The powder having a certain fineness obtained by pulverizing the crosslinked rubber in the waste rubber product (mainly waste tire) by mechanical pulverization or freeze pulverization is a vulcanized rubber powder, and the vulcanized rubber powder is mixed in a rubber product such as rubber. Tires and rubber sheets can reduce the cost of raw materials for rubber products and recycle waste rubber. In the actual processing process, the unreasonable use of vulcanized rubber powder will cause the mechanical properties of rubber products to decline, so it is necessary to take certain measures to improve.
1. Refined rubber powder
When the vulcanized rubber powder is directly added to the rubber product, there is a clear interface between the rubber powder and the matrigel, which causes local stress concentration of the vulcanized rubber, and the tensile strength, tear strength and flexural resistance of the rubber product are reduced. The vulcanized rubber powder can be placed on the open mill for a certain period of time to reduce the activity of the vulcanized rubber powder and alleviate the negative impact of the vulcanized rubber powder on the mechanical properties of the rubber product.
2. Adjust the vulcanization system
As the most traditional vulcanizing agent in the rubber products industry, sulphur is still widely used in the production of rubber products. The vulcanized rubber powder is used in the selection of sulfur vulcanized rubber products. When vulcanization, the sulfur will move from the rubber phase to the rubber powder. The transfer leads to a decrease in the sulfur concentration at the interface between the rubber phase and the rubber powder and the rubber, a decrease in the crosslinking bond, and a decrease in the average crosslinking density at the interface between the rubber and the rubber powder, resulting in a decrease in the mechanical properties of the rubber after vulcanization; In the formulation of rubber products containing vulcanized rubber powder, increase the amount of sulfur, increase the sulfur concentration in the rubber phase or use a fast vulcanization accelerator to improve the mechanical strength of the rubber product; replace the sulfur with a peroxide and adjust the vulcanizing agent appropriately, The amount of accelerator can also increase the mechanical strength of the vulcanizate containing the rubber powder.
3. Add special compounding agent
Hexamethylenetetramine (accelerator H) is a slow-acting high-speed accelerator, which is easy to disperse in the rubber compound. The initial vulcanization is slow but the effect is good. The combination with resorcin or modified phenolic resin can enhance the adhesion. To alleviate the effect of vulcanized rubber powder on the tensile strength of rubber products, and to improve the tear strength of rubber products to a certain extent, generally resorcinol and hexamethylenetetramine are added during the rubber powder mastication, and the ratio of the two is 4:3 works better.
The multifunctional auxiliary agent PA can be used as a surfactant, dispersant, accelerator and internal mold release agent in rubber products, which can increase the vulcanization speed of the rubber compound and improve the mechanical properties of the vulcanizate; the vulcanized rubber powder in the rubber product can be combined with the PA. Synergistic effect, thereby improving the tear strength, wear resistance, flex resistance and the like of rubber products containing vulcanized rubber powder: for example, when a rubber conveyor belt or a rubber tire is mixed with an appropriate amount of vulcanized rubber powder to reduce the cost, the use of PA can be significantly improved. Mechanical properties of the product and improved processing and surface gloss.
Appropriate use of vulcanized rubber powder, rational use of vulcanized rubber powder, master the use of vulcanized rubber powder and take corresponding measures, rubber products manufacturers can reduce the production cost of rubber products while ensuring the mechanical strength of rubber products.