JP2009209179A - Grease composition and rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition which can more inhibit the change of a thickening degree and the separation of oil at a high temperature, is not solidified at the ultralow temperature of -40°C, and exhibits better characteristics than those of conventional grease compositions in a temperature range of from a high temperature to an ultralow temperature, and to provide a rolling device in which the grease composition is sealed, and which is excellent in durability at a high temperature, and can be operated without noises even at the ultralow temperature of -40°C. <P>SOLUTION: The grease composition contains a base oil comprising at least one of dialkyldiphenyl ether oils, ester-based synthetic oils and poly α-olefin oils, containing a mixture comprising: the first diurea compound; the second diurea compound having specific structures, respectively, in a (molar) ratio of 30:70 to 90:10 in an amount of 10 to 30 mass% based on the total amount of the grease composition as a thickening agent, and containing a specific additive in an amount of 0.1 to 5 mass% based on the total amount of the crease composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grease composition using a diurea compound as a thickener and a rolling device.

  2. Description of the Related Art In recent years, automobiles and industrial machines have become smaller and lighter with higher performance, and built-in rolling bearings tend to be exposed to higher temperatures. Therefore, it is necessary to enclose a grease composition having excellent heat resistance and oxidation stability in the rolling bearing.

  As high-temperature grease compositions, metal composite soaps, sodium terephthalate, benton, and urea compounds containing thickeners and fluorine grease compositions have been used so far. However, the metal composite soap-based grease composition is easy to cure with time, the sodium terephthalate grease composition has a large oil separation, the Benton grease composition has a problem in lubricity, and the fluorine grease composition is expensive. There are some disadvantages, and urea-based grease compositions have become mainstream.

  As urea-based grease compositions, diurea-based grease compositions and tetraurea-based grease compositions are widely used. However, tetraurea-based grease compositions are hardened when exposed to high temperatures for a long period of time. There is a problem in the consistency of consistency such as hardening or softening due to the difference in speed.

  On the other hand, it has been found that the properties of diurea-based grease compositions vary greatly depending on the structures of isocyanate and amine as a terminal group. For example, a diurea grease composition using a diurea compound having a urea bond at both ends of a diphenylmethane group and a diurea compound having a urea bond at both ends of a tolylene group or a bitolylene group (see Patent Document 1), a tolylene group, a diphenylmethane group The straight-chain saturated alkyl group having 6 to 18 carbon atoms is 25 to 45 mol%, the cyclohexyl group is 50 to 70 mol%, and the aromatic hydrocarbon group is 5 to 25 mol% at both ends of the dimethylbiphenylene group. A diurea grease composition obtained by reacting two or more different diisocyanates and amines (see Patent Document 3), and three kinds of diurea compounds. A diurea-based grease composition (see Patent Document 4) used by mixing is known.

JP-A-1-13969 JP-A-6-88085 Japanese Patent No. 2777728 JP 2003-201495 A

  However, the diurea grease composition including the above-mentioned diurea grease composition has room for improvement in fluidity at low temperatures. In particular, since automobiles are used even in cold regions, problems such as abnormal noise occurring at low temperatures occur. Further, higher performance and miniaturization of automobiles and industrial machines are inevitable, and stability at higher temperatures is also required. Another object of the present invention is to provide a rolling device that is sealed with the grease composition, has excellent durability at high temperatures, and can operate without generating noise even at an extremely low temperature of −40 ° C. To do.

  Therefore, the present invention can further suppress the change in consistency and oil separation at high temperature, and does not solidify even at an extremely low temperature of −40 ° C., and has better characteristics than before in a wide temperature range from high temperature to extremely low temperature. It aims at providing the grease composition which shows this.

In order to achieve the above object, the present invention provides the following grease composition and rolling device.
(1) A base oil composed of at least one of dialkyl diphenyl ether oil, ester-based synthetic oil, and poly-alpha olefin oil, as a thickener, a first diurea compound represented by the following general formula (I), Grease composition comprising a mixture obtained by mixing the second diurea compound represented by the formula (II) at a ratio (molar ratio) of first diurea compound: second diurea compound = 30: 70 to 90:10 Calcium carbonate with a primary average particle size of 0.1 μm or less, sulfur-phosphorus extreme pressure agent containing no metal element, organic zinc compound, amine rust prevention Agent, carboxylic acid rust inhibitor, ester rust inhibitor, carbonate and benzoate, each containing 0.1 to 5% by mass of the total amount of the grease composition. Grease assembly Thing

(R ₂ in the formula represents a tolylene group or a bi-tolylene group. R ₁ is an aromatic hydrocarbon group having 6 to 20 carbon atoms, which may be the same or different.)

(R ₄ in the formula represents a diphenylmethane group. R ₃ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, which may be the same or different.)
(2) A method for producing a grease composition as described in (1) above, wherein the base oil and the compound containing R _{1 to} R ₄ are mixed in a single container with the first diurea compound and the second diurea compound. In which the first diurea compound and the second diurea compound are synthesized at the same time.
(3) A rolling device comprising an inner member, an outer member, and a plurality of rolling elements that are arranged to roll between the inner member and the outer member. A rolling device characterized in that the grease composition described in the above (1) is filled in a gap formed between a member and the outer member and in which the rolling element is provided.

  The grease composition of the present invention uses a thickener in which the first diurea compound and the second diurea compound each having a specific structure are mixed in a specific ratio, so that the consistency change and oil separation at a high temperature can be further suppressed. It does not solidify even at an extremely low temperature of −40 ° C., and exhibits better characteristics than before in a wide temperature range from a high temperature to an extremely low temperature. Moreover, durability can be improved by adding a specific additive.

  Hereinafter, the present invention will be described in detail.

[Base oil]
In the grease composition of the present invention, as the base oil, dialkyldiphenyl ether oil, ester-based synthetic oil, and poly-α-olefin oil are used alone or in combination.

As the dialkyl diphenyl ether oil, those represented by the following general formula (III) are preferable.

In the formula, one of R ₅ , R ₆ and R ₇ is a hydrogen atom, and the remaining two are the same or different alkyl groups. 8-20 are preferable and, as for carbon number of an alkyl group, 12-14 are more preferable.

  Examples of ester synthetic oils include diesters such as di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, polyol esters such as trimethylolpropane caprylate, pentaerythritol-2-ethylhexanoate, and trioctyl. Examples include trimellitic acid esters such as trimellitate and tridecyl trimellitate, and aromatic ester oils of pyromellitic acid esters such as tetraoctyl pyromellitate.

  The poly α-olefin oil is preferably represented by the following general formula (IV).

In the formula, R ₈ is an alkyl group, and two or more different alkyl groups may be mixed in the same molecule, but is preferably an n-octyl group. N is preferably an integer of 3 to 8.

The base oil preferably has a kinematic viscosity at 40 ° C. of 15 to 200 mm ² / s, but is more preferably 20 to 150 mm 2 / s in consideration of lubrication characteristics, evaporation characteristics, and low temperature fluidity. In addition, when combining dialkyl diphenyl ether oil, ester synthetic oil, and poly alpha olefin oil, it adjusts to said viscosity with mixed oil.

[Thickener]
As the thickener, a mixture of a first diurea compound represented by the following general formula (I) and a second diurea compound represented by the following general formula (II) is used.

In the formula, R ₂ represents a tolylene group or a bitolylene group. R ₁ is an aromatic hydrocarbon group having 6 to 20 carbon atoms, which may be the same or different. Such a diurea compound can be obtained by reacting tolylene diisocyanate or vitorylene diisocyanate with an aromatic amine such as aniline, benzylamine, toluidine, chloroaniline, dodecylaniline. In addition, 2,4-tolylene dianocyanate, 2,6-tolylene diisocyanate, or a mixture thereof can be used as tolylene diisocyanate, and 3,3'- as the tolylene diisocyanate. Vitrylene-4,4′-diisocyanate and the like can be used.

In the formula, R ₄ represents a diphenylmethane group. R ₃ is an aromatic hydrocarbon group having 6 to 12 carbon atoms and may be the same or different. Such a diurea compound can be obtained by reacting diphenylmethane diisocyanate such as diphenylmethane 4,4′-diisocyanate with an aromatic amine such as aniline, benzylamine, toluidine, chloroaniline, and dodecylaniline.

  The mixing ratio of the first diurea compound and the second diurea compound is a molar ratio of first diurea compound: second diurea compound = 30: 70 to 90:10, and 40:60 to 70:30. It is preferable that If the first diurea compound is less than 30%, heat curing tends to occur, and if it exceeds 90%, oil separation increases, which is not preferable.

  Further, the amount of the thickener is 10 to 30% by mass of the total amount of grease, more preferably 15 to 25% by mass, and particularly preferably 15 to 21% by mass. If the amount of the thickener is less than 10% by mass, the grease state cannot be maintained, and if it exceeds 30% by mass, it becomes too hard to exhibit a sufficient lubrication state.

  Further, the penetration of the grease composition is preferably 300 or less.

〔Additive〕
The grease composition includes calcium carbonate having a primary average particle size of 0.1 μm or less (hereinafter referred to as “calcium carbonate fine particles”), sulfur-phosphorus extreme pressure agent containing no metal element, an organic zinc compound, and an amine rust inhibitor. It is preferable to blend at least one of carboxylic acid-based rust preventive, ester-based rust preventive, carbonate and benzoate.

(Calcium carbonate fine particles)
The fine calcium carbonate particles may be known, and heavy calcium carbonate obtained from nature or precipitated calcium carbonate obtained by synthesis so as to have the above-mentioned primary average particle diameter can be used. Further, the primary average particle diameter is preferably 0.05 μm or less.

  In addition, the calcium carbonate fine particles may be added to the base oil as they are, but the calcium carbonate fine particles are one or more surface treatments selected from fatty acids such as stearic acid, rosin, carboxy-modified polymers, and metallic surface treatment agents. It is preferable to perform a surface treatment in advance with an agent. By doing so, the compatibility with the base oil can be improved, and the dispersion stability of the calcium carbonate fine particles can be improved. Surface treatment of calcium carbonate fine particles refers to coating the surface of calcium carbonate fine particles with a surface treatment agent. Such surface-treated calcium carbonate fine particles are, for example, calcium carbonate fine particles in a state of being dispersed in water. It can be prepared by adding a surface treatment agent to the mixture and stirring and dispersing it, followed by dehydration, drying and pulverization.

  The content of the calcium carbonate fine particles is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, the effect of extending the durability cannot be obtained. If the content exceeds 5% by mass, the function is lost due to heat generation or the like, which is not practical.

(Sulfur-phosphorus extreme pressure agent)
Sulfur-phosphorus extreme pressure agents are compounds that do not contain metal elements and contain phosphorus atoms and sulfur atoms, and have both phosphorus atoms and sulfur atoms in the molecule, such as thiophosphates and thiophosphites. In addition, for example, a mixture of a phosphorus extreme pressure agent (having a phosphorus atom in the molecule) and a sulfur extreme pressure agent (having a sulfur atom in the molecule) may be used. Examples of the thiophosphates include thiophosphates having a basic structure of thiophosphate such as triphenylphosphothioate (TPPT). Examples of thiophosphites include organic trithiophosphites represented by (RS) ₃ P such as tributyltrithiophosphite and tri (2-ethylhexyl) trithiophosphite.

  The content of the sulfur-phosphorus extreme pressure agent is preferably 0.1 to 5% by mass, more preferably 1 to 3% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, the change in consistency is large when used at a high temperature for a long time, and if it exceeds 5% by mass, oil separation becomes large and thermal stability becomes poor, which is not practical.

(Organic zinc compound)
Examples of the organic zinc compound include zinc dialkyldithiocarbamate (ZnDTC) and zinc dialkyldithiophosphate (ZnDTP). Among them, the following zinc dialkyldithiocarbamate (ZnDTC) is preferable.

In the formula, R ₉ is an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, or an arylalkyl group, and they may all be the same or different. Among them, 1,1,3,3-tetramethylbutyl group, 1,1,3,3-tetramethylhexyl group, 1,1,3-trimethylhexyl group, 1,3-dimethylbutyl group, 1-methylundecane Group, 1-methylhexyl group, 1-methylpentyl group, 2-ethylbutyl group, 2-ethylhexyl group, 2-methylcyclohexyl group, 3-heptyl group, 4-methylcyclohexyl group, n-butyl group, isobutyl group, isopropyl Group, isoheptyl group, isopentyl group, undecyl group, eicosyl group, ethyl group, octadecyl group, octyl group, cyclooctyl group, cyclododecyl group, cyclopentyl group, dimethylcyclohexyl group, decyl group, tetradecyl group, docosyl group, dodecyl group, Tridecyl group, trimethylcyclohexyl vessel, nonyl group, propyl group, Sadecyl, hexyl, henicosyl, heptadecyl, heptyl, pentadecyl, pentyl, methyl, tert-butylcyclohexyl, tert-butyl, 2-hexenyl, 2-methallyl, allyl, undecenyl Oleyl group, decenyl group, vinyl group, butenyl group, hexenyl group, heptadecenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, tertiary butylphenyl group, secondary pentylphenyl group, n-hexylphenyl group, tertiary Octylphenyl group, isononylphenyl group, n-dodecylphenyl group, phenyl group, benzyl group, 1-phenylmethyl group, 2-phenylmethyl group, 3-phenylpropyl group, 1,1-dimethylbenzyl group, 2-phenyl Isopropyl group, 3-phenylhexyl group, benzhydryl group Biphenyl group, and the like are preferable. Further, these groups may have an ether group.

  The content of the organozinc compound is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, a sufficient effect cannot be obtained, and even if the content exceeds 5% by mass, further improvement of the effect cannot be obtained.

(Amine-based rust preventive)
Examples of the amine-based rust preventive include alkoxydiphenylamine, fatty acid amine salt, and partial amide of dibasic carboxylic acid, but fatty acid amine salt is preferable.

  The content of the amine-based rust inhibitor is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, a sufficient effect cannot be obtained, and even if the content exceeds 5% by mass, further improvement of the effect cannot be obtained.

(Carboxylic acid anticorrosive)
Examples of carboxylic acid-based rust preventives include monocarboxylic acids such as lauric acid and stearic acid, linear fatty acids such as lauric acid, and saturated carboxylic acids having a naphthenic nucleus. Dicarboxylic acids include succinic acid, alkyl succinic acid, and alkyl succinic acid half ester. Succinic acid derivatives such as alkenyl succinic acid, alkenyl succinic acid half ester, succinimide, hydroxy fatty acid, mercapto fatty acid, sarcosine derivative, or oxidized wax such as wax or petrolatum oxide. Esters are preferred.

  The content of the carboxylic acid-based rust inhibitor is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, a sufficient effect cannot be obtained, and even if the content exceeds 5% by mass, further improvement of the effect cannot be obtained.

(Ester rust inhibitor)
Examples of ester-based rust preventives include sorbitol, pentaerythritol, sucrose, glyceric acid polyhydric alcohols and carboxylic acid partial esters such as oleic acid, lauric acid, and higher fatty acid alcohols such as oleyl alcohol, stearyl alcohol, and lauryl alcohol. Of these, sorbitol is preferred.

  The content of the ester rust inhibitor is preferably from 0.1 to 5% by mass, more preferably from 0.5 to 2% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, a sufficient effect cannot be obtained, and even if the content exceeds 5% by mass, further improvement of the effect cannot be obtained.

(Carbonate)
Examples of the carbonate include, but are not limited to, ZnCO ₃ , Li ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Na ₂ CO _{3 and the} like.

  The content of carbonate is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, a sufficient effect cannot be obtained, and even if the content exceeds 5% by mass, further improvement of the effect cannot be obtained.

(Benzoate)
Examples of benzoates include, but are not limited to, nitro derivatives of benzoic acid, ammonium benzoate, hydroxybenzoic acid, sodium benzoate, and the like.

  The benzoate content is preferably 0.1 to 5% by mass, more preferably 0.5 to 1% by mass, based on the total amount of the grease composition. If the content is less than 0.1% by mass, a sufficient effect cannot be obtained, and even if the content exceeds 5% by mass, further improvement of the effect cannot be obtained.

(Other)
In addition to the above additives, for example, amines such as phenyl-1-naphthylamine, phenols such as 2,6-di-tert-dibutylphenol, sulfur-based antioxidants; extreme pressure agents such as organic molybdenum; fatty acids, Oiliness improvers such as animal and vegetable oils and montanic acid wax; metal deactivators such as benzotriazole and the like can be added alone or in admixture of two or more. In addition, the addition amount of these additives will not be specifically limited if it is a grade which does not impair the objective of this invention.

〔Production method〕
There is no limitation on the method for producing the grease composition, but the base oil and the compound containing R _{1 to} R ₄ are mixed in the first diurea compound and the second diurea compound in the above-mentioned mixing ratio in a single container, and It is preferable to synthesize the first diurea compound and the second diurea compound at the same time by adding and reacting with the amount of the thickener. Thereby, the first diurea compound and the second diurea compound are uniformly dispersed in the grease composition. As a result, the amount of the thickener can be reduced, the amount of the base oil is relatively increased and the lubricity is excellent, and the hardening of the grease can be suppressed even at a low temperature of −40 ° C. In addition, a grease composition using a base oil in common and using a first diurea compound as a thickener and a grease composition using a second diurea compound as a thickener are synthesized separately, Although a method of mixing the diurea compound and the second diurea compound so as to have the above-mentioned mixing ratio is possible, the dispersion state of the first diurea compound and the second diurea compound is worse than that of the former production method. Become.

(Rolling device)
The present invention also relates to a rolling device in which the above grease composition is enclosed. Examples of the rolling device include a rolling bearing, a ball screw, a linear guide device, and a linear motion bearing.

  FIG. 1 is a longitudinal sectional view showing a structure of a ball bearing which is an embodiment of a rolling device. The ball bearing 1 includes an inner ring 10 that is an inner member, an outer ring 11 that is an outer member, a plurality of balls 13 that are rotatably disposed between the inner ring 10 and the outer ring 11, and a plurality of balls. 13, and a contact type seal 14, 14 attached to the outer ring 11. The bearing space surrounded by the inner ring 10, the outer ring 11, and the seals 14 and 14 is filled with the above grease composition G, and is sealed in the ball bearing 1 by the seal 14. Due to the properties of the grease composition G, it has excellent durability at high temperatures, and operates without generating noise even at an extremely low temperature of −40 ° C. Therefore, it is particularly suitable for automobile electrical parts such as an alternator and an electromagnetic clutch, and automobile engine accessories such as an idler pulley.

  As the rolling bearing, in addition to the ball bearing, for example, a radial rolling bearing such as an angular ball bearing, a self-aligning ball bearing, a cylindrical roller bearing, a tapered roller bearing, a needle roller bearing, or a self-aligning roller bearing. Thrust-type rolling bearings such as bearings, thrust ball bearings, thrust roller bearings and the like can be mentioned, and the above grease composition is similarly encapsulated.

  In other rolling devices, the inner member means a screw shaft in the case of a ball screw, a guide rail in the case of a linear guide device, and a shaft in the case of a linear motion bearing. The outer member means a nut in the case of a ball screw, a slider in the case of a linear guide, and an outer cylinder in the case of a linear motion bearing. The above grease composition is similarly encapsulated in these rolling devices.

  EXAMPLES The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

(Examples 1-7, Comparative Examples 1-5)
As shown in Tables 1 and 2, the first diurea compound and the second diurea compound were simultaneously synthesized in the base oil, and additives were added to prepare test greases. And the following tests were done using each test grease.

(1) Bearing leakage test A test bearing is manufactured by filling a deep groove ball bearing with an inner diameter of 8 mm, an outer diameter of 22 mm, and a width of 7 mm (see FIG. 1) with test grease so as to occupy 50% of the bearing space. The test bearing was mounted on a test machine similar to the ASTM D1741 bearing life tester as shown in FIG. Then, the bearing was rotated at a rotational speed of 3000 min ⁻¹ under conditions of a bearing temperature of 180 ° C. and an axial load of 59 N (other conditions conformed to ASTM D1741), and the leakage rate from the bearing after 24 hours was measured. Although a result is shown in Table 1 and Table 2, 80 mass% or less is set as a pass.
(2) Durability test A test bearing was prepared by filling a deep groove ball bearing with an inner diameter of 8 mm, an outer diameter of 22 mm, and a width of 7 mm (see Fig. 1) with test grease to occupy 50% of the bearing space. The bearings were mounted in a tester similar to ASTM D1741 bearing life tester as shown in FIG. Then, rotating at a rotational speed of 3000 min ⁻¹ under conditions of a bearing temperature of 180 ° C. and an axial load of 59 N (other conditions conform to ASTM D1741) until seizure occurs and the temperature of the outer ring rises to 190 ° C. or higher. Was measured (burn-in time). The results are shown in Tables 1 and 2, and are shown as relative values with the seizure time of Comparative Example 1 as 1.

(Examples 8-15, Comparative Examples 6-8)
As shown in Tables 3 to 4, the first diurea compound and the second diurea compound were simultaneously synthesized in the base oil, and additives were added to prepare a test grease. And said (1) bearing leak test and (2) endurance test were done. Although a result is shown to Tables 3-4, it was set as the relative value with respect to the comparative example 6 in the endurance test.

  From the above tests, according to the present invention, a mixture obtained by simultaneously synthesizing the first diurea compound and the second diurea compound in a ratio (molar ratio) of 30:70 to 90:10 was specified as a thickener. It can be seen that each of the test greases of Examples containing these additives is excellent in thermal oxidative stability at high temperatures.

(Examples 16 to 20, Comparative Examples 9 to 13)
As shown in Table 5 and Table 6, in Examples 16 to 20 and Comparative Examples 9 to 10, test greases were prepared by simultaneously synthesizing the first diurea compound and the second diurea compound in the base oil. In Comparative Examples 12 and 13, the first diurea compound and the second diurea compound were separately prepared, and both were mixed to prepare a test grease. In each test grease, amine-based rust preventive agent is 2% by mass of the total amount of grease, organozinc compound is 1% by mass of the total amount of grease, and benzotriazole-based metal deactivator is 0.05% by mass of the total amount of grease. Added. Each test grease was subjected to the following (3) low temperature abnormal noise test and (4) seizure life test.

(3) Low temperature abnormal noise test A test bearing was produced by enclosing a test grease in a bearing having an inner diameter of 17 mm, and the abnormal noise was measured at -40 ° C. The measurement was carried out 10 times for each test bearing, and those with an abnormal noise occurrence probability of 10% or less (1 time or less) were accepted. The results are shown in Tables 6 and 7. Moreover, the relationship between the ratio of the 2nd diurea compound obtained based on the measurement result of Examples 16-19 and Comparative Examples 9-11 and abnormal noise generation probability is shown in FIG.
(4) Baking life test 6305 ball bearings (outer diameter 62 mm, inner diameter 25 mm, width 17 mm) equipped with heat-resistant rubber seals were filled with test grease so as to occupy 30% of the bearing space to produce test bearings. This test bearing is considered to be seized when the inner ring is continuously rotated at 15000 min-1 at an outer ring temperature of 180 ° C., radial load of 98 N, and axial load of 98 N, and the temperature rise and motor current value (torque) rise. Was measured. Three test bearings were used, and the average value was obtained. The results are shown in Tables 5 and 6, and relative values to Example 19, and the ratio of the second diurea compound obtained based on the measurement results of Examples 16 to 19 and Comparative Examples 9 to 11 The relationship with the seizure life ratio is shown in FIG.

  From the above tests, according to the present invention, a mixture obtained by simultaneously synthesizing the first diurea compound and the second diurea compound in a ratio (molar ratio) of 30:70 to 90:10 was specified as a thickener. It can be seen that each of the test greases of Examples containing the above additives has no abnormal noise at a low temperature and has an excellent baking life. Further, in the methods of preparing and mixing the first diurea compound and the second diurea compound separately from Comparative Examples 12 and 13, abnormal noise is easily generated at low temperatures.

It is sectional drawing which shows the ball bearing which is an example of the rolling device which concerns on this invention. It is sectional drawing which shows the structure of the testing machine used for the durability test in the Example. It is a graph which shows the relationship between the ratio of a 2nd diurea compound, and abnormal noise generation probability. It is a graph which shows the relationship between the ratio of a 2nd diurea compound, and a baking lifetime ratio.

Explanation of symbols

1 Ball bearing 10 Inner ring 11 Outer ring 13 Ball

Claims (8)

A base oil composed of at least one of dialkyl diphenyl ether oil, ester-based synthetic oil, and poly-α-olefin oil, and as a thickener, a first diurea compound represented by the following general formula (I) and the following general formula (II ) And the second diurea compound represented by the formula (1): a first diurea compound: second diurea compound = 30: 70 to 90:10 (molar ratio). Calcium carbonate blended at a ratio of 10 to 30% by mass and having a primary average particle size of 0.1 μm or less, sulfur-phosphorus extreme pressure agent containing no metal element, organic zinc compound, amine-based rust inhibitor, carvone Grease composition characterized by containing at least one of acid rust inhibitor, ester rust inhibitor, carbonate and benzoate at a ratio of 0.1 to 5% by mass of the total amount of the grease composition.

(R ₂ in the formula represents a tolylene group or a bi-tolylene group. R ₁ is an aromatic hydrocarbon group having 6 to 20 carbon atoms, which may be the same or different.)

(R ₄ in the formula represents a diphenylmethane group. R ₃ is an aromatic hydrocarbon group having 6 to 12 carbon atoms, which may be the same or different.)   2. The grease composition according to claim 1, wherein the grease composition is obtained by synthesizing the first diurea compound and the second diurea compound simultaneously in the same container.   The grease composition according to claim 1 or 2, wherein the calcium carbonate is surface-treated with one or more substances selected from a fatty acid, a resin acid, a rosin acid and a metal-based surface treatment agent.   The grease composition according to claim 1 or 2, wherein the sulfur-phosphorus extreme pressure agent is thiophosphate or thiophosphite.   The grease composition according to claim 1 or 2, wherein the amine-based rust inhibitor is an alkoxyphenylamine, an amine salt of a fatty acid, or a partial amide of a dibasic carboxylic acid.   The grease composition according to claim 1 or 2, wherein the benzoate is a nitro derivative of benzoic acid, ammonium benzoate, hydroxybenzoic acid or sodium benzoate. It is a manufacturing method of a grease constituent given in any 1 paragraph of Claims 1-6,
Put a base oil and a compound containing R _{1 to} R ₄ in a single container so that the first diurea compound and the second diurea compound are in the mixing ratio and the amount of the thickener. A production method comprising simultaneously synthesizing a first diurea compound and a second diurea compound.   A rolling device comprising: an inner member; an outer member; and a plurality of rolling elements that are freely rollable between the inner member and the outer member. A rolling device characterized in that the grease composition according to any one of claims 1 to 6 is filled in a gap formed between the outer member and the rolling element.

Images