1. The function of silane coupling agents

(1) Cross-linking

Once the silane is grafted into the polymer backbone, it can link the polymer molecules together through the formation of siloxane bonds, thereby creating a three-dimensional network structure. This "crosslinking" is activated by the surrounding moisture, and this activation can be carried out at room temperature. Silane coupling agents can provide coatings, adhesives, sealants and composites with better thermal stability, creep resistance, hardness and chemical resistance.

(2) Improve adhesion

Silanes can provide better substrate adhesion to adhesives, sealants and coatings, especially under humid and hot conditions. Silane coupling agents are usually used to improve the adhesion of glass, minerals and metals, and can have a very good effect on difficult-to-handle substrates, such as polyamide, sheet molding material (SMC), acrylic resin, polyvinyl chloride (PVC), etc.

(3) Coupling

The silane coupling agent application is wide. Silane coupling agents can couple inorganic pigments and fillers with organic resins. Coupling generally improves the moisture and chemical resistance of coatings, adhesives or composites.

(4) Dispersion

Silane coupling agents help to disperse inorganic pigments and fillers in coatings and sealants. Better dispersion usually results in lower viscosity of the finished product, higher retention of pigments and fillers, and can improve the hiding power of the coating.

2. The choice of silane coupling agents

There are many changes in functions of silane coupling agent. The most basic point of the selected silane is that it has the reactivity that can react with the resin, so as to realize its value.

At present, epoxy silane is commonly used in water-based coatings and adhesive systems. Occasionally, it is necessary to use other coupling agents with different functional groups for compounding. Considering that the epoxy functional group will react with functional groups such as amino, mercapto, hydroxyl, carboxyl, etc., select the appropriate product according to the needs such as whether a reaction is required or not.