Nitrogen-free phosphorus compounds and lubricants containing the same
A composition obtained by reacting an O,O′-dialkyldithiophosphoric acid with a hydroxyalkyl acrylate or a hydroxyalkyl methacrylate, and reacting the product thereof with a dialkylphosphite provides good antiwear protection.
1. A lubricant composition comprising:
an oil of lubricating viscosity;
a material represented by the formula
wherein R 1 and R 2 are each independently hydrocarbyl groups of 3 to about 12 carbon atoms, or are groups represented by
or wherein R 1 and R 2 together with the adjacent O and P atoms form a ring containing 2 to 6 carbon atoms; R 3 is hydrogen or a methyl group, R 4 is an alkylene group of 2 to 6 carbon atoms, R 5 is hydrogen or a hydrocarbyl group of 1 to about 12 carbon atoms, and n is 1 or 2; and
a metal dialkyldithiophosphate.
2. The lubricant composition of claim 1 , wherein the material is represented by the formula
3. The lubricant composition of claim 1 , wherein R 1 and R 2 are 2-ethylhexyl groups or 4-methyl-2-pentyl groups or mixtures thereof.
4. The lubricant composition of claim 1 , wherein the metal dialkyldithiophosphate is zinc dialkyldithiophosphate (ZDDP).
5. The lubricant composition of claim 4 , wherein the ZDDP is zinc di-(octyl) dithiophosphate.
6. The lubricant composition of claim 4 , wherein the ZDDP is zinc di-(2-ethylhexyl) dithiophosphate.
7. The lubricant composition of claim 1 , wherein the amount of the material in the lubricant composition is about 0.01 to about 5 percent by weight of the lubricant composition.
8. The lubricant composition of claim 1 , wherein the metal dialkyldithiophosphate is present in the lubricant composition in an amount of from 0.05 to 2.5 weight percent of the lubricant composition.
9. A method for lubricating a surface, comprising supplying thereto the lubricant of claim 1 .
10. The method of claim 9 , wherein the surface is a part of a transmission, a clutch, a gear, a hydraulic system, a metal-working system, or an internal combustion engine.
11. The method of claim 9 , wherein the surface is a part of a farm tractor or an off-highway vehicle.