JP2976157B2 - Composition for working fluid of refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for a working fluid of a refrigerator, and more particularly to a composition for a working fluid of a compression refrigerator for an electric refrigerator or the like.

[0002]

2. Description of the Related Art Recently,
The use of dichlorodifluoromethane (CFC12), which is used in refrigerators and car coolers to protect the ozone layer, has been regulated and will be banned in the future. Therefore, as a substitute for this CFC12, a hydrofluorocarbon that does not destroy the ozone layer, for example, 1,
1,1,2-tetrafluoroethane (HFC134a)
Is being developed.

However, hydrofluorocarbons are
Since the polarity is higher than that of FC12, if a lubricating oil such as a naphthenic mineral oil, a poly-α-olefin, or an alkylbenzene, which has been generally used as a refrigerating machine oil, is used, the compatibility between these lubricating oils and hydrofluorocarbons is poor. Causes two-layer separation at low temperatures. If two-layer separation occurs, oil return will deteriorate, and a thick oil film will adhere near the condenser or evaporator as a heat exchanger, hindering heat transfer, and also cause poor lubrication and foaming during startup. It causes defects. Therefore, conventional refrigerating machine oil cannot be used as refrigerating machine oil under these new refrigerant atmospheres.

[0004] In addition, the lubricating effect of the CFC 12 is partially decomposed to generate hydrogen chloride, and this hydrogen chloride reacts with the friction surface to form a chloride film and improve lubricating effect. was there. However, since such effects cannot be expected for hydrofluorocarbons containing no chlorine atom, lubricating oils that are more excellent than conventional oils are required for refrigerating machine oils used with hydrofluorocarbons. Further, the refrigerating machine oil used together with the hydrofluorocarbon needs to have good thermal stability in the presence of the hydrofluorocarbon.

In addition, since the compression refrigerator of an electric refrigerator contains an organic material used for a motor such as an insulating material and an enameled wire, the working fluid comprising hydrofluorocarbon and refrigerating machine oil cannot be used. It is necessary that the organic material has no adverse effect, and that the electrical insulation be good. Hydrofluorocarbons such as 1,1,1,2-tetrafluoroethane (H
US Pat. No. 4,755,316 (JP-A-2-502385) as a refrigerating machine oil that can be used together with FC134a)
Polyether compounds are disclosed in the specification, JP-A-1-198694, JP-A-1-256594, and the like.

[0006] Since the polyether compound has a higher polarity than the naphthenic mineral oil, its compatibility with HFC134a at low temperatures is certainly good. However, U.S. Pat.
As described in the specification of US Pat. No. 5,316, the polyether compound has a problem of causing a two-layer separation when the temperature rises, and cannot be used as a refrigerating machine oil. The polyether compound also has some other problems. One is that the electrical insulation is poor. This is a very big problem and cannot be used for refrigerators for electric refrigerators. Another problem is high hygroscopicity. Due to the water in the polyether compound, the thermal stability in the presence of HFC134a is deteriorated, and the organic material such as a PET film is hydrolyzed.

[0007] Ester-based compounds have been developed in order to improve the problems of the polyether compounds with regard to the electrical insulation and the hygroscopicity. For example, as a refrigerating machine oil that can be used together with 1,1,1,2-tetrafluoroethane (HFC134a), US Pat. No. 4,851,144 (Japanese Patent Application Laid-Open No. H2-276894) and Japanese Patent Application Laid-Open No. H2-15693 disclose. ,
Blended oils of polyether and ester oils are disclosed, British Patent 2,261,541, U.S. Patent 5,021,179, European Patents 445,610 and 445,611,
International Publication No. 90/12849 (Japanese Patent Publication No. 3-505602),
JP-A-3-88892, JP-A-3-28991, JP-A-3-289
No. 92, JP-A-3-79091, JP-A-3-200895, JP-A-3-200896, JP-A-3-217494, JP-A-3-227397, JP-A-3-252497 Gazette, JP-A-4-
No. 4294 discloses an ester oil.

Such ester compounds have excellent compatibility with hydrofluorocarbons, have excellent thermal stability in the presence of hydrofluorocarbons, and have extremely excellent electrical insulation properties as compared with polyether compounds. And its moisture absorption is very low. However, compared to the conventional working fluid CFC12-mineral oil system, the hydrofluorocarbon-ester oil system has a higher polarity for both chlorofluorocarbons and oils and tends to contain water. Although the refrigerator is provided with a drier for removing water by molecular sieve, the ester is hydrolyzed by remaining water which cannot be removed sufficiently to produce carboxylic acid. It has been pointed out that the generated carboxylic acid corrodes the metal and causes abrasion and copper plating. Therefore, there is a need in the art to develop an ester having excellent hydrolysis stability.

[0009] An object of the present invention is to provide a specific ester which is excellent in compatibility with hydrofluorocarbons, heat stability, electric insulation and moisture absorption, and particularly excellent in hydrolytic stability as compared with conventional ones. To provide a composition for a working fluid of a refrigerator.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have found that certain ester compounds can achieve the above object.
The present invention has been completed. That is, the present invention provides a refrigerating machine oil comprising an ester represented by the general formula (I) as a base oil , a hydrofluorocarbon , and an epoxycyclohexyl.
Compound having an epoxy group and epoxycyclopentyl group
It is intended to provide a composition for a working fluid of a refrigerator containing at least one selected from the group consisting of the following compounds .

[0011]

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(Wherein, R ¹ represents an alkyl group having 1 to 9 carbon atoms, R ² and R ³ represent an alkyl group having 2 to 10 carbon atoms. R ¹ , R ² and R ³ are the same or different. And the total number of carbon atoms of R ¹ , R ² and R ³ is 5 or more and 13 or more.
It is as follows. R ⁴ represents a residue of an n-valent alcohol having 2 to 30 carbon atoms. n is an integer of 2 to 6, and n

[0013]

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May be the same or different. The ester used in the present invention is synthesized from a divalent to hexavalent alcohol having 2 to 30 carbon atoms and a carboxylic acid represented by the general formula (II) or a derivative thereof.

[0015]

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In the general formula (II), R ¹ has ¹ carbon atom
To 9 alkyl groups, R ² and R ³ are alkyl groups having 2 to 10 carbon atoms. R ¹ , R ² and R ³ may be the same or different, and the total number of carbon atoms of R ¹ , R ² and R ³ is 5 or more and 13 or less.

The divalent to hexavalent alcohol used for the production of the ester in the present invention has 2 to 30, preferably 2 to 20, more preferably 2 to 10 carbon atoms. If the number of carbon atoms is more than 30, the viscosity becomes high and the compatibility with the hydrofluorocarbon-based refrigerant becomes poor. Also,
The number of hydroxy groups in these alcohols is 2 to 6, preferably 2 to 4. If the number of hydroxy groups is more than 6, the viscosity becomes too high. Among these alcohols, saturated aliphatic alcohols are preferred from the viewpoint of heat resistance. Specifically, neopentyl glycol,
2-ethyl-2-methyl-1,3-propanediol, 2
-Methyl-2-propyl-1,3-propanediol, 2
-Isopropyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-n
-Butyl-2-ethyl-1,3-propanediol, hindered alcohols such as trimethylolethane, trimethylolpropane, trimethylolnonane, pentaerythritol and dipentaerythritol, or ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol , Dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2
-Methyl-1,2-propanediol, 2-methyl-1,3
-Propanediol, 1,2-pentanediol, 1,3-
Pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5- Hexanediol, 2-methyl-2,
4-pentanediol, 3,3-dimethyl-1,2-butanediol, 1,7-heptanediol, 2,4-dimethyl-
2,4-pentanediol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,5 -Dimethyl-2,5-hexanediol, 1,9-
Nonanediol, 1,2-decanediol, 1,10-decanediol, glycerin, diglycerin, triglycerin, tetraglycerin, polyglycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1 , 2,3,4
-Polyhydric alcohols such as butanetetrol, sorbitol and mannitol. Among the alcohols shown above, hindered alcohols are particularly excellent from the viewpoint of heat resistance.

The carboxylic acid or a derivative thereof used in the production of the ester in the present invention is a carboxylic acid or a derivative thereof represented by the general formula (II). R ¹ is an alkyl group having 1 to 9 carbon atoms, and R ² and R ³ are alkyl groups having 2 to 10 carbon atoms. These alkyl groups may be linear or branched, and may have a cyclic structure. Specific examples of these include a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopropyl group, a butyl group, a 1-methylpropyl group, and a 2-methylpropyl group.
Methylpropyl group, t-butyl group, pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2 , 2-dimethylpropyl, cyclopentyl, hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1-ethylbutyl, 2-
Ethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, 3,3-dimethylbutyl group , 1-ethyl-2-methylpropyl group, 1-ethyl-1-methylpropyl group, 1,1,2-trimethylpropyl group, 1,2,2, -trimethylpropyl group, cyclohexyl group, cyclopentylmethyl group, methyl Cyclopentyl, heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1-ethylpentyl, 2
-Ethylpentyl group, 2,4 -dimethylpentyl group, 3,4
-Dimethylpentyl group, 1,1 -dimethylpentyl group, 1,
4-dimethylpentyl group, 1-propylbutyl group, 1-
Isopropylbutyl group, 1,3,3-trimethylbutyl group,
1,1-diethylpropyl group, 2,2-diethyl-1-ethylpropyl group, 1,2-diethyl-1-ethylpropyl group, 1-isopropyl-2-methylpropyl group, cycloheptyl group, cyclohexylmethyl group, Methylcyclohexyl group, octyl group, 1-methylheptyl group, 2-methylheptyl group, 1-ethylhexyl group, 2-ethylhexyl group, 1,1,3,3-tetramethylbutyl group, 1,1-diisopropylethyl group, 1-ethyl-1,2,2-trimethylpropyl group, 1,5-dimethylhexyl group, 3,5-dimethylhexyl group, 2-propylpentyl group, 2,4,4-trimethylpentyl group, 1-ethyl- 2-methylpentyl group, 2,2-dimethylhexyl group, 1,1-dimethylhexyl group, cycloheptylmethyl group, dimethylcyclohexyl group, 4-methylcyclohexylmethyl group, cycle Heptylmethyl group, cyclooctyl group, 1-cyclohexylethyl group, 2-cyclohexylethyl group, ethylcyclohexyl group, nonyl group, 1-methyloctyl group, 5-methyloctyl group, 1- (2'-methylpropyl) -3 -Methylbutyl group, 3,5,5-trimethylhexyl group, 1,1-
Diethyl-2,2-dimethylpropyl group, 3-cyclohexylpropyl group, 1,1-dimethylheptyl group, 2,2,4,4
-Tetramethylpentyl group, decyl group, 1-methylnonyl group, 1-propylheptyl group, 3,7-dimethyloctyl group, 2,4,6-trimethylheptyl group, 4-cyclohexylbutyl group, butylcyclohexyl group, 3, 3,5,5-tetramethylcyclohexyl group. R ¹ ,
R ² and R ³ may be the same alkyl group or different alkyl groups. The total number of carbon atoms of R ¹ , R ² and R ³ is 5 or more and 13 or less. Preferably it is 5 or more and 11 or less, more preferably 5 or more and 7 or less. If the total number of carbon atoms exceeds 13, the compatibility of the ester synthesized from the carboxylic acid with the hydrofluorocarbon becomes poor.

Specific examples of such a carboxylic acid having an alkyl group of R ¹ , R ² and R ³ include 2-ethyl-2-methylbutanoic acid, 2,2-diethylbutanoic acid,
2-ethyl-2-methylpentanoic acid, 2-ethyl-2,3
-Dimethylbutanoic acid, 2-isopropyl-2,3-dimethylbutanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2-isopropyl-2-methylpentanoic acid, 2-propyl-2-methylpentanoic acid 2-ethyl-2,3-dimethylpentanoic acid, 2-ethyl-2,4-dimethylpentanoic acid, 2-ethyl-2-methylhexanoic acid, 2-ethyl-
2-methylheptanoic acid, 2-ethyl-2,4,4-trimethylpentanoic acid, 2-ethyl-2,3,3-trimethylpentanoic acid, 2-ethyl-2,3,4-trimethylpentanoic acid, 2
-Ethyl-2,3-dimethylhexanoic acid, 2-ethyl-2,
4-dimethylhexanoic acid, 2-ethyl-2,5-dimethylhexanoic acid, 2-isopropyl-2,4-dimethylpentanoic acid, 2-isopropyl-2-methylhexanoic acid, 2-
Propyl-2-methylhexanoic acid, 2,2-diethylhexanoic acid, 2,2-diethyl-4-methylpentanoic acid, 2,2
-Diethyl-3-methylpentanoic acid, 2,2-diethyl-
3,3-dimethylbutanoic acid, 2-ethyl-2-propylpentanoic acid, 2-ethyl-2-isopropylpentanoic acid,
2,3-dimethyl-2-propylpentanoic acid, 2,4-dimethyl-2-propylpentanoic acid, 2-tert-butyl-2
-Methylpentanoic acid, 2-isopropyl-2,3,3-trimethylbutanoic acid, 2,2-diisopropylbutanoic acid, 2-
Ethyl-2,3,3,4-tetramethylpentanoic acid, 2-ethyl-2,3,4,4-tetramethylpentanoic acid, 2-isopropyl-2,4-dimethylhexanoic acid, 2-isopropyl-
2,3,3-trimethylpentanoic acid, 2-isopropyl-2,
4,4-trimethylpentanoic acid, 2-isopropyl-2,3,
4-trimethylpentanoic acid, 2,2-diethyl-3,3-dimethylpentanoic acid, 2,2-diethyl-4,4-dimethylpentanoic acid, 2-tert-butyl-2-ethylpentanoic acid,
2-isopropyl-2-ethyl-3-methylpentanoic acid, 2-isopropyl-2-ethyl-4-methylpentanoic acid, 2-isopropyl-2-ethyl-3,3-dimethylbutanoic acid, 2,2-diisopropylpentane Acid, 2,2-diisopropyl-3-methylbutanoic acid, 2-ethyl-2,3,
3,5-tetramethylhexanoic acid, 2-ethyl-2,3,4,4
-Tetramethylhexanoic acid, 2-ethyl-2,4,4,5-tetramethylhexanoic acid, 2-ethyl-2,3,5,5-tetramethylhexanoic acid, 2-ethyl-2,4,5, 5-tetramethylhexanoic acid, 2-isopropyl-2,3,4-trimethylhexanoic acid, 2-isopropyl-2,3,5-trimethylhexanoic acid, 2-isopropyl-2,3,3,4-tetramethylpentane Acid, 2-isopropyl-2,3,4,4-tetramethylpentanoic acid, 2-ethyl-2-isopropyl-4,4-
Dimethylpentanoic acid, 2-tert-butyl-2,4,4-trimethylpentanoic acid, 2-tert-pentyl-2,4-dimethylpentanoic acid, 2-ethyl-2-isopropyl-3,4-
Dimethylpentanoic acid, 2-isopropyl-2,3,5,5-tetramethylhexanoic acid, 2,3,4-trimethyl-2-neopentylpentanoic acid, 2,4,4-trimethyl-2-tert-
Pentylpentanoic acid, 2-ethyl-2,3,3,5,5-pentamethylhexanoic acid, 2-cyclohexyl-2,3-dimethylbutanoic acid, 2-cyclopentyl-2-ethylbutanoic acid, 2-cyclopentyl-2- Ethyl-3-methylbutanoic acid and the like, and Eacid 9 (mainly composed of 2-isopropyl-2,3-dimethylbutanoic acid and 2-ethyl-2,3,3-trimethylbutanoic acid) and Ecacid 13 (2-
Isopropyl-2,3,5,5-tetramethylhexanoic acid, 2,
3,4-trimethyl-2-neopentylpentanoic acid, 2,4,
4-trimethyl-2-tert-pentylpentanoic acid, 2-
Commercial products (manufactured by Idemitsu Petrochemical Co., Ltd.) such as ethyl-2,3,3,5,5-pentamethylhexanoic acid can also be used. In addition, examples of the carboxylic acid derivative in the present invention include lower alkyl esters of carboxylic acids, acid anhydrides, acid halides and the like as described above.

As the ester used in the present invention, a single ester or a mixture of two or more esters is used, and is usually formed by one or more of the above-mentioned alcohols and one or more of the above-mentioned carboxylic acids or one or more of their derivatives. Can be obtained by an esterification reaction or a transesterification reaction. As for the specific method, a known method can be used, and it is described in detail, for example, in New Experimental Chemistry Course 14, Synthesis and Reaction of Organic Compounds (II) ((1977) Maruzen).

Such a tertiary carboxylic acid ester in which all carbon atoms at the α-position of the carbonyl group are bonded to carbon is described in the above-mentioned JP-A-3-505602 (WO90 / 12849). This patent states that those having two methyl groups bonded to the α-position are most preferred. In the examples, esters of neo acids (manufactured by Exxon Chemical Co., Ltd.) are shown, but neoheptanoic acid manufactured by Exxon Chemical Co., Ltd. is 2,2-dimethylpentanoic acid, and neodecanoic acid is 2,2-
It is widely known that dimethyloctanoic acid is the main component.

However, such esters of tertiary carboxylic acids having two methyl groups at the α-position have a high melting point,
For use in refrigeration oils that require fluidity at low temperatures,
During the refrigeration cycle, especially at the evaporator, the ester may be undesirably separated. Therefore, in the ester used in the present invention, it is necessary that at least two of the alkyl groups R ¹ , R ² and R ³ bonded to the carbon at the α-position of the carboxylic acid have two or more carbon atoms. As such, an ester in which at least two of R ¹ , R ² , and R ³ have 2 or more carbon atoms has a low melting point, and thus is preferable.
In the ester used in the present invention, n

[0023]

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May be the same or different.

The compatibility of the ester used in the present invention with a hydrofluorocarbon-based refrigerant at a low temperature generally decreases as the viscosity increases. Therefore, a preferred ester in terms of compatibility has a kinematic viscosity at 100 ° C. of 1 cs.
t and 100 cst or less, more preferably 1
It is not less than cst and not more than 50 cst. The acid value of these esters is preferably as low as possible, usually 0.1 mgKOH / g or less,
In particular, it is preferably 0.05 mgKOH / g or less. Acid value is 0.1mg
If it is larger than KOH / g, the corrosiveness to metals may increase, which is not preferable. The hydroxyl value of these esters is usually 0.1 mgKOH / g or more and 50 mgKOH / g.
Or less, preferably 0.1 mgKOH / g or more and 30 mgKOH / g or more.
g or less. More preferably, it is 0.1 mgKOH / g or more and 20 mgKOH / g or less. If the hydroxyl value is more than 50 mgKOH / g, the hygroscopicity increases, and if it is less than 0.1 mgKOH / g, the abrasion resistance becomes poor, which is not preferable. The ester used in the present invention desirably has a low two-phase separation temperature with the hydrofluorocarbon, preferably -10 ° C or lower, more preferably -30 ° C or lower, and particularly preferably -50 ° C or lower.

The refrigerating machine oil having an ester as a base oil used in the present invention is a mineral oil, a poly-α-olefin, an alkylbenzene, an ester or a polyether other than the above, as long as the compatibility with the hydrofluorocarbon is not impaired. Synthetic oils such as polyethers and phosphates may be mixed. A working fluid composed of a composition containing a hydrofluorocarbon and the ester satisfies the object of the present invention, particularly, the hydrolysis stability.

However, the conventional working fluid CF
Compared to C12-mineral oil system, HFC134a-ester system has higher polarity for both chlorofluorocarbons and oils and easily contains water.
Although the refrigerator is equipped with a dryer that removes water by molecular sieve, the PET film, which is a green material, may be hydrolyzed by the remaining water that could not be removed sufficiently to produce carboxylic acid. is there. Therefore, to the ester used in the present invention, if necessary, water in the composition, or a compound having an epoxy group to trap the generated carboxylic acid, an orthoester or an acetal, or a carboxylic acid may be added. In order to protect the metal surface from corroding the metal, it is preferable to add benzotriazole and / or a benzotriazole derivative. Further, in order to improve lubricity, a triaryl phosphate and / or triaryl phosphite is added. In order to improve thermal stability, a phenolic compound having a radical trapping function or a metal compound having a chelating ability is used. It is also effective to add an activator. Among these additives, it is preferable to add a compound having an epoxy group, an orthoester or an acetal, and particularly preferable to add a compound having an epoxy group.

Examples of the compound having an epoxy group include phenyl glycidyl ether, butyl glycidyl ether,
Glycidyl ethers such as 2-ethyl glycidyl ether, cresyl glycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether And
Glycidyl esters such as diglycidyl phthalate, diglycidyl cyclohexanedicarboxylate and diglycidyl adipate; epoxidized fatty acid monoesters such as epoxidized methyl stearate and epoxidized butyl stearate; and epoxidized soybean oil ,
Examples include epoxidized vegetable oils such as epoxidized linseed oil, and alicyclic epoxy compounds such as epoxycyclooctane, epoxycycloheptane, a compound having an epoxycyclohexyl group, and a compound having an epoxycyclopentyl group described below.

In a system of CFC12 or monochlorodifluoromethane (HCFC22) containing a chlorine atom, since hydrochloric acid is generated by decomposition of chlorofluorocarbon, glycidyl ethers such as phenylglycidyl ether and epoxidized fatty acid monoesters are trapped. And epoxidized vegetable oils are widely added to oils such as naphthenic oils. JP
As disclosed in JP-A-57-63395, there is an example in which a compound having an epoxycycloalkyl group such as epoxycyclooctane is added to a polyether compound to prevent the polyether compound from being deteriorated by hydrochloric acid. However, the acid generated in the composition of the hydrofluorocarbon and the ester used in the present invention is not a strong acid such as hydrochloric acid, but PE.
Since it is a weak acid such as a carboxylic acid generated by hydrolysis of T film, the ordinary epoxy compound as described above is not so effective, and in the present invention, it has an alicyclic epoxy compound, particularly an epoxycyclohexyl group . Compounds and compounds having an epoxycyclopentyl group are preferred.

The compound having an epoxycyclohexyl group and the compound having an epoxycyclopentyl group used in the present invention have 5 to 40 carbon atoms, preferably 5 to 2 carbon atoms.
5, specifically 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4
-Epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, exo-2,3
-Epoxynorbornane, 2- (7-oxabicyclo [4.1.0] hept-3-yl) -spiro (1,3-dioxane-5,3 '-[7] oxabicyclo [4.1.0] heptane), 4 -Epoxyethyl-1,2-epoxycyclohexane, 4- (1'-methylepoxyethyl) -1,2-epoxy-2-methylcyclohexane and the like, although not particularly limited, preferably 1,2 -Epoxycyclohexane, 1,2-epoxycyclopentane, bis (3,
4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl)
Adipate, 3,4-epoxycyclohexylmethyl-3,
4--epoxycyclohexanecarboxylate, 2-
(7-oxabicyclo [4.1.0] hept-3-yl)-
Spiro (1,3-dioxane-5,3 '-[7] oxabicyclo [4.1.0] heptane).

In the present invention, these compounds having an epoxycyclohexyl group may be used alone or in combination of two or more, or the compounds having an epoxycyclopentyl group may be used alone or in combination of two or more. Further, a compound having an epoxycyclohexyl group and a compound having an epoxycyclopentyl group may be used in combination. The addition amount is usually 0.05 to 2.0 parts by weight, preferably 0.1 to 1.5 parts by weight, more preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the ester used in the present invention. Department.
In some cases, the compound having an epoxycyclohexyl group or the compound having an epoxycyclopentyl group may be used in combination with another epoxy compound such as glycidyl ether.

The orthoester used in the present invention has 4 to 70 carbon atoms, and more preferably has 4 carbon atoms.
~ 50. Specifically, methyl orthoformate,
Ethyl orthoformate, propyl orthoformate, isopropyl orthoformate, butyl orthoformate, isobutyl orthoformate, pentyl orthoformate, hexyl orthoformate, 2-ethylhexyl orthoformate, methyl orthoacetate, ethyl orthoacetate, propyl orthoacetate, isopropyl orthoacetate, Butyl orthoacetate, isobutyl orthoacetate, pentyl orthoacetate, hexyl orthoacetate, 2-ethylhexyl orthoacetate, methyl ortho-2-ethylhexanoate, ethyl ortho-2-ethylhexanoate, propyl ortho-2-ethylhexanoate, propyl ortho-2-ethyl Isopropyl hexanoate, butyl ortho 2-ethylhexanoate, ortho 2
-Isobutyl ethylhexanoate, pentyl ortho-2-ethylhexanoate, hexyl ortho-2-ethylhexanoate and 2-ethylhexyl ortho-2-ethylhexanoate. Here, the amount of the orthoester is usually 0.01 to 100 parts by weight per 100 parts by weight of the ester used in the present invention.
Parts by weight, preferably 0.05 to 30 parts by weight.

The acetal used in the present invention has 4 to 70 carbon atoms, more preferably 4 to 50 carbon atoms.
belongs to. Specifically, cyclohexanone ethylene ketal, cyclohexanone methyl ethylene ketal,
Cyclohexanone 2,2-dimethyltrimethylene ketal, cyclohexanone dimethyl acetal, cyclohexanone diethyl acetal, acetone ethylene ketal, acetone methyl ethylene ketal, acetone 2,2-
Dimethyl trimethylene ketal, acetone dimethyl acetal, acetone diethyl acetal, methyl ethyl ketone ethylene ketal, methyl ethyl ketone methyl ethylene ketal, methyl ethyl ketone 2,2-dimethyl trimethylene ketal, methyl ethyl ketone dimethyl acetal, methyl ethyl ketone diethyl acetal, methyl isobutyl ketone ethylene ketal, methyl isobutyl ketone methyl Ethylene ketal, methyl isobutyl ketone 2,2-dimethyl trimethylene ketal, methyl isobutyl ketone dimethyl acetal, methyl isobutyl ketone diethyl acetal, diisopropyl ketone ethylene ketal, diisopropyl ketone methyl ethylene ketal, diisopropyl ketone 2,2-dimethyl trimethylene ketal, diisopro Le ketone dimethyl acetal,
Diisopropyl ketone diethyl acetal, benzaldehyde ethylene ketal, benzaldehyde methyl ethylene ketal, benzaldehyde 2,2-dimethyltrimethylene ketal, benzaldehyde dimethyl acetal, and benzaldehyde diethyl acetal. Here, the amount of the acetal to be added is usually 0.01 to 100 parts by weight, preferably 0.05 to 30 parts by weight, based on 100 parts by weight of the ester used in the present invention.

Benzotriazole used in the present invention,
The benzotriazole derivative has 6 to 50 carbon atoms, preferably 6 to 30 carbon atoms. Specifically, benzotriazole, 5-methyl-1H-benzotriazole, 1-dioctylaminomethylbenzotriazole, 1-dioctylaminomethyl-5-methylbenzotriazole, 2- (5′-methyl-2′-hydroxy Phenyl) benzotriazole, 2- [2′-hydroxy-3 ′,
5'-bis (α, α-dimethylbenzyl) phenyl] -2
H-benzotriazole, 2- (3 ′, 5′-di-tert-butyl-2′-hydroxyphenyl) benzotriazole,
2- (3'-t-butyl-5'-methyl-2'-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3 ',
5'-di-t-butyl-2'-hydroxyphenyl) -5
-Chlorobenzotriazole, 2- (3 ', 5'-di-t-
Amyl-2'-hydroxyphenyl) benzotriazole, 2- (5'-t-butyl-2'-hydroxyphenyl)
Benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole,
2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole and the like, preferably benzotriazole, 5- And methyl-1H-benzotriazole. Here, the amount of benzotriazole and / or benzotriazole derivative added depends on the amount of the ester 1 used in the present invention.
It is usually 0.001 to 0.1 part by weight, preferably 0.003 to 0.03 part by weight, based on 00 parts by weight.

The triaryl phosphate or triaryl phosphite used in the present invention has 18 carbon atoms.
To 70, more preferably 18 to 50 carbon atoms.
belongs to. Specifically, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, tris (tribromophenyl) phosphate, tris (dibromophenyl) phosphate Triaryl phosphates such as phosphate, tris (2,4-di-t-butylphenyl) phosphate and trinonyl phenyl phosphate, triphenyl phosphite, tricresyl phosphite, trixylenyl phosphite, cresyl Diphenyl phosphite, xylenyl diphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, trinonyl phenyl phosphite, tris (tribromophenyl) phosphite, Squirrel include triaryl phosphite such as (dibromophenyl) phosphite, preferred are triphenyl Fe -
, Tricresyl phosphate, trixylenyl phosphate, tris (2,4-di-t-butylphenyl) phosphate, triphenyl phosphite, tricresyl phosphite, trixylenyl phosphite, tris (2 , 4-di-t-butylphenyl) phosphite. Here, the amount of the triaryl phosphate and / or triaryl phosphite added is
Usually 0.1 to 100 parts by weight of the ester used in the present invention.
To 5.0 parts by weight, preferably 0.5 to 2.0 parts by weight.

The phenolic compound having a radical trapping function used in the present invention has 6 to 100 carbon atoms, preferably 10 to 80 carbon atoms. In particular,
2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4,4′-methylenebis (2,6
-Di-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4′-isopropylidenebisphenol, 2,4-dimethyl-6-t-butylphenol, tetrakis [methylene-3- (3,5-di-t-butyl- 4 −
Hydroxyphenyl) propionate] methane, 1,1,3
-Tris (2-methane-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) ) Benzene, 2,2′-dihydroxy-3,3′-di (α-methylcyclohexyl) -5,5′-dimethyl-diphenylmethane, 2,2′-isobutylidenebis (4,6-dimethylphenol), Bis [3,3-bis- (4′-hydroxy-3′-
t-butylphenyl) butyric acid glycol ester, 2,6-bis (2'-hydroxy-3'-t-butyl-5'-methylbenzyl) -4-methylphenol, 1,1 '
-Bis (4-hydroxyphenyl) cyclohexane, 2,
5-di-t-amylhydroquinone, 2,5-di-t-butylhydroquinone, 1,4-dihydroxyanthraquinone,
3-tert-butyl-4-hydroxyanisole, 2-tert-
Butyl-4-hydroxyanisole, 2,4-dibenzoylresorcinol, 4-tert-butylcatechol, 2,6-
Di-t-butyl-4-ethylphenol, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,4,5-trihydroxybenzophenone, α -Tocopherol, bis [2- (2-hydroxy-5-methyl-3-t-butylbenzyl) -4-methyl-6-t-butylphenyl] terephthalate, triethylene glycol-bis [3- (3-t- Butyl-5-methyl-4-hydroxyphenyl) propionate], 1,
6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,
9-bis [2- (3-tert-butyl-4-hydroxy-5
-Methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane and the like, preferably 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4,4′-methylenebis (2,6-di-t-butylphenol), 4,4′-butylidenebis (3-methyl-6
-T-butylphenol), 2,2'-methylenebis (4-
Ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4 '
-Isopropylidene bisphenol, 2,4-dimethyl-6
-T-butylphenol, tetrakis [methylene-3
-(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane,
1,3,5-trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene, 2,6-di-t-butyl-4-ethylphenol, 2,6-bis (2 ′
-Hydroxy-3'-t-butyl-5'-methylbenzyl)
4-methylphenol, bis [2- (2-hydroxy-5-methyl-3-tert-butylbenzyl) -4-methyl-6-tert-butylphenyl] terephthalate, triethylene glycol-bis [3- (3 -T-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,
6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]. Here, the addition amount of the phenolic compound is usually 0.05 to 2.0 parts by weight per 100 parts by weight of the ester used in the present invention.
Parts by weight, preferably 0.05 to 0.5 parts by weight.

The metal deactivator used in the present invention preferably has chelating ability and has 5 to 50 carbon atoms, preferably 5 to 20 carbon atoms. Specifically, N, N '
-Disalicylidene-1,2-diaminoethane, N, N'-disalicylidene-1,2-diaminopropane, N-salicylidene-N'-dimethyl-1,2-diaminoethane, N, N'-
Disalicylidenehydrazine, N, N'-bis (α, 5-dimethylsalicylidene) -1,2-diaminoethane, N, N'-bis (α, 5-dimethylsalicylidene) -1,3 -Propanediamine, N, N'-bis (α, 5-dimethylsalicylidene)-
1,6-hexanediamine, N, N′-bis (α, 5-dimethylsalicylidene) -1,10-decanediamine, N, N′-bis (α, 5-dimethylsalicylidene) ethylenetetratra Amine, salicylaldoxime, 2-hydroxy-5-methylacetophenoxime, acetylacetone, ethyl acetoacetate, 2-ethylhexyl acetoacetate, dimethyl malonate, diethyl malonate, di-2-ethylhexyl malonate, anthranilic acid, nitronitriacetic acid Dihydroxyethylglycine, hydroxyethylethylenediaminetriacetic acid, hydroxyethyliminodiacetic acid, ethylenediamine, 3-mercapto-1,2-propanediol, alizarin, quinizarin, mercaptobenzothiazole and the like, and preferably N, N′-disalicylidene. -1,2-Diaminoethane, N, N'-disalicylidene 1,2 - diaminopropane, acetylacetone, ethyl acetoacetate, acetoacetate 2 - ethylhexyl, alizarin, a quinizarin like. Here, the addition amount of the metal deactivator is usually 0.001 to 100 parts by weight of the ester used in the present invention.
2.0 parts by weight, preferably 0.003 to 0.5 part by weight.

If necessary, other lubricating oil additives such as antioxidants, extreme pressure agents, oiliness improvers, defoamers and the like other than those described above can also be added. For example, those that can be used as antioxidants include p, p-dioctylphenylamine, monooctyldiphenylamine, phenothiazine, 3,7-dioctylphenothiazine, phenyl-1-naphthylamine, phenyl-2-naphthylamine, and alkylphenyl-1-. Amine antioxidants such as naphthylamine and alkylphenyl-2-naphthylamine; sulfur antioxidants such as alkyl disulfide, thiodipropionate and benzothiazole; zinc dialkyldithiophosphate and zinc diaryldithiophosphate. . The addition amount is 0.05 to 2.0 parts by weight based on 100 parts by weight of the ester.

Examples of usable extreme pressure agents and oiliness improvers include zinc compounds such as zinc dialkyldithiophosphate and zinc diaryldithiophosphate, thiodipropionate, dialkylsulfide, dibenzylsulfide, dialkylpolysulfide, and alkyl. Sulfur compounds such as mercaptan, dibenzothiophene and 2,2'-dithiobis (benzothiazole), phosphorus compounds such as trialkyl phosphite and trialkyl phosphate,
Chlorinated compounds such as chlorinated paraffins, molybdenum compounds such as molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum disulfide, perfluoroalkylpolyethers, fluorinated compounds such as trifluorinated ethylene chloride polymer, graphite fluoride, and fatty acid modified Silicon compounds such as silicone, graphite and the like. The addition amount is 0.05 to 10 parts by weight based on 100 parts by weight of the ester used in the present invention.
Parts by weight.

Those used as antifoaming agents include silicone oils such as dimethylpolysiloxane, and organosilicates such as diethyl silicate. The amount added
0.000 to 100 parts by weight of the ester used in the present invention
It is 5 to 1 part by weight. Further, an additive such as an organic tin compound or a boron compound for stabilizing the CFC refrigerant may be added.
The amount of addition was 0.001 to 100 parts by weight of the ester.
To 10 parts by weight.

The composition for a working fluid of a refrigerator according to the present invention is obtained by blending a hydrofluorocarbon and an ester used in the present invention or an oil obtained by adding the above-mentioned additive to the ester used in the present invention by a conventional method. It can be easily prepared. The compounding ratio is usually hydrofluorocarbon / oil = 5/1 to 1/10 (weight ratio), preferably 2/1 to 1/5 (weight ratio).

The hydrofluorocarbon used in the present invention includes difluoromethane (HFC32), 1,1-difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFC143a), 1,1,1,2-tetrafluoromethane. Fluoroethane (HFC1
34a), 1,1,2,2-tetrafluoroethane (HFC134),
Pentafluoroethane (HFC125) etc., especially 1,1,1,
2-Tetrafluoroethane is preferred.

[0043]

EXAMPLES The present invention will now be described specifically with reference to test examples, but the present invention is not limited thereto. In the test examples, the esters A and B used for the product of the present invention synthesized according to the following production examples and the esters a to d used for the comparative product were used.

Production Example 1 A 2-liter four-necked flask was equipped with a stirrer, thermometer, dropping funnel and cooler. Equacid 9 (2-
Isopropyl-2,3-dimethylbutanoic acid, 2-ethyl-
361 g (2.25 mol) of 2,3,3-trimethylbutanoic acid as a main component (manufactured by Idemitsu Petrochemical Co., Ltd.) is placed in the above flask, and 375 g (3.15 mol) of thionyl chloride is dropped from the dropping funnel at 80 ° C. for 3 hours. And dropped. Furthermore, at 80 ° C, 1
After aging for 30 minutes, the acid chloride of equacid 9 was obtained by distillation. Next, 38.5 g (0.37 mol) of neopentyl glycol and 128.8 g (1.63 mol) of pyridine were placed in a 500 ml four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser. The above acid chloride 1
45.6 g (0.81 mol) was added dropwise from the dropping funnel at room temperature in 10 minutes. The temperature was further raised to 110 ° C. and the reaction was carried out for 4 hours. Then, after cooling to room temperature, hexane 200 ml
50 ml of water was added, the layers were separated, and the hexane layer was washed three times with a 10% aqueous sulfuric acid solution and once with a saturated aqueous sodium hydrogen carbonate solution. After removing hexane with a rotary evaporator, the residue was distilled to obtain ester A used in the present invention.

Production Example 2 As in Production Example 1, 29.5 g (0.22 mol) of trimethylolpropane and pyridine 1 were placed in a 500 ml four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser.
Take 44.3 g (1.32 mol) and add Equad 9
129.8 g (0.73 mol) of the acid chloride was added dropwise from a dropping funnel at room temperature for 10 minutes. Further, the temperature was raised to 110 ° C., and the reaction was further performed for 4 hours. Then, after cooling to room temperature, 200 ml of hexane and 50 ml of water were added, and the layers were separated.
The hexane layer was washed three times with a 10% aqueous sulfuric acid solution and once with a saturated aqueous sodium hydrogen carbonate solution. After removing hexane with a rotary evaporator, the low-boiling substances were further removed by distillation to obtain ester B used in the present invention.

Production Example 3 29.5 g (0.22 mol) of trimethylolpropane and pyridine 1 were prepared in the same flask as in Production Example 2 by the same method.
44.3 g (1.32 mol) and pivalic acid chloride 87.5
The ester a was obtained from g (0.73 mol).

Production Example 4 A 1-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydrating tube with a condenser. 67 g (0.50 mol) of trimethylolpropane and 426 g (1.50 mol) of 2,2-dimethylhexadecanoic acid were placed in the flask, reacted at 250 ° C. under normal pressure at 250 ° C. for 2 hours, and then depressurized at 150 Torr for 30 hours. The reaction was performed. Thereafter, unreacted monocarboxylic acid was removed by distillation under reduced pressure to obtain ester b.

Production Example 5 In a flask similar to that of Production Example 4, 134 g (1.00 mol) of trimethylolpropane and 110.2-methylhexanoic acid were added.
2 g (0.85 mol), 44.1 g of 2-ethylpentanoic acid
(0.34 mol) and 3,5,5-trimethylhexanoic acid 28
Take 6.5 g (1.81 mol) under nitrogen atmosphere at normal pressure.
After reacting at 0 ° C. for 2 hours, a reduced pressure reaction was performed at 150 Torr for 6 hours. Thereafter, unreacted monocarboxylic acid was removed by distillation under reduced pressure to obtain ester c.

Production Example 6 Pentaerythritol 1 was placed in the same flask as in Production Example 4.
36 g (1.00 mol), 32-methylhexanoic acid 324.7
g (2.50 mol) and 216.4 g of 2-ethylhexanoic acid
(1.50 mol) was obtained, and ester d was obtained in the same manner as in Production Example 5.

Test Example 1 The kinematic viscosities at 40 ° C. and 100 ° C. of the esters A and B used in the present invention and the esters ad used for the comparative products (JIS
K-2283), melting point, and two-phase separation temperature at a low temperature at a sample concentration of 10 vol% with respect to 1,1,1,2-tetrafluoroethane. Table 1 shows the results.

[0051]

[Table 1]

As shown in Table 1, esters of tertiary carboxylic acids having two methyl groups at the α-position of the carbonyl group (esters a and b used as comparative products) have at most one ester at the α-position of the carbonyl group. Compared to tertiary carboxylic acid esters having only a methyl group (esters A and B used in the present invention),
High melting point. Further, the esters A and B used in the present invention are:
It has a low two-phase separation temperature and is sufficiently excellent in compatibility with 1,1,1,2-tetrafluoroethane.

Test Example 2 Ester A or B obtained in Production Examples 1 and 2 was combined with 1,1,1,
A shield tube test was conducted under the following conditions to examine the hydrolytic stability of the composition for a working fluid of a refrigerator of the present invention (products A and B of the present invention) obtained by blending 2-tetrafluoroethane (HFC134a). went. That is,
In advance, make the water concentration 3000 ppm or less and the acid value 0.01 (mgKO
H / g) 10 g of the ester A or B prepared below and 5 g of HFC134a were placed in a glass tube, and iron,
Copper and aluminum were added and the tube was sealed. After testing at 175 ° C. for 14 days, the sealed tube was opened, HFC134a was removed, and the acid value of each ester was determined. Table 2 shows the results.

Test Example 3 The ester c or d obtained in Production Examples 5 and 6 was combined with 1,1,1,
For the comparative products c and d obtained by blending 2-tetrafluoroethane (HFC134a), a shield tube test was conducted in the same manner as in Test Example 2 to examine the hydrolysis stability, and the acid value of each ester was examined. Table 2 shows the results.

[0055]

[Table 2]

As is clear from Table 2, the products A and B of the present invention using an ester of a tertiary carboxylic acid having at most one methyl group at the α-position of the carbonyl group have hydrogen at the α-position of the carbonyl group. The acid value of the ester after the test is lower than that of the comparative products c and d using an ester of a carboxylic acid which is not a tertiary carboxylic acid having an atom, and the hydrolysis stability is excellent.

[0057]

The composition for a working fluid of a refrigerator according to the present invention, which contains an ester and a hydrofluorocarbon, is excellent in compatibility and thermal stability, and particularly excellent in hydrolysis stability. is there.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI C10N 30:08 40:30 (58) Investigated field (Int.Cl. ⁶ , DB name) C10M 105/38 C10M 129/18 C10N 40:30 CA (STN)

Claims (1)

(57) [Claims] 1. A refrigerating machine oil comprising an ester represented by the general formula (I) as a base oil , a hydrofluorocarbon ,
Compound having epoxyoxyhexyl group and epoxy
Selected from the group consisting of compounds having a clopentyl group
A composition for a working fluid of a refrigerator comprising at least one kind . Embedded image (Wherein, R ¹ is an alkyl group having 1 to 9 carbon atoms, R ² ,
R ³ represents an alkyl group having 2 to 10 carbon atoms. R ¹ ,
R ² and R ³ may be the same or different, and R ¹ , R ² ,
The total number of carbon atoms of R ³ is 5 or more and 13 or less. R
⁴ represents an n-valent alcohol residue having 2 to 30 carbon atoms. n is an integer of 2 to 6, and n May be the same or different. )