WO2017222004A1

WO2017222004A1 - Refrigerating machine oil and composition for refrigerating machines

Info

Publication number: WO2017222004A1
Application number: PCT/JP2017/022949
Authority: WO
Inventors: 中島　聡; 知也松本
Original assignee: 出光興産株式会社
Priority date: 2016-06-22
Filing date: 2017-06-22
Publication date: 2017-12-28
Also published as: JP2017226761A

Abstract

This refrigerating machine oil is a refrigerating machine oil for refrigerants containing difluoromethane (R32), and contains: a polyvinyl ether compound (A) comprising a constituent unit (a1) that has a methoxyethyl group in a side chain; and at least one agent selected from the group consisting of antioxidants (B) and acid scavengers (C).

Description

Refrigerator oil and composition for refrigerator

The present invention relates to a refrigerator oil and a refrigerator composition containing a refrigerant and a refrigerator oil.

In general, a compression refrigerator includes at least a compressor, a condenser, an expansion mechanism (an expansion valve, etc.), an evaporator, and the like, and a sealed system is mixed with a mixture of refrigerant and refrigerating machine oil (hereinafter, “ It also has a structure in which the composition for the refrigerator is also circulated. As a refrigerant used in a compression refrigerator, HFC (hydrofluorocarbon) that does not destroy the ozone layer is widely used. As HFC, R134a and the like are often used, but in recent years, the use of difluoromethane (R32) having a lower global warming potential is being studied. Hereinafter, difluoromethane (R32) is also referred to as “R32 refrigerant”.
Conventionally, as refrigerating machine oil used for R32 refrigerants, additives such as antioxidants, acid scavengers, extreme pressure agents, etc. are blended with polyvinyl ether compounds such as polyethyl vinyl ether, copolymers of ethyl vinyl ether and isobutyl vinyl ether, etc. (For example, refer to Patent Documents 1 and 2).

JP 2013-14672 A JP 2013-14673 A

The R32 refrigerant has a compressor discharge temperature of 20 ° C. or higher compared to R134a or the like. Therefore, the refrigerating machine oil used for the R32 refrigerant is likely to increase in acid value due to decomposition at a high temperature. In order to suppress such an increase in acid value, refrigerating machine oils are required to have excellent high-temperature oxidation stability. Moreover, since the inside of a compressor becomes high temperature, the refrigerating machine oil also needs lubricity under high temperature.
Furthermore, the refrigeration oil is generally required to circulate in the system of the compression refrigeration machine without phase separation from the refrigerant. In a compression refrigerator, the inside of a compressor becomes high temperature and the inside of a cooler becomes low temperature. Therefore, the refrigerating machine oil is required to have a property compatible with the refrigerant from a high temperature to a low temperature.

However, since the refrigerating machine oils disclosed in Patent Documents 1 and 2 are not sufficiently compatible with the R32 refrigerant and tend to phase separate at about −5 ° C., it is necessary to further lower the phase separation temperature. Further, the refrigerating machine oils disclosed in Patent Documents 1 and 2 are not sufficiently lubricated at high temperatures, and further improvements in lubricity are required.
This invention is made | formed in view of the above situation, and the subject of this invention is excellent in oxidation stability and lubricity also under high temperature, and with the refrigerant | coolant containing R32 over a wide temperature range from high temperature to low temperature. It is to provide a refrigerating machine oil having good compatibility.

As a result of intensive studies, the present inventors have found that a refrigerating machine oil containing a polyvinyl ether-based compound having a methoxyethyl group and a specific additive can solve the above problems, and completed the present invention.
That is, the present invention provides the following [1] and [2].
[1] Refrigerating machine oil for refrigerant containing difluoromethane (R32),
A polyvinyl ether compound (A) containing a structural unit (a1) having a methoxyethyl group in the side chain, and at least one selected from the group consisting of an antioxidant (B) and an acid scavenger (C) Refrigerator oil.
[2] A refrigerating machine composition comprising the refrigerating machine oil according to the above [1] and a refrigerant.

The refrigerating machine oil of the present invention is excellent in oxidation stability and lubricity even at high temperatures and has good compatibility with a refrigerant containing R32 over a wide temperature range from high temperature to low temperature.

[Refrigerator oil]
The refrigerating machine oil according to one embodiment of the present invention is a refrigerating machine oil for refrigerant containing R32 refrigerant, and includes a polyvinyl ether compound (A) containing a structural unit (a1) having a methoxyethyl group in the side chain, and an oxidation product. A refrigerating machine oil comprising at least one selected from the group consisting of an inhibitor (B) and an acid scavenger (C).

[Polyvinyl ether compound (A)]
The polyvinyl ether compound (A) is a compound having a polyvinyl ether structure and includes a structural unit (a1) having a methoxyethyl group in the side chain. A polyvinyl ether type compound (A) comprises the base oil of refrigerating machine oil. The refrigerating machine oil contains the polyvinyl ether compound (A) as a base oil, so that it is excellent in compatibility with the R32 refrigerant even in a low temperature environment, and can suppress the phase separation between the refrigerating machine oil and the refrigerant. is there.

The content of the polyvinyl ether compound (A) is preferably 70 to 99.7% by mass, more preferably 75 to 99.3% by mass, and still more preferably 80 to 80%, based on the total amount (100% by mass) of the refrigerating machine oil. It is 98.4 mass%. Thus, it is possible to make the refrigerating machine oil excellent in compatibility with the R32 refrigerant by increasing the content of the polyvinyl ether compound (A).
In addition, a polyvinyl ether type compound (A) may be contained individually by 1 type in refrigerating machine oil, and may be contained in combination of 2 or more type.

The kinematic viscosity at 40 ° C. of the polyvinyl ether compound (A) is preferably 10 to 400 mm ² / s, more preferably 15 to 220 mm ² / s, and still more preferably 28 to 110 mm ² / s. By making the 40 degreeC kinematic viscosity of a compound (A) into these ranges, it becomes easy to make the lubricity of the refrigerating machine oil favorable under high temperature.
The viscosity index (VI) of the polyvinyl ether compound (A) is preferably 90 or more, more preferably 100 or more, and still more preferably 110 or more. When the polyvinyl ether compound (A) contains the structural unit (a1) having a methoxyethyl group in the side chain, the viscosity index tends to increase. Therefore, it becomes easy to improve the lubricity of the refrigerating machine oil, such that the kinematic viscosity becomes an appropriate value both at a low temperature and a high temperature, and the wear resistance of the refrigerating machine oil at a high temperature is improved.
In the present specification, the kinematic viscosity and the viscosity index mean values measured according to JIS K2283: 2000.

The number average molecular weight (Mn) of the polyvinyl ether compound (A) may be in the range where the kinematic viscosity at 40 ° C. falls within the above range, but from the viewpoint of improving the lubricating performance of the refrigerating machine oil, preferably 300 to 3000, More preferably, it is 350-2500, and still more preferably 400-2000.
In the present specification, the number average molecular weight is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and specifically means a value measured by the method described in Examples. To do.

<Structural unit (a1)>
The structural unit (a1) of the polyvinyl ether compound (A) is preferably one represented by the following general formula (1).

In the general formula (1), R ¹ to R ³ each independently represent a hydrogen atom or a carbon number of 1 to 8 (preferably 1 to 6, more preferably 1 to 4, more preferably 1 to 2). A hydrocarbon group is shown.

Examples of the hydrocarbon group that can be selected as R ¹ to R ³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups and other alkyl groups; cyclopentyl group, cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, various dimethylcyclohexyl groups and other cycloalkyl groups; phenyl group And aryl groups such as various methylphenyl groups, various ethylphenyl groups, and various dimethylphenyl groups; arylalkyl groups such as benzyl group, various phenylethyl groups, and various methylbenzyl groups;

Among these, all of R ¹ to R ³ are preferably either a hydrogen atom or an alkyl group, and more preferably all are hydrogen atoms. Note that R ¹ to R ³ in the general formula (1) may be the same or different for each structural unit. That is, the polyvinyl ether compound (A) can include copolymers in which any or all of R ¹ to R ³ are different for each structural unit.

It is preferable that a polyvinyl ether type compound (A) has another structural unit different from a structural unit (a1) with a structural unit (a1).
The content of the structural unit (a1) is all structural units (100 mol%) of the polyvinyl ether compound (A) from the viewpoint of compatibility with the R32 solvent and a refrigerating machine oil excellent in lubricity at high temperatures. On the basis, it is preferably 1 mol% or more, more preferably 10 mol% or more, still more preferably 20 mol% or more.
Further, the content of the structural unit (a1) is preferably 100 mol% or less, more preferably 70 mol% or less, and still more preferably 50 mol% or less, from the viewpoint of increasing the volume resistivity of the refrigerating machine oil.

<Structural unit (a2)>
The polyvinyl ether compound (A) preferably contains a structural unit (a2) represented by the following general formula (2), which is different from the structural unit (a1), together with the structural unit (a1). By setting it as the polyvinyl ether type compound (A) containing structural unit (a1) and (a2), the volume resistivity of refrigerating machine oil can be made high, for example.

In the above general formula (2), R ⁴ to R ⁶ are each independently a hydrogen atom or a carbon number of 1 to 8 (preferably 1 to 6, more preferably 1 to 4, more preferably 1 to 2). A hydrocarbon group is shown.
Examples of the hydrocarbon group that can be selected as R ⁴ to R ⁶ include the same hydrocarbon groups as those described above as R ¹ to R ³ . Among these, all of R ⁴ to R ⁶ are preferably either a hydrogen atom or an alkyl group, and more preferably all are hydrogen atoms.
R ⁷ represents a divalent hydrocarbon group having 2 to 10 carbon atoms (preferably 2 to 6, more preferably 2 to 4). R represents an integer of 0 to 10, preferably 0 to 3, more preferably 0 to 2, still more preferably 0 to 1, and still more preferably 0. When r is 2 or more, the plurality of R ⁷ may be the same or different from each other.

Examples of the divalent hydrocarbon group that can be selected as R ⁷ include an ethylene group, a phenylethylene group, a 1,2-propylene group, a 2-phenyl-1,2-propylene group, a 1,3-propylene group, and various types. Alkylene groups such as butylene group, various pentylene groups, various hexylene groups, various heptylene groups, various octylene groups, various nonylene groups, various decylene groups; cyclohexylene group, methylcyclohexylene group, ethylcyclohexylene group, dimethylcyclohexylene group, Divalent alicyclic hydrocarbon groups such as propylcyclohexylene group; divalent aromatic hydrocarbon groups such as various phenylene groups, various methylphenylene groups, various ethylphenylene groups, various dimethylphenylene groups and various naphthylene groups; toluene Alkyl groups and aromatics of alkyl aromatic hydrocarbons such as ethylbenzene A divalent alkyl aromatic hydrocarbon group having a monovalent bonding site in each moiety; a divalent alkyl aromatic hydrocarbon group having a bonding site in the alkyl group moiety of a polyalkyl aromatic hydrocarbon such as xylene and diethylbenzene; Etc.
Among these, as R ⁷ , an alkylene group is preferable, and an alkylene group having 2 to 4 carbon atoms is more preferable.

R ⁸ represents a hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 4).
The hydrocarbon group that can be selected as R ⁸ includes, for example, various nonyl groups and various decyl groups in addition to the groups exemplified as the hydrocarbon group having 1 to 8 carbon atoms that can be selected as R ¹ to R ³ described above. Alkyl groups such as: various propyl cyclohexyl groups, cycloalkyl groups such as various trimethyl cyclohexyl groups; aryl groups such as various propyl phenyl groups, various trimethyl phenyl groups, various butyl phenyl groups, various naphthyl groups; various phenyl propyl groups, various phenyls Arylalkyl groups such as butyl group; and the like.
Among these, as R ⁸ , an alkyl group is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable.

Note that since the structural unit (a2) has a structure different from that of the structural unit (a1), R ⁷ in the general formula (2) is an ethylene group (—CH ₂ CH ₂ —), and When R ⁸ is a methyl group, r is not 1.

The structural unit (a2) is more preferably a structural unit (a2-1) represented by the following general formula (2-1). By having the following structural unit (a2-1), the volume resistivity of the refrigerating machine oil can be increased, and the production of the polyvinyl ether compound (A) is facilitated.

(In the general formula (2-1), R ⁸ is the same as defined in the general formula (2).)

In one embodiment of the present invention, the content of the structural unit (a2-1) is preferably 70 based on the total amount (100 mol%) of the structural unit (a2) contained in the polyvinyl ether compound (A). To 100 mol%, more preferably 80 to 100 mol%, still more preferably 90 to 100 mol%.

In addition, the content of the structural unit in which R ⁸ in the general formulas (2) and (2-1) is an ethyl group is the total amount (100 mol%) of the structural unit (a2) contained in the polyvinyl ether compound (A). ), Preferably 50 to 100 mol%, more preferably 70 to 100 mol%, still more preferably 80 to 100 mol%, particularly preferably 100 mol%.
Further, when the polyvinyl ether compound (A) is the structural unit (a2-1) represented by the general formula (2-1), the structural unit (a1) represented by the general formula (1) is used. In particular, all of R ¹ to R ³ are preferably hydrogen atoms.
The content of the structural unit (a2) is preferably 0 to 99 mol%, more preferably 30 to 90 mol%, still more preferably 50, based on the total structural unit (100 mol%) of the polyvinyl ether compound (A). ~ 80 mol%.

Moreover, the polyvinyl ether compound (A) may have other structural units other than the structural unit (a1) and the structural unit (a2).
However, the total content of the structural unit (a1) and the structural unit (a2) is preferably 70 to 100 mol%, more preferably based on the total structural unit (100 mol%) of the polyvinyl ether compound (A). It is 80 to 100 mol%, more preferably 90 to 100 mol%, still more preferably 95 to 100 mol%, particularly preferably 100 mol%.

<Terminal part of polyvinyl ether compound (A)>
A monovalent group derived from a saturated hydrocarbon, ether, alcohol, ketone, amide, nitrile or the like may be introduced into the terminal portion of the polyvinyl ether compound (A).
In one embodiment of the present invention, at least one of the terminal portions of the polyvinyl ether compound (A) is preferably a group represented by the following general formula (3-1).

In the general formula (3-1), R ¹¹ to R ¹³ are each independently a hydrogen atom or 1 to 8 carbon atoms (preferably 1 to 6, more preferably 1 to 4, more preferably 1 to 2). Represents a hydrocarbon group.
R ¹⁴ represents a divalent hydrocarbon group having 2 to 10 carbon atoms (preferably 2 to 6, more preferably 2 to 4).
r1 represents an integer of 0 to 10, preferably 0 to 3, more preferably 0 to 2, and still more preferably 0 to 1. When r1 is 2 or more, the plurality of R ¹⁴ may be the same or different from each other.
R ¹⁵ represents a hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 4). * Represents a binding moiety.

Furthermore, in one embodiment of the present invention, one of the terminal portions of the polyvinyl ether compound (A) is a group represented by the general formula (3-1), and the other is the following general formula (3-1a), A group having any one of (3-1b) and (3-1c) or a group having an olefinically unsaturated bond is preferable, and a group of the following general formula (3-1a) is more preferable.

In the general formula (3-1a), R ^11a to R ^13a are each independently a hydrogen atom or 1 to 8 carbon atoms (preferably 1 to 6, more preferably 1 to 4, more preferably 1 to 2). Represents a hydrocarbon group.
R ^14a represents a divalent hydrocarbon group having 2 to 10 carbon atoms (preferably 2 to 6, more preferably 2 to 4).
r2 represents an integer of 0 to 10, preferably 0 to 3, more preferably 0 to 2, and still more preferably 0 to 1. When r2 is 2 or more, the plurality of R ^14a may be the same or different from each other.
R ^15a represents a hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 4). * Represents a binding moiety.

In the general formula (3-1b), R ^11b to R ^13b each independently represent a hydrogen atom or 1 to 8 carbon atoms (preferably 1 to 6, more preferably 1 to 4, more preferably 1 to 2). Represents a hydrocarbon group.
R ^14b and R ^16b each independently represent a divalent hydrocarbon group having 2 to 10 carbon atoms (preferably 2 to 6, more preferably 2 to 4).
r3 and r4 each independently represents an integer of 0 to 10, preferably 0 to 3, more preferably 0 to 2, and still more preferably 0 to 1. When r3 and r4 are 2 or more, the plurality of R ^14b and R ^16b may be the same or different from each other.
R ^15b and R ^17b each independently represent a hydrocarbon group having 1 to 10 carbon atoms (preferably 1 to 8, more preferably 1 to 6, and further preferably 1 to 4). * Represents a binding moiety.

In the general formula (3-1c), R ^11c to R ^13c each independently represents a hydrogen atom or 1 to 8 carbon atoms (preferably 1 to 6, more preferably 1 to 4, more preferably 1 to 2). Represents a hydrocarbon group.

In the above general formulas (3-1), (3-1a), (3-1b), and (3-1c), R ¹¹ to R ¹³ , R ^11a to R ^13a , R ^11b to R ^13b , And the hydrocarbon group having 1 to 8 carbon atoms that can be selected as R ^11c to R ^13c is the same as the hydrocarbon group having 1 to 8 carbon atoms that can be selected as R ⁴ to R ⁶ in the general formula (2). And suitable groups are the same.
The divalent hydrocarbon group having 2 to 10 carbon atoms that can be selected as R ¹⁴ , R ^14a , R ^14b , and R ^16b includes 2 carbon atoms that can be selected as R ⁷ in the general formula (2). The same as the divalent hydrocarbon group of ˜10 can be mentioned, and preferable groups are also the same.
Furthermore, as the hydrocarbon group having 1 to 10 carbon atoms that can be selected as R ¹⁵ , R ^15a , R ^15b , and R ^17b , the hydrocarbon group having 1 to 10 carbon atoms that can be selected as R ⁸ in the general formula (2). The same thing as a hydrocarbon group is mentioned, A suitable group is also the same.

<Synthesis Method of Polyvinyl Ether Compound (A)>
There is no restriction | limiting in particular as a synthesis method of a polyvinyl ether type compound (A), The raw material monomer which can form a structural unit (a1) and the raw material monomer which can form a structural unit (a2) as needed are used. And a method of synthesis by various polymerizations (radical polymerization, cationic polymerization, radiation polymerization, etc.).

As a raw material monomer which forms a structural unit (a1), the vinyl ether type monomer represented by the following general formula (I) is mentioned, for example.

(In the general formula (I), R ¹ to R ³ are the same as defined in the general formula (1).)

Moreover, as a raw material monomer which forms a structural unit (a2), the vinyl ether type monomer represented by the following general formula (II) is mentioned, for example.

(In the general formula (II), R ⁴ to R ⁸ and r are the same as defined in the general formula (2).)

From the viewpoint of obtaining a polyvinyl ether compound (A) having a desired kinematic viscosity, the synthesis method of the polyvinyl ether compound (A) is to add a raw material monomer into the system in the presence of a polymerization catalyst and a polymerization initiator, A method of allowing the polymerization reaction to proceed is preferred.

Examples of the polymerization catalyst include Bronsted acids, Lewis acids, and organometallic compounds, and Lewis acids are preferable.
Examples of Bronsted acids include hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, trichloroacetic acid, trifluoroacetic acid, and the like.
Examples of Lewis acids include boron trifluoride, aluminum trichloride, aluminum tribromide, tin tetrachloride, zinc dichloride, ferric chloride and the like, and boron trifluoride is preferable.
Examples of the organometallic compound include diethyl aluminum chloride, ethyl aluminum chloride, diethyl zinc and the like.

Examples of the polymerization initiator include water, alcohols, phenols, acetals, adducts of vinyl ethers and carboxylic acids, and these may be used alone or in combination of two or more. Depending on the type of these polymerization initiators, the terminal portion of the resulting polyvinyl ether compound (A) is formed.

Examples of alcohols include saturated fats having 1 to 20 carbon atoms such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, various pentanols, various hexanols, various heptanols, and various octanols. An unsaturated alcohol having 3 to 10 carbon atoms such as allyl alcohol; an ether-bonded oxygen-containing alcohol having 14 or less carbon atoms such as ethylene glycol monoalkyl ether and ethylene glycol monoaryl ether;
Examples of phenols include phenol and various cresols.
Examples of acetals include acetaldehyde dimethyl acetal, acetaldehyde diethyl acetal, acetaldehyde methyl ethyl acetal, acetaldehyde bis (methoxyethyl) acetal, and the like.
Examples of the adduct of vinyl ethers and carboxylic acid include adducts such as acetic acid, propionic acid, n-butyric acid, isobutyric acid, and 3,5,5-trimethylcaproic acid.

The polymerization initiation terminal of the obtained polyvinyl ether compound (A) is bonded with hydrogen when water, alcohols or phenols are used. When acetals are used, one alkoxy group eliminated from the acetals is bonded. When an adduct of vinyl ethers and carboxylic acid is used, an alkylcarbonyloxy group derived from the carboxylic acid moiety eliminated from the adduct of vinyl ethers and carboxylic acid is bonded.
On the other hand, the stop terminal of the polyvinyl ether compound (A) becomes an acetal, an olefin, or an aldehyde when water, alcohols, phenols, or acetals are used. In addition, in the case of an adduct of vinyl ethers and carboxylic acid, it becomes a carboxylic acid ester of hemiacetal, and becomes an aldehyde when hydrolyzed in the presence of an acid.

Although the polymerization reaction depends on the type of raw material monomer and polymerization initiator used, it is usually at a temperature of −80 to 150 ° C. (preferably 0 to 100 ° C.) and about 10 seconds to 10 hours after the reaction starts. It is preferable to end.
Moreover, the said polymerization reaction is normally performed in presence of a solvent. The solvent to be used is not particularly limited as long as it can dissolve the required amount of the reaction raw material and is inert to the polymerization reaction. For example, hydrocarbon solvents such as hexane, benzene and toluene; And ether solvents such as ether, 1,2-dimethoxyethane, tetrahydrofuran and the like.

When the polymer obtained after the polymerization reaction has an unsaturated bond, an acetal, and an aldehyde, it is preferable to further perform a hydrogenation treatment so that these become a saturated bond and an ether. The hydrogenation treatment is performed at a reaction temperature of 10 to 250 ° C. (preferably 50 to 200 ° C.) by introducing hydrogen gas at a hydrogen pressure of 0.1 to 10 MPa (preferably 1 to 6 MPa) in the presence of a hydrogenation catalyst. It is preferable.
Examples of the hydrogenation catalyst include metal catalysts such as nickel-based catalysts, platinum-based catalysts, palladium-based catalysts, and ruthenium-based catalysts. Catalysts in which these metal catalysts are supported on alumina or diatomaceous earth, Raney-type catalysts, and the like Can also be used.

[Base oils other than the polyvinyl ether compound (A)]
The refrigerating machine oil may contain only the polyvinyl ether compound (A) as the base oil, but may contain a base oil other than the polyvinyl ether compound (A) as long as the effects of the present invention are not impaired. Good.
Other base oils include, for example, polyvinyl ether compounds not containing the structural unit (a1), polyalkylene glycol compounds, poly (oxy) alkylene glycol or monoethers thereof, and polyvinyl ethers not containing the structural unit (a1) And a copolymer of polyol ester and the like.
These other base oils may be used alone or in combination of two or more.
These other base oils may be those having the same 40 ° C. kinematic viscosity as the polyvinyl ether compound (A), and the specific 40 ° C. kinematic viscosity is preferably 10 to 400 mm ² / s, more preferably. Is 15 to 220 mm ² / s, more preferably 28 to 110 mm ² / s.

In addition, the content of the base oil other than the polyvinyl ether compound (A) is based on 100 parts by mass of the polyvinyl ether compound (A) from the viewpoint of a refrigerating machine oil excellent in compatibility with the R32 refrigerant. The amount is preferably 0 to 30 parts by mass, more preferably 0 to 20 parts by mass, still more preferably 0 to 10 parts by mass, and still more preferably 0 to 3 parts by mass.

[Additive]
The refrigerating machine oil which concerns on one Embodiment of this invention contains an additive. The refrigerating machine oil contains an antioxidant (B), an acid scavenger (C), or both as an additive, but preferably contains both. Refrigerating machine oil contains an antioxidant (B) or an acid scavenger (C), thereby preventing the acid value of the refrigerating machine oil from increasing at high temperatures and improving the high-temperature oxidation stability of the refrigerating machine oil. Is possible. Further, the refrigerating machine oil contains both the antioxidant (B) and the acid scavenger (C), thereby further suppressing the increase in the acid value of the refrigerating machine oil and further improving the high-temperature oxidation stability of the refrigerating machine oil. It becomes possible to make it.

Hereinafter, the antioxidant (B) and the acid scavenger (C) will be described in detail.
(Antioxidant (B))
Examples of the antioxidant (B) include phenolic antioxidants and amine antioxidants.
Examples of phenolic antioxidants include monophenolic antioxidants and polyphenolic antioxidants.
Monophenol antioxidants include n-octyl-3- (3,5-di-t-butyl 4-hydroxyphenyl) propionate, 6-methylheptyl-3- (3,5-di-t-butyl- Alkyl-3- (3,5-di-t-butyl-4-hydroxy) such as 4-hydroxyphenyl) propionate and n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Phenyl) propionate (alkyl groups include those having 4 to 20 carbon atoms, preferably 8 to 18 carbon atoms); 2,6-di-t-butyl-4-methylphenol, 2,6 -2,6-di-t-butyl-4-alkylphenol (dialkyl having 1 to 4 carbon atoms) such as di-t-butyl-4-ethylphenol; 2,4-dimethyl-6-t- Butylphenol, 2,6-di -t- amyl -p- cresol.

Polyphenol antioxidants include 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-bis (2,6-di-t-butylphenol), 4,4 ′. -Bis (2-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 4, '-Thiobis (2-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 2,2'-thiobis (4-methyl-6-t-butylphenol) Bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, thiodiethylenebis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate] and the like.

Examples of amine-based antioxidants include dialkyldiphenylamines such as 4,4′-dibutyldiphenylamine and 4,4′-dioctyldiphenylamine, and phenyl-α-naphthylamines such as alkylphenyl-α-naphthylamine and phenyl-α-naphthylamine. N, N′-di-phenyl-p-phenylenediamine and the like.

As the antioxidant (B), a phenolic antioxidant is preferable. Among the above-mentioned phenolic antioxidants, 2,6-di-t-butyl-4-alkylphenol is more preferable, and 2,6-di-t-butyl-4-methylphenol is most preferable. By using these phenolic antioxidants as the antioxidant (B), an increase in the acid value of the refrigerating machine oil can be appropriately prevented, and the oxidation stability at high temperatures can be easily improved.

The content of the antioxidant (B) in the refrigerating machine oil is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, based on the total amount of the refrigerating machine oil, and 0.15 More preferably, it is ˜1% by mass. By making the refrigerating machine oil contain these lower limit values or more, the antioxidant sufficiently suppresses an increase in the acid value of the refrigerating machine oil and facilitates enhancing high-temperature stability. Moreover, it becomes easy to exhibit the effect corresponding to content by setting it as these upper limit values or less.
In addition, an antioxidant (B) may be used individually by 1 type, and may use 2 or more types together.

(Acid scavenger (C))
Examples of the acid scavenger (C) include epoxy compounds, and more specifically, glycidyl ether compounds, cyclohexene oxide, α-olefin oxide, epoxidized soybean oil, and the like, with glycidyl ether compounds being preferred.
Examples of the glycidyl ether compound include aliphatic mono- or polyhydric alcohols having 3 to 30, preferably 4 to 24, more preferably 6 to 16 carbon atoms, or an aromatic compound-derived glycidyl derived from an aromatic compound. Ether. The aliphatic mono- or polyhydric alcohol may be linear, branched or cyclic, and may be saturated or unsaturated, but is preferably a saturated aliphatic monoalcohol.
In the case of an aromatic polyhydric alcohol or an aromatic compound containing two or more hydroxyl groups, it is preferable that all of the hydroxyl groups are glycidyl etherified from the viewpoint of suppressing the stability of the refrigerating machine oil and the hydroxyl value.
Examples of the glycidyl ether compound include phenyl glycidyl ether, alkyl glycidyl ether, and alkylene glycol glycidyl ether. Among these, linear, branched, and cyclic C6-C16 saturated aliphatic monoalcohols are particularly derived. Of glycidyl ether (that is, alkyl glycidyl ether having an alkyl group having 6 to 16 carbon atoms) is more preferable. Examples of such glycidyl ether include 2-ethylhexyl glycidyl ether, isononyl glycidyl ether, decyl glycidyl ether, lauryl glycidyl ether, myristyl glycidyl ether, and 2-ethylhexyl glycidyl ether is most preferable. By using an alkyl glycidyl ether such as 2-ethylhexyl glycidyl ether, an increase in the acid value of the refrigerating machine oil can be appropriately prevented, and oxidation stability at high temperatures can be easily improved.

The content of the acid scavenger (C) in the refrigerating machine oil is preferably 0.1 to 10% by mass based on the total amount of the refrigerating machine oil. By setting the content of the acid scavenger (C) to 0.1% by mass or more, the acid in the refrigeration oil can be appropriately captured, and the acid value of the refrigeration oil can be effectively prevented from increasing, and the high temperature stability It becomes easy to raise. Moreover, the effect corresponding to content can be show | played by setting it as 10 mass% or less.
The content of the acid scavenger (C) is more preferably 0.4 to 5% by mass, further preferably 0.5 to 5% by mass, particularly preferably 0.5 to 3% by mass, and most preferably 0.5 to 2% by mass. When the content of the acid scavenger (C) is increased as described above, the acid value of the refrigerating machine oil can be more effectively prevented from increasing. In addition, an acid capture agent (C) may be used individually by 1 type, and may use 2 or more types together.
Moreover, an acid scavenger (C) can further suppress an increase in acid value by using together with the above-mentioned antioxidant (B).

(Extreme pressure agent (D))
The refrigerating machine oil preferably further contains an extreme pressure agent (D). By containing the extreme pressure agent (D), the refrigerating machine oil has good wear resistance at high temperatures and can further improve lubricity.
Examples of the extreme pressure agent (D) include phosphorus-based extreme pressure agents. Examples of the phosphorus extreme pressure agent include phosphoric acid esters, phosphorous acid esters, acidic phosphoric acid esters, acidic phosphorous acid esters, and amine salts thereof.
Examples of phosphate esters include triaryl phosphate, trialkyl phosphate, monoalkyl diaryl phosphate, dialkyl monoaryl phosphate, and trialkenyl phosphate. The “aryl” described in the extreme pressure agent (D) is a concept including not only a functional group consisting of only an aromatic ring but also alkylaryl and arylalkyl.

Specific examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, benzyl diphenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, propyl phenyl diphenyl phosphate, dipropyl phenyl phenyl phosphate, and ethyl phenyl diphenyl phosphate. , Diethyl phenylphenyl phosphate, triethyl phenyl phosphate, tripropyl phenyl phosphate, butyl phenyl diphenyl phosphate, dibutyl phenyl phenyl phosphate, tributyl phenyl phosphate, triaryl phosphate, tributyl phosphate, ethyl dibutyl phosphate, trihexyl phosphate, tri (2-ethylhexyl) ) Phosphae , It may be mentioned tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tri palmityl phosphate, alkyl phosphates such as tristearyl phosphate, ethyl diphenyl phosphate, and trioleyl phosphate.

Examples of acidic phosphate esters include various alkyl acid phosphates and dialkyl acid phosphates. Examples of phosphites include various trialkyl phosphites, triaryl phosphites, monoalkyl diaryl phosphites, dialkyl monoaryl phosphites, and trialkenyl phosphites. Examples of the acidic phosphite include various dialkyl hydrogen phosphites, dialkenyl hydrogen phosphites, and diaryl hydrogen phosphites. The phosphorus extreme pressure agent may be a phosphate ester containing a sulfur atom such as trithiophenyl phosphate. In addition, as an amine salt, the amine salt of acidic phosphate ester or acidic phosphite is mentioned. The amine salt that forms the amine salt may be a primary, secondary, or tertiary amine.

Among the above-mentioned extreme pressure agents (D), phosphate esters are preferable, triaryl phosphate is more preferable, and tricresyl phosphate is most preferable. By using a triaryl phosphate such as tricresyl phosphate, lubricity at a high temperature tends to be good. Other preferable examples include trithiophenyl phosphate, tri (nonylphenyl) phosphite, dioleyl hydrogen phosphite, and 2-ethylhexyl diphenyl phosphite.
The content of the extreme pressure agent (D) in the refrigeration oil is preferably 0.1 to 5% by mass based on the total amount of the refrigeration oil. When the content is 0.1% by mass or more, the lubricity tends to be good. Moreover, it becomes easy to acquire the effect corresponding to content by setting it as 5 mass% or less. From these viewpoints, the content of the extreme pressure agent (D) is more preferably 0.3 to 3% by mass, further preferably 0.5 to 3% by mass, and most preferably 0.5 to 2% by mass.
In addition, when the extreme pressure agent (D) is added to the refrigerating machine oil, the acid value tends to increase, but by using the antioxidant (B) and the acid scavenger (C) in combination, the extreme pressure agent (D ) Can be suppressed more appropriately.

As described above, the refrigerating machine oil in the present embodiment particularly preferably contains any of the antioxidant (B), the acid scavenger (C), and the extreme pressure agent (D). The contents of the components (D) to (D) are also as described above. That is, the content of each of the polyvinyl ether compound (A), the antioxidant (B), the acid scavenger (C), and the extreme pressure agent (D) is 70 to 99.7% by mass based on the total amount of refrigerating machine oil, It is preferably 0.1 to 5% by mass, 0.1 to 10% by mass, and 0.1 to 5% by mass, preferably 75 to 99.3% by mass, 0.1 to 3% by mass, 0.4 to 5%. More preferably, it is 80% to 98.4% by weight, 0.15% to 1% by weight, 0.5% to 5% by weight, and 0.5% to 3% by weight. More preferably, it is 80 to 98.4% by mass, 0.15 to 1% by mass, 0.5 to 2% by mass, and most preferably 0.5 to 2% by mass.
In addition, preferred compounds containing the components (B) to (D) are the same as described above. That is, it is preferable that the antioxidant (B) is a phenolic antioxidant, the acid scavenger (C) is a glycidyl ether compound, the extreme pressure agent (D) is a phosphate ester, and the antioxidant (B) is 2 , 6-di-t-butyl-4-alkylphenol, the acid scavenger (C) is preferably alkyl glycidyl ether, the extreme pressure agent (D) is triaryl phosphate, and the antioxidant (B) is 2, More preferably, 6-di-t-butyl-4-methylphenol, the acid scavenger (C) is 2-ethylhexyl glycidyl ether, and the extreme pressure agent (D) is tricresyl phosphate.

(Other additives)
The refrigerating machine oil may be composed of a base oil and (B) or (C) component or both, or from a base oil, (B) or (C) component or both, and (D) component. However, additives other than these components (B) to (D) may be further contained.
Examples of such additives include oxygen scavengers, oiliness improvers, copper deactivators, rust inhibitors, and antifoaming agents. These additives may be used alone or in combination of two or more.

Examples of the oxygen scavenger include 4,4′-thiobis (3-methyl-6-tert-butylphenol), diphenyl sulfide, dioctyl diphenyl sulfide, dialkyl diphenylene sulfide, benzothiophene, dibenzothiophene, phenothiazine, benzothiapyran, thiapyran, thianthrene, Examples thereof include sulfur-containing aromatic compounds such as dibenzothiapyran and diphenylene disulfide, aliphatic unsaturated compounds such as various olefins, dienes and trienes, and terpenes having a double bond.
Examples of oil improvers 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, Aliphatic saturated and unsaturated monoalcohols such as lauryl alcohol, oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine, oleylamine, aliphatic saturated and unsaturated monocarboxylic amides such as lauric acid amide, oleic acid amide, Examples thereof include partial esters of polyhydric alcohols such as glycerin and sorbitol and aliphatic saturated or unsaturated monocarboxylic acids.

Examples of the copper deactivator include N- [N, N′-dialkyl (alkyl group having 3 to 12 carbon atoms) aminomethyl] triazole.
Examples of the rust inhibitor include metal sulfonates, aliphatic amines, organic sulfonic acid metal salts, organic phosphoric acid metal salts, alkenyl succinic acid esters, and polyhydric alcohol esters.
Examples of the antifoaming agent include silicone oils such as dimethylpolysiloxane, polymethacrylates, and the like.
The content of each of these refrigerating machine oil additives is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, based on the total amount (100% by mass) of the refrigerating machine oil.

Refrigerating machine oil is excellent in compatibility with R32 refrigerant having a low global warming potential even in a low temperature environment. Specifically, the two-layer separation temperature on the low temperature side of the refrigerating machine oil with the R32 refrigerant is preferably −15 ° C. or lower, more preferably −30 ° C. or lower, and further preferably −40 ° C. or lower.
In the present specification, the above-mentioned “two-layer separation temperature of the refrigerating machine oil on the low temperature side with the R32 refrigerant” is the refrigerating machine oil / R32 refrigerant = 15/85 (mass ratio) of the refrigerating machine oil and the R32 refrigerant. By using a mixture as a sample, the value measured by the method described in Examples is meant.

[Method for producing refrigerating machine oil]
The manufacturing method of the refrigerating machine oil which concerns on one Embodiment of this invention is a manufacturing method of the refrigerating machine oil for refrigerant | coolants containing difluoromethane (R32), Comprising: Polyvinyl containing the structural unit (a1) which has a methoxyethyl group in a side chain A refrigerating machine oil is produced by blending at least one selected from the group consisting of an antioxidant (B) and an acid scavenger (C) with an ether compound (A).
In this production method, the polyvinyl ether compound (A) is further blended with additives other than the antioxidant (B) and the acid scavenger (C) such as the extreme pressure agent (D) as described above. Alternatively, a base oil other than the compound (A) may be blended. In this production method, the details of the components (A) to (D), other additives, other base oils, and the obtained refrigerating machine oil are as described above.

[Composition for refrigerator]
The refrigerating machine oil is used by being mixed with a refrigerant. In the present specification, a mixture of refrigerant in refrigeration oil is referred to as a “composition for a refrigeration machine”. That is, the composition for refrigerators which concerns on one Embodiment of this invention contains the refrigerant | coolant containing difluoromethane (R32) and the above-mentioned refrigerator oil. In the composition for a refrigerator, the content ratio between the refrigerator oil and the refrigerant (refrigerator oil / refrigerant) is preferably 1/99 to 99/1, more preferably 5/95 to 60/40, in mass ratio. .

[Refrigerant]
The refrigerant may be composed of the R32 refrigerant alone, but may be a mixture of the R32 refrigerant and other refrigerants. Examples of other refrigerants include fluorinated hydrocarbon refrigerants, natural refrigerants such as hydrocarbon refrigerants, carbon dioxide, and ammonia. Other refrigerants may be used alone or in combination of two or more.
In the refrigerant, the content of the R32 refrigerant is preferably 10 to 100% by mass, more preferably 20 to 100% by mass, still more preferably 30 to 100% by mass, and still more preferably, based on the total amount (100% by mass) of the refrigerant. Is 50 to 100% by mass, particularly preferably 70 to 100% by mass. Among these, the refrigerant | coolant of R32 independent (100 mass%) is the most preferable.

Examples of the fluorinated hydrocarbon refrigerant include a saturated fluorinated hydrocarbon refrigerant and an unsaturated fluorinated hydrocarbon refrigerant.
Examples of the saturated fluorinated hydrocarbon refrigerant include fluorides of alkanes having 1 to 4 carbon atoms other than R32, preferably fluorides of alkanes having 2 to 3 carbon atoms, and fluorides of alkane (ethane) having 2 carbon atoms. Is more preferable. For example, 1,1,1,2,2-pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1,2,2-tetrafluoroethane (R134), 1 , 1,1-trifluoroethane (R143a), 1,1,2-trifluoroethane (R143), 1,1-difluoroethane (R152a), among which R125 and R134a are preferred.
These saturated fluorinated hydrocarbon refrigerants can be used as a mixture of two or more.
When a fluorinated hydrocarbon refrigerant is used as the refrigerant, the refrigerant used in this embodiment is specifically a mixture of R32, R125, and R134a such as R407A, R407C, and R407E, and a mixture of R32 and R125 such as R410A. Etc. are mentioned as preferred examples, and among these, R410A is more preferred.

Examples of the unsaturated fluorinated hydrocarbon refrigerant include those having a carbon-carbon double bond, such as a linear or branched chain olefin having 2 to 6 carbon atoms and a fluorinated product of a cyclic olefin having 4 to 6 carbon atoms. It is done. Of these, propene fluoride is preferred, propene having 3 to 5 fluorine atoms introduced therein is more preferred, and propene having 4 fluorine atoms introduced is most preferred. As other than propene fluoride, ethylene fluoride is also preferred, ethylene having 1 to 3 fluorine atoms introduced is more preferred, and ethylene having 3 fluorine atoms introduced is most preferred.
Specific examples of preferable unsaturated fluorinated hydrocarbon refrigerants include 1,2,3,3,3-pentafluoropropene (R1225ye), 2,3,3,3-tetrafluoropropene (R1234yf), 1,3,3, 3,3-tetrafluoropropene (R1234ze), 1,2,3,3-tetrafluoropropene (R1234yz), 1,1,2-trifluoroethylene (R1123) and the like, among which R1234yf, R1234ze , R1123 is preferred.
When these unsaturated fluorinated hydrocarbon refrigerants are mixed, the content is preferably 20% by mass or more based on the total amount of refrigerant (100% by mass).
These unsaturated fluorinated hydrocarbon refrigerants may be used in combination with the above-mentioned saturated fluorinated hydrocarbon refrigerant.

Natural refrigerants include hydrocarbon refrigerants such as propane (R290), n-butane, isobutane (R600a), 2-methylbutane, n-pentane, cyclopentaneisobutane, normal butane, carbon dioxide (carbon dioxide), and ammonia. Among these, propane, isobutane, carbon dioxide, and ammonia are preferable.
These natural refrigerants may be used in combination with the above-mentioned fluorinated hydrocarbon refrigerant.

[refrigerator]
A refrigerator according to an embodiment of the present invention uses the above-described refrigerator oil or refrigerator oil composition, and the refrigerator oil or refrigerator oil composition is used by filling the refrigerator. That is, the refrigerator which concerns on one Embodiment of this invention is a refrigerator containing the above-mentioned refrigerator oil or refrigerator oil composition. As the refrigerator, a compression type refrigerator is preferable, and a refrigeration cycle including 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 evaporation It is more preferable to have a refrigeration cycle equipped with a vessel.
Refrigerator oil is used, for example, to lubricate sliding portions provided in a compressor or the like.
The sliding portion is not particularly limited, but any of the sliding portions preferably contains a metal such as iron, and preferably slides between metal and metal.
As the refrigerator, for example, it is applied to a car air conditioner, an air conditioner, a gas heat pump (GHP), a refrigerator, a vending machine, a refrigeration system such as a showcase, a hot water supply system such as a water heater, floor heating, a heating system, etc. However, it is preferably applied to air conditioning applications.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the measurement methods of various properties are as follows.

(1) Kinematic viscosity at 40 ° C. Measured according to JIS K2283: 2000.
(2) Viscosity index Measured according to JIS K2283: 2000.
(3) Number average molecular weight (Mn)
Standard polystyrene conversion values measured under the following conditions using a gel permeation chromatograph device (manufactured by Agilent, “1260 type HPLC”) were used.
(Measurement condition)
・ Column: Two “Shodex LF404” sequentially connected ・ Column temperature: 35 ° C.
・ Developing solvent: Chloroform ・ Flow rate: 0.3 mL / min
(4) Measurement of two-layer separation temperature on the low temperature side with R32 refrigerant Refrigeration oil and refrigerant (R32) were 0.45 g and 2.55 g (refrigeration oil / Refrigerant (mass ratio) = 15/85) was charged and held in a thermostatic bath. The temperature of the thermostatic chamber was lowered from room temperature (25 ° C.) to −50 ° C. at a rate of 1 ° C./min, and the two-layer separation temperature on the low temperature side was measured. In the table, those that were not separated into two layers until −50 ° C. are indicated as “−50>” in the table. The temperature was raised from room temperature at a rate of 1 ° C./min, and the two-layer separation temperature on the high temperature side was measured.
(5) Thermal stability test In an autoclave with an internal volume of 200 mL, refrigeration oil and R32 refrigerant (ratio of refrigeration oil / R32 refrigerant = 30 g / 30 g, water content in oil 500 mass ppm), and metal catalyst, iron Then, the tube was filled with copper and aluminum, sealed, and kept for 336 hours under conditions of air pressure of 18.7 kPa and temperature of 175 ° C., and then the acid value of the refrigerating machine oil was measured. The acid value was measured by the indicator method according to “Lubricating oil neutralization test method” defined in JIS K 2501: 2003.
(6) Lubricity test Using a sealed block-on-ring friction tester (LFW-1), the amount of ring wear when each refrigeration oil was used was measured under the following conditions in an R32 refrigerant environment.
Ring: FC250 Block: SKH51 Rotation speed: 1000rpm
Familiarization: Load 300N x 1min Load: 500N Time: 60min Oil temperature: 80 ° C Refrigerant pressure: 0.4MPa

Preparation Example 1 [Preparation of catalyst]
6 g of nickel diatomaceous earth catalyst (manufactured by JGC Catalysts & Chemicals, trade name “N113”) and 300 g of isooctane were added to a 2 L autoclave made of SUS316L.
The inside of the autoclave was purged with nitrogen and then purged with hydrogen, then heated to 140 ° C. with a hydrogen pressure of 3.0 MPaG, held at 140 ° C. for 30 minutes, and then cooled to room temperature.
Then, after the inside of the autoclave was purged with nitrogen, 10 g of acetaldehyde diethyl acetal was added into the autoclave, the atmosphere was replaced with nitrogen again, and then the atmosphere was replaced with hydrogen. Hold for a minute. At this time, the pressure in the autoclave was increased by the temperature rise, while a decrease in hydrogen pressure was observed due to the reaction of acetaldehyde diethyl acetal. When the hydrogen pressure became 3.0 MPaG or less, hydrogen was injected into the autoclave and adjusted so that the hydrogen pressure was maintained at 3.0 MPaG.
After holding, it was cooled to room temperature and once depressurized, and after the inside of the autoclave was again purged with nitrogen, it was depressurized.

Example 1
(Synthesis of polyvinyl ether (A) (PVE1))
To a glass 300 mL flask equipped with a stirrer, 49 g of toluene, 19.2 g of acetaldehyde bis (methoxyethyl) acetal, 8.5 g of acetaldehyde diethyl acetal, and 0.1 g of boron trifluoride diethyl ether complex were added. Further, 20.6 g (0.2 mol) of methoxyethyl vinyl ether and 130.6 g (1.8 mol) of ethyl vinyl ether were added to the separately prepared Erlenmeyer flasks to prepare a monomer mixed solution.
Then, the stirrer was activated, and the monomer mixture in the Erlenmeyer flask was supplied to the stirred system of the 300 mL flask by a pump over 4 hours, and stirring was further continued for 5 minutes after the completion of the supply. During the supply of the monomer mixture, the system was constantly stirred, and the temperature in the system was controlled at 25 ° C. using a water bath.
Next, 5 g of an adsorbent (manufactured by Kyowa Chemical Industry Co., Ltd., product name “KYOWARD 500SH”) was added to the 300 mL flask system and stirred for 1 hour. And the obtained reaction liquid was filtered, the solvent and the light part were removed from the said filtrate using the rotary evaporator, and the crude product was obtained.
Thereafter, 120 g of the obtained crude product and 300 g of isooctane were added to the 2 L autoclave containing the catalyst prepared in Preparation Example 1, and the atmosphere inside the autoclave was replaced with hydrogen. Then, the hydrogen pressure was maintained at 3.5 MPa, and the system was stirred. However, the temperature was raised to 140 ° C. over 30 minutes, and further reacted at 140 ° C. for 3 hours.
After completion of the reaction, the reaction solution was cooled to room temperature and depressurized to normal pressure. And the reaction liquid was filtered, the solvent, the water | moisture content, etc. were removed from the obtained filtrate using the rotary evaporator, and PVE1 was obtained.
PVE1 includes a structural unit (a1) in which R ¹ to R ³ in general formula (1) are hydrogen atoms, R ⁴ to R ⁶ in general formula (2) are hydrogen atoms, r is 0, and R ⁸ is The structural unit (a2) which is an ethyl group is included. Further, the content of the structural unit (a1) is 10 mol% and the content of the structural unit (a2) is 90 mol% with respect to all the structural units (100 mol%) of PVE1 estimated from the charged amount. .

(Preparation of refrigeration oil)
Using the PVE1 obtained above and the following antioxidant, acid scavenger and extreme pressure agent, a refrigerating machine oil was prepared with the formulation shown in Table 1. The two-layer separation temperature of the refrigerating machine oil of Example 1 was measured, and the measurement results are shown in Table 1. Table 1 also shows the properties (40 ° C. kinematic viscosity, viscosity index (VI)) of PVE1, which is a base oil.
Antioxidant: 2,6-di-t-butyl-4-methylphenol Acid scavenger: 2-ethylhexyl glycidyl ether Extreme pressure agent: tricresyl phosphate

Examples 2-8
The amount of methoxyethyl vinyl ether added to the Erlenmeyer flask was changed to 0.4 to 2.0 mol so that each structural unit in the polyvinyl ether compound (A) would be the mol% shown in Table 1, The same operation as in Example 1 was carried out except that the addition amount was changed to 1.6 to 0 mol to obtain PVE2 to PVE8. Table 1 shows the properties of PVE2 to PVE8 used in Examples 2 to 8, respectively.

Comparative Examples 1 and 2
It implemented like Example 1 except having changed the base oil to be used to the following PVE9 and 10 as shown in Table 1, respectively. The properties of the base oils used in Comparative Examples 1 and 2 are as shown in Table 1.
PVE9: Copolymer of ethyl vinyl ether (EVE) and isobutyl vinyl ether (iBuVE) (molar ratio (EVE / iBuVE) = 90/10)
PVE10: Polyethyl vinyl ether

* In each table, “MeOEt” represents the structural unit (a1) in which R ¹ to R ³ in the general formula (1) are hydrogen atoms, and “Et” represents R ⁴ to R ⁶ in the general formula (2). The structural unit (a2) in which a hydrogen atom, r is 0, and R ⁸ is an ethyl group, “iBu” is a hydrogen atom, r is 0, and R ⁸ is an isobutyl group in R ⁴ to R ⁶ in the general formula (2) Is the structural unit (a2).

Examples 9 to 14 and Comparative Example 3
Using the above-mentioned PVE3, antioxidant, acid scavenger, and extreme pressure agent, refrigerating machine oils having the composition shown in Table 2 were prepared, and a thermal stability test was performed on each refrigerating machine oil. Table 2 shows the acid values after completion of the thermal stability test.

Examples 15 to 18 and Comparative Example 4
Using the above-described PVE3, PVE10, antioxidant, acid scavenger, and extreme pressure agent, refrigerating machine oils having the composition shown in Table 3 were prepared, and a lubricity test was performed on each refrigerating machine oil. Table 3 shows the ring wear after the lubricity test.

As shown in Table 1, in each Example, the polyvinyl ether compound constituting the base oil of the refrigerating machine oil contains the structural unit (a1) having a methoxyethyl group in the side chain, whereby the R32 refrigerant is used. It was possible to improve the compatibility, particularly in a low temperature environment.
Moreover, as shown in Table 2, even after the refrigeration oil is heat-degraded by blending an antioxidant, an acid scavenger, or both of them into the base oil composed of the polyvinyl ether compound (A). The acid value was lowered and the high-temperature oxidation stability was improved. When an extreme pressure agent is blended, the high-temperature oxidation stability tends to be low. However, as shown in Table 2, when an appropriate amount of an antioxidant and an acid scavenger is blended, the oxidation stability due to the blending of the extreme pressure agent is reduced. It was possible to suppress the decrease.
Further, as shown in Table 3, when the polyvinyl ether compound (A) was used for the base oil of the refrigerating machine oil, the amount of wear in the lubricity test was reduced, and the lubricity in a high temperature environment was improved. Moreover, lubricity was further improved by blending an extreme pressure agent.

On the other hand, as is clear from Comparative Examples 1, 2, and 4, if the refrigerating machine oil does not contain the polyvinyl ether compound (A), the compatibility with the R32 refrigerant is not good, and at high temperatures. The lubricity was not sufficient (see Tables 1 and 3). Furthermore, as apparent from Comparative Example 3, unless the refrigerating machine oil contains an antioxidant and an acid scavenger, the thermal stability could not be sufficiently improved (see Table 2).

Claims

Refrigerating machine oil for refrigerant containing difluoromethane (R32),
A polyvinyl ether compound (A) containing a structural unit (a1) having a methoxyethyl group in the side chain, and at least one selected from the group consisting of an antioxidant (B) and an acid scavenger (C) Refrigerator oil.
The refrigerating machine oil according to claim 1, wherein the content of the antioxidant (B) is 0.1 to 5% by mass based on the total amount of the refrigerating machine oil.
The refrigerating machine oil according to claim 1 or 2, wherein the content of the acid scavenger (C) is 0.1 to 10% by mass based on the total amount of the refrigerating machine oil.
The refrigerating machine oil according to any one of claims 1 to 3, comprising both an antioxidant (B) and an acid scavenger (C).
The refrigerating machine oil according to any one of claims 1 to 4, wherein the antioxidant (B) is a phenolic antioxidant and the acid scavenger (C) is a glycidyl ether compound.
The refrigerating machine oil according to any one of claims 1 to 5, wherein the refrigerating machine oil further contains an extreme pressure agent (D).
The refrigerator oil according to claim 6, wherein the content of the extreme pressure agent (D) is 0.1 to 5% by mass based on the total amount of the refrigerator oil.
The refrigerating machine oil according to claim 6 or 7, wherein the extreme pressure agent (D) is a phosphate ester.
The refrigerating machine oil according to any one of claims 1 to 8, wherein the structural unit (a1) is represented by the following general formula (1).

(In the general formula (1), R 1 , R 2 , and R 3 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms.)
The polyvinyl ether compound (A) includes a structural unit (a2) represented by the following general formula (2) different from the structural unit (a1) together with the structural unit (a1). The refrigerating machine oil according to claim 1.

(In the above formula (2), R 4 , R 5 , and R 6 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. R 7 represents 2 having 2 to 10 carbon atoms. R represents an integer of 0 to 10. R 8 represents a hydrocarbon group having 1 to 10 carbon atoms, provided that R 7 represents an ethylene group (—CH 2 CH 2 —). And when R 8 is a methyl group, r is not 1.)
The content of the structural unit (a1) is 10 mol% or more and 70 mol% or less based on all structural units (100 mol%) of the polyvinyl ether compound (A). Refrigerating machine oil described in 1.
The refrigerating machine oil according to any one of claims 1 to 11, wherein the polyvinyl ether compound (A) has a kinematic viscosity at 40 ° C of 10 to 400 mm 2 / s and a viscosity index of 90 or more.
The refrigerant according to any one of claims 1 to 12, wherein the refrigerant is R32 alone or a mixture of R32 and at least one refrigerant selected from the group consisting of a fluorinated hydrocarbon refrigerant, a hydrocarbon refrigerant, carbon dioxide, and ammonia. Refrigeration machine oil given in any 1 paragraph.
A refrigerating machine composition comprising the refrigerating machine oil according to any one of claims 1 to 13 and the refrigerant.
A method for producing a refrigerating machine oil for refrigerant containing difluoromethane (R32),
At least one selected from the group consisting of an antioxidant (B) and an acid scavenger (C) is added to the polyvinyl ether compound (A) containing the structural unit (a1) having a methoxyethyl group in the side chain. A method for producing refrigerating machine oil, which produces refrigerating machine oil.