Knowledge of Silicone Emulsion

Sep 6, 2021

Silicone oil r is CH3, OH; R´, is CH3, H, etc. The oil content is generally 20% to 30%. The pH value is 6～8. Centrifugal stability (3000r/min) 15-30min. The surface tension is small, and the contact angle to water is large. Heat and oxidation resistance. It is prepared by emulsion polymerization of octamethylcyclotetrasiloxane in the presence of anionic surfactants such as sodium dodecyl sulfonate or cationic surfactants such as cetyltrimethylammonium bromide and a catalyst . It is a kind of textile chemical finishing agent with excellent performance. It is often used for soft elastic and smooth finishing of fabrics, silk-like finishing, wool-like finishing, water-repellent and waterproof finishing, etc. It can be used alone or mixed with other finishing agents. The fabrics finished with it can obtain the quality effects of comfort, stylization, high-grade and functionalization.

Product type editing Voice
Silicone fabric softening finishing agent.Silicone emulsion is mainly used as a softening finishing agent for silicone oil fabrics. The first generation of organosilicon fabric finishing agents is a mechanical mixture of dimethyl silicone oil and hydrogen-containing silicone oil (and its derivatives). The second generation of organosilicon fabric finishing agent is hydroxy-terminated polydimethylsiloxane emulsion, which is made of octamethylcyclotetrasiloxane monomer, water, emulsifier, catalyst and other raw materials under certain conditions. Aggregated. Since the polymerization and emulsification are completed in one step, it has the advantages of short working hours, high work efficiency, simple equipment, convenient operation, etc., and the obtained emulsion is very stable, the particles are very uniform, and the prepared polymer has active groups (hydroxyl groups) at both ends. ) It can further react to form a film, which is beneficial to improve the application effect of the emulsion, which is beyond the reach of mechanically emulsified silicone oil.

Hydroxy silicone oil emulsions can be divided into cationic, anionic, nonionic, composite ion and other types of emulsions according to the different surfactants used.
1. Cationic Hydroxy Silicone Oil Emulsion
The emulsifier used in cationic hydroxyemulsion polymerization is generally quaternary ammonium salt (octadecyltrimethylammonium chloride reported in foreign literature), and the catalyst is ammonium hydroxide. Cationic hydroxyemulsion can be used in the finishing of various textiles. It has the properties of improving fabric hand feeling, improving fabric elasticity, smoothness and crispness. Another unique advantage is that it is an ideal waterproofing agent for fabrics. It can be used in combination with methyl hydrogen silicone oil emulsion. , Waterproof performance and waterproof durability can reach a very high level. It can be used as a waterproofing agent for vinylon tent cover canvas and a waterproofing agent for polyester kabu.
2. Anionic Hydroxy Silicone Oil Emulsion
Anionic hydroxyemulsion is characterized by good compatibility in fabric finishing agents, and the emulsion is very stable. In particular, most of the auxiliaries in textile printing and dyeing are anionic. If cationic hydroxyemulsion is used, it is easy to cause demulsification and bleaching oil. Anionic hydroxyemulsion can avoid this disadvantage, so it is more popular with users and has a wide range of uses.
3. Compound ionic hydroxy silicone oil emulsion
Although cationic hydroxyemulsion is an excellent fabric softening and finishing agent, this emulsion is not resistant to hard water and cannot be used in the same bath with dimethylol dihydroxy ethylene urea resin (2D) resin, catalyst magnesium chloride and anionic brightener Use, so there are certain limitations in use. In addition, due to poor emulsion stability, silicone polymers are easily separated from the emulsion and float on the liquid surface, commonly known as "floating oil". If in the emulsion polymerization process, cationic and nonionic emulsifiers are used for compounding, it can overcome the shortcomings of cationic emulsifiers to prepare hydroxy silicone oil emulsion. The brightener VBL is equivalent to bath use, and has good heat resistance and freezing resistance.
4. Non-ionic hydroxy silicone oil emulsion
Non-ionic hydroxyemulsion has stronger adaptability and better stability than free hydroxyemulsion. Therefore, many countries are vigorously researching non-ionic hydroxyemulsion. For example, the new product UltraX FSA produced by Ciba-Geigy, Switzerland, is a non-ionic emulsion of hydroxy-capped polydimethylsiloxane with a molecular weight of more than 200,000, which is better than Dc-1111 anionic hydroxy Breast took a step forward.
5. Organosilicon finishing agent with other active groups
In order to meet the needs of advanced finishing of various types of fabrics, improve the anti-oil, antistatic and hydrophilic properties of silicone-finished fabrics, and make chemical fiber fabrics have many advantages of natural fabrics, silicone workers have studied the introduction of other silicone molecules. Active groups such as amino, amide, ester, cyano, carboxy, epoxy and so on. The introduction of these groups makes organosilicon fabric finishing agents have special effects. For example, the introduction of amino groups of organosilicon molecules is suitable for shrink-proof and soft finishing of woolen fabrics; the introduction of amide groups is suitable for anti-fouling finishing, and the softness is also greatly improved: introduction The cyano group has good oil resistance, and the copolymer of polyoxyethylene ether and silicone has good antistatic effect; organic fluorine modified silicone has many advantages such as oil repellency, antifouling, antistatic, and water repellency.

Silicone oil emulsion type defoamer is the most widely used defoamer and the largest amount among the silicone defoamers. It is characterized by being easily dispersed in water systems and can be widely used as a defoamer in water phase systems. When in use, add the emulsion directly to the foaming system to obtain a good defoaming effect. In order to improve the defoaming effect of the emulsion and the accuracy of measurement, generally do not directly use more than 10% concentrated silicone oil emulsion: instead, first dilute it to less than 10% with cold water or directly with foaming liquid. It is contraindicated to use hot or cold liquid to dilute, otherwise it will cause the emulsion to break. The stability of the emulsion will become poor after dilution, and the phenomenon of layering (oil floating) may also occur during storage, that is, demulsification. Therefore, the diluted emulsion should be used up as soon as possible. If necessary, thickeners can be added to improve the stability of the emulsion. For the batch operation process, the silicone oil emulsion can be added at once before the system is running, or it can be added in batches; for the continuous operation process, the silicone oil emulsion should be added continuously or intermittently at the appropriate part of the system.