JP6978357B2 - Grease composition and rolling bearings - Google Patents

Description

The present invention relates to grease compositions and rolling bearings.

There are various ways to extend the seizure life of rolling bearings. For example, by adding a very small amount of superbasic Ca sulfonate to a grease containing a diurea compound as a thickener, the produced oxidative deterioration products can be captured even under severe conditions such as high temperature and high speed for a long period of time, and the grease can be used. There is known a grease composition capable of suppressing curing and continuously flowing grease into the lubricating portion to extend the seizure life of the rolling bearing (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2010-77320

An object of the present invention is to provide a grease composition and a rolling bearing capable of further extending the seizure life of the rolling bearing.

As a result of diligent studies to solve the above problems, the present inventors have used a specific alicyclic aliphatic diurea as a thickener, and set the amount of the thickener and the hyperbasic Ca sulfonate in a specific range. The present invention was completed by finding that the seizure life of the rolling bearing can be further extended by controlling the rolling bearing.
That is, the present invention includes the following aspects.
[1] A grease composition for rolling bearings containing a base oil, a thickener and an additive.
The thickener is based on the following formula:
R ^1- NHCONH-R ^2- NHCONH-R ¹ (1);
R ^1- NHCONH-R ^2- NHCONH-R ³ (2); and R ^3- NHCONH-R ^2- NHCONH-R ³ (3);
(In the formula, R ¹ represents a C _10-26 alkyl group, R ² represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ³ represents a C _5-7 cycloalkyl group. show)
It is a mixture of diurea compounds represented by
The content of the thickener is 13.0-19.0% by mass with respect to the total amount of the grease composition.
The additive contains a hyperbasic Ca sulfonate and
The grease composition for rolling bearings, wherein the content of the hyperbasic Ca sulfonate is 0.5% by mass or more and less than 1.5% by mass with respect to the total amount of the grease composition.
[2] ratio of the number of moles of R ³ to the total number of moles of R ¹ and R ³ is 20 to 50 mol%, [1] the rolling bearing grease composition.
[3] The grease composition for rolling bearings according to [1] or [2], wherein the base value of the hyperbasic Ca sulfonate is 50 to 500 mgKOH / g.
[4] A rolling bearing in which the grease composition for a rolling bearing according to any one of [1] to [3] is sealed.

According to the present invention, it is possible to provide a grease composition and a rolling bearing that can further extend the seizure life of a rolling bearing. Further, according to the present invention, it is possible to provide a grease composition for a rolling bearing and a rolling bearing which are further excellent in acoustic performance.

<Grease composition for rolling bearings>
The grease composition for rolling bearings of the present invention contains a base oil, a thickener and an additive. Hereinafter, each component will be described.
(1) Base oil As the base oil, all base oils including mineral oil can be used. In addition, ester-based synthetic oils typified by diesters and polyol esters (eg, trimethylolpropane ester, pentaerythritol ester, dipentaerythritol ester); alkyl diphenyl ethers, ether-based synthetic oils typified by polypropylene glycol; polyα-olefins, Synthetic hydrocarbon oils typified by polybutene; silicone oils; synthetic oils such as fluorine oil can be used. These may be used alone or as a mixed oil of two or more kinds.
When only one type of base oil is used, mineral oil, poly-α-olefin, and ester oil are preferable, and poly-α-olefin and ester oil (for example, pentaerythritol ester and dipentaerythritol ester) are more preferable.
When the base oil is used as a mixed oil of two or more kinds, a combination of mineral oil and synthetic oil is preferable, a combination of mineral oil and synthetic hydrocarbon oil is more preferable, and a combination of mineral oil and poly-α-olefin is most preferable.
In the combination of mineral oil and synthetic oil, the synthetic oil is preferably 5% by mass or more (for example, 5 to 50% by mass), more preferably 10% by mass or more (for example, 15 to 45% by mass), and more preferably 20% by mass or more (for example). 25-40% by mass) is most preferable.
The kinematic viscosity of the base oil at 40 ° C. is not particularly limited, but is, for example, 20 to 100 mm ² / s, preferably 25 to 80 mm ² / s, more preferably 30 to 60 mm ² / s, and particularly preferably 30 to 50 mm. ^{It is 2} / s. The kinematic viscosity at 40 ° C. is measured by a method according to JIS K 2283.
The base oil is the balance excluding the thickener and the additive, and the content of the base oil depends on the content of the thickener and the additive, but is, for example, 74 with respect to the total amount of the grease composition. It is ~ 86.95% by mass, preferably 75 to 85% by mass (for example, 80 to 85% by mass).

Ｒ³の具体例としては、シクロペンチル、シクロヘキシル、シクロヘプチルなどが挙げられる。これらのうち、シクロヘキシルが好ましい。
Ｒ¹とＲ³の総モル数に対するＲ³のモル数の割合は、例えば、１０〜９０モル％の範囲から選択でき、２０〜５０モル％であるのが好ましく、２０〜４０モル％（例えば、２０〜３０モル％）であるのがより好ましい。
増ちょう剤は、炭素数１０〜２６のアルキルアミンと、炭素数５〜７のシクロアルキルアミンと、炭素数６〜１５の芳香族ジイソシアネートとの反応により得られる。
前記アルキルアミンとしては、例えば、デシルアミン、ドデシルアミン、テトラデシルアミン、ヘキサデシルアミン、オクタデシルアミン（ステアリルアミン）、これらの組み合わせなどが挙げられる。
前記シクロアルキルアミンとしては、例えば、シクロペンチルアミン、シクロヘキシルアミン、シクロヘプチルアミン、これらの組み合わせなどが挙げられる。
前記アルキルアミンと前記シクロアルキルアミンとのモル比は、特に制限はないが、例えば、１：９〜９：１の範囲から選択でき、５：５〜８：２であるのが好ましく、６：４〜８：２（例えば、７：３〜８：２）であるのがより好ましい。
前記芳香族ジイソシアネートとしては、例えば、キシリレンジイソシアネート、トリレンジイソシアネート、ナフタレンジイソシアネート、ジフェニルメタン−４，４’−ジイソシアネート、トリジンジイソシアネート、これらの組み合わせなどが挙げられる。
前記芳香族ジイソシアネートの使用量は、前記脂肪族モノアミン及び前記脂環族モノアミンの総量に対し、０．５モル当量又はそれ以下であってもよい。
上記反応は、溶媒の存在下、１０〜１５０℃で行ってもよい。溶媒としては、揮発性の溶媒を使用してもよいが、基油を使用するとそのまま本発明のベースグリースとなる。
増ちょう剤の含有量は、グリース組成物の総量に対して、１３．０〜１９．０質量％の範囲から選択でき、１３．５〜１８．０質量％であるのが好ましく、１５．０〜１８．０質量％であるのがより好ましい。 (2) Thickener The thickener is the following formula:
R ^1- NHCONH-R ^2- NHCONH-R ¹ (1);
R ^1- NHCONH-R ^2- NHCONH-R ³ (2); and R ^3- NHCONH-R ^2- NHCONH-R ³ (3);
(In the formula, R ¹ represents a C _10-26 alkyl group, R ² represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ³ represents a C _5-7 cycloalkyl group. show)
It is a mixture of diurea compounds represented by.
Specific examples of R ¹ include decyl, dodecyl, tetradecyl, hexadecyl, octadecyl (stearyl), and icocil. Of these, octadecyl is preferred.
Specific examples of R ² include phenylene, naphthylene, diphenylmethanediyl, biphenylene (these groups may be substituted with an alkyl group having 1 to 4 carbon atoms such as methyl) and the like. Of these, the groups represented by the formulas (A) to (C) are preferable, and the groups represented by the formula (B) are more preferable.

Specific examples of R ³ include cyclopentyl, cyclohexyl, cycloheptyl and the like. Of these, cyclohexyl is preferred.
Moles ratio of R ³ to the total number of moles of R ¹ and R ³ are, for example, be selected from the range of 10 to 90 mol%, preferably from 20 to 50 mol%, 20 to 40 mol% (e.g. 20 to 30 mol%) is more preferable.
The thickener is obtained by reacting an alkylamine having 10 to 26 carbon atoms, a cycloalkylamine having 5 to 7 carbon atoms, and an aromatic diisocyanate having 6 to 15 carbon atoms.
Examples of the alkylamine include decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine (stearylamine), and combinations thereof.
Examples of the cycloalkylamine include cyclopentylamine, cyclohexylamine, cycloheptylamine, and combinations thereof.
The molar ratio of the alkylamine to the cycloalkylamine is not particularly limited, but can be selected from, for example, in the range of 1: 9 to 9: 1, preferably 5: 5 to 8: 2, and 6: It is more preferably 4 to 8: 2 (for example, 7: 3 to 8: 2).
Examples of the aromatic diisocyanate include xylylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, diphenylmethane-4,4'-diisocyanate, trizine diisocyanate, and combinations thereof.
The amount of the aromatic diisocyanate used may be 0.5 molar equivalent or less with respect to the total amount of the aliphatic monoamine and the alicyclic monoamine.
The above reaction may be carried out at 10 to 150 ° C. in the presence of a solvent. A volatile solvent may be used as the solvent, but if a base oil is used, the base grease of the present invention can be used as it is.
The content of the thickener can be selected from the range of 13.0 to 19.0% by mass with respect to the total amount of the grease composition, and is preferably 13.5 to 18.0% by mass, preferably 15.0. It is more preferably ~ 18.0% by mass.

(3) Additives Additives contain hyperbasic Ca sulfonate.
Examples of the hyperbasic Ca sulfonate include a hyperbasic calcium salt of an alkyl aromatic sulfonic acid, a hyperbasic calcium salt of petroleum sulfonic acid, a superbasic calcium salt of an oxide wax, and a combination thereof. Of these, hyperbasic calcium salts of alkyl aromatic sulfonic acids are preferred.
The base value of the hyperbasic Ca sulfonate is not particularly limited as long as it is superbasic, and the base value measured according to JIS K 2501 is, for example, 50 to 500 mgKOH / g, preferably 350 to 450 mgKOH. / G (eg, 375-405 mgKOH / g). The hyperbasic Ca sulfonate may be used in combination with a Ca sulfonate other than the hyperbasic Ca sulfonate (for example, a neutral Ca sulfonate).
The content of the superbasic Ca sulfonate can be selected from the range of 0.5% by mass or more and less than 1.5% by mass (for example, 0.5 to 1.2% by mass) with respect to the total amount of the grease composition. It is preferably 0.8 to 1.2% by mass, and more preferably 0.9 to 1.1% by mass (for example, 1 to 1.1% by mass). In the present invention, even if the content of the hyperbasic Ca sulfonate is in the above range, the seizure life of the rolling bearing can be extended.
The grease composition for rolling bearings of the present invention may further contain other additives. The other additives are not particularly limited as long as the effects of the present invention are not impaired, and are, for example, solid lubricants, antioxidants, rust inhibitors, metal corrosion inhibitors, oily agents, abrasion resistant agents, extreme pressure agents and the like. Can be mentioned.
Examples of the solid lubricant include molybdenum disulfide, graphite, polytetrafluoroethylene (PTFE), melamine cyanurate (MCA) and the like.
As antioxidants, amine-based (for example, diphenylamine, phenylα-naphthylamine, alkylated products thereof) and phenol-based (for example, 2,6-di-t-butyl-p-cresol, pentaerythritol-tetrakis) [3-( 3,5-Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and other hindered phenols), quinoline-based (eg, , 2, 2, 4-trimethyl-1,2 dihydroquinoline polymer) and the like.
Examples of the rust preventive include carboxylic acid-based [for example, lower fatty acids such as alkenyl succinic acid, higher fatty acids such as naphthenic acid and lanolin fatty acid, and salts thereof (alkali metal salts such as Na salt; alkaline soil such as Ca salt and Mg salt). Metal salts; Al salts; Zn salts; amine salts, etc.), anhydrides, esters], sulfonic acid-based [for example, sulfonates (alkali metal salts such as Na salt; alkaline earth metal salts such as Ba salt; Zn). Salt, etc.)].
Examples of the metal corrosion inhibitor include benzotriazole and the like.
Examples of the oily agent include fatty acids, fatty acid esters, and phosphoric acid esters.
Examples of the abrasion resistant agent or extreme pressure agent include phosphorus-based (for example, tricresyl phosphate, tri-2-ethylhexyl phosphate), sulfur-based (for example, dibenzyldisulfide, various polysulfides), and sulfur-phosphorus-based (for example, tri). Phenylphosphorothionate), organic metal-based [for example, metal salts of dialkyldithiophosphate (Zn salt, Mo salt, Sb salt, Bi salt, etc.), metal salts of dialkyldithiocarbamic acid (Zn salt, Mo salt, Sb salt, etc.), Ni salt, Cu salt, Bi salt, etc.)].
These other additives may be used alone or in combination of two or more. Of these other additives, antioxidants, rust inhibitors and metal corrosion inhibitors are preferred.
The content of the other additives is, for example, 10% by mass or less, preferably 8% by mass or less (for example, 0.05 to 6% by mass) with respect to the total amount of the grease composition. When two or more kinds of other additives are used, the content of each additive is, for example, 0.05 to 3% by mass, more preferably 0.5 to 2.5% by mass, based on the total amount of the grease composition. %.

The consistency of the grease composition for rolling bearings is not particularly limited, but the consistency can be selected from, for example, 180 to 280, preferably 185 to 270, and more preferably 200 to 270. .. The consistency is a value measured immediately after the sample is mixed 60 times back and forth with a specified mixer as defined in JIS K 2220.

で表されるジウレア化合物の混合物（又はオクタデシルアミンとシクロヘキシルアミンと４，４−ジフェニルメタンジイソシアネートとの反応生成物）であり、
オクタデシル基とシクロヘキシル基の総モル数に対するシクロヘキシル基のモル数の割合が、２０〜５０モル％（又は前記反応生成物において、オクタデシルアミンとシクロヘキシルアミンのモル比が５：５〜８：２）であり、
前記増ちょう剤の含有量が、グリース組成物の総量に対して、１３．０〜１９．０質量％であり、
前記添加剤が、過塩基性Ｃａスルホネート（特に、アルキル芳香族スルホン酸の過塩基性カルシウム塩）を含んでおり、
前記過塩基性Ｃａスルホネートの塩基価が、３５０〜４５０ｍｇＫＯＨ／ｇであり、
前記過塩基性Ｃａスルホネートの含有量が、グリース組成物の総量に対して、０．５〜１．２質量％である、転がり軸受用グリース組成物である。 A preferred rolling bearing grease composition comprises a base oil, a thickener and an additive.
The base oil is either mineral oil alone or a combination of mineral oil and synthetic hydrocarbon oil (particularly a combination of mineral oil and synthetic hydrocarbon oil).
The kinematic viscosity of the base oil at 40 ° C. is 30 to 60 mm ² / s (particularly, 30 to 50 mm ² / s).
The thickener is based on the following formula:

It is a mixture of diurea compounds represented by (or a reaction product of octadecylamine, cyclohexylamine and 4,4-diphenylmethane diisocyanate).
The ratio of the number of moles of cyclohexyl group to the total number of moles of octadecyl group and cyclohexyl group is 20 to 50 mol% (or the molar ratio of octadecylamine to cyclohexylamine in the reaction product is 5: 5 to 8: 2). can be,
The content of the thickener is 13.0-19.0% by mass with respect to the total amount of the grease composition.
The additive comprises a hyperbasic Ca sulfonate, in particular a hyperbasic calcium salt of an alkyl aromatic sulfonic acid.
The base value of the hyperbasic Ca sulfonate is 350 to 450 mgKOH / g, and the base value is 350 to 450 mgKOH / g.
A grease composition for rolling bearings, wherein the content of the hyperbasic Ca sulfonate is 0.5 to 1.2% by mass with respect to the total amount of the grease composition.

<Rolling bearing>
The rolling bearing of the present invention contains the above grease composition. The rolling bearing may be, for example, a ball bearing (for example, a deep groove ball bearing, an angular ball bearing, a thrust ball bearing, etc.) or a roller bearing (for example, a cylindrical roller bearing, a conical roller bearing), depending on the type of rolling element. good.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

<Baking life test (based on ASTM D 3336)>
The bearing 6204 (deep groove ball bearing) is filled with 1.8 g of test grease, shield plates of steel plates are crimped on both sides, the outer ring temperature of the bearing is kept at 160 ° C., and under the condition of load Fa = Fr = 67N, 10 The inner ring is continuously operated at 000 rpm. The seizure life was defined as the time until the rotational torque of the bearing became excessive and an overcurrent (4 amperes) was generated, or the bearing temperature rose by 15 ° C. or more.

<Acoustic performance>
(Test method / conditions) Acoustic performance test using an Anderon meter Fill the bearing 608 with 0.35 ml of test grease, and rotate the inner ring at 1800 rpm under the condition of load Fa = 2 kgf. The sound generated from the bearing was measured with an Anderon meter.
Anderon value for 120 seconds is less than 3 Anderon: Pass (○)
Anderon value is 3 Anderon or more for 120 seconds: Fail (×)

<Preparation of test grease>
(1) Base oil The base oils used in Examples and Comparative Examples are as follows.
Mineral oil A (kinematic viscosity at 40 ° C: 46 mm ² / s)
Mineral oil B (kinematic viscosity at 40 ° C: 33.8 mm ² / s)
Poly-α-olefin (kinematic viscosity at 40 ° C: 48.5 mm ² / s)
Ester oil (kinematic viscosity at 40 ° C: 32.7 mm ² / s)
(2) Hyperbasic Ca sulfonate The hyperbasic Ca sulfonate used in Examples and Comparative Examples is as follows.
Hyperbasic Ca sulfonate A (perbasic calcium salt of alkyl aromatic sulfonic acid, base value: 375 mg / KOH)
Hyperbasic Ca sulfonate B (perbasic calcium salt of alkyl aromatic sulfonic acid, base value: 405 mg / KOH)
(3) Examples 1-10, Comparative Examples 1-7
In the base oils shown in Tables 1 to 3, a mixture of 4,4-diphenylmethane diisocyanate and an amine (molar ratio of cyclohexylamine to stearylamine = 3: 7) was reacted to obtain a base grease. A predetermined amount of superbasic Ca sulfonate was added to the base grease and mixed well. Finally, the grease composition was kneaded with a three-roll mill to produce a grease composition having a miscibility of 185 to 270.
(Comparative Example 8)
In the base oil shown in Table 4, 4,4-diphenylmethane diisocyanate and paratoluidine were reacted to obtain a base grease. A predetermined amount of superbasic Ca sulfonate was added to the base grease and mixed well. Finally, the grease composition was kneaded with a three-roll mill to produce a grease composition having a miscibility of 380.

<Test results>
The test results are shown in Tables 1 to 4.

The seizure life of the rolling bearing in which the grease composition of the example was sealed was significantly extended as compared with the seizure life of the rolling bearing in which the grease composition of the comparative example was sealed. In Comparative Example 8 in which the aromatic diurea was used, the grease softened and flowed out, and the baking life was shortened.
Moreover, the acoustic performance of the grease composition of the example is remarkably superior to the acoustic performance of Comparative Example 8 using the aromatic diurea.

Claims (4)

A grease composition for rolling bearings containing a base oil, a thickener and an additive.
The base oil is selected from the group consisting of mineral oil; ester-based synthetic oil selected from the group consisting of diester, pentaerythritol ester, and dipentaerythritol ester; ether-based synthetic oil; synthetic hydrocarbon oil; silicone oil and fluorine oil. At least one
The thickener is based on the following formula:
R ^1- NHCONH-R ^2- NHCONH-R ¹ (1);
R ^1- NHCONH-R ^2- NHCONH-R ³ (2); and R ^3- NHCONH-R ^2- NHCONH-R ³ (3);
(In the formula, R ¹ represents a C _10-26 alkyl group, R ² represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ³ represents a C _5-7 cycloalkyl group. show)
It is a mixture of diurea compounds represented by
The content of the thickener is 13.0-19.0% by mass with respect to the total amount of the grease composition.
The additive contains a hyperbasic Ca sulfonate and
The grease composition for rolling bearings, wherein the content of the hyperbasic Ca sulfonate is 0.5% by mass or more and less than 1.5% by mass with respect to the total amount of the grease composition. Moles ratio of R ³ to the total number of moles of R ¹ and R ³ is 20 to 50 mol%, claim 1 rolling bearing grease composition. The grease composition for rolling bearings according to claim 1 or 2, wherein the superbasic Ca sulfonate has a base value of 50 to 500 mgKOH / g. A rolling bearing in which the grease composition for a rolling bearing according to any one of claims 1 to 3 is sealed.