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High temperature rapid vulcanization system for rubber

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With the automation and linkage of rubber industrial production, high temperature rapid vulcanization systems are widely used. Such as injection vulcanization, cable vulcanization, etc. The so-called high temperature vulcanization refers to vulcanization at 180-240 degrees. Generally, the vulcanization time is shortened by about half for every 10 degrees increase in the vulcanization temperature. The output is greatly improved, but the increase of vulcanization temperature will reduce the physical properties of the vulcanizate. This is related to the decrease of crosslink density during high temperature vulcanization. When the temperature is higher than 160 degrees, the decrease of crosslink density is the most obvious. Therefore, the vulcanization temperature is not as high as possible. How high the vulcanization temperature should be comprehensively combined; 1. The principle of high temperature vulcanization system coordination;

(1) Select heat-resistant rubber types. In order to reduce or eliminate the reversion of vulcanized rubber, rubber with low double bond content should be selected. The thermal stability of various rubbers is different, and the limit vulcanization temperature is also different. It is suitable for high-temperature vulcanization. There are rubber species, EPDM, IIR, NBR, SBR, etc.

(2) Adopt effective or semi-effective vulcanization system, because the content of polysulfide crosslinks in the CV vulcanization system is high, and the phenomenon of vulcanization reversion is easy to occur at high temperature. Therefore, CV is not suitable for high-temperature rapid vulcanization systems, and high-temperature rapid vulcanization systems are mostly used for effective EV and concomitant effective SEV vulcanization systems with high content of monosulfur and disulfide bonds. Its vulcanizate has good heat aging resistance. Generally, high-promoting low-sulfur and sulfur carrier vulcanization are used. The latter is best to use DTDM. The range of glue burning time and vulcanization characteristics is relatively wide, and it is easy to meet the processing requirements. TMTD is limited because of short glue burning time and serious frosting. Although EV and SEV are better than CV for high temperature vulcanization, they are not ideal. It is still impossible to completely solve the shortcomings of reversion and poor flexural resistance caused by high-temperature vulcanization, and a better solution should be found.

(3) For the special blending of vulcanizates, in order to keep the crosslinking density of vulcanizates unchanged at high temperature, it is possible to increase the amount of sulfur, the amount of accelerators or both at the same time, but the amount of increased sulfur will reduce the vulcanization effect, and It is better to increase the content of polysulfide crosslinks, and at the same time increase sulfur and accelerator, so that the vulcanization effect can be kept unchanged and the vulcanization effect can be improved. Widely used in tires. Synthetic rubber vulcanization system is less sensitive to temperature than NR, so it is very important to use NR and synthetic rubber together. After use, the system not only maintains the stability of crosslink density during high temperature vulcanization, but also maintains the best physical properties of vulcanizate. It is a rubber product. It is an effective method to use high temperature vulcanization, shorten the vulcanization time and improve production.

2. Other matching characteristics of high temperature vulcanization

 The high temperature vulcanization system requires fast vulcanization speed, small tendency to burn rubber, and no blooming phenomenon. Therefore, it is best to use heat-resistant rubber species, constant sulfur, and high accelerator methods. Higher requirements.

  In order to improve the vulcanization speed, it is necessary to use a sufficient amount of stearic acid to increase the solubility of zinc salts and improve the activation function of the system.

 In order to prevent the thermal aging effect during high temperature vulcanization and ensure the flatness of vulcanization, antioxidants are absolutely necessary in the high temperature vulcanization system, but they do not need to be too much. For example, adding 1 part of antioxidant D to TMTD/ZNO can be effective. Maintains stable crosslink density and vulcanization flatness. In order to prevent glue burning, a scorch inhibitor can be added to the system.

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