WO2021025152A1

WO2021025152A1 - Working medium for refrigerant compression-type refrigeration cycle device, and refrigeration cycle device using said working medium

Info

Publication number: WO2021025152A1
Application number: PCT/JP2020/030409
Authority: WO
Inventors: 不二夫高橋; 康二久保; 学石塚; 達彦坂田
Original assignee: 青木油脂工業株式会社
Priority date: 2019-08-07
Filing date: 2020-08-07
Publication date: 2021-02-11
Also published as: JPWO2021025152A1; CN114174483B; CN114174483A

Abstract

[Problem] To provide a working medium for a refrigerant compression-type refrigeration cycle device, said working medium comprising a hydrocarbon-containing refrigerant and a refrigerating machine oil, wherein the refrigerating machine oil achieves at least one of the following advantages, i.e., appropriate compatibility with the refrigerant, low viscosity and high heat stability. [Solution] A working medium for a refrigerant compression-type refrigeration cycle device, said working medium comprising a refrigerant which contains a hydrocarbon having 1-8 carbon atoms and a refrigerating machine oil containing a polyalkylene glycol which is represented by general formula (1): R¹-(OR²)_n-OH [where: R¹ represents a straight chain or branched alkyl group having 1-8 carbon atoms; OR²'s are the same or different and represent an oxyalkylene group having 2 and/or 3 carbon atoms; and n represents the addition mole number of the oxyalkylene group represented by OR²] and which has an average molecular weight of 200-1000. In general formula (1), OR² includes an oxypropylene group, the ratio of the oxypropylene group is 80 mol% or more relative to the total addition mole number of OR², and the content of an alkylene glycol of general formula (1), in which n is 1, is 3 mass% or less relative to the total mass of the polyalkylene glycol.

Description

Working medium for refrigerant compression type refrigeration cycle device and refrigeration cycle device using the working medium

The present invention relates to a working medium for a refrigerant compression type refrigerating cycle device and a refrigerating cycle device using the working medium. More specifically, the present invention relates to a working medium for a refrigerant compression type refrigerating cycle device containing a refrigerant and a refrigerating machine oil, and a refrigerating cycle device using the working medium.

Hydrofluorocarbons (HFCs), which are hydrocarbons containing fluorine atoms, are used as refrigerants in refrigerating cycle devices such as air conditioners, electric refrigerators, refrigerated or frozen warehouses, and showcases that compress and use refrigerants. However, since this HFC has a long life in the atmosphere, it has a large greenhouse effect, and it is not a satisfactory refrigerant for preventing global warming, and its use is being restricted.

Instead of the above HFC, a hydrocarbon that is highly flammable but has a zero ozone depletion potential and a much smaller global warming potential than HFCs and does not contain halogen atoms (hereinafter, simply "hydrocarbon refrigerant") Also referred to as) has been proposed to be used as a refrigerant in refrigeration cycle equipment. For example, a refrigerator using a hydrocarbon containing no halogen atom as a refrigerant has been put into practical use. Further, the development of a large refrigeration cycle device using a hydrocarbon containing no halogen atom as a refrigerant is being studied. In particular, an electric refrigerator using isobutane (R600a) as a hydrocarbon refrigerant has been put into practical use, and an air conditioner using propane (R290) as a hydrocarbon refrigerant is being put into practical use. When these hydrocarbon refrigerants are used, mineral oil, alkylbenzene and polyol ester have been proposed as refrigerating machine oils used as a working medium component together with the hydrocarbon refrigerant (for example, Patent Document 1 and Patent Document 2).

In addition, polyalkylene glycol has also been proposed as a refrigerating machine oil used as a working medium component together with a hydrocarbon refrigerant (for example, Patent Documents 3 to 12).

International Publication No. 2000-60031 Japanese Unexamined Patent Publication No. 2003-041278 Japanese Unexamined Patent Publication No. 10-158671 International Publication No. 2006/03490 JP-A-2009-235111 Japanese Unexamined Patent Publication No. 2010-031728 Japanese Unexamined Patent Publication No. 2013-515838 Japanese Unexamined Patent Publication No. 2013-203988 Japanese Unexamined Patent Publication No. 2016-089103 Japanese Unexamined Patent Publication No. 2016-0332222 Japanese Unexamined Patent Publication No. 2017-0572778 Japanese Unexamined Patent Publication No. 2000-129275

However, the refrigerating machine oil containing the above-mentioned mineral oil, alkylbenzene or polyol ester proposed in Patent Document 1 and Patent Document 2 has good compatibility with hydrocarbon refrigerants such as propane and isobutane, and the amount of hydrocarbon refrigerant dissolved in the refrigerating machine oil. Will increase. Therefore, in order to exert sufficient capacity in the refrigeration cycle apparatus, it is necessary to fill the refrigeration cycle apparatus with a large amount of hydrocarbon refrigerant. However, since hydrocarbons such as propane and isobutane are highly flammable, it is desirable from the viewpoint of safety that the filling amount of such a hydrocarbon refrigerant is as small as possible within the range in which the operating efficiency is sufficiently exhibited. Further, it is preferable that the smaller the amount of the hydrocarbon refrigerant dissolved in the refrigerating machine oil, the smaller the fluctuation between the dissolution and evaporation of the hydrocarbon refrigerant in the refrigerating machine oil caused by the change in the operating conditions, and the smaller the change in the viscosity of the working medium. Further, when the amount of the hydrocarbon refrigerant dissolved in the refrigerating machine oil is small, the refrigerating machine oil having a lower viscosity can be selected, so that the efficiency of the refrigerating cycle device can be improved and energy saving can be achieved.

On the other hand, Patent Documents 3 to 12 propose many types of polyalkylene glycols as refrigerating machine oils for hydrocarbon refrigerants. It is said that polyalkylene glycol has a high polarity and is less soluble in a hydrocarbon refrigerant than the above-mentioned mineral oil, alkylbenzene and polyol ester. Examples and Comparative Examples of Patent Documents 3 to 11 disclose polypropylene glycol, polyethylene glycol polypropylene glycol, polyethylene glycol polypropylene glycol methyl ether and dimethyl ether, and polypropylene glycol dimethyl ether as polyalkylene glycols used as refrigerating machine oil. Specifically, in the present document, a refrigerating machine oil using a high-viscosity polyalkylene glycol having a kinematic viscosity of 46 mm ² / s (40 ° C) or higher; a kinematic viscosity of 5.3 to 22.4 mm ² / s (40 ° C). A frozen base oil in which two polyalkylene glycols having different viscosities of low-viscosity polyalkylene glycol and high-viscosity polyalkylene glycol having a kinematic viscosity of 1235 mm ² / s (40 ° C.) or more; etc. are disclosed.

Further, in the examples of Patent Document 12, low molecular weight polyalkylene glycol is exemplified. However, the low molecular weight polyalkylene glycol disclosed in Patent Document 12 does not have a sufficient low-temperature side critical dissolution temperature, and cannot be said to have sufficient compatibility with a hydrocarbon refrigerant as a refrigerating machine oil. For example, polyisopropylene glycol monobutyl ether having an average molecular weight of 200, 1000, and 1800 has critical dissolution temperatures on the low temperature side of -19 ° C., + 15 ° C., and + 20 ° C. or higher, respectively, and has low compatibility with propane.

As described above, the refrigerating machine oil containing polyalkylene glycol having a low viscosity, that is, a low molecular weight as a base oil is not necessarily compatible with the hydrocarbon refrigerant suitable as the refrigerating machine oil, and there is still room for improvement. there were.

In addition, refrigerating machine oil is used for a long time in a refrigerating cycle device in the coexistence with a refrigerant and is exposed to low and high temperatures, so that high thermochemical stability is required.

One of the objects of the present invention is that in a working medium for a refrigerant compression type refrigerating cycle device containing a refrigerant containing a hydrocarbon and a refrigerating machine oil, the refrigerating machine oil has appropriate compatibility with a refrigerant, low viscosity, and high thermal stability. It is to provide a working medium for a refrigerant compression type refrigeration cycle apparatus which achieves at least one of them.

According to the present invention, a refrigerant containing a hydrocarbon having 1 to 8 carbon atoms and the following general formula (1): R ¹ − (OR ² ) _{n −} OH [However, R ¹ is directly derived from 1 to 8 carbon atoms. It is an alkyl group of a chain or a branched chain, OR ² represents an oxyalkylene group having 2 and / or 3 carbon atoms, which is the same or different, and n is an addition molar of an oxyalkylene group represented by OR ^2. Represents a number. ], And the refrigerating machine oil containing a polyalkylene glycol having an average molecular weight of 200 to 1000, the OR ² in the general formula (1) contains an oxypropylene group, and the oxypropylene group is said. The content of the alkylene glycol having 80 mol% or more with respect to the total number of added moles of OR ² and n in the general formula (1) is 3 mass with respect to the total mass of the polyalkylene glycol. A working medium for a refrigerant compression refrigeration cycle device, which is less than or equal to%, is provided.

In one embodiment of the present invention, the refrigerating machine oil has a kinematic viscosity at 40 ° C. of 1 mm ² / s or more and 45 mm ² / s or less.

Further, in one embodiment of the present invention, when the vapor pressure of the refrigerant at 70 ° C. is 1.77 MPa, the saturated solubility of the refrigerant in refrigerating machine oil at 70 ° C. is 20% by mass or less.

According to the present invention, in a working medium for a refrigerant compression type refrigerating cycle apparatus containing a refrigerant containing a hydrocarbon and a refrigerating machine oil, the refrigerating machine oil has appropriate compatibility with a refrigerant, low viscosity, and high thermal stability. A working medium for a refrigerant compression refrigeration cycle device that achieves at least one is provided.

Hereinafter, the present invention will be described. The present invention is not limited to the following embodiments. Further, in the present specification, "X to Y" indicating a range means "X or more and Y or less". Unless otherwise specified, operations and physical properties are measured under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50% RH.

Hereinafter, the working medium for a refrigerant compression type refrigeration cycle device of the present invention (hereinafter, may also be simply referred to as “working medium”) will be described in detail. First, the working medium according to the present invention includes a refrigerant containing a hydrocarbon having 1 to 8 carbon atoms and a refrigerating machine oil containing a specific polyalkylene glycol (hereinafter, simply referred to as “polyalkylene glycol”). Further, in a preferred embodiment of the present invention, the refrigerating machine oil has a kinematic viscosity of 1 mm ² / s or more and 45 mm ² / s or less at 40 ° C. In the present specification, the kinematic viscosity is measured by the method described in Examples.

In the present invention, the refrigerating machine oil preferably contains polyalkylene glycol as a base oil. The base oil of the refrigerating machine oil refers to a component contained in an amount of more than 50% by mass (upper limit of 100% by mass) with respect to the total mass of the refrigerating machine oil, preferably a component contained in an amount of 80% by mass or more, more preferably 90% by mass. It is a component contained in an amount of mass% or more.

In a preferred embodiment of the present invention, the content of polyalkylene glycol in the refrigerating machine oil is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, based on the total mass of the refrigerating machine oil. It is even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 97% by mass or more. The refrigerating machine oil may be composed of only polyalkylene glycol, and therefore, the upper limit of the content of polyalkylene glycol in the refrigerating machine oil is 100% by mass with respect to the total mass of the refrigerating machine oil. When the polyalkylene glycol is contained within the above range, the effect of the present invention can be more exerted.

In the present invention, the refrigerating machine oil achieves at least one of appropriate compatibility with a refrigerant, low viscosity, and high thermal stability. The refrigerating machine oil is used together with the refrigerant as a component of an operating medium for a refrigerant compression type refrigerating cycle device. Refrigerant machine oils that have one or more (preferably two or more) of appropriate compatibility with the refrigerant, low viscosity, and high thermal stability can reduce the amount of refrigerant charged, thereby refrigerating. A working medium containing machine oil can exhibit good performance.

Therefore, another object of the present invention is to provide a working medium for a refrigerant compression type refrigerating cycle device and a refrigerating cycle device using the same, which exhibits good performance even when the amount of the refrigerant charged is small.

First, the refrigerant contained in the working medium of the present invention will be described. The refrigerant contains a hydrocarbon having 1 to 8 carbon atoms, preferably a hydrocarbon having 2 to 6 carbon atoms, more preferably a hydrocarbon having 2 to 5 carbon atoms, and further preferably having 3 to 5 carbon atoms. Contains hydrocarbons.

Hydrocarbons having 1 to 8 carbon atoms include, for example, methane, ethane, propane (R290), n-butane (normal butane) (R600), isobutane (R600a), n-pentane, n-hexane, n-heptane, and the like. It is n-octane. In a preferred embodiment, the refrigerant is a refrigerant containing propane (R290). In this case, in addition to propane, the refrigerant is saturated hydrocarbons such as ethane, n-butane (normal butane) (R600), isobutane (R600a); unsaturated hydrocarbons such as ethylene and propene; dimethyl ether; carbon dioxide; etc. Other refrigerants may be further contained. When the refrigerant containing propane further contains other refrigerants, the main component of the refrigerant is preferably propane. In the present invention, the "main component" means a component exceeding 50% by mass (upper limit 100% by mass) with respect to the total mass of the refrigerant.

When the refrigerant contains propane and another refrigerant, the propane content is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, based on the total mass of the refrigerant. In this case, the content of the other refrigerant is preferably less than 20 parts by mass, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, based on the total mass of the refrigerant. The lower limit of the content of the other refrigerant is not particularly limited, but practically, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or less, based on the total mass of the refrigerant.

In a preferred embodiment, the refrigerant used in combination with the refrigerating machine oil according to the present invention has a propane content of 100% by mass with respect to the total mass of the refrigerant (that is, the refrigerant is composed of propane alone). The refrigerating machine oil according to the present invention exerts a higher effect of the present invention when combined with a refrigerant composed of propane alone. That is, the effect of the present invention is more exerted by the combination of a specific polyalkylene glycol and a refrigerant composed of propane alone. Therefore, in a preferred embodiment, the refrigerant does not contain other refrigerants and contains propane alone.

Next, the specific polyalkylene glycol contained in the refrigerating machine oil of the present invention will be described. The specific polyalkylene glycol is represented by the following general formula (1) and has an average molecular weight of 200 to 1000.

R ^1- (OR ² ) _n- OH (1)
[However, R ¹ is a linear or branched alkyl group having 1 to 8 carbon atoms, and OR ² represents an oxyalkylene group having 2 carbon atoms and / or 3 carbon atoms, which is the same or different. Represents the number of added moles of the oxyalkylene group represented by OR ² . ].

Further, in the specific polyalkylene glycol, OR ² contains an oxypropylene group in the general formula (1), and the oxypropylene group is 80 mol% or more with respect to the total number of moles of OR ² . Further, the specific polyalkylene glycol has a content of alkylene glycol having n of 1 in the general formula (1) of 3% by mass or less based on the total mass of the polyalkylene glycol.

In the above general formula (1), R ¹ represents a linear or branched alkyl group having 1 to 8 carbon atoms. From the viewpoint of the balance between the solubility of the refrigerant in refrigerating machine oil and the characteristics as refrigerating machine oil, an alkyl group having 1 to 5 carbon atoms is more preferably used as the alkyl group, for example, a methyl group, an ethyl group, a linear group or a branched group. Examples thereof include a linear or branched propyl group, a linear or branched butyl group, and a linear or branched pentyl group. R ¹ is further preferably a linear or branched alkyl group having 3 to 5 carbon atoms, more preferably an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group, and particularly carbon. The linear or branched butyl group of No. 4 (n-butyl group, isobutyl group, tert-butyl group) is more preferable. Most preferably, it is a linear butyl group (n-butyl group) having 4 carbon atoms. When R ¹ is an alkyl group having the above carbon number, it is excellent in low temperature fluidity because it is a short chain alkyl group.

Further, in the above general formula (1), OR ² represents an oxyalkylene group having 2 carbon atoms and / or 3 carbon atoms, which is the same or different. That is, R ² represents the same or different alkylene group having 2 carbon atoms and / or the alkylene group having 3 carbon atoms. However, OR ² may contain a small amount of oxybutylene group having 4 carbon atoms so as not to affect the characteristics of the refrigerating machine oil. Specific examples of such an oxyalkylene group include an oxyethylene group (-OCH ₂ CH _2- ), an oxypropylene group (-OCH (CH ₃ ) CH _2- ), and an oxytrimethylene group (-OCH ₂ CH _2-). CH _2- ) and the like can be mentioned. Among these oxyalkylene groups, an oxyethylene group and an oxypropylene group are preferable, and an oxypropylene group is more preferable. At this time, the oxyalkylene group (OR ² ) in the repeating unit represented by (OR ² ) _n may be the same oxyalkylene group or a different oxyalkylene group.

In the polyalkylene glycol represented by the general formula (1), OR ² is an oxypropylene group (-OCH (CH ₃ ) CH _2- ) (that is, R ² is a branched alkylene group having 3 carbon atoms; isopropylene. The oxypropylene group is 80 mol% or more based on the total number of moles of OR ² added. In the polyalkylene glycol, the oxypropylene group is more preferably 90 mol% or more, still more preferably 95 mol% or more, based on the total number of moles of OR ² . When the ratio of the oxypropylene group to the total OR ² in the polyalkylene glycol is within the above range, it is possible to improve the characteristics of the refrigerating machine oil, that is, the compatibility with the hydrocarbon refrigerant. The upper limit of the ratio of the oxypropylene group to the total OR ² in the polyalkylene glycol is not particularly limited, but it is most preferable that the OR ² is entirely composed of oxypropylene in the polyalkylene glycol, and therefore the upper limit is 100 mol. %.

For example, when OR ² is composed of an oxyethylene group (-OCH ₂ CH _2- ) (that is, R ² is a linear alkylene group having 2 carbon atoms; an ethylene group) and an oxypropylene group, the oxypropylene group is an oxy. It is preferably 80 mol% or more with respect to the total number of moles of ethylene group and oxypropylene group added.

Further, in the above general formula (1), n represents the number of moles (degree of polymerization) of the oxyalkylene group represented by OR ² . The number average molecular weight of the polyalkylene glycol represented by the general formula (1) is 200 to 1000, preferably 300 to 1000, more preferably 350 to 900, and further preferably 350 to 850. Even more preferably, it is 350 to 800, and particularly preferably 350 to 700. n is preferably a number such that the number average molecular weight of the polyalkylene glycol satisfies the above conditions. For example, n is preferably 2 to 40, more preferably 2 to 30. If the number average molecular weight of the polyalkylene glycol is less than 200 and is too low, the lubricity of the refrigerating machine oil in the coexistence of the refrigerant becomes insufficient. On the other hand, if the number average molecular weight is more than 1000 and too high, the viscous resistance of the refrigerating machine oil becomes too high and the efficiency of the refrigerating cycle apparatus decreases. In the present specification, the number average molecular weight is measured by GPC (gel permeation chromatography) using polystyrene as a standard substance. The number of added moles n in the general formula (1) can be calculated based on the number average molecular weight obtained by the measurement.

The polyalkylene glycol according to the present invention can be synthesized by using a conventionally known method (“alkylene oxide polymer”, Mitsuta Shibata et al., Kaibundo Publishing Co., Ltd., published on November 20, 1990). For example, an alcohol (R 1 ^OH; R ¹ represents the same definition as R ¹ in the general formula (1)) obtained by addition polymerization of one or more predetermined alkylene oxide to. When two or more different types of alkylene oxides are used in the above production step, the obtained polyalkylene glycol may be either a random copolymer or a block copolymer.

Examples of the polyalkylene glycol represented by the general formula (1) include polypropylene glycol monomethyl ether, polyethylene glycol / polypropylene glycol copolymer monomethyl ether (polyethylene glycol polypropylene glycol monomethyl ether); polypropylene glycol monoethyl ether, polyethylene glycol. -Polyethylene glycol monoethyl ether (polyethylene glycol polypropylene glycol monoethyl ether); polypropylene glycol mono n-propyl ether, polyethylene glycol / polypropylene glycol copolymer mono n-propyl ether (polyethylene glycol polypropylene glycol mono n-) (Propyl ether); polypropylene glycol monoisopropyl ether, polyethylene glycol / polypropylene glycol copolymer monoisopropyl ether (polyethylene glycol polypropylene glycol monoisopropyl); polypropylene glycol mono n-butyl ether, polyethylene glycol / polypropylene glycol copolymer mono n- Butyl ether (polyethylene glycol polypropylene glycol mono n-butyl ether); polypropylene glycol monoisobutyl ether, polyethylene glycol / polypropylene glycol copolymer monoisobutyl ether (polyethylene glycol polypropylene glycol monoisobutyl ether); polypropylene glycol monotert-butyl ether, polyethylene glycol. Mono tert-butyl ether of a polypropylene glycol copolymer (polyethylene glycol polypropylene glycol mono tert-butyl ether); and the like.

Among these polyalkylene glycols, polyalkylene glycol is polypropylene glycol mono-n-propyl ether, polyethylene glycol / polypropylene glycol copolymer mono-n-propyl ether, polypropylene glycol monoisopropyl ether, polyethylene glycol / polypropylene glycol copolymer. Monoisopropyl ether, polypropylene glycol monon-butyl ether, polyethylene glycol / polypropylene glycol copolymer monon-butyl ether, polypropylene glycol monoisobutyl ether, polyethylene glycol / polypropylene glycol copolymer monoisobutyl ether, polypropylene glycol monotert- Butyl ether and monotert-butyl ether of polyethylene glycol / polypropylene glycol copolymer are preferable.

Further, the polyalkylene glycols are polypropylene glycol monoisopropyl ether, polyethylene glycol / polypropylene glycol copolymer monoisopropyl ether, polypropylene glycol monon-butyl ether, polyethylene glycol / polypropylene glycol copolymer monon-butyl ether, and polypropylene glycol mono. More preferably, isobutyl ether, monoisobutyl ether of polyethylene glycol / polypropylene glycol copolymer, monotert-butyl ether of polypropylene glycol monotert-butyl ether, and monotert-butyl ether of polyethylene glycol / polypropylene glycol copolymer.

In a preferred embodiment, the refrigerating machine oil contains polypropylene glycol monobutyl ether (at least one selected from polypropylene glycol monon-butyl ether, polypropylene glycol monoisobutyl ether and polypropylene glycol monotert-butyl ether) as polyalkylene glycol. More preferably, the refrigerating machine oil contains polypropylene glycol mono-n-butyl ether as polyalkylene glycol.

Here, the polyalkylene glycol contained in the refrigerating machine oil of the present invention have the general formula (1) alkylene glycol n is 1 in (i.e., R 1 ^- (OR 2) ^-OH, hereinafter, both "monoadduct" The content of (referred to as) is 3% by mass or less based on the total mass of the polyalkylene glycol. The content of the monoadduct in the polyalkylene glycol is preferably 2% by mass or less, more preferably 1.5% by mass or less, still more preferably 1.2% by mass or less, and further, based on the total mass of the polyalkylene glycol. It is more preferably 1% by mass or less, and particularly preferably 0.9% by mass or less. The mono-additive is R ^1- (OR ² ) -OH (R ¹ is a linear or branched alkyl group having 1 to 8 carbon atoms, and OR ² is an oxy having 2 or 3 carbon atoms. Represents an alkylene group), specifically R ^1- (OCH ₂ CH ₂ ) -OH (ethylene glycol monoalkyl ether) and R ^1- (OCH ₂ (CH ₃ ) CH ₂ ) -OH ( Propylene glycol monoalkyl ether) at least one of them. It is preferable that the polyalkylene glycol does not contain the monoadduct at all, but when it is unavoidably contained, the content of the monoadduct in the polyalkylene glycol is practically based on the total mass of the polyalkylene glycol. , 0.01% by mass or more, 0.05% by mass or more.

The present inventors have found that a refrigerating machine oil containing a polyalkylene glycol having a monoadditive content of more than 3% by mass has reduced thermal stability, boiling point, and flash point, and the monoadduct in the polyalkylene glycol. It was found that the content of the refrigerating machine oil has a great influence on the characteristics of the refrigerating machine oil. This mechanism is presumed as follows.

Low molecular weight polyalkylene glycol having a number average molecular weight of 200 to 1000 has lower thermal stability, lower boiling point and flash point, and higher water absorption than high molecular weight polyalkylene glycol. Further, in a low molecular weight polyalkylene glycol having a number average molecular weight of 200 to 1000, a monoadduct in which 1 mol of alkylene oxide is added to alcohol (n = 1) is likely to be produced during production. The inventors have found that this monoadduct is an unfavorable component for refrigerating machine oil because it has lower thermal stability, lower boiling point and flash point, and higher water absorption than low molecular weight polyalkylene glycol. I found it. Therefore, it is considered that such a monoadduct has a large influence on the low molecular weight polyalkylene glycol, and the characteristics as a refrigerating machine oil are significantly deteriorated.

The present inventors have found that in the low molecular weight polyalkylene glycol, the characteristics as a refrigerating machine oil can be improved by limiting the content of the monoadduct to a specific value or less. That is, they have found that the polyalkylene glycol having a low content of the mono-adduct has excellent properties as a refrigerating machine oil, that is, has appropriate properties as a refrigerating machine oil. Needless to say, in the present invention, the mechanism by which the above effects are obtained is merely speculation by the present inventors, and the technical scope is bound by the mechanism, and the present invention is not limited. It has been confirmed in Examples that the polyalkylene glycol having a low content of the monoadduct has high thermal stability.

Further, the refrigerating machine oil containing a specific polyalkylene glycol has excellent compatibility with a refrigerant containing a hydrocarbon having 1 to 8 carbon atoms. Although the mechanism by which the above effects are obtained in the present invention is unknown, the refrigerating machine oil of the present invention is suitably used as a working medium in combination with the refrigerant because the refrigerating machine oil has excellent compatibility with the refrigerant.

In the present invention, "excellent in compatibility with the refrigerant (having appropriate compatibility with the refrigerant)" means that the two-layer separation temperature is low and the mixture is not too soluble in the refrigerant. In the present invention, the two-layer separation temperature of the refrigerant and the refrigerating machine oil is preferably −30 ° C. or lower, more preferably −35 ° C. or lower, still more preferably −40 ° C. or lower, and even more preferably −. It is 45 ° C. or lower. The lower limit of the two-layer separation temperature is determined by the balance between the return of refrigerating machine oil from the evaporator to the compressor and the lubricity of the refrigerating machine oil in the refrigeration cycle, and depends on the design of the refrigeration system. The two-layer separation temperature is measured by the method described in Examples described later. Further, the polyalkylene glycol has a higher polarity than the mineral oil and the polyol ester, and does not dissolve too much in the hydrocarbon refrigerant. Therefore, the refrigerating machine oil according to the present invention does not dissolve too much with the refrigerant by containing the polyalkylene glycol. As described above, since the refrigerating machine oil according to the present invention has excellent compatibility with the refrigerant (having appropriate compatibility with the refrigerant), the working medium containing the refrigerating machine oil according to the present invention is a highly flammable hydrocarbon. Good performance can be exhibited even if the filling amount of the refrigerant is small.

Further, in the present invention, the polyalkylene glycol contained in the refrigerating machine oil has a small content of the monoadduct, so that there are few volatile components and excellent thermal stability. In the present invention, excellent thermal stability means that the weight change of the refrigerating machine oil is small before and after the thermal stability test (detailed method is described in Examples described later); the change of the kinematic viscosity of the refrigerating machine oil is small. Low; before and after the thermo-chemical stability test (detailed method is described in Examples below), the acid value of the refrigerating machine oil is 0.01-0.05 mgKOH / g; the hue of the refrigerating machine oil is L0.5. It achieves at least one of ~ L1.0; Of these, it is particularly preferable to achieve two things: a small change in the weight of the refrigerating machine oil; a small change in the kinematic viscosity of the refrigerating machine oil before and after the thermal stability test. In the thermal stability test, "small change" means that the rate of change is 0 to 3% when compared before and after the test. Such a refrigerating machine oil having excellent thermal stability is preferably used as a working medium. When the acid value is within the above range before and after the thermal / chemical stability test, it can be said that the thermal stability is excellent. Further, when the hue of the refrigerating machine oil is within the above range before and after the thermal / chemical stability test, it can be said that the thermal stability is excellent.

Here, the method for adjusting the content of the mono-addition in the polyalkylene glycol to obtain the polyalkylene glycol having a small content of the mono-addition is not particularly limited and may be a known method. For example, a method of removing the monoadduct by performing distillation, vacuum treatment, adsorption treatment, washing with water, or the like on the obtained polyalkylene glycol after producing the polyalkylene glycol can be mentioned.

Specifically, the produced polyalkylene glycol is charged into a reactor equipped with a stirrer, a heating device, a cooling condenser, a receiver and a vacuum pump in a nitrogen atmosphere. The polyalkylene glycol in the reactor is heated to 80 to 100 ° C. with stirring, and then placed under a reduced pressure of 15 to 30 mmHg for 2 to 3 hours to carry out a reduced pressure treatment to add mono addition to the polyalkylene glycol. The body can be removed. Further, the time of the depressurization treatment can be shortened by increasing the degree of vacuum in the reactor. By recovering the removed monoadduct, it can be used as a raw material in the subsequent production of polyalkylene glycol. All of the polyalkylene glycols in the examples are also prepared by performing such an operation. As described above, in the low molecular weight polyalkylene glycol having a number average molecular weight of 200 to 1000, a monoadduct in which 1 mol of alkylene oxide is added to alcohol (n = 1) is likely to be produced during production. Therefore, it is considered that the content of the monoadductent in the polyalkylene glycol cannot be reduced to 3% by mass or less unless such an operation is performed.

From the viewpoint of the efficiency of the refrigeration cycle apparatus, the kinematic viscosity of the refrigerating machine oil of the present invention at 40 ° C. is preferably 1 mm ² / s or more and 45 mm ² / s or less. The upper limit of the kinematic viscosity at 40 ° C. of the refrigerating machine oil is preferably not more than 38mm ² / s, more preferably 35 mm ² / s or less, more preferably at most 30mm ^² / s, 22mm ² / It is even more preferably s or less, and particularly preferably 15 mm ² / s or less. Further, the upper limit of the kinematic viscosity at 40 ° C. of the refrigerating machine oil, in turn, 14 mm ² / s or less, 13 mm ² / s or less, preferably less than 13 mm ² / s. Further, the lower limit of the kinematic viscosity of the refrigerating machine oil at 40 ° C. is more preferably 1 mm ² / s or more, further preferably 3 mm ² / s or more, still more preferably 5 mm ² / s or more, and particularly preferably 7 mm ² / S or more. When the kinematic viscosity of the refrigerating machine oil is within the above range, the effect of the present invention is more exhibited.

The kinematic viscosity of the polyalkylene glycol at 40 ° C. is preferably 1 mm ² / s or more and 45 mm ² / s or less, more preferably 3 mm ² / s or more and 38 mm ² / s or less, and further preferably 5 mm ² / s. It is s or more and 35 mm ² / s or less, more preferably 5 mm ² / s or more and 30 mm ² / s or less, and particularly preferably 7 mm ² / s or more and 22 mm ² / s or less. In a preferred embodiment, since the refrigerating machine oil contains 85% by mass or more (most preferably 100% by mass) of polyalkylene glycol with respect to the total mass of the refrigerating machine oil, the kinematic viscosity of the polyalkylene glycol and the kinematic viscosity of the refrigerating machine oil are substantially the same. It is the same.

The pour point of the polyalkylene glycol is preferably −10 ° C. or lower, more preferably −20 ° C. or lower, further preferably −30 ° C. or lower, and preferably −40 ° C. or lower. Even more preferable. When a polyalkylene glycol having a pour point of more than −10 ° C. is used, the refrigerating machine oil tends to solidify in the refrigerant circulation system at a low temperature. The pour point is measured by the method described in Examples described later.

Further, the flash point of the polyalkylene glycol is preferably 120 ° C. or higher, more preferably 150 ° C. or higher. It is preferable to use a polyalkylene glycol having a flash point of 120 ° C. or higher because it is not only easy to handle but also safe in the drying step after injecting the refrigerating machine oil at the time of producing the compressor. The flash point is measured by the method described in Examples described later.

Here, when the vapor pressure of the refrigerant at 70 ° C. is 1.77 MPa (that is, when the refrigerant is composed of propane alone), the saturated solubility of the refrigerant in the refrigerating machine oil at 70 ° C. is 20% by mass or less. Is preferable. The saturated solubility of the refrigerant having a vapor pressure of 1.77 MPa at 70 ° C. in refrigerating machine oil was based on the method described in International Publication No. 2005/095557. Specifically, a predetermined amount of refrigerating machine oil and a refrigerant were sealed in a glass pressure-resistant container, and the temperature was raised from room temperature to 80 ° C. A temperature / pressure / solubility curve was created by calculation from the volume of refrigerating machine oil in which the refrigerant was dissolved and the pressure at that time. From this solubility curve, the solubility (mass%) of the refrigerant in the refrigerating machine oil at 70 ° C. was calculated.

Since the polyalkylene glycol of the present embodiment has a hydroxyl group having a large polarity at one end, it is considered that the polyalkylene glycol has a small affinity with a non-polar hydrocarbon refrigerant and the amount of dissolution thereof can be reduced. Therefore, the filling amount of the hydrocarbon refrigerant (preferably the refrigerant containing propane) in the working medium can be reduced. Further, since the hydroxyl group has a large adsorption force to the metal material, it is easy to form an adsorption film on the sliding material of the compressor, which is the heart of the refrigeration cycle device, and exhibits good lubricity (wear resistance). Further, the polyalkylene glycol of the present embodiment is also excellent in characteristics as a refrigerating machine oil (for example, thermal stability) because it is a polyalkylene glycol having a low content of a monoadduct. From this, it is presumed that the use of a specific polyalkylene glycol in the present invention can reduce the viscosity of the refrigerating machine oil and lead to higher efficiency of the refrigerating cycle apparatus. The present invention is not limited by the above reasoning.

The refrigerating machine oil according to the present embodiment may be composed of only the above-mentioned polyalkylene glycol (that is, the content of the polyalkylene glycol is 100% by mass), but as long as the function as the refrigerating machine oil is satisfied. , Ingredients (base oil and additives) other than the above polyalkylene glycol can be further contained. In this case, the content of the polyalkylene glycol in the refrigerating machine oil is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 85% by mass or more, based on the total amount of the refrigerating machine oil. It is 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 97% by mass or more.

Other base oils that can be contained in the refrigerating machine oil according to the present embodiment include esters, polyalkylene glycols having both ends esterified, and ethers such as polyalkylene glycols having both ends or one end esterified and polyvinyl ethers. , Hydrocarbon-based alkylbenzene, mineral oil and the like.

Further, the refrigerating machine oil according to the present embodiment can further contain a stability improving agent as an additive in order to further enhance the stability of the working medium between the refrigerant and the refrigerating machine oil in actual use. Preferred stability improvers include one or more of thiobisphenol compounds and aromatic amine compounds, and it is more preferable to use the thiobisphenol compound and the aromatic amine compound in combination. Further, the refrigerating machine oil according to the present embodiment can further contain an oily agent such as a partial ester of a polyhydric alcohol as an additive. The total content of the stability improver and the oily agent is preferably 0.1 to 3.0% by mass based on the total amount (total mass) of the refrigerating machine oil. That is, the refrigerating machine oil preferably contains one or more additives selected from the group consisting of amine compounds, phenol compounds, and partial esters of polyhydric alcohols in an amount of 0.1 to 3.0 based on the total amount of refrigerating machine oil. It is contained in an amount of% by mass, more preferably 0.2 to 2% by mass, still more preferably 0.3 to 1.5% by mass.

Further, among the stability improvers, as the phenol compound, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol and the like are preferable. The content of the phenol compound is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.5% by mass, based on the total amount of refrigerating machine oil. Examples of the thiobisphenol compound include 4,4'-thiobis (2,6-di-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), and 4,4'-thiobis (3). -Methyl-6-tert-butylphenol) and the like are suitable. The content of the thiobisphenol compound is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.5% by mass, based on the total amount of refrigerating machine oil.

Examples of the aromatic amine compound include α-naphthylamine and N-phenyl-1-naphthylamine, which are di (alkylphenyl) amines having an alkyl group having 4 to 12 carbon atoms (for example, p, p'-di). -Octyl-diphenylamine), alkylated phenyl-α-naphthylamine, and alkylated phenyl-β-naphthylamine are preferable. The content of the aromatic amine compound is preferably 0.05 to 1.5% by mass, more preferably 0.1 to 1.0% by mass, based on the total amount of refrigerating machine oil.

Examples of the partial ester of the polyhydric alcohol include glycerin monooleate (glycerol monooleate) and sorbitan monooleate, and the content of the partial ester of the polyhydric alcohol is preferably based on the total amount of refrigerating machine oil. Is 0.01 to 1.0% by mass, more preferably 0.05 to 0.5% by mass. When the partial ester of the polyhydric alcohol is a monoester, the monoester is susceptible to hydrolysis. Therefore, the content of the partial ester of the polyhydric alcohol is preferably 0.01% by mass or more based on the total amount of refrigerating machine oil. It is less than 0.1% by mass, more preferably 0.01% by mass or more and less than 0.05% by mass.

Further, the refrigerating machine oil according to the present embodiment includes antioxidants such as hindered phenol, abrasion inhibitors such as phosphoric acid esters and organic sulfur compounds, oily agents such as monohydric alcohols and higher fatty acids, and benzotriazole derivatives. Additives such as a metal inactivating agent and a defoaming agent such as silicone oil can be appropriately added.

The refrigerating machine oil of the present invention usually exists in a refrigerating cycle apparatus in the form of a working medium mixed with a hydrocarbon refrigerant (preferably a refrigerant containing propane) as described above. The mixing ratio of the refrigerating machine oil and the refrigerant containing hydrocarbons having 1 to 8 carbon atoms (preferably the refrigerant containing propane) in this working medium is not particularly limited, but the refrigerant containing hydrocarbons having 1 to 8 carbon atoms (preferably). Refrigerant oil is preferably 1 to 500 parts by mass, more preferably 2 to 400 parts by mass, and further preferably 4 to 300 parts by mass with respect to 100 parts by mass of the refrigerant containing propane.

According to the present invention, a refrigeration cycle device using the above working medium is also provided. That is, the working medium of the present invention can be suitably used for a refrigeration cycle device, and is preferably used, for example, in an electric refrigerator or an air conditioner having a reciprocating or rotary sealed compressor. Further, the working medium of the present invention is preferably used for a cooling device such as a dehumidifier, a water heater, a freezer, a freezer / refrigerator warehouse, a showcase, a vending machine, and a chemical plant. Further, it is also preferably used for those having a centrifugal compressor.

As described above, the present invention also has one of the features in using a specific polyalkylene glycol. Therefore, in one embodiment of the present invention, the following general formula (1): R ¹ − (OR ² ) _{n −} OH [where R ¹ is a linear or branched alkyl group having 1 to 8 carbon atoms. , OR ² represent the same or different oxyalkylene groups having 2 and / or 3 carbon atoms, and n represents the number of additional moles of the oxyalkylene group represented by OR ² . Represented by] comprising the refrigeration oil average molecular weight comprises a polyalkylene glycol is from 200 to 1000, the OR ² in the general formula (1) comprises a oxypropylene group, the oxypropylene group, said OR ² The content of the alkylene glycol having 80 mol% or more and n in the general formula (1) is 3% by mass or less with respect to the total mass of the polyalkylene glycol. A working medium for a refrigerant compression type refrigeration cycle device is also provided.

Therefore, in one embodiment of the present invention, the following general formula (1): R ¹ − (OR ² ) _{n −} OH [where R ¹ is a linear or branched alkyl group having 1 to 8 carbon atoms. , OR ² represent the same or different oxyalkylene groups having 2 and / or 3 carbon atoms, and n represents the number of additional moles of the oxyalkylene group represented by OR ² . ], The OR ² contains an oxypropylene group in the general formula (1), and the oxypropylene group is the total addition molar of the OR ² and contains a polyalkylene glycol having an average molecular weight of 200 to 1000. A refrigerant having a content of 80 mol% or more and 3% by mass or less based on the total mass of the polyalkylene glycol having n of 1 in the general formula (1). Refrigerating machine oil for compression refrigeration cycle devices is also provided.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

In the following examples, pentane may be used instead of propane as the refrigerant. From the viewpoint of polarity or relative permittivity, pentane is considered to exhibit the same compatibility with propane as a refrigerant with respect to refrigerating machine oil. Further, it has been confirmed that the two-layer separation temperature described later can be the same value as when propane is used as the refrigerant even when pentane is used as the refrigerant. Therefore, in the following examples, the example using pentane as the refrigerant is considered to satisfy the constituent requirements of the present invention.

[Example (A)]
In Example 1 and Comparative Examples 1 and 2, refrigerating machine oils having the following configurations were prepared. In the composition of the refrigerating machine oil below, the "content of the mono-adduct" refers to the mono-adduct of the alkylene oxide in the polyalkylene glycol monoalkyl ether used (hereinafter, may be abbreviated as "PAG-AE"). Represents the content of. In the case of refrigerating machine oil containing additives, the balance of the additive content is the base oil content. Therefore, in the case of refrigerating machine oil containing no additives, the refrigerating machine oil is composed of a base oil.

(Example 1)
Polypropylene glycol monobutyl ether (number average molecular weight: 400, content of mono-additive (propylene glycol monobutyl ether): 0.5% by mass) in which R ¹ (terminal) is an n-butyl group and OR ² is an oxypropylene group. It was used as the base oil for refrigerating machine oil (without additives).

(Comparative Example 1)
Polypropylene glycol monobutyl ether (number average molecular weight: 200, content of mono-additive (propylene glycol monobutyl ether): 28.8% by mass) in which R ¹ (terminal) is an n-butyl group and OR ² is an oxypropylene group. It was used as the base oil for refrigerating machine oil (without additives).

(Comparative Example 2)
Polypropylene glycol monobutyl ether (number average molecular weight: 400, content of mono-additive (propylene glycol monobutyl ether): 5.1% by mass) in which R ¹ (terminal) is an n-butyl group and OR ² is an oxypropylene group. It was used as the base oil for refrigerating machine oil (without additives).

Evaluation tests were carried out for each refrigerating machine oil prepared in Example 1 and Comparative Examples 1 and 2 according to the following method. In addition, the content of the monoadduct in PAG-AE used in each of the refrigerating machine oils of Example 1 and Comparative Examples 1 and 2 was measured according to the following method. The results obtained are shown in Table 1.

[Thermal stability test]
The thermal stability test of refrigerating machine oil was carried out in accordance with the JIS method (petroleum products-lubricating oil-thermal stability test method: K2540 (2000)). However, the test temperature was 120 ° C. and the test time was 24 hours. The weight and kinematic viscosity of the sample were measured before and after the test, and the changes were evaluated.

[Kinematic viscosity]
The kinematic viscosity of the refrigerating machine oil was measured in accordance with the JIS method (kinematic viscosity: K2283 (2000)).

[Two-layer separation temperature]
As a compatibility test between the refrigerating machine oil and the refrigerant, the two-layer separation temperature was measured in accordance with the JIS method (refrigerating machine oil: K2211 (2009)). The compatibility test was carried out using pentane instead of propane as the refrigerant, and 7.5 g of refrigerating machine oil with respect to 42.5 g of the refrigerant. In this example, the measurement was performed in the temperature range from room temperature (25 ° C.) to −50 ° C. Therefore, in the case of a sample containing refrigerating machine oil and a refrigerant, if separation does not occur even at -50 ° C, the two-layer separation temperature is "-50 ° C or less" (described as "<-50 ° C" in the table). evaluated.

[Content of mono-adduct]
The content of the mono-adduct (alkylene monoalkyl ether with n = 1 added moles of oxyalkylene group) in PAG-AE is a gas using a methyl silicon capillary column CBP1-M25-025 (25 m) manufactured by Shimadzu Corporation. Determined by chromatography. The content of the monoadduct was determined from the relative ratio of the peak areas (the peak area of the monoadduct to the total peak area of the polyalkylene glycol monoalkyl ether).

From Table 1, when the content of the monoadduct in PAG-AE used as the refrigerating machine oil exceeds 3% by mass in the thermal stability test, the weight is greatly reduced after the stability test of the refrigerating machine oil, and the movement is increased. It can be seen that the viscosity is increasing. If the weight loss is large and the kinematic viscosity changes, not only is it difficult to handle as refrigerating machine oil, but it is also difficult to design a refrigerating system, which is economically disadvantageous. When the content of the monoadduct in PAG-AE used as the refrigerating machine oil is 3% by mass or less, the kinematic viscosity of the refrigerating machine oil is 1 mm ² / s or more and 45 mm ² / s or less, and the two-layer separation temperature. The temperature was -30 ° C or lower, and it was found that the working medium containing the refrigerating machine oil was suitable as the working medium of the refrigeration cycle apparatus.

[Example (B)]
In Examples 2 to 4 and Comparative Examples 3 and 4, refrigerating machine oils having the following configurations were prepared.

(Example 2)
Polypropylene glycol monobutyl ether (number average molecular weight: 800, content of mono-additive (propylene glycol monobutyl ether): 0.8% by mass) in which R ¹ (terminal) is an n-butyl group and OR ² is an oxypropylene group. It was used as the base oil for refrigerating machine oil (without additives).

(Example 3)
Polyethylene glycol polypropylene glycol monobutyl ether (number average) in which R ¹ (terminal) is an n-butyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 1:19. The molecular weight was 800, and the content of the mono-additive (total of ethylene glycol monobutyl ether and propylene glycol monobutyl ether): 1.0% by mass) was used as the base oil of the refrigerating machine oil (no additive was added).

(Example 4)
Polyethylene glycol polypropylene glycol monobutyl ether (number average) in which R ¹ (terminal) is an n-butyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 1: 4. The molecular weight was 800, and the content of the mono-additive (total of ethylene glycol monobutyl ether and propylene glycol monobutyl ether): 0.7% by mass) was used as the base oil of the refrigerating machine oil (no additive was added).

(Comparative Example 3)
Polyethylene glycol polypropylene glycol monobutyl ether (number average) in which R ¹ (terminal) is an n-butyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 1: 1. The molecular weight was 450, and the content of the mono-additive (total of ethylene glycol monobutyl ether and propylene glycol monobutyl ether): 0.9% by mass) was used as the base oil for the refrigerating machine oil (without the addition of additives).

(Comparative Example 4)
Polyethylene glycol polypropylene glycol monobutyl ether (number average) in which R ¹ (terminal) is an n-butyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 3: 7. The molecular weight: 800) and the content of the mono-additive (total of ethylene glycol monobutyl ether and propylene glycol monobutyl ether): 0.4% by mass) were used as the base oil of the refrigerating machine oil (without the addition of additives).

Next, each refrigerating machine oil prepared in Examples 2 to 4 and Comparative Examples 3 and 4 was subjected to an evaluation test according to the above measurement method. The results obtained are shown in Table 2.

From Table 2, it was found that in PAG-AE having an oxyethylene group and an oxypropylene group, when the molar ratio of the oxyethylene group exceeds 20 mol%, the two-layer separation temperature with pentane tends to increase. ..

[Example (C)]
In Examples 5 to 10 and Comparative Examples 5 to 7, refrigerating machine oil having the following composition was prepared. In the following, when an additive is added to the refrigerating machine oil, the balance of the additive compounding amount is the base oil compounding amount.

(Example 5)
Polypropylene glycol mono tert-butyl ether (number average molecular weight: 400, mono-adduct (propylene glycol mono tert-butyl ether) content: 1.1) in which R ¹ (terminal) is a tert-butyl group and OR ² is an oxypropylene group. Mass%) was used as the base oil for refrigerating machine oil (no additives were added).

(Example 6)
R ¹ (terminal) is a tert-butyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 1: 9. Polyethylene glycol polypropylene glycol mono tert-butyl ether ( Number average molecular weight: 600, mono-additive (total of ethylene glycol mono tert-butyl ether and propylene glycol mono tert-butyl ether) content: 0.6% by mass) as the base oil for refrigerating machine oil, and as an additive 4, 4'-thiobis (2-methyl-6-tert-butylphenol) was blended so as to be 0.2% by mass based on the total amount of refrigerating machine oil to prepare refrigerating machine oil.

(Example 7)
Content of polypropylene glycol monobutyl ether (number average molecular weight: 800, total mono-additive (total of propylene glycol monobutyl ether)) in which R ¹ (terminal) is an n-butyl group and OR ² is an oxypropylene group: 0.8% by mass ) Was used as the base oil of the refrigerating machine oil, and p, p'-di-octyl-diphenylamine was blended as an additive so as to be 0.5% by mass with respect to the total amount of the refrigerating machine oil to prepare the refrigerating machine oil.

(Example 8)
Polyethylene glycol polypropylene glycol monoisopropyl ether (number average molecular weight) in which R ¹ (terminal) is an isopropyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 1: 9. : 1000, content of mono-adduct (total of ethylene glycol monoisopropyl ether and propylene glycol monoisopropyl ether): 0.3% by mass) was used as the base oil for refrigerating machine oil, and p, p'-di- was used as an additive. Refrigerating machine oil was prepared by blending octyl-diphenylamine in an amount of 0.5% by mass based on the total amount of refrigerating machine oil and glycerol monooleate in an amount of 0.08% by mass based on the total amount of refrigerating machine oil.

(Example 9)
Frozen polypropylene glycol monobutyl ether (number average molecular weight: 950, content of monoadduct (propylene glycol monobutyl ether): 0.3 mass) in which R ¹ (terminal) is an n-butyl group and OR ² is an oxypropylene group. As the base oil for machine oil, 4,4'-thiobis (2-methyl-6-tert-butylphenol) as an additive was added in an amount of 0.2% by mass based on the total amount of refrigerating machine oil, p, p'-di-octyl-diphenylamine. Was blended in an amount of 0.5% by mass based on the total amount of the refrigerating machine oil and glycerol monooleate was blended so as to be 0.08% by mass based on the total amount of the refrigerating machine oil to prepare the refrigerating machine oil.

(Comparative Example 5)
The viscosity grade (VG) 22 of the paraffinic mineral oil was used as the base oil for the refrigerating machine oil (without the addition of additives).

(Comparative Example 6)
VG46, a paraffinic mineral oil, was used as the base oil for refrigerating machine oil (without additives).

(Example 10)
Polyethylene glycol polypropylene glycol monoisopropyl ether (number average molecular weight) in which R ¹ (terminal) is an isopropyl group, OR ² is an oxyethylene group and an oxypropylene group, and the molar ratio of the oxyethylene group to the oxypropylene group is 1: 9. : 900, content of mono-adduct (total of ethylene glycol monoisopropyl ether and propylene glycol monoisopropyl ether): 0.2% by mass) was used as the base oil for refrigerating machine oil, and as an additive, p, p'-di- Refrigerating machine oil was prepared by blending octyl-diphenylamine in an amount of 0.5% by mass based on the total amount of refrigerating machine oil and glycerol monooleate in an amount of 0.2% by mass based on the total amount of refrigerating machine oil.

(Comparative Example 7)
Content of polypropylene glycol monoisopropyl ether (number average molecular weight: 1200, total mono-adduct (total of propylene glycol monoisopropyl ether)) in which R ¹ (terminal) is an isopropyl group and OR ² is an oxypropylene group: 0.1% by mass. ) Is used as the base oil for refrigerating machine oil, and 4,4'-thiobis (2-methyl-6-tert-butylphenol) is used as an additive in 0.2% by mass based on the total amount of refrigerating machine oil, p, p'-di-. A refrigerating machine oil was prepared by blending octyl-diphenylamine in an amount of 0.5% by mass based on the total amount of the refrigerating machine oil and glycerol monooleate in an amount of 0.2% by mass based on the total amount of the refrigerating machine oil.

Next, the following property measurement and evaluation tests were carried out for each of the refrigerating machine oils of Examples 5 to 10 and Comparative Examples 5 to 7. The results obtained are shown in Tables 3 and 4.

Regarding general properties (kinematic viscosity, flash point, pour point, acid value), JIS method (kinematic viscosity: K2283 (2000), flash point: K2265 (2007), pour point: K2269 (1987), acid value: K2501 ( The measurement was performed in accordance with 2003)), and the hue was measured in accordance with ASTM D156.

[Evaluation of thermochemical stability]
Based on Annex C (Chemical stability test method with refrigerant) of JIS K2211 (refrigerator oil), each refrigerating machine oil (water content is 1000 ppm for polyalkylene glycol in Examples and water content for mineral oils in Comparative Examples). 30 g of the mixture (adjusted to 30 ppm), 30 g of propane (R290), and a catalyst (iron, copper, and aluminum wires) were sealed in an autoclave, and then heated to 175 ° C. and held for 7 days for testing. After the test, the hue and acid value of the sample (refrigerator oil) were evaluated.

[Evaluation of required amount of refrigerant (air conditioner test)]
The capacity of the air conditioner in which 200 g of the mineral oil refrigerating machine oil of Comparative Example 5 and 350 g of propane (R290) were sealed in the integrated air conditioner was measured and used as a reference. Next, the amount of propane (R290) required to achieve the same cooling capacity was measured by sequentially using the refrigerating machine oils of Examples 5 to 10 and Comparative Examples 6 and 7 (initially 350 g and 200 g of refrigerating machine oil). Enclose and gradually remove from refrigeration cycle while measuring capacity).

The results obtained are shown in Table 3.

From Tables 3 and 4, in terms of thermal and chemical stability, the refrigerating machine oil of Example 5 does not contain any additives, so that there is some deterioration in hue and increase in acid value, but this is not a problem. You can see that. Examples 6 to 10 in which the additive is blended are good with no deterioration in hue and oxidation. According to the air conditioner test, it was found that the required amount of the refrigerant to be filled can be significantly reduced by using the refrigerating machine oil of the present invention. In Comparative Example 7, the thermal and chemical stability is at a level that does not cause any problem, but the kinematic viscosity is high. Therefore, since the viscous resistance is large, it is considered that the efficiency of the compressor is deteriorated, which is not preferable.

It was confirmed that the refrigerating machine oils of Examples 1 to 10 had a saturated solubility of propane in the refrigerating machine oil at 70 ° C. of 20% by mass or less. The saturated solubility of propane in refrigerating machine oil at 70 ° C. was based on the method described in WO 2005/095557.

As described above, according to the present invention, in the working medium for a refrigerant compression type refrigerating cycle apparatus containing a refrigerant containing a hydrocarbon having 1 to 8 carbon atoms and a refrigerating machine oil, the refrigerating machine oil has appropriate compatibility with the refrigerant. A working medium for a refrigerant compression refrigeration cycle device that achieves at least one of low viscosity and high thermal stability is provided. Further, according to the present invention, there is provided an operating medium capable of exhibiting good performance even if the amount of the refrigerant (refrigerant containing hydrocarbons having 1 to 8 carbon atoms) filled in the refrigeration cycle apparatus is small.

This application is based on Japanese Patent Application No. 2019-145695 filed on August 7, 2019, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

Refrigerants containing hydrocarbons with 1 to 8 carbon atoms and
The following general formula (1):
R 1- (OR 2 ) n- OH (1)
[However, R 1 is a linear or branched alkyl group having 1 to 8 carbon atoms, and OR 2 represents an oxyalkylene group having 2 carbon atoms and / or 3 carbon atoms, which is the same or different. Represents the number of added moles of the oxyalkylene group represented by OR 2 . ]
A refrigerating machine oil containing a polyalkylene glycol having an average molecular weight of 200 to 1000, represented by
Including
In the general formula (1), the OR 2 contains an oxypropylene group, and the oxypropylene group is 80 mol% or more based on the total number of moles of the OR 2 .
A working medium for a refrigerant compression refrigeration cycle device, wherein the content of the alkylene glycol having n of 1 in the general formula (1) is 3% by mass or less with respect to the total mass of the polyalkylene glycol.
The working medium for a refrigerant compression type refrigerating cycle apparatus according to claim 1, wherein the refrigerating machine oil has a kinematic viscosity of 1 mm 2 / s or more and 45 mm 2 / s or less at 40 ° C.
The working medium for a refrigerant compression type refrigeration cycle apparatus according to claim 1 or 2, wherein the polyalkylene glycol contains polypropylene glycol monobutyl ether.
The working medium for a refrigerant compression type refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the polyalkylene glycol is contained in an amount of 85% by mass or more based on the total mass of the refrigerating machine oil.
One or more additives selected from the group consisting of amine compounds, phenol compounds, and partial esters of polyhydric alcohols are contained in the refrigerating machine oil by 0.1 to 3.0 mass with respect to the total mass of the refrigerating machine oil. The operating medium for a refrigerant compression type refrigeration cycle apparatus according to any one of claims 1 to 4, which is contained in%.
The invention according to any one of claims 1 to 5, wherein when the vapor pressure of the refrigerant at 70 ° C. is 1.77 MPa, the saturated solubility of the refrigerant in the refrigerating machine oil at 70 ° C. is 20% by mass or less. Working medium for refrigerant compression type refrigeration cycle equipment.
A refrigeration cycle device using the working medium according to any one of claims 1 to 6.