Recently, the price of nitrile rubber has continued to rise. As a low-cost raw material for nitrile rubber, nitrile reclaimed rubber has naturally become an ideal choice for nitrile rubber manufacturers. Buna-N reclaimed rubber can be used alone or in combination with Buna-N rubber to produce various oil-resistant rubber products, such as oil-resistant washers, gaskets, oil seals, oil-resistant rubber shoes, oil-resistant rubber tubes, etc., effectively reducing the cost of raw materials. In actual production, when using nitrile rubber to produce oil-resistant rubber products working in different oil media, the curing system design is very important.
The oil resistance of nitrile rubber products is directly related to the curing crosslinking density and the type of crosslinking bond. With the increase of crosslinking density, the intermolecular force of the rubber increases, and the free volume in the network structure decreases, which has the advantage that oil is difficult to diffuse, so the oil resistance of the nitrile rubber vulcanizate can be improved; The influence of the type of crosslinking bond on the oil resistance of nitrile rubber is closely related to the type and temperature of oil.
1. Selection of vulcanization system for oil-resistant rubber products working in oxidized fuel oil in the production of nitrile rubber
When the cost of oil-resistant rubber products working in oxidized fuel oil is reduced by using nitrile rubber, the oil resistance of 2SLYY220 vulcanizate cured with peroxide or semi-effective vulcanization system is better than that of sulfur vulcanizate. The stability of nitrile rubber and nitrile rubber/reclaimed rubber blends vulcanized with peroxide is the highest at 40 ℃, but it is not ideal in oxidized fuel at 125 ℃; The nitrile rubber vulcanized with cadmium oxide and sulfur feeding system has good resistance to long-term hot oil aging in oxidized fuel at 125 ℃.
2. Selection of curing system for oil-resistant rubber products working in mineral oil
It is recommended to use cadmium oxide/sulfur donor when producing rubber products working in mineral oil at 150 ℃ using nitrile rubber
The heat oil aging resistance of the vulcanizate is better than that of the regenerated nitrile rubber vulcanizate cured by other curing systems.
The change of curing system has little effect on the oil resistance of the reclaimed nitrile rubber vulcanizate, but has great influence on the cold resistance. The brittleness temperature of NBR vulcanizate with sulfur curing system is higher and its cold resistance is poor; The vulcanizate cured with DCP and DCP with a small amount of sulfur has a low brittleness temperature and good cold resistance. It should be noted that the curing rate of DCP is slow, and the comprehensive performance of the vulcanizate using DCP alone is worse than that using DCP plus a small amount of sulfur. Therefore, it is recommended to use DCP plus a small amount of sulfur curing system to produce low-temperature oil-resistant products using nitrile rubber regeneration.
When using nitrile rubber to reduce the production cost of oil-resistant rubber products, the design of reinforcing and filling system and softening and plasticizing system will also affect the oil resistance of vulcanizates. The editor will continue to discuss relevant issues with you later.
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