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One of the earliest natural fibers used by humans in textiles. The history of human use of wool can be traced back to the Neolithic Age, spread from Central Asia to the Mediterranean Sea and the rest of the world, and became the main textile raw material in Asia and Europe. Wool fibers are soft and flexible and can be used in the manufacture of textiles such as wool, wool, felts, felts, and other industrial and industrial textiles. Wool products are characterized by fullness, warmth and comfortable wearing. Sheep wool occupies a considerable proportion of textile raw materials. Countries with large world sheep wool production include Australia, the former Soviet Union, New Zealand, Argentina, and China. Sheep wool is divided into five categories according to fineness and length, such as fine wool, semi-fine wool, long wool, hybrid hair, and coarse wool. Chinese sheep wool varieties include Mongolian wool, Tibetan wool, and Kazakh wool. The main factors determining wool quality are fineness, curl, color, strength, and grass content.
Wool is an important raw material for the textile industry. It has the advantages of good elasticity, strong hygroscopicity and good thermal insulation. However, due to the high price, there is not much use for the production of nonwoven fabrics. Non-woven fabrics made from good wool are limited to a few high-grade industrial fabrics such as needle-punched paper-making blankets and high-grade needle felts. Generally used are short hair and coarse hair in wool processing, and the production of carpet backing cloth, sandwich layer of acupuncture carpet, thermal insulation material and the like by means of acupuncture and stitching. These types of wool have different lengths, high inclusions, poor spinnability, and difficult processing. The products can be chemically treated to improve quality.
Type wool has different classification methods and names. 1 According to histological structure: wool fiber can be divided into two types: medullary hair and unmyelinated hair. The medullary hair is composed of scale, cortex and medullary 3-layer cells; the medullary hair is medullary. The scale layer has a protective effect, the shape and arrangement of which can affect the ability of the wool to absorb moisture, build up and reflect light. The cortical layer is connected to the scale layer and is related to the strength, elongation and elasticity of the wool fiber. The finer the wool, the greater the proportion. The medullary layer is the main feature of the medullary hair. It is located in the central part of the hair and consists of polygonal cells filled with air and loose; the cross section is observed under the microscope, and it is easy to distinguish its development level. The more the medullary layer is developed, the thicker the fiber diameter and the lower the process value. 2 According to the growth characteristics, tissue structure and process characteristics of wool fibers: fluff, hair, two hairs, bristles and dog hair can be divided. The bristles are short hairs that grow on the face and the lower extremities of the limbs, and have no process value; the dog hair is a thick hair formed by the primary hair follicle in the early stage of embryonic development of the fine-haired lamb, and is gradually replaced by the medullary hair during lactation. Therefore, there are only three basic types of wool, hair, and two types of wool that can be used as raw materials for wool spinning. The fluff is distributed on the bottom layer of the coarse wool. The fine wool is composed of fluff, the fibers are fine, the average diameter is no more than 25 microns, the length is 5-10 cm, the softness is more curved, the elasticity is good, and the gloss is soft. Hairy or coarse hair, divided into three types of normal hair, dry hair and dead hair, forming the outer layer of coarse wool. Normal hairiness is 40 to 120 microns, with less bending and less flexibility. The medullary layer of fine hair is less developed, the cortex layer is relatively thick, the fiber elasticity is large, and the process value is high. The structure of the hair is the same as normal hair, but the tip is dry and lacks luster. The dead medulla is particularly well developed, thick and hard, fragile and fragile. The two types of hair are also called intermediate hairs, and their fineness and other process values ​​are between the fluff and the hair. 3 According to the fiber component contained in the hair: it can be divided into the same type of hair and mixed type hair. The former includes fine hair, semi-fine hair and high-generation modified hair, and its fiber fineness and length and other appearances are basically the same; the latter includes coarse hair and low-generation modified hair, and the wool is composed of fluff, two types of hair and hair, and the fiber thickness The length is inconsistent, the textile value is low, and it is mainly used as raw materials for blankets, carpets and felts.
The structure of the world wool is roughly 31.3% for fine hair, 42.3% for semi-fine hair and hybrid hair, and 26.4% for carpet hair.
The original Chinese sheep breeds belong to Mongolian sheep, Tibetan sheep and Kazakh sheep. The wool produced is of low quality and is a mixed type of wool. It is mainly used for carpet hair. Among them, Mongolian wool has both fine wool with a fineness of 52 to 58 and coarse wool. The wool is long, the hair is more than two types, the fiber is elastic and shiny, and it is the better quality of the mixed hair. The Xining hair produced in Qinghai is a good raw material for bed blankets and carpets. Kazakh wool is often mixed with yellow, brown and other colored hairs. The wool stocks contain more dry and dead hair. After the 1950s, on the basis of the introduction of fine wool sheep and semi-fine wool sheep from abroad, China has successively bred Xinjiang fine wool sheep and northeast fine wool sheep, which has improved the quality of wool.
The main component of chemical wool is keratin, which is composed of a variety of α-amino acid residues, which can be joined into a spiral long chain molecule containing carboxyl, amine and hydroxyl groups to form salts between molecules. Type bond, hydrogen bond, etc. The long chains are linked by a crosslink formed by a disulfide bond of cystine. The above chemical structure determines the properties of the wool. For example, when the long chain of the macrofiber of the wool fiber is stretched by the external force, the α-shaped spiral transitions to the β-shaped stretched shape, and when the external force is released and then returned to the α-type, the appearance thereof is excellent in elongation and resilience of the wool. The strong moisture absorption of wool is related to some groups on the long chain. Wool is more resistant to acids than alkali, because alkali easily decomposes disulfide groups in wool cystine, which damages hair quality. The oxidant can also damage the disulfide group and damage the wool.
The physical properties of wool mainly include fineness, length, bending, strength, elasticity, felting, hygroscopicity, color and gloss. Fineness is an important process characteristic for determining the quality and use value of wool fiber. It is expressed by the diameter of the fiber or the quality count; the smaller the fineness, the higher the count, and the finer the spun yarn. The length includes the natural length and the straight length, the former is the linear distance between the ends of the bundle, and the latter is the length measured by straightening the fiber. The elongation of fine hair is 20% or more, and the semi-fine hair is about 10 to 20%. In the case of the same fineness, the longer the wool, the higher the spinning performance and the better the quality of the finished product. Bending is widely used as a basis for the evaluation of wool quality. The curved and uniform shape of the wool, the spun yarn and the product are soft, elastic and warm. The fine hairs are many in number and the density is large, and the hairs of the coarse hair are waved or flat and have no curvature. Strong elongation has a direct impact on the firmness of the finished product. Strength refers to the stress of wool on fracture; elongation refers to the length that increases due to the action of the breaking force. The breaking strength of various types of wool varies greatly. The fineness of the same type of hair is proportional to its absolute strength, and the thicker the hair, the greater its strength. The more developed the medulla of the medullary hair, the worse its resistance to breakage. The elongation of wool is generally 20 to 50%. Elasticity keeps the product in its original form and is an indispensable feature of carpets and felts. The felting and hygroscopicity of wool is generally superior. The gloss is often related to the scale coverage of the fiber surface, the fine hair has a weaker ability to reflect light, and the gloss is softer; the luster of the coarse hair is strong and shiny. Weak luster is often caused by damage to the scale layer.
The processing steps are first processed into washed wool before the raw wool is woven. When processing, the wool is first selected to make the wool quality uniform, and then the wool is fluffed by opening the wool to improve the washing effect. Then, the wool is washed to form a stable emulsion of the lanolin, and the dirty impurities are floated in the washing liquid, and after processing, wet hair having a water content of about 40% can be obtained, and then dried. In the production, the combined machine is used for continuous operation to obtain the washed wool, and then enters the top manufacturing process; the top is drawn and thinned on the spinning machine and then enters the spinning process.
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