FIELD: organic chemistry, polymers.
SUBSTANCE: invention relates to polymers additives for lubricant oils improving viscosity index and representing dispersers. Disperser-additive improving viscosity index is prepared by a method involving grafting in solution on hydrocarbon polymer prepared from at least one (C2-C28)-polymerizing hydrocarbon wherein abovementioned polymer has an average molecular mass value in the range from about 5000 Da to about 500000Da, compounds of ethylene-unsaturated type comprising from 3 to 10 carbon atoms and at least one group of carboxylic acid or anhydride group, or nitrogen-containing monomer of ethylene-unsaturated type comprising from 6 to 30 carbon atoms and from 1 to 4 nitrogen atoms and with using free-radical initiator wherein the process is carried out in the presence of ester as oil corresponding to the formula: 
wherein R1, R2, R3, R4, R5 and R6 are chosen independently from the group consisting of hydrogen atom, -COOR7, -COOR8, -COOR9, -COOR10, -COOR11 and -COOR12 under condition that 5 radicals (not above) among R1, R2, R3, R4, R5 and R6 represent hydrogen atom, and R7, R8, R9, R10, R11 and R12 are chosen independently from the group consisting of alkyl and alkyl esters. Disperser-additive improved viscosity index of lubricant oils and elicits dispersing capacity providing suspending sediment that can form in the process of exploitation or using lubricant and prevents carbon formation in engines. Method shows the improved qualities in grafting in solution of unsaturated fragments on hydrocarbon polymer by carrying out the grafting reaction in solution medium containing at least one aromatic ester.
EFFECT: improved preparing method, valuable technical properties of additive.
20 cl, 4 tbl, 4 ex
