Silicone oil is a commonly used lubricant and finishing agent in textile manufacturing, but improper use can cause unsightly silicone stains on fabrics. These shiny oily spots will damage the appearance and quality of textiles. So how to effectively remove and prevent silicone oil stains?

1. How to deal with silicone spots on the surface of fabrics after finalization?

For pure cotton and polyester-cotton fabrics, degreasers and soda ash are generally used to remove them (using degreasers and treating them under alkaline conditions of 80-90 degrees). Silicone removers and soda ash can also be used to remove silicone spots on fabrics. After removal, the color of the fabric becomes lighter and the fabric needs to be re-dyed. Silicone spots on polyester fabrics are relatively simple and generally do not require the re-dyeing step.

2. Amino silicone oil emulsion and fixing agent, soft oil, etc. will sometimes appear silicon spot phenomenon when used at the same time, why not when used alone.

Amino silicone oil is incompatible with additives such as color fixatives and softening oils, causing silicone oil to float.

Amino silicone oil emulsion is a cationic surfactant (or weak cationic), and many chemicals used in the dyeing process are anionic surfactants, such as dyes (some dyes are anionic), leveling agents, diffusants, fixing agents, etc.

After dyeing and finishing, before softening, if these chemicals are not washed thoroughly, when the cationic amino silicone oil series softener reacts with the anionic substances in the dye bath, the amino silicone oil cationic emulsion will be demulsified and the bleaching oil will have soft spots (silicon spots).

The effective way is to strengthen the full washing before softening, and it is best not to soften in the same dyeing machine. After dyeing and washing, pour out the fabric and do softening in the padding car. It can effectively avoid or reduce the formation of soft spots (silicon spots).

3. How to deal with silicon spots produced by woolen sweaters?

In general, manufacturers of silicone oil and softeners will develop matching silicon stripping agents to facilitate the finishing of stickiness or silicon spots during operation, but most of them cannot completely solve the problem and can only reduce it.

In the actual factory operation process, many manufacturers who have successfully solved the problem use gun water (Main chemical composition: dichloroethane, trichlorohexane, etc.) and Jiebao (A color restoration agent) for treatment.

The operation process is as follows:

First, use Dajiewang gun water to soak the problem part for 10-30 minutes. During the soaking process, the gun water is very volatile, so it needs to be sealed as much as possible, and then gently washed. If there is no gun water, you can also use Tianna water instead.

After treatment, there will be slight traces on the problem part, but use Jiebao auxiliary agent for cleaning. After cleaning, the fabric will smell. It needs to be dried with cold air when it is 80% dry. Gloves must be worn during the whole process.

4 Removal of silicone softener on knitted finished fabrics?

Silicone softener can give knitted fabrics a soft, smooth, plump and elastic feel, as well as wrinkle resistance, wear resistance, water washing and good sewing properties, which greatly increases the added value of the product and is therefore favored by customers.

Silicone softeners are chemically stable and have a non-water-soluble macromolecular structure. They have a strong ability to adsorb on the fiber surface, and some of their active groups form chemical bonds with the fiber or self-crosslink, forming a highly polymerized elastic network structure on the fiber surface. Therefore, it is difficult to remove silicone softeners from knitted finished fabrics by ordinary methods.

The re-dyeing and re-repairing rate of knitted fabrics is relatively high. If the silicone softener on the fabric is not removed before re-dyeing or re-repairing, the fabric will not be colored at all. If the removal is not thorough, obvious color fringing will occur. Only after the silicone softener on the reworked fabric is removed can re-dyeing and re-repairing be performed.

After repeated experiments and large-scale production promotion and application, a method for effectively removing silicone softeners from knitted finished fabrics has been explored.

(1) The polyester fiber molecules on all-polyester knitted fabrics do not have polar groups such as hydroxyl groups. The use of strong alkaline caustic soda combined with silicone remover can achieve a level 4 removal effect of silicone softeners on the fabric, and no color fringing will occur during re-dyeing and re-repairing of the fabric.

(2) Cotton knitted fabrics have a large number of hydroxyl groups on cotton fiber molecules. 27.5% hydrogen peroxide, combined with acetone and caustic soda, can be used to destroy the chemical bonds or self-crosslinking between aminosilicone and fiber to achieve the effect of fully emulsifying and dissolving to remove silicone softener.

(3) Polyester/cotton blended knitted fabrics contain both polyester and cotton fiber molecules. The best removal effect is achieved by using acetone AD combined with silicone remover DM-1741.

5. How to use biological enzymes to remove silicone spots on cotton knitted fabrics?

5.1 Causes and treatment processes of silicone spots

Adding some auxiliaries during the pretreatment and dyeing process of cotton knitted fabrics can remove impurities in the fibers and improve the brightness of cotton fabrics, but the fabric feels hard after dyeing. In order to improve the feel and wearability of cotton knitted fabrics, silicone softener is added in the last process. When the fabric is out, many small black spots, namely silicone spots, are found on the surface of the fabric.

From the analysis of molecular structure, the main component of the selected silicone softener is Si-0 and the structure is CH3-0-SiC2H6-Si-(-0-SiC2H6-)n-SiC2H6-Xx, where the alkyl n is above 100. Because the silicone softener molecule is a chain structure, the softener is pumped into the machine after being stirred by a pump. The softener circulates in the dye vat through the pump, breaking the chain structure of the softener molecule, causing silicone demulsification (bleaching oil), sticking to the surface of the fabric, and forming silicon spots. Soap washing and hot washing cannot remove it. After a long period of exploration, we finally used biological enzyme treatment to remove the silicon spots.

5.2 Principle of biological enzyme treatment

(Select appropriate cellulase concentration, temperature, time, machine type, etc.) Using biological enzymes with biological activation, cellulase can hydrolyze the -1,4 glucoside bonds in cellulose fiber molecules into soluble oligosaccharides or glucose in a short time. Due to the large molecular volume of biological enzymes, it is not easy to penetrate into the fiber, so the hydrolysis will only limit the fiber surface, weakening the binding force between the small hairs on the fiber surface and the main fiber. After the solution and the machine operation process, there is also mechanical friction between fabrics and fabrics, and between fabrics and the inner wall of the machine. These silicon spots fall off together with the small hairs on the surface of the fabric, and the silicon spots are removed after washing. In addition, the surface structure of the fabric is clearer, which also plays a role in finishing the fabric.

5.3 Enzyme treatment process

Process flow: Grey cloth enters the pot - hot wash - cold wash - adjust pH value - enzyme treatment - hot wash - dehydration - drying - cloth inspection - calendering

Machine model: rope dyeing machine Q113

Dyeing auxiliaries and process prescription biological enzyme X g/L, buffer l g/L, softener 3l g/L, PH-4.5-5.5 bath ratio 1:20, enzyme treatment temperature 50-53℃, temperature rise 80℃ after 60 minutes, keep warm for 15 minutes; softening; temperature: 30℃*20 minutes.

Source: TEXHR Textile talent network

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