TW201700721A - Refrigeration machine oil and working fluid composition - Google Patents

Abstract

To provide an ester lubricating oil for refrigeration oils, the ester lubricating oil having excellent lubricating properties and heat resistance. An ester for refrigeration oils is obtained from neopentylglycol (component (A)), a linear dihydric alcohol having 2 to 6 carbon atoms with a hydroxyl group at its terminal carbons (component (B)), a linear dicarboxylic acid having 4 to 10 carbon atoms with a carboxyl group at its terminal carbons (component (C)), and a monohydric alcohol having 6 to 12 carbon atoms (component (D)). Relative to 1.0 mol of a constituent derived from the component (A), the ratio of a constituent derived from the component (B) is 0.1 to 0.4 mol, the ratio of a constituent derived from the component (C) is 0.8 to 2.8 mol, and the ratio of a constituent derived from the component (D) is 0.3 to 2.3 mol. The ester has a hydroxyl value of 5 to 40 mgKOH/g and satisfies formula (1) and formula (2). (1) 0.08 ≤ BOH/(AOH+BOH) ≤ 0.15 (2) [BOH/(AOH+BOH)]/[Bmol/(Amol+Bmol)] ≤ 0.9 AOH is the mol number of a terminal hydroxyl group derived from the component (A) in the ester. BOH is the mol number of a terminal hydroxyl group derived from the component (B) in the ester. Amol is the mol number of the constituent derived from the component (A) in the ester. Bmol is the mol number of the constituent derived from the component (B) in the ester.

Description

Working fluid composition for ester oil and refrigerator oil for refrigerator oil

The present invention relates to an ester for a refrigerator oil having excellent lubricity and heat resistance. Further, the invention relates to an ester for a refrigerating machine oil, wherein the ester for a refrigerating machine oil is used in a working fluid composition for a refrigerating machine oil containing a non-chloro Freon refrigerant or a natural refrigerant.

In order to replace the chlorine-containing Freon refrigeration caused by ozone layer damage, etc., in low-temperature equipment such as indoor air conditioners, combined air conditioners, and household refrigerators, industrial refrigerators, and hybrid vehicles and electric vehicles. 1,1,1,2-tetrafluoroethane (R-134a), pentafluoroethane (R-125), as a mixed refrigerant of difluoromethane (R-32) and R-125 A hydrofluorocarbon (HFC) such as -410A is used as a refrigerant.

However, although the ozone layer destruction coefficient of the above HFC refrigerant is zero, the global warming potential (GWP) is as high as 1,000 or more. Therefore, since it is a target for the purpose of reducing the greenhouse effect, its use is controlled, and it is considered to use a refrigerant having a low GWP. For example, conversion to 2,3,3,3-tetrafluoropropene (HFO-1234yf) having a GWP of 4, R-32 having a GWP of 675, or the like is being performed.

With the progress of conversion to a low GWP HFC refrigerant, various refrigerants for refrigerator oils having a polyol ester having high compatibility with these low GWP refrigerants as a base oil have been proposed. Further, in these candidate refrigerant substitutes, when a pressure-increased refrigerant such as R-32 or a mixed refrigerant containing R-32 is used, the discharge temperature of the compressor is increased, and the lubrication condition in the compressor is further increased. Since it is harsh, it is proposed to use an ester for refrigerator oil which improves lubricity and stability.

For example, in Patent Document 1, with the use of a mixed refrigerant containing R-32, as an ester having high stability in a compressor operating in a hot and harsh environment, a pentaerythritol and 2-ethylhexate are disclosed. A lubricating oil for a refrigerating machine oil containing an acid and an ester composed of 3,5,5-trimethylhexanoic acid as a main component.

Further, in the case of a hydrocarbon (HC) refrigerant, since there is no fluorine which improves lubricity in the HC molecule, the effect of improving the lubricity by the refrigerant such as the HFC refrigerant cannot be expected, and the HC refrigerant pair is The refrigerating machine oil has a high solubility and the viscosity of the oil is lowered, so the lubrication conditions become more severe. Patent Document 2 proposes a composite ester which has excellent lubricity and excellent heat resistance under such severe lubrication conditions, and discloses that lubricity is improved by using 1,4-butanediol in a raw material. Monohydric alcohol is used in the raw material to improve heat resistance.

Conventional technical literature

Patent literature

Patent Document 1: Japanese Patent Publication No. 10-8084

Patent Document 2: WO2014/017596

Technical problem to be solved by the present invention

However, the use of refrigerating machine oil has become more severe due to the miniaturization of the equipment using refrigerating machine oil (the reduction in the amount of refrigerating machine oil used per unit) or the increase in energy saving (the operation time of the compressor has been extended due to inverter control). . Therefore, due to the frictional heat of the sliding portion of the compressor, the refrigerant oil exposed to the local high temperature condition is thermally decomposed, and the generated decomposition product corrodes the metal member and adversely affects the resin material, so that development of a kind of product is desired. An ester for refrigerator oil that exhibits excellent lubricity and thermal stability under more severe conditions.

The technical problem of the present invention is to provide an ester lubricating oil for refrigerator oil which has excellent lubricity and heat resistance.

Technical means to solve technical problems

In order to solve the above-mentioned problems, the inventors of the present invention have found that an ester having a specific diol, a dicarboxylic acid, or a monohydric alcohol as a constituent component has excellent lubricity and heat resistance, and has completed the present invention.

That is, the present invention is as follows:

An ester for refrigerator oil, wherein:

The ester for a refrigerator oil is obtained from the following components (A), (B), (C), and (D).

The ratio is 1.0 mol per gram of the constituent component from the component (A) in the ester, and the constituent component derived from the component (B) is 0.1 to 0.4 mol, and the component (C) is derived from the component (C). The constituent component is 0.8 to 2.8 mTorr, and the constituent component derived from the component (D) is 0.3 to 2.3 mTorr.

The ester has a hydroxyl value of 5 to 40 mg KOH/g, which satisfies the formulas (1) and (2).

Neopentyl glycol,

a linear diol having 2 to 6 carbon atoms and having a hydroxyl group on the carbon at both ends,

a linear dicarboxylic acid having a carboxyl group of 4 to 10 and having a carboxyl group at both ends of the carbon,

a monohydric alcohol having 6 to 12 carbon atoms,

0.08£B _OH /(A _OH +B _OH ) £0.15 ......(1)

[B _OH /(A _OH +B _OH )]/[B _mol /(A _mol +B _mol )]£0.9 ......(2)

In the formula (1) and the formula (2),

A _OH is the Moir number of the terminal hydroxyl group derived from the component (A) in the ester;

B _OH is the Moir number of the terminal hydroxyl group derived from the component (B) in the ester;

A _mol is the Moir number of the constituent component derived from the component (A) in the ester;

B _mol is the Moiré number of the constituent component from the component (B) in the ester.

(2) A working fluid composition for a refrigerating machine oil, wherein the refrigerating machine oil working fluid composition contains a non-chlorine-based Freon refrigerant or a natural refrigerant, and the refrigerating machine oil ester according to (1).

Further, in order to obtain the ester for a refrigerator oil, it is preferred to supply the component (A), the component (B), the component (C) and the component (D) to a primary esterification reaction at a temperature of 100 to 150 ° C, and then The secondary esterification reaction is carried out at a temperature of from 150 ° C to 250 ° C.

Effect of the invention

Since the ester for refrigerator oil of the present invention has high heat resistance, it can be suitably used in a compressor of a refrigerating and air-conditioning apparatus which particularly requires thermal stability. Further, since the ester for a refrigerating machine oil of the present invention has high compatibility with a non-chlorine-based Freon refrigerant or a natural refrigerant, it is suitably used in a working fluid composition for a refrigerating machine containing these refrigerants.

Hereinafter, the ester for a refrigerator oil of the present invention will be described.

In addition, the resin range specified by the symbol "~" in this specification includes the value of both ends (upper limit and lower limit) of "~". For example, "2~5" means "2 or more, 5 or less".

The ester for a refrigerator oil of the present invention is obtained by using neopentyl glycol (ingredient (A)) and a linear diol having a hydroxyl group on carbon at both ends of 2 to 6 carbon atoms (ingredient (B) )), a linear dicarboxylic acid having a carboxyl group (component (C)) and a monohydric alcohol having a carbon number of 6 to 12 (component (D)) mixed at both ends of the carbon having 4 to 10 carbon atoms, and It is subjected to an esterification reaction.

In addition, the terms of the component (A), the component (B), the component (C), and the component (D) are a general term for convenience, and the compound of each component may be one type or the compound of each component may be two or more types. When two or more types of compounds are contained in each component, the amount of each component is the total amount of two or more compounds belonging to the component.

As the neopentyl glycol of the component (A) used in the present invention, commercially available neopentyl glycol can be used, and as the form of neopentyl glycol, a solid neopentyl glycol or a water-diluted liquid can be used. Neopentyl glycol.

The component (B) is a linear diol having a hydroxyl group at the carbon at both terminals of 2 to 6 carbon atoms, and specific examples thereof include ethylene glycol, 1,3-propanediol, and 1,4-butane. Alcohol, 1,5-pentanediol, 1,6-hexanediol, and the like. A linear dibasic saturated alcohol is preferred, and 1,4-butanediol is more preferred. By the component (B), an ester excellent in viscosity index, low-temperature stability, and lubricity can be obtained.

The component (C) is a linear dicarboxylic acid having a carboxyl group at the carbon at both terminals of 4 to 10 carbon atoms, and specific examples thereof include succinic acid (having 4 carbon atoms) and glutaric acid (carbon atom). Number 5), adipic acid (carbon number 6), pimelic acid (carbon number 7), suberic acid (carbon number 8), sebacic acid (carbon number 9), sebacic acid (carbon atom) Number 10) and so on. It is preferred to use a linear binary carboxylic acid having 6 to 8 carbon atoms. By the component (C), an ester excellent in viscosity index and low-temperature stability can be obtained.

The component (D) is a monohydric alcohol having 6 to 12 carbon atoms, and these may be any of a linear alcohol and a branched alcohol. Specific examples thereof include 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-nonanol, 1-undecyl alcohol, 1-dodecanol, 2-ethyl Hexanol, 3,5,5-trimethylhexanol, and the like. A saturated branched alcohol having 6 to 10 carbon atoms is preferred, and an ester having excellent low-temperature stability can be obtained. More preferably, 2-ethylhexanol or 3,5,5-trimethylhexanol is used.

The ester for a refrigerating machine oil of the present invention is an ester for a refrigerating machine oil having a ratio of 1.0 mol to a component derived from the component (A) and 0.1 to 0.4 mol of a component derived from the component (B). The component of C) is 0.8 to 2.8 mTorr, and the component derived from component (D) is 0.3 to 2.3 mol.

When the amount of the constituent component derived from the component (B) is less than 0.1 mol with respect to the constituent component of the component (A) of 1.0 mol, it is difficult to obtain a desired viscosity index and lubricity, and if it exceeds 0.4 mol, The low temperature stability of the ester deteriorates. The amount of the constituent component derived from the component (B) is preferably 0.1 to 0.3 mol, based on 1.0 mol of the constituent component derived from the component (A).

When the amount of the component derived from the component (C) is less than 0.8 mol with respect to the constituent component of the component (A) of 1.0 mol, it is difficult to obtain a high viscosity index, and if it exceeds 2.8, it is difficult to obtain lubricity. The amount of the component derived from the component (C) is preferably 0.9 mol or more, and preferably 2.3 mol or less, based on 1.0 mol of the component derived from the component (A).

When the amount of the component derived from the component (D) is from 0.3 to 2.3 mol, the amount of the component derived from the component (D) is from 0.3 to 2.3 mol, and it is easy to obtain an ester having a suitable viscosity for the refrigerating machine oil. The amount of the component derived from the component (D) is preferably 0.5 mol or more, and preferably 2.1 mol or less, based on 1.0 mol of the component derived from the component (A).

The Mohr ratio of each of the above constituent components was analyzed and calculated by gas chromatography. 0.1 g of the ester was diluted with a mixed solvent of 5 g of toluene/methanol (80 wt% / 20 wt%), and then 0.3 g of a 28% sodium methoxide methanol solution (Wako Pure Chemical Industries, Ltd.) was added and allowed to stand at 60 ° C for 30 minutes. The ester is subjected to methanolysis. By analyzing the obtained ester decomposition solution by gas chromatography, the peak area ratio of the obtained component (A), component (B), component (C), and component (D) can be converted into a molar ratio. Calculation. Further, the components of the ester decomposition product can be identified by analyzing the gas chromatography of each component separately.

The ester of the present invention is obtained by adjusting the molar ratio of the constituent components from the respective components (A), (B), (C), and (D) by the component (A), (B) or (D). An ester synthesized by blocking a carboxyl group of the component (C), except that the terminal structure is an ester of an alkyl group derived from the component (D), and the terminal structure of the ester as an accessory component is a hydroxyl group derived from the component (A), and a component ( B) an ester of a hydroxyl group.

An example of a specific terminal structure of the ester of the present invention will be described using the formulas (3), (4), and (5). The formula (3) is a structure having an alkyl group derived from the component (D) at the terminal of the ester, and the formula (4) is a structure having a hydroxyl group derived from the component (A) at the terminal of the ester, and the formula (5) is at the terminal of the ester. A structure having a hydroxyl group derived from the component (B).

Hereinafter, the ester for a refrigerator oil of the present invention will be described.

In addition, the resin range specified by the symbol "~" in this specification includes the value of both ends (upper limit and lower limit) of "~". For example, "2~5" means "2 or more, 5 or less".

The ester for a refrigerator oil of the present invention is obtained by using neopentyl glycol (ingredient (A)) and a linear diol having a hydroxyl group on carbon at both ends of 2 to 6 carbon atoms (ingredient (B) )), a linear dicarboxylic acid having a carboxyl group (component (C)) and a monohydric alcohol having a carbon number of 6 to 12 (component (D)) mixed at both ends of the carbon having 4 to 10 carbon atoms, and It is subjected to an esterification reaction.

In addition, the terms of the component (A), the component (B), the component (C), and the component (D) are a general term for convenience, and the compound of each component may be one type or the compound of each component may be two or more types. When two or more types of compounds are contained in each component, the amount of each component is the total amount of two or more compounds belonging to the component.

As the neopentyl glycol of the component (A) used in the present invention, commercially available neopentyl glycol can be used, and as the form of neopentyl glycol, a solid neopentyl glycol or a water-diluted liquid can be used. Neopentyl glycol.

The component (B) is a linear diol having a hydroxyl group at the carbon at both terminals of 2 to 6 carbon atoms, and specific examples thereof include ethylene glycol, 1,3-propanediol, and 1,4-butane. Alcohol, 1,5-pentanediol, 1,6-hexanediol, and the like. A linear saturated alcohol is preferred, and 1,4-butanediol is particularly preferably used. By the component (B), an ester excellent in viscosity index, low-temperature stability, and lubricity can be obtained.

The component (C) is a linear dicarboxylic acid having a carboxyl group at the carbon at both terminals of 4 to 10 carbon atoms, and specific examples thereof include succinic acid (having 4 carbon atoms) and glutaric acid (carbon atom). Number 5), adipic acid (carbon number 6), pimelic acid (carbon number 7), suberic acid (carbon number 8), sebacic acid (carbon number 9), sebacic acid (carbon atom) Number 10) and so on. It is preferred to use a linear binary carboxylic acid having 6 to 8 carbon atoms. By the component (C), an ester excellent in viscosity index and low-temperature stability can be obtained.

The component (D) is a monohydric alcohol having 6 to 12 carbon atoms, and these may be any of a linear alcohol and a branched alcohol. Specific examples thereof include 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-nonanol, 1-undecyl alcohol, 1-dodecanol, 2-ethyl Hexanol, 3,5,5-trimethylhexanol, and the like. A saturated branched alcohol having 6 to 10 carbon atoms is preferred, and an ester having excellent low-temperature stability can be obtained. More preferably, 2-ethylhexanol or 3,5,5-trimethylhexanol is used.

The ester for a refrigerating machine oil of the present invention is an ester for a refrigerating machine oil having a ratio of 1.0 mol to a component derived from the component (A) and 0.1 to 0.4 mol of a component derived from the component (B). The component of C) is 0.8 to 2.8 mTorr, and the component derived from component (D) is 0.3 to 2.3 mol.

When the amount of the constituent component derived from the component (B) is less than 0.1 mol with respect to the constituent component of the component (A) of 1.0 mol, it is difficult to obtain a desired viscosity index and lubricity, and if it exceeds 0.4 mol, The low temperature stability of the ester deteriorates. The amount of the constituent component derived from the component (B) is preferably 0.1 to 0.3 mol, based on 1.0 mol of the constituent component derived from the component (A).

When the amount of the component derived from the component (C) is less than 0.8 mol with respect to the constituent component of the component (A) of 1.0 mol, it is difficult to obtain a high viscosity index, and if it exceeds 2.8, it is difficult to obtain lubricity. The amount of the component derived from the component (C) is preferably 0.9 mol or more, and preferably 2.3 mol or less, based on 1.0 mol of the component derived from the component (A).

When the amount of the component derived from the component (D) is from 0.3 to 2.3 mol, the amount of the component derived from the component (D) is from 0.3 to 2.3 mol, and it is easy to obtain an ester having a suitable viscosity for the refrigerating machine oil. The amount of the component derived from the component (D) is preferably 0.5 mol or more, and preferably 2.1 mol or less, based on 1.0 mol of the component derived from the component (A).

The Mohr ratio of each of the above constituent components was analyzed and calculated by gas chromatography. 0.1 g of the ester was diluted with a mixed solvent of 5 g of toluene/methanol (80 wt% / 20 wt%), and then 0.3 g of a 28% sodium methoxide methanol solution (Wako Pure Chemical Industries, Ltd.) was added and allowed to stand at 60 ° C for 30 minutes. , the ester is subjected to methanolysis. By analyzing the obtained ester decomposition solution by gas chromatography, the peak area ratio of the obtained component (A), component (B), component (C), and component (D) can be converted into a molar ratio. Calculation. Further, the components of the ester decomposition product can be identified by analyzing the gas chromatography of each component separately.

The ester of the present invention is obtained by adjusting the molar ratio of the constituent components from the respective components (A), (B), (C), and (D) by the component (A), (B) or (D). An ester synthesized by blocking a carboxyl group of the component (C), except that the terminal structure is an ester of an alkyl group derived from the component (D), and the terminal structure of the ester as an accessory component is a hydroxyl group derived from the component (A), and a component ( B) an ester of a hydroxyl group.

An example of a specific terminal structure of the ester of the present invention will be described using the formulas (3), (4), and (5). The formula (3) is a structure having an alkyl group derived from the component (D) at the terminal of the ester, and the formula (4) is a structure having a hydroxyl group derived from the component (A) at the terminal of the ester, and the formula (5) is at the terminal of the ester. A structure having a hydroxyl group derived from the component (B). [Chemical Formula 1] [Chemical Formula 2] [Chemical Formula 3]

m is an integer of 1 to 5, and R ¹ represents an alkyl group derived from the component (D).

According to the above structural design, when used as a refrigerating machine oil, hydrolysis or thermal decomposition is less likely to occur, and an ester having excellent stability can be obtained.

The ester for a refrigerator oil of the present invention satisfies the formulas (1) and (2).

0.08£B _OH /(A _OH +B _OH ) £0.15 ・・・(1)

A _OH is the molar number of the terminal hydroxyl group derived from the component (A) in the ester;

B _OH is the Moir number of the terminal hydroxyl group derived from the component (B) in the ester.

Formula (1) represents the molar ratio of the terminal hydroxyl group derived from the component (B) with respect to the total amount of the terminal hydroxyl group derived from the component (A) and the terminal hydroxyl group derived from the component (B) in the ester.

[B _OH /(A _OH +B _OH )]/[B _mol /(A _mol +B _mol )]£0.9 ......(2)

A _OH is the molar number of the terminal hydroxyl group derived from the component (A) in the ester;

B _OH is the molar number of the terminal hydroxyl group derived from the component (B) in the ester;

A _mol is the Moir number of the constituent component derived from the component (A) in the ester;

B _mol is the Moir number of the constituent component derived from the component (B) in the ester.

The molecule of the formula (2) is [B _OH /(A _OH +B _OH )], which is represented by the formula (1), and represents a terminal hydroxyl group derived from the component (A) and a terminal hydroxyl group derived from the component (B) in the ester. The molar ratio of the terminal hydroxyl groups from the component (B) to the total amount.

On the other hand, the denominator of the formula (2) is [B _mol /(A _mol + B _mol )], which represents the total amount of the constituent component from the component (A) and the constituent component derived from the component (B) in the ester. The Mohr ratio of the constituents derived from the component (B).

Therefore, the formula (2) shows the Mohr ratio of the constituent component derived from the component (B) in the ester, and the molar ratio of the terminal hydroxyl group derived from the component (B) is small, in other words, relative to the ester as a whole. The degree of uneven distribution of the component (B) in the terminal structure of the structure.

Further, each numerical value of the formula (1) (2) was measured in the following manner.

The value of the formula (1) and the value of the molecule of the formula (2): B _OH /(A _OH + B _OH ).

The integrated value of the peak of α hydrogen (3.2 to 3.4 ppm) with respect to the hydroxyl group derived from the component (A) in the ¹ H-NMR spectrum and the peak of α hydrogen derived from the hydroxyl group of the component (B) (3.6 to 3.8) The integral value of ppm) is calculated by dividing the integral value of α hydrogen with respect to the hydroxyl group from the component (B) by the sum of the respective integral values.

The value of the denominator of formula (2): B _mol / (A _mol + B _mol )

The Moiré number of each component from the component (A) and the component (B) was determined by gas chromatography as described above, and the Mohr ratio was calculated.

Component (A) does not bind hydrogen on the β carbon (β hydrogen is not present), so the terminal structure derived from the component (A) is heat resistant to the terminal hydroxyl group generated at the end of the ester structure compared to the terminal structure derived from the component (B). Excellent sex. That is, the ester which is present in a large amount from the ester structure terminal of the component (A) is excellent in heat resistance as compared with the ester which is not such an ester. As a result, the molar ratio of the hydroxyl group derived from the component (B) to the total hydroxyl group is 0.15 or less, whereby an ester having more excellent heat resistance can be formed. When the molar ratio of the terminal hydroxyl group derived from the component (B) is from 0.08 to 0.15 with respect to the total amount of the terminal hydroxyl group derived from the component (A) and the terminal hydroxyl group derived from the component (B), it is easier to obtain excellent lubricity and heat resistance. Ester. From this viewpoint, the Moir ratio is more preferably 0.09 or more, and more preferably 0.14 or less.

Further, the molar ratio of the terminal hydroxyl group derived from the component (B) to the component of the component (B) in which the molar ratio of the component (B) is unevenly distributed is more excellent. The degree of uneven distribution of the component (B) in the terminal structure can be expressed by the molar ratio of the terminal hydroxyl group derived from the component (B) with respect to the molar ratio of the constituent component derived from the component (B) in the ester. When the value is 0.9 or less, an ester having more excellent heat resistance can be obtained. The value may be 0.9 or less, more preferably 0.8 or less. Further, the lower limit of the value is not particularly limited, but is preferably 0.2 or more, more preferably 0.3 or more, and most preferably 0.5 or more.

The ester of the present invention is derived from the component in the ester with respect to the molar ratio of the component derived from the component (B) and the component derived from the component (A) and the component derived from the component (B) in the ester ( The ester of the formula (1) and the formula (2) is an ester which is more excellent in heat resistance, and the ester of the formula (1) and the formula (2) is an ester having a reduced hydroxyl group ratio of all the hydroxyl groups.

In the preparation of the ester, the above component (A), component (B), component (C) and component (D) are all placed in a suitable reactor, and the esterification reaction is carried out under normal pressure and a nitrogen atmosphere. In order to more effectively remove the water formed by the reaction, the esterification reaction can usually be carried out at 150 to 250 °C. However, from the viewpoint of obtaining an ester having more excellent heat resistance, the esterification reaction is first carried out once at 100 to 150 °C. The secondary esterification reaction is then carried out at 150 ° C to 250 ° C.

The primary esterification reaction is preferably carried out at 100 to 140 ° C, more preferably at 100 to 130 ° C, whereby an ester excellent in heat resistance is easily obtained. Further, the primary esterification reaction is preferably from 1 to 10 hours, more preferably from 2 to 8 hours, whereby an ester excellent in heat resistance is easily obtained.

The secondary esterification reaction is preferably carried out at 160 to 260 ° C, more preferably at 180 to 250 ° C. At this time, the secondary esterification reaction is carried out until the acid value is 10 m KOH / g or less, preferably 5 mg KOH / g or less, and further preferably 2 mg KOH / g.

Further, the esterification reaction may be carried out using a Bronsted acid catalyst or a Lewis acid catalyst, but is preferably carried out without a catalyst.

After the esterification reaction, the excess component (D) was distilled off under reduced pressure to obtain a crude ester. Further, the crude ester is purified by an adsorbent, whereby an ester for a target refrigerator oil can be obtained.

The viscosity of the refrigerator oil of the present invention at 40 ° C is preferably 20 to 500 mm ² /s. Further preferably, it is 20 to 300 mm ² /s, more preferably 20 to 250 mm ² /s, and most preferably 20 to 180 mm ² /s. Further, the hydroxyl value is preferably from 5 to 40 mg KOH/g, more preferably from 15 to 35 mg KOH/g.

The ester for refrigerator oil of the present invention may be used alone as a base oil or may be used in combination with other base oils. Further, a conventional additive such as a phenolic antioxidant, a metal passivating agent such as benzotriazole, thiadiazole or dithiocarbamate, an acid such as an epoxy compound or a carbodiimide may be appropriately added depending on the purpose. Additives such as a capture agent and an extreme pressure agent for phosphorus.

Since the ester for a refrigerator oil of the present invention has high compatibility with a non-chlorine-based Freon refrigerant or a natural refrigerant, it can be suitably used in a working fluid composition for a refrigerator containing these refrigerants. Examples of the non-chlorine-based Freon refrigerant include a monomer of a hydrofluorocarbon (HFC), a hydrofluoroolefin (HFO), a hydrocarbon (HC), or a natural refrigerant, or a mixture thereof.

Specific examples of the hydrofluorocarbon (HFC) refrigerant are 1,1,1,2-tetrafluoroethane (R-134a), pentafluoroethane (R-125), and difluoroethane (R). -32), trifluoromethane (R-23), 1,1,2,2-tetrafluoroethane (R-134), 1,1,1-trifluoroethane (R-143a), 1,1 Any one or a mixture of two or more kinds of difluoroethane (R-152a). Examples of the mixed refrigerant include R-407C (R-134a/R-125/R-32=52/25/23% by mass) and R-410R (R-125/R-32=50/50). Mass %), R-404A (R-125/R-143/R-134a=44/52/4% by mass), R-407E (R-134a/R-125/R-32=60/15/25 Mass%), R-410B (R-32/R-125=45/55 mass%), and the like. Among these, it is particularly preferable that the refrigerant containing at least one of R-134a and R-32 is more preferably a single R-32 refrigerant.

As a specific example of the hydrofluoroolefin (HFO) refrigerant, preferred is 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3,3-tetrafluoropropene (HFO-1234ze). ), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-1234ye) and 3,3,3-trifluoropropene (HFO-1243zf) Any one or a mixture of two or more kinds. From the viewpoint of the physical properties of the refrigerant, one or two or more selected from the group consisting of HFO-1225ye, HFO-1234ze, and HFO-1234yf are preferable.

Further, examples of the hydrocarbon (HC) refrigerant include propane (R290), isobutane (R600a), and the like, and a mixture thereof. Examples of the natural refrigerant include ammonia or carbon dioxide. Particularly preferred are R290, R600 and carbon dioxide.

The working fluid composition for refrigerating machine oils, in general, the quality ratio of the refrigerating machine oil ester of the present invention to the non-chlorinated Freon refrigerant or the natural refrigerant is 10:90 to 90:10. When the mass ratio of the refrigerant is in this range, the working fluid composition has an appropriate viscosity, is excellent in lubricity, and has high freezing efficiency, which is preferable.

Example

Hereinafter, the present invention will be further described in detail by way of examples, but the invention should not be construed as limited.

Further, various analyses of the ester oil for refrigerator oil obtained in the examples and the comparative examples were analyzed by the following methods.

Acid value: Measured in accordance with JIS K2501.

Hydroxyl value: Measured in accordance with JIS K0070.

Kinematic viscosity: Measured in accordance with JIS K2283.

Preparation of Example 1

Into a four-necked flask, 124 g (1.19 mol) of neopentyl glycol, 30 g (0.34 mol) of 1,4-butanediol, 355 g (2.43 mol) of adipic acid, and 3,5,5-trimethyl group were added. 339 g (2.35 mol) of hexanol was distilled off at 120 ° C under a nitrogen atmosphere while reacting at normal pressure for 3 hours. Then, the reaction was continued at 200 ° C for 7 hours to an acid value of 2 or less. The excess 3,5,5-trimethylhexanol was then removed by distillation at 200 ° C under a reduced pressure of 1 to 5 kPa to obtain a crude ester. The crude ester was cooled, and an acid white clay and a ceria-alumina adsorbent were added thereto to obtain 1.0% by mass of the theoretically obtained ester amount, respectively, and subjected to adsorption treatment. The adsorption treatment temperature, pressure, and adsorption treatment time were set to 100 ° C, 1 to 5 kPa, and 2 hours. Finally, filtration was carried out using a 1 micron filter paper to obtain the target ester.

Preparation of Example 2

Into a four-necked flask, neopentyl glycol 180 g (1.73 mol), 1,4-butanediol 25 g (0.28 mol), adipic acid 360 g (2.47 mol), 3,5,5-trimethyl group were added. 256 g (1.78 mol) of hexanol was distilled off under a nitrogen atmosphere at 115 ° C while reacting at normal pressure for 4 hours. The subsequent steps were carried out in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 3

To a four-necked flask, pentadyl glycol 205 g (1.97 mol), 1,4-butanediol 26 g (0.28 mol), adipic acid 373 g (2.55 mol), 3,5,5-trimethyl group were added. 217 g (1.50 mol) of hexanol was distilled off under a nitrogen atmosphere at 125 ° C while reacting at normal pressure for 3 hours. The subsequent steps were carried out in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 4

Add neopentyl glycol 174 g (1.66 mol), 1,4-butanediol 46 g (0.51 mol), adipic acid 373 g (2.55 mol), 3,5,5-trimethyl group to a four-necked flask. 238 g (1.65 mol) of hexanol was distilled off under a nitrogen atmosphere at 120 ° C while reacting at normal pressure for 4 hours. The subsequent steps were carried out in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 5

To a four-necked flask, neopentyl glycol 129 g (1.23 mol), 1,5-pentanediol 28 g (0.26 mol), suberic acid 393 g (2.25 mol), n-octanol 300 g (2.30 mol) were added. The reaction water was distilled off under a nitrogen atmosphere at 120 ° C while reacting at normal pressure for 5 hours. The subsequent steps were carried out in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 6

To a four-necked flask was added 215 g (2.07 mol) of neopentyl glycol, 22 g (0.29 mol) of 1,3-propanediol, 385 g (2.64 mol) of adipic acid, and 3,5,5-trimethylhexanol. 214 g (1.49 mol), the reaction water was distilled off under a nitrogen atmosphere at 120 ° C while reacting at normal pressure for 4 hours. The subsequent steps were carried out in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 7

211 g (2.03 mol) of neopentyl glycol, 42 g (0.36 mol) of 1,6-hexanediol, 385 g (2.64 mol) of adipic acid, and 3,5,5-trimethyl group were added to the four-necked flask. 206 g (1.43 mol) of hexanol was distilled off under a nitrogen atmosphere at 115 ° C while reacting at normal pressure for 5 hours. The subsequent steps were carried out in the same manner as in Example 1 to obtain the target ester.

Preparation of Comparative Example 1

Add neopentyl glycol 174 g (1.66 mol), 1,4-butanediol 46 g (0.51 mol), adipic acid 373 g (2.55 mol), 3,5,5-trimethyl group to a four-necked flask. 238 g (1.65 mol) of hexanol was distilled off at 200 ° C under a nitrogen atmosphere, and the reaction was continued at normal pressure for 7 hours until the acid value was 2 or less. Then, excess 3,5,5-trimethylhexanol was distilled off at 200 ° C under a reduced pressure of 1 to 5 kPa to obtain a crude ester. The crude ester was cooled, and an acid white clay and a ceria-alumina adsorbent were added thereto to obtain 1.0% by mass of the theoretically obtained ester amount, respectively, and subjected to adsorption treatment. The adsorption treatment temperature, pressure, and adsorption treatment time were set to 100 ° C, 1 to 5 kPa, and 2 hours. Finally, filtration was carried out using a 1 micron filter paper to obtain the target ester.

Preparation of Comparative Example 2

Into a four-necked flask, 104 g (1.00 mol) of neopentyl glycol, 27 g (0.30 mol) of 1,4-butanediol, and 351 g (2.40 mol) of adipic acid were added, and the mixture was distilled at 200 ° C under a nitrogen atmosphere. The reaction water was removed while reacting at normal pressure for 3 hours to an acid value of 270 or less to obtain an ester intermediate. Further, 361 g (2.50 mol) of 3,5,5-trimethylhexanol was added to the ester intermediate, and the reaction was continued for 7 hours until the acid value was 2 or less. Then, excess 3,5,5-trimethylhexanol was distilled off at 200 ° C under a reduced pressure of 1 to 5 kPa to obtain a crude ester. The crude ester was cooled, and an acid white clay and a ceria-alumina adsorbent were added thereto to obtain 1.0% by mass of the theoretically obtained ester amount, respectively, and subjected to adsorption treatment. The adsorption treatment temperature, pressure, and adsorption treatment time were set to 100 ° C, 1 to 5 kPa, and 2 hours. Finally, filtration was carried out using a 1 micron filter paper to obtain the target ester.

Heat resistance (heating test)

The above-mentioned ester for refrigerating machine oil was evaluated for heat resistance of the ester for refrigerating machine oil by a heating test, and the heat resistance test was carried out by heating in a thermostat at 130 ° C for 72 hours in an air atmosphere, and measuring the refrigerating machine oil after heating. The acid value of the ester.

Lubricity (SRV test)

The above-mentioned ester for refrigerator oil was evaluated for lubricity by an SRV tester. The SRV test was carried out in a ball/disc, and the test pieces were each made using SUJ-2. The test conditions were carried out at a test temperature of 60 ° C, a load of 100 N, an amplitude of 1 mm, and a vibration number of 50 Hz, and the diameter of the wear scar after 25 minutes of the test time was measured.

The preparation conditions of Examples 1 to 7 and Comparative Examples 1 and 2 are summarized in Tables 1 and 2, and physical properties, heat resistance, and lubricity are summarized in Tables 3 and 4. In addition, Tables 1 and 2 describe the ratio of addition of each component, and Table 3 and Table 4 show the measured value of the Moire ratio of the component from each component in the produced ester.

[Table 1]

[Table 2]

[table 3]

[Table 4]

As shown in Tables 1 to 4, the esters of Examples 1 to 7 are excellent in lubricity and excellent in heat resistance. Therefore, they are difficult to deteriorate even under severe lubrication conditions in a compressor, and can be used for a long period of time. Further, since the increase in the acid value in the heating test is suppressed, the generation of decomposition products which are causes of corrosion such as metal in the compressor is also suppressed.

On the other hand, in Comparative Examples 1 and 2, since the increase in the acid value different from the ester of the example was large, the decomposition of the ester due to the heating test was confirmed as compared with the examples.

no

no

no

Claims (2)

An ester for a refrigerator oil obtained from the following component (A), component (B), component (C) and component (D) in a ratio relative to the component derived from the ester ( The component of A) is 1.0 m, the component from the component (B) is 0.1 to 0.4 mol, and the component derived from the component (C) is 0.8 to 2.8 m, and the composition derived from the component (D) The composition is 0.3 to 2.3 moles, (A) neopentyl glycol, (B) a linear diol having 2 to 6 carbon atoms and having a hydroxyl group at both ends of the carbon, (C) having 4 to 10 carbon atoms a linear dicarboxylic acid having a carboxyl group at both ends of the carbon, (D) a monohydric alcohol having 6 to 12 carbon atoms, wherein the ester has a hydroxyl value of 5 to 40 mgKOH/g, which satisfies the formula (1) And (2), 0.08£B _OH /(A _OH +B _OH ) £0.15 (1) [B _OH /(A _OH +B _OH )]/[B _mol /(A _mol +B _mol )]£0.9 ... (2) In the formula (1) and the formula (2), A _{OH is} the Moir number of the terminal hydroxyl group derived from the component (A) in the ester; B _{OH is} the component derived from the ester (B) ) number of terminal hydroxyl Moore; a _mol number for moire constituent from the component (a) of the ester; B _mol for the ester to The number of moire component constituting the component (B) is. A working fluid composition for a refrigerating machine oil, comprising a non-chlorine-based Freon refrigerant or a natural refrigerant, and an ester for a refrigerating machine oil according to claim 1.