JP2010090284A - Refrigerating machine oil for hydrocarbon refrigerant, and working fluid composition for refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating machine oil for hydrocarbon refrigerants and a working fluid composition for refrigerators enabling the coexistence of the reduction in viscosity with the maintenance of refrigerant-dissolved viscosity and the coexistence of refrigerant compatibility of the refrigerating machine oil with the maintenance of refrigerant-dissolved viscosity. <P>SOLUTION: The refrigerating machine oil for hydrocarbon refrigerants contains an ester of a polyhydric alcohol and a fatty acid in which the proportion of a 10-22C straight fatty acid is 50-100 mol%. The working fluid composition for refrigerators contains the ester and a hydrocarbon refrigerant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigerating machine oil and a working fluid composition for a refrigerating machine used in a refrigerating and air-conditioning apparatus in which a hydrocarbon refrigerant is used.

  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 and air-conditioning equipment, are subject to regulation, and HFC (hydrofluorocarbon) as a refrigerant instead. It is being used. However, some HFCs have a high GWP (Global Warming Potential), and HFCs are also being regulated from the viewpoint of recent warming prevention measures. Therefore, the use of a refrigerant having a low GWP has been studied, and among them, hydrocarbon refrigerants that have been used in the past have been reviewed.

As refrigeration oils for hydrocarbon refrigerants, naphthenic or paraffinic mineral oils, alkylbenzene oils, ether oils, ester oils, mixed oils of mineral oils and esters have been proposed (see Patent Documents 1 to 6).
JP-A-8-170586 JP-A-9-324187 JP-A-10-158667 JP 2000-119671 A JP 2002-194369 A Japanese Patent Laid-Open No. 2003-041278

  In recent years, with increasing interest in energy conservation in various fields, energy conservation measures such as improving thermal efficiency and reducing power consumption are also being studied in the field of refrigeration and air conditioning equipment.

  As means for contributing to energy saving measures from the refrigeration oil side, it is conceivable to improve the energy efficiency by reducing the viscosity of the refrigeration oil and reduce the stirring resistance in the refrigerant compressor. However, the actual situation is that sufficient studies have not yet been made on reducing the viscosity of hydrocarbon refrigerants.

  Refrigeration oil is used in the presence of a refrigerant, and therefore the usage environment is significantly different from other lubricating oils used in an air atmosphere or the like. This is one of the reasons why the technology for reducing viscosity in other lubricating oil fields cannot be applied to refrigeration oil as it is. That is, from the viewpoint of improving energy efficiency and reducing stirring resistance, it is desirable that the refrigerating machine oil has a low kinematic viscosity, but when the refrigerating machine oil is simply reduced in viscosity, the refrigerant dissolves in the refrigerating machine oil in the refrigerating system. The viscosity (refrigerant dissolution viscosity) of the fluid composition, which is a mixture of refrigeration oil and refrigerant, is greatly reduced, and there are concerns about problems such as blow-through and poor lubrication in the compression section of the refrigerant compressor.

  On the other hand, in the refrigerant circulation system of the refrigerating and air-conditioning equipment, due to the mechanism, a part of the refrigerating machine oil in the refrigerant compressor is discharged together with the refrigerant to the circulation flow path. Here, in order to prevent poor lubrication due to an insufficient amount of refrigerating machine oil in the refrigerant compressor, it is important that the discharged refrigerating machine oil returns to the refrigerant compressor through the circulation channel (oil returnability). Become. In general, the refrigerating machine oil having better refrigerant compatibility is more excellent in oil return, whereas the refrigerant dissolution viscosity tends to be lowered.

  As described above, it is very difficult to achieve both the reduction of the viscosity of the refrigerating machine oil and the maintenance of the refrigerant dissolution viscosity, or the compatibility of the refrigerant compatibility of the refrigerating machine oil and the maintenance of the refrigerant dissolution viscosity. In this respect, the conventional refrigerant refrigerant for hydrocarbon refrigerant still has room for improvement.

  The present invention has been made in view of such a situation, and the purpose thereof is to achieve both a reduction in viscosity and maintenance of the refrigerant dissolution viscosity, and a compatibility between maintenance of refrigerant compatibility of refrigerant oil and refrigerant dissolution viscosity. An object is to provide a refrigerating machine oil for a hydrocarbon refrigerant and a working fluid composition for a refrigerating machine.

  As a result of intensive studies to achieve the above object, the present inventors have solved the above problems by using a fatty acid having a specific fatty acid composition as a constituent fatty acid of an ester and a polyhydric alcohol as a constituent alcohol. As a result, the present invention has been completed.

  That is, the refrigerating machine oil for hydrocarbon refrigerant of the present invention is an ester of a fatty acid and a polyhydric alcohol in which the proportion of linear fatty acid having 10 to 22 carbon atoms is 50 to 100 mol% (hereinafter referred to as “ester according to the present invention”). It is also characterized by containing.

  Since the refrigerating machine oil for hydrocarbon refrigerants of the present invention has the above-described configuration, it is possible to achieve both a reduction in viscosity of the refrigerating machine oil having a contradictory relationship and maintenance of the refrigerant dissolution viscosity, and refrigerant compatibility and refrigerant dissolution. Both maintenance of viscosity can be achieved. Therefore, by using the refrigeration oil for hydrocarbon refrigerant of the present invention, the refrigerant gas sealability at the sliding portion of the refrigerant compressor, the lubricity at the sliding portion, and the energy efficiency of the refrigerant compressor are all achieved at a high level. As a result, it is possible to achieve both energy saving and high reliability of the refrigerating and air-conditioning equipment.

  Moreover, the refrigerating machine oil for hydrocarbon refrigerants of the present invention contains an ester of a fatty acid in which the ratio of the branched fatty acid having 10 to 22 carbon atoms is 50 to 100 mol and a polyhydric alcohol having 2 to 6 hydroxyl groups. It is preferable to do. The polyhydric alcohol having 2 to 6 hydroxyl groups is selected from neopentyl glycol, trimethylolpropane, pentaerythritol, di- (trimethylolpropane), tri- (trimethylolpropane) and di- (pentaerythritol). It is preferable that it is 1 type or 2 types or more.

  Moreover, the working fluid composition for refrigerators of this invention contains the ester of the fatty acid and polyhydric alcohol whose ratio of a C10-C22 linear fatty acid is 50-100 mol%, and a hydrocarbon refrigerant. It is characterized by that.

  As described above, according to the present invention, there is provided a refrigerating machine oil for hydrocarbon refrigerant that can achieve both a reduction in viscosity and maintenance of refrigerant dissolution viscosity, and compatibility of refrigerant compatibility of refrigerant oil and maintenance of refrigerant dissolution viscosity. The

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

  The refrigerating machine oil for hydrocarbon refrigerant of the present invention contains an ester of a fatty acid and a polyhydric alcohol in which the proportion of the linear fatty acid having 10 to 22 carbon atoms is 50 to 100 mol%.

The proportion of the linear fatty acid having 10 to 22 carbon atoms in the fatty acid (hereinafter referred to as “constituent fatty acid”) constituting the ester according to the present invention is 50 to 100 mol%, preferably 60 to 100, as described above. It is mol%, More preferably, it is 70-100 mol%. When the proportion of the linear fatty acid having 10 to 22 carbon atoms is less than 50 mol%, the lubricity in the presence of the hydrocarbon refrigerant becomes insufficient. The linear fatty acid having 10 to 22 carbon atoms may be saturated or unsaturated, and specifically includes, for example, decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecane. Acid (myristic acid), pentadecanoic acid, hexadecanoic acid (palmitic acid), heptadecanoic acid, octadecanoic acid (stearic acid), nonadecanoic acid, icosanoic acid (arachidic acid), heicosanoic acid, docosanoic acid (behenic acid), obtucilic acid, isodesenoin Acid, caproleic acid, hendesonic acid, lindelic acid, lauroleic acid, tuzuic acid, fiseteric acid, myristoleic acid, palmitooleic acid, heptadecenylene acid, petroceledic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid , Linoleic acid, hiragonic acid, linole Acid, arachidonic acid, eicosapentaenoic acid, etc. docosahexaenoic acid. Among them capric acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid.

Further, the constituent fatty acid may contain only a linear fatty acid or a mixture of a linear fatty acid and a branched fatty acid as long as the proportion of the linear fatty acid having 10 to 22 carbon atoms satisfies the above conditions. May be. Furthermore, the constituent fatty acid may contain a branched fatty acid other than the branched fatty acid having 10 to 20 carbon atoms.

Examples of fatty acids other than the linear fatty acids having 10 to 22 carbon atoms include branched fatty acids having 6 to 22 carbon atoms and linear fatty acids having 6 to 9 carbon atoms, and more specifically, linear or branched fatty acids. Hexanoic acid, linear or branched heptanoic acid, linear or branched octanoic acid, linear or branched nonanoic acid, branched decanoic acid, branched undecanoic acid, branched Dodecanoic acid, branched tridecanoic acid, branched tetradecanoic acid, branched pentadecanoic acid, branched hexadecanoic acid, branched heptadecanoic acid, branched octadecanoic acid, branched nonadecanoic acid, branched eicosanoic acid Branched heicosanoic acid, branched docosanoic acid and the like.

  In addition, the carbon number distribution of the constituent fatty acids is not particularly limited as long as the ratio of the linear fatty acids having 10 to 22 carbon atoms satisfies the above conditions, but preferably ensures fluidity and lubricity in the presence of a hydrocarbon refrigerant. From the viewpoint of, the proportion of fatty acids having 12 to 18 carbon atoms (including both straight-chain fatty acids and branched fatty acids) is preferably 40 to 100 mol%, more preferably 50 to 100 mol%, still more preferably. It is 60 to 100 mol%, more preferably 80 to 100 mol%, particularly preferably 90 to 100 mol%, and most preferably 95 to 100 mol%. When the proportion of the fatty acid having 12 to 18 carbon atoms is less than 40 mol%, the lubricity in the presence of the hydrocarbon refrigerant tends to be lowered.

  Furthermore, in the ester according to the present invention, the proportion of the linear saturated fatty acid having 10 to 22 carbon atoms in the constituent fatty acid is 80 from the viewpoint of suitably ensuring fluidity and lubricity in the presence of a hydrocarbon refrigerant. It is preferably at most mol%, more preferably at most 60 mol%, still more preferably at most 40 mol%.

  Moreover, as a polyhydric alcohol which comprises the ester concerning this invention, the polyhydric alcohol which has 2-6 hydroxyl groups is used preferably. From the viewpoint of obtaining a high level of lubricity in the presence of a hydrocarbon refrigerant, it is preferable to use a polyhydric alcohol having 4 to 6 hydroxyl groups, and a high level of energy efficiency in the presence of a hydrocarbon refrigerant. From the viewpoint of obtaining, it is preferable to use a polyhydric alcohol having 2 or 3 hydroxyl groups.

  Specific examples of the dihydric alcohol (diol) include ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, and 2-methyl-1,3-propane. Diol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 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, Examples thereof include 12-dodecanediol. Specific examples of trihydric or higher alcohols include trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, di- ( Pentaerythritol), tri- (pentaerythritol), glycerin, polyglycerin (glycerin 2-3 trimer), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol And polyhydric alcohols such as xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, and cellobiose. Among these, hindered such as neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, di- (pentaerythritol), etc. Alcohol is preferred.

  Since the ester according to the present invention is more excellent in hydrolytic stability, neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), More preferred are hindered alcohol complete esters such as pentaerythritol, di- (pentaerythritol), tri- (pentaerythritol), neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane and pentaerythritol complete esters. Even more preferable, neopentyl glycol, trimethylolpropane and complete ester of pentaerythritol are particularly preferable, and particularly excellent in compatibility with the refrigerant and hydrolytic stability. Complete esters of Luo pentaerythritol is most preferred.

  The ester according to the present invention may be composed of one kind of ester having a single structure, or may be a mixture of two or more kinds of esters having different structures.

  The ester according to the present invention is a complete ester of one fatty acid and one polyhydric alcohol, a complete ester of two or more fatty acids and one polyhydric alcohol, one fatty acid and two or more. Any of complete esters of polyhydric alcohols, and complete esters of two or more fatty acids and two or more polyhydric alcohols may be used. Among these, esters using mixed fatty acids, particularly polyol esters composed of two or more fatty acids in a complete ester molecule, are excellent in low-temperature characteristics and compatibility with refrigerants.

  Note that the refrigerating machine oil for hydrocarbon refrigerant of the present invention is not limited to fatty acids having a ratio of branched fatty acids having 14 to 20 carbon atoms of 40 to 100 mol%, as long as the excellent effects of the ester according to the present invention are not impaired. You may contain the partial ester with a monohydric alcohol. Here, the partial ester means an ester in which a part of the hydroxyl acid of the polyhydric alcohol remains as a hydroxyl group without being esterified. The partial ester is also present as a by-product when the ester according to the present invention is synthesized. The purity of the 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.

  The refrigerating machine oil for hydrocarbon refrigerant of the present invention may consist only of the ester according to the present invention, but may further contain a base oil other than the ester according to the present invention. Examples of base oils other than esters according to the present invention include mineral oils, olefin polymers, naphthalene compounds, hydrocarbon oils such as alkylbenzenes, and ester base oils other than esters according to the present invention (monoesters, linear as constituent fatty acids) Polyol esters containing only fatty acids, etc.), synthetic oils containing oxygen such as polyglycols, polyvinyl ethers, ketones, polyphenyl ethers, silicones, polysiloxanes and perfluoroethers may be used in combination. Among the above, esters, polyglycols, and polyvinyl ethers are preferably used as the synthetic oil containing oxygen.

  In the refrigerating machine oil for hydrocarbon refrigerant of the present invention, the ester content according to the present invention is not particularly limited, but is excellent in various performances such as energy efficiency, lubricity, refrigerant compatibility, thermal / chemical stability, and electrical insulation. In terms of the total amount of refrigerating machine oil, it is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, still more preferably 40% by mass or more, and particularly preferably 50% by mass or more. Further, the content of the complete ester in the refrigerant refrigerant for hydrocarbon refrigerant of the present invention is preferably selected so that the content of the ester according to the present invention based on the total amount of the refrigerating machine oil satisfies the above conditions.

  Moreover, the refrigerating machine oil for hydrocarbon refrigerants of the present invention can be used in a form in which various additives are blended as required.

  In order to further improve the wear resistance and load bearing capacity of the refrigerating machine oil for hydrocarbon refrigerant 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 at least one phosphorus compound selected from the group consisting of phosphites can be blended. These phosphorus compounds are esters of phosphoric acid or phosphorous acid with alkanols and polyether type alcohols or derivatives thereof.

  Specifically, for example, as phosphate ester, 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. Mixtures of these can also be used.

  When the refrigerating machine oil for hydrocarbon refrigerants of the present invention contains the above phosphorus compound, the content of the phosphorus compound is not particularly limited, but it is 0.00 on the basis of the total quantity of refrigerating machine oil (based on the total quantity of base oil and all blended additives). The content is preferably 01 to 5.0 mass%, more preferably 0.02 to 3.0 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 for hydrocarbon refrigerant 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, and an alkyl oxirane compound in order to further improve its stability. , At least one epoxy compound selected from alicyclic 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. As used herein, the alkylphenyl glycidyl ether includes those having 1 to 3 alkyl groups having 1 to 13 carbon atoms, and those having one alkyl group having 4 to 10 carbon atoms, such as n-butylphenyl glycidyl. Ether, i-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, pentylphenyl glycidyl ether, hexylphenyl glycidyl ether, heptylphenyl glycidyl ether, octylphenyl glycidyl ether, nonylphenyl glycidyl ether, decylphenyl A glycidyl ether etc. can be illustrated as a preferable thing.

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

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

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

  Among these epoxy compounds, phenyl glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, alicyclic epoxy compounds and epoxidized fatty acid monoesters are preferred. Of these, phenyl glycidyl ether type epoxy compounds and glycidyl ester type epoxy compounds are more preferred, and phenyl glycidyl ether, butylphenyl glycidyl ether, alkyl glycidyl esters or mixtures thereof are particularly preferred.

  When the refrigeration oil for hydrocarbon refrigerant 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 refrigeration oil, More preferably, it is 0.2-2.0 mass%. In addition, the said epoxy compound may be used individually by 1 type, and may use 2 or more types together.

  Furthermore, the refrigerating machine oil for hydrocarbon refrigerants 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 of the refrigerating machine oil for hydrocarbon refrigerant of the present invention is not particularly limited, but the kinematic viscosity at 40 ° C. is preferably 3 to 1000 mm ² / s, more preferably 4 to 500 mm ² / s, and most preferably 5 to 400 mm. ² / s. The kinematic viscosity at 100 ° C. is preferably 1 to 100 mm ² / s, more preferably ² to 50 mm ² / s.

Further, the volume resistivity of the refrigerating machine oil for hydrocarbon refrigerant of the present invention is not particularly limited, but is preferably 1.0 × 10 ¹² Ω · cm or more, more preferably 1.0 × 10 ¹³ Ω · cm or more, most preferably. May be 1.0 × 10 ¹⁴ Ω · cm or more. In particular, when it is used for a hermetic refrigerator, high electrical insulation tends to be required. In the present invention, the volume resistivity means a value at 25 ° C. measured based on JIS C 2101 “Electrical insulating oil test method”.

  Further, the water content of the refrigerant refrigerant for hydrocarbon refrigerant of the present invention is not particularly limited, but it 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 the 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 refrigerant oil for hydrocarbon refrigerant of the present invention is not particularly limited, but it is contained in the refrigerator oil for hydrocarbon refrigerant of the present invention in order to prevent corrosion to the metal used in the refrigerator or piping. In order to prevent degradation of the ester oil, 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 JISK2501 "Petroleum products and lubricating oil-neutralization number test method".

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

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

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

  Examples of the HFC refrigerant include hydrofluorocarbons having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms. Specifically, for example, difluoromethane (HFC-32), trifluoromethane (HFC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1, HFC such as 1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), or two or more of these And the like.

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

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

  The refrigerating machine oil for hydrocarbon refrigerant of the present invention usually exists in the form of a working fluid composition for refrigerating machine mixed with a refrigerant containing hydrocarbon as described above in refrigerating and air-conditioning equipment. The mixing ratio of the refrigerating machine oil and the refrigerant in the working fluid composition for a refrigerating machine of the present invention 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. Part.

  The refrigerating machine oil for hydrocarbon refrigerant and the working fluid composition for refrigerating machine of the present invention have a reciprocating or rotating hermetic compressor, a room air conditioner, a packaged air conditioner, and a refrigerator because of their excellent electrical characteristics and low hygroscopicity. Is preferably used. The refrigeration oil for hydrocarbon refrigerant of the present invention is preferably used for cooling devices for automobile air conditioners, dehumidifiers, water heaters, freezers, refrigerated refrigerators, vending machines, showcases, chemical plants, and the like. Furthermore, the refrigerating machine oil for hydrocarbon refrigerant 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.

[Examples 1 to 4, Comparative Example 1]
In Examples 1 to 4 and Comparative Example 1, refrigerating machine oils were prepared using base oils 1 to 5 shown below. Various properties of the obtained refrigerating machine oil are shown in Table 1.
(Base oil)
Base oil 1: Ester base oil of oleic acid and neopentyl glycol 2: Ester base oil of oleic acid and trimethylolpropane 3: Ester base oil of oleic acid and pentaerythritol 4: 75 mol% of oleic acid and linoleic acid Ester base oil of 25 mol% mixed fatty acid and glycerin 5: 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid mixed fatty acid (mixing ratio: 2-ethylhexanoic acid / 3,5,5-trimethyl) Hexanoic acid = 50/50 (molar ratio)) and pentaerythritol ester

  Next, the following evaluation tests were carried out for each of the refrigerating machine oils of Examples 1 to 4 and Comparative Example 1.

(Lubricity)
Based on ASTM D 2670 “FALEX WEAR 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, while blowing 10 L / h of propane refrigerant, the tester was operated for 2 hours under a load of 250 lb, and the amount of wear of the test journal (pin) after the test was measured. The obtained results are shown in Table 1.

(Refrigerant compatibility)
Based on JIS-K-2211 “Refrigerating machine oil” “Compatibility testing method with refrigerant”, 2 g of refrigeration oil is blended with 18 g of propane refrigerant, and hydrocarbon refrigerant and refrigerating machine oil are mutually dissolved at 0 ° C. It was evaluated as “compatible”, “white turbidity”, and “separation”. The obtained results are shown in Table 1.

(Refrigerant melt viscosity)
The apparatus shown in FIG. 1 includes a pressure vessel 5 (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 propane refrigerant and refrigerating machine oil. It is possible. 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 propane refrigerant and refrigerating machine oil) is transferred from the thermocouple 3 to the temperature control means. A temperature-related data signal is sent, and a control signal is sent from the temperature control means to the thermostatic chamber 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 propane refrigerant was introduced, and the mixture of the propane refrigerant and the refrigerating machine oil was stirred with the stirrer 4 and the refrigerant. The pressure was adjusted to 0.7 MPa at 40 ° C. After stabilization, the viscosity of the mixture of propane refrigerant and refrigeration oil was measured. Table 1 shows the measurement results of the obtained 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 (2)

  A refrigerating machine oil for hydrocarbon refrigerant, characterized by containing an ester of a fatty acid and a polyhydric alcohol in which the proportion of linear fatty acids having 10 to 22 carbon atoms is 50 to 100 mol%. An ester of a fatty acid and a polyhydric alcohol in which the proportion of the linear fatty acid having 10 to 22 carbon atoms is 50 to 100 mol%;
A working fluid composition for a refrigerator, comprising a hydrocarbon refrigerant.

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