Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
  • C10M171/008—Lubricant compositions compatible with refrigerants
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
  • C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
  • C10M105/32—Esters
  • C10M105/38—Esters of polyhydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/28—Esters
  • C10M2207/283—Esters of polyhydroxy compounds
  • C10M2207/2835—Esters of polyhydroxy compounds used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/01—Physico-chemical properties
  • C10N2020/02—Viscosity; Viscosity index
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
  • C10N2020/09—Characteristics associated with water
  • C10N2020/097—Refrigerants
  • C10N2020/101—Containing Hydrofluorocarbons
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/02—Pour-point; Viscosity index
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/30—Refrigerators lubricants or compressors lubricants

Definitions

• the present invention relates to a base oil for refrigerating machine oil, a refrigerating machine oil, and a working fluid composition.
• Refrigerating machines such as refrigerators, car air conditioners, room air conditioners, and vending machines are equipped with compressors for circulating a refrigerant within a refrigeration cycle.
• the compressor is filled with a refrigerating machine oil for lubricating sliding members.
• the refrigerating machine oil contains a base oil as a main component.
• a suitable base oil is selected according to required properties.
• Patent Literature 1 discloses a refrigerating machine oil containing an ester of dipentaerythritol and a fatty acid, wherein the proportion of 2-methylpentanoic acid in the fatty acid is 20 mol% or more.
• Patent Literature 1 Japanese Unexamined Patent Publication No. 2015-206059
• one aspect of the present invention aims to provide a base oil for refrigerating machine oil, a refrigerating machine oil, and a working fluid composition that can suppress the refrigerant dissolution viscosity at low temperature side while maintaining the kinematic viscosity at high temperature side.
• a mixed base oil obtained by mixing at least one selected from a diester of neopentyl glycol and a tetraester of pentaerythritol and a specific fatty acid with a hexaester can suppress the refrigerant dissolution viscosity at low temperature side while maintaining the kinematic viscosity at high temperature side.
• the present invention includes the following aspects.
• a base oil for refrigerating machine oil a refrigerating machine oil, and a working fluid composition that can maintain kinematic viscosity on the high temperature side while suppressing refrigerant dissolution viscosity on the low temperature side to a low level.
• One embodiment of the present invention is a base oil for refrigerating machine oil comprising: a hexaester of dipentaerythritol and a fatty acid (hereinafter also referred to as “ester (A)”); and at least one ester selected from the group consisting of a diester of neopentyl glycol and a fatty acid (hereinafter also referred to as “ester (B-1)”), and a tetraester of pentaerythritol and a fatty acid containing a fatty acid having 4 to 6 carbon atoms (hereinafter also referred to as “ester (B-2)”) (hereinafter also referred to as "ester (B)").
• the fatty acid constituting ester (A) is preferably a saturated fatty acid, and more preferably a saturated fatty acid having 4 to 9, 5 to 9, 6 to 9, 7 to 9, or 8 to 9 carbon atoms.
• the fatty acid may be linear or branched.
• the fatty acid preferably includes a fatty acid having a branch at the ⁇ -position and/or ⁇ -position.
• the fatty acid more preferably includes at least one selected from the group consisting of 2-methylpropanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, neopentanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid, and from the viewpoint of more easily maintaining higher kinematic viscosity at 100°C, further preferably includes at least one selected from the group consisting of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid.
• the fatty acid may be a mixed fatty acid of branched fatty acids.
• Examples of such mixed fatty acids include a mixed fatty acid of 2-methylpropanoic acid and 2-ethylhexanoic acid or 3,5,5-trimethylhexanoic acid, a mixed fatty acid of 2-methylbutanoic acid and 2-ethylhexanoic acid or 3,5,5-trimethylhexanoic acid, a mixed fatty acid of 2-methylpentanoic acid and 2-ethylhexanoic acid or 3,5,5-trimethylhexanoic acid, and a mixed fatty acid of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid.
• the fatty acid may be a linear fatty acid, or may be a mixed fatty acid of linear fatty acids and branched fatty acids.
• linear fatty acids include n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, and n-nonanoic acid.
• Examples of mixed fatty acids of linear fatty acids and branched fatty acids include a mixed fatty acid of n-pentanoic acid and 2-methylbutanoic acid, a mixed fatty acid of n-pentanoic acid and 3,5,5-trimethylhexanoic acid, a mixed fatty acid of n-heptanoic acid and 3,5,5-trimethylhexanoic acid, and a mixed fatty acid of n-pentanoic acid, n-heptanoic acid, and 3,5,5-trimethylhexanoic acid.
• the fatty acid constituting ester (B-1) is preferably a saturated fatty acid, and more preferably a saturated fatty acid having 4 to 9, 5 to 9, 6 to 9, 7 to 9, or 8 to 9 carbon atoms.
• the fatty acid may be linear or branched.
• the fatty acid is preferably branched, more preferably selected from 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid, and further preferably 3,5,5-trimethylhexanoic acid.
• the fatty acid constituting ester (B-2) contains a fatty acid having 4 to 6 carbon atoms (hereinafter also referred to as "C4-C6 acid").
• the C4-C6 acid is preferably a saturated fatty acid, and more preferably a saturated fatty acid having 4 to 5 or 4 carbon atoms.
• the C4-C6 acid may be linear or branched.
• the C4-C6 acid may be at least one selected from the group consisting of linear or branched butanoic acid, linear or branched pentanoic acid, and linear or branched hexanoic acid, preferably includes at least one selected from the group consisting of branched butanoic acid, branched pentanoic acid, and branched hexanoic acid, more preferably includes at least one selected from the group consisting of 2-methylpropanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, neopentanoic acid, and 2-methylpentanoic acid, includes at least one selected from the group consisting of 2-methylpropanoic acid and 2-methylbutanoic acid, and further preferably includes 2-methylpropanoic acid.
• the fatty acid constituting ester (B-2) may further contain other fatty acids in addition to the C4-C6 acid.
• the other fatty acids are preferably fatty acids having 7 to 9 carbon atoms (hereinafter also referred to as "C7-C9 acid").
• the C7-C9 acid is preferably a saturated fatty acid, and more preferably a saturated fatty acid having 8 to 9 carbon atoms.
• the C7-C9 acid may be linear or branched.
• the C7-C9 acid is preferably branched, more preferably selected from 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid, and further preferably 3,5,5-trimethylhexanoic acid.
• the fatty acid constituting ester (B-2) may be a mixed fatty acid of linear fatty acids and branched fatty acids.
• Examples of such mixed fatty acids include a mixed fatty acid of one or more selected from n-pentanoic acid and n-heptanoic acid, and 3,5,5-trimethylhexanoic acid.
• the molar ratio of C4-C6 acid to C7-C9 acid (C4-C6 acid/C7-C9 acid) in the fatty acid constituting ester (B-2) may be 10/90 or more, 20/80 or more, or 30/70 or more, and may be 90/10 or less, 80/20 or less, 70/30 or less, 60/40 or less, or 50/50 or less.
• Ester (A) may include an ester having 40 or more or 50 or more carbon atoms, and from the viewpoint of easily maintaining high kinematic viscosity at 100°C, preferably includes an ester having 54 or more or 60 or more, and 64 or less carbon atoms.
• ester (A) has 34 to 64 carbon atoms.
• Ester (B) may include an ester having 38 or less or 35 or less carbon atoms, and from the viewpoint of increasing the amount of refrigerant dissolved at low temperatures and easily reducing refrigerant dissolution viscosity at low temperatures, preferably includes an ester having 31 or less or 25 or less, and 18 or more or 20 or more carbon atoms.
• ester (B-1) has 13 to 23 carbon atoms.
• ester (B-2) has 21 to 41 carbon atoms.
• the difference between the maximum value of the number of carbon atoms of the ester (maximum carbon number) and the minimum value of the number of carbon atoms of the ester (minimum carbon number) in the mixture of ester (A) and ester (B) is preferably 28 or more, 35 or more, 37 or more, or 41 or more, and preferably 46 or less or 44 or less.
• the average carbon number of ester (A) may be 40 or more or 50 or more, is preferably 54 or more or 60 or more, and may be 64 or less.
• the average carbon number of ester (B) may be 38 or less or 35 or less, is preferably 31 or less or 25 or less, and may preferably be 18 or more or 20 or more.
• the average carbon number of the mixture of ester (A) and ester (B) contained in the base oil is preferably 35 or more, 38 or more, or 40 or more, and preferably 58 or less, 55 or less, 52 or less, 48 or less, or 45 or less.
• the value obtained by dividing the difference between the maximum carbon number and the minimum carbon number in the mixture of ester (A) and ester (B) by the average carbon number is preferably 0.70 or more, 0.80 or more, 0.85 or more, or 0.90 or more, and preferably 1.50 or less, 1.20 or less, 1.00 or less, or 0.97 or less.
• This value indicates the degree of dispersion of the molecular weight of the ester, and even with the same average carbon number, it becomes 0 for a single molecule and becomes a larger value as the maximum and minimum values of the molecular weight of the ester become larger. From the viewpoint of the balance with refrigerant compatibility, flash point, 100°C kinematic viscosity, and the effect of reducing refrigerant dissolution viscosity, the above range is preferable.
• the ratio (Mw/Mn) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) in the mixture of ester (A) and ester (B) may be 1.01 or more, 1.05 or more, or 1.10 or more, and may be 1.5 or less, 1.4 or less, or 1.3 or less.
• Mw and Mn in this specification mean values obtained by GPC analysis (polystyrene-equivalent values (standard sample)).
• a solution is prepared by using tetrahydrofuran as a solvent and diluting to a sample concentration of 1% by mass, and analysis is performed using a GPC apparatus (for example, ACQUITY APC UV RI system manufactured by Waters Corporation) with the solvent flow rate set to 0.7 ml/min, the temperature set to 40°C, using a column with an analyzable molecular weight of 100 to 10000, and using a refractive index detector.
• the relationship between column retention time and molecular weight is determined using polystyrene standards with known molecular weights, a calibration curve is separately prepared, and the molecular weight is determined from the obtained retention time.
• the content of ester (A) and ester (B) (and further ester (B-1) and ester (B-2)) in the base oil is appropriately adjusted according to the desired kinematic viscosity of the base oil and other factors.
• the content of ester (A) in the base oil may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the total amount of the base oil.
• the content of ester (B-1) in the base oil may be 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 20% by mass or more, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less, based on the total amount of the base oil.
• the content of ester (B-2) in the base oil may be 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, or 70% by mass or less, based on the total amount of the base oil.
• Ester (B) may contain either one of ester (B-1) and ester (B-2), or may contain both ester (B-1) and ester (B-2).
• ester (B) preferably contains both ester (B-1) and ester (B-2). That is, from the viewpoint of further suppressing refrigerant dissolution viscosity to a low level, the base oil preferably contains ester (A), ester (B-1), and ester (B-2).
• the content of ester (B-1) may be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, or 9% by mass or more, and may be 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total amount of the base oil.
• ester (B-2) may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the total amount of the base oil.
• the proportion of dipentaerythritol in the total amount of alcohols constituting ester (A) and ester (B) in the base oil may be 5 mol% or more, 10 mol% or more, 15 mol% or more, or 20 mol% or more, and may be 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, or 30 mol% or less.
• the proportion of neopentyl glycol in the total amount of alcohols constituting ester (A) and ester (B) in the base oil may be 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, 30 mol% or less, or 20 mol% or less, may be 0 mol%, and may be 5 mol% or more, or 10 mol% or more.
• the proportion of pentaerythritol in the total amount of alcohols constituting ester (A) and ester (B) in the base oil may be 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, or 30 mol% or less, may be 0 mol%, and may be 5 mol% or more, 10 mol% or more, 15 mol% or more, or 20 mol% or more.
• the proportion of C7-C9 acid in the total amount of fatty acids constituting ester (A) and ester (B) in the base oil may be 40 mol% or more, 50 mol% or more, 60 mol% or more, or 70 mol% or more, may be 100 mol%, and may be 90 mol% or less, 85 mol% or less, or 80 mol% or less.
• the proportion of fatty acids having 8 to 9 carbon atoms (C8-C9 acid) in the total amount of fatty acids constituting ester (A) and ester (B) in the base oil may be in the above range.
• the proportion of C4-C6 acid in the fatty acids constituting ester (A) and ester (B) in the base oil may be 50 mol% or less, 35 mol% or less, 30 mol% or less, or 26 mol% or less, and may be 5 mol% or more, 10 mol% or more, 15 mol% or more, or 20 mol% or more.
• the proportion of fatty acids having 4 carbon atoms (C4 acid), the proportion of fatty acids having 5 carbon atoms (C5 acid), or the proportion of the total of C4 acid and C5 acid in the total amount of fatty acids constituting ester (A) and ester (B) in the base oil may each be in the above range.
• the ratio of C4-C6 acid to C7-C9 acid (molar ratio of C4-C6 acid/C7-C9 acid) in the fatty acids constituting ester (A) and ester (B) in the base oil may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less, may be 0, and may be 0.1 or more, 0.15 or more, or 0.2 or more.
• the ratio of C4 acid to C8-C9 acid (molar ratio of C4 acid/C8-C9 fatty acid) in the fatty acids constituting ester (A) and ester (B) in the base oil may be 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less, may be 0, and may be 0.1 or more, 0.15 or more, or 0.2 or more.
• the ratio of C5 acid to C8-C9 acid (molar ratio of C5 acid/C8-C9 fatty acid) or the ratio of the total of C4 acid and C5 acid to C8-C9 acid (molar ratio of C4 acid and C5 acid/C8-C9 fatty acid) in the fatty acids constituting ester (A) and ester (B) in the base oil may be in the above range.
• the average carbon number of the fatty acids constituting ester (A) and ester (B) in the base oil may be 5 or more, 6 or more, 6.5 or more, 7 or more, or 7.5 or more, and may be 9.0 or less, 8.4 or less, 8.2 or less, or 8.0 or less.
• the kinematic viscosity of ester (A) at 40°C may be 40 mm 2 /s or more, 100 mm 2 /s or more, 150 mm 2 /s or more, or 200 mm 2 /s or more, and may be 500 mm 2 /s or less, 400 mm 2 /s or less, 300 mm 2 /s or less, or 250 mm 2 /s or less.
• the kinematic viscosity of ester (B) at 40°C may be 3 mm 2 /s or more, 5 mm 2 /s or more, 10 mm 2 /s or more, or 20 mm 2 /s or more, and may be 100 mm 2 /s or less, 90 mm 2 /s or less, 80 mm 2 /s or less, or 70 mm 2 /s or less.
• the kinematic viscosity of ester (B-1) at 40°C may be 3 mm 2 /s or more, 5 mm 2 /s or more, or 10 mm 2 /s or more, and may be 50 mm 2 /s or less, 30 mm 2 /s or less, 20 mm 2 /s or less, or 15 mm 2 /s or less.
• the kinematic viscosity of ester (B-2) at 40°C may be 20 mm 2 /s or more, 30 mm 2 /s or more, 40 mm 2 /s or more, or 50 mm 2 /s or more, and may be 100 mm 2 /s or less, 90 mm 2 /s or less, 80 mm 2 /s or less, or 70 mm 2 /s or less.
• the kinematic viscosity of the base oil at 40°C may be 10 mm 2 /s or more, 20 mm 2 /s or more, 30 mm 2 /s or more, 40 mm 2 /s or more, 50 mm 2 /s or more, 60 mm 2 /s or more, or 70 mm 2 /s or more, and may be 500 mm 2 /s or less, 400 mm 2 /s or less, 300 mm 2 /s or less, 200 mm 2 /s or less, 150 mm 2 /s or less, 100 mm 2 /s or less, 90 mm 2 /s or less, or 80 mm 2 /s or less.
• the kinematic viscosity of ester (A) at 100°C may be 5 mm 2 /s or more, 10 mm 2 /s or more, 15 mm 2 /s or more, or 20 mm 2 /s or more, and may be 50 mm 2 /s or less, 40 mm 2 /s or less, 30 mm 2 /s or less, or 20 mm 2 /s or less.
• the kinematic viscosity of ester (B-1) at 100°C may be 1 mm 2 /s or more, 1.5 mm 2 /s or more, 2 mm 2 /s or more, or 2.5 mm 2 /s or more, and may be 5 mm 2 /s or less, 4 mm 2 /s or less, or 3.5 mm 2 /s or less.
• the kinematic viscosity of ester (B-2) at 100°C may be 3 mm 2 /s or more, 5 mm 2 /s or more, 6 mm 2 /s or more, or 8 mm 2 /s or more, and may be 20 mm 2 /s or less, 15 mm 2 /s or less, 10 mm 2 /s or less, or 8.5 mm 2 /s or less.
• the viscosity index of ester (A), ester (B), ester (B-1), and ester (B-2) may each be 50 or more, 60 or more, 70 or more, or 80 or more, and may be 150 or less, 130 or less, 120 or less, or 100 or less.
• kinematic viscosity and viscosity index in this specification mean the kinematic viscosity and viscosity index measured in accordance with JIS K 2283:2000, respectively.
• the base oil for refrigerating machine oil described above can maintain kinematic viscosity on the high temperature side while suppressing refrigerant dissolution viscosity on the low temperature side to a low level.
• the base oil for refrigerating machine oil may also have excellent refrigerant compatibility.
• the base oil for refrigerating machine oil can also suppress kinematic viscosity on the low temperature side to a low level.
• the content of ester (A) in the refrigerating machine oil may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the total amount of the refrigerating machine oil.
• the content of ester (B) in the refrigerating machine oil may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the total amount of the refrigerating machine oil.
• the content of ester (B-1) in the refrigerating machine oil may be 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 20% by mass or more, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less, based on the total amount of the refrigerating machine oil.
• the content of ester (B-2) in the refrigerating machine oil may be 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, or 70% by mass or less, based on the total amount of the refrigerating machine oil.
• ester (B-1) when the refrigerating machine oil contains both ester (B-1) and ester (B-2), the content of ester (B-1) may be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, or 9% by mass or more, and may be 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, or 15% by mass or less, based on the total amount of the refrigerating machine oil.
• ester (B-2) may be 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or less, based on the total amount of the refrigerating machine oil.
• the base oil constituting the refrigerating machine oil may contain only the above-described base oil for refrigerating machine oil, or may further contain other base oils in addition to the above-described base oil for refrigerating machine oil.
• the other base oils may be hydrocarbon oils, and may be mineral oils or synthetic hydrocarbon oils.
• mineral oils include paraffinic or naphthenic mineral oils refined by appropriately combining ordinary petroleum refining processes (solvent deasphaltening, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, distillation, etc.) using crude oil or its distillation residue oil as a raw material.
• Examples of synthetic hydrocarbon oils include poly- ⁇ -olefins or their hydrides, normal paraffins, isoparaffins, alkylbenzenes, alkylnaphthalenes, and the like.
• the other base oils may be oxygen-containing oils other than ester (A) and ester (B).
• oxygen-containing oils include esters other than ester (A) and ester (B), ethers, carbonates, ketones, silicones, polysiloxanes, and the like.
• esters include monoesters, polyol esters other than ester (A) and ester (B), aromatic esters, dibasic acid esters, complex esters, and carbonate esters.
• ethers include polyvinyl ethers, polyalkylene glycols, polyphenyl ethers, and perfluoroethers.
• the refrigerating machine oil may further contain additives.
• additives include antiwear agents, antioxidants, acid scavengers, oxygen scavengers, metal deactivators, pour point depressants, detergent/dispersants, defoamers, and the like.
• the total content of additives may be 10% by mass or less or 5% by mass or less, based on the total amount of the refrigerating machine oil.
• the kinematic viscosity of the refrigerating machine oil at 40°C may be 10 mm 2 /s or more, 20 mm 2 /s or more, 30 mm 2 /s or more, 40 mm 2 /s or more, 50 mm 2 /s or more, 60 mm 2 /s or more, 70 mm 2 /s or more, or 75 mm 2 /s or more, and may be 500 mm 2 /s or less, 400 mm 2 /s or less, 300 mm 2 /s or less, 200 mm 2 /s or less, 150 mm 2 /s or less, 100 mm 2 /s or less, 90 mm 2 /s or less, or 87 mm 2 /s or less.
• the kinematic viscosity of the refrigerating machine oil at 100°C may be 5 mm 2 /s or more, 6 mm 2 /s or more, 7 mm 2 /s or more, 8 mm 2 /s or more, 8.5 mm 2 /s or more, 9 mm 2 /s or more, or 9.5 mm 2 /s or more, and may be 50 mm 2 /s or less, 30 mm 2 /s or less, 20 mm 2 /s or less, 15 mm 2 /s or less, 13 mm 2 /s or less, 12 mm 2 /s or less, or 11 mm 2 /s or less.
• the kinematic viscosity of the refrigerating machine oil at -20°C may be 5000 mm 2 /s or more, 10000 mm 2 /s or more, 12000 mm 2 /s or more, 14000 mm 2 /s or more, or 20000 mm 2 /s or more, and may be 50000 mm 2 /s or less, 45000 mm 2 /s or less, 40000 mm 2 /s or less, 35000 mm 2 /s or less, or 30000 mm 2 /s or less.
• the viscosity index of the refrigerating machine oil may be 70 or more, 80 or more, or 90 or more, and may be 150 or less, 130 or less, or 110 or less.
• the refrigerating machine oil can exist in a refrigerating machine in the state of a working fluid composition mixed with a refrigerant. That is, another embodiment of the present invention is a working fluid composition comprising the above refrigerating machine oil and a refrigerant.
• the content of the refrigerating machine oil in the working fluid composition may be 1 part by mass or more or 2 parts by mass or more, and may be 500 parts by mass or less or 400 parts by mass or less, relative to 100 parts by mass of the refrigerant.
• the refrigerant examples include saturated fluorocarbon (also called HFC), unsaturated fluorocarbon (also called HFO), hydrocarbon, fluorinated ether, bis(trifluoromethyl) sulfide, trifluoroiodomethane, ammonia, and carbon dioxide.
• saturated fluorocarbon also called HFC
• unsaturated fluorocarbon also called HFO
• hydrocarbon fluorinated ether
• fluorinated ether also called bis(trifluoromethyl) sulfide
• trifluoroiodomethane ammonia
• carbon dioxide examples include carbon dioxide.
• the refrigerant may be a single refrigerant of one of these refrigerants, or may be a mixed refrigerant of two or more.
• the refrigerant preferably includes at least one selected from the group consisting of unsaturated fluorocarbon and hydrocarbon, and more preferably includes at least one selected from the group consisting of unsaturated fluorocarbon.
• unsaturated fluorocarbon examples include unsaturated fluorocarbon having 2 to 4 carbon atoms that has one or more carbon-carbon double bonds and has fluorine and hydrogen.
• the unsaturated fluorocarbon is preferably fluoropropene, and more preferably fluoropropene having 3 to 5 fluorine atoms.
• unsaturated fluorocarbon examples include 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-1234ye), and 3,3,3-trifluoropropene (HFO-1243zf).
• the unsaturated fluorocarbon is preferably at least one selected from HFO-1225ye, HFO-1234ze, and HFO-1234yf.
• the unsaturated fluorocarbon may be fluoroethylene, preferably fluoroethylene having 1 to 3 fluorine atoms, and more specifically, may be at least one selected from, for example, monofluoroethylene (HFO-1141), 1,1-difluoroethylene (HFO-1132a), (E)-1,2-difluoroethylene (HFO-1132(E)), (Z)-1,2-difluoroethylene (HFO-1132(Z)), and 1,1,2-trifluoroethylene (R1123).
• monofluoroethylene HFO-1141
• 1,1-difluoroethylene HFO-1132a
• E -1,2-difluoroethylene
• Z 1,1,2-trifluoroethylene
• the unsaturated fluorocarbon may be an unsaturated fluorocarbon having chlorine atoms and fluorine atoms, and specifically, may be at least one selected from, for example, 1-chloro-2,2-difluoroethylene (HCFO-1122), (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)), and (E)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(E)).
• HCFO-1122 1-chloro-2,2-difluoroethylene
• Z Z-1-chloro-2,3,3,3-tetrafluoropropene
• E E-1-chloro-2,3,3,3-tetrafluoropropene
• the refrigerant may be a mixed refrigerant containing the above unsaturated fluorocarbon having 2 to 4 carbon atoms.
• mixed refrigerants include R444A, R444B, R445A, R446A, R447A, R447B, R448A, R448B, R449A, R449B, R449C, R450A, R451A, R451B, R452A, R452B, R452C, R454A, R454B, R454C, R455A, R455C, R455D, R456A, R457A, R457B, R457C, R457D, R459A, R459B, R460A, R460B, R460C, R463A, R464A, R465A, R468A, R468B, R468C, R470A, R470B, R471A, R473A, R47
• the hydrocarbon is preferably a hydrocarbon having 1 to 5 carbon atoms, and more preferably a hydrocarbon having 2 to 4 carbon atoms.
• hydrocarbons include methane, ethylene, ethane, propylene (R1270), propane (R290), cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, 2-methylbutane, and normal pentane.
• the hydrocarbon is preferably a single refrigerant or a mixed refrigerant of two or more selected from the group consisting of propane, propylene, normal butane, isobutane, and 2-methylbutane.
• Tetraester of pentaerythritol (PE) and fatty acid mixed fatty acid of 37 mol% 2-methylpropanoic acid (iC4 acid) and 63 mol% 3,5,5-trimethylhexanoic acid (iC9 acid)) (average carbon number: 34, minimum carbon number: 21, kinematic viscosity at 100°C: 8.2 mm 2 /s, viscosity index: 84)
• kinematic viscosity and viscosity index at -20°C, 40°C, and 100°C were measured in accordance with JIS K 2283:2000.
• the following measurements were performed using each of the obtained base oils (refrigerating machine oils). The measurement results are shown in Tables 1 and 2.
• Tables 1 and 2 show the proportions (mol%) of DiPE, NPG, and PE in the total amount of alcohols constituting the esters as “DiPE proportion (mol%)", “NPG proportion (mol%)", and “PE proportion (mol%)", respectively.
• Tables 1 and 2 also show the proportions (mol%) of iC9 acid, iC8 acid, C7-C9 acid, and C4-C6 acid in the total amount of fatty acids constituting the esters as “iC9 acid proportion (mol%)", “iC8 acid proportion (mol%)”, “C7-C9 acid proportion (mol%)", and “C4-C6 acid proportion (mol%)", respectively, and the ratio (molar ratio) of C4-C6 acid to C7-C9 acid is shown as "C4-C6 acid/C7-C9 acid molar ratio”.
• Each refrigerating machine oil was filled into a pressure-resistant vessel equipped with a vibrational viscometer, thermometer, and pressure gauge. After vacuum degassing the inside of the pressure-resistant vessel, refrigerant (HFO-1234yf) was filled so that the refrigerant ratio was approximately 13.6%, and a working fluid composition consisting of the refrigerating machine oil and refrigerant was prepared (approximately half the capacity of the pressure-resistant vessel).
• refrigerant HFO-1234yf
• the absolute viscosity P (mPa ⁇ s) of the working fluid composition was measured using a vibrational viscometer, and the refrigerant dissolution viscosity (mm 2 /s) was calculated from the measurement results of the density (g/cm 3 ) of the working fluid composition.
• the refrigerant dissolution viscosity R-Vis (mm 2 /s) was determined as P/Dw, where the absolute viscosity P (mPa ⁇ s) was divided by the density Dw (g/cm 3 ) of the working fluid composition.
• Example 1 Example 2 Example 3 Example 4 Base Oil Composition (mass%) Ester (A) DiPE/ iC8:50%+iC9:50% 46 25 80 72 Ester (B-1) NPG/iC8 - - 20 - NPG/iC9 - - - 28 Ester (B-2) PE/ iC4:60%+iC9:40% 54 - - - PE/ iC4:37%+iC9:63% - 75 - - Ester (C) PE/ iC8:48%+iC9:52% - - - DiPE Ratio (mol%) 28.9 15.0 56.8 46.7 NPG Ratio (mol%) 0.0 0.0 43.2 53.3 PE Ratio (mol%) 71.1 85.0 0.0 0.0 iC9 Acid Ratio (mol%) 42.9 61.0 28.4 76.6 iC8 Acid Ratio (mol%) 14.4 7.5 71.6 23.4 C7-C9 Acid Ratio (B-1)

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