JP6408937B2 - Airless tire - Google Patents

Description

  The present invention relates to an airless tire having reduced rolling resistance while ensuring excellent steering stability performance.

  Known as an airless tire is a structure in which a cylindrical tread ring having a ground contact surface and a hub fixed to an axle are connected by a plurality of spoke plate portions arranged radially (for example, a patent) Reference 1).

  In such an airless tire, it is advantageous from the viewpoint of strength, durability, steering stability, grip properties, and the like to use a rubber material of a normal pneumatic tire for a tread rubber layer forming a ground contact surface of the tread ring. It is. However, in an airless tire, a load and an impact are received by the tread ring and the spoke plate portion in place of the filling internal pressure in the pneumatic tire, so that the degree of deformation is larger than that of the pneumatic tire. Therefore, the rigidity and heat generation of the composition constituting the tread ring have a great influence on the rolling resistance and the ride comfort performance.

  From such a point of view, a rubber member other than the tread rubber layer in the tread ring is desired to have higher elasticity and lower heat generation than the rubber member used for the pneumatic tire. However, conventional rubber materials for pneumatic tires tend to have high heat generation if they are made highly elastic, and it has been difficult to make a major improvement.

JP 2008-260514 A

  Therefore, the present invention is based on the use of a rubber composition containing butadiene rubber, α, β-unsaturated carboxylic acid metal salt, and peroxide for the reinforcing rubber layer of the tread ring, and has high elasticity and low fuel consumption. It is an object to provide an airless tire that can reduce the rolling resistance while ensuring excellent steering stability performance.

The present invention provides an airless comprising a cylindrical tread ring having a grounding surface, a hub that is arranged radially inside the tread ring and fixed to an axle, and a spoke that connects the tread ring and the hub. Tire,
The tread ring includes a tread rubber layer that constitutes a ground contact surface, and a reinforcing rubber layer that is disposed inside the tire radius of the tread rubber layer.
The reinforcing rubber layer contains 10 to 80 parts by weight of an α, β-unsaturated carboxylic acid metal salt with respect to 100 parts by weight of a rubber component having a butadiene rubber content of 10 to 100% by weight, and is peroxidized. It is characterized by comprising a rubber composition containing a product.

  In the airless tire according to the present invention, the tread ring includes an outer reinforcing cord layer provided closest to the tread rubber layer, and an inner reinforcing cord layer provided on the inner side in the tire radial direction of the outer reinforcing cord layer. It is preferable that the reinforcing rubber layer is disposed between the outer reinforcing cord layer and the inner reinforcing cord layer.

In the airless tire according to the present invention, the reinforcing rubber layer is 30 complex elastic modulus E * ₃₀ (Unit: MPa) at ℃ is a loss ratio of the tangent _{tanδ 30 (E * 30 / tanδ} 30) is more than 700 It is preferable.

In the airless tire according to the present invention, the outer reinforcing cord layer includes a first cord ply having a first reinforcing cord that is inclined with respect to the tire circumferential direction;
A second cord ply having a second reinforcing cord provided on the outer side in the tire radial direction of the first cord ply and inclined and arranged at the same angle and in the opposite direction to the first reinforcing cord with respect to the tire circumferential direction; Including
The inner reinforcing cord layer preferably includes a third cord ply having a third reinforcing cord arranged in parallel with the tire circumferential direction or the tire axial direction.

In the present application, the complex elastic modulus E * ₃₀ and loss tangent tan δ ₃₀ are measured using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) at a temperature of 30 ° C., a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ± It is a value measured under the condition of 1%.

  As described above, the airless tire of the present invention uses a rubber composition containing butadiene rubber, an α, β-unsaturated carboxylic acid metal salt and a peroxide in the reinforcing rubber layer in the tread ring. In this rubber composition, a butadiene rubber and an unsaturated carboxylic acid metal salt can be co-crosslinked using a peroxide as an initiator to obtain physical properties excellent in elasticity and fuel efficiency. Thereby, in an airless tire, it is possible to reduce rolling resistance while ensuring excellent steering stability performance.

  The rubber composition tends to be inferior to a normal pneumatic tire rubber member in terms of stretchability and tensile strength. However, when the reinforcing rubber layer made of this rubber composition has a so-called sandwich structure arranged between the outer reinforcing cord layer and the inner reinforcing cord layer, the problems of stretchability and tensile strength can be solved.

1 is a perspective view showing an embodiment of an airless tire of the present invention. It is a perspective view which shows the tread ring of FIG. It is sectional drawing of the tread ring of FIG. It is a perspective view which shows the modification of the inner side reinforcement cord layer of FIG. It is a perspective view which shows the modification of the outer side reinforcement cord layer of FIG. It is a perspective view which shows another modification of the outer side reinforcement cord layer of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an airless tire 1 according to the present embodiment includes a cylindrical tread ring 2 having a ground contact surface 21, a hub 3 that is arranged radially inside the tread ring 2 and is fixed to an axle, A spoke 4 for connecting the tread ring 2 and the hub 3 is provided. In this example, the case where the airless tire 1 is formed as a tire for a passenger car is shown.

  The hub 3 has a disk part 31 fixed to the axle and a cylindrical part 32 formed on the outer periphery of the disk part 31. The hub 3 can be formed of a metal material such as steel, an aluminum alloy, and a magnesium alloy, for example, similarly to the conventional tire wheel.

  The spoke 4 is formed by a cast molded body made of a polymer material. The spokes 4 have a plate shape and are provided in a plurality in the tire circumferential direction.

  As shown in FIGS. 2 and 3, the tread ring 2 includes a tread rubber layer 22 that constitutes the ground contact surface 21, and a reinforcing rubber layer 7 that is disposed inside the tire radius. In this example, the tread ring 2 further includes an outer reinforcing cord layer 5 provided closest to the tread rubber layer 22 and an inner reinforcing cord layer 6 provided inside the outer reinforcing cord layer 5 in the tire radial direction. In addition, the reinforcing rubber layer 7 is disposed between the outer reinforcing cord layer 5 and the inner reinforcing cord layer 6. That is, a sandwich structure is formed in which both sides of the reinforcing rubber layer 7 are sandwiched between the outer reinforcing cord layer 5 and the inner reinforcing cord layer 6.

  Tread grooves (not shown) are formed in various pattern shapes on the ground contact surface 21 which is the outer peripheral surface of the tread ring 2 in order to provide wet performance. For the tread rubber layer 22, a rubber composition excellent in frictional force against grounding and wear resistance is suitably employed.

  In this example, since the number of outer reinforcing cord layers 5 is greater than the number of inner inner reinforcing cord layers 6, the rigidity of the ground plane 21 can be easily increased. Conversely, the number of layers of the inner reinforcing cord layer 6 is smaller than the number of layers of the outer reinforcing cord layer 5, whereby the weight can be easily reduced.

  The outer reinforcing cord layer 5 includes a first cord ply 51 and a second cord ply 52 provided outside the first cord ply 51 in the tire radial direction.

  In this example, the width of the first cord ply 51 and the width of the second cord ply 52 are set to be approximately equal in the tire axial direction. The term “substantially equal” includes the case where the width of the first cord ply 51 and the width of the second cord ply 52 match, and the case where each width is different within a range of 10 mm or less.

  The first cord ply 51 includes a first reinforcing cord 56 that is inclined with respect to the tire circumferential direction at an angle θ. The first reinforcing cord 56 is covered with a topping rubber.

  The second cord ply 52 has a second reinforcement cord 57 that is inclined and arranged at the same angle θ and in the opposite direction as the first reinforcement cord 56 with respect to the tire circumferential direction. The second reinforcing cord 57 is covered with a topping rubber.

  As the 1st reinforcement cord 56 and the 2nd reinforcement cord 57, the material equivalent to the belt cord of a pneumatic tire, for example, a steel cord, can be adopted suitably. However, for example, high modulus organic fiber cords such as aramid, polyethylene naphthalate (PEN), and polyethylene terephthalate (PET) having high strength and elastic modulus can be used as required.

  The first reinforcing cord 56 and the second reinforcing cord 57 are inclined and arranged in directions opposite to each other with respect to the tire circumferential direction, whereby the rigidity of the outer reinforcing cord layer 5 is increased and the tread ring 2 can be effectively used. Reinforce to. Further, the outer reinforcing cord layer 5 exhibits high resistance to in-plane torsion and generates cornering power, like the belt cord reinforcing layer of a pneumatic tire, when a slip angle is imparted to the airless tire 1. Provides a good turning performance.

  The inner reinforcement cord layer 6 includes a third cord ply 61 having a third reinforcement cord 66. The third reinforcing cord 66 is covered with a topping rubber.

  The third reinforcing cords 66 in this example are arranged in parallel to the tire circumferential direction. Here, “parallel to the tire circumferential direction” means that the arrangement of the third reinforcing cords 66 is substantially parallel to the tire circumferential direction. In consideration of manufacturing tolerances, the tires of the third reinforcing cords 66 are arranged. The angle θ3 with respect to the circumferential direction is, for example, about 0 ° ± 5 °. As the third reinforcing cord 66, for example, a steel cord can be suitably used, but a high modulus organic fiber cord such as aramid, polyethylene naphthalate (PEN), polyethylene terephthalate (PET) can also be used as required.

  The rigidity of the tread ring 2 in the tire circumferential direction is enhanced by the third reinforcing cord 66 arranged in the inner reinforcing cord layer 6. Thereby, the shape of the contact surface 21 at the time of deceleration and acceleration is stabilized, and the braking performance and the traction performance are improved. Further, the third cord ply 61 having the third reinforcing cords 66 arranged in parallel to the tire circumferential direction can ensure symmetry with respect to the tire circumferential direction line while reducing the weight by a single layer.

  FIG. 4 shows another embodiment of the third cord ply 61. As shown in FIG. 4, the third reinforcing cords 66 may be arranged in parallel to the tire axial direction. Here, “parallel to the tire axial direction” means that the arrangement of the third reinforcing cords 66 is substantially parallel to the tire axial direction, and considering the manufacturing tolerance, the tire of the third reinforcing cord 66 The angle θ3 with respect to the circumferential direction is, for example, about 90 ° ± 5 °.

  The third reinforcing cord 66 arranged parallel to the tire axial direction increases the rigidity of the tread ring 2 in the tire axial direction. Thereby, when the big slip angle is provided to the airless tire 1, the shape of the contact surface 21 is stabilized, and the steering stability performance is improved. Further, the third cord ply 61 having the third reinforcing cords 66 arranged in parallel to the tire axial direction can ensure symmetry with respect to the tire circumferential direction line while reducing the weight by a single layer.

  Here, in the outer reinforcement cord layer 5 and the inner reinforcement cord layer 6, symmetry with respect to the tire circumferential direction line is important. If there is no symmetry, the tread ring 22 is deformed into a strain due to torsion by the outer reinforcing cord layer 5 and the inner reinforcing cord layer 6 at the time of loading, resulting in a difficulty in smooth rolling.

  In a pneumatic tire, in order to suppress expansion of a tread portion accompanying internal pressure filling, generally, an angle of a belt cord with respect to a tire circumferential direction is limited to a required range. On the other hand, in the airless tire 1 of the present embodiment, since it is not necessary to consider the internal pressure filling, the angle θ of the first and second reinforcing cords 56 and 57 is determined in a wide range. Specifically, the angle θ is preferably 5 ° to 85 °. When the angle θ is less than 5 °, the rigidity of the tread ring 2 in the tire axial direction is insufficient, which may adversely affect the turning performance. On the other hand, when the angle θ exceeds 85 °, the rigidity of the tread ring 2 in the tire circumferential direction is insufficient, which may adversely affect the straight running performance and the turning performance at a minute slip angle.

  In this example, the case where the 1st cord ply 51 is formed in the tire radial direction innermost side among the outer side reinforcement cord layers 5 is shown. However, it is also possible to provide at least one cord ply further inside the tire radial direction than the first cord ply 51. In this example, the case where the second cord ply 52 is formed on the outermost side in the tire radial direction of the outer reinforcing cord layer 5 is shown. However, the outer side in the tire radial direction further than the second cord ply 52 is shown. It is also possible to provide at least one cord ply. Since such a cord ply reinforces the tread ring 2 and improves the load carrying capacity of the airless tire 1, for example, it is suitably used for a tire having a large load such as a commercial vehicle tire.

  Specifically, in the embodiment of FIG. 5, the outer reinforcing cord layer 5 further includes a fourth cord ply 53 in which a fourth reinforcing cord 58 is arranged on the outer side in the tire radial direction of the second cord ply 52. Composed. In addition, the other structure which is not demonstrated in FIG. 5 is the same as that of previous embodiment.

  The fourth reinforcing cords 58 are arranged in parallel with the tire circumferential direction (that is, the angle θ4 with respect to the tire circumferential direction is 0 ° ± 5 ° as in the third reinforcing cord 66). Such a fourth reinforcing cord 58 increases the rigidity of the tread ring 2 in the tire circumferential direction. Thereby, the shape of the contact surface 21 at the time of deceleration and acceleration is stabilized, and the braking performance and the traction performance are improved. Further, the fourth cord ply 53 having the fourth reinforcing cords 58 arranged in parallel in the tire circumferential direction can ensure symmetry with respect to the tire circumferential line while reducing the weight by a single layer.

The elastic modulus E ₄ of the fourth reinforcing cord 58 is preferably equal to or lower than the elastic modulus E _{0 of} the first and second reinforcing cords 56 and 57. Modulus E ₄ of a fourth reinforcing cord 58, if it exceeds the elastic modulus E _0, causes a fourth cord ply 53 is a working ply, when the slip angle airless tire 1 has been applied, the cornering power is sufficient It cannot be generated and adversely affects the turning performance. For the fourth reinforcing cord 58, for example, an organic fiber such as nylon is suitably employed.

  FIG. 6 shows still another embodiment of the outer reinforcing cord layer 5. Other configurations not described here are the same as those in the previous embodiment. In the embodiment of FIG. 6, the outer reinforcing cord layer 5 further includes a fifth cord ply 54 in which a fifth reinforcing cord 59 is arranged on the inner side in the tire radial direction of the first cord ply 51.

  The fifth reinforcing cords 59 are arranged in parallel to the tire circumferential direction (that is, the angle θ5 with respect to the tire circumferential direction is 0 ° ± 5 ° as in the third reinforcing cord 66). Such a fifth reinforcing cord 59 increases the rigidity of the tread ring 2 in the tire circumferential direction. Thereby, the shape of the contact surface 21 at the time of deceleration and acceleration is stabilized, and the braking performance and the traction performance are improved. Further, the fifth cord layer 54 having the fifth reinforcing cords 59 arranged in parallel to the tire circumferential direction can ensure symmetry with respect to the tire circumferential direction line while reducing the weight by a single layer.

  A structure in which the embodiment of FIG. 5 and the embodiment of FIG. 6 are combined, that is, in the outer reinforcing cord layer 5, a fourth cord ply 53 is provided on the outer side in the tire radial direction of the second cord ply 52, and the first cord The fifth cord ply 54 can also be disposed on the inner side of the ply 51 in the tire radial direction.

  Next, in the tread ring 2, a sandwich structure is formed by the outer reinforcing cord layer 5, the inner reinforcing cord layer 6, and the reinforcing rubber layer 7 disposed therebetween. As a result, the tension and compression forces acting when the tread ring 2 receives a load can be supported on the outer reinforcing cord layer 5 and the inner reinforcing cord layer 6 on both sides of the reinforcing rubber layer 7. Can be suppressed.

  For this purpose, a reinforcing cord disposed on the innermost side in the tire radial direction among the reinforcing cords of the outer reinforcing cord layer 5 and a reinforcing cord disposed on the outermost side in the tire radial direction among the reinforcing cords on the inner reinforcing cord layer 6. The distance D in the tire radial direction (shown in FIG. 3) is preferably 3 mm or more. In particular, the thickness of the reinforcing rubber layer 7 is more preferably 3 mm or more.

  In addition, the following rubber composition (A) is used in order to sufficiently enhance the above-described functions to ensure better handling stability and to reduce rolling resistance.

  The rubber composition (A) contains 10 to 80 parts by weight of an α, β-unsaturated carboxylic acid metal salt with respect to 100 parts by weight of a rubber component having a butadiene rubber (BR) content of 10 to 100% by weight. Containing and containing peroxide. In this rubber composition (A), a butadiene rubber (BR) and a metal salt of α, β-unsaturated carboxylic acid are co-crosslinked using a peroxide as an initiator. High elasticity and low exothermic property, which were difficult, are achieved. In particular, by using the rubber composition (A) for the tread ring 2 of the airless tire 1, it is possible to provide a great effect on steering stability performance and rolling resistance.

  The rubber component contains 10 to 100% by mass of butadiene rubber (BR) in 100 parts by mass. When butadiene rubber (BR) is used by blending with other rubber, natural rubber (NR), styrene butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), styrene isoprene butadiene rubber are used as the rubber for blending. (SIBR), styrene isoprene rubber (SIR), epoxidized natural rubber (ENR) and the like can be mentioned, and these can be used alone or in combination of two or more. Among these, NR is preferable because it is excellent in low heat generation.

  The content of butadiene rubber (BR) is 10% by weight or more, preferably 20% by weight or more. If it is less than 10% by weight, the effect of reducing heat generation tends to decrease. Further, when the content of butadiene rubber (BR) is 100% by weight, the strength tends to decrease. Therefore, the upper limit of the content of butadiene rubber (BR) is preferably 90% by weight or less, more preferably 80% by weight or less. .

  As the co-crosslinking agent, α, β-unsaturated carboxylic acid metal salt which is a metal salt of α, β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and the like is employed. In particular, since it is excellent in durability, a metal salt of acrylic acid and / or a metal salt of methacrylic acid is preferable, and a metal salt of methacrylic acid is more preferable. Examples of the metal in the α, β-unsaturated carboxylic acid metal salt include zinc, sodium, magnesium, calcium, and aluminum, and zinc is preferable because sufficient hardness can be obtained.

  The content of the co-crosslinking agent (α, β-unsaturated carboxylic acid metal salt) is 10 to 80 parts by weight with respect to 100 parts by weight of the rubber component. If it is less than 10 parts by weight, a sufficient crosslinking density cannot be obtained. On the other hand, when the content of the α, β-unsaturated carboxylic acid metal salt exceeds 80 parts by weight, it becomes too hard and the strength is lowered. From such a viewpoint, the lower limit of the content of the α, β-unsaturated carboxylic acid metal salt is preferably 12 parts by weight or more, and the upper limit is preferably 50 parts by weight or less, and more preferably 35 parts by weight or less.

  Examples of the peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1- Examples include di-t-butylperoxy-3,3,5-trimethylcyclohexane, n-butyl-4,4-di-t-butylperoxyvalerate, and these may be used alone. You may use combining more than a seed. Of these, dicumyl peroxide is preferable.

  The content of the peroxide is preferably 0.1 to 6.0 parts by weight with respect to 100 parts by weight of the rubber component. When the amount is less than 0.1 part by weight, sufficient hardness tends not to be obtained. On the other hand, if the peroxide content exceeds 6 parts by weight, the crosslinking density becomes excessive and the strength tends to decrease. From such a viewpoint, the lower limit of the peroxide is more preferably 0.2 parts by weight or more, and the upper limit is more preferably 2 parts by weight or less.

  The rubber composition (A) may contain a reinforcing filler. Examples of the reinforcing filler include carbon black, silica, calcium carbonate, clay, talc, alumina, and aluminum hydroxide, and carbon black is particularly preferable. When the reinforcing filler is contained, the content of the reinforcing filler is 90 parts by weight or less, more preferably 50 parts by weight or less with respect to 100 parts by weight of the rubber component. If the content of the reinforcing filler exceeds 90 parts by weight, there is a possibility that excellent low heat buildup property cannot be obtained.

  The rubber composition (A) includes the rubber component, the co-crosslinking agent (α, β-unsaturated carboxylic acid metal salt), the peroxide, and the reinforcing filler, as long as the effects of the present invention are not impaired. Thus, it may contain a compounding agent usually used in the tire industry, for example, zinc oxide, wax, stearic acid, oil, anti-aging agent, vulcanization accelerator and the like. The rubber composition (A) contains a co-crosslinking agent (α, β-unsaturated carboxylic acid metal salt), and therefore preferably does not contain a vulcanizing agent such as sulfur or a sulfur compound.

In this rubber composition (A), butadiene rubber (BR) and an α, β-unsaturated carboxylic acid metal salt are co-crosslinked with a peroxide as an initiator to achieve high elasticity and low heat build-up. . In particular, the ratio (E * 30 / tan δ30) between the complex elastic modulus E * 30 (unit: MPa) and the loss tangent tan δ30 at 30 ° C. can be 700 or more, and this ratio (E * 30 / tan δ30). By using the rubber composition (A) having a weight of 700 or more, it is possible to reduce the rolling resistance while ensuring the steering stability performance at a higher level. At this time, the complex elastic modulus E * 30 is more preferably 75 MPa or more. The upper limit of the ratio E * 30 / tan δ30 is not particularly limited, but is preferably 4000 or less from the viewpoint of cost and workability.

  The rubber composition (A) tends to be inferior to a normal pneumatic tire rubber member in terms of stretchability and tensile strength. However, when the reinforcing rubber layer 7 made of the rubber composition (A) has a sandwich structure disposed between the outer reinforcing cord layer 5 and the inner reinforcing cord layer 6, the reinforcing rubber layer 7 is pulled and compressed. Therefore, the problems of stretchability and tensile strength are solved. That is, by using the sandwich structure, the advantages of the rubber composition (A) can be exhibited while overcoming the drawbacks of the rubber composition (A).

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

An airless tire (tire corresponding to a tire size 145 / 70R12) having the basic structure shown in FIGS. 1 and 2 was prototyped and tested for steering stability and rolling resistance. In Example 5, the outer reinforcing cord layer and the inner reinforcing cord layer are adjacent to each other, and the reinforcing rubber layer is disposed on the radially inner side of the inner reinforcing cord layer. In Comparative Examples 1 to 5 and Examples 1 to 4, a reinforcing rubber layer is disposed between the outer reinforcing cord layer and the inner reinforcing cord layer. Each tire had substantially the same specifications except for the tread ring, and the spoke was integrally formed with the tread ring and the hub by a casting method using urethane resin (thermosetting resin). The outer reinforcing cord layer and the inner reinforcing cord layer are as follows, and each tire has the same specifications.
<Outer reinforcement cord layer>
・ Ply number: 2 ・ Reinforcement cord: Steel cord ・ Cord angle: +21 degrees / -21 degrees <Inner reinforcement cord layer>
-Number of plies: 1-Reinforcement cord: Steel cord-Cord angle: 0 degree (spiral winding)

In Comparative Example 5, the rubber was too hard because the content of α, β-unsaturated carboxylic acid metal salt (zinc methacrylate) was too high, and the tread ring could not be vulcanized. Therefore, the complex elastic modulus E * ₃₀ , loss tangent tan δ ₃₀ , steering stability, and rolling resistance are not measured.

(1) Steering stability:
A sample tire is mounted on four wheels of a vehicle (compact EV: trade name COMS), and a one-seater ride runs on a tire test course on a dry asphalt road surface. displayed. A larger value is better.

(2) Rolling resistance:
The rolling resistance count (rolling resistance / load × 10 ⁴ ) measured under the conditions of a speed of 40 km / h and a load of 1 kN using a rolling resistance tester was displayed as an index with the conventional example 1 as 100. Smaller numbers are better.

The rubber composition materials in Table 1 are as follows.
・ Natural rubber (NR): RSS # 3
-Butadiene rubber (BR): BR150B manufactured by Ube Industries, Ltd.
Carbon black: Diamond Black E (FEF) manufactured by Mitsubishi Chemical Corporation
Zinc methacrylate (α, β-unsaturated carboxylic acid metal salt): Sunester SK-30 manufactured by Sanshin Chemical Industry Co., Ltd.
・ Peroxide: Park Mill D (dicumyl peroxide) manufactured by Nippon Oil & Fats Co., Ltd.
・ Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Sulfur: Powder sulfur manufactured by Karuizawa Sulfur Co., Ltd. ・ Vulcanization accelerator: Noxeller NS (N-tert-butyl-2-benzothiazylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

  As shown in the table, it can be confirmed that the tires of the examples can reduce rolling resistance while ensuring excellent steering stability performance.

1 Airless Tire 2 Tread Ring 3 Hub 4 Spoke 5 Outer Reinforcement Cord Layer 6 Inner Reinforcement Cord Layer 7 Reinforcement Rubber Layer 21 Grounding Surface 22 Tread Rubber Layer 51 First Cord Ply 52 Second Cord Ply 56 First Reinforcement Cord 57 Second Reinforcing cord 61 Third cord ply 66 Third reinforcing cord

Claims (4)

An airless tire comprising a cylindrical tread ring having a ground contact surface, a hub that is arranged radially inside the tread ring and fixed to an axle, and a spoke that connects the tread ring and the hub. ,
The tread ring includes a tread rubber layer that constitutes a ground contact surface, and a reinforcing rubber layer that is disposed inside the tire radius of the tread rubber layer.
The reinforcing rubber layer contains 10 to 80 parts by weight of an α, β-unsaturated carboxylic acid metal salt with respect to 100 parts by weight of a rubber component having a butadiene rubber content of 10 to 100% by weight, and is peroxidized. A rubber composition containing a product,
The rubber composition does not contain carbon black and zinc oxide,
The rubber composition has a complex elastic modulus E * 30 at 30 ° C. measured by a viscoelastic spectrometer of 75 MPa or more.   The tread ring includes an outer reinforcing cord layer provided closest to the tread rubber layer, and an inner reinforcing cord layer provided on the inner side in the tire radial direction of the outer reinforcing cord layer. The airless tire according to claim 1, wherein the reinforcing rubber layer is disposed between the inner reinforcing cord layer and the inner reinforcing cord layer. The reinforcing rubber layer, the ratio of the loss tangent Tanderuta30 at 30 ° C., measured as the complex modulus E * 3 0 in the viscoelastic spectrometer (E * 30 / tanδ30) is characterized in that 700 or more The airless tire according to claim 1 or 2.
The outer reinforcement cord layer includes a first cord ply having a first reinforcement cord that is inclined with respect to the tire circumferential direction;
A second cord ply having a second reinforcing cord provided on the outer side in the tire radial direction of the first cord ply and inclined and arranged at the same angle and in the opposite direction to the first reinforcing cord with respect to the tire circumferential direction; Including
The airless tire according to claim 2, wherein the inner reinforcement cord layer includes a third cord ply having a third reinforcement cord arranged in parallel with the tire circumferential direction or the tire axial direction.

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