Wool Yarn Knowledge
Wool yarn is mainly composed of protein. The use of wool by humans can be traced back to the Neolithic Age, spread from Central Asia to the Mediterranean and other parts of the world, and then became the main textile material in Asia and Europe. Wool fiber is soft and elastic, and can be used to make woolen cloth, woolen yarn, blankets, felts and other textiles. Wool products have the characteristics of full hand feeling, good warmth retention and comfortable wearing. Sheep wool yarn accounts for a considerable proportion of textile raw materials. Australia, the former Soviet Union, New Zealand, Argentina, and China have the largest sheep wool production in the world. According to fineness and length, sheep wool is divided into five categories: fine wool, semi-fine wool, long wool, hybrid wool, and coarse wool. Chinese sheep wool varieties include Mongolian wool, Tibetan wool and Kazakh wool. The main factors for evaluating wool quality are fineness, curl, color, strength, and weed content.
- The advantages of wool yarn 2. The difference between wool and cashmere 3. The main producing area 4. The structure of wool 5. The type of wool 6. Wool yarn dyeing 7. The chemical properties 8. The processing procedure 9. The surface treatment method of the wool fiber 10. The judgment method
Advantages of wool yarn
Wool yarn is an important raw material for the textile industry. It has the advantages of good elasticity, strong moisture absorption, and good warmth retention. However, due to the high price, it is not used much for the production of non-woven fabrics. Non-woven fabrics produced with good wool yarns are limited to a few high-grade industrial fabrics such as needle-punched blankets and high-grade needle-punched felts. Generally, short hairs and coarse hairs in wool yarn processing are used to produce carpet supporting fabrics, needle-punched carpet sandwich layers, thermal insulation materials and other products through needle punching and stitching. This type of wool has different lengths, high impurities, poor spinnability, and difficult processing. The products can be chemically post-treated to improve quality. Wool textiles are known for their luxurious, elegant and comfortable natural style, especially cashmere has the reputation of "soft gold".
The difference between wool and cashmere
What comes from sheep is called wool, not velvet, of course it can also be called fine wool.
Only cashmere from goats is called cashmere, which is cashmere, cashmere. Cashmere is a thin layer of fine velvet that grows on the outer skin of goats and hides the roots of the goat's coarse hair. It grows in the cold winter to resist wind and cold, and falls off after the spring turns warmer. It naturally adapts to the climate. It is a rare special animal fiber.
1. The scales of wool are arranged tighter and thicker than cashmere, and its milling property is greater than that of cashmere. The outer surface of cashmere fiber is small and smooth, and there is an air layer in the middle of the fiber, so it is light in weight and feels smooth and waxy.
2. The crimp degree of wool is lower than that of cashmere, and the crimp number, crimp rate and crimp recovery rate of cashmere fiber are larger. It is suitable for processing into knitwear with full hand feeling, softness and good elasticity. It is comfortable and natural to wear. Good reduction properties, especially in terms of non-shrinkage after washing, good shape retention, etc. Because cashmere has high natural crimp, it is tightly arranged in spinning and weaving, and has good cohesion, so it has good warmth retention, which is 1.5 to 2 times that of wool.
3. The leather content of cashmere is higher than that of wool, and the rigidity of cashmere fiber is better than that of wool, that is, cashmere is softer than wool.
4. The unevenness of fineness of cashmere is smaller than that of wool, and the appearance quality of its products is better than that of wool.
5. The fineness of cashmere fiber is uniform, its density is smaller than that of wool, and the cross section is mostly regular circular, and its products are lighter and thinner than wool products.
6. Cashmere has better moisture absorption than wool, can fully absorb dyes, and is not easy to fade. The moisture regain is high and the resistance value is relatively large.
7. Wool has better acid and alkali resistance than cashmere, and is less damaged than cashmere when it encounters oxidants and reducing agents.
8. Generally, the pilling resistance of wool products is better than that of cashmere products, but the felting shrinkage is greater.
The advantage of world wool production is in the southern hemisphere.
Oceania's raw wool production accounts for about 40% of the world's total raw wool. Australia mainly produces fine wool, and New Zealand mainly produces semi-fine wool. The annual average individual wool production is more than 5.0 kilograms. The wool production level in South America is also relatively high. Australia, New Zealand, the Soviet Union and China are the main wool producing countries, and their output accounts for about 60% of the world's wool production. In addition to Australia and New Zealand, the main wool exporting countries include Argentina, Uruguay, and South Africa.
The main domestic wool producing areas are the Inner Mongolia Autonomous Region. The softness of the wool produced in the northeast due to the better climate is suitable for the textile industry.
Organizational structure of wool
Wool is a slender solid cylinder with a curled shape. The fiber structure is divided into three layers, namely the scale layer, the cortex layer and the medulla layer.
Scale layer: The scale layer is the surface layer of wool. It grows in a certain direction, from the root to the tip of the hair. Each scale is connected to the cortex at one end of the hair root, and the other end is stretched outwards, covering and connecting. The coverage density of scales on wool varies greatly due to wool varieties. The thinner the wool, the more scales, the longer the overlapped part, and the scales are mostly ring-shaped. The thicker the wool, the fewer scales, and the shorter the length of overlapping coverage. The scales are mostly corrugated and fish-scale, overlapping each other. Since the scale layer stretches outwards and protrudes, if the friction between the fibers is increased, they will be restrained each other to produce a felting effect, and the cohesive force will be strengthened under humid and hot conditions. The scale layer can also give the wool a good luster. The scaly structure is tough, so that the wool has anti-wear and anti-pollution properties.
Cortex: The cortex is the main component of wool fibers. It is composed of many protein cells, and its composition is called keratin or keratin. The cells adhere to each other, and there are gaps in between. The cortex layer is the main part that determines the physical, mechanical and chemical properties of wool fibers. It is divided into two types: orthocortex and paracortex. In the curled wool fiber, it can be straightened and extended up to about 20% after being stressed. After being relaxed, the original curled state can be restored. The ones on the outer side of the curly wave are called orthocortical cells, and the ones on the inner side are called paracortical cells. The orthocortical layer has lower sulfur content than the paracortical layer, so it is chemically more active and easy to stain. The opposite is true for the paracortical layer. In fine wool of fine varieties, two kinds of cortical cells are gathered on the two halves of the hair shaft and entangle with each other along the fiber axis, which is called bilateral isomerism.
Medulla layer: The medulla layer is an opaque loose substance in the central part of the wool fiber. Generally, fine wool has no medullary layer, while thicker wool has different degrees of medullary layer. The more medulla, the straighter and harder the wool shape, and the worse the quality. Wool with a large amount of medulla layer is brittle and fragile, with less curling, and shriveled wool is called dead hair. Some wool has discontinuous hair pulp, and a fiber has the characteristics of fine hair and coarse hair at the same time. Such wool is called two-type wool.
Wool has different classification methods and names.
①According to histological structure:
Hair fibers can be divided into two types: medullated hair and non-medullated hair. The medullated hair is composed of three layers of cells of scale, cortex and medulla; the unmedullated hair has no medulla. The scale layer has a protective effect, and its shape and arrangement can affect the ability of wool to absorb moisture, felt and reflect light. The cortex layer is connected under the scale layer and is related to the strength, elongation and elasticity of the wool fiber. The thinner the wool, the larger the proportion. The medulla layer is the main feature of medullary hairs. It is located in the central part of the hairs. It is composed of polygonal cells with loose structure and full of air. It is easy to distinguish the degree of development by observing the cross-section under a microscope. The more developed the medulla layer, the thicker the fiber diameter and the lower the technological value.
②According to the growth characteristics, tissue structure and process characteristics of wool fiber:
It can be divided into fluff, hair, two-type hair, bristle hair and dog hair. The bristle hairs are short hairs that grow on the face and the lower extremities, and have no technological value. Dog hairs are coarser hairs formed by the primary hair follicles in the early embryonic development of fine-haired lambs, which are gradually replaced by non-medullary hairs during lactation. Therefore, there are only 3 basic types of woolen hair, hairy hair, and two-type hair that can be used as raw materials for wool spinning. The fluff is distributed in the bottom layer of the shag wool quilt. The fine wool quilt is composed of fluff, the fiber is fine and uniform, the average diameter is no more than 25 microns, and the length is 5-10 cm. It is soft and curved, with good elasticity and soft luster. Hair, or coarse hair, is divided into three types: normal hair, dry hair and dead hair, forming the outer layer of the shag wool quilt. Normal hair has a fineness of 40 to 120 microns, with less bending and lack of flexibility. The medulla layer of fine hair is relatively underdeveloped, the cortex layer is relatively thick, the fibers are elastic, and the craftsmanship value is higher. The tissue structure of dry hair is the same as that of normal hair, but the tip is dry and lacks luster. The medulla layer of dead hair is particularly developed, the hair is thick and hard, fragile and fragile. The two-type hair is also called the middle-type hair, and its fineness and other technological values are between the fluff and the hair.
③According to the fiber composition of the quilt:
Can be divided into the same type of hair and mixed hair. The former includes fine wool, semi-fine wool and high-generation modified wool, and their fiber fineness, length, and other appearance characteristics are basically the same; the latter includes coarse wool and low-generation modified wool. The length is inconsistent, the textile value is low, and it is mainly used as raw material for blankets, carpets and felt products.
The structure of the world's wool varieties is roughly 31.3% fine wool, 42.3% semi-fine wool and hybrid wool, and 26.4% carpet wool. The original Chinese sheep breeds are Mongolian sheep, Tibetan sheep and Kazakh sheep. The wool produced is of rough quality and is a mixed type wool, which is mainly used for carpet wool. Among them, Mongolian wool has both cold wool with a fineness of 52 to 58 and coarse wool. Tibetan wool is relatively long, has two types of wool in the strands, has good elasticity and luster, and is the best quality of mixed wool; Xining wool, produced in Qinghai, is a good raw material for bed blankets and carpets. Kazakh wool quilt is often mixed with colored wool such as yellow and brown, and the hair strands contain more dry and dead hair. After the 1950s, China introduced fine-wool sheep and semi-fine-wool sheep from abroad, and successively bred Xinjiang fine-wool sheep and Northeast fine-wool sheep, which improved the quality of wool.
Wool yarn dyeing
It is feasible to use low-temperature auxiliaries miralan LTD and CTC-435 to dye wool at low temperature. Low-temperature dyeing at 80°C can reach the level of conventional boiling dyeing. The optimal dosage of the two auxiliaries is 2%.
The main component of
wool is keratin, which is composed of a variety of α-amino acid residues, which can be linked into a spiral-shaped long-chain molecule, which contains carboxyl, amine and hydroxyl groups, etc., forming salts between the molecules Bond and hydrogen bond, etc. The long chains are connected by cross bonds formed by the disulfide bonds of cystine. The above chemical structure determines the characteristics of wool. For example, when the long chain of wool fiber macromolecules is stretched by an external force, it transitions from α-type spiral to β-type stretched type, and then returns to α-type after the external force is relieved, the appearance of wool is characterized by excellent elongation and elasticity of wool. The strong moisture absorption capacity of wool is related to some groups on the side chain. Wool is more acid-resistant but not alkali-resistant, because alkali easily decomposes the disulfide group in cystine of wool, which damages the hair quality. Oxidants can also destroy disulfide groups and damage wool.
The physical properties of wool mainly include fineness, length, bending, strength and elongation, elasticity, felting, moisture absorption, color and gloss.
Fineness is an important process characteristic to determine the quality and use value of wool fiber. It is expressed by fiber diameter micrometer or quality count; the smaller the fineness, the higher the count, and the finer the yarn will be spun. Length includes natural length and straight length. The former refers to the straight-line distance between the ends of the hair bundle, and the latter is the length measured by straightening the fiber. The elongation of the fine hair is above 20%, and the semi-fine hair is about 10-20%. 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 evaluating the quality of wool. For wool with a neatly bent shape, the spun yarn and products have a soft feel, good elasticity and warmth retention. The fine hairs have a large number of bends and have a high density, and the coarse hairs are wavy or flat without bends. Strength and elongation have a direct effect on the firmness of the finished product. Strength refers to the stress of wool to break; elongation refers to the length increased due to the effect of 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, the thicker the hair, the greater the strength. The more developed the medulla with medullary hair is, the worse its resistance to breaking. The elongation of wool is generally up to 20-50%. Elasticity can keep the original style of products, which is an indispensable feature of carpets and blankets. The felting and hygroscopicity of wool are generally good. Luster is often related to the state of scale coverage on the surface of the fiber. The fine hairs have a weaker ability to reflect light and have a softer luster; the coarse hairs have a strong and shiny luster. Weak luster is often caused by damage to the scale layer.
The raw wool needs to be initially processed into scoured wool before spinning. During processing, the wool is selected to make the quality of the wool more uniform, and then the wool is fluffy by opening the wool to improve the washing effect. Then the wool is washed to make the lanolin form a stable emulsion, and the dirty impurities float in the washing solution. After treatment, wet wool with about 40% water content can be obtained, which is then dried. In production, the combined machine is used to continuously operate once to obtain clean wool, and then enter the top manufacturing process; the top is drafted on the spinning frame and then enters the spinning process.
Wool fiber surface treatment method
Wool surface treatment technology treats wool through physical, chemical, biological and other methods to reduce the degree of felt shrinkage. The degree of felting of the treated wool fiber has decreased.” At present, there are many wool fiber surface treatment technologies, and each method has its own advantages and disadvantages.
current biotechnology treatment of wool fiber is mainly biological enzyme treatment technology. Bioenzyme Because of its specificity and high efficiency, it is favored by the textile industry. However, biological enzymes are still in their infancy in the treatment of wool fibers, and the effect of enzyme preparations is not satisfactory. The specific treatment effects have significant effects and environmental adaptability. Better bio-enzyme products with stable ingredients have become a top priority. Zhu Huajun and others have studied the effects of dichloroisocyanurate, protease, and MTG enzyme treatments on the strength, alkali solubility and friction factor of wool fibers. The research results show that: the first 2 The treatments of these reagents will damage the wool fiber production, cause the fiber breaking strength to decrease, the surface friction factor becomes smaller, and the alkali solubility increases; the fiber after the treatment is processed with MTG enzyme and has a little strength recovery. But as a blank control (Untreated) samples are weakly repaired after treatment; with the increase of the amount of MTG enzyme and treatment time, the reinforcing effect of the enzyme and the slight difference of the fiber surface will first strengthen and then weaken.
Physical methods and
physical measures to process wool fibers Methods include plasma treatment technology, wool stretching and thinning technology, etc. Plasma is an ionized gas-like substance composed of positive and negative ions generated after some of the electrons are deprived of atoms and ionization of atomic groups. The plasma contains energy. After the particles impact on the surface of the material, the energy disappears and the surface of the material is modified. The energy exchange between plasma and material mainly relies on radiation and particle collision. Low-temperature plasma technology is a technology that only uses plasma as the exciter and fiber as the treatment The processing method of the object does not leave waste products in the process, and the reaction that occurs only stays on the surface of the fiber, which not only does not affect the properties of the fiber itself, but also gives the fiber surface new characteristics. Released during the reaction process The energy is huge, so that the goal that the traditional chemical method cannot accomplish can be achieved at a lower temperature. At the same time, this method also has some shortcomings: there are many factors to set the reaction conditions of the experiment, and the processing equipment The reaction process is more complicated, and some technical problems on the processing equipment need to be further adjusted and improved, and it is impossible to realize the enterprise production. Therefore, it only stays in the laboratory stage. After plasma treatment, the wool fabric is wetted. Wetness, breaking strength, and color yield are all improved.
Wool yarn stretching and thinning technology
Wool yarn stretching and thinning technology is a technology that is harmless to the human body and nature. The operation process of this technology is simply summarized as : The specific target chemical bond of the fiber is broken by chemical reagents; the product after chemical pretreatment is stretched by physical methods to straighten the molecular chain and permanently fix it by damp heat. At present, there are 3 ways of stretching and thinning wool fibers. : Untwisted short-gauge holding stretch (holding stretch), false-twisted large-span holding stretch (twisted stretch), and true twist short-gauge holding stretch (composite stretch). After treatment, the surface scale structure of the fiber is destroyed, and the fiber becomes more flexible; the ratio of length and strength Ordinary wool fiber has been improved, and the fiber rigidity is lower than that of ordinary wool. It can be used to develop high-count light-weight fabrics. In the 1980s, the Australian Federal Institute of Industrial Sciences began to explore the possibility of studying wool yarn thinning, which created a precedent for this technology. After that, researchers from all over the world have carried out long-term and in-depth research in this field. Although the stretched and refined wool yarn has the characteristics that ordinary wool does not have, there are some production technical problems: the length is scattered, the main body is small, and some wool yarns dye fast after stretching, which is easy to dye The cylinder is poor, and the color difference between the inner and outer layers of the hair ball also occurs. At present, there are few documents related to the stretching and thinning process.
Chemical methods and
chemical methods to finish wool fibers include nanomaterial modification technology, chemical degradation technology, polymer deposition technology, etc.
Nano material modification technology
When the particle size of the original material is processed to a certain order of magnitude (nano-level), the atomic structure and crystal morphology of the surface have changed, and unique effects different from macroscopic substances have been mutations: surface effects, small size effects, etc. When the number of atoms on the surface of the particle increases, the surface energy becomes larger, which can produce stronger surface effects and chemical activity. The reason for this treatment is that there is no atom that can bind to it, which causes it to become an excited state. The activity of such surface atoms can not only cause changes in the surface structure of nanoparticles, but also cause changes in surface electron spin conformation and electronic energy spectrum. The specific surface area and surface effect produced by nanomaterials can make it have obvious chemical activity and surface adsorption. In the nano-material modification process, the nanoparticles are uniformly distributed in the solvent, and react with part of the free radical groups on the surface scale structure of the wool fiber, so that the nano-powders are permanently aggregated on the wool.
Zhu Yue et al. explored the effect of silver-loaded nano-SiO on the friction and wear properties of ultrafine wool, and formed a nano-thin layer with durable antimicrobial properties on the surface of the wool fiber. Observed by scanning electron microscope, it is found that the ultrafine wool has a certain thickness of antibacterial layer, and the fiber surface becomes smooth. Then, the strength and friction performance of the single fiber before and after the experimental treatment are tested by the testing equipment, and the following results are obtained: The fiber surface is uniform after treatment Improved its anti-fracture performance; the friction performance of the test sample has been greatly improved, the phenomenon of fluffing and pilling has been reduced, and the felt shrinkage of the wool fiber has been weakened. However, there are also some problems in the experiment: the shape of the nanoparticles used is irregular, and the incorporation of the nanoparticles will cause the inverse friction factor of the fiber. Therefore, attention should be paid to the combination of nanoparticles and fibers.
Chemical degradation technology
When wool is processed by oxidants (hydrogen peroxide, gray manganese oxide, sodium dichloroisocyanurate, etc.), specific types of target chemical bonds in keratinocytes are broken, and the number of charged groups or soluble molecules in the stratum corneum increases; hydrophilicity As a result, the scales become soft, resulting in a reduction in the friction factor difference between the forward and reverse scale directions, and the reduction of felting performance. However, this method also has drawbacks, it will damage the fiber cortex layer, thereby affecting the strength of the fiber and other textile functions. Ding Changwang and others selected treatment reagents such as hydrogen peroxide, gray manganese oxide, and sodium dichloroisocyanurate to treat the mutant cashmere fibers. By testing the breaking strength, friction performance, and surface morphology of the four textile fiber samples after treatment, the interference of different types of oxidants on the structure and function of the variable cashmere fiber scales is analyzed, and the effect of hydrogen peroxide is relatively mild. The breaking strength loss is within 5%. The treatment results of potassium permanganate and sodium dichloroisocyanurate are similar, the treatment effect is obvious, and the breaking strength is reduced by about 15%.
Polymer deposition method
Polymer deposition method is a method to reduce friction by depositing high polymer on the fiber scale layer. The principle of anti-felting mainly has 3 methods: ①After adding a small amount of polymer, the fiber scale structure Cross-linking occurs between each other, and cannot cause relative displacement of the fibers; ②After mixing with appropriate treatment materials, the surface of the fiber is formed into a film, and the scales are covered or completely wrapped; ③After adding an excessive amount of treatment, it is wrapped on the fiber The polymer completely isolates it. Most of the reagents or products used in the actual treatment process are solvents that are harmful to the environment or ecology, thereby affecting their application prospects. Aiming at the problem of easy felting and pilling of cashmere and wool products, Zhou Wu used two methods: methacrylamide chemical grafting and M-501 polyurethane treatment to modify the surface of cashmere. The cashmere fiber was analyzed by two surface modification methods. The function of performance is to explore the degree of interference of two kinds of polymer deposition methods on the function of cashmere fabrics. The purpose of the experiment is to determine the performance indicators of cashmere and wool fibers under different mass concentrations.
The development trend of wool fiber surface treatment technology
At present, most of the methods of fiber surface modification treatment are treated with chemical reagents. The treated fiber matrix is damaged, a lot of resources will be wasted during the production process, and it will greatly pollute the environment. How to treat the fiber surface effectively and environmentally has become a current research hotspot. The current domestic research still has the following main problems: ①The selection of reagents for fiber surface modification treatment is still under exploration, and the effects of the reagents used in the same experimental type have not been compared, and more suitable experimental reagents have been selected. ②Different from macroscopic studies, the setting of factors and levels in microscopic experiments will directly affect the changes in the structure of fiber scales, and even damage the dermal layer of the fibers, resulting in instability of fiber friction properties. Therefore, more precise experimental programs need to be studied. In the future development of wool fiber surface treatment technology, when a single technology cannot meet the conditions, researchers should combine different wool fiber treatment technologies. Doing so can not only make up for the shortcomings of each processing technology, but also discover the new characteristics of wool fibers. With the advancement of science and technology, the rapid technological development in the microscopic field will bring new breakthroughs to fiber surface treatment technology.
Sensory identification method
This method does not require any objects or equipment, relying on one's own intuition, long-term work experience, and identification based on the feel of the fabric and suede. The fiber length of rabbit hair is generally 30-50 mm. There are more rabbit hair fibers, which means that the proportion of rabbit ingredients is high and the products are high-end. Acrylic sweaters (commonly known as fake wool sweaters), because acrylic fibers have unique characteristics like wool, it can be difficult to distinguish. But as long as you carefully observe and compare differences, there are still differences. Intuitively speaking, wool products are softer, more elastic, have a large specificity, and have a soft color.
wool products, when burning, smoke and bubbling while burning, accompanied by the smell of scorching hair, a lot of ash, shiny black brittle lump. Acrylic fiber products, when burning, slowly burn while melting, the flame is white, bright and powerful, slightly black smoke, fishy smell, gray in white spherical shape, brittle and fragile. Nylon products burn slowly while melting. There is a little white smoke when burning. The flame is blue with a scent of celery, and it is light brown and hard, not easy to twist.