Natural rubber is processed by solidification and drying of natural latex. It has high mechanical strength and good elasticity. It can be used to produce various high-elastic rubber products with high elasticity, high strength and high wear resistance. Sulfur is the most commonly used natural rubber. The vulcanizing agent, the vulcanized natural rubber can maintain high mechanical strength; but the experiment shows that when the natural rubber is only vulcanized with sulfur, it takes 5 hours to reach the optimum vulcanization degree, then how to accelerate the vulcanization of the natural rubber sulfur vulcanization system What about speed?
1. Use zinc oxide
Zinc oxide is a white hexagonal crystal or powder. It is an amphoteric oxide and is an active agent commonly used in the production of rubber products. It has thiazole accelerators, sulfenamide accelerators, anthraquinone accelerators and thiuram accelerators. Activation, adding appropriate amount of zinc oxide in the natural rubber vulcanization system with sulfur as vulcanizing agent can significantly accelerate the vulcanization rate of the rubber compound and increase the crosslink density of the natural rubber vulcanizate. It is understood that the addition of an appropriate amount of zinc oxide to the natural rubber with sulfur as a vulcanizing agent can shorten the time for the optimum vulcanization of the rubber to 4 hours.
2. Use accelerator M
Promoter M is a commonly used variety of thiazole accelerators. It has a low critical temperature during vulcanization and is a general-purpose overspeed accelerator. It can rapidly vulcanize rubber when it is combined with sulfur in natural rubber, thereby accelerating the vulcanization rate of natural rubber.
3. Use stearic acid
Stearic acid is a vulcanization active agent widely used in the production of natural rubber products. It can play an acid-type activation role in natural rubber and can form a soluble zinc salt with zinc oxide, thereby increasing the activation ability of zinc oxide to enhance the accelerator, thereby accelerating The vulcanization rate of natural rubber vulcanized using a sulfur vulcanization system. The natural rubber is sulfur vulcanized, and the appropriate amount of zinc oxide, accelerator M and stearic acid are used together, and the natural rubber can complete the vulcanization process in 20-30 minutes.
In actual production, the quality and dosage of zinc oxide, accelerator M and stearic acid should be strictly controlled. The lead, cadmium, iron, copper and other substances contained in zinc oxide will hinder the activation of zinc oxide on the accelerator and affect the resistance of the product. The aging performance should reduce the content of such impurities in zinc oxide, especially lead and cadmium; if the amount of stearic acid is too much, it will spray out the surface of the rubber compound, which will affect the adhesion of the semi-finished products and delay the vulcanization, which should be controlled.
The combination of various compounding agents in the natural rubber sulfur vulcanization system is the main reason that affects the vulcanization rate of the rubber compound. When the natural rubber is vulcanized with sulfur, it can also choose sulfur/accelerator DM, sulfur/accelerator CZ, sulfur/accelerator DM/ The accelerator D and the like cooperate with the system. Increasing the vulcanization efficiency of sulfur vulcanized natural rubber products can also be achieved by appropriately increasing the vulcanization temperature, vulcanization pressure, etc., and Xiaobian will not elaborate.