<div align="left" style="word-wrap: break-word; color: rgb(68, 68, 68); font-family: "Microsoft Yahei", SimSun, sans-serif; fontGenerally, concentrated silicone oil emulsion with more than 10% concentration is not used directly: instead, it is first diluted with cold water or foaming liquid directly to less than 10% for use. Do not use overheated or overcooled liquids for dilution, otherwise the emulsion will break. The stability of the emulsion will become worse after dilution, and stratification (oil drifting) may also occur during storage, that is, emulsification. Therefore, the diluted lotion should be used up as soon as possible. If necessary, thickeners can be added to improve the stability of the emulsion. For intermittent operation, the silicone oil emulsion can be added all at once before the system is operated, or in batches; for continuous operation, the silicone oil emulsion should be added continuously or intermittently at appropriate parts of the system.
Detailed explanation of silicone oil
Detailed explanation of silicone oil
Silicon oil is a polyorganosiloxane with a chain structure of different degrees of polymerization. It is produced by hydrolyzing dimethyldichlorosilane with water to obtain a primary polycondensation ring body. The ring body is cracked and distilled to obtain a lower ring body. Then the ring body, head-capping agent and catalyst are put together and polymerized to obtain each Silicone oil can be obtained by distilling a mixture of different degrees of polymerization under reduced pressure to remove low boiling matter.
The most commonly used silicone oil, all organic groups are methyl groups, called methyl silicone oil. Organic groups can also use other organic groups to replace part of the methyl groups to improve certain properties of the silicone oil and apply it to various uses. Other common groups include hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl, etc. In recent years, organically modified silicone oil has developed rapidly, and many organically modified silicone oils with special properties have appeared.
Silicon oil is generally a colorless (or light yellow), odorless, non-toxic, non-volatile liquid. Silicone oil is insoluble in water, methanol, glycol and ethoxyethanol, miscible with benzene, dimethyl ether, methyl ethyl ketone, carbon tetrachloride or kerosene, slightly soluble in acetone, dioxane, ethanol and ethanol. . It has a small vapor pressure, high flash point and fire point, and low freezing point. As the number of chain segments n increases, the molecular weight increases and the viscosity also increases. Therefore, silicone oil can have various viscosities, from 0.65 centistokes to millions of centistokes. If you want to prepare low-viscosity silicone oil, you can use acidic clay as a catalyst and telomerize at 180°C, or use sulfuric acid as a catalyst and telomerize at low temperature to produce high-viscosity silicone oil or viscous materials. catalyst.
Silicon oil is divided into methyl silicone oil according to its chemical structure , ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methane Hydroxylic silicone oil, ethyl hydrogenated silicone oil, hydroxyl hydrogenated silicone oil, cyanide-containing silicone oil, etc.; in terms of 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 also has low (high viscosity-temperature coefficient, high compression resistance) and some varieties also have radiation resistance.
Silicone emulsion
Silicone emulsion is a form of silicone oil. The following is an introduction from two aspects: silicone oil fabric softening agent and silicone oil emulsion defoaming agent.
When using emulsion-type defoamer, special consideration should be given to the temperature of the foaming system and conditions such as acidity and alkalinity, because silicone oil emulsions are more delicate than Within its scope of use, the emulsion will break prematurely and become inefficient or ineffective (the dosage of silicone oil emulsion is generally 10 to 10Oppm of the weight of the foaming fluid (based on silicone oil). Of course, under special circumstances, it may be less than 10ppm. and more than 100ppm. The optimal dosage is mainly determined through experiments.
General silicone oil emulsion defoamer is mostly oil-in-water type. Depending on the type of silicone oil, there are several types of silicone oil emulsion defoamer:
1. Silicone oil emulsion based on dimethyl silicone oil
This type of defoaming agent is formulated from dimethyl silicone plus emulsifier and water, and can be widely used in fermentation, food, and papermaking , fiber, pharmaceuticals, synthetic resins, etc.
2. Silicone oil emulsion based on methyl ethoxy silicone oil
This type of defoaming agent is made of methyl ethoxy silicone oil and compounding agents.
3. Silicone oil emulsion based on ethyl silicone oil
In recent years, silicone defoaming agents are developing in the direction of silicone-polyether block copolymerization (or graft copolymerization). This type of defoaming agent has the characteristics of both silicone and polyether, thus greatly improving the defoaming power; the silicone-polyether copolymer defoaming agent can also be called a self-emulsifying silicone defoaming agent. Block (or graft) hydrophilic ethylene oxide chain or oxyethylene oxypropylene chain in the organic silicon molecular chain, so that the hydrophobic siloxane part is combined with the hydrophilic polyether. Such molecules have larger Due to its polarity, as a defoaming agent, it has a large spreading coefficient, can be evenly dispersed in the foaming medium, and has high defoaming efficiency. It is a new type of high-efficiency defoaming agent. The defoaming effect of this type of self-emulsifying silicone oil, which does not require the use of emulsifiers, is quite satisfactory for certain systems. It is especially suitable for situations where it is not suitable to use general silicone oil emulsions and where general silicone oil emulsions are difficult to handle.
�� Larger polarity, as a defoaming agent, has a large spreading coefficient, can be evenly dispersed in the foaming medium, and has high defoaming efficiency. It is a new type of high-efficiency defoaming agent. The defoaming effect of this type of self-emulsifying silicone oil, which does not require the use of emulsifiers, is quite satisfactory for certain systems. It is especially suitable for situations where it is not suitable to use general silicone oil emulsions and where general silicone oil emulsions are difficult to handle.
