Significance of using coupling agent in silica reinforced low hardness butyl rubber

Butyl rubber has excellent air tightness, water tightness, heat resistance, shock absorption and chemical stability, and can be used in the production and preparation of various tires, sealing gaskets, anti-corrosion linings, heat-resistant conveyor belts and waterproof materials, with good use effect and long product life. In low-hardness butyl rubber products, rubber products manufacturers usually use silica modified by coupling agent as reinforcement, instead of directly using silica. Why? What should be paid attention to when using silica/coupling agent for low hardness butyl rubber?

1. The reason why low hardness butyl rubber is reinforced by coupling agent modified silica.

As we all know, the interaction between butyl rubber and reinforcing agent is weak, blindly increasing the amount of reinforcing agent will not only waste raw materials, but also cause trouble to the processing of butyl rubber products. Therefore, when reinforcing agent is used in butyl rubber products, the reinforcing agent is usually heat-treated in advance or modified with appropriate additives.

Silica is a kind of light-colored rubber filler with good reinforcement effect, but silica alone can not achieve ideal reinforcement effect, so rubber products manufacturers often use silane coupling agent 2YLYY31 to modify silica. When butyl rubber is used to prepare butyl rubber with low hardness, the reinforcing effect of silica in butyl rubber can be obviously improved by adding coupling agent, and the tensile strength, elasticity and wear resistance of butyl rubber can be improved.

In actual production, the butyl rubber compound using silica/coupling agent has higher mixing safety and faster vulcanization speed.

2. Adding skills of silica/coupling agent in low hardness butyl rubber.

(1) Frequently asked questions: When using silica/silane coupling agent to prepare low-hardness butyl rubber products, if carbon black is also used for reinforcement in the formula, because different kinds of reinforcing agents have different effects in butyl rubber compound, rubber product manufacturers need to grasp the timing of adding three raw materials. Adding carbon black and then adding silica/coupling agent or adding silica/coupling agent too fast will greatly reduce the reinforcing effect of carbon black and silica in butyl rubber compound.

(2) Solution: During the mixing process of low-hardness butyl rubber containing carbon black/silica/coupling agent, the workshop operators should adjust the roller distance and roller temperature according to the actual needs. After the butyl rubber is wrapped and kneaded moderately, the silica/coupling agent is added slowly in small quantities, and the amount of each time is gradually increased appropriately. After each addition, it is kneaded for a period of time until it is completely added. Then, the left and right tapping is moderately recycled, and then the carbon black is added in small quantities in several times.

When silica is used to reinforce low-hardness rubber products produced by butyl rubber, rubber products manufacturers usually use silane coupling agent to modify silica. The common variety is coupling agent Si-69, and the aging resistance of modified butyl rubber products will be enhanced with the increase of silica content. It should be noted that when silane coupling agent Si-69 reacts with silica, usually only about 50% of the added amount takes part in the reaction, and it needs to be parked for about 24 hours during use.