KR20070087513A - Refrigerator oil for hydrocarbon refrigerant and refrigerator system using the same - Google Patents

Abstract

assignment

When refrigeration oil mainly containing lower hydrocarbon refrigerant and mineral oil is used, oligomers generated in the working fluid are suppressed.

Resolution

A refrigerant oil containing a refrigerant having 1 to 5 carbon atoms and a refrigerant fluid containing a refrigeration oil is used in a refrigeration system in contact with an organic polymer material in the refrigeration system. It contains 1-15 weight% of synthetic oils which consist of organic compounds containing two or more oxygen atoms. The organic compound containing an oxygen atom having an ester bond and / or an ether bond, the organic compound containing an oxygen atom being a polyol ester of neopentylpolyol and a monovalent fatty acid having 4 to 12 carbon atoms, the refrigerant being propane and // Or isobutane, and it is preferable that the organic polymer material is polyethylene terephthalate and / or polybutylene terephthalate.

Description

REFRIGERATING MACHINE OIL FOR HYDROCARBON REFRIGERANT AND REFRIGERATING MACHINE SYSTEM USING THE SAME}

Patent Document 1: Japanese Unexamined Patent Publication No. 2003-041278

Patent Document 2: Japanese Unexamined Patent Publication No. 2005-162883

Patent Document 3: International Publication No. WO2000 / 60031

Technical field

The present invention is not concerned with destroying the ozone layer, and also has a global warming capacity that is much lower than that of a halogen-containing hydrocarbon refrigerant, especially a lubricant for a refrigerator using propane or isobutane, and a refrigerator system using the same. It is about.

Background technology

Generally, a refrigerator system compresses a refrigerant with a compressor, heats the refrigerant which has become a high pressure and a high temperature with a condenser, and then lowers the pressure by an expansion mechanism (e.g., an expansion valve). In this case, when the refrigerant evaporates, the heat of evaporation is removed from the surroundings so that the cooling is performed at a low temperature. This refrigerator system is used for refrigerators, freezers, air conditioning, showcases, vending machines such as soft drinks and ice cream. In addition, in air-conditioning, vending machines, etc., it is used to heat using the heat which arises at the time of condensation, and to heat and maintain a drink or food.

Conventionally, as the refrigerant, fluorinated hydrocarbons (CFC or HCFC) containing chlorine such as trichlorofluoromethane (R11), dichlorodifluoromethane (R12), and chlorodifluoromethane (R22) have been used. However, since these CFCs and HCFCs cause environmental problems that destroy the ozone layer, their production and use are regulated internationally and currently do not contain chlorine, for example, difluoromethane (R32), tetrafluoro Non-chlorinated fluorinated hydrocarbons (HFCs), such as roethane (R134 or R134a) and difluoroethane (R152 or R152a), are being converted into so-called replacement flons.

However, although these replacement flons do not destroy the ozone layer, they are not preferable from the long-term viewpoint of global environmental protection due to their high global warming ability. On the other hand, low molecular weight hydrocarbons and ammonia having about 1 to 5 carbon atoms are not suitable for the ozone layer. Since it does not destroy and the global warming ability is also very low compared with the chlorine-based or non-chlorine-based fluorinated hydrocarbons, it is attracting attention as an environmentally friendly refrigerant (Patent Documents 1 and 2).

In a refrigerator system, the working fluid which mixed the refrigerant | coolant and what is called freezer oil is circulated in a system for lubrication in a compressor. The refrigeration oil used for such a working fluid requires compatibility with a refrigerant and lubrication performance. For example, the present inventor proposes to use a mineral oil having a specific property as a refrigeration oil suitable for a lower hydrocarbon refrigerant. (Patent Document 3).

By the way, when using the refrigeration oil which has a lower hydrocarbon refrigerant and mineral oil as a main component as a working fluid, it discovered that the oligomer (polymer material) which consists of organic substance generate | occur | produces in a working fluid. Such oligomers may clog the capillary of the expansion valve or adhere to the valve of the compressor, resulting in poor opening and closing.

The present invention has been made to solve the above problems, and an object of the present invention is to suppress an oligomer generated in a working fluid when a refrigeration oil mainly containing a lower hydrocarbon refrigerant and a mineral oil is used. MEANS TO SOLVE THE PROBLEM The present inventors discovered that oligomer can be suppressed by containing a predetermined amount of specific organic compounds in refrigerator oil, and came to complete this invention.

Means to solve the problem

The refrigeration oil for hydrocarbon refrigerant according to the present invention is a refrigeration oil used in a refrigeration system in which a refrigerant containing a hydrocarbon having 1 to 5 carbon atoms and a working fluid containing a refrigeration oil come into contact with an organic polymer material in the refrigeration system. It contains 85 to 99 weight% of mineral oil and 1 to 15 weight% of synthetic oil which consists of an organic compound containing 2 or more oxygen atoms in a molecule | numerator. The refrigerator system according to the present invention is a refrigerator system in which a working fluid containing a refrigerant containing a C1-C5 hydrocarbon and a refrigerant oil comes into contact with an organic polymer material inside the refrigerator system, wherein the refrigerator oil is a mineral oil 85 It is characterized by containing 1 to 15 weight% of synthetic oil which consists of -99 weight% and the organic compound containing two or more oxygen atoms in a molecule | numerator. In the refrigeration oil and refrigeration system for a hydrocarbon refrigerant of the present invention, the organic compound containing an oxygen atom has an ester bond and / or an ether bond, and the organic compound containing an oxygen atom is neopentyl polyol and 4 to 12 carbon atoms. It is preferable that the polyol ester of monovalent fatty acid, the refrigerant is propane and / or isobutane, or the organic polymer material is polyethylene terephthalate and / or polybutylene terephthalate.

To practice the invention  Best form for

[Frozen base oil]

The refrigeration oil of the present invention is 85 to 99% by weight of mineral oil, preferably 88 to 97% by weight, and 1 to 15% by weight of synthetic oil, preferably 3 to 3, consisting of an organic compound containing two or more oxygen atoms in the molecule. It contains 12 weight%. When the content of the synthetic oil composed of organic compounds containing two or more oxygen atoms in the molecule is less than 1% by weight or more than 15% by weight (that is, when the content of mineral oil is more than 99% by weight or less than 85% by weight), the oligomer Can not be sufficiently suppressed.

As for the refrigeration oil of this invention, it is preferable that dynamic viscosity in 40 degreeC is 3-150 mm <2> / s, especially 5-100 mm <2> / s, and it is more preferable that a pour point is -25 degrees C or less. If the pour point is higher than -25 ° C, the lubricant discharged from the compressor together with the refrigerant is deteriorated in fluidity by an expansion mechanism or an evaporator, and stays at a low temperature part of the refrigeration plant, resulting in a decrease in heat transfer efficiency or a lack of lubricant in the compressor. There is a fear that the bearing may be worn or pressed, which is not preferable. In addition, a pour point is usually -60 degreeC or more. Moreover, it is further more preferable that a viscosity index is 20 or more, especially 50 or more and 80 or more, and a viscosity index is 120 or less normally. In the refrigeration cycle, the lubricant is heated at the compressor discharge and exposed to low temperatures at the outlet of the expansion mechanism and used in a relatively wide temperature range. Accordingly, a lubricant having a high viscosity index with a small viscosity change due to temperature, that is, a mineral oil having a high viscosity index is desired. Generally, lubricants containing a lot of long chain hydrocarbons tend to have high viscosity indexes and high lubricating performance.

[Mineral oil]

As a mineral oil, it is preferable to use the mineral oil which has the properties of% CA or less, nitrogen content of 50 ppm or less, and sulfur content of 2,000 ppm or less by n-d-M ring analysis. The value of% CA greatly affects the viscosity index, and as this increases, the viscosity index is lowered, which is not very desirable as a refrigeration oil in the mineral oil having a% CA of more than 15. In addition, the mineral oil having a high CP of 40 or more, particularly 50 or more, has a high lubricity and can maintain sufficient lubricity even when diluted with a hydrocarbon refrigerant having low lubricity, and it becomes difficult to cause wear or sticking of the bearings. It is preferable to use mineral oil, and it is more preferable to use mineral oil of 50 or more of% CP. These% CA and% CP can be calculated | required by the n-d-M ring analysis prescribed | regulated by ASTMD3238.

Moreover, nitrogen content and sulfur content contained in mineral oil may adversely affect the characteristic of lubricating oil. When nitrogen content exceeds 50 ppm, there exists a tendency for the stability to worsen, and it is preferable to set it as 50 ppm or less. Moreover, since sulfur has corrosiveness, it is preferable to set it as 2,000 ppm or less. In addition, nitrogen content and sulfur content are prescribed | regulated in mass ppm.

Such mineral oil is one or two of solvent depressurization, solvent extraction, hydrocracking, hydrodehydration, solvent degassing, hydrorefining, sulfuric acid washing, and clay treatment with respect to lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of crude oil. It can obtain by combining suitably the refinement means more than a kind.

[Synthetic oil]

The synthetic oil consists of an organic compound containing two or more oxygen atoms in the molecule, and particularly preferably a compound having an ester bond and / or an ether bond. Specifically, although one kind or a mixture of two or more kinds of polyol esters, diesters and polyethers can be used, it is preferable to use polyol esters.

[Polyol ester]

As the polyol ester, esters of polyols having 3 to 20 diols or hydroxyl groups and fatty acids having 6 to 20 carbon atoms are preferably used. As the diol, specifically, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butane diol, 2-methyl-1,3-propanediol, 1,5- Pentanediol, neopentylglycol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol, 2-methyl-2-propyl-1,3-propane Diol, 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecandiol, 1,12-dode Candidi etc. are mentioned.

Moreover, as a polyol which has 3-20 hydroxyl groups, specifically, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, and di- (Pentaerythritol), tri- (pentaerythritol), glycerin, polyglycerol (2-20 monomers of glycerin), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol Polyhydric alcohols such as, arabitol, xylitol, mannitol, xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, serobiose, maltose, isomaltose, trehalose, Sugars such as sucrose, raffinose, gentianose, melezitose, and these partial ethers, and methylglycosides (glycosides).

Among these, as diol and polyol, neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, di- (pentaerythritol) And hindered alcohols such as tri- (pentaerythritol) are preferable.

Although the carbon number is not specifically limited in the fatty acid used for polyol ester, Usually, the C1-C24 thing is used. Among the fatty acids having 1 to 24 carbon atoms, from the viewpoint of lubricity, the carbon number is preferably 3 or more, more preferably 4 or more, still more preferably 5 or more, and particularly preferably 10 or more. Moreover, it is preferable that it is C18 or less from a viewpoint of compatibility with a refrigerant | coolant, It is more preferable that it is C12 or less, It is still more preferable that it is C10 or less, It is especially preferable that it is C9 or less.

Moreover, although any of linear fatty acid and branched fatty acid may be sufficient as this fatty acid, a linear fatty acid is preferable from a lubricity viewpoint, and a branched fatty acid is preferable from a hydrolytic stability viewpoint. As fatty acids, specifically, pentanic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid And octadecanoic acid, nonadecanoic acid, icosanoic acid, oleic acid, and the like, and these fatty acids may be either linear fatty acids or branched fatty acids, and fatty acids (neo acids) in which the α carbon atom is a quaternary carbon atom. It may be. Among these, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic acid), ferragonic acid (n-nonanoic acid), and ka Phthalic acid (n-decanoic acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid (3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid and 3 , 5,5-trimethylhexanoic acid is preferably used.

Among the polyol esters described above, esters of neopentyl polyol and monovalent fatty acids having 4 to 12 carbon atoms are particularly preferably used for the refrigerator oil of the present invention. Here, as neopentyl polyol which is a polyhydric alcohol which has a neopentyl structure, neopentyl glycol, trimethylol propane, pentaerythritol is used preferably, It is preferable to mix and use 2 or more types of neopentyl polyol especially. Moreover, as monovalent fatty acid, especially C5-C10 fatty acid and branched fatty acid are used preferably.

In addition, in this invention, as long as it has two or more ester groups, this polyol ester may be partial ester in which some of the hydroxyl groups which a polyol has remain without being esterified, the complete ester in which all the hydroxyl groups were esterified, and also the partial It may be a mixture of an ester and a full ester, but is preferably a full ester. When the residual amount of carboxyl groups is large, undesirable phenomena such as metal soap and the like are generated and reacted with the metals used in the refrigerator, so that the acid value is preferably 3 mgKOH / g or less, preferably 0.1 mgKOH. It is more preferable that it is / g or less. In addition, when there is much residual amount of hydroxyl groups, since an undesirable phenomenon arises, such as ester clouding at low temperature and blocking the capillary apparatus of a refrigeration cycle, it is preferable to set it as 50 mgKOH / g or less, It is more preferable that it is mgKOH / g or less.

[Diester]

As diester, ester of a C4-C14 polybasic acid and a C5-C18 alcohol is used preferably. Here, as a polybasic acid, adipic acid, azeline acid, sebacic acid, undecane diacid, dodecane diacid, etc. are mentioned specifically, Adipic acid, azeline acid, and sebacic acid are preferable.

Specific examples of the alcohol include 2-ethylhexanol, 3,5,5-trimethylhexanol, decyl alcohol, lauryl alcohol, oleyl alcohol, and the like. It is preferable to have a branched hydrocarbon group of 6-12, especially 8-10. Specifically, 2-ethylhexanol and 3,5,5-trimethylhexanol are preferable.

[Polyether]

The polyether is an organic compound having a plurality of ether bonds, and typically, an alkyl ether represented by the following formula (1) or (2), or a polyvinyl ether having a structural unit represented by the formula (3).

In the formula, R ¹ to R ⁵ each represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and A ^{1 to} A ³ are each composed of 5 to 300 alkylene oxide units having 1 or 2 or more carbon atoms of 2 to 4 carbon atoms. Represents a chain.

R ¹ to R ⁵ Is preferably hydrogen, a methyl group, an iso-propyl group, an iso-butyl group, or a tert-butyl group, and particularly preferably all are methyl groups. Regarding A ^{1 to} A ³ , as the alkylene oxide unit, an ethylene oxide unit or a propylene oxide unit is preferable, and the polymerization chain may be a block copolymer chain, a random copolymer chain or a mutual copolymer chain. The number of alkylene oxide units in the polymerization chain is set so that the viscosity of the polyether is within a predetermined range.

R <^6> , R <^7> and R <^8> represent a hydrogen atom or a C1-C8 hydrocarbon group, respectively, They may be same or different, R <^9> is a C1-C10 bivalent hydrocarbon group, R <^10> is C1-C8 20 is a hydrocarbon group, n is the number of the average value is 0~10, R ⁶ ~R ¹⁰ is in the case and may be the same or different and each respective unit, in addition R ⁹ O is plural, plural R ⁹ O May be the same or different.

As a specific polyether, polyalkylene glycol or its derivative (s), polyvinyl ether, etc. are mentioned, The polyalkylene glycol derivative or polyvinyl ether whose both terminal is an alkyl group is preferable.

〔Refrigerant〕

As the refrigerant used in the present invention, a hydrocarbon compound having a low molecular weight of 1 to 5 carbon atoms (preferably 2 to 4), specifically, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane And alkane compounds such as neopentane, and cycloparaffin compounds such as cyclopropane, cyclobutane, cyclopentane, and the like, and derivatives of the compounds (olefins corresponding to the above compounds) in which some carbon bonds are double bonds may also be used. Can be. As the refrigerant, these compounds may be used alone or in combination of two or more thereof as appropriate. Among them, propane or isobutane are particularly preferred.

[Refrigerator system]

The refrigerator system of the present invention is a refrigerator system in which a working fluid containing a refrigerant containing a C1-C5 hydrocarbon and a refrigerating oil is in contact with an organic polymer material in the refrigerating system, wherein the refrigerating oil has a mineral oil of 85 to 99 weight. % And 1 to 15% by weight of a synthetic oil composed of an organic compound containing two or more oxygen atoms in the molecule. The refrigerator system of the present invention includes, for example, a compressor, a condenser, an expansion mechanism (for example, an expansion valve), and an evaporator, and a working fluid containing a refrigerant and refrigerator oil is circulated in the system. The compressor is housed in the same housing as the electric motor for driving it, and is preferably used when the electric motor is lubricated and cooled by the working fluid. The working fluid is preferably a mixture of refrigerant and refrigeration oil at a weight ratio of 10:90 to 90:10, particularly 20:80 to 80:20.

In the electric motor, an organic polymer material is used for electrical insulation, and as the organic polymer material, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyphenylsulfide, polycaprolactam (nylon 6), polyhexa When methylene aziamide (nylon 66) or the like is used, particularly when polyethylene terephthalate or polybutylene terephthalate is used, the effect of the present invention becomes remarkable. In addition, the present invention can be adapted even when such an organic polymer material is used in addition to the electric motor.

[Other additives]

You may mix | blend another additive with the refrigerator oil of this invention suitably as needed. As the additive, 2,6-dibutylbutyl phenol, 2,6-dibutyl butyl-p-cresol, 4,4-methylene-bis- (2,6-dibutyl butyl-p-cresol), p, p Phenolic or amine-based antioxidants such as' -di-octyl-di-phenylamine, stabilizers such as phenylglycidyl ether, alkylglycidyl ether, phenylglycidyl ester, and alkylglycidyl ester, and tricre Extreme pressure agents such as phosphate, triphenyl phosphate, oil-based agents such as glycerin monooleate, glycerin monooleyl ether, glycerin monolauryl ether, metal deactivators such as benzotriazole, polydimethylsiloxane and polymethacrylate Antifoaming agents, an antifoaming agent, etc. are mentioned.

In addition, additives, such as a well-known clean dispersing agent, a viscosity index improver, a rust preventive agent, a corrosion inhibitor, a pour point depressant, can also be mix | blended as needed. These additives are mix | blended so that it may contain about 10 weight%-about 10 weight% normally in the lubricant of this invention. In particular, by adding about 0.01 to 0.5% by weight of the phenol-based or amine-based antioxidant, the stability and durability of the lubricant are greatly improved. In addition, phosphate esters such as tricresyl phosphate and triphenyl phosphate are useful as extreme pressure agents and effectively improve the lubrication characteristics such as crushing load and abrasion resistance by addition of a small amount (for example, 0.05 to 2.0 wt%). .

EXAMPLE

Although an Example is shown to the following and this invention is demonstrated in more detail, this invention is not restrict | limited to these specific examples.

As the base oil, paraffinic mineral oils 1, 2, naphthenic mineral oil and ester oil having the properties shown in Table 1 were used. Ester oil is ester synthesize | combined from 80 weight% of neopentyl glycol, 20 weight% of pentaerythritol, and the mixed polyol and 2-methyl hexanoic acid.

Paraffinic mineral oil1 Paraffinic mineral oil 2 Naphthenic mineral oil Ester oil Kinematic viscosity 40 ℃ (mm2 / s) 100 ℃ 8 2.2 22 4.3 12 2.7 10 2.5 Viscosity index 73 99 22 49 Sulfur (mass ppm) 365 1350 162 0 Nitrogen content (mass ppm) 0 4 5 0 Pour point (℃) -30 -30 Less than -50 Less than -50 n-d-M ring analysis% Ca% Cn% Cp  10 36 54  9 29 62  9 47 44  ---

These base oils were mix | blended in the compounding quantity shown to Tables 2 and 3, and the test oil 1-10 which becomes Examples 1-5 and Comparative Examples 1-5 was prepared.

Example 1 Example 2 Example 3 Example 4 Example 5 Announcement 1 Disclosure 2 Disclosure 3 Disclosure 4 Disclosure 5 Compounding amount (% by weight) Paraffinic mineral oil 1 99 95 90 - - Paraffinic mineral oil 2 - - - 95 - Naphthenic - - - - 95 Ester oil One 5 10 5 5 Precipitation amount (mg) 9 6 8 3 5 Capillary Blockage - none none - -

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Notice 6 Notice 7 Announcement 8 Disclosure 9 Disclosure 10 Compounding amount (% by weight) Paraffinic mineral oil 1 100 75 80 - - Paraffinic mineral oil 2 - - - 100 - Naphthenic - - - - 100 Ester oil - 25 20 - - Precipitation amount (mg) 16 22 12 18 13 Capillary Blockage Small quantity Small quantity - - -

[Oligomer Precipitation Test]

30 g of a test oil, 10 g of a hydrocarbon refrigerant (isobutane, R60Oa), and 1 g of PET (polyethylene terephthalate) film were put into a 100 mL capacity cylinder, and left for 14 days at 150 ° C using an autoclave. Thereafter, the amount of precipitates was measured by filtration of the test oil and the hydrocarbon refrigerant with a 0.8 µm pre-pore filter and an increase in weight. The result was shown to Tables 2 and 3 as the amount of precipitates.

Test oil 6-10 is 10 mg or more of precipitation amount of an oligomer. However, in the test oils 1-5, it is less than 10 mg, and it turns out that an oligomer becomes difficult to precipitate from PET.

[Capillary clogging test]

220 mL of the test oils 2, 3, 6, and 7 of Table 2, 3 were put into the refrigerator compressor as freezer oil, and 30 g of hydrocarbon refrigerants (isobutane, R60Oa) were used as a refrigerant. A condenser and a suction side were respectively connected to the discharge side of this refrigerator compressor, and a capillary was connected between the condenser and the evaporator, and the refrigeration system for evaluation was comprised. The compressor for refrigerators has a reciprocal compressor and the electric motor which drives it inside, and polyethylene terephthalate is used for insulation of an electric motor. The working fluid consisting of the refrigeration oil and the refrigerant is in direct contact with the electric motor for cooling. The compressor for refrigerators was continuously operated for 50,000 hours under conditions of a discharge pressure of 5 to 6 kg / cm 2 · G and a suction pressure of Okg / cm 2 · G. As a result, it evaluated whether the capillary blockage generate | occur | produced and it showed together in Table 2, 3 together.

Test oils 6 and 7 had a small amount of clogged capillary. However, capillary clogging did not occur in test oils 2 and 3.

[Industry availability]

Since the refrigeration oil for hydrocarbon refrigerants of this invention can suppress generation | occurrence | production of an oligomer by containing a predetermined amount of specific organic compounds in mineral oil, it can effectively prevent the capillary clogging and the opening / closing failure of a valve by an oligomer. It is very useful for long term stable operation of refrigeration system.

Since the refrigeration oil for hydrocarbon refrigerants of this invention can suppress generation | occurrence | production of an oligomer by containing a predetermined amount of a specific organic compound in mineral oil, the clogging of a capillary by an oligomer and the opening / closing failure of a valve can be prevented effectively. It has a special effect. Moreover, in the refrigerator system of this invention, such refrigeration oil is used and since generation | occurrence | production of an oligomer is suppressed, clogging of a capillary by an oligomer and generation | occurrence | production of the opening and closing of a valve are prevented effectively.

Claims (10)

As a refrigerant oil used in a refrigerator system in which a refrigerant containing hydrocarbons having 1 to 5 carbon atoms and a working fluid containing refrigerator oil are in contact with an organic polymer material inside the refrigerator system, A refrigeration oil for hydrocarbon refrigerant containing 85 to 99% by weight of mineral oil and 1 to 15% by weight of synthetic oil composed of an organic compound containing two or more oxygen atoms in a molecule. The method of claim 1, The refrigeration oil for hydrocarbon refrigerants in which the organic compound containing the oxygen atom of Claim 1 has an ester bond and / or an ether bond. The method of claim 1, The refrigeration oil for hydrocarbon refrigerants whose organic compound containing the oxygen atom of Claim 1 is polyol ester of neopentyl polyol and monovalent fatty acid of 4 to 12 carbon atoms. The method of claim 1, The refrigeration oil for hydrocarbon refrigerants whose refrigerant | coolant of Claim 1 is propane and / or isobutane. The method of claim 1, The refrigeration oil for hydrocarbon refrigerants whose organic polymer material of Claim 1 is polyethylene terephthalate and / or polybutylene terephthalate. A refrigeration system in which a refrigerant containing hydrocarbons having 1 to 5 carbon atoms and a working fluid containing refrigeration oil come into contact with an organic polymer material inside the refrigeration system, The refrigerator system is characterized in that the refrigerator oil contains 85 to 99% by weight of mineral oil and 1 to 15% by weight of synthetic oil composed of an organic compound containing two or more oxygen atoms in the molecule. The method of claim 6, The refrigerator system in which the organic compound containing the oxygen atom of Claim 6 has an ester bond and / or an ether bond. The method of claim 6, The refrigerator system of Claim 6 whose organic compound containing the oxygen atom of Claim 6 is neopentyl polyol and polyol ester of C4-C12 monovalent fatty acid. The method of claim 6, The refrigerator system according to claim 6, wherein the refrigerant according to claim 6 is propane and / or isobutane. The method of claim 6, A refrigerator system, wherein the organic polymer material according to claim 6 is polyethylene terephthalate and / or polybutylene terephthalate.