Natural rubber is used in the production of various rubber products such as tires, inner tubes, rubber tubes, rubber tapes, sponge rubber, sealing products, etc. When using natural rubber to produce rubber products, the use of softening and plasticizing system can improve the processing performance of the rubber, promote the uniform dispersion of the compounding agent, increase the plasticity, fluidity and adhesion of the rubber, and improve the calendering, extrusion, molding and other processes. The compounding agents commonly used in the softening and plasticizing system of natural rubber products are mainly divided into two categories: physical plasticizers and chemical plasticizers.
1. Key points of common physical plasticizers for natural rubber products
The purpose of using physical plasticizers in natural rubber is to obtain good process properties, such as viscosity and softness, to provide a better basis for subsequent mixing, calendering, extrusion molding and other process operations, and to adjust the hardness of natural rubber. When selecting softening plasticizer for natural rubber products, it is necessary to fully consider the influence of blending agent on the physical and mechanical properties of rubber and the application of softening agent on the color of rubber. In actual production, the softening plasticizers commonly used for natural rubber include pine tar and petroleum series softeners.
In general, the amount of pine tar in the softening and plasticizing system of natural rubber product formula is controlled at 4-5 parts, and the amount of petroleum softener is controlled at 5-15 parts.
2. Key points of common chemical plasticizers for natural rubber products
Chemical plasticizer, namely chemical plasticizer, can significantly improve the plasticity and plasticizing efficiency of rubber plasticizing, and shorten the plasticizing time by about 1/3. The smoke rubber 2SLYY215 and crepe rubber in natural rubber products have high Mooney viscosity and are difficult to be molded. Adding chemical plasticizer can improve the plasticizing effect of raw rubber, shorten the time and improve the plasticizing efficiency. At present, the natural rubber molding process is mostly carried out in the open mixer and the internal mixer. When the open mixer is used for molding natural rubber, the chemical plasticizer SJ-103 can be used; When mixing natural rubber with internal mixer, plasticizers SJ-103 and 12-I can be used.
When chemical plasticizer is used in natural rubber softening and plasticizing system, the amount of chemical plasticizer is generally controlled among 0.1-0.3 phr.
At present, many rubber products with natural rubber as the main raw material will use recycled rubber appropriately, such as latex recycled rubber, tire recycled rubber, etc. The addition of recycled rubber can improve the processing technology of pure rubber to a certain extent, such as plasticity and fluidity. When using natural rubber to produce rubber products, the rubber product manufacturer should not only reasonably design the softening and plasticizing system, but also carefully select the curing system, reinforcing and filling system, anti-aging system and other compounding systems. Later, the editor will continue to share rubber technology issues with you.
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