Different types and performance applications of coupling agents

In the process of plastic production, the most effective way to improve certain properties of plastics and reduce costs is to carry out filling modification. However, adding inorganic fillers to the resin will greatly reduce the solubility index, making it impossible to inject molding and resulting in poor apparent properties. Therefore, coupling agents are used during filling modification.

Coupling agents, also known as surface treatment agents in the industry, are actually organic substances that increase the affinity between inorganic fillers and organic polymers. Due to the hydrophilicity of most inorganic fillers, they are difficult to be compatible with polymers after mixing. Without coupling treatment, they can cause phase separation. Coupling agents will tightly connect fillers and polymers through physical and chemical interactions, thereby achieving good mechanical strength. On the other hand, inorganic fillers, whether treated with silane, titanate, or other coupling agents, will experience a decrease in the diameter of aggregated particles. For example, the aggregation particle size of precipitated calcium carbonate can be reduced by four fifths after treatment with advanced fatty acids, which can improve the dispersibility of the filler in the polymer and improve the flowability of the filler polymer system. These factors are beneficial for improving the mechanical properties, product quality, and processing performance of the product.

At present, coupling agents can be roughly divided into silane based, titanate based, chromium complex based, as well as other higher fatty acids, alcohols, esters, and so on. The invention history of silane coupling agents is relatively long, and they are still the main surface treatment agents for silicon containing inorganic materials such as glass fibers. Titanium ester coupling agent is a product from the 1970s, mainly used to treat non silicon inorganic fillers such as calcium and barium.