Selection Of Compounding Agent For Oil-resistant Sealing Ring Compound
Dec 26, 2021
1. Raw rubber system
The oil resistance of rubber depends on the polarity of the rubber and oil. The rubber molecule contains polar groups, such as cyano groups, ester groups, hydroxyl groups, chlorine atoms, etc., which will cause the rubber to exhibit polarity. When a polar rubber and a non-polar petroleum-based product are in contact, the polarity of the two is quite different. From the principle of polymer solvent selection, it is known that the rubber is not easy to swell at this time.
2. Vulcanization system
In general, increasing the cross-linking density can improve the oil resistance of the vulcanizate, because as the cross-linking density increases, the intermolecular force of the rubber increases, and the free volume in the network structure decreases, which has the advantage that the oil is difficult to diffuse. The nitrile rubber vulcanized with organic peroxides, such as DCP and DBP, has permanent compression set, good oil and low temperature resistance, and is not easy to burn. DCP-sulfur/accelerator compound vulcanization system can be used. Commonly used accelerators are: DM , CZ, TMTD
3. Reinforcement system and filling system
Generally, reducing the volume fraction in the rubber compound can improve oil resistance, so increasing the amount of seasoning can help improve oil resistance. Generally, the higher the activity of fillers (such as carbon black and white carbon black) and the stronger the binding force between the rubber, the smaller the volume swelling of the vulcanizate. The hardness of the sealing ring is generally determined by the working pressure, the working pressure is high, and the hardness is also high.
4. Protection System
Oil-resistant rubber is often used in hot oil at a higher temperature, and some products work under both hot oil and hot air conditions. The volume fraction of air dissolved in mineral oil is 10%, 20% to 25% in gasoline, and 13% to 17% in kerosene. Therefore, the problem of thermal oxidative aging must be considered. The antioxidant in oil-resistant rubber is in the oil The stability of it is very important.
