Viscosity index improver for lubricating oils

Abstract

A polymeric viscosity index improver that includes a hydrogenated block copolymer having at least one controlled distribution block copolymer having a minimized crystallinity is provided. An oil composition including at least a base oil and the aforementioned viscosity index improver is also provided. A polymeric concentrate including the aforementioned viscosity index improver is further provided.

Description

Claims

1. A polymeric viscosity index (VI) improver comprising a hydrogenated block copolymer having at least one polymer block B and optionally at least one polymer block A, and wherein: a. prior to hydrogenation each A block is a mono alkenyl arene homopolymer block and each B block is a controlled distribution copolymer block of at least one conjugated diene and at least one mono alkenyl arene;b. subsequent to hydrogenation about 0-10% of the arene double bonds have been reduced, and at least about 90% of the conjugated diene double bonds have been reduced;c. each A block has a number average molecular weight between about 3,000 and about 60,000 and each B block has a number average molecular weight between about 20,000 and about 300,000;d. each B block comprises terminal regions adjacent to the A blocks that are rich in conjugated diene units and one or more regions not adjacent to the A blocks that are rich in mono alkenyl arene units;e. the total amount of mono alkenyl arene in the hydrogenated block copolymer is from about 20 percent weight to about 80 percent weight; andf. the weight percent of mono alkenyl arene in each B block is between about 10 percent and about 75 percent,

2. The VI improver of claim 1 wherein said mono alkenyl arene is styrene and said conjugated diene is selected from the group consisting of isoprene and butadiene.

3. The VI improver of claim 2 wherein said conjugated diene is butadiene, and wherein from about 15 to about 30 mol percent of the condensed butadiene units in block B have a 1,2-configuration.

4. The VI improver of claim 2 wherein said conjugated diene is butadiene, and wherein from about 18 to about 22 mol percent of the condensed butadiene units in block B have a 1,2-configuration.

5. The VI improver of claim 1 wherein said polymer block B has a mono alkenyl arene blockiness index of less than about 40 mol percent.

6. The VI improver of claim 2 wherein the polymer is an ABA polymer, each block B has a center region with a minimum ratio of butadiene units to styrene units and each A has a molecular weight of less than about 5000.

7. The VI improver of claim 2 wherein the weight percent of styrene in each B block is between about 10 percent and about 50 percent, and the styrene blockiness index of each block B is less than about 10 percent, said styrene blockiness index being defined to be the proportion of styrene units in the block B having two styrene neighbors on the polymer chain.

8. The VI improver of claim 1 wherein said hydrogenated block copolymer has a general configuration (B)m, A-B, A-B-A, (A-B)n, (A-B-A)n, (A-B)n-A, (A-B-A)nX, (A-B)nX, (B-A-B)n, (B-A-B)nX or a mixture thereof, where n is an integer from 2 to about 60, X is coupling agent residue, and m is an integer from 1 to about 60.

9. The VI improver of claim 8 wherein said hydrogenated block polymer has the general configuration (B)m wherein each of the B blocks comprises terminal regions that are rich in conjugated diene units and one or more non-terminal regions that are rich in mono alkenyl arene.

10. The VI improver of claim 1 wherein said hydrogenated block copolymer is a S-EB/S type polymer, wherein the S block has a molecular weight from about 30,000 to about 50,000, the EB unit of the EB/S block has a molecular weight from about 50,000 to about 65,000, the S unit of the EB/S block has a molecular weight from about 30,000 to about 40,000, the EB/S block is selectively hydrogenated to remove at least 90% of the butadiene double bonds, the styrene content of the EB/S block is from about 30 to about 40 weight percent, the 1,2/1,4-butadiene ratio is from about 15/85 to about 30/70, and the total styrene content of the S-EB/S type polymer is from about 50 to about 65.

11. An oil composition comprising: a base oil; anda viscosity improving amount of a hydrogenated block copolymer having at least one polymer block B and optionally at least one polymer block A, and wherein: a. prior to hydrogenation each A block is a mono alkenyl arene homopolymer block and each B block is a controlled distribution copolymer block of at least one conjugated diene and at least one mono alkenyl arene; b. subsequent to hydrogenation about 0-10% of the arene double bonds have been reduced, and at least about 90% of the conjugated diene double bonds have been reduced;c. each A block has a number average molecular weight between about 3,000 and about 60,000 and each B block has a number average molecular weight between about 20,000 and about 300,000;d. each B block comprises terminal regions adjacent to the A blocks that are rich in conjugated diene units and one or more regions not adjacent to the A blocks that are rich in mono alkenyl arene units;e. the total amount of mono alkenyl arene in the hydrogenated block copolymer is from about 20 percent weight to about 80 percent weight; andf. the weight percent of mono alkenyl arene in each B block is between about 10 percent and about 75 percent,with the proviso that when no A blocks are present, then each B block comprises terminal regions that are rich in conjugated diene units and one or more non-terminal units that are rich in mono alkenyl arene units, and with the further proviso that when more than one A block is present, then each A block has a molecular weight of less than about 5000.

12. The oil composition of claim 11 wherein said mono alkenyl arene is styrene and said conjugated diene is selected from the group consisting of isoprene and butadiene.

13. The oil composition of claim 12 wherein said conjugated diene is butadiene, and wherein from about 15 to about 30 mol percent of the condensed butadiene units in block B have a 1,2-configuration.

14. The oil composition of claim 12 wherein said conjugated diene is butadiene, and wherein from about 18 to about 22 mol percent of the condensed butadiene units in block B have a 1,2-configuration.

15. The oil composition of claim 11 wherein said polymer block B has a mono alkenyl arene blockiness index of less than about 40 percent.

16. The oil composition of claim 12 wherein the polymer is an ABA polymer and each block B has a center region with a minimum ratio of butadiene units to styrene units.

17. The oil composition of claim 12 wherein the weight percent of styrene in each B block is between about 10 percent and about 50 percent, and the styrene blockiness index of each block B is less than about 10 percent, said styrene blockiness index being defined to be the proportion of styrene units in the block B having two styrene neighbors on the polymer chain.

18. The oil composition of claim 11 wherein said hydrogenated block copolymer has a general configuration (B)m, A-B, A-B-A, (A-B)n, (A-B-A)n, (A-Bn-A, (A-B-A)nX, (A-B)nX, (B-A-B)n, (B-A-B)nX or a mixture thereof, where n is an integer from 2 to about 60, X is coupling agent residue, and m is an integer from 1 to about 60.

19. The oil composition of claim 18 wherein said hydrogenated block polymer has the general configuration (B)m wherein each of the B blocks comprises terminal regions that are rich in conjugated diene units and one or more non-terminal regions that are rich in mono alkenyl arene.

20. The oil composition of claim 11 wherein said hydrogenated block copolymer is a S-EB/S type polymer, wherein the S block has a molecular weight from about 30,000 to about 50,000, the EB unit of the EB/S block has a molecular weight from about 50,000 to about 65,000, the S unit of the EB/S block has a molecular weight from about 30,000 to about 40,000, the EB/S block is selectively hydrogenated to remove at least 90% of the butadiene double bonds, the styrene content of the EB/S block is from about 30 to about 40 weight percent, the 1,2/1,4-butadiene ratio is from about 15/85 to about 30/70, and the total styrene content of the S-EB/S type polymer is from about 50 to about 65.

21. The oil composition of claim 11 further comprising at least one of an anti-corrosive additive, an antioxidant, a detergent, a pour point depressant or additional VI improvers that are different from said hydrogenated anionic block copolymer.

22. A polymeric concentrate for oil compositions comprising: at least 75% by weight of a base oil; andfrom 5% to 25% by weight of a hydrogenated block copolymer having at least one polymer block B and optionally at least one polymer block A, and wherein: a. prior to hydrogenation each A block is a mono alkenyl arene homopolymer block and each B block is a controlled distribution copolymer block of at least one conjugated diene and at least one mono alkenyl arene;b. subsequent to hydrogenation about 0-10% of the arene double bonds have been reduced, and at least about 90% of the conjugated diene double bonds have been reduced;c. each A block has a number average molecular weight between about 3,000 and about 60,000 and each B block has a number average molecular weight between about 20,000 and about 300,000;d. each B block comprises terminal regions adjacent to the A blocks that are rich in conjugated diene units and one or more regions not adjacent to the A blocks that are rich in mono alkenyl arene units;e. the total amount of mono alkenyl arene in the hydrogenated block copolymer is from about 20 percent weight to about 80 percent weight; andf. the weight percent of mono alkenyl arene in each B block is between about 10 percent and about 75 percent,with the proviso that when no A blocks are present, then each B block comprises terminal regions that are rich in conjugated diene units and one or more non-terminal units that are rich in mono alkenyl arene units, and with the further proviso that when more than one A block is present, then each A block has a molecular weight of less than about 5000.

23. The polymeric concentrate of claim 22 wherein said mono alkenyl arene is styrene and said conjugated diene is selected from the group consisting of isoprene and butadiene.

24. The polymeric concentrate of claim 23 wherein said conjugated diene is butadiene, and wherein from about 15 to about 30 mol percent of the condensed butadiene units in block B have a 1,2-configuration.

25. The polymeric concentrate of claim 23 wherein said conjugated diene is butadiene, and wherein from about 18 to about 22 mol percent of the condensed butadiene units in block B have a 1,2-configuration.

26. The polymeric concentrate of claim 22 wherein said polymer block B has a mono alkenyl arene blockiness index of less than about 40 percent.

27. The polymeric concentrate of claim 22 wherein the polymer is an ABA polymer and each block B has a center region with a minimum ratio of butadiene units to styrene units.

28. The polymeric concentrate of claim 22 wherein the weight percent of styrene in each B block is between about 10 percent and about 50 percent, and the styrene blockiness index of each block B is less than about 10 percent, said styrene blockiness index being defined to be the proportion of styrene units in the block B having two styrene neighbors on the polymer chain.

29. The polymeric concentrate of claim 22 wherein said hydrogenated block copolymer has a general configuration (B)m, A-B, A-B-A, (A-B)n, (A-B-A)n, (A-B)n-A, (A-B-A)nX, (A-B)nX, (B-A-B)n, (B-A-B)nX or a mixture thereof, where n is an integer from 2 to about 60, X is coupling agent residue, and m is an integer from 1 to about 60.

30. The polymeric concentrate of claim 29 wherein said hydrogenated block polymer has the general configuration (B)m wherein each of the B blocks comprises terminal regions that are rich in conjugated diene units and one or more non-terminal regions that are rich in mono alkenyl arene.

31. The polymeric concentrate of claim 22 wherein said hydrogenated block copolymer is a S-EB/S type polymer, wherein the S block has a molecular weight from about 30,000 to about 50,000, the EB unit of the EB/S block has a molecular weight from about 50,000 to about 65,000, the S unit of the EB/S block has a molecular weight from about 30,000 to about 40,000, the EB/S block is selectively hydrogenated to remove at least 90% of the butadiene double bonds, the styrene content of the EB/S block is from about 30 to about 40 weight percent, the 1,2/1,4-butadiene ratio is from about 15/85 to about 30/70, and the total styrene content of the S-EB/S type polymer is from about 50 to about 65.

32. The polymeric concentrate of claim 22 further comprising at least one of an anti-corrosive additive, an antioxidant, a detergent, a pour point depressant or additional VI improvers that are different from said hydrogenated anionic block copolymer.