JP5227526B2 - Vehicle bearing lubricant - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is used for bearings of vehicles such as railways and automobiles, particularly for vehicles that run at high speeds and for vehicles that run in cold regions, and has excellent thermal and oxidation stability and good operation in cold regions. The present invention relates to a vehicle bearing lubricating oil that can exhibit excellent performance and has high reliability.

Conventionally, grease compositions are mainly used as lubricants for vehicle bearings of railways and the like. For example, Japanese Patent No. 3254484 (Patent Document 1) discloses an axle bearing for a high-speed railway vehicle in which a diurea compound having a specific structure is blended with a base oil having a kinematic viscosity at 40 ° C. of 50 to 180 mm ² / s. A grease composition is disclosed, and the grease composition exhibits excellent lubricity even under high speed conditions with a dN value of 100,000 or more, and has a sufficiently long bearing life. Japanese Patent No. 3508802 (Patent Document 2) discloses a grease comprising a base oil having a viscosity of 47 to 334 mm ² / s at 40 ° C., a urea compound, nickel dithiocarbamate or tellurium, It is said that the axle bearing of a railway vehicle in which the grease is sealed is superior in speed and long-term reliability than the conventional one.

Japanese Patent No. 3254484 Japanese Patent No. 3508802

  However, when grease is used as a lubricant for vehicle bearings, it is difficult to replace the lubricant when it deteriorates. Specifically, the replacement of the lubricant involves a very complicated operation of disassembling and taking out the bearing portion from the equipment and removing the deteriorated grease. In that respect, the liquid lubricating oil has the advantage of good maintainability and easy maintenance and management.

  The bearing lubricating oil is required to have improved durability from the viewpoints of reliability for further speeding-up of railway vehicles and energy savings. In particular, in order to cope with high-speed running and long-term use, that is, increase in oil temperature and long-term durability, further improvement in thermal and oxidation stability is strongly demanded for lubricating oil, and it is reliable to solve these problems. It leads to improvement of energy and energy saving. Furthermore, a lubricating oil having excellent low-temperature characteristics is required as a highly reliable lubricating oil even in a cold region.

  The present invention has been made in view of such circumstances, and an object of the present invention is to achieve both high thermal and oxidation stability and low temperature characteristics at a high level, and in various environments. An object of the present invention is to provide a vehicular bearing lubricant that exhibits excellent characteristics in high-speed driving of a vehicle.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above problem is achieved by a lubricating oil in which an olefin copolymer and an antioxidant are added to a base oil mainly composed of poly-α-olefin, which is a synthetic oil. Has been found to be solved, and the present invention has been completed.

That is, the vehicle bearing lubricating oil of the present invention has a base oil containing 50 to 100% by weight of poly-α-olefin having a kinematic viscosity of 15 to 60 mm ² / s at 40 ° C. and a kinematic viscosity (40 ° C.) of 300. It contains ^{2 to} 5% by weight of an olefin copolymer composed of an ethylene-propylene copolymer having a number average molecular weight of 1000 to 4000 at -40000 mm ² / s and 0.2 to 3% by weight of an amine-based antioxidant, and has a viscosity index of 140 is 160, the kinematic viscosity at 40 ° C. and pour point at 20 to 80 mm ² / s is characterized in that at -50 ° C. or less.

The vehicle bearing lubricating oil of the present invention, the base oil has a viscosity index in saturated components in the chromatographic analysis of 90% or more may comprise 0 to 50 wt% of more than 100 mineral base oil. Moreover, it is preferable that the vehicle bearing lubricating oil of the present invention further contains 0.5 to 5% by weight of an ester.

  According to the present invention, it is possible to provide an easily replaceable vehicle bearing lubricant that has excellent low temperature characteristics and excellent thermal and oxidation stability.

The present invention is described in detail below. In the vehicle bearing lubricating oil of the present invention, a hydrocarbon mainly composed of poly-α-olefin having a kinematic viscosity at 40 ° C. of 15 to 60 mm ² / s is used as the base oil. The poly-α-olefin is obtained by polymerizing an α-olefin having 8 to 20 carbon atoms, particularly 10 to 16 carbon atoms such as 1-decene, and its kinematic viscosity at 40 ° C. is preferably 25 to 60 mm ^2. / s, more preferably 30 to 60 mm ² / s, particularly preferably 30 to 50 mm ² / s. In addition, the content rate of the poly-alpha-olefin in a base oil is the range of 50-100 weight%.

  In the vehicle bearing lubricating oil of the present invention, a mineral base oil can be blended as another component of the above base oil, and the mineral oil base oil has a viscosity of 90% or more in the chromatographic analysis of ASTM D2007 and has a viscosity. It is preferable that the index is 100 or more and the viscosity index is 110 to 130. The mineral oil base oil preferably has a saturation content of 90 to 100%, more preferably 95 to 100%. In addition, the content ratio of the mineral oil base oil in the base oil is preferably in the range of 0 to 50% by weight.

  Specifically, as the mineral oil base oil, a fraction obtained by subjecting an atmospheric distillation residue such as paraffinic crude oil to vacuum distillation is subjected to solvent extraction by hydrocracking or furfural, hydrorefining, and MEK / toluene. By treating the lubricating base oil obtained by treating with a treatment method such as solvent dewaxing or hydrodewaxing, and the defoamed oil obtained by removing the residue of the vacuum distillation by the appropriate treatment method described above. Highly refined base oils obtained by hydroisomerizing the obtained lubricating base oil, slack wax, FT synthetic wax and the like and mixtures thereof can be used.

Olefin copolymers for use in the vehicle for bearing lubrication oil of the invention, ethylene - consists propylene copolymer, the ethylene - propylene copolymer, which has ethylene and propylene are copolymerized by such coordination anionic polymerization catalyst, the polymerization degree It is possible to adjust the viscosity. In the present invention, kinematic viscosity at 40 ° C. The number average molecular weight in 300~40000mm ² / s is ethylene 1000 to 4000 - using propylene copolymers.

The content of the olefin copolymer is in the range of 2 to 5% by weight. If the content of the olefin copolymer is less than 1% by weight, the viscosity index may not be sufficiently improved, while if it exceeds 10% by weight, the effect of improving the viscosity index is saturated.

In the vehicle bearing lubricating oil of the present invention, it is necessary to use an amine-based antioxidant as the antioxidant, and an ashless antioxidant such as a phenol-based antioxidant or a metal such as zinc dithiophosphate. The contained antioxidant can also be used . In the vehicle bearing lubricating oil of the present invention, the content of the amine-based antioxidant is 0.2 to 3% by weight. If the content of the amine antioxidant is less than 0.2% by weight, the oxidation stability is insufficient. On the other hand, if the content exceeds 3% by weight, a degradation product of the amine antioxidant itself tends to precipitate, There is a risk of sludge.

  Examples of the amine-based antioxidant compound include diphenylamine derivatives, phenyl-α-naphthylamine derivatives and the like, and compounds represented by the following general formula (1) and compounds represented by the following general formula (2) are preferable. A compound represented by the following general formula (2) is particularly preferred.

上記式（１）の化合物は、一般的には、Ｎ-フェニルベンゼンアミンとアルケンとを反応させて得られる。式（１）において、Ｒ¹は、水素または炭化水素基であり、ｎ及びｍはそれぞれ独立して０〜５の整数である。なお、Ｒ¹が複数存在する場合、各Ｒ¹は、同一であっても異なっていてもよい。ここで、炭化水素基の炭素数は、１以上１２以下が好ましく、１以上９以下が特に好ましい。また、炭化水素基としては、アルキル基が特に好ましい。

The compound of the above formula (1) is generally obtained by reacting N-phenylbenzenamine with an alkene. In Formula (1), R ¹ is hydrogen or a hydrocarbon group, and n and m are each independently an integer of 0 to 5. When a plurality of R ¹ are present, each R ¹ may be the same or different. Here, the carbon number of the hydrocarbon group is preferably 1 or more and 12 or less, particularly preferably 1 or more and 9 or less. Further, as the hydrocarbon group, an alkyl group is particularly preferable.

上記式（２）において、Ｒ²は炭素数が３以上２０以下の炭化水素基であり、ｐは０〜５の整数で、ｑは０〜７の整数であり、但し、ｐ及びｑの両方が０であることはない。なお、Ｒ²が複数存在する場合、各Ｒ²は、同一であっても異なっていてもよい。また、Ｒ²としては、直鎖又は分枝鎖のオクチル基ないしノニル基が特に好ましく、また、ナフチル基及びフェニル基のどちらか一方が１個のＲ²で置換されているものが特に好ましい。

In the above formula (2), R ² is a hydrocarbon group having 3 to 20 carbon atoms, p is an integer of 0 to 5, and q is an integer of 0 to 7, provided that both p and q are Is never zero. When a plurality of R ² are present, each R ² may be the same or different. R ² is particularly preferably a linear or branched octyl group or nonyl group, and one in which either a naphthyl group or a phenyl group is substituted with one R ² is particularly preferable.

  The phenolic antioxidant is 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 4,4′-methylenebis (2,6-di-t-butylphenol). ) 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -t-butylphenol), 4,4'-isopropylidenebisphenol, 2,4-dimethyl-6-t-butylphenol, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Methane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-) t-butyl-4-hydroxybenzyl) benzene, 2,6-di-t-butyl-4-ethylphen Nord, 2,6-bis (2′-hydroxy-3′-t-butyl-5′-methylbenzyl) -4-methylphenol, bis [2- (2-hydroxy-5-methyl-3-t-butyl) Benzyl) -4-methyl-6-t-butylphenyl] terephthalate, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol- And bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]. In particular, a phenolic antioxidant containing an ester group is preferred.

  The vehicle bearing lubricating oil of the present invention preferably further contains an ester. As the ester, monoesters, diesters, polyol esters and the like can be used, and among these, saturated diesters and polyol esters are preferable. The diester is synthesized from a divalent carboxylic acid and a monohydric alcohol, and examples thereof include an adipic acid ester. The carbon number of the alcohol is preferably 6 to 20, and may be linear or branched.

  The polyol ester is synthesized from a polyhydric alcohol such as neopentyl glycol, trimethylolpropane, pentaerythritol and a monovalent carboxylic acid, and the monovalent carboxylic acid preferably has 5 to 20 carbon atoms. good.

  The amount of the ester added is preferably in the range of 0.5 to 5% by weight, and more preferably in the range of 1 to 5% by weight. By adding 0.5% by weight or more of ester, the rubber material used for the seal is slightly swollen and leakage of the lubricating oil can be prevented. On the other hand, when it exceeds 5% by weight, the rubber material is excessively swollen and the sealing material is weakened.

  In order to further improve various performances of the vehicle bearing lubricating oil of the present invention, known additives such as rust preventive agents, antiwear agents, extreme pressure agents, oiliness agents, antifoaming agents, metal deactivators, etc. Can be appropriately blended.

The nature of the vehicle bearing lubricating oil of the present invention, kinematic viscosity at 40 ° C. was 20 to 80 mm ² / s, preferably 40~70mm ² / s. If the kinematic viscosity at 40 ° C. of the vehicle bearing lubricant is less than 20 mm ² / s, sufficient lubricity cannot be ensured and the bearing may be abnormally worn. On the other hand, if it exceeds 80 mm ² / s, the viscosity resistance is too large and energy saving cannot be achieved. The vehicular bearing lubricant of the present invention preferably has a kinematic viscosity at 100 ° C. of 4 to 12 mm ² / s, and more preferably 6 to 10.5 mm ² / s. Furthermore, the vehicle bearing lubricating oil of the invention has a viscosity index of 140 to 160. Furthermore, the vehicular bearing lubricant of the present invention has a pour point of −50 ° C. or lower. When the pour point of the vehicle bearing lubricant exceeds -30 ° C, the low temperature characteristics are deteriorated, and the reliability in use in cold regions in winter is lowered.

  The vehicle bearing lubricant of the present invention described in detail above is used as a lubricant for bearings in vehicles such as railways and automobiles. Further, the vehicle bearing lubricant of the present invention is excellent in thermal / oxidative stability and good in low temperature characteristics, and has high reliability for cold regions in winter.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  Prototype oils 1 to 7 to be used as vehicle bearing lubricating oils were prepared at the blending amounts shown in Tables 1 and 2.

As PAO (poly-α-olefin), 1-decene polymerized and having a kinematic viscosity (40 ° C.) of 47.6 mm ² / s was used.

The mineral oil has a kinematic viscosity (40 ° C.) of 45.4 mm ² / s, a kinematic viscosity (100 ° C.) of 7.5 mm ² / s, a viscosity index of 131, a saturation content of 99% by weight, and a pour point of −12. The one having a flash point of 5 ° C., a flash point of 256 ° C., and a sulfur content of 1 ppm was used.

As the olefin copolymer, an ethylene-propylene copolymer having a number average molecular weight of 3700 and a kinematic viscosity (40 ° C.) of 37500 mm ² / s was used.

  As the antioxidant, N- (p-tert-octylphenyl) -1-naphthylamine was used.

  As the ester, ditridecyl adipate was used.

  In addition, in common, alkenyl succinic acid ester is added as 0.03% by weight as a rust inhibitor, 1% by weight of tricresyl phosphate is used as an extreme pressure agent, and 5% by weight of dimethylsiloxane is added as an antifoaming agent. did.

  For comparison with prototype oils 1 to 7, “JR Super Turbine 68” (made by Japan Energy), which is a commercially available bearing oil for vehicles, was evaluated, and the results are also shown in Table 2 as commercial oils.

  As an evaluation method, the kinematic viscosity and the viscosity index conform to JIS K2283, the pour point conforms to JIS K2269, and the rotary cylinder type oxidation stability test (RBOT, 150 ° C.) conforms to JIS K2514. Oxidation stability test (ISOT, 165.5 ° C., 288 hr) was measured according to JIS K2514 for the degree of contamination of the lubricating oil after the test (SAE ARP598, weight method, 0.8 μ, mg / 100 ml). For long-term oxidation stability, the turbine oil oxidation stability test method (JIS K2515) was used at a temperature of 120 ° C., and the degree of contamination after 2000 hours (mg / 100 ml) was measured.

  The trial oils 1 to 5, especially the trial oils 1 to 3, have a low pour point and excellent low-temperature characteristics as compared with the trial oils 6 and 7 and commercially available products. In addition, the trial oils 1 to 5, especially the trial oils 1 to 2, have a high RBOT value and a low degree of contamination due to oxidation compared to the trial oils 6 and 7 and commercially available products, and thus have excellent thermal and oxidation stability. .

  The vehicular bearing lubricating oil of the present invention can be used for bearings of vehicles such as railways and automobiles, particularly for vehicles that perform high-speed operation and for vehicles that travel in cold regions.

Claims (3)

A base oil containing 50 to 100% by weight of a poly-α-olefin having a kinematic viscosity (40 ° C.) of 15 to 60 mm ² / s;
2 to 5% by weight of an olefin copolymer composed of an ethylene-propylene copolymer having a kinematic viscosity (40 ° C.) of 300 to 40000 mm ² / s and a number average molecular weight of 1000 to 4000 ;
Containing 0.2 to 3% by weight of an amine-based antioxidant,
A vehicle bearing lubricant having a viscosity index of 140 to 160, a kinematic viscosity (40 ° C) of 20 to 80 mm ² / s, and a pour point of -50 ° C or less .   The vehicle base lubricant according to claim 1, wherein the base oil contains 0 to 50% by weight of a mineral oil base oil having a saturation content of 90% or more and a viscosity index of 100 or more in chromatographic analysis.   Furthermore, the bearing lubricating oil for vehicles of Claim 1 or 2 which contains 0.5 to 5weight% of ester.