Natural rubber is made of latex in rubber trees as raw materials, processed through solidification, drying and other processes, containing more than 90% rubber hydrocarbons, good feel elasticity, high mechanical strength, and widely used in the rubber products industry E5LYY922 However, because natural rubber contains unsaturated double bonds, light, heat, ozone, radiation, flexural deformation, copper, manganese and other metals can promote the aging of rubber, aging resistance has become the Achilles heel of natural rubber, how to improve the aging resistance of natural rubber?
1. Use chemical anti-aging agents to improve the aging resistance of natural rubber
Rubber anti-aging agent can effectively delay the aging of rubber and is an important compound to improve the aging resistance of natural rubber. Commonly used anti-aging agents for natural rubber include anti-aging agent RD, anti-aging agent A, anti-aging agent DNP, anti-aging agent 4020, anti-aging agent 4010NA, anti-aging agent AW, anti-aging agent MB, anti-aging agent SP, anti-aging agent SP-C, anti-aging agent 3100, etc., which can be used alone or in combination.
To improve the aging resistance of natural rubber products, anti-aging agents can be reasonably selected according to the actual use and use conditions. It is required that heat oxygen resistant can use anti-aging agent RD and anti-aging agent A; To require ozone resistance, anti-aging agent 4020, anti-aging agent 4010NA, anti-aging agent AW, anti-aging agent 3100, etc. should be used in large quantities; Light-colored products choose non-polluting anti-aging agents, such as anti-aging agent MB, anti-aging agent SP, anti-aging agent SP-C, anti-aging agent 264, anti-aging agent 2246, etc.
2. Use paraffin to improve the aging resistance of natural rubber
When natural rubber produces static rubber products such as sealing strips, a small amount of microcrystalline paraffin can be added; After vulcanization, microcrystalline paraffin will slowly migrate to the surface, forming a dense physical protective film that effectively isolates ozone erosion and prevents surface cracking. Rubber protective wax and microcrystalline wax are physical anti-aging agents.
3. Improve the rubber refining and vulcanization process of natural rubber products
When natural rubber is molded and mixed, strict control of temperature and time can avoid excessive molecular chain breakage caused by excessive plasticization, resulting in more end groups that are easy to oxidize, and natural rubber products have better aging resistance. Natural rubber vulcanized products can also undergo secondary vulcanization, eliminate internal stress, make the cross-linking network more stable, and reduce the risk of aging during use.
4. Adjust the vulcanization system and reinforcement system of natural rubber products
(1) Vulcanization system: Sulfide natural rubber with effective vulcanization system or semi-effective vulcanization system, compared with the traditional sulfur vulcanization system, can generate more stable single sulfide bonds and disulfide bonds, reduce polysulfide bonds (easy to break, poor heat resistance), and improve the aging performance of natural rubber in heat and oxygen resistance.
(2) Reinforcement system: black and dark natural rubber products can use high-structure carbon black, and the functional groups such as quinone and phenolic groups on the surface can effectively capture free radicals, interrupt the chain reaction, and improve the aging resistance of natural rubber products.
5. Natural rubber is used in combination with other rubbers to improve aging resistance
(1) General synthetic rubber: natural rubber can be used in conjunction with general synthetic rubber, such as styrene-butadiene rubber (wear resistance, heat resistance, aging resistance and vulcanization speed is better than natural rubber), butadiene rubber (its cold resistance and wear resistance are better after vulcanization) are used in appropriate proportions to improve the aging resistance of the rubber material.
(2) Recycled rubber: Recycled rubber has been subjected to intense treatment such as vulcanization, compounding and oxidation in advance during the production process, and has become a stable state that can no longer be changed, especially when exposed to sunlight, and has good weather resistance. In the production of natural rubber products, the rational use of recycled rubber, especially natural latex recycled rubber and tire recycled rubber, can not only reduce the cost of raw materials, but also improve the aging resistance of natural rubber.
High-strength pure latex recycled rubber is made of waste latex gloves as the main raw material and part of the landing natural glue is added in the production process, after crushing, desulfurization, disinfection, drying, filtration and other processes, the effective rubber hydrocarbon content reaches more than 75%, with high strength, small specific gravity, good feel elasticity, easy color matching, no taste, high tearing elongation, simple refining process and saving labor and electricity costs, etc., is an ideal raw material to replace natural rubber to produce all kinds of rubber products and reduce costs.
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