Grease composition and rolling device filled with grease composition

Abstract

To provide: a grease composition comprising vegetable oil such as soybean oil, rapeseed oil, rice bran oil, castor oil or palm oil as base oil, and a plant-derived biomass carbon produced by a special production method as a thickener using a raw material, i. e., vegetable oil such as castor oil or pine resin oil; and a rolling device with an internal space filled with the grease composition.SOLUTION: The grease composition comprises at least base oil and a thickener, the base oil being constituted of vegetable oil, and the thickener being constituted of biomass carbon black. The rolling device is characterized in that vitamin E of natural origin is blended as an antioxidant in the grease composition. The internal space of the rolling device is filled with the grease composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an improvement in a grease composition filled in the internal space of a rolling device. [Background technology]

[0002] Conventionally, grease compositions filled into the internal space of rolling devices have generally been those that use mineral oil or synthetic oil as the base oil and various metal soaps or urea as the thickener. Furthermore, in consideration of the environment, vegetable oil-based greases have also been used, and those that use carbon black as the thickener to impart electrical conductivity have also been commonly used (see Patent Document 1).

[0003] However, this carbon black is made from coal-based or petroleum-based heavy oils that are rich in aromatic components, and is not environmentally friendly. Furthermore, coal-based and petroleum-based heavy oils are finite, non-renewable resources, but because the world is dependent on these resources, global efforts are being made to reduce their dependence on non-renewable resources. One example of this is the adoption of the Sustainable Development Goals (SDGs), which aims to move away from non-renewable resources (fossil fuels). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-109905 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve these problems associated with the prior art, and its object is to provide a grease composition that uses a vegetable oil such as soybean oil, rapeseed oil, rice bran oil, castor oil, or palm oil as a base oil, uses vegetable oils such as castor oil or rosin oil as a raw material, and uses plant-derived biomass carbon produced by a special manufacturing method as a thickener, and a rolling device whose internal space is filled with this grease composition. [Means for solving the problem]

[0006] To achieve this object, the first invention is characterized in that, in a grease composition comprising at least a base oil and a thickener, the base oil is composed of vegetable oil and the thickener is composed of biomass carbon black.

[0007] The second invention is characterized in that the grease composition of the first invention further contains naturally occurring vitamin E as an antioxidant.

[0008] The third invention is a rolling device characterized in that the grease composition according to the first invention or the second invention is filled into an internal space.

[0009] A fourth aspect of the present invention is that the rolling device of the third aspect of the present invention is a rolling bearing.

[0010] The fifth aspect of the present invention is that the rolling device of the third aspect of the present invention is a linear guide device.

[0011] A sixth aspect of the present invention resides in that the rolling device of the third aspect of the present invention is a ball screw. [Effects of the Invention]

[0012] The grease composition of the present invention uses biomass carbon black made from vegetable oil as a thickener, making it more bio-based than conventional products that use carbon black derived from coal or petroleum. Furthermore, by using vegetable oil as the base oil, even when other additives are included, the biomass content is nearly 100%, making it environmentally friendly and contributing to carbon neutrality. As a result, rolling devices whose internal spaces are filled with this biomass grease composition can also be environmentally friendly. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic partial cross-sectional view of a rolling bearing, which is one embodiment of a rolling device, filled with the grease composition of the present invention. [Figure 2] 1 is a schematic perspective view of a linear guide device, which is one embodiment of a rolling device filled with the grease composition of the present invention. FIG. [Figure 3] 1 is a schematic partial side view, partially cut away, showing a ball screw, which is one embodiment of a rolling device filled with the grease composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention provides a grease composition comprising at least a base oil and a thickener, characterized in that the base oil is a vegetable oil and the thickener is biomass carbon black, and further, the grease composition contains naturally occurring vitamin E as an antioxidant. The grease composition of the present invention is filled into an internal space of a rolling device, and examples of the rolling device include a rolling bearing, a linear guide device, and a ball screw. These embodiments will be described below in order. Note that this embodiment is merely one embodiment of the present invention and should not be construed as being limited in any way, and appropriate design modifications are possible within the scope of the present invention.

[0015] First Embodiment This embodiment shows, as an example of an embodiment of a rolling device, a deep groove ball bearing as shown in Fig. 1. This deep groove ball bearing includes an inner ring 1, an outer ring 3, a plurality of rolling elements (balls) 5 arranged to roll freely between the inner ring 1 and the outer ring 3, a cage 7 that holds the rolling elements 5 between the inner ring 1 and the outer ring 3, and an annular rubber seal device 9 attached to the seal groove 3a of the outer ring 3 and interposed between the inner ring 1 and the outer ring 3.

[0016] The rubber seal device 9 is formed by vulcanizing and bonding a reinforcing member (seal core) 11, to which a vulcanizing adhesive has been applied in a semi-cured state, and an unvulcanized rubber composition in a mold having an internal space, by applying pressure and heating, and integrating the reinforcing member 11 and the elastic member (seal member) 13.

[0017] In order to improve adhesion, a zinc-plated steel sheet whose surface has been further subjected to a chemical conversion treatment such as zinc phosphate treatment is preferably used as the reinforcing member 11. Note that the reinforcing member 11 is not limited to the configuration of this embodiment, and can be modified in design within the scope of the present invention.

[0018] The inner space A of the deep groove ball bearing, which is a bearing space sealed by the seal member 13 and formed by the inner ring 1, the outer ring 3 and the rolling elements 5, is filled with the grease composition of the present invention.

[0019] In this embodiment, a deep groove ball bearing has been described as an example of a rolling bearing, but the present invention can be applied to various other types of rolling bearings, such as radial rolling bearings such as angular contact ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust rolling bearings such as thrust ball bearings and thrust roller bearings.

[0020] Next, the plant-derived biomass carbon black used in the grease composition of the present invention will be described in detail. Conventional carbon black is mass-produced using coal-based or petroleum-based heavy oils, which are rich in aromatic components, as raw materials, and various properties are controlled by incomplete combustion of these raw materials. When these raw materials were replaced with vegetable oils such as castor oil or rosin oil, mass production was not possible due to the low content of aromatic components. However, by improving manufacturing technology, it has become possible to mass-produce biomass carbon black using vegetable oils as raw materials. Therefore, in the present invention, biomass carbon black, which has become mass-producible, is contained as a filler (reinforcing agent) in the rubber material.

[0021] In the grease composition of the present invention, a vegetable oil selected from soybean oil, rapeseed oil, rice bran oil, castor oil, and palm oil is used as the base oil. In order to improve the heat resistance of these vegetable oils, it is preferable to add naturally occurring vitamin E.

[0022] In addition, various additives such as extreme pressure additives, anti-wear agents, and anti-rust agents may also be contained. It is more preferable to use sulfurized oil produced based on vegetable oil such as soybean oil or rapeseed oil as the extreme pressure additive.

[0023] In addition, the sealing member is also made of a rubber composition containing plant-derived biomass carbon produced using vegetable oil as a filler (reinforcing agent), making it possible to provide a rolling device using this environmentally friendly rubber sealing device, which will be described below.

[0024] A rubber composition constituting a sealing member of a rubber seal device or the like contains plant-derived biomass carbon black as a filler. Conventional carbon black is mass-produced using coal-based or petroleum-based heavy oils, which are rich in aromatic components, as raw materials, and various properties are controlled by incomplete combustion of these raw materials. When these raw materials were replaced with vegetable oils such as castor oil or rosin oil, mass production was not possible due to the low aromatic component content. However, by improving manufacturing technology, it has become possible to mass-produce biomass carbon black using vegetable oils as raw materials. Therefore, biomass carbon black, which has become mass-produced, is included as a filler (reinforcing agent) in rubber materials.

[0025] The base rubber of the rubber composition forming the sealing member 13 of the rubber seal device 9 is selected from acrylonitrile butadiene rubber, hydrogenated acrylonitrile butadiene rubber, acrylic rubber, fluororubber, silicone rubber, etc., depending on the heat resistance and oil resistance required of the rolling device.

[0026] The base rubber of the rubber composition forming the sealing member is selected from acrylonitrile butadiene rubber, hydrogenated acrylonitrile butadiene rubber, acrylic rubber, fluororubber, silicone rubber, etc., depending on the heat resistance and oil resistance required for the rolling device.

[0027] For special applications requiring chemical resistance to brake fluid, ethylene propylene non-conjugated diene rubber (terpolymer) is used. This ethylene propylene non-conjugated diene rubber (terpolymer) is a non-conjugated diene that can be vulcanized with ethylene, propylene, and sulfur as monomer components. The proportions of each monomer are 40 to 80% by weight of ethylene, 15 to 60% by weight of propylene, and 3 to 15% by weight of non-conjugated diene. Ethylidene norbornene (5-ethylidene-2-norbornene), dicyclopentadiene, and 1,4-hexadiene can be used as non-conjugated dienes, but ethylidene norbornene, which has high reactivity, is most preferably used.

[0028] Among the above constituent components, at least a portion of the ethylene and propylene are bioethylene and biopropylene, which are made from plant-derived bioethanol as the starting material. By using bioethylene and biopropylene as starting materials, the bio content (biomass content) of ethylene propylene rubber is improved. Considering environmental contributions, a bio content of 20% or more is preferable, and if cost is ignored, it is possible to increase it to 85-97%. In the future, as the use of bioethanol increases and costs decrease, the bio content can be increased. If the bio-content is 30%, it is possible to reduce carbon dioxide emissions by approximately 40% during the manufacturing process of the raw polymer. Using biomass EPDM (ethylene propylene diene terpolymer) with this high bio-content increases the bio-content of the entire rubber composition, making it even more preferable. The rubber composition used in the present invention is an unvulcanized rubber obtained by mixing the above-described raw material polymer with the various compounding ingredients shown below, which is heated in a mold so as to be integrated with a core bar, and then vulcanized and bonded to form a sealing ring (annular seal).

[0029] Using EPDM as an example, various compounding agents are shown below.

[0030] [Crosslinking agent used in EPDM] (1) Sulfur (2) Peroxides (dicumyl peroxide, etc.)

[0031] [Reinforcing material used in EPDM] (1) Carbon black (biomass carbon black)

[0032] [Antioxidants used in EPDM] (1) Substituted diphenylamines (2) N,N'-diphenyl-p-phenylenediamine (3) Polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (4) 4,4'-methylene-bis-(2,6-di-tert-butylphenol) [Vulcanization accelerators used in EPDM] (1) 2-Mercaptobenzothiazole (2) Dibenzothiazyl disulfide (3) Zinc salt of 2-mercaptobenzothiazole (4) Cyclohexylamine salt of 2-mercaptobenzothiazole (5) 2-(N,N'-Diethylthiocarbamoylthio)benzothiazole (6) 2-(4'-morpholinodithio)benzothiazole (7) N-Cyclohexyl-2-benzothiazyl sulfenamide (8) N,N-Dicyclohexyl-2-benzothiazyl sulfenamide (9) N-Oxydiethylene-2-benzothiazyl sulfenamide (10) N-tert-butyl-2-benzothiazyl sulfenamide (11) Diethyl thiourea (12) Dibutyl thiourea (13) Tetramethylthiuram monosulfide (14) Tetramethylthiuram disulfide (15) Tetraethylthiuram disulfide (16) Dipentamethylenethiuram tetra or hexasulfide (17) Tetrakis(2-ethylhexyl)thiuram disulfide (18) Zinc dimethyl dithiocarbamate (19) Zinc diethyl dithiocarbamate (20) Zinc di-n-butyl dithiocarbamate (21) Zinc ethylphenyl dithiocarbamate (22) Tellurium Diethyl Dithiocarbamate (23) Copper dimethyl dithiocarbamate (24) Iron dimethyl dithiocarbamate (25)Pentamethylenedithiocarbamic acid piperidine

[0033] [Vulcanization accelerators used in EPDM] (1) Complex activated zinc oxide (2) Stearic acid [Rubber softener used in EPDM] (1) Paraffin-based process oil

[0034] Furthermore, the rubber composition forming the seal member 13 of the rubber seal device 9 uses biomass carbon black made from vegetable oil as a filler (reinforcing agent), which improves the bio-content of the rubber composition compared to conventional products that use carbon black derived from coal or petroleum, making it environmentally friendly and contributing to carbon neutrality. As a result, rolling devices equipped with this rubber seal device are also environmentally friendly. Furthermore, when biomass EPDM is used in rubber compositions, the bio-content of the entire rubber composition can be further improved because bio-polyethylene and bio-polypropylene are used as raw materials. Second Embodiment

[0035] FIG. 2 shows an embodiment of a linear guide device, which is an embodiment of the rolling device of the present invention. The linear guide device described in this embodiment is merely an example, and the linear guide device is not limited to any particular configuration as long as it is provided with a grease composition in the internal space B of the linear guide device, which is a characteristic configuration of the present invention. The grease composition and rubber composition of the linear guide device are described in the first embodiment, and will not be described here.

[0036] In the linear guide device of this embodiment, a slider 15 having a substantially U-shaped cross section is mounted on a rectangular guide rail 21 so as to be relatively movable in the axial direction. The slider 15 is composed of a slider body 15a and end caps 15b detachably attached to both axial ends of the slider body 15a. One rolling element rolling groove 17, which is a recessed groove having a cross section shaped like a quarter of a circle, is formed in the axial direction at the ridge where the top surface 21a and both side surfaces 21b of the guide rail 21 intersect, and the other rolling element rolling groove 18, which has a cross section shaped like a semicircle, is formed in the axial direction at the midpoint between both side surfaces 21b of the guide rail 21.

[0037] At the inner corners of both sleeve portions 19 of the slider body 15a, a rolling element rolling groove (not shown) having an approximately semicircular cross section is formed, which faces one of the rolling element rolling grooves 17 of the guide rail 21, and at the center of the inner surface of both sleeve portions 19, a rolling element rolling groove (not shown) having an approximately semicircular cross section is formed, which faces the other of the rolling element rolling grooves 18 of the guide rail 21. A rolling element rolling path (not shown) is formed by the rolling element rolling grooves 17, 18 of the guide rail 21 and the two rolling element rolling grooves of both sleeve portions 19. These two rolling element rolling paths are linear and have a substantially circular cross section. Furthermore, the slider 15 is provided with two rolling element return paths (not shown) consisting of through holes with a circular cross section that penetrate in the axial direction at the top and bottom of the thick-walled portion of the sleeve portion 19 of the slider body 15a.

[0038] The end cap 15b has a curved path (not shown) that connects the rolling element rolling path with the rolling element return path parallel to it, and these rolling element rolling path, rolling element return path and curved paths at both ends form a circulation path for the rolling elements, and a large number of rolling elements (not shown), for example steel balls, are loaded into this circulation path so that they can roll freely.

[0039] The slider 15 attached to the guide rail 21 moves smoothly along the guide rail 21 via the rolling of the rolling elements in the rolling element rolling path, and during this movement, the rolling elements circulate endlessly while rolling in the circulation path within the slider 15.

[0040] An internal space B (not shown), which is a circulation path for the rolling elements, is filled with the grease composition of the present invention. "Third embodiment"

[0041] FIG. 3 shows an embodiment of a ball screw, which is an embodiment of a rolling device having an internal space filled with the grease composition of the present invention. The ball screw described in this embodiment is merely an example, and any other configuration may be provided as long as it is equipped with the grease composition, which is a characteristic feature of the present invention. The grease composition and rubber composition of this ball screw are described in the first embodiment, and will not be described here.

[0042] The ball screw includes a screw shaft 31 having a helical screw groove 31a with an arc-shaped cross section on its outer peripheral surface, a cylindrical nut 33 having a helical screw groove on its inner surface that faces the screw groove 31a of the screw shaft 31 and is screwed onto the screw shaft 31, and a large number of balls (not shown) that are loaded so as to roll freely in a helical ball rolling space with a nearly circular cross section formed by the screw groove 31a of the screw shaft 31 and the screw groove of the nut 33. A grease composition is used as a lubricant in the internal space C of the ball screw, which is this ball rolling space.

[0043] Cylindrical lubricant supply members 35, 35 made of a lubricant-containing polymer are fitted inside both axial ends of the nut 33, and the inner diameter surface of the lubricant supply member 35 contacts only the outer diameter surface of the screw shaft 31 and does not contact the thread groove 31a. The lubricant supply member 35 is composed of two semi-cylindrical members and has a thin groove on its outer circumference, where a garter spring 36 is disposed to press the lubricant supply member 35 radially toward the outer circumference of the screw shaft 31 with a constant pressure. Therefore, even if the inner circumference surface of the lubricant supply member 35 wears due to long-term operation, appropriate contact with the screw shaft 31 is always maintained, ensuring good lubrication.

[0044] Rubber seal devices 37, 37 are press-fitted onto the axial outside of the lubricant supply member 35, and when the nut 33 moves, the rubber seal device 37 slides against the screw shaft 31, reliably sealing the inside, preventing foreign matter such as water and dust from entering through the opening in the gap between the screw shaft 31 and the nut 33 and preventing the lubricant consisting of the grease composition from leaking out of the nut 32.

[0045] (Example of embodiment) It is preferable to prepare grease using vegetable oil-derived biomass carbon black as a thickener, rapeseed oil as the base oil, and naturally occurring vitamin E as an antioxidant. Specifically, it is preferable to use vegetable oil-derived biomass carbon black (100% bio-based) manufactured by Mitsubishi Chemical Corporation as a thickener. [Industrial Applicability]

[0046] The present invention can be applied to rolling devices in general. [Explanation of symbols]

[0047] 1. Inner circle 3 outer ring 5 rolling elements 7 Cage 9 Rubber seal device 11 Reinforcement member 13 Elastic member (sealing member) 15 Slider 17 Rolling element rolling groove 18 Rolling element rolling groove 19 Both sleeves 21 Guide rail 31 Screw shaft 33 Nut 35 Lubricant supply member 36 Garter Spring 37 Rubber seal device A, B, C interior space

Claims

1. A grease composition comprising at least a base oil and a thickener, wherein the base oil is a vegetable oil and the thickener is biomass carbon black.

2. 2. A rolling device according to claim 1, wherein the grease composition contains naturally occurring vitamin E as an antioxidant.

3. A rolling device, characterized in that the grease composition according to claim 1 or 2 is filled into an internal space thereof.

4. 4. The rolling device according to claim 3, wherein the rolling device is a rolling bearing.

5. 4. The rolling device according to claim 3, wherein the rolling device is a linear guide device.

6. 4. The rolling device according to claim 3, wherein the rolling device is a ball screw.

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