Wet friction clutch—lubricant systems providing high dynamic coefficients of friction through the use of borated detergents

1. A wet friction clutch-lubricant system wherein a wet friction clutch having a cellulose-based friction lining having a surface coating of silica based particles, or a device including such a clutch, is lubricated with a lubricant composition comprising a major amount of oil of lubricating viscosity and minor effective amounts of (a) ashless dispersant; (b) organic phosphorus compound and (c) borated detergent, wherein said borated detergent comprises borated magnesium sulfonate detergent.

2. The wet friction clutch-lubricant system of claim 1 , wherein said clutch is included in a device, and said device is a vehicular automatic transmission.

3. The wet friction clutch-lubricant system of claim 2 , wherein said automatic transmission is of a type selected from the group consisting of stepped automatic transmissions, automated manual transmissions, continuously variable transmissions and dual clutch transmissions.

4. The wet friction clutch-lubricant system of claim 1 , wherein said borated magnesium sulfonate detergent comprises an overbased borated magnesium sulfonate detergent.

5. The wet friction clutch-lubricant system of claim 2 , wherein said organic phosphorus compound is selected from the group consisting of phosphites and thiophosphites(mono-alkyl, di-alkyl, tri-alkyl and partially hydrolyzed analogs thereof); phosphates and thiophosphates; amines treated with inorganic phosphorus; zinc dithiodiphosphates; amine phosphates; and combinations thereof.

6. The wet friction clutch-lubricant system of claim 5 , wherein said organic phosphorus compound is selected from the group consisting of mono-n-butyl-hydrogen-acid-phosphite; di-n-butyl-hydrogen phosphite; triphenyl phosphite; triphenyl thiophosphite; tri-n-butylphosphate; trilauryltrithiophosphite; dimethyl octadecenyl phosphonate, low molecular weight polyisobutenyl succinic anhydride polyamine dispersant post treated with H 3 PO 3 and H 3 BO 3 ; zinc (di-2-ethylhexyldithiophosphate); and combinations thereof.

7. The wet friction clutch-lubricant system of claim 5 , wherein said organic phosphorus compound is selected from the group consisting of esters of phosphoric and phosphorous acid.

8. The wet friction clutch-lubricant system of claim 2 , wherein said lubricant composition further comprises a minor effective amount of an auxiliary friction modifier.

9. The wet friction clutch-lubricant system of claim 8 , wherein said auxiliary friction modifier is selected from the group consisting of fatty phosphites; fatty acid amides; fatty epoxides; borated fatty epoxides; fatty amines; glycerol esters; borated glycerol esters; alkoxylated fatty amines; borated alkoxylated fatty amines; metal salts of fatty acids; sulfurized olefins; fatty imidazolines; condensation products of carboxylic acids and/or anhydrides and polyalkylene-polyamines; metal salts of alkyl salicylates; amine salts of alkylphosphoric acids; and combinations thereof.

10. A method of lubricating a wet friction clutch having a cellulose-based friction lining having a surface coating of silica based particles, or a device including such a clutch, comprising the steps of lubricating the clutch or device with a lubricant composition comprising a major amount of oil of lubricating viscosity and a minor effective amounts of (a) ashless dispersant; (b) organic phosphorus compound and (c) borated detergent, wherein said borated detergent comprises borated magnesium sulfonate detergent.

11. The method of claim 10 , wherein said clutch is included in a device, and said device is a vehicular automatic transmission.

12. The method of claim 11 , wherein said automatic transmission is of a type selected from the group consisting of stepped automatic transmissions, automated manual transmissions, continuously variable transmissions and dual clutch transmissions.

13. The method of claim 10 , wherein said borated magnesium sulfonate detergent comprises a borated overbased magnesium sulfonate detergent.

14. The method of claim 11 , wherein said organic phosphorus compound is selected from the group consisting of phosphites and thiophosphites (mono-alkyl, di-alkyl, tri-alkyl and partially hydrolyzed analogs thereof); phosphates and thiophosphates; amines treated with inorganic phosphorus; zinc dithiodiphosphates; amine phosphates; and combinations thereof.

15. The method of claim 14 , wherein said organic phosphorus compound is selected from the group consisting of mono-n-butyl-hydrogen-acid-phosphite; di-n-butyl-hydrogen phosphite; triphenyl phosphite; triphenyl thiophosphite; tri-n-butylphosphate; trilauryltrithiophosphite; dimethyl octadecenyl phosphonate, low molecular weight polyisobutenyl succinic anhydride polyamine post treated with H 3 PO 3 and H 3 BO 3 ; zinc (di-2-ethylhexyldithiophosphate); and combinations thereof.

16. The method of claim 14 , wherein said organic phosphorus compound is selected from the group consisting of esters of phosphoric and phosphorous acid.

17. The method of claim 11 , wherein said lubricant composition further comprises a minor effective amount of an auxiliary friction modifier.

18. The method of claim 17 , wherein said auxiliary friction modifier is selected from the group consisting of fatty phosphites; fatty acid amides; fatty epoxides; borated fatty epoxides; fatty amines; glycerol esters; borated glycerol esters; alkoxylated fatty amines; borated alkoxylated fatty amines; metal salts of fatty acids; sulfurized olefins; fatty imidazolines; condensation products of carboxylic acids and/or anhydrides and polyalkylene-polyamines; metal salts of alkyl salicylates; amine salts of alkylphosphoric acids; and combinations thereof.

19. A power transmission fluid comprising a major amount of oil of lubricating viscosity and minor effective amounts of (a) one or more ashless dispersants; (b) one or more organic phosphorus compound and (c) borated detergent, wherein said borated detergents comprises borated magnesium sulfonate detergent, and wherein said fluid has a TBN of less than 5.0 mg KOH/g (as measured in accordance with ASTM D-2896), a boron content of less than 200 ppm, and a phosphorus content of less than 500 ppm.

20. The power transmission fluid of claim 19 , wherein said borated magnesium sulfonate detergent comprises an overbased borated magnesium sulfonate detergent.

21. The power transmission fluid of claim 19 , wherein said organic phosphorus compound is selected from the group consisting of phosphites and thiophosphites(mono-alkyl, di-alkyl, tri-alkyl and partially hydrolyzed analogs thereof); phosphates and thiophosphates; amines treated with inorganic phosphorus; zinc dithiodiphosphates; amine phosphates; and combinations thereof.

22. The power transmission fluid of claim 21 , wherein said organic phosphorus compound is selected from the group consisting of mono-n-butyl-hydrogen-acid-phosphite; di-n-butyl-hydrogen phosphite; triphenyl phosphite; triphenyl thiophosphite; tri-n-butylphosphate; trilauryltrithiophosphite; dimethyl octadecenyl phosphonate, low molecular weight polyisobutenyl succinic anhydride polyamine dispersant post treated with H 3 PO 3 and H 3 BO 3 ; zinc (di-2-ethylhexyldithiophosphate); and combinations thereof.

23. The power transmission fluid of claim 21 , wherein said organic phosphorus compound is selected from the group consisting of esters of phosphoric and phosphorous acid.

24. The power transmission fluid of claim 19 , wherein said lubricant composition further comprises a minor effective amount of an auxiliary friction modifier.

25. The power transmission fluid of claim 24 , wherein said auxiliary friction modifier is selected from the group consisting of fatty phosphites; fatty acid amides; fatty epoxides; borated fatty epoxides; fatty amines; glycerol esters; borated glycerol esters; alkoxylated fatty amines; borated alkoxylated fatty amines; metal salts of fatty acids; sulfurized olefins; fatty imidazolines; condensation products of carboxylic acids and/or anhydrides and polyalkylene-polyamines; metal salts of alkyl salicylates; amine salts of alkylphosphoric acids; and combinations thereof.