Refrigeration oil and refrigeration fluid components used in refrigeration equipment

Abstract

A refrigerator oil having a flash point of 130°C or lower and a residual carbon fraction of 10% residual oil of 0.02 mass% or more.

Description

[Technical Field]

[0001] The present invention relates to a refrigerating machine oil and a working fluid composition for a refrigerating machine. [Background technology]

[0002] In refrigerators, there is increasing pressure to replace refrigerants with relatively high Global Warming Potential (GWP) with low GWP refrigerants, for example, less than 150. Examples of low GWP refrigerants include carbon dioxide (R744) refrigerant and hydrocarbon refrigerants.

[0003] On the other hand, there is also a demand for energy conservation in refrigerators. Generally, the lower the viscosity of a refrigerator oil, the more it can reduce stirring resistance and friction in sliding parts, so lowering the viscosity of a refrigerator oil leads to energy conservation in refrigerators. For example, Patent Document 1 discloses a refrigerator oil with a viscosity of VG3 or higher and VG8 or lower. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2006 / 062245 Summary of the Invention [Problem to be solved by the invention]

[0005] One way to lower the viscosity of refrigerating machine oil is to increase the content of light components in the refrigerating machine oil. Refrigerating machine oils with a high content of light components can also be said to have a low flash point. However, if the flash point of a refrigerating machine oil is low (if the content of light components is high), it becomes difficult to maintain an oil film on sliding parts, which may result in a decrease in wear resistance, for example.

[0006] Therefore, one aspect of the present invention aims to provide a refrigerating machine oil that has a low flash point and excellent anti-wear properties. [Means for solving the problem]

[0007] According to the investigations of the present inventors, it has been found that even when the flash point of a refrigerating machine oil is low (for example, 130°C or lower), excellent wear resistance can be obtained as long as the residual carbon content of the 10% residual oil of the refrigerating machine oil is within a predetermined range.

[0008] One aspect of the present invention is a refrigerating machine oil having a flash point of 130°C or lower and a residual carbon content of 0.02 mass% or higher in a 10% residual oil.

[0009] The refrigeration oil has a kinematic viscosity of 6mm at 40°C. 2 / s or less, and a low-viscosity hydrocarbon oil having a kinematic viscosity of 200mm at 40°C. 2 The refrigerating machine oil may contain a high-viscosity hydrocarbon oil having a viscosity of 1 / s or more. The content of the low-viscosity hydrocarbon oil may be 85% by mass or more based on the total amount of the refrigerating machine oil. The content of the high-viscosity hydrocarbon oil may be 10% by mass or less based on the total amount of the refrigerating machine oil. The 90% distillation temperature of the refrigerating machine oil may be 270°C or less.

[0010] Another aspect of the present invention is a working fluid composition for a refrigerating machine, comprising the refrigerating machine oil and a refrigerant. The refrigerant may contain a hydrocarbon. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to provide a refrigerating machine oil that has a low flash point and excellent anti-wear properties. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention is a refrigerating machine oil having a flash point of 130°C or less and a residual carbon content of 0.02 mass% or more in a 10% residual oil.

[0013] 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 from the viewpoint of further reducing the viscosity of the refrigerating machine oil, it may be 125° C. or lower or 120° C. or lower. The flash point in this specification means a flash point measured in accordance with the Cleveland Open Chamber (COC) method described in JIS K2265-4:2007.

[0014] From the viewpoint of further improving wear resistance, the carbon residue of the 10% residual oil of the refrigerating machine oil may preferably be 0.05% by mass or more, 0.08% by mass or more, or 0.1% by mass or more, and may be, for example, 0.6% by mass or less, 0.5% by mass or less, or 0.4% by mass or less. In this specification, the carbon residue refers to the carbon residue measured by a micro method in accordance with JIS K2270-2:2009. In this specification, the carbon residue of the 10% residual oil refers to the carbon residue measured by the same method for the residual oil obtained by distilling the refrigerating machine oil and removing the distillate up to a volume fraction of 90%.

[0015] The kinematic viscosity of refrigerating machine oil at 40°C is, for example, 1 mm 2 / s or more, 1.5mm 2 / s or more, or 2 mm 2 / s or more, and 2 / s or less, 5mm 2 / s or less, 4.5mm 2 / s or less, 4mm 2 / s or less, 3.5mm 2 / s or less or 3mm 2 The kinematic viscosity in this specification refers to the kinematic viscosity measured in accordance with JIS K2283:2000.

[0016] The kinematic viscosity of refrigerating oil at 100°C is, for example, 0.5 mm 2 / s or more, 0.7mm 2 / s or more, or 1 mm 2 / s or more, and 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 1.1 mm 2 / s or less.

[0017] The density of refrigerating machine oil is, for example, 0.78 g / cm 3 More than 0.79g / cm 3 or more, or 0.80 g / cm 3 may be 0.85 g / cm or more, 3 Below, 0.84g / cm 3 or less than 0.83 g / cm 3 The density in this specification refers to the density at 15°C measured in accordance with the "oscillating method" described in JIS K2249-1:2011.

[0018] 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, or may be −60° C. or higher. In this specification, the pour point means the pour point measured in accordance with JIS K2269:1987.

[0019] The content of hydrocarbons having 12 to 16 carbon atoms in the refrigerating machine oil or in the hydrocarbon oil contained in the refrigerating machine oil (amount of C12-16 components) may be preferably 80 mass% or more, 85 mass% or more, or 90 mass% or more, and may be 97 mass% or less, 96 mass% or less, or 95 mass% or less, based on the total amount of the hydrocarbon oil, from the viewpoint of further improving wear resistance.

[0020] The content of hydrocarbons having 13 to 18 carbon atoms in the refrigerating machine oil or in the hydrocarbon oil contained in the refrigerating machine oil (amount of C13-18 components) may be preferably 80 mass% or more, 85 mass% or more, or 90 mass% or more, and may be 99 mass% or less, 98 mass% or less, or 97 mass% or less, based on the total amount of the hydrocarbon oil, from the viewpoint of further improving wear resistance.

[0021] The content of n-paraffins in the refrigerating machine oil or in the hydrocarbon oil contained therein may be preferably 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, and 50% by mass or less, 30% by mass or less, or 25% by mass or more, based on the total amount of the hydrocarbon oil, from the viewpoint of further improving wear resistance, and may be 40% by mass or less, 30% by mass or less, 20% by mass or less, or 15% by mass or less, from the viewpoint of low-temperature fluidity. Furthermore, the content of n-paraffins may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, from the viewpoint of further reducing the coefficient of friction.

[0022] From the viewpoint of further reducing the friction coefficient, the content of paraffin in the refrigerating machine oil or in the hydrocarbon oil contained in the refrigerating machine oil may be preferably 30 mass% or more, 40 mass% or more, 50 mass% or more, 55 mass% or more, or 60 mass% or more, and may be 100 mass% or less, 90 mass% or less, or 80 mass% or less, based on the total amount of the hydrocarbon oil.

[0023] The content of 1- to 6-ring cycloparaffins (hereinafter simply referred to as "cycloparaffins") in the refrigerating machine oil or in the hydrocarbon oil contained in the refrigerating machine oil may be, from the viewpoint of being able to further reduce the friction coefficient, preferably 70 mass % or less, 60 mass % or less, 50 mass % or less, 45 mass % or less, or 40 mass % or less, and may be 0 mass % or more, 10 mass % or more, 20 mass % or more, 30 mass % or more, or 35 mass % or more, based on the total amount of the hydrocarbon oil.

[0024] From the viewpoint of further reducing the friction coefficient, the ratio of the paraffin to the cycloparaffin (paraffin / cycloparaffin) may be 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 may be preferably 100 or less, 50 or less, 10 or less, 5 or less, or 4 or less.

[0025] The aromatic content in the refrigerating machine oil or in the hydrocarbon oil contained in the refrigerating machine oil may be preferably 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.

[0026] In this specification, the contents of hydrocarbons having 12 to 16 carbon atoms, hydrocarbons having 13 to 18 carbon atoms, n-paraffins, paraffins, cycloparaffins, and aromatic hydrocarbon oils in the refrigerating machine oil or the hydrocarbon oil contained therein are determined by fractionating the sample to be analyzed into saturated hydrocarbon oils and aromatic hydrocarbon oils by silica gel chromatography, and then performing hydrocarbon type analysis on each of the oils using GC-TOFMS, which combines gas chromatography with mass spectrometry using FI ionization. Examples of analytical conditions are shown below. The contents of saturated hydrocarbon oils and aromatic hydrocarbon oils may also be determined by fractionation using silica gel chromatography. (Gas chromatography conditions) Column: phenomenex ZB-1MS Injection temperature: 350℃ Temperature rise conditions: 50℃ to 350℃ (heat rise rate: 5℃ / min) Carrier gas: Helium Injection method: Split Sample injection volume: 1 μL (10% toluene solution) (MS conditions) Counter electrode voltage: -10kV Ionization method: FI (field ionization) Ion source temperature: room temperature Mass number measurement range: m / z 35-500

[0027] Among the mass spectra obtained as a result of GC-TOFMS analysis, the types of carbon numbers (C n H 2n+zThe percentage of ionic strength of each component (where n is an integer and z is an even number between -18 and 2) can be calculated from the percentage of total ionic strength, and in this specification, the content (mass %) of each component is assumed to be approximately the same as the ionic strength % of each component. Note that if the aromatic hydrocarbon content of a sample fractionated by silica gel chromatography is less than 1 mass %, this chromatographic fractionation may be omitted and hydrocarbon type analysis performed by GC-TOFMS. In this case, the content of each component is calculated assuming that all components are saturated hydrocarbons.

[0028] The refrigerating machine oil may have the distillation properties described below. Hereinafter, the distillation properties of the refrigerating machine oil and the hydrocarbon oil contained therein are all measured in accordance with the atmospheric pressure method described in JIS K2254:2018.

[0029] From the viewpoint of further improving wear resistance, the initial boiling point (IBP) of the refrigerating machine oil may preferably be 140°C or more, 170°C or more, 190°C or more, 200°C or more, 210°C or more, 220°C or more, 230°C or more, or 240°C or more, and may be 260°C or less, 255°C or less, or 250°C or less.

[0030] From the viewpoint of further improving the wear resistance, the 10% distillation temperature (T10) of the refrigerating machine oil may preferably be 200°C or more, 210°C or more, 220°C or more, 230°C or more, or 240°C or more, and may be 260°C or less, 255°C or less, or 250°C or less.

[0031] From the viewpoint of further improving wear resistance, the 50% distillation temperature (T50) of the refrigerating machine oil may preferably be 210°C or more, 220°C or more, 230°C or more, 240°C or more, or 245°C or more, and may be 265°C or less, 260°C or less, 255°C or less, or 250°C or less.

[0032] From the viewpoint of further improving wear resistance, the 90% distillation temperature (T90) of the refrigerating machine oil may preferably be 220°C or more, 230°C or more, 240°C or more, 245°C or more, or 250°C or more, and may be 270°C or less, 267°C or less, 266°C or less, 265°C or less, 264°C or less, 263°C or less, 262°C or less, or 261°C or less.

[0033] From the viewpoint of further improving wear resistance, the distillation end point (EP) of the refrigerating machine oil may preferably be 250°C or more, 260°C or more, 270°C or more, 275°C or more, or 280°C or more, and may be 320°C or less, 310°C or less, 300°C or less, 295°C or less, or 290°C or less.

[0034] From the viewpoint of further improving the wear resistance, the difference between T90 and T10 of the refrigerating machine oil (T90 - T10) 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.

[0035] The total distillate amount of the refrigerating machine oil may be, for example, 90% by volume or more, 93% by volume or more, or 95% by volume or more, or may be 99% by volume or less. The residual amount of the refrigerating machine oil may 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 amount of the refrigerating machine oil may be, for example, 1% by volume or less, 0.5% by volume or less, or 0.1% by volume or less, or may be 0% by volume.

[0036] The refrigeration oils described above contain, for example, hydrocarbon oils. Examples of hydrocarbon oils include mineral hydrocarbon oils, synthetic hydrocarbon oils, and mixtures thereof. Examples of mineral hydrocarbon oils include paraffinic or naphthenic refined mineral oils that are obtained by using crude oil or its distillation residue as a raw material and refining it through an appropriate combination of conventional petroleum refining processes (solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, distillation, etc.). Examples of synthetic hydrocarbon oils include poly-α-olefins or hydrogenated products thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes, etc. These hydrocarbon oils can be used alone or in combination of two or more.

[0037] From the viewpoint of further improving the wear resistance, the refrigeration oil is preferably a hydrocarbon oil having a kinematic viscosity of 6 mm at 40°C. 2 / s or less, and a low-viscosity hydrocarbon oil having a kinematic viscosity of 200mm at 40°C. 2 and a high viscosity hydrocarbon oil having a viscosity of 1 / s or more.

[0038] The kinematic viscosity of low-viscosity hydrocarbon oil at 40°C is, for example, 1 mm 2 / s or more, 1.5mm 2 / s or more, or 2 mm 2 / s or more, 5 mm 2 / s or less, 4.5mm 2 / s or less, 4mm 2 / s or less, 3.5mm 2 / s or less or 3mm 2 / s or less.

[0039] The kinematic viscosity of low-viscosity hydrocarbon oil at 100°C is, for example, 0.5 mm 2 / s or more, 0.7mm 2 / s or more, or 1 mm 2 / s or more, and 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 1.1 mm 2 / s or less.

[0040] The density of the low viscosity hydrocarbon oil is, for example, 0.78 g / cm 3 More than 0.79g / cm 3 More than 0.80g / cm 3 More than 0.81g / cm 3 or more, or 0.82 g / cm 3 or more, and 3 Below, 0.83g / cm 3 Below, 0.82g / cm 3 or less than 0.81 g / cm 3 It may be the following:

[0041] The flash point of the low-viscosity hydrocarbon oil may be, for example, 30°C or higher, 60°C or higher, 90°C or higher, 100°C or higher, or 110°C or higher, and from the viewpoint of further reducing the viscosity of the refrigerating machine oil, it may be 130°C or lower, 125°C or lower, or 120°C or lower.

[0042] The pour point of the low-viscosity hydrocarbon 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.

[0043] From the viewpoint of further improving wear resistance, the 90% distillation temperature (T90) of the low-viscosity hydrocarbon oil may be preferably 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, or 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.

[0044] From the viewpoint of further improving wear resistance, the initial boiling point (IBP) of the low-viscosity hydrocarbon oil may be preferably 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.

[0045] From the viewpoint of further improving wear resistance, the 10% distillation temperature (T10) of the low-viscosity hydrocarbon 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.

[0046] From the viewpoint of further improving wear resistance, the 50% distillation temperature (T50) of the low-viscosity hydrocarbon oil may preferably be 210°C or more, 220°C or more, 230°C or more, 240°C or more, or 245°C or more, and may be 265°C or less, 260°C or less, 255°C or less, or 250°C or less.

[0047] From the viewpoint of further improving the wear resistance, the distillation end point (EP) of the low-viscosity hydrocarbon oil may be preferably 250°C or more, 260°C or more, 270°C or more, 275°C or more, or 280°C or more, and may be 320°C or less, 310°C or less, 300°C or less, 295°C or less, or 290°C or less.

[0048] From the viewpoint of further improving wear resistance, the difference between T90 and T10 of the low-viscosity hydrocarbon oil (T90-T10) may be preferably 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.

[0049] The total distillate amount of the low-viscosity hydrocarbon 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 may be 99.9% by volume or less. The residual amount of the low-viscosity hydrocarbon oil may be, for example, 0.1% by volume or more, and may be 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 low-viscosity hydrocarbon oil may be, for example, 1% by volume or less, 0.5% by volume or less, or 0.1% by volume or less, or may be 0% by volume.

[0050] Low-viscosity hydrocarbon oils can be obtained, for example, by hydrorefining kerosene and diesel fractions obtained by atmospheric distillation of crude oil, or cracked diesel fractions obtained by cracking residual oil feedstocks including atmospheric residues of crude oil or their vacuum residues, and fractionating the resulting oil to have the above-mentioned distillation properties, particularly such that hydrocarbons having 12 to 16 carbon atoms or 13 to 18 carbon atoms constitute the main components (for example, 50 mass% or more, particularly 80 mass% or more).

[0051] The content of the low-viscosity hydrocarbon oil, based on the total amount of hydrocarbon oil contained in the refrigerating machine oil, may be preferably 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, and may be, for example, 99.5% by mass or less, from the viewpoint of further lowering the viscosity of the refrigerating machine oil. ...

[0052] From the viewpoint of further improving the wear resistance, the kinematic viscosity of the high-viscosity hydrocarbon oil at 40°C is preferably 300 mm 2 / s or more, 350mm 2 / s or more, 400mm 2 / s or more, or 450 mm 2 / s or more, for example, 1000 mm 2 / s or less, 800mm 2 / s or less, 600mm 2 / s or less, or 500 mm 2 / s or less.

[0053] The kinematic viscosity of high viscosity hydrocarbon oil at 100°C is, for example, 10 mm 2 / s or more, 20mm 2 / s or more, or 30 mm 2 / s or more, and 2 / s or less, 50mm 2 / s or less, or 40 mm 2 / s or less.

[0054] The viscosity index of the high-viscosity hydrocarbon oil may be, for example, 0 or more, 50 or more, or 80 or more, and may be 300 or less, 140 or less, or 100 or less. The viscosity index in this specification means a viscosity index measured in accordance with JIS K2283:2000.

[0055] The flash point of the high viscosity hydrocarbon oil 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.

[0056] The high-viscosity hydrocarbon oil is preferably one having the above properties, and is not otherwise particularly limited, but for example, a residual hydrocarbon base material from a crude oil refining process can be used. Examples of residual hydrocarbon base materials include atmospheric distillation residual oil of crude oil, vacuum distillation residual oil of the atmospheric distillation residual oil, deasphalted oil of these residual oils with propane or the like, solvent extracted extract oil of the deasphalted oil with furfural or the like, solvent extracted raffinate oil of the deasphalted oil, and refined oil obtained by refining these oils with hydrocracking, hydrorefining, solvent dewaxing, or hydrodewaxing. Among these, refined oil obtained by hydrorefining solvent extracted raffinate of deasphalted oil of vacuum distillation residual oil, and solvent dewaxing or hydrodewaxing is particularly preferred.

[0057] The residual carbon content of the high-viscosity hydrocarbon oil is not particularly limited, but in terms of further improving wear resistance, it may be preferably 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more, and may be preferably 10% by mass or less, 5% by mass or less, 1% by mass or less, or 0.8% by mass or less.

[0058] From the viewpoint of the hue of the refrigeration oil, the ASTM color of the high-viscosity hydrocarbon oil B may be 6.0 or less, 4.0 or less, or 3.0 or less, and may be L0.5, 0.5 or more, or 1.0 or more.

[0059] The content of the high-viscosity hydrocarbon oil, based on the total amount of hydrocarbon oil contained in the refrigerating machine oil, may be preferably 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 3% by mass or more, and may be, for example, 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less, or 5% by mass or less. The content of the high-viscosity hydrocarbon oil, based on the total amount of refrigerating machine oil, may be preferably 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 3% by mass or more, and may be, for example, 10% by mass or less, 9% by mass or less, 8% by mass or less, 7% by mass or less, 6% by mass or less, or 5% by mass or less.

[0060] The refrigerating machine oil may further contain a hydrocarbon oil other than the above-mentioned low-viscosity hydrocarbon oil and high-viscosity hydrocarbon oil, and may further contain an oxygen-containing oil. The refrigerating machine oil may further contain additives. Examples of additives include antiwear agents, antioxidants, acid scavengers, extreme-pressure agents, metal deactivators, pour-point depressants, detergents and dispersants. The content of these additives may be 10% by mass or less or 5% by mass or less based on the total amount of the refrigerating machine oil.

[0061] From the viewpoint of improving wear resistance, the refrigerating machine oil preferably contains an anti-wear agent as an additive. Examples of the anti-wear agent include phosphorus-containing anti-wear agents. Examples of the phosphorus-containing anti-wear agent include phosphate esters, thiophosphate esters, acid phosphate esters, amine salts of acid phosphate esters, and chlorinated phosphate esters. The anti-wear agent (preferably phosphorus-containing anti-wear agents) is used alone or in combination of two or more. The phosphorus-containing anti-wear agent is preferably one or more selected from phosphate esters and thiophosphate esters.

[0062] 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, tri(ethylphenyl)phosphate, tri(butylphenyl)phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, etc. The phosphoric acid ester is preferably triphenyl phosphate or tricresyl phosphate.

[0063] Examples of thiophosphate esters 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, trixylenyl phosphorothioate, cresyl diphenyl phosphorothioate, and xylenyl diphenyl phosphorothioate. The thiophosphate is preferably triphenyl phosphorothioate.

[0064] The content of the anti-wear agent (preferably a phosphorus-containing anti-wear agent) may be, for example, 0.1 mass % or more, 0.5 mass % or more, or 1 mass % or more, and may be 5 mass % or more, 4 mass % or less, or 3 mass % or less, based on the total amount of the refrigerating machine oil.

[0065] The refrigerating machine oil according to this embodiment may be present in a refrigerating machine in the form of a working fluid composition for a refrigerating machine mixed with a refrigerant. That is, one embodiment of the present invention is a working fluid composition for a refrigerating machine containing the above-mentioned refrigerating machine oil and a refrigerant. The content of the refrigerating machine oil in the working fluid composition for a refrigerating machine 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, per 100 parts by mass of the refrigerant.

[0066] The refrigerant preferably contains a hydrocarbon, and the hydrocarbon content 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.

[0067] The hydrocarbon is preferably a hydrocarbon having 1 to 5 carbon atoms, more preferably a hydrocarbon having 2 to 4 carbon atoms. Specific examples of the hydrocarbon include methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane (R600a), cyclobutane, methylcyclopropane, 2-methylbutane, normal pentane, or a mixture of two or more of these. The hydrocarbon is preferably a gaseous hydrocarbon at 25°C and 1 atmospheric pressure, more preferably propane, normal butane, isobutane, 2-methylbutane, or a mixture of these.

[0068] In addition to or instead of hydrocarbons, the refrigerant may contain one or more refrigerants selected from saturated fluorohydrocarbons, unsaturated fluorohydrocarbons, fluorine-containing ethers such as perfluoroethers, bis(trifluoromethyl) sulfide, trifluoroiodomethane, and natural refrigerants such as ammonia and carbon dioxide. [Example]

[0069] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0070] The low-viscosity hydrocarbon oils 1 to 3 used in the examples and comparative examples are as follows. Because the aromatic content of these hydrocarbon oils was less than 1% by mass, chromatographic fractionation was not performed, and they were all considered to be saturated hydrocarbons, and the hydrocarbon type analysis was directly performed using the GC-TOFMS method described above. The properties of these low-viscosity hydrocarbon oils are shown in Table 1. Low viscosity hydrocarbon oil 1: Mineral hydrocarbon oil (aromatic content <1% by mass, ASTM color: 0) obtained by hydrotreating and fractionating hydrocracked diesel fuel containing vacuum distillation residue. Low viscosity hydrocarbon oil 2: Mineral hydrocarbon oil obtained by hydrodesulfurizing and fractionating crude oil atmospheric distillate (aromatic content <1% by mass, ASTM color: 0) Low viscosity hydrocarbon oil 3: Mineral hydrocarbon oil obtained by hydrodesulfurizing and fractionating crude oil atmospheric distillate (aromatic content <1% by mass, ASTM color: 0)

[0071] [Table 1]

[0072] Furthermore, the solvent extracted raffinate of the deasphalted oil of the vacuum distillation residue was hydrorefined and solvent dewaxed to obtain high viscosity hydrocarbon oils 1 and 2 having the properties shown below. High viscosity hydrocarbon oil 1 (40℃ kinematic viscosity: 479.4mm 2 / s, 100℃ kinematic viscosity: 31.72mm 2 / s, viscosity index 97, flash point: >300℃, residual carbon content: 0.51% by mass, ASTM color: L2.0) High viscosity hydrocarbon oil 2 (40°C kinematic viscosity: 458mmHg 2 / s, 100℃ kinematic viscosity: 31.2mm 2 / s, viscosity index 98, flash point: >300℃, residual carbon content: 0.5% by mass, ASTM color: L2.0)

[0073] The above hydrocarbon oils were used in the compositions (% by mass based on the total amount of hydrocarbon oil) shown in Table 2. Refrigerating machine oils were prepared by mixing 98.3% by mass of each hydrocarbon oil with 1.7% by mass of a phosphorus-containing antiwear agent consisting of a mixture of tricresyl phosphate and triphenyl phosphorothioate (all based on the total amount of refrigerating machine oil). The hydrocarbon type analysis was carried out on the hydrocarbon oil contained in each refrigerating machine oil, and the results are shown in Table 2. Table 2 also shows the properties of each refrigerating machine oil.

[0074] [Wear resistance evaluation] Wear resistance was measured in accordance with ASTM D3233-73 using a Falex (pin / V-block) testing machine at a temperature of 60°C and a rotation speed of 290 rpm, measuring the seizure load. A higher seizure load indicates better wear resistance. The results are shown in Table 2.

[0075] [Table 2]

[0076] Furthermore, in each of Examples 5 and 6, low-viscosity hydrocarbon oil 2 was replaced with low-viscosity hydrocarbon oil 3 to prepare refrigerating machine oils of Examples 7 and 8. The obtained refrigerating machine oils of Examples 7 and 8 had a larger amount of n-paraffin and a slightly higher pour point than the refrigerating machine oils of Examples 5 and 6, respectively, but were confirmed to have equal or greater improvements in wear resistance and low friction.

[0077] (Low temperature precipitation test in the presence of refrigerant) For the refrigerating machine oils of Examples 1 to 8, a low-temperature precipitation test was carried out in accordance with JIS K2211 (2009) Appendix A, using the hydrocarbon refrigerant R600a as the refrigerant. When the mixed fluids of the refrigerating machine oils of Examples 1 to 8 and R600a had a refrigerating machine oil / refrigerant ratio (mass ratio) in the range of 1 / 99 to 99 / 1, no hairy precipitates, granular precipitates, cloudiness or turbidity were generated even when cooled to -40°C, and no tendency for precipitation at low temperatures was observed.

Claims

1. The flash point is 130°C or less, and the residual carbon content of 10% residual oil is 0.02% by mass or more, a low-viscosity hydrocarbon oil having a kinematic viscosity at 40°C of 6 mm 2 / s or less; A refrigeration oil comprising: a high-viscosity hydrocarbon oil having a kinematic viscosity at 40°C of 200 mm 2 / s or more;

2. 2. The refrigerating machine oil according to claim 1, wherein the content of the low-viscosity hydrocarbon oil is 85 mass % or more based on the total amount of the refrigerating machine oil.

3. 3. The refrigerating machine oil according to claim 1, wherein the content of the high-viscosity hydrocarbon oil is 10 mass % or less based on the total amount of the refrigerating machine oil.

4. The refrigerating machine oil according to any one of claims 1 to 3, wherein the 90% distillation temperature of the refrigerating machine oil is 270°C or lower.

5. The refrigerating machine oil according to any one of claims 1 to 4, A working fluid composition for a refrigerating machine, comprising:

6. The working fluid composition for a refrigerating machine according to claim 5 , wherein the refrigerant comprises a hydrocarbon.

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