POLAR GRAFT POLYOLEFINS, METHOD OF PREPARATION THEREOF, LUBE OIL COMPOSITIONS CONTAINING THEM, AND METHODS FOR PREPARING DISPERSING AGENT Russian patent published in 2002 - IPC

FIELD: polymer production. SUBSTANCE: invention provides graft copolymer prepared by a method including addition of nitrogen-containing ethylenically unsaturated aliphatic or aromatic monomer containing 2 to 50 carbon atoms and an initiator to solution of polyolefin, main chain of which contains unsaturation to be grafted, in solvent heated to temperature of reaction, on which essentially all amount of initiator is consumed during reaction time, solvent being a lube oil fraction solvent containing less than about 9 wt % of aromatic impurities, to which monomer and initiator are added together or in succession. Initiator is added to solvent at a velocity constituting at least about 0.1% of initiator in a minute. A graft copolymer is obtained with asphaltene dispersibility value at least about 4. Invention also provides lube oil compositions containing graft copolymer and methods for preparing dispersing agent. Use of graft copolymer allows preparing lube oil with asphaltene dispersibility index higher than 2 and dispersing agents with improved viscosity index. EFFECT: extended resources of lubricants. 35 cl, 6 tbl, 9 ex