JP6748690B2 - Refrigerating machine oil and working fluid composition for refrigerator - Google Patents

Description

The present invention relates to a refrigerating machine oil, a working fluid composition for a refrigerating machine, an application of a composition containing an alkylbenzene as a base oil to a refrigerating machine oil or a working fluid composition for a refrigerating machine, and a refrigerating machine oil for an alkylbenzene or a working fluid for a refrigerator. Application for the manufacture of a composition.

Conventionally, refrigerating machine oil is used as lubricating oil for a refrigerant compressor in refrigerators such as refrigerators and refrigerating air conditioners. For example, a refrigerating machine oil containing an alkylbenzene as a base oil is known as a refrigerating machine oil for an HFC (hydrofluorocarbon) refrigerant (see, for example, Patent Document 1).

As described in Patent Document 1, alkylbenzene exhibits a weak compatibility with an HFC refrigerant, and particularly in an accumulator provided on the low pressure side of a refrigerant circulation system, the solubility of refrigerating machine oil in a liquid refrigerant decreases. Therefore, when a refrigerating machine oil containing alkylbenzene as a base oil is used, the oil return from the accumulator is an important issue from the viewpoint of the reliability of the compressor. Due to such circumstances, in conventional refrigerating machine oil, it is general to use alkylbenzene which has low viscosity and excellent fluidity.

JP, 10-246521, A

By the way, some of the HFC refrigerants used recently have a slight flammability. According to the study by the present inventor, when a conventional refrigerating machine oil containing alkylbenzene as a base oil is applied to a refrigerator using a slightly flammable HFC refrigerant, it is difficult to achieve both oil return and flame retardancy. It turned out to be

Therefore, an object of the present invention is to provide a refrigerating machine oil capable of achieving both oil return and flame retardancy and a working fluid composition for a refrigerating machine containing the refrigerating machine oil.

The present invention provides a refrigerating machine oil that contains an alkylbenzene having a 5% distillation temperature of 250°C or higher and a 95% distillation temperature of 460°C or lower as a base oil and is used with a slightly flammable hydrofluorocarbon refrigerant.

The 5% distillation temperature and the 95% distillation temperature in the present invention are the 5% distillation temperature and the 95% distillation temperature, respectively, measured according to the distillation test method by gas chromatography specified in ASTM D7213-05. Means

The present invention also provides a working fluid composition for a refrigerating machine containing the refrigerating machine oil described above and a slightly flammable hydrofluorocarbon refrigerant.

The present invention also relates to application of a composition containing alkylbenzene as a base oil to a refrigerating machine oil or a working fluid composition for a refrigerating machine, wherein the alkylbenzene is 5% distillation temperature of 250°C or higher and 95% of 460°C or lower. A refrigerating machine oil having a% distillation temperature is used with a slightly flammable hydrofluorocarbon refrigerant, and a working fluid composition for a refrigerating machine contains a refrigerating machine oil and a slightly flammable hydrofluorocarbon refrigerant. ..

The present invention is also an application for producing a refrigerating machine oil or a working fluid composition for a refrigerating machine of alkylbenzene, wherein the alkylbenzene has a 5% distillation temperature of 250°C or higher and a 95% distillation temperature of 460°C or lower. Refrigerating machine oil is used together with a slightly flammable hydrofluorocarbon refrigerant, and a working fluid composition for a refrigerating machine contains a refrigerating machine oil and a slightly flammable hydrofluorocarbon refrigerant.

ADVANTAGE OF THE INVENTION According to this invention, the refrigerating machine oil which can make oil return property and flame retardancy compatible, and the working fluid composition for refrigerators containing this refrigerating machine oil can be provided.

It is a graph which shows an example of the relationship between the distillation amount and the distillation temperature of the alkylbenzene which concerns on this embodiment. 3 is a table showing an example of the relationship between the distillation amount of alkylbenzene and the distillation temperature according to the present embodiment. It is a schematic diagram of the apparatus used for the oil return property test in an Example.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The refrigerating machine oil according to the present embodiment contains alkylbenzene having a 5% distillation temperature of 250°C or higher and a 95% distillation temperature of 460°C or lower as a base oil, and is used together with a slightly flammable hydrofluorocarbon refrigerant. The working fluid composition for a refrigerator according to the present embodiment contains the refrigerating machine oil and a slightly flammable hydrofluorocarbon refrigerant.

Refrigerating machine oil contains alkylbenzene as a base oil. The 5% distillation temperature of alkylbenzene is preferably 250° C. or higher, more preferably 255° C. or higher, and further preferably 260° C. or higher from the viewpoint of improving flame retardancy. The 95% distillation temperature of alkylbenzene is preferably 460° C. or lower, more preferably 455° C. or lower, still more preferably 450° C. or lower, from the viewpoint of improving the oil return property. In addition, by setting the 95% distillation temperature of alkylbenzene within the above range, abrasion resistance tends to be improved. Specifically, the alkylbenzene according to the present embodiment has a distillation property (relationship between the distillation amount and the distillation temperature) as shown in FIGS. 1 and 2, for example.

The 5% distillation temperature and the 95% distillation temperature in the present invention are the 5% distillation temperature and the 95% distillation temperature, respectively, measured according to the distillation test method by gas chromatography specified in ASTM D7213-05. Means

As the alkylbenzene having the above characteristics, the following alkylbenzene (A) and/or alkylbenzene (B) can be used.
Alkylbenzene (A): an alkylbenzene having 1 to 4 alkyl groups having 1 to 19 carbon atoms and having a total carbon number of 9 to 19 (preferably 1 alkyl group having 1 to 15 carbon atoms). ~ Alkylbenzene having 4 and the total number of carbon atoms of the alkyl group is 9 to 15)
Alkylbenzene (B): Alkylbenzene having 1 to 4 alkyl groups having 1 to 40 carbon atoms and having a total carbon number of 20 to 40 of the alkyl groups (preferably 1 alkyl group having 1 to 30 carbon atoms). ~ Alkylbenzene having 4 and the total number of carbon atoms of the alkyl group is 20 to 30)

Specific examples of the alkyl group having 1 to 19 carbon atoms in the alkylbenzene (A) include a methyl group, an ethyl group, a propyl group (including all isomers, the same applies hereinafter), a butyl group, a pentyl group, and a hexyl group. Group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group. These alkyl groups may be linear or branched, and are preferably branched in terms of stability, viscosity characteristics and the like. Particularly, from the viewpoint of availability, a branched alkyl group derived from an olefin oligomer such as propylene, butene and isobutylene is more preferable.

The number of alkyl groups in the alkylbenzene (A) is 1 to 4, and preferably 1 or 2 (that is, monoalkylbenzene, dialkylbenzene, or a mixture thereof) from the viewpoint of stability and availability. is there.

The alkylbenzene (A) may contain only an alkylbenzene having a single structure, has 1 to 4 alkyl groups having 1 to 19 carbon atoms, and has a total carbon number of 9 to 19 of the alkyl groups. A mixture of alkylbenzenes having different structures may be contained as long as they satisfy the conditions.

Specific examples of the alkyl group having 1 to 40 carbon atoms in the alkylbenzene (B) include a methyl group, an ethyl group, a propyl group (including all isomers, the same applies hereinafter), a butyl group, a pentyl group, and a hexyl group. Group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, henicosyl group, docosyl group, Tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, hentriacontyl group, dotriacontyl group, tritriacontyl group, tetratriacontyl group, pentatriacontyl group, hexa Examples thereof include triacontyl group, heptatriacontyl group, octatriacontyl group, nonatriacontyl group, and tetracontyl group. These alkyl groups may be linear or branched, and are preferably branched in terms of stability, viscosity characteristics and the like. Particularly, from the viewpoint of availability, a branched alkyl group derived from an olefin oligomer such as propylene, butene and isobutylene is more preferable.

The number of alkyl groups in the alkylbenzene (B) is 1 to 4, and preferably 1 or 2 (that is, monoalkylbenzene, dialkylbenzene, or a mixture thereof) from the viewpoint of stability and availability. is there.

The alkylbenzene (B) may contain only a single-structure alkylbenzene, has 1 to 4 alkyl groups having 1 to 40 carbon atoms, and has a total carbon number of 20 to 40. A mixture of alkylbenzenes having different structures may be contained as long as they satisfy the conditions.

The kinematic viscosity of the alkylbenzene at 40° C. is preferably 3 mm ² /s or more, more preferably 4 mm ² /s or more, still more preferably 5 mm ² /s or more, from the viewpoint of improving lubricity. The kinematic viscosity of the alkylbenzene at 40° C. is preferably 100 mm ² /s or less, more preferably 80 mm ² /s or less, still more preferably 70 mm ² /s or less, from the viewpoint of improving the oil return property. The kinematic viscosity in the present invention means the kinematic viscosity measured according to JIS K2283:2000.

The flash point of alkylbenzene is preferably 150° C. or higher, more preferably 155° C. or higher, and even more preferably 160° C. or higher, from the viewpoint of improving flame retardancy. The flash point in the present invention means the flash point measured according to JIS K2265-4.

From the viewpoint of improving flame retardancy, the spontaneous ignition point of alkylbenzene is preferably 340° C. or higher, more preferably 345° C. or higher, and further preferably 350° C. or higher. The spontaneous ignition point in the present invention means the spontaneous ignition point measured by the method according to ASTM E 659-1978.

The method for producing alkylbenzene is not limited, but the following production method is exemplified.

For example, a cylindrical fixed-bed continuous flow reactor is filled with an alkylation catalyst, and an aromatic compound and an alkylating agent are continuously supplied to the reactor from a raw material supply line to react the aromatic compound and the alkylating agent. Let In the reactor, for example, the reaction temperature is 180 to 240° C., the reaction pressure is 0.6 to 1.1 MPa, the alkylating agent/aromatic compound (molar ratio) at the reactor inlet is 1.0, and the liquid flow rate is LHSV=1.4 to 1.8. Then, the obtained reaction mixture is continuously sent to the distillation column through the transfer line. In the distillation column, for example, the theoretical plate number is 70 to 90, the pressure is 140 to 160 mmHg, the column top temperature is 180 to 200°C, and the column bottom temperature is 230 to 270°C. By setting each condition in the distillation column in this way, the alkylbenzene according to this embodiment is produced.

Examples of the above-mentioned aromatic compounds include benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene, and mixtures thereof. Examples of the above alkylating agent include lower monoolefins such as ethylene, propylene, butene, and isobutylene, preferably linear or branched olefins having 6 to 40 carbon atoms obtained by polymerization of propylene; waxes, heavy Straight chain or branched olefin having 6 to 40 carbon atoms obtained by thermal decomposition of heavy oil, petroleum fraction, polyethylene, polypropylene, etc.; n-paraffin is separated from petroleum fraction of kerosene, light oil, etc. A linear olefin having 6 to 40 carbon atoms obtained by olefination with a catalyst; and a mixture thereof are used. As the above alkylation catalyst, known catalysts such as Friedel-Crafts type catalysts such as aluminum chloride and zinc chloride; acidic catalysts such as sulfuric acid, phosphoric acid, silicotungstic acid, hydrofluoric acid and activated clay; ..

The content of alkylbenzene can be 50% by mass or more, 70% by mass or more, 80% by mass or more, and 90% by mass or more, based on the total amount of the refrigerating machine oil. it can.

The refrigerating machine oil may contain a base oil composed of alkylbenzene, and may further contain another base oil in addition to the alkylbenzene. Other base oils include mineral oils, hydrocarbon oils such as olefin polymers, esters (monoesters, polyol esters containing straight chain fatty acids and/or branched fatty acids as constituent fatty acids, etc.), polyglycols, polyvinyl ethers, ketones, poly Oxygenated oils such as phenyl ether, silicone, polysiloxane and perfluoroether are exemplified.

The refrigerator oil may further contain additives in addition to the base oil.

Examples of the additive include an epoxy compound. Examples of epoxy compounds include glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, oxirane compounds, alkyloxirane compounds, alicyclic epoxy compounds, epoxidized fatty acid monoesters, and epoxidized vegetable oils. These epoxy compounds can be used individually by 1 type or in combination of 2 or more types.

［式（１）中、Ｒ^１はアリール基又は炭素数５〜１８のアルキル基を示す。］ As the glycidyl ether type epoxy compound, for example, an aryl glycidyl ether type epoxy compound or an alkyl glycidyl ether type epoxy compound represented by the following general formula (1) can be used.

[In the formula (1), R ¹ represents an aryl group or an alkyl group having 5 to 18 carbon atoms. ]

Examples of the glycidyl ether type epoxy compound represented by the formula (1) include n-butylphenyl glycidyl ether, i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether, and hexyl. Phenyl glycidyl ether, heptyl phenyl glycidyl ether, octyl phenyl glycidyl ether, nonyl phenyl glycidyl ether, decyl phenyl glycidyl ether, decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl Glycidyl ether is preferred.

When the alkyl group represented by R ¹ has 5 or more carbon atoms, the stability of the epoxy compound is ensured, and the epoxy compound is decomposed before reacting with water, fatty acid, and oxidative deterioration product, or the epoxy compounds are polymerized with each other. The occurrence of polymerization can be suppressed, and the desired function can be easily obtained. On the other hand, when the number of carbon atoms of the alkyl group represented by R ¹ is 18 or less, the solubility with the refrigerant is kept good, and it is possible to prevent the occurrence of defects such as poor cooling due to precipitation in the refrigeration system. ..

As the glycidyl ether type epoxy compound, in addition to the epoxy compound represented by the formula (1), neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, It is also possible to use sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, polyalkylene glycol diglycidyl ether and the like.

［式（２）中、Ｒ^２はアリール基、炭素数５〜１８のアルキル基、又はアルケニル基を示す。］ As the glycidyl ester type epoxy compound, for example, a compound represented by the following general formula (2) can be used.

[In the formula (2), ^{R 2} is an aryl group, an alkyl group having 5 to 18 carbon atoms, or an alkenyl group. ]

As the glycidyl ester type epoxy compound represented by the formula (2), glycidyl benzoate, glycidyl neodecanoate, glycidyl-2,2-dimethyloctanoate, glycidyl acrylate and glycidyl methacrylate are preferable.

When the alkyl group represented by R ² has 5 or more carbon atoms, the stability of the epoxy compound is ensured, and the epoxy compound is decomposed before reacting with water, fatty acid, and oxidative deterioration product, or the epoxy compounds are polymerized with each other. The occurrence of polymerization can be suppressed, and the desired function can be easily obtained. On the other hand, when the number of carbon atoms of the alkyl group or alkenyl group represented by R ² is 18 or less, the solubility with the refrigerant is kept good, and it is difficult for precipitation to occur in the refrigerator and to cause problems such as poor cooling. You can

The alicyclic epoxy compound is a compound represented by the following general formula (3) having a partial structure in which carbon atoms forming an epoxy group directly form an alicyclic ring.

Examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis(3,4- Epoxycyclohexylmethyl)adipate, exo-2,3-epoxynorbornane, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 2-(7-oxabicyclo[4.1.0]hept-3-yl )-Spiro(1,3-dioxane-5,3′-[7]oxabicyclo[4.1.0]heptane, 4-(1′-methylepoxyethyl)-1,2-epoxy-2-methylcyclohexane , 4-epoxyethyl-1,2-epoxycyclohexane is preferred.

Examples of the allyloxirane compound include 1,2-epoxystyrene and alkyl-1,2-epoxystyrene.

As the alkyloxirane compound, 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxynonane, 1, 2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, 1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1,2-epoxyhexadecane, 1, Examples include 2-epoxyheptadecane, 1,1,2-epoxyoctadecane, 2-epoxynonadecane, and 1,2-epoxyicosane.

Examples of the epoxidized fatty acid monoester include esters of epoxidized fatty acid having 12 to 20 carbon atoms and alcohol having 1 to 8 carbon atoms, or phenol or alkylphenol. As the epoxidized fatty acid monoester, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxystearic acid are preferably used.

Examples of epoxidized vegetable oils include epoxy compounds of vegetable oils such as soybean oil, linseed oil and cottonseed oil.

From the viewpoint of improving the stability of the refrigerating machine oil, the content of the epoxy compound is preferably 0.1 mass% or more, more preferably 0.15 mass% or more, even more preferably 0.2 mass%, based on the total amount of the refrigerating machine oil. That is all. From the viewpoint of improving lubricity, the content of the epoxy compound is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.5% by mass or less, based on the total amount of the refrigerating machine oil. ..

The phosphorus compound (also referred to as “phosphorus additive” or “phosphorus antiwear agent”) is not particularly limited, but may be a phosphoric acid ester, an acidic phosphoric acid ester, a thiophosphoric acid ester, an amine salt of an acidic phosphoric acid ester, Examples thereof include chlorinated phosphoric acid ester and phosphorous acid ester. These phosphorus compounds may be used alone or in combination of two or more.

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, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, etc. Can be mentioned.

Examples of the acidic phosphoric acid ester include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate, and monododecyl. Acid Phosphate, Monotridecyl Acid Phosphate, Monotetradecyl Acid Phosphate, Monopentadecyl Acid Phosphate, Monohexadecyl Acid Phosphate, Monoheptadecyl Acid Phosphate, Monooctadecyl Acid Phosphate, Monooleyl Acid Phosphate, Dibutyl Acid Phosphate, Dipentyl Acid Phosphate , Dihexyl acid phosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl acid phosphate , Dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, and the like.

Thiophosphoric acid esters include tributylphosphorothionate, tripentylphosphorothionate, trihexylphosphorothionate, triheptylphosphorothionate, trioctylphosphorothionate, trinonylphosphorothionate, tridecylphosphoroate. Phorothionate, triundecylphosphorothionate, tridodecylphosphorothionate, tritridecylphosphorothionate, tritetradecylphosphorothionate, tripentadecylphosphorothionate, trihexadecylphosphorothionate, Triheptadecylphosphorothionate, trioctadecylphosphorothionate, trioleylphosphorothionate, triphenylphosphorothionate, tricresylphosphorothionate, trixylenylphosphorothionate, cresyldiphenylphosphoroate Examples thereof include thionate and xylenyldiphenylphosphorothionate.

Examples of the amine salt of acidic phosphoric acid ester include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine of the above-mentioned acidic phosphoric acid ester. , Dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, and salts with amines.

Examples of the chlorinated phosphoric acid ester include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, tris-chlorophenyl phosphate, polyoxyalkylene bis[di(chloroalkyl)]phosphate and the like. Examples of the phosphite include dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl. Phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite Examples thereof include phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite, and the like.

From the viewpoint of improving lubricity, the content of the phosphorus compound is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, based on the total amount of the refrigerating machine oil. .. From the viewpoint of improving the stability of the refrigerating machine oil, the content of the phosphorus compound is preferably 2.4 mass% or less, more preferably 2.0 mass% or less, still more preferably 1.0 mass%, based on the total amount of the refrigerating machine oil. It is the following.

Refrigerating machine oil can also contain additives other than an epoxy compound and a phosphorus compound. Examples of such additives include 2,6-di-tert. -Phenol-based antioxidants such as -butyl-p-cresol and bisphenol A, amine-based antioxidants such as phenyl-α-naphthylamine, N,N-di(2-naphthyl)-p-phenylenediamine, and chlorination Extreme pressure agents such as paraffin and sulfur compounds, oiliness agents such as fatty acids, defoaming agents such as silicones, metal deactivators such as benzotriazole, antiwear agents, viscosity index improvers, pour point depressants, clean dispersion Agents and the like. These additives may be used alone or in combination of two or more. The content of these additives is not particularly limited, but may be, for example, 10% by mass or less and 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. is preferably 2 mm ² /s or more, more preferably 2.3 mm ² /s or more, and further preferably 3 mm ² /s or more from the viewpoint of improving lubricity. The kinematic viscosity of the refrigerating machine oil at 40° C. is preferably 500 mm ² /s or less, more preferably 300 mm ² /s or less, and still more preferably 200 mm ² /s or less, from the viewpoint of improving the oil return property. The kinematic viscosity of the refrigerator oil at 100° C. is preferably 1 mm ² /s or more, more preferably 2 mm ² /s or more, from the viewpoint of improving the stability of the refrigerator oil. The kinematic viscosity of the refrigerating machine oil at 100° C. is preferably 100 mm ² /s or less, more preferably 50 mm ² /s or less, from the viewpoint of improving the oil return property.

The volume resistivity of the refrigerating machine oil can be 1.0×10 ¹² Ω·cm or more, 1.0×10 ¹³ Ω·cm or more, and 1.0×10 ¹⁴ Ω·cm or more. Can be In particular, when refrigerating machine oil is used in a closed refrigerator, it is preferable that the refrigerating machine oil has high electric insulation. The volume resistivity in the present invention means the volume resistivity at 25° C. measured according to JIS C2101:1999.

The water content of the refrigerating machine oil can be preferably 100 ppm or less, more preferably 50 ppm or less, and most preferably 30 ppm or less, based on the total amount of the refrigerating machine oil. In particular, when refrigerating machine oil is used in a closed type refrigerating machine, it is preferable that the refrigerating machine oil has a low water content from the viewpoints of influence on the thermal/chemical stability and electric insulating property.

The acid value of the refrigerating machine oil can be preferably 0.1 mgKOH/g or less, more preferably 0.05 mgKOH/g or less, from the viewpoint of preventing corrosion of the metal used in the refrigerator or piping. The acid value in the present invention means an acid value measured according to JIS K2501:2003.

The ash content of the refrigerating machine oil can be preferably 100 ppm or less, and more preferably 50 ppm or less from the viewpoint of enhancing the thermal and chemical stability of the refrigerating machine oil and suppressing the generation of sludge and the like. The ash content in the present invention means the ash content measured according to JIS K2272:1998.

The pour point of the refrigerating machine oil can be preferably -10°C or lower, and more preferably -20°C or lower. The pour point in the present invention means the pour point measured according to JIS K2268-1987.

The composition containing an alkylbenzene as a base oil according to the present embodiment contains a refrigerating machine oil and a slightly combustible hydrofluorocarbon (HFC) refrigerant as constituent components of a refrigerating machine oil used together with a slightly combustible hydrofluorocarbon (HFC) refrigerant. It is suitably used as a constituent component of the working fluid composition for a refrigerator to be contained.

The alkylbenzene according to the present embodiment is used for producing a refrigerating machine oil used together with a slightly flammable hydrofluorocarbon (HFC) refrigerant, or a working fluid composition for a refrigerator containing a refrigerating machine oil and a slightly flammable hydrofluorocarbon (HFC) refrigerant. It is preferably used.

The refrigerating machine oil of this embodiment is used together with a slightly combustible hydrofluorocarbon (HFC) refrigerant, and the working fluid composition for a refrigerator of this embodiment contains a slightly combustible hydrofluorocarbon (HFC) refrigerant. is there. Hydrofluorocarbon (HFC) refrigerants include saturated fluorohydrocarbon refrigerants (also called hydrofluoroalkane refrigerants) and unsaturated fluorohydrocarbon refrigerants (also called hydrofluoroalkene refrigerants, hydrofluoroolefin refrigerants, or HFO refrigerants). Included. The slightly flammable refrigerant in the present invention means a refrigerant included in the A2L section in the flammability section of ASHRAE (The American Society of Heating, Refrigerating and Air-conditioning Engineers) 34.

Examples of the slightly flammable hydrofluorocarbon refrigerant include difluoromethane (HFC-32), 1,3,3,3-tetrafluoropropene (HFC-1234ze), 2,3,3,3-tetrafluoropropene (HFC-). 1234yf). As the slightly flammable hydrofluorocarbon refrigerant, 1,3,3,3-tetrafluoropropene (HFC-1234ze) or 2,3,3,3-tetrafluoropropene (HFC-1234yf) is preferable.

The refrigerant used with the refrigerating machine oil of the present embodiment may be a mixed refrigerant of a slightly flammable hydrofluorocarbon refrigerant and another refrigerant. Other refrigerants include hydrofluorocarbon refrigerants other than slightly flammable hydrofluorocarbon refrigerants, fluorine-containing ether refrigerants such as perfluoroethers, bis(trifluoromethyl)sulfide refrigerants, trifluoroiodomethane refrigerants, dimethyl ether, and dioxide. Examples include natural refrigerants such as carbon, ammonia and hydrocarbons. As the other refrigerant, a refrigerant made of a compound having no oxygen atom is preferably used.

Examples of hydrofluorocarbon refrigerants other than the slightly flammable hydrofluorocarbon refrigerant include trifluoromethane (HFC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-Tetrafluoroethane (HFC-134a), 1,1,1-Trifluoroethane (HFC-143a), 1,1-Difluoroethane (HFC-152a), Fluoroethane (HFC-161) , 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), 1,1,1 ,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3-pentafluorobutane (HFC -365mfc), 1,2,3,3,3-pentafluoropropene (HFC-1225ye) and the like.

The hydrocarbon refrigerant is preferably a hydrocarbon having 3 to 5 carbon atoms, and specifically, for example, methane, ethylene, ethane, propylene, propane, cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, 2-methylbutane. , Normal pentane or a mixture of two or more thereof. Among them, those which are gaseous at 25° C. and 1 atm are preferably used, and propane, normal butane, isobutane, 2-methyl butane or a mixture thereof is preferable.

Specific examples of the fluorine-containing ether-based refrigerant include HFE-134p, HFE-245mc, HFE-236mf, HFE-236me, HFE-338mcf, HFE-365mcf, HFE-245mf, HFE-347mmy, HFE-347mcc, HFE-125, HFE-143m, HFE-134m, HFE-227me, etc. are mentioned, and these refrigerants are appropriately selected according to the intended use and the required performance.

When the refrigerant is a mixed refrigerant, the mixture ratio (mass ratio, slightly combustible hydrofluorocarbon refrigerant:other refrigerant) of the slightly combustible hydrofluorocarbon refrigerant and the other refrigerant may be 1:99 to 99:1. It can be set to 5:95 to 95:5.

Refrigerating machine oil is usually present in refrigeration and air conditioning equipment in the form of a working fluid composition for refrigerating machines, which is mixed with a slightly flammable hydrofluorocarbon refrigerant alone or with a mixed refrigerant. The mixing ratio of the refrigerating machine oil and the refrigerant in the working fluid composition for a refrigerator may be 1 to 500 parts by mass, or 2 to 400 parts by mass, with respect to 100 parts by mass of the refrigerant.

The refrigerating machine oil and the working fluid composition for a refrigerating machine of the present embodiment are preferably used for an air conditioner having a reciprocating or rotating hermetic compressor, a refrigerator, or an open or hermetic car air conditioner. Further, the refrigerating machine oil and the working fluid composition for a refrigerating machine of the present embodiment are preferably used for a dehumidifier, a water heater, a freezer, a refrigerating/refrigerating warehouse, a vending machine, a showcase, a cooling device for a chemical plant and the like. Further, the refrigerating machine oil and the working fluid composition for a refrigerating machine of the present embodiment are also preferably used for those having a centrifugal compressor.

Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

In each of the examples and comparative examples, a refrigerating machine oil containing alkylbenzene having the properties shown in Tables 1 and 2 as a base oil was prepared. Each property of alkylbenzene was measured according to the following standards.
Kinematic viscosity at 40° C.: JIS K2283:2000
Distillation temperature: ASTM D7213-05
Flash point: JIS K2265-4:2007
Autoignition point: ASTM E659-1978

The following oil return test was performed on each refrigerating machine oil. The results are shown in Tables 1 and 2.
[Oil return test 1]
The apparatus shown in FIG. 3 was used. The refrigerant tank 1 was filled with difluoromethane (R32), and a portion 2a of the copper pipe 2 having a length of 1.5 m and an inner diameter of 0.0036 m that was immersed in the constant temperature bath 5 was filled with 5.0 g of refrigerating machine oil. The temperature of the constant temperature bath 5 was set to −20° C., and R32 was flowed from the refrigerant tank 1 to the oil pan 7 at a flow rate of 0.001 m ^{3 /} min in the copper pipe 2. At this time, the flow rate of R32 is a flow meter 3, the pressure in the copper pipe 2 between the refrigerant tank 1 and the constant temperature tank 5 is a pressure gauge 4, and the pressure in the copper pipe 2 between the constant temperature tank 5 and the oil pan 7 is Was monitored by a pressure gauge 6. Thirty minutes after starting to flow R32, the mass of the refrigerating machine oil accumulated in the oil pan 7 was measured, and the oil return rate was calculated according to the following formula. The case where the oil return rate was 20 mass% or more was evaluated as “good”, and the case where the oil return rate was less than 20 mass% was evaluated as “poor”.
Oil return rate (mass %)=(mass (g)/5.0 (g) of refrigerating machine oil accumulated in the oil receiver)×100

[Oil return test 2]
Except for changing the refrigerant to 2,3,3,3-tetrafluoropropene (HFO-1234yf), the oil return rate was calculated in the same manner as in "Oil return test 1", and "good" or "bad" was calculated. An evaluation was made.

The following abrasion resistance test was performed on each refrigerating machine oil of the examples. The results are shown in Table 3.
[Abrasion resistance test 1]
A high-pressure atmosphere friction tester (a rotary sliding system between a rotating vane material and a fixed disk material) manufactured by Shinko Machinery Co., Ltd., which can create a refrigerant atmosphere similar to that of an actual compressor, was used. The test conditions were: the amount of refrigerating machine oil: 600 ml, test temperature: 100° C., rotation speed: 450 rpm, load load: 60 kgf, test time: 1 hour, SKH-51 as the vane material, and FC250 as the disk material. Using. Difluoromethane (R32) was used as the refrigerant, and the internal pressure of the test container was 1.1 MPa. The wear resistance is "good" when the wear depth of the vane material is less than 10 µm and "bad" when the wear depth of the vane material is 10 µm or more because the wear amount of the disk material is extremely small. evaluated.

[Abrasion resistance test 2]
Except that the refrigerant was changed to 2,3,3,3-tetrafluoropropene (HFO-1234yf), the wear depth of the vane material was measured in the same manner as in “wear resistance test 1”, and the result was “good” or “good”. "Poor" was evaluated.

1... Refrigerant tank, 2... Copper pipe, 3... Flowmeter, 4, 6... Pressure gauge, 5... Constant temperature bath, 7... Oil receiver.

Claims (4)

Have a 250 ° C. or more 5% distillation temperature and 460 ° C. or less and 95% distillation temperature is in flash point is 0.99 ° C. or higher, as the base oil alkylbenzene Ru der autoignition point of 340 ° C. or higher, the refrigerating machine oil Contains 50% by mass or more based on the total amount ,
Used with a slightly flammable hydrofluorocarbon refrigerant contained in the A2L category in the flammability category of ASHRAE34 , the refrigerant being difluoromethane, 1,3,3,3-tetrafluoropropene or 2,3,3,3-tetrafluoropropene. you contain, the refrigerating machine oil. The refrigerating machine oil according to claim 1 and a slightly flammable hydrofluorocarbon refrigerant contained in the A2L classification in the flammability classification of ASHRAE34 , wherein the refrigerant is difluoromethane, 1,3,3,3-tetrafluoropropene or containing 2,3,3,3-tetrafluoropropene, working fluid composition for a refrigerating machine. An application of a composition containing 50% by mass or more of alkylbenzene as a base oil, based on the total amount of refrigerating machine oil, to a refrigerating machine oil or a working fluid composition for a refrigerator,
The alkylbenzene has a 5% distillation temperature of 250° C. or higher and a 95% distillation temperature of 460° C. or lower, a flash point of 150° C. or higher, and a spontaneous ignition point of 340° C. or higher,
The refrigerating machine oil is used together with a slightly flammable hydrofluorocarbon refrigerant contained in the A2L classification in the flammability classification of ASHRAE34 , and the refrigerant is difluoromethane, 1,3,3,3-tetrafluoropropene or 2,3,3,3. Containing 3-tetrafluoropropene,
The refrigerant working fluid composition contains the a refrigerating machine oil, and the slightly combustible hydrofluorocarbon refrigerants, applications. An application of an alkylbenzene for producing a refrigerating machine oil or a working fluid composition for a refrigerating machine,
The alkylbenzene has a 5% distillation temperature of 250° C. or higher and a 95% distillation temperature of 460° C. or lower, a flash point of 150° C. or higher, and a spontaneous ignition point of 340° C. or higher,
The refrigerating machine oil contains the alkylbenzene in an amount of 50% by mass or more based on the total amount of the refrigerating machine oil , and is used together with the slightly flammable hydrofluorocarbon refrigerant contained in the A2L category in the flammability category of ASHRAE34 , and the refrigerant is difluoromethane, 1,3. Containing 3,3,3-tetrafluoropropene or 2,3,3,3-tetrafluoropropene,
The refrigerant working fluid composition contains the a refrigerating machine oil, and the slightly combustible hydrofluorocarbon refrigerants, applications.

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