DIBLOCK AND TRIBLOCK COPOLYMER CONCENTRATES FOR LUBRICATING OIL COMPOSITIONS

Abstract

A viscosity index improver (VII) or viscosity modifier (VM) concentrate comprising: from about 60 parts to about 95 parts of a diluent oil; and from about 5 parts to about 40 parts of star diblock and triblock copolymers characterized by the formula:

(D-PA-D)n-X and linear diblock and triblock copolymers characterized by the formula:

D-PA-D wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; D has a number average molecular weight of about 15,000 Daltons or less; a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; the concentrate comprises at least 50 wt % of the diluent oil and from about 6.0 wt. % to about 14.0 wt. % of the star and linear diblock and triblock copolymers. The diblock and triblock copolymers possess the ability to thicken in concentrates without gelation or slow flowing material, relatively uniformly across different types or Groups of base stocks/diluents, at high active ingredient concentrations and handling temperatures.

Claims

1. A viscosity index improver (VII) or viscosity modifier (VM) concentrate comprising: from about 60 parts to about 95 parts of a diluent oil; and from about 5 parts to about 40 parts of star diblock and triblock copolymers characterized by the formula: ##STR00023## and linear diblock and triblock copolymers characterized by the formula: ##STR00024## wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; wherein D has a number average molecular weight of about 15,000 Daltons or less; wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers are present in an amount effective to modify a lubricating kinematic viscosity at approximately 100 C. (KV100) of the concentrate; wherein the concentrate comprises at least 50 wt % of the diluent oil and the effective amount of the star diblock and triblock copolymers and linear diblock and triblock copolymers is such that the concentrate comprises from about 6.0 wt. % to about 14.0 wt. % of the star diblock and triblock copolymers and linear diblock and triblock copolymers; wherein a KV100 of the diluent oil is from about 2 cSt to about 40 cSt, and a KV100 of the concentrate is about 3000 cSt or less, and wherein the concentrate has a .sup.80 C. beaker pour of at least about 75% or a 25 C. tan of at least about 0.7, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.6, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20% as determined by ASTM D6278-98.

2. A concentrate according to claim 1, wherein the concentrate comprises from about 7.0 wt % to about 14 wt %, or from about 8.0 wt % to about 13 wt %, or from about 9.0 wt % to about 12 wt %, of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

3. A concentrate according to claim 1, wherein the KV100 of the concentrate is about 2500 cSt or less, or about 2000 cSt or less, or about 1500 cSt or less, or about 1000 cSt or less.

4. A concentrate according to claim 1, wherein D has a number average molecular weight from about 22,500 Daltons to about 52,500 Daltons, or from about 25,000 Daltons to about 50,000 Daltons, or from about 31,500 Daltons to about 47,500 Daltons; PA has a number average molecular weight from about 12,500 Daltons to about 32,500 Daltons, or from about 15,000 Daltons to about 30,000 Daltons, or from about 14,000 Daltons to about 18,000 Daltons; and D has a number average molecular weight of about 12,500 Daltons or less, or about 12,000 Daltons or less, or about 10,000 Daltons or less.

5. A concentrate according to claim 1, wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 3.0:1 or greater, or about 3.5:1 or greater, or about 4.0:1 or greater.

6. A concentrate according to claim 1, wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is greater than about 1.40:1, or greater than about 1.70:1, or greater than about 1.90:1.

7. A concentrate according to claim 1, wherein the star diblock and triblock copolymers have a total number average molecular weight of from about 100,000 Daltons to about 1,000,000 Daltons, or from about 200,000 Daltons to about 1,000,000 Daltons, or from about 400,000 Daltons to about 800,000 Daltons, or from about 500,000 Daltons to about 700,000 Daltons; and wherein the linear diblock and triblock copolymers have a total number average molecular weight of from about 25,000 Daltons to about 100,000 Daltons, or from about 40,000 Daltons to about 80,000 Daltons, or from about 50,000 Daltons to about 70,000 Daltons.

8. A concentrate according to claim 1, wherein PA is present in the star diblock and triblock copolymers and linear diblock and triblock copolymers in an amount from about 20 wt. % to about 35 wt. %, or from about 22.5 wt. % to about 32.5 wt. %, or from about 25 wt. % to about 30 wt. %, based on the total weight of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

9. A concentrate according to claim 1, wherein the KV100 of the concentrate is from about 100 cSt to about 3000 cSt, or from about 100 cSt to about 2500 cSt, or from about 100 cSt to about 2000 cSt.

10. A concentrate according to claim 1, wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 65%, or greater than about 80%, or greater than about 90%.

11. A concentrate according to claim 1, wherein the D and D dienes each individually comprise butadiene, isoprene, or mixtures of butadiene and isoprene in any weight ratio, but are not identical to each other in molecular weight, in chemical composition, or both, and wherein the D and D blocks are substantially hydrogenated after polymerization.

12. A concentrate according to claim 1, wherein at least one of diene blocks D and D, or each of diene blocks D and D, are random isoprene/butadiene copolymer blocks having isoprene and butadiene in any weight ratio, or isoprene polymer blocks, or butadiene polymer blocks; or wherein diene block D is a random isoprene/butadiene copolymer block having isoprene and butadiene in any weight ratio, or isoprene polymer block, or butadiene polymer block, and diene block D is a butadiene polymer block.

13. A concentrate according to claim 1, wherein diene blocks D and D are hydrogenated to remove at least about 80%, or at least 90%, or at least 95%, of unsaturations, or are fully hydrogenated.

14. A concentrate according to claim 1, wherein the polyalkenyl coupling agent is selected from the group consisting of benzene, toluene, xylene, anthracene, naphthalene, and durene, which are substituted with at least two alkenyl groups, attached directly thereto; divinyl benzene, trivinyl benzene, tetravinyl benzene, divinyl xylene, trivinyl xylene, tetravinyl ortho-xylene, tetravinyl meta-xylene, tetravinyl para-xylene, divinyl naphthalene, divinyl ethyl benzene, divinyl biphenyl, diisobutenyl benzene, diisopropenyl benzene, and diisopropenyl biphenyl.

15. A concentrate according to claim 1, which is formulated into a lubricating oil composition having a viscosity grade of SAE 25 W-X, SAE 20 W-X, SAE 15 W-X, SAE 10 W-X, SAE 5 W-X, or SAE 0 W-X, where X represents any one of 8, 12, 16, 20, 30, 40, 50, and 60.

16. A concentrate according to claim 1, wherein the concentrate has a .sup.80 C. beaker pour of at least about 85%, or at least about 90%; a 25 C. tan of at least about 1.0, or at least about 1.5, or at least about 2.0; a thickening efficiency (TE) in a Group III diluent oil of at least about 1.7, or at least about 1.8; and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 15%, or less than about 10%, as determined by ASTM D6278-98.

17. A concentrate according to claim 1, wherein the diluent oil comprises a Group I, Group II, Group III, Group IV base stock, or any mixture thereof.

18. A concentrate according to claim 1, further comprising one or more of an ashless dispersant, a detergent, an anti-wear agent, an antioxidant, a corrosion inhibitor, a friction modifier, an antifoamant, a seal-swelling control agent, or a combination thereof.

19. A method of modifying the kinematic viscosity at approximately 100 C. (KV100) of the viscosity index improver (VII) or viscosity modifier (VM) concentrate of claim 1, the method comprising adding to the concentrate an effective amount of the star diblock and triblock copolymers characterized by the formula: ##STR00025## and the linear diblock and triblock copolymers characterized by the formula: ##STR00026## wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; wherein D has a number average molecular weight of about 15,000 Daltons or less; wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers are present in an amount effective to modify a lubricating kinematic viscosity at approximately 100 C. (KV100) of the concentrate; wherein the concentrate comprises at least 50 wt % of the diluent oil and the effective amount of the star diblock and triblock copolymers and linear diblock and triblock copolymers is such that the concentrate comprises from about 6.0 wt. % to about 14.0 wt. % of the star diblock and triblock copolymers and linear diblock and triblock copolymers; wherein a KV100 of the diluent oil is from about 2 cSt to about 40 cSt, and a KV100 of the concentrate is about 3000 cSt or less, and wherein the concentrate has a .sup.80 C. beaker pour of at least about 75% or a 25 C. tan of at least about 0.7, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.6, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20% as determined by ASTM D6278-98.

20. A lubricating oil composition comprising a major amount of oil of lubricating viscosity, and the viscosity index improver (VII) or viscosity modifier (VM) concentrate of claim 1, in an amount effective to modify the viscosity index of the lubricating oil composition.

21. A lubricating oil composition according to claim 20, further comprising one or more of an ashless dispersant, a detergent, an anti-wear agent, an antioxidant, a corrosion inhibitor, a friction modifier, an antifoamant, a seal-swelling control agent, or a combination thereof.

22. A lubricating oil composition according to claim 20, having a high temperature, high shear (HTHS) viscosity as measured by ASTM D4683 at 150 C. of from greater than about 1.7 mPa.Math.s, to less than about 6.5 mPa.Math.s.

23. A lubricating oil composition according to claim 20, having improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers having a coupling efficiency of a polyalkenyl coupling agent and arms less than about 70%, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1; or having improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers and linear diblock and triblock copolymers wherein PA has a number average molecular weight less than about 10,000 Daltons, or wherein PA is present in the star diblock and triblock copolymers and linear diblock and triblock copolymers in an amount less than about 20 wt. %, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1.

24. A lubricating oil composition according to claim 20, having a viscosity grade of SAE 25 W-X, SAE 20 W-X, SAE 15 W-X, SAE 10 W-X, SAE 5 W-X, or SAE 0 W-X, where X represents any one of 8, 12, 16, 20, 30, 40, 50, and 60.

25. A lubricating oil composition according to claim 20, for passenger car, heavy-duty diesel, marine diesel engines, functional fluids, and manual/automatic transmission fluids.

26. Polymers suitable for use as a viscosity index improver (VII) or viscosity modifier (VM) for a lubricating oil composition comprising star diblock and triblock copolymers characterized by the formula: ##STR00027## and linear diblock and triblock copolymers characterized by the formula: ##STR00028## wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; wherein D has a number average molecular weight of about 15,000 Daltons or less; wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; and wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 shows VM and VII concentrates, the KV100 of each concentrate, as well as the molecular weights of the block copolymer segments of the triblock arm star copolymers, the polymer composition, the base stock diluent, the active ingredient concentration, and gel formation, in accordance with the Examples.

[0040] FIG. 2 shows VM and VII concentrates, the flowability of each concentrate, as well as the molecular weights of the block copolymer segments of the triblock arm star copolymers, the polymer composition, the base stock diluent, the active ingredient concentration, beaker pour testing (concentrate poured out at 40 C., 60 C. and 80 C.), and a tan value (measured at 25 C.), in accordance with the Examples.

[0041] FIG. 3 shows VM and VII concentrates, the copolymer thickening efficiency (TE) in Group III testing oils at 1% and 1.5% polymer treat rate, as well as the molecular weights of the block copolymer segments of the triblock arm star copolymers, the polymer composition, the active ingredient concentration, coupling percent, in accordance with the Examples.

[0042] FIG. 4 shows a modeling prediction of viscometrics for 5 W-30 and 5 W-40 with a passenger car motor oil (PCMO) additive package in Group III oils, in accordance with the Examples.

[0043] FIG. 5 shows viscometrics for 0 W-30 3.5 cP with a passenger car motor oil (PVMO) additive package in Yubase4+ and PAO, in accordance with the Examples.

[0044] FIG. 6 shows viscometrics for 0 W-40 3.5 cP with a passenger car motor oil (PCMO) additive package in Yubase, Yubase4+, and PAO, in accordance with the Examples.

[0045] FIG. 7 shows shear stability index testing (known as the Kurt-Orban (KO) or DIN bench 15 test) results of triblock linear and star copolymers in a 4 cSt oil blended with Group III base stocks, in accordance with the Examples.

[0046] FIG. 8 graphically depicts viscosity loss of polymer solutions in 30, 90, and 120 cycle shear stability index (KO) shearing, in accordance with the Examples.

[0047] FIG. 9 shows shear stability index (KO) testing results of 1.7% triblock star copolymers in a 4 cSt oil blended with Group I base stocks, in accordance with the Examples.

[0048] FIG. 10 graphically depicts viscosity loss of polymer solutions in 30, 90, and 120 cycle shear stability index (KO) shearing, in accordance with the Examples.

[0049] FIG. 11 shows viscometric modeling prediction and testing data of linear and star triblock copolymers in a SAE API CK4 5 W-30 heavy duty diesel (HDD) formulation with HDD additive package in Yubase4 and Yubase6, in accordance with the Examples.

[0050] FIG. 12 shows SAE HDD 5 W-30 formulations and properties of lubricating oil compositions of this disclosure having star triblock copolymer at different coupling efficiencies and linear triblock copolymer (with no coupling), in accordance with the Examples.

[0051] FIG. 13 graphically depicts Haake testing for star triblock copolymer and star arm with different coupling efficiency with 5 W-30 having 9% carbon black, in accordance with the Examples.

[0052] FIG. 14 graphically depicts Haake testing for high coupling efficiency star triblock copolymer in oils with 9% carbon black, in particular, 5 W-30 oils having 9% carbon black, in accordance with the Examples.

[0053] FIG. 15 graphically depicts Haake testing for high coupling efficiency star triblock copolymer in oils with 12% carbon black, in particular, 5 W-30 oils having 12% carbon black, in accordance with the Examples.

DETAILED DESCRIPTION

[0054] Star diblock and triblock copolymers of the present disclosure can be characterized by the formula:

##STR00009## [0055] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene but which is typically not identical to D (in molecular weight, in chemical composition, or both); n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25, or from about 5 to about 20; [0056] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0057] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0058] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0059] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0060] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; and [0061] wherein the star diblock and triblock copolymer has a coupling efficiency greater than about 50%.

[0062] Linear diblock and triblock copolymers of the present disclosure can be characterized by the formula:

##STR00010## [0063] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene but which is typically not identical to D (in molecular weight, in chemical composition, or both); [0064] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0065] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0066] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0067] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; and [0068] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater.

[0069] VM or VII concentrates of the present disclosure may be characterized by a lubricating kinematic viscosity at approximately 100 C. (KV100) and may contain: from about 60 parts to about 95 parts (e.g., from about 60 parts to about 90 parts) of a diluent oil; and from about 5 parts to about 40 parts (e.g., from about 10 parts to about 40 parts) of star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure. The diluent oil may advantageously comprise a majority of the concentrate (i.e., the concentrate comprises more than 50 wt % of the diluent oil component). Further, the star diblock and triblock copolymers and linear diblock and triblock copolymers may advantageously be present in an amount effective to modify the KV100 of the concentrate.

[0070] For example, the effective amount may be such that the concentrate may include at least 6.0 wt % of the star diblock and triblock copolymers and linear diblock and triblock copolymers (e.g., at least about 6.25 wt %, at least about 6.5 wt %, at least about 6.75 wt %, at least about 7.0 wt %, at least about 7.25 wt %, at least about 7.5 wt %, at least about 7.75 wt %, at least about 8.0 wt %, at least about 8.25 wt %, at least about 8.5 wt %, at least about 8.75 wt %, at least 9.0 wt %, at least about 9.25 wt %, at least 9.5 wt %, at least about 9.75 wt %, at least 10.0 wt %, at least about 10.25 wt %, at least about 10.5 wt %, at least about 10.75 wt %, at least about 11.0 wt %, at least about 11.25 wt %, at least about 11.5 wt %, at least about 11.75 wt %, at least about 12.0 wt %, at least about 12.25 wt %, at least 12.5 wt %, at least about 12.75 wt %, at least about 13.0 wt %, at least about 13.25 wt %, at least about 13.5 wt %, at least about 13.75 wt %, at least about 14.0 wt %, at least about 14.25 wt %, at least about 14.5 wt %, at least about 14.75 wt %, at least about 15.0 wt %). Preferably, the concentrate may include from about 7.0 wt % to about 14 wt %, or from about 8.0 wt % to about 13 wt %, or from about 9.0 wt % to about 12 wt %, of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

[0071] Additionally or alternatively, the effective amount may be such that the concentrate may include up to about 40 wt % of the star diblock and triblock copolymers and linear diblock and triblock copolymers (e.g., up to about 38 wt %, up to about 35 wt %, up to about 33 wt %, up to about 30 wt %, up to about 28 wt %, up to about 25 wt %, up to about 23 wt %, up to about 20 wt %, up to about 18 wt %, up to about 17 wt %, up to about 16 wt %, up to about 15 wt %, up to about 14 wt %, up to about 13 wt %, up to about 12 wt %, up to about 11 wt %, up to about 9.9 wt %, up to about 9.7 wt %, up to about 9.5 wt %, up to about 9.3 wt %, up to about 9.0 wt %, up to about 8.8 wt %, up to about 8.5 wt %, up to about 8.3 wt %, up to about 8.0 wt %, up to about 7.8 wt %, or up to about 7.5 wt %). In particular, the concentrate may include at least 6.0 wt %, at least 9.5 wt %, from 6.0 wt % to 14 wt %, from 6.5 wt % to 14 wt %, or from 9.5 wt % to 14 wt %, of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

[0072] The KV100 of the concentrate, containing both the diluent oil component and the star diblock and triblock copolymers and linear diblock and triblock copolymers, may advantageously be about 3000 cSt or less (e.g., about 2500 cSt or less, about 2000 cSt or less, about 1900 cSt or less, about 1800 cSt or less, about 1700 cSt or less, about 1600 cSt or less, about 1550 cSt or less, about 1500 cSt or less, about 1450 cSt or less, about 1400 cSt or less, about 1350 cSt or less, about 1300 cSt or less, about 1250 cSt or less, about 1200 cSt or less, about 1150 cSt or less, about 1100 cSt or less, about 1050 cSt or less, about 1000 cSt or less, about 950 cSt or less, about 900 cSt or less, about 850 cSt or less, about 800 cSt or less, about 750 cSt or less, about 700 cSt or less, or about 650 cSt or less). Optionally, the KV100 of the concentrate, containing both the diluent oil component and the star diblock and triblock copolymers and linear diblock and triblock copolymers, may be at least about 100 cSt (e.g., at least about 200 cSt, at least about 300 cSt, at least about 400 cSt, at least about 500 cSt, at least about 550 cSt, at least about 600 cSt, at least about 650 cSt, at least about 700 cSt, at least about 750 cSt, at least about 800 cSt, at least about 850 cSt, at least about 900 cSt, at least about 950 cSt, at least about 1000 cSt, at least about 1050 cSt, at least about 1100 cSt, at least about 1150 cSt, at least about 1200 cSt, or at least about 1250 cSt). In particular, the KV100 of the concentrate may be about 3000 cSt or less, about 2000 cSt or less, about 1600 cSt or less, from 100 cSt to 3000 cSt, from 100 cSt to 2500 cSt, from 100 cSt to 1600 cSt, from 1000 cSt to 2000 cSt, or from 500 cSt to 2000 cSt.

[0073] The D and D blocks derived from diene may be similar or different (in molecular weight, in chemical composition, or both), but each D and D may individually comprise butadiene, isoprene, and mixtures thereof. In an embodiment, diene block D is a random isoprene/butadiene copolymer block, or isoprene polymer block, and diene block D is a butadiene polymer block. In some embodiments, the D and D diene blocks may be mostly or substantially derived from isoprene monomers. For example, the D and D dienes may each individually comprise at least about 85 wt % isoprene (e.g., at least about 88 wt %, at least about 90 wt %, at least about 92 wt %, at least about 94 wt % at least about 96 wt %, at least about 97 wt %, at least about 98 wt %, at least about 99 wt %, at least about 99.5 wt %, or at least about 99.9 wt %) and/or not more than about 14 wt % butadiene (e.g., not more than about 12 wt %, not more than about 10 wt %, not more than about 8 wt %, not more than about 6 wt %, not more than about 4 wt %, not more than about 3 wt %, not more than about 2 wt %, not more than about 1 wt %, not more than about 0.5 wt %, or not more than about 0.1 wt %). In such embodiments, in particular, the D and D dienes may each individually comprise at least about 97 wt % isoprene and/or not more than about 3 wt % butadiene. Blocks D and D may advantageously be hydrogenated to remove at least about 80% (e.g., at least about 85%, at least about 90%, or at least about 95%) of polymerized diene unsaturations, and may be substantially or fully hydrogenated, typically after polymerization.

[0074] In other embodiments, at least one (or in some cases each) of diene blocks D and D may be copolymer blocks derived from mixed diene monomer (e.g., copolymer blocks of isoprene and butadiene in any weight ratio). In certain embodiments, from about 65 wt % to about 95 wt % of the incorporated monomer units are from isoprene and from about 5 wt %, up to about 35 wt % of the incorporated monomer units are from butadiene, and wherein at least about 80 wt % (or at least 90 wt %) of butadiene is incorporated in a 1,4-configuration. In certain such embodiments, at least about 15 wt % of the incorporated monomer units may be butadiene monomer units and/or no greater than about 25 wt % of the incorporated monomer units may advantageously be butadiene monomer units. In such embodiments, at least one (or in some cases each) of diene blocks D and D may be random copolymer blocks.

[0075] Isoprene monomers used as the precursors of the star diblock and triblock copolymer and linear diblock and triblock copolymers of the present disclosure can be incorporated into the diblock and triblock copolymer in either a 1,4- or 3,4-configuration, or as a mixture thereof. Preferably, the majority (i.e., greater than 50 wt %) of the isoprene may be incorporated into each individual block/copolymer as 1,4-units, e.g., greater than about 60 wt %, greater than about 70 wt %, greater than about 80 wt %, greater than about 90 wt %, greater than about 95 wt %, greater than about 97 wt %, greater than about 98 wt %, or greater than about 99 wt %, up to approximately 100 wt %. For example, from about 55 wt % to about 100 wt % (such as from about 60 wt % to about 100 wt %, from about 65 wt % to about 100 wt %, from about 70 wt % to about 100 wt %, from about 75 wt % to about 100 wt %, from about 80 wt % to about 100 wt %, from about 85 wt % to about 100 wt %, from about 90 wt % to about 100 wt %, from about 95 wt % to about 100 wt %, from about 97 wt % to about 100 wt %, from about 98 wt % to about 100 wt %, or from about 99 wt % to about 100 wt %) of the isoprene units may be incorporated into each individual block/copolymer in a 1,4-configuration. An excessive amount of polybutadiene, particularly polybutadiene having a 1,2-configuration, in the D and/or D diene blocks can have an adverse effect on low temperature pumpability properties.

[0076] In an embodiment, the D and D blocks derived from diene may be similar or different (in molecular weight, in chemical composition, or both), but each D and D may individually comprise butadiene, isoprene, or mixtures of butadiene and isoprene in any weight ratio. In an embodiment, isoprene monomers only can be used as the precursors of the star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure. In another embodiment, butadiene monomers only can be used as the precursors of the star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure. In yet another embodiment, a mixture of isoprene monomers and butadiene monomers in any weight ratio can be used as the precursors of the star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure.

[0077] In a particular embodiment, the D block may exhibit a number average molecular weight from about 20,000 Daltons to about 45,000 Daltons (e.g., from about 22,500 Daltons to about 42,500 Daltons, or from about 25,000 Daltons to about 40,000 Daltons, or from about 25,000 Daltons to about 35,000 Daltons, or from about 25,000 Daltons to about 30,000 Daltons), and the D block may exhibit a number average molecular weight of about 15,000 Daltons or less (e.g., about 12,500 Daltons or less, or about 12,000 Daltons or less, or about 10,000 Daltons or less, or about 8,000 Daltons or less, or about 6,000 Daltons or less, or about 4,000 Daltons or less, or about 2,000 Daltons or less).

[0078] Alternatively, the D block may exhibit a number average molecular weight from about 0 Daltons to about 15,000 Daltons, or from about 0 Daltons to about 12,500 Daltons, or from about 0 Daltons to about 12,000 Daltons, or from about 0 Daltons to about 10,000 Daltons, or from about 0 Daltons to about 8,000 Daltons, or from about 0 Daltons to about 6,000 Daltons, or from about 0 Daltons to about 4,000 Daltons, or from about 0 Daltons to about 2,000 Daltons.

[0079] In the aforementioned particular embodiment, the PA block may exhibit a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons, e.g., from about 12,500 Daltons to about 32,500 Daltons, from about 15,000 Daltons to about 30,000 Daltons, from about 14,000 Daltons to about 18,000 Daltons, from about 10,000 Daltons to about 34,000 Daltons, from about 10,000 Daltons to about 32,000 Daltons, from about 10,000 Daltons to about 30,000 Daltons, from about 10,000 Daltons to about 25,000 Daltons, from about 12,000 Daltons to about 35,000 Daltons, from about 12,000 Daltons to about 30,000 Daltons, from about 12,000 Daltons to about 27,500 Daltons, from about 12,000 Daltons to about 25,000 Daltons, from about 12,000 Daltons to about 22,500 Daltons, from about 12,000 Daltons to about 20,000 Daltons, from about 15,000 Daltons to about 35,000 Daltons, from about 15,000 Daltons to about 30,000 Daltons, from about 15,000 Daltons to about 27,500 Daltons, from about 15,000 Daltons to about 25,000 Daltons, from about 15,000 Daltons to about 22,500 Daltons, from about 15,000 Daltons to about 20,000 Daltons, from about 20,000 Daltons to about 70,000 Daltons, from about 20,000 Daltons to about 60,000 Daltons, from about 20,000 Daltons to about 35,000 Daltons, from about 20,000 Daltons to about 32,500 Daltons, from about 20,000 Daltons to about 30,000 Daltons, from about 25,000 Daltons to about 35,000 Daltons, from about 25,000 Daltons to about 30,000 Daltons. In particular, the PA block may exhibit a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons, from about 12,500 Daltons to about 32,500 Daltons, from about 15,000 Daltons to about 30,000 Daltons, or from about 14,000 Daltons to about 18,000 Daltons.

[0080] Additionally or alternatively, in the star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure, PA may be present in an amount from about 20 wt. % to about 35 wt. %, or from about 25 wt. % to about 30 wt. %, based on the total weight of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

[0081] Additionally or alternatively, in the star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure, a ratio of PA block number average molecular weight to a sum of D+D block number average molecular weights may be from about 0.25 to about 0.50, e.g., from about 0.25 to about 0.45, from about 0.25 to about 0.40, from about 0.25 to about 0.35, from about 0.25 to about 0.30, from about 0.30 to about 0.50, from about 0.30 to about 0.45, from about 0.30 to about 0.40, from about 0.30 to about 0.35, from about 0.35 to about 0.50, from about 0.35 to about 0.45, from about 0.35 to about 0.40, from about 0.40 to about 0.50, from about 0.40 to about 0.45, or from about 0.45 to about 0.50.

[0082] Additionally or alternatively, in the star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure, a ratio of PA block number average molecular weight to D block number average molecular weight may be about 1.4:1 or greater, or about 1.5:1 or greater, or about 1.6:1 or greater, or about 1.7:1 or greater, or about 1.8:1 or greater, or about 1.9:1 or greater, or about 2.0:1 or greater, or about 3.0:1 or greater, or about 4.0:1 or greater, or about 6.0:1 or greater, or about 8.0:1 or greater.

[0083] Further additionally or alternatively, in star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure, there may be a relationship between number average molecular weights of the diene blocks. For example, in an embodiment, a ratio between the D block number average molecular weight and the D block number average molecular weight may be 3.0:1 or greater. However, in another embodiment, a ratio between the D block number average molecular weight and the D block number average molecular weight may be from about 3.5:1 or greater. In yet another embodiment, a ratio between the D block number average molecular weight and the D block number average molecular weight may be about 4.0:1 or greater.

[0084] The term number average molecular weight, as used herein, should be understood to refer to the absolute number average molecular weight (Mn) as measured by Gel Permeation Chromatography (GPC, also known as Size Exclusion Chromatography, or SEC) in tetrahydrofuran (THF) eluent at approximately 40 C. and using relatively monodisperse polystyrene standards to get the relative Mn, and then applying a correlation correction factor from light scanning to get the absolute Mn. Molecular weights (e.g., number average molecular weights) of the diene blocks, D and D, are reported herein as measured prior to any hydrogenation that may be done post-polymerization.

[0085] Suitable monoalkenyl arene monomers include monovinyl aromatic compounds, such as styrene, monovinylnaphthylene, as well as the alkylated derivatives thereof, such as o-, m- and p-methylstyrene, alpha-methyl styrene, ethylstyrenes (in particular p-ethylstyrene), propylstyrenes (in particular p-isopropylstyrene), and tertiary butylstyrenes (in particular para-t-butylstyrene). In particular, the monoalkenyl arene may comprise or be styrene.

[0086] Star diblock and triblock polymers of the present disclosure can have from 4 to about 25 arms (n=about 4 to about 25), preferably from about 10 to about 20 arms. Star diblock and triblock copolymers of the present disclosure may have a total number average molecular weight (additive combination of number average molecular weights of D, PA, and D blocks and X nucleus of a coupling agent) from about 25,000 Daltons to about 1,000,000 Daltons, e.g., from about 100,000 Daltons to about 1,000,000 Daltons, or from about 400,000 Daltons to about 800,000 Daltons, or from about 500,000 Daltons to about 700,000 Daltons.

[0087] Linear diblock and triblock copolymers of the present disclosure may have a total number average molecular weight (additive combination of number average molecular weights of D, PA, and D blocks) from about 25,000 Daltons to about 1,000,000 Daltons, e.g., from about 40,000 Daltons to about 500,000 Daltons, or from about 50,000 Daltons to about 100,000 Daltons.

[0088] The linear diblock and triblock copolymers and diblock and triblock arms of the star diblock and triblock copolymers can be formed as living polymers via anionic polymerization, in solution, in the presence of an anionic initiator, as described, for example, in U.S. Pat. Nos. RE27,145 and 4,116,917. Exemplary initiators may include or be a (mono) lithium hydrocarbon. Suitable lithium hydrocarbons may include unsaturated compounds such as allyl lithium, methallyl lithium; aromatic compounds such as phenyllithium, the tolyllithiums, the xylyllithiums and the naphthyllithiums, and in particular, the alkyl lithiums such as methyllithium, ethyllithium, propyllithium, butyllithium, amyllithium, hexyllithium, 2-ethylhexyllithium, and n-hexadecyllithium. In particular, the initiator may comprise or be secondary-butyllithium. The initiator(s) may be added to the polymerization mixture in two or more stages, optionally together with additional monomer.

[0089] The linear diblock and triblock copolymers and diblock and triblock arms of the star diblock and triblock copolymers can, and may preferably, be prepared by step-wise polymerization of the monomers, e.g., polymerizing one of the two diene blocks, followed by the addition of the other monomer(s) (specifically including or being monoalkenyl arene monomer), followed by the polymerization of the second of the two diene blocks to form a living polymer having the formula polydiene block-poly(alkenyl arene) block-polydiene block.

[0090] If either or both of D and D are desired to be random diene copolymers, such as polyisoprene/polybutadiene copolymers, the living polydiene copolymer blocks, in the absence of the proper control of the polymerization will, as described in U.S. Pat. No. 7,163,913, not be a random copolymer and will instead comprise a polybutadiene block, a tapered segment containing both butadiene and isoprene addition product, and a polyisoprene block. To prepare a random copolymer, the more reactive butadiene monomer may be added gradually to the polymerization reaction mixture containing the less reactive isoprene such that the molar ratio of the monomers in the polymerization mixture is maintained at the required level. It is also possible to achieve the required randomization by gradually adding a mixture of the monomers to be copolymerized to the polymerization mixture. Living random copolymers may also be prepared by carrying out the polymerization in the presence of a so-called randomizer. Randomizers may include or be polar compounds that do not substantially deactivate the polymerization process and that tend to randomize the manner in which the monomers are incorporated into to the polymer chain. Suitable randomizers may include, but are not necessarily limited to, tertiary amines, such as trimethylamine, triethylamine, dimethylamine, tri-n-propylamine, tri-n-butylamine, dimethylaniline, pyridine, quinoline, N-ethyl-piperidine, N-methylmorpholine; thioethers, such as dimethyl sulfide, diethyl sulfide, di-n-propyl sulfide, di-n-butyl sulfide, methyl ethyl sulfide; and in particular, ethers such as dimethyl ether, methyl ether, diethyl ether, di-n-propyl ether, di-n-butyl ether, di-octyl ether, di-benzyl ether, di-phenyl ether, anisole, 1,2-dimethyloxyethane, o-dimethyloxybenzene, and cyclic ethers, such as tetrahydrofuran.

[0091] Even with controlled monomer addition and/or the use of a randomizer, the initial and terminal portions of the polymer chains may have greater than a random amount of polymer derived from the more reactive and less reactive monomer, respectively. Therefore, for the purpose of this disclosure, the term random copolymer means a polymer chain, or a polymer block, the preponderance of which (e.g., greater than 80%, such as greater than 90% or greater than 95%) results from the random addition of comonomer materials. In an embodiment, the D and D blocks derived from diene may be mixtures of butadiene and isoprene in any weight ratio.

[0092] The solvents in which the living polymers can be formed may include relatively inert liquid solvents, such as hydrocarbons, e.g., aliphatic hydrocarbons such as pentane, hexane, heptane, octane, 2-ethylhexane, nonane, decane, cyclohexane, methylcyclohexane, or the like, or combinations thereof, and/or aromatic hydrocarbons, e.g., benzene, toluene, ethylbenzene, the xylenes, diethylbenzenes, propylbenzenes, or the like, or combinations thereof. Cyclohexane is particularly exemplary. Mixtures of hydrocarbons, e.g., lubricating oils, may additionally or alternatively be used.

[0093] The temperature at which the living polymerization is conducted may be varied within a wide range, such as from about 50 C. to about 150 C., such as from about 20 C. to about 80 C. The reaction may suitably be carried out in a relatively inert atmosphere, such as under nitrogen, and may optionally be carried out under pressure, e.g., a pressure from about 0.5 bar to about 10 bars.

[0094] The concentration of the initiator used to prepare the living polymer may also vary within a wide range and may advantageously be driven by the desired molecular weight of the living polymer.

[0095] To provide a star polymer, the living polymers formed via the foregoing process may be reacted in an additional reaction step, with a polyalkenyl coupling agent. Polyalkenyl coupling agents capable of forming star polymers have been known for a number of years and are described, for example, in U.S. Pat. No. 3,985,830. Polyalkenyl coupling agents are conventionally compounds having at least two non-conjugated alkenyl groups. Such groups are usually attached to the same or different electron-withdrawing moiety e.g., an aromatic nucleus. Such compounds have alkenyl groups that are capable of independent reaction with different living polymers and in this respect are different from conventional conjugated diene polymerizable monomers such as butadiene, isoprene, etc. Pure or technical grade polyalkenyl coupling agents may be used. Such compounds may be aliphatic, aromatic, or heterocyclic. Examples of aliphatic compounds include the polyvinyl and polyallyl acetylene, diacetylenes, phosphates and phosphates as well as dimethacrylates, e.g., ethylene dimethylacrylate. Examples of suitable heterocyclic compounds include divinyl pyridine and divinyl thiophene.

[0096] The preferred coupling agents are the polyalkenyl aromatic compounds and most preferred are the polyvinyl aromatic compounds. Examples of such compounds include those aromatic compounds, e.g., benzene, toluene, xylene, anthracene, naphthalene and durene, which are substituted with at least two alkenyl groups, preferably attached directly thereto. Specific examples include the polyvinyl benzenes e.g., divinyl, trivinyl and tetravinyl benzenes; divinyl, trivinyl and tetravinyl ortho-, meta- and para-xylenes, divinyl naphthalene, divinyl ethyl benzene, divinyl biphenyl, diisobutenyl benzene, diisopropenyl benzene, and diisopropenyl biphenyl. The preferred aromatic compounds are those represented by the formula A-(CHCH.sub.2).sub.x wherein A is an optionally substituted aromatic nucleus and x is an integer of at least 2. Divinyl benzene, in particular meta-divinyl benzene, is the most preferred aromatic compound. Pure or technical grade divinyl benzene (containing other monomers e.g., styrene and ethyl styrene) may be used. The coupling agents may be used in admixture with small amounts of added monomers which increase the size of the nucleus, e.g., styrene or alkyl styrene. In such a case, the nucleus can be described as a poly(dialkenyl coupling agent/monoalkenyl aromatic compound) nucleus, e.g., a poly(divinylbenzene/monoalkenyl aromatic compound) nucleus.

[0097] The polyalkenyl coupling agent should be added to the living polymer after the polymerization of the monomers is substantially complete, i.e., the agent should be added only after substantially all the monomer has been converted to the living polymers.

[0098] The amount of polyalkenyl coupling agent added may vary within a wide range, but preferably, at least 0.5 mole of the coupling agent is used per mole of unsaturated living polymer. Amounts of from about 1 to about 15 moles, preferably from about 1.5 to about 5 moles per mole of living polymer are preferred. The amount, which can be added in two or more stages, is usually an amount sufficient to convert at least about 80 wt. % to 85 wt. % of the living polymer into star-shaped polymer.

[0099] The coupling reaction can be carried out in the same solvent as the living polymerization reaction. The coupling reaction can be carried out at temperatures within a broad range, such as from 0 C. to 150 C., preferably from about 20 C. to about 120 C. The reaction may be conducted in an inert atmosphere, e.g., nitrogen, and under pressure of from about 0.5 bar to about 10 bars.

[0100] The coupling efficiency of the polyalkenyl coupling agent and diblock and triblock arms of the star copolymer is greater than about 50%, or greater than about 60%, or greater than about 70%, or greater than about 80%, or greater than about 90%.

[0101] The resulting linear and star shaped copolymers can then be hydrogenated using any suitable means. A hydrogenation catalyst may be used, e.g., a copper or molybdenum compound. Catalysts containing noble metals, or noble metal-containing compounds, can additionally or alternatively be used. Exemplary hydrogenation catalysts contain a non-noble metal or a non-noble metal-containing compound of Group VIII of the Periodic Table of Elements, e.g., iron, cobalt, and/or particularly nickel. Specific but non-exclusive examples of hydrogenation catalysts may include Raney nickel and nickel on kieselguhr. Particularly suitable hydrogenation catalysts may be those obtained by causing metal hydrocarbyl compounds to react with organic compounds of any of the group VIII metals iron, cobalt, and/or nickel, the latter compounds containing at least one organic compound that is attached to the metal atom via an oxygen atom as described, for example, in GB Patent No. 1,030,306. Preference may be given, in certain situations, to hydrogenation catalysts obtained by causing an aluminum trialkyl (e.g., aluminum triethyl (Al(Et.sub.3)) or aluminum triisobutyl) to react with a nickel salt of an organic acid (e.g., nickel diisopropyl salicylate, nickel naphthenate, nickel 2-ethyl hexanoate, nickel di-tert-butyl benzoate, nickel salts of saturated monocarboxylic acids obtained by reaction of olefins having from 4 to 20 carbon atoms in the molecule with carbon monoxide and water in the presence of acid catalysts, etc.) or with nickel enolates or phenolates (e.g., nickel acet(on)ylacetonate, the nickel salt of butylacetophenone, etc.). Suitable hydrogenation catalysts should be well known to those skilled in the art, and the foregoing list(s) is (are) not necessarily intended to be exhaustive.

[0102] The hydrogenation of the block copolymers of the present disclosure may be suitably conducted, e.g., in solution, such as in a solvent which is relatively or substantially inert during the hydrogenation reaction. Saturated hydrocarbons and/or mixtures of saturated hydrocarbons may be suitable solvents. Advantageously, the hydrogenation solvent may be the same as the solvent in which polymerization is conducted, or may be miscible with the solvent in which polymerization is conducted (e.g., containing one or more components that are the same as in the polymerization solvent). Typically, when a hydrogenation process is performed, at least 50 mol %, e.g., at least 70 mol %, at least 80 mol %, at least 90 mol %, at least 95 mol %, at least 99 mol %, at least 99.5 mol %, at least 99.9 mol %, or substantially all, of the original olefinic unsaturation may be hydrogenated in the process.

[0103] Additionally or alternatively, the star diblock and triblock copolymers and linear diblock and triblock copolymers can be selectively hydrogenated such that the olefin saturations are hydrogenated as above, while the aromatic unsaturations are hydrogenated to a lesser extent. In certain embodiments, less than 15% (e.g., less than 10% or less than 5%) of the aromatic unsaturations may be hydrogenated during the process. Selective hydrogenation techniques are also well known to those of ordinary skill in the art and are described, for example, in U.S. Pat. Nos. 3,595,942, RE 27,145, and 5,166,277.

[0104] The polymers may then be recovered, e.g., as a solid or in concentrated liquid form, from the solvent in which it is hydrogenated by any convenient means, such as by evaporating the solvent. Alternatively, an extractant such as an oil (e.g., lubricating oil) may be added to the solution, and the solvent stripped off from the mixture so formed to provide a concentrate. Suitable concentrates may contain from about 3 wt % to about 25 wt % (e.g., in particular from about 5 wt % to about 23 wt %, from about 6 wt % to about 20 wt %, from about 6.5 wt % to about 20 wt %, or from about 6.5 wt % to about 15 wt %) of the star diblock and triblock copolymer and linear diblock and triblock copolymer.

[0105] The star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure may advantageously be used in the formulation of lubricating oil compositions for passenger car and heavy-duty diesel engines, e.g., for crankcases, and in the formulation of manual and/or automatic transmission fluids. The lubricating oil compositions may advantageously comprise a concentrate of the star diblock and triblock copolymers and linear diblock and triblock copolymers, diluent oil component(s) of lubricating viscosity, the amount of VM or VII concentrate and/or the concentrated amount of linear diblock and triblock copolymers and star diblock and triblock copolymers desirably being effective to modify the viscosity index of the lubricating oil composition, being formulation flexible for wide range of SAE viscosity grades with only one product, being shear stable, and being effective in soot handling and piston cleanliness versus OCP VM, and optionally other additives as needed to provide the lubricating oil/transmission fluid composition with the required properties. Once diluted, e.g., from concentrated form for the relevant application, lubricating oil and transmission fluid compositions may contain the star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure in an effective amount to modify the viscosity index of the lubricating oil and transmission fluid compositions, e.g., an amount from about 0.1 wt % to about 2.5 wt %, or from about 0.3 wt % to about 1.5 wt %, or from about 0.4 wt % to about 1.3 wt %, stated as mass percent active ingredient (AI) in the fully formulated lubricating oil/transmission fluid composition.

[0106] In an embodiment, the concentrate may be formulated into a lubricating oil composition having a viscosity grade of SAE 25 W-X, SAE 20 W-X, SAE 15 W-X, SAE 10 W-X, SAE 5 W-X, or SAE 0 W-X, where X represents any one of 8, 12, 16, 20, 30, 40, 50, and 60.

[0107] In an embodiment, the lubricating oil composition may have a high temperature, high shear (HTHS) viscosity as measured by ASTM D4683 at 150 C. of from greater than about 1.7 mPa.Math.s, to less than about 6.5 mPa.Math.s, or greater than about 1.8 mPa.Math.s, to less than about 5.4 mPa.Math.s, or greater than about 2.0 mPa.Math.s, to less than about 4.5 mPa.Math.s.

[0108] In an embodiment, the lubricating oil composition may have improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers having a coupling efficiency of a polyalkenyl coupling agent and arms less than about 70%, or less than about 60%, or less than about 50%, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1.

[0109] In an embodiment, the lubricating oil composition may have improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having a star diblock and triblock copolymers and linear diblock and triblock copolymers wherein PA has a number average molecular weight less than about 10,000 Daltons, or less than about 9,000 Daltons, less than about 8,000 Daltons; or wherein PA is present in the star diblock and triblock copolymers and the linear diblock and triblock copolymers in an amount less than about 20 wt. %, or less than about 18 wt. %, less than about 16 wt. %, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1.

[0110] The star diblock and triblock copolymers and linear diblock and triblock copolymers of the present disclosure may comprise the sole VII or VM, or may be used in combination with other VIIs or VMs, for example, in combination with a VII or VM comprising polyisobutylene, copolymers of ethylene and propylene (OCP), polymethacrylates, methacrylate copolymers, copolymers of an unsaturated dicarboxylic acid and a vinyl compound, interpolymers of styrene and acrylic esters, and hydrogenated copolymers of styrene/isoprene, styrene/butadiene, and other hydrogenated isoprene/butadiene copolymers, as well as the partially hydrogenated homopolymers of butadiene and isoprene.

[0111] The star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure may advantageously exhibit a relatively similar thickening efficiency across an array of different types or Groups of diluent oil base stocks, such as by exhibiting a relatively low thickening efficiency (TE) span. As defined below, TE span measurements may typically involve thickening efficiency measurements of linear diblock and triblock copolymers in at least three (preferably at least four) types of reference oils, or involving at least one reference oil in at least three Groups of reference oils (e.g., at least a Group I oil, a Group II oil, a Group III oil, a Group IV oil, or mixtures thereof). In particular, four different types of reference oils can be used, across three Groupsa standard Group III oil (e.g., a natural base stock); a non-standard Group III oil (e.g., a synthetic GTL base stock); a Group II oil; and a Group IV oil. In particular, the TE span of the star diblock and triblock copolymers and linear diblock and triblock copolymers can advantageously be at most about 0.5 or at most about 0.4, optionally but preferably while the star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure further exhibit an average Group III thickening efficiency (i.e., if applicable, a simple numerical average of the thickening efficiencies in the standard and non-standard Group III base stocks) of at least 1.7 or at least 1.8. Additionally or alternatively, in particular, the viscosity index of a 1 wt % solution of linear diblock and triblock copolymers in Group II base stock (grams of linear block copolymer per 100 grams base stock) may be 165 or less, 150 or less, or 140 or less (e.g., at least 90).

[0112] Optionally but preferably, the star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure may advantageously exhibit flowability, particularly in concentrate forms. Beaker pour testing indicates the relative amount (weight) of a VM or VII concentrate that flows out of a beaker in a proscribed time period. Tan testing indicates a relative viscoelastic response of a composition/concentrate, which, for flowable samples, can indicate flowability or lack thereof. Thus, in addition to having an appropriately low KV100, star diblock and triblock copolymer and linear diblock and triblock copolymer concentrates may exhibit a 80 C. beaker pour of at least 75% (e.g., at least 81%, at least 83%, at least 85%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, or at least 95%; optionally up to 99% or up to 98%), and/or a 25 C. tan (G/G) of at least 0.7 (e.g., at least 0.8, at least 1.0, at least 1.3, at least 1.6, at least 1.7, at least 1.8, at least 1.9, at least 2.0, at least 2.2, at least 2.4, at least 2.6, at least 2.8, at least 3.0, at least 3.5, at least 4.0, at least 4.5, or at least 5.0; optionally up to 50, up to 30, or up to 20).

[0113] In addition to a 80 C. beaker pour of at least 80% and a 25 C. tan (G/G) of at least 0.7, star diblock and triblock copolymer and linear diblock and triblock copolymers may exhibit a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20%, or less than about 15%, or less than about 10%, or less than about 6%, as determined by ASTM D6278-98.

[0114] Diluent oil components of lubricating viscosity useful in the context of the lubricating oil compositions of the present disclosure may be selected from natural lubricating oils, synthetic lubricating oils, and mixtures thereof. The diluent oil component may range in viscosity from light distillate mineral oils to heavy lubricating oils such as gasoline engine oils, mineral lubricating oils, and heavy-duty diesel oils. Generally, the (kinematic) viscosity of the diluent oil component may range from about 2 cSt to about 40 cSt, in particular from about 4 cSt to about 20 cSt, as measured at 100 C., i.e., prior to addition of the star diblock and triblock copolymers and linear diblock and triblock copolymers thereto in order to form the lubricating oil composition according to the present disclosure.

[0115] Natural oil components may include animal oils, vegetable oils (e.g., castor oil, lard oil, etc.), liquid petroleum oils, and hydrorefined, solvent-treated or acid-treated mineral oils of the paraffinic, naphthenic, and mixed paraffinic-naphthenic types, and combinations thereof. Oils of lubricating viscosity derived from coal or shale may additionally or alternatively serve as useful oil components according to the present disclosure.

[0116] Synthetic oil components may include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and copolymerized olefins (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(l-hexenes), poly(l-octenes), poly(l-decenes)); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and derivatives, analogs, homologs, copolymers, and combinations thereof.

[0117] Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These are exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene and/or propylene oxide, the alkyl and/or aryl ethers of polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having a (number average) molecular weight of about 1000 or diphenyl ether of poly-ethylene glycol having a (number average) molecular weight of about 1000 to about 1500), and/or mono- and poly-carboxylic esters thereof, for example, acetic acid esters, mixed C.sub.3-C.sub.8 fatty acid esters, and C.sub.13 oxo acid diester of tetraethylene glycol.

[0118] Another suitable class of synthetic oil components comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids) with any of a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol). Specific examples of such esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid.

[0119] Additional or alternative esters that may be useful as synthetic oil components may include those made from C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol esters such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.

[0120] Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-silicone oils and silicate oils comprise another useful class of synthetic oil components; such oils may include tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl) silicate, tetra-(4-methyl-2-ethylhexyl) silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane, poly(methyl) siloxanes, poly(methyl-phenyl) siloxanes, and combinations thereof. Other additional or alternative synthetic oil components may include liquid esters of phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

[0121] VM and VII concentrates according to the present disclosure may consist essentially of (or may consist of) star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure, a diluent oil, and optionally a pour point depressant. However, when VM or VII concentrates include more than those components, they may advantageously include one or more lubricant oil composition additives, such as (but not necessarily limited to) a dispersant (e.g., an ashless dispersant), a detergent, an anti-wear agent, an antioxidant, a corrosion inhibitor, a friction modifier, an antifoamant, a seal-swelling control agent, or a combination thereof. VM and VII concentrates containing a combination of such additives may alternatively be called additive concentrates (or addpacks). The concentrates, prior to or after addition of any additives, or irrespective of any other additives, may employ from 5 mass % to 25 mass % (e.g., from 5 mass % to 18 mass % or from 10 mass % to 15 mass %) of the concentrate containing the star diblock and triblock copolymers and linear diblock and triblock copolymers and from 75 mass % to 95 mass % (e.g., from 82 mass % to 95 mass % or from 85 mass % to 90 mass %) of the diluent oil.

[0122] Lubricant oil compositions containing the star diblock and triblock copolymers and linear diblock and triblock copolymers according to the present disclosure, by themselves or as VM or VII concentrates according to the present disclosure, may also contain similar additives or addpacks.

[0123] Pour point depressants, otherwise known as lube oil flow improvers (LOFI), lower the minimum temperature at which the fluid will flow or can be poured. Such additives are well known. Typical of those additives that may improve the low temperature fluidity of the fluid are C.sub.8 to C.sub.18 dialkyl fumarate/vinyl acetate copolymers, polymethacrylates, and combinations thereof.

[0124] Ashless dispersants typically facilitate suspension of oil insolubles resulting from oxidation of a lubricating oil composition during wear or combustion. They are particularly advantageous for preventing the precipitation of sludge and the formation of varnish, particularly in gasoline engines.

[0125] Metal-containing or ash-forming detergents may function both as detergents to reduce or remove deposits and as acid neutralizers/rust inhibitors, thereby reducing wear and corrosion and extending engine life. Detergents generally comprise a polar head with a long hydrophobic tail, with the polar head comprising a metal salt of an acidic organic compound. The salts may contain a substantially stoichiometric amount of the metal in which case they are usually described as normal or neutral salts, and would typically have a total base number or TBN (as can be measured by ASTM D2896) from 0 to 80. A large amount of a metal base may be incorporated by reacting excess metal compound (e.g., an oxide or hydroxide) with an acidic gas (e.g., carbon dioxide). The resulting overbased detergent may contain neutralized detergent as the outer layer of a metal base (e.g., carbonate) micelle. Such overbased detergents may have a TBN of 150 or greater, and typically from 250 to 450 or more.

[0126] Dihydrocarbyl dithiophosphate metal salts are frequently used as antiwear and antioxidant agents in lubricating oil compositions. The metal may be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel, or copper. The zinc salts are most commonly used in lubricating oils and may be prepared in accordance with known techniques, e.g., by first forming a dihydrocarbyl dithiophosphoric acid (DDPA), usually by reaction of one or more alcohol or a phenol with P.sub.2S.sub.5 and then neutralizing the formed DDPA with a zinc compound. For example, a dithiophosphoric acid may be made by reacting mixtures of primary and secondary alcohols. Alternatively, multiple dithiophosphoric acids can be prepared where the hydrocarbyl groups on one are entirely secondary in character and the hydrocarbyl groups on the others are entirely primary in character. To make the zinc salt, any basic or neutral zinc compound could be used but the oxides, hydroxides, and carbonates are most generally employed. Commercial additives frequently contain an excess of zinc due to the use of an excess of the basic zinc compound in the neutralization reaction.

[0127] Oxidation inhibitors or antioxidants reduce the tendency of lubricating oil compositions to deteriorate in service. Oxidative deterioration can be evidenced by sludge in the lubricant, varnish-like deposits on the metal surfaces, and by viscosity growth. Such oxidation inhibitors may include, but are not necessarily limited to, hindered phenols, alkaline earth metal salts of alkylphenolthioesters such as having C.sub.5 to C.sub.12 alkyl side chains, calcium nonylphenol sulfide, oil soluble phenates and sulfurized phenates, phosphosulfurized or sulfurized hydrocarbons, phosphorous esters, metal thiocarbamates, oil soluble copper compounds as described in U.S. Pat. No. 4,867,890, molybdenum-containing compounds, aromatic amines, and the like, and combinations and/or reaction products thereof.

[0128] Known friction modifiers include oil-soluble organo-molybdenum compounds. Such organo-molybdenum friction modifiers may also provide antioxidant and antiwear credits to a lubricating oil composition. As an example of such oil soluble organo-molybdenum compounds, there may be mentioned the dithiocarbamates, dithiophosphates, dithiophosphinates, xanthates, thioxanthates, sulfides, and the like, and mixtures thereof. Particularly exemplary are molybdenum dithiocarbamates, dialkyldithiophosphates, alkyl xanthates, alkylthioxanthates, and combinations thereof.

[0129] Other known friction modifying materials, which may additionally or alternatively be present in the lubricating oil compositions according to the present disclosure, may include glyceryl monoesters of higher fatty acids, for example, glyceryl mono-oleate; esters of long chain polycarboxylic acids with diols, for example, the butane diol ester of a dimerized unsaturated fatty acid; oxazoline compounds; alkoxylated alkyl-substituted mono-amines, diamines and alkyl ether amines, for example, ethoxylated tallow amine and ethoxylated tallow ether amine; and combinations thereof.

[0130] Foam control in lubricating oil compositions can be provided by an antifoamant of the polysiloxane type, for example, silicone oil and/or polydimethyl siloxane.

[0131] Some of the above-mentioned additives can provide a multiplicity of effects; thus, for example, a single additive may act as a dispersant-oxidation inhibitor. This approach is well known and need not be further elaborated herein.

[0132] It may also be necessary to include an additive which maintains the stability of the viscosity of the blend/composition. Thus, although polar group-containing additives may achieve a suitably low viscosity in the pre-blending stage, it has been observed that some compositions may age, or increase in viscosity when stored for prolonged periods. Additives that are typically effective in controlling this viscosity increase/ageing phenomenon may include long chain hydrocarbons functionalized by reaction with mono-/di-carboxylic acids and/or anhydrides used in the preparation of the ashless dispersants, as hereinbefore disclosed.

[0133] Representative effective amounts of such additional additives, when used in (crankcase) lubricating oil compositions according to the present disclosure, are listed below:

TABLE-US-00001 Mass % Mass % ADDITIVE (broad) (in particular) Ashless Dispersant 0.1-20 1-8 Metal Detergents 0.1-15 0.2-9 Corrosion Inhibitor 0-5 0-1.5 Metal Dihydrocarbyl Dithiophosphate 0.1-6 0.1-4 Antioxidant 0-5 0.01-2 Pour Point Depressant 0.01-5 0.01-1.5 Antifoaming Agent 0-5 0.001-0.15 Supplemental Antiwear Agents 0-1.0 0-0.5 Friction Modifier 0-5 0-1.5 Base stock (copolymer + diluent oil) Balance Balance

[0134] Additionally or alternatively, the present disclosure may include one or more of the following embodiments.

[0135] Embodiment 1. A viscosity index improver (VII) or viscosity modifier (VM) concentrate comprising: from about 60 parts to about 95 parts of a diluent oil; and from about 5 parts to about 40 parts of star diblock and triblock copolymers characterized by the formula:

##STR00011## [0136] and linear diblock and triblock copolymers characterized by the formula:

##STR00012## [0137] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene (e.g., styrene or styrenic monomer); D represents a block derived from at least one diene; n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; [0138] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0139] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0140] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0141] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0142] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; [0143] wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; [0144] wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers are present in an amount effective to modify a lubricating kinematic viscosity at approximately 100 C. (KV100) of the concentrate; [0145] wherein the concentrate comprises at least 50 wt % of the diluent oil and the effective amount of the star diblock and triblock copolymers and linear diblock and triblock copolymers is such that the concentrate comprises at least about 6 wt. % (e.g., from about 6.0 wt. % to about 14.0 wt. %) of the star diblock and triblock copolymers and linear diblock and triblock copolymers; [0146] wherein a KV100 of the diluent oil is from about 2 cSt to about 40 cSt, and a KV100 of the concentrate is about 3000 cSt or less, and [0147] wherein the concentrate has a .sup.80 C. beaker pour of at least about 75% or a 25 C. tan of at least about 0.7, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.6, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20% as determined by ASTM D6278-98.

[0148] Embodiment 2. A concentrate according to embodiment 1, wherein the concentrate comprises from about 7.0 wt % to about 14 wt %, or from about 8.0 wt % to about 13 wt %, or from about 9.0 wt % to about 12 wt %, of the star diblock and triblock copolymers and the linear diblock and triblock copolymers.

[0149] Embodiment 3. A concentrate according to any one of the previous embodiments, wherein the KV100 of the concentrate is about 2500 cSt or less, or about 2000 cSt or less, or about 1500 cSt or less, or about 1000 cSt or less.

[0150] Embodiment 4. A concentrate according to any one of the previous embodiments, wherein D has a number average molecular weight from about 22,500 Daltons to about 52,500 Daltons, PA has a number average molecular weight from about 12,500 Daltons to about 32,500 Daltons, and D has a number average molecular weight from about 12,500 Daltons or less.

[0151] Embodiment 5. A concentrate according to any one of the previous embodiments, wherein D has a number average molecular weight from about 25,000 Daltons to about 45,000 Daltons, PA has a number average molecular weight from about 15,000 Daltons to about 30,000 Daltons, and D has a number average molecular weight from about 12,000 Daltons or less.

[0152] Embodiment 6. A concentrate according to any one of the previous embodiments, wherein D has a number average molecular weight from about 31,500 Daltons to about 41,500 Daltons, PA has a number average molecular weight from about 14,000 Daltons to about 18,000 Daltons, and D has a number average molecular weight from about 10,000 Daltons or less.

[0153] Embodiment 7. A concentrate according to any one of the previous embodiments, wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 3.0:1 or greater, or about 3.5:1 or greater, or about 4.0:1 or greater.

[0154] Embodiment 8. A concentrate according to any one of the previous embodiments, wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is greater than about 1.40:1, or greater than about 1.70:1, or greater than about 1.90:1.

[0155] Embodiment 9. A concentrate according to any one of the previous embodiments, wherein n has a value from about 5 to about 20.

[0156] Embodiment 10. A concentrate according to any one of the previous embodiments, wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers have a total number average molecular weight of from about 100,000 Daltons to about 1,000,000 Daltons, or from about 200,000 Daltons to about 1,000,000 Daltons, or from about 400,000 Daltons to about 800,000 Daltons.

[0157] Embodiment 11. A concentrate according to any one of the previous embodiments, wherein PA is present in the star diblock and triblock copolymers and linear diblock and triblock copolymers in an amount from about 20 wt. % to about 35 wt. %, or from about 25 wt. % to about 33 wt. %, or from about 30 wt. % to about 40 wt. %, based on the total weight of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

[0158] Embodiment 12. A concentrate according to any one of the previous embodiments, wherein the KV100 of the concentrate is from about 100 cSt to about 3000 cSt, or from about 100 cSt to about 2500 cSt, or from about 100 cSt to about 2000 cSt.

[0159] Embodiment 13. A concentrate according to any one of the previous embodiments, wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 65%, or greater than about 80%, or greater than about 90%.

[0160] Embodiment 14. A concentrate according to any one of the previous embodiments, wherein the D and D dienes each individually comprise butadiene, isoprene, or mixtures of butadiene and isoprene in any weight ratio, but are not identical to each other in molecular weight, in chemical composition, or both, and wherein the D and D blocks are substantially hydrogenated after polymerization.

[0161] Embodiment 15. A concentrate according to any one of the previous embodiments, wherein at least one of diene blocks D and D, or each of diene blocks D and D, are random isoprene/butadiene copolymer blocks having isoprene and butadiene in any weight ratio, or isoprene polymer blocks, or butadiene polymer blocks.

[0162] Embodiment 16. A concentrate according to any one of the previous embodiments, wherein diene block D is a random isoprene/butadiene copolymer block having isoprene and butadiene in any weight ratio, or isoprene polymer block, or butadiene polymer block, and diene block D is a butadiene polymer block.

[0163] Embodiment 17. A concentrate according to any one of the previous embodiments, wherein diene blocks D and D are hydrogenated to remove at least about 80%, or at least 90%, or at least 95%, of unsaturations, or are fully hydrogenated.

[0164] Embodiment 18. A concentrate according to any one of the previous embodiments, wherein the polyalkenyl coupling agent is selected from the group consisting of benzene, toluene, xylene, anthracene, naphthalene and durene, which are substituted with at least two alkenyl groups, attached directly thereto.

[0165] Embodiment 19. A concentrate according to any one of the previous embodiments, wherein the polyalkenyl coupling agent is selected from the group consisting of divinyl benzene, trivinyl benzene, tetravinyl benzene, divinyl xylene, trivinyl xylene, tetravinyl ortho-xylene, tetravinyl meta-xylene, tetravinyl para-xylene, divinyl naphthalene, divinyl ethyl benzene, divinyl biphenyl, diisobutenyl benzene, diisopropenyl benzene, and diisopropenyl biphenyl.

[0166] Embodiment 20. A concentrate according to any one of the previous embodiments, which is formulated into a lubricating oil composition having a viscosity grade of SAE 25 W-X, SAE 20 W-X, SAE 15 W-X, SAE 10 W-X, SAE 5 W-X, or SAE 0 W-X, where X represents any one of 8, 12, 16, 20, 30, 40, 50, and 60.

[0167] Embodiment 21. A concentrate according to any one of the previous embodiments, wherein the concentrate has a .sup.80 C. beaker pour of at least about 85% or a 25 C. tan of at least about 1.5, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.7, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 15% as determined by ASTM D6278-98.

[0168] Embodiment 22. A concentrate according to any one of the previous embodiments, wherein the concentrate has a .sup.80 C. beaker pour of at least about 90% or a 25 C. tan of at least about 2.0, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.8, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 10% as determined by ASTM D6278-98.

[0169] Embodiment 23. A concentrate according to any one of the previous embodiments, wherein the diluent oil comprises a Group I, Group II, Group III, Group IV base stock, or any thereof.

[0170] Embodiment 24. A concentrate according to any one of the previous embodiments, further comprising one or more of an ashless dispersant, a detergent, an anti-wear agent, an antioxidant, a corrosion inhibitor, a friction modifier, an antifoamant, a seal-swelling control agent, or a combination thereof.

[0171] Embodiment 25. A method of modifying the kinematic viscosity at approximately 100 C. (KV100) of the viscosity index improver (VII) or viscosity modifier (VM) concentrate according to any one of the previous embodiments, the method comprising adding to the concentrate an effective amount of the star diblock and triblock copolymers characterized by the formula:

##STR00013## [0172] and the linear diblock and triblock copolymers characterized by the formula:

##STR00014## [0173] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene (e.g., styrene or styrenic monomer); D represents a block derived from at least one diene; n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; [0174] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0175] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0176] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0177] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0178] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; [0179] wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; [0180] wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers are present in an amount effective to modify a lubricating kinematic viscosity at approximately 100 C. (KV100) of the concentrate; [0181] wherein the concentrate comprises at least 50 wt % of the diluent oil and the effective amount of the star diblock and triblock copolymers and linear diblock and triblock copolymers is such that the concentrate comprises at least about 6 wt. % (e.g., from about 6.0 wt. % to about 14.0 wt. %) of the star diblock and triblock copolymers and linear diblock and triblock copolymers; [0182] wherein a KV100 of the diluent oil is from about 2 cSt to about 40 cSt, and a KV100 of the concentrate is about 3000 cSt or less, and [0183] wherein the concentrate has a .sup.80 C. beaker pour of at least about 75% or a 25 C. tan of at least about 0.7, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.6, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20% as determined by ASTM D6278-98.

[0184] Embodiment 26. A lubricating oil composition comprising a major amount of oil of lubricating viscosity, and the viscosity index improver (VII) or viscosity modifier (VM) concentrate according to any one of the previous embodiments, in an amount effective to modify the viscosity index of the lubricating oil composition.

[0185] Embodiment 27. A lubricating il composition according to any one of the previous embodiments, further comprising one or more of an ashless dispersant, a detergent, an anti-wear agent, an antioxidant, a corrosion inhibitor, a friction modifier, an antifoamant, a seal-swelling control agent, or a combination thereof.

[0186] Embodiment 28. A lubricating oil composition according to any one of the previous embodiments, having a high temperature, high shear (HTHS) viscosity as measured by ASTM D4683 at 150 C. of from greater than about 1.7 mPa.Math.s, to less than about 6.5 mPa.Math.s.

[0187] Embodiment 29. A lubricating oil composition according to any one of the previous embodiments, having improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers having a coupling efficiency of a polyalkenyl coupling agent and arms less than about 70%, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1.

[0188] Embodiment 30. A lubricating oil composition according to any one of the previous embodiments, having improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers and linear diblock and triblock copolymers wherein PA has a number average molecular weight less than about 10,000 Daltons, or wherein PA is present in the star diblock and triblock copolymers and linear diblock and triblock copolymers in an amount less than about 20 wt. %, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1.

[0189] Embodiment 31. A lubricating oil composition according to any one of the previous embodiments, having a viscosity grade of SAE 25 W-X, SAE 20 W-X, SAE 15 W-X, SAE 10 W-X, SAE 5 W-X, or SAE 0 W-X, where X represents any one of 8, 12, 16, 20, 30, 40, 50, and 60.

[0190] Embodiment 32. A lubricating oil composition according to any one of the previous embodiments, for passenger car, heavy-duty diesel, marine diesel engines, functional fluids, and manual/automatic transmission fluids.

[0191] Embodiment 33. A polymer suitable for use as a viscosity index improver (VII) or viscosity modifier (VM) for a lubricating oil composition comprising star diblock and triblock copolymers characterized by the formula:

##STR00015## [0192] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene (e.g., styrene or styrenic monomer); D represents a block derived from at least one diene but which is typically not identical to D (in molecular weight, in chemical composition, or both); n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25, or from about 5 to about 20; [0193] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0194] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0195] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0196] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0197] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; and [0198] wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%.

[0199] Embodiment 34. A polymer suitable for use as a viscosity index improver (VII) or viscosity modifier (VM) for a lubricating oil composition comprising linear diblock and triblock copolymers characterized by the formula:

##STR00016## [0200] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene (e.g., styrene or styrenic monomer); D represents a block derived from at least one diene but which is typically not identical to D (in molecular weight, in chemical composition, or both); [0201] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0202] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0203] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0204] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; and [0205] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater.

EXAMPLES

[0206] This disclosure may be further understood by reference to the following (non-limiting) examples. In the following Examples, the properties of certain components or the composition itself are described using certain terms of art, as defined below. In the Examples, all parts are parts by weight, unless otherwise noted.

[0207] Shear Stability Index (SSI) measures the ability of polymer components in crankcase lubricants to maintain thickening power during shear conditions and is typically indicative of the resistance of a polymer to degradation under service conditions. The higher the SSI, the less stable the polymer, i.e., the more susceptible it is to degradation. SSI is defined as the percentage of polymer-derived viscosity loss and is calculated as follows:

[00001]$\mathrm{SSI}=100\frac{{\mathrm{kv}}_{\mathrm{fresh}}-{\mathrm{kv}}_{\mathrm{after}}}{{\mathrm{kv}}_{\mathrm{fresh}}-{\mathrm{kv}}_{\mathrm{oil}}}$ [0208] wherein kv.sub.fresh is the kinematic viscosity of the polymer-containing solution before degradation, and kv.sub.after is the kinematic viscosity of the polymer-containing solution after degradation. SSI is conventionally determined using ASTM D6278-98 (known as the Kurt-Orban (KO) or DIN bench test). The polymer under test may be dissolved in suitable base oil (for example, solvent extracted 150 neutral) to a relative viscosity of about 4-5 cSt at 100 C., and the resulting fluid may be pumped through the testing apparatus specified in the ASTM D6278-98 protocol.

[0209] Thickening Efficiency (TE) is representative of a polymer's ability to thicken oil per unit mass and is defined as:

[00002]$\mathrm{TE}=\frac{2}{c\ln 2}\ln \left(\frac{{\mathrm{kv}}_{\mathrm{oil}+\mathrm{polymer}}}{{\mathrm{kv}}_{\mathrm{oil}}}\right)$ [0210] wherein c is polymer concentration (grams of polymer/100 grams solution), kV.sub.oil+polymer is kinematic viscosity of the polymer in the reference oil, and kv.sub.oil is kinematic viscosity of the reference oil. In most cases, as in the Examples hereinbelow, TE is measured at approximately 1 wt %, or 1.5 wt %, concentration in a reference oil.

[0211] Thickening efficiency span (TE span) is representative of the relative uniformity of a polymer's thickening efficiency (TE) across an array of different types or Groups of reference oils, i.e., involving at least three (preferably at least four) types of reference oils, or involving at least one reference oil in at least three Groups of reference oils (e.g., at least a Group II oil, a Group III oil, and a Group IV oil). In particular, four different types of reference oils can be used, across three Groupsa standard Group III oil (e.g., a natural base stock); a non-standard Group III oil (e.g., a synthetic GTL base stock); a Group II oil; and a Group IV oil. In the present disclosure, TE span is evaluated at approximately the same concentration in each different reference oil, e.g., 1 wt % polymer concentration. The TE span is represented by the absolute value of the largest binary thickening efficiency difference (TE) between a polymer in any two different reference oils in the array.

[0212] Cold Cranking Simulator (CCS) is a measure of the cold-cranking characteristics of crankcase lubricants and is conventionally determined using a technique described in ASTM D5293-92.

[0213] Scanning Brookfield is used to measure the apparent viscosity of engine oils at low temperatures. A shear rate of approximately 0.2 s.sup.1 is produced at shear stresses below 100 Pa. Apparent viscosity is measured continuously as the sample is cooled at a rate of about 1 C./hr over the range of about 5 C. to about 40 C., or to the temperature at which the viscosity exceeds 40,000 mPa.Math.s (cPs). The test procedure is defined in ASTM D5133-01. The measurements resulting from the test method are reported as viscosity in mPa.Math.s or the equivalent cPs, the maximum rate of viscosity increase (Gelation Index) and the temperature at which the Gelation Index occurs.

[0214] Mini Rotary Viscometer (MRV)-TP-1 measures yield stress and viscosity of engine oils after cooling at controlled rates over a period of 45 hours to a final test temperature between about 15 C. and about 40 C. The temperature cycle is defined in SAE Paper No. 850443, by K. O. Henderson et al. Yield stress (YS) is measured first at the test temperature and apparent viscosity is then measured at a shear stress of 525 Pa over a shear rate of about 0.4 s.sup.1 to about 15 s.sup.1. Apparent viscosity is reported in mPa.Math.s, or the equivalent cPs.

[0215] Pour point measures the ability of an oil composition or component to flow as the temperature is lowered. Performance is reported in C. and is measured using the test procedure described in ASTM D97-02. After preliminary heating, the sample is cooled at a specified rate and examined at intervals of 3 C. for flow characteristics. The lowest temperature at which movement of the specimen is observed is reported as the pour point. Each of MRV-TP-1, CCS, and pour point is typically indicative of the low temperature viscometric properties of oil compositions.

[0216] A Beaker Pour test measures the bulk flow of a concentrate at a given temperature out of a 600-mL beaker oriented at an angle of 96, relative to a horizontal table surface. Beaker Pour testing can be done for samples held at a given temperature for only 24 hours (week 0), or for extended periods of time, such as up to 12 weeks or longer. Beaker Pour values are a fraction, expressed as a percentage, of sample that flows out of the beaker in 2 minutes (=[sample plus beaker weight prior to test]-[sample plus beaker weight immediately after test]). Herein, Beaker Pour tests are reported for week 0 samples held at 80 C. (1 C.), with any portion of a sample present on the exterior walls of the beaker in its upright position after the test (sitting flat on the horizontal table surface) being wiped off with a dry tissue, for safety.

[0217] Another measure of flowability of a composition involves tan , which is a ratio of the loss modulus (G) of a composition to the storage modulus (G). Although tan can theoretically encapsulate a ratio of tensile moduli (E/E), herein it is understood as a ratio of shear moduli (G/G), which is more indicative of the flowable, viscous state in which the diblock and triblock copolymeric samples exist. Tan & values expressed herein were measured with an ARES G2 rheometer using 25 mm parallel plates with a gap of either 0.5 mm or 1 mm, including its native software package (TRIOS), commercially available from TA Instruments of New Castle, DE. Samples were cycled twice from 25 C. to 200 C. and back at a 5.0 C./min ramp rate, and tan data reflected measurements taken at a temperature of 25 C. at the beginning of the first ramp up (values at the beginning of the second ramp up were checked to be within measurement error) at an angular frequency of 10 rad/s and a maximum oscillation strain of 10%.

[0218] Viscosity Index can measure the susceptibility of a lubricant composition (or base stock) to changes in temperature. Viscosity index can be calculated using the following formula:

[00003]$\mathrm{VI}=100\frac{\text{?}}{\text{?}}$$\text{?}\text{indicates text missing or illegible when filed}$ [0219] where U is the composition's kinematic viscosity at 40 C. (104 F.; KV40), and L and H are values based on the composition's kinematic viscosity at 100 C. (212 F.; KV100). L and H are the KV40 values for oils of VI 0 and 100 respectively, having the same KV100 as the oil whose VI is to be determined. L and H values can be found, for example, in ASTM D2270.

[0220] As used herein and in FIGS. 1-15, a conventional VM is a diblock or triblock copolymer having at least one of: D having a number average molecular weight of greater than 10,000 Daltons, a ratio of the number average molecular weight of D to the number average molecular weight of D of less than 4.0:1, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of less than 1.5:1.

EXAMPLES

[0221] Concentrates were prepared having star triblock copolymers of the type (D-PA-D) n-X, according to the present disclosure. In these concentrates, the higher molecular weight diene block is D, and the lower molecular weight diene block is D. The polyarene block in these concentrates is a polystyrene block. The star triblock copolymers are included in concentrate form with active ingredient (AI) concentrations of about 5 mass %, about 6 mass %, about 7 mass %, about 8 mass %, about 9 mass %, about 10 mass %, and about 11 mass %, as substantially dissolved or suspended in a diluent oil having a KV100 of about 4 cSt (Yubase 4, PAO4, GTL4, or Star4). The KV100 of each concentrate sample, as well as the molecular weights of the block copolymer segments of the star triblock copolymers, the polymer composition, the base stock diluent, the active ingredient concentration, and gel formation, is delineated in FIG. 1. Where a star triblock copolymers exhibited gelation during the process of dissolving or suspending it in its diluent oil, the KV100 in FIG. 1 indicates Gel. As can be seen in FIG. 1, at active ingredient concentrations even as high as about 11 mass %, identified star triblock copolymers did not gel and had a measurable KV100.

[0222] Additional concentrates were prepared having star triblock copolymers of the type (D-PA-D)n-X, according to the present disclosure. In these concentrates, the higher molecular weight diene block is D, and the lower molecular weight diene block is D. The polyarene block in these concentrates is a polystyrene block. The star triblock copolymers are included in concentrate form with active ingredient (AI) concentrations of about 5 mass %, about 10 mass %, and about 11 mass %, as substantially dissolved or suspended in a diluent oil having a KV100 of about 4 cSt (Yubase 4). The flowability of each concentrate sample, as well as the molecular weights of the block copolymer segments of the star triblock copolymers, the polymer composition, the base stock diluent, the active ingredient concentration, beaker pour testing (concentrate poured out at 40 C., 60 C. and 80 C.), and a tan value (measured at 25 C.), is delineated in FIG. 2. Where star triblock copolymers exhibited gelation, FIG. 2 indicates Gel. As can be seen in FIG. 2, at active ingredient concentrations even as high as about 10 mass % and about 11 mass %, identified star triblock copolymers did not gel and exhibited desirable flow properties.

[0223] Additional concentrates were prepared having star triblock copolymers of the type (D-PA-D)n-X, according to the present disclosure. In these concentrates, the higher molecular weight diene block is D, and the lower molecular weight diene block is D. The polyarene block in these concentrates is a polystyrene block. The star triblock copolymers are included in concentrate form, as substantially dissolved or suspended in a diluent oil having a KV100 of about 4 cSt (Group III). The copolymer thickening efficiency (TE) in Group III testing oils at 1% and 1.5% polymer treat rate, as well as the molecular weights of the block copolymer segments of the star triblock copolymers, the polymer composition, the active ingredient concentration, the coupling percent, is delineated in FIG. 3. As can be seen in FIG. 3, identified star triblock copolymers exhibited desirable thickening efficiency.

[0224] Generally, though not for all applications, lower KV100 values at relatively higher AI concentrations is seen as desirable. Additionally or alternatively, the ability of a star triblock copolymer concentrate sample to have a KV100 of about 3000 cSt or less or about 2000 cSt or less, at as high an AI concentration as possible, is seen as desirable. Further additionally or alternatively, a star triblock copolymer concentrate exhibiting a Beaker Pour (week 0) value of at least 87% (or of at least 90%, and optionally also up to 99%), can be seen as desirable. Still further additionally or alternatively, a linear triblock copolymer concentrate exhibiting a tan value (measured at 25 C.) of at least 1.8 (and optionally also of up to 30) can be seen as desirable.

[0225] Generally, though not for all applications, intermediate or higher individual thickening efficiencies, and high or very high viscosity indices can be seen as desirable. In particular, star triblock copolymers having an average thickening efficiency in Group III diluent oil of at least 1.7 or at least 1.8 can be seen as desirable.

[0226] FIGS. 4, 5, and 6 show treat rate advantage of lubricating oil composition treated with triblock copolymers of this disclosure (i.e., D having a number average molecular weight of 10,000 Daltons or less, a ratio of the number average molecular weight of D to the number average molecular weight of D of 4.0:1 or greater, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of greater than 1.5:1) compared to a lubricating oil composition treated with a conventional triblock copolymer (i.e., D having a number average molecular weight of greater than 10,000 Daltons, a ratio of the number average molecular weight of D to the number average molecular weight of D of less than 4.0:1, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of less than 1.5:1). FIG. 4 shows a modeling prediction of viscometrics for 5 W-30 and 5 W-40 with a passenger car motor oil (PVMO) additive package in Group III oils. FIG. 5 shows viscometrics for 0 W-30 3.5 cP with a passenger car motor oil (PVMO) additive package in Yubase4+ and PAO. FIG. 6 shows viscometrics for 0 W-40 3.5 cP with a passenger car motor oil (PVMO) additive package in Yubase, Yubase4+, and PAO.

[0227] FIGS. 7, 8, 9, and 10 show shear stability index testing (known as the Kurt-Orban (KO) or DIN bench 15 test) results of lubricating oil composition treated with a triblock copolymer of this disclosure (i.e., D having a number average molecular weight of 10,000 Daltons or less, a ratio of the number average molecular weight of D to the number average molecular weight of D of 4.0:1 or greater, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of greater than 1.5:1) compared to a lubricating oil composition treated with a conventional triblock copolymer (i.e., D having a number average molecular weight of greater than 10,000 Daltons, a ratio of the number average molecular weight of D to the number average molecular weight of D of less than 4.0:1, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of less than 1.5:1). FIG. 7 shows KO testing results of triblock linear and star copolymers in a 4 cSt oil blended with Group III base stocks. FIG. 8 graphically depicts viscosity loss of polymer solutions in 30, 90, and 120 cycle KO shearing. FIG. 9 shows KO testing results of 1.7% triblock star copolymers in a 4 cSt oil blended with Group I base stocks. FIG. 10 graphically depicts viscosity loss of polymer solutions in 30, 90, and 120 cycle KO shearing.

[0228] FIG. 11 shows viscometric modeling prediction and testing data of linear and star triblock copolymers in a SAE API CK4 5 W-30 heavy duty diesel (HDD) formulation with HDD additive package in Yubase4 and Yubase6. The lubricating oil compositions treated with a triblock copolymer of this disclosure (i.e., D having a number average molecular weight of 10,000 Daltons or less, a ratio of the number average molecular weight of D to the number average molecular weight of D of 4.0:1 or greater, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of greater than 1.5:1) exhibit formulation flexibility compared to a lubricating oil composition treated with a conventional triblock copolymer (i.e., D having a number average molecular weight of greater than 10,000 Daltons, a ratio of the number average molecular weight of D to the number average molecular weight of D of less than 4.0:1, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of less than 1.5:1). The triblock copolymers of this disclosure can formulate wide viscosity grades including xW-20, xW-30, xW-40, etc. for both PCMO and HDD engine lubricant products.

[0229] FIGS. 12, 13, 14, and 15 show Haake rheology testing results of lubricating oil compositions treated with a triblock copolymer of this disclosure (i.e., D having a number average molecular weight of 10,000 Daltons or less, a ratio of the number average molecular weight of D to the number average molecular weight of D of 4.0:1 or greater, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of greater than 1.5:1) compared to a lubricating oil composition treated with a conventional triblock copolymer (i.e., D having a number average molecular weight of greater than 10,000 Daltons, a ratio of the number average molecular weight of D to the number average molecular weight of D of less than 4.0:1, and a ratio of the number average molecular weight of PA to the number average molecular weight of D of less than 1.5:1). FIG. 12 shows formulations and properties of lubricating oil compositions of this disclosure having star triblock copolymers at different coupling efficiencies and linear triblock copolymers (with no coupling). FIG. 13 graphically depicts Haake testing for star triblock copolymer and star arm with different coupling efficiency with 5 W-30 having 9% carbon black. FIG. 13 shows that high coupling efficiency triblock star copolymer disperses carbon black better and therefore show lower viscosity than low coupling efficiency triblock star copolymer. The small triblock arm, although containing similar polystyrene content, cannot disperse carbon black efficiently. FIG. 14 graphically depicts Haake testing for high coupling efficiency star triblock copolymers in oils with 9% carbon black, in particular, 5 W-30 oils having 9% carbon black. FIG. 14 shows that all the tested high coupling efficiency star triblock copolymers can disperse 9% carbon black effectively in the oils. FIG. 15 graphically depicts Haake testing for high coupling efficiency star triblock copolymers in oils with 12% carbon black, in particular, 5 W-30 oils having 12% carbon black. FIG. 15 shows that all the tested high coupling efficiency star triblock copolymers can disperse 12% carbon black effectively in the oils, and that high polystyrene size or content contributes to disperse 12% carbon black more effectively than lower polystyrene size or content.

PCT and EP Clauses

[0230] 1. A viscosity index improver (VII) or viscosity modifier (VM) concentrate comprising: from about 60 parts to about 95 parts of a diluent oil; and from about 5 parts to about 40 parts of star diblock and triblock copolymers characterized by the formula:

##STR00017## [0231] and linear diblock and triblock copolymers characterized by the formula:

##STR00018## [0232] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; [0233] n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; [0234] and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; [0235] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0236] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0237] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0238] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0239] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; [0240] wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; [0241] wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers are present in an amount effective to modify a lubricating kinematic viscosity at approximately 100 C. (KV100) of the concentrate; [0242] wherein the concentrate comprises at least 50 wt % of the diluent oil and the effective amount of the star diblock and triblock copolymers and linear diblock and triblock copolymers is such that the concentrate comprises from about 6.0 wt. % to about 14.0 wt. % of the star diblock and triblock copolymers and linear diblock and triblock copolymers; [0243] wherein a KV100 of the diluent oil is from about 2 cSt to about 40 cSt, and a KV100 of the concentrate is about 3000 cSt or less, and [0244] wherein the concentrate has a .sup.80 C. beaker pour of at least about 75% or a 25 C. tan of at least about 0.7, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.6, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20% as determined by ASTM D6278-98.

[0245] 2. A concentrate according to clause 1, wherein the concentrate comprises from about 7.0 wt % to about 14 wt %, or from about 8.0 wt % to about 13 wt %, or from about 9.0 wt % to about 12 wt %, of the star diblock and triblock copolymers and linear diblock and triblock copolymers.

[0246] 3. A concentrate according to clauses 1 and 2, wherein the KV100 of the concentrate is about 2500 cSt or less, or about 2000 cSt or less, or about 1500 cSt or less, or about 1000 cSt or less.

[0247] 4. A concentrate according to clauses 1-3, wherein D has a number average molecular weight from about 22,500 Daltons to about 52,500 Daltons, or from about 25,000 Daltons to about 40,000 Daltons, or from about 25,000 Daltons to about 35,000 Daltons, or from about 31,500 Daltons to about 37,500 Daltons; PA has a number average molecular weight from about 12,500 Daltons to about 32,500 Daltons, or from about 15,000 Daltons to about 30,000 Daltons, or from about 14,000 Daltons to about 18,000 Daltons; and D has a number average molecular weight of about 12,500 Daltons or less, or about 12,000 Daltons or less, or about 10,000 Daltons or less.

[0248] 5. A concentrate according to clauses 1-4, wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 3.0:1 or greater, or about 4.0:1 or greater; and wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is greater than about 1.40:1, or greater than about 1.70:1, or greater than about 1.90:1.

[0249] 6. A concentrate according to clauses 1-5, wherein the star diblock and triblock copolymers have a total number average molecular weight of from about 100,000 Daltons to about 1,000,000 Daltons, or from about 200,000 Daltons to about 1,000,000 Daltons, or from about 400,000 Daltons to about 800,000 Daltons, or from about 500,000 Daltons to about 700,000 Daltons; and wherein the linear diblock and triblock copolymers have a total number average molecular weight of from about 25,000 Daltons to about 100,000 Daltons, or from about 40,000 Daltons to about 80,000 Daltons, or from about 50,000 Daltons to about 70,000 Daltons.

[0250] 7. A concentrate according to clauses 1-6, wherein the D and D dienes each individually comprise butadiene, isoprene, or mixtures of butadiene and isoprene in any weight ratio, but are not identical to each other in molecular weight, in chemical composition, or both; or wherein at least one of diene blocks D and D, or each of diene blocks D and D, are random isoprene/butadiene copolymer blocks having isoprene and butadiene in any weight ratio, or isoprene polymer blocks, or butadiene polymer blocks; or wherein diene block D is a random isoprene/butadiene copolymer block having isoprene and butadiene in any weight ratio, or isoprene polymer block, or butadiene polymer block, and diene block D is a butadiene polymer block.

[0251] 8. A concentrate according to clauses 1-7, wherein diene blocks D and D are hydrogenated to remove at least about 80%, or at least 90%, or at least 95%, of unsaturations, or are fully hydrogenated.

[0252] 9. A concentrate according to clauses 1-8, wherein the polyalkenyl coupling agent is selected from the group consisting of benzene, toluene, xylene, anthracene, naphthalene, and durene, which are substituted with at least two alkenyl groups, attached directly thereto; divinyl benzene, trivinyl benzene, tetravinyl benzene, divinyl xylene, trivinyl xylene, tetravinyl ortho-xylene, tetravinyl meta-xylene, tetravinyl para-xylene, divinyl naphthalene, divinyl ethyl benzene, divinyl biphenyl, diisobutenyl benzene, diisopropenyl benzene, and diisopropenyl biphenyl.

[0253] 10. A concentrate according to clauses 1-9, wherein the concentrate has a .sup.80 C. beaker pour of at least about 85%, or at least about 90%; a 25 C. tan of at least about 1.0, or at least about 2.0; a thickening efficiency (TE) in a Group III diluent oil of at least about 1.7, or at least about 1.8; and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 8.0%, or less than about 6.0%, as determined by ASTM D6278-98.

[0254] 11. A concentrate according to clauses 1-10, further comprising one or more of an ashless dispersant, a detergent, an anti-wear agent, an antioxidant, a corrosion inhibitor, a friction modifier, an antifoamant, a seal-swelling control agent, or a combination thereof.

[0255] 12. A method of modifying the kinematic viscosity at approximately 100 C. (KV100) of the viscosity index improver (VII) or viscosity modifier (VM) concentrate of clauses 1-11, the method comprising adding to the concentrate an effective amount of the star diblock and triblock copolymers characterized by the formula:

##STR00019## [0256] and the linear diblock and triblock copolymers characterized by the formula:

##STR00020## [0257] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; [0258] n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; [0259] and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; [0260] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0261] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0262] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0263] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0264] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; [0265] wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%; [0266] wherein the star diblock and triblock copolymers and linear diblock and triblock copolymers are present in an amount effective to modify a lubricating kinematic viscosity at approximately 100 C. (KV100) of the concentrate; [0267] wherein the concentrate comprises at least 50 wt % of the diluent oil and the effective amount of the star diblock and triblock copolymers and linear diblock and triblock copolymers is such that the concentrate comprises from about 6.0 wt. % to about 14.0 30 wt. % of the star diblock and triblock copolymers and linear diblock and triblock copolymers; [0268] wherein a KV100 of the diluent oil is from about 2 cSt to about 40 cSt, and a KV100 of the concentrate is about 3000 cSt or less, and [0269] wherein the concentrate has a .sup.80 C. beaker pour of at least about 75% or a 25 C. tan of at least about 0.7, a thickening efficiency (TE) in a Group III diluent oil of at least about 1.6, and a shear stability index (SSI) or polymer-derived viscosity loss at approximately 100 C. (KV100) of less than about 20% as determined by ASTM D6278-98.

[0270] 13. A lubricating oil composition comprising a major amount of oil of lubricating viscosity, and the viscosity index improver (VII) or viscosity modifier (VM) concentrate of clauses 1-11, in an amount effective to modify the viscosity index of the lubricating oil composition.

[0271] 14. A lubricating oil composition according to clause 13, having a high temperature, high shear (HTHS) viscosity as measured by ASTM D4683 at 150 C. of from greater than about 1.7 mPa.Math.s, to less than about 6.5 mPa.Math.s; or having improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers having a coupling efficiency of a polyalkenyl coupling agent and arms less than about 70%, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1; or having improved soot dispersancy as compared to soot dispersancy in a lubricating oil composition having star diblock and triblock copolymers and linear diblock and triblock copolymers wherein PA has a number average molecular weight less than about 10,000 Daltons, or wherein PA is present in the star diblock and triblock copolymers and linear diblock and triblock copolymers in an amount less than about 20 wt. %, as determined by a Haake rheometer over a range of shear rates from 1 to 1000 sec.sup.1.

[0272] 15. Polymers suitable for use as a viscosity index improver (VII) or viscosity modifier (VM) for a lubricating oil composition comprising star diblock and triblock copolymers characterized by the formula:

##STR00021## [0273] and linear diblock and triblock copolymers characterized by the formula:

##STR00022## [0274] wherein D represents a block derived from at least one diene; PA represents a block derived from monoalkenyl arene; D represents a block derived from at least one diene; [0275] n represents the average number of arms per star diblock and triblock polymer formed by the reaction of 2 or more moles of a polyalkenyl coupling agent per mole of arms; [0276] and X represents a nucleus of a polyalkenyl coupling agent; and n has a value from about 4 to about 25; [0277] wherein PA has a number average molecular weight from about 10,000 Daltons to about 35,000 Daltons; [0278] wherein D has a number average molecular weight from about 20,000 Daltons to about 55,000 Daltons; [0279] wherein D has a number average molecular weight of about 15,000 Daltons or less; [0280] wherein a ratio of the number average molecular weight of D to the number average molecular weight of D is about 2.5:1 or greater; [0281] wherein a ratio of the number average molecular weight of PA to the number average molecular weight of D is about 1:1 or greater; and [0282] wherein the star diblock and triblock copolymers have a coupling efficiency greater than about 50%.

[0283] The disclosures of all patents, articles and other materials described herein are hereby incorporated, in their entirety, into this specification by reference. A description of a composition comprising, consisting of, or consisting essentially of multiple specified components, as presented herein and in the appended claims, should be construed to also encompass compositions made by admixing said multiple specified components. The principles, preferred embodiments, and modes of operation of the present disclosure have been described in the foregoing specification. What applicants submit is their disclosure, however, is not to be construed as limited to the particular embodiments disclosed, since the disclosed embodiments are regarded as illustrative rather than limiting. Changes may be made by those skilled in the art without departing from the spirit of the disclosure.