Olefin polymer viscosity index improver additive useful in oil compositions

A process comprising degrading an oil-soluble ethylene copolymer comprising about 15 to 90 weight % ethylene and about 10 to 85 weight % of C.sub.3 to C.sub.28 alpha-olefin, said copolymer having a number average molecular weight within the range of about 5,000 to 500,000 and grafting with an unsaturated material selected from the group consisting of:

• (A) ethylenically unsaturated C.sub.3 to C.sub.10 carboxylic acid having 1 to 2 carboxylic acid groups or an anhydride group, and (B) nitrogen-containing ethylenically unsaturated monomers containing 6 to 30 carbon atoms and 1 to 4 nitrogen atoms, in the presence of a free radical initiator and a chain stopping agent under nitrogen.

A process for forming a V.I.-dispersant additive for lubricating oil comprising heating and degrading in an inert atmosphere an oil-soluble ethylene-propylene V.I. improving solid rubber copolymer having a T.E of 2.0 and higher to a T.E. of 1.8 or less by heating to 120.degree. C. to 250.degree. C. and mixing the presence of a peroxide free radical generator, grafting said copolymer with maleic anhydride in the presence of said peroxide and a mercaptan chain stopping agent, and reacting said maleic anhydride grafted copolymer with tertiary N-propylamino morpholine.

A lubricating oil composition comprising a major amount of lubricating oil and an oil-soluble V.I. improver prepared by degrading an olefin polymer under an inert atmosphere in the presence of a free radical initiator sufficient to reduce the molecular weight of said polymer.

A lubricating oil composition comprising a major amount of lubricating oil and a V.I.-dispersant additive prepared by degrading an oil-soluble ethylene copolymer comprising about 15 to 90 weight % ethylene and about 10 to 85 weight % of C.sub.3 to C.sub.28 alpha-olefin, said copolymer having a number average molecular weight within the range of about 5,000 to 500,000 and grafting with an unsaturated material selected from the group consisting of:

• (A) ethylenically unsaturated C.sub.3 to C.sub.10 carboxylic acid having 1 to 2 carboxylic acid groups or an anhydride group, and (B) nitrogen-containing ethylenically unsaturated monomers containing 6 to 30 carbon atoms and 1 to 4 nitrogen atoms, in the presence of a free radical initiator and a chain stopping agent under nitrogen.

A lubricating oil composition comprising a major amount of lubricating oil and a V.I.-dispersant prepared by heating and degrading in an inert atmosphre an oil-soluble ethylene-propylene V.I. improving solid rubber copolymer having a T.E. of 2.0 and higher to a T.E. of 1.8 or less by heating to 120.degree. to 250.degree. C. and mixing in the presence of a peroxide free radical generator, grafting said copolymer with maleic anhydride in the presence of said peroxide and a chain stopping agent, and reacting said maleic anhydride grafted copolymer with tertiary N-propylamino morpholine.

A lubricating oil composition having a reduced tendency to viscosity increase due to additive interaction comprising an oil-soluble ashless dispersant and a polyolefin V.I. improver prepared by heating to degradation in the presence of a free radical initiator under nitrogen.

A process for producing a viscosity index improver additive useful in lubricating oil compositions comprising degrading an olefin polymer in the substantial absence of a solvent under an inert atmosphere by heating to about 120.degree. C. to 125.degree. C. in the presence of a free radical initiator sufficient to decrease the molecular weight of said polymer.