WO2016199718A1

WO2016199718A1 - Ester for refrigeration oil and working fluid composition for refrigeration oil

Info

Publication number: WO2016199718A1
Application number: PCT/JP2016/066756
Authority: WO
Inventors: 文隆吉川; 武加治木; 宗宏山田; 成大上田
Original assignee: 日油株式会社
Priority date: 2015-06-08
Filing date: 2016-06-06
Publication date: 2016-12-15
Also published as: KR102523681B1; TWI689581B; EP3305878A4; JPWO2016199718A1; CN107614663B; CN107614663A; EP3305878A1; JP6614510B2; TW201700721A; KR20180017079A

Abstract

[Problem] To provide an ester lubricating oil for refrigeration oils, the ester lubricating oil having excellent lubricating properties and heat resistance. [Solution] 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≤B_OH/(A_OH+B_OH)≤0.15 (2) [B_OH/(A_OH+B_OH)]/[B_mol/(A_mol+B_mol)]≤0.9 A_OH is the mol number of a terminal hydroxyl group derived from the component (A) in the ester. B_OH is the mol number of a terminal hydroxyl group derived from the component (B) in the ester. A_mol is the mol number of the constituent derived from the component (A) in the ester. B_mol is the mol number of the constituent derived from the component (B) in the ester.

Description

Ester for refrigeration oil and working fluid composition for refrigeration oil

The present invention relates to an ester for refrigerating machine oil having excellent lubricity and heat resistance. In addition, the present invention relates to an ester for refrigerating machine oil, which is used for a working fluid composition for refrigerating machine oil containing a non-chlorine fluorocarbon refrigerant or a natural refrigerant.

Air conditioners such as room air conditioners and packaged air conditioners, low-temperature equipment such as household refrigerator-freezers, industrial refrigerators, and car air conditioners such as hybrid cars and electric cars contain chlorine, which causes destruction of the ozone layer. Instead of chlorofluorocarbon refrigerant, R-- is a mixed refrigerant of 1,1,1,2-tetrafluoroethane (R-134a), pentafluoroethane (R-125), difluoromethane (R-32) and R-125. Hydrofluorocarbon (HFC) such as 410A is used as a refrigerant

However, although the above-mentioned HFC refrigerant has an ozone depletion coefficient of zero, it has a high global warming potential (GWP) of 1000 or more. Therefore, it is subject to regulations aimed at reducing the greenhouse effect, and the use of refrigerants with low GWP is being studied because use is restricted. For example, conversion to 2,3,3,3-tetrafluoropropene (HFO-1234yf) having a GWP of 4 and R-32 having a GWP of 675 alone has been promoted.

As the conversion to low GWP HFC refrigerants progresses, various types of esters for refrigerating machine oils based on polyol esters having high compatibility with these low GWP refrigerants have been proposed. In addition, when using refrigerants with high pressure, such as R-32 or a mixed refrigerant containing R-32 among alternative refrigerant candidates, the discharge temperature at the compressor becomes high, and the lubrication conditions in the compressor become more severe. Refrigerating machine esters with improved lubricity and stability have been proposed.

For example, Patent Document 1 discloses pentaerythritol, 2-ethylhexanoic acid, and 3 as esters having high stability even in a compressor that is operated in a thermally severe environment due to the use of a mixed refrigerant containing R-32. , 5,5,5-trimethylhexanoic acid-based lubricating oil for refrigerating machine oil is disclosed.
In the case of a hydrocarbon (HC) refrigerant, since there is no fluorine that enhances lubricity in the HC molecule, the effect of improving the lubricity by the refrigerant, such as HFC refrigerant, cannot be expected. Since the solubility in water is high and the viscosity of the oil is lowered, the lubrication conditions become more severe. Patent Document 2 proposes a complex ester having excellent lubricity and excellent heat resistance even under such severe lubrication conditions, and lubricity is improved by using 1,4-butanediol as a raw material. In addition, it is disclosed that heat resistance is improved by using monovalent alcohol as a raw material.

Japanese Patent Laid-Open No. 10-8084 WO2014 / 017596

However, as the equipment using refrigeration oil becomes more compact (decrease in the amount of refrigeration oil used per unit) and energy saving (extension of compressor operating time by inverter control) advances, the usage conditions of refrigeration oil further increase. It has become harsh. As a result, the refrigerating machine oil that is locally exposed to high-temperature conditions is thermally decomposed by frictional heat in the sliding part of the compressor, and the generated decomposition product may corrode metal parts or adversely affect the resin material. Therefore, there is a demand for the development of an ester for refrigerating machine oil that exhibits excellent lubricity and thermal stability even under more severe conditions.

An object of the present invention is to provide an ester lubricant for refrigerating machine oil having excellent lubricity and heat resistance.

As a result of intensive studies to solve the above problems, the present inventors have found that specific dihydric alcohols, dicarboxylic acids, and esters having monohydric alcohols as constituent components have excellent lubricity and heat resistance. As a result, the present invention has been completed.

That is, the present invention is as follows.
(1) A refrigerating machine ester obtained from the following component (A), component (B), component (C) and component (D),
0.1 to 0.4 mol of the component derived from the component (B) and 0.1 to 0.4 mol of the component derived from the component (C) with respect to 1.0 mol of the component derived from the component (A) in the ester. A ratio of 8 to 2.8 mol and a constituent component derived from the component (D) of 0.3 to 2.3 mol,
The ester has a hydroxyl value of 5 to 40 mgKOH / g and satisfies the formulas (1) and (2).

(A) Neopentyl glycol (B) A linear dihydric alcohol having 2 to 6 carbon atoms and having hydroxyl groups at both ends (C) A straight chain having 4 to 10 carbon atoms and having carboxyl groups at both ends Chain divalent carboxylic acid (D) Monohydric alcohol having 6 to 12 carbon atoms
0.08 ≦ _BOH / ( _AOH + _BOH ) ≦ 0.15 (1)
[ _BOH / ( _AOH + _BOH )] / [ _Bmol / ( _Amol + _Bmol )] ≦ 0.9
... (2)

(In the formula (1) and the formula (2),
A _OH is the number of moles of terminal hydroxyl groups from component (A) in the ester,
B _OH is the number of moles of terminal hydroxyl groups from component (B) in the ester,
A _mol is the number of moles of the component derived from the component (A) in the ester,
B _mol is the number of moles of the component derived from the component (B) in the ester)

(2) A working fluid composition for refrigerating machine oil, comprising a non-chlorine fluorocarbon refrigerant or a natural refrigerant and the refrigerating machine oil ester of (1).

In order to obtain the ester for refrigerating machine oil, preferably, component (A), component (B), component (C) and component (D) are subjected to a primary esterification reaction at a temperature of 100 to 150 ° C., Next, it is subjected to a secondary esterification reaction at a temperature of 150 ° C. to 250 ° C.

Since the ester for refrigerating machine oil of the present invention has high heat resistance, it can be suitably used for a compressor of a refrigerating and air-conditioning apparatus that particularly requires thermal stability. Moreover, since the ester for refrigerating machine oil of this invention has high compatibility with a non-chlorine type CFC refrigerant or a natural refrigerant, it can be suitably used for a working fluid composition for a refrigerating machine containing these refrigerants.

Hereinafter, the ester for refrigerating machine oil of the present invention will be described.
In the present specification, the numerical range defined using the symbol “˜” includes the numerical values at both ends (upper limit and lower limit) of “˜”. For example, “2 to 5” represents “2 or more and 5 or less”.

The ester for refrigerating machine oil of the present invention comprises neopentyl glycol (component (A)), a linear dihydric alcohol (component (B)) having 2 to 6 carbon atoms and having hydroxyl groups at both terminal carbons, A linear divalent carboxylic acid (component (C)) having 4 to 10 carbon atoms and having carboxyl groups at both ends of carbon and a monohydric alcohol having 6 to 12 carbon atoms (component (D)) are mixed. It can be obtained by esterification reaction.

Note that the terms component (A), component (B), component (C), and component (D) are general terms for convenience, and there may be one kind of compound belonging to each component, or it belongs to each component. Two or more compounds may be used. When each component contains two or more types of compounds, the amount of each component is the total amount of the two or more types of compounds belonging to that component.

As the neopentyl glycol of the component (A) used in the present invention, industrially available neopentyl glycol can be used, and the shape of neopentyl glycol is solid or liquid diluted with water. You can use things.

Component (B) is a linear dihydric alcohol having 2 to 6 carbon atoms and having hydroxyl groups at both terminal carbons, specifically ethylene glycol, 1,3-propanediol, 1,4-butane. Diol, 1,5-pentanediol, 1,6-hexanediol and the like can be mentioned. A linear divalent saturated alcohol is preferred, and 1,4-butanediol is particularly preferred. By component (B), an ester excellent in viscosity index, low-temperature stability, and lubricity can be obtained.

Component (C) is a linear divalent carboxylic acid having 4 to 10 carbon atoms and having carboxyl groups at both terminal carbons, and specifically includes succinic acid (4 carbon atoms), glutaric acid (5 carbon atoms). ), Adipic acid (carbon number 6), pimelic acid (carbon number 7), suberic acid (carbon number 8), azelaic acid (carbon number 9), sebacic acid (carbon number 10), and the like. It is preferable to use a linear divalent saturated 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.

Component (D) is a monohydric alcohol having 6 to 12 carbon atoms, and these may be either linear alcohols or branched alcohols. Specific examples include 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, 1-dodecanol, 2-ethylhexanol, 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. In particular, 2-ethylhexanol and 3,5,5-trimethylhexanol are preferably used.

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

When the amount of the component derived from the component (B) is less than 0.1 mol relative to 1.0 mol of the component derived from the component (A), it is difficult to obtain the desired viscosity index and lubricity, and 0.4 mol. If it exceeds 1, the low-temperature stability of the ester deteriorates. Preferably, the amount of the component derived from component (B) can be 0.1 to 0.3 mol relative to 1.0 mol of the component derived from component (A).

When the amount of the component derived from the component (C) is less than 0.8 mol relative to 1.0 mol of the component derived from the component (A), it is difficult to obtain a high viscosity index. It becomes difficult to obtain sex. The amount of the component derived from component (C) is preferably 0.9 mol or more, and preferably 2.3 mol or less, relative to 1.0 mol of the component derived from component (A).

When the amount of the component derived from the component (D) is 0.3 to 2.3 mol relative to 1.0 mol of the component derived from the component (A), an ester having a viscosity suitable for refrigerating machine oil can be easily obtained. Become. The amount of the component derived from the component (D) is preferably 0.5 mol or more and preferably 2.1 mol or less with respect to 1.0 mol of the component derived from the component (A).

The molar ratio of each component described above is calculated by analysis by gas chromatography. 0.1 g of ester is diluted with 5 g of a toluene / methanol (80 wt% / 20 wt%) mixed solvent, then 0.3 g of 28% sodium methoxide methanol solution (Wako Pure Chemical Industries, Ltd.) is added, and the mixture is heated at 60 ° C. for 30 g. The ester is subjected to methanol decomposition by standing still. The obtained ester decomposition solution is analyzed by gas chromatography, and the peak area ratio of the obtained component (A), component (B), component (C), and component (D) is converted into a molar ratio. be able to. In addition, the component of an ester decomposition product can be identified by analyzing the gas chromatography of each component single.

In the ester of the present invention, the carboxyl group of the component (C) is converted into the components (A), (C) by adjusting the molar ratio of the components derived from the components (A), (B), (C), (D). B) or an ester synthesized so as to be blocked by (D), the terminal structure of which is an alkyl group derived from component (D), and the terminal structure of the ester is a hydroxyl group derived from component (A) as a minor component Groups, esters which are hydroxyl groups derived from component (B) are included.

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

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

By adopting such a structural design, when used as a refrigerating machine oil, it is difficult to cause hydrolysis or thermal decomposition, and an ester having excellent stability can be obtained.

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

0.08 ≦ _BOH / ( _AOH + _BOH ) ≦ 0.15 (1)

(A _OH is the number of moles of terminal hydroxyl groups from component (A) in the ester;
B _OH is the number of moles of terminal hydroxyl groups from component (B) in the ester. )

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

[ _BOH / ( _AOH + _BOH )] / [ _Bmol / ( _Amol + _Bmol )] ≦ 0.9
... (2)

(A _OH is the number of moles of terminal hydroxyl groups from component (A) in the ester;
B _OH is the number of moles of terminal hydroxyl groups from component (B) in the ester;
A _mol is the number of moles of the component derived from the component (A) in the ester,
B _mol is the number of moles of the component derived from the component (B) in the ester. )

The molecule of the formula (2) is [B _OH / (A _OH + B _OH )], which is shown in the formula (1), and the terminal hydroxyl group derived from the component (A) in the ester and the component The molar ratio of the terminal hydroxyl group derived from the component (B) to the sum of the terminal hydroxyl groups derived from (B) is shown.
On the other hand, the denominator of formula (2) is [B _mol / (A _mol + B _mol )], which is the sum of the component derived from component (A) and the component derived from component (B) in the ester. The molar ratio of the structural component derived from the component (B) is expressed.

Therefore, Formula (2) represents how much the molar ratio of the terminal hydroxyl group derived from the component (B) is smaller than the molar ratio of the component derived from the component (B) in the ester, In other words, it represents the degree of uneven distribution of the component (B) in the terminal structure relative to the entire ester structure.

In addition, each numerical value of Formula (1) (2) is measured as follows.
(Numerical value of formula (1) and numerical value of numerator of formula (2): B _OH / (A _OH + B _OH ))
^{Among the 1} H-NMR spectra, the integrated value of the α hydrogen peak (3.2 to 3.4 ppm) with respect to the hydroxyl group derived from the component (A) and the α hydrogen peak with respect to the hydroxyl group derived from the component (B) (3 (6 to 3.8 ppm), and the integral value of α hydrogen with respect to the hydroxyl group derived from component (B) was divided by the sum of the integral values.

(Numerical value of denominator of formula (2): B _mol / (A _mol + B _mol ))
The number of moles of each component derived from the component (A) and the component (B) was determined by the gas chromatography analysis, and the molar ratio was calculated.

In component (A), hydrogen is not bonded to the β carbon (β hydrogen is not present), and therefore the terminal hydroxyl group generated at the end of the ester structure is the terminal structure derived from component (A) derived from component (B). Excellent heat resistance compared to the terminal structure. That is, an ester having more ester structure terminals derived from the component (A) is superior in heat resistance as compared to an ester that is not. As a result, the ester having more excellent heat resistance can be obtained by setting the molar ratio of the hydroxyl group derived from the component (B) to the total hydroxyl groups to be 0.15 or less. Excellent lubricity and heat resistance when the molar ratio of the terminal hydroxyl group derived from component (B) to the total of the terminal hydroxyl group derived from component (A) and the terminal hydroxyl group derived from component (B) is 0.08 to 0.15. Esters are easily obtained. From this viewpoint, the molar ratio is more preferably 0.09 or more, and further preferably 0.14 or less.

Furthermore, the ester unevenly distributed so that the molar ratio of the terminal hydroxyl group derived from the component (B) is smaller than the molar ratio of the component derived from the component (B) in the ester is superior in heat resistance. Become. The uneven distribution degree of the component (B) in the terminal structure can be represented by the molar ratio of the terminal hydroxyl group derived from the component (B) to the molar ratio of the component derived from the component (B) in the ester. By setting it to 9 or less, an ester having more excellent heat resistance can be obtained. This value is 0.9 or less, but more preferably 0.8 or less. The lower limit of this value is not particularly limited, but is preferably 0.2 or more, more preferably 0.3 or more, and still more preferably 0.5 or more.

The ester of the present invention comprises all hydroxyl groups in the ester with respect to the molar ratio of the component derived from the component (B) to the sum of the component derived from the component (A) and the component derived from the component (B) in the ester. The ester which reduced the molar ratio of the hydroxyl group derived from the component (B) in the above, and the ester satisfying the formula (1) and the formula (2) is an ester having further excellent heat resistance for the reasons described above.

In producing the ester, first, the above components (A), (B), (C) and (D) are all charged into an appropriate reactor, and an esterification reaction is carried out under normal pressure and nitrogen atmosphere. The esterification reaction can be usually carried out at 150 to 250 ° C. in order to efficiently remove the reaction product water. However, from the viewpoint of obtaining an ester having better heat resistance, first, a primary esterification reaction is performed at 100 to 150 ° C. Thereafter, a secondary esterification reaction is carried out at 150 ° C. to 250 ° C.

The primary esterification reaction is preferably performed at 100 to 140 ° C., more preferably 100 to 130 ° C., whereby an ester having excellent heat resistance can be easily obtained. The primary esterification reaction is preferably performed for 1 to 10 hours, more preferably 2 to 8 hours, whereby an ester having excellent heat resistance can be easily obtained.

The secondary esterification reaction is preferably performed at 160 to 260 ° C, more preferably 180 to 250 ° C. At this time, the secondary esterification reaction is carried out until the acid value becomes 10 mgKOH / g or less, preferably 5 mgKOH / g or less, more preferably 2 mgKOH / g.
The esterification reaction may be performed using a Bronsted acid catalyst or a Lewis acid catalyst, but is preferably performed without a catalyst.

After the esterification reaction, the excess component (D) is distilled off under reduced pressure to obtain a crude ester. Furthermore, the target ester for refrigerating machine oil can be obtained by refining the crude ester with an adsorbent.

The kinematic viscosity at 40 ° C. of the ester for refrigerating machine oil of the present invention is preferably 20 to 500 mm ² / s. More preferably, it is 20 to 300 mm ² / s, still more preferably 20 to 250 mm ² / s, and most preferably 20 to 180 mm ² / s. The hydroxyl value is preferably 5 to 40 mgKOH / g, more preferably 15 to 35 mgKOH / g.

The ester for refrigerating machine oil of the present invention can be used alone as a base oil, or can be used by mixing with other base oils. Also known additives such as phenolic antioxidants, metal deactivators such as benzotriazole, thiadiazole or dithiocarbamate, acid scavengers such as epoxy compounds or carbodiimides, additives such as phosphorus extreme pressure agents Can be appropriately blended depending on the purpose.

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

Specific examples of the hydrofluorocarbon (HFC) refrigerant include 1,1,1,2-tetrafluoroethane (R-134a), pentafluoroethane (R-125), difluoroethane (R-32), trifluoromethane ( R-23), 1,1,2,2-tetrafluorofluoroethane (R-134), 1,1,1-trifluoroethane (R-143a), 1,1-difluoroethane (R-152a), etc. Any one or a mixture of two or more is preferable. Examples of the mixed refrigerant include R-407C (R-134a / R-125 / R-32 = 52/25/23 mass%), 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% by mass) R-410B (R-32 / R-125 = 45/55% by mass). Among these, a refrigerant containing at least one of R-134a and R-32 is particularly preferable, and a single R-32 refrigerant is more preferable.

Specific examples of the hydrofluoroolefin (HFO) refrigerant include 1,2,3,3,3-pentafluoropropene (HFO-1225ye) and 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) It is preferable that they are 1 type, or a mixture of 2 or more types. From the viewpoint of the physical properties of the refrigerant, one or more selected from HFO-1225ye, HFO-1234ze, and HFO-1234yf are preferable.

In addition, examples of the hydrocarbon (HC) refrigerant include propane (R290) and isobutane (R600a) and mixtures thereof, and examples of the natural refrigerant include ammonia and carbon dioxide. Particularly preferred are R290, R600 and carbon dioxide.

The working fluid composition for refrigerating machine oil usually has a mass ratio of 10:90 to 90:10 of the refrigerating machine ester according to the present invention and a non-chlorine fluorocarbon refrigerant or a natural refrigerant. If the mass ratio of the refrigerant is within this range, the working fluid composition has an appropriate viscosity, which is preferable because it has excellent lubricity and high refrigeration efficiency.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

In addition, the various analysis of the ester for refrigerator oil obtained in the Example and the comparative example was analyzed in accordance with the following method.

Acid value: Measured according to JIS K2501.
Hydroxyl value: Measured according to JIS K0070.
Kinematic viscosity: Measured according to JIS K2283.

Production of Example 1 124 g (1.19 mol) neopentyl glycol, 30 g (0.34 mol) 1,4-butanediol, 355 g (2.43 mol) adipic acid, 339 g (2.35 mol) 3,5,5-trimethylhexanol ) Was charged into a four-necked flask and reacted at normal pressure for 3 hours while distilling off the reaction water at 120 ° C. in a nitrogen atmosphere. Thereafter, the reaction was continued for 7 hours at 200 ° C. until the acid value became 2 or less. Subsequently, excess 3,5,5-trimethylhexanol was distilled off at 200 ° C. under reduced pressure of 1 to 5 kPa to obtain a crude ester. The crude ester was cooled, and acid clay and silica-alumina-based adsorbent were added to each so as to be 1.0% by mass of the theoretically obtained ester amount, followed by adsorption treatment. The adsorption treatment temperature, pressure, and adsorption treatment time were 100 ° C., 1 to 5 kPa, and 2 hours. Finally, filtration was performed using a 1-micron filter to obtain the target ester.

Production of Example 2 180 g (1.73 mol) neopentyl glycol, 25 g (0.28 mol) 1,4-butanediol, 360 g (2.47 mol) adipic acid, 256 g (1.78 mol) 3,5,5-trimethylhexanol ) In a four-necked flask, and the reaction was carried out at normal pressure for 4 hours while distilling off the reaction water at 115 ° C. in a nitrogen atmosphere. The subsequent steps were performed in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 3 Neopentyl glycol 205 g (1.97 mol), 1,4-butanediol 26 g (0.28 mol), adipic acid 373 g (2.55 mol), 3,5,5-trimethylhexanol 217 g (1.50 mol) ) Was charged into a four-necked flask and reacted at normal pressure for 3 hours while distilling off the reaction water at 125 ° C. in a nitrogen atmosphere. The subsequent steps were performed in the same manner as in Example 1 to obtain the target ester.

Production of Example 4 174 g (1.66 mol) neopentyl glycol, 46 g (0.51 mol) 1,4-butanediol, 373 g (2.55 mol) adipic acid, 238 g (1.65 mol) 3,5,5-trimethylhexanol ) Was charged into a four-necked flask and reacted at normal pressure for 4 hours while distilling off the reaction water at 120 ° C. in a nitrogen atmosphere. The subsequent steps were performed in the same manner as in Example 1 to obtain the target ester.

Manufacture of Example 5 129 g (1.23 mol) of neopentylglycol, 28 g (0.26 mol) of 1,5-pentanediol, 393 g (2.25 mol) of suberic acid, and 300 g (2.30 mol) of n-octanol were used in four necks. The flask was charged and reacted at normal pressure for 5 hours while distilling off the reaction water at 120 ° C. in a nitrogen atmosphere. The subsequent steps were performed in the same manner as in Example 1 to obtain the target ester.

Production of Example 6 Neopentyl glycol 215 g (2.07 mol), 1,3-propanediol 22 g (0.29 mol), adipic acid 385 g (2.64 mol), 3,5,5-trimethylhexanol 214 g (1.49 mol) ) Was charged into a four-necked flask and reacted at normal pressure for 4 hours while distilling off the reaction water at 120 ° C. in a nitrogen atmosphere. The subsequent steps were performed in the same manner as in Example 1 to obtain the target ester.

Preparation of Example 7 Neopentyl glycol 211 g (2.03 mol), 1,6-hexanediol 42 g (0.36 mol), adipic acid 385 g (2.64 mol), 3,5,5-trimethylhexanol 206 g (1.43 mol) ) Was charged into a four-necked flask and reacted at normal pressure for 5 hours while distilling off the reaction water at 115 ° C. in a nitrogen atmosphere. The subsequent steps were performed in the same manner as in Example 1 to obtain the target ester.

Production of Comparative Example 1 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-trimethylhexanol 238 g (1.65 mol) ) Was added to a four-necked flask and the reaction was continued for 7 hours at atmospheric pressure until the acid value became 2 or less while distilling off the reaction water at 200 ° C. in a nitrogen atmosphere. Subsequently, excess 3,5,5-trimethylhexanol was distilled off at 200 ° C. under reduced pressure of 1 to 5 kPa to obtain a crude ester. The crude ester was cooled, and acid clay and silica-alumina-based adsorbent were added to each so as to be 1.0% by mass of the theoretically obtained ester amount, followed by adsorption treatment. The adsorption treatment temperature, pressure, and adsorption treatment time were 100 ° C., 1 to 5 kPa, and 2 hours. Finally, filtration was performed using a 1-micron filter to obtain the target ester.

Preparation of Comparative Example 2 104 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 charged into a four-necked flask, and 200 ° C. under a nitrogen atmosphere. The reaction was carried out at normal pressure for 3 hours while distilling off the reaction water until an acid value of 270 or less was obtained to obtain an ester intermediate. To this ester intermediate, 361 g (2.50 mol) of 3,5,5-trimethylhexanol was further added, and the reaction was continued for 7 hours until the acid value became 2 or less. Subsequently, excess 3,5,5-trimethylhexanol was distilled off at 200 ° C. under reduced pressure of 1 to 5 kPa to obtain a crude ester. The crude ester was cooled, and acid clay and silica-alumina-based adsorbent were added to each so as to be 1.0% by mass of the theoretically obtained ester amount, followed by adsorption treatment. The adsorption treatment temperature, pressure, and adsorption treatment time were 100 ° C., 1 to 5 kPa, and 2 hours. Finally, filtration was performed using a 1-micron filter to obtain the target ester.

Heat resistance (heating test)
The heat resistance of the ester for refrigerating machine oil was evaluated by carrying out a heating test on the ester for refrigerating machine oil. In the heat resistance test, heating was performed in a thermostatic bath at 130 ° C. for 72 hours in an air atmosphere, and the acid value of the ester for refrigerating machine oil after heating was measured.

Lubricity (SRV test)
About the said ester for refrigerator oil, lubricity was evaluated with the SRV test machine. The SRV test was performed with a ball / disk, and test pieces made of SUJ-2 were used. The test conditions were a test temperature of 60 ° C., a load of 100 N, an amplitude of 1 mm, and a vibration frequency of 50 Hz, and the wear scar diameter after a test time of 25 minutes was measured.

The production conditions of Examples 1 to 7 and Comparative Examples 1 and 2 are summarized in Tables 1 and 2, and the physical properties, heat resistance, and lubricity are summarized in Tables 3 and 4. In addition, Table 1 and Table 2 describe the charging ratio of each component, and Tables 3 and 4 list the measured values of the molar ratio of the constituent components derived from each component in the produced ester.

As shown in Tables 1 to 4, the esters of Examples 1 to 7 have excellent lubricity and excellent heat resistance, so that they are not easily deteriorated even under severe lubricating conditions in the compressor. It can be used in. In addition, since the increase in the acid value in the heating test is suppressed, the generation of decomposition products that cause corrosion such as metals in the compressor can also be suppressed.

On the other hand, in Comparative Examples 1 and 2, since the increase in the acid value was large unlike the ester of the Example, it was confirmed that the decomposition of the ester by the heating test was advanced as compared with the Example.

Claims

An ester for refrigerating machine oil obtained from the following component (A), component (B), component (C) and component (D),
0.1 to 0.4 mol of the component derived from the component (B) and 0.1 to 0.4 mol of the component derived from the component (C) with respect to 1.0 mol of the component derived from the component (A) in the ester. A ratio of 8 to 2.8 mol and a constituent component derived from the component (D) of 0.3 to 2.3 mol,
An ester for refrigerating machine oil, wherein the ester has a hydroxyl value of 5 to 40 mg KOH / g and satisfies the formulas (1) and (2).

(A) Neopentyl glycol (B) A linear dihydric alcohol having 2 to 6 carbon atoms and having hydroxyl groups at both ends (C) A straight chain having 4 to 10 carbon atoms and having carboxyl groups at both ends Chain divalent carboxylic acid (D) Monohydric alcohol having 6 to 12 carbon atoms
0.08 ≦ BOH / ( AOH + BOH ) ≦ 0.15 (1)

[ BOH / ( AOH + BOH )] / [ Bmol / ( Amol + Bmol )] ≦ 0.9
... (2)

(In the formula (1) and the formula (2),
A OH is the number of moles of terminal hydroxyl groups from component (A) in the ester,
B OH is the number of moles of terminal hydroxyl groups from component (B) in the ester,
A mol is the number of moles of the component derived from the component (A) in the ester,
B mol is the number of moles of the component derived from the component (B) in the ester)
A working fluid composition for refrigerating machine oil, comprising a non-chlorine fluorocarbon refrigerant or a natural refrigerant and the refrigerating machine oil ester according to claim 1.