Follow the titanate coupling agent manufacturer to see what is a coupling agent and its selection principles
What is a coupling agent? The titanate coupling agent manufacturer said that the coupling agent is a substance with a two-property structure. Some groups in its molecule can react with chemical groups on the surface of inorganic materials to form chemical bonds; another part of the groups have organic affinity. It can chemically react with organic molecules or produce strong intermolecular interactions, so that two materials with completely different properties can be firmly combined. Since most coupling agents can chemically treat the surface of the filler, the effect is very good, which can effectively improve the dispersion state of the inorganic filler in the polymer matrix, and improve the mechanical properties and performance of the filled polymer material.
Manufacturers of titanate coupling agents have learned that coupling agents can be divided into silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconate coupling agents, and bimetallic coupling agents (aluminum-zirconium coupling agents). salt, aluminum-titanium composite coupling agent), rare earth coupling agent, phosphorus-containing coupling agent, boron-containing coupling agent, etc. Among them, silane coupling agent is the earliest coupling agent in research and application, and titanate coupling agent appeared in the late 1970s. It has a good coupling effect on many dry powders. The following will briefly introduce the coupling agents commonly used in production and their applications.
The reason why it is called a silane coupling agent is that 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 hydrolyzable hydrophilic group such as alkoxy, ethoxy and chlorine. The addition amount is usually about 1% of the filler.
So what is the selection principle of the coupling agent? Take a look at the introduction of titanate coupling agent manufacturers.
The titanate coupling agent manufacturer said that its structure is similar to that of titanate coupling agent. There are two active groups in the molecule, one of which can interact with the surface of the inorganic filler; the other will entangle with the resin molecule, resulting in Coupling between inorganic filler and matrix resin. It is light in color, non-toxic and easy to use. Its thermal stability is better than that of titanate coupling agent, and the price is only half of titanate coupling agent.
The dosage of aluminate coupling agent is generally 0.3% to 1.0% of the composite filler. For plastic hard products by injection or extrusion, it is about 1.0% of the filler, and for products formed by other processes, soft products and foamed products, it is about 0.3% to 0.5% of the filler. Aluminum hydroxide, magnesium hydroxide, silica and other high specific surface area fillers can be used in an amount of 1.0% ~ 1.3%
Zirconium coupling agent can not only promote the combination of inorganic and organic substances, but also improve the performance of filler system. Its characteristics are that it can significantly reduce the viscosity of the filler system, inhibit the interaction between the filler particles, and reduce the viscosity of the filler system, thereby improving the dispersion of the system and increasing the filling amount.
Zirconium coupling agent has good modification effect on calcium carbonate, silica, alumina, titania and clay. Mainly suitable for different polymer filling systems such as polyolefin, polyester, epoxy resin, nylon, polyurethane, synthetic rubber, etc.
Unsaturated organic acids and trivalent chromium atoms form coordination metal complexes. In FRP, it has a very good application effect.
The cost of organic chromium coupling agent is low, but the variety is single, and the application range and coupling effect are not as good as silane coupling agent and titanate coupling agent. The main reason is the toxicity of chromium ions and its pollution to the environment, which has led to the gradual reduction of the current dosage.
The aluminum-titanium composite coupling agent uses aluminum to replace part of the central atom of the coupling agent, which reduces the content of expensive titanium in the coupling agent and reduces the cost. It combines the characteristics of titanium and aluminum coupling agents, and its coupling effect is better than monotitanate, aluminate and their simple mixtures.