JPWO2020096000A1 - Run flat tire - Google Patents

Abstract

A bead core having a bead wire and a coating resin layer covering the bead wire and formed of a resin composition, and a side reinforcing rubber provided on a tire side portion and formed of the rubber composition are provided. A run-flat tire containing a thermoplastic elastomer, the 1% tensile elasticity of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.

Description

The present disclosure relates to run-flat tires.

Even when the internal pressure of the tire is reduced due to a flat tire or the like, the inner surface of the carcass on the sidewall of the tire is used as a so-called run-flat tire that allows the tire to safely travel a certain distance without losing its load bearing capacity. In addition, a crescent-shaped side reinforcing rubber layer with a relatively high modulus is arranged to improve the rigidity of the sidewall part so that the load can be borne without extremely increasing the bending deformation of the sidewall part when the internal pressure drops. Various side-reinforced run-flat tires have been proposed, such as tires with flat tires and tires with sidewalls reinforced with various reinforcing members.

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

[Patent Document 1] Japanese Unexamined Patent Publication No. 2013-95369

An object 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 problem is solved by the following disclosure.
[1] A bead core having a bead wire and a coating resin layer formed by coating the bead wire and a resin composition, and a bead core.
Side reinforcing rubber provided on the tire side and formed by the rubber composition,
With
The resin composition contains a thermoplastic elastomer and contains
The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.
Run-flat tires.

In the side-reinforced run-flat tire described in Patent Document 1, it is desirable to increase the elasticity of the side-reinforced rubber in order to improve the durability during run-flat running, that is, the load bearing capacity when the internal pressure is lowered. On the other hand, the flexibility of the side reinforcing rubber tends to decrease as the elasticity increases. Therefore, the ride quality during normal driving becomes poor.
As described above, in the side-reinforced run-flat tire, the improvement of durability during run-flat running and the improvement of riding comfort during normal running by the side-reinforced rubber are in a trade-off relationship. However, for run-flat tires, it is desirable to achieve both the improvement of durability during run-flat running and the improvement of riding comfort during normal running.
According to the present disclosure, a run-flat tire having both ride comfort during normal running and run-flat running durability is provided.

It is a half cross-sectional view which shows one side of the cut surface which cut along the tire width direction and the tire radial direction in the state which the run-flat tire which concerns on this embodiment is assembled to a rim. It is a partially enlarged sectional view which shows the bead core in the run-flat tire which concerns on this embodiment. It is a perspective view which shows the belt layer in the run-flat tire which concerns on this embodiment. FIG. 5 is a partially enlarged cross-sectional view showing a modified example in which a bead core is formed by a wire bundle in which a plurality of bead wires are coated with a coating resin in the run-flat tire according to the present embodiment. It is a half-cross-sectional view which shows the modification which formed the belt layer by using the resin coating cord which the cross section has a substantially parallel quadrilateral shape in which a plurality of reinforcing cords were coated with coating resin in the run-flat tire which concerns on this embodiment. It is a schematic diagram of the cut plane perpendicular to the length direction of the bead wire which shows another example of the bead part in the tire which concerns on 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 carried out with appropriate modifications within the scope of the purpose of the present disclosure. be able to.

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

Further, in the present specification, the term "thermoplastic resin" refers to a polymer that softens and flows as the temperature rises, and when the fluid is cooled, it becomes relatively hard and strong, but does not have rubber-like elasticity. Means a compound.
As used herein, the term "thermoplastic elastomer" means a copolymer having a hard segment and a soft segment. Examples of the thermoplastic elastomer include polymer compounds that soften and flow as the temperature rises, become relatively hard and strong when cooled, and have rubber-like elasticity. Specifically, as the thermoplastic elastomer, for example, a polymer constituting a crystalline hard segment having a high melting point or a hard segment having a high cohesive force, and a polymer constituting an amorphous soft segment having a low glass transition temperature may be used. Examples thereof include copolymers having.
The hard segment refers to a component that is relatively harder than the soft segment. The hard segment is preferably a molecular restraint component that serves as a cross-linking point of the cross-linked rubber that prevents plastic deformation. For example, as a hard segment, a segment having a rigid group such as an aromatic group or an alicyclic group in the main skeleton, or a structure that enables intermolecular packing by intermolecular hydrogen bonds or π-π interactions can be used. Can be mentioned.
Further, 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. For example, 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 in molecular rotation, and a stretchable structure.

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

Conventionally, in a run-flat tire, a technique of applying a side reinforcing rubber formed of a rubber composition for load support during run-flat running has been known. However, in a run-flat tire using the side reinforcing rubber and a rubber bead core, the elasticity of the side reinforcing rubber reduces the road surface followability during normal driving, that is, the riding comfort is lowered due to vibration or the like. There was a problem.

As a result of diligent studies to solve the above problems, the present inventors can achieve both ride comfort during normal running and running durability during run-flat running by having the above configuration. I found that. The reason can be inferred as follows.

The load applied to the tire during run-flat running, that is, when the internal pressure is lowered, is supported by the tire side portion and the bead portion. 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 is lowered.

In a conventional run-flat tire, when the coating layer of the bead core is a coating layer formed of a rubber material, the distortion of the bead portion during run-flat running tends to be large, and the distortion of the tire side portion tends not to be relatively large. rice field.
On the other hand, the run-flat tire according to the present embodiment is a coating resin layer in which the coating layer of the bead core is formed of the resin composition. Therefore, the distortion of the bead portion during run flat running tends to be suppressed, the stress tends to be relatively concentrated on the tire side portion, and the distortion of the tire side portion becomes large. That is, in the run-flat tire according to the present embodiment, the difference between the amount of strain during normal running and the amount of strain during run-flat running in the side reinforcing rubber is a conventional run-flat provided with a bead core having a coating layer made of a rubber material. It is thought to be larger than a 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, in the run-flat tire according to the present embodiment, the 100% modulus of the side reinforcing rubber is 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 a bead core having a coating resin layer, the difference between the amount of strain during normal running and the amount of strain during run-flat running in the side reinforcing rubber is large. Moreover, this side reinforcing rubber satisfies the 1% tensile modulus and 100% modulus in the above range. As a result, flexibility is likely to be exhibited during normal running, while high elasticity is likely to be exhibited during run-flat running. As a result, it is considered that both the riding comfort during normal running and the running durability during run-flat running are compatible.

[Characteristics of side reinforcing rubber]
Hereinafter, the properties of the side reinforcing rubber will be described.
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 driving. 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.

The method for setting the 1% tensile elastic modulus to 8 MPa or less is not particularly limited, but for example, a method in which the side reinforcing rubber is configured to include rubber and a filler, and the dispersed state of the filler in the side reinforcing rubber is adjusted; Examples include the application of modified polybutadiene.

100% modulus The 100% modulus of the side reinforcing rubber is preferably 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-shaped No. 3 sample and performing a tensile test at a speed of 500 ± 50 mm / min at room temperature in accordance with JIS K6251 (2010). be.

The method of 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-shaped No. 3 sample and performing a tensile test at a speed of 500 ± 50 mm / min at room temperature in accordance with JIS K6251 (2010). be.

The method of 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 amount of 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 shows a cut surface (cross section seen from a direction along the tire circumferential direction) cut along the tire width direction and the tire radial direction of the run-flat tire (hereinafter, referred to as “tire 10”) of the present embodiment. ) Is shown on one side. In the drawing, the arrow W 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 referred to 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. Further, the reference numeral CL indicates the equatorial plane (tire equatorial plane) of the tire 10.

Further, in the present embodiment, the side close to the rotation axis of the tire 10 along the tire radial direction is "inside in the tire radial direction", and the side far from the rotation axis of the tire 10 along the tire radial direction is "outside in the tire radial direction". It is described as. On the other hand, the side close to the tire equatorial plane CL along the tire width direction is described as "inside in the tire width direction", and the side far from the tire equatorial plane CL along the tire width direction is described as "outside in the tire width direction".

(tire)
FIG. 1 shows a tire 10 when assembled on a rim 30 which is a standard rim and filled with standard air pressure. The "standard rim" here refers to the rim specified by JATMA (Japan Automobile Tire Association) Year Book 2018 edition. The standard air pressure is the air pressure corresponding to the maximum load capacity of the Year Book 2018 version of JATTA (Japan Automobile Tire Association).

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

A tread 20 forming an 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 is composed of 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. A 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 circle and a polygon can be adopted, and as the polygon, for example, a hexagon can be adopted, but in the present embodiment, a quadrangle can be adopted. It is said that.

As shown in FIG. 2, the bead core 26 is formed by winding one bead wire 26A coated with a resin a plurality of times and laminating them. Specifically, the bead wire 26A coated with resin is wound tightly in the tire width direction to form the first row, and thereafter, the bead wires 26A are stacked outward in the tire radial direction without gaps in the same manner, and the cross-sectional shape is square. The bead core 26 is formed. At this time, the coating resins of the bead wires 26A adjacent to each other in the tire width direction and the radial direction are joined to each other. 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 surrounded by the carcass 14 of the bead portion 12 (that is, the region outside the portion of the carcass 14 arranged inward in the tire width direction around the bead core 26), the tire diameter is from the bead core 26. A resin bead filler 28 extending outward in the direction is embedded.
Although the resin bead filler 28 is used in the tire shown in FIG. 1, the present embodiment is not limited to this, and a rubber 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 used adjacent to another member with another member in between, the rubber material is destroyed. The composition does not contain a metal (for example, cobalt, etc.) and a vulcanization accelerator (for example, N, N-dicyclohexylbenzothiazole-2-sulfenamide: DCBS, etc.) from the viewpoint of suppressing deterioration of the property. Is preferable.

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

The carcass 14 thus formed extends from one bead core 26 to the other bead core 26 in a toroid shape to form a tire skeleton. Further, the end side of the carcass 14 is locked to the bead core 26. Specifically, the carcass 14 is locked so that the end side is folded back around the bead core 26 from the inside in the tire width direction to the outside in the tire width direction. Further, the folded end portions (that is, the end portions 14AE and 14BE) of the carcass 14 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 configuration, and for example, the end portion of the carcass 14 is arranged on the belt layer 40. May be. Further, it is also possible to adopt a structure in which the end side of the carcass 14 is not folded back and is sandwiched between a plurality of bead cores 26 or wound around the bead core 26. As used herein, "locking" the end of the carcass 14 to the bead core 26 includes various embodiments such as these.

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 and the like can be adopted. From the viewpoint of weight reduction, the organic fiber cord is preferable. Further, the number of carcass driven is in the range of 20 to 60/50 mm, but the number is not limited to this range.

(Belt layer)
A belt layer 40 is arranged 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 sword formed by spirally winding the resin coating cord 42 around the outer peripheral surface of the carcass 14 along the tire circumferential direction.

The resin coating cord 42 makes it difficult for the belt layer 40 to be deformed from the 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 of the inner peripheral portion of the resin coating cord 42 in the tire radial direction is formed by being joined to the outer peripheral surface of the carcass 14 via rubber or an adhesive. Further, the coating resins 42S 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, the resin-coated belt layer) having the reinforcing cord 42C coated with the coating resin 42S is formed.

In the present embodiment, the resin coating 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 in the bead core 26 of the present embodiment, the bead filler 28, and the coating resin 42S in the belt layer 40 is a thermoplastic elastomer. However, this embodiment is not limited to this, and for example, as a resin material, a thermoplastic resin, a thermosetting resin, and a general-purpose resin such as a (meth) acrylic resin, an EVA resin, a vinyl chloride resin, a fluororesin, and a silicone resin are used. In addition, engineering plastics and the like can be used. 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 item of the coating resin in the description of the bead core later.

In the present embodiment, the coating resin 42S in the belt layer 40 is formed by using a resin material, but the coating layer covering the reinforcing cord 42C in the belt layer 40 may be formed by a rubber material. When the belt layer 40 having a rubber coating layer is used, the coating layer is made of a metal (for example, cobalt or the like) and a vulcanization accelerator (for example, for example) from the viewpoint of suppressing deterioration of the destructive property of the rubber material. , N, N-dicyclohexylbenzothiazole-2-sulfenamide: DCBS, etc.) is preferably not contained.
Further, in the rubber member adjacent to the coating layer (for example, tread under cushion, belt under cushion, etc. provided for the purpose of imparting cushioning property), a metal (for example, cobalt or the like) and a vulcanization accelerator (for example, for example) are also used. , N, N-dicyclohexylbenzothiazole-2-sulfenamide: DCBS, etc.) is preferably not contained.

Further, 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 contains steel as a main component and may contain various trace substances 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 obtained by twisting a plurality of filaments may be used instead of the steel cord. can. Various designs can be adopted for the twist structure, and various designs can be used for the cross-sectional structure, the twist pitch, the twist direction, and the distance between adjacent filaments. Furthermore, by adopting a cord in which filaments of different materials are twisted together, the cross-sectional structure is not particularly limited, and various twisted structures such as single twist, layer twist, and double twist can be taken.

(tread)
A tread 20 is provided on the outer side of 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 number of the circumferential grooves 50 are appropriately set according to the performance such as drainage and steering stability required for the tire 10.

(Side reinforcement rubber)
The tire side portion 22 extends in the tire radial direction to connect the bead portion 12 and the tread 20 so that the load acting on the tire 10 can be borne during run-flat running. Inside the tire side portion 22 of the carcass 14 in the tire width direction, a side reinforcing rubber 24 for reinforcing the tire side portion 22 is provided. The side reinforcing rubber 24 is a reinforcing rubber for traveling a predetermined distance while supporting the weights of the vehicle and the occupant when the internal pressure of the tire 10 is reduced 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 a filler, short fibers, and resin as long as the rubber is the main component, and preferably contains the filler. Further, in order to enhance the durability during run-flat running, a rubber material having a hardness of 70 to 85 may be included as the rubber material constituting the side reinforcing rubber 24. The hardness of rubber here refers to the hardness measured by a type A durometer defined by JIS K6253. Further, the loss coefficient tan δ measured using a viscoelastic spectrometer (for example, a spectrometer manufactured by Toyo Seiki Seisakusho) under the conditions of 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 from the bead portion 12 side to the tread 20 side in the tire radial direction 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 refers to 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 from 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 from 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 is increased as compared with the case where the bead wire 26A is covered with rubber. As a result, the bead portion 12 is less likely 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 one bead wire 26A coated with the coating resin 26B and laminating it, but the present embodiment is not limited to this. For example, as in the bead core 60 shown in FIG. 4, a plurality of bead wires 60A may be formed by winding and laminating a wire bundle coated with a coating resin 60B. In this case, the interface at the time of 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 on which the wire bundles are laminated may be one bundle 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 formed of, for example, rubber.

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

For example, like the belt layer 70 shown in FIG. 5, a resin-coated cord 72 having a substantially parallel quadrilateral 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. May be formed.

The run-flat tire according to the present 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 stranded wire) obtained by twisting these fibers. Among them, a metal cord is preferable, and an iron cord, that is, a steel cord is 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) and the like of the bead wire are not particularly limited, and those 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 includes, for example, 2 to 10, preferably 5 to 9.

The surface of the bead wire is composed 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 to the adhesive layer. It is preferable to have.
For example, as a configuration containing the Fe element as a main component, a steel cord can be mentioned.
Further, as a configuration containing at least one metal element selected from the group consisting of Cu, Zn, Al, and Co as a main component, a configuration in which the surface of the steel cord is coated by 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 strand, is passed through and immersed in, for example, a copper plating bath, a zinc plating bath, or the like, and the plating treatment is performed. For example, in the case of forming copper plating, it is treated in a copper cyanide bath, a borofluoride bath, a copper sulfate bath, etc., and in the case of zinc plating, it is treated in a zinc cyanide bath, a zinc chloride bath, a zincate bath, etc. NS. The cord immersed in the plating bath may be subjected to a heat diffusion treatment. After that, the cord may be drawn from the viewpoint of achieving a predetermined plating thickness.

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

The thickness of the bead wire (that is, the average diameter) is preferably 0.3 mm to 3 mm, more preferably 0.5 mm to 2 mm, from the viewpoint of achieving both internal pressure resistance and weight reduction of the tire. The thickness of the bead wire is the average value of the thicknesses measured at 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 1000N to 3000N, preferably 1200N to 2800N, and more preferably 1300N to 2700N. 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 breaking elongation (that is, tensile breaking elongation) 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 elongation at break 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, 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 an adhesive includes a group consisting of polyester-based thermoplastic elastomers, polyester-based thermoplastic resins, olefin-based thermoplastic elastomers, olefin-based thermoplastic resins, polyamide-based thermoplastic elastomers, and polyamide-based thermoplastic resins. It is preferable to contain at least one selected from the above, and it is more preferable to contain 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 a molecule of a thermoplastic resin or a thermoplastic elastomer. Examples of the acid group include a carboxy group (-COOH) and an anhydride group thereof, a sulfate group, a phosphoric acid group and the like, and among them, a carboxy group and an anhydride group thereof are preferable.

As the adhesive layer, at least one selected from the group consisting of a thermoplastic resin and a thermoplastic elastomer may be used. The thermoplastic resin 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, more preferably 60% by mass or more, and further preferably 75% by mass or more of the entire adhesive layer.

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

The resin composition comprises a thermoplastic elastomer.

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

-Polyamide-based thermoplastic elastomer-
A polyamide-based thermoplastic elastomer is a thermoplastic material composed of a copolymer having a polymer that forms a hard segment that is crystalline and has a high melting point and a polymer that forms a soft segment that is amorphous and has a low glass transition temperature. It means a polymer having an amide bond (-CONH-) in the main chain of the polymer forming the hard segment.
As the polyamide-based thermoplastic elastomer, for example, at least polyamide forms a hard segment having a high crystallinity and a high melting point, and other polymers (for example, polyester, polyether, etc.) are amorphous and have a low glass transition temperature. Examples include the forming material. Further, the polyamide-based thermoplastic elastomer may be formed by using a chain length extender such as a dicarboxylic acid in addition to the hard segment and the soft segment.
Specific examples of the polyamide-based thermoplastic elastomer include the amide-based thermoplastic elastomer (TPA) defined in JIS K6418: 2007, the polyamide-based elastomer described in JP-A-2004-346273, and the like. can.

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

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

In the above general formula (2), R ² represents a molecular chain of a hydrocarbon having 3 to 20 carbon atoms (for example, an alkylene group having 3 to 20 carbon atoms).

In the general formula (1), as R ¹ , a molecular chain of a hydrocarbon having 3 to 18 carbon atoms, for example, an alkylene group having 3 to 18 carbon atoms is preferable, and a molecular chain of a hydrocarbon having 4 to 15 carbon atoms, for example, carbon. An alkylene group having a number of 4 to 15 is more preferable, and a molecular chain of a hydrocarbon 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), the ^{R 2,} the molecular chains of hydrocarbon having 3 to 18 carbon atoms, for example, preferably an alkylene group having 3 to 18 carbon atoms, the molecular chain of a hydrocarbon of 4 to 15 carbon atoms, For example, an alkylene group having 4 to 15 carbon atoms is more preferable, and a molecular chain of a hydrocarbon 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 the polyamide forming the hard segment include a polycondensate of these ω-aminocarboxylic acids or lactams, a co-condensation polymer of a diamine and a dicarboxylic acid, and the like.

Examples of the 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. An aliphatic ω-aminocarboxylic acid and the like can be mentioned. Examples of the lactam include aliphatic lactams having 5 to 20 carbon atoms such as lauryl lactam, ε-caprolactam, udecan lactam, ω-enantractum, and 2-pyrrolidone.
Examples of the diamine include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4. Examples thereof include diamine compounds such as aliphatic diamines having 2 to 20 carbon atoms such as −trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 3-methylpentamethylenediamine, and metaxylene diamine.
Further, the dicarboxylic acid can be represented by HOOC- (R ³ ) _m- COOH (R ³ : molecular chain of hydrocarbon having 3 to 20 carbon atoms, m: 0 or 1), for example, oxalic acid, succinic acid. , Glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid and other aliphatic dicarboxylic acids having 2 to 20 carbon atoms can be mentioned.
As the polyamide forming the hard segment, a polyamide obtained by ring-opening polycondensation of lauryl lactam, ε-caprolactam, or udecan lactam can be preferably used.

Examples of the polymer forming the soft segment include polyester and polyether, and specific examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and ABA-type triblock polyether. These can be used alone or in combination of two or more. Further, a polyether diamine or the like obtained by reacting the terminal of the 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 integers of 1 to 20. y represents an integer from 4 to 50.

In the general formula (3), x and z are preferably integers of 1 to 18, more preferably integers of 1 to 16, even more preferably integers of 1 to 14, and particularly preferably integers 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, and particularly preferably an integer of 8 to 30.

Examples of the combination of the hard segment and the soft segment include the respective combinations of the hard segment and the soft segment mentioned above. Among these, the combination of the hard segment and the soft segment includes a combination of lauryl lactam open ring polycondensate / polyethylene glycol, a combination of lauryl lactam open ring polycondensate / polypropylene glycol, and a combination of lauryl lactam open ring polycondensate. A combination of body / polytetramethylene ether glycol or a ring-opened polycondensate of lauryl lactam / ABA-type triblock polyether is preferable, and a combination of lauryl lactam ring-opened polycondensate / ABA-type triblock polyether is more preferable. preferable.

The number average molecular weight of the polymer (specifically, polyamide) forming the hard segment 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, more preferably 50:50 to 80:20 from the viewpoint of moldability. ..

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

Commercially available products of polyamide-based thermoplastic elastomers include, for example, the "UBESTA XPA" series of Ube Industries, Ltd. (for example, XPA9063X1, XPA9055X1, XPA9048X2, XPA9048X1, XPA9040X1, XPA9040X2XPA9044, etc.), and the "Vestamide" series of Daicel Eponic Co., Ltd. (For example, E40-S3, E47-S1, E47-S3, E55-S1, E55-S3, EX9200, E50-R2, etc.) and the like can be used.

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

Examples of the combination of the hard segment and the soft segment include the respective combinations of the hard segment and the soft segment mentioned above. Among these, as the combination of the hard segment and the soft segment, a polystyrene / polybutadiene combination or a polystyrene / polyisoprene combination is preferable. In addition, the soft segment is preferably hydrogenated in order to suppress an unintended cross-linking reaction of the thermoplastic elastomer.

The number average molecular weight of the polymer (specifically polystyrene) forming the hard segment is preferably 5000 to 500000, more preferably 1000 to 20000.
The number average molecular weight of the polymer forming the soft segment is preferably 5000 to 1,000,000, more preferably 1000 to 8,000,000, and even more preferably 30,000 to 500000. 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. ..

Polystyrene-based thermoplastic elastomers can be synthesized by copolymerizing a polymer forming a hard segment and a polymer forming a soft segment by a known method.
Examples of polystyrene-based thermoplastic elastomers include styrene-butadiene-based copolymers [SBS (polystyrene-poly (butylene) block-polystyrene), SEBS (polystyrene-poly (ethylene / butylene) block-polystyrene)], and styrene-isoprene. Copolymers (polystyrene-polyisoprene block-polystyrene), styrene-propylene-based copolymers [SEP (polystyrene- (ethylene / propylene) block), SEPS (polystyrene-poly (ethylene / propylene) block-polystyrene), SEEPS ( Polystyrene-poly (polystyrene-ethylene / propylene) block-polystyrene), SEB (polystyrene (ethylene / butylene) block)] and the like can be mentioned.

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

-Polyurethane-based thermoplastic elastomer-
As the polyurethane-based thermoplastic elastomer, for example, at least polyurethane forms a hard segment in which pseudo-crosslinks are formed by physical aggregation, and other polymers form a soft segment which is amorphous and has a low glass transition temperature. Examples of materials are available.
Specific examples of the polyurethane-based thermoplastic elastomer include the polyurethane-based thermoplastic elastomer (TPU) specified in JIS K6418: 2007. The polyurethane-based thermoplastic elastomer can be represented as a copolymer containing a soft segment containing a unit structure represented by the following formula A and a hard segment containing 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 adibate) diol, poly-ε-caprolactone diol, and poly (hexamethylene carbonate) having a molecular weight within the above range. ) Diol, ABA type triblock polyether and the like.
These can be used alone or in combination of two or more.

In formulas A and B, R is a partial structure introduced using a diisocyanate compound containing an aliphatic hydrocarbon represented by R, an alicyclic hydrocarbon, or an aromatic hydrocarbon. 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-cyclohexanediisocyanate and 4,4-cyclohexanediisocyanate. Further, examples of the aromatic diisocyanate compound containing an aromatic hydrocarbon represented by R include 4,4'-diphenylmethane diisocyanate and tolylene diisocyanate.
These can be used alone or in combination of two or more.

In the formula B, as the short-chain aliphatic hydrocarbon represented by P', the alicyclic hydrocarbon, or the aromatic hydrocarbon, for example, those having a molecular weight of less than 500 can be used. Further, P'is derived from a diol compound containing a short-chain aliphatic hydrocarbon represented by P', an alicyclic hydrocarbon, or an aromatic hydrocarbon. Examples of the aliphatic diol compound containing a short-chain aliphatic hydrocarbon represented by P'include glycols and polyalkylene glycols, 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- Examples thereof include decanediol.
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, and the like. Cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol and the like can be mentioned.
Further, 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'-dihydroxydiphenylsulfide, 4,4'-dihydroxydiphenylsulfone, 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-dihydroxynaphthalin, and 2,6-dihydroxynaphthalin.
These can be used alone or in combination of two or more.

The number average molecular weight of the polymer (specifically polyurethane) forming the hard segment 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 20000, more preferably 500 to 5000, and particularly preferably 500 to 3000, from the viewpoint of 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 polyurethane-based thermoplastic elastomer can be synthesized by copolymerizing a polymer forming a hard segment and a polymer forming a soft segment by a known method. As the polyurethane-based thermoplastic elastomer, for example, the thermoplastic polyurethane described in JP-A-5-331256 can be used.
As the polyurethane-based thermoplastic elastomer, specifically, a combination of a hard segment composed of an aromatic diol and an aromatic diisocyanate and a soft segment composed of a polycarbonate ester is preferable, and more specifically, tolylene diisocyanate (more specifically, tolylene diisocyanate ( TDI) / polyester-based polyol copolymer, TDI / polyether-based polyol copolymer, TDI / caprolactone-based polyol copolymer, TDI / polycarbonate-based polyol copolymer, 4,4'-diphenylmethane diisocyanate (MDI) / polyester Select from the group consisting of based polyol copolymers, MDI / polyether polyol copolymers, MDI / caprolactone-based polyol copolymers, MDI / polycarbonate-based polyol copolymers, and MDI + hydroquinone / polyhexamethylene carbonate copolymers. At least one of them is more preferable, TDI / polyester-based polyol copolymer, TDI / polyether-based polyol copolymer, MDI / polyester polyol copolymer, MDI / polyether-based polyol copolymer, and MDI + hydroquinone /. At least one selected from the group consisting of polyhexamethylene carbonate copolymers is more preferable.

Commercially available products of polyurethane-based thermoplastic elastomers include, for example, the "Elastran" series manufactured by BASF (for example, ET680, ET880, ET690, ET890, etc.) and the "Chramiron U" series manufactured by Kuraray Co., Ltd. (for example,). 2000 series, 3000 series, 8000 series, 9000 series, etc.), "Milactran" series manufactured by Nippon Miractran Co., Ltd. (for example, XN-2001, XN-2004, P390RSUP, P480RSUI, P26MRNAT, E490, E590, P890, etc.) Can be used.

-Olefin-based thermoplastic elastomer-
As the olefin-based thermoplastic elastomer, for example, at least a polyolefin forms a crystalline hard segment having a high melting point, and another polymer (for example, a polyolefin different from the polyolefin forming the hard segment, a polyvinyl compound, etc.) is amorphous. Examples of the material forming a soft segment having a low glass transition temperature. 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 an olefin-α-olefin random copolymer, an olefin block copolymer, and the like, and specific examples thereof include a propylene block copolymer, an ethylene-propylene copolymer, and a propylene-. 1-hexene copolymer, propylene-4-methyl-1pentene 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-methacrylate 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-methacrylate copolymer, propylene-methyl methacrylate copolymer Copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer, propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, ethylene-vinyl acetate Examples thereof include a copolymer and a propylene-vinyl acetate copolymer.

Among these, as the olefin-based thermoplastic elastomer, a propylene block copolymer, an ethylene-propylene copolymer, a propylene-1-hexene copolymer, a propylene-4-methyl-1pentene copolymer, and a 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-methacrylate copolymer , Propropylene-methyl methacrylate copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer, propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer At least one selected from the group consisting of a coalescence, an ethylene-vinyl acetate copolymer, and a propylene-vinyl acetate copolymer is preferable, and an ethylene-propylene copolymer, a propylene-1-butene copolymer, and an ethylene-1 are preferable. At least one selected from the group consisting of a-butene copolymer, an ethylene-methyl methacrylate copolymer, an ethylene-methyl acrylate copolymer, an ethylene-ethyl acrylate copolymer, and an ethylene-butyl acrylate copolymer. More preferred.
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 5000 to 10000000. When the number average molecular weight of the olefin-based thermoplastic elastomer is 5000 to 1000000, the mechanical properties of the thermoplastic resin material are sufficient, and the processability is also excellent. From the same viewpoint, the number average molecular weight of the olefin-based thermoplastic elastomer is more preferably 7,000 to 1,000,000, and particularly preferably 000 to 1,000,000. Thereby, the mechanical physical characteristics 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 copolymerizing by a known method.

Further, as the olefin-based thermoplastic elastomer, one obtained by acid-modifying the thermoplastic elastomer may be used.
"The product obtained by acid-modifying an olefin-based thermoplastic elastomer" means that an unsaturated compound having an acidic group such as a carboxylic acid group, a sulfate 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, or a phosphoric acid group to an olefin-based thermoplastic elastomer, for example, as an unsaturated compound having an acidic group to an olefin-based thermoplastic elastomer. It is possible to bond (for example, graft polymerization) an unsaturated bond site of an unsaturated carboxylic acid (generally, maleic anhydride).
As the unsaturated compound having an acidic group, an unsaturated compound having a carboxylic acid group which is a weak acid group is preferable from the viewpoint of suppressing deterioration of the olefin-based thermoplastic elastomer, and for example, acrylic acid, methacrylic acid, itaconic acid, and crotonic acid. Acids, isocrotonic acid, maleic acid and the like can be mentioned.

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

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

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 an ester-forming derivative thereof 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, diphenoxyetanedicarboxylic acid, 5 -Dicarboxylic acid components such as sulfoisophthalic acid or ester-forming derivatives thereof and diols having a molecular weight of 300 or less (for example, ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, decamethylene glycol, etc.) Aromatic diols; 1,4-cyclohexanedimethanol, alicyclic diols such as tricyclodecanedimethylol; xylylene glycol, bis (p-hydroxy) diphenyl, bis (p-hydroxyphenyl) propane, 2,2- Bis [4- (2-hydroxyethoxy) phenyl] propane, bis [4- (2-hydroxy) phenyl] sulfone, 1,1-bis [4- (2-hydroxyethoxy) phenyl] cyclohexane, 4,4'- Aromatic diols such as dihydroxy-p-terphenyl and 4,4'-dihydroxy-p-quarterphenyl; etc.) and polyesters derived from them, or a combination of two or more of these dicarboxylic acid components and diol components. It may be a polymerized polyester. It is also possible to copolymerize a trifunctional or higher functional polyfunctional carboxylic acid component, a polyfunctional oxyic acid component, a polyfunctional hydroxy component and the like in a range of 5 mol% or less.
Examples of the polyester forming the hard segment include polyethylene terephthalate, polybutylene terephthalate, polymethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and the like, and polybutylene terephthalate is preferable.

Examples of the polymer forming the soft segment include aliphatic polyesters and aliphatic polyethers.
Examples of the aliphatic polyether include poly (ethylene oxide) glycol, poly (propylene oxide) glycol, poly (tetramethylene oxide) glycol, poly (hexamethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, and poly (propylene oxide). ) Glycol ethylene oxide addition polymer, copolymer of ethylene oxide and tetrahydrofuran, etc. can be mentioned.
Examples of the aliphatic polyester include poly (ε-caprolactone), polyenant lactone, polycaprilolactone, polybutylene adipate, polyethylene adipate and the like.
Among these aliphatic polyethers and aliphatic polyesters, poly (tetramethylene oxide) glycol and poly (propylene oxide) glycol are examples of polymers that form soft segments 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, more preferably 98: 2 to 30:70 from the viewpoint of moldability. ..

Examples of the combination of the above-mentioned hard segment and the soft segment include the respective combinations of the above-mentioned hard segment and the soft segment. Among these, as the combination of the above-mentioned hard segment and soft segment, a combination in which the hard segment is polybutylene terephthalate and the soft segment is an aliphatic polyether is preferable, and the hard segment is polybutylene terephthalate and the soft segment. More preferably, the combination is poly (ethylene oxide) glycol.

Commercially available polyester-based thermoplastic elastomers include, for example, the "Hytrel" series manufactured by Toray DuPont Co., Ltd. (for example, 3046, 5557, 6347, 4047N, 4767N, etc.) and the "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.

-The thermoplastic resin The resin composition may contain a thermoplastic resin.
Examples of the thermoplastic resin include polyamide-based thermoplastic resin, polyester-based thermoplastic resin, olefin-based thermoplastic resin, polyurethane-based thermoplastic resin, vinyl chloride-based thermoplastic resin, and polystyrene-based thermoplastic resin. can.
Among the above, the thermoplastic resin is preferably at least one type of thermoplastic resin selected from the group consisting of a polyamide-based thermoplastic resin, a polyester-based thermoplastic resin, and an olefin-based thermoplastic resin. The thermoplastic resin may be used alone or in combination of two or more.

-Polyamide-based thermoplastic resin-
Examples of the polyamide-based thermoplastic resin include polyamides that form hard segments of the above-mentioned polyamide-based thermoplastic elastomers. Specific examples of the polyamide-based thermoplastic resin include a polyamide obtained by ring-opening polycondensation of ε-caprolactam (amide 6), a polyamide obtained by ring-opening polycondensation of undecanlactam (amide 11), and a 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, the "UBE nylon" series (for example, 1022B, 1011FB, etc.) manufactured by Ube Industries, Ltd. can be used. As a commercially available product of amide 11, for example, the "Rilsan B" series manufactured by Arkema Co., Ltd. can be used. As a commercially available product of amide 12, for example, the "UBE nylon" series manufactured by Ube Industries, Ltd. (for example, 3024U, 3020U, 3014U, etc.) can be used. As a commercially available product of amide 66, for example, the "Leona" series manufactured by Asahi Kasei Corporation (for example, 1300S, 1700S, etc.) can be used. As a commercially available product of amide MX, for example, the "MX nylon" series manufactured by Mitsubishi Gas Chemical Company, Inc. (for example, S6001, S6021, S6011, etc.) can be used.

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

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

Commercially available polyester-based thermoplastic resins include, for example, the "Juranex" series manufactured by Polyplastics Co., Ltd. (for example, 2000, 2002, etc.) and the "Novaduran" series manufactured by Mitsubishi Engineerings Plastics Co., Ltd. (for example, 5010R5, etc.). 5010R3-2, etc.), "Trecon" series manufactured by Toray Industries, Inc. (for example, 1401X06, 1401X31, etc.) and the like can be used.

-Olefin-based thermoplastic resin-
Examples of the olefin-based thermoplastic resin include polyolefins that form the hard segments of the above-mentioned olefin-based thermoplastic elastomer.
Specific examples of the olefin-based thermoplastic resin include polyethylene-based thermoplastic resins, polypropylene-based thermoplastic resins, and polybutadiene-based thermoplastic resins. Among these, polypropylene-based thermoplastic resin is 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 homopolymers, propylene-α-olefin random copolymers, propylene-α-olefin block copolymers, 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, and the like. 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, the thermoplastic elastomer may be used alone or in combination of two or more kinds of thermoplastic elastomers, or one or more kinds of thermoplastic elastomers and one or more kinds of thermoplastics may be used. 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.), anti-aging agents, oils, plasticizers, color formers, weather resistant agents, and the like.

(Physical characteristics of the 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, it is preferably 10 μm or more and 1000 μm or less, and more preferably 50 μm or more and 700 μm or less.

For the average thickness of the coating resin layer, an SEM image of a cross section obtained by cutting the bead core along the stacking direction of the bead wire, the coating resin layer, and the adhesive layer used as needed is obtained from any five locations. It is a number average value of the thickness of the coating resin layer measured from the obtained SEM image or the image obtained by the video microscope. The thickness of the coating resin layer in each SEM image is a value measured at the portion having the smallest thickness (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 the minimum).

-Tension elastic modulus The tensile elastic modulus of the coated 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 ride comfort during normal running. It is preferably 50 MPa or more and 700 MPa or less, and more preferably. 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 coated resin layer can be controlled by, for example, the type of resin contained in the coated resin layer. The tensile elastic modulus of the coating resin layer is measured in accordance with 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 contained in the bead core, for example, a measurement sample of the same material as the coating resin layer may be separately prepared and the tensile elastic modulus may be measured.

・ Melt flow rate (MFR)
The upper limit of the melt flow rate (MFR) of the coating resin layer is 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 preferred. When the MFR of the coating resin layer is 0.5 g / 10 min or more, molding corresponding to extrusion of a complicated shape in extrusion molding becomes possible.
The upper and lower limits 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 sample for measurement from the coating resin layer. The measuring method conforms to JIS-K7210-1 (2014). Specifically, MFR is performed using a melt indexer (for example, model number 2AC, Toyo Seiki Seisakusho Co., Ltd.). The measurement conditions are a temperature of 260 ° C., a load of 2.16 kg, an interval of 25 mm, and an orifice of 2.09Φ × 8L (mm) to determine the MFR.

As a method for setting 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, a thermoplastic elastomer having an MFR within the above range is used as the resin material; The type, amount, etc. of the resin and the additive may be adjusted so that the MFR is within the above range.

-Weight average molecular weight (Mw)
The weight average molecular weight Mw (converted to polymethyl methacrylate) of the resin contained in the coating resin layer is 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 44,000 or more, excellent fatigue durability is exhibited in the coated resin layer.
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, molding corresponding to extrusion of a complicated shape in extrusion molding becomes possible.
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 coated resin layer is measured by the following method after cutting out a sample for measurement from the coated resin layer.
For the weight average molecular weight, gel permeation chromatography (also referred to as "GPC") is performed using model number: HLC-8320GPC, manufactured by Tosoh Corporation. The measurement conditions were 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 velocity: 1 ml / min. The weight average molecular weight in terms of polymethyl methacrylate (PMMA) is determined using an RI detector.

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

-Bridge density The side reinforcing rubber preferably has a cross-linking density of 5 × 10 ^-4 mol / ml or more and 10 × 10 ^-4 mol / ml or less, preferably 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 amount and type of the vulcanizing agent, the vulcanization accelerator, and the like.

The crosslink density is measured as the total network density by a swelling compression method using Flory's theoretical formula (see, for example, Journal of the Japan Rubber Association, Vol. 63, No. 7, 1990, pp. 440-448).

The rubber composition is kneaded using a kneader such as a Banbury mixer, a roll, or an internal mixer, molded, and then vulcanized to be used as a side reinforcing rubber layer for 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-based synthetic rubber include styrene-butadiene copolymer (SBR), polybutadiene (BR), polyisoprene (IR), styrene-isoprene copolymer (SIR), butyl rubber (IIR), butyl halide rubber, and ethylene. Examples include -propylene-diene ternary copolymer (EPDM) and mixtures thereof.
The diene-based synthetic rubber is a diene-based synthetic rubber in which a part or all of the diene-based synthetic rubber has a branched structure by using a polyfunctional modifier, for example, a modifier such as tin tetrachloride. It is more preferable to have.

Examples of the rubber include those containing an amine-modified conjugated diene-based polymer obtained by modifying the conjugated diene-based polymer with an amine.
The content of the amine-modified conjugated diene polymer is preferably 30% by mass or more, particularly preferably 50% by mass or more, based on the total amount of the rubber.
When an amine-modified conjugated diene polymer is contained in an amount of 30% by mass or more, the obtained rubber composition tends to have a low heat generation, and therefore, it is considered that the 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 protonic amino group or an amino group protected by a desorbable group is introduced into the molecule as a functional group for modification. It is preferable to have.
The amine-modified conjugated diene-based polymer is preferably a conjugated diene-based polymer in which a functional group containing a silicon atom is further introduced as a modification functional group in addition to the amine-based 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 modification functional group may be present at any of the polymerization initiation terminal, side chain and polymerization active end of the conjugated diene polymer, but in the present embodiment, the modification functional group is present at the polymerization terminal. Is preferable, and it is more preferable that it is present at the same polymerization active terminal.

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 by the removable group include an N, N-bis (trihydrocarbylsilyl) amino group, an N- (trihydrocarbylsilyl) imino group and the like. Among the above, the amino group protected by the desorbable group may be 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. It is preferably a hydrocarbyl group containing a trimethylsilyl group, more preferably.
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 by the removable group include an N- (trimethylsilyl) imino group and the like. The group containing the 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, the protection obtained by reacting the active terminal of the conjugated diene polymer with a protected primary amine compound. It is preferably a primary amine-modified conjugated diene polymer modified with a chemical primary amino group.

The conjugated diene-based 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, 1,3-hexadiene and the like. Therefore, 1,3-butadiene is preferable. The conjugated diene compound 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 compound may be used alone or in combination of two or more.
The conjugated diene-based polymer is preferably polybutadiene or a styrene-butadiene copolymer, and more preferably polybutadiene.

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

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

As the organic alkali metal compound, an organic lithium compound such as hydrocarbyl lithium such as n-butyl lithium; a lithium amide compound such as lithium hexamethyleneimide and lithium pyrrolidide is preferable. For example, when hydrocarbyl lithium is used as an 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 a lithium amide compound is used as an 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 conventionally known methods such as JP-A-2011-68342 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, more preferably 30 to 100.

The ratio (Mw / Mn) of the weight average molecular weight (Mw) to 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, more preferably 150,000 to 300,000.

The content of the 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.

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

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 oxides, hydroxides, hydrates or carbonates of the metals. Represents.
In general formula (I), n represents an integer of 1-5. 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, SAF grade and the like can be used alone or in combination.
Among the above, 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 admixture.

As the inorganic filler represented by the general formula (I), it is preferable that M is at least one selected from the group consisting of aluminum metals 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 gibsite, bayarite, etc .; 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); Al 2 SiO 5, Al 4 · 3SiO 4 · 5H 2 O-such as Aluminum silicate; _{Magnesium silicate such as Mg 2} SiO ₄ , MgSiO ₃ ; Calcium silicate such as Ca ₂ · SiO ₄ ; Calcium silicate such as Al ₂ O ₃ · CaO · 2SiO ₂ ; Calcium magnesium 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 aluminosilicate such as zeolite Salt; etc. can be used.

The rubber composition contains various additives such as vulcanizing agent, vulcanization accelerator, process oil, antiaging agent, scorch inhibitor, zinc oxide, stearic acid and the like, as long as the effects of the present embodiment are not impaired. May include.

The content of the filler is described above from the viewpoint of enhancing the dispersibility of the filler in the rubber composition, suppressing the heat generation of the tire and the decrease in the elastic coefficient of the rubber, and improving the riding comfort during normal driving. 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 with respect to 100% by mass of the rubber.

[Carcass]
In the present embodiment, the "carcass" is a member forming the skeleton of a conventional tire, and includes so-called radial carcass, bias carcass, semi-radial carcass and the like. Carcass generally has a structure in which reinforcing materials such as cords and fibers are coated with a rubber material.

-Rubber material The rubber material may contain at least rubber, and may contain other components such as additives as long as the effects according to the present embodiment are not impaired. However, the content of rubber in the rubber material is preferably 50% by mass or more, 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 blends can be used alone or in combination of two or more. For example, the rubbers shown below, or a blend of two or more of these rubbers can be used.
The natural rubber may be a sheet rubber or a 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, modified rubbers, and the like can be used. Specifically, for example, butadiene-based polymers such as polybutadiene (BR), a copolymer of butadiene and an aromatic vinyl compound (for example, SBR, NBR, etc.), and a copolymer of butadiene and another diene-based compound; Isoprene-based polymers such as polyisoprene (IR), copolymers of isoprene and aromatic vinyl compounds, and copolymers of isoprene and other diene-based 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 blends thereof; and the like.

Further, as the rubber material used for the carcass, other components such as additives may be added 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 blended. can do.

The carcass formed of the rubber material is obtained by vulcanizing the unvulcanized rubber material by heating.

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

As the rubber material, a material used in a normal rubber tire can be used, and the material is not particularly limited.

[Bead filler]
The tire according to the present embodiment may have a bead filler extending outward in the tire radial direction from the coating resin layer at the bead portion. Further, the bead filler may be an identical member integrally molded 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 present embodiment described above are also used. Further, the preferred resin type, preferred content, other components that may be contained, and the like are the same as those of the coating resin layer.

[Method of forming the bead part]
Here, a method of forming a bead portion in a 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 Coating 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 coated with the adhesive layer 112, and then the strip member formed by coating the three bead wires 111 coated with the adhesive layer 112 with the first coating resin layer 113 is formed. Further, the bead core 101 is formed by winding the strip member and laminating the strip members having a substantially rectangular shape in cross section in three stages.

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

In the present embodiment, a material (for example, an adhesive) for forming the molten adhesive layer 112 is coated on the outer peripheral surface of the bead wire 111, and a first coated resin layer in the molten state is further coated on the surface of the material forming the adhesive layer 112. A strip member is formed by coating a material (that is, a resin composition) forming 113 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 substantially rectangular 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 a known method, and examples thereof include a method such as extrusion molding. The bead core 101 can be formed by winding and stacking strip members, and the strip members can be joined to each other while melting the first coating resin layer 113 by a known method such as hot plate welding. This can be done by winding and solidifying the melted first coating resin layer 113. Alternatively, the steps can be joined by adhering the steps with an adhesive or the like.

-Formation of the second coated resin layer Next, the surface of the obtained bead core 101 is coated with a material (for example, resin) for forming the second coated resin layer 114 in a molten state, and is solidified by cooling to obtain a second coating resin layer. The coating resin layer 114 is formed. The second coating resin layer 114 can be formed by a known method, and examples thereof include a method such as injection molding.
Specifically, the bead core 101 is arranged in the cavity of the injection molding die, and the material forming the second coated resin layer 114 in the molten state 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 outside of the second coating resin layer 114 in the tire radial direction. The bead filler 103 can be formed by a known method. For example, when the bead filler 103 is formed of a resin, a method such as injection molding can be mentioned. When the bead filler 103 is a member of the same body integrally molded with the second coating resin layer 114, once using an injection molding die processed into the shape of the bead filler 103 and the second coating resin layer 114. Both members can be integrally molded by injection of.

As described above, according to the present disclosure, the following run-flat tires are provided.
[1] A bead core having a bead wire and a coating resin layer formed by coating the bead wire and a resin composition, and a bead core.
Side reinforcing rubber provided on the tire side and formed by the rubber composition,
With
The resin composition contains a thermoplastic elastomer and contains
The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.
Run-flat tires.
[2] The run-flat tire according to the above [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 run-flat tire according to the above [1] or [2], wherein the coating resin layer has a tensile elastic modulus of 50 MPa or more and 1000 MPa or less.

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

[5] The run-flat 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 [1] to [5] above, 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 tire.

Hereinafter, the present disclosure will be described in more detail based on Examples, but the present disclosure is not limited to the following Examples. The materials, amounts used, ratios, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present embodiment. Unless otherwise specified, "part" represents a mass standard.

(Preparation of rubber composition for side reinforcing rubber)
The rubber composition for side reinforcing rubber having the formulation shown in Table 1 is prepared and kneaded with a Banbury mixer of MIXTRON BB MIXER manufactured by Kobe Steel, Ltd. to form 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, manufactured by Asahi Carbon Co., Ltd., N550.
-Anti-aging agent: Hexamethylenetetramine.
-Vulcanization accelerator 1: Thiram compound, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., Noxeller TOT-N.
-Vulcanization accelerator 2: Noxeller NS-P, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Synthetic rubber synthesis example: Polybutadiene rubber)
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 into a nitrogen-substituted 5 L autoclave, and 2.85 mmol of n was injected therein. After adding −butyllithium (BuLi), polymerization is carried out for 4.5 hours in a warm water bath at 50 ° C. equipped with a stirrer. The reaction conversion rate 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, desolvated by steam stripping, and dried on a roll at 110 ° C. To obtain polybutadiene. The polybutadiene has a microstructure (that is, a 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 kept at a temperature of 50 ° C. without deactivating the polymerization catalyst, and 1129 mg of N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane (that is, 3) in which the primary amino group was protected. .364 mmol) is added and the modification reaction is carried out for 15 minutes. Finally, 2,6-di-tert-butyl-p-cresol is added to the polymer solution after the reaction. The primary amino group, which has been desolvated and protected by steam stripping, is then deprotected, and the rubber is dried by a heat 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 and 2, Comparative Examples 5 and 6]
(Manufacturing of resin bead members)
Maleic anhydride-modified polyester thermoplastic elastomer "Primaloy-AP GQ730" manufactured by Mitsubishi Chemical Co., Ltd. as an adhesive on the surface of monofilament (monofilament with an average diameter of φ1.25 mm, made of steel, strong: 2700 N, elongation 7%). Is extruded and adhered by an extruder in a state of being heated and melted. The Primaloy-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, a polyester-based thermoplastic elastomer (specifically, manufactured by Toray DuPont Co., Ltd., trade name "Hitrel 5557") was placed in a mold so that three bead wire samples to which adhesive was attached were arranged side by side. , Extruded with an extruder, adhered to the surface of the adhesive, coated and cooled to form the first coated resin layer. The extrusion conditions for the polyester-based thermoplastic elastomer are such that the temperature of the resin is 240 ° C. A member in which three bead wires formed in this manner are lined up is wound while being welded with hot air. As a result, a bead core having a structure in which each of the nine bead wires is coated with an adhesive layer and the periphery thereof is coated with a 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 from the above was placed in a mold pre-processed into the shape of a member in which the second coating resin layer and the bead filler were integrated, and a polyester-based thermoplastic elastomer (specifically, Toray DuPont Co., Ltd.) was installed. Manufactured by, trade name "Hitrel 5557") is injected by an injection molding machine. As a result, a bead member having a structure (that is, a structure shown in FIG. 6) 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 is produced. The mold temperature at the time of injection molding is 100 ° C., and the molding temperature is 240 ° C.

(Making run-flat tires)
Unvulcanized carcass and belt layers are made according to the above embodiments. The belt layer is installed on the outer peripheral surface of the unvulcanized carcass, the unvulcanized tread is wrapped around the outer periphery of the belt layer, and the side reinforcing rubber composed of the rubber compositions shown in Tables 1 and 2 is prepared as described above. Obtain a raw tire in combination with a bead member made of. 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.
Table 2 shows the results of 1% tensile modulus, 50% modulus, and 100% modulus of the rubber composition for side reinforcing rubber measured by the above-mentioned measuring method.

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

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

-Evaluation-
(Ride quality during normal driving)
The vertical spring constant is measured when the internal pressure of the tires of each example is 230 kPa.
The evaluation is an exponential notation in which the measured value of Comparative Example 1 is 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 the indoor drum test based on the ISO standard, run flat running is performed at an internal pressure of 0 kPa and a speed of 80 km / h. The mileage until the vehicle becomes impossible to travel due to a tire failure or a support failure is measured, and an index is obtained when the mileage in Comparative Example 1 is 100. The results are shown in Table 2. The larger the index, the better the run-flat running performance (that is, durability).

Each rubber composition A to D shown in Table 1 is a synthetic material.
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, the second embodiment is the prediction data by the simulation.

From the above results, it can be seen that the run-flat tires of the examples have better ride comfort and run-flat running durability during normal running than the run-flat tires of the comparative example.

The disclosure of Japanese Patent Application No. 2018-21115, filed November 9, 2018, is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated 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 portion 111 Bead wire 112 Adhesive layer 113 First coating resin layer 114 Second coating resin layer

Claims (6)

A bead core having a bead wire and a coating resin layer covering the bead wire and formed of a resin composition, and a bead core.
Side reinforcing rubber provided on the tire side and formed by the rubber composition,
With
The resin composition contains a thermoplastic elastomer and contains
The 1% tensile elastic modulus of the side reinforcing rubber is 8 MPa or less, and the 100% modulus is 10 MPa or more.
Run-flat tires. 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 coating resin layer has a tensile elastic modulus of 50 MPa or more and 1000 MPa or less. The run-flat 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.}

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