Compressor oils with high viscosity index

2:

• The method according to claim 1, wherein the polyalkyl methacrylate-based viscosity index improver comprises:
• (a) 0.2 wt. % of the methyl methacrylate;
• (b) 75 wt. % to 99.8 wt. % of the at least one C10-18 alkyl (meth)acrylate;
• and
• (c) 0 wt. % to 2 wt. % of the at least one straight-chained or branched C5-9 alkyl (meth)acrylate or the at least one straight-chained or branched C20-24 alkyl (meth)acrylate.

8:

• The method according to claim 1, wherein the compressor is a household or domestic refrigeration unit using isobutane or propane as refrigerant, the method comprising:
• operating the refrigeration unit with the compressor oil, wherein the compressor oil comprises:
• (i) 1 wt. % to 10 wt. % of the polyalkyl methacrylate-based viscosity index improver comprising:
• (a) 0.2 wt. % to 25 wt. % of the methyl methacrylate;
• and
• (b) 75 wt. % to 99.8 wt. % of the at least one C10-18 alkyl (meth)acrylate,
• wherein the weight average molecular weight (Mw) of the polyalkyl (meth)acrylate-based viscosity index improver is in a range of 5,000 g/mol to 200.000 g/mol;
• (ii) 90 wt. % to 99 wt. % of an API group IV or V base oil, or a mixture thereof;
• and
• (iii) 0 wt. % to 2.5 wt. % of a zinc-free performance package comprising at least an antiwear agent, an anticorrosion agent, and an antioxidant,
• wherein the compressor oil has a kinematic viscosity at 40° C. in the range of 2.88 and 7.48 cSt and a viscosity index of at least 140.

12:

• The method according to claim 1, wherein the compressor is an air compressor, the method comprising:
• operating the air compressor with the compressor oil, wherein the compressor oil comprises:
• (i) 1 wt. % to 20 wt. % of the polyalkyl methacrylate-based viscosity index improver comprising:
• (a) 0.2 wt. % to 25 wt. % of the methyl methacrylate;
• (b) 75 wt. % to 99.8 wt. % of the at least one C10-18 alkyl (meth)acrylate;
• and
• (c) 0 wt. % to 2 wt. % of the at least one straight-chained or branched C5-9 alkyl (meth)acrylate or the at least one straight-chained or branched C20-24 alkyl (meth)acrylate,
• wherein the weight average molecular weight (Mw) of the polyalkyl (meth)acrylate-based viscosity index improver is in the range of 5,000 to 400,000 g/mol;
• (ii) 80 wt. % to 99 wt. % of an API group II, III, or IV base oil, or a mixture thereof;
• and
• (iii) 0 wt. % to 2.5 wt. % of a zinc-free performance package comprising at least an antiwear agent, an anticorrosion agent, and an antioxidant,
• wherein the compressor oil has a kinematic viscosity at 40° C. in the range of 28.8 and 74.8 cSt and a viscosity index of at least 140.

15:

• The method according to claim 1, wherein the compressor is a carbon dioxide compressor, the method comprising:
• operating the carbon dioxide compressor with the compressor oil, wherein the compressor oil comprises:
• (i) 1 wt. % to 20 wt. % of the polyalkyl methacrylate-based viscosity index improver comprising:
• (a) 0.2 wt. % to 25 wt. % of the methyl methacrylate;
• and
• (b) 75 wt. % to 99.8 wt. % of the at least one C10-18 alkyl (meth)acrylate,
• wherein the weight average molecular weight (Mw) of the polyalkyl (meth)acrylate-based viscosity index improver is in the g range of 5,000 g/mol to 100,000 g/mol;
• (ii) 80 wt. % to 95 wt. % of a polyolester base oil or g mixture of different polyester base oils;
• and
• (iii) 0 wt. % to 2.5 wt. % of a zinc-free performance package comprising at least an antiwear agent, an anticorrosion agent, and an antioxidant,
• wherein the compressor oil has a kinematic viscosity at 40° C. in the range of 41.4 and 110 cSt, and a viscosity index of at least 140.

16:

• The method according to claim 1, wherein the compressor is a carbon dioxide compressor, the method comprising:
• operating the carbon dioxide compressor with the compressor oil, wherein the compressor oil comprises:
• (i) 1 wt. % to 30 wt. % the polyalkyl methacrylate-based viscosity index improver comprising:
• (a) 0.2 wt. % to 25 wt. % of the methyl methacrylate;
• and
• (b) 75 wt. % to 99.8 wt. % of the at least one C10-18 alkyl (meth)acrylate,
• wherein the weight average molecular weight (Mw) of the polyalkyl (meth)acrylate-based viscosity index improver is in a range of 5,000 g/ml to 100,000 g/mol;
• (ii) 80 wt. % to 99 wt. % of a polyalphaolefin base oil or mixture of different polyalphaolefin base oils;
• and
• (iii) 0 wt. % to 2.5 wt. % of a zinc-free performance package comprising at least an antiwear agent, an anticorrosion agent, and an antioxidant,
• wherein the compressor oil has a kinematic viscosity at 40° C. in the range of 41.4 and 110 cSt and a viscosity index of at least 140.

18:

• The method according to claim 2, wherein the polyalkyl methacrylate-based viscosity index improver comprises:
• (a) 4 wt. % to 16 wt. % of the methyl methacrylate;
• (b) 84 wt. % to 96 wt. % of the at least one C10-18 alkyl methacrylate;
• and
• (c) 0 wt. % to 2 wt. % of the at least one straight-chained or branched C5-9 alkyl (meth)acrylate or the at least one straight-chained or branched C20-24 alkyl (meth)acrylate.