WO2024101310A1 - Grease composition for rolling bearings, and rolling bearing - Google Patents

Grease composition for rolling bearings, and rolling bearing Download PDF

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WO2024101310A1
WO2024101310A1 PCT/JP2023/039898 JP2023039898W WO2024101310A1 WO 2024101310 A1 WO2024101310 A1 WO 2024101310A1 JP 2023039898 W JP2023039898 W JP 2023039898W WO 2024101310 A1 WO2024101310 A1 WO 2024101310A1
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mass
acid
grease composition
rust inhibitor
grease
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PCT/JP2023/039898
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French (fr)
Japanese (ja)
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和輝 宮内
大知 青木
昌俊 飯島
健太郎 園田
吉就 籠田
大貴 小松
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協同油脂株式会社
日本精工株式会社
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Publication of WO2024101310A1 publication Critical patent/WO2024101310A1/en

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  • the present invention relates to a grease composition for rolling bearings and a rolling bearing containing the grease composition.
  • the main spindle of a machine tool is preferably one that rotates at high speed to increase the processing efficiency, and various lubrication techniques are applied to its bearings.
  • lubrication methods suitable for a main spindle that rotates at high speed for example, oil mist lubrication, air oil lubrication, jet lubrication, etc. are known.
  • auxiliary equipment such as compressed air and oil supply devices, which is one of the causes of increasing the initial cost and running cost of the machine tool.
  • grease lubrication is a preferable lubrication method because it requires less maintenance.
  • Rolling bearings used in machine tools are often used in high speed rotation ranges exceeding dmn 800,000 (dmn: product of ball pitch circle diameter (mm) and rotation speed (min -1 )), and angular contact ball bearings or cylindrical roller bearings are used.
  • high preload is sometimes applied to increase the rigidity of the spindle, and the PV value of the rolling contact area of the inner and outer rings is often 100 MPa ⁇ m/s or more, so bearings for machine tools are required to have load-bearing performance under high-speed rotation conditions.
  • Patent Document 1 discloses a grease composition in which a urea compound as a thickener is blended in a base oil having a kinetic viscosity of 15 to 40 mm2/sec at 40°C in an amount of 9 to 14 mass% of the entire grease composition, resulting in a worked penetration of 220 to 320.
  • Patent Document 2 discloses a grease for high-speed bearings in which a urea grease using a urea compound as a thickener is blended with a non-urea grease using a complex amide lithium soap having an amide bond in the molecule as a thickener.
  • water-soluble coolant used during machining in machine tools can get into the bearings.
  • metal contact is more likely to occur, causing peeling and seizure, which will shorten the life of the bearing. It can also cause rust, leading to abnormal noise and accelerated bearing damage, making it necessary to replace the bearing in a short time.
  • Patent Document 3 proposes a method of adding a passivator to the grease composition
  • Patent Document 4 proposes a method of adding bismuth dithiocarbamate.
  • an object of the present invention is to provide a grease composition that addresses the same issues as those of rolling bearings for machine tools, and an object of the present invention is to provide a grease composition that is excellent in anti-seizure properties under high speed conditions, as well as excellent anti-flaking properties and anti-seizure properties when wet. Another object of the present invention is to provide a rolling bearing packed with the grease composition.
  • the following grease composition and a rolling bearing packed with the grease composition there is provided the following grease composition and a rolling bearing packed with the grease composition.
  • Base oil As a thickener, complex amide lithium soap,
  • As the antioxidant 0.5 to 5 mass% of an amine-based antioxidant and 0.5 to 5 mass% of a phenol-based antioxidant are used based on the total mass of the composition; and as the rust inhibitor, 0.1 to 5 mass% of a carboxylic acid-based rust inhibitor, 0.1 to 5 mass% of a carboxylate-based rust inhibitor, and 0.1 to 3 mass% of an amine salt of a fatty acid are used based on the total mass of the composition; Including, The 60-time worked penetration measured according to JIS K 2220 7. is 260 to 320.
  • the amine-based antioxidant is p,p-dioctyldiphenylamine, and the phenol-based antioxidant is benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester.
  • the grease composition according to 1 above wherein the carboxylic acid-based rust inhibitor is a combination of 2-tetrapropenyl succinic acid half ester and tetrapropenyl butanedioic acid, the carboxylate-based rust inhibitor is zinc naphthenate, and the amine-based rust inhibitor is a fatty acid amine salt. 5.
  • a bearing for machine tools in which the grease composition according to any one of 1 to 4 above is packed.
  • the present invention provides a grease composition and a bearing for machine tools that are excellent in seizure resistance under high speed conditions, as well as in peeling resistance and seizure resistance when wet.
  • the grease composition of the present invention also has excellent seizure resistance at high temperatures.
  • the type of base oil used in the present invention is not particularly limited.
  • various synthetic oils such as mineral oils such as naphthenic and paraffinic, synthetic hydrocarbon oils such as polyalphaolefins (PAO) and polybutene, synthetic ether oils such as alkyl diphenyl ether, ester oils, silicone oils, and fluorinated oils can be mentioned.
  • the synthetic oil may be a so-called biomass oil produced from biological resources derived from animals and plants.
  • biomass ester oils synthesized from various fatty acids and alcohols using vegetable oils as raw materials and biomass hydrocarbon oils using vegetable oils such as palm oil, corn oil, and soybean oil can also be used.
  • the base oil may be used alone or in a mixture of two or more kinds.
  • the kinetic viscosity of the base oil of the present invention at 40°C is preferably 10 mm2/s or more, more preferably 20 mm2/s or more, from the viewpoint of ensuring the oil film thickness of the base oil in the lubricated parts and improving durability by preventing metal contact, and is preferably 80 mm2 /s or less, more preferably 40 mm2/s or less, from the viewpoint of suppressing heat generation due to stirring.
  • the content of the base oil in the composition of the present invention is preferably 49 to 77 mass%, more preferably 56 to 74 mass%, and even more preferably 67 to 74 mass%, based on the total mass of the composition, taking into consideration adhesion and use in a high-speed environment.
  • the complex amide lithium soap which is the thickener of the present invention, is synthesized from an aliphatic dicarboxylic acid, an aliphatic monoamine, lithium hydroxide, etc.
  • a thickener containing a complex amide lithium soap i.e., a mixture of lithium N-octadecylsebacamate, lithium sebacic acid, and decanediamide dioctadecyl
  • lithium hydroxide i.e., a mixture of lithium N-octadecylsebacamate, lithium sebacic acid, and decanediamide dioctadecyl
  • N-octadecylsebacamic acid, sebacic acid, and decanediamide dioctadecyl which is a reaction product of an aliphatic dicarboxylic acid and an aliphatic monoamine, is particularly preferred.
  • the composition of the present invention preferably has a consistency of 260 to 300 so as to be suitable for use in high-speed environments such as machine tool bearings. This range is also suitable for use at high temperatures. 260 to 290 is more preferable.
  • the content of the thickener in the composition of the present invention may be any amount suitable for adjusting the consistency to the above range, and is, for example, 21.5 to 27 mass%, preferably 23 to 26 mass%, based on the total mass of the composition.
  • the term "consistency" refers to the 60-stroke worked consistency measured in accordance with JIS K 2220 7. From the viewpoint of oil supplying ability, it is preferable that the grease composition of the present invention does not contain a urea-based thickener.
  • the grease composition of the present invention contains 0.5 to 5 mass % of an amine-based antioxidant and 0.5 to 5 mass % of a phenol-based antioxidant based on the total mass of the composition.
  • the content of the amine-based antioxidant in the composition of the present invention is 0.5 to 5.0 mass%. At 0.5 mass% or more, a sufficient effect of preventing oxidative deterioration is exhibited, while at more than 5.0 mass%, the effect reaches a plateau. 0.5 to 3 mass% is preferable, and 0.8 to 2 mass% is more preferable.
  • the content of the phenolic antioxidant in the composition of the present invention is 0.5 to 5.0 mass%.
  • the content is preferably 1 to 3 mass%, and more preferably 1.5 to 2.5 mass%.
  • the amine-based antioxidant that can be used in the present invention is preferably selected from the group consisting of p,p'-dioctyldiphenylamine, N-phenyl- ⁇ -naphthylamine, alkylated phenyl- ⁇ -naphthylamine, and mixtures thereof, of which p,p'-dioctyldiphenylamine is particularly preferred.
  • the phenolic antioxidant that can be used in the present invention is preferably selected from the group consisting of 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and mixtures thereof.
  • benzenepropanoic acid 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester is particularly preferred.
  • a combination of p,p'-dioctyldiphenylamine and benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester is preferred.
  • a combination of 0.8 to 2 mass % of p,p'-dioctyldiphenylamine and 1.5 to 2.5 mass % of benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester is preferred.
  • the grease composition of the present invention contains, based on the total mass of the composition, 0.1 to 5 mass % of a carboxylic acid-based rust inhibitor, 0.1 to 5 mass % of a carboxylate-based rust inhibitor, and 0.1 to 3 mass % of an amine salt of a fatty acid.
  • the content of the carboxylic acid-based rust inhibitor in the composition of the present invention is 0.1 to 5 mass%. At 0.1 mass% or more, sufficient water resistance and rust prevention are exhibited, while at more than 5 mass%, the effect reaches a plateau. 0.2 to 3 mass% is preferable, and 0.2 to 1 mass% is more preferable.
  • the content of the carboxylate-based rust inhibitor in the composition of the present invention is 0.1 to 5 mass%. At 0.1 mass% or more, sufficient water resistance and rust prevention are exhibited, while at more than 5 mass%, the effect reaches a plateau. 0.2 to 3 mass% is preferable, and 0.2 to 1 mass% is more preferable.
  • the content of the fatty acid amine salt in the composition of the present invention is 0.1 to 3 mass%. At 0.1 mass% or more, water resistance and rust prevention are exhibited, while at more than 3 mass%, the effect plateaus. 0.3 to 2.5 mass% is preferable, and 0.5 to 2 mass% is more preferable.
  • carboxylic acid-based rust inhibitor examples include monocarboxylic acids such as straight-chain fatty acids such as lauric acid and stearic acid, and saturated carboxylic acids having a naphthenic nucleus; dicarboxylic acids such as succinic acid, alkyl succinic acids, alkyl succinic acid half esters, alkenyl succinic acids, alkenyl succinic acid half esters, and succinic acid imides; tetrapropenyl butanedioic acid, hydroxy fatty acids, mercapto fatty acids, and sarcosine derivatives.
  • monocarboxylic acids such as straight-chain fatty acids such as lauric acid and stearic acid, and saturated carboxylic acids having a naphthenic nucleus
  • dicarboxylic acids such as succinic acid, alkyl succinic acids, alkyl succinic acid half esters, alkenyl succinic acids, alkenyl succinic acid half
  • Carboxylate-based rust inhibitors that can be used in the present invention include metal salts of fatty acids, naphthenic acids, abietic acids, lanolin fatty acids, alkenyl succinic acids, amino acid derivatives, etc.
  • Metal elements include cobalt, manganese, zinc, aluminum, calcium, barium, lithium, magnesium, copper, etc., and zinc naphthenate is particularly preferred.
  • Examples of the amine salt of a fatty acid that can be used in the present invention include alkoxylphenylamines, amine salts of a fatty acid, and partial amides of dibasic carboxylic acids, with the amine salts of a fatty acid being preferred.
  • a combination of a carboxylic acid-based rust inhibitor containing an alkenyl succinic acid half ester, zinc naphthenate, and an amine salt of a fatty acid is preferred, and a combination of 2-tetrapropenyl succinic acid half ester, tetrapropenyl butanedioic acid, zinc naphthenate, and an amine salt of a fatty acid is even more preferred.
  • a combination of a carboxylic acid-based rust inhibitor containing 0.2 to 0.8 mass% of an alkenylsuccinic acid half ester, 0.2 to 0.8 mass% of zinc naphthenate, and 0.8 to 1.2 mass% of an amine salt of a fatty acid is preferred.
  • a combination of 0.1 to 0.4 mass% of 2-tetrapropenylsuccinic acid half ester, 0.1 to 0.4 mass% of tetrapropenylbutanedioic acid, 0.2 to 0.8 mass% of zinc naphthenate, and 0.8 to 1.2 mass% of an amine salt of a fatty acid is preferred.
  • the composition of the present invention includes
  • the base oil is a mixed oil having a mineral oil:PAO ratio of 35:65 to 45:55 and a kinematic viscosity at 40°C of 20 to 40 mm 2 /s;
  • the thickener is a complex amide lithium soap which is a reaction product of a mixture of N-octadecylsebacamic acid, sebacic acid, and dioctadecyl decanediamide with lithium hydroxide;
  • As antioxidants based on the total mass of the composition, 0.8 to 2 mass% of p,p'-dioctyldiphenylamine, and 1.5 to 2.5 mass% of benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester are included; and as rust inhibitors, based on the total mass of the composition, 0.1 to 0.4 mass% of 2-tetrapropenyl succ
  • the grease composition of the present invention may further contain additives that are commonly used in grease compositions, such as extreme pressure agents and waxes.
  • extreme pressure agents include phosphite esters of triphenyl phosphorothioate, triphenyl phosphite, triethyl phosphite, glycerol fatty acid esters such as glycerol monocaprate and glycerol monostearate.
  • the wax include monoamide wax, ester wax, ketone wax, and oxidized polyethylene wax.
  • the content of such optional additives is, for example, 0.1 to 5 mass %, preferably 0.3 to 3 mass %, based on the total mass of the composition.
  • the grease composition of the present invention is used for rolling bearings. It is particularly preferred to use it for rolling bearings of machine tool bearings, and even more particularly for the spindle support parts of rolling bearings of machine tools.
  • the grease composition can also be used for bearings that slide and rotate at high speeds, similar to machine tool bearings. It can also be used for bearings that slide and rotate at high speeds and high temperatures.
  • Examples 1 to 3 and Comparative Examples 2 to 5 A mixture of N-octadecylsebacamic acid, sebacic acid, and dioctadecyl decanediamide was reacted with lithium hydroxide in a base oil, and the mixture was heated and cooled to obtain a base grease. Additional base oil was added so as to obtain the 60-times worked penetration shown in Table 1, and each additive was added in the ratio shown in Table 1, and the mixture was dispersed using a three-roll mill to obtain the grease compositions of Examples 1 to 3 and Comparative Examples 2 to 5. The blending ratios and types of each component are as shown in Table 1.
  • Comparative Example 1 A grease composition of Comparative Example 1 was obtained in the same manner as above, except that a base grease containing lithium 12-hydroxystearate as the base oil was used.
  • Adhesion evaluation test evaluation of seizure resistance under high speed conditions
  • a tablet of test grease 4 is placed on the SPCC-SB steel plate shown in FIG. 1, and the steel plate is rotated under the conditions described below, and the amount of grease remaining after the test (g) is measured.
  • ⁇ Rotation speed 1000 rpm
  • Test time 3 min
  • Remaining grease amount is less than 0.045g
  • Oil supply test evaluation of seizure resistance
  • a tablet of grease is placed on a round 5C filter paper and left to stand in an air-circulating thermostatic chamber at 40°C for 168 hours.
  • the oil supply rate is calculated from the change in weight of the filter paper before and after the test using the following formula.
  • Oil supply amount % (amount of oil seeped into the filter paper after the test (g)/amount of grease before the test (g)) ⁇ 100 ⁇ Evaluation>
  • Oil supply rate is 30% or more and less than 50%
  • Oil supply rate is less than 30% or 50% or more
  • Centrifugal oil separation test evaluation of seizure resistance under high speed conditions
  • Grease 4 to be tested is placed in body 3 of test container 2, the inside of which is divided by mesh 1 (Fig. 2), and this test container 2 is connected to the tip of arm 5 of centrifugal oil separation tester 6 (Fig. 3), which has an arm 5 that rotates around rotation axis S, and the arm 5 is rotated under the conditions described below, causing centrifugal force to act on the grease in test container 2 as shown by the dotted line in Fig. 3.
  • the oil separation degree is calculated from the weight of the separated oil.
  • Oil separation rate % (amount of separated oil in g/amount of grease before test in g) x 100 ⁇ Evaluation> ⁇ : Oil separation rate is 15% or more and less than 30% ⁇ : Oil separation rate is less than 15% or 30% or more
  • Grease water absorption test evaluation of peeling resistance and seizure resistance when wet
  • the water absorption (%) is calculated according to the Defense Agency standard NDS K 2756B. ⁇ Evaluation> ⁇ : Water absorption rate less than 25% ⁇ : Water absorption rate 25% or more

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Abstract

The present invention provides a grease composition for rolling bearings, the grease composition containing: a base oil; a thickening agent that is composed of a composite amide lithium soap; an antioxidant that is composed of 0.5 to 5% by mass of an amine antioxidant and 0.5 to 5% by mass of phenol antioxidant based on the total mass of the composition; and a rust inhibitor that is composed of 0.1 to 5% by mass of a carboxylic acid rust inhibitor, 0.1 to 5% by mass of a carboxylate salt rust inhibitor and 0.1 to 3% by mass of an amine salt of a fatty acid based on the total mass of the composition. This grease composition for rolling bearings has a 60-stroke worked penetration of 260 to 320 as determined in accordance with JIS K 2220 7.

Description

転がり軸受用グリース組成物及び転がり軸受Grease composition for rolling bearings and rolling bearing
　本発明は、転がり軸受用グリース組成物及び前記グリース組成物を封入した転がり軸受に関する。 The present invention relates to a grease composition for rolling bearings and a rolling bearing containing the grease composition.
　工作機械の主軸は、加工能率を上げるために高速で回転するものが好ましく、その軸受には種々の潤滑技術が適用されている。高速回転する主軸に適した潤滑方法としては、例えば、オイルミスト潤滑、エアオイル潤滑、ジェット潤滑などの方法が知られている。しかし、このような潤滑方法は、圧縮空気や給油装置などの付帯設備が必要なものであり、工作機械のイニシャルコストおよびランニングコストを高める原因の一つとなる。これに対してグリース潤滑は、メンテナンスの必要が少なくて好ましい潤滑方法であるといえる。
　工作機械に用いられる転がり軸受は、ｄｍｎ８０万（ｄｍｎ：玉ピッチ円直径（ｍｍ）と回転数（ｍｉｎ-1）との積）を超えるような高速回転域で使用されることが多く、アンギュラ玉軸受や円筒ころ軸受が使用されている。
　また、工作機械では、主軸の剛性を高めるために高い予圧をかけることがあり、内輪や外輪の転がり接触部のＰＶ値が１００ＭＰａ・ｍ／ｓ以上になることが多く、工作機械用の軸受には高速回転条件下における耐荷重性能も求められる。更に、回転が高速化すると軸受の転がり面は高温になり、信頼性の低いグリースでは様々な外乱をきっかけに軸受の発熱増大と潤滑油膜の減少が連鎖することで焼付きが発生する。
　このような問題に対しては、耐熱性のある増ちょう剤や基油を使用したり、酸化防止剤を添加したりすることが行われている。例えば、耐熱性を考慮して、特許文献１では、４０°Ｃにおける動粘度が１５～４０ｍｍ2／ｓｅｃである基油に、増ちょう剤としてウレア化合物をグリース組成物全体の９～１４質量％となるように配合し、混和ちょう度が２２０～３２０であるグリース組成物が開示されている。また、特許文献２には、ウレア系化合物を増ちょう剤とするウレアグリースに、分子内にアミド結合を有する複合アミドリチウム石けんを増ちょう剤とする非ウレアグリースを配合した高速軸受用グリースが開示されている。
　また、工作機械では加工時に使用する水溶性のクーラントが軸受内部に侵入することがある。潤滑部の油膜へ水粒子が混入することで金属接触が発生しやすくなり、はく離や焼付きが起ることで軸受が寿命に至る。また、錆発生の原因となり異音や軸受の破損が早まり、短時間で軸受の交換が必要となる。
　このような早期に発生する特異的なはく離や焼付きを抑制する方法として、例えば、特許文献３には、グリース組成物に不動態化剤を添加する方法や、特許文献４にはビスマスジチオカーバメートを添加する方法が提案されている。 The main spindle of a machine tool is preferably one that rotates at high speed to increase the processing efficiency, and various lubrication techniques are applied to its bearings. As lubrication methods suitable for a main spindle that rotates at high speed, for example, oil mist lubrication, air oil lubrication, jet lubrication, etc. are known. However, such lubrication methods require auxiliary equipment such as compressed air and oil supply devices, which is one of the causes of increasing the initial cost and running cost of the machine tool. In contrast, grease lubrication is a preferable lubrication method because it requires less maintenance.
Rolling bearings used in machine tools are often used in high speed rotation ranges exceeding dmn 800,000 (dmn: product of ball pitch circle diameter (mm) and rotation speed (min -1 )), and angular contact ball bearings or cylindrical roller bearings are used.
In addition, in machine tools, high preload is sometimes applied to increase the rigidity of the spindle, and the PV value of the rolling contact area of the inner and outer rings is often 100 MPa·m/s or more, so bearings for machine tools are required to have load-bearing performance under high-speed rotation conditions. Furthermore, as the rotation speed increases, the rolling surface of the bearing becomes hotter, and with unreliable grease, various disturbances can trigger a chain reaction of increased heat generation in the bearing and a decrease in the lubricating oil film, causing seizure.
To address such problems, heat-resistant thickeners and base oils have been used, and antioxidants have been added. For example, in consideration of heat resistance, Patent Document 1 discloses a grease composition in which a urea compound as a thickener is blended in a base oil having a kinetic viscosity of 15 to 40 mm2/sec at 40°C in an amount of 9 to 14 mass% of the entire grease composition, resulting in a worked penetration of 220 to 320. Patent Document 2 discloses a grease for high-speed bearings in which a urea grease using a urea compound as a thickener is blended with a non-urea grease using a complex amide lithium soap having an amide bond in the molecule as a thickener.
In addition, water-soluble coolant used during machining in machine tools can get into the bearings. When water particles get mixed into the oil film in the lubricating part, metal contact is more likely to occur, causing peeling and seizure, which will shorten the life of the bearing. It can also cause rust, leading to abnormal noise and accelerated bearing damage, making it necessary to replace the bearing in a short time.
As methods for suppressing such specific early-stage peeling and seizure, for example, Patent Document 3 proposes a method of adding a passivator to the grease composition, and Patent Document 4 proposes a method of adding bismuth dithiocarbamate.
特開２００６－２９４７３号公報JP 2006-29473 A 特開２００９－２７５１７６号公報JP 2009-275176 A 特開平３－２１０３９４号公報Japanese Patent Application Laid-Open No. 3-210394 特開２００５－４２１０２号公報JP 2005-42102 A
　しかしながら、近年、コンパクト化や高速化に伴い運転条件や転がり軸受の使用状態がさらに過酷になり、ｄｍｎ値が１７０万以上という高速回転で使用される工作機械主軸用の転がり軸受なども多くなってきている。それに伴い、転がり面での発熱増加により、グリース熱劣化が促進されグリース寿命の著しい低下や、転動体が転走面を通過する回数が増えるため、クーラント混入時に早期にはく離や焼付きが発生し、寿命に至る可能性が高い。このような回転速度の高速化に伴って、潤滑性や高温耐久性に優れる等、高速回転にも十分に対応しつつ、クーラント混入時の金属接触による転走面でのはく離及び焼付き防止や錆の発生による軸受の破損防止を可能にする工作機械用転がり軸受が望まれている。
　かかる事情の下、本発明は、工作機械用転がり軸受と同様の課題に対処するグリース組成物を提供することを課題とし、高速条件での耐焼付き性に優れるとともに、含水時の耐はく離性及び耐焼付き性にも優れるグリース組成物を提供することを目的とする。本発明はまた、前記グリース組成物を封入した転がり軸受を提供することを目的とする。 However, in recent years, with the compactification and high speed, the operating conditions and the usage conditions of rolling bearings have become even harsher, and the number of rolling bearings for machine tool spindles used at high speed rotation with a dmn value of 1.7 million or more has increased. As a result, the increase in heat generation on the rolling surface promotes grease thermal degradation, significantly shortening the grease life, and the number of times the rolling body passes the rolling surface increases, so there is a high possibility that early flaking and seizure will occur when coolant is mixed in, and the bearing will reach the end of its life. With such high rotational speeds, there is a demand for rolling bearings for machine tools that are excellent in lubricity and high-temperature durability, and can fully handle high-speed rotation, while preventing flaking and seizure on the rolling surface due to metal contact when coolant is mixed in, and preventing damage to the bearing due to rust generation.
Under these circumstances, an object of the present invention is to provide a grease composition that addresses the same issues as those of rolling bearings for machine tools, and an object of the present invention is to provide a grease composition that is excellent in anti-seizure properties under high speed conditions, as well as excellent anti-flaking properties and anti-seizure properties when wet. Another object of the present invention is to provide a rolling bearing packed with the grease composition.
　本発明により、以下のグリース組成物及び前記グリース組成物を封入した転がり軸受を提供する。
１．基油、
　増ちょう剤として、複合アミドリチウム石けん、
　酸化防止剤として、組成物の全質量を基準として、アミン系酸化防止剤を０．５～５質量％、フェノール系酸化防止剤を０．５～５質量％、及び
　防錆剤として、組成物の全質量を基準として、カルボン酸系防錆剤を０．１～５質量％、カルボン酸塩系防錆剤を０．１～５質量％、脂肪酸のアミン塩を０．１～３質量％、
を含み、
　ＪＩＳ　Ｋ　２２２０　７．にしたがって測定される６０回混和ちょう度が２６０～３２０である、
転がり軸受用グリース組成物。
２．前記増ちょう剤が、Ｎアルキル置換モノアミド酸のリチウム塩と、二塩基酸のリチウム塩と、Ｎアルキル置換ジアミドとの混合物である、前記１に記載のグリース組成物。
３．前記アミン系酸化防止剤がｐ，ｐ－ジオクチルジフェニルアミンであり、及び前記フェノール系酸化防止剤がベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステルである、前記１に記載のグリース組成物。
４．前記カルボン酸系防錆剤が２－テトラプロぺニルコハク酸ハーフエステル及びテトラプロぺニルブタン二酸の組合せであり、カルボン酸塩系防錆剤がナフテン酸亜鉛であり、及びアミン系防錆剤が脂肪酸アミン塩である、前記１に記載のグリース組成物。
５．前記１～４のいずれかに記載のグリース組成物を封入してなる工作機械用軸受。 According to the present invention, there is provided the following grease composition and a rolling bearing packed with the grease composition.
1. Base oil,
As a thickener, complex amide lithium soap,
As the antioxidant, 0.5 to 5 mass% of an amine-based antioxidant and 0.5 to 5 mass% of a phenol-based antioxidant are used based on the total mass of the composition; and as the rust inhibitor, 0.1 to 5 mass% of a carboxylic acid-based rust inhibitor, 0.1 to 5 mass% of a carboxylate-based rust inhibitor, and 0.1 to 3 mass% of an amine salt of a fatty acid are used based on the total mass of the composition;
Including,
The 60-time worked penetration measured according to JIS K 2220 7. is 260 to 320.
A grease composition for rolling bearings.
2. The grease composition according to 1 above, wherein the thickener is a mixture of a lithium salt of an N-alkyl-substituted monoamidic acid, a lithium salt of a dibasic acid, and an N-alkyl-substituted diamide.
3. The grease composition according to 1 above, wherein the amine-based antioxidant is p,p-dioctyldiphenylamine, and the phenol-based antioxidant is benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester.
4. The grease composition according to 1 above, wherein the carboxylic acid-based rust inhibitor is a combination of 2-tetrapropenyl succinic acid half ester and tetrapropenyl butanedioic acid, the carboxylate-based rust inhibitor is zinc naphthenate, and the amine-based rust inhibitor is a fatty acid amine salt.
5. A bearing for machine tools, in which the grease composition according to any one of 1 to 4 above is packed.
　本発明により、高速条件での耐焼付き性並びに含水時の耐はく離性及び耐焼付き性に優れるグリース組成物及び工作機械用軸受を提供することができる。本発明のグリース組成物はまた、高温下での耐焼付き性にも優れる。 The present invention provides a grease composition and a bearing for machine tools that are excellent in seizure resistance under high speed conditions, as well as in peeling resistance and seizure resistance when wet. The grease composition of the present invention also has excellent seizure resistance at high temperatures.
付着性評価試験の概略図Schematic diagram of adhesion evaluation test 遠心離油度試験において用いた試験容器Test vessel used in centrifugal oil separation test 遠心離油度試験において用いた試験機Testing machine used in the centrifugal oil separation test
＜基油＞
　本発明で用いる基油の種類は特に制限されない。例えば、ナフテン系、パラフィン系に代表される鉱油、ポリαオレフィン（ＰＡＯ）、ポリブテンに代表される合成炭化水素油、アルキルジフェニルエーテルに代表されるエーテル系合成油、エステル油、シリコーン油、フッ素化油などの各種合成油が挙げられる。合成油は、動植物などから生まれた生物資源を原料として製造される、所謂バイオマス油でもよい。例えば、植物油を原料とする各種脂肪酸とアルコールとから合成されるバイオマスエステル油や、パーム油、コーン油、大豆油などの植物油を用いたバイオマス炭化水素油を使用することもできる。基油は、単独で用いてもよいし、２種以上を混合してもよい。このうち、鉱油及び合成炭化水素油が好ましく、鉱油と合成炭化水素油との混合油がより好ましく、鉱油とＰＡＯとの混合油がさらに好ましい。
　本発明の基油の４０℃における動粘度は、潤滑部において基油の油膜厚さが確保でき、金属接触を防止することで耐久性向上を図る観点から、１０ｍｍ2／ｓ以上であるのが好ましく、２０ｍｍ2／ｓ以上であるのがより好ましい。撹拌による発熱抑制の観点から、８０ｍｍ2／ｓ以下であるのが好ましく、４０ｍｍ2／ｓ以下であるのがより好ましい。
　本発明の基油が鉱油とＰＡＯとの混合油の場合、鉱油：ＰＡＯとが、質量比にして、鉱油：ＰＡＯ＝３０：７０～５０：５０であるのが油分供給性や基油の酸化劣化の観点から好ましく、３５：６５～４５：５５であるのがより好ましい。
　本発明の組成物中の基油の含有量は、付着性と高速環境下での使用を考慮し、組成物の全質量を基準にして、好ましくは４９～７７質量％、より好ましくは５６～７４質量％、さらに好ましくは６７～７４質量％である。このような範囲で基油を含ませることにより、潤滑部にグリースが留まり、高速運転時の漏れも抑制できるため、焼付き寿命の向上が期待できる。 <Base oil>
The type of base oil used in the present invention is not particularly limited. For example, various synthetic oils such as mineral oils such as naphthenic and paraffinic, synthetic hydrocarbon oils such as polyalphaolefins (PAO) and polybutene, synthetic ether oils such as alkyl diphenyl ether, ester oils, silicone oils, and fluorinated oils can be mentioned. The synthetic oil may be a so-called biomass oil produced from biological resources derived from animals and plants. For example, biomass ester oils synthesized from various fatty acids and alcohols using vegetable oils as raw materials, and biomass hydrocarbon oils using vegetable oils such as palm oil, corn oil, and soybean oil can also be used. The base oil may be used alone or in a mixture of two or more kinds. Among them, mineral oils and synthetic hydrocarbon oils are preferred, a mixed oil of mineral oil and synthetic hydrocarbon oil is more preferred, and a mixed oil of mineral oil and PAO is even more preferred.
The kinetic viscosity of the base oil of the present invention at 40°C is preferably 10 mm2/s or more, more preferably 20 mm2/s or more, from the viewpoint of ensuring the oil film thickness of the base oil in the lubricated parts and improving durability by preventing metal contact, and is preferably 80 mm2 /s or less, more preferably 40 mm2/s or less, from the viewpoint of suppressing heat generation due to stirring.
When the base oil of the present invention is a mixed oil of mineral oil and PAO, the mass ratio of mineral oil:PAO is preferably mineral oil:PAO=30:70 to 50:50 from the viewpoints of oil supplyability and oxidative deterioration of the base oil, and more preferably 35:65 to 45:55.
The content of the base oil in the composition of the present invention is preferably 49 to 77 mass%, more preferably 56 to 74 mass%, and even more preferably 67 to 74 mass%, based on the total mass of the composition, taking into consideration adhesion and use in a high-speed environment. By including the base oil in such a range, the grease remains in the lubricated parts and leakage during high-speed operation can be suppressed, so that an improvement in seizure life can be expected.
＜増ちょう剤＞
　本発明の増ちょう剤である複合アミドリチウム石けんは、脂肪族ジカルボン酸、脂肪族モノアミン、水酸化リチウムなどから合成される。脂肪族ジカルボン酸と脂肪族モノアミンとの反応物である、Ｎ－オクタデシルセバカミン酸と、セバシン酸と、デカンジアミドジオクタデシルとの混合物に、さらに水酸化リチウムを作用させて得られる複合アミドリチウム石けん（すなわち、Ｎ－オクタデシルセバカミン酸リチウムと、セバシン酸リチウムと、デカンジアミドジオクタデシルとの混合物）を含む増ちょう剤が特に好ましい。
　本発明の組成物は、工作機械用軸受などの、高速環境下での使用に適するよう、ちょう度を２６０～３００とするのが好ましい。この範囲は、高温での使用にも適する。２６０～２９０がより好ましい。本発明の組成物中の増ちょう剤の含有量は、ちょう度を上記範囲に調整するのに適した量であればよく、組成物の全質量を基準として、例えば２１．５～２７質量％、好ましくは２３～２６質量％である。なお、本明細書において、単に「ちょう度」と称する場合、ＪＩＳ　Ｋ　２２２０　７．にしたがって測定される６０回混和ちょう度を指す。
　油分供給性の観点から、本発明のグリース組成物は、ウレア系増ちょう剤を含まないのが好ましい。 <Thickener>
The complex amide lithium soap, which is the thickener of the present invention, is synthesized from an aliphatic dicarboxylic acid, an aliphatic monoamine, lithium hydroxide, etc. A thickener containing a complex amide lithium soap (i.e., a mixture of lithium N-octadecylsebacamate, lithium sebacic acid, and decanediamide dioctadecyl) obtained by further reacting lithium hydroxide with a mixture of N-octadecylsebacamic acid, sebacic acid, and decanediamide dioctadecyl, which is a reaction product of an aliphatic dicarboxylic acid and an aliphatic monoamine, is particularly preferred.
The composition of the present invention preferably has a consistency of 260 to 300 so as to be suitable for use in high-speed environments such as machine tool bearings. This range is also suitable for use at high temperatures. 260 to 290 is more preferable. The content of the thickener in the composition of the present invention may be any amount suitable for adjusting the consistency to the above range, and is, for example, 21.5 to 27 mass%, preferably 23 to 26 mass%, based on the total mass of the composition. In this specification, the term "consistency" refers to the 60-stroke worked consistency measured in accordance with JIS K 2220 7.
From the viewpoint of oil supplying ability, it is preferable that the grease composition of the present invention does not contain a urea-based thickener.
＜酸化防止剤＞
　本発明のグリース組成物は、組成物の全質量を基準として、アミン系酸化防止剤を０．５～５質量％、フェノール系酸化防止剤を０．５～５質量％含有する。
　本発明の組成物中のアミン系酸化防止剤の含有量は、０．５～５．０質量％である。０．５質量以上で十分な酸化劣化防止効果を示し、他方、５．０質量％を超えても効果は頭打ちとなる。０．５～３質量％が好ましく、０．８～２質量％がより好ましい。
　本発明の組成物中のフェノール系酸化防止剤の含有量は、０．５～５．０質量％である。０．５質量以上で十分な酸化劣化防止を示し、他方、５．０質量％を超えても効果は頭打ちとなる。１～３質量％が好ましく、１．５～２．５質量％がより好ましい。
　本発明において用いることができるアミン系酸化防止剤としては、ｐ，ｐ’－ジオクチルジフェニルアミン、Ｎ－フェニル－α－ナフチルアミン、アルキル化フェニル－α－ナフチルアミン及びこれらの混合物からなる群から選ばれるのが好ましい。このうち、ｐ，ｐ’－ジオクチルジフェニルアミンが特に好ましい。
　本発明において用いることができるフェノール系酸化防止剤としては、２，６－ジ－ｔｅｒｔ－ブチル－４－メチルフェノール、ペンタエリスリトールテトラキス（３－（３，５－ジ－ｔｅｒｔ－ブチル－４－ヒドロキシフェニル）プロピオネート）、ベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステル、オクタデシル－３－（３，５－ジ－ｔ－ブチル－４－ヒドロキシフェニル）プロピオネート及びこれらの混合物からなる群から選ばれるのが好ましい。このうち、ベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステルが特に好ましい。
　特に、グリースの酸化劣化抑制の観点から、ｐ，ｐ’－ジオクチルジフェニルアミンとベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステルとの組合せが好ましい。
　とりわけ、０．８～２質量％のｐ，ｐ’－ジオクチルジフェニルアミンと１．５～２．５質量％のベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステルとの組合せが好ましい。 <Antioxidants>
The grease composition of the present invention contains 0.5 to 5 mass % of an amine-based antioxidant and 0.5 to 5 mass % of a phenol-based antioxidant based on the total mass of the composition.
The content of the amine-based antioxidant in the composition of the present invention is 0.5 to 5.0 mass%. At 0.5 mass% or more, a sufficient effect of preventing oxidative deterioration is exhibited, while at more than 5.0 mass%, the effect reaches a plateau. 0.5 to 3 mass% is preferable, and 0.8 to 2 mass% is more preferable.
The content of the phenolic antioxidant in the composition of the present invention is 0.5 to 5.0 mass%. At 0.5 mass% or more, sufficient prevention of oxidative deterioration is exhibited, while at more than 5.0 mass%, the effect reaches a plateau. The content is preferably 1 to 3 mass%, and more preferably 1.5 to 2.5 mass%.
The amine-based antioxidant that can be used in the present invention is preferably selected from the group consisting of p,p'-dioctyldiphenylamine, N-phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, and mixtures thereof, of which p,p'-dioctyldiphenylamine is particularly preferred.
The phenolic antioxidant that can be used in the present invention is preferably selected from the group consisting of 2,6-di-tert-butyl-4-methylphenol, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester, octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and mixtures thereof. Of these, benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester is particularly preferred.
In particular, from the viewpoint of inhibiting oxidative deterioration of the grease, a combination of p,p'-dioctyldiphenylamine and benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester is preferred.
In particular, a combination of 0.8 to 2 mass % of p,p'-dioctyldiphenylamine and 1.5 to 2.5 mass % of benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester is preferred.
＜防錆剤＞
　本発明のグリース組成物は、組成物の全質量を基準として、カルボン酸系防錆剤を０．１～５質量％、カルボン酸塩系防錆剤を０．１～５質量％、脂肪酸のアミン塩を０．１～３質量％含有する。
　本発明の組成物中のカルボン酸系防錆剤の含有量は、０．１～５質量％である。０．１質量以上で十分な耐水性及び防錆性を示し、他方、５質量％を超えても効果は頭打ちとなる。０．２～３質量％が好ましく、０．２～１質量％がより好ましい。
　本発明の組成物中のカルボン酸塩系防錆剤の含有量は、０．１～５質量％である。０．１質量以上で十分な耐水性及び防錆性を示し、他方、５質量％を超えても効果は頭打ちとなる。０．２～３質量％が好ましく、０．２～１質量％がより好ましい。
　本発明の組成物中の脂肪酸のアミン塩の含有量は、０．１～３質量％である。０．１質量以上で耐水性及び防錆性を示し、他方、３質量％を超えても効果は頭打ちとなる。０．３～２．５質量％が好ましく、０．５～２質量％がより好ましい。 <Rust inhibitor>
The grease composition of the present invention contains, based on the total mass of the composition, 0.1 to 5 mass % of a carboxylic acid-based rust inhibitor, 0.1 to 5 mass % of a carboxylate-based rust inhibitor, and 0.1 to 3 mass % of an amine salt of a fatty acid.
The content of the carboxylic acid-based rust inhibitor in the composition of the present invention is 0.1 to 5 mass%. At 0.1 mass% or more, sufficient water resistance and rust prevention are exhibited, while at more than 5 mass%, the effect reaches a plateau. 0.2 to 3 mass% is preferable, and 0.2 to 1 mass% is more preferable.
The content of the carboxylate-based rust inhibitor in the composition of the present invention is 0.1 to 5 mass%. At 0.1 mass% or more, sufficient water resistance and rust prevention are exhibited, while at more than 5 mass%, the effect reaches a plateau. 0.2 to 3 mass% is preferable, and 0.2 to 1 mass% is more preferable.
The content of the fatty acid amine salt in the composition of the present invention is 0.1 to 3 mass%. At 0.1 mass% or more, water resistance and rust prevention are exhibited, while at more than 3 mass%, the effect plateaus. 0.3 to 2.5 mass% is preferable, and 0.5 to 2 mass% is more preferable.
　本発明において用いることができるカルボン酸系防錆剤としては、モノカルボン酸として、例えば、ラウリン酸、ステアリン酸などの直鎖脂肪酸、ナフテン核を有する飽和カルボン酸；ジカルボン酸として、例えば、コハク酸、アルキルコハク酸、アルキルコハク酸ハーフエステル、アルケニルコハク酸、アルケニルコハク酸ハーフエステル、コハク酸イミドなどのコハク酸誘導体、テトラプロペニルブタン二酸、ヒドロキシ脂肪酸、メルカプト脂肪酸、ザルコシン誘導体を挙げることができる。なかでも２－テトラプロぺニルコハク酸ハーフエステル及びテトラプロペニルブタン二酸が好適である。
　本発明において用いることができるカルボン酸塩系防錆剤としては、脂肪酸、ナフテン酸、アビエンチ酸、ラノリン脂肪酸、アルケニルコハク酸、アミノ酸誘導体などの金属塩などが挙げられる。また、金属元素としては、コバルト、マンガン、亜鉛、アルミニウム、カルシウム、バリウム、リチウム、マグネシウム、銅などが挙げられるが、なかでもナフテン酸亜鉛が好適である。
　本発明において用いることができる脂肪酸のアミン塩としては、アルコキシルフェニルアミン、脂肪酸のアミン塩、二塩基性カルボン酸の部分アミドなどを挙げることができるが、脂肪酸のアミン塩が好適である。
　特に、油膜への水混入抑制の観点から、アルケニルコハク酸ハーフエステルを含むカルボン酸系防錆剤と、ナフテン酸亜鉛と、脂肪酸のアミン塩との組合せが好ましい。さらに特に、２－テトラプロぺニルコハク酸ハーフエステルと、テトラプロぺニルブタン二酸と、ナフテン酸亜鉛と、脂肪酸のアミン塩との組合せが好ましい。
　とりわけ、０．２～０．８質量％のアルケニルコハク酸ハーフエステルを含むカルボン酸系防錆剤と、０．２～０．８質量％のナフテン酸亜鉛と、０．８～１．２質量％の脂肪酸のアミン塩との組合せが好ましい。さらに特に２－テトラプロぺニルコハク酸ハーフエステルが０．１～０．４質量％と、テトラプロぺニルブタン二酸が０．１～０．４と、ナフテン酸亜鉛が０．２～０．８質量％と、０．８～１．２質量％の脂肪酸のアミン塩である組合せが好ましい。 Examples of the carboxylic acid-based rust inhibitor that can be used in the present invention include monocarboxylic acids such as straight-chain fatty acids such as lauric acid and stearic acid, and saturated carboxylic acids having a naphthenic nucleus; dicarboxylic acids such as succinic acid, alkyl succinic acids, alkyl succinic acid half esters, alkenyl succinic acids, alkenyl succinic acid half esters, and succinic acid imides; tetrapropenyl butanedioic acid, hydroxy fatty acids, mercapto fatty acids, and sarcosine derivatives. Among these, 2-tetrapropenyl succinic acid half ester and tetrapropenyl butanedioic acid are preferred.
Carboxylate-based rust inhibitors that can be used in the present invention include metal salts of fatty acids, naphthenic acids, abietic acids, lanolin fatty acids, alkenyl succinic acids, amino acid derivatives, etc. Metal elements include cobalt, manganese, zinc, aluminum, calcium, barium, lithium, magnesium, copper, etc., and zinc naphthenate is particularly preferred.
Examples of the amine salt of a fatty acid that can be used in the present invention include alkoxylphenylamines, amine salts of a fatty acid, and partial amides of dibasic carboxylic acids, with the amine salts of a fatty acid being preferred.
In particular, from the viewpoint of suppressing water contamination of the oil film, a combination of a carboxylic acid-based rust inhibitor containing an alkenyl succinic acid half ester, zinc naphthenate, and an amine salt of a fatty acid is preferred, and a combination of 2-tetrapropenyl succinic acid half ester, tetrapropenyl butanedioic acid, zinc naphthenate, and an amine salt of a fatty acid is even more preferred.
In particular, a combination of a carboxylic acid-based rust inhibitor containing 0.2 to 0.8 mass% of an alkenylsuccinic acid half ester, 0.2 to 0.8 mass% of zinc naphthenate, and 0.8 to 1.2 mass% of an amine salt of a fatty acid is preferred.More particularly, a combination of 0.1 to 0.4 mass% of 2-tetrapropenylsuccinic acid half ester, 0.1 to 0.4 mass% of tetrapropenylbutanedioic acid, 0.2 to 0.8 mass% of zinc naphthenate, and 0.8 to 1.2 mass% of an amine salt of a fatty acid is preferred.
　本発明の組成物としては、
　基油が、鉱油：ＰＡＯ＝３５：６５～４５：５５である、４０℃における動粘度が２０～４０ｍｍ2/ｓである混合油であり、
　増ちょう剤が、Ｎ－オクタデシルセバカミン酸と、セバシン酸と、デカンジアミドジオクタデシルの混合物と、水酸化リチウムとの反応物である複合アミドリチウム石けんであり、
　酸化防止剤として、組成物の全質量を基準として、ｐ，ｐ’－ジオクチルジフェニルアミンを０．８～２質量％、ベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステルを１．５～２．５質量％、及び
　防錆剤として、組成物の全質量を基準として、２－テトラプロぺニルコハク酸ハーフエステルを０．１～０．４質量％と、テトラプロぺニルブタン二酸を０．１～０．４質量％と、ナフテン酸亜鉛を０．２～０．８質量％と、脂肪酸のアミン塩を０．８～１．２質量％、
を含み、
　ＪＩＳ　Ｋ　２２２０　７．にしたがって測定される６０回混和ちょう度が２６０～２９０である工作機械軸受用グリース組成物、
がとりわけ好ましい。 The composition of the present invention includes
The base oil is a mixed oil having a mineral oil:PAO ratio of 35:65 to 45:55 and a kinematic viscosity at 40°C of 20 to 40 mm 2 /s;
The thickener is a complex amide lithium soap which is a reaction product of a mixture of N-octadecylsebacamic acid, sebacic acid, and dioctadecyl decanediamide with lithium hydroxide;
As antioxidants, based on the total mass of the composition, 0.8 to 2 mass% of p,p'-dioctyldiphenylamine, and 1.5 to 2.5 mass% of benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester are included; and as rust inhibitors, based on the total mass of the composition, 0.1 to 0.4 mass% of 2-tetrapropenyl succinic acid half ester, 0.1 to 0.4 mass% of tetrapropenyl butanedioic acid, 0.2 to 0.8 mass% of zinc naphthenate, and 0.8 to 1.2 mass% of an amine salt of a fatty acid are included;
Including,
A grease composition for machine tool bearings having a 60-stroke worked penetration of 260 to 290 as measured in accordance with JIS K 2220 7.
is particularly preferred.
　本発明のグリース組成物には、上記成分に加えて、更に、グリース組成物に通常使用される添加剤を含ませることができる。このような任意の添加剤としては、例えば、極圧剤、ワックスがあげられる。
　極圧剤としては、トリフェニルホスホロチオエート、トリフェニルホスファイト、トリエチルホスファイトの亜リン酸エステル、モノカプリン酸グリセロール、モノステアリン酸グリセロールのグリセリン脂肪酸エステル等があげられる。
　ワックスとしては、モノアミドワックス、エステルワックス、ケトンワックス、酸化ポリエチレンワックス等があげられる。
　このような任意の添加剤の含有量は、組成物の全質量を基準にして、例えば、０．１～５質量％、好ましくは０．３～３質量％である。 In addition to the above-mentioned components, the grease composition of the present invention may further contain additives that are commonly used in grease compositions, such as extreme pressure agents and waxes.
Examples of extreme pressure agents include phosphite esters of triphenyl phosphorothioate, triphenyl phosphite, triethyl phosphite, glycerol fatty acid esters such as glycerol monocaprate and glycerol monostearate.
Examples of the wax include monoamide wax, ester wax, ketone wax, and oxidized polyethylene wax.
The content of such optional additives is, for example, 0.1 to 5 mass %, preferably 0.3 to 3 mass %, based on the total mass of the composition.
　本発明のグリース組成物は転がり軸受に用いる。特に、工作機械軸受の転がり軸受、さらに特に、工作機械の転がり軸受の主軸支持部に用いるのが好ましい。工作機械軸受以外にも、工作機械軸受と同様、高速で摺動、回転する軸受にも適用することができる。高速かつ高温下で摺動、回転する軸受にも適用することができる。 The grease composition of the present invention is used for rolling bearings. It is particularly preferred to use it for rolling bearings of machine tool bearings, and even more particularly for the spindle support parts of rolling bearings of machine tools. In addition to machine tool bearings, the grease composition can also be used for bearings that slide and rotate at high speeds, similar to machine tool bearings. It can also be used for bearings that slide and rotate at high speeds and high temperatures.
＜実施例１～３及び比較例２～５＞
　基油中で、Ｎ－オクタデシルセバカミン酸と、セバシン酸と、デカンジアミドジオクタデシルの混合物と、水酸化リチウムとを反応させ、加温冷却し、ベースグリースを得た。表１に示す６０回混和ちょう度になるように追加の基油を添加し、表１に示す割合で各添加剤を添加し、３本ロールミルで分散することにより、実施例１～３及び比較例２～５のグリース組成物を得た。それぞれの配合割合及び種類は表１のとおりである。なお、表中の各成分についての数字は、鉱油とＰＡＯが質量比を示し、動粘度の単位がｍｍ2/ｓである他は、組成物の全質量を基準とした質量％である。
＜比較例１＞
　基油に１２ヒドロキシステアリン酸リチウムを含むベースグリースを用いて上と同様の手順にて比較例１のグリース組成物を得た。 <Examples 1 to 3 and Comparative Examples 2 to 5>
A mixture of N-octadecylsebacamic acid, sebacic acid, and dioctadecyl decanediamide was reacted with lithium hydroxide in a base oil, and the mixture was heated and cooled to obtain a base grease. Additional base oil was added so as to obtain the 60-times worked penetration shown in Table 1, and each additive was added in the ratio shown in Table 1, and the mixture was dispersed using a three-roll mill to obtain the grease compositions of Examples 1 to 3 and Comparative Examples 2 to 5. The blending ratios and types of each component are as shown in Table 1. The numbers for each component in the table indicate the mass ratio of mineral oil and PAO, and the units of kinematic viscosity are mm2 /s, but the rest are mass % based on the total mass of the composition.
<Comparative Example 1>
A grease composition of Comparative Example 1 was obtained in the same manner as above, except that a base grease containing lithium 12-hydroxystearate as the base oil was used.
　得られた実施例及び比較例のグリース組成物を、以下の試験方法及び試験条件により評価した。
１．熱硬化試験（高温下での耐焼付き性の評価）
　６０×８０×１ｍｍのＳＰＣＣ－ＳＤ鋼板に、試験グリースを２ｍｍの厚さで均一に塗布し、１６０℃の空気循環式恒温槽中で３００時間静置し、試験後のちょう度を測定する。
　＜評価＞
　　○：ちょう度１５０以上
　　×：ちょう度１５０未満 The obtained grease compositions of the Examples and Comparative Examples were evaluated by the following test methods and test conditions.
1. Heat curing test (evaluation of seizure resistance under high temperatures)
The test grease is applied evenly to a thickness of 2 mm on a 60 x 80 x 1 mm SPCC-SD steel plate, and left to stand in an air-circulating thermostatic chamber at 160°C for 300 hours, after which the consistency is measured.
<Evaluation>
○: Consistency 150 or more ×: Consistency less than 150
２．付着性評価試験（高速条件での耐焼付き性の評価）
　図１に示すＳＰＣＣ－ＳＢ鋼板上に、タブレット状にした試験グリース４を乗せ、下記条件で鋼板を回転させ、試験後のグリース残存量（ｇ）を測定する。
・回転数：１０００ｒｐｍ
・試験時間：３ｍｉｎ
・温度：２５℃
　＜評価＞
　　○：グリース残存量０.０４５ｇ以上
　　×：グリース残存量０.０４５ｇ未満 2. Adhesion evaluation test (evaluation of seizure resistance under high speed conditions)
A tablet of test grease 4 is placed on the SPCC-SB steel plate shown in FIG. 1, and the steel plate is rotated under the conditions described below, and the amount of grease remaining after the test (g) is measured.
・Rotation speed: 1000 rpm
Test time: 3 min
Temperature: 25°C
<Evaluation>
○: Remaining grease amount is 0.045g or more ×: Remaining grease amount is less than 0.045g
３．油分供給性試験（耐焼付き性の評価）
　丸形の５Ｃろ紙上に、タブレット状にしたグリースを乗せ、４０℃の空気循環式恒温槽中で１６８時間静置し、試験前後のろ紙の重量変化から、下記式により油分供給率を算出する。
油分供給量％＝（試験後にろ紙に染み出した油分量ｇ／試験前のグリース量ｇ）×１００
　＜評価＞
　　○：油分供給率が３０％以上５０％未満
　　×：油分供給率が３０％未満または５０％以上 3. Oil supply test (evaluation of seizure resistance)
A tablet of grease is placed on a round 5C filter paper and left to stand in an air-circulating thermostatic chamber at 40°C for 168 hours. The oil supply rate is calculated from the change in weight of the filter paper before and after the test using the following formula.
Oil supply amount %=(amount of oil seeped into the filter paper after the test (g)/amount of grease before the test (g))×100
<Evaluation>
○: Oil supply rate is 30% or more and less than 50% ×: Oil supply rate is less than 30% or 50% or more
４．遠心離油度試験（高速条件での耐焼付き性の評価）
　内部がメッシュ１で区切られた試験容器２の本体３内に試験対象のグリース４を収容し（図２）、この試験容器２を、回転軸Ｓを中心に回転するアーム５を備えた遠心離油度試験機６（図３）のアーム５の先端に連結し、下記条件にてアーム５を回転させ、図３に点線で示すように試験容器２内のグリースに遠心力を作用させる。試験終了後に分離した油分重量から離油度を算出する。
・試験時間：１６８時間
・回転速度：２０００ｒｐｍ
・温度：４０℃
・メッシュ１と回転軸Ｓの中心との距離Ｌ：４６．５ｍｍ
　　離油度％＝（分離した油分量ｇ／試験前のグリース量ｇ）×１００
　＜評価＞
　　○：離油度が１５％以上３０％未満
　　×：離油度が１５％未満または３０％以上 4. Centrifugal oil separation test (evaluation of seizure resistance under high speed conditions)
Grease 4 to be tested is placed in body 3 of test container 2, the inside of which is divided by mesh 1 (Fig. 2), and this test container 2 is connected to the tip of arm 5 of centrifugal oil separation tester 6 (Fig. 3), which has an arm 5 that rotates around rotation axis S, and the arm 5 is rotated under the conditions described below, causing centrifugal force to act on the grease in test container 2 as shown by the dotted line in Fig. 3. After the test is completed, the oil separation degree is calculated from the weight of the separated oil.
Test time: 168 hours Rotation speed: 2000 rpm
Temperature: 40°C
Distance L between mesh 1 and the center of rotation axis S: 46.5 mm
Oil separation rate % = (amount of separated oil in g/amount of grease before test in g) x 100
<Evaluation>
○: Oil separation rate is 15% or more and less than 30% ×: Oil separation rate is less than 15% or 30% or more
５．グリース吸水度試験（含水時の耐はく離性及び耐焼付き性の評価）
　防衛庁規格ＮＤＳ　Ｋ　２７５６Ｂにより測定される吸水度（％）を算出する。
　＜評価＞
　　○：吸水度２５％未満
　　×：吸水度２５％以上 5. Grease water absorption test (evaluation of peeling resistance and seizure resistance when wet)
The water absorption (%) is calculated according to the Defense Agency standard NDS K 2756B.
<Evaluation>
○: Water absorption rate less than 25% ×: Water absorption rate 25% or more
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001

Claims (5)

  1. 　基油、
    　増ちょう剤として、複合アミドリチウム石けん、
    　酸化防止剤として、組成物の全質量を基準として、アミン系酸化防止剤を０．５～５質量％、フェノール系酸化防止剤を０．５～５質量％、及び
    　防錆剤として、組成物の全質量を基準として、カルボン酸系防錆剤を０．１～５質量％、カルボン酸塩系防錆剤を０．１～５質量％、脂肪酸のアミン塩を０．１～３質量％、
    を含み、
    　ＪＩＳ　Ｋ　２２２０　７．にしたがって測定される６０回混和ちょう度が２６０～３２０である、
    転がり軸受用グリース組成物。     Base oil,
    As a thickener, complex amide lithium soap,
    As the antioxidant, 0.5 to 5 mass% of an amine-based antioxidant and 0.5 to 5 mass% of a phenol-based antioxidant are used based on the total mass of the composition; and as the rust inhibitor, 0.1 to 5 mass% of a carboxylic acid-based rust inhibitor, 0.1 to 5 mass% of a carboxylate-based rust inhibitor, and 0.1 to 3 mass% of an amine salt of a fatty acid are used based on the total mass of the composition;
    Including,
    The 60-time worked penetration measured according to JIS K 2220 7. is 260 to 320.
    A grease composition for rolling bearings.
  2. 　前記増ちょう剤が、Ｎアルキル置換モノアミド酸のリチウム塩と、二塩基酸のリチウム塩と、Ｎアルキル置換ジアミドとの混合物である、請求項１に記載のグリース組成物。 The grease composition according to claim 1, wherein the thickener is a mixture of a lithium salt of an N-alkyl-substituted monoamido acid, a lithium salt of a dibasic acid, and an N-alkyl-substituted diamide.
  3. 　前記アミン系酸化防止剤がｐ，ｐ－ジオクチルジフェニルアミンであり、及び前記フェノール系酸化防止剤がベンゼンプロパン酸，３，５－ビス（１，１－ジメチル－エチル）－４－ヒドロキシＣ７－Ｃ９側鎖アルキルエステルである、請求項１に記載のグリース組成物。 The grease composition according to claim 1, wherein the amine-based antioxidant is p,p-dioctyldiphenylamine, and the phenol-based antioxidant is benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy C7-C9 side chain alkyl ester.
  4. 　前記カルボン酸系防錆剤が２－テトラプロぺニルコハク酸ハーフエステル及びテトラプロぺニルブタン二酸の組合せであり、カルボン酸塩系防錆剤がナフテン酸亜鉛であり、及びアミン系防錆剤が脂肪酸アミン塩である、請求項１に記載のグリース組成物。 The grease composition according to claim 1, wherein the carboxylic acid-based rust inhibitor is a combination of 2-tetrapropenyl succinic acid half ester and tetrapropenyl butanedioic acid, the carboxylate-based rust inhibitor is zinc naphthenate, and the amine-based rust inhibitor is a fatty acid amine salt.
  5. 　請求項１～４のいずれか１項記載のグリース組成物を封入してなる工作機械用軸受。 　A bearing for machine tools containing the grease composition according to any one of claims 1 to 4.
PCT/JP2023/039898 2022-11-07 2023-11-06 Grease composition for rolling bearings, and rolling bearing WO2024101310A1 (en)

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4911607B1 (en) * 1970-10-31 1974-03-18
JPS63108098A (en) * 1986-10-24 1988-05-12 Kyodo Yushi Kk Heavy load resistant grease composition
JPH0218497A (en) * 1988-07-07 1990-01-22 Kyodo Yushi Kk High-load-resistant grease composition
JP2009209990A (en) * 2008-03-03 2009-09-17 Ntn Corp Grease filled bearing for motor
WO2009139371A1 (en) * 2008-05-16 2009-11-19 Ntn株式会社 Grease for high-speed bearing
JP2010024440A (en) * 2008-06-16 2010-02-04 Kyodo Yushi Co Ltd Grease composition
JP2010043183A (en) * 2008-08-12 2010-02-25 Ntn Corp Grease for universal joint and universal joint
WO2010027019A1 (en) * 2008-09-05 2010-03-11 Ntn株式会社 Grease composition, and roller bearing and universal joint packed with said grease composition
WO2011046079A1 (en) * 2009-10-13 2011-04-21 Ｎｏｋクリューバー株式会社 Lubricating grease composition for reciprocating sliding, and manufacturing method therefor
JP2014108999A (en) * 2012-12-03 2014-06-12 Kyodo Yushi Co Ltd Grease composition for main electric motor shaft bearing of railway vehicle, and shaft bearing

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4911607B1 (en) * 1970-10-31 1974-03-18
JPS63108098A (en) * 1986-10-24 1988-05-12 Kyodo Yushi Kk Heavy load resistant grease composition
JPH0218497A (en) * 1988-07-07 1990-01-22 Kyodo Yushi Kk High-load-resistant grease composition
JP2009209990A (en) * 2008-03-03 2009-09-17 Ntn Corp Grease filled bearing for motor
WO2009139371A1 (en) * 2008-05-16 2009-11-19 Ntn株式会社 Grease for high-speed bearing
JP2010024440A (en) * 2008-06-16 2010-02-04 Kyodo Yushi Co Ltd Grease composition
JP2010043183A (en) * 2008-08-12 2010-02-25 Ntn Corp Grease for universal joint and universal joint
WO2010027019A1 (en) * 2008-09-05 2010-03-11 Ntn株式会社 Grease composition, and roller bearing and universal joint packed with said grease composition
WO2011046079A1 (en) * 2009-10-13 2011-04-21 Ｎｏｋクリューバー株式会社 Lubricating grease composition for reciprocating sliding, and manufacturing method therefor
JP2014108999A (en) * 2012-12-03 2014-06-12 Kyodo Yushi Co Ltd Grease composition for main electric motor shaft bearing of railway vehicle, and shaft bearing

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