1. Thiourea system, 2. Peroxide system, 3. Thiadiazole system, 4. Triazole dimercapto amine salt system.
First, thiourea system was used earlier in CPE vulcanization system, among which Na-22 was the most effective one. However, Na-22 had slow vulcanization speed, poor aging performance, high compression permanent deformation, and Na-22 was a serious carcinogen, which produced unpleasant odor during vulcanization and had been restricted to use abroad.
2. At present, the mature application of CM vulcanization system is peroxide vulcanization system, which has faster vulcanization speed, better physical properties and smaller compression permanent deformation. Peroxide system can be used in the production of adhesive tape. The product has good physical properties, heat resistance and oil resistance. The physical and mechanical properties and heat resistance of the system can be obviously improved by adding cross-linking aids such as TAIC, TAC, TMPTM and HVA-2. Because peroxide is cross-linked by free radical reaction, some acidic fillers will affect the formation of free radicals, so this kind of fillers should not be used. However, peroxide is not suitable for low pressure, Moldless vulcanization, high process requirements, it is difficult to apply in most rubber products process.
3. Eata MixTCHC is a special vulcanizing agent for CPE, which is non-toxic. TCHC can use cheap aromatic oil as plasticizer, and its vulcanizate has excellent properties. The activity of MgO has little effect on the physical properties and aging properties of TCHC vulcanizates. Ultrafine Mg(OH)2 as acid absorbent is comparable to high-activity MgO with iodine absorption value 150. It can replace expensive imported high-activity MgO and greatly reduce the manufacturing cost.
The cost of application is much lower than that of thiadiazole system abroad. It can be applied to various vulcanization processes, including low temperature, die-less, pressure-less and low pressure vulcanization. This system has fast vulcanization speed, excellent physical properties, low compression set, good heat resistance, oxygen resistance, ozone aging and oil resistance. It is also an effective co-crosslinking system of CPE and diene rubber. It has been successfully applied in hose industry. TCHC vulcanization rate is slower than peroxide, but it can be vulcanized at lower temperature and without pressure and mould, and the vulcanizate has excellent properties.
Thiadiazole system mainly consists of crosslinking agent and accelerator. The main crosslinking agents are ECHO.A, ECHO.TDD, PT75 and TDDS. The main promoters are Vanax 808, Eata AccelDH, NC, Accel 903 and BF. It is a kind of promising auxiliaries.
4. Triazole dimercapto amine salt system.
Triazole dimercapto amine salt vulcanizer is a single substance which integrates the effective groups of thiadiazole vulcanizer and accelerator (n-butyraldehyde and aniline condensate). It overcomes the irregular distribution of bonds after thiadiazole and accelerator cross-linking rubber, and makes the rubber cross-linking become a stable structure. Compared with thiadiazole system, the salt also changed the PH value of the system from strong acidity to neutrality due to the introduction of special groups, which changed the adverse effects of acidic fillers on the system and made the rubber more chemically active when crosslinking. Therefore, the physical and chemical properties of CPE rubber crosslinked by this system have been improved qualitatively. Aromatic oil, magnesium oxide and magnesium hydroxide can be used as raw materials, suitable for low-temperature, pressure-free and low-pressure vulcanization process conditions, fast vulcanization speed, faster than thiadiazole, less dosage (2 phr), unit price concessions, no decomposition within the vulcanization temperature, no odor, environmental protection and non-toxic.