Secondary vulcanization, English name is (postcure), is the product formed from the machine, and then put the produced product in the oven for a period of time (180 degrees to 200 degrees, usually two or three hours), which is called secondary vulcanization.

Secondary vulcanization is also called post vulcanization. It is commonly used for vulcanization of silicone rubber, fluorosilicone rubber and fluorosilicone rubber.

Function of secondary vulcanization: when silicone rubber is vulcanized with peroxide, after peroxide decomposition initiates polymer reaction, low molecular compounds (such as benzene and benzoic acid) are generated, which will affect the mechanical properties of rubber. Moreover, after the silicone rubber is heated and formed in the first stage, its crosslinking density is not enough. It is necessary to make further vulcanization reaction to increase the density of silicone rubber. The tensile strength, resilience, hardness, swelling degree, density and thermal stability are greatly improved than those of primary vulcanization. If secondary vulcanization is not carried out, the performance of the produced silicone may be affected to a certain extent, The parameters of primary vulcanization and secondary vulcanization may be different, which is related to the actual operation!

There are many kinds of silica gel vulcanization, including high temperature and room temperature. Take high-temperature silica gel for example. Before vulcanization, it is what we usually call raw rubber. Compound is made by refining many additives such as vulcanizing agent and release agent together with raw rubber. It can be seen from the appearance. It breaks when pulled by hand. It has no elasticity. If the mixed rubber is vulcanized at a certain temperature, the product can be obtained, just like the silicone mobile phone case we usually see... As for whether it is poisonous or not, as long as the manufacturer can provide food certification, it is generally non-toxic.