WO2020096000A1

WO2020096000A1 - Run flat tire

Info

Publication number: WO2020096000A1
Application number: PCT/JP2019/043698
Authority: WO
Inventors: 英幸額賀
Original assignee: 株式会社ブリヂストン
Priority date: 2018-11-09
Filing date: 2019-11-07
Publication date: 2020-05-14
Also published as: JPWO2020096000A1

Abstract

A run flat tire which is provided with: a bead core which comprises a bead wire and a covering resin layer that covers the bead wire, while being formed from a resin composition; and a side reinforcement rubber which is provided on a tire side part, while being formed from a rubber composition. This run flat tire is configured such that: the resin composition contains a thermoplastic elastomer; the 1% tensile elastic modulus of the side reinforcement rubber is 8 MPa or less; and the 100% modulus of the side reinforcement rubber is 10 MPa or more.

Description

Run flat tires

The present disclosure relates to a run flat tire.

An inner surface of a carcass of a sidewall portion of a tire, which is a so-called run-flat tire that allows the tire to safely travel a certain distance without losing its load-bearing capacity even when the inner pressure of the tire decreases due to puncture or the like. In addition, by arranging a side reinforcing rubber layer with a crescent-shaped cross-section, which has a relatively high modulus, to improve the rigidity of the side wall part, and to bear the load without significantly increasing the bending deformation of the side wall part when the internal pressure drops. There have been proposed various side-reinforcement type run flat tires, such as the above-mentioned tires and tires whose sidewalls are reinforced with various reinforcing members.

Patent Document 1 discloses a side-reinforcement type run-flat tire in which the tire side portion is reinforced with a side-reinforcing rubber to ensure durability during run-flat running (that is, during abnormal running with reduced air pressure). ..

[Patent Document 1] JP2013-95369A

The problem of the present disclosure is to provide a run flat tire that has both ride comfort during normal running and run flat running durability.

The above problems are solved by the following present disclosure.
[1] A bead wire and a bead core that covers the bead wire and has a coating resin layer formed of a resin composition,
A side reinforcing rubber formed on the tire side portion and formed of a rubber composition,
Equipped with
The resin composition contains a thermoplastic elastomer,
The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.
Runflat tire.

In the side-reinforcement type run-flat tire described in Patent Document 1, it is desirable to increase the elasticity of the side-reinforcing rubber in order to improve the durability during run-flat running, that is, the load supportability when the internal pressure decreases. On the other hand, the side-reinforcing rubber tends to have lower flexibility as the elasticity increases. As a result, the riding comfort during normal running becomes poor.
As described above, in the side-reinforcement type run-flat tire, the durability improvement during run-flat traveling and the improvement in riding comfort during normal traveling due to the side-reinforcing rubber have a trade-off relationship. However, in a runflat tire, it is desirable to achieve both the improvement in durability during runflat running and the improvement in riding comfort during normal running.
According to the present disclosure, there is provided a run-flat tire having both ride comfort during normal running and run-flat running durability.

FIG. 3 is a half cross-sectional view showing one side of a cut surface of the run-flat tire according to the present embodiment, which is cut along the tire width direction and the tire radial direction in a state of being assembled to a rim. It is a partial expanded sectional view showing a bead core in a run flat tire concerning this embodiment. It is a perspective view showing a belt layer in a run flat tire concerning this embodiment. In the run flat tire which concerns on this embodiment, it is a partial expanded sectional view which shows the modification which formed the bead core with the wire bundle which coat | covered several bead wires with the coating resin. FIG. 8 is a half cross-sectional view showing a modified example of the run-flat tire according to the present embodiment, in which a plurality of reinforcing cords are coated with a coating resin, and a belt layer is formed using a resin-coated cord having a substantially parallelogram cross section. It is a schematic diagram of a vertical cut surface to a length direction of a bead wire which shows another example of a bead part in a tire concerning this embodiment.

Hereinafter, specific embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments and is appropriately modified and implemented within the scope of the object of the present disclosure. be able to.

In the present specification, the "rubber composition" means the state of the composition before vulcanization.
In the present specification, "formed by a resin composition" means that a resin composition is molded. Further, “formed of a rubber composition” means that the rubber composition is molded. Molding of the rubber composition may include vulcanization.
In the present specification, the “resin” is a concept including a thermoplastic resin, a thermoplastic elastomer, and a thermosetting resin, and does not include rubber. Further, in the following description of the resin, “same type” means a resin having a skeleton common to the skeleton constituting the resin main chain, such as ester-based resins and styrene-based resins.
In the present specification, a numerical range represented by “to” means a range including the numerical values before and after “to” as a lower limit value and an upper limit value.
In the present specification, the term "process" is not limited to an independent process, and even if the process is not clearly distinguishable from other processes, the process is also a term of the present invention as long as the purpose is achieved. include.
In the present specification, the amount of each component in the composition is the sum of a plurality of substances present in the composition, unless a plurality of substances corresponding to each component are present in the composition. Means quantity.
In the present specification, the “main component” means a component having the largest content by mass in the mixture, unless otherwise specified.

In the present specification, the term "thermoplastic resin" means a polymer that softens and flows as the temperature rises, and becomes relatively hard and strong when the fluid is cooled, but does not have rubber-like elasticity. Means a compound.
The term "thermoplastic elastomer" as used herein means a copolymer having a hard segment and a soft segment. Examples of the thermoplastic elastomer include polymer compounds in which the material softens and flows with an increase in temperature, becomes relatively hard and strong when cooled, and has rubber-like elasticity. Specifically, as the thermoplastic elastomer, for example, a polymer that constitutes a crystalline hard segment having a high melting point or a hard segment having a high cohesive force, and a polymer that constitutes an amorphous and soft segment having a low glass transition temperature, The copolymer which has is mentioned.
The hard segment refers to a component that is relatively harder than the soft segment. The hard segment is preferably a molecular constraining component that functions as a crosslinking point of the crosslinked rubber that prevents plastic deformation. For example, the hard segment includes a structure having a rigid group such as an aromatic group or an alicyclic group in the main skeleton, or a segment capable of intermolecular packing by intermolecular hydrogen bond or π-π interaction. Can be mentioned.
The soft segment refers to a component that is relatively softer than the hard segment. The soft segment is preferably a flexible component exhibiting rubber elasticity. Examples of the soft segment include a segment having a long-chain group (for example, a long-chain alkylene group) in the main chain, a high degree of freedom of molecular rotation, and a stretchable structure.

-Runflat tire-
The run-flat tire according to the present embodiment has a bead wire and a bead core having a coating resin layer formed by coating the bead wire with a resin composition, and a side reinforcing rubber formed by a rubber composition provided in a tire side portion. And the resin composition contains a thermoplastic elastomer, the 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.

Conventionally, in run-flat tires, a technology is known in which a side reinforcing rubber formed of a rubber composition is applied to support a load during run-flat running. However, in the run-flat tire using the side reinforcing rubber and the rubber bead core, the elasticity of the side reinforcing rubber reduces the road surface followability during normal traveling, that is, the riding comfort is deteriorated due to vibration or the like. There was a problem.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have the above-mentioned configuration, and thus it is possible to achieve both riding comfort during normal traveling and traveling durability during run-flat traveling. I found that. The reason is speculated as follows.

The load on the tire during run-flat traveling, that is, when the internal pressure drops is supported by the tire side part and the bead part. Therefore, the tire side portion and the bead portion tend to be distorted according to the load applied to the tire when the internal pressure decreases.

In a conventional run-flat tire, when the coating layer of the bead core is a coating layer formed of a rubber material, the strain on the bead portion during run-flat running is large, and the strain on the tire side portion tends to be relatively small. It was
On the other hand, in the run-flat tire according to this embodiment, the coating layer of the bead core is a coating resin layer formed of a resin composition. Therefore, the bead portion tends to be suppressed from being distorted during the run-flat traveling, and the stress is relatively easily concentrated on the tire side portion, and the tire side portion is distorted. That is, the run-flat tire according to the present embodiment has a conventional run-flat tire including a bead core having a coating layer made of a rubber material, in which a difference between a strain amount during normal running and a strain amount during run-flat running in the side reinforcing rubber is different. It is considered to be larger than the tire.

Further, in the run-flat tire according to the present embodiment, the 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less. That is, the side reinforcing rubber can exhibit flexibility in a state where the strain is small. Further, the run-flat tire according to the present embodiment has a 100% modulus of the side reinforcing rubber of 10 MPa or more. That is, the side reinforcing rubber can exhibit high elasticity in a state where the strain is large.

As described above, since the run-flat tire according to the present embodiment includes the bead core having the coating resin layer, the difference between the strain amount during normal running and the strain amount during run-flat running in the side reinforcing rubber is large. And, this side reinforcing rubber satisfies the above-mentioned range of 1% tensile modulus and 100% modulus. As a result, flexibility is likely to be exhibited during normal traveling, while high elasticity is likely to be exhibited during runflat traveling. As a result, it is considered that both the riding comfort during normal running and the running durability during run-flat running are compatible.

[Properties of side reinforcing rubber]
The properties of the side reinforcing rubber will be described below.
1% Tensile Elastic Modulus The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, preferably 5 MPa or more and 8 MPa or less, and 6 MPa or more and 7 MPa or less, from the viewpoint of riding comfort during normal traveling. Is more preferable.
The 1% tensile elastic modulus of the side reinforcing rubber was measured using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd. under the conditions of an initial load of 160 mg and a frequency of 52 Hz.

A method for setting the 1% tensile elastic modulus to 8 MPa or less is not particularly limited, but for example, a method for adjusting the dispersion state of the filler in the side reinforcing rubber by configuring the side reinforcing rubber to include rubber and a filler; Examples include application of modified polybutadiene.

100% Modulus The 100% modulus of the side reinforcing rubber is 10 MPa or more, preferably 10 MPa or more and 15 MPa or less, and more preferably 11 MPa or more and 14 MPa or less from the viewpoint of run-flat running durability.

"100% modulus" is the tensile stress measured by preparing a JIS dumbbell No. 3 sample and performing a tensile test at room temperature at a speed of 500 ± 50 mm / min in accordance with JIS K6251 (2010). is there.

The method for setting the 100% modulus to 10 MPa or more is not particularly limited, and examples thereof include a method of adjusting the crosslink density of the side reinforcing rubber; a method of increasing the amount of the vulcanization accelerator.

50% modulus The 50% modulus of the side reinforcing rubber is preferably 3 MPa or more, more preferably 4 MPa or more and 6 MPa or less, and further preferably 5 MPa or more and 6 MPa or less from the viewpoint of run-flat running durability. preferable.

"50% modulus" is the tensile stress measured by preparing a JIS dumbbell No. 3 sample and conducting a tensile test at room temperature at a speed of 500 ± 50 mm / min in accordance with JIS K6251 (2010). is there.

The method for setting the 50% modulus to 3 MPa or more is not particularly limited, and examples thereof include a method of adjusting the crosslink density of the side reinforcing rubber; a method of increasing the vulcanization accelerator;

[Specific examples of run-flat tires]
The run flat tire according to the present embodiment will be described with reference to the drawings with an example.
FIG. 1 is a cross-sectional view of a run-flat tire of the present embodiment (hereinafter referred to as “tire 10”) cut along the tire width direction and the tire radial direction (a cross section viewed from the direction along the tire circumferential direction). ) Is shown on one side. The arrow W in the drawing indicates the width direction of the tire 10 (that is, the tire width direction), and the arrow R indicates the radial direction of the tire 10 (that is, the tire radial direction). The tire width direction mentioned here refers to a direction parallel to the rotation axis of the tire 10. Further, the tire radial direction means a direction orthogonal to the rotation axis of the tire 10. Reference numeral CL indicates the equatorial plane of the tire 10 (tire equatorial plane).

In the present embodiment, the side closer to the rotation axis of the tire 10 along the tire radial direction is “the tire radial direction inner side”, and the side farther from the rotation axis of the tire 10 along the tire radial direction is the “tire radial direction outer side”. Enter. On the other hand, the side closer to the tire equatorial plane CL along the tire width direction is referred to as "tire width direction inner side", and the side farther from the tire equatorial plane CL along the tire width direction is referred to as "tire width direction outer side".

(tire)
FIG. 1 shows a tire 10 when assembled to a rim 30 which is a standard rim and filled with standard air pressure. The “standard rim” referred to here is a rim defined by JATMA (Japan Automobile Tire Manufacturer's Association) Year Book 2018 version. The standard air pressure is air pressure corresponding to the maximum load capacity of Year Book 2018 version of JATMA (Japan Automobile Tire Manufacturers Association).

As shown in FIG. 1, a tire 10 is embedded in a pair of bead portions 12, a carcass 14 having a bead core 26 embedded in the bead portion 12, a carcass 14 whose end portion is locked to the bead core 26, and a bead portion 12. A bead filler 28 extending from the bead core 26 outward in the tire radial direction along the outer surface of the carcass 14, a side reinforcing rubber 24 provided in the tire side portion 22 and extending in the tire radial direction along the inner surface of the carcass 14, and a tire of the carcass 14. The belt layer 40 provided on the outer side in the radial direction and the tread 20 provided on the outer side in the tire radial direction of the belt layer 40 are provided. In FIG. 1, only the bead portion 12 on one side is shown.

The tread 20 that constitutes the outer peripheral portion of the tire 10 is provided on the outer side of the belt layer 40 in the tire radial direction. The tire side portion 22 includes a sidewall lower portion 22A on the bead portion 12 side and a sidewall upper portion 22B on the tread 20 side, and connects the bead portion 12 and the tread 20.

(Bead part)
A bead core 26 including a wire bundle is embedded in each of the pair of bead portions 12. The carcass 14 straddles these bead cores 26. As the cross-sectional structure of the bead core 26, various structures in a pneumatic tire such as a circular shape and a polygonal shape can be adopted, and as the polygonal shape, for example, a hexagonal shape can be adopted, but in the present embodiment, it is a quadrangle. It is said that.

As shown in FIG. 2, the bead core 26 is formed by winding a single bead wire 26A coated with a resin a plurality of times and laminating it. Specifically, the bead wire 26A coated with resin is wound in the tire width direction without any gap to form a first-stage row, and thereafter, the beads are stacked on the outside in the tire radial direction without any gap, and the cross-sectional shape is quadrangular. The bead core 26 is formed. At this time, the coating resins of the bead wires 26A that are adjacent to each other in the tire width direction and the tire radial direction are joined together. As a result, the bead core 26 in which the bead wire 26A is coated with the coating resin 26B is formed.

As shown in FIG. 1, in the region of the bead portion 12 surrounded by the carcass 14 (that is, the region outside the portion of the carcass 14 that is disposed inside the tire width direction around the bead core 26), the tire diameter from the bead core 26 is reduced. A resin bead filler 28 extending outward in the direction is embedded.
Although the resin-made bead filler 28 is used in the tire shown in FIG. 1, the present embodiment is not limited to this, and a rubber-made bead filler may be used.
When a rubber member such as a rubber bead filler is used in direct contact with the coating resin 26B, or when a rubber member is adjacently placed with another member interposed therebetween, the rubber material is destroyed. From the viewpoint of suppressing the deterioration of the properties, the composition does not contain a metal (for example, cobalt etc.) and a vulcanization accelerator (for example, N, N-dicyclohexylbenzothiazole-2-sulfenamide: DCBS etc.). Is preferred.

(Carcass)
The carcass 14 is a tire frame member including two carcass plies 14A and 14B. The carcass ply 14A is a carcass ply arranged on the tire equatorial plane CL on the outer side in the tire radial direction, and the carcass ply 14B is a carcass ply arranged on the inner side in the tire radial direction. Each of the carcass plies 14A and 14B is formed by coating a plurality of cords with coating rubber.

The carcass 14 thus formed extends in a toroidal shape from one bead core 26 to the other bead core 26 to form a tire skeleton. The end portion side of the carcass 14 is locked to the bead core 26. Specifically, the end portion side of the carcass 14 is folded back around the bead core 26 from the tire width direction inner side to the tire width direction outer side and locked. Further, the folded back end portions of the carcass 14 (that is, the end portions 14AE and 14BE) are arranged on the tire side portion 22. The end portion 14AE of the carcass ply 14A is arranged inside the end portion 14BE of the carcass ply 14B in the tire radial direction.

In the present embodiment, the end portion of the carcass 14 is arranged on the tire side portion 22, but the present embodiment is not limited to this structure. For example, the end portion of the carcass 14 is arranged on the belt layer 40. May be Alternatively, the end portion side of the carcass 14 may be sandwiched between a plurality of bead cores 26 or may be wound around the bead cores 26 without being folded back. In this specification, "locking" the end of the carcass 14 to the bead core 26 includes various embodiments such as these.

Note that, in the present embodiment, the carcass 14 is a radial carcass. The material of the carcass 14 is not particularly limited, and rayon, nylon, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), aramid, glass fiber, carbon fiber, steel or the like can be used. From the viewpoint of weight reduction, the organic fiber cord is preferable. Further, the number of driving the carcass is set in the range of 20 to 60 pieces / 50 mm, but the number is not limited to this range.

(Belt layer)
A belt layer 40 is disposed on the outer side of the carcass 14 in the tire radial direction. As shown in FIG. 3, the belt layer 40 is a ring-shaped broom formed by spirally winding the resin-coated cord 42 on the outer peripheral surface of the carcass 14 along the tire circumferential direction.

The resin coated cord 42 makes it difficult for the belt layer 40 to be deformed from an annular surface along the tire circumferential direction and the tire width direction to the outside of the annular surface (for example, the directions indicated by arrows C1 and C2 in FIG. 3). The reinforcing cord 42C is coated with the coating resin 42S. As shown in FIG. 1, the resin-coated cord 42 has a substantially square cross section. The coating resin 42S on the inner peripheral portion in the tire radial direction of the resin coating cord 42 is configured to be bonded to the outer peripheral surface of the carcass 14 via rubber or an adhesive. Further, the coating resins 42S that are adjacent to each other in the tire width direction of the resin coating cord 42 are integrally joined by heat welding, an adhesive, or the like. As a result, the belt layer 40 (specifically, a resin-coated belt layer) having the reinforcing cord 42C coated with the coating resin 42S is formed.

In the present embodiment, the resin coated cord 42 is configured by coating one reinforcing cord 42C with the coating resin 42S, but may be configured by coating a plurality of reinforcing cords 42C with the coating resin 42S. ..

The resin material used for the coating resin 26B of the bead core 26, the bead filler 28, and the coating resin 42S of the belt layer 40 of the present embodiment is a thermoplastic elastomer. However, the present embodiment is not limited to this, and examples of the resin material include thermoplastic resins, thermosetting resins, and general-purpose resins such as (meth) acrylic resins, EVA resins, vinyl chloride resins, fluorine resins, and silicone resins. Besides, engineering plastics and the like can be used. Note that the resin material here does not include rubber. Engineering plastics include super engineering plastics.

The resin materials used for the coating resin 26B, the bead filler 28 and the coating resin 42S will be described in detail in the section of the coating resin in the description of the bead core later.

In the present embodiment, the coating resin 42S of the belt layer 40 is made of a resin material, but the coating layer of the belt layer 40 covering the reinforcing cord 42C may be made of a rubber material. When the belt layer 40 having a rubber coating layer is used, the coating layer is a metal (for example, cobalt) and a vulcanization accelerator (for example, from the viewpoint of suppressing deterioration of the destructiveness of the rubber material). , N, N-dicyclohexylbenzothiazole-2-sulfenamide: DCBS, etc.) is preferred.
Further, also in a rubber member adjacent to the coating layer (for example, a tread under cushion, a belt under cushion provided for the purpose of providing cushioning properties), a metal (for example, cobalt or the like) and a vulcanization accelerator (for example, , N, N-dicyclohexylbenzothiazole-2-sulfenamide: DCBS, etc.) is preferred.

Also, the bead wire 26A in the bead core 26 and the reinforcing cord 42C in the belt layer 40 of the present embodiment are steel cords. This steel cord is mainly composed of steel and may contain various trace contents such as carbon, manganese, silicon, phosphorus, sulfur, copper and chromium.

The present embodiment is not limited to this, and as the bead wire 26A in the bead core 26 and the reinforcing cord 42C in the belt layer 40, a monofilament cord or a cord formed by twisting a plurality of filaments may be used instead of the steel cord. it can. Various designs can be adopted for the twist structure, and various cross-sectional structures, twist pitches, twist directions, and distances between adjacent filaments can be used. Furthermore, by adopting a cord in which filaments of different materials are twisted together, the cross-sectional structure is not particularly limited, and various twist structures such as single twist, layer twist, and multiple twist can be adopted.

(tread)
A tread 20 is provided outside the belt layer 40 in the tire radial direction. The tread 20 is a portion that comes into contact with the road surface during traveling, and a plurality of circumferential grooves 50 extending in the tire circumferential direction are formed on the tread surface of the tread 20. The shape and the number of the circumferential grooves 50 are appropriately set according to performances such as drainage and steering stability required for the tire 10.

(Side reinforcement rubber)
The tire side portion 22 is configured to extend in the tire radial direction and connect the bead portion 12 and the tread 20 to bear the load acting on the tire 10 during run flat traveling. In the tire side portion 22, a side reinforcing rubber 24 that reinforces the tire side portion 22 is provided inside the carcass 14 in the tire width direction. The side reinforcing rubber 24 is a reinforcing rubber for traveling a predetermined distance while supporting the weight of the vehicle and an occupant when the internal pressure of the tire 10 decreases due to puncture or the like.

The side reinforcing rubber 24 may be formed of one type of rubber material or may be formed of a plurality of rubber materials.

The side reinforcing rubber 24 may contain other materials such as fillers, short fibers, and resins as long as rubber is the main component, and preferably includes fillers. Further, in order to increase durability during run-flat traveling, a rubber material having a hardness of 70 to 85 may be included as the rubber material forming the side reinforcing rubber 24. The hardness of the rubber here means the hardness measured by a type A durometer, which is defined by JIS K6253. Furthermore, a loss coefficient tan δ measured using a viscoelasticity spectrometer (for example, a Toyo Seiki Seisakusho spectrometer) at a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ± 2%, and a temperature of 60 ° C. is 0.10 or less. A rubber material having physical properties may be included. The details of the rubber composition used for the side reinforcing rubber 24 will be described later.

The side reinforcing rubber 24 extends in the tire radial direction from the bead portion 12 side to the tread 20 side along the inner surface of the carcass 14. Further, the side reinforcing rubber 24 has a shape in which the thickness decreases from the central portion toward the bead portion 12 side and the tread 20 side, for example, a substantially crescent shape. The thickness of the side reinforcing rubber 24 referred to here means the length along the normal line of the carcass 14.

The lower end portion 24B of the side reinforcing rubber 24 on the bead portion 12 side overlaps the bead filler 28 with the carcass 14 in between when viewed in the tire width direction. Further, the upper end portion 24A of the side reinforcing rubber 24 on the tread 20 side overlaps with the belt layer 40 when viewed in the tire radial direction. Specifically, the upper end portion 24A of the side reinforcing rubber 24 overlaps the belt layer 40 with the carcass 14 interposed therebetween. In other words, the upper end portion 24A of the side reinforcing rubber 24 is located inside the tire width direction end portion 40E of the belt layer 40 in the tire width direction.

In the tire 10 according to the present embodiment, the bead core 26 is formed by coating the bead wire 26A with the coating resin 26B. As a result, the torsional rigidity of the bead core 26 becomes higher than that in the case where the bead wire 26A is covered with rubber. This makes it difficult for the bead portion 12 to come off from the rim 30, so that the run flat durability can be improved.

In the present embodiment, the bead core 26 is formed by winding and stacking one bead wire 26A coated with the coating resin 26B, but the present embodiment is not limited to this. For example, like a bead core 60 shown in FIG. 4, a wire bundle in which a plurality of bead wires 60A are coated with a coating resin 60B may be wound and laminated. In this case, the interface during lamination is fused by heat welding. The number of bead wires 60A included in one wire bundle is not limited to three, and may be two or four or more. Further, the number of wire bundles in each layer in which the wire bundles are laminated may be one as shown in FIG. 4 or may be two or more bundles adjacent to each other in the tire width direction.

In the present embodiment, the bead filler 28 is made of resin, but the present embodiment is not limited to this, and may be made of rubber, for example.

In the present embodiment, the belt layer 40 is formed by winding the substantially square resin-coated cord 42 formed by coating one reinforcing cord 42C with the coating resin 42S around the outer peripheral surface of the carcass 14. The form is not limited to this.

For example, as in a belt layer 70 shown in FIG. 5, a resin-coated cord 72 having a substantially parallelogram-shaped cross section formed by coating a plurality of reinforcing cords 72C with a coating resin 42S is wound around the outer peripheral surface of the carcass 14. You may form it.

The runflat tire according to this embodiment will be described in detail along with each member and material. The reference numerals are omitted.

[Bead core]
(Bead wire)
The bead wire is not particularly limited, and for example, a metal cord used for a conventional rubber tire, an organic resin cord, or the like can be appropriately used. For example, it is composed of a monofilament (that is, a single wire) such as a metal fiber or an organic fiber, or a multifilament (that is, a twisted wire) obtained by twisting these fibers. Of these, metal cords are preferable, and iron cords, that is, steel cords are more preferable.

As the bead wire in the present embodiment, a monofilament (that is, a single wire) is preferable from the viewpoint of further improving the durability of the tire. The cross-sectional shape, size (for example, diameter) of the bead wire is not particularly limited, and one suitable for a desired tire can be appropriately selected and used.
When the bead wire is a stranded wire of a plurality of cords, the number of the plurality of cords is, for example, 2 to 10, and preferably 5 to 9.

The surface of the bead wire is made of a metal material containing at least one metal element selected from the group consisting of Cu, Zn, Fe, Al, and Co as a main component from the viewpoint of adhesiveness with the adhesive layer. Is preferred.
For example, a steel cord can be given as an example of a structure containing Fe as a main component.
Further, as a structure containing at least one metal element selected from the group consisting of Cu, Zn, Al, and Co as a main component, a structure in which the surface of the steel cord is coated with plating can be mentioned.

The method for forming the plating on the surface of the cord is not particularly limited, and a known method can be used. For example, the cord, which is the core wire of the plating element wire, is passed through and immersed in, for example, a copper plating bath, a zinc plating bath, etc., to perform the plating treatment. For example, in the case of forming copper plating, it is treated with a copper cyanide bath, copper borofluoride bath, copper sulfate bath or the like, and in the case of zinc plating, it is treated with a zinc cyanide bath, zinc chloride bath, zincate bath or the like. It The cord dipped in the plating bath may be subjected to heat diffusion treatment. After that, the cord may be wire-drawn from the viewpoint of obtaining a predetermined plating thickness.

The amount of plating adhered is preferably 0.1 μm or more and 10 μm or less, more preferably 0.2 μm or more and 8.0 μm or less, for example, as the average thickness of plating. The plating thickness can be measured by observation with a scanning electron microscope (SEM).

The thickness (that is, the average diameter) of the bead wire is preferably 0.3 mm to 3 mm, and more preferably 0.5 mm to 2 mm, from the viewpoint of achieving both resistance to internal pressure and weight reduction of the tire. The thickness of the bead wire is the number average value of the thicknesses measured in five arbitrarily selected cross sections (cross sections perpendicular to the length direction of the bead wire).

The strength of the bead wire itself is usually 1000 N to 3000 N, preferably 1200 N to 2800 N, and more preferably 1300 N to 2700 N. The strength of the bead wire is calculated from the breaking point by drawing a stress-strain curve using a ZWICK type chuck with a tensile tester.

The elongation at break (that is, tensile elongation at break) of the bead wire itself is usually preferably 0.1% to 15%, more preferably 1% to 15%, and further preferably 1% to 10%. preferable. The tensile breaking elongation of the bead wire can be obtained from the strain by drawing a stress-strain curve using a ZWICK type chuck with a tensile tester.

(Adhesive layer)
The bead core according to the present embodiment may have an adhesive layer between the bead wire and the coating resin layer. The adhesive layer is preferably a layer containing a resin as an adhesive, and the resin is preferably a thermoplastic resin or a thermoplastic elastomer.

Examples of the thermoplastic resin include polyester-based thermoplastic resin, polyamide-based thermoplastic resin, polystyrene-based thermoplastic resin, polyurethane-based thermoplastic resin, and olefin-based thermoplastic resin (for example, polyethylene resin, polypropylene resin, etc.) and the like. Be done.
Examples of the thermoplastic elastomer include polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and olefin-based thermoplastic elastomers.

Among them, the resin used as the adhesive, the group consisting of polyester-based thermoplastic elastomer, polyester-based thermoplastic resin, olefin-based thermoplastic elastomer, olefin-based thermoplastic resin, polyamide-based thermoplastic elastomer, and polyamide-based thermoplastic resin It is preferable to include at least one selected from the above, and it is more preferable to include a polyester-based thermoplastic elastomer.

It is also preferable to use an acid-modified thermoplastic material for the resin used as the adhesive. The acid-modified thermoplastic material is a thermoplastic material in which an acid group is introduced into a part of the molecule of a thermoplastic resin or a thermoplastic elastomer. Examples of the acid group include a carboxy group (—COOH) and its anhydride group, a sulfuric acid group, a phosphoric acid group and the like, and among them, a carboxy group and its anhydride group are preferable.

The adhesive layer may use at least one selected from the group consisting of a thermoplastic resin and a thermoplastic elastomer. The thermoplastic resins may be used alone or in combination of two or more. The thermoplastic elastomer may be used alone or in combination of two or more.

The content of the resin contained in the adhesive layer is preferably 50% by mass or more of the entire adhesive layer, more preferably 60% by mass or more, and further preferably 75% by mass or more.

(Coating resin layer)
The bead core according to the present embodiment has a coating resin layer that covers the bead wire and is formed of a resin composition. When the bead core has the adhesive layer, the coating resin layer is provided on the adhesive layer.

The resin composition contains a thermoplastic elastomer.

-Thermoplastic Elastomer Examples of the thermoplastic elastomer include a polyamide-based thermoplastic elastomer, a polystyrene-based thermoplastic elastomer, a polyurethane-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and a polyester-based thermoplastic elastomer. The thermoplastic elastomer may be used alone or in combination of two or more.

-Polyamide thermoplastic elastomer-
A thermoplastic polyamide-based elastomer is a thermoplastic material composed of a copolymer having a polymer that forms a crystalline and hard segment with a high melting point and an amorphous polymer that forms a soft segment with a low glass transition temperature. Means a polymer having an amide bond (—CONH—) in the main chain of a polymer forming a hard segment.
As the thermoplastic polyamide-based elastomer, for example, at least polyamide is a crystalline soft segment having a high melting point, and another polymer (for example, polyester, polyether, etc.) is a soft segment having a low glass transition temperature and being amorphous. The forming material is mentioned. In addition to the hard segment and the soft segment, the polyamide-based thermoplastic elastomer may be formed using a chain extender such as dicarboxylic acid.
Specific examples of the polyamide-based thermoplastic elastomer include amide-based thermoplastic elastomer (TPA) defined in JIS K6418: 2007 and polyamide-based elastomers described in JP-A 2004-346273. it can.

In the polyamide-based thermoplastic elastomer, examples of the polyamide that forms the hard segment include a polyamide formed by a monomer represented by the following general formula (1) or (2).

In the above general formula (1), R ¹ represents a hydrocarbon molecular chain having 2 to 20 carbon atoms (for example, an alkylene group having 2 to 20 carbon atoms).

In the 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).

In the 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, and a molecular chain of hydrocarbon having 4 to 15 carbon atoms, for example, carbon An alkylene group having 4 to 15 carbon atoms is more preferable, and a hydrocarbon molecular chain having 10 to 15 carbon atoms, for example, an alkylene group having 10 to 15 carbon atoms is particularly preferable.
Further, in the general formula (2), as R ² , a hydrocarbon molecular chain having 3 to 18 carbon atoms, for example, an alkylene group having 3 to 18 carbon atoms is preferable, and a molecular chain of hydrocarbon having 4 to 15 carbon atoms, For example, an alkylene group having 4 to 15 carbon atoms is more preferable, and a hydrocarbon molecular chain having 10 to 15 carbon atoms, for example, an alkylene group having 10 to 15 carbon atoms is particularly preferable.
Examples of the monomer represented by the general formula (1) or the general formula (2) include ω-aminocarboxylic acid and lactam. Examples of polyamides that form the hard segment include polycondensates of these ω-aminocarboxylic acids or lactams, and copolycondensates of diamines and dicarboxylic acids.

Examples of ω-aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 10-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and the like having 5 to 20 carbon atoms. Examples thereof include aliphatic ω-aminocarboxylic acid. Examples of lactams include aliphatic lactams having 5 to 20 carbon atoms such as lauryl lactam, ε-caprolactam, udecane lactam, ω-enanthlactam and 2-pyrrolidone.
Examples of the diamine include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4. Examples include diamine compounds such as trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, and metaxylenediamine having 2 to 20 carbon atoms.
Further, the dicarboxylic acid can be represented by HOOC- (R ³ ) _m —COOH (R ³ : a molecular chain of a hydrocarbon having 3 to 20 carbon atoms, m: 0 or 1), and examples thereof include oxalic acid and succinic acid. And aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as glutamic 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 lauryl lactam, ε-caprolactam, or udecanlactam can be preferably used.

Examples of the polymer that forms the soft segment include polyester and polyether. Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and ABA type triblock polyether. These may be used alone or in combination of two or more. Further, polyether diamine or the like obtained by reacting the end of polyether with ammonia or the like can also be used.
Here, the "ABA type triblock polyether" means a polyether represented by the following general formula (3).

In the above general formula (3), x and z represent an integer of 1 to 20. y represents an integer of 4 to 50.

In the general formula (3), each of x and z is preferably an integer of 1 to 18, more preferably an integer of 1 to 16, further preferably an integer of 1 to 14, and particularly preferably an integer of 1 to 12. Further, in the general formula (3), y is preferably an integer of 5 to 45, more preferably an integer of 6 to 40, further preferably an integer of 7 to 35, particularly preferably an integer of 8 to 30.

As the combination of the hard segment and the soft segment, each combination of the hard segment and the soft segment mentioned above can be mentioned. Among these, as the combination of the hard segment and the soft segment, the combination of lauryl lactam ring-opening polycondensate / polyethylene glycol, the combination of lauryl lactam ring-opening polycondensate / polypropylene glycol, the lauryl lactam ring-opening polycondensation Body / polytetramethylene ether glycol combination, or a combination of lauryl lactam ring-opening polycondensate / ABA type triblock polyether, and a combination of lauryl lactam ring-opening polycondensate / ABA type triblock polyether is more preferable. preferable.

The number average molecular weight of the polymer forming the hard segment (specifically, polyamide) is preferably 300 to 15,000 from the viewpoint of melt moldability. The number average molecular weight of the polymer forming the soft segment is preferably 200 to 6000 from the viewpoint of toughness and low temperature flexibility. Further, 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 from the viewpoint of moldability. ..

The thermoplastic polyamide-based 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 polyamide-based thermoplastic elastomers include, for example, "UBESTA XPA" series (for example, XPA9063X1, XPA9055X1, XPA9048X2, XPA9048X1, XPA9040X1, XPA9040X2XPA9044, etc.) by Ube Industries, Ltd., "Vestamide" series by Daicel Eponic Corporation. (For example, E40-S3, E47-S1, E47-S3, E55-S1, E55-S3, EX9200, E50-R2, etc.) can be used.

-Polystyrene thermoplastic elastomer As the polystyrene thermoplastic elastomer, for example, at least polystyrene forms a hard segment, and a polymer other than polystyrene forms an amorphous soft segment having a low glass transition temperature. Materials are listed.
As the polystyrene that forms the hard segment, for example, polystyrene obtained by a known radical polymerization method, ionic polymerization method, or the like is preferably used, and specifically, polystyrene obtained by anion living polymerization is used.
Examples of polymers other than polystyrene that form the soft segment include polybutadiene, polyisoprene, poly (2,3-dimethyl-butadiene), polyethylene, hydrogenated polybutadiene, hydrogenated polyisoprene, and the like.

As the combination of the hard segment and the soft segment, each combination of the hard segment and the soft segment mentioned above can be mentioned. Among these, the combination of the hard segment and the soft segment is preferably the combination of polystyrene / polybutadiene or the combination of polystyrene / polyisoprene. Further, the soft segment is preferably hydrogenated in order to suppress an unintended crosslinking reaction of the thermoplastic elastomer.

The number average molecular weight of the polymer (specifically polystyrene) forming the hard segment is preferably 5,000 to 500,000, more preferably 10,000 to 200,000.
The number average molecular weight of the polymer forming the soft segment is preferably 5,000 to 1,000,000, more preferably 10,000 to 800,000, and further preferably 30,000 to 500,000. Further, the mass ratio (x: y) of the hard segment (x) and the soft segment (y) is preferably 5:95 to 80:20, more preferably 10:90 to 70:30 from the viewpoint of moldability. ..

The thermoplastic polystyrene-based 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-based copolymers [SBS (polystyrene-poly (butylene) block-polystyrene), SEBS (polystyrene-poly (ethylene / butylene) block-polystyrene)], styrene-isoprene. Copolymer (polystyrene-polyisoprene block-polystyrene), styrene-propylene copolymer [SEP (polystyrene- (ethylene / propylene) block), SEPS (polystyrene-poly (ethylene / propylene) block-polystyrene), SEEPS ( Polystyrene-poly (ethylene-ethylene / propylene) block-polystyrene), SEB (polystyrene (ethylene / butylene) block)] and the like.

Examples of commercially available polystyrene thermoplastic elastomers include, for example, "Tuftec" series manufactured by Asahi Kasei Co., Ltd. (for example, H1031, H1041, H1043, H1051, H1052, H1053, H1062, H1082, H1141, H1221, H1272, etc.) and stocks. "SEBS" series (for example, 8007, 8076, etc.), "SEPS" series (for example, 2002, 2063, etc.) manufactured by Kuraray Co., Ltd. can be used.

-Polyurethane type thermoplastic elastomer-
As the thermoplastic polyurethane-based elastomer, for example, at least polyurethane forms a hard segment in which pseudo-crosslinking is formed by physical agglomeration, and another polymer forms an amorphous soft segment having a low glass transition temperature. Ingredients are listed.
Specific examples of the polyurethane-based thermoplastic elastomer include a polyurethane-based thermoplastic elastomer (TPU) defined in JIS K6418: 2007. The polyurethane-based thermoplastic elastomer can be represented as a copolymer including a soft segment including a unit structure represented by the following formula A and a hard segment including a unit structure represented by the following formula B.

In the above 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.

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

In Formula A and Formula B, R is a partial structure introduced using 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. Can be mentioned.
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 may be used alone or in combination of two or more.

As the short-chain aliphatic hydrocarbon, alicyclic hydrocarbon or aromatic hydrocarbon represented by P ′ in the formula B, for example, those having a molecular weight of less than 500 can be used. 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, and 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, 1,10- Decanediol and the like 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, Examples thereof include 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, resorcin, 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, Examples thereof include 1-di (4-hydroxyphenyl) cyclohexane, 1,2-bis (4-hydroxyphenoxy) ethane, 1,4-dihydroxynaphthalene and 2,6-dihydroxynaphthalene.
These may be used alone or in combination of two or more.

The number average molecular weight of the polymer forming the hard segment (specifically, polyurethane) is preferably 300 to 1500 from the viewpoint of melt moldability. The number average molecular weight of the polymer forming the soft segment is preferably 500 to 20,000, more preferably 500 to 5,000, and particularly preferably 500 to 3,000, from the viewpoint of the flexibility and thermal stability of the polyurethane-based thermoplastic elastomer. .. 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. ..

The thermoplastic polyurethane-based 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 made of an aromatic diol and an aromatic diisocyanate and a soft segment made of a polycarbonate is preferable, and more specifically, a tolylene diisocyanate ( TDI) / polyester type polyol copolymer, TDI / polyether type polyol copolymer, TDI / caprolactone type polyol copolymer, TDI / polycarbonate type polyol copolymer, 4,4′-diphenylmethane diisocyanate (MDI) / polyester -Based polyol copolymers, MDI / polyether-based polyol copolymers, MDI / caprolactone-based polyol copolymers, MDI / polycarbonate-based polyol copolymers, and MDI + hydroquinone / polyhexamethylene At least one selected from the group consisting of carbonate copolymers is more preferable, and TDI / polyester-based polyol copolymers, TDI / polyether-based polyol copolymers, MDI / polyester polyol copolymers, MDI / polyether-based copolymers. At least one selected from the group consisting of a polyol copolymer and an MDI + hydroquinone / polyhexamethylene carbonate copolymer is more preferable.

Further, examples of commercially available thermoplastic polyurethane elastomers include, for example, "Elastollan" series manufactured by BASF (for example, ET680, ET880, ET690, ET890, etc.), "Kuramiron U" series manufactured by Kuraray Co., Ltd. (for example, 2000-series, 3000-series, 8000-series, 9000-series, etc., "Miractran" series (for example, XN-2001, XN-2004, P390RSUP, P480RSUI, P26MRNAT, E490, E590, P890 etc.) manufactured by Japan Miractolan Co., Ltd. Can be used.

-Olefinic thermoplastic elastomer-
As the olefin-based thermoplastic elastomer, for example, at least polyolefin forms a hard segment having a crystalline and high melting point, and another polymer (for example, a polyolefin different from the polyolefin forming the hard segment, a polyvinyl compound, etc.) is amorphous. The material forming the soft segment having a low glass transition temperature is mentioned. Examples of the polyolefin forming the hard segment include polyethylene, polypropylene, isotactic polypropylene, polybutene and the like.
Examples of the olefin-based thermoplastic elastomer include olefin-α-olefin random copolymers, olefin block copolymers, and the like. Specifically, propylene block copolymers, ethylene-propylene copolymers, propylene- 1-hexene copolymer, propylene-4-methyl-1 pentene copolymer, propylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, ethylene- 1-butene copolymer, 1-butene-1-hexene copolymer, 1-butene-4-methyl-pentene, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate Copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer Ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, propylene-methacrylic acid copolymer, propylene-methyl methacrylate copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer , Propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer, propylene-vinyl acetate copolymer and the like.

Among these, the olefin thermoplastic elastomers include propylene block copolymers, ethylene-propylene copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1pentene copolymers, propylene-1- Butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, ethylene-1-butene copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylate copolymer , Ethylene-ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, propylene-methacrylic acid copolymer , Propylene-methyl methacrylate copolymer, pro Len-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer, propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer, And at least one selected from the group consisting of propylene-vinyl acetate copolymer, ethylene-propylene copolymer, propylene-1-butene copolymer, ethylene-1-butene copolymer, ethylene-methacrylic acid. At least one selected from the group consisting of a methyl copolymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-butyl acrylate copolymer is more preferable.
Further, two or more kinds of olefin resins such as ethylene and propylene may be used in combination. The olefin resin content in the olefin-based thermoplastic elastomer is preferably 50% by mass or more and 100% by mass or less.

The number average molecular weight of the olefin-based thermoplastic elastomer is preferably 5,000 to 10,000,000. When the number average molecular weight of the olefin-based thermoplastic elastomer is 5,000 to 10,000,000, the thermoplastic resin material has sufficient mechanical properties and excellent processability. From the same viewpoint, the number average molecular weight of the olefin-based thermoplastic elastomer is more preferably 7,000 to 1,000,000, and particularly preferably 10,000 to 1,000,000. Thereby, the mechanical properties and workability of the thermoplastic resin material can be further improved. The number average molecular weight of the polymer forming the soft segment is preferably 200 to 6000 from the viewpoint of toughness and low temperature flexibility. Further, the mass ratio (x: y) of the hard segment (x) and the soft segment (y) is preferably 50:50 to 95: 5, and more preferably 50:50 to 90:10 from the viewpoint of moldability. ..
The olefin-based thermoplastic elastomer can be synthesized by copolymerization by a known method.

Moreover, as the olefin-based thermoplastic elastomer, an acid-modified thermoplastic elastomer may be used.
The "acid-modified olefin-based thermoplastic elastomer" means that an unsaturated compound having an acidic group such as a carboxylic acid group, a sulfuric acid group or a phosphoric acid group is bonded to the olefin-based thermoplastic elastomer.
To bond 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-based thermoplastic elastomer, for example, an olefin-based thermoplastic elastomer, as an unsaturated compound having an acidic group, Examples thereof include bonding (for example, graft polymerization) of unsaturated bond sites of unsaturated carboxylic acid (generally maleic anhydride).
The unsaturated compound having an acidic group is preferably an unsaturated compound having a carboxylic acid group which is a weak acid group, from the viewpoint of suppressing deterioration of the olefinic thermoplastic elastomer, for example, acrylic acid, methacrylic acid, itaconic acid, croton. Acid, isocrotonic acid, maleic acid, etc. may be mentioned.

Examples of commercially available olefin-based thermoplastic elastomers include "Toughmer" series manufactured by Mitsui Chemicals, Inc. (for example, A0550S, A1050S, A4050S, A1070S, A4070S, A35070S, A1085S, A4085S, A7090, A70090, MH7007, MH7010, MH7010, XM-7070, XM-7080, BL4000, BL2481, BL3110, BL3450, P-0275, P-0375, P-0775, P-0180, P-0280, P-0480, P-0680 etc.), Mitsui DuPont Poly "Nucrel" series manufactured by Chemical Co., Ltd. (for example, AN4214C, AN4225C, AN42115C, N0903HC, N0908C, AN42012C, N410, N1050H, N11. 8C, N1110H, N1207C, N1214, AN4221C, N1525, N1560, N0200H, AN4228C, AN4213C, N035C, etc. "Elvalloy AC" series (for example, 1125AC, 1209AC, 1218AC, 1609AC, 1820AC, 1913AC, 2112AC, 2116AC, 2615AC, 2715AC, 3117AC, 3427AC, 3717AC, etc.), Sumitomo Chemical Co., Ltd.'s “Aklift” series, “Evatate” series, etc., Tosoh Corporation's “Ultrasen” series, etc., and prime polymer “Prime TPO” series (eg, E-2900H, F-3900H, E-2900, F-3900, J-5900, E-2910, F-3910, J-5910, E-27 0, F-3710, J-5910, E-2740, F-3740, R110MP, R110E, T310E, M142E, etc.) and the like can also be used.

-Polyester thermoplastic elastomer-
As the polyester-based thermoplastic elastomer, for example, at least polyester forms a hard segment having a high melting point and another polymer (for example, polyester or polyether) is a soft segment having a low glass transition temperature and being amorphous. The forming material is mentioned.

Aromatic polyester may be used as the polyester forming the hard segment. The aromatic polyester can be formed from, for example, an aromatic dicarboxylic acid or its ester-forming derivative and an aliphatic diol. The aromatic polyester is preferably polybutylene terephthalate derived from at least one of terephthalic acid and dimethyl terephthalate and 1,4-butanediol. The aromatic polyesters include, for example, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5 A dicarboxylic acid component such as sulfoisophthalic acid or an ester-forming derivative thereof, and a diol having a molecular weight of 300 or less (eg, ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol, etc. Aliphatic diols; alicyclic diols such as 1,4-cyclohexanedimethanol and tricyclodecanedimethylol; xylylene glycol, bis (p-hydroxy) diphenyl, bis (p-hydroxyphenyl) propane, 2,2- B Sus [4- (2-hydroxyethoxy) phenyl] propane, bis [4- (2-hydroxy) phenyl] sulfone, 1,1-bis [4- (2-hydroxyethoxy) phenyl] cyclohexane, 4,4'- Aromatic diols such as dihydroxy-p-terphenyl and 4,4′-dihydroxy-p-quarterphenyl; etc.) and polyesters derived from these, or a combination of two or more of these dicarboxylic acid components and diol components It may be polymerized polyester. It is also possible to copolymerize a trifunctional or higher polyfunctional carboxylic acid component, a polyfunctional oxyacid component, a polyfunctional hydroxy component, etc. within a range of 5 mol% or less.
Examples of the polyester forming the hard segment include polyethylene terephthalate, polybutylene terephthalate, polymethylene terephthalate, polyethylene naphthalate and polybutylene naphthalate, and polybutylene terephthalate is preferable.

Examples of the polymer that forms the soft segment include aliphatic polyester and aliphatic polyether.
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, and poly (propylene oxide). ) An ethylene oxide addition polymer of glycol, a copolymer of ethylene oxide and tetrahydrofuran and the like can be mentioned.
Examples of the aliphatic polyester include poly (ε-caprolactone), polyenanthlactone, polycaprylolactone, polybutylene adipate, polyethylene adipate and the like.
Among these aliphatic polyethers and aliphatic polyesters, as the polymer forming the soft segment, poly (tetramethylene oxide) glycol and poly (propylene oxide) glycol are used from the viewpoint of the elastic properties of the obtained polyester block copolymer. Ethylene oxide adduct, poly (ε-caprolactone), polybutylene adipate, polyethylene adipate and the like are preferable.

The number average molecular weight of the polymer forming the soft segment is preferably 300 to 6000 from the viewpoint of toughness and low temperature flexibility. Further, the mass ratio (x: y) of the hard segment (x) and the soft segment (y) is preferably 99: 1 to 20:80, and more preferably 98: 2 to 30:70 from the viewpoint of moldability. ..

As a combination of the above-mentioned hard segment and soft segment, for example, each combination of the above-mentioned hard segment and soft segment can be mentioned. Among these, as the combination of the hard segment and the soft segment described above, the hard segment is polybutylene terephthalate, preferably a combination in which the soft segment is an aliphatic polyether, the hard segment is polybutylene terephthalate, the soft segment Further preferred is the combination wherein is a poly (ethylene oxide) glycol.

Commercially available polyester thermoplastic elastomers include, for example, "Hytrel" series manufactured by Toray-Dupont Co., Ltd. (for example, 3046, 5557, 6347, 4047N, 4767N, etc.), "Perprene" series manufactured by Toyobo Co., Ltd. (for example, , P30B, P40B, P40H, P55B, P70B, P150B, P280B, E450B, P150M, S1001, S2001, S5001, S6001, S9001) and the like can be used.

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.

-Thermoplastic resin The resin composition may contain a thermoplastic resin.
As the thermoplastic resin, for example, polyamide-based thermoplastic resin, polyester-based thermoplastic resin, olefin-based thermoplastic resin, polyurethane-based thermoplastic resin, vinyl chloride-based thermoplastic resin, polystyrene-based thermoplastic resin, etc. may be exemplified. it can.
Among the above, the thermoplastic resin is preferably at least one thermoplastic resin selected from the group consisting of a polyamide thermoplastic resin, a polyester thermoplastic resin, and an olefin thermoplastic resin. The thermoplastic resins may be used alone or in combination of two or more.

-Polyamide thermoplastic resin-
Examples of the polyamide-based thermoplastic resin include polyamides that form the hard segment of the above-mentioned polyamide-based thermoplastic elastomer. Specific examples of the polyamide-based thermoplastic resin include polyamide obtained by ring-opening polycondensation of ε-caprolactam (amide 6), polyamide obtained by ring-opening polycondensation of undecane lactam (amide 11), ring-opening polycondensation of lauryl lactam. Examples thereof include polyamide (amide 12), polyamide (amide 66) obtained by polycondensing diamine and dibasic acid, and polyamide (amide MX) having metaxylene diamine as a constituent unit.

The amide 6 can be represented by, for example, {CO— (CH ₂ ) ₅ —NH} _n . The amide 11 can be represented by, for example, {CO— (CH ₂ ) ₁₀ —NH} _n . The amide 12 can be represented by, for example, {CO— (CH ₂ ) ₁₁ —NH} _n . The amide 66 can be represented by, for example, {CO (CH ₂ ) ₄ CONH (CH ₂ ) ₆ NH} _n . The amide MX can be represented by, for example, the following structural formula (A-1). Here, n represents the number of repeating units.
As a commercially available product of amide 6, for example, "UBE Nylon" series (for example, 1022B, 1011FB, etc.) manufactured by Ube Industries, Ltd. can be used. As a commercially available product of the amide 11, for example, “Rilsan B” series manufactured by Arkema Ltd. can be used. As a commercially available product of the amide 12, for example, "UBE Nylon" series (for example, 3024U, 3020U, 3014U) manufactured by Ube Industries, Ltd. can be used. As a commercially available product of the amide 66, for example, "Leona" series (for example, 1300S, 1700S, etc.) manufactured by Asahi Kasei Corporation can be used. As a commercially available product of the amide MX, for example, "MX Nylon" series (for example, S6001, S6021, S6011, etc.) manufactured by Mitsubishi Gas Chemical Co., Inc. can be used.

The thermoplastic polyamide-based resin may be a homopolymer formed of only the above structural unit or a copolymer of the above structural unit and another monomer. In the case of a copolymer, the content of the above structural units in each polyamide-based thermoplastic resin is preferably 40% by mass or more.

-Polyester thermoplastic resin-
Examples of the polyester-based thermoplastic resin include polyesters that form the hard segment of the above-mentioned polyester-based thermoplastic elastomer.
Specific examples of the polyester-based thermoplastic resin include polylactic acid, polyhydroxy-3-butylbutyric acid, polyhydroxy-3-hexylbutyric acid, poly (ε-caprolactone), polyenanthlactone, polycaprylolactone, and polybutylene. Examples thereof include aliphatic polyesters such as adipate and polyethylene adipate, and aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate. Among these, polybutylene terephthalate is preferable as the polyester thermoplastic resin from the viewpoint of heat resistance and processability.

Examples of commercially available polyester thermoplastic resins include "Duranex" series manufactured by Polyplastics Co., Ltd. (e.g., 2000, 2002) and "Novaduran" series manufactured by Mitsubishi Engineering Plastics Co., Ltd. (e.g., 5010R5, 5010R3-2 etc.), “Toraycon” series manufactured by Toray Industries, Inc. (eg 1401X06, 1401X31 etc.) and the like can be used.

-Olefinic thermoplastic resin-
Examples of the olefin-based thermoplastic resin include the above-mentioned polyolefins that form the hard segment of the olefin-based thermoplastic elastomer.
Specific examples of the olefin-based thermoplastic resin include polyethylene-based thermoplastic resin, polypropylene-based thermoplastic resin, and polybutadiene-based thermoplastic resin. Among these, polypropylene-based thermoplastic resins are preferable as the olefin-based thermoplastic resin from the viewpoint of heat resistance and processability.
Specific examples of the polypropylene-based thermoplastic resin include propylene homopolymer, propylene-α-olefin random copolymer, propylene-α-olefin block copolymer and the like. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, Examples thereof include α-olefins having about 3 to 20 carbon atoms such as 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene.

As the resin contained in the coating resin layer, a thermoplastic elastomer may be used alone, or two or more thermoplastic elastomers may be used in combination, and one or more thermoplastic elastomers may be used in combination with one or more thermoplastic elastomers. Resins may be used in combination.

The total content of the thermoplastic elastomer in the coating resin layer is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 75% by mass or more with respect to the entire coating resin layer. preferable.

The coating resin layer may contain components other than the thermoplastic resin and the thermoplastic elastomer. Examples of other components include rubber, various fillers (for example, silica, calcium carbonate, clay, etc.), antioxidants, oils, plasticizers, color formers, weathering agents and the like.

(Physical properties of coating resin layer, etc.)
-Thickness The average thickness of the coating resin layer is not particularly limited. From the viewpoint of excellent durability and weldability, the thickness is preferably 10 μm or more and 1000 μm or less, and more preferably 50 μm or more and 700 μm or less.

The average thickness of the coating resin layer, the bead wire, the coating resin layer, and the SEM image of the cross section obtained by cutting the bead core along the laminating direction of the adhesive layer used as necessary is obtained from any 5 points, It is the number average value of the thickness of the coating resin layer measured from the obtained SEM image or the image obtained by a video microscope. The thickness of the coating resin layer in each SEM image is a value measured at the smallest thickness portion (the portion where the distance between the interface between the adhesive layer and the coating resin layer and the outer edge of the bead core is minimum).

Tensile Elastic Modulus The tensile elastic modulus of the coating resin layer is preferably 50 MPa or more and 1000 MPa or less, and more preferably 50 MPa or more and 800 MPa or less from the viewpoint of achieving both run flat durability and riding comfort during normal traveling. It is preferably 50 MPa or more and 700 MPa or less. The tensile elastic modulus of the coating resin layer is preferably larger than the tensile elastic modulus of the adhesive layer.

The tensile elastic modulus of the coating resin layer can be controlled by, for example, the type of resin contained in the coating resin layer. The tensile elastic modulus of the coating resin layer is measured according to JIS K7113: 1995. Specifically, for example, using Shimadzu Autograph AGS-J (5KN) manufactured by Shimadzu Corporation, the tensile speed is set to 100 mm / min, and the tensile elastic modulus is measured. When measuring the tensile elastic modulus of the coating resin layer included in the bead core, for example, a measuring sample of the same material as the coating resin layer may be separately prepared to measure the tensile elastic modulus.

・ Melt flow rate (MFR)
The melt flow rate (MFR) of the coating resin layer has an upper limit value of preferably 16.5 g / 10 min or less (260 ° C., 2.16 kg condition), more preferably 16 g / 10 min or less, and 15.4 g. It is more preferably / 10 min or less. When the MFR of the coating resin layer is 16.5 g / 10 min or less, the coating resin layer tends to exhibit excellent fatigue durability.
The lower limit of the MFR of the coating resin layer is preferably 0.5 g / 10 min or more (260 ° C., 2.16 kg condition), more preferably 2 g / 10 min or more, and 4 g / 10 min or more. More preferable. When the MFR of the coating resin layer is 0.5 g / 10 min or more, it becomes possible to perform molding in a complicated shape in extrusion molding.
The upper and lower limit values of the MFR of the coating resin layer are preferably 2 g / 10 min or more and 16 g / 10 min or less, and more preferably 4 g / 10 min or more and 15.4 g / 10 min or less.

The melt flow rate (MFR) of the coating resin layer is measured by the following method after cutting out a measurement sample from the coating resin layer. The measuring method is based on JIS-K7210-1 (2014). Specifically, MFR is performed using a melt indexer (for example, model number 2A-C, Toyo Seisakusho Co., Ltd.). The measurement conditions are a temperature of 260 ° C., a load of 2.16 kg, an interval of 25 mm, an orifice of 2.09Φ × 8 L (mm), and the MFR is obtained.

As a method for adjusting the melt flow rate (MFR) of the coating resin layer to 0.5 g / 10 min or more and 16.5 g / 10 min or less, use a thermoplastic elastomer having a MFR within the above range as the resin material; Examples include adjusting the types and amounts of the resin and additives so that the MFR falls within the above range.

-Weight average molecular weight (Mw)
The resin contained in the coating resin layer has a weight average molecular weight Mw (calculated as polymethylmethacrylate) of preferably 44,000 or more, more preferably 45,000 or more, and further preferably 47,000 or more. When the Mw of the resin is 44000 or more, the coating resin layer exhibits excellent fatigue durability.
On the other hand, the upper limit of Mw of the resin is preferably 100,000 or less, more preferably 90,000 or less, and further preferably 79000 or less. When the Mw of the resin is 100,000 or less, it becomes possible to perform molding in a complicated shape in extrusion molding.
The upper and lower limit values of Mw of the resin contained in the coating resin layer are preferably 44,000 or more and 100,000 or less, more preferably 45,000 or more and 90,000 or less, and further preferably 47,000 or more and 79000 or less.

The weight average molecular weight Mw of the resin contained in the coating resin layer is measured by the following method after cutting out a measurement sample from the coating resin layer.
The weight average molecular weight is determined by gel permeation chromatography (also referred to as “GPC”) using model number: HLC-8320GPC, manufactured by Tosoh Corporation. The measurement conditions are: column: TSK-GEL GMHXL (manufactured by Tosoh Corporation), developing solvent: HFIP (hexafluoroisopropanol, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), column temperature: 40 ° C., flow rate: 1 ml / min, Using a RI detector, the weight average molecular weight in terms of polymethylmethacrylate (PMMA) is determined.

[Side reinforcement rubber]
The side reinforcing rubber is formed of a rubber composition.

-Crosslink Density The side-reinforcing rubber preferably has a crosslink density of 5 × 10 ⁻⁴ mol / ml or more and 10 × 10 ⁻⁴ mol / ml or less, from the viewpoint of improving run flat durability, and 6 × 10 ^{−. 4} more preferably mol / ml or more 9 × is ¹⁰ -4 mol / ml or less, still more preferably 7 × ¹⁰ -4 mol / ml or more 9 × ¹⁰ -4 mol / ml or less.

The crosslink density can be controlled by adjusting the type and composition ratio of the rubber contained in the rubber composition forming the side-reinforcing rubber; adjusting the amounts and types of vulcanizing agents, vulcanization accelerators, etc.

The crosslink density is measured as the total mesh density by the swelling compression method using the theoretical formula of Flory (see, for example, Journal of Japan Rubber Association, Volume 63, No. 7, 1990, P440 to 448).

The rubber composition is kneaded using a kneading machine such as a Banbury mixer, a roll, an internal mixer, etc., is molded, and is then vulcanized to be used as a side reinforcing rubber layer of a tire.

Hereinafter, each material constituting the side reinforcing rubber will be described.
(Rubber)
Examples of the rubber include natural rubber (NR) and diene-based synthetic rubber.
Examples of the diene synthetic rubber include styrene-butadiene copolymer (SBR), polybutadiene (BR), polyisoprene (IR), styrene-isoprene copolymer (SIR), butyl rubber (IIR), halogenated butyl rubber, ethylene. -Propylene-diene terpolymer (EPDM) and mixtures thereof.
Diene synthetic rubber is a diene modified rubber in which some or all of the diene synthetic rubber has a branched structure by using a polyfunctional modifier, for example, a modifier such as tin tetrachloride. More preferably.

Examples of the rubber include those containing an amine-modified conjugated diene polymer obtained by amine-modifying a conjugated diene polymer.
The content of the amine-modified conjugated diene polymer is preferably 30% by mass or more, and particularly preferably 50% by mass or more based on the total amount of the rubber.
When the content of the amine-modified conjugated diene polymer is 30% by mass or more, the obtained rubber composition tends to have low heat generation, and thus it is considered that run-flat running durability is further improved when applied to a tire. ..

The amine-modified conjugated diene-based polymer is a conjugated diene-based polymer in which an amine-based functional group such as a protic amino group or an amino group protected by a removable group is introduced into the molecule as a modifying functional group. Preferably.
The amine-modified conjugated diene polymer is preferably a conjugated diene polymer in which, in addition to the amine functional group, a functional group containing a silicon atom is further introduced as a modifying functional group. Examples of the functional group containing a silicon atom include a silane group formed by bonding a hydrocarbyloxy group, a hydroxy group or the like to a silicon atom.

The modifying functional group may be present at any of the polymerization initiation terminal, the side chain and the polymerization active terminal of the conjugated diene polymer, but in the present embodiment, the modifying functional group is present at the polymerization terminal. Are preferred, and it is more preferred that they are present at the same polymerization active end.

Examples of the protic amino group include at least one selected from the group consisting of a primary amino group, a secondary amino group and salts thereof.
Examples of the amino group protected with a removable group include N, N-bis (trihydrocarbylsilyl) amino group and N- (trihydrocarbylsilyl) imino group. Among the above, the amino group protected by the removable group is a hydrocarbyl group containing a trialkylsilyl group having an alkyl group having 1 to 10 carbon atoms from the viewpoint of improving the dispersion of the filler. A hydrocarbyl group containing a trimethylsilyl group is more preferable.
Examples of the primary amino group protected by a removable group (hereinafter, also referred to as “protected primary amino group”) include N, N-bis (trimethylsilyl) amino group and the like.
Examples of the secondary amino group protected with a removable group include N- (trimethylsilyl) imino group and the like. The group containing an N- (trimethylsilyl) imino group may be either an acyclic imine residue or a cyclic imine residue.

When the amine-modified conjugated diene polymer is a primary amine-modified conjugated diene polymer modified with a primary amino group, protection obtained by reacting a protected primary amine compound on the active end of the conjugated diene polymer It is preferably a primary amine-modified conjugated diene-based polymer modified with a primary amino group.

The conjugated diene polymer may be a conjugated diene compound homopolymer or a copolymer of a conjugated diene compound and an aromatic vinyl compound.
Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene and 1,3-hexadiene. 1,3-butadiene is preferred. The conjugated diene compounds may be used alone or in combination of two or more.
Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene and the like. , Styrene is preferred. The aromatic vinyl compounds may be used alone or in combination of two or more.
The conjugated diene polymer is preferably polybutadiene or styrene-butadiene copolymer, and more preferably polybutadiene.

From the viewpoint of obtaining an amine-modified product by suitably reacting a protected primary amine with the active end of the conjugated diene-based polymer, at least 10% of the polymer chains have living or pseudo-living properties. preferable.

Examples of the living polymerization reaction include a reaction in which an organic alkali metal compound is used as an initiator for anionic polymerization in an organic solvent; a reaction in which an anionic polymerization is performed in a solvent containing a lanthanum series rare earth element compound for coordination anionic polymerization. Be done. The living-state polymerization reaction is preferably anionic polymerization from the viewpoint of increasing the content of vinyl bonds in the conjugated diene site and improving heat resistance.

The organic alkali metal compound is preferably an organic lithium compound such as hydrocarbyl lithium such as n-butyl lithium; a lithium amide compound such as lithium hexamethylene imide or lithium pyrrolidide. For example, when hydrocarbyl lithium is used as the organic alkali metal compound, a conjugated diene polymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being a polymerization active site can be obtained. When the lithium amide compound is used as the organic alkali metal compound, a conjugated diene polymer having a nitrogen-containing group at the polymerization initiation terminal and the other terminal being a polymerization active site can be obtained.

The method for producing the amine-modified conjugated diene polymer is not particularly limited, and a conventionally known method such as JP2011-68342A may be used.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the amine-modified conjugated diene polymer is preferably 10 to 150, more preferably 15 to 100.
When the Mooney viscosity is 10 or more, fracture resistance tends to be obtained.
When the Mooney viscosity is 150 or less, the manufacturing process such as kneading with the compounding agent tends to be easy.
The Mooney viscosity (ML _{1 + 4} , 130 ° C.) of the unvulcanized rubber composition containing the amine-modified conjugated diene polymer is preferably 10 to 150, and more preferably 30 to 100.

The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the amine-modified conjugated diene polymer, that is, the molecular weight distribution (Mw / Mn) is preferably 1 to 3, It is more preferably 1.1 to 2.7.

The number average molecular weight (Mn) of the amine-modified conjugated diene polymer is preferably 100,000 to 500,000, and more preferably 150,000 to 300,000.

The content of rubber is preferably 50% by mass or more, more preferably 50% by mass to 80% by mass, and further preferably 55% by mass to 70% by mass with respect to the total amount of the rubber composition. preferable.

(Filling material)
The rubber composition preferably contains rubber and a filler.
Examples of the filler include carbon black, silica, an inorganic filler represented by the following general formula (I), and the like.

nM · xSiO _y · zH ₂ O (I)
In the general formula (I), M is at least one metal selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, or an oxide, hydroxide, hydrate or carbonate of the metal. Represents.
In general formula (I), n represents an integer of 1 to 5. x represents an integer of 0 to 10. y represents an integer of 2 to 5. z represents an integer of 0 to 10.

Among the above, as the filler, carbon black or silica is preferable, and carbon black is more preferable.

As the carbon black, various grades of carbon black such as FEF grade, FF grade, HAF grade, ISAF grade, GPF grade and SAF grade can be used alone or in combination.
Among them, carbon black is preferably FEF grade from the viewpoint of suppressing heat generation of the tire. The silica is not particularly limited, but wet silica, dry silica and colloidal silica are preferable. These can be used alone or in an appropriate mixture.

As the inorganic filler represented by the general formula (I), M is preferably at least one selected from the group consisting of aluminum metal and aluminum oxides, hydroxides, hydrates and carbonates. ..

Specific examples of the inorganic filler represented by the general formula (I) include Al ₂ O ₃ : alumina such as γ-alumina and α-alumina; Al ₂ O ₃ .H ₂ O: alumina such as boehmite and diaspore. Hydrate; Aluminum hydroxide [Al (OH) ₃ ] such as gibbsite and bayerite; Aluminum carbonate [Al ₂ (CO ₃ ) ₂ ]; Magnesium hydroxide [Mg (OH) ₂ ]; Magnesium oxide (MgO); magnesium carbonate (MgCO _3); talc _{_{(3MgO · 4SiO 2 · H 2}} O); attapulgite _{_{(5MgO · 8SiO 2 · 9H 2}} O); titanium white _(TiO 2); titanium black _{(TiO 2n-1);} calcium oxide ( CaO); calcium hydroxide [Ca (OH) ₂ ]; magnesium aluminum oxide (MgO.Al ₂ O ₃ ); clay (Al ₂ O ₃ .2SiO ₂ ); Kaolin (Al ₂ O ₃ .2SiO ₂ 2H ₂ O); Pyrophyllite (Al ₂ O ₃ .4SiO ₂ .H ₂ O); Bentonite (Al ₂ O ₃ .4SiO ₂ 2H) ₂ O); aluminum silicates such as Al ₂ SiO ₅ and Al ₄ 3SiO ₄ 5H ₂ O; magnesium silicates such as Mg ₂ SiO ₄ and MgSiO ₃ ; calcium silicates such as Ca ₂ SiO ₄ ; Al ₂ Aluminum calcium silicate such as O ₃ · CaO · 2SiO ₂ ; magnesium calcium silicate (CaMgSiO ₄ ); calcium carbonate (CaCO ₃ ); zirconium oxide (ZrO ₂ ); zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O ]; zirconium carbonate _{_{[Zr (CO 3) 2]}} ; crystalline aluminosilicates such as zeolite; and It can be used.

In the rubber composition, various additives such as a vulcanizing agent, a vulcanization accelerator, a process oil, an anti-aging agent, an anti-scorch agent, zinc white, stearic acid, etc. are added to the extent that the effects of the present embodiment are not impaired. May be included.

The content of the filler, by increasing the dispersibility of the filler in the rubber composition, to suppress the heat generation of the tire and the decrease in the elastic modulus of the rubber, from the viewpoint of improving the riding comfort during normal traveling, It is preferably 75% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and further preferably 30% by mass or more and 65% by mass or less based on 100% by mass of rubber.

[Carcass]
In the present embodiment, the “carcass” is a member that forms the skeleton of a tire in a conventional tire, and includes so-called radial carcass, bias carcass, semi-radial carcass and the like. A carcass generally has a structure in which a reinforcing material such as a cord or a fiber is covered with a rubber material.

-Rubber material The rubber material should just contain at least rubber, and may contain other components, such as an additive, in the range which does not impair the effect concerning this embodiment. However, the content of rubber in the rubber material is preferably 50% by mass or more, and more preferably 90% by mass or more, based on the total amount of the rubber material. The carcass can be formed using, for example, a rubber material.

The rubber used for the carcass is not particularly limited, and natural rubber and various synthetic rubbers used in conventionally known rubber compounding can be used alone or in combination of two or more. For example, a rubber as shown below, or a rubber blend of two or more of these can be used.
The natural rubber may be sheet rubber or block rubber, and any of RSS # 1 to # 5 can be used.
As the synthetic rubber, various diene-based synthetic rubbers, diene-based copolymer rubbers, special rubbers and modified rubbers can be used. Specifically, for example, a butadiene-based polymer such as polybutadiene (BR), a copolymer of butadiene and an aromatic vinyl compound (for example, SBR, NBR, etc.), a copolymer of butadiene and another diene compound, and the like; Isoprene-based polymers such as polyisoprene (IR), copolymers of isoprene and aromatic vinyl compounds, copolymers of isoprene and other diene compounds; chloroprene rubber (CR); butyl rubber (IIR); halogenated Butyl rubber (X-IIR); ethylene-propylene-based copolymer rubber (EPM); ethylene-propylene-diene-based copolymer rubber (EPDM) and any blend thereof; and the like.

The rubber material used for the carcass may be added with other components such as additives to the rubber depending on the purpose.
Examples of the additive include a reinforcing material such as carbon black, a filler, a vulcanizing agent, a vulcanization accelerator, a fatty acid or a salt thereof, a metal oxide, a process oil, an antiaging agent, and the like, and these are appropriately mixed. can do.

A carcass made of rubber material is obtained by heating and vulcanizing unvulcanized rubber material.

-Other ingredients-
The rubber material may include other components than rubber, if desired. Examples of other components include resins, various fillers (eg, silica, calcium carbonate, clay), antiaging agents, oils, plasticizers, colorants, weathering agents, reinforcing materials, and the like.

As the rubber material, the material used in ordinary rubber tires can be used and is not particularly limited.

[Bead filler]
The tire according to the present embodiment may have a bead filler that extends outward in the tire radial direction from the coating resin layer in the bead portion. Further, this bead filler may be a member integrally formed with the coating resin layer.

The material of the bead filler is not particularly limited, and a conventionally known elastic material such as resin or rubber is used. The bead filler preferably contains a resin as an elastic material, and for example, those listed as the resin contained in the coating resin layer in the bead core according to the above-described embodiment are similarly used. Further, the kind of the preferable resin, the preferable content, other components that may be contained, and the like are the same as those of the coating resin layer.

[Bead part formation method]
Here, a method for forming a bead portion in the tire according to the present embodiment will be described with an example. Specifically, the forming method will be described by taking the bead portion having the configuration shown in FIG. 6 as an example.

-Formation of Adhesive Layer and First Covering Resin Layer The bead core 101 in the bead portion 110 shown in FIG. 6 can be formed as follows. First, the periphery of the bead wire 111 is covered with the adhesive layer 112, and then the three bead wires 111 covered with the adhesive layer 112 are covered with the first coating resin layer 113 to form a strip member. Furthermore, the bead core 101 is formed by winding this strip member and stacking three strip members each having a substantially rectangular cross-section.

In FIG. 6, the number of the bead wires 111 in the bead core 101 is 9, but the number is not limited to this, and the number of the bead wires 111 may be one or more, and only one. May be. Further, FIG. 6 shows a mode in which the strip members are stacked in three stages in cross section, but the structure of the stacked members is not limited to this, and for example, even if it is one stage or two stages, four stages are provided. The above may be laminated.

In the present embodiment, the outer peripheral surface of the bead wire 111 is coated with a material that forms the adhesive layer 112 in a molten state, and the surface of the material that forms the adhesive layer 112 further has a molten first coating resin layer. The strip member is formed by coating the material forming 113 (that is, the resin composition) and solidifying it by cooling. The cross-sectional shape of the strip member (that is, the shape of the cross section orthogonal to the longitudinal direction of the bead wire 111) is a substantially rectangular shape in the present embodiment, but is not limited to this, and may be various shapes such as a substantially parallelogram. be able to. The formation of the adhesive layer 112 and the formation of the first coating resin layer 113 can be performed by known methods, and examples thereof include extrusion molding. The bead core 101 can be formed by winding and stacking strip members, and the joining of the strip members is performed by melting the first coating resin layer 113 by a known method such as hot plate welding. Can be wound around and the molten first coating resin layer 113 is solidified. Alternatively, the steps can be joined by adhering the steps with an adhesive or the like.

-Formation of second coating resin layer Next, the surface of the obtained bead core 101 is coated with a material (for example, a resin) that forms the second coating resin layer 114 in a molten state, and is solidified by cooling. The coating resin layer 114 is formed. The second coating resin layer 114 can be formed by a known method, and examples thereof include injection molding.
Specifically, the bead core 101 is arranged in the cavity of the injection molding die, and the material forming the molten second coating resin layer 114 is injected into the cavity. Next, the injected material is solidified by cooling to form the second coating resin layer 114.

-Formation of bead filler The bead member 110 shown in FIG. 6 has a structure in which the bead filler 103 is arranged toward the tire radial direction outer side of the second coating resin layer 114. The bead filler 103 can be formed by a known method. For example, when the bead filler 103 is made of resin, a method such as injection molding can be used. In addition, when the bead filler 103 is a member of the same body integrally molded with the second coating resin layer 114, the bead filler 103 and the second coating resin layer 114 are processed by using an injection molding die once processed. It is also possible to integrally mold both members by injection.

As described above, according to the present disclosure, the following run flat tire is provided.
[1] A bead wire and a bead core that covers the bead wire and has a coating resin layer formed of a resin composition,
A side reinforcing rubber formed on the tire side portion and formed of a rubber composition,
Equipped with
The resin composition contains a thermoplastic elastomer,
The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.
Runflat tire.
[2] The run flat tire according to [1], wherein the melt flow rate of the coating resin layer is 0.5 g / 10 min or more and 16.5 g / 10 min or less.

[3] The runflat tire according to [1] or [2], wherein the tensile elastic modulus of the coating resin layer is 50 MPa or more and 1000 MPa or less.

[4] The runflat tire according to any one of [1] to [3], wherein the rubber composition contains rubber and a filler.

[5] The runflat tire according to [4], wherein the rubber composition contains 75 parts by mass or less of the filler with respect to 100 parts by mass of the rubber.

[6] The run according to any one of the above [1] to [5], wherein the cross-linking density of the side reinforcing rubber is 5 × 10 ⁻⁴ mol / ml or more and 10 × 10 ⁻⁴ mol / ml or less. Flat tires.

Hereinafter, the present disclosure will be described in more detail based on examples, but the present disclosure is not limited to the following examples. Materials, usage amounts, ratios, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the gist of the present embodiment. In addition, "part" represents a mass standard unless otherwise specified.

(Preparation of rubber composition for side reinforcing rubber)
A rubber composition for side-reinforcing rubber having the formulation shown in Table 1 is prepared, and is kneaded and molded by a Banbury mixer of MIXTRON BB MIXER manufactured by Kobe Steel, Ltd. to prepare an unvulcanized side-reinforcing rubber.

Details of the compounding materials shown in Table 1 are shown below.
-Synthetic rubber: the following polybutadiene rubber-filler: carbon black, N550 made by Asahi Carbon Co., Ltd.
-Antiaging agent: Hexamethylenetetramine.
-Vulcanization accelerator 1: Thiuram type compound, Nouchira TOT-N manufactured by Ouchi Shinko Chemical Co., Ltd.
-Vulcanization accelerator 2: Nocceller NS-P, manufactured by Ouchi Shinko Chemical Co., Ltd.

(Synthetic rubber synthesis example: polybutadiene rubber)
Into a nitrogen-substituted 5 L autoclave, a cyclohexane solution containing 1.4 kg of cyclohexane, 250 g of 1,3-butadiene, and 0.0285 mmol of 2,2-ditetrahydrofurylpropane was injected under nitrogen, and 2.85 mmol of n was added thereto. After adding butyllithium (BuLi), polymerization is carried out for 4.5 hours in a 50 ° C. hot water bath equipped with a stirrer. The reaction conversion of 1,3-butadiene is almost 100%. This polymer solution was extracted into a methanol solution containing 1.3 g of 2,6-di-tert-butyl-p-cresol to stop the polymerization, and then the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. To obtain polybutadiene. The polybutadiene has a microstructure (that is, vinyl bond amount) of 14%, a weight average molecular weight (Mw) of 150,000, and a molecular weight distribution (Mw / Mn) of 1.1.
The polymer solution obtained above was maintained at a temperature of 50 ° C. without deactivating the polymerization catalyst, and 1129 mg of N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane having a protected primary amino group (that is, 3 .364 mmol) is added and the denaturing reaction is carried out for 15 minutes. Finally, 2,6-di-tert-butyl-p-cresol is added to the polymer solution after the reaction. Then, the solvent removal and deprotection of the protected primary amino group are carried out by steam stripping, and the rubber is dried by a hot roll adjusted to 110 ° C. to obtain a primary amine-modified polybutadiene. The modified polybutadiene has a microstructure (that is, vinyl bond amount) of 14%, a weight average molecular weight (Mw) of 150,000, a molecular weight distribution (Mw / Mn) of 1.2, and a primary amino group content of 4.0 mmol /. It is kg.

[Examples 1-2, Comparative Examples 5-6]
(Production of resin bead member)
On the surface of a monofilament (monofilament having an average diameter of φ1.25 mm, made of steel, strength: 2700 N, elongation 7%), as an adhesive, a maleic anhydride-modified polyester thermoplastic elastomer "Primalloy-AP GQ730" manufactured by Mitsubishi Chemical Corporation. In a state of being heated and melted, it is extruded and attached by an extruder. Note that Primalloy-AP GQ730 has a melting point of 204 ° C. and a tensile elastic modulus of 300 MPa. The extrusion condition of the adhesive layer is that the temperature of the adhesive is 240 ° C.
Next, the bead wire sample to which the adhesive is attached is placed in a mold so that three bead wire samples are arranged side by side, and a polyester-based thermoplastic elastomer (specifically, manufactured by Toray DuPont Co., Ltd., trade name "Hytrel 5557") Then, it is extruded by an extruder to be adhered to the surface of the adhesive to cover and cool it to form a first coating resin layer. The extrusion temperature of the thermoplastic polyester elastomer is that the temperature of the resin is 240 ° C. A member having three bead wires formed in this way is wound while being welded with hot air. As a result, a bead core having a structure in which the nine bead wires are coated with the adhesive layer and the periphery thereof is further coated with the first coating resin layer (that is, the structure shown in FIG. 6) is produced. The average distance between adjacent bead wires is 200 μm.
Next, the bead core obtained above is placed in a mold pre-processed into the shape of a member in which the second coating resin layer and the bead filler are integrated, and the polyester-based thermoplastic elastomer (specifically, Toray DuPont Co., Ltd. Manufactured by trade name "Hytrel 5557") is injected by an injection molding machine. As a result, a bead member having a structure in which a member in which the second coating resin layer and the bead filler are integrated is formed on the outer periphery of the bead core (that is, the structure shown in FIG. 6) is manufactured. The mold temperature during injection molding is 100 ° C, and the molding temperature is 240 ° C.

(Preparation of run flat tire)
An unvulcanized carcass and belt layer is made according to the previously described embodiments. The belt layer is provided on the outer peripheral surface of the unvulcanized carcass, the unvulcanized tread is wound around the outer periphery of the belt layer, and the side reinforcing rubber made of the rubber composition shown in Tables 1 and 2 is used as the resin prepared above. Obtain a green tire combined with a bead member made of steel. Then, the obtained raw tire is vulcanized by heating at 160 ° C. for 20 minutes to obtain a tire having the structure shown in FIG. 1.
Table 2 shows the results of 1% tensile elastic modulus, 50% modulus, and 100% modulus of the rubber composition for side-reinforcing rubber measured by the above-described measuring method.

[Comparative Examples 1 to 4]
A run is performed in the same manner as in Example 1 except that the resin bead member in Example 1 is a rubber bead member and is combined with a side reinforcing rubber made of a rubber composition shown in Tables 1 and 2. Manufacture flat tires.

The rubber composition shown below was used for the rubber bead member.
-Natural rubber / filler: Asahi # 70K, manufactured by Asahi Carbon Co., Ltd.
-Anti-aging agent: Non-flex RD-S, manufactured by Seiko Chemical Co., Ltd.
-Vulcanization accelerator 1: Nocceller H, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.-Vulcanization accelerator 2: Sunceller CM-G, manufactured by Sanshin Chemical Industry Co., Ltd.

-Evaluation-
(Ride comfort during normal driving)
The longitudinal spring constant is measured when the internal pressure of each tire is 230 kPa.
The evaluation is expressed as an index with the measured value of Comparative Example 1 being 100, and the smaller the value, the higher the riding comfort. If the index is 100 or more, it means that the riding comfort does not change. The results are shown in Table 2.

(Run-flat running durability)
In an indoor drum test based on the ISO standard, run flat running at an internal pressure of 0 kPa and a speed of 80 km / h. The traveling distance until the traveling becomes impossible due to a tire failure or a support failure is measured, and an index when the traveling distance in Comparative Example 1 is 100 is obtained. The results are shown in Table 2. It should be noted that the larger the index, the better the run-flat running property (that is, the durability).

The rubber compositions A to D shown in Table 1 are all synthetic materials.
Regarding the results of each evaluation test shown in Table 2, Example 1 and Comparative Examples 1 to 4 are data obtained by actually carrying out the test. On the other hand, Example 2 is prediction data by simulation.

From the above results, it can be seen that the run-flat tire of the example has both better riding comfort during normal running and run-flat running durability than the run-flat tire of the comparative example.

The disclosure of Japanese Patent Application No. 2018-212515 filed on Nov. 9, 2018 is incorporated herein by reference in its entirety.
All publications, patent applications, and technical standards mentioned herein are to the same extent as if each individual publication, patent application, and technical standard were specifically and individually noted to be incorporated by reference, Incorporated herein by reference.

10 tires (run flat tires)
14 Carcass 22 ... Tire side part 24 Side reinforcement rubber 26 Bead core 26A Bead wire (wire)
26B coating resin 28 bead filler 40 belt layer,
42C reinforcement cord (cord)
101 bead core 103 bead filler 110 bead part 111 bead wire 112 adhesive layer 113 first coating resin layer 114 second coating resin layer

Claims

A bead wire and a bead core having a coating resin layer formed by coating the bead wire with a resin composition,
A side reinforcing rubber formed on the tire side portion and formed of a rubber composition,
Equipped with
The resin composition contains a thermoplastic elastomer,
The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.
Runflat tire.
The run-flat tire according to claim 1, wherein the melt flow rate of the coating resin layer is 0.5 g / 10 min or more and 16.5 g / 10 min or less.
The run-flat tire according to claim 1 or 2, wherein the tensile elastic modulus of the coating resin layer is 50 MPa or more and 1000 MPa or less.
The runflat tire according to any one of claims 1 to 3, wherein the rubber composition contains a rubber and a filler.
The run-flat tire according to claim 4, wherein the rubber composition contains 75 parts by mass or less of the filler with respect to 100 parts by mass of the rubber.
The run-flat tire according to any one of claims 1 to 5, wherein the cross-linking density of the side reinforcing rubber is 5 × 10 −4 mol / ml or more and 10 × 10 −4 mol / ml or less.