Refrigerator oil and working fluid composition for refrigerator

Abstract

A refrigerating machine oil comprising 90% of a hydrocarbon base oil having a distillation temperature of 270°C or less.

Description

Technical Field

[0001] The present invention relates to refrigeration oil and a working fluid composition for refrigeration machines. Background Art

[0002] In refrigerators, it is becoming increasingly urgent to replace refrigerants having a high global warming potential (GWP) with low GWP refrigerants, for example, less than 150. Examples of low GWP refrigerants include carbon dioxide (R744) refrigerants and hydrocarbon refrigerants.

[0003] On the other hand, energy conservation is also required for refrigerators. Generally, the lower the viscosity of refrigerator oil, the less stirring resistance and friction of sliding parts can be reduced. Therefore, the low viscosity of refrigerator oil is related to the energy conservation of refrigerators. For example, Patent Document 1 discloses refrigerator oil with a VG3 or higher and a VG8 or lower. In addition, for example, Patent Document 2 discloses refrigerator oil containing a mixed base oil composed of a low-viscosity base oil and a high-viscosity base oil.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2006 / 062245

[0007] Patent Document 2: International Publication No. 2007 / 105452 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, if the viscosity of the refrigeration oil decreases, it becomes difficult to maintain the oil film in the sliding part, so there is a concern that the friction coefficient may increase. Therefore, an object of one aspect of the present invention is to provide a refrigeration oil with low viscosity and a reduced friction coefficient.

[0010] Solutions for solving problems

[0011] One aspect of the present invention is a refrigerating machine oil comprising: a hydrocarbon base oil having a distillation temperature of 270° C. or lower in a 90% ratio.

[0012] The initial distillation point of the hydrocarbon base oil may be above 140°C. The refrigeration oil may further contain a phosphorus-containing antiwear agent. The flash point of the refrigeration oil may be above 70°C. The content of hydrocarbons with a carbon number of 12 to 16 in the hydrocarbon base oil contained in the refrigeration oil may be above 80% by mass. The difference between the 90% distillation temperature and the 10% distillation temperature of the refrigeration oil may be above 5°C and below 40°C. The residual carbon component of the 10% residual oil of the refrigeration oil may be above 0.02% by mass. The content of normal paraffins in the hydrocarbon base oil contained in the refrigeration oil may be above 5% by mass and below 50% by mass. The 90% distillation temperature of the refrigeration oil may be below 270°C.

[0013] Another aspect of the present invention may be a working fluid composition for a refrigerator, comprising: the refrigerator oil and a refrigerant. The refrigerant may contain a hydrocarbon.

[0014] Effects of the Invention

[0015] According to one aspect of the present invention, a refrigerating machine oil having a low viscosity and a low friction coefficient can be provided. DETAILED DESCRIPTION

[0016] Hereinafter, an embodiment of the present invention will be described in detail. One embodiment of the present invention is a refrigeration oil, which contains: a hydrocarbon base oil having a 90% distillation temperature of 270°C or less. In the refrigeration oil, by using a hydrocarbon base oil having a specified 90% distillation temperature, the viscosity is low and the friction coefficient can be reduced. The 90% distillation temperature is measured according to the normal pressure method described in JIS K2254:2018. Hereinafter, the distillation properties of the hydrocarbon base oil and the refrigeration oil are measured in the same manner according to this method.

[0017] The 90% distillation temperature (T90) of the hydrocarbon base oil may be preferably 267°C or lower, 266°C or lower, 265°C or lower, 264°C or lower, 263°C or lower, 262°C or lower, or 261°C or lower, from the viewpoint of further reducing the friction coefficient, and may be, for example, 220°C or higher, 230°C or higher, 240°C or higher, 245°C or higher, or 250°C or higher.

[0018] The initial boiling point (IBP) of the hydrocarbon base oil may preferably be 140°C or higher, 170°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, or 240°C or higher, from the viewpoint of further reducing the friction coefficient, and may be 260°C or lower, 255°C or lower, or 250°C or lower.

[0019] The 10% distillation temperature (T10) of the hydrocarbon base oil may preferably be 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, or 240°C or higher, and may be 260°C or lower, 255°C or lower, or 250°C or lower, from the viewpoint of further reducing the friction coefficient.

[0020] The 50% distillation temperature (T50) of the hydrocarbon base oil may preferably be 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, or 245°C or higher, and may be 265°C or lower, 260°C or lower, 255°C or lower, or 250°C or lower, from the viewpoint of further reducing the friction coefficient.

[0021] The end distillation point (EP) of the hydrocarbon base oil may preferably be 250°C or higher, 260°C or higher, 270°C or higher, 275°C or higher, or 280°C or higher, and may be 320°C or lower, 310°C or lower, 300°C or lower, 295°C or lower, or 290°C or lower, from the viewpoint of further reducing the friction coefficient.

[0022] The difference between T90 and T10 (T90-T10) of the hydrocarbon base oil may preferably be 5°C or more, 6°C or more, 7°C or more, 8°C or more, 9°C or more, or 10°C or more, and may be 40°C or less, 30°C or less, 20°C or less, or 15°C or less, from the viewpoint of further reducing the friction coefficient.

[0023] The total distillate amount of the hydrocarbon base oil may be, for example, 95% by volume or more, 96% by volume or more, 97% by volume or more, 98% by volume or more, or 99% by volume or more, or 99.9% by volume or less. The residual oil content of the hydrocarbon base oil may be, for example, 0.1% by volume or more, or 6% by volume or less, 4% by volume or less, 3% by volume or less, 2% by volume or less, or 1% by volume or less. The loss amount of the hydrocarbon base oil may be, for example, 1% by volume or less, 0.5% by volume or less, or 0.1% by volume or less, or 0% by volume.

[0024] The kinematic viscosity of the hydrocarbon base oil at 40° C. may be, for example, 1.0 mm 2 / s or more, 1.5mm 2 / s or above, or 2.0mm 2 / s or more, can be 6.0mm 2 / s or less, 5.0mm 2 / s or less, 4.5mm 2 / s or less, 4.0mm 2 / s or less, 3.5mm 2 / s or less, or 3.0mm 2The kinematic viscosity in this specification means the kinematic viscosity measured according to JIS K2283:2000.

[0025] The kinematic viscosity of the hydrocarbon base oil at 100° C. may be, for example, 0.5 mm 2 / s or more, 0.7mm 2 / s or above, or 1.0mm 2 / s or more, can be 2.0mm 2 / s or less, 1.5mm 2 / s or less, 1.4mm 2 / s or less, 1.3mm 2 / s or less, 1.2mm 2 / s or less, or 1.1mm 2 / s or less.

[0026] The density of the hydrocarbon base oil may be, for example, 0.78 g / cm 3 Above, 0.79g / cm 3 Above, 0.80g / cm 3 Above, 0.81g / cm 3 Above, or 0.82g / cm 3 Above, it can be 0.84g / cm 3 Below, 0.83g / cm 3 Below, 0.82g / cm 3 Below, or 0.81g / cm 3 The density in this specification means the density at 15° C. measured according to the “vibration method” described in JIS K2249-1:2011.

[0027] The flash point of the hydrocarbon base oil may be, for example, 30°C or more, 60°C or more, 90°C or more, 100°C or more, or 110°C or more, or 150°C or less, 140°C or less, or 130°C or less. By increasing the initial boiling point of the hydrocarbon base oil, the flash point can be increased, and the safety can be further improved. The flash point in this specification refers to the flash point measured according to the Cleveland open (COC) method described in JIS K2265-4:2007.

[0028] The pour point of the hydrocarbon base oil may be, for example, -10°C or lower, -20°C or lower, -30°C or lower, or -40°C or lower, or may be -60°C or higher. The pour point in this specification means a pour point measured in accordance with JIS K2269:1987.

[0029] As hydrocarbon base oils having the above properties, for example, mineral oil hydrocarbon base oils, synthetic hydrocarbon base oils and their mixed base oils can be cited. As mineral oil hydrocarbon oils, there can be cited: using crude oil or its distillation residue as a raw material, appropriately combining conventional petroleum refining treatments (solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrofining, sulfuric acid cleaning, clay treatment, distillation, etc.) and refined paraffinic or cycloparaffinic refined mineral oils. As synthetic hydrocarbon oils, for example, polyalphaolefins or their hydrogenated products, isoparaffins, alkylbenzenes, alkylnaphthalenes, etc. can be cited. These hydrocarbon oils can be used alone or in combination of two or more.

[0030] From the viewpoint of easily obtaining the above-mentioned properties, the hydrocarbon base oil is preferably a mineral oil-based hydrocarbon base oil. More specifically, for example, the hydrocarbon base oil can be easily obtained by, for example, hydrotreating a lamp / light oil fraction obtained by atmospheric distillation of crude oil or a cracked light oil fraction obtained by cracking a residual oil feedstock containing atmospheric residue oil of crude oil or vacuum residue oil thereof, and fractionating the fraction so that the above-mentioned distillation properties, especially hydrocarbons having 12 to 16 carbon atoms or 13 to 18 carbon atoms, become the main component (e.g., 50% by mass or more, especially 80% by mass or more).

[0031] The refrigerating machine oil may contain only the hydrocarbon base oil having the above-mentioned properties (hereinafter also referred to as "hydrocarbon base oil A") as the base oil, or may contain other base oils as the base oil in addition to the hydrocarbon base oil A. The content of the hydrocarbon base oil A may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the base oil contained in the refrigerating machine oil. The content of the hydrocarbon base oil A may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the refrigerating machine oil.

[0032] The other base oil may be, for example, another hydrocarbon base oil (hereinafter also referred to as "hydrocarbon base oil B") other than the hydrocarbon base oil having the above-mentioned properties, an oxygen-containing base oil, etc., and is preferably hydrocarbon base oil B. The hydrocarbon base oil B may be, for example, a hydrocarbon base oil having a kinematic viscosity (e.g., a kinematic viscosity at 40° C., a kinematic viscosity at 100° C.) higher than that of the hydrocarbon base oil A.

[0033] The kinematic viscosity of the hydrocarbon base oil B at 40° C. may be, for example, 100 mm 2 / s or more, 200mm 2 / s or more, 300mm 2 / s or more, 400mm 2 / s or above, or 450mm 2 / s or more, can be 1000mm 2 / s or less, 800mm 2 / s or less, 600mm 2 / s or less, or 500mm 2 / s or less.

[0034] The kinematic viscosity of the hydrocarbon base oil B at 100° C. may be, for example, 10 mm 2 / s or more, 20mm 2 / s or above, or 30mm 2 / s or more, can be 100mm 2 / s or less, 50mm 2 / s or less, or 40mm 2 / s or less.

[0035] The viscosity index of the hydrocarbon base oil B may be, for example, 0 or more, 50 or more, or 80 or more, or 300 or less, 140 or less, or 100 or less. The viscosity index in this specification refers to a viscosity index measured in accordance with JIS K2283:2000.

[0036] The flash point of the hydrocarbon base oil B may be, for example, 200°C or higher, 250°C or higher, or 300°C or higher, and may be 500°C or lower, 450°C or lower, or 400°C or lower.

[0037] As the hydrocarbon base oil B, it is preferred to have the above-mentioned properties, but there is no particular limitation thereto. For example, a residual oil hydrocarbon base material in a crude oil refining process can be used. As the residual oil hydrocarbon base material, for example, there can be mentioned: a residual oil of atmospheric distillation of crude oil, a residual oil of vacuum distillation of the residual oil of atmospheric distillation, a deasphalted oil of these residual oils based on propane or the like, a solvent extraction extract oil of the aforementioned deasphalted oil based on furfural or the like, a solvent extraction residual oil liquid oil of the aforementioned deasphalted oil, a residual oil hydrocarbon base material obtained by subjecting these oils to a refining treatment such as hydrocracking, hydrofining, solvent dewaxing or hydrodewaxing, etc. Among these, a refined oil obtained by hydrofining a solvent extraction residual oil liquid of a deasphalted oil of a vacuum distillation residual oil, and subjecting it to solvent dewaxing or hydrodewaxing is particularly preferred.

[0038] The residual carbon content of the hydrocarbon base oil B is not particularly limited, but in terms of further improving the wear resistance, it is preferably 0.1 mass % or more, 0.2 mass % or more, 0.3 mass % or more, and preferably 10 mass % or less, 5 mass % or less, 1 mass % or less, or 0.8 mass % or less.

[0039] The ASTM chromaticity of the hydrocarbon base oil B may be 6.0 or less, 4.0 or less, or 3.0 or less, may be L0.5, or may be 0.5 or more, or 1.0 or more, from the viewpoint of the color tone of the refrigerating machine oil.

[0040] For the content of other base oils (preferably hydrocarbon base oil B), the total amount of base oil contained in the refrigerating machine oil can be 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 3% by mass or more, and can be 50% by mass or less, 30% by mass or less, 10% by mass or less, or 5% by mass or less. For the content of other base oils (preferably hydrocarbon base oil B), the total amount of refrigerating machine oil can be 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 3% by mass or more, and can be 50% by mass or less, 30% by mass or less, 10% by mass or less, or 5% by mass or less.

[0041] The refrigerator oil may also contain additives in addition to the above-mentioned base oil. As additives, anti-wear agents, antioxidants, acid capture agents, extreme pressure agents, metal deactivators, pour point depressants, clean dispersants, etc. may be cited. For the content of these additives, the refrigerator oil total amount may be 10% by mass or less or 5% by mass or less.

[0042] For refrigeration oil, from the viewpoint of improving wear resistance, it is preferred to contain an anti-wear agent as an additive. As an anti-wear agent, for example, a phosphorus-containing anti-wear agent can be cited. As a phosphorus-containing anti-wear agent, for example, phosphate esters, thiophosphate esters, acid phosphate esters, amine salts of acid phosphate esters, chlorinated phosphate esters, etc. can be cited. The anti-wear agent (preferably a phosphorus-containing anti-wear agent) can be used alone or in combination of two or more. The phosphorus-containing anti-wear agent is preferably selected from one or more of phosphate esters and thiophosphate esters.

[0043] Examples of the phosphoric acid ester include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, triethylphenyl phosphate, tributylphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, and cresyl diphenyl phosphate. The phosphoric acid ester is preferably triphenyl phosphate or tricresyl phosphate.

[0044] Examples of the phosphorothioate include tributyl phosphorothioate, tripentyl phosphorothioate, trihexyl phosphorothioate, triheptyl phosphorothioate, trioctyl phosphorothioate, trinonyl phosphorothioate, tridecyl phosphorothioate, triundecyl phosphorothioate, tridodecyl phosphorothioate, tritridecyl phosphorothioate, tritetradecyl phosphorothioate, tripentadecyl phosphorothioate, trihexadecyl phosphorothioate, triheptadecyl phosphorothioate, trioctadecyl phosphorothioate, trioleyl phosphorothioate, triphenyl phosphorothioate, tricresyl phosphorothioate, trixylyl phosphorothioate, cresyldiphenyl phosphorothioate, and xylyldiphenyl phosphorothioate. The phosphorothioate is preferably triphenyl phosphorothioate.

[0045] The content of the anti-wear agent (preferably a phosphorus-containing anti-wear agent) can be, for example, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, or 5% by mass or less, 4% by mass or less, or 3% by mass or less, based on the total amount of the refrigeration oil.

[0046] The initial boiling point (IBP) of the refrigeration oil may preferably be 140°C or higher, 170°C or higher, 190°C or higher, 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, or 240°C or higher, and may be 260°C or lower, 255°C or lower, or 250°C or lower, from the viewpoint of further reducing the friction coefficient.

[0047] The 10% distillation temperature (T10) of the refrigeration oil is preferably 200°C or higher, 210°C or higher, 220°C or higher, 230°C or higher, or 240°C or higher, and may be 260°C or lower, 255°C or lower, or 250°C or lower, from the viewpoint of further reducing the friction coefficient.

[0048] The 50% distillation temperature (T50) of the refrigeration oil is preferably 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, or 245°C or higher, and may be 265°C or lower, 260°C or lower, 255°C or lower, or 250°C or lower, from the viewpoint of further reducing the friction coefficient.

[0049] The 90% distillation temperature (T90) of the refrigeration oil is preferably 220°C or higher, 230°C or higher, 240°C or higher, 245°C or higher, or 250°C or higher, and may be 270°C or lower, 267°C or lower, 266°C or lower, 265°C or lower, 264°C or lower, 263°C or lower, 262°C or lower, or 261°C or lower, from the viewpoint of further reducing the friction coefficient.

[0050] The final boiling point (EP) of the refrigeration oil may preferably be 250°C or higher, 260°C or higher, 270°C or higher, 275°C or higher, or 280°C or higher, and may be 320°C or lower, 310°C or lower, 300°C or lower, 295°C or lower, or 290°C or lower, from the viewpoint of further reducing the friction coefficient.

[0051] The difference between T9 and T10 (T90-T10) of the refrigeration oil may preferably be 5°C or more, 6°C or more, 7°C or more, 8°C or more, 9°C or more, or 10°C or more, and may be 40°C or less, 30°C or less, 20°C or less, or 15°C or less, from the viewpoint of further reducing the friction coefficient.

[0052] The total distillate of the refrigeration oil can be, for example, 90% by volume or more, 93% by volume or more, or 95% by volume or more, or 99% by volume or less. The residual oil content of the refrigeration oil can be, for example, 1% by volume or more, or 10% by volume or less, 7% by volume or less, or 5% by volume or less. The loss of the refrigeration oil can be, for example, 1% by volume or less, 0.5% by volume or less, or 0.1% by volume or less, or 0% by volume.

[0053] The kinematic viscosity of the refrigeration oil at 40°C may be, for example, 1.0 mm 2 / s or more, 1.5mm 2 / s or above, or 2.0mm 2 / s or more, can be 6.0mm 2 / s or less, 5.0mm 2 / s or less, 4.5mm 2 / s or less, 4.0mm 2 / s or less, 3.5mm 2 / s or less, or 3.0mm 2 / s or less.

[0054] The kinematic viscosity of the refrigeration oil at 100°C may be, for example, 0.5 mm 2 / s or more, 0.7mm 2 / s or above, or 1.0mm 2 / s or more, can be 2.0mm 2 / s or less, 1.5mm 2 / s or less, 1.4mm 2 / s or less, 1.3mm 2 / s or less, 1.2mm 2 / s or less, or 1.1mm 2 / s or less.

[0055] The density of refrigeration oil can be, for example, 0.78 g / cm 3 Above, 0.79g / cm3 Above, or 0.80g / cm 3 Above, it can be 0.85g / cm 3 Below, 0.84g / cm 3 Below, or 0.83g / cm 3 the following.

[0056] The flash point of the refrigerating machine oil may be, for example, 70°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, or 110°C or higher, and may be 150°C or lower, 140°C or lower, or 130°C or lower.

[0057] The pour point of the refrigerating machine oil may be, for example, -10°C or lower, -20°C or lower, -30°C or lower, or -40°C or lower, and may be -60°C or higher.

[0058] The residual carbon content of 10% residual oil of refrigeration oil is preferably 0.01% by mass or more, 0.02% by mass or more, 0.05% by mass or more, 0.08% by mass or more, or 0.1% by mass or more, from the viewpoint of further reducing the friction coefficient, and for example, it can be 0.6% by mass or less, 0.5% by mass or less, or 0.4% by mass or less. It should be noted that the residual carbon content in this specification refers to the residual carbon content measured by the micro method in accordance with JIS K2270-2:2009. The residual carbon content of 10% residual oil in this specification refers to the residual carbon content measured by the same method for the residual oil after distillation of refrigeration oil and removal of distillate oil with a volume fraction of up to 90%.

[0059] The content of hydrocarbons having 12 to 16 carbon atoms (C12-16 component amount) in refrigeration oil or in the hydrocarbon base oil contained in the refrigeration oil can preferably be 80 mass % or more, 85 mass % or more, or 90 mass % or more, and can be 97 mass % or less, 96 mass % or less, or 95 mass % or less, based on the total amount of the hydrocarbon base oil, from the viewpoint of further reducing the friction coefficient.

[0060] The content of hydrocarbons having 13 to 18 carbon atoms (C13-18 component amount) in refrigeration oil or in the hydrocarbon base oil contained in the refrigeration oil can be preferably 80 mass % or more, 85 mass % or more, or 90 mass % or more, and can be 99 mass % or less, 98 mass % or less, or 97 mass % or less, based on the total amount of the hydrocarbon base oil, from the viewpoint of further reducing the friction coefficient.

[0061] The content of normal alkanes in the refrigeration oil or in the hydrocarbon base oil contained in the refrigeration oil may preferably be 0.5% by mass or more, 2% by mass or more, 5% by mass or more, 8% by mass or more, or 9% by mass or more, based on the total amount of the hydrocarbon base oil, from the viewpoint of further reducing the friction coefficient, and may further be 10% by mass or more, 15% by mass or more, or 20% by mass or more, and may be 50% by mass or less, 30% by mass or less, or 25% by mass or less, and from the viewpoint of low-temperature fluidity, may be 40% by mass or less, 30% by mass or less, 20% by mass or less, or 15% by mass or less.

[0062] The content of paraffins in refrigeration oil or in the hydrocarbon base oil contained in refrigeration oil may preferably be 30% by mass or more, 40% by mass or more, 50% by mass or more, 55% by mass or more, or 60% by mass or more, and may be 100% by mass or less, 90% by mass or less, or 80% by mass or less, based on the total amount of the hydrocarbon base oil, from the viewpoint of further reducing the friction coefficient.

[0063] The content of 1- to 6-ring cycloalkanes (hereinafter referred to as "cycloalkanes") in refrigeration oil or in the hydrocarbon base oil contained in the refrigeration oil may be preferably 70% by mass or less, 60% by mass or less, 50% by mass or less, 45% by mass or less, or 40% by mass or less, and may be 0% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, or 35% by mass or more, based on the total amount of hydrocarbon oil, from the viewpoint of further reducing the friction coefficient.

[0064] The ratio of the aforementioned chain alkane to the aforementioned cycloalkane (chain alkane / cycloalkane) is preferably 0.3 or more, 0.6 or more, 1.0 or more, 1.2 or more, 1.4 or more, 1.5 or more or 1.8 or more, and is preferably 100 or less, 50 or less, 10 or less, 5 or less or 4 or less, from the viewpoint of further reducing the friction coefficient.

[0065] The aromatic component in the refrigerating machine oil or the hydrocarbon base oil contained in the refrigerating machine oil may preferably be 10% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less from the viewpoint of further reducing the friction coefficient.

[0066] In this specification, the content of hydrocarbons with carbon numbers of 12 to 16, hydrocarbons with carbon numbers of 13 to 18, normal alkanes, chain alkanes, cycloalkanes and aromatic hydrocarbon oils in the above-mentioned refrigeration oil or in the hydrocarbon base oil contained in the refrigeration oil is obtained as follows: for the analysis object sample, silica gel chromatography is used to fractionate into saturated hydrocarbon oils and aromatic hydrocarbon oils, and for each, hydrocarbon type analysis based on GC-TOFMS method based on a combination of gas chromatography and mass spectrometry based on FI ionization method is used to obtain. An example of analysis conditions is shown below. According to the above-mentioned fractionation based on silica gel chromatography, the content of saturated hydrocarbon oil and aromatic hydrocarbon oil can also be obtained.

[0067] (Gas chromatography conditions)

[0068] Column: ZB-1MS manufactured by Phenomenex

[0069] Injection temperature: 350℃

[0070] Heating conditions: 50℃~350℃ (heating rate: 5℃ / min)

[0071] Carrier gas: Helium

[0072] Injection method: split flow

[0073] Sample injection volume: 1 μL (10% toluene solution)

[0074] (MS conditions)

[0075] Counter electrode voltage: -10kV

[0076] Ionization method: FI (field ionization)

[0077] Ion source temperature: room temperature

[0078] Mass number measurement range: m / z 35~500

[0079] In the mass spectrum obtained by GC-TOFMS analysis, the type of each carbon number (C n H 2n+z , where n represents an integer and z represents an even number of -18 to 2) is the ratio of different ionic strengths. In this specification, the content (mass %) of each component can be calculated as being substantially the same as the ionic strength % of each component. It should be noted that, when the aromatic hydrocarbon component of the sample according to silica gel chromatographic fractionation is less than 1 mass %, the chromatographic fractionation can be omitted and the hydrocarbon type analysis based on the GC-TOFMS method can be performed. In this case, all are regarded as saturated hydrocarbon components and the content of each component is calculated.

[0080] The refrigerator oil of this embodiment can exist in the refrigerator in the state of a refrigerator working fluid composition mixed with a refrigerant. That is, one embodiment of the present invention is a refrigerator working fluid composition, which contains: the above-mentioned refrigerator oil and a refrigerant. The content of the refrigerator oil in the refrigerator working fluid composition can be more than 1 mass part or more than 2 mass parts relative to 100 mass parts of the refrigerant, and can be less than 500 mass parts or less than 400 mass parts.

[0081] The refrigerant preferably contains hydrocarbons. The content of hydrocarbons may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more based on the total amount of the refrigerant.

[0082] The hydrocarbon is preferably a hydrocarbon having 1 to 5 carbon atoms, and more preferably a hydrocarbon having 2 to 4 carbon atoms. Specific examples of the hydrocarbon include methane, ethylene, ethane, propylene, propane (R290), cyclopropane, n-butane, isobutane (R600a), cyclobutane, methylcyclopropane, 2-methylbutane, n-pentane, or a mixture of two or more thereof. The hydrocarbon is preferably a hydrocarbon that is a gas at 25° C. and 1 atmosphere, and more preferably propane, n-butane, isobutane, 2-methylbutane, or a mixture thereof.

[0083] The refrigerant may contain, in addition to or in place of hydrocarbons, one or more selected from natural refrigerants such as saturated fluorinated hydrocarbons, unsaturated fluorinated hydrocarbons, fluorinated ethers such as perfluoroethers, bis(trifluoromethyl)sulfide, trifluoromethane iodide, ammonia, and carbon dioxide.

[0084] Example

[0085] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[0086] The hydrocarbon base oils A1 to A3 and a1 used in the examples and comparative examples are as follows. The aromatic components of these hydrocarbon base oils are less than 1% by mass, so they are not subjected to chromatographic fractionation, and all are regarded as saturated hydrocarbons, and the hydrocarbon type analysis based on the GC-TOFMS method described above is directly performed. The properties of these hydrocarbon base oils are shown in Table 1.

[0087] Hydrocarbon base oil A1: Mineral oil-based hydrocarbon oil obtained by hydrotreating and fractionating hydrocracked light oil containing vacuum distillation residue as a raw material (aromatic component <1 mass %, ASTM chromaticity: 0)

[0088] Hydrocarbon base oil A2: Mineral oil-based hydrocarbon oil obtained by hydrodesulfurizing and fractionating the atmospheric distillate of crude oil (aromatic component <1% by mass, ASTM color: 0)

[0089] Hydrocarbon base oil A3: Mineral oil-based hydrocarbon oil obtained by hydrodesulfurizing and fractionating the atmospheric distillate of crude oil (aromatic component <1 mass %, ASTM color: 0)

[0090] Hydrocarbon base oil a1: Mineral oil-based hydrocarbon oil obtained by hydrotreating and fractionating hydrocracked light oil containing a vacuum distillation residue as a raw material (aromatic component <1 mass %, ASTM chromaticity: 0)

[0091] [Table 1]

[0092]

[0093] Furthermore, a solvent extraction residue liquid of a deasphalted oil of a vacuum distillation residue oil was hydrotreated and solvent dewaxed to obtain a hydrocarbon base oil B having the following properties.

[0094] Hydrocarbon base oil B1 (40℃ kinematic viscosity: 479.4mm 2 / s, 100℃ kinematic viscosity: 31.72mm 2 / s, viscosity index 97, flash point: >300°C, residual carbon content: 0.51% by mass, ASTM chromaticity: L2.0)

[0095] Hydrocarbon base oil B2 (40℃ kinematic viscosity: 458mm 2 / s, 100℃ kinematic viscosity: 31.2mm 2 / s, viscosity index 98, flash point: >300°C, residual carbon content: 0.5% by mass, ASTM color: L2.0)

[0096] The above hydrocarbon base oils were used to prepare base oils of the composition shown in Table 2 (mass % based on the total amount of base oil). 98.3 mass % of each base oil and 1.7 mass % of a phosphorus-containing antiwear agent formed by a mixture of tricresyl phosphate and triphenyl thiophosphate (all based on the total amount of refrigeration oil) were mixed to prepare refrigeration oils. The hydrocarbon base oils contained in each refrigeration oil were subjected to the above hydrocarbon type analysis, and the results are shown in Table 2. In addition, the properties of each refrigeration oil are also shown in Table 2.

[0097] [Table 2]

[0098]

[0099] [Evaluation of Friction Characteristics]

[0100] In order to evaluate the friction characteristics of each refrigerating machine oil of the examples and comparative examples, the following tests were performed.

[0101] The friction coefficient (μ) in the lubrication field corresponding to the elastic fluid lubrication field or the mixed lubrication field was measured using an MTM (Mini Traction Machine) tester (manufactured by PCS Instruments) under the following conditions. The results are shown in Table 3. The smaller the friction coefficient, the better the friction characteristics.

[0102] Ball and disc: Standard test piece (AISI 52100 standard)

[0103] Test temperature: 40℃

[0104] Sliding speed: 0.3~0.9m / s (partial excerpt)

[0105] Load: 10N

[0106] Slide rate: 30%

[0107] It should be noted that the sliding speed uses |U D -U B | [m / s] Here, UD is the speed of the disk in the sliding part [m / s], and UB is the speed of the ball in the sliding part [m / s].

[0108] [Table 3]

[0109]

[0110] In addition, in Examples 5 to 7, hydrocarbon base oil A3 was used instead of hydrocarbon base oil A2 to prepare refrigeration oils of Examples 8 to 10. The refrigeration oils of Examples 8 to 10 obtained had a larger amount of normal paraffins and a slightly higher pour point than the refrigeration oils of Examples 5 to 7, but it was confirmed that the friction coefficient was further reduced.

[0111] (Low-temperature precipitation test in the presence of refrigerant)

[0112] Regarding the refrigerating machine oils of Examples 1 to 10, R600a, a hydrocarbon refrigerant, was used as a refrigerant, and a low-temperature precipitation test was performed according to Annex A of JIS K2211 (2009). The mixed fluids of the refrigerating machine oils of Examples 1 to 10 and R600a did not produce hairy precipitates, granular precipitates, fogging or turbidity even when cooled to -40°C, and no tendency of precipitation at low temperatures was confirmed.

Claims

1. A refrigeration oil comprising: 90% of a hydrocarbon base oil having a distillation temperature of 270°C or less, The content of hydrocarbons having 12 to 16 carbon atoms in the hydrocarbon base oil contained in the refrigerating machine oil is 80% by mass or more. The content of hydrocarbons having 13 to 18 carbon atoms in the hydrocarbon base oil contained in the refrigerating machine oil is 80% by mass or more.

2. The refrigerating machine oil according to claim 1, wherein The initial boiling point of the hydrocarbon base oil is 140° C. or higher.

3. The refrigerating machine oil according to claim 1 or 2, further comprising a phosphorus-containing antiwear agent.

4. The refrigerating machine oil according to claim 1 or 2, wherein: The flash point of the refrigeration oil is 70° C. or higher.

5. The refrigerating machine oil according to claim 1 or 2, wherein: The difference between the 90% distillation temperature and the 10% distillation temperature of the refrigerating machine oil is 5° C. or more and 40° C. or less.

6. The refrigerating machine oil according to claim 1 or 2, wherein: The residual carbon content of 10% residual oil of the refrigerating machine oil is 0.02 mass % or more.

7. The refrigerating machine oil according to claim 1 or 2, wherein: The content of normal paraffins in the hydrocarbon base oil contained in the refrigerating machine oil is 5 mass % or more and 50 mass % or less.

8. The refrigerating machine oil according to claim 1 or 2, wherein: The 90% distillation temperature of the refrigerating machine oil is 270° C. or lower.

9. A working fluid composition for a refrigerator, comprising: The refrigerating machine oil according to any one of claims 1 to 8, and refrigerant.

10. The working fluid composition for a refrigerator according to claim 9, wherein The refrigerant includes a hydrocarbon.

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