Silicone resin is different from silicone oil and silicone rubber. The glass transition temperature (TG) of cured silicone resin is more than 200 ℃, while that of typical silicone rubber is less than - 60 ℃. Methyl silicone resin has the lowest carbon content, high heat resistance, minimum steric hindrance of methyl groups connected to silicon atoms, high crosslinking degree, high hardness and low thermoplastic property. It is ideal as a waterproof and moisture-proof adhesive. However, the compatibility between pure methyl silicone resin and pigment is poor, and the thermal elasticity is small. The introduction of phenyl into polymethylsiloxane can improve the thermal elasticity of the product, the miscibility of pigment, and the adhesion to various substances, and also improve its thermal stability.

The properties of methylphenyl silicone resin mainly depend on two factors: one is R / Si and the other is the ratio of methyl to phenyl (CH 3 / C 6H 5) The type of organic groups connected by silicon atoms has a great influence on the properties of the resin. When it is methyl, it can give the silicone resin thermal stability, demoulding property, hydrophobicity and arc resistance; When it is phenyl, it gives the resin oxidation stability, which can destroy the crystallinity of the polymer in a certain range; When it is vinyl, it can improve the curing characteristics of silicone resin and bring about coupling; The lubricity of the polymer can be improved when it is tetrachlorophenyl; When it is phenylethyl, the miscibility between silicone resin and organic matter can be improved; The results show that the water solubility of the polymer can be improved and the coupling property can be brought about when it is aminopropyl; The hydrophobicity of silicone resin can be improved when it is amyl. Therefore, different organic groups can be introduced into the preparation of silicone resin.   

In order to improve the adhesion of silicone resin, silicone resin can be copolymerized with polyester, epoxy, phenolic, etc. silicone polyester copolymer can be prepared by condensation reaction of polyester containing hydroxyl group with silane (or siloxane) containing alkoxy group, or with silane (or siloxane) containing hydroxyl group.  

There are many ways to synthesize organosilicon epoxy copolymer, but most of them are prepared from commercial epoxy resin by CO condensation reaction with low molecular weight organosilicon resin containing alkoxy or hydroxyl groups according to different requirements. Silicone phenolic copolymer can also be prepared by copolycondensation of soluble silicone resin and phenolic resin, or by copolycondensation of organic acetylsilane and phenolic resin with low molecular weight. Difference: silicone rubber is a linear structure after molecular reinforcement, vulcanized and cross-linked into a three-dimensional structure. When the trace hydroxyl terminated is contained, the aging resistance is not good enough. The light transmittance of silica reinforcement is poor. The mechanical properties are generally better than that of silicone resin; Large elasticity, soft, good heat and weather resistance, small internal stress, the disadvantage is that the gap between the molecular chain is large, air permeability, oxygen permeability, moisture permeability. The bonding strength is generally in the range of - 50 - 200. Silicone resin is a three-dimensional structure with a larger structure. When it contains trace terminal hydroxyl groups, it is much better than silicone rubber. It has high hardness, good light transmittance, low air permeability, moisture permeability and oxygen permeability, and its mechanical properties are generally worse than those of silicone rubber.