Use of polyalkylmethacrylate polymer

1. A method of improving pump efficiency of a hydraulic pump, comprising:

operating said hydraulic pump with a hydraulic fluid comprising at least one base oil and a polyalkylmethacrylate polymer;

wherein the pump efficiency is improved compared to the pump efficiency when using a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer;

wherein an ISO viscosity grade of said hydraulic fluid is maintained compared to a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer; and

wherein said hydraulic fluid comprises 1-30% by weight of said polyalkylmethacrylate polymer.

2. A method of reducing energy consumption of a hydraulic pump, comprising:

operating said hydraulic pump with a hydraulic fluid comprising at least one base oil and a polyalkylmethacrylate polymer;

wherein the energy consumption is reduced compared to the energy consumption when using a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer;

wherein an ISO viscosity grade of said hydraulic fluid is maintained compared to a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer; and

wherein said hydraulic fluid comprises 1-30% by weight of said polyalkylmethacrylate polymer.

3. A method of decreasing friction and wear of moving parts, comprising:

contacting said moving parts with a lubricant comprising at least one base oil and a polyalkylmethacrylate polymer;

wherein the friction and wear are reduced compared to the friction and wear when using a lubricant which does not comprise said polyalkylmethacrylate polymer;

wherein an ISO viscosity grade of said hydraulic fluid is maintained compared to a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer; and

wherein said hydraulic fluid comprises 1-30% by weight of said polyalkylmethacrylate polymer.

4. A method of reducing erosion in a hydraulic system, comprising:

mixing at least one base oil with a polyalkylmethacrylate polymer, to obtain a hydraulic fluid;

contacting the hydraulic system with said hydraulic fluid to improve the air release of said hydraulic fluid and reduce the erosion in said hydraulic system;

wherein an ISO viscosity grade of said hydraulic fluid is maintained compared to a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer; and

wherein said hydraulic fluid comprises 1-30% by weight of said polyalkylmethacrylate polymer.

5. A method of preventing degradation of a hydraulic fluid in a hydraulic system, comprising:

mixing at least one base oil with a polyalkylmethacrylate polymer, to obtain a hydraulic fluid;

contacting the hydraulic system with said hydraulic fluid to improve the air release of said hydraulic fluid and prevent degradation of said hydraulic fluid in said hydraulic system;

wherein an ISO viscosity grade of said hydraulic fluid is maintained compared to a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer; and

wherein said hydraulic fluid comprises 1-30% by weight of said polyalkylmethacrylate polymer.

6. A reservoir of a hydraulic system, comprising:

a hydraulic fluid comprising at least one base oil and a polyalkylmethacrylate polymer,

wherein said reservoir is smaller than a reservoir comprising the same hydraulic fluid except without said polyalkylmethacrylate polymer;

wherein an ISO viscosity grade of said hydraulic fluid is maintained compared to a hydraulic fluid which does not comprise said polyalkylmethacrylate polymer; and

wherein said hydraulic fluid comprises 1-30% by weight of said polyalkylmethacrylate polymer.

7. The method according to claim 1 , wherein said ISO viscosity grade is in the range of 15 to 3200.

8. The method according to claim 1 , wherein said polyalkylmethacrylate polymer comprises at least 40% by weight methacrylate repeating units.

9. The method according to claim 1 , wherein said hydraulic fluid has a viscosity index according to ASTM D 2270 of at least 120.

10. The method according to claim 1 , wherein said polyalkylmethacrylate polymer has a molecular weight in the range of 10000-200000 g/mol.

11. The method according to claim 1 , wherein said polyalkylmethacrylate polymer comprises C 9 -C 24 methacrylate repeating units and C 1 -C 8 methacrylate repeating units.

12. The method according to claim 1 , wherein said polyalkylmethacrylate polymer comprises repeating units derived from dispersant monomers.

13. The method according to claim 1 , wherein said polyalkylmethacrylate polymer comprises repeating units derived from styrene.

14. The method according to claim 1 , wherein said polyalkylmethacrylate polymer comprises repeating units derived from ethoxylated and/or hydroxylated methacrylate monomers.

15. The method according to claim 1 , wherein said hydraulic fluid comprises antioxidants, corrosion inhibitors, defoamers or mixtures thereof.

16. The method according to claim 1 , wherein said hydraulic fluid comprises a mineral oil.

17. The method according to claim 1 , wherein said hydraulic fluid comprises at least one synthetic oil.

18. The method according to claim 17 , wherein said synthetic oil comprises a poly-alpha olefin, a carboxylic ester, a carboxylic diester, a polyol ester, a phosphate ester, a trialkyl phosphate ester, triaryl phosphate ester, alkyl aryl phosphate ester, a polyalkylene glycol or mixtures thereof.

19. The method according to claim 1 , wherein said polyalkylmethacrylate polymer is obtained by polymerizing a mixture of olefinically unsaturated monomers, said mixture comprising:

a) 0-100 wt %, based on a total weight of the ethylenically unsaturated monomers, of one or more ethylenically unsaturated ester compounds of formula (I)

wherein

R is hydrogen or methyl,

R 1 means a linear or branched alkyl residue with 1-8 carbon atoms,

R 2 and R 3 independently represent hydrogen or a group of the formula —COOR′, wherein R′ means hydrogen or a alkyl group with 1-8 carbon atoms,

b) 0-100 wt %, based on the total weight of the ethylenically unsaturated monomers, of one or more ethylenically unsaturated ester compounds of formula (II)

wherein

R is hydrogen or methyl,

R 4 means a linear or branched alkyl residue with 9-16 carbon atoms,

R 5 and R 6 independently are hydrogen or a group of the formula —COOR″, wherein R″ means hydrogen or an alkyl group with 9-16 carbon atoms,

c) 0-80 wt %, based on the total weight of the ethylenically unsaturated monomers, of one or more ethylenically unsaturated ester compounds of formula (III)

wherein

R is hydrogen or methyl,

R 7 means a linear ox branched alkyl residue with 17-40 carbon atoms,

R 8 and R 9 independently are hydrogen or a group of the formula —COOR′″, wherein R′″ means hydrogen or an alkyl group with 17-40 carbon atoms,

d) 0-50 wt %, based on the total weight of the ethylenically unsaturated monomers, of comonomers,

wherein at least 50 wt %, based on the total weight of the ethylenically unsaturated monomers, are methacrylates.

20. The method according to claim 19 , wherein said mixture of olefinically unsaturated monomers comprises 50 to 95% by weight of the component b).

21. The method according to claim 19 , wherein said mixture of olefinically unsaturated monomers comprises 1 to 30% by weight of the component a).

22. The method according to claim 1 , wherein said polyalkylmethacrylate polymer has a molecular weight in the range of 25000 g/mol-100000 g/mol.

23. The method according to claim 1 , wherein said hydraulic fluid comprises a mineral oil from API Group I, II, or III.

24. The method according to claim 1 , wherein said hydraulic fluid comprises at least one synthetic oil from API Group IV and V.