Curing is usually achieved by silanol condensation to form a silicone chain. When the condensation reaction is proceeding, the steric hindrance is increased due to the gradual decrease in the concentration of silanol, and the fluidity is poor, resulting in a decrease in the reaction rate. Therefore, in order to completely cure the resin, it is necessary to heat and add a catalyst to accelerate the reaction. Many substances can be catalyzed by silanol condensation reactions, including acids and bases, soluble organic salts of lead, cobalt, tin, iron and other metals, organic compounds such as dibutyltin dilaurate and the like.
The properties of the final processed article of silicone depend on the number of organic groups contained (i.e., the ratio of R to Si). Generally, a silicone resin having practical value has a ratio of R to Si in a molecular composition of 1.2 to 1.6. The general rule is that the smaller the value of R:Si, the more the obtained silicone resin can be cured at a lower temperature; the larger the value of R:Si, the more the silicone resin obtained needs to be cured at 200-250. After baking at a high temperature of °C for a long time, the resulting paint film has poor hardness, but the thermoelasticity is much better than the former.
In addition, the ratio of methyl groups to phenyl groups in the organic group also has a large effect on the properties of the silicone resin. The lower the phenyl content in the organic group, the softer the resulting paint film, the faster the condensation, and the higher the phenyl content, the harder the resulting paint film and the more thermoplastic. The phenyl content is between 20 and 60%, and the film has the best bending resistance and heat resistance. In addition, the introduction of phenyl can improve the compatibility of silicone with pigments, and also improve the compatibility of silicone with other silicone resins and the adhesion of silicone to various substrates.
Contact：Sharon Song(Sales manager)
Zhejiang Runhe Organosilicone New Material Co.,Ltd(Factory)
Zhejiang Runhe Chemical New Material Co.,Ltd(Exporter)
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