The main raw material of the oil-resistant rubber sheet is nitrile rubber. This type of highly polar elastomer is a copolymer of butadiene and acrylonitrile (ACN). The acrylonitrile component imparts oil resistance to the elastomer, and the oil resistance increases with the increase of the acrylonitrile content. However, the increase in the acrylonitrile content will damage its low-temperature flexibility and increase the hardness of the rubber compound. Generally, the content of ACN is between 18% and 4%.
In terms of price, NBR is the lowest price among oil-resistant elastomers. Its oil resistance is better than that of neoprene rubber sheet, but it is inferior to polysulfide rubber. Its heat aging resistance is better than natural rubber sheet. The nitrile rubber sheet does not crystallize when stretched, so a reinforcing agent is needed to increase the strength of the rubber sheet; its tear resistance is inferior to that of natural rubber sheets.
Formulators can choose from a variety of curing systems. The products used at high temperature can usually choose peroxide and thiuram, or use phazole or sulfenolamine and use thiuram as a promoter. Peroxide can be used in combination with active additives and sulfur with thiazole or sulfophthalamide.
Some anti-degradation agents are added to the nitrile rubber sheet to improve the performance of the rubber compound. Some manufacturers permanently incorporate antioxidants into polymer molecules to increase their heat resistance. Compared with the addition of antioxidants in the rubber compounding stage, the antioxidants combined in this way are more difficult to extract. HNBR can be vulcanized with sulfur or peroxide system, and the shore hardness of the compound can be above 30-90. HNBR has good resistance to flexural fatigue and can be used at high and low temperatures through compounding. Product markets include synchronous timing belts, power steering systems and other automotive applications.
Sodium nitrile butadiene rubber, also known as XNBR or CNBR, is higher in strength and wear resistance than ordinary nitrile rubber sheets. This is because fusidic acid groups are introduced on the polymer backbone during the manufacturing process. During the vulcanization process, the mass increases the crosslinking point during vulcanization.
The blending of NBR and PVC can improve ozone resistance. Before granulation. Add NBR to the plasticized PVC and mix in the internal mixer. The mixed product is a PVC-based rubber compound similar to a rubber sheet, which has better wear resistance and compression set than ordinary PVC.
The above information is provided by industrial rubber sheet supplier.