Polar grafted polyolefins, methods for their manufacture, and lubricating oil compositions containing them

A method of making a dispersant viscosity index improver, wherein the method comprises:

• A. providing a polyolefin, an initiator, and two or more nitrogenous, ethylenically unsaturated, aliphatic or aromatic monomers having from 2 to about 50 carbon atoms;
• B. mixing each of the monomers with the polyolefin, thereby forming a mixture;
• and
• C. adding sufficient initiator to graft all the monomers to the polyolefin, wherein the initiator is added to the polyolefin at an average rate of addition of less than about 20% of the amount sufficient to graft the monomers to the polyolefin per minute of addition, the addition being carried out at a temperature at about or exceeding the initiation temperature of the initiator;
• thereby forming a graft copolymer reaction product of the monomers grafted on the polyolefin.

The graft reaction product of an ethylenically-unsaturated, nitrogen- and oxygen-containing monomer grafted on a polyolefin backbone, wherein said monomer is selected from the group consisting of:

• 1-vinyl-2-pyrrolidinone,
• 1-vinyl pyrrolidone,
• N-methyl-N-vinylacetamide,
• di-allyl formamide,
• N-methyl-N-allyl formamide,
• N-ethyl-N-allyl formamide,
• N-cyclohexyl-N-allyl formamide,
• N-vinyl succinimide,
• Vinylmorpholines,
• dimethylaminoethyl methacrylate,
• dimethylaminoethyl acrylate,
• maleimide,
• N-vinyl oxazolidone,
• ethyl 2-cyanoacrylate,
• N-vinylphthalimide,
• N-(1,1-dimethyl-3-oxobutyl) acrylamide,
• N-(1,2-dimethyl-1-ethyl-3-oxobutyl) acrylamide,
• N-(1,3-diphenyl-1-methyl-3-oxopropyl)acrylamide,
• N-(1-methyl-1-phenyl-3-oxobutyl) methacrylamide,
• N,N-diethylaminoethyl acrylamide,
• 2-hydroxyethyl acrylamide,
• N-vinylthiopyrrolidone,
• 3-methyl-1-vinylpyrrolidone,
• 4-methyl-1-vinylpyrrolidone,
• 5-methyl-1-vinylpyrrolidone,
• 3-ethyl-1-vinylpyrrolidone,
• 3-butyl-1-vinylpyrrolidone,
• 3,3-dimethyl-1-vinylpyrrolidone,
• 4,5-dimethyl-1-vinylpyrrolidone,
• 5,5-dimethyl-1-vinylpyrrolidone,
• 3,3,5-trimethyl-1-vinylpyrrolidone,
• 4-ethyl-1-vinylpyrrolidone,
• 5-methyl-5-ethyl-1-vinylpyrrolidone,
• 3,4,5-trimethyl-3-ethyl-1-vinylpyrrolidone,
• N-dimethylaminopropyl acrylamide,
• N-dimethylaminopropyl methacrylamide,
• N-methacryloxyethylpyrrolidone,
• N-methacryloxyethylmorpholinone,
• N-methacryloxyethylmorpholine,
• N-maleimide of dimethylaminopropylamine,
• N-methacrylamide of aminoethylethyleneurea,
• 2-vinyl thiobenzothiazole,
• 2-allylthiobenzothiazole,
• 2-butenylthiobenzothiazole,
• N-vinylphenothiazine,
• N-allylphenothiazine,
• N-vinyl pyrrolidone,
• N-vinyl methyl-5 pyrrolidone,
• N-vinylmethyl-3 pyrrolidone,
• N-vinylethyl-5 pyrrolidone,
• N-vinyldimethyl-5,5-pyrrolidone,
• N-vinylphenyl-5 pyrrolidone,
• N-allylpyrrolidone,
• N-vinylthiopyrrolidone,
• N-vinylpiperidone,
• N-vinyl-diethyl-6,6-piperidone,
• N-vinylcaprolactam,
• N-vinylmethyl-7-caprolactam,
• N-vinylethyl-7-caprolactam,
• N-vinyldimethyl-7,7-caprolactam,
• N-vinylthiocaprolactam,
• N-allylcaprolactam,
• N-vinylcapryllactam,
• 4-alkyl morpholine,
• benzoyl acetonitrile,
• hydrocinnamonitrile,
• N-vinylpiperazinoacetophenone,
• 1-(2-methoxyphenyl)-N-vinylpiperazine,
• N-vinyl-5-methoxy-2-pyrrolidinone,
• 4-Methoxy-3-pyrrolin-2-one,
• and combinations of said monomers, said graft reaction product having a weight average molecular weight of from about 20,000 to about 500,000 and a molar proportion of grafted monomer to the polyolefin backbone of at least about 13:1.

A method of making a dispersant viscosity index improver, wherein the method comprises:

• A. providing a polyolefin, an initiator, and an ethylenically unsaturated, aliphatic or aromatic, oxygen- and nitrogen-containing monomer having from 2 to about 50 carbon atoms;
• B. dissolving said polyolefin in a solvent, forming a solution;
• C. dispersing at least a portion of said monomer in said solution;
• and
• D. adding at least a portion of said initiator to said solution at an average rate of addition of less than about 20% of the amount sufficient to graft said monomer to said polyolefin per minute of addition, the addition being carried out at a temperature exceeding the initiation temperature of said initiator;
• thereby forming a graft reaction product of said monomer on said polyolefin, said graft reaction product having a weight average molecular weight of from about 20,000 to about 500,000 and a molar proportion of grafted monomer to the polyolefin of at least about 13:1.

A method of making a dispersant viscosity index improver, comprising the steps of:

• A. providing a polyolefin, an initiator, and an ethylenically unsaturated, aliphatic or aromatic, oxygen- and nitrogen-containing monomer having from 2 to about 50 carbon atoms;
• B. providing an amount of an initiator sufficient to graft said monomer to said polyolefin;
• C. melt-blending a reaction mixture consisting essentially of said monomer, said polyolefin, and said initiator;
• said melt-blending step being carried out substantially in the absence of a solvent, at a temperature and under conditions effective to graft said monomer on said polyolefin;
• said graft reaction product having a weight average molecular weight of from about 20,000 to about 500,000 and a molar proportion of grafted monomer to the polyolefin of at least about 13:1.

A lubricating oil comprising:

• A. at least about 70% of a lubricant base oil;
• B. at least about 0.25% of a graft reaction product of a nitrogen- and oxygen-containing, ethylenically unsaturated, aliphatic or aromatic monomer having from about 2 to about 50 carbon atoms grafted on a polyolefin, said graft reaction product having a weight average molecular weight of from about 20,000 to about 500,000 and a molar proportion of grafted monomer to the polyolefin of at least about 13:1 and of at most about 120:1;
• C. at least about 0.05% solids by weight of one or more polyolefins other than the graft reaction product;
• D. from about 0.5% to about 4% by weight of one or more dispersants which are not grafted polyolefins;
• E. at least about 0.3% by weight of one or more detergents;
• F. at least about 0.01% by weight one or more anti-wear agents;
• G. at least about 0.01% by weight of one or more anti-oxidants;
• and
• H. at least about 0.005% of minor ingredients.