JP2015172205A - Lubricating-oil composition for compression-type refrigerating-machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating-oil composition for compression-type refrigerating-machine, that has an excellent thermal and chemical stability even when used in a compression-type refrigerating-machine in which a low carbon-number saturated fluorohydrocarbon cooling medium having a low global warming coefficient, is used.SOLUTION: Provided is a lubricating-oil composition for compression-type refrigerating-machine in which a cooling medium comprising a saturated fluorohydrocarbon having a carbon number of 1 to 3, is used, in which an oxygen-containing organic compound comprising at least one selected from polyoxyalkylene glycols, polyvinyl ethers, a poly(oxy)alkylene glycol or a copolymer between mono-ether thereof and polyvinyl ether, and polyol esters in any of which the water content is 500 mass ppm or less, is used as base oil.

Description

  The present invention relates to a lubricating oil composition for a compression type refrigerator, and more particularly, to a lubricating oil composition for a compression type refrigerator having a good thermal and oxidation stability using a saturated fluorinated hydrocarbon having a low carbon number as a refrigerant. is there.

In recent years, in compressor type refrigerators such as air conditioners and car air conditioners, saturated fluorinated hydrocarbons (HFC) having 1 or 2 carbon atoms, which are refrigerants that do not destroy the ozone layer, have been used. Recently, however, these compression refrigerators are increasingly used under severe conditions for a long time.
Therefore, a lubricating oil composition used for such a compression refrigerator is required to have excellent thermal and oxidation stability.

Conventionally, mixed refrigerants including difluoromethane (R32), such as R410A and R407C, have been used as HFC refrigerants that do not destroy the ozone layer in various compression refrigerators including air conditioners.
However, in addition to protecting the ozone layer, further prevention of global warming has been required, and therefore it has been desired to use a refrigerant containing more R32 having a low warming potential.
Since R32 has a relatively high theoretical COP and heat transfer coefficient and low pressure loss of the refrigerant, it has a characteristic of high energy efficiency when used in an air conditioner.
However, R32 has a characteristic that the discharge temperature of the compressor is about 20 ° C. higher than the conventional R410A and R407C.
Under such circumstances, research for improving the structure of the refrigeration apparatus has been conducted (for example, see Patent Document 1).

Further, a lubricating oil composition for compression refrigerating machines using these refrigerants requires a lubricating oil composition having high thermal and oxidation stability in the presence of those refrigerants.
However, unlike unsaturated HFCs and iodides, saturated HFCs are highly stable and can be addressed by blending existing antioxidants and acid scavengers used in R134a and the like. It was thought that it was possible (for example, refer patent documents 2-4). However, even when the existing antioxidants and acid scavengers were simply blended or the blending amount thereof was increased, the effect of increasing the thermal and oxidation stability was not satisfactory.

JP 2001-183020 A Japanese Patent Laid-Open No. 02-258896 JP 02-289898 A Japanese Patent Laid-Open No. 02-305893

  Under such circumstances, the present invention is a compression type excellent in thermal and oxidation stability even when used in a compression type refrigerator using a saturated fluorinated hydrocarbon refrigerant having a low carbon number and a low global warming potential. An object of the present invention is to provide a lubricating oil composition for a refrigerator.

As a result of intensive studies to achieve the above object, the present inventors have found that the object can be achieved by using an oxygen-containing organic compound whose water content is adjusted as a base oil. The present invention has been completed based on such findings.
That is, the present invention

1. All are selected from polyoxyalkylene glycols, polyvinyl ethers, poly (oxy) alkylene glycols or their monoether and polyvinyl ether copolymers, and polyol esters having a water content of 500 ppm by mass or less. A lubricating oil composition for a compression type refrigerator using a refrigerant containing a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, using at least one oxygen-containing organic compound as a base oil,
2. The oxygen-containing organic compound is represented by the following general formula (II)

(In the formula, R ⁴ , R ⁵ and R ⁶ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different, and R ⁷ has 2 carbon atoms. 10 is a divalent hydrocarbon group, R ⁸ is a hydrocarbon group having 1 to 10 carbon atoms, p is an average value of 0 to 10 and R ^{4 to} R ⁸ are the same for each structural unit. and or different respectively, and a plurality of R ^{7 O} in the case of R ^{7 O} there are a plurality may be the same or different.)
The lubricating oil composition for a compression type refrigerator as described in 1 above, wherein the main component is a polyvinyl compound having a structural unit represented by:
3. The lubricating oil composition for a compression type refrigerator as described in 1 or 2 above, which contains an antioxidant and / or an acid scavenger,
4). The lubricating oil composition for a compression refrigerator according to any one of 1 to 3, wherein the saturated fluorinated hydrocarbon having 1 to 3 carbon atoms is difluoromethane (R32),
5. The refrigerant is a mixture of difluoromethane (R32) and pentafluoroethane (R125), or difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2 tetrafluoroethane (R134a). And a lubricating oil composition for a compression refrigeration machine according to any one of the above 1 to 4, which is a mixture with
6). The lubricating oil composition for a compression refrigeration machine according to any one of 1 to 5, wherein the refrigerant is a refrigerant containing 70% by mass or more of difluoromethane (R32),
7). The lubricating oil composition for a compression refrigeration machine according to any one of 1 to 6, wherein the base oil has a kinematic viscosity at 100 ° C. of 1 mm ² / s to 50 mm ² / s,
8). The lubricating oil composition for a compression refrigeration machine according to any one of the above 1 to 7, wherein the number average molecular weight of the base oil is 300 or more and 3000 or less,
9. The lubricating oil composition for compression type refrigerators according to any one of 1 to 8 above, wherein the base oil has a viscosity index of 60 or more,
10. Furthermore, the lubricating oil composition for compression type refrigerators according to any one of the above 1 to 9, further comprising at least one additive selected from an extreme pressure agent, an oily agent, a metal deactivator and an antifoaming agent,
11. The lubricating oil composition for compression type refrigerators according to any one of the above 1 to 10, wherein the sliding part of the compression refrigerator is made of an engineering plastic, or has an organic coating film or an inorganic coating film,
12 The organic coating film is formed by using a polytetrafluoroethylene coating film, a polyimide coating film, a polyamideimide coating film, a resin base material composed of a polyhydroxy ether resin and a polysulfone resin, and a resin paint containing a crosslinking agent. The lubricating oil composition for a compression type refrigerator as described in 11 above, which is one of curable insulating films,
13. 12. The lubricating oil composition for a compression type refrigerator as described in 11 above, wherein the inorganic coating film is any one of a graphite film, a diamond-like carbon film, a tin film, a chromium film, a nickel film, and a molybdenum film.
14 Lubricating oil composition for compression type refrigerators as described in any one of said 1-13 used for a car air conditioner, an electric car air conditioner, a gas heat pump, an air conditioner, a refrigerator, a vending machine, a showcase, a hot water supply system, or a freezing / heating system object,
15. 15. The lubricating oil composition for a compression type refrigerator as described in 14 above, wherein the water content in the system is 300 mass ppm or less and the residual air partial pressure is 10 kPa or less,
Is to provide.

  According to the present invention, even when used in a compression refrigeration machine using a low carbon number saturated fluorinated hydrocarbon refrigerant having a low global warming potential, the lubricating oil for the compression refrigeration machine is excellent in thermal and chemical stability. A composition can be provided.

  The present invention relates to a lubricating oil composition for a compression type refrigerator using a refrigerant containing a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, using an oxygen-containing organic compound having a water content of 500 ppm by mass or less as a base oil. is there.

<Base oil>
The base oil used in the present invention is an oxygen-containing organic compound having a water content of 500 mass ppm or less.
If an oxygen-containing organic compound with a water content exceeding 500 ppm by mass is used as the base oil, the heat and chemical stability of the refrigerating machine oil will be reduced, and at the same time the refrigerant will be altered and deteriorated. There is. That is, the so-called refrigerating machine fluid composition formed by the refrigerant and the lubricating oil composition for the refrigerating machine is deteriorated and deteriorated at an early stage.
Therefore, the water content of the oxygen-containing organic compound is preferably 300 ppm by mass or less, more preferably 200 ppm by mass or less, and particularly preferably 100 ppm by mass or less.

<Oxygen-containing organic compound>
The oxygen-containing organic compound used as the base oil of the present invention is selected from polyoxyalkylene glycols, polyvinyl ethers, poly (oxy) alkylene glycol or a copolymer of its monoether and polyvinyl ether, and polyol esters. An oxygen-containing organic compound consisting of at least one kind.

[Polyoxyalkylene glycols]
Examples of polyoxyalkylene glycols that can be used as the base oil include compounds represented by general formula (I).
_{^{R 1 - [(OR 2)}} m -OR 3] n ··· (I)
(In the formula, R ¹ is a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, a hydrocarbon group having 1 to 10 carbon atoms having 2 to 6 bonding parts, or An oxygen-containing hydrocarbon group having 1 to 10 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, R ³ is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or carbon (The oxygen-containing hydrocarbon group of formula 1 to 10, n is an integer of 1 to 6, and m is a number with an average value of m × n of 6 to 80.)

In the general formula (I), the monovalent hydrocarbon group having 1 to 10 carbon atoms in each of R ¹ and R ³ may be linear, branched or cyclic. The hydrocarbon group is preferably an alkyl group, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, Various nonyl groups, various decyl groups, cyclopentyl groups, cyclohexyl groups and the like can be mentioned. When the alkyl group has more than 10 carbon atoms, the compatibility with the refrigerant is lowered, and phase separation may occur. The carbon number of a preferable alkyl group is 1-6.
The hydrocarbon group portion of the acyl group having 2 to 10 carbon atoms in each of R ¹ and R ³ may be linear, branched or cyclic. The hydrocarbon group portion of the acyl group is preferably an alkyl group, and specific examples thereof include the same various groups having 1 to 9 carbon atoms as specific examples of the alkyl group. When the acyl group has more than 10 carbon atoms, the compatibility with the refrigerant is lowered, and phase separation may occur. A preferable acyl group has 2 to 6 carbon atoms.
When R ¹ and R ³ are both hydrocarbon groups or acyl groups, R ¹ and R ³ may be the same or different from each other.

Furthermore, when n is 2 or more, a plurality of R ^{3 in} one molecule may be the same or different.
When R ¹ is a hydrocarbon group having 1 to 10 carbon atoms having 2 to 6 bonding sites, the hydrocarbon group may be a chain or a cyclic one. The hydrocarbon group having two bonding sites is preferably an aliphatic hydrocarbon group, for example, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, cyclopentylene group. Examples thereof include a len group and a cyclohexylene group. Examples of other hydrocarbon groups include residues obtained by removing hydroxyl groups from bisphenols such as biphenol, bisphenol F, and bisphenol A. Further, the hydrocarbon group having 3 to 6 binding sites is preferably an aliphatic hydrocarbon group, for example, trimethylolpropane, glycerin, pentaerythritol, sorbitol, 1,2,3-trihydroxycyclohexane, 1,3,3. Examples thereof include a residue obtained by removing a hydroxyl group from a polyhydric alcohol such as 5-trihydroxycyclohexane.
When the number of carbon atoms of the aliphatic hydrocarbon group exceeds 10, compatibility with the refrigerant may be reduced, and phase separation may occur. A preferable carbon number is 2-6.

Furthermore, examples of the oxygen-containing hydrocarbon group having 1 to 10 carbon atoms in each of R ¹ and R ³ include a chain aliphatic group having a ether bond and a cyclic aliphatic group. A furfuryl group is preferred.
In the present invention, at least one of R ¹ and R ³ is preferably an alkyl group, particularly an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group from the viewpoint of viscosity characteristics. Furthermore, for the same reason as described above, it is preferable that both R ¹ and R ³ are alkyl groups, particularly methyl groups.

R ² in the general formula (I) is an alkylene group having 2 to 4 carbon atoms, and examples of the oxyalkylene group of the repeating unit include an oxyethylene group, an oxypropylene group, and an oxybutylene group. The oxyalkylene groups in one molecule may be the same or two or more oxyalkylene groups may be contained, but those containing at least an oxypropylene unit in one molecule are preferred, and in particular, oxyalkylene units. Those containing 50 mol% or more of oxypropylene units are preferred.
N in the general formula (I) in an integer of 1 to 6, it is determined in accordance with the number of binding sites of R ^1. For example, when R ¹ is an alkyl group or an acyl group, n is 1, and when R ¹ is an aliphatic hydrocarbon group having 2, 3, 4, 5, and 6 binding sites, n is 2, 3 respectively. , 4, 5 and 6. In addition, m is a number such that the average value of m × n is 6 to 80, and if the average value exceeds 80, the compatibility may be lowered and the oil return property may be deteriorated. However, if it deviates from the above range, the object of the present invention cannot be sufficiently achieved.

  Among the polyoxyalkylene glycols represented by the general formula (I), the general formula (Ia)

(In the formula, x represents a number of 6 to 80.)
Polyoxypropylene glycol dimethyl ether represented by the general formula (Ib)

(In the formula, a and b each represent a number of 1 or more and a total of 6 to 80)
Polyoxyethylene polyoxypropylene glycol dimethyl ether represented by the formula is preferred.
As the polyoxyalkylene glycols represented by the above general formula (I), any of those described in detail in JP-A-2-305893 can be used.
In this invention, these polyoxyalkylene glycols may be used individually by 1 type, and may be used in combination of 2 or more type.

The polyoxyalkylene glycol derivative was obtained, for example, by polymerizing an alkylene oxide having 2 to 4 carbon atoms such as ethylene oxide or propylene oxide using water or alkali hydroxide as an initiator to obtain a polyoxyalkylene glycol having hydroxyl groups at both ends. Thereafter, both ends of this hydroxyl group can be obtained by etherification or esterification using alkyl halide or acyl halide.
Moreover, C1-C10 monohydric alcohol or its alkali metal salt is used as an initiator, C2-C4 alkylene oxide is polymerized, it has an ether bond in one terminal, and the other terminal is a hydroxyl group It can also be produced by obtaining a polyoxyalkylene glycol monoalkyl ether, and then etherifying or esterifying the hydroxyl group. In addition, when manufacturing the compound whose n is 2 or more by general formula (I), it may replace with monohydric alcohol and should just use 2-6 valent polyhydric alcohol as an initiator.

  When producing a polyoxyalkylene glycol derivative by such a method, the amount of alkyl halide or acyl halide is such that the ratio of polyoxyalkylene glycol or the like to alkyl halide or acyl halide in the etherification or esterification reaction is When the amount is less than the stoichiometric amount, the hydroxyl group remains and the hydroxyl value increases. Therefore, it is desirable to optimize the molar ratio of polyoxyalkylene glycol or the like to alkyl halide or acyl halide. Moreover, coloring can be suppressed by performing superposition | polymerization, etherification, and esterification reaction in inert gas atmosphere.

[Polyvinyl ethers]
In the refrigerating machine oil composition of the present invention, the polyvinyl ethers that can be used as the base oil include those represented by the general formula (II)

The main component is a polyvinyl compound having a structural unit represented by:
R ⁴ , R ⁵ and R ⁶ in the general formula (II) each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different. The hydrocarbon group is specifically a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups. Groups, various heptyl groups, various octyl groups and other alkyl groups; cyclopentyl groups, cyclohexyl groups, various methylcyclohexyl groups, various ethylcyclohexyl groups, various dimethylcyclohexyl groups and other cycloalkyl groups; phenyl groups, various methylphenyl groups, various ethyl groups An aryl group such as a phenyl group and various dimethylphenyl groups; an arylalkyl group such as a benzyl group, various phenylethyl groups, and various methylbenzyl groups. R ⁴ , R ⁵ and R ⁶ are particularly preferably a hydrogen atom or a hydrocarbon group having 3 or less carbon atoms.

On the other hand, R ⁷ in the general formula (II) represents a divalent hydrocarbon group having 2 to 10 carbon atoms. Specifically, the divalent hydrocarbon group having 2 to 10 carbon atoms is specifically, Ethylene group, phenylethylene group, 1,2-propylene group, 2-phenyl-1,2-propylene group, 1,3-propylene group, various butylene groups, various pentylene groups, various hexylene groups, various heptylene groups, various octylenes Groups, divalent aliphatic hydrocarbon groups such as various nonylene groups and various decylene groups; alicyclic rings having two bonding sites on cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, and propylcyclohexane Formula hydrocarbon group; various phenylene groups, various methylphenylene groups, various ethylphenylene groups, various dimethylphenylene groups, various naphthylenes, etc. Divalent aromatic hydrocarbon groups of alkyl aromatic hydrocarbon groups such as toluene and ethylbenzene, and alkyl aromatic hydrocarbon groups each having a monovalent bonding site on the aromatic portion; polyalkylene such as xylene and diethylbenzene Examples thereof include an alkyl aromatic hydrocarbon group having a bonding site in the alkyl group portion of the alkyl aromatic hydrocarbon. Of these, an aliphatic hydrocarbon group having 2 to 4 carbon atoms is particularly preferred. The plurality of R ⁷ Os may be the same or different.
In addition, p in general formula (II) shows the number of repetitions, The average value is 0-10, Preferably it is the number of the range of 0-5.

Further, R ⁸ in the general formula (II) represents a hydrocarbon group having 1 to 10 carbon atoms, and specifically, this hydrocarbon group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, n -Alkyl groups such as butyl group, isobutyl group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups; cyclopentyl group, cyclohexyl group , Various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl groups, various cycloalkyl groups such as dimethylcyclohexyl groups; phenyl groups, various methylphenyl groups, various ethylphenyl groups, various dimethylphenyl groups, various propylphenyl groups, various types Trimethylphenyl group, various butylphenyl groups, various naphthyl groups Aryl groups such as a group; arylalkyl groups such as a benzyl group, various phenylethyl groups, various methylbenzyl groups, various phenylpropyl groups, and various phenylbutyl groups; Among these, a hydrocarbon group having 8 or less carbon atoms is preferable. When p is 0, an alkyl group having 1 to 6 carbon atoms is particularly preferable, and when p is 1 or more, an alkyl group having 1 to 4 carbon atoms is particularly preferable.

Among the polyvinyl compounds having the structural unit represented by the general formula (II), R ⁴ , R ⁵ and R ⁶ are all hydrogen atoms, p is 0, and R ⁸ is an ethyl group. 50 to 100 mol%, the polymer or copolymer ^{R 8} contains 0-50 mol% of structural units is an alkyl group having 3 or 4 carbon atoms are preferred.
The proportion of the structural unit in which R ⁸ is an ethyl group is more preferably 70 to 100 mol%, and more preferably 100 mol%, that is, polyethyl vinyl ether.
Further, as the alkyl group having 3 or 4 carbon atoms of R ⁸ , n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and tert-butyl group can be used. Is preferred.

  The polyvinyl ether compound of the present invention can be produced by polymerization of a corresponding vinyl ether monomer. The vinyl ether monomers that can be used here are those represented by the general formula (III)

(In the formula, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and p are the same as above.)
It is represented by Examples of the vinyl ether monomer include various compounds corresponding to the polyvinyl ether compound, such as vinyl methyl ether, vinyl ethyl ether, vinyl n-propyl ether, vinyl isopropyl ether, vinyl n-butyl ether, Vinyl-isobutyl ether, vinyl-sec-butyl ether, vinyl-tert-butyl ether, vinyl-n-pentyl ether, vinyl-n-hexyl ether, vinyl-2-methoxyethyl ether, vinyl-2-ethoxyethyl ether, vinyl-2 -Methoxy-1-methyl ethyl ether, vinyl-2-methoxy-propyl ether, vinyl-3,6-dioxaheptyl ether, vinyl-3,6,9-trioxadecyl ether, vinyl-1,4-dimethyl- 3 6-dioxaheptyl ether, vinyl-1,4,7-trimethyl-3,6,9-trioxadecyl ether, vinyl-2,6-dioxa-4-heptyl ether, vinyl-2,6,9-trioxa -4-decyl ether, 1-methoxypropene, 1-ethoxypropene, 1-n-propoxypropene, 1-isopropoxypropene, 1-n-butoxypropene, 1-isobutoxypropene, 1-sec-butoxypropene, 1 -Tert-butoxypropene, 2-methoxypropene, 2-ethoxypropene, 2-n-propoxypropene, 2-isopropoxypropene, 2-n-butoxypropene, 2-isobutoxypropene, 2-sec-butoxypropene, 2 -Tert-butoxypropene, 1-methoxy-1-butene, 1-ethoxy -1-butene, 1-n-propoxy-1-butene, 1-isopropoxy-1-butene, 1-n-butoxy-1-butene, 1-isobutoxy-1-butene, 1-sec-butoxy-1- Butene, 1-tert-butoxy-1-butene, 2-methoxy-1-butene, 2-ethoxy-1-butene, 2-n-propoxy-1-butene, 2-isopropoxy-1-butene, 2-n -Butoxy-1-butene, 2-isobutoxy-1-butene, 2-sec-butoxy-1-butene, 2-tert-butoxy-1-butene, 2-methoxy-2-butene, 2-ethoxy-2-butene 2-n-propoxy-2-butene, 2-isopropoxy-2-butene, 2-n-butoxy-2-butene, 2-isobutoxy-2-butene, 2-sec-butoxy-2-butene, 2 -Tert-butoxy-2-butene and the like. These vinyl ether monomers can be produced by known methods.

The terminal of the polyvinyl ether compound having the structural unit represented by the general formula (II) used in the refrigerating machine oil composition of the present invention is converted into a desired structure by the method shown in the present disclosure example and a known method. can do. Examples of the group to be converted include saturated hydrocarbon groups, ether groups, alcohol groups, ketone groups, amide groups, and nitrile groups.
As the polyvinyl ether compound used for the base oil in the refrigerating machine oil composition of the present invention, those having the following terminal structure are suitable. That is,
(1) One terminal is represented by the general formula (IV)

(Wherein R ⁹ , R ¹⁰ and R ¹¹ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different, and R ¹² represents a carbon number. A divalent hydrocarbon group of 2 to 10, R ¹³ is a hydrocarbon group having 1 to 10 carbon atoms, q represents a number having an average value of 0 to 10, and when there are a plurality of R ¹² O, a plurality of R ^{12 12} O may be the same or different.
And the remaining ends are represented by the general formula (V)

(Wherein R ¹⁴ , R ¹⁵ and R ¹⁶ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different, and R ¹⁷ represents a carbon number. A divalent hydrocarbon group of 2 to 10, R ¹⁸ is a hydrocarbon group having 1 to 10 carbon atoms, r represents a number having an average value of 0 to 10, and when there are a plurality of R ¹⁷ O, a plurality of R ^{17 17} O may be the same or different.
Having a structure represented by
(2) One terminal is represented by the general formula (IV), and the other terminal is the general formula (VI).

(In the formula, R ¹⁹ , R ²⁰ and R ²¹ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different, and R ²² and R ²⁴ may be the same. Each represents a divalent hydrocarbon group having 2 to 10 carbon atoms, which may be the same or different, and R ²³ and R ²⁵ each represent a hydrocarbon group having 1 to 10 carbon atoms. , They may be the same or different, and s and t each represent an average value of 0 to 10, and they may be the same or different, and When there are R ²² Os, the plurality of R ²² Os may be the same or different, and when there are a plurality of R ²⁴ Os, the plurality of R ^24s may be the same or different. May be.)
Having a structure represented by
(3) One end of which is represented by the general formula (IV) and the other end has an olefinically unsaturated bond,
(4) One terminal is represented by the general formula (IV), and the other terminal is the general formula (VII).

(In the formula, R ²⁶ , R ²⁷ and R ²⁸ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different.)
It has a structure represented by
The polyvinyl ether-based mixture may be a mixture of two or more selected from those having the terminal structures (1) to (4). Preferred examples of such a mixture include a mixture of the above (1) and (4), and a mixture of (2) and (3).

As the polyvinyl ether compound, it is preferable to select the raw materials, the initiator and the reaction conditions so as to produce a polyvinyl ether compound having a preferable viscosity range. In addition, it is also possible to adjust the viscosity within the kinematic viscosity range by mixing the polymer outside the kinematic viscosity range with a polymer having another kinematic viscosity.
In the production of the polyvinyl ether compound of the present invention, it is desirable to remove the unreacted raw material compound after completion of the synthesis reaction and further perform a dehydration treatment to reduce the moisture as much as possible.
In this invention, this polyvinyl ether type compound may be used individually by 1 type, and may be used in combination of 2 or more type.

[Copolymer of poly (oxy) alkylene glycol or its monoether and polyvinyl ether]
Poly (oxy) alkylene glycol refers to both polyalkylene glycol and polyoxyalkylene glycol.
In the refrigerating machine oil composition of the present invention, the copolymer of poly (oxy) alkylene glycol or its monoether and polyvinyl ether that can be used as a base oil includes general formula (VIII) and general formula (IX).

(Hereinafter, referred to as polyvinyl ether copolymer I and polyvinyl ether copolymer II), respectively.
In the general formula (VIII), R ²⁹ , R ³⁰ and R ³¹ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, which may be the same or different, and R ³³ has 2 carbon atoms. -4 divalent hydrocarbon group, R ³⁴ is an aliphatic or alicyclic hydrocarbon group having 1 to 20 carbon atoms, an aromatic hydrocarbon group which may have a substituent having 1 to 20 carbon atoms, carbon An acyl group having 2 to 20 carbon atoms or an oxygen-containing hydrocarbon group having 2 to 50 carbon atoms, R ³² represents a hydrocarbon group having 1 to 10 carbon atoms, and R ³⁴ , R ³³ , and R ³² are a plurality of them. May be the same or different.
Here, the hydrocarbon group having 1 to 8 carbon atoms of R ^{29 to} R ³¹ is specifically a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, sec- Alkyl groups such as butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups; cyclopentyl group, cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, various dimethylcyclohexyl groups, various An aryl group such as a dimethylphenyl group; an arylalkyl group such as a benzyl group, various phenylethyl groups, and various methylbenzyl groups. In addition, as each of these R <^29> , R <^30> and R < ³¹ >, a hydrogen atom is especially preferable.

On the other hand, examples of the divalent hydrocarbon group having 2 to 4 carbon atoms represented by R ³³ include divalent alkylene groups such as a methylene group, an ethylene group, a propylene group, a trimethylene group, and various butylene groups. .
In addition, v in general formula (VIII) shows the repeating number of R ^<33 > O, The average value is 1-50, Preferably it is 1-20, More preferably, it is 1-10, Most preferably, it is the range of 1-5. Is a number. When the R ^{33 O} is plural, plural R ^{33 O} may be the same or different.
K is 1-50, preferably 1-10, more preferably 1-2, particularly preferably 1, u is 0-50, preferably 2-25, more preferably 5-15, If there are a plurality of k and u, each of them may be block or random.

Furthermore, R ³⁴ in formula (VIII) preferably represents an alkyl group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or an oxygen-containing hydrocarbon group having 2 to 50 carbon atoms.
Specific examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, and various pentyl groups. Group, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, cyclopentyl groups, cyclohexyl groups, various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl groups, various dimethylcyclohexyl groups, etc. .
Examples of the acyl group having 2 to 10 carbon atoms include acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, piperoyl group, benzoyl group, and toluoyl group.
Further, specific examples of the oxygen-containing hydrocarbon group having 2 to 50 carbon atoms include methoxymethyl group, methoxyethyl group, methoxypropyl group, 1,1-bismethoxypropyl group, 1,2-bismethoxypropyl group, ethoxy A propyl group, a (2-methoxyethoxy) propyl group, a (1-methyl-2-methoxy) propyl group and the like can be preferably exemplified.

In the general formula (VIII), the hydrocarbon group having 1 to 10 carbon atoms represented by R ³² specifically includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. Alkyl groups such as various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups; cyclopentyl groups, cyclohexyl groups, various methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl groups, Cycloalkyl groups such as various dimethylcyclohexyl groups; aryl groups such as phenyl groups, various methylphenyl groups, various ethylphenyl groups, various dimethylphenyl groups, various propylphenyl groups, various trimethylphenyl groups, various butylphenyl groups, and various naphthyl groups Benzyl group, various phenylethyl groups , Arylmethyl groups such as various methylbenzyl groups, various phenylpropyl groups, and various phenylbutyl groups.
R ^{29 to} R ³¹ , R ³⁴ , R ³³ and v and R ^{29 to} R ³² may be the same or different for each structural unit.

  By making the polyvinyl ether copolymer I having the structural unit represented by the general formula (VIII) into a copolymer, it is possible to improve lubricity, insulation, hygroscopicity, etc. while satisfying compatibility. There is an effect that can be done. At this time, by selecting the kind of raw material monomer, the kind of initiator, and the ratio of the copolymer, the performance of the oil can be adjusted to the target level. Therefore, there is an effect that an oil agent can be freely obtained in accordance with requirements such as lubricity and compatibility that differ depending on the type of compressor, the material of the lubrication part, the refrigerating capacity, the type of refrigerant, and the like in the refrigeration system or the air conditioning system.

On the other hand, in the polyvinyl ether copolymer II represented by the general formula (IX), R ^{29 to} R ³² , R ³³ and v are the same as described above. R ³³ and R ³² may be the same or different when there are a plurality of them. x and y each represent a number from 1 to 50, and when there are a plurality of x and y, each may be a block or random. X and Y each independently represent a hydrogen atom, a hydroxyl group or 1 to 20 hydrocarbon groups.

The method for producing the polyvinyl ether copolymer I represented by the general formula (VIII) is not particularly limited as long as it is a method by which it can be obtained. Can be manufactured.
(Production method 1 of polyvinyl ether copolymer I)
In this production method 1, the general formula (X)
R ³⁴ — (OR ³³ ) _v —OH (X)
(In the formula, R ³³ , R ³⁴ and v are the same as described above.)
A poly (oxy) alkylene glycol compound represented by formula (XI):

(Wherein R ^{29 to} R ³² are the same as described above.)
By polymerizing a vinyl ether compound represented by the formula (I), a polyvinyl ether copolymer I can be obtained.
Examples of the poly (oxy) alkylene glycol compound represented by the general formula (X) include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol. And (oxy) alkylene glycol monoethers such as monomethyl ether.
Examples of the vinyl ether compound represented by the general formula (XI) include vinyl methyl ether, vinyl ethyl ether, vinyl n-propyl ether, vinyl isopropyl ether, vinyl n-butyl ether, vinyl isobutyl ether, Vinyl ethers such as vinyl-sec-butyl ether, vinyl-tert-butyl ether, vinyl-n-pentyl ether, vinyl-n-hexyl ether; 1-methoxypropene, 1-ethoxypropene, 1-n-propoxypropene, 1-iso Propoxypropene, 1-n-butoxypropene, 1-isobutoxypropene, 1-sec-butoxypropene, 1-tert-butoxypropene, 2-methoxypropene, 2-ethoxypropene, 2-n-propoxypropene, 2 Propenes such as isopropoxypropene, 2-n-butoxypropene, 2-isobutoxypropene, 2-sec-butoxypropene, 2-tert-butoxypropene; 1-methoxy-1-butene, 1-ethoxy-1-butene 1-n-propoxy-1-butene, 1-isopropoxy-1-butene, 1-n-butoxy-1-butene, 1-isobutoxy-1-butene, 1-sec-butoxy-1-butene, 1- tert-butoxy-1-butene, 2-methoxy-1-butene, 2-ethoxy-1-butene, 2-n-propoxy-1-butene, 2-isopropoxy-1-butene, 2-n-butoxy-1 -Butene, 2-isobutoxy-1-butene, 2-sec-butoxy-1-butene, 2-tert-butoxy-1-butene, 2-methoxy-2-butene 2-ethoxy-2-butene, 2-n-propoxy-2-butene, 2-isopropoxy-2-butene, 2-n-butoxy-2-butene, 2-tert-butoxy-2-butene, etc. Butenes. These vinyl ether monomers can be produced by a known method.

(Method 2 for producing polyvinyl ether copolymer I)
In this production method 2, the general formula (XII)

(Wherein R ^{29 to} R ³⁴ and v are the same as described above.)
The polyvinyl ether copolymer I can be obtained by polymerizing the vinyl ether compound represented by the general formula (XI) using the acetal compound represented by formula (II) as an initiator.
Examples of the acetal compound represented by the general formula (XII) include acetaldehyde methyl (2-methoxyethyl) acetal, acetaldehyde ethyl (2-methoxyethyl) acetal, acetaldehyde methyl (2-methoxy 1-methylethyl) acetal, and acetaldehyde. Ethyl (2-methoxy-1-methylethyl) acetal, acetaldehyde methyl [2- (2-methoxyethoxy) ethyl] acetal, acetaldehyde ethyl [2- (2-methoxyethoxy) ethyl] acetal, acetaldehyde methyl [2- (2 -Methoxyethoxy) -1-methylethyl] acetal, acetaldehyde ethyl [2- (2-methoxyethoxy) -1-methylethyl] acetal, and the like.
The acetal compound represented by the general formula (XII) includes, for example, one molecule of a poly (oxy) alkylene glycol compound represented by the general formula (X) and a vinyl ether type represented by the general formula (XI). It can also be produced by reacting one molecule of the compound. The obtained acetal compound can be isolated or used as it is as an initiator.

(Method 3 for producing polyvinyl ether copolymer I)
In this production method 3, the general formula (XIII)

(Wherein R ^{29 to} R ³¹ , R ³³ , R ³⁴ and v are the same as described above.)
The polyvinyl ether copolymer I can be obtained by polymerizing the vinyl ether compound represented by the general formula (XI) using the acetal compound represented by formula (II) as an initiator.
Examples of the acetal compound represented by the general formula (XIII) include acetaldehyde di (2-methoxyethyl) acetal, acetaldehyde di (2-methoxy-1-methylethyl) acetal, acetaldehyde di [2- (2-methoxyethoxy ) Ethyl] acetal, acetaldehyde di [2- (2-methoxyethoxy) -1-methylethyl] acetal, and the like.
The acetal compound represented by the general formula (XIII) includes, for example, one molecule of a poly (oxy) alkylene glycol compound represented by the general formula (X) and the general formula (XIV).

(Wherein R ^{29 to} R ³¹ , R ³³ , R ³⁴ and v are the same as described above.)
It can also be produced by reacting with one molecule of a vinyl ether compound represented by the formula: The obtained acetal compound can be isolated or used as it is as an initiator.
One end of the vinyl ether copolymer I represented by the general formula (VIII) is represented by the general formula (XV) or (XVI).

(Wherein R ^{29 to} R ³⁴ and v are the same as described above.)
And the remaining ends are represented by the general formula (XVII) or the general formula (XVIII).

(Wherein R ^{29 to} R ³⁴ and v are the same as described above.)
It can be set as the polyvinyl ether type copolymer I which has a structure represented by these.
Among such polyvinyl ether copolymers I, the following are particularly suitable as base oils for the refrigerating machine oil composition of the present invention.
(1) One end thereof is represented by the general formula (XV) or (XVI), and the other end has a structure represented by the general formula (XVII) or (XVIII), in the general formula (VIII) R ²⁹ , R ³⁰ and R ³¹ are both hydrogen atoms, v is a number of 1 to 4, R ³³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, R ³⁴ is an alkyl group having 1 to 10 carbon atoms, and R ³² is a hydrocarbon group having 1 to 10 carbon atoms.
(2) One terminal is represented by the general formula (XV) and the other terminal is represented by the general formula (XVIII), and R ²⁹ , R ³⁰ and R ³¹ in the general formula (VIII) Are both hydrogen atoms, v is a number of 1 to 4, R ³³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, R ³⁴ is an alkyl group having 1 to 10 carbon atoms, and R ³² is a group having 1 to 10 carbon atoms. A hydrocarbon group.
(3) One terminal thereof is represented by the general formula (XVI) and the other terminal is represented by the general formula (XVII), and R ²⁹ , R ³⁰ and R ³¹ in the general formula (VIII). Are both hydrogen atoms, v is a number of 1 to 4, R ³³ is a divalent hydrocarbon group having 2 to 4 carbon atoms, R ³⁴ is an alkyl group having 1 to 10 carbon atoms, and R ³² is a group having 1 to 10 carbon atoms. A hydrocarbon group.

On the other hand, the method for producing the polyvinyl ether copolymer II represented by the general formula (IX) is not particularly limited as long as it is a method by which it can be obtained, but it can be efficiently produced by the method described below. can do.
(Production method of polyvinyl ether copolymer II)
The polyvinyl ether copolymer II represented by the general formula (IX) is represented by the general formula (XIX).
HO- (R ³³ O) _v -H (XIX)
(Wherein R ³³ and v are the same as described above.)
It can obtain by polymerizing the vinyl ether compound represented by the said general formula (XI), using poly (oxy) alkylene glycol represented by these as an initiator.
Examples of the poly (oxy) alkylene glycol represented by the general formula (XIX) include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, and polypropylene glycol.
In the present invention, this poly (oxy) alkylene glycol or a copolymer of its monoether and polyvinyl ether may be used singly or in combination of two or more.

[Polyol esters]
In the refrigerating machine oil composition of the present invention, as a polyol ester that can be used as a base oil, an ester of a diol or a polyol having about 3 to 20 hydroxyl groups and a fatty acid having about 1 to 24 carbon atoms is preferably used. .
Here, as the diol, for example, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 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-propanediol 2,2-diethyl-1,3-propanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, etc. Can be mentioned.

  Examples of the polyol include trimethylolethane, trimethylolpropane, trimethylolbutane, di- (trimethylolpropane), tri- (trimethylolpropane), pentaerythritol, di- (pentaerythritol), and tri- (pentaerythritol). ), Glycerin, polyglycerin (2-20 mer of glycerin), 1,3,5-pentanetriol, sorbitol, sorbitan, sorbitol glycerin condensate, polyhydric alcohols such as adonitol, arabitol, xylitol, mannitol; xylose, arabinose Ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose, Nchianosu, saccharides such as Merenjitosu; and their partially etherified products and methyl glucosides (glycosides) and the like. Among these, as the polyol, neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, di- (pentaerythritol), tri Hindered alcohols such as-(pentaerythritol) are preferred.

As the fatty acid, the number of carbon atoms is not particularly limited, but those having 1 to 24 carbon atoms are usually used. Among the fatty acids having 1 to 24 carbon atoms, those having 3 or more carbon atoms are preferable, those having 4 or more carbon atoms are more preferable, those having 5 or more carbon atoms are even more preferable, and those having 10 or more carbon atoms are more preferable. The above is most preferable. Moreover, from a compatible point with a refrigerant | coolant, a C18 or less thing is preferable, a C12 or less thing is more preferable, and a C9 or less thing is still more preferable.
Moreover, any of a linear fatty acid and a branched fatty acid may be sufficient, a linear fatty acid is preferable from the point of lubricity, and a branched fatty acid is preferable from the point of hydrolysis stability. Furthermore, either saturated fatty acid or unsaturated fatty acid may be used.

Specific examples of the fatty acid include, for example, pentanoic 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. Examples thereof include linear or branched acids such as acids, nonadecanoic acid, icosanoic acid, and oleic acid; or so-called neoacids in which the α carbon atom is quaternary. More specifically, valeric acid (n-pentanoic acid), caproic acid (n-hexanoic acid), enanthic acid (n-heptanoic acid), caprylic acid (n-octanoic acid), pelargonic acid (n-nonanoic acid) Capric acid (n-decanoic acid), oleic acid (cis-9-octadecenoic acid), isopentanoic acid (3-methylbutanoic acid), 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, 3, 5,5-trimethylhexanoic acid and the like are preferable.
The polyol ester may be a partial ester remaining without all the hydroxyl groups of the polyol being esterified, or may be a complete ester in which all the hydroxyl groups are esterified, or a partial ester and a complete ester. A complete ester is preferable.

  Among these polyol esters, since they are more excellent in hydrolysis stability, neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythris More preferred are esters of hindered alcohols such as lithol, di- (pentaerythritol), tri- (pentaerythritol), and further esters of neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane and pentaerythritol. The ester of pentaerythritol is the most preferable because it is particularly excellent in compatibility with the refrigerant and hydrolytic stability.

  Specific examples of preferred polyol esters include neopentyl glycol, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, Diester of one or more fatty acids selected from 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; trimethylolethane and valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid , One or more fatty acids selected from capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and Triesters: Trimethylolpropane, valeric acid, caproic acid, enanthic acid, capryl , One or more selected from pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid Trimethylolbutane with valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2- Triester with one or more fatty acids selected from ethylhexanoic acid and 3,5,5-trimethylhexanoic acid; pentaerythritol, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargon Acid, capric acid, oleic acid, isopentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethyl Hexanoic acid, 3,5,5 tetraester of one or two or more fatty acids selected from the trimethylhexanoic acid.

Note that the ester with two or more fatty acids may be a mixture of two or more esters of one type of fatty acid and polyol. An ester of two or more types of mixed fatty acid and polyol, particularly an ester of mixed fatty acid and polyol, Excellent low temperature characteristics and compatibility with refrigerants.
The base oil has an ASTM color of 1 or less, an interfacial tension of 20 mN / m or more, an extraction water pH of 5.5 or more, an ash content of 0.1% by mass or less, and a volume resistance of 10 ⁹ Ωm or more. It is preferable. Base oils having such properties are suitable because of their good stability and excellent electrical insulation.

  In producing the polyol ester-based compound, coloring can be suppressed by performing an esterification reaction in an inert gas atmosphere. If the amount of the aliphatic monocarboxylic acid is less than the stoichiometric amount in the ratio of the polyhydric alcohol to be reacted and the aliphatic monocarboxylic acid, the hydroxyl group remains and the hydroxyl value increases, When the amount is larger than the stoichiometric amount, the carboxylic acid remains, the acid value increases, and the pH of the extracted water decreases. Therefore, it is desirable to optimize the molar ratio of the polyhydric alcohol to the aliphatic monocarboxylic acid, and it is desirable to carry out a treatment to reduce the amount of the remaining esterification catalyst (ash content) as much as possible.

The refrigerating machine oil composition of the present invention includes, as a base oil, the aforementioned polyoxyalkylene glycols, polyvinyl ethers, poly (oxy) alkylene glycols or copolymers of monoethers and polyvinyl ethers, and polyol esters. A base oil comprising at least one oxygen-containing compound selected from the group consisting of:
Among these, polyvinyl ethers are particularly preferably used because they are excellent in compatibility with the refrigerant and volume resistivity.

In the present invention, the base oil has a kinematic viscosity at 100 ° C. of preferably 1 mm ² / s to 50 mm ² / s, more preferably 3 mm ² / s to 40 mm ² / s, and even more preferably 4 mm ² / s. s to 30 mm ² / s. When the kinematic viscosity is 1 mm ² / s or more, good lubricating performance (load resistance) is exhibited, and the sealing property is good, and when it is 50 mm ² / s or less, the energy saving property is also good.
The number average molecular weight of the base oil is preferably 300 or more and 3000 or less, more preferably 500 or more and 3000 or less, and further preferably 700 or more and 2500 or less. The flash point of the base oil is preferably 150 ° C. or higher. If the number average molecular weight of the base oil is 300 or more and 3000 or less, the desired performance as a refrigerating machine oil can be exhibited, and the flash point of the base oil. Can be within the above range.

Further, the viscosity index of the base oil in the present invention is preferably 60 or more, and more preferably 80 or more. However, the upper limit of the viscosity index is about 300 due to manufacturing restrictions.
When the viscosity index is 60 or more, a decrease in kinematic viscosity at high temperatures can be suppressed.
The viscosity index of the base oil is measured in accordance with JIS K 2283.

<Refrigerant>
As a refrigerant to which the lubricating oil composition for a compression refrigerator of the present invention is applied, a refrigerant containing a saturated fluorocarbon compound (HFC) having 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms is used. .
Examples of the saturated fluorinated hydrocarbon compound having 1 to 3 carbon atoms include trifluoromethane, difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1 , 1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2,2-pentafluoroethane, 1,1,1,3,3-pentafluoropropane Is preferred.
These refrigerants may be used alone or in combination of two or more.
For example, when difluoromethane (R32) is used as the saturated fluorinated hydrocarbon compound, R32 is preferably used alone, but R32 and 1,1,1,2,2-pentafluoroethane (R125) are mixed. Alternatively, R32, R125, and 1,1,1,2-tetrafluoroethane (R134a) may be mixed. A typical example of the former is R410A, and a typical example of the latter is R407C.
When a mixture of R32 and other saturated fluorinated hydrocarbon compounds having 1 to 3 carbon atoms is used, the ratio of R32 in the whole refrigerant is preferably 20% by mass or more, and 40% by mass or more. Is more preferable, and 70% by mass or more is more preferable.

Furthermore, you may mix and use the said C1-C3 saturated fluorinated hydrocarbon compound with refrigerant | coolants other than a C1-C3 saturated fluorinated hydrocarbon compound. In this case, the mixing ratio of the refrigerant other than the saturated fluorinated hydrocarbon compound having 1 to 3 carbon atoms is preferably 30% by mass or less, and more preferably 20% by mass or less based on the whole refrigerant.
The refrigerant other than the saturated fluorinated hydrocarbon compound having 1 to 3 carbon atoms is selected from carbon dioxide (CO ₂ ), low boiling point hydrocarbon (HC), ammonia, or a compound represented by the following molecular formula (A). There may be mentioned at least one fluorine-containing organic compound.
_{C p O q F r R s} ··· (A)
(In the formula, R represents Cl, Br, I or H, p is 1 to 6, q is 0 to 2, r is 1 to 14, and s is an integer of 0 to 13. However, q is 0. In the case of p, p is 2 to 6, and the molecule has one or more carbon-carbon unsaturated bonds.)

Hereinafter, the refrigerant represented by the molecular formula (A) will be described in detail.
The molecular formula (A) represents the type and number of elements in the molecule, and the formula (A) represents a fluorine-containing organic compound having 1 to 6 carbon atoms C. If it is a fluorine-containing organic compound having 1 to 6 carbon atoms, it can have physical and chemical properties such as boiling point, freezing point, and latent heat of vaporization required as a refrigerant.
In the molecular formula (A), the bond form of p carbon atoms represented by C _p includes a carbon-carbon single bond, an unsaturated bond such as a carbon-carbon double bond, a carbon-oxygen double bond, and the like. It is. The carbon-carbon unsaturated bond is preferably a carbon-carbon double bond from the viewpoint of stability, and the number thereof is one or more, but one is preferable.

In addition, in the molecular formula (A), the bonding form of q oxygen atoms represented by O _q is preferably oxygen derived from an ether group, a hydroxyl group, or a carbonyl group. The number q of oxygen atoms may be 2 and includes the case of having two ether groups or hydroxyl groups.
When _q in Oq is 0 and no oxygen atom is contained in the molecule, p is 2 to 6, and the molecule has one or more unsaturated bonds such as a carbon-carbon double bond. That is, at least one of the bonding forms of p carbon atoms represented by C _p needs to be a carbon-carbon unsaturated bond.
In the molecular formula (A), R represents Cl, Br, I, or H, and any of these may be used. However, since there is little risk of destroying the ozone layer, R may be H. preferable.
As described above, preferred examples of the fluorine-containing organic compound represented by the molecular formula (A) include unsaturated fluorinated hydrocarbon compounds, fluorinated ether compounds, fluorinated alcohol compounds, and fluorinated ketone compounds.
Hereinafter, these compounds will be described.

[Unsaturated fluorinated hydrocarbon compound]
In the present invention, as an unsaturated fluorinated hydrocarbon compound used as a refrigerant for a refrigerator, for example, in the molecular formula (A), R is H, p is 2 to 6, q is 0, and r is 1 to 12. , S is an unsaturated fluorinated hydrocarbon compound having 0-11.
Preferable examples of such unsaturated fluorinated hydrocarbon compounds include fluorinated products of linear or branched chain olefins having 2 to 6 carbon atoms and cyclic olefins having 4 to 6 carbon atoms.
Specifically, ethylene introduced with 1 to 3 fluorine atoms, propene introduced with 1 to 5 fluorine atoms, butenes introduced with 1 to 7 fluorine atoms, 1 to 9 Pentenes introduced with fluorine atoms, hexenes introduced with 1 to 11 fluorine atoms, cyclobutene introduced with 1 to 5 fluorine atoms, cyclopentene introduced with 1 to 7 fluorine atoms, 1 And cyclohexene into which 9 fluorine atoms are introduced.

Among these unsaturated fluorinated hydrocarbon compounds, unsaturated fluorinated hydrocarbon compounds having 2 to 3 carbon atoms are preferable, and examples thereof include fluorides of ethylene such as trifluoroethylene and fluorides of various propenes. The fluoride is more preferable. Examples of the propene fluoride include 3,3,3-trifluoropropene, 1,3,3,3-tetrafluoropropene, and 2,3,3,3-tetrafluoropropene. In particular, 1,2,3,3,3-pentafluoropropene (HFO1225ye), 1,3,3,3-tetrafluoropropene (HFO1234ze) and 2,3,3,3-tetrafluoropropene (HFO1234yf) It is suitable in that it has a low global warming potential.
In the present invention, this unsaturated fluorinated hydrocarbon compound may be used alone or in combination of two or more.

[Fluorinated ether compound]
In the present invention, examples of the fluorinated ether compound used as the refrigerant of the refrigerator include, in the molecular formula (A), R is H, p is 2 to 6, q is 1 to 2, r is 1 to 14, Examples include fluorinated ether compounds in which s is 0 to 13.
As such a fluorinated ether compound, for example, a fluorinated product of a chain aliphatic ether having 2 to 6 carbon atoms, having 1 to 2 ether bonds, and having an alkyl group being linear or branched Further, there can be mentioned a fluorinated product of a cyclic aliphatic ether having 3 to 6 carbon atoms and having 1 to 2 ether bonds.
Specifically, fluorinated dimethyl ether introduced with 1 to 6 fluorine atoms, fluorinated methyl ethyl ether introduced with 1 to 8 fluorine atoms, and fluorinated with 1 to 8 fluorine atoms introduced Dimethoxymethane, fluorinated methyl propyl ethers introduced with 1 to 10 fluorine atoms, fluorinated methyl butyl ethers introduced with 1 to 12 fluorine atoms, fluorinated methyl propyl ethers introduced with 1 to 12 fluorine atoms Ethyl propyl ethers, oxetane fluoride introduced with 1-6 fluorine atoms, 1,3-dioxolane fluoride introduced with 1-6 fluorine atoms, 1-8 fluorine atoms introduced And fluorinated tetrahydrofuran.

Examples of these fluorinated ether compounds include hexafluorodimethyl ether, pentafluorodimethyl ether, bis (difluoromethyl) ether, fluoromethyl trifluoromethyl ether, trifluoromethyl methyl ether, perfluorodimethoxymethane, 1-trifluoromethoxy-1, 1,2,2-tetrafluoroethane, difluoromethoxypentafluoroethane, 1-trifluoromethoxy-1,2,2,2-tetrafluoroethane, 1-difluoromethoxy-1,1,2,2-tetrafluoroethane 1-difluoromethoxy-1,2,2,2-tetrafluoroethane, 1-trifluoromethoxy-2,2,2-trifluoroethane, 1-difluoromethoxy-2,2,2-trifluoroethane, perfluoro Kisetan, perfluoro-1,3-dioxolane, various isomers of pentafluoropropane oxetane, and the like tetrafluorooxetane of various isomers.
In the present invention, this fluorinated ether compound may be used alone or in combination of two or more.

[Fluoroalcohol compound]
In the present invention, examples of the fluorinated alcohol compound used as the refrigerant of the refrigerator include, in the molecular formula (A), R is H, p is 1 to 6, q is 1 to 2, r is 1 to 13, Examples thereof include fluorinated ether compounds in which s is 1 to 13.
Preferred examples of such a fluorinated alcohol compound include a fluorinated product of a linear or branched aliphatic alcohol having 1 to 6 carbon atoms and having 1 to 2 hydroxyl groups.
Specifically, fluorinated methyl alcohol introduced with 1 to 3 fluorine atoms, fluorinated ethyl alcohol introduced with 1 to 5 fluorine atoms, and fluorinated with 1 to 7 fluorine atoms introduced Propyl alcohols, fluorinated butyl alcohols introduced with 1 to 9 fluorine atoms, fluorinated pentyl alcohols introduced with 1 to 11 fluorine atoms, and fluorines with 1 to 4 fluorine atoms introduced And ethylene glycol and fluorinated propylene glycol into which 1 to 6 fluorine atoms are introduced.

Examples of these fluorinated alcohol compounds include monofluoromethyl alcohol, difluoromethyl alcohol, trifluoromethyl alcohol, various isomers of difluoroethyl alcohol, various isomers of trifluoroethyl alcohol, various isomers of tetrafluoroethyl alcohol, Various isomers of pentafluoroethyl alcohol and difluoropropyl alcohol, various isomers of trifluoropropyl alcohol, various isomers of tetrafluoropropyl alcohol, various isomers of pentafluoropropyl alcohol, various isomers of hexafluoropropyl alcohol, hepta Fluoropropyl alcohol, difluorobutyl alcohol isomers, trifluorobutyl alcohol isomers, tetrafluorobutyl alcohol Fluorinated alcohols such as isomers, various isomers of pentafluorobutyl alcohol, various isomers of hexafluorobutyl alcohol, various isomers of heptafluorobutyl alcohol, various isomers of octafluorobutyl alcohol; nonafluorobutyl alcohol, difluoro Various isomers of ethylene glycol, trifluoroethylene glycol, tetrafluoroethylene glycol, various isomers of difluoropropylene glycol, various isomers of trifluoropropylene glycol, various isomers of tetrafluoropropylene glycol, pentafluoropropylene glycol Various isomers, fluorinated propylene glycols such as hexafluoropropylene glycol; and fluorinated trimethyle corresponding to the fluorinated propylene glycol Glycol and the like.
In the present invention, these fluorinated alcohol compounds may be used alone or in combination of two or more.

[Fluorinated ketone compounds]
In the present invention, for example, in the molecular formula (A), R is H, p is 2 to 6, q is 1 to 2, r is 1 to 12, A fluorinated ketone compound in which s is 0 to 11 can be mentioned.
Preferable examples of such a fluorinated ketone compound include fluorinated products of aliphatic ketones having 3 to 6 carbon atoms and linear or branched alkyl groups.
Specifically, fluorinated acetone introduced with 1 to 6 fluorine atoms, fluorinated methyl ethyl ketone introduced with 1 to 8 fluorine atoms, and fluorinated diethyl ketone introduced with 1 to 10 fluorine atoms Examples thereof include fluorinated methyl propyl ketones into which 1 to 10 fluorine atoms are introduced.

Examples of these fluorinated ketone compounds include hexafluorodimethyl ketone, pentafluorodimethyl ketone, bis (difluoromethyl) ketone, fluoromethyl trifluoromethyl ketone, trifluoromethyl methyl ketone, perfluoromethyl ethyl ketone, and trifluoromethyl-1,1. , 2,2-tetrafluoroethyl ketone, difluoromethyl pentafluoroethyl ketone, trifluoromethyl-1,1,2,2-tetrafluoroethyl ketone, difluoromethyl-1,1,2,2-tetrafluoroethyl ketone, Examples include difluoromethyl-1,2,2,2-tetrafluoroethyl ketone, trifluoromethyl-2,2,2-trifluoroethyl ketone, and difluoromethyl-2,2,2-trifluoroethyl ketone.
In the present invention, these fluorinated ketone compounds may be used alone or in combination of two or more.

[Other additives]
The refrigerating machine oil composition of the present invention preferably contains an antioxidant or an acid scavenger. Furthermore, at least one additive selected from among extreme pressure agents, oily agents, metal deactivators and antifoaming agents can be contained.
(Antioxidant)
Antioxidants include 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,2′-methylenebis (4-methyl-6-tert). -Butylphenol) and the like, phenyl-α-naphthylamine, N.I. It is preferable to incorporate an amine-based antioxidant such as N′-di-phenyl-p-phenylenediamine. The antioxidant is preferably contained in the composition in an amount of 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, from the viewpoints of effects and economy.

(Acid scavenger)
Examples of the acid scavenger include epoxy compounds such as glycidyl ester, phenyl glycidyl ether, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, and epoxidized soybean oil. In particular, at least one selected from glycidyl ester, glycidyl ether and α-olefin oxide is preferably used.
As the glycidyl ether, a linear, branched, cyclic saturated or unsaturated aliphatic mono- or polyhydric alcohol having 3 to 30, preferably 4 to 24, more preferably 6 to 16 carbon atoms, or Examples thereof include glycidyl ether derived from an aromatic compound containing one or more hydroxyl groups. In the case of an aliphatic polyhydric alcohol or an aromatic compound containing two or more hydroxyl groups, all of the hydroxyl groups must be glycidyl etherified from the viewpoint of suppressing an increase in the hydroxyl value for the stability of the lubricating oil composition. preferable.

Among these, glycidyl ether derived from a linear, branched or cyclic saturated aliphatic monoalcohol having 6 to 16 carbon atoms is particularly preferable. Examples of such glycidyl ether include 2-ethylethyl glycidyl ether, isononyl glycidyl ether, caprinoyl glycidyl ether, lauryl glycidyl ether, and myristyl glycidyl ether.
Specific examples of the glycidyl ester include phenyl glycidyl ester, alkyl glycidyl ester, alkenyl glycidyl ester, etc., and preferable examples include glycidyl-2,2-dimethyloctanoate, glycidyl benzoate, glycidyl acrylate, glycidyl methacrylate. Etc. can be exemplified.

On the other hand, the α-olefin oxide generally has 4 to 50 carbon atoms, preferably 4 to 24 carbon atoms, more preferably 6 to 16 carbon atoms.
In this invention, the said acid scavenger may use 1 type and may be used in combination of 2 or more type. Moreover, the compounding quantity is 0.005-10 mass% normally based on the composition whole quantity from the point of an effect and suppression of sludge generation, Especially the range of 0.05-6 mass% is preferable.

(Extreme pressure agent)
Examples of extreme pressure agents include phosphorous extreme pressure agents such as phosphate esters, acid phosphate esters, phosphite esters, acid phosphite esters, and amine salts thereof.
Among these phosphorous extreme pressure agents, tricresyl phosphate, trithiophenyl phosphate, tri (nonylphenyl) phosphite, dioleyl hydrogen phosphite, 2-ethylhexyl diphenyl phosphite in terms of extreme pressure and friction characteristics Etc. are particularly preferred.

Moreover, as an extreme pressure agent, the metal salt of carboxylic acid is mentioned. The metal salt of a carboxylic acid here is preferably a carboxylic acid having 3 to 60 carbon atoms, further a metal salt of a fatty acid having 3 to 30 carbon atoms, particularly preferably 12 to 30 carbon atoms. Moreover, the metal salt of the dimer acid and trimer acid of the said fatty acid, and C3-C30 dicarboxylic acid can be mentioned. Among these, a metal salt of a fatty acid having 12 to 30 carbon atoms and a dicarboxylic acid having 3 to 30 carbon atoms is particularly preferable.
On the other hand, as the metal constituting the metal salt, an alkali metal or an alkaline earth metal is preferable, and an alkali metal is particularly optimal.
In addition, as extreme pressure agents, as extreme pressure agents other than those described above, for example, sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiocarbamates, thioterpenes, dialkylthiodipropionates, etc. The sulfur type extreme pressure agent can be mentioned.
The blending amount of the extreme pressure agent is preferably 0.001 to 5 mass%, more preferably 0.005 to 3 mass%, based on the total amount of the composition, from the viewpoint of lubricity and stability. One of these extreme pressure agents may be used alone, or two or more thereof may be used in combination.

(Oil-based agent)
Examples of oil-based agents include aliphatic saturated and unsaturated monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, lauryl Aliphatic saturated and unsaturated monoalcohols such as alcohol, oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine and oleylamine, aliphatic saturated and unsaturated monocarboxylic amides such as lauric acid amide and oleic acid amide, glycerin And partial esters of polyhydric alcohols such as sorbitol and aliphatic saturated or unsaturated monocarboxylic acids.
These may be used individually by 1 type and may be used in combination of 2 or more type. Further, the blending amount is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total amount of the composition.

(Metal deactivator, antifoaming agent)
Examples of the metal deactivator include copper deactivators such as N- [N, N′-dialkyl (C3-C12 alkyl group) aminomethyl] triazole, and the like. Examples of the agent include silicone oil and fluorinated silicone oil.

[Refrigerator lubrication method using lubricating oil composition for compression refrigerators]
The lubricating oil composition for a compression type refrigerator of the present invention is suitable for a refrigerator using a refrigerant containing the saturated fluorinated hydrocarbon having 1 to 3 carbon atoms.
In the refrigerator lubricating method using the lubricating oil composition for a refrigerator according to the present invention, the amount of the various refrigerants and the lubricating oil composition for the refrigerator is the mass ratio of the refrigerant / the lubricating oil composition for the refrigerator. It is preferable to be in the range of 99/1 to 10/90, more preferably 95/5 to 30/70. When the amount of the refrigerant is less than the above range, the refrigerating capacity is lowered, and when it is more than the above range, the lubricating performance is lowered, which is not preferable. The lubricating oil composition for a refrigerator of the present invention can be used for various refrigerators, and can be preferably applied particularly to a compression refrigeration cycle of a compression refrigerator.

[refrigerator]
The refrigerator to which the lubricating oil composition for a refrigerator of the present invention is applied includes a compressor, a condenser, an expansion mechanism (an expansion valve, etc.) and an evaporator, or a compressor, a condenser, an expansion mechanism, a dryer and an evaporator. The above-described lubricating oil composition for a refrigerator according to the present invention is used as a refrigerator oil, and the above-described various refrigerants are used as a refrigerant.
Here, the dryer is preferably filled with a desiccant made of zeolite having a pore diameter of 0.33 nm or less. Examples of the zeolite include natural zeolite and synthetic zeolite. Further, it is more preferable that the zeolite has a CO ₂ gas absorption capacity of 1% or less at 25 ° C. and a CO ₂ gas partial pressure of 33 kPa. Examples of such synthetic zeolite include trade names XH-9 and XH-600 manufactured by Union Showa Co., Ltd.
In the present invention, when such a desiccant is used, moisture can be efficiently removed without absorbing the refrigerant in the refrigeration cycle, and at the same time, pulverization due to deterioration of the desiccant itself is suppressed, and thus is caused by pulverization. There is no risk of abnormal wear or the like due to blockage of piping or entry into the compressor sliding portion, and the refrigerator can be stably operated for a long time.

In a refrigerator to which the lubricating oil composition for a refrigerator of the present invention is applied, there are various sliding portions (for example, bearings) in the compressor. In the present invention, the sliding portion is made of an engineering plastic, or has an organic coating film or an inorganic coating film, particularly from the viewpoint of sealability.
Preferred examples of the engineering plastic include polyamide resin, polyphenylene sulfide resin, polyacetal resin, and the like in terms of sealing properties, slidability, wear resistance, and the like.
In addition, as an organic coating film, for example, fluorine-containing resin coating film (polytetrafluoroethylene coating film, etc.), polyimide coating film, polyamideimide coating film, And a thermosetting insulating film formed using a resin base material composed of a polyhydroxy ether resin and a polysulfone-based resin and a resin coating containing a crosslinking agent.
On the other hand, examples of the inorganic coating film include a graphite film, a diamond-like carbon film, a nickel film, a molybdenum film, a tin film, and a chromium film in terms of sealing properties, slidability, and wear resistance. This inorganic coating film may be formed by plating, or may be formed by a PVD method (physical vapor deposition method).
As the sliding portion, a conventional alloy system such as an Fe-based alloy, an Al-based alloy, a Cu-based alloy, or the like can also be used.

[System using refrigeration oil composition]
The lubricating oil composition for a compression refrigerator of the present invention can be used for, for example, a car air conditioner, an electric car air conditioner, a gas heat pump, an air conditioner, a refrigerator, a vending machine, a showcase, various hot water supply systems, a refrigeration / heating system, and the like. it can.
In the present invention, the water content in the system is preferably 300 ppm by mass or less, and more preferably 200 ppm by mass or less. The residual air partial pressure in the system is preferably 10 kPa or less, more preferably 5 kPa or less.
The lubricating oil composition for a compression-type refrigerator of the present invention contains a specific oxygen-containing compound as a base oil as a main component, has a low viscosity and can improve energy saving, and has a sealing property. Is excellent.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The properties of the base oil and various characteristics of the lubricating oil composition for refrigerators were determined according to the following procedures.

<Properties of base oil>
(1) 100 ° C. Kinematic viscosity Measured according to JIS K2283-1983 using a glass capillary viscometer.
(2) Number average molecular weight The number average molecular weight was measured using gel permeation chromatography (GPC). GPC was measured using an IR detector using HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation) and THF (tetrahydrofuran) as an eluent. From the results, the number average molecular weight was determined from a calibration curve using a polystyrene standard sample.
(3) Flash point Measured according to JIS K 2265 (COC method).

<Thermal stability test of lubricating oil composition for refrigerators>
An autoclave with an internal volume of 200 mL is filled with oil / refrigerant (ratio of 30 g / 30 g, moisture content in oil: 500 mass ppm) and a metal catalyst composed of iron, copper, and aluminum, and sealed with an air pressure of 0.7 kPa. After maintaining for 720 hours at a temperature of 200 ° C., the oil appearance, precipitates, and alteration of the catalyst were visually observed, and the acid value was measured. The acid value was measured by an indicator method according to “Lubricating oil neutralization test method” defined in JIS K 2501.
<Measurement of two-layer separation temperature>
A predetermined amount of a sample was added to a pressure-resistant glass ampoule so as to be 10% by weight with respect to Freon 32 difluoromethane (Freon 32), and this was connected to a vacuum pipe and a Freon 32 gas pipe. The ampoule was vacuum deaerated at room temperature, cooled with liquid nitrogen, and a predetermined amount of Freon 32 was collected. Subsequently, the ampule was sealed, and the low temperature separation temperature was gradually cooled from room temperature in a thermostat, while the high temperature separation temperature was measured by gradually heating from room temperature to + 40 ° C. to start phase separation.
<Volume resistivity>
After drying at 100 ° C. for 1 hour under reduced pressure (0.3 to 0.8 mmHg), room temperature sample oil was sealed in a liquid cell for measuring volume resistivity. The volume resistivity was measured at an applied voltage of 250 V using an R8340 digital ultrahigh resistance / microammeter manufactured by Advantest Corporation.

<Blending ingredients>
The kind of each component used for preparation of the lubricating oil composition for refrigerators is shown below.
(1) Base oil / PVE-A1 to PVE-A7: Polyethyl vinyl ether / PVE-B1 to PVE-B2: Polyethyl vinyl ether (PEVE) / polyisobutyl vinyl ether copolymer (PIBVE / PIBVE (molar ratio) 9/1) ]]
PVE-C1 to PVE-C2: polyethyl vinyl ether (PEVE) / polyisobutyl vinyl ether copolymer (PIBVE / PIBVE (molar ratio) 8/2)]
PAG-1 to PAG-2: Polyoxypropylene glycol ECP-1 to ECP-2: Polypropylene glycol (PPG) / polyethyl vinyl ether (PEV) copolymer (PPG / PEV molar ratio 5/5)
POE-1 to POE-2: pentaerythritol octanoic acid (C8 acid) nonanoic acid (C9 acid) ester (C8 acid / C9 acid molar ratio 1 / 1.1)
Table 1 shows the properties of these base oils.

(2) Antioxidant:
2,6-di-tert-butyl-4-methylphenol (0.3% by mass)
(3) Acid scavenger:
2-Ethylhexyl glycidyl ether (0.3% by mass)
(4) Other additives The following components were used, and the total amount of the composition was added so that the amount (mass%) shown in () was 1.1 mass% as a whole.
Extreme pressure agent: tricresyl phosphate (1.0% by mass)
-Antifoaming agent: Silicone-based antifoaming agent (0.1% by mass)

<Examples 1-8 and Comparative Examples 1-9>
A refrigerating machine oil composition having the composition shown in Table 2 was prepared using the base oil shown in Table 2, and the mass ratio of R32 (difluoromethane) or R410A [R32 and R125 (pentafluoroethane) as a refrigerant was 50: 50 mixture] was used to evaluate the thermal stability properties of the composition. The results are shown in Table 2.

From Table 2, it can be seen that:
In Examples 1 to 8 where the lubricating oil composition for a compression type refrigerator of the present invention was used in a system using R32 (difluoromethane) as a refrigerant, the oil appearance was good in both heat and oxidation stability tests. Yes, no precipitates, no discoloration of the catalyst, and low acid value. Moreover, the volume low efficiency is also high.
On the other hand, Comparative Examples 1 to 9 use a base oil with a large amount of water, so that not only the acid value is high, but the oil appearance is yellow, pale yellow or brown, and there are precipitates. The alteration is also remarkable. Further, the volumetric efficiency is low, which is not preferable.

  The lubricating oil composition for a compression-type refrigerator of the present invention has a low global warming potential, and in particular, a refrigerant that uses a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, which is a refrigerant that can be used for air conditioners, car air conditioners, and the like It is used for compression type refrigerators that use and exhibits excellent thermal and oxidation stability.

< Reference Examples 1-7, Example 8 and Comparative Examples 1-9>
A refrigerating machine oil composition having the composition shown in Table 2 was prepared using the base oil shown in Table 2, and the mass ratio of R32 (difluoromethane) or R410A [R32 and R125 (pentafluoroethane) as a refrigerant was 50: 50 mixture] was used to evaluate the thermal stability properties of the composition. The results are shown in Table 2.

From Table 2, it can be seen that:
In Example 8 in which the lubricating oil composition for a compression refrigerator of the present invention was used in a system using R32 (difluoromethane) as a refrigerant, the oil appearance was good in the heat and oxidation stability test, and the precipitate There is no discoloration of the catalyst, and the acid value is low. Moreover, the volume low efficiency is also high.
On the other hand, Comparative Examples 1 to 9 use a base oil with a large amount of water, so that not only the acid value is high, but the oil appearance is yellow, pale yellow or brown, and there are precipitates. The alteration is also remarkable. Further, the volumetric efficiency is low, which is not preferable.

Claims (15)

  All are selected from polyoxyalkylene glycols, polyvinyl ethers, poly (oxy) alkylene glycols or their monoether and polyvinyl ether copolymers, and polyol esters having a water content of 500 ppm by mass or less. A lubricating oil composition for a compression-type refrigerator using a refrigerant containing a saturated fluorinated hydrocarbon having 1 to 3 carbon atoms, using at least one oxygen-containing organic compound as a base oil. The oxygen-containing organic compound is represented by the following general formula (II)

(In the formula, R ⁴ , R ⁵ and R ⁶ each represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same or different, and R ⁷ has 2 carbon atoms. 10 is a divalent hydrocarbon group, R ⁸ is a hydrocarbon group having 1 to 10 carbon atoms, p is an average value of 0 to 10 and R ^{4 to} R ⁸ are the same for each structural unit. and or different respectively, and a plurality of R ^{7 O} in the case of R ^{7 O} there are a plurality may be the same or different.)
The lubricating oil composition for a compression type refrigerating machine according to claim 1, wherein the main component is a polyvinyl compound having a structural unit represented by formula (1).   The lubricating oil composition for a compression type refrigerator according to claim 1 or 2, comprising an antioxidant and / or an acid scavenger.   The lubricating oil composition for a compression type refrigerator according to any one of claims 1 to 3, wherein the saturated fluorinated hydrocarbon having 1 to 3 carbon atoms is difluoromethane (R32).   The refrigerant is a mixture of difluoromethane (R32) and pentafluoroethane (R125), or difluoromethane (R32), pentafluoroethane (R125), 1,1,1,2 tetrafluoroethane (R134a). The lubricating oil composition for a compression type refrigerator according to any one of claims 1 to 4, wherein the lubricating oil composition is a mixture of   The lubricating oil composition for a compression type refrigerator according to any one of claims 1 to 5, wherein the refrigerant is a refrigerant containing 70 mass% or more of difluoromethane (R32). The lubricating oil composition for a compression type refrigerating machine according to any one of claims 1 to 6, wherein the base oil has a kinematic viscosity at 100 ° C of 1 mm ² / s to 50 mm ² / s.   The lubricating oil composition for a compression type refrigerator according to any one of claims 1 to 7, wherein the base oil has a number average molecular weight of 300 or more and 3000 or less.   The lubricating oil composition for a compression type refrigerating machine according to any one of claims 1 to 8, wherein the base oil has a viscosity index of 60 or more.   Furthermore, the lubricating oil for compression type refrigerators of any one of Claims 1-9 containing the at least 1 sort (s) of additive chosen from an extreme pressure agent, an oiliness agent, a metal deactivator, and an antifoamer. Composition.   The lubricating oil composition for a compression type refrigerator according to any one of claims 1 to 10, wherein the sliding portion of the compression refrigerator is made of an engineering plastic, or has an organic coating film or an inorganic coating film. .   The organic coating film is formed by using a polytetrafluoroethylene coating film, a polyimide coating film, a polyamideimide coating film, a resin base material composed of a polyhydroxy ether resin and a polysulfone resin, and a resin paint containing a crosslinking agent. The lubricating oil composition for a compression type refrigerator according to claim 11, wherein the lubricating oil composition is any one of a curable insulating film.   The lubricating oil composition for a compression type refrigerator according to claim 11, wherein the inorganic coating film is any one of a graphite film, a diamond-like carbon film, a tin film, a chromium film, a nickel film, and a molybdenum film.   The compression refrigerator according to any one of claims 1 to 13, which is used in a car air conditioner, an electric car air conditioner, a gas heat pump, an air conditioner, a refrigerator, a vending machine, a showcase, a hot water supply system, or a refrigeration / heating system. Lubricating oil composition.   The lubricating oil composition for a compression refrigeration machine according to claim 14, wherein the water content in the system is 300 ppm by mass or less and the residual air partial pressure is 10 kPa or less.