Water-soluble lubricant

Abstract

To provide a water-soluble lubricant excellent in biodegradability, rust prevention performance, and suppression of metal elution.SOLUTION: A water-soluble lubricant comprises a compound (A) represented by the following general formula (1): R1-[-O-(A1O)j-R2]k, and an amine compound (B) represented by the following general formula (2): N(Q)(3-m)-[(A2O)nH]m, and a hydroxy acid (C). The number-average molecular weight of the (A) contained in the water-soluble lubricant is less than 2,000. Based on the total weight of the water-soluble lubricant, the weight ratio of the compound (A) is 85 to 99.7 wt.%, the weight ratio of the amine compound (B) is 0.1 to 10 wt.%, and the weight ratio of the hydroxy acid (C) is 0.2 to 5 wt.%. The molar ratio [OH derived from hydroxy acid (C) / OH derived from amine (B)] between hydroxyl groups derived from the amine compound (B) and hydroxyl groups derived from the hydroxy acid (C) is 0.03 to 0.4.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-soluble lubricant. [Background technology]

[0002] Conventionally, as lubricating oil base oils for hydraulic oils, gear oils, bearing oils, etc., mineral oils, hydrocarbon-based base oils such as polyolefins, or polyethers such as alkylene oxide adducts of alcohols, have been used. In recent years, as awareness of environmental issues has increased, lubricating oils have also come to be required to be biodegradable, but the above-mentioned hydrocarbon-based base oils and polyether-based base oils have a problem of insufficient biodegradability. From the viewpoint of biodegradability, natural fats and oils such as vegetable oils and their derivatives, synthetic ester-based lubricating oil base oils, etc. have been used as lubricating oil base oils (see, for example, Patent Documents 1-2). However, natural oils and fats and their derivatives, as well as synthetic ester-based lubricating base oils, are prone to hydrolysis when water is mixed in, and have stability problems during use. In addition, since these base oils have low solubility in water, when the lubricating oil leaks, it forms oil droplets on the water surface, causing significant contamination of the surrounding area and making it difficult to clean and remove. Therefore, from the viewpoints of solubility in water and biodegradability, the use of polyether-based base oils has been considered (see Patent Document 3). In addition, since December 2013, US regulations have been amended to require the use of Environmentally Acceptable Lubricants (EAL) products on all vessels operating in US waters. Under these circumstances, particularly for marine gear oils, very specific specifications must be met with regard to tribological performance and bearing compatibility (metal elution suppression). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 05-331481 [Patent Document 2] Japanese Patent Application Publication No. 11-323373 [Patent Document 3] JP 2006-083378 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a water-soluble lubricant which is excellent in biodegradability and rust prevention performance, and which is also excellent in inhibiting metal elution. [Means for solving the problem]

[0005] The present inventors conducted extensive research to solve the above problems and arrived at the present invention. That is, the present invention is as follows. [1] A water-soluble lubricant comprising a compound (A) represented by the following general formula (1), an amine compound (B) represented by the following general formula (2), and a hydroxy acid (C), wherein the number average molecular weight of the compound (A) contained in the water-soluble lubricant is less than 2000, the weight ratio of the compound (A) is 85 to 99.7% by weight, the weight ratio of the amine compound (B) is 0.1 to 10% by weight, and the weight ratio of the hydroxy acid (C) is 0.2 to 5% by weight, based on the total weight of the water-soluble lubricant, and the molar ratio of the hydroxyl groups derived from the amine compound (B) to the hydroxyl groups derived from the hydroxy acid (C) [hydroxyl groups derived from the hydroxy acid (C) / hydroxyl groups derived from the amine compound (B)] is 0.03 to 0.4. R 1 -[-O-(A 1 O) j -R 2 ] k (1) [In formula (1), R 1 is a hydrogen atom or a k-valent hydrocarbon group having 1 to 12 carbon atoms, k is an integer of 1 to 6, 1 Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, j is an integer of 1 or more representing the number of moles of the alkyleneoxy group added, and R 2 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms.] N(Q) (3-m) -[(A 2 O)n H] m (2) [In formula (2), A 2 Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, n is an integer of 1 to 20, and when n is 2 or more, A 2 O may be the same or different, m is an integer of 1 to 3, and when m is 2 or more, there are multiple [(A 2 O) n H] may be the same or different, and each Q independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 24 carbon atoms. [2] The water-soluble lubricant according to [1], comprising, as the amine compound (B), an amine in which m is 2 and Q is an aliphatic hydrocarbon group having 1 to 24 carbon atoms in general formula (2), and a compound in which m is 1 to 2 and Q is a hydrogen atom in general formula (2), or an amine in which m is 3. [3] The water-soluble lubricant according to [1] or [2], wherein the compound (A) is a compound in which k in general formula (1) is an integer of 1 to 3. [4] The compound (A) is represented by the general formula (1), 1 The water-soluble lubricant according to any one of [1] to [3], which is a compound having only an ethyleneoxy group as O and / or a compound having an ethyleneoxy group and a propyleneoxy group. [5] The water-soluble lubricant according to [4], wherein the ratio (EO / PO) of the number of moles of propyleneoxy groups (PO) to the number of moles of ethyleneoxy groups (EO) constituting the compound (A) contained in the water-soluble lubricant is 100 / 0 to 50 / 50. [6] The water-soluble lubricant according to any one of [1] to [5], wherein the hydroxy acid (C) is at least one selected from the group consisting of lactic acid, malic acid, citric acid and tartaric acid. [7] The water-soluble lubricant according to any one of [1] to [6], further comprising a phosphorus compound (D). [8] The water-soluble lubricant according to [7], wherein the phosphorus compound (D) is at least one selected from the group consisting of phosphates, acid phosphates, thiophosphates, amine salts of acid phosphates, and phosphites. [9] The water-soluble lubricant according to any one of [1] to [8], wherein the compound (A) has a biodegradability of 60% or more.

[10] The water-soluble lubricant has a kinetic viscosity of 10 to 150 mm at 40 ° C. 2 The water-soluble lubricant according to any one of [1] to [9] above,

[11] The water-soluble lubricant according to any one of [1] to

[10] , which is a bearing oil, hydraulic oil, or gear oil for ships. Effect of the Invention

[0006] The water-soluble lubricant of the present invention exhibits the effects of being excellent in biodegradability and rust prevention performance, and in suppressing metal elution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The water-soluble lubricant of the present invention comprises a compound (A) represented by the following general formula (1), an amine compound (B) represented by the following general formula (2), and a hydroxy acid (C), wherein the number average molecular weight of the compound (A) contained in the water-soluble lubricant is less than 2000, the compound (A) accounts for 85 to 99.7% by weight, the amine compound (B) accounts for 0.1 to 10% by weight, and the hydroxy acid (C) accounts for 0.2 to 5% by weight, based on the total weight of the water-soluble lubricant, and the molar ratio of the hydroxyl groups derived from the amine compound (B) to the hydroxyl groups derived from the hydroxy acid (C) [hydroxyl groups derived from the hydroxy acid (C) / hydroxyl groups derived from the amine compound (B)] is 0.03 to 0.4. R 1 -[-O-(A 1 O) j -R 2 ] k (1) [In formula (1), R 1 is a hydrogen atom or a k-valent hydrocarbon group having 1 to 12 carbon atoms, k is an integer of 1 to 6, 1 Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, j is an integer of 1 or more representing the number of moles of the alkyleneoxy group added, and R 2each independently represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms.] N(Q) (3-m) -[(A 2 O) n H] m (2) [In formula (2), A 2 Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, n is an integer of 1 to 20, and when n is 2 or more, A 2 O may be the same or different, m is an integer of 1 to 3, and when m is 2 or more, there are multiple [(A 2 O) n H] may be the same or different, and each Q independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 24 carbon atoms. In the present invention, water-soluble refers to a substance whose solubility in water at 25° C. is 20 g or more per 100 g of water.

[0008] <Compound (A)> In the present invention, the compound (A) is a compound represented by the above general formula (1). The number average molecular weight of the compound (A) contained in the water-soluble lubricant is less than 2000, and from the viewpoints of biodegradability and compatibility with (B) and (C), it is preferably 400 or more, and more preferably 600 or more. One type of compound (A) may be used, or two or more types may be used in combination. When two or more types of compound (A) are used in combination, the number average molecular weight of the two or more compounds may be less than 2000. When two or more types of compounds are used in combination, each of the two or more compounds may be less than 2000 in number average molecular weight, or a part of the two or more compounds may have a number average molecular weight of 2000 or more.

[0009] In the present invention, the number average molecular weight (hereinafter abbreviated as Mn) is measured by gel permeation chromatography at 40° C. using polypropylene glycol as a standard substance. Device body: HLC-8120 (manufactured by Tosoh Corporation) Column: Tosoh Corporation TSKgel α6000, G3000 PWXL Detector: Differential refractometer detector built into the device body Eluent: 0.5% sodium acetate / water / methanol (volume ratio 70 / 30) Eluent flow rate: 1.0ml / min Column temperature: 40℃ Sample: 0.25% by weight eluent solution Injection volume: 200μl Standard material: TSK STANDARD OXIDE manufactured by Tosoh Corporation Data processing software: GPC-8020modelII (Tosoh Corporation)

[0010] In the general formula (1), R 1 R is a hydrogen atom or a k-valent hydrocarbon group having 1 to 12 carbon atoms, where k is an integer of 1 to 6. 1 When is a hydrogen atom, k is 1. From the viewpoint of biodegradability, k is preferably an integer of 1 to 3. R 1 From the viewpoint of biodegradability, a hydrogen atom or a monovalent to trivalent hydrocarbon group having 1 to 8 carbon atoms is preferable, and a hydrogen atom or a monovalent to trivalent hydrocarbon group having 1 to 4 carbon atoms is more preferable. Examples of the k-valent hydrocarbon group having 1 to 12 carbon atoms include residues obtained by removing all hydroxyl groups from a compound (A1) having 1 to 6 hydroxyl groups and having 1 to 12 carbon atoms. Examples of the compound (A1) having 1 to 12 carbon atoms and 1 to 6 hydroxyl groups include a compound (A11) having 1 to 12 carbon atoms and 1 hydroxyl group, a compound (A12) having 2 to 12 carbon atoms and 2 hydroxyl groups, a compound (A13) having 1 to 12 carbon atoms and 3 hydroxyl groups, a compound (A14) having 1 to 12 carbon atoms and 4 hydroxyl groups, a compound (A15) having 2 to 12 carbon atoms and 5 hydroxyl groups, and a compound (A16) having 2 to 12 carbon atoms and 6 hydroxyl groups.

[0011] Examples of the compound (A11) having 1 to 12 carbon atoms and one hydroxyl group include chain aliphatic monoalcohols having 1 to 12 carbon atoms (e.g., methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, 2-pentanol, 3-pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, etc.). Examples of the compound (A12) having 1 to 12 carbon atoms and two hydroxyl groups include chain aliphatic diols having 1 to 12 carbon atoms (e.g., dihydroxymethyl, ethylene glycol, 1,2- or 1,3-propylene glycol, butanediol, hexanediol, methylpentanediol, neopentyl glycol, etc.), alicyclic diols having 6 to 12 carbon atoms (e.g., bis(hydroxymethyl)cyclohexane, etc.), and aromatic ring-containing diols having 6 to 12 carbon atoms (e.g., bis(hydroxyethyl)benzene, etc.). Examples of the compound (A13) having 1 to 12 carbon atoms and 3 hydroxyl groups include glycerin and trimethylolpropane. Examples of the compound (A14) having 1 to 12 carbon atoms and 4 hydroxyl groups include tetritols (such as erythritol) and pentaerythritol. Examples of the compound (A15) having 2 to 12 carbon atoms and 5 hydroxyl groups include pentitols (eg, adonitol, etc.). Examples of the compound (A16) having 6 hydroxyl groups and having 2 to 12 carbon atoms include hexitols (such as sorbitol, etc.). From the viewpoint of biodegradability, the compound (A1) having 1 to 12 carbon atoms and 1 to 6 hydroxyl groups is preferably a compound having 1 to 12 carbon atoms and 1 to 3 hydroxyl groups (more preferably an aliphatic compound), and further preferably a compound having 1 to 12 carbon atoms and 1 to 2 hydroxyl groups (more preferably an aliphatic compound).

[0012] In the general formula (1), A 1are each independently an alkylene group having 2 to 4 carbon atoms, and examples of such groups include an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3-, or 1,4-butylene group. 1 Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, and examples of the alkyleneoxy group include an ethyleneoxy group, a propyleneoxy group, and a butyleneoxy group. Among these, from the viewpoint of biodegradability, an ethyleneoxy group and a propyleneoxy group are preferred. In the general formula (1), j is an integer of 1 or more that represents the number of moles of alkyleneoxy groups added. In the compound (A) contained in the water-soluble lubricant, j (the number of moles of alkyleneoxy groups added) per molecule of compound (A) is preferably 5 to 44, and more preferably 6 to 44, from the viewpoint of lubricity.

[0013] In the general formula (1), R 2 are each independently a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. Examples of the hydrocarbon group having 1 to 8 carbon atoms include chain aliphatic hydrocarbon groups having 1 to 8 carbon atoms (e.g., methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, etc.). R 2 From the viewpoint of biodegradability, a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms (more preferably a chain aliphatic hydrocarbon group) is preferred, and a hydrogen atom is even more preferred.

[0014] The compound (A) preferably includes a compound in which k in general formula (1) is an integer of 1 to 3. Specific preferred examples of the compound (A) include the following. (1)R 1 is a monovalent chain aliphatic hydrocarbon group having 1 to 12 carbon atoms, and R 2 is a hydrogen atom For example, the above-mentioned alkylene oxide (hereinafter, alkylene oxide and alkyleneoxy group may be abbreviated as AO) adduct having 2 to 4 carbon atoms of the chain aliphatic monoalcohol having 1 to 12 carbon atoms {for example, an ethylene oxide (hereinafter, ethylene oxide and ethyleneoxy group may be abbreviated as EO) (1 to 40 moles) adduct of the above-mentioned chain aliphatic monoalcohol having 1 to 12 carbon atoms, a 1,2-propylene oxide (hereinafter, 1,2-propylene oxide and propyleneoxy group may be abbreviated as PO) (1 to EO (1 to 40 mol) PO (1 to 30 mol) adduct of the chain aliphatic monoalcohol having 1 to 12 carbon atoms, 1,2-butylene oxide (hereinafter, 1,2-butylene oxide and butyleneoxy group may be abbreviated as BO) (1 to 25 mol) adduct of the chain aliphatic monoalcohol having 1 to 12 carbon atoms, EO (1 to 40 mol) BO (1 to 25 mol) adduct of the chain aliphatic monoalcohol having 1 to 12 carbon atoms, tetrahydrofuran (hereinafter, may be abbreviated as THF) (2 to 25 mol) adduct of the chain aliphatic monoalcohol having 1 to 12 carbon atoms, etc.;

[0015] (2)R 1 is a divalent chain aliphatic hydrocarbon group having 1 to 12 carbon atoms, and R 2 is a hydrogen atom For example, an AO adduct having 2 to 4 carbon atoms of the chain aliphatic diol having 1 to 12 carbon atoms {for example, an EO (2 to 40 mol) adduct of the chain aliphatic diol having 1 to 12 carbon atoms, a PO (2 to 30 mol) adduct of the chain aliphatic diol having 1 to 12 carbon atoms, an EO (2 to 40 mol) PO (2 to 30 mol) adduct of the chain aliphatic diol having 1 to 12 carbon atoms, a BO (2 to 25 mol) adduct of the chain aliphatic diol having 1 to 12 carbon atoms, an EO (1 to 40 mol) BO (1 to 25 mol) adduct of the chain aliphatic diol having 1 to 12 carbon atoms, a THF (2 to 25 mol) adduct of the chain aliphatic diol having 1 to 12 carbon atoms, etc.}, etc.;

[0016] (3)R 1 is a trivalent chain aliphatic hydrocarbon group having 1 to 12 carbon atoms, and R2 is a hydrogen atom For example, EO (3-40 mol) adduct of glycerin, PO (3-30 mol) adduct of glycerin, EOPO (total 3-30 mol) adduct of glycerin, BO (3-25 mol) adduct of glycerin, EOBO adduct of glycerin (total 3-25 mol), EO (3-40 mol) adduct of trimethylolpropane, PO (3-30 mol) adduct of trimethylolpropane, EOPO (total 3-30 mol) adduct of trimethylolpropane, BO (3-25 mol) adduct of trimethylolpropane, EOBO adduct of trimethylolpropane (total 3-25 mol), etc.;

[0017] As the compound (A), in the above general formula (1), A 1 Compounds having only ethyleneoxy groups (EO) as O and / or compounds having ethyleneoxy groups (EO) and propyleneoxy groups (PO) are preferred. The ratio of the number of moles of EO to the number of moles of PO constituting the compound (A) contained in the water-soluble lubricant (EO / PO) is preferably 100 / 0 to 50 / 50, more preferably 90 / 10 to 50 / 50, from the viewpoints of biodegradability and load-bearing property.

[0018] The hydroxyl value of the compound (A) is preferably from 28 to 280 mgKOH / g, more preferably from 28 to 190 mgKOH / g, from the viewpoints of biodegradability and solubility in (B). The hydroxyl value can be measured in accordance with JIS K0070.

[0019] The compound (A) preferably has a biodegradability (in accordance with OECD test method 301F) of 60% or more, more preferably 70% or more, and particularly preferably 80% or more. In the present invention, the degree of biodegradation can be measured by the method of OECD301F. For example, the degree of biodegradability tends to be increased by increasing the molar ratio of EO, and tends to be decreased by increasing the molar ratio of PO. For example, the degree of biodegradability tends to increase as the molecular weight decreases, and tends to decrease as the molecular weight increases. Also, R 1 The lower the valence (for example, the number of hydroxyl groups in compound (A1) when compound (A) is produced), the higher the value can be, and the higher the valence, the lower the value tends to be. Specific examples of the compound (A) having a high biodegradability include ethylene glycol (biodegradability: 100%), 1,2-propylene glycol (biodegradability: 90 to 99%), and polyethylene glycol having a degree of polymerization of 4 to 22 (biodegradability: 60 to 70%).

[0020] Examples of the compound (A) that can be used from the viewpoint of biodegradability include polyethylene glycol, an EO adduct of methanol, an EO adduct of ethanol, an EO adduct of propanol, an EO adduct of butanol, an EO adduct of glycerin, an EO adduct of trimethylolpropane, an EO adduct of pentaerythritol, an EO adduct of sorbitol, an EO / PO adduct of methanol, an EO / PO adduct of ethanol, an EO / PO adduct of propanol, an EO / PO adduct of butanol, an EO / PO adduct of hexanol, an EO / PO adduct of octanol, an EO / PO adduct of 1,6-hexylene glycol, diethyl ether, and the like. An EO / PO adduct of ethylene glycol, an EO / PO adduct of glycerin, an EO / PO adduct of trimethylolpropane, an EO / PO adduct of pentaerythritol, or an EO / PO adduct of sorbitol is preferred, and an EO / PO adduct of polyethylene glycol, an EO adduct of methanol, an EO adduct of ethanol, an EO adduct of propanol, an EO adduct of butanol, an EO adduct of glycerin, an EO / PO adduct of methanol, an EO / PO adduct of ethanol, an EO / PO adduct of propanol, an EO / PO adduct of butanol, or an EO / PO adduct of diethylene glycol is more preferred. In the present invention, the compound (A) may be used alone or in combination of two or more kinds.

[0021] Compound (A) can be produced by a known method, for example, by adding an alkylene oxide to compound (A1) having 1 to 6 hydroxyl groups and 1 to 12 carbon atoms, by a known method.

[0022] <Amine Compound (B)> In the present invention, the amine compound (B) is a compound represented by the following general formula (2). In the present invention, the amine compound (B) is "-(A 2 O) n The inclusion of a group represented by "H" improves water solubility and adsorption orientation to metals, providing sufficient rust prevention even with a small amount added. In the present invention, the amine compound (B) may be used alone or in combination of two or more kinds. N(Q) (3-m) -[(A 2 O) n H] m (2) [In formula (2), A 2 Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, n is an integer of 1 to 20, and when n is 2 or more, A 2 O may be the same or different, m is an integer of 1 to 3, and when m is 2 or more, there are multiple [(A 2 O) n H] may be the same or different, and each Q independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 24 carbon atoms.

[0023] In the general formula (2), A 2 represents an alkylene group having 2 to 4 carbon atoms, and examples of such groups include an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3-, or 1,4-butylene group. 2 Specifically, each of O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, and examples of the alkyleneoxy group include an ethyleneoxy group, a propyleneoxy group, and a butyleneoxy group. Among these, from the viewpoint of water solubility, an ethyleneoxy group and a propyleneoxy group are preferred, and an ethyleneoxy group is more preferred.

[0024] In the general formula (2), n is an integer of 1 to 20, and from the viewpoint of rust prevention, 1 to 10 is preferable, and 1 to 2 is more preferable. In addition, when n is 2 or more, there are multiple A 2 O may be the same or different.

[0025] In the general formula (2), m is an integer of 1 to 3, and preferably 2 to 3 from the viewpoint of water solubility. In addition, when m is 2 or more, there are multiple [(A 2 O) n H] may be the same or different.

[0026] In formula (2), each Q independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 24 carbon atoms. Examples of the aliphatic hydrocarbon group having 1 to 24 carbon atoms include linear alkyl groups (e.g., methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, and n-nonadecyl groups). , n-ethylhexyl, etc.), branched alkyl groups (e.g., iso-propyl, iso-, sec- or tert-butyl, iso-pentyl, iso-hexyl, iso-heptyl, iso-octyl, 2-ethylhexyl, iso-nonyl, iso-decyl, iso-undecyl, iso-dodecyl, iso-tridecyl, iso-tetradecyl, iso-pentadecyl, iso-hexadecyl, i so-heptadecyl group, iso-octadecyl group, iso-nonadecyl group, iso-icosyl group, etc.), chain unsaturated hydrocarbon groups {for example, ethylene group, linear or branched alkenyl groups (propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclopropyl, methylcyclohexyl, propylcyclohexyl, etc.}; and unsaturated aliphatic hydrocarbon groups having an alicyclic skeleton {for example, cyclopropenyl, cyclobutenyl, cyclopentenyl, cyclohexenyl, etc.}. From the viewpoint of rust prevention, the aliphatic hydrocarbon group having 1 to 24 carbon atoms is preferably a saturated aliphatic hydrocarbon group having an alicyclic skeleton having 6 to 12 carbon atoms, and more preferably a cyclohexyl group.

[0027] Examples of the amine compound (B) include the following compounds. Compounds where m=1; for example, ethanolamine, propanolamine, butanolamine, N-cyclohexylethanolamine, N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, N-pentylethanolamine, N-hexylethanolamine, N-heptylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dipropylethanolamine, N,N-dialkylamine adducts with 2 to 20 moles of EO, N,N-dialkylamine adducts with 2 to 8 moles of PO, N,N-dialkylamine adducts with 2 to 8 moles of butylene oxide (hereinafter sometimes abbreviated as BO), N,N-dialkylamine adducts with a total of 2 to 20 moles of EO and PO, etc. Compounds where m=2; for example, diethanolamine, dipropanolamine, dibutanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine, N-pentyldiethanolamine, N-hexyldiethanolamine, N-cyclohexyldiethanolamine (cyclohexylamine EO 2 mole adduct), alkylamine EO 3-20 mole adduct, alkylamine PO 3-8 mole adduct, alkylamine BO 3-8 mole adduct, alkylamine EOPO total 3-20 mole adduct, cyclohexylamine EO 3-20 mole adduct, etc. Compounds where m=3; for example, triethanolamine, tripropanolamine, tributanolamine, ammonia adducts with 4 to 20 moles of EO, ammonia adducts with 4 to 8 moles of PO, ammonia adducts with 4 to 8 moles of BO, ammonia adducts with 4 to 20 moles of EOPO in total, etc.

[0028] As the amine compound (B), from the viewpoints of rust prevention and water solubility, monoethanolamine, diethanolamine, triethanolamine, N-cyclohexyldiethanolamine (cyclohexylamine EO 2 moles adduct), and N-cyclohexyldipropanolamine (cyclohexylamine PO 2 moles adduct) are preferred, and triethanolamine and N-cyclohexyldiethanolamine (cyclohexylamine EO 2 moles adduct) are more preferred.

[0029] From the viewpoints of antifouling properties, water solubility and metal elution, the amine compound (B) preferably includes an amine in which, in general formula (2), m is 2 and Q is a hydrocarbon group having 1 to 24 carbon atoms, an amine in which m is 1 to 2 and Q is a hydrogen atom or an amine in which m is 3, more preferably an amine in general formula (2) in which m is 2 and Q is a saturated aliphatic hydrocarbon group having an alicyclic skeleton having 6 to 12 carbon atoms, and an amine in which m is 3, and particularly preferably N-cyclohexyldiethanolamine and / or N-cyclohexyldipropanolamine and triethanolamine.

[0030] The solubility parameter (hereinafter abbreviated as SP value) of the amine compound (B) is 11 to 16 (cal / cm) from the viewpoints of rust prevention, water solubility, and metal elution. 3 ) 1 / 2 is preferable, and more preferably 12 to 16 (cal / cm 3 ) 1 / 2 It is. The SP value in the present invention means a value calculated by the Fedors method, that is, a value calculated by the formula (28) (page 153) using the values ​​(heat of vaporization and molar volume at 25°C of atoms or functional groups) described on page 152 (Table. 5) of Polymer Engineering and Science, February, 1974, Vol. 14, No. 2, pp. 147-154. Specifically, the Δe i and Δv iIt can be calculated by applying the values ​​corresponding to the types of atoms and atomic groups in the molecular structure to the following formula. SP value = (ΣΔe i / ΣΔv i ) 1 / 2

[0031] [Table 1]

[0032] For example, in the case of triethanolamine, it is calculated as follows: N(CH2-CH2-OH)3 SP value = [{1000 + (1180 x 2 + 7120) x 3} / {-9.0 + (16.1 x 2 + 10.0) x 3}] 1 / 2 =15.822(cal / cm 3 ) 1 / 2 For example, the calculation for the 2 mole EO adduct of cyclohexylamine is as follows: ring(CH2)6-N-(CH2-CH2-OH)2 SP value = {(1180 x 5 + 820 + 250) + 1000 + (1180 x 2 + 7120) x 2} / {(16.1 x 5 - 1.0 + 16) - 9.0 + (16.1 x 2 + 10.0) x 2} 1 / 2 =12.553(cal / cm 3 ) 1 / 2

[0033] <Hydroxy acid (C)> In the present invention, the hydroxy acid (C) is a compound having a hydroxy group and a carboxyl group. The hydroxy acid (C) has a carboxyl group, which suppresses the increase in pH caused by the inclusion of the amine compound (B), and has a hydroxyl group, which provides an excellent effect of suppressing metal elution. In the hydroxy acid, the number of hydroxyl groups in one molecule is preferably 1 to 2 from the viewpoint of the metal elution suppression effect. In the hydroxy acid, the number of carboxyl groups in one molecule is preferably 1 to 3 from the viewpoint of ease of pH adjustment. Examples of the hydroxy acid (C) include compounds having 2 to 20 carbon atoms, and specific examples thereof include aliphatic hydroxy acids {e.g., glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citric acid, isocitric acid, mevalonic acid, pantoic acid, ricinoleic acid, quinic acid, shikimic acid, etc.} and aromatic hydroxy acids {e.g., salicylic acid, vanillic acid, syringic acid, etc.}. From the viewpoint of biodegradability, the hydroxy acid (C) is preferably an aliphatic hydroxy acid, more preferably an aliphatic hydroxy acid having 2 to 6 carbon atoms, and particularly preferably lactic acid, malic acid, citric acid, and tartaric acid. In the present invention, the hydroxy acid (C) may be used alone or in combination of two or more kinds.

[0034] <Phosphorus Compounds (D)> The water-soluble lubricant of the present invention may further contain a phosphorus compound (D) in addition to the compound (A), the amine compound (B) and the hydroxy acid (C). The phosphorus compound (D) includes those generally used as extreme pressure agents in lubricants, such as phosphate esters, acidic phosphate esters, amine salts of acidic phosphate esters, phosphites, thiophosphate esters, acidic thiophosphate esters, amine salts of acidic thiophosphate esters, and thiophosphites. Although a wide variety of compounds are known that can impart wear resistance, in the present invention, it is preferable to use the phosphorus compound (D) since it can impart wear resistance without affecting the rust prevention performance and metal elution suppression effect. As the phosphorus compound (D), one type may be used, or two or more types may be used in combination.

[0035] The phosphate esters include those having a hydrocarbon group having 1 to 24 carbon atoms (such as an aryl group, an alkyl group, an alkyl group and an alkenyl group whose carbon chain may be partially substituted with an amide bond or an ester bond), such as triaryl phosphate, trialkyl phosphate, trialkenyl phosphate, dialkylaryl phosphate, and diarylalkyl phosphate. Examples of the aryl group include a phenyl group, an alkyl-substituted phenyl group substituted with an alkyl group having 1 to 18 carbon atoms, and a benzyl group. The alkyl group includes those having 1 to 24 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group. Alkyl groups in which a portion of the carbon chain may be substituted with an amide bond or an ester bond include those having 2 to 24 carbon atoms, such as -CH2CH2-COO-CH3, -CH(COOCH2CH2CH2CH3)(CH2COOCH2CH2CH2CH3), -CH2CONHCH2CH2CH3, and the like. Alkenyl groups include those having 2 to 24 carbon atoms, and examples thereof include linear or branched propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, and octadecenyl groups. Specific examples of triaryl phosphate include triphenyl phosphate, tricresyl phosphate, benzyl diphenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, ethyl phenyl diphenyl phosphate, di(ethylphenyl)phenyl phosphate, propyl phenyl diphenyl phosphate, di(propylphenyl)phenyl phosphate, triethyl phenyl phosphate, tripropyl phenyl phosphate, tert-butyl phenyl diphenyl phosphate, di(tert-butylphenyl)phenyl phosphate, tritert-butyl phenyl phosphate, etc. As the triaryl phosphate, it is preferable that at least one of the three aryl groups is an alkyl-substituted phenyl group substituted with an alkyl group having 1 to 18 carbon atoms. Specific examples of trialkyl phosphates include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, trihexyl phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tristearyl phosphate, and triisooctyl phosphate. The trialkenyl phosphates include tripalmitoleyl phosphate, trioleyl phosphate, and the like. The dialkylaryl phosphates include diethylphenyl phosphate, dibutylphenyl phosphate, and the like. Diaryl alkyl phosphates include diphenyl ethyl phosphate and the like. From the viewpoints of abrasion resistance and solubility, the phosphate ester is preferably a phosphate ester having a hydrocarbon group having 2 to 24 carbon atoms, more preferably a phosphate ester having a hydrocarbon group having 8 to 18 carbon atoms. Furthermore, from the viewpoints of abrasion resistance and solubility, the hydrocarbon group is preferably an alkyl group or an alkyl-substituted phenyl group, more preferably an alkyl group having 8 to 18 carbon atoms or an alkyl-substituted phenyl group substituted with an alkyl group having 8 to 18 carbon atoms.

[0036] Examples of acidic phosphate esters include those having a hydrocarbon group having 1 to 24 carbon atoms (such as an aryl group, an alkyl group, an alkyl group and an alkenyl group whose carbon chain may be partially substituted with an amide bond or an ester bond), such as mono- or di-alkyl acid phosphate, mono- or diaryl phosphate, mono- or dialkenyl phosphate, and alkylaryl phosphate. The alkyl group, aryl group and alkenyl group in the acidic phosphate ester are the same as those in the above-mentioned phosphate ester. Examples of acidic phosphate esters include mono- or di-2-ethylhexyl acid phosphate, mono- or di-decyl acid phosphate, mono- or di-dodecyl acid phosphate (mono- or di-lauryl acid phosphate), mono- or di-tridecyl acid phosphate, mono- or di-octadecyl acid phosphate (mono- or di-stearyl acid phosphate), mono- or di-9-octadecenyl acid phosphate (mono- or dioleyl acid phosphate), and the like. From the viewpoints of abrasion resistance and solubility, the acidic phosphate ester is preferably an acidic phosphate ester having a hydrocarbon group having 2 to 24 carbon atoms, more preferably an acidic phosphate ester having a hydrocarbon group having 8 to 18 carbon atoms. Furthermore, from the viewpoints of abrasion resistance and solubility, the hydrocarbon group is preferably an alkyl group or an alkyl-substituted phenyl group, more preferably an alkyl group having 8 to 18 carbon atoms or an alkyl-substituted phenyl group substituted with an alkyl group having 8 to 18 carbon atoms.

[0037] In the amine salt of an acidic phosphoric acid ester, the amine includes those other than the amine compound (B), and examples thereof include those in which at least one of the hydrogen atoms of ammonia is substituted with a hydrocarbon group having 1 to 24 carbon atoms, such as mono-substituted amines, di-substituted amines, and tri-substituted amines.

[0038] Examples of the hydrocarbon group having 1 to 24 carbon atoms in the amine compound (B) include an aliphatic hydrocarbon group having 1 to 24 carbon atoms and an aromatic ring-containing hydrocarbon group having 6 to 24 carbon atoms. Examples of the aromatic ring-containing hydrocarbon group having 6 to 24 carbon atoms include a phenyl group, an alkyl-substituted phenyl group substituted with an alkyl group having 1 to 4 carbon atoms, and a benzyl group.

[0039] In the amine salt of an acidic phosphoric acid ester, examples of the mono-substituted amine include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine, and benzylamine. Examples of di-substituted amines include dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, and dibenzylamine. Examples of tri-substituted amines include tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleyl monoethylamine, dilauryl propylamine, dioctyl monoethylamine, dihexyl propylamine, dibutyl monopropylamine, oleyl diethylamine, stearyl dipropylamine, lauryl diethylamine, octyl dipropylamine, butyl diethylamine, benzyl diethylamine, phenyl diethylamine, tolyl dipropylamine, and xylyl diethylamine.

[0040] In the amine salt of an acidic phosphoric acid ester, from the viewpoint of solubility, the amine is preferably an amine having a hydrocarbon group having 2 to 24 carbon atoms, more preferably an amine having a hydrocarbon group having 8 to 18 carbon atoms. Furthermore, from the viewpoints of abrasion resistance and solubility, the hydrocarbon group is preferably an alkyl group or an alkyl-substituted phenyl group, more preferably an alkyl group having 8 to 18 carbon atoms or an alkyl-substituted phenyl group substituted with an alkyl group having 8 to 18 carbon atoms.

[0041] As the amine salt of an acidic phosphate, from the viewpoints of abrasion resistance and solubility, an amine salt of an acidic phosphate having a hydrocarbon group having 2 to 24 carbon atoms and an amine having a hydrocarbon group having 2 to 24 carbon atoms is preferred, and an amine salt of an acidic phosphate having a hydrocarbon group having 8 to 18 carbon atoms and an amine having a hydrocarbon group having 8 to 18 carbon atoms is more preferred.

[0042] The phosphite ester includes those having a hydrocarbon group having 1 to 24 carbon atoms (such as an aryl group, an alkyl group, an alkyl group and an alkenyl group whose carbon chain may be partially substituted with an amide bond or an ester bond), and examples thereof include dialkyl hydrogen phosphite, diaryl hydrogen phosphite, dialkenyl hydrogen phosphite, and alkylaryl hydrogen phosphite. In the phosphite ester, the alkyl group, the aryl group and the alkenyl group are the same as in the phosphate ester. Examples of phosphite esters include di-2-ethylhexyl hydrogen phosphite, didecyl hydrogen phosphite, didodecyl hydrogen phosphite (dilauryl hydrogen phosphite), dioctadehydrogen phosphite (distearyl hydrogen phosphite), di-9-octadecenyl hydrogen phosphite (dioleyl hydrogen phosphite), and diphenyl hydrogen phosphite. From the viewpoints of abrasion resistance and solubility, the phosphite is preferably a phosphite having a hydrocarbon group having 2 to 24 carbon atoms, more preferably a phosphite having a hydrocarbon group having 8 to 18 carbon atoms. Furthermore, from the viewpoints of abrasion resistance and solubility, the hydrocarbon group is preferably an alkyl group or an alkyl-substituted phenyl group, more preferably an alkyl group having 8 to 18 carbon atoms or an alkyl-substituted phenyl group substituted with an alkyl group having 8 to 18 carbon atoms.

[0043] The thiophosphate ester includes those in which at least one of the four oxygen atoms of the phosphate ester is substituted with a sulfur atom, and examples thereof include tributyl thiophosphate, triisobutyl thiophosphate, triisopentyl thiophosphate, trihexyl thiophosphate, tribenzyl thiophosphate, tris(o-tolyl) thiophosphate, and triheptyl thiophosphate. From the viewpoints of abrasion resistance and solubility, the thiophosphate ester is preferably a thiophosphate ester having a hydrocarbon group having 2 to 24 carbon atoms, more preferably a thiophosphate ester having a hydrocarbon group having 8 to 18 carbon atoms. Furthermore, from the viewpoints of abrasion resistance and solubility, the hydrocarbon group is preferably an alkyl group or an alkyl-substituted phenyl group, more preferably an alkyl group having 8 to 18 carbon atoms or an alkyl-substituted phenyl group substituted with an alkyl group having 8 to 18 carbon atoms.

[0044] The acidic thiophosphate ester includes those in which at least one of the four oxygen atoms of the acidic phosphate ester is substituted with a sulfur atom, and examples thereof include mono- or di-2-ethylhexyl acid thiophosphate, mono- or di-decyl acid thiophosphate, mono- or di-dodecyl acid thiophosphate (mono- or di-lauryl acid thiophosphate), mono- or di-tridecyl acid thiophosphate, mono- or di-octadecyl acid thiophosphate (mono- or di-stearyl acid thiophosphate), mono- or di-9-octadecenyl acid thiophosphate (mono- or di-oleyl acid thiophosphate), and the like.

[0045] In the amine salt of an acidic thiophosphate, the amine is the same as the amine in the amine salt of an acidic phosphoric acid, and the preferred amines are also the same.

[0046] The thiophosphite ester includes those in which at least one of the three oxygen atoms of the above-mentioned phosphite ester is substituted with a sulfur atom, and examples thereof include di-2-ethylhexyl hydrogenthiophosphite, didecyl hydrogenthiophosphite, didodecyl hydrogenthiophosphite (dilauryl hydrogenthiophosphite), dioctadehydrogenthiophosphite (distearyl hydrogenthiophosphite), di-9-octadecenyl hydrogenthiophosphite (dioleyl hydrogenthiophosphite), diphenyl hydrogenthiophosphite, and the like.

[0047] From the viewpoint of wear resistance, the phosphorus compound is preferably at least one selected from the group consisting of phosphate esters, acidic phosphate esters, thiophosphate esters, amine salts of acidic phosphate esters, and phosphites, and more preferably the amine salts of acidic phosphate esters and thiophosphate esters.

[0048] The water-soluble lubricant of the present invention may contain an oiliness agent (E), a dialkyl polysulfide (F), an antioxidant (G) and a rust inhibitor (H) as necessary.

[0049] <Oil-based agent (E)> The oil agent (E) used in the present invention means an agent having a hydrocarbon group and a polar group, and capable of forming a molecular film on the metal surface by adsorbing the polar group to the metal surface. Examples of the oil agent (E) include a compound (E1) represented by the following general formula (3) and / or an amine salt (E2) of an aliphatic monocarboxylic acid having an aliphatic hydrocarbon group having 8 to 24 carbon atoms. The oil agent (E) may be used alone or in combination of two or more kinds. The amine in the amine salt (E2) does not include the amine compound (B). (R 3 COO) h R 4 [-(OA 11 ) s -OH] 4-h (3) [R 3is an aliphatic hydrocarbon group having 8 to 24 carbon atoms, which may have one or more double bonds, (OA 11 ) is an oxyalkylene group having 2 to 4 carbon atoms, R 4 is a residue obtained by removing a hydroxyl group from sorbitan, h is an integer of 1 to 3, s is an integer of 1 to 1000, and when s is 2 or more, s A 11 may be the same or different.]

[0050] R 3 is an aliphatic hydrocarbon group having 8 to 24 carbon atoms, which may have one or more double bonds, (OA 11 ) is an oxyalkylene group having 2 to 4 carbon atoms, R 4 represents a residue obtained by removing a hydroxyl group from sorbitan, h represents an integer of 1 to 3, s represents the number of moles of alkylene oxide added and is an integer of 1 to 1000, and when s is 2 or more, s A 11 may be the same or different. (OA 11 ) s The moiety may be added in a random or block manner. h is preferably 1 or 2, and more preferably 1. A 11 is an alkylene group having 2 to 4 carbon atoms. Examples of the alkylene group having 2 to 4 carbon atoms include an ethylene group, a 1,2- or 1,3-propylene group, and a 1,2-, 1,3-, or 1,4-butylene group. In the compound (E1) contained in the water-soluble lubricant, the average value of s is preferably 1 to 300, more preferably 6 to 106, particularly preferably 6 to 30, and most preferably 6 to 20, from the viewpoints of biodegradability and low-temperature fluidity.

[0051] Examples of the compound (E1) include alkylene oxide (e.g., EO, PO, BO, tetrahydrofuran) adducts of sorbitan mono- or di-fatty acid esters {esters of sorbitan and saturated fatty acids (including those having 8 to 24 carbon atoms, such as caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid) and / or unsaturated fatty acids (including those having 8 to 24 carbon atoms, such as oleic acid, linoleic acid, linolenic acid)}. Among these, from the viewpoint of biodegradability, preferred are EO adducts of sorbitan mono-fatty acid esters and EO / PO adducts of sorbitan mono-fatty acid esters. As the fatty acid, a fatty acid having 8 to 22 carbon atoms is preferred from the viewpoints of biodegradability and lubricity. The average number of moles of alkylene oxide added per molecule of compound (E1) is preferably from 10 to 300 moles, and more preferably from 20 to 60 moles, from the viewpoints of biodegradability and lubricity.

[0052] The number average molecular weight of the compound (E1) is preferably from 500 to 10,000, more preferably from 750 to 5,000, and even more preferably from 1,000 to 4,000, from the viewpoints of biodegradability and low-temperature fluidity. The compound (E1) may be used alone or in combination of two or more kinds.

[0053] In the amine salt (E2) of an aliphatic monocarboxylic acid having an aliphatic hydrocarbon group having 8 to 24 carbon atoms, examples of the aliphatic monocarboxylic acid include monocarboxylic acids having 8 to 24 carbon atoms (saturated or unsaturated fatty acids (e.g., octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentanoic acid, hexanoic acid, palmitoleic acid, heptadecanoic acid, octadecanoic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid, eicosanoic acid, docosanoic acid, etc.), etc. In the amine salt (E2), examples of the amine include alkylamines (having 1 to 24 carbon atoms) (e.g., methylamine, ethylamine, propylamine, etc.), dialkylamines (including those having 2 to 24 carbon atoms, such as dimethylamine, diethylamine, dipropylamine, etc.), and trialkylamines (including those having 3 to 24 carbon atoms, such as trimethylamine, triethylamine, tripropylamine, etc.). Of these, triethylamine is preferred from the viewpoint of load resistance. Examples of the amine salt (E2) include trimethylamine octanoate, triethylamine octanoate, trimethylamine nonanoate, triethylamine nonanoate, trimethylamine decanoate, and triethylamine decanoate. Among these, from the viewpoint of load-bearing property, trimethylamine salt of octanoic acid, triethylamine salt of octanoic acid, trimethylamine salt of nonanoic acid, triethylamine salt of nonanoic acid, trimethylamine salt of decanoic acid, and triethylamine salt of decanoic acid are preferred, and triethylamine salt of octanoic acid, triethylamine salt of nonanoic acid, and triethylamine salt of decanoic acid are more preferred.

[0054] <Dialkyl polysulfide (F)> The dialkyl polysulfide (F) that can be used in the present invention is a compound that functions as a load-bearing additive. Examples of the dialkyl polysulfide (F) include dialkyl polysulfides having an alkyl group having 2 to 24 carbon atoms. The dialkyl polysulfides (F) may be used alone or in combination of two or more. Examples of the dialkyl polysulfide (F) include dialkyl polysulfides having a linear alkyl group {e.g., diethyl polysulfide, dipropyl polysulfide, di-n-butyl polysulfide, di-n-hexyl polysulfide, di-n-octyl polysulfide, di-n-nonyl polysulfide, di-n-decyl polysulfide, di-n-undecyl polysulfide, di-n-dodecyl polysulfide, di-n-tridecyl polysulfide, di-n-tetradecyl polysulfide, di-n- pentadecyl polysulfide, di-n-hexadecyl polysulfide, di-n-heptadecyl polysulfide, di-n-octadecyl polysulfide, etc.}, dialkyl sulfides having a branched alkyl group {for example, bis(hexane-2-yl) polysulfide, bis(octane-2-yl) polysulfide, bis(decen-2-yl) polysulfide, bis(dodecen-2-yl) polysulfide, bis(2,4,4-trimethylpentan-2-yl) polysulfide, etc.}, and the like. Among these, dialkyl polysulfides having an alkyl group with 6 to 24 carbon atoms are preferred, dialkyl polysulfides having an alkyl group with 6 to 18 carbon atoms are more preferred, and dialkyl polysulfides having an alkyl group with 8 to 12 carbon atoms are particularly preferred.

[0055] From the viewpoint of wear resistance, the sulfur content in the dialkyl polysulfide (F) is preferably from 10 to 40% by weight, and more preferably from 19.2 to 33.3% by weight, based on the weight of (F).

[0056] The kinetic viscosity of dialkyl polysulfide at 40°C is 10 to 100 mm from the viewpoint of lubrication. 2 / s is preferable, and 10 to 50 mm 2 / s.

[0057] The dialkyl polysulfide (F) can be produced by a known method, for example, a method of sulfurizing an olefin, a method of crosslinking a mercaptan with sulfur, or the like. In addition, the dialkyl polysulfide (F) is commercially available, and for example, products available include those manufactured by DIC Corporation (dialkyl polysulfide (a mixture of polysulfides in which the alkyl group has 8 to 10 carbon atoms), product name "Dailube IS-30") and those manufactured by Arkema Corporation (di-tert-dodecyl polysulfide, product name "TPS20").

[0058] <Antioxidant (G)> Examples of the antioxidant (G) include phenol-based antioxidants such as 2,6-di-tert-butyl-p-cresol, 2,4-dimethyl-6-tert-butylphenol, and 4,4'-butylidenebis(6-tert-butylmetacresol); amine-based antioxidants such as N-phenyl-4-octylphenylamine and bis(4-octylphenyl)amine; zinc dihydrocarbyl dithiophosphate and zinc diallyl dithiophosphate having a carbyl group having 1 to 36 carbon atoms; and the like. Of these, phenol-based antioxidants are preferred from the viewpoint of solubility.

[0059] <Rust inhibitor (H)> Examples of the rust inhibitor (H) include benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, amides of the above-mentioned aliphatic monocarboxylic acids and amines, and alkali metal (sodium, potassium, etc.) salts of the above-mentioned aliphatic monocarboxylic acids. Of these, benzotriazole-based compounds are preferred from the viewpoint of solubility.

[0060] <Water-soluble lubricant> The water-soluble lubricant of the present invention contains the compound (A), the amine compound (B), and the hydroxy acid (C). The water-soluble lubricant of the present invention contains 85 to 99.7% by weight of the compound (A), 0.1 to 10% by weight of the amine compound (B), and 0.2 to 5% by weight of the hydroxy acid (C) based on the total weight of the water-soluble lubricant. In the present invention, the molar ratio of the hydroxyl group derived from the amine compound (B) to the hydroxyl group derived from the hydroxy acid (C) [hydroxyl group derived from the hydroxy acid (C) / hydroxyl group derived from the amine compound (B)] is 0.03 to 0.4.

[0061] The content of compound (A) in the water-soluble lubricant is 85 to 99.7% by weight, preferably 89.0 to 97.0% by weight, and more preferably 93.0 to 96.0% by weight, based on the total weight of the water-soluble lubricant. When the content of compound (A) is 85% by weight or more, good biodegradability is achieved, and when it is 99.7% by weight or less, good lubricity is achieved.

[0062] The content of the amine compound (B) in the water-soluble lubricant is 0.1 to 10% by weight, preferably 2.0 to 8.0% by weight, and more preferably 3.0 to 5.0% by weight, based on the total weight of the water-soluble lubricant. When the content of the amine compound (B) is 0.1% by weight or more, the rust prevention property is good, and when it is 10% by weight or less, the biodegradability and lubricity are good.

[0063] The content of the hydroxy acid (C) in the water-soluble lubricant is 0.2 to 5% by weight, preferably 1.0 to 3.0% by weight, and more preferably 1.0 to 2.0% by weight, based on the total weight of the water-soluble lubricant. When the content of the hydroxy acid (C) is 0.2% by weight or more, the metal elution suppression effect is good, and when it is 5% by weight or less, the lubricity is good.

[0064] The molar ratio of the hydroxyl group derived from the amine compound (B) to the hydroxyl group derived from the hydroxy acid (C) in the water-soluble lubricant of the present invention [hydroxyl group derived from the hydroxy acid (C) / hydroxyl group derived from the amine compound (B)] is 0.03 to 0.4, and from the viewpoint of rust prevention and metal elution suppression, it is preferably 0.1 to 0.35, more preferably 0.12 to 0.35. By being 0.03 or more and 0.4 or less, metal elution by the amine compound (B) and the hydroxy acid (C) can be suppressed without impairing the rust prevention due to the metal orientation of the amine compound (B). In this specification, the "molar ratio of the hydroxyl group derived from the amine compound (B) to the hydroxyl group derived from the hydroxy acid (C) [hydroxyl group derived from the hydroxy acid (C) / hydroxyl group derived from the amine compound (B)]" may be described as "molar ratio [OH derived from the hydroxy acid (C) / OH derived from the amine (B)]".

[0065] When the water-soluble lubricant further contains a phosphorus compound (D), the content of the phosphorus compound (D) is preferably 0.1 to 5.0 wt %, and more preferably 0.1 to 1.0 wt %, based on the total weight of the water-soluble lubricant, from the viewpoints of wear resistance and biodegradability. The weight ratio of the phosphorus compound (D) to the hydroxy acid (C) in the water-soluble lubricant [weight of phosphorus compound (C) / weight of hydroxy acid (D), denoted as (C / D)] is 0.04 to 50, and from the viewpoint of metal elution inhibition and lubricity, is preferably 1.0 to 30, and more preferably 1.0 to 6.7. When it is 0.04 or more, the metal elution inhibition effect tends to be further improved, and when it is 50 or less, the lubricity tends to be good. When the weight ratio (C / D) is within the above range, the metal elution inhibition effect by the hydroxy acid (C) and the adsorption coating formation effect by the phosphorus compound (D) are well balanced, a phosphate coating is easily formed on the metal surface, and the wear resistance tends to be excellent.

[0066] From the viewpoints of wear resistance and biodegradability, the content of the oily agent (E) in the water-soluble lubricant is preferably 5.0% by weight or less, and more preferably 3.0% by weight or less, based on the total weight of the water-soluble lubricant. From the viewpoints of wear resistance and biodegradability, the content of the dialkyl polysulfide (F) in the water-soluble lubricant is preferably 5.0% by weight or less, and more preferably 2.0% by weight or less, based on the total weight of the water-soluble lubricant. When the water-soluble lubricant contains an antioxidant (G), the content of the antioxidant (G) in the water-soluble lubricant is preferably 0.1 to 5 wt %, and more preferably 0.1 to 2.0 wt %, based on the total weight of the water-soluble lubricant, from the viewpoints of antioxidant properties and biodegradability. From the viewpoints of rust prevention and biodegradability, the content of the rust inhibitor (H) in the water-soluble lubricant is preferably 5.0% by weight or less, and more preferably 2.0% by weight or less, based on the total weight of the water-soluble lubricant.

[0067] The water-soluble lubricant of the present invention may contain components other than those described above. For example, antifoaming agents, pour point depressants, viscosity index improvers, mold inhibitors, friction modifiers, surfactants, etc. may be used appropriately depending on the intended use and performance. The antifoaming agent includes silicone oil, metal soap, fatty acid ester, and the like. Pour point depressants include condensates of chlorinated paraffins with naphthalene or phenol, polyalkyl acrylates or methacrylates, polybutenes, polyalkylstyrenes, polyvinyl acetates, and the like. Viscosity index improvers include polymethacrylates, polyisobutylenes, olefin copolymers, polyalkylstyrenes, and the like. Examples of the mildew inhibitor include phenolic compounds, formaldehyde donor compounds, salicylanilide compounds, and the like. The total content of these components is preferably 3.0% by weight or less, more preferably 2.0% by weight or less, and particularly preferably 1.0% by weight or less, based on the total amount of the water-soluble lubricant.

[0068] The water-soluble lubricant of the present invention can be produced by mixing the compound (A), the amine compound (B), the hydroxy acid (C), and other components used as necessary by a general method.

[0069] The biodegradability of the water-soluble lubricant (based on OECD test method 301F) is preferably 60% or more, and more preferably 70% or more. The kinetic viscosity of water-soluble lubricants at 40°C (based on JIS K 2283) is 10 to 150 mm 2 / s is preferred.

[0070] The pH (25° C.) of a 50% by weight aqueous solution of the water-soluble lubricant is preferably 7.0 to 12.0, and more preferably 8.0 to 10.0, from the viewpoint of suppressing metal elution. In the present invention, the pH can be measured using a commercially available pH meter (for example, manufactured by Horiba, Ltd.).

[0071] The water-soluble lubricant of the present invention has excellent biodegradability and rust prevention properties, and has an excellent metal elution suppression effect, and can therefore be suitably used as bearing oils, hydraulic oils, gear oils, etc. for automobiles, construction machinery, ships, metal processing machinery, etc. Furthermore, the water-soluble lubricant of the present invention has the characteristics of being biodegradable, water-soluble, and low toxicity even if it leaks into seawater, and is therefore particularly suitable as a bearing oil, hydraulic oil, or gear oil (e.g., thruster oil) for ships. EXAMPLES

[0072] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these.

[0073] <Production of Production Example 1 (B2-1)> 99 parts by weight of cyclohexylamine (reagent manufactured by Kanto Chemical Co., Ltd., purity 100%) (1 mole) was charged into an autoclave equipped with a temperature control device, and 88 parts by weight (2 moles) of EO charged in a pressure-resistant funnel was dropped while controlling the reaction temperature to be kept at 140 to 150°C, and then the reaction was continued for another 2 hours at 145°C. After that, the mixture was cooled to 80°C, and the pressure was reduced to 600 Pa or less to perform dehydration, and 187 parts by weight of a cyclohexylamine EO 2 mole adduct was obtained.

[0074] <Production of Production Example 2 (B2-2)> The same procedure as in Production Example 1 was repeated except that 88 parts by weight (2 moles) of EO was replaced with 116 parts by weight (2 moles) of PO, to obtain 215 parts by weight of a cyclohexylamine / PO 2-mol adduct.

[0075] <Examples 1 to 20 and Comparative Examples 1 to 4> The raw materials listed in Table 2 were mixed by stirring at 50 to 60°C to obtain 100 parts each of the water-soluble lubricants (V-1) to (V-20) of the present invention and the comparative water-soluble lubricants (V'-1) to (V'-4). These kinetic viscosities at 40°C (mm 2 / s) was measured under the following conditions in accordance with JIS K 2283.

[0076] <Method of measuring kinetic viscosity> Equipment: Automatic viscosity measuring device (VMC-252 type); manufactured by Rigosha Co., Ltd. Viscometer: Ubbelohde viscometer (viscosity meter number 2) Measurement temperature: 40℃

[0077] [Table 2]

[0078] The abbreviations in Table 2 represent the following compositions. (A-1) EO adduct of methanol; (Mn=500, biodegradability=88%) (A-2) EO / PO adduct of propanol; (Mn=1,000, molar ratio EO / PO=79 / 21, biodegradability=84%) (A-3) EO / PO adduct of butanol; (Mn=1,000, molar ratio EO / PO=56 / 44, biodegradability=79%) (A-4) EO / PO adduct of butanol; (Mn=1,800, molar ratio EO / PO=56 / 44, biodegradability=78%) (A-5) EO adduct of butanol; (Mn=850, biodegradability=85%) (A-6) EO / PO adduct of hexanol; (Mn=900, molar ratio EO / PO=60 / 40, biodegradability=79%) (A-7) EO / PO adduct of octanol; (Mn=1,200, molar ratio EO / PO=56 / 44, biodegradability=78%) (A-8) PEG-200: polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., Mn = 200, biodegradability = 90%) (A-9) PEG-400; polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd.), Mn=400, biodegradability=85%) (A-10) PEG-1000: polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., Mn = 1000, biodegradability = 80%) (A-11) EO / PO adduct of diethylene glycol; (Mn=2,000, molar ratio EO / PO=63 / 37, biodegradability=85%) (A-12) EO / PO adduct of diethylene glycol; (Mn=1,700, molar ratio EO / PO=66 / 34, biodegradability=87%) (A-13) EO / PO adduct of diethylene glycol; (Mn=1,500, molar ratio EO / PO=69 / 31, biodegradability=88%) (A-14) EO adduct of glycerin; (Mn=600, biodegradability=64%) (A-15) EO / PO adduct of trimethylolpropane; (Mn=1,000, molar ratio EO / PO=56 / 44, biodegradability=75%) (A-16) EO / PO adduct of pentaerythritol; (Mn=1,500, molar ratio EO / PO=79 / 21, biodegradability=75%) (A-17) EO adduct of sorbitol; (Mn=1,200, biodegradability=75%) (B2-1) Cyclohexylamine EO 2 mole adduct: obtained in Production Example 1 (B2-2) Cyclohexylamine PO 2-mol adduct: Obtained in Production Example 2

[0079] <Evaluation example> The resulting water-soluble lubricant was tested for biodegradability, rust prevention, and metal elution. The test methods are as follows, and the results are shown in Table 2.

[0080] (1) Biodegradable The biodegradability was measured by measuring the biochemical oxygen consumption (BOD) before and after 28 days of incubation in accordance with OECD test method 301F. The activated sludge used was purchased from the Chemicals Evaluation and Research Institute, Japan. The measurement results were evaluated according to the following criteria. ☆: Biodegradability 80% or more ◎: Biodegradability: 70% to less than 80% ○: Biodegradability: 60% to less than 70% ×: Biodegradability less than 60%

[0081] (2) Rust prevention test The test conforms to the test method for rust prevention performance of lubricating oils (JIS K 2510). A polished and cleaned steel bar (S20C) was immersed in a mixed solution containing 10% by weight of artificial seawater based on the weight of the water-soluble lubricant at 60°C for three days, and then observed for rust formation. The mixed solution was stirred continuously during immersion. The measurement results were evaluated according to the following criteria. ☆: No rust is observed ○: Minor (6 or less rust spots with a diameter of 1 mm or less on the surface of the test piece) △: Moderate (6 or less rust spots with a diameter of 1 mm or less on the surface of the test piece and / or rust is found on 5% or less of the surface area of ​​the test piece) ×: Severe (rust is observed on more than 5% of the surface area of ​​the test piece)

[0082] (3) Metal elution test (white metal: Japan Industrial Standards: WJ-2) <Evaluation method> A test piece (10 mm x 7 mm x 3 mm) made of white metal (Japan Industrial Standards: WJ-2) was washed with 50 ml of each solvent (toluene, acetone), and then completely immersed in 20 g of water-soluble lubricant in a 100 mL plastic container. The metal (Sn) content in the water-soluble lubricant after aging at 80°C for 7 days was analyzed by ICP. <About metal elution amount> The dimensions of each test piece were measured, and the amount of metal eluted per unit surface area (μg / mm 2 ) was calculated. The measurement results were evaluated according to the following criteria. ☆:1.0μg / mm 2 below ○: 1.0 μg / mm 2 Super 2.0μg / mm 2 below △: 2.0μg / mm 2 Super 3.0μg / mm 2 below ×: 3.1μg / mm 2 super

[0083] (3) Metal elution test (white metal: Japan Industrial Standards: WJ-7) <Evaluation method> A test piece (10 mm x 7 mm x 3 mm) made of white metal (Japan Industrial Standards: WJ-7) was washed with 50 ml of each solvent (toluene, acetone), and then completely immersed in 20 g of water-soluble lubricant in a 100 mL plastic container. The metal (Pb) content in the water-soluble lubricant after aging at 80°C for 7 days was analyzed by ICP. <About metal elution amount> The dimensions of each test piece were measured, and the amount of metal eluted per unit surface area (μg / mm 2 ) was calculated. The measurement results were evaluated according to the following criteria. ☆: 3.0μg / mm 2 below ○: 3.0 μg / mm 2 Super 5.0μg / mm 2 below △: 5.0μg / mm 2 Super 10.0μg / mm 2 below ×:10.0μg / mm 2 super

[0084] <Examples 21 to 40> The water-soluble lubricant obtained in Example 1, 6, 7, 15 or 16 was mixed with each of the components shown in Table 3 by stirring at 50 to 60°C to obtain 100 parts each of the water-soluble lubricants (W-1) to (W-20) of the present invention. These kinetic viscosities at 40°C (mm 2 / s) was measured under the above conditions in accordance with JIS K 2283.

[0085] [Table 3]

[0086] The abbreviations in Table 3 represent the following compositions. (D-1) Acidic phosphate amine salt-1: A salt of a mixture of acidic phosphate esters having an alkyl group with 8 to 12 carbon atoms and a mixture of amines having an alkyl group with 6 to 12 carbon atoms. (D-2) Acidic phosphate amine salt-2: A salt of an acidic phosphate mixture having an alkyl group with 8 to 10 carbon atoms and an amine mixture having an alkyl group with 6 to 12 carbon atoms. (D-3) Acidic phosphate amine salt-3: A salt of an acidic phosphate mixture having an alkyl group with 8 carbon atoms and an amine mixture having an alkyl group with 8 carbon atoms. (D-4) Thiophosphate-1: A thiophosphate having an alkylphenyl group having an alkyl group having 9 carbon atoms, and one of the four oxygen atoms of the phosphate ester being replaced with a sulfur atom. (D-5) Dithiophosphate-2: A mixture of dithiophosphates having an alkyl group with 8 to 12 carbon atoms and in which two of the four oxygen atoms of the phosphate are replaced with sulfur atoms. (D-6) Thiophosphate-3: A dithiophosphate mixture having two alkyl groups having 4 to 8 carbon atoms and one {-CH2CH2COOCH3 group}, in which two of the four oxygen atoms of the phosphate ester are replaced with sulfur atoms. (D-7) Mixtures of acidic phosphoric acid ester amine salts and acidic thiophosphate ester amine salts: mixtures of salts of acidic phosphoric acid ester mixtures having an alkyl group with 8 to 10 carbon atoms and amine mixtures having an alkyl group with 6 to 12 carbon atoms, and mixtures of salts of acidic thiophosphate mixtures having an alkyl group with 8 to 12 carbon atoms and amine mixtures having an alkyl group with 6 to 12 carbon atoms. (E-1) EO adduct of sorbitan mono fatty acid ester: IONET T-20C, manufactured by Sanyo Chemical Industries, Ltd. (F-1) Polysulfide compound with alkyl group having 8 to 10 carbon atoms: manufactured by DIC Corporation (dialkyl polysulfide (mixture of alkyl groups having 8 to 10 carbon atoms), product name "Dailube IS-30")

[0087] <Evaluation example> The resulting water-soluble lubricant was tested for its biodegradability and lubricity. The test methods are as follows, and the results are shown in Table 3.

[0088] (4) Lubricity (wear performance test: high-speed four-ball test) Abrasion evaluation was carried out according to ASTM D-4172. The average diameter of the wear scar on the lower test ball was observed. The smaller the diameter of the wear scar, the less likely the wear is to occur, and the better the performance. The measurement results were evaluated according to the following criteria. Shaft speed: 1450 rpm Test steel ball: 1 / 2 inch for ball bearings (JIS high grade) Test temperature: 70℃ Test load: 300N Abrasion test time: 30 minutes ☆: Wear scar diameter is less than 0.30mm ○: Wear scar diameter is 0.30 mm or more and less than 0.40 mm △: Wear scar diameter is 0.40mm or more and less than 0.50mm ×: Wear scar diameter is 0.50 or more

[0089] From the results in Table 2, it can be seen that the water-soluble lubricants of the present invention of Examples 1 to 20 have high biodegradability of 70% or more, excellent rust prevention evaluation, small amount of metal elution, and excellent biodegradability, rust prevention, and metal elution suppression effects. On the other hand, it can be seen that Comparative Example 1, in which the molar ratio of the hydroxyl group derived from the amine compound (B) to the hydroxyl group derived from the hydroxyl acid (C) [OH derived from hydroxy acid (C) / OH derived from amine (B)] is 0.45 (i.e., exceeds 0.4), Comparative Example 2, which does not contain the amine compound (B) and hydroxy acid, and Comparative Examples 3 and 4, which do not contain the amine compound (B) or hydroxy acid, are inferior in rust prevention and metal elution effects. Furthermore, a comparison of Examples 21 to 37 with Examples 38 to 39 in Table 3 shows that, from the viewpoint of enhancing the lubricity of the water-soluble lubricant of the present invention, it is preferable to contain a phosphorus compound (D). [Industrial Applicability]

[0090] The water-soluble lubricant of the present invention is a water-soluble lubricant that is excellent in biodegradability and rust prevention performance, and is excellent in metal elution suppression, so it can be used for gear oil (differential oil and industrial gear oil, etc.), MTF, transmission oil [ATF, DCTF and belt-CVTF, etc.], traction oil (toroidal-CVTF, etc.), shock absorber oil, power steering oil, hydraulic oil (construction machine hydraulic oil and industrial hydraulic oil, etc.) and engine oil, and is particularly suitable for hydraulic oil and gear oil.In addition, the water-soluble lubricant of the present invention is highly biodegradable even if it leaks into seawater, and is also excellent in rust prevention and metal elution suppression effect, so it can be preferably used as a water-soluble lubricant for ships, especially as a water-soluble lubricant for ship thrusters.

Claims

1. A water-soluble lubricant comprising a compound (A) represented by the following general formula (1), an amine compound (B) represented by the following general formula (2), and a hydroxy acid (C), The number average molecular weight of the compound (A) contained in the water-soluble lubricant is less than 2000; the weight ratio of the compound (A) is 85 to 99.7% by weight, the weight ratio of the amine compound (B) is 0.1 to 10% by weight, and the weight ratio of the hydroxy acid (C) is 0.2 to 5% by weight, based on the total weight of the water-soluble lubricant; The water-soluble lubricant has a molar ratio of the hydroxyl group derived from the amine compound (B) to the hydroxyl group derived from the hydroxy acid (C) [hydroxy group derived from the hydroxy acid (C) / hydroxy group derived from the amine compound (B)] of 0.03 to 0.

4. R １ -[-O-(A １ O) ｊ -R ２ ] ｋ (1) [In formula (1), R １ is a hydrogen atom or a k-valent hydrocarbon group having 1 to 12 carbon atoms, k is an integer from 1 to 6, A １ Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, j is an integer of 1 or more representing the number of moles of the alkyleneoxy group added, and R ２ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms.] N(Q) （３－ｍ） -[(A ２ O) ｎ H] ｍ (2) [In formula (2), A ２ Each O independently represents an alkyleneoxy group having 2 to 4 carbon atoms, n is an integer from 1 to 20, and when n is 2 or more, A ２ O may be the same or different, m is an integer of 1 to 3, and when m is 2 or more, there are a plurality of [(A ２ O) ｎ H] may be the same or different, and each Q independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 24 carbon atoms.

2. The water-soluble lubricant according to claim 1, comprising, as the amine compound (B), an amine in which m is 2 and Q is an aliphatic hydrocarbon group having 1 to 24 carbon atoms in general formula (2), and a compound in which m is 1 to 2 and Q is a hydrogen atom in general formula (2), or an amine in which m is 3.

3. 2. The water-soluble lubricant according to claim 1, wherein the compound (A) is a compound represented by general formula (1), in which k is an integer of 1 to 3.

4. The compound (A) is represented by the general formula (1), １ 2. The water-soluble lubricant according to claim 1, which is a compound having only an ethyleneoxy group as O and / or a compound having an ethyleneoxy group and a propyleneoxy group as O.

5. The water-soluble lubricant according to claim 4, wherein the ratio (EO / PO) of the number of moles of propyleneoxy groups (PO) constituting the compound (A) contained in the water-soluble lubricant to the number of moles of ethyleneoxy groups (EO) is 100 / 0 to 50 / 50.

6. 2. The water-soluble lubricant according to claim 1, wherein the hydroxy acid (C) is at least one selected from the group consisting of lactic acid, malic acid, citric acid and tartaric acid.

7. The water-soluble lubricant according to claim 1 , further comprising a phosphorus compound (D).

8. 8. The water-soluble lubricant according to claim 7, wherein the phosphorus compound (D) is at least one selected from the group consisting of phosphates, acid phosphates, thiophosphates, amine salts of acid phosphates, and phosphites.

9. 2. The water-soluble lubricant according to claim 1, wherein the compound (A) has a biodegradability of 60% or more.

10. The water-soluble lubricant has a kinetic viscosity of 10 to 150 mm at 40°C. ２ 2. The water-soluble lubricant according to claim 1, wherein

11. The water-soluble lubricant according to any one of claims 1 to 10, which is a bearing oil, hydraulic oil, or gear oil for ships.

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