JP6216747B2 - Refrigerator oil and working fluid composition for refrigerator - Google Patents

Description

  The present invention relates to refrigeration oil and a working fluid composition for a refrigeration machine, and more particularly, a refrigeration oil useful when used with a difluoromethane refrigerant (HFC-32), and a working fluid composition for a refrigeration machine using the refrigeration oil. Related to things.

  Due to the problem of ozone layer destruction in recent years, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon), which have been used as refrigerants in conventional refrigeration equipment, are subject to regulation, and HFC (hydrofluorocarbon) is used as a refrigerant instead. It is being done.

  When CFC or HCFC is used as a refrigerant, mineral oil or hydrocarbon oil such as alkylbenzene has been suitably used as the refrigeration oil. However, when the refrigerant is changed, the refrigeration oil used in the coexistence is compatible with the refrigerant, Refrigerating machine oil needs to be developed for each refrigerant in order to exhibit unpredictable behaviors such as lubricity, melt viscosity with refrigerant, and thermal and chemical stability. Therefore, as a refrigerating machine oil for HFC refrigerant, for example, polyalkylene glycol (see Patent Document 1), ester (see Patent Document 2), carbonate (see Patent Document 3), polyvinyl ether (see Patent Document 4) Etc. are being developed. Among these refrigerating machine oils, esters are widely used for refrigerators and air conditioners.

  Among HFC refrigerants, HFC-134a, R407C, and R410A are standardly used as refrigerants for car air conditioners, refrigerators, and room air conditioners. However, these HFC refrigerants are becoming subject to regulation because of their high global warming potential (GWP) although their ozone depletion potential (ODP) is zero. Therefore, there is an urgent need to develop refrigerants that can replace these HFCs.

  Under such a background, as a refrigerant that replaces the HFC, both ODP and GWP are very small, non-flammable, and thermodynamic properties that are a measure of refrigerant performance are almost equivalent to the HFC. The use of fluoropropene refrigerants has been proposed. Furthermore, the use of a mixed refrigerant of fluoropropene and saturated hydrofluorocarbon, saturated hydrocarbon having 3 to 5 carbon atoms, dimethyl ether, carbon dioxide, bis (trifluoromethyl) sulfide or trifluoroiodomethane is also proposed ( (See Patent Document 5). In addition, difluoromethane refrigerant (HFC-32) is attracting attention because of its relatively low global warming potential and high refrigeration efficiency among HFC refrigerants.

  By the way, in the refrigerant circulation cycle of the refrigeration equipment, since the refrigeration oil that lubricates the refrigerant compressor normally circulates in the cycle together with the refrigerant, the refrigeration oil is required to have compatibility with the refrigerant. However, if the refrigerating machine oil conventionally used for HFC refrigerant is used together with the difluoromethane refrigerant, sufficient compatibility between the refrigerant and the refrigerating machine oil cannot be obtained, and the refrigerating machine oil discharged from the refrigerant compressor stays in the cycle. As a result, the amount of refrigerating machine oil in the refrigerant compressor decreases, causing problems such as poor lubrication and closing of expansion mechanisms such as capillaries.

  Thus, in order to avoid such a phenomenon, development of a refrigerating machine oil for difluoromethane refrigerant has been advanced, and for example, ester refrigerating machine oils disclosed in Patent Documents 6 to 12 have been proposed.

Japanese Patent Laid-Open No. 02-242888 Japanese Patent Laid-Open No. 03-200895 Japanese Patent Laid-Open No. 03-217495 Japanese Patent Laid-Open No. 06-128578 International Publication WO2006 / 094303 Pamphlet JP-A-6-17073 JP-A-10-298572 JP 2002-060771 A JP 2002-105471 A JP 2002-129177 A JP 2002-129178 A JP 2002-129179 A

  However, even when the conventional ester refrigerating machine oil is used, it is very difficult to achieve both compatibility with the difluoromethane refrigerant and lubricity in the presence of the difluoromethane refrigerant. For example, a conventional ester refrigerating machine oil that exhibits good compatibility with a difluoromethane refrigerant tends to have insufficient lubricity in the presence of the difluoromethane refrigerant. Viscosity (kinematic viscosity, etc.) can be cited as an influencing factor of lubricity, but the problem with lubricity in the presence of difluoromethane refrigerant is a mixture of refrigerating machine oil and difluoromethane refrigerant (that is, working fluid composition). Its viscosity is not easy to control. Furthermore, the lubricity cannot be sufficiently improved only by adjusting the viscosity, regardless of whether the object of viscosity control is the refrigeration oil or the working fluid composition.

  Furthermore, the usage environment of the refrigerating machine oil in the refrigerant circulation cycle extends over a wide temperature range from a high temperature to a low temperature, and the existence ratio of the refrigerating machine oil and the difluoromethane refrigerant greatly varies depending on the position of the refrigerant circulation cycle. However, conventional ester refrigerating machine oils are not always sufficiently compatible with such usage environments. In particular, many of them have insufficient low-temperature fluidity, and this problem is remarkable in the case of esters disclosed in Patent Documents 10 and 11.

  The present invention has been made in view of the above-described problems of the prior art. When used together with a difluoromethane refrigerant, the refrigeration capable of achieving all of refrigerant compatibility, lubricity and low-temperature fluidity at a high level. It is an object of the present invention to provide machine oil and a working fluid composition for a refrigerator using the same.

  In order to solve the above-mentioned problems, the present invention provides an ester of dipentaerythritol and a fatty acid, wherein an ester in which the ratio of 2-methylpentanoic acid in the fatty acid is 20 mol% or more is 10 based on the total amount of refrigerating machine oil. Provided is a refrigerating machine oil containing at least mass% and used with a difluoromethane refrigerant.

  Moreover, this invention provides the working fluid composition for refrigerators containing the refrigerating machine oil of the said invention, and a difluoromethane refrigerant | coolant.

  According to the present invention, when used with a difluoromethane refrigerant, a refrigerating machine oil capable of achieving all of refrigerant compatibility, lubricity and low temperature fluidity at a high level, and a working fluid for a refrigerating machine using the refrigerating machine oil A composition is provided.

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

  The refrigerating machine oil for difluoromethane refrigerant according to the present embodiment is an ester of dipentaerythritol and a fatty acid, and an ester in which the ratio of 2-methylpentanoic acid in the fatty acid is 20 mol% or more, based on the total amount of the refrigerating machine oil. Contains 10% by mass or more. Moreover, the working fluid composition for refrigerators according to this embodiment contains the refrigerator oil according to this embodiment and a difluoromethane refrigerant.

  The content of an ester of dipentaerythritol and a fatty acid (hereinafter sometimes referred to as “dipentaerythritol fatty acid ester”) is 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass based on the total amount of the refrigerating machine oil. More preferably, the content is 30% by mass or more. The refrigerating machine oil for difluoromethane refrigerant according to the present embodiment may contain a base oil and additives other than dipentaerythritol fatty acid ester as described later, but the content of dipentaerythritol fatty acid ester is less than 10% by mass. In this case, compatibility with difluoromethane refrigerant, lubricity in the presence of difluoromethane refrigerant, and low-temperature fluidity cannot be achieved at a high level, and in particular, compatibility and lubricity can be compatible. It becomes very difficult.

  The dipentaerythritol fatty acid ester according to this embodiment includes a complete ester obtained by esterifying all the hydroxyl groups of dipentaerythritol and a partial ester in which a part of the hydroxyl groups of dipentaerythritol remains without being esterified. And a mixture of a complete ester and a partial ester, but the dipentaerythritol fatty acid ester is preferably a complete ester.

  In the fatty acid constituting the dipentaerythritol fatty acid ester, the proportion of 2-methylpentanoic acid is 20 mol% or more, preferably 25 mol% or more, more preferably 30 mol% or more. When the ratio of 2-methylpentanoic acid is less than the lower limit, compatibility with the difluoromethane refrigerant, lubricity in the presence of the difluoromethane refrigerant, and low temperature fluidity cannot be achieved at a high level, In particular, it becomes very difficult to achieve both compatibility and lubricity. In addition, the ratio of 2-methylpentanoic acid as referred to in the present invention is a value based on the total amount of fatty acids constituting dipentaerythritol fatty acid ester contained in the refrigerating machine oil.

  The dipentaerythritol fatty acid ester according to this embodiment may contain a fatty acid other than 2-methylpentanoic acid as a constituent acid component as long as it contains 20 mol% or more of 2-methylpentanoic acid.

  Specific examples of fatty acids other than 2-methylpentanoic acid include acetic acid, propionic acid, butanoic acid, 2-methylpropionic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, and 2,2-dimethylpropanoic acid. , Hexanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutanoic acid, 2,3-dimethylbutanoic acid, 2,4-dimethylbutanoic acid, 3,3-dimethylbutanoic acid, 2- Ethylbutanoic acid, heptanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, 2,2-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2,4- Dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 3,4-dimethylpentanoic acid, 4,4-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethyl Pentanoic acid, 1,1,2-trimethylbutanoic acid, 1,2,2-trimethylbutanoic acid, 1-ethyl-1-methylbutanoic acid, 1-ethyl-2-methylbutanoic acid, octanoic acid, 2-ethylhexanoic acid, 3 -Ethylhexanoic acid, 3,5-dimethylhexanoic acid, 2,4-dimethylhexanoic acid, 3,4-dimethylhexanoic acid, 4,5-dimethylhexanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid 3-methylheptanoic acid, 4-methylheptanoic acid, 5-methylheptanoic acid, 6-methylheptanoic acid, 2-propylpentanoic acid, nonanoic acid, 2,2-dimethylheptanoic acid, 3,5,5-trimethylhexane Acid, 2-methyloctanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2,2,4,4-te C2-C9 fatty acids such as lamethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid; decanoic acid And fatty acids having 10 to 20 carbon atoms such as undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid and oleic acid.

  When combining 2-methylpentanoic acid and other fatty acids, it is preferable to use a fatty acid other than 2-methylpentanoic acid, a fatty acid having 5 to 7 carbon atoms and / or a branched fatty acid having 8 to 9 carbon atoms. When 2-methylpentanoic acid and a fatty acid having 5 to 7 carbon atoms and / or a branched fatty acid having 8 to 9 carbon atoms are used in combination, 2-methylpentanoic acid and a fatty acid having 5 to 7 carbon atoms and / or a carbon number are used. Both the lubricity in the presence of the difluoromethane refrigerant and the compatibility with the difluoromethane refrigerant tend to be improved as compared with the case where the fatty acids other than the branched fatty acids of 8 to 9 are used in combination. Further, when 2-methylpentanoic acid is used in combination with a fatty acid having 5 to 7 carbon atoms and / or a branched fatty acid having 8 to 9 carbon atoms, the branch having 8 to 9 carbon atoms in the fatty acid constituting the dipentaerythritol fatty acid ester. The proportion of the fatty acid needs to be 80 mol% or less, preferably 75 mol% or less, and more preferably 70 mol% or less. When the proportion of the branched fatty acid having 8 to 9 carbon atoms exceeds 80 mol%, the compatibility with the difluoromethane refrigerant becomes insufficient.

  Moreover, in addition to C5-C7 fatty acid and / or C8-C9 branched fatty acid, when using fatty acids other than these fatty acids, C5-C7 in the fatty acid which comprises dipentaerythritol fatty acid ester. The ratio of the fatty acid and / or the branched fatty acid having 8 to 9 carbon atoms is preferably 60 mol% or more, more preferably 70 mol% or more, and further preferably 80 mol% or more. When the ratio of the fatty acid having 5 to 7 carbon atoms and / or the branched fatty acid having 8 to 9 carbon atoms is within the above range, both lubricity in the presence of the difluoromethane refrigerant and compatibility with the difluoromethane refrigerant are obtained. It tends to be compatible at a higher level.

  Among the dipentaerythritol fatty acid esters according to the present embodiment, those in which the acid component is composed only of 2-methylpentanoic acid and those composed of 2-methylpentanoic acid and a fatty acid having 5 to 7 carbon atoms are difluoromethane refrigerants This is particularly preferable in terms of both the lubricity in the presence and the compatibility with the difluoromethane refrigerant.

  In this embodiment, as long as the fatty acid which comprises dipentaerythritol fatty acid ester satisfy | fills said conditions, the molecular structure of dipentaerythritol fatty acid ester may be single, and 2 of the ester from which molecular structure differs is 2. It may be a mixture of seeds or more.

  When the molecular structure of the dipentaerythritol fatty acid ester is single, that is, when the dipentaerythritol fatty acid ester is constituted by only one type of ester molecule, the ester molecule naturally satisfies the above conditions in its molecular structure. Must meet. On the other hand, when the dipentaerythritol fatty acid ester is a mixture of two or more esters having different molecular structures, it is not always necessary to satisfy the above-mentioned conditions for each molecule. What is necessary is just to satisfy | fill the said conditions as the whole fatty acid which comprises erythritol fatty acid ester.

  As described above, the dipentaerythritol fatty acid ester according to this embodiment includes 2-methylpentanoic acid as an essential component, and includes other fatty acids as constituents as necessary. That is, the dipentaerythritol fatty acid ester may have only one type of fatty acid as an acid component, or may have two or more types of fatty acids having different structures as an acid component. The erythritol fatty acid ester preferably contains, as an acid component, only a fatty acid whose carbon atom adjacent to the carbon of the carbonyl group (α-position carbon atom) is not a quaternary carbon. When the fatty acid constituting the dipentaerythritol fatty acid ester contains a fatty acid having a quaternary carbon at the α-position, the lubricity in the presence of a difluoromethane refrigerant tends to be insufficient.

Preferable examples of the acid component constituting the dipentaerythritol fatty acid ester according to the present invention include the following.
2-methylpentanoic acid;
2-methylpentanoic acid and 1-7 species selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid A combination of
A combination of 2-methylpentanoic acid and 3,5,5-trimethylhexanoic acid;
2-methylpentanoic acid, 3,5,5-trimethylhexanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid A combination with 1 to 7 species selected from the group consisting of:
A combination of 2-methylpentanoic acid and 2-ethylhexanoic acid;
From the group consisting of 2-methylpentanoic acid, 2-ethylhexanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid A combination with 1 to 7 species selected;
A combination of 2-methylpentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-methylpentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-ethylbutanoic acid, 2-ethylpentane A combination with 1 to 7 species selected from the group consisting of acid and 2-methylhexanoic acid;
2-methylpentanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutanoic acid 2,3-dimethylbutanoic acid, 2,4-dimethylbutanoic acid, 3,3-dimethylbutanoic acid, 2-ethylbutanoic acid, heptanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid 5-methylhexanoic acid, 2,2-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2,4-dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 3,4-dimethylpentanoic acid, 4,4 -Dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 1,1,2-trimethylbutanoic acid, 1,2,2-trimethylbutanoic acid, 1-ethyl A combination with 1 to 29 fatty acids selected from ru-1-methylbutanoic acid and 1-ethyl-2-methylbutanoic acid;
2-methylpentanoic acid, 2-ethylhexanoic acid, 3-ethylhexanoic acid, 3,5-dimethylhexanoic acid, 2,4-dimethylhexanoic acid, 3,4-dimethylhexanoic acid, 4,5-dimethylhexanoic acid 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 5-methylheptanoic acid, 6-methylheptanoic acid, 2-propylpentanoic acid, 2,2-dimethyl Heptanoic acid, 3,5,5-trimethylhexanoic acid, 2-methyloctanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2,2,4, From 4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid A combination of 1 to 23 selected fatty acids;
And 2-methylpentanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutane Acid, 2,3-dimethylbutanoic acid, 2,4-dimethylbutanoic acid, 3,3-dimethylbutanoic acid, 2-ethylbutanoic acid, heptanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexane Acid, 5-methylhexanoic acid, 2,2-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2,4-dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 3,4-dimethylpentanoic acid, 4, 4-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 1,1,2-trimethylbutanoic acid, 1,2,2-trimethylbutanoic acid, 1- 1 to 29 selected from ethyl-1-methylbutanoic acid and 1-ethyl-2-methylbutanoic acid, 2-ethylhexanoic acid, 3-ethylhexanoic acid, 3,5-dimethylhexanoic acid, 2,4-dimethylhexane Acid, 3,4-dimethylhexanoic acid, 4,5-dimethylhexanoic acid, 2,2-dimethylhexanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 5-methylheptanoic acid, 6-methylheptanoic acid, 2-propylpentanoic acid, 2,2-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 2-methyloctanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 2- Ethyl-2,3,3-trimethylbutyric acid, 2,2,4,4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4- Tetramethyl pentanoic acid, and one to 23 one fatty acid selected from 2,2-diisopropyl acid, combinations of.

  In the refrigerating machine oil according to the present embodiment, the dipentaerythritol fatty acid ester is mainly used as a base oil. As the base oil of the refrigerating machine oil according to this embodiment, only the dipentaerythritol fatty acid ester may be used alone (that is, the content of the dipentaerythritol fatty acid ester is 100% by mass). Alternatively, in addition to the dipentaerythritol fatty acid ester, polyol esters other than the dipentaerythritol fatty acid ester, complex esters, esters such as alicyclic dicarboxylic acid esters, polyglycol, polyvinyl ether , Ketones, polyphenyl ethers, silicones, polysiloxanes, perfluoroethers and other synthetic oils containing oxygen (hereinafter sometimes referred to as “other oxygenated synthetic oils”) may be used in combination.

  Base oils other than dipentaerythritol fatty acid esters according to the present embodiment include mineral oils, hydrocarbon-based oils such as olefin polymer alkyldiphenylalkanes, alkylnaphthalenes, alkylbenzenes, and the like other than dipentaerythritol fatty acid esters according to the present embodiment. Ester base oils (monoesters, polyol esters containing only linear fatty acids as constituent fatty acids, alkyl aromatic esters, alicyclic carboxylic acid esters, etc.), polyglycols, polyvinyl ethers, ketones, polyphenyl ethers, silicones, polysiloxanes Further, a synthetic oil containing oxygen such as perfluoroether may be used in combination. As the synthetic oil containing oxygen, among the above, esters other than dipentaerythritol fatty acid esters, polyglycols, and polyvinyl ethers according to the present embodiment are preferable, and polyol esters other than dipentaerythritol fatty acid esters are particularly preferable.

  Examples of polyol esters other than dipentaerythritol fatty acid esters include esters of polyhydric alcohols and fatty acids such as neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, pentaerythritol, and the like. An ester of pentyl glycol and a fatty acid and an ester of pentaerythritol and a fatty acid.

  The neopentyl glycol ester is preferably a fatty acid ester having 5 to 9 carbon atoms. Specific examples of such neopentyl glycol esters include neopentyl glycol di 3,5,5-trimethyl hexanate, neopentyl glycol di 2-ethyl hexanate, neopentyl glycol di 2-methyl hexanate, Neopentyl glycol di-2-ethylpentanoate, neopentyl glycol and 2-methylhexanoic acid 2-ethylpentanoic acid ester, neopentyl glycol and 3-methylhexanoic acid 5-methylhexanoic acid ester, neopentyl glycol Esters of 2-methylhexanoic acid, 2-ethylhexanoic acid, neopentyl glycol and 3,5-dimethylhexanoic acid, 4,5-dimethylhexanoic acid, 3,4-dimethylhexanoic acid, neopentyl glycol dipentanate , Neo Emissions chill glycol di-2-ethyl pig sulfonate, neopentyl glycol di-2-methyl-pentanate, neopentyl glycol di-2-methyl-pig sulfonate, neopentyl glycol di methyl-pig sulfonates, and the like.

  As the pentaerythritol ester, pentaerythritol and an ester of a fatty acid having 5 to 7 carbon atoms, an ester of pentaerythritol, a fatty acid having 5 to 7 carbon atoms, and a branched fatty acid having 8 to 9 carbon atoms are preferable. Specific examples of such pentaerythritol esters include esters of pentaerythritol and the following fatty acids.

  2-methylbutanoic acid; 3-methylbutanoic acid; hexanoic acid; 2-methylpentanoic acid; 2-ethylbutanoic acid; 2-ethylpentanoic acid; 2-methylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutane 2 types selected from the group consisting of acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid and hexane 3 types selected from the group consisting of acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2 -From methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid Selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid 5 types selected: 6 selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid Species: Seven types selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid; Acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid and 2-ethylbutane And 2-ethylpentanoic acid and 2-methylhexanoic acid; pentanoic acid and 3,5,5-trimethylhexanoic acid; 2-methylbutanoic acid and 3,5,5-trimethylhexanoic acid; 3-methylbutanoic acid and 3,5,5 5-trimethylhexanoic acid; hexanoic acid and 3,5,5-trimethylhexanoic acid; 2-methylpentanoic acid and 3,5,5-trimethylhexanoic acid; 2-ethylbutanoic acid and 3,5,5-trimethylhexanoic acid; 2-ethylpentanoic acid and 3,5,5-trimethylhexanoic acid; 2-methylhexanoic acid and 3,5,5-trimethylhexanoic acid; pentanoic acid and 2-ethylhexanoic acid; 2-methylbutanoic acid and 2-ethylhexane Acid; 3-methylbutanoic acid and 2-ethylhexanoic acid; hexanoic acid and 2-ethylhexanoic acid; 2-methylpentanoic acid and 2-ethylhexanoic acid; 2 -Ethylbutanoic acid and 2-ethylhexanoic acid; 2-ethylpentanoic acid and 2-ethylhexanoic acid; 2-methylhexanoic acid and 2-ethylhexanoic acid; pentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethyl Hexanoic acid; 2-methylbutanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; 3-methylbutanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; hexanoic acid and 2- Ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; 2-methylpentanoic acid and 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; 2-ethylbutanoic acid and 2-ethylhexanoic acid and 3,5 , 5-trimethylhexanoic acid; 2-ethylpentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; 2-methylhexane And 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2 types selected from the group consisting of 2-methylhexanoic acid and 3,5,5-trimethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid And 2-ethylhexanoic acid selected from the group consisting of 2-ethylpentanoic acid and 2-methylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2 2-ethyl and 2-ethyl selected from the group consisting of ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid Xanthic acid and 3,5,5-trimethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexane 3 types selected from the group consisting of acids and 3,5,5-trimethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethyl 3 types selected from the group consisting of pentanoic acid and 2-methylhexanoic acid and 2-ethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 3 types selected from the group consisting of 2-ethylpentanoic acid and 2-methylhexanoic acid, 2-ethylhexanoic acid and 3, 5,5-trimethylhexanoic acid; from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid 4 types selected and 3,5,5-trimethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2- 4 types selected from the group consisting of methylhexanoic acid and 2-ethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid And 4 selected from the group consisting of 2-methylhexanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethyl 5-Hexane selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid; 3,5,5-trimethylhexanoic acid; consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid 5 types selected from the group and 2-ethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexane 5 types selected from the group consisting of acids, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid 6 and 3,5 selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid , 5-trimethylhexanoic acid; selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid 6 types and 2-ethylhexanoic acid; consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid 6 types selected from the group, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; pentanoic acid, 2 7 types selected from the group consisting of -methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid and 3,5,5-trimethyl Hexanoic acid; seven kinds selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid; 2-ethylhexanoic acid; selected from the group consisting of pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid and 2-methylhexanoic acid 7 types, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; pentanoic acid and 2-methylbutane And 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid, 2-methylhexanoic acid, 3,5,5-trimethylhexanoic acid; pentanoic acid and 2-methylbutanoic acid 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid; pentanoic acid, 2-methylbutanoic acid, and 3-methylbutanoic acid Hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 2-ethylpentanoic acid, 2-methylhexanoic acid, 3,5,5-trimethylhexanoic acid and 2-ethylhexanoic acid.

  In the present embodiment, when a polyol ester other than dipentaerythritol fatty acid ester is blended, it is necessary to be 90% by mass or less, preferably 85% by mass or less, and 80% by mass based on the total amount of refrigerating machine oil. More preferably, it is more preferably 70% by mass or less, still more preferably 60% by mass or less, and most preferably 50% by mass or less. Moreover, when mix | blending oxygen-containing synthetic oils other than a polyol ester, it is necessary that it is 90 mass% or less on the basis of the total amount of refrigerating machine oil, it is preferable that it is 50 mass% or less, and it is 40 mass% or less. More preferably, it is more preferably 30% by mass or less. If the blending amount of polyol esters other than dipentaerythritol fatty acid esters and other oxygen-containing synthetic oils exceeds the upper limit, compatibility with difluoromethane refrigerant and lubricity are hardly achieved at a high level.

  The polyol ester may be a partial ester in which a part of the hydroxyl group of the polyhydric alcohol is not esterified and remains as a hydroxyl group, or may be a complete ester in which all the hydroxyl groups are esterified, A mixture of a partial ester and a complete ester may be used, but the hydroxyl value is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and most preferably 3 mgKOH / g or less.

  Each of the refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment may contain one consisting of one kind of polyol ester having a single structure as a polyol ester other than dipentaerythritol fatty acid ester. , A mixture of two or more polyol esters having different structures may be contained.

  Polyol esters other than dipentaerythritol fatty acid esters are esters of one fatty acid and one polyhydric alcohol, esters of two or more fatty acids and one polyhydric alcohol, one fatty acid and two. Any of ester with 2 or more types of polyhydric alcohol, ester of 2 or more types of fatty acid, and 2 or more types of polyhydric alcohol may be sufficient. Among these, a polyol ester using a mixed fatty acid, particularly a polyol ester constituted by containing two or more fatty acids in the ester molecule is excellent in low temperature characteristics and compatibility with a refrigerant.

  The refrigerating machine oil and the working fluid composition for the refrigerating machine according to the present embodiment may further contain various additives. In the following description, the content of the additive is shown based on the total amount of the refrigerating machine oil, but the content of these components in the working fluid composition for the refrigerating machine is described later when the total amount of the refrigerating machine oil is used as a reference. It is desirable to select so as to be within a preferable range.

  In order to further improve the wear resistance and load resistance of the refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment, phosphoric acid ester, acidic phosphoric acid ester, thiophosphoric acid ester, amine salt of acidic phosphoric acid ester , At least one phosphorus compound selected from the group consisting of chlorinated phosphates and phosphites can be blended. These phosphorus compounds are esters of phosphoric acid or phosphorous acid with alkanols and polyether type alcohols or derivatives thereof.

  Phosphate esters include tryptyl 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. Is mentioned.

  Examples of acidic phosphate esters include monobutyl acyl 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 Examples include hexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, and the like.

  Examples of thiophosphates include tryptyl phosphorothioate, tripentyl phosphorothionate, trihexyl phosphorothioate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl phosphorothionate, tridecyl Phosphorothioate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl phosphorothionate, trihexadecyl phosphorothionate , Triheptadecyl phosphorothioate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, tricresyl phosphorothionate, trixyl Cycloalkenyl phosphorothionate, cresyldiphenyl phosphorothionate, like carboxymethyl Les sulfonyl diphenyl phosphorothionate.

  Examples of the amine salt of an acidic phosphate ester include an amine salt of an acidic phosphate ester and an amine having a primary or tertiary alkyl group having 1 to 24 carbon atoms, preferably 5 to 18 carbon atoms.

  Examples of the amine constituting the acid phosphate ester salt include linear or branched methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, Dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, oleylamine, tetracosylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, Diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine, ditetradecylamine, dipenta Silamine, dihexadecylamine, diheptadecylamine, dioctadecylamine, dioleylamine, ditetracosylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine , Trinonylamine, tridecylamine, triundecylamine, tridodecylamine, tritridecylamine, tritetradecylamine, tripentadecylamine, trihexadecylamine, triheptadecylamine, trioctadecylamine, trioleylamine tritetra And salts with amines such as cosylamine. The amine may be a single compound or a mixture of two or more compounds.

  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, triptyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl Examples thereof include phosphite, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, and tricresyl phosphite. Mixtures of these can also be used.

  When the refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment contain the phosphorus compound, the content of the phosphorus compound is not particularly limited, but is based on the total amount of the refrigerating machine oil (the total amount of the base oil and all the blended additives). Standard), it is preferably 0.01 to 5.0% by mass, more preferably 0.02 to 3.0% by mass. In addition, the said phosphorus compound may be used individually by 1 type, and may use 2 or more types together.

  In addition, a terpene compound can be added to the refrigerating machine oil and the working fluid composition for the refrigerating machine according to the present embodiment in order to further improve the thermal and chemical stability. The “terpene compound” in the present invention means a compound obtained by polymerizing isoprene and a derivative thereof, and a dimer to octamer of isoprene is preferably used. Specific examples of the terpene compound include graniol, nerol, linalool, citral (including granial), citronellol, menthol, limonene, terpineol, carpon, yonon, tuyon, camphor, borneol and other monoterpenes, farnesene, Farnesol, nerolidol, juvenile hormone, humulene, cariophyllene, elemen, casinol, casquitene, tutin and other sesquiterpenes, granyl graniol, phytol, abietic acid, pimaragen, daphnetoxin, taxol, abietic acid, pimaric acid and other diterpenes, Sesterterpenes such as nilfarnesene, triterpenes such as squalene, limonin, cameliagenin, hopane and lanosterol, and tetraterpenes such as carotenoids And the like.

  Among these terpene compounds, monoterpenes, sesquiterpenes and diterpenes are preferable, sesquiterpenes are more preferable, α-farnesene (3,7,11-trimethyldodeca-1,3,6,10-tetraene) and / or β-farnesene. (7,11-dimethyl-3-methylidene deca 1,6,10-triene) is particularly preferred. In this embodiment, a terpene compound may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the terpene compound in the refrigerating machine oil according to this embodiment is not particularly limited, but is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and still more preferably 0, based on the total amount of the refrigerating machine oil. 0.05 to 3% by mass. When the content of the terpene compound is less than 0.001% by mass, the effect of improving the thermal and chemical stability tends to be insufficient, and when it exceeds 10% by mass, the lubricity tends to be insufficient. is there. Further, the content of the terpene compound in the working fluid composition for a refrigerator according to the present embodiment is desirably selected so as to be within the above preferable range when the total amount of the refrigerator oil is used as a reference.

  In addition, the refrigerating machine oil and the working fluid composition for the refrigerating machine according to the present embodiment include a phenyl glycidyl ether type epoxy compound, an alkyl glycidyl ether type epoxy compound, and a glycidyl ester type in order to further improve the thermal and chemical stability. It can contain at least one epoxy compound selected from an epoxy compound, an allyloxirane compound, an alkyloxirane compound, an alicyclic epoxy compound, an epoxidized fatty acid monoester, and an epoxidized vegetable oil.

  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.

  As the alkyl glycidyl ether type epoxy compound, specifically, decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl glycidyl ether, neopentyl glycol diglycidyl ether, Examples thereof include trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, and polyalkylene glycol diglycidyl ether.

  Specific examples of the glycidyl ester type epoxy compound include phenyl glycidyl ester, alkyl glycidyl ester, alkenyl glycidyl ester and the like, and preferable ones include glycidyl-2,2-dimethyloctanoate, glycidyl benzoate, glycidyl. Examples include acrylate and glycidyl methacrylate.

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

  Specific examples of the alkyloxirane compound include 1,2-epoxybutane, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2- Epoxy nonane, 1,2-epoxydecane, 1,2-epoxyundecane, 1,2-epoxydodecane, 1,2-epoxytridecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane, 1,2- Examples include epoxyhexadecane, 1,2-epoxyheptadecane, 1,1,2-epoxyoctadecane, 2-epoxynonadecane, 1,2-epoxyicosane and the like.

  Specific 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-epoxynorpolnan, 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 Examples thereof include 2-methylcyclohexane and 4-epoxyethyl-1,2-epoxycyclohexane.

  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, ptyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and ptylphenyl esters of epoxy stearic acid are preferably used.

  Specific examples of the epoxidized vegetable oil 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. Of these, phenyl glycidyl ether type epoxy compounds and glycidyl ester type epoxy compounds are more preferred, and phenyl glycidyl ether, butyl phenyl glycidyl ether, alkyl glycidyl esters or mixtures thereof are particularly preferred.

  When the refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment contain the epoxy compound, the content of the epoxy compound is not particularly limited, but is 0.1 to 5.0% by mass based on the total amount of the refrigerating machine oil. It is preferable that it is 0.2-2.0 mass%. In addition, the said epoxy compound may be used individually by 1 type, and may use 2 or more types together.

  In addition, the refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment can contain conventionally known additives for refrigerating machine oil as necessary in order to further enhance the performance. Examples of such additives include phenolic antioxidants such as di-tert-butyl-p-cresol and bisphenol A, phenyl-α-naphthylamine, N, N-di (2-naphthyl) -p-phenylenediamine, and the like. Amine-based antioxidants, anti-wear agents such as zinc dithiophosphate, extreme pressure agents such as chlorinated paraffin and sulfur compounds, oil-based agents such as fatty acids, antifoaming agents such as silicones, metal inertness such as benzotriazole Agents, viscosity index improvers, pour point depressants, detergent dispersants and the like. These additives may be used individually by 1 type, and may be used in combination of 2 or more type. The content 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.

Kinematic viscosity of the refrigerating machine oil according to the present embodiment is not particularly limited, the kinematic viscosity at 40 ° C., preferably 3~1000mm ² / s, more preferably 4~500mm ² / s, and most preferably 5~400mm ² / s. The kinematic viscosity at 100 ° C. is preferably 1 to 100 mm ² / s, more preferably ² to 50 mm ² / s. When the kinematic viscosity is less than the lower limit value, the lubricity tends to be insufficient. On the other hand, when the kinematic viscosity exceeds the upper limit value, the compatibility with the difluoromethane refrigerant tends to be insufficient.

Further, the volume resistivity of the refrigerating machine oil according to the present embodiment is not particularly limited, but is preferably 1.0 × 10 ¹² Ω · cm or more, more preferably 1.0 × 10 ¹³ Ω · cm or more, most preferably 1. 0.0 × 10 ¹⁴ Ω · cm or more. In particular, when it is used for a hermetic refrigerator, high electrical insulation tends to be required. In the present invention, the volume resistivity means a value at 25 ° C. measured in accordance with JIS C2101 “Electrical Insulating Oil Test Method”.

  In addition, the water content of the refrigerating machine oil according to the present embodiment is not particularly limited, but is preferably 200 ppm or less, more preferably 100 ppm or less, and most preferably 50 ppm or less based on the total quantity of refrigerating machine oil. In particular, when it is used for a hermetic type refrigerator, the moisture content is required to be small from the viewpoint of the influence on the thermal / chemical stability and electrical insulation of the refrigerator oil.

  In addition, the acid value of the refrigerating machine oil according to the present embodiment is not particularly limited, but is preferably 0.1 mgKOH / g or less, more preferably 0. 0 to prevent corrosion of the metal used in the refrigerating machine or piping. It can be set to 05 mgKOH / g or less. In addition, in this invention, an acid value means the acid value measured based on JISK2501 "Petroleum product and lubricating oil one-neutralization number test method".

  In addition, the ash content of the refrigerating machine oil according to the present embodiment is not particularly limited, but in order to increase the thermal and chemical stability of the refrigerating machine oil according to the present embodiment and suppress the generation of sludge, preferably 100 ppm or less, more preferably It can be 50 ppm or less. In the present invention, the ash means the value of ash measured in accordance with JIS K2272 “Testing method for ash and sulfated ash of crude oil and petroleum products”.

  The refrigerating machine oil according to the present embodiment exhibits sufficiently high lubricity and sufficiently high compatibility when used with a difluoromethane refrigerant, and can be widely used as a refrigerating machine oil for a refrigerating machine for a difluoromethane refrigerant. it can. Specifically, as the refrigerator in which the refrigerator oil according to the present embodiment is used, a room air conditioner, a packaged air conditioner, a refrigerator, an automotive air conditioner, a dehumidifier, a freezer, a freezer / refrigerated warehouse, a vending machine, a showcase, a chemical Although cooling apparatuses, such as a plant, are mentioned, Above all, it is particularly preferably used in a refrigerator having a hermetic compressor. Moreover, the refrigerating machine oil according to the present embodiment can be used for any type of compressor such as a reciprocating type, a rotary type, and a centrifugal type. In these refrigerators, the refrigerator oil according to the present embodiment is used as a working fluid composition for a refrigerator mixed with a difluoromethane refrigerant, as will be described later.

  That is, the working fluid composition for a refrigerator according to the present embodiment contains the above-described refrigerator oil for a difluoromethane refrigerant and a difluoromethane refrigerant. Here, the blending ratio of the refrigerating machine oil and the difluoromethane refrigerant in the working fluid composition for a refrigerating machine according to the present embodiment is not particularly limited, but the blending quantity of the refrigerating machine oil is usually based on 100 parts by weight of difluoromethane. It is 1-1000 weight part, Preferably it is 2-800 weight part.

  In addition, in the working fluid composition for a refrigerator according to the present embodiment, it is possible to achieve both sufficiently high lubricity and sufficiently high compatibility that were not obtained when using conventional refrigerator oil. In this respect, the usefulness is most exerted when only the difluoromethane refrigerant is contained as the refrigerant component, but the HFC refrigerant other than the difluoromethane refrigerant, the unsaturated fluorinated hydrocarbon (HFO) refrigerant, and the trifluoroiodomethane. It may contain a refrigerant, a fluorine-containing ether refrigerant such as perfluoroethers, a non-fluorine-containing ether refrigerant such as dimethyl ether, or a natural refrigerant such as ammonia, carbon dioxide or hydrocarbon.

  Examples of HFC refrigerants other than difluoromethane include hydrofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms. Specifically, for example, trifluoromethane (HFC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoro Ethane (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), and 1,1,1,3,3-pentafluorobutane HFC-365mfc), or a mixture of two or more thereof. 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 Such as a mixture 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.

  As the unsaturated fluorinated hydrocarbon (HFO) refrigerant, fluoropropene having 3 to 5 fluorine atoms is preferable, and 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3, 3-tetrafluoropropene (HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-C1234ye), and 3,3 It is preferably one or a mixture of two or more of 3-trifluoropropene (HFO-1243zf). From the viewpoint of the physical properties of the refrigerant, one or more selected from HFO-1225ye, HFO-1234ze, and HFO-1234yf are preferable. A preferable refrigerant mixed with the HFO refrigerant is difluoromethane / 1234yf = 40-60 / 60-40% by weight, and among them, difluoromethane / 1234yf = 50/50% by weight is preferable.

  The hydrocarbon refrigerant is preferably a hydrocarbon having 3 to 5 carbon atoms, 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 these, gas at 25 ° C. and 1 atm is preferably used, and propane, normal butane, isobutane, 2-methylbutane or a mixture thereof is preferable.

  Specific examples of the fluorine-containing ether 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, These refrigerant | coolants are suitably selected according to a use or required performance.

  The refrigerating machine oil according to this embodiment is usually present in the form of a working fluid composition for a refrigerating machine mixed with a difluoromethane refrigerant or a mixed refrigerant of a difluoromethane refrigerant and the above-described refrigerant in a refrigerating and air-conditioning apparatus. Yes. The mixing ratio of the refrigerating machine oil and the refrigerant in the composition and the mixing ratio of the refrigerating machine oil and the refrigerant in the working fluid composition for a refrigerating machine of the present invention are not particularly limited, but the refrigerating machine oil is preferable with respect to 100 parts by mass of the refrigerant. Is 1 to 1000 parts by mass, more preferably 2 to 800 parts by mass.

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

  The working fluid composition for a refrigerator according to the present embodiment can be suitably used for various difluoromethane refrigerant refrigerators as described above, but as a typical configuration of the refrigerant circulation cycle provided in the refrigerator. Is exemplified by a compressor, a condenser, an expansion mechanism and an evaporator, and optionally a dryer.

  The compressor includes 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 compression 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, The rotary shaft fitted to the rotor and the compressor unit connected to the motor via the rotary shaft are housed, and the high-pressure refrigerant gas discharged from the compressor unit is outside the sealed container. Examples include a low-pressure container type compressor that is directly discharged.

  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. Moreover, as a magnet wire used for the motor part, 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 and Comparative Examples 1-9]
In Examples 1-2 and Comparative Examples 1-9, sample oils were prepared using base oils 1-11 shown below, respectively. Tables 1 to 3 show properties of the obtained sample oils (kinematic viscosity at 40 ° C. and 100 ° C., total acid value).
(Base oil)
Base oil 1: Hexaester base oil of dipentaerythritol and 2-methylpentanoic acid 2: Dipentaerythritol and fatty acid mixture (mixture of 2-methylpentanoic acid 50 mol%, 2-ethylbutanoic acid 50 mol%)
Base oil 3: tetraester base oil of pentaerythritol and n-pentanoic acid 4: hexaester base oil of dipentaerythritol and n-pentanoic acid 5: diester base oil of neopentyl glycol and 2-methylpentanoic acid 6 : Triester base oil of trimethylolpropane and 2-methylpentanoic acid 7: Tetraester base oil of pentaerythritol and 2-methylpentanoic acid 8: Tetraester base oil of pentaerythritol and 2-ethylbutanoic acid 9: Di Hexaester base oil of pentaerythritol and 2-ethylbutanoic acid 10: Tetraester base oil of pentaerythritol and carboxylic acid mixture (2-methylhexanoic acid 70 mol%, 2-ethylpentanoic acid 30 mol%) 11: Pentaerythritol And carboxylic acid mixture (2-ethylhexanoic acid 5 Mol%, 3,5,5 tetraester of trimethyl hexanoic acid 50 mol%)

  Next, the following tests were performed on the above sample oils.

(Compatibility test with refrigerant)
In accordance with JIS-K-2211 “Refrigerating machine oil” “Compatibility test method with refrigerant”, gradually add a mixture of 18 g of difluoromethane refrigerant (HFC-32) and 2 g of sample oil from 30 ° C. to −40 ° C. Upon cooling, the temperature at which the mixture phase separated or became cloudy was measured. The obtained results are shown in Tables 1-3. In Tables 1 to 3, “<−40” means that no phase separation or cloudiness was observed in the measurement temperature range of this test, and “separation” means phase separation or cloudiness already at 30 ° C. Represents what you were doing.

(Lubricity test)
A friction tester using a vane (SKH-51) as an upper test piece and a disk (FC250HRC40) as a lower test piece was mounted inside the sealed container. After 600 g of sample oil was introduced into the friction test site and the inside of the system was vacuum degassed, HFC-32 was introduced and heated. After the temperature in the sealed container was 100 ° C. and the refrigerant pressure was 1.5 MPa, the load was increased stepwise to 100 kgf at a load step of 10 kgf (step time: 2 minutes). For each sample oil, the wear width of the vane and the wear depth of the disk after 60 minutes of the test were measured.

(Low temperature precipitation test)
The sample oil was put in a test tube and immersed in an ethanol bath (-70 ° C.) containing dry ice for 24 hours, and the presence or absence of cloudiness was observed.

(Stability test)
A 200 ml autoclave was filled with 85 g of sample oil whose water content was adjusted to 1000 ppm and 15 g of HFC-32, and the acid value of the sample oil after heating at 175 ° C. for 500 hours was measured.

Claims (2)

An ester of dipentaerythritol and a fatty acid, wherein the fatty acid is a fatty acid selected from the group consisting of fatty acids having 5 to 7 carbon atoms and branched fatty acids having 8 to 9 carbon atoms , An ester having a ratio of 30 mol% or more, containing 30 mass% or more based on the total amount of the refrigerating machine oil
The kinematic viscosity at 100 ° C. is 1 to 100 mm ² / s,
A refrigerating machine oil characterized by being used together with a difluoromethane refrigerant.   A working fluid composition for a refrigerator, comprising the refrigerator oil according to claim 1 and a difluoromethane refrigerant.