VISCOSITY INDEX ENHANCING ADDITIVE FOR LUBRICATING OILS Russian patent published in 2012 - IPC C10L1/16 C10M143/10 C10M143/12 C08F297/04 C08F287/00 

FIELD: chemistry.

SUBSTANCE: polymer additive which enhances viscosity index is a composition of a hydrogenated block copolymer having at least one polymer block B and, optionally, at least one polymer block A. Before hydrogenation, each block A is a monoalkenylarene homopolymer block, and each block B is a copolymer block with regulated distribution, containing at least one conjugated diene and at least one monoalkenylarene. After hydrogenation, approximately 0-10% arene double bonds are restored and at least approximately 90% conjugated diene double bonds are restored; each block A has number-average molecular weight ranging from approximately 3000 to approximately 60000, and each block B has number-average molecular weight ranging from approximately 20000 to approximately 300000. Each block B has terminal parts adjacent to blocks A, which are rich in conjugated diene links, and one or more parts which are not adjacent to blocks A, which are rich in monoalkenylarene links. The total amount of monoalkenylarene in the hydrogenated block copolymer ranges from approximately 20 wt % to approximately 80 wt %. Content of monoalkenylarene in each block B ranges from approximately 10 wt % to approximately 75 wt %, under the condition that when there is no block A, each block B has terminal parts rich in conjugated diene links, and one or more non-terminal links rich in monoalkenylarene links, and further under the condition that if there is more than one block A, each block A has molecular weight not less than 5000. The composition of the hydrogenated block copolymer is used in amount of 0.2-2.0 wt % in oil compositions for high-efficiency engines.

EFFECT: improved viscosity index of base oil, usually used for engine oil.

8 cl, 1 tbl, 1 ex