Method for manufacturing a tire and a tire carcass

Abstract

To provide a tire including a tire skeleton that is made of a thermoplastic resin material and has excellent durability, and to provide a method for manufacturing a tire skeleton.SOLUTION: A tire includes: a tire skeleton formed of a resin material including a thermoplastic elastomer, where the thermoplastic elastomer has a long cycle L of 17.5 nm or more that is measured by a small angle X-ray scattering method.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a tire and a tire carcass.

Background Art

[0002] In pneumatic tires used for vehicles such as passenger cars, tires using thermoplastic resin materials, particularly thermoplastic resins and thermoplastic elastomers, have been studied for reasons such as weight reduction, ease of molding, and ease of recycling. Thermoplastic resin materials have many advantages from the viewpoint of improving productivity, such as being capable of injection molding.

[0003] As a tire using a thermoplastic resin material, for example, Patent Document 1 describes a tire having a tire carcass formed using a polyamide-based thermoplastic elastomer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When applying a thermoplastic resin material to a tire, the resin material is required to have durability sufficient to withstand the load applied to the tire during vehicle driving and stopping. However, there is still room for development in resin materials that can satisfy the desired durability.

[0006] In view of the above circumstances, an object of the present disclosure is to provide a tire including a tire carcass made of a thermoplastic resin material and having excellent durability, and a method for manufacturing the tire carcass.

Means for Solving the Problems

[0007] The above problems are solved by the following disclosure. <1>A tire having a tire carcass formed of a resin material containing a thermoplastic elastomer, wherein a long period L measured by a small-angle X-ray scattering method of the thermoplastic elastomer is 17.5 nm or more. <2>The tire according to <1>, wherein a crystal melting point Tm measured by a differential scanning calorimeter of the thermoplastic elastomer is 205 °C or more. <3>The tire according to <1> or <2>, wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer. <4>The tire according to any one of <1> to <3>, wherein a tensile elastic modulus of the resin material is 230 MPa or more. <5>The tire according to any one of <1> to <4>, wherein a tensile yield stress of the resin material is 16 MPa or more. <6>A method for manufacturing a tire carcass, comprising a step of melting a resin material containing a thermoplastic elastomer and a step of solidifying the resin material, and satisfying at least one of the following (1) and (2). (1) The melting is performed at a temperature A (°C) satisfying the following formula. Melting point of thermoplastic elastomer ≤ A ≤ Melting point of thermoplastic elastomer + 20 °C (2) The solidification is performed at a temperature B (°C) satisfying the following formula. Crystallization start temperature of thermoplastic elastomer - 20 °C ≤ B ≤ Crystallization start temperature of thermoplastic elastomer <7>The method for manufacturing a tire carcass according to <6>, further satisfying the following (3). (3) The resin material is held at a temperature C (°C) satisfying the following formula between the melting and the solidification. Crystallization start temperature of thermoplastic elastomer < C < Melting point of thermoplastic elastomer <8>The method for manufacturing a tire carcass according to <6> or <7>, wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.

Advantages of the Invention

[0008] According to the present disclosure, there are provided a tire including a tire carcass made of a thermoplastic resin material and having excellent durability, and a method for manufacturing the tire carcass.

Brief Description of the Drawings

[0009]

Figure 1A

Figure 1B

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] Hereinafter, specific embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0011] In this specification, "resin" is a concept including thermoplastic resins, thermoplastic elastomers, and thermosetting resins, and does not include vulcanized rubber. Further, in the following description of resins, "resins of the same kind" means a relationship between resins having a common backbone structure, such as ester-based resins or styrene-based resins. In this specification, "thermoplastic elastomer" means a polymer compound composed of a copolymer having a crystalline and high melting point hard segment or a hard segment having a high cohesive force, and a non-crystalline and low glass transition temperature soft segment. Note that a thermoplastic elastomer softens and flows as the temperature rises, and becomes relatively hard and strong when cooled. Further, a thermoplastic elastomer is a polymer compound having rubber-like elasticity. In this specification, the "hard segment" refers to a component that is relatively harder than the soft segment, and the "soft segment" refers to a component that is relatively softer than the hard segment. Note that the hard segment is preferably a molecular constraint component that serves as a crosslinking point of a crosslinked rubber that prevents plastic deformation. Also, the soft segment is preferably a flexible component that exhibits rubber elasticity. In this specification, the numerical range represented by using "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In this specification, the term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as its purpose is achieved.

[0012] <Tire> The tire according to the present disclosure has a tire carcass formed of a resin material containing a thermoplastic elastomer (that is, partially or entirely formed of only the resin material). And the value of the long period L measured by the small angle X-ray scattering method (Small Angle X-ray Xcattering: SAXS) of the thermoplastic elastomer is 17.5 nm or more.

[0013] As a result of the study by the present inventors, it has been clarified that a tire having a tire carcass formed using a thermoplastic elastomer with a long period L value of 17.5 nm or more measured by the small angle X-ray scattering method is superior in durability compared to a tire having a tire carcass that does not satisfy this condition. The reason is presumably as follows, for example. The value of the long period L of the thermoplastic elastomer is the total value of the thickness of the crystalline part and the thickness of the amorphous part in a repeating unit composed of one crystalline part and one amorphous part in the repeating structure of the crystalline part and the amorphous part of the hard segment in the molecule of the thermoplastic elastomer. A thermoplastic elastomer showing a large value of the long period L of 17.5 nm or more has a large tensile yield stress. Therefore, it is considered that the durability of the tire carcass obtained using a resin material containing a thermoplastic elastomer is improved.

[0014] (Long period L) For the tire according to the present disclosure, the long period L measured by the small-angle X-ray scattering method of the thermoplastic elastomer contained in the tire skeleton is 17.5 nm or more. From the viewpoint of the durability of the tire skeleton, the long period L is preferably 20.0 nm or more, more preferably 25.0 nm or more, and even more preferably 30.0 nm or more. The upper limit value of the long period L is not particularly limited, and it may be 60.0 nm or less, 50.0 nm or less, or 40.0 nm or less.

[0015] In this specification, the long period L of the thermoplastic elastomer is calculated as follows by the small-angle X-ray scattering method using a sample collected from the tire skeleton or a sample prepared from the resin material used for forming the tire skeleton. Regarding the scattering angle θ measured in small-angle X-ray scattering, it is converted into the scattering vector q using Equation (a). A graph of the scattering intensity I(q) with respect to the scattering vector q is created, and the long period L is obtained from Equation (b) using the value of q at the primary peak thereof. Equation (a) q = (4πsinθ) / λ Equation (b) L = 2π / q max

[0016] The value of the long period L tends to increase as the growth of crystals in the thermoplastic elastomer is promoted and the thickness of the crystalline part of the hard segment increases. Note that as the long period L increases, the melting point of the thermoplastic elastomer tends to increase.

[0017] The method for controlling the value of the long period L of the thermoplastic elastomer is not particularly limited. For example, by raising the cooling temperature (e.g., mold temperature) during the formation of the tire skeleton to reduce the cooling rate and promoting the growth of crystals, the long period L can be increased. On the other hand, by lowering the cooling temperature during the formation of the tire skeleton to increase the cooling rate and suppressing the growth of crystals, the long period L can be decreased.

[0018] As a method for making the value of the long period L of the thermoplastic elastomer 17.5 nm or more, a method of controlling the molding conditions of the thermoplastic elastomer as described in the method for manufacturing a tire skeleton body described later can be mentioned.

[0019] (Crystalline melting point Tm) From the viewpoint of durability, it is preferable that the crystalline melting point Tm measured by a differential scanning calorimeter of the thermoplastic elastomer is 205°C or more.

[0020] In this specification, the crystalline melting point Tm of the thermoplastic elastomer indicates the melting point of the crystal formed by the hard segment of the thermoplastic elastomer. The larger the value of the crystalline melting point Tm, the thicker the thickness of the crystal structure. In this specification, the crystalline melting point Tm is determined by the temperature of the melting peak observed at a heating rate of 10°C / min by a differential scanning calorimeter after conditioning a sample collected from the tire skeleton body or a sample made from the resin material used for forming the tire skeleton body in an environment of 23°C and 50% RH for 1 day or more.

[0021] When the crystalline melting point Tm is 205°C or more, the durability of the tire, particularly the crack resistance against impact, is improved. This is presumably because when the crystalline melting point Tm is 205°C or more, the strength of the crystal structure improves as the crystal thickness increases.

[0022] More preferably, the crystalline melting point Tm is 205.5°C or more, and even more preferably 206°C or more. The upper limit value of the crystalline melting point Tm is not particularly limited, but it may be 210°C or less, 208°C or less, or 207°C or less.

[0023] The method for controlling the value of the crystalline melting point Tm of the thermoplastic elastomer is not particularly limited. For example, by raising the cooling temperature (e.g., mold temperature) during the formation of the tire skeleton body to reduce the cooling rate and promoting the growth of crystals, the crystalline melting point Tm can be increased. On the other hand, by lowering the cooling temperature during the formation of the tire skeleton body to increase the cooling rate and suppressing the growth of crystals, the crystalline melting point Tm can be decreased.

[0024] (Tensile modulus of elasticity) From the perspective of durability, it is preferable that the tensile modulus of elasticity measured by the static tensile test of the resin material is 230 MPa or more.

[0025] In this specification, the tensile modulus of elasticity of the resin material indicates the slope at 1% - 2% strain in the tensile test of the resin material. The larger the value of the tensile modulus of elasticity, the more it means that deformation can be suppressed against the load. In this specification, the tensile modulus of elasticity is for a sample taken from the tire carcass or a sample made from the resin material used for forming the tire carcass. After conditioning in an environment of 23°C and 50% RH for 1 day or more, it is determined by the slope observed under the conditions of a static tensile test specified in JIS K7113 (1995) with a strain rate of 0.05 s -1 determined by the slope observed under the condition of.

[0026] When the tensile modulus of elasticity is 230 MPa or more, the durability of the tire, particularly the crack resistance against impact, is improved. This is presumably because when the tensile modulus of elasticity is 230 MPa or more, the plastic deformation of the resin material is suppressed.

[0027] More preferably, the tensile modulus of elasticity is 250 MPa or more, and even more preferably 270 MPa or more. The upper limit value of the tensile modulus of elasticity is not particularly limited, and it may be 400 MPa or less, 380 MPa or less, or 350 MPa or less.

[0028] The method for controlling the value of the tensile modulus of elasticity of the resin material is not particularly limited. For example, by raising the cooling temperature (e.g., mold temperature) during the formation of the tire carcass to reduce the cooling rate and promoting the growth of crystals, the tensile modulus of elasticity can be increased. On the other hand, by lowering the cooling temperature during the formation of the tire carcass to increase the cooling rate and suppressing the growth of crystals, the tensile modulus of elasticity can be decreased.

[0029] (Tensile yield stress) From the perspective of durability, it is preferable that the tensile yield stress measured by the static tensile test of the resin material is 16 MPa or more.

[0030] In this specification, the tensile yield stress of the resin material indicates the stress value at the yield point of the resin material. The larger the value of the tensile yield stress, the more difficult it is for the crystal structure of the resin material to collapse. In this specification, the tensile yield stress is for a sample taken from the tire carcass or a sample made from the resin material used to form the tire carcass. After conditioning in an environment of 23°C and 50% RH for one day or more, it is determined from the stress value at the yield point observed in the static tensile test specified in JIS K7113 (1995) under the condition of a strain rate of 0.05 s -1 and determined from the stress value at the yield point observed under the condition of.

[0031] When the tensile yield stress is 16 MPa or more, the durability of the tire, particularly the crack resistance to impact, is improved. This is presumably because when the yield stress is 16 MPa or more, the plastic deformation of the resin material is suppressed.

[0032] It is more preferable that the tensile yield stress is 16.5 MPa or more, and further preferably 17 MPa or more. The upper limit value of the tensile yield stress is not particularly limited, and it may be 25 MPa or less, 23 MPa or less, or 20 MPa or less.

[0033] The method for controlling the value of the tensile yield stress of the resin material is not particularly limited. For example, by raising the cooling temperature (e.g., mold temperature) during the formation of the tire carcass to lower the cooling rate and promoting crystal growth, the tensile yield stress can be increased. On the other hand, by lowering the cooling temperature during the formation of the tire carcass to increase the cooling rate and suppressing crystal growth, the tensile yield stress can be decreased.

[0034] [Resin material] The resin material includes a thermoplastic elastomer, and may also contain components other than the thermoplastic elastomer such as additives, if desired. The type of thermoplastic elastomer used for forming the tire carcass is not particularly limited. For example, polyester-based thermoplastic elastomers (TPC), polyamide-based thermoplastic elastomers (TPA), polystyrene-based thermoplastic elastomers (TPS), polyurethane-based thermoplastic elastomers (TPU), olefin-based thermoplastic elastomers (TPO), crosslinked thermoplastic rubbers (TPV), and other thermoplastic elastomers (TPZ), etc. can be mentioned. Regarding the definition and classification of thermoplastic elastomers, JIS K6418 can be referred to.

[0035] From the viewpoint of the durability of the tire, a polyester-based thermoplastic elastomer is preferred as the thermoplastic elastomer. A tire containing a polyester-based thermoplastic elastomer exhibits high durability with the generation and growth of cracks caused by repeatedly applied loads being suppressed.

[0036] - Polyester-based thermoplastic elastomer - A polyester-based thermoplastic elastomer is a polymer compound having elasticity and is a thermoplastic resin material composed of a copolymer having a polymer containing a polyester that forms a hard segment with high crystallinity and a high melting point, and a polymer that forms a soft segment with low glass transition temperature and is amorphous. And a polyester-based thermoplastic elastomer means one having a partial structure made of polyester in its structure. Examples of the polyester-based thermoplastic elastomer include, for example, ester-based thermoplastic elastomers (TPC) defined in JIS K6418:2007. Examples of the polyester-based thermoplastic elastomer include materials in which at least polyester forms a hard segment with high crystallinity and a high melting point, and other polymers (for example, polyester or polyether, etc.) form a soft segment with low glass transition temperature and are amorphous.

[0037] As the polyester for forming the hard segment, for example, an aromatic polyester can be used. The aromatic polyester can be formed from, for example, an aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol.

[0038] Examples of the aromatic polyester include polybutylene terephthalate derived from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol. Further, dicarboxylic acid components such as isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethane dicarboxylic acid, 5-sulfoisophthalic acid, or their ester-forming derivatives, and diol components such as diols having a molecular weight of 300 or less (for example, aliphatic diols such as ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, and decamethylene glycol, alicyclic diols such as 1,4-cyclohexanedimethanol and tricyclodecane dimethylol, and aromatic diols 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, and 4,4'-dihydroxy-p-quarterphenyl), and polyesters derived from these may also be used. Alternatively, a copolyester in which two or more of these dicarboxylic acid components and diol components are used in combination may be used. It is also possible to copolymerize polyfunctional carboxylic acid components, polyfunctional oxyacid components, polyfunctional hydroxy components, etc. having three or more functions in the range of 5 mol% or less. Examples of the polyester for forming the hard segment include polyethylene terephthalate, polybutylene terephthalate, polymethylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate. Among them, polybutylene terephthalate is preferable.

[0039] Examples of the polymer that forms the soft segment include, for example, aliphatic polyesters 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 adduct of poly(propylene oxide) glycol, and a copolymer of ethylene oxide and tetrahydrofuran. Examples of the aliphatic polyester include poly(ε-caprolactone), poly(enantholactone), polycapryllactone, polybutylene adipate, and polyethylene adipate.

[0040] Among these aliphatic polyethers and aliphatic polyesters, from the viewpoint of the elastic properties of the obtained polyester block copolymer, examples of the polymer that forms the soft segment preferably include poly(tetramethylene oxide) glycol, an ethylene oxide adduct of poly(propylene oxide) glycol, poly(ε-caprolactone), polybutylene adipate, and polyethylene adipate.

[0041] From the viewpoints of toughness and low-temperature flexibility, the number-average molecular weight of the polymer (i.e., polyester) that forms the hard segment is preferably 300 to 6000. From the viewpoints of toughness and low-temperature flexibility, the number-average molecular weight of the polymer that forms the soft segment is preferably 300 to 6000. Furthermore, from the viewpoint of the moldability of the tire carcass, the mass ratio (x:y) of the hard segment (x) to the soft segment (y) is preferably 99:1 to 20:80, and more preferably 98:2 to 30:70.

[0042] As combinations of the above-mentioned hard segments and soft segments, for example, each combination of the hard segments and soft segments mentioned above can be cited. Among these, as the combination of the above-mentioned hard segments and soft segments, a combination in which the hard segment is polybutylene terephthalate and the soft segment is an aliphatic polyether is preferable, and a combination in which the hard segment is polybutylene terephthalate and the soft segment is poly(ethylene oxide) glycol is more preferable.

[0043] As commercially available products of polyester-based thermoplastic elastomers, for example, "Hytrel" series (such as 3046, 5557, 6347, 4047N, and 4767N, etc.) manufactured by Toray DuPont Co., Ltd., "Pelprene" series (such as P30B, P40B, P40H, P55B, P70B, P150B, P280B, E450B, P150M, S1001, S2001, S5001, S6001, and S9001, etc.) manufactured by Toyobo Co., Ltd. can be used.

[0044] 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.

[0045] In addition, when the polyester-based thermoplastic elastomer is contained in the resin material in the present embodiment, the content of the polyester-based thermoplastic elastomer in all the contained thermoplastic elastomers is not particularly limited, but is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more based on the total amount of all the resins. When the content of the polyester-based thermoplastic elastomer is 50% by mass or more based on the total amount of the thermoplastic elastomers, the characteristics of the polyester-based thermoplastic elastomer can be sufficiently exhibited, and it is easier to improve the durability of the tire.

[0046] -Polyamide-based thermoplastic elastomer- A polyamide-based thermoplastic elastomer is a thermoplastic resin material composed of a copolymer having a polymer that forms a hard segment with high crystallinity and a high melting point and a polymer that forms a soft segment with low crystallinity and a low glass transition temperature, and means a polymer having an amide bond (-CONH-) in the main chain of the polymer that forms the hard segment. Examples of the polyamide-based thermoplastic elastomer include materials in which at least polyamide forms a hard segment with high crystallinity and a high melting point, and other polymers (e.g., polyester or polyether, etc.) form a soft segment with low crystallinity and a low glass transition temperature. Further, the polyamide-based thermoplastic elastomer may be formed using a chain extender such as dicarboxylic acid in addition to the hard segment and the soft segment. Specific examples of the polyamide-based thermoplastic elastomer include amide-based thermoplastic elastomers (TPA) defined in JIS K6418:2007, polyamide-based elastomers described in JP-A No. 2004-346273, and the like.

[0047] In the polyamide-based thermoplastic elastomer, examples of the polyamide that forms the hard segment include polyamides produced from monomers represented by the following general formula (1) or general formula (2).

[0048] [Chemical formula] General formula (1)

[0049] [In general formula (1), R 1 represents a hydrocarbon molecular chain having 2 to 20 carbon atoms (e.g., an alkylene group having 2 to 20 carbon atoms).]

[0050] [Chemical formula] General formula (2)

[0051] [In General Formula (2), R 2 represents a hydrocarbon molecular chain having 3 to 20 carbon atoms (for example, an alkylene group having 3 to 20 carbon atoms).]

[0052] In General Formula (1), R 1 is preferably a hydrocarbon molecular chain having 3 to 18 carbon atoms (for example, an alkylene group having 3 to 18 carbon atoms), more preferably a hydrocarbon molecular chain having 4 to 15 carbon atoms (for example, an alkylene group having 4 to 15 carbon atoms), and particularly preferably a hydrocarbon molecular chain having 10 to 15 carbon atoms (for example, an alkylene group having 10 to 15 carbon atoms). Further, in General Formula (2), R 2 is preferably a hydrocarbon molecular chain having 3 to 18 carbon atoms (for example, an alkylene group having 3 to 18 carbon atoms), more preferably a hydrocarbon molecular chain having 4 to 15 carbon atoms (for example, an alkylene group having 4 to 15 carbon atoms), and particularly preferably a hydrocarbon molecular chain having 10 to 15 carbon atoms (for example, an alkylene group having 10 to 15 carbon atoms). Examples of the monomer represented by General Formula (1) or General Formula (2) include ω-aminocarboxylic acid or lactam. Further, examples of the polyamide forming the hard segment include polycondensates of these ω-aminocarboxylic acids or lactams, and co-condensation polymers of diamine and dicarboxylic acid, etc.

[0053] Examples of ω-aminocarboxylic acid include aliphatic ω-aminocarboxylic acids having 5 to 20 carbon atoms such as 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 10-aminocapric acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Examples of lactam include aliphatic lactams having 5 to 20 carbon atoms such as lauryllactam, ε-caprolactam, undecanelactam, ω-enanthlactam, and 2-pyrrolidone. Examples of the diamine include diamine compounds such as aliphatic diamines having 2 to 20 carbon atoms, such as ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, and metaxylylenediamine. Further, the dicarboxylic acid can be represented by HOOC-(R 3 ) m -COOH (R 3 : molecular chain of a hydrocarbon having 3 to 20 carbon atoms, m: 0 or 1), and examples thereof include aliphatic dicarboxylic acids having 2 to 20 carbon atoms, such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. As the polyamide forming the hard segment, a polyamide obtained by ring-opening polycondensation of lauryllactam, ε-caprolactam, or undecanolactam can be preferably used.

[0054] Examples of the polymer forming the soft segment include, for example, polyester and polyether. Specifically, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and ABA type triblock polyether can be mentioned. These can be used alone or in combination of two or more. Also, polyether diamine obtained by reacting ammonia or the like at the terminal of the polyether can also be used. Here, the "ABA type triblock polyether" means a polyether represented by the following general formula (3).

[0055]

Chemical formula

[0056] [In General Formula (3), x and z represent integers from 1 to 20. y represents an integer from 4 to 50.]

[0057] In General Formula (3), x and z are each preferably an integer from 1 to 18, more preferably an integer from 1 to 16, still more preferably an integer from 1 to 14, and particularly preferably an integer from 1 to 12. Also, in General Formula (3), y is preferably an integer from 5 to 45, more preferably an integer from 6 to 40, still more preferably an integer from 7 to 35, and particularly preferably an integer from 8 to 30.

[0058] Examples of the combination of the hard segment and the soft segment include each of the combinations of the hard segment and the soft segment mentioned above. Among these, as the combination of the hard segment and the soft segment, a combination of a ring-opening polycondensate of lauryllactam and polyethylene glycol, a combination of a ring-opening polycondensate of lauryllactam and polypropylene glycol, a combination of a ring-opening polycondensate of lauryllactam and polytetramethylene ether glycol, or a combination of a ring-opening polycondensate of lauryllactam and an ABA-type triblock polyether is preferable, and a combination of a ring-opening polycondensate of lauryllactam and an ABA-type triblock polyether is more preferable.

[0059] From the viewpoint of melt moldability, the number average molecular weight of the polymer (i.e., polyamide) forming the hard segment is preferably 300 to 15000. Also, from the viewpoints of toughness and low-temperature flexibility, the number average molecular weight of the polymer forming the soft segment is preferably 200 to 6000. Further, from the viewpoint of the moldability of the tire carcass, the mass ratio (x:y) of the hard segment (x) and the soft segment (y) is preferably 50:50 to 90:10, and more preferably 50:50 to 80:20.

[0060] The polyamide-based thermoplastic elastomer can be synthesized by copolymerizing a polymer forming the hard segment and a polymer forming the soft segment by a known method.

[0061] Examples of commercially available polyamide-based thermoplastic elastomers include, for example, the "UBESTA XPA" series of Ube Industries, Ltd. (e.g., XPA9063X1, XPA9055X1, XPA9048X2, XPA9048X1, XPA9040X1, and XPA9040X2XPA9044, etc.), the "BESTAMID" series of Daicel-EPONY Co., Ltd. (e.g., E40-S3, E47-S1, E47-S3, E55-S1, E55-S3, EX9200, and E50-R2, etc.).

[0062] - Polystyrene-based thermoplastic elastomer Examples of polystyrene-based thermoplastic elastomers include materials in which at least polystyrene forms a hard segment and another polymer (e.g., polybutadiene, polyisoprene, polyethylene, hydrogenated polybutadiene, or hydrogenated polyisoprene, etc.) forms an amorphous soft segment with a low glass transition temperature. As the polystyrene forming the hard segment, those obtained by known radical polymerization methods, ionic polymerization methods, etc. are preferably used, and specifically, polystyrene having anionic living polymerization can be mentioned. Also, as the polymer forming the soft segment, for example, polybutadiene, polyisoprene, and poly(2,3-dimethyl-butadiene), etc. can be mentioned.

[0063] Examples of the combination of the hard segment and the soft segment include the respective combinations of the hard segment and the soft segment mentioned above. Among these, as the combination of the hard segment and the soft segment, the combination of polystyrene and polybutadiene, or the combination of polystyrene and polyisoprene is preferable. Also, in order to suppress an unintended crosslinking reaction of the thermoplastic elastomer, the soft segment is preferably hydrogenated.

[0064] The number average molecular weight of the polymer (i.e., polystyrene) forming the hard segment is preferably 5000 to 500000, more preferably 10000 to 200000. In addition, the number average molecular weight of the polymer forming the soft segment is preferably from 5,000 to 1,000,000, more preferably from 10,000 to 800,000, and still more preferably from 30,000 to 500,000. Further, the volume ratio (x:y) of the hard segment (x) and the soft segment (y) is preferably from 5:95 to 80:20, more preferably from 10:90 to 70:30, from the viewpoint of the moldability of the tire carcass.

[0065] The polystyrene-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. Examples of the polystyrene-based thermoplastic elastomer include styrene-butadiene copolymers [e.g., SBS (polystyrene-poly(butylene) block-polystyrene), and SEBS (polystyrene-poly(ethylene / butylene) block-polystyrene)], styrene-isoprene copolymers (e.g., polystyrene-polyisoprene block-polystyrene), styrene-propylene copolymers [e.g., SEP (polystyrene-(ethylene / propylene) block), SEPS (polystyrene-poly(ethylene / propylene) block-polystyrene), SEEPS (polystyrene-poly(ethylene-ethylene / propylene) block-polystyrene), and SEB (polystyrene(ethylene / butylene) block)], and the like.

[0066] Examples of commercially available polystyrene-based thermoplastic elastomers include the "Tuftec" series manufactured by Asahi Kasei Corporation (e.g., H1031, H1041, H1043, H1051, H1052, H1053, H1062, H1082, H1141, H1221, and H1272, etc.), the "SEBS" series (8007, 8076, etc.) and the "SEPS" series (2002, 2063, etc.) manufactured by Kuraray Co., Ltd., and the like can be used.

[0067] - Polyurethane-based thermoplastic elastomer - Examples of polyurethane-based thermoplastic elastomers include materials in which at least polyurethane forms a hard segment that forms a pseudo-crosslink by physical aggregation, and another polymer forms a soft segment that is amorphous and has a low glass transition temperature. Specific examples of polyurethane-based thermoplastic elastomers include polyurethane-based thermoplastic elastomers (TPU) defined in JIS K6418:2007. The polyurethane-based thermoplastic elastomer can be represented as a copolymer containing a soft segment having a unit structure represented by the following formula A and a hard segment having a unit structure represented by the following formula B.

[0068] [Chemical formula]

[0069] [In the formula, P represents a long-chain aliphatic polyether or a long-chain aliphatic polyester. R represents an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon. P’ represents a short-chain aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon.]

[0070] In formula A, as the long-chain aliphatic polyether or long-chain aliphatic polyester represented by P, for example, those having a molecular weight of 500 to 5000 can be used. P is derived from a diol compound containing the long-chain aliphatic polyether or long-chain aliphatic polyester represented by P. Examples of such diol compounds include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, poly(butylene adipate) diol, poly-ε-caprolactone diol, poly(hexamethylene carbonate) diol, and ABA-type triblock polyethers having a molecular weight within the above range. These can be used alone or in combination of two or more.

[0071] In Formula A and Formula B, R is derived from a diisocyanate compound containing an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon represented by R. Examples of the aliphatic diisocyanate compound containing an aliphatic hydrocarbon represented by R include 1,2-ethylene diisocyanate, 1,3-propylene diisocyanate, 1,4-butane diisocyanate, and 1,6-hexamethylene diisocyanate. Examples of the diisocyanate compound containing an alicyclic hydrocarbon represented by R include 1,4-cyclohexane diisocyanate and 4,4-cyclohexane diisocyanate. Further, examples of the aromatic diisocyanate compound containing an aromatic hydrocarbon represented by R include 4,4'-diphenylmethane diisocyanate and tolylene diisocyanate. These can be used alone or in combination of two or more.

[0072] In Formula B, as the short-chain aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon represented by P', those having a molecular weight of less than 500 can be used, for example. Also, P' is derived from a diol compound containing a short-chain aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon represented by P'. Examples of the aliphatic diol compound containing a short-chain aliphatic hydrocarbon represented by P' include glycol and polyalkylene glycol. Specifically, ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol can be mentioned. Examples of the alicyclic diol compound containing an alicyclic hydrocarbon represented by P' include cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, and cyclohexane-1,4-dimethanol. Furthermore, examples of the aromatic diol compound containing an aromatic hydrocarbon represented by P' include hydroquinone, resorcinol, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, bisphenol A, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,2-bis(4-hydroxyphenoxy)ethane, 1,4-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and the like. These can be used alone or in combination of two or more.

[0073] The number average molecular weight of the polymer (i.e., polyurethane) forming the hard segment is preferably 300 to 1500 from the viewpoint of melt moldability. Further, the number average molecular weight of the polymer forming the soft segment is preferably 500 to 20000, more preferably 500 to 5000, and particularly preferably 500 to 3000 from the viewpoints of flexibility and thermal stability of the polyurethane-based thermoplastic elastomer. Further, the mass ratio (x:y) of the hard segment (x) and the soft segment (y) is preferably 15:85 to 90:10, more preferably 30:70 to 90:10 from the viewpoint of moldability of the tire carcass.

[0074] The polyurethane-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. As the polyurethane-based thermoplastic elastomer, for example, the thermoplastic polyurethane described in JP-A-5-331256 can be used. As the polyurethane-based thermoplastic elastomer, specifically, a combination of a hard segment consisting only of an aromatic diol and an aromatic diisocyanate and a soft segment consisting only of a polycarbonate ester is preferable. More specifically, at least one selected from tolylene diisocyanate (TDI) / polyester-based polyol copolymer, TDI / polyether-based polyol copolymer, TDI / caprolactone-based polyol copolymer, TDI / polycarbonate-based polyol copolymer, 4,4'-diphenylmethane diisocyanate (MDI) / polyester-based polyol copolymer, MDI / polyether-based polyol copolymer, MDI / caprolactone-based polyol copolymer, MDI / polycarbonate-based polyol copolymer, and MDI + hydroquinone / polyhexamethylene carbonate copolymer is preferable. Among them, at least one selected from TDI / polyester-based polyol copolymer, TDI / polyether-based polyol copolymer, MDI / polyester polyol copolymer, MDI / polyether-based polyol copolymer, and MDI + hydroquinone / polyhexamethylene carbonate copolymer is more preferable.

[0075] Moreover, as commercially available products of the polyurethane-based thermoplastic elastomer, for example, "Elastollan" series manufactured by BASF (for example, ET680, ET880, ET690, ET890, etc.), "Clamiron U" series manufactured by Kuraray Co., Ltd. (for example, 2000 series, 3000 series, 8000 series, 9000 series, etc.), "Miraclan" series manufactured by Nippon Miraclan Co., Ltd. (for example, XN-2001, XN-2004, P390RSUP, P480RSUI, P26MRNAT, E490, E590, P890, etc.) can be used.

[0076] - Olefin-based thermoplastic elastomer - Examples of olefin-based thermoplastic elastomers include materials in which at least a polyolefin forms a hard segment with a high melting point and crystallinity, and another polymer (e.g., other polyolefins, polyvinyl compounds, etc.) forms a soft segment with a low glass transition temperature and amorphousness. Examples of the polyolefin forming the hard segment include polyethylene, polypropylene, isotactic polypropylene, and polybutene, etc. Examples of olefin-based thermoplastic elastomers include, for example, olefin-α-olefin random copolymers, and olefin block copolymers, etc. Specifically, propylene block copolymers, 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, 1-butene-4-methyl-pentene, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl methacrylate copolymers, ethylene-butyl methacrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers, propylene-methacrylic acid copolymers, propylene-methyl methacrylate copolymers, propylene-ethyl methacrylate copolymers, propylene-butyl methacrylate copolymers, propylene-methyl acrylate copolymers, propylene-ethyl acrylate copolymers, propylene-butyl acrylate copolymers, ethylene-vinyl acetate copolymers, and propylene-vinyl acetate copolymers, etc.

[0077] Among these, as the olefinic thermoplastic elastomer, at least one selected from propylene block copolymers, 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, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl methacrylate copolymers, ethylene-butyl methacrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers, propylene-methacrylic acid copolymers, propylene-methyl methacrylate copolymers, propylene-ethyl methacrylate copolymers, propylene-butyl methacrylate copolymers, propylene-methyl acrylate copolymers, propylene-ethyl acrylate copolymers, propylene-butyl acrylate copolymers, ethylene-vinyl acetate copolymers, and propylene-vinyl acetate copolymers is preferred, and at least one selected from ethylene-propylene copolymers, propylene-1-butene copolymers, ethylene-1-butene copolymers, ethylene-methyl methacrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-ethyl acrylate copolymers, and ethylene-butyl acrylate copolymers is more preferred. Also, two or more olefin resins such as ethylene and propylene may be used in combination. Further, the olefin resin content in the olefinic thermoplastic elastomer is preferably 50% by mass or more and 100% by mass or less.

[0078] The number average molecular weight of the olefinic thermoplastic elastomer is preferably from 5,000 to 10,000,000. When the number average molecular weight of the olefinic thermoplastic elastomer is from 5,000 to 10,000,000, the mechanical properties of the thermoplastic resin material are sufficient and the processability is also excellent. From the same viewpoint, the number average molecular weight of the olefinic thermoplastic elastomer is more preferably from 7,000 to 1,000,000, and particularly preferably from 10,000 to 1,000,000. Thereby, the mechanical properties and processability of the thermoplastic resin material can be further improved. Further, from the viewpoints of toughness and low-temperature flexibility, the number average molecular weight of the polymer forming the soft segment is preferably from 200 to 6,000. Furthermore, from the viewpoint of the moldability of the tire carcass, the mass ratio (x:y) of the hard segment (x) and the soft segment (y) is preferably from 50:50 to 95:15, and more preferably from 50:50 to 90:10. The olefinic thermoplastic elastomer can be synthesized by copolymerization by a known method.

[0079] Further, as the olefinic thermoplastic elastomer, one obtained by acid-modifying the olefinic thermoplastic elastomer may be used. "One obtained by acid-modifying the olefinic thermoplastic elastomer" means bonding an unsaturated compound having an acidic group such as a carboxylic acid group, a sulfuric acid group, and a phosphoric acid group to the olefinic thermoplastic elastomer. As for bonding an unsaturated compound having an acidic group such as a carboxylic acid group, a sulfuric acid group, and a phosphoric acid group to the olefin thermoplastic elastomer, for example, an unsaturated bonding site of an unsaturated carboxylic acid (for example, generally maleic anhydride) as an unsaturated compound having an acidic group is bonded (for example, graft polymerization) to the olefinic thermoplastic elastomer. As the unsaturated compound having an acidic group, from the viewpoint of suppressing the deterioration of the olefinic thermoplastic elastomer, an unsaturated compound having a carboxylic acid group which is a weak acid group is preferable, and examples thereof include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid.

[0080] Examples of commercially available olefin-based thermoplastic elastomers include, for example, the "Tafmer" series manufactured by Mitsui Chemicals, Inc. (e.g., A0550S, A1050S, A4050S, A1070S, A4070S, A35070S, A1085S, A4085S, A7090, A70090, MH7007, MH7010, XM-7070, XM-7080, BL4000, BL2481, BL3110, BL3450, P-0275, P-0375, P-0775, P-0180, P-0280, P-0480, and P-0680, etc.), the "Nuclel" series manufactured by Mitsui DuPont Polychemicals Co., Ltd. (e.g., AN4214C, AN4225C, AN42115C, N0903HC, N0908C, AN42012C, N410, N1050H, N1108C, N1110H, N1207C, N1214, AN4221C, N1525, N1560, N0200H, AN4228C, AN4213C, and N035C, etc.), the "Elvaloy AC" series (e.g., 1125AC, 1209AC, 1218AC, 1609AC, 1820AC, 1913AC, 2112AC, 2116AC, 2615AC, 2715AC, 3117AC, 3427AC, and 3717AC, etc.), the "Acriift" series and the "Evatec" series of Sumitomo Chemical Co., Ltd., the "Ultra-Sen" series manufactured by Tosoh Corporation, the "Prime TPO" series manufactured by Prime Polymer Co., Ltd. (e.g., E-2900H, F-3900H, E-2900, F-3900, J-5900, E-2910, F-3910, J-5910, E-2710, F-3710, J-5910, E-2740, F-3740, R110MP, R110E, T310E, and M142E, etc.), etc. can also be used.

[0081] - Additives - The resin material may, if desired, contain components other than the thermoplastic elastomer. Examples of components other than the thermoplastic elastomer include rubber, thermoplastic resin, fillers (e.g., silica, calcium carbonate, and clay, etc.), anti-aging agents, oil, plasticizers, colorants, and weathering agents, etc.

[0082] It has been found that when a plasticizer is blended with a resin material, the rolling performance of a tire is improved and the injection moldability is also improved. On the other hand, if the blending amount of the plasticizer is too large, it may affect the adhesiveness with other materials due to the occurrence of the bloom and bleed phenomenon. Therefore, it is preferable to select and use a plasticizer having high compatibility with the thermoplastic elastomer to be used, thereby preventing the bloom and bleed phenomenon, improving the rolling performance of the tire, and ensuring moldability and safety.

[0083] When the resin material contains components other than the thermoplastic elastomer, from the viewpoint of sufficiently achieving the effects of the present disclosure, the content of the thermoplastic elastomer in the resin material is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more.

[0084] -Physical properties of resin material- The crystallization start temperature of the thermoplastic elastomer contained in the resin material is preferably in the range of 130°C to 190°C, and more preferably in the range of 150°C to 187°C. When the crystallization start temperature of the thermoplastic elastomer is within the above range, it becomes easier to control the long period L of the thermoplastic elastomer. The crystallization start temperature of the thermoplastic elastomer is measured by differential scanning calorimetry (DSC).

[0085] When the resin material contains two or more thermoplastic elastomers, the crystallization start temperature of the thermoplastic elastomer having the largest content on a mass basis is preferably within the above range. When the resin material contains two or more thermoplastic elastomers, the crystallization start temperature of all the thermoplastic elastomers is preferably within the above range. The melting point (melting point before molding) of the thermoplastic elastomer contained in the resin material is preferably 150°C to 250°C, and more preferably 170°C to 220°C. When the melting point of the thermoplastic elastomer is within the above range, it becomes easier to control the long period L of the thermoplastic elastomer. The melting point of the thermoplastic elastomer is measured by differential scanning calorimetry (DSC).

[0086] When the resin material contains two or more thermoplastic elastomers, it is preferable that the melting point of the thermoplastic elastomer with the highest content by mass is within the above range. When the resin material contains two or more thermoplastic elastomers, it is preferable that the melting points of all the thermoplastic elastomers are within the above range.

[0087] The tensile strength of the resin material (i.e., the tire carcass) itself specified in JIS K7113 (1995) is usually about 15 MPa to 70 MPa, preferably 17 MPa to 60 MPa, and more preferably 20 MPa to 55 MPa.

[0088] The tensile yield elongation of the resin material (i.e., the tire carcass) itself specified in JIS K7113 (1995) is preferably 10% or more, more preferably 10% to 70%, and particularly preferably 15% to 60%. When the tensile yield elongation of the resin material is 10% or more, the elastic region is large and the rim assembly property can be improved.

[0089] The tensile break elongation of the resin material (i.e., the tire carcass) itself specified in JIS K7113 (1995) is preferably 50% or more, more preferably 100% or more, still more preferably 150% or more, and particularly preferably 200% or more. When the tensile break elongation of the resin material is 50% or more, the rim assembly property is good and it can be made difficult to break under collision.

[0090] The heat distortion temperature (condition: at a load of 0.45 MPa) of the resin material (i.e., the tire carcass) itself specified in ISO 75-2 or ASTM D648 is preferably 50°C or more, more preferably 50°C to 150°C, and still more preferably 50°C to 130°C. When the heat distortion temperature of the resin material is 50°C or more, deformation of the tire carcass can be suppressed even when vulcanization is carried out in the manufacture of the tire.

[0091] As the Vicat softening temperature (Method A) defined in JIS K7206 (2016) of the resin material itself (i.e., the tire carcass), 130°C or higher is preferable, 130°C to 250°C is more preferable, and 130°C to 220°C is even more preferable. When the softening temperature (Method A) of the resin material is 130°C or higher, softening and deformation of the tire in the use environment can be suppressed. Also, even when vulcanization is performed during bonding in the manufacture of the tire, deformation of the tire carcass can be suppressed.

[0092] [Constituents other than the tire carcass in the tire] The tire according to the present embodiment may include members other than the tire carcass as necessary. For example, it may include a reinforcing member for reinforcing the tire carcass, which is disposed on the outer periphery or the like of the tire carcass. Examples of the reinforcing member include a cord member formed by including a metal member such as a steel cord, and a member in which the cord member is coated with a coating resin material is also used.

[0093] Examples of the resin used for the coating resin material in the reinforcing member include thermosetting resins, thermoplastic resins, and thermoplastic elastomers. Examples of the thermosetting resin include phenol resin, urea resin, melamine resin, epoxy resin, polyamide resin, and polyester resin. Examples of the thermoplastic resin include urethane resin, olefin resin, vinyl chloride resin, polyamide resin, and polyester resin. Examples of the thermoplastic elastomer include polyester-based thermoplastic elastomer (TPC), polyamide-based thermoplastic elastomer (TPA), polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyurethane-based thermoplastic elastomer (TPU), crosslinked thermoplastic rubber (TPV), or other thermoplastic elastomers (TPZ) defined in JIS K6418:2007. In consideration of the elasticity required during running and the moldability during manufacture, it is preferable to use a thermoplastic elastomer among these. It is also preferable to include a thermoplastic elastomer of the same type as the thermoplastic elastomer contained in the resin material forming the tire carcass.

[0094] Further, a reinforcing member having a structure in which a cord member is coated with a coating resin material via an adhesive (that is, an adhesive layer) may be used, and this reinforcing member may be disposed on the tire carcass. In this case, it is preferable that the Martens hardness (d1) of the tire carcass, the Martens hardness (d2) of the coating resin material, and the Martens hardness (d3) of the adhesive layer satisfy the relationship of d1 ≦ d2 < d3. By setting the Martens hardness of the coating resin material to be smaller than the Martens hardness of the adhesive layer and larger than or equal to the Martens hardness of the tire carcass, the rigidity difference between the resin material forming the tire carcass and the cord member is effectively alleviated. As a result, the durability of the tire can be further improved.

[0095] [Configuration of Tire] Hereinafter, an embodiment of the tire according to the present embodiment will be described with reference to the drawings. Note that members having the same function and action may be given the same reference numerals throughout the drawings, and in that case, the description of the reference numerals may be omitted. FIG. 1A is a perspective view showing a partial cross-section of a tire 10 according to the first embodiment. FIG. 1B is a cross-sectional view of a bead portion when the tire 10 according to the first embodiment is mounted on a rim. As shown in FIG. 1A, the tire 10 has a cross-sectional shape substantially the same as that of a conventionally generally used pneumatic tire made of rubber. As shown in FIG. 1A, the tire 10 includes a tire case 17 composed of only a pair of bead portions 12 that contact the bead seat 21 and the rim flange 22 of the rim 20 shown in FIG. 1B, a side portion 14 that extends radially outward of the tire from the bead portion 12, and a crown portion 16 (that is, an outer peripheral portion) that connects the radially outer ends of one side portion 14 and the other side portion 14 in the tire radial direction.

[0096] The tire case 17 corresponds to the above-described tire skeleton body and is formed of the above-described resin material. In the first embodiment, the entire tire case 17 is formed of the above-described resin material, but the present disclosure is not limited to this configuration. Similar to a conventionally generally used pneumatic tire made of rubber, different resin materials may be used for each part of the tire case 17 (for example, the side part 14, the crown part 16, the bead part 12, etc.). Further, in order to reinforce each part of the tire case 17, a reinforcing material (for example, a polymer material, a metal fiber, a cord, a non-woven fabric, a woven fabric, etc.) may be embedded and arranged in each part of the tire case 17.

[0097] The tire case 17 of the first embodiment is formed by producing two tire case halves (that is, tire skeleton pieces) in a shape in which the tread width is equally divided along the circumferential direction of the tire case 17, and joining these at the equatorial plane portion of the tire. Note that the tire case 17 is not limited to being formed by joining two members (that is, two tire case halves), and may be formed by joining three or more members.

[0098] The tire case half can be produced by methods such as vacuum forming, pressure-air forming, injection molding, and melt casting. Therefore, compared with the case of forming a tire case with rubber as in the prior art, it is not necessary to perform vulcanization, the manufacturing process can be greatly simplified, and the molding time can be shortened.

[0099] In the first embodiment, an annular bead core 18 is embedded in the bead part 12 shown in FIG. 1B, similar to a conventionally generally used pneumatic tire. In the first embodiment, a steel cord is used as the bead core 18, but an organic fiber cord, an organic fiber cord coated with resin, a hard resin cord, or the like may be used. Note that if the rigidity of the bead part 12 is ensured and the fitting with the rim 20 is good, the bead core 18 can be omitted.

[0100] In the first embodiment, an annular seal layer 24 made of a material having better sealing performance than the resin material forming the tire case 17 is formed at least at a portion in contact with the rim 20 of the bead portion 12 and at a portion in contact with at least the rim flange 22 of the rim 20. The seal layer 24 may also be formed at a portion where the bead portion 12 of the tire case 17 and the bead sheet 21 are in contact. If the sealing performance between the resin material forming the tire case 17 and the rim 20 can be ensured only by the resin material forming the tire case 17, the seal layer 24 may be omitted. Examples of the material having better sealing performance than the resin material forming the tire case 17 include a material softer than the resin material forming the tire case 17, such as rubber, a thermoplastic resin softer than the resin material, and a thermoplastic elastomer.

[0101] As shown in FIG. 1A, a reinforcing cord 26 having higher rigidity than the resin material forming the tire case 17 is wound around the crown portion 16 in the circumferential direction of the tire case 17. The reinforcing cord 26 is spirally wound in a state where at least a part thereof is embedded in the crown portion 16 in a cross-sectional view along the axial direction of the tire case 17, forming a reinforcing cord layer 28. A tread 30 made of a material having better wear resistance than the resin material forming the tire case 17, such as rubber, is disposed on the outer peripheral side in the tire diameter direction of the reinforcing cord layer 28.

[0102] In the first embodiment, as shown in FIG. 2, the reinforcing cord 26 is in a state where a metal member 26A such as a steel cord is coated with a coating resin material 27 (that is, a coated cord member). In the first embodiment, the same resin material as the resin material forming the tire case 17 is used as the coating resin material 27, but other thermoplastic resins or thermoplastic elastomers may be used. The reinforcing cord 26 is joined at the contact portion with the crown portion 16 by a method such as welding or adhesion with an adhesive. Note that the reinforcing cord 26 may be a steel cord or the like not coated with the coating resin material 27.

[0103] The elastic modulus of the resin material 27 for coating is preferably set within the range of 0.1 times to 10 times the elastic modulus of the resin material forming the tire case 17. When the elastic modulus of the resin material 27 for coating is 10 times or less the elastic modulus of the resin material forming the tire case 17, the crown portion does not become too hard and the rim assembly property becomes easy. When the elastic modulus of the resin material 27 for coating is 0.1 times or more the elastic modulus of the resin material forming the tire case 17, the resin forming the reinforcing cord layer 28 is not too soft, has excellent in-plane shear rigidity in the belt surface, and the cornering force is improved.

[0104] In the first embodiment, as shown in FIG. 2, the reinforcing cord 26 has a substantially trapezoidal cross-sectional shape. Hereinafter, the upper surface (that is, the surface on the outer side in the tire diameter direction) of the reinforcing cord 26 is denoted by reference numeral 26U, and the lower surface (that is, the surface on the inner side in the tire diameter direction) is denoted by reference numeral 26D. Also, in the first embodiment, the cross-sectional shape of the reinforcing cord 26 is configured to be substantially trapezoidal, but the present disclosure is not limited to this configuration. The reinforcing cord 26 may have any shape as long as the cross-sectional shape is not a shape that widens from the lower surface 26D side (that is, the inner side in the tire diameter direction) to the upper surface 26U side (that is, the outer side in the tire diameter direction).

[0105] As shown in FIG. 2, since the reinforcing cords 26 are arranged at intervals in the circumferential direction, a gap 28A is formed between adjacent reinforcing cords 26. For this reason, the outer peripheral surface of the reinforcing cord layer 28 has a concavo-convex shape, and the outer peripheral surface 17S of the tire case 17 constituting the outer peripheral portion by this reinforcing cord layer 28 also has a concavo-convex shape.

[0106] Fine roughened irregularities 96 are formed on the outer peripheral surface 17S (including the concavo-convexities) of the tire case 17, and the cushion rubber 29 is joined thereon via an adhesive. The cushion rubber 29 flows in so as to fill the roughened irregularities 96 at the contact surface with the reinforcing cord 26.

[0107] Above the cushion rubber 29 (i.e., on the outer peripheral surface side of the tire), the above-described tread 30 is joined. On the tread 30, a tread pattern (not shown) composed of a plurality of grooves is formed on the ground contact surface with the road surface, similar to a conventional pneumatic rubber tire.

[0108] [Manufacturing method of tire] Next, the manufacturing method of the tire of the present embodiment will be described by taking the manufacturing method of the tire according to the first embodiment as an example. (Tire case molding process) First, a tire case half is molded by injection molding or the like (molding process). By adjusting the temperature of the resin material in the molding process, for example, the cylinder temperature and the mold temperature in the case of injection molding, the long period L, the thickness La of the amorphous part, the orientation degree f, the crystallinity Xc, etc. of the thermoplastic elastomer contained in the tire case can be controlled.

[0109] Next, the annular tire case halves obtained in the molding process are joined to each other at the tire equatorial plane portion to form a tire case (joining process). Note that the tire case is not limited to being formed by joining two members, and may be formed by joining three or more members. The joining will be described. First, the tire case halves supported by a thin metal support ring are faced to each other. Next, a joining mold is installed so as to contact the outer peripheral surface of the abutting portion of the tire case half. The joining mold is configured to press the periphery of the joining portion (i.e., the abutting portion) of the tire case half with a predetermined pressure. Next, by pressing the periphery of the joining portion of the tire case half at a temperature equal to or higher than the melting point of the resin material for forming the tire case, the joining portion is melted, and the tire case halves are fused together to form a single body, and the tire case 17 is formed. For example, in this joining process, by adjusting the temperature of the resin material, for example, the temperature of the joining mold, etc., the thickness La, the long period L, the orientation degree f, and the crystallinity Xc, etc. of the amorphous part of the tire case 17 can also be controlled to be within the above-mentioned range. In the manufacturing method of the first embodiment, the joining mold was used to heat the joint of the tire case half body, but the present disclosure is not limited to this. For example, the joint may be heated by a separately provided high-frequency heating machine or the like, or may be softened or melted in advance by hot air or infrared irradiation, etc., and the tire case half body may be joined by applying pressure with a joining mold.

[0110] (Reinforcing cord member winding process) Next, the winding process of winding the reinforcing cord 26 around the tire case 17 will be described with reference to FIG. 3. FIG. 3 is an explanatory diagram for explaining the operation of embedding the reinforcing cord 26 in the crown portion of the tire case 17 using a cord heating device and rollers. In FIG. 3, the cord supply device 56 includes a reel 58 around which the reinforcing cord 26 is wound, a cord heating device 59 disposed on the downstream side in the cord conveyance direction of the reel 58, a first roller 60 disposed on the downstream side in the conveyance direction of the reinforcing cord 26, a first cylinder device 62 that moves the first roller 60 in a direction of approaching and separating from the tire outer peripheral surface, a second roller 64 disposed on the downstream side in the conveyance direction of the reinforcing cord 26 of the first roller 60, and a second cylinder device 66 that moves the second roller 64 in a direction of approaching and separating from the tire outer peripheral surface. The second roller 64 can be used as a metal cooling roller. In the first embodiment, the surface of the first roller 60 or the second roller 64 is subjected to a treatment (for example, fluororesin coating) for suppressing the adhesion of the molten or softened coating resin material 27. However, it is not limited to this mode, and the roller itself may be formed of a material to which the coating resin material 27 hardly adheres. In the first embodiment, the cord supply device 56 has two rollers, the first roller 60 and the second roller 64, but it is not limited to this mode, and it may have only one of the rollers.

[0111] The cord heating device 59 includes a heater 70 that generates hot air and a fan 72. Further, the cord heating device 59 includes a heating box 74 through which the reinforcing cord 26 passes in an internal space to which hot air is supplied, and an outlet 76 that discharges the heated reinforcing cord 26.

[0112] In this step, first, the temperature of the heater 70 of the cord heating device 59 is raised, and the surrounding air heated by the heater 70 is sent to the heating box 74 by the wind generated by the rotation of the fan 72. Next, the reinforcing cord 26 unwound from the reel 58 is sent into the heating box 74 whose internal space is heated by hot air and heated. The heating temperature is set to a temperature at which the coating resin material 27 of the reinforcing cord 26 is in a molten or softened state.

[0113] The heated reinforcing cord 26 passes through the outlet 76 and is spirally wound around the outer peripheral surface of the crown portion 16 of the tire case 17 rotating in the direction of arrow R in FIG. 3 with a certain tension. At this time, the lower surface 26D of the reinforcing cord 26 contacts the outer peripheral surface of the crown portion 16. Then, the coating resin material 27 in a molten or softened state by heating spreads on the outer peripheral surface of the crown portion 16, and the reinforcing cord 26 is welded to the outer peripheral surface of the crown portion 16. Thereby, the bonding strength between the crown portion 16 and the reinforcing cord 26 is improved.

[0114] In the first embodiment, the reinforcing cord 26 is joined to the outer peripheral surface of the crown portion 16 as described above, but the present invention is not limited to this aspect, and the joining may be performed by other methods. For example, the joining may be performed such that part or all of the reinforcing cord 26 is embedded in the crown portion 16.

[0115] (Roughening treatment step) Next, with a blasting device (not shown), while rotating the tire case 17 side, projectiles are ejected at high speed toward the outer peripheral surface 17S of the tire case 17. The ejected projectiles collide with the outer peripheral surface 17S, forming fine roughened irregularities 96 with an arithmetic mean roughness Ra of 0.05 mm or more on the outer peripheral surface 17S. By forming the fine roughened irregularities 96 on the outer peripheral surface 17S of the tire case 17, the outer peripheral surface 17S becomes hydrophilic, improving the wettability of the adhesive described later.

[0116] (Laminating process) Next, an adhesive for bonding the cushion rubber 29 is applied to the outer peripheral surface 17S of the tire case 17 that has been roughened. The adhesive is not particularly limited, and triazine thiol adhesives, chlorinated rubber adhesives, phenolic resin adhesives, isocyanate adhesives, halogenated rubber adhesives, rubber adhesives, etc. can be used. However, it is preferably one that reacts at a temperature at which the cushion rubber 29 can be vulcanized (for example, 90°C to 140°C).

[0117] Next, the unvulcanized cushion rubber 29 is wound around the outer peripheral surface 17S to which the adhesive has been applied for one turn, and an adhesive such as a rubber cement composition is applied on the cushion rubber 29. Then, the vulcanized or semi-vulcanized tread rubber 30A is wound around the cushion rubber 29 to which the adhesive has been applied for one turn to obtain a state of a raw tire case.

[0118] (Vulcanizing process) Next, the raw tire case is accommodated in a vulcanizing autoclave or mold and vulcanized. At this time, the unvulcanized cushion rubber 29 flows into the roughened irregularities 96 formed on the outer peripheral surface 17S of the tire case 17 by the roughening treatment. Then, when the vulcanization is completed, an anchor effect is exerted by the cushion rubber 29 that has flowed into the roughened irregularities 96, improving the bonding strength between the tire case 17 and the cushion rubber 29. That is, the bonding strength between the tire case 17 and the tread 30 is improved via the cushion rubber 29.

[0119] Then, if the above-described seal layer 24 is adhered to the bead portion 12 of the tire case 17 using an adhesive or the like, the tire 10 is completed.

[0120] As mentioned above, the embodiments of the present disclosure have been described by taking the first embodiment as an example. However, these embodiments are merely examples and can be implemented with various modifications without departing from the gist. Needless to say, the scope of rights of the present invention is not limited to these embodiments. For details of the embodiments applicable to the present disclosure, reference can be made to, for example, the description in Japanese Patent Application Laid-Open No. 2012-46025.

[0121] <Method for manufacturing a tire carcass> The method for manufacturing a tire carcass according to the present disclosure includes a step of melting a resin material containing a thermoplastic elastomer and a step of solidifying the resin material, and satisfies at least one of the following (1) and (2). (1) The melting is performed at a temperature A (°C) that satisfies the following formula. Melting point of thermoplastic elastomer ≤ A ≤ Melting point of thermoplastic elastomer + 20°C (2) The solidification is performed at a temperature B (°C) that satisfies the following formula. Crystallization start temperature of thermoplastic elastomer - 20°C ≤ B ≤ Crystallization start temperature of thermoplastic elastomer

[0122] When the above method satisfies (1), that is, by causing the melting of the resin material to occur at a relatively low temperature, phase separation due to the Order-Disorder transition of the thermoplastic elastomer contained in the resin material is promoted, and a thermoplastic elastomer having a large value of the long period L can be obtained.

[0123] When the above method satisfies (2), that is, by causing the solidification (crystallization) of the resin material to occur at a relatively high temperature, the cooling rate is reduced. As a result, phase separation due to the Order-Disorder transition of the thermoplastic elastomer contained in the resin material is promoted, and a thermoplastic elastomer having a large value of the long period L can be obtained.

[0124] The above method may satisfy (1) but not (2), satisfy (2) but not (1), or satisfy both (1) and (2).

[0125] From the perspective of obtaining a thermoplastic elastomer with a large value of the long period L, it is preferable that the above method further satisfies the following (3). (3) Between the melting and the solidification, the resin material is held at a temperature C (°C) that satisfies the following formula. Crystallization start temperature of the thermoplastic elastomer < C < Melting point of the thermoplastic elastomer

[0126] When the above method satisfies (3), that is, when the molten resin material is held at a temperature between the crystallization start temperature and the melting point of the thermoplastic elastomer, phase separation due to the Order-Disorder transition of the thermoplastic elastomer is promoted, and a thermoplastic elastomer with a larger value of the long period L can be obtained.

[0127] Hereinafter, the step of melting the resin material is also referred to as the "melting step", the step of solidifying the resin material is also referred to as the "solidification step", and the step of holding the molten resin material at a temperature between the crystallization start temperature and the melting point of the thermoplastic elastomer is also referred to as the "intermediate step".

[0128] When the melting step satisfies (1), the time for melting the resin material is not particularly limited as long as the melting of the resin material occurs sufficiently. For example, the time for melting the resin material may be 1 minute or more, or 5 minutes or more. The time for melting the resin material may be 30 minutes or less, or 20 minutes or less.

[0129] When the solidification step satisfies (2), the time for solidifying the resin material is not particularly limited as long as the solidification (crystallization) of the resin material occurs sufficiently. For example, the time for solidifying the resin material may be 1 minute or more, or 5 minutes or more. The time for solidifying the resin material may be 30 minutes or less, or 20 minutes or less.

[0130] When the above method has an intermediate step between the melting step and the solidification step, the time for performing the intermediate step is not particularly limited as long as the temperature of the resin material has reached the set temperature of the intermediate step. For example, the time for performing the intermediate step may be 1 minute or more, and may be 5 minutes or more. The time for performing the intermediate step may be 30 minutes or less, and may be 20 minutes or less.

[0131] In the above method, temperature A, temperature B, and temperature C may each be constant or may be changed.

[0132] In the above method, temperature A, temperature B, and temperature C are each the ambient temperature of the resin material. For example, it is the temperature of the portion of a device such as a mold, a cylinder, or a press machine used for molding the resin material that contacts the resin material.

[0133] When the resin material contains two or more kinds of thermoplastic elastomers, temperature A, temperature B, and temperature C are determined based on the melting point and the crystallization start temperature of the thermoplastic elastomer having the largest content rate on a mass basis.

[0134] The method for forming a tire carcass using the resin material is not particularly limited, and known methods such as injection molding and press molding can be adopted.

[0135] When the resin material contains components other than the thermoplastic elastomer, the content rate of the thermoplastic elastomer in the resin material is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more.

[0136] The details and preferred embodiments of the resin material and the thermoplastic elastomer used in the above method are the same as the details and preferred embodiments of the resin material used for the tire carcass of the tire described above. That is, the above method may be a method for manufacturing a tire carcass included in the tire according to the present disclosure described above.

Example

[0137] Hereinafter, the present disclosure will be described more specifically with reference to examples. However, the present disclosure is not limited thereto.

[0138] [Preparation of Samples] Using a polyester-based thermoplastic elastomer (Hytrel 5557, manufactured by Toray DuPont Co., Ltd.) in which the hard segment is polyester and the soft segment is polyether as a resin material, a sample of 100 mm × 100 mm × 2 mm was prepared using a compression molding apparatus. The melting point (melting point before molding) and crystallization start temperature of the polyester-based thermoplastic elastomer used were measured using dry resin pellets. The melting point (melting point before molding) was 208°C, and the crystallization start temperature was 185°C.

[0139] In the sample preparation, the switching of the melting process, intermediate process, and solidification process was performed by sequentially exchanging a plurality of compression molding apparatuses set so that the temperature of the portion in contact with the resin material became the temperature shown in Table 1. The prepared samples were allowed to stand in a thermostatic and humidistatic chamber at 23°C and 50% RH for at least one day before each evaluation to adjust the water absorption rate and the sample temperature.

[0140] [Measurement of Crystallization Melting Point Tm and Crystallization Start Temperature] The crystallization melting point Tm (°C) and crystallization start temperature (°C) of the obtained samples were measured by DSC. The results are shown in Table 1. As the measuring apparatus, DSC8500 (Perkin Elmer, Inc.) was used, and the measurement was carried out by placing a sample (about 15 mg) in an aluminum dish under a nitrogen atmosphere. The measurement of the crystallization melting point Tm was carried out by heating at a rate of 10°C / min in the temperature range from 25°C to 260°C, and the position of the endothermic peak top was obtained. The measurement of the crystallization start temperature was carried out by heating the sample melted by heating up to 260°C to each temperature (180°C, 185°C, 190°C, 195°C, 200°C) at a cooling rate of 50°C / min and holding isothermally for 10 minutes, and judging from the presence or absence of the peak top of the exothermic peak accompanying crystallization. The temperature at which the peak top was observed was defined as the crystallization start temperature.

[0141] [Measurement by Small-Angle X-Ray Scattering Method] The long period L of the obtained sample was measured by small-angle X-ray scattering method. The results are shown in Table 1. As the measuring device, an XRD machine (SmartLab, Rigaku Corporation) was used. A graphite monochromatized CuKα radiation beam of 45 kV and 200 mA was used as the X-ray source, and the measurement was carried out by the transmission method. The exposure time was set to 15 minutes.

[0142] [Constant-Stress Fatigue Test] As an index of the durability of the obtained sample, the following constant-stress fatigue test was carried out, and the number of repetitions (number of breakages) until the test piece broke was measured. The results are shown in Table 1. As the measuring device, MMT-250NV-10 (Shimadzu Corporation) was used. The test piece was punched out in the shape of a dumbbell-shaped No. 3 test piece specified in JIS K6251:2017, and a 1-mm cut was made on one side of the test piece with a notching machine manufactured by Dumbbell Co., Ltd. The length of the notch was confirmed with a stereomicroscope and was 0.95 mm to 1.05 mm. The fatigue test was carried out under stress control conditions, and the lower limit stress value was set to 0 MPa in order to avoid compressive load due to creep phenomenon. The upper limit stress was controlled at 15.5 MPa. The environmental temperature during the test was set to 25 °C, and the test frequency was set to 1 Hz.

[0143] [Static Tensile Test] As an index of the durability of the obtained sample, the following static tensile test was carried out, and the tensile elastic modulus and tensile yield stress of the test piece were measured. The results are shown in Table 1. As the measuring device, LITTLE SENSTAR (manufactured by Tokyo Testing Machine) was used. The test piece was manufactured by punching out in the shape of a dumbbell-shaped No. 3 test piece specified in JIS K6251:2017. The measurement conditions were a tensile speed of 150 mm / min, a chuck distance of 50 mm, and a strain rate of 0.05 s -1 as.

[0144]

Table 1

[0145] As shown in Table 1, the sample fabricated in the example where the long period L is 17.5 nm or more has a larger number of fracture cycles in the constant stress fatigue test compared to the sample fabricated in the comparative example where the long period L is less than 17.5 nm, and it can be judged that the durability is superior. In addition, it can be seen that the sample fabricated in the example where the long period L is 17.5 nm or more has a higher crystal melting point Tm, and larger tensile elastic modulus and tensile yield stress compared to the sample fabricated in the comparative example where the long period L is less than 17.5 nm.

Claims

A tire having a tire carcass formed of a resin material containing a polyester-based thermoplastic elastomer, wherein the long period L measured by the small-angle X-ray scattering method of the thermoplastic elastomer is 22.7 nm or more.

2. The tire according to claim 1, wherein the crystal melting point Tm measured by a differential scanning calorimeter of the thermoplastic elastomer is 205°C or more.

3. The tire according to claim 1 or claim 2, wherein the tensile elastic modulus of the resin material is 230 MPa or more.

4. The tire according to any one of claims 1 to 3, wherein the tensile yield stress of the resin material is 16 MPa or more.

5. A method for manufacturing a tire carcass, comprising a step of melting a resin material containing a polyester-based thermoplastic elastomer and a step of solidifying the resin material, wherein the solidification is performed at a temperature B (°C) satisfying the following formula. Crystallization start temperature of thermoplastic elastomer - 20°C ≤ B ≤ Crystallization start temperature of thermoplastic elastomer

6. A method for manufacturing a tire carcass, comprising a step of melting a resin material containing a polyester-based thermoplastic elastomer and a step of solidifying the resin material, and satisfying at least one of the following (1) and (2) and the following (3). (1) The melting is performed at a temperature A (°C) satisfying the following formula. Melting point of thermoplastic elastomer ≤ A ≤ Melting point of thermoplastic elastomer + 20°C (2) The solidification is performed at a temperature B (°C) satisfying the following formula. Crystallization start temperature of thermoplastic elastomer - 20°C ≤ B ≤ Crystallization start temperature of thermoplastic elastomer (3) The resin material is held at a temperature C (°C) satisfying the following formula between the melting and the solidification. Crystallization start temperature of thermoplastic elastomer < C < Melting point of thermoplastic elastomer

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