Natural rubber has excellent hand elasticity and high mechanical strength, and is the preferred raw material for rubber products. However, among all rubber varieties, natural rubber is the most prone to vulcanization and reversal, and the physical and mechanical properties of natural rubber products are serious. Impact; then what is the "vulcanization of the original", how to reduce the natural rubber vulcanization counter?
The vulcanization reverse is a phenomenon in which the vulcanized rubber crosslinked network is cracked due to excessive vulcanization temperature and excessive vulcanization time during the vulcanization of the rubber, resulting in a decrease in the physical and mechanical properties of the vulcanizate; from the vulcanization curve, the vulcanization temperature is too high. If the vulcanization time is too long or the vulcanized rubber is anaerobic aging, the vulcanization curve will decrease after the vulcanization. After the vulcanization is reversed, the tensile strength, the tensile stress and the hardness of the natural rubber will decrease, and the rubber surface will be sticky. phenomenon.
1. Adjust the vulcanization temperature
When using rubber to produce rubber products, the vulcanization temperature and the vulcanization time can be appropriately reduced to ensure that there are enough single sulfur bonds in the rubber network to improve the vulcanization reversion phenomenon. Studies have shown that the vulcanization temperature can be effectively prevented from vulcanization by reducing the vulcanization temperature below 140 °C during vulcanization of natural rubber.
2. Use with other types of rubber
Neoprene is a synthetic rubber produced by α-polymerization of chloroprene as a main raw material. It has excellent anti-reverse properties. It can replace some natural rubber in natural rubber products with neoprene, reducing the vulcanization of natural rubber. Anti-origin; the tendency of vulcanization in natural rubber can also be offset by the high cross-linking density of styrene-butadiene rubber or butadiene rubber. Therefore, adding a certain proportion of styrene-butadiene rubber and butadiene rubber to natural rubber can reduce the vulcanization of natural rubber. Anti-original effect; the combination of natural rubber and vinyl-structured butadiene rubber and trans-polyoctene rubber can also reduce the tendency of natural rubber to vulcanize the anti-origin.
3. Choose a suitable vulcanization system
The ratio of sulfur to accelerator in the effective vulcanization system and the semi-effective vulcanization system is high, or the sulfur donor is used instead of the elemental sulfur, which can make the number of monosulfide bonds and disulfide bonds with higher stability than the polysulfide bond in the crosslinked network of the rubber compound. Increase, thereby reducing the tendency of vulcanization anti-origin; therefore, the use of semi-effective vulcanization system and effective vulcanization system can give natural rubber better resistance to vulcanization; increasing the amount of zinc oxide in sulfur/sulfenamide vulcanization system can also reduce natural rubber The tendency of vulcanization is reversed; the thiuram vulcanization system and the peroxide vulcanization system can prevent vulcanization.
Reducing the natural rubber vulcanization system can also use related functional processing aids, which is not mentioned here. At present, the reclaimed rubber industry is developing rapidly. Many natural rubber products manufacturers have chosen to replace all or part of natural rubber with latex reclaimed rubber, which can reduce the cost of raw materials, improve the processing technology of rubber products, and reduce the vulcanization of rubber compounds. Latex recycled rubber raw materials have many sources, different production equipment, and the product quality varies greatly. Therefore, natural rubber products enterprises must polish their eyes when choosing latex reclaimed rubber, and choose to cooperate with the regular reclaimed rubber factory with stable product quality.