Composition structure of organic silicone resin
Source: | Author:ZINCA | Published time: 26 days ago | 9 Views | Share:

    Curing is usually achieved by condensation of siliconols to form silicon oxygen chains.When the condensation reaction is in progress, the reaction rate decreases due to the gradual reduction of the concentration of silanol, increasing steric resistance and poor fluidity.Therefore, to cure the resin completely, the reaction must be accelerated by heating and adding catalysts.Many substances catalyze the condensation of siliconols, including acids and bases, soluble organic salts of lead, cobalt, tin, iron, and other metals, and organic compounds such as tin dibutyl dilaurate.

    The properties of the finished product of silicone depend on the number of organic groups (the ratio of R to Si).The ratio of R to Si in the molecular composition of general practical silicone resins is between 1.2 and 1.6.As a general rule, the smaller the R: Si value is, the better the cured silicone resin will be at lower temperatures.The higher the R: Si value is, the cured silicone resin needs to be baked for a long time at 200~250℃. The hardness of the obtained film is poor, but the thermal elasticity is much better than the former.

    In addition, the ratio of methyl to phenyl groups in organic groups also has a great influence on the properties of silicone resins.The lower the content of phenyl in the organic group, the softer the film, the faster the condensation, the higher the content of phenyl, the harder the film, the more thermoplastic.Phenyl content between 20 ~ 60%, the best bending resistance and heat resistance of the film.In addition, the introduction of phenyl can improve the compatibility of silicone resin with pigments, silicone resin with other silicone resins and silicone adhesion to a variety of substrates.