In the production process, the silica gel comes out of the hydraulic press and is called a period of vulcanization. During the first vulcanization process, only the silica gel is cooked, but the vulcanizing agent decomposer and release agent decomposer contained in the silica gel cannot be completely discharged.
At this time, you need to put the silicone products in the oven to bake. Generally, the tableware is 200 degrees for 4 hours. According to different requirements, the temperature and duration of the secondary vulcanization are different. Some industrial miscellaneous parts do not need secondary vulcanization at all.
Secondary vulcanization is also called post-vulcanization. It is commonly used in the vulcanization of silicone rubber, fluorine rubber and fluorosilicone rubber. The role of secondary vulcanization: When silicone rubber is vulcanized with peroxide, the peroxide decomposes and initiates a polymer reaction, and low The presence of molecular compounds (such as benzene and benzoic acid, etc.) in the rubber will affect the mechanical properties of the rubber. Moreover, after the first stage of heating and molding of the silicone rubber, its crosslinking density is not enough, and it needs to be further vulcanized to increase the density of the silicone rubber. Tensile strength, resilience, hardness, swelling degree, density, and thermal stability are all greatly improved than one-time vulcanization.
If the secondary vulcanization is not carried out, the performance of the produced silica gel may be affected to a certain extent and better performance products cannot be obtained. The parameters of the primary vulcanization and the secondary vulcanization may be different, which is related to the actual operation! How much silicone is vulcanized There are high temperature and room temperature. Take high temperature silica gel for example. Before vulcanization, it is what we usually call raw rubber. The rubber compound is made by refining many additives such as vulcanizing agents, mold release agents, etc., together with the raw rubber. It can be seen from the appearance. It breaks when you pull it by hand, and there is no elasticity. If the mixed rubber is vulcanized and molded at a certain temperature, the product can be obtained.