JP6054495B2 - Working fluid composition for refrigerator - Google Patents

Description

  The present invention relates to a working fluid composition for a refrigerator, and more particularly to a working fluid composition for a refrigerator containing a refrigerant containing monofluoroethane (also referred to as “HFC-161” or “R161”).

  Due to the problem of ozone layer destruction in recent years, CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon), which have been used as refrigerants in conventional refrigeration equipment, are subject to regulation, and HFC (hydrofluorocarbon) is used as a refrigerant instead. It is being done.

  Among HFC refrigerants, HFC-134a, R407C, and R410A are standardly used as refrigerants for car air conditioners, refrigerators, and room air conditioners. However, these HFC refrigerants are becoming subject to regulation because of their high global warming potential (GWP) although their ozone depletion potential (ODP) is zero. Difluoromethane has been studied as one of the alternative candidates for these refrigerants, but the global warming potential is not sufficiently low, the boiling point is too low, and the thermodynamic characteristics cannot be applied to the current refrigeration system as it is, In addition, there is a problem that it is difficult to be compatible with lubricating oil (refrigeration machine oil) such as polyol ester and polyvinyl ether used in conventional HFC refrigerants. On the other hand, unsaturated fluorinated hydrocarbons are very small in both ODP and GWP, and are nonflammable depending on the structure. Among them, HFO-1234yf has a thermodynamic characteristic that is a measure of refrigerant performance as HFC-134a. Since it is substantially the same or more, use as a refrigerant | coolant is proposed (patent documents 1-3).

  In addition, as the first component, 1,1-difluoroethane (HFC-152a), 1,1,1-trifluoro-2-monofluoroethane (HFC-134a), 1,1,1-trifluoro-2,2- There has been proposed a working medium composed of 80% by mass or more of one or more first components selected from difluoroethane (HFC-125) and 20% by mass or less of carbon dioxide (R744) as the second component (Patent Document 4).

  In addition, hydrocarbons such as isobutane (R600a) and propane (R290) that are flammable but have an ODP of 0 and an extremely low GWP of about 3 have been studied (Patent Documents 5 to 7).

International Publication WO2004 / 037913 Pamphlet International Publication WO2005 / 105947 Pamphlet International Publication WO2009 / 057475 Pamphlet JP-A-10-265771 JP 2000-044937 A JP 2000-274360 A JP 2010-031728 A

  The problem with the refrigeration and air conditioning system is that the refrigerant has a low global warming potential (GWP), has little adverse effect on the environment, is difficult to burn and explode, can be used safely, and has thermodynamic characteristics suitable for the application. The chemical structure is simple and a large amount can be supplied at low cost. The characteristics of the system in which refrigerant and refrigerating machine oil coexist are mutually soluble (compatible), excellent in stability, and maintain an oil film that does not wear. Is to find a working fluid that satisfies all of the many properties of being lubricated.

  As described above, HFC-32 (GWP: 675), HFO-1234yf (GWP: 4), HFC-152a (GWP: 120), as the low-GWP next-generation refrigerant, which replaces the existing HFC refrigerant with a large GWP, Propane (R290, GWP: 3) and the like have been studied as promising candidates, but each has a problem.

  In the refrigerant circulation cycle of the refrigeration / air conditioning equipment, since the refrigeration oil that lubricates the refrigerant compressor circulates in the cycle together with the refrigerant, the refrigeration oil is required to have compatibility with the refrigerant. However, the refrigeration / air conditioning system using HFC-32 has a problem that it is difficult to be compatible with refrigeration oil. In refrigeration and air conditioning equipment, depending on the selection of the refrigeration oil used for the refrigerant, sufficient compatibility between the refrigerant and the refrigeration oil is not obtained, and the refrigeration oil discharged from the refrigerant compressor is placed at a low temperature in the cycle. It becomes easy to stay. As a result, the amount of oil in the refrigerant compressor decreases, causing problems due to wear due to poor lubrication and closing of an expansion mechanism such as a capillary that is a narrow tube having an inner diameter of 1 mm or less. Moreover, HFC-32 has a boiling point of −52 ° C., which is about 10 ° C. lower than the current refrigerant HCFC-22 used in room air conditioners, packaged air conditioners, etc., and the discharge temperature is higher at the same temperature. There is also a problem of thermodynamic characteristics that it is too high, and GWP is not sufficiently small as 675.

  In refrigeration and air conditioning systems using HFO-1234yf, which is an unsaturated fluorohydrocarbon and extremely small GWP, it is compatible with refrigeration machine oils such as polyol esters and ether compounds currently used in HFC, and can be applied. Has been considered. However, according to the study by the present inventors, since the unsaturated fluorinated hydrocarbon has an unstable double bond in the molecule, the problem in terms of stability is inferior in thermal and chemical stability. Became. HFO-1234yf has a boiling point of −25 ° C. and can be applied to the car air conditioner and refrigerator fields where HFC-134a having a boiling point of −26 ° C. is used. The high efficiency of HCFC-22 or the like in which the amount of refrigerant is used is not applicable to room air conditioners, packaged air conditioners, industrial refrigerators, etc., because the efficiency is too low.

  HFC-152a is a refrigerant with a small GWP and a good balance of properties, except that it is flammable. However, it has a boiling point of −25 ° C. and is applicable only to the field of HFC-134a because of its thermodynamic characteristics. Among the main fields where HFC-134a is used, in the refrigerator field where the refrigerant charge amount is small, switching to isobutane (R600a) having a small GWP of 3 is already in progress. However, isobutane also has a problem that it cannot be applied to uses with a large amount of refrigerant charge in terms of thermodynamic characteristics and safety.

  Propane has a boiling point of -42 ° C, GWP is very small, HCFC-22 and its alternative ODP is 0, and R410A, a mixed refrigerant with 50% by mass of HFC-32 and HFC-125, is used. Excellent refrigerant characteristics. However, it is highly flammable and highly explosive, and there are safety issues.

  In the case of a refrigerant composed of 80% by mass or more such as 1,1-difluoroethane as the first component and 20% by mass or less of carbon dioxide as the second component as described in Patent Document 4, the ODP is 0. Although there is GWP, it is not small enough.

  The present invention has been made in view of such circumstances, and can achieve compatibility, thermal / chemical stability, and lubricity at a high level in a highly efficient system with little adverse effect on the environment. An object is to provide a working fluid composition for a refrigerator.

  As a result of intensive studies to achieve the above object, the present inventors have used a refrigerant containing monofluoroethane (HFC-161) and a refrigerating machine oil based on a specific ester or ether as described above. The present inventors have found that the problem can be solved and have completed the present invention.

That is, the present invention includes a refrigerant containing monofluoroethane,
A refrigerating machine oil containing at least one selected from polyol esters, polyvinyl ethers and polyalkylene glycol compounds as a base oil, wherein the base oil has a carbon / oxygen molar ratio of 2.5 to 5.8;
The working fluid composition for refrigerators containing the is provided.

The refrigerant may further contain at least one selected from a compound represented by the following general formula (A) and carbon dioxide.
C _p H _q F _r (A)
[In formula, p shows the integer of 1-4, q shows the integer of 1-10, r shows the integer of 0-5. ]

  Further, when the refrigerant contains a compound represented by the general formula (A), examples of the compound include difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2 -At least one selected from tetrafluoroethane, pentafluoroethane, 1,3,3,3-tetrafluoropropene, 2,3,3,3-tetrafluoropropene, propane (R290) and isobutane (R600a) is preferable. .

  The mass ratio of the refrigerant to the refrigerating machine oil is preferably 90:10 to 30:70.

  The global warming potential of the refrigerant is preferably 300 or less.

  When the base oil contains a polyol ester having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less, preferred examples of the polyol ester include fatty acids having 4 to 9 carbon atoms and polyvalent acids having 4 to 12 carbon atoms. Mention may be made of polyol esters synthesized from alcohols.

  When the base oil contains a polyalkylene glycol having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less, preferred examples of the polyalkylene glycol compound include propylene oxide homopolymer chains or propylene oxide and ethylene oxide. Examples thereof include a compound having a copolymer chain and at least one of both ends of which is blocked with an ether bond.

［式中、Ｒ^１，Ｒ^２およびＲ^３は同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜８の炭化水素基を示し、Ｒ^４は炭素数１〜１０の二価の炭化水素基または炭素数２〜２０の二価のエーテル結合酸素含有炭化水素基を示し、Ｒ^５は炭素数１〜２０の炭化水素基を示し、ｍは前記ポリビニルエーテルについてのｍの平均値が０〜１０となるような数を示し、Ｒ^１〜Ｒ^５は構造単位毎に同一であっても異なっていてもよく、一の構造単位においてｍが２以上である場合には、複数のＲ^４Ｏは同一でも異なっていてもよい。］ When the base oil contains a polyvinyl ether having a carbon / oxygen molar ratio of 2.5 or more and 5.8 or less, as a preferred example of the polyvinyl ether, a polyvinyl ether having a structural unit represented by the following general formula (1) Can be mentioned.

[Wherein R ¹ , R ² and R ³ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴ represents a divalent carbon atom having 1 to 10 carbon atoms. A hydrogen group or a divalent ether-bonded oxygen-containing hydrocarbon group having 2 to 20 carbon atoms, R ⁵ represents a hydrocarbon group having 1 to 20 carbon atoms, and m is an average value of m for the polyvinyl ether is 0. And R ^{1 to} R ⁵ may be the same or different for each structural unit. When m is 2 or more in one structural unit, a plurality of R ⁴ O may be the same or different. ]

  According to the present invention, there is provided a working fluid composition for a refrigerator that can achieve compatibility, thermal / chemical stability, and lubricity at a high level in a highly efficient system with little adverse effect on the environment. Is done.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

The working fluid composition for a refrigerator according to this embodiment is
A refrigerant containing monofluoroethane;
A refrigerating machine oil containing at least one selected from polyol esters, polyvinyl ethers and polyalkylene glycol compounds as a base oil, wherein the base oil has a carbon / oxygen molar ratio of 2.5 to 5.8;
Containing.
_{C 2 H n F 6-n} (A)
[Wherein n represents 1 or 2. ]

  In the working fluid composition for a refrigerator according to this embodiment, the mixing ratio of the refrigerant and the refrigerator oil is not particularly limited, but the mass ratio of the refrigerant and the refrigerator oil is preferably 90:10 to 30:70, and more Preferably it is 80: 20-40: 60.

  Next, the components contained in the working fluid composition for refrigerators will be described in detail.

[Refrigerant]
The refrigerant in this embodiment contains monofluoroethane (HFC-161). Monofluoroethane has one fluorine in its molecule and exhibits characteristic properties.

  That is, first, in the field where HCFC-22 has been used as a refrigerant, propane (R290) is most suitable as a low GWP refrigerant because of its thermodynamic characteristics. However, since propane is highly flammable, there is a big problem in safety, and when coexisting with refrigerating machine oil, there is a problem that it is excessively dissolved in refrigerating machine oil and drastically lowers the viscosity of the oil and lowers lubricity.

  On the other hand, monofluoroethane has a GWP as small as 100 or less, a boiling point of −37 ° C., close to the boiling point of −41 ° C. of HCFC-22, has similar thermodynamic characteristics, and can be used alone as a refrigerant. Good mechanical properties, compatibility with refrigerating machine oil, and stability. In addition, although it is flammable, HFC-161 has a lower explosion limit of 5.0% by volume, compared with 2.1% by volume, which is the lower limit of explosion of propane. Refrigerant leakage is difficult to occur and it is much safer. The refrigerant concentration in the room hardly reaches 5.0% by volume. In addition, since fluorine is contained in the molecule, the amount dissolved in refrigerating machine oil is much less than that of propane, and the amount of refrigerant charge per refrigeration / air-conditioning device can be reduced. It is considered possible. Since the amount of the dissolved refrigeration oil in the coexisting refrigeration oil is small, the decrease in the viscosity of the refrigeration oil is small and the lubricity is advantageous, and there is no problem in stability because there is no double bond in the molecule.

In addition to monofluoroethane, the refrigerant in the present embodiment may further contain at least one selected from a compound represented by the following general formula (A) and carbon dioxide.
C _p H _q F _r (A)
[In formula, p shows the integer of 1-4, q shows the integer of 1-10, r shows the integer of 0-5. ]

  When the refrigerant in the present embodiment contains at least one selected from the compound represented by the general formula (A) and carbon dioxide, flammability derived from monofluoroethane can be reduced. Further, by adjusting the refrigerant composition, it is possible to easily and reliably adjust the thermodynamic characteristics of the refrigerant according to the purpose of use, which is effective in increasing the efficiency of the system.

  For preferred components combined with monofluoroethane, the boiling point, GWP, and flammability are listed in parentheses, and HFC-32 (-52 ° C., 675, slightly flammable), HFC-152a (−25 ° C., 120, Flammable), HFC-143a (-47 ° C, 4300, slightly flammable), HFC-134a (-26 ° C, 1300, nonflammable), HFC-125 (-49 ° C, 3400, nonflammable), HFO-1234ze (-19 ° C, 6, slightly flammable), HFO-1234yf (-29 ° C, 4, flammable), propane (-42 ° C, 3, flammable), isobutane (-12 ° C, 3, flammable) ), Carbon dioxide (-78 ° C., 1, nonflammability). Two or more of these components may be combined.

  For example, in order to improve the safety of the refrigerant (mixed refrigerant) in the present embodiment, a nonflammable refrigerant may be blended, but the nonflammable HFC refrigerant generally has a high GWP. Therefore, there is a method of balancing the characteristics by blending a slightly flammable refrigerant. In particular, since carbon dioxide is nonflammable and is as small as 1 as a GWP reference compound, blending in a range that does not affect thermodynamic properties is effective. In order to increase efficiency, a high-pressure refrigerant, that is, a refrigerant having a low boiling point, is blended. However, since propane is highly flammable, HFC-32, HFC-143a, and HFC-125 are candidates. .

  In order to reduce GWP, HFO-1234ze, HFO-1234yf, carbon dioxide, propane, and isobutane are preferable.

  In addition, when reducing the pressure of the mixed refrigerant for application to fields other than where HCFC-22 has been used, HFC-134a, HFO-1234ze having a boiling point higher than −30 ° C. A refrigerant having a relatively low pressure such as HFO-1234yf is selected.

  When the refrigerant in the present embodiment is a mixed refrigerant of monofluoroethane and the above components, the content ratio of monofluoroethane in the mixed refrigerant is preferably 50% by mass or more, and more preferably 60% by mass or more. preferable. Moreover, about GWP, it is preferable to set it as 300 or less from a viewpoint of global environment protection, 200 or less, and 150 or less are more preferable. The refrigerant mixture used in the present embodiment is preferably an azeotrope, but need not be an azeotrope as long as it has physical properties necessary as a refrigerant.

[Refrigerator oil]
The refrigerating machine oil according to the present embodiment contains at least one selected from polyol esters, polyvinyl ethers and polyalkylene glycol compounds as a base oil, and the carbon / oxygen molar ratio of the base oil is 2.5 or more and 5.8 or less. is there. Carbon and oxygen in the base oil can be quantitatively analyzed by a general elemental analysis method. For carbon analysis, there are a thermal conductivity method after conversion to carbon dioxide by combustion, a gas chromatography method, and the like. For oxygen analysis, a carbon reduction method in which carbon monoxide is quantitatively analyzed by carbon is generally used. -The Unteraucher method has been widely put into practical use.

  In addition, when the base oil is two or more kinds of mixed base oils, as long as the carbon / oxygen molar ratio of the mixed base oil is 2.5 or more and 5.8 or less, carbon / The oxygen molar ratio is not particularly limited, but the carbon / oxygen molar ratio of each of the polyol ester, polyvinyl ether, and polyalkylene glycol compound is preferably 2.5 or more and 5.8 or less. These preferable examples will be described later.

[Polyol ester]
The polyol ester is an ester synthesized from a polyhydric alcohol and a carboxylic acid, and the carbon / oxygen molar ratio is preferably 2.5 or more and 5.8 or less, more preferably 3.2 or more and 5.0 or less. More preferably, it is 4.0 or more and 5.0 or less. As the carboxylic acid, a fatty acid (monovalent aliphatic carboxylic acid), particularly a saturated fatty acid is preferably used, and the carbon number thereof is preferably 4 or more and 9 or less, particularly preferably 5 or more and 9 or less. The polyol ester may be a partial ester in which some of the hydroxyl groups of the polyhydric alcohol are not esterified and remain as hydroxyl groups, or may be a complete ester in which all the hydroxyl groups are esterified. A mixture of ester and complete ester may be used, but the hydroxyl value is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and most preferably 3 mgKOH / g or less.

[fatty acid]
(A) Of hydrofluoroethane, difluoromethane and 2,3,3,3-tetrafluoropropene represented by the above general formula (A), which is the main component of the refrigerant, difluoromethane having poor compatibility with refrigerating machine oil. When the proportion is high, for example, when the proportion of difluoromethane in the refrigerant is 40% by mass or more, among the fatty acids constituting the polyol ester, the proportion of branched fatty acids is 50 to 100 mol%, particularly 70 to 100 mol%. Furthermore, 90-100 mol% is preferable.

  Specific examples of branched fatty acids having 4 to 9 carbon atoms include branched butanoic acid, branched pentanoic acid, branched hexanoic acid, branched heptanoic acid, branched octanoic acid, and branched nonane. Examples include acids. More specifically, fatty acids having a branch at the α-position and / or β-position are preferred, and isobutanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-methyl Heptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid and the like are preferable, among which 2-ethylhexanoic acid and / or 3,5,5-trimethylhexanoic acid are most preferable. In addition, you may contain fatty acids other than C5-C9 branched fatty acid.

  (B) Among the main components of the refrigerant, the total content of 2,3,3,3-tetrafluoropropene is larger than the total content of hydrofluoroethane and difluoromethane represented by the general formula (A). In this case, since it becomes easy to be compatible with refrigerating machine oil, the proportion of linear fatty acid in the fatty acid is preferably 50 to 95 mol%, particularly 60 to 90 mol%, more preferably 70 to 85 mol%.

  Specific examples of the linear fatty acid having 4 to 9 carbon atoms include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid. Of these, pentanoic acid and / or heptanoic acid are particularly preferable, and a mixed acid of both is most preferable. The content of linear pentanoic acid is particularly preferably 30 mol% or more from the viewpoint of compatibility, and on the other hand, 50 mol% or less, particularly 45 mol% or less is particularly preferable from the viewpoint of hydrolysis stability. The heptanoic acid content is preferably 20 mol% or more, particularly 25 mol% or more, more preferably 30 mol% or more from the viewpoint of lubricity. On the other hand, it is 50 mol% or less, preferably 45 mol% or less, particularly from the viewpoint of hydrolysis stability. As the branched fatty acid other than the linear fatty acid, a branched fatty acid having 5 to 9 carbon atoms, particularly 2-ethylhexanoic acid and / or 3,5,5-trimethylhexanoic acid is preferable. The content of 3,5,5-trimethylhexanoic acid is particularly preferably 5 mol% or more, particularly preferably 10 mol% or more from the viewpoint of hydrolytic stability, and on the other hand, particularly from the viewpoint of compatibility and lubricity, 30 It is preferably not more than mol%, particularly preferably not more than 25%.

  As the preferable fatty acid in the case of (b), specifically, a linear pentanoic acid and a mixed acid of a linear heptanoic acid and 3,5,5-trimethylhexanoic acid are preferable, and this mixed acid is a linear acid. It is more preferable to contain 30-50 mol% of pentanoic acid, 20-50 mol% of linear heptanoic acid, and 5-30 mol% of 3,5,5-trimethylhexanoic acid.

[Polyhydric alcohol]
As the polyhydric alcohol constituting the polyol ester, a polyhydric alcohol having 2 to 6 hydroxyl groups is preferably used. As carbon number of a polyhydric alcohol, 4-12, especially 5-10 are preferable. Hindered alcohols such as neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, di- (trimethylol propane), tri- (trimethylol propane), pentaerythritol, di- (pentaerythritol) are preferred. Pentaerythritol or a mixed ester of pentaerythritol and di- (pentaerythritol) is most preferred because it is particularly excellent in compatibility with the refrigerant and hydrolytic stability.

[Polyvinyl ether]
The carbon / oxygen molar ratio of polyvinyl ether is preferably 2.5 or more and 5.8 or less, more preferably 3.2 or more and 5.8 or less, and further preferably 4.0 or more and 5.0 or less. If the carbon / oxygen molar ratio is less than this range, the hygroscopicity is high, and if it exceeds this range, the compatibility is lowered. The weight average molecular weight of polyvinyl ether is preferably 200 or more and 3000 or less, more preferably 500 or more and 1500 or less.

［式中、Ｒ^１，Ｒ^２およびＲ^３は同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜８の炭化水素基を示し、Ｒ^４は炭素数１〜１０の二価の炭化水素基または炭素数２〜２０の二価のエーテル結合酸素含有炭化水素基を示し、Ｒ^５は炭素数１〜２０の炭化水素基を示し、ｍは前記ポリビニルエーテルについてのｍの平均値が０〜１０となるような数を示し、Ｒ^１〜Ｒ^５は構造単位毎に同一であっても異なっていてもよく、一の構造単位においてｍが２以上である場合には、複数のＲ^４Ｏは同一でも異なっていてもよい。］ The polyvinyl ether preferably used in the present embodiment has a structural unit represented by the following general formula (1).

[Wherein R ¹ , R ² and R ³ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴ represents a divalent carbon atom having 1 to 10 carbon atoms. A hydrogen group or a divalent ether-bonded oxygen-containing hydrocarbon group having 2 to 20 carbon atoms, R ⁵ represents a hydrocarbon group having 1 to 20 carbon atoms, and m is an average value of m for the polyvinyl ether is 0. And R ^{1 to} R ⁵ may be the same or different for each structural unit. When m is 2 or more in one structural unit, a plurality of R ⁴ O may be the same or different. ]

In the general formula (1), at least one of R ¹ , R ² and R ³ is preferably a hydrogen atom, particularly preferably a hydrogen atom. M in the general formula (1) is 0 or more and 10 or less, particularly 0 or more and 5 or less, and more preferably 0. R ⁵ in the general formula (1) represents a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, a phenyl group, an aryl group, and an arylalkyl group, and an alkyl group, particularly an alkyl group having 1 to 5 carbon atoms is preferable.

  The polyvinyl ether according to this embodiment may be a homopolymer having the same structural unit represented by the general formula (1) or a copolymer composed of two or more structural units. However, the use of the copolymer has the effect of further improving the lubricity, insulation, hygroscopicity and the like while satisfying the compatibility. At this time, by selecting the kind of raw material monomer, the kind of initiator, and the ratio of the copolymer, the performance of the oil can be adjusted to the target level. Therefore, it is possible to freely obtain an oil agent that meets different requirements such as lubricity and compatibility depending on the type of compressor in the refrigeration system or the air conditioning system, the material of the lubrication part, the refrigeration capacity, the type of refrigerant, and the like. The copolymer may be a block copolymer or a random copolymer.

When the polyvinyl ether according to this embodiment is a copolymer, the copolymer is a structural unit represented by the general formula (1) and R ⁵ is an alkyl group having 1 to 3 carbon atoms (1-1 And a structural unit (1-2) represented by the general formula (1) and R ⁵ is an alkyl group having 3 to 20, preferably 3 to 10, more preferably 3 to 8 carbon atoms. It is preferable. As R ⁵ in the structural unit (1-1), an ethyl group is particularly preferable, and as R ^{5 in} the structural unit (1-2), an isobutyl group is particularly preferable. Furthermore, when the polyvinyl ether according to the present embodiment is a copolymer containing the structural units (1-1) and (1-2), the structural unit (1-1) and the structural unit (1-2) The molar ratio is preferably 5:95 to 95: 5, more preferably 20:80 to 90:10, and even more preferably 70:30 to 90:10. When the molar ratio deviates from the above range, the compatibility with the refrigerant becomes insufficient, and the hygroscopicity tends to increase.

［式中、Ｒ^６〜Ｒ^９は互いに同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜２０の炭化水素基を示す。］ The polyvinyl ether according to the present embodiment may be composed only of the structural unit represented by the general formula (1), but may further include a structural unit represented by the following general formula (2). It may be a polymer. In this case, the copolymer may be a block copolymer or a random copolymer.

[In formula, R < ⁶ > -R < ⁹ > may mutually be same or different, and shows a hydrogen atom or a C1-C20 hydrocarbon group, respectively. ]

［式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５およびｍは、それぞれ一般式（１）中のＲ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５およびｍと同一の定義内容を示す。］ [Terminal structure of polyvinyl ether]
The polyvinyl ether according to this embodiment can be produced by polymerization of a corresponding vinyl ether monomer and copolymerization of a corresponding hydrocarbon monomer having an olefinic double bond and a corresponding vinyl ether monomer. As the vinyl ether monomer corresponding to the structural unit represented by the general formula (1), a monomer represented by the following general formula (3) is preferable.

^{Wherein, R 1, R 2, R} 3, R 4, R 5 and m ^{is, R 1, R 2, R} 3, R 4, R 5 and m the same definition of each in the general formula (1) Show the contents. ]

［式中、Ｒ^１１、Ｒ^２１およびＲ^３１は互いに同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜８の炭化水素基を示し、Ｒ^４１は炭素数１〜１０の二価の炭化水素基または炭素数２〜２０の二価のエーテル結合酸素含有炭化水素基を示し、Ｒ^５１は炭素数１〜２０の炭化水素基を示し、ｍはポリビニルエーテルについてのｍの平均値が０〜１０となるような数を示し、ｍが２以上の場合には、複数のＲ^４１Ｏは同一でも異なっていてもよい。］

［式中、Ｒ^６１、Ｒ^７１、Ｒ^８１およびＲ^９１は互いに同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜２０の炭化水素基を示す。］

［式中、Ｒ^１２，Ｒ^２２およびＲ^３２は互いに同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜８の炭化水素基を示し、Ｒ^４２は炭素数１〜１０の二価の炭化水素基または炭素数２〜２０の二価のエーテル結合酸素含有炭化水素基を示し、Ｒ^５２は炭素数１〜２０の炭化水素基を示し、ｍはポリビニルエーテルについてのｍの平均値が０〜１０となるような数を示し、ｍが２以上の場合には、複数のＲ^４１Ｏは同一でも異なっていてもよい。］

［式中、Ｒ^６２、Ｒ^７２、Ｒ^８２およびＲ^９２は互いに同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜２０の炭化水素基を示す。］ As polyvinyl ether which concerns on this embodiment, what has the following terminal structures is suitable.
(A) One having one end represented by the general formula (4) or (5) and the other end represented by the general formula (6) or (7).

[Wherein R ¹¹ , R ²¹ and R ³¹ may be the same as or different from each other, each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴¹ is a divalent divalent having 1 to 10 carbon atoms. A hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group having 2 to 20 carbon atoms, R ⁵¹ represents a hydrocarbon group having 1 to 20 carbon atoms, and m is an average value of m for polyvinyl ether of 0 When m is 2 or more, a plurality of R ⁴¹ Os may be the same or different. ]

[Wherein, R ⁶¹ , R ⁷¹ , R ⁸¹ and R ⁹¹ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. ]

[Wherein R ¹² , R ²² and R ³² may be the same as or different from each other, each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴² is a divalent one having 1 to 10 carbon atoms. A hydrocarbon group or a divalent ether-bonded oxygen-containing hydrocarbon group having 2 to 20 carbon atoms, R ⁵² represents a hydrocarbon group having 1 to 20 carbon atoms, and m is an average value of m for polyvinyl ether of 0. When m is 2 or more, a plurality of R ⁴¹ Os may be the same or different. ]

[Wherein, R ⁶² , R ⁷² , R ⁸² and R ⁹² may be the same as or different from each other, and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. ]

［式中、Ｒ^１３、Ｒ^２３およびＲ^３３は互いに同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜８の炭化水素基を示す。］ (B) One having one end represented by the above general formula (4) or (5) and the other end represented by the following general formula (8).

[In formula, R < ¹³ >, R < ²³ > and R ^<33 > may mutually be same or different, and show a hydrogen atom or a C1-C8 hydrocarbon group, respectively. ]

Among such polyvinyl ether compounds, the following are particularly suitable as the main component of the refrigerating machine oil according to the present embodiment.
(1) One end is represented by the general formula (5) or (6), and the other end has a structure represented by the general formula (7) or (8), and R in the general formula (1) ¹ , R ² and R ³ are all hydrogen atoms, m is a number of 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, and R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms. thing.
(2) A structure having only the structural unit represented by the general formula (1), wherein one terminal is represented by the general formula (5) and the other terminal is represented by the general formula (7). R ¹ , R ² and R ³ in the general formula (1) are all hydrogen atoms, m is a number from 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, and R ⁵ is A hydrocarbon group having 1 to 20 carbon atoms.
(3) One end is represented by the general formula (5) or (6) and the other end is represented by the general formula (9), and R ¹ and R ² in the general formula (1) And R ³ is a hydrogen atom, m is a number of 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, and R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms.
(4) It has only the structural unit represented by the general formula (1), one end of which is represented by the general formula (III), and the other end is represented by the general formula (9). R ¹ , R ² and R ³ in the general formula (1) are all hydrogen atoms, m is a number from 0 to 4, R ⁴ is a divalent hydrocarbon group having 2 to ⁴ carbon atoms, and R ^5. Is a divalent hydrocarbon group having 1 to 20 carbon atoms and R ⁵ is a hydrocarbon group having 1 to 20 carbon atoms.
(5) above (1) a respective ~ (4), ^{R 5} in the general formula (1) is a structural unit with said ^{R 5} is a hydrocarbon group having 1 to 3 carbon atoms having 3 to 20 carbon atoms Those having a structural unit which is a hydrocarbon group.

[Production of polyvinyl ether]
The polyvinyl ether according to this embodiment can be produced by radical polymerization, cationic polymerization, radiation polymerization or the like of the above-described monomer. After completion of the polymerization reaction, a polyvinyl ether compound having the target structural unit represented by the general formula (1) can be obtained by subjecting to an ordinary separation / purification method as necessary.

  The polyvinyl ether according to the present embodiment needs to have a carbon / oxygen molar ratio in a predetermined range as described above, but by adjusting the carbon / oxygen molar ratio of the raw material monomer, the molar ratio is A range of polymers can be produced. That is, if the ratio of the monomer having a large carbon / oxygen molar ratio is large, a polymer having a large carbon / oxygen molar ratio is obtained, and if the ratio of the monomer having a small carbon / oxygen molar ratio is large, the polymer having a small carbon / oxygen molar ratio is obtained. Is obtained. In the case of copolymerizing a vinyl ether monomer and a hydrocarbon monomer having an olefinic double bond, a polymer having a carbon / oxygen molar ratio larger than the carbon / oxygen molar ratio of the vinyl ether monomer is obtained. Can be adjusted by the ratio of the hydrocarbon monomer having an olefinic double bond to be used and the number of carbon atoms.

  Moreover, in the manufacturing process of the polyvinyl ether represented by the general formula (1), a side reaction may occur and an unsaturated group such as an aryl group may be formed in the molecule. When an unsaturated group is formed in the polyvinyl ether molecule, the thermal stability of the polyvinyl ether itself is reduced, a polymer is produced and sludge is produced, or the antioxidant property (antioxidant property) is lowered. Phenomena such as generation of oxides are likely to occur. In particular, when a peroxide is generated, it decomposes to generate a compound having a carbonyl group, and the compound having a carbonyl group generates sludge, which easily causes capillary clogging. For this reason, as the polyvinyl ether according to the present embodiment, those having a low degree of unsaturation derived from an unsaturated group or the like are preferable, specifically, 0.04 meq / g or less is preferable, and 0.03 meq / g. Or less, and most preferably 0.02 meq / g or less. The peroxide value is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, and most preferably 1.0 meq / kg. Furthermore, the carbonyl value is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, and most preferably 20 ppm by weight or less.

  In the present invention, the degree of unsaturation, the peroxide value, and the carbonyl value refer to values measured by the standard oil analysis method established by the Japan Oil Chemists' Society. That is, the degree of unsaturation in the present invention refers to reacting a sample with a Wis solution (ICl-acetic acid solution), leaving it in the dark, and then reducing excess ICl to iodine and titrating the iodine with sodium thiosulfate. The iodine value is calculated by converting the iodine value into a vinyl equivalent (meq / g); in the present invention, the peroxide value is obtained by adding potassium iodide to a sample and converting the generated free iodine to thiol. Titration with sodium sulfate refers to a value (meq / kg) in which this free iodine is converted to the number of milliequivalents per 1 kg of the sample; the carbonyl value in the present invention refers to the action of 2,4-dinitrophenylhydrazine on the sample, A colored quinoid ion was produced, and the absorbance at 480 nm of this sample was measured. Based on a calibration curve obtained in advance using cinnamaldehyde as a standard substance, Say-converted value Le amount (wt ppm). The hydroxyl value is not particularly limited, but is desirably 10 mgKOH / g, preferably 5 mgKOH / g, and more preferably 3 mgKOH / g.

[Polyalkylene glycol compound]
The carbon / oxygen molar ratio of the polyalkylene glycol (PAG) compound according to this embodiment is preferably 2.5 or more and 5.8 or less, preferably 2.5 or more and 4.0 or less, and more preferably 2 7 or more and 3.5 or less. If the molar ratio is less than this range, the hygroscopicity is high and the electrical insulation is low, and if it exceeds this range, the compatibility is lowered. The weight average molecular weight of the polyalkylene glycol compound is preferably 200 or more and 3000 or less, more preferably 500 or more and 1500 or less.

[Structural unit of polyalkylene glycol]
Polyalkylene glycols have various chemical structures, but polyethylene glycol, polypropylene glycol, polybutylene glycol and the like are basic compounds, and unit structures are oxyethylene, oxypropylene, and oxybutylene, each of which is a monomer, ethylene oxide, It can be obtained by ring-opening polymerization using propylene oxide and butylene oxide as raw materials.

Examples of the polyalkylene glycol include a compound represented by the following general formula (1).
R ¹ -[(OR ² ) _f -OR ³ ] _g (1)
[In Formula (1), R ¹ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an acyl group having 2 to 10 carbon atoms, or a residue of a compound having 2 to 8 hydroxyl groups, and R ² represents the number of carbon atoms. Represents an alkylene group having 2 to 4, R ³ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group having 2 to 10 carbon atoms, f represents an integer of 1 to 80, and g represents 1 to 8 Represents an integer. ]

In the general formula (1), the alkyl group represented by R ¹ and R ³ may be linear, branched or cyclic. Preferably the carbon number of the said alkyl group is 1-10, More preferably, it is 1-6. When the number of carbon atoms in the alkyl group exceeds 10, the compatibility with the working medium tends to decrease.

Moreover, the alkyl group part of the acyl group represented by R ¹ and R ³ may be linear, branched, or cyclic. Carbon number of an acyl group becomes like this. Preferably it is 2-10, More preferably, it is 2-6. If the number of carbon atoms in the acyl group exceeds 10, the compatibility with the working medium may be reduced and phase separation may occur.

When the groups represented by R ¹ and R ³ are both alkyl groups or are both acyl groups, the groups represented by R ¹ and R ³ may be the same or different. Furthermore, when g is 2 or more, the groups represented by a plurality of R ¹ and R ³ in the same molecule may be the same or different.

When the group represented by R ¹ is a residue of a compound having 2 to 8 hydroxyl groups, this compound may be a chain or a cyclic one.

Among the polyalkylene glycols represented by the general formula (1), at least one of R ¹ and R ³ is preferably an alkyl group (more preferably an alkyl group having 1 to 4 carbon atoms), particularly methyl. The group is preferable from the viewpoint of compatibility with the working medium.

Furthermore, from the viewpoint of thermal and chemical stability, it is preferable that both R ¹ and R ³ are alkyl groups (more preferably, alkyl groups having 1 to 4 carbon atoms), and particularly that both are methyl groups. Is preferred.

From the viewpoint of ease of production and cost, it is preferable that either R ¹ or R ³ is an alkyl group (more preferably an alkyl group having 1 to 4 carbon atoms), and the other is a hydrogen atom, It is preferably a methyl group and the other is a hydrogen atom. From the viewpoint of lubricity and sludge solubility, it is preferable that both R ¹ and R ³ are hydrogen atoms.

R ² in the general formula (1) represents an alkylene group having 2 to 4 carbon atoms, and specific examples of such an alkylene group include an ethylene group, a propylene group, and a butylene group. Examples of the oxyalkylene group of the repeating unit represented by OR ² include an oxyethylene group, an oxypropylene group, and an oxybutylene group. The oxyalkylene groups in the same molecule may be the same, or two or more oxyalkylene groups may be included.

  Among the polyalkylene glycols represented by the general formula (1), from the viewpoints of compatibility with the working medium and viscosity-temperature characteristics, a copolymer containing an oxyethylene group (EO) and an oxypropylene group (PO) In such a case, the ratio of the oxyethylene group to the total of the oxyethylene group and the oxypropylene group (EO / (PO + EO)) is 0.1 to 0 in terms of baking load and viscosity-temperature characteristics. Is preferably in the range of .8, more preferably in the range of 0.3 to 0.6.

  In terms of hygroscopicity and heat / oxidation stability, the value of EO / (PO + EO) is preferably in the range of 0 to 0.5, more preferably in the range of 0 to 0.2, and 0 ( That is, a propylene oxide homopolymer) is most preferable.

F of the general formula (1) represents the repetition number of the oxyalkylene group OR ² (degree of polymerization) is an integer of 1 to 80. Moreover, g is an integer of 1-8. For example, when R ¹ is an alkyl group or an acyl group, g is 1. When R ¹ is a residue of a compound having 2 to 8 hydroxyl groups, g is the number of hydroxyl groups that the compound has.

  In addition, the product of f and g (f × g) is not particularly limited, but in order to satisfy the required performance as the above-described lubricating oil for a refrigerator in a balanced manner, the average value of f × g is 6 to 80. It is preferable to do so.

  The number average molecular weight of the polyalkylene glycol represented by the general formula (1) is preferably 500 to 3000, more preferably 600 to 2000, more preferably 600 to 1500, and n is the number average molecular weight of the polyalkylene glycol. It is preferable that the number satisfies the above conditions. When the number average molecular weight of the polyalkylene glycol is too low, the lubricity in the presence of the refrigerant is insufficient. On the other hand, when the number average molecular weight is too high, the composition range showing compatibility with the refrigerant under low temperature conditions is narrowed, and the refrigerant compressor is poorly lubricated and heat exchange in the evaporator is liable to occur.

  The hydroxyl value of the polyalkylene glycol is not particularly limited, but is desirably 100 mgKOH / g or less, preferably 50 mgKOH / g or less, more preferably 30 mgKOH / g or less, and most preferably 10 mgKOH / g or less.

The polyalkylene glycol according to the present embodiment can be synthesized using a conventionally known method (“alkylene oxide polymer”, Mitsuta Shibata et al., Kaibundo, issued 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)) by addition polymerization of one or more predetermined alkylene oxide to, etherified or further terminal hydroxyl group By esterification, the polyalkylene glycol represented by the general formula (1) is obtained. When two or more different alkylene oxides are used in the above production process, the resulting polyalkylene glycol may be either a random copolymer or a block copolymer, but more oxidative stability and lubricity. The block copolymer is preferable because it tends to be excellent in the temperature, and the random copolymer is preferable because it tends to be excellent in low-temperature fluidity.

The kinematic viscosity at 100 ° C. of the polyalkylene glycol according to this embodiment is preferably 5 to 20 mm ² / s, preferably 6 to 18 mm ² / s, more preferably 7 to 16 mm ² / s, and still more preferably 8 ˜15 mm ² / s, most preferably 10 to 15 mm ² / s. When the kinematic viscosity at 100 ° C. is less than the lower limit, the lubricity in the presence of the refrigerant becomes insufficient. On the other hand, when the upper limit is exceeded, the composition range showing compatibility with the refrigerant becomes narrow, and Machine lubrication and heat exchange in the evaporator are likely to be hindered. Moreover, kinematic viscosity at 40 ° C. of the polyalkylene glycol is preferably a kinematic viscosity at 40 ° C. is 10 to 200 mm ² / s, more preferably 20 to 150 mm ² / s. Tend kinematic viscosity 10mm sealability is less than 2 / ^s lubricity and compressor is reduced at 40 ° C., also exceeds 200 mm 2 / ^s, compatibility with the refrigerant at low temperature The composition range showing the above becomes narrow, and the lubrication failure of the refrigerant compressor and the heat exchange in the evaporator tend to be hindered.

  Moreover, the pour point of the polyalkylene glycol represented by the general formula (1) is preferably −10 ° C. or less, and more preferably −20 to −50 ° C. When a polyalkylene glycol having a pour point of −10 ° C. or higher is used, the refrigerating machine oil tends to solidify in the refrigerant circulation system at low temperatures.

  Further, in the production process of the polyalkylene glycol represented by the general formula (1), an alkylene oxide such as propylene oxide may cause a side reaction to form an unsaturated group such as an aryl group in the molecule. When an unsaturated group is formed in the polyalkylene glycol molecule, the thermal stability of the polyalkylene glycol itself is reduced, a polymer is produced and sludge is produced, or the antioxidant property (antioxidant property) is lowered. Therefore, a phenomenon such as generation of peroxide is likely to occur. In particular, when a peroxide is generated, it decomposes to generate a compound having a carbonyl group, and the compound having a carbonyl group generates sludge, which easily causes capillary clogging.

  Therefore, as the polyalkylene glycol according to the present embodiment, those having a low degree of unsaturation derived from an unsaturated group or the like are preferable, specifically 0.04 meq / g or less, preferably 0.03 meq / g. Or less, and most preferably 0.02 meq / g or less. The peroxide value is preferably 10.0 meq / kg or less, more preferably 5.0 meq / kg or less, and most preferably 1.0 meq / kg. Furthermore, the carbonyl value is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less, and most preferably 20 ppm by weight or less.

  In this embodiment, in order to obtain a polyalkylene glycol having a low degree of unsaturation, peroxide value, and carbonyl value, the reaction temperature when reacting propylene oxide is 120 ° C. or lower (more preferably 110 ° C. or lower). Is preferred. In addition, if an alkali catalyst is used in the production, the use of an inorganic adsorbent, such as activated carbon, activated clay, bentonite, dolomite, aluminosilicate, etc., to remove it may reduce the degree of unsaturation. Can do. Further, when the polyalkylene glycol is produced or used, contact with oxygen is avoided as much as possible, and an increase in the peroxide value or carbonyl value can also be prevented by adding an antioxidant.

  The polyalkylene glycol compound according to this embodiment is required to have a carbon / oxygen molar ratio in a predetermined range. By selecting and adjusting the type and mixing ratio of raw material monomers, the molar ratio is within the above range. Can be produced.

  In order for the content of polyol ester, polyvinyl ether or polyalkylene compound in refrigerating machine oil to be excellent in characteristics required for refrigerating machine oil such as lubricity, compatibility, thermal / chemical stability, and electrical insulation, refrigerating machine oil The total amount is preferably 80% by mass or more, particularly 90% by mass or more based on the total amount. As the base oil, in addition to the polyol ester, polyvinyl ether and polyalkylene glycol compound described later, mineral oil, olefin polymer, naphthalene compound, hydrocarbon oil such as alkylbenzene, and carbonate, ketone, polyphenyl ether, silicone, polysiloxane, A synthetic oil containing oxygen such as perfluoroether may be used in combination. Among the above, carbonates and ketones are preferably used as the synthetic oil containing oxygen.

The kinematic viscosity of the refrigerating machine oil is not particularly limited, but the kinematic viscosity at 40 ° C. is preferably 3 to 1000 mm ² / s, more preferably 4 to 500 mm ² / s, and most preferably 5 to 400 mm ² / s. it can. The kinematic viscosity at 100 ° C. is preferably 1 to 100 mm ² / s, more preferably ² to 50 mm ² / s.

The volume resistivity of the refrigerating machine oil is not particularly limited, but is preferably 1.0 × 10 ⁹ Ω · m or more, more preferably 1.0 × 10 ¹⁰ Ω · m or more, and most preferably 1.0 × 10 ¹¹ Ω · m. m or more. In particular, when it is used for a hermetic refrigerator, high electrical insulation tends to be required. In the present invention, the volume resistivity means a value at 25 ° C. measured in accordance with JIS C 2101 “Electrical insulating oil test method”.

  The water content of the refrigerating machine oil is not particularly limited, but can be preferably 200 ppm or less, more preferably 100 ppm or less, and most preferably 50 ppm or less based on the total amount of the refrigerating machine oil. In particular, when it is used for a hermetic type refrigerator, the moisture content is required to be small from the viewpoint of the influence on the thermal / chemical stability and electrical insulation of the refrigerator oil.

  The acid value of the refrigerating machine oil is not particularly limited, but is preferable in order to prevent corrosion of the metal used in the refrigerating machine or the piping and to prevent the decomposition of the ester contained in the refrigerating machine oil according to the present embodiment. May be 0.1 mgKOH / g or less, more preferably 0.05 mgKOH / g or less. In addition, in this invention, an acid value means the acid value measured based on JISK2501 "Petroleum products and lubricating oil-neutralization value test method".

  The ash content of the refrigerating machine oil is not particularly limited, but in order to increase the thermal and chemical stability of the refrigerating machine oil according to the present embodiment and suppress the generation of sludge and the like, the ash content is preferably 100 ppm or less, more preferably 50 ppm or less. . In the present invention, the ash means the value of ash measured in accordance with JIS K2272 “Testing method for ash and sulfated ash of crude oil and petroleum products”.

  The working fluid composition for a refrigerator according to this embodiment can be used in a form in which various additives are further blended as necessary. In the following description, the additive content is shown based on the total amount of the refrigerating machine oil composition, but the content of these components in the refrigerating machine fluid composition is based on the total amount of the refrigerating machine oil composition, The content is preferably 5% by mass or less, and particularly preferably 2% by mass or less.

  In order to further improve the wear resistance and load resistance of the working fluid composition for a refrigerator according to this embodiment, phosphoric acid ester, acidic phosphoric acid ester, thiophosphoric acid ester, amine salt of acidic phosphoric acid ester, chlorination At least one phosphorus compound selected from the group consisting of phosphoric acid esters and phosphorous acid esters can be blended. These phosphorus compounds are esters of phosphoric acid or phosphorous acid with alkanols and polyether type alcohols or derivatives thereof.

  In addition, the working fluid composition for a refrigerator according to the present embodiment has a phenyl glycidyl ether type epoxy compound, an alkyl glycidyl ether type epoxy compound, a glycidyl ester type epoxy compound, in order to further improve its thermal and chemical stability. It can contain at least one epoxy compound selected from allyl oxirane compounds, alkyl oxirane compounds, alicyclic epoxy compounds, epoxidized fatty acid monoesters and epoxidized vegetable oils.

  In addition, the working fluid composition for a refrigerator according to the present embodiment can contain a conventionally known additive for refrigerator oil as necessary in order to further enhance the performance. Examples of such additives include phenolic antioxidants such as di-tert-butyl-p-cresol and bisphenol A, phenyl-α-naphthylamine, N, N-di (2-naphthyl) -p-phenylenediamine, and the like. Amine-based antioxidants, anti-wear agents such as zinc dithiophosphate, extreme pressure agents such as chlorinated paraffin and sulfur compounds, oil-based agents such as fatty acids, antifoaming agents such as silicones, metal inertness such as benzotriazole Agents, viscosity index improvers, pour point depressants, detergent dispersants and the like. These additives may be used individually by 1 type, and may be used in combination of 2 or more type.

  The working fluid composition for a refrigerator according to this embodiment is preferably used for a room air conditioner, a refrigerator, or an open or sealed car air conditioner having a reciprocating or rotating hermetic compressor. Moreover, the working fluid composition for refrigeration machine and the refrigeration oil according to the present embodiment are preferably used for a dehumidifier, a water heater, a freezer, a refrigerated warehouse, a vending machine, a showcase, a cooling device for a chemical plant, and the like. Furthermore, the working fluid composition for refrigerating machine and the refrigerating machine oil according to this embodiment are also preferably used for those having a centrifugal compressor.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Refrigerator oil]
First, the base oils 1-4 shown below are di-ter. Refrigerating machine oils 1 to 4 were prepared by adding 0.1% by mass of -butyl-p-cresol (DBPC). Table 1 shows various properties of the refrigerating machine oils 1 to 4.
[Base oil]
Base oil 1: ester of mixed fatty acid (mixing ratio (molar ratio): 50/50) of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid and pentaerythritol. Carbon / oxygen molar ratio: 4.8
Base oil 2: ester of mixed fatty acid (mixing ratio (molar ratio): 40/40/20) of n-pentanoic acid, n-heptanoic acid and 3,5,5-trimethylhexanoic acid and pentaerythritol. Carbon / oxygen molar ratio: 3.3
Base oil 3: Copolymer of ethyl vinyl ether and isobutyl vinyl ether (ethyl vinyl ether / isobutyl vinyl ether = 7/1 (molar ratio). Weight average molecular weight: 910, carbon / oxygen molar ratio: 4.3
Base oil 4: A compound obtained by methyl etherifying both ends of polypropylene glycol. Weight average molecular weight: 1100, carbon / oxygen molar ratio: 2.9
Base oil 5: a compound of polyoxyethylene glycol and polyoxypropylene glycol, which is methyl etherified at one end. Weight average molecular weight: 1700, carbon / oxygen molar ratio: 2.7

[Examples 1-11, Comparative Examples 1-9]
In Examples 1-11 and Comparative Examples 1-9, the evaluation shown below about the working fluid composition for refrigerators which combined either of said refrigerator oil 1-4 and the refrigerant | coolant shown in Tables 2-4, respectively. The test was conducted. In addition, as will be described later, the mass ratio between the refrigerant and the refrigerating machine oil in the working fluid composition for the refrigerating machine was changed for each test.

As a refrigerant, in the examples, HFC-161 alone or HFC-161 is considered in consideration of overall characteristics, and is not highly flammable or flammable, but has a relatively small GWP HFC-134a, HFC-32, HFO Mixed refrigerants A, B, and C in which −1234yf and carbon dioxide (R744) were blended so that the GWP was 300 or less were used. In addition, since the fixed value of HFC-161 was not announced about GWP, it calculated using 100 which is the maximum value.
In the comparative examples, HFC-32 and HFO-1234yf, which are promising candidates, were used as new refrigerants based on the GWP value, combustibility, and thermodynamic characteristics.
[Refrigerant]
HFC-161: Monofluoroethane (GWP: about 100)
HFC-134a: 1,1,1,2-tetrafluoroethane (GWP: 1300)
HFC-32: Difluoromethane (GWP: 675)
HFO-1234yf: 2,3,3,3-tetrafluoropropene (GWP: 4)
Mixed refrigerant A: HFC-161 / HFC-134a = 85/15 (mass ratio, GWP: 280)
Mixed refrigerant B: HFC-161 / HFC-32 / R744 = 60/20/20 (mass ratio, GWP: 195)
Mixed refrigerant C: HFC-161 / HFO-1234yf = 60/40 (mass ratio, GWP: 62)

  Next, the following evaluation tests were performed on the working fluid compositions for refrigerators of Examples 1 to 11 and Comparative Examples 1 to 9. The results are shown in Tables 2-4.

[Compatibility evaluation]
In accordance with JIS-K-2211 “Refrigerating machine oil” “Compatibility test method with refrigerant”, 2 g of refrigerating machine oil is blended with 18 g of each of the above refrigerants including mixed refrigerant, and the refrigerant and refrigerating machine oil are at 0 ° C. It was observed whether they were dissolved in each other. The obtained results are shown in Tables 2-4. In the table, “compatible” means that the refrigerant and the refrigerating machine oil are dissolved in each other, and “separation” means that the refrigerant and the refrigerating machine oil are separated into two layers.

[Evaluation of thermal and chemical stability]
In accordance with JIS-K-2211, 1 g of refrigerating machine oil (initial hue L0.5) whose water content is adjusted to 100 ppm or less, 1 g of the above-mentioned various refrigerants, and catalysts (iron, copper, and aluminum wires) in a glass tube After sealing, it was placed in an iron protective tube, heated to 175 ° C. and held for 1 week for testing. After the test, the hue of the refrigerating machine oil and the color change of the catalyst were evaluated. The hue was evaluated according to ASTM D156. Further, the color change of the catalyst was visually observed for the appearance, and it was evaluated whether it corresponded to no change, no gloss, or blackening. In the case of no gloss and blackening, it can be said that the mixed liquid of the refrigerating machine oil and the refrigerant, that is, the working fluid is deteriorated. The obtained results are shown in Tables 2-4.

  The present invention is a working fluid composition used in a refrigeration / air conditioner in which a refrigerant containing HFC-161 is used, and includes a compressor, a condenser, a throttle device, an evaporator, and the like, and the refrigerant is between them. Refrigeration system with high cooling efficiency that circulates, and can be used as working fluid for refrigeration / air conditioners that have compressors such as rotary type, swing type, scroll type, reciprocating type compressor, etc., room air conditioner, package It can be suitably used in the fields of air conditioners, industrial refrigerators, refrigerators, car air conditioners and the like.

Claims (5)

A refrigerant consisting only of monofluoroethane , or difluoromethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane, propane (R290), A refrigerant consisting only of a mixture of at least one selected from isobutane (R600a) and carbon dioxide and monofluoroethane ;
A refrigerating machine oil containing polyvinyl ether as a base oil, wherein the base oil has a carbon / oxygen molar ratio of 2.5 to 5.8;
Containing
The working fluid composition for refrigerators whose kinematic viscosity in 100 degreeC of the said refrigerator oil is 1-100 mm < ² > / s. The working fluid composition for a refrigerator according to claim 1 , wherein a mass ratio of the refrigerant and the refrigerator oil is 90:10 to 30:70. The working fluid composition for a refrigerator according to claim 1 or 2 , wherein the refrigerant has a global warming potential of 300 or less. The working fluid composition for a refrigerator according to any one of claims 1 to 3 , wherein the polyvinyl ether is a polyvinyl ether having a structural unit represented by the following general formula (1).

[Wherein R ¹ , R ² and R ³ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R ⁴ represents a divalent carbon atom having 1 to 10 carbon atoms. A hydrogen group or a divalent ether-bonded oxygen-containing hydrocarbon group having 2 to 20 carbon atoms, R ⁵ represents a hydrocarbon group having 1 to 20 carbon atoms, and m is an average value of m for the polyvinyl ether is 0. And R ^{1 to} R ⁵ may be the same or different for each structural unit. When m is 2 or more in one structural unit, a plurality of R ⁴ O may be the same or different. ] The working fluid composition for a refrigerating machine according to any one of claims 1 to 4 , wherein the refrigerating machine oil has a kinematic viscosity at 40 ° C of 3 to 1000 mm ² / s.