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Why do silicone rubber products undergo secondary curing?
- 2019-04-30-

The secondary vulcanization oven, also known as vulcanization oven, post-vulcanization oven, is a hot-air circulating constant temperature oven designed for use in vulcanized or cured products. The oven process temperature is about 200 degrees, mainly used in automotive rubber and plastic parts, natural rubber products, synthetic rubber parts, silicone parts and so on. So why do silicone rubber products undergo secondary curing?

When silicone rubber is vulcanized by peroxide, the decomposition of the peroxide initiates the reaction of the polymer, and the formation of low molecular compounds (such as benzene and benzoic acid) in the rubber will affect the mechanical properties of the rubber. Moreover, after the silicone rubber is heated in one stage, the crosslink density is insufficient, and the further vulcanization reaction is required to increase the density of the silicone rubber. The tensile strength, resilience, hardness, swelling degree, density, and thermal stability are all more than one-time vulcanization. There is a big improvement.

If the secondary vulcanization is not carried out, the performance of the produced silica gel may be affected to some extent. The parameters of primary vulcanization may differ from the parameters of secondary vulcanization, which is related to the actual operation! There are many kinds of vulcanization of silica gel, high temperature and room temperature. Take high-temperature silica gel, it is the raw rubber we usually say before vulcanization. The rubber compound is made by refining many additives such as vulcanizing agent, mold release agent and raw rubber. It can be seen from the appearance. It is broken with a hand and has no elasticity. If the kneaded rubber is vulcanized at a certain temperature at a certain temperature, the product can be obtained.

From the viewpoint of improving the vulcanization efficiency, it is considered that the higher the vulcanization temperature, the better, but the vulcanization temperature cannot be increased indefinitely. Rubber products and silica gel products are high-molecular polymers. The high temperature causes the cracking reaction of the molecular chain of the silicone rubber, causing the cross-linking bond to break, that is, the phenomenon of "reversion to the original" occurs, thereby degrading the physical and mechanical properties of the vulcanized rubber.

Yihexing secondary vulcanization oven adopts the principle of forced convection circulation by hot air. The special liner design has the characteristics of hot air circulation and uniform temperature. Aiming at the particularity of the vulcanization process, a unique air duct is designed, and the internal circulation air volume ensures a good vulcanization effect.

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