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Methyl phenyl silicone knowledge
Methyl phenyl silicone resin is the mainstream of silicone resin, mainly including electrical insulating varnish, heat resistant coating, glass fiber tube cloth impregnating material, silicone varnish for laminate, silicone molding compound, semiconductor device packaging material, modification Use intermediates and other series. Methyl phenyl silicone resin is also used as a flame retardant additive for organic polymers, imparting flame retardancy to plastic products, and is also used as a heat-sensitive phase change material, such as a normal support component of heat-shrinkable silicone rubber products.
Methyl phenyl silicone synthesized from chlorosilane
1. Methyl phenyl silicone varnish: It is prepared by co-hydrolysis condensation of various methylchlorosilanes and phenylchlorosilanes.
In the first step, a certain proportion of methylchlorosilane and phenylchlorosilane are co-hydrolyzed, the reaction is allowed to stand for separation, the acid water layer is separated, and the low molar mass polysiloxane toluene solution is washed to neutral with water. ,filter. (The low molar mass polysiloxane toluene solution prepared at this time can be used as an intermediate for weathering paint varnish or modified silicone resin)
If there is a laminate or heat-resistant paint varnish, further polycondensation is required. First, a portion of the toluene is distilled off to adjust the mass fraction of the polymer to 50-60%, and then polycondensed to a certain viscosity in the presence of a reflux temperature or a catalyst. The water formed in the polycondensation reaction is taken out by toluene, and care should be taken to prevent gelation during the reaction.
2, solvent-free methyl phenyl silicone resin: solvent-free methyl phenyl silicone resin at room temperature or low softening temperature, mainly used as electrical insulating varnish, heat-resistant coating, semiconductor packaging material and heat-sensitive softening material.
3. The difunctional organochlorosilane and the trifunctional organochlorosilane are separately hydrolyzed and condensed to obtain a block copolymerized methyl phenyl silicone resin. (Methylphenyl silicone varnish prepared by this method, the pre-polymerized silicone resin is a non-viscous solid after solvent evaporation, used as a glass fiber fabric treatment, and the surface is non-stick after air drying, which can improve the lamination process. The laminate has good flexibility. This silicone varnish is used as a high temperature resistant coating and can withstand 1200 ° C. The resin itself does not decompose at 600 ° C, and the metal oxide pigment in the high temperature coating is slowly decomposed above 600 ° C. One).
4. The method of first alcoholysis and then hydrolysis and condensation to prepare methylphenyl silicone resin: the organic chlorosilane is firstly alcoholized without solvent, and then hydrolyzed and condensed to form methylphenyl silicone resin, which can simplify the process. The prepared prepolymer silicone resin can be used as a modified intermediate of an alkyd resin or a polyester resin.
5. Silicone varnish and silicone molding compound for glass cloth
(1) Silicone varnish for glass cloth tube: The glass cloth tube treated with silicone varnish is mainly used for coating and protection of heating and heating parts of household appliances, automobiles, motors, transformers, etc. It is a large demand. Heat resistant electrical insulation material. The silicone varnish for glass cloth is a kind of soft lacquer film which can form a soft lacquer film in a methyl phenyl silicone resin product, and has a high D chain content.
(2) Methylphenyl silicone resin for molding compound: Silicone molding compound is based on methylphenyl prepolymerized silicone resin, with appropriate amount of quartz powder, white carbon black, diatomaceous earth, calcium stearate, etc. A filler, a mixture of thermosetting correction molding or injection molding prepared by kneading. The shaped articles have excellent electrical and electrical insulation properties, high and low temperature properties, and good mechanical properties. It can be used to make arc shields, switchboards, reversing switches and connectors for various electrical appliances and instruments. The methylphenyl silicone resin used has a higher T chain content and an R/Si value of between 1.0 and 1.4.