阅读说明：本技术 冷冻机油用酯及包含该冷冻机油用酯的工作流体组合物 (Ester for refrigerator oil and working fluid composition containing the same ) 是由 上田成大 小田和裕 川本英贵 于 2020-04-14 设计创作，主要内容包括：本发明提供一种在与非氯类制冷剂一同使用时可达成优异的制冷剂相容性的冷冻机油用酯。所述冷冻机油用酯由成分(A)、成分(B)及成分(C)的酯反应物构成。相对于1.0摩尔来自成分(A)的构成成分,来自成分(B)的构成成分为0.02～0.4摩尔,来自所述成分(C)的构成成分为3.2～3.96摩尔,且满足式(1),(A)季戊四醇(B)碳原子数为4～10的直链状二元羧酸(C)碳原子数为4～10的一元羧酸α≤峰组(a)/峰组(b)≤β···(1)α＝-10×(来自成分(B)的构成成分的摩尔数)+6.5···(2)β＝-10×(来自成分(B)的构成成分的摩尔数)+7.5···(3)峰组(a)为由气相色谱法得到的、保留时间为28～40分钟时观测到的峰面积的总和,峰组(b)为由所述气相色谱法得到的、保留时间为40～60分钟时观测到的峰面积的总和。(Provided is an ester for refrigerating machine oil, which can achieve excellent refrigerant compatibility when used together with a non-chlorine refrigerant. The ester for refrigerating machine oil comprises an ester reactant of a component (A), a component (B), and a component (C). The component (B) is contained in an amount of 0.02-0.4 mol per 1.0 mol of the component (A), and the component (C) is contained in an amount of 3.2-3.96 mol per 1.0 mol of the component (C). The ester for refrigerating machine oil satisfies formula (1): (A) pentaerythritol; (B) a linear dicarboxylic acid having 4-10 carbon atoms; (C) a monocarboxylic acid having 4-10 carbon atoms, wherein alpha is less than or equal to the ratio of the peak group (a) to the peak group (B), and beta is less than or equal to the ratio of the peak group (a) to the peak group (B); (1) alpha is-10×(the number of moles of the component (B)) plus 6.5; (2) beta is-10×(the number of moles of the component (B)) plus 7.5; and (3) the peak group (a) is the sum of the peak areas observed at a retention time of 28-40 minutes, obtained by gas chromatography, and the peak group (B) is the sum of the peak areas observed at a retention time of 40-60 minutes, obtained by gas chromatography.)

1. An ester for a refrigerator oil, which comprises an ester reactant of the following component (A), component (B) and component (C),

the ratio of the component (B) to the component (A) is 0.02 to 0.4mol, the ratio of the component (C) to the component (B) is 3.2 to 3.96 mol, and the formula (1) is satisfied,

(A) pentaerythritol

(B) A linear dicarboxylic acid having 4 to 10 carbon atoms

(C) C4-10 monocarboxylic acid

Alpha is less than or equal to peak group (a)/peak group (b) is less than or equal to beta (1)

α ═ -10 × (the number of moles of constituent components derived from component (B) +6.5 · (2)

β -10 × (the number of moles of constituent components derived from component (B) +7.5 · (3))

In the formula (1), the reaction mixture is,

the peak group (a) is the sum of peak areas obtained by gas chromatography and observed when the retention time is 28 to 40 minutes,

the peak group (b) is the sum of peak areas obtained by the gas chromatography and observed when the retention time is 40 to 60 minutes.

2. A working fluid composition for a refrigerator oil, characterized by comprising an R-32 refrigerant and the ester for a refrigerator oil according to claim 1.

Technical Field

The present invention relates to an ester for a refrigerator oil having excellent refrigerant compatibility. Also disclosed is an ester for a refrigerator oil, which is characterized by being used in a working fluid composition for a refrigerator oil containing an R-32 refrigerant.

Background

In a refrigerating and air-conditioning system represented by an air-conditioning apparatus such as an indoor air conditioner or a combination air conditioner, a low-temperature apparatus such as a refrigerator for home use, a refrigerator for industrial use, and a vehicle-mounted air conditioner such as a hybrid car or an electric car, a change from a refrigerant having a high global warming potential to a refrigerant having a low global warming potential is performed in order to reduce a greenhouse effect in consideration of global environment. For example, in air conditioning machines, R-32 refrigerant is increasingly used.

It is desirable that the refrigerating machine oil, which is a lubricating oil used in a compressor for compressing a refrigerant, is compatible with the refrigerant without separating under a wide temperature condition. However, for example, there is a technical problem that it is difficult to make the R-32 refrigerant compatible with the refrigerator oil. In view of the above-mentioned problems, development of an ester for a refrigerator oil having compatibility with an R-32 refrigerant has been advanced, and patent document 1 discloses that a tetraester composed of pentaerythritol, 2-methylpropanoic acid and 3,5, 5-trimethylhexanoic acid, which uses a short-chain fatty acid, exhibits excellent compatibility with an R-32 refrigerant. Under the condition that the concentration of the refrigerant in the refrigerator oil is several tens% with respect to the refrigerant, the compatibility between the refrigerant and the refrigerator oil is usually the worst. Accordingly, patent document 1 shows that the compatibility is good under the condition that the amount of the refrigerant oil is 10 mass% with respect to the R-32 refrigerant.

In addition, in a refrigerating-air conditioning system using an R-32 refrigerant, the discharge temperature of the compressor is increased due to high pressure, and as a result, the oil film of the refrigerating machine oil becomes thin and the lubricating conditions become severe, so that a refrigerating machine oil having good lubricity is required. In order to solve such a problem, there are methods of using an additive for improving lubricity or using an ester for a refrigerating machine oil having good lubricity.

For example, as an ester for a refrigerator oil having good lubricity, patent document 2 discloses a composite ester obtained by polycondensation of neopentyl glycol or 1, 4-butanediol as a polyol and adipic acid as a polycarboxylic acid. The complex ester having an oligomer structure obtained by polycondensing a polyol and a polycarboxylic acid has a reduced compatibility with a refrigerant by increasing the molecular weight, but exhibits good lubricity even under severe lubricating conditions.

Documents of the prior art

Patent document

Patent document 1: WO2012/026214 publication

Patent document 2: WO2014/017596 publication

Disclosure of Invention

Technical problem to be solved by the invention

However, in the combination of an R-32 refrigerant that is difficult to be compatible with refrigerating machine oil and a complex ester having a complex structure by polycondensation, the compatibility is less likely to be deteriorated in the case where the refrigerating machine oil concentration is low, as compared with the case where the refrigerating machine oil concentration in the refrigerant, which is likely to be deteriorated, is high. Therefore, a composite ester having excellent compatibility even under a condition that the concentration of the refrigerant in the refrigerator oil is low has been desired.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide an ester for a refrigerating machine oil which can achieve excellent refrigerant compatibility even when an R-32 refrigerant is used together, and a working fluid composition for a refrigerating machine using the ester for a refrigerating machine oil.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that an ester comprising a specific tetrahydric alcohol, a specific dicarboxylic acid and a specific monocarboxylic acid and satisfying a specific formula has excellent refrigerant compatibility with an R-32 refrigerant, thereby completing the present invention.

Namely, the present invention is as follows:

(1) an ester for a refrigerating machine oil, characterized in that it comprises an ester reactant of the following component (A), component (B) and component (C),

the ratio of the constituent component derived from the component (B) is 0.02 to 0.4mol and the ratio of the constituent component derived from the component (C) is 3.2 to 3.96 mol with respect to 1.0 mol of the constituent component derived from the component (A), and the formula (1) is satisfied.

(A) Pentaerythritol

(B) A linear dicarboxylic acid having 4 to 10 carbon atoms

(C) C4-10 monocarboxylic acid

Alpha is less than or equal to peak group (a)/peak group (b) is less than or equal to beta (1)

α ═ -10 × (the number of moles of constituent components derived from component (B) +6.5 · (2)

β -10 × (the number of moles of constituent components derived from component (B) +7.5 · (3))

In the formula (1), the reaction mixture is,

the peak group (a) is the sum of peak areas obtained by gas chromatography and observed when the retention time is 28 to 40 minutes,

the peak group (b) is the sum of peak areas obtained by the gas chromatography and observed when the retention time is 40 to 60 minutes.

(2) A working fluid composition for a refrigerator oil, characterized by comprising an R-32 refrigerant and the ester for a refrigerator oil of (1).

Effects of the invention

The ester for refrigerating machine oil of the present invention can maintain good refrigerant compatibility even for R-32 refrigerant having low dissolving power in a wide range of mixed compositions.

Drawings

FIG. 1 is a graph showing the results of gas chromatography-based analysis of esters.

Detailed Description

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

In the present specification, the numerical range defined by the symbols "to" includes both ends (upper limit and lower limit) of the "to" value. For example, "2 to 5" means "2 or more and 5 or less".

The ester for a refrigerator oil of the present invention is obtained by mixing pentaerythritol (component (a)), a linear dicarboxylic acid having 4 to 10 carbon atoms (component (B)), and a monocarboxylic acid having 4 to 10 carbon atoms (component (C)), and subjecting the mixture to an esterification reaction.

The terms of the component (a), the component (B) and the component (C) are used for convenience, and one compound may be used for each component, or two or more compounds may be used for each component. When each component contains two or more compounds, the amount of each component is the total amount of the two or more compounds belonging to the component.

As the pentaerythritol as the component (A) used in the present invention, commercially available pentaerythritol can be used.

The component (B) is a linear dicarboxylic acid having 4 to 10 carbon atoms. If the number of carbon atoms of the component (B) is less than 4, the refrigerant compatibility is poor, and therefore the number of carbon atoms is preferably 4 or more, more preferably 6 or more. When the number of carbon atoms of the component (B) exceeds 10, the refrigerant compatibility is deteriorated, and therefore the number of carbon atoms is set to 10 or less, and more preferably 8 or less. Examples of the component (B) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, and adipic acid is particularly preferable.

The component (C) is a monocarboxylic acid having 4 to 10 carbon atoms, and may be either linear or branched. The number of carbon atoms of the component (C) is more preferably 4 or more, and further preferably 8 or less. Examples of the component (C) include straight chain fatty acids such as butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid and capric acid, and branched fatty acids such as 2-methylpropionic acid, 2-methylbutyric acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylhexanoic acid and 3,5, 5-trimethylhexanoic acid. These compounds may be used alone or in combination of two or more.

As the component (C), it is particularly preferable to use one or more (C1) linear or branched fatty acids having 4 to 5 carbon atoms and one or more (C2) linear or branched fatty acids having 8 to 9 carbon atoms in a mixture in a molar ratio ((C1)/(C2)) of 1/99 to 99/1. In this embodiment, more preferably, the molar ratio (C1/C2): 1/99-99/1, 2-methylpropanoic acid (C1) and 2-ethylhexanoic acid (C2) are used in combination.

The molar ratio ((C1)/(C2)) is more preferably 40/60 to 90/10, and still more preferably 60/40 to 75/25.

The ester for refrigerating machine oil of the present invention is composed of a constituent derived from the component (a), a constituent derived from the component (B), and a constituent derived from the component (C) in the following ratios: the amount of the component (B) is 0.02 to 0.4mol, and the amount of the component (C) is 3.2 to 3.96 mol, based on 1mol of the component (A).

If the amount of the component derived from the component (B) is less than 0.02 mol or exceeds 0.4mol based on 1mol of the component derived from the component (a), sufficient compatibility cannot be maintained in a wide mixing ratio. Therefore, the amount of the constituent component derived from the component (B) is 0.02 mol or more and 0.4mol or less, preferably 0.05 to 0.35 mol, and more preferably 0.1 to 0.3 mol.

The ratio of the component (C) to 1 mole of the component (a) is preferably 3.3 to 3.9 moles, and more preferably 3.4 to 3.8 moles.

The molar ratio of each constituent component was analyzed and calculated by gas chromatography.

That is, 0.1g of the ester was diluted with 5g of a mixed solvent of toluene/methanol (80 wt%/20 wt%), and then 0.3g of 28% sodium methoxide methanol solution (Wako pure chemical industries, Ltd.) was added thereto, and the mixture was allowed to stand at 60 ℃ for 30 minutes to methanolyze the ester. The obtained ester decomposition solution was analyzed by gas chromatography, and the peak area ratios of the obtained component (a), component (B), component (C1), and component (C2) were calculated by conversion into molar ratios. In addition, the components of the ester decomposition product can be identified by gas chromatography analysis of the individual components.

The ester for a refrigerator oil of the present invention satisfies formula (1).

Alpha is less than or equal to peak group (a)/peak group (b) is less than or equal to beta (1)

α ═ -10 × (the number of moles of constituent components derived from component (B) +6.5 · (2)

β -10 × (the number of moles of constituent components derived from component (B) +7.5 · (3))

The peak group (a) and the peak group (b) were calculated by gas chromatography using the following measurement conditions.

Peak group (a): the sum of peak areas observed when the retention time is 28-40 minutes

Peak group (b): the sum of peak areas observed when the retention time is 40-60 minutes

That is, fig. 1 is a graph showing the results of analysis of an ester by gas chromatography. In fig. 1, the peak group (a) is the sum of the areas of the peaks observed when the retention time is 28 to 40 minutes, and the peak group (b) is the sum of the areas of the peaks observed when the retention time is 40 to 60 minutes.

When the value of expression (1) is smaller than α, the compatibility with the refrigerant is poor, and therefore, α or more is preferably α +0.1 or more, and more preferably α +0.2 or more. When the value of formula (1) exceeds β, the compatibility with the refrigerant is not improved even if it is not deteriorated, and sufficient lubricity may not be obtained in some cases, and therefore, β is preferably β or less, more preferably β -0.1 or less, and still more preferably β -0.2 or less.

The conditions for gas chromatography when calculating the value of formula (1) are set as follows.

The measurement conditions were as follows:

the detection device comprises: FID, injection port temperature: 400 ℃, detector temperature: at a temperature of 400 c,

a chromatographic column: "DB-1 HT" (length 15m, inner diameter 0.25mm) manufactured by Agilent Technologies, Inc.)

Temperature of the column oven: after the column temperature was held at 60 ℃ for 5 minutes from the start of measurement, the temperature was raised at a rate of 10 ℃/minute to 300 ℃ and at a rate of 4 ℃/minute to 400 ℃ after reaching 300 ℃, and then the column temperature was held at 400 ℃ for 16 minutes

Carrier gas: helium (line speed: 55 cm/sec)

Sample introduction amount: 1.0 μ L, split ratio: 100

Sample preparation: 0.1g of the ester for refrigerator oil was diluted with 1.4g of toluene

In the production of an ester, first, the component (a), the component (B) and the component (C) are all charged into an appropriate reaction vessel, and an esterification reaction is carried out under normal pressure and in a nitrogen atmosphere. In order to effectively remove the water generated by the reaction, the esterification reaction is usually carried out at 150 to 250 ℃, preferably at 200 to 250 ℃. In addition, Bronsted acid (Bronsted acid) catalysts or Lewis acid (Lewis acid) catalysts may also be used for the esterification reaction.

Further, a solvent may be used in the esterification reaction in order to effectively remove water produced by the reaction out of the reaction system. Examples of the solvent include aromatic hydrocarbon solvents such as toluene and p-xylene, and hydrocarbon solvents such as cyclohexane and methylcyclohexane; ketone solvents such as methyl isobutyl ketone and 3-pentanone. The solvent having a boiling point of 100 to 200 ℃ is preferred. The solvent having a boiling point of 100 ℃ or lower lowers the temperature in the reaction system, and the esterification reaction proceeds slowly. If the boiling point exceeds 200 ℃, it becomes difficult to remove the solvent from the reaction system. Further, from the viewpoint of satisfying the formula (1). Further preferably, the solubility parameter (SP value) is 7.0 to 9.5 (cal/cm)³)^1/2A solvent in the range of (1). Examples thereof include p-xylene, methylcyclohexane, 4-methyl-2-pentanone and the like. The solubility parameter (SP value) of the solvent can be calculated according to the equation of Fedor, and the details thereof are described in "SP value basis-application and calculation method" (published by shanxi institute of information, 2006), and are obtained based on the description.

After the esterification reaction, when unreacted raw materials and a solvent were used, the solvent was distilled off under reduced pressure to obtain a crude ester. Further, the crude ester may be subjected to deoxidation with an alkali, and adsorption treatment or steam treatment using an active white clay, an acid white clay, or a synthetic adsorbent may be carried out alone or in combination to obtain the ester.

The ester for refrigerating machine oil of the present invention can be used alone as a base oil, or can be used in combination with other base oils. Further, known additives, for example, a phenolic antioxidant, a metal deactivator such as benzotriazole, thiadiazole or dithiocarbamate, an acid scavenger such as epoxy compound or carbodiimide, a phosphorus extreme pressure agent, and the like may be blended as appropriate depending on the purpose.

The ester for a refrigerator oil of the present invention has high compatibility with an R-32 (difluoroethane) refrigerant, and therefore can be suitably used for a working fluid composition for a refrigerator containing an R-32 refrigerant having low compatibility with a refrigerator oil.

A mixed refrigerant containing R-32 may be used, and examples thereof include a mixed refrigerant of R-407C (R-134 a/R-125/R-32: 52/25/23 mass%), R-410R (R-125/R-32: 50/50 mass%), R-1123/R-32: 40/60 mass%, and the like.

In the working fluid composition for a refrigerator oil, the mass ratio of the ester for a refrigerator oil of the present invention to the R-32 refrigerant (ester for a refrigerator oil/non-chlorine Freon refrigerant) is 1/99 to 90/10 in a normal case. When the mass ratio of the refrigerant is within this range, the working fluid composition has appropriate viscosity, excellent lubricity, and high refrigeration efficiency, and therefore, is preferable.

Examples

The present invention will be described in further detail with reference to examples below, but the present invention is not limited to the examples below.

(example 1)

To a 1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a Dimroth (Dimroth) condenser and a 30mL oil-water separator tube were added the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): adipic acid 38.0g (0.26 mol); ingredient (C1): 236.1g (2.68mol) of 2-methylpropanoic acid; ingredient (C2): 151.4g (1.05mol) of 2-ethylhexanoic acid; 60g of 4-methyl-2-pentanone as a reaction solvent was finally added 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol having been added.

The reaction solution which had been charged was heated under a nitrogen stream, and the reaction was carried out at a temperature of 230 ℃ until the reaction purified water was distilled out of the reaction system. Then, the reaction vessel was cooled to 200 ℃ and the pressure was reduced to 80Torr, and unreacted raw materials and the reaction solvent were distilled off to the outside of the reaction system to obtain a crude ester.

After cooling the crude ester to 85 ℃, potassium hydroxide in an amount of 1.5 equivalents based on the acid value was diluted with ion-exchanged water to prepare a 10% solution, which was added to the reaction solution and stirred for 1 hour. After the stirring was stopped, the mixture was left standing for 30 minutes and separated into a lower aqueous layer. Subsequently, ion-exchanged water was added in an amount of 20 mass% based on the reaction solution, the mixture was stirred at 85 ℃ for 10 minutes, and after standing for 15 minutes, the operation of removing the separated water layer was repeated until the pH of the water layer became 7 to 8. Then, the mixture was stirred at 100 ℃ and 30Torr for 1 hour to dehydrate the mixture. Finally, 2 mass% of activated white clay was added to the reaction mixture, and the mixture was stirred at 80 ℃ and 30Torr for 1 hour, and then filtered through a 1 μm filter (filter) to remove the adsorbent, thereby obtaining the compound of example 1.

(example 2)

A1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a serpentine condenser and a 30mL oil-water separator was charged with the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): adipic acid 20.5g (0.14 mol); ingredient (C1): 210.6g (2.39mol) of 2-methylpropanoic acid; ingredient (C2): 225.0g (1.56mol) of 2-ethylhexanoic acid; 60g of p-xylene as a reaction solvent, and finally 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol having been added were added. The subsequent steps were carried out in the same manner as in example 1 to obtain the compound of example 2.

(example 3)

A1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a serpentine condenser and a 30mL oil-water separator was charged with the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): adipic acid 17.5g (0.12 mol); ingredient (C1): 195.1g (1.91mol) of n-pentanoic acid; ingredient (C2): 332.2g (2.10mol) of 3,5, 5-trimethylhexanoic acid was added, and finally 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol which had been added was added. The subsequent steps were carried out in the same manner as in example 1 to obtain the compound of example 3.

(example 4)

A1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a serpentine condenser and a 30mL oil-water separator was charged with the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): 58.5g (0.4mol) of adipic acid; ingredient (C1): 227.3g (2.58mol) of 2-methylpropanoic acid; ingredient (C2): 131.2g (0.91mol) of 2-ethylhexanoic acid; 60g of 4-methyl-2-pentanone as a reaction solvent was finally added 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol having been added. The subsequent steps were carried out in the same manner as in example 1 to obtain the compound of example 4.

(example 5)

A1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a serpentine condenser and a 30mL oil-water separator was charged with the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): 58.5g (0.4mol) of adipic acid; component (C): 313.6g (3.56mol) of 2-methylpropanoic acid; 60g of p-xylene as a reaction solvent, and finally 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol having been added were added. The subsequent steps were carried out in the same manner as in example 1 to obtain the compound of example 5.

Comparative example 1

A1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a serpentine condenser and a 30mL oil-water separator was charged with the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): adipic acid 35.1g (0.24 mol); ingredient (C1): 254.6g (2.89mol) of 2-methylpropanoic acid; ingredient (C2): 151.4g (1.05mol) of 2-ethylhexanoic acid, and finally 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol that had been added was added.

The reaction solution was heated to 150 ℃ under a nitrogen stream, and the temperature was maintained for 48 hours. Then, the temperature was raised to 220 ℃ to react for 24 hours. Then, filtration was performed using a 1 μm filter, thereby obtaining the compound of comparative example 1.

Comparative example 2

A1L four-necked flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a serpentine condenser and a 30mL oil-water separator was charged with the following components: component (A): 136.2g (1.00mol) of pentaerythritol; component (B): adipic acid 71.6g (0.49 mol); ingredient (C1): 289.8g (3.29mol) of 2-methylpropanoic acid; ingredient (C2): 24.5g (0.17mol) of 2-ethylhexanoic acid, and finally 0.2mol equivalent of isopropyl titanate with respect to the hydroxyl group of the alcohol which had been added was added. The subsequent steps were carried out in the same manner as in example 1 to obtain a compound of comparative example 2.

(calculation of the value of equation (1))

The values of the peak group (a) and the peak group (b) were calculated under the following conditions.

The measurement conditions are as follows.

Gas chromatograph: "GC-2014" manufactured by Shimadzu Corporation "

The detection device comprises: FID, injection port temperature: 400 ℃, detector temperature: at a temperature of 400 c,

a chromatographic column: "DB-1 HT" (length 15m, inner diameter 0.25mm) manufactured by Agilent Technologies, Inc.)

Temperature of the column oven: after the column temperature was held at 60 ℃ for 5 minutes from the start of measurement, the temperature was raised at a rate of 10 ℃/minute to 300 ℃ and at a rate of 4 ℃/minute to 400 ℃ after reaching 300 ℃, and then the column temperature was held at 400 ℃ for 16 minutes

Carrier gas: helium (line speed: 55 cm/sec)

Sample introduction amount: 1.0 μ L, split ratio: 100

Sample preparation: 0.1g of the ester for a refrigerator oil was diluted with 1.4g of toluene.

(calculation of. alpha. and. beta.)

The molar ratios of the constituent components derived from the component (B) are calculated based on the formulas (2) and (3).

(compatibility test (1))

The samples of examples 1 to 3 and comparative examples 1 and 2 were prepared under the condition that the mass ratio of the refrigerant R-32 to the ester was 80:20 in accordance with JIS K-2211, and the temperature of two-layer separation in the low temperature range was measured. The two-layer separation temperature was evaluated as "very good" at-50 ℃ or lower, the two-layer separation temperature was evaluated as "o" within a range of-50 to-30 ℃, and the two-layer separation temperature was evaluated as "x" at-30 ℃ or higher.

(compatibility test (2))

Each sample was prepared under the condition that the mass ratio of R-32 refrigerant to the ester of each example and comparative example was 95:5 in accordance with JIS K-2211, and the temperature of two-layer separation in the low temperature region was measured. The two-layer separation temperature was evaluated as "very good" at-35 ℃ or lower, the two-layer separation temperature was evaluated as "o" within a range of-35 to-25 ℃, and the two-layer separation temperature was evaluated as "x" at-25 ℃ or higher.

The results of examples 1 to 5 are shown in table 1, and the results of the formula (1) and the compatibility test of comparative examples 1 and 2 are shown in table 2.

[ Table 1]

[ Table 2]

As shown in examples 1 to 5, according to the present invention, an ester for a refrigerator oil which exhibits good refrigerant compatibility with a refrigerant and is applicable to compressors of refrigerating and air-conditioning apparatuses in a wide range can be obtained.

Comparative example 1, in which the value calculated from formula (1) is out of the range, has poor refrigerant compatibility under the condition that the oil concentration is 5% with respect to the refrigerant.

In comparative example 2 in which the value calculated by the formula (1) is out of the range and the constituent ratio of the component (B) is out of the range, the refrigerant compatibility is poor under both conditions of 20% and 5% of the oil concentration with respect to the refrigerant.