Natural latex reclaimed rubber is processed from waste natural rubber, waste latex and its products as raw materials, with the basic performance characteristics of natural rubber, high strength, good elasticity and small specific gravity, which is an ideal raw material for replacing high-priced natural rubber to produce natural rubber products. When using latex reclaimed rubber to replace natural rubber production products, reasonable design of rubber formula can improve the comprehensive performance of reclaimed rubber products, improve processing technology, and reduce more costs.
1. Design of natural latex recycled rubber vulcanization system
(1) Sulfur vulcanization system
Sulfur vulcanization system can be divided into ordinary sulfur vulcanization system (high sulfur and low promotion system), effective sulfur vulcanization system (high sulfur low promotion and sulfur-free combined system) and semi-effective sulfurization system. When the latex reclaimed rubber adopts the ordinary sulfur vulcanization system, the vulcanized rubber has the characteristics of high strength, good elasticity and high wear resistance, but the aging resistance of the vulcanized rubber is poor. The natural reclaimed rubber vulcanized with an effective vulcanization system has good heat aging resistance, but the vulcanized rubber has low mechanical strength and is easy to scorch. The semi-effective vulcanization system is among the sulfur vulcanization system and the effective sulfurization system.
When using latex reclaimed rubber to produce rubber products with high requirements for physical and mechanical properties, such as tensile strength, ordinary sulfur vulcanization system is mostly used; When latex reclaimed rubber products require good high temperature resistance and aging resistance, it is recommended to use an effective sulfur vulcanization system.
(2) Peroxide vulcanization system
Latex reclaimed rubber or natural rubber/latex reclaimed rubber can be vulcanized with organic peroxide, the most commonly used vulcanizing agent is cumene peroxide (DCP), vulcanized rubber has good thermal stability and excellent high temperature aging resistance, small creep, small compression set, good dynamic performance; However, the vulcanization rate of the rubber is slow, easy to scorch, and the physical and mechanical strength of the vulcanized rubber is low.
2. Design of natural latex recycled rubber reinforcement filling system
The main function of the rubber reinforcement filling system is to improve the physical and mechanical properties of rubber, improve the processing technology and reduce the cost. In the production of latex recycled rubber products, the dosage of rubber reinforcing agent and filler needs to be determined according to the performance requirements of the product and the glue content index.
When using latex reclaimed rubber to produce rubber products with high requirements for wear resistance, ultra-wear-resistant carbon black, medium super wear-resistant carbon black and high wear-resistant furnace black can be used; When rubber products have high requirements for tear resistance, it is recommended to use groove carbon black or modified furnace carbon black; The use of fast-pressing furnace black, general-purpose furnace black, semi-reinforcing carbon black, etc., can improve the elasticity and processing performance of latex recycled rubber products.
When natural reclaimed rubber is used to produce light-colored and colored rubber products, silica and ultra-fine activated calcium carbonate can be used as reinforcing agents; When using silica, you can add an appropriate amount of organic active agents diethylene glycol, glycerol, triethanolamine, polyethylene glycol, etc. (5%-10% of silica dosage) to adjust the vulcanization rate.
3. Design of natural latex recycled rubber softening and plasticizing system
The main function of the compounding agent of the softening plasticizing system is to improve the processing process performance of the rubber compound, such as viscosity and softness, adjust the hardness of the rubber compound, and facilitate the process operations such as mixing, calendering, and extrusion molding. The softening plasticizers commonly used in latex reclaimed rubber products E4LYY64 pine tar and petroleum softeners; When selecting a softener, it is necessary to fully consider the influence of softening plasticizer on the physical and mechanical properties of the rubber compound and the color of the rubber, especially when using latex reclaimed rubber to produce white, light and colored rubber products. When latex reclaimed rubber is used in combination with natural rubber with high Mooney viscosity such as cigarette film glue and crepe glue, chemical plasticizers can be added in an appropriate amount, such as SJ-103.
4. Design of natural latex recycled rubber anti-aging system
Rubber antioxidants can delay the aging time of rubber products and improve the service life. The antioxidants commonly used in the production of latex recycled rubber products include antioxidant A, antioxidant DNP, antioxidant 4020, antioxidant 4010NA, antioxidant AW, antioxidant MB, antioxidant SP, etc., which can be used separately or together. Latex reclaimed rubber products can use antioxidant RD and antioxidant A when they have high requirements for heat-oxygen aging, and it is recommended to use a large number of antioxidants 4020 and 4010NA when ozone resistance is required, and light-colored reclaimed rubber products need to use non-polluting antioxidants such as antioxidants MB, SP, SP-C, 246 and 2246.
When using latex reclaimed rubber instead of natural rubber to produce various rubber products, it is not only necessary to reasonably design the formula of rubber products, but also to appropriately adjust the production process parameters, especially the mixing process and vulcanization process, and discuss related issues with you later.
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