JP2002212341A - Rubber material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber material composition having excellent wear resistance and little heat generation due to friction, and to seal a rolling device used in grease lubrication in a harsh environment where a large amount of water and dust are present. Provided is a rubber material composition suitably used for an apparatus. SOLUTION: The rubber material composition is configured to have 100 parts by weight of carboxylated acrylonitrile butadiene rubber and 20 to 90 parts by weight of carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber material composition suitably used for a sealing device provided in a rolling device such as a rolling bearing, a linear guide device, and a ball screw. The present invention relates to a rubber material composition suitably used for a sealing device of a rolling device used for grease lubrication under a severe environment existing in the present invention.

[0002]

2. Description of the Related Art Conventionally, a rolling device provided with a sealing device such as an oil seal is provided on an elastic member (a contact tip (seal lip portion) which comes into sliding contact with a mating member such as a shaft) as described above. Even in a severe environment, a rubber material composition in which an additive is appropriately blended with nitrile rubber, acrylic rubber, fluorine rubber or the like has been used.
A sealing device using such a rubber material composition for an elastic member has sufficient sealing performance even in grease lubrication in an environment with little water or dust, that is, in a clean environment.

However, since bearings for vehicles and hub unit bearings for automobiles used for railway axles and the like are used outdoors, they are exposed to a large amount of water (rainwater and washing water) and dust, and lubrication of the sealing device. May not be maintained sufficiently. As a result, frictional heat is generated between the contact tip of the sealing device and the shaft, which accelerates the deterioration of the grease or wears the contact tip that is in sliding contact with the shaft, lowering the sealing performance, and causing water and dust inside the bearing. Inconveniences such as intrusion may occur, and as a result, the life of the bearing may be shortened.

[0004] In addition, although the bearings for steel rolling mills are used indoors, the use environment is such that a large amount of dust such as coke, iron ore, and scale is present and is exposed to a large amount of cooling water. It was even worse than vehicle bearings and automotive hub unit bearings used for railway axles and the like. Therefore, the same problem as described above may occur.

[0005] Next, as an example of a sealing device provided in a rolling device used under such a severe environment, an oil seal provided in a bearing for a railway vehicle will be described in detail. As such an oil seal, for example, FIG.
Oil seal 101 with garter spring as shown in FIG.
There is. This oil seal 101 is
4a, a main lip 104b, and a garter spring 106 arranged on the outer periphery of the main lip 104b, and are interposed between the shaft S and the seal case 102. And
Generally, a spring cover 103 is press-fitted and fixed between the seal case 102 and the fitting portion 105a of the metal ring 105.

The main lip 104b (elastic member) of the oil seal 101 is generally made of a nitrile rubber composition, an acrylic rubber composition, a fluoro rubber composition, or the like.

[0007]

The oil seal 101 as described above is often used continuously for a long time under grease lubrication in railway vehicle bearings. Therefore, heat is generated between the shaft S and the main lip 104b that slides on the shaft S, so that the grease of the bearing is deteriorated, and the life of the bearing may be shortened.

The main lip 1 is exposed to water.
If the lubrication of the main lip 104b is insufficient, the abrasion of the main lip 104b is accelerated, and the sealing property is reduced at an early stage. Again, the life of the bearing may be shortened. As described above, the conventional oil seal 101 in which the main lip 104b (elastic member) is made of the nitrile rubber composition, the acrylic rubber composition, the fluororubber composition, or the like, cannot be used under the above severe operating conditions.
Sliding contact between the main lip 104b and the shaft S causes the main lip 104
b easily wears out early, and the sealing performance between the main lip 104b and the shaft S is reduced, so that the original function of the oil seal is often not sufficiently exhibited. Further, even before the wear progresses, the grease deteriorates due to frictional heat, and similarly, the function of the oil seal is often not sufficiently exhibited.

Accordingly, the present invention solves the above-mentioned problems of the prior art, and provides a rubber material composition having excellent abrasion resistance and low heat generation due to friction, and in a severe environment where a large amount of water and dust are present. An object of the present invention is to provide a rubber material composition suitably used for a sealing device of a rolling device used for grease lubrication below.

[0010]

In order to solve the above-mentioned problems, the present invention has the following arrangement. That is, the rubber material composition of the present invention comprises 100 parts by weight of a carboxylated acrylonitrile butadiene rubber and carbon black 20.
９０90 parts by weight. Hereinafter, the rubber material composition of the present invention will be described in detail.

The rubber material composition of the present invention has carboxylated acrylonitrile butadiene rubber (carboxyl-modified nitrile rubber) as a raw rubber and carbon black as a reinforcing filler. If necessary, wear improvers, vulcanizing additives, anti-aging agents, lubricants,
Various additives such as lubricating oil and processing aids may be further added. Such a rubber material composition can be suitably used as a material of an elastic member (a contact tip (seal lip portion) that comes into sliding contact with a mating member such as a shaft) constituting a sealing device provided in a rolling device.

The carboxylated acrylonitrile-butadiene rubber as a raw material rubber has a structure in which ordinary acrylonitrile-butadiene rubber has a carboxyl group. In addition, not only the double bond caused by butadiene but also the carboxyl group promotes a crosslinking reaction in the rubber material composition and increases the crosslinking density. The tensile strength, abrasion resistance and bending fatigue resistance of the composition are improved.

For example, in the case of ordinary acrylonitrile butadiene rubber, the tensile strength when the elongation at break is 200% is about 15 to 20 MPa, while in the case of carboxylated acrylonitrile butadiene rubber, the elongation at break is 20 MPa.
The tensile strength at 0% is 25 MPa or more. Therefore, if the contact tip of the sealing device used for the rolling device is made of such a rubber material composition, the contact tip quickly follows the rotational movement of the sealing device and is less likely to be damaged.

Such a carboxylated acrylonitrile-butadiene rubber is prepared by adding a carboxyl group-containing monomer in addition to acrylonitrile and butadiene, which are ordinary monomers used in the polymerization of acrylonitrile-butadiene rubber, during production by emulsion polymerization or the like. Acrylic acid, methacrylic acid, and the like are further added and copolymerized.

The amount of the carboxyl group-containing monomer to be added is 20% by weight or less, preferably 3 to 10% by weight of the total monomers.
Is preferable. However, since the carboxyl group-containing monomer is difficult to polymerize, each monomer does not polymerize according to the added weight ratio (ie, the weight ratio of the added monomer and the obtained polymer The composition ratio of the carboxyl group-containing monomer component in the obtained polymer is always lower than the weight ratio added.

Actual carboxyl groups in the obtained polymer
Is represented by an acid equivalent of 1 × 10 ^-Four~ 9 × 10^-2ep
hr is preferable. Acid equivalent of 1 × 10^-Foureph
If less than r, the normal (uncarboxylated)
I) Compared to acrylonitrile butadiene rubber,
The degree of change is almost unchanged, so the tensile strength of the rubber material composition
There is almost no improvement in the degree and wear resistance.

On the other hand, if the acid equivalent exceeds 9 × 10 ^-2 ephr, the amount of carboxyl groups increases and the crosslinking density becomes too high, which may cause problems in the physical properties of the rubber material composition described later. Specifically, the spring hardness is 9
If it exceeds 0, the tensile elongation at break may be less than 200%, and the risk of scorch increases. To make these problems less likely to occur, the acid equivalent is 2 ×
More preferably, the range is 10 ^{−3 to} 5 × 10 ⁻² ephr.

The acid equivalent is a value measured as follows. That is, the rubber is dissolved in acetone and n
After reprecipitation purification with hexane, the reprecipitated purified rubber is redissolved in pyridine. Then, this rubber solution is used for 0.1.
Using an ethanol solution of 02N potassium hydroxide and titration with thymolphthalein as an indicator, 100 g of rubber
Was determined as an equivalent to

There are several kinds of carboxylated acrylonitrile-butadiene rubbers in the same manner as ordinary acrylonitrile-butadiene rubber. Depending on the content of acrylonitrile, from the lower one, low nitrile, medium nitrile, medium-high nitrile, high nitrile, extreme There is high nitrile. However, considering heat resistance and oil resistance, medium nitrile, medium and high nitrile, and high nitrile are preferable, and the content of acrylonitrile is preferably 20 to 40% by weight.

Next, carbon black will be described. Carbon black is added as a reinforcing filler that increases the strength of the carboxylated acrylonitrile butadiene rubber. Specifically, ISAF (Intermed
iate Super Abrasion Furnaceblack), MAF (Mediu
m Abrasion Furnace black), SRF (Semi-Reinforc)
ing Furnace black), GPF (General Purpose Furna)
ce black), FT (Fine Thermal Furnace black),
MT (Medium Thermal Furnace black), HAF (High
Abrasion Furnace black), FEF (Fast Extruding)
Furnace black) and the like, but in order to improve the wear resistance, HAF, FEF having high reinforcing properties are used.
Is more preferred.

When a white reinforcing filler such as hydrated silica, clay, talc, calcium carbonate, diatomaceous earth, and wollastonite is used alone, sufficient abrasion resistance is not obtained because the reinforcing property is not sufficient. I can't get it. Therefore, when the contact tip of the sealing device is configured with a rubber material composition using such a white reinforcing filler alone, abrasion is likely to occur due to the sliding contact between the contact tip and the counterpart material, and as a result, The sealing performance between the contact tip and the counterpart material is reduced. In addition, due to the rotational movement of the sealing device such as an oil seal, a large amount of heat is easily generated between the contact tip and the counterpart material, and the heat easily causes grease in the rolling device to deteriorate.

If carbon black is used as the reinforcing filler, the above-mentioned problems are unlikely to occur. That is, the compatibility with the carboxylated acrylonitrile-butadiene rubber is good and the reinforcing property is sufficiently high, so that the rubber material composition has excellent wear resistance. Therefore, wear of the contact tip is suppressed. Furthermore, since the thermal conductivity of the rubber material composition is improved by adding carbon black, heat generated by friction between the contact tip and the counterpart material is easily diffused. Therefore, the grease in the rolling device is hardly deteriorated by heat, and the life of the rolling device is improved.

Considering the physical properties of the rubber material composition, the amount of carbon black needs to be 20 to 90 parts by weight based on 100 parts by weight of the carboxylated acrylonitrile butadiene rubber. If it is less than 20 parts by weight, sufficient reinforcing properties are not exhibited, and if it is more than 90 parts by weight, the hardness of the rubber material composition increases and the elongation decreases,
The inherent rubber elasticity is reduced.

The carboxylated acrylonitrile-butadiene rubber contains a vulcanizing additive and an antioxidant as essential components in addition to carbon black. In some cases, however, a processing aid, a wear modifier, a lubricating oil, A lubricant or the like may be added. Examples of the wear improver include polyolefin particles and spherical carbon fine particles. Specific examples of the polyolefin particles include particles made of polyethylene and polypropylene, and more preferred are particles made of carboxyl-modified polyethylene (maleic anhydride-modified polyethylene) and carboxyl-modified polypropylene (maleic anhydride-modified polypropylene). Can be

When polyethylene and polypropylene are carboxyl-modified, carboxyl groups in the structure make it easier to adsorb to various rubbers and oxides. Also, the carboxyl group present in the carboxylated acrylonitrile butadiene rubber, which is the raw material rubber, has the same effect, so that the synergistic effect of the carboxyl acrylonitrile butadiene rubber further enhances the mechanical strength such as tensile strength, abrasion resistance, and bending fatigue resistance. It is thought that.

The amount of the polyolefin particles to be added is preferably 10 to 60 parts by weight based on 100 parts by weight of the carboxylated acrylonitrile butadiene rubber in view of the balance between the wear resistance of the rubber material composition and other physical properties. If the amount of the polyolefin particles is less than 10 parts by weight based on 100 parts by weight of the carboxylated acrylonitrile butadiene rubber, the effect of improving the wear resistance is low. On the contrary, 60
If the amount exceeds the weight part, the hardness of the rubber material composition increases and the elongation decreases, and the rubber elasticity decreases.

The spherical carbon fine particles (glassy carbon, spherical graphite) are obtained by carbonizing and firing phenol / formaldehyde resin in nitrogen at a temperature of 800 to 2000 ° C., and have an average particle size of about 2 to 40 μm. is there. Specifically, Bell Pearl C (registered trademark) manufactured by Kanebo Co., Ltd.
Is preferred. When such spherical carbon fine particles are present on the surface of the rubber material composition, the spherical carbon fine particles receive a load, so that the wear resistance of the rubber material composition is greatly improved. The mixing ratio of the spherical carbon fine particles is not particularly limited, but is preferably 5 to 20 parts by weight based on 100 parts by weight of the carboxylated acrylonitrile butadiene rubber.

Although the hardness of the rubber material composition is affected by the amount of the wear modifier added as described above, it is described in JIS K6301 from the viewpoint of sealing performance and followability when applied to a sealing device such as an oil seal. The hardness is preferably in the range of 50 to 90. If the hardness is less than 50, the contact tip (seal lip) is unnecessarily deformed when the sealing device performs a rotary motion. As a result, the frictional resistance during the operation of the rolling device increases, and smooth rotation becomes difficult.

When the hardness exceeds 90, the rubber elasticity is reduced as described above, so that the sealing property and the followability of the contact tip in the rotating motion are reduced. The life of the moving device may be shortened. The spring hardness of the rubber material composition is particularly preferably in the range of 70 to 80 in order to reduce the degree of deformation of the contact tip and particularly favor physical properties such as rubber elasticity.

Next, as a lubricant for improving lubricity, wax (low melting point fat) having a melting point of 75 to 140 ° C. is exemplified. Specific examples include paraffin wax, polyethylene wax, montan wax, carnauba wax, ester wax, stearoamide, oxystearamide, ercylamido, laurylamide, palmitylamide, behenamide, methylolamide, ethylene having the above melting point range. Bisoleylamide,
And stearyl oleylamide. Of these, polyethylene wax is most preferred. Such a lubricant is used as a carboxylated acrylonitrile butadiene rubber 10
Addition of 5 to 20 parts by weight with respect to 0 parts by weight improves the lubricity of the rubber material composition.

As the lubricating oil, ether oils, silicone oils, poly α-olefin oils,
Fluorine oil, fluorinated surfactant and the like can be mentioned. Among them, silicone oil is more preferable, and further,
Modified silicone oils having functional groups are particularly preferred.
When 2 to 20 parts by weight of such a lubricating oil is added to 100 parts by weight of the carboxylated acrylonitrile butadiene rubber, the lubricity of the rubber material composition is improved. Since the lubricating oil is liquid and easily blooms on the surface of the rubber material composition, the lubricating effect is easily exerted by adding a smaller amount than the lubricant.

Next, the vulcanizing additives will be described. Vulcanizing additives include vulcanizing agents (crosslinking agents), vulcanizing accelerators,
There are vulcanization accelerators. Examples of the vulcanizing agent (crosslinking agent) include various kinds of sulfur such as powdered sulfur, sulfur, precipitated sulfur and highly dispersible sulfur, morpholine disulfide, alkylphenol disulfide, N, N-dithio-bis (hexahydro-2H
Azepinone-2), a sulfur compound capable of producing sulfur such as thiuram polysulfide, dicumyl peroxide,
Di (t-butylperoxy) diisopropylbenzene,
And peroxides such as 2,5-dimethyl-2,5-di (benzoylperoxy) hexane and benzoyl peroxide. Of these, dispersibility, ease of handling,
From the viewpoint of heat resistance, it is preferable to use highly dispersible sulfur or morpholine disulfide.

When a sulfur vulcanizing agent is used, vulcanization of guanidine, aldehyde-ammonia, thiazole, sulfenamide, thiourea, thiuram, dithiocarbamate, xanthate, etc. Accelerators need to be used. Of these, when a small amount of highly dispersible sulfur is blended, thiuram-based tetramethylthiuram disulfide or the like or sulfenamide-based N-cyclohexyl-
It is preferable to use 2-benzothiazyl-sulfenamide in combination with thiazole-based 2-mercaptobenzothiazole and the like.

Further, examples of the vulcanization accelerator include metal oxides such as zinc oxide, metal carbonates, metal hydroxides, fatty acids such as stearic acid and derivatives thereof, and amines. Acrylonitrile butadiene rubber is liable to undergo premature vulcanization by zinc oxide, and therefore a combination of zinc peroxide and stearic acid is preferred. Zinc peroxide is present in the rubber material composition as it is at the temperature at the time of kneading of the rubber material composition, and generates zinc oxide at the time of vulcanization molding, so that early vulcanization occurs during kneading and storage. Nothing.

Examples of the antioxidants for preventing oxidative deterioration include amine-ketone condensation products, aromatic secondary amines, monophenol derivatives, bis or polyphenol derivatives, hydroquinone derivatives, sulfur-based antioxidants, and phosphorus-based antioxidants. Antioxidants and the like. Among them, 2,2,4-trimethyl-1,2-dihydroquinoline polymer of amine-ketone condensation product system, condensation reaction product of diphenylamine and acetone, N, N′- of aromatic secondary amine system Jee
β-naphthyl-p-phenylenediamine, 4,4′-bis- (α, α-dimethylbenzyl) diphenylamine,
N-phenyl-N '-(3-methacryloyloxy-2
-Hydroxypropyl) -p-phenylenediamine and the like are particularly preferred.

In order to prevent thermal decomposition and improve heat resistance, it is more preferable to use a secondary antioxidant together with the above antioxidant. Examples of the secondary aging inhibitor include sulfur-based 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salts thereof. Furthermore, as a sun crack preventing agent that suppresses the occurrence of cracks due to the action of sunlight or ozone,
About 0.5 to 2 parts by weight of waxes having a melting point of about 55 to 70 ° C. may be added to 100 parts by weight of the carboxylated acrylonitrile butadiene rubber.

Further, when it is necessary to improve the moldability, a plasticizer is appropriately added as a processing aid in addition to the above-mentioned additives. However, if there is no particular problem in molding, it may not be added. When it is added, it may be added in an amount of 3 to 20 parts by weight based on 100 parts by weight of the carboxylated acrylonitrile butadiene rubber. If added more than necessary, the rubber material composition softens and simultaneously bleeds out without being completely mixed. May come.

Specific examples of the plasticizer include phthalic acid diesters such as dioctyl phthalate, polyester plasticizers, polyether plasticizers, polyetherester plasticizers, and liquid nitrile rubber.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the rubber material composition according to the present invention will be described in detail with reference to the drawings. The rubber material composition was prepared by mixing the raw rubber, carbon black, and various additives at the ratios shown in Table 1 and performing the following steps.

[0040]

[Table 1]

First, various materials used (described in Table 1) will be described. -Raw material rubber A: Middle and high nitrile rubber (manufactured by JSR Corporation,
JSR NBR N230S), ratio of acrylonitrile monomer: 35% by weight Raw rubber B: carboxylated medium-high nitrile rubber (Nipol DN631 manufactured by Zeon Corporation), ratio of acrylonitrile monomer: 33.5% by weight Raw material Rubber C: carboxylated nitrile rubber (Nipol 1072, manufactured by Zeon Corporation), acrylonitrile monomer ratio: 27% by weight Carbon black A: HAF (manufactured by Mitsubishi Chemical Corporation)
Diablack H) ・ Carbon black B: FEF (Mitsubishi Chemical Corporation)
Diablack E) ・ Vulcanizing agent: Highly dispersible sulfur (Tsurumi Chemical Co., Ltd., S
ulfax PMC)-Vulcanization accelerator A: Tetramethylthiuram disulfide (Axel TMT, manufactured by Kawaguchi Chemical Industry Co., Ltd.)-Vulcanization accelerator B: Tetraethyl thiuram disulfide (Ouchi Shinko Chemical Co., Ltd., Noxeller TET) Vulcanization accelerator C: N-cyclohexyl-2-benzothiazyl-sulfenamide (Axel CZ-R, manufactured by Kawaguchi Chemical Industry Co., Ltd.) Vulcanization accelerator A (also serving as a lubricant): stearic acid (manufactured by Kao Corporation, (Lunac S-35)-Vulcanization accelerator B: Zinc oxide (Sakai Chemical Co., Ltd., France No. 1)-Vulcanization accelerator A: Zinc oxide (Zeon Corporation,
Zeonet ZP) However, it was added by the master batch method. -Activator: Organic amine (Acting SL, manufactured by Yoshitomi Pharmaceutical Co., Ltd.)-Plasticizer: Dioctyl phthalate (DOP, manufactured by Daihachi Chemical Industry Co., Ltd.)-Reinforcing agent: Hydrous silica (Nipsil AQ, manufactured by Nippon Silica Industry Co., Ltd.) Wear-reducing material A: carboxyl-modified polyethylene particles (Modic-AP H501, manufactured by Mitsubishi Chemical Corporation) Wear-reducing material B: carboxyl-modified polypropylene particles (Modic-AP P502, manufactured by Mitsubishi Chemical Corporation) Antioxidant A: 4,4′-bis- (α, α-dimethylbenzyl) diphenylamine (Nocrack CD manufactured by Ouchi Shinko Chemical Co., Ltd.) Antioxidant B: 2-mercaptobenzimidazole (Ouchi Shinko Chemical Industry Co., Ltd. Nocrack MB) ・ Antiaging agent C: Special wax (manufactured by Ouchi Shinko Chemical Co., Ltd. G) ・ Lubricant: polyethylene wax (320P, manufactured by Mitsui Chemicals, Inc.) ・ Lubricant: silicone oil (KF-860, manufactured by Shin-Etsu Silicone Co., Ltd.) ・ Coupling agent: γ-mercaptopropyltrimethoxysilane (Shin-Etsu Silicone Co., Ltd.) Next, each step of manufacturing the rubber material composition will be described. (1) First Kneading Step Materials other than the vulcanizing agent and the vulcanization accelerator shown in Table 1 were charged into a Banbury mixer and kneaded at a mixer temperature of 80 ° C. (2) Second Kneading Step The kneaded material was taken out of the Banbury mixer and put into two rolls for rubber kneading. Roll temperature 50 ° C
The vulcanizing agents and vulcanization accelerators shown in Table 1 were added while controlling the temperature, and the operation was repeated until the mixture became uniform. (3) Vulcanizing Step A 2 mm-thick sheet vulcanizing mold was attached to a hot press heated to 170 ° C., and the sheet obtained in the second kneading step was placed thereon. Then, the mixture was heated and pressed for 15 minutes to obtain a vulcanized rubber sheet having a length of 150 mm, a width of 150 mm and a thickness of 2 mm.

The rubber material compositions (Examples 1 to 8 and Comparative Examples 1 and 2) thus produced were subjected to a hardness test, a tensile test, and a friction and wear test. The method of each test is as follows. (A) Hardness test The sheet obtained in the vulcanization step was punched into the shape of a JIS No. 3 test piece, three of which were stacked, and the hardness (spring hardness A scale) was measured based on JIS K6301. (B) Tensile test The JIS No. 3 test piece was subjected to a tensile test using a universal tester, and the tensile strength at break and the tensile elongation at break were measured. (C) Friction and Wear Test A test was carried out based on the method A for testing the sliding and wear of plastics according to JIS K7218 (test piece: rubber material composition disk, mating material: ring). The friction and wear tester is E
FM-III-E (manufactured by Orientec Co., Ltd.) was used.

The wear depth was calculated by measuring the surface shape of the test piece before and after the test with Surfcom (Tokyo Seimitsu Co., Ltd.). Further, the temperature of the partner material during the friction and wear test was also measured. The test conditions are shown below.・ Sliding speed: 1000 mm / sec ・ Sliding distance: 20 km ・ Load: 39.2 N ・ Surface pressure: 19.6 N / cm ²・ Test temperature: room temperature ・ Material: SUJ2 ・ Material roughness: 0.4 μmRa ・ Material Material hardness: HRC 55-62 Table 2 shows the test results.

[0044]

[Table 2]

As can be seen from Table 2, in Example 1 in which the carboxyl-modified nitrile rubber (raw rubber B) was used as the raw rubber, uncarboxylated unmodified nitrile rubber (raw rubber A) was used as the raw rubber. As compared with Comparative Example 1, the amount of wear (wear depth) was small, and the temperature of the mating material was also low. Also, the tensile strength at break was excellent. However, even when the ratio of the acrylonitrile monomer in the carboxyl-modified nitrile rubber was changed (Examples 4 and 6), the results were almost the same.

Further, Example 1 in which carbon black was used as the reinforcing filler was excellent in abrasion resistance, so that it was compared with Comparative Example 2 in which hydrated silica was used as the reinforcing filler.
The amount of wear was very small and the temperature of the mating material was low. In addition,
Regarding the type of carbon black, HAF (Example 1) was slightly superior to FEF (Example 7).

Next, other additives will be considered.
First, in Examples 2 and 8 in which carboxyl-modified polyethylene particles and carboxyl-modified polypropylene particles (both polyolefin particles) as wear improving materials were added to the composition of Example 1, wear resistance and bending resistance were obtained by the wear improving materials. Since the fatigue property was improved, the amount of wear was smaller than in Example 1.

In Examples 3 and 4 in which a lubricant and a lubricating oil were added to the composition of Example 1, the lubricating properties of the rubber material composition were improved by the lubricant and the lubricating oil. Was even lower. Regarding the method of adding zinc oxide, the results were almost the same between direct addition (Example 4) and addition by the master batch method (Example 5).

Next, an oil seal 101 as shown in FIG. 1 was prepared using the rubber material compositions of Examples 1 to 8 and Comparative Examples 1 and 2, and the oil seal 101 was manufactured by Nippon Seiko Co., Ltd. Incorporated into the oil seal unit rotation tester,
The rotation test was performed while exposing to water. The test conditions are as follows. Note that the configuration of the oil seal 101 is the same as that described in the section of the related art, and thus description thereof will be omitted.

-Type of oil seal: Oil seal for railway vehicle axle with inner diameter of 165 mm-Rotation speed: 1000 rpm-Rotation time: continuous rotation for 240 hours-Eccentricity: 0.2 mm TIR-Exposure condition to water: 2 liters of water per minute Was discharged toward the oil seal 101. The water was discharged for 10 seconds.
The stop was performed by repeating a cycle of 20 seconds.

The result of the rotation test of the oil seal 101 is
It is shown in Table 3. The wear amount in Table 3 is shown as a relative value when the wear amount of the oil seal composed of the rubber material composition of Example 1 is set to 1. The sealing performance was evaluated by the amount of water (after the test) contained in the grease applied to the oil seal 101. In addition, when the water content was 1% or less, it was indicated as "good", and the water content was 2 to 5%.
% Is indicated as slightly defective and indicated by Δ, and the case where the water content is 5% or more is indicated as defective by X.

Further, the main lip 1 of the oil seal 101
For the temperature of 04b, a thermocouple was inserted inside the main lip 104b, and the temperature at the time of stable rotation after rotating for 100 hours was measured (unit: ° C.).

[0053]

[Table 3]

As can be seen from Table 3, the oil seals using the rubber material compositions of Examples 1 to 8 have a lower abrasion loss than the oil seals using the rubber material compositions of Comparative Examples 1 and 2. The sealing performance and the temperature of the main lip 104b were both excellent. Next, a hub unit seal 201 as shown in FIG. 2 was prepared using the rubber material compositions of Examples 1 to 8 and Comparative Examples 1 and 2, and the hub unit seal 201 was manufactured by Nippon Seiko Co., Ltd. The rotation test was performed while exposing the unit seal to muddy water by incorporating it into a unit seal rotation tester. The test conditions are as follows.

· Type of hub unit seal: inner diameter 60 m
Hub unit seal of m Rotation speed: 1000 rpm Rotation time: 72 hours Eccentricity: 0.5 mm TIR Exposure condition to muddy water: 2 liters of mud per minute was discharged toward hub unit seal 201. In addition, water discharge was performed by repeating a cycle of water discharge 10 seconds to stop 20 seconds.

Table 4 shows the results of the rotation test of the hub unit seal 201. The wear amount in Table 4 indicates the hub unit seal 201 made of the rubber material composition of Example 1.
Are shown as relative values when the abrasion amount is 1. Also,
The sealing performance was evaluated by the amount of water (after the test) contained in the grease applied to the hub unit seal 201.
In addition, the case where the water content was 1% or less was indicated as "good", the case where the water content was 2 to 5% was indicated as "bad", and the case where the water content was 5% or more was determined as "poor". Indicated by

Further, the hub unit seal 20 on the driving side
As for the temperature of the main lip 201a, a thermocouple was inserted inside the main lip 201a, and the temperature at the time of stable rotation after being rotated for 48 hours was measured (unit: ° C.).

[0058]

[Table 4]

As can be seen from Table 4, the hub unit seal 201 using the rubber material composition of Examples 1 to 8 is different from the hub unit seal using the rubber material composition of Comparative Examples 1 and 2. The wear amount, the sealing property, and the temperature of the main lip 201a were all excellent. In particular, a hub unit seal 2 using the rubber material compositions of Examples 4 to 6
In No. 01, the temperature of the main lip 201a is kept low. The following can be considered as a reason for this.
Since the silicone oil added as the lubricating oil is a terminal amine-modified silicone oil, its amino group reacts with and binds to the main chain of the raw rubber. As a result, the blooming of the silicone oil from the rubber material composition at one time is suppressed, so that the silicone oil is permanently supplied to the surface of the rubber material composition.

As described above, the rubber material composition of the present embodiment uses the carboxyl-modified nitrile rubber as the raw material rubber.
Crosslinking also progresses at the carboxyl group portion present in the molecular structure. Therefore, the crosslink density of the rubber is increased, and the tensile strength, wear resistance, and bending fatigue resistance of the rubber material composition are improved.

Since the rubber material composition of this embodiment contains carbon black, particularly HAF, as a reinforcing filler, it has excellent abrasion resistance as well as white reinforcement such as hydrated silica. Since the thermal conductivity is higher than that of the conductive filler, the temperature of the partner material can be kept low. For this reason, a sealing device such as an oil seal composed of the rubber material composition of the present embodiment has excellent wear resistance, bending fatigue resistance, and lubricity at the contact tip (seal lip). Also, heat generation due to friction is small.

Therefore, the sealing device composed of the rubber material composition of the present embodiment includes a rolling bearing, a linear guide device,
It can be suitably used for a rolling device such as a ball screw.
In particular, a rolling device used in a harsh environment where a large amount of water or dust exists, such as a bearing for a vehicle used for a railway axle, a hub unit bearing for an automobile, a bearing for a steel rolling mill, and the like. It is possible to maintain excellent sealing performance even in such a severe environment and to provide the rolling device with an excellent life.

An example of a rolling device provided with a sealing device made of the rubber material composition of the present embodiment will be described below. First,
The linear guide device will be described with reference to FIG. A slider 2 having a substantially U-shaped cross section is laid on a rectangular guide rail 1 so as to be relatively movable in the axial direction.
The slider 2 includes a slider body 2A and end caps 2B detachably attached to both ends in the axial direction. Upper surface 1a and both side surfaces 1 of guide rail 1
One of the rolling element rolling grooves 3A formed of concave grooves having a substantially arc-shaped cross section is formed in the ridge line portion where b intersects in the axial direction. The other rolling element rolling groove 3B having a substantially semicircular shape is formed in the axial direction.

On the other hand, one of the rolling element rolling grooves 3 of the guide rail 1 is provided at a corner inside the both sleeves 4 of the slider body 2A.
A rolling-element rolling groove (not shown) having a substantially semicircular cross-section facing A is formed, and a cross-section facing the other rolling-element rolling groove 3B of the guide rail 1 is formed at the center of the inner surface of each of the sleeves 4. A substantially semicircular rolling element rolling groove (not shown) is formed.

The rolling element rolling groove 3A of the above-mentioned guide rail 1
A rolling element rolling path (not shown) is formed by 3B and the two rolling element rolling grooves of both sleeves 4. These two rolling element rolling paths form a straight line having a substantially circular cross section. Further, the slider 2 is provided with two rolling element return paths (not shown) each having a through-hole having a circular cross section that penetrates in the axial direction at the upper portion and the lower portion of the thick portion of the sleeve portion 4 of the slider body 2A.

The end cap 2B has a curved path (not shown) for connecting the rolling element rolling path and the rolling element return path parallel to the rolling element rolling path. A circulating path for the rolling elements is formed by the moving element return path and the curved paths at both ends. A large number of rolling elements (not shown) made of, for example, steel balls are provided in the circulation path of the rolling elements.
Is mounted so that it can roll freely.

The slider 2 assembled on the guide rail 1
The rolling element smoothly moves along the guide rail 1 through the rolling of the rolling element in the rolling element rolling path. During the movement, the rolling element circulates endlessly while rolling on the circulation path in the slider 2. The slider 2 is provided with dust-proof contact sealing devices 12 for sealing the opening of a gap formed between the slider 2 and the guide rail 1 at both axial ends (further outside the end cap 2B). The contact sealing device 12 includes the rubber material composition of the present embodiment described above and a metal core (reinforcing member) made of a substantially U-shaped SECC material (galvanized steel sheet) that matches the outer shape of the end cap 2B. This is a sealing device integrally formed by vulcanization bonding.

At least a portion of the contact seal device 12 that is in sliding contact with the guide rail 1 is made of the rubber material composition, and the guide rail 1 is formed so as to seal a gap between the slider 2 and the guide rail 1. The guide rail 1 is formed into a shape that can slide on the upper surface 1a and both side surfaces 1b. However, in order to reliably seal the gap between the guide rail 1 and the inner surface, the inner surface dimension is slightly (0.3-0.
(About 4 mm). However, the core metal is not in contact with the guide rail 1.

The portion (lip) of the rubber surface inside the contact seal device 12 which comes into sliding contact with the guide rail 1 is shown in FIG.
As shown in FIG. 3, three convex portions 20 are formed,
Excellent convexity is exhibited by the convex portion 20.
However, the number of the convex portions 20 is not limited to three, but may be one or two.
The number may be four or four or more. next,
Another example of the linear guide device including the sealing device formed of the rubber material composition of the present embodiment will be described with reference to FIG.

The structure of the linear guide device shown in FIG.
Since it is almost the same as the linear guide device of FIG. 3 described above,
Only different points will be described, and description of the same parts will be omitted. In FIG. 5, the same or corresponding parts as in FIG. 3 are denoted by the same reference numerals as in FIG. On the outer side of the end cap 2B fixed to both ends of the slider body 2A in the axial direction of the slider 2, a reinforcing plate 10, a lubricant supply member 11 made of a lubricant-containing polymer, The contact seal device 12 is fixed in an overlapping state.

Of these, the contact seal device 12 is shown in FIG.
The configuration is exactly the same as that of the contact seal device 12 in the linear guide device. The reinforcing plate 10 is a substantially U-shaped steel plate that matches the outer shape of the end cap 2B. However, the reinforcing plate 10 is not in contact with the guide rail 1. The contact seal device 12 and the reinforcing plate 10
As shown in the perspective view of FIG. 5, the lubricant supply member 11 sandwiched therebetween is also a substantially U-shaped member adapted to the outer shape of the end cap 2B. , The upper surface 1a and both side surfaces 1b of the guide rail 1 according to the cross-sectional shape of the guide rail 1 as in the inner surface of the contact seal device 12.
(The gap between the lubricant supply member 11 and the guide rail 1 is 0 to 0.2 mm).

The composition of the lubricant-containing polymer is as follows: ultra-high molecular weight polyethylene (ultra high molecular weight) 10 wt%, high density polyethylene (relatively low molecular weight) 20 wt%
%, Paraffinic mineral oil 70% by weight. The lubricant supply member 11 was manufactured by injection-molding such a lubricant-containing polymer. The configuration and molding method of the lubricant-containing polymer are not particularly limited, and can be appropriately changed as desired.

The lubricant supply member 11 has a through hole 1 through which a mounting screw passes when fixed to the slider body 2A.
1a, 11b and through hole 1 for mounting grease nipple 7
1c, and tubular sleeves 15A, 15B, 16 are fitted in the through holes 11a, 11b, and 11c, and the grease nipple 7 penetrates the inside of the sleeve 16. The length of these sleeves 15A, 15B, 16 is determined by the lubricant supply member 1
1 or slightly (~ 0.2 mm
Degree) to be longer.

The outer diameters of the sleeves 15A, 15B are larger than the through holes 12a, 12b of the contact seal device 12 and the through holes 10a, 10b of the reinforcing plate 10. By doing so, when the lubricant supply member 11 is sandwiched between the contact sealing device 12 and the reinforcing plate 10 and tightened with the mounting screws 17A and 17B, the pressing force is not applied to the lubricant supply member 11, and Lubricant supply member 11
Does not interfere with the self-contracting action of.

As shown in FIG. 5, which is a perspective view showing the assembled state, the contact sealing device 12, the lubricant supply member 11, and the reinforcing plate 10
A, 17B, through-hole 1 for the screw of the contact seal device 12
2a, 12b, through hole 1 for screw of lubricant supply member 11
1a, 11b, and through hole 10 for screw of reinforcing plate 10
a and 10b, and is screwed to the slider body 2A integrally with the end cap 2B. Note that reference numeral 12c
Is the grease nipple 7 formed on the contact seal device 12.
Reference numeral 10 c denotes a through hole for mounting, and a through hole for mounting the grease nipple 7 formed in the reinforcing plate 10.

In the linear guide device having such a configuration, since the contact seal device 12 seals the opening before and after the gap between the opposing surfaces of the guide rail 1 and the slider 2, the contact seal device 12 suffers from wear and the like. If not, slider 2
Intrusion of water, dust, etc. from before and after can be completely prevented. When the linear guide device is driven, the lubricant supply member 11 also moves while not contacting or in contact with the guide rail 1, and the lubricant gradually seeps out of the lubricant supply member 11 with time. Since the agent supply member 11 is disposed close to the lip portion of the contact sealing device 12 (that is, the inner surface of the contact sealing device 12 that contacts the guide rail 1), the contact sealing device 12 Of the lip portion is stably performed over a long period of time.

The lubricant supply member 11 is connected to the guide rail 1.
The lubricant can be supplied to the lip of the contact seal device 12 through the surface of the guide rail 1 in the case of contact with the lip, so that the supply of the lubricant to the lip is particularly stable. Done in Therefore, the contact sealing device 12
Since the wear of the lip portion is minimized, the sealing property of the contact seal device 12 is maintained for a long time, foreign matter is prevented from entering the inside of the slider body 2A, and the life of the linear guide device itself is extended. It is done.

Further, the lubricant that has oozed out of the lubricant supply member 11 is applied to the guide rail 1, especially to the rolling element rolling grooves 3 A, 3 A.
Via B, it is automatically supplied to the rolling elements rolling in the rolling element rolling grooves 3A, 3B. Due to this self-lubricating property,
Stable and smooth operation is performed over a long period of time. Therefore, good operation with low torque can be continued for a long time without supplying lubricant to the slider 2 from outside.

Further, the lubricant supply member 11 is
Is in contact with the lubricant supply member 11, the lubricant supply member 11 itself self-shrinks as the lubricant seeps out of the lubricant supply member 11. Also, an effect of closely contacting and contacting the surface to be sealed 1 and performing a sealing function and a lubricating function can be obtained.

Further, the lubricant supply member 11 is connected to the reinforcing plate 1.
0, the contact seal device 12 is interposed between the end cap 2B and the contact seal device 12.
The lip portion 2 is unlikely to roll up even when the slider 2 reciprocates, so that leakage of the lubricant inside the slider 2 to the outside is also reduced. In addition, with such a structure, the grease nipple 7 mounting hole may be closed with a blind plug. However, if necessary, the grease nipple 7 may be opened as necessary to supply lubricant such as grease into the slider 2. Is also good.

In this linear guide device,
The lubricant supply member 11 is connected to the reinforcing plate 10 and the contact sealing device 12.
Is fixed to the end face of the end cap 2B in a state sandwiched between the end cap 2B and the end cap 2B, but is not limited to such a structure. For example, the contact seal device 12 is directly attached to the end surface of the end cap 2B, and the lubricant supply member 11 sandwiched between the two reinforcing plates 10 is attached to the end surface of the end cap 2B to which the contact seal device 12 is attached. May be fixed. Even with such a configuration, if the lubricant supply member 11 is disposed close to the lip portion of the contact seal device 12, the same operation and effect can be obtained.

Next, a ball screw provided with a sealing device composed of the rubber material composition of the present embodiment will be described with reference to the drawings. FIG. 6 is a partially cutaway plan view showing the structure of the ball screw of the present example. FIG. 7 is a front view of the ball screw of FIG. 6, and FIG. 8 is a view showing a contact portion between the screw groove 31a of the screw shaft 31 and the contact sealing device 42 in the ball screw of FIG. .

The ball screw has a screw shaft 31 having a spiral screw groove 31a having an arcuate cross section on the outer peripheral surface, and a spiral screw groove facing the screw groove 31a of the screw shaft 31 on the inner surface. A cylindrical ball screw nut 32 screwed into the nut 31
And the screw groove 31a of the screw shaft 31 and the ball screw nut 32
And a number of balls (not shown) that are rollably loaded into a spiral ball rolling space having a substantially circular cross section formed by the screw groove formed by the above.

The cylindrical lubricant supply members 41, 41 made of a lubricant-containing polymer are fitted inside the axially opposite ends of the ball screw nut 32.
Inner diameter surface of the screw shaft 31 contacts only the outer diameter surface of the screw shaft 31 and the screw groove 3
No contact is made with 1a. This lubricant supply member 41
Is composed of two semi-cylindrical members and has a narrow groove on the outer peripheral surface thereof. The garter spring 33 arranged here allows the lubricant supply member 41 to rotate the screw shaft 31 at a constant pressure. It is pressed radially toward the outer circumference. Therefore, even if the inner peripheral surface of the lubricant supply member 41 is worn due to long-term operation, appropriate contact with the screw shaft 31 is always maintained, and good lubrication is ensured.

The composition of the lubricant-containing polymer constituting the lubricant supply member 41 is determined by the linear guide device (FIG. 5).
Is the same as the lubricant supply member 11 in
The present invention is not limited to this, and can be appropriately changed.
The contact seal devices 42 and 42 are press-fitted to the outside of the lubricant supply member 41 in the axial direction. The contact sealing device 42 includes a metal or plastic core metal (reinforcing member) 42b, a disk-shaped seal body 42c including the core metal 42b, and a substantially conical shape extending inward from the seal body 42c ( Seal piece 4 having a shape inclined to the left in each figure)
2d.

The seal piece 42d has an opening 42a at the center corresponding to the sectional shape of the screw shaft 31 and having a slightly smaller inner diameter. The seal body 42c for fixing the outer periphery to the ball screw nut 32 (not shown in FIG. 7) and the seal piece 42d are integrally formed of the rubber material composition of the present embodiment described above. Then, the integral portion made of the rubber material composition and the core metal 42b are integrated by vulcanization bonding.

The core 42b has a circular outer periphery, but has an inner periphery similar to the opening 42a. That is, as shown in FIG. The width D2 is small. Therefore, the core metal 42
distance D from the inner periphery of b to the inner periphery of seal body 42c
0 and the distance D3 from the inner peripheral edge of the seal main body 42c to the inner peripheral edge of the seal piece 42d can be made constant over the entire circumference, whereby the contact sealing device 42 when contacting the screw shaft 31 can be set. Can be made substantially constant.

FIG. 9 shows that the contact seal device 42 is
FIG. 5 is a partially enlarged view showing a state in which it is deformed by abutting on. The contact seal device 42 shown by the solid line is in a state where it is not in contact with the screw shaft 31, and the contact seal device 42 shown in a two-dot chain line is in a state where it is in contact with the screw shaft 31 and is deformed. The contact portion (lip portion) of the seal piece 42d of the contact seal device 42 with the screw shaft 31 is formed on the outer diameter surface of the screw shaft 31 and the screw groove 3.
1a is always interference (actually, the gap is kept at 0 or less by deformation).

As can be seen from FIG. 9, the contact sealing device 4
Even if 2 is in contact with any part of the screw shaft 31 (the outer diameter surface of the screw shaft 31 or the screw groove 31a), the bending direction of the seal piece 42d can be predicted based on its shape.
Therefore, it is possible to design the shape of the sealing piece 42d so that the sealing performance is maximized. The configuration, shape, and the like of such a contact seal device 42 are not limited to this example.

When the ball screw nut 32 is moved, the contact seal device 42 slides on the screw shaft 31 to securely seal the inside.
Foreign matters such as water and dust enter through the opening of the gap between the ball screw nut 32 and the leakage of the lubricant to the outside of the ball screw nut 32. Therefore, a longer life of the ball screw is achieved. In addition, since the contact seal device 42 is supplied with the lubricant that has oozed from the lubricant supply member 41, the lip portion is less likely to be worn and has excellent sealing properties.

In this embodiment, a rolling bearing, a linear guide device, and a ball screw have been described as examples of rolling devices. However, the rubber material composition of the present invention can be used in various other types of rolling devices. The invention can be applied to an apparatus, and the present invention is not limited to this embodiment.

[0092]

As described above, since the rubber material composition of the present invention comprises a carboxylated acrylonitrile-butadiene rubber and carbon black, it has excellent abrasion resistance and generates little heat due to friction. Therefore, if the sealing device of the rolling device used for grease lubrication in a harsh environment where a large amount of water or dust is present is configured with the rubber material composition of the present invention, even in such a harsh environment. An excellent life can be imparted to the rolling device while maintaining excellent sealing properties.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the structure of a bearing provided with an oil seal composed of a rubber material composition of the present invention.

FIG. 2 is a longitudinal sectional view showing the structure of a hub unit seal made of the rubber material composition of the present invention.

FIG. 3 is a perspective view of a linear guide device provided with a contact seal device made of the rubber material composition of the present invention.

FIG. 4 is a partially enlarged view showing a shape of a lip portion of the contact seal device of the linear guide device of FIG. 3;

FIG. 5 is a perspective view showing an attached state of each member at an end of another linear guide device provided with a contact seal device made of the rubber material composition of the present invention.

FIG. 6 is a plan view of a ball screw provided with a contact sealing device composed of the rubber material composition of the present invention.

FIG. 7 is a front view of the ball screw of FIG. 6;

8 is a view showing a contact portion between a thread groove of the ball screw of FIG. 6 and a contact sealing device.

FIG. 9 is an enlarged view showing a state in which the contact sealing device is in contact with a screw groove of a screw shaft.

[Explanation of symbols]

 101 oil seal 104b main lip 201 hub unit seal 201a main lip

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shunichi Yabe 1-50, Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 4J002 AC071 AC101 DA036 FD016 GM05

Claims (1)

[Claims] 1. A rubber material composition comprising 100 parts by weight of carboxylated acrylonitrile butadiene rubber and 20 to 90 parts by weight of carbon black.