Non-pneumatic tire and method for manufacturing a non-pneumatic tire

Abstract

The objective is to provide a non-pneumatic tire with improved electrostatic properties. [Solution] A non-pneumatic tire 1 comprising an inner cylinder 2 fitted onto a wheel, an outer cylinder 3 surrounding the inner cylinder 2 from the outside in the tire radial direction, a plurality of connecting members 4 arranged between the inner cylinder 2 and the outer cylinder 3 along the tire circumferential direction to connect the two cylinders, and a tread member 5 provided on the outer side of the outer cylinder 3 in the tire radial direction, wherein the inner cylinder 2, outer cylinder 3 and connecting members 4 are made of a resin composition, and at least on the connecting members 4 a conductive ink layer 6 mainly composed of one of the following materials is formed so as to be connected across the inner cylinder and the outer cylinder.

Description

Technical Field

[0001] The present disclosure relates to a non-pneumatic tire and a method for manufacturing a non-pneumatic tire.

Background Art

[0002] In recent years, in order to avoid the occurrence of punctures, tires that do not need to be filled with pressurized air inside have been proposed.

[0003] For example, in Patent Document 1 below, an airless tire includes an annular tread portion that contacts the road surface, an annular inner peripheral portion that is located inside the tread portion in the tire radial direction and contacts a conductive wheel, and a plurality of connecting portions that connect the tread portion and the inner peripheral portion. The tread portion includes a first portion that contacts the road surface and has conductivity, and a second portion on the inner peripheral portion side of the first portion. The second portion, the connecting portion, and the inner peripheral portion are disclosed to be formed of a resin containing carbon short fibers. Further, in Patent Document 2 below, an airless tire includes an annular tread portion that contacts the road surface, an annular inner peripheral portion that is located inside the tread portion in the tire radial direction and is connected to a conductive wheel, and a plurality of connecting portions that connect the tread portion and the inner peripheral portion. The tread portion includes a first portion that contacts the road surface and has conductivity, and a second portion on the inner tire radial direction inside of the first portion. The second portion, the connecting portion, and the inner peripheral portion are disclosed to be formed of a resin containing carbon black.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-mentioned Patent Documents 1 and 2, conductive materials such as carbon short fibers and carbon black are incorporated into tire frame members such as connecting members to improve the conductivity of the tire frame members and thereby improve the electrostatic properties of non-pneumatic tires. As described in Patent Documents 1 and 2 above, incorporating conductive materials into tire frame members can improve conductivity, but on the other hand, it can significantly affect the physical properties of non-pneumatic tires. While the influence of such material incorporation on the physical properties of non-pneumatic tires can be suppressed to some extent by controlling the amounts of various materials used, there are limits to how much this influence can be suppressed. Therefore, other means are needed to improve the electrostatic properties of non-pneumatic tires.

[0006] Therefore, the object of this disclosure is to solve the problems of the above-mentioned prior art and to provide a non-pneumatic tire with improved electrostatic properties and a method for manufacturing the same. [Means for solving the problem]

[0007] The gist of the present invention, which solves the above problems, is as follows.

[0008] [1] A non-pneumatic tire comprising: an inner cylinder fitted to a wheel; an outer cylinder surrounding the inner cylinder from the outside in the tire radial direction; a plurality of connecting members arranged between the inner cylinder and the outer cylinder along the tire circumferential direction for connecting the two cylinders; and a tread member provided on the outer side of the outer cylinder in the tire radial direction, The inner cylinder, the outer cylinder, and the connecting member are made of a resin composition. A non-pneumatic tire, wherein at least one conductive ink layer, mainly composed of (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin, is formed on the connecting member so as to connect the inner cylinder and the outer cylinder. The non-pneumatic tires described in [1] above have improved electrostatic properties.

[0009] [2] The non-pneumatic tire according to [1], wherein the conductive ink layer comprises carbon black and / or graphite. The non-pneumatic tires described in [2] above have improved electrostatic properties.

[0010] [3] The non-pneumatic tire according to [1] or [2], wherein the conductive ink layer does not contain a metallic conductive material. The non-pneumatic tires described in [3] above have improved electrostatic properties before and after driving.

[0011] [4] The non-pneumatic tire according to any one of [1] to [3], wherein the conductive ink layer is formed on at least one of the axial side surface of the non-pneumatic tire of the connecting member and the circumferential side surface of the non-pneumatic tire of the connecting member. The non-pneumatic tires described in [4] above have improved electrostatic properties and excellent adhesion.

[0012] [5] The non-pneumatic tire according to any one of [1] to [4], wherein the conductive ink layer is formed to be in contact with the wheel and the tread member. The non-pneumatic tires described in [5] above have improved electrostatic properties.

[0013] [6] The non-pneumatic tire according to any one of [1] to [5], wherein the conductive ink layer has a thickness of 0.01 to 1 mm. The non-pneumatic tires described in [6] above have improved electrostatic properties and superior peel resistance.

[0014] [7] The conductive ink layer has a surface resistivity of 1 × 10⁻⁶ before and after running a non-pneumatic tire on a durability drum tester for 20,000 km. 10 A non-pneumatic tire, less than or equal to Ω, as described in any of [1] to [6]. The non-pneumatic tires described in [7] above have improved electrostatic properties before and after driving.

[0015] [8] A method for manufacturing a non-pneumatic tire according to any one of [1] to [7], a step (1) of adjusting the viscosity of the conductive ink for forming the conductive ink layer, a step (2) of applying the conductive ink whose viscosity has been adjusted in the step (1) at least onto the connecting member, a step (3) of drying the conductive ink applied in the step (2), the method for manufacturing a non-pneumatic tire including these steps. According to the method for manufacturing a non-pneumatic tire described in the above [8], a non-pneumatic tire with improved chargeability can be manufactured.

Effect of the Invention

[0016] According to the present disclosure, a non-pneumatic tire with improved chargeability and a method for manufacturing the same can be provided.

Brief Description of the Drawings

[0017] [Figure 1] It is an explanatory view seen from the side of the tire schematically showing the configuration of the non-pneumatic tire according to an embodiment of the present disclosure. [Figure 2] It is a cross-sectional view of the connecting member in the non-pneumatic tire according to an embodiment of the present disclosure cut in the tire width direction.

Mode for Carrying Out the Invention

[0018] Hereinafter, the non-pneumatic tire and the method for manufacturing the non-pneumatic tire of the present disclosure will be illustrated in detail based on their embodiments.

[0019] The compounds described in this specification may be partially or entirely derived from fossil resources, may be derived from biological resources such as plant resources, or may be derived from recycled resources such as used tires. Further, they may be derived from a mixture of any two or more of fossil resources, biological resources, and recycled resources.

[0020] In this specification, "skeletal member" means a member that constitutes the skeleton of a non-pneumatic tire, more specifically, a member that supports the tread member from the inside to the outside of the tire in order to maintain the shape of the tire tread. Skeletal members include, for example, the inner cylinder, outer cylinder, and connecting members (spoke structure) in a non-pneumatic tire (hereinafter, these may be collectively referred to as "connecting members, etc.").

[0021] <Airless tires> The non-pneumatic tire of this embodiment is A non-pneumatic tire comprising: an inner cylinder fitted to the wheel; an outer cylinder surrounding the inner cylinder from the outside in the tire radial direction; a plurality of connecting members arranged between the inner cylinder and the outer cylinder along the tire circumferential direction, connecting the two cylinders together; and a tread member provided on the outer side of the outer cylinder in the tire radial direction, The inner cylinder, the outer cylinder, and the connecting member are made of a resin composition. At least one conductive ink layer, mainly composed of (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin, is formed on the connecting member so as to connect the inner cylinder and the outer cylinder. The connecting members and other structural components of non-pneumatic tires are typically made of resin compositions with low conductivity. As a result, static electricity generated by the vehicle is not released to the ground, causing the tires to become charged. However, the above-mentioned non-pneumatic tire is formed so that a conductive ink layer is connected between the inner and outer cylinders, at least on the connecting member. Because this conductive ink layer has high conductivity, static electricity can be released through it. Therefore, the non-pneumatic tire of this embodiment has improved electrostatic properties. Furthermore, since conductive paths can be created in the non-pneumatic tire by applying a conductive ink layer to the non-pneumatic tire component and drying it, it also offers excellent workability.

[0022] First, the configuration of the non-pneumatic tire of this embodiment (hereinafter sometimes simply referred to as "tire") will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the configuration of a non-pneumatic tire 1 according to one embodiment of the present disclosure, as viewed from the side of the tire. In the drawings used in the following description, the scale has been appropriately changed to make each component recognizable.

[0023] As shown in Figure 1, the non-pneumatic tire 1 of this embodiment comprises an inner cylinder 2 fitted onto a wheel (not shown), an outer cylinder 3 surrounding the inner cylinder 2 from the outside in the tire radial direction, and multiple elastically deformable connecting members 4 arranged between the inner cylinder 2 and the outer cylinder 3 along the tire circumferential direction, which connect the inner cylinder 2 and the outer cylinder 3 so that they can be displaced relative to each other. A tread member 5 is fitted onto the outer circumferential surface of the outer cylinder 3. This non-pneumatic tire 1 is used on wheelchairs (especially electric wheelchairs), bicycles, motorcycles, golf carts, automobiles, etc. (hereinafter, these are collectively referred to simply as vehicles).

[0024] Here, the inner cylinder 2, outer cylinder 3, and tread member 5 are formed in an annular shape, and their respective central axes are located on a common axis. In this specification, this common axis is referred to as the central axis O, and the direction along the central axis O is referred to as the tire width direction. Furthermore, in a side view from the tire width direction, the direction that circles around the central axis O is referred to as the tire circumferential direction, and the direction perpendicular to this central axis O is referred to as the tire radial direction.

[0025] The inner cylinder 2 is attached to the vehicle's axle (not shown) via a wheel. The wheel and axle can be made of metal materials such as aluminum, aluminum alloy, or steel. The central axes of the inner cylinder 2 and the outer cylinder 3 are coaxial with the central axis O. The inner cylinder 2, the outer cylinder 3, and the connecting member 4 are positioned such that their respective centers in the tire width direction coincide.

[0026] In this embodiment, the inner cylinder 2, outer cylinder 3, and connecting member 4 may be integrally formed from a resin composition. This allows the inner cylinder 2, outer cylinder 3, and connecting member 4 to be molded by injection molding, making them suitable for mass production. The inner cylinder 2, outer cylinder 3, and connecting member 4 may each be formed as separate components.

[0027] The tread member 5 may be formed from, for example, vulcanized rubber obtained by vulcanizing a rubber composition including natural rubber, or from a thermoplastic material. Examples of thermoplastic materials include polyurethane resin, polyolefin resin, polyvinyl chloride resin, and polyamide resin. From the viewpoint of wear resistance, it is preferable to form the tread member 5 from vulcanized rubber. In this embodiment, an adhesive layer (not shown) may be provided between the outer cylinder 3 and the tread member 5 to interpose the joining of the outer cylinder 3 and the tread member 5. A commercially available adhesive can be used for the adhesive layer. For example, cyanoacrylate adhesives or epoxy adhesives can be used, and specifically, Aron Alpha EXTRA 2000 (manufactured by Toagosei Co., Ltd.) can be used, but it is not limited to these.

[0028] The connecting member 4 is formed as a curved rectangular plate, with its front and back surfaces facing the tire circumferential direction and its sides facing the tire width direction. The connecting member 4 is made of an elastically deformable material and connects the outer circumferential surface of the inner cylinder 2 and the inner circumferential surface of the outer cylinder 3 in a manner that allows for relative elastic displacement. Multiple connecting members 4 are arranged at equal intervals in the tire circumferential direction. In Figure 1, there are 30 connecting members 4, but the number of connecting members 4 in the non-pneumatic tire 1 of this embodiment is not limited to this.

[0029] Each of the multiple connecting members 4 has an inner portion 4a connected to the inner cylinder 2 and an outer portion 4b connected to the outer cylinder 3. The inner portion 4a and the outer portion 4b are connected to each other at the center of the connecting member 4 in the tire radial direction. When driving, the connecting member 4 elastically deforms under load, absorbing vibrations transmitted from the ground to the vehicle.

[0030] In the non-pneumatic tire 1 according to this embodiment, the inner cylinder 2, outer cylinder 3, and connecting member 4 of the non-pneumatic tire 1 are sometimes collectively referred to as the skeletal member, and it is preferable that the inner cylinder 2, outer cylinder 3, and connecting member 4 are made of a resin composition described later. Furthermore, in the non-pneumatic tire 1 according to this embodiment, different resin compositions may be used for the inner cylinder 2, outer cylinder 3, and connecting member 4 that constitute the skeletal member.

[0031] Furthermore, in the non-pneumatic tire 1 of this embodiment, the conductive ink layer 6 is formed so as to be connected to at least the connecting member 4 and extending across the inner cylinder 2 and the outer cylinder 3. By forming the conductive ink layer 6 so as to be connected to at least the connecting member 4 and extending across the inner cylinder 2 and the outer cylinder 3, a conductive path can be provided. In addition, in the non-pneumatic tire 1 of this embodiment, the conductive ink layer 6 is formed at least on the connecting member 4, but it may also be formed extending across the inner cylinder 2 and / or the outer cylinder 3. That is, the conductive ink layer 6 may be formed so as to be connected across the connecting member 4 and the inner cylinder 2, the connecting member 4 and the outer cylinder 3, or the connecting member 4, the inner cylinder 2 and the outer cylinder 3.

[0032] Preferably, the conductive ink layer 6 is formed on at least one of the axial side surfaces of the connecting member 4 facing the non-pneumatic tire 1 and the circumferential side surfaces of the connecting member 4 facing the non-pneumatic tire 1. That is, the conductive ink layer 6 may be formed on at least one of the surfaces of the connecting member 4 facing the tire width direction (front and / or back surface), or on at least one of the surfaces facing the tire circumferential direction (side surface). Alternatively, the conductive ink layer 6 may be formed to cover the entire surface of the connecting member 4.

[0033] Furthermore, the conductive ink layer 6 may be formed on only some of the multiple connecting members 4, or it may be formed on all of the connecting members 4.

[0034] (Conductive ink layer) In the non-pneumatic tire 1 of this embodiment, the conductive ink layer 6 is formed on at least the connecting member 4, as shown in Figure 2. As mentioned above, the conductive ink layer 6 may also be formed on the inner cylinder 2 and / or outer cylinder 3 in addition to the connecting member 4. That is, the conductive ink layer 6 may be continuously formed on the skeletal member. Furthermore, it is preferable that the conductive ink layer is formed so as to be in contact with the wheel and the tread member. This is thought to allow static electricity to be released more easily, thereby further improving the chargeability.

[0035] In the non-pneumatic tire 1 of this embodiment, the conductive ink layer 6 mainly consists of one of the following materials: (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin. Here, "main component" means the component that is present in the largest proportion in the conductive ink layer 6. The conductive ink layer 6 can be formed using a conductive ink mainly composed of one of the following materials: (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin.

[0036] A conductive ink mainly composed of one of the following materials is (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin, and it is preferable that the conductive ink contains (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin, conductive powder, and a solvent. That is, a conductive ink layer formed with conductive ink may consist of (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin containing conductive powder. Examples of commercially available conductive inks include Polycalm PTP-G1501 (manufactured by Pluscoat Co., Ltd.), Air Race ESM500cb (manufactured by Edogawa Gosei Co., Ltd.), Air Race EMI768N (manufactured by Edogawa Gosei Co., Ltd.), Polycalm G2028 (manufactured by Pluscoat Co., Ltd.), Polycalm PCS-S2117 (manufactured by Pluscoat Co., Ltd.), Polycalm PCS-1949CG (manufactured by Pluscoat Co., Ltd.), and the like.

[0037] Examples of conductive powders that can be used include carbon black, graphite, and metallic conductive materials.

[0038] The conductive ink preferably contains carbon black and / or graphite. The carbon black and graphite can contribute to the conductivity of the conductive ink layer.

[0039] The carbon black mentioned above is not particularly limited and includes, for example, furnace carbon such as HAF, ISAF, and SAF grades, as well as channel black, thermal black, and acetylene black. These carbon blacks may be used individually or in combination of two or more types.

[0040] Furthermore, conductive inks may contain metallic conductive materials as components that provide conductivity. Examples of metallic conductive materials include elemental metals and metallic compounds. Examples of metallic conductive materials include copper, iron, nickel, palladium, platinum, gold, silver, aluminum, tungsten, and alloys thereof. Preferably, the conductive ink does not contain metallic conductive materials. If the conductive ink contains metallic conductive materials, these materials can become failure points when a conductive layer is formed using the conductive ink. By not including these metallic conductive materials, the conductive ink layer exhibits superior scratch resistance and maintenance of conductivity after deformation, which in turn results in a conductive component for tires with improved scratch resistance and electrostatic properties.

[0041] The solvent is not particularly limited as long as it can dissolve (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin. Among these, high-boiling point solvents such as toluene, ethylene glycol, ethylene glycol monoether, and N-methyl-2-pyrrolidone (NMP), which do not evaporate easily during printing, are preferred. These solvents may be used individually or in combination of two or more.

[0042] In the conductive ink layer 6, the carbon black content is not particularly limited and can be adjusted as appropriate to balance conductive performance with other physical properties.

[0043] In the conductive ink layer 6, the graphite content is not particularly limited and can be adjusted as appropriate to balance conductive performance with other physical properties.

[0044] The conductive ink layer 6 may contain a metallic conductive material. The metallic conductive material can impart conductivity to the conductive ink layer 6.

[0045] In the non-pneumatic tire of this embodiment, it is particularly preferable that the conductive ink layer 6 does not contain a metallic conductive material. If the conductive ink layer 6 contains a metallic conductive material, poor adhesion between the metallic conductive material and the binder resin of the conductive ink layer is likely to occur, resulting in a deterioration of conductivity after driving.

[0046] Examples of metallic conductive materials include individual metals and metallic compounds. Examples of metallic conductive materials include copper, iron, nickel, palladium, platinum, gold, silver, aluminum, tungsten, and alloys thereof.

[0047] The conductive ink layer 6 may contain further components in addition to the above-mentioned (A) polyurethane resin, (B) polyester resin, (C) acrylic resin, conductive powder, etc. Examples of such further components include crosslinking agents, weather-resistant anti-aging agents, heat-resistant anti-aging agents, moisture-resistant heat additives, antistatic agents, lubricants, crystal nucleating agents, tackifiers, anti-fogging agents, mold release agents, plasticizers, fillers, pigments, dyes, fragrances, flame retardants, etc. The content of these further components can be within a range that does not impair the effects of the present invention.

[0048] Furthermore, commercially available conductive inks can be used to form the conductive ink layer 6. (A) Examples of conductive inks mainly composed of polyurethane resin include Polycalm G1501. (B) Examples of conductive inks mainly composed of polyester resin include AirRace ESM500cb and AirRace EMI768N (manufactured by Edogawa Gosei Co., Ltd.). (C) Examples of conductive inks mainly composed of acrylic resin include Polycalm G2028, Polycalm PCS-S2117 and Polycalm PCS-1949CG (all manufactured by Pluscoat Co., Ltd.).

[0049] Furthermore, the conductive ink layer 6 is preferably 0.01 to 1 mm thick. Having the conductive ink layer 6 within this thickness range improves electrostatic properties and results in a non-pneumatic tire with superior adhesion. From the viewpoint of adhesion, the thickness of the conductive ink layer 6 is more preferably 0.5 mm or less, and even more preferably 0.25 mm or less. From the viewpoint of conductivity, it is more preferably 0.01 mm or more, and even more preferably 0.02 mm or more.

[0050] The adhesion of the conductive ink layer 6 can be measured using a grid test in accordance with JIS K5600. In a grid test compliant with JIS K5600, the conductive ink layer 6 preferably has a ratio of (number of squares that have not peeled off) / (total number of squares) of 20 / 25 or more, more preferably 23 / 25 or more, and even more preferably 24 / 25 or more.

[0051] When the conductive ink layer 6 was subjected to a 20,000 km run on a non-pneumatic tire 1 in a durability drum test machine, the surface resistivity before and after the run was 1 × 10⁻⁶. 10 It is preferable that the resistance is Ω or less. When the non-pneumatic tire 1 is driven for 20,000 km on a durability drum tester, the surface resistivity of the conductive ink layer 6 before and after driving is 1 × 10⁻⁶. 10If the resistance is less than Ω, the electrostatic charge before and after travel is improved. Furthermore, the surface resistivity before and after travel is 1 × 10⁻⁶ 0 It may be Ω or higher. When the conductive ink layer 6 was subjected to a 20,000 km run on a non-pneumatic tire 1 in a durability drum tester, the surface resistivity of the conductive ink layer 6 before running was 1 × 10⁻⁶. 8 It is more preferable that it be less than or equal to Ω, and 1 × 10 7 It is even more preferable that the resistivity is less than or equal to Ω. Furthermore, when the conductive ink layer 6 is subjected to a 20,000 km run on a non-pneumatic tire 1 in a durability drum tester, the surface resistivity after the run is 1 × 10⁻⁶. 8 It is more preferable that it be less than or equal to Ω, and 1 × 10 7 It is even more preferable that it be less than or equal to Ω. The above upper and lower limits can be combined in any way. The surface resistivity of the conductive ink layer 6 was measured using a tester at room temperature (23°C).

[0052] (Skeleton members) In the non-pneumatic tire 1 of this embodiment, the inner cylinder 2, outer cylinder 3, and connecting member 4 are made of a resin composition. These inner cylinder 2, outer cylinder 3, and connecting member 4 are sometimes collectively referred to as the skeletal members. In this specification, the connecting member 4 is sometimes described as a representative of the skeletal members, but a similar description can be applied to the inner cylinder 2 and outer cylinder 3. The following describes the resin compositions that constitute the skeletal members, such as the connecting member 4.

[0053] In the non-pneumatic tire 1 of this embodiment, the resin composition used for the inner cylinder 2, outer cylinder 3, and connecting member 4 preferably has a flexural modulus of elasticity at -20°C in accordance with ISO 178 of 247 MPa or less, more preferably 234 MPa or less, even more preferably 170 MPa or less, and usually 80 MPa or more, preferably 90 MPa or more. If the flexural modulus of elasticity at -20°C exceeds 247 MPa, the inner cylinder 2, outer cylinder 3, and connecting member 4 become too hard, causing vibrations transmitted from the tire to become more intense and worsening the ride comfort. In addition, the inner cylinder 2, outer cylinder 3, and connecting member 4 (skeletal members) become too hard and brittle, thus worsening their durability. Furthermore, if the flexural modulus of elasticity at -20°C is 90 MPa or more, a good balance of ride comfort and durability in low-temperature environments is achieved.

[0054] In the non-pneumatic tire 1 of this embodiment, the resin composition used for the inner cylinder 2, outer cylinder 3, and connecting member 4 preferably has a flexural modulus of elasticity at 60°C of 32 MPa or higher, more preferably 34 MPa or higher, even more preferably 36 MPa or higher, and usually 90 MPa or lower, preferably 70 MPa or lower, in accordance with ISO 178. If the flexural modulus of elasticity at 60°C is less than 32 MPa, the inner cylinder 2, outer cylinder 3, and connecting member 4 become too soft, which may result in a deterioration of ride comfort and reduced durability when a vehicle equipped with the non-pneumatic tire 1 is driven. Furthermore, if the flexural modulus of elasticity at 60°C is 70 MPa or lower, a good balance of ride comfort and durability in high-temperature environments is achieved.

[0055] The flexural modulus at 0°C of the resin composition used in the inner cylinder 2, outer cylinder 3, and connecting member 4 is usually 61 MPa or higher, preferably 70 MPa or higher, and usually 159 MPa or lower, preferably 130 MPa or lower. If the flexural modulus at 0°C is 70 MPa or higher, the ride comfort in low-temperature environments is further improved, and if the flexural modulus at 0°C is 130 MPa or lower, the ride comfort and durability in low-temperature environments are improved in a well-balanced manner.

[0056] The flexural modulus at 23°C of the resin composition used for the inner cylinder 2, outer cylinder 3, and connecting member 4 is usually 53 MPa or higher, preferably 60 MPa or higher, and usually 127 MPa or lower, preferably 115 MPa or lower. If the flexural modulus at 23°C is 60 MPa or higher, the ride comfort at room temperature is further improved, and if the flexural modulus at 23°C is 115 MPa or lower, the ride comfort and durability at room temperature are improved in a well-balanced manner.

[0057] The flexural modulus at 40°C of the resin composition used in the inner cylinder 2, outer cylinder 3, and connecting member 4 is usually 40 MPa or higher, preferably 44 MPa or higher, and usually 96 MPa or lower, preferably 84 MPa or lower. If the flexural modulus at 40°C is 44 MPa or higher, the ride comfort in high-temperature environments is further improved, and if the flexural modulus at 40°C is 84 MPa or lower, the ride comfort and durability in high-temperature environments are improved in a well-balanced manner.

[0058] The resin component of the resin composition used for the inner cylinder 2, outer cylinder 3, and connecting member 4 is preferably a thermoplastic elastomer or a thermoplastic resin, with a thermoplastic elastomer being more preferred. In addition to the resin component, various additives can be added to the resin composition. The resin component content in the resin composition is preferably 80% by mass or more, and more preferably 90% by mass or more. Here, thermoplastic elastomers and thermoplastic resins are polymer compounds that soften and flow as the temperature rises, and become relatively hard and strong when cooled. In this specification, polymer compounds that soften and flow as the temperature rises, become relatively hard and strong when cooled, and have rubber-like elasticity are referred to as thermoplastic elastomers, while polymer compounds that soften and flow as the temperature rises, become relatively hard and strong when cooled, and do not have rubber-like elasticity are referred to as thermoplastic resins. Furthermore, "thermoplastic elastomer" refers to a thermoplastic resin material having hard segments and soft segments in its molecule. More specifically, it refers to a thermoplastic resin material consisting of an elastic polymer compound, comprising a copolymer having a crystalline, high-melting-point hard segment and an amorphous, low-glass transition-temperature soft segment. Note that the thermoplastic elastomer in this invention does not include vulcanized rubbers such as natural rubber or synthetic rubber.

[0059] Examples of the aforementioned thermoplastic elastomers include polyester-based thermoplastic elastomers (TPC), polyamide-based thermoplastic elastomers (TPA), polyolefin-based thermoplastic elastomers (TPO), and polystyrene-based thermoplastic elastomers (TPS). Among these, polyester-based thermoplastic elastomers (TPC) are preferred from the viewpoint of durability and cost. The aforementioned polyester thermoplastic elastomer (TPC) is an elastic polymer compound, and refers to a thermoplastic resin material comprising a copolymer having a crystalline polymer constituting a hard segment with a high melting point and an amorphous polymer constituting a soft segment with a low glass transition temperature, wherein the main chain of the polymer constituting the hard segment has an ester bond.

[0060] Aromatic polyesters can be used as the crystalline polyester that forms the hard segments of the polyester-based thermoplastic elastomer (TPC). Aromatic polyesters can be formed, for example, from aromatic dicarboxylic acids or their ester-forming derivatives and aliphatic diols. Examples of aromatic polyesters that form hard segments include polyethylene terephthalate, polybutylene terephthalate, polystyrene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, with polybutylene terephthalate being preferred. One suitable aromatic polyester for forming the hard segment is polybutylene terephthalate derived from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol. Furthermore, a dicarboxylic acid component such as isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sulfoisophthalic acid, or ester-forming derivatives thereof, and ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol The polyester may be derived from diol components such as 1,4-cyclohexanedimethanol, tricyclodecanedimethylol, xylylene glycol, bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4-(2-hydroxy)phenyl]sulfone, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 4,4'-dihydroxy-p-terphenyl, or 4,4'-dihydroxy-p-quarterphenyl, or a copolymer polyester obtained by using two or more of these dicarboxylic acid and diol components in combination.

[0061] Examples of polymers that form the soft segments of the polyester-based thermoplastic elastomer (TPC) include polymers selected from aliphatic polyethers and aliphatic polyesters. Examples of the aliphatic polyether include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide addition polymers of poly(propylene oxide) glycol, copolymers of ethylene oxide and tetrahydrofuran, and the like. Examples of the aliphatic polyester include poly(ε-caprolactone), polyenanthractone, polycapryloractone, polybutylene adipate, and polyethylene adipate. Among these aliphatic polyethers and aliphatic polyesters, poly(tetramethylene oxide) glycol, ethylene oxide addition polymers of poly(propylene oxide) glycol, poly(ε-caprolactone), polybutylene adipate, polyethylene adipate, etc. are preferred from the viewpoint of the elastic properties of the resulting copolymer.

[0062] The polyester-based thermoplastic elastomer can be synthesized by copolymerizing a polymer that forms a hard segment and a polymer that forms a soft segment using a known method. Alternatively, commercially available polyester-based thermoplastic elastomers can be used, such as the "Perprene" series from Toyobo Co., Ltd. (P30B, P40B, P40H, P-46D01, P55B, P70B, P90B, P120B, P150B, P280B, P450B, P150M, S1001, S2001, S5001, S6001, S9001, etc.) and the "Hytrel" series from Toray DuPont (e.g., 3046, 5557, 5577, 5577R-07, 6347, 4047, 4767, 4767N, 4777, etc.).

[0063] The polyamide-based thermoplastic elastomer (TPA) is an elastic polymer compound, and is a thermoplastic resin material comprising a copolymer having a crystalline, high-melting-point hard segment and an amorphous, low-glass transition-temperature soft segment, wherein the main chain of the polymer constituting the hard segment has an amide bond (-CONH-). Examples of the polyamide-based thermoplastic elastomer include materials in which at least the polyamide constitutes a crystalline, high-melting-point hard segment, and other polymers (e.g., polyester, polyether, etc.) constitute an amorphous, low-glass transition-temperature soft segment.

[0064] The crystalline polyamides constituting the hard segment of the polyamide-based thermoplastic elastomer (TPA) include polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyethylenediamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), and polyhex Examples include aliphatic polyamides such as methylene sebaamide (nylon-6,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), and polydecamethylene adipamide (nylon-10,8), and crystalline aromatic polyamides obtained by polycondensation reactions of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids or derivatives thereof, such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid. Among these, nylon-6, nylon-6,6, and nylon-12 are preferred, with nylon-12 being more preferred.

[0065] Examples of polymers that constitute the soft segment of the polyamide-based thermoplastic elastomer (TPA) include polymers selected from polymethylene and aliphatic polyethers. Examples of the aliphatic polyether include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide addition polymers of poly(propylene oxide) glycol, copolymers of ethylene oxide and tetrahydrofuran, and the like.

[0066] The polyamide-based thermoplastic elastomer can be synthesized by copolymerizing the polymer forming the hard segment and the polymer forming the soft segment using a known method. Alternatively, commercially available polyamide-based thermoplastic elastomers can be used, such as the "UBESTA XPA" series from Ube Industries (e.g., XPA9063X1, XPA9055X1, XPA9048X2, XPA9048X1, XPA9040X1, XPA9040X2, XPA9044, XPA9048, XPA9055, etc.) and the "Vestamid" series from Daicel Eponic (e.g., E40-S3, E47-S1, E47-S3, E55-S1, E55-S3, EX9200, E50-R2).

[0067] The aforementioned polyolefin-based thermoplastic elastomer (TPO) is an elastic polymer compound, and refers to a thermoplastic resin material comprising a copolymer having a crystalline, high-melting-point hard segment and an amorphous, low-glass transition-temperature soft segment, wherein the polymer constituting the hard segment is a polyolefin such as polypropylene or polyethylene. Examples of the polyolefin-based thermoplastic elastomer include materials in which at least the polyolefin constitutes a hard segment that is crystalline and has a high melting point, and the polyolefin and other olefins constitute a soft segment that is amorphous and has a low glass transition point.

[0068] Examples of polyolefins that form the hard segments of the polyolefin-based thermoplastic elastomer include polypropylene, isotactic polypropylene, polyethylene, and poly-1-butene. Examples of polymers constituting the soft segment of the polyolefin-based thermoplastic elastomer include ethylene-propylene copolymer, propylene-1-hexene copolymer, propylene-4-methyl-1-pentene copolymer, propylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, ethylene-1-butene copolymer, 1-butene-1-hexene copolymer, and 1-butene-4-methyl-pentene.

[0069] The polyolefin-based thermoplastic elastomer can be synthesized by copolymerizing the polymer constituting the hard segment and the polymer constituting the soft segment using a known method. Furthermore, commercially available polyolefin-based thermoplastic elastomers can be used, such as Prime TPO® from Prime Polymer, and Tuffmer® and Notio® from Mitsui Chemicals.

[0070] The polystyrene-based thermoplastic elastomer (TPS) refers to an elastic polymer compound, a thermoplastic resin material comprising a copolymer having a polymer constituting a hard segment and a polymer constituting an amorphous soft segment with a low glass transition temperature, wherein the polymer constituting the hard segment is polystyrene or a polystyrene derivative. The polystyrene-based thermoplastic elastomer is not particularly limited, but examples include copolymers in which polystyrene constitutes a hard segment and an amorphous polymer constitutes a soft segment with a low glass transition temperature (e.g., polyethylene, polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, poly(2,3-dimethyl-butadiene), etc.).

[0071] The polystyrene-based thermoplastic elastomer can be synthesized by copolymerizing the polymer constituting the hard segment and the polymer constituting the soft segment by known methods such as block copolymerization. Furthermore, commercially available polystyrene-based thermoplastic elastomers can be used, such as Toughprene® and Toughtec® manufactured by Asahi Kasei Corporation, or Septon® manufactured by Kuraray Co., Ltd.

[0072] Examples of the thermoplastic resin include polyester resin, polyamide resin, polyolefin resin, and polystyrene resin. Among these, polyester resin is preferred from the viewpoint of durability and cost.

[0073] The polyester resin is a resin having ester bonds in its main chain. While the polyester resin is not particularly limited, crystalline polyester is preferred. Aromatic polyesters can be used as the crystalline polyester. Aromatic polyesters can be formed, for example, from an aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol. Examples of the aromatic polyester include polyethylene terephthalate, polybutylene terephthalate, polystyrene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, with polybutylene terephthalate being preferred.

[0074] One example of the aromatic polyester is polybutylene terephthalate derived from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol. Furthermore, a dicarboxylic acid component such as isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sulfoisophthalic acid, or ester-forming derivatives thereof, and a diol with a molecular weight of 300 or less {for example, ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol, and other aliphatic diols}. The polyester may be derived from alicyclic diols such as 1,4-cyclohexanedimethanol and tricyclodecanedimethylol, xylylene glycol, bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4-(2-hydroxy)phenyl]sulfone, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 4,4'-dihydroxy-p-terphenyl, 4,4'-dihydroxy-p-quarterphenyl, or other aromatic diols, or copolymerized polyesters using two or more of these dicarboxylic acid and diol components in combination. It is also possible to copolymerize polyfunctional carboxylic acid components with three or more functions, polyfunctional oxyacid components, and polyfunctional hydroxy components in a range of 5 mol% or less.

[0075] Commercially available polyester resins can also be used, such as the "DuraNex" series from Polyplastics Corporation (e.g., 2000, 2002, etc.), the NovaDuran series from Mitsubishi Engineering Plastics Corporation (e.g., 5010R5, 5010R3-2, etc.), the "Toraycon" series from Toray Industries, Inc. (e.g., 1401X06, 1401X31, 1401X70, etc.), and the "Planac" series from Toyobo Co., Ltd. (e.g., BT-1000).

[0076] The polyamide resin is a resin having an amide bond (-NHCO-) ​​in its main chain. Examples of the polyamide resin include polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyethylenediamine adipamide (nylon-2,6), polytetramethylene adipamide (nylon-4,6), polyhexamethylene adipamide (nylon-6,6), and polyhexamethylene sevacamide (nylon-6,1 Examples include aliphatic polyamides such as polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), and polydecamethylene adipamide (nylon-10,8), and crystalline aromatic polyamides obtained by polycondensation reactions of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids or derivatives thereof, such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid. Among these, nylon-6, nylon-6,6, and nylon-12 are preferred, with nylon-12 being more preferred.

[0077] As the polyamide resin, commercially available products can be used, for example, UBESTA manufactured by Ube Industries (e.g., 3014U, 3020U, etc.) and VESTAMID manufactured by Daicel Evonix (e.g., L1600, L1700, etc.).

[0078] The polyolefin resin has a main chain of olefin polymers such as ethylene, propylene, and 1-butene. Examples of the polyolefin resin include polyethylene, polypropylene, polybutene, cycloolefin resins, and copolymers of these resins. Among these, polyethylene, polypropylene, and ethylene-propylene copolymers are preferred, and polypropylene and ethylene-propylene copolymers are more preferred.

[0079] As the aforementioned polyolefin resin, commercially available products can be used, for example, Prime PP (registered trademark) manufactured by Prime Polymer Co., Ltd., and Novatec PP (registered trademark) and Wintec (registered trademark) manufactured by Nippon Polypropylene Co., Ltd.

[0080] The polystyrene resin is a polymer of styrene. Commercially available polystyrene resins can be used, such as Zarec® manufactured by Idemitsu Kosan Co., Ltd., Toyo Styrene® manufactured by Toyo Styrene Co., Ltd., and Sebian manufactured by Daicel Polymer Co., Ltd.

[0081] In the non-pneumatic tire 1 of this embodiment, it is preferable that the resin composition contains a thermoplastic elastomer having hard segments and soft segments in its molecule. A non-pneumatic tire using a resin composition containing a thermoplastic elastomer having hard segments and soft segments in its molecule as a skeletal member exhibits improved ride comfort over a wide temperature range, as well as improved durability.

[0082] Here, it is preferable that the thermoplastic elastomer is a polyester-based thermoplastic elastomer. Non-pneumatic tires using a resin composition containing a polyester-based thermoplastic elastomer as a skeletal member have improved ride comfort over a wide temperature range and also improved durability.

[0083] Furthermore, it is even more preferable that the hard segment of the polyester thermoplastic elastomer is polybutylene terephthalate. A resin composition containing a polyester thermoplastic elastomer in which the hard segment is polybutylene terephthalate has high strength, and a non-pneumatic tire using such a resin composition as a skeletal member has low deflection and particularly good ride comfort and durability.

[0084] The resin composition used for the skeletal member may contain additives in addition to the resin components such as the thermoplastic elastomer and thermoplastic resin mentioned above. Examples of additives to be added to the resin composition include weather-resistant anti-aging agents, heat-resistant anti-aging agents, moisture-resistant heat additives, antistatic agents, lubricants, crystal nucleating agents, tackifiers, anti-fogging agents, mold release agents, plasticizers, fillers, pigments, dyes, fragrances, and flame retardants. Among these, weather-resistant anti-aging agents, heat-resistant anti-aging agents, and moisture-resistant heat additives are preferred, and weather-resistant anti-aging agents and heat-resistant anti-aging agents are even more preferred. By adding weather-resistant anti-aging agents and heat-resistant anti-aging agents to the resin composition, the stability of the resin composition is improved, and non-pneumatic tires using such a resin composition as a skeletal member can maintain the desired properties over a long period of time. The total content of these additives is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the resin component.

[0085] The weather-resistant anti-aging agent is an additive that improves the weather resistance of the resin composition, and benzotriazole compounds and amine compounds (hindered amine compounds) are preferred as the weather-resistant anti-aging agent. Examples of the benzotriazole compounds include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, benzenepropanoic acid and ester compounds of 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C7-9 side chain and linear alkyl), octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert- A mixture of butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / Reaction products of polyethylene glycol 300: 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-butyl) Examples include tramethylbutylphenol, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole, and 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol]. Examples of the amine compounds include bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, and bis(2,2,6,6-tetramethyl-4-piperidyl) ) Sebacate, N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-N,N'-diformylhexamethylenediamine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], tetrakis(1,2,2,6,6 -Pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, reaction product of 1,2,2,6,6-pentamethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, 2,2,6,6-Te Examples include reaction products of tramethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidine-4-yl) carbonate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate. By adding a weather-resistant anti-aging agent to the resin composition, the weather resistance of the resin composition is improved, and non-pneumatic tires using such a resin composition as a structural member can maintain the desired properties over a long period of time. The amount of weather-resistant anti-aging agent added is preferably in the range of 1 to 5 parts by mass per 100 parts by mass of the resin component of the resin composition.

[0086] The aforementioned heat-resistant anti-aging agent is an additive that has the effect of improving the heat resistance of the resin composition, and a phenolic compound (hindered phenolic compound) is preferred as the heat-resistant anti-aging agent. Examples of the phenolic compound include 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, 2,4-di-tert-butyl-6-methylphenol, 1,6-hexanediol-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(3, 5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis-[2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionyloxy]-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5] Undecane, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 2,2'-butylidenebis(4,6-di-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenol acrylate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di Examples include -tert-pentylphenyl acrylate, 4,4'-thiobis(3-methyl-6-tert-butylphenol), 2-tert-butyl-4-methylphenol, 2,4-di-tert-butylphenol, 2,4-di-tert-pentylphenol, 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), bis-[3,3-bis-(4'-hydroxy-3'-tert-butylphenyl)-butanoic acid]-glycol ester, and N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]. By adding a heat-resistant anti-aging agent to the resin composition, the heat resistance of the resin composition is improved, and non-pneumatic tires using such a resin composition as a skeletal component can maintain the desired properties over a long period of time. The amount of heat-resistant anti-aging agent added is preferably in the range of 1 to 5 parts by mass per 100 parts by mass of the resin component of the resin composition.

[0087] The aforementioned moisture-resistant heat additive is an additive that improves the moisture-resistant heat properties of the resin composition. Preferably, the moisture-resistant heat additive is a carbodiimide compound or an epoxy compound, with epoxy compounds being more preferred. Specifically, the carbodiimide compound can be any compound having one or more carbodiimide groups in its molecule. Examples include monofunctional carbodiimide compounds such as N,N'-diisopropylcarbodiimide, N,N'-di(o-toluyl)carbodiimide, N,N'-dicyclohexylcarbodiimide, and N,N'-bis(2,6-diisopropylphenyl)carbodiimide; difunctional carbodiimide compounds such as p-phenylene-bis(2,6-xylylcarbodiimide), p-phenylene-bis(t-butylcarbodiimide), p-phenylene-bis(mesitylcarbodiimide), tetramethylene-bis(t-butylcarbodiimide), and cyclohexane-1,4-bis(methylene-t-butylcarbodiimide); and polyfunctional carbodiimide compounds such as condensates of isocyanate monomers. Among these, polyfunctional carbodiimide compounds are preferred. Here, a polyfunctional carbodiimide compound refers to a compound having two or more carbodiimide groups. Examples of such polyfunctional carbodiimide compounds include those commonly known by trade names such as Carbodilite LA-1 (manufactured by Nisshinbo), Carbodilite HMV-8CA (manufactured by Nisshinbo), Carbodilite HMV-15CA (manufactured by Nisshinbo), Elastostab H01 (manufactured by Nisshinbo), and Stabaxol P (manufactured by Rhein Chemie). One or more of these carbodiimide compounds can be used. Furthermore, as the epoxy compound, specifically, are epoxidized soybean oil, epoxidized linseed oil, phenyl glycidyl ether, allyl glycidyl ether, tert-butylphenyl glycidyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexyl carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexyl carboxylate, 2,3-epoxycyclohexylmethyl-3',4'-epoxycyclohexyl carboxylate, 4-(3,4-epoxy Xy-5-methylcyclohexyl)butyl-3',4'-epoxycyclohexyl carboxylate, 3,4-epoxycyclohexyl ethylene oxide, cyclohexylmethyl-3,4-epoxycyclohexyl carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-6'-methylsilohexyl carboxylate, bisphenol A diglycidyl ether, tetrabromobisphenol A glycidyl ether, diglycidyl ester of phthalate, diglycidyl ester of hexahydrophthalate, bis-epoxydicyclopentadie Nyl ether, bis-epoxyethylene glycol, bis-epoxycyclohexyl adipate, butadiene diepoxide, tetraphenylethylene epoxide, octyl epoxytalate, epoxidized polybutadiene, 3,4-dimethyl-1,2-epoxycyclohexane, 3,5-dimethyl-1,2-epoxycyclohexane, 3-methyl-5-tert-butyl-1,2-epoxycyclohexane, octadecyl-2,2-dimethyl-3,4-epoxycyclohexyl carboxylate, n-butyl-2,2-dimethyl-3,4-epoxycyclo Hexyl carboxylate, cyclohexyl-2-methyl-3,4-epoxycyclohexyl carboxylate, n-butyl-2-isopropyl-3,4-epoxy-5-methylcyclohexyl carboxylate, octadecyl-3,4-epoxycyclohexyl carboxylate, 2-ethylhexyl-3',4'-epoxycyclohexyl carboxylate, 4,6-dimethyl-2,3-epoxycyclohexyl-3',4'-epoxycyclohexyl carboxylate, 4,5-epoxy tetrahydrophthalic anhydride, 3-tert-butyl-4,Examples include 5-epoxy tetrahydrophthalic anhydride, diethyl-4,5-epoxy-cis-1,2-cyclohexyl dicarboxylate, and di-n-butyl-3-tert-butyl-4,5-epoxy-cis-1,2-cyclohexyl dicarboxylate. One or more of these epoxy compounds can be used. By adding a moisture-resistant heat additive to the resin composition, the moisture-resistant heat resistance of the resin composition is improved, and non-pneumatic tires using such a resin composition as a skeletal member can maintain the desired properties over a long period of time. The amount of moisture-resistant heat additive added is preferably in the range of 1 to 15 parts by mass per 100 parts by mass of the resin component of the resin composition.

[0088] The flexural modulus of the resin composition used in the aforementioned skeletal member at each temperature can be adjusted to a desired range by adjusting the type and blending ratio of the resin components used, and the type and amount of additives added. For example, when using a thermoplastic elastomer having hard segments and soft segments in its molecule as the resin component of the resin composition, selecting one with a high proportion of hard segments in the molecule can increase the flexural modulus of the resin composition at each temperature, while selecting one with a high proportion of soft segments in the molecule can decrease the flexural modulus of the resin composition at each temperature. Furthermore, the method for preparing the resin composition is not particularly limited. Additives may be added after mixing the resin components, or the resin components and additives may be mixed at the same time. Multiple resin components with additives already added may be mixed, or resin components with additives added may be mixed with resin components without additives. The aforementioned resin composition can be processed into skeletal members of a desired shape using various molding methods. Injection molding is preferred as the molding method.

[0089] <Manufacturing method for non-pneumatic tires> The non-pneumatic tire 1 of this embodiment is obtained by injection molding skeletal members such as the connecting member 4 using a known method, then applying a prepared conductive ink to the connecting member 4 (and the inner cylinder 2 and / or outer cylinder 3), and drying it to form a conductive ink layer 6. In addition, in the manufacturing method of the non-pneumatic tire, the connecting member 4 and the like may be subjected to surface treatment beforehand.

[0090] In a preferred embodiment, the method for manufacturing a non-pneumatic tire is: (1) A step of adjusting the viscosity of the conductive ink that forms the conductive ink layer 6, Step (2) involves applying the conductive ink, whose viscosity has been adjusted in step (1), to at least the connecting member 4. Preferably, the process includes a step (3) of drying the conductive ink applied in step (2). According to the above manufacturing method, non-pneumatic tires with improved electrostatic properties can be manufactured.

[0091] (Process (1)) The method for manufacturing the non-pneumatic tire 1 of this embodiment preferably includes a step (1) of adjusting the viscosity of the conductive ink that forms the conductive ink layer 6.

[0092] In step (1), the viscosity before application is adjusted based on a comprehensive assessment of adhesive performance, workability, etc.

[0093] Methods for adjusting the viscosity of conductive ink are not limited to these, but include, for example, dilution with an appropriate solvent.

[0094] (Process (2)) The method for manufacturing the non-pneumatic tire 1 of this embodiment preferably includes a step (2) of applying a conductive ink, whose viscosity has been adjusted in step (1), to at least the connecting member 4. In step (2), the conductive ink may be applied only to the connecting member 4, or to the connecting member 4 and the inner cylinder 2, or to the connecting member 4 and the outer cylinder 3, or to the connecting member 4, the inner cylinder 2 and the outer cylinder 3.

[0095] Known methods can be used to apply the conductive ink to the connecting member 4, etc., including, for example, spray coating, screen printing, and brush coating.

[0096] The amount of conductive ink applied in step (2) should be such that it results in the desired thickness of the conductive ink layer. For example, the conductive ink can be applied so that the thickness of the conductive ink layer is 0.01 to 1 mm.

[0097] (Step (3)) The manufacturing method of the non-pneumatic tire 1 of this embodiment preferably includes a step (3) of drying the conductive ink applied in step (2).

[0098] The method for drying conductive ink is not particularly limited, and known methods can be used. Examples of methods for drying conductive ink include leaving it to air dry indoors, using a spot dryer, a tunnel dryer, etc.

[0099] The conditions for performing step (3) can be adjusted according to the thickness of the conductive ink layer 6 and the viscosity of the conductive ink. For example, the conditions for performing step (3) include drying the conductive ink at 20 to 150°C for 0.1 to 60 hours. [Examples]

[0100] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0101] <Example 1> (1) Fabrication of structural members (connecting members, inner cylinder and outer cylinder) The skeletal components are fabricated by injection molding at 260°C using polyester thermoplastic elastomer (TPC, manufactured by Toray Celanese Co., Ltd., product name "Hytrel 5557").

[0102] (2) Adjustment of the viscosity of conductive ink Adjust the polyester-based conductive ink to a viscosity suitable for brush application, as needed.

[0103] (3) Manufacturing of non-pneumatic tires A polyester-based conductive ink is applied to the connecting members of the fabricated skeletal components, and dried at 150°C for 0.5 hours to form a conductive ink layer, thereby producing a non-pneumatic tire.

[0104] <Example 2> (1) Fabrication of structural members (connecting members, inner cylinder and outer cylinder) The skeletal members are fabricated in the same manner as in Example 1.

[0105] (2) Adjustment of the viscosity of conductive ink Adjust the acrylic conductive ink to a viscosity suitable for brush application, as needed.

[0106] (3) Manufacturing of non-pneumatic tires An acrylic conductive ink is applied to the connecting members of the fabricated skeletal components, and dried at room temperature (23°C) for 24 hours to form a conductive ink layer, thereby creating a non-pneumatic tire.

[0107] <Comparative Example 1> A non-pneumatic tire was manufactured in the same manner as in Example 1, except that a conductive ink layer was not provided.

[0108] <Measurement Method and Evaluation Method>

[0109] (1) Thickness of conductive ink For Examples 1 and 2, the thickness of the conductive ink formed on the skeletal member is measured using calipers. For Comparative Example 1, the thickness of the conductive ink formed on the skeletal member was measured using calipers. The measurement results are shown in Table 1.

[0110] (2) Conductivity (surface resistivity) For Examples 1 and 2, the surface resistivity of the conductive layer of the obtained non-pneumatic tires was measured using a Custom CDM-2000D tester under constant load at room temperature, before and after 20,000 km of driving on a drum durability tester at 60 km / h. For Comparative Example 1, the surface resistivity of the conductive layer of the obtained non-pneumatic tire was measured using a Custom CDM-2000D tester, under constant load at room temperature, before and after 20,000 km of driving on a drum durability tester at 60 km / h. The evaluation results are shown in Table 1.

[0111] (3) Adhesion For Examples 1 and 2, the adhesion of the conductive ink layer of the fabricated non-pneumatic tire was evaluated by a grid test in accordance with JIS K5600 after driving 20,000 km. For Comparative Example 1, the adhesion of the conductive ink layer was evaluated by a grid test in accordance with JIS K5600 after the fabricated non-pneumatic tire was driven for 20,000 km. A: 25 / 25 B:20 / 25~24 / 25 C: Less than 20 / 25 The evaluation results are shown in Table 1.

[0112] [Table 1]

[0113] *1 Polyester-based ink: Conductive ink mainly composed of polyester resin, manufactured by Edogawa Gosei Co., Ltd., product name "Air Race ESM500cb", contains carbon black. *2 Acrylic ink: Conductive ink mainly composed of acrylic resin, manufactured by Pluscoat Co., Ltd., product name "PCS-1949CG", contains carbon black. *3 OL: Overload, the resistance was too high to measure. In other words, it is highly charged.

[0114] Table 1 shows that the non-pneumatic tire of this embodiment has excellent conductivity, resulting in improved electrostatic properties. [Industrial applicability]

[0115] According to this disclosure, it is possible to provide a non-pneumatic tire with improved electrostatic properties and a method for manufacturing the same.

[0116] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is considered to be a technology that can contribute to "No. 12: Responsible Consumption and Production" and "No. 13: Climate Action," among others. [Explanation of Symbols]

[0117] 1: Non-pneumatic tires 2: Inner cylinder 3: Outer cylinder 4: Connecting member 4a: Inner part 4b:Outer part 5: Tread material O: Central axis D: Diameter in the radial direction of the tire 6: Conductive ink layer

Claims

1. A non-pneumatic tire comprising: an inner cylinder fitted to the wheel; an outer cylinder surrounding the inner cylinder from the outside in the tire radial direction; a plurality of connecting members arranged between the inner cylinder and the outer cylinder along the tire circumferential direction, connecting the two cylinders together; and a tread member provided on the outer side of the outer cylinder in the tire radial direction, The inner cylinder, the outer cylinder, and the connecting member are made of a resin composition. A non-pneumatic tire, wherein at least one conductive ink layer, mainly composed of one of the following materials: (A) polyurethane resin, (B) polyester resin, or (C) acrylic resin, is formed on the connecting member so as to connect the inner cylinder and the outer cylinder.

2. The non-pneumatic tire according to claim 1, wherein the conductive ink layer comprises carbon black and / or graphite.

3. The non-pneumatic tire according to claim 1, wherein the conductive ink layer does not contain a metallic conductive material.

4. The non-pneumatic tire according to claim 1, wherein the conductive ink layer is formed on at least one of the axial side surface of the connecting member of the non-pneumatic tire and the circumferential side surface of the connecting member of the non-pneumatic tire.

5. The non-pneumatic tire according to claim 1, wherein the conductive ink layer is formed to be in contact with the wheel and the tread member.

6. The non-pneumatic tire according to claim 1, wherein the conductive ink layer has a thickness of 0.01 to 1 mm.

7. The conductive ink layer, when a non-pneumatic tire is driven 20,000 km on a durability drum test machine, has a surface resistivity of 1 × 10⁻⁶ before and after driving. １０ A non-pneumatic tire according to claim 1, wherein the impedance is less than or equal to Ω.

8. A method for manufacturing a non-pneumatic tire according to claim 1, (1) A step of adjusting the viscosity of the conductive ink that forms the conductive ink layer, Step (2) involves applying the conductive ink, whose viscosity has been adjusted in step (1), to at least the connecting member, A method for manufacturing a non-pneumatic tire, comprising the step (3) of drying the conductive ink applied in step (2) above.

Images