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Agent Dialkyl Dithiocarbamates Reduce The Use Of Vulcanization System When The Ecological Hazards Jun 01, 2017

Agent Dialkyl Dithiocarbamates Vulcanization is the basic process of the vulcanizate by the intergranular crosslinking of the raw rubber to form a three-dimensional network structure. Different vulcanization systems are suitable for different raw gums. 

    Despite the large number of documents on the vulcanization of elastomers, studies on rubber vulcanization are still being carried out in depth. The purpose of the study is to improve the mechanical properties and other properties of vulcanized rubber, simplify and improve the process,Agent Dialkyl Dithiocarbamates reduce the release of harmful substances in vulcanization and so on. In order to assess recent insights into vulcanization, the vulcanization system currently used is first described in detail.

    The traditional vulcanization system

    First, the unsaturated rubber is usually used in the following categories of vulcanization system. 

   1. Sulfur, organic disulfide and polysulfide, thiazole, diphenyl guanidine, zinc oxide and stearic acid-based curing agent. This is the most versatile vulcanization system. However, the vulcanized rubber produced by the heat-resistant aging performance is not high.

   2. Alkyl phenolic resin. 

   3. Polyhalides (such as hexachloroethane for polybutadiene rubber, styrene-butadiene rubber and nitrile rubber), hexachloro-p-xylene.

   4. Bifunctional reagents [such as quinones, diamines, azo and phenyl azo derivatives (for butyl rubber and ethylene propylene rubber), etc.]. 

   5. Bismaleimide, diacrylate. A bivalent metal acrylate (methacrylate), a prepolymer ether acrylate. 

   6. Organic peroxides for vulcanization of saturated rubber. 

    Second, saturated rubber vulcanization of different types of saturated rubber, you can use a different curing system. For example, when vulcanized ethylene propylene diene rubber is used, organic peroxides are used with unsaturated crosslinking agents such as triallyl isocyanurate (vulcanizing agent TAIC). 

    Third, the vulcanized silicone rubber can also use organic peroxides. Vinyl silicone rubber vulcanization can be in the catalyst (Pt) under the conditions of participation. 

    Fourth, halogen-containing rubber or functional groups containing rubber Polychloroprene rubber, chlorosulfonated polyethylene and chlorinated butyl rubber is the most commonly used chlorine-containing rubber. 

    Vulcanized neoprene is usually used as a combination of ZnO and MgO, with ethylene thiourea (NA-22), thiuram disulfide, di-o-tolyl dipeter (accelerator BG) and sulfur as vulcanization accelerator.

    Fifth, sulfide sulfonated polyethylene can be used when the following curing system.

   1. A combination of alumina, lead oxide and magnesium oxide, and magnesium oxide and pentaerythritol ester, vulcanized accelerator with tetradecane pentamethyl thiophane (accelerator TRA) and accelerator DM. 

   2. Six methyltetraamine and adipic acid and sebacate and magnesium oxide.

   3. Organic amine and epoxide effect of the product. 

   Six, the following system can be used for chlorinated butyl rubber vulcanization:

   1. The combination of zinc oxide with stearic acid, magnesium oxide, thiuram and benzothiazole disulfide;

   2. A combination of vinyl dithiourea and zinc oxide and magnesium oxide.

   3. The combination of polyhydroxymethyl phenol resin and zinc oxide.

   4. Zinc dialkyl dithiocarbamate.

   5. Hydroxyaromatic compounds (resorcinol, hydroquinone, etc.) (at room temperature).

    Seven, vulcanized carboxyl rubber often use metal oxides and peroxide, polyols, diamines and polyamines, epoxides, diisocyanates and polyisocyanates.

     8, vulcanization of amine-based rubber is often used to add zinc oxide sulfur vulcanization system, halogen-containing organic and epoxy resin.

    Nickel, vulcanized rubber containing nitrile (such as MnO2, Sb2O5) sulfide (such as CuS) and the addition of sulfur polyamine (for acrylic rubber).

    In the absence of a vulcanizing agent, a reaction occurs between functional groups having reactivity in the polymer. It is also possible to generate a chemical crosslinking bond network in the elastomer. For example, at high temperatures, PVC and nitrile rubber and plastic with that there is such a situation. 

    Non - traditional vulcanization system

    Over the past decade, the main research content is the vulcanization process itself and vulcanized rubber products in the course of the ecological problems and improve the curing process, reduce the scorch and return to the original tendency to promote cold vulcanization and so on. To prevent the vulcanizing agent,Agent Dialkyl Dithiocarbamates especially sulfur in the finished product in the frost has also given some attention. By selecting the appropriate curing system and curing conditions in improving the performance of vulcanized rubber and products have also made some achievements.

    Reduce the use of vulcanization system when the ecological hazards

    Unsaturated rubber vulcanization system usually contain sulfur, so is currently taking a series of measures to prevent sulfur in the process of weighing and so on, such as the use of granulation process.

    Usually with sulfur and dicyclopentadiene, styrene and its oligomers of the copolymer to eliminate sulfur blowing cream. It has also been suggested that the combination of sulfur and polymer resin, sulfur in the ring hydrocarbon oil in the solution, sulfur oligomer butadiene, sulfur and 5-ethylene - bicyclo [9.2.1] hept-2-ene And tetrahydroindene and the like. The addition of N-trichloromethylisulfo-p-aminobenzenesulfonate to sulfur vulcanizate reduces the frosting. The copolymers of ethylene and α-olefins, α-olefin rubbers and ethylene-propylene rubbers can be vulcanized with bismaleimide derivatives containing Cl, S or SO2 groups without sulfur vulcanization.

    The ecological hazards of nitrosoamines are well known. Thus, diamine-based promoters are dangerous due to the generation of volatile nitrosamines. The least dangerous is dibenzyl dithiocarbamate and dibenzyl thiuram disulfide. Sulfenamides and tetramethylthiuram disulfide and other lower alkyl thiuram agents can be used in a limited amount (0.4-0.5%). The accelerator DZ (N, N'-dicyclohexyl-2-benzothiazole sulfenamide) is often used for tire compounds, and disulfide and dibenzyl thiuram bismaleimide And use. No nitrous oxide derivatives containing nitrogen atoms and a small amount of commonly used accelerator combination does not produce nitrosoamine. (C1-5) oxathiyltrisulfide with N-trichloromethylsulfonylphenylsulfonamide and benzothiazole disulfide (accelerator DM) and dibenzyl dithioamino Zinc formate and the like as the accelerator does not produce nitrosoamine. The use of vitamin C and vitamin E additives can reduce the amount of nitrosoamine produced in the general vulcanization system. From an ecological point of view, it is desirable to use an accelerator predominantly substituted with 1,1'-dithiobis (4-methylpiperazine) and other piperazine derivatives as an accelerator, And urea, and the use of a mixture containing 2-15% polythiazole, 15-50% bismaleimide,Agent Dialkyl Dithiocarbamates 15-45% sulfenamide and 20-55% sulfur can reduce the formation of nitrosylamine The It is recommended to use alkyl dithiophosphate as a vulcanization accelerator for EPDM, where nitroamines are not produced. Pretreatment of filler with ZnO with ammonia or n-amine prevents the formation of nitrosylamine. It is also possible to prevent the formation of nitrosoamine by adding a small amount of CaO, Ca (OH) 2 and Ba (OH) 2 to the sulfide of polybutadiene lead styrene-butadiene rubber.