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The lowest shrinkage rate is synthetic fiber and blended textiles, followed by wool, hemp, cotton, silk fabric shrinkage is larger, and the largest is viscose fiber, artificial cotton, artificial wool fabrics. Objectively speaking, cotton fabrics more or less have the problem of shrinking and fading, the key is the finishing behind. Therefore, the general fabric of home textiles is preshrunk. It is worth noting that after pre-shrinkage treatment is not equal to no shrinkage, but refers to shrinkage rate control in the national standard 3%-4% clothing material, especially natural fiber clothing material will shrink. Therefore, in the choose and buy clothing material, in addition to the quality of the fabric, color, pattern selection, shrinkage rate of the fabric should also be understood. 1. Influence of fibers and shrinkage After the fiber itself absorbs water, it will produce a certain degree of swelling. Usually the swelling of fiber is anisotropic (except nylon), that is, the length of shortening, the diameter of the increase. The length difference between the fabric before and after the water and the percentage of its original length is usually called shrinkage. The stronger the water absorption capacity, the more intense the swelling, the higher the shrinkage rate, the worse the dimensional stability of the fabric. The length of the fabric itself is different from the length of the yarn (silk) used, The difference is usually expressed in terms of the shrinkage. Shrinkage ratio (%) =[yarn length - fabric length]/ fabric length After the fabric in water, due to the swelling of the fiber itself, the length of the fabric is further shortened, resulting in shrinkage rate. The shrinkage rate of the fabric is different, the size of the shrinkage rate is different. The fabric fabric structure and weaving tension are different, its shrinkage rate is different. The weaving tension is small, the fabric is tight and thick, the shrinkage rate is large, the shrinkage rate of the fabric is small; Weaving tension is large, the fabric is loose and thin, the shrinkage rate is small, the shrinkage rate of the fabric is large. In the dyeing and finishing process, in order to reduce the shrinkage rate of the fabric, the way of pre-shrinkage finishing is often used to increase the filling density and increase the shrinkage rate in advance, so as to reduce the shrinkage rate of the fabric. 2.The cause of shrinkage 1, fiber during spinning, or yarn in weaving and dyeing and finishing, the fabric of the yarn fiber elongation by external force or deformation, stress in fiber yarn and fabric structure at the same time, in the static dry relaxation state, or static wet relaxation condition, or in a dynamic wet relaxation condition, total relaxation condition, different degree of internal stress release, make the yarn fiber and fabric back to its original state. 2, different fibers and fabrics, the shrinkage degree is different, mainly depends on the characteristics of the fiber - hydrophilic fiber shrinkage degree is larger, such as cotton, hemp, viscose and other fibers; The shrinkage degree of hydrophobic fiber is less, such as synthetic fiber. 3. In the wetting state, the fiber expands under the action of the immersion solution, which makes the fiber diameter larger. For example, on the fabric, the radius of fiber curvature at the interleaving point of the fabric is increased, resulting in the shortening of the fabric length. For example, cotton fiber expands under the action of water, and the cross-sectional area increases by 40~50%, and the length increases by 1~2%, while synthetic fibers shrink by heat, such as boiling water shrinkage, and so on, generally about 5%. 4, textile fiber under the condition of heat, fiber shape and size change and shrinkage, cooling can not return to the initial state, known as fiber thermal shrinkage. The percentage of length before and after thermal shrinkage is called thermal shrinkage rate, generally by boiling water shrinkage test, in 100℃ boiling water, the percentage of fiber length shrinkage as expressed; The percentage of shrinkage can also be measured in hot air above 100 ° C, or in steam above 100 ° C. Fiber performance is also different under different conditions due to internal structure and heating temperature and time. For example, the boiling water shrinkage rate of polyester staple fiber is 1%, the boiling water shrinkage rate of vinylon is 5%, and the hot air shrinkage rate of chloramide is 50%. There is a close relationship between fiber processing and dimensional stability of fabric, which provides some basis for the design of the following process. 3.General fabric shrinkage table Cotton 4% - 10%; Chemical fiber 4% - 8%; Cotton polyester 3.5%- 5%; Color white cloth is 3%; Wool blue cloth is 3-4%; Poplin is 3-4.5%; Floral cloth 3-3.5%; For twill, 4%; Labor cloth is 10%; Rayon is 10%. 4.The reasons affecting shrinkage rate 1. Raw Materials The shrinkage rate varies with the raw material of the fabric. Generally speaking, the fiber with large hygroscopicity, after soaking in water, the fiber expands, the diameter increases, the length shortens, the shrinkage rate is large. If some viscose fiber water absorption rate as high as 13%, and synthetic fiber fabric hygroscopicity is poor, its shrinkage rate is small. 2, density, The shrinkage rate of fabric varies with the density of fabric. If the warp and weft density is similar, the warp and weft shrinkage is also similar. The density of the fabric, the shrinkage will be large, conversely, the weft density is greater than the density of the fabric, the weft shrinkage will be large. 3, yarn thickness The shrinkage rate is also different with the thickness of the yarn. The shrinkage rate of the fabric with thick yarn count is higher, and the shrinkage rate of the fabric with thin yarn count is lower. 4. Production process Fabric production process is different, shrinkage rate is also different. Generally speaking, in the process of weaving and dyeing, the fiber should be stretched many times, the processing time is long, and the shrinkage rate of the fabric with larger tension is large, and vice versa. 5. Fiber composition Natural plant fibers (such as cotton, hemp) and plant regenerative fibers (such as viscose) compared with synthetic fibers (such as polyester, acrylic), easy to hygroscopic expansion, so the shrinkage rate is larger, and wool is due to the fiber surface of the scale structure and easy to felted, affecting its dimensional stability. 6. Fabric structure In general, the dimensional stability of woven fabric is better than knitted fabric. The dimensional stability of high-density fabrics is better than that of low-density fabrics. In woven fabric, the shrinkage rate of plain fabric is less than that of flannel fabric. In knitted fabric, the shrinkage of plain knitted fabric is smaller than that of ribbed fabric. 7. Production and processing process In the process of dyeing, printing and finishing, the fabric will inevitably be stretched by the machine, so there is tension on the fabric. However, the tension of the fabric is easily relieved after being exposed to water, so we may find that the fabric shrinks after washing. In the actual process, we usually use pre-shrinkage to solve this problem. 8. Washing and nursing process Washing care includes washing, drying and ironing. Each of these three steps will affect the shrinkage of the fabric. For example, the dimensional stability of hand-washed samples is better than that of machine-washed samples, and the washing temperature will also affect the dimensional stability. Generally speaking, the higher the temperature, the worse the stability. The drying method of the sample also has a great influence on the shrinkage of the fabric. Commonly used drying methods are, drip drying method, metal mesh tiling method, hanging dry drying method and rotary drying method. Among them, drip drying method has the least effect on the fabric size, while rotary cylinder arch drying method has the greatest effect, and the other two methods are in the middle. In addition, choosing a suitable ironing temperature according to the composition of the fabric can also improve the shrinkage of the fabric. For example, cotton and linen fabrics can be ironed at a high temperature to improve their size reduction. But not the higher the temperature, the better, for synthetic fibers, high temperature ironing can not improve its shrinkage, but will damage its performance, such as fabric hair hard hair brittle.

Classification of fabric According to the manufacturing method is mainly divided into woven cloth and knitted cloth, non-woven fabric new technology. General process of main manufacturing methods 1. Chemical fiber 2. The yarn 3. The weaving 4. The dyeing and finishing 5. Packing woven Two or more sets of yarns are formed at right angles to each other. The yarns appearing longitudinal are called warp, and the yarns going back and forth horizontally are called weft. As woven yarns interlace each other in a vertical manner, they are solid, stable and have relatively low shrinkage. Several common woven fabrics Elastic plain cloth: fabric patterns on the surface and underside, with drawwire added during weaving. As a result of the cloth has a pull wire to make the finished product elastic, more show lines, thinner, smooth surface. Strong and durable, relatively hairy. Because it contains much cotton, it is easy to wrinkle after washing and needs ironing. Apply more to shirts. Yarn-dyed plaid: a variety of color yarn composition, yarn-dyed cloth is not decolorized, color changes. Long twill with more warp than weft, usually 3/1, resulting in a bevel. Special fabric organization, so that the three-dimensional sense of twill is strong, the plain grain is fine and thick, and the luster is soft. Apply to trousers and shirts. Beaded canvas: the surface and the bottom of the cloth grain, the finished product is relatively upright cotton thin beaded sail is easy to wrinkle. Denim: The fabric is the same as twill, but only warp dyed, so that the light color of the cloth can be 10OZ, 13OZ, 14OZ, 15OZ, etc. The variety of the cloth can be applied to different styles of washable, wear-resistant, durable. Relatively hard body. Nylon cloth: The surface and the bottom of the cloth pattern, man-made fiber, durable, easy to wash and dry, cloth surface is hairy, warm. Exposure to sunlight can cause embrittlement. Used for windbreaker or coat fabric corduroy: woven by special loom,it has 3.5 pits, 8 pits, 13 pits, 21 pits and other specifications after hair grabbing treatment. Cloth surface is hairy, warm. More used in shirts, suits, pants material. knitted fabric loop of yarn forms a needle loop, and a new loop passes through the previous loop, and so on, forming a knitted fabric. The process of yarn forming a coil can be advanced either laterally or longitudinally. The transverse knitting is called weft knitting, while the longitudinal knitting is called warp knitting. Introduction to several commonly used knitted fabrics Plain cloth: THE surface is low needle, the bottom is high needle, the weaving method is strong, thinner than double-sided cloth, thinner, breathable, sweat absorption, small elasticity, smooth surface. Easy to wrinkle and deformation, mostly used in T-shirts. Ribbed cloth: cloth grain to form concave and convex effect, more elastic than ordinary knitted cloth, suitable for slim style. Double-sided cloth: the cloth pattern on the surface and the bottom of the cloth is the same, the fabric on the bottom of the cloth is the same, it is smooth than ordinary knitted cloth, rich elasticity and sweat absorption, easy to hair after washing, it is more used for T-shirts. Beaded cloth: The surface of the cloth is porous, like honeycomb. It is more breathable, dry and washable than ordinary knitted cloth. Terry cloth: The bottom surface is like towel loop, 80% cotton +20% polyester fiber, warm, soft, look and feel hot, often used in coats or T-shirts. Hoodie cloth: the bottom surface is like towel loop, cotton yarn weave, the cloth surface is like terry cloth, warm, washable, soft, sweat absorbing, thick. More used for transportation clothing, autumn and winter style. Wafer cloth: cloth surface is wafer shape three-dimensional sense of strong, easy to deformation after washing. Polyester polyester mercerized double-sided cloth: without cotton composition, close-fitting, showing lines, airtight, easy to hook lines. Cloth Flannel cloth: after grabbing hair, cut off the surface of the wool effect, 80% cotton +20% polyester fiber, warm, elastic, machine washable, smooth, soft, static electricity, mostly used for outerwear. printing and dyeing Modern dyeing is mainly according to the fabric varieties, specifications, finished product requirements, etc., can be divided into bleaching, dyeing, printing, finishing and so on. scouring and bleaching All natural fibers contain impurities. In the process of textile processing, various sizes, Oils and contaminated dirt are added. The presence of these impurities not only hinders the smooth dyeing and finishing process, but also affects the wearing performance of the fabric. The purpose of scouring and bleaching is to remove the impurities on the fabric by chemical and physical mechanical action, make the fabric white, soft, and have good permeability to meet the wearing requirements, and provide qualified semi-finished products for dyeing, printing and finishing. The main process of scouring and bleaching of pure cotton fabric 1. Original cloth preparation 2. Singeing 3. The desizing 4. The scouring 5. Bleaching 6. Mercerized 1.The original cloth preparation Raw cloth preparation includes raw cloth inspection, turning, batch, bin, printing, and stitching. The purpose of the original cloth inspection is to check the quality of grey cloth and solve the problems in time. The inspection content includes two items: physical index and appearance defect. The former includes the length, amplitude, weight, warp and weft yarn density and density, strength, etc. The latter such as spinning defects, weaving defects, various stains and breakage. Usually about 10% of the total amount of spot checks. After the inspection of the original cloth, the original cloth must be divided into batches and cartons and printed on the cloth head, indicating the variety, processing technology, batch number, carton number, release date and the code of the person who turned the cloth, so as to facilitate the management. The original cloth must be sewn to ensure continuous batch processing. 2.singeing The purpose of wool firing is to burn the lint on the cloth surface, make the cloth surface smooth and beautiful, and to prevent the presence of lint in dyeing and printing resulting in uneven dyeing and printing defects. Fabric singeing is fabric open-width quickly through high temperature flame or grazed red-hot metal surface, the cloth of wool heat up quickly, and burning, and cloth body is close to heat up slowly, when did not rise to the point of ignition, namely has left the flame or red hot metal surface, so as to achieve to burn to nap, and not the purpose of the operation of fabric. 3.desize In order to smooth weaving, textile mills often size warp yarn to improve strength and wear resistance. The size on the grey cloth affects the water absorption of the fabric, but also affects the quality of dyeing and finishing products, and will increase the consumption of dyeing drugs, so the size should be removed before cooking, this process is called dessizing. The pulp on cotton fabric can be removed from the fabric by alkali desizing, enzyme desizing, acid desizing and oxidizing agent desizing. Alkali desizing makes the paste expand, and the adhesion to the fiber decreases, and is removed from the fabric by washing. Enzymes, acids and oxidants degrade starch, which increases solubility in water and is removed by washing. Because acid, oxidant to cotton fiber damage, rarely used alone, often with enzyme desizing, alkali desizing combined use. 4.boiled-out When cotton fiber grows, there are natural impurities, pectin, waxy material, nitrogenous material, and so on. After desizing cotton fabric, most of the size and some of the natural impurities have been removed, but a small amount of size and most of the natural impurities are still left on the fabric. The presence of these impurities, make cotton cloth cloth surface yellow, poor permeability. At the same time, the appearance quality of cotton cloth is greatly affected by the presence of cottonseed husk. Therefore, it is necessary to boil the fabric in concentrated lye at high temperature for a long time to remove residual impurities. Scouring is to use caustic soda and other scouring additives to chemically degrade pectin, waxy substance, nitrogenous substance, cottonseed shell, emulsification, swelling, etc., to remove impurities from the fabric after washing. 5.bleach After the cotton fabric is boiled, because there are natural pigments on the fiber, its appearance is not white enough for dyeing or printing, which will affect the luster of the color. The purpose of bleaching is to remove the pigment and give the fabric a necessary and stable whiteness without significant damage to the fabric itself. The commonly used bleaching methods of cotton fabrics include sodium hyponitrous acid, hydrogen peroxide and sodium chlorite. Sodium hypochlorite bleaching bleaching solution PH value is about 10, carried out at room temperature, simple equipment, convenient operation, low cost, but the fabric strength damage, low whiteness. The bleach solution PH value of hydrogen peroxide bleaching is 10, bleaching at high temperature, bleaching fabric whiteness is high and stable, feel good, but also can remove pulp and natural impurities. The disadvantage is high equipment requirements, high cost. Under appropriate conditions, combined with caustic soda, desizing, scouring and bleaching can be completed at one time. Sodium chlorite bleaching bleaching solution PH 4-4.5, carried out at high temperature, has the advantages of good whiteness, small damage to the fiber, but bleaching is easy to produce toxic gas, pollution of the environment, corrosion equipment equipment needs special metal materials, so it is limited in the application. Both sodium hypochlorite and sodium chlorite should be dechlorinated after bleaching to prevent the fabric from being damaged by residual chlorine in the presence. 6.mercerization Mercerization refers to the process in which cotton fabrics are treated with a concentrated caustic soda solution to improve the fabric properties under the condition of tension in the longitude and weft directions at room temperature or low temperature. After the mercerization of cotton fabric, the natural longitudinal torsion of the fiber disappears due to the fiber expansion, and the cross section becomes an oval shape. The reverse of light is more regular, thus improving the luster. The increase of the intangibles fixed area of the fiber increases the dyeing rate of the dye. With the increase of orientation, the strength of the fabric is increased and the shape is fixed. After mercerization, it is necessary to remove alkali by means of flushing or steaming box, or washing ground until the fabric is neutral. Dyeing is the process of combining dye and fiber physically or chemically, or producing pigment on fiber by chemical method, so that the whole textile has certain color and luster. dye Dyeing is the process of combining dye and fiber physically or chemically, or producing pigment on fiber by chemical method, so that the whole textile has certain color and luster. The dyeing is carried out under certain conditions such as temperature, time, PH value and required dyeing auxiliaries. Dyeing products should be uniform color, but also need to have good color fastness. The dyeing methods of fabrics are mainly divided into dip dyeing and pad dyeing. Dip-dyeing is a process in which a fabric is dipped in a dye solution and the dye is gradually applied to the fabric. It is suitable for small batch and many varieties of dyeing. Rope dyeing and curly dyeing belong to this category. Pad dyeing is a dyeing method in which the fabric is impregnated in the dyeing liquid, then the fabric is rolled through the roller, the dyeing liquid is evenly rolled into the fabric, and then steam or hot melt is processed. It is suitable for dyeing fabrics in large quantities. printing There are many ways to apply dye or paint to print patterns on fabric, but the main ones are as follows. 1. Direct printing: The method of printing flower patterns of various colors directly on the fabric is called direct printing. In the process of printing, the color paste of various colors will not hinder or destroy the effect. About 80% to 90% of printed fabrics use this method. This method can print white and full flower patterns. 2 Discharge printing, dyed fabric with color can destroy the color of the chemical color printing, this kind of chemical is called discharge agent. Dye resistant to chemicals can also be added to the extraction paddle. In this way, two effects can be obtained, namely, white drawing and color drawing. 3 Anti-dye printing, first printed on the fabric can prevent dye on the anti-dye agent, and then rolled dye, printed on the pattern can prevent the ground color on the dye, this method is anti-dye printing, this method can get three effects, namely, anti-white, color and partial anti-dye. clear up Post-textile finishing technology plays an important role in developing some fabrics with special functions and giving them special functions and effects. With the progress of the technology will continue to appear after finishing the new process, new technology. END

preparation for reading Printing is different from dyeing, so the reactive dyes that are suitable for dyeing are not completely suitable for printing. The dyes that are suitable for printing mainly have the following requirements. First, the requirements for dyes (1) directness is small, affinity is low, diffusion is good Reactive dye printing, due to the immediate drying after printing, there will not be a dyeing balance problem like dyeing, therefore, can be used in the direct, low affinity, good diffusion of dye printing. If use direct reactive dyes, while good for dye uptake, increasing the chance of a reaction with fiber reactive group, but lead to the hydrolysis of dye is not easy to clean from the textile, make water is not white, dust cloth, and poor color fastness, and the greater affinity, contaminates the printing is stronger, easy washing and colour fastness to the poor. If the use of dyes with good diffusible property, it is conducive to the dye transfer from the serosal layer to the fiber and the penetration into the fabric during steaming, and also helps the dye not fixed to be quickly removed from the fabric when washing. (2) the stability of the color paste is better Printing with reactive dye printing ink stability is better, that is, lower reactive dyes when the low temperature reactivity, facilitate mixing and printing, the dye hydrolysis, printed after the high temperature under the action of alkali agent dye can react with fiber to form a covalent bond, therefore, X (procion MX type) in low temperature reactive dyes generally does not apply to printing, with very little, And medium temperature KN type, high temperature K type (Pushian H type), Levafix P, Drimar ene Z and other reactive dyes are more suitable for printing. (3) The dye does not break the bond after printing Reactive dye printing fabric in the storage process should try to avoid acid gas broken bond phenomenon, otherwise it will make color discoloration, color fastness is reduced. Most of the X-type reactive dyes are prone to bond breaking and fade during washing and storage, so they are rarely used in printing. Two, printing dye type (1) single active group reactive dye 1, X type reactive dye ① X type reactive dyes can not be dissolved at a temperature of more than 60℃, and can be dissolved in cold or warm water. ② Because of its high reactivity, the alkali agent used in printing is mostly baking soda NaHCO3, and the dosage should be strictly controlled, and the steam fixation time should be short. ③ Due to the poor stability of the color paste, the dye is easy to hydrolyze, so the alkali agent should be added before the color paste is used. ④ X type reactive dye and fiber generated covalent bond acid resistance stability is poor, so after printing fabric in acid will break the bond fade. Therefore, such reactive dyes are rarely used in the conventional printing process. 2, K type reactive dye ① Dye can be dissolved in hot water above 80℃. ② Due to low reactivity, printing needs to be fixed in a higher alkaline, with baking soda as the alkali printing agent, its dosage is higher than the X type reactive dye. ③ The covalent bond formed with fiber is stable due to the longer steaming time. 3, KN type reactive dye ① The covalent bond of dye and fiber is acid resistant but not alkali resistant, so the dosage of alkali agent should be strictly controlled, and the fabric is not resistant to high temperature alkaline soap washing after printing, which is the biggest characteristic of this kind of dye. ②If the printing is not steamed or post-processed in time after printing, the color of printed fabric becomes light and the "wind imprint" is easy to appear. The main reasons for the wind imprint are: Without timely post-treatment after steaming, the ether bond formed between dye and fiber will be hydrolyzed due to the presence of alkali agent in the color paste, and the hydrolyzed dye will have addition reaction with the dye without reaction, and finally the dye can no longer react with the fiber, so that the color is light. ③If not timely steam, exposed to the air in the cloth color paste in the baking soda may be in contact with SO2 in the air, the formation of sodium bisulfite, under alkaline conditions, NaHSO3 and ethylene sulfone structure of the dye reaction Thus, the dye loses the ability to react with the fiber, which is the main reason for the wind imprint. So the way to prevent the production of air printing is to steam in time after printing, timely post-processing. (2) double reactive dyes 1. M-type reactive dye. ① Due to the double active group in the dye, that is, containing monochloro triazine and ethylene sulfone double active group, and the chance of fiber reaction than K type or KN type increase, so the fixation time is short, the fixation rate is high. ② Because it has both monochloro triazine group and ethylene sulfone group, so the covalent bond formed with fiber acid and alkali resistance stability is better. ③ Although the dye fixation rate is high, but when printing deep color, the floating color is not easy to wash off, ironing is easy to stain color, friction fastness is not good, so it should be strengthened after soap treatment. 2. BPS reactive dye. ① The process has high tolerance, good stability and high fixation rate. ② High improvement rate, bright printing color, good fastness. According to the above requirements, K dyes are ideal reactive dyes in reactive printing. M-type reactive dyes contain two active groups, good reaction performance, high color, suitable for short steam printing process, but dark color dyeing phenomenon is serious. KN type reactive dyes are also suitable for printing, but the color paste is not alkali resistant, can not be cooked in alkaline high temperature soap, easy to occur in the printing process color shallow phenomenon (commonly known as wind printing), so KN type dyes generally use two-phase method or with solid salt FD instead of baking soda to implement printing. Reactive dye color, to use the same type of dye, so that the color of the changeless light caused by color difference, also not because of the dye affinity and spread of different, resulting in printing drying dye shift dyeing inconsistency, uneven pattern block surface phenomenon. To sum up, the reactive dyes selected for printing should have relatively low directness, small affinity, high color fixation rate, high depth lifting force (the so-called depth lifting force refers to the increase of dye concentration in the printing paste, the ability to improve the printing depth), fast diffusion rate, and good washing ability. In addition, it should also have good solubility, color stability and excellent staining.