April 02, 2024

Surfactant is a type of organic compound that contains both hydrophobic and hydrophilic groups. It can be a low molecular weight substance or a polymer. Surfactants can be divided into cationic types according to the type of their hydrophilic groups. Anionic, nonionic and zwitterionic. Silicone surfactants can also be classified in this way. The hydrophobic group of silicone surfactants is composed of alkyl siloxanes that are more hydrophobic than carbon chain types and have a specific Carbon chain have stronger surface activity and have lower surface tension in solutions of the same concentration.

With the expansion of the production scale of silicone monomers and in-depth research on silicone follow-up products, people's understanding of silicone surfactants has further deepened, the varieties of silicone surfactants continue to increase, and the application fields continue to expand. The following is based on organic silicone surfactants. The types of silicone surfactants introduce their application and development in daily chemicals and textiles respectively.

1. Cationic surfactants Amino-modified polysiloxane (referred to as amino silicone oil) and aminosilane are the most typical, largest used, and most widely used organosilicon cationic surfactants. Amino groups include primary, secondary, tertiary and Quaternary ammonium groups. Because amino groups are hydrophilic, amino silicone oil can easily be made into microemulsions. Amino silicone oil emulsions are the most commonly used softeners in textiles; however, amino silicone oils have problems such as yellowing at high temperatures and making the fabrics hydrophobic after finishing. The yellowing problem is mainly solved by changing the type of amino group, such as replacing the primary amino group with cyclohexyl amino group or piperazine group. After replacing it with cyclohexylamino group, the softness is reduced; after replacing it with piperazine group, the softness does not decrease, but the price More expensive. In addition, acid anhydride, alkyl halide, acrylic acid, etc. can also be used to block the primary amino group; according to the author's experiments, epoxy group blocking has the best effect; this can not only improve the yellowing phenomenon, but also improve the slipperiness. The author has trial-produced several Epoxy modifiers have very good effects. There are many ways to improve the hydrophilicity of amino silicone oil: one is to add hydrophilic polyether, carboxylic acid groups, and sulfonic acid groups to the amino silicone oil molecules at the same time; the other is to add hydrophilic polyether, carboxylic acid groups, and sulfonic acid groups to the amino silicone oil molecules; The hydrophilic polyether silane coupling agent is copolymerized with the silicone monomer; the third is to graft the polyether with reactive groups onto the amino silicone oil. Some of these methods are very hydrophilic, but are soft and slippery. Not enough; some are soft and smooth, but not hydrophilic enough. It is difficult to make amino silicone oil not only reduce the softness but also have good hydrophilicity. Dow Corning's DC-8600 is good. The author studied the pro Water amino silicone oil is close to DC-8600 in terms of softness and hydrophilicity, and the price is within 50 yuan/kg.

Low-molecular silane quaternary ammonium salts such as DC-5700 and organosilicon quaternary ammonium salt antibacterial agents developed by many domestic units are all quaternary ammonium salts of trialkoxysilane. These three alkoxy groups are easily hydrolyzed, and the silicone hydroxyl groups generated by hydrolysis It can self-cross-link under alkali catalysis at temperatures above 100°C or combine with the hydroxyl and amide groups on the fiber at higher temperatures to form a washable antibacterial film. This type of antibacterial agent is effective against Gram-positive and negative bacteria. Candida albicans has good antibacterial properties; however, it has poor antibacterial power against certain fungi such as athlete's foot. We add antifungal synergists to the formula to greatly improve its anti-athlete fungus effect, which is especially suitable for treating shoes and socks., making it have the functions of inhibiting foot sweat, removing foot odor, and preventing and treating athlete's foot. Fabrics treated with trialkoxysilane quaternary ammonium salt antibacterial agents have the disadvantage of being hydrophobic. The method to overcome this shortcoming is to add epoxy to the treatment working solution Water-soluble silicone oil. This can not only improve the hydrophilicity of the treated fabric, but also does not affect its washability; the reason is that the epoxy group is highly active and easily combines with the active groups on the fabric. Dialkoxy groups can also be used the method of combining silane quaternary ammonium salt with trialkoxysilane quaternary ammonium salt reduces the number of cross-linking points, increases the quaternary ammonium groups, enhances antibacterial properties, enhances hydrophilicity and antistatic properties; due to moderate cross-linking, the wash resistance does not decrease. many.

Cationic silicone surfactants are mainly used in softening liquid lotions, skin care, hair care and hair care products in the daily chemical industry. When amino silicone oil microemulsion is added to liquid detergents, since the amino silicone oil has a weak positive charge, the fabric has a negative charge. During the washing process, amino silicone oil can automatically adsorb to the fabric. Octadecyltrimethylammonium chloride quaternary ammonium salt softeners tend to flocculate with anionic surfactants and can only be added during the fabric rinsing stage. ; Amino silicone oil microemulsion does not have this problem and can be compatible with anionic surfactants. It is more suitable to use anionic amino silicone microemulsion.

Cationic silicone surfactants, especially quaternized polysiloxanes, are the best conditioners for hair care. Shampoos formulated with polysiloxane quaternary ammonium salts are soft, smooth, antistatic, and easy to use. Combing and other advantages. However, it should be noted that the cation density should not be too high and the dosage should not be too much, otherwise it is easy to cause accumulation. To make a conditioner with excellent comprehensive performance, it is also necessary to combine hydrophilic and antistatic ingredients. It would be more ideal if hydrophilic, antistatic polyether and phosphate ester groups are attached to the siloxane quaternary ammonium salt macromolecules at the same time. The hydrophilic, antistatic polyether and phosphate ester modified polysiloxane developed by our institute Quaternary ammonium salt shampoo conditioners have been put into production; with the continuous improvement and improvement of product quality, the market share will become larger and larger.

Amino silicone oil can also be used as a shampoo conditioner. Transparent shampoo requires that the solubility of the conditioner in the shampoo is quite good. Amino silicone oil with a certain ammonia value can be made into a transparent microemulsion, and with the appropriate anionic surfactant, it can be made into a transparent Shampoo. After many years of experiments, I have found that shampoos made with amino silicone oil conditioners tend to feel astringent after shampooing. The reason for the astringent feel may be that too much amino silicone oil is used and too much is absorbed on the hair; therefore, amino silicone oil is used for When shampooing, the dosage should be reduced and the ammonia level should be lowered.

2. Nonionic surfactants

Nonionic silicone surfactants mainly refer to polyether modified silicone oil. They are mainly used as hydrophilic finishing agents and defoaming agents in the textile industry, such as hydrophilic silicone fabric finishing agents CGF and water-soluble polyether modified silicone oils. Hydrophilic silicone oil defoaming agent. Hydrophilic polyether modified silicone oil is mainly used as hydrophilic skin care and hair conditioner in the daily chemical industry.

An important property of polyether modified silicone oil is that it can vary significantly reduce the surface tension of aqueous or non-aqueous systems; therefore, it has great application prospects in liquid detergents and even in tertiary oil recovery systems. For example: in the formulation of oil stain removal detergents by adding 0.5% to 1% polyether-modified silicone surfactant, the surface tension of the aqueous solution containing 0.2% oil-removing detergent can be reduced to less than 25 mN/m, and the oil-removal effect is reduced. Increased from 61% to 90%.

Another important use of nonionic silicone surfactants is as silicone oil emulsifier. Stable silicone oil emulsion can be made with 1% polyether modified silicone oil.

3. Anionic surfactants

Anionic silicone surfactants include carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type. They can be obtained through the hydrosilylation reaction of the corresponding ester with unsaturated bonds and hydrogen-containing silicone oil, or through the cyclic reaction. Transformation of oxygen-based intermediates. For example, anionic surfactants with carboxyl groups can be produced by hydrosilation reaction between acrylate, α-undecylenate and hydrogen-containing silicone oil; organosilicon phosphate can be modified by polyether silicone oil The hydroxyl group on the molecule is obtained by reacting with phosphorus pentoxide and polyphosphate. Organosilicon sulfonates can be obtained by reacting epoxy-modified silicone oil with sodium bisulfite; the anionic surfactant synthesized by this method reacts with 12 Compared with sodium alkyl sulfate, the surface tension is greatly reduced.

The surface tension of organosilicon sulfonate is much lower than that of sodium lauryl sulfate; if added to the detergent formula, it will greatly reduce the surface tension of water and greatly improve the washing effect.

4. Zwitterionic surfactants

Like non-silicon zwitterionic surfactants, zwitterionic silicone surfactants also include betaine type, amino acid type, imidazoline type, etc. The main characteristics of zwitterionic silicone surfactants are that they are milder and easier to be compatible with, widely used in personal care shampoos. When used in shampoos, it is not irritating to the eyes and skin; the foam is denser and richer, overcoming the foam suppression shortcomings of general silicone conditioners. For example, combining amino silicone oil with binary the zwitterionic surfactant formed by the acid anhydride reaction is used as a hair conditioner. The dry and wet combing grade after hair treatment is improved from grade 4 to 5 in the control sample to grade 1 to 2. The organosilicamide betaine surfactant is used as a shampoo. When used as a conditioner, it is non-irritating to the skin, has good compatibility, and makes the hair combable and shiny.

5. Conclusion

As can be seen from the above introduction, the application prospects of silicone surfactants in daily chemicals and textile industries are bright. In the textile industry, they mainly give textiles softness, smooth feel, antibacterial, mildewproof, antistatic, hydrophilic, waterproof, etc. Special functions; In the daily chemical industry, the ultra-low interfacial tension and non-toxic, mild, soft and smooth properties of silicone surfactants are mainly used for the human body.