Two commonly used methods of using silane coupling agents

Surface pretreatment method

Prepare a dilute solution of 0.5-1% concentration of silane coupling agent, and apply a thin layer on the clean surface to be adhered. After drying, the adhesive can be applied. The solvents used are mostly water, alcohol, or a mixture of water and alcohol, and it is advisable to use water without fluoride ions and inexpensive and non-toxic ethanol and isopropanol.

Except for aminoalkylsilane, solutions prepared with other silane coupling agents require the addition of acetic acid as a hydrolysis catalyst and the adjustment of pH to 3.5-5.5. Long chain alkyl and phenylsilane are not suitable for use as aqueous solutions due to their poor stability. During the hydrolysis process of chlorosilanes and ethoxysilanes, there is a serious condensation reaction, and they are not suitable for use as aqueous solutions or aqueous alcohol solutions. Instead, they are often used as alcohol solutions. For silane coupling agent with poor water solubility, 0.1~0.2% (mass fraction) of non-ionic surfactant can be added first, and then water can be added to process it into water lotion for use.

Migration Law

Directly add silane coupling agent to the adhesive component, usually in an amount of 1-5% of the base resin.

After gluing, the coupling agent molecules migrate to the bonding interface through molecular diffusion, resulting in coupling action. For adhesives that need to be cured, they need to be left for a period of time after coating to allow the coupling agent to complete the migration process and achieve better results.

In practical use, coupling agents often form a deposition layer on the surface, but only the single molecular layer actually works, so the amount of coupling agent used does not need to be too much.