JP5525877B2 - Refrigerator oil and working fluid composition for refrigerator - Google Patents

Description

  The present invention relates to a refrigerating machine oil and a working fluid composition for a refrigerating machine, and more specifically, a refrigerating machine oil useful when used with a difluoromethane refrigerant (HFC-32), and a refrigerating machine operation using the refrigerating machine oil. It relates to a fluid composition.

  Due to the problem of ozone depletion in recent years, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon), which have been used as refrigerants in conventional refrigeration equipment, are subject to regulation. Instead, HFC (hydrofluorocarbon) is used as a refrigerant. 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 a thermodynamic characteristic that is a measure of refrigerant performance is approximately the same as that of the HFC. The use of propene 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 is put into the cycle. As a result, the amount of refrigerating machine oil in the refrigerant compressor is reduced, resulting in poor lubrication and the problem of closing an expansion mechanism such as a capillary.

  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 problems, the present invention provides an ester of pentaerythritol and a fatty acid, wherein the fatty acid has a molar ratio of branched fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid of 20. : 80 to 80:20, and an ester in which the total proportion of the fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid in the fatty acid is 20 mol% or more is 10% by mass based on the total amount of the refrigerating machine oil A refrigerating machine oil containing the above and used with a difluoromethane refrigerant is provided.

  The refrigerating machine oil of the present invention is preferably one that gives a solubility of 25 to 35% by mass of difluoromethane in the refrigerating machine oil when enclosed in a sealed container together with difluoromethane and kept at a temperature of 40 ° C. and a pressure of 2 MPa.

  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 according to the present embodiment is an ester of pentaerythritol and a fatty acid, and in the fatty acid, the molar ratio of the branched fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid is from 20:80 to 80:20, an ester in which the total proportion of the fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid in the fatty acid is 20 mol% or more (hereinafter, sometimes referred to as “pentaerythritol fatty acid ester”) Is 10% by mass or more based on the total amount of refrigerating machine oil, and is used together with a difluoromethane refrigerant.

  In the refrigerating machine oil according to the present embodiment, the content of the pentaerythritol fatty acid ester is 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more, based on the total amount of the refrigerating machine oil. It is. The refrigerating machine oil according to the present embodiment may contain a lubricating oil base oil and additives other than pentaerythritol fatty acid ester as described later, but if the pentaerythritol fatty acid ester is less than 10% by mass, lubricity and It becomes impossible to achieve compatibility with compatibility at a high level. The pentaerythritol fatty acid ester includes a complete ester in which all the hydroxyl groups of pentaerythritol are esterified, a partial ester in which some of the hydroxyl groups of pentaerythritol remain without being esterified, and a complete ester and a partial ester. A complete ester is preferred.

  In the fatty acid constituting the pentaerythritol fatty acid ester, the molar ratio of branched fatty acid having 6 carbon atoms to 3,5,5-trimethylhexanoic acid is 20:80 to 80:20, preferably 25:75. It is -75: 25, More preferably, it is 30: 70-70: 30. Moreover, the total ratio of the fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid in the fatty acid constituting the pentaerythritol fatty acid ester is 20 mol% or more. If the above-mentioned conditions relating to the fatty acid composition are not satisfied, sufficient compatibility with the difluoromethane refrigerant, moderate solubility with the difluoromethane refrigerant, and low-temperature fluidity are hardly achieved at a high level. In addition, the ratio of the fatty acid as referred to in the present invention is a value based on the total amount of fatty acid constituting the pentaerythritol fatty acid ester contained in the refrigerating machine oil.

  Specific examples of the branched fatty acid having 6 carbon atoms include 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid, 2, Examples thereof include 3-dimethylbutanoic acid, among which 2-methylpentanoic acid and 2-ethylbutanoic acid are preferable.

  The pentaerythritol fatty acid ester according to this embodiment has a branched carbon number as long as the molar ratio of branched fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid is 20:80 to 80:20. Fatty acids other than 6 fatty acids and 3,5,5-trimethylhexanoic acid may be contained as constituent acid components.

  Specific examples of fatty acids other than branched fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid include acetic acid, propionic acid, butanoic acid, 2-methylpropionic acid, pentanoic acid, and 2-methylbutanoic acid. , 3-methylbutanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, heptanoic acid, 2-methylhexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, 2,2-dimethylpentane 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-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, 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-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid, etc. Acids; decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, oleic acid and the like, and the like It is done.

  In the case of combining a branched C6 fatty acid with 3,5,5-trimethylhexanoic acid and other fatty acids, the other fatty acids include C5 to C7 fatty acids and / or C8 to C9. It is preferable to use the branched fatty acid. In the following description, the “fatty acid having 5 to 7 carbon atoms” does not include “the fatty acid having 6 carbon atoms having a branch”, and the “branched fatty acid having 8 to 9 carbon atoms” includes “3, 5 , 5-trimethylhexanoic acid ”is not included.

  The number of carbons having a branch when a branched C6 fatty acid, 3,5,5-trimethylhexanoic acid and a C5-7 fatty acid and / or a C8-9 branched fatty acid are used in combination. Difluoromethane refrigerant is present in comparison with the case of using a combination of 6 fatty acids, 3,5,5-trimethylhexanoic acid and fatty acids other than fatty acids having 5 to 7 carbon atoms and / or branched fatty acids having 8 to 9 carbon atoms Both the lower lubricity and the compatibility with the difluoromethane refrigerant tend to be further improved. In addition, when a branched C6 fatty acid, 3,5,5-trimethylhexanoic acid and a C5-7 fatty acid and / or a C8-9 branched fatty acid are used in combination, a pentaerythritol fatty acid ester The proportion of the branched fatty acid having 8 to 9 carbon atoms in the fatty acid that constitutes is required 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, it is C5-C7 in the fatty acid which comprises pentaerythritol fatty acid ester. The proportion of fatty acids and / or branched fatty acids 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 pentaerythritol fatty acid esters according to the present embodiment, those in which the acid component is composed of only a branched C6 fatty acid and 3,5,5-trimethylhexanoic acid are lubricity in the presence of a difluoromethane refrigerant. This is particularly preferable in terms of compatibility with the difluoromethane refrigerant.

  The pentaerythritol fatty acid ester according to the present embodiment may be a mixture of two or more esters having different molecular structures. In such a case, the individual molecules do not necessarily satisfy the above-described conditions. What is necessary is just to satisfy | fill the said conditions as the whole fatty acid which comprises the pentaerythritol fatty acid ester contained in it.

  As described above, the pentaerythritol fatty acid ester according to the present embodiment includes a branched C6 fatty acid and 3,5,5-trimethylhexanoic acid, and includes other fatty acids as constituents as necessary. . That is, the pentaerythritol fatty acid ester according to the present embodiment may have only one type of fatty acid as an acid component, or may have two or more different fatty acids as an acid component. However, it is preferable that the pentaerythritol fatty acid ester contains only a fatty acid in which the carbon atom adjacent to the carbonyl carbon (α-position carbon atom) is not a quaternary carbon as an acid constituent. When the fatty acid constituting the pentaerythritol fatty acid ester contains a fatty acid having an α-position carbon atom that is a quaternary carbon, the lubricity in the presence of a difluoromethane refrigerant tends to be insufficient.

Preferable examples of the acid component constituting the pentaerythritol fatty acid ester according to the present invention include the following.
(I) 1-6 kinds selected from 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid and 2,3-dimethylbutanoic acid; A combination with 3,5,5-trimethylhexanoic acid;
(Ii) 1-6 kinds selected from 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid and 2,3-dimethylbutanoic acid; 3,5,5-trimethylhexanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methyl Pentanoic 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-dimethylpen 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-1-methylbutanoic acid and 1-30 selected from 1-ethyl-2-methylbutanoic acid in combination;
(Iii) 1-6 selected from 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid and 2,3-dimethylbutanoic acid; 3,5,5-trimethylhexanoic 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-dimethylheptanoic acid, 2-methyloctanoic acid, 2-ethylheptanoic acid, 3-methyloctanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2, , 4,4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2,2,3,4-tetramethylpentanoic acid and 2,2-diisopropylpropionic acid In combination with;
(Iv) 1-6 selected from 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylbutanoic acid, 2,2-dimethylbutanoic acid and 2,3-dimethylbutanoic acid; 3,5,5-trimethylhexanoic acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methyl Pentanoic 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-dimethylpen 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-1-methylbutanoic acid and 1-ethyl-2-methylbutanoic 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-dimethylheptanoic acid, 2-methyloctanoic acid, 2-ethyl Heptanoic acid, 3-methyloctanoic acid, 2-ethyl-2,3,3-trimethylbutyric acid, 2,2,4,4-tetramethylpentanoic acid, 2,2,3,3-tetramethylpentanoic acid, 2, A combination with 1 to 22 species selected from 2,3,4-tetramethylpentanoic acid and 2,2-diisopropylpropionic acid.

  In the refrigerating machine oil according to the present embodiment, the pentaerythritol fatty acid ester is mainly used as a base oil. As the base oil of the refrigerating machine oil according to the present embodiment, only the pentaerythritol fatty acid ester may be used alone (that is, the content of the pentaerythritol fatty acid ester according to the present embodiment is 100% by mass). To the extent that the excellent performance is not impaired, other polyol esters and complex esters other than the above pentaerythritol fatty acid esters, esters such as alicyclic dicarboxylic acid esters, polyglycols, polyvinyl ethers, ketones, polyphenyl ethers, silicones , Synthetic oils containing oxygen such as polysiloxane and perfluoroether (hereinafter referred to as “other oxygen-containing synthetic oils” in some cases) may be used in combination.

  As base oils other than the pentaerythritol fatty acid ester according to the present embodiment, mineral oil, hydrocarbon-based oils such as olefin polymer alkyldiphenylalkane, alkylnaphthalene, and alkylbenzene, and ester systems other than the pentaerythritol fatty acid ester according to the present embodiment Base oil (monoester, ester of polyhydric alcohol and fatty acid other than pentaerythritol, ester of fatty acid and pentaerythritol whose fatty acid composition does not satisfy the above conditions, alkyl aromatic ester, alicyclic carboxylic acid ester, etc.), poly Synthetic oils containing oxygen such as glycol, polyvinyl ether, ketone, polyphenyl ether, silicone, polysiloxane, perfluoroether may be used in combination. As the synthetic oil containing oxygen, among the above, esters other than the polyol ester according to the present invention, polyglycol, and polyvinyl ether are preferably used.

  Among the other oxygen-containing synthetic oils described above, particularly preferred are polyol esters other than pentaerythritol fatty acid esters. Examples of polyol esters other than pentaerythritol fatty acid esters include esters of polyhydric alcohols and fatty acids such as neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, and dipentaerythritol. An ester of pentyl glycol and a fatty acid and an ester of dipentaerythritol 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 dipentaerythritol esters, dipentaerythritol and esters of fatty acids having 5 to 7 carbon atoms, dipentaerythritol and esters of fatty acids having 5 to 7 carbon atoms and fatty acids having 8 to 9 carbon atoms are preferable. Specific examples of such dipentaerythritol esters include dipentaerythritol, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, and 2-ethyl. Examples thereof include esters with one or more fatty acids selected from pentanoic acid, 2-methylhexanoic acid, 3,5,5-trimethylhexanoic acid and 2-ethylhexanoic acid.

  When the refrigerating machine oil according to the present embodiment is blended with an oxygen-containing synthetic oil other than pentaerythritol fatty acid ester, the blending amount of the oxygen-containing synthetic oil other than the pentaerythritol fatty acid ester is excellent lubricity of the refrigerating machine oil according to the present embodiment. The compatibility is not particularly limited as long as the compatibility is not impaired, but when a polyol ester other than the pentaerythritol fatty acid ester according to the present embodiment is blended, it is necessary to be 90% by mass or less based on the total amount of the refrigerating machine oil. 85% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, still more preferably 60% by mass or less, and even more preferably 50% by mass. Most preferably: when blending oxygen-containing synthetic oils other than polyol esters, refrigerators It is necessary that in the total amount is 50 mass% or less, preferably 40 wt% or less, more preferably 30% by mass or less. If the blending amount of polyol ester other than pentaerythritol fatty acid ester or other oxygen-containing synthetic oil exceeds the upper limit, the characteristics of the present invention cannot be obtained.

  The polyol ester other than the pentaerythritol fatty acid ester according to this embodiment may be a partial ester in which a part of the hydroxyl groups of the polyhydric alcohol is not esterified and remains as a hydroxyl group, and all the hydroxyl groups are ester. It may be a complete ester or a mixture of a partial ester and a complete ester, but the hydroxyl value is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, most preferably 3 mgKOH / g or less. It is preferable that

  Each of the refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment contains one kind of polyol ester having a single structure as a polyol ester other than the pentaerythritol fatty acid ester according to the present embodiment. It may also contain a mixture of two or more polyol esters having different structures.

  Further, polyol esters other than pentaerythritol fatty acid ester according to this embodiment are esters of one fatty acid and one polyhydric alcohol, esters of two or more fatty acids and one polyhydric alcohol, and one kind. Any of an ester of the above fatty acid and two or more polyhydric alcohols, an ester of two or more fatty acids and two or more polyhydric alcohols may be used.

  The refrigerating machine oil according to the present embodiment may be composed only of pentaerythritol fatty acid ester, or may be composed of pentaerythritol fatty acid ester and other base oil. May further be contained. Moreover, the working fluid composition for a refrigerator according to this 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.

  Specifically, for example, as phosphate ester, tryptyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl phosphate Decyl phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, And xylenyl diphenyl phosphate.

  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 derivatives thereof, and isoprene dimer to octamer are 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-trimethyldodeca1,3,6,10-tetraene) and / or β-farnesene. (7,11-dimethyl-3-methylidene deca 1,6,10-triene) is particularly preferred. In this invention, 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 include 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.

  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-epoxycyclohexane carboxylate, 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- Examples thereof include epoxy-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, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxy stearate 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".

  Further, the ash content of the refrigerating machine oil according to the present embodiment is not particularly limited, but is preferably 100 ppm or less, more preferably 50 ppm or less in order to increase the thermal / chemical stability of the refrigerating machine oil and suppress the generation of sludge and the like. Can do. In the present invention, 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 is widely used as a refrigerating machine oil for a refrigerating machine for a difluoromethane refrigerant. Can do. 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. Further, the refrigerating machine oil for difluoromethane refrigerant of the present invention can be used in any type of compressor such as a reciprocating type, a rotary type, a centrifugal type and the like. In these refrigerators, the refrigerating machine oil for difluoromethane refrigerant of the present invention 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 includes the refrigerator oil and the difluoromethane refrigerant according to the present embodiment. 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 to 10 and Comparative Examples 1 to 11]
In Examples 1 to 10 and Comparative Examples 1 to 11, sample oils were prepared by blending the base oils 1 to 13 and the additives 1 to 4 shown below to the composition ratios shown in Table 1 or Table 2, respectively. did. Tables 1 to 4 show the properties of the obtained sample oils.
(Base oil)
Base oil 1: tetraester base oil with pentaerythritol and fatty acid mixture (mixture of 2-methylpentanoic acid 70 mol%, 3,5,5-trimethylhexanoic acid 30 mol%) 2: pentaerythritol and fatty acid mixture (2- Tetraester base oil 3: mixture of 30 mol% methylpentanoic acid and 70 mol% 3,5,5-trimethylhexanoic acid): tetraester base oil of pentaerythritol and n-pentanoic acid 4: dipentaerythritol and n -Hexaester base oil with pentanoic acid 5: Diester base oil with neopentyl glycol and 2-methylpentanoic acid 6: Triester base oil with trimethylolpropane and 2-methylpentanoic acid 7: Pentaerythritol and 2-methyl Tetraester base oil with pentanoic acid 8: pentaerythritol and 2-ethylbutane Tetraester base oil 9: Hexaester base oil 10 of dipentaerythritol and 2-ethylbutanoic acid 10: Pentaerythritol and fatty acid mixture (2-methylhexanoic acid 70 mol%, 2-ethylpentanoic acid 30 mol%) Tetraester base oil 11: Tetraester base oil 12: pentaerythritol and fatty acid mixture (2-ethylhexanoic acid 50 mol%, 3,5,5-trimethylhexanoic acid 50 mol%) Tetraester base oil 13 with a mixture of 90 mol% methylpentanoic acid and 10 mol% 2-3,5,5-trimethylhexanoic acid): a mixture of pentaerythritol and fatty acid (10 mol% 2-methylpentanoic acid, 2-3 , 5,5-trimethylhexanoic acid 90 mol% mixture) tetraester (addition) )
Additive 1: Tricresyl phosphate additive 2: Triphenyl phosphorothioate additive 3: Glycidyl-2,2-dimethyloctanoate additive 4: pt-butylphenyl glycidyl ether

  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 evaluated as the two-layer separation temperature. Note that “<−40” indicates that phase separation and cloudiness were not observed in the measurement temperature range of this test. In Table 4, “separation” means that phase separation or cloudiness has already occurred at 30 ° C.

(Lubricity test)
A friction tester using a vane (SKH-51) as an upper test piece and a disk (FC250 HRC40) 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 setting the temperature in the sealed container to 100 ° C. and the refrigerant pressure to 1.5 MPa, the load was gradually increased to 100 kgf at a load step of 10 kgf (step time: 2 minutes), and a wear test was performed at 100 kgf for 60 minutes. For each sample oil, the wear width of the vane and the wear depth of the disc after the 60-minute 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.

Claims (2)

  An ester of pentaerythritol and a fatty acid, in which the molar ratio of the branched fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid is 20:80 to 80:20, It contains 10 mass% or more of an ester in which the total proportion of the fatty acid having 6 carbon atoms and 3,5,5-trimethylhexanoic acid is 20 mol% or more based on the total amount of refrigerating machine oil, and is used together with a difluoromethane refrigerant. Features refrigeration oil. A working fluid composition for a refrigerator, comprising the refrigerator oil according to claim 1 and a difluoromethane refrigerant.