WO2008038667A1 - Lubricating oil composition for buffers - Google Patents

Abstract

A lubricating oil composition for buffers in which a base oil comprising a mineral oil and/or a synthetic oil is blended with (A) a phosphate-type compound and/or a phosphite-type compound having a hydrocarbon group carrying 2 to 18 carbon atoms and (B) a secondary amine compound represented by the general formula (I): (I) wherein R1 and R2 represent each an alkyl group carrying 1 to 18 carbon atoms, an alkenyl group carrying 2 to 18 carbon atoms or a cycloalkane structure-containing group carrying 5 to 18 carbon atoms, or these groups may be bonded together to form a cyclic structure having 3 to 6 carbon atoms in the cycle. It is a lubricating oil composition for buffers which elevates the frictional force between seal and steel in an automotive buffer to thereby improve the driving stability during running at high speed and also improve the riding comfort.

Description

 Specification

 Lubricating oil composition for shock absorbers

 Technical field

 [0001] The present invention relates to a lubricating oil composition for shock absorbers. More specifically, the present invention increases the frictional force between the shock absorber (shock absorber / steel of the automobile) and improves the driving stability during high-speed driving of the automobile, and also improves the ride comfort. The present invention relates to a lubricating oil composition for shock absorbers, which has a small increase in frictional force and steel / steel friction coefficient.

 Background art

 [0002] Lubricants for automobile shock absorbers are mainly used for the purpose of suppressing vibrations in order to exhibit an optimal damping force for a vehicle and maintain steering stability. In particular, the highway network has been completed recently, and the rate of high-speed driving has increased compared to the past. Therefore, there is an increasing demand for vehicles that exhibit high-speed driving stability and superior performance in avoiding danger. However, with current vehicles in Japan, unstable rolling occurs when the steering wheel is turned to change lanes at a speed of 100 to 200 km / h, resulting in poor body stability and danger. Problems such as a long avoidance distance necessary for avoidance arise.

 As a result of research, this cause is related to the magnitude of the frictional force in sliding parts such as oil seals and piston rods, piston bands, and cylinders at minute amplitudes in shock absorbers. In high-speed driving, vibration shifts to tires, springs, shock absorbers, and vehicle bodies, resulting in slight vibration. This vibration usually has a stroke length of about 0.4-2. Omm and a repetition rate of 1.5--15. Such a condition is a condition in which the damping force of the shock absorber is not easily generated, so that the vibration damping action is not sufficiently exhibited. As a result, if the friction force at the beginning of sliding of the sliding part such as the oil seal and the piston rod or the piston band and the cylinder is small, the posture of the vehicle body easily tilts and deteriorates the stability.

[0004] Therefore, in order to solve such a problem, it is considered that the frictional force of the sliding portion such as the oil seal of the shock absorber lubricating oil, the piston rod, the piston band, and the cylinder may be increased. However, simply increasing the friction force may cause oil leakage due to oil seal wear, increased piston band and cylinder wear, and increased bearing and rod wear. . Therefore, it is required to increase the frictional force of sliding parts such as piston rod and oil seal, piston band and cylinder without impairing the wear resistance.

 Furthermore, the ride comfort is empirically determined by the friction coefficient at a specific low speed measured using a Pounden type reciprocating friction tester and the friction coefficient ^ at a specific high speed.

 L H

 It is known to be good if it is less than / μ force.

 L H

[0005] A lubricating oil composition suitable for use in automobile shock absorbers is disclosed in which dithiophosphoric acid diester 0.;! To 1.0 wt% is blended with respect to the lubricating base oil based on the total weight of the composition. In addition, as a lubricating oil composition for automobile shock absorbers, (A) an amine salt of an acidic phosphoric acid monoester based on the total weight of the lubricating oil base oil. . -0 3 wt _^0/0, (B) poly Anore Ke Nino record Nono click acid imide 0.5;!. ~ 0.6 weight _^0/0 and (C) an acidic phosphite diester 0.3 to 0 8 weight % Is disclosed (for example, see Patent Document 2).

 In these lubricating oil compositions, although the friction force between the seal and steel is large, there is no provision for the ratio.

 Further, the lubricating base oil contains [1] at least one nitrogen selected from (A) a specific aliphatic primary amine and (B) a succinimide having a hydrocarbon group having 8 to 30 carbon atoms. And (2) (C) a phosphate ester having a branched hydrocarbon group having 3 to 10 carbon atoms and (D) a phosphate ester having an (alkyl) aryl group having 6 to 18 carbon atoms. There is disclosed a hydraulic fluid composition for a shock absorber comprising at least one phosphorus-containing compound selected from among the above classes (for example, see Patent Document 3). Such a combination of a phosphorus compound and a nitrogen-containing compound is a force S, which has been used in the past for the purpose of stabilizing the phosphorus compound and reducing the frictional force. There is no mention of increasing power and improving the ratio.

[0006] Patent Document 1: Japanese Unexamined Patent Publication No. 2003-55681

 Patent Document 2: Japanese Patent Laid-Open No. 2003-147379

 Patent Document 3: Japanese Patent Laid-Open No. 2002-194376

 Disclosure of the invention

Problems to be solved by the invention [0007] Under such circumstances, the present invention increases the friction force between the seal / steel of the automobile shock absorber (Shockabsono and improves the steering stability during high-speed driving of the automobile. An object of the present invention is to provide a lubricating oil composition for a shock absorber that improves ride comfort and has a small increase in the coefficient of friction between steel and steel.

 Means for solving the problem

[0008] As a result of intensive studies to develop a lubricating oil composition for a shock absorber having the above-mentioned preferable properties, the present inventors have found that a specific phosphate ester-based compound and / or phosphite ester is contained in the base oil. By combining and combining a specific compound and a specific secondary amine compound

And found that the purpose can be achieved. The present invention has been completed based on strength and knowledge.

 That is, the present invention

 (1) a base oil composed of mineral oil and / or synthetic oil; and (A) a phosphate ester compound and / or a phosphite ester compound having a hydrocarbon group having 2 to 18 carbon atoms; ) —General formula (I)

[0009] [Chemical 1]

NH ... hi)

 R

[Wherein R ¹ and R ² each represent a carbon number;! To 18 alkyl group, 2 to carbon number; 18 alkenyl group or 5 to 18 carbon cycloalkane structure-containing group, They may be the same or different, and may be bonded together to form a cyclic structure having 3 to 6 ring carbon atoms with a nitrogen atom as a heteroatom. ]

[0010] A lubricating oil composition for a shock absorber, comprising a secondary amine compound represented by the formula:

 (2) The lubricating oil for shock absorbers according to the above (1), wherein the phosphoric acid ester compound having a hydrocarbon group having 2 to 18 carbon atoms is an acidic phosphate ester having one or two hydrocarbon groups Composition,

(3) The phosphorous acid stealth compound having a hydrocarbon group having 2 to 18 carbon atoms is an acidic phosphite diester having two such hydrocarbon groups, as described in (1) or (2) above Lubricating oil composition for shock absorbers, (4) Based on the total amount of the composition, the above (1) to (3), wherein the phosphoric acid ester compound and / or phosphite ester compound of (A) is blended in an amount of 0 to 0% by mass; The lubricating oil composition for a shock absorber according to any one of the items,

 (5) Based on the total amount of the composition, the secondary amine compound of (B) is blended in an amount of 0.05 to 5% by mass. An oil composition, and

 (6) Further, among ashless detergents, metal detergents, lubricity improvers, antioxidants, antifungal agents, metal deactivators, viscosity index improvers, pour point depressants and antifoaming agents The lubricating oil composition for a shock absorber according to any one of the above (1) to (5), which is formed by blending at least one selected from:

 Is to provide.

 The invention's effect

 [0011] According to the present invention, the frictional force between the shock absorber (shock absorber and the steel in the shock absorber) is increased, the driving stability at the time of high-speed driving of the vehicle is improved, and the riding comfort is also improved. Therefore, the increase in the friction coefficient between steel and steel is small!

 BEST MODE FOR CARRYING OUT THE INVENTION

[0012] The lubricating oil composition for shock absorbers of the present invention (hereinafter sometimes simply referred to as a lubricating oil composition) improves the handling stability during high-speed driving of an automobile and also improves the ride comfort. It was developed for the purpose.

 In order to improve steering stability during high-speed driving, it is important to increase the frictional force between the seal and steel, and in order to improve ride comfort, it is measured using a Pounden-type reciprocating friction tester. 1.Friction coefficient at low speed of Omm / s and 3.

 The ratio to the coefficient of friction at high speed / a is preferably less than a force. And

 H L H

 It is desirable to satisfy these conditions, maintain the wear resistance of the sliding part, and keep the friction coefficient between steel and steel low.

In order to satisfy the above-mentioned requirements, the lubricating oil composition of the present invention comprises (A) a phosphate ester-based hydrocarbon having a hydrocarbon group having 2 to 18 carbon atoms as an essential component in the base oil as shown below. A compound and / or a phosphite compound, and (B) a secondary amine having a specific structure It is characterized by containing a compound.

[0013] As the base oil in the lubricating oil composition of the present invention, mineral oil or synthetic oil is usually used. Examples of mineral oils that are not particularly limited with regard to the types of mineral oils and synthetic oils include, for example, paraffin-based mineral oils, intermediate-based mineral oils, or naphthenic oils obtained by ordinary refining methods such as solvent refining and hydrogenation refining. Examples include base mineral oils.

 Synthetic oils include, for example, polybutene, polyolefin [α-olefin (co) polymer]], various esters (eg, polyol ester, dibasic acid ester, phosphoric acid ester, etc.), various ethers (eg, In the present invention, the mineral oil may be used singly or in combination of two or more thereof. Further, the above synthetic oils may be used alone or in combination of two or more. Further, one or more mineral oils and one or more synthetic oils may be used in combination.

The lubricating oil composition of the present invention is mainly used as a shock absorber oil for cars intended for riding, and the viscosity of the base oil is 2.0-15. Range of Omm ² / s Force ^{s is} preferable, 4.0 to 9. Omm ² / s is more preferable.

[0014] In the lubricating oil composition of the present invention, the phosphate ester compound and / or the phosphite compound used as the component (A) has a hydrocarbon group having 2 to 18 carbon atoms in the molecule. The hydrocarbon group having 2 to 18 carbon atoms includes an alkyl group and an alkenyl group having 18 to 18 carbon atoms, 6 to 6 carbon atoms, an aryl group having 18 carbon atoms, and 7 to 18 carbon atoms. Examples include an aranolyl group. Examples of the alkyl group and alkenyl group may be linear, branched or cyclic. Examples thereof include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, sec —Butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, cyclopentyl groups, and cyclohex Xyl, aryl, propenyl, various butyr, various hexenyl, various octatur, various decenyl, various dodecenyl, various tetradecenyl, various hexadecenyl, various octadecenyl, cyclopentyl, Cyclohexenyl group Etc.

 Examples of the aryl group having 6 to 18 carbon atoms include phenyl group, tolyl group, xylyl group, and naphthyl group, and examples of the aralkyl group having 7 to 18 carbon atoms include benzyl group, phenethyl group, Examples thereof include naphthylmethyl group, methylbenzyl group, methylphenethyl group, and methylnaphthylmethyl group.

[0015] Examples of the phosphate ester compound used in the present invention include acidic phosphate monoester, acidic phosphate diester, and phosphate triester.

 Examples of acidic phosphoric acid monoesters include monoethyl acyl phosphate, mono n proprino rare acid phosphate, mono n butyno rare acid phosphate, mono 2-ethino red phosphate, mono noremicino rare acid phosphate, mono stearino rare acid phosphate. And monooleyl acid phosphate.

 Examples of acidic phosphoric acid diesters include di-n-butyl acid phosphate,

9-octadecenyl acid phosphate (Georail acid phosphate).

[0016] Examples of the triestenole phosphate include triaryl phosphate, trialkyl phosphate, trianolalkylaryl phosphate, triarylalkyl phosphate, trialkenyl phosphate, and the like. Examples thereof include triphenyl phosphate, tricresyl phosphate, benzil phosphate, and the like. Noresiferino renophosphate, ethinoresifu eninorephosphate, tributinorephosphate, ethinoresibutinorephosphate, credinoresifu eninorephosphate, dicresino renoenophosphate, ethylphenyl diphenyl phosphate, di ( Ethylphenyl) phenyl phosphate, propinorepheninoresifenenophosphate, di (propinorepheninole) phenenophosphate, toretinorefenenophosphate DOO, tripropinoin Les phenylene Honoré phosphate, Buchinorefu Eninorejifue two Norehosufeto, di (Buchinorefue two Honoré) phenylene Norehosufeto, Toribuchinore Hue Nino les phosphate, carboxymethyl Honoré phosphate birds, (Kishinore to 2 Echinore) tri Hosufue one 卜, 卜 デ レ 卜 卜 卜 ラ 卜 卜 ラ ラ ラ ラ 卜 卜 卜 卜 ミ リ 卜 卜 卜 卜 卜 卜 卜 卜 卜 卜.

 Among these phosphoric acid ester compounds, acidic phosphoric acid monoester and acidic phosphoric acid diester are preferable in terms of performance.

On the other hand, as the phosphite compound, for example, acidic phosphite diester and phosphite triester can be used.

 Examples of acidic phosphite diesters include di-n-butyl hydrogen phosphite, di-2-ethylhexyl hydrogen phosphite, didecyl hydrogen phosphite, didodecyl hydrogen phosphite (dilauryl hydrogen phosphite). , Dioctadecyl hydrogen phosphite (distearyl hydrogen phosphite), di-9 octadecenyl hydrogen phosphite (dioleyl hydrogen phosphite), diphenilno, idrogen phosphite, etc. Can be mentioned.

 Examples of phosphorous acid triesters include triethyl phosphite, tri-n-butyl phosphate, triphenyl phosphite, tricresyl phosphite, tri (noylpheninole) phosphite, and tri (2-ethylhexyl). Examples thereof include phosphite, tridecyl phosphite, trilauryl phosphite, trioleyl phosphite and the like.

[0018] Among the phosphite compounds, it is preferable from the point of view such as acid phosphite diester power performance.

 In the lubricating oil composition of the present invention, as the component (A), one or more of the phosphate ester compounds may be used! /, And one or more of the phosphite compounds may be used. Or, one or more of the phosphoric ester compounds may be used in combination with one or more of the phosphorous ester compounds! /.

The blending amount of component (A) is preferably in the range of 0.0;! To 4% by mass based on the total amount of the composition. If the blending amount is within the above range, the wear resistance of the sliding portion is sufficient, and the requirements required for the above-mentioned shock absorber are achieved by combination with the secondary amine (B) described later. Can be satisfied. A more preferable blending amount is 0.03 to 3% by mass. In particular, 0 .;! To 2% by mass is preferred.

In the lubricating oil composition of the present invention, the secondary amine compound used as the component (B) has the general formula (I)

[0020] [Chemical 2]

[0021] It has a structure represented by:

In the general formula (I), each of R ¹ and R ² represents an alkyl group having from 18 to 18 carbon atoms, an alkyl group having from 2 to 18 carbon atoms, an alkenyl group having 18 carbon atoms, or a group having from 5 to 18 carbon atoms and a cycloalkane structure-containing group. . R ¹ and R ² may be the same or different from each other to form a ring structure having 3 to 6 ring carbon atoms with a nitrogen atom as a heteroatom! /, Anyway!

 The alkyl group having from 18 to 18 carbon atoms may be linear or branched. For example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutanol group, Examples include sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, and the like.

 The alkenyl group having 2 to 18 carbon atoms may be linear or branched. For example, an aryl group, a propenyl group, various butyr groups, various hexenyl groups, various otatur groups, various types Examples include a decenyl group, various dodecenyl groups, various tetradecenyl groups, various hexadecenyl groups, and various octadecenyl groups.

 Examples of the cycloalkane structure-containing group having 5 to 18 carbon atoms include, for example, the general formula (Π)

[0022] [Chemical 3]

[0023] で表される、全炭素数 5〜； 18の基を挙げることができる。

And a group having a total carbon number of 5 to 18 and represented by:

In the general formula (Π), R ³ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, m is an integer from 0 to 3, and n is an integer from 0 to 0. Show.

The alkyl group having 1 to 8 carbon atoms in R ³ may be linear or branched. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl Nore group, sec-butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various octyl groups and the like.

The alkenyl group having 2 to 8 carbon atoms in R ³ may be either linear or branched, for example, a bur group, a allyl group, a propenyl group, various butyr groups, various penture groups, various varieties. A hexenyl group, various octatur groups, etc. are mentioned.

 Examples of the group having 5 to 18 carbon atoms represented by the general formula (Π) include, for example, a cyclopentyl group, a methylcyclopentyl group, a cyclopentylmethyl group, a 2-cyclopentylethyl group, a cyclohexyl group, and a methylcyclohexyl group. A cyclohexylmethyl group, a 2-cyclohexylethyl group, a cyclooctyl group, a cyclooctylmethyl group, a 2-cyclohexylethyl group, and the like.

R ¹ and R ² in the general formula (I) may be the same or different from each other, but are preferably the same from the viewpoint of ease of production. The R ¹ and R ² may be bonded to each other to form a cyclic structure having 3 to 6 ring carbon atoms having a nitrogen atom as a hetero atom. Formula (III)

[0024] [Chemical 4]

で表される環状アミンを挙げることができる。

The cyclic amine represented by these can be mentioned.

In the general formula (III), R ⁴ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and k represents an integer of 0 to 3.

The alkyl group having 1 to 8 carbon atoms and the alkenyl group having 2 to 8 carbon atoms in R ⁴ are Among them, the explanation is the same as for the alkyl group having 1 to 8 carbon atoms and the alkenyl group having 2 to 8 carbon atoms.

 Specific examples of the secondary amine compound used as the component (B) in the present invention include di-n-butylamine, di-n-hexylamine, di-n-octylamine, di-2-ethyl. Hexylamine, dilaurylamine, dimyristylamine, dipalmitylamine, distearylamine, dioleylamine, dicyclopentylamine, dicyclohexylamine, pyrrolidine, 2-methylpyrrolidine, piperidine, 2-methylbiperidine, hexamethyle Niimin and the like.

 In the lubricating oil composition of the present invention, as the component (B), the secondary amine compound represented by the general formula (I) may be used alone or in combination of two or more. Also good. The amount of component (B) is preferably in the range of 0.05 to 5% by mass based on the total amount of the composition. If this blending amount is within the above range, the phosphate ester compound and / or the phosphite compound as component (A) will have good stability against oxidative deterioration and storage stability. The required requirements can be satisfied, and the wear resistance of the sliding part is also good. A more preferable blending amount is 0.;! To 3% by mass, and particularly preferably 0.;! To 2% by mass.

 In addition, when a primary amine compound is used as the component (B), the above-mentioned requirements required for a shock absorber cannot be satisfied.

 [0027] In the lubricating oil composition of the present invention, various additives such as an ashless detergent dispersant, a metallic detergent, and a lubricity improver (( A) Other lubricant improvers other than A), antioxidants, anti-tacking agents, metal deactivators, viscosity index improvers, pour point depressants and antifoaming agents are added. be able to.

Here, as the ashless detergent dispersant, for example, succinimides, boron-containing succinic acid imides, benzylamines, boron-containing benzylamines, succinic acid esters, fatty acids or succinic acid can be used. Examples of metal detergents include neutral metal sulfonates, neutral metal phenates, neutral metal salicylates, neutral metal phosphonates, basic sulfonates, basic phenates, and bases. Salicylates, overbased sulfonates, overbased salicylates, overbased phosphonates and the like. These amounts of formulations, the lubricating oil based on the total amount of the composition, typically 0.1;! ~ 20 mass _^0/0, preferably 0.5 5; 10% by mass.

[0028] Examples of the lubricity improver include extreme pressure agents, antiwear agents, and oil agents, such as zinc dithiophosphate (ZnDTP), zinc dithiocarbamate (ZnDTC), and oximolybdesulfide HMoDTC). An organometallic compound is mentioned. These amounts are usually 0.05-5 mass based on the total amount of the lubricating oil composition. / ₀ , preferably ₀ ;! To 3% by weight.

 Further, sulfur-based extreme pressure agents such as sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dihydrocarbyl polysulfides, thiadiazole compounds, alkylthio-powered rubamoyl compounds, triazine compounds, thioterpene compounds, and dialkylthiodipropionate compounds. These blending amounts are usually 0.05 to 2% by mass based on the total amount of the lubricating oil composition.

 Furthermore, aliphatic saturated and unsaturated monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimanoic acid and hydrogenated dimer acid, hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid, lauryl alcohol, Aliphatic saturated and unsaturated monoalcohols such as oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine, oleylamine, aliphatic saturated and unsaturated monocarboxylic amides such as lauric acid amide, oleic acid amide, etc. These oil-based agents are mentioned. The blending amount of these oil-based agents is usually 0.01 to 10% by mass, preferably 0.;! To 5% by mass, based on the total amount of the lubricating oil composition.

[0029] As the antioxidant, amine-based antioxidants, phenol-based antioxidants and sulfur-based antioxidants conventionally used in lubricating oils can be used. These antioxidants can be used singly or in combination of two or more. Examples of amine-based antioxidants include monoalkyldiphenylamine compounds such as monooctyldiphenylamine and monononyldiphenylamine, 4, 4 'dibutyldiphenylamine, 4, 4'- Dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldi Dialkyldiphenylamine compounds such as phenylamine, tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, polyalkyldiphenylamine compounds such as tetranonyldiphenylamine, α-naphthylamine, phenyl Α α naphthylamine, butyl phenyl ル ー α naphthylamine, pentyl phenyl α naphthylamine, hexylphenyl α naphthylamine, heptyl phenynole α naphthinoreamine, octino refenore α naphthinoreamine

[0030] Examples of the phenolic antioxidant include monophenolic compounds such as 2,6 di-tert-butyl-4-methylphenol, 2,6-ditert-butyl-4-ethylphenol, 4,4'-methylenebis (2,6-ditert-butyl) And diphenol compounds such as 2,2-methylenebis (4-ethyl-6-tert butylphenol).

 Examples of sulfur-based antioxidants include 2,6 di-tertbutyl-4- (4,6 bis (octylthio) -1,3,5 triazine-2-ylamino) phenol, a reaction product of phosphorus pentasulfide and pinene, etc. And dialkylthiodipropionates such as dilauryl thiodipropionate and distearyl thiodipropionate. The amount of these antioxidants is usually about 0.01 to 10% by mass, preferably 0.03 to 5% by mass, based on the total amount of the lubricating oil composition.

[0031] Examples of the antifungal agent include metal sulfonates and succinic acid esters.

 The blending amount of these fungicides is usually about 0.0;! To 10% by mass, preferably 0.05 to 5% by mass, based on the total amount of the lubricating oil composition, from the viewpoint of the blending effect.

 Examples of the metal deactivator include benzotriazole and thiadiazole. The preferred blending amount of these metal deactivators is usually about 0.01 to about 10% by mass, preferably about 0.01 to about!% By mass, based on the total amount of the lubricating oil composition, from the viewpoint of the blending effect. It is.

Examples of the viscosity index improver include polymetatalylate, dispersed polymetatalylate, olefinic copolymer (for example, ethylene propylene copolymer), dispersed olefinic copolymer, and styrene copolymer. (For example, styrene-hydrogenated copolymer) Etc.

 The blending amount of these viscosity index improvers is usually about 0.5 to 35% by weight, preferably 1 to 15% by weight, based on the total amount of the lubricating oil composition, from the viewpoint of blending effects.

[0032] As the pour point depressant, polymethalate having a weight average molecular weight of about 50,000 to 150,000 is used.

 As the antifoaming agent, the antifoaming property is effectively exhibited and the riding comfort is improved by blending the high molecular silicone antifoaming agent, which is preferable to the high molecular silicone antifoaming agent. Examples of the high molecular silicone antifoaming agent include organopolysiloxane, and fluorine-containing organopolysiloxane such as trifluoropropylmethyl silicone oil is particularly preferable. This high molecular weight silicone antifoaming agent is preferably added in an amount of about 0.005 to 0.1% by mass based on the total amount of the composition from the viewpoint of the balance between the antifoaming effect and the economical efficiency. It is more preferable to add 08% by mass.

[0033] The lubricating oil composition for a shock absorber according to the present invention uses a powder reciprocating friction tester at a speed of 1. Omm / s and 3. Omm / s under the experimental conditions described below. When the friction coefficient and are measured, μ is preferably 0 · 4 or more, more preferably 0 · 5 or more.

L Η Η

 . If this is 0.4 or more, the steering stability during high-speed driving of the automobile is good.

 Η

 In addition, the μ / II ratio is preferably less than 1, more than 0.7 and less than 1.

L Η

 A force beam is preferred. If it is less than this / II force, the ride comfort is good and the

 L Η

 If it is above, there is little shock felt by the human body with good ride comfort, which is good.

 Furthermore, the steel / steel friction coefficient measured under the conditions described below is usually 0.3 or less, and a phosphate ester compound and / or a phosphite ester compound is added without adding a secondary amine compound. The increase in the coefficient of friction is small compared to when it is added! /.

[0034] As described above, the present invention is a lubricating oil composition comprising a base oil, components (Α) and (Β), and various additives as necessary. A lubricating oil composition comprising the components (ii) and (ii), and various additives as required.

 Example

[0035] Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples. • Pounden friction test (1)

 <Friction coefficient measurement between rail / steel>

 Testing machine: Pounden type reciprocating friction tester

 Experimental conditions

 Oil temperature: 20 ° C

 Load: 9.8N

 Stroke: 10mm

 Speed: 1. Omm / s, 3.0mm / s

 Friction frequency: 50 times

 Friction material: Upper rubber (A437)

 Lower chrome plate

 Under the above experimental conditions, the coefficient of friction at the speed of 1. Omm / s and the speed of 3. Omm / s

The coefficient of friction was measured and _β / _β was determined.

 H L Η

 • Pounden friction test (2)

 <Measurement of friction coefficient between steel and steel>

 Testing machine: Pounden type reciprocating friction tester

 Experimental conditions

 Oil temperature: 40 ° C

 Load: 9.8N

 Stroke: 10mm

 Speed: 3. Omm, s

 Friction frequency: 50 times

 Friction material: Upper sphere (SUJ-2)

 Lower SPCC board

 The coefficient of friction was measured under the above experimental conditions.

 Moreover, the kind of each component used for preparation of a lubricating oil composition is as follows.

(1) Base oil: paraffinic, 40 ° C kinematic viscosity 10mm ² / s

(2) Phosphorus compounds A—2: G n Butinore hydrogen phosphite

 A—3: G n Butinorea acid phosphate

 A—4: G-2-ethylhexyl hydrogen phosphite

 A-5: Di-2-ethylhexyl acid phosphate

 A-6: Mono-2-ethylhexyl acid phosphate

 A—7: Dilaurinorenoidogen phosphite

 A—8: Gioleino hydrogen phosphite

(3) Amino compounds

 B—1: Gee n-Butanolamine

 B-2: G-2-Ethinorehexynoleamine

 B—3: Product made by Lionaxo, trade name “armin 2C”, main ingredient dilaurylamine

B—4: Product name “Larmin 2HT”, main product distearylamine, manufactured by Lionaxo

B—5: Piperidine

 B-6: Dicyclohexylenoamine

 b—l: Monooleylamine

 (4) Other

 C-1: Polyimbutyrsuccinimide (ashless detergent / dispersant)

 C 2: 2, 6 G t-Butyl p Talesol (Antioxidant)

Examples;! To 19 and comparative examples;! To 6

 Lubricating oil compositions containing the components shown in Table 1 were prepared, and Pounden friction tests (1) and (2) were conducted.

 The powder friction test (1) was performed as described above, and the friction coefficient between and the seal / steel was measured, and the / 11 ratio was obtained. μ is preferably 0 · 4 or more, especially 0 · 7

H L Η Η

More than 1 is preferable. Also, the / ratio is preferably less than 1. The Pounden Test (2)

 L Η

The friction coefficient between steel / steel was measured as described above. In this case, the coefficient of friction between steel and steel in a composition comprising a phosphorus compound and an amine compound is measured. In the specified composition, the friction coefficient ^ between the steel and the steel without the amine compound is

 Ρ

Measured and further determined the / 11 ratio. The lower the better.

 (Ρ + Α) Ρ (Ρ + Α)

 [table 1]

 Table 1

 (Note) μ (ρ + Α): Friction coefficient between steel and steel in composition containing phosphorus compound and ammine compound

In the composition measured β ρ-. ( _{Ρ + Α} ), the coefficient of friction between steel and steel when no amine compound is included [Table 2] Table 1-2

 (Note) tl (p + A): Friction coefficient between steel and steel in compositions containing phosphorus compounds and amine compounds

p. U (Coefficient of friction between steel and steel in the case of the composition with _{P + W} measured without the amine compound 3]

Table 1-3

 (Note) U: Friction coefficient between steel and steel in composition containing phosphorus compound and ammine compound

μ _Ρ : μ (In the composition where _{P + w} was measured, steel rub between steel and steel when no amine compound is included 4]

Table 1-4

(Note) H _{(P + A} ): Steel / steel friction coefficient in compositions containing phosphorus and amine compounds

β ρ. 摩擦 ( _{P + A} ), the coefficient of friction between steel and steel when no amine compound is included

* 0.09: Value of a composition not containing an amine compound.

[0042] As can be seen from Table 1, all of the lubricating oil compositions of the present invention (Examples;! To 19)

 H

 Is as high as 0 · 55 or more (μ in Comparative Examples 1 to 6 is from 0.09 to 0.19), and the power μ ratio is less than 1

 H L / Η. Therefore, the driving stability at the time of high-speed driving of the automobile is good, the ride comfort is also good, and the force, the friction coefficient between steel / steel is small compared with the comparative example.

 Industrial applicability

[0043] The lubricating oil composition for a shock absorber according to the present invention is a combination of a specific phosphorus compound and an amine compound and is blended in a base oil, and increases the frictional force between a seal and steel in a shock absorber of an automobile. In addition to improving steering stability during high-speed driving, it also improves ride comfort. And force S.

Claims

The scope of the claims  [1] a base oil composed of mineral oil and / or synthetic oil; (A) a phosphate ester compound and / or a phosphite ester compound having a hydrocarbon group having 2 to 18 carbon atoms; and (B) — Formula (I) [Chemical R ¹ R ¹

[Wherein, R ¹ and R ² each represent an alkyl group having from 18 to 18 carbon atoms, from ² to 18 carbon atoms, an alkenyl group having 18 carbon atoms, or a group having from 5 to 18 carbon atoms; However, they may be the same or different and may be bonded together to form a cyclic structure having 3 to 6 ring carbon atoms having a nitrogen atom as a heteroatom. ]  A lubricating oil composition for a shock absorber comprising a secondary amine compound represented by the formula:  [2] A phosphate ester-based compound having a hydrocarbon group having 2 to 18 carbon atoms, the hydrocarbon group  2. The lubricating oil composition for a shock absorber according to claim 1, which is an acidic phosphate ester having one or two.  [3] The lubricating oil composition for a shock absorber according to claim 1, wherein the phosphite compound having a hydrocarbon group having 2 to 18 carbon atoms is an acidic phosphite diester having two such hydrocarbon groups. .  [4] The shock absorber according to claim 1, wherein the phosphoric acid ester compound and / or phosphite ester compound of (A) is blended in an amount of 0.0;! To 4% by mass based on the total amount of the composition. Lubricating oil composition.  [5] The lubricating oil composition for a shock absorber according to claim 1, comprising 0.05 to 5% by mass of the secondary amine compound (B) based on the total amount of the composition.  [6] Further, among ashless detergents, metal detergents, lubricity improvers, antioxidants, antifungal agents, metal deactivators, viscosity index improvers, pour point depressants and antifoaming agents 2. The lubricating oil composition for a shock absorber according to claim 1, comprising at least one selected from the group consisting of: