Secondary vulcanization, also known as post vulcanization or secondary vulcanization, refers to the vulcanization of rubber products to a certain degree, removing heat sources to continue the process of heating vulcanization.
In a broad sense, when the rubber products are vulcanized to a certain extent, even if they are not heated, they can continue to deepen the vulcanization process under the action of residual heat, or in the process of product storage, or continue to cross-linking phenomenon under the dynamic action. Of course, it also includes the processing technology of continuous heating for secondary vulcanization; the purpose of secondary vulcanization is to further crosslink rubber products, improve the mechanical properties and compression permanent deformation properties of rubber products; the method of secondary vulcanization is hot air vulcanization in oven or hot air secondary vulcanization in vulcanizing tank; At present, many rubber seals or rubber products manufacturers use the secondary vulcanization technology to make rubber seal products. With the change of the times, the technology is constantly updated and optimized!
The effect of the second vulcanization of silica gel: when the silicone rubber is vulcanized with peroxide, the decomposition of peroxide will lead to the reaction of polymers, resulting in the formation of low molecular compounds (such as benzene and benzoic acid), which will affect the mechanical properties of the rubber. Moreover, after the first stage of heating and forming, the crosslinking density of silicone rubber is not enough, and further vulcanization is needed to increase the density of silicone rubber. The tensile strength, resilience, hardness, swelling degree, density and thermal stability are all greatly improved compared with that of the first vulcanization. If the second vulcanization is not carried out, the performance of silicone produced may be affected to some extent, No better product can be obtained. The parameters of primary vulcanization and secondary vulcanization may be different, which is related to the actual operation! There are many kinds of silicone vulcanization, including high temperature and room temperature. According to the example of high-temperature silica gel, we usually call raw rubber before vulcanization. Rubber mixing is to refine many auxiliary agents such as vulcanizing agent and release agent together with raw rubber. It can be seen from the appearance. It's broken when you pull it with your hand. It's not elastic. If we vulcanize the mixed rubber at a certain temperature, we can get the products, as we usually see: silica gel bottle cover, silica gel bracelet, silica gel milk bottle cover, silica gel sealing ring, silica gel tray, silica gel pad, silica gel mobile phone cover, etc., as long as it is a regular manufacturer, using qualified silica gel raw materials, the silica gel products are generally none Toxic.