JPH05163499A - Composition for working fluid of refrigerating machine - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent compatibility, thermal stability and hydrolytic resistance by adding a hydrofluorocarbon to an oil for refrigerator comprising a cyclic compound which has a substituent group containing a ketone group in the molecule and may contain O in the ring as a base oil. CONSTITUTION:An oil for refrigerating machine comprising a monocyclic or dicyclic compound (e.g. 1-acetyl-4-dodecylbenzene) which is shown by the formula (X is monocyclic or dicyclic compound which may contain oxygen in the ring; R1 is substituent group containing at least one ketone group in the molecule; R2 is substituent group containing at least one ether group in the molecule; (m) is 1-20 integer; (n) is 0-20 integer), has a substituent group containing at least one ketone group 111 the molecule and may contain oxygen in the ring as a base oil is blended with a hydrofluorocarbon (e.g. 1,1,1,2-tetrafluoroethane) to give the objective composition for working fluid of refrigerating machine having excellent compatibility and thermal stability and low moisture absorption free from fear of hydrolysis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working fluid composition for refrigerators, and more particularly to a working fluid composition for compression refrigerators such as electric refrigerators.

[0002]

2. Description of the Related Art Recently, the problems to be solved by the invention
The use of dichlorodifluoromethane (CFC12), which is used in refrigerators and car coolers to protect the ozone layer, has been regulated and is being banned in the future. Therefore, as a substitute for this CFC12, hydrofluorocarbon (HFC) that does not destroy the ozone layer has been developed. However, since hydrofluorocarbon has a higher polarity than CFC12, naphthene-based mineral oil or poly-α- which has been generally used as a refrigerating machine oil has been used.
When using lubricating oils such as olefins and alkylbenzenes,
The compatibility between these lubricating oils and hydrofluorocarbons is poor, and two-layer separation occurs at low temperatures. When two-layer separation occurs, oil return deteriorates and a thick oil film adheres to the vicinity of the condenser or evaporator as a heat exchanger to hinder heat transfer, and it is important that lubrication failure and foaming at startup occur. Cause defects. Therefore, the conventional refrigerating machine oil cannot be used as the refrigerating machine oil under these new refrigerant atmospheres.

Regarding lubricity, in CFC12, it is partially decomposed to generate hydrogen chloride, and this hydrogen chloride reacts with the friction surface to form a chloride film to improve lubricity. was there. However, since such effects cannot be expected for hydrofluorocarbons containing no chlorine atom, refrigerating machine oils used with hydrofluorocarbons are required to have better lubricity than conventional ones. Further, the refrigerating machine oil used together with hydrofluorocarbon must have good thermal stability in the coexistence with hydrofluorocarbon. Further, in addition to this, since the compression refrigerator of the electric refrigerator has an organic material used for a motor such as an insulating material and an enameled wire, the working fluid composed of hydrofluorocarbon and refrigerating machine oil contains these organic materials. It is necessary that the material is not adversely affected and that the electrical insulation is good.

Hydrofluorocarbons, eg 1,
1,1,2-Tetrafluoroethane (HFC134a)
Examples of refrigerating machine oils that can be used together with US Pat. No. 4,755,316, JP-A-1-198694, JP-A-1-256594, and JP-A 1-25.
No. 9093, No. 1-259094, No. 1-259095, No. 2-84491, No. 2-102296, No. 2-129.
No. 294, No. 2-132176, No. 2-132177, No. 2-132178, No. 2-132179, No. 2-173.
195, JP-A-2-180986, JP-A-2-180987, JP-A-2-182780, JP-A-2-242823, and JP-A-2-242.
No. 888, No. 2-258896, No. 2-269195, No. 2-276880, No. 2-27681, and No. 2-272.
097, JP-A-2-281098, JP-A-2-305893, JP-A-3-14894, JP-A-3-28296, and JP-A-3-3319.
No. 2, JP-A-3-33193, etc. disclose polyether compounds.

Since the polyether compound has a higher polarity than naphthenic mineral oil, the compatibility with HFC134a at low temperature is certainly good. However, US Pat.
As described in Japanese Patent No. 55316, on the contrary, the polyether compound has a problem that two-phase separation occurs when the temperature rises. Further, the polyether compound has some other problems. One is that it has poor electrical insulation. This is a very big problem and cannot be used in refrigerators for electric refrigerators. Another problem is that it is highly hygroscopic. Due to the water content in the polyether compound, the thermal stability in the coexistence of HFC134a is deteriorated, and the PET film or the like which is an organic material is hydrolyzed.

Ester compounds have been developed in order to improve the problems of the polyether compounds such as the electric insulating property and the hygroscopic property. For example, as a refrigerating machine oil that can be used with 1,1,1,2-tetrafluoroethane (HFC134a), U.S. Pat. No. 4,851,144.
Specification (JP-A-2-276894) and JP-A-2
-158693 discloses a mixed oil of a polyether oil and an ester oil, and US Pat. No. 2,261,541 and European Patent 406,479 disclose the ester oil.

The ester compound is excellent in compatibility with hydrofluorocarbon and also excellent in thermal stability in the presence of hydrofluorocarbon. In addition, it has extremely excellent electrical insulation properties and considerably low hygroscopicity as compared with polyether compounds. However, compared with the CFC12-mineral oil system, which is a conventional working fluid, in the hydrofluorocarbon-ester oil system, both CFC12 and oil have higher polarities and are likely to contain water. Therefore, there is a problem that ester oil is hydrolyzed to generate carboxylic acid, and the generated carboxylic acid corrodes a metal to cause abrasion.

As described above, the hydrofluorocarbon-polyether oil system which has been developed so far has a problem of hygroscopicity and electric insulation, and the hydrofluorocarbon-ester oil system has a problem of hydrolysis resistance, and the conventional CFC12-mineral is problematic. Compared to an oil system, it tends to contain water, which causes deterioration of thermal stability, deterioration of organic materials, corrosion and wear of metals, etc., and is not satisfactory as a working fluid for a refrigerator. Therefore, an object of the present invention is to provide a composition for a refrigerator working fluid that does not have the above problems.

[0009]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventor has found that oxygen is introduced into the ring having a substituent containing at least one ketone group in the molecule. It was found that the above object can be achieved by using a refrigerating machine oil containing a monocyclic or bicyclic cyclic compound which may be contained as a base oil, and the present invention has been completed. That is, the gist of the present invention is: (1) A refrigerating machine oil containing a compound represented by the general formula (I) as a base oil, and a composition for a refrigerating machine working fluid containing hydrofluorocarbon.

[0010]

[Chemical 2]

(Wherein X represents a monocyclic or bicyclic cyclic compound which may contain oxygen in the ring. R ₁ represents a substituent containing at least one ketone group in the molecule. ,
R ₂ represents a substituent containing at least one ether group in the molecule. m is an integer of 1 to 20, and n is an integer of 0 to 20. However, when m is 2 or more, each R ₁ may be the same or different, and when n is 2 or more, each R _{2 is}
May be the same or different. (2) In the compound represented by general formula (I), n is an integer of 1 to 20, wherein the composition for a working fluid of a refrigerator is (3) hydrofluorocarbon is tetrafluoroethane. The composition for a working fluid for a refrigerator according to (1) or (2) above.

Examples of the monocyclic or bicyclic cyclic compound which may contain oxygen in the ring represented by X in the general formula (I) include aromatic hydrocarbons such as benzene, biphenyl and naphthalene, furan and pyran. And the like, and compounds obtained by hydrogenating these. These compounds may be substituted with an alkyl group having a linear or branched structure.

The substituent containing at least one ketone group in the molecule represented by R ₁ in the general formula (I) is a straight-chain or branched structure such as acetyl group, propionyl group, butyryl group or octanoyl group. Having an aromatic acyl group such as benzoyl group, toluoyl group, ketoacyl group such as ketopropionyl group, ketobutyryl group, acylalkyl group such as acetylmethyl group, isobutyrylethyl group, benzoylmethyl group, acetyl Acyl alkyloxy groups such as methoxy group, isobutyryl ethoxy group, acetylphenoxy group, or alkyloxyacyl groups such as acylaryl group, methoxyacetyl group, ethoxypropanoyl group, phenoxyacetyl group, or aryloxyacyl group be able to.

The substituent containing at least one ether group in the molecule represented by R ₂ in the general formula (I) is an alkyloxy group such as a methoxy group, an ethoxy group or a phenoxy group, an aryloxy group or a methoxy group. Examples thereof include an alkyloxyalkyl group such as a methyl group, an isopropoxyethyl group and a phenoxymethyl group, or an aryloxyalkyl group.

In the general formula (I), m is an integer of 1 to 20 and n is an integer of 0 to 20. Preferably m is 1
Is an integer of 4, and n is an integer of 1 to 4. m and n are 2
If it exceeds 0, the fluidity at low temperature becomes insufficient. Further, when n is 0, that is, when there is no substituent containing at least one ether group in the molecule, the compatibility with the hydrofluorocarbon becomes insufficient. Therefore, n is preferably 1 or more. Is mentioned. When m and n are 2 or more, a plurality of R ₁ and R ₂ may be the same or different.

Examples of the compound represented by the general formula (I) include various compounds, and are not particularly limited. Specifically, for example, 1-acetyl-4-dodecylbenzene (soft alkyl type), 1- (2-ethylhexanoyl) -4-isopropylbenzene, 1-
Acetyl-3-methoxybenzene, 4-ethoxy-1-
(2-ethylhexanoyl) benzene, 1- (2-ethylhexanoyl) -3,4-dimethoxybenzene, 3,
4-dimethoxyphenylacetone, 4-isoamyl-1
-(Β-ketobutyryl) benzene, 4-methoxy-1-
Methoxyacetyl-2-methylbenzene, 1-acetylmethoxy-2-methoxybenzene, 3-acetyl-2,
Examples thereof include 5-dimethylfuran and 1-acetyl-2-methoxycyclohexane. As a method of obtaining these compounds, a known method can be used, for example, a method of reacting an aromatic compound such as benzene with an acid chloride such as acetic acid chloride using a Lewis acid such as anhydrous aluminum chloride as a catalyst, or A method in which a glycidic acid ester such as methyl 2,3-epoxy-2-methyl-3- (2-methoxyphenyl) propionate is hydrolyzed and then thermally decomposed can be used.

The monocyclic or bicyclic cyclic compound which may contain oxygen in the ring having a substituent containing at least one ketone group in the molecule has a viscosity at 100 ° C. It is preferably 0.5 to 100 cst, more preferably 0.5 to 30 cst. Viscosity at 100 ° C is 1
If it exceeds 00 cst, the compatibility between this compound and hydrofluorocarbon becomes poor. The viscosity at 40 ° C is preferably 1 to 10,000 cst, more preferably 1 to 1,000 cst. Further, among those having a viscosity at 100 ° C. of 0.5 to 100 cst, it is desirable that the two-layer separation temperature at low temperature with hydrofluorocarbon is low, and the temperature is 0 ° C. or less, more preferably −10 ° C. or less. The monocyclic or bicyclic cyclic compound which may contain oxygen in the ring having a substituent containing at least one ketone group in the molecule used in the present invention has compatibility with a hydrofluorocarbon. Synthetic oils such as mineral oils, poly α-olefins, alkylbenzenes, esters, polyethers, perfluoropolyethers, and phosphoric acid esters may be mixed as long as they are not impaired.

Further, a refrigerating machine oil having a monocyclic or bicyclic cyclic compound which may contain an oxygen atom having a substituent containing at least one ketone group in the molecule as a base oil in the present invention is If necessary, an additive such as a compound having an epoxy group or an orthoester or acetal for trapping water or an acid in the composition is added, or a triaryl phosphate and / or / for improving lubricity. Or triaryl phosphite and / or trialkyl phosphate and / or trialkyl phosphite, alkyl and / or aryl dithiophosphate zinc, molybdenum dithiophosphate, molybdenum dithiocarbamate, etc. antiwear agent, tartaric acid ester, glyceryl ether, glyceryl ester Add a compound that has two hydroxyl groups at adjacent positions such as Or, a phenolic compound or aromatic amine compound having a radical trapping ability may be added to improve thermal stability.

Examples of the compound having an epoxy group used here include a glycidyl ether compound and an alicyclic epoxy compound, and a compound having an epoxycyclohexyl group or an epoxycyclopentyl group is particularly preferable. The epoxy compound used in the present invention has 5 to 60 carbon atoms, preferably 5 to 40 carbon atoms. The amount added is 100 parts by weight of the base oil used in the present invention,
0.05-5.0 parts by weight, preferably 0.05-
2.0 parts by weight.

The orthoester or acetal used in the present invention has a carbon number of 3 to 75, and its addition amount is 0.01 to 100 parts by weight with respect to 100 parts by weight of the base oil. The antiwear agent used in the present invention has 3 to 70 carbon atoms, and its addition amount is 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the base oil. The compound having two hydroxyl groups at adjacent positions used in the present invention has 6 to 75 carbon atoms, and the addition amount thereof is 0.01 to 100 parts by weight with respect to 100 parts by weight of base oil. The phenolic compound or aromatic amine compound used in the present invention has a radical trapping ability and has 6 to 100 carbon atoms. The amount added is 0.05 to 2.0 parts by weight with respect to 100 parts by weight of the base oil.

The composition for a refrigerator working fluid of the present invention may contain a hydrofluorocarbon and an oxygen atom having a substituent containing at least one ketone group in the molecule used in the present invention. The mixing ratio of the refrigerating machine oil having a cyclic or bicyclic cyclic compound as a base oil or the refrigerating machine oil obtained by adding an additive to the base oil is usually hydrofluorocarbon / oil = 5/1 to 1/10 (weight ratio ), Preferably 2/1 to 1/5 (weight ratio).

Hydrofluorocarbons used in the present invention include difluoromethane (HFC32), 1,1-
Difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFCl43a), 1,1,1,2
-Tetrafluoroethane (HFCl34a), 1,1,
2,2-tetrafluoroethane (HFCl34), pentafluoroethane (HFCl25) and the like, particularly 1,
1,1,2-Tetrafluoroethane is preferred.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Oils 1 to 11 used in the products of the present invention and oils 1 and 2 used in the comparative products shown in Tables 1 and 2 and 1,1,1,2-tetrafluoroethane (HFCl34a), respectively. Inventive products 1 to 11 and comparative products 1 and 2 which are compositions were prepared, and the compatibility of these was investigated. That is, the low temperature two-phase separation temperature was measured at each oil concentration of 10% by volume with respect to 1,1,1,2-tetrafluoroethane. The results are shown in Table 1 and Table 2.
Shown in. As is clear from Tables 1 and 2, the products of the present invention were more compatible than the comparative products. Table 3 shows the compound names of oils 1 to 11 used in the products of the present invention.

Example 2 In order to examine the thermal stability of the products 1 to 11 of the present invention and the comparative products 1 and 2, a shield tube test was conducted. That is, 10 g of oil and 5 g of HFC134a were taken in a glass tube, and iron, copper, and aluminum were added as a catalyst to seal the tube. 1 at 175 ° C
After testing for 4 days, the appearance of the composition of HFC134a and oil and the presence or absence of deposits were examined. The results are shown in Tables 1 and 2. As is clear from Tables 1 and 2, the products of the present invention had good appearance, no precipitates, and good thermal stability.

Example 3 In order to investigate the thermal stability in the presence of water, the products of the present invention 1 to
11 and Comparative Products 1 and 2 were subjected to a shield tube test as shown below. That is, oil 10 in the glass tube.
g, HFC134a5g, water to oil 300
0 ppm was added, and iron, copper, and aluminum were added as a catalyst, and the tube was sealed. After testing at 175 ° C. for 14 days, the sealed tube was opened, and the acid value of the oil after removing freon was examined. The results are shown in Tables 1 and 2. As is clear from Table 1 and Table 2,
None of the products of the present invention showed an increase in acid value as in Comparative product 2.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

EFFECTS OF THE INVENTION A refrigerating machine oil comprising a monocyclic or bicyclic cyclic compound which may contain oxygen in the ring having a substituent containing at least one ketone group in the molecule,
The composition for a working fluid for a refrigerator containing hydrofluorocarbon is excellent in compatibility and thermal stability, has no fear of hydrolyzability, and has low hygroscopicity.

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Claims (3)

[Claims] 1. A refrigerating machine working fluid composition comprising a refrigerating machine oil comprising a compound represented by the general formula (I) as a base oil, and hydrofluorocarbon. [Chemical 1] (In the formula, X represents a monocyclic or bicyclic cyclic compound which may contain oxygen in the ring. R ₁ represents a substituent containing at least one ketone group in the molecule, and R ₂ Represents a substituent containing at least one ether group in the molecule, m represents an integer of 1 to 20, and n represents an integer of 0 to 20.
However, when m is 2 or more, each R ₁ may be the same or different, and when n is 2 or more, each R ₂ may be the same or different. ) 2. The composition for a refrigerator working fluid according to claim 1, wherein in the compound represented by the general formula (I), n is an integer of 1 to 20. 3. The composition for refrigerator working fluid according to claim 1, wherein the hydrofluorocarbon is tetrafluoroethane.