The price of natural rubber is high and fluctuates greatly, making it costly and difficult to control for rubber product manufacturers. Therefore, many manufacturers of natural rubber products fill a large amount of calcium carbonate in natural rubber to increase the volume of the product and reduce the cost of raw materials. When natural rubber is filled with calcium carbonate, sulfur vulcanization is more common. The mechanical properties of the rubber after vulcanization with a vulcanization system composed of different amounts of sulfur are quite different. Manufacturers need to choose a suitable vulcanization system for vulcanization according to the actual needs of natural rubber products.
1. The relationship between vulcanization system and vulcanizate properties
Sulfur is the most commonly used vulcanizing agent in the production of rubber products. Generally, the mass fraction of polysulfide bonds in the vulcanized rubber material 2YLYY32 will be greater than 70% in the common sulfur vulcanization system with a large amount of sulfur, and the tensile strength and tear of the vulcanized rubber The elongation is high but the heat-resistant oxygen aging performance is poor. The amount of accelerator in the semi-effective vulcanization system is usually greater than that of sulfur. The vulcanizate has excellent dynamic mechanical properties and good thermal and oxygen aging resistance.
2. Natural rubber chooses high-sulfur low-promoting rubber change law
In actual production, appropriately increasing the amount of accelerator and using coupling agents such as Si69 can significantly increase the tensile strength, tensile stress, hardness and tear strength of the natural rubber vulcanizate filled with calcium carbonate after aging. Increasing the amount of each compounding agent in the vulcanization system can increase the tensile strength, tensile stress, hardness and tear strength of the natural rubber vulcanizate; when the amount of sulfur is higher, the vulcanizate has poor aging resistance.
3. Methods to improve the comprehensive performance of natural rubber/calcium carbonate
When calcium carbonate filled natural rubber is vulcanized with sulfur, it is generally combined with accelerator M and accelerator DM. Adding a small amount of thiuram accelerator such as TMTD can further increase the effective cross-linking density of natural rubber, and the vulcanized rubber has better mechanical properties, especially suitable Production of light-colored natural rubber products. The combination of natural rubber/calcium carbonate compound uses accelerator CZ/DM, accelerator CZ/TMTD, and accelerator NS/TMTD to achieve fast vulcanization speed, high tensile strength, tear strength and aging resistance of vulcanizates.
A large amount of calcium carbonate filled in natural rubber is one of the ways to reduce the cost of natural rubber products, but improper use of calcium carbonate can easily cause the elasticity, strength, and viscosity of the natural rubber products to decrease, so it is necessary to control the amount of calcium carbonate reasonably. In actual production, to reduce the production cost of natural rubber products, product manufacturers can also use reclaimed rubber in an appropriate amount in the formula. The common ones are latex reclaimed rubber and tire reclaimed rubber, which can effectively reduce the cost of raw materials under the premise of ensuring product quality. There is little opportunity Edited to discuss with you in detail.
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