Refrigerator oil composition and working fluid for refrigerator

Abstract

Provided are a refrigerating machine oil composition and a working fluid for a refrigerating machine, with which it is possible to reduce the amount of refrigerant dissolved while maintaining the same flowability and the like with respect to a hydrocarbon refrigerant as in the prior art. The refrigerator oil composition includes a base oil component (A) for a hydrocarbon refrigerant and having at least one configuration represented by general formula (I) as a base oil [Formula 1] # imgabs0 # (in the formula, R1 is a glyceryl group, a trimethylolpropyl group, a bis-trimethylolpropyl group, a pentaerythritol group, or a dipentaerythritol group, R2 is a hydrogen atom or a methyl group, m is a value set in accordance with R1 and is 3-6, and n is 2-11).

Description

Technical Field

[0001] The present invention relates to a refrigerating machine oil composition for a hydrocarbon refrigerant and a refrigerating machine working fluid containing the refrigerating machine oil composition and a hydrocarbon refrigerant. Background Art

[0002] Regarding various equipment and devices using refrigerants and refrigeration cycles, the use of fluorocarbon (HFC or HFO) refrigerants that have been used in the past is gradually being restricted in accordance with global warming control and chemical substance regulations. Prior to this trend, hydrocarbon refrigerants such as isobutane (R-600a) and propane (R-290) used in the first half of the 20th century were reviewed. In Japan, R-600a was used in household refrigerators in 2000 and has become the mainstream as a fluorine-free refrigerator.

[0003] In addition, with the support of Germany, China has also gradually started to study the application of R-290 to equipment with relatively small refrigerant packaging volume, such as small air conditioners. For example, in Patent Document 1, a refrigeration oil composition using a base oil with a specific structure is proposed for use as a propane refrigerant.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Chinese Patent No. 107353983 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] On the other hand, hydrocarbon refrigerants are difficult to use in applications such as air conditioners and industrial refrigerators where a large amount of refrigerant is required due to their strong flammability. In these applications, non-flammable or weakly flammable fluorinated hydrocarbon refrigerants are still the mainstream. Therefore, in order to ensure safety, refrigeration and air conditioning equipment manufacturers strongly desire to reduce the amount of refrigerant sealed in the equipment while promoting the expansion of hydrocarbon refrigerant applications. In other words, if the amount of refrigerant dissolved in the refrigeration oil is small, the corresponding amount of refrigerant packaging can be reduced, so refrigeration oil compositions in which hydrocarbon refrigerants are difficult to dissolve are sought.

[0009] The present invention is made in view of such a situation, and its purpose is to provide a refrigeration oil composition, which can maintain the same fluidity as before for hydrocarbon refrigerants while reducing the amount of refrigerant dissolved. In addition, the present invention aims to provide a working fluid for refrigerators with a lower amount of hydrocarbon refrigerants and improved safety.

[0010] Technical means for solving technical problems

[0011] In order to solve the above-mentioned technical problems, the present invention provides the following refrigeration oil composition (1).

[0012] (1) A refrigerating machine oil composition for a hydrocarbon refrigerant, characterized in that it comprises, as a base oil, a base oil component A composed of at least one of the following general formula (I):

[0013] [Formula 1]

[0014]

[0015] (Where R 1 is glyceryl, trimethylolpropyl, ditrimethylolpropyl, pentaerythritol or dipentaerythritol, R 2 is a hydrogen atom or a methyl group, m is a value set according to R1 and is 3 to 6, and n is 2 to 11).

[0016] Furthermore, preferred embodiments of the refrigerating machine oil composition of the present invention relate to the following (2) to (4).

[0017] (2) The refrigerating machine oil composition according to (1), characterized in that

[0018] The base oil component A is contained in an amount of 10 mass % or more of the total amount of the base oil.

[0019] (3) The refrigerating machine oil composition according to (1), characterized in that

[0020] The average molecular weight of the base oil component A is 300-2000.

[0021] (4) The refrigerating machine oil composition according to (1), characterized in that

[0022] The base oil includes the base oil component A and a base oil component B. The base oil component B is composed of at least one of the compounds represented by the following general formula (II).

[0023] [Formula 2]

[0024]

[0025] (wherein, R is a hydrogen atom or a methyl group, R 3 It is hydroxyl (HO-), CH3O-, C2H5O-, C3H7O-, or C4H9O-, and n is 6 to 33. )

[0026] Furthermore, in order to solve the above-mentioned technical problems, the present invention provides the following (5) working fluid for a refrigerator.

[0027] (5) A working fluid for a refrigerator, characterized in that:

[0028] A refrigerating machine oil composition according to any one of (1) to (4), and a hydrocarbon refrigerant.

[0029] Effects of the Invention

[0030] According to the refrigerating machine oil composition of the present invention, the amount of hydrocarbon refrigerant dissolved can be reduced while maintaining the performance such as fluidity as a refrigerating machine oil composition, and the safety is further improved.

[0031] In addition, the refrigerator working fluid of the present invention has high safety because it maintains fluidity as a refrigerator working fluid and contains less dissolved hydrocarbon refrigerant. Therefore, by using the refrigerator working fluid of the present invention, a refrigeration system using hydrocarbon refrigerant can be safely operated. DETAILED DESCRIPTION

[0032] Hereinafter, the present invention will be described in detail.

[0033] [Refrigerator oil composition]

[0034] The refrigerator oil composition of the present invention is for hydrocarbon refrigerants and contains, as a base oil, at least one base oil component A represented by the following general formula (I).

[0035] [Formula 3]

[0036]

[0037] It should be noted that R in formula (I) 1 is glyceryl, trimethylolpropyl, ditrimethylolpropyl, pentaerythritol or dipentaerythritol, R 2 is a hydrogen atom or a methyl group, m is a value set according to R1 and is 3 to 6, and n is 2 to 11. In addition, m corresponds to R 1 The number of hydroxyl groups (OH groups) present is preferably 3 to 4 from the viewpoint of low temperature fluidity.

[0038] That is, the base oil component A, the end R 1 It has three or more hydroxyl groups. This can reduce the amount of hydrocarbon refrigerants dissolved. In addition, the base oil component A can also be said to be a polyalkylene glycol using a trivalent or higher polyol as an initiator.

[0039] In order to obtain the base oil component A, R 1It can be synthesized by at least one of glycerol (HOCH2CH(OH)CH2OH), trimethylolpropane (CH3CH2C(CH2OH)3), di-trimethylolpropane ((CH3CH2)(CH2OH)2CCH2OCH2C(CH2CH3)(CH2OH)2), pentaerythritol (C(CH2OH)4), and dipentaerythritol ((CH2OH)3CCH2OCH2C(CH2OH)3).

[0040] The base oil component A preferably has an average molecular weight of 300 to 2,000, more preferably 400 to 1,500, and even more preferably 800 to 1,200, taking into account the fluidity of the base oil and the like.

[0041] The base oil component A may be used alone or as a mixture of two or more thereof depending on fluidity and the like.

[0042] The content of the base oil component A is preferably 10% by mass or more of the total amount of the base oil, more preferably 20% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of further reducing the compatibility with the hydrocarbon refrigerant. In addition, the upper limit of the content of the base oil component A is not particularly limited, but since the kinematic viscosity tends to increase as the content of the base oil component A increases, it is appropriately 80% by mass or less of the total amount of the base oil, preferably 60% by mass or less.

[0043] The base oil may be only the base oil component A, or may be a mixture of the base oil component A and other base oil components. The other base oil components are not limited as long as they are components used as base oils for hydrocarbon refrigerants, but for example, the base oil component B represented by the following general formula (II) is preferred.

[0044] [Formula 4]

[0045]

[0046] It should be noted that R in formula (II) is a hydrogen atom or a methyl group, 3 It is a hydroxyl group (HO-), CH3O-, C2H5O-, C3H7O-, or C4H9O-, and n is 6 to 33. In addition, n is more preferably 12 to 21 from the viewpoint of low temperature fluidity.

[0047] That is, the base oil component B is, as its chemical structure, a polyalkylene glycol having a hydroxyl group at one terminal or both terminals.

[0048] Examples of the polyalkylene glycol include polypropylene glycol, copolymers (random or block) of polyethylene glycol and polypropylene glycol, and polypropylene glycol starting from butanol. Furthermore, from the viewpoint of insulation properties, propylene glycol is more desirable than ethylene glycol.

[0049] In addition, the content of the base oil component B is suitably 90% by mass or less, preferably 80% by mass or less, and more preferably 60% by mass or less, based on the relationship with the content of the base oil component A. In addition, the lower limit of the content of the base oil component B is not particularly limited, but in relation to the content of the base oil component A, it is suitably 10% by mass or more, preferably 20% by mass or more, and more preferably 40% by mass or more, based on the total amount of the base oil.

[0050] In addition, various additives can be added to the base oil according to the purpose, as in the past. For example, demulsifiers, rust inhibitors, defoamers, antioxidants, acid scavengers, anti-wear agents, extreme pressure agents, oiliness agents, detergent dispersants, pour point depressants, viscosity index improvers, metal inert agents, etc. can be added alone or in combination of several.

[0051] The type of hydrocarbon refrigerant (ie, a refrigerant consisting only of carbon and hydrogen and having 1 or more carbon atoms) is not limited, but methane, ethane, ethylene, propane, propylene, n-butane, 2-methylpropane, and the like are preferred.

[0052] [Example]

[0053] Below, examples are given to further illustrate the present invention.

[0054] (Base oil ingredients)

[0055] The base oil components shown in Table 1 were prepared. That is, in the general formula (I), R 1 Glyceryl, R 2 The base oil component (PAG-A in the table) is methyl, n is 5.1, and R 1 Glyceryl, R 2 A base oil component with a methyl group and n=2 (PAG-B in the table). In addition, the average molecular weight of PAG-A is about 1000, and the average molecular weight of PAG-B is about 400. PAG-A and PAG-B are equivalent to base oil component A.

[0056] In addition, in the general formula (II), R 3 A base oil component (PAG-M in the table) in which R is a hydroxyl group (OH group), R is a methyl group, and n is 16.6. In addition, the average molecular weight of PAG-M is about 1000, which is equivalent to base oil component B.

[0057] The physical properties of each base oil component were investigated based on JIS and are shown in Table 1. In the examples described below, the physical property values ​​are also based on JIS.

[0058] [Table 1]

[0059] Table 1 Base oil composition and properties

[0060]

[0061] (Preparation of base oil)

[0062] The base oil components were mixed in the ratios shown in Table 2 to prepare trial base oils 1 to 6 (all examples) shown in Table 2. In addition, for comparison, only PAG-M was used as a comparative base oil. The physical properties of each trial base oil are recorded together in Table 2. In addition, "-" in Table 2 means that the component is not contained.

[0063] [Table 2]

[0064] Table 2 Base oil properties

[0065]

[0066] Regarding physical property values, refrigeration oil used in compressors with built-in electric motors, which is combined with hydrocarbon refrigerants such as propane with high electrical insulation, needs to have a volume resistivity of 1×10 8 Electrical insulation of Ω·cm or more. For example, the volume resistivity of R-290, a hydrocarbon refrigerant, is 1×10 13 Ω·cm, the volume resistivity of the refrigeration oil combined therein is required to be 1×10 8 Ω·cm or more. Any trial-produced base oil meets this requirement.

[0067] (Compatibility with hydrocarbon refrigerants)

[0068] The compatibility of the trial base oils 1 to 6 and the comparative base oil with R-290 as a hydrocarbon refrigerant was evaluated. The results are shown in Table 3, where the unit of the refrigerant concentration in the oil is "mass %". In addition, "-" in Table 3 means that the component is not contained.

[0069] [Table 3]

[0070] Table 3 Compatibility of trial base oil and hydrocarbon refrigerant

[0071]

[0072] As shown in Table 3, the amount of refrigerant dissolved at each temperature was reduced by using the prototype base oil compared to the case of using the comparative base oil.

[0073] From the above, it was verified that the amount of dissolved hydrocarbon refrigerant can be reduced compared with the related art by using a base oil containing the base oil component A according to the present invention.

[0074] (Solubility of Additives)

[0075] It was verified that in the trial-produced base oil, even if various additives widely added in the refrigerating machine oil composition in the past were added, the performance of the refrigerating machine oil composition did not change. That is, in the above-mentioned trial-produced base oil, phenolic antioxidants, epoxy acid scavengers, imide acid scavengers, phosphate ester extreme pressure agents, and silicone defoamers in the table were added to prepare the trial-produced oil, and the dissolution state of each additive in each trial-produced oil was observed with the eyes to investigate the physical properties of each trial-produced oil. The results are shown in Table 4, and the "○" in the column of the additive in the table indicates that the additive is dissolved in the trial-produced base oil.

[0076] [Table 4]

[0077] Table 4 Preparation and properties of trial refrigeration oil

[0078]

[0079] As shown in Table 4, it can be seen that even if the base oil component A is contained, it has no influence on the addition of various additives and can be used in the same manner as before.

[0080] (Thermal stability)

[0081] The thermal stability of the trial oil was verified under the following test conditions. The results are shown in Table 5, where "○" in the column of catalyst change indicates no change.

[0082] <Test conditions>

[0083] Test method: Sealed tube test (complying with JIS and ASHRAE methods)

[0084] Packaging volume: trial oil / R-290=1[mL] / 1[mL]

[0085] Catalyst: Fe, Cu and Al

[0086] Moisture: 100 [ppm] or less

[0087] Vacuum degree: 0.1[mmHg]

[0088] Temperature: 175[℃]

[0089] Period: 14 [days]

[0090] [Table 5]

[0091] Table 5 Chemical stability test results

[0092]

[0093] As shown in Table 5, it can be seen that even if the base oil component A is contained, the thermal stability does not decrease and the same use as in the related art is possible.

[0094] (Hydrolysis stability)

[0095] The hydrolysis stability of the trial oil was verified under the following test conditions. The results are shown in Table 6, where "○" in the column where the catalyst was changed means that there was no change.

[0096] <Test conditions>

[0097] Test method: Sealed tube test (complying with JIS and ASHRAE methods)

[0098] Packing volume: trial oil / R-290=8[g] / 0.6[g]

[0099] Catalyst: Fe, Cu and Al

[0100] Moisture: 500 [ppm]

[0101] Vacuum degree: 0.1[mmHg]

[0102] Temperature: 175[℃]

[0103] Period: 14 [days]

[0104] [Table 6]

[0105] Table 6 Hydrolysis stability test results

[0106]

[0107] As shown in Table 6, even if the base oil component A is included, the hydrolysis stability does not decrease and the product can be used in the same manner as in the related art.

[0108] As shown in the above examples, even if the base oil component A is contained, the physical properties as a refrigerating machine oil composition are not deteriorated and it can be used in the same manner as before, and the amount of hydrocarbon refrigerant used can be reduced, and safety can be further improved.

[0109] [Working fluid for refrigerator]

[0110] The present invention relates to a working fluid for a refrigerator comprising the above-mentioned refrigerator oil composition and a hydrocarbon refrigerant.

[0111] As the hydrocarbon refrigerant, methane, ethane, ethylene, propane, propylene, n-butane, 2-methylpropane, or the like is preferable.

[0112] Furthermore, according to the present invention, the amount of hydrocarbon refrigerant used can be further reduced, and the safety as a working fluid for a refrigerator can be further improved.

[0113] Above, various embodiments have been described, but it is needless to say that the present invention is not limited to the relevant examples. For those skilled in the art, it is obvious that various modifications or amendments can be thought of within the scope described in the protection scope, and it is necessary to understand that they certainly also belong to the technical scope of the present invention. In addition, in the scope that does not depart from the purpose of the invention, the various constituent elements in the above-mentioned embodiments can also be arbitrarily combined.

[0114] In addition, the present application is based on the Japanese patent application (Japanese Patent Application No. 2023-130112) filed on August 9, 2023, the contents of which are incorporated herein by reference.

Claims

1. A refrigerating machine oil composition, which is a refrigerating machine oil composition for hydrocarbon refrigerants, characterized in that: The base oil includes a base oil component A composed of at least one of the following general formula (I): [Formula 1] In the formula, R 1 is glyceryl, trimethylolpropyl, ditrimethylolpropyl, pentaerythritol or dipentaerythritol, R 2 is a hydrogen atom or a methyl group, m is a value set according to R1 and is 3 to 6, and n is 2 to 11.

2. The refrigerating machine oil composition according to claim 1, characterized in that The base oil component A is contained in an amount of 10 mass % or more of the total amount of the base oil.

3. The refrigerating machine oil composition according to claim 1, characterized in that The average molecular weight of the base oil component A is 300-2000.

4. The refrigerating machine oil composition according to claim 1, characterized in that The base oil comprises the base oil component A and the base oil component B, wherein the base oil component B is composed of at least one of the following general formula (II): [Formula 2] In the formula, R is a hydrogen atom or a methyl group, R 3 It is hydroxyl (HO-), CH3O-, C2H5O-, C3H7O-, or C4H9O-, and n is 6 to 33.

5. A working fluid for a refrigerator, characterized in that: include: The refrigeration oil composition according to any one of claims 1 to 4; as well as Hydrocarbon refrigerants.

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