Refrigerator oil composition and working fluid for refrigerating machine

Abstract

To provide a refrigerator oil composition and a working fluid for a refrigerating machine that can maintain fluidity and the like equivalent to conventional ones while reducing the amount of refrigerant dissolution with respect to hydrocarbon refrigerants.SOLUTION: The refrigerator oil composition for hydrocarbon refrigerants comprises a base oil component A consisting of at least one compound represented by the following general formula (I). The general formula (I) is represented by R1[(CH2-CHR2-O)nH]m, where R1 is a glyceryl group, a trimethylolpropyl group, a ditrimethylolpropyl group, a pentaerythritol group, or a dipentaerythritol group, R2 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.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In equipment and devices for various applications that use refrigerants and refrigeration cycles, the use of traditional fluorocarbon (HFC and HFO) refrigerants is being restricted due to global warming prevention and chemical substance regulations. Ahead of this trend, hydrocarbon refrigerants such as isobutane (R-600a) and propane (R-290), which were used in the first half of the 20th century, are being reconsidered. In Japan, R-600a was adopted for home refrigerators in 2000, and is now the mainstream of non-fluorocarbon refrigerators.

[0003] In addition, China, with the backing of Germany, has begun to consider the application of R-290 to devices with a relatively small amount of refrigerant, such as small air conditioners. For example, Patent Document 1 proposes a refrigeration oil composition using a base oil with a specific structure for a propane refrigerant. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent No. 107353983 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, since hydrocarbon refrigerants are highly flammable, they are difficult to apply to applications requiring a large amount of refrigerant, such as air conditioners and industrial freezers, and non-flammable or low-flammable fluorohydrocarbon refrigerants are still the mainstream for these applications. Therefore, in order to expand the application of hydrocarbon refrigerants, refrigeration and air conditioning equipment manufacturers have a strong desire to reduce the amount of refrigerant charged into the equipment as much as possible to ensure safety. In other words, if less refrigerant dissolves in the refrigeration oil, the amount of refrigerant charged can be reduced accordingly, so there is a demand for a refrigeration oil composition in which hydrocarbon refrigerants are less likely to dissolve.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a refrigerating machine oil composition that can reduce the amount of refrigerant dissolved in a hydrocarbon refrigerant while maintaining the same fluidity and other properties as conventional refrigerants. Another aim of the present invention is to provide a working fluid for a refrigerating machine that has a smaller amount of hydrocarbon refrigerant and is therefore safer. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a refrigerator oil composition as described below in (1).

[0008] (1) A refrigerating machine oil composition for use with a hydrocarbon refrigerant, comprising as a base oil at least one base oil component A represented by the following general formula (I):

[0009] [ka] (In the formula, R 1 is a glyceryl group, a trimethylolpropyl group, a ditrimethylolpropyl group, a pentaerythritol group, or a dipentaerythritol group; R 2 is a hydrogen atom or a methyl group, m is 3 to 6, and n is 2 to 11.

[0010] Further, preferred embodiments of the present invention relating to the refrigerating machine oil composition relate to the following (2) to (4).

[0011] (2) The refrigerating machine oil composition according to (1), characterized in that the base oil component A is contained in an amount of 10 mass % or more based on the total amount of base oils.

[0012] (3) The refrigerator oil composition according to (1), wherein the base oil component A has an average molecular weight of 300 to 2,000.

[0013] (4) The refrigerating machine oil composition according to (1), characterized in that the base oil comprises the base oil component A and at least one base oil component B represented by the following general formula (II):

[0014] [ka] (In the formula, R is a hydrogen atom or a methyl group, and R 3 is a hydroxyl group (HO-), CH3O-, C2H5O-, C3H7O-, or C4H9O-, and n is 6 to 33.

[0015] In order to solve the above problems, the present invention provides a working fluid for a refrigerating machine as described below in (5).

[0016] (5) A working fluid for a refrigerating machine, comprising the refrigerating machine oil composition according to any one of (1) to (4) above and a hydrocarbon refrigerant. Effect of the Invention

[0017] According to the refrigerating machine oil composition of the present invention, the amount of dissolved hydrocarbon refrigerant can be reduced while maintaining the performance such as fluidity of the refrigerating machine oil composition, and thus the refrigerating machine oil composition is more safe.

[0018] In addition, the working fluid for a refrigeration machine of the present invention maintains its fluidity as a working fluid for a refrigeration machine while dissolving a small amount of a hydrocarbon refrigerant, making it highly safe. Therefore, by using the working fluid for a refrigeration machine of the present invention, a refrigeration / chilling system using a hydrocarbon refrigerant can be operated safely. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention will be described in detail below.

[0020] [Refrigerating machine oil composition] The refrigerating oil composition of the present invention is for use with hydrocarbon refrigerants and contains, as a base oil, at least one type of base oil component A represented by the following general formula (I).

[0021] [ka]

[0022] In addition, R in formula (I) 1 is a glyceryl group, a trimethylolpropyl group, a ditrimethylolpropyl group, a pentaerythritol group, or a dipentaerythritol group; R 2 is a hydrogen atom or a methyl group, m is 3 to 6, and n is 2 to 11. 1 This corresponds to the number of hydroxyl groups (OH groups) possessed by the copolymer, and from the viewpoint of low-temperature fluidity, 3 to 4 is preferable.

[0023] That is, the base oil component A has a terminal R 1 has three or more hydroxyl groups. This makes it possible to reduce the amount of hydrocarbon refrigerant dissolved. The base oil component A can also be called a polyalkylene glycol using a trihydric or higher polyhydric alcohol as an initiator.

[0024] In order to obtain the base oil component A, the initiator R 1 The synthesis can be carried out using at least one of glycerin (HOCH2CH(OH)CH2OH), trimethylolpropane (CH3CH2C(CH2OH)3), ditrimethylolpropane ((CH3CH2)(CH2OH)2CCH2OCH2C(CH2CH3)(CH2OH)2), pentaerythritol (C(CH2OH)4), and dipentaerythritol ((CH2OH)3CCH2OCH2C(CH2OH)3).

[0025] Considering the flowability of the base oil, the base oil component A preferably has an average molecular weight of 300-2000, more preferably 400-1500, and even more preferably 800-1200.

[0026] The base oil component A may be used alone or in the form of a mixture of two or more kinds depending on the flowability and other properties.

[0027] From the viewpoint of further reducing the compatibility with hydrocarbon refrigerants, the content of base oil component A is preferably 10% by mass or more of the total amount of base oil, more preferably 20% by mass or more, and even more preferably 40% by mass or more. There is no particular upper limit to the content of base oil component A, but since the kinetic viscosity tends to increase with an increase in the content of base oil component A, it is appropriate that the content is 80% by mass or less, preferably 60% by mass or less of the total amount of base oil.

[0028] 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. There are no limitations on the other base oil components as long as they are used as base oils for hydrocarbon refrigerants, but for example, the base oil component B represented by the following general formula (II) is suitable.

[0029] [ka]

[0030] In the formula (II), R is a hydrogen atom or a methyl group, and R 3 is a hydroxyl group (HO-), CH3O-, C2H5O-, C3H7O-, or C4H9O-, and n is an integer of 6 to 33. In addition, n is more preferably an integer of 12 to 21 from the viewpoint of low-temperature fluidity.

[0031] That is, the base oil component B has a chemical structure of a polyalkylene glycol having a hydroxyl group at one or both ends. Examples of the polyalkylene glycol include polypropylene glycol, copolymers (random or block) of polyethylene glycol and polypropylene glycol, and butanol-initiated polypropylene glycol. From the viewpoint of insulation, propylene glycol is more desirable than ethylene glycol.

[0032] The content of base oil component B is suitably 90% by mass or less, and preferably 80% by mass or less, of the total amount of base oil.

[0033] In addition, various additives can be added to the base oil according to the purpose, as in the past. For example, demulsifiers, rust inhibitors, antifoaming agents, antioxidants, acid scavengers, antiwear agents, extreme pressure agents, oiliness agents, detergent dispersants, pour point depressants, viscosity index improvers, metal deactivators, etc. can be added singly or in combination.

[0034] There are no limitations on the type of hydrocarbon refrigerant (that is, a refrigerant with one or more carbon atoms consisting only of carbon and hydrogen), but methane, ethane, ethylene, propane, propylene, n-butane, 2-methylpropane, etc. are preferred. EXAMPLES

[0035] The present invention will now be further described with reference to examples.

[0036] (Base oil component) The base oil components shown in Table 1 were prepared. That is, in the general formula (I), R 1 is a glyceryl group, n is 5.1 for the base oil component (PAG-A in the table), R 1 A base oil component (PAG-B in the table) with n = 2 and a glyceryl group was prepared. The average molecular weight of PAG-A was approximately 1000, and the average molecular weight of PAG-B was approximately 400. PAG-A and PAG-B correspond to base oil component A.

[0037] In addition, in the general formula (II), R 3A base oil component (PAG-M in the table) was prepared in which n is a hydroxyl group (OH group) and n is 16.6. The average molecular weight of PAG-M is approximately 1000, and it corresponds to base oil component B.

[0038] The physical properties of each base oil component were investigated according to JIS. They are shown in Table 1. Note that in the examples described later, the physical property values ​​are also values ​​according to JIS.

[0039] [Table 1]

[0040] (Preparation of base oil) The base oil components were mixed in the ratios shown in Table 2 to prepare the prototype base oils 1 to 6 (all examples) shown in Table 2. For comparison, only PAG-M was used as a comparative base oil. The physical properties of each prototype base oil are also shown in Table 2. In Table 2, "-" indicates that the corresponding component was not contained.

[0041] [Table 2]

[0042] Regarding physical properties, refrigeration oils used in compressors with built-in electric motors combined with highly electrically insulating hydrocarbon refrigerants such as propane have a volume resistivity of 1×10 8 Electrical insulation of at least Ω·cm is required. For example, the volume resistivity of the hydrocarbon refrigerant R-290 is 1×10 13 Ω·cm, and the volume resistivity of the refrigeration oil to be combined with this is 1×10 8 A resistance of Ω·cm or more is required. All of the prototype base oils meet this requirement.

[0043] (Compatibility with hydrocarbon refrigerants) The compatibility of the prototype base oils 1 to 6 and the comparative base oil with the hydrocarbon refrigerant R-290 was evaluated. The results are shown in Table 3, where the unit of refrigerant concentration in the oil is "mass%." In Table 3, "-" indicates that the corresponding component is not contained.

[0044] [Table 3]

[0045] As shown in Table 3, by using the prototype base oil, the amount of refrigerant dissolved was less at each temperature than when the comparative base oil was used.

[0046] From the above, it was verified that by using a base oil containing the base oil component A according to the present invention, the amount of dissolved hydrocarbon refrigerant can be reduced compared to the conventional case.

[0047] (Solubility of additives) It was verified that the performance of the refrigerating machine oil composition would not change even if various additives that have been widely added to refrigerating machine oil compositions were added to the prototype base oil. That is, the phenol-based antioxidant, epoxy-based acid scavenger, imide-based acid scavenger, phosphate-based extreme pressure agent, and siloxane-based antifoaming agent in the table were added to the above prototype base oil to prepare prototype oils, and the dissolution state of each additive in each prototype oil was visually observed, and the physical properties of each prototype oil were investigated. The results are shown in Table 4, where "○" in the additive column indicates that the additive is dissolved in the prototype base oil.

[0048] [Table 4]

[0049] As shown in Table 4, even if the base oil component A is contained, it does not affect the addition of various additives, and it can be used in the same way as before.

[0050] (thermal stability) The thermal stability of the prototype oil was verified under the following test conditions. The results are shown in Table 5, with "○" in the catalyst change column indicating no change. <Test conditions> Test method: Sealed tube test (JIS and ASHRAE compliant) Amount of oil: prototype oil / R-290=1[mL] / 1[mL] Catalyst: Fe, Cu and Al Moisture: 100 [ppm] or less Vacuum degree: 0.1 [mmHg] Temperature: 175[℃] Period: 14 [days]

[0051] [Table 5]

[0052] As shown in Table 5, even if base oil component A is contained, the thermal stability is not decreased and it can be used in the same way as conventional ones.

[0053] (hydrolytic stability) The hydrolytic stability of the sample oils was verified under the following test conditions. The results are shown in Table 6. In the column for catalyst change, "○" indicates no change. <Test conditions> Test method: Sealed tube test (JIS and ASHRAE compliant) Amount of oil: prototype oil / R-290=8[g] / 0.6[g] Catalyst: Fe, Cu and Al Moisture content: 500[ppm] Vacuum degree: 0.1 [mmHg] Temperature: 175[℃] Period: 14 [days]

[0054] [Table 6]

[0055] As shown in Table 6, even if base oil component A is contained, the hydrolysis stability is not decreased and it can be used in the same way as conventional products.

[0056] 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 the composition can be used in the same manner as before. In addition, the amount of hydrocarbon refrigerant used can be reduced, thereby further improving safety.

[0057] [Working fluid for refrigerators] The present invention relates to a working fluid for a refrigerating machine comprising the above refrigerating machine oil composition and a hydrocarbon refrigerant. Suitable hydrocarbon refrigerants include methane, ethane, ethylene, propane, propylene, n-butane, and 2-methylpropane.

[0058] Furthermore, according to the present invention, the amount of hydrocarbon refrigerant used can be reduced, and the safety of the refrigerant as a working fluid for a refrigeration machine can be improved.

Claims

1. A refrigerating machine oil composition for use with a hydrocarbon refrigerant, comprising as a base oil at least one base oil component A represented by the following general formula (I): 【Chemistry 1】 (In the formula, R １ is a glyceryl group, a trimethylolpropyl group, a ditrimethylolpropyl group, a pentaerythritol group, or a dipentaerythritol group; R ２ is a hydrogen atom or a methyl group, m is 3 to 6, and n is 2 to 11.

2. 2. The refrigerator oil composition according to claim 1, wherein the base oil component A is contained in an amount of 10 mass % or more based on the total amount of the base oil.

3. 2. The refrigerator oil composition according to claim 1, wherein the base oil component A has an average molecular weight of 300 to 2,000.

4. The refrigerating machine oil composition according to claim 1, characterized in that the base oil comprises the base oil component A and at least one base oil component B represented by the following general formula (II): 【Chemistry 2】 (In the formula, R is a hydrogen atom or a methyl group, and R ３ is a hydroxyl group (HO-), CH ３ O-, C ２ H ５ O-, C ３ H ７ O- or C ４ H ９ O-, and n is 6 to 33.

5. The refrigerating machine oil composition according to any one of claims 1 to 4, A working fluid for a refrigeration machine comprising:

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