Why does rubber flange gasket need secondary vulcanization

Why does rubber flange gasket need secondary vulcanization

April 28, 2021

Recently, due to the continuous increase in orders, RSL rubber seals has added a high-power oven to cope with the increasing orders.
This oven is not for toasting bread, but for the secondary vulcanization of rubber products.


Everyone knows that the common production processes of rubber products include hot press molding, injection molding, extrusion, etc. After production, some rubber products need to be vulcanized twice, which is also called secondary vulcanization. In fact, we can see from the naked eye after molding. It is already a good product, and it can be used normally. Why do you need to re-vulcanize it? Today, RSL rubber will explain to everyone.

rubber flange gasket

The first thing to note is that not all rubber products need secondary vulcanization, but according to the different raw material formulations, some can be directly molded at one time, but some special materials such as fluorine rubber products and some EPDM rubber products are The need for secondary vulcanization is because firstly, during the primary vulcanization of these materials, the peroxides inside will decompose and react with high polymers, resulting in some low-molecular compounds (such as benzene, benzoic acid, etc.). These low-molecular-weight compounds Compounds mixed in rubber will reduce the mechanical properties of the rubber and reduce its life. Therefore, secondary vulcanization is often used to decompose and volatilize low-molecular compounds.
Second, when the primary vulcanization is completed, the rubber molecules may not be fully cross-linked (insufficient vulcanization), and the secondary vulcanization can make the vulcanization more fully and uniformly, thereby improving the mechanical properties and durability of the rubber.
Third, it is secondary vulcanized. For example, after the secondary vulcanization of a large number of EPD rubber products used in automobiles, the peculiar smell can be removed and the comfort of the car occupants can be improved. In order to reduce costs and increase production capacity, the Fourth Rubber Products Company often shortens the primary vulcanization time, and then extends the time during the secondary vulcanization to ensure that the product is fully vulcanized while also improving its own competitiveness.

After the above introduction, do you have a better understanding of our rubber product secondary vulcanization process?

RSL Rubber has focused on OEM rubber products for 30 years, providing overall solutions from material research and development, mold development, to rubber product manufacturing. Welcome to visit the factory or visit our official website to learn more.