The root cause of the yellowing of vinyl silicone oil or raw rubber is that the vinyl is oxidized at high temperature in the presence of air. The reaction temperature should not be too high, the general batch production should not exceed 160 degrees, 2). The vacuum degree of the reaction kettle must be good, not to say the absolute pressure of the minimum pressure of 99%, nitrogen protection; 3). Vinyl sealing end agent or ring body quality is better, Cl ion and impurity sealing agent must be controlled in dozens of parts per million. Do this, general yellow change can control. The water content is related to polymerization, but it does not affect the yellowing. H2O is equivalent to an end agent, with a maximum of 107 adhesive. The lower the viscosity or the higher the vinyl content, the more likely it is to be yellowing, but controlling the above points is not a problem. There are no yellowed changes in 1, 000 CPS of vinyl silicone or 3% of raw gum.

2018-03-20