The more mature mechanism of action of silane coupling agent is the chemical bond theory: silane coupling agent contains two kinds of different chemical functional groups, one end of which can react with inorganic material OH to form hydrogen bond, and condense and dehydrate under certain conditions. And curing, forming a covalent bond; the other end can be combined with the organic high-scoring material, so that a good interface between the organic polymer material-silane coupling agent-inorganic material is produced, and the two properties are greatly different. The materials are firmly bonded together.

▲The reaction process of silane coupling agent and silicon micropowder

The reaction process is divided into four steps:

The first step is that three hydrolyzed groups attached to Si in the silane coupling agent react with water to form silanol;

The second step is dehydration between silanol and condensed into Si-OH oligosiloxane;

The third step is that the Si-OH of the oligosiloxane reacts with the OH on the surface of the silicon micropowder to form a hydrogen bond;

The fourth step is to produce condensation, dehydration and curing reactions during the heating process to achieve a strong covalent bond with the silicon micropowder. The remaining two Si-OH either condense with Si-OH in other silane coupling agents or remain in a free state.

3. Selection of silane coupling agent

The surface modification technology of silicon micropowder is a technology closely related to application technology, and it is highly targeted from the application point of view. Since the hydrolysis effect of the silane coupling agent depends on Si-X, the reactivity with the organic polymer material depends on C-Y. Therefore, it is important to select a suitable silane coupling agent for different substrates or treated objects.

There are dozens of kinds of silane coupling agents: amino group, chlorine group, alkenyl group, epoxy group, methacryloxy group, anthracene group, cationic group, difunctional group and the like.

The selection method is mainly pre-selected by experiments, and should be based on the structure and properties of the silane coupling agent and the mechanism of interaction with the silicon micropowder. At the same time, it is necessary to comprehensively consider the composition of the downstream product base and the effect on the reaction of the silane coupling agent.

In addition, the selection of the silane coupling agent should also consider whether two or more coupling agents are selected. In some cases, it is necessary to select two coupling agents, which can achieve synergistic and multifunctional effects. If more than two coupling agents are selected, careful consideration should be given to which coupling agent is added first or later.

Common grade HTV silicone rubber,pls check MY D7125