Wheel and method for manufacturing a wheel

Abstract

To provide a wheel with good durability and a method for manufacturing a wheel. [Solution] A wheel comprising a wheel portion and a tire portion attached to the outer circumference of the wheel portion, which conforms to the driving performance requirements based on the driving performance test of JIS B 8922:2015, except that the driving distance of the driving performance test conditions has been changed to 100 km, and the electrical resistance value in the electrical resistance test based on JIS B 8922:2015 is 1 × 10⁻¹⁰ 5 A wheel that is less than or equal to Ω.

Description

[Technical Field]

[0001] This disclosure relates to a wheel and a method for manufacturing a wheel. [Background technology]

[0002] Patent Document 1 discloses a conductive wheel for travel within a cleanroom. This wheel comprises a tire and a wheel. The tire is made of polyurethane elastomer compounded with a conductive material. The wheel is made of polyamide (nylon resin) compounded with a conductive material. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-119401 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Both polyurethane elastomers and polyamides are materials with very low surface free energy, and their adhesion is very poor. Therefore, in the wheel described in Patent Document 1, the adhesion between the tire and the wheel is weak. As a result, in the wheel described in Patent Document 1, the tire is prone to detaching from the wheel after prolonged use.

[0005] This disclosure is made in view of the above circumstances and aims to provide a wheel with good durability and a method for manufacturing a wheel. This disclosure can be implemented in the following forms. [Means for solving the problem]

[0006] The wheel section and A wheel comprising a tire portion attached to the outer circumference of the wheel portion, It conforms to the regulations on running performance based on the running performance test of JIS B 8922:2015, except that the running distance in the running performance test conditions is changed to 100 km. The electric resistance value in the electric resistance test based on JIS B 8922:2015 is 1 × 10 5 Ω or less, for the wheel.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a wheel with good durability and a method for manufacturing the wheel.

Brief Description of the Drawings

[0008] [Figure 1] It is a front view of the wheel of the first embodiment. [Figure 2] It is a side view of the wheel of FIG. 1. [Figure 3] It is a cross-sectional view showing a state where the mold 40 is arranged so as to cover the outer peripheral surface of the wheel portion in the wheel manufacturing process. [Figure 4] It is a cross-sectional view showing a state where the resin composition is injected into the mold and the tire portion is formed on the outer periphery of the wheel portion in the process following FIG. 3.

Modes for Carrying Out the Invention

[0009] Here, desirable examples of the present disclosure are shown. 〔1〕A wheel comprising a wheel portion and <…]] a tire portion attached to the outer periphery of the wheel portion, wherein it conforms to the regulations on running performance based on the running performance test of JIS B 8922:2015, except that the running distance in the running performance test conditions is changed to 100 km. The electric resistance value in the electric resistance test based on JIS B 8922:2015 is 1 × 10 5 Ω or less, for the wheel.

[0010] 〔2〕The wheel according to 〔1〕, wherein the outer peripheral surface of the wheel portion is subjected to plasma surface treatment.

[0011] [3] Wheel section and A wheel comprising a tire portion attached to the outer circumference of the wheel portion, The outer surface of the wheel portion is subjected to plasma surface treatment.

[0012] [4] The wheel according to any one of [1] to [3], wherein an adhesive layer is formed between the outer circumferential surface of the wheel portion and the inner circumferential surface of the tire portion.

[0013] [5] Wheel section and A method for manufacturing a wheel comprising a tire portion attached to the outer circumference of the wheel portion, A method for manufacturing a wheel, comprising: applying a plasma surface treatment to the outer surface of the wheel portion; arranging a mold so as to cover the outer surface of the wheel portion; injecting a resin composition into the mold; and forming the tire portion on the outer circumference of the wheel portion.

[0014] [6] The method for manufacturing a wheel according to [5], wherein an adhesive is applied to the outer circumferential surface of the surface-treated wheel portion, and then the resin composition is injected into the mold.

[0015] The disclosure is described in detail below. In this specification, when a numerical range is described using "-", it includes both the lower and upper limits unless otherwise specified. For example, the description "10-20" includes both the lower limit "10" and the upper limit "20". In other words, "10-20" has the same meaning as "10 or more and 20 or less". Furthermore, in this specification, the upper and lower limits of each numerical range can be combined in any way.

[0016] <First Embodiment> 1. Wheels 10 As shown in Figures 1 and 2, the wheel 10 of the first embodiment comprises a wheel portion 20 and a tire portion 30 attached to the outer circumference of the wheel portion 20. The wheel conforms to the driving performance requirements based on the driving performance test of JIS B 8922:2015, except that the driving distance of the driving performance test conditions was changed to 100 km, and the electrical resistance value in the electrical resistance test based on JIS B 8922:2015 is 1 × 10⁻¹⁰. 5 It is less than or equal to Ω.

[0017] As shown in Figures 1 and 2, the wheel portion 20 includes a hub portion 22 equipped with a bearing portion 21, a rim portion 23 formed on the outer circumference, and a plurality of spoke portions 24 connecting the hub portion 22 and the rim portion 23. However, the wheel portion 20 may also be configured without spoke portions 24.

[0018] 1-1. Wheel section 20 The wheel portion 20 preferably includes a resin material and a conductive material. Examples of the resin material include polyamide and ABS.

[0019] 1-1-1. Polyamide Examples of polyamides include polyamides obtained by polycondensation of aliphatic, alicyclic, or aromatic diamines such as hexamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(p-aminocyclohexylmethane), m-xylylenediamine, and p-xylylenediamine with aliphatic, alicyclic, or aromatic dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid; polyamides obtained by condensation of aminocarboxylic acids such as ε-aminocaproic acid and 11-aminoundecanoic acid; polyamides obtained from lactams such as ε-caprolactam and ω-laurolactam; copolymerized polyamides consisting of these components; and mixtures of these polyamides.

[0020] It is preferable to use a polyamide containing an aliphatic skeleton (a skeleton other than an aromatic ring, including a chain-like or branched hydrocarbon group or an alicyclic structure), and it is more preferable to use a polyamide composed solely of an aliphatic skeleton. Examples of polyamides composed solely of an aliphatic skeleton include polyamide 6, polyamide 66, polyamide 610, polyamide 9, polyamide 11, polyamide 12, polyamide 6 / 66, polyamide 66 / 610, and polyamide 6 / 11.

[0021] 1-1-2. ABS ABS is a resin containing three components: acrylonitrile, butadiene, and styrene. ABS may be a copolymer, a graft copolymer, or a polymer blend of these. There are no particular restrictions on the method of producing ABS; for example, it may be produced by continuous bulk polymerization, emulsion polymerization, solution polymerization, or suspension polymerization.

[0022] 1-1-3. Conductive materials Examples of conductive materials include carbon fibers and conductive carbon. Examples of conductive carbon include conductive carbon blacks such as acetylene black, furnace black, and Ketjenblack (registered trademark).

[0023] The volume resistivity of the raw materials, including resin materials and conductive materials, according to IEC62631, is 10 from the viewpoint of improving the conductivity of the wheel portion 20. 5 Preferably Ω·m or less, 10 4 A value of Ω·m or less is preferable. The lower limit is not particularly limited, but for example, 10 2 It is Ω·m.

[0024] 1-1-4. Raw materials containing polyamides and conductive materials Commercially available raw materials containing polyamide and conductive materials include, for example, Unitika's "RUN" series (e.g., 6 Nylon RUN10C-SC, with a volume resistivity of 10 as specified in IEC62631). 2 Ω·m) etc. can be used.

[0025] 1-1-5. Raw materials containing ABS and conductive materials As commercially available products of raw materials containing ABS and conductive materials, for example, the "EK" series manufactured by Techno UMG (e.g., ABS Excelloy EK13C8, with a volume resistivity of 10 4 Ω·m as defined in IEC62631) etc. can be used.

[0026] 1-1-6. Physical properties of the wheel part 20 From the perspective of enhancing the conductivity of the wheel 10, the volume resistivity of the wheel part 20 based on IEC62631 is preferably 10 4 Ω·m or less, more preferably 10 3 Ω·m or less, and even more preferably 10 2 Ω·m or less.

[0027] 1-2. Tire part 30 The tire part 30 preferably contains an elastomer and a conductive material.

[0028] 1-2-1. Elastomer As the elastomer, for example, various thermoplastic elastomers such as polyurethane-based, polyolefin-based, polyester-based, and polyamide-based, and thermosetting elastomers such as natural rubber and synthetic rubber can be used. Among these, polyurethane-based thermoplastic elastomers (thermoplastic polyurethane: TPU) and polyolefin-based thermoplastic elastomers (e.g., Santoprene as a commercially available product) are preferred. From the perspective of excellent wear resistance, polyurethane-based thermoplastic elastomers are more preferred.

[0029] Thermoplastic polyurethane (TPU) is preferably composed of a soft segment formed from a polyol and a hard segment formed from a urethane group (urethane bond). For example, an adipate-type polyester polyol having hydroxyl groups at both ends by condensation of 1,4-butanediol and adipic acid, and a thermoplastic polyurethane produced by a polyaddition reaction (urethane formation reaction) with hexamethylene diisocyanate (HDI) which is a polyisocyanate, etc. can be mentioned.

[0030] Examples of polyols used include polycarbonate polyols, condensation-polymerized polyester polyols, polyester polyols obtained by ring-opening polymerization of cyclic esters such as ε-caprolactone, polyether polyols obtained by ring-opening polymerization of cyclic ethers, and polyether ester polyols obtained by copolymerization thereof. These polyols can also be used in combination with 1,4-butanediol and the like.

[0031] Examples of polyisocyanates used include hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI), hydrogenated MDI, and isophorone diisocyanate (IPDI). Among these polyisocyanates, HDI, MDI, and hydrogenated MDI, which have symmetrical molecular structures, are preferred. Furthermore, by using isocyanate-terminated prepolymers having isocyanate groups at both ends, the hydrogen bonding strength of the hard segments can be increased, or the crystalline phase can be grown.

[0032] In addition to the polyols and polyisocyanates mentioned above, other additives can be incorporated as raw materials for thermoplastic polyurethane. Examples of such additives include inorganic fillers such as talc, silica, and calcium carbonate. By incorporating inorganic fillers, the rigidity of the elastomer can be increased, and the pulverability when powdered can be improved. Other additives that can be incorporated include resins or rubbers. Examples of resins include polyolefin resins such as polyethylene and polypropylene. Examples of rubbers include ethylene-α-olefin copolymer rubber and styrene-ethylene-butylene-styrene copolymer rubber (SEBS).

[0033] As the polyolefin-based thermoplastic elastomer, commercially available elastomers having a sea-island structure, such as Santoprene, can be used. This elastomer contains a polymer that forms the sea phase and a polymer that forms the island phase. The polymer that forms the island phase is not particularly limited, but elastomers are preferred, for example. Here, the elastomer may be natural rubber, or synthetic rubber such as ethylene / propylene rubber (EPR), ethylene / propylene / diene monomer rubber (EPDM), styrene block copolymer rubber (including SEBS, SI, SIS, SB, SBS, SIBS, etc., where S is styrene, EB is random ethylene + butene, I is isobutylene, and B is butadiene), butyl rubber, halobutyl rubber, isobutylene / para-alkylstyrene copolymer, isobutylene / para-alkylstyrene copolymer, isobutylene / para-alkylstyrene halogenated copolymer, polyisobutylene, acrylonitrile / butadiene copolymer, polychloroprene, alkyl acrylate rubber, chlorinated isobutylene rubber, acrylonitrile chloride isobutylene rubber, polybutadiene rubber, etc. Among these, it is preferable to use an elastomer containing an ethylene / α-olefin / diene monomer polymer such as ethylene / propylene / diene monomer rubber (EPDM).

[0034] In ethylene / α-olefin / diene polymers, the diene monomer used is preferably a conjugated (or unconjugated) diene having 30 or fewer carbon atoms (preferably 20 or fewer). Examples of dienes include 5-ethylidene-2-norbornene (ENB), 1,4-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, vinylnorbornene, dicyclopentadiene, and combinations of two or more of these.

[0035] In ethylene / α-olefin / diene polymers, it is preferable to use α-olefins with an integer number of carbon atoms between 3 and 8. Among these, propylene is particularly preferred.

[0036] Next, the elastomer used as the island phase is preferably cured or crosslinked. By curing or crosslinking in this way, it becomes easier to manufacture the wheel 10 of this disclosure. In particular, it is preferable to use a dynamically crosslinked ethylene / α-olefin / diene polymer. "Dynamically crosslinked" means that the polymer is crosslinked under high shear conditions, such as when it is melt-kneaded. As the crosslinking agent used here, known crosslinking agents can be used, but for example, sulfur, peroxides, etc., can be used. In addition to the crosslinking agent, polymers such as oxime nitroso compounds, dimethacrylate-based, triester-based or triallyl isocyanurate-based monomers, and polybutadiene may be used when crosslinking. Furthermore, known crosslinking accelerators may be added.

[0037] The polymer used to form the sea phase is the same as the polymer used to form the island phase, and is not particularly limited, but it is preferably a thermoplastic resin such as a polyolefin resin obtained by polymerizing an olefin having an integer number of carbon atoms between 2 and 10. Examples of olefins include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, and 1-decene.

[0038] 1-2-2. Conductive materials Examples of conductive materials include carbon fibers and conductive carbon. Examples of conductive carbon include conductive carbon blacks such as acetylene black, furnace black, and Ketjenblack (registered trademark).

[0039] 1-2-3. Raw materials containing elastomers and conductive materials As for commercially available elastomers, for example, the "Elastran ET" series from BASF Japan (e.g., Elastran ET1090-10) can be used. As for commercially available conductive materials, for example, "Denka Black" from Denka Co., Ltd. can be used. The mass ratio of elastomer to conductive material is preferably 70:30-80:20, for example, 75:25.

[0040] 1-2-4. Physical properties of the tire section 30 The volume resistivity of the tire portion 30 is set such that 10 improves the conductivity of the wheel 10. 4 Preferably less than Ω·cm, 10 3 Ω·cm or less is more preferable, 10 2 A value of Ω·cm or less is even more preferable. The lower limit of the above volume resistivity is, for example, 10 Ω·cm. Here, the volume resistivity of the tire portion 30 was calculated using the Wheatstone bridge method with a digital multimeter after melting the raw materials containing elastomer and conductive material at 200°C to create a 3 cm wide belt-shaped test piece. The calculation formula is: Volume resistivity = (Measured resistance value × Test piece thickness × Test piece width) / Distance between electrodes.

[0041] The surface resistance value of the tire portion 30 is set such that 10 improves the conductivity of the wheel 10. 5 Preferably less than Ω, 10 4 Ω or less is more preferable, 10 3 A value of Ω or less is even more preferable. The lower limit of the above surface resistance value is, for example, 10 2 The value is Ω. The surface resistance is the average value of measurements taken at three points on a 3 cm wide belt-shaped test piece prepared by melting raw materials containing elastomer and conductive material at 200°C using a tester.

[0042] 1-3. Plasma surface treatment of wheel section 20 Preferably, the outer surface of the wheel portion 20 is subjected to plasma surface treatment. Plasma surface treatment activates the outer surface of the wheel portion 20, improving its adhesion to the tire portion 30.

[0043] It is preferable that the plasma surface treatment of the outer circumferential surface of the wheel portion 20 introduces active groups that interact with the functional groups of the tire portion 30. For example, examples of active groups introduced by plasma surface treatment include oxidizing groups such as peroxyl radicals (-OO·), hydroperoxide groups (-O-OH), carbonyl groups (-C(=O)-), aldehyde groups (-C(=O)-H), carboxyl groups (-C(=O)-OH), and hydroxyl groups (-OH). Among these, it is more preferable to introduce at least one selected from peroxyl radicals (-OO·), hydroperoxide groups (-O-OH), carbonyl groups (-C(=O)-), aldehyde groups (-C(=O)-H), carboxyl groups (-C(=O)-OH), and hydroxyl groups (-OH) from the viewpoint of improving adhesion.

[0044] 1-4.Adhesive layer Preferably, an adhesive layer is formed between the outer circumferential surface of the wheel portion 20 and the inner circumferential surface of the tire portion 30. The adhesive layer is formed by applying adhesive to the plasma-surface-treated portion of the wheel portion 20, and then removing the solvent in the adhesive component by natural drying. The presence of an adhesive layer on the plasma-surface-treated portion of the wheel portion 20 prevents hands or other objects from touching the activated portion by plasma irradiation before it acts on the functional groups of the tire portion 30. Therefore, poor adhesion between the outer circumferential surface of the wheel portion 20 and the inner circumferential surface of the tire portion 30 can be prevented. In addition, the plasma surface treatment of the wheel portion 20 is expected to strengthen the interaction between the wheel portion 20 and the adhesive layer.

[0045] As for the adhesive, one that is compatible with bonding to the tire portion 30 is preferred. Examples of adhesives include epoxy resin-containing adhesives and urethane-based adhesives. A commercially available epoxy resin-containing adhesive is, for example, Chemlock 210 manufactured by Road Japan Inc. (viscosity of 300 mPa·s at 25°C with a Brookfield LVT viscometer at spindle 2, 30 rpm). A commercially available urethane-based adhesive is, for example, Silbond 48 manufactured by Sekisui Fuller Co., Ltd. (viscosity index of 15 seconds at 25°C with Zahn cup No. 3).

[0046] 1-5. Physical properties of wheel 10 1-5-1. Driving Performance Wheel 10 conforms to the running performance requirements based on the running performance test of JIS B 8922:2015, except that the running distance in the running performance test conditions has been changed to 100 km. In the running performance test, the outer surface of wheel 10 is brought into contact with the outer surface of a steel drum with protrusions, a load is applied to the wheel portion 20 toward the steel drum, and wheel 10 is rotated. The running performance requirements are met if the following conditions (a) and (b) are met. (a) No cracks or peeling occur in the wheel body, interface, or tire. (b) The permanent deformation of the wheel outer diameter is 2% or less.

[0047] Wheel 10 conforms to the above-mentioned driving performance specifications when its outer diameter is 130 mm, its load capacity is 200 kg, its rotational speed is 4 km / h, and its driving distance is 20 km or 100 km.

[0048] 1-5-2. Electrical Resistance Value The electrical resistance value of wheel 10 in the electrical resistance test based on JIS B 8922:2015 is 1 × 10⁻¹⁰, from the perspective of improving the conductivity of wheel 10. 5 It is less than or equal to Ω, and 1 × 10 4 Preferably less than Ω, 1 × 10 3 A value of Ω or less is preferable.

[0049] 1-5-3. Load-bearing capacity In the load-bearing performance test of wheel 10, the change in the outer diameter of the wheel is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less, from the viewpoint of improving the durability of wheel 10. Here, the change in the outer diameter of the wheel was measured in accordance with the load-bearing performance test provisions of JIS B 8922:2015, except that the additional load specified in JIS B 8922:2015 was changed to three times, and the period for applying the additional load was changed to one week.

[0050] 1-6. Manufacturing method of wheel 10 The manufacturing method for the wheel 10 involves first applying a plasma surface treatment to the outer circumferential surface of the wheel portion 20, then positioning a mold 40 (see Figures 3 and 4) so ​​as to cover (surround) the outer circumferential surface of the wheel portion 20, and injecting a resin composition (raw materials including elastomer and conductive material) into the mold 40 to form the tire portion 30 on the outer circumferential surface of the wheel portion 20. In the manufacturing method for the wheel 10, it is preferable to apply an adhesive to the surface-treated outer circumferential surface of the wheel portion 20 before injecting the resin composition into the mold 40.

[0051] Specifically, the method for manufacturing the wheel 10 includes a process for manufacturing the wheel portion 20, a process for plasma surface treatment of the wheel portion 20, a process for forming an adhesive layer, and a process for molding the tire portion 30.

[0052] In the manufacturing process of the wheel portion 20, the wheel portion 20 is formed by injecting raw materials, such as resin material (polyamide, ABS, etc.) and conductive material (conductive carbon, etc.), into a mold. The temperature of the cylinder is, for example, 210°C-275°C. The temperature of the mold is, for example, 60°C.

[0053] In the plasma surface treatment process for the wheel portion 20, plasma is irradiated onto the outer surface of the wheel portion 20 using a plasma irradiation device. The method of plasma surface treatment is described below. There are no particular restrictions on the conditions for applying plasma surface treatment to the outer surface of the wheel portion 20, as long as the surface after treatment is activated, and it can be carried out by known methods. In other words, conditions that enable the generation of plasma can be appropriately adopted.

[0054] The temperature of the environment during plasma processing (i.e., the environment in which the wheel portion 20 is installed and plasma is generated) is preferably 0°C to 240°C, more preferably 10°C to 220°C, and even more preferably 15°C to 200°C, from the viewpoint of improving adhesion and simplifying plasma processing.

[0055] The atmospheric pressure in the plasma treatment environment is preferably 5 hPa to 2000 hPa, more preferably 10 hPa to 1500 hPa, and even more preferably 10 hPa to 1300 hPa, from the viewpoint of improving adhesion and simplifying the plasma treatment. For plasma generation, it is preferable to use a high-frequency power supply with an applied voltage frequency of 50 Hz to 2.45 GHz.

[0056] As gases used to generate plasma, for example, noble gases such as helium, argon, and neon, and reactive gases such as air, oxygen, nitrogen, hydrogen, and ammonia can be used. These gases may consist of only one or more noble gases, only one or more reactive gases, or a mixture of one or more noble gases and an appropriate amount of one or more reactive gases. Plasma generation may be carried out under conditions where the gas atmosphere is controlled using a chamber, or it may be carried out under completely open atmospheric conditions, for example, by flowing the gas onto the electrode.

[0057] For example, the wheel portion 20 is rotated around its axis while plasma is irradiated onto its outer surface. If the plasma irradiation width (e.g., 8 mm) is smaller than the rim width of the wheel portion 20 (e.g., 38 mm), a horizontal slider is attached to the head of the plasma irradiation device, and the plasma is irradiated onto the outer surface while sliding it laterally along the outer surface at a predetermined speed (e.g., 3 mm / sec). From the viewpoint of preventing the plasma irradiation time from becoming too long at specific points on the wheel portion 20, it is preferable to rotate the wheel portion 20 around its axis and move the head of the plasma irradiation device.

[0058] In the adhesive layer formation process, the adhesive is applied to the plasma-treated portion of the wheel portion 20 using a brush or the like, and then the solvent in the adhesive component is removed by natural drying. The adhesive may be heat-cured as needed.

[0059] In the molding process for the tire portion 30, as shown in Figure 3, a mold 40 (covering mold) is positioned to cover the outer circumferential surface of the wheel portion 20. The mold 40 is configured to be, for example, divided into two parts, comprising a first mold portion 41 and a second mold portion 42. The first mold portion 41 and the second mold portion 42 are assembled to sandwich the wheel portion 20 from the axial direction. Subsequently, as shown in Figure 4, a resin composition is injected (inserted) into the mold 40 to mold the tire portion 30 onto the outer circumference of the wheel portion 20. For example, the resin composition is melted at a high temperature (e.g., 230°C) in a cylinder, injected around the wheel portion 20 using a single gate, and then demolded to obtain the wheel 10. Note that a multi-point gate may be used in injection molding. The mold temperature is, for example, 60°C.

[0060] 1-7. Application Examples of Wheel 10 The wheel 10 can be used, for example, as the wheel of a trolley or AGV (Automated Guided Vehicle) that travels in a cleanroom, or as a wheel for transporting and moving equipment installed on manufacturing equipment or evaluation equipment used in a cleanroom.

[0061] 1-8. Effects of the First Embodiment We can provide a wheel 10 that can withstand running performance tests (shear and drop tests) that meet the JIS standard (JIS B 8922:2015), and can even withstand conditions more severe than those specified in this standard. This provides a conductive wheel 10 that is less prone to generating static electricity. By plasma-treating the outer surface of the wheel portion 20 to impart surface activity, and then covering and molding the tire portion 30, the adhesion strength at the interface between the wheel portion 20, which contains polyamide or ABS, and the tire portion 30, which contains elastomer, can be improved.

[0062] For example, because the wheels 10 have excellent wear resistance, when a trolley or AGV used to transport parts in a cleanroom where semiconductors are manufactured travels over a grating installed on the floor, the wheels can be worn down by the steps of the grating, generating wear particles that could adhere to the transported parts and result in defective products. For example, since the wheel 10 comprises a wheel portion 20 containing polyamide or ABS and a tire portion 30 containing elastomer, it is possible to prevent the impact on the wheel 10 from the grating surface from being transmitted to the trolley or AGV, prevent the transported parts from vibrating and generating static electricity on the parts, and prevent the parts from being damaged by impact. For example, it is possible to prevent the wheels 10 from becoming electrically charged while driving or waiting, and to prevent dust from the air from adhering to the wheels 10.

[0063] <Second Embodiment> 1. Wheels 10 The wheel 10 of the second embodiment, like the wheel 10 of the first embodiment, comprises a wheel portion 20 and a tire portion 30 attached to the outer circumference of the wheel portion 20, as shown in Figures 1 and 2. The outer surface of the wheel portion 20 is subjected to plasma surface treatment.

[0064] As shown in Figure 1, the wheel portion 20 includes a hub portion 22 equipped with a bearing portion 21, a rim portion 23 formed on the outer circumference, and a plurality of spoke portions 24 connecting the hub portion 22 and the rim portion 23. However, the wheel portion 20 may also be configured without the spoke portions 24.

[0065] Regarding the configuration of the wheel 10, the descriptions in the sections "1-1. Wheel section 20", "1-2. Tire section 30", and "1-4. Adhesive layer" of the first embodiment will be applied as is, and the description will be omitted.

[0066] 1-2. Plasma surface treatment of wheel section 20 The outer surface of the wheel portion 20 is activated by plasma surface treatment, improving its adhesion to the tire portion 30.

[0067] It is preferable that the plasma surface treatment of the outer circumferential surface of the wheel portion 20 introduces active groups that interact with the functional groups of the tire portion 30. For example, examples of active groups introduced by plasma surface treatment include oxidizing groups such as peroxyl radicals (-OO·), hydroperoxide groups (-O-OH), carbonyl groups (-C(=O)-), aldehyde groups (-C(=O)-H), carboxyl groups (-C(=O)-OH), and hydroxyl groups (-OH). Among these, it is more preferable to introduce at least one selected from peroxyl radicals (-OO·), hydroperoxide groups (-O-OH), carbonyl groups (-C(=O)-), aldehyde groups (-C(=O)-H), carboxyl groups (-C(=O)-OH), and hydroxyl groups (-OH) from the viewpoint of improving adhesion.

[0068] 1-3. Physical properties of wheel 10 1-3-1. Driving Performance Wheel 10 should preferably conform to the running performance requirements based on the running performance test of JIS B 8922:2015, except that the running distance in the running performance test conditions has been changed to 100 km. In the running performance test, the outer surface of wheel 10 is brought into contact with the outer surface of a steel drum with protrusions, a load is applied to the wheel portion 20 toward the steel drum, and wheel 10 is rotated. The running performance requirements are met if the following provisions (a) and (b) are met. (a) No cracks or peeling occur in the wheel body, interface, or tire. (b) The permanent deformation of the wheel outer diameter is 2% or less.

[0069] Wheel 10 conforms to the above-mentioned driving performance specifications when its outer diameter is 130 mm, its load capacity is 200 kg, its rotational speed is 4 km / h, and its driving distance is 20 km or 100 km.

[0070] 1-3-2. Electrical Resistance Value The electrical resistance value of wheel 10 in the electrical resistance test based on JIS B 8922:2015 is 1 × 10⁻¹⁰, from the perspective of improving the conductivity of wheel 10. 5 Preferably less than Ω, 1 × 10 4 It is more preferable to have an Ω or less, and 1 × 103 A value of Ω or less is even more preferable.

[0071] 1-3-3. Load-bearing capacity In the load-bearing performance test of wheel 10, the change in the outer diameter of the wheel is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less, from the viewpoint of improving the durability of wheel 10. Here, the change in the outer diameter of the wheel was measured in accordance with the load-bearing performance test provisions of JIS B 8922:2015, except that the additional load specified in JIS B 8922:2015 was changed to three times, and the period for applying the additional load was changed to one week.

[0072] 1-4. Manufacturing method of wheel 10 The method for manufacturing the wheel 10 is described in the section "1-6. Method for manufacturing the wheel 10" of the first embodiment, and that description is omitted here.

[0073] 1-5. Application Examples of Wheel 10 Regarding the application examples of wheel 10, the explanation in section "1-7. Application Examples of Wheel 10" of the first embodiment will be applied as is, and the description will be omitted.

[0074] 1-6. Effects of the Second Embodiment The wheel 10 of the second embodiment provides the same effects as the wheel 10 of the first embodiment. [Examples]

[0075] 1. Wheel manufacturing Wheels for Example 1-4 and Comparative Example 1-3 were fabricated using the configurations shown in Table 1, and their physical properties were evaluated. The configurations and physical properties of the tire and wheel portions of the wheels for Example 1-4 and Comparative Example 1-3 are shown in Table 1. The wheels for Example 1-4 and Comparative Example 1-3 were solid wheels with an outer diameter of 130 mm and a rim width of 38 mm.

[0076] [Table 1]

[0077] • Example 1 A wheel was manufactured using the same method as the "Method for Manufacturing Wheel 10" in the first embodiment described above. As the raw material for the wheel part, conductive nylon (conductive polyamide) 6 Nylon RUN10C-SC manufactured by Unitika Corporation (with a volume resistivity of 10 as specified in IEC62631) was used. 2 The Ω·m ratio was used. The wheel portion was injection molded under the conditions of a cylinder temperature of 275°C and a mold temperature of 60°C.

[0078] Plasma surface treatment of the wheel section was performed using a high-frequency atmospheric pressure plasma irradiation device (PHW-1000, manufactured by Wedge Co., Ltd.). With an output voltage of 0.9kV, a workpiece distance of 11mm, and an air supply pressure of 0.125MPa, the resin wheel was rotated at 20m / min while plasma was irradiated onto the outer surface of the wheel section. The plasma irradiation width was approximately 8mm, and a horizontally moving slider was attached to the head of the plasma irradiation device, allowing the device to slide laterally along the outer surface of the wheel section at a speed of 3mm / sec while irradiating the circumferential surface with plasma.

[0079] As adhesive 1, Chemlock 210, manufactured by Road Japan Inc., an epoxy resin-containing adhesive (viscosity of 300 mPa·s measured using a Brookfield LVT viscometer at spindle 2, 30 rpm, and 25°C), was used. After applying adhesive 1 to the plasma-irradiated area of ​​the wheel with a brush, the solvent in the adhesive components was removed by natural drying.

[0080] Conductive polyurethane elastomer (TPU) was used as the raw material for the tire portion. The conductive polyurethane elastomer used was a mixture of thermoplastic polyurethane (Elastran ET1090-10 from BASF Japan) and carbon black (Denka Black from Denka Co., Ltd.) in a weight ratio of 75:25. The wheel portion was inserted into a covering mold for molding the tire portion, and the conductive polyurethane elastomer, melted at a cylinder temperature of 230°C, was injection molded around the wheel portion using a single gate. The wheel was then demolded to obtain the wheel. The mold temperature was set to 60°C.

[0081] • Example 2 The wheel was manufactured in the same manner as in Example 1, except that adhesive 2 (urethane-based adhesive, Silbond 48 manufactured by Sekisui Fuller Co., Ltd.) was used instead of adhesive 1 as the adhesive applied to the plasma-irradiated portion of the wheel.

[0082] • Example 3 The wheel was manufactured in the same manner as in Example 1, except that no adhesive was applied to the plasma-irradiated portion of the wheel.

[0083] • Example 4 The wheel was manufactured in the same manner as in Example 3, except that conductive ABS resin was used instead of conductive nylon as the raw material for the wheel. The conductive ABS resin used was Exeloy EK13C8 (with a volume resistivity of 10 as specified in IEC62631) manufactured by Techno UMG. 4 The Ω·m ratio was used. The wheel portion was injection molded under the conditions of a cylinder temperature of 210°C and a mold temperature of 60°C.

[0084] • Comparative Example 1 The wheel was manufactured in the same manner as in Example 4, except that plasma surface treatment was not applied to the outer circumferential surface of the wheel portion.

[0085] • Comparative Example 2 The wheel was manufactured in the same manner as in Comparative Example 1, except that conductive nylon was used instead of conductive ABS resin as the raw material for the wheel. The conductive nylon used was Unitika's 6 Nylon RUN10C-SC (with a volume resistivity of 10 as specified in IEC62631). 2 The Ω·m ratio was used. The wheel portion was injection molded under the conditions of a cylinder temperature of 275°C and a mold temperature of 60°C.

[0086] • Comparative Example 3 The wheel was manufactured in the same manner as in Example 1, except that plasma surface treatment was not applied to the outer circumferential surface of the wheel portion.

[0087] 2. Evaluation of the wheels 2-1. Driving performance The running performance was evaluated based on the running performance test specified in JIS B 8922:2015. The running performance test was conducted using the running test machine described in JIS B 8922:2015, with continuous running at a distance of 20 km or 100 km (set distance), a load of 200 kg, and a speed of 4 km / h. The outer surface of the wheel was in contact with the outer surface of a steel drum with protrusions, and a load was applied to the wheel portion toward the steel drum, causing the wheel to rotate. In Table 1, A and B in the running test column are as follows. A: After completing the set distance, there are no external abnormalities (no cracks or peeling in the wheel body, interface, and tire), and the permanent deformation of the wheel outer diameter is 2% or less. B: After completing the set distance, there are external abnormalities (cracks or peeling in the wheel body, interface, and tire), or the permanent deformation of the wheel outer diameter is greater than 2%. In addition, the "*" in Table 1 indicates that the interface between the wheel and tire parts separated due to shear stress, and the wear particles generated by the friction between the separated wheel and tire surfaces caused the surface to rise, resulting in an abnormal appearance.

[0088] 2-2. Electrical Characteristics The electrical characteristics of the wheel were measured based on JIS B 8922:2015, specifically the electrical resistance. An Advantest high-resistance meter (model number: R8340A) was used for the measurement. In Table 1, A and B in the electrical characteristics column are as follows: A: Electrical resistance value is 1.0 × 10 4 Ω or less B: Electrical resistance value is 1.0 × 10 4 Larger than Ω, 1.0 × 10⁻⁶ 5 Ω or less

[0089] 2-3. Load-bearing capacity The load-bearing capacity of the wheel was evaluated based on a load-bearing capacity test according to JIS B8922:2015. The evaluation equipment used was the Autograph AG-X manufactured by Shimadzu Corporation. The Autograph's compressor was brought into contact with the wheel, and the position where the load cell read 5N was set as the zero point. A load three times the load used in the running test (200kg) (600kg) was applied to the wheel and left undisturbed for one week. After 10 minutes had passed since the load was released, the crosshead was lowered again, and the amount of wheel deformation was checked from the position where the load on the load cell became 5N. In Table 1, A and B in the load-bearing capacity test column are as follows. A: Dimensional change is within 0.5% (±0.65 mm) of the dimension before testing (130 mm). B: Dimensional change is 0.5% or more (within ±0.65 mm) and within 1.5% (within ±1.95 mm) of the dimension before testing (130 mm).

[0090] 3. Evaluation Results As shown in Table 1, all of Examples 1-4 received an "A" rating for driving performance (20km, 100km). All of Comparative Examples 1-3 received a "B" rating for driving performance (20km, 100km). In Example 1-4, the outer circumferential surface of the wheel portion was plasma-surface-treated, and then the tire portion was molded onto the outer circumferential surface of the wheel portion. In Comparative Example 1-3, the outer circumferential surface of the wheel portion was not plasma-surface-treated, and the tire portion was molded onto the outer circumferential surface of the wheel portion. Therefore, by applying plasma surface treatment to the outer circumferential surface of the wheel portion, the adhesion strength at the interface between the wheel portion containing polyamide or ABS and the tire portion containing elastomer can be improved, and compliance with the driving performance requirements of JIS B 8922:2015 can be achieved.

[0091] As shown in Table 1, Example 1 received an "A" rating for driving performance (20km, 100km). Comparative Example 3 received a "B" rating for driving performance (20km, 100km). In Example 1, after plasma surface treatment was applied to the outer circumferential surface of the wheel portion, an adhesive layer was formed between the outer circumferential surface of the wheel portion and the inner circumferential surface of the tire portion. In Comparative Example 3, plasma surface treatment was not applied to the outer circumferential surface of the wheel portion, and an adhesive layer was formed between the outer circumferential surface of the wheel portion and the inner circumferential surface of the tire portion. Therefore, it is conceivable that plasma surface treatment of the wheel portion has the effect of strengthening the interaction between the wheel portion and the adhesive layer.

[0092] As shown in Table 1, all of Examples 1-4 received an "A" rating for their running performance (20km and 100km). Example 1-3 uses conductive nylon as the raw material for the wheel. Example 4 uses conductive ABS as the raw material for the wheel. Therefore, regardless of whether conductive nylon or conductive ABS is used as the raw material for the wheel, the adhesion strength at the interface with the tire part containing the elastomer can be improved, and a wheel can be realized that conforms to the running performance requirements of JIS B 8922:2015 (running distance: 20km) and can withstand even more severe conditions than this standard (running distance: 100km).

[0093] As shown in Table 1, all three examples (1-3) received an "A" rating for their running performance (20km and 100km). Examples 1 and 2 both have an adhesive layer formed between the outer circumferential surface of the wheel and the inner circumferential surface of the tire. Example 3 does not have an adhesive layer formed between the outer circumferential surface of the wheel and the inner circumferential surface of the tire. Therefore, regardless of the presence or absence of an adhesive layer between the outer circumferential surface of the wheel and the inner circumferential surface of the tire, the adhesion strength at the interface with the tire containing the elastomer can be improved, and a wheel can be realized that conforms to the running performance requirements of JIS B 8922:2015 (running distance: 20km) and can withstand even more severe conditions than this standard (running distance: 100km). In addition, Example 1 uses an adhesive containing epoxy resin, while Example 2 uses a urethane-based adhesive. Therefore, regardless of the type of adhesive, the adhesion strength at the interface with the tire portion containing the elastomer can be improved, allowing the wheel to meet the running performance requirements of JIS B 8922:2015 (running distance: 20km), and furthermore, to withstand even more severe conditions than this standard (running distance: 100km).

[0094] 4. Effects of the Examples According to this embodiment, a wheel with good durability can be obtained.

[0095] This disclosure is not limited to the embodiments detailed above, and various modifications or changes are possible within the scope of this disclosure. [Explanation of Symbols]

[0096] 10: Wheels 20: Wheel section 21: Bearing section 22: Hub section 23: Rim section 24: Spoke section 30: Tire Section 40: Mold 41: 1st mold part 42: 2nd mold part

Claims

1. The wheel section and A wheel comprising a tire portion attached to the outer circumference of the wheel portion, Except for changing the driving distance in the driving performance test conditions to 100 km, the vehicle conforms to the driving performance specifications based on the driving performance test of JIS B 8922:2015. The electrical resistance value in the electrical resistance test according to JIS B 8922:2015 is 1 × 10⁻⁶. ５ A wheel that is less than or equal to Ω.

2. The wheel according to claim 1, wherein the outer surface of the wheel portion is subjected to plasma surface treatment.

3. The wheel section and A wheel comprising a tire portion attached to the outer circumference of the wheel portion, The outer surface of the wheel portion is subjected to plasma surface treatment.

4. A wheel according to any one of claims 1 to 3, wherein an adhesive layer is formed between the outer circumferential surface of the wheel portion and the inner circumferential surface of the tire portion.

5. The wheel section and A method for manufacturing a wheel comprising a tire portion attached to the outer circumference of the wheel portion, A method for manufacturing a wheel, comprising: applying a plasma surface treatment to the outer surface of the wheel portion; arranging a mold so as to cover the outer surface of the wheel portion; injecting a resin composition into the mold to form the tire portion on the outer circumference of the wheel portion.

6. The method for manufacturing a wheel according to claim 5, wherein an adhesive is applied to the outer circumferential surface of the surface-treated wheel portion, and then the resin composition is injected into the mold.

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