Rubber products are familiar to everyone. The common production methods include hot pressing molding, injection molding, extrusion, etc. After production, some rubber products still require secondary vulcanization, also known as two-stage vulcanization. In fact, after the products are formed, from an external perspective, they already appear to be good products and can be used normally. Why do they need to undergo secondary vulcanization again? Today, Yongyong Silicone Rubber will have a detailed discussion with everyone about this.
First of all, it should be noted that not all rubber products require secondary vulcanization. It is only because of the different raw material formulations that some can be directly formed in one step, but for some special materials such as fluorine rubber products and certain EPDM rubber products, secondary vulcanization is necessary. This is because during the first vulcanization of these materials, the peroxides inside will decompose and undergo polymerization reactions, generating some low-molecular compounds (such as benzene, benzoic acid, etc.). These low-molecular compounds mixed in the rubber will reduce the mechanical properties of the rubber and shorten its lifespan. Therefore, secondary vulcanization is commonly used to decompose and volatilize these low-molecular compounds.
Secondly, when the first vulcanization is completed, the rubber molecules may not have fully cross-linked (the vulcanization is insufficient). The second vulcanization can make the rubber vulcanized more thoroughly and evenly, thereby improving the mechanical properties and durability of the rubber.
Thirdly, it undergoes a second vulcanization process. For example, EPDM rubber products widely used in automobiles can eliminate odors after the second vulcanization, thereby enhancing the comfort of the car occupants. Fourthly, rubber product companies often shorten the first vulcanization time to reduce costs and increase production capacity. Then, during the second vulcanization process, they extend the time to ensure that the products are fully vulcanized, which also helps to enhance their competitiveness.
After the above introduction, do you now have a deeper understanding of our rubber products' secondary vulcanization process?
Yongyong Silicone Rubber has been dedicated to rubber products for 25 years. We offer a complete solution covering material research, mold development, and manufacturing of silicone rubber products. Welcome to visit our factory for a tour.
