At present, nitrile rubber is one of the main raw materials for producing oil-resistant seals. Its oil resistance is better than that of EPDM, butyl rubber, styrene-butadiene rubber and other synthetic rubbers, second only to polysulfide rubber and fluororubber; The nitrile rubber with good acrylonitrile content of 39-42% is equivalent to butyl rubber; it is a cost-effective raw material for producing oil resistant seals. As a rubber compound processed from waste nitrile rubber, the nitrile reclaimed rubber can theoretically be used together with nitrile rubber to produce a sealing ring to maintain a good sealing effect; however, in actual production, the nitrile sealing ring is used in production. There are many techniques to master when producing nitrile rubber + nitrile reclaimed rubber.
1. Pay attention to the acrylonitrile content of nitrile rubber used in the nitrile seal.
The acrylonitrile content of different grades of nitrile rubber and nitrile reclaimed rubber produced by different manufacturers has a certain difference. The acrylonitrile content of nitrile rubber directly affects its oil resistance, heat resistance, cold resistance and various physical indexes. The higher the nitrile rubber acrylonitrile content, the better the tensile strength, heat resistance, oil resistance and air tightness of the rubber compound, and the greater the hardness, but the elasticity and cold resistance of the product are reduced. Therefore, when using nitrile rubber/recycled rubber to produce the sealing ring, pay attention to the working condition of the sealing ring. For the sealing ring with high cold resistance, the high acrylonitrile content of nitrile rubber cannot be used.
2, pay attention to the ratio of nitrile reclaimed rubber and nitrile rubber
The raw material of nitrile reclaimed rubber is nitrile water, rubber, waste nitrile rubber and waste nitrile gloves. The nitrile reclaimed rubber processed by different raw materials has different rubber content, and the difference between product performance and nitrile rubber is different. When the ratio of the nitrile reclaimed rubber to the nitrile rubber in the nitrile seal is required, the amount of nitrile reclaimed rubber to replace the nitrile rubber should be determined according to the amount of nitrile reclaimed rubber and the nitrile seal ring index. Analysis; usually the ratio of nitrile rubber to nitrile reclaimed rubber in high performance sealing ring can be added in a ratio of 2:1 to maintain a good sealing effect for a long time.
3, pay attention to the choice of anti-aging agent in the formula of nitrile seal ring
Nitrile rubber and reclaimed rubber have good oil resistance, thermal stability, air tightness, etc., but the product itself has poor ozone resistance and electrical insulation. Therefore, when designing nitrile rubber/recycled rubber seal formula, anti-aging The system design directly affects the service life of the nitrile seal. Antioxidant SP is low in pollution and is a hot oxygen stabilizer commonly used in the production of nitrile rubber products. It can significantly improve the oxidation resistance and heat resistance of products in the production of nitrile seals. The dosage can be controlled at about 1.5-2 parts; the antioxidant BLE can be obtained by condensation of acetone and diphenylamine under high temperature and high pressure. It is a non-toxic light gray solid, which is caused by heat, oxygen, ozone, climate and flexion. The aging problem has a significant inhibitory effect and is easily dispersed in the rubber compound, so that 0.8-1 parts of the antioxidant BLE can be added to the nitrile seal.
4, pay attention to the processing of nitrile rubber / reclaimed rubber seals
In actual production, the nitrile reclaimed rubber/rubber sealing ring is generally prepared by a mixing process. After the nitrile rubber and the reclaimed rubber are obtained by weight, they are thoroughly kneaded and then mixed with other raw materials to be fully kneaded. Forming the seal ring, the entire production process needs to be controlled by someone.
The addition of an appropriate amount of nitrile reclaimed rubber in the nitrile seal can produce a nitrile seal with excellent sealing performance and high temperature resistance. It can also improve the processing technology, save the amount of nitrile rubber, and save processing costs and raw materials. cost.
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