JP2000026883A - Grease composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grease compsn. improved in flaking resistance by compounding a lube base oil with an urea-based thickening agent, a sulfur- beased extreme pressure agent, and a specific perbasic zinc sulfonate. SOLUTION: A lube base oil having a kinematic viscosity at 100 deg.C of 2-40 mm2/s, pref. 3-20 mm2/s, and a viscosity index of 90 or higher, pref. 100 or higher, is compounded with 2-30 mass %, pref. 5-20 mass %, urea-based thickener of the formula: A-CONH-R1-NHCO-B, 2-40 mass %, pref. 5-35 mass %, sulfur- based extreme pressure agent of the formula: R6-(S)x-R7 having a sulfur content of 10-55 mass %, pref. 20-50 mass %, and 0.05-10 mass %, pref. 0.1-5 mass %, perbasic zinc sulfonate having a total value of 100-500 mgKOH/g, pref. 150-450 mgKOH/g. In the formulas, R1 is a divalent hydrocarbon group; A and B are each -NHR2, -NR3R4, or OR5; R2 to R5 are each a 6-20C hydrocarbon group; R6 and R7 are each 3-20C linear or branched alkyl, 6-20C aryl, or the like; and (x) is 2-6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease composition, and more particularly to a grease composition suitably used for a constant velocity joint.

[0002]

2. Description of the Related Art A constant velocity joint is a joint used for a drive transmission shaft from a transmission of an automobile to a tire. Types of constant velocity joints include fixed joints such as a bar field joint, a Zeppa joint, and an undercut free joint, and slide joints such as a double offset joint, a tripod joint, and a cross groove joint.
For these constant velocity joints, greases in which additives such as molybdenum disulfide and lead compounds are added to a base grease composed of a lubricating base oil and a lithium soap or a urea-based thickener have been mainly used. .

[0003] Greases for constant velocity joints are required to have properties such as flaking resistance, seizure resistance, wear resistance, and low friction. However, with the recent trend toward higher performance and higher grades of automobiles, greases that have been used in the past have become inadequate in performance. It is strongly desired.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a grease composition which is particularly excellent in flaking resistance.

[0005]

That is, according to the present invention, (A) 2 to 30% by mass of a urea-based thickener and (B) a sulfur-based extreme-pressure agent are added to a lubricating base oil based on the total amount of the composition. 0.1 ~
20% by mass, and (C) 100-500 mg of total base number
KOH / g overbased zinc sulfonate 0.05-1
A grease composition containing 0% by weight is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The lubricating base oil used in the present invention includes mineral oil and / or synthetic oil. The kinematic viscosity at 100 ° C. of the lubricating base oil is usually ^{2 to} 40 mm ² / s, preferably 3 to 20 m ² / s.
m ² / s. The viscosity index of a lubricating base oil is usually 90
The number is preferably 100 or more.

[0007] As a mineral oil, a lubricating oil fraction obtained by normal-pressure distillation and reduced-pressure distillation of a crude oil obtained by a method usually performed in a lubricating oil production process of a petroleum refining industry is subjected to solvent removal and solvent extraction. , Hydrogenolysis, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment and the like, followed by purification. As a synthetic oil,
For example, poly-α-olefins such as polybutene, 1-octene oligomer and 1-decene oligomer or hydrides thereof; ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-3-ethylhexyl sebacate and the like Polyesters such as trimethylolpropane caprylate, trimethylolpropaneperargonate, pentaerythritol-2-ethylhexanoate and pentaerythritol perargonate; alkyl naphthalene; alkyl benzene; polyoxyalkylene glycol; polyphenyl ether; dialkyl diphenyl ether A silicone oil; or a mixture thereof.

The component (A) used in the present invention is a urea thickener. As the component (A), a urea compound,
Examples thereof include urea / urethane compounds, urethane compounds, and mixtures thereof. Examples of the urea compound, urea / urethane compound and urethane compound include diurea compounds, triurea compounds, tetraurea compounds, polyurea compounds (excluding diurea compounds, triurea compounds and tetraurea compounds), urea / urethane compounds, diurethane compounds and mixtures thereof. And the like, preferably a diurea compound, a urea / urethane compound, a diurethane compound or a mixture thereof. More specifically, for example, a compound represented by the following formula (1) or a mixture thereof is preferable. A-CONH-R ¹ -NHCO-B (1) In the formula, R ¹ represents a divalent hydrocarbon group, A and B are the same or different groups, and are represented by -NHR ² , -NR ³ R ⁴ or OR ⁵ is shown. R ² , R ³ , R ⁴ and R ⁵ are the same or different groups and represent a hydrocarbon residue having 6 to 20 carbon atoms.

R ¹ in the formula (1) preferably has 6 carbon atoms.
To 20, and particularly preferably a divalent hydrocarbon residue having 6 to 15 carbon atoms. Examples of the divalent hydrocarbon residue include a linear or branched alkenylene group, a cycloalkylene group, and an aromatic group. Specific examples of R ¹ include an ethylene group, a 2,2-dimethyl-4-methylhexylene group, and a group represented by the following formula.

[0010]

Embedded image

Among them, a group represented by the following formula is particularly preferred.

[0012]

Embedded image

R ² , R ³ , R ⁴ and R ⁵ are linear or branched alkyl groups, linear or branched alkenyl groups, cycloalkyl groups, alkylcycloalkyl groups, aryl groups. , An alkylaryl group, an arylalkyl group and the like. Specifically, a hexyl group, a heptyl group,
Linear or branched alkyl groups such as octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, peptadecyl group, octadecyl group, nonadecyl group and eicosyl group A straight chain such as a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, a nonadecenyl group, and an eicosenyl group. Or a branched alkenyl group; a cyclohexyl group,
Methylcyclohexyl group, dimethylcyclohexyl group,
Ethylcyclohexyl group, diethylcyclohexyl group,
Propylcyclohexyl, isopropylcyclohexyl, 1-methyl-3-propylcyclohexyl, butylcyclohexyl, amylcyclohexyl, amylmethylcyclohexyl, hexylcyclohexyl, heptylcyclohexyl, octylcyclohexyl, nonylcyclohexyl, decylcyclohexyl , Undecylcyclohexyl group, dodecylcyclohexyl group, tridecylcyclohexyl group, alkylcycloalkyl group such as tetradecylcyclohexyl group; phenyl group, aryl group such as naphthyl group; toluyl group, ethylphenyl group, xylyl group, propylphenyl group, Alkylaryl groups such as cumenyl, methylnaphthyl, ethylnaphthyl, dimethylnaphthyl, and propylnaphthyl; benzyl, Rubenjiru group, an arylalkyl group such as ethylbenzyl groups. Among them cyclohexyl group, an octadecyl group, a toluyl group are particularly preferred.

In order to prepare these diurea compounds, urea / urethane compounds or diurethane compounds, for example, a diisocyanate represented by the formula OCN-R ¹ -NCO and a compound represented by the formula R ² NH ₂ , R ³ R ⁴ NH or R A compound represented by ⁵ OH or a mixture thereof is mixed with a base oil for 10 to 2 hours.
It is obtained by reacting at 00 ° C. On this occasion,
^{R 1, R 2, R 3} , R 4 and R ^5, R ^1, R in the formula (1)
² , R ³ , R ⁴ and R ⁵ are the same.

The lower limit of the content of the component (A) is 2% by mass, preferably 5% by mass, and the upper limit is 30% by mass, preferably 20% by mass, based on the total amount of the grease composition. When the content of the component (A) is less than 2% by mass, the effect as a thickener is small and the grease is not sufficiently formed. On the other hand, when the content exceeds 30% by mass, the grease becomes too hard to provide sufficient lubrication performance. Can not demonstrate.

The component (B) used in the present invention is a sulfur-based extreme pressure agent. Examples of the component (B) include one or more compounds selected from the group consisting of dihydrocarbine polysulfide and sulfurized fats and oils.

Dihydrocarbyl polysulfide is
It is a sulfur compound generally called polysulfide or sulfurized olefin, and specifically, a compound represented by the formula (2). R ^6- (S) x-R ⁷ (2) In the formula (2), R ⁶ and R ⁷ are the same or different groups, and are linear or branched having 3 to 20 carbon atoms. Alkyl group,
X represents an aryl group, an alkylaryl group or an arylalkyl group having 6 to 20 carbon atoms, and x represents 2 to 6, preferably 2
Shows the number of ~ 5. Specific examples of R ⁶ and R ⁷ include n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, and nonyl. Group,
Decyl group, undecyl group, dodecyl group, tridecyl group,
A linear or branched alkyl group such as a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl group; a phenyl group;
Aryl group such as naphthyl group; tolyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group , Dodecylphenyl, xylyl, ethylmethylphenyl, diethylphenyl, dipropylphenyl, dibutylphenyl, methylnaphthyl, ethylnaphthyl, propylnaphthyl, butylnaphthyl, dimethylnaphthyl, ethylmethylnaphthyl An alkylaryl group such as a diethylnaphthyl group, a dipropylnaphthyl group, a dibutylnaphthyl group (including all structural isomers); a benzyl group,
And arylalkyl groups such as phenylethyl group and phenylpropyl group (including all structural isomers).

Among them, R ⁶ and R ⁷ in the formula (2) are each independently an alkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 8 carbon atoms, an alkyl group derived from propylene, 1-butene or isobutylene; An aryl group or an arylalkyl group is preferred. Specifically, an isopropyl group, a branched hexyl group derived from a propylene dimer, a branched nonyl group derived from a propylene trimer,
Branched dodecyl group derived from pentamer, branched pentadecyl group derived from propylene pentamer, propylene 6
Branched octyl group derived from a dimer, sec-butyl group, tert-butyl group, branched octyl group derived from a 1-butene dimer, and branched octyl derived from an isobutylene dimer Group, branched dodecyl group derived from 1-butene trimer, branched dodecyl group derived from isobutylene trimer, branched hexadecyl group derived from 1-butene tetramer, isobutylene tetramer Alkyl groups such as a branched hexadecyl group derived from a compound (including all branched isomers); alkylaryl groups such as a phenyl group, a tolyl group, an ethylphenyl group, and a xylyl group (however, Arylalkyl groups such as a benzyl group and a phenylethyl group (including all isomers), and the like. Further, R in the formula (2)
⁶ and R ⁷ are each independently preferably a branched alkyl group having 3 to 18 carbon atoms derived from propylene or isobutylene, and a branched alkyl group having 6 to 15 carbon atoms derived from propylene or isobutylene is more preferable. Particularly preferred.

The sulfur content of the dihydrocarbyl polysulfide is not limited, but the sulfur content is usually preferably from 10 to 55% by mass, more preferably from 20 to 50% by mass, from the viewpoint of excellent extreme pressure performance.

The hardened fats and oils that can be used as the component (B) include, for example, animal and vegetable fats such as beef tallow, lard, fish fat, rapeseed oil, soybean oil; oleic acid, linoleic acid,
Unsaturated fatty acids such as linolenic acid or fatty acids extracted from animal and vegetable oils and fats; unsaturated fatty acid esters obtained by reacting these unsaturated fatty acids with various alcohols and acid chlorides;
Alternatively, those obtained by sulfidizing a mixture thereof or the like by an arbitrary method may be mentioned. Although the sulfur content of the hardened oil and fat is optional, the sulfur content is usually desirably 2 to 40% by mass, preferably 5 to 35% by mass from the viewpoint of excellent extreme pressure performance.

The lower limit of the content of the component (B) is 0.1% by mass, preferably 0.1% by mass, based on the total amount of the grease composition.
5% by mass; the upper limit is 20% by mass, preferably 10% by mass. If the content of the component (B) is less than 0.1% by mass, the anti-seizure property of the grease is not sufficient. On the other hand, if it exceeds 20% by mass, the anti-seizure performance corresponding to the added amount cannot be obtained.

The component (C) used in the present invention is an overbased zinc sulfonate. The lower limit of the total base number of the component (C) is 100 mgKOH / g, preferably 150 mgKO.
H / g, while the upper limit is 500 mg KOH / g,
Preferably it is 450 mgKOH / g. When the total base number of the component (C) is less than 100 mgKOH / g, the synergistic effect with the component (B) on the anti-flaking is not sufficient. On the other hand, it is difficult to obtain those having a total base number exceeding 500 mgKOH / g. is there. In the present invention, the total base number is defined in JIS K2501 "Petroleum products and lubricating oils-Neutralization number test method". Means the total base number measured by the perchloric acid method in accordance with

As the component (C), an overbased oil-soluble zinc sulfonate is preferred. The overbased oil-soluble zinc sulfonate means an overbased oil-soluble zinc sulfonate containing calcium carbonate and / or an overbased oil-soluble zinc sulfonate containing calcium borate.

The method of producing the calcium carbonate-containing overbased oil-soluble zinc sulfonate is optional. For example, a calcium base (calcium oxide or hydroxide) is dispersed in neutral (normal salt) zinc sulfonate. Alternatively, it can be produced by a method in which carbon dioxide gas is further blown to react the carbon dioxide gas with the calcium base to form a calcium carbonate dispersion in the system. The method for producing calcium borate-containing overbased oil-soluble zinc sulfonate is also optional, for example,
Disperse a calcium base (oxide or hydroxide of calcium) in neutral (normal salt) zinc sulfonate, and further add boric acid, borate or borate ester to form a calcium borate dispersion in the system. A method of producing, or a method of reacting boric acid, borate or borate with the calcium carbonate-containing overbased oil-soluble zinc sulfonate to convert calcium carbonate dispersed in the system into calcium borate, etc. Can be manufactured. These reactions are:
Usually, it is carried out in a solvent such as an aliphatic hydrocarbon solvent such as hexane; a hydrocarbon solvent such as xylene; and a light lubricating base oil.

The boric acid used in the method for producing the calcium-borate-containing overbased oil-soluble zinc sulfonate includes:
For example, orthoboric acid, metaboric acid, tetraboric acid and the like can be mentioned. Examples of the borate include alkali metal salts, alkaline earth metal salts, and ammonium salts of boric acid. Specifically, lithium borates such as lithium metaborate, lithium tetraborate, lithium pentaborate and lithium perborate; sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, hexaborate Sodium borate, sodium borate such as sodium octaborate; potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium borate such as potassium octaborate; calcium metaborate;
Calcium borate such as calcium diborate, tricalcium tetraborate, pentacalcium tetraborate, calcium hexaborate; magnesium metaborate, magnesium diborate;
Preferred are magnesium borates such as trimagnesium tetraborate, pentamagnesium tetraborate and magnesium hexaborate; or ammonium borates such as ammonium metaborate, ammonium tetraborate, ammonium pentaborate and ammonium octaborate. Can be Further, the boric acid ester includes an ester of boric acid and preferably an alkyl alcohol having 1 to 6 carbon atoms. Specific examples include monomethyl borate, dimethyl borate, trimethyl borate, monoethyl borate, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate ,
Tributyl borate and the like are preferred.

The neutral (normal salt) zinc sulfonate used for producing the overbased oil-soluble zinc sulfonate is, for example, sulfonating an alkyl aromatic compound having a weight average molecular weight of 100 to 1500, preferably 200 to 700. And a neutral salt of calcium or zinc of an alkyl aromatic sulfonic acid obtained by the above method. Examples of the alkyl aromatic sulfonic acid include petroleum sulfonic acid and synthetic sulfonic acid. As the petroleum sulfonic acid, a sulfonated alkyl aromatic compound of a lubricating oil fraction of a mineral oil, a so-called mahoganic acid, which is a by-product of white oil production, is generally used. Examples of the synthetic sulfonic acid include, for example, an alkylbenzene having a linear or branched alkyl group, which is obtained as a by-product from an alkylbenzene production plant used as a raw material of a detergent or obtained by alkylating a polyolefin to benzene. And sulfonated alkylnaphthalene such as dinonylnaphthalene. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, and usually, fuming sulfuric acid or sulfuric anhydride is used.

As the component (C), a commercial product diluted with a light lubricating base oil or the like can be usually used.

Although the zinc content of the component (C) is optional, the zinc content of the composition of the present invention is as follows in view of exhibiting an excellent synergistic effect on the anti-flaking performance.
0.5 to 30% by mass, especially 1 to 25% by mass is preferred.

The content of the component (C) is 0.05% by mass, preferably 0.1% by mass, and 10% by mass, preferably 5% by mass, based on the total amount of the grease composition.
It is. When the content ratio of the component (C) is less than 0.05% by mass, the synergistic effect with the component (B) on the anti-flaking performance is not sufficient. On the other hand, if it exceeds 10% by mass, the effect corresponding to the amount added to the flaking resistance cannot be obtained.

The grease composition of the present invention may contain a solid lubricant, an extreme pressure agent, an antioxidant, an oily agent, a rust inhibitor, if necessary, in order to further improve the performance, as long as its properties are not impaired. A viscosity index improver and the like can be contained.

Examples of the solid lubricant include graphite, graphite fluoride, boron nitride, polytetrafluoroethylene, molybdenum disulfide, antimony sulfide, and alkali (earth) metal borate. Examples of the extreme pressure agent include organic zinc compounds such as zinc dialkyldithiophosphate, zinc diaryldithiophosphate and zinc dialkyldithiocarbamate; organic molybdenum compounds such as molybdenum dialkyldithiophosphate, molybdenum diaryldithiophosphate and molybdenum dialkyldithiocarbamate; thiocarbamine Compounds: phosphates, phosphites and the like. Examples of the antioxidant include phenolic compounds such as 2,6-di-t-butylphenol and 2,6-di-t-butyl-p-cresol; dialkyldiphenylamine, phenyl-α-naphthylamine, p-alkylphenyl Amine compounds such as -α-naphthylamine; sulfur compounds; phenothiazine compounds and the like. Examples of the oil agent include amines such as laurylamine, myristylamine, palmitylamine, stearylamine, and oleylamine; higher alcohols such as lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and oleyl alcohol; Myristic acid, palmitic acid, stearic acid,
Higher fatty acids such as oleic acid; fatty acid esters such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate, and methyl oleate; lauramide, myristylamide, palmitylamide, stearylamide, oleylamide, etc. Amides; oils and fats. Examples of the rust inhibitor include metal soaps; polyhydric alcohol partial esters such as sorbitan fatty acid esters; amines; phosphoric acid; phosphates and the like. Examples of the viscosity index improver include polymethacrylate, polyisobutylene, and polystyrene.

To prepare the grease composition of the present invention,
For example, it can be obtained by mixing and stirring the above components (A) to (C) and, if necessary, other additives with a lubricating base oil and passing the mixture through a roll mill or the like. Further, the raw material component of the thickener of the component (A) is added to the lubricating base oil in advance, melted, and stirred and mixed to prepare the component (A), and then the components (B) and (C) Further, if necessary, other additives can be mixed and stirred, and the mixture can be passed through a roll mill or the like to produce the composition.

[0033]

The grease composition of the present invention is excellent in flaking resistance, seizure resistance, low abrasion resistance, etc., and thus is useful as a grease for constant velocity gears, transmission gears, steelmaking equipment, etc. In particular, it is useful for fixed joints such as bar field joints, Zeppa joints, and undercut free joints; and for constant velocity joints such as slide joints such as double offset joints, tripod joints, and cross groove joints. Can be used for grease.

[0034]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Examples 1-4 and Comparative Examples 1-6 As a lubricating base oil, the kinematic viscosity at 100 ° C. was 15 mm ² /
Using the solvent-refined paraffinic mineral oil of s, diphenylmethane-4,4′-diisocyanate in the amount shown in Table 1 was heated and dissolved in this base oil. Subsequently, a solution prepared by heating and dissolving the amines and alcohols shown in Table 1 in the same base oil was added to form a gel component (A). The composition of the component (A) in each of the generated examples is shown by the following structural formula.

[0035]

Embedded image

Next, the formed gel component (A) is
Various additives shown in Table 1 were added, stirred, and then passed through a roll mill to prepare each grease composition. In Comparative Example 1, instead of the component (A), lithium 12-hydroxystearate was dissolved in a lubricating base oil, and various additives shown in Table 1 were added. After stirring, the mixture was passed through a roll mill to obtain a grease composition. Was prepared.

Each of the obtained grease compositions was subjected to the following bench durability test. Table 1 shows the results. <Table endurance test> A commercially available # 87 size bar-field type joint is used under the condition that the mode in which the rotation speed, torque, and operating angle are changed is one cycle in consideration of the running pattern of the automobile, and the life of the joint is long. The number of cycles leading to was evaluated.

As is clear from the results of the bench durability test shown in Table 1, the grease composition of the present invention was obtained by using the grease composition of Comparative Example 1 using a compound other than the component (A) as a thickener, (B) It can be seen that the life of the constant velocity joint can be significantly extended as compared with the grease composition of Comparative Example 2 which does not contain the component and the grease composition of Comparative Example 5 which uses neutral zinc sulfonate instead of the component (C). Further, in the case of the grease composition of Comparative Example 6, which did not contain the components (B) and (C), seizure occurred at the start of the bench durability test, and the test could not be continued.

[0039]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 135: 28 159: 24) C10N 10:04 30:00 30:06 40:04 50:10

Claims (1)

[Claims] Claims 1. A lubricating base oil based on the total amount of a composition
(A) 2 to 30% by mass of a urea-based thickener, (B) 0.1 to 20% by mass of a sulfur-based extreme pressure agent, and (C) a total base number of 1
A grease composition containing 0.05 to 10% by mass of an overbased zinc sulfonate of 00 to 500 mgKOH / g.