fiber waste from chemical and other industries.

Acquisition technologies
The main technological operations for the production of nonwovens are:

Preparation of raw materials (loosening, purification of impurities and mixing of fibers, rewinding of yarns and yarns, preparation of binders, chemical solutions, etc.).
Formation of a fibrous base.
Bonding of the fibrous backing (direct production of non-woven fabric).
Non-woven fabric finishing.

Methods for producing nonwovens
The main stage in the production of nonwovens is the stage of bonding the fibrous base, obtained in one of the following ways: mechanical, aerodynamic, hydraulic, electrostatic or fiber-forming.

Methods of bonding non-woven fabrics:

Chemical or adhesive bonding (adhesive method) – the formed web is impregnated, covered or sprayed with a binder, the application of which can be continuous or fragmented. As a rule, the binder is used in the form of aqueous solutions, in some cases organic solvents are used.
Thermal bonding – This method takes advantage of the thermoplastic properties of some synthetic fibers. Sometimes the fibers that make up the nonwoven fabric are used, but in most cases, a small amount of fibers with a low melting point ("bicomponent") is specially added to the nonwoven fabric at the molding stage.
Mechanical (frictional) bonding:

needle-punched method.
knitting and stitching method.
hydrojet method (Spunlace technology).
Spunlace technology
Spunlace technology was introduced in the 4s, but was first officially introduced by DuPont in 1960 (Sontar's® material) and was the result of hard work by DuPont and Chicopee. In the 1973s, inkjet technology took a significant step forward and became more productive[1990] and affordable for many nonwovens manufacturers.

Hydroplexing technology is based on the interweaving of material fibers with high-speed water jets under high pressure. Typically, the web is fastened to a perforated drum by means of high-pressure water jets from nozzle beams. Due to these jets, the fibers of the canvas are connected to each other.

The leader and innovator in the field of spunlace technology is Rieter.

Needle punched materials
With this technology, the canvas is formed from cut ("staple") fiber or from continuous threads ("filaments") obtained from a polymer melt. The fibers are formed from the polymer by the spinneret blowing method and almost simultaneously laid in the canvas. Single fibers of finite length ("staples") in the carding machine are oriented mainly in the horizontal direction and are formed into a canvas ("fleece").

Subsequently, the laid canvas undergoes the procedure of fastening mechanically by punching the canvas with needles of a special design of triangular cross-section, from one or both sides. The purpose of needle punching is to compact the stacked filaments ("staples") and entangle them with each other. At this stage of the technological process, the blade acquires its strength properties, which may vary depending on the nature of further application of needle-punched fabrics. If necessary, the pierced canvas undergoes a procedure of additional thermal bonding with the help of a calender. Also, for needle-punched fabrics used as a basis for polymer coatings (linoleum, artificial leather, cable products), additional heating in industrial furnaces, the so-called "shrinkage", is used.

Needle punching technology is very popular, since the product obtained by this method of production has a unique combination of strength and consumer characteristics.

Industries of application of needle-punched non-woven fabrics: geotextiles, filters, linoleum, carpeting, automotive, upholstered furniture, artificial leather, clothing, footwear industry, haberdashery.

Spunjet Technology
A technology in which the final fixation takes place with the help of high-pressure water jets. The strength of the finished material is incomparably higher than that of non-woven fabric fastened in any other way.

Thermal bonding technology
The essence of the technology is the effect of high temperatures (up to 180°C) on low-melting polyester fibers mixed with other chemical fibers, by means of multi-section furnaces, in which the jacket of light-melting fibers is melted and bonded to other fibers in a glue-free way.

Strutto technology
"Strutto" refers to the vertical laying of fibres in the production of nonwovens.

AirLay Technology
AirLay technology is a fiber formation system that is ready for needle punching and heat setting. This technology is intended as a replacement for outdated carding machines and canvas layers. The capacity of such a line allows to produce about 1500 kg of finished products per hour. The weight of the material produced varies from 150 g/m² to 3500 g/m². The uses of AirLay technology are diverse. For example, automotive, agriculture, upholstered furniture, construction, apparel, and packaging.

Airlaid Technology
Airlaid is a type of nonwoven fabric that gets its name from the way it is produced – air laying (laid). It is a non-woven fabric made of natural softwood cellulose, bicomponent staple fiber and additives. Unlike the conventional fiber manufacturing process, airlaid does not use water as a medium to produce fiber.

Aerodynamics Technology
In the aerodynamic method, the combed fibers are carried away by the air flow and transferred through a channel (diffuser) to a mesh drum or conveyor, where they are laid to form a canvas of a non-layered structure (non-oriented arrangement of fibers).