Fluoroelastomer Resistant to Automotive Lubricants
There are many kinds of lubricants such as automatic transmission fluid, brake fluid, bearing grease, etc. used in automotive vehicles. Fluoroelastomers have been used for a long time for oil seals contacting such lubricants. Fluoroelastomers composed of vinylidene fluoride, hexafluoropropylene, and optionally incorporated tetrafluoroethylene are designated as FKM, which have been one of the most popular fluoroelastomers. The latest automotive lubricants tend to contain a large amount of additives to improve the performance along with the demanding driving conditions. Such additives, however, are reactive with FKM at elevated temperatures to raise the hardness of FKM, which results in losing the sealing performance. An elastomer material which does not lose the flexibility in the long-term exposure to the lubricant has been desired.