Lubricating composition and lubricant composition that includes the lubricating composition

Abstract

To provide a lubricating composition that shows good friction reduction effect.SOLUTION: A lubricating composition includes a polyester (A) obtained by reacting a dibasic acid component having 4 to 12 carbon atoms, one or more glycol components selected from the group consisting of 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, and 1,4-butanediol, a hydroxy acid component including 12-hydroxystearic acid, and one or more terminating components selected from the group consisting of a monovalent fatty acid having 8 to 12 carbon atoms and a linear monohydric alcohol having 6 to 10 carbon atoms, and a fatty acid ester (B) that is an ester of a compound having 3 to 6 hydroxyl groups within the molecule and a linear fatty acid having 6 to 18 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a lubricating composition that exhibits good friction-reducing effects. [Background technology]

[0002] In lubricants such as lubricating oils, hydraulic oils, and processing oils, lubricant compositions such as additives and base oils with excellent friction and wear properties are used to extend the life of equipment and machinery. For example, Patent Document 1 describes a lubricating oil composition containing a polyol ester synthesized from neopentyl glycol and a fatty acid, and a sulfurized oleic acid ester. Patent Document 2 describes a lubricating oil composition containing at least one sugar polyol and at least one C6-C 11 Esters with linear fatty acids are described in which the sugar polyol is erythritol.

[0003] Patent Document 3 describes a lubricating oil composition containing a Fischer-Tropsch derived base oil, a polyalphaolefin, an ester compound which is an ester of a trivalent or higher polyol, and a partial ester compound of an unsaturated fatty acid and a polyol. Patent Document 4 describes a refrigerator oil composition containing one or more polyol ester compounds selected from the group consisting of complete esters and partial esters of a pentaerythritol compound and a fatty acid including a short-chain fatty acid having from 2 to 9 carbon atoms. Patent Document 5 describes a refrigerator oil composition containing diglycerin and at least one C 14 ~C 24 A liquid organic lubricant is described, which is characterized by containing an ester product having a number average molecular weight of more than 3800 g / mol, obtained by esterification of a composition containing a monobasic acid component and a dibasic acid component, each of which contains a branched fatty acid. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-046486 [Patent Document 2] Special Publication No. 2022-519217 [Patent Document 3] Patent Publication No. 2021-066795 [Patent Document 4] Japanese Patent Publication No. 2023-085083 [Patent Document 5] Patent Publication No. 2021-014579 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with such conventional compositions, sufficient friction-reducing effects are still not exhibited, and there are problems in improving the friction performance of lubricating oils and fuel oils. Therefore, an object of the present invention is to provide a lubricating composition that exhibits good friction-reducing effects. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have discovered a lubricating composition that exhibits a good friction-reducing effect, and have thus completed the present invention. Specifically, the present invention provides a lubricating composition containing a polyester (A) obtained by reacting a dibasic acid component having 4 to 12 carbon atoms with one or more glycol components selected from the group consisting of 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, and 1,4-butanediol, a hydroxy acid component including 12-hydroxystearic acid, and one or more end-termining components selected from the group consisting of monovalent fatty acids having 8 to 12 carbon atoms and linear monohydric alcohols having 6 to 10 carbon atoms, and a fatty acid ester (B) which is an ester of a compound having 3 to 6 hydroxyl groups in the molecule with a linear fatty acid having 6 to 18 carbon atoms, wherein the content of the polyester (A) in the lubricating composition is 10 to 85 mass% and the content of the fatty acid ester (B) is 15 to 90 mass% relative to the total amount of the lubricating composition. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a lubricating composition that exhibits a good friction-reducing effect. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. Lubricating composition The lubricating composition of the present invention is characterized by containing a polyester (A) obtained by reacting specific components and a specific fatty acid ester (B). The lubricating composition of the present invention will be described in detail below.

[0009] 1. Polyester (A) The polyester (A) used in the present invention is a polyester obtained by reacting a dibasic acid component having 4 to 12 carbon atoms with one or more glycol components selected from the group consisting of 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, and 1,4-butanediol, a hydroxy acid component including 12-hydroxystearic acid, and one or more end-terminated components selected from the group consisting of monovalent fatty acids having 8 to 12 carbon atoms and linear monohydric alcohols having 6 to 10 carbon atoms. In the present invention, by using a polyester obtained using a specific dibasic acid component, glycol component, and hydroxy acid component, as well as the end-terminated component, a lubricating composition that exhibits a good friction-reducing effect can be obtained due to the synergistic effect when combined with the fatty acid ester (B) described below.

[0010] 1-1. Dibasic acid components The dibasic acid component used in producing the polyester (A) is a dibasic acid component having 4 to 12 carbon atoms. Examples of such dibasic acid components include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, phthalic acid, isophthalic acid, and terephthalic acid. Among these, in the present invention, from the viewpoint of obtaining a polyester (A) that exhibits a better friction-reducing effect when combined with the fatty acid ester (B), it is preferable to use an aliphatic dibasic acid having 4 to 12 carbon atoms as the dibasic acid component, more preferably one or more selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, even more preferably one or more selected from the group consisting of adipic acid, sebacic acid, and azelaic acid, and particularly preferably sebacic acid.

[0011] 1-2. Glycol components The glycol component used in the present invention is one or more selected from the group consisting of 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, and 1,4-butanediol. In the present invention, from the viewpoint of obtaining a polyester (A) that exhibits a better friction-reducing effect when combined with a fatty acid ester (B), it is preferable to use 1,2-propylene glycol or 1,3-propylene glycol as the glycol component, and it is more preferable to use 1,2-propylene glycol.

[0012] 1-3. Hydroxy acid ingredients The hydroxy acid component used in the present invention is a hydroxy acid component containing 12-hydroxystearic acid. The hydroxy acid component used in the present invention may consist solely of 12-hydroxystearic acid, or may further contain other hydroxy acids such as ricinoleic acid, glycolic acid, or lactic acid. In the present invention, from the viewpoint of obtaining a polyester (A) that exhibits a better friction-reducing effect when combined with a fatty acid ester (B), it is preferable to use a hydroxy acid component containing 50% by mass or more of 12-hydroxystearic acid, more preferably a hydroxy acid component containing 80% by mass or more of 12-hydroxystearic acid, and even more preferably a hydroxy acid component consisting solely of 12-hydroxystearic acid.

[0013] 1-4. Terminal termination component The end-stopping component used in the present invention is one or more end-stopping components selected from the group consisting of monovalent fatty acids having 8 to 12 carbon atoms and linear monohydric alcohols having 6 to 10 carbon atoms. Examples of monovalent fatty acids having 8 to 12 carbon atoms include n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, and n-dodecanoic acid. Examples of linear monohydric alcohols having 6 to 10 carbon atoms include 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol. In the present invention, from the viewpoint of obtaining polyester (A) that exhibits a better friction-reducing effect when combined with fatty acid ester (B), it is preferable to use a monovalent fatty acid having 8 to 12 carbon atoms as the end-stopping component, more preferably octanoic acid, nonanoic acid, decanoic acid, or dodecanoic acid, and even more preferably octanoic acid.

[0014] The dibasic acid component, glycol component, hydroxy acid component, and end-terminated component used in the present invention may each be derived from a petroleum raw material, or from a plant, animal, or microorganism itself, or from a biomass raw material that is a resource obtained from these, and can be appropriately selected depending on the purpose. In the present invention, "derived from a biomass raw material" refers to a plant, animal, or microorganism itself, or a resource obtained from these, and does not include those derived from fossil fuels such as petroleum, coal, or natural gas.

[0015] The polyester (A) used in the present invention is a polyester obtained by reacting the dibasic acid component, glycol component, hydroxy acid component, and end-terminated component described above. More specifically, it is a polyester having a structure resulting from the reaction of a carboxylic acid group present in the dibasic acid component, a hydroxyl group present in the glycol component, a carboxylic acid group and a hydroxyl group present in the hydroxy acid component, and a carboxylic acid group and / or a hydroxyl group present in the end-terminated component. The structure of such a polyester is thought to vary significantly depending on the structure of each component used and the ratio of each raw material, so it is impossible or impractical to directly specify the structure of the polyester (A) used in the present invention by a general formula or the like. Therefore, the polyester (A) must be defined as "a polyester obtained by reacting a dibasic acid component, a glycol component, a hydroxy acid component, and an end-terminated component."

[0016] 1-5. Number average molecular weight of polyester (A) From the viewpoint of the friction-reducing effect when combined with the fatty acid ester (B), the number-average molecular weight of the polyester (A) used in the present invention is preferably 700 to 10,000, more preferably 800 to 7,000, and even more preferably 1,000 to 4,500. The number-average molecular weight of the polyester (A) of the present invention is a value calculated in terms of polystyrene by subjecting a sample prepared by dissolving 50 mg of the sample in 10 mL of tetrahydrofuran to peak splitting analysis using a semi-micro GPC column (SHODEX KF-402.5 manufactured by Showa Denko K.K.) and a differential refractometer detector.

[0017] 1-6. Acid value of polyester (A) The acid value of the polyester (A) used in the present invention is preferably 0 to 10.0 mgKOH / g, more preferably 0 to 3.0 mgKOH / g, and even more preferably 0 to 2.0 mgKOH / g, from the viewpoint of the friction-reducing effect when combined with the fatty acid ester (B). The acid value of the polyester (A) of the present invention is measured by a method in which a sample is weighed out to the nearest 10 mg in a container, sufficiently dissolved in a neutral toluene / ethanol solution, a few drops of phenolphthalein indicator are added, and the sample is titrated with a 0.1 N KOH aqueous solution.

[0018] 1-7. Hydroxyl value of polyester (A) The hydroxyl value of the polyester (A) used in the present invention is preferably 0 to 30.0 mgKOH / g, more preferably 3.0 to 20.0 mgKOH / g, from the viewpoint of the friction-reducing effect when combined with the fatty acid ester (B). The hydroxyl value of the polyester (A) is measured by precisely weighing a sample to the nearest 10 mg into a container, thoroughly dissolving it in 10 mL of triethyl phosphate, adding 10.85 g of 60% perchloric acid and 18 mL of acetic anhydride to 900 mL of triethyl phosphate, mixing, and then adding 15 mL of reagent (a) prepared by adding 93 mL of acetic anhydride, stirring thoroughly, adding 20 mL of reagent (d) prepared by mixing pyridine and distilled water in a 3:1 volume ratio, allowing to stand for 5 minutes, adding 50 mL of neutral isopropyl alcohol, adding a few drops of phenolphthalein indicator, and titrating with 1.0 N KOH aqueous solution.

[0019] 1-8. Manufacturing method of polyester (A) The method for producing the polyester (A) used in the present invention is not particularly limited as long as it is a method that can react the above-mentioned dibasic acid component, glycol component, hydroxy acid component, and end-stop component, and for example, known polyester production methods can be used. Examples of such methods include a method in which the dibasic acid component, glycol component, hydroxy acid component, and end-stop component are mixed, optionally using a catalyst, in a solvent or without a solvent, at a temperature of 120°C to 260°C, preferably 180°C to 250°C, more preferably 200°C to 230°C, under a pressurized environment, a reduced pressure environment, or a normal pressure environment, and maintained for 10 minutes to 20 hours until the reaction is complete.

[0020] The amounts of the dibasic acid component, glycol component, hydroxy acid component, and end-capping component used in producing the polyester (A) used in the present invention are not particularly limited and can be adjusted appropriately depending on the purpose. However, from the viewpoint of obtaining a polyester (A) that exhibits a better friction-reducing effect when combined with the fatty acid ester (B), the proportions of the dihydrochloric acid component, glycol component, hydroxy acid component, and end-capping component used, expressed as a mass ratio relative to the total amount of raw materials used, are preferably 20 to 70 mass% for the dibasic acid component, 15 to 50 mass% for the glycol component, 5 to 40 mass% for the hydroxy acid component, and 3 to 50 mass% for the end-capping component, and more preferably 30 to 60 mass% for the dibasic acid component, 20 to 40 mass% for the glycol component, 10 to 30 mass% for the hydroxy acid component, and 5 to 40 mass% for the end-capping component, respectively.

[0021] The catalyst that can be used when reacting the dibasic acid component, the glycol component, the hydroxy acid component, and the terminal blocking component can be a known catalyst. Examples of such catalysts include acidic catalysts such as sulfuric acid, phosphoric acid, zinc chloride, benzenesulfonic acid, p-toluenesulfonic acid, and 4-chlorobenzenesulfonic acid; alkoxytitanium compounds such as tetramethoxytitanium, tetraethoxytitanium, and tetraisopropoxytitanium; titanium acylate compounds such as polyhydroxytitanium stearate and polyisopropoxytitanium stearate; titanium chelate compounds such as titanium acetylacetate, triethanolamine titanate, titanium ammonium lactate, titanium ethyl lactate, and titanium octylene glycolate; tin compounds such as dibutyltin dilaurate, dibutyltin oxide, and dibutyltin diacetate; metal acetates such as magnesium acetate, calcium acetate, and zinc acetate; and metal oxides such as antimony oxide and zirconium oxide. One or more of these can be used.

[0022] 2. Fatty acid ester (B) The fatty acid ester (B) used in the present invention is an ester of a compound having 3 to 6 hydroxyl groups in the molecule and a straight-chain fatty acid having 6 to 18 carbon atoms, more specifically, an ester obtained by reacting a hydroxy group in a compound having 3 to 6 hydroxyl groups in the molecule with a carboxy group in a straight-chain fatty acid having 6 to 18 carbon atoms. Among these, examples of the compound having 3 to 6 hydroxyl groups in the molecule include trimethylolethane, trimethylolpropane, trimethylolbutane, ditrimethylolethane, ditrimethylolpropane, ditrimethylolbutane, pentaerythritol, dipentaerythritol, glycerin, and sorbitol. Examples of straight-chain fatty acids having 6 to 18 carbon atoms include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, 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. In the present invention, the ester of a compound having 3 to 6 hydroxyl groups in the molecule with a straight-chain fatty acid having 6 to 18 carbon atoms may be a monoester, a partial ester, or a full ester. However, from the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A), a fatty acid ester having the acid value and hydroxyl value described below is preferred. In the present invention, by using a specific ester as the fatty acid ester (B), a lubricating composition exhibiting a good friction-reducing effect can be obtained due to the synergistic effect when combined with the polyester (A).

[0023] In the present invention, from the viewpoint of obtaining a lubricating composition that exhibits a better friction-reducing effect when combined with polyester (A), the compound having 3 to 6 hydroxyl groups in the molecule is preferably one or more selected from the group consisting of trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, and dipentaerythritol, more preferably one or more selected from the group consisting of trimethylolpropane, pentaerythritol, and dipentaerythritol, and even more preferably trimethylolpropane, pentaerythritol, or a mixture thereof. Furthermore, from the viewpoint of obtaining a lubricating composition that exhibits a better friction-reducing effect when combined with polyester (A), the straight-chain fatty acid having 6 to 18 carbon atoms is preferably a straight-chain fatty acid having 6 to 16 carbon atoms, more preferably a straight-chain fatty acid having 6 to 14 carbon atoms, and even more preferably a straight-chain fatty acid having 6 to 12 carbon atoms. Among these, in the present invention, it is particularly preferred that the fatty acid ester (B) is one or more fatty acid esters selected from the group consisting of esters of trimethylolpropane and linear fatty acids having 6 to 12 carbon atoms and esters of pentaerythritol and linear fatty acids having 6 to 12 carbon atoms, from the viewpoint that a lubricating composition that exhibits particularly good friction-reducing effect can be obtained when combined with the polyester (A).

[0024] More specifically, the ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms that can be preferably used in the present invention is an ester obtained by reacting a hydroxy group in trimethylolpropane with a carboxy group in the straight-chain fatty acid having 6 to 12 carbon atoms. The ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms may be a monoester, a diester, or a triester, but is preferably a triester having an acid value and a hydroxyl value described below.

[0025] In the ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms that can be preferably used in the present invention, examples of the straight-chain fatty acid having 6 to 12 carbon atoms include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, and n-dodecanoic acid, and one or more of these can be used. Among these, from the viewpoint of exhibiting a better friction-reducing effect when combined with polyester (A), one or more selected from the group consisting of n-heptanoic acid, n-octanoic acid, and n-decanoic acid are preferred, two or more selected from the group consisting of n-heptanoic acid, n-octanoic acid, and n-decanoic acid are more preferred, and n-heptanoic acid, n-octanoic acid, and n-decanoic acid are even more preferred. When a mixed ester of trimethylolpropane and a linear fatty acid consisting of n-heptanoic acid, n-octanoic acid, and n-decanoic acid is used as the fatty acid ester (B) used in the present invention, it is preferable to use a mixed triester of trimethylolpropane and a linear fatty acid mixture consisting of 0.1 to 20 mol % of n-heptanoic acid, 60 to 99.5 mol % of n-octanoic acid, and 0.1 to 30 mol % of n-decanoic acid, from the viewpoint of exhibiting a better friction-reducing effect when combined with polyester (A), and it is preferable to use a mixed triester of trimethylolpropane and a linear fatty acid mixture consisting of 0.2 to 10 mol % of n-heptanoic acid, 80 to 99.5 mol % of n-octanoic acid, and It is more preferable to use a mixed triester of trimethylolpropane and a straight-chain fatty acid mixture consisting of 0.5 to 5.0 mol% of n-heptanoic acid, 90 to 98 mol% of n-octanoic acid, and 1.0 to 5.0 mol% of n-decanoic acid, and it is even more preferable to use a mixed triester of trimethylolpropane and a straight-chain fatty acid mixture consisting of 0.8 to 2.0 mol% of n-heptanoic acid, 94 to 97 mol% of n-octanoic acid, and 2.0 to 4.0 mol% of n-decanoic acid.

[0026] More specifically, the ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms that can be preferably used in the present invention is an ester obtained by reacting a hydroxy group in pentaerythritol with a carboxy group in the linear fatty acid having 6 to 12 carbon atoms. The ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms may be a monoester, a diester, a triester, or a tetraester, but is preferably a tetraester having an acid value and a hydroxyl value described below.

[0027] In the ester of pentaerythritol and a straight-chain fatty acid having 6 to 12 carbon atoms that can be preferably used in the present invention, examples of the straight-chain fatty acid having 6 to 12 carbon atoms include n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, and n-dodecanoic acid, and one or more of these can be used. Among these, from the viewpoint of exhibiting a better friction-reducing effect when combined with polyester (A), one or more selected from the group consisting of n-heptanoic acid, n-octanoic acid, and n-decanoic acid are preferred, one or more selected from the group consisting of n-octanoic acid and n-decanoic acid are more preferred, and n-octanoic acid and n-decanoic acid are even more preferred. When a mixed ester of pentaerythritol and a linear fatty acid consisting of n-octanoic acid and n-decanoic acid is used as the fatty acid ester (B) used in the present invention, from the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A), it is preferable to use a mixed tetraester of pentaerythritol and a linear fatty acid mixture consisting of 70 to 99 mol% n-octanoic acid and 1 to 30 mol% n-decanoic acid, it is more preferable to use a mixed tetraester of pentaerythritol and a linear fatty acid mixture consisting of 80 to 98 mol% n-octanoic acid and 2 to 20 mol% n-decanoic acid, it is even more preferable to use a mixed tetraester of pentaerythritol and a linear fatty acid mixture consisting of 85 to 97 mol% n-octanoic acid and 3 to 15 mol% n-decanoic acid, and it is particularly preferable to use a mixed tetraester of pentaerythritol and a linear fatty acid mixture consisting of 90 to 96 mol% n-octanoic acid and 4 to 10 mol% n-decanoic acid.

[0028] The fatty acid ester (B) used in the present invention preferably contains an ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms, from the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A). Furthermore, in the present invention, from the viewpoint of exhibiting a particularly good friction-reducing effect when combined with the polyester (A), it is more preferable to use, as the fatty acid ester (B), a fatty acid ester consisting of an ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms, or a fatty acid ester consisting of a mixture of an ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms and an ester of pentaerythritol and a straight-chain fatty acid having 6 to 12 carbon atoms, and it is more preferable to use, as the fatty acid ester (B), a fatty acid ester consisting of an ester of trimethylolpropane and a straight-chain fatty acid having 7 to 10 carbon atoms, or a fatty acid ester consisting of a mixture of an ester of trimethylolpropane and a straight-chain fatty acid having 6 to 12 carbon atoms and an ester of pentaerythritol and a straight-chain fatty acid having 6 to 12 carbon atoms. It is even more preferable to use a fatty acid ester consisting of a mixture of an ester of a straight-chain fatty acid having 7 to 10 carbon atoms and an ester of pentaerythritol and a straight-chain fatty acid having 8 to 10 carbon atoms, and it is particularly preferable to use a fatty acid ester consisting of a mixed ester of trimethylolpropane and a straight-chain fatty acid consisting of n-heptanoic acid, n-octanoic acid, and n-decanoic acid, or a fatty acid ester consisting of a mixed ester of trimethylolpropane and a straight-chain fatty acid consisting of n-heptanoic acid, n-octanoic acid, and n-decanoic acid and a mixed ester of pentaerythritol and a straight-chain fatty acid consisting of n-octanoic acid and n-decanoic acid.

[0029] When the fatty acid ester (B) used in the present invention contains an ester of trimethylolpropane and a linear fatty acid having 6 to 12 carbon atoms and an ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms, the ratio of the ester of trimethylolpropane and a linear fatty acid having 6 to 12 carbon atoms to the ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms is not particularly limited and can be adjusted appropriately depending on the purpose. However, from the viewpoint of exhibiting a better friction-reducing effect when combined with polyester (A), the content of the ester of trimethylolpropane and a linear fatty acid having 6 to 12 carbon atoms in the fatty acid ester (B) to the ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms is preferably 20:80 to 90:10, and more preferably 30:70 to 85:15, by mass.

[0030] 2-1. Acid value of fatty acid ester (B) From the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A), the acid value of the fatty acid ester (B) used in the present invention is preferably 0 to 10.0 mgKOH / g, more preferably 0 to 3.0 mgKOH / g, and even more preferably 0 to 2.0 mgKOH / g. In the present invention, the acid value of the fatty acid ester (B) is measured by a method in which a sample is weighed out to the nearest 10 mg in a container, sufficiently dissolved in a neutral toluene / ethanol solution, a few drops of phenolphthalein indicator are added, and the solution is titrated with a 0.1 N KOH aqueous solution.

[0031] The acid value of the ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms as the fatty acid ester (B) preferably usable in the present invention is preferably 0 to 10.0 mgKOH / g, more preferably 0 to 3.0 mgKOH / g, and even more preferably 0 to 2.0 mgKOH / g, from the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A).

[0032] 2-2. Hydroxyl value of fatty acid ester (B) The hydroxyl value of the fatty acid ester (B) used in the present invention is preferably 0 to 30.0 mgKOH / g, more preferably 0.1 to 20.0 mgKOH / g, from the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A). In the present invention, the hydroxyl value of the fatty acid ester (B) is measured by a method in which a sample is accurately weighed to the nearest 10 mg in a container, thoroughly dissolved in 10 mL of triethyl phosphate, 10.85 g of 60% perchloric acid and 18 mL of acetic anhydride are added to 900 mL of triethyl phosphate, and after mixing, 15 mL of reagent (a) prepared by adding 93 mL of acetic anhydride is added and thoroughly stirred, and then 20 mL of reagent (d) prepared by mixing pyridine and distilled water in a volume ratio of 3:1 is added, and the mixture is allowed to stand for 5 minutes. After that, 50 mL of neutral isopropyl alcohol is added, a few drops of phenolphthalein indicator are added, and the mixture is titrated with a 1.0 N KOH aqueous solution.

[0033] The hydroxyl value of the ester of pentaerythritol and a linear fatty acid having 6 to 12 carbon atoms as the fatty acid ester (B) preferably usable in the present invention is preferably 0 to 30.0 mgKOH / g, more preferably 0.1 to 20.0 mgKOH / g, from the viewpoint of exhibiting a better friction-reducing effect when combined with the polyester (A).

[0034] 2-3. Method for producing fatty acid ester (B) The method for producing the fatty acid ester (B) used in the present invention, which is an ester of a compound having 3 to 6 hydroxyl groups in the molecule and a straight-chain fatty acid having 6 to 18 carbon atoms, is not particularly limited, and a known method for producing a fatty acid ester can be used. Examples of such methods include a method in which a compound having 3 to 6 hydroxyl groups in the molecule and a straight-chain fatty acid having 6 to 18 carbon atoms are mixed, optionally with a catalyst, in a solvent or without a solvent, at a temperature of 120°C to 260°C, preferably 180°C to 250°C, more preferably 200°C to 230°C, under pressure, reduced pressure, or normal pressure, and maintained for 10 minutes to 20 hours until the reaction is complete.

[0035] The catalyst that can be used in the production of the fatty acid ester (B) used in the present invention can be a known catalyst. Examples of such catalysts include acidic catalysts such as sulfuric acid, phosphoric acid, zinc chloride, benzenesulfonic acid, p-toluenesulfonic acid, and 4-chlorobenzenesulfonic acid; alkoxytitanium compounds such as tetramethoxytitanium, tetraethoxytitanium, and tetraisopropoxytitanium; titanium acylate compounds such as polyhydroxytitanium stearate and polyisopropoxytitanium stearate; titanium chelate compounds such as titanium acetylacetate, triethanolamine titanate, titanium ammonium lactate, titanium ethyl lactate, and titanium octylene glycolate; tin compounds such as dibutyltin dilaurate, dibutyltin oxide, and dibutyltin diacetate; metal acetates such as magnesium acetate, calcium acetate, and zinc acetate; and metal oxides such as antimony oxide and zirconium oxide. One or more of these can be used.

[0036] 3. Content of polyester (A) and fatty acid ester (B) The lubricating composition of the present invention contains the above-described polyester (A) and fatty acid ester (B), wherein the content of the polyester (A) in the lubricating composition is 10 to 85 mass% and the content of the fatty acid ester (B) in the lubricating composition is 15 to 90 mass% relative to the total amount of the lubricating composition. In the present invention, by containing a specific polyester (A) and a specific fatty acid ester (B) in a specific content ratio, a lubricating composition exhibiting a good friction-reducing effect can be obtained due to the synergistic effect of the polyester (A) and the fatty acid ester (B). In the present invention, from the viewpoint of obtaining a lubricating composition exhibiting a better friction-reducing effect, the content of the polyester (A) is preferably 10 to 70 mass% and the content of the fatty acid ester (B) is 30 to 90 mass%, and more preferably the content of the polyester (A) is 10 to 60 mass% and the content of the fatty acid ester (B) is 40 to 90 mass%, relative to the total amount of the lubricating composition.

[0037] 4. Use of the lubricating composition The use mode of the lubricating composition of the present invention is not particularly limited, and it can be suitably used, for example, in lubricant compositions such as lubricating oil, fuel oil, hydraulic oil, metalworking oil, grease, etc. Among these, from the viewpoint of the effects of the present invention, it is preferably used as a lubricating composition for lubricating oil, hydraulic oil, metalworking oil, or grease, more preferably used as a lubricating composition for hydraulic oil, metalworking oil, or grease, and even more preferably used as a lubricating composition for hydraulic oil or grease.

[0038] B. Lubricant Composition The lubricant composition of the present invention is a lubricant composition containing the above-mentioned lubricating composition. The lubricant composition of the present invention may further contain known base oils and additives depending on the intended use, from the viewpoints of friction characteristics, wear characteristics, oxidation stability, temperature stability, storage stability, detergency, rust prevention, corrosion prevention, handleability, etc.

[0039] 1. Base oil Examples of base oils include mineral base oils, chemically synthesized base oils, and animal and vegetable base oils, and one or more of these can be used. Examples of mineral base oils include distillate oils obtained by atmospheric distillation of paraffinic crude oil, naphthenic crude oil, or intermediate crude oil, or by vacuum distillation of residual oil from atmospheric distillation, and refined oils obtained by refining these oils in accordance with conventional methods, specifically solvent refined oils, hydrogenated refined oils, dewaxed oils, and clay-treated oils.

[0040] Examples of chemically synthesized base oils include poly-α-olefins, polyisobutylene (polybutene), monoesters, diesters, polyol esters, silicate esters, polyalkylene glycols, polyphenyl ethers, silicones, fluorinated compounds, alkylbenzenes, and GTL base oils. Among these, examples of poly-α-olefins include polymers or oligomers of 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, and 1-tetradecene, as well as hydrogenated versions of these. Examples of diesters include diesters of dibasic acids such as glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid with alcohols such as 2-ethylhexanol, octanol, decanol, dodecanol, and tridecanol. Examples of polyol esters include esters of polyols such as neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol with fatty acids such as caproic acid, caprylic acid, lauric acid, capric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, and refined base oils thereof can also be used. Among these, it is preferable to use chemically synthesized base oils such as poly-α-olefins, polyisobutylenes (polybutenes), diesters, and polyol esters, and it is more preferable to use hydrocarbon base oils such as poly-α-olefins.

[0041] Examples of animal and vegetable base oils include vegetable oils such as castor oil, olive oil, cacao butter, sesame oil, rice bran oil, safflower oil, soybean oil, camellia oil, corn oil, rapeseed oil, palm oil, palm kernel oil, sunflower oil, cottonseed oil, and coconut oil, and animal oils such as beef tallow, lard, milk fat, fish oil, and whale oil, and these may be used alone or in combination of two or more. If necessary, highly refined base oils obtained by highly refining these base oils to reduce the amount of impurities such as sulfur may also be used.

[0042] The kinematic viscosity of the base oil that can be used in the present invention is not particularly limited and can be adjusted appropriately depending on the purpose, but for example, a base oil having a kinematic viscosity at 40°C of 1.0 to 600 cSt can be used. From the viewpoint of the friction characteristics and other properties of the resulting lubricant composition, it is preferable to use a base oil having a kinematic viscosity at 40°C of 2.0 to 200 cSt, more preferably 4.0 to 100 cSt, and even more preferably 6.0 to 50 cSt.

[0043] The content of the base oil in the lubricant composition of the present invention is not particularly limited and can be adjusted appropriately depending on the purpose, but can be, for example, 50 to 99.99 mass% based on the total amount of the lubricant composition. When the lubricant composition of the present invention contains two or more base oils, the total content of the base oils is the sum of the respective contents.

[0044] 2. Additives Examples of additives include antioxidants, friction reducers, anti-wear agents, oiliness improvers, detergents, ashless dispersants, viscosity index improvers, rust inhibitors, corrosion inhibitors, metal deactivators, and antifoaming agents, and one or more of these can be used. Examples of antioxidants include 2,6-di-tert-butylphenol (hereinafter, tert-butyl will be abbreviated as t-butyl), 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 4,4'-bis(2-methyl-6-t-butylphenol), 2,2'-methylenebis(4-methyl- 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 4,4'-isopropylidenebis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(4-methyl-6-nonylphenol), 2,2'-isobutylidenebis(4,6-dimethylphenol), 2,6-bis(2'-hydroxy-3'-t-butyl-5'-methylbenzyl) -4-Methylphenol, 3-t-butyl-4-hydroxyanisole, 2-t-butyl-4-hydroxyanisole, octyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, stearyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, oleyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, dodecyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, decyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, tetrahydrofuran Rakis{3-(4-hydroxy-3,5-di-t-butylphenyl)propionyloxymethyl}methane, 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid glycerol monoester, ester of 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid and glycerol monooleyl ether, 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid butylene glycol diester, 3-(4-hydroxy-3,5-di-t-butylphenyl)propionic acid thiodiglycol diester, 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-thiobis(2-methyl-6-t-butylphenol), 2,2'-thiobis(4-methyl-6-t-butylphenol), 2,6-di-t-butyl-α-dimethylamino-p-cresol, 2,6-di-t-butyl-4-(N,N'-dimethylaminomethylphenol), bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide, tris{(3,5-di-t-butyl-4-hydroxyphenyl)propionyl} propionyl-oxyethyl} isocyanurate, tris(3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, bis{2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl}sulfide, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, tetraphthaloyl-di(2,6-dimethylbenzyl)isocyanurate N,N'-Hexamethylenebis(3,5-di-t-butyl-4-hydroxybenzyl phosphate diester), bis(3 -methyl-4-hydroxy-5-t-butylbenzyl) sulfide, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, bis{3,phenolic antioxidants such as 3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid glycol ester; naphthylamine antioxidants such as 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, and phenyl-2-naphthylamine; N,N'-diisopropyl-p-phenylenediamine, N, N'-Diisobutyl-p-phenylenediamine, N,N'-Diphenyl-p-phenylenediamine, N,N'-Di-β-naphthyl-p-phenylenediamine, N-Phenyl-N'-isopropyl-p-phenylenediamine, N-Cyclohexyl-N'-phenyl-p-phenylenediamine, N-1,3-Dimethylbutyl-N'-phenyl-p-phenylenediamine, Dioctyl-p-phenylenediamine, Phenylhexyl-p-phenylenediamine, Phenyl Phenylenediamine-based antioxidants such as octyl-p-phenylenediamine; dipyridylamine, diphenylamine, p,p'-di-n-butyldiphenylamine, p,p'-di-t-butyldiphenylamine, p,p'-di-t-pentyldiphenylamine, p,p'-dioctyldiphenylamine, p,p'-dinonyldiphenylamine, p,p'-didecyldiphenylamine, p,p'-didodecyldiphenylamine, p,p'-distyryldiphenylamine; Examples of antioxidants include diphenylamine-based antioxidants such as phenanthroline, p,p'-dimethoxydiphenylamine, 4,4'-bis(4-α,α-dimethylbenzoyl)diphenylamine, p-isopropoxydiphenylamine, and dipyridylamine; phenothiazine-based antioxidants such as phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazinecarboxylic acid esters, and phenoselenazine; and zinc dithiophosphate. The amount of these antioxidants blended is preferably 0.01 to 5 mass%, and more preferably 0.05 to 4 mass%, based on the total amount of the lubricant composition.

[0045] Examples of friction reducers include organic molybdenum compounds such as molybdenum dithiocarbamate and molybdenum dithiophosphate; ashless friction modifiers such as aliphatic amines, fatty acid esters (excluding the above-mentioned fatty acid ester (B)), fatty acid amides, fatty acids, fatty alcohols, and aliphatic ethers, each having at least one alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule; oils and fats, amines, amides, sulfurized esters, etc. The amount of these friction reducers to be added is preferably 0.01 to 10 mass %, and more preferably 0.05 to 5 mass %, based on the total amount of the lubricant composition.

[0046] Examples of anti-wear agents include sulfurized oils and fats, olefin polysulfides, sulfurized olefins, dibenzyl sulfide, ethyl-3-[[bis(1-methylethoxy)phosphinothioyl]thio]propionate, tris-[(2 or 4)-isoalkylphenol]thiophosphate, 3-(di-isobutoxy-thiophosphorylsulfanyl)-2-methyl-propionic acid, triphenylphosphorothionate, β-dithiophosphorylated propionic acid, methylenebis(dibutyldithiocarbamate), O, Sulfur-based additives such as O-diisopropyl-dithiophosphoryl ethyl propionate, 2,5-bis(n-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(1,1,3,3-tetramethylbutanethio)-1,3,4-thiadiazole, and 2,5-bis(1,1,3,3-tetramethyldithio)-1,3,4-thiadiazole; monooctyl phosphate, dioctyl phosphate, trioctyl phosphate, monobutyl phosphate, dibutyl phosphate, tributyl phosphate phosphorus compounds such as phosphate, monophenyl phosphate, diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, monoisopropyl phenyl phosphate, diisopropyl phenyl phosphate, triisopropyl phenyl phosphate, monotertiary butyl phenyl phosphate, di-tert-butyl phenyl phosphate, tri-tert-butyl phenyl phosphate, triphenyl thiophosphate, monooctyl phosphite, dioctyl phosphite, trioctyl phosphite, monobutyl phosphite, dibutyl phosphite, tributyl phosphite, monophenyl phosphite, diphenyl phosphite, triphenyl phosphite, monoisopropyl phenyl phosphite, diisopropyl phenyl phosphite, triisopropyl phenyl phosphite, mono-tert-butyl phenyl phosphite, di-tert-butyl phenyl phosphite, and tri-tert-butyl phenyl phosphite;Organometallic compounds such as metal dithiophosphates (Zn, Sb, Mo, etc.), metal dithiocarbamates (Zn, Sb, Mo, etc.), metal naphthenates, metal fatty acid salts, metal phosphates, metal phosphate ester salts, and metal phosphite ester salts; and other compounds such as boron compounds, alkylamine salts of mono- and dihexyl phosphates, amine phosphate ester salts, and mixtures of triphenylthiophosphate esters and tert-butylphenyl derivatives. The amount of these antiwear agents blended is preferably 0.01 to 3 mass %, more preferably 0.05 to 2 mass %, based on the total amount of the lubricant composition.

[0047] Examples of oiliness improvers include higher alcohols such as oleyl alcohol and stearyl alcohol; fatty acids such as oleic acid and stearic acid; esters such as oleyl glycerin ester, stearyl glycerin ester, and lauryl glycerin ester; amides such as laurylamide, oleylamide, and stearylamide; amines such as laurylamine, oleylamine, and stearylamine; and ethers such as lauryl glycerin ether and oleyl glycerin ether. The amount of these oiliness improvers to be added is preferably 0.01 to 5% by mass, and more preferably 0.05 to 3% by mass, of the total amount of the lubricant composition.

[0048] Examples of detergents include sulfonates, phenates, salicylates, phosphates, and overbased salts of calcium, magnesium, barium, etc. Among these, detergents with a TBN (total base number) of 30 to 500 mgKOH / g are preferred. The amount of detergent blended is preferably 0.5 to 10 mass% and more preferably 1 to 8 mass% based on the total amount of the lubricant composition. The content of calcium atoms derived from the detergent in the lubricant composition is not particularly limited, but from the viewpoint of detergency, the content of calcium atoms derived from the detergent in the lubricant composition is preferably 100 to 3000 mass ppm and more preferably 200 to 2500 mass ppm. The content of magnesium atoms derived from the detergent in the lubricant composition is not particularly limited, but from the viewpoint of detergency, the content of magnesium atoms derived from the detergent in the lubricant composition is preferably 50 to 2000 mass ppm and more preferably 100 to 1000 mass ppm.

[0049] The ashless dispersant may be any known ashless dispersant used in lubricants, without particular limitation. Examples include nitrogen-containing compounds or derivatives thereof having at least one linear or branched alkyl or alkenyl group having 40 to 400 carbon atoms in the molecule. Specific examples include succinimides, succinamides, succinate esters, succinate ester-amides, benzylamines, polyamines, polysuccinimides, and Mannich bases. Derivatives thereof include those obtained by reacting these nitrogen-containing compounds with boron compounds such as boric acid and borates, phosphorus compounds such as thiophosphoric acid and thiophosphates, organic acids, and hydroxypolyoxyalkylene carbonates. If the alkyl or alkenyl group has fewer than 40 carbon atoms, the solubility of the compound in the base oil may decrease. On the other hand, if the alkyl or alkenyl group has more than 400 carbon atoms, the low-temperature fluidity of the lubricant composition may deteriorate. The amount of these ashless dispersants added is preferably 0.5 to 10 mass %, more preferably 1 to 8 mass %, based on the total amount of the lubricant composition.

[0050] Examples of viscosity index improvers include poly(C1-18) alkyl (meth)acrylate, (C1-18) alkyl acrylate / (C1-18) alkyl (meth)acrylate copolymer, diethylaminoethyl (meth)acrylate / (C1-18) alkyl (meth)acrylate copolymer, ethylene / (C1-18) alkyl (meth)acrylate copolymer, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymer, styrene / maleic acid ester copolymer, and hydrogenated styrene / isoprene copolymer. Alternatively, dispersant-type or multifunctional viscosity index improvers with added dispersant properties may be used. The weight-average molecular weight is approximately 10,000 to 1,500,000. The amount of these viscosity index improvers blended is preferably 0.1 to 20 mass %, more preferably 0.3 to 15 mass %, of the total amount of the lubricant composition.

[0051] Examples of rust inhibitors include sodium nitrite, oxidized paraffin wax calcium salt, oxidized paraffin wax magnesium salt, tallow fatty acid alkali metal salt, alkaline earth metal salt or amine salt, alkenyl succinic acid or alkenyl succinic acid half ester (the molecular weight of the alkenyl group is about 100 to 300), sorbitan monoester, nonylphenol ethoxylate, lanolin fatty acid calcium salt, etc. The amount of these rust inhibitors to be added is preferably 0.01 to 3 mass %, more preferably 0.02 to 2 mass %, based on the total amount of the lubricant composition.

[0052] Examples of corrosion inhibitors and metal deactivators include triazole, tolyltriazole, benzotriazole, benzimidazole, benzothiazole, benzothiadiazole, and derivatives of these compounds, such as 2-hydroxy-N-(1H-1,2,4-triazol-3-yl)benzamide, N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, and 2,2'-[[(4 or 5 or 1)-(2-ethylhexyl)-methyl-1H-benzotriazol-1-methyl]imino]bisethanol, and other bis(poly- Examples of suitable corrosion inhibitors and metal deactivators include 2-carboxyethyl)phosphinic acid, hydroxyphosphonoacetic acid, tetraalkylthiuram disulfide, N'1,N'12-bis(2-hydroxybenzoyl)dodecane dihydrazide, 3-(3,5-di-t-butyl-hydroxyphenyl)-N'-(3-(3,5-di-tert-butyl-hydroxyphenyl)propanoyl)propanehydrazide, esters of tetrapropenylsuccinic acid and 1,2-propanediol, disodium sebacate, (4-nonylphenoxy)acetic acid, alkylamine salts of mono- and dihexyl phosphate, sodium salt of tolyltriazole, and (Z)-N-methyl-N-(1-oxo-9-octadecenyl)glycine. The amount of these corrosion inhibitors and metal deactivators to be added is preferably 0.01 to 3 mass %, more preferably 0.02 to 2 mass %, based on the total amount of the lubricant composition.

[0053] Examples of antifoaming agents include polydimethyl silicone, dimethyl silicone oil, trifluoropropylmethyl silicone, colloidal silica, polyalkyl acrylate, polyalkyl methacrylate, alcohol ethoxy / propoxylate, fatty acid ethoxy / propoxylate, sorbitan partial fatty acid ester, etc. The amount of these antifoaming agents blended is preferably 0.001 to 0.1% by mass, more preferably 0.001 to 0.01% by mass, based on the total amount of the lubricant composition.

[0054] C. Other The present disclosure includes the following aspects.

[0055] [1] A lubricating composition comprising: a polyester (A) obtained by reacting a dibasic acid component having 4 to 12 carbon atoms with one or more glycol components selected from the group consisting of 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, and 1,4-butanediol; a hydroxy acid component including 12-hydroxystearic acid; and one or more end-termining components selected from the group consisting of monovalent fatty acids having 8 to 12 carbon atoms and linear monohydric alcohols having 6 to 10 carbon atoms; and a fatty acid ester (B) which is an ester of a compound having 3 to 6 hydroxyl groups in the molecule with a linear fatty acid having 6 to 18 carbon atoms, wherein the content of the polyester (A) in the lubricating composition is 10 to 85 mass% and the content of the fatty acid ester (B) is 15 to 90 mass% relative to the total amount of the lubricating composition.

[0056] [2] The lubricating composition according to [1], wherein the polyester (A) has a number average molecular weight of 700 to 10,000.

[0057] [3] The lubricating composition according to [1] or [2], wherein the fatty acid ester (B) is an ester of trimethylolpropane and a linear fatty acid having 7 to 10 carbon atoms, or a mixture of an ester of trimethylolpropane and a linear fatty acid having 7 to 10 carbon atoms and an ester of pentaerythritol and a linear fatty acid having 8 to 10 carbon atoms.

[0058] [4] A lubricant composition comprising the lubricating composition according to any one of [1] to [3]. [Example]

[0059] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. In the following production examples, the number average molecular weight of the polyester was measured by the <Method for measuring number average molecular weight> described below, the acid values ​​(mg KOH / g) of the polyester and fatty acid ester were measured by the <Method for measuring acid value> described below, and the hydroxyl values ​​(mg KOH / g) of the polyester and fatty acid ester were measured by the <Method for measuring hydroxyl value> described below.

[0060] <Method for measuring number average molecular weight> Using a sample prepared by dissolving 50 mg of polyester in 10 mL of tetrahydrofuran, the number average molecular weight was measured in terms of polystyrene by the following measurement method. GPC device: HLC-8320GPC (Tosoh Corporation) Column: SHODEX KF-402.5 manufactured by Showa Denko K.K. Detector: RI detector (built into HLC-8320GPC) Flow rate: 0.3ml / min Injection volume: 5μl Column temperature: 40℃ Standard sample: TSKgel standard polystyrene (weight average molecular weight: 98,900, 37,200, 13,700, 9,490, 5,430, 3,120, 1,010, 589, all manufactured by Tosoh Corporation)

[0061] <Acid value measurement method> Polyester or fatty acid ester was weighed to the nearest 10 mg in a container and thoroughly dissolved in a neutral toluene / ethanol solution. A few drops of phenolphthalein indicator were added, and the solution was titrated with a 0.1N KOH aqueous solution.

[0062] <Hydroxyl value measurement method> Polyester or fatty acid ester was weighed to the nearest 10 mg into a container and thoroughly dissolved in 10 mL of triethyl phosphate. 10.85 g of 60% perchloric acid and 18 mL of acetic anhydride were added to 900 mL of triethyl phosphate, mixed, and then 93 mL of acetic anhydride was added to prepare reagent (a), 15 mL of which was added and thoroughly stirred. 20 mL of reagent (d), prepared by mixing pyridine and distilled water in a 3:1 volume ratio, was added and allowed to stand for 5 minutes. 50 mL of neutral isopropyl alcohol was then added, and several drops of phenolphthalein indicator were added. The solution was then titrated with 1.0 N KOH aqueous solution.

[0063] <Production of Polyester A-1> Polyester A-1 was produced by esterifying 40 g of castor oil-derived sebacic acid as the dibasic acid component, 25 g of rapeseed oil-derived 1,2-propylene glycol as the glycol component, 15 g of castor oil-derived 12-hydroxystearic acid as the hydroxy acid component, and 20 g of coconut oil-derived n-octanoic acid as the end-terminator using dibutyltin oxide as a catalyst at 200 to 230°C. The resulting polyester A-1 had a number average molecular weight of 1,970, an acid value of 0.40 mgKOH / g, and a hydroxyl value of 10.6 mgKOH / g.

[0064] <Production of fatty acid ester B-1> A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 473 g (3.52 mol) of trimethylolpropane and, as straight-chain fatty acids, 22 g (0.17 mol) of n-heptanoic acid, 1680 g (11.63 mol) of n-octanoic acid, and 60 g (0.35 mol) of n-decanoic acid. The mixture was heated to dissolve uniformly, and then an esterification reaction was carried out at 220-230°C for 10 hours while removing the distilled water. Subsequently, unreacted straight-chain fatty acid was removed under reduced pressure to produce fatty acid ester B-1. The obtained fatty acid ester B-1 was a mixed triester of trimethylolpropane with n-heptanoic acid, n-octanoic acid, and n-decanoic acid (n-heptanoic acid=1.4 mol %, n-octanoic acid=95.7 mol %, n-decanoic acid=2.9 mol %), and was a fatty acid ester with an acid value of 0.05 mg KOH / g and a hydroxyl value of 1.3 mg KOH / g.

[0065] <Production of fatty acid ester B-2> A flask equipped with a stirrer, thermometer, nitrogen tube, and reflux condenser was charged with 380 g (2.78 mol) of pentaerythritol and 1740 g (12.06 mol) of n-octanoic acid and 126 g (0.731 mol) of n-decanoic acid as linear fatty acids. The mixture was heated to dissolve uniformly, and then esterification reaction was carried out at 220-230 °C for 10 hours while removing distilled water. Subsequently, unreacted linear fatty acids were removed under reduced pressure to produce fatty acid ester B-2. The obtained fatty acid ester B-2 was a mixed tetraester of pentaerythritol with n-octanoic acid and n-decanoic acid (n-octanoic acid = 94.3 mol%, n-decanoic acid = 5.7 mol%), and had an acid value of 0.03 mg KOH / g and a hydroxyl value of 1.6 mg KOH / g.

[0066] <Fatty acid ester B'-3> The fatty acid ester B'-3 used was tris(2-ethylhexanoate)trimethylolpropane manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. The fatty acid ester B'-3 was a triester of trimethylolpropane and 2-ethylhexanoic acid (branched fatty acid), and had an acid value of 0.03 mg KOH / g and a hydroxyl value of 0.6 mg KOH / g.

[0067] <Examples 1 to 8 and Comparative Examples 1 to 10> The produced polyesters and fatty acid esters were mixed in the amounts shown in Tables 1 to 4 to prepare lubricating compositions of Examples 1 to 8 and Comparative Examples 1 to 10. In Tables 1 to 4, % represents mass %.

[0068] <Friction characteristic evaluation> The coefficient of friction of each of the prepared lubricating compositions of Examples 1 to 8 and Comparative Examples 1 to 10 was measured using an MTM testing machine manufactured by PCS Instruments under the following test conditions. The friction properties were evaluated based on the measured friction coefficients and the following evaluation criteria for friction properties. The evaluation results are shown in Tables 1 to 4, respectively. In this evaluation, if the evaluation result for friction properties was ⊚ or ○, it indicated that the lubricating composition had practical friction properties.

[0069] Test conditions Load: 36N Rolling speed: 300mm / s Slip rate: 50% Test temperature: 40℃

[0070] Evaluation criteria for friction characteristics ◎: Friction coefficient less than 0.038 ○: Friction coefficient is 0.038 or more and less than 0.040 ×: Friction coefficient is 0.040 or more

[0071] [Table 1]

[0072] [Table 2]

[0073] [Table 3]

[0074] [Table 4]

[0075] From the above results, it can be seen that the lubricating composition of the present invention exhibits a good friction reducing effect.

Claims

1. a polyester (A) obtained by reacting a dibasic acid component having 4 to 12 carbon atoms with one or more glycol components selected from the group consisting of 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, and 1,4-butanediol, a hydroxy acid component containing 12-hydroxystearic acid, and one or more end-stopping components selected from the group consisting of monovalent fatty acids having 8 to 12 carbon atoms and linear monohydric alcohols having 6 to 10 carbon atoms; A lubricating composition comprising a fatty acid ester (B) which is an ester of a compound having 3 to 6 hydroxyl groups in the molecule and a linear fatty acid having 6 to 18 carbon atoms, A lubricating composition, wherein the content of the polyester (A) is 10 to 85 mass % and the content of the fatty acid ester (B) is 15 to 90 mass % relative to the total amount of the lubricating composition.

2. 2. The lubricating composition according to claim 1, wherein the polyester (A) has a number average molecular weight of 700 to 10,000.

3. 2. The lubricating composition according to claim 1, wherein the fatty acid ester (B) comprises an ester of trimethylolpropane and a linear fatty acid having 7 to 10 carbon atoms, or a mixture of an ester of trimethylolpropane and a linear fatty acid having 7 to 10 carbon atoms and an ester of pentaerythritol and a linear fatty acid having 8 to 10 carbon atoms.

4. A lubricant composition comprising the lubricating composition of claim 1.

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