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. It can be used in the production and preparation of various tires, sealing washers, anti-corrosion linings, heat-resistant conveyor belts, and waterproof materials. It has good use effect and long product life. In low hardness butyl rubber products, rubber manufacturers usually use silica modified by coupling agent for reinforcement, instead of directly using silica. Why? What should be paid attention to when using silica/coupling agent for low hardness butyl rubber?
1. Reasons for using coupling agent to modify white carbon black for reinforcing low hardness butyl rubber
As we all know, the role between butyl rubber and reinforcing agent is weak. blindly increasing the amount of reinforcing agent will not only cause waste of raw materials, but also cause problems for butyl rubber product processing if the reinforcing agent cannot be uniformly dispersed in the rubber material. Therefore, when using the reinforcing agent in butyl rubber products, the reinforcing agent is usually heat treated in advance or modified with an appropriate amount of additives.
Silica is the product with the best reinforcement effect among light colored rubber fillers, but the use of silica alone cannot achieve the ideal reinforcement effect. Therefore, rubber product manufacturers often use silane coupling agent 2YLYY31 to modify silica. When butyl rubber was used to prepare low hardness butyl rubber, coupling agent in white carbon black could significantly improve the reinforcing effect of white carbon black in butyl rubber, and improve the tensile strength, elasticity, wear resistance and other indicators of butyl rubber.
In actual production, the butyl rubber compound with silica/coupling agent has higher mixing safety and faster curing speed.
2. Adding skills of silica/coupling agent in low hardness butyl rubber
(1) Common problems: When white carbon black/silane coupling agent is used to prepare low hardness butyl rubber products, if carbon black reinforcement is also used in the formula, because different types of reinforcing agents have different effects in butyl rubber, rubber product manufacturers need to master the time to add three kinds of raw materials. Adding carbon black and then adding white carbon black/coupling agent or adding white carbon black/coupling agent too fast will lead to carbon black The reinforcing effect of silica in butyl compound is greatly reduced.
(2) Solution, Then carbon black is added in small amounts for many times to ensure that butyl rubber has good flexibility and fluidity, and effectively avoid problems such as bubbles on the surface of low hardness butyl rubber products and broken edges at the parting line.
When white carbon black is used for reinforcing low hardness rubber products produced by butyl rubber, rubber product manufacturers usually use silane coupling agent to modify white carbon black. Common varieties are coupling agent Si-69. The aging resistance of modified butyl rubber products will be enhanced with the increase of the amount of white carbon black. It should be noted that in general, when silane coupling agent Si-69 reacts with silica, only about 50% of the added amount usually participates in the reaction, and it needs to be parked for about 24 hours during use.