Vulcanization of silicone rubber products refers to the process of chemical crosslinking of silicone rubber molecules under the action of vulcanizing agent and certain vulcanization time, temperature and pressure. We all know that low-temperature vulcanization is good for product performance, but the output of products will be reduced and the cost will be increased. Therefore, many manufacturers will think how to improve the vulcanization speed of silicone rubber products, shorten the molding time, improve the production efficiency and reduce the production cost without affecting the product quality?

Selection of vulcanizing agent:

The commonly used vulcanizing agents include peroxide vulcanizing agent and platinum vulcanizing agent. Platinum vulcanizing agent mainly displays the following points in the production process: excellent dispersion, low volatility, fast vulcanization speed and low-temperature molding. Colorless, tasteless and environment-friendly, in line with FDA and German flgb. Most peroxides are easy to turn yellow and taste. With the increase of vulcanization inhibitor, the vulcanization rate becomes slower. With the increase of vulcanization accelerator, the vulcanization speed is accelerated!

Setting of process conditions:

Vulcanization temperature is the basic condition of vulcanization reaction (crosslinking reaction) of silicone rubber, which directly affects the vulcanization speed of silicone rubber and the quality of products. Like all chemical reactions, the vulcanization reaction accelerates with the increase of temperature, which is easy to form more low sulfur cross-linking bonds; If the vulcanization temperature is low, the speed is slow, the formation efficiency is low, and more polysulfide cross-linking bonds are generated. The vulcanization temperature is also generally applicable to van der Hoff's law, that is, for every 8-10 increase in temperature, the reaction rate is about doubled. The increase of pressure will accelerate the vulcanization rate of silicone rubber.

The difference between double 24 and double 25:

Double two four: double two four has the advantages of low decomposition temperature and fast decomposition speed. Therefore, it is a commonly used vulcanizing agent for extrusion compound. However, due to the low decomposition temperature, the coke burning performance is poor, so the dosage should be as small as possible. The decomposition products are 2,4-dichlorobenzoic acid and 2,4-dichlorobenzene, which are toxic and affect the heat resistance of rubber products. Because carbon black affects the vulcanization of double two four, it can not be used in compounds containing carbon black.

Double 25: double 25 has high decomposition temperature and good coke burning performance. Since no products with carboxyl groups are produced during decomposition, the thermal stability of the compound is not affected. Double 25 can be used for compounds containing carbon black and has a wide range of applications. When double 25 vulcanization is adopted, the compression deformation of vulcanizate is low and the elongation is high.

In addition, when the amount of peroxide exceeds the appropriate amount, the elongation and tear strength of vulcanizate will be reduced, and the effect of double two four will be greater.

Double 24 is generally used for extrusion and double 25 is used for molding.

Double two four is generally used in extrusion calendering process. The vulcanization temperature is generally 120 ℃, double two five is generally used for molding, and the vulcanization temperature is 170 ℃. Another difference is that Shuang 25 is a special vinyl curing agent.

Other aspects:

Change the discharge mode of silicone rubber raw materials, so that the silicone rubber raw materials can cover the whole inner wall of the mold as much as possible during the pressurization process of the mold. The molding operator shall speed up the operation speed and minimize the time outside the mold, so as to stabilize the mold temperature of silicone rubber products and improve the vulcanization speed of silicone rubber products.