Introduction of Silicone Resin (II)


2.2.1.2 Synthesis of Methyl Silicone Resin from Methyl Alkoxysilane






The reaction rate of hydrolysis and condensation of methyl alkoxysilane can be controlled by changing reaction conditions. Starting from methyl alkoxysilane, methyl silicone resins with different crosslinking degrees can be synthesized.






Merchandise methylsilane resins with moderate crosslinking degree ([CH3]/[Si] 1.2-1.5) are mostly prepared by hydrolytic condensation of methylalkoxysilane: methyltriethoxysilane and dimethyldiethoxysilane monomers refined by deacidification are mixed with water, and trace hydrochloric acid or appropriate amount of strong acid cation exchange resin (macroporous strength) is added. Acidic ion exchange resin has better catalytic effect. Active clay (dried after acidification) is used as catalyst, heated and hydrolyzed. When the end point is reached, appropriate amount of hexamethyldisiloxane is added to neutralize the catalyst hydrochloric acid, or the ion exchange resin or activated clay used as catalyst is filtered out to terminate the condensation reaction. The product obtained is an alcohol solution of methyl silicone resin.






2.2.2 Methylphenyl Silicone Resin






The main raw materials for industrialized production of methyl phenyl silicone resin are methyl trichlorosilane, dimethyl dichlorosilane, phenyl trichlorosilane and diphenyl dichlorosilane. Some or all of the above monomers are mixed with solvent toluene or xylene in proper proportion, dripped into water under stirring, hydrolyzed at controlled temperature, and treated with water. The by-product HCl (hydrochloric acid aqueous solution) was washed out to obtain hydrolyzed silanol solution, and then some solvents were evaporated to concentrate silanol. Silicon resin was prepared by cold condensation or thermal condensation reaction. Finally, the finished silicone resin was filtered and packaged.






2.2.3 General-purpose methyl phenyl vinyl silicone resin and its related components






The production process of methyl phenyl vinyl silicone resin is similar to that of methyl phenyl silicone resin. Only in addition to methyl chlorosilane and phenyl chlorosilane monomers in hydrolysis raw materials, appropriate amount of methyl vinyl dichlorosilane and other vinyl-containing organosilicon monomers are added. The mixed monomers were hydrolyzed, washed and concentrated to obtain concentrated hydrolyzed silanol, adding metal organic acid salt catalyst, decompressing heat to predefined viscosity, or controlling the condensation reaction end point according to gelation time, and preparing methyl phenyl vinyl silicone resin.






Methylphenyl hydrogenated polysiloxanes used as cross-linking agents in addition reaction of methyl phenyl vinyl silicone resins are usually ring or linear polymers with little degree of polymerization. They are prepared by hydrolytic cyclization of methyl hydrogenated dichlorosilane or by co-hydrolysis of methyl hydrogenated dichlorosilane, phenyl trichlorosilane and trimethylchlorosilane. It's made together.






The active diluents used as additive silicone resins are methyl phenyl vinyl polysiloxane with low viscosity. Their synthesis methods are similar to that of methyl phenyl vinyl silicone resin, which is the main component of additive silicone resins. The difference is that the amount of vinyl side chain monomers and functional monomers (headers) in the raw material ratio is relatively large. A low viscosity polymer with high cross-linking activity was obtained.






2.2.4 Modified Silicone Resin






The production of organic resin blending modified silicone resin is usually in the toluene or xylene solution of methyl phenyl silicone resin, adding alkyd resin, phenolic resin, acrylic resin and other organic resins, fully mixing uniformly to get the finished product.






Copolymerized modified silicone resin is prepared by a series of chemical reactions. Organic resins that can be copolymerized with silicone resin are polyester, epoxy, phenolic, melamine formaldehyde, polyacrylate, etc. There are many synthetic routes for the preparation of copolymerized silicone resin, but the more practical industrial production method is the copolymerization of silicone alcohol and organic resin. That is to say, hydrolysis of methyl chlorosilane and phenyl chlorosilane monomers to obtain hydrolyzed silanol solution or concentrate solution, then adding pre-synthesized organic resin prepolymer to it, then mixing with Co-thermal steam to remove solvent, adding zinc octanoate, zinc naphthalate and other catalysts to conduct co-condensation reaction at 150-170 C until the reaction material reaches. With the appropriate viscosity or predetermined gelation time, cooling, solvent dissolution and filtration, the finished product copolymerized silicone resin is obtained.


From Silicone Innovation Institute