Role and Classification of Plastisols in Rubber
Plasticizer is a substance that can enhance the plasticizing effect of raw rubber and shorten the plasticizing time through chemical action.
1.Traditional classification
Plasticizer can be divided into physical plasticizer and chemical plasticizer. Physical plasticizers include fatty acids and fatty acid derivatives, zinc salts of unsaturated fatty acids, esters, waxes; chemical plasticizers include pentachlorothiophenol, aryl disulfides, organosulfonates.
2.Classification according to the temperature range of use
According to the different temperatures of the plasticizer, it can be divided into low-temperature plasticizer, such as dimethylphenyl thiophenol, zinc salt of pentachlorothiophenol and zinc salt of 2-benzamide thiophenol, etc., which are suitable for open-end refining; high-temperature plasticizer, such as dimethylphenyl disulfide, 2, 2'-diphenyl disulfide of dibenzamide base, etc., which are suitable for compacting refining; and mixed-type plasticizer, such as accelerator M, DM, etc., which are effective both in the low temperature and high temperature, and are suitable for both open-end and open-end refining. Mixed plasticizers, such as accelerators M, DM, etc., are effective at both low and high temperatures, and are suitable for both open and close kneaders.
3. Classification according to the mechanism of action
(1) Acceptance-type plasticizer
Mainly phenylthiophenol, pentachlorothiophenol, etc., which are low-temperature plasticizer. In low-temperature plasticizing, can make the chain of rubber molecules free radical stabilization and generate shorter molecules. These compounds itself is a free radical acceptor, can react with free radicals, so that the free radicals produce chain suspension.
(2) Initiating plasticizer
Mainly benzoyl peroxide, azodiisobutyl cyanide, etc., is a high-temperature plasticizer. Its role is mainly to decompose the extremely unstable free radicals at high temperatures, prompting the rubber molecules to generate free radicals, which in turn triggers the rubber molecular chain to produce oxidative chain reaction process, resulting in rubber molecular chain breakage. Due to the presence of rubber free radicals, it will be further reacted in the air according to the automatic oxidation chain reaction process, until the final decomposition of the relative molecular mass of small compounds.
(3) Mixed Plastisols
Mixed-type plastolytic agent is also known as chain transfer-type plastolytic agent. There are mainly accelerator M, accelerator DM and 2,2-diphenylformamide diphenyl disulfide. This kind of plastolytic agent can not only play the role of free radical receiver in low-temperature plasticizing, but also decompose free radicals in high-temperature plasticizing, triggering the oxidation chain reaction of rubber molecules.