JP5473240B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition.

  Lubricating oils for sliding guide surfaces such as processing tables of machine tools are required to have low friction performance, prevention of stick-slip, storage stability, corrosion resistance, and the like in order to improve processing accuracy. In many machine tools, the sliding guide surface lubricant is mixed with the machining fluid of the workpiece. In particular, when a water-soluble cutting fluid is used as the machining fluid, the mixing of the lubricating oil for the sliding guide surface may cause deterioration of the water-soluble cutting fluid (deterioration of cutting performance, acceleration of decay, shortening of mineral oil life, waste liquid treatment cost Is one of the causes. Therefore, as for the performance of the lubricating oil for the sliding guide surface, in addition to excellent lubrication characteristics such as reduction of the friction coefficient on the sliding guide surface and prevention of stick slip, the case where water-soluble cutting fluid is mixed is considered. Therefore, it is required to be excellent in separability from the water-soluble cutting fluid and not to adversely affect various performances of the water-soluble cutting fluid or the sliding guide surface lubricating oil.

Various extreme pressure agents and oil-based agents have been used as friction reducing agents. In recent machine tools, the demand for accuracy is increasing, and in order to reduce friction in the low speed range, which has an important impact on accuracy, phosphate esters, acidic phosphate esters, carboxylic acids, sulfur compounds, amines Etc. are used (see, for example, Patent Documents 1, 2, 3, and 4). In addition, attempts have been made to improve stability by neutralizing acidic phosphate esters with alkylamines (see, for example, Patent Document 5).
JP-A-8-134488 JP 2001-104973 A JP 2003-171684 A JP 2003-430949 A JP 2007-238764 A

  However, in these prior arts, the load of the additive on the environment is high, and although such an additive has excellent initial friction performance and positioning performance of the machine tool, the water-soluble cutting fluid is included in the lubricating oil for the sliding guide surface. If this occurs, the initial low-friction performance will be significantly impaired, and acid components such as phosphoric acid will cause corrosion on the sliding surfaces that use iron. The positioning accuracy tended to deteriorate as usage progressed.

  In the past, attempts have been made to improve stability by neutralizing acidic phosphate esters with alkylamines, but it has been difficult to maintain low friction over a long period of time with conventional additive combinations. . Therefore, there has been a need for an oil agent that can maintain excellent friction performance over a long period of time.

  The present invention has been made in view of such circumstances, and its purpose is excellent in low friction, positioning, thermal stability, low-temperature storage stability, and even when cutting fluid is mixed. Another object of the present invention is to provide a lubricating oil composition that does not significantly deteriorate the low friction property, and also to provide a lubricating oil composition that is excellent in corrosion resistance.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a mixture of a specific acidic phosphate ester and a specific aliphatic amine and / or a reactant in a specific ratio to the lubricating base oil. It has been found that the above problems can be solved by a lubricating oil composition that contains and the acid value derived from the acidic phosphate ester satisfies a specific condition, and has completed the present invention.

［式（１）中、Ｒ^１及びＲ^２は同一でも異なっていてもよく、それぞれ水素原子又は直鎖アルキル基を表し、Ｒ^１及びＲ^２の少なくとも一方は炭素数６〜１２の直鎖アルキル基であり；
式（２）中、Ｒ^３及びＲ^４は同一でも異なっていてもよく、それぞれ水素原子又は直鎖アルケニル基を表し、Ｒ^３及びＲ^４の少なくとも一方は炭素数１３〜１８の直鎖アルケニル基であり；
式（３）中、Ｒ^５及びＲ^６は同一でも異なっていてもよく、それぞれ水素原子又は炭素数６〜１４の分岐鎖アルキル基を表し、Ｒ^５及びＲ^６の少なくとも一方は分岐鎖アルキル基である。］ That is, the lubricating oil composition of the present invention is selected from (A) the following general formula (1) or acidic phosphate ester represented by the following general formula (2) based on the total amount of the lubricating base oil and the composition. And / or a reaction product (the above-mentioned reaction product ) of 0.1 to 0.4 % by mass of (B) and 0.1 to 0.5 % by mass of alkylamine represented by the following general formula (3) contains the unreacted (a) including the component.), (a) the acid value derived from the component 0.1~1.0mgKOH / g der is, used in the slideways of a machine tool It is characterized by that.

[In Formula (1), R ¹ and R ² may be the same or different and each represents a hydrogen atom or a linear alkyl group , and at least one of R ¹ and R ² is a linear alkyl having 6 to 12 carbon atoms. A group ;
In formula (2), R ³ and R ⁴ may be the same or different and each represents a hydrogen atom or a linear alkenyl group , and at least one of R ³ and R ⁴ is a linear alkenyl group having 13 to 18 carbon atoms. Is;
In formula (3) , R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a branched alkyl group having 6 to 14 carbon atoms, and at least one of R ⁵ and R ⁶ is a branched alkyl group. It is. ]

  The lubricating oil composition of the present invention preferably further contains 0.01 to 5% by mass of (C) a sulfur compound based on the total amount of the composition.

  According to the lubricating oil composition of the present invention, it is excellent in low friction, positioning, thermal stability and low-temperature storage stability, and even when a cutting fluid is mixed, the initial low friction is not significantly deteriorated. In addition, it is possible to maintain the processing accuracy, and furthermore, the corrosion resistance is excellent. Therefore, the lubricating oil composition of the present invention is very useful in terms of stabilizing the operation of the machine tool and extending the life.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  There are no particular restrictions on the method for producing the mineral base oil that can be used in the present invention. For example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation is subjected to solvent removal, solvent extraction, hydrogenation. List paraffinic or naphthenic mineral oils obtained by applying a suitable combination of one or more purification means such as hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment. Can do. Moreover, fats and oils and / or synthetic oil can also be mix | blended with the lubricating base oil of this application.

  Examples of fats and oils include beef tallow, lard, soybean oil, rapeseed oil, rice bran oil, coconut oil, palm oil, palm kernel oil, and hydrogenated products thereof.

  Synthetic oils include, for example, poly-α-olefins (ethylene-propylene copolymers, polybutenes, 1-octene oligomers, 1-decene oligomers, and hydrides thereof), alkylbenzenes, alkylnaphthalenes, monoesters (butyl stearate). Rate, octyl laurate, etc.), diester (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sepacate, etc.), polyester (trimellitic acid ester, etc.), polyol ester (Trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkyl Glycol, polyphenyl ether, dialkyl diphenyl ether, phosphate ester (tricresyl phosphate, etc.), fluorine-containing compound (perfluoropolyether, such as fluorinated polyolefins), such as silicone oil can be exemplified.

  In the lubricating base oil of the present invention, one of the above-described oils and / or synthetic oils may be used alone or in combination of two or more.

The viscosity of the base oil used in the present invention is not particularly limited, preferably has kinematic viscosity at 40 ° C. is in the range of 10~700mm ² / s, it is more preferably in the range of 15~500mm ² / s. Further, the content of the base oil is not particularly limited, but is preferably in the range of 50 to 99.98% by mass based on the total amount of the composition.

［式（１）中、Ｒ^１及びＲ^２は同一でも異なっていてもよく、それぞれ水素原子又は直鎖アルキル基又は直鎖アルケニル基を表し、Ｒ^１及びＲ^２の少なくとも一方は炭素数６〜１２の直鎖アルキル基又は直鎖アルケニル基である。］

［式（２）中、Ｒ^３及びＲ^４は同一でも異なっていてもよく、それぞれ水素原子又は直鎖アルキル基又は直鎖アルケニル基を表し、Ｒ^３及びＲ^４の少なくとも一方は炭素数１３〜１８の直鎖アルキル基又は直鎖アルケニル基である。］ The component (A) is specifically a compound represented by the following general formula (1) and general formula (2).

[In Formula (1), R ¹ and R ² may be the same or different and each represents a hydrogen atom, a linear alkyl group or a linear alkenyl group, and at least one of R ¹ and R ² has 6 to 6 carbon atoms. 12 straight-chain alkyl groups or straight-chain alkenyl groups. ]

[In Formula (2), R ³ and R ⁴ may be the same or different and each represents a hydrogen atom, a linear alkyl group, or a linear alkenyl group, and at least one of R ³ and R ⁴ has from 13 to 13 carbon atoms. 18 straight chain alkyl groups or straight chain alkenyl groups. ]

Specific examples of the linear alkyl group or linear alkenyl group for R ¹ and R ² include a linear hexyl group, a linear hexenyl group, a linear heptyl group, a linear heptenyl group, a linear octyl group, and a linear chain. Octenyl group, linear nonyl group, linear nonenyl group, linear decyl group, linear decenyl group, linear undecyl group, linear undecenyl group, linear dodecyl group, straight acid dodecenyl group, and R ³ and R ⁴ Specific examples of the alkyl group or linear alkenyl group include a linear tridecyl group, a linear tridecenyl group, a linear tetradecyl group, a linear tetradecenyl group, a linear pentadecyl group, a linear pentadecenyl group, and a linear hexadecyl group. Linear hexadecenyl group, linear heptadecyl group, linear heptadecenyl group, linear octadecyl group, linear octadecenyl group, oleyl group and the like.

In (A) acidic phosphate ester used in the present invention, one of R ¹ and R ² in the general formula (1) or R ³ and R ^{4 in} the general formula (2) is a hydrogen atom. And the other is a straight-chain alkyl group or a straight-chain alkenyl group (phosphate monoester), and both R ¹ and R ² or R ³ and R ⁴ are straight-chain alkyl groups and / or straight-chain alkenyl groups. Certain compounds (phosphate diesters) are included. In the present invention, either phosphoric acid monoester or phosphoric acid diester may be used alone, or a mixture of phosphoric acid monoester and phosphoric acid diester may be used. It is preferable to use a mixture of monoester and phosphoric acid diester. When the mixture is used, the mixing ratio of phosphoric acid monoester / phosphoric diester is preferably 10/90 to 90/10 in molar ratio, more preferably 20/80 to 80/20, and 30/70. More preferably, it is -70/30.

  In the lubricating oil composition of the present invention, the content of the (A) acidic phosphate ester is 0.01 to 0.5% by mass based on the total amount of the composition, and the total amount of the composition is more excellent in low friction performance. On the basis, it is preferably 0.05% by mass or more, more preferably 0.1% by mass or more. In addition, the content of the acidic phosphate ester is 0.5% by mass or less, preferably 0.4% by mass or less, based on the total amount of the composition from the viewpoint of further excellent corrosion resistance of the resulting lubricating oil composition. It is. Further, the content of the component (A) in terms of phosphorus element varies depending on the molecular weight of the component (A), but on the basis of the total amount of the composition, in terms of phosphorus element, preferably 0.0005 to 0.06% by mass. More preferably, it is 0.003-0.06 mass%, Most preferably, it is 0.005-0.05 mass.

  In the lubricating oil composition of the present invention, the acid value derived from the component (A) is 0.1 to 1.0 mgKOH / g, and if it is less than 0.1 mgKOH / g, it is preferable because the friction reducing effect of the additive is low. In addition, the corrosion of the sliding material exceeding 1.0 mgKOH / g increases, and the friction performance is not preferable because low friction cannot be maintained over a long period of time.

The component (B) in the present invention is an alkylamine represented by the following general formula (3).

In formula (3), R ⁵ and R ⁶ may be the same or different and each is a hydrogen atom or a branched alkyl group having 4 to 30 carbon atoms, and at least one of R ⁵ and R ⁶ is a branched alkyl group. It is. Usually, the amine represented by the formula (3) may be any of monoamine, diamine, and polyamine having 1 or 2 or more branched alkyl groups having 4 to 30 carbon atoms, preferably 4 to 20 carbon atoms. Although good, the monoamine which has a C4-C20 branched alkyl group is preferable, and the monoamine secondary amine which has two C4-C20 branched alkyl groups is preferable. Among these branched chain alkyl groups, the carbon number of these branched chain alkyl groups is 6 or more from the viewpoint of excellent low temperature storage stability when mixed with component (A) and low friction performance when mixed with cutting oil. More preferably. Further, from the viewpoint of solubility in the lubricating base oil, the carbon number of these branched chain alkyl groups is preferably 20 or less, more preferably 16 or less, and even more preferably 14 or less.

  Specific examples of the preferable branched alkyl group having 4 to 20 carbon atoms include isobutyl, isopentyl, isohexyl, isooctyl, isononyl, isodecyl, isoundecyl, isododecyl, isotridecyl, isotetradecyl, Examples thereof include branched alkyl groups such as a decyl group, an isopentadecyl group, an isohexadecyl group, an isoheptadecyl group, an isooctadecyl group, an isononadecyl group, and an isoicosyl group.

  In the lubricating oil composition of the present invention, the content of the (B) alkylamine is 0.01 to 2% by mass based on the total amount of the composition, and the corrosion resistance when mixed with the component (A) is further improved. From the total amount of the composition, it is preferably 0.05% by mass or more, particularly preferably 0.1% by mass or more. Moreover, from the point which is further excellent in low temperature storage stability and the low friction performance when cutting oil is mixed, the content of the component (B) is 2% by mass or less, more preferably 1%, based on the total amount of the composition. 0.0 mass% or less, particularly preferably 0.5 mass% or less. Further, the content of the component (B) in terms of nitrogen element is different depending on the molecular weight of the component (B), but on the basis of the total amount of the composition, in terms of nitrogen element, preferably 0.0002 to 0.4 mass%. More preferably, it is 0.001-0.2 mass%, Most preferably, it is 0.002-0.1 mass%.

  In the lubricating oil composition of the present invention, the optimum combination of the component (A) and the component (B) is an acidic phosphate ester having a linear alkyl group having 6 to 18 carbon atoms and a carbon number having 4 to 30 carbon atoms. In combination with amines having branched alkyl groups, in particular mono-n-octyl acid phosphate and / or di-n-octyl acid phosphate or monooleyl acid phosphate and / or dioleyl acid phosphate and di-2-ethylhexylamine and A combination of / or diisotridecylamine is most preferred.

  The lubricating oil composition of the present invention contains the component (A) and the component (B) having the above-described configuration, or a configuration comprising the lubricating base oil and the components (A) and (B) having the above-described configuration. In addition, it has excellent low-friction properties and low-temperature storage stability, and even when cutting fluid is mixed, it is possible to maintain machining accuracy without significantly deteriorating the initial low-friction properties. It is preferable to contain a sulfur compound in that it is excellent in that the friction coefficient can be kept lower and the processing accuracy can be maintained over a long period of time.

  (C) component of this invention is a sulfur compound. Component (C) is a sulfur compound that has a sulfur atom in the molecule and can be dissolved or uniformly dispersed in the lubricating base oil so that the lubricating oil composition can exhibit extreme pressure properties and excellent friction characteristics. I just need it.

  Examples of the sulfur compound of component (C) include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiadiazole compounds, alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, dialkylthiodipropionate compounds, and the like. be able to. Such compounds may be used alone or as a mixture of two or more.

  Here, the sulfurized fats and oils are obtained by reacting sulfur and sulfur-containing compounds with fats and oils (lard oil, whale oil, vegetable oil, fish oil, etc.), and the sulfur content is not particularly limited, but generally 5 to 30. The thing of the mass% is suitable. Specific examples thereof include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil, sulfurized rice bran oil, and mixtures thereof.

  Examples of sulfurized fatty acids include sulfurized oleic acid, and examples of sulfurized esters include sulfurized methyl oleate, sulfurized rice bran fatty acid octyl, and mixtures thereof.

As the sulfurized olefin, for example, the following general formula (4):
R ⁷ -S _a -R ⁸ (4)
[In formula (4), R ⁷ represents an alkenyl group having 2 to 15 carbon atoms, R ⁸ represents an alkyl group or alkenyl group having 2 to 15 carbon atoms, and a represents an integer of 1 to 8]
The compound etc. which are represented by these can be mentioned. This compound is obtained by reacting an olefin having 2 to 15 carbon atoms or a dimer to tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride, and propylene, isobutene, diisobutene and the like are preferable.

Dihydrocarbyl polysulfide is represented by the following general formula (5):
R ⁹ -S _b -R ¹⁰ (5)
[In Formula (5), R ⁹ and R ¹⁰ are each an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or 7 carbon atoms. To 20 arylalkyl groups, which may be the same or different from each other, and b represents an integer of 1 to 8]
It is a compound represented by these. Here, when R ⁹ and R ¹⁰ are alkyl groups, they are called alkyl sulfides.

Specific examples of R ⁹ and R ¹⁰ in the general formula (5) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, Various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl groups, cyclooctyl groups, phenyl groups, naphthyl groups, tolyl groups, xylyl groups, benzyl groups, Examples thereof include a phenethyl group.

  Preferred examples of the dihydrocarbyl polysulfide include dibenzyl polysulfide, various dinonyl polysulfides, various didodecyl polysulfides, various dibutyl polysulfides, various dioctyl polysulfides, diphenyl polysulfide, dicyclohexyl polysulfide, and mixtures thereof.

［式中、Ｒ^１１およびＲ^１２は、それぞれ水素原子、炭素数１〜２０の炭化水素基を示し、ｃおよびｄは、それぞれ０〜８の整数を示す）
で表される１，３，４−チアジアゾール、１，２，４−チアジアゾール化合物、１，４，５−チアジアゾールなどが好ましく用いられる。このようなチアジアゾール化合物の具体例としては、２，５−ビス（ｎ−ヘキシルジチオ）−１，３，４−チアジアゾール、２，５−ビス（ｎ−オクチルジチオ）−１，３，４−チアジアゾール、２，５−ビス（ｎ−ノニルジチオ）−１，３，４−チアジアゾール、２，５−ビス（１，１，３，３−テトラメチルブチルジチオ）−１，３，４−チアジアゾール、３，５−ビス（ｎ−ヘキシルジチオ）−１，２，４−チアジアゾール、３，５−ビス（ｎ−オクチルジチオ）−１，２，４−チアジアゾール、３，５−ビス（ｎ−ノニルジチオ）−１，２，４−チアジアゾール、３，５−ビス（１，１，３，３−テトラメチルブチルジチオ）−１，２，４−チアジアゾール、４，５−ビス（ｎ−ヘキシルジチオ）−１，２，３−チアジアゾール、４，５−ビス（ｎ−オクチルジチオ）−１，２，３−チアジアゾール、４，５−ビス（ｎ−ノニルジチオ）−１，２，３−チアジアゾール、４，５−ビス（１，１，３，３−テトラメチルブチルジチオ）−１，２，３−チアジアゾールおよびこれらの混合物などを好ましく挙げることができる。 Examples of the thiadiazole compound include the following general formulas (6), (7) and (8):

[Wherein, R ¹¹ and R ¹² each represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and c and d each represent an integer of 0 to 8)
1,3,4-thiadiazole, 1,2,4-thiadiazole compound, 1,4,5-thiadiazole and the like are preferably used. Specific examples of such thiadiazole compounds include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole, 2,5-bis (n-octyldithio) -1,3,4-thiadiazole. 2,5-bis (n-nonyldithio) -1,3,4-thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole, 3, 5-bis (n-hexyldithio) -1,2,4-thiadiazole, 3,5-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n-nonyldithio) -1 , 2,4-thiadiazole, 3,5-bis (1,1,3,3-tetramethylbutyldithio) -1,2,4-thiadiazole, 4,5-bis (n-hexyldithio) -1,2 , 3-thiadiazole, 4 5-bis (n-octyldithio) -1,2,3-thiadiazole, 4,5-bis (n-nonyldithio) -1,2,3-thiadiazole, 4,5-bis (1,1,3,3) Preferred examples include -tetramethylbutyldithio) -1,2,3-thiadiazole and a mixture thereof.

［式中、Ｒ^１３〜Ｒ^１６は、それぞれ炭素数１〜２０のアルキル基を示し、ｅは１〜８の整数を示す］
で表される化合物が挙げられる。このようなアルキルチオカルバモイル化合物の具体例としては、ビス（ジメチルチオカルバモイル）モノスルフィド、ビス（ジブチルチオカルバモイル）モノスルフィド、ビス（ジメチルチオカルバモイル）ジスルフィド、ビス（ジブチルチオカルバモイル）ジスルフィド、ビス（ジアミルチオカルバモイル）ジスルフィド、ビス（ジオクチルチオカルバモイル）ジスルフィドおよびこれらの混合物などを好ましく挙げることができる。 Examples of the alkylthiocarbamoyl compound include the following general formula (9):

[Wherein, R ^{13 to} R ¹⁶ each represent an alkyl group having 1 to 20 carbon atoms, and e represents an integer of 1 to 8]
The compound represented by these is mentioned. Specific examples of such alkylthiocarbamoyl compounds include bis (dimethylthiocarbamoyl) monosulfide, bis (dibutylthiocarbamoyl) monosulfide, bis (dimethylthiocarbamoyl) disulfide, bis (dibutylthiocarbamoyl) disulfide, and bis (diamil). Preferred examples include thiocarbamoyl) disulfide, bis (dioctylthiocarbamoyl) disulfide, and mixtures thereof.

［式中、Ｒ^１３〜Ｒ^１６は、それぞれ炭素数１〜２０のアルキル基を示し、Ｒ^１７は炭素数１〜１０のアルキル基を示す］
で示される化合物が挙げられる。このようなアルキルチオカーバメート化合物の具体例としては、メチレンビス（ジブチルジチオカーバメート）、メチレンビス［ジ（２−エチルヘキシル）ジチオカーバメート］などを好ましく挙げることができる。 Examples of the alkylthiocarbamate compound include the following general formula (10):

[Wherein R ^{13 to} R ¹⁶ each represent an alkyl group having 1 to 20 carbon atoms, and R ¹⁷ represents an alkyl group having 1 to 10 carbon atoms]
The compound shown by these is mentioned. Preferable examples of such alkylthiocarbamate compounds include methylenebis (dibutyldithiocarbamate), methylenebis [di (2-ethylhexyl) dithiocarbamate] and the like.

  Further, examples of the thioterpene compound include a reaction product of phosphorus pentasulfide and pinene, and examples of the dialkylthiodipropionate compound include dilauryl thiodipropionate, distearyl thiodipropionate, and a mixture thereof. be able to.

  In the lubricating oil composition of the present invention, the content of the component (C) is preferably 0.01% by mass or more based on the total amount of the composition from the viewpoint of the friction characteristics of the resulting lubricating oil composition. The content is more preferably 05% by mass or more, and still more preferably 0.1% by mass or more. In addition, since the obtained lubricating oil composition is more excellent in separability from the water-soluble cutting fluid, and further improvement in friction characteristics may not be expected even if it is further contained, the content of the component (C) is It is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less based on the total amount of the composition.

  In order to further improve the performance of the lubricating oil composition of the present invention or to provide performance necessary as a lubricating oil composition for various applications, particularly as a lubricating oil composition for sliding surfaces of machine tools, Additives known in the art can be blended.

  Examples of such additives include monohydric alcohol or polyhydric alcohol, monobasic acid or polybasic acid, esters of the alcohol and the acid, amines other than claim 1, amine compounds such as amine compounds such as alkanolamine, and the like. Of phenolic compounds such as oxidants, di-tert-butyl-p-cresol, bisphenol A, amine compounds such as phenyl-α-naphthylamine, N, N′-di (2-naphthyl) -p-phenylenediamine, etc. Inhibitors; Metal deactivators such as benzotriazole and alkylthiadiazole; Antifoaming agents such as silicone oil and fluorosilicone oil; Phosphoric additives other than acidic phosphates (normal phosphates, phosphites, acidic (Amine) Phosphate ester amine salts, etc.) Carboxylic acid oils, etc .; Rust prevention additives such as rate; Pour point depressants such as polymethacrylate; Viscosity index improvers such as polymethacrylate, polybutene, polyalkylstyrene, olefin copolymer, styrene-diene copolymer, styrene-maleic anhydride copolymer, etc. .

  The lubricating oil composition of the present invention having the above structure is excellent in low friction performance and low temperature storage stability, and does not significantly deteriorate the initial low friction even when the cutting fluid is mixed. Has excellent corrosion resistance. Therefore, it is suitably used in various applications in the field of lubricating oils that require low friction, low-temperature storage stability and corrosion resistance. In particular, the effect of the present invention is further exhibited when used as a lubricant for a sliding guide surface (sliding surface) of a machine tool or the like.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Examples 1-8, Comparative Examples 1-4]
Various lubricating oil compositions according to the present invention having compositions as shown in Tables 1 and 2 and comparative lubricating oil compositions as shown in Comparative Examples 1 to 4 were prepared. The components used for the preparation of each composition are as follows. In addition, the viscosity index as used in the field of this invention means the viscosity index measured based on JISK2283-1993. In addition, the saturated hydrocarbon component content is defined as “Analytical Chemistry Vol. 44, No. 6 (1972) pp. 915-919” In accordance with the silica-alumina gel chromatographic analysis method described in “Columns”, but in this method, it is fractionated by a method using n-hexane instead of n-pentane used for elution of a saturated hydrocarbon component. The percentage by mass of the saturated hydrocarbon component with respect to the total amount of the sample.
Lubricating base oil:
Base oil 1: (viscosity index: 101, sulfur content: 0.51% by mass, saturated hydrocarbon content: 65.6% by volume, kinematic viscosity at 40 ° C .: 68.7 mm ² / s, flash point: 248 ° C., 15 Density at 0 ° C .: 0.882 g / cm ³ )
(A) Acidic phosphate ester:
A1: Mixture of mono n-octyl acid phosphate and di n-octyl acid phosphate (phosphorus content: 11.6% by mass)
A2: Mixture of monooleyl acid phosphate and dioleyl acid phosphate (phosphorus content: 6.6% by mass)
A3: Mono n-hexyl acid phosphate (phosphorus content: 17% by mass)
A4: Mixture of mono-2-ethylhexyl acid phosphate and di-2-ethylhexyl acid phosphate (phosphorus content: 12.0% by mass)
(B) Alkylamine:
B1: di-2-ethylhexylamine B2: diisotridecylamine B3: 2-ethylhexylamine B4: oleylamine (C) sulfur compound:
C1: Polysulfide (sulfur content: 22.0% by mass)
C2: Sulfurized oil (sulfur content: 11.4% by mass).

  Next, the following tests were performed on the lubricating oil compositions of Examples 1 to 8 and Comparative Examples 1 to 4.

(Frictional property evaluation test)
FIG. 1 is a schematic configuration diagram showing a friction coefficient measurement system used in a friction characteristic evaluation test. In FIG. 1, a table 1 and a movable jig 4 connected via a load cell 5 are arranged on a bed 6, and a heavyweight 9 as a substitute for a processing tool is arranged on the table 1. Yes. Both the table 1 and the bed 6 are made of cast iron. The movable jig 4 has a bearing portion, and the bearing portion is connected to the A / C servo motor 2 via the feed screw 3. By operating the feed screw 3 by the A / C servometer 2, the movable jig 4 can be reciprocated in the axial direction of the feed screw 3 (arrow direction in the figure). Further, the load cell 5 is electrically connected to the computer 7, and the computer 7 and the A / C servometer 2 are electrically connected to the control plate 8, thereby controlling the reciprocating motion of the movable jig 4 and the table 1 and the movable jig. The load between 4 can be measured.
In such a friction coefficient measurement system, a lubricating oil composition is dropped on the upper surface of the bed 6, the surface pressure between the table 1 and the bed 6 is adjusted to 200 kPa by selecting the table weight 9, and then the feed rate is 0.1 mm. The movable jig 4 was reciprocated with a feed length of 15 mm / min. The load between the table 1 and the movable jig 4 at this time is measured by a load cell 5 (load meter), and the friction coefficient of the guide surface (table 1 / bed 6 = cast iron / cast iron) based on the obtained measurement value. Asked. In addition, the said test was done after running in 3 times. The friction coefficient of each lubricating oil composition is shown in Tables 1 and 2.

(Frictional property evaluation test when cutting oil is mixed)
500 mL of a lubricating oil composition and 25 mL of a water-soluble cutting fluid (emulsion-type cutting fluid, manufactured by Nippon Oil Corporation, JIS K2241 “Cutting fluid” equivalent to No. 1 type, dilution factor 10 times) were collected in a 1000 mL beaker. . In a beaker, gently stir with a magnetic rotor for 1 minute at room temperature. The mixture was allowed to stand for 1 hour after stirring, and the upper layer was used as a measurement sample. Tables 1 and 2 show the results of the friction characteristic evaluation test. If the friction coefficient when mixed with cutting oil exceeds 0.110, it is out of the allowable range (×), if it is 0.110 or less, it is within the allowable range (◯), and if it is 0.09 or less, it is extremely excellent (◎ ).

(Phosphorus residual rate when cutting fluid is mixed)
500 mL of a lubricating oil composition and 25 mL of a water-soluble cutting fluid (emulsion-type cutting fluid, manufactured by Nippon Oil Corporation, JIS K2241 “Cutting fluid” equivalent to No. 1 type, dilution factor 10 times) were collected in a 1000 mL beaker. . In a beaker, gently stir with a magnetic rotor for 1 minute at room temperature. After stirring, the mixture was allowed to stand for 1 hour, and the upper layer (oil layer) was used as a measurement sample. Based on JPI test method 5S-38-03 "Lubricating oil-added element test method-inductively coupled plasma emission spectroscopy" of the Japan Petroleum Institute Quantitative analysis of the minute was performed. (Phosphorus content before test / phosphorus content after test) X100 was calculated and used as the phosphorus residual rate (%). The obtained results are shown in Tables 1 and 2.

(Corrosion resistance test when mixed with cutting fluid)
500 mL of a lubricating oil composition and 25 mL of a water-soluble cutting fluid (emulsion-type cutting fluid, manufactured by Nippon Oil Corporation, JIS K2241 “Cutting fluid” equivalent to No. 1 type, dilution factor 10 times) were collected in a 1000 mL beaker. . Gently stirred with a magnetic rotor for 1 minute in a beaker at room temperature. After stirring, the mixture was allowed to stand for 1 hour, used as a measurement sample, 200 ml was collected in a glass beaker, and 7 cm square SPC material (thickness 0.2 mm, No. 80 dull finish) degreased with methanol was immersed in a container at room temperature. After the 20-day specimen was washed with a solvent, the appearance was visually observed and the corrosion resistance was evaluated by the presence or absence of discoloration at the gas-liquid boundary. The evaluation criteria are as follows. The obtained results are shown in Tables 1 and 2.
○: No discoloration △: Slightly discolored ×: Clearly discolored

  As is clear from the results shown in Tables 1 and 2, the lubricating oil compositions of Examples 1 to 8 have a low friction performance (low friction coefficient) compared to the compositions of Comparative Examples 1 to 4, It can be seen that even when cutting oil is mixed, the low friction performance can be maintained and the corrosion resistance can be satisfied.

It is a schematic block diagram which shows the friction coefficient measuring system used in the Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Table, 2 ... A / C servo meter, 3 ... Feed screw, 4 ... Movable jig, 5 ... Load cell, 6 ... Bed, 7 ... Computer, 8 ... Control panel, 9 ... Heavyweight.

Claims (2)

Lubricating base oil, and
Based on the total amount of the composition, (A) at least one selected from acidic phosphates represented by the following general formula (1) or the following general formula (2): 0.1 to 0.4 % by mass; and (B) Containing a mixture and / or a reaction product of 0.1 to 0.5 % by mass of an alkylamine represented by the following general formula (3) (the reaction product contains the unreacted component (A)), and (a) the acid value derived from the component Ri 0.1~1.0mgKOH / g der lubricating oil composition characterized Rukoto used in slideways of a machine tool.

[In Formula (1), R ¹ and R ² may be the same or different and each represents a hydrogen atom or a linear alkyl group , and at least one of R ¹ and R ² is a linear alkyl having 6 to 12 carbon atoms. A group ;
In formula (2), R ³ and R ⁴ may be the same or different and each represents a hydrogen atom or a linear alkenyl group , and at least one of R ³ and R ⁴ is a linear alkenyl group having 13 to 18 carbon atoms. Is;
In formula (3) , R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a branched alkyl group having 6 to 14 carbon atoms, and at least one of R ⁵ and R ⁶ is a branched alkyl group. It is. ]   The lubricating oil composition according to claim 1, further comprising (C) 0.01 to 5% by mass of a sulfur compound based on the total amount of the composition.

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