JP5334432B2 - Grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition which is excellent in low torque properties at low temperature and low vaporizability at high temperature and which can be used for a long period of time in a wide temperature range from low temperature to high temperature. <P>SOLUTION: The grease composition has a base oil content of 40-97 mass% of the whole mass of the grease composition and contains the ester oil which is produced from an alcohol shown by general formula (1) (wherein n and m are each independently an integer of 2-12) and a 2-24C carboxylic acid and which is 30-100 mass% of the whole mass of the base oil. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  TECHNICAL FIELD The present invention relates to a grease composition that is used for lubricating parts such as automotive heat exchangers, air conditioners, and AV equipment, and that is excellent in low evaporation and low torque.

  In recent years, bearings, gears, and the like tend to be used at high temperatures as the speed of rotation is increased by reducing the size and weight of mechanical devices and improving the performance of equipment. In the grease used in such places, the base oil tends to evaporate, and if the base oil evaporates too much, the supply of oil to the lubrication surface decreases and the performance deteriorates. Therefore, the base oil used for such grease is desired to further improve the evaporation characteristics (low evaporation).

On the other hand, under a low temperature such as a cold district in winter, it is desired to start the machine smoothly, that is, to reduce the torque by reducing the viscosity of the base oil in the grease.
In addition, from the viewpoint of environmental issues, factories, transportation companies, etc. are required to reduce power and fuel consumption more than ever, and the grease used in various industrial machines and automobiles also has power and fuel saving effects. Is required. As one of means for obtaining a power saving and fuel saving effect, it is effective to lower the viscosity of the base oil.

  By the way, in general, the kinematic viscosity tends to increase when trying to improve the low evaporation property of the base oil, and the kinematic viscosity of the base oil tends to decrease when trying to improve the low torque property with the base oil. That is, there is a need for a grease that can further improve both the low evaporation property and the low torque property, which are contradictory properties, and can be used for a long time in a wide temperature range from a low temperature to a high temperature.

Under these circumstances, various trials using synthetic base oils such as carbonate ester oil, polyol ester oil, and diester oil were carried out for the purpose of developing a grease with excellent performance of both low evaporation and low torque. (For example, see Patent Documents 1 to 4).
JP-A-1-308496 JP 2001-72988 A JP 2001-3070 A JP 2003-327990 A

  An object of the present invention is to provide a grease composition which is excellent in low torque at low temperatures and low evaporation at high temperatures and can be used for a long time in a wide temperature range from low to high temperatures.

As a result of intensive studies to achieve the above object, the present inventor has found that an ester oil having a specific structure has a low viscosity while having a low viscosity. It was found that a grease that can be expected to achieve low torque and low torque at low temperatures and power saving effect can be obtained. The present invention has been completed based on these findings.
That is, the present invention
<1> The content of the base oil is 40 to 97% by mass with respect to the total amount of the grease composition, and the alcohol represented by the following general formula (1) and the aliphatic monocarboxylic acid having 2 to 24 carbon atoms the monoester oil consisting of a grease composition characterized in that it contains 30 to 100 wt% based on the total amount of base oil.

  In general formula (1), n and m each independently represent an integer of 2 to 12.

<2> The grease composition according to <1>, wherein a difference between m and n in the general formula (1) is 2.

<3> The total number of carbon atoms of the mono-ester oil composed of an alcohol and an aliphatic monocarboxylic acid having a carbon number of 2 to 24 represented by the general formula (1), characterized in that a 28 to 40 <1 > Or <2>.
<4> The thickener contains at least one selected from the group consisting of a lithium soap-based thickener and an N-substituted terephthalamic acid metal salt, and any one of <1> to <3> It is a grease composition as described in one.

  INDUSTRIAL APPLICABILITY The present invention can provide a grease composition that is excellent in low torque at a low temperature and low in 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.

The grease composition of the present invention will be described in detail.
The grease composition of the present invention has a base oil content of 40 to 97% by mass based on the total amount of the grease composition, and an alcohol represented by the following general formula (1) and a fat having 2 to 24 carbon atoms. family monoester oil consisting of a monocarboxylic acid (hereinafter sometimes referred to as "ester oils according to the present invention".) and characterized in that it contains 30 to 100 wt% based on the total amount of base oil.

  In the general formula (1), n and m each independently represent an integer of 2 to 12.

The alcohol represented by the general formula (1), which is one of the constituent components of the ester oil according to the present invention, will be described.
In General formula (1), n and m represent the integer of 2-12 each independently, Preferably it is an integer of 3-10, More preferably, it is an integer of 3-8. When at least one of n and m is less than 2, the evaporability is deteriorated, and when it exceeds 12, the viscosity tends to increase.
Further, from the viewpoint of evaporability, the difference between n and m is most preferably 2.

  Specific examples of the alcohol represented by the general formula (1) include 2-propylheptanol, 2-butyloctanol, 2-pentylnonanol, 2-hexyldecanol, 2-heptylundecanol, and 2-octyldodecanol. , 2-nonyltridecanol, 2-decyltetradecanol, 2-undecylpentadecanol, etc., among which 2-butyloctanol, 2-pentylnonanol, 2-hexyldecanol, 2-heptylundecane Nord is preferred.

Monocarboxylic acid which is one of the constituents of the ester oils according to the present invention (hereinafter sometimes referred to as "carboxylic acid according to the present invention".) Will be described.
The carboxylic acid according to the present invention has 2 to 24 carbon atoms, and the carbon number is preferably 6 to 24, and more preferably 10 to 22. When the number of carbon atoms is less than 2, the evaporability becomes poor, and when it exceeds 24, the viscosity tends to increase.

Since the alcohol according to the present invention has a branch, it is considered that an ester decomposition reaction caused by reacting with a fatty acid hardly occurs. Therefore, the carboxylic acid according to the present invention may be any of carboxylic acids having a plurality of carboxyl groups such as monocarboxylic acid, dicarboxylic acid, and tricarboxylic acid.
Further, the carboxylic acid according to the present invention may be either linear or branched, and may be any of saturated or unsaturated aliphatic, alicyclic, or aromatic.
In the present invention, the carboxylic acid according to the present invention is an aliphatic monocarboxylic acid.

The saturated aliphatic monocarboxylic acid as a specific example of the carboxylic acid according to the present invention may be linear or branched, specifically, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, Heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic 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. The saturated aliphatic monocarboxylic acid includes all isomers in the above specific examples.
In addition, saturated alicyclic carboxylic acids such as cyclohexanecarboxylic acid are also exemplified as specific examples of the carboxylic acid according to the present invention.

The unsaturated aliphatic monocarboxylic acid as a specific example of the carboxylic acid according to the present invention may be linear or branched, and specifically, ethenoic acid, propenoic acid, butenoic acid, pentenoic acid, hexenoic acid , Heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenic acid, octadecenoic acid, nonadecenoic acid, icosenic acid, eicosenoic acid, henicosenic acid, dococene Examples include acids, tricosenoic acid, and tetracosenoic acid. The saturated aliphatic monocarboxylic acid includes all isomers in the above specific examples.
In addition, unsaturated alicyclic monocarboxylic acids such as 3-cyclohexenecarboxylic acid and aromatic monocarboxylic acids such as benzoic acid and naphthalenecarboxylic acid are also exemplified as specific examples of the carboxylic acid according to the present invention.

The saturated aliphatic dicarboxylic acid as a specific example of the carboxylic acid according to the present invention may be linear or branched. Ethanedioic acid, propanedioic acid, butanedioic acid, pentanedioic acid, hexanedioic acid, heptane Diacid, octanedioic acid, nonanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid , Icosane diacid, eicosane diacid, henicosane diacid, docosane diacid, tricosane diacid, tetracosane diacid and the like. These saturated fatty acids contain all isomers.
In addition, saturated alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and dimer acid are also exemplified as specific examples of the carboxylic acid according to the present invention.

The unsaturated aliphatic dicarboxylic acid as a specific example of the carboxylic acid according to the present invention 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, heptacenedioic acid, octadecenedioic acid, nonadecenedioic acid, icosenedioic acid, eicosene diacid Examples thereof include acid, heicocene diacid, dococene diacid, tricocene diacid, and tetracocene diacid. These unsaturated fatty acids include all isomers.
In addition, 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 specific examples of the carboxylic acid according to the present invention. Can be mentioned.

  Examples of the tricarboxylic acid as a specific example of the carboxylic acid according to the present invention include aliphatic tricarboxylic acids such as aconitic acid, cyclohexanetricarboxylic acid, citric acid and isocitric acid, and aromatic tricarboxylic acids such as naphthalenetricarboxylic acid.

  In the carboxylic acid containing a plurality of carboxy groups other than the above specific examples, 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 preferable and aliphatic monocarboxylic acids are more preferable from the viewpoint of startability at low temperatures.
As carbon number in case the carboxylic acid which concerns on this invention is monocarboxylic acid, it is 2-24, 6-22 are preferable and 10-18 are still more preferable. When the number of carbon atoms is less than 2, the evaporability becomes poor, and when it exceeds 24, the viscosity tends to increase.
The ester oil composed of the alcohol represented by the general formula (1) and the carboxylic acid having 2 to 24 carbon atoms may be used singly or in combination of two or more.

  The total number of carbon atoms in the ester oil according to the present invention is preferably 28 to 40, more preferably 28 to 36, and most preferably 30 to 36. When the total carbon number of the ester oil according to the present invention is 28 to 40, the effect of low evaporation and low torque, which is the effect of the present invention, is further enhanced.

  In the grease composition of the present invention, the content of the ester oil according to the present invention relative to the total amount of the base oil is 30 to 100% by mass, and a base oil other than the ester oil according to the present invention, for example, a thickener synthesis described later. Base oils such as base oils and other ester oils used as a solvent may be included. 50-100 mass% is preferable and, as for content of the ester oil based on this invention with respect to the base oil whole quantity, 75-100 mass% is more preferable. When the ester oil according to the present invention is less than 30% by mass relative to the total amount of the base oil, the effects of low evaporation and low torque, which are the characteristics of the ester oil according to the present invention, cannot be sufficiently obtained. When considering only the performance of low evaporation and low torque, the more ester oil according to the present invention in the base oil, the more preferable, and most preferably 100% by mass.

  By the way, in a grease manufacturing method, a thickener may be synthesized using a base oil as a solvent. In this case, the thickener and the base oil are used as raw materials for the grease composition without being separated. Thus, when synthesizing the thickener in the base oil, the ester oil may be decomposed when the thickener is synthesized in the base oil containing the ester oil according to the present invention. Therefore, in such a case, the thickener is synthesized not in the base oil containing the ester oil according to the present invention but as a solvent with another base oil that does not easily decompose even if the thickener is synthesized. Then, it is preferable to blend the ester oil according to the present invention to produce the grease composition of the present invention.

  As the base oil used as a solvent for synthesizing such a thickener, poly-alpha olefin (hereinafter sometimes abbreviated as “PAO”), ether oil or mineral oil base oil is preferably used. At this time, the base oil used as the solvent for the thickener synthesis is preferably used in an amount of 5% by mass or more based on the total amount of the base oil of the grease composition of the present invention, considering the ease of the synthesis reaction. . On the other hand, since the base oil used as a solvent in synthesizing these thickeners will eventually be present in the grease composition of the present invention, the low evaporating property which is a characteristic of the ester oil according to the present invention In order to sufficiently obtain the effect of low torque, it is used so as to be 70% by mass or less, preferably 50% by mass or less, particularly preferably 25% by mass or less, based on the total amount of the base oil of the grease composition of the present invention. It is preferable to do.

Examples of the base oils PAO, ether oils, and mineral oil base oils that can be preferably used as the thickener synthesis solvent include the following.
Examples of PAO include α-olefin oligomers, which are polymers of α-olefins having 3 to 12 carbon atoms.
Examples of the mineral-based lubricating base oil include a product obtained by refining a lubricating oil fraction of crude oil in an appropriate combination such as solvent refining and hydrorefining.
Examples of the ether oil include polyphenyl ether having about 2 to 5 ether chains and about 3 to 6 phenyl groups.

Any base oil employed these thickener as a solvent in synthesizing, from satisfactorily maintain the viewpoint of low volatility of the grease composition, kinematic viscosity is preferably at least 1 mm 2 / ^s at 40 ° C., 5 mm ² / s or more is more preferable, and 7 mm ² / s or more is particularly preferable. On the other hand, the good keeping in view the low torque of the grease composition, kinematic viscosity is preferably from 40 mm ² / s at 40 ° C., more preferably not more than 35 mm ² / s, and particularly preferably 30 mm ² / s.

The kinematic viscosity at 40 ° C. of the base oil containing the ester oil according to the present invention (when using the base oil used as a solvent in synthesizing the thickener, the kinematic viscosity of all the base oils containing these base oils) is , preferably not less than ^{1 mm} 2 / s from the viewpoint of maintaining good low volatility, more preferably not less than ^{5 mm} 2 / s, most preferably at least 10 mm ² / s. On the other hand, the good keeping in view the low torque of the grease composition, is preferably from ^{50mm 2 / s, 40mm 2 /} s more preferably less, particularly preferably 30 mm ² / s or less, and most preferably less 25 mm ² / s .

  The content of the base oil (total amount of all base oil components) with respect to the total amount of the grease composition of the present invention is 40 to 97% by mass, preferably 50 to 95% by mass, and particularly preferably 60 to 90% by mass. %. When the content of the base oil is less than 40% by mass, the lubricity of the grease as a product is lowered, and when it exceeds 97% by mass, the grease does not become grease and an appropriate consistency cannot be obtained.

<Thickener>
Any thickener may be used as the thickener contained in the grease composition of the present invention, for example, lithium soap thickener, composite lithium soap thickener, polyurea and N-substituted metal terephthalate. Various thickeners such as salts or mixed systems thereof can be used.

Examples of the lithium soap thickener include an aliphatic carboxylic acid lithium salt having a hydroxyl group such as lithium-12-hydroxystearate, an aliphatic carboxylic acid lithium salt such as lithium stearate, or a mixture thereof.
Examples of the composite lithium soap thickener include a complex of an aliphatic carboxylic acid lithium salt having a hydroxyl group and a dibasic acid lithium salt. Here, suitable dibasic acids include succinic acid, malonic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid and the like.

  As the N-substituted terephthalamic acid metal salt, those represented by the following general formula (2) are preferably used.

In the general formula (2), ^{R 1} represents a hydrocarbon group having 4 to 22 carbon atoms, M represents a metal atom. The C 4-22 hydrocarbon group represented by R ¹ is preferably a C 4-22 alkyl group. The carbon number is preferably 14-20. When the carbon number is less than 4, the thickener is difficult to disperse in the base oil, and the base oil tends to separate. Moreover, when carbon number exceeds 22, there exists a tendency for shear stability to worsen. Specific examples of R ¹ include decyl group, tetradecyl group, hexadecyl group, octadecyl group and the like.

In the general formula (2), examples of the metal atom represented by M include atoms of periodic group I, II, III and IV metals, for example, lithium, aluminum, lead and the like. Particularly preferred are sodium, barium, lithium and potassium atoms, with the sodium atom being most preferred.
Z represents the same integer as the valence of M.

  As said polyurea, the compound represented by following General formula (3) is mentioned.

In General Formula (3), R ² and R ⁵ may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof. The preferred number of carbon atoms of R ² and ^{R 5} are 1-30, more preferably from 3 to 22, more preferably from 6 to 18. Examples of R ² and R ⁵ include hexyl group, octyl group, decyl group, tetradecyl group, hexadecyl group, octadecyl group, cyclohexyl group, benzyl group, phenyl group, tolyl group, naphthyl group and the like.

In the general formula (3), R ³ is a hydrocarbon having 1 to 30 carbon atoms, in order to introduce the R ³ is typically a diamine containing R ³ is used. Examples of diamines include ethylenediamine, octylenediamine, cyclohexylenediamine, phenylenediamine, tolylenediamine, dianiline methane, and ditoluidine methane.

In the general formula (3), R ⁴ is a hydrocarbon having 1 to 30 carbon atoms, in order to introduce R ^4, usually diisocyanates containing R ⁴ is used. Examples of diisocyanates include hexylene diisocyanate, octadecylene diisocyanate, phenylene diisocyanate, diphenylmethane-4,4-diisocyanate, tolylene diisocyanate and the like.
Moreover, in general formula (3), y represents the integer of 0-3, Preferably it is 0.

  As the thickener, the thickeners listed above can be used alone or in combination. However, the use of a lithium soap thickener or an N-substituted terephthalamic acid metal salt further reduces noise. It is preferable because it can be improved.

  The thickener imparts consistency to the grease composition.If the blending amount is too small, a proper consistency cannot be obtained without becoming a grease, and if the blending amount is too large, Lubricity tends to decrease. In order to provide an appropriate consistency and ensure lubricity as a grease, the blending amount of the thickener used in the present invention is 3 to 40% by mass, preferably 5%, based on the total amount of the grease composition. ˜20 mass%.

<Other additives>
The grease composition of the present invention can be appropriately mixed with various additives as required.
Examples of such various additives include metal detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates; alkenyl succinimides, alkenyl succinimide borated modified products, benzyl Dispersants such as amines and alkylpolyamines; alkylphenols such as 2,6-di-tert-butyl-p-cresol, bisphenols such as 4,4′-methylenebis- (2,6-di-t-butylphenol), Various antioxidants such as phenolic compounds such as n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-tert-butylphenol) propionate, aromatic amine compounds such as naphthylamines and dialkyldiphenylamines; Heavy sulfonic acid metal salt, polyhydric alcohol carbo Examples include various rust inhibitors such as acid partial esters; various corrosion inhibitors such as benzotriazole and benzimidazole.
In addition, the blending amount of these various additives is not limited to the total amount of the grease composition in order to prevent lowering of the low evaporation property and low torque property of the grease composition, which is the effect of the present invention, while exhibiting the effect of each additive. 0.01 to 10% by mass, more preferably 0.05 to 10% by mass, and still more preferably 0.05 to 8% by mass.

The present invention will be specifically described with reference to examples. In addition, this invention is not limited at all by these Examples.
<Examples 1-9, Comparative Examples 1-4>
A grease composition was prepared containing the components * 1 to * 14 shown below in the proportions (% by mass) shown in Table 1.
Here, among the thickeners (* 1 to * 5 components), when using each component of * 3 to * 5, the thickener is reacted by reacting the raw material of the thickener in the base oil by the method described later. After that, the base oil and the additive were mixed so as to have the ratio of the blending amount in the table, and as a result, a grease composition containing each component of * 1 to * 14 was prepared.
The grease composition was prepared by appropriately mixing the components * 1 to * 14 and milling to uniformly disperse the thickener in the grease.

* 1: Lithium-12-hydroxystearate In a heat-resistant container, the base oil shown in Table 1 (components of * 6 to * 13 below) and lithium-12-hydroxystearate (component of Sakai Chemical Co., Ltd.) which is a component of * 1 A product name; S7000H), heated, dissolved at about 200 ° C., added with a base oil, cooled, and then milled to obtain crystals of lithium-12-hydroxystearate. The grease compositions (Examples 1 to 4, 8 and Comparative Examples 1 to 4) having the composition described in Table 1 in which lithium-12-hydroxystearate is mixed and dispersed in the base oil Prepared.

* 2: Lithium-stearate In a heat-resistant container, the base oil described in Table 1 (* 6: Ester oil A), and lithium-stearate (product of Sakai Chemical; trade name: S7000) as * 2 component, Is heated at about 200 ° C., and the following * 6: Ester oil A is added, cooled, and milled to optimize the lithium-stearate crystals. A grease composition (Example 5) having the composition shown in Table 1 in which lithium stearate was mixed and dispersed in the oil was prepared.

* 3: Composite lithium soap Into a heat-resistant container, the following * 12: ether oil and 12-hydroxystearate are charged and heated. Next, an aqueous lithium hydroxide solution is added at about 80 ° C., and lithium-12-hydroxystearate is generated by a saponification reaction. Further, lithium hydroxide and azelaic acid are added at about 90 ° C. and reacted for about 2 hours to produce a lithium complex soap (complex lithium soap) which is a * 3 component. Then, after heating and semi-dissolving, the following * 6: Ester oil A was added and quenched to optimize the crystal of lithium-12-hydroxystearate / azelaic acid complex soap. A grease composition (Example 6) having the composition shown in Table 1 in which lithium-12-hydroxystearate / azelaic acid complex soap was mixed and dispersed therein was prepared.

* 4: Sodium N-substituted terephthalamate In a heat-resistant container, the following * 12: ether oil and methyl ester of N-octadecyl terephthalamic acid are added and dissolved by heating, and then cooled to 100 ° C or lower. Add 50% by weight sodium hydroxide aqueous solution, heat gradually with good agitation, saponify sufficiently, and after saponification, add further base oil at 150 ° C and heat to the maximum temperature of 180 ° C. Add oil A and cool to 60 ° C to optimize the crystals of * 4 component sodium N-octadecyl terephthalate, and mix and disperse sodium N-octadecyl terephthalate in the base oil. A grease composition (Example 7) having the composition shown in Table 1 was prepared. In addition, sodium N-octadecyl terephthalate is a thing of R < ¹ >, N-octadecyl group, M is sodium, and z is 1 in General formula (2).

* 5: Aliphatic diurea The following * 6: Ester oil A and diphenylmethane-4,4-diisocyanate are added to a heat-resistant container, heated, and then octylamine is added at about 60 ° C., about 40 The mixture is heated to 170 ° C. with stirring, and the following * 6: Ester oil A is added, cooled, and then milled to optimize the crystal of the aliphatic diurea, which is a * 5 component. A grease (Example 9) having the composition shown in Table 1 was prepared in which aliphatic diurea was mixed and dispersed in the base oil. The obtained aliphatic diurea is an aliphatic diurea in which R ² and R ⁵ are octyl groups, R ³ is an aromatic hydrocarbon group having 13 carbon atoms, and y is 0 in the general formula (3). It is.

* 6: Ester oil A
In the general formula (1), a mixed alcohol obtained by mixing an alcohol in which n is 7 and m is 5 and an alcohol in which n is 8 and m is 6, and oleic acid (unsaturated aliphatic carboxylic acid having 18 carbon atoms) Acid) and a mixture of linoleic acid (unsaturated aliphatic carboxylic acid having 18 carbon atoms) and ester obtained by esterification (mixture of 34 and 36 total carbon esters) was used as ester oil A.

* 7: Ester oil B
In the general formula (1), an alcohol having n of 7 and m of 5, oleic acid (unsaturated aliphatic carboxylic acid having 18 carbon atoms) and linoleic acid (unsaturated aliphatic carboxylic acid having 18 carbon atoms) An ester obtained by esterifying the mixture (ester having a total carbon number of 34) was designated as ester oil B.

* 8: Ester oil C
In the general formula (1), a mixed alcohol of an alcohol in which n is 5 and m is 3, an alcohol in which n is 6 and m is 4, and an alcohol in which n is 7 and m is 5, and oleic acid (carbon An ester obtained by esterifying a mixture of an unsaturated aliphatic carboxylic acid having 18 carbon atoms and linoleic acid (an unsaturated aliphatic carboxylic acid having 18 carbon atoms) (a mixture of esters having 30, 32 and 34 carbon atoms in total) Ester oil C was designated.

* 9: Ester oil D
In general formula (1), an ester obtained by esterifying alcohol having n of 7 and m of 5 and myristic acid (saturated aliphatic carboxylic acid having 14 carbon atoms) (ester having 30 carbon atoms in total) ) As ester oil D.

* 10: Ester oil E
Oleyl oleate was designated as ester oil E.

* 11: Polyol ester oil A polyol ester oil obtained by adding an aliphatic carboxylic acid having 8 to 10 carbon atoms to pentaerythritol was used. The kinematic viscosity of this polyol ester oil at 40 ° C. was 29.92 mm ² / s.

* 12: Ether oil A diphenyl ether oil having at least one branched hydrocarbon group having 16 carbon atoms in one molecule. The kinematic viscosity of this ether oil at 40 ° C. was 21.5 mm ² / s.

* 13: PAO
A polyalphaolefin having a kinematic viscosity at 40 ° C. of 17.32 mm ² / s was designated as * 13: PAO.

* 14: Antioxidant Octylated phenyl-α-naphthylamine was used as * 14: antioxidant.

<Measurement (evaluation) method>
(1) Kinematic viscosity of base oil The kinematic viscosity (mm ² / s) at 40 ° C. and 100 ° C. of the base oil used in the grease composition was measured by a kinematic viscosity test method established in JISK 2283. The results are shown in Table 1.

(2) Evaporability at high temperature The obtained grease composition was applied as a thin film having a length of 20 mm, a width of 50 mm, and a thickness of 2 mm on a metal plate, and the metal plate was allowed to stand in an air bath at 120 ° C. for 168 hours. The amount of mass loss before and after was defined as the evaporation amount [% by mass]. The results are shown in Table 1.

(3) Torque property at low temperature It was performed according to the low temperature torque test method of JIS K2200, and the starting torque (mN · m) at −40 ° C. was obtained as a condition. The results are shown in Table 1.

(4) Acoustic characteristics (low noise)
Low noise characteristics were measured using a general Anderon meter to measure the acoustic characteristics of the bearing. The Anderon meter is a device that extracts a vibration component in the transmission radial direction from the inside to the outside and outputs it as sound from a speaker when the outer ring of the bearing is fixed and the inner ring is rotated at a constant speed. Specifically, a JIS nominal number 608 bearing was used as the Anderon meter bearing, 0.3 g of grease was charged, and the Anderon value of the high band was measured when rotated for 1 minute at a rotation speed of 1800 rpm and a thrust load of 2 kgf. And evaluated according to the following criteria. The results are shown in Table 1.
The acoustic characteristics (low noise property) are better as the Anderon value is lower.
The evaluation was carried out according to the following criteria with the target of an Anderon value of less than 1.5.
A: Anderon value is less than 1.5.
Δ: Anderon value is 1.5 or more and less than 2.5.
X: Anderon value is 2.5 or more.

  From Table 1, it can be seen that the grease compositions of Examples 1 to 9 are excellent in low torque properties at low temperatures and low evaporation properties at high temperatures.

Claims (4)

Mono consisting content of the base oil is 40 to 97 wt% based on the total amount of the grease composition, and the alcohol and an aliphatic monocarboxylic acid having a carbon number of 2 to 24 represented by the following general formula (1) A grease composition comprising 30 to 100% by mass of ester oil based on the total amount of base oil.


(In general formula (1), n and m each independently represents an integer of 2 to 12.)   The grease composition according to claim 1, wherein a difference between m and n in the general formula (1) is 2. The total number of carbon atoms of the mono-ester oil composed of an alcohol and an aliphatic monocarboxylic acid having a carbon number of 2 to 24 represented by the general formula (1) is, according to claim 1 or claim, which is a 28 to 40 Item 3. The grease composition according to Item 2.   It contains at least 1 sort (s) chosen from the group which consists of a lithium soap type | system | group thickener and N-substituted terephthalamic acid metal salt as a thickener, The any one of Claims 1-3 characterized by the above-mentioned. Grease composition.