Viscosity improver compositions providing improved low temperature characteristics to lubricating oil
AssigneeThe Lubrizol Corporation
InventorsChor Huang, Lewis Breon
Life of this patent
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Abstract
A lubricant composition comprising an oil of lubricating viscosity; (A) 0.05 to 1.5 percent by weight of a copolymer comprising 70 to 79 percent by weight of units derived from ethylene (“E”), having a Mw of 50,000 to 100,000, Mw/ Mn less than 3, density (“D”) of 860 to 896 kg/m3, and a melting point (“Tm”) of 15° C. to 60° C., wherein E and Tm fulfill the expression 3.44E−206≧Tm; and (B) 0.05 to 1.5 percent by weight of a block copolymer comprising a first block which comprises a vinyl aromatic comonomer and a second block which comprises a diene comonomer, the diene monomer-containing block being hydrogenated; wherein the weight ratio (A):(B) is 20:80 to 60:40; exhibits good low temperature performance and durability.
Claims14
A lubricant composition comprising:
- an oil of lubricating viscosity;
- (A) about 0.2 to about 1 percent by weight of a copolymer comprising about 70 to about 79 percent by weight of units derived from ethylene (“E”), having a Mw of about 70,000 to about 95,000, Mw/ Mn less than about 3, density (“D”) of about 860 to about 896 kg/m3, and a melting point (“Tm,”) of about 15° C. to about 60° C., wherein E and Tm fulfill the expression
- 3.44E−206≧Tm;
- wherein the copolymer (A) is an ethylene/propylene copolymer;
- and
- (B) about 0.4 to about 1.5 percent by weight of a block copolymer comprising a first block which comprises a vinyl aromatic comonomer comprising styrene and a second block which comprises a diene comonomer comprising isoprene or 1,3-butadiene, the diene monomer-containing block being hydrogenated;
- wherein the vinyl aromatic content of the block copolymer (B) is about 20 to about 40 weight percent and wherein the weight average molecular weight of the polymer (B) is about 100,000 to about 300,000;
- wherein the weight ratio (A):(B) is about 20:80 to about 60:40, wherein the block copolymer (B) comprises at least one homopolymer or homo-oligomer segment of the vinyl aromatic monomer, and wherein the block copolymer (B) is other than a star polymer.
Dependencies are inferred from the claim text.