JP4865380B2 - Grease composition - Google Patents

Description

  The present invention relates to a grease composition used for lubricating a ceramic sliding member such as silicon nitride and a metallic sliding member.

  Ceramics have excellent wear resistance, low friction, high elasticity, heat resistance, etc., so they tend to be widely used as sliding members that contribute to weight reduction and long life in automobiles and transportation machinery. It is in. In particular, it is expected to be used in places with severe sliding conditions such as high temperature and high load by taking advantage of the properties of heat resistance and high elasticity. With increasing interest in environmental issues in recent years, reducing friction at the sliding part leads to energy savings and, in turn, to reducing carbon dioxide emissions, so the use of ceramic parts is expected to increase in the future. Examples of specific parts to which the ceramic member is applied include a constant velocity joint, a rolling bearing, and the like.

Conventionally, there have been many reports on greases used for lubricating metal sliding members. In Patent Documents 1 and 2, etc., a grease or a grease-like substance used for lubrication between a metal member and a resin sliding member or between resin sliding members is proposed. Liquid lubricating oils have been proposed for use in lubrication between sliding members and metal sliding members.
However, there is no report that lubricates the ceramic sliding member and the metal sliding member with grease. Grease suitable for lubrication between metal sliding members does not always exhibit a sufficient friction reducing effect in lubrication between the ceramic sliding member and the metal sliding member.
JP 2003-20492 A Japanese Patent Application No. 2004-276017 JP 2000-265190 A

  An object of the present invention is to provide a grease composition for a ceramic-metal sliding member that can effectively reduce friction between the ceramic sliding member and the metal sliding member.

As a result of diligent research to solve the above-mentioned problems, the present inventors have used a grease composition containing a thickener and a solid molybdenum compound as a lubricant base oil, thereby providing a ceramic sliding member and It has been found that the friction with the metal sliding member can be greatly reduced, and the present invention has been completed.
That is, according to the present invention, the grease composition is used for lubrication of a ceramic sliding member and a metallic sliding member, and has a lubricating base oil of 60 mass consisting of mineral oil or polyolefin oil. % To 95% by mass , a urea-based or soap-based thickener 3% to 35% by mass, and 0.5 to 40% by mass of a solid molybdenum compound for a ceramic-metal sliding member. A grease composition (hereinafter sometimes abbreviated as the composition of the present invention) is provided.

The composition of the present invention applies a grease containing a lubricating base oil, a thickener, and a solid molybdenum compound between a ceramic sliding member and a metal sliding member. The friction between the ceramic-metal sliding member which is a location can be reduced sufficiently.
Therefore, the composition of the present invention is useful as a lubricant for constant velocity joints, rolling bearings, and the like, which include a ceramic sliding member and a metal sliding member.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The lubricating base oil used in the composition of the present invention comprises a mineral oil or a polyolefin oil.
As mineral oil, the mineral oil obtained by the method normally performed by the lubricating oil manufacturing process of petroleum refinery industry can be used. For example, lubricating oil fractions obtained by atmospheric and vacuum distillation of crude oil can be desolvated, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, clay treatment, etc. Ru can be given one or mineral oil, such as two or more paraffinic or naphthenic obtained by appropriate combination of refining processes.

As the polyolefin oil, any oil can be used, and among them, those obtained by polymerizing one or more olefins having 2 to 12 carbon atoms are preferable. Further, one obtained by polymerizing one or more of ethylene, propylene, 1-butene, 2-butene, isobutene, or a linear terminal olefin having 5 to 12 carbon atoms (hereinafter referred to as α-olefin) is more preferable. preferable.
Among these, a copolymer of ethylene and propylene; a copolymer of ethylene and an α-olefin having 5 to 12 carbon atoms; a polybutene, polyisobutene, or a polymer of α-olefin having 5 to 12 carbon atoms is preferable, A copolymer of ethylene and an α-olefin having 5 to 12 carbon atoms and an α-olefin polymer having 5 to 12 carbon atoms are more preferable.
The copolymer of ethylene and an α-olefin having 5 to 12 carbon atoms refers to a copolymer obtained by polymerizing ethylene and one or more α-olefins having 5 to 12 carbon atoms. The polymer of 12 α-olefin refers to a homopolymer obtained by polymerizing one kind of α-olefin having 5 to 12 carbon atoms, or a copolymer obtained by polymerizing two or more kinds.
The number average molecular weight of the copolymer of ethylene and an α-olefin having 5 to 12 carbon atoms and the polymer of an α-olefin having 5 to 12 carbon atoms is preferably 500 to 4000.

Among the above-mentioned base oils, Po Li-olefin oil, particularly preferably from α- olefin polymer having 5 to 12 carbon atoms in yet in the polyolefin oil. Moreover, a base oil may be used individually by 1 type, and may mix and use 2 or more types of different lubricating oil base oil.

Kinematic viscosity at 100 ° C. of the lubricating base oil in order to keep an appropriate viscosity grease composition, preferably 1~2000mm ² / s, more preferably ^{3~1000mm 2 / s, 5~500mm 2 /} s is Further preferred.
The content of the lubricating base oil is 60 % by mass or more, more preferably 70% by mass or more, based on the entire composition. If the content of the lubricating base oil is less than 60% by mass, it may be difficult to obtain good lubricity. The content of the lubricating base oil in the total composition basis, 9 5 mass%, more preferably at most 90 mass%. When the content of the lubricating base oil exceeds 95% by mass, it may be difficult to make the grease composition sufficiently greasy.

Thickening agents for use in the compositions of the present invention, a metal soap, a soap thickener or urethane A thickener such as complex metal soap. Since there is little possibility of damaging the ceramic member, soap-based thickeners and urea-based thickeners are preferably used.
Examples of the soap-based thickener include sodium soap, calcium soap, aluminum soap, and lithium soap. Among these, lithium soap is preferable from the viewpoint of water resistance and thermal stability. Examples of lithium soap include lithium stearate and lithium-12-hydroxystearate.
Examples of the urea thickener include a urea compound, a urea / urethane compound, a urethane compound, or a mixture thereof.

Examples of urea compounds, urea / urethane compounds and urethane compounds include diurea compounds, triurea compounds, tetraurea compounds, polyurea compounds (excluding diurea compounds, triurea compounds and tetraurea compounds), urea / urethane compounds, diurethane compounds or mixtures thereof. Etc. Preferably, a diurea compound, a urea / urethane compound, a diurethane compound or a mixture thereof is used. More specifically, for example, the compound represented by the formula (1) alone or a mixed system thereof is preferable.

^{A-CONH-R 1 -NHCO-} B (1)
In formula (1), R ¹ represents a divalent organic group, preferably a divalent hydrocarbon group. Examples of the divalent hydrocarbon group include a linear or branched alkylene group, a linear or branched alkenylene group, a cycloalkylene group, an arylene group, an alkylarylene group, and an arylalkylene group. . The carbon number of the divalent organic group represented by R ¹ is preferably 6 to 20, and more preferably 6 to 15.
Preferable examples of the divalent organic group represented by R ¹ include an ethylene group, a 2,2-dimethyl-4-methylhexylene group, and groups represented by formulas (2) to (11). Of these, groups represented by formulas (3) and (5) are preferred.

In formula (1), A and B may be the same or different and each represents a group represented by —NHR ² , —NR ³ R ⁴ or OR ⁵ . Here, R ^{2 to} R ⁵ may be the same or different and each is a monovalent organic group, and preferably represents a monovalent hydrocarbon group having 6 to 20 carbon atoms.
Examples of the monovalent hydrocarbon group having 6 to 20 carbon atoms represented by R ^{2 to} R ⁵ include a linear or branched alkyl group, a linear or branched alkenyl group, a cycloalkyl group, Examples thereof include an alkylcycloalkyl group, an aryl group, an alkaryl group, an aralkyl group, and the like. More specifically, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl Linear or branched alkyl groups such as hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl Straight chain or branched alkenyl group such as eicocenyl group; cyclohexyl group; methylcyclohexyl group, dimethylcyclohexyl group, ethylcyclohexyl group, diethylcyclohexyl group, propylcyclohexyl group, isopropylcyclohexane Xyl group, 1-methyl-3-propylcyclohexyl group, butylcyclohexyl group, amylcyclohexyl group, amylmethylcyclohexyl group, hexylcyclohexyl group, heptylcyclohexyl group, octylcyclohexyl group, nonylcyclohexyl group, decylcyclohexyl group, undecylcyclohexyl group , Dodecylcyclohexyl group, tridecylcyclohexyl group, alkyldecyl group such as tetradecylcyclohexyl group; aryl group such as phenyl group, naphthyl group; toluyl group, ethylphenyl group, xylyl group, propylphenyl group, cumenyl group, methylnaphthyl group Alkaryl groups such as ethyl naphthyl group, dimethyl naphthyl group and propyl naphthyl group; aralkyl groups such as benzyl group, methylbenzyl group and ethylbenzyl group . Among these, from the viewpoint of heat resistance and acoustic preventing properties, an alkyl group, a cycloalkyl group, alkylcycloalkyl group, an aryl group and alkaryl group.

The compound represented by the formula (1) is, for example, a diisocyanate represented by OCN—R ¹ —NCO, a compound represented by R ² NH ₂ , R ³ R ⁴ NH or R ⁵ OH, or a mixture thereof. Can be obtained by reacting in a base oil at 10 to 200 ° C. In addition, R < ¹ > -R < ⁵ > in the formula showing a raw material compound is synonymous with R < ¹ > -R < ⁵ > which concerns on the compound represented by Formula (1), respectively.

The content of the thickener is 3 % by mass or more, more preferably 4% by mass or more, and further preferably 5% by mass or more, based on the total amount of the composition. If the content of the thickener is less than 3% by mass, the effect of adding the thickener is insufficient, and it may be difficult to make the grease composition sufficiently greasy. The content of thickener, based on the total amount of the composition, 35 wt% or less, 20 wt% and more preferably less, more preferably 10 mass% or less. If the content of the thickener exceeds 35% by mass, the grease composition may become excessively hard and it may be difficult to obtain sufficient lubrication performance.

The composition of the present invention contains a solid molybdenum compound as an essential component in addition to the lubricating base oil and the thickener. Examples of the solid molybdenum compound include solid molybdenum dithiocarbamate and molybdenum disulfide. Here, the solid molybdenum dithiocarbamate refers to molybdenum dithiocarbamate contained in the solid component when the grease composition is separated into a liquid component and a solid component.
The solid component in the grease composition can be defined as that obtained by the following separation operation. That is, 5 g of the grease composition is added to 50 g of n-hexane and stirred. The mixture is centrifuged at 30000 G for about 10 minutes using a centrifuge. While the liquid separated by this operation is transferred to another container, 50 g of n-hexane is added to the residue, and the centrifugation operation is performed again under the same conditions as described above. While the separated liquid is mixed with the previously separated liquid, 50 g of n-hexane is added to the residue, and the third centrifugation operation is performed under the same conditions as described above. The remainder of the third operation is defined as a solid component.
Solid molybdenum dithiocarbamate is represented by the following structural formula (12).

In formula (12), R ^{6 to} R ⁹ each represent a hydrocarbon group having 1 or more carbon atoms, and may be the same or different. X is O or S. Examples of R ^{6 to} R ⁹ include an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkaryl group, and an aralkyl group.

  Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. Group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group and the like. Examples of the cycloalkyl group include a cyclopentyl group, an ethylcyclopentyl group, a cyclohexyl group. Etc.

  Examples of the alkylcycloalkyl group include a methylcyclopentyl group, an ethylcyclopentyl group, a dimethylcyclopentyl group, a propylcyclopentyl group, a methylethylcyclopentyl group, a trimethylcyclopentyl group, a butylcyclopentyl group, a methylpropylcyclopentyl group, a trimethylcyclopentyl group, and a butylcyclopentyl group. , Methylpropyl cyclopentyl group, diethyl cyclopentyl group, dimethyl ethyl cyclopentyl group, methyl cyclohexyl group, ethyl cyclohexyl group, dimethyl cyclohexyl group, propyl cyclohexyl group, methyl ethyl cyclohexyl group, trimethyl cyclohexyl group, butyl cyclohexyl group, methyl propyl cyclohexyl group, methyl Cycloheptyl group, ethylcycloheptyl group, dimethyl Examples include cycloheptyl, propylcycloheptyl, methylethylcycloheptyl, trimethylcycloheptyl, butylcycloheptyl, methylpropylcycloheptyl, diethylcycloheptyl, dimethylethylcycloheptyl, etc. Examples thereof include a phenyl group and a naphthyl group.

Examples of the alkaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, methylethylphenyl group, trimethylphenyl group, butylphenyl group, methylpropylphenyl group, diethylphenyl group, dimethylethylphenyl group, and pentyl. Phenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, tridecylphenyl group, tetradecylphenyl group, pentadecylphenyl group, hexadecylphenyl group Group, heptadecylphenyl group, octadecylphenyl group and the like, and examples of the aralkyl group include benzyl group, phenethyl group, phenylpropyl group, phenylbutyl group and the like.
Of the above organic groups, those having branched isomers or substituted isomers are also included in R ^{6 to} R ⁹ .

  As molybdenum disulfide, those widely used as solid lubricants can be used. As the lubrication mechanism, it is known that it has a layered lattice structure, easily shears into a thin layer by a sliding motion, and reduces the frictional resistance.

The content of the solid molybdenum compound is 0.5 to 40 % by mass based on the total amount of the composition . If it is less than 0.1% by mass, the improvement in wear resistance and galling resistance may be insufficient. Moreover, even if more than 50 wt%, since the effect of improving wear resistance and galling resistance is almost saturated, Ru uneconomical der.

In the composition of this invention, extreme pressure agents, such as a sulfur type compound, a phosphorus type compound, or an organic zinc compound, can be added individually or in combination of 2 or more types.
Examples of the sulfur-based extreme pressure agent that can be used in the present invention include dihydrocarbyl polysulfide, sulfide ester, sulfide mineral oil, thiazole compound, and thiadiazole compound. Of these, dihydrocarbyl polysulfide and sulfurized ester are preferable from the viewpoint of wear resistance.

Dihydrocarbyl polysulfide is a sulfur-based compound generally called polysulfide or sulfurized olefin, and any sulfur content can be used. However, from the viewpoint of wear resistance, the sulfur content is usually 10 to 55% by mass, preferably Is preferably 20 to 50% by mass. Examples of the dihydrocarbyl polysulfide include a compound represented by the formula (13).
R ¹⁰ -Sx-R ¹¹ (13)
In the formula (13), R ¹⁰ and R ¹¹ may be the same or different, and are each a linear or branched alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 carbon atoms. Represents an alkaryl group having 20 to 20 carbon atoms or an aralkyl group having 6 to 20 carbon atoms, and x represents an integer of 2 to 6, preferably 2 to 5.

Examples of the alkyl group represented by R ¹⁰ and R ¹¹ include n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl. Groups, octyl groups, nonyl groups, decyl groups, undecyl groups, dodecyl groups, tridecyl groups, tetradecyl groups, pentadecyl groups, hexadecyl groups, heptadecyl groups, octadecyl groups, nonadecyl groups, icosyl groups. After the pentyl group, it may be linear or branched.
Examples of the aryl group represented by R ¹⁰ and R ¹¹ include a phenyl group and a naphthyl group.

Examples of the alkaryl group represented by R ¹⁰ and R ¹¹ include tolyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, and nonylphenyl. Group, decylphenyl group, undecylphenyl group, dodecylphenyl group, xylyl group, ethylmethylphenyl group, diethylphenyl group, dipropylphenyl group, dibutylphenyl group, methylnaphthyl group, ethylnaphthyl group, propylnaphthyl group, butylnaphthyl Group, dimethylnaphthyl group, ethylmethylnaphthyl group, diethylnaphthyl group, dipropylnaphthyl group, dibutylnaphthyl group, and all of these structural isomers. Further, the alkyl group of these alkaryl groups may be either straight chain or branched.
Examples of the aralkyl group represented by R ¹⁰ and R ¹¹ include a benzyl group, a phenylethyl group, and a phenylpropyl group, and include all of these structural isomers.

R ¹⁰ and R ¹¹ are each an alkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 8 carbon atoms, an alkaryl group having 7 to 8 carbon atoms, or a carbon number derived from propylene, 1-butene or isobutylene. A 7 to 8 aralkyl group is preferred.
Specifically, preferable alkyl groups include an isopropyl group, a branched hexyl group derived from a propylene dimer, a branched nonyl group derived from a propylene trimer, and a propylene tetramer. Branched dodecyl group, branched pentadecyl group derived from propylene pentamer, branched octadecyl group derived from propylene hexamer, sec-butyl group, tert-butyl group, 1-butene dimer Branched octyl group derived from 1, branched octyl group derived from isobutylene dimer, branched dodecyl group derived from 1-butene trimer, branched derived from isobutylene trimer A branched dodecyl group, a branched hexadecyl group derived from a 1-butene tetramer, and a branched hexadecyl group derived from an isobutylene tetramer. All structural isomers.
A preferable aryl group includes a phenyl group.
Preferred alkaryl groups include tolyl groups, ethylphenyl groups, and xylyl groups, and include all of these structural isomers.
Preferable aralkyl groups include benzyl group and phenethyl group, and all of these structural isomers are included.

R ¹⁰ and R ¹¹ are each more preferably a branched alkyl group having 3 to 18 carbon atoms derived from ethylene or propylene, and is preferably derived from ethylene or propylene, because they are more excellent in wear resistance. Particularly preferred is a branched alkyl group having 6 to 15 carbon atoms.

Examples of sulfur esters include animal and vegetable fats and oils such as beef tallow, pork tallow, fish fat, rapeseed oil and soybean oil; unsaturated fatty acids such as oleic acid, linoleic acid or fatty acids extracted from the above-mentioned animal and vegetable fats and oils, and various alcohols. Unsaturated fatty acid ester obtained by making it react; and those obtained by carrying out the sulfidation of these mixtures etc. by arbitrary methods are mentioned.
As the sulfurized ester, those having an arbitrary sulfur content can be used, but from the viewpoint of wear resistance, it is usually preferable to use those having a sulfur content of 2 to 40% by mass, preferably 5 to 35% by mass.

Sulfided mineral oil refers to one obtained by dissolving elemental sulfur in mineral oil. As the mineral oil, the mineral oil described in the above-mentioned base oil can be used.
The elemental sulfur may be in any form such as a lump, powder or molten liquid, but the powder or molten liquid is preferred because it can be efficiently dissolved in mineral oil. When using molten liquid elemental sulfur, the liquids are mixed together, so there is an advantage that the melting operation can be performed in a very short time, but it is handled above the melting point of elemental sulfur. In addition, it is not always easy to handle because it requires a special device such as a heating facility or is handled in a high-temperature atmosphere and is dangerous. On the other hand, powdery simple sulfur is particularly preferable because it is inexpensive and easy to handle and has a sufficiently short dissolution time. Moreover, although there is no restriction | limiting in particular in sulfur content in sulfide mineral oil, Preferably it is 0.05-1.0 mass% normally on the basis of the total amount of sulfide mineral oil, More preferably, it is 0.1-0.5 mass%. .

As the thiazole compound, compounds represented by formulas (14) and (15) are preferable, and in particular, a benzothiazole compound represented by formula (15) is preferably used.

In formulas (14) and (15), R ¹² and R ¹³ each represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms or an amino group, preferably a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms, A hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms is more preferable. R ¹⁴ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a hydrocarbon group having 1 to 2 carbon atoms. d and e are each an integer of 0 to 3, preferably an integer of 0 to 2.
Examples of such benzothiazole compounds include benzothiazole, 2-mercaptobenzothiazole, 2- (hexyldithio) benzothiazole, 2- (octyldithio) benzothiazole, 2- (decyldithio) benzothiazole, and 2- (dodecyl). Dithio) benzothiazole, 2- (N, N-diethyldithiocarbamyl) benzothiazole.

  Examples of the thiadiazole compound include a 1,3,4-thiadiazole compound represented by the formula (16), a 1,2,4-thiadiazole compound represented by the formula (17), and a formula (18). A 1,4,5-thiadiazole compound is preferred.

In formulas (16) to (18), R ^{15 to} R ²⁰ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and each represents a hydrogen atom or a carbon atom having 1 to 18 carbon atoms. Hydrogen is preferable, and a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms is more preferable. f to k may be the same or different and each represents an integer of 0 to 3, and an integer of 0 to 2 is preferable.
Examples of such thiadiazole compounds include 2,5-bis (n-hexyldithio) -1,3,4-thiadiazole, 2,5-bis (n-octyldithio) -1,3,4-thiadiazole, 2,5-bis (n-nonyldithio) -1,3,4-thiadiazole, 2,5-bis (1,1,3,3-tetramethylbutyldithio) -1,3,4-thiadiazole, 3,5 -Bis (n-hexyldithio) -1,2,4-thiadiazole, 3,5-bis (n-octyldithio) -1,2,4-thiadiazole, 3,5-bis (n-nonyldithio) -1, 2,4-thiadiazole, 3,5-bis (1,1,3,3-tetramethylbutyldithio) -1,2,4-thiadiazole, 4,5-bis (n-hexyldithio) -1,2, 3-thiadiazole, 4,5-bis (n-octyldi Thio) -1,2,3-thiadiazole, 4,5-bis (n-nonyldithio) -1,2,3-thiadiazole, 4,5-bis (1,1,3,3-tetramethylbutyldithio)- 1,2,3-thiadiazole is mentioned.

  In the composition of the present invention, the content of the sulfur-based extreme pressure agent is not particularly limited, but is preferably 0.05 to 10% by mass, more preferably 0.1 to 7% by mass based on the total amount of the composition. %, More preferably 0.2 to 5% by mass.

Examples of the phosphorus-based extreme pressure agent that can be contained in the composition of the present invention include phosphate esters, acidic phosphate esters, phosphite esters, phosphorothionates, molybdenum phosphates, molybdenum thiophosphates, and molybdenum dithiophosphates. It can be used alone or as a mixture of two or more.
Among the phosphorous extreme pressure agents, phosphoric acid ester, acidic phosphoric acid ester and phosphorous acid ester are phosphoric acid or phosphoric acid and alkanol, an ester of polyether type alcohol or a derivative thereof.

  Examples of phosphate esters include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl phosphate, tritetradecyl phosphate. Decyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate Is mentioned.

  Examples of the acidic phosphate ester include monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate, Monododecyl acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid diphosphate Acid phosphate, dihex Ruacid phosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl phosphate, dipentadecyl phosphate Examples include dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate, and dioleyl acid phosphate.

  Examples of phosphites include dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, Dioleyl phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triun Examples include decyl phosphite, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, and tricresyl phosphite.

Examples of the phosphorothioate include a compound represented by the formula (19).

In the formula, R ^{21 to} R ²³ may be the same or different and each represents a hydrocarbon group having 1 to 24 carbon atoms.
Examples of the hydrocarbon group having 1 to 24 carbon atoms represented by R ^{21 to} R ²³ include an alkyl group, a cycloalkyl group, an alkenyl group, an alkylcycloalkyl group, an aryl group, an alkaryl group, and an aralkyl group. An alkyl group, an aryl group, and an alkaryl group are preferable, and an alkyl group having 4 to 18 carbon atoms, an alkaryl group having 7 to 24 carbon atoms, and a phenyl group are more preferable.
Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. And alkyl groups such as a hexadecyl group, a heptadecyl group, and an octadecyl group, which may be linear or branched.

As a cycloalkyl group, C5-C7 cycloalkyl groups, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, are mentioned, for example.
Examples of the alkylcycloalkyl group include a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, a dimethylcyclopentyl group, and the like. Examples thereof include alkylcycloalkyl groups having 6 to 11 carbon atoms such as heptyl group, methylethylcycloheptyl group, and diethylcycloheptyl group, and the substitution position of the alkyl group to the cycloalkyl group is arbitrary.
Examples of alkenyl groups include butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl Groups, which may be linear or branched, and the position of the double bond is arbitrary.

Examples of the aryl group include a phenyl group and a naphthyl group.
Examples of the alkaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, Examples thereof include alkaryl groups having 7 to 18 carbon atoms such as undecylphenyl group and dodecylphenyl group. The alkyl group may be linear or branched, and the substitution position on the aryl group is arbitrary.
Examples of the aralkyl group include aralkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group. It may be branched.

  Examples of the phosphorothioate represented by the formula (19) include tributyl phosphorothioate, tripentyl phosphorothioate, trihexyl phosphorothionate, triheptyl phosphorothionate, and trioctyl phosphorothionate. , Trinonyl phosphorothioate, tridecyl phosphorothionate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl phosphorothioate Thionate, trihexadecyl phosphorothioate, triheptadecyl phosphorothionate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, tricresyl phosphorothionate, trixylate Nilphos Lothionate, Cresyl diphenyl phosphorothioate, Xylenyl diphenyl phosphorothioate, Tris (n-propylphenyl) phosphorothioate, Tris (isopropylphenyl) phosphorothionate, Tris (n-butylphenyl) phosphorothioate Examples include thionate, tris (isobutylphenyl) phosphorothionate, tris (s-butylphenyl) phosphorothionate, and tris (t-butylphenyl) phosphorothionate. In use, it can be used alone or as a mixture of two or more.

Molybdenum phosphate, molybdenum thiophosphate, and molybdenum dithiophosphate are represented by, for example, formula (20).

In formula (20), R is the same or different groups, and represents a hydrocarbon group having 1 or more carbon atoms. X is O or S.
Examples of R include an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkaryl group, and an aralkyl group.
Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. Group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, and the cycloalkyl group includes, for example, cyclopentyl group, ethylcyclopentyl group, cyclohexyl group, etc. Is mentioned.

  Examples of the alkylcycloalkyl group include a methylcyclopentyl group, an ethylcyclopentyl group, a dimethylcyclopentyl group, a propylcyclopentyl group, a methylethylcyclopentyl group, a trimethylcyclopentyl group, a butylcyclopentyl group, a methylpropylcyclopentyl group, a trimethylcyclopentyl group, and a butylcyclopentyl group. , Methylpropyl cyclopentyl group, diethyl cyclopentyl group, dimethyl ethyl cyclopentyl group, methyl cyclohexyl group, ethyl cyclohexyl group, dimethyl cyclohexyl group, propyl cyclohexyl group, methyl ethyl cyclohexyl group, trimethyl cyclohexyl group, butyl cyclohexyl group, methyl propyl cyclohexyl group, methyl Cycloheptyl group, ethylcycloheptyl group, dimethyl Examples include cycloheptyl, propylcycloheptyl, methylethylcycloheptyl, trimethylcycloheptyl, butylcycloheptyl, methylpropylcycloheptyl, diethylcycloheptyl, dimethylethylcycloheptyl, etc. Examples thereof include a phenyl group and a naphthyl group.

Examples of the alkaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, methylethylphenyl group, trimethylphenyl group, butylphenyl group, methylpropylphenyl group, diethylphenyl group, dimethylethylphenyl group, and pentyl. Phenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, tridecylphenyl group, tetradecylphenyl group, pentadecylphenyl group, hexadecylphenyl group Group, heptadecylphenyl group, and octadecylphenyl group. Examples of the aralkyl group include benzyl group, phenethyl group, phenylpropyl group, and phenylbutyl group.
Among the above organic groups, those having branched isomers or substituted isomers are also included in R.

  In the composition of the present invention, the content in the case of containing a phosphorus extreme pressure agent is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.05 to 7% by mass based on the total amount of the composition. %, More preferably 0.1 to 5% by mass.

  Examples of the organic zinc compound that can be used in the composition of the present invention include a zinc dithiophosphate compound represented by the formula (21), a zinc dithiocarbamate compound represented by the formula (22), the formula (23) or ( The zinc salt of the phosphorus compound represented by 24) can be mentioned. Of these, zinc dithiophosphate compounds and zinc dithiocarbamate compounds are preferred from the viewpoint of wear resistance.

式(２１)中、Ｒ²⁴〜Ｒ²⁷は同一でも異なっていてもよく、それぞれ炭化水素基を表す。

In the formula (21), R ^{24 to} R ²⁷ may be the same or different and each represents a hydrocarbon group.

式(２２)中、Ｒ²⁸〜Ｒ³¹は同一でも異なっていてもよく、炭化水素基を表す。

In the formula (22), R ^{28 to} R ³¹ may be the same or different and each represents a hydrocarbon group.

式(２３)中、Ｙはそれぞれ酸素原子または硫黄原子を表し、３つのＹの少なくとも２つは酸素原子であり、好ましくは３つが酸素原子である。Ｒ³²〜Ｒ³⁴は同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜３０の炭化水素基を表すが、Ｒ³²〜Ｒ³⁴のうちの少なくとも１個は水素原子である。

In formula (23), Y represents an oxygen atom or a sulfur atom, respectively, and at least two of the three Y are oxygen atoms, preferably three are oxygen atoms. R ^{32 to} R ³⁴ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and at least one of R ^{32 to} R ³⁴ is a hydrogen atom.

式(２４)中、Ｙはそれぞれ酸素原子または硫黄原子を表し、４つのＹの少なくとも３つは酸素原子であり、好ましくは４つが酸素原子である。Ｒ³⁵〜Ｒ³⁷は同一でも異なっていてもよく、それぞれ水素原子または炭素数１〜３０の炭化水素基を表すが、Ｒ³⁵〜Ｒ³⁷のうちの少なくとも１個は水素原子である。

In the formula (24), Y represents an oxygen atom or a sulfur atom, respectively, and at least three of the four Y are oxygen atoms, preferably four are oxygen atoms. R ^{35 to} R ³⁷ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and at least one of R ^{35 to} R ³⁷ is a hydrogen atom.

In the formulas (21) and (22), examples of the hydrocarbon group of R ^{24 to} R ²⁷ or R ^{28 to} R ³¹ include, for example, an alkyl group having 1 to 24 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, carbon Examples thereof include an alkylcycloalkyl group having 6 to 11 carbon atoms, an aryl group having 6 to 18 carbon atoms, an alkaryl group having 7 to 24 carbon atoms, and an aralkyl group having 7 to 12 carbon atoms.
Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. Group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heneicosyl group, docosyl group, tricosyl group, tetracosyl group, and all these branched isomers.
Examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and the like.

Examples of the alkylcycloalkyl group include a methylcyclopentyl group, an ethylcyclopentyl group, a dimethylcyclopentyl group, a propylcyclopentyl group, a methylethylcyclopentyl group, a trimethylcyclopentyl group, a butylcyclopentyl group, a methylpropylcyclopentyl group, a diethylcyclopentyl group, and dimethylethylcyclopentyl. Group, methyl cyclohexyl group, ethyl cyclohexyl group, dimethyl cyclohexyl group, propyl cyclohexyl group, methyl ethyl cyclohexyl group, trimethyl cyclohexyl group, butyl cyclohexyl group, methyl propyl cyclohexyl group, diethyl cyclohexyl group, dimethyl ethyl cyclohexyl group, methyl cyclohexyl group, Ethylcycloheptyl group, dimethylcycloheptyl group, propylene Cycloheptyl group, methylethylcycloheptyl group, trimethylcycloheptyl group, butylcycloheptyl group, methylpropylcycloheptyl group, diethylcycloheptyl group, dimethylethylcycloheptyl group, and all these branched isomers, substituted Also included are isomers.
Examples of the aryl group include a phenyl group and a naphthyl group.

Examples of the alkaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, methylethylphenyl group, trimethylphenyl group, butylphenyl group, methylpropylphenyl group, diethylphenyl group, dimethylethylphenyl group, and pentyl. Phenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group, dodecylphenyl group, tridecylphenyl group, tetradecylphenyl group, pentadecylphenyl group, hexadecylphenyl group Group, heptadecylphenyl group, and octadecylphenyl group, and all these branched isomers and substituted isomers are also included.
Examples of the aralkyl group include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group, and all of these branched isomers.

In the formula (23) or (24), examples of the hydrocarbon group having 1 to 30 carbon atoms of R ^{32 to} R ³⁴ or R ^{35 to} R ³⁷ include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkylcycloalkyl group. , Aryl group, alkaryl group, and aralkyl group. Of these, an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 24 carbon atoms is preferable, an alkyl group having 3 to 18 carbon atoms is more preferable, and an alkyl group having 4 to 12 carbon atoms is particularly preferable.
In addition, R ^{32 to} R ³⁴ in the formula (23) or R ^{35 to} R ³⁷ in the formula (24) are each preferably 1 to 2 hydrocarbon groups, and preferably 2 are hydrocarbon groups. Further preferred.

Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. Group, hexadecyl group, heptadecyl group and octadecyl group, which may be linear or branched.
As a cycloalkyl group, C5-C7 cycloalkyl groups, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, are mentioned, for example.
Examples of the alkylcycloalkyl group include a methylcyclopentyl group, a dimethylcyclopentyl group, a methylethylcyclopentyl group, a diethylcyclopentyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, a methylethylcyclohexyl group, a diethylcyclohexyl group, a methylcycloheptyl group, a dimethylcyclopentyl group, and the like. Examples thereof include alkylcycloalkyl groups having 6 to 11 carbon atoms such as heptyl group, methylethylcycloheptyl group, and diethylcycloheptyl group, and the substitution position of the alkyl group to the cycloalkyl group is arbitrary.

Examples of alkenyl groups include butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl Groups, which may be linear or branched, and the position of the double bond is arbitrary.
Examples of the aryl group include a phenyl group and a naphthyl group.
Examples of the alkaryl group include tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group, heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, Examples thereof include alkaryl groups having 7 to 18 carbon atoms such as undecylphenyl group and dodecylphenyl group. The alkyl group may be linear or branched, and the substitution position on the aryl group is arbitrary.
Examples of the aralkyl group include aralkyl groups having 7 to 12 carbon atoms such as benzyl group, phenylethyl group, phenylpropyl group, phenylbutyl group, phenylpentyl group, and phenylhexyl group. It may be branched.

Examples of the phosphorus compound represented by the formula (23) include phosphorous acid and monothiophosphorous acid; phosphorous acid monoester and monothiophosphorous acid monoester having one hydrocarbon group having 1 to 30 carbon atoms. A phosphorous acid diester having two hydrocarbon groups having 1 to 30 carbon atoms, a monothiophosphorous acid diester; or a mixture thereof. Among these, phosphorous acid monoester and phosphorous acid diester are preferable, and phosphorous acid diester is more preferable.
Examples of the phosphorus compound represented by the formula (24) include phosphoric acid and monothiophosphoric acid; phosphoric acid monoester and monothiophosphoric acid monoester having one hydrocarbon group having 1 to 30 carbon atoms; And phosphoric acid diesters having two 30 hydrocarbon groups, monothiophosphoric acid diesters; or mixtures thereof. Among these, phosphoric acid monoester and phosphoric acid diester are preferable, and phosphoric acid diester is more preferable.

The structure of the zinc salt of the phosphorus compound represented by the formula (23) or (24) differs depending on the number of OH groups or SH groups of the phosphorus compound, and the structure is not limited at all. For example, when 1 mol of zinc oxide and 2 mol of phosphoric acid diester (one OH group) are reacted, a compound having a structure represented by formula (25) is considered to be obtained as a main component. Is also considered to exist. R in the formula represents a hydrocarbon group having 1 to 30 carbon atoms.

In addition, for example, when 1 mol of zinc oxide and 1 mol of phosphoric acid monoester (having two OH groups) are reacted, a compound having a structure represented by the formula (26) is considered to be obtained as a main component. It is thought that there are some molecules R in the formula represents a hydrocarbon group having 1 to 30 carbon atoms.

  In the composition of the present invention, the content when the organozinc compound is contained is not particularly limited, but is preferably 0.05 to 10% by mass, more preferably 0.1 to 7% by mass, based on the total amount of the composition. More preferably, it is 0.2-5 mass%.

In the composition of the present invention, a solid lubricant other than the solid molybdenum compound, a wax, an antioxidant, a carbonate-dispersed overbased fatty acid, and an organic acid salt, if necessary, as long as the properties are not impaired. , Oily agents, rust inhibitors, viscosity index improvers, and the like can be included.
Examples of the solid lubricant include graphite, graphite fluoride, polytetrafluoroethylene, boron nitride, melamine cyanurate, antimony sulfide, and alkali (earth) metal borate.
Examples of the wax include natural waxes, various mineral oils and synthetic waxes, and specifically include montan wax, carnauba wax, amide compounds of higher fatty acids, paraffin wax, microcrystalline wax, polyethylene wax, polyolefin wax. And ester wax.
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, and p-alkylphenyl. Examples include amine compounds such as -α-naphthylamine; sulfur compounds; phenothiazine compounds.

  Carbonate-dispersed overbased fatty acid salt is a fatty acid salt that is overbased with carbonate by dispersing carbonate in the fatty acid salt. Specifically, oleic acid, erucic acid, linoleic acid, etc. An inorganic salt such as calcium carbonate is dispersed in an alkali metal salt or an alkaline earth metal salt of a fatty acid. The base number of the carbonate-dispersed overbased fatty acid salt is usually 50 mgKOH / g or more, preferably 150 mgKOH / g or more, more preferably 250 mgKOH / g or more, because it is excellent in seizure resistance. Although there is no restriction | limiting in particular about an upper limit, Generally it is 600 mgKOH / g or less.

Examples of organic acid salts include sulfonates, phenates, salicylates, and the like, and alkali metals, alkaline earth metals, and amines are used as the corresponding cations, with calcium being particularly preferred. Organic acid salts include organic acids and alkali metal bases such as alkali metal oxides and hydroxides, alkaline earth metal bases such as alkaline earth metal oxides and hydroxides, or ammonia and alkyl. So-called neutral salts obtained by reacting amines such as amines and alkanolamines; heating neutral salts and excess alkali metal bases, alkaline earth metal bases or amines in the presence of water So-called basic salts obtained by reacting neutral salts with alkali metal bases, alkaline earth metal bases or amines in the presence of carbon dioxide. ) Salts; neutral salts reacted with alkali metal bases, alkaline earth metal bases or amines and boric acid compounds such as boric acid or boric anhydride, or carbonate persalts Sex are prepared by reacting a boric acid compound such as (overbased) salts of boric acid or boric acid anhydride, a so-called borate overbased (ultrabasic) salts, or mixtures thereof.
The base number of the organic acid salt is preferably 50 to 500 mgKOH / g, more preferably 100 to 450 mgKOH / g. When the base number of the organic acid salt is less than 50 mgKOH / g, the lubricity improvement effect due to the addition of the organic acid salt tends to be insufficient. On the other hand, the organic acid salt whose base number exceeds 500 mgKOH / g is usually Each is not preferable because it is very difficult to manufacture and difficult to obtain.

Examples of the oily 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; lauric acid and myristic acid , Higher fatty acids such as palmitic acid, stearic acid, oleic acid; fatty acid esters such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate; laurylamide, myristylamide, palmitylamide, stearylamide Amides such as oleylamide; oils and fats.
Examples of the rust inhibitor include metal soap; polyhydric alcohol partial ester such as sorbitan fatty acid ester; amine; phosphoric acid; phosphate.
Examples of the thickener include polymethacrylate, polyisobutylene, polystyrene and the like.

  To prepare the composition of the present invention, for example, a lubricant base oil is mixed with a thickener, a solid molybdenum compound, and other additives as necessary, and stirred, and then passed through a roll mill or the like. Obtainable. Also, after adding a thickener raw material component to the lubricating base oil in advance and melting and stirring and mixing, the thickener is prepared in the lubricating base oil, and then a solid molybdenum compound, and if necessary The other additives can be mixed and stirred and passed through a roll mill or the like.

Suitable ceramic members for using the composition of the present invention include, for example, silicon nitride, silicon carbide, tungsten carbide, titanium carbide, and aluminum oxide. Moreover, a metal member is not specifically limited.
The composition of the present invention can greatly reduce the friction between the ceramic sliding member and the metal sliding member, and is sufficient for the resin material disposed at or near the sliding portion. Have good compatibility. Such a resin is not particularly limited, and examples thereof include polyacetal, polyester, polyethylene, polypropylene, polyamide, polycarbonate, polyurethane, and composites thereof.
The composition of the present invention has high compatibility with rubber disposed near the sliding portion. Such rubber is not particularly limited, and examples thereof include nitrile, chloroprene, fluorine, ethylene-propylene, acrylic, and composites thereof.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
Examples 1-8, Comparative Examples 1 and 2
In accordance with the composition shown in Table 1, diphenylmethane-4,4′-diisocyanate as a thickener raw material is dissolved in a base oil by heating, and other thickener raw materials are added and reacted therein to form a gel. To the solid substance, molybdenum disulfide and / or molybdenum dithiocarbamate as a solid molybdenum compound and an additive were added and stirred to prepare a grease. The obtained grease was treated with a roll mill to a consistency of 300 ± 15.
As the base oil, a solvent-purified paraffinic mineral oil having a kinematic viscosity at 100 ° C. of 16.0 mm ² / s or a poly-α-olefin having a kinematic viscosity at 100 ° C. of 40.2 mm ² / s was used. Thickeners include urea-urethane, which is a reaction product of diphenylmethane-4,4′-diisocyanate, cyclohexylamine and octadecyl alcohol, or diphenylmethane-4,4′-diisocyanate, cyclohexylamine and p -A urea system which is a reaction product of toluidine was used.
In Table 1, polysulfide is an extreme pressure agent, di-t-butyl-p-cresol is an antioxidant, and overbased calcium sulfonate is an organic acid salt.

Using the obtained grease, the friction characteristic evaluation test between the ceramic sliding member and the metal sliding member shown below was performed.
Using a SRV friction tester, the test was conducted using a silicon nitride sphere having a diameter of 10 mm as the upper sliding member and a SUJ2 disk having a diameter of 24 mm and a thickness of 7.9 mm as the lower sliding member. The sliding conditions were a load of 300 N (50 N for 30 seconds after the start of the test), a temperature of 160 ° C., a horizontal movement speed of 30 mm / s, a friction coefficient after 300 seconds from the start of the test, and the disc test piece after the end of the test. The wear scar area was measured. The results are shown in Table 1.
From Table 1, in the grease of the example to which the solid molybdenum compound was added, the friction coefficient between the ceramic sliding member and the metal sliding member was significantly reduced, and the wear scar area was also small.

Claims (3)

A grease composition characterized by being used for lubrication of a ceramic sliding member and a metallic sliding member,
Lubricating oil base oil composed of mineral oil or polyolefin oil 60 mass% or more and 95 mass% or less ,
A urea-based or soap-based thickener 3% by mass to 35% by mass ;
A grease composition for a ceramic-metal sliding member containing 0.5 to 40% by mass of a solid molybdenum compound. The grease composition according to claim 1, wherein the thickener comprises a urea thickener. The grease composition according to claim 1 or 2, wherein the ceramic sliding member is a silicon nitride sliding member.