Non-pneumatic tires

Abstract

The problem addressed by this invention is associated with providing a non-pneumatic tire which achieves both ride comfort and durability despite having a small diameter size. The solution therefor is a non-pneumatic tire (1) using a resin composition as a framework member, the non-pneumatic tire (1) being characterized in that a bending modulus of elasticity at −20°C compliant with ISO 178 of the resin composition is 247 MPa or less and a bending modulus of elasticity at 60°C compliant with ISO 178 thereof is 32 MPa or more, and a diameter D in the tire radial direction is 35 cm or less.

Description

[Technical Field]

[0001] The present invention relates to a non-pneumatic tire. [Background technology]

[0002] In recent years, in order to prevent punctures, tires that do not require pressurized air to be filled inside have been proposed. For example, Patent Document 1 listed below discloses a non-pneumatic tire that includes a mounting body attached to an axle, an inner cylindrical body fitted onto the mounting body, a ring member including an outer cylindrical body surrounding the inner cylindrical body from the outside in the tire radial direction, and connecting members that are arranged in multiple numbers between the inner cylindrical body and the outer cylindrical body along the tire circumferential direction and connect these two cylindrical bodies to each other so that they can be elastically displaced relative to each other. Furthermore, Patent Document 1 below discloses that ride comfort can be improved by integrally forming the ring members and connecting members of a non-pneumatic tire from a synthetic resin material with a specified ratio between the flexural modulus at -20°C and the flexural modulus at 60°C. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-125081 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inventors have conducted research and found that the non-pneumatic tire disclosed in Patent Document 1 has room for improvement in terms of both ride comfort and durability when the tire has a small diameter.

[0005] Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide a non-pneumatic tire that achieves both ride comfort and durability even when it has a small diameter size. [Means for solving the problem]

[0006] The gist and configuration of the present invention to solve the above problems is as follows.

[0007] The non-pneumatic tire of the present invention is a non-pneumatic tire using a resin composition for a frame member, The resin composition has a flexural modulus at −20° C. in accordance with ISO 178 of 247 MPa or less and a flexural modulus at 60° C. in accordance with ISO 178 of 32 MPa or more, The tire is characterized by having a radial diameter of 35 cm or less.

[0008] Here, in the present invention, the flexural modulus is a value obtained by a three-point bending test in accordance with "ISO178:2010 Method A." [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a non-pneumatic tire that achieves both ride comfort and durability even when it has a small diameter. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram seen from the side of a tire, schematically illustrating the configuration of a non-pneumatic tire according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The non-pneumatic tire of the present invention will be described in detail below by way of example based on embodiments thereof. The non-pneumatic tire of the present invention is a non-pneumatic tire using a resin composition for a frame member. Here, the frame members of the non-pneumatic tire refer to the members that make up the tire frame, more specifically, the members that support the tread members from the inside to the outside of the tire in order to maintain the shape of the tire tread, such as ring members (inner and outer cylinders) and connecting members (spoke structure) in a non-pneumatic tire.

[0012] In the non-pneumatic tire of the present invention, the resin composition used for the frame member has a flexural modulus of elasticity at -20°C in accordance with ISO178 of 247 MPa or less and a flexural modulus of elasticity at 60°C in accordance with ISO178 of 32 MPa or more, and the non-pneumatic tire of the present invention is characterized in that the diameter in the tire radial direction is 35 cm or less. The flexural modulus of a resin composition generally tends to decrease as the temperature increases. However, if the resin composition used for the skeletal member has a flexural modulus of 32 MPa or more at 60°C, the skeletal member will not become too soft even at relatively high temperatures, resulting in a good ride comfort and sufficient durability when a vehicle equipped with the non-pneumatic tire is driven. Furthermore, the flexural modulus of a resin composition generally tends to increase as the temperature decreases. However, if the resin composition used for the skeletal member has a flexural modulus of 247 MPa or less at -20°C, the skeletal member will not become too hard even at relatively low temperatures, resulting in a good ride comfort. Furthermore, the skeletal member will not become too hard and brittle, resulting in excellent durability. Therefore, the non-pneumatic tire of the present invention can achieve both ride comfort and durability over a wide temperature range, even when the tire has a small radial diameter of 35 cm or less.

[0013] The resin composition used for the skeletal member has a flexural modulus at -20°C of 247 MPa or less, preferably 234 MPa or less, more preferably 170 MPa or less, and usually 80 MPa or more, preferably 90 MPa or more. If the flexural modulus at -20°C exceeds 247 MPa, the skeletal member becomes too hard, causing vibrations transmitted from the tire to become intense and resulting in poor ride comfort. Furthermore, the skeletal member becomes too hard and brittle, resulting in poor durability. Furthermore, if the flexural modulus at -20°C is 90 MPa or more, a balanced improvement in ride comfort and durability in low-temperature environments is achieved.

[0014] The resin composition used for the skeletal member has a flexural modulus at 60°C of 32 MPa or more, preferably 34 MPa or more, and more preferably 36 MPa or more, and is usually 90 MPa or less, preferably 70 MPa or less. If the flexural modulus at 60°C is less than 32 MPa, the skeletal member becomes too soft, which may result in a deterioration in ride comfort and a decrease in durability when a vehicle equipped with a non-pneumatic tire is driven. Furthermore, if the flexural modulus at 60°C is 70 MPa or less, a balanced improvement in ride comfort and durability in high-temperature environments is achieved.

[0015] The resin composition used for the frame member has a flexural modulus at 0° C. of usually 61 MPa or more, preferably 70 MPa or more, and usually 159 MPa or less, preferably 130 MPa or less. If the flexural modulus at 0° C. is 70 MPa or more, ride comfort in low-temperature environments is further improved, and if the flexural modulus at 0° C. is 130 MPa or less, ride comfort and durability in low-temperature environments are improved in a balanced manner.

[0016] The resin composition used for the frame member has a flexural modulus at 23° C. of usually 53 MPa or more, preferably 60 MPa or more, and usually 127 MPa or less, preferably 115 MPa or less. If the flexural modulus at 23° C. is 60 MPa or more, the ride comfort at room temperature is further improved, and if the flexural modulus at 23° C. is 115 MPa or less, the ride comfort and durability at room temperature are improved in a balanced manner.

[0017] The resin composition used for the frame member has a flexural modulus at 40° C. of usually 40 MPa or more, preferably 44 MPa or more, and usually 96 MPa or less, preferably 84 MPa or less. If the flexural modulus at 40° C. is 44 MPa or more, ride comfort in high-temperature environments is further improved, and if the flexural modulus at 40° C. is 84 MPa or less, ride comfort and durability in high-temperature environments are improved in a balanced manner.

[0018] The resin component of the resin composition used for the skeletal member is preferably a thermoplastic elastomer or a thermoplastic resin, more preferably a thermoplastic elastomer. In addition to the resin component, various additives can be added to the resin composition. The content of the resin component in the resin composition is preferably 80% by mass or more, more preferably 90% by mass or more. Here, thermoplastic elastomers and thermoplastic resins are polymeric compounds that soften and flow with increasing temperature and become relatively hard and strong when cooled. In this specification, a distinction is made between these two compounds as follows: a thermoplastic elastomer is a polymeric compound that softens and flows with increasing temperature and becomes relatively hard and strong when cooled and has rubber-like elasticity; and a thermoplastic resin is a polymeric compound that softens and flows with increasing temperature and becomes relatively hard and strong when cooled and does not have rubber-like elasticity. Furthermore, the term "thermoplastic elastomer" refers to a thermoplastic resin material having hard and soft segments in its molecule, and more specifically, refers to a thermoplastic resin material that is an elastic polymer compound and is a copolymer having a polymer that constitutes a crystalline hard segment with a high melting point and a polymer that constitutes an amorphous soft segment with a low glass transition temperature. Note that the thermoplastic elastomer in this invention does not include vulcanized rubber such as natural rubber or synthetic rubber.

[0019] Examples of the thermoplastic elastomer include polyester thermoplastic elastomers (TPC), polyamide thermoplastic elastomers (TPA), polyolefin thermoplastic elastomers (TPO), polystyrene thermoplastic elastomers (TPS), etc. Among these, polyester thermoplastic elastomers (TPC) are preferred from the viewpoints of durability and cost.

[0020] The thermoplastic polyester elastomer (TPC) is a polymeric compound having elasticity, and is a thermoplastic resin material made of a copolymer having a polymer that constitutes a crystalline hard segment with a high melting point and a polymer that constitutes an amorphous soft segment with a low glass transition temperature, and has an ester bond in the main chain of the polymer that constitutes the hard segment.

[0021] The crystalline polyester forming the hard segment of the polyester-based thermoplastic elastomer (TPC) can be an aromatic polyester. The aromatic polyester can be formed, for example, from an aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol. Examples of the aromatic polyester forming the hard segment include polyethylene terephthalate, polybutylene terephthalate, polystyrene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, with polybutylene terephthalate being preferred. One of the suitable aromatic polyesters for forming the hard segment is polybutylene terephthalate derived from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol, and further includes polybutylene terephthalate derived from 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 an ester-forming derivative thereof, and ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol. and a diol component 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-quaterphenyl, or a copolymer polyester using two or more of these dicarboxylic acid components and diol components in combination.

[0022] Examples of the polymer that forms the soft segment 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, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide addition polymer of poly(propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran. Examples of the aliphatic polyester include poly(ε-caprolactone), polyenantholactone, polycaprylolactone, 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.

[0023] The polyester-based thermoplastic elastomer can be synthesized by copolymerizing a polymer forming a hard segment and a polymer forming a soft segment by a known method. Commercially available polyester-based thermoplastic elastomers include the "Pelprene" series manufactured by Toyobo Co., Ltd. (P30B, P40B, P40H, P-46D01, P55B, P70B, P90B, P120B, P150B, P280B, P450B, P150M, S1001, S2001, S5001, S6001, and S9001) and the "Hytrel" series manufactured by DuPont-Toray Co., Ltd. (e.g., 3046, 5557, 5577, 5577R-07, 6347, 4047, 4767, 4767N, and 4777).

[0024] The polyamide thermoplastic elastomer (TPA) is a polymeric compound having elasticity, and is a thermoplastic resin material made of a copolymer having a polymer that constitutes a crystalline hard segment with a high melting point and a polymer that constitutes an amorphous soft segment with a low glass transition temperature, and has an amide bond (-CONH-) in the main chain of the polymer that constitutes the hard segment. The polyamide-based thermoplastic elastomer may be a material in which at least a polyamide constitutes a crystalline hard segment with a high melting point, and another polymer (e.g., polyester, polyether, etc.) constitutes an amorphous soft segment with a low glass transition temperature.

[0025] Examples of 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), polylauryllactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), and polyhexamethylene adipamide (nylon-12). Examples include aliphatic polyamides such as 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 of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid, or their derivatives. Among these, nylon-6, nylon-6,6, and nylon-12 are preferred, with nylon-12 being more preferred.

[0026] Examples of the polymer constituting 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, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide addition polymer of poly(propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran.

[0027] The thermoplastic polyamide elastomer can be synthesized by copolymerizing the hard segment polymer and the soft segment polymer by a known method. Commercially available thermoplastic polyamide elastomers include the UBESTA XPA series manufactured by Ube Industries, Ltd. (e.g., XPA9063X1, XPA9055X1, XPA9048X2, XPA9048X1, XPA9040X1, XPA9040X2, XPA9044, XPA9048, and XPA9055) and the VESTAMID series manufactured by Daicel-Eponic Co., Ltd. (e.g., E40-S3, E47-S1, E47-S3, E55-S1, E55-S3, EX9200, and E50-R2).

[0028] The polyolefin thermoplastic elastomer (TPO) is a polymeric compound having elasticity, and is a thermoplastic resin material made of a copolymer having a polymer that constitutes a crystalline hard segment with a high melting point and a polymer that constitutes an amorphous soft segment with a low glass transition temperature, and the polymer that constitutes the hard segment is a polyolefin such as polypropylene or polyethylene. The polyolefin-based thermoplastic elastomer may be a material in which at least a polyolefin constitutes a crystalline hard segment with a high melting point, and the polyolefin and an olefin other than the polyolefin constitute an amorphous soft segment with a low glass transition point.

[0029] 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 copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1-pentene copolymers, propylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-4-methyl-pentene copolymers, ethylene-1-butene copolymers, 1-butene-1-hexene copolymers, and 1-butene-4-methyl-pentene.

[0030] The thermoplastic polyolefin elastomer can be synthesized by copolymerizing the polymer constituting the hard segment and the polymer constituting the soft segment by a known method. Commercially available products such as Prime TPO (registered trademark) manufactured by Prime Polymer Co., Ltd., and TAFMER (registered trademark) and NOTIO (registered trademark) manufactured by Mitsui Chemicals, Inc. can be used as the thermoplastic polyolefin elastomer.

[0031] The polystyrene-based thermoplastic elastomer (TPS) is a polymer compound having elasticity, and is a thermoplastic resin material made of a copolymer having a polymer constituting a hard segment and a polymer constituting an amorphous soft segment having a low glass transition temperature, and the polymer constituting the hard segment is polystyrene or a polystyrene derivative. The polystyrene-based thermoplastic elastomer is not particularly limited, but examples thereof include copolymers in which polystyrene constitutes hard segments and an amorphous polymer constitutes soft segments with a low glass transition temperature (e.g., polyethylene, polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, poly(2,3-dimethyl-butadiene), etc.).

[0032] The polystyrene-based thermoplastic elastomer can be synthesized by copolymerizing the polymer constituting the hard segment and the polymer constituting the soft segment by a known method such as block copolymerization. Commercially available polystyrene-based thermoplastic elastomers can be used, such as Tufprene (registered trademark) and Tuftec (registered trademark) manufactured by Asahi Kasei Corporation, and Septon (registered trademark) manufactured by Kuraray Co., Ltd.

[0033] Examples of the thermoplastic resin include polyester resin, polyamide resin, polyolefin resin, polystyrene resin, etc. Among these, polyester resin is preferred from the viewpoints of durability and cost.

[0034] The polyester resin is a resin having an ester bond in the main chain. The polyester resin is not particularly limited, but a crystalline polyester is preferred. An aromatic polyester can be used as the crystalline polyester. The aromatic polyester 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.

[0035] One example of the aromatic polyester is polybutylene terephthalate derived from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol. Further, there is also mentioned a polybutylene terephthalate derived from 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 an ester-forming derivative thereof, and a diol having a molecular weight of 300 or less {for example, an aliphatic diol such as ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, or decamethylene glycol}. The polyester may be a polyester derived from an alicyclic diol such as 1,4-cyclohexanedimethanol or tricyclodecanedimethylol, or an aromatic diol such as 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-quaterphenyl, or a copolymerized polyester containing two or more of these dicarboxylic acid components and diol components. It is also possible to copolymerize a trifunctional or higher polyfunctional carboxylic acid component, a polyfunctional oxyacid component, or a polyfunctional hydroxy component in an amount of 5 mol % or less.

[0036] As the polyester resin, commercially available products can be used, and examples thereof include the "Duranex" series (e.g., 2000, 2002, etc.) manufactured by Polyplastics Co., Ltd., the Novaduran series (e.g., 5010R5, 5010R3-2, etc.) manufactured by Mitsubishi Engineering Plastics Corporation, the "Trecon" series (e.g., 1401X06, 1401X31, 1401X70, etc.) manufactured by Toray Industries, Inc., and the "Planac" series (e.g., BT-1000) manufactured by Toyobo Co., Ltd.

[0037] The polyamide resin is a resin having an amide bond (-NHCO-) ​​in the 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), polylauryllactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), and polyhexamethylenesebacamide (nylon-6,1). Examples of suitable polyamides 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 of aromatic diamines such as metaxylenediamine and paraxylenediamine with dicarboxylic acids such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid, or derivatives thereof. Among these, nylon-6, nylon-6,6, and nylon-12 are preferred, with nylon-12 being more preferred.

[0038] As the polyamide resin, commercially available products can be used, and examples thereof include UBESTA (for example, 3014U, 3020U, etc.) manufactured by Ube Industries, Ltd. and VESTAMID (for example, L1600, L1700, etc.) manufactured by Daicel-Evonix.

[0039] The polyolefin resin has a main chain made of an olefin polymer such as ethylene, propylene, or 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.

[0040] As the polyolefin resin, commercially available products can be used, such as Prime PP (registered trademark) manufactured by Prime Polymer Co., Ltd., and Novatec PP (registered trademark) and Wintec (registered trademark) manufactured by Japan Polypropylene Co., Ltd.

[0041] The polystyrene resin is a polymer of styrene. Commercially available polystyrene resins may be used, such as Xalec (registered trademark) manufactured by Idemitsu Kosan Co., Ltd., Toyo Styrol (registered trademark) manufactured by Toyo Styrene Co., Ltd., and Cevian (registered trademark) manufactured by Daicel Polymers Ltd.

[0042] In the non-pneumatic tire of the present invention, the resin composition preferably contains a thermoplastic elastomer having hard and soft segments in its molecule. A non-pneumatic tire using a resin composition containing a thermoplastic elastomer having hard and soft segments in its molecule for its frame member has improved ride comfort over a wide temperature range and also improved durability.

[0043] The thermoplastic elastomer is preferably a polyester-based thermoplastic elastomer. A non-pneumatic tire using a resin composition containing a polyester-based thermoplastic elastomer for a frame member has further improved ride comfort over a wide temperature range and further improved durability.

[0044] Furthermore, it is more preferable that the hard segment of the polyester-based thermoplastic elastomer is polybutylene terephthalate. A resin composition containing a polyester-based thermoplastic elastomer whose hard segment is polybutylene terephthalate has high strength, and a non-pneumatic tire using such a resin composition for a frame member has small deflection and is particularly good in ride comfort and durability.

[0045] The resin composition used for the framework member may contain additives in addition to the resin components, such as the thermoplastic elastomer and thermoplastic resin, described above. Examples of additives that can be added to the resin composition include weather-resistant anti-aging agents, heat-resistant anti-aging agents, moist heat-resistant additives, antistatic agents, lubricants, crystal nucleating agents, tackifiers, anti-fog 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 moist heat-resistant additives are preferred, and weather-resistant anti-aging agents and heat-resistant anti-aging agents are more preferred. Adding a weather-resistant anti-aging agent or heat-resistant anti-aging agent to the resin composition improves the stability of the resin composition, and non-pneumatic tires using such a resin composition for the framework member can maintain desired properties over a long period of time. The total content of these additives is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the resin component.

[0046] The weather-resistant anti-aging agent is an additive that has the effect of improving the weather resistance of the resin composition, and the weather-resistant anti-aging agent is preferably a benzotriazole-based compound or an amine-based compound (hindered amine-based compound). Examples of the benzotriazole-based compounds include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, ester compounds of benzenepropanoic acid and 3-(2H-benzotriazol-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-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert- 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-tetramethyl-2-phenylethyl)phenol 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole, 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol], and the like. Examples of the amine compound include bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate, 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 products of 1,2,2,6,6-pentamethyl-4-piperidiol with β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, 2,2,6,6-tetra Examples include the reaction product of tetramethyl-4-piperidiol with β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-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 a resin composition, the weather resistance of the resin composition is improved, and a non-pneumatic tire using such a resin composition for its frame member can maintain 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.

[0047] The heat-resistant anti-aging agent is an additive that has the effect of improving the heat resistance of the resin composition, and the heat-resistant anti-aging agent is preferably a phenolic compound (hindered phenolic compound). 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 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, N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], and the like. Adding a heat-resistant anti-aging agent to a resin composition improves the heat resistance of the resin composition, and a non-pneumatic tire using such a resin composition for its frame member can maintain 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.

[0048] The moisture-heat resistant additive is an additive that has the effect of improving the moisture-heat resistance of the resin composition. As the moisture-heat resistant additive, a carbodiimide compound or an epoxy compound is preferred, and an epoxy compound is more preferred. The carbodiimide compound may be any compound having one or more carbodiimide groups in the molecule, and examples thereof 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; bifunctional 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. Of these, polyfunctional carbodiimide compounds are preferred. Here, the term "polyfunctional carbodiimide compound" refers to a compound having two or more carbodiimide groups. Examples of the polyfunctional carbodiimide compound include polyfunctional carbodiimide compounds commonly known under 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 RheinChemie). These carbodiimide compounds may be used singly or in combination. Specific examples of the epoxy compound include epoxidized soybean oil, epoxidized linseed oil, phenyl glycidyl ether, allyl glycidyl ether, tert-butylphenyl glycidyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexylcarboxylate, 2,3-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate, 4-(3,4-epoxymethyl)-2,3-epoxymethyl-3',4'-epoxymethyl ... butyl-3',4'-epoxycyclohexylcarboxylate, 3,4-epoxycyclohexylethylene oxide, cyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-6'-methylcyclohexylcarboxylate, bisphenol A diglycidyl ether, tetrabromobisphenol A glycidyl ether, diglycidyl ester of phthalic acid, diglycidyl ester of hexahydrophthalic acid, bis-epoxydicyclopentadiene ether, bis-epoxyethylene glycol, bis-epoxycyclohexyl adipate, butadiene diepoxide, tetraphenylethylene epoxide, octyl epoxythalate, 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-epoxycyclohexylcarboxylate, 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-epoxytetrahydrophthalic anhydride, 3-tert-butyl-4,Examples of epoxy compounds include 5-epoxytetrahydrophthalic anhydride, diethyl-4,5-epoxy-cis-1,2-cyclohexyldicarboxylate, and di-n-butyl-3-tert-butyl-4,5-epoxy-cis-1,2-cyclohexyldicarboxylate. These epoxy compounds can be used alone or in combination. By adding a moisture-heat resistant additive to a resin composition, the moisture-heat resistance of the resin composition is improved, and a non-pneumatic tire using such a resin composition for its frame member can maintain desired properties over a long period of time. The amount of the moisture-heat resistant 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.

[0049] The flexural modulus at each temperature of the resin composition used for the skeletal member can be adjusted within a desired range by adjusting the types and blending ratios of the resin components used and the types and amounts of the additives added. For example, when a thermoplastic elastomer having hard segments and soft segments in the molecule is used as the resin component of the resin composition, the flexural modulus at each temperature of the resin composition can be increased by selecting one with a high ratio of hard segments in the molecule, while the flexural modulus at each temperature of the resin composition can be decreased by selecting one with a high ratio of soft segments in the molecule. Furthermore, the method for preparing the resin composition is not particularly limited, and the resin components may be mixed and then the additives added, or the resin components and the additives may be mixed at once, or multiple resin components to which additives have already been added may be mixed, or a resin component to which additives have been added may be mixed with a resin component to which no additives have been added. The resin composition can be processed into a frame member of a desired shape using various molding methods, with injection molding being preferred.

[0050] In one embodiment of the present invention, the non-pneumatic tire comprises an inner tube mounted on a wheel, an outer tube surrounding the inner tube from the outside in the tire radial direction, a plurality of connecting members arranged along the tire circumferential direction between the inner tube and the outer tube to connect the two tubes together, and a tread member provided on the outside in the tire radial direction of the outer tube, The inner cylinder, the outer cylinder, and the connecting member, which are the frame members, are made of the resin composition. In this case, a non-pneumatic tire having good ride comfort and excellent durability can be obtained.

[0051] Next, the configuration of a non-pneumatic tire according to one embodiment of the present invention will be described. 1 is an explanatory diagram showing a schematic configuration of a non-pneumatic tire according to one embodiment of the present invention, as viewed from the side of the tire. Note that in each drawing used in the following description, the scale has been changed appropriately so that each component can be shown at a size that allows it to be recognized.

[0052] 1, the non-pneumatic tire 1 of this embodiment includes an inner cylinder 2 that is fitted onto a wheel (not shown), an outer cylinder 3 that surrounds the inner cylinder 2 from the outside in the tire radial direction, and a plurality of elastically deformable connecting members 4 that are arranged along the tire circumferential direction between the inner cylinder 2 and the outer cylinder 3 and 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 peripheral surface of the outer cylinder 3. This non-pneumatic tire 1 is used for wheelchairs (especially electric wheelchairs), bicycles, motorcycles, golf carts, automobiles, etc. (hereinafter, these will be collectively referred to simply as vehicles).

[0053] Here, the inner cylinder 2, the outer cylinder 3, and the tread component 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 seen from the tire width direction, the direction going 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.

[0054] The tire radial diameter D of the non-pneumatic tire 1 of this embodiment is 35 cm or less, preferably 32 cm or less, more preferably 30 cm or less, and also preferably 10 cm or more, more preferably 12 cm or more. A tire with a tire radial diameter D of 35 cm or less is lightweight and suitable, for example, for use as a tire for a wheelchair (especially an electric wheelchair). Furthermore, a tire radial diameter D of 10 cm or more has high durability.

[0055] The non-pneumatic tire 1 of this embodiment is preferably used at a traveling speed of 30 km / h or less, and more preferably at a traveling speed of 15 km / h or less and 5 km / h or more. The non-pneumatic tire 1 of this embodiment has good ride comfort and durability even when used at a traveling speed of 30 km / h or less. Furthermore, the non-pneumatic tire 1 that has good ride comfort and durability when used at a traveling speed of 30 km / h or less is suitable, for example, as a tire for a wheelchair (especially an electric wheelchair).

[0056] The inner cylinder 2 is attached to the vehicle axle (not shown) via a wheel. Metallic materials such as aluminum, aluminum alloy, and steel can be used as materials for the wheel and axle. The central axes of the inner cylinder 2 and the outer cylinder 3 are arranged coaxially with the central axis O. The inner cylinder 2, the outer cylinder 3, and the connecting member 4 are arranged in the tire width direction with their respective central portions in the tire width direction aligned with each other.

[0057] In this embodiment, the inner cylinder 2, the outer cylinder 3, and the connecting member 4 are integrally formed from a resin composition, which allows the inner cylinder 2, the outer cylinder 3, and the connecting member 4 to be molded by injection molding, making them suitable for mass production. The inner cylinder 2, the outer cylinder 3, and the connecting member 4 may be formed as separate bodies.

[0058] The tread component 5 is formed of, for example, vulcanized rubber obtained by vulcanizing a rubber composition containing natural rubber or the like, or a thermoplastic material. Examples of thermoplastic materials include thermoplastic resins such as polyurethane resin, polyolefin resin, polyvinyl chloride resin, and polyamide resin. From the viewpoint of abrasion resistance, it is preferable to form the tread component 5 from vulcanized rubber. In this embodiment, an adhesive layer (not shown) is provided between the outer tube 3 and the tread component 5 to bond the outer tube 3 and the tread component 5 together. A commercially available adhesive can be used for the adhesive layer. For example, a cyanoacrylate adhesive or an epoxy adhesive can be used, and a specific example is Aron Alpha EXTRA 2000 (manufactured by Toa Gosei Co., Ltd.), but the adhesive is not limited thereto.

[0059] The connecting member 4 is formed as a curved rectangular plate overall, with the front and back surfaces facing the tire circumferential direction and the side surfaces facing the tire width direction. The connecting member 4 is made of an elastically deformable material and connects the outer peripheral surface side of the inner cylinder 2 and the inner peripheral surface side of the outer cylinder 3 so as to be elastically deformable relative to each other. A plurality of connecting members 4 are arranged at equal intervals in the tire circumferential direction. In Fig. 1, there are 30 connecting members 4, but the number of connecting members 4 in the non-pneumatic tire of the present invention is not limited to this.

[0060] 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 in the tire radial direction of the connecting member 4. When the vehicle is running, the connecting member 4 elastically deforms due to the load, absorbing vibrations transmitted from the ground to the vehicle.

[0061] In the non-pneumatic tire according to this embodiment, the framework members correspond to the inner tube 2, outer tube 3, and connecting member 4 of the non-pneumatic tire 1, and the inner tube 2, outer tube 3, and connecting member 4 are made of the above-mentioned resin composition, i.e., a resin composition having a flexural modulus of 247 MPa or less at -20°C in accordance with ISO178 and a flexural modulus of 32 MPa or more at 60°C in accordance with ISO178. As described above, when the vehicle is running, the connecting members 4 elastically deform due to the load and absorb vibrations transmitted from the ground to the vehicle, but at this time, adjacent connecting members 4 may rub against each other. The resin composition described above (i.e., a resin composition having a flexural modulus of elasticity of 247 MPa or less at -20°C in accordance with ISO178 and a flexural modulus of elasticity of 32 MPa or more at 60°C in accordance with ISO178) can prevent adjacent connecting members 4 from rubbing against each other, thereby preventing them from breaking, and as a result, the durability of the non-pneumatic tire 1 can be improved. Therefore, by forming the inner tube 2, the outer tube 3, and the connecting member 4, which serve as skeletal members, from the above-described resin composition, it is possible to provide a non-pneumatic tire that combines ride comfort and durability over a wide temperature range, even if the tire has a small diameter D of 35 cm or less.

[0062] In addition, in the non-pneumatic tire 1 according to this embodiment, the inner tube 2, the outer tube 3, and the connecting member 4 must be made of the above-mentioned resin composition, but different resin compositions may be used for the inner tube 2, the outer tube 3, and the connecting member 4 that constitute the framework member. [Example]

[0063] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0064] (Examples 1 to 6 and Comparative Examples 1 to 2) The flexural modulus of the resin compositions shown in Table 1 was measured by the following method.

[0065] <Flexural modulus> The flexural modulus of the resin compositions other than that of Example 1 was measured at -20°C, 0°C, 23°C, 40°C, and 60°C by a three-point bending test in accordance with ISO 178. Note that the flexural modulus of Example 1 was estimated from the results of Comparative Examples 1 and 2 and Examples 2 to 6 and the resin composition.

[0066] Next, sample non-pneumatic tires were produced using the resin compositions shown in Examples 2 and 5. Each sample non-pneumatic tire had a tire radial diameter D (outer diameter of tread component 5) of 23.4 cm, an outer diameter of outer cylinder 2 of 23.0 cm, an inner diameter of inner cylinder 3 of 14.9 cm, and a width in the tire width direction (width of outer cylinder 2, inner cylinder 3, and connecting component 4) of 5.6 cm, and the structure of these non-pneumatic tire samples conformed to the schematic diagram shown in FIG. The non-pneumatic tires of each sample were similar in other components, except for the materials constituting the inner cylinder 2, outer cylinder 3, and connecting member 4. The types and contents of the resin compositions constituting the inner cylinder 2, outer cylinder 3, and connecting member 4 are as shown in Table 1. For each of the produced sample non-pneumatic tires, the initial durability and ride comfort were evaluated or predicted by the following methods.

[0067] <Evaluation method for initial durability> For each sample tire of Example 2 and Example 5, a 10 mm wide, 5 mm high protrusion was attached to a drum durability tester, and the tire was run at 15 km / h under a constant load at 20°C, and the running distance until failure was measured to evaluate initial durability. For Comparative Examples 1 and 2 and Examples 1, 3, 4, and 6, the initial durability of a non-pneumatic tire of a similar structure was predicted based on the flexural modulus of each resin shown in Table 1 and the evaluation of the non-pneumatic tires produced in Examples 2 and 5. The results were classified according to the following criteria. The evaluation criteria are shown below. If the mileage is 5000km or more: Yes If the mileage is less than 5000km: × In addition, for Comparative Example 2, contact between the spokes was predicted from the flexural modulus and the distance between the spokes for each load, and it was evaluated as spoke contact.

[0068] <Ride comfort evaluation method> The sample tire of Example 5 was mounted on a vehicle, and the vehicle was driven at 10 km / h on a dry road surface in environments of 8 to 9°C and 25 to 30°C, and the ride comfort was evaluated based on the vibration values ​​measured. For Example 2, a tire having the same structure as Example 5 was mounted on a vehicle, and the vehicle was driven at 10 km / h on a dry road surface in an environment of 25 to 30°C, and the ride comfort was evaluated based on the vibration values ​​measured. The vibration values ​​were measured by placing an accelerometer at the feet of the occupant in the vehicle, measuring the vibration when the vehicle was driven on an asphalt-paved road, squaring the vibration amplitude to make it a positive value, and then averaging and taking the square root (RMS value) and recording it. The ride comfort of Comparative Examples 1 and 2 and Examples 1, 2, 3, 4, and 6 in an environment of 8 to 9°C was evaluated based on vibration values ​​predicted by a linear equation using the flexural modulus at 9°C predicted from the measured vibration values ​​of the non-pneumatic tire produced in Example 5 and the flexural modulus listed in Table 1, and the rate of change in flexural modulus and vibration value calculated from the flexural modulus at 27°C predicted from the measured vibration values ​​of the non-pneumatic tires produced in Examples 2 and 5 at 25 to 30°C and the flexural modulus listed in Table 1. Regarding the ride comfort of Comparative Example 1 and Examples 1, 3, 4, and 6 in an environment of 25 to 30°C, the ride comfort of a non-pneumatic tire of a similar structure was predicted based on the flexural modulus of each resin listed in Table 1 and the evaluation of the non-pneumatic tires produced in Examples 2 and 5. Table 1 shows indexes for each, with Comparative Example 1 set to 100. The smaller the index, the better. For Comparative Example 2, contact between the spokes was predicted from the flexural modulus and the distance between the spokes for each load, and therefore vibration values ​​were not measured.

[0069] [Table 1]

[0070] *1 TPC-1: Polyester-based thermoplastic elastomer with polybutylene terephthalate hard segments, manufactured by Toyobo Co., Ltd., product name "Pelprene P150B" *2 TPC-2: Polyester-based thermoplastic elastomer with hard segments of polybutylene terephthalate, manufactured by Toyobo Co., Ltd., product name "Pelprene P90B" *3 TPC-3: A polyester-based thermoplastic elastomer whose hard segment is polybutylene terephthalate, with a flexural modulus equivalent to that of Toyobo's "Pelprene P90B" product. *4 TPC-4: A polyester-based thermoplastic elastomer whose hard segment is polybutylene terephthalate, with a flexural modulus equivalent to that of Toyobo's "Pelprene P70B" product. *5 TPC-5: A polyester-based thermoplastic elastomer whose hard segment is polybutylene terephthalate, with a flexural modulus equivalent to that of Toyobo's "Pelprene P46D01" product. *6 TPC-6: A polyester-based thermoplastic elastomer whose hard segment is polybutylene terephthalate, with a flexural modulus equivalent to that of Toyobo's "Pelprene P40B" product.

[0071] It can be seen from Table 1 that the tires of the examples according to the present invention have high durability and excellent ride comfort. On the other hand, it can be seen from Comparative Example 1 that when the flexural modulus at −20° C. of the resin composition used for the frame member exceeds 247 MPa, the frame member becomes too hard, resulting in a deterioration in ride comfort. Furthermore, it can be seen from Comparative Example 2 that when the flexural modulus at 60° C. of the resin composition used for the frame member is less than 32 MPa, the ride comfort and initial durability deteriorate. [Explanation of symbols]

[0072] 1: non-pneumatic tire, 2: inner cylinder, 3: outer cylinder, 4: connecting member, 4a: inner portion, 4b: outer portion, 5: tread member, O: center axis, D: tire radial diameter

Claims

1. A non-pneumatic tire using a resin composition for a frame member, The resin composition has a flexural modulus at −20° C. in accordance with ISO 178 of 170 MPa or less, and a flexural modulus at 60° C. in accordance with ISO 178 of 32 MPa or more and 90 MPa or less, A non-pneumatic tire having a radial diameter of 35 cm or less.

2. The non-pneumatic tire according to claim 1 , wherein the resin composition contains a thermoplastic elastomer having hard segments and soft segments in the molecule.

3. The non-pneumatic tire according to claim 2 , wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.

4. The non-pneumatic tire according to claim 3 , wherein the hard segment of the polyester-based thermoplastic elastomer is polybutylene terephthalate.

5. A non-pneumatic tire comprising: an inner tube mounted on a wheel; an outer tube surrounding the inner tube from the outside in the tire radial direction; a plurality of connecting members arranged along the tire circumferential direction between the inner tube and the outer tube to connect the two tubes; and a tread member provided on the outside in the tire radial direction of the outer tube, The non-pneumatic tire according to any one of claims 1 to 4, wherein the inner tube, the outer tube, and the connecting member as the frame members are made of the resin composition.

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