JP2005248039A - Refrigerator oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator oil which exhibits excellent balance among stability, lubricating properties and compatibility with a refrigerant each at a high level and permits stable operation of refrigerating air-conditioning equipment for a long period of time. <P>SOLUTION: The refrigerator oil comprises a mineral oil having a sulfur content of at most 150 mass ppm, a nitrogen content of at most 50 mass ppm and an aromatic content (%C<SB>A</SB>) of 5-25. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to refrigeration oil used in refrigeration and air conditioning equipment.

Conventionally, refrigerating machine oil based on mineral oil has been widely used in refrigeration and air-conditioning equipment for HCFC (hydrochlorofluorocarbon) refrigerants such as R22 (see, for example, Patent Documents 1 and 2).
JP 55-84879 A JP 56-157487 A

  By the way, the performance of refrigerating machine oil is required to have a low pour point and excellent compatibility with refrigerants at low temperatures. Therefore, a so-called naphthenic mineral oil having a high naphthene content in ndM ring analysis is preferably used because it has a low pour point and good compatibility with a chlorofluorocarbon refrigerant.

  In addition, from the viewpoint of long-term use, a refrigerating machine oil that is excellent in stability such as anti-sludge performance and lubricity is required. For example, in order to improve the stability, a method of increasing the refining degree of the base oil and reducing polar substances such as sulfur can be considered.

  However, according to the knowledge of the present inventors, when the refining degree of the base oil is increased, the aromatic content in the base oil is also reduced, so the compatibility is lowered and the performance as a refrigerating machine oil is impaired. Moreover, when polar substances, such as an aromatic content and sulfur content, reduce, lubrication property will also fall. In addition, in order to improve lubricity, the method of adding a sulfur type additive, a phosphorus type additive, etc. can be considered, However, These additives have a tendency to have high activity and to reduce stability.

  Thus, it is difficult to achieve both stability and lubricity with conventional refrigeration oils. In particular, in order to improve system efficiency in recent years, compressors have increased in output and the discharge temperature tends to increase. For this reason, refrigerating machine oil chemically stable with respect to heat, oxidation, etc. is required. Therefore, it is desired to develop a new refrigerating machine oil that is excellent in stability and lubricity and that is also excellent in compatibility with a refrigerant.

  The present invention has been made in view of such circumstances, and the stability, lubricity and compatibility with the refrigerant are balanced at a high level in a balanced manner, and the refrigeration and air conditioning equipment can be stably operated over a long period of time. An object of the present invention is to provide a refrigerating machine oil that can be used.

In order to solve the above problems, the refrigerating machine oil of the present invention contains a mineral oil having a sulfur content of 150 ppm by mass or less, a nitrogen content of 50 ppm by mass or less, and an aromatic content (% C _A ) of 5 to 25. It is characterized by that.

  In the refrigerating machine oil of the present invention, all of the sulfur content, nitrogen content and aromatic content contained in the mineral oil have a specific content, so that the stability of the refrigerating machine oil, lubricity and compatibility with the refrigerant are all achieved. Since the balance is sufficiently increased, it is possible to stably operate a refrigeration / air-conditioning apparatus using HCFC refrigerant or the like over a long period of time.

  Further, the effect of improving the lubricity by the refrigerating machine oil of the present invention can contribute to the improvement of the energy efficiency of the refrigerating and air-conditioning equipment. . That is, in conventional refrigeration and air-conditioning equipment, improvement of the lubricity of refrigeration oil has not been sufficiently studied, and there are concerns about the adverse effects of the use of wear resistance improvers and oil-based agents. In general, the wear resistance is improved by improving the hard side. On the other hand, according to the refrigerating machine oil of the present invention, the sliding load inside the compressor is sufficiently reduced due to its excellent lubricity, so no improvement on the hardware side such as a compressor or a heat exchanger is performed. Both can improve the energy efficiency of refrigeration and air conditioning equipment. In addition, due to the effect of improving the lubricity according to the present invention, a sliding member with a low material grade, that is, an inexpensive sliding member can be used as the sliding member of the compressor, and the cost reduction of the refrigeration air conditioner can be realized. Become. On the other hand, by combining the refrigerating machine oil of the present invention with a compressor having improved wear resistance, the energy efficiency can be dramatically improved.

  According to the refrigerating machine oil of the present invention, stability, lubricity and compatibility with the refrigerant can be balanced at a high level, and excellent electrical insulation and long-term reliability can be obtained. . Therefore, it is possible to stably operate the refrigeration air conditioner for a long time.

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

(Base oil)
The refrigerating machine oil of the present invention contains a mineral oil having a sulfur content of 150 mass ppm or less, a nitrogen content of 50 mass ppm or less, and an aromatic content (% C _A ) of 5 to 25. Such mineral oil is suitably used as a base oil in the refrigerating machine oil of the present invention.

  Here, the sulfur content in the present invention means a value measured according to JIS K2541. Examples of the sulfur content include carbon disulfide, mercaptan, alkyl sulfide, alkyl disulfide, thiophane, thiophene, and sulfonic acid. About the content of such a sulfur compound, from the viewpoint of affecting stability, it is 150 mass ppm or less, preferably 100 mass ppm or less, more preferably 75 mass ppm or less, and most preferably 50 mass ppm or less. .

  The nitrogen content in the present invention means a value measured according to JIS K 2609 (microcoulometric titration method). Examples of nitrogen contained in crude oil include inorganic ammonia compounds such as ammonia, ammonium sulfide, ammonium carbonate, and ammonium chloride, and heterocyclic compounds such as pyridine, quinoline, and naphthene base. The content of such a nitrogen compound is 50 ppm by mass or less, preferably 30 ppm by mass or less, more preferably 20 ppm by mass or less, and most preferably 15 ppm by mass or less from the viewpoint of affecting stability.

Further, the aromatic content (% C _A ) in the present invention means a value calculated by the ndM method based on ASTM D 3238. This aromatic content (% C _A ) not only greatly affects the compatibility with the refrigerant, which is the basic performance as a base oil for refrigerator oil, but also affects lubricity and stability. For this reason, the aromatic content (% C _A ) is 5 or more, and preferably 8 or more from the viewpoint of affecting the lubricity. On the other hand, the aromatic content (% C _A ) is 25 or less, but is preferably 20 or less, more preferably 15 or less from the viewpoint of affecting the stability and hue stability of the oil.

Moreover, the mineral oil mentioned above may further contain a naphthene content (% C _N ) and a paraffin content (% C _P ), and the naphthene content calculated by the nd-M method in accordance with ASTM D 3238 ( % C _N ) is preferably 30 or more, more preferably 35 or more, and most preferably 40 or more, from the viewpoint of the compatibility of the refrigerant. Further, from the viewpoint of viscosity temperature characteristics, the naphthene content (% C _N ) is preferably 60 or less. On the other hand, the paraffin content (% C _P ) calculated from the ndM method is preferably 60 or less, more preferably 55 or less, from the viewpoint of compatibility. From the viewpoint of lubricity, the paraffin content (% C _P ) is preferably 35 or more, more preferably 40 or more.

  As mineral oils, for example, solvent degreasing, solvent extraction, hydrocracking of lubricating oil fractions obtained by atmospheric distillation and vacuum distillation of paraffinic, intermediate or naphthenic crude oils , Paraffinic mineral oil or naphthenic mineral oil obtained by applying a combination of one or more kinds of purification means such as solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment as appropriate.

  Among these mineral oils, it is preferable to use highly refined mineral oil (hereinafter referred to as “highly refined mineral oil”) from the viewpoint of superior thermal and oxidation stability. Specific examples of highly refined mineral oils include distillate oil obtained by atmospheric distillation of paraffinic crude oil, intermediate crude oil or naphthenic crude oil, or by distilling residual oil of atmospheric distillation under reduced pressure according to a conventional method. Refined oil obtained by refining; deep dewaxed oil obtained by further deep dewaxing after refining; hydrotreated oil obtained by hydrotreating, and the like.

  The purification method in the purification step is not particularly limited, and a conventionally known method can be used. For example, (a) hydrogenation treatment, (b) dewaxing treatment (solvent dewaxing or hydrodehydration). A method of performing any one of wax), (c) solvent extraction treatment, (d) alkali washing or sulfuric acid washing treatment, and (e) clay processing alone or in combination of two or more in an appropriate order. Can be mentioned. It is also effective to repeat any one of the processes (a) to (e) in a plurality of stages. More specifically, (i) a method of hydrotreating distillate oil, or a method of performing alkali washing or sulfuric acid washing treatment after hydrogenation treatment; (ii) dehydrating oil after hydrogenation treatment. A method of wax treatment; (iii) a method of subjecting the distillate to a hydrogenation treatment after solvent extraction; (iv) subjecting the distillate to a two-stage or three-stage hydrotreatment, or subsequent alkali washing or sulfuric acid (V) A method of dewaxing again to obtain a deep dewaxed oil after the above-described treatments (i) to (iv), and the like.

The mineral oil used in the present invention uses, for example, crude oil having a sulfur content of 0.5% by mass or less, a nitrogen content of 0.3% or less, and an aromatic content of 30% or less as a raw material. The lubricating oil fraction obtained by distillation was hydrotreated in the presence of a Co-Mo or Ni-W catalyst under the conditions of a pressure of 100 to 200 Kg / cm ² and a temperature of 300 to 400 ° C, and then furfural was used. It can be obtained by carrying out a solvent purification and then purifying by carrying out a clay treatment after hydrotreating under conditions of a pressure of 100 to 200 Kg / cm ² and a temperature of 300 to 400 ° C.

  The pour point of the mineral oil according to the present invention is preferably 0 ° C. or lower, more preferably −10 ° C. or lower, still more preferably −20 ° C. or lower, and most preferably −30 ° C. or lower. When the pour point of mineral oil exceeds 0 ° C., it may become a solid at room temperature, and it tends to be difficult to handle. In addition, the pour point in this invention means the value measured based on JISK2269.

  Further, the acid value of the mineral oil is preferably 0.05 mgKOH / g or less, more preferably 0.03 mgKOH / g or less. When the acid value of mineral oil exceeds 0.05 mgKOH / g, the stability tends to decrease. In addition, the acid value in this invention means the value measured based on JISK2501.

Furthermore, the upper limit of the kinematic viscosity at 40 ° C. of the mineral oil is preferably 200 mm ² / s, more preferably 100 mm ² / s. On the other hand, the lower limit of the kinematic viscosity is preferably 3 mm ² / s, more preferably 5 mm ² / s. If the kinematic viscosity exceeds the upper limit, the efficiency tends to deteriorate in actual performance, whereas if the kinematic viscosity is less than the lower limit, the wear resistance tends to deteriorate. The kinematic viscosity in the present invention means a value measured according to JIS K 2283.

  Furthermore, the viscosity index of mineral oil is preferably −10 or more, more preferably 0 or more. When the viscosity index of mineral oil is less than −10, the fluidity at low temperatures tends to deteriorate. In addition, the viscosity index in this invention means the value measured based on JISK2283.

  The content of mineral oil in the refrigerating machine oil of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and most preferably 95% by mass based on the total mass of the refrigerating machine oil. %. When the content of mineral oil is less than 70% by mass, characteristics of the base oil such as compatibility and stability tend to be lost.

  The refrigerating machine oil of the present invention contains the above-described mineral oil as a base oil. In addition to this, mineral oil other than the above-described mineral oil, hydrocarbon-based synthetic oil, oxygen-containing synthetic oil, etc. (hereinafter referred to as “other base oil”) May be further contained. However, the content of other base oils is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less from the viewpoint of achieving both high stability and good balance between stability and lubricity. Particularly preferably, it is 5% by mass or less, and most preferably no other base oil is contained.

(Phosphorus additive)
The refrigerating machine oil of the present invention can further contain a phosphorus-based additive in order to further improve its wear resistance. Also, the use of phosphorus-based additives is very effective in that the effect of improving the wear resistance and friction characteristics can be further enhanced by using the oily agent described later.

  The phosphorus additive contained in the refrigerating machine oil of the present invention is selected from phosphoric acid ester, acidic phosphoric acid ester, amine salt of acidic phosphoric acid ester, chlorinated phosphoric acid ester, phosphorous acid ester and phosphorothioate. It is preferable that there is at least one.

  Among the phosphorous additives, phosphoric acid ester, acidic phosphoric acid ester, amine salt of acidic phosphoric acid ester, chlorinated phosphoric acid ester, phosphorous acid ester is phosphoric acid or phosphorous acid and alkanol, polyether type alcohol Or its derivatives.

Phosphate esters 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 .;
Examples of acidic phosphate esters 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, 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 , Dihexyl reed Dophosphate, 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, dipentadecyl acid Hexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, etc .;
Examples of the amine salt of acidic phosphate ester include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, Salts with amines such as dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, etc .;
Examples of the chlorinated phosphate ester include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, tris-chlorophenyl phosphate, polyoxyalkylene bis [di (chloroalkyl)] phosphate, and the like;
As phosphites, 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 Phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite and the like. Mixtures of these can also be used.

［式中、Ｒ^１１〜Ｒ^１３は同一でも異なっていてもよく、それぞれ炭素数１〜２４の炭化水素基を示す］
で表される化合物である。 The phosphorothioate is represented by the following general formula (1):

[Wherein R ^{11 to} R ¹³ may be the same or different and each represents a hydrocarbon group having 1 to 24 carbon atoms]
It is a compound represented by these.

Specific examples of the hydrocarbon group having 1 to 24 carbon atoms represented by R ^{11 to} R ¹³ include an alkyl group, a cycloalkyl group, an alkenyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, and an arylalkyl group. Etc.

  Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. And alkyl groups such as hexadecyl group, heptadecyl group and octadecyl group (these alkyl groups may be linear or branched).

  As a cycloalkyl group, C5-C7 cycloalkyl groups, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, can be mentioned, for example. Examples of the alkylcycloalkyl group include a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, Examples thereof include an alkylcycloalkyl group having 6 to 11 carbon atoms such as a dimethylcycloheptyl group, a methylethylcycloheptyl group, and a diethylcycloheptyl group (the substitution position of the alkyl group with the cycloalkyl group is also arbitrary).

  Examples of the alkenyl group include butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl Alkenyl groups such as groups (these alkenyl groups may be linear or branched, and the position of the double bond is also optional).

  As an aryl group, aryl groups, such as a phenyl group and a naphthyl group, can be mentioned, for example. Examples of the alkylaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, and decylphenyl. Group, an alkylaryl group having 7 to 18 carbon atoms such as undecylphenyl group and dodecylphenyl group (the alkyl group may be linear or branched, and the substitution position on the aryl group is arbitrary). .

  Examples of the arylalkyl group include arylalkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group (these alkyl groups may be linear or branched). May be branched).

Hydrocarbon group of 1 to 24 carbon atoms represented by the ^R 11 ^{to R 13} is an alkyl group, an aryl group, preferably an alkyl aryl group, an alkyl group having 4 to 18 carbon atoms, having 7 to 24 carbon atoms An alkylaryl group and a phenyl group are more preferable.

  Specific examples of the phosphorothioate represented by the general formula (1) include tributyl phosphorothioate, tripentyl phosphorothioate, trihexyl phosphorothionate, triheptyl phosphorothionate, and trioctyl. Phosphorothioate, trinonyl phosphorothionate, tridecyl phosphorothionate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tri Pentadecyl phosphorothioate, trihexadecyl phosphorothionate, triheptadecyl phosphorothionate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, triphenyl Zyl phosphorothioate, trixylenyl phosphorothioate, cresyl diphenyl phosphorothioate, xylenyl diphenyl phosphorothioate, tris (n-propylphenyl) phosphorothioate, tris (isopropylphenyl) phosphoro Thionate, tris (n-butylphenyl) phosphorothionate, tris (isobutylphenyl) phosphorothionate, tris (s-butylphenyl) phosphorothionate, tris (t-butylphenyl) phosphorothionate, Is mentioned. Mixtures of these can also be used.

  When these phosphorus-based additives are blended in the refrigerating machine oil of the present invention, the blending amount is not particularly limited, but is usually based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blended additives), preferably It is desirable to blend the phosphorus compound in such an amount that it is 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and still more preferably 0.01 to 3% by mass.

(Benzotriazole and / or its derivatives)
The refrigerating machine oil of the present invention preferably further contains benzotriazole and / or a derivative thereof. Inclusion of benzotriazole and / or a derivative thereof can further enhance the effect of improving wear resistance and friction characteristics.

Benzotriazole is a compound represented by the following formula (2).

Examples of the benzotriazole derivative include alkylbenzotriazole represented by the following general formula (3), (alkyl) aminoalkylbenzotriazole represented by the general formula (4), and the like.

In the above formula (3), R ²¹ represents a linear or branched alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group, and x is 1 to 3, preferably 1 or 2. Indicates the number of Examples of R ²¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. As the alkylbenzotriazole represented by the formula (3), a compound in which R ²¹ is a methyl group or an ethyl group and x is 1 or 2 is particularly preferable from the viewpoint of excellent antioxidant properties. Examples thereof include triazole (tolyltriazole), dimethylbenzotriazole, ethylbenzotriazole, ethylmethylbenzotriazole, diethylbenzotriazole, and mixtures thereof.

In the above formula (4), R ³¹ represents a linear or branched alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group, R ³² represents a methylene group or an ethylene group, and R ³³ And R ³⁴ may be the same or different and each represents a hydrogen atom or a linear or branched alkyl group having 1 to 18 carbon atoms, preferably a linear or branched alkyl group having 1 to 12 carbon atoms. And y represents a number of 0 to 3, preferably 0 or 1. Examples of R ³¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. As R ³³ and R ³⁴ , for example, a hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, straight chain or A branched pentyl group, a linear or branched hexyl group, a linear or branched heptyl group, a linear or branched octyl group, a linear or branched nonyl group, a linear or branched decyl group, Linear or branched undecyl group, linear or branched dodecyl group, linear or branched tridecyl group, linear or branched tetradecyl group, linear or branched pentadecyl group, linear or branched Alkyl groups such as a hexadecyl group, a linear or branched heptadecyl group, and a linear or branched octadecyl group.

As the (alkyl) aminobenzotriazole represented by the above formula (4), R ³¹ is a methyl group, y is 0 or 1, and R ³² is a methylene group or from the viewpoint of particularly excellent antioxidant properties. Dialkylaminoalkylbenzotriazole, dialkylaminoalkyltolyltriazole or a mixture thereof, which is an ethylene group and R ³³ and R ³⁴ are linear or branched alkyl groups having 1 to 12 carbon atoms, are preferably used. Examples of these dialkylaminoalkylbenzotriazoles include dimethylaminomethylbenzotriazole, diethylaminomethylbenzotriazole, di (linear or branched) propylaminomethylbenzotriazole, and di (linear or branched) butylaminomethylbenzotriazole. , Di (straight or branched) pentylaminomethylbenzotriazole, di (straight or branched) hexylaminomethylbenzotriazole, di (straight or branched) heptylaminomethylbenzotriazole, di (straight or branched) ) Octylaminomethylbenzotriazole, di (straight or branched) nonylaminomethylbenzotriazole, di (straight or branched) decylaminomethylbenzotriazole, di (straight or branched) undecylaminomethylbenzotriazole, (Linear or branched) dodecylaminomethylbenzotriazole; dimethylaminoethylbenzotriazole, diethylaminoethylbenzotriazole, di (linear or branched) propylaminoethylbenzotriazole, di (linear or branched) butylaminoethylbenzo Triazole, di (straight or branched) pentylaminoethylbenzotriazole, di (straight or branched) hexylaminoethylbenzotriazole, di (straight or branched) heptylaminoethylbenzotriazole, di (straight or branched) Branch) Octylaminoethylbenzotriazole, Di (straight or branched) nonylaminoethylbenzotriazole, Di (straight or branched) decylaminoethylbenzotriazole, Di (straight or branched) undecylaminoethylbenzotriazole , Di (linear or straight Branched) dodecylaminoethyl benzotriazole; dimethylaminomethyltolyltriazole, diethylaminomethyltolyltriazole, di (linear or branched) propylaminomethyltolyltriazole, di (straight or branched) butylaminomethyltolyltriazole, di ( Linear or branched) pentylaminomethyltolyltriazole, di (linear or branched) hexylaminomethyltolyltriazole, di (straight or branched) heptylaminomethyltolyltriazole, di (linear or branched) octylamino Methyltolyltriazole, di (linear or branched) nonylaminomethyltolyltriazole, di (straight or branched) decylaminomethyltolyltriazole, di (straight or branched) undecylaminomethyltolyltriazole, di (direct Chain or branch) Silaminomethyltolyltriazole; dimethylaminoethyltolyltriazole, diethylaminoethyltolyltriazole, di (linear or branched) propylaminoethyltolyltriazole, di (linear or branched) butylaminoethyltolyltriazole, di (linear or Branched) pentylaminoethyltolyltriazole, di (straight or branched) hexylaminoethyltolyltriazole, di (straight or branched) heptylaminoethyltolyltriazole, di (straight or branched) octylaminoethyltolyltriazole , Di (linear or branched) nonylaminoethyl tolyl triazole, di (linear or branched) decylaminoethyl tolyl triazole, di (linear or branched) undecylaminoethyl tolyl triazole, di (linear or branched) Branch) Dodecylamino Tilt Lil triazole; or mixtures thereof.

  The content of benzotriazole and / or a derivative thereof in the refrigerating machine oil of the present invention is arbitrary, but is preferably 0.001% by mass or more, more preferably 0.005% by mass or more based on the total amount of the refrigerating machine oil. When the amount is less than 0.001% by mass, the effect of improving wear resistance and frictional properties due to the inclusion of benzotriazole and / or its derivatives may be insufficient. Further, the content of benzotriazole and / or a derivative thereof is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, based on the total amount of refrigerating machine oil. If it exceeds 1.0% by mass, the effect of improving the wear resistance and frictional properties corresponding to the content cannot be obtained, which may be economically disadvantageous.

(Epoxy compound)
In the refrigerating machine oil of the present invention, in order to further improve the stability and lubricity,
(1) Phenyl glycidyl ether type epoxy compound (2) Alkyl glycidyl ether type epoxy compound (3) Glycidyl ester type epoxy compound (4) Allyl oxirane compound (5) Alkyl oxirane compound (6) Alicyclic epoxy compound (7) Epoxy It is preferable to blend at least one epoxy compound selected from the group consisting of epoxidized fatty acid monoester (8) epoxidized vegetable oil.

  (1) Specific examples of the phenyl glycidyl ether type epoxy compound include phenyl glycidyl ether and alkylphenyl glycidyl ether. As used herein, the alkylphenyl glycidyl ether includes those having 1 to 3 alkyl groups having 1 to 13 carbon atoms, and those having one alkyl group having 4 to 10 carbon atoms, such as n-butylphenyl glycidyl. Ether, i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether, hexylphenyl glycidyl ether, heptylphenyl glycidyl ether, octylphenyl glycidyl ether, nonylphenyl glycidyl ether, decylphenyl A glycidyl ether etc. can be illustrated as a preferable thing.

  (2) Specific examples of the alkyl glycidyl ether type epoxy compound include decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl glycidyl ether, neopentyl glycol di Examples thereof include glycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, polyalkylene glycol diglycidyl ether and the like.

［式中、Ｒ^４１は炭素数１〜１８の炭化水素基を表す］
で表される化合物が挙げられる。 (3) As the glycidyl ester type epoxy compound, specifically, the following general formula (5):

[Wherein R ⁴¹ represents a hydrocarbon group having 1 to 18 carbon atoms]
The compound represented by these is mentioned.

In the above formula ^{(5), R 41} is a hydrocarbon group having 1 to 18 carbon atoms, examples of such hydrocarbon groups include alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, C5-C7 cycloalkyl group, C6-C18 alkylcycloalkyl group, C6-C10 aryl group, C7-C18 alkylaryl group, C7-C18 arylalkyl group, etc. Is mentioned. Among these, an alkylphenyl group having an alkyl group having 5 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, a phenyl group, and an alkyl group having 1 to 4 carbon atoms is preferable.

  Specific examples of glycidyl ester type epoxy compounds include glycidyl-2,2-dimethyloctanoate, glycidyl benzoate, glycidyl-tert-butyl benzoate, glycidyl acrylate, and glycidyl methacrylate.

  (4) Specific examples of the allyloxirane compound include 1,2-epoxystyrene, alkyl-1,2-epoxystyrene, and the like.

  (5) Specific examples of the alkyloxirane compound include 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, 2,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,1,2-epoxyoctadecane, 2-epoxynonadecane, 1,2-epoxyicosane and the like.

で表される化合物のように、エポキシ基を構成する炭素原子が直接脂環式環を構成している化合物が挙げられる。 (6) As an alicyclic epoxy compound, the following general formula (6):

And a compound in which the carbon atom constituting the epoxy group directly constitutes an alicyclic ring.

  Specific examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 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-methyl Examples include cyclohexane and 4-epoxyethyl-1,2-epoxycyclohexane.

  (7) Specific examples of the epoxidized fatty acid monoester include esters of an epoxidized fatty acid having 12 to 20 carbon atoms with an alcohol or phenol having 1 to 8 carbon atoms or an alkylphenol. In particular, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxy stearate are preferably used.

  (8) Specific examples of epoxidized vegetable oils include epoxy compounds of vegetable oils such as soybean oil, linseed oil, and cottonseed oil.

  Among these epoxy compounds, phenyl glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, alicyclic epoxy compounds, and epoxidized fatty acid monoesters are preferred because glycidyl esters can improve stability and lubricity. Type epoxy compounds and alicyclic epoxy compounds are more preferred.

  When these epoxy compounds are blended in the refrigerating machine oil of the present invention, the blending amount is not particularly limited, but usually the content is 0 based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blended additives). It is desirable to mix the epoxy compound in such an amount that it is 1 to 5.0% by mass, more preferably 0.2 to 2.0% by mass.

  Of course, two or more of the above phosphorus compounds and epoxy compounds may be used in combination.

(Oil-based agent)
The refrigerator oil of the present invention can further contain an oily agent. Examples of oil agents include ester oil agents, monohydric alcohol oil agents, carboxylic acid oil agents, ether oil agents, and the like.

  The ester oily agent is obtained by reacting an alcohol and a carboxylic acid. The alcohol may be a monohydric alcohol or a polyhydric alcohol. The carboxylic acid may be a monobasic acid or a polybasic acid.

  As a monohydric alcohol which comprises an ester oily agent, C1-C24 normally, Preferably it is 1-12, More preferably, the thing of 1-8 is used. Such alcohols may be linear or branched, and may be saturated or unsaturated.

  Moreover, as a polyhydric alcohol which comprises ester oiliness agent, a 2-10 valence is used normally, Preferably a 2-6 valence is used.

  Of the acids constituting the ester oily agent, as the monobasic acid, a fatty acid having 2 to 24 carbon atoms is usually used. The fatty acid may be linear or branched, and may not be saturated. It may be saturated.

  Examples of the polybasic acid include dibasic acid and trimellitic acid, and dibasic acid is preferable from the viewpoint of precipitation prevention in a refrigerant atmosphere and at a low temperature. The dibasic acid may be a chain dibasic acid or a cyclic dibasic acid. Further, in the case of a chain dibasic acid, it may be either linear or branched, and may be either saturated or unsaturated.

  The number of carbon atoms of the monohydric alcohol oil-based agent is preferably 6 or more, more preferably 8 or more, and most preferably 10 or more, from the viewpoint of improving frictional characteristics and wear characteristics. Moreover, since there exists a possibility that it may become easy to precipitate in a refrigerant | coolant atmosphere when carbon number is too large, carbon number becomes like this. Preferably it is 20 or less, More preferably, it is 18 or less, Most preferably, it is 16 or less.

  The carboxylic acid oily agent may be a monobasic acid or a polybasic acid. Such carbon number of carboxylic acid is preferably 6 or more, more preferably 8 or more, and most preferably 10 or more, from the viewpoint of improving frictional characteristics and wear characteristics. Moreover, since there exists a possibility that it may precipitate easily in a refrigerant | coolant atmosphere if carbon number of a carboxylic acid oiliness agent is too large, carbon number becomes like this. Preferably it is 20 or less, More preferably, it is 18 or less, Most preferably, it is 16 or less.

  Examples of ether oily agents include etherified products of 3 to 6 aliphatic polyhydric alcohols, bimolecular condensates or trimolecular condensates of 3 to 6 aliphatic polyhydric alcohols, and the like.

  Although the content of the oily agent is arbitrary, it is preferably 0.01% by mass or more based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blended additives) from the viewpoint of excellent lubricity improvement effect. More preferably, it is 0.05 mass% or more, More preferably, it is 0.1 mass% or more. Further, the content is preferably 10% by mass or less, more preferably 7.5% on the basis of the total amount of the refrigerating machine oil, from the viewpoint of excellent precipitation prevention under a refrigerant atmosphere and low temperature and the stability of the refrigerating machine oil. It is at most 5% by mass, more preferably at most 5% by mass.

(Other additives)
Furthermore, in order to further improve the performance of the refrigerating machine oil in the present invention, conventionally known refrigerating machine oil additives, for example, phenol-based oxidation such as di-tert-butyl-p-cresol, bisphenol A, etc. Antioxidants, amine-based antioxidants such as phenyl-α-naphthylamine, N, N-di (2-naphthyl) -p-phenylenediamine, antiwear agents such as zinc dithiophosphate, chlorinated paraffin, sulfur compounds, etc. It is also possible to add an additive such as an extreme pressure agent, an oily agent such as a fatty acid, a silicone-based antifoaming agent, a viscosity index improver, a pour point depressant, a cleaning dispersant, etc. alone or in combination. . The total blending amount of these additives is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blending additives).

The volume resistivity of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 1.0 × 10 ¹³ Ω · cm or more. In particular, high electrical insulation tends to be required when used in a closed refrigerator. Here, the volume resistivity means a value [Ω · cm] at 25 ° C. measured in accordance with JIS C 2101 “Electrical Insulating Oil Test Method”.

  Furthermore, the water content of the refrigerating machine oil of the present invention is not particularly limited, but can be preferably 100 ppm by mass or less, more preferably 75 ppm by mass or less, and most preferably 50 ppm by mass or less based on the total amount of refrigerating machine oil. In particular, when used for a closed type refrigerator, the water content is required to be low from the viewpoint of the influence on the heat and hydrolysis stability of oil and electrical insulation.

  Furthermore, the acid value of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 0.1 mgKOH / g or less, more preferably 0.05 mgKOH, in order to prevent corrosion to the metal used in the refrigerating machine or piping. / G or less. The acid value here means a value [mg KOH / g] measured in accordance with JIS K 2501 “Petroleum products and lubricating oil-neutralization number test method”.

  Furthermore, although the ash content of the refrigerating machine oil of the present invention is not particularly limited, it is preferably 100 ppm by mass or less, more preferably 50 mass% in order to increase the heat / hydrolysis stability of the refrigerating machine oil of the present invention and suppress the generation of sludge and the like. It can be made into mass ppm or less. In the present invention, the ash means a value [mass ppm] measured in accordance with JIS K 2272 “Testing method for ash and sulfated ash of crude oil and petroleum products”.

  Furthermore, the pour point of the refrigerating machine oil of the present invention is preferably 0 ° C. or lower, more preferably −10 ° C. or lower, still more preferably −20 ° C. or lower, and most preferably −30 ° C. or lower. When the pour point of the refrigerating machine oil exceeds 0 ° C., it may become a solid at room temperature, which tends to be difficult to handle.

Furthermore, the upper limit of the kinematic viscosity at 40 ° C. of the refrigerating machine oil of the present invention is preferably 200 mm ² / s, more preferably 100 mm ² / s. On the other hand, the lower limit of the pour point of the refrigerator is preferably 3 mm ² / s, more preferably 5 mm ² / s. If the kinematic viscosity exceeds the upper limit, the efficiency tends to deteriorate in actual performance, whereas if the kinematic viscosity is less than the lower limit, the wear resistance tends to deteriorate.

  Furthermore, the viscosity index of the refrigerating machine oil of the present invention is preferably −10 or more, more preferably 0 or more. When the viscosity index is less than −10, the fluidity at low temperatures tends to deteriorate.

  The refrigerant used in the refrigerating and air-conditioning equipment using the refrigerating machine oil of the present invention includes CFC refrigerant, HCFC refrigerant, HFC refrigerant, fluorine-containing ether refrigerant such as perfluoroethers, non-fluorine-containing ether refrigerant such as dimethyl ether, carbon dioxide, Natural refrigerants such as ammonia and hydrocarbons may be used alone or in a mixture of two or more.

  Examples of the CFC refrigerant include chlorofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms. Specifically, trichloromonofluoromethane (R12), dichlorodifluoromethane (R12), monochlorotrifluoromethane (R13), tetrafluoromethane (R14), tetrachlorodifluoroethane (R112), trichlorotrifluoroethane (R113), dichloro And tetrafluoroethane (R114) and monochloropentafluoroethane (R115). Examples of HCFCs include monochlorodifluoromethane (R22) and monochlorodifluoroethane (R142b). The HCFC refrigerant includes hydrochlorofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms. Examples of the HFC refrigerant include hydrofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms. Specifically, for example, difluoromethane (HFC-32), trifluoromethane (HFC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1, HFC such as 1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), or two or more of these And the like. These refrigerants are appropriately selected depending on the application and required performance. For example, HFC-32 alone; HFC-23 alone; HFC-134a alone; HFC-125 alone; HFC-134a / HFC-32 = 60 to 80 mass % / 40-20 mass% mixture; HFC-32 / HFC-125 = 40-70 mass% / 60-30 mass% mixture; HFC-125 / HFC-143a = 40-60 mass% / 60-40 mass % Mixture; HFC-134a / HFC-32 / HFC-125 = 60 wt% / 30 wt% / 10 wt% mixture; HFC-134a / HFC-32 / HFC-125 = 40-70 wt% / 15- 35 mass% / 5 to 40 mass% mixture; HFC-125 / HFC-134a / HFC-143a = 35-55 mass% / 1-15 mass% / 40-60 mass Mixtures of preferred examples include. More specifically, a mixture of HFC-134a / HFC-32 = 70/30 mass%; a mixture of HFC-32 / HFC-125 = 60/40 mass%; HFC-32 / HFC-125 = 50/50 mass % Mixture (R410A); HFC-32 / HFC-125 = 45/55 wt% mixture (R410B); HFC-125 / HFC-143a = 50/50 wt% mixture (R507C); HFC-32 / HFC -125 / HFC-134a = 30/10/60 wt% mixture; HFC-32 / HFC-125 / HFC-134a = 23/25/52 wt% mixture (R407C); HFC-32 / HFC-125 / HFC-134a = 25/15/60 mass% mixture (R407E); HFC-125 / HFC-134a / HFC-143a = Mixtures of 4/4/52 wt% (R404A), and the like.

  Examples of natural refrigerants include carbon dioxide, ammonia, and hydrocarbons. Here, as the hydrocarbon refrigerant, a gas refrigerant at 25 ° C. and 1 atm is preferably used. Specifically, it is an alkane, cycloalkane, alkene or a mixture thereof having 1 to 5 carbon atoms, preferably 1 to 4 carbon atoms. Specific examples include methane, ethylene, ethane, propylene, propane, cyclopropane, butane, isobutane, cyclobutane, methylcyclopropane, or a mixture of two or more thereof. Among these, propane, butane, isobutane or a mixture thereof is preferable.

  The refrigerating machine oil of the present invention is usually present in the form of a refrigerating machine fluid composition mixed with the refrigerant as described above in the refrigerating and air-conditioning equipment. The blending ratio of the refrigerating machine oil and the refrigerant in this fluid composition is not particularly limited, but the refrigerating machine oil is preferably 1 to 500 parts by weight, more preferably 2 to 400 parts by weight with respect to 100 parts by weight of the refrigerant.

  The refrigerating machine oil of the present invention sufficiently satisfies all the required performance such as lubricity, refrigerant compatibility, low-temperature fluidity, stability and the like, and is a reciprocating or rotating open type or semi-sealed type or It can be suitably used for a refrigeration apparatus having a hermetic compressor or a heat pump. In particular, when it is used in a refrigeration apparatus using an aluminum-based member, it is possible to achieve both high wear resistance and thermal / chemical stability of the aluminum-based member at a high level. More specifically, as such refrigeration equipment, automotive air conditioners, dehumidifiers, refrigerators, refrigerator / freezer warehouses, vending machines, showcases, cooling equipment for chemical plants, residential air conditioners, air conditioners for building air conditioning, heat pumps for hot water supply, etc. Etc. Furthermore, the refrigerating machine oil of the present invention can be used in any type of compressor such as a reciprocating type, a rotary type, and a centrifugal type.

  As a configuration of a refrigerant circulation system in which the refrigerating machine oil of the present invention can be suitably used, typically, a refrigerant compressor, a condenser, an expansion mechanism, and an evaporator are connected in this order via respective flow paths. Examples of those equipped with a dryer in the flow path as necessary

  As a refrigerant compressor, a motor composed of a rotor and a stator in a sealed container for storing refrigerating machine oil, a rotating shaft fitted to the rotor, and a compressor connected to the motor via the rotating shaft A high-pressure container type compressor in which high-pressure refrigerant gas discharged from the compressor unit stays in a sealed container, a motor composed of a rotor and a stator in a sealed container storing refrigerating machine oil, and rotation A low pressure in which a rotating shaft fitted to the child and a compressor unit connected to the motor via the rotating shaft are housed and high-pressure refrigerant gas discharged from the compressor unit is directly discharged out of the sealed container Examples thereof include a container type compressor.

  As an insulating film which is an electric insulation system material of a motor part, a crystalline plastic film having a glass transition point of 50 ° C. or more, specifically, for example, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ether ketone, polyethylene naphthalate, Polyamideimide, at least one insulating film selected from the group of polyimides, or a composite film in which a resin layer having a high glass transition temperature is coated on a film having a low glass transition temperature is less likely to cause deterioration of tensile strength characteristics and electrical insulation characteristics. Are preferably used. In addition, as a magnet wire used in the motor unit, an enamel coating having a glass transition temperature of 120 ° C. or higher, for example, a single layer such as polyester, polyesterimide, polyamide and polyamideimide, or a layer having a low glass transition temperature as a lower layer, Those having an enamel coating in which a high layer is composite-coated on the upper layer are preferably used. Examples of the composite enameled wire include polyester imide as a lower layer and polyamide imide as an upper layer (AI / EI), polyester as a lower layer and polyamide imide as an upper layer (AI / PE), and the like. .

  As the desiccant to be filled in the dryer, silicic acid and alkali metal aluminate composite salt having a pore diameter of 3.3 angstroms or less and a carbon dioxide absorption capacity at 25 ° C. carbon dioxide partial pressure of 250 mmHg is 1.0% or less. The synthetic zeolite is preferably used. Specifically, trade names XH-9, XH-10, XH-11, XH-600 manufactured by Union Showa Co., Ltd., and the like can be given.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Examples 1-2, Comparative Examples 1-3]
In Examples 1-2 and Comparative Examples 1-3, refrigeration oils composed of the following base oils were used.

(Base oil)
Base oil 1: sulfur content: 48 mass ppm, nitrogen content: 15 mass ppm, aromatic content (% C _A ): 11, kinematic viscosity at 40 ° C .: 56.1 mm ² / s)
Base oil 2: sulfur content: 15 mass ppm, nitrogen content: 10 mass ppm, aromatic content (% C _A ): 12, kinematic viscosity at 40 ° C .: 55.5 mm ² / s)
Base oil 3: sulfur content: 200 mass ppm, nitrogen content: 8 mass ppm, aromatic content (% C _A ): 8, kinematic viscosity at 40 ° C .: 52.8 mm ² / s)
Base oil 4: Sulfur content: 25 mass ppm, nitrogen content: 62 mass ppm, aromatic content (% C _A ): 8, kinematic viscosity at 40 ° C .: 55.3 mm ² / s)
Base oil 5: sulfur content: 20 mass ppm, nitrogen content: 8 mass ppm, aromatic content (% C _A ): 30, kinematic viscosity at 40 ° C .: 56.5 mm ² / s)

  Next, the following evaluation tests were performed on the refrigeration machine oils of Examples 1-2 and Comparative Examples 1-3.

(Evaluation of stability)
In accordance with JIS K 2211, a shield glass tube test was performed using iron, copper and aluminum as a catalyst, and the presence or absence of sludge and a change in the appearance of the catalyst were observed after holding at 200 ° C. for 2 weeks. The refrigerant used was R22. The obtained results are shown in Table 1. In the column of “sludge” in Table 1, A means that no sludge was recognized, and B means that sludge was recognized. In the column of “Catalyst change” in Table 1, A indicates that no change in the catalyst is observed, B indicates that a slight change in the catalyst is observed, and C indicates that the appearance of the catalyst has changed significantly. Each means.

  Moreover, the hue change of oil was evaluated based on ASTM D 1500. In addition, the evaluation standard of the hue change was accepted up to L2.0, and L2.5 or higher was rejected.

(Evaluation of wear resistance)
The sliding part of the FALEEX testing machine (ASTM D2714) was installed in a pressure-resistant container, R22 refrigerant was introduced into the container, and the FALEEX test was performed under the following conditions.
Test start temperature: 80 ° C
Test time: 30 minutes Refrigerant blow amount: 10 L / h

  The weight of the block before and after the end of the FALEX test was measured, and the amount of wear was determined as the weight reduction. The obtained results are shown in Table 1.

(Compatibility)
The compatibility was evaluated according to JIS K 2211 Annex 3. 10 g of sample oil and 40 g of R22 refrigerant were weighed into a 100 ml pressure test tube. Next, the sample was heated in a 30 ° C. hot water bath to make the sample oil and the refrigerant uniform. Next, the test tube was cooled at 1 ° C./min, and the temperature at which the solution separated into two layers or the whole solution became milky was measured to evaluate the compatibility. The obtained results are shown in Table 1.

Claims (1)

_A refrigerating machine oil comprising a mineral oil having a sulfur content of 150 mass ppm or less, a nitrogen content of 50 mass ppm or less, and an aromatic content (% C _A ) of 5 to 25.