Lubricating oil composition for sliding surfaces

Abstract

To provide a lubricating oil composition for sliding surfaces that can suppress the proliferation of microorganisms when the lubricating oil composition is mixed into water-soluble cutting oil.SOLUTION: A lubricating oil composition for sliding surfaces comprises a base oil (A) and a tertiary amine (B), in which the tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the cycloalkyl skeletons each independently has 5 or 6 ring members, and the alkyl group has 1 to 3 carbon atoms.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a lubricating oil composition for sliding surfaces. [Background technology]

[0002] Machine tools have sliding surfaces for moving tools, workpieces, etc. in desired directions, and lubricant oil compositions for sliding surfaces are used to smoothen the sliding motion. However, the sliding surface lubricant composition is mixed into a cutting oil tank installed in a machine tool and accelerates the deterioration of the water-soluble cutting oil. In detail, the sliding surface lubricant composition mixed into the cutting oil tank serves as a nutrient source for bacteria, promoting the proliferation of microorganisms in the cutting oil tank and accelerating the deterioration of the water-soluble cutting oil.

[0003] In the past, the proliferation of microorganisms in a cutting oil tank was suppressed by quickly separating the water-soluble cutting oil from a lubricating oil composition for sliding surfaces, thereby extending the service life of the water-soluble cutting oil (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-82789 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to quickly separate the water-soluble cutting oil from the sliding surface lubricating oil composition, an oil separation device such as an oil skimmer is required, but in recent years, there are an increasing number of cases where cutting oil tanks are not equipped with oil separation devices such as oil skimmers. Therefore, it is desired to create a sliding surface lubricating oil composition that can suppress the proliferation of microorganisms when the sliding surface lubricating oil composition is mixed with the water-soluble cutting oil in the cutting oil tank, etc.

[0006] An object of the present invention is to provide a lubricating oil composition for sliding surfaces which is capable of inhibiting the proliferation of microorganisms when the lubricating oil composition for sliding surfaces is contaminated with a water-soluble cutting oil. [Means for solving the problem]

[0007] According to the present invention, the following [1] to [4] are provided. [1] A lubricating oil composition for sliding surfaces, comprising a base oil (A) and a tertiary amine (B), The tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members in each of the cycloalkyl skeletons is independently 5 or 6; The alkyl group has 1 to 3 carbon atoms. [2] A method for using the sliding surface lubricant oil composition according to the above item [1] for inhibiting the proliferation of microorganisms in a water-soluble cutting oil. [3] A method for inhibiting the proliferation of microorganisms in water-soluble cutting oil, comprising the steps of mixing the sliding surface lubricating oil composition according to [1] above into a water-soluble cutting oil, and then retaining the sliding surface lubricating oil composition in the water-soluble cutting oil without removing it. [4] A method for producing a lubricant oil composition for sliding surfaces, comprising the step of mixing a base oil (A) and a tertiary amine (B), The tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members in each of the cycloalkyl skeletons is independently 5 or 6; A method for producing a lubricant oil composition for sliding surfaces, wherein the alkyl group has 1 to 3 carbon atoms. Effect of the Invention

[0008] According to the present invention, it is possible to provide a lubricating oil composition for sliding surfaces that can inhibit the proliferation of microorganisms when the lubricating oil composition for sliding surfaces is mixed into a water-soluble cutting oil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The upper and lower limit values ​​of the numerical ranges described in this specification can be combined in any way. For example, when "A to B" and "C to D" are described as numerical ranges, the numerical ranges "A to D" and "C to B" are also included in the scope of the present invention. In addition, unless otherwise specified, a numerical range of "lower limit value to upper limit value" described in this specification means not less than the lower limit value and not more than the upper limit value. In this specification, the numerical values ​​in the examples are numerical values ​​that can be used as upper or lower limits.

[0010] [Embodiments of the lubricating oil composition for sliding surfaces] The lubricating oil composition for sliding surfaces of the present embodiment contains a base oil (A) and a tertiary amine (B). The tertiary amine (B) has two cycloalkyl skeletons bonded to the nitrogen atom and one alkyl group bonded to the nitrogen atom. The cycloalkyl backbones each independently have 5 or 6 ring members. The alkyl group has 1 to 3 carbon atoms.

[0011] The present inventors have conducted extensive research to solve the above problems, and as a result have found that a lubricating oil composition for sliding surfaces containing a specific tertiary amine can solve the above problems. The mechanism by which the sliding surface lubricating oil composition of the present invention can solve the above problems is not clear, but it is presumed to be, for example, as follows. That is, it is presumed that the structure of the tertiary amine (B) effectively acts to reduce the activity of microorganisms and contributes to the inhibition of the proliferation of microorganisms in cutting oil tanks, etc. In addition, since the tertiary amine (B) is not easily volatilized, it can remain in the sliding surface lubricating oil composition for a long period of time. And, it is presumed that the tertiary amine (B) can remain in the sliding surface lubricating oil composition for a long period of time even after the sliding surface lubricating oil composition is mixed into the water-soluble cutting oil, and can fully exert its function.

[0012] In addition, since the tertiary amine (B) is highly oil-soluble, it is likely to remain in the lubricating oil composition for sliding surfaces even after the lubricating oil composition for sliding surfaces is mixed into the water-soluble cutting oil. Therefore, when microorganisms contact the lubricating oil composition for sliding surfaces mixed into the water-soluble cutting oil in search of a nutrient source, the microorganisms are also likely to come into contact with the tertiary amine (B) present in the lubricating oil composition for sliding surfaces. As a result, it is presumed that the probability of the microorganisms coming into contact with the tertiary amine (B) is increased, and the tertiary amine (B) reduces the activity of the microorganisms, thereby effectively suppressing their proliferation.

[0013] In the following description, the "sliding surface lubricant composition" will also be referred to simply as the "lubricant composition".

[0014] The lubricating oil composition of the present embodiment may be composed only of the base oil (A) and the tertiary amine (B), but may also contain any other components in addition to the base oil (A) and the tertiary amine (B) as long as the effects of the present invention are not significantly impaired. In the lubricating oil composition of this embodiment, the total content of the base oil (A) and the tertiary amine (B) is preferably 80 mass% or more, more preferably 85 mass% or more, even more preferably 90 mass% or more, and even more preferably 95 mass% or more, based on the total amount of the lubricating oil composition. Also, it is preferably 100 mass% or less, more preferably less than 100 mass%, even more preferably 99.5 mass% or less, and even more preferably 99.0 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the content is preferably 80% by mass to 100% by mass, more preferably 85% by mass to less than 100% by mass, even more preferably 90% by mass to 99.5% by mass, and even more preferably 95% by mass to 99.0% by mass.

[0015] Each component contained in the lubricating oil composition of this embodiment will be described in detail below.

[0016] <Base oil (A)> The lubricating oil composition of the present embodiment contains a base oil (A). As the base oil (A), for example, one or more types selected from mineral oils and synthetic oils that have conventionally been used as base oils for lubricating oil compositions for sliding surfaces can be used without any particular limitation.

[0017] Examples of mineral oils include atmospheric residual oils obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate base crude oil, or naphthenic crude oil; distillate oils obtained by vacuum distillation of these atmospheric residual oils; and mineral oils obtained by subjecting the distillate oils to one or more refining processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0018] Examples of synthetic oils include polyolefins such as polybutene, 1-octene oligomer, 1-decene oligomer, and hydrogenated products thereof, and ethylene-α-olefin copolymers; isoparaffin; various esters such as polyol esters and dibasic acid esters; various ethers such as polyphenyl ether; polyalkylene glycols; alkylbenzenes; alkylnaphthalenes; and GTL base oils obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process or the like (gas-to-liquid (GTL) wax).

[0019] The mineral oils may be used alone or in combination of two or more. The synthetic oils may be used alone or in combination of two or more. Also, one or more mineral oils may be used in combination with one or more synthetic oils.

[0020] In the lubricating oil composition of this embodiment, the base oil (A) preferably contains a mineral oil, the content of which is preferably 80 mass% to 100 mass%, more preferably 90 mass% to 100 mass%, even more preferably 95 mass% to 100 mass%, still more preferably 99 mass% to 100 mass%, and even more preferably 99.4 mass% to 100 mass%, based on the total amount of the base oil (A).

[0021] In addition, when the base oil (A) contains a mineral oil, the mineral oil may be one or more types selected from mineral oils classified into Groups I, II, and III in the category of the American Petroleum Institute (API), may be one or more types selected from mineral oils classified into Groups I and II, or may be a mineral oil classified into Group II. In the above case, two or more kinds of mineral oils classified into the same group may be mixed and used. For example, two or more types of mineral oils classified into the same group but having different viscosities may be mixed and used.

[0022] In addition, from the viewpoint of easily imparting oil film retention (stickiness) to the sliding parts, the base oil (A) preferably contains a polyolefin. The content of the polyolefin is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and even more preferably 0.3 mass% or more, based on the total amount of the base oil (A). Also, it is preferably 2.0 mass% or less, more preferably 1.5 mass% or less, and even more preferably 1.0 mass% or less. In addition, polyolefin has a kinetic viscosity of 2,000mm at 100°C to make it easier to maintain an oil film (stickiness) on the sliding parts. 2 / s~4,000mm 2 / s is preferable, and 2,000 mm 2 / s~3,500mm 2 / s is more preferable. Among the polyolefins, polybutene is preferred from the viewpoint of making it easier to impart oil film retention (stickiness) to the sliding parts.

[0023] The base oil (A) preferably has a kinetic viscosity at 40° C. (hereinafter also referred to as “40° C. kinetic viscosity”) of 10 mm 2 / s~220mm 2 / s. The kinetic viscosity of base oil (A) at 40°C is 220mm 2 / s or less, the sliding properties at medium and high sliding speeds of the lubricating oil composition are likely to be improved. In addition, the kinetic viscosity of the base oil (A) at 40°C is 10 mm 2 / s or more, the friction coefficient of the lubricating oil composition at low sliding speeds is more likely to be reduced. From the above viewpoint, the 40°C kinematic viscosity of the base oil (A) is more preferably 15mm 2 / s or more, more preferably 20 mm 2 / s or more, and even more preferably 25 mm 2 / s or more, and more preferably 150 mm 2 / s or less, more preferably 90 mm 2 / s or less, and even more preferably 75 mm 2 / s or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, it is more preferable that the range is 15 mm. 2 / s~150mm 2 / s, more preferably 20 mm 2 / s~90mm 2 / s, and even more preferably 25 mm 2 / s~75mm 2 / s. In this specification, the 40° C. kinematic viscosity of the base oil (A) means a value measured in accordance with JIS K2283:2000. When the base oil (A) is a mixed base oil containing two or more types of base oils, the mixed base oil preferably has a kinematic viscosity at 40° C. within the above range.

[0024] In this embodiment, the content of the base oil (A) in the lubricating oil composition is preferably 70.0 mass% or more, more preferably 80.0 mass% or more, and even more preferably 90.0 mass% or more, based on the total amount of the lubricating oil composition, and is preferably 99.0 mass% or less, more preferably 98.5 mass% or less, and even more preferably 98.0 mass% or less. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the content is preferably 70.0 mass % to 99.0 mass %, more preferably 80.0 mass % to 98.5 mass %, and even more preferably 90.0 mass % to 98.0 mass %.

[0025] <Tertiary amine (B)> The lubricating oil composition of this embodiment contains a tertiary amine (B). The tertiary amine (B) has two cycloalkyl skeletons bonded to the nitrogen atom and one alkyl group bonded to the nitrogen atom. The cycloalkyl backbones each independently have 5 or 6 ring members. The alkyl group has 1 to 3 carbon atoms. When the tertiary amine (B) does not have a cycloalkyl skeleton, when it has only one cycloalkyl skeleton bonded to the nitrogen atom, or when it has three cycloalkyl skeletons bonded to the nitrogen atom, the microbial growth inhibitory effect is less likely to be exerted. Furthermore, if the number of ring members in the cycloalkyl skeleton is 4 or less or 7 or more, the structural stability of the tertiary amine (B) is poor, and it is difficult to obtain the tertiary amine (B). Furthermore, when the number of carbon atoms in the alkyl group bonded to the nitrogen atom is 4 or more, the effect of inhibiting the proliferation of microorganisms is less likely to be exhibited.

[0026] Here, from the viewpoint of improving the microbial growth inhibiting effect, the tertiary amine (B) preferably contains one or more types selected from the compounds represented by the following general formula (1). [ka] [In the general formula (1), each symbol represents the following.] R 1 , R 2 , R 3 each independently represents an alkyl group having 1 to 3 carbon atoms. n1 and n2 each independently represent 0 or 1. When n1 is 0, m1 is an integer of 0 to 9. When n1 is 1, m1 is an integer from 0 to 11. When n2 is 0, m2 is an integer of 0 to 9. When n2 is 1, m2 is an integer from 0 to 11.

[0027] In the above general formula (1), R 1 , R 2 , R3 Alkyl groups which may be selected include methyl, ethyl, n-propyl, and isopropyl groups. Here, R 1 , R 2 , R 3 The number of carbon atoms in the alkyl group that can be selected as the alkyl group is preferably 1 to 2, and more preferably 1, from the viewpoint of improving the microbial proliferation inhibitory effect.

[0028] In the above general formula (1), n1 and n2 each independently represent 0 or 1. That is, when n1 and n2 are 0, the cycloalkyl groups in the above general formula (1) each represent a cyclopentyl group. When n1 and n2 are each 1, the cycloalkyl groups in the above general formula (1) each represent a cyclohexyl group. Here, from the viewpoint of improving the microbial proliferation inhibitory effect, it is preferable that both n1 and n2 are 1. That is, it is preferable that both cycloalkyl groups in the above general formula (1) are cyclohexyl groups.

[0029] In the above general formula (1), m1 and m2 each independently represent, from the viewpoint of improving the microbial proliferation inhibitory effect, preferably 0 to 6, more preferably 0 to 3, even more preferably 0 to 2, still more preferably 0 to 1, and even more preferably 0 (i.e., in the cycloalkyl group in the above general formula (1), the hydrogen atom of the cycloalkyl group is R 2 and R 3 is an unsubstituted cycloalkyl group that is not substituted with

[0030] Specific examples of preferred compounds as the tertiary amine (B) include N-methyldicyclohexylamine, N-methyldicyclopentylamine, N-ethyldicyclohexylamine, N-ethyldicyclopentylamine, N-propyldicyclohexylamine, N-propyldicyclopentylamine, N-propyldicyclohexylamine, N-propyldicyclopentylamine, etc. Among these, N-methyldicyclohexylamine and N-methyldicyclopentylamine are preferred, and N-methyldicyclohexylamine is more preferred.

[0031] <Tertiary amine (B) content> In the lubricating oil composition of this embodiment, the content of the tertiary amine (B) is not particularly limited, but from the viewpoint of easily exerting the microbial growth inhibition effect, it is preferably more than 1.00 mass%, more preferably 1.10 mass% or more, even more preferably 1.20 mass% or more, and even more preferably 1.25 mass% or more based on the total amount of the lubricating oil composition. Also, from the same viewpoint, it is preferably less than 3.00 mass%, more preferably less than 2.50 mass%, even more preferably less than 2.00 mass%, and even more preferably 1.75 mass% or less based on the total amount of the lubricating oil composition. The upper and lower limits of these numerical ranges can be arbitrarily combined. Specifically, the range is preferably more than 1.00% by mass and less than 3.00% by mass, more preferably 1.10% by mass or more and less than 2.50% by mass, even more preferably 1.20% by mass or more and less than 2.00% by mass, and still more preferably 1.25% by mass or more and 1.75% by mass or less.

[0032] <Content of nitrogen atoms derived from tertiary amine (B)> In the lubricating oil composition of this embodiment, the content of nitrogen atoms derived from the tertiary amine (B) is preferably 0.072 mass% to 0.21 mass%, more preferably 0.079 mass% to 0.18 mass%, even more preferably 0.086 mass% to 0.14 mass%, and still more preferably 0.090 mass% to 0.13 mass%, based on the total amount of the lubricating oil composition.

[0033] <Properties of tertiary amine (B)> (volatilization amount) The tertiary amine (B) preferably has a volatilization amount (60° C.×1 hour) of 10% or less, more preferably 7% or less, and even more preferably 5% or less, as measured by the method described in the Examples below.

[0034] <Components other than base oil (A) and tertiary amine (B)> The lubricating oil composition of the present embodiment may or may not contain components other than the base oil (A) and the tertiary amine (B) to the extent that the effects of the present invention are not significantly impaired. Examples of the other components include oiliness agents, antioxidants, rust inhibitors, metal deactivators, corrosion inhibitors, extreme pressure agents, antifoaming agents, demulsifiers, and pour point depressants, etc. In addition, these components may or may not further contain dilution oils, dispersants, dispersion aids, etc. as other components for performing at least one of dilution and dispersion. The other components may be used alone or in combination of two or more. In the lubricating oil composition of this embodiment, the total content of other components is preferably 0 mass% to 15 mass%, more preferably 0.1 mass% to 10 mass%, and even more preferably 0.5 mass% to 5 mass%, based on the total amount of the lubricating oil composition.

[0035] (Oil-based agent) Examples of oily agents include aliphatic saturated monocarboxylic acids and aliphatic unsaturated monocarboxylic acids such as stearic acid and oleic acid; polymerized fatty acids such as dimer acid and hydrogenated dimer acid; hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid; aliphatic saturated and unsaturated monoalcohols such as lauryl alcohol and oleyl alcohol; aliphatic saturated and unsaturated monoamines such as stearylamine and oleylamine; aliphatic saturated monocarboxylic acid amides and aliphatic unsaturated monocarboxylic acid amides such as lauric acid amide and oleic acid amide; and partial esters of polyhydric alcohols such as glycerin and sorbitol with aliphatic saturated monocarboxylic acids or aliphatic unsaturated monocarboxylic acids. The oily agents may be used alone or in combination of two or more. The content of the oiliness agent is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 10 mass % or less, more preferably 5 mass % or less.

[0036] (Antioxidants) Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, and sulfur-based antioxidants. The antioxidants may be used alone or in combination of two or more. The content of the antioxidant is preferably 0.01 mass % or more, more preferably 0.05 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 5 mass % or less, more preferably 3 mass % or less.

[0037] (metal deactivator) Examples of the metal deactivator include benzotriazoles, benzimidazoles, benzothiazoles, thiadiazoles, and dimercaptothiazoles. The metal deactivators may be used alone or in combination of two or more. The content of the metal deactivator is preferably 0.005 mass % or more, more preferably 0.01 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 5 mass % or less, more preferably 3 mass % or less.

[0038] (Corrosion inhibitor) Corrosion inhibitors include, for example, alkanolamines, amides, and carboxylic acids. The corrosion inhibitors may be used alone or in combination of two or more. The content of the corrosion inhibitor is preferably 0.005 mass % or more, more preferably 0.01 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 5 mass % or less, more preferably 3 mass % or less.

[0039] (Extreme pressure agent) Examples of the extreme pressure agent include phosphorus-based extreme pressure agents such as phosphate esters, acid phosphate esters, phosphites, and acid phosphites, as well as amine salts thereof, and examples thereof include trithiophenyl phosphate. Other extreme pressure agents include metal salts of carboxylic acids. The metal salts of carboxylic acids mentioned here are preferably metal salts of carboxylic acids having 3 to 60 carbon atoms, more preferably metal salts of fatty acids having 3 to 30 carbon atoms, and even more preferably metal salts of fatty acids having 12 to 30 carbon atoms. In addition, metal salts of the above fatty acid dimer acids, trimer acids, and dicarboxylic acids having 3 to 30 carbon atoms can be mentioned. As the metal salts of carboxylic acids, metal salts of fatty acids having 12 to 30 carbon atoms and dicarboxylic acids having 3 to 30 carbon atoms are preferred. As the metal constituting the metal salt, alkali metals or alkaline earth metals are preferred, and alkali metals are more preferred. Further, examples of extreme pressure agents other than those mentioned above include sulfur-based extreme pressure agents such as sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiocarbamates, thioterpenes, and dialkylthiodipropionates. The extreme pressure agents may be used alone or in combination of two or more. The content of the extreme pressure agent is preferably 0.05 mass % or more, more preferably 0.1 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 10 mass % or less, more preferably 5 mass % or less. In the lubricating oil composition of this embodiment, the content of the acidic phosphate ester may be small. Specifically, the content of the acidic phosphate ester may be less than 1.0 mass%, less than 0.5 mass%, less than 0.1 mass%, less than 0.05 mass%, or less than 0.01 mass% based on the total amount of the lubricating oil composition, and the acidic phosphate ester may not be included.

[0040] (Antifoaming agent) Examples of the defoaming agent include silicone-based defoaming agents such as silicone oil, fluorinated silicone-based defoaming agents such as fluorosilicone oil, and polyacrylates. The antifoaming agent may be used alone or in combination of two or more kinds. The content of the antifoaming agent is preferably 0.0001 mass % or more, more preferably 0.0005 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 0.5 mass % or less, more preferably 0.01 mass % or less.

[0041] (Demulsifier) Examples of the demulsifier include polyalkylene glycols and derivatives thereof; surfactants such as anionic surfactants, cationic surfactants, and nonionic surfactants; and the like. The demulsifier may be used alone or in combination of two or more kinds. The content of the demulsifier is, for example, from 0.001 mass % to 0.5 mass % based on the total amount of the lubricating oil composition. However, since the lubricating oil composition of this embodiment is retained in the water-soluble cutting oil to suppress the proliferation of microorganisms, it is not necessary to improve the separability from the water-soluble cutting oil. Therefore, the content of the demulsifier may be small, preferably less than 0.001 mass%, more preferably less than 0.0001 mass%.

[0042] (Pour point depressants) Examples of pour point depressants include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates (PMA; polyalkyl (meth)acrylates, etc.), polyvinyl acetate, polyalkylstyrene, and the like. The pour point depressants may be used alone or in combination of two or more. The content of the pour point depressant is preferably 0.05 mass % or more, more preferably 0.1 mass % or more, based on the total amount of the lubricating oil composition, and is preferably 1 mass % or less, more preferably 0.5 mass % or less.

[0043] [Physical properties of lubricating oil composition] (40℃ kinematic viscosity, viscosity index) The lubricating oil composition of this embodiment preferably has a kinematic viscosity at 40°C of 9.00mm 2 / s~242mm 2 / s, more preferably 19.8 mm 2 / s~110mm 2 / s, and more preferably 28.8 mm 2 / s~74.8mm 2 / s. The lubricating oil composition of this embodiment preferably has a viscosity index of 100 or greater. In this specification, the 40° C. kinematic viscosity and viscosity index of a lubricating oil composition refer to values ​​measured or calculated in accordance with JIS K2283:2000.

[0044] (Nitrogen atom content) In the lubricating oil composition of this embodiment, the nitrogen atom content, based on the total amount of the lubricating oil composition, is preferably 0.08 mass% to 0.20 mass%, more preferably 0.08 mass% to 0.18 mass%, even more preferably 0.09 mass% to 0.16 mass%, and still more preferably 0.09 mass% to 0.15 mass%. The nitrogen atom content is a value measured by a chemiluminescence method in accordance with JIS K2609:1998.

[0045] [Method of manufacturing lubricating oil composition] The method for producing the lubricating oil composition of this embodiment is not particularly limited. For example, a method for producing a lubricating oil composition of this embodiment includes a step of mixing a base oil (A) with a tertiary amine (B), the tertiary amine (B) having two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members of the cycloalkyl skeletons is each independently 5 or 6, and the number of carbon atoms of the alkyl group is 1 to 3. The method for mixing the above components is not particularly limited, and may be, for example, a method having a step of blending a tertiary amine (B) with a base oil (A). When blending components other than the base oil (A) and the tertiary amine (B), the other components may be blended simultaneously with the tertiary amine (B) or may be blended separately. In addition, each component may be blended after being made into a solution (dispersion) by adding a diluent oil or the like. After blending each component, it is preferable to stir and uniformly disperse them by a known method. In the method for producing the lubricating oil composition of this embodiment, the preferred aspects of the base oil (A) and the tertiary amine (B) are the same as those described above. The preferred range of the blending amount of the tertiary amine (B) is the same as the preferred range of the content of the tertiary amine (B) described above.

[0046] [Uses of lubricating oil composition] The lubricating oil composition of the present embodiment can inhibit the proliferation of microorganisms when the sliding surface lubricating oil composition is contaminated with a water-soluble cutting oil. Therefore, according to the present invention, the following methods of use are provided. A method for using the lubricating oil composition of the present embodiment for inhibiting the proliferation of microorganisms in a water-soluble cutting oil. The present invention also provides the following method. A method for inhibiting the proliferation of microorganisms in water-soluble cutting oil, comprising the steps of mixing the lubricating oil composition of the present embodiment into a water-soluble cutting oil, and then retaining the sliding surface lubricating oil composition in the water-soluble cutting oil without removing it.

[0047] [Machine tools] The lubricating oil composition of the present embodiment can be suitably used as a lubricating oil composition for the sliding surfaces of machine tools. Examples of machine tools that can use the lubricating oil composition of this embodiment include NC (Numerical Control Machine) machine tools, machining centers, grinding machines, CNC (Computerized Numerical Control), multi-tasking machines, and the like. The lubricating oil composition of this embodiment can suppress the proliferation of microorganisms when the lubricating oil composition for sliding surfaces is mixed with the water-soluble cutting oil. Therefore, it is not necessary to separate the lubricating oil composition of this embodiment from the water-soluble cutting oil by a device such as an oil skimmer in a space such as a cutting oil tank where the lubricating oil composition for sliding surfaces is mixed with the water-soluble cutting oil. Therefore, according to the lubricating oil composition of the present embodiment, a machine tool having a mechanism for supplying the lubricating oil composition to a sliding surface is provided.The machine tool can be an NC (Numerical Control Machine) machine tool, a machining center, a grinding machine, a CNC (Computerized Nume), a multitasking machine, etc.The system including the machine tool having a mechanism for supplying the lubricating oil composition to a sliding surface does not need to be equipped with an oil separation device such as an oil skimmer.

[0048] [One aspect of the present invention provided] According to one aspect of the present invention, the following [1] to [8] are provided. [1] A lubricating oil composition for sliding surfaces, comprising a base oil (A) and a tertiary amine (B), The tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members in each of the cycloalkyl skeletons is independently 5 or 6; The alkyl group has 1 to 3 carbon atoms. [2] The lubricating oil composition for sliding surfaces according to the above [1], wherein the tertiary amine (B) comprises one or more compounds selected from the group consisting of compounds represented by the following general formula (1): [ka] [In the general formula (1), each symbol represents the following.] R 1 , R 2 , R 3 each independently represents an alkyl group having 1 to 3 carbon atoms. n1 and n2 each independently represent 0 or 1. When n1 is 0, m1 is an integer of 0 to 9. When n1 is 1, m1 is an integer from 0 to 11. When n2 is 0, m2 is an integer of 0 to 9. When n2 is 1, m2 is an integer from 0 to 11. [3] The sliding surface lubricant oil composition according to the above [2], wherein in the general formula (1), n1 = n2 = 1. [4] The sliding surface lubricant oil composition according to the above [2] or [3], wherein in the general formula (1), m1 = m2 = 0. [5] In the general formula (1), R 1 The lubricating oil composition for sliding surfaces according to any one of the above [2] to [4], wherein is a methyl group. [6] The lubricating oil composition for sliding surfaces according to any one of the above [1] to [5], wherein the content of the tertiary amine (B) is more than 1.00 mass based on the total amount of the lubricating oil composition for sliding surfaces. [7] A method for using the sliding surface lubricant oil composition according to any one of the above [1] to [6] for inhibiting the proliferation of microorganisms in a water-soluble cutting oil. [8] A method for inhibiting the proliferation of microorganisms in a water-soluble cutting oil, comprising the steps of mixing the sliding surface lubricating oil composition according to any one of the above [1] to [6] into a water-soluble cutting oil, and then retaining the sliding surface lubricating oil composition in the water-soluble cutting oil without removing it. [9] A method for producing a lubricant oil composition for sliding surfaces, comprising the step of mixing a base oil (A) and a tertiary amine (B), The tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members in each of the cycloalkyl skeletons is independently 5 or 6; A method for producing a lubricant oil composition for sliding surfaces, wherein the alkyl group has 1 to 3 carbon atoms. EXAMPLES

[0049] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

[0050] [Examples 1 to 3 and Comparative Example 1] The raw materials used in the preparation of the sliding surface lubricating oil compositions of Examples 1 to 3 and Comparative Example 1 are shown below.

[0051] <Base oil (A)> "Mineral oil 1": Mineral oil classified as Group II in the API category (kinematic viscosity at 40°C: 29mm 2 / s) "Mineral oil 2": Mineral oil classified as Group II in the API category (kinematic viscosity at 40°C: 97mm 2 / s) · "Synthetic oil": Polybutene (100℃ kinematic viscosity: 2,850mm 2 / s)

[0052] <Tertiary amine (B)> "N-methyldicyclohexylamine": a tertiary amine having two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom. The cycloalkyl skeletons are cyclohexyl groups, and the alkyl group is a methyl group. Specifically, in the above general formula (1), R 1 is a methyl group, n1 and n2 are 1, and m1 and m2 are 0.

[0053] <Tertiary amine (B')> - "Trioctylamine": A tertiary amine with three octyl groups bonded to the nitrogen atom.

[0054] <Other additives> "Slide surface oil additive package": Amine-based antioxidants, sulfur-based extreme pressure agents, thiophosphates, fatty acid salts, rust inhibitors, dispersing agents, diluents

[0055] The above raw materials were thoroughly mixed in the blending amounts (mass %) shown in Table 1 to prepare slideway lubricant oil compositions of Examples 1 to 3 and Comparative Example 1, respectively.

[0056] [Measurement or evaluation methods for various physical properties] (1) 40℃ kinematic viscosity, viscosity index The 40°C kinematic viscosity and viscosity index were measured in accordance with JIS K2283:2000.

[0057] (2)Nitrogen atom content Measurement was performed by the chemiluminescence method in accordance with JIS K2609:1998.

[0058] (3) Volatilization amount of tertiary amine 20 g of the tertiary amine was placed in a 120 mL container and the weight was measured (initial weight). Next, the tertiary amine placed in the container was heated to 60° C. and held for 1 hour, and then the weight was measured (post-test weight). Then, the amount of volatilization of the tertiary amine (60° C., 1 hour) was calculated by the following formula (f1). Volatilization amount (unit: %) = {(initial weight) - (weight after test)} × 100 / (initial weight of tertiary amine) (f1) The greater the volatilization amount of the tertiary amine, the easier it is to volatilize. Conversely, the smaller the volatilization amount of the tertiary amine, the harder it is to volatilize. In this example, a sample with a volatilization amount of tertiary amine of 10% or less was judged to be acceptable.

[0059] (4) Decay test Into an Erlenmeyer flask, 100 mL of a sample prepared by diluting a water-soluble metalworking oil (Daphne Alphacool EX-1, emulsion type, manufactured by Idemitsu Kosan Co., Ltd.) with water to 5% by volume, and 10 mL each of the sliding surface lubricant oil compositions of Examples 1 to 3 and Comparative Example 1 were placed. 5mL of putrefactive fluid A and 0.5mL of putrefactive fluid B shown below were added, and shake culture was carried out at 30℃ and 150 rpm for 7 days, and the viable cell count was measured. After measuring the viable cell count on the 7th day, 5mL of putrefactive fluid A and 0.5mL of putrefactive fluid B were added, and shake culture was carried out for another 7 days, and the viable cell count was measured. The putrefactive test conditions are shown below. <Conditions for spoilage testing> Culture conditions: 3 g of FC200 dry cuttings were added and the mixture was shaken at 30°C and 150 rpm. In this example, the viable cell count was 10 7 A sliding surface lubricant oil composition that took 3 weeks or longer to reach CFU / mL was rated as passing. Details of putrefactive fluids A and B and the method for measuring the viable bacterial count are given below.

[0060] (Details of putrefactive fluids A and B) ·Septic liquid A The emulsion-type cutting fluid that had decayed and deteriorated was added with Nippon Seiyaku's SCD medium "Daigo" and activated by aeration for 72 hours. ·Septic liquid B The emulsion-type cutting fluid that had decayed and deteriorated was added to the potato dextrose agar medium "Daigo" manufactured by Nippon Seiyaku Co., Ltd., and activated by aeration for 72 hours.

[0061] (Method for measuring viable cell count) The number of bacteria in 1 mL or the degree of bacterial contamination was measured using the Sanai Bioche The viable cell count was measured using a "bacterial count calculator" and displayed according to the following display criteria. The displayed viable cell count was then used to evaluate spoilage resistance based on the evaluation criteria for the spoilage test described above. The number of viable bacteria in 1 mL was measured using TTC medium for bacterial counts on the "Sanai Biochecker" manufactured by Sanai Oil Co., Ltd., and spoilage resistance was evaluated based on the viable bacterial count. Additionally, measurements of yeast and mold were also carried out using M medium for yeast and S medium for mold on the San-Ai Biochecker manufactured by San-Ai Oil Co., Ltd., and it was confirmed that the proliferation of yeast and mold was suppressed within the range of the life span based on the viable cell count of the bacteria.

[0062] The results are shown in Table 1.

[0063] [Table 1]

[0064] From Table 1, we can see the following: From the results shown in Examples 1 to 3, it is understood that the sliding surface lubricant oil composition containing a specific amount of the tertiary amine (B) has an excellent effect of inhibiting the proliferation of microorganisms. It is also understood that the tertiary amine (B) is difficult to volatilize. In contrast, it is found that a lubricating oil composition for sliding surfaces containing a tertiary amine (B') in which all of the groups bonded to the nitrogen atom are straight-chain alkyl groups (octyl groups), as in Comparative Example 1, has insufficient effect in inhibiting the growth of microorganisms.

Claims

1. A sliding surface lubricating oil composition comprising a base oil (A) and a tertiary amine (B), The tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members in each cycloalkyl skeleton is independently 5 or 6; The alkyl group has 1 to 3 carbon atoms.

2. 2. The sliding surface lubricating oil composition according to claim 1, wherein the tertiary amine (B) comprises at least one compound selected from the group consisting of compounds represented by the following general formula (1): [In the general formula (1), each symbol represents the following.] R １ , R ２ , R ３ each independently represents an alkyl group having 1 to 3 carbon atoms. n1 and n2 each independently represent 0 or 1. When n1 is 0, m1 is an integer from 0 to 9. When n1 is 1, m1 is an integer from 0 to 11. When n2 is 0, m2 is an integer from 0 to 9. When n2 is 1, m2 is an integer from 0 to 11.

3. 3. The sliding surface lubricating oil composition according to claim 2, wherein n1 = n2 = 1 in the general formula (1).

4. 4. The sliding surface lubricating oil composition according to claim 2, wherein in said general formula (1), m1 = m2 = 0.

5. In the general formula (1), R １ The sliding surface lubricating oil composition according to claim 2 or 3, wherein is a methyl group.

6. 3. The lubricating oil composition for sliding surfaces according to claim 1, wherein the content of the tertiary amine (B) is more than 1.00 mass percent based on the total amount of the lubricating oil composition for sliding surfaces.

7. 3. A method for using the sliding surface lubricating oil composition according to claim 1 or 2 for inhibiting the growth of microorganisms in a water-soluble cutting oil.

8. 3. A method for inhibiting the growth of microorganisms in a water-soluble cutting oil, comprising the steps of mixing the sliding surface lubricating oil composition according to claim 1 or 2 into the water-soluble cutting oil, and then retaining the sliding surface lubricating oil composition in the water-soluble cutting oil without removing it.

9. A method for producing a sliding surface lubricating oil composition, comprising the step of mixing a base oil (A) and a tertiary amine (B), The tertiary amine (B) has two cycloalkyl skeletons bonded to a nitrogen atom and one alkyl group bonded to a nitrogen atom, the number of ring members in each cycloalkyl skeleton is independently 5 or 6; The alkyl group has 1 to 3 carbon atoms.

Images