Element composition of vulcanizing agent

The typical representative is sulfur, which is the most basic and important vulcanizing agent in the rubber industry. The vulcanizing agent obtained by using the system of common sulfur - accelerant - activator has the advantages of good comprehensive performance and low cost. Therefore, in the rubber industry, especially in the tire industry still occupies a dominant position. Insoluble sulfur can avoid blowing sulfur, is not easy to burn, can be used for particularly important parts or products.

1, sulfur: Sulfur used in the rubber industry has sulfur powder, insoluble sulfur, colloidal sulfur, precipitated sulfur, sublimed sulfur, deacidified sulfur, do not crystallize sulfur. In 1839, Charles Goodyear, an American, mixed sulfur with rubber to produce a material with good performance, a landmark discovery that prompted people to begin in-depth research on the reaction mechanism, reaction heat history and reaction kinetics of sulfur vulcanized rubber. After more than 100 years of development, in 1979 Lautenschlaeger et al. used 2-methyl-2-pentene to simulate the vulcanization of natural rubber, and finally determined the terminal structure of the vulcanized rubber crosslinking bond, the external network structure and the main chain isomerization reaction product. As a rubber vulcanizing agent, sulfur has been developed for more than 100 years. Compared with other types, sulfur is cheap and the comprehensive performance of vulcanizing rubber is better, so it is still the leading vulcanizing agent in the international rubber industry, accounting for about 85% of the total composition of dozens of organic and inorganic vulcanizing agents. In order to meet the needs of rubber development, new products of sulfur are constantly emerging, such as the S80 GA F500 (yellow granular product) produced by MLPC International, a French company, which is the pre-dispersion of sulfur in acrylic derivative elastomers, in which sulfur content is 80%. The product has no dust and does not pollute the environment; Non-stick at room temperature, easier to feed and weigh.

Insoluble sulfur: When ordinary sulfur vulcanized rubber is parked, it is prone to spray frost and has a tendency to scorch, which greatly affects the performance of the final product. In order to make up for the shortage of Sulfur, people began to modify sulfur research, the successful example IS polymerized sulfur or Insoluble sulfur (Insoluble Sulfur), referred to as IS, the sulfur is insoluble in carbon disulfide linear polymer sulfur, is the μtype of sulfur. The average molecular weight of sulfur in this polymerized state is very large, and after continuous verification, it is generally believed that its molecular weight is 30,000 to 40,000. Insoluble sulfur is usually divided into oil-filled and unfilled types when used, and the vast majority (*99%) used in industry is oil-filled. Compared with ordinary sulfur, insoluble sulfur has the following advantages :(1) the adhesive will not spray during the storage period; (2) there is no migration in the compound (especially in the butadiene rubber and butyl rubber compound); (3) It can reduce the scorch phenomenon during mixing and storage; (4) is conducive to the adhesion of rubber and other materials; (5) It can shorten the curing time and reduce the amount of sulfur.

2, selenium, tellurium: natural rubber and styrene butadiene rubber second vulcanizing agent, can not be vulcanized when used alone.