Secondary vulcanization, also known as post-vulcanization or Secondary sulfide, refers to the vulcanization of rubber products to a certain degree, remove the heat source to continue the process of heating vulcanization. Widely used in silicone rubber, fluorine rubber and fluorine silicone rubber vulcanization.
Effect of secondary vulcanization: When silicone rubber is vulcanized by peroxides, the decomposition of peroxides leads to the reaction of high polymers and the formation of low molecular compounds in rubber will affect the mechanical properties of rubber.
Moreover, the cross-linking density of silicone rubber is not enough after the first stage of heating forming, so the density of silicone rubber can only be increased by further vulcanization reaction. The tensile strength, resilience, hardness, swelling degree, density and thermal stability are improved greatly compared with primary curing. If there is no secondary vulcanization, the performance of silicone produced may be affected to a certain extent, cannot be better products.
Although the process of secondary vulcanization is simple, it is necessary to comprehensively evaluate all production processes of silica gel products during the process of secondary vulcanization, and reasonably arrange the timing of secondary vulcanization according to these production processes. Improper operation will affect the operation of subsequent processes.
In a broad sense, rubber products are vulcanized to a certain extent, even without heating, it may continue to deepen the vulcanization process under the action of waste heat, or in the process of product storage, or under the dynamic action of continued cross-linking phenomenon.
Of course, it also includes the processing technology of further heating for the Secondary sulfide. The purpose of secondary vulcanization is to improve the mechanical properties and compression permanent deformation properties of rubber products by further cross-linking them. The method of secondary vulcanization is oven hot air vulcanization or the use of hot air vulcanization tank secondary vulcanization.
At present, many rubber seals or rubber products production units use secondary vulcanization technology to produce rubber seal products. The technology has been constantly updated and optimized with the changes of The Times.