Overview of cotton fiber
The fiber covered on the seeds of Malvaceae cotton, also known as cotton, is called cotton for short. It is an important raw material for textile industry. Cotton fiber products have good moisture absorption and breathability, and are soft and warm. Cotton is mostly an annual plant. It is developed from epidermal cells on cotton seeds. The growth of cotton fiber can be divided into three stages: elongation stage, thickening stage and bending stage.
Cotton fiber is the main raw material of China's textile industry and occupies a very important position in textile fibers. China is one of the major cotton producers in the world. At present, China's cotton production has entered the forefront of the world. Cotton cultivation in China is almost all over the country. Among them, the Yellow River basin and the Yangtze River basin are the main areas, plus the five major cotton areas of northwest inland, Liaohe River basin, South China and * * *.
[Edit this paragraph] Cotton fiber type
There are many kinds of cotton, which are mainly classified according to the following two-minute method.
1. Classification by cotton varieties
(1) Fine cotton: also known as upland cotton. The linear density and length of fiber are moderate, generally 25~35mm, the linear density is 2.12 ~1.56 dtex (4,700 ~ 6,400 count), and the strength is 4.5cN. At present, most cotton planted in China belongs to this category.
(2) Long-staple cotton: also known as sea island cotton. The fiber is thin and long, with a general length of over 33mm, a linear density of1.54 ~1.18 dtex (6500 ~ 8500 cm) and a strength of over 4.5cN. Its excellent quality is mainly used for weaving high-quality cotton yarn finer than 10tex. At present, there are few plants in China. In addition to Xinjiang long-staple cotton, the main imports are Egyptian cotton and Sudanese cotton.
There is also coarse cotton with short fiber, which has been eliminated at present.
2. According to the classification of cotton primary processing
Seed cotton is collected from cotton and cannot be directly processed by textile. It must be processed first, that is, the cottonseed in the seed cotton is removed to get lint. The initial processing is also called embossing. After ginning of seed cotton, the percentage of lint weight obtained in the original seed cotton is called lint percentage. The percentage of clothes is generally 30~40%. According to the different primary processing methods, cotton can be divided into serrated cotton and leather roller cotton.
(1) Sawtooth cotton: The lint processed by sawtooth ginning is called sawtooth cotton. Sawtooth cotton contains less impurities, short fiber, neat fiber length and high yield. However, the fiber length is short and the mill has many defects. At present, most fine cotton uses sawtooth ginning.
(2) Roller cotton: The lint processed by roller cotton machine is called roller cotton. Leather roller cotton contains impurities, short fiber, poor fiber length uniformity and low yield. However, the operation of fiber length is small, and the mill has few defects, but there are yellow roots. Lint ginning is suitable for long-staple cotton and low-grade cotton.
[Edit this paragraph] Cotton fiber characteristics
1. Length
The length of cotton fiber refers to the distance between the two ends when the fiber is straightened, which is one of the important physical properties of cotton fiber. The length of cotton fiber is mainly determined by cotton varieties, growth conditions, primary processing and other factors. The length of cotton fiber is closely related to yarn quality and spinning process. Cotton fiber has long length, good uniformity, less short fiber, high yarn strength, uniform evenness, smooth surface and less hairiness.
The length of cotton fiber is uneven. The length and distribution of cotton fiber are generally expressed by main length, mass length, uniformity and short fiber rate. The length of the main body refers to the length of the fiber with the most content in cotton fiber. Mass length refers to the average length of fibers longer than the main body length, which is used to determine the roller gauge during spinning. Short fiber ratio refers to the percentage of fiber weight less than a certain length limit to the total fiber. Generally, when the short fiber ratio exceeds 15%, the yarn strength and evenness will obviously deteriorate. In addition, there are length indicators such as hand-drawn length and span length.
2. Linear density
The linear density of cotton fiber refers to the thickness of fiber, which is one of the important quality indexes of cotton fiber and closely related to the maturity and strength of cotton fiber. The linear density of cotton fiber is also one of the main factors that determine the spinning count and yarn quality, which is related to the handle and luster of the fabric. The finer the fiber, the higher the yarn strength, the better the evenness, and the finer the yarn can be spun.
Step 3: mature
Maturity of cotton fiber refers to the thickening degree of fiber cell wall, that is, the degree of cotton fiber growth and maturity, which is closely related to various physical properties of fiber. Normal mature cotton fiber has thick cross section, high strength, many twists, good elasticity, mercerization, high cohesion between fibers and high yarn strength. Therefore, maturity can be used as a comprehensive index of cotton fiber intrinsic quality.
4. Strength and elasticity
The strength of cotton fiber is one of the necessary conditions for fiber to have spinnability and use value. The higher the fiber strength, the higher the yarn strength. The strength of cotton fiber is usually expressed by breaking strength and breaking length. The strength of fine cotton is 3.5~4.5cN, and the breaking length is 2 1~25km. The strength of long-staple cotton is 4~6cN, and the breaking length is 30km. Because the strength of single cotton fiber is quite different, the fiber strength of cotton bundle is generally measured and then converted into the strength index of single fiber. The elongation at break of cotton fiber is 3%~7%, and its elasticity is poor.
5. Water absorption
Cotton fiber is a porous substance, and there are many hydrophilic genes (-OH) on its cellulose macromolecules, so it has good hygroscopicity. Under general atmospheric conditions, the moisture regain of cotton fiber can reach about 8.5%.
6. Acid and alkali resistance
Cotton fiber has weak resistance to inorganic acids. Cotton fiber is very resistant to alkali, but it will cause lateral swelling. Cotton cloth can be mercerized with dilute lye.
In addition, there are impurities and defects in cotton fiber, such as sediment, leaves and boll shells. And defects such as neps and cables. They not only affect the amount of cotton used in textile, but also affect the processing and yarn quality, so they must be inspected and strictly controlled.
[Edit this paragraph] Characteristics of cotton fabric
Cotton fabric refers to the fabric made of cotton yarn or blended yarn of cotton and cotton chemical fiber. It has the following characteristics:
1. has strong hygroscopicity and large shrinkage, which is about 4~ 10%.
2. Alkali resistance and acid resistance. Cotton cloth is extremely unstable to inorganic acids, and even dilute sulfuric acid will destroy it, but the effect of organic acids is weak and almost non-destructive. Cotton cloth is more resistant to alkali. Generally, dilute alkali has no effect on cotton cloth at room temperature, but under the action of strong alkali, the strength of cotton cloth will decrease. Cotton cloth is often treated with 20% caustic soda solution to obtain mercerized cotton cloth.
3. Light resistance and heat resistance are average. Cotton cloth will slowly oxidize in sunlight and atmosphere, reducing its strength. Long-term high temperature will damage cotton fabric, but it can withstand short-term high temperature treatment in the temperature range of 125~ 150℃.
4. Microorganisms have a destructive effect on cotton fabrics, which is manifested in their intolerance to mold.
5. Hygiene: Cotton fiber is a natural fiber, the main component is cellulose, and there are a few waxy substances, nitrogen-containing substances and pectin. After many tests and practices, the pure cotton fabric has no irritation and negative effects when it comes into contact with the skin, and it is beneficial and harmless to the human body after long-term use, with good sanitary performance.
[Edit this paragraph] Varieties of pure cotton fabrics
Pure cotton fabrics are made of pure cotton yarns. There are many kinds of fabrics and different colors. According to dyeing methods, it can be divided into primary color cotton cloth, dyed cotton cloth, printed cotton cloth and yarn-dyed cotton cloth; According to the fabric structure, it can be divided into plain cloth, twill cloth and forged cloth.
(1) Cotton cloth with natural cotton fiber color without bleaching or printing and dyeing is called raw cotton cloth. According to the yarn count, it can be divided into city cloth, coarse cloth and fine cloth. Their characteristics are: thick cloth body, smooth cloth surface, strong and durable, and large shrinkage rate. Can be used as bed linen, blank accessories or shirt materials.
(2) Poplin Poplin is the main variety of cotton and has a silk style. Its texture is delicate and shiny, the cloth body is soft and smooth, and it is crisp and comfortable to wear, and it is woven in plain weave. The organizational structure of poplin is characterized by that the warp density is about twice as high as the weft density, the exposed area of the warp on the fabric is more than that of the weft, the protruding part of poplin forms obvious diamond-shaped particles on the fabric surface, and the yarn count used is of high quality, so the fabric surface is clear, full of particles, smooth and dense. However, poplin fabric has a great disadvantage, that is, the clothes sewn with it are prone to longitudinal cracks. This is because the density difference between warp and weft of poplin is too large, and the strength between warp and weft is unbalanced, resulting in the strength of warp yarn being nearly twice that of weft yarn.
(3) The grey cloth of wool blue cloth should be singed before dyeing to make the cloth surface smooth and smooth, while wool blue cloth is not. There is no need to singe before dyeing, and there is still a layer of fluff on the fabric after dyeing, so it is called "wool" blue cloth. Wool blue cloth is usually dyed with praseodymium blue dye, which has good dyeing fastness and generous color, and has the feeling of brighter and brighter as it is washed. There are many specifications: wool blue coarse cloth, wool blue fine cloth and so on. Generally suitable for making coats, they are sold everywhere in urban and rural areas.
(4) Plain cloth, bleached cloth and printed cloth are printed, dyed and bleached from all kinds of white grey cloth. According to different colors, it is divided into plain cloth, bleached cloth and printed cloth.
Plain cloth: refers to a single color cotton fabric, which is generally mercerized and piece dyeing.
Bleached cloth: the cotton fabric with white appearance obtained by bleaching the primary color grey cloth can be divided into mercerized cloth and plain cloth. Mercerized cloth has smooth surface, good luster and smooth feel; This light cloth has a dull surface and a rough feel. Bleached cloth is generally used to make underwear, sheets and so on.
Printed cloth: it is made of white grey cloth with low yarn count by printing, and there are two kinds of mercerizing and natural light. According to different printing methods, this kind of cloth has different appearance effects, mostly bright colors on the front and dim on the back. Suitable for women's wear and children's wear.
[Edit this paragraph] Printing and dyeing of cotton fiber
Cotton fiber dyeing formula: reactive dye (high temperature type) x %；; Anhydrous sodium sulfate 50-70A/1; Trisodium phosphate l ~ 2g/ 1.
Operation requirements: add pre-dissolved reactive dyes and auxiliaries into the above-mentioned dyeing bath, adjust the pH to 9, raise the temperature to 70℃ for thermal insulation dyeing for 30 minutes, add sodium carbonate to make the pH to 1 1.5, fix the color for 30 minutes, and carry out cold washing, hot washing, soaping, water washing, dehydration and drying.
Attached:
Dyeing and Finishing Process of Pure Cotton Fabric
The selection of dyeing and finishing process of pure cotton fabric can be divided into scouring and bleaching, dyeing, printing and finishing according to the variety, specification and finished product requirements of the fabric.
1. Both scoured and bleached natural fibers contain impurities, and various sizes, grease and polluted dirt will be added during textile processing. The existence of these impurities not only hinders the smooth progress of dyeing and finishing, but also affects the wearability of fabrics. The purpose of scouring and bleaching is to remove impurities from the fabric by chemical and physical and mechanical actions, so that the fabric is white, soft and breathable, which meets the wearing requirements and provides qualified semi-finished products for dyeing, printing and finishing.
The main processes of scouring and bleaching of pure cotton fabric are: grey cloth preparation, singeing, desizing, scouring, bleaching and mercerizing. 1) Grey cloth preparation: Grey cloth preparation includes grey cloth inspection, cloth turning (batch, packing and printing) and sewing. The purpose of raw cloth inspection is to check the quality of grey cloth and solve problems in time. The inspection contents include physical indicators and appearance defects. The former includes the length, amplitude, weight, warp and weft density and strength of the original cloth, while the latter includes spinning defects, weaving defects, various stains and damages. Usually, about 10% of the total amount is randomly selected. After the original cloth is inspected, it must be divided into batches and boxes, and printed on the cloth head, indicating the variety, processing technology, batch number, box number, release date and code of the cloth turning machine for easy management. In order to ensure continuous batch processing, the original cloth must be stitched.
2) singeing: the purpose of singeing is to burn the fluff on the cloth surface, make the cloth surface smooth and beautiful, and prevent the uneven printing and dyeing defects caused by fluff during printing and dyeing. Fabric singeing means that the fabric quickly passes through a high-temperature flame or rubs a hot metal surface on the open width. At this time, the fluff on the surface of the fabric quickly heats up and burns, while the fabric body is relatively dense and the temperature rises slowly. Before it reaches the ignition point, it leaves the flame or hot metal surface, so as to burn the fluff without operating the fabric.
3) Desizing: In order to weave smoothly, textile mills often size warp yarns to improve strength and wear resistance. The size on grey cloth not only affects the water absorption of fabric, but also affects the quality of dyeing and finishing products and increases the consumption of dyeing chemicals. Therefore, the pulp should be removed before cooking. This process is called desizing. The size on cotton fabric can be removed by alkali desizing, enzyme desizing, acid desizing and oxidant desizing. Alkaline desizing makes the size expand, and the adhesion to the fiber decreases, and it is removed from the fabric after washing. Enzymes, acids and oxidants degrade starch, increase its solubility in water and remove it after washing. Because of the great damage to cotton fiber, acid and oxidant are rarely used alone, and they are often used in combination with enzyme desizing and alkali desizing.
4) scouring: when cotton fiber grows, there are natural impurities (pectin, waxy substances, nitrogen-containing substances, etc. After desizing, most of the size and some natural impurities have been removed, but a small amount of size and most natural impurities remain on the fabric. The existence of these impurities makes the surface of cotton woven fabric yellow and has poor air permeability. At the same time, the existence of cottonseed hull has a great influence on the appearance quality of cotton cloth. Therefore, it is necessary to scour the fabric in high-temperature concentrated alkali solution for a long time to remove residual impurities. Scouring refers to the chemical degradation, emulsification, expansion and other reactions between scouring AIDS such as caustic soda and pectin, waxy substances, nitrogen-containing substances and cottonseed hulls. And impurities are removed from the fabric after washing.
5) Bleaching: The appearance of cotton fabric is not white enough after scouring because there are natural pigments on the fiber, which will affect the brightness of color when used for dyeing or printing. The purpose of bleaching is to remove the pigment and give the fabric the necessary and stable whiteness without obvious damage to the fiber itself. The common bleaching methods of cotton fabric are sodium nitrite method, hydrogen peroxide method and sodium chlorite method. The PH value of sodium hypochlorite bleaching solution is about 10, and it is carried out at room temperature. The equipment is simple, the operation is convenient and the cost is low, but the strength of the fabric is damaged greatly and the whiteness is low. The PH value of hydrogen peroxide bleaching solution is 10. When bleached at high temperature, the bleached fabric has high whiteness and stability, good hand feeling, and can also remove size and natural impurities. Disadvantages are high requirements for equipment and high cost. Under appropriate conditions, desizing, scouring and bleaching can be completed at one time with caustic soda. The PH value of sodium chlorite bleaching solution is 4 ~ 4.5, and it is carried out at high temperature, which has the advantages of good whiteness and little damage to fiber. However, it is easy to produce toxic gas during bleaching, which pollutes the environment and corrodes equipment, and requires special metal materials, so its application is limited. Both sodium hypochlorite and sodium chlorite should be dechlorinated after bleaching to prevent the fabric from being damaged by residual chlorine.
6) Mercerization: Mercerization refers to the process of treating cotton fabric with concentrated caustic soda solution at room temperature or low temperature under the condition of tension in both warp and weft directions to improve fabric properties. After mercerizing, the natural twist in the longitudinal direction of the mercerized cotton fabric disappears due to the bulkiness of the fiber, the cross section is oval, and the reverse direction of light is more regular, thus improving the luster. With the increase of invisible area of fiber, the dye uptake of dye increases. With the improvement of orientation, the strength of the fabric increases, and it also has the function of setting. After mercerizing, the alkali should be fully removed by washing, steaming or washing until the fabric is neutral.
2. Dyeing is a process of combining dyes with fibers physically or chemically, or generating pigments on fibers by chemical methods, so that the whole textile has a certain color. Dyeing is carried out under certain conditions, such as temperature, time, PH value and necessary dyeing auxiliaries. Dyed products should have uniform color and good color fastness. The dyeing methods of fabrics are mainly divided into dip dyeing and pad dyeing. Dip dyeing is a method of dipping the fabric into dye solution to make the dye gradually penetrate the fabric. Suitable for small batch and multi-variety dyeing. Rope dyeing and jigging belong to this category. Pad dyeing is a dyeing method in which the fabric is soaked in dye solution, then the fabric passes through a roller, and the dye solution is evenly rolled into the fabric, and then steamed or hot-melted. It is suitable for dyeing a large number of fabrics.
[Edit this paragraph] Identification of cotton fiber
Recently, some textile and garment manufacturers in the market have not standardized the name and content of fabric components, which has led to unscrupulous merchants taking the opportunity to shoddy and deceive consumers. In order to help consumers accurately identify the main real components of clothing fabrics, a simple identification method is introduced. The simple method to identify the composition of clothing fabric is combustion method. The method is to draw a thread of cloth yarn containing warp and weft from the seam edge of the garment, ignite it with fire, observe the state of the burning flame, smell the smell of the cloth yarn after burning, see the residue after burning, and judge whether it is consistent with the fabric composition marked on the durability label of the garment, so as to distinguish the authenticity of the fabric composition.
Cotton fiber and hemp fiber burn immediately near the flame, burning quickly, with yellow flame and blue smoke. The difference between the smell of burning and the ashes after burning is that cotton burns with paper flavor and marijuana burns with plant ash flavor; After burning, cotton has little powder ash, which is black or gray, while hemp produces a little gray powder ash.
The following is the history of cotton fiber development:
Mexico has a long history of growing cotton. At present, the cottonseed of upland cotton, which accounts for more than 90% of the world's total cotton output, is all originated in Mexico and is the origin center of upland cotton. Mexico is called "the land of cotton". It provides rich and diverse germplasm resources and wild cotton varieties for cotton breeding and improvement in the world, and is known as the natural germplasm base of cotton in the world. It has been confirmed that 9 of the 32 kinds of wild cotton in the world are native to Mexico. Mexico National Cotton Research Center is headquartered in Mexico City. 19 120 wild and semi-wild specimens of cotton seeds were planted in the cotton germplasm resources garden of the institute. In Mexico, since 1980s, the National Agricultural Research Institute has signed a contract with a private farm to establish a research project specializing in color cotton breeding and planting. Great progress has been made in recent years, and colored cotton with different colors, such as reddish brown, khaki and camel, has been cultivated. According to the data, the Uya people and Asidek people in Mexico had planted colored cotton as early as the era. /kloc-When the Spaniards entered southern Mexico and Yucatan Peninsula in the 6th century, the local cotton cultivation was very developed. The islanders turned colored cotton into homespun and made it into the national costume that Mexicans loved to wear, which was very popular in the market.
The history of cotton
Humans have a long history of using cotton. As early as 5000 BC or even 7000 BC, it was used in Central America and has a history of 5000 years in the South Asian subcontinent. At least before 2000, cotton fibers were used as textile raw materials in Guangxi, Yunnan and Xinjiang. At first people didn't realize its economic value. Suleiman, a famous Arab traveler in ancient times, recorded in his Travels of Suleiman that the cotton seen in Beijing today is still regarded as the "flower" in the garden. "Biography of Liang Shu Gaochang" records that "the grass is as real as a cocoon, and the silk in the cocoon is as thin as a row, which is called a white pile." It can be seen that cotton, an important raw material in today's textile industry, was originally regarded as flowers and plants.
There are about three different ways to introduce cotton into China. According to the analysis of flora and historical materials, it is generally believed that cotton spread to the Central Plains from north to south. South Road is the first batch of Asian cotton from India, which was introduced to Hainan Island and Guangdong and Guangxi through Southeast Asia. According to historical records, it was introduced to Fujian, Guangdong, Sichuan and other places at least during the Qin and Han Dynasties. The second route was introduced from India to Yunnan through Myanmar, about the Qin and Han Dynasties. The third way is that African cotton was introduced into Xinjiang and Hexi Corridor through West Asia. During the Northern and Southern Dynasties, the north road was the ancient book "The Story of the Western Regions". During the Song and Yuan Dynasties, cotton spread to vast areas in the Yangtze and Yellow River basins. By the13rd century, cotton from the North Road had spread to the Weishui Basin in Shaanxi Province.
Historical documents and unearthed cultural relics prove that people of all ethnic groups in China's border areas planted and used cotton much earlier than in the Central Plains. Until the Han Dynasty, cotton textiles in the Central Plains were still scarce and precious. During the Tang and Song Dynasties, cotton began to be transplanted to the Central Plains. At present, the earliest cotton textile relic seen in the Central Plains is a cotton blanket found in an ancient tomb in the Southern Song Dynasty. That is, from this period, cotton cloth gradually replaced silk and became the main clothing material of our people. In the early years of the Yuan Dynasty, the government set up a kapok lifting department to collect cotton products from the people on a large scale, with as many as 654.38+10,000 pieces per year. Later, cotton was regarded as the first summer tax (cloth, silk, silk, cotton), which shows that cotton has become the main textile material. After the Yuan Dynasty, the rulers tried their best to collect cotton cloth, published books on cotton planting techniques, and persuaded people to plant cotton. According to Tian Gong Kai Wu in the Ming Dynasty and Song Dynasty, "Every inch of cotton cloth can be obtained" and "there must be ten looms", it can be known that cotton planting and cotton textiles were all over the country at that time.
Due to the poor quality and low yield of African cotton and Asian cotton, China introduced improved varieties of upland cotton from the United States in the late Qing Dynasty. Now, all upland cotton and its varieties are planted in China.
In the 1960s, many countries successively conducted research and experiments on colored cotton. In the 1990s, the United States took the lead in making a breakthrough in the transformation and utilization of wild colored cotton. Colored cotton, that is, naturally grown colored cotton, because of its natural color, does not need China processes such as printing and dyeing, bleaching, etc., which not only avoids the pollution of dyes to water quality and the harm to fabrics, but also reduces the industrial cost. Therefore, colored cotton fabrics have become "green products" and "darling of the future market" and are increasingly favored by consumers. References:
Baidu Encyclopedia, Boss Zou-2007-5-1711:19