JP2007278515A - sticker - Google Patents

Abstract

In a seal used in a rolling device such as a rolling bearing, an automobile hub unit, a linear guide device, and a ball screw, a seal having a high slidability with respect to a seal contact surface of a lip portion is provided.
The maximum value of loss tangent (tan δ) at a temperature of 20 ° C. to 70 ° C. of a lip portion 13 (here, the entire elastic body 3) made of a rubber molded body of a seal 1 is 0.40 or less. To form.
[Selection] Figure 1

Description

  The present invention relates to a seal used in a rolling device such as a rolling bearing, an automobile hub unit, a hub unit bearing, a linear guide device, and a ball screw. In particular, the present invention relates to a seal suitable for a rolling device used for grease lubrication in a harsh environment where a large amount of water and dust is present.

Conventionally, rolling bearings have been designed to prevent grease existing in the rolling element installation part and dust generated during use from leaking to the outside, and dust floating outside from entering the rolling element installation part. A seal may be attached between the outer ring and the inner ring. An example of a rolling bearing with such a seal is shown in FIG.
The rolling bearing in this figure is a double-seal bearing with seals on both sides, and the seal 1 is formed by integrally vulcanizing and molding a ring-shaped cored bar 2 having a flange on the outer periphery and a synthetic rubber on the outside thereof. It is comprised with the elastic body 3 which becomes. In view of its function, this seal is composed of an annular main portion 11 made of an elastic body other than the flange portion of the core metal and an outer elastic body thereof, and an inner surface of the outer ring 4 made up of the flange portion of the core metal and an elastic body outside the core portion. It is divided into a crimping portion 12 that is locked in the stop groove 41 and a lip portion 13 that is made of an elastic body on the inner peripheral side of the core metal and that is slidably contacted (slidably contacted) with the receiving groove 51 on the outer peripheral surface of the inner ring 5.

The seal 1 is inserted into the retaining groove 41 on the inner peripheral surface of the outer ring while elastically deforming the crimping portion 12 with the lip portion 13 in contact with the receiving groove 51 on the outer peripheral surface of the inner ring. Arranged between the outer ring 4 and the inner ring 5.
Further, as shown in FIG. 3, a seal 10 is also attached to the outer periphery of the automobile hub unit 6, and this seal 10 is also composed of a cored bar 20 and an elastic body 30 made of a molded body of rubber material. . The hub unit 6 is a unit in which a hub 61 into which a shaft is inserted and a flange 62 are integrally formed. The seal 10 has two lip portions 31 and 32 slidably contacted with the hub 61 and one lip portion 33 slidably contacted with the flange 62.
There is also a hub unit bearing in which a hub shaft portion for inserting a shaft is provided between the hub 61 and the flange 62, and an inner ring raceway of a rolling bearing is formed outside the hub shaft portion. A seal is also attached to the hub unit bearing. It has been.

Another example of the seal is shown in FIG. The seal 100 is also composed of a cored bar 200 and an elastic body 300 made of a molded body of rubber material. The seal 100 seals between the inner ring equivalent member 50 having the raceway surface of the rolling element 70 and the outer ring equivalent member 40. The inner ring equivalent member 50 includes a hub portion 50a and a flange portion 50b. The seal 100 includes a radial seal lip portion 301 that is slidably contacted with the outer peripheral surface of the hub portion 50a, and two side seal lip portions 302 and 303 that are slidably contacted with the flange surface of the flange portion 50b.
Typical materials for these seals include steel plates such as SPCC and SECC as the core metal, and synthetic rubbers such as nitrile rubber, acrylic rubber, silicon rubber, and fluorine rubber as the elastic body forming the lip. (See Patent Document 1 below).
JP 2000-161372 A

When the usage environment of such rolling bearings and automotive hub units is in an inferior environment where a large amount of moisture and dust is present, the elasticity of the lip of the seal will decrease over time. Or the lip part is chipped, the slidable contact force (sliding contact force) against the seal contact surface of the lip part (the surface of the mating member that contacts the lip part of the seal) is reduced, and the lip part and the seal contact surface If a minute gap is formed between the two, moisture and dust enter the bearing through the gap. As a result, the grease may deteriorate and the life of the bearing may be reduced.
The present invention has been made by paying attention to such a conventional technique. In a seal used for a rolling device such as a rolling bearing, an automotive hub unit, a hub unit bearing, a linear guide device, and a ball screw, a lip is provided. It is an object of the present invention to provide a seal having high sliding contact with the seal contact surface of the portion.

In order to solve the above problems, the present invention is characterized in that the rubber molded body forming the lip portion has a maximum loss tangent (tan δ) at a temperature of 10 ° C. to 120 ° C. of 0.50 or less. Provide a seal.
The present invention also provides a seal wherein the rubber molded body forming the lip portion has a maximum loss tangent (tan δ) at a temperature of 20 ° C. to 70 ° C. of 0.40 or less.

  When sinusoidal stress and strain are applied to the viscoelastic body, the strain occurs later than the stress. The delay angle of the strain phase with respect to this stress is called the loss angle (δ). The loss tangent (tan δ) is the tangent of the loss angle (δ) and is a measure of the amount of energy dissipated as heat during deformation. The value of the loss tangent (tan δ) of the rubber molded body is measured by performing a dynamic viscoelasticity test in which a load of sinusoidal vibration is applied to the rubber molded body.

  The “maximum value of loss tangent (tan δ) at a temperature of 10 ° C. to 120 ° C.” in the present invention is a loss tangent (tan δ) measured by performing a dynamic viscoelasticity test applying a load of sinusoidal vibration. The maximum value at a test atmosphere temperature of 10 ° C. to 120 ° C. is meant. “Maximum loss tangent (tan δ) at a temperature of 20 ° C. to 70 ° C.” is a test of loss tangent (tan δ) measured by performing a dynamic viscoelasticity test applying a load of sinusoidal vibration. It means the maximum value at an ambient temperature of 20 ° C to 70 ° C.

  The rolling device is usually used in a temperature range of about room temperature to about 120 ° C., and even an automobile hub unit is raised to about 10 ° C. by engine start and is operated at 120 ° C. or less. Therefore, according to the seal of the present invention, by setting the maximum value of the loss tangent (tan δ) at a temperature of 10 ° C. to 120 ° C. of the rubber molded body forming the lip portion to 0.50 or less, In the use temperature range (10 ° C. to 120 ° C.), the sliding contact property with respect to the seal contact surface of the lip portion is maintained.

When the operating temperature range of the rolling device is 20 ° C. to 70 ° C., the maximum value of the loss tangent (tan δ) at 20 ° C. to 70 ° C. of the rubber molded body forming the lip portion is 0.40 or less. By doing so, the sliding property with respect to the seal contact surface of a lip | rip part is hold | maintained in this use temperature range (20 to 70 degreeC).
In the rolling device seal of the present invention, the hardness of the lip portion is preferably in the range of 50 to 90 on the spring hardness A scale described in “JIS K6301”. Thereby, the sealing property by the lip | rip part of a seal becomes favorable.

  When the hardness of the lip portion is less than 50, the lip portion is deformed more than necessary when the seal rotates, and heat generation and torque increase are likely to occur in the lip portion. As a result, the frictional resistance during operation of the rolling device increases, and smooth rotational motion may be difficult. On the other hand, if it exceeds 90, the rubber elasticity is lowered, the sliding contact force with respect to the seal contact surface of the lip portion becomes insufficient, and sufficient sealing performance cannot be obtained. The particularly preferred hardness of the lip portion is in the range of 70 to 80 on the spring hardness A scale.

A rubber molded body having a maximum loss tangent (tan δ) of 0.50 or less at a temperature of 10 ° C. to 120 ° C. and a maximum value of loss tangent (tan δ) at a temperature of 20 ° C. to 70 ° C. of 0.40. The rubber molded body as described below is appropriately mixed with raw material rubber with a compounding agent such as a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, an anti-aging agent, a reinforcing agent, a plasticizer, and a coupling agent as necessary. It is obtained by vulcanizing and molding the blended rubber composition.
If necessary, a reinforcing filler, a processing aid, a wear improver, a lubricating oil, a lubricant and the like can be added to the rubber composition. A rubber molded body having a predetermined hardness can be obtained by adjusting the amount of reinforcing filler, wear improver, etc. added to the rubber composition.

Specific examples of each component of the rubber composition will be described below.
As raw rubber, NR (natural rubber), IR (isoprene rubber), SBR (styrene butadiene rubber), BR (butadiene rubber), CR (chloroprene rubber), NBR (acrylonitrile butadiene rubber), IIR (butyl rubber), EDPM ( Ethylene propylene rubber), urethane rubber, silicone rubber, fluorine rubber, acrylic rubber, and the like can be used.

  Acrylonitrile butadiene rubber (also referred to as “nitrile rubber”) includes low nitrile NBR, medium nitrile NBR, medium high nitrile NBR, high nitrile NBR, and extremely high nitrile NBR, depending on the acrylonitrile content. Of these, medium-high nitrile NBR is particularly preferable in terms of sliding contact, wear resistance, heat resistance, and cold resistance. Further, modified acrylonitrile butadiene rubbers such as acrylonitrile butadiene isoprene rubber copolymerized with isoprene, hydrogenated acrylonitrile butadiene rubber, carboxylated acrylonitrile butadiene rubber, and carboxylated hydrogenated acrylonitrile butadiene rubber may be used alone or in combination of two or more. May be used.

  Vulcanizing agents (crosslinking agents) include (1) various sulfur such as powdered sulfur, sulfur white, precipitated sulfur, highly dispersible sulfur, (2) morpholine disulfide, alkylphenol disulfide, N, N-dithio-bis (hexahydro- Sulfur compounds capable of discharging sulfur such as 2H-azepinone-2) -thiuram polysulfide, (3) Dicumyl peroxide di (t-butylperoxy) diisopropylbenzene, 2,5-dimethylhexane, benzoyl peroxide, etc. And the like. Among these, it is preferable to use highly dispersible sulfur or morpholine disulfide in terms of dispersibility, ease of handling, and heat resistance.

  When sulfur-based vulcanizing agents are used as vulcanization accelerators, guanidine-based, aldevid-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, xanthate-based, etc. Must be used. Of these, when a small amount of highly dispersible sulfur is blended, thiuram-based tetramethylthiuram disulfide, sulfenamide-based N-cyclobenzyl-2-benzothiazyl or sulfenamide, and thiazole-based 2-mercaptobenzothiazole Etc. are preferably used in combination.

  Examples of the vulcanization acceleration aid include metal oxides such as zinc oxide, metal carbonates, metal hydroxides, fatty acids such as stearic acid and derivatives thereof, and amines. When carboxyl-modified nitrile rubber is used as the raw material rubber, a combination of zinc peroxide and stearic acid is preferred because zinc oxide tends to cause early vulcanization. Zinc peroxide is present in the rubber composition as it is at the temperature at which the rubber composition is kneaded and produces zinc oxide at the time of vulcanization molding, so that early vulcanization does not occur at the time of kneading and storage.

Anti-aging agents that prevent oxidative degradation include amine-ketone condensation products, aromatic secondary amines, monophenol derivatives, bis or polyphenol derivatives, bidroquinone derivatives, sulfur-based anti-aging agents, phosphorus-based anti-aging agents, etc. Is given. Among these, 2,2,4-trimethyl-1,2-dibidroquinoline polymer of amine-ketone condensation product system or condensation reaction product of diphenylamine and acetone, aromatic secondary amine system N, N′- Di-β-naphthyl-p-phenylenediamine, 4,4′-bis- (α, α-dimethylbenzyl) diphenylamine, or N-phenyl-N ′-(3-methacryloyloxy-2-bidoxypropyl) −p -Phenylenediamine is preferred.
In order to prevent thermal decomposition and improve heat resistance, it is more preferable to use a secondary anti-aging agent together with the anti-aging agent. Secondary anti-aging agents include sulfur-based 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, and zinc salts thereof.

Furthermore, about 0.5 to 2.0 parts by weight of a wax having a melting point of about 55 to 70 ° C. is added to 100 parts by weight of the raw rubber as a sunlight crack preventing agent that suppresses cracking caused by sunlight or ozone. May be. If the amount is less than 0.5 parts by weight, the effect of preventing cracking due to the action of ozone is hardly obtained. If the amount exceeds 2 parts by weight, unnecessary wax oozes out on the rubber surface, causing a problem in workability. .
Further, when it is necessary to improve the moldability, a plasticizer is appropriately added as a processing aid. When there is no problem in moldability, it is not necessary to add a processing aid. When added, the addition amount is 3 to 20 parts by weight with respect to 100 parts by weight of the raw rubber. If it is added more than necessary, the rubber composition is softened, and there is a possibility that bleed out occurs without being completely mixed.

Specific examples of plasticizers include phthalic acid derivatives such as di- (2-ethylhexyl) phthalate, isophthalic acid derivatives, tetrahydrophthalic acid derivatives, adipic acid derivatives, azelaic acid derivatives, sebacic acid derivatives, dodecanoic acid derivatives, maleic acid derivatives. , Fumaric acid derivatives, trimetic acid derivatives, pyromellitic acid derivatives, citric acid derivatives, itaconic acid derivatives, oleic acid derivatives, ricinoleic acid derivatives, stearic acid derivatives, phosphoric acid derivatives, glutaric acid derivatives, glycol derivatives, glycerin derivatives, paraffin derivatives , Epoxy derivatives, polyester plasticizers, polyether plasticizers, liquid rubbers and the like.
Examples of the coupling agent include silane-based, aluminum-based, and titanate-based coupling agents such as γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. It is done.

Examples of the reinforcing filler include carbon black and white filler. Specifically, as carbon black, ISAF (Intermediate Super Abrasion Furnace black), MAF (Medium Abrasion Furnace black), SRF (Simi-Reinforcing Furnace black), GPF (General Purpose Furnace black), FT (Fine Thermal Furnace black) MT (Medium Thermal Furnace black), HAF (High Abrasion Furnace black), FEF (Fast Extruding Furnace black), and the like. Of these, HAF, FEF, and SRF are preferable in view of reinforcement and followability.
Examples of white fillers include various types of silica, basic magnesium carbonate, activated calcium carbonate, special calcium carbonate, super differential magnesium silicate, clay, talc, diatomaceous earth, and wollastonite. A reinforcing filler obtained by mixing carbon black and a white filler may be used.

When a rubber composition to which a reinforcing filler is added is used, the wear resistance of the lip portion is increased. As a result, the sealing performance by the lip portion of the seal is improved. In the case of carbon black, the addition amount of the reinforcing filler is 20 to 90 parts by weight with respect to 100 parts by weight of the raw rubber. When the amount is less than 20 parts by weight, sufficient reinforcing properties are not exhibited. When the amount exceeds 90 parts by weight, the hardness of the rubber composition increases and the elongation decreases, and the inherent rubber elasticity decreases.
In the case of a white reinforcing agent, the reinforcing filler is added in an amount of 20 to 150 parts by weight with respect to 100 parts by weight of the raw rubber. When the addition amount of the reinforcing filler is less than 20 parts by weight, sufficient reinforcing property is not expressed, and when it exceeds 150 parts by weight, the hardness of the rubber composition is increased and the elongation is decreased, and the inherent rubber elasticity Decreases.

When a mixture of carbon black and white reinforcing agent is used as the reinforcing filler, the amount of carbon black is 10 to 90 parts by weight and the white reinforcing agent is 10 to 110 parts by weight with respect to 100 parts by weight of the raw rubber. The total content is 20 to 200 parts by weight. When the total content of the reinforcing filler is less than 20 parts by weight, sufficient reinforcing property is not expressed. When the total content exceeds 200 parts by weight, the hardness of the rubber composition increases and the elongation decreases, and the inherent rubber Elasticity decreases.
Examples of the wear improver include polyolefin particles and spherical carbon fine particles. Specific examples of the polyolefin particles include polyethylene and polypropylene particles, preferably particles made of carboxyl-modified polyethylene (maleic anhydride-modified polyethylene) and carboxyl-modified polypropylene (maleic anhydride-modified polypropylene).

When polyethylene and polypropylene are carboxyl-modified, they easily adsorb to various rubbers, oxides and the like due to the carboxyl group in the structure. In addition, when carboxyl-modified nitrile rubber is used as the raw material rubber, the carboxyl groups present in the rubber have the same effect, so these synergistic effects can cause mechanical strength, wear resistance, bending fatigue resistance, etc. It is considered that the mechanical strength is further improved.
The addition amount of the polyolefin particles is preferably 10 to 60 parts by weight with respect to 100 parts by weight of the raw rubber from the balance between the wear resistance of the rubber composition and other physical properties. If it is less than 10 parts by weight, the effect of improving the wear resistance is low. On the other hand, when it exceeds 60 parts by weight, the hardness of the rubber composition is increased and the elongation is decreased, so that the rubber elasticity is lowered.

Examples of the lubricating oil include ether oil, silicone oil, poly α-olefin oil, fluorine oil, and fluorine surfactant. Of these, silicone-based oils are more preferable, and modified silicone oils having functional groups are particularly preferable. It is thought that this functional group reacts with the main chain of the rubber to prevent the oil from exuding to the surface of the rubber composition at the same time, and at the same time, gradually exudes permanently. Since the lubricating oil is liquid, it easily oozes onto the surface of the rubber composition, and even a small amount is effective.
The addition amount of the lubricating oil is 2 to 30 parts by weight with respect to 100 parts by weight of the raw rubber. Thereby, the lubricity of a rubber composition improves. If the amount of the lubricating oil added is less than 2 parts by weight, sufficient lubricity will not be exhibited, and if it exceeds 30 parts by weight, the additive will be poorly dispersed during processing of the rubber.

  According to the present invention, the maximum value of the loss tangent (tan δ) at a temperature of 10 ° C. to 120 ° C. is 0.50 or less (or the loss tangent (tan δ at a temperature of 20 ° C. to 70 ° C.). As a seal used for rolling devices such as rolling bearings, automotive hub units, hub unit bearings, linear guide devices, ball screws, etc. A seal having a high sliding contact with the seal contact surface of the lip portion is obtained.

In other words, since this seal is excellent in sliding contact with the seal contact surface of the lip portion, high sealing performance is maintained even in a harsh environment where a large amount of water and dust exist, and grease leakage occurs. Intrusion of water and dust is prevented.
Therefore, the life of the rolling device can be extended by attaching the seal of the present invention to the rolling device used in a harsh environment where a large amount of water and dust are present.

Hereinafter, embodiments of the present invention will be described.
The following materials were prepared as materials for the rubber composition.
☆ Raw material A: Medium-high nitrile NBR (“JSR NBR N230S” manufactured by JSR Corporation), ratio of acrylonitrile monomer: 35%
☆ Raw material B: Carboxylicated medium-high nitrile NBR (“Nipol DN631” manufactured by Nippon Zeon Co., Ltd.), ratio of acrylonitrile monomer: 33.5%
☆ Raw rubber C: High nitrile NBR (“JSR NBR N222S” manufactured by JSR Corporation), ratio of acrylonitrile monomer: 43%
☆ Raw material D: Medium nitrile NBR (“JSR NBR N241S” manufactured by JSR Corporation), ratio of acrylonitrile monomer: 29%

☆ Rubber E: Medium nitrile NBR (“JSR NBR N240S” manufactured by JSR Corporation), ratio of acrylonitrile monomer: 26%
☆ Raw material F: Medium nitrile NBR (“Nipol DN2850” manufactured by Zeon Corporation), ratio of acrylonitrile monomer: 28%
☆ Raw rubber G: Medium nitrile NBR (“Nipol DN3350” manufactured by Nippon Zeon Co., Ltd.), ratio of acrylonitrile monomer: 33%
☆ Raw material H: High nitrile NBR (“JSR NBR N235S” manufactured by JSR Corporation), ratio of acrylonitrile monomer: 36%
☆ Raw rubber I: High nitrile NBR (“JSR NBR N220S” manufactured by JSR Corporation), ratio of acrylonitrile monomer: 41%

☆ Carbon black A: HAF ("Dia Black H" manufactured by Mitsubishi Chemical Corporation)
☆ Carbon Black B: SRF ("Seast S" manufactured by Tokai Carbon Co., Ltd.)
☆ Silica: Hydrous silica (“Nip Seal AQ” manufactured by Nippon Silica Industry Co., Ltd.)
☆ Silane modified clay: “ST-301” manufactured by Shiraishi Calcium Co., Ltd.
☆ Baking clay: “SATINTONE No. 5” manufactured by Tsuchiya Kaolin Co., Ltd.
☆ Talc: “MP10-52” manufactured by Pfizer
☆ Wollastonite: “NYAD10” manufactured by NYCO
☆ Vulcanizing agent: Highly dispersible sulfur ("Sulfalx PMC" manufactured by Tsurumi Chemical Co., Ltd.)

☆ Vulcanization accelerator A: Tetramethylthiuram disulfide ("Axel TMT" manufactured by Kawaguchi Chemical Co., Ltd.)
☆ Vulcanization accelerator B: Tetraethylthiuram disulfide ("Noxeller TET" manufactured by Ouchi Shinsei Chemical Co., Ltd.)
☆ Vulcanization accelerator C: N-cyclohexyl-2-benzothiazyl sulfenamide ("Accel CZ-R" manufactured by Kawaro Chemical Industry Co., Ltd.)

☆ Vulcanization Accelerator A (also serves as a lubricant): Stearic acid ("Lunac S-35" manufactured by Kao Corporation)
☆ Vulcanization accelerator B: Zinc oxide (“French No. 1” manufactured by Sakai Chemical Co., Ltd.)
☆ Vulcanization accelerator C: Zinc oxide (“ZeonetZP” manufactured by Nippon Zeon Co., Ltd.), 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.)
☆ Abrasion improver: Carboxyl-modified polyethylene particles ("Modic-APH501" manufactured by Mitsubishi Chemical Corporation)

☆ Anti-aging agent A: 4,4-bis- (α, α-dimethylbenzyl) diphenylamine (“NOCRACK CD” manufactured by Ouchi Shinsei Chemical Co., Ltd.)
☆ Anti-aging agent B: 2-mercaptobenzimidazole (“NOCRACK MB” manufactured by Ouchi Shinsei Chemical Co., Ltd.)
☆ Anti-aging agent C: Special wax ("Sannok" manufactured by Ouchi Shinsei Chemical Co., Ltd.)
☆ Lubricant: Amino-modified silicone oil (“KF-860” manufactured by Shin-Etsu Silicone Co., Ltd.)
☆ Coupling agent: γ-mercaptopropyltrimethoxysilane (“KBM803” manufactured by Shin-Etsu Silicone Co., Ltd.)

[First Embodiment]
Rubber compositions Nos. 1-1 to 1-5 having the compositions shown in Table 1 below were prepared.

Using these rubber compositions, test pieces for a hardness test were produced by the following method.
First, each material except a vulcanizing agent and a vulcanization accelerator was put into a Banbury mixer and kneaded at a mixer temperature of 80 ° C. (first kneading step). Next, the kneaded material was taken out from the Banbury mixer and put into a two-roll rubber kneading roll machine. Next, while controlling the roll temperature to 50 ° C., the vulcanizing agent and the vulcanization accelerator were introduced into this roll machine, and the turning operation was performed until it became uniform (second kneading step), and then into a sheet shape Formed.

Next, a 2 mm thick sheet vulcanization mold was mounted on a hot press machine heated to 170 ° C., and the sheet obtained in the second kneading step was placed in the mold. And it heated and pressurized for 15 minutes, and obtained the vulcanized rubber sheet of length 150mm, width 150mm, and thickness 2mm. The rubber sheet was punched into the shape of a JIS No. 3 test piece to obtain a test piece for hardness test.
Three test pieces were used in an overlapping manner, and the hardness was measured with a spring hardness A scale based on “JIS K6301”.
Further, a test piece for a dynamic viscoelasticity test was cut out from the hub unit seal 10 of FIG. This test piece was cut out in accordance with an effective measurement dimension: 10 mm × 2.7 mm × thickness 0.5 mm.

Using this test piece, based on “JIS K 7244-4”, a dynamic viscoelasticity test for applying a load of sinusoidal vibration was performed at an ambient temperature of 10 ° C. to 120 ° C., and at each temperature in the above temperature range. Loss tangent (tan δ) was determined. As a tester, a viscoelasticity measuring device “RSA-II” manufactured by Rheometric Scientific F.E. was used, measurement mode: tensile mode, measurement frequency: 10 Hz, initial strain: 2.0%, dynamic The test was conducted under the condition of mechanical strain: 0.1%.
The test results are shown in Table 2 below. Table 2 shows the maximum value of tan δ at the atmospheric temperature of 10 ° C to 120 ° C.

  As can be seen from the results in Table 2, the rubber molded body obtained by vulcanization molding of the rubber compositions of No. 1-1 to 1-5 has a hardness of 70 or more according to the spring hardness A scale. Yes. In addition, a rubber molded body (molded body of No. 1-1 to 1-4) obtained by vulcanization molding of the rubber composition of No. 1-1 to 1-4 was obtained at 10 ° C to 120 ° C. Although the maximum value of loss tangent (tan δ) is 0.50 or less, a rubber molded body obtained by vulcanization molding of No. 1-5 rubber composition (molded body of No. 1-5) ), The maximum value exceeds 0.50.

Next, the seal 1 of the rolling bearing shown in FIG. 1 was produced by the following method. Vulcanization molding composed of each rubber composition by placing the core metal 2 made of SPCC and the rubber composition of No. 1-1 to 1-5 into a vulcanization mold for forming a seal, followed by heat and pressure molding. The body was molded integrally as an elastic body 3 on the outside of the core metal 2. The lip portion 13 of the elastic body 3 has a shape shown in FIG.
Each of the obtained seals (seal in which the elastic body 3 is each molded body of No. 1-1 to 1-5) 1 was replaced with 6203 (nominal number) single-row deep groove ball bearing (Fig. 1) manufactured by NSK Ltd. The rolling bearing was assembled between the inner ring 5 and the outer ring 4. This bearing was run on a bearing rotation tester manufactured by Nippon Seiko Co., Ltd., and after it was rotated under the conditions of enclosed grease: ether grease, ambient temperature: 80 ° C., rotation speed: 10,000 rpm, rotation time: 1000 hours, The lip portion was examined for cuts.
The test results are shown in Table 3 below. The case where grease leaks and the lip portion was broken was indicated as “X”, and the case where it did not occur was indicated as “◯”.

  As can be seen from the results in Table 3, in the bearing incorporating the seals No. 1-1 to 1-4, in which the elastic body 3 is formed of No. 1-1 to 1-4, the grease is also measured by the rotation test. In the bearing in which the elastic body 3 incorporated the No. 1-5 seal made of the No. 1-5 molded body, while the leakage and seal breakage did not occur, the grease leakage and seal were determined by the rotation test. The loss occurred.

  Next, the seal 10 of the hub unit 6 shown in FIG. 3 was produced by the following method. Vulcanization molding consisting of each rubber composition by placing the core metal 20 made of SPCC and the rubber composition of No. 1-1 to 1-5 in a vulcanization mold for forming a seal, followed by heat and pressure molding. The body was formed integrally with the core metal 20 as the elastic body 30. The lip portions 31 to 33 of the elastic body 30 have the shape shown in FIG.

  Each of the obtained seals (seal made of molded bodies of elastic bodies 30 of Nos. 1-1 to 1-5) 10 was attached to a hub unit 6 shown in FIG. In the state, it attached to the hub unit rotation testing machine made from NSK Ltd. Then, the shaft eccentricity was set to each value of 0 to 0.7 mm TIR (Total Indicator Reading), and the hub unit was rotated under the following conditions while applying muddy water toward the hub unit 6 and the seal 10. Muddy water supply condition: Repeated to stop applying muddy water for 20 seconds after applying 2 liters of muddy water for 10 seconds per minute. Grease enclosed between hub unit 6 and seal 10: Mineral oil grease, atmosphere Temperature: room temperature, rotation speed: 1000 rpm, rotation time: 50 hours.

After this rotation test, the amount of water contained in the sealed grease of each specimen is measured, and the slidability of the lip portions 31 to 33 of the seal 10 with respect to the hub unit 6 is determined based on the content of this amount of water (mass) with respect to the grease mass. Evaluated.
If the said content rate is 1.0% or less, the sliding contact property with respect to the hub unit 6 of the lip | rip parts 31-33 of the seal | sticker 10 will be favorable "(circle)", and in the case of 2.0-5.0%, it is a somewhat bad " “△”, and when it was 5.0% or more, it was judged as “bad”. The test results are shown in Table 4 below.
Further, a thermocouple is inserted into the lip portion (main lip) 32 of the seal 10 and rotated with the shaft eccentricity set to 0, and the lip portion (main lip) 32 during stable rotation (when rotated for 30 hours or more). The temperature of was measured. The results are shown in Table 5 below.

  As can be seen from the results in Table 4, when the shaft eccentricity is 0, the lip portion in the rotation test is slidable with respect to the hub unit even when any of seals Nos. 1-1 to 1-5 is incorporated. Was good. However, when a No. 1-5 seal (a seal having a maximum loss tangent (tan δ) at 10 ° C to 120 ° C of 0.54) is incorporated, the shaft eccentricity is 0.05. When the thickness was ˜0.15 mm TIR, the slidability of the lip portion with respect to the hub unit in the rotation test was slightly poor, and when it was 0.20 mm TIR or more, it was poor.

  In contrast, No. 1-1, 1-3, 1-4 seals (seal whose maximum loss tangent (tan δ) at 10 ° C. to 120 ° C. of the elastic body is 0.32 or less). When incorporated, even if the shaft eccentricity was 0.70 mm TIR, the slidability of the lip portion to the hub unit in the rotation test was good. Further, the hub of the lip portion in the rotation test in which the No. 1-2 seal (a seal having a maximum loss tangent (tan δ) at 10 ° C. to 120 ° C. of 0.50) is incorporated. The sliding contact with the unit was good when the shaft eccentricity was 0 to 0.60 mm TIR, and slightly poor when the shaft eccentricity was 0.65 to 0.70 mm TIR.

  As can be seen from the results in Table 5, the temperature of the main lip is No. 1-5 seal (the maximum value of the loss tangent (tan δ) of the elastic body at 10 ° C. to 120 ° C. is 0.54). 89 ° C. when the seal is incorporated, and the maximum loss tangent (tan δ) of No. 1-1 to 1-4 seal (elastic body at 10 ° C. to 120 ° C. is 0.26 to 0. 0. The temperature of the main lip when the seal (50) was incorporated was higher than 45 to 75 ° C.

  The reason why the temperature of the main lip of No. 1-5 seal rose to 89 ° C is that the main lip has poor sliding contact with the hub unit, and the force with which the main lip pushes the hub (shaft) is not good in the circumferential direction of the shaft. It is presumed that heat was generated uniformly. Further, since the elastic body of the seal No. 1-4 was made of a rubber molded body containing silicone oil, the main lip had a particularly low temperature of 45 ° C. because the main lip had high lubricity.

[Second Embodiment]
The rubber compositions Nos. 2-1 to 2-11 having the compositions shown in Table 6 below were prepared.

Using these rubber compositions, test pieces for a hardness test were produced by the following method.
First, each material except a vulcanizing agent and a vulcanization accelerator was put into a Banbury mixer and kneaded at a mixer temperature of 80 ° C. (first kneading step). Next, the kneaded material was taken out from the Banbury mixer and put into a two-roll rubber kneading roll machine. Next, while controlling the roll temperature to 50 ° C., the vulcanizing agent and the vulcanization accelerator were introduced into this roll machine, and the turning operation was performed until it became uniform (second kneading step), and then into a sheet shape Formed.

  Next, a 2 mm thick sheet vulcanization mold was mounted on a hot press machine heated to 170 ° C., and the sheet obtained in the second kneading step was placed in the mold. And it heated and pressurized for 15 minutes, and obtained the vulcanized rubber sheet of length 150mm, width 150mm, and thickness 2mm. The rubber sheet was punched into the shape of a JIS No. 3 test piece to obtain a test piece for hardness test.

Three test pieces were used in an overlapping manner, and the hardness was measured with a spring hardness A scale based on “JIS K6301”.
Further, test pieces for a dynamic viscoelasticity test were cut out from the rolling bearing seal 1 shown in FIG. 1 and the hub unit seal 10 shown in FIG. The test piece for the seal 1 corresponds to an effective measurement dimension: 4 mm × 20 mm × 0.8 mm thickness, and the test piece for the seal 10 has an effective measurement dimension: 10 mm × 2.7 mm × 0.5 mm thickness. Cut out correspondingly.

Using this test piece, based on “JIS K 7244-4”, a dynamic viscoelasticity test is performed by applying a load of sinusoidal vibration at an ambient temperature of 20 ° C. to 70 ° C., and loss tangent at each temperature in the above temperature range. (Tan δ) was determined. As a tester, a viscoelasticity measuring device “RSA-III” manufactured by Rheometric Scientific F.E. was used. Measurement mode: tensile mode, measurement frequency: 10 Hz, initial strain: 2.0%, dynamic The test was conducted under the condition of mechanical strain: 0.1%.
The test results are shown in Table 7 below. Table 7 shows the maximum value of tan δ at an ambient temperature of 20 ° C to 70 ° C.

  As can be seen from the results in Table 7, the rubber molded body obtained by vulcanization molding of the rubber compositions of Nos. 2-1 to 2-11 had a hardness by a spring hardness A scale of 70 or more. Yes. Also, rubber molded bodies obtained by vulcanization molding of rubber compositions No. 2-1 to 2-5, 2-7 to 2-10 (No. 2-1 to 2-5, 2-7 to 2-10), the maximum loss tangent (tan δ) at 20 ° C. to 70 ° C. is 0.40 or less for both the bearing seal and the hub unit seal. A rubber molded body obtained by vulcanization molding of the rubber composition of 2-6 and 2-11 (molded body of No. 2-6 and 2-11) is either a bearing seal or a hub unit seal. The maximum value exceeds 0.40.

Next, the seal 1 of the rolling bearing shown in FIG. 1 was produced by the following method. Vulcanization molding composed of each rubber composition by placing the core metal 2 made of SPCC and the rubber composition of No. 2-1 to 2-11 in a vulcanization mold for forming a seal and heat-press molding. The body was molded integrally as an elastic body 3 on the outside of the core metal 2. The lip portion 13 of the elastic body 3 has a shape shown in FIG.
Each of the obtained seals (seal in which the elastic body 3 is formed of each molded body of No. 2-1 to 2-11) 1 was replaced with 6203 (nominal number) single row deep groove ball bearing (Fig. 1) manufactured by Nippon Seiko Co., Ltd. The rolling bearing was assembled between the inner ring 5 and the outer ring 4. This bearing was run on a bearing rotation tester manufactured by Nippon Seiko Co., Ltd., and after it was rotated under the conditions of enclosed grease: ether grease, ambient temperature: 80 ° C., rotation speed: 10,000 rpm, rotation time: 1000 hours, The lip portion was examined for cuts.
The test results are shown in Table 8 below. The case where grease leaks and the lip portion was broken was indicated as “X”, and the case where it did not occur was indicated as “◯”.

  As can be seen from the results in Table 8, the elastic bodies 3 are Nos. 2-1 to 2-5, 2-7 to 2 consisting of molded bodies of Nos. 2-1 to 2-5, 2-7 to 2-10. In the bearing incorporating the seal of -10, grease leakage and seal breakage did not occur even in the rotation test, whereas the elastic body 3 was No. 2-6 and 2-11 formed body. In bearings incorporating the seals 2-6 and 2-11, grease leakage and seal breakage were caused by the rotation test.

  Next, the seal 10 of the hub unit 6 shown in FIG. 3 was produced by the following method. Vulcanization molding composed of each rubber composition by placing the core material 20 made of SPCC and the rubber composition of No. 2-1 to 2-11 in a vulcanization mold for forming a seal and then heat-pressing the rubber composition. The body was formed integrally with the core metal 20 as the elastic body 30. The lip portions 31 to 33 of the elastic body 30 have the shape shown in FIG.

Each of the obtained seals (seal made of molded bodies of elastic bodies 30 No. 2-1 to 2-11) 10 was attached to a hub unit 6 in which the inner diameter of the hub 61 is 60 mm as shown in FIG. In the state, it attached to the hub unit rotation testing machine made from NSK Ltd. Then, the shaft eccentricity was set to each value of 0 to 0.7 mm TIR (Total Indicator Reading), and the hub unit was rotated under the following conditions while applying muddy water toward the hub unit 6 and the seal 10. Muddy water supply condition: Repeated to stop applying muddy water for 20 seconds after applying 2 liters of muddy water for 10 seconds per minute. Grease enclosed between hub unit 6 and seal 10: Mineral oil grease, atmosphere Temperature: room temperature, rotation speed: 1000 rpm, rotation time: 50 hours.
After this rotation test, the amount of water contained in the sealed grease of each specimen is measured, and the slidability of the lip portions 31 to 33 of the seal 10 with respect to the hub unit 6 is determined based on the content of this amount of water (mass) with respect to the grease mass. Evaluated.

If the said content rate is 1.0% or less, the sliding contact property with respect to the hub unit 6 of the lip | rip parts 31-33 of the seal | sticker 10 will be favorable "(circle)", and in the case of 2.0-5.0%, it is a somewhat bad " “△”, and when it was 5.0% or more, it was judged as “bad”. The test results are shown in Table 9 below.
Further, a thermocouple is inserted into the lip portion (main lip) 32 of the seal 10 and rotated with the shaft eccentricity set to 0, and the lip portion (main lip) 32 during stable rotation (when rotated for 30 hours or more). The temperature of was measured. The results are shown in Table 10 below.

As can be seen from the results in Table 9, when the shaft eccentricity is 0, the lip portion is slidably contacted with the hub unit in the rotation test even if any of seals Nos. 2-1 to 2-11 is incorporated. Was good. However, when the seal No. 2-6 (the seal having the maximum loss tangent (tan δ) at 20 ° C. to 70 ° C. of 0.44) is incorporated, the shaft eccentricity is 0.05. When the thickness was ˜0.15 mm TIR, the slidability of the lip portion with respect to the hub unit in the rotation test was slightly poor, and when it was 0.20 mm TIR or more, it was poor.
In addition, when a No. 2-11 seal (a seal having a maximum loss tangent (tan δ) at 20 ° C. to 70 ° C. of 0.42) is incorporated, the shaft eccentricity is 0.15. When the thickness was ˜0.25 mm TIR, the slidability of the lip portion with respect to the hub unit in the rotation test was slightly poor, and when it was 0.30 mm TIR or more, it was poor.

  On the other hand, the seals of No. 2-1, 2-2, 2-4, 2-5, 2-7 to 2-10 (loss tangent (tan δ) of elastic body at 20 ° C. to 70 ° C.) When a seal having a maximum value of 0.11 to 0.26 was incorporated, the slidability of the lip portion to the hub unit in the rotation test was good even if the shaft eccentricity was 0.70 mm TIR. Further, the hub of the lip portion in the rotation test in which the No. 2-3 seal (the seal having the maximum loss tangent (tan δ) at 20 ° C. to 70 ° C. of 0.40) is incorporated. The sliding contact with the unit was good when the shaft eccentricity was 0 to 0.55 mm TIR, and slightly poor when the shaft eccentricity was 0.60 to 0.70 mm TIR.

  Further, as can be seen from the results of Table 10, the temperature of the main lip is No. 2-6, 2-11 seal (the maximum loss tangent (tan δ) of the elastic body at 20 ° C. to 70 ° C. is 0). No. 2-1 to 2-5 and 2-6 to 2-10 seals (20 ° C. to 70 ° C. of the elastic body). The temperature of the main lip was higher than 45 to 75 ° C. when a seal having a maximum loss tangent (tan δ) at 0.1 ° C. of 0.11 to 0.40 was incorporated.

The reason for the high temperature of the main lip is presumably because the main lip has poor sliding contact with the hub unit, and the force with which the main lip presses the hub (shaft) becomes uneven in the circumferential direction of the shaft and heat is generated. . Further, since the elastic body of No. 2-5 seal is made of a rubber molded body containing silicone oil, the main lip has a particularly low temperature of 45 ° C. because the main lip has high lubricity.
Furthermore, in this embodiment, as described above, various nitrile rubbers (NBR) having different acrylonitrile contents are used as the raw rubber. Therefore, the relationship between the acrylonitrile content in the raw material NBR of each sample and the tan δ maximum value (maximum value at an ambient temperature of 20 ° C. to 70 ° C.) measured with a test piece cut out from the hub unit seal is shown in FIG. Is shown in the graph.

Here, although the acrylonitrile content rate in the raw material NBR of No. 2-2, 2-3, 2-5 is the same value (35%), No. 2-3 does not contain carbon black but silica. It is greatly different from Nos. 2-1, 2-6 to 2-11 in that it contains a coupling agent. In addition, No. 2-5 is greatly different from other samples in that it contains lubricating oil. Therefore, No. 2-2 is used as a sample of “acrylonitrile content = 35%” to be compared with other samples.
Therefore, it can be seen from the graph of FIG. 4 that the tan δ maximum value (maximum value at an ambient temperature of 20 ° C. to 70 ° C.) increases as the acrylonitrile content in the raw material NBR increases.

In addition, the seals of sample Nos. 2-6 and 2-11 having a tan δ maximum value larger than 0.40 have poor sealing performance (grease leakage or seal breakage may occur in each of the above tests). As a result, when the nitrile rubber is used as the raw rubber, the smaller the acrylonitrile content, the higher the sealing performance. Conceivable.
The acrylonitrile content when nitrile rubber is used as the raw rubber is preferably 26% or more and 36% or less. The nitrile rubber molded product with the content of less than 26% has insufficient adhesion to the core metal, and when the content exceeds 36%, the tan δ maximum value of the nitrile rubber molded product increases rapidly. Thus, the slidability with respect to the seal contact surface of the lip portion becomes insufficient.

[Third Embodiment]
The rubber compositions Nos. 3-1 to 3-12 having the compositions shown in Table 11 below were prepared.

Using these rubber compositions, a test piece for hardness test (JIS No. 3 test piece) was produced by the same method as in the second embodiment. Three test pieces were used in an overlapping manner, and the hardness was measured with a spring hardness A scale based on “JIS K6301”.
Further, test pieces for a dynamic viscoelasticity test were cut out from the rolling bearing seal 1 shown in FIG. 1 and the hub unit seal 10 shown in FIG. The test piece for the seal 1 corresponds to an effective measurement dimension: 4 mm × 20 mm × 0.8 mm thickness, and the test piece for the seal 10 has an effective measurement dimension: 10 mm × 2.7 mm × 0.5 mm thickness. Cut out correspondingly.

Using this test piece, based on “JIS K 7244-4”, a dynamic viscoelasticity test is performed by applying a load of sinusoidal vibration at an ambient temperature of 20 ° C. to 70 ° C., and loss tangent at each temperature in the above temperature range. (Tan δ) was determined. As a tester, a viscoelasticity measuring device “RSA-III” manufactured by Rheometric Scientific F.E. was used. Measurement mode: tensile mode, measurement frequency: 10 Hz, initial strain: 2.0%, dynamic The test was conducted under the condition of mechanical strain: 0.1%.
The test results are shown in Table 12 below. Table 12 shows the maximum value of tan δ at an ambient temperature of 20 ° C to 70 ° C.

  As can be seen from the results in Table 12, the rubber molded bodies obtained by vulcanization molding of the rubber compositions of Nos. 3-1 to 3-12 all have a hardness of 70 or more according to the spring hardness A scale. In both the bearing seal and the hub unit seal, the maximum value of the loss tangent (tan δ) at 20 ° C. to 70 ° C. is 0.40 or less.

Next, the seal 1 of the rolling bearing shown in FIG. 1 was produced by the following method. Vulcanization molding composed of each rubber composition by placing the core metal 2 made of SPCC and the rubber composition of Nos. 3-1 to 3-12 in a vulcanization mold for forming a seal, followed by heat and pressure molding. The body was molded integrally as an elastic body 3 on the outside of the core metal 2. The lip portion 13 of the elastic body 3 has a shape shown in FIG.
Each of the obtained seals (seal made of each molded body of elastic bodies 3 No. 3-1 to 3-12) 1 was replaced with 6203 (nominal number) single row deep groove ball bearing (FIG. 1) manufactured by NSK Ltd. The rolling bearing was assembled between the inner ring 5 and the outer ring 4. This bearing was run on a bearing rotation tester manufactured by Nippon Seiko Co., Ltd., and after it was rotated under the conditions of enclosed grease: ether grease, ambient temperature: 80 ° C., rotation speed: 10,000 rpm, rotation time: 1000 hours, The lip portion was examined for cuts.
The test results are shown in Table 13 below. The case where grease leaks and the lip portion was broken was indicated as “X”, and the case where it did not occur was indicated as “◯”.

  As can be seen from the results in Table 13, the elastic body 3 is a bearing incorporating all seals made of molded bodies of Nos. 3-1 to 3-12. Grease leakage and seal breakage are also caused by the rotation test. Did not occur.

  Next, the seal 10 of the hub unit 6 shown in FIG. 3 was produced by the following method. Vulcanization molding consisting of each rubber composition by placing the core metal 20 made of SPCC and the rubber composition of Nos. 3-1 to 3-12 in a vulcanization mold for forming a seal, followed by heat and pressure molding. The body was formed integrally with the core metal 20 as the elastic body 30. The lip portions 31 to 33 of the elastic body 30 have the shape shown in FIG.

  Each of the obtained seals (seal made of molded bodies having elastic bodies 30 of Nos. 3-1 to 3-12) 10 was attached to a hub unit 6 having an inner diameter of a hub 61 shown in FIG. In the state, it attached to the hub unit rotation testing machine made from NSK Ltd. Then, the shaft eccentricity was set to each value of 0 to 0.7 mm TIR (Total Indicator Reading), and the hub unit was rotated under the following conditions while applying muddy water toward the hub unit 6 and the seal 10. Muddy water supply condition: Repeated to stop applying muddy water for 20 seconds after applying 2 liters of muddy water for 10 seconds per minute. Grease enclosed between hub unit 6 and seal 10: Mineral oil grease, atmosphere Temperature: room temperature, rotation speed: 1000 rpm, rotation time: 50 hours.

After this rotation test, the amount of water contained in the sealed grease of each specimen is measured, and the slidability of the lip portions 31 to 33 of the seal 10 with respect to the hub unit 6 is determined based on the content of this amount of water (mass) with respect to the grease mass. Evaluated.
If the said content rate is 1.0% or less, the sliding contact property with respect to the hub unit 6 of the lip | rip parts 31-33 of the seal | sticker 10 will be favorable "(circle)", and in the case of 2.0-5.0%, it is a somewhat bad " “△”, and when it was 5.0% or more, it was judged as “bad”. The test results are shown in Table 14 below.
Further, a thermocouple is inserted into the lip portion (main lip) 32 of the seal 10 and rotated with the shaft eccentricity set to 0, and the lip portion (main lip) 32 during stable rotation (when rotated for 30 hours or more). The temperature of was measured. The results are shown in Table 15 below.

  As can be seen from the results in Table 14, when the shaft eccentricity is 0.55 mm TIR or less, any of the seals of Nos. 3-1 to 3-12 is incorporated, and the lip portion in the rotation test with respect to the hub unit The sliding contact was good. Further, the seals of Nos. 3-1, 3-2 and Nos. 3-5 to 3-12 (the maximum value of the loss tangent (tan δ) of the elastic body at 20 ° C. to 70 ° C. is 0.08 or more and 0.0. When a seal of 31 or less was incorporated, the slidability of the lip portion to the hub unit in the rotation test was good even if the shaft eccentricity was 0.70 mm TIR.

  On the other hand, when a No. 3-2 seal (a seal having a maximum loss tangent (tan δ) at 20 ° C. to 70 ° C. of 0.36) is incorporated, the shaft eccentricity is When the thickness was 0.70 mm TIR, the slidability of the lip portion with respect to the hub unit in the rotation test was slightly poor. In addition, when a No. 3-3 seal (a seal having a maximum loss tangent (tan δ) at 20 ° C. to 70 ° C. of 0.40) is incorporated, the shaft eccentricity is 0.60 mm TIR. When it became above, the sliding property with respect to the hub unit of the lip | rip part in the said rotation test became a little bad.

From this result, the preferred range of the maximum value of the loss tangent (tan δ) at 20 ° C. to 70 ° C. of the rubber molded body (elastic body) forming the lip portion can be 0.08 or more and 0.31 or less. .
Further, as can be seen from the results in Table 15, the temperature of the main lip was 73 ° C. or less for all the seals, which was a good value.

[Muddy water durability test]
A muddy water durability test of the sealed hub unit shown in FIG. 3 was performed using a muddy water durability test apparatus manufactured by NSK Ltd. shown in FIG.
This device includes a rotating shaft 110, a housing 120, a shaft-side annular member 130 fixed to the rotating shaft 110 with a bolt, a housing-side annular member 140 fixed to the housing 120, a water leakage sensor 150, and a rotation not shown. It consists of a drive device. Further, muddy water 115 is stored in a space 121 on the front end side of the rotating shaft in the housing 120. When the hub unit 160 with seal is attached to this apparatus, the hub 61 is inserted between the rotary shaft 110 and the housing side annular member 140 with the hub 61 attached to the shaft side annular member 130, and the shaft side annular member 130 is inserted. Is fixed to the rotating shaft 110 with bolts.

In this test, the elastic bodies 30 constituting the seal 10 are No. 1-1 to 1-4 molded bodies produced in the first embodiment, No. 2-1 and No. 2 produced in the second embodiment. 2-4, Nos. 2-7 to 2-10, and No. 3-1 to 3-12 formed in the third embodiment. These seals 10 are “good (◯)” or “slightly poor (Δ)” when the shaft eccentricity is 0.70 mm TIR in the above-described sliding contact evaluation test.
Each of these seals 10 was incorporated into the test apparatus shown in FIG. 6, and the hub unit was rotated under the following conditions with an axial eccentricity of 0.50 mm TIR, and the time until water leaked from the seal 10 (muddy water durability time) was examined. The rotation conditions were grease enclosed between the hub unit 6 and the seal 10: mineral oil grease, ambient temperature: room temperature, and rotation speed: 1000 rpm.

  Next, a relative value with the value of No. 1-2 set to “1” was calculated from the muddy water durability time obtained with each seal. The results are shown in Table 16 below together with the maximum value of tan δ at the atmospheric temperature 20 ° C. to 70 ° C. of the elastic body 30 forming each seal.

FIG. 7 is a graph showing the relationship between the maximum value of tan δ at the atmospheric temperature of 20 ° C. to 70 ° C. and the muddy water durability time (relative value) obtained from this result. Show.
From this graph, it can be seen that the muddy water durability time increases as the maximum value of tan δ decreases. In particular, when the maximum value of the tan δ is 0.19 or less, it can be seen that the muddy water durability time is abruptly increased and is saturated near 0.10. That is, a rubber molded body having a maximum tan δ of 0.19 or less (or 0.08 or more and 0.19 or less, or 0.10 or more and 0.19 or less) at an ambient temperature of 20 ° C. to 70 ° C. is used. As a result, the muddy water durability performance (sealing performance) of the seal can be particularly increased. Further, from this graph, the value of the “maximum value of the tan δ” particularly preferable in terms of the muddy water durability performance (sealing performance) of the seal is 0.15 or less (or 0.08 or more and 0.15 or less, or 0. 10 to 0.15).

Of the results shown in Table 16, the results for the sample using the raw rubber G are shown in a graph in FIG. This graph also shows the relationship between the maximum value of tan δ at the atmospheric temperature 20 ° C. to 70 ° C. of the elastic body 30 forming each seal and the muddy water durability time (relative value).
In this graph, “◯” is a plot of samples (No. 3-6 to 3-12) using two types of carbon black and clay as reinforcing fillers, and “Δ” is reinforcing packing. It is a plot of the sample (No. 2-9, No. 3-1 to 3-5) which uses only any one of carbon black, clay, talc, and wollastonite as an agent.

  As can be seen from this graph, the use of a mixture of carbon black and white filler (clay, talc, wollastonite, etc.) as a reinforcing filler is more elastic than using either one alone. The maximum value of tan δ at the atmospheric temperature of 20 ° C. to 70 ° C. of the body 30 can be increased, and as a result, the muddy water durability performance (sealing performance) of the seal can be particularly increased.

In addition, the content of the reinforcing filler is 10 to 90 parts by weight of carbon black and 10 to 110 parts by weight of the white reinforcing agent with respect to 100 parts by weight of the raw rubber, as described above, and the total content is The amount of carbon black is 20 to 100 parts by weight and the white reinforcing agent is 20 to 100 parts by weight, and the total content is 50 to 150 parts by weight. It is preferable to be a part. Furthermore, it is preferable that the ratio of carbon black in the total reinforcing filler is 0.31 or more and 0.75 or less.
In each of the above embodiments, the seal for the rolling bearing and the hub unit is described. However, the seal of the present invention is a rolling device other than these (for example, a hub unit bearing, a linear guide device, a ball screw, etc. ) Is also suitable.

[Example of hub unit bearing]
Here, an example of an automobile hub unit bearing is shown in FIG.
This automobile hub unit bearing includes an inner ring member 410, an outer ring member 420, a ball 70, a cage 71, and seals 431 and 432. The inner ring member 410 includes a hub 411 into which a shaft is inserted, a flange 412 integrated at one axial end of the outer periphery thereof, and a track member 413 attached to the other end. Reference numeral 411a denotes a spline groove for attaching the shaft. Inner ring raceways 411a and 413a are formed on the outer circumference of the hub 411 and the outer circumference of the raceway member 413, respectively.

The outer ring member 420 is formed by integrating a flange 422 on the outer periphery of a substantially cylindrical outer ring 421, and an outer ring raceway 421a corresponding to the inner ring raceways 411a and 413a is formed.
The hub unit bearing is an inner ring rotating type, a shaft (drive shaft) is inserted into the spline groove 411a of the inner ring member 410, a wheel is attached to the flange 412 of the inner ring member 410, and a suspension device is mounted on the flange 422 of the outer ring member 420. Is attached.

  Seals 431 and 432 seal the space between the inner ring member 410 and the outer ring member 420 at both axial ends of the outer ring member 420 of the hub unit bearing. The seal 432 disposed on the flange 412 side of the inner ring member 410 has, for example, the structure shown in FIG. 5, and the other seal 431 has, for example, the structure shown in FIG.

[Example of seal shape]
The seal of the present invention is one in which the maximum value of the loss tangent (tan δ) in a predetermined temperature range of the rubber molded body forming the lip portion is specified, and the seal shape is not particularly limited. Explained.
FIG. 10 shows a modification of the hub unit with a seal shown in FIG. 3, wherein a bent portion 62a is provided at the outer peripheral end of the flange 62, and a lip portion 33a is slidably contacted with the bent portion 62a. Thus, the sliding contact surface is formed on a spherical surface having a radius R centered on the center of the hub unit or a conical surface contacting the spherical surface. Thus, by providing the sliding surface of the seal on the spherical surface having the radius R centered on the center of the hub unit or the conical surface contacting the spherical surface, the following effects can be obtained.

  Consider the case where the seal of FIG. 10 is used as the seal 431 of FIG. In this case, by using the seal of FIG. 10, the “interference” when the inner ring and the outer ring are in a coaxial state can be reduced. The reason is that the seal shown in FIG. 10 has a small change in “interference”. As a result, even when a relative inclination occurs between the inner ring and the outer ring due to the moment load acting on the hub unit bearing, it is possible to prevent water leakage. Therefore, by using the structure of FIG. 10, both improvement in sealing performance and reduction in torque can be obtained simultaneously.

The seal in FIG. 11 is provided with two elastic bodies 30A and 30B as elastic bodies. In FIG. 11B, as in FIG. 10, the sliding contact surface is provided on a spherical surface having a radius R with the center of the hub unit as the center. For this purpose, the cored bar 20 is provided with a bent portion 20a. The seal of FIG. 11B can obtain the same action as the seal of FIG.
The seal in FIG. 12 has a shape in which a labyrinth space t is provided between the elastic bodies 30A and 30B of the seal in FIG. The sealing performance is further improved than the labyrinth sealing effect. Further, if the sealing property is the same, the “interference” of the lip can be reduced, so that the effect of reducing the torque can be obtained.

FIGS. 13 and 14 are modifications of FIG. 5, and in these cases as well, the sliding contact surface is provided on a spherical surface having a radius R with the center of the hub unit as the center. Therefore, the same action as the seal of FIG. 10 is obtained.
FIG. 15 shows a seal structure composed of two seals 10A and 10B. In FIG. 15B, as in FIG. 10, the sliding contact surface is a spherical surface having a radius R with the center of the hub unit as the center. Provided. For this purpose, the cored bar 21 is provided with a bent portion 21a. The seal of FIG. 15B can obtain the same action as the seal of FIG.
The seal shown in FIG. 16 has the seal structure shown in FIG. 15B and has a shape in which a labyrinth space t is provided between the two seals 10A and 10B. The sealing performance is further improved than the labyrinth sealing effect. Further, if the sealing property is the same, the “interference” of the lip can be reduced, so that the effect of reducing the torque can be obtained.

It is sectional drawing which shows an example of the rolling bearing with a seal | sticker. It is sectional drawing which shows the shape of the lip | rip part of the seal for rolling bearings produced in embodiment. It is sectional drawing which shows an example of the hub unit with the seal. The relationship between the acrylonitrile content in the raw material NBR of each sample produced in the embodiment and the tan δ maximum value (maximum value at an ambient temperature of 20 ° C. to 70 ° C.) measured with a test piece cut out from the hub unit seal. It is a graph to show. It is sectional drawing which shows another example of the hub unit with a seal | sticker. It is a schematic block diagram which shows the muddy water durability test apparatus used in embodiment. It is a graph which shows the relationship between the maximum value of tan-delta in the atmospheric temperature of 20 to 70 degreeC of the elastic body which makes each seal | sticker obtained in embodiment, and a muddy water durable time (relative value). Relationship between the maximum value of tan δ at the atmospheric temperature of 20 ° C. to 70 ° C. of the elastic body forming each seal and the muddy water durability time (relative value) for the sample using the raw rubber G obtained in the embodiment It is a graph which shows. It is sectional drawing which shows an example of the hub unit bearing for motor vehicles. It is sectional drawing which shows the example of a seal structure. It is sectional drawing which shows the example of a seal structure. It is sectional drawing which shows the example of a seal structure. It is sectional drawing which shows the example of a seal structure. It is sectional drawing which shows the example of a seal structure. It is sectional drawing which shows the example of a seal structure. It is sectional drawing which shows the example of a seal structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seal 10 Seal 11 Main part 12 Clamping part 13 Lip part 2 Core metal 20 Core metal 3 Elastic body 30 Elastic body 31 Lip part 32 Lip part (main lip)
33 Lip part 4 Outer ring 40 Outer ring equivalent member 41 Stop groove 5 Inner ring 50 Inner ring equivalent member 50a Hub part 50b Flange part 51 Receiving groove 6 Hub unit 61 Hub 62 Flange 70 Rolling element 100 Seal 200 Core metal 300 Elastic body 301 Radial seal lip part 302 Side seal lip part 303 Side seal lip part

Claims (2)

  The rubber molded body forming the lip part has a maximum loss tangent (tan δ) at a temperature of 10 ° C to 120 ° C of 0.50 or less.   The rubber molded body forming the lip portion has a maximum loss tangent (tan δ) at a temperature of 20 ° C. to 70 ° C. of 0.40 or less.

Images