Zinc-free lubricating composition
The invention is directed to a zinc-free lubricating composition for an internal combustion engine containing a phosphorus anti-wear agent, an ashless antioxidant, and an oxyalkylated phenol compound. The lubricating composition provides wear protection, deposit control, and improved acid control with reduced levels of metal-containing additives.
1. A zinc-free lubricating composition comprising:
(a) an oil of lubricating viscosity;
(b) a zinc-free phosphorus-containing antiwear agent;
(c) at least one oxyalkylated hydrocarbyl phenol substituted with at least one aliphatic hydrocarbyl group of 1 to 250 carbon atoms; and
(d) a sulfurized phenol or sulfur-substituted phenol ashless antioxidant.
2. The lubricating composition of claim 1 , wherein the zinc-free phosphorus-containing antiwear agent is selected from phosphites, phosphonates, organic phosphate esters, amine or ammonium phosphate salts, and combinations thereof.
3. The lubricating composition of claim 1 , wherein the oxyalkylated hydrocarbyl phenol is represented by the formula:
wherein each R 2 is independently hydrogen or a hydrocarbyl group of 1 to 6 carbon atoms;
R 3 is hydrogen, a hydrocarbyl group of 1 to 24 carbon atoms, or an acyl group represented by —C(═O)R 5 ,
R 5 is a hydrocarbyl group of 1 to 24 carbon atoms;
each R 4 is independently a hydrocarbyl group of 1 to 250 carbon atoms (typically wherein at least one R 4 contains 20 to 220, or 30 to 150, 35 to 140, or 40 to 96 carbon atoms);
n=1 to 20; and m=1 to 3.
4. The lubricating composition of claim 1 , further comprising further comprises at least one other additive selected from an ashless dispersant, a phosphorus-free ashless anti-wear additive, a friction modifier, a polymeric viscosity modifier, a corrosion inhibitor, and a metal-containing detergent.
5. The lubricating composition of claim 1 , wherein the zinc-free phosphorus antiwear agent is present in an amount to deliver 0.01 weight % to 0.15 weight % phosphorus to the lubricating composition.
6. The lubricating composition of claim 1 , wherein the ashless antioxidant is present in an amount 0.1 weight % to 10 weight % in the lubricating composition.
7. The lubricating composition of claim 1 , further comprising a functionalized polymer compound in an amount 0.2 to 8 percent by weight of the composition, wherein the polymer has a number averaged molecular weight of at least 5000, and the polymer is selected from polyolefins, poly(meth)acrylates, styrene-diene copolymers, copolymers of maleic anhydride and one or more of alpha-olefins and vinyl-aromatic monomers, and combinations thereof.
8. The lubricating composition of claim 1 , further comprising a polyalkenyl succinimide dispersant in an amount from 0.1 to 2.0 weight % of the composition.
9. The lubricating composition of claim 1 , wherein the lubricant composition comprises less than 35 weight % of Group IV base oil.
10. A method of lubricating an internal combustion engine comprising lubricating the engine with a lubricant composition comprising (a) an oil of lubricating viscosity, (b) a zinc-free phosphorus-containing antiwear agent, (c) at least one oxyalkylated hydrocarbyl phenol that is substituted with at least one aliphatic hydrocarbyl group of 1 to 250 carbon atoms, and (d) a sulfurized phenol or sulfur-substituted phenol ashless antioxidant.
11. The method of claim 9 , wherein the engine is fueled with a liquid hydrocarbon fuel, a liquid nonhydrocarbon fuel, or mixtures thereof.
12. The method of claim 9 , wherein the engine is fueled by natural gas, liquefied petroleum gas (LPG), compressed natural gas (CNG), or mixtures thereof.