Zinc oxide is an oxide of zinc, widely used in plastics, rubber, lubricants, ointments, food and other industries, which in the rubber products industry as a large amount of the third largest category of rubber raw materials - reclaimed rubber, its processing The process can not be separated from zinc oxide; zinc oxide in the production of recycled rubber products is a multi-functional additives, different recycled rubber products have different roles.
In the production of white light-colored rubber products using white latex reclaimed rubber as raw material, zinc oxide can be used as a colorant and a filler to adjust the color of the rubber products and change the performance of the reclaimed rubber materials. In transparent and translucent reclaimed rubber products , Zinc oxide can be used as an activator for the vulcanization system to activate the vulcanization system to strengthen the vulcanization process and shorten the vulcanization time. The reclaimed rubber used in automobile tires can be used as a reinforcing agent to improve the wear resistance and the anti-aging performance of the tire. In short, Many recycled rubber products require zinc oxide in the production, but the role of zinc oxide is not necessarily the same.
In addition, zinc oxide in the reclaimed rubber product formulations can also be used as a vulcanization accelerator to shorten the curing time, speed up the vulcanization rate and improve the cure efficiency of the vulcanization system; as an oxidant to improve the vulcanization system regeneration rubber products accelerator activity and reduce the amount of accelerator, Shorten the curing cycle; zinc oxide in recycled rubber products can also be used as thermal agents and heat capacity agent.
However, the most important use of zinc oxide in reclaimed rubber products is also used as an activator to enhance the promoter activity. This is because the zinc oxide used in the reclaimed rubber compound reacts with the accelerator in the vulcanization system to produce a zinc salt complex which contains an empty orbital 2n2 + particle polarizability apron which can promote the sulfur ring Molecular cracking, improve the curing rubber products efficiency.
Zinc oxide in reclaimed rubber products is commonly used with stearic acid for two main reasons:
a. Zinc oxide and the reclaimed rubber are all positively charged in the inner molecular band. So-called same-sex exclusion, zinc oxide is difficult to disperse in the rubber. When zinc oxide and stearic acid are used in combination, Zinc stearate generates zinc acid, can improve the solubility of zinc oxide in the compound, can react with the accelerator to form a good solubility complex, the activation of the entire curing system.
b. Zinc oxide and stearic acid together form a zinc salt in the compound. The zinc salt can be integrated with the crosslinks to protect the weak bonds in the reclaimed rubber molecules and promote the production of short Cross-linking and then add a new cross-linking, thereby increasing the crosslinking density of recycled rubber, rubber products to improve the fixed stress and hardness and other indicators.
Taking 100 parts of reclaimed rubber as an example, in actual production, 2-3 parts of zinc oxide can be added to reclaimed rubber reclaimed rubber products, about 4 parts of zinc oxide can be used in reclaimed rubber products, and butyl rubber reclaimed rubber products can be used Add about 5 parts of zinc oxide: usually 2-2.5 parts of zinc oxide, need to use about 1.5 parts and about stearic acid, to improve reclaimed rubber products processing performance, physical properties and curing efficiency, but different types of reclaimed rubber products The amount of zinc oxide also need to be properly adjusted.