Di(2,4-dichlorobenzoyl) peroxide and 2,5-Dimethyl-2,5-Di(tert-butyl peroxide) hexane are the two most used vulcanizing agents for HCR silicone rubber molding. usually Di(2,4-dichlorobenzoyl) peroxide contains halogen and can be vulcanized below 266°F, generally used in the extrusion molding process; 2,5-Dimethyl-2,5-Di(tert-butyl peroxide) hexane does not contain halogen and needs to be vulcanized above 266°F, generally used in the molding process.
1. Di(2,4-dichlorobenzoyl) peroxide
Molecular weight: 380.0
Theoretical active oxygen content: 4.21%
CAS No.： 133-14-2
Di(2,4-dichlorobenzoyl) peroxide is a transparent paste with a slight taste, which is a general-purpose vulcanizing agent with low decomposition temperature and fast decomposition speed, and is a good vulcanizing agent for HCR silicone rubber, suitable for the production of mid-grade silicone rubber products and products with high transparency requirements. Vulcanization temperature is 212-248 °F, the recommended dosage is 0.8-1.2%, and the vulcanization time is about 4-7 minutes. The vulcanization process will decompose toxic substances 2,4-dichlorobenzoic acid and 2,4-dichlorobenzene, and will affect the heat resistance of silicone products. Since carbon black interferes with the vulcanization of Di(2,4-dichlorobenzoyl) peroxide, it cannot be used to mold silicone rubber materials containing carbon black.
2. 2,5-Dimethyl-2,5-Di(tert-butyl peroxide)hexane
Molecular formula: C16H34O4
Molecular weight: 290.44
Theoretical reactive oxygen content: 11.02%
2,5-Dimethyl-2,5-Di(tert-butyl peroxide)hexane is abbreviated as DBPH, which is light yellow liquid and paste and creamy white powder with high decomposition temperature and good scorch performance. When DBPH is used, the silica gel has lower compression deformation and higher elongation. It is generally used as vulcanizing agent for HCR silicone raw material molding process. Vulcanization temperature 347°F, recommended ratio 0.8%-1.2% Vulcanization time about 5 minutes. It does not produce products with carboxyl groups when decomposed, so it does not affect the thermal stability of silicone products.
1. polymer cross-linking agent: is an organic peroxide cross-linking agent that can be widely applied to a variety of polymers, especially suitable for polyethylene (LDPE, HDPE), ethylene / vinyl acetate copolymer polymerization cross-linking agent, cross-linking temperature of 338 °F or more, below 284 °F is not cross-linking reaction. The dosage is usually 0.5%-3% (W / W), in some materials not easy to cross-linking reaction dosage is generally 1%-5%.
2. vinyl silicone rubber high-temperature vulcanizing agent: with this vulcanizing agent for vulcanization of silicone rubber with high tensile strength, hardness and other advantages. Meet the U.S. FDA approval, can be used in reusable rubber products.
3. Polypropylene degradation agent: degradation temperature is 392-428°F, the dosage is 0.01%-0.1%. Can be made into low molecular weight, narrow distribution of high melt index rheological polypropylene, can be used as high-speed spinning material, coating material, film material and casting plastic important initiator, is the production of cooling masterbatch of choice for raw materials.
4. unsaturated polyester curing agent.