Secondary vulcanization, also called post-vulcanization or secondary vulcanization, refers to a process in which rubber products reach a certain degree of vulcanization and then the heat source is removed to continue heating and vulcanization.

Broadly speaking, when a rubber product is vulcanized to a certain extent, even if it is not heated, it can still continue to deepen the vulcanization process under the action of residual heat, or during the storage process of the product, or continue to produce cross-linking phenomena under dynamic effects. Of course, it also includes the process of continuing to heat for secondary vulcanization; the purpose of secondary vulcanization is to further cross-link the rubber products and improve the mechanical properties and compression permanent deformation properties of the rubber products; the secondary vulcanization method is oven hot air vulcanization or vulcanization Tank hot air secondary vulcanization.
At present, many rubber seals or rubber product production units use secondary vulcanization technology to produce rubber sealing products. The technology is constantly updated and optimized with the changes of the times.

The role of silicone secondary vulcanization:
When silicone rubber is vulcanized with peroxide, after the peroxide decomposes and triggers a polymer reaction, low molecular compounds (such as benzene and benzoic acid, etc.) are generated and are present in the rubber, which will affect the mechanical properties of the rubber. Moreover, after the silicone rubber is heated and molded in the first stage, its cross-linking density is not enough. It requires further vulcanization reaction to increase the density of the silicone rubber. The tensile strength, resilience, hardness, swelling degree, density, and thermal stability are all better than those of the first stage. Vulcanization has been greatly improved. If secondary vulcanization is not performed, the performance of the silicone produced may be affected to a certain extent, and products with better performance may not be obtained.

The parameters of primary vulcanization may be different from those of secondary vulcanization, which is related to actual operation. There are many types of silicone vulcanization, including high temperature and room temperature. Take high-temperature silica gel as an example. Before it is vulcanized, it is what we usually call raw rubber. The compounded rubber is made by refining many additives such as vulcanizing agents, release agents, etc. with the raw rubber. It can be seen from the appearance. It breaks when you pull it with your hands and has no elasticity.

If the mixed glue is vulcanized and molded at a certain temperature, products can be obtained, just like what we usually see: silicone bottle covers, silicone bracelets, silicone bottle covers, silicone seals, silicone trays, silicone pads, silicone Mobile phone cases etc. As long as it is a regular manufacturer and uses qualified silicone raw materials, silicone products are generally non-toxic.