JP2002302571A - Rubber material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber material composition having excellent abrasion resistance and slight heat generation by friction, suitably used for a sealing device for a rolling apparatus to be used in grease lubrication under a severe condition in which a large amount of water and dust exist. SOLUTION: This rubber material composition is obtained by a structure having carboxylated acrylonitrile butadiene rubber added with a vulcanization- based additive, an antioxidant, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber suitable for use in a sealing device provided in a rolling device such as a rolling bearing (a hub unit bearing for a vehicle, a bearing for a railway vehicle, etc.), a linear guide device, and a ball screw. The present invention relates to a material composition, and more particularly to a rubber material composition suitably used for a sealing device of a rolling device used for grease lubrication under a severe environment where a large amount of water and dust are present.

[0002]

2. Description of the Related Art Conventionally, a rolling device provided with a sealing device such as a hub unit 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). Even when used in such a severe environment, a rubber material composition in which an additive is appropriately blended with nitrile rubber or the like has been used. A sealing device using such a rubber material composition for an elastic member has a sufficient sealing performance even in the case of grease lubrication in an environment with little water or dust, that is, in a clean environment.

However, since a hub unit bearing for an automobile and a bearing for a vehicle used for an axle of a railway are used outdoors, they are exposed to a large amount of water (rainwater, muddy water, etc.) and dust to lubricate 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] Next, a hub unit seal provided in a hub unit bearing for an automobile will be described as an example of a sealing device provided in a rolling device used in a severe environment as described above. As such a hub unit seal, for example, there is a seal as shown in FIG. The hub unit seal 100 includes a core 105 and a slinger 106.
And an elastic member 107. The elastic member 107 is generally made of a nitrile rubber composition.

[0005]

The hub unit seal 100 as described above is often used for a long period of time in a harsh environment such as exposure to muddy water. Therefore, the seal lip 1 of the slinger 106 and the elastic member 107
In some cases, heat generated between the bearings 14, 115, and 116 deteriorates the grease of the bearing and shortens the life of the bearing.

Further, if the lubrication of the seal lips 114, 115, 116 becomes insufficient due to exposure to water, the wear of the seal lips 114, 115, 116 is accelerated, and the sealing performance is reduced at an early stage. When the seal lips 114, 115, and 116 are worn out for a long time or when used for a long period of time, water or dust may enter the bearing, and the life of the bearing may be shortened.

As described above, the conventional hub unit seal 100 in which the elastic member 107 is made of the nitrile rubber composition is used.
Under the severe operating conditions as described above, the seal lips 114 and 11 of the slinger 106 and the elastic member 107 are used.
Sliding lip 114,11 by sliding contact with 5,116
5, 116 are easily worn out early, and the seal lip 11
4, 115, 116 and the slinger 106 have deteriorated sealing performance, so that the original function of the hub unit seal is often not sufficiently exhibited.

In addition, even before the abrasion progresses, the grease deteriorates due to frictional heat, and similarly, the function of the hub unit seal 100 is often not sufficiently exhibited. Therefore, the present invention solves the problems of the prior art as described above, and is a rubber material composition having excellent abrasion resistance and low heat generation due to friction, in a severe environment where a large amount of water and dust exist. It is an object of the present invention to provide a rubber material composition suitably used for a sealing device of a rolling device used for grease lubrication.

[0009]

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 is characterized by having a carboxylated acrylonitrile butadiene rubber. With such a configuration, the rubber material composition has a high crosslinking density, and thus has excellent wear resistance and bending fatigue resistance. Therefore,
If the sealing device of the rolling device used in grease lubrication in a harsh environment where a large amount of water or dust is present is made of the rubber material composition of the present invention, it is excellent even in such a harsh environment. An excellent life can be provided to the rolling device while maintaining the sealing property.

The rubber material composition of the present invention is described below.
This 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. 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. If necessary, wear modifiers, vulcanizing additives, reinforcing fillers, anti-aging agents, lubricants, lubricating oils,
And various additives such as processing aids may be further added.

The carboxylated acrylonitrile-butadiene rubber has a structure in which ordinary acrylonitrile-butadiene rubber has a carboxyl group. Then, crosslinking occurs in the rubber material composition due to the carboxyl group, the crosslinking density increases, and the tensile strength of the rubber material composition improves. As a result, the wear resistance and bending fatigue resistance of the rubber material composition are improved.

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 the production by emulsion polymerization or the like. Can be obtained by further adding acrylic acid, methacrylic acid, or the like, and copolymerizing.

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.
Range. However, each monomer does not polymerize according to the added weight ratio (that is, the weight ratio of the added monomer is different from the composition ratio of the obtained polymer), and the carboxyl group-containing monomer Since the polymer is difficult to polymerize, 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 ^-Fourmore than ephr
Preferably 2 × 10^-3~ 5 × 10^-2ephr
More preferably, it is within the range. Acid equivalent of 1 × 10^-Foure
If the amount is less than phr, the normal (carboxylated
Not) Crosslinked compared to acrylonitrile butadiene rubber
Since the density hardly changes, the tensile strength of the rubber material composition
Little improvement in strength, wear resistance, etc. is seen. This
To make such inconveniences less likely to occur, the acid equivalent should be 2
× 10^-3It is more preferably at least ephr.

On the other hand, if the acid equivalent exceeds 5 × 10 ^-2 ephr, the amount of carboxyl groups increases and the crosslink 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 possibility of scorch increases. When ordinary acrylonitrile-butadiene rubber is used as a raw material rubber, when the tensile elongation at break is about 200%, the tensile strength is about 15 to 20 MPa. On the other hand, when the carboxylated acrylonitrile butadiene rubber is used as the raw material rubber, the tensile elongation at break is 20%.
When it is about 0%, the tensile strength becomes 25 MPa or more.

This is because the crosslinking reaction proceeds in the carboxyl group portion in addition to the double bond portion due to butadiene and the crosslinking density increases, so that the tensile strength is higher than when ordinary acrylonitrile butadiene rubber is used as the raw material rubber. This is considered to be because the wear resistance and the bending fatigue resistance are improved. 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.

The above 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 types of carboxylated acrylonitrile-butadiene rubber similar to ordinary acrylonitrile-butadiene rubber. Depending on the content of acrylonitrile, low nitrile, medium nitrile,
There are medium and high nitriles, high nitriles, and extremely high nitriles. In consideration of heat resistance and oil resistance, medium nitriles, medium and high nitriles, and high nitriles are preferable, and the content of acrylonitrile is preferably 20 to 40%.

When such a rubber material composition is used in a sealing device such as a hub unit seal, a vulcanizing additive,
Anti-aging agents and the like are added as essential components, but in some cases, reinforcing fillers, wear improvers, lubricants, lubricating oils,
And various additives such as processing aids. Examples of the reinforcing filler include carbon black and white filler. As carbon black, specifically,
ISAF (Intermediate Super Abrasion Furnace blac
k), MAF (Medium Abrasion Furnace black), S
RF (Semi-Reinforcing Furnace black), GPF (Ge
neral Purpose Furnace black), FT (Fine Thermal
Furnace black), MT (Medium Thermal Furnace bla)
ck), HAF (High Abrasion Furnace black), FE
F (Fast Extruding Furnace black) and the like can be exemplified, but in order to improve wear resistance, HAF and FEF having high reinforcing properties are more preferable.

Specific examples of the white filler include hydrated silica, clay, talc, calcium carbonate, diatomaceous earth, wollastonite and the like. In addition, you may mix and use carbon black and a white filler.
When such a reinforcing filler is used, the abrasion resistance of the elastic member constituting the sealing device (the contact tip (seal lip portion) in sliding contact with a mating member such as a shaft) is improved, and as a result, the elastic member and the mating member are improved. The sealing property between the materials is improved.

In the case of carbon black, the amount of the reinforcing filler is preferably 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, and the inherent rubber elasticity decreases. .

In the case of a white filler, 20 parts by weight per 100 parts by weight of carboxylated acrylonitrile butadiene rubber is used.
It is preferable to set it to 150 parts by weight. When the amount is less than 20 parts by weight, sufficient reinforcing properties are not exhibited, and when the amount is more than 150 parts by weight, the hardness of the rubber material composition increases and the elongation decreases, and the inherent rubber elasticity decreases. .

When carbon black and a white filler are mixed, the amount is preferably 20 to 200 parts by weight based on 100 parts by weight of the carboxylated acrylonitrile butadiene rubber. Of these, carbon black is 10 to 90 parts by weight, and white filler is 10 to 110 parts by weight. When the amount of the reinforcing filler is less than 20 parts by weight, sufficient reinforcing properties are not exhibited, and when the amount is more than 200 parts by weight, the hardness of the rubber material composition increases and the elongation decreases. Will decrease.

Next, the wear modifier will be described. Examples of the wear improver include polyolefin particles and spherical carbon fine particles. Among these, specific examples of the polyolefin particles include polyethylene and polypropylene particles, and more preferably, carboxyl-modified polyethylene (maleic anhydride-modified polyethylene) and carboxyl-modified polypropylene (maleic anhydride-modified polypropylene) particles. Is raised.

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.

Next, a lubricant for improving lubricity will be described. Examples of the lubricant include wax having a melting point of 75 to 140 ° C. (low melting point fat). As a specific example,
Paraffin wax, polyethylene wax, montan wax, carnauba wax having the above melting point range,
Ester wax, stearoamide, oxystearamide, erucylamide, laurylamide, palmitylamide, behenamide, methylolamide, ethylenebisoleylamide, stearyloleylamide, and the like, among which polyethylene wax is most preferred. When 5 to 30 parts by weight of such a lubricant is added to 100 parts by weight of carboxylated acrylonitrile butadiene rubber, the lubricity of the rubber material composition is improved. If it is less than 5 parts by weight, sufficient lubricity cannot be obtained, and if it is more than 30 parts by weight, sufficient tensile strength and elongation cannot be obtained and rubber elasticity decreases.

As the lubricating oil, ether oils, silicone oils, poly α-olefin oils,
Fluorinated oils and fluorinated surfactants are exemplified. Among these, silicone-based oils are more preferred, and modified silicone oils having functional groups at the terminals and side chains are particularly preferred. Since the functional group of the terminal or side chain reacts with the main chain of the carboxylated acrylonitrile-butadiene rubber, the oil is prevented from blooming on the surface of the rubber material composition at once, and gradually blooms. It is believed that the oil will be permanently supplied to the surface of the rubber material composition.

Since the lubricating oil is in a liquid state and easily blooms on the surface of the rubber material composition, a lubricating effect is easily exerted by adding a small amount of the lubricating oil than the above-mentioned lubricant. When 2 to 30 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. When the amount is less than 2 parts by weight, sufficient lubricity cannot be obtained, and when the amount is more than 30 parts by weight, poor dispersion of additives tends to occur during processing of the rubber material composition.

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-based vulcanizing agent is used, guanidine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and xanthate-based vulcanizing agents are used. 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. However, carboxylated acrylonitrile-butadiene rubber is liable to undergo early vulcanization due to 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.

Next, an anti-aging agent for preventing oxidative deterioration will be described. Examples of the antioxidant include amine-ketone condensation products, aromatic secondary amines, monophenol derivatives, bis or polyphenol derivatives, hydroquinone derivatives, sulfur antioxidants, and phosphorus antioxidants. Among them, the amine-ketone condensation product system 2,
2,4-trimethyl-1,2-dihydroquinoline polymer, condensation product of diphenylamine and acetone, aromatic secondary amine N, N′-di-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.

Further, 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. When the amount is less than 0.5 part by weight, the effect of preventing cracks due to the action of ozone is hardly obtained, and when the amount is more than 2 parts by weight,
Unnecessary waxes bloom on the surface of the rubber material composition, which may cause a problem in workability.

Further, when it is necessary to improve the moldability, a plasticizer is appropriately added as a processing aid in addition to the above 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. Next, physical properties will be described. The hardness of the rubber material composition is affected by the amount of a reinforcing filler, an abrasion improver, and the like added thereto. However, the sealability and followability when applied to a sealing device such as a hub unit seal comply with JIS AK6301. In the described spring hardness A scale, a range of 50 to 90 is preferable.

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. Also,
When the hardness exceeds 90, the rubber elasticity is reduced as described above, so that the sealing property and followability of the contact tip in the rotating motion are reduced, and the life of the rolling device is extended when used in an environment with a lot of dust. It may decrease.

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.

[0040]

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 of the present embodiment comprises a raw rubber, a reinforcing filler,
And various additives were blended at the ratios shown in Tables 1 and 2 and were manufactured by the following steps.

[0041]

[Table 1]

[0042]

[Table 2]

First, the various materials used (those described in Tables 1 and 2) will be described. Raw rubber A: carboxylated medium-high nitrile rubber (Nipol DN631 manufactured by Zeon Corporation), acrylonitrile monomer ratio: 33.5% Raw rubber B: medium-high nitrile rubber (manufactured by JSR Corporation)
JSR NBR N230S), acrylonitrile monomer ratio: 35% ・ Carbon black (reinforcing filler): carbon black HAF (manufactured by Mitsubishi Chemical Corporation, Diablack H) ・ Silica (white filler): hydrous silica ( Nip Seal AQ, manufactured by Nippon Silica Industry Co., Ltd.-Clay (white filler): Kaolin clay (ST-309, manufactured by Shiraishi Calcium Co., Ltd.)-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 (Nouchira TET, manufactured by Ouchi Shinko Chemical Co., Ltd.) 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 C: 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: Adipic acid-based polyester (PN-350, manufactured by Asahi Denka Co., Ltd.)-Wear modifier A: Carboxyl-modified polyethylene particles (Mitsubishi Chemical Corporation) -Modifier-AP H501)-Wear modifier B: Carboxyl-modified polypropylene particles (Modic-AP P502-manufactured by Mitsubishi Chemical Corporation)-Antioxidant A: 4,4'-bis (α, α-dimethylbenzyl) diphenylamine (Ouchi Shinko Chemical Co., Ltd., Nocrack CD) ・ Antiaging agent B: 2-mercaptobenzimidazole (Ouchi Shinko Chemical Co., Ltd., Nocrack MB) ・ Antiaging agent C: Special wax (Ouchi Shinko Chemical) -Lubricating oil: Silicone oil (KF-, manufactured by Shin-Etsu Silicone Co., Ltd.) 860) Coupling agent: γ-mercaptopropyltrimethoxysilane (KBM803, manufactured by Shin-Etsu Silicone Co., Ltd.) Next, each step of producing the rubber material composition will be described. (1) First Kneading Step Materials other than the vulcanizing agent and the vulcanization accelerator shown in Tables 1 and 2 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 Tables 1 and 2 were added while controlling the temperature, and the operation was repeated until the mixture became uniform. (3) Vulcanizing Step A sheet vulcanizing mold for a thickness of 2 mm was mounted on 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 to 3) thus produced were subjected to a hardness test and a tensile 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.

Tables 3 and 4 show the test results.

[0046]

[Table 3]

[0047]

[Table 4]

As can be seen from Tables 3 and 4, Examples 1 to 8 in which carboxylated acrylonitrile butadiene rubber was used as the raw material rubber were compared with Comparative Examples 1 to 3 in which ordinary non-carboxylated acrylonitrile butadiene rubber was used. In comparison, the tensile strength at break was excellent, and the hardness and tensile elongation at break were equal or higher. Next, a hub unit seal 100 as shown in FIG. 1 was prepared using the rubber material compositions of Examples 1 to 8 and Comparative Examples 1 to 3 (the elastic member 107 of the hub unit seal 100 was replaced with the rubber material composition). Object).

Hereinafter, the structure of the hub unit seal 100 will be described in detail. The hub unit seal 100 includes a metal core 105, a slinger 106, and an elastic member 107. Among them, the core metal 105 is integrally formed by performing a punching process such as a press process and a plastic process on a metal plate such as a low carbon steel plate. Such a core metal 105 includes an outer cylindrical portion 109 that can be fitted and fixed on the inner peripheral surface of an end portion of an outer ring that constitutes a rolling bearing (not shown), and an axial inner edge of the outer cylindrical portion 109. (Left edge in FIG. 1)
And an inner annular portion 110 bent inward in the radial direction from the inside, and has an annular shape having a substantially L-shaped cross section.

The slinger 106 is integrally formed by performing a punching process such as a press process and a plastic process on a metal plate having excellent corrosion resistance such as a stainless steel plate. Such a slinger 106 includes an inner cylindrical portion 112 that can be externally fitted and fixed to an outer peripheral surface of an end portion of an inner ring that constitutes the rolling bearing, and an axial outer end edge of the inner cylindrical portion 112 (the right end in FIG. 1). And an outer annular portion 113 bent radially outward from the edge) to form an annular shape having a substantially L-shaped cross section.

Further, the elastic member 107 is made of the rubber material composition having elasticity, and has three seal lips 114, 115, 116 on the outside, the middle, and the inside. The base end is fixed to the cored bar 105. The tip of the outermost outer seal lip 114 is in sliding contact with the inner surface of the outer annular portion 113 constituting the slinger 106, and the tips of the intermediate seal lip 115 and the inner seal lip 116 are the inner cylindrical portion constituting the slinger 106. And 112 is in sliding contact with the outer peripheral surface. from these things,
Grease is prevented from leaking from the inside, and dust, water, muddy water and the like from outside are prevented from entering the inside of the rolling bearing.

The hub unit seal 100 was assembled in a hub unit seal unit rotation tester manufactured by Nippon Seiko Co., Ltd., and a rotation test was performed while being exposed to muddy water. The test conditions are as follows. -Type of hub unit seal: hub unit seal with an inner diameter of 60 mm-Rotation speed: 1000 rpm-Rotation time: 72 hours-Eccentricity: 0.5 mm TIR-Exposure conditions to muddy water: 2 liters of mud per minute toward the hub unit seal Water was released. In addition, water discharge is water discharge 10
This was done by repeating the cycle of seconds-stop 20 seconds.

Tables 5 and 6 show the results of the rotation test of the hub unit seal. The wear amounts in Tables 5 and 6 are relative values when the wear amount of the hub unit seal (seal lip) made of the rubber material composition of Example 1 is set to 1. The sealing performance was evaluated by the amount of moisture (after the test) contained in the grease applied to the hub unit seal. 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 temperature of the seal lip of the hub unit seal on the drive side was measured after inserting a thermocouple inside the seal lip and rotating the seal lip for 24 hours during stable rotation (unit: ° C.). .

[0055]

[Table 5]

[0056]

[Table 6]

As can be seen from Tables 5 and 6, the hub unit seals composed of the rubber material compositions of Examples 1 to 8 using carboxylated acrylonitrile butadiene rubber as the raw material rubber were obtained from ordinary non-carboxylated acrylonitrile. Comparative Examples 1 and 2 using butadiene rubber
The wear amount of the seal lip was smaller than that of the hub unit seal made of the rubber material composition of No. 3.

The hub unit seals using the rubber material compositions of Examples 1 to 8 had a very low water content in the grease, while the rubber material compositions of Comparative Examples 1 to 3 were used. The hub unit seal had a large amount of water in the grease. As described above, hub unit seals using the rubber material compositions of Examples 1 to 8 were also excellent in sealing performance.

Next, the effect of the additive will be described. First, hub unit seals using the rubber material compositions of Examples 1, 2, and 5 containing carboxyl-modified polyethylene particles and carboxyl-modified polypropylene particles as wear improvers have abrasion resistance due to the action of the wear improver. Since the bending fatigue resistance is improved, the abrasion loss of the seal lip was further reduced as compared with the hub unit seal using the rubber material composition of another example.

The hub unit seal using the rubber material compositions of Examples 3 and 6 containing a modified silicone oil as a lubricating oil improves the lubricity of the rubber material composition by the action of the lubricating oil. Because, compared with the hub unit seal using the rubber material composition of other examples,
Heat generation is suppressed and the temperature of the seal lip is low.

As described above, the rubber material composition of the present embodiment uses the carboxylated acrylonitrile-butadiene rubber as the raw material rubber, so that it exists in the molecular structure in addition to the usual crosslinking with the vulcanizing agent. Crosslinking also proceeds at the carboxyl group. Therefore, the crosslink density of the rubber is increased, and the tensile strength, abrasion resistance,
Bending fatigue resistance is improved.

Therefore, a sealing device such as a hub unit seal made of the rubber material composition of the present embodiment can be suitably used for a rolling device such as a rolling bearing, a linear guide device, and a ball screw. In particular, the present invention is suitable for a rolling device used in a harsh environment where a large amount of water or dust is present, such as a bearing for a railway vehicle or a hub unit bearing for an automobile. In this case, the excellent sealing performance can be maintained, and the rolling device can be provided 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 larger than the dimension in contact with the surface of the guide rail 1 (0.1-0.
(About 2 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 is in 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. Note that the structure of the linear guide device of FIG. 4 is substantially the same as that of the linear guide device of FIG. 2 described above, and therefore only different points will be described, and description of the same parts will be omitted. In FIG. 4, the same or corresponding parts as in FIG. 2 are denoted by the same reference numerals as in FIG.

Further, 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 1 is provided from the side close to the end cap 2B.
0, a lubricant supply member 11 made of a lubricant-containing polymer, and a contact sealing device 12 are fixed in an overlapping state. Of these, the contact seal device 12 has exactly the same configuration as the contact seal device 12 in the linear guide device of FIG.

The reinforcing plate 10 is provided with the end cap 2B.
It is a substantially U-shaped steel plate adapted to the outer shape of. However, the reinforcing plate 10 is not in contact with the guide rail 1. The lubricant supply member 11 sandwiched between the contact seal device 12 and the reinforcing plate 10 is also a substantially U-shaped member adapted to the outer shape of the end cap 2B as shown in a perspective view of FIG. Like the inner surface of the contact seal device 12, the U-shaped inner surface does not contact or at least partially slides on the upper surface 1 a and both side surfaces 1 b of the guide rail 1 according to the cross-sectional shape of the guide rail 1. (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 is formed, and tubular sleeves 15A, 15B, 16 are fitted into the through holes 11a, 11b, and 11c, and the grease nipple 7 passes through 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. 4, 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. 5 is a partially broken plan view showing the structure of the ball screw of this example. FIG. 6 is a front view of the ball screw of FIG. 5, and FIG. 7 is a diagram 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. 4).
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. 6) 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 metal 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. Can be made substantially constant.

FIG. 8 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. 8, 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 the 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 matter such as water and dust enters 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 seeps out of 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 the rolling device. 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, the rubber material composition of the present invention has a high crosslink density due to the presence of the carboxylated acrylonitrile butadiene rubber, and as a result, has excellent abrasion resistance and flex fatigue resistance. I have. In addition, heat generation due to friction is small.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing the structure of a hub unit seal made of a rubber material composition of the present invention.

FIG. 2 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. 3 is a partially enlarged view showing a shape of a lip portion of the contact seal device of the linear guide device of FIG. 2;

FIG. 4 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. 5 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. 6 is a front view of the ball screw of FIG. 5;

FIG. 7 is a view showing a contact portion between a thread groove of the ball screw of FIG. 5 and a contact sealing device.

FIG. 8 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]

 REFERENCE SIGNS LIST 100 hub unit seal 107 elastic member 114 outer seal lip 115 intermediate seal lip 116 inner seal lip

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takahiko Uchiyama 1-5-150 Kugenuma Shinmei, Fujisawa-shi, Kanagawa Japan Seiko Co., Ltd. F-term (reference) 4J002 AC101 CC252 CM022 DA046 EK036 EK046 EK056 EK066 EN077 EN107 EV076 EV146 EV346 FD010 FD020 FD070 FD072 FD077 FD146 FD150 FD170 GJ02 GM00 GM05 GN00

Claims (1)

[Claims] 1. A rubber material composition comprising a carboxylated acrylonitrile butadiene rubber.