JP2007099856A - Water resistant grease composition, and rolling bearing for water pump, wave-activated generator and dredging machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water resistant grease composition which suppresses development of white tissue separation and corrosion and can keep good lubrication for a long time, and to provide a rolling bearing for a water pump, a wave-activated generator or a dredging machine which is obtained by sealing the water resistant grease composition and is excellent in water resistance. <P>SOLUTION: The grease composition comprises a base oil composed of at least one lubricating oil selected from a mineral oil and a synthetic oil and having a kinematic viscosity at 40°C of 70-250 mm<SP>2</SP>/s and a thickening agent, and it further comprises at least one selected from a carboxylic acid-based rustproof additive, a carboxylate-based rustproof additive, and an ester-based rustproof additive in an amount of 0.1-20 mass%. This grease composition is sealed in a rolling bearing for a water pump, a wave-activated generator or a dredging machine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water-resistant grease composition that exhibits excellent lubricating performance even when water is mixed therein. The present invention also relates to a rolling bearing that is incorporated in a water pump, wave power generator, or dredger that comes into contact with water and exhibits an excellent lubrication life even when water is mixed.

  Water pump that pumps and circulates cooling water to the water-cooled engine of automobiles, wave power generators that generate power using wave energy, various dredgers and dredging robots that dredge, transport, and post-process bottom mud from the ocean and lakes Since they constantly come into contact with water, rolling bearings incorporated in these often cause water to be mixed into the encapsulated grease and cause poor lubrication. Regarding the influence of moisture on such grease, for example, Furumura et al., When 6% moisture is mixed in lubricating oil (# 180 turbine oil), the rolling fatigue life is reduced to a fraction of 20 to 20% compared to the case where it is not mixed. It has been reported that it decreases to a factor of 1 (Saburo Furumura, Shinichi Shirota, Kiyoshi Hirakawa: NSK Bearing Journal, No.636, pp.1-10, 1977) . Schatzberg et al. Also reported that the rolling strength of steel decreased by 32 to 48% with only 100 ppm of water in the lubricating oil (P. Schtzberg, IMFelsen: Effects of water and oxygen during rolling contact lubrication, Wear 12, pp.331-342, 1968).

  Such a decrease in life is considered that hydrogen generated from mixed water acts on the bearing material and causes metal peeling called white tissue peeling. In order to prevent such peeling, grease added with a passive oxidizing agent such as sodium nitrite (for example, see Patent Document 1), grease added with an organic antimony compound or an organic molybdenum compound (for example, see Patent Document 2), Improvement of grease has been performed, such as grease added with an inorganic compound having a particle size of 2 μm or less (see, for example, Patent Document 3). These prevent the hydrogen from entering the bearing material by forming a film derived from the additive at the rolling contact portion, but rolling of the rolling element occurs due to vibration or speed change until the film is formed. Then, metal peeling may occur at the rolling contact portion.

  As measures other than the improvement of grease, use of stainless steel as a bearing material (for example, refer to Patent Document 4), making a rolling element made of ceramics (for example, refer to Patent Document 5), etc. have been proposed. Bearings made of these materials are generally expensive.

  In addition, iron such as bearing steel has a problem that corrosion (rust) is easily caused by water and abnormal noise is generated from the bearing. In bearings where water can be mixed, it is very important to have corrosion resistance, and corrosion resistance is simultaneously imparted by the same method as described above, but it has the effect of suppressing the occurrence of rust. Not enough.

Japanese Patent No. 2878749 Japanese Patent No. 3512183 Japanese Patent Laid-Open No. 9-169989 JP-A-3-173747 JP-A-4-244624

  The present invention has been made in view of such a situation, and even when moisture is mixed, a water-resistant grease composition capable of suppressing the occurrence of white structure peeling and corrosion and maintaining good lubrication for a long time. The purpose is to provide goods. Another object of the present invention is to provide rolling bearings for water pumps, wave power generators, and dredgers, which are filled with such a water-resistant grease composition and are excellent in water resistance.

In order to achieve the above object, the present invention provides the following water-resistant grease composition and rolling bearings for water pumps, wave power generators or dredgers.
(1) A grease composition enclosed in a rolling bearing incorporated in a device or device that comes into contact with water, which comprises at least one lubricating oil selected from mineral oil and synthetic oil, and has a kinematic viscosity at 40 ° C. of 70 to Grease containing at least one selected from a carboxylic acid anticorrosive additive, a carboxylate anticorrosive additive and an ester anticorrosive additive, including a base oil of 250 mm ² / s and a thickener. A water-resistant grease composition comprising 0.1 to 20% by mass of the total amount.
(2) A rolling bearing incorporated in a water pump that pumps and circulates cooling water to a water-cooled engine, wherein a plurality of rolling elements are rotatably arranged between an inner ring and an outer ring, A water-bearing rolling bearing according to claim 1, wherein the water-resistant grease composition described in (1) is enclosed in a space formed between the outer rings and in which the rolling elements are disposed.
(3) A rolling bearing incorporated in a wave power generator, wherein a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and are formed between the inner ring and the outer ring and formed with the rolling element. A rolling bearing for a wave power generator, characterized in that the water-resistant grease composition described in (1) above is enclosed in a space in which a moving body is disposed.
(4) A rolling bearing incorporated in a forward ship or a dredging robot, wherein a plurality of rolling elements are rotatably arranged between an inner ring and an outer ring, and are formed between the inner ring and the outer ring. A rolling bearing for dredgers characterized in that the water-resistant grease composition described in (1) is enclosed in a space in which the rolling elements are disposed.

  The water-resistant grease composition of the present invention maintains good lubricity by using a base oil having a specific kinematic viscosity and contains carboxylic acid-based, carboxylate-based, and ester-based rust preventive additives. Excellent resistance to corrosion and white tissue peeling.

  Further, the rolling bearings for water pumps, wave power generators, and dredging machines of the present invention show excellent lubrication life even when moisture is mixed by enclosing such a water-resistant grease composition. .

  Hereinafter, the present invention will be described in detail.

In the water-resistant grease composition of the present invention, the base oil is selected from mineral oil and synthetic oil, and the kinematic viscosity at 40 ° C. is 70 to 250 mm ² / s. By setting the kinematic viscosity within the above range, it is possible to eliminate problems such as the generation of abnormal noise at low temperature startup and the loss of oil film at high temperatures. In order to ensure such an effect, the kinematic viscosity at 40 ° C. is preferably 120 to 185 mm ² / s.

  Mineral oil can be used that is purified by appropriately combining vacuum distillation, oil removal, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, white clay purification, hydrorefining, and the like.

Synthetic oils include hydrocarbon oils, aromatic base oils, ester oils, ether oils, and the like. Examples of the hydrocarbon oil include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, poly-α-olefin such as 1-decene and ethylene co-oligomer, and hydrides thereof. Examples of the aromatic oil include alkylbenzenes such as monoalkylbenzene and dialkylbenzene, and alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene and polyalkylnaphthalene. Examples of ester oils include dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methyl acetyl cinnolate, or trioctyl trimellitate. Aromatic ester oils such as tridecyl trimellitate and tetraoctyl pyromellitate, and further trimethylolpropane caprylate, trimethylolpropane verargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol verargonate, etc. Polyol ester oils, and complex ester oils that are oligoesters of polyhydric alcohols and mixed fatty acids of dibasic acids and monobasic acids are also exemplified. Examples of ether oils include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether, or monoalkyl triphenyl ether, alkyl diphenyl ether, dialkyl diphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyl tetra And phenyl ether oils such as phenyl ether and dialkyl tetraphenyl ether. These lubricating oils can be used alone or as a mixture, and are adjusted to the above-mentioned preferable kinematic viscosity. Among them, a base oil using an ester oil having a kinematic viscosity at 40 ° C. of 120 to 185 mm ² / s alone is preferable. .

  As the thickener, both organic and inorganic thickeners can be used, but those that do not contain heavy metals are preferable in consideration of the influence on the environment. Specifically, metal soaps such as lithium soap, calcium soap, aluminum soap, magnesium soap, sodium soap, or composite soaps thereof, urea compounds, bentonite, silica, carbon black, and the like can be suitably used. Of these, metal soaps and urea compounds are preferred. These may be used alone or in combination.

  The blending amount of the thickener is not limited as long as the grease can be formed and maintained with the above base oil, but is preferably 5 to 35 mass%, more preferably 5 to 25 mass% of the total amount of grease. In the case of mixed use, the total amount is within this range.

  In this invention, at least 1 sort (s) chosen from a carboxylic acid type rust preventive additive, a carboxylate type | system | group anticorrosive additive, and an ester type rust preventive additive is added. The addition amount is 0.1 to 20% by mass based on the total amount of grease in both cases of single use and mixed use. When the addition amount is less than 0.1% by mass, the effect of suppressing white structure peeling and corrosion cannot be sufficiently obtained. On the other hand, when the addition amount exceeds 20% by mass, the adhesion amount of the rust preventive agent on the surface of the bearing member is excessively increased, and the formation of an oxide film or the like derived from the grease composition of the present invention is hindered to cause white tissue peeling. It may occur. When the antirust performance is ensured and white structure peeling is taken into consideration, the addition amount is preferably 0.25 to 15% by mass with respect to the total amount of grease.

  Examples of the carboxylic acid-based antirust agent include monocarboxylic acids, linear fatty acids such as lauric acid and stearic acid, and saturated carboxylic acids having a naphthene nucleus. Dicarboxylic acids include succinic acid derivatives such as succinic acid, alkyl succinic acid, alkyl succinic acid half ester, alkenyl succinic acid, alkenyl succinic acid half ester, succinimide, hydroxy fatty acid, mercapto fatty acid, sarcosine derivative, and wax or Examples thereof include an oxidized wax such as an oxide of petrolatum.

  Examples of carboxylate-based anticorrosive additives include fatty acid, naphthenic acid, abietic acid, lanolin fatty acid, alkenyl succinic acid, and metal salts of amino acid derivatives. Metal elements include cobalt, manganese, zinc, and aluminum. , Calcium, barium, lithium, magnesium, copper and the like.

  Examples of ester-based rust preventive additives include partial esters of polyhydric alcohols such as sorbitol, pentaerythritol, sucrose, and glycerin with carboxylic acids such as oleic acid and lauric acid, and higher grades such as oleyl alcohol, stearyl alcohol, and lauryl alcohol. Fatty acid alcohol etc. are mentioned.

  In order to suppress the occurrence of white tissue peeling, it becomes more effective if it becomes easier to form an oxide film at the rolling contact portion in addition to the action of the rust preventive additive. Therefore, the water-resistant grease composition includes a dialkyldithiocarbamic acid compound represented by the following general formula (1), a dialkyldithiophosphate compound represented by the general formula (2), and general formulas (3) to (5). It is preferable to add at least one organometallic salt selected from an organic zinc compound represented by (II) and a zinc alkylxanthate represented by the general formula (6).

In the general formulas (1) and (2), M represents a metal species, and specifically can be selected from Sb, Bi, Sn, Ni, Te, Se, Fe, Cu, Mo, and Zn. R ₁ and R ₂ may be the same group or different groups, and are selected from an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group. Particularly preferred groups as R ₁ and R ₂ include 1,1,3,3-tetramethylbutyl group, 1,1,3,3-tetramethylhexyl group, 1,1,3-trimethylhexyl group, 1, 3-dimethylbutyl group, 1-methylundecane group, 1-methylhexyl group, 1-methylpentyl group, 2-ethylbutyl group, 2-ethylhexyl group, 2-methylcyclohexyl group, 3-heptyl group, 4-methylcyclohexyl group N-butyl group, isobutyl group, isopropyl group, isoheptyl group, isopentyl group, undecyl group, eicosyl group, ethyl group, octadecyl group, octyl group, cyclooctyl group, cyclododecyl group, cyclopentyl group, dimethylcyclohexyl group, decyl group Tetradecyl group, docosyl group, dodecyl group, tridecyl group, trimethylcyclohexane Sil group, nonyl group, propyl group, hexadecyl group, hexyl group, henicosyl group, heptadecyl group, heptyl group, pentadecyl group, pentyl group, methyl group, tert-butylcyclohexyl group, tert-butyl group, 2-hexenyl group, 2 -Methallyl group, allyl group, undecenyl group, oleyl group, decenyl group, vinyl group, butenyl group, hexenyl group, heptadecenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, tert-butylphenyl group, second pentylphenyl group N-hexylphenyl group, tertiary octylphenyl group, isononylphenyl group, n-dodecylphenyl group, phenyl group, benzyl group, 1-phenylmethyl group, 2-phenylethyl group, 3-phenylpropyl group, 1, 1-dimethylbenzyl group, 2-phenylisopropyl group, 3-phenyl Niruhekishiru group, benzhydryl group, there is a biphenyl group and the like, and these groups may have an ether group.

In the general formulas (3) to (5), R ₃ and R ₄ may be the same group or different groups, and are selected from a hydrocarbon group having 1 to 18 carbon atoms and a hydrogen atom. In particular, R ₃ and R ₄ are both hydrogen atoms, mercaptobenzothiazole zinc (general formula (3)), benzoamidothiophenol zinc (general formula (4)), mercaptobenzimidazole zinc (general formula (5)). Can be preferably used.

In the general formula (6), _{R 5} is a hydrocarbon group having 1 to 18 carbon atoms.

  The amount of the above-mentioned organometallic salt added is 0.1 to 20% by mass based on the total amount of grease for both single use and mixed use. When the addition amount of the organic metal salt is less than 0.1% by mass, there is no effect in promoting the formation of an oxide film, and when it exceeds 20% by mass, an improvement in the effect corresponding to the increment cannot be obtained, and oxidation with the bearing material is not achieved. The reaction may be accelerated abnormally to cause corrosion and abnormal wear. The amount of the organic metal salt added is particularly preferably in the range of 0.5 to 10% by mass.

  Furthermore, you may add the other additive conventionally added to the grease composition to a grease composition as needed. For example, amine antioxidants such as phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenylamine, phenylenediamine, oleylamidoamine, phenothiazine; pt-butyl-phenyl salicylate, 2,6-di-tert-butyl- p-phenylphenol, 2,2'-methylenebis (4-methyl-6-t-octylphenol), 4,4'-butylidenebis-6-t-butyl-m-cresol, tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl ) Benzene, n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate 2-n-octyl-thio-4,6-di (4′-hydroxy-3 ′, 5′-di-t-butyl) phenoxy-1,3,5-triazine, 4,4′-thiobis (6 -T-butyl-m-cresol), 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole and other phenolic antioxidants such as hindered phenols; Fatty acids such as oleic acid and stearic acid, alcohols such as lauryl alcohol and oleyl alcohol, amines such as stearylamine and cetylamine, phosphate esters such as tricresyl phosphate, oiliness improvers such as animal and vegetable oils; extreme pressure agents such as organic molybdenum A metal deactivator such as benzotriazole can be added. Among these, those not containing heavy metals are preferable from the environmental viewpoint. The addition amount of these additives is not particularly limited as long as the effects of the present invention are not impaired, but 0.1 to 20% by mass of the total amount of the grease composition is appropriate, and 0.1 to 15 % By mass is preferable, more preferably 0.1 to 10% by mass, and particularly preferably 0.1 to 5% by mass. If the addition amount is less than 0.1% by mass, the effect of the additive will not be sufficiently exhibited, and even if it is added in excess of 20% by mass, the effect cannot be improved, and the base oil amount will be relatively small, so that lubricity will be achieved. May decrease.

  The present invention also relates to rolling bearings for water pumps, wave power generators, and dredgers, in which the above water-resistant grease composition is enclosed.

  FIG. 1 is a cross-sectional view showing an example of a water pump that pumps and circulates cooling water of an automobile engine. The illustrated water pump 1 is configured such that a rotating shaft 12 to which an impeller 14 is fixed is supported on a casing 13 by a rolling bearing 10 that is disposed at an interval in the axial direction. The cooling water is sealed by a mechanical seal 15 disposed between the impeller 14 and the rolling bearing 10. In the present invention, the water resistant grease composition is enclosed in the rolling bearing 10. Reference numeral 11 denotes a pulley that drives the water pump 1 with a belt connected to the engine.

  FIG. 2 is a schematic view showing an example of a self-propelled dredger. The illustrated dredger 21 travels on a crawler 23, and a rudder 29 including an excavation cutter 28 at the tip is vertically moved by a vertical pivot shaft 26 and a horizontal pivot shaft 27 at a front end portion thereof. It is connected so that it can turn horizontally. FIG. 3 is an enlarged view of the periphery of the pivot shafts 26 and 27. The upper and lower ends of the pivot shaft 26 in the vertical direction are rotatably supported by bearings 31a and 31b. A ladder support base 39 is provided, and the base end of the ladder 29 is supported by a horizontal pivot shaft 27 so as to be rotatable in the vertical direction. Further, the upper and lower ends of the vertical pivot shaft 26 are rotatably supported by bearings 31a and 31b. The upper bearing 31a is supported at the tip of the horizontal shaft 32 supported in the horizontal direction with respect to the airframe 30 via the bearing 32a. On the other hand, the bearing 31b at the lower end is locked to an arcuate guide 33 fixed to the end face of the machine body 30 so as to be movable along the arcuate shape. Further, a hydraulic cylinder 36 for vertically rotating driving is interposed between the ladder 29 and the bearing 31b so that the vertical angle of the ladder 29 is adjusted. In the present invention, the grease composition is enclosed in the bearings 31a, 31b, and 32a.

  FIG. 4 is a schematic view showing a wave-dissipating block using a wave power generator. The cylindrical tube 41 that also serves as a wave-dissipating block is installed such that its lower part is submerged in the coastal sea. The water surface in the cylindrical tube 41 rises as indicated by the arrow in the case of a rush wave as shown in (a), so that the air in the cylindrical tube 41 blows out through the wind tube 47. Further, at the time of the pulling wave, as shown in (b), the water surface descends as shown in the figure, so that air is sucked into the cylindrical tube 41. A waterproof casing 49 is installed at the upper end of the cylindrical tube 41, and a generator 50 as shown in FIG. A wells turbine 58 is fixed to the rotor shaft 51 of the generator 50, and the rotor shaft 51 is waterproofed by a waterproof thrust bearing 52. Due to the action of the waves, the wind turbine 58 is alternately subjected to wind in the opposite direction, but the well turbine 58 has a characteristic that it continues to rotate in a constant direction even when the wind in the opposite direction is alternately applied. Electric power is generated by rotating the generator 50. The waterproof casing 59 is attached to the wind tube 47 by a support pipe 53, and a submarine cable 54 for taking out the electric power generated by the generator 50 is inserted into one of the support pipes 53. The support pipe 53 is provided with a waterproof putty 55 to prevent water from entering the waterproof casing 49 from the support pipe 53. In the present invention, the above grease composition is sealed in the waterproof thrust bearing 52.

  Since water pumps, wave power generators, and dredgers have many opportunities to come into contact with water, water easily enters the rolling bearings incorporated therein. However, since the above grease composition contains a specific rust preventive additive, the rolling bearings for water pumps, wave power generators, and dredgers of the present invention are effective in corrosion even if moisture is mixed in. Therefore, the white tissue peeling can be effectively suppressed and the life is prolonged.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is further demonstrated, this invention is not restrict | limited at all by this.

(Examples 1-4, Comparative Examples 1-2)
The test grease prepared with the formulation shown in Table 1 was enclosed in a tapered roller bearing “HR30205 (inner diameter 25 mm, outer diameter 52 mm, width 16.25 mm)” manufactured by NSK Ltd. to produce a test bearing. In each test grease, phenolic antioxidant (2,6-di-t-butylcresol; manufactured by Tokyo Chemical Industry Co., Ltd.), amine antioxidant (p, p'-dioctyldiphenylamine; Tokyo Chemical Industry Co., Ltd.) )), A rust inhibitor (calcium phosphate; “Nasul R1-CA” manufactured by King) and an extreme pressure agent (ashless sulfur; “Vanrube 7723” manufactured by Vanderbilt) are added in an amount of 0.5% by mass. And after inject | pouring water into this test bearing so that it might become 1 mass% with respect to the sealing grease whole quantity, it was continuously rotated for 100 hours at 120 degreeC, radial load 98N, axial load 1470N, and rotational speed 3500rpm. After rotation, the test bearing was disassembled, and the presence or absence of rust and peeling was visually observed. The results are shown in Table 1.

  As shown in Table 1, according to the present invention, at least one selected from a carboxylic acid-based rust preventive additive, a carboxylate-based rust preventive additive and an ester-based rust preventive additive is 0.1 to 20% by mass of the total amount of grease. It can be seen that by encapsulating the grease composition of each example contained in the ratio, the anti-rust performance and anti-peeling effect are extremely good and a long-life rolling bearing is obtained.

It is a partial sectional view showing an example of a water pump. It is the schematic which shows an example of a dredge. It is a figure which expands and shows a part of FIG. It is the schematic which shows an example of a wave power generator. It is an enlarged view which shows the specific structure of a wave power generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water pump 12 Rotating shaft 13 Casing 14 Impeller 15 Mechanical seal 21 Anchor 23 Crawler 26, 27 Pivoting shaft 28 Excavation cutter 29 Ladder 31a, 31b, 32a Bearing 41 Cylindrical tube 47 Wind tube 49 Waterproof casing 50 Generator 51 Rotor Shaft 52 Waterproof thrust bearing 58 Wells turbine

Claims (4)

A grease composition enclosed in a rolling bearing incorporated in a device or device that comes into contact with water, comprising a lubricating oil selected from mineral oil and synthetic oil, and having a kinematic viscosity at 40 ° C. of 70 to 250 mm ² / s containing a base oil and a thickener, and at least one selected from a carboxylic acid anticorrosive additive, a carboxylate anticorrosive additive and an ester anticorrosive additive A water-resistant grease composition containing 1 to 20% by mass.   A rolling bearing incorporated in a water pump that pumps and circulates cooling water to a water-cooled engine, and a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and the inner ring and the outer ring A rolling bearing for a water pump, wherein the water-resistant grease composition according to claim 1 is enclosed in a space formed between the rolling elements.   A rolling bearing incorporated in a wave power generator, wherein a plurality of rolling elements are rotatably disposed between an inner ring and an outer ring, and the rolling elements are formed between the inner ring and the outer ring. A rolling bearing for a wave power generator, characterized in that the water-resistant grease composition according to claim 1 is enclosed in a space provided.   A rolling bearing incorporated in a forward ship or a dredging robot, wherein a plurality of rolling elements are rotatably arranged between an inner ring and an outer ring, and the rolling element is formed between the inner ring and the outer ring. A rolling bearing for dredgers, characterized in that the water-resistant grease composition according to claim 1 is enclosed in a space in which is disposed.

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