Lubricant compositions containing hydroxy carboxylic acid and hydroxy polycarboxylic acid esters

1. A composition comprising:

(A) a lubricant; and

(B) from 0.01 to 5 wt % of at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester having the following generic formula:

wherein: R 3 is selected from the group consisting of C 1 -C 18 linear or branched alkyl, C 1 -C 18 linear or branched alkenyl, alkoxyalkyl, hydroxyalkyl, aryl, and benzyl; and

X— is selected from the group consisting of

wherein:

R 1 is selected from the group consisting of hydrogen, CH 2 CO 2 R 3 , CH(OH)CO 2 R 3 , alkyl, aryl, alkoxyalkyl, and alkaryl;

R 2 is selected from the group consisting of hydrogen, alkyl, and CH 2 CO 2 R 3 ; provided that:

if R 1 is CH 2 CO 2 R 3 , then R 2 is hydrogen or CH 2 CO 2 R 3 ;

if R 1 is CH(OH)CO 2 R 3 , then R 2 is hydrogen;

if R 1 is alkyl, aryl, alkoxyalkyl, or alkaryl, then R 2 is hydrogen or alkyl;

R 4 is selected from the group consisting of hydrogen, alkyl, aryl, and CH 2 CO 2 R 3 ; and

R 5 and R 6 are independently selected from the group consisting of hydrogen, alkyl, and aryl;

and

(C) from 0.01 to 2 wt % of at least one phosphorus-containing additive.

2. The composition of claim 1 wherein the hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester is selected from the group consisting of citrates, tartrates, malates, lactates, mandelates, glycolates, hydroxy propionates, hydroxyglutarates, and mixtures thereof.

3. The composition of claim 2 wherein the hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester is trialkyl citrate.

4. The composition of claim 3 wherein the trialkyl citrate is selected from the group consisting of triethyl citrate, tributyl citrate, and mixtures thereof.

5. A method for improving the anti-fatigue, anti-wear, and extreme pressure properties of lubricants comprising adding to said lubricants

(A) from 0.01 to 5 wt % of at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester having the following generic formula:

wherein: R 3 is selected from the group consisting of C 1 -C 18 linear or branched alkyl, C 1 -C 18 linear or branched alkenyl, alkoxyalkyl, hydroxyalkyl, aryl, and benzyl; and

X— is selected from the group consisting of

wherein:

R 1 is selected from the group consisting of hydrogen, CH 2 CO 2 R 3 , CH(OH)CO 2 R 3 , alkyl, aryl, alkoxyalkyl, and alkaryl;

R 2 is selected from the group consisting of hydrogen, alkyl, and CH 2 CO 2 R 3 ; provided that:

if R 1 is CH 2 CO 2 R 3 , then R 2 is hydrogen or CH 2 CO 2 R 3 ;

if R 1 is CH(OH)CO 2 R 3 , then R 2 is hydrogen;

if R 1 is alkyl, aryl, alkoxyalkyl, or alkaryl, then R 2 is hydrogen or alkyl;

R 4 is selected from the group consisting of hydrogen, alkyl, aryl, and CH 2 CO 2 R 3 ; and

R 5 and R 6 are independently selected from the group consisting of hydrogen, alkyl, and aryl; and

(B) from 0.01 to 2 wt % of at least one phosphorus-containing additive.

6. The method of claim 5 wherein the hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester is selected from the group consisting of citrates, tartrates, malates, lactates, mandelates, glycolates, hydroxy propionates, hydroxyglutarates, and mixtures thereof.

7. The method of claim 6 wherein the ester is selected from the group consisting of triethyl citrate, tributyl citrate, and mixtures thereof.

8. The composition of claim 1 , wherein the combination of said at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester and said phosphorus-containing additive are present in the range from 0.2 to 2.0 wt %.

9. The composition of claim 1 , wherein said at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester is present in the range from 0.5 to 1.0 wt %.

10. The composition of claim 1 , wherein said phosphorus-containing additive is present in the range from 0.25 to 0.75 wt %.

11. The method of claim 5 , wherein the combination of said at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester and said phosphorus-containing additive are present in the range from 0.2 to 2.0 wt %.

12. The method of claim 5 , wherein said at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester is present in the range from 0.5 to 1.0 wt %.

13. The method of claim 5 , wherein said phosphorus-containing additive is present in the range from 0.25 to 0.75 wt %.

14. The method of claim 5 , wherein said phosphorus-containing additive is selected from the group consisting of zinc dialkyldithiophosphate, zinc diaryldithiophosphate, zinc alkylaryldithiophosphate, monohydrocarbyl dihydrogen phosphites, dihydrocarbyl hydrogen phosphites, trihydrocarbyl phosphites, diphosphites, triphosphites, polyphosphites, dithiophosphates, trithiophosphates, monohydrocarbyl dihydrogen phosphates, dihydrocarbyl hydrogen phosphates, trihydrocarbyl phosphates, amine phosphates, phosphonites, diphosphonites, and phosphorothionates.

15. The method of claim 5 , wherein the phosphorus-containing additive is a zinc dihydrocarbyldithiophosphate of formula (II):

wherein n is 2 and R 2 and R 3 are independently selected from the group consisting of alkyl, cycloalkyl, aralkyl, and alkaryl.

16. The method of claim 5 , wherein said phosphorus-containing additive is selected from the group consisting of dibutyl phosphite, dihexyl phosphite, dicyclohexyl phosphite, diisodecyl phosphite, di-n-octylphosphite, diphenyl isodecyl phosphite, diphenyl phosphite, di-n-octyl phosphite, dioleyl hydrogen phosphite, dimethylphenyl phosphite, ethyl hexyl diphenyl phosphite, phenyl diisodecyl phosphite, triisodecyl phosphite, triisoocytyl phosphite, trilauryl phosphite, triphenyl phosphite, tris(dipropyleneglycol)phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(5-norbornene-2-methyl)phosphite, tris(tridecyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphites, heptakis(dipropyleneglycol)triphosphite, tetraphenyl dipropyleneglycol diphosphite, tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphite, poly(dipropyleneglycol)phenyl phosphite, poly 4,4′isopropylidenediphenol-C 12 -C 15 alcohol phosphite, alkyl (C 10 ) bisphenol A phosphite, alkyl (C 12 -C 15 ) bisphenol A phosphite, tris(dipropyleneglycol)phosphite, phenyl neopentylene glycol phosphite, 2,4,6-tri-t-butylphenyl-2-butyl-2-ethyl-1,3 propanediol phosphite; 2,2-methylenebis(4,6-di-t-butylphenyl) 2-ethylhexyl phosphite, trilauryl trithiophosphite, tributyl phosphate, triphenyl phosphate, tritolyl phosphate, triphenyl phosphorothionate, tris(nonylphenyl) phosphorothionate and tris(butylphenyl)phosphorothionate.

17. The composition of claim 1 , wherein said phosphorus-containing additive is selected from the group consisting of zinc dialkyldithiophosphate, zinc diaryldithiophosphate, zinc alkylaryldithiophosphate, monohydrocarbyl dihydrogen phosphites, dihydrocarbyl hydrogen phosphites, trihydrocarbyl phosphites, diphosphites, triphosphites, polyphosphites, dithiophosphates, trithiophosphates, monohydrocarbyl dihydrogen phosphates, dihydrocarbyl hydrogen phosphates, trihydrocarbyl phosphates, amine phosphates, phosphonites, diphosphonites, and phosphorothionates.

18. The composition of claim 1 , wherein the phosphorus-containing additive is a zinc dihydrocarbyldithiophosphate of formula (II):

wherein n is 2 and R 2 and R 3 are independently selected from the group consisting of alkyl, cycloalkyl, aralkyl, and alkaryl.

19. The composition of claim 1 , wherein said phosphorus-containing additive is selected from the group consisting of dibutyl phosphite, dihexyl phosphite, dicyclohexyl phosphite, diisodecyl phosphite, di-n-octylphosphite, diphenyl isodecyl phosphite, diphenyl phosphite, di-n-octyl phosphite, dioleyl hydrogen phosphite, dimethylphenyl phosphite, ethyl hexyl diphenyl phosphite, phenyl diisodecyl phosphite, triisodecyl phosphite, triisoocytyl phosphite, trilauryl phosphite, triphenyl phosphite, tris(dipropyleneglycol)phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(5-norbornene-2-methyl)phosphite, tris(tridecyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphites, heptakis(dipropyleneglycol)triphosphite, tetraphenyl dipropyleneglycol diphosphite, tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphite, poly(dipropyleneglycol)phenyl phosphite, poly 4,4′isopropylidenediphenol-C 12 -C 15 alcohol phosphite, alkyl (C 10 ) bisphenol A phosphite, alkyl (C 12 -C 15 ) bisphenol A phosphite, tris(dipropyleneglycol)phosphite, phenyl neopentylene glycol phosphite, 2,4,6-tri-t-butylphenyl-2-butyl-2-ethyl-1,3 propanediol phosphite; 2,2-methylenebis(4,6-di-t-butylphenyl) 2-ethylhexyl phosphite, trilauryl trithiophosphite, tributyl phosphate, triphenyl phosphate, tritolyl phosphate, triphenyl phosphorothionate, tris(nonylphenyl)phosphorothionate and tris(butylphenyl)phosphorothionate.

20. A composition comprising:

(A) a lubricant; and

(B) from 0.01 to 5 wt % of at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester having the following generic formula:

wherein: R 3 is selected from the group consisting of C 1 -C 18 linear or branched alkyl, C 1 -C 18 linear or branched alkenyl, alkoxyalkyl, hydroxyalkyl, aryl, and benzyl; and

X— is selected from the group consisting of

wherein:

R 1 is selected from the group consisting of hydrogen, CH 2 CO 2 R 3 , CH(OH)CO 2 R 3 , alkyl, aryl, alkoxyalkyl, and alkaryl;

R 2 is selected from the group consisting of hydrogen, alkyl, and CH 2 CO 2 R 3 ; provided that:

if R 1 is CH 2 CO 2 R 3 , then R 2 is hydrogen or CH 2 CO 2 R 3 ;

if R 1 is CH(OH)CO 2 R 3 , then R 2 is hydrogen;

if R 1 is alkyl, aryl, alkoxyalkyl, or alkaryl, then R 2 is hydrogen or alkyl;

R 4 is selected from the group consisting of hydrogen, alkyl, aryl, and CH 2 CO 2 R 3 ;

R 5 and R 6 are independently selected from the group consisting of hydrogen, alkyl, and aryl; and

R 7 , R 8 , R 9 , and R 10 are independently selected from the group consisting of hydrogen, CO 2 R 3 , alkyl, and fused aryl; and

(C) from 0.01 to 2 wt % of at least one phosphorus-containing additive selected from the group consisting of dibutyl phosphite, dihexyl phosphite, dicyclohexyl phosphite, diisodecyl phosphite, di-n-octylphosphite, diphenyl isodecyl phosphite, diphenyl phosphite, di-n-octyl phosphite, dioleyl hydrogen phosphite, dimethylphenyl phosphite, ethyl hexyl diphenyl phosphite, phenyl diisodecyl phosphite, triisodecyl phosphite, triisoocytyl phosphite, trilauryl phosphite, triphenyl phosphite, tris(dipropyleneglycol)phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(5-norbornene-2-methyl)phosphite, tris(tridecyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphites, heptakis(dipropyleneglycol)triphosphite, tetraphenyl dipropyleneglycol diphosphite, tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphite, poly(dipropyleneglycol) phenyl phosphite, poly 4,4′isopropylidenediphenol-C 12 -C 15 alcohol phosphite, alkyl (C 10 ) bisphenol A phosphite, alkyl (C 12 -C 15 ) bisphenol A phosphite, tris(dipropyleneglycol)phosphite, phenyl neopentylene glycol phosphite, 2,4,6-tri-t-butylphenyl-2-butyl-2-ethyl-1,3 propanediol phosphite; 2,2-methylenebis(4,6-di-t-butylphenyl) 2-ethylhexyl phosphite, trilauryl trithiophosphite, tributyl phosphate, triphenyl phosphate, tritolyl phosphate, triphenyl phosphorothionate, tris(nonylphenyl)phosphorothionate and tris (butylphenyl)phosphorothionate.

21. A method for improving the anti-fatigue, anti-wear, and extreme pressure properties of lubricants comprising adding to said lubricants

(A) from 0.01 to 5 wt % of at least one hydroxy carboxylic acid ester or hydroxy polycarboxylic acid ester having the following generic formula:

wherein: R 3 is selected from the group consisting of C 1 -C 18 linear or branched alkyl, C 1 -C 18 linear or branched alkenyl, alkoxyalkyl, hydroxyalkyl, aryl, and benzyl; and

X— is selected from the group consisting of

wherein:

R 1 is selected from the group consisting of hydrogen, CH 2 CO 2 R 3 , CH(OH)CO 2 R 3 , alkyl, aryl, alkoxyalkyl, and alkaryl;

R 2 is selected from the group consisting of hydrogen, alkyl, and CH 2 CO 2 R 3 ; provided that:

if R 1 is CH 2 CO 2 R 3 , then R 2 is hydrogen or CH 2 CO 2 R 3 ;

if R 1 is CH(OH)CO 2 R 3 , then R 2 is hydrogen;

if R 1 is alkyl, aryl, alkoxyalkyl, or alkaryl, then R 2 is hydrogen or alkyl;

R 4 is selected from the group consisting of hydrogen, alkyl, aryl, and CH 2 CO 2 R 3 ; and

R 5 and R 6 are independently selected from the group consisting of hydrogen, alkyl, and aryl; and

R 7 , R 8 , R 9 , and R 10 are independently selected from the group consisting of hydrogen, CO 2 R 3 , alkyl, and fused aryl; and

(B) from 0.01 to 2 wt % of at least one phosphorus-containing additive selected from the group consisting of dibutyl phosphite, dihexyl phosphite, dicyclohexyl phosphite, diisodecyl phosphite, di-n-octylphosphite, diphenyl isodecyl phosphite, diphenyl phosphite, di-n-octyl phosphite, dioleyl hydrogen phosphite, dimethylphenyl phosphite, ethyl hexyl diphenyl phosphite, phenyl diisodecyl phosphite, triisodecyl phosphite, triisoocytyl phosphite, trilauryl phosphite, triphenyl phosphite, tris(dipropyleneglycol)phosphite, tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(5-norbornene-2-methyl)phosphite, tris(tridecyl)phosphite, bis-2,4-di-t-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-t-butyl4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphites, heptakis(dipropyleneglycol)triphosphite, tetraphenyl dipropyleneglycol diphosphite, tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphite, poly(dipropyleneglycol)phenyl phosphite, poly 4,4′isopropylidenediphenol-C 12 -C 15 alcohol phosphite, alkyl (C 10 ) bisphenol A phosphite, alkyl (C 12 -C 15 ) bisphenol A phosphite, tris(dipropyleneglycol)phosphite, phenyl neopentylene glycol phosphite, 2,4,6-tri-t-butylphenyl-2-butyl-2-ethyl-1,3 propanediol phosphite; 2,2-methylenebis(4,6-di-t-butylphenyl) 2-ethylhexyl phosphite, trilauryl trithiophosphite, tributyl phosphate, triphenyl phosphate, tritolyl phosphate, triphenyl phosphorothionate, tris(nonylphenyl)phosphorothionate and tris(butylphenyl)phosphorothionate.