JP7213694B2 - Sulfur-based compound, lubricating oil additive containing said sulfur-based compound, and lubricating oil composition containing said sulfur-based compound - Google Patents

Description

The present invention relates to a sulfur-based compound, a lubricating oil additive containing the sulfur-based compound, and a lubricating oil composition containing the sulfur-based compound.

Conventionally, sulfur compounds such as sulfurized esters and sulfurized olefins (also called polysulfides) have been used as performance additives (lubricating oil additives) to improve the performance of lubricating oils in the field of lubricating oils (for example, patent References 1, 2).

JP 2015-74694 A JP-A-2015-89900

An object of the present invention is to provide a sulfur-based compound useful as a lubricating oil additive, a lubricating oil additive containing the sulfur-based compound, and a lubricating oil composition containing the sulfur-based compound.

One aspect of the present invention is a compound represented by the following formula (1).

［式（１）中、Ｒ^１及びＲ^１０はそれぞれ独立に炭素数３～２４のアルキル基を表し、Ｒ^２及びＲ^３はそれぞれ独立に水素原子又はメチル基を表し、Ｒ^２及びＲ^３のうち少なくとも一方が水素原子を表し、Ｒ^８及びＲ^９はそれぞれ独立に水素原子又はメチル基を表し、Ｒ^８及びＲ^９のうち少なくとも一方が水素原子を表し、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^７はそれぞれ独立に水素原子又はメチル基を表し、ｘは１～８の整数を表し、ｍ及びｎはそれぞれ独立に０又は１の整数を表す。ただし、Ｒ^４及びＲ^５のうち少なくとも一方がメチル基を表す場合、ｍは０の整数を表し、Ｒ^４及びＲ^５がともに水素原子を表す場合、ｍは１の整数を表し、Ｒ^６及びＲ^７のうち少なくとも一方がメチル基を表す場合、ｎは０の整数を表し、Ｒ^６及びＲ^７がともに水素原子を表す場合、ｎは１の整数を表す。］

[In formula (1), R ¹ and R ¹⁰ each independently represent an alkyl group having ³ to 24 carbon atoms; R ² and R ^{3 each} independently represent a hydrogen atom or a methyl group; at least one of which represents a hydrogen atom, R ⁸ and R ⁹ each independently represents a hydrogen atom or a methyl group, at least one of R ⁸ and R ⁹ represents a hydrogen atom, R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represents a hydrogen atom or a methyl group, x represents an integer of 1 to 8, and m and n each independently represent an integer of 0 or 1; However, when at least one of R ⁴ and R ⁵ represents a methyl group, m represents an integer of 0, and when both R ⁴ and R ⁵ represent a hydrogen atom, m represents an integer of 1, and R ⁶ and When at least one of R ⁷ represents a methyl group, n represents an integer of 0, and when both R ⁶ and R ⁷ represent a hydrogen atom, n represents an integer of 1. ]

The present invention, in one aspect, is a lubricating oil additive containing the above compound.

One aspect of the present invention is a lubricating oil composition containing a lubricating base oil and the above compound.

The lubricating oil composition may further contain a metallic detergent.

The lubricating oil composition is preferably used as a metal working oil, and more preferably used as a plastic working oil or a cutting oil.

According to the present invention, it is possible to provide a sulfur-based compound useful as a lubricating oil additive, a lubricating oil additive containing the sulfur-based compound, and a lubricating oil composition containing the sulfur-based compound.

13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. 13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. 13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. 13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. 13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. 13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. 13 is a ¹³ C-NMR chart of a sulfur compound mixture obtained in an example. It is a schematic cross-sectional view showing the configuration of a burring tester used in Examples. It is a schematic cross-sectional view showing the configuration of a draw bead tester used in Examples.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

(Compound represented by formula (1))
The compound (hereinafter also referred to as "sulfur-based compound") according to the present embodiment is represented by the following formula (1).

In formula (1), R ¹ and R ¹⁰ each independently represent an alkyl group having 3 to 24 carbon atoms. The alkyl groups represented by R ¹ and R ¹⁰ preferably have 8 to 16 carbon atoms. The alkyl groups represented by R ¹ and R ¹⁰ may be linear or branched. Examples of alkyl groups represented by R ¹ and R ¹⁰ include n-butyl, i-butyl, t-butyl, 2-ethylhexyl, lauryl, stearyl and isostearyl groups. R ¹ and R ¹⁰ may be the same or different.

^R2 and R3 ^each independently represent a hydrogen atom or a methyl group. However, at least one of R ² and R ³ represents a hydrogen atom.

^R8 and ^R9 each independently represent a hydrogen atom or a methyl group. However, at least one of ^R8 and ^R9 represents a hydrogen atom.

x represents an integer of 1 to 8; The integer represented by x may be 1 or more, 2 or more, or 3 or more, and may be 8 or less, 7 or less, or 6 or less.

R ⁴ , R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom or a methyl group; m and n each independently represent an integer of 0 or 1; However, the sulfur compound according to the present embodiment satisfies the following conditions for R ⁴ , R ⁵ , R ⁶ , R ⁷ , m and n.
m represents an integer of 0 when at least one of R ⁴ and R ⁵ represents a methyl group.
m represents an integer of 1 when both R ⁴ and R ⁵ represent a hydrogen atom;
n represents an integer of 0 when at least one of R ⁶ and R ⁷ represents a methyl group.
n represents an integer of 1 when both R ⁶ and R ⁷ represent a hydrogen atom;

The sulfur-based compound according to this embodiment can be produced, for example, as follows. First, in an autoclave, a compound represented by the following formula (A-1) or the following formula (A-2) (acrylic acid or methacrylic acid ester, hereinafter also referred to as "(A) component"), sulfur and a catalyst (for example diammonium sulfide, dioctylamine). The compounding ratio of sulfur to component (A) (molar ratio; sulfur/component (A)) is, for example, 5/100 to 40/100 by weight. The compounding ratio of the catalyst to the component (A) (molar ratio: catalyst/component (A)) is, for example, 1/1000 to 30/1000. Hydrogen sulfide gas is introduced into the autoclave until it reaches 0.8 to 1.5 MPa, for example. Subsequently, for example, stirring is performed at room temperature (25° C.) for 1 to 10 hours. After the reaction sample after stirring is heated to, for example, 80° C. to melt, the reaction sample is filtered by suction filtration, and the catalyst is removed by liquid separation to obtain the target product (sulfur compound). It is possible.

In the formula, R ¹¹ has the same definition as R ¹ and R ¹⁰ in formula (1).

Examples of the compound represented by formula (A-1) include n-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, and isostearyl acrylate. Examples of the compound represented by formula (A-2) include n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, and the like. .

The sulfur-based compound described above can be used as an additive for lubricating oil as described later, and can improve the metal workability of the lubricating oil composition. In addition, the sulfur-based compound is also useful as an antioxidant because it can improve the antioxidant performance of the lubricating oil when added to the lubricating oil.

(lubricant additive)
The lubricating oil additive according to this embodiment contains a sulfur compound. The lubricating oil additive may consist solely of a sulfur-based compound, or may be a mixture of a sulfur-based compound and other additives. Other additives include anti-wear agents, metal deactivators, metallic detergents, ashless dispersants, viscosity index improvers, defoamers, pour point depressants, corrosion inhibitors, rust inhibitors, demulsifiers. etc. When the lubricating oil additive is a mixture of a sulfur-based compound and other additives, the blending amount of the sulfur-based compound and other additives is appropriately selected according to the use and purpose of the lubricating oil additive. good. The lubricating oil additive may further contain a diluent for dissolving the additive. Diluents are, for example, mineral oil diluents, synthetic oil diluents and mixtures thereof. When the lubricating oil additive is a mixture of a sulfur-based compound and other additives, the content of the sulfur-based compound may be, for example, 20 to 80% by mass based on the total amount of the lubricating oil additive.

(Lubricating oil composition)
The lubricating oil composition according to the present embodiment contains a lubricating base oil and a sulfur compound. Lubricating base oils are, for example, mineral oils, synthetic oils, or mixtures of both.

As the mineral oil, the lubricating oil fraction obtained by atmospheric distillation and vacuum distillation of the raw material is subjected to solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay Mineral oils such as paraffinic oils and naphthenic oils, normal paraffins, isoparaffins, etc., refined by refining treatments such as treatment alone or in combination of two or more, may be mentioned. These mineral oils may be used singly or in combination of two or more at any ratio.

Preferred mineral oils include the following base oils.
(1) Distillates obtained by atmospheric distillation of paraffin-based and/or mixed-base crude oils.
(2) Vacuum distillation distillates (WVGO) of atmospheric distillation residues of paraffinic base and/or mixed base crudes.
(3) Waxes obtained by the lubricating oil dewaxing process and/or Fischer-Tropsch waxes produced by the GTL process or the like.
(4) A mild hydrocracked oil (MHC) of one or more mixed oils selected from (1) to (3) above.
(5) Mixed oil of two or more oils selected from (1) to (4) above.
(6) The deasphalted oil (DAO) of (1), (2), (3), (4) or (5) above.
(7) The mild hydrocracked oil (MHC) of (6) above.
(8) A mixed oil of two or more oils selected from the above (1) to (7) is used as a raw material oil, and this raw material oil and / or a lubricating oil fraction recovered from this raw material oil is usually Lubricating oil obtained by refining by the refining method of and recovering the lubricating oil fraction.

Here, as the ordinary refining method, any refining method used in the production of base oil can be arbitrarily adopted. Usual purification methods include, for example, the following purification methods.
(a) hydrorefining such as hydrocracking and hydrofinishing;
(b) solvent refining, such as furfural solvent extraction;
(c) Dewaxing such as solvent dewaxing and contact dewaxing.
(d) Clay refining using acid clay, activated clay, or the like.
(e) chemical (acid or alkali) refining such as sulfuric acid cleaning and caustic soda cleaning;
These purification methods can be employed singly or in any combination and in any order of two or more.

Synthetic oils include, for example, esters, ethers and hydrocarbon oils. These synthetic oils may be used singly or in combination of two or more at any ratio.

Esters can be, for example, esters of fatty acids (monobasic acids) and alcohols, or polybasic acids and alcohols.

Fatty acids may be saturated fatty acids or unsaturated fatty acids. Fatty acids may be, for example, fatty acids having 2 to 24 carbon atoms. Fatty acids may be linear or branched. Examples of polybasic acids include dibasic acids and tribasic acids. A polybasic acid may or may not have an unsaturated bond. The number of carbon atoms in the polybasic acid may be, for example, 2-16. The dibasic acid may be linear or branched.

The alcohol may be a monohydric alcohol or a polyhydric alcohol. The monohydric alcohol may have, for example, 1-24, 1-12, or 1-8 carbon atoms. The monohydric alcohol may be linear or branched. The number of hydroxyl groups possessed by the polyhydric alcohol (polyol) may be, for example, 2-10, or 2-6.

Ethers include, for example, polyoxyalkylene glycol, dialkyldiphenyl ether, polyphenyl ether and the like.

Hydrocarbon oils include, for example, poly-α-olefins or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes and the like.

The kinematic viscosity at 40° C. of the lubricating base oil may be 1 mm ² /s or higher, 3 mm ² /s or higher, or 5 mm ² /s or higher. The kinematic viscosity at 40° C. of the lubricating base oil may be 500 mm ² /s or less, 300 mm ² /s or less, 200 mm ² /s or less, or 50 mm ² /s or less.

When the lubricating oil composition is used as a plastic working oil, the kinematic viscosity of the lubricating base oil at 40° C. is preferably 15 mm ² /s or more, more preferably 50 mm ² /s or more, and still more preferably 100 mm ² /s or more. be. When the lubricating oil composition is used as a plastic working oil, the kinematic viscosity of the lubricating base oil at 40° C. is preferably 300 mm ² /s or less, more preferably 250 mm ² /s or less, and still more preferably 200 mm ² /s or less. be.

When the lubricating oil composition is used as a cutting oil, the kinematic viscosity of the lubricating base oil at 40° C. is preferably 5 mm ² /s or more, more preferably 8 mm ² /s or more, and still more preferably 10 mm ² /s or more. be. When the lubricating oil composition is used as a cutting oil, the kinematic viscosity at 40° C. of the lubricating base oil is preferably 40 mm ² /s or less, more preferably 30 mm ² /s or less, still more preferably 25 mm ² /s or less. be.

The kinematic viscosity at 100° C. of the lubricating base oil may be 0.5 mm ² /s or greater, 1.0 mm ² /s or greater, or 1.5 mm ² /s or greater. The 100° C. kinematic viscosity of the lubricating base oil may be 50 mm ² /s or less, 40 mm ² /s or less, or 30 mm ² /s or less.

When the lubricating oil composition is used as a plastic working oil, the kinematic viscosity of the lubricating base oil at 100° C. is preferably 3 mm ² /s or more, more preferably 7 mm ² /s or more, and still more preferably 10 mm ² /s or more. be. When the lubricating oil composition is used as a plastic working oil, the kinematic viscosity of the lubricating base oil at 100° C. is preferably 20 mm ² /s or less, more preferably 18 mm ² /s or less, still more preferably 15 mm ² /s or less. be.

When the lubricating oil composition is used as a cutting oil, the kinematic viscosity at 100° C. of the lubricating base oil is preferably 1.5 mm ² /s or more, more preferably 2.5 mm ² /s or more, and still more preferably 3.5 mm 2 /s or more. 5 mm ² /s or more. When the lubricating oil composition is used as a cutting oil, the kinematic viscosity of the lubricating base oil at 100° C. is preferably 7 mm ² /s or less, more preferably 5 mm ² /s or less, and still more preferably 4 mm ² /s or less. be.

Kinematic viscosity in the present invention means kinematic viscosity measured according to JIS K2283:2000.

The content of the lubricating base oil may be, for example, 50% by mass or more, 70% by mass or more, or 90% by mass or more based on the total amount of the lubricating oil composition.

Preferred aspects of the sulfur-based compound are as described above. The content of the sulfur compound is 0.1% by mass or more, 0.5% by mass or more, 0.7% by mass or more, 0.9% by mass or more, or 5% by mass or more based on the total amount of the lubricating oil composition. and may be 50% by mass or less, 40% by mass or less, or 30% by mass or less. When the lubricating oil composition contains two or more sulfur-based compounds, the above content is the total content of the two or more sulfur-based compounds.

The content of elemental sulfur in the lubricating oil composition may be 0.1% by mass or more, 0.2% by mass or more, or 1% by mass or more, and 30% by mass or less, based on the total amount of the lubricating oil composition. , 20% by mass or less, or 10% by mass or less.

The lubricating oil composition according to the present embodiment may further contain additives other than sulfur compounds. Other additives include anti-wear agents, metal deactivators, metallic detergents, ashless dispersants, viscosity index improvers, defoamers, pour point depressants, corrosion inhibitors, rust inhibitors, demulsifiers. etc.

The lubricating oil composition preferably further contains, among other additives, a metallic detergent. The metallic detergent may be, for example, an overbased organic acid metal salt. An overbased metal salt of an organic acid is a compound obtained by overbasing a metal salt of an organic acid with a carbonate, a borate, or the like. Organic acid metal salts include alkali metal or alkaline earth metal sulfonates, phenates or salicylates.

Carbonate overbased organic acid metal salts overbased with carbonates are, for example, neutral (normal) sulfonates, phenates or salicylates in the presence of carbon dioxide, alkali metal bases or alkaline earth metals. obtained by reacting with a base of A borate overbased organic acid metal salt overbased with a borate is obtained, for example, by reacting an organic acid metal salt, calcium hydroxide or calcium oxide, and boric acid or boric anhydride. be done.

Alkali metals may be sodium, potassium, and the like. The alkaline earth metal may be magnesium, calcium, barium, etc., preferably calcium. The overbased organic acid metal salt is preferably an overbased calcium sulfonate.

The total base number of the overbased organic acid metal salt may be 50 mg/KOH or more, 100 mgKOH/g or more, or 150 mgKOH/g or more, and may be 500 mgKOH/g or less, 470 mgKOH/g or less, or 420 mgKOH/g or less. you can The total base number in this specification is 7. of JIS K 2501 "Petroleum products and lubricating oils-neutralization number test method". Means the total base number (mgKOH/g) by the perchloric acid method measured according to.

When the lubricating oil composition contains an overbased organic acid metal salt, the content of the overbased organic acid metal salt is, based on the total amount of the lubricating oil composition, 3% by mass or more, 5% by mass or more, and 10% by mass. or more, or 20% by mass or more, and may be 60% by mass or less, 57% by mass or less, 53% by mass or less, or 50% by mass or less.

The kinematic viscosity at 40° C. of the lubricating oil composition may be 1 mm ² /s or higher, 3 mm ² /s or higher, or 5 mm ² /s or higher. The kinematic viscosity at 40° C. of the lubricating oil composition may be 500 mm ² /s or less, 300 mm ² /s or less, 200 mm ² /s or less, or 50 mm ² /s or less.

When the lubricating oil composition is used as a plastic working oil, the kinematic viscosity of the lubricating oil composition at 40° C. is preferably 15 mm ² /s or more, more preferably 50 mm ² /s or more, and still more preferably 100 mm ² /s or more. be. When the lubricating oil composition is used as a plastic working oil, the kinematic viscosity of the lubricating oil composition at 40° C. is preferably 300 mm ² /s or less, more preferably 250 mm ² /s or less, and still more preferably 200 mm ² /s or less. be.

When the lubricating oil composition is used as a cutting oil, the kinematic viscosity of the lubricating oil composition at 40° C. is preferably 5 mm ² /s or more, more preferably 8 mm ² /s or more, and still more preferably 10 mm ² /s or more. be. When the lubricating oil composition is used as a cutting oil, the kinematic viscosity of the lubricating oil composition at 40° C. is preferably 40 mm ² /s or less, more preferably 30 mm ² /s or less, and still more preferably 25 mm ² /s or less. be.

The lubricating oil composition according to the present embodiment can be widely used in the lubricating oil field. The lubricating oil composition is useful as metal working oil, lubricating oil for drive systems such as automatic transmissions or manual transmissions, hydraulic oil, turbine oil, compressor oil, and the like.

A lubricating oil composition is suitably used as a metal working oil. The metal working oil is, for example, a plastic working oil, a cutting oil, a grinding oil, or the like. Examples of plastic working include drawing, ironing, drawing, pressing, rolling, forging, and rolling. The lubricating oil composition is preferably used for plastic working and cutting. The workpiece may be a difficult-to-work material such as a steel plate, a stainless steel plate, a surface-treated steel plate, an aluminum alloy plate, or a titanium alloy.

EXAMPLES The present invention will be described in more detail based on examples below, but the present invention is not limited to the examples.

[Synthesis of sulfur compound]
An autoclave (300 mL) was charged with 99.3 g of raw lauryl methacrylate, 22.6 g of sulfur and 1.2 g of dioctylamine as a catalyst. Hydrogen sulfide gas was introduced into the autoclave up to 1 MPa, the leak was repeated three times, and finally hydrogen sulfide was introduced up to 1.0 MPa. Heat at 120° C. for 3 hours with stirring. At that time, hydrogen sulfide was appropriately added so as to maintain 1 MPa. After that, the temperature was raised to 155° C., and the mixture was stirred for 6 hours while being heated. No hydrogen sulfide was added at this time. Finally, the reaction sample was filtered by suction filtration to obtain 107 g of a mixture containing the desired product.

The product obtained by the raw material compound and synthesis method, and NMR analysis is a mixture of sulfur compounds represented by the following formulas (1a), (1b) and (1c), A mixture of sulfur compounds in which m represents an integer of 1 to 5, n in formula (1b) represents an integer of 1 to 4, and l in formula (1c) represents an integer of 3 to 5 (hereinafter referred to as It was confirmed that it was simply referred to as "a mixture of sulfur compounds"). ¹³ C-NMR charts of the obtained mixture are shown in FIGS. 1 to 6. FIG.

In FIG. 1, the mixture of sulfur compounds obtained above was subjected to column treatment using silica gel as the stationary phase and hexane as the eluent, and then eluted with toluene. It is an analyzed ¹³ C-NMR chart. In FIG. 1, the peaks of m = 1 to m = 5 and the peaks of l = 3 to l = 5 are the carbon atoms of * in the compounds where m is 1 to 5 in formula (1a), and the formula (1c) shows the signal due to the * carbon atoms of compounds where l is 3-5.

FIG. 2 shows that the mixture of sulfur compounds obtained above was subjected to column treatment using silica gel as the stationary phase, hexane as the eluent, and then toluene, and then a mixed solvent of toluene and acetone (mixing ratio: toluene : acetone = 9: ¹ ), and the mixed solvent elution fraction was analyzed.

Further, the mixture of sulfur compounds obtained above was mixed with silica gel as a stationary phase, hexane as an eluent, a mixed solvent of hexane and toluene (mixture ratio: hexane:toluene = 2:8), toluene, a mixture of toluene and acetone. Column treatment was performed using a solvent (mixing ratio; toluene:acetone=8:2) and methanol in this order. Each eluted fraction at this time is shown in FIGS. 3 to 7. FIG. FIG. 3 is a ¹³ C-NMR chart obtained by analyzing the methanol-eluted fraction. FIG. 4 is a ¹³ C-NMR chart obtained by analyzing fractions eluted from a mixed solvent of toluene and acetone (mixture ratio: toluene:acetone=8:2). FIG. 5 is a ¹³ C-NMR chart analyzing the toluene elution fraction. FIG. 6 is a ¹³ C-NMR chart obtained by analyzing fractions eluted from a mixed solvent of hexane and toluene (mixing ratio: hexane:toluene=2:8). FIG. 7 is an enlarged view of part of the area of FIG.

In FIGS. 2 to 7, peaks such as A1 and B2 indicate signals due to carbon atoms such as A1 and B2 in compounds represented by the following formulas (A) to (I), respectively. For example, in FIG. 3, the C1 peak indicates a signal due to the C1 carbon atom of the compound represented by formula (C). In addition, the peaks of l=3 to l=5 of J in FIG. 7 indicate signals due to the * carbon atoms of the compounds of l=3 to l=5 in the following formula (J).

[Preparation of lubricating oil composition]
Using the base oils and additives shown below, lubricating oil compositions having the compositions shown in Tables 1 to 3 (based on the total amount of the lubricating oil composition, mass %) were prepared.

(base oil)
A1-1: Group I base oil [solvent refined mineral oil, kinematic viscosity at 40°C: 76.13 mm ² /s, kinematic viscosity at 100°C: 9.793 mm ² /s, viscosity index: 108]
A1-2: Group I base oil [solvent refined mineral oil, kinematic viscosity at 40°C: 6.7 mm ² /s, kinematic viscosity at 100°C: 2.0 mm ² /s, viscosity index: 97]
A1-3: Group I base oil [solvent refined mineral oil, kinematic viscosity at 40°C: 27.78 mm ² /s, kinematic viscosity at 100°C: 4.93 mm ² /s, viscosity index: 100]
A1-4: Group I base oil [solvent refined mineral oil, kinematic viscosity at 40°C: 74.43 mm ² /s, kinematic viscosity at 100°C: 9.227 mm ² /s, viscosity index: 99]
A1-5: Group I base oil [solvent refined mineral oil, kinematic viscosity at 40°C: 483.3 mm ² /s, kinematic viscosity at 100°C: 32.07 mm ² /s, viscosity index: 98]
A1-6: Group I base oil [solvent refined mineral oil, kinematic viscosity at 40°C: 9.334 mm ² /s, kinematic viscosity at 100°C: 2.531 mm ² /s, viscosity index: 98]
A2: Group II base oil [hydrocracked mineral oil, kinematic viscosity at 40° C.: 80.63 mm ² /s, kinematic viscosity at 100° C.: 9.890 mm ² /s, viscosity index: 102]
A3: Group III base oil [hydrocracked mineral oil, kinematic viscosity at 40° C.: 72.33 mm ² /s, kinematic viscosity at 100° C.: 9.993 mm ² /s, viscosity index: 120]
A4-1: Group IV base oil [poly-α-olefin, kinematic viscosity at 40°C: 16.95 mm ² /s, kinematic viscosity at 100°C: 3.862 mm ² /s, viscosity index: 122]
A4-2: Group IV base oil [poly-α-olefin, kinematic viscosity at 40°C: 401.9 mm ² /s, kinematic viscosity at 100°C: 40.07 mm ² /s, viscosity index: 149]

(Additive)
a1: mixture of sulfur compounds (sulfur content: 20.2% by mass)
b1: A compound represented by the following formula (b1), wherein y is an integer of 1 to 7 (sulfurized methyl oleate, mixture, sulfur content: 18.4% by mass)

ｂ２：下記式（ｂ２）で表される化合物であって、ｚが２～７の整数である化合物（混合物、硫黄含有量：２６．４質量％）

b2: A compound represented by the following formula (b2), wherein z is an integer of 2 to 7 (mixture, sulfur content: 26.4% by mass)

ｂ３：下記式（ｂ３）で表される化合物であって、ｗが３～８の整数である化合物（混合物、硫黄含有量：３７．４質量％）

b3: A compound represented by the following formula (b3), wherein w is an integer of 3 to 8 (mixture, sulfur content: 37.4% by mass)

c: calcium sulfonate (calcium content: 15% by mass, total base number: 400 mgKOH/g)

[Evaluation of metal workability (plastic workability)]
In order to evaluate the metal workability (plastic workability) of each lubricating oil composition of each example and comparative example shown in Tables 1 to 3, a burring test, which is an evaluation method simulating ironing shown below, was performed. rice field. The results are shown in Tables 1-3.

FIG. 8 is a schematic cross-sectional view showing the configuration of the burring tester used in this test. The burring tester shown in FIG. 2 and a punch 5 provided above the die 2.

In the test, first, using a waste cloth impregnated with the lubricating oil composition, 1 to 2 g / m ² on both sides of the test piece 6 (material SUS304 material, outer diameter 80 mm, inner diameter 4.5 mm, thickness 2 mm) The lubricating oil composition was applied so as to be Next, a test piece 6 and a steel ball 7 (material SUJ2, diameter 15 mm) are placed on the die 2, and while holding them with a wrinkle-retaining member 4, the steel ball 7 is pressed from above by a punch 5, and a die cushion is applied. 3 was lifted and the test piece 6 was squeezed. At this time, the test temperature was 100° C., and the processing speed was 10 mm/s. Machinability was determined by visually observing the degree of damage to the steel ball after the test. Also, when the workability was the lowest, the steel ball did not penetrate the test piece and the test piece broke. Judgment criteria are described below.
S: Almost no scratches on the steel ball.
A: The steel ball is slightly damaged.
B: There is slight adhesion or seizure on the steel ball.
C: There is a large amount of adhesion or seizure on the steel ball.
D: The test piece breaks.

A draw bead test, which is an evaluation method simulating drawing, was performed on each of the lubricating oil compositions of Examples and Comparative Examples shown in Table 4 to evaluate metal workability (plastic workability). Table 4 shows the results.

FIG. 9 is a schematic cross-sectional view showing the configuration of the draw bead tester used in this test. The draw bead tester shown in FIG. 9 comprises a block 11 (shoulder R=4.75 mm) provided with projections corresponding to beads and a block 12 (shoulder R=2 mm) opposed thereto.

In the test, first, using a waste cloth impregnated with a lubricating oil composition, 1 to 2 g / The lubricating oil composition was applied so as to be m ² . Next, the upper end of the test piece 13 was fixed with a chuck of a tensile tester, and the lower end was sandwiched between blocks 11 and 12 and held down by hydraulic pressure with a load of 1 kN. The test piece 13 was pulled upward by 100 mm at a speed of 1.66 mm/s, and the pull-out force was measured by the load cell of the tensile tester. SKD11 (nitriding treatment, 60HRC) was used for blocks 11 and 12, which were previously polished with abrasive paper (No. 3000) and degreased with normal hexane before the test. The superiority or inferiority of the lubricating oil composition is determined using the pull-out load when the pull-out distance is 50 mm, and the lower the pull-out load, the better the lubricating performance.

[Evaluation of metal workability (cutting workability)]
A tapping test was conducted under the following conditions by alternately using each of the lubricating oil compositions of Examples and Comparative Examples shown in Table 5 and di-2-ethylhexyl adipate as a comparative standard oil. When the lubricating base oil was supplied to the machined part, it was sprayed directly onto the machined part at a rate of 6 L/hour.
Tapping conditions:
Work material: JIS S25C (carbon mesh)
Tool diameter: 8mm
Tap pitch: 1.25mm
Tap rake angle: 1.5 degrees Tap bite angle: 10 degrees Tap hole diameter: 6.8 mm
Rotation speed: 360rpm
Standard oil: di-2-ethylhexyl adipate

The tapping energy in the above test was measured, and the tapping energy efficiency (%) was calculated using the following formula.
Tapping energy efficiency (%) = (Tapping energy when using comparative standard oil) / (Tapping energy when using lubricating oil composition) x 100

Table 5 shows the results. In the table, the higher the tapping energy efficiency, the better the metal workability (cutting workability).

DESCRIPTION OF SYMBOLS 1... Support body, 2... Die, 3... Die cushion, 4... Wrinkle control member, 5... Punch, 6... Test piece, 7... Steel ball, 11, 12... Block, 13... Test piece.

Claims (2)

A lubricating oil composition containing a lubricating base oil, a compound represented by the following formula (1), and a metallic detergent and used as a metal working oil.

[In formula (1), R ¹ and R ¹⁰ each independently represent an alkyl group having ⁸ to 16 carbon atoms; R ² and R ^{3 each} independently represent a hydrogen atom or a methyl group; at least one of which represents a hydrogen atom, R ⁸ and R ⁹ each independently represents a hydrogen atom or a methyl group, at least one of R ⁸ and R ⁹ represents a hydrogen atom, R ⁴ , R ⁵ , R ⁶ and Each R ⁷ independently represents a hydrogen atom or a methyl group, x represents an integer of 3 to 8, and m and n each represent an integer of 0 or 1. However, when at least one of R ⁴ and R ⁵ represents a methyl group, m represents an integer of 0, and when both R ⁴ and R ⁵ represent a hydrogen atom, m represents an integer of 1, and R ⁶ and When at least one of R ⁷ represents a methyl group, n represents an integer of 0, and when both R ⁶ and R ⁷ represent a hydrogen atom, n represents an integer of 1. At least one of m and n is 1, and when m is 1, at least one of R ² and R ³ represents a methyl group, and when n is 1, one of R ⁸ and R ⁹ represents a methyl group. ] 2. The lubricating oil composition according to claim 1, which is used as a plastic working oil or cutting oil.

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