In the rubber industry, calcium carbonate is the third largest inorganic filler and reinforcing agent after carbon black and white carbon black. In the past two years, in order to reduce carbon emissions and environmental problems caused by excessive release of carbon black, the application of calcium carbonate in rubber has received more attention.
What is the role of calcium carbonate in rubber?
As a filler, calcium carbonate can increase the volume of rubber, reduce the cost of products, and improve the processing performance without significantly affecting the performance of rubber products. As a reinforcing agent, calcium carbonate can greatly improve the wear resistance, tear strength, tensile strength, modulus, swelling resistance and other properties of vulcanized rubber.
So what kind of calcium carbonate is a filler for rubber, and what kind of calcium carbonate is a reinforcing agent for rubber? Among them, there is no strict or standard division yet.
Light calcium is a filler extender commonly used in the rubber industry. It has a large filling amount, is easy to extrude, has good gloss, low hardness, and high elongation. Its mechanical properties can exceed that of clay and reach the level of semi-soft carbon black. Active nano-calcium can not only be used as a filler for rubber compounds, but also has high reinforcing properties, which can improve the wear resistance, tear resistance, modulus and other properties of rubber, and can also reduce production costs. Heavy calcium has excellent filling performance in rubber, easy to mix and disperse, and the compounding amount can reach 100%~250% of the rubber content. It is the main low-cost filling material in the rubber industry.
How to modify calcium carbonate for rubber?
In recent years, powder surface modification technology has become one of the hot technologies that people pay attention to. Among them, surface coating modification is an important kind of surface modification technology. Coating, also known as coating or coating, is a method of coating the surface of mineral particles with inorganic or organic substances to achieve modification.
The surface coating of calcium carbonate powder is also to introduce a coating layer on the surface according to the need, so that the modified calcium carbonate can be regarded as a composite powder composed of “core layer” and “shell layer”. By coating a layer of covering layer with different chemical composition (such as carbon black) on the surface of calcium carbonate, it can have good dispersion and compatibility with rubber. Different powder coating modification processes can improve its thermal, mechanical and chemical stability, change its optical, magnetic, electrical, catalytic, hydrophilic, hydrophobic and sintering characteristics, and improve its corrosion resistance, durability and usability. Lifespan etc.