Heat-resistant rubber has high requirements for the heat resistance of the rubber materials used, and EPDM recycled rubber, butyl recycled rubber, nitrile recycled rubber and other raw rubber can replace the appropriate proportion of raw rubber to produce heat-resistant rubber products and reduce production costs. When using recycled rubber to produce heat-resistant rubber products, the formulation design of rubber products directly affects the heat resistance of the finished product, especially the compounds in the vulcanization system, reinforcement filling system, softening plasticization system and anti-aging system.
1. Design of heat-resistant rubber vulcanization system for the production of recycled rubber
Different vulcanization systems produce different cross-linked bond structures. Usually, C—C crosslinked bonds have the best heat resistance, followed by monosulfide bonds, and polysulfide bonds have the worst heat resistance. When using recycled rubber to produce heat-resistant rubber products, it is recommended to use low-sulfur and high-promotion systems, effective vulcanization systems, peroxide vulcanization systems or other sulfur-free vulcanization systems.
When using peroxide vulcanization of heat-resistant recycled rubber products, attention should be paid to the amount of peroxide, as excessive dosage will lead to high cross-linking density of the compound and the deterioration of the vulcanized adhesive performance of the recycled adhesive. Insufficient E5LYY620 peroxide dosage will cause a decrease in cross-linking density, resulting in a decrease in the heat resistance of recycled rubber vulcanized adhesives. In the production of heat-resistant recycled rubber products, EPDM recycled rubber is recommended to be vulcanized with peroxide, nitrile recycled rubber can be vulcanized with cadmium magnesium, and butyl recycled rubber is recommended with resin vulcanization.
2. Design of reinforced rubber reinforcement filling system for the production of heat-resistant rubber
Among rubber reinforcements and fillers, inorganic fillers generally have better heat resistance than carbon black. When using recycled rubber to produce rubber products with high heat resistance, silica, activated zinc oxide, magnesium oxide, alumina and silicate are commonly used compounds. When nitrile recycled rubber products are reinforced with carbon black, the smaller the particle size of carbon black, the lower the heat resistance of vulcanized glue. Silica can improve the heat resistance of recycled glue; Magnesium oxide and alumina can also improve the heat resistance of nitrile recycled adhesive vulcanized adhesive to a certain extent.
Recycled rubber heat-resistant rubber products using peroxide vulcanization need to pay attention to their acidity and alkalinity when choosing reinforcing agents and fillers.
3. Design of heat-resistant rubber softening system for recycled rubber production
The relative molecular weight of the softener is low, and it is easy to volatilize or migrate and exude at high temperature, which can easily lead to problems such as increased hardness and reduced elongation of recycled rubber vulcanized rubber. When using recycled rubber to produce heat-resistant rubber products, it is recommended to choose softeners with good thermal stability and non-volatility at high temperatures, such as petroleum-based softeners with high flash points, polyester plasticizers with large relative molecular weight and high softening points.
In the formulation of recycled rubber heat-resistant rubber products, nitrile recycled rubber can be made of coumarone resin, styrene-indenum resin, polyester and liquid nitrile rubber as softeners; It is recommended to use coumalone resin with a dosage of no more than 5 parts, or 10-20 parts of petroleum jelly or paraffin oil, mineral rubber and petroleum asphalt resin; EPDM recycled rubber generally uses naphthenic oil and paraffin oil as softeners.
4. Design of anti-aging system for the production of heat-resistant rubber with recycled rubber
When recycled rubber produces heat-resistant rubber products, the rational use of high-efficiency heat-resistant anti-aging agents can significantly improve the heat resistance of rubber, and different varieties of recycled rubber should use different anti-aging agents: for example, butyl recycled rubber uses phenolic anti-aging agents such as 2246 can significantly improve the heat resistance of recycled rubber, and nitrile recycled rubber is commonly used anti-aging agents BLE, RD, MB, 4010, D, etc. In order to reduce the fatigue damage caused by multiple deformation of rubber at high temperature, the anti-aging agent with good fatigue resistance can be used together with the anti-aging agent, and the dosage of the anti-aging agent is 1.5%-2.0% of that of raw rubber.
To design the formula of heat-resistant rubber products containing recycled rubber, rubber product manufacturers need to choose the appropriate recycled rubber variety according to specific needs, and reasonably determine the variety and dosage of each compound in the formula, which can further optimize the comprehensive performance of recycled rubber heat-resistant rubber products while reducing costs.
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