JP2017160293A - Lubricant composition for buffers, and method of producing lubricant composition for buffers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricant composition for buffers that has a low frictional coefficient between rubber material and metal, and shows excellent friction reduction effect, and a method of producing the lubricant composition for buffers.SOLUTION: A lubricant composition for buffers comprises (A) a base oil, (B) an aliphatic acid represented by formula (b), (C) at least one acidic phosphoester compound selected from a compound represented by formula (c) and an amine salt of the compound (R is a C12-30 alkyl group or a C12-30 alkenyl group) [m is 1 or 2; R is a C10-40 alkyl group or a C10-40 alkenyl group; If m is 2, Rs are independent of each other].SELECTED DRAWING: None

Description

  The present invention relates to a lubricating oil composition for shock absorbers and a method for producing the lubricating oil composition for shock absorbers.

Suspensions with shock absorbers are incorporated in motorcycles and automobiles to reduce vibrations caused by road surface irregularities and vibrations that occur during sudden acceleration and braking. ing. The structure of the shock absorber is basically a cylindrical structure using the flow resistance of oil, and specifically, a hydraulic piston having a small hole is used.
The friction (friction) of the shock absorber is particularly likely to occur between an oil seal made of a rubber material and a rod plated with metal such as chromium. The generation of friction in the shock absorber is a factor that deteriorates the riding comfort performance. Therefore, in order to move smoothly when the shock absorber rod expands and contracts, it is required to reduce the friction between the rubber material and the metal. .

The lubricating oil composition used for reducing the friction between the rubber material and the metal is required to have a higher friction reducing effect.
For example, Patent Document 1 discloses that a lubricating oil base oil contains a basic compound having an alkyl group or alkenyl group and a basic polar group, and a nitrogen-containing carboxylic acid having an alkyl group or alkenyl group in a specific amount. A hydraulic fluid composition for a shock absorber is disclosed.

JP 2005-255715 A

  However, the hydraulic fluid composition for a shock absorber described in Patent Document 1 is still insufficient in the effect of reducing the friction between the rubber material and the metal, and further improvement is required.

  An object of the present invention is to provide a lubricating oil composition having a small friction coefficient between a rubber material and a metal and having an excellent friction reducing effect, and a method for producing the lubricating oil composition.

The present inventor has found that a lubricating oil composition containing a fatty acid having an alkyl group or an alkenyl group having a specific carbon number together with a base oil can solve the above problems, and has completed the present invention.
That is, the present invention provides the following [1] to [2].

[1] Base oil (A), fatty acid (B) represented by general formula (b) below, compound (C1) represented by general formula (c) below, and amine salt (C2) of compound (C1) And at least one acidic phosphate ester compound (C) selected from:

[In said general formula (b), R is a C12-C30 alkyl group or alkenyl group. ]

[In the general formula (c), m is 1 or 2, and R is an alkyl group having 10 to 40 carbon atoms or an alkenyl group having 10 to 40 carbon atoms. When m is 2, two Rs may be the same as each other or different from each other. ]

[2] In the base oil (A), the fatty acid (B) represented by the following general formula (b), the compound (C1) represented by the following general formula (c), and the amine salt (C2) of the compound (C1) 1) at least one acidic phosphate ester compound (C) selected from the method for producing a lubricating oil composition.

[In said general formula (b), R is a C12-C30 alkyl group or alkenyl group. ]

[In the general formula (c), m is 1 or 2, and R is an alkyl group having 10 to 40 carbon atoms or an alkenyl group having 10 to 40 carbon atoms. When m is 2, two Rs may be the same as each other or different from each other. ]

  The lubricating oil composition for a shock absorber of the present invention has a small friction coefficient between a rubber material and a metal, and has an excellent friction reducing effect.

It is the schematic of the testing machine used in order to perform a reciprocating friction test in a present Example.

  In the present specification, the kinematic viscosity and the viscosity index at a predetermined temperature mean values measured according to JIS K2283: 2000.

[Lubricating oil composition for shock absorber]
The lubricating oil composition for shock absorbers of the present invention (hereinafter sometimes simply referred to as “lubricating oil composition”) includes a base oil (A) and a fatty acid (B) represented by the general formula (b) described below. And one or more acidic phosphate ester compounds (C) selected from the compound (C1) represented by the general formula (c) and the amine salt (C2) of the compound (C1).
In addition, the lubricating oil composition of 1 aspect of this invention may contain other additives for lubricating oil other than a component (B) and a component (C) in the range which does not impair the effect of this invention.

  In the lubricating oil composition of one embodiment of the present invention, the total content of components (A) and (B) is preferably 60.01% by mass or more based on the total amount (100% by mass) of the lubricating oil composition. More preferably, it is 70.01 mass% or more, More preferably, it is 75.01 mass% or more, More preferably, it is 80.01 mass% or more, Most preferably, it is 85.01 mass% or more, Usually, 100 mass% or less , Preferably 99.9% by mass or less, more preferably 99% by mass or less.

  In the lubricating oil composition of one embodiment of the present invention, the total content of components (A), (B) and (C) is preferably 65 based on the total amount (100% by mass) of the lubricating oil composition. % By mass or more, more preferably 75% by mass or more, further preferably 80% by mass or more, still more preferably 85% by mass or more, particularly preferably 90% by mass or more, and usually 100% by mass or less, preferably 99%. 0.9 mass% or less, more preferably 99 mass% or less.

  Hereinafter, the detail of each component contained in the lubricating oil composition for shock absorbers of this invention is demonstrated.

<Base oil (A)>
As base oil (A) used by this invention, any of mineral oil and synthetic oil may be sufficient, and the mixed oil which used together 2 or more types chosen from mineral oil and synthetic oil may be sufficient.

Mineral oil includes, for example, atmospheric residual oil obtained by atmospheric distillation of crude oil such as paraffinic mineral oil, intermediate mineral oil, and naphthenic mineral oil; distillate obtained by vacuum distillation of these atmospheric residual oils Mineral oil that has been subjected to one or more purification processes such as solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, etc .; Fischer-Tropsch method, etc. And mineral oil wax obtained by isomerizing the produced wax (GTL wax (Gas To Liquids WAX)).
These mineral oils may be used alone or in combination of two or more.

Synthetic oils include, for example, α-olefin homopolymers, or α-olefin copolymers (for example, α-olefin copolymers having 8 to 14 carbon atoms such as ethylene-α-olefin copolymers). α-olefin; isoparaffin; polyol ester, dibasic acid ester (for example, ditridecyl glutarate), tribasic acid ester (for example, 2-ethylhexyl trimellitic acid), phosphoric acid ester, etc .; polyphenyl ether, etc. And various ethers; polyalkylene glycols; alkylbenzenes; alkylnaphthalenes and the like.
These synthetic oils may be used alone or in combination of two or more.
Among these, the synthetic oil used in the present invention is preferably one or more synthetic oils selected from poly α-olefins, various esters, and polyalkylene glycols, and more preferably poly α-olefins.

The kinematic viscosity at 40 ° C. of the base oil (A), preferably 5 to 200 mm ² / s, more preferably 7~100mm ² / s, more preferably 9~60mm ² / s.
The kinematic viscosity at 100 ° C. of the base oil (A) is preferably 2.0 to 20.0 mm ² / s, more preferably 2.0 to 15.0 mm ² / s, and still more preferably 2.0 to 10. 0 mm ² / s, more preferably more a 2.0~7.0mm ² / s.
The viscosity index of the base oil (A) is preferably 70 or more, more preferably 80 or more, and still more preferably 90 or more.

  In the lubricating oil composition of one embodiment of the present invention, the content of the base oil (A) is preferably 60% by mass or more, more preferably 65% by mass, based on the total amount (100% by mass) of the lubricating oil composition. Or more, more preferably 70% by mass or more, still more preferably 75% by mass or more, particularly preferably 80% by mass or more, and preferably 99.99% by mass or less, more preferably 99.95% by mass or less, More preferably, it is 99.90 mass% or less.

<Fatty acid (B)>
The lubricating oil composition for a shock absorber of the present invention contains a fatty acid (B) represented by the following general formula (b).
In addition, a fatty acid (B) may be used independently and may use 2 or more types together.

  In said general formula (b), R is a C12-C30 alkyl group or alkenyl group.

The fatty acid (B) has an alkyl group or alkenyl group having 12 to 30 carbon atoms, as shown in the general formula (b).
Since it has a C12-30 alkyl group or alkenyl group, it is considered that the solubility of the fatty acid (B) and the base oil (A) is improved, and the friction reducing property is more easily exhibited. As a result, the lubricating oil composition for a shock absorber according to the present invention has a small coefficient of friction between a rubber material and a metal, and particularly when used in a shock absorber for a vehicle body such as a two-wheeled vehicle, the riding comfort of the vehicle body can be greatly improved. .

  In the general formula (b), R is an alkyl group or an alkenyl group having 12 to 30 carbon atoms. From the viewpoint of improving the solubility with the base oil (A), the carbon number is 12 or more, preferably 14 or more, more preferably 16 or more, and further preferably 18 or more. Further, the friction reducing property is more easily expressed more effectively, and the coefficient of friction between the rubber material and the metal of the obtained lubricating oil composition is reduced. From the viewpoint, it is 30 or less, more preferably 28 or less, and still more preferably 24 or less. The alkyl group and alkenyl group may be branched, but are preferably linear (linear alkyl group or linear alkenyl group).

  Examples of the fatty acid represented by the general formula (b) include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, linoleic acid, and linolenic acid, and stearic acid is particularly preferable.

  In the lubricating oil composition of one embodiment of the present invention, the content of the component (B) facilitates more effective expression of the friction reduction characteristics, and the friction coefficient between the rubber material and the metal of the resulting lubricating oil composition is increased. From the viewpoint of reducing the size, the total amount (100% by mass) of the lubricating oil composition is preferably 0.01 to 4.0% by mass, more preferably 0.05 to 3.0% by mass, and still more preferably 0.00. It is 05-2.0 mass%, More preferably, it is 0.07-1.5 mass%, Most preferably, it is 0.07-1.0 mass%.

<Acid phosphate ester compound (C)>
The lubricating oil composition of one embodiment of the present invention further facilitates effective expression of friction reduction characteristics, and from the viewpoint of reducing the coefficient of friction between the rubber material and the metal of the resulting lubricating oil composition, the following general formula It contains one or more acidic phosphate ester compounds (C) selected from the compound (C1) represented by (c) and the amine salt (C2) of the compound (C1).
In addition, an acidic phosphate ester type compound (C) may be used independently and may use 2 or more types together.
In the present invention, the amine salt (C2) includes a salt formed by reacting an amine present in the lubricating oil composition with the compound (C1) after compounding the compound (C1). It is.

[In the general formula (c), m is 1 or 2, and R is an alkyl group having 10 to 40 carbon atoms or an alkenyl group having 10 to 40 carbon atoms. When m is 2, two Rs may be the same as each other or different from each other. ]

  In addition, since m is 1 or 2 in the said general formula (c), the compound (C1) represented by the said general formula (c) is a compound represented by the following general formula (c-1) ( C11) or the compound (C12) represented by the following general formula (c-2).

[R and R ′ in the general formula (c-1) and R in the general formula (c-2) are each independently an alkyl group having 10 to 40 carbon atoms or an alkenyl having 10 to 40 carbon atoms. It is a group. R and R ′ are not distinguished from R in the general formula (c), and may be the same or different from each other. ]

  That is, the compound (C11) is an acidic phosphoric diester in which m in the general formula (c) is 2, and the compound (C12) is an acidic phosphoric acid in which m in the general formula (c) is 1. Monoester.

  As carbon number of the alkyl group and alkenyl group which can be selected as R and R 'in the said general formula (c), (c-1) and (c-2), Preferably it is 10-40, More preferably Is from 12 to 35, more preferably from 14 to 30, and even more preferably from 16 to 25. The alkyl group and alkenyl group may be branched, but are preferably linear (linear alkyl group or linear alkenyl group).

  Examples of the linear alkyl group that can be selected as R and R ′ in the general formulas (c), (c-1), and (c-2) include an n-decyl group, an n-undecyl group, and an n-dodecyl group. Group, n-tridecyl group, n-tetradecyl group, n-octadecyl group, n-tetracosanyl group, n-tetracontanyl group and the like.

Examples of the linear alkenyl group that can be selected as R and R ′ in the general formulas (c), (c-1), and (c-2) include groups represented by the following general formula (p).

In the general formula (p), x and y are each independently an integer of 0 or more, and 10 ≦ x + y + 3 ≦ 40. * Indicates a bonding position with an oxygen atom in the general formulas (c), (c-1), and (c-2).
In addition, as a value of "x + y + 3" which is carbon number of a linear alkenyl group, More preferably, it is 12-35, More preferably, it is 14-30, More preferably, it is 16-25.
x and y are each independently preferably 0 to 37, more preferably 1 to 30, further preferably 3 to 20, and still more preferably 4 to 12.

The amine constituting the amine salt (C2) is preferably an amine having an alkyl group having 1 to 40 carbon atoms, more preferably an amine having an alkyl group having 5 to 35 carbon atoms, and an alkyl group having 10 to 30 carbon atoms. The amine having is more preferable.
The alkyl group may be a linear alkyl group or a branched alkyl group.

  In the lubricating oil composition of one aspect of the present invention, from the viewpoint of facilitating the expression of friction reduction more effectively and reducing the coefficient of friction between the rubber material and the metal of the resulting lubricating oil composition, acidic phosphate ester The content of the system compound (C) is preferably 0.01 to 12.0 mass%, more preferably 0.10 to 10.0 mass%, based on the total amount (100 mass%) of the lubricating oil composition. More preferably, it is 0.30-7.0 mass%, More preferably, it is 0.50-5.0 mass%, Most preferably, it is 0.90-3.0 mass%.

  In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of reducing the coefficient of friction between the rubber material and the metal of the resulting lubricating oil composition and obtaining excellent friction reducing properties, the component (B) and the component (C The content ratio [(B) / (C)] is preferably 1/99 to 50/50, more preferably 5/95 to 40/60, and even more preferably 5/95 to mass ratio. 35/65, more preferably 5/95 to 30/70, and particularly preferably 5/95 to 25/75.

  In one embodiment of the present invention, when the acidic phosphate ester compound (C) contains both the compound (C1) and the amine salt (C2) of the compound (C1), the component (C1) and the component ( The content ratio [(C1) / (C2)] to C2) is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, and even more preferably 25/75 to mass ratio. 75/25, more preferably 30/70 to 70/30, and particularly preferably 35/65 to 65/35.

In one embodiment of the present invention, the acidic phosphate compound (C) includes an acidic phosphate diester compound (Cx) composed of an amine salt of the compound (C11) and an acidic salt composed of an amine salt of the compound (C12). The phosphoric acid monoester compound (Cy) may be contained together.
In that case, the content ratio [(Cx) / (Cy)] of the acidic phosphoric diester compound (Cx) and the acidic phosphoric monoester compound (Cy) is a mass ratio, preferably 1/99 to 99/1, more preferably 5/95 to 95/5, still more preferably 10/90 to 90/10.
Note that in one embodiment of the present invention, the acidic phosphate ester compound (C) includes an acidic phosphate diester compound (Cx) composed of the compound (C11) and an amine salt thereof, a compound (C12) and an amine salt thereof. The acidic phosphoric acid monoester compound (Cy) may be contained together.

<Other additives>
The lubricating oil composition of one aspect of the present invention facilitates more effective expression of friction reducing properties, and from the viewpoint of reducing the coefficient of friction between the rubber material and the metal of the resulting lubricating oil composition, Various additives may be contained. In addition, these additives may be used independently and may use 2 or more types together.

(Fatty acid amide)
As the fatty acid amide, for example, an acid amide obtained by reacting a carboxylic acid and an amine is preferable.
Examples of carboxylic acids include straight-chain or branched-chain saturated or unsaturated monocarboxylic acids, and their carbon number facilitates more effective expression of friction-reducing properties, and the resulting lubricating oil composition rubber. From the viewpoint of reducing the coefficient of friction between the material and the metal, it is preferably 7 to 30, and more preferably 8 to 24. Among these, oleic acid and (iso) stearic acid are preferable as carboxylic acids.

  Examples of the amines include alkyl amines, alkanol amines, polyalkylene polyamines, etc. From the viewpoint of fatty acid amines having excellent solubility in the base oil (A), alkyl amines and polyalkylene polyamines are preferred, Alkylene polyamines are more preferred.

Examples of the alkylamine include primary aliphatic alkylamines such as monomethylamine, monoethylamine, monopropylamine, monobutylamine, monopentylamine; dimethylamine, methylethylamine, diethylamine, methylpropylamine, ethylpropylamine and the like. Grade aliphatic alkylamines and the like.
Examples of the alkanolamine include monomethanolamine, monoethanolamine, monopropanolamine, monobutanolamine, dimethanolamine, methanolethanolamine, diethanolamine, methanolpropanolamine, ethanolpropanolamine, dipropanolamine and the like.

As a polyalkylene polyamine, the compound represented by the following general formula (d-1) is preferable.

In the general formula (d-1), R ^d independently represents an alkylene group having 2 to 4 carbon atoms, and z represents an integer of 2 to 6. The plurality of R ^d may be the same as each other or different from each other.
The alkylene group having 2 to 4 carbon atoms, an ethylene group _(-CH 2 CH ₂ -) and propylene group _{(-CH 2 CH 2 CH 2 -} ) are preferable, and more preferably an ethylene group.

  Specific examples of the compound represented by the general formula (d-1) include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, tetrapropylenepentamine, and hexabutyleneheptamine. Is mentioned.

  A suitable combination of these carboxylic acids and amines includes a reaction product of isostearic acid and tetraethylenepentamine.

When the fatty acid amide is used, the content thereof is preferably 0.01 to 5.0% by mass, more preferably 0.05 to 4.0% by mass, based on the total amount (100% by mass) of the lubricating oil composition. %.
In this case, the content ratio [(D) / (B)] between the fatty acid amide (D) and the component (B) is preferably 10/99 to 95/5, more preferably 30/70 in terms of mass ratio. ~ 90/10.

(Fluorinated silicone)
The lubricating oil composition of one embodiment of the present invention may further contain a fluorinated silicone (E) from the viewpoint of improving antifoaming properties.
Examples of the fluorinated silicone include fluorine-containing organopolysiloxanes such as trifluoropropylmethyl silicone. In addition, a fluorinated silicone may be used independently and may use 2 or more types together.

When using the said fluorinated silicone, as content, Preferably it is 0.001-5.0 mass%, More preferably, it is 0.005-2.0 mass%.
The lubricating oil composition of one embodiment of the present invention may contain an antifoaming agent other than fluorinated silicone, and examples thereof include silicone oils such as organopolysiloxane.

(Seal Sweller)
The lubricating oil composition according to one aspect of the present invention is further added to a seal swirler (an additive having an effect of expanding the material of the seal, and the seal is hardened by other specific components). In this case, it is possible to prevent the seal from being cured. Examples of the seal sweller include a sulfur seal sweller.

When the seal sweller is used, the content thereof is preferably less than 1.5 mass%, more preferably less than 1.2 mass%, based on the total amount (100 mass%) of the lubricating oil composition.
In addition, the lower limit of the content when adding seal sweller is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition. .

<Other lubricant additives>
The lubricating oil composition of one embodiment of the present invention may further contain a component (B), a component (C), and an additive for lubricating oil other than the above-described components within a range not impairing the effects of the present invention.
Examples of such lubricating oil additives include viscosity index improvers, pour point depressants, ashless detergent dispersants, metal detergents, antioxidants, extreme pressure agents, antiwear agents, rust inhibitors, A metal deactivator etc. are mentioned.
These various additives for lubricating oil may be used alone or in combination of two or more.

  Each content in the case of using these additives for lubricating oil can be appropriately adjusted within a range not impairing the effects of the present invention, but based on the total amount (100% by mass) of the lubricating oil composition, Usually, it is 0.001-10 mass%, Preferably it is 0.005-8 mass%, More preferably, it is 0.01-5 mass%.

  In the lubricating oil composition of one embodiment of the present invention, the total content of these additives for lubricating oil is preferably 0 to 35% by mass based on the total amount (100% by mass) of the lubricating oil composition. More preferably, it is 0-25 mass%, More preferably, it is 0-20 mass%, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 mass%.

(Viscosity index improver)
Examples of the viscosity index improver include non-dispersed polymethacrylates, dispersed polymethacrylates, olefin copolymers (for example, ethylene-propylene copolymers), dispersed olefin copolymers, styrene copolymers. (For example, styrene-diene copolymer, styrene-isoprene copolymer, etc.).
The mass average molecular weight (Mw) of these viscosity index improvers is usually 500 to 1,000,000, preferably 5,000 to 800,000, more preferably 10,000 to 600,000. It is set as appropriate according to the type of coalescence.

(Pour point depressant)
Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene, and the like. Is preferably used.
The mass average molecular weight (Mw) of these pour point depressants is usually 50,000 to 150,000.

(Ashless cleaning dispersant)
Examples of the ashless detergent dispersant include imides such as succinimides and boron-containing succinimides, benzylamines, boron-containing benzylamines, and divalent carboxylic acid amides represented by succinic acid. . Among these, succinimides are preferable.

  Examples of succinimides include succinic acid having a polyalkenyl group such as a polybutenyl group having a number average molecular weight of 300 to 4,000, and ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and the like. Examples thereof include monoimides or bisimides of polyethylene polyamine, or boric acid-modified products thereof; Mannich reaction product of phenol, formaldehyde and polyethylene polyamine having a polyalkenyl group.

(Metal-based detergent)
Metal detergents include neutral metal sulfonate, neutral metal phenate, neutral metal salicylate, neutral metal phosphonate, basic metal sulfonate, basic metal phenate, basic metal salicylate, basic metal phosphonate, overbased Examples include metal sulfonates, overbased metal phenates, overbased metal salicylates, and overbased metal phosphonates.

(Antioxidant)
As the antioxidant, any one of known antioxidants conventionally used as an antioxidant for lubricating oils can be appropriately selected and used. For example, an amine-based antioxidant, a phenol-based antioxidant, and the like Antioxidants, molybdenum-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants and the like can be mentioned.
These antioxidants may be used alone or in combination of two or more.

Examples of the amine-based antioxidant include diphenylamine and diphenylamine-based antioxidants such as alkylated diphenylamine having an alkyl group having 3 to 20 carbon atoms; α-naphthylamine, phenyl-α-naphthylamine, and alkyl having 3 to 20 carbon atoms. And naphthylamine-based antioxidants such as substituted phenyl-α-naphthylamine having a group;
Examples of phenolic antioxidants include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, Monophenolic antioxidants such as isooctyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate Agents; Diphenolic antioxidants such as 4,4′-methylenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol); hindered phenolic Antioxidants; and the like.
Examples of the molybdenum-based antioxidant include molybdenum amine complex formed by reacting molybdenum trioxide and / or molybdic acid with an amine compound.
Examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate.
Examples of phosphorus antioxidants include phosphites.

(Extreme pressure agent, antiwear agent)
Examples of extreme pressure agents and antiwear agents include sulfur compounds such as sulfides, sulfoxides, sulfones, and thiophosphinates; halogen compounds such as chlorinated hydrocarbons, zinc dithiophosphate (ZnDTP), and dithiocarbamic acid. And organometallic compounds such as zinc (ZnDTC), sulfurized oxymolybdenum organophosphorodithioate (MoDTP), and sulfurized oxymolybdenum dithiocarbamate (MoDTC).

In addition, in the lubricating oil composition of one aspect of the present invention, other extreme extreme pressure agents or antiwear agents other than the component (C) are used as extreme pressure agents or antiwear agents within a range that does not impair the effects of the present invention. It may contain.
The content of such other phosphorus-based extreme pressure agent or antiwear agent is preferably 0 to 20 with respect to 100 parts by mass of the total amount of components (B) and (C) contained in the lubricating oil composition. It is 0 mass parts, More preferably, it is 0-10 mass parts, More preferably, it is 0-5 mass parts, More preferably, it is 0-2 mass parts, Most preferably, it is 0-0.1 mass part.

(Rust inhibitor)
Examples of the rust inhibitor include fatty acid, alkenyl succinic acid half ester, fatty acid soap, alkyl sulfonate, polyhydric alcohol fatty acid ester, fatty acid amine, oxidized paraffin, alkyl polyoxyethylene ether and the like.

(Metal deactivator)
Examples of the metal deactivator include benzotriazole compounds, tolyltriazole compounds, thiadiazole compounds, imidazole compounds, pyrimidine compounds, and the like.

[Various physical properties of lubricating oil composition]
The kinematic viscosity at 40 ° C. of the lubricating oil composition of one embodiment of the present invention is preferably ² to 100 mm ² / s, more preferably 5 to 60 mm ² / s, and still more preferably 7 to 40 mm ² / s.

The kinematic viscosity at 100 ° C. of the lubricating oil composition of one embodiment of the present invention is preferably 1.0 to 20.0 mm ² / s, more preferably 1.5 to 10.0 mm ² / s, and still more preferably Is 1.8 to 5.0 mm ² / s.

  The viscosity index of the lubricating oil composition of one embodiment of the present invention is preferably 100 or more, more preferably 120 or more, and still more preferably 150 or more.

The rubber-metal rubber friction coefficient (μ) of the lubricating oil composition of one embodiment of the present invention is preferably 0.070 or less, more preferably 0.060 or less, still more preferably 0.055 or less, and even more. Preferably it is 0.053 or less.
In addition, the value of said rubber friction coefficient ((micro | micron | mu)) means the value measured based on the "reciprocating friction test" as described in the below-mentioned Example.

[Use of lubricating oil composition]
The lubricating oil composition for a shock absorber of the present invention is used for lubricating a shock absorber member of a vehicle body such as a two-wheeled vehicle or a four-wheeled vehicle (particularly, for lubricating between a rubber material and a metal).
That is, the lubricating oil composition of the present invention is suitable as a lubricating oil composition for shock absorbers.
More specifically, the lubricating oil composition for the shock absorber can be used for any of a two-wheel, a four-wheel double-cylinder shock absorber, and a single-cylinder shock absorber, but is particularly preferably used for a two-wheel.

[Method of reducing friction of shock absorber]
Examples of the friction reducing method of the shock absorber include a method of adding the above-described lubricating oil composition for a shock absorber of the present invention to the shock absorber.
Examples of the shock absorber (shock absorber) include a double-cylinder shock absorber and a single-cylinder shock absorber.
The above friction reducing method is effective for all of these shock absorbers (shock absorbers), but particularly when there is rubber friction in the shock absorber (for example, when the sealing material and / or the bush is made of rubber). Excellent effect can be demonstrated.
In addition, the friction reducing method can reduce the friction with respect to any of the four-wheel and two-wheel shock absorbers, but is particularly excellent in the friction reducing effect of the shock absorber for two wheels.

[Method for producing lubricating oil composition for shock absorber]
Although there is no restriction | limiting in particular as a manufacturing method of the lubricating oil composition for shock absorbers of this invention, It is preferable that it is a method which has the following process (1).
Process (1): The process of mix | blending the fatty acid (B) represented by the said general formula (b), and an acidic phosphate ester type compound (C) with base oil (A).
In addition, the details (a suitable component, content, content ratio with other components, etc.) of the base oil (A), fatty acid (B), and acidic phosphate ester compound (C) used in the step (1) are as described above. It is as follows.
Moreover, in this process (1), each above-mentioned component may be contained further and additives for lubricating oil other than these may be contained.
Details of these components (preferred components, content, content ratio, etc.) are also as described above.

Specifically, after adding an additive for lubricating oil to a base oil including a mineral oil base oil, the mixture is stirred by a known method and the components (B) and (C) are mixed in the base oil (A). It is preferable to uniformly disperse the additive for lubricating oil.
In addition, from the viewpoint of uniformly dispersing the additive for lubricating oil such as component (B) and component (C), the temperature of the base oil (A) is increased to 40 to 70 ° C., and then the additive for lubricating oil is blended. More preferably, the mixture is stirred and dispersed uniformly.

  In the middle and after the completion of this step (1), part of component (B), component (C) and other components may be modified, or two components may react with each other to produce another component. The obtained lubricating oil composition also corresponds to the lubricating oil composition obtained by the method for producing a lubricating oil composition for a shock absorber according to the present invention, and belongs to the technical scope of the present invention.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples. In addition, the measuring method or evaluation method of various physical properties is as follows.

<Measuring method of various physical properties of mineral oil base oil or lubricating oil composition>
(1) Kinematic viscosity at 40 ° C. and 100 ° C. Measured according to JIS K2283: 2000.
(2) Viscosity index Measured according to JIS K2283: 2000.

Example 1, Comparative Examples 1-2
After preparing various mineral oils with the types and blending amounts shown in Table 1 to obtain base oils (i) to (iii), lubricating oil additives of the types and blending amounts shown in Table 1 were added to lubricate. Oil compositions (I) to (III) were respectively prepared.
The mineral oil and lubricating oil additives listed in Table 1 used in Examples and Comparative Examples are as follows.

<Mineral oil>
Naphthenic 60N mineral oil: 40 ° C. kinematic viscosity = 9.03 mm ² / s, 100 ° C. kinematic viscosity = 2.23 mm ² / s, viscosity index = 26.
Paraffinic 60N mineral oil: 40 ° C. kinematic viscosity = 9.92 mm ² / s, 100 ° C. kinematic viscosity = 2.71 mm ² / s, viscosity index = 114.
100N mineral oil: 40 ° C. kinematic viscosity = 21.0 mm ² / s, 100 ° C. kinematic viscosity = 4.47 mm ² / s, viscosity index = 127.

<Additive for lubricating oil>
-Acid phosphate ester compound: A mixture of dioleyl acid phosphate and monooleyl acid phosphate represented by the following formula.

Fatty acid: stearic acidPMA: polymethacrylate (mass average molecular weight (Mw): 550,000)
-Other additives: phenolic antioxidants, etc.

Regarding the base oils (i) to (iii) prepared in Examples and Comparative Examples, various physical property values were measured based on the above measurement methods. Further, for the prepared lubricating oil compositions (I) to (III), various physical property values were measured based on the above measurement method, and the following reciprocating friction test was performed.
These results are shown in Table 1.

[Reciprocating friction test]
The rubber friction coefficient between the rubber material and the metal when using the lubricating oil compositions prepared in Examples and Comparative Examples was measured using the testing machine shown in FIG.
Specifically, in the testing machine shown in FIG. 1, hemispherical rubber (nitrile rubber) and hard Cr (through the sample oil which is the lubricating oil composition prepared in the examples and comparative examples under the following test conditions. The rubber friction coefficient (μ) was determined from the maximum value of the frictional force by reciprocally sliding the chrome-plated steel sheet with the load. Test conditions are shown below.
(Test conditions)
・ Temperature: 25 ℃
・ Amplitude: ± 10mm (rectangular wave)
・ Load: 0.1kgf (0.98N)
-Upper test piece: hemispherical rubber (NBR (nitrile rubber))
・ Lower test piece: Hard Cr plated steel plate ・ Sample oil volume: 1ml applied ・ Speed: 10mm / s

The lubricating oil composition (I) prepared in Example 1 has a value of the coefficient of rubber friction between the rubber material and the metal as compared with the lubricating oil compositions (II) and (III) prepared in Comparative Examples 1 and 2. Was low.
Therefore, the lubricating oil composition (I) is considered to be a lubricating oil composition that can greatly improve the riding comfort of the vehicle body when used in a shock absorber of a vehicle body such as a motorcycle.

Claims (7)

Selected from base oil (A), fatty acid (B) represented by the following general formula (b), compound (C1) represented by the following general formula (c) and amine salt (C2) of compound (C1) A lubricating oil composition for a shock absorber, comprising at least one acidic phosphate ester compound (C).

[In said general formula (b), R is a C12-C30 alkyl group or alkenyl group. ]

[In the general formula (c), m is 1 or 2, and R is an alkyl group having 10 to 40 carbon atoms or an alkenyl group having 10 to 40 carbon atoms. When m is 2, two Rs may be the same as each other or different from each other. ]   The lubricating oil composition for a shock absorber according to claim 1, wherein the content of the component (B) is 0.01 to 4.0% by mass based on the total amount of the lubricating oil composition.   The lubricating oil composition for a shock absorber according to claim 1 or 2, wherein component (B) comprises stearic acid.   The lubricating oil composition for a shock absorber according to any one of claims 1 to 3, wherein R in the general formula (b) is an alkyl group or an alkenyl group having 12 to 24 carbon atoms.   The content ratio [(B) / (C)] of the component (B) and the component (C) is 1/99 to 50/50 in terms of mass ratio. Lubricating oil composition for shock absorbers.   The lubricating oil composition for a shock absorber according to any one of claims 1 to 5, which is used for a shock absorber of a motorcycle. The base oil (A) is selected from the fatty acid (B) represented by the following general formula (b), the compound (C1) represented by the following general formula (c), and the amine salt (C2) of the compound (C1) The manufacturing method of the lubricating oil composition for shock absorbers which has the process of mix | blending with 1 or more types of acidic phosphate ester type compounds (C).

[In said general formula (b), R is a C12-C30 alkyl group or alkenyl group. ]

[In the general formula (c), m is 1 or 2, and R is an alkyl group having 10 to 40 carbon atoms or an alkenyl group having 10 to 40 carbon atoms. When m is 2, two Rs may be the same as each other or different from each other. ]