In textile printing and dyeing auxiliaries, silicone oil is often used for softening. Below we explain some common quality problems of silicone oil, as well as measures to solve the problems.
FAQ
1. Alkaline Problem
When cotton fabrics are pre-treated, a higher concentration of alkali is usually used to remove fabric impurities (especially mercerizing alkali uses a larger amount). The alkali enters the fiber and is not easy to clean. Alkali is also added when dyeing (reactive vat dyes), so the cloth surface may be alkaline during finishing. Chemical fiber fabrics must be restored and cleaned after dyeing. Currently, printing and dyeing factories still use insurance powder and caustic soda for cleaning. If the subsequent cleaning is not clean, it will also cause the soft front fabric to be stained with alkali. Ordinary silicone oil is not resistant to alkali and will break emulsions under alkaline conditions. Therefore, the cloth surface must be washed with an alkali agent before softening to keep the pH in a neutral range.
2. Cohesion problem
On fabrics containing short fibers (cotton, T/R cloth, velvet), some short fibers will inevitably fall off during the processing. The short fibers falling off the cloth will cohesion with ordinary silicone oil and bond with the demulsified silicone oil to form sticky rollers or silicone oil. spot. When the water quality is relatively poor, it will also condense with ordinary silicone oil to produce sticky rollers. In addition, similar situations will also occur with velvet fabrics.
3. The problem of cylinder sticking
When softening, ordinary silicone oil will stick to the cylinder wall Over time, some black oil spots will form on the cylinder wall, which will form silicone oil spots on the cloth.
4. Handfeel problem
As the market has increasingly higher requirements for the handfeel of fabrics, Due to different seasons and different customer requirements, various fabrics need to show a variety of different style requirements, including smooth and drapey, smooth and flexible, fluffy and soft, pure elasticity, etc. A kind of silicone oil can generally only reflect one style.
5. Yellowing problem
Heat yellowing:
Long-term shutdown during operation causes the fabric to remain and turn yellow, and the amino hydrogen of aminosilicone oil is easily oxidized by air to form a chromophore, which causes yellowing. The product turns brown and the brown color makes the white fabric look like it has lost its essential whiteness or has simply turned yellow. The pH is too high and the temperature during drying is too high, causing the cotton fabric to turn yellow.
6. Cost issue
The most confusing issue for printing and dyeing factories at present is the cost issue. The prices of water, electricity and gas are constantly rising, but the printing and dyeing processing fees are not high. As a result, many printing and dyeing factories have been busy for a year but have basically no profits. Therefore, cost control is a problem that printing and dyeing factories need to solve. The cost of finishing auxiliaries is a big part of the printing and dyeing factory, so reducing the cost of finishing auxiliaries is an urgent problem that printing and dyeing factories need to solve.
Causes and treatment methods of silicone oil spots
1. After setting How to deal with silicon spots appearing on the surface of fabrics?
For silicon spots on polyester fabrics, you can use degreasers and soda ash to remove them (use degreasers and treat them under alkaline conditions of 80-90 degrees), or you can Remove with silicone remover and soda ash.
For pure cotton and polyester-cotton fabrics, generally after the silicon spots on the fabric are removed, the color of the fabric becomes lighter, and the fabric needs to be counter-dyed.
2. When amino silicone oil emulsion is used together with color fixing agent, soft oil, etc., silicone spots may sometimes occur. Not when using it, why?
Amino silicone oil is incompatible with color fixing agents, soft oils and other additives, causing the silicone oil to float.
Amino silicone oil emulsion is a cationic surfactant (or weak cation), and many chemicals used in the dyeing process are anionic surfactants, such as: dyes (some dyes are anionic type), leveling agent, spreading agent, fixing agent. . . Once these chemicals are not washed thoroughly after dyeing and finishing and before softening, when the cationic amino silicone oil series softener reacts with the anionic substances in the dye bath, the amino silicone oil cationic emulsion will break and the bleached oil will appear soft. For spots (silicone spots), the effective way is to strengthen sufficient washing before softening and finishing. It is best not to perform softening and finishing in the same dyeing machine. After dyeing and washing, the fabric is poured out and softened in a padding car (special softening tank). It can effectively avoid or reduce the formation of soft spots (silicone spots).
3. How to deal with silicon spots in wool sweaters?
Under normal circumstances, manufacturers of silicone oil and softeners will develop matching silicone stripping agents to facilitate the treatment of sticky or silicone spots during operation, but most of them Partially cannot completely solve the problem, it can only alleviate it.
In the actual factory operation process, many manufacturers that have successfully solved the problem use gun water and Jiebao for treatment.
The operation process is as follows:
First use Dajie Wang gun water to soak the problem part for 10-30 minutes. During the soaking process, the gun water is extremely It is easy to evaporate, so it needs to be sealed as much as possible, and then washed gently. If gun water is not available, Tianna water can be used instead.
After the treatment, there will still be slight traces on the problem parts. However, use Jiebao additives for cleaning. After cleaning, the fabric will smell and needs to be dried until it is 80% dry. When necessary, perform cold air drying. The entire process must be performed with gloves.
4. Silicone on knitted finished fabric Softener removal?
Silicone softeners can give knitted fabrics a soft, smooth, plump and elastic feel, as well as anti-wrinkle resistance, wear resistance, washability and good sewing properties, which greatly improves the performance of knitted fabrics. The added value of the product has been greatly favored by customers.
Silicone softeners are chemically stable and have a water-insoluble macromolecular structure. They have strong ability to adsorb fiber surfaces, and some active groups form chemical bonds or self-crosslink with fibers. An elastic network structure with a high degree of polymerization is formed on the surface of the fiber, so it is difficult to remove the silicone softener on the finished knitted fabric by ordinary methods.
On the other hand, knitted fabrics have a higher rate of counter-dyeing and re-repairing. If the silicone softener on the fabric is not removed and the fabric is re-dyed or re-repaired, the fabric will not be colored at all. , if not removed cleanly, it will cause obvious color stains. Only after the silicone softener on the reworked cloth is removed can it be re-dyed and repaired.
After repeated trials and mass production promotion and application, a method has been found that can effectively remove silicone softeners on finished knitted fabrics.
(1) The polyester fiber molecules on the all-polyester knitted fabric do not have polar groups such as hydroxyl groups. Using strong alkaline caustic soda combined with silicone removal spirit can make the fabric surface organically silicone The softener removal effect reaches level 4, and there will be no color stains on the fabric when it is re-dyed or repaired.
(2) Cotton knitted fabric has a large number of hydroxyl groups on the cotton fiber molecules. Use 27.5% hydrogen peroxide, combined with akesan and caustic soda, to destroy the amino silicon and fiber. Chemical bonding or self-crosslinking can achieve the effect of fully emulsifying and encapsulating silicone softeners.
(3) Polyester/cotton blended knitted fabric contains both polyester and cotton fiber molecules, which can be removed using Akesan AD combined with silicone removal spirit.
5. How to use biological enzymes to remove silicone spots on cotton knitted raw materials?
1. Causes and treatment processes of silicon spots
Add some additives to cotton knitted fabrics during the pre-treatment and dyeing process It can remove impurities in the fiber and improve the brightness of the cotton fabric, but it will feel hard after dyeing. In order to improve the feel and wearing performance of the cotton knitted fabric, silicone softener is added in the last process. When the fabric is released, it is found that there are many spots on the surface of the fabric. Small black spots are silicon spots.
From the molecular structure analysis, the main component of the selected silicone softener is Si-0 and the structure CH3-0-SiC2H6-Si-(-0-SiC2H6-)n-SiC2H6- Xx is an alkyl group and n is 100 or more. Because the silicone softener molecules have a chain structure, the softener-added model is stirred by a pump and then pumped into the machine. The softener circulates in the dye vat through the pump, breaking the chain structure of the softener molecules, causing the silicone to break ( bleach), stick to the surface of the fabric, forming silicon spots.
Soaping and hot washing cannot remove it. After a long period of exploration, we finally chose biological enzyme treatment to remove silicon plaque.
2. Principle of biological enzyme treatment
(Choose appropriate cellulase concentration, temperature , time, machine model,) The use of biological enzymes with bioactive cellulase, its biodegradation effect can hydrolyze the 1.4-glucoside bond in the cellulose fiber molecules into soluble oligomers in a short time Sugar or glucose, due to the large molecular size of biological enzymes, cannot easily penetrate into the fiber. Therefore, hydrolysis will only limit the progress of the fiber surface, weakening the binding force between the small hairs on the fiber surface and the main fiber. Then it passes through the solution and the machine operates. The process is also the mechanical friction between fabric and fabric, and the inner wall of the fabric and the machine. These silicon spots and the small hairs on the surface of the fabric fall off together. After washing with water, the silicon spots are removed. In addition, the surface structure of the fabric is clearer, which also plays a role in smoothing and finishing the fabric.
3. Enzyme treatment process
Process flow: the gray cloth is put into the cylinder, washed once hot and then washed cold One pH adjustment, one enzyme treatment, one hot washing, one dehydration, one drying, one cloth inspection and one calendering
Dyeing material auxiliaries and process prescription biological enzyme Xg/L, buffer lg/L, softener 3lg/L, PH-4.5-5.5 liquor ratio 1:8-12, enzyme treatment temperature 55-60℃, heat up to 8O℃ after 60 minutes, keep warm for 15 minutes; soft; temperature: 40℃*20 point. </p
