JP5919430B2 - Refrigeration oil - Google Patents

Description

  The present invention relates to refrigerating machine oil and a refrigerating machine fluid composition, and more particularly to refrigerating machine oil useful when used together with a difluoromethane refrigerant (HFC-32).

  Due to the chlorofluorocarbon regulations regarding the ozone depletion problem, in refrigeration and air conditioning equipment, CFC-11, CFC-12, HCFC-22 and other chlorine-containing chlorofluorocarbons (CFC) to HFC-32, HFC-125, HFC-134a, etc. Substitution of non-chlorine-containing chlorofluorocarbons (hydrofluorocarbons, HFCs) is being promoted. When using non-chlorine-containing chlorofluorocarbon refrigerants, naphthenic mineral oils and paraffinic mineral oils that have been conventionally used as refrigeration oils do not satisfy refrigerant compatibility, which is one of the required performances of refrigeration oils. Application of ester oils disclosed in Patent Document 1 and Patent Document 2 has been studied.

  In recent years, due to the global warming problem, some of the HFC refrigerants are in the direction of being regulated. Accordingly, among the HFC refrigerants, difluoromethane refrigerant (HFC-32) having a low global warming potential and high refrigeration efficiency is drawing attention.

  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.

  Therefore, in order to avoid such a phenomenon, development of a refrigerating machine oil for difluoromethane refrigerant has been advanced. For example, ester refrigerating machine oils disclosed in Patent Document 3 and Patent Document 4 have been proposed.

Japanese National Patent Publication No. 3-505602 Japanese Patent Laid-Open No. 3-128992 JP-A-6-17073 JP-A-10-298572

  However, when the above-mentioned conventional ester refrigerating machine oil is used, the compatibility with the difluoromethane refrigerant is improved, but sufficient lubricity cannot be obtained in the presence of the difluoromethane refrigerant. It was still not enough to serve.

  The present invention has been made in view of the above-described problems of the prior art, and is a refrigeration for a difluoromethane refrigerant having a sufficiently high refrigerant compatibility and a sufficiently high lubricity even when used with a difluoromethane refrigerant. The purpose is to provide machine oil.

  As a result of intensive studies to achieve the above object, the inventors of the present invention, in a refrigerating machine oil containing a specific amount of an ester of dipentaerythritol and a fatty acid, when the fatty acid constituting the ester has a specific composition The present inventors have found that the problem can be solved and have solved the present invention.

  That is, the refrigerating machine oil for difluoromethane refrigerant of the present invention contains an ester of dipentaerythritol and a fatty acid in an amount of 20% by mass or more based on the total amount of the refrigerating machine oil, and the ratio of the fatty acid having 5 to 7 carbon atoms in the fatty acid constituting the ester. The fatty acid which is 20 mol% or more and which constitutes an ester contains a branched fatty acid having 8 to 9 carbon atoms.

  The refrigerating machine oil preferably further contains 0.1 to 5% by mass of an epoxy compound based on the total amount of the refrigerating machine oil.

  As described above, according to the refrigerating machine oil for difluoromethane refrigerant of the present invention, it is possible to obtain sufficiently high refrigerant compatibility and sufficiently high lubricity even when used with a difluoromethane refrigerant. .

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

  In the refrigerating machine oil for difluoromethane refrigerant of the present invention, 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 based on the total amount of the refrigerating machine oil. More preferably, it is 20% by mass or more, and more preferably 30% by mass or more. The refrigerating machine oil for difluoromethane refrigerant of the present invention may contain a base oil and an additive other than dipentaerythritol fatty acid ester as described later, but if the dipentaerythritol fatty acid ester is less than 10% by mass, Compatibility and compatibility cannot be achieved at a high level. The dipentaerythritol fatty acid ester according to the present invention is a complete ester in which all the hydroxyl groups of dipentaerythritol are esterified, and a partial ester in which some of the hydroxyl groups of dipentaerythritol remain without being esterified. , And a mixture of a complete ester and a partial ester, but a complete ester is preferable.

  In the present invention, the proportion of the fatty acid having 5 to 7 carbon atoms in the fatty acid constituting the dipentaerythritol fatty acid ester needs to be 20 mol% or more, preferably 25 mol% or more, more preferably 30. More than mol%. When the proportion of the fatty acid having 5 to 7 carbon atoms is less than the lower limit, it is difficult to achieve both high lubricity in the presence of the difluoromethane refrigerant and compatibility with the difluoromethane refrigerant at a high level. In addition, the ratio of the C5-C7 fatty acid referred to in the present invention is a value based on the total amount of fatty acids constituting the dipentaerythritol fatty acid ester contained in the refrigerating machine oil.

  As the fatty acid having 5 to 7 carbon atoms according to the present invention, a linear or branched saturated fatty acid is preferably used, and specifically, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2,2-dimethylpropane. Acid, hexanoic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutanoic acid, 2,3-dimethylbutanoic acid, 2-ethylbutanoic acid, heptanoic acid, 2-methyl Hexanoic acid, 3-methylhexanoic acid, 4-methylhexanoic acid, 5-methylhexanoic acid, 2,2-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2,4-dimethylpentanoic acid, 3,3-dimethyl Pentanoic acid, 3,4-dimethylpentanoic acid, 4,4-dimethylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 1,1,2-trimethylbutane Phosphate, 1,2,2-trimethyl butanoic acid, 1-ethyl -1-methylbutanoic acid, 1-ethyl-2-methylbutanoic acid. Among these, from the aspect of compatibility with the difluoromethane refrigerant, linear fatty acids having 5 to 6 carbon atoms and / or branched fatty acids having 5 to 7 carbon atoms are preferably used. From the viewpoint of lubricity, straight chain fatty acids having 5 to 6 carbon atoms are preferably used, and from the viewpoint of hydrolysis stability, branched fatty acids having 5 to 7 carbon atoms are preferably used.

  In the present invention, the dipentaerythritol fatty acid ester may contain a fatty acid other than a fatty acid having 5 to 7 carbon atoms as a constituent acid component as long as it contains 20 mol% or more of a fatty acid having 5 to 7 carbon atoms.

  Specific examples of fatty acids other than fatty acids having 5 to 7 carbon atoms used in the present invention include fatty acids having 2 to 4 carbon atoms such as acetic acid, propionic acid, butanoic acid and 2-methylpropionic 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-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-tetramethylpentanoic acid, 2,2-diisopropylpropionic acid, etc. Nine fatty acids; C10-20 fatty acids such as decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, oleic acid, etc. Is mentioned.

  In the present invention, when a fatty acid having 5 to 7 carbon atoms and another fatty acid are combined, it is preferable to use a branched fatty acid having 8 to 9 carbon atoms as the fatty acid other than the fatty acid having 5 to 7 carbon atoms. When a C5-7 fatty acid and a C8-9 branched fatty acid are used in combination, a C5-7 fatty acid and a fatty acid other than a C8-9 branched fatty acid are used in combination. Compared to the case, both the lubricity in the presence of the difluoromethane refrigerant and the compatibility with the difluoromethane refrigerant tend to be further improved. Moreover, when using together a C5-C7 fatty acid and a C8-C9 branched fatty acid, the ratio of the C8-C9 branched fatty acid in the fatty acid which comprises dipentaerythritol fatty acid ester is 80 mol% or less. And is 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 C8-C9 branched fatty acid, when using fatty acids other than these fatty acids, it is C5-C7 in the fatty acid which comprises dipentaerythritol fatty acid ester. The sum of the proportion of fatty acids and the proportion of 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 sum of the proportion of the fatty acid having 5 to 7 carbon atoms and the proportion of the branched fatty acid having 8 to 9 carbon atoms is within the above range, lubricity in the presence of the difluoromethane refrigerant and compatibility with the difluoromethane refrigerant Both tend to be compatible at a higher level.

  Among the dipentaerythritol fatty acid esters according to the present invention, those in which the acid component consists only of a fatty acid having 5 to 7 carbon atoms, and those consisting of a fatty acid having 5 to 7 carbon atoms and a branched fatty acid having 8 to 9 carbon atoms, This is particularly preferable in terms of both the lubricity in the presence of the difluoromethane refrigerant and the compatibility with the difluoromethane refrigerant.

  In the present invention, as long as the fatty acid constituting the dipentaerythritol fatty acid ester satisfies the above conditions, the dipentaerythritol fatty acid ester may have a single molecular structure, or two kinds of esters having different molecular structures. A mixture of the above may also be used.

  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 (a)-(c) as the whole fatty acid which comprises an erythritol fatty acid ester.

  As described above, the dipentaerythritol fatty acid ester according to the present invention essentially contains a fatty acid having 5 to 7 carbon atoms, and contains other fatty acids as constituents as necessary. That is, the dipentaerythritol fatty acid ester according to the present invention may contain only one kind of fatty acid as an acid constituent, or may contain two or more kinds of fatty acids having different structures as an acid constituent. The dipentaerythritol fatty acid ester preferably 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 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.

As a preferred example of the acid component constituting the dipentaerythritol fatty acid ester according to the present invention,
Pentanoic acid;
2-methylbutanoic acid;
3-methylbutanoic acid;
Hexanoic acid;
2-methylpentanoic acid;
2-ethylbutanoic acid;
2-ethylpentanoic acid;
2-methylhexanoic acid;
Two 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;
3 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;
4 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;
5 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;
6 types selected from 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 selected from pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic 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-methylpentanoic acid, 2-ethylbutanoic acid, 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-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-ethylhexanoic 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-trimethylhexanoic 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, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-methylpentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-ethylbutanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-ethylpentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-methylhexanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2 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;
2-ethyl and 2-ethyl 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 Hexanoic acid;
2-ethyl and 2-ethyl 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 Hexanoic acid and 3,5,5-trimethylhexanoic acid;
3 types 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;
3-ethyl and 2-ethyl 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 Hexanoic acid;
3-ethyl and 2-ethyl 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 Hexanoic acid and 3,5,5-trimethylhexanoic acid;
4 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;
4-ethyl and 2-ethyl 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 Hexanoic acid;
4-ethyl and 2-ethyl 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 Hexanoic acid and 3,5,5-trimethylhexanoic acid;
5 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;
5-ethyl and 2-ethyl 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 Hexanoic acid;
5-ethyl and 2-ethyl 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 Hexanoic 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;
6 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 and 2-ethyl Hexanoic acid;
6 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 and 2-ethyl Hexanoic acid and 3,5,5-trimethylhexanoic acid;
7 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;
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 and 2-ethyl Hexanoic acid;
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 and 2-ethyl Hexanoic 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, 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, 2-ethylpentanoic acid, 2-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, 2-methylhexanoic acid, 3,5,5-trimethylhexanoic acid and 2 -Ethylhexanoic acid, etc.

  In the refrigerating machine oil of the present invention, the dipentaerythritol fatty acid ester is mainly used as a base oil. As the base oil of the refrigerating machine oil of the present invention, only the dipentaerythritol fatty acid ester may be used alone (that is, the content of the dipentaerythritol fatty acid ester according to the present invention is 100% by mass). In addition to the above-mentioned dipentaerythritol fatty acid ester, other polyol esters and complex esters, esters such as alicyclic dicarboxylic acid esters, polyglycols, polyvinyl ethers, ketones, polyphenyl ethers, silicones, etc. , 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.

  Among the other oxygen-containing synthetic oils described above, particularly preferred are polyol esters other than dipentaerythritol fatty acid esters. 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 an ester of a 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.

Pentanoic acid;
2-methylbutanoic acid;
3-methylbutanoic acid;
Hexanoic acid;
2-methylpentanoic acid;
2-ethylbutanoic acid;
2-ethylpentanoic acid;
2-methylhexanoic acid;
Two 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;
3 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;
4 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;
5 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;
6 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;
7 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;
Pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, hexanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 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-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-ethylhexanoic 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-trimethylhexanoic 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, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-methylpentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-ethylbutanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-ethylpentanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2-methylhexanoic acid, 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid;
2 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;
2-ethyl and 2-ethyl 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 Hexanoic acid;
2-ethyl and 2-ethyl 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 Hexanoic acid and 3,5,5-trimethylhexanoic acid;
3 types 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;
3-ethyl and 2-ethyl 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 Hexanoic acid;
3-ethyl and 2-ethyl 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 Hexanoic acid and 3,5,5-trimethylhexanoic acid;
4 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;
4-ethyl and 2-ethyl 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 Hexanoic acid;
4-ethyl and 2-ethyl 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 Hexanoic acid and 3,5,5-trimethylhexanoic acid;
5 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;
5-ethyl and 2-ethyl 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 Hexanoic acid;
5-ethyl and 2-ethyl 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 Hexanoic 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;
6 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 and 2-ethyl Hexanoic acid;
6 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 and 2-ethyl Hexanoic acid and 3,5,5-trimethylhexanoic acid;
7 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;
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 and 2-ethyl Hexanoic acid;
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 and 2-ethyl Hexanoic 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, 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, 2-ethylpentanoic acid, 2-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, 2-methylhexanoic acid, 3,5,5-trimethylhexanoic acid and 2 -Ethylhexanoic acid.

  In the present invention, the blending amount when other oxygen-containing synthetic oil is blended is not particularly limited as long as it does not impair the excellent lubricity and compatibility of the refrigerating machine oil of the present invention, but a polyol other than dipentaerythritol When blending an ester, it is necessary to be 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, and 70% by mass or less, based on the total amount of refrigerating machine oil. More preferably, it is still more preferably 60% by mass or less, and most preferably 50% by mass or less; when blending oxygen-containing synthetic oil other than polyol ester, it is 50 based on the total amount of refrigerating machine oil. It is necessary to be not more than mass%, preferably not more than 40 mass%, more preferably not more than 30 mass%. 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 refrigerating machine oil of the present invention contains dipentaerythritol ester and, if necessary, other oxygen-containing synthetic oil, and these are mainly used as a base oil. The refrigerating machine oil of the present invention can be suitably used even in a state in which no additive is added (that is, 100% by mass of the base oil), but it can also be used in a form in which various additives are blended as necessary.

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

Among the phosphorus compounds used in the present invention, the phosphate ester includes tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate Phosphate, tritridecyl phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl Diphenyl phosphate, xylenyl diphenyl phosphate, etc .;
Examples of acidic phosphate esters include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate, monododecyl Acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid phosphate, dipentyl acid , Dihexyl reed Dophosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl acid, dipentadecyl acid Hexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, etc .;
As the amine salt of the acidic phosphate ester, the acidic phosphate ester and methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine A salt with an amine such as dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine;
Examples of the chlorinated phosphate ester include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, tris-chlorophenyl phosphate, polyoxyalkylene bis [di (chloroalkyl)] phosphate, and the like.
As phosphites, dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl Phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite Phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite etc .;
Examples of thiophosphates include tributyl phosphorothioate, tripentyl phosphorothioate, trihexyl phosphorothionate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl phosphorothionate, tridecyl phosphorothioate. Phosphorothioate, triundecyl phosphorothioate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothioate, tripentadecyl phosphorothionate, trihexadecyl phosphorothioate, Triheptadecyl phosphorothioate, trioctadecyl phosphorothioate, trioleyl phosphorothioate, triphenyl phosphorothioate, tricres Ruphophosphothioate, Trixylenyl phosphorothioate, Cresyl diphenyl phosphorothioate, Xylenyl diphenyl phosphorothionate, Tris (n-propylphenyl) phosphorothionate, Tris (isopropylphenyl) phosphoro Thionate, tris (n-butylphenyl) phosphorothionate, tris (isobutylphenyl) phosphorothionate, tris (s-butylphenyl) phosphorothionate, tris (t-butylphenyl) phosphorothionate, Is mentioned. In the present invention, one of the above phosphorus compounds may be used alone, or two or more may be used in combination.

  When the above phosphorus compound is blended in the refrigerating machine oil of the present invention, the blending amount is not particularly limited, but usually the content is 0. 0 based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blended additives). It is desirable to blend the phosphorus compound in an amount such that it is 01 to 5.0% by mass, more preferably 0.02 to 3.0% by mass.

  Further, in the refrigerating machine oil of the present invention, in order to further improve the heat and hydrolysis stability, the following (i) to (viii): (i) phenyl glycidyl ether type epoxy compound (ii) alkyl glycidyl ether type epoxy compound (Iii) glycidyl ester type epoxy compound (iv) allyloxirane compound (v) alkyl oxirane compound (vi) alicyclic epoxy compound (vii) epoxidized fatty acid monoester (viii) epoxidized vegetable oil Various epoxy compounds can be blended.

  Specific examples of (i) phenyl glycidyl ether type epoxy compounds 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.

  (Ii) 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 di Examples thereof include glycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, polyalkylene glycol monoglycidyl ether, polyalkylene glycol diglycidyl ether and the like.

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

(In formula (1), the compound represented by R represents a C1-C18 hydrocarbon group) is mentioned.

  In the above formula (1), R represents a hydrocarbon group having 1 to 18 carbon atoms. Examples of such a hydrocarbon group include an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, and carbon. A cycloalkyl group having 5 to 7 carbon atoms, an alkylcycloalkyl group having 6 to 18 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 7 to 18 carbon atoms, an arylalkyl group having 7 to 18 carbon atoms, and the like. Can be mentioned. Among these, an alkylphenyl group having an alkyl group having 5 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, a phenyl group, and an alkyl group having 1 to 4 carbon atoms is preferable.

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

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

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

で表される化合物のように、エポキシ基を構成する炭素原子が直接脂環式環を構成している化合物が挙げられる。 (Vi) As the alicyclic epoxy compound, the following general formula (2):

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

  Specific examples of such alicyclic epoxy compounds include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and bis. (3,4-epoxycyclohexylmethyl) adipate, exo-2,3-epoxynorbornane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (7-oxabicyclo [4.1.0] Hept-3-yl) -spiro (1,3-dioxane-5,3 ′-[7] oxabicyclo [4.1.0] heptane, 4- (1′-methylepoxyethyl) -1,2-epoxy Examples include 2-methylcyclohexane and 4-epoxyethyl-1,2-epoxycyclohexane.

  (Vii) Specific examples of epoxidized fatty acid monoesters include esters of epoxidized fatty acids having 12 to 20 carbon atoms with alcohols or phenols having 1 to 8 carbon atoms and alkylphenols. In particular, butyl, hexyl, benzyl, cyclohexyl, methoxyethyl, octyl, phenyl and butylphenyl esters of epoxy stearate are preferably used.

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

  Among these epoxy compounds, a phenylglycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, an alicyclic epoxy compound, and an epoxidized fatty acid monoester are preferable because the heat and hydrolysis stability can be further improved. An ester type epoxy compound and an alicyclic epoxy compound are more preferable.

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

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

  Furthermore, in order to further enhance the performance of the refrigerating machine oil in the present invention, conventionally known refrigerating machine oil additives such as di-tert-butyl-p-cresol, phenolic antioxidants such as bisphenol A are prevented as necessary. Agents, amine-based antioxidants such as phenyl-α-naphthylamine, N, N-di (2-naphthyl) -p-phenylenediamine, antiwear agents such as zinc dithiophosphate, chlorinated paraffin, sulfur compounds, etc. Pressure agent, oily agent such as fatty acid, defoaming agent such as silicone, metal deactivator such as benzotriazole, viscosity index improver, pour point depressant, detergent dispersant etc. It is also possible to mix and combine them. The total blending amount of these additives is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blending additives).

The volume resistivity of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 1.0 × 10 ¹¹ Ω · cm or more, more preferably 1.0 × 10 ¹² Ω · cm or more, and further preferably 1.0. × 10 ¹³ Ω · cm or more. In particular, when the refrigerating machine oil of the present invention is used in a refrigerating machine equipped with a hermetic refrigerant compressor, high electrical insulation tends to be required. In the present invention, the volume resistivity means a value [Ω · cm] at 25 ° C. measured in accordance with JIS C 2101 “Electrical insulating oil test method”.

  Furthermore, the water content of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 200 ppm or less, more preferably 100 ppm or less, and most preferably 50 ppm or less, based on the total amount of refrigerating machine oil. In particular, when the refrigerating machine oil of the present invention is used in a refrigerating machine equipped with a hermetic refrigerant compressor, the water content may be low from the viewpoint of influence on the heat / hydrolysis stability and electrical insulation of the refrigerating machine oil Desired.

  Furthermore, the total acid value of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 0.1 mgKOH / g or less, more preferably 0.05 mgKOH / g or less. When the total acid value is within the above range, corrosion resistance to metals used in refrigerators or piping tends to be improved. In addition, in this invention, a total acid value represents the value of the total acid value measured based on JISK2501 "Petroleum products and lubricating oil-neutralization number test method".

  Furthermore, the ash content of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 100 ppm or less, more preferably 50 ppm or less. When the ash content is within the above range, the heat / hydrolysis stability is improved and the generation of sludge and the like tends to be suppressed. In the present invention, the ash content refers to the ash value [ppm] measured in accordance with JIS K 2272 “Testing method for ash content and sulfated ash content of crude oil and petroleum products”.

Moreover, kinematic viscosity of the refrigerating machine oil of the present invention is not particularly limited, but is preferably a kinematic viscosity at 40 ° C. is 20~400mm ² / s, more preferably 25~350mm ² / s, and most preferably 30 to 300 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.

  The refrigerating machine oil for difluoromethane refrigerant of the present invention exhibits sufficiently high lubricity and sufficiently high compatibility when used together with difluoromethane refrigerant, and is widely used as a refrigerating machine oil for a refrigerator for difluoromethane refrigerant. can do. Specific examples of refrigerators in which the refrigerating machine oil of the present invention is used include room air conditioners, packaged air conditioners, refrigerators, automotive air conditioners, dehumidifiers, freezers, refrigerated warehouses, vending machines, showcases, chemical plants, etc. Among them, 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 fluid composition for a refrigerator mixed with a difluoromethane refrigerant, as will be described later.

  That is, the fluid composition for a refrigerator of the present invention is characterized by containing the above-described refrigerator oil for a difluoromethane refrigerant of the present invention and a difluoromethane refrigerant. Here, the blending ratio of the refrigerating machine oil and the difluoromethane refrigerant in the fluid composition for a refrigerating machine of the present invention is not particularly limited, but the blending quantity of the refrigerating machine oil is usually 1 to 1000 with respect to 100 parts by weight of difluoromethane. Parts by weight, preferably 2 to 800 parts by weight.

  In addition, in the fluid composition for a refrigerator of the present invention, it is possible to achieve both sufficiently high lubricity and sufficiently high compatibility that were not obtained when using conventional refrigerator oil, When only difluoromethane refrigerant is contained as a refrigerant component, it is most useful, but HFC refrigerants other than difluoromethane refrigerant, fluorine-containing ether refrigerants such as perfluoroethers, non-fluorine-containing ether systems such as dimethyl ether You may contain natural refrigerants, such as a refrigerant | coolant and a carbon dioxide, a hydrocarbon.

  Examples of HFC refrigerants other than the difluoromethane refrigerant used in the present invention 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 Examples thereof include HFC refrigerants such as ethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), or a mixture of two or more thereof.

  Specific examples of the mixed refrigerant of difluoromethane refrigerant (HFC-32) and other HFC refrigerants include, for example, a mixture of HFC-134a / HFC-32 = 60 to 80% by mass / 40 to 20% by mass; HFC- 32 / HFC-125 = 40-70 wt% / 60-30 wt% mixture; HFC-134a / HFC-32 / HFC-125 = 60 wt% / 30 wt% / 10 wt% mixture; HFC-134a / HFC-32 / HFC-125 = 40-70 mass% / 15-35 mass% / 5-40 mass% mixture etc. are mentioned as a preferable example. 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-32 / HFC-125 / HFC-134a = 30/10/60 wt% mixture; HFC- 32 / HFC-125 / HFC-134a = 23/25/52 mass% mixture (R407C); HFC-32 / HFC-125 / HFC-134a = 25/15/60 mass% mixture (R407E); Can be mentioned. Among these, when R410A and R410B are used as refrigerants, the usefulness of the fluid composition for a refrigerator of the present invention is more exhibited.

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

  When the fluid composition for a refrigerator of the present invention contains a refrigerant other than the difluoromethane refrigerant, the content of the refrigerant other than the difluoromethane refrigerant is preferably 70% by mass or less based on the total amount of the refrigerant, and 60% by mass. More preferably, it is more preferably 50% by mass or less. When the content of the refrigerant other than the difluoromethane refrigerant exceeds the upper limit, the global warming potential increases and the refrigeration efficiency tends to decrease.

  Further, in the fluid composition for a refrigerating machine of the present invention, the blending ratio of the refrigerating machine oil for a difluoromethane refrigerant of the present invention and a refrigerant (total of difluoromethane refrigerant and other refrigerants) is not particularly limited, but the difluoro of the present invention The content of the refrigerating machine oil for methane refrigerant is preferably 1 to 500 parts by weight and more preferably 2 to 400 parts by weight with respect to 100 parts by weight of the refrigerant.

  The fluid composition for a refrigerator of the present invention can be suitably used for various difluoromethane refrigerant refrigerators as described above. As a typical configuration of the refrigerant circulation cycle provided in the refrigerator, a compression composition is used. Examples include a machine, a condenser, an expansion mechanism and an evaporator, and optionally a dryer.

  As the compressor, a motor composed of a rotor and a stator in a sealed container for storing refrigerating machine oil, a rotation shaft fitted to the rotor, and a compression connected to the motor via the rotation 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 discharged 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. In addition, as a magnet wire used in the motor unit, an enamel coating having a glass transition temperature of 120 ° C. or higher, for example, a single layer such as polyester, polyesterimide, polyamide and polyamideimide, or a layer having a low glass transition temperature as a lower layer, Those having an enamel coating in which a high layer is composite-coated on the upper layer are preferably used. Examples of the composite enameled wire include polyester imide as a lower layer and polyamide imide as an upper layer (AI / EI), polyester as a lower layer and polyamide imide as an upper layer (AI / PE), and the like. .

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

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

[Examples 1 to 9 and Comparative Examples 1 to 11]
In Examples 1 to 9 and Comparative Examples 1 to 11, sample oils were prepared by blending the base oils 1 to 14 and additives 1 to 4 shown below so as to have the composition ratio shown in Table 1 or Table 2, respectively. did. Tables 1 and 2 show properties of the obtained sample oils (kinematic viscosity at 40 ° C. and 100 ° C., total acid value). Moreover, about the sample oil of Examples 1-9 and Comparative Examples 10-11, the ratio of the C5-C7 fatty acid in the fatty acid which comprises dipentaerythritol fatty acid ester, and the ratio of the C8-C9 branched fatty acid Is also shown.

(Base oil)
Base oil 1: Hexaester of dipentaerythritol and n-pentanoic acid Base oil 2: Hexaester of dipentaerythritol and 2-ethylbutanoic acid Base oil 3: Dipentaerythritol and carboxylic acid mixture (60 mol of n-pentanoic acid) %, 3,5,5-trimethylhexanoic acid 40 mol%) Base oil 4: pentaerythritol and carboxylic acid mixture (n-pentanoic acid 60 mol%, 3,5,5-trimethylhexanoic acid 40 mol%) Base oil 5: Diester of neopentyl glycol and 2-ethylhexanoic acid Base oil 6: Triester of trimethylolpropane and 3,5,5-trimethylhexanoic acid Base oil 7: Pentaerythritol and n- Tetraester with pentanoic acid Base oil 8: Pentaerythritol and carboxylic acid mixture (2 -Tetraester base oil with ethylhexanoic acid 50 mol%, 3,5,5-trimethylhexanoic acid 50 mol%): pentaerythritol and carboxylic acid mixture (2-methylhexanoic acid 70 mol%, 2-ethylpentanoic acid Tetraester base oil 10: tetraester with pentaerythritol and carboxylic acid mixture (53 mol% 2-methylhexanoic acid, 22 mol% 2-ethylpentanoic acid, 25 mol% 2-ethylhexanoic acid) Base oil 11: Tetraester of pentaerythritol and 2-ethylhexanoic acid Base oil 12: Tetraester of pentaerythritol and 3,5,5-trimethylhexanoic acid Base oil 13: Dipentaerythritol and carboxylic acid mixture (2- Ethylhexanoic acid 50 mol%, 3,5,5-trimethylhexanoic acid 50 mol ) Hexaester base oil 14 between: hexa esters of dipentaerythritol with 2-methylpropanoic acid.

(Additive)
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 measured. The results obtained for the sample oils of Examples 1 to 9 are shown in Table 1, and the results obtained for the sample oils of Comparative Examples 1 to 11 are shown in Table 2, respectively. In Tables 1 and 2, “<−40” indicates that phase separation and cloudiness were not observed in the measurement temperature range of this test. In Table 2, “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 system temperature to 100 ° C. and the refrigerant pressure to 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 disc after the 60-minute test were measured. The results obtained for the sample oils of Examples 1 to 9 are shown in Table 1, and the results obtained for the sample oils of Comparative Examples 1 to 11 are shown in Table 2, respectively.

  As is clear from the results shown in Table 1, the sample oils of Examples 1 to 9, which are the refrigerating machine oils of the present invention, have excellent compatibility with the difluoromethane refrigerant and excellent lubricity in the presence of the difluoromethane refrigerant. It was confirmed that there was.

  On the other hand, as shown in Table 2, the sample oils of Comparative Examples 1 to 9 containing no dipentaerythritol fatty acid ester are either compatible with the difluoromethane refrigerant or lubricated in the presence of the difluoromethane refrigerant. Was inferior. Moreover, the sample oils of Comparative Examples 10 and 11 using dipentaerythritol fatty acid ester whose fatty acid ratio is outside the scope of the present invention were inferior in compatibility with the difluoromethane refrigerant.

Claims (3)

Containing 20 mass% or more of an ester of dipentaerythritol and a fatty acid based on the total amount of refrigerating machine oil,
The ratio of the fatty acid having 5 to 7 carbon atoms in the fatty acid constituting the ester is 20 mol% or more, and the fatty acid constituting the ester is a fatty acid having 5 to 7 carbon atoms as the fatty acid having 5 to 7 carbon atoms. Containing at least one selected from the group consisting of linear fatty acids and branched fatty acids having 5 to 7 carbon atoms,
Refrigerating machine oil used together with a refrigerant consisting only of difluoromethane (HFC-32) .   The refrigerating machine oil according to claim 1, further comprising 0.1 to 5.0% by mass of an epoxy compound based on the total amount of the refrigerating machine oil. The fluid composition for refrigerators containing the refrigerating machine oil of Claim 1 or 2, and the refrigerant | coolant which consists only of difluoromethane (HFC-32) .