JPWO2013115160A1 - Mixed ester of mixed polyhydric alcohol and carboxylic acid - Google Patents

Abstract

The present invention relates to a mixed ester of a mixed polyhydric alcohol comprising pentaerythritol and dipentaerythritol represented by the formula (I) and a carboxylic acid containing isobutyric acid, wherein the mixed polyhydric alcohol contains pentaerythritol and diester. Provided is a mixed ester wherein the pentaerythritol molar ratio [pentaerythritol / dipentaerythritol] is in the range of 98/2 to 40/60, and the ratio of isobutyric acid to the carboxylic acid is in the range of 35 to 85 mol%. The mixed ester has excellent lubricity and excellent compatibility with a difluoromethane refrigerant while ensuring a viscosity range necessary for the refrigerator oil, and is used for refrigerator oil and the like.

Description

  The present invention relates to a mixed ester used for industrial lubricating oil such as refrigerator oil.

  In recent years, hydrofluorocarbons (HFCs) having zero ozone depletion coefficient and lower global warming potential (GWP) have been used as refrigerants for refrigerators. The difluoromethane refrigerant (HFC-32) is a refrigerant in which GWP is currently used [R-410A (mixture of difluoromethane and pentafluoroethane), R-407C (difluoromethane, pentafluoroethane, 1,1,1 , 2-tetrafluoroethane, etc.)] and the coefficient of performance (COP) is improved by about 5 to 13% relative to R-410A, R-407C, etc. It is a preferable refrigerant from the viewpoint of energy saving (Non-Patent Document 1).

  In the refrigerant circulation cycle of the refrigerator, the refrigerant oil is circulated in the cycle together with the refrigerant that normally lubricates the refrigerant compressor. Therefore, the refrigerating machine oil is required to have compatibility with the refrigerant, and since it is used for the purpose of lubricating the operating part of the refrigerating machine, the lubricating performance is naturally important. When the refrigeration oil undergoes phase separation, the refrigeration oil discharged from the refrigerant compressor tends to stay in the cycle. This causes problems such as closing the expansion mechanism. For lubrication performance in the refrigerator, it is particularly important to maintain the oil film in the compressor at a high temperature, and the viscosity of the refrigerator oil is important for maintaining the oil film. If the viscosity is low, the oil film is thin and lubrication is liable to occur, and if the viscosity is high, the efficiency of heat exchange decreases (Patent Document 1, Patent Document 2, Patent Document 3).

  Patent Document 2 discloses an ester of pentaerythritol and a fatty acid used in a refrigerating machine oil for a difluoromethane refrigerant, but the compatibility of the ester with the difluoromethane refrigerant is not sufficient.

  Patent Document 3 describes various carboxylic acid esters that are useful as cooling liquids for refrigerators and air conditioners. Among them, pentaerythritol, dipentaerythritol, and a carboxylic acid containing isobutyric anhydride are reacted. A liquid composition containing the ester thus obtained is disclosed. However, the compatibility of the ester with the difluoromethane refrigerant is not described, and the viscosity of the ester is not within the viscosity range required for refrigerating machine oil.

Japanese Patent No. 3429031 JP 2002-129177 A JP-A-6-41575

“Lubrication Economy”, June 2004 (No. 460), p. 17

  An object of the present invention is to provide a mixed ester for use in a refrigerating machine oil or the like having an excellent compatibility with a difluoromethane refrigerant while ensuring a viscosity range necessary for the refrigerating machine oil.

で表されるジペンタエリスリトールからなる混合多価アルコールとイソ酪酸を含有するカルボン酸との混合エステルであって、前記混合多価アルコールにおけるペンタエリスリトールとジペンタエリスリトールのモル比［ペンタエリスリトール／ジペンタエリスリトール］が９８／２〜４０／６０の範囲であり、前記カルボン酸にしめるイソ酪酸の割合が３５〜８５モル％の範囲である混合エステル。
［２］前記カルボン酸がイソ酪酸と３，５，５−トリメチルヘキサン酸および／または２−エチルヘキサン酸とを含有する［１］に記載の混合エステル。
［３］前記カルボン酸がイソ酪酸と３，５，５−トリメチルヘキサン酸とからなる［１］に記載の混合エステル。
［４］前記カルボン酸がイソ酪酸と２−エチルヘキサン酸とからなる［１］に記載の混合エステル。The present invention provides the following [1] to [4].
[1] Pentaerythritol and formula (I)

A mixed ester of a mixed polyhydric alcohol composed of dipentaerythritol and a carboxylic acid containing isobutyric acid represented by the formula: wherein the molar ratio of pentaerythritol and dipentaerythritol in the mixed polyhydric alcohol [pentaerythritol / dipenta Erythritol] is in the range of 98/2 to 40/60, and the ratio of isobutyric acid to the carboxylic acid is in the range of 35 to 85 mol%.
[2] The mixed ester according to [1], wherein the carboxylic acid contains isobutyric acid and 3,5,5-trimethylhexanoic acid and / or 2-ethylhexanoic acid.
[3] The mixed ester according to [1], wherein the carboxylic acid is composed of isobutyric acid and 3,5,5-trimethylhexanoic acid.
[4] The mixed ester according to [1], wherein the carboxylic acid is composed of isobutyric acid and 2-ethylhexanoic acid.

  ADVANTAGE OF THE INVENTION By this invention, the mixed ester used for the refrigerating machine oil etc. which have the outstanding compatibility with a difluoromethane refrigerant | coolant etc. can be provided, ensuring the viscosity range required as a refrigerating machine oil.

で表されるジペンタエリスリトールからなる混合多価アルコールと、イソ酪酸を含有するカルボン酸との混合エステルであって、前記混合多価アルコールにおけるペンタエリスリトールとジペンタエリスリトールのモル比［ペンタエリスリトール／ジペンタエリスリトール］が９８／２〜４０／６０の範囲であり、前記カルボン酸にしめるイソ酪酸の割合が３５〜８５モル％の範囲である混合エステルである。ここで、混合エステルとは、多価アルコールを複数種用いてエステル化して得られる化合物を意味する。
以下、前記式（Ｉ）で表されるジペンタエリスリトールを、ジペンタエリスリトールという。The mixed esters of the present invention are pentaerythritol and formula (I)

A mixed ester of a mixed polyhydric alcohol composed of dipentaerythritol and a carboxylic acid containing isobutyric acid, the molar ratio of pentaerythritol and dipentaerythritol in the mixed polyhydric alcohol [pentaerythritol / di Pentaerythritol] is a mixed ester having a range of 98/2 to 40/60 and a ratio of isobutyric acid to the carboxylic acid in a range of 35 to 85 mol%. Here, the mixed ester means a compound obtained by esterification using a plurality of polyhydric alcohols.
Hereinafter, dipentaerythritol represented by the formula (I) is referred to as dipentaerythritol.

The “mixed ester” in the present invention includes the following (i) to (iii):
(I) an ester of pentaerythritol in which the constituent carboxylic acid in the same molecule includes both isobutyric acid and other carboxylic acids other than isobutyric acid; and the constituent carboxylic acid in the same molecule of other carboxylic acids other than isobutyric acid and isobutyric acid (Ii) ester of pentaerythritol and carboxylic acid containing isobutyric acid, ester consisting of pentaerythritol and other carboxylic acid other than isobutyric acid, dipentaerythritol and isopentyl Mixtures of esters with carboxylic acids containing butyric acid and esters of dipentaerythritol with other carboxylic acids other than isobutyric acid (iii) The embodiments of the mixtures of (i) and (ii) above are included The
Note that the mixed ester of the present invention may contain, as impurities, a partial ester in which a part of the hydroxyl group of the mixed polyhydric alcohol is not esterified and remains as a hydroxyl group.

  Since the mixed polyhydric alcohol constituting the mixed ester of the present invention comprises pentaerythritol and dipentaerythritol, the mixed ester of the present invention has excellent compatibility with difluoromethane refrigerant, excellent lubricity, and sufficient viscosity-temperature characteristics. It has a good balance of characteristics such as sufficient low-temperature characteristics.

  In the mixed polyhydric alcohol constituting the mixed ester of the present invention, the molar ratio of pentaerythritol and dipentaerythritol [pentaerythritol / dipentaerythritol ratio] is in the range of 98/2 to 40/60, 97/3 A range of 70/30 is preferred. When the molar ratio of pentaerythritol and dipentaerythritol is 98/2 or less, the mixed ester can improve the low temperature characteristics and compatibility with the difluoromethane refrigerant while ensuring the necessary viscosity range. On the other hand, when the molar ratio is 40/60 or more, the mixed ester can maintain excellent lubricity while ensuring a necessary viscosity range.

Since the carboxylic acid constituting the mixed ester of the present invention contains isobutyric acid, the mixed ester of the present invention has excellent compatibility with difluoromethane refrigerant, excellent lubricity, sufficient viscosity-temperature characteristics, sufficient Good balance of properties such as low-temperature properties.
The proportion of isobutyric acid included in the carboxylic acid constituting the mixed ester of the present invention is in the range of 35 to 85 mol%, more preferably in the range of 40 to 80 mol%, and in the range of 60 to 80 mol%. Is more preferable. The said characteristic will not be acquired if this ratio of the isobutyric acid made into the carboxylic acid which comprises mixed ester remove | deviates from the range of 35-85 mol%. When the proportion of isobutyric acid is more than 85 mol%, the low temperature characteristics of the mixed ester are deteriorated.

  In the carboxylic acid constituting the mixed ester of the present invention, as other carboxylic acid other than isobutyric acid, for example, acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, Linear aliphatic monocarboxylic acid such as dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, 2-methylbutyric acid, 3-methylbutyric acid, 2,2, -dimethylpropanoic acid, 2-ethylbutyric acid, 2-methylpentane Acid, 4-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethyl-2-methylbutyric acid, 2,2-dimethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3 -Ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethyl-2-methylpentanoic acid, 2-methyloctanoic acid, 2, -Branched aliphatic monocarboxylic acids such as dimethylheptanoic acid, isotridecanoic acid, isostearic acid, etc. Among them, butyric acid, pentanoic acid, hexanoic acid, heptanoic acid, 2-methylbutyric acid, 3-methylbutyric acid, 2, 2, -dimethylpropanoic acid, 2-ethylbutyric acid, 2-methylpentanoic acid, 4-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, or 3,5,5-trimethyl Hexanoic acid is preferred, butyric acid, pentanoic acid, 2-methylbutyric acid, 3-methylbutyric acid, 2-ethylhexanoic acid, or 3,5,5-trimethylhexanoic acid is more preferred, 2-ethylhexanoic acid, or 3,5 More preferred is 5,5-trimethylhexanoic acid. Moreover, you may combine 2 or more types of these preferable carboxylic acid.

When the carboxylic acid constituting the mixed ester of the present invention is a carboxylic acid containing isobutyric acid and 3,5,5-trimethylhexanoic acid and / or 2-ethylhexanoic acid, the mixed ester of the present invention is a difluoromethane refrigerant. Other carboxylic acids can be contained in a content that does not impair excellent properties such as compatibility with the other.
Molar ratio of other carboxylic acids to the sum of isobutyric acid and 3,5,5-trimethylhexanoic acid and / or 2-ethylhexanoic acid [other carboxylic acids / (isobutyric acid and 3,5,5-trimethylhexanoic acid and // 2-ethylhexanoic acid) ratio] is preferably in the range of 0/100 to 50/50, more preferably 0/100.

  When the carboxylic acid constituting the mixed ester of the present invention is a carboxylic acid composed of isobutyric acid and 3,5,5-trimethylhexanoic acid, or isobutyric acid and 2-ethylhexanoic acid, the mixed ester of the present invention is It has particularly well-balanced properties such as excellent compatibility with difluoromethane refrigerant, excellent lubricity, sufficient viscosity-temperature characteristics, and sufficient low-temperature characteristics.

When the carboxylic acid constituting the mixed ester of the present invention is a carboxylic acid composed of isobutyric acid and 3,5,5-trimethylhexanoic acid, the molar ratio of isobutyric acid to 3,5,5-trimethylhexanoic acid [iso Butyric acid / 3,5,5-trimethylhexanoic acid ratio] is in the range of 35/65 to 85/15.
When the carboxylic acid constituting the mixed ester of the present invention is a carboxylic acid composed of isobutyric acid and 2-ethylhexanoic acid, the molar ratio of isobutyric acid to 2-ethylhexanoic acid [ratio of isobutyric acid / 2-ethylhexanoic acid] Is in the range of 35/65 to 85/15.

  The mixed polyhydric alcohol composed of pentaerythritol and dipentaerythritol constituting the mixed ester of the present invention can be obtained as a mixture or by mixing pentaerythritol and dipentaerythritol obtained as a commercial product, respectively. Can be obtained.

  The mixed ester of the present invention can be produced, for example, by reacting pentaerythritol, dipentaerythritol, isobutyric acid, and optionally other carboxylic acid at 120 to 300 ° C. for 5 to 60 hours.

  A catalyst may be used in the reaction, and examples of the catalyst include mineral acids, organic acids, Lewis acids, organic metals, solid acids and the like. Specific examples of the mineral acid include hydrochloric acid, hydrofluoric acid, sulfuric acid, phosphoric acid, nitric acid and the like. Specific examples of the organic acid include p-toluenesulfonic acid, benzenesulfonic acid, butanesulfonic acid, propanesulfonic acid, ethanesulfonic acid, methanesulfonic acid and the like. Specific examples of the Lewis acid include boron trifluoride, aluminum chloride, tin tetrachloride, titanium tetrachloride and the like. Specific examples of the organic metal include tetrapropoxy titanium, tetrabutoxy titanium, tetrakis (2-ethylhexyloxy) titanium, and the like. Specific examples of the solid acid include a cation exchange resin.

  The sum of the amount of isobutyric acid used and the amount of other carboxylic acids used is preferably 1.1 to 1.4 times the mole of the sum of the hydroxyl groups of pentaerythritol and dipentaerythritol used.

  A solvent may be used in the reaction, and examples of the solvent include hydrocarbon solvents such as benzene, toluene, xylene, hexane, heptane, isohexane, isooctane, isononane, and decane.

  It is preferable to carry out the reaction while removing water produced by the reaction from the reaction mixture. When water produced by the reaction is removed from the reaction mixture, isobutyric acid and other carboxylic acids may be removed from the reaction mixture at the same time.

  Also, from the difference in reactivity of isobutyric acid and other carboxylic acids with respect to pentaerythritol and / or dipentaerythritol, the molar ratio of pentaerythritol and dipentaerythritol constituting the resulting mixed ester, isobutyric acid and other The molar ratio of the carboxylic acid may be different from the molar ratio in the amount used to produce the mixed ester.

  The carboxylic acid constituting the mixed ester of the present invention may be derived from a carboxylic acid anhydride or a carboxylic acid halide, and by using these in the reaction, an unreacted hydroxyl group can be efficiently esterified. . Carboxylic anhydride is a compound in which two molecules of carboxylic acid lose one molecule of water and condense. Carboxylic acid halides are those in which the hydroxyl group contained in the carboxyl group of the carboxylic acid is substituted with halogen. Depending on the type of halogen, there are acid fluorides, acid chlorides, acid bromides, acid iodides, and the like.

  After the reaction, if necessary, the mixed ester of the present invention can be used in a method commonly used in organic synthetic chemistry (washing with water and / or aqueous alkali solution, treatment with activated carbon, adsorbent, etc., various chromatography, distillation, etc.). It may be purified.

  The mixed ester of the present invention has excellent compatibility with a difluoromethane solvent, excellent lubricity, sufficient viscosity-temperature characteristics, sufficient low temperature characteristics, and the like.

  The viscosity-temperature characteristic is a change in kinematic viscosity with respect to a temperature change of an oil agent such as a lubricating oil. An oil agent with good viscosity-temperature characteristics has a small viscosity change with respect to a temperature change, while a poor oil agent has an abrupt increase in viscosity at a low temperature range or an kinematic viscosity lower than expected at a high temperature range. It is. Generally, the viscosity-temperature characteristic is expressed as a viscosity index, and it can be said that the higher the numerical value, the better the viscosity-temperature characteristic. Moreover, the viscosity characteristic in a low temperature region is also called low temperature fluidity, and is represented by a pour point, a freezing point, a channel point, and the like.

  The pour point refers to the lowest temperature at which the oil agent flows when the oil agent such as lubricating oil is cooled according to the method of Japanese Industrial Standard (JIS) K2269. An oil agent with a low pour point does not deteriorate its fluidity even in low temperature environments such as in winter or in cold regions, or when operating as an evaporator in a refrigerator at low temperatures when used as refrigeration oil. It is preferable in that it does not cause malfunction of the equipment using the device.

  In addition, when storing or using an oil agent such as lubricating oil for a long period of time in a place where the temperature difference is large, an oil agent that has no volatility in the high temperature range and does not solidify or precipitate in the low temperature range is preferable. Although there is no restriction | limiting in particular as a temperature range, The oil agent which can be used stably at about -20 degreeC at about 150 degreeC in a high temperature side and low temperature side is preferable. The characteristic that solidification and precipitation do not occur in the low temperature range is defined as the low temperature characteristic. Since the mixed ester of the present invention uses pentaerythritol and dipentaerythritol as a mixed polyhydric alcohol constituting the mixed ester, it is possible to suppress the occurrence of precipitates at low temperatures.

  Examples of the stability include thermal stability, oxidation stability, hydrolysis stability, shear stability and the like in lubricating oil applications.

  Examples of lubricity include friction reduction, wear reduction, extreme pressure, and the like. The lubricity can be improved by adding an additive to the lubricating base oil, or by using an ester having a viscosity range appropriate for the application and lubricating conditions as the lubricating base oil.

  The mixed ester of the present invention is excellent in compatibility with not only the conventional difluoromethane mixed solvent (R-410A, R-407C) but also the difluoromethane refrigerant alone.

  Compatibility with difluoromethane refrigerant is generally expressed using the two-layer separation temperature. It can be said that the lower the two-layer separation temperature, the better the compatibility on the low temperature side. However, as described above, an appropriate viscosity range is required for the ester from the viewpoint of lubricity. It is difficult to maintain or improve the compatibility while ensuring an appropriate viscosity. The mixed ester of the present invention uses both pentaerythritol and dipentaerythritol as the mixed polyhydric alcohol constituting the mixed ester, so that compatibility with the difluoromethane solvent is compatible while ensuring the necessary viscosity range. Can do. The compatibility between the refrigerant and the mixed ester has a correlation with the property of the ester.

When using a mixed ester of the present invention to the refrigerator oil, kinematic viscosity at 40 ° C. of the mixed ester is preferably in the range of 20 to 100 mm ² / sec, more is in the range of 30~95mm ² / sec preferable.

  When the mixed ester of the present invention is used in refrigerating machine oil, if the residual amount of hydroxyl groups in the mixed ester is large, the refrigerating machine oil becomes cloudy at low temperature and undesired phenomena occur such as blocking the refrigeration cycle capillary device. The hydroxyl value of the mixed ester is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less.

  The mixed ester of the present invention can be used not only for refrigerating machine oil, but also for engine oil, gear oil, motor oil used for hybrid vehicles and electric vehicles, grease, metal parts cleaning agents, plasticizers, and the like.

  Examples of the refrigerating machine oil using the mixed ester of the present invention include a refrigerating machine oil containing a mixed ester and a lubricating oil additive. In the refrigerating machine oil using the mixed ester of the present invention, the mixed ester is used as a lubricating base oil.

  Examples of additives for lubricants include detergent dispersants, antioxidants, wear reducers (antiwear agents, anti-seizure agents, extreme pressure agents, etc.), friction modifiers, oiliness agents, acid scavengers, metal non-additives. Activators, rust inhibitors, pour point depressants, viscosity index improvers, thickeners, antifoaming agents and the like can be mentioned. The content of these additives is preferably 0.001 to 5% by weight in the refrigerating machine oil.

  You may use together the mixed ester of this invention, and another lubricating base oil. Examples of other lubricating base oils include mineral oils and synthetic base oils.

  Examples of the mineral oil include paraffinic crude oil, intermediate crude oil, and naphthenic crude oil. Further, refined oils obtained by refining them by distillation or the like can also be used.

  Synthetic base oils include, for example, poly-α-olefins (polybutene, polypropylene, α-olefin oligomers having 8 to 14 carbon atoms, etc.), aliphatic esters (fatty acid monoesters, polyhydric alcohols) other than the tetraesters of the present invention. Fatty acid ester, aliphatic polybasic acid ester, etc.), aromatic ester (aromatic monoester, aromatic ester of polyhydric alcohol, aromatic polybasic acid ester, etc.), polyalkylene glycol, polyvinyl ether, polyphenyl ether, alkylbenzene , Polycarbonate, synthetic naphthene and the like.

  Further, the mixed ester of the present invention is excellent in the ability to dissolve additives for lubricating oil such as metal deactivators such as benzotriazole and silicone antifoaming agents. The additive for lubricating oil is used by being dissolved in the lubricating oil, for example, in order to extend the life of the lubricating oil, equipment using the lubricating oil, and the like. The additive for lubricating oil generally has low solubility in mixed esters (Japanese Patent Laid-Open No. 10-259394). Benzotriazole has low solubility in mineral oil and / or synthetic oil (Japanese Patent Laid-Open No. 59-189195). However, for example, the solubility (25 ° C.) of benzotriazole in mixed ester 15 (Example 15 described later), which is a mixed ester of the present invention, is 0.04 g / g, which indicates high solubility of benzotriazole. On the other hand, the solubility (25 ° C.) of benzotriazole in the mixed ester A (Comparative Example 1 described later) was 0.02 g / g. The mixed ester of the present invention has excellent low-temperature fluidity and excellent wear resistance when benzotriazole is dissolved.

EXAMPLES Hereinafter, although an Example, a comparative example, a reference example, and a test example demonstrate this invention further more concretely, it is not limited to a following example.
The nuclear magnetic resonance spectrum was measured by the following measuring instrument and measuring method.
Measuring instrument: GSX-400 (400 MHz) manufactured by JEOL Ltd.
Measurement method: ¹ H-NMR, standard (tetramethylsilane), solvent (CDCl ₃ )

The nuclear magnetic resonance spectrum was measured for each of the mixed esters produced in Examples 1 to 24, Comparative Example 1 and Reference Examples 1 and 2, and the molar ratio of pentaerythritol and dipentaerythritol in the mixed ester was Calculated by the formula.
Pentaerythritol / dipentaerythritol = (integral value of peak R / 8) / (integral value of peak S / 4)
Here, the peak R corresponds to the peak of the hydrogen atom on the methylene group in pentaerythritol, and the peak S corresponds to the hydrogen atom on the methylene group bonded to the ether oxygen in dipentaerythritol.

For each of the mixed esters produced in the following Examples 1 to 16, Comparative Example 1 and Reference Examples 1 and 2, nuclear magnetic resonance spectra were measured, and isobutyric acid and 3,5,5-trimethylhexanoic acid in the mixed ester were measured. Was calculated by the following formula.
Isobutyric acid / 3,5,5-trimethylhexanoic acid = Integral value of peak T / Integral value of peak U Here, peak T corresponds to the peak of the hydrogen atom on the methine group in isobutyric acid, and peak U is 3,5 This corresponds to a hydrogen atom on the methine group in 1,5-trimethylhexanoic acid.

About each of the mixed ester manufactured in the following Examples 17-19, the nuclear magnetic resonance spectrum was measured and the molar ratio of isobutyric acid and 2-ethylhexanoic acid in mixed ester was computed with the following formula | equation.
Isobutyric acid / 2-ethylhexanoic acid = integrated value of peak T / integrated value of peak V Here, peak T is as defined above, and peak V corresponds to the peak of a hydrogen atom on the methine group in 2-ethylhexanoic acid. To do.

About the mixed ester produced in the following Example 20, a nuclear magnetic resonance spectrum was measured, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and 2-ethylhexanoic acid in the mixed ester was expressed by the following formula. Calculated.
Isobutyric acid / 3,5,5-trimethylhexanoic acid / 2-ethylhexanoic acid = integrated value of peak T / integrated value of peak U / integrated value of peak V Here, peak T, peak U and peak V are as defined above. It is.

The nuclear magnetic resonance spectrum was measured for the mixed ester produced in Example 21 below, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and butyric acid in the mixed ester was calculated according to the following formula.
Isobutyric acid / 3,5,5-trimethylhexanoic acid / butyric acid = integrated value of peak T / integrated value of peak U / (integrated value of peak W / 2)
Here, the peak T and the peak U have the same meaning as described above, and the peak W corresponds to the peak of a hydrogen atom on the methylene group at the α-position of the carbonyl group in butyric acid.

For each of the mixed esters produced in Examples 22 and 23 below, a nuclear magnetic resonance spectrum was measured, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and pentanoic acid in the mixed ester was expressed by the following formula: Calculated by
Isobutyric acid / 3,5,5-trimethylhexanoic acid / pentanoic acid = integrated value of peak T / integrated value of peak U / (integrated value of peak X / 2)
Here, the peak T and the peak U have the same meaning as described above, and the peak X corresponds to the peak of a hydrogen atom on the α-position methylene group of the carbonyl group in pentanoic acid.

For the mixed ester produced in Example 24 below, the nuclear magnetic resonance spectrum was measured, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and 2-methylbutyric acid in the mixed ester was calculated by the following formula: did.
Isobutyric acid / 3,5,5-trimethylhexanoic acid / 2-methylbutyric acid = integrated value of peak T / integrated value of peak U / integrated value of peak Y Here, peak T and peak U are as defined above, and peak Y corresponds to the peak of the hydrogen atom on the methine group in 2-methylbutyric acid.

[Example 1]
[The molar ratio of pentaerythritol to dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 97/3, and the molar ratio of isobutyric acid to 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 1) having a trimethylhexanoic acid ratio) of 81/19]
As an adsorbent, Kyoward 500 manufactured by Kyowa Chemical Industry Co., Ltd. was used.
As activated carbon, Shirahige P manufactured by Nippon Enviro Chemicals was used.
In a reactor equipped with a Dean-Stark trap, 153 g of pentaerythritol (1.1 mol, manufactured by Guangei Perstorp), 9 g of dipentaerythritol (0.04 mol, manufactured by Guangei Perstorp), 398 g (4.5 mol, Tokyo) Kasei Co., Ltd.) and 3,5,5-trimethylhexanoic acid 177 g (1.1 mol, manufactured by Kyowa Hakko Chemical Co., Ltd.) were added, and the mixture was degassed by bubbling nitrogen at room temperature for 30 minutes while stirring the mixture. .
The mixture was then stirred at 155 to 232 ° C. for 23 hours with nitrogen bubbling. After the reaction, the reaction product was stirred at 210 ° C. for 1 hour under a reduced pressure of 0.7 kPa to distill off unreacted carboxylic acid in the reaction product. The reaction product was washed at 90 ° C. for 1 hour with 300 mL of an alkaline aqueous solution containing sodium hydroxide twice as much as the acid value of the reaction product. The reaction product was then washed 3 times with 300 mL of water at 90 ° C. for 1 hour. Subsequently, the reaction product was dried at 110 ° C. for 1 hour under a reduced pressure of 0.7 kPa while performing nitrogen bubbling.
To the reaction product, 5.5 g of adsorbent (corresponding to 1.0% of the weight of the reaction product) and 5.5 g of activated carbon (corresponding to 1.0% of the weight of the reaction product) are added, and nitrogen bubbling is performed. Then, the reaction product was stirred at 110 ° C. for 2 hours under a reduced pressure of 0.7 kPa, and then filtered using a filter aid to obtain 370 g of mixed ester 1.

[Example 2]
[The molar ratio of pentaerythritol to dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 97/3, and the molar ratio of isobutyric acid to 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 2) having a trimethylhexanoic acid ratio) of 64/36]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 2 was obtained in the same manner as in Example 1 except that 0.03 / 3.01 / 2.01.

[Example 3]
[The molar ratio of pentaerythritol to dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 97/3, and the molar ratio of isobutyric acid to 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 3) having a trimethylhexanoic acid ratio) of 40/60]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 3 was obtained in the same manner as in Example 1 except that the ratio was 0.03 / 2.01 / 3.01.

[Example 4]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 90/10, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 4) having a trimethylhexanoic acid ratio) of 82/18]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 4 was obtained in the same manner as in Example 1 except that the ratio was 0.11 / 4.48 / 1.12.

[Example 5]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 90/10, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 5) having a trimethylhexanoic acid ratio) of 72/28]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 5 was obtained in the same manner as in Example 1 except that 0.11 / 3.92 / 1.68 was used.

[Example 6]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 90/10, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 6) having a trimethylhexanoic acid ratio) of 51/49]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 6 was obtained in the same manner as in Example 1 except that 0.11 / 2.80 / 2.80.

[Example 7]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 7) having a trimethylhexanoic acid ratio) of 81/19]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 7 was obtained in the same manner as in Example 1 except that the ratio was 0.18 / 4.86 / 1.21.

[Example 8]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 8) having a trimethylhexanoic acid ratio) of 58/42]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 8 was obtained in the same manner as in Example 1 except that 0.18 / 3.49 / 2.58 was used.

[Example 9]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 9) having a trimethylhexanoic acid ratio) of 50/50]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 9 was obtained in the same manner as in Example 1 except that 0.18 / 3.04 / 3.04.

[Example 10]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 10) having a trimethylhexanoic acid ratio) of 40/60]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 10 was obtained in the same manner as in Example 1 except that 0.18 / 2.43 / 3.64.

[Example 11]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 80/20, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 11) having a trimethylhexanoic acid ratio) of 82/18]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 11 was obtained in the same manner as in Example 1 except that 0.25 / 5.28 / 1.32.

[Example 12]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 80/20, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 12) having a trimethylhexanoic acid ratio) of 72/28]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 12 was obtained in the same manner as in Example 1 except that the ratio was changed to 0.25 / 4.62 / 1.98.

[Example 13]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 70/30, and the molar ratio of isobutyric acid to 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 13) having a trimethylhexanoic acid ratio) of 82/18]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 13 was obtained in the same manner as in Example 1 except that the ratio was 0.43 / 6.31 / 1.58.

[Example 14]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 70/30, and the molar ratio of isobutyric acid to 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 14) having a trimethylhexanoic acid ratio) of 60/40]
Molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3, · BR> T, 5-trimethylhexanoic acid used (ratio of pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid) The mixed ester 14 was obtained in the same manner as in Example 1 except that the ratio was changed to 1 / 0.43 / 4.73 / 3.15.

[Example 15]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 60/40, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 15) having a trimethylhexanoic acid ratio) of 82/18]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester 15 was obtained in the same manner as in Example 1 except that 0.67 / 7.68 / 1.92.

[Example 16]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 50/50, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester 16) having a trimethylhexanoic acid ratio) of 81/19]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / The mixed ester 16 was obtained in the same manner as in Example 1 except that the ratio was changed to 1.00 / 9.60 / 2.40.

[Example 17]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 2-ethylhexanoic acid (ratio of isobutyric acid / 2-ethylhexanoic acid) is 64 / 36 Production of mixed ester (mixed ester 17)]
Instead of 3,5,5-trimethylhexanoic acid, 2-ethylhexanoic acid is used, and the molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 2-ethylhexanoic acid used (pentaerythritol / dipentaerythritol / iso A mixed ester 17 was obtained in the same manner as in Example 1 except that the ratio of butyric acid / 2-ethylhexanoic acid was changed to 1 / 0.18 / 3.64 / 2.43.

[Example 18]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 2-ethylhexanoic acid (ratio of isobutyric acid / 2-ethylhexanoic acid) is 47. / 53 Production of mixed ester (mixed ester 18)]
Instead of 3,5,5-trimethylhexanoic acid, 2-ethylhexanoic acid is used, and the molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 2-ethylhexanoic acid used (pentaerythritol / dipentaerythritol / iso The mixed ester 18 was obtained in the same manner as in Example 1 except that the ratio of butyric acid / 2-ethylhexanoic acid was changed to 1 / 0.18 / 2.43 / 3.64.

[Example 19]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 70/30, and the molar ratio of isobutyric acid to 2-ethylhexanoic acid (ratio of isobutyric acid / 2-ethylhexanoic acid) is 62 / 38 Production of mixed ester (mixed ester 19)]
Instead of 3,5,5-trimethylhexanoic acid, 2-ethylhexanoic acid is used, and the molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 2-ethylhexanoic acid used (pentaerythritol / dipentaerythritol / iso The mixed ester 19 was obtained in the same manner as in Example 1 except that the ratio of butyric acid / 2-ethylhexanoic acid was changed to 1 / 0.43 / 4.73 / 3.15.

[Example 20]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and 2-ethylhexanoic acid (isobutyric acid Of 3,5,5-trimethylhexanoic acid / 2-ethylhexanoic acid ratio) of 61/19/20 (mixed ester 20)]
Instead of 3,5,5-trimethylhexanoic acid, a mixed carboxylic acid of 3,5,5-trimethylhexanoic acid and 2-ethylhexanoic acid is used, and pentaerythritol, dipentaerythritol, isobutyric acid, 3,5,5- The molar ratio of trimethylhexanoic acid and 2-ethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid / 2-ethylhexanoic acid ratio) was set to 1 / 0.18 / A mixed ester 20 was obtained in the same manner as in Example 1 except that the ratio was changed to 3.64 / 1.21 / 1.21.

[Example 21]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and butyric acid (isobutyric acid / 3,5 , 5-Trimethylhexanoic acid / butyric acid ratio) is a 39/18/43 mixed ester (mixed ester 21)]
Instead of 3,5,5-trimethylhexanoic acid, a mixed carboxylic acid of 3,5,5-trimethylhexanoic acid and butyric acid was used, and pentaerythritol, dipentaerythritol, isobutyric acid, 3,5,5-trimethylhexanoic acid and The molar ratio of the amount of butyric acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid / butyric acid ratio) to 1 / 0.18 / 2.43 / 1.21 / 2.43 A mixed ester 21 was obtained in the same manner as in Example 1 except that.

[Example 22]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and pentanoic acid (isobutyric acid / 3, Production of mixed ester (mixed ester 22) having a 5,5-trimethylhexanoic acid / pentanoic acid ratio) of 40/17/43]
A mixed carboxylic acid of 3,5,5-trimethylhexanoic acid and pentanoic acid is used in place of 3,5,5-trimethylhexanoic acid, pentaerythritol, dipentaerythritol, isobutyric acid, 3,5,5-trimethylhexanoic acid And the molar ratio of the amounts of pentanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid / pentanoic acid ratio) of 1 / 0.18 / 2.43 / 1.21 / 2 The mixed ester 22 was obtained in the same manner as in Example 1 except that the ratio was changed to .43.

[Example 23]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and pentanoic acid (isobutyric acid / 3, Production of mixed ester (mixed ester 23) in which 5,5-trimethylhexanoic acid / pentanoic acid ratio) is 38/39/23]
A mixed carboxylic acid of 3,5,5-trimethylhexanoic acid and pentanoic acid is used in place of 3,5,5-trimethylhexanoic acid, pentaerythritol, dipentaerythritol, isobutyric acid, 3,5,5-trimethylhexanoic acid And a molar ratio of the amounts of pentanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid / pentanoic acid ratio) of 1 / 0.18 / 2.43 / 2.43 / 1 The mixed ester 23 was obtained in the same manner as in Example 1 except that it was changed to .21.

[Example 24]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid, 3,5,5-trimethylhexanoic acid and 2-methylbutyric acid (isobutyric acid / Production of mixed ester (mixed ester 24) having a ratio of 3,5,5-trimethylhexanoic acid / 2-methylbutyric acid) of 43/20/37]
Instead of 3,5,5-trimethylhexanoic acid, a mixed carboxylic acid of 3,5,5-trimethylhexanoic acid and 2-methylbutyric acid is used. Pentaerythritol, dipentaerythritol, isobutyric acid, 3,5,5-trimethyl The molar ratio of hexanoic acid and 2-methylbutyric acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid / 2-methylbutyric acid ratio) was 1 / 0.18 / 2.43 The mixed ester 24 was obtained in the same manner as in Example 1 except that the ratio was changed to /1.21/2.43.

[Comparative Example 1]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 60/40, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester A) having a trimethylhexanoic acid ratio) of 12.5 / 87.5]
Isobutyric anhydride is used in place of isobutyric acid, and the molar ratio of pentaerythritol, dipentaerythritol, isobutyric anhydride and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric anhydride) Product / 3,5,5-trimethylhexanoic acid ratio) was changed to 1 / 0.67 / 0.60 / 8.40 in the same manner as in Example 1 to obtain mixed ester A.

[Reference Example 1]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 85/15, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester B) having a trimethylhexanoic acid ratio) of 86/14]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester B was obtained in the same manner as in Example 1 except that 0.18 / 5.30 / 0.79. Since the mixed ester B was a solid at room temperature, it is unsuitable for applications that are used in a wide temperature range such as refrigerator oil.

[Reference Example 2]
[The molar ratio of pentaerythritol and dipentaerythritol (pentaerythritol / dipentaerythritol ratio) is 35/65, and the molar ratio of isobutyric acid and 3,5,5-trimethylhexanoic acid (isobutyric acid / 3,5,5 -Production of mixed ester (mixed ester C) in which trimethylhexanoic acid) is 81/19]
The molar ratio of pentaerythritol, dipentaerythritol, isobutyric acid and 3,5,5-trimethylhexanoic acid used (pentaerythritol / dipentaerythritol / isobutyric acid / 3,5,5-trimethylhexanoic acid ratio) is 1 / A mixed ester C was obtained in the same manner as in Example 1 except that 1.87 / 14.62 / 3.65. Since the mixed ester C was solid at room temperature, it is unsuitable for applications that are used in a wide temperature range, such as refrigerator oil.

(Test Example 1) Measurement of kinematic viscosity Using a Canon-Fenske viscometer, the kinematic viscosities of mixed esters 1 to 24 and mixed ester A at 40 ° C and 100 ° C were measured according to the method of JIS K2283: 2000. The viscosity index was calculated according to the same method. The results are shown in Tables 1-6.

(Test Example 2) Measurement of hydroxyl value The hydroxyl values of mixed esters 1 to 24 and mixed esters A to C were measured according to the method of JIS K-2501. The results are shown in Tables 1-6.

(Test Example 3) Measurement of pour point The pour point of mixed ester 1-24 and mixed ester A was measured according to the method of JIS K2269-1987 using an automatic pour point measuring device RPC-01CML (manufactured by Rouai Co., Ltd.). The results are shown in Tables 1-6.

(Test Example 4) Measurement of two-layer separation temperature The two-layer separation temperatures of mixed esters 1 to 24 and mixed ester A were measured according to the method of JIS K2211: 2009. Each 0.4 g of mixed ester 1-24 and mixed ester A and 3.6 g of difluoromethane refrigerant are sealed in a pressure-resistant glass tube, and the mixture is cooled from 30 ° C. at a rate of 0.5 ° C. per minute. The temperature at which separation or white turbidity occurred was defined as the two-layer separation temperature. The results are shown in Tables 1-6. However, when the mixture is already separated into two layers or clouded at 30 ° C., it is expressed as “separation”.

(Test Example 5) Measurement of friction coefficient Using a shell-type four-ball friction tester (manufactured by Shinko Engineering Co., Ltd.), under conditions of a load of 100 N, a rotation speed of 300 rpm, a temperature of 25 ° C., and a test material [test ball (SUJ-2)] Tests were performed and the friction coefficients of mixed esters 1-24 and mixed ester A were measured. The coefficient of friction was the average of the coefficient of friction for 10 minutes after the familiar operation for 20 minutes under the above conditions. The results are shown in Tables 1-6.

(Test Example 6) Solidification at -20 ° C, confirmation of presence or absence of precipitates (evaluation of low temperature characteristics)
10 g of each of the mixed esters 1 to 24 was put in a glass container and allowed to stand for 10 hours in a thermostat set to −20 ° C. The solidification after standing for 10 hours and the presence or absence of precipitates were confirmed visually. The results are shown below.

＊）室温で固体のため未測定

*) Not measured because it is solid at room temperature

From Tables 1-5, as for mixed ester 1-24, kinematic viscosity in 40 degreeC was 31.2-93.6 mm < ² > / sec, and two-layer separation temperature was -22 degrees C or less. It turns out that mixed ester 1-24 has the outstanding compatibility with a difluoromethane refrigerant | coolant, ensuring the viscosity range required as refrigeration oil.

  From Tables 1 to 5, the mixed esters 1 to 24 had a friction coefficient of 0.10 or less. It turns out that mixed ester 1-24 has the outstanding lubricity.

  From Tables 1-5, as for the mixed esters 1-24, the viscosity index was 69 or more and the pour point was -30 degrees C or less. It can be seen that the mixed esters 1 to 24 have sufficient viscosity-temperature characteristics and sufficient low-temperature fluidity.

  In the evaluation of the low temperature characteristics, the mixed esters 1 to 24 were not solidified, and no precipitate was confirmed. It can be seen that the mixed esters 1 to 24 can be preferably used when stored or used for a long time in a low temperature range.

(Test Example 7) Measurement of solubility of benzotriazole at 5 ° C. Each of the mixed esters 7 to 10, 13, 15 and 4.85 g of the mixed ester A was mixed with 0.15 g of benzotriazole and heated at 60 ° C. Each of the 3 wt% mixed ester solutions of benzotriazole was obtained. Each of the mixed ester solutions was allowed to stand at 5 ° C. for 40 hours, and then the precipitate was visually confirmed.
In the mixed ester solution in which no precipitate was observed, the solubility of benzotriazole at 5 ° C. [the amount of benzotriazole dissolved in 1 g of mixed ester (g)] was set to 0.030 g / g or more. The mixed ester solution in which precipitates were observed was removed by filtration (filter paper; No. 5A, manufactured by Kiriyama Seisakusho), and the obtained filtrate was subjected to high performance liquid chromatography (AGILENT 1200SERIES, column: YMC). Pack Ph A-414 φ6.0 × 300 mm, mobile phase: tetrahydrofuran / 0.1% aqueous phosphoric acid solution = 7/3, column temperature: 40 ° C., flow rate: 0.7 mL / min, detection: UV (220 nm), sample Concentration: 50 g / L, injection amount: 5 μL), and the solubility of benzotriazole at 5 ° C. [dissolution amount of benzotriazole in 1 g of mixed ester (g)] was determined by an absolute calibration curve method. The results are shown in Tables 7 and 8.

(Test Example 8) Measurement of pour point of mixed ester solution 1.35 g of benzotriazole was mixed with 43.65 g of each of mixed esters 7 to 10, 13, 15 and mixed ester A and heated at 60 ° C. Each of the 3 wt% mixed ester solutions of triazole was obtained. Each pour point of the 3 wt% mixed ester solution was measured using an automatic pour point measuring device RPP-01CML (manufactured by Hosei Co., Ltd.) according to the method of JIS K2269-1987. The results are shown in Tables 7 and 8. In Tables 7 and 8, BZT represents benzotriazole.

(Test Example 9) Measurement of wear scar diameter of mixed ester solution In each of 19.80 g of mixed esters 7 to 10, 13 and 15, 0.20 g of benzotriazole was mixed and heated at 60 ° C to obtain 1 of benzotriazole. Each of the weight percent mixed ester solutions was obtained. Each of the obtained 1% by weight mixed ester solution was subjected to a load of 200 N, a rotation speed of 1200 rpm, a time of 30 minutes, a temperature of 75 ° C., a test material [test ball (test ball ( The test was conducted under the conditions of SUJ-2)], and the wear scar diameter after the test was measured. The wear scar diameter was the average value of all three fixed spheres in the vertical and horizontal directions. The results are shown below. The wear resistance of the mixed ester solution indicates that the smaller the wear scar diameter, the better.

  From Tables 7 and 8, it can be seen that the mixed esters 7 to 10, 13 and 15 are excellent in the ability to dissolve benzotriazole when the solubility of benzotriazole at 5 ° C. is 0.030 g / g or more. Further, since the mixed esters 7 to 10, 13 and 15 have a pour point of a 3% by weight mixed ester solution of benzotriazole of −30.0 ° C. or less, excellent low temperature flow when benzotriazole is dissolved. It turns out that it has sex.

  In Test Example 9, the wear scar diameter of the mixed ester solution was 0.51 mm for the mixed ester 7, 0.54 mm for the mixed ester 8, 0.55 mm for the mixed ester 9, and 0. 49 mm, mixed ester 13 was 0.55 mm, and mixed ester 15 was 0.58 mm. It can be seen that the mixed ester of the present invention has sufficient abrasion resistance when benzotriazole is dissolved.

  ADVANTAGE OF THE INVENTION By this invention, the mixed ester used for the refrigerating machine oil etc. which have the outstanding compatibility with a difluoromethane refrigerant | coolant etc. can be provided, ensuring the viscosity range required as a refrigerating machine oil.

Claims (4)

Pentaerythritol and formula (I)

A mixed ester of a mixed polyhydric alcohol composed of dipentaerythritol and a carboxylic acid containing isobutyric acid represented by the formula: wherein the molar ratio of pentaerythritol and dipentaerythritol in the mixed polyhydric alcohol [pentaerythritol / dipenta Erythritol] is in the range of 98/2 to 40/60, and the ratio of isobutyric acid to the carboxylic acid is in the range of 35 to 85 mol%.   The mixed ester according to claim 1, wherein the carboxylic acid contains isobutyric acid and 3,5,5-trimethylhexanoic acid and / or 2-ethylhexanoic acid.   The mixed ester according to claim 1, wherein the carboxylic acid comprises isobutyric acid and 3,5,5-trimethylhexanoic acid. The mixed ester according to claim 1, wherein the carboxylic acid comprises isobutyric acid and 2-ethylhexanoic acid.