CN111004672A - Grease composition and rolling bearing - Google Patents

Grease composition and rolling bearing Download PDF

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Publication number
CN111004672A
CN111004672A CN201910909604.0A CN201910909604A CN111004672A CN 111004672 A CN111004672 A CN 111004672A CN 201910909604 A CN201910909604 A CN 201910909604A CN 111004672 A CN111004672 A CN 111004672A
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grease composition
thickener
base oil
grease
rolling bearing
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萩野侑里惠
津田武志
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JTEKT Corp
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JTEKT Corp
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M157/00—Lubricating compositions characterised by the additive being a mixture of two or more macromolecular compounds covered by more than one of the main groups C10M143/00 - C10M155/00, each of these compounds being essential
    • C10M157/10—Lubricating compositions characterised by the additive being a mixture of two or more macromolecular compounds covered by more than one of the main groups C10M143/00 - C10M155/00, each of these compounds being essential at least one of them being a compound containing atoms of elements not provided for in groups C10M157/02 - C10M157/08
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/06—Mixtures of thickeners and additives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/08—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing oxygen
    • C10M105/18—Ethers, e.g. epoxides
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M115/00—Lubricating compositions characterised by the thickener being a non-macromolecular organic compound other than a carboxylic acid or salt thereof
    • C10M115/08—Lubricating compositions characterised by the thickener being a non-macromolecular organic compound other than a carboxylic acid or salt thereof containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M155/00—Lubricating compositions characterised by the additive being a macromolecular compound containing atoms of elements not provided for in groups C10M143/00 - C10M153/00
    • C10M155/02—Monomer containing silicon
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/02—Mixtures of base-materials and thickeners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/66—Special parts or details in view of lubrication
    • F16C33/6603—Special parts or details in view of lubrication with grease as lubricant
    • F16C33/6633—Grease properties or compositions, e.g. rheological properties
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/04—Ethers; Acetals; Ortho-esters; Ortho-carbonates
    • C10M2207/0406—Ethers; Acetals; Ortho-esters; Ortho-carbonates used as base material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant compositions
    • C10M2215/10—Amides of carbonic or haloformic acids
    • C10M2215/102—Ureas; Semicarbazides; Allophanates
    • C10M2215/1026—Ureas; Semicarbazides; Allophanates used as thickening material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
    • C10M2217/04—Macromolecular compounds from nitrogen-containing monomers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • C10M2217/045—Polyureas; Polyurethanes
    • C10M2217/0456—Polyureas; Polyurethanes used as thickening agents
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
    • C10M2229/04—Siloxanes with specific structure
    • C10M2229/041—Siloxanes with specific structure containing aliphatic substituents
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
    • C10M2229/04—Siloxanes with specific structure
    • C10M2229/042—Siloxanes with specific structure containing aromatic substituents
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
    • C10M2229/04—Siloxanes with specific structure
    • C10M2229/046—Siloxanes with specific structure containing silicon-oxygen-carbon bonds
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2229/00—Organic macromolecular compounds containing atoms of elements not provided for in groups C10M2205/00, C10M2209/00, C10M2213/00, C10M2217/00, C10M2221/00 or C10M2225/00 as ingredients in lubricant compositions
    • C10M2229/04—Siloxanes with specific structure
    • C10M2229/047—Siloxanes with specific structure containing alkylene oxide groups
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/02—Viscosity; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/02—Pour-point; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/02—Bearings
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
    • C10N2050/10—Semi-solids; greasy

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  • General Chemical & Material Sciences (AREA)
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  • General Engineering & Computer Science (AREA)
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Abstract

The present invention relates to a grease composition and a rolling bearing. A grease composition (G) comprising a base oil, a thickener and an organomodified polysiloxane. The base oil is an alkyl diphenyl ether. The thickener is a urea thickener, and the grease composition (G) contains 10 to 30 mass% of the thickener based on the total amount of the base oil and the thickener. The grease composition (G) contains 0.2 to 10 mass% of the organomodified polysiloxane based on the total amount of the base oil and the thickener.

Description

Grease composition and rolling bearing
Technical Field
The present invention relates to a grease composition and a rolling bearing in which the grease composition is sealed.
Background
Bearings used in automotive electrical parts such as alternators, electromagnetic clutches for automotive air conditioners, intermediate pulleys, and electric fan motors, and automotive engine accessories, etc., are used in severe environments such as high temperature, high speed, high load, and high vibration. In rolling bearings used in such severe environments, early flaking associated with microstructural changes in steel sometimes occurs in the lock ring and the rolling elements during use of the bearing.
Greases have been reported which are intended to address the problem of premature flaking. For example, international patent publication No. WO 94/03565 and japanese unexamined patent application publication nos. 2004-108403 and 2012-233158 disclose greases containing urea thickeners and extreme pressure additives.
Disclosure of Invention
In recent years, rolling bearings have been used under more severe conditions, and early flaking is more likely to occur in rolling bearings. Such early spalling associated with microstructural changes in the steel is quite different from the initial spalling below the surface and is characterized by a white microstructure. Such early exfoliation is referred to as white structure exfoliation. The mechanism causing such peeling of the white structure is mainly an increase in internal stress due to sliding, high surface pressure, impact load, and the like. Further, a tribochemical reaction or the like occurs on a fresh surface exposed by friction between the inner and outer races and the rolling elements, so that hydrogen is generated by decomposition of water and grease. This hydrogen will permeate the bearing steel, further promoting the spalling of the white structure.
It has been proposed to suppress the occurrence of such white structure peeling by reducing friction and impact load. In the proposed method, friction is reduced by adding a specific extreme pressure additive, as described above, and impact load is reduced by increasing the thickness of a grease film on the surface of the rolling element. However, this method cannot reliably avoid the white structure from peeling off. A grease more suitable for avoiding such early flaking is therefore desired.
The invention provides a grease composition which can inhibit the occurrence of white structure peeling in a rolling bearing; and a rolling bearing.
The grease composition according to the first aspect of the invention comprises: base oil, thickener and organic modified polysiloxane. The base oil is an alkyl diphenyl ether. The thickener is a urea thickener, and the grease composition contains 10 to 30 mass% of the thickener, based on the total amount of the base oil and the thickener. The grease composition contains 0.2 to 10 mass% of an organomodified polysiloxane based on the total amount of base oil and thickener.
When used in a rolling bearing, the grease composition according to the first aspect of the invention can suppress the occurrence of flaking of white structure in the rolling bearing. The reason for this is as follows. The grease composed of the grease composition contains a predetermined amount of an organomodified polysiloxane. The grease thus has excellent wettability to steel. Therefore, when grease is used by sealing in a rolling bearing, the grease can easily enter between each rolling element and the rolling surfaces of the inner and outer races. The grease can therefore easily form a grease film on the rolling contact portions between the respective rolling elements and the inner and outer races and can continuously contribute to lubrication of the rolling contact portions without causing an oil film shortage. The rolling bearing in which the grease is sealed can therefore reduce the increase in internal stress in the rolling contact portion. Further, since the grease continuously contributes to lubrication, the grease can suppress the formation of a new surface due to wear, and thus can suppress the generation of hydrogen by a tribochemical reaction occurring on the exposed new surface. The grease is thus capable of preventing an increase in internal stress in the rolling contact portion, suppressing the generation of hydrogen, and suppressing the occurrence of white structure peeling.
In the grease composition according to the first aspect of the invention, the organomodified polysiloxane may be at least one selected from an aralkyl-modified polymethylalkylsiloxane and a polyether-modified polydimethylsiloxane.
When used in a rolling bearing used in a severe environment, the grease composition according to the first aspect of the invention can suppress the occurrence of flaking of white structure in the rolling bearing.
The rolling bearing according to the second aspect of the invention comprises a grease composition sealed in the rolling bearing. The grease composition contains a base oil, a thickener and an organic modified polysiloxane. The base oil is an alkyl diphenyl ether. The thickener is a urea thickener, and the grease composition contains 10 to 30 mass% of the thickener, based on the total amount of the base oil and the thickener. The grease composition contains 0.2 to 10 mass% of an organomodified polysiloxane based on the total amount of base oil and thickener.
In the rolling bearing according to the second aspect of the invention, the organic modified polysiloxane may be at least one selected from an aralkyl modified polymethylalkylsiloxane and a polyether modified polydimethylsiloxane.
The rolling bearing according to the second aspect of the invention can suppress the occurrence of the peeling of the white structure.
Drawings
Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described hereinafter with reference to the accompanying drawings, in which like reference numerals refer to like elements, and in which:
FIG. 1 is a cross-sectional view of a ball bearing according to one embodiment of the present invention; and is
Fig. 2 is a graph showing the evaluation results of the cumulative hydrogen generation amounts of the grease compositions prepared in the examples and comparative examples.
Detailed Description
Embodiments of the present invention will be described with reference to the accompanying drawings. The rolling bearing according to the embodiment is a ball bearing in which the grease composition according to the embodiment of the present invention is sealed. Fig. 1 is a sectional view of a ball bearing according to an embodiment of the present invention. The ball bearing 1 includes an inner race 2, an outer race 3, balls 4 as a plurality of rolling elements, and an annular cage 5. The outer race 3 is disposed radially outward of the inner race 2. The balls 4 are arranged between the inner ring 2 and the outer ring 3. The retainer 5 retains the ball 4 therein. The seal members 6 are provided on one side and the other side in the axial direction of the ball bearing 1. Grease G composed of the grease composition according to the embodiment of the present invention is sealed in the annular region 7 between the inner ring 2 and the outer ring 3.
The inner race 2 has an inner raceway surface 21 along its outer periphery on which the balls 4 roll, and the outer race 3 has an outer raceway surface 31 along its inner periphery on which the balls 4 roll. The plurality of balls 4 are interposed between the inner raceway surface 21 and the outer raceway surface 31 and roll on the inner raceway surface 21 and the outer raceway surface 31. The grease G sealed in the region 7 is also present in the contact portion between each ball 4 and the inner raceway surface 21 of the inner ring 2 and the contact portion between each ball 4 and the outer raceway surface 31 of the outer ring 3. The grease G is sealed in the ball bearing 1 to occupy 20% to 40% of the volume of the space remaining in the volume of the space surrounded by the inner ring 2, the outer ring 3, and the seal 6 except for the volume of the space occupied by the balls 4 and the cage 5. The seal 6 is an annular member including an annular core rod 6a and an elastic member 6b fixed to the core rod 6 a. The radially outer portion of each seal 6 is fixed to the outer ring 3 and its radially inner portion is slidably attached to the inner ring 2. The seal 6 suppresses leakage of the grease G to the outside.
The ball bearing 1 configured as described above has sealed therein grease G composed of the grease composition according to the embodiment of the present invention. Therefore, the rotational torque of the ball bearing 1 is small and the ball bearing 1 has a sufficient lubrication life. Further, such peeling of the white structure as described above is less likely to occur in the ball bearing 1.
Next, the grease composition forming the grease G will be described in detail. The grease composition forming grease G is a grease composition according to an embodiment of the present invention and contains a base oil, a thickener, and an organomodified polysiloxane. One of the technical features of the grease composition is that the grease composition contains an organic modified polysiloxane. Since the grease composition contains the organomodified polysiloxane, the occurrence of white structure flaking in the rolling bearing can be suppressed. As described above, this is because the grease composition containing the organomodified polysiloxane is capable of preventing an increase in internal stress at the rolling contact portion and suppressing the formation of a new surface due to wear.
In the grease composition, the base oil is an alkyl diphenyl ether. The grease composition is therefore suitable for providing a grease having satisfactory heat resistance and anti-flaking properties. The alkyl diphenyl ether may be a known alkyl diphenyl ether used as a base oil of a grease for a rolling bearing.
For example, the alkyl diphenyl ether may be an alkyl diphenyl ether having the following structural formulae (1) to (3).
Figure BDA0002214325000000051
(in the formula (1), R represents an alkyl group, R is bonded to a benzene ring.)
Figure BDA0002214325000000052
(in the formula (2), RaAnd RbRepresents an alkyl group. RaAnd RbEach bonded to a benzene ring. RaAnd RbMay be the same or different. )
Figure BDA0002214325000000053
(in the formula (3), RnRepresents an alkyl group, and m is an integer of 3 to 10. Each RnBonded to a benzene ring. A plurality of RnEach of which may be substituted with the remaining RnThe same or different. )
In the grease composition, the thickener is a urea thickener. Examples of urea thickeners include: urea compounds such as diurea, triurea, tetraurea, and polyurea (other than diurea, triurea, and tetraurea); a urea-urethane compound; carbamate compounds such as dicarbamate; and mixtures thereof. The urea thickener is preferably a diurea represented by the following structural formula (4).
R1-NHCONH-R2-NHCONH-R3…(4)
(in the formula (4), R1And R3Independently of one another and represents an amino residue and R2Representing the residue of a diisocyanate). The diurea represented by the above structural formula (4) is a compound of an amine compound and a diisocyanateA reaction product of (a).
Examples of the amine compound include alkylamine, alkylphenylamine, and cyclohexylamine. Examples of the diisocyanate compound include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates.
Specific examples of the diurea are reaction products of mixed amines and diisocyanate compounds. The mixed amine is a mixture of alkylphenylamine having an alkyl group of 8 to 16 carbon atoms and cyclohexylamine. In alkylphenylamine, the alkyl group may be a straight or branched alkyl group, and the phenyl group may be substituted with an alkyl group at any of the ortho, meta, and para positions. Specific examples of the alkylphenylamine include octylaniline, decylaniline, dodecylaniline, hexadecylaniline, and isododecylaniline. The alkylphenylamine is preferably p-dodecylaniline because of its satisfactory dispersibility. The cyclohexylamine content of the mixed amines is preferably from 91 to 99 mol%, based on the total amount of alkylphenylamine and cyclohexylamine. This is suitable for producing a grease composition having satisfactory lubricating film formability.
The diisocyanate compound is preferably an aromatic diisocyanate, as it is suitable for producing a grease composition having satisfactory heat resistance. Examples of the aromatic diisocyanate include diphenylmethane-4, 4' -diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, a mixture of 2, 4-tolylene diisocyanate and 2, 6-tolylene diisocyanate, and 3,3' -dimethyldiphenyl-4, 4' -diisocyanate. Among these, diphenylmethane-4, 4 '-diisocyanate and 2, 6-tolylene diisocyanate are preferable in view of their availability, and diphenylmethane-4, 4' -diisocyanate is more preferable because it has satisfactory heat resistance.
The reaction between the mixed amine and the diisocyanate compound may be carried out under various conditions to obtain the diurea represented by structural formula (4). However, it is preferable to cause a reaction between the mixed amine and the diisocyanate compound in the base oil because it produces a diurea compound having a high uniform dispersibility as the thickener. The reaction between the mixed amine and the diisocyanate compound may be performed in a base oil produced by adding a base oil in which the diisocyanate compound is dissolved to a base oil in which the alkylphenylamine and the cyclohexylamine are dissolved, or a base oil produced by adding a base oil in which the alkylphenylamine and the cyclohexylamine are dissolved to a base oil in which the diisocyanate compound is dissolved.
The temperature and time of the reaction between the mixed amine and the diisocyanate compound are not particularly limited, and conditions similar to those generally used in this type of reaction may be used. In view of the solubility and volatility of the mixed amine and diisocyanate compounds, the reaction temperature is preferably 60 ℃ to 170 ℃. The reaction time is preferably 0.5 to 2.0 hours to complete the reaction between the mixed amine and the diisocyanate compound and to shorten the time required to produce the grease composition. The reaction between the amino group of the mixed amine and the isocyanate group of the diisocyanate compound proceeds quantitatively, and it is preferable that the mixed amine and the diisocyanate compound are reacted at a molar ratio of 2: 1.
The diurea represented by the above structural formula (4) as the reaction product of the mixed amine and the diisocyanate compound is wherein R in the formula (4)1And R3Diureas each being an alkylphenylamine residue, wherein R1And R3Diureas which are all cyclohexylamine residues and wherein R1And R3A mixture of diureas in which one is an alkylphenylamine residue and the other is a cyclohexylamine residue.
The content of the thickener in the grease composition is 10 to 30 mass% based on the total amount of the base oil and the thickener. When the content of the thickener is less than 10% by mass, the thickener cannot sufficiently hold the base oil. Therefore, when the grease composition is used by being sealed in a rolling bearing, the grease composition may scatter or leak from the rolling bearing. When the content of the thickener is more than 30% by mass, the grease composition becomes hard. Therefore, when the grease composition is used by being sealed in a rolling bearing, the torque of the rolling bearing may increase and the seizure life (seschurlife) of the rolling bearing may be shortened due to the decrease in the fluidity of the grease composition. The content of the thickener is preferably 11 to 18 mass% based on the total amount of the base oil and the thickener.
The grease composition further contains an organomodified polysiloxane. The grease composition thus has excellent wettability to steel. Therefore, when the grease composition is used by sealing in a rolling bearing, the grease composition can easily enter between friction surfaces such as between the inner ring and the rolling elements and between the outer ring and the rolling elements. Thereby, occurrence of peeling of the white structure can be suppressed.
An example of the organically modified polysiloxane is a polysiloxane having a side chain modified with an organic group represented by the following structural formula (5).
Figure BDA0002214325000000081
(in the formula (5), R4Represents an alkyl group, m represents a positive integer, and n represents 0 or a positive integer). In the formula (5), R4May be the same or different, and the organic groups may be the same or different.
Examples of the organic group modifying the side chain of the polysiloxane represented by structural formula (5) include aralkyl groups and (poly) ether groups having one or more ether bonds. The aralkyl group is not particularly limited as long as one of the hydrogen atoms of the alkyl group is substituted with an aryl group such as a phenyl group. Specific examples of the aralkyl group are aralkyl groups represented by the following structural formula, such as- (CH)2)a-Ph (wherein Ph represents a phenyl group and a represents an integer of 1 or more) and- (CH)2)b-CH(CH3) -Ph (wherein Ph represents phenyl and b represents 0 or an integer of 1 or more).
Examples of the (poly) ether group include a functional group having an alkylene oxide group such as an ethylene oxide group "- (C)2H4O) - "or propylene oxide group" - (C)3H6O) - ". Specific examples of such functional groups are represented by the formula-R5(C2H4O)c(C3H6O)dR6A functional group represented by the structural formula (II) (wherein R is5Represents a single bond, alkylene or alkylene oxide group, R6Represents hydrogen, an alkyl group or an aryl group, c and d are independent of each other and represent 0 or an integer of 1 or more (except the case where c and d are both 0)).
The organo-modified polysiloxane is preferably at least one selected from the group consisting of aralkyl-modified polymethylalkylsiloxane and polyether-modified polydimethylsiloxane because they are highly compatible with the base oil and are suitable for providing heat resistance required for the grease composition. Commercially available organomodified polysiloxanes can be used.
Specific examples of the aralkyl-modified polymethylalkylsiloxane include BYK-322 (manufactured by BYK Additives & Instruments), BYK-323 (manufactured by BYK Chemical Additives & Instruments), KF-410 (manufactured by Shin-Etsu Chemical Co., Ltd.), X-22-2516 (manufactured by Shin-Etsu Chemical Co., Ltd.), and X-22-1877 (manufactured by Shin-Etsu Chemical Co., Ltd.).
Specific examples of the polyether-modified polydimethylsiloxane include BYK-330 (manufactured by Pickering Chemicals and instruments), BYK-331 (manufactured by Pickering Chemicals and instruments), KF-351A (manufactured by shin-Etsu chemical industries, Ltd.), KF-352A (manufactured by shin-Etsu chemical industries, Ltd.), KF-353 (manufactured by shin-Etsu chemical industries, Ltd.), KF-354L (manufactured by shin-Etsu chemical industries, Ltd.), KF-355A (manufactured by shin-Etsu chemical industries, Ltd.), KF-615A (manufactured by shin-Etsu chemical industries, Ltd.), KF-945 (manufactured by shin-Etsu chemical industries, Ltd.), KF-640 (manufactured by shin-Etsu chemical industries, Ltd.), KF-642 (manufactured by shin-Etsu chemical industries, Ltd.) KF-643 (manufactured by shin-Etsu chemical Co., Ltd.), KF-644 (manufactured by shin-Etsu chemical Co., Ltd.), KF-6020 (manufactured by shin-Etsu chemical Co., Ltd.), KF-6204 (manufactured by shin-Etsu chemical Co., Ltd.), and X-22-2516 (manufactured by shin-Etsu chemical Co., Ltd.).
The content of the organomodified polysiloxane in the grease composition is 0.2 to 10 mass% based on the total amount of the base oil and the thickener. When the content of the organomodified polysiloxane is less than 0.2% by mass, there is little effect of adding the organomodified polysiloxane. When the content of the organomodified polysiloxane is more than 10 mass%, the grease composition is soft. Therefore, when the grease composition is used by being sealed in a rolling bearing, the rolling bearing may have reduced leakage resistance of the grease composition and torque may increase due to an increase in fluid resistance. The content of the organomodified polysiloxane is preferably 0.5 to 5 mass% based on the total amount of the base oil and the thickener.
Various additives such as an antioxidant, an extreme pressure additive, an antiwear agent, a dye, a color tone stabilizer, a tackifier, a structure stabilizer, a metal deactivator, a viscosity index improver, and an antirust additive may be added to the grease composition as appropriate within a range in which the effects of the present invention are not reduced or eliminated. In the case where the grease composition contains these additives, it is preferable that the total content of the additives in the grease composition is 10 mass% or less based on the total amount of the base oil and the thickener.
The grease composition of the present invention can be used in those parts requiring grease lubrication and is suitable as a grease for rolling bearings. The grease composition of the present invention is particularly suitable as a grease for a rolling bearing which is required to have anti-flaking property against a white structure. The grease composition is therefore suitable for use as a grease to be sealed in rolling bearings used in severe environments, such as automotive electrical parts such as alternators, electromagnetic clutches for automotive air conditioners, intermediate pulleys, and electric fan motors, and automotive engine auxiliary devices, and the like.
Next, a manufacturing method of the grease composition will be described. For example, the grease composition may be prepared by: first a base grease consisting of a base oil and a thickener is prepared, and then the organomodified polysiloxane and any desired additives contained in the grease composition as required are added to the base grease,
and they are mixed together by stirring in a planetary centrifugal mixer or the like.
The present invention is not limited to the above-described embodiments and may be embodied in other forms. The rolling bearing according to the embodiment of the present invention is not limited to the ball bearing in which the grease composition according to the embodiment of the present invention is sealed. The rolling bearing according to the embodiment of the present invention may be any other rolling bearing using rolling elements other than balls, such as needle roller bearings or roller bearings, as long as the rolling bearing has the grease composition according to the embodiment of the present invention sealed therein.
The present invention will be described in more detail based on examples. However, the present invention is not limited to these examples. A plurality of grease compositions were prepared and the characteristics of each grease composition were evaluated. The composition and evaluation results of each grease composition are shown in table 1.
The following materials were used in examples and comparative examples.
Diisocyanate compound
MDI: diphenylmethane-4, 4' -diisocyanate
Amine Compound
CHA: cyclohexylamine
PDA: p-dodecyl aniline
Base oil
ADE: an alkyldiphenyl ether (MORESCO-HILUBE LB-100 manufactured by MORESCO Corporation, Morisco), having a dynamic viscosity of 102mm at 40 deg.C2/s。
Organo-modified polysiloxanes
Aralkyl-modified polymethylalkylsiloxane (1): BYK-322 (made by Bick chemical auxiliary and Instrument Ministry)
Aralkyl-modified polymethylalkylsiloxane (2): BYK-323 (made by Bike chemical auxiliary and Instrument Ministry)
Polyether-modified polydimethylsiloxane (1): BYK-330 (made by Bick chemical auxiliary and Instrument Ministry)
Polyether-modified polydimethylsiloxane (2): BYK-331 (made by Bick chemical auxiliary and Instrument Ministry)
Comparative example 1
(1) Amine compounds (CHA and PDA) as thickener materials and half the amount of ADE corresponding to the base oil content shown in table 1 were mixed so that the resulting mixture had the CHA and PDA contents shown in table 1. The mixture was heated to 100 ℃ to dissolve the CHA and PDA in the ADE. Thus, solution a was prepared.
(2) In addition to the solution a, a diisocyanate compound (MDI) as a thickener material and a half amount of ADE corresponding to the base oil content shown in table 1 were mixed so that the resulting mixture had the MDI content shown in table 1. The mixture was heated to 100 ℃ to dissolve the MDI in the ADE. Thus, solution B was prepared.
(3) While stirring solution B, solution a was slowly added to solution B. Thereafter, the resulting solution was kept at 150 ℃ for 30 minutes. The solution was then allowed to cool to room temperature while stirring was continued.
(4) Finally, the solution thus cooled to room temperature was homogenized on a three-roll mill to prepare a grease composition.
(example 1)
A mixture of a base oil and a thickener was prepared by a procedure similar to that of (1) to (3) of comparative example 1, and BYK-322 was added to the mixture so that the resulting mixture had a BYK-322 content shown in table 1. Thereafter, the mixture was mixed in a mixer at 2,000rpm, and then homogenized on a three-roll mill to prepare a grease composition.
(example 2)
Grease compositions were prepared by a procedure similar to that of example 1, except that the amount of BYK-322 was varied so that the mixture had the BYK-322 content shown in Table 1.
(example 3)
A grease composition was prepared by a procedure similar to that of example 2, except that BYK-323 was used as an additive instead of BYK-322.
(example 4)
A grease composition was prepared by a procedure similar to that of example 2, except that BYK-330 was used as an additive instead of BYK-322.
(example 5)
A grease composition was prepared by a procedure similar to that of example 2, except that BYK-331 was used as an additive instead of BYK-322.
(evaluation of grease composition)
The grease compositions prepared in examples 1 to 5 and comparative example 1 were evaluated. The results are shown in table 1 and fig. 2.
[ Table 1]
Figure BDA0002214325000000131
The evaluations shown in table 1 were performed by the following methods.
(1) The needle penetration (60W) after work was measured by the method according to JIS K2220-7.
(2) Cumulative hydrogen generation amount ratio
The friction tests of the grease compositions prepared in examples 1 to 5 and comparative example 1 were performed using a vibration friction wear tester (SRV-IV) manufactured by Optimol Instruments, and the amount of hydrogen generated was measured as the cumulative hydrogen generation amount. Test conditions using the vibration friction abrasion tester are shown in table 2.
[ Table 2]
Figure BDA0002214325000000141
The cumulative hydrogen production was measured using Transpector CPM, a quadrupole mass spectrometer, manufactured by inflon co. A special nozzle (1.5 meter capillary assembly kit) was attached to the quadrupole mass spectrometer and the tip of the nozzle was placed near the test piece (steel ball and circular plate) on the vibrating friction wear tester. Thereby measuring the hydrogen generated during the test. The measurement was performed under the following conditions.
Ionization voltage: 70eV
Ionization current: 500 muA
Analysis time: 30 minutes
In table 2 and fig. 2, the hydrogen generation amounts (cumulative hydrogen generation amounts) of examples 1 to 5 are shown as ratios to the hydrogen generation amount (cumulative hydrogen generation amount) of comparative example 1.
As can be seen from the results of examples 1 to 5 and comparative example 1, the use of the grease composition according to the embodiment of the present invention can reduce the cumulative hydrogen generation amount. Therefore, the grease composition sealed in the rolling bearing can suppress the occurrence of the peeling of the white structure of the rolling bearing.

Claims (4)

1. A grease composition (G), characterized by comprising:
a base oil, said base oil being an alkyl diphenyl ether;
a thickener which is a urea thickener, the grease composition (G) containing 10 to 30 mass% of the thickener based on the total amount of the base oil and the thickener; and
an organomodified polysiloxane, the grease composition (G) containing 0.2 to 10 mass% of the organomodified polysiloxane, based on the total amount of the base oil and the thickener.
2. A grease composition (G) according to claim 1, characterized in that the organo-modified polysiloxane is at least one selected from the group consisting of aralkyl-modified polymethylalkylsiloxane and polyether-modified polydimethylsiloxane.
3. Rolling bearing (1) characterized by comprising a grease composition (G) sealed in said rolling bearing (1), wherein
The grease composition (G) contains a base oil, a thickener and an organomodified polysiloxane;
the base oil is alkyl diphenyl ether;
the thickener is a urea thickener, and the grease composition (G) contains 10 to 30 mass% of the thickener based on the total amount of the base oil and the thickener; and is
The grease composition (G) contains 0.2 to 10 mass% of the organomodified polysiloxane based on the total amount of the base oil and the thickener.
4. Rolling bearing (1) according to claim 3, characterized in that said organo-modified polysiloxane is at least one selected from the group consisting of aralkyl modified polymethylalkylsiloxanes and polyether modified polydimethylsiloxanes.
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