Silicone oil is a polyorganosiloxane of different degree of polymerization chain structure. It is obtained by hydrolysis of dimethyldichlorosilane with water to obtain a polycondensation ring, and the ring body is obtained by cracking and rectifying to obtain a low ring body, and then the ring body, the heading agent and the catalyst are put together to be condensed to obtain each. A mixture of different degrees of polymerization can be obtained by removing low boilers by distillation under reduced pressure.






The most commonly used silicone oil, the organic group is all methyl, called methyl silicone oil. The organic group may also be substituted for a portion of the methyl group with other organic groups to improve the properties of the silicone oil and to suit a variety of different applications. Other common groups are hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl and the like. In recent years, organically modified silicone oils have been rapidly developed, and many organically modified silicone oils with special properties have appeared.






Silicone oils are generally colorless (or light yellow), odorless, non-toxic, non-volatile liquids. Silicone oil is insoluble in water, methanol, glycol and - ethoxyethanol. It is miscible with benzene, dimethyl ether, methyl ethyl ketone, carbon tetrachloride or kerosene. It is slightly soluble in acetone, dioxane, ethanol and alcohol. . It has a small vapor pressure, a high flash point and a flash point, and a low freezing point. As the number of segments n varies, the molecular weight increases and the viscosity increases. Thus, the silicone oil can have various viscosities ranging from 0.65 centistokes to millions of centistokes. If low-viscosity silicone oil is to be produced, acid clay can be used as a catalyst, and telomerization can be carried out at a temperature of 180 ° C, or sulfuric acid can be used as a catalyst, and telomerization can be carried out at a low temperature to produce a high-viscosity silicone oil or a viscous substance which can be made alkaline. catalyst.






Silicone oil is divided into methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl according to chemical structure. Base silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen silicone oil, hydroxyl hydrogen silicone oil, cyanide-containing silicone oil, etc.; from the use, there are damping silicone oil, diffusion pump silicone oil, hydraulic oil, insulating oil, Heat transfer oil, brake oil, etc.






Silicone oil has excellent heat resistance, electrical insulation, weather resistance, hydrophobicity, physiological inertness and small surface tension. In addition, it has a low viscosity temperature coefficient and high compression resistance. Some varieties also have radiation resistance. Performance.






Silicone emulsion




Silicone emulsions are a form of silicone oil. The following is introduced from the aspects of silicone oil fabric soft finishing agent and silicone oil emulsion type defoaming agent.






First, silicone oil fabric soft finishing agent


The silicone emulsion is mainly used as a soft finishing agent for silicone oil fabrics. The first generation of silicone fabric finishes was a mechanical blend of dimethicone and hydrogenated silicone oil (and derivatives thereof). The second generation of silicone fabric finishing agent is a hydroxyl terminated polydimethylsiloxane emulsion, which is prepared by octamethylcyclotetrasiloxane monomer, water, emulsifier, catalyst and other raw materials under certain conditions. Aggregated. Since the polymerization and the emulsification are completed in one step, the invention has the advantages of short man-hour, 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 reactive groups at both ends (hydroxyl groups). It can further react to form a film, which is beneficial to improve the application effect of the emulsion, which is not as good as mechanically emulsified silicone oil.






Hydroxy silicone oil emulsions can be divided into cationic, anionic, nonionic, complex ion and other types of emulsions depending on the surfactant used.






1. Cationic hydroxy silicone oil emulsion


The emulsifiers used in the polymerization of cation-type hydroxy emulsions are generally quaternary ammonium salts (octadecyltrimethylammonium chloride reported in foreign literature), and the catalyst is ammonium hydroxide. Cationic hydroxy emulsion can be used for finishing of various textiles, with improved fabric feel, improved fabric elasticity and smooth and crisp performance. Another unique advantage is that the ideal waterproofing agent for fabrics is combined with methyl hydrogen silicone oil emulsion. , waterproof performance and waterproof durability can reach a very high level, can be used as waterproofing agent for vinylon canopy canvas, waterproofing agent for polyester card.






2. Anionic hydroxy silicone oil emulsion


The anionic hydroxy emulsion is characterized by good compatibility in the fabric finishing agent and the emulsion is very stable. In particular, most of the additives in textile printing and dyeing are anionic. If cationic hydroxy milk is used, it is easy to cause demulsification and bleaching, and anionic hydroxy milk can avoid this drawback, so it is more popular with users and has a wide range of uses.






3. Composite ionic hydroxy silicone oil emulsion


Although cationic hydroxy emulsion is an excellent fabric soft finishing agent, this emulsion is not resistant to hard water and cannot be bathed with dimethylol dihydroxyethylene urea resin (2D) resin, catalyst magnesium chloride and anionic brightener. Used, so there are certain limitations in use. In addition, due to the poor stability of the emulsion, the silicone polymer is easily separated from the emulsion and floated on the liquid surface, commonly known as "bleaching oil". If the cationic and nonionic emulsifiers are used in the emulsion polymerization process, the disadvantages of preparing the hydroxy silicone oil emulsion by the cationic emulsifier can be overcome, and the prepared silicone emulsion can withstand hard water, can be combined with 2D resin, magnesium chloride and The brightener VBL is used in the same bath and has good heat resistance and freeze resistance.






4. Nonionic hydroxy silicone oil emulsion


Non-ionic hydroxy milk is more adaptable and stable than hydroxy-type milk, so many countries have been studying non-ionic hydroxy milk. For example, the new product UltrateX FSA produced by Ciba Cargill is a non-ionic emulsion of hydroxyl-terminated polydimethylsiloxane with a molecular weight of more than 200,000, which is more than the Dc-1111 anionic type of Dow Corning. Hydroxyl milk has taken a step forward.






5. Other reactive group silicone finishing agent


In order to meet the needs of advanced finishing of various types of fabrics, to improve the oil, antistatic and hydrophilic properties of silicone finishing fabrics, and to make chemical fiber fabrics have many advantages of natural fabrics, silicone workers have studied the introduction of other silicone molecules. A reactive group such as an amino group, an amide group, an ester group, a cyano group, a carboxyl group, an epoxy group or the like. The introduction of these groups has a special effect on the silicone fabric finishing agent, for example, the introduction of the silicone molecule into the amino group is suitable for the shrinkage prevention and soft finishing of the wool fabric; the introduction of the amide group is suitable for the antifouling finishing, and the softness is also greatly improved: introduction The cyano group has good oil resistance, and the anti-static effect of the copolymer of polyoxyethylene ether and silicone is good; the organic fluorine-modified silicone has many advantages such as oil repellency, antifouling, antistatic, water repellency and the like.






Second, silicone oil emulsion defoamer


Silicone emulsion type defoamers are generally oil-in-water (O/W) emulsions, ie water is the continuous phase and silicone oil is the discontinuous phase. It is premixed with silicone oil, emulsifier and thickener, then gradually mixed with water, and finally repeatedly ground in a colloid mill until a desired emulsion is obtained.






Silicone oil emulsion defoamer is the most widely used and defoamer in silicone defoamer. It is characterized by easy dispersion in water systems and can be widely used as a defoaming agent for aqueous systems. When used, the emulsion is directly added to the foaming system to obtain a good defoaming effect. In order to improve the defoaming effect and measurement accuracy of the emulsion, it is generally not necessary to directly use more than 10% of the concentrated silicone oil emulsion: instead, it is first diluted with cold water or directly with a foaming liquid to 10% or less. Do not use a liquid that is overheated or too cold to dilute, otherwise it will cause the emulsion to break. The stability of the emulsion will be deteriorated after dilution, and stratification (bleaching) may occur during storage, that is, demulsification. Therefore, the diluted emulsion should be used up as soon as possible. If necessary, a thickener may be added to increase the stability of the emulsion. For batch operation, the silicone oil emulsion can be added one time before the operation of the system, or it can be added in batches; for continuous operation, the silicone oil emulsion should be continuously or intermittently added at the appropriate part of the system.






When using an emulsion type defoamer, special consideration should be given to the temperature and acidity and alkalinity of the foaming system. Because the silicone oil emulsion is more delicate and exceeds its range of use, the emulsion will break prematurely and become inefficient or ineffective. (The amount of the silicone oil emulsion is generally 10 to 10 ppm by weight of the foaming liquid (in terms of silicone oil). Of course, there are also less than 10 ppm and more than 100 ppm in special cases. The optimum amount is mainly determined by experiments.






Most of the silicone oil emulsion type defoamers are oil-in-water type. Depending on the type of silicone oil, silicone oil emulsion defoamers are of the following types:






1. Silicone oil emulsion based on dimethyl silicone oil


This type of defoamer is formulated from dimethyl silicone oil plus emulsifier and water. It can be widely used in fermentation, food, paper, fiber, pharmaceutical, synthetic resin and so on.






2. Silicone oil emulsion based on methyl ethoxy silicone oil


These defoamers are made from methyl ethoxy silicone oil and a compounding agent.






3. Silicone oil emulsion based on ethyl silicone oil


In recent years, silicone defoamers have progressed toward the silicone-polyether block copolymerization (or graft copolymerization). Such defoaming agents have the characteristics of silicone and polyether, so that the defoaming force is greatly improved; the silicone-polyether copolymerized defoaming agent can also be called a self-emulsifying silicone defoaming agent, which is Blocking (or grafting) a hydrophilic oxyethylene chain or an oxyethylene oxypropylene chain in a silicone molecular chain to bond a hydrophobic siloxane moiety with a hydrophilic polyether, such a molecule having a larger The polarity, as a defoaming agent, has a large spreading factor, can be uniformly dispersed in a foaming medium, and has high defoaming efficiency, and is a new type of high-efficiency defoaming agent. This type of self-emulsifying silicone oil which does not require the use of an emulsifier, the defoaming effect is quite satisfactory for some systems, and it is particularly suitable for occasions where it is not suitable to use a general silicone oil emulsion and a general silicone oil emulsion.