JP4843997B2 - Lubricant - Google Patents

Description

  The present invention relates to a lubricating oil, more specifically, a lubricating oil comprising an alicyclic alcohol ester suitable for lubricating oil use, and having an excellent balance of lubricity, low temperature fluidity, metal compatibility and heat resistance, And a method for producing the alicyclic alcohol ester.

  In recent years, there has been a strong demand for improvement in the performance of lubricating oil in devices and machines used in various industrial fields such as automobiles, home appliances, electronic information devices, and industrial machines. That is, with the increase in speed, efficiency, and downsizing of the apparatus, the use conditions of the lubricating oil have become increasingly severe, and a lubricating oil having higher performance than the conventional lubricating oil is required.

  Conventionally, mineral oil that is inexpensive and easily available has been mainly used as the lubricating oil. Mineral oil is a mixture of hydrocarbon oils with various chemical structures, and is roughly divided into paraffinic and naphthenic (cycloparaffinic) based on the main hydrocarbon (such as "Tribology Handbook (Yokendo)") . Paraffinic mineral oil and naphthenic mineral oil differ in viscosity characteristics (for example, viscosity index), lubrication characteristics, low-temperature fluidity, heat resistance and compatibility with additives depending on the degree of purification. When using for the base material of each of these, the use which utilized each characteristic is made | formed properly.

  However, as the required properties such as use under high load conditions and maintenance-free conditions become stricter, it becomes difficult to satisfy the required performance with mineral oil, and synthetic lubricants such as synthetic hydrocarbon oils and organic acid esters with excellent heat resistance Oil is being used. In particular, the organic acid ester has good heat resistance and is excellent in solubility of sludge and tar generated by heat and oxidative deterioration of the lubricating oil. Therefore, it is possible to improve the performance of the lubricating oil by using the organic acid ester alone or in a mixture with mineral oil or synthetic hydrocarbon oil.

  The organic acid esters are roughly classified into aliphatic esters, alicyclic esters, and aromatic esters according to their chemical structures, and are used for applications that make use of their respective characteristics.

  An alicyclic ester is an ester having a cycloalkyl skeleton, and is an ester obtained from the reaction of an alicyclic polyvalent carboxylic acid and a monohydric alcohol (hereinafter referred to as “alicyclic carboxylic acid ester”), alicyclic. An ester obtained from a reaction between a polyhydric alcohol and a monovalent carboxylic acid (hereinafter referred to as “alicyclic alcohol ester”) and the like are disclosed (Patent Documents 1 to 4).

  Among these, US Pat. No. 5,318,711 (Patent Document 1) is exemplified as an ester using an alicyclic polyhydric alcohol. This document discloses an invention in which esters of 1,4-cyclohexanediol and various fatty acids are applied to metalworking oil. However, when the present inventors synthesized an ester by the method disclosed in the specification and evaluated the ester, the performance such as hydrolysis resistance, metal compatibility, and heat resistance is sufficient as a lubricating oil. It turns out that it has no performance.

US Pat. No. 5,318,711 US Pat. No. 3,251,771 U.S. Pat. No. 4,464,277 JP-A-63-139150

  The present invention is a lubricating oil comprising an alicyclic alcohol ester having an excellent balance of lubricity, low temperature fluidity, viscosity characteristics, metal compatibility, hydrolysis stability and heat resistance suitable for various lubricating oil applications, And it aims at providing the manufacturing method of this alicyclic alcohol ester.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have obtained the following knowledge.
(1) In the esterification reaction between an alicyclic dihydric alcohol and an aliphatic and / or alicyclic monocarboxylic acid, the alicyclic dihydric alcohol decomposes during esterification, and the alicyclic monohydric alcohol By-product.
(2) Further, a monoester which is a reaction product of the by-produced alicyclic monohydric alcohol and monocarboxylic acid is by-produced.
(3) Lubricating oils containing the specified amount or more of the monoester of (2) are inferior in heat resistance, flash point, hydrolysis stability and the like.
(4) If an attempt is made to suppress the decomposition of the alicyclic dihydric alcohol during the esterification reaction, the esterification reaction does not proceed sufficiently, and the reaction between 1 mol of the alicyclic dihydric alcohol and 1 mol of the monocarboxylic acid. Increase the amount of monoester by-product obtained.
(5) Lubricating oils containing the specified amount or more of the monoester of (4) above are inferior in heat resistance and hydrolysis stability.
(6) By using a tin-based catalyst as a catalyst during the esterification reaction, the decomposition of the alicyclic dihydric alcohol can be suppressed and the diester production rate can be increased in the esterification reaction.
(7) Furthermore, after the esterification reaction, alkaline washing and distillation and / or adsorption purification are performed, so that the monoester content is low, the flash point is high, excellent hydrolysis stability, heat resistance, and metal compatibility. A lubricating oil having heat resistance and heat resistance should be obtained.
The present invention has been completed based on such knowledge.

  That is, this invention provides the manufacturing method of the following lubricating oil and ester for lubricating oil.

［式中、Ｒ^１、Ｒ^２は、同一又は相異なって、炭素数２〜１８の脂肪族飽和直鎖状モノカルボン酸、炭素数４〜１８の脂肪族飽和分岐鎖状モノカルボン酸、及び炭素数４〜９の脂環族飽和モノカルボン酸からなる群から選ばれる少なくとも一種のモノカルボン酸からカルボキシル基を除いて得られる残基を表す。Ａ^１は、炭素数３〜１２のシクロアルキレン基を表す。］
で表される脂環族アルコールエステルの少なくとも１種を含有する潤滑油であって、該脂環族アルコールエステル中のモノエステル含有量が５重量％以下であり、且つ該脂環族アルコールエステルが、全酸価０．１ｍｇＫＯＨ／ｇ以下、及びヨウ素価２Ｉ_２ｇ／１００ｇ以下である潤滑油。 Item 1 General formula (1)

[Wherein, R ¹ and R ² are the same or different and are each an aliphatic saturated linear monocarboxylic acid having 2 to 18 carbon atoms, an aliphatic saturated branched monocarboxylic acid having 4 to 18 carbon atoms, and It represents a residue obtained by removing a carboxyl group from at least one monocarboxylic acid selected from the group consisting of alicyclic saturated monocarboxylic acids having 4 to 9 carbon atoms. A ¹ represents a cycloalkylene group having 3 to 12 carbon atoms. ]
A lubricating oil containing at least one alicyclic alcohol ester represented by the formula, wherein the monoester content in the alicyclic alcohol ester is 5% by weight or less, and the alicyclic alcohol ester is A lubricating oil having a total acid value of 0.1 mg KOH / g or less and an iodine value of 2I ₂ g / 100 g or less.

Item 2 The lubricating oil according to Item 1, wherein R ¹ and R ² are the same or different residues obtained by removing a carboxyl group from an aliphatic saturated branched monocarboxylic acid having 4 to 9 carbon atoms.

Item 3 A residue obtained by removing a carboxyl group from at least one monocarboxylic acid selected from the group consisting of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid, wherein R ¹ and R ² are the same or different. Item 3. The lubricating oil according to Item 2, which is a base.

Item 4 The lubricating oil according to Item 1, wherein R ¹ and R ² are the same or different residues obtained by removing a carboxyl group from an alicyclic saturated monocarboxylic acid having 4 to 9 carbon atoms.

Item 5 The lubricating oil according to any one of Items 1 to 4, wherein A ¹ is a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, or a 1,4-cyclohexylene group.

Item 6. The lubricating oil according to Item 5, wherein A ¹ is a 1,2-cyclohexylene group.

［式中、Ｒ^１、Ｒ^２は、同一又は相異なって、炭素数２〜１８の脂肪族飽和直鎖状モノカルボン酸、炭素数４〜１８の脂肪族飽和分岐鎖状モノカルボン酸、及び炭素数４〜９の脂環族飽和モノカルボン酸からなる群から選ばれる少なくとも一種のモノカルボン酸からカルボキシル基を除いて得られる残基を表す。Ａ^１は、炭素数３〜１２のシクロアルキレン基を表す。］
で表される脂環族アルコールエステルであり、該脂環族アルコールエステル中のモノエテル含有量が５重量％以下であり、且つ該脂環族アルコールエステルが全酸価０．１ｍｇＫＯＨ／ｇ以下、及びヨウ素価２Ｉ_２ｇ／１００ｇ以下である潤滑油用脂環族アルコールエステルの製造方法であって、
(i)（Ａ）炭素数２〜１８の脂肪族飽和直鎖状モノカルボン酸、炭素数４〜１８の脂肪族飽和分岐鎖状モノカルボン酸、及び脂環族飽和モノカルボン酸からなる群から選ばれる少なくとも一種のモノカルボン酸と、
（Ｂ）一般式（２）

［式中、Ａ^１は、一般式（１）におけると同義である。］
で表される脂環族二価アルコールとを、
（Ａ）成分を、（Ｂ）成分１当量に対して１．０１〜１．５当量用いてエステル化する工程、
(ii)得られたエステル化反応生成物を、アルカリ洗浄する工程、及び
(iii)アルカリ洗浄後のエステル化反応粗物を蒸留する工程及び／又は吸着剤で処理する工程、
を含む脂環族アルコールエステルの製造方法。 Item 7 General formula (1)

[Wherein, R ¹ and R ² are the same or different and are each an aliphatic saturated linear monocarboxylic acid having 2 to 18 carbon atoms, an aliphatic saturated branched monocarboxylic acid having 4 to 18 carbon atoms, and It represents a residue obtained by removing a carboxyl group from at least one monocarboxylic acid selected from the group consisting of alicyclic saturated monocarboxylic acids having 4 to 9 carbon atoms. A ¹ represents a cycloalkylene group having 3 to 12 carbon atoms. ]
The monoether content in the alicyclic alcohol ester is 5% by weight or less, and the alicyclic alcohol ester has a total acid value of 0.1 mgKOH / g or less, and A method for producing an alicyclic alcohol ester for lubricating oil having an iodine value of 2I ₂ g / 100 g or less,
(i) (A) From the group consisting of C2-C18 aliphatic saturated linear monocarboxylic acid, C4-C18 aliphatic saturated branched monocarboxylic acid, and alicyclic saturated monocarboxylic acid At least one monocarboxylic acid selected;
(B) General formula (2)

[Wherein, A ¹ has the same meaning as in general formula (1). ]
An alicyclic dihydric alcohol represented by
A step of esterifying the component (A) using 1.01 to 1.5 equivalents relative to 1 equivalent of the component (B);
(ii) a step of washing the obtained esterification reaction product with an alkali; and
(iii) a step of distilling the esterification reaction crude product after alkali washing and / or a treatment with an adsorbent;
The manufacturing method of alicyclic alcohol ester containing this.

Item 8. The method for producing an alicyclic alcohol ester according to Item 7, wherein the component (B) is a nuclear hydrogenated aromatic dihydroxy compound.

Item 9 The method for producing an alicyclic alcohol ester according to Item 7, wherein the component (B) is 1,2-cyclohexanediol.

  According to the present invention, it is possible to obtain a lubricating oil having an excellent balance of basic required characteristics of lubricity, low temperature fluidity, metal compatibility, viscosity characteristics, heat resistance, and hydrolysis stability. Therefore, it can be used for engine oil, gear oil, automatic transmission oil, continuously variable transmission oil, gas turbine oil, compressor oil, chain oil, hydraulic fluid, bearing lubricating oil, metal working oil, grease, and the like.

［式中、Ｒ^１、Ｒ^２は、同一又は相異なって、炭素数２〜１８の脂肪族飽和直鎖状モノカルボン酸、炭素数４〜１８の脂肪族飽和分岐鎖状モノカルボン酸、及び炭素数４〜９の脂環族飽和モノカルボン酸からなる群から選ばれる少なくとも一種のモノカルボン酸からカルボキシル基を除いて得られる残基を表す。Ａ^１は、炭素数３〜１２のシクロアルキレン基を表す。］
で表される脂環族アルコールエステルであって、該脂環族アルコールエステル中のモノエステル含有量が５重量％以下であり、且つ該脂環族アルコールエステルが、全酸価０．１ｍｇＫＯＨ／ｇ以下、及びヨウ素価２Ｉ_２ｇ／１００ｇ以下の脂環族アルコールエステルである。一般的には、酸成分であるモノカルボン酸と、ジオール成分である脂環族二価アルコールとをエステル化反応に供することによって得られる。 [Aliphatic alcohol ester]
The alicyclic alcohol ester (hereinafter referred to as “the present ester”) according to the present invention is represented by the general formula (1).

[Wherein, R ¹ and R ² are the same or different and are each an aliphatic saturated linear monocarboxylic acid having 2 to 18 carbon atoms, an aliphatic saturated branched monocarboxylic acid having 4 to 18 carbon atoms, and It represents a residue obtained by removing a carboxyl group from at least one monocarboxylic acid selected from the group consisting of alicyclic saturated monocarboxylic acids having 4 to 9 carbon atoms. A ¹ represents a cycloalkylene group having 3 to 12 carbon atoms. ]
In which the monoester content in the alicyclic alcohol ester is 5% by weight or less, and the alicyclic alcohol ester has a total acid value of 0.1 mgKOH / g The following are alicyclic alcohol esters having an iodine value of 2I ₂ g / 100 g or less. In general, it is obtained by subjecting a monocarboxylic acid as an acid component and an alicyclic dihydric alcohol as a diol component to an esterification reaction.

(A) component: monocarboxylic acid (A) As an acid component, C2-C18 aliphatic saturated linear monocarboxylic acid, C4-C18 aliphatic saturated branched monocarboxylic acid, carbon number 4-9 alicyclic saturated monocarboxylic acid is mentioned.

  Specific examples of the aliphatic saturated linear monocarboxylic acid include acetic acid, n-propanoic acid, n-butanoic acid, n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid and n-nonane. Examples include acids, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid, n-tridecanoic acid, n-tetradecanoic acid, n-pentadecanoic acid, n-hexadecanoic acid, n-heptadecanoic acid and n-octadecanoic acid. These can be used for esterification individually or in combination of two or more.

  Specific examples of the aliphatic saturated branched monocarboxylic acid include isobutanoic acid, isopentanoic acid, isohexanoic acid, isoheptanoic acid, isooctanoic acid, 2-ethylhexanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, and isodecane. Examples include acids, isoundecanoic acid, isododecanoic acid, isotridecanoic acid, isotetradecanoic acid, isopentadecanoic acid, isohexadecanoic acid, isoheptadecanoic acid, isooctadecanoic acid and the like. These can be used for esterification individually or in combination of two or more.

  The alicyclic saturated monocarboxylic acid having 4 to 9 carbon atoms may have one or two alkyl branches having 1 to 4 carbon atoms. However, the total number of carbon atoms of the alkyl branch and the cycloalkylene group is 4-9. Such alicyclic saturated monocarboxylic acids include cyclopropanecarboxylic acid, cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cycloheptanecarboxylic acid, cyclooctanecarboxylic acid, methylcyclohexanecarboxylic acid, dimethylcyclohexanecarboxylic acid. Etc. are exemplified. These can be used for esterification individually or in combination of two or more.

  The said (A) component can be used for esterification reaction by 1 type or in combination of 2 or more types.

  Among the above monocarboxylic acid components, aliphatic straight-chain saturated monocarboxylic acids having 4 to 9 carbon atoms are preferable in terms of excellent lubricity, and specifically include n-butanoic acid, n-pentanoic acid, and n-hexane. Acid, n-heptanoic acid, n-octanoic acid and n-nonanoic acid are recommended. Among these, aliphatic straight-chain saturated monocarboxylic acids having 5 to 7 carbon atoms are preferable, and n-heptanoic acid is particularly preferable in terms of excellent balance between lubricity, heat resistance, and low temperature fluidity.

  In terms of excellent metal compatibility, an aliphatic branched saturated monocarboxylic acid having 4 to 9 carbon atoms and an alicyclic monocarboxylic acid having 6 to 9 carbon atoms are preferred. Specifically, isobutanoic acid, isopentanoic acid, isohexane Acid, isoheptanoic acid, isooctanoic acid, 2-ethylhexanoic acid, isononanoic acid, 3,5,5-trimethylhexanoic acid, cyclohexanecarboxylic acid, methylcyclohexanecarboxylic acid, dimethylcyclohexanecarboxylic acid, cycloheptanecarboxylic acid, cyclooctanecarboxylic acid Is recommended. Among them, an aliphatic branched saturated monocarboxylic acid having 6 to 9 carbon atoms is preferable in terms of excellent balance between heat resistance and low temperature fluidity, and in terms of excellent balance between heat resistance, low temperature fluidity, and hydrolysis stability. 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid are particularly preferred.

(B) component: As an alicyclic dihydric alcohol (B) component, C3-C12, Preferably a C6-C10 alicyclic dihydric alcohol is mentioned.

  Specific examples of the alicyclic dihydric alcohol include cyclopropanediol, cyclobutanediol, cyclopentanediol, cyclohexanediol, cycloheptanediol, cyclooctanediol, cyclononanediol, cyclodecanediol, bicyclo [2,2, 1] Heptanediol and bicyclo [4,4,0] decanediol are exemplified.

  The substitution position of the hydroxyl group of the alicyclic dihydric alcohol is not particularly limited, and any positional isomer may be used. For example, in the case of cyclohexanediol, any of 1,2-cyclohexanediol, 1,3-cyclohexanediol and 1,4-cyclohexanediol can be used, and in the case of bicyclo [4,4,0] octenediol Bicyclo [4,4,0] octene-1,2-diol, bicyclo [4,4,0] octene-1,3-diol, bicyclo [4,4,0] octene-1,4-diol, bicyclo [4,4,0] octene-1,5-diol, bicyclo [4,4,0] octene-1,6-diol, bicyclo [4,4,0] octene-1,7-diol, bicyclo [4 , 4,0] octene-1,8-diol, bicyclo [4,4,0] octene-2,3-diol, bicyclo [4,4,0] octene-2,4-diol, bisci Any of b [4,4,0] octene-2,5-diol, bicyclo [4,4,0] octene-2,6-diol and bicyclo [4,4,0] octene-2,7-diol Regioisomers can also be used. Among such positional isomers, a vic-diol in which two hydroxyl groups are bonded to two adjacent carbons is preferable in terms of excellent hydrolysis stability. Examples of the vic-diol include 1,2-cyclohexanediol, bicyclo [4,4,0] octene-1,2-diol, and bicyclo [4,4,0] octene-2,3-diol. .

  Further, these alicyclic dihydric alcohols have a cis isomer and a trans isomer depending on the configuration of the hydroxyl group, and may be any of a cis isomer alone, a trans isomer alone, or a cis isomer / trans isomer mixture.

  As these alicyclic dihydric alcohols, those conventionally known or commercially available can be widely used. However, as a method for producing an alicyclic dihydric alcohol suitable as a raw material for the alicyclic alcohol ester according to the present invention, The method is exemplified.

  The alicyclic dihydric alcohol obtained by nuclear hydrogenation of an aromatic dihydroxy compound is advantageous in terms of easy availability of raw materials and the ability to arbitrarily select the cis / trans isomer ratio, and is preferred for this ester. Recommended as a raw material. In particular, cyclohexanediols obtained by nuclear hydrogenation of hydroquinone, resorcin, and catechol are recommended because of their excellent balance between cost, metal compatibility, and heat resistance.

  A conventionally well-known method can be widely used for nuclear hydrogenation reaction.

  As a hydrogenation catalyst, if it is a catalyst which can hydrogenate an aromatic ring, it will not specifically limit, A conventionally well-known or commercially available hydrogenation catalyst can be used. Examples of the hydrogenation catalyst include catalysts containing a metal such as ruthenium, rhodium, palladium, platinum, iron, cobalt, nickel, copper, and zinc. The form of the hydrogenation catalyst is not particularly limited, and may be any form such as a powder type, a carrier support type, and a sponge metal type.

  The amount of the hydrogenation catalyst is recommended to be in the range of 0.01 to 20% by weight, preferably 0.1 to 10% by weight, based on the catalyst metal content.

  Although the reaction can be carried out without a solvent, it is preferably carried out using a solvent inert to the hydrogenation reaction. Specifically, C1-C4 aliphatic alcohols such as water, methanol, ethanol, n-propanol, iso-propanol, and butanol, alkylenes such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, and ethylene glycol monobutyl ether ( In particular, aliphatic ether compounds such as ethylene or propylene) glycol monoalkyl (1 to 4 carbon atoms) ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, aliphatic cyclic ethers such as tetrahydrofuran, 1,4-dioxane, etc. Among them, aliphatic alcohol alkylene having 1 to 4 carbon atoms (especially ethylene or propylene) is preferred in terms of hydrogenation reaction selectivity and yield. Over monoalkyl (carbon number 1 to 4) ether.

  Examples of the temperature of the hydrogenation reaction include 30 to 200 ° C, preferably 50 to 150 ° C. Even within such a temperature range, the lower the reaction temperature, the easier it is to obtain an alicyclic dihydric alcohol with a higher cis isomer ratio, and the higher the reaction temperature, the easier it is to obtain an alicyclic dihydric alcohol with a higher trans isomer ratio. Therefore, the reaction temperature can be appropriately selected according to the desired isomer ratio.

  The reaction pressure is 0.5-30 MPa, preferably 2-20 MPa as the hydrogen partial pressure.

  The reaction time varies depending on the amount of catalyst, reaction temperature, reaction pressure, and the like, but it is preferable to select the conditions appropriately so that it is usually about 0.5 to 50 hours, preferably about 1 to 20 hours.

  After completion of the hydrogenation reaction, the catalyst is filtered off by a conventionally known method such as filtration or centrifugation, and then the solvent is distilled off if necessary, and extraction, distillation, sublimation, crystallization, chromatography, etc. are commonly used. By using this method, an alicyclic dihydric alcohol can be obtained.

  A vic-diol having two hydroxyl groups bonded to adjacent carbon such as 1,2-cyclohexanediol can also be obtained by epoxidizing the corresponding cycloalkene and hydrating and opening the resulting epoxy group. . For example, after cycloalkene is reacted with an organic peroxide such as hydrogen peroxide, performic acid, peracetic acid, perpropionic acid in the presence of no catalyst or an acid catalyst such as sulfuric acid or phosphoric acid to obtain cycloalkene oxide. In the presence of non-catalytic acid or acid catalyst, hydration ring-opening to obtain vic-cycloalkanediol, air oxidation in the presence of catalyst such as cobalt, manganese, molybdenum, etc., passed through epoxycycloalkene Thereafter, a method of hydration and ring opening in the presence of no catalyst or acid catalyst is exemplified.

  Moreover, it can replace with (B) component which concerns on this invention, and can also use a cycloalkene oxide. That is, the present ester can also be obtained by esterifying the component (A) according to the present invention and cycloalkene oxide. Furthermore, by performing the epoxidation of the cycloalkene in the aliphatic saturated monocarboxylic acid according to the present invention, it can be obtained as a monoester simultaneously with the epoxidation. The monoester can be converted to a diester by subjecting it to a purification treatment as necessary and then subjecting it to an esterification reaction.

  Esters obtained by esterification using cycloalkene oxide as a raw material generally tend to have a high trans isomer ratio, and are recommended as an advantageous method for obtaining the present ester having a high trans isomer ratio.

  Among the alicyclic dihydric alcohols obtained by the above method, those having an iodine value of 1 g / 100 g or less and a peroxide value of 10 meq / g or less are preferable.

［式中、Ｒ^３は、Ｒ^１と同義である。Ａ^３は、炭素数３〜１２のシクロアルキル基又はシクロアルケニル基を表す。］
又は、一般式（４）

［式中、Ｒ^４は、Ｒ^１と同義である。Ａ^４は、Ａ^１と同義である。］
で表され、本エステル中のモノエステルの含有量（即ち、一般式（１）で表される脂環式二価アルコール、一般式（３）及び一般式（４）で表されるモノエステルの総量に対する、一般式（３）及び一般式（４）で表されるモノエステルの量）は、５重量％以下、好ましくは３重量％以下、特に好ましくは１重量％以下含有している。 [Monoester]
The monoester according to the present invention has the general formula (3)

[Wherein R ³ has the same meaning as R ¹ . A ³ represents a cycloalkyl group or cycloalkenyl group having 3 to 12 carbon atoms. ]
Or general formula (4)

[Wherein, R ⁴ has the same meaning as R ¹ . A ⁴ is synonymous with A ¹ . ]
The content of the monoester in this ester (that is, the alicyclic dihydric alcohol represented by the general formula (1), the monoester represented by the general formula (3) and the general formula (4)) The amount of the monoester represented by the general formula (3) and the general formula (4) with respect to the total amount) is 5% by weight or less, preferably 3% by weight or less, and particularly preferably 1% by weight or less.

[Method for producing alicyclic alcohol ester]
The production method of the ester is not particularly limited as long as the specified ester is obtained, but the following production method is exemplified as a preferred production method of the ester.
(i) a step of esterifying the component (A) using 1.01 to 1.5 equivalents relative to 1 equivalent of the component (B);
(ii) a step of washing the obtained esterification reaction product with an alkali; and
(iii) The esterified crude product after the alkali washing is characterized by including a step of distilling and / or a step of treating with an adsorbent.

[Esterification process]
In the esterification, the acid component is, for example, 1.01 to 1.5 equivalent, preferably 1.01 to 1.3 equivalent, more preferably 1 equivalent to 1 equivalent of diol component, as chemical equivalent, to 1 equivalent of diol component. 1.01 to 1.2 equivalents are used. In the case of vic-diol, it is preferable to use 1.1 to 1.3 equivalents in order to obtain a higher diester conversion rate.

  Examples of esterification catalysts include Lewis acids, alkali metals, sulfonic acids, and the like. Specific examples of Lewis acids include aluminum derivatives, tin derivatives, and titanium derivatives. Examples of alkali metals include sodium alkoxide and potassium. Examples include alkoxides, and examples of the sulfonic acids include p-toluenesulfonic acid, methanesulfonic acid, and sulfuric acid. When a catalyst having high acid strength or high esterification activity is used, the by-product amount of the monoester represented by the general formula (3) tends to increase, and the by-product of the general formula (3) is suppressed. When the amount of the catalyst is reduced, the reaction time tends to increase. From such a point of view, tetraalkyl titanate is a catalyst that has a high esterification activity and that can easily produce a high-purity ester of this invention with a small amount of by-products of the monoesters represented by general formulas (3) and (4). , Tin oxide, and tin fatty acid, and tin oxide or tin tin is particularly recommended. The amount used is, for example, about 0.05 to 1.0% by weight with respect to the total weight of the components (A) and (B).

  The esterification reaction is preferably carried out at a reaction temperature of usually 120 to 250 ° C., preferably 140 to 230 ° C., more preferably 180 to 230 ° C. in the presence of an inert gas. The reaction time is usually 3 to 30 hours. If necessary, the produced water may be distilled off azeotropically outside the system using a water entraining agent such as benzene, toluene, xylene, cyclohexane and the like.

[Alkali cleaning process]
The esterification reaction product obtained by the esterification reaction is subjected to alkali washing as it is or after the unreacted acid (water entraining agent if a water entraining agent is used) is distilled off. As a result, the remaining unreacted acid, impurities having a carboxyl group at the terminal, catalyst, and the like are removed, and the present ester excellent in metal compatibility, heat resistance, and the like can be obtained.

  Examples of the cleaning solution used for alkali cleaning include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and aqueous alkali solutions such as alkali metal carbonates such as sodium carbonate, and the concentration thereof is particularly limited. Although not, it is preferably about 0.5 to 20% by weight. The amount of the alkaline aqueous solution used is preferably an amount that is equivalent to or excessive with respect to the total acid value of the reaction product after completion of the reaction. The esterified crude product after alkali washing is preferably washed with water until it becomes neutral.

[Distillation process]
It is preferable to distill off the monoester and the esterification byproduct according to the present invention from the crude esterified product obtained through the alkali washing step by distillation. The distillation conditions are not particularly limited, but include, for example, the monoester in the esterified crude product under conditions of 150 ° C. to 270 ° C./1 Pa to 15000 Pa, preferably 180 ° C. to 230 ° C./1 Pa to 4000 Pa. Distillation is preferably carried out until the amount (ie the weight of the monoester relative to the total weight of the ester, monoester and other impurities) is not more than 5% by weight, preferably not more than 3% by weight, in particular not more than 1% by weight. Although depending on the type of raw material and the amount of impurities, it is usually 0.5 to 10% by weight, preferably 1 to 10% by weight of distillate from the crude esterified product. The amount can be reduced. Furthermore, performing distillation while introducing an inert gas such as nitrogen or argon or water vapor into the gas phase or liquid phase of the distillation apparatus is a preferable method from the viewpoint of shortening the distillation time or suppressing quality deterioration. Illustrated.

[Adsorption treatment process]
The esterified crude product after alkali washing or the esterified crude product obtained through the distillation step can be made into a high-quality ester by further purification with an adsorbent. Examples of the adsorbent include natural or synthetic adsorbents. Specifically, activated carbon, activated alumina, silica gel, silica alumina, activated clay, zeolite, magnesia, calcia, diatomaceous earth, hydrotalcite, synthetic hydrotalcite, ion exchange resin and the like are used. As for the usage-amount, 0.005-5 weight part is illustrated normally with respect to 100 weight part of this ester, Preferably 0.01-3 weight part is recommended.

  It is recommended that two or more of the above adsorbents are used, more preferably three or more. By using two or more kinds of adsorbents, there is a tendency that an ester having more excellent heat resistance is obtained.

  Specific examples of the adsorbent combination include activated carbon and activated alumina combination, activated carbon and silica gel combination, activated carbon and activated clay combination, activated alumina and activated clay combination, activated alumina, activated clay and hydrotalcite combination, A combination of activated carbon, activated clay and activated alumina can be mentioned, and a combination of activated carbon and activated alumina is particularly preferred. As the blending ratio, activated carbon / activated alumina = 80/20 to 20/80, preferably 50/50 to 30/70 is recommended by weight.

  As a purification method using an adsorbent, an adsorbent is added to the ester and stirred at 70 to 100 ° C., preferably 80 to 90 ° C. under normal pressure or reduced pressure for 10 minutes to 2 hours, preferably 30 minutes to 1 hour. The method of doing is mentioned. Alternatively, the adsorption tower may be filled with an adsorbent and the ester passed therethrough. When this adsorption treatment is carried out at normal pressure, it is preferably carried out in an inert gas atmosphere such as nitrogen.

  The purity of the ester thus obtained is usually 95% by weight or more, preferably 97% by weight or more, particularly preferably 99% by weight or more.

[Preferred present ester]

  This ester has a cis isomer and a trans isomer depending on the configuration of two hydroxyl groups of the alicyclic dihydric alcohol, but any isomer of cis isomer, trans isomer alone, or cis / trans mixture may be used. Good. Especially, the mixture of a cis body and a trans body is preferable at the point which is excellent in the balance of low-temperature fluidity | liquidity and hydrolysis stability, and cis / trans = 90/10-10/90 is illustrated as the isomer ratio. Furthermore, cis / trans = 60/40 to 0/100 is preferable from the viewpoint of superior hydrolysis stability. Moreover, cis / trans = 25/75 to 0/100 is preferable from the viewpoint of excellent long-term hydrolysis stability and lubricity.

  The total acid value of the ester is 0.1 mgKOH / g or less, preferably 0.05 mgKOH / g or less. When the total acid value is 0.1 mgKOH / g or less, the heat resistance tends to be improved. The total acid value can also be adjusted by neutralization.

  Examples of the hydroxyl value of the ester include 2 mgKOH / g or less, preferably 1 mgKOH / g or less. When the hydroxyl value is 2 mgKOH / g or less, the hygroscopicity is lowered and the heat resistance tends to be improved. It is desirable that the hydroxyl value is sufficiently reduced in the reaction step.

  The sulfated ash content of the ester is recommended to be 50 ppm or less, preferably 30 ppm or less. When the sulfated ash content is 50 ppm or less, the heat resistance tends to be improved. When the sulfate ash is a component (A) and / or (B) component having a low sulfate ash content (for example, 50 ppm or less), or a metal catalyst is used as the catalyst, It can be adjusted by sufficiently removing itself and the catalyst-derived organometallic compound by neutralization, washing with water and adsorption purification.

The iodine value of this ester is 2I ₂ g / 100 g or less, preferably 1I ₂ g / 100 g or less, particularly preferably 0.5I ₂ g / 100 g or less. When the iodine value is I _{2 2} g / 100 g or less, the heat resistance tends to be improved. The present iodine value ester has (i) (A) component and / or (B) component having a low iodine value (for example, 1 g / 100 g or less, preferably 0.5 I ₂ g / 100 g or less). It can be obtained by (ii) distilling off the monoester according to the production method of the present invention, (iii) reducing (hydrogenating) an alicyclic alcohol ester having an iodine value of 1 or more.

  Among these esters, those having a pour point (JIS K2269) of −20 ° C. or lower are preferable, and those having a pour point of −30 ° C. or lower, more preferably −40 ° C. or lower are preferable.

  Among the present esters, the present ester comprising a linear aliphatic monocarboxylic acid having 4 to 9 carbon atoms as a component (A) and cyclohexanediol as a component (B) as a constituent material is excellent in lubricity. Recommended. Specifically, 1,2-cyclohexanediol di (n-butanoate), 1,2-cyclohexanediol di (n-pentanoate), 1,2-cyclohexanediol di (n-hexanoate), 1,2-cyclohexanediol Di (n-heptanoate), 1,2-cyclohexanediol di (n-octanoate), 1,2-cyclohexanediol di (n-nonanoate), 1,3-cyclohexanediol di (n-butanoate), 1,3- Cyclohexanediol di (n-pentanoate), 1,3-cyclohexanediol di (n-hexanoate), 1,3-cyclohexanediol di (n-heptanoate), 1,3-cyclohexanediol di (n-octanoate), 1, 3-cyclohexanediol di (n Nonanoate), 1,4-cyclohexanediol di (n-butanoate), 1,4-cyclohexanediol di (n-pentanoate), 1,4-cyclohexanediol di (n-hexanoate), 1,4-cyclohexanediol di ( n-heptanoate), 1,4-cyclohexanediol di (n-octanoate), 1,4-cyclohexanediol di (n-nonanoate).

In addition, from the viewpoint of excellent metal compatibility, the present ester is preferably used as the component (A), which is a branched aliphatic monocarboxylic acid having 4 to 9 carbon atoms and cyclohexanediol as the component (B). The Specifically, 1,2-cyclohexanediol diisobutanoate, 1,2-cyclohexanediol diisopentanoate, 1,2-cyclohexanediol diisohexanoate, 1,2-cyclohexanediol diisoheptanoate 1,2-cyclohexanediol diisooctanoate, 1,2-cyclohexanediol di (2-ethylhexanoate), 1,2-cyclohexanediol diisononanoate, 1,2-cyclohexanediol di (3, 5,5-trimethylhexanoate), 1,3-cyclohexanediol diisobutanoate, 1,3-cyclohexanediol diisopentanoate, 1,3-cyclohexanediol diisohexanoate, 1,3-cyclohexanediol Diisoheptanoe , 1,3-cyclohexanediol di isooctanoate, 1,3-cyclohexanediol di (2-ethylhexanoate),
1,3-cyclohexanediol diisononanoate, 1,3-cyclohexanediol di (3,5,5-trimethylhexanoate), 1,4-cyclohexanediol diisobutanoate, 1,4-cyclohexanediol diisopenta Noate, 1,4-cyclohexanediol diisohexanoate, 1,4-cyclohexanediol diisoheptanoate, 1,4-cyclohexanediol diisooctanoate, 1,4-cyclohexanediol di (2-ethyl Hexanoate), 1,4-cyclohexanediol diisononanoate, 1,4-cyclohexanediol di (3,5,5-trimethylhexanoate).

  Among the preferable diesters, a diester of a branched aliphatic saturated monocarboxylic acid having 6 to 9 carbon atoms is preferable as the component (A) because it has an excellent balance between heat resistance and low temperature fluidity. Particularly preferred is a diester of at least one branched saturated monocarboxylic acid selected from 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid from the viewpoint of excellent balance between low-temperature fluidity and hydrolysis stability. Specific examples of such esters include 1,2-cyclohexanediol di (2-ethylhexanoate), 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate), 1,2-cyclohexanediol. And 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid, mixed ester, 1,3-cyclohexanediol di (2-ethylhexanoate), 1,3-cyclohexanediol di (3,5 , 5-trimethylhexanoate), 1,3-cyclohexanediol and 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid mixed ester, 1,4-cyclohexanediol di (2-ethylhexaate) Noate), 1,4-cyclohexanediol di (3,5,5-trimethylhexanoate) , 混基 ester obtained from 1,4-cyclohexanediol and 2-ethylhexanoic acid and 3,5,5-trimethyl hexanoic acid and the like.

[Lubricant]
The lubricating oil of the present invention is a lubricating oil containing the present ester as a lubricating base oil, or a mixture of the present ester and another base oil (hereinafter referred to as “combined base oil”) as a lubricating base oil. It is a lubricating oil, and contains 10 to 100% by weight, preferably 20 to 100% by weight, more preferably 80 to 100% by weight, based on the lubricating base oil. In other words, the combined base oil is contained in an amount of 90% by weight or less, preferably 80% by weight or less, more preferably 20% by weight or less based on the lubricating base oil.

  The above-mentioned combined base oil is obtained by mineral oil (hydrocarbon oil obtained by petroleum refining), poly-α-olefin, polybutene, alkylbenzene, alkylnaphthalene, cycloalkane derivative, Fischer-Tropsch process. Synthetic hydrocarbon oils such as isomerized oils of synthetic hydrocarbons, animal and vegetable oils, organic acid esters other than the present ester, polyalkylene glycols, polyvinyl ethers, polyphenyl ethers, alkylphenyl ethers, silicone oils, and such combined base oils At least one of these can be used in combination as appropriate.

Examples of the mineral oil include solvent refined mineral oil, hydrorefined mineral oil, and wax isomerized oil. Usually, the kinematic viscosity at 100 ° C. is 1.0 to 25 mm ² / s, preferably 2.0 to ²⁰ mm ² / s. Those in the range are used.

Examples of the poly-α-olefin include α-olefins having 2 to 16 carbon atoms (for example, ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, etc. ) And a copolymer having a kinematic viscosity at 100 ° C. of 1.0 to 25 mm ² / s and a viscosity index of 100 or more, particularly a kinematic viscosity at 100 ° C. of 1.5 to 20 mm. Those having a viscosity index of 120 or more at ² / s are preferred.

Examples of polybutene include those obtained by polymerizing isobutylene and those obtained by copolymerizing isobutylene with normal butylene, and generally include a wide range of those having a kinematic viscosity at 100 ° C. of 2.0 to 40 mm ² / s.

  Examples of the alkyl benzene include monoalkyl benzene, dialkyl benzene, trialkyl benzene, and tetraalkyl benzene having a molecular weight of 200 to 450 substituted with a linear or branched alkyl group having 1 to 40 carbon atoms.

  Examples of the alkyl naphthalene include monoalkyl naphthalene and dialkyl naphthalene substituted with a linear or branched alkyl group having 1 to 30 carbon atoms.

  Examples of the cycloalkane derivatives include synthetic naphthenic base oils containing a cyclohexane ring, a cycloheptane ring, a bicycloheptane ring, and a bicyclooctane ring.

  Examples of animal and vegetable oils include beef tallow, lard, palm oil, coconut oil, rapeseed oil, castor oil, sunflower oil and the like.

  Examples of organic acid esters other than the present ester include fatty acid monoesters, aliphatic dibasic acid diesters, polyol esters, and other esters.

  The fatty acid monoester is an ester of an aliphatic linear or branched monocarboxylic acid having 5 to 22 carbon atoms and a linear or branched saturated or unsaturated aliphatic alcohol having 3 to 22 carbon atoms. Is mentioned.

  Examples of the aliphatic dibasic acid diester include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonanedioic acid, decanedioic acid and the like Or the full ester of the anhydride and C3-C22 linear or branched saturated or unsaturated aliphatic alcohol is mentioned.

  Examples of polyol esters include neopentyl polyols such as neopentyl glycol, trimethylol propane, pentaerythritol, ditrimethylol propane, dipentaerythritol, and linear and / or branched saturated or unsaturated C 3-22. Examples include full esters with fatty acids.

  Examples of other esters include polymerized fatty acids such as dimer acid and hydrogenated dimer acid, or hydroxy fatty acids such as condensed castor oil fatty acid and hydrogenated condensed castor oil fatty acid, and linear or branched chains having 3 to 22 carbon atoms. And esters with saturated or unsaturated fatty alcohols.

Examples of the polyalkylene glycol include a ring-opening polymer of alcohol and a linear or branched alkylene oxide having 2 to 4 carbon atoms. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide, and a polymer using one of these or a copolymer using two or more kinds of mixtures can be used. A compound in which one or both hydroxyl groups are etherified or esterified can also be used. The kinematic viscosity of the polymer is usually 5.0 to 1000 mm ² / s (40 ° C.), preferably 5.0 to 500 mm ² / s (40 ° C.).

Polyvinyl ether is a compound obtained by polymerization of vinyl ether monomers, and monomers include methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, sec-butyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether. N-hexyl vinyl ether, 2-methoxyethyl vinyl ether, 2-ethoxyethyl vinyl ether, and the like. The kinematic viscosity of the polymer is usually 5.0 to 1000 mm ² / s (40 ° C.), preferably 5.0 to 500 mm ² / s (40 ° C.).

  Examples of polyphenyl ether include compounds having a structure in which meta positions of two or more aromatic rings are connected by an ether bond or a thioether bond. Specifically, bis (m-phenoxyphenyl) ether, m-bis ( m-phenoxyphenoxy) benzene, and thioethers (commonly referred to as C-ether) in which one or more of these oxygens are substituted with sulfur.

  Examples of the alkyl phenyl ether include compounds in which polyphenyl ether is substituted with a linear or branched alkyl group having 6 to 18 carbon atoms, and alkyl diphenyl ether substituted with one or more alkyl groups is particularly preferable.

  Examples of the silicone oil include dimethyl silicone and methylphenyl silicone, and modified silicones such as long-chain alkyl silicone and fluorosilicone.

  Among these combined base oils, synthetic hydrocarbon oils and organic acid esters are preferable in terms of excellent heat resistance and lubricity, and in particular, poly-α-olefins, cycloalkane derivatives, aliphatic dibasic acid diesters and polyol esters. preferable.

  In order to improve the performance of the lubricating oil of the present invention, known antioxidants, metal detergents, ashless dispersants, oiliness agents, antiwear agents, extreme pressure agents, metal deactivators, rust inhibitors, One or more additives such as a viscosity index improver, a pour point depressant, and an antifoaming agent can be appropriately blended. Although these compounding quantities are not specifically limited as long as there exists a predetermined effect, The specific example is shown below.

  Antioxidants include 2,6-di-tert-butyl-p-cresol, 2-tert-butyl-4-hydroxyanisole, 2,5-di-tert-butylhydroquinone, 4-hydroxymethyl-2,6 -Phenols such as di-tert-butylphenol, 4,4'-methylenebis-2,6-di-tert-butylphenol, 2,2'-methylenebis-4-methyl-6-tert-butylphenol, N-phenyl-α Examples thereof include amine compounds such as naphthylamine and p, p′-dioctyldiphenylamine, and sulfur compounds such as p, p′-dinonyldiphenylamine, mixed dialkyldiphenylamine and phenothiazine. These antioxidants can be used alone or in combination. When used, these antioxidants are usually added in an amount of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the lubricating base oil.

  Metal detergents include Ca-petroleum sulfonate, overbased Ca-petroleum sulfonate, Ca-alkyl benzene sulfonate, overbased Ca-alkyl benzene sulfonate, Ba-alkyl benzene sulfonate, over-based Ba-alkyl benzene sulfonate. Phonate, Mg-alkylbenzenesulfonate, overbased Mg-alkylbenzenesulfonate, Na-alkylbenzenesulfonate, overbased Na-alkylbenzenesulfonate, Ca-alkylnaphthalenesulfonate, overbased Ca- Metal sulfonates such as alkyl naphthalene sulfonates, Ca-phenates, overbased Ca-phenates, Ba-phenates, overbased Ba-phenates and other metal phenates, Ca-salicylate, overbased C Metal salicylates such as salicylates, Ca-phosphonates, overbased Ca-phosphonates, Ba-phosphonates, overbased Ba-phosphonates and other metal phosphonates, overbased Ca-carboxylates Etc. are exemplified. These metal detergents can be used alone or in combination. When these metal detergents are used, it is usually desirable to add 1 to 10 parts by weight, preferably 2 to 7 parts by weight, per 100 parts by weight of the lubricating base oil.

  Examples of the ashless dispersant include polyalkenyl succinimide, polyalkenyl succinamide, polyalkenyl benzylamine, polyalkenyl succinate and the like. These ashless dispersants can be used alone or in combination. When used, these ashless dispersants are usually added in an amount of 1 to 10 parts by weight, preferably 2 to 7 parts by weight, based on 100 parts by weight of the lubricating base oil.

  Examples of oily agents include aliphatic saturated and unsaturated monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, lauryl alcohol, Aliphatic saturated and unsaturated monoalcohols such as oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine and oleylamine, aliphatic saturated and unsaturated monocarboxylic amides such as lauric acid amide, oleic acid amide, batyl alcohol, Glycerol ethers such as chimyl alcohol and ceralkyl alcohol, alkyl or alkenyl polyglyceryl ethers such as lauryl polyglyceryl ether and oleyl polyglyceryl ether, di (2-ethylhexyl) monoethanolamine , Poly (alkylene oxide) alkyl or alkenyl amines such as diisotridecyl monoethanolamine adduct and the like. These oily agents may be used alone or in combination. When these oil-based agents are used, they are usually added in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the lubricating base oil.

  Antiwear / extreme pressure agents include tricresyl phosphate, cresyl diphenyl phosphate, alkylphenyl phosphates, phosphate esters such as tributyl phosphate, dibutyl phosphate, tributyl phosphate, dibutyl phosphate, triisopropyl phosphate, etc. Phosphorous esters of these and phosphorus salts such as amine salts thereof, sulfurized fatty acids such as sulfurized fats and oils, sulfurized oleic acid, sulfurous systems such as dibenzyl disulfide, sulfurized olefin and dialkyl disulfide, Zn-dialkyldithiophosphate, Zn- Examples thereof include organometallic compounds such as dialkyldithiophosphate, Mo-dialkyldithiophosphate, and Mo-dialkyldithiocarbamate. These antiwear agents can be used alone or in combination. These antiwear / extreme pressure agents are usually added in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the lubricating base oil.

  Examples of the metal deactivator include benzotriazole-based, thiadiazole-based, and gallic acid ester-based compounds. These metal deactivators can be used alone or in combination. When used, these metal deactivators are usually added in an amount of 0.01 to 0.4 parts by weight, preferably 0.01 to 0.2 parts by weight, based on 100 parts by weight of the lubricating base oil. .

  Antirust agents include alkyl or alkenyl succinic acid derivatives such as dodecenyl succinic acid half ester, octadecenyl succinic anhydride, dodecenyl succinic acid amide, sorbitan monooleate, glycerin monooleate, pentaerythritol monooleate Partial alcohol ester, Ca-petroleum sulfonate, Ca-alkyl benzene sulfonate, Ba-alkyl benzene sulfonate, Mg-alkyl benzene sulfonate, Na-alkyl benzene sulfonate, Zn-alkyl benzene sulfonate, Ca-alkyl naphthalene sulphate Examples thereof include metal sulfonates such as phonates, amines such as rosinamine and N-oleylsarcosine, dialkyl phosphiteamine salts, and the like. These rust inhibitors can be used alone or in combination. When used, these rust inhibitors are usually added in an amount of 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the lubricating base oil.

  Examples of the viscosity index improver include olefin copolymers such as polyalkyl methacrylate, polyalkyl styrene, polybutene, ethylene-propylene copolymer, styrene-diene copolymer, and styrene-maleic anhydride ester copolymer. . These viscosity index improvers can be used alone or in combination. When used, these viscosity index improvers are usually added in an amount of 0.1 to 15 parts by weight, preferably 0.5 to 7 parts by weight, based on 100 parts by weight of the lubricating base oil.

  Examples of the pour point depressant include a condensate of chlorinated paraffin and alkylnaphthalene, a condensate of chlorinated paraffin and phenol, polyalkyl methacrylate, polyalkylstyrene, polybutene and the like as the viscosity index improvers described above. These pour point depressants can be used alone or in combination. When using these pour point improvers, it is usually desirable to add 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, per 100 parts by weight of the lubricating base oil.

  As the antifoaming agent, liquid silicone is suitable. When the antifoaming agent is used, the amount added is usually 0.0005 to 0.01 parts by weight with respect to 100 parts by weight of the lubricating base oil.

  The lubricating oil according to the present invention has a high flash point, excellent heat resistance, hydrolysis resistance, low temperature fluidity, and metal compatibility compared to a lubricating oil containing a conventionally known alicyclic dihydric alcohol ester. Excellent balance.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, various properties of esters, physical properties and chemical properties of lubricating oil were measured by the following methods.

(A) Ester composition (diester content, monoester content, cis / trans isomer ratio)
Measured by gas chromatography.

(B) Total acid value It measured based on JISK2501.

(D) Iodine value It measured based on the standard oil-fat analysis method 2.3.4.1-1996.

(E) Kinematic viscosity Kinematic viscosity at 40 ° C and 100 ° C was measured according to JIS K2283.

(F) Viscosity index Calculated according to JIS K2283.

(G) Low temperature fluidity test The pour point was measured according to JIS K2269.

(H) Lubricity test In accordance with JPI-5S-32-90, using a high-speed four-ball wear tester (manufactured by Shinko Machine), the test was performed under conditions of a rotation speed of 700 rpm, a load of 5 kg, and a time of 60 minutes. The scar diameter was measured. It was judged that the smaller the wear scar formed, the better the lubricity.

(I) Hydrolysis stability test Into a glass test tube having an inner diameter of 6.6 mm and a height of 30 cm, 2.0 g of the ester of each example having water content adjusted to about 1000 ppm is weighed. The test tube was sealed while deaerated with an aspirator, placed in an oven, and heated at 175 ° C. for 20 hours. Thereafter, the ester was taken out and the total acid value was measured (hydrolysis stability-1).
Moreover, the total acid value of ester after heating at 175 degreeC for 40 hours was measured, and it was set as the long-term hydrolysis stability test (hydrolysis stability -2).
It was judged that the smaller the increase in the total acid value, the better the hydrolysis stability.

(J) Heat resistance test (volatilization amount)
Lubricating oil was prepared by dissolving 0.5% by weight of 2,6-di-tert-butyl-p-cresol for each ester of Examples and Comparative Examples. Next, 2 g of the additive oil was placed in a 50 mL beaker having an inner diameter of 53 mm and a height of 56 mm, and the cap was covered with a 200 mL beaker, and then heated in an oven at 150 ° C. for 24 hours. After the test, the volatilization amount was calculated from the following formula.
Volatilization amount (% by weight) = (W ₀ −W ₁ ) / W ₀ × 100
However, W ₀ represents the weight of the lubricating oil before heating, and W ₁ represents the weight of the lubricating oil after heating.
Further, the acid value of the lubricating oil after the heat resistance test (volatilization amount) was measured, and the difference from the acid value of the lubricating oil before the test was defined as ΔTAN.
The smaller the volatilization amount and ΔTAN, the better the heat resistance.

(K) Metal compatibility test About 50 mL of the ester of Example or Comparative Example was placed in a 50 mL stoppered test tube, a metal piece (iron, copper, lead) was added, and heated in an oven at 90 ° C. for 14 days. After the test, the total acid number of the filtered ester is measured. The smaller the increase in the total acid value, the better the compatibility with the metal. The following test pieces were used.
Iron: Wire (length 40 mm, diameter 1.6 mm), used after polishing the surface with abrasive paper (No. 600).
Copper: Wire (length 40 mm, diameter 1.6 mm), used after polishing the surface with abrasive paper (No. 600).
Lead: Bulk lead (approx. 1g, Nacalai Tesque product)

[Example 1]
(Nuclear hydrogenation process)
Into a 3L autoclave equipped with an electromagnetic induction stirrer, 500 g (4.5 mol) of hydroquinone, 500 g of water and 1.5 g of a developed sponge nickel catalyst (NDT-90, manufactured by Kawaken Fine Chemical Co., Ltd.) are placed, and the inside of the autoclave is replaced with hydrogen. Then, a hydrogenation reaction was performed at a gauge pressure of 3.0 MPa and 140 ° C. The reaction was performed while replenishing the consumed hydrogen, and continued until no pressure decrease was observed. After completion of the reaction, the reaction mixture was cooled and the catalyst was removed by filtration under reduced pressure. The filtrate was heated to 140 ° C. under reduced pressure to distill off water, then cooled and solidified, and 500 g of a white solid of 1,4-cyclohexanediol (hereinafter abbreviated as “1,4-CHD”). (Yield 95%). The purity of 1,4-CHD obtained was 98% by weight, and the isomer ratio was cis / trans = 47/53).

(Esterification process)
Into a 1 liter four-necked flask equipped with a stirrer, a thermometer and a water fraction receiver with a cooling tube, 174 g (1.5 mol) of 1,4-CHD obtained in the nuclear hydrogenation step, 3, 5 , 5-trimethylhexanoic acid 568.8 g (3.6 mol: 1.2 equivalents to component (B)), xylene [5% by weight based on the total weight of components (A) and (B)] and As a catalyst, p-toluenesulfonic acid [1.0% by weight based on the total weight of the components (A) and (B)] was charged, and the temperature was gradually raised to 140 ° C. in a nitrogen atmosphere. The esterification reaction was carried out for about 5 hours under reduced pressure while removing the produced water distilled off with a water fraction receiver with the theoretically produced water amount (54 g) as a guide. After completion of the reaction, excess acid and xylene were removed by distillation.

(Alkali cleaning process)
Next, the total acid value of the esterification reaction product was neutralized with an excess of aqueous caustic soda solution, and then washed with water until neutrality to obtain 576 g of a crude esterification reaction product. The diester content in this esterification reaction crude product was 96.8% by weight.

(Distillation process)
Next, the obtained esterification reaction crude product was heated to 180 ° C. under a condition of 667 Pa to distill off monoesters and esterification by-products.

(Adsorption treatment process)
After completion of the distillation step, activated alumina and activated carbon (0.1% by weight each based on the theoretical yield of the ester) were added at 80 ° C. and stirred for 1 hour for treatment. After the treatment, filtration was performed to obtain 500 g of 1,4-cyclohexanediol di (3,5,5-trimethylhexanoate). The composition, acid value, and iodine value of the resulting “ester A” are shown in Table 1.

[Example 2]
(Hydrogenation process)
A hydrogenation reaction is performed in the same manner as in the nuclear hydrogenation step of Example 1 except that resorcin is used instead of hydroquinone, and is abbreviated as 1,3-cyclohexanediol (hereinafter, “1,3-CHD”). ) 485 g (yield 92%). The purity of the obtained 1,3-CHD was 94% by weight, and the isomer ratio was cis / trans = 50/50).

(Production of this ester)
In the same manner as in Example 1, except that 174 g (1.5 mol) of 1,3-CHD obtained in the above hydrogenation step was used instead of 1,4-CHD, and the reaction time was about 22 hours. Then, esterification, alkali washing, distillation, and adsorption treatment were performed to obtain 511 g of 1,3-cyclohexanediol di (3,5,5-trimethylhexanoate). Table 1 shows the composition, acid value, and iodine value of the resulting “ester B”.

[Example 3]
(Hydrogenation process)
Hydrogenation of Example 1 except that catechol was used instead of hydroquinone, isopropanol 335 g, developed sponge nickel catalyst (NDT-90, manufactured by Kawaken Fine Chemical Co., Ltd.) 33 g, gauge pressure 5.0 MPa, reaction temperature 130 ° C. The reaction was performed in the same manner as in the step, and isopropanol was distilled off to obtain 501 g (yield 95%) of 1,2-cyclohexanediol (hereinafter abbreviated as “1,2-CHD”). The purity of 1,2-CHD obtained was 98% (containing 1.4% by weight of cyclohexanol), and the isomer ratio was cis / trans = 57/43.

(Production of this ester)
Instead of 1,4-CHD, 174 g (1.5 mol) of 1,2-CHD obtained in the above hydrogenation step was used, the reaction temperature was 180 ° C., the reaction time was about 10 hours, and the catalyst was tetraisopropyl titanate [( Esterification, alkali washing, distillation, and adsorption treatment were carried out in the same manner as in Example 1 except that 0.5 wt% with respect to the total weight of component A) and component (B)]. 508 g of cyclohexanediol di (3,5,5-trimethylhexanoate) was obtained. Table 1 shows the composition, acid value, and iodine value of the obtained “ester C”.

[Example 4]
(Synthesis example of cyclohexanediol)
A 3-liter four-necked flask equipped with a stirrer, a thermometer and a water fraction receiver with a condenser was charged with 392 g (4 mol) of cyclohexene oxide, 1 kg of ion-exchanged water and 1 g of phosphoric acid, and the temperature was raised to 80 ° C. . 232 g (4.1 mol) of 60% aqueous hydrogen peroxide was added dropwise over 1 hour. After completion of the dropwise addition, the reaction was further aged for 1 hour, and 800 ml of water was distilled off under reduced pressure. After cooling, 500 ml of acetone was added to obtain 315 g of 1,2-CHD (yield 65%) as white crystals. The purity of the obtained 1,2-CHD was 99%, and the isomer ratio was cis / trans = 0/100.

(Production of this ester)
Instead of 1,4-CHD, 174 g (1.5 mol) of 1,2-CHD obtained in the above synthesis example was used, the reaction temperature was 180 ° C., the reaction time was about 10 hours, and the catalyst was tetraisopropyl titanate [( Except for 0.5% by weight based on the total weight of the component (A) and the component (B), esterification, alkali washing, distillation, and adsorption treatment were performed in the same manner as in Example 1, and 1,2 -514 g of cyclohexanediol di (3,5,5-trimethylhexanoate) was obtained. The composition, acid value, and iodine value of the resulting “ester D” are shown in Table 1.

[Example 5]
Instead of 1,4-CHD, 174 g (1.5 mol) of 1,2-CHD obtained by the same method as in the hydrogenation step of Example 3 and 483.5 g of 3,5,5-trimethylhexanoic acid ( 3.06 mol: 1.02 equivalent), the reaction temperature was 225 ° C., the reaction time was about 8 hours, and the catalyst was tin oxide [0.2% by weight based on the total weight of the components (A) and (B). And by using the same method as in Example 1 except that xylene [5% by weight based on the total weight of the components (A) and (B)] was used as a water entraining agent. Then, adsorption treatment was performed to obtain 498 g of 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate). The composition, acid value, and iodine value of the obtained “Ester E” are shown in Table 1.

[Example 6]
Instead of 1,4-CHD, 174 g (1.5 mol) of the reagent 1,2-CHD (cis / trans = 77/23) was used, the reaction temperature was 230 ° C., the reaction time was about 8 hours, Except for tin oxide [0.2% by weight based on the total weight of component (A) and component (B)], esterification, alkali washing, distillation and adsorption treatment were performed in the same manner as in Example 1. 529 g of 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate) were obtained. The composition, acid value and iodine value of the obtained “ester F” are shown in Table 1.

[Example 7]
Instead of 1,4-CHD, 174 g (1.5 mol) of the reagent 1,2-CHD (cis / trans = 77/23) was used, the reaction temperature was 230 ° C., the reaction time was about 8 hours, Except for tin oxide [0.2% by weight based on the total weight of component (A) and component (B)], esterification and alkali washing were performed in the same manner as in Example 1, and the diester content was A crude esterification reaction product of 98.1% by weight was obtained. Subsequently, purification with activated carbon and activated alumina was performed in the same manner as in Example 1, and after filtration, 529 g of 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate) was obtained. The composition, acid value, and iodine value of the obtained “ester G” are shown in Table 1.

[Example 8]
Instead of 1,4-CHD, 174 g (1.5 mol) of the reagent 1,2-CHD (cis / trans = 77/23) and 483.5 g (3.3) of 3,5,5-trimethylhexanoic acid Mol: 1.1 equivalents), the reaction temperature was 230 ° C., the reaction time was about 10 hours, and the catalyst was tin oxide [0.2% by weight based on the total weight of the components (A) and (B)]. Except for the above, esterification, alkali washing, distillation, and adsorption treatment were performed in the same manner as in Example 1 to obtain 529 g of 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate). The composition, acid value, and iodine value of the obtained “ester H” are shown in Table 1.

[Example 9]
(Hydrogenation process)
The hydrogenation step of Example 1 except that catechol was used in place of hydroquinone, propylene glycol monomethyl ether 500 g, stabilized nickel catalyst (SN-110, Sakai Chemical Industry Co., Ltd.) 15 g, and gauge pressure 3.0 MPa. In the same manner, propylene glycol monomethyl ether was distilled off to obtain 502 g of 1,2-CHD (yield 95%). The purity of the obtained 1,2-CHD was 98% (containing 2% by weight of cyclohexanol), and the isomer ratio was cis / trans = 35/65.

(Production of this ester)
Instead of 1,4-CHD, 174 g (1.5 mol) of 1,2-CHD obtained in the above hydrogenation step was used, the reaction temperature was 230 ° C., the reaction time was about 8 hours, and the catalyst was tin oxide [(A 1), 2-cyclohexane, esterification, alkali washing, distillation and adsorption treatment were carried out in the same manner as in Example 1 except that the content was 0.2 wt% with respect to the total weight of component (B) and component (B). 508 g of diol di (3,5,5-trimethylhexanoate) was obtained. The composition, acid value and iodine value of the obtained “ester I” are shown in Table 1.

[Example 10]
Instead of 1,4-CHD, 174 g (1.5 mol) of the reagent 1,2-CHD (cis / trans = 77/23) was used, the reaction temperature was 140 ° C., the reaction time was about 6 hours, Esterification, alkali washing, distillation, and adsorption treatment were performed in the same manner as in Example 1 except that xylene [5% by weight based on the total weight of the components (A) and (B)] was used as the water entraining agent. As a result, 498 g of 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate) was obtained. The composition, acid value, and iodine value of the resulting “ester J” are shown in Table 1.

[Example 11]
Instead of 3,5,5-trimethylhexanoic acid, 518.4 g of 2-ethylhexanoic acid [3.6 mol: 1.2 equivalents to component (B)] was used, and instead of 1,4-cyclohexanediol. , 174 g (1.5 mol) of 1,2-CHD (cis / trans = 77/23) of the reagent was used, the reaction temperature was 230 ° C., the reaction time was about 13 hours, and the catalyst was tin oxide [component (A) and (B) Esterification, alkali washing, distillation, and adsorption treatment were performed in the same manner as in Example 1 except that the content was changed to 0.2% by weight based on the total amount of the component, and 1,2-cyclohexanediol di ( 498 g of 2-ethylhexanoate) was obtained. Table 1 shows the composition, acid value, and iodine value of the obtained “ester K”.

[Example 12]
Instead of 3,5,5-trimethylhexanoic acid, 429 g of n-heptanoic acid [3.3 mol: 1.1 equivalents to component (B)] was used, and instead of 1,4-cyclohexanediol, Using 174 g (1.5 mol) of 1,2-CHD (cis / trans = 77/23), the reaction temperature was 180 ° C., the reaction time was about 10 hours, the excess ratio of the raw acid was 10 mol%, Except for stannous octoate (0.3% by weight based on the total amount of component (A) and component (B)), esterification, alkali washing, distillation and adsorption treatment were performed in the same manner as in Example 1. 444 g of 1,2-cyclohexanediol di (n-heptanoate) were obtained. Table 1 shows the composition, acid value, and iodine value of the obtained “ester L”.

[Example 13]
Instead of 3,5,5-trimethylhexanoic acid, 138.2 g (1.08 mol) of cyclohexanecarboxylic acid and 362.9 g (2.52 mol) of 2-ethylhexanoic acid [total 3.6 mol: component (B) 1.2 equivalents], and instead of 1,4-cyclohexanediol, 174 g (1.5 mol) of the reagent 1,2-CHD (cis / trans = 77/23) was used, and the reaction temperature was 230 ° C., the reaction time was about 15 hours, the excess ratio of the raw acid was 20 mol%, and the catalyst was tin oxide [0.3 wt% based on the total amount of the components (A) and (B)], In the same manner as in Example 1, esterification, alkali washing, distillation, and adsorption treatment were performed to obtain 458 g of 1,2-cyclohexanediol dicyclohexanecarboxylate. The composition, acid value, and iodine value of the obtained “ester M” are shown in Table 1.

[Comparative Example 1]
Instead of 1,4-CHD, 174 g (1.5 mol) of 1,3-CHD obtained by the same method as in the hydrogenation step of Example 2 was used, the reaction temperature was 140 ° C., and the reaction time was about 22 hours. The esterification reaction was carried out by the same method as in Example 1 except that. After completion of the reaction, excess acid and xylene were removed by distillation. Next, the mixture was neutralized with an aqueous caustic soda solution in excess of the total acid value after completion of the reaction, and washed with water until neutrality. Filtration was performed without distillation and adsorption treatment to obtain 574 g of 1,3-cyclohexanediol di (3,5,5-trimethylhexanoate). The composition, acid value and iodine value of the obtained “ester N” are shown in Table 1.

[Comparative Example 2]
N-Heptanoic acid 429 g (3.3 mol) was used instead of 3,5,5-trimethylhexanoic acid, and instead of 1,4-CHD, the hydrogenation step of Example 3 was used. Using 174 g (1.5 mol) of 1,2-CHD and 521.4 g of 3,5,5-trimethylhexanoic acid [3.3 mol: 1.1 equivalent to the component (B)], the reaction temperature was 180. Esterification was carried out in the same manner as in Example 1 except that the reaction time was about 10 hours and the catalyst was tin octylate [0.3% by weight based on the total weight of the components (A) and (B)]. Reaction was performed. After completion of the reaction, excess acid and xylene were removed by distillation. Next, the mixture was neutralized with an aqueous caustic soda solution in excess of the total acid value after completion of the reaction, and washed with water until neutrality. Filtration was performed without distillation and adsorption treatment to obtain 481 g of 1,2-cyclohexanediol di (n-heptanoate). The composition, acid value, and iodine value of the obtained “ester Q” are shown in Table 1.

[Comparative Example 3]
Instead of 1,4-CHD, 174 g (1.5 mol) of 1,2-CHD obtained by the same method as in the hydrogenation step of Example 3 was used, the reaction temperature was 180 ° C., and the reaction time was about 10 hours. The esterification reaction was carried out in the same manner as in Example 1 except that the catalyst was tetraisopropyl titanate [0.5% by weight based on the total amount of the components (A) and (B)]. After completion of the reaction, excess acid and xylene were removed by distillation. Next, the mixture was neutralized with an aqueous caustic soda solution in excess of the total acid value after completion of the reaction, and washed with water until neutrality. Filtration was carried out without distillation and adsorption treatment to obtain 570 g of 1,2-cyclohexanediol di (3,5,5-trimethylhexanoate). The composition, acid value, and iodine value of the resulting “ester R” are shown in Table 1.

Examples 14-26
Results of kinematic viscosity, viscosity index, flash point, low temperature fluidity test, lubricity test, hydrolysis stability test, metal compatibility test, and heat resistance test of the lubricating oils comprising the esters obtained in Examples 1-13 Are shown in Table 2.

Comparative Examples 4-6
Table 2 shows the results of the kinetic viscosity, viscosity index, flash point, low temperature fluidity test, lubricity test, hydrolysis stability test, metal compatibility test, and heat resistance test of the esters obtained in Comparative Examples 1 to 3. Indicated.

  As is apparent from Table 1, the production method of the present invention can provide an alicyclic alcohol ester having a low monoester content, acid value, hydroxyl value and iodine value. Further, as is apparent from Table 2, the lubricating oil containing the alicyclic alcohol ester of the present invention has an excellent balance of low viscosity, lubricity, low temperature fluidity, metal compatibility, heat resistance and the like. ing. In particular, diesters using at least one selected from aliphatic branched saturated monocarboxylic acids and alicyclic monocarboxylic acids are excellent in hydrolysis stability, especially diesters using 1,2-substituted diols. Show good hydrolytic stability. In addition, it is clear that the lubricating oils that do not use the present ester shown in Comparative Examples 4 to 6 have a low flash point, poor heat resistance, and do not have sufficient performance as a lubricating oil.

Since the lubricating oil of the present invention is excellent in the balance of the basic required characteristics of the lubricating oil, automobile engine oil such as gasoline engine oil, diesel engine oil, gas engine oil, gear oil, automatic transmission oil, continuously variable transmission oil, etc. In addition to drive system lubricating oil and bearing lubricating oil, it can be suitably used for jet engine oil, hydraulic fluid, compressor oil, chain oil, gas turbine oil, metalworking oil, grease base oil, and the like.


Patent applicant New Nippon Rika Co., Ltd.

Claims (5)

General formula (1)

[Wherein, R ¹ and R ² are the same or different and are each an aliphatic saturated linear monocarboxylic acid having 2 to 18 carbon atoms, an aliphatic saturated branched monocarboxylic acid having 4 to 18 carbon atoms, and It represents a residue obtained by removing a carboxyl group from at least one monocarboxylic acid selected from the group consisting of alicyclic saturated monocarboxylic acids having 4 to 9 carbon atoms. A ¹ represents a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, or a 1,4-cyclohexylene group . ]
A lubricating oil containing at least one alicyclic alcohol ester represented by the formula: wherein the content of monoester in the alicyclic alcohol ester is 5% by weight or less, and the alicyclic alcohol ester is A lubricating oil having a total acid value of 0.1 mg KOH / g or less and an iodine value of 2I ₂ g / 100 g or less (excluding lubricating oil for power transmission) . The lubricating oil according to claim ^1, wherein R ¹ and R ² are the same or different residues obtained by removing a carboxyl group from an aliphatic saturated branched monocarboxylic acid having 4 to 9 carbon atoms. R ¹ and R ² are the same or different residues obtained by removing a carboxyl group from at least one monocarboxylic acid selected from the group consisting of 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid. The lubricating oil according to claim 2. The lubricating oil according to claim ^1, wherein R ¹ and R ² are the same or different residues obtained by removing a carboxyl group from an alicyclic saturated monocarboxylic acid having 4 to 9 carbon atoms. A ¹ The lubricating oil according to claim 1 is a 1,2-cyclohexylene group.