ROLLING BEARINGS

Abstract

A rolling bearing comprises an inner ring; an outer ring; rolling elements arranged between the inner and outer rings; and an elastic element provided in at least one of openings at both ends in an axial direction of the inner and outer rings, sealing a lubricant around each of the rolling elements. The lubricant is either a silicone oil-based lubricant or a mineral oil-based lubricant, and the elastic element is a vulcanizate of a rubber composition containing epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay. Thus, volume and hardness changes due to lubricant sealing can be reduced, and good wear resistance and hardness can be provided even when the rubber component of the elastic element is epichlorohydrin rubber.

Description

TECHNICAL AREA

[0001] The present invention relates to a rolling bearing and in particular a rolling bearing which contains an elastic element in which epichlorohydrin rubber is used. STATE OF THE ART

[0002] In general, a rolling bearing has an inner ring, an outer ring, and rolling elements arranged between the inner and outer rings. A lubricant is injected into the bearing to provide lubrication. To prevent the lubricant from escaping through an opening between the inner and outer rings, a bearing seal is provided, incorporating an elastic element to seal the opening. This elastic element typically comes into contact with the lubricant as it slides relative to the inner or outer ring, thus requiring the lubricant to possess wear resistance and durability.

[0003] To fulfill the required operational properties of such an elastic element, rubber components such as nitrile rubber (NBR), acrylic rubber (ACM), ethylene acrylate rubber (AEM), fluororubber (FKM), and silicone rubber (VMQ) are conventionally used as the material for the elastic element used in the bearing seal. Improvements have been repeatedly achieved in the application of the rolling bearing, for example, to enhance operational performance.

[0004] Meanwhile, it is known that epichlorohydrin rubber generally possesses good properties such as mechanical strength, heat resistance, low-temperature resistance (cold resistance), ozone resistance, gas permeability, flame retardancy, and oil resistance, but its wear resistance is not necessarily sufficient. Therefore, epichlorohydrin rubber is typically used as a hose material, as described in patent literature (PTL) 1, and is not currently used in practice, for example, as a material for the elastic element used to seal a lubricant for a rolling bearing in automobiles and the like. LIST OF COUNTER-POINTS [PATENT LITERATURE]

[0005] [PTL 1] Japanese published examined application No. S60-33663 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] The inventors of the present invention focused on the above-described good properties of epichlorohydrin rubber and attempted to use epichlorohydrin rubber as a rubber component for an elastic element in a rolling bearing. However, it was found that when an ester-based lubricant containing ester oil is used as the base oil, the volume and hardness of the elastic element change considerably. For example, (i) the considerable volume change leads to unstable sealing interference, and (ii) a reduction in hardness or for some other reason causes the elastic element to soften, thereby increasing the contact area between the elastic element and a bearing ring (race) formed from an inner and an outer ring, resulting in abnormal wear or a reduction in the tightening force.Therefore, it was difficult to use epichlorohydrin rubber as the rubber component of the elastic element of a rolling bearing.

[0007] One object of the present invention is to provide a rolling bearing that can reduce volume change and hardness change due to sealing of a lubricant and exhibits good wear resistance and hardness even in a case where a rubber component of an elastic element is epichlorohydrin rubber. SOLUTION TO THE PROBLEMS

[0008] The inventors conducted a thorough study to solve the aforementioned problems. As a result, it was found that when a silicone oil-based lubricant containing silicone oil or a mineral oil-based lubricant containing mineral oil is used as the base oil, the aforementioned problem can be solved by using epichlorohydrin rubber as the rubber component and including a dispersion improver, a reinforcing material, and modified clay. The present invention has the following core content.

[0009] The present invention relates to a rolling bearing comprising: an inner ring; an outer ring; rolling elements arranged between the inner ring and the outer ring; and an elastic element provided in at least one of openings at both ends in an axial direction of the inner ring and the outer ring, sealing a lubricant around each of the rolling elements. The lubricant is one of a silicone oil-based lubricant and one of a mineral oil-based lubricant, and the elastic element is a vulcanizate of a rubber composition comprising epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay.

[0010] According to one embodiment of the present invention, the rubber composition may contain 1.0 to 3.0 parts by weight of the dispersion improver, 25 to 35 parts by weight of the reinforcing material and 40 to 80 parts by weight of the modified clay in relation to 100 parts by weight of the rubber component.

[0011] According to one embodiment of the present invention, the dispersion improver is a coupling agent.

[0012] According to one embodiment of the present invention, the reinforcing material is silica.

[0013] According to one embodiment of the present invention, the modified clay is silane-modified clay, which is a surface-treated product obtained by performing a surface treatment on clay with a silane-based coupling agent.

[0014] In the embodiments of the present invention, the configurations of the embodiments described above can be combined arbitrarily. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0015] The present invention can provide a rolling bearing that reduces volume change and hardness change due to sealing of a lubricant and has good wear resistance and hardness even in a case where the rubber component of the elastic element is epichlorohydrin rubber. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. Figure 1 is a cross-sectional view of a rolling bearing according to an embodiment of the present invention. [ Fig. 2] Fig. Figure 2 is an enlarged cross-sectional view of a main part area in Fig. 1. [ Fig. 3] Fig. 3 presents a method for performing a wear resistance test. DESCRIPTION OF EXECUTION FORMS

[0016] A rolling bearing according to one embodiment of the present invention comprises an inner ring, an outer ring, rolling elements arranged between the inner ring and the outer ring, and an elastic element provided in at least one of openings at both ends in an axial direction of the inner ring and the outer ring, and a lubricant sealed around each of the rolling elements. The lubricant is a silicone oil-based lubricant or a mineral oil-based lubricant. The elastic element is a vulcanizate of a rubber composition comprising epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay.

[0017] When a silicone oil-based or mineral oil-based lubricant is used, its impact on the epichlorohydrin rubber is reduced, thereby minimizing volume and hardness changes (particularly a decrease in hardness) of the elastic element compared to using an ester oil-based lubricant. Furthermore, a dispersion improver is used in combination with a reinforcing material and modified clay to enhance the dispersibility of the reinforcing material and modified clay within the epichlorohydrin rubber. This provides mechanical strength, such as tensile strength and elongation at break, which are beneficial properties of epichlorohydrin rubber, and can also improve the abrasion resistance and hardness of the elastic element.Here, hardness refers to Shore A hardness, which can be measured using a method described in the examples described later.

[0018] The embodiments of the rubber composition used for the elastic element are described below.

[0019] As described above, the rubber composition contains epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay. Epichlorohydrin rubber is one of the rubber components of the composition. In other words, the rubber composition contains no other rubber components besides epichlorohydrin rubber. Examples of epichlorohydrin rubber include a homopolymer of epichlorohydrin (which can be abbreviated as CO), a copolymer of epichlorohydrin and ethylene oxide (which can be abbreviated as ECO), a copolymer of epichlorohydrin and allyl glycidyl ether (which can be abbreviated as GCO), and a copolymer of epichlorohydrin, ethylene oxide, and allyl glycidyl ether (which can be abbreviated as GECO). Any of these can be used. Among them, CO and ECO are preferable.Furthermore, epichlorohydrin derived from a plant material can be used. By using such epichlorohydrin obtained from a plant-derived material, the epichlorohydrin rubber can be an environmentally friendly rubber component. From an environmental perspective, epichlorohydrin derived from a plant material is preferably used, and even more preferably a homopolymer (CO) of epichlorohydrin derived from a plant material is used. The proportion of the rubber component in the rubber composition can be determined as is suitable, for example, according to the application of the rolling bearing, and can be, for example, 35 to 75 wt% of the total rubber composition.

[0020] The dispersion improver is not subject to any particular restrictions as long as it can improve the dispersibility of the reinforcing material and the modified clay in the epichlorohydrin rubber, and the dispersion improver can be selected according to the types of reinforcing material and modifier as appropriate. Examples of such a dispersion improver include a coupling agent and a surfactant. Among them, a coupling agent is preferred from the point of view of improving dispersibility and wear resistance. Examples of the coupling agent include a silane-based coupling agent, such as a vinyl-based silane coupling agent, an amino-based silane coupling agent, an epoxy-based silane coupling agent, and a mercapto-based silane coupling agent, a zirconia-based coupling agent, a titanate-based coupling agent, and an aluminate-based coupling agent.Among them, the silane-based coupling agent is preferred, and the mercapto-based silane coupling agent is particularly preferred. Examples of the mercapto-based silane coupling agent include a mercapto-based silane coupling agent in which 1 to 3 mercapto groups (-SH) or 1 to 3 functional groups containing mercapto groups directly bond with Si. Examples of the functional group containing a mercapto group include a C1 to C6 hydrocarbon group substituted by a mercapto group. The hydrocarbon group can be saturated or unsaturated, but a saturated hydrocarbon group is preferred. The structure of the hydrocarbon group can be linear or branched, but a linear structure is preferred.The silane-based coupling agent preferably has an alkoxy group, and examples of the alkoxy group contain a methoxy group and an ethoxy group, with a methoxy group being preferred. The number of alkoxy groups can be anything from 1 to 3. One type of dispersion improver can be used alone, or two or more types of dispersion improvers can be used in combination.

[0021] The proportion of the dispersion improver in the rubber composition can be determined according to the intended use of the rolling bearing or the like, as appropriate. From the perspective of dispersibility and wear resistance, the proportion of the dispersion improver is preferably 0.5 to 5.0 parts by weight and more preferably 1.0 to 3.0 parts by weight per 100 parts by weight of the rubber component.

[0022] The reinforcing material is not subject to any particular restrictions as long as it can improve the wear resistance and hardness of the elastic element in combination with the modified clay. Examples of reinforcing material include silica, calcium carbonate, barium sulfate, clay (excluding modified clay), a fiber, an organic reinforcing agent, and an organic filler. One type of reinforcing material may be used alone, or two or more types of reinforcing materials may be used in combination. Among the specific examples of reinforcing materials, silica is particularly preferred. The silica should be silicon dioxide or a substance formed from silicon dioxide. Examples of silica include wet silica, pyrogenic silica, diatomaceous earth, and silicates such as magnesium silicate.Among them, silica is preferably silicon dioxide, such as wet silica and pyrogenic silica.

[0023] The proportion of reinforcing material in the rubber composition can be determined according to the intended use of the rolling bearing or the like. With regard to wear resistance and improving the hardness of the elastic element, the proportion of reinforcing material is preferably 15 to 35 parts by weight and more preferably 25 to 35 parts by weight, based on 100 parts by weight of the epichlorohydrin rubber.

[0024] The modified clay is not subject to any particular restrictions as long as it can improve the wear resistance and hardness of the elastic element in combination with the reinforcing material. Examples of such modified clay include silane-modified clay. The silane-modified clay is preferably a product obtained by performing a surface treatment on clay with a silane-based coupling agent (surface-treated product). The clay used for the treatment can, for example, be calcined at 600°C. Commercially available silane-modified clay can be used as such, and examples include BURGESS KE, manufactured by BURGESS.

[0025] The proportion of modified clay in the rubber composition can be determined according to the intended use of the rolling bearing or the like. From the perspective of wear resistance and improved hardness of the elastic element, the proportion of modified clay is preferably 10 to 100 parts by weight and more preferably 40 to 80 parts by weight per 100 parts by weight of the epichlorohydrin rubber.

[0026] Components other than those described above can be mixed with the rubber compound. Examples of such components include a vulcanizing agent, a vulcanization accelerator, a stabilizer, an anti-aging agent, a lubricating oil, a softening agent, a dye, a processing aid, and a burn-in inhibitor.

[0027] Examples of vulcanizing agents include: sulfur; quinoxaline-based vulcanizing agents such as 2,3-dimercaptoquinoxaline, quinoxaline-2,3-dithiocarbonate, 6-methylquinoxaline-2,3-dithiocarbonate, and 5,8-dimethylquinoxaline-2,3-dithiocarbonate; 2,4,6-trimercapto-s-triazine; thiurams such as tetramethylthiuram monosulfide (TMTS), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), and dipentamethylenethiuram tetrasulfide (DPTT); and sulfur-based vulcanizing agents such as 4,4'-dithiodimorpholine. One of these can be used alone, or two or more can be used in combination. The proportion of vulcanizing agent is preferably 0.5 to 10 parts by weight per 100 parts by weight of the epichlorohydrin rubber.

[0028] Examples of vulcanization accelerators include guanidine compounds, imidazole compounds, quaternary onium salts, tertiary amine compounds, tertiary phosphine compounds, and alkali metal salts of weak acids. Examples of guanidine compounds include 1,3-diphenylguanidine and 1,3-di-o-tolylguanidine. Examples of imidazole compounds include 2-methylimidazole and 2-phenylimidazole. Examples of quaternary onium salts include tetra-n-butylammonium bromide and octadecyltri-n-butylammonium bromide. Examples of tertiary amine compounds include triethylenediamine and 1,8-diaza-bicyclo[5,4,0]undecen-7. Examples of tertiary phosphine compounds include triphenylphosphine and trip-p-tolylphosphine. Examples of alkali metal salts of a weak acid include inorganic salts of weak acids such as phosphate of sodium or potassium and carbonate, and organic salts of weak acids such as stearate and laurate.The proportion of the vulcanization accelerator is preferably 0.1 to 5 parts by weight per 100 parts by weight of the epichlorohydrin rubber.

[0029] Examples of stabilizers include magnesium oxide, hydrotalcite, zeolites, calcium oxide, aluminum oxide, basic silicon dioxide, and magnesium hydroxide. One of them can be used alone, or two or more can be used in combination.

[0030] The rubber composition can be obtained by mixing the essential components described above and any other components to be used as needed in a desired ratio and then kneading the mixture uniformly. Any conventionally known kneading method can be used. For example, a method for uniform kneading using a closed-type kneader, such as a kneader or a Banbury mixer, or an open-type kneader, such as a roller, can be employed.

[0031] The elastic element according to the embodiment can, for example, be obtained as a vulcanizate (molded product) of the rubber composition with a predetermined shape by vulcanizing and shaping the rubber composition obtained as described above at a predetermined temperature by a molding process such as compression molding, injection molding, extrusion molding or calender molding.

[0032] In the elastic element produced by vulcanizing the rubber composition described above, the rubber component can be epichlorohydrin rubber. Even with such a rubber component, if the lubricant sealed in the rolling bearing is a specific lubricant, the influence of the lubricant is reduced without impairing most of the good properties of the epichlorohydrin rubber itself. Even when such an elastic element is in contact with the specific lubricant, changes in volume and hardness (especially a reduction in hardness) are inhibited, thus maintaining good hardness, and the elastic element also exhibits good wear resistance. Therefore, such an elastic element can be used in various rolling bearings as long as the specific lubricant is used.For example, the elastic element is suitable for a rolling bearing for automobiles, which has an elastic element for sealing a silicone oil-based lubricant for electrical devices for automobiles and accessories.

[0033] A rolling bearing according to one embodiment, in which the elastic element described above is used, will be described below with reference to the drawings. In the following description, the direction of the axis of rotation will be referred to as the "axial direction" and the direction of the radius of rotation as the "radial direction".

[0034] Fig. 1 and Fig.Figure 2 shows a rolling bearing 1 with a bearing seal 11 attached to it. In the rolling bearing 1, an inner ring 2 and an outer ring 3 rotate relative to each other on rolling elements 5, which are held by a holder 4. A lubricant 10 is sealed between the inner ring 2 and the outer ring 3. At both ends of the rolling elements 5 in the axial direction (left and right sides in the bearing width direction), bearing seals 11, 11, each having an almost ring-shaped form when viewed from the front, are arranged such that they seal annular openings (annular openings) A, A at both ends in the axial direction between the inner ring 2 and the outer ring 3.

[0035] The lubricant is a silicone oil-based lubricant or a mineral oil-based lubricant, as described above. The lubricant can be liquid lubricating oil or semi-solid or solid grease, but it is preferably grease. In the case of grease, the base oil is silicone oil or mineral oil, and various thickeners and the like are included. The thickener can be a well-known substance, and examples of thickeners include metallic soaps such as lithium soap and urea.

[0036] The bearing seal 11 can be a single-shield type for sealing only one side of the rolling bearing 1, depending on the application, instead of a double-shield type for sealing the annular openings A, A of the rolling bearing 1 on both sides, as described in Fig.As shown in Figure 1, the bearing seal 11 is arranged at at least one of the annular openings A, A on the left and right sides in the bearing width direction between the inner ring 2 and the outer ring 3 of the rolling bearing 1.

[0037] As it is in Fig.As shown in Figure 2, in the bearing seal 11, an outer circumferential section and an inner circumferential section of an annular metallic core metal 12 formed from a steel plate or the like are continuously covered by an elastic element 13, as described above, for example by vulcanization adhesion. The inner circumferential lateral end section of the elastic element 13 is formed as a lip seal 14, and the outer circumferential lateral end section is formed as an outer diameter mounting section 15. A contact lip (main lip) 14A on the inside of the lip seal 14 in the axial direction is brought into pressure contact with a side wall surface 8 that extends in the radial direction of the inner ring 2. This prevents the lubricant 10 filled into the bearing 1 from leaking out and also prevents foreign substances from penetrating from the outside.A non-contacting lip (dust lip) 14b on the outside of the lip seal 14 in the axial direction lies opposite the outer circumferential surface of the inner ring 2 on the outside of an inner ring circumferential groove 6 extending in the circumferential direction, which is also called a sealing groove, formed in the outer circumferential surface of the inner ring 2, with a small gap between them, and by means of a labyrinth sealing effect a foreign body can thus be prevented from penetrating from the outside.

[0038] At the in Fig.In the embodiment shown in Figure 2, a constricted section 16 is formed in the bearing seal 11 between an inner circumferential surface 12A of the core metal 12 and the lip seal 14. In a state where the bearing seal 11 is attached to the outer ring 3, the contact lip 14a of the lip seal 14 is brought into pressure contact with the side wall surface 8 of the inner ring 2, as described above. For the structure of such pressure contact, the shapes, dimensions, positions, and the like of the lip seal 14 and the constricted section 16 can be determined according to a predetermined method, as is suitable, such that, taking into account a balance with respect to lip position variation due to centrifugal force from a rotation of the outer ring 3, the centrifugal forces on the contact lip 14a and the non-contacting lip 14b are nearly equal to each other during a rotation of the outer ring 3.The balance is thus considered to prevent a condition in which the attracting force of the contact lip 14a with respect to the side wall surface 8 is reduced, thereby increasing the gap between the non-contacting lip 14b and the inner ring 2 and allowing dust to easily enter, or a condition in which the contact lip 14a is away from the side wall surface 8, thus creating a gap that would allow the lubricant 10 to escape or allow dust, water, or similar substances to penetrate from the outside. Furthermore, the lip seal 14 and the constricted section 16 are each elastic elements formed from a cured product of the rubber composition described above. Accordingly, in a case where a predetermined lubricant is used, properties such as mechanical strength (tensile strength, elongation at break, etc.) are not affected.), derived from epichlorohydrin rubber, and its hardness and wear resistance are also good. Therefore, a preferential pressure contact between the contact lip 14a and the side wall surface 8 is continuously maintained in conjunction with the structure of the lip seal 14, thus preventing a shortened service life of the rolling bearing.

[0039] As it is in Fig. As shown in Figure 2, it is preferable that the bearing seal 11 has a projection 17 which extends inwards from the end face 12A of the core metal 12 in the direction of the bearing and a small gap is formed between the projection 17 and the end edge of the side wall surface 8, i.e. the end edge in the direction of the outer ring, and thus a labyrinth effect prevents the lubricant from flowing in the direction of the contact lip 14a.

[0040] As it is in Fig.As shown in Figure 2, the outer diameter mounting section 15 is fitted into an outer ring circumferential groove 7, which is formed in the inner circumferential surface of the outer ring 3. This serves to position and fix the bearing seal 11 relative to the bearing 1 and to prevent foreign substances from entering from the outer diameter section of the bearing seal 11. Furthermore, the outer diameter mounting section 15 is also the elastic element formed from the cured product of the rubber composition described above, so that adhesion between the outer diameter mounting section 15 and the outer ring circumferential groove 7 can preferably be maintained, thus effectively preventing the ingress of foreign substances.

[0041] In the present embodiment, the elastic element described above is applied to the rolling bearing, which has a structure in which the contact lip 14a of the lip seal 14 is constantly in pressure contact with the side wall surface 8 of the inner ring 2. However, the present invention is not limited to such an embodiment. For example, the elastic element, which is the vulcanizate of the rubber composition described above, can also be applied to an elastic element that acts as a contact seal to seal the rolling bearing in a case where the rotational speed of the outer ring is relatively low, and that acts as a non-contact seal itself in a state where the lip seal is away from the inner ring, in a case where the rotational speed of the outer ring is relatively high, as described in Japanese unexamined patent application publication No. 2010-265968.Especially when the elastic element acts as a contact seal, the elastic element has good hardness and can exhibit good wear resistance. EXAMPLES

[0042] The elastic element applicable to a rolling bearing according to the embodiment of the present invention will be described in detail below. (Test example 1): Testing for oil resistance to silicone oil-based lubricant and mineral oil-based lubricant<Vorbereitung eines elastischen Elements>

[0043] 100.0 parts by weight of epichlorohydrin rubber (manufactured by Zeon Corporation, Hydrin H75, CO), 1.8 parts by weight of a vulcanizing agent (manufactured by Sankyo Kasei Co., Ltd., ZISNET F, 2,4,6-trimercapto-s-triazine), 0.6 parts by weight of vulcanization accelerator (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, SOXINOL DG, 1,3-diphenylguanidine), 1.0 part by weight of a dispersion improver (manufactured by Momentive, A-189, silane coupling agent, γ-mercaptopropyltrimethoxysilane), 30.0 parts by weight of a reinforcing material (TOSOH SILICA CORPORATION, Nipsil ER, silicon dioxide), and 60.0 parts by weight of modified clay (manufactured by BURGESS, BURGESS KE, Silane-modified clay) were mixed and kneaded in an 8-inch open roller to obtain a rubber composition.The resulting rubber composition was used to carry out primary vulcanization (150 to 180°C for 10 to 15 minutes) and secondary vulcanization (150 to 180°C for 1 to 10 hours), and the resulting product was formed into a layered mold. This yielded a rubber sheet (rubber molding product, hereinafter referred to as the "elastic element") with a thickness of 2 mm. < Pull test>

[0044] The elastic element obtained was used to measure its tensile strength and elongation at break according to JIS K 6251. The measurement results were 14.2 MPa and 570% respectively, thus confirming the elastic element's suitability for use in rolling bearings. <Oil resistance test>

[0045] The resulting elastic element was used to measure its hardness (Shore A hardness) according to JIS K 6253-3 and its volume according to JIS K 6258. The elastic element was then immersed in a mineral oil-based, silicone oil-based, or ester oil-based lubricant at 150°C for 72 hours. Afterward, the hardness and volume were measured simultaneously, and the change in hardness (ΔShore A) and the rate of change in volume (ΔV) were determined according to the following equation. The oil resistance was then evaluated. ΔShore−A=(Shore−A−hardness after immersion in the lubricant)−(Shore−A−hardness before immersion in the lubricant) ΔV(%)=[(Volume after immersion in the lubricant / Volume before immersion in the lubricant)−1]×100

[0046] The evaluation criteria were as follows.

[0047] In a case where ΔShore A was -20 or more and 20 or less, it was possible to reduce the extent of wear, and practical use is possible.

[0048] In a case where ΔV was -5% or more and 20% or less, the change in bearing seal interference was small, the torque was stable, and practical use is possible.

[0049] Table 1 shows evaluation results and lubricants used. The manufacturers / distributors of the lubricants listed in Table 1 are as follows: Alvania S: Shell Lubricants Japan KK, Raremax AF-I: KYODO YUSHI CO., LTD, G40M: Shin-Etsu Chemical Co., Itd., MOLYKOTE 44M: Toray Dow Corning Corp., HQ72-102: NOK KLÜBER CO., LTD., Multemp SRL: KYODO YUSHI CO., LTD. [Table 1] Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Lubricant (grease) Product name Alvania S RaremaxAF-I G40M MOLYKOTE44M HQ72-102 MultempSRL component base oil mineral oil mineral oil silicone oil silicone oil Ester oil Ester oil Thickener Lithium soap urea Lithium soap Lithium soap Lithium soap urea Hardness change ΔShore-A +2 +3 +1 +3 -23 -24 Rate of volume change (72 hours) ΔV[%] +4,3 +3,0 -2,1 -4,0 +27,7 +27,2 Evaluation Good Good Good Good Bad Bad (Test example 2): Investigation of the amount of dispersion improver added<Vorbereitung eines elastischen Elements>

[0050] Rubber sheets (molded rubber products, hereinafter referred to as “elastic element”) with a thickness of 2 mm were prepared in the same way as in test example 1, except that components were mixed with the respective mixing ratios as shown in Table 2. <Verschleißtest>

[0051] A test piece was produced using a respective elastic element. Fig. Figure 3 shows a wear resistance tester in which the test piece was rotated while a load was applied to it from above via a friction plate. The extent of wear (mm) on the test piece was then measured. The test conditions were: load 200 gf, rotation speed 10,000 rpm, and time 15 minutes.

[0052] The evaluation criteria were as follows. "Poor" indicates that practical use is impossible. Good: less than 0.10 mm Appropriate: 0.10 mm or more and 0.30 mm or less Bad: more than 0.30 mm <dispergierbarkeitstest>

[0053] The resulting elastic element was used to cut out a JIS No. 3 bar sample, with the longitudinal direction being the rolling direction, in accordance with JIS K 6251. Images of two surfaces within a range corresponding to the distance between the marking lines (both sides within a range of 20 mm as the distance between the marking lines, and 2 mm in the thickness direction) were taken with a digital microscope on the cut surfaces of the resulting bar sample. The sizes of the dispersed objects from which the images were taken were measured, and the dispersibility was tested.

[0054] The evaluation criteria for dispersibility were as follows. “Poor” indicates that practical use is impossible.

[0055] Good: Dispersed objects with sizes of 0.029 mm or less were merely observed while the images were being taken.

[0056] Adequate: One or more dispersed objects with sizes greater than 0.029 mm and 0.049 mm or less were observed while the images were being taken.

[0057] Bad: One or more dispersed objects larger than 0.049 mm were observed while the images were being taken.

[0058] Table 2 shows evaluation results. [Table 2] Example Comparative example 5 6 7 8 9 3 rubber component Hydrin H75 100,0 100,0 100,0 100,0 100,0 Hydrin H55 100,0 Vulcanizing agent ZISNET F 1,8 1,8 1,8 1,8 1,8 1,8 Vulcanization accelerator SOXINOL DG 0,6 0,6 0,6 0,6 0,6 0,6 Dispersion improver A-189 0,5 1,0 1,0 3,0 5,0 - Reinforcement material Nipsil ER 30,0 30,0 30,0 30,0 30,0 30,0 Modified tone BURGESS KE 60,0 60,0 60,0 60,0 60,0 60,0 Wear test Extent of wear [mm] 0,12 0,06 0,08 0,06 0,1 0,32 Evaluation Appropriate Good Good Good Appropriate Bad Dispersibility test Evaluation Appropriate Good Good Good Appropriate Bad (Test example 3): Checking for the added amount of modified tone<Vorbereitung eines elastischen Elements>

[0059] Rubber sheets (rubber molded products, hereinafter referred to as “elastic element”) with a thickness of 2 mm were prepared in the same way as in test example 1, except that the components were mixed with the respective mixing ratios as shown in Table 3. <Verschleißtest>

[0060] A wear test was performed and an evaluation was carried out in the same way as in test example 2. <Härteprüfung>

[0061] The resulting elastic element was used to measure its hardness (Shore A hardness) according to JIS K 6253-3, and an evaluation was performed. The evaluation criteria were as follows: "Poor" indicates that practical use is impossible. Excellent: Shore A hardness was 65 or more and 75 or less. Good: Shore A hardness was 60 or higher and less than 65. Appropriate: Shore A hardness was greater than 75 and 85 or less. Bad: Shore A hardness was less than 60 or more than 85.

[0062] Table 3 shows evaluation results. [Table 3] Example 10 11 12 13 14 15 16 17 18 rubber component Hydrin H75 100,0 100,0 100,0 100,0 100,0 100,0 100,0 100,0 100,0 Vulcanizing agent ZISNET F 1,8 1,8 1,8 1,8 1,8 1,8 1,8 1,8 1,8 Vulcanization accelerator SOXINOL DG 0,6 0,6 0,6 0,6 0,6 0,6 0,6 0,6 0,6 Dispersion improver A-189 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Reinforcement material Nipsil ER 30,0 30,0 30,0 30,0 30,0 30,0 30,0 30,0 30,0 Modified tone BURGESS KE 10,0 20,0 30,0 40,0 50,0 60,0 70,0 80,0 90,0 Wear test Extent of wear [mm] 0,30 0,25 0,15 0,05 0,07 0,06 0,07 0,075 0,08 Evaluation Appropriate Appropriate Appropriate Good Good Good Good Good Good Hardness test Shore A hardness 61 63 65 65 66 70 72 74 76 Evaluation Good Good Excellent Excellent Excellent Excellent Excellent Excellent Appropriate (Test example 4): Examination for added or additional amount of reinforcing material<Vorbereitung eines elastischen Elements>

[0063] Rubber sheets (molded rubber products, elastic elements) with a thickness of 2 mm each were prepared in the same way as in test example 1, except that the components were mixed with the respective mixing ratios as shown in Table 4. <Verschleißtest>

[0064] A wear test was performed and an evaluation was carried out in the same way as in test example 3. <Härteprüfung>

[0065] A hardness test was carried out and an evaluation was performed in the same way as in test example 3.

[0066] Table 4 shows evaluation results. [Table 4] Example 19 20 21 22 23 rubber component Hydrin H75 100,0 100,0 100,0 100,0 100,0 Vulcanizing agent ZISNET F 1,8 1,8 1,8 1,8 1,8 Vulcanization accelerator SOXINOL DG 0,6 0,6 0,6 0,6 0,6 Dispersion improver A-189 1,0 1,0 1,0 1,0 1,0 Reinforcement material Nipsil ER 15,0 20,0 25,0 35,0 40,0 Modified tone BURGESS KE 60,0 60,0 60,0 60,0 60,0 Wear test Extent of wear [mm] 0,30 0,25 0,10 0,07 0,05 Evaluation Appropriate Appropriate Good Good Good Hardness test Shore A hardness 62 62 65 75 80 Evaluation Good Good Excellent Excellent Appropriate

[0067] In the elastic element containing the predetermined component, the rubber component can be epichlorohydrin rubber. Even in such a case, when a silicone oil-based or mineral oil-based lubricant is used, the hardness change (Shore A hardness) and volume change rate are lower than in a case where an ester oil-based lubricant is used, and the elastic element is, according to Table 1, applicable to a rolling bearing. According to Table 2, in a case where the elastic element contains the dispersion improver, the dispersibility of the reinforcing material and the modified clay is good, and the wear resistance is at a level that allows the elastic element to be applied to rolling bearings without problems.According to Tables 3 and 4, in a case where the elastic element contains the reinforcing material and the modified clay, the wear resistance and hardness are at a level that allows the elastic element to be used practically without problems in rolling bearings. Therefore, according to Tables 1 to 4, a rolling bearing containing the predetermined elastic element is preferable for use as a rolling bearing in various applications, such as automobiles, when a silicone oil-based or a mineral oil-based lubricant is used. DESCRIPTION OF REFERENCE MARKS A ring-shaped opening 1 rolling bearing 2 inner ring 3 Outer ring 4 holders 5 rolling elements 6 Inner ring circumferential groove 7 Outer ring circumferential groove 8 side wall area 9 External perimeter area 10 Lubricants (Grease) 11 Bearing seal 12 Core metal 12A Inner circumferential area 13 elastic element 14 Lip seal 14a Contact lip 14b non-contact lip (dust lip) 15 Outer diameter mounting part range 16 narrowed sub-area 17 lead QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 60-33663

[0005] JP 2010-265968

[0041] < / dispergierbarkeitstest>

Claims

[1] Rolling bearings, comprising: an inner ring; an outer ring; Rolling elements arranged between the inner ring and the outer ring; and an elastic element provided in at least one of openings at both ends in an axial direction of the inner ring and the outer ring, and sealing a lubricant around each of the rolling elements, wherein the lubricant is a silicone oil-based lubricant and a mineral oil-based lubricant, and The elastic element is a vulcanizate of a rubber composition containing epichlorohydrin rubber, a dispersion improver, a reinforcing material, and modified clay. [2] Rolling bearing according to claim 1, wherein the rubber composition comprises 1.0 to 3.0 parts by weight of the dispersion improver, 25 to 35 parts by weight of the reinforcing material and 40 to 80 parts by weight of the modified clay in relation to 100 parts by weight of the epichlorohydrin rubber. [3] Rolling bearings according to claim 1 or 2, wherein the dispersion improver is a coupling agent. [4] Rolling bearings according to claim 1 or 2, wherein the reinforcing material is silica. [5] Rolling bearings according to claim 1 or 2, wherein the modified clay is silane-modified clay which is a surface-treated product obtained by performing a surface treatment of clay with a silane-based coupling agent.

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