Patent ID: 6753381
Filing Date: 2004-06-22
Classification: C08F,C08L,C10M,C10N

Abstract:
A lubricating oil composition comprising a major amount of oil of a lubricating viscosity, a performance additive package appropriate for the quality and performance levels, a pour point depressant, and a viscosity index improving amount of an oil soluble polymer mixture comprising: an ethylene-propylene polymer blend having a number average molecular weight within the range of about 20,000 to about 300,000 and a molecular weight distribution within the range of about 1.3 to about 5 prepared by the process comprising blending or simultaneously blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 40,000 to about 300,000 and a molecular weight distribution within the range of about 1.3 to about 5.0; and (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having 3-25 weight percent crystallinity, and, having a number average molecular weight within the range of about 40,000 to about 300,000 and a molecular weight distribution within the range of about 1.3 to about 5.0; whereby the blending, or simultaneous blending and shearing, is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of(a) and (b), wherein the weight ratio of the low ethylene content ethylene-propylene polymer (a) to the higher ethylene content ethylene-propylene polymer (b) is within the range of about 45/55 to about 10/90.