Lube oil additive

Claim 2

A modified hydrogenated star-shaped polymer comprising a poly-vinyl-aromatic nucleus and polymeric arms linked to said nucleus wherein said arms are selected from the group consisting of: (i) hydrogenated homopolymers and hydrogenated copolymers of conjugated dienes; (ii) hydrogenated copolymers of conjugated dienes and monoalkenyl arenes; and (iii) mixtures thereof; and wherein at least about 80% of the aliphatic unsaturation of the star-shaped polymer has been reduced by hydrogenation while less than 20% of the aromatic unsaturation has been reduced; and which star-shaped polymer has been grafted with a nitrogen containing polymerizable organic polar compound selected from the group consisting of piperidine, morpholine, piperazine, pyridine, pyrrolidone, pyrrole, benzopyrrole, quinoline, indole which are all alkenyl substituted and 2-methyl vinylpyridine and N-vinyl imidazole in the presence of a free radical polymerization initiator and wherein the number average molecular weight of each of said polymeric arms is from 5,000 to 150,000.

Claim 3

The polymer as claimed in claim 1, wherein the nitrogen containing compound is 2-vinylpyridine or 4-vinylpyridine.

Claim 4

The polymer as claimed in claim 1 wherein the nucleus is a poly(divinylbenzene) nucleus.

Claim 5

The polymer as claimed in claim 3, wherein the nucleus is a poly(di-vinyl-benzene/monoalkenyl aromatic) nucleus.

Claim 6

The polymer as claimed in claim 1, wherein the number of polymeric arms is from 5 to 10.

Claim 7

The polymer as claimed in claim 1, wherein the number average molecular weight of the hydrogenated star-shaped polymer is from 25,000 to 1,500,000.

Claim 8

The polymer as claimed in claim 1, wherein each polymeric arm is a hydrogenated polyisoprene homopolymer.

Claim 9

A process for preparing a dispersant/VI improver comprising reacting a selectively hydrogenated star-shaped polymer with a nitrogen containing polymerizable organic polar compound in the presence of a free radical polymerization initiator at a temperature of about 70° C. to about 180° C. and at a pressure of from 1 bar to 50 bar in an inert atmosphere wherein said star-shaped polymer comprises a poly(poly-vinyl-aromatic coupling agent) nucleus, and at least four polymeric arms linked to said nucleus wherein said polymeric arms are selected from the group consisting of: (i) hydrogenated homopolymers and hydrogenated copolymers of conjugated dienes; (ii) hydrogenated copolymers of conjugated dienes and monoalkenyl arenes; and (iii) mixtures thereof; and wherein at least about 80% of the aliphatic unsaturation of the star-shaped polymer has been reduced by hydrogenation while less than 20% of the aromatic unsaturation has been reduced, wherein said nitrogen compound is selected from the group consisting of piperidine, morpholine, piperazine, pyridine, pyrrolidone, pyrrole, benzopyrrole, quinoline, indole which are all alkenyl substituted and 2-methyl vinylpyridine and N-vinyl imidazole and wherein the number average molecular weight of each of said polymeric arms is from 5,000 to 150,000.

Claim 10

A process for preparing a dispersant/VI improver comprising reacting a selectively hydrogenated star-shaped polymer with a nitrogen containing polymerizable organic polar compound in the presence of a free radical polymerization initiator at a temperature of about 70° C. to about 180° C. and at a pressure of from 1 bar to 50 bar in an inert atmosphere wherein said star-shaped polymer comprises a poly(poly-vinyl-aromatic coupling agent) nucleus, and at least four polymeric arms linked to said nucleus wherein said polymeric arms are selected from the group consisting of: (i) hydrogenated homopolymers and hydrogenated copolymers of conjugated dienes; (ii) hydrogenated copolymers of conjugated dienes and monoalkenyl arenes; and (iii) mixtures thereof; and wherein at least about 80% of the aliphatic unsaturation of the star-shaped polymer has been reduced by hydrogenation while less than 20% of the aromatic unsaturation has been reduced, wherein said nitrogen compound is selected from the group consisting of piperidine, morpholine, piperazine, pyridine, pyrrolidone, pyrrole, benzopyrrole, quinoline, indole which are all alkenyl substituted and 2-methyl vinylpyridine and N-vinyl imidazole and wherein the number average molecular weight of each of said polymeric arms is from 5,000 to 150,000.

Claim 11

The process as in claim 8 wherein the inert atmosphere is a nitrogen atmosphere.

Claim 12

The process as in claim 8 wherein the reaction is carried out in cyclohexane.

Claim 13

A lubricating composition comprising a major amount of a lubricating oil and from 0.1 to about 15.0 weight percent of the oil-soluble product of claim 1.

Claim 14

A concentrated lubricating composition comprising a lubricating oil and from 15 to 45 weight percent of the oil-soluble produce to claim 1.