JP2002275312A - Rubber material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber material composition which is excellent in abrasion resistance and is suitably used for a sealing device of a rolling apparatus which is used under grease lubrication under such severe conditions that a large amount of water or dust is present. SOLUTION: This composition contains an acrylonitrile-butadiene rubber and a carboxy-modified polyolefin.

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. For this reason, the contact tip that comes into sliding contact with the shaft is worn, and the sealing performance is reduced, and inconveniences such as intrusion of water and dust into the bearing occur. As a result, the life of the bearing may be shortened.

[0004] Further, 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, scale, etc. is present and is exposed to a large amount of cooling water. It was worse than the hub unit bearings for automobiles and the bearings for railway vehicles. Therefore, the same problem as described above may occur. next,
As an example of a sealing device provided in a rolling device used in a severe environment as described above, a hub unit seal provided in an automobile hub unit bearing will be described.

[0005] As such a hub unit seal,
For example, there is one shown in FIG. The hub unit seal 100 includes a metal core 105, a slinger 106, and an elastic member 107. The elastic member 107 is generally made of a nitrile rubber composition.

[0006]

The hub unit seal 100 as described above is often used for a long period of time in an adverse environment such as exposure to muddy water. Accordingly, the seal lips 114, 1 of the slinger 106 and the elastic member 107
In some cases, the heat generated between the bearings 15 and 116 causes the grease of the bearing to deteriorate, thereby shortening 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.

Therefore, the present invention solves the above-mentioned problems of the prior art, and is a rubber material composition having excellent wear resistance, which can be used under 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 lubrication.

[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 has an acrylonitrile-butadiene rubber and a carboxyl-modified polyolefin. Hereinafter, for the rubber material composition of the present invention,
This will be described in detail.

[0011] The rubber material composition of the present invention has acrylonitrile butadiene rubber as a raw rubber and carboxy-modified polyolefin as a wear improver. 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, various additives such as a vulcanizing additive, a reinforcing filler, an antioxidant, a lubricant, a lubricating oil, and a processing aid may be further added.

Acrylonitrile butadiene rubber, which is a raw material rubber, has several types, and is classified into low nitrile, medium nitrile, medium high nitrile, high nitrile, and extremely high nitrile according to the content of acrylonitrile from the lower one. However, in consideration of heat resistance and oil resistance, medium nitrile, medium-high nitrile, and high nitrile are preferable. In this case, the content of acrylonitrile is 20 to 40%.

Typical examples of the carboxy-modified polyolefin as a wear improver include carboxy-modified polyethylene and carboxy-modified polypropylene. These are carboxy-modified (maleic anhydride-modified) polyolefins such as polyethylene and polypropylene.
It was done. When polyolefins such as polyethylene and polypropylene are carboxy-modified, they are easily adsorbed to various rubbers and oxides by carboxyl groups in the structure. It is considered that this improves the mechanical strength such as tensile strength, wear resistance and bending fatigue resistance.

The amount of the carboxy-modified polyolefin relative to the acrylonitrile-butadiene rubber is preferably 10 to 60 parts by weight based on 100 parts by weight of the acrylonitrile-butadiene rubber in view of the balance between the abrasion resistance and other physical properties of the rubber material composition. . If the amount is less than 10 parts by weight, the effect of improving the wear resistance is low, and if it is more than 60 parts by weight, the hardness of the rubber material composition is improved and the tensile elongation at break is reduced, so that the rubber elasticity is reduced.

When such a rubber material composition is used in a sealing device such as a hub unit seal, a vulcanizing additive,
The anti-aging agent and the like are added as essential components, but depending on the case, various additives such as a reinforcing filler, a lubricant, a lubricating oil, and a processing aid may be added. Examples of the reinforcing filler include carbon black and white filler.
As the carbon black, specifically, ISAF (In
termediate Super Abrasion Furnace black), MAF
(Medium Abrasion Furnace black), SRF (Semi-R
einforcing Furnace black), GPF (General Purpos)
e Furnace black), FT (Fine Thermal Furnace bla
ck), MT (Medium Thermal Furnace black), HAF
(High Abrasion Furnace black), FEF (Fast Ext
ruding Furnace black), etc.
In order to improve wear resistance, HAF, which has high reinforcement,
FEF is more preferred.

Specific examples of the white filler include hydrated silica, clay, talc, calcium carbonate, diatomaceous earth, wollastonite and the like. Note that carbon black and a white filler may be used as a mixture.
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 acrylonitrile butadiene rubber. 2
If the amount is less than 0 parts by weight, sufficient reinforcing properties are not exhibited, and if the amount 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, it is preferably 20 to 150 parts by weight based on 100 parts by weight of acrylonitrile butadiene rubber. 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. . Furthermore, 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 acrylonitrile butadiene rubber. Among them, carbon black is 10 to 90 parts by weight, and white filler is 10 to 110 parts by weight. 20 reinforcing fillers
If it is less than parts by weight, sufficient reinforcing properties are not expressed, and
If it exceeds 200 parts by weight, the hardness of the rubber material composition increases and the elongation decreases, and the inherent rubber elasticity decreases.

Next, as a lubricant for improving lubricity, wax having a melting point of 75 to 140 ° C. (low melting point fat) is used. 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 30 parts by weight with respect to 0 parts by weight improves the lubricity of the rubber material composition. 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.

The lubricating oils include ether oils, silicone oils, poly α-olefin oils,
Fluorine oil, fluorinated surfactant and the like can be mentioned. Among these, silicone-based oils are more preferred, and modified silicone oils having a functional group at the terminal are particularly preferred.
Since the terminal functional group reacts with the main chain of the acrylonitrile-butadiene rubber, the oil is prevented from blooming on the surface of the rubber material composition at one time, and gradually blooms. It is believed that it will be permanently supplied to the surface of the object.

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 smaller amount than the above-mentioned lubricant. Such lubricating oil is used in an amount of 2 to 3 parts per 100 parts by weight of acrylonitrile butadiene rubber.
Addition of 0 parts by weight improves the lubricity of the rubber material composition. If the amount is less than 2 parts by weight, sufficient lubricity cannot be obtained, and 3
If the amount is more than 0 parts by weight, poor dispersion of the additive is likely to occur during processing of the rubber material composition.

Incidentally, spherical carbon fine particles (glassy carbon, spherical graphite) may be used together with the carboxy-modified polyolefin as a wear improver. The spherical carbon fine particles
Phenol / formaldehyde resin in nitrogen 800 ~
It is carbonized and fired at a temperature of 2000 ° C., and has an average particle size of about 2 to 40 μm. Specifically, Bell Pearl C (registered trademark) manufactured by Kanebo Co., Ltd. is preferable.

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 5 to 2 parts by weight based on 100 parts by weight of acrylonitrile butadiene rubber.
0 parts by weight is preferred. If the amount is less than 5 parts by weight, the load cannot be sufficiently received, and if it exceeds 20 parts by weight, the abrasion resistance of the rubber material composition decreases.

Next, the vulcanizing additive 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, 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. Antioxidants that prevent oxidative deterioration include amine-ketone condensation products, aromatic secondary amines, monophenol derivatives, bis or polyphenol derivatives, hydroquinone derivatives, sulfur antioxidants, and phosphorus antiaging agents. Agents 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,
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-mentioned additives. However, if there is no particular problem in molding, it may not be added. When added, 3 to 20 parts by weight of acrylonitrile butadiene rubber is used.
It may be added in parts by weight, and if added more than necessary, the rubber material composition may soften and bleed out without being completely mixed.

Specific examples of the plasticizer include phthalic acid diester such as dioctyl phthalate, polyester-based plasticizer, polyether-based plasticizer, polyetherester-based plasticizer, 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 modifier, and the like, but is described in JIS K6301 because of the sealing properties and followability when applied to a sealing device such as a hub unit 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. 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. In order to reduce the degree of deformation of the contact tip and to particularly favor physical properties such as rubber elasticity, the rubber material composition has a spring hardness of 70 to 80.
Is particularly preferred.

[0032]

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 blending a raw rubber, a wear improver, and various additives at ratios shown in Tables 1 and 2 and performing the following steps.

[0033]

[Table 1]

[0034]

[Table 2]

First, the various materials used (those described in Tables 1 and 2) will be described.・ Raw material: middle and high nitrile rubber (JSR Corporation, J
SR NBR N230S), ratio of acrylonitrile monomer: 35% ・ Reinforcing filler: carbon black HAF (manufactured by Mitsubishi Chemical Corporation, Diablack H) ・ Reinforcing filler (white filler): hydrated silica (Japan)・ Nip seal AQ manufactured by Silica Industry Co., Ltd. ・ Vulcanizing agent: Highly dispersible sulfur (manufactured by Tsurumi Chemical Industry 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 (Kao Corporation, (Lunac S-35)-Vulcanization accelerator A: Zinc oxide (Sakai Chemical Co., Ltd., France No. 1)-Activator: Organic amine (Yoshitomi Pharmaceutical Co., Ltd., Acting SL)-Plasticizer: Adipic acid-based polyester (PN-350, manufactured by Asahi Denka Co., Ltd.) Abrasion modifier A: carboxyl-modified polyethylene particles (manufactured by Mitsubishi Chemical Corporation, Modic-AP H501) Abrasion modifier B: Carboxyl-modified polypropylene particles (Modic-AP P502, manufactured by Mitsubishi Chemical Corporation) Antioxidant A: 4,4'-bis (α, α-dimethylbenzyl) diphenylamine (Large) Anti-aging agent B: 2-mercaptobenzimidazole (Ouchi Shinko Chemical Co., Ltd., Nocrack MB) Anti-aging agent C: Special wax (Ouchi Shinko Chemical Co., Ltd.) Lubricant: polyethylene wax (320P, manufactured by Mitsui Chemicals, Inc.) Lubricating oil: silicone oil (KF-860, manufactured by Shin-Etsu Silicone Co., Ltd.) Coupling agent: γ-mercaptopropyltrimethoxysilane ( Shin-Etsu Silicone Co., Ltd., KBM803) Next, a rubber material composition is manufactured. Each step to be performed 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 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 10 and Comparative Examples 1 to 3) 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 Tables 3 and 4 show the test results. The numerical values of the wear depth in Tables 3 and 4 are relative values when the wear depth in Example 2 is set to 1.

[0038]

[Table 3]

[0039]

[Table 4]

As can be seen from Tables 3 and 4, Examples 1 to 10 in which acrylonitrile butadiene rubber was used as the raw material rubber and carboxyl-modified polyolefin (carboxyl-modified polyethylene) was used as the wear improving material.
Showed a smaller amount of wear (wear depth) as compared with Comparative Examples 1 and 3 using no carboxyl-modified polyolefin and Comparative Example 2 using a large amount (70 parts by weight) of carboxyl-modified polyolefin.

Here, the effect of the amount of carboxyl-modified polyolefin (carboxyl-modified polyethylene) on the amount of the raw material rubber on the amount of wear will be discussed with reference to the graph of FIG. As can be seen from the graph, the amount of addition of the carboxyl-modified polyolefin, which is
In the case of 60 parts by weight, the wear amount (wear depth) was small and the wear resistance was excellent.

On the other hand, when the amount of the carboxyl-modified polyolefin as the wear improving material was less than 10 parts by weight, the effect of the wear improving material was hardly exhibited and the wear resistance was insufficient. When the amount exceeds 60 parts by weight, the hardness of the rubber material composition increases, and as can be seen from the graph of FIG. 3, the tensile elongation at break decreases and the rubber elasticity is lost.

From these results, it is understood that the amount of the carboxyl-modified polyolefin as the wear improving material is preferably 10 to 60 parts by weight based on 100 parts by weight of the acrylonitrile butadiene rubber as the raw rubber. Next, using the rubber material compositions of Examples 1 to 10 and Comparative Examples 1 to 3, a hub unit seal 100 as shown in FIG. 1 was prepared (the elastic member 107 of the hub unit seal 100 was replaced with the rubber material composition). Object).

Hereinafter, the configuration 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.

Such a hub unit seal 100 was incorporated into 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: 48 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 2 is 1. In addition, the sealing performance was evaluated by the amount of water (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 evaluated as "good", and the case where the water content was 2 to 5% was evaluated as "bad".
, And the case where the water content was 5% or more was indicated as poor by X.

Further, the temperature of the seal lip of the hub unit seal on the driving side was measured by inserting a thermocouple inside the seal lip and rotating it for 24 hours and then at the time of stable rotation (unit: ° C.). .

[0050]

[Table 5]

[0051]

[Table 6]

As can be seen from Tables 5 and 6, Examples 1 to
The hub unit seal composed of the rubber material composition of No. 10 did not use the carboxyl-modified polyolefin, and the hub unit seal composed of the rubber material compositions of Comparative Examples 1 and 3 and the large amount of the carboxyl-modified polyolefin (70)
(Parts by weight) The abrasion loss of the seal lip was smaller than that of the hub unit seal composed of the rubber material composition of Comparative Example 2 used.

The hub unit seals using the rubber material compositions of Examples 1 to 10 had very low moisture 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 10 were also excellent in sealing performance.

Further, a hub unit seal using the rubber material composition of Example 10 containing a polyethylene wax as a lubricant and a rubber material composition of Example 8 containing a modified silicone oil as a lubricant were used. For the hub unit seal, the lubricating properties of the rubber material composition are improved by the action of the lubricant and lubricating oil. Therefore, the temperature of the seal lip is lower than that of the others, and heat generation is suppressed. I understand.

As described above, the rubber material composition of this embodiment uses nitrile rubber as a raw rubber and carboxyl-modified polyolefin as a wear improver.
In addition to the usual crosslinking with a vulcanizing agent, crosslinking proceeds at the carboxyl group 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.

Therefore, the sealing device such as the hub unit seal made of the rubber material composition of the present embodiment provides the wear resistance, bending fatigue resistance, and lubricity of the contact tip (seal lip). Is excellent and generates little heat due to friction. Therefore, the sealing device 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, such as bearings for railway vehicles and hub unit bearings for automobiles,
It is suitable for a rolling device used in a severe environment where a large amount of water and dust are present, and maintains excellent sealing even under such a severe environment, and is excellent in a rolling device. Lifetime can be given.

The following is an example of a rolling device provided with a sealing device made of the rubber material composition of the present embodiment. 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 sleeve 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 grooves 3A of the 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 body 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 which 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 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.

The structure of the linear guide device shown in FIG.
Since it is almost the same as the linear guide device of FIG. 4 described above,
Only different points will be described, and description of the same parts will be omitted. 6, the same or corresponding parts as those in FIG. 4 are denoted by the same reference numerals as those 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 a perspective view in FIG. 6, the lubricant supply member 11 sandwiched therebetween is also a substantially U-shaped member adapted to the outer shape of the end cap 2 </ b> B. , 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 in the same manner as 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 was 10 wt% of ultra-high molecular weight polyethylene (ultra high molecular weight) and 20 wt% of high density polyethylene (relatively low molecular weight).
%, 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 and 15B are larger than the through holes 12a and 12b of the contact seal device 12 and the through holes 10a and 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. 6, 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 is worn. 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.
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 made of the rubber material composition of the present embodiment will be described with reference to the drawings. FIG. 7 is a partially cutaway plan view showing the structure of the ball screw of the present example. FIG. 8 is a front view of the ball screw of FIG. 7, and FIG. 9 is a diagram showing a contact portion between the screw groove 31a of the screw shaft 31 and the contact seal device 42 in the ball screw of FIG. .

The ball screw has a screw shaft 31 having a spiral screw groove 31a having an arc-shaped 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.

Inside the axially opposite ends of the ball screw nut 32, cylindrical lubricant supply members 41, 41 made of a lubricant-containing polymer are fitted and inserted.
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. 6).
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 cross-sectional shape of the screw shaft 31 and having a slightly smaller inner diameter. Then, a seal body 42c for fixing the outer periphery to the ball screw nut 32 (not shown in FIG. 8) and a 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 outer periphery of the cored bar 42b is circular, but its inner periphery is 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. 10 shows that the contact seal device 42 is
It is the elements on larger scale which showed the state which contact | abutted and was deformed.
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 always interference with the outer diameter surface of the screw shaft 31 and the screw groove 31a (in fact,
The gap is kept below 0 by the deformation).

As can be seen from FIG. 10, even if the contact seal device 42 comes into contact with any part of the screw shaft 31 (the outer diameter surface of the screw shaft 31 or the screw groove 31a), 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 of such a contact seal device 42,
The shape and the like are not limited to this example.

When the ball screw nut 32 is moved, the inside is securely sealed by the contact seal device 42 slidingly contacting the screw shaft 31, and the screw shaft 31 and the ball screw nut 32 are moved.
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 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.

[0086]

As described above, since the rubber material composition of the present invention comprises acrylonitrile-butadiene rubber and carboxyl-modified polyolefin, it has excellent abrasion resistance. 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 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 graph showing a correlation between the content of carboxyl-modified polyethylene in a rubber material composition and the wear of a hub unit seal.

FIG. 3 is a graph showing the correlation between the content of carboxyl-modified polyethylene in a rubber material composition and tensile elongation at break.

FIG. 4 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. 5 is a partially enlarged view showing a shape of a lip portion of the contact seal device of the linear guide device of FIG. 4;

FIG. 6 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. 7 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. 8 is a front view of the ball screw of FIG. 7;

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

FIG. 10 is an enlarged view showing a state in which the contact seal 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

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F16H 25/24 F16H 25/24 M (72) Inventor Takahiko Uchiyama 1-5-150 Kugenuma Shinmei 1-chome, Fujisawa-shi, Kanagawa No.N-Seiko Co., Ltd. F-term (reference) 3J016 AA01 AA08 BB03 CA07 3J062 AA51 AB22 AC07 BA23 CD06 CD67 CD68 3J104 AA03 AA23 AA34 AA65 AA69 BA62 CA22 CA23 DA04 4J002 AC07W BB20X FD010 FD170 GJ02 GM05

Claims (1)

[Claims] 1. A rubber material composition comprising acrylonitrile butadiene rubber and a carboxyl-modified polyolefin.