In the washing process, in addition to the general shrinkage of the wool fabric, felting occurs. Generally, the dyeing and finishing of wool fabrics, although more loose or less tension equipment, the fabric will still be subjected to more or less tension, thus having a certain degree of dimensional instability, after wetting, it occurs Shrinkage phenomenon. In order to reduce the shrinkage rate of the wool fabric, the drying after the wet finishing and the subsequent dry finishing process should be carefully controlled. When drying, it should be carried out on a needle-clamping machine with an overfeeding device. The warp direction should be properly over-fed, and the width of the door should not be too large. Dry finishing should minimize warp tension, especially in wet and hot conditions, such as steaming and rotary pressing. If the above two aspects are properly matched, the warp and weft shrinkage of the fabric can be maintained within a small range. The condition of wool knitted fabric is similar to that of cotton knitted fabric. Due to the characteristics of co-organized structure, only low tension and loose equipment are used for processing, and the fabric can not be obtained with satisfactory dimensional stability, especially for knitted fabrics with complicated structure. in this way. In order to make the wool knitted fabric have high dimensional stability, it is also necessary to perform a setting process. The commonly used setting methods are autoclave setting and cross-linking agent treatment. The felting problem of the wool fabric has a very important influence on the dimensional stability of the fabric. Therefore, in order to obtain the true dimensional stability of the wool fabric, in addition to taking measures to eliminate the potential shrinkage, it is also necessary to prevent the occurrence of felting. . The reason for felting of wool fabrics is believed to be mainly due to the directional friction effect (DFE) caused by the structure of wool and scaly layers and the elastic characteristics of wool. Therefore, the basic principle of the method for preventing the felting of the wool fabric is based on how to reduce the DFE and change the inherent elasticity of the wool, and it is summarized that the scale layer of the wool is destroyed and the polymer (or resin) is deposited on the surface of the fiber. In these two aspects, the former is called "subtraction" anti-felting treatment, while the latter is called "addition" anti-felting treatment. In addition, a new stable cross-linking between the keratin molecules is established by using a crosslinking agent, and the treated wool becomes less stretchable. Therefore, it has anti-felting properties, but has not yet been widely used in the industry. In the early research work of anti-felting finishing, more emphasis was placed on “subtractionâ€. Recently, the focus of research and development has shifted to “additionâ€. However, from the current production point of view, it is still based on “subtraction†processing. First, "subtraction" anti-felting treatment Among the methods for oxidizing wool, the earliest method is treatment with chlorine, for example, treatment with a cold dilute solution of acidic sodium hypochlorite, which is a relatively simple method, but the treatment process of the method is difficult to control, and uneven treatment often occurs. In the case of drama, it is difficult to dye, and it also has an adverse effect on the performance. Therefore, many improved methods have been further studied, such as controlling the pH of the solution, dissolving the chlorine in an organic solvent, or adding a substance capable of reacting with chlorine and then gradually releasing chlorine in the treatment solution, but the effect is not Too significant or costly, and rarely used. A chlorine release agent which has recently been widely used is = chloroisocyanuric acid or a sodium salt thereof, and a hydrolysis equilibrium reaction occurs in the presence of water. The available chlorine with a lower concentration of HOCI released by hydrolysis reacts slowly with wool, and has the advantages of uniform treatment and no yellowing of wool. The rate of reaction between chlorine and wool can be controlled by pH (generally 4-6) or temperature (generally room temperature ~ 30*(2), and the reaction rate is accelerated with the decrease of pH or the increase of temperature. To make the wool fabric get good. The anti-felting effect, the consumption of available chlorine is about 2-3% (heavy to wool). In addition, the treatment of sodium hypochlorite and potassium permanganate mixed solution is better. Sodium hypochlorite is used in a single application. The pH value is higher than 7, although the oxidation is slow and the treatment is relatively uniform, but when the wool is yellowed and mixed with potassium permanganate, it can be treated in the range of pH=8.5-10, and the wool is not yellowed, but also It has a slightly higher whiteness than the untreated whiteness and feels good. In addition to the above treatment with a solution containing chlorine, there is also a treatment with a chlorine method, that is, treatment with chlorine gas. The chlorine treatment needs to be in a closed container. To carry out, usually firstly adjust the moisture regain of the wool fabric to 8-12% (the moisture regain of the wool under standard conditions is about 18%), then enter the container, pass a certain amount of dry chlorine, and treat it at room temperature for 0? l hours, after the treatment is completed, the pump is used first. There are also many types of chlorine-free oxidizing agents which can be used for anti-felting treatment of wool fabrics, such as hydrogen peroxide, potassium permanganate and other peroxides. Among them, persulfuric acid or a salt thereof is widely used, and the pH of the treatment liquid is generally below 2, and the treatment time varies depending on the temperature and the concentration of the reagent, and the temperature is preferably not more than 50 ° C. In addition, it is treated with a saturated salt solution of potassium permanganate, and the application is also more. The method of oxidizing wool through a corona discharge zone or a low temperature plasma zone has been studied in recent years, but has not yet reached the level of industrial production. The wool anti-felting treatment of wool is processed by fabrics or products, and it is also processed by tops. The processing methods are continuous and intermittent. When processing in the form of tops, it is generally carried out continuously on a rolling stock-washing unit, while Woven Fabrics, knitted garments and fabrics are processed in batches. In order to understand the wool fabric after the above-mentioned chlorine treatment, it will have the anti-felting effect. Some people have observed the wool after the severe wet chlorine treatment, and found that the scale layer on the wool surface was damaged to some extent. And the directional friction effect is much lower, so once the reduction of DFE is considered to be a necessary condition for felting However, when a mild oxidation treatment such as potassium permanganate/salt solution was studied, it was observed by a microscope that the wool scale layer having anti-felting properties was not significantly damaged, and it can be seen from Table 9-4. Out, DFE has not changed, but the cis and reverse friction coefficients have been improved. Therefore, reducing the DFE of the wool fiber is not the only way to obtain the anti-felting property of the wool fabric, and the friction coefficient of the wool fiber is increased, and the fiber is reduced. The possibility of full movement in the product can also achieve an anti-felting effect. Regarding the reason for the change in the friction properties of wool after mild oxidation treatment, in recent years, it has been considered that wool subjected to various oxidation treatments has a common physical property, that is, the scale is wetted than untreated. Soft, like a pocket filled with jelly (mild oxidative treatment) or viscous liquid (more intense oxidation treatment). The softened scale layer is relatively easy to deform. Therefore, when such a fiber is rubbed in the direction of the scaly and reverse scales, since the scale layer is easily deformed, the contact area between the fibers is much larger than that of the untreated fiber, thus causing u. Both U and U. are increased so much that D?F?E? does not change much. Thanks U. Both are increased, so that sufficient one-way movement of the wool in the article is hindered, so that the felt shrinkage is reduced. The increase in wool after relatively severe treatment is small or not increased, or even reduced (when the scale layer is damaged significantly), "so in this case, in addition to p, increase, there is DF?E? The reduction is more detrimental to the felting. In short, there are two ways to change the friction properties of the wool fiber to achieve the anti-felting effect. Increase the friction coefficient or reduce the D?F?E?. After the treated fiber, although the disulfide bond has been partially broken, in the dry state, due to the interaction of hydrogen bonds between molecules, the softening of the scale layer is not easily noticeable. In addition to the above mechanism, another new anti-felting theory has recently been proposed. The theory is based on the idea that untreated wool has an uncharged, hydrophobic surface, so that after the fibers are placed in water or an aqueous solution, there is a tendency to gather together in order to reduce the area in contact with water (meaning Felt shrinking). The anti-feltened fiber after oxidation has a hydrophilic surface and has a relatively high density of charged groups (a SO.H formed by oxidation of a disulfide bond) when the fiber is placed After the water, these fibers are dispersed in the water (meaning anti-felting) due to the electrostatic repulsion between the fibers and the hydrophilic surface of the fibers. This theory is not perfect and is still being studied in depth. Second, "addition" anti-felting treatment The "addition" anti-felting treatment mainly uses the polymer to deposit on the surface of the wool fiber to achieve the anti-felting effect. There have been many types of polymers that have been studied, such as acid colloids of melamine-formaldehyde, silicones, and the like. A similar feature of the recently obtained polymers is that at least part of the polymerization needs to be carried out on the surface of the wool. According to the state of these resins in use, they can be roughly divided into two categories: (1) interfacial polymerization: treatment with monomers to form linear polymers by interfacial polymerization on the surface of wool, deposited on fibers, generally with fibers. Grafting reaction occurs; (2) prepolymer treatment. The prepolymer used usually has three reactive functional groups which are deposited on the surface of the wool by itself or with other crosslinking agents, and polymers which are further polymerized or crosslinked to form a network structure are deposited on the fibers. There are many variations in the processing of wool from monomers or prepolymers, but in essence it depends on the state of the object being treated (such as tops, wool, woven fabrics, knits or garments) and the monomers used or The properties of the prepolymer are selected using a suitable processing technique. Spandex Wp Fabric,Home Textiles Fabric,Pigment Printed Fabric,Spandex Wp Home Textiles Fabric Changxing Dingqiang Textile Co., Ltd. , https://www.dingqiangtextile.com