What is a coupling agent? Titanium ester coupling agent manufacturers state that coupling agents are substances with two structural properties, and some functional groups in their molecules can react with chemical groups on the surface of inorganic materials to form chemical bonds; The other part of the functional group has a pro organic property, which can react chemically with organic molecules or generate strong intermolecular interactions, firmly bonding two materials with completely different properties. Due to the fact that most coupling agents can chemically treat the surface of fillers, the effect is very good, which can effectively improve the dispersion state of inorganic fillers in polymer matrices, enhance the mechanical properties and usability of filled polymer materials.
Titanium ester coupling agent manufacturers have learned that coupling agents can be divided into silane coupling agents, titanium ester coupling agents, aluminum ester coupling agents, zirconate coupling agents, bimetallic coupling agents (aluminum zirconate, aluminum titanium composite coupling agents), rare earth coupling agents, phosphorus containing coupling agents, boron containing coupling agents, etc. Among them, silane coupling agents were studied and applied earlier, while titanate coupling agents appeared as early as the late 1970s. It has a good coupling effect on many dry powders. The following will briefly introduce the commonly used coupling agents and their applications in production.
The reason why it is called silane coupling agent is because its central atom is silicon (Si), and its molecular structure is R-Si-X3, where R is a hydrophobic group such as vinyl, epoxy, amino, methacrylate, sulfate, etc. X is a hydrophilic group that can be hydrolyzed, such as alkoxy, ethoxy, and chlorine. The addition amount is usually about 1% of the filler.
So what are the principles for selecting coupling agents? Take a look at the introduction of the family members of the titanium ester coupling agent factory.
The manufacturer of titanium ester coupling agent said that its structure is similar to titanium ester coupling agent, with two active groups in the molecule, one of which can interact with the surface of inorganic fillers; Another type can entangle with resin molecules, leading to coupling between inorganic fillers and matrix resin. It is light in color, non-toxic, and easy to use. Its thermal stability is better than that of titanium ester coupling agents, and its price is only half of that of titanium ester coupling agents.
The dosage of aluminum ester coupling agent is generally 0.3% to 1.0% of the composite material filler. For plastic hard products formed by injection molding or extrusion molding, the filler content is about 1.0%. For products formed by other processes, soft products, and foam products, the filler content is about 0.3% to 0.5%. The usable amount of high specific surface area fillers such as aluminum hydroxide, magnesium hydroxide, and white carbon black is 1.0% to 1.3%
Zirconium coupling agents can not only promote the binding of inorganic and organic substances, but also improve the performance of the filler system. Its characteristic is that it can significantly reduce the viscosity of the filler system, suppress the interaction between filler particles, reduce the viscosity of the filler system, thereby improving the dispersibility of the system and increasing the filling amount.
Zirconium coupling agents have good modification effects on calcium carbonate, silicon dioxide, aluminum oxide, titanium oxide, and clay. Mainly suitable for different polymer filling systems such as polyolefin, polyester, epoxy resin, nylon, polyurethane, synthetic rubber, etc
Unsaturated organic acids form coordination metal complexes with trivalent chromium atoms. In fiberglass, it has a good application effect.
Organic chromium coupling agents have low cost, but their variety is single, and their application range and coupling effect are not as good as silane coupling agents and titanium ester coupling agents. The main reason is the toxicity of chromium ions and their pollution to the environment, which has led to a gradual decrease in current usage.
Aluminum titanium composite coupling agents use aluminum instead of some central atoms as the coupling agent, reducing the content of expensive titanium in the coupling agent and lowering costs. It combines the characteristics of titanium and aluminum coupling agents, and its coupling effect is superior to that of single titanium salts, aluminum salts, and their simple mixtures.