According to the chemical structure and composition of the coupling agent, it is divided into four categories: organic chromium complexes, silanes, titanates and aluminates:
1. Chromium Complex Coupling
Chromium complex coupling agent was developed in the early 1950s. The synthesis and application technology of metal chromium complexes formed by unsaturated organic acids and trivalent chromium ions are relatively mature, and the cost is low, but the variety is relatively simple.
2. Silane coupling agent
The general formula of silane coupling agent is RSiX3, in which R represents amino, mercapto, vinyl, epoxy, cyano and methacryloyloxy groups. These groups and different matrix resins have strong The reactivity of X represents an alkoxy group (such as methoxy, ethoxy, etc.) that can be hydrolyzed. Silane coupling agent has several types of KH550, KH560, KH570, KH792, DL602, DL171 in China.
3. Titanate coupling agent
According to their unique molecular structure, titanate coupling agents include four basic types: ①Monoalkoxy type coupling agents are suitable for a variety of resin-based composite material systems, especially suitable for free water, only containing Filling system with chemically bonded water or physical water; ②Monoalkoxy pyrophosphate type coupling agent is suitable for various resin-based composite material systems, especially suitable for filler systems with high moisture content; ③Chelation type This type of coupling agent is suitable for various resin-based composite material systems. Because of their very good hydrolysis stability, this type of coupling agent is especially suitable for water-containing polymer systems; ④ The ligand type of this type of coupling agent is used in a variety of It has good coupling effect in resin-based or rubber-based composite material systems, which overcomes the shortcomings of general titanate coupling agents used in resin-based composite material systems.
4. Other coupling agents
Zirconium coupling agents are low molecular weight inorganic polymers containing zirconium aluminate. It not only promotes adhesion between different substances, but also improves the properties of composite systems, especially rheological properties. This type of coupling agent is suitable for both thermosetting resins and thermoplastic resins. In addition, there are magnesium-based coupling agents and tin-based coupling agents.
In reinforced plastics, chemical substances that can improve the bonding force between the resin and the reinforcing material interface.
A substance that promotes or establishes a stronger bond at the interface between the resin matrix and the reinforcing material.
Note: The coupling agent can be applied to the reinforcing material or added to the resin, or a combination of both.