How to solve the problem of yellowing of silicone

- May 18, 2020-

We will encounter some product discoloration during normal work. The latex tube inside will be white when stored at room temperature, and the silicone tube will be yellow at high temperature. The existing problem is that the transparent silicone tube that needs to be contacted with food, after being placed under the high temperature of 200 ℃ for 4 hours, the yellowing phenomenon appears. What is going on?


Using silica gel high anti-yellow vulcanizing agent C-15, the problem may be solved. General food-grade products have this requirement. To prevent yellowing by secondary sulfuration, use anti-yellowing catalyst + anti-yellowing agent, both. But these two things will make it a little sticky in the production of oil pressure. It is something to be aware of. Add 2-3 parts per thousand hydrogen-containing silicone oil according to the amount of silica gel. High hydrogen-containing silicone oil can solve the yellowing problem, but the product may be a bit For brittle and sticky molds, a layer of silicone oil can be sprayed on the mold to solve the problem of demolding. Otherwise, only platinum bridges are used.

Silicone heater manufacturers analyze for you: It is of course a good idea to use anti-yellowing agents and anti-yellowing vulcanizing agents. However, it should also be noted that the silicone tube you are using is ideal. You can not add too much release agent, zinc stearate, so you should communicate with the supplier if there is already hydrogen-containing silicone oil to provide anti-yellowing effect Powder is very important. If the iron content is too high, it will turn yellow.

You can test it with a common vulcanizing agent (without anti-yellowing agent) compared with the vulcanizing agent with anti-yellowing agent. Be careful not to add zinc stearate release agent. If it still doesn't work, it is recommended that you use another compound or use platinum vulcanizing agent. If there is sulfur or sulfur carriers in the environment (such as sulfur-cured products that have just been baked in the oven), the silicone tube will also turn yellow.