Development of Silane Coupling Agents

Silane coupling agents used in the rubber industry can improve the wear resistance and aging resistance of tires, rubber sheets, hoses, rubber shoes and other products, and can reduce the amount of NR to reduce costs.

There are many types of coupling agents; mainly include silane coupling agents, titanate coupling agent, aluminate coupling agent, bimetal coupling agent, phosphate coupling agent, borate coupling agent, chromium complex coupling agents for compounds and other higher fatty acids, alcohols, esters, etc. At present, silane coupling agents and titanate coupling agents are the most widely used.

1. The earliest silane coupling agent and its development

Silane coupling agent is the earliest research and application coupling agent. Due to its unique properties and the continuous advent of new products, its application fields have gradually expanded, and it has become an important branch of the silicone industry.

It is a kind of organic silicon product that has developed rapidly in recent years. It has a wide variety of products and a novel structure. There are more than 100 kinds of products with only known structures.

Around 1945, a series of silane coupling agents with typical structures were developed and announced by companies such as United Carbon (UC) and DOWCORNING;

In 1955, UC Company proposed the first amino-containing silane coupling agent;

A series of modified amino silane coupling agents have appeared successively since 1959;

The peroxy-containing silane coupling agents that appeared in the early 1960s and the silane coupling agents with diazo and azide structures that appeared in the late 1960s have greatly enriched the varieties of silane coupling agents.

In recent decades, with the development of glass fiber reinforced plastics, the research and development of various coupling agents has been promoted. The synthesis and application of modified amino silane coupling agents, peroxy silane coupling agents and azido silane coupling agents are the main achievements of this period.

2. The mechanism of silane coupling agents

Since silane coupling agents have these two types of chemical groups in the molecule, they can not only react with the hydroxyl groups in inorganic substances, but also interact with long molecular chains in organic substances to achieve the coupling effect. The mechanism of action is roughly divided into the following 3 steps:

(1) The X group is hydrolyzed to a hydroxyl group;

(2) The hydroxyl group and the hydroxyl group existing on the surface of the inorganic substance form a hydrogen bond or dehydrated to form an ether bond;

(3) The R group is combined with organic matter.