Experts Solve Dyeing Problems For Chemical Fiber Dyeing Enterprises

< p > dialogue: Song Xinyuan, Professor of Donghua University, < /p >

< p > Zhang Jie, China, < a href= "http://www.91se91.com/news/index_c.asp" > dye industry < /a > Association professorship < /p >

< p > Wang Mingliang, Daly (China) Co., Ltd., deputy manager of industrial engineering, < /p >

< p > Wang Mingliang: the silk and cotton blended yarn in our company has the problem of deep silk and shallow cotton during the process of dyeing. What is the cause of the problem and how should we solve it? < /p >

< p > Song Xinyuan: the phenomenon of silk depth and shallow cotton in the dyeing process of silk and cotton fabrics is mainly due to the fact that the charge problem is not solved.

Because the dyeing mechanism of pigment dyeing is different from that of dyestuff, the coating is different from the pigment. In the process of synthesis and refinement, the coating must be added with dispersant or active agent to ensure that the coating particles will not appear agglomeration and precipitation in the water.

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< p > because the paint manufacturers do not know what auxiliaries the dyeing and finishing manufacturers need, therefore, the two key factors affecting the performance of coatings are not good enough to handle the polarity and charge of the coating particles.

As far as I know, a target= "_blank" href= "http://www.91se91.com/" > textile > /a > pigment printing has been used in the past. For the sake of safety, non-ionic dispersants are used. Non-ionic dispersants can ensure the uniform dispersion of the paints and will not cause sedimentation. However, during dyeing process, the coloring effect of the cationic modified yarns is very great.

In fact, when the fiber is in water, its surface will be charged with different charges.

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< p > another reason is that the structural composition of silk and < a href= "http://www.91se91.com/news/" > cotton < /a > is also very different. The surface of silk is smooth and smooth, especially after degumming, the surface of silk is more smooth; the surface of cotton is coarser, and there are some longitudinal cracks.

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< p > the color of silk is mainly because the silk is a protein fiber. In the solvent of pH <4.5, the surface of the wire is positively charged; the pH value is not charged at about 4.5; when the pH value is >4.5, it has negative charge, which is also the reason why silk and wool need to be dyed under acidic conditions. Because under acidic conditions, the amino groups of silk and wool are more, the carboxyl group will increase gradually with the increase of pH value. When pH value reaches 4.5, the quantity of amino and carboxyl groups is basically the same, and the positive charge and negative charge neutralize, and the surface of the wire is no longer charged.

At present, the coating particles are mainly negatively charged at pH value <5, and with the decrease of pH value, the negative charge will become more and more.

It can be seen that when the pH value is <4.5, the surface of the wire is positively charged, the coating particles are negatively charged, and the positive charge and the negative charge attract each other. This is the main reason why the silk is dyed deeper.

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< p > so in the dyeing process of silk and cotton, if the pH value is acidic, then the silk attracts more particles and the color is deeper. At the same time, the adhesion of adhesive to silk is stronger than that of cotton, which can explain that after drying, the dyeing of silk is not only deep but also firm.

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< p > although the same is < a href= "http://www.91se91.com" > protein fiber < /a >, because of the influence of surface scales, wool has no silk color and no silk firmness.

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< p > so to achieve uniform dyeing of silk and cotton blended fibers, cationic modification of cotton fibers must be carried out. When the amount of cationic modifier is small, the color of silk will be deeper, and the amount of cationic modifier will increase to a certain extent, and the dyeing effect of silk and cotton will be closer to each other and eventually achieve unity.

Because silk also has many reactions with cationic modifiers, the amount of hydroxyl in silk is less than that in cotton. A small amount of cationic modifier will react with silk first, especially in weakly alkaline conditions. The modifier always reacts with silk first. Only when the amount of cationic modifier is higher, will it react with cotton fiber, and finally achieve cationic modification of cotton fiber.

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< p >, it can be seen that in production, cationic modification of < a href= "http://www.91se91.com" > cotton fiber < /a > must be carried out, so that the surface of cotton fiber is positively charged to achieve uniform dyeing.

Many enterprises are doing, but the problem is concentrated on the lack of modification. The main reason is that the molecular weight of cationic modifier is relatively low, because the number of original negative charges on the fiber surface is very small, and the adsorption ability of the modifier to the fiber is very weak. Therefore, it is necessary to modify the fibers at low temperature. After low temperature plasma modification, the negative charge of the fiber surface will increase obviously, and then the cationic modifier will be modified by cationic modifier. The modification will be permanent. When the dyes are dyed under alkaline conditions, the color of the cotton fiber will obviously become deeper, and the color fastness of dyeing will also increase by half a grade without the adhesive. Actually, cationic modifiers are now available.

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< p > I hope that the coating manufacturers will test the distribution of the potential and the particle size distribution of the coating particles. The latest particle size distribution of the coatings is mainly concentrated at about 0.15 microns, and the color fastness of the coatings is very strong.

Our coatings are mainly used in low-grade, non bright fabrics. The future coatings should be developed in the direction of high-grade, multi components and functional, so as to achieve significant economic and social benefits.

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< p > Wang Mingliang: plasma treatment is restricted by conditions such as vacuum and high pressure.

Can plasma processing be realized in actual production? < /p >

< p > Song Xinyuan: there are many kinds of plasmas. The plasma I speak is atmospheric atmospheric plasma. Strictly speaking, the plasma in physics is different. The conditions of plasma production in physics may need to be produced under the condition of vacuum or inert gas.

My atmospheric atmospheric plasma can dissociate the atmosphere under the atmosphere and produce particles of cations, anions and other ions.

At the same time, special attention should be paid to oxygen when plasma is modified to fiber, because it is difficult to oxidize fibers without oxygen.

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< p > Wang Mingliang: how to judge whether the modification of fiber is adequate after modification? < /p >

< p > Song Xinyuan: mainly depends on the characteristics of the fiber, the first is the hydrophilic property of the fiber surface; the second is the visual condition of the surface of the fiber under the high power microscope; third, the potential of the fiber, the potential and the potential of the fiber, and this test needs more professional equipment, specifically how to determine whether the cationic modification is adequate, and requires professional testing means and instruments.

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< p > Wang Mingliang: why do some products suddenly appear nickel exceeding the standard? How should we prevent them? < /p >

< p > Zhang Jie: nickel is the 16 internationally banned and restricted heavy metal. Occasionally, it is found to be excessive in textiles, so nickel is not the main controlling object now.

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< p > nickel produces two reasons. The first is the "a href=" http://www.91se91.com "> equipment < /a >, especially the stainless steel equipment will contain nickel, during the use of chemical reaction, nickel will appear in the textile; second nickel is often mixed with other heavy metals, if the early dyeing and finishing link is not enough, nickel will also be lost to the textile, so when the product is found to contain nickel, the amount of nickel is generally very small.

In general, the sources of nickel are mainly stainless steel and some inorganic compounds.

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< p > nickel removal is relatively difficult at present. There is no special nickel fixative. However, chromium has special chromium removal fixative. This situation does not appear much. You may try it with chromium fixing agent. If complexation can be achieved, it can solve the problem of excessive nickel.

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