JP2009079142A - Base oil for refrigerator oil for carbon dioxide coolant, and refrigerator oil for carbon dioxide coolant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base oil excellent in stability and electric insulation property and having appropriate compatibility with a coolant when it is used with the carbon dioxide coolant and further indicating sufficient lubrication property even if the viscosity of the base oil is not increased, and a refrigerator oil. <P>SOLUTION: The base oil and the refrigerator oil contain a complete ester of a carboxylic acid in which a ratio of 14-22C branched type fatty acid is 40-100 mol% and neopentyl polyol, and one kind or more of complete ester selected from the group consisting of (a) a complete ester of an alcohol other than neopentyl polyol and mono-carboxylic acid and (b) a complete ester of mono-alcohol and di-carboxylic acid respectively. They have kinematic viscosity at 40°C of 80 mm<SP>2</SP>/s or higher. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a refrigerating machine oil used in a refrigerating and air-conditioning apparatus in which carbon dioxide (carbon dioxide, CO ₂ ) refrigerant is used, and a base oil used in the refrigerating machine oil.

  Due to the problem of ozone layer destruction in recent years, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon), which have been used as refrigerants in conventional refrigeration equipment, are subject to regulation, and HFC (hydrofluorocarbon) is used as a refrigerant instead. It is being done. However, such HFC refrigerants also have problems such as high global warming ability, and the use of natural refrigerants as alternative refrigerants to replace these fluorocarbon refrigerants has been studied. Among them, carbon dioxide refrigerant is highly recyclable, has a limited impact on the environment, is excellent in terms of safety, and has advantages such as compatibility with oil and mechanical materials and availability. Has been used as a refrigerant for refrigerators and the like. In recent years, its application has been studied as a refrigerant for car air conditioners using an open type compressor or a hermetic type electric compressor.

As a refrigerating machine oil for carbon dioxide refrigerant, the following Patent Document 1 discloses a refrigerating machine oil containing an ester base oil.
JP 2000-104084 A

  However, in the case of the conventional refrigerating machine oil using the above-mentioned conventional ester base oil, the lubricity in the coexistence of the carbon dioxide refrigerant is not necessarily sufficient. The viscosity at the time of dissolution of carbon (hereinafter sometimes referred to as “dissolution viscosity”) is greatly reduced, and the viscosity necessary for lubricating the refrigeration equipment cannot be sufficiently maintained.

  As a method for maintaining the lubricity of the refrigerating machine oil, it is conceivable to maintain the oil film thickness by increasing the viscosity of the base oil. In this method, however, the handling property by using the high viscosity base oil is improved. Decrease and stirring efficiency are problems.

  The present invention has been made in view of such circumstances, and when used together with a carbon dioxide refrigerant, has excellent stability and electrical insulation, and has an appropriate compatibility with the refrigerant, and further a base oil. It is an object of the present invention to provide a carbon dioxide refrigerant refrigerating machine base oil and a carbon dioxide refrigerant refrigerating machine oil that exhibit sufficient lubricity without increasing the viscosity of the carbon dioxide refrigerant.

  In order to achieve the above-mentioned object, the present inventors first examined improvement in lubricity of an ester-based refrigerating machine oil in the presence of a carbon dioxide refrigerant that is considered to be particularly difficult to achieve among the above problems. As a result, such lubricity is not necessarily improved by simply increasing the viscosity of the base oil or suppressing the decrease in the solution viscosity, and the carboxylic acid composition in the ester of the carboxylic acid and the polyhydric alcohol is not reduced. It was found to be an important determinant for lubricity in the presence of carbon refrigerants. And as a result of further examination based on such knowledge, the present inventors obtained an ester of a carboxylic acid having a specific carboxylic acid composition and neopentyl polyol, and an ester of a specific alcohol other than neopentyl polyol. It has been found that the above-mentioned problems can be solved by the combined use, and the present invention has been completed.

That is, the present invention provides a first ester which is a complete ester of a carboxylic acid having a carbon number of 14 to 22 and a branched chain fatty acid of 40 to 100 mol% and neopentyl polyol,
Below (a) and (b):
(A) a complete ester of an alcohol other than neopentyl polyol and a monocarboxylic acid (b) a second ester which is one or more complete esters selected from the group consisting of a complete ester of a monoalcohol and a dicarboxylic acid;
And a base oil for a refrigerating machine oil for carbon dioxide refrigerant (hereinafter, also referred to as “the base oil of the present invention”), which has a kinematic viscosity at 40 ° C. of 80 mm ² / s or more.

  In the base oil of the present invention, the neopentyl polyol constituting the first ester preferably has 2 to 6 hydroxyl groups.

  Moreover, it is preferable that the ratio of the C16-C18 fatty acid to the carboxylic acid which comprises 1st ester is 40-100 mol%.

Moreover, it is preferable that the ratio of the tertiary carbon to the constituent carbon of the carboxylic acid which comprises the 1st ester obtained by a ¹³ C-NMR analysis method is 2 mass% or more.

The kinematic viscosity at 40 ° C. of the first ester is preferably 100 mm ² / s or more.

  The present invention also provides a carbon dioxide refrigerant refrigerating machine oil (hereinafter also referred to as “the refrigerating machine oil of the present invention”) characterized by containing the carbon dioxide refrigerant refrigerating machine base oil of the present invention. .

The refrigerating machine oil of the present invention includes a first ester which is a complete ester of a carboxylic acid having 14 to 22 carbon atoms and a carboxylic acid having a proportion of 40 to 100 mol% and neopentyl polyol,
A second ester which is one or more complete esters selected from the group consisting of (a) and (b) above;
And the kinematic viscosity at 40 ° C. may be 80 mm ² / s or more.

  As described above, according to the present invention, when used together with a carbon dioxide refrigerant, it has excellent stability and electrical insulation, has an appropriate compatibility with the refrigerant, and further does not increase the viscosity of the base oil. It becomes possible to provide a base oil for a refrigerating machine oil for carbon dioxide refrigerant and a refrigerating machine oil for carbon dioxide refrigerant exhibiting sufficient lubricity.

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

  Physical properties of the base oil of the present invention and the refrigerating machine oil of the present invention, the first and second esters contained therein, the specific and preferred embodiments of the base oil and additives other than the first and second esters, and their The blending form is common. Therefore, hereinafter, unless otherwise specified, the description of the refrigerating machine oil of the present invention holds true even if the refrigerating machine oil of the present invention is replaced with the base oil of the present invention.

  In addition, although the refrigerating machine oil of this invention contains the polyol ester concerning this invention by containing the base oil of this invention, the refrigerating machine oil of this invention contains components other than 1st and 2nd ester. If it is, the refrigerating machine oil of the present invention may be prepared in advance using the base oil of the present invention containing the component, or the component may be added separately from the base oil of the present invention. The refrigerating machine oil of the invention may be prepared. For example, the refrigerating machine oil of the present invention may contain a base oil other than the first and second esters, but the base oil other than the first and second esters may be previously contained in the base oil of the present invention. Alternatively, it may be added separately as a base oil not containing the base oil according to the present invention (hereinafter also referred to as “second base oil” for convenience) during the preparation of the refrigerating machine oil of the present invention. Also good. Similarly, the refrigerating machine oil of the present invention can contain various additives. However, the additive may be previously contained in the base oil or the second base oil of the present invention, or the present invention. When preparing the refrigerating machine oil, it may be added separately from the base oil or the second base oil of the present invention. Furthermore, in the base oil of the present invention and the refrigerating machine oil of the present invention, whether the components other than the polyol ester according to the present invention are derived from the base oil, the second base oil or the additive of the present invention. Is not particularly limited.

  The first ester contained in the base oil of the present invention is a complete ester of a carboxylic acid and a neopentyl polyol in which the proportion of branched chain fatty acids having 14 to 22 carbon atoms is 40 to 100 mol%.

  The proportion of the branched chain fatty acid having 14 to 22 carbon atoms in the carboxylic acid constituting the first ester (hereinafter referred to as “constituent carboxylic acid”) is 40 to 100 mol%, preferably 50 to 100 mol%. More preferably, it is 60-100 mol%. When the proportion of the branched chain fatty acid having 14 to 22 carbon atoms is less than 40 mol%, the lubricity in the coexistence of the carbon dioxide refrigerant becomes insufficient.

  Specific examples of the branched chain fatty acid having 14 to 22 carbon atoms include branched chain tetradecanoic acid, branched chain pentadecanoic acid, branched chain hexadecanoic acid, branched chain heptadecanoic acid, branched chain octadecanoic acid, and branched chain type. Nonadecanoic acid, branched-chain icosanoic acid, branched-chain heicosanoic acid, and branched-chain docosanoic acid can be mentioned. Of these, branched hexadecanoic acid and branched octadecanoic acid are preferred.

  In addition, the constituent carboxylic acid of the first ester may contain only the branched chain fatty acid as long as the ratio of the branched chain fatty acid having 14 to 22 carbon atoms satisfies the above conditions, or the branched chain type. It may be a mixture of a fatty acid and a linear fatty acid. Furthermore, the constituent fatty acid of the first ester may contain a branched chain fatty acid other than the branched chain fatty acid having 14 to 22 carbon atoms, an aromatic monocarboxylic acid, and the like. Examples of fatty acids other than branched chain fatty acids having 14 to 22 carbon atoms include straight chain fatty acids having 6 to 24 carbon atoms and branched chain fatty acids having 6 to 13, 23 or 24 carbon atoms. Includes linear or branched hexanoic acid, linear or branched heptanoic acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched chain Decanoic acid, linear or branched undecanoic acid, linear or branched dodecanoic acid, linear or branched tridecanoic acid, linear tetradecanoic acid, linear pentadecanoic acid, linear hexadecanoic acid , Linear heptadecanoic acid, linear octadecanoic acid, linear nonadecanoic acid, linear icosanoic acid, linear heicosanoic acid, linear docosanoic acid, linear or branched tricosanoic acid, linear Or branched chain tetracosanoic acid That. The constituent carboxylic acid of the polyol ester according to the present invention is preferably a monovalent carboxylic acid.

  Further, the carbon number distribution of the constituent carboxylic acid of the first constituent ester is not particularly limited as long as the proportion of the branched chain fatty acid having 14 to 22 carbon atoms satisfies the above condition, but the flow in the presence of a carbon dioxide refrigerant is not limited. From the viewpoint of suitably ensuring the property and lubricity, the proportion of fatty acids having 16 to 18 carbon atoms (including both straight-chain fatty acids and branched-chain fatty acids) is preferably 40 to 100 mol%, more Preferably it is 50-100 mol%, More preferably, it is 60-100 mol%, More preferably, it is 80-100 mol%, Most preferably, it is 90-100 mol%, Most preferably, it is 95-100 mol%. When the proportion of the fatty acid having 16 to 18 carbon atoms is less than 40 mol%, the lubricity in the presence of a carbon dioxide refrigerant tends to be lowered.

  Further, in the first ester, the proportion of the branched fatty acid having 16 to 18 carbon atoms in the constituent carboxylic acid is 40 to 100 mol from the viewpoint of suitably ensuring the fluidity and lubricity in the presence of the carbon dioxide refrigerant. %, More preferably 50 to 100 mol%, still more preferably 60 to 100 mol%, still more preferably 80 to 100 mol%, particularly preferably 90 to 100 mol%, most preferably 95 to 100 mol%. %.

  Furthermore, in the first ester, from the viewpoint of suitably ensuring fluidity and lubricity in the presence of a carbon dioxide refrigerant, the proportion of the branched fatty acid having 18 carbon atoms in the constituent carboxylic acid is 50 to 100 mol%. More preferably, it is 60-100 mol%, More preferably, it is 70-100 mol%.

In the first ester, the proportion of tertiary carbon in the constituent carbon of the constituent carboxylic acid is preferably 5% by mass or more, more preferably 2-12% by mass, and 2.5-5% by mass. % Is more preferable. The ratio of the tertiary carbon can be determined by a ¹³ C-NMR analysis method as the ratio of the integrated value of the tertiary carbon resonance spectrum to the integrated value of the resonance spectrum of all carbon.

  Moreover, as a neopentyl polyol which comprises 1st ester, the neopentyl polyol which has 2-6 hydroxyl groups is used preferably. Examples of neopentyl polyol having 2 to 6 hydroxyl groups include neopentyl glycol, trimethylolpropane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, and di- (pentaerythritol). . Of these, ditrimethylolpropane, pentaerythritol, and di- (pentaerythritol) are preferably used.

  The first ester may be composed of one kind of polyol ester having a single structure, or may be a mixture of two or more kinds of polyol esters having different structures.

  The first ester is a complete ester of one carboxylic acid and one polyhydric alcohol, a complete ester of two or more carboxylic acids and one polyhydric alcohol, one carboxylic acid and 2 Either a complete ester with two or more polyhydric alcohols, or a complete ester with two or more carboxylic acids and two or more polyhydric alcohols may be used. A polyol ester using two or more kinds of carboxylic acids, particularly a polyol ester according to the present invention comprising two or more kinds of carboxylic acids in a complete ester molecule is excellent in low-temperature characteristics and compatibility with a refrigerant.

  The first ester is a complete ester in which all the hydroxyl groups of neopentyl polyol are esterified. However, the base oil of the present invention and the refrigerating machine oil of the present invention have excellent effects due to the first and second esters. As long as it is not spoiled, you may contain the partial ester of the carboxylic acid and neopentyl polyol whose ratio of branched-chain fatty acid is 40-100 mol%. Here, the partial ester means a polyol ester in which part of the hydroxyl group of neopentyl polyol is not esterified and remains as a hydroxyl group. The partial ester is also present as a by-product in the synthesis of the first ester. The purity of the polyol ester according to the present invention obtained by synthesis is defined by the hydroxyl value of the synthesized product, the hydroxyl value is preferably 20 mgKOH / g or less, more preferably 10 mgKOH / g or less, and even more preferably 5 mgKOH / g or less. .

In addition, from the viewpoint of ensuring the kinematic viscosity when the refrigerating machine oil is configured, the kinematic viscosity at 40 ° C. of the first ester is preferably 100 mm ² / s or more, and is 120 to 400 mm ² / s. More preferably, it is more preferably 140 to 300 mm ² / s.

Moreover, the 2nd ester contained in the base oil of this invention is 1 or more types of complete ester chosen from the group which consists of following (a) and (b).
(A) Complete ester of alcohol other than neopentyl polyol and monocarboxylic acid (b) Complete ester of monoalcohol and dicarboxylic acid.

  Regarding the complete ester of (a) above, the monoalcohol specifically includes methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, Examples include pentadecanol. Among these, n-butanol, 2-ethylhexanol, n-decanol, isodecyl alcohol, and isotridecyl alcohol are preferable.

  Moreover, as alcohols other than neopentyl polyol, as diol, specifically, for example, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 2-methyl -1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 3,3-dimethylol Pentane, 2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol 1,11-undecanediol, 1,12-dodecanediol and the like.

  In addition, among alcohols other than neopentyl polyol, specific examples of triol include 1,2,3-propanetriol (glycerol), 1,3,5-pentanetriol, and trimethylol nonane.

  Moreover, as alcohols other than neopentyl polyol, glycerol and polyglycerol (2-trimer of glycerol) are specifically mentioned as glycerol.

  Further, among alcohols other than neopentyl polyol, as saccharides, specifically, xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, Examples include raffinose, gentianose and melezitose.

  Moreover, regarding the complete ester (a), the number of carbon atoms of the monocarboxylic acid is not limited, but those having 2 to 22 carbon atoms are preferably used. Specific examples include linear fatty acids having 2 to 12 carbon atoms or branched fatty acids having 4 to 22 carbon atoms, and in particular, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, Examples include undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, icosanoic acid, and oleic acid. More specifically, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic acid), pelargonic acid (n-nonanoic acid) Capric acid (n-decanoic acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid (3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, 3, 5,5-trimethylhexanoic acid and the like are preferred.

  Further, specific examples and preferred examples of the monoalcohol constituting the complete ester (b) are the same as the monoalcohols exemplified in the description of the complete ester (a), and therefore, redundant description is omitted here. To do. Examples of the dicarboxylic acid include aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, and aromatic dicarboxylic acid. Examples of the aliphatic dicarboxylic acid include maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and the like. Examples of the alicyclic dicarboxylic acid include cyclopentane ring, cyclopentene ring, cyclohexane ring, Examples thereof include dicarboxylic acids such as a cyclohexene ring, a cycloheptane ring, and a cycloheptene ring. Among these, dicarboxylic acids having a cyclohexane ring or a cyclohexene ring are preferable. Specifically, 1,2-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 1-cyclohexene-1,2-dicarboxylic acid, 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl -1,2-cyclohexanedicarboxylic acid, 3-methyl-4-cyclohexene-1,2-dicarboxylic acid, 4-methyl-4-cyclohexene-1,2-dicarboxylic acid; aromatic dicarboxylic acids include phthalates Examples include acid, isophthalic acid, and terephthalic acid.

  The second ester may be composed of one type of single ester of a complete structure, or may be a mixture of two or more types of complete esters having different structures.

  The second ester is a complete ester of one carboxylic acid and one hydroxy compound, a complete ester of two or more carboxylic acids and one hydroxy compound, one carboxylic acid and two or more types Either a complete ester with a hydroxy compound, or a complete ester with two or more carboxylic acids and two or more hydroxy compounds may be used. A complete ester using two or more carboxylic acids, particularly a complete ester comprising two or more carboxylic acids in the molecule is excellent in low-temperature characteristics and compatibility with a refrigerant. Here, “carboxylic acid” includes fatty acid and dicarboxylic acid, and “hydroxy compound” is (a) monoalcohol, diol other than neopentyl polyol, triol other than neopentyl polyol, and glycerins. And saccharides.

  The second ester is a complete ester in which all the hydroxyl groups of the hydroxy compound are esterified. However, when the hydroxy compound constituting the second ester is divalent or higher, or when the carboxylic acid is a dicarboxylic acid. As for the base oil of this invention and the refrigerating machine oil of this invention, as long as the outstanding effect by the 1st and 2nd ester is not impaired, a part of hydroxyl group of the said hydroxy compound is not esterified but remains a hydroxyl group. It means a partial ester remaining or a partial ester in which one of the carboxyl groups of the dicarboxylic acid remains as a carboxyl group without being esterified. The partial ester is also present as a by-product in the synthesis of the first ester. When the hydroxy compound constituting the second ester is divalent or higher, the purity of the complete ester obtained by synthesis is defined by the hydroxyl value of the synthesized product, and the hydroxyl value is preferably 20 mgKOH / g or less, preferably 10 mgKOH / g g or less is more preferable, and 5 mgKOH / g or less is more preferable. Further, when the carboxylic acid constituting the second ester is a dicarboxylic acid, the purity of the complete ester obtained by synthesis is defined by the acid value, and from the viewpoint of suppressing corrosion of the refrigeration equipment, the acid value is preferably Is preferably 0.1 mgKOH / g or less, more preferably 0.05 mgKOH / g or less.

The kinematic viscosity at 40 ° C. of the second ester is not particularly limited, but when the base oil of the present invention is constituted with the first ester, the kinematic viscosity at 40 ° C. of the base oil is 80 mm ² / s or more. It is preferable to select as follows.

  Although the base oil of this invention and the refrigerating machine oil of this invention may consist only of 1st and 2nd ester, you may further contain base oils other than 1st and 2nd ester. Base oils other than the first and second esters include mineral oils, olefin polymers, naphthalene compounds, hydrocarbon oils such as alkylbenzene, and ester base oils other than the first and second esters, polyglycol, polyvinyl Synthetic oils containing oxygen such as ether, ketone, polyphenyl ether, silicone, polysiloxane, perfluoroether may be used in combination. Of the above, polyglycol, polyvinyl ether, and ketone are preferably used as the synthetic oil containing oxygen.

  In the refrigerating machine oil of the present invention, the contents of the first and second esters are not particularly limited. However, the first and second ester contents are excellent in terms of various performances such as lubricity, refrigerant compatibility, thermal / chemical stability, and electrical insulation. And the total content of the second ester is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 99% by mass or more, based on the total amount of the refrigerating machine oil. Mass% is particularly preferred. In addition, the content of the first and second esters in the base oil of the present invention is the content based on the total amount of the refrigerating machine oil of the first and second esters when the base oil is used in the refrigerating machine oil. It is preferable to select so as to satisfy the conditions.

Further, in the base oil of the present invention and the refrigerating machine oil of the present invention, the ratio M _{1 of} the first ester content M ₁ (unit: mass%) and the second ester content M ₂ (mass%). / M ₂ is preferably 1/99 to 99/1, more preferably 10:90 to 99: 1, still more preferably 30:70 to 99: 1, and particularly preferably 50:50 to 99: 1. is there.

  The refrigerating machine oil of the present invention contains the base oil of the present invention, and since the base oil contains the first and second esters, it can be suitably used even in the state where no additive is added. However, it can also be used in the form of blending various additives as required.

  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, thiophosphoric acid ester, amine salt of acidic phosphoric acid ester, chlorinated phosphoric acid ester and phosphorous 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.

  Specifically, for example, as phosphate ester, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl Phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xyl Examples include rhenyl diphenyl phosphate.

  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 Examples include hexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate, and the like.

  Examples of thiophosphates include tributyl phosphorothioate, tripentyl phosphorothioate, trihexyl phosphorothioate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl phosphorothionate, tridecyl phosphorothioate. 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 acidic phosphate ester include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, Examples thereof include salts with amines 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 and the like can be mentioned. A mixture of these can also be used.

  When the refrigerating machine oil of the present invention contains the above phosphorus compound, the content of the phosphorus compound is not particularly limited, but is 0.01 to 5.5 based on the total amount of refrigerating machine oil (based on the total amount of base oil and all blended additives). The content is preferably 0% by mass, and 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.

  Further, the refrigerating machine oil of the present invention has a phenyl glycidyl ether type epoxy compound, an alkyl glycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, an allyl oxirane compound, an alkyl oxirane compound, an alicyclic type, in order to further improve its stability. It can contain at least one epoxy compound selected from epoxy compounds, epoxidized fatty acid monoesters and epoxidized vegetable oils.

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

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

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

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

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

  Specific examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and bis (3,4 -Epoxycyclohexylmethyl) adipate, exo-2,3-epoxynorbornane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (7-oxabicyclo [4.1.0] hept-3- Yl) -spiro (1,3-dioxane-5,3 ′-[7] oxabicyclo [4.1.0] heptane, 4- (1′-methylepoxyethyl) -1,2-epoxy-2-methyl Examples include cyclohexane and 4-epoxyethyl-1,2-epoxycyclohexane.

  Specific examples of the epoxidized fatty acid monoester include an ester 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, butylphenyl glycidyl ether, alkyl glycidyl esters or mixtures thereof are particularly preferred.

  When the refrigerating machine oil of the present invention contains the epoxy compound, the content of the epoxy compound is not particularly limited, but is preferably 0.1 to 5.0% by mass based on the total amount of the refrigerating machine oil, 0.2 to More preferably, it is 2.0 mass%. In addition, the said epoxy compound may be used individually by 1 type, and may use 2 or more types together.

  Furthermore, the refrigerating machine oil of the present invention can contain conventionally known refrigerating machine oil additives as necessary in order to further enhance its 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.

The kinematic viscosity at 40 ° C. of the refrigerating machine oil of the present invention is preferably 80 to 1000 mm ² / s, more preferably 80 to 500 mm ² / s, and most preferably 80 to 400 mm ² / s. The kinematic viscosity at 100 ° C. is preferably 1 to 100 mm ² / s, more preferably 5 to 50 mm ² / s.

  Further, the volume resistivity of the refrigerating machine oil of the present invention is not particularly limited, but is preferably 0.01 TΩ · cm or more, more preferably 0.1 TΩ · cm or more, and most preferably 1.0 TΩ · 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 based on JIS C 2101 “Electrical insulating oil test method”.

  Further, the water content of the refrigerating machine oil of the present invention is not particularly limited, but can be 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 it is used for a hermetic refrigerator, it is required to have a low water content from the viewpoint of the effect on oil stability and electrical insulation.

  Further, the acid value of the refrigerating machine oil of the present invention is not particularly limited, but it prevents the corrosion of the metal used in the refrigerating machine or piping, and prevents the decomposition of the ester oil contained in the refrigerating machine oil of the present invention. Therefore, it is preferably 0.1 mgKOH / g or less, more preferably 0.05 mgKOH / g or less. In addition, in this invention, an acid value means the acid value measured based on JISK 2501 "Petroleum products and lubricating oil-neutralization number test method".

  Further, the ash content of the refrigerating machine oil of the present invention is not particularly limited. However, in order to enhance the stability of the refrigerating machine oil of the present invention and suppress the generation of sludge and the like, the ash content is preferably 100 ppm or less, more preferably 50 ppm or less. In the present invention, ash means the value of ash measured based on JISK 2272 “Testing method for ash and sulfated ash of crude oil and petroleum products”.

  The refrigerating machine oil of the present invention exhibits an excellent effect when used together with a carbon dioxide refrigerant. However, the refrigerant used may be a carbon dioxide refrigerant alone, or a carbon dioxide refrigerant and other refrigerants. It may be a mixed refrigerant with a refrigerant. Examples of other refrigerants include HFC refrigerants, fluorine-containing ether refrigerants such as bar fluoroethers, dimethyl ether, ammonia, and hydrocarbons.

  Examples of the HFC refrigerant include hydrofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms. Specifically, for example, difluoromethane (HFC-32), trifluoromethane (HFC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1, HFC such as 1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), or two or more thereof And the like. These refrigerants are appropriately selected depending on the application and required performance. For example, HFC-32 alone; HFC-23 alone; HFC-134a alone; HFC-125 alone; HFC-134a / HFC-32 = 60 to 80 mass % / 40-20 mass% mixture; HFC-32 / HFC-125 = 40-70 mass% / 60-30 mass% mixture; HFC-125 / HFC-143a = 40-60 mass% / 60-40 mass % Mixture; HFC-134a / HFC-32 / HFC-125 = 60 wt% / 30 wt% / 10 wt% mixture; HFC-134a / HFC-32 / HFC-125 = 40-70 wt% / 15- 35 mass% / 5 to 40 mass% mixture; HFC-125 / HFC-134a / HFC-143a = 35-55 mass% / 1-15 mass% / 40-60 mass 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.

  Specific examples of the fluorinated ether refrigerant include HFE-134p, HFE-245mc, HFE-236mf, HFE-236me, HFE-338mcf, HFE-365mcf, HFE-245mf, HFE-347mmy, HFE-347mcc, and HFE. -125, HFE-143m, HFE-227me and the like.

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

  The mixing ratio of carbon dioxide refrigerant and HFC refrigerant, fluorine-containing ether refrigerant, dimethyl ether and ammonia is not particularly limited, but the total amount of refrigerant used in combination with carbon dioxide refrigerant is preferably 1 with respect to 100 parts by mass of carbon dioxide. -200 mass parts, More preferably, it is 10-100 mass parts. As a preferred embodiment, the carbon dioxide refrigerant and the hydrofluorocarbon and / or hydrocarbon are preferably 1 to 200 parts by mass, more preferably 10 to 10 parts by mass as the total amount of the hydrofluorocarbon and hydrocarbon with respect to 100 parts by mass of carbon dioxide. The mixed refrigerant | coolant which mix | blended 100 mass parts is mentioned.

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

  The refrigerating machine oil of the present invention is preferably used in room air conditioners, packaged air conditioners and refrigerators having reciprocating or rotating hermetic compressors because of their excellent electrical characteristics and low hygroscopicity. Moreover, the refrigerating machine oil of the present invention is preferably used for cooling devices for automobile air conditioners, dehumidifiers, water heaters, freezers, refrigerated warehouses, vending machines, showcases, chemical plants, and the like. Furthermore, the refrigerating machine oil of the present invention is also preferably used for those having a centrifugal compressor.

  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.

[Composition of carboxylic acids A and B]
Table 1 shows the acid composition of carboxylic acid A (isostearic acid 873, manufactured by Yuka Kognis Co., Ltd.) and carboxylic acid B (PRISORINE 3501, manufactured by Unikema Co., Ltd.) used in the following examples.

[Examples 1 to 15, Comparative Examples 1 and 2, Reference Example 1]
In Examples 1 to 15 and Comparative Examples 1 and 2, base oils consisting of ester I and ester II shown in Tables 2 to 4 were prepared. In Reference Example 1, a base oil composed of ester I shown in Table 4 was prepared. The esters I and II in each example and comparative example are all complete esters. Tables 2 to 4 show the kinematic viscosities of the obtained base oil at 40 ° C and 100 ° C.

  In Tables 2 to 4, “PET” in the column of “Alcohol composition ratio” of “Ester I” means pentaerythritol, and “DiPET” means dipentaerythritol. In Tables 2 to 4, in the column of “carboxylic acid composition” of “Ester I” and “Ester II”, a linear fatty acid having m carbon atoms is an nCm acid, and a branched fatty acid having m carbon atoms is iCm. Shown as acid. For example, “nC8 acid” means a straight chain fatty acid having 8 carbon atoms, and “iC9 acid” means a branched chain fatty acid having 9 carbon atoms. In the same column, “2EH acid” means 2-ethylhexanoic acid. In Tables 2 to 4, in the column of “Alcohol Composition Ratio” of “Ester II”, a linear alcohol having m carbon atoms is shown as nCm alcohol. For example, “nC4 alcohol” means a linear alcohol having 4 carbon atoms (ie, n-butanol). In the same column, “2EH alcohol” means 2-ethylhexyl alcohol.

  Next, each base oil obtained in Examples 1 to 15, Comparative Examples 1 and 2, and Reference Example 1 was used as a refrigerating machine oil, and the following evaluation tests were performed.

(Refrigerant compatibility)
Based on “Testing compatibility with refrigerant” in JIS-K-2211 “Refrigerator oil”, 2 g of refrigerating machine oil is blended with 2 g of carbon dioxide refrigerant. Whether it was dissolved or not was evaluated as “compatible”, “white turbidity”, and “separation”. The obtained results are shown in Tables 2 to 4.

(Refrigerant melt viscosity)
The apparatus shown in FIG. 1 includes a pressure vessel 5 (made of stainless steel, internal volume: 200 ml) having a viscometer 1, a pressure gauge 2, a thermocouple 3, and a stirrer 4, and a constant temperature for controlling the temperature in the pressure vessel 5. A tank 6 and a sampling cylinder 8 provided with a valve and connected to the pressure vessel 5 through a flow path 7 are provided. The sampling cylinder 8 and the flow path 7 are detachable, and the sampling cylinder 8 measures its weight after vacuum degassing or after weighing a mixture of carbon dioxide refrigerant and refrigerating machine oil. It is possible to do. The thermocouple 3 and the thermostatic chamber 6 are electrically connected to temperature control means (not shown), respectively, and sample oil (or a mixture of carbon dioxide refrigerant and refrigerating machine oil) is transferred from the thermocouple 3 to the temperature control means. A data signal relating to the temperature of the refrigerant is sent, and a control signal is sent from the temperature control means to the thermostat 6 to control the temperature of the refrigerating machine oil or the mixture. Furthermore, the viscometer 1 is electrically connected to an information processing device (not shown), and measurement data relating to the viscosity of the liquid in the pressure vessel 5 is sent from the viscometer 1 to the information processing device, and a predetermined condition is obtained. It is possible to measure the viscosity below.

  In this test, first, 100 g of refrigerating machine oil was put in the pressure vessel 5 and the inside of the vessel was vacuum degassed. Then, a carbon dioxide refrigerant was introduced, and the mixture of the carbon dioxide refrigerant and the refrigerating machine oil was stirred with the stirrer 4. And it adjusted so that it might become 5MPa at 40 degreeC, removing a refrigerant | coolant. After stabilization, the viscosity of the mixture of carbon dioxide refrigerant and refrigeration oil was measured. The measurement result of the refrigerant | coolant melt viscosity in 40 degreeC obtained is shown to Tables 2-4.

(Electrical insulation (volume resistivity))
Based on JIS-C-2101 “Electrical Insulating Oil Test Method”, volume resistivity of refrigerating machine oil at 25 ° C. was measured. The obtained results are shown in Tables 2-4.

(Thermal stability (acid value))
In an autoclave, 90 g of refrigerating machine oil, 10 g of carbon dioxide refrigerant and a catalyst (iron, copper, and aluminum wires) were sealed, and then heated to 200 ° C. and held for 2 weeks. The acid value of the refrigerator oil after 2 weeks was measured. The obtained results are shown in Tables 2-4.

(Lubricity (Abrasion amount))
Based on ASTM D 2670 “FALEXWEAR TEST”, the running-in operation was performed for 1 minute under a load of 150 lb under the condition of the temperature of the refrigerator oil of 100 ° C. Next, the test machine was operated for 2 hours under a load of 250 lb while blowing carbon dioxide refrigerant 10 L / h, and the amount of wear of the test journal (pin) after the test was measured. The obtained results are shown in Tables 2-4.

  As is clear from the results shown in Tables 2 to 4, the refrigerating machine oils of Examples 1 to 15 were lubricated, refrigerant compatible, thermal stability, electrical insulating properties and dynamics when used with a carbon dioxide refrigerant. It can be seen that all the properties of viscosity are excellent in a well-balanced manner. In particular, it can be seen that the refrigerating machine oils of Examples 1 to 8 are superior in lubricity in the coexistence of carbon dioxide refrigerant as compared with the refrigerating machine oil of the comparative example having the same refrigerant dissolution viscosity at 40 ° C. .

It is a schematic block diagram which shows the refrigerant | coolant melt viscosity measuring apparatus used in the Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Viscometer, 2 ... Pressure gauge, 3 ... Thermocouple, 4 ... Stirrer, 5 ... Pressure vessel, 6 ... Constant temperature bath, 7 ... Flow path, 8 ... Sampling cylinder.

Claims (7)

A first ester which is a complete ester of a carboxylic acid and a neopentyl polyol, wherein the proportion of the branched chain fatty acid having 14 to 22 carbon atoms is 40 to 100 mol%;
Below (a) and (b):
(A) a complete ester of an alcohol other than neopentyl polyol and a monocarboxylic acid (b) a second ester which is one or more complete esters selected from the group consisting of a complete ester of a monoalcohol and a dicarboxylic acid;
And a kinematic viscosity at 40 ° C. of 80 mm ² / s or more, a base oil for a refrigerating machine oil for carbon dioxide refrigerant.   The base oil for refrigerating machine oil for carbon dioxide refrigerant according to claim 1, wherein the neopentyl polyol constituting the first ester has 2 to 6 hydroxyl groups.   The refrigerating machine oil for carbon dioxide refrigerant according to claim 1 or 2, wherein the proportion of the fatty acid having 16 to 18 carbon atoms in the carboxylic acid constituting the first ester is 40 to 100 mol%. Base oil for use. The ratio of tertiary carbon to the constituent carbon of the carboxylic acid constituting the first ester obtained by ¹³ C-NMR analysis is 2% by mass or more. Base oil for refrigeration oil for carbon dioxide refrigerant. Wherein the kinematic viscosity at 40 ° C. of the first ester is 100 mm 2 / ^s or more, carbon dioxide refrigerant refrigeration machine oil base oil according to any one of claims 1-4.   A refrigerating machine oil for carbon dioxide refrigerant comprising the base oil for refrigerating machine oil for carbon dioxide refrigerant according to any one of claims 1 to 5. A first ester which is a complete ester of a carboxylic acid and a neopentyl polyol, wherein the proportion of the branched chain fatty acid having 14 to 22 carbon atoms is 40 to 100 mol%;
Below (a) and (b):
(A) a complete ester of an alcohol other than neopentyl polyol and a monocarboxylic acid (b) a second ester that is one or more complete esters selected from the group consisting of a complete ester of a monoalcohol and a dicarboxylic acid;
And a kinematic viscosity at 40 ° C. of 80 mm ² / s or more.

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