Patent ID: 6712991
Filing Date: 2004-03-30
Classification: C08F,C10M,C10N

Abstract:
A method of making a viscosity index improving additive for a hydraulic fluid, comprising:heating a reaction mixture to a reaction temperature from about 75Â° C. to about 95Â° C., said reaction mixture comprising: from about 55 weight percent to about 99.5 weight percent of a first monomer selected form the group consisting of (C8-C15)alkyl meth)acrylates and mixtures thereof; from about 0.5 weight percent to about 45 weight percent of a second monomer selected from the group consisting of (C1-C7)alkyl (meth)acrylates, (C16-C24)alkyl (meth)acrylates and mixtures thereof; an effective amount of a polymerization initiator selected from the group consisting of 2,2â€²-azobis (2-methylbutanenitrile), 2,2â€²-azobis (2,4-dimethylpentanenitrile), and mixtures thereof; and a hydrocarbon diluent; and maintaining the reaction mixture at the reaction temperature of about 75Â° C. to about 95Â° C., for a period of time effective to allow copolymerization of the monomers.