JP7198589B2 - Refrigerator, use of refrigerating machine oil, method for suppressing oligomer elution, refrigerating machine oil, working fluid composition for refrigerating machine, and method for producing refrigerating machine oil - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refrigerator, use of a refrigerator oil, a method for suppressing the elution of oligomers, a refrigerator oil, a working fluid composition for a refrigerator, and a method for producing a refrigerator oil.

Freezers such as refrigerators and air conditioners have a refrigerant circulation system that includes a compressor, a condenser, an expansion mechanism (expansion valve, capillary), an evaporator, etc. The refrigerant circulates in this refrigerant circulation system to cool it. is done.

On the other hand, the compressor in the refrigerant circulation system is filled with refrigerating machine oil to lubricate the sliding members. A part of this refrigerating machine oil dissolves in the refrigerant and circulates together with the refrigerant in the refrigerant circulation system. Refrigerating machine oil is used after optimizing each physical property such as viscosity according to desired properties such as lubricity and compatibility with a refrigerant. For example, in Patent Document 1, as a refrigerating machine oil having a low viscosity and excellent safety and stability, a refrigerating machine oil containing a predetermined monoester as a main component and having a kinematic viscosity at 40° C. of less than 7 mm ² /s is disclosed. disclosed.

JP 2009-235179 A

However, according to the study of the present inventors, in a refrigerant circulation system, if a refrigerating machine oil containing a low-viscosity base oil is used together with a fluorocarbon refrigerant, it is possible to use an organic polymer material such as polyethylene terephthalate or polybutylene terephthalate. It has been found that oligomers may be eluted from the member that has been treated. These oligomers may adhere to the suction valve and discharge valve of the compressor, causing problems such as poor opening and closing of the valve and clogging of the capillary of the expansion mechanism.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and its main object is to suppress the elution of oligomers from a member formed of an organic polymer material in a refrigerant circulation system.

In one aspect, the present invention includes a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and the refrigerant circulation system is filled with a fluorocarbon refrigerant and refrigerating machine oil. A refrigerator, wherein the refrigerant circulation system has a member made of an organic polymer material, the refrigerator oil is a fatty acid ester as a base oil, and the kinematic viscosity at 40° C. is 8 mm ² /s or less. and a fatty acid ester having a nonpolarity index of 50 or less; and a glycidyl-based acid scavenger.

Another aspect of the present invention is the use of refrigerating machine oil in a refrigerant circulation system provided in a refrigerator and filled with a fluorocarbon refrigerant, wherein the refrigerant circulation system is made of an organic polymer material. a fatty acid ester having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a nonpolarity index of 50 or less as a refrigerating machine oil and a fatty acid ester as a base oil; It is a use using a refrigerating machine oil containing an agent.

In another aspect of the present invention, a refrigerant circulation system provided in a refrigerator and filled with a fluorocarbon refrigerant, the refrigerant circulation system having a member made of an organic polymer material, wherein the base oil and a fatty acid ester having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less, and a glycidyl-based acid scavenger. is a method for suppressing elution of oligomers from members.

In another aspect of the present invention, a fatty acid ester as a base oil having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less, and a glycidyl-based acid A refrigerating machine oil containing a scavenger and used with a fluorocarbon refrigerant.

In each of the above aspects, the refrigerating machine oil preferably further contains a phosphorus-based extreme pressure agent. In this case, it is also excellent in that a decrease in the strength of the member formed of the organic polymer material can be suppressed. The glycidyl acid scavenger is preferably at least one selected from the group consisting of glycidyl ester compounds. In this case, it is also excellent in that a decrease in the strength of the member formed of the organic polymer material can be suppressed. Fatty acid esters may be diol esters.

In another aspect of the present invention, there is provided a working fluid composition for a refrigerator containing the above-described refrigerator oil and a fluorocarbon refrigerant.

In one aspect, the present invention selects a fatty acid ester as a base oil, which has a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less, and glycidyl-based acid A method for producing a refrigerating machine oil for a fluorocarbon refrigerant, comprising a step of mixing with a scavenger.

According to the present invention, it is possible to suppress the elution of oligomers from a member made of an organic polymer material in a refrigerant circulation system.

It is a mimetic diagram showing one embodiment of a refrigerator.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a schematic diagram showing one embodiment of a refrigerator. As shown in FIG. 1, a refrigerator 10 includes a compressor (refrigerant compressor) 1, a condenser (gas cooler) 2, an expansion mechanism 3 (capillary, expansion valve, etc.), and an evaporator (heat exchanger). 4 are sequentially connected by a flow path 5, at least a refrigerant circulation system 6 is provided.

In the refrigerant circulation system 6, first, the high-temperature (usually 70 to 120° C.) refrigerant discharged from the compressor 1 into the flow path 5 becomes a high-density fluid (such as a supercritical fluid) in the condenser 2. . Subsequently, the refrigerant is liquefied by passing through the narrow passage of the expansion mechanism 3, and further vaporized in the evaporator 4 to a low temperature (usually -40 to 0°C). Cooling by the refrigerator 10 utilizes a phenomenon in which the refrigerant takes heat from the surroundings when vaporized in the evaporator 4 .

In the compressor 1, a small amount of refrigerant and a large amount of refrigerating machine oil coexist under high temperature (normally 70 to 120° C.) conditions. The refrigerant discharged from the compressor 1 to the flow path 5 is gaseous and contains a small amount (usually 1 to 10% by volume) of refrigerating machine oil as a mist. The refrigerant is dissolved (point a in FIG. 1).

In the condenser 2, the gaseous refrigerant is compressed into a high-density fluid, and a large amount of refrigerant and a small amount of refrigerating machine oil coexist under relatively high temperature (usually 50 to 70 ° C.) conditions (Fig. 1 middle point b). Furthermore, a mixture of a large amount of refrigerant and a small amount of refrigerating machine oil is sequentially sent to the expansion mechanism 3 and the evaporator 4 and rapidly becomes low temperature (usually -40 to 0 ° C.) (points c and d in FIG. 1). It is returned to the compressor 1 again.

Examples of such a refrigerator 10 include automotive air conditioners, dehumidifiers, refrigerators, cold storage warehouses, vending machines, showcases, cooling devices in chemical plants, residential air conditioners, package air conditioners, hot water supply heat pumps, and the like. mentioned.

The refrigerant circulation system 6 has members made of an organic polymer material. More specifically, the member made of an organic polymer material is used, for example, as a sealing material for preventing leakage of refrigerant and refrigerating machine oil composition in an insulating portion in the compressor 1 or in the compressor 1. . The organic polymer material may be, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyamide, etc., preferably polyethylene terephthalate.

The refrigerant circulation system 6 described above is filled with a fluorocarbon refrigerant and refrigerating machine oil.

Examples of fluorocarbon refrigerants include saturated fluorohydrocarbon refrigerants, unsaturated fluorohydrocarbon refrigerants, and mixed refrigerants thereof. Specific examples of saturated fluorocarbon refrigerants include difluoromethane (R32 (also called HFC-32; hereinafter the same)), trifluoromethane (R23), pentafluoroethane (R125), 1,1, 2,2-tetrafluoroethane (R134), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1-difluoroethane (R152a), fluoroethane (R161), 1,1,1,2,3,3,3-heptafluoropropane (R227ea), 1,1,1,2,3,3-hexafluoropropane (R236ea), 1,1,1, 3,3,3-hexafluoropropane (R236fa), 1,1,1,3,3-pentafluoropropane (R245fa), and 1,1,1,3,3-pentafluorobutane (R365mfc), or these and mixtures of two or more of Further, specific examples of unsaturated fluorohydrocarbon refrigerants include fluoropropene refrigerants such as 2,3,3,3-tetrafluoropropene and 1,3,3,3-tetrafluoropropene. be done.

R134a alone; R125 alone; a mixture of R134a/R32 = 60-80% by mass/40-20% by mass; R32/R125 = 40-70% by mass/60 ~30 wt% mixture; R125/R143a = 40-60 wt%/60-40 wt% mixture; R134a/R32/R125 = 60 wt%/30 wt%/10 wt% mixture; R134a/R32/R125 = 40-70 mass%/15-35 mass%/5-40 mass% mixture; R125/R134a/R143a=35-55 mass%/1-15 mass%/40-60 mass% mixture, etc. Well, more specifically, a mixture of R134a/R32 = 70/30% by weight; a mixture of R32/R125 = 60/40% by weight; a mixture of R32/R125 = 50/50% by weight (R410A); = 45/55% by weight mixture (R410B); R125/R143a = 50/50% by weight mixture (R507C); R32/R125/R134a = 30/10/60% by weight mixture; R32/R125/R134a = 23 /25/52 mass% mixture (R407C); R32/R125/R134a = 25/15/60 mass% mixture (R407E); R125/R134a/R143a = 44/4/52 mass% mixture (R404A), etc. can be

The saturated fluorohydrocarbon refrigerant preferably contains 1,1,1,2-tetrafluoroethane (R134a (HFC-134a)), more preferably substantially 1,1,1,2-tetrafluoroethane It consists only of (R134a (HFC-134a)).

The refrigerant filled in the refrigerant circulation system 6 may further contain other refrigerants in addition to the fluorocarbon refrigerant. Other refrigerants include fluorine-containing ether refrigerants such as perfluoroethers, bis(trifluoromethyl)sulfide refrigerants, trifluoroiodide methane refrigerants, natural refrigerants such as dimethyl ether, carbon dioxide, ammonia and hydrocarbons. exemplified.

The refrigerator oil contains a fatty acid ester as a base oil and a glycidyl-based acid scavenger.

Fatty acid esters are esters of alcohols and fatty acids, may be monoesters of monohydric alcohols and fatty acids, and may be polyol esters of polyhydric alcohols and fatty acids. The monoester is an ester of a fatty acid having 1 to 20 carbon atoms, preferably a fatty acid having 3 to 10 carbon atoms, and a monohydric alcohol having 1 to 20 carbon atoms, preferably a monohydric alcohol having 3 to 10 carbon atoms. good. Fatty acid esters are preferably polyol esters.

The polyol ester may be a partial ester in which some of the hydroxyl groups of the polyhydric alcohol are not esterified and remain as hydroxyl groups, or may be a complete ester in which all the hydroxyl groups are esterified, or may be a partial ester. and complete esters. The hydroxyl value of the fatty acid ester (preferably polyol ester) is preferably 10 mgKOH/g or less, more preferably 5 mgKOH/g or less, more preferably 3 mgKOH/g or less. A hydroxyl value in the present invention means a hydroxyl value measured according to JIS K0070:1992.

The polyhydric alcohol constituting the polyol ester may be a polyhydric alcohol having 2 to 6 hydroxyl groups, or may be a polyhydric alcohol (diol) having two hydroxyl groups. Examples of polyhydric alcohols (diols) having two hydroxyl groups 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, 12-dodecanediol and the like. Examples of polyhydric alcohols having 3 or more hydroxyl groups include trimethylolethane, trimethylolpropane, trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, dipentaerythritol, tri-( pentaerythritol), glycerin, polyglycerin (dimer to trimer of glycerin), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensate, polyhydric alcohol such as adonitol, arabitol, xylitol, mannitol, xylose , arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, and partially etherified products thereof. The polyhydric alcohol is preferably at least one selected from the group consisting of neopentyl glycol, trimethylolpropane and pentaerythritol.

Fatty acids constituting fatty acid esters (preferably polyol esters) are preferably saturated fatty acids. The number of carbon atoms in the fatty acid is preferably 4-20, more preferably 4-18, even more preferably 4-9, and particularly preferably 5-9. Fatty acids having 4 to 20 carbon atoms include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, and heptadecane. acid, octadecanoic acid, nonadecanic acid, icosanoic acid, and the like. These fatty acids having 4 to 20 carbon atoms may be linear or branched, preferably branched. The branched fatty acid having 4 to 20 carbon atoms is preferably a fatty acid having a branch at least one selected from the group consisting of α-position and β-position, more preferably 2-methylpropanoic acid, 2-methylbutanoic acid, 2 -methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, or 2-ethylhexadecanoic acid, more preferably is 2-ethylhexanoic acid or 3,5,5-trimethylhexanoic acid.

The fatty acid ester (preferably polyol ester) may be a diol ester of a diol and a fatty acid, or may be a diol ester of a diol and a fatty acid having 4 to 20 carbon atoms. -diol ester of ethylhexanoic acid, diol ester of neopentyl glycol and 3,5,5-trimethylhexanoic acid, and the like.

The kinematic viscosity of the fatty acid ester (preferably polyol ester) at 40° C. may be 2 mm ² /s or more, 3 mm ² /s or more, or 4 mm ² /s or more, and 8 mm ² /s or less, or 7.6 mm ² /s. may be: The kinematic viscosity of the fatty acid ester (preferably polyol ester) at 100° C. may be 0.5 mm ² /s or more, 1 mm ² /s or more, or 1.5 mm ² /s or more, and 5 mm ² /s or less, 4 mm ² /s or less or 3 mm ² /s or less. Kinematic viscosity in the present invention means kinematic viscosity measured according to JIS K-2283:1993.

The non-polarity index of the fatty acid ester (preferably polyol ester) may be 20 or more, 30 or more or 35 or more and may be 50 or less, 45 or less or 40 or less. The non-polarity index of the monoester may be 20 or greater, 30 or greater, 35 or greater or 40 or greater, and may be 50 or less or 45 or less. The non-polarity index of fatty acid ester is calculated according to the following formula (1).
Non-polarity index = (number of carbon atoms x molecular weight)/(number of ester groups x 100) (1)
In formula (1), the number of carbon atoms represents the number of carbon atoms constituting the fatty acid ester, the molecular weight represents the molecular weight of the fatty acid ester, and the number of ester groups represents the number of ester groups in one molecule of the fatty acid ester.

The content of fatty acid ester (preferably polyol ester) may be 50% by mass or more, 60% by mass or more, or 65% by mass or more based on the total amount of refrigerating machine oil. When the fatty acid ester contains a polyol ester and a monoester, the content of the monoester is preferably 50% by mass or less, more preferably 40% by mass or less or 35% by mass or less, based on the total amount of refrigerating machine oil.

The base oil may further contain other base oils in addition to the above fatty acid esters (preferably polyol esters). Other base oils include, for example, mineral oils, olefin polymers, naphthalene compounds, hydrocarbon oils such as alkylbenzene, esters other than the above fatty acid esters, polyalkylene glycols, polyvinyl ethers, ketones, polyphenyl ethers, silicones, Synthetic oils (oxygen-containing oils) containing oxygen as a constituent element such as polysiloxane and perfluoroether can be mentioned. Among the above oxygen-containing oils, esters, polyalkylene glycols, polyvinyl ethers, and ketones are preferably used.

Other esters may be esters other than the above fatty acid esters. The nonpolarity index of other esters is, for example, 40 or more and may be 100 or less, preferably 40 or more and 70 or less, more preferably 40 or more and 50 or less.

The content of other base oils may be 50% by mass or less, preferably 40% by mass or less or 35% by mass or less, based on the total amount of refrigerating machine oil.

The non-polarity index of the base oil is 30 to 50, preferably 35, since the combined use of a glycidyl-based acid scavenger and a phosphorus-based extreme pressure agent, which will be described later, can further suppress the elution of oligomers from high-molecular-weight organic materials. ~45. Thus, in this embodiment, it is possible to produce a refrigerating machine oil with a lower viscosity.

The kinematic viscosity of the base oil at 40° C. is preferably 1 mm ² /s or more, more preferably 2 mm ² /s or more, still more preferably 3 mm ² /s or more, and preferably 8 mm ² /s or less, More preferably, it may be 6 mm ² /s or less, and still more preferably 5.5 mm ² /s or less. The kinematic viscosity of the base oil at 100° C. is preferably 0.5 mm ² /s or more, more preferably 1 mm ² /s or more, still more preferably 1.2 mm ² /s or more, and preferably 4 mm ² /s or less, more preferably 3 mm ² /s or less, and even more preferably 2 mm ² /s or less.

The content of the base oil is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more, based on the total amount of the refrigerating machine oil.

The refrigerator oil contains a glycidyl-based acid scavenger in addition to the base oil. The glycidyl-based acid scavenger contains at least one compound having a glycidyl group. The glycidyl-based acid scavenger may be, for example, a glycidyl ester compound or a glycidyl ether compound, and is preferably a glycidyl ester compound from the viewpoint of suppressing a decrease in strength of a member formed of an organic polymer material. These glycidyl-based acid scavengers can be used singly or in combination of two or more.

式（２）中、Ｒ^１はアリール基、炭素数５～１８のアルキル基、又はアルケニル基を示す。 Examples of glycidyl ester compounds include compounds represented by the following formula (2).

In formula (2), R ¹ represents an aryl group, an alkyl group having 5 to 18 carbon atoms, or an alkenyl group.

The glycidyl ester compound represented by formula (2) is preferably glycidyl benzoate, glycidyl neodecanoate, glycidyl-2,2-dimethyloctanoate, glycidyl acrylate and glycidyl methacrylate.

When the number of carbon atoms in the alkyl group represented by R ¹ is 5 or more, the stability of the glycidyl ester compound is ensured, and the glycidyl ester compound is decomposed before reacting with moisture, fatty acids, and oxidation degradation products, and the glycidyl ester compounds are polymerized with each other. It is possible to suppress the occurrence of self-polymerization, which makes it easier to obtain the desired function. On the other hand, when the number of carbon atoms in the alkyl group or alkenyl group represented by R ¹ is 18 or less, the solubility in the refrigerant is kept good, and it is difficult to cause problems such as poor cooling due to precipitation in the refrigerator. can.

式（３）中、Ｒ^２はアリール基又は炭素数５～１８のアルキル基を示す。 Examples of glycidyl ether compounds include aryl glycidyl ether compounds and alkyl glycidyl ether compounds represented by the following formula (3).

In formula (3), R ² represents an aryl group or an alkyl group having 5 to 18 carbon atoms.

The glycidyl ether compound represented by formula (3) is preferably 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 glycidyl ether, decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, 2-ethylhexyl glycidyl is ether.

When the number of carbon atoms in the alkyl group represented by R ² is 5 or more, the stability of the glycidyl ether compound is ensured, and the glycidyl ether compound is decomposed before reacting with moisture, fatty acids, and oxidation degradation products, and the glycidyl ether compounds are polymerized with each other. It is possible to suppress the occurrence of self-polymerization, which makes it easier to obtain the desired function. On the other hand, when the number of carbon atoms in the alkyl group represented by R ² is 18 or less, good solubility in the refrigerant is maintained, and problems such as poor cooling caused by precipitation in the refrigeration system can be prevented.

Glycidyl ether compounds include neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1,6-hexanediol diglycidyl ether, sorbitol polyglycidyl ether, in addition to compounds represented by formula (3). Ethers, polyalkylene glycol monoglycidyl ethers, polyalkylene glycol diglycidyl ethers, and the like may also be used.

From the viewpoint of further suppressing the elution of oligomers, the content of the glycidyl-based acid scavenger is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably 0.2% by mass, based on the total amount of refrigerating machine oil. It is 3 mass % or more. The content of the glycidyl-based acid scavenger is preferably 5% by mass or less based on the total amount of refrigerating machine oil, from the viewpoint of further suppressing the elution of oligomers and further suppressing the decrease in strength of members formed of organic polymer materials. , more preferably 3% by mass or less, and still more preferably 1% by mass or less. When the refrigerating machine oil does not contain a phosphorus-based additive, the content of a glycidyl-based acid scavenger, such as a glycidyl ester compound, is set to 0.2 to 0.4% by mass, so that it is formed of an organic polymer material. It is possible to further suppress a decrease in the strength of the member that has been treated. From this point of view, a glycidyl ester-based acid scavenger is more preferable than a glycidyl ether-based acid scavenger.

The refrigerator oil preferably further contains a phosphorus-based extreme pressure agent. When the refrigerating machine oil contains a glycidyl ether compound as a glycidyl-based acid scavenger, further containing a phosphorus-based extreme pressure agent in the refrigerating machine oil can suppress a decrease in strength of a member formed of an organic polymer material. When the refrigerating machine oil contains a glycidyl ester compound as a glycidyl-based acid scavenger, further containing a phosphorus-based extreme pressure agent in the refrigerating machine oil further suppresses the elution of oligomers, thereby improving the performance of members made of organic polymer materials. A decrease in strength can be suppressed.

Phosphorus-based extreme pressure agents include, but are not limited to, phosphates, acidic phosphates, thiophosphates, amine salts of acidic phosphates, chlorinated phosphates, and phosphites. These phosphorus compounds can be used individually by 1 type or in combination of 2 or more types.

Phosphate esters include 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, xylenyl diphenyl phosphate, etc. mentioned.

式（４）中、Ｒ^３は、炭素数１～４のアルキル基、すなわち、メチル基、エチル基、直鎖若しくは分岐のプロピル基、又は、直鎖若しくは分岐のブチル基（その置換位置は任意である）を表し、ｍは０～３の整数を表す。 The phosphate ester is preferably a phosphate ester represented by the following formula (4). This phosphoric acid ester is triphenyl phosphate or triaryl phosphate in which an alkyl group having 1 to 4 carbon atoms is added to the phenyl group of triphenyl phosphate.

In formula (4), R ³ is an alkyl group having 1 to 4 carbon atoms, that is, a methyl group, an ethyl group, a linear or branched propyl group, or a linear or branched butyl group (the substitution position of which is arbitrary). ), and m represents an integer of 0 to 3.

Acidic phosphates 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, Nooleyl Acid Phosphate, Dibutyl Acid Phosphate, Dipentyl Acid Phosphate , dihexyl acid phosphate, 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 phosphate , dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, dioleyl acid phosphate and the like.

Thiophosphates include tributyl phosphorothionate, tripentyl phosphorothionate, trihexyl phosphorothionate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl phosphorothionate, tridecylphosphothionate follothionate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl phosphorothionate, trihexadecyl phosphorothionate, triheptadecyl phosphorothionate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, tricresyl phosphorothionate, trixylenyl phosphorothionate, cresyl diphenyl phosphorothionate thionates, xylenyldiphenylphosphorothionates, and the like.

Amine salts of acidic phosphates include the above acidic phosphates and methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, di Salts with amines such as butylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, and trioctylamine. .

Chlorinated phosphate esters include tris-dichloropropyl phosphate, tris-chloroethyl phosphate, tris-chlorophenyl phosphate, polyoxyalkylene bis[di(chloroalkyl)]phosphate and the like. Phosphites include dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl Phosphite, diphenylphosphite, dicresylphosphite, tributylphosphite, tripentylphosphite, trihexylphosphite, triheptylphosphite, trioctylphosphite, trinonylphosphite, tridecylphosphite, triundecylphosphite phyto, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, tricresyl phosphite and the like.

The content of the phosphorus-based extreme pressure agent is preferably 0.1 mass based on the total amount of refrigerating machine oil from the viewpoint of further suppressing the elution of oligomers and further suppressing the decrease in strength of members formed of organic polymer materials. % or more, more preferably 0.4 mass % or more, and still more preferably 0.8 mass % or more. The content of the phosphorus-based extreme pressure agent is preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 1.5% by mass, based on the total amount of refrigerating machine oil, from the viewpoint of suitably obtaining an effect commensurate with the content. % or less. When the refrigerating machine oil contains a phosphorus-based extreme pressure agent, the use of a glycidyl ester compound as the glycidyl-based acid scavenger makes it easier to suppress the elution of oligomers from members made of organic polymer materials. It becomes easier to suppress the decrease in strength. That is, the refrigerator oil preferably contains a glycidyl ester compound and a phosphorus-based extreme pressure agent.

The refrigerator oil preferably further contains an antioxidant. Antioxidants are, for example, 2,6-di-tert. -Phenolic antioxidants such as butyl-p-cresol and bisphenol A, or amine antioxidants such as phenyl-α-naphthylamine and N,N-di(2-naphthyl)-p-phenylenediamine. preferably 2,6-di-tert. -butyl-p-cresol. From the viewpoint of excellent stability of the refrigerating machine oil, the content of the antioxidant is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, and still more preferably 0.08% by mass, based on the total amount of the refrigerating machine oil. % or more. From the viewpoint of suppressing coloring of the refrigerating machine oil due to the antioxidant, the content of the antioxidant is preferably 0.4% by mass or less, more preferably 0.3% by mass or less, and still more preferably 0.3% by mass or less, based on the total amount of the refrigerating machine oil. It is 0.2% by mass or less.

The refrigerating machine oil may further contain conventionally known additives for refrigerating machine oil, if necessary, in order to further enhance its performance. Such additives include acid scavengers other than glycidyl-based acid scavengers, extreme pressure agents other than phosphorus-based extreme pressure agents, oiliness agents, antifoaming agents, metal deactivators, antiwear agents, viscosity index improvers, Pour point depressants, detergent dispersants and the like. These additives are used singly or in combination of two or more. The content of these additives is not particularly limited, but may be 10% by mass or less or 5% by mass or less based on the total amount of refrigerating machine oil.

The kinematic viscosity of the refrigerator oil at 40° C. is preferably 1 mm ² /s or more, more preferably 2 mm ² /s or more, still more preferably 3 mm ² /s or more, and preferably 8 mm ² /s or less, More preferably, it may be 6 mm ² /s or less, and still more preferably 5.5 mm ² /s or less. The kinematic viscosity of the refrigerator oil at 100° C. is preferably 0.5 m ² /s or more, more preferably 1 mm ² /s or more, still more preferably 1.5 mm ² /s or more, and preferably 4 mm ² /s or less, more preferably 3 mm ² /s or less, and even more preferably 2 mm ² /s or less.

The volume resistivity of the refrigerator oil is preferably 1.0×10 ¹² Ω·cm or more, more preferably 1.0×10 ¹³ Ω·cm or more, and still more preferably 1.0×10 ¹⁴ Ω·cm or more. you can In particular, when used in a closed-type refrigerator, high electrical insulation tends to be required. The volume resistivity in the present invention means the volume resistivity at 25° C. measured according to JIS C2101:1999 "Electrical insulating oil test method".

The moisture content of the refrigerator oil may be preferably 200 ppm or less, more preferably 100 ppm or less, still more preferably 50 ppm or less, based on the total amount of the refrigerator oil. In particular, when used in a closed-type refrigerator, the water content is required to be small from the viewpoint of the influence on the thermal/chemical stability and electrical insulation of the refrigerator oil.

The acid value of the refrigerator oil may be preferably 0.1 mgKOH/g or less, more preferably 0.05 mgKOH/g or less. The hydroxyl value of the refrigerator oil may be preferably 5.0 mgKOH/g or less, more preferably 2.0 mgKOH/g or less. When the acid value and hydroxyl value of the refrigerating machine oil satisfy the above conditions, it is possible to prevent corrosion of metals used in the refrigerating machine or piping. The acid value in the present invention means an acid value measured according to JIS K2501:2003 "Petroleum products and lubricating oils-neutralization value test method".

The ash content of the refrigerator oil is preferably 100 ppm or less, more preferably 50 ppm or less, in order to improve the thermal and chemical stability of the refrigerator oil and suppress the generation of sludge and the like. The ash content in the present invention means the ash content measured according to JIS K2272:1998 "Determination of ash content and sulfated ash content of crude oil and petroleum products".

The pour point of the refrigerator oil is preferably -10°C or lower, more preferably -20°C or lower, and even more preferably -30°C or lower. The pour point in the present invention means the pour point measured according to JIS K2269:1987.

The refrigerator oil according to this embodiment is used together with a fluorocarbon refrigerant. A working fluid composition for a refrigerator according to the present embodiment contains the above-described refrigerator oil and a fluorocarbon refrigerant. The fluorinated hydrocarbon refrigerant and other refrigerants in each of these embodiments are the same as described above.

The content of refrigerating machine oil in the working fluid composition for a refrigerating machine may be preferably 1 to 500 parts by mass, more preferably 2 to 400 parts by mass with respect to 100 parts by mass of refrigerant.

The refrigerating machine oil is produced, for example, by a production method comprising a step of selecting the fatty acid ester as a base oil and mixing the fatty acid ester with a glycidyl-based acid scavenger.

The refrigerating machine oil and the working fluid composition for a refrigerating machine according to the present embodiment are preferably used in the refrigerant circulation system 6 having members formed of the above-described organic polymer materials, and the members formed of the organic polymer materials are elution of the oligomer can be suppressed.

EXAMPLES The present invention will be described in more detail based on examples below, but the present invention is not limited to the examples.

Ｄ１：２，６－ジ－ｔｅｒｔ．－ブチル－ｐ－クレゾール In Examples, Comparative Examples and Reference Examples, refrigerating machine oils having compositions shown in Tables 1 to 3 were prepared using the base oils and additives shown below. In the table, the composition of the refrigerating machine oil is represented by mass% based on the total amount of the refrigerating machine oil.
(base oil)
A1: Diester of 2-ethylhexanoic acid and neopentyl glycol (kinematic viscosity at 40° C.: 7.3 mm ² /s, kinematic viscosity at 100° C.: 2.0 mm ² /s, nonpolar index 36.3, A1/ Low temperature two-layer separation temperature of R134a = 1/9 (mass ratio: -32 ° C.)
A2: Monoester of 2-ethylhexanoic acid and 2-ethylhexanol (kinematic viscosity at 40° C.: 2.7 mm ² /s, kinematic viscosity at 100° C.: 1.1 mm ² /s, nonpolar index 41, A2/ Low temperature two-layer separation temperature of R134a = 1/9 (mass ratio): <-60 ° C))
A3: A1/A2 = 7/3 (mass ratio) (kinematic viscosity at 40°C: 5.2 mm ² /s, kinematic viscosity at 100°C: 1.6 mm ² /s, nonpolar index 37.7, A4/R134a = 1/9 (mass ratio) low-temperature two-layer separation temperature: <-60 ° C)
A4: Tetraester of 2-ethylhexanoic acid and pentaerythritol (kinematic viscosity at 40° C.: 45.3 mm ² /s, kinematic viscosity at 100° C.: 6.3 mm ² /s, nonpolar index 59.2, A3/ Low-temperature two-layer separation temperature of R134a = 1/9 (mass ratio): -21 ° C))
(Additive)
B1: glycidyl dimethyl octanoate B2: 2-ethylhexyl glycidyl ether C1: tricresyl phosphate C2: butylated triphenyl phosphate (a mixture of compounds in which m in the following formula (4a) is 0, 1, 2 and 3)

D1: 2,6-di-tert. -butyl-p-cresol

(Measurement of elution amount of oligomer)
80 g of refrigerating machine oil and polyethylene terephthalate films (three dumbbell-shaped pieces) are placed in a 200 mL autoclave test container (glass container), sealed, and after vacuuming at a low temperature, 1, 1, 1, 20 g of 2-tetrafluoroethane refrigerant was charged and left at 175° C. for one week. Thereafter, the recovered refrigerator oil was filtered through a 0.8 μm filter, washed with n-hexane, and dried. The difference in weight of the filter before and after filtration was defined as the elution amount of the oligomer. The results obtained are shown in Tables 1-3.

When the refrigerating machine oils containing the glycidyl-based acid scavengers of Examples 1 to 9 are used, the effect of suppressing the oligomer elution is compared to the case of using the refrigerating machine oils not containing the glycidyl-based acid scavengers of Comparative Examples 1-3. was found to be large. When the refrigerating machine oil of Reference Example 1 was used, the amount of oligomer eluted was originally small, and even if a glycidyl-based acid scavenger was further added, the effect of suppressing the amount of oligomer eluted was small.

For Examples 3 to 9, the tensile strength of the polyethylene terephthalate resin subjected to the above "measurement of oligomer elution amount" was measured according to JIS K6251:2010. Table 4 shows the results obtained.

When additive B1 was added, it was highly effective in suppressing the amount of oligomer elution and improving tensile strength, and the effect of combined use with the phosphorus-based additive was also recognized. The addition of additive B2 was also effective in suppressing the amount of eluted oligomers, and when used in combination with the phosphorus-based additive, although the amount of eluted oligomers slightly increased, a joint effect was observed in terms of tensile strength.

DESCRIPTION OF SYMBOLS 1... Compressor, 2... Condenser, 3... Expansion mechanism, 4... Evaporator, 5... Flow path, 6... Refrigerant circulation system, 10... Refrigerator.

Claims (12)

A refrigerator comprising a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, wherein the refrigerant circulation system is filled with a fluorocarbon refrigerant and a refrigerator oil,
The refrigerant circulation system has a member made of at least one organic polymer material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate,
The refrigerating machine oil is
a monoester of a monohydric alcohol as a base oil and a fatty acid, the monoester having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less;
and a glycidyl-based acid scavenger. 2. The refrigerator according to claim 1, wherein said refrigerator oil further contains a phosphorus-based extreme pressure agent. 3. The refrigerator according to claim 1, wherein said glycidyl-based acid scavenger is at least one selected from the group consisting of glycidyl ester compounds. The refrigerator according to any one of claims 1 to 3 , wherein the base oil has a kinematic viscosity at 40°C of 6 mm ² /s or less. Use of refrigerating machine oil in a refrigerant circulation system provided in a refrigerating machine and filled with a fluorocarbon refrigerant,
The refrigerant circulation system has a member made of at least one organic polymer material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate,
As the refrigerating machine oil,
a monoester of a monohydric alcohol as a base oil and a fatty acid, the monoester having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less;
A use using a refrigerating machine oil containing a glycidyl-based acid scavenger. A refrigerant circulation system provided in a refrigerator and filled with a fluorinated hydrocarbon refrigerant, and made of at least one organic polymer material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. In a refrigerant circulation system having a member,
a monoester of a monohydric alcohol as a base oil and a fatty acid, the monoester having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less;
A method for suppressing elution of oligomers from the member by using a refrigerating machine oil containing a glycidyl-based acid scavenger. a monoester of a monohydric alcohol as a base oil and a fatty acid, the monoester having a kinematic viscosity at 40° C. of 8 mm ² /s or less and a non-polarity index of 50 or less;
a glycidyl-based acid scavenger;
contains
A refrigerant circulation system filled with a fluorocarbon refrigerant and having a member made of at least one organic polymer material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, refrigerator oil. 8. The refrigerating machine oil according to claim 7 , further comprising a phosphorus-based extreme pressure agent. The refrigerating machine oil according to claim 7 or 8 , wherein said glycidyl-based acid scavenger is at least one selected from the group consisting of glycidyl ester compounds. The refrigerating machine oil according to any one of claims 7 to 9 , wherein the base oil has a kinematic viscosity at 40°C of 6 mm ² /s or less. The refrigerating machine oil according to any one of claims 7 to 10 ,
and a fluorocarbon refrigerant. A monoester of a monohydric alcohol as a base oil and a fatty acid having a kinematic viscosity of 8 mm ² /s or less at 40° C. and a non-polarity index of 50 or less is selected, and a glycidyl-based acid-scavenging monoester is selected. A method for producing refrigerating machine oil comprising a step of mixing with an agent,
The refrigerating machine oil is filled with a fluorinated hydrocarbon refrigerant and has a member made of at least one organic polymer material selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate for refrigerant circulation. A method for producing refrigerating machine oil used in the system.

Images