| abstract |
The invention pertains to improved lubricating oil dispersants wherein a fractionating polymer is prepared prior to functionalization (e.g., in the Koch reaction) for making dispersant additives. In one aspect, it was discovered that by fractionating a polymer to remove light hydrocarbon and unreacted monomer from the polymer before the carbonylation step of the Koch reaction, the amount of light ester impurities generated was minimized. Light ester is an undesirable byproduct that adversely affects the recycle of the catalyst from the functionalization step of the Koch reaction. The invention also pertains to improved lubricating oil nitrogen-containing dispersant additives derived from fractionated polymer. |