Selection principle of silane coupling agent

Coupling agent is a kind of substance with amphoteric structure. Some groups in their molecules can react with chemical groups on the inorganic surface to form chemical bonds; Part of the group has the nature of organophiles, which can chemically react with organic molecules or produce strong intermolecular interactions, thereby firmly combining two materials with completely different properties.

Selecting a suitable coupling agent can improve the dispersion state of the inorganic filler in the polymer matrix, and improve the mechanical properties and performance of the filled polymer material.

The hydrolysis speed of the silane coupling agent is taken from the silicon functional group Si-X, while the reactivity with organic polymers is taken from the carbon functional group C-Y. Therefore, for different substrates or processing objects, it is very important to choose a suitable silane coupling agent.

Selection principle of coupling agent

1. Silane coupling agents are mainly suitable for glass fiber and silicon-containing fillers, such as quartz, wollastonite, etc., and can also be used for some metal oxides and Hydroxide, but not CaCO3. The resin is mainly a thermosetting resin.

2. Titanate coupling agent has a wide range of applications for fillers, such as CaCO3, titanium dioxide, etc., and can also be used in glass fibers. The resin is mainly a thermoplastic resin.

3. Acidic fillers should use coupling agents containing basic functional groups, while basic fillers should use coupling agents containing acidic functional groups.

4. The amount of coupling agent added. The amount of silane coupling agent can be about 1% of the filler; the amount of titanic acid is generally 0.25~2% of the filler.

5. Some surfactants will affect the performance of titanate coupling agents, such as HSt, etc., so they must be fully mixed with fillers, coupling agents, and resins. Mix and add.

6. Most titanate coupling agents are prone to transesterification reactions with ester plasticizers. Therefore, such coupling agents need to be coupled After the agent is added, it can be added. The combination of titanate and silane coupling agent has a good synergistic effect.