JP5334421B2 - Ester base oil and lubricating oil for lubricating oil - Google Patents

Description

  The present invention relates to ester base oils and lubricating oils for lubricating oils, and more particularly to lubricating oils that can be suitably used for various industrial or automotive applications and have low evaporation properties and low viscosity at practical temperatures.

  In recent years, from the viewpoint of environmental issues, factories, transportation companies, etc. have been required to reduce power consumption and fuel consumption more than ever, and the lubricating oil used in various industrial machines and automobiles is also energy and fuel efficient. An effect is sought. As one of means for obtaining a power saving and fuel saving effect, there is a method of reducing friction by adding a friction modifier, but using a low viscosity base oil is also an effective method. In addition, various machines used at low temperatures such as in cold regions in winter are desired to have good low-temperature startability, but it is effective to use low-viscosity base oil as a means of improving this low-temperature startability. It is.

  On the other hand, as the performance of various machines is improved and the size and weight are reduced, lubricating oils are often used at high temperatures. Since the lubricating oil used in such locations tends to evaporate the base oil, further improvement in the evaporation characteristics (low evaporation) of the base oil is desired.

By the way, generally, when trying to improve the low evaporation property of the base oil, the kinematic viscosity tends to increase. On the other hand, if the base oil is used to improve the power saving and fuel saving effects and the low temperature startability, the kinematic viscosity of the base oil tends to be low. That is, there is a demand for a base oil that is used for a lubricating oil that has a low viscosity and a low viscosity and can be used for a long period of time in a wide temperature range from low to high temperatures. For example, Patent Document 1 discloses an aliphatic monocarboxylic acid ester oil, Patent Document 2 discloses a dibasic acid diester oil, and Patent Document 3 discloses a poly-α-olefin (PAO) oil.
JP 2002-146374 A JP 2003-34795 A JP 2006-176760 A

  An object of the present invention is to provide a base oil for lubricating oil and a lubricating oil which have a low viscosity and are excellent in low evaporation at a high temperature and can be used for a long time in a wide temperature range from a low temperature to a high temperature. is there.

In the present invention, the following lubricating base oil and lubricating oil are provided.
<1> An ester comprising an alcohol represented by the following general formula (1) and an unsaturated aliphatic linear monocarboxylic acid having 14 to 24 carbon atoms, wherein the ester has a total carbon number of 26 to 40 Ester base oil for lubricating oil.

  In formula (1), n and m are the same or different integers of 2 to 12.

<2> The ester base oil for lubricating oil according to <1>, wherein a difference between m and n in the general formula (1) is 2.

<3> A lubricating oil containing the ester base oil according to <1> or <2>.

  ADVANTAGE OF THE INVENTION According to this invention, the base oil for lubricating oil and lubricating oil which are low-viscosity and excellent in the low evaporation property under high temperature, and can be used for a long period of time in the wide temperature range from low temperature to high temperature are provided.

  As a result of intensive studies to solve the above problems, the inventors of the present invention formed an ester bond between an alcohol represented by the following general formula (1) and a carboxylic acid having 2 to 24 carbon atoms, and the total carbon of the ester. It has been found that the ester base oil for lubricating oil having a number of 26 to 40 has a low viscosity and is excellent in low evaporation at high temperatures.

In general formula (1), n and m are the integers of 2-12 which may be the same or different. Furthermore, the present inventors have found that the difference between m and n in the general formula (1) is 2, and the performance is further improved, and the present invention has been completed.
Hereinafter, the ester base oil for lubricating oil of the present invention and the lubricating oil containing the same will be described in detail.

<Ester base oil>
The ester base oil for lubricating oil of the present invention is an ester oil obtained by esterification of an alcohol of the following general formula (1) and a carboxylic acid having 2 to 24 carbon atoms.

  N and m in the general formula (1) may be the same or different integers of 2 to 12, preferably an integer of 3 to 10, more preferably an integer of 3 to 8. If n and m are too small, evaporability of the resulting ester oil is deteriorated (that is, evaporates easily). Conversely, if n and m are too large, the viscosity of the ester oil is increased. It is necessary to use an alcohol having an integer of ˜12. In addition, although n and m in General formula (1) may be the same or different, it will be especially low if the alcohol represented by General formula (1) whose difference between n and m is 2 is used. An ester oil having excellent evaporability is obtained, and is most preferable.

  Specific examples of the alcohol of the general formula (1) constituting the ester base oil of the present invention include 2-propylheptanol, 2-butyloctanol, 2-pentylnonanol, 2-hexyldecanol, 2-heptylundecanol, Examples include 2-octyldodecanol, 2-nonyltridecanol, 2-decyltetradecanol, and 2-undecylpentadecanol.

  On the other hand, the carboxylic acid constituting the ester base oil of the present invention has 2 to 24 carbon atoms, preferably 4 to 24, more preferably 4 to 22. If the carbon number is too small, it tends to evaporate, and if the carbon number is too large, the viscosity tends to increase. Therefore, the ester base oil is constituted using a carboxylic acid having a carbon number within the above range. The carboxylic acid may be any of carboxylic acids having a plurality of carboxyl groups such as dicarboxylic acid and tricarboxylic acid in addition to monocarboxylic acid. In addition, the carboxylic acid constituting the base oil of the present invention may be any of linear or branched, saturated or unsaturated, aliphatic, alicyclic, or aromatic.

  The saturated aliphatic monocarboxylic acid may be linear or branched, specifically, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecane Examples include acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, icosanoic acid, eicosanoic acid, henicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid and the like. These carboxylic acids include all isomers. Examples thereof include saturated alicyclic carboxylic acids such as cyclohexanecarboxylic acid.

  The unsaturated aliphatic monocarboxylic acid may be linear or branched, specifically, ethenoic acid, propenoic acid, butenoic acid, pentenoic acid, hexenoic acid, heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, Examples include undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid, nonadecenoic acid, icosenoic acid, eicosenoic acid, henicosenoic acid, docosenoic acid, tricosenoic acid, tetracosenoic acid and the like. These carboxylic acids include all isomers. Further, unsaturated alicyclic monocarboxylic acids such as 3-cyclohexenecarboxylic acid and aromatic monocarboxylic acids such as benzoic acid and naphthalenecarboxylic acid are also included.

  The saturated aliphatic dicarboxylic acid may be linear or branched, ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, Decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, icosanedioic acid, eicosanedioic acid, heikosansan Examples include acids, docosanedioic acid, tricosanedioic acid, and tetracosanedioic acid. These saturated fatty acids contain all isomers. In addition, saturated alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and dimer acid are also included.

  The unsaturated aliphatic dicarboxylic acid may be linear or branched, butenedioic acid, pentenedioic acid, hexenedioic acid, heptenedioic acid, octenedioic acid, nonenedioic acid, decenedioic acid, undecenedioic acid , Dodecenedioic acid, tridecenedioic acid, tetradecenedioic acid, pentadecenedioic acid, hexadecenedioic acid, heptadecenedioic acid, octadecenedioic acid, nonadecenedioic acid, icosendioic acid, eicosenedioic acid, heicocenedioic acid, dococenedioic acid, tricosene A diacid, tetracocene diacid, etc. are mentioned. These unsaturated fatty acids include all isomers. Further, unsaturated alicyclic dicarboxylic acids such as cis-4-cyclohexene-1,2-dicarboxylic acid and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid are also included.

  Examples of the tricarboxylic acid include aliphatic tricarboxylic acids such as aconitic acid, cyclohexanetricarboxylic acid, citric acid and isocitric acid, and aromatic tricarboxylic acids such as naphthalenetricarboxylic acid.

In carboxylic acids containing a plurality of carboxyl groups other than these, for example, naphthalenetetracarboxylic acid, benzenepentacarboxylic acid, melittic acid and the like can be used.
Animal and vegetable fatty acids such as beef tallow fatty acid, coconut oil fatty acid, and fish oil fatty acid may also be used.

  Of these carboxylic acids, monocarboxylic acids are preferred, aliphatic monocarboxylic acids are more preferred, and unsaturated aliphatic linear monocarboxylic acids are most preferred from the viewpoint of startability at low temperatures. In addition, since there exists a tendency for a viscosity to become high when there are too many carbon numbers when there are too few carbon numbers, since there exists a tendency for a viscosity to become high in any carbon number, the thing whose carbon number is 2-24 is used, but carbon More preferably, the number is 12-24, and most preferably 14-24.

  The ester base oil for lubricating oil of the present invention is an ester oil obtained by esterifying the above-mentioned alcohol and carboxylic acid. Since the viscosity tends to increase, the total carbon number is 26 to 40, more preferably 27 to 36, and most preferably 27 to 34.

<Lubricating oil composition>
The ester base oil of the present invention has a low viscosity and low evaporation by satisfying the above configuration, and can be used alone as a base oil for lubricating oil, or by mixing a plurality of ester base oils. It can also be used as a base oil for lubricating oil.
Further, when the lubricating oil composition is produced using the ester base oil of the present invention, other base oil components may be included as long as the kinematic viscosity and low evaporation property to be obtained are not impaired. Examples of the mineral oil base oil include base oil obtained by refining a lubricating oil fraction of crude oil by an appropriate combination such as solvent refining and hydrorefining. Examples of the synthetic lubricating base oil include poly-α-olefins, polyol esters, alkylbenzenes, polyglycols, phenyl ethers, and the like.
However, in order to sufficiently exhibit the performance of the ester base oil of the present invention and obtain a lubricating oil composition excellent in low viscosity and low evaporation, the ester base oil of the present invention is 30 to The content is preferably 100% by mass, more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, and particularly preferably no other base oil.

The lubricating oil composition of the present invention can be appropriately mixed with various additives as necessary.
Examples of additives include metal detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates; alkenyl succinimides, alkenyl succinimide boronated modified products, benzylamine, alkylpolyamines Dispersants such as zinc, sulfur, phosphorus, amine, ester, and other antiwear agents; polymethacrylate, ethylene propylene copolymer, styrene-isoprene copolymer hydride, polyisobutylene, etc. Various viscosity index improvers; alkylphenols such as 2,6-di-tert-butyl-p-cresol, bisphenols such as 4,4′-methylenebis- (2,6-di-t-butylphenol), n-octadecyl -3- (4'-hydroxy-3 ', 5'-di-tert-butyl Various antioxidants such as phenolic compounds such as ruphenol) propionate, aromatic amine compounds such as naphthylamines and dialkyldiphenylamines; sulfurized olefins, sulfurized fats and oils, methyltrichlorostearate, chlorinated naphthalene, benzylidated benzyl, fluoroalkyl Examples include extreme pressure agents such as polysiloxane and lead naphthenate; various rust inhibitors such as carboxylic acids such as stearic acid and dicarboxylic acid partial esters; and various corrosion inhibitors such as benzotriazole and benzimidazole.
These additives can be used singly or in combination of two or more. Further, the additive may be added as appropriate in such an amount that the effect of the additive can be exhibited and the low viscosity and low evaporating property of the ester base oil of the present invention are not impaired.

Next, the present invention will be specifically described with reference to examples. In addition, this invention is not limited at all by the following examples.
In the examples , reference examples, and comparative examples, the base oil components * 1 to * 12 shown below were evaluated.

* 1: Monoester oil A
Among the alcohols represented by the general formula (1), a mixture of n = 7 and m = 5, n = 8 and m = 6, and a mixture of oleic acid and linoleic acid were esterified. Obtained * 2: Monoester oil B
Among alcohols represented by the general formula (1), n is 7 and m is 5, and a product obtained by esterifying a mixture of oleic acid and linoleic acid * 3: Diester oil B
Dodecanedioic acid di-2-ethylhexyl * 4: PAO oil Polyalphaolefin having a kinematic viscosity at 40 ° C. of 17.32 mm ² / s * 5: Monoester oil G
Oleic acid oleyl

* 6: Monoester oil D
Among alcohols represented by the general formula (1), those obtained by esterifying n of 5 and m of 3 with linoleic acid * 7: Monoester oil E
Of the alcohol represented by the general formula (1), n is 7 and m is 5 and the product obtained by esterifying capric acid * 8: Monoester oil F
Of the alcohol represented by the general formula (1), n is 7 and m is 5 and myristic acid is esterified. * 9: Diester oil A
Di-2-ethylhexyl sebacate * 10: Diester oil C
Di-2-ethylhexyl adipate * 11: Monoester oil H
n-dodecanoic acid isotridecyl * 12: monoester oil I
Among the alcohols represented by the general formula (1), those obtained by esterifying those having n of 6 and m of 4 and capric acid

<Evaluation method>
(1) Kinematic viscosity A 40 ° C kinematic viscosity (mm ² / s) was evaluated by a kinematic viscosity test method established in JIS K 2283.
(2) Evaporability This is one of the methods for evaluating the thermal stability of a lubricating oil, and the evaporation loss (% by mass) was evaluated by a test based on the thermal oxidation stability test established in JIS K 2540.
Test conditions Temperature: 120 ° C
Time: 168 hrs

In Table 1 below, Examples , Reference Examples and Comparative Examples are shown for lubricants having an ISO viscosity grade equivalent to VG15, and Table 2 below for lubricants having an ISO viscosity grade equivalent to VG10.

  From Table 1 and Table 2, it can be seen that the ester oils of Examples 1 to 5 have a low kinematic viscosity and a smaller evaporation amount than the base oil of the comparative example of the same ISO viscosity grade.

Claims (3)

A lubricant comprising an alcohol represented by the following general formula (1) and an unsaturated aliphatic linear monocarboxylic acid having 14 to 24 carbon atoms, wherein the ester has a total carbon number of 26 to 40 Ester base oil.


(In formula (1), n and m are the same or different integers of 2 to 12)   The ester base oil for lubricating oil according to claim 1, wherein the difference between m and n in the general formula (1) is 2.   A lubricating oil containing the ester base oil according to claim 1.