As we all know, MBS / NOBS, TMTD, DTDM and other accelerators in the intermediate reaction of sulfide will decompose nitrosamine carcinogens, how to choose alternatives? Want to adopt environmentally-friendly curing system to deal with the EU, see below!
Sulfide vulcanization accelerator commonly used in tire production are sulfenamide accelerator and thiazole accelerator. Thiazole accelerator non-toxic, but its scorch time is short, the vulcanization speed of the characteristics of the decision in the tire production as a secondary accelerator mainly appear, the actual amount is less, the main application of accelerator M and DM.
Sulfonamide accelerator easy to process and safe, fast curing speed and high physical and mechanical properties occupy the top of the tire production accelerator varieties, commonly used accelerator including MBS / NOBS, TBBS / NS, CBS / CZ, DCBS / DZ.
MBS produce nitrosamines, tire manufacturers in western developed countries and regions have stopped using the accelerator, the domestic is still using this product. Tire often add a small amount of thiuram accelerator as a second accelerator, the commonly used species is tetramethylthiuram disulfide TMTD, the product can produce nitrosamines. A common species used in sulfur donors is dithiodorphorphine DTDM, which also produces nitrosamines.
The above three types of raw materials can produce nitrosamines harmful to human health, the EU promulgated the REACH regulation has clearly stipulated that the products exported to the EU ban the use of the above raw materials. The following are some of the available alternative environmentally friendly alternative for reference:
1 can be used instead of TBBS / NS, but need to add more anti-scorching agent CTP;
2. Instead of TBSI, N-tert-butyl-bis (2-benzothiazole) sulfenamide scorch between NOBS and DZ, the price is relatively low. TBSI chemical name Nt-butyl-bis (2-benzothiazole) accelerator, abbreviated as TBSI, is also a sulfenamide accelerator. This product is used in plastic materials to extend the scorch time and slow cure rate characteristics. TBSI compared with TBBS, due to its large molecular weight, good thermal stability, higher melting point than TBSS 30 ℃, with a long scorch time, curing speed and so on. At present, TBSS is often used with scorch inhibitor CTP, TBSI can replace TBBS + CTP alone. In addition TBSI also has a water-stable, easy to store; significantly improve the vulcanization of natural rubber rubber vulcanization reducibility; in the rubber and wire bonding compounds perform well; can be used for all the elastomer, especially for the fight against the reduction requirements High thick products and so on.
3. CBS can be used instead of, will not produce N-nitrosamines accelerator, it is equivalent to replace NOBS, the vulcanization rate is quite. Scorch slightly better performance than NOBS and CZ, vulcanized rubber and NOBS physical properties are also quite widely used in urban tires and other rubber products.
4. Can be used instead of XT580, N-fatty benzothiazole sulfenamide, its performance completely NOBS equivalent, but also non-toxic, the price is lower than NOBS.
Accelerator MBS / NOBS:
1. TBZTD (tetrabenzylthiuram disulfide) can be used instead, with better scorch safety and anti-reversion; TBZTD name is tetrabenzylthiuram disulfide, abbreviated as TBZTD. This product is a newly developed thiuram accelerant that can replace TMTD (thiuram tetramethyldisulfide) and can be used as the main accelerator or co-accelerator for rapid vulcanization of natural rubber, nitrile rubber and styrene-butadiene rubber. Processing is more secure and has a longer scorch time than TMTD. Due to its large molecular weight, high melting point and difficult decomposition, TBZTD does not produce nitrosamines. TBZTD, in particular, has a slightly lower cure rate than TMTD. Its other physical properties are almost the same as that of TMTD. It has become a promising thiochlamid Vulcanization accelerator new varieties.
Curing agent DTDM:
1. DTDC (N, N'-dithio caprolactam) can be used instead of white crystalline form, the melting point of 120 ~ 122 ℃, the active sulfur mass fraction greater than 0 19. With its equivalent replacement curing agent DTDM, without changing the formula and process rubber. Like the vulcanizing agent DTDM, the vulcanizing agent DTDC can replace all or part of the sulfur to form an effective or semi-effective vulcanization system. Since the vulcanizing agent DTDC can release active sulfur under normal vulcanization conditions and form sulfur monosulfide and disulfide bonds between the rubber molecules with added sulfur, the rubber vulcanization network structure can impart excellent heat resistance and compression resistance to vulcanizates Sexual and high set stress. Curing agent DTDC also has the characteristics of non-blooming, scorching safety, curing speed, is the tire and other large model rubber products, heat-resistant rubber products, health rubber products and color rubber products, the best curing agent.
2. Alkyl phenol disulfide (VULTAC-5) can be used instead of, alkyl phenol disulfide, suitable for different polar rubber system and white sidewall.
3. Instead of using aliphatic polysulfides.