Why do some rubber products need two-stage vulcanization?

Date:09-04-2020
Abstract:

Rubber products are not unfamiliar to everyone. The com […]

Rubber products are not unfamiliar to everyone. The common production processes include hot compression molding, injection molding, extrusion, etc. After production, some rubber products also need to be vulcanized twice, also called two-stage vulcanization. In fact, after molding, it is from the naked eye We seem to be a good product, but it can be used normally. Why do we need to re-vulcanize it?


First of all, it should be noted that not all rubber products require secondary vulcanization, but depending on the raw material formula, some can be directly molded at one time, but some special materials such as fluororubber products and some EPDM rubber products are all The need for secondary vulcanization is that the first of these materials during the primary vulcanization, the peroxide inside will decompose and undergo a high polymer reaction, producing some low molecular compounds (such as benzene, benzoic acid, etc.), these low molecular compounds Mixing with rubber will reduce the mechanical properties and life of the rubber. Therefore, secondary vulcanization is commonly used to decompose and evaporate low molecular compounds.

Second, when the first vulcanization is completed, the rubber molecules may not be fully cross-linked (inadequate vulcanization). The second vulcanization can make the vulcanization more complete and more uniform, thereby improving the mechanical properties and durability of the rubber.


Thirdly, it is secondarily vulcanized. For example, a large number of EPD rubber products used in automobiles can be vulcanized to remove odors and improve the comfort of vehicle occupants. 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.