JP4870452B2 - Lubricating oil composition - Google Patents

Description

  The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition that is suitably used for a machine tool, particularly a sliding guide surface of a machine tool.

  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.

Regarding prevention of stick-slip, for example, a lubricating oil composition in which a sulfur compound, an ester and a fatty acid are combined (see, for example, Patent Document 1), and a lubricating oil composition in which a sulfur compound and an amine salt of a phosphorus compound are combined ( For example, use of patent document 2) etc. is proposed. Regarding friction characteristics, for example, a lubricating oil composition (for example, see Patent Document 3) in which an acidic phosphate ester or an alkylammonium salt thereof, phosphorous acid, a fatty acid and a linear alkylamine are combined, a phosphorus compound is used. Lubricating oil composition for sliding guide surfaces (for example, see Patent Document 4), machine tool oil composition in which a glyceryl ether compound and a phosphate ester or an amine salt thereof are combined (for example, see Patent Document 5) The use of is proposed. In addition, as for separability from the water-soluble cutting fluid, for example, a lubricating oil composition in which carboxylic acid and / or ester, organic acid salt of alkali metal, and phosphite and its amine salt are combined (for example, patent document) 6), a lubricating oil composition in which a carboxylic acid and / or ester, an organic acid salt of an alkali metal, and a phosphate ester are combined (see, for example, Patent Document 7) has been proposed. In addition, a lubricant composition containing an acidic phosphate ester, a specific saturated fatty acid, and further a sulfur-based extreme pressure agent as a material that achieves a good balance of stick-slip prevention, friction characteristics and separability from water-soluble cutting fluid. A thing (for example, refer patent document 8) is proposed.
JP 57-67693 A Japanese Patent Laid-Open No. 51-74005 JP-A-8-134488 JP-A-8-209175 JP-A-11-209775 Japanese Patent Laid-Open No. 9-328696 JP-A-11-1693 JP 2005-187646 A

  However, these prior arts do not sufficiently study the adverse effects of water-soluble cutting fluid mixed in the sliding guide surface lubricating oil. That is, according to the study by the present inventors, when a water-soluble cutting fluid is mixed in the sliding guide surface lubricating oil, the original low friction performance is remarkably impaired, and the machining accuracy in the machine tool is deteriorated. It was found that if corrosion resistance and low-temperature storage stability were not fully taken into consideration, even if the initial performance was excellent, the service life was short, leading to an increase in waste oil.

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

As a result of intensive studies to achieve the above object, the inventors of the present invention have a lubricating base oil containing a specific acidic phosphate ester and a specific aliphatic amine in a predetermined ratio, and further a polyalkylene glycol. The present inventors have found that the above-mentioned problems can be solved by a lubricating oil composition containing a base compound, and have completed the present invention.

［式中、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炭素数８〜２２の炭化水素基を表し、Ｒ ^１ 及びＲ ^２ の少なくとも一方は炭化水素基である。］
また、本発明の潤滑油組成物は各種用途に使用可能であるが、工作機械に用いられることが好ましく、工作機械のすべり案内面に使用されることが特に好ましい。
That is, the lubricating oil composition of the present invention comprises (A) an acidic phosphate ester represented by the following general formula (1) and (B) an aliphatic amine, and / or (A) the following general oil. The reaction product of the acidic phosphate represented by the formula (1) and the (B) aliphatic amine is converted into the amount of phosphorus (P) derived from the component (A) and the amount of nitrogen derived from the component (B) (N). And (A) the acidic phosphate is a mixture of a phosphate monoester and a phosphate diester, and the former and the latter are mixed. The molar ratio is 10/90 to 90/10, the (B) aliphatic amine is a primary amine and / or a secondary amine, and further contains (C) a polyalkylene glycol compound. The lubricating oil composition is as follows.

[Wherein, R ¹ and R ² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 8 to 22 carbon atoms, and at least one of R ¹ and R ² is a hydrocarbon group. ]
The lubricating oil composition of the present invention can be used for various applications, but is preferably used for a machine tool, and particularly preferably used for a sliding guide surface of a machine tool.

  According to the lubricating oil composition of the present invention, it is excellent in low friction and low-temperature storage stability, and even when a cutting fluid is mixed, it is possible to maintain machining accuracy without significantly deteriorating the initial low friction. Furthermore, it is excellent in corrosion resistance. 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 is no restriction | limiting in particular as lubricating base oil in the lubricating oil composition of this invention, For example, at least 1 sort (s) chosen from mineral oil, fats and oils, and synthetic oil can be illustrated.

  Examples of mineral oil base oils that can be used in the present invention include solvent desorption, solvent extraction, hydrocracking, solvent dewaxing for lubricating oil fractions obtained by atmospheric and vacuum distillation of crude oil. And paraffinic or naphthenic mineral oils obtained by appropriately combining one or more purification means such as catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment.

  Examples of the 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, 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.), polyoxy Ruki 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 oil composition of the present invention, one of the above-described base 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.

  In the lubricating oil composition of the present invention, the component (A) is an acidic phosphate ester, the component (B) is an aliphatic amine, and the phosphorus amount (P) (mass%) derived from the component (A) ( B) It is necessary to make it contain in a lubricating oil composition so that ratio (P / N ratio) with nitrogen amount (N) (mass%) resulting from a component may be 4-100. Although this ratio changes with phosphorus content of (A) component, and nitrogen content of (B) component, it means that the ratio of (B) component with respect to (A) component is small, for example. The P / N ratio is preferably 90 or less, more preferably 70 or less, still more preferably 50 or less, still more preferably 30 or less, still more preferably 15 or less, and particularly preferably 10 or less, in terms of superior corrosion resistance. In addition, it is 4 or more, preferably 4.5 or more, more preferably 5 or more, particularly preferably 5.5 or more, from the viewpoint of excellent low-temperature storage stability and low friction performance when mixed with cutting oil. In addition, as long as (A) component and (B) component are contained in the lubricating oil composition in the above specific ratio, they may be contained separately, or may be premixed or reacted (for example, in the form of salt) ) May be contained, but it is preferable that they are premixed or reacted in advance because stable low friction performance can be obtained and low temperature storage stability is excellent.

［式中、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炭素数８〜２２の炭化水素基を表し、Ｒ^１及びＲ^２の少なくとも一方は炭化水素基である。］
Specifically, the component (A) is a compound represented by the following general formula (1).

[Wherein, R ¹ and R ² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 8 to 22 carbon atoms, and at least one of R ¹ and R ² is a hydrocarbon group. ]

Represented by R ¹ and R ^2, examples of the hydrocarbon group having 8 to 22 carbon atoms, A alkyl group, alkenyl group, cycloalkyl group, alkylcycloalkyl group, an aryl group, an alkylaryl group, an arylalkyl group (these The alkyl group or alkenyl group may be linear or branched, and the position of the double bond and the substitution position of the alkyl group to the aryl group or cycloalkyl group are arbitrary.

Among these hydrocarbon groups, from the viewpoint of excellent low friction performance, preferably an alkyl group or an alkenyl group having a carbon number of 8-22, from the viewpoint of more excellent low friction performance, these alkyl and alkenyl group having a carbon The number is preferably 10 or more, more preferably 12 or more, and still more preferably 16 or more. Further, from the viewpoint of solubility in the lubricating base oil, the number of carbon atoms in the alkyl group and the alkenyl group is good preferable is 1 to 8. Furthermore, the alkyl group and the alkenyl group may be either linear or branched, but are preferably linear from the viewpoint of low friction performance, and are further linear alkenyl groups. preferable.

Specific examples of the preferable alkyl group or alkenyl group having 8 to 22 carbon atoms include octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group. Group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, etc. (these alkyl groups are linear Octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, icocenyl, And an alkenyl group such as a nicocenyl group (these alkenyl groups may be linear or branched, and the position of the double bond is arbitrary).

The acidic phosphate ester (A) used in the present invention is a compound (phosphate monoester) in which ^one of R ¹ and R ^{2 in} the general formula (1) is a hydrogen atom and the other is a hydrocarbon group. ), And compounds in which both R ¹ and R ² are hydrocarbon groups (phosphoric diesters). 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 arbitrary as long as it is contained in the lubricating oil composition at the specific ratio described above together with the component (B). From the point of being 0.001 to 10% by mass based on the total amount and excellent in low friction performance, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 1 on the basis of the total amount of the composition. It is at least 1.2 mass%, particularly preferably at least 1.2 mass%. In addition, since the obtained lubricating oil composition is superior 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 acidic phosphate is From the point of being excellent in corrosion resistance, it is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 2% by mass or less. In addition, the content of the component (A) in terms of phosphorus element is arbitrary as long as it is contained in the lubricating oil composition at the specific ratio described above together with the component (B), and depends on the molecular weight of the component (A). Although it differs, it is usually 0.0001 to 1% by mass, preferably 0.01 to 0.5% by mass, more preferably 0.05 to 0.2% by mass in terms of phosphorus element, based on the total amount of the composition. %, Particularly preferably 0.08 to 0.15% by mass.

  Component (B) in the present invention is an aliphatic amine, and is usually a monoamine, diamine, or polyamine having 1 or 2 or more alkyl or alkenyl groups having 1 to 30 carbon atoms, preferably 8 to 30 carbon atoms. Although it may be any, it is most preferable to select a monoamine having one alkyl group or alkenyl group having 8 to 30 carbon atoms. Among these alkyl groups or alkenyl groups, the carbon number of these alkyl groups and alkenyl groups is 8 from the viewpoint of excellent low-temperature storage stability when mixed with component (A) and low friction performance when mixed with cutting oil. Preferably, it is preferably 10 or more, more preferably 12 or more. Further, from the viewpoint of solubility in the lubricating base oil, the carbon number of these alkyl groups and alkenyl groups is preferably 22 or less, more preferably 16 or less, and even more preferably 14 or less. . Furthermore, the alkyl group and alkenyl group may be either linear or branched, but are preferably linear from the viewpoint of low friction performance, and more preferably linear alkyl groups. preferable.

  Specific examples of the preferable alkyl group or alkenyl group having 8 to 30 carbon atoms include octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group. Group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, etc. (these alkyl groups are linear Octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, icocenyl, Alkenyl groups such as icocenyl group, tricocenyl group, tetracocenyl group, pentacocenyl group, hexacocenyl group, heptacocenyl group, octacocenyl group, nonacosenyl group, triaconenyl group (these alkenyl groups may be linear or branched, The position of the double bond is arbitrary).

  In the lubricating oil composition of the present invention, the content of the (B) aliphatic amine is arbitrary as long as it is contained in the lubricating oil composition at the specific ratio described above together with the component (A), but is usually based on the total amount of the composition. 0.001 to 5% by mass, and in terms of excellent corrosion resistance when mixed with component (A), preferably 0.05% by mass or more, more preferably 0.1% by mass based on the total amount of the composition. % Or more, more preferably 0.15 mass% or more. Moreover, from the point which is excellent in low temperature storage stability and the low friction performance when mixing with cutting oil, content of (B) component is 0.4 mass% or less on a composition whole quantity basis, More preferably It is 0.3% by mass or less, particularly preferably 0.25% by mass or less. In addition, the content of the component (B) in terms of nitrogen element is arbitrary as long as it is contained in the lubricating oil composition at the specific ratio described above together with the component (A), and depends on the molecular weight of the component (B). Although it differs, it is usually 0.0001 to 0.5% by mass, preferably 0.001 to 0.2% by mass, and more preferably 0.005 to 0.005% in terms of nitrogen element, based on the total amount of the composition. It is 04 mass%, Most preferably, it is 0.01-0.02 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 an alkyl group or alkenyl group having 16 to 24 carbon atoms and 8 to 16 carbon atoms. In particular, a combination of oleyl acid phosphate and laurylamine is most preferable.

  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 mixed with cutting fluid, it is possible to maintain machining accuracy without significantly deteriorating the initial low-friction properties. However, even when a cutting fluid is mixed, the low friction performance of the lubricating oil composition itself of the present invention is hardly deteriorated, the friction coefficient can be kept lower, and the processing accuracy can be maintained. It is preferable to contain a polyalkylene glycol compound in that it can be maintained over a long period of time and can contribute to reduction of waste oil.

Although there is no restriction | limiting in particular as a polyalkylene glycol type compound, Specifically, the compound represented by the following general formula (2) and its derivative (s) can be illustrated, for example.
^{R 3 O- (R 4 O)} a -R 5 (2)
Here, R ³ and R ⁵ may be the same or different and are each a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group, or an arylalkyl group, and R ⁴ O represents an oxyalkylene group having 2 to 6 carbon atoms, and a is an integer of 1 to 200, preferably 2 to 100, more preferably 5 to 50. The average molecular weight of the polyalkylene glycol compound represented by the general formula (2) is preferably 500 to 5000, more preferably 1000 to 4500, and still more preferably 1500 to 4000.

  Here, the alkyl group having 1 to 6 carbon atoms may be linear, branched or cyclic, and specific examples of the alkyl group include a methyl group, an ethyl group, and an n-propyl group. Isopropyl group, various butyl groups, various pentyl groups, various hexyl groups, cyclopentyl group, cyclohexyl group, and the like. Specific examples of the aryl group, alkylaryl group or arylalkyl group having 6 to 20 carbon atoms include aryl groups such as phenyl group, naphthyl group (including all isomers); tolyl group, ethylphenyl group, propylphenyl Group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, xylyl group, ethylmethylphenyl group, diethylphenyl group , Dipropylphenyl group, dibutylphenyl group, methylnaphthyl group, ethylnaphthyl group, propylnaphthyl group, butylnaphthyl group, dimethylnaphthyl group, ethylmethylnaphthyl group, diethylnaphthyl group, dipropylnaphthyl group, dibutylnaphthyl group and these It can be exemplified benzyl group, phenylethyl group, a phenylpropyl group, and arylalkyl groups such isomers thereof; alkylaryl groups such as sex body. In these, it is more preferable that it is a C1-C6 alkyl group.

Examples of the oxyalkylene group having 2 to 6 carbon atoms include an oxyethylene group, an oxypropylene group, an oxybutylene group, an oxypentylene group, an oxyhexylene group, and a mixture thereof, and — (R ⁴ O ) a _- the homopolymers having an oxyalkylene group of one structure selected from an oxyalkylene group having 2 to 6 carbon atoms as a single structural unit, is selected from an oxyalkylene group having 2 to 6 carbon atoms Random copolymers and block copolymers having oxyalkylene groups having two or more different structures as structural units (where a represents the total degree of polymerization of the oxyalkylene groups represented by -R ⁴ O-), or a mixture of two or more polymers selected from these homopolymers and copolymers (in this case a is -R 4 ^{O-represented} in the polymer mixture That means that oxy alkylene group total average degree of polymerization is derived from each shown).

In the present invention, among the compounds represented by the general formula (2), one of R ³ and R ⁵ is a hydrogen atom and the remaining is the number of carbon atoms because the friction coefficient when mixed with water-soluble cutting oil can be kept lower. It is preferable that it is a 1-6 alkyl group, or both are hydrogen atoms, and it is especially preferable that both are hydrogen atoms.

A more preferable example of the polyalkylene glycol compound used in the present invention includes a compound represented by the following general formula (3).
^{_{R 3 O- (EO) l -}} (R 6 O) m - (EO) n -R 5 (3)
[In formula (3), ^{R 3} and ^{R 5} have the same meanings as ^{R 3} and ^{R 5} in the general formula (2), EO represents an oxyethylene group, ^{R 6} O represents an oxyalkylene group having 3 to 6 carbon atoms Wherein l, m and n may be the same or different and each represents an integer of 1 to 50]

In the general formula (3), either of R ³ and R ⁵ is a hydrogen atom and the rest is an alkyl group having 1 to 6 carbon atoms, because the friction coefficient when mixed with water-soluble cutting oil can be kept lower. It is preferable that both are hydrogen atoms, and it is particularly preferable that both are hydrogen atoms.
R ⁶ O in the general formula (3) is an oxyalkylene group having 3 to 6 carbon atoms, and examples of the oxyalkylene group of the repeating unit include an oxypropylene group (PO), an oxybutylene group, an oxypentylene group, Examples include oxyhexylene group. Among these, an oxypropylene group is preferable because it is excellent in separability from a water-soluble cutting fluid.

As the polyalkylene glycol compound in the present invention, as is clear from the fact that l, m and n representing the number of repetitions of EO, R ⁶ O and EO are each an integer of 1 to 50, an oxyalkylene chain — (R ⁶ O) _m- is preferably a block copolymer in which both ends of oxyethylene chain (EO) ₁ and (EO) _n are bonded, and any one of l, m and n is 0 Compared to the case of using a glycol derivative, it is easy to suppress an increase in the friction coefficient when water-soluble cutting oil is mixed. Further, each of l, m, and n has an average molecular weight of the polyalkylene glycol compound represented by the general formula (3) of preferably 500 to 5000, more preferably 1000 to 4500, and further preferably 1500 to 4000. Such a value is desirable. Further, the ratio (l + n) / (l + m + n) of the sum of l and n to the sum of l, m and n is preferably 0.05 to 0.8, and is 0.08 to 0.7. More preferably, it is more preferably 0.09 to 0.5. When (l + n) / (l + m + n) is within the above range, even when mixed with a water-soluble cutting fluid, low friction performance tends to be easily maintained over a long period of time.

When m is 2 or more, the m R ⁶ Os may be the same or different. When the oxyalkylene chain (R ⁶ O) _m is composed of two or more types of R ⁶ O, the oxyalkylene chain may be a block copolymer chain or a random copolymer chain.

  In this invention, the said polyalkylene glycol type compound may be used individually by 1 type, and may be used in combination of 2 or more type. Further, the content is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.1% by mass, and particularly preferably 0.005 to 0.05% by mass based on the total amount of the composition.

  The lubricating oil composition of the present invention comprises the lubricating base oil containing the component (A) and the component (B), or the lubricating base oil and the component (A) and (B ) When the composition is composed of components, or by further containing a polyalkylene glycol compound, it is excellent in low friction and low-temperature storage stability and cutting fluid is mixed without using other additives. However, it is possible to maintain the processing accuracy without significantly deteriorating the initial low friction property, 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.

  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 sulfur-based extreme pressures such as sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiadiazole compounds, alkylthiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and dialkylthiodipropionate compounds. Agents, monohydric alcohols or polyhydric alcohols, monobasic acids or polybasic acids, esters of the alcohol and the acids, oily agents such as amine compounds such as monoamines, polyamines, alkanolamines, di-tert-butyl-p- Antioxidants such as cresol, phenolic compounds such as bisphenol A, amine-based compounds such as phenyl-α-naphthylamine and N, N′-di (2-naphthyl) -p-phenylenediamine; benzotriazole and alkylthiadiazole Metal deactivators; defoaming agents such as silicone oils and fluorosilicone oils; phosphorus-based additives other than acidic phosphates (ordinary phosphates, phosphites, amine salts of acidic (sub) phosphates Oily agents such as carboxylic acids; rust inhibitors such as alkenyl succinic acid and sorbitan monooleate; pour point depressants such as polymethacrylates; polymethacrylates, polybutenes, polyalkylstyrenes, olefin copolymers, styrene-diene copolymers, And viscosity index improvers such as styrene-maleic anhydride copolymers.

  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 to 4, Comparative Examples 1 to 5]
In Examples 1 to 4 and Comparative Examples 1 to 5, lubricating oil compositions having the compositions shown in Table 1 were prepared using the base oils and additives shown in Table 1, respectively.
Next, the following tests were performed on the lubricating oil compositions of Examples 1 to 4 and Comparative Examples 1 to 5.

(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, and after adjusting the surface pressure between the table 1 and the bed 6 to 200 kPa by selecting the table weight 9, the feed rate is 1.2 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. Table 1 shows the friction coefficient of each lubricating oil composition.

(Frictional property evaluation test when cutting oil is mixed)
A 1000 ml beaker containing 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 K 2241 “Cutting fluid” equivalent to W1 type 1 and a dilution ratio of 10) Collected. Gently stirred with a magnetic rotor for 1 minute at room temperature in a beaker. Table 1 shows the results of the friction property evaluation test that was allowed to stand for 1 hour after stirring and used as a measurement sample. If the friction coefficient at the time of cutting oil mixing is 0.110 or less, it is an acceptable range, and if it is 0.09 or less, it is judged as extremely excellent.

(Low temperature storage stability test)
A cycle in which 500 ml of each lubricating oil composition is collected in a glass beaker and placed in a temperature-adjustable container, and mode A (0 ° C., 12 hours) and mode B (20 ° C., 12 hours) are alternately repeated. Drove. The appearance of each lubricating oil composition after 30 days was visually observed, and the low-temperature storage stability was evaluated by the presence or absence of precipitates or precipitates. The obtained results are shown in Table 1. The evaluation criteria are as follows.
○: No precipitate or precipitate ×: Obviously there is a precipitate or precipitate

(Corrosion resistance test)
200 ml of each lubricating oil composition was sampled in a glass beaker, and a 7 cm square SPC material (thickness 0.2 mm, 80th dull finish) degreased with methanol was immersed in the 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.
○: No discoloration △: Slightly discolored ×: Clearly discolored

  As is clear from the results shown in Table 1, the lubricating oil compositions of Examples 1 to 4 have a low friction performance (low coefficient of friction) compared to the compositions of Comparative Examples 1 to 5, and the cutting oil It can be seen that low friction performance can be maintained even when mixed, excellent low-temperature storage stability, and satisfactory corrosion resistance.

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

Claims (2)

In the lubricating base oil, (A) an acidic phosphate ester represented by the following general formula (1) and (B) an aliphatic amine, and / or (A) an acidic phosphoric acid represented by the following general formula (1) The reaction product of the ester and (B) aliphatic amine has a mass ratio (P / N) of 4 between the phosphorus content (P) due to the component (A) and the nitrogen content (N) due to the component (B). The acidic phosphate ester is a mixture of a phosphoric acid monoester and a phosphoric acid diester, and the mixing ratio of the former and the latter is 10/90 to 90 / in molar ratio. The lubricating oil composition according to claim 10, wherein the (B) aliphatic amine is a primary amine and / or a secondary amine, and further contains (C) a polyalkylene glycol compound .

[Wherein, R ¹ and R ² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 8 to 22 carbon atoms, and at least one of R ¹ and R ² is a hydrocarbon group. ] The lubricating oil composition according to claim 1, wherein the lubricating oil composition is used in a machine tool.

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