Organic Anti-Wear Additive Compositions for Lubricants

Abstract

Improved organic anti-wear additive compositions are disclosed containing certain citric acid esters, e.g., mixtures comprising citrate oligomers, and fatty acid alkanolamides. The combination exhibits excellent and synergistic anti-wear activity in lubricants. The compositions of the invention beneficially allow one to reduce amounts of zinc and phosphorus that are often used in lubricants, while boosting anti-wear performance and maintaining, and often enhancing, friction reduction properties.

Claims

1. An antiwear additive composition comprising: (a) a citrate compound of formula II ##STR00012## a citrate compound of formula III ##STR00013## a mixture of citrate compounds of formula II and formula III, wherein: n is from 1 to 20; R is C.sub.1-18 alkyl; C.sub.1-18 alkyl substituted by a carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or the heterocycle may be substituted by one or more C.sub.1-12 alkyl or alkyloxy; C.sub.2-18 alkyl interrupted by one or more O, carbonyl, carbonyloxy and/or substituted by OH; C.sub.2-18 alkyl interrupted by one or more O, carbonyl or carbonyloxy and substituted by a carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; or a carbocycle comprising 5 to 12 carbon atoms, or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; and R is C.sub.2-18 alkylene; C.sub.2-18 alkylene interrupted by one or more O, carbonyl or carbonyloxy and/or substituted by OH, carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; or said alkylene, interrupted alkylene or substituted alkylene interrupted by a carbocycle comprising 5 to 12 carbon atoms, or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; wherein each R and each R may be the same or different from any other R or R; and (b) a fatty acid alkanolamide of formula IV ##STR00014## wherein n is 1 or 2; when n is 1, m is 1; when n is 2, m is 0, R.sup.1 is H or C.sub.1-12 alkyl, G is H or C.sub.1-6 alkyl, and R.sup.2 is selected from C.sub.7-23 alkyl or alkenyl; wherein the ratio by weight of the citrate component (a) to the fatty acid alkanolamide component (b) is from 8:1 to 1:8.

2. The antiwear additive composition according to claim 1, wherein the composition comprises more than one citrate compound of formula III which differ by having different values of n.

3. The antiwear additive composition according to claim 1, wherein component (a) further comprises a citrate compound of formula I ##STR00015## wherein R is as described for formula II and III.

4. The antiwear additive composition according to claim 3, wherein the additive composition comprises at least one citrate compound of formula I, at least one citrate compound of formula II, and at least one citrate compound of formula III, wherein n is from 1 to 5; R is C.sub.1-12 alkyl or C.sub.2-12 alkyl interrupted by one or more O, and R is C.sub.2-12 alkylene, or said alkylene interrupted by one or more O.

5. An antiwear additive composition comprising: (a) a citrate compound of formula I ##STR00016## wherein R is a carbocycle comprising 5 to 12 carbon atoms, or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; C.sub.1-6 alkyl substituted by a carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or the heterocycle may be substituted by one or more C.sub.1-12 alkyl or alkyloxy; C.sub.6-18 alkyl interrupted by one or more O, carbonyl, or carbonyloxy and/or substituted by OH; or C.sub.6-18 alkyl interrupted by one or more O, carbonyl, or carbonyloxy and substituted by OH, carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; and (b) a fatty acid alkanolamide of formula IV ##STR00017## wherein n is 1 or 2; when n is 1, m is 1; when n is 2, m is 0, R.sup.1 is H or C.sub.1-12 alkyl, G is H or C.sub.1-6 alkyl, and R.sup.2 is selected from C.sub.7-23 alkyl or alkenyl; wherein the ratio by weight of the citrate component (a) to the fatty acid alkanolamide component (b) is from 8:1 to 1:8.

6. The antiwear additive composition according to claim 1, wherein the fatty acid alkanolamide is a compound of formula V: ##STR00018## wherein R 1 is H or C.sub.1-12 alkyl, and R.sup.2 is selected from C.sub.7-23 alkyl or alkenyl.

7. The antiwear additive composition according to claim 6, wherein R.sup.1 is chosen from C.sub.1-4 alkyl.

8. (canceled)

9. The antiwear additive composition according to claim 6, wherein the fatty acid alkanolamide is a mixture of compounds of formula V, wherein about 15 to about 45% by weight of the fatty acid alkanolamide are compounds where R.sup.2 is C.sub.15 alkyl or alkenyl, about 40 to about 80% by weight of the fatty acid alkanolamide are compounds where R.sup.2 is C.sub.17 alkyl or alkenyl, and 0 to about 15% by weight of the fatty acid alkanolamide are compounds where R.sup.2 is C.sub.7-14, C.sub.16 or C.sub.18-19 alkyl or alkenyl.

10. The antiwear additive composition according to claim 6, wherein the fatty acid alkanolamide is prepared by reacting a di(hydroxyalkyl) amine with carboxylic acids or carboxylic acid derivatives from canola oil, corn oil, coconut oil, sunflower oil, soybean oil, lard, palm oil, beef tallow, cocoa butter, or illipe.

11. (canceled)

12. (canceled)

13. A lubricant composition comprising: A) a lubricating oil, B) from 0.1 to 5 wt %, based on the weight of the lubricant composition, of a citrate compound of formula II ##STR00019## a citrate compound of formula III ##STR00020## a mixture of citrate compounds of formula II and formula III, wherein: n is from 1 to 20; R is C.sub.1-18 alkyl; C.sub.1-18 alkyl substituted by a carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or the heterocycle may be substituted by one or more C.sub.1-12 alkyl or alkyloxy; C.sub.2-18 alkyl interrupted by one or more O, carbonyl, carbonyloxy and/or substituted by OH; C.sub.2-18 alkyl interrupted by one or more O, carbonyl or carbonyloxy and substituted by a carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; or a carbocycle comprising 5 to 12 carbon atoms, or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; and R is C.sub.2-18 alkylene; C.sub.2-18 alkylene interrupted by one or more O, carbonyl or carbonyloxy and/or substituted by OH, carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; or said alkylene, interrupted alkylene or substituted alkylene interrupted by a carbocycle comprising 5 to 12 carbon atoms, or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; wherein each R and each R may be the same or different from any other R or R; and C) from 0.1 to 5 wt %, based on the weight of the lubricant composition, of a fatty acid alkanolamide of formula IV ##STR00021## wherein n is 1 or 2; when n is 1, m is 1; when n is 2, m is 0, R.sup.1 is H or C.sub.1-12 alkyl, G is H or C.sub.1-6 alkyl, and R.sup.2 is selected from C.sub.7-23 alkyl or alkenyl.

14. The lubricant composition according to claim 13, wherein the ratio by weight of the citrate component B) to the fatty acid alkanolamide component C) is from 8:1 to 1:8.

15. The lubricant composition according to claim 13, wherein the composition comprises more than one citrate compound of formula III which differ by having different values of n.

16. The lubricant composition according to claim 13, further comprising a citrate compound of formula I ##STR00022## wherein R is as described for formula II and III, and the wt % of all citrate compounds of formulas I, II and III combined is from 0.1 to 5 wt %, based on the weight of the lubricant composition.

17. The lubricant composition according to claim 16, wherein the composition comprises at least one citrate compound of formula I, at least one citrate compound of formula II, and at least one citrate compound of formula III, wherein n is from 1 to 5; R is C.sub.1-12 alkyl or C.sub.2-12 alkyl interrupted by one or more O, and R is C.sub.2-12 alkylene, or said alkylene interrupted by one or more O.

18. A lubricant composition comprising: A) a lubricating oil, B) from 0.1 to 5 wt %, based on the weight of the lubricant composition, of a citrate compound of formula I ##STR00023## wherein R is a carbocycle comprising 5 to 12 carbon atoms, or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; C.sub.1-6 alkyl substituted by a carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or the heterocycle may be substituted by one or more C.sub.1-12 alkyl or alkyloxy; C.sub.6-18 alkyl interrupted by one or more O, carbonyl, or carbonyloxy and/or substituted by OH; or C.sub.6-18 alkyl interrupted by one or more O, carbonyl, or carbonyloxy and substituted by OH, carbocycle comprising 5 to 12 carbon atoms or a heterocycle comprising 3 to 11 carbon atoms and one or more heteroatoms selected from O, S and N, wherein the carbocycle or heterocycle may be substituted by C.sub.1-12 alkyl or alkyloxy; and C) from 0.1 to 5 wt %, based on the weight of the lubricant composition, of a fatty acid alkanolamide of formula IV ##STR00024## wherein n is 1 or 2; when n is 1, m is 1; when n is 2, m is 0, R.sup.1 is H or C.sub.1-12 alkyl, G is H or C.sub.1-6 alkyl, and R.sup.2 is selected from C.sub.7-23 alkyl or alkenyl.

19. The lubricant composition according to claim 18, wherein the ratio by weight of the citrate component B) to the fatty acid alkanolamide component C) is from 8:1 to 1:8.

20. The lubricant composition according to claim 13, wherein the fatty acid alkanolamide is a compound of formula V: ##STR00025## wherein R.sup.1 is H or C.sub.1-12 alkyl, and R.sup.2 is selected from C.sub.7-23 alkyl or alkenyl.

21. The lubricant composition according to claim 20, wherein R.sup.1 is chosen from C.sub.1-4 alkyl.

22. The lubricant composition according to claim 21, wherein R.sup.1 is methyl.

23. The lubricant composition according to claim 20, wherein the fatty acid alkanolamide is a mixture of compounds of formula V, wherein about 15 to about 45% by weight of the fatty acid alkanolamide are compounds where R.sup.2 is C.sub.15 alkyl or alkenyl, about 40 to about 80% by weight of the fatty acid alkanolamide are compounds where R.sup.2 is C.sub.17 alkyl or alkenyl, and 0 to about 15% by weight of the fatty acid alkanolamide are compounds where R.sup.2 is C.sub.7-14, C.sub.16 or C.sub.18-19 alkyl or alkenyl.

24. The lubricant composition according to claim 20, wherein the fatty acid alkanolamide is prepared by reacting a di(hydroxyalkyl) amine with carboxylic acids or carboxylic acid derivatives from canola oil, corn oil, coconut oil, sunflower oil, soybean oil, lard, palm oil, beef tallow, cocoa butter, or illipe.

25. (canceled)

26. (canceled)

27. The lubricant composition according to claim 13, further comprising D) zinc dialkyldithiophosphate (ZDDP).

28.-30. (canceled)

Description

EXAMPLES

Example 1

[0137] Citrate component (Citrate-1): [0138] Propane-1,2-diyl bis(dihexyl citrate) oligomers prepared by the reaction of citric acid, hexanol and 1,2-propanediol in the presence of an acid catalyst.

[0139] Fatty acid alkanolamide: [0140] Additin RC 3502 from LANXESS, which is a bis(2-hydoxypropyl) tallowamide.

[0141] Zinc dialkyldithiophosphate (ZDDP).

[0142] Lubricating oil: [0143] 5W-30 oil (fully formulated, but without any antiwear or friction modifier additives, STD).

[0144] Lubricant compositions containing the reference 5W-30 oil (STD) and the weight percentages of the additives shown in Table la were prepared and tested for anti-wear performance using ASTM D4172 four-ball wear testing where three steel hardened balls were placed in contact with the test fluid under 40 kg load and a fourth ball was rotated at 1200 rpm for 1 hour while the test sample was heated at 75 C. After the test, the wear scar diameter of each of the three captured stationary balls was measured in two perpendicular directions and the average wear scar (in mm) was reported.

TABLE-US-00001 TABLE 1a Inv/ Wear Comp Sample (mm) Comp. STD 0.774 Comp. STD + ZDDP (1 wt %) 0.453 Comp. STD + Citrate-1 (1 wt %) 0.406 Comp. STD + RC 3502 (1 wt %) 0.445 Inv. STD + Citrate-1 (0.5 wt %) + RC 3502 (0.5 wt %) 0.353

[0145] The results demonstrate a synergistic effect on antiwear performance of the combination of the citrate component with the alkanolamide component. That is, the antiwear activity of the combination was significantly enhanced relative to the activity of the citrate and fatty acid alkanolamide when each was tested alone, all at the same total load level.

[0146] Moreover, further enhancement in antiwear activity was exhibited by the three-way combination of the citrate, the fatty acid alkanolamide and ZDDP, as shown in Table 1b. The present invention therefore allows one to obtain excellent antiwear properties with a fully organic antiwear additive composition, and, if combined with ZDDP, achieves further enhanced antiwear performance, while at the same time allowing for reduced levels of the amount of ZDDP in the lubricant formulation.

TABLE-US-00002 TABLE 1b Inv/ Wear Comp Sample (mm) Comp. STD + Citrate-1 (0.5 wt %) + ZDDP (0.5 wt %) 0.307 Inv. STD + Citrate-1 (0.5 wt %) + RC 3502 (1 wt %) + 0.27 ZDDP (0.5 wt %)

[0147] Similar results are shown in the further Examples below.

Example 2

[0148] Lubricant compositions were prepared and tested according to Example 1, except the citrate component (Citrate-2) was butane-1,4-diyl bis(dihexyl citrate) oligomers prepared by the reaction of citric acid, hexanol and 1,4-butanediol in the presence of an acid catalyst. The samples and results are shown in Tables 2a and 2b.

TABLE-US-00003 TABLE 2a Inv/ Wear Comp Sample (mm) Comp. STD 0.743 Comp. STD + ZDDP (1 wt %) 0.448 Comp. STD + Citrate-2 (1 wt %) 0.396 Comp. STD + RC 3502 (1 wt %) 0.445 Inv. STD + Citrate-2 (0.5 wt %) + RC 3502 (0.5 wt %) 0.357

TABLE-US-00004 TABLE 2b Inv/ Wear Comp Sample (mm) Comp. STD + Citrate-2 (0.5 wt %) + ZDDP (0.5 wt %) 0.32 Inv. STD + Citrate-2 (0.5 wt %) + RC 3502 (1 wt %) + 0.308 ZDDP (0.5 wt %)

Example 3

[0149] Lubricant compositions were prepared and tested according to Example 1, except the citrate component (Citrate-3) was hexane-1,6-diyl bis(dihexyl citrate) oligomers prepared by the reaction of citric acid, hexanol and 1,6-hexanediol in the presence of an acid catalyst. The samples and results are shown in Tables 3a and 3b.

TABLE-US-00005 TABLE 3a Inv/ Wear Comp Sample (mm) Comp. STD 0.743 Comp. STD + ZDDP (1 wt %) 0.448 Comp. STD + Citrate-3 (1 wt %) 0.408 Comp. STD + RC 3502 (1 wt %) 0.445 Inv. STD + Citrate-3 (0.5 wt %) + RC 3502 (0.5 wt %) 0.340

TABLE-US-00006 TABLE 3b Inv/ Wear Comp Sample (mm) Comp. STD + Citrate-3 (0.5 wt %) + ZDDP (0.5 wt %) 0.332 Inv. STD + Citrate-3 (0.5 wt %) + RC 3502 (1 wt %) + 0.306 ZDDP (0.5 wt %)

Example 4

[0150] Lubricant compositions were prepared and tested according to Example 1, except the citrate component (Citrate-4) was ethane-1,2-diyl bis(dihexyl citrate) oligomers prepared by the reaction of citric acid, hexanol and 1,2-ethanediol in the presence of an acid catalyst. The samples and results are shown in Tables 4a and 4b.

TABLE-US-00007 TABLE 4a Inv/ Wear Comp Sample (mm) Comp. STD 0.743 Comp. STD + ZDDP (1 wt %) 0.453 Comp. STD + Citrate-4 (1 wt %) 0.426 Comp. STD + RC 3502 (1 wt %) 0.445 Inv. STD + Citrate-4 (0.5 wt %) + RC 3502 (0.5 wt %) 0.412

TABLE-US-00008 TABLE 4b Inv/ Wear Comp Sample (mm) Comp. STD + Citrate-4 (0.5 wt %) + ZDDP (0.5 wt %) 0.316 Inv. STD + Citrate-4 (0.5 wt %) + RC 3502 (1 wt %) + 0.292 ZDDP (0.5 wt %)

[0151] Although particular embodiments of the present invention have been illustrated and described, this description is not meant to be construed in a limiting sense. Various changes and modifications may be made without departing from the principle and scope of the present invention, which is defined by the appended claims.