USE OF A DIESTER TO IMPROVE THE ANTI-WEAR PROPERTIES OF A LUBRICANT COMPOSITION

Abstract

The present invention relates to the use of a diester of the following formula (I):

R.sup.a—C(O)—O-—[C(R).sub.2].sub.n-O).sub.s-C(O)-R.sup.b   (I),

as an additive to improve the anti-wear properties of a lubricant composition comprising one or more anti-wear additive(s).

Claims

1-11. (canceled)

12. A method of improving the anti-wear properties of a lubricant composition comprising one or more anti-wear additives, the method comprising adding to the lubricant composition a diester represented by the following formula (I):
R.sup.a—C(O)—O—([C(R).sub.2].sub.n-O).sub.s-C(O)—R.sup.b   (I), wherein: R represent, independently of one another, a hydrogen atom, or a linear or branched (C.sub.1-C.sub.5)alkyl group; s has a value of 1 or 2; n has a value of 1, 2 or 3, wherein when s is 2, n may be identical or different from s; and R.sup.a and R.sup.b are independently selected from saturated or unsaturated, linear or branched, hydrocarbon-containing groups having a linear chain of 2 to 11 carbon atoms; wherein when s and n both have a value of 2, at least one of the R groups represents a linear or branched (C.sub.1-C.sub.5)alkyl group; and wherein when s has a value of 1 and n has a value of 3, at least one of the R groups bound to the carbon in the beta position of the oxygen atoms of the ester functions represents a hydrogen atom.

13. The method of claim 12, wherein the diester of formula (I) is added to the lubricant composition in an amount ranging from 1 wt. % to 30 wt. %, relative to the total weight of the lubricant composition.

14. The method of claim 12, wherein the one or more anti-wear additives are selected from zinc dialkyldithiophosphates represented by the formula:
Zn((SP(S)(OR)(OR′)).sub.2, wherein, R and R′ are independently selected from linear or branched alkyl groups comprising from 1 to 18 carbon atoms.

15. The method of claim 12, wherein the lubricant composition comprises 0.01 wt. % to 6 wt. % of the one or more anti-wear additives, relative to the total weight of the lubricant composition.

16. The method of claim 12, further comprising adding the lubricant composition to the engine of a vehicle.

17. The method of claim 12, wherein the lubricant composition comprises at least one base oil selected from the oils of group II, III, or IV of the API classification.

18. The method of claim 12, wherein the lubricant composition is of a grade according to the SAEJ300 classification defined by the formula (X)W(Y), wherein X represents 0 or 5; and Y represents an integer from 4 to 30.

19. The method of claim 12, wherein the lubricant composition further comprises one or more additives selected from friction modifying additives, extreme pressure additives, detergents, antioxidants, viscosity index improvers, pour point depressants, dispersants, antifoaming agents, thickeners, or mixtures thereof.

20. A method of improving the anti-wear properties of a lubricant composition comprising one or more anti-wear additives, the method comprising adding to the lubricant composition a diester represented by the following formula (I′):
R.sup.a—C(O)—O—([C(R).sub.2].sub.n-O)-([C(R′).sub.2].sub.m-O).sub.s-1-C(O)-R.sup.b   (I′), wherein: R and R′ are independently selected from a hydrogen atom or a linear or branched (C.sub.1-C.sub.5)alkyl group; s has a value of 1 or 2; n has a value of 2; m has a value of 2; and R.sup.a and R.sup.b are independently selected from saturated or unsaturated, linear or branched, hydrocarbon-containing groups having a linear chain of 2 to 11 carbon atoms; wherein when s has a value of 2, at least one of the R or R′ groups represents a linear or branched (C.sub.1-C.sub.5)alkyl group.

21. The method of claim 20, wherein: s has a value of 2, one of the R groups represents a linear or branched (C.sub.1-C.sub.5)alkyl group and the other R group represents a hydrogen atom; and one of the R′ groups represents a linear or branched (C.sub.1-C.sub.5)alkyl group and the other R′ group represents a hydrogen atom.

22. The method of claim 20, wherein: s has a value of 1, and one of the R groups represents a linear or branched (C.sub.1-C.sub.5)alkyl group and the other R group represents a hydrogen atom.

23. The method of claim 20, wherein the diester of formula (I′) is added to the lubricant composition in an amount ranging from 1 wt. % to 30 wt. %, relative to the total weight of the lubricant composition.

24. The method of claim 20, wherein the one or more anti-wear additives are selected from zinc dialkyldithiophosphates represented by the formula:
Zn((SP(S)(OR)(OR′)).sub.2, wherein R and R′ are independently selected from linear or branched alkyl groups comprising from 1 to 18 carbon atoms.

25. The method of claim 20, wherein the lubricant composition comprises from 0.01 wt. % to 6 wt. % of the one or more anti-wear additives, relative to the total weight of the lubricant composition.

26. The method of claim 20, further comprising adding the lubricant composition to the engine of a vehicle.

27. The method of claim 20, wherein the lubricant composition comprises at least one base oil selected from the oils of group II, III, or IV of the API classification.

28. The method of claim 20, wherein the lubricant composition is of a grade according to the SAEJ300 classification defined by the formula (X)W(Y), wherein X represents 0 or 5, and Y represents an integer from 4 to 30.

29. The method of claim 20, wherein the lubricant composition further comprises one or more additives selected from friction modifying additives, extreme pressure additives, detergents, antioxidants, viscosity index improvers, pour point depressants, dispersants, antifoaming agents, thickeners, or mixtures thereof.

Description

EXAMPLES

Example 1

Preparation of Lubricant Compositions Comprising a Diester Required According to the Invention and of Comparative Compositions

[0168] Lubricant compositions according to the invention (I1 and I2), using a diester of formula (I), and comparative compositions (C.sub.1 and C.sub.2), without a diester of formula (I), were formulated with the components and amounts (expressed in percentage by weight) indicated in Table 1 below.

[0169] The lubricant compositions are obtained by simple mixing of the following components at room temperature: [0170] Base oil of group III (KV100=4.2 mm.sup.2/s, KV40=19.1 mm.sup.2/s, VI of 126) available commercially for example from the company SK Lubricants under the trade name Yubase® 4, [0171] Conventional additive package 1 comprising an anti wear additive (zinc bis(dithiophosphate) and bis[O,O-bis(2-ethylhexyl)], for example marketed under the name OLOA® 269R), antioxidants, a friction modifier, a dispersant and detergents, [0172] Conventional additive package 2 comprising an antiwear additive (zinc bis[O-(1,3-dimethylbutyl)] bis[O-(isopropyl)] bis(dithiophosphate)), antioxidants, a friction modifier, a dispersant and detergents, [0173] A polymethacrylate comb polymer available commercially from the company Evonik under the trade name Viscoplex® V3-200, and optionally [0174] A diester of formula (I) according to the invention, obtained by an esterification reaction between dipropylene glycol and at least two nonanoic fatty acids.

TABLE-US-00002 TABLE 1 Compositions according Comparative to the invention compositions I1 I2 C1 C2 Additive package 1 12.2 12.2 Additive package 2 12.2 12.2 PMA polymer 4.7 4.7 4.7 4.7 Base oil 68.1 68.1 83.1 83.1 Ester of formula (I) of 15 15 0 0 the invention

[0175] The characteristics of the compositions thus prepared are presented in the following Table 2.

TABLE-US-00003 TABLE 2 Compositions I1 I2 C1 C2 HTHS.sup.(1) 2.59 2.60 2.58 2.57 KV40 (mm.sup.2/s).sup.(2) 31.14 31.07 32.32 32.09 KV100 (mm.sup.2/s).sup.(3) 7.92 7.92 7.39 7.42 VI.sup.(4) 243 244 206 209 .sup.(1)high-temperature, high-shear (HTHS) viscosity measurement, at shear of 10.sup.6 s.sup.−1 and at 150° C. by the standardized method ASTM D4683; .sup.(2)(3)kinematic viscosity at 40° C. (KV40) and at 100° C. (KV100) measured according to standard ASTM D445-97; .sup.(4)viscosity index (VI), measured according to standard ASTM D2270-93

Example 2

Evaluation of the Antiwear Properties

Method of Evaluation

[0176] This evaluation is based on a procedure according to standard ASTM D2670, requiring the use of a FALEX tribometer, in the following test conditions. [0177] test specimens: FALEX steel [0178] grinding time: 300 s; [0179] test duration: 180 min; [0180] grinding load: 445 N; [0181] test load: 1335 N; [0182] speed: 290 rev/min; [0183] room temperature.

[0184] The test results are presented in Table 3 below, and are expressed more specifically in uni; the lower the value obtained, the better are the antiwear properties of the composition evaluated.

TABLE-US-00004 TABLE 3 Compositions I1 I2 C1 C2 Wear (μm) 24 41 95 97 Pin mass loss vés (mg) 3 18 56 57 Test end temp. (° C.) 80 103 119 134 Mean torque at end of 40 80 105 109 test (Ncm)

[0185] The results show that the addition of a diester of formula (I) according to the invention to the lubricant compositions makes it possible to improve their antiwear properties significantly.