EPDM reclaimed rubber has excellent resistance to high and low temperatures, ozone, and weathering, and is widely used in the production of rubber products such as sealing strips, hoses, shock absorbers, and waterproof materials. Compared with latex reclaimed rubber and tire reclaimed rubber, EPDM reclaimed rubber has obvious aging resistance advantages, which easily leads to the misconception that EPDM reclaimed rubber products do not require anti-aging agents. This is incorrect. Whether EPDM reclaimed rubber products add anti-aging agents should not be judged solely by the type of reclaimed rubber; it must also comprehensively consider the product's operating temperature, heating time, ozone concentration, light intensity, and dynamic flexing conditions.
In actual production, what are the commonly used anti-aging agents for EPDM reclaimed rubber products? What issues should be noted during use?
1. Application of antioxidant RD in EPDM reclaimed rubber products
Antioxidant RD is one of the commonly used antioxidants in EPDM reclaimed rubber products. It can effectively inhibit oxidation, thermal aging, and weather aging under harsh conditions, and is more effective than antioxidant 124, but less effective against flex cracking and stronger inhibition of metal catalytic oxidation. RD has little effect on vulcanization of EPDM reclaimed rubber E6LYY511, is not prone to frosting, and causes pollution but is not significant. Antioxidant RD has a higher molecular weight, less diffusion loss, and longer-lasting protective performance. In long-term use of EPDM reclaimed rubber products, antioxidant RD can be used, generally in dosages of 0.5-2 parts.
2. Application of Anti-Aging Agent 124 in EPDM reclaimed rubber products
Antioxidant 124 protects against heat, oxygen, and weather-related aging, but cannot effectively prevent flexion cracking under harsh conditions. It is polluting but not significant, and the compound may show slight discoloration under light. When using antioxidant 124 for EPDM reclaimed rubber products, the general dosage is 0.5~3 parts, with a maximum of 5 parts; for light-colored EPDM reclaimed rubber products, the blending amount does not exceed 0.25 parts.
3. Application of the anti-aging agent BLE in EPDM reclaimed rubber products
The antioxidant BLE provides excellent protection against heat, oxygen, and flexural fatigue, as well as weather and ozone aging; It improves the fluidity of unvulcanized rubber and has little effect on the vulcanization rate of the compound. If EPDM reclaimed rubber products need to balance thermal and oxygen aging with dynamic fatigue performance, BLE can be considered as an anti-aging agent; BLE has certain pollution properties and is not suitable for producing light-colored and white rubber products.
4. Application of anti-aging agent DNP in EPDM reclaimed rubber products
Antioxidant DNP provides good protection against thermal-oxidative aging and weather-related aging. When used in anti-aging systems for EPDM reclaimed rubber products, it can be used synergistically with anti-aging agent MB. It should be noted that DNP has a significant activation effect on thiazole accelerators.
5. Application of anti-aging agent MB in EPDM reclaimed rubber products
Antioxidant MB is one of the commonly used antioxidants for EPDM reclaimed rubber products. It offers moderate protection against oxygen, weather, and static aging, and can effectively guard against copper damage and adverse effects caused by excessive sulfur during product vulcanization; It disperses easily, does not discolor under sunlight, is slightly polluting, and generally uses 1-1.5 parts. When EPDM reclaimed rubber products use a sulfur-free vulcanization system with a high TMTD content in accelerators, MB provides better protection against steam. When used with antioxidant AP, its resistance to hot air aging can be greatly improved.
6. Application of the anti-aging agent NBC in EPDM reclaimed rubber products
Antioxidant NBC is a typical ozone agent that disperses easily in the compound. When using NBC in EPDM reclaimed rubber products, it may cause the compound to become green and non-polluting.
Aging of EPDM rubber is mainly due to molecular crosslinking, which leads to increased hardness and decreased elasticity and elongation at break after aging.Choosing appropriate antioxidants can effectively delay aging. When choosing antioxidants for EPDM reclaimed rubber products, different types of antioxidants can be chosen according to the requirements of the compound in terms of heat resistance, ozone resistance, flexural crack resistance, and light aging resistance, and the effects of antioxidants on other system additives should be comprehensively considered.
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