Vulcanization system of low temperature vulcanized silicone rubber

Low temperature vulcanized silicone rubber, also known as liquid silicone rubber, is a kind of polysiloxane elastomer material with vinyl end group. Generally, the vulcanization temperature is 40 ~ 120 ℃, which is between hot vulcanization and room temperature vulcanization. It can be crosslinked by addition reaction with si-h-based energetic polysiloxane in the presence of catalyst.

The common catalyst is organic platinum complex. The new varieties are the complexes containing vinyl low molecular polysiloxane. The amount of catalyst is very small.

In order to adjust the active period of the compound and improve the storage stability, reaction inhibitors can be used, such as alkyne compounds and compounds containing amine, tin, phosphorus, etc.

The vulcanization system is more active. If it is not stored properly, the compound will be partially crosslinked at room temperature. Therefore, in addition to the use of reaction inhibitors, the compound should be made into two-component form: one component contains crosslinking agent, the other component contains catalyst, which is similar to two-component RTV silicone rubber. When using, measure and mix according to regulations. In this way, the storage life of the compound is longer, and it can reach more than one year at room temperature. The curing rate of addition molding system has a great relationship with temperature.

Addition silicone rubber can be vulcanized not only at low temperature, but also at high temperature for a short time. Generally, addition silicone rubber does not need two-stage vulcanization, because there is no low molecular polycondensation by-product during vulcanization. However, in order to reduce the compression deformation of vulcanizate, two-stage vulcanization must be carried out.