JP6467241B2 - Airless tire - Google Patents

Description

  The present invention relates to an airless tire with reduced rolling resistance.

  As an airless tire, there is known a structure in which a cylindrical tread ring having a ground contact surface and a hub fixed to an axle are connected by spokes having a plurality of spoke plates arranged radially ( For example, see Patent Document 1.)

  In such an airless tire, it is advantageous to use a tread rubber material of a normal pneumatic tire for a tread rubber layer having a ground contact surface in the tread ring from the viewpoint of grip property, wear resistance, and the like.

  However, in pneumatic tires, the load is supported by air with a very small hysteresis loss, whereas in airless tires, solid portions with a greater hysteresis loss than air, specifically tread rings and spoke plates, are used. The load is supported. Therefore, if the tread component used for the tread part of a pneumatic tire is used as it is for the tread ring of an airless tire, the rolling resistance of the airless tire deteriorates to about 2.5 times the rolling resistance of the pneumatic tire. Problem arises.

  Therefore, in order to reduce the rolling resistance of the airless tire to the level of the pneumatic tire, a structure different from the tread structure in the pneumatic tire is used, and a member having physical properties different from that of the tread constituent member in the pneumatic tire is used. It is necessary to form a tread ring.

JP, 2014-218132, A

  Accordingly, the present invention employs a sandwich structure in which a shear rubber layer is sandwiched between the first and second reinforcing cord layers in the tread ring, and the tensile elastic modulus in the tire circumferential direction in the first and second reinforcing cord layers While ensuring excellent steering stability performance based on identifying the ratio of the shear modulus of the shear rubber layer, the ratio of the loss tangent tan δ to the shear modulus of the shear rubber layer, and the value of the loss tangent tan δ, respectively. An object of the present invention is to provide an airless tire that can reduce rolling resistance.

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 having a grounding surface, a first reinforcing cord layer provided closest to the tread rubber layer, and a second inner side provided in the radial direction of the first reinforcing cord layer. A reinforcing cord layer and a shear rubber layer provided between the first and second reinforcing cord layers,
The first reinforcing cord layer is formed of two cord plies,
The second reinforcing cord layer is formed from one cord ply,
Moreover, the shear rubber layer is characterized in that a loss tangent tan δ is 0.06 or less and a ratio Ee / tan δ between the loss tangent tan δ and the shear elastic modulus Ee is 1500 (unit MPa) or more.

  In the airless tire according to the present invention, the shear elastic modulus Ee is preferably 20 MPa or more.

  In the airless tire according to the present invention, the shear rubber layer comprises 10 to 100 parts by mass of a rubber component having a butadiene rubber content of 10 to 100% by mass, and 10 to 10% of an α, β-unsaturated carboxylic acid metal salt. The rubber composition preferably contains 80 parts by weight and contains a peroxide.

In the airless tire according to the present invention, the first, the second reinforcing cord layer, with a sulfur vulcanized topping rubber in which the sulfur vulcanizing agents, the shear rubber layer and the first reinforcing cord layer between, and between the shearing rubber layer and the second reinforcing cord layer, that is interposed an insulation layer that prevents the migration from the topping rubber of the sulfur to the shear rubber layer in vulcanization preferable.

  In the airless tire according to the present invention, it is preferable that the insulation layer is formed of an adhesive.

In the airless tire according to the present invention, the tread ring, said first, together with a second said shear rubber layer and a reinforcing cord layer is comprises an overlapping region overlapping the radially inner and outer, axially of the overlap region internal width Wy is the not less than 60% of the tire axial direction of the width Wr of the tread ring, yet the first, both ends of the second reinforcing cord layer, and both ends of the shear rubber layer of the tread-ring It is preferable to terminate with.

In the airless tire according to the present invention, each of the two cord plies of the first reinforcing cord layer includes a cord array in which the reinforcing cords are arranged at an angle of 5 to 35 ° with respect to the tire circumferential direction. And a topping rubber covering the surface thereof.
In the airless tire according to the present invention, it is preferable that the two cord plies of the first reinforcing cord layer are arranged with inclination directions of the reinforcing cords different from each other.
In the airless tire according to the present invention, the one cord ply of the second reinforcing cord layer includes a cord array in which the reinforcing cords are arranged at an angle of less than 5 ° with respect to the tire circumferential direction, and a surface thereof. And a topping rubber covering the surface.

  The shear elastic modulus Ee in the shear rubber layer is a value obtained by multiplying the static tensile elastic modulus measured at a temperature of 30 ° C. and an elongation of 2.00% by 1/3, in accordance with JIS K6251. The test piece may be formed by cutting out from the vulcanized tread ring or by press vulcanizing an unvulcanized shear rubber layer before forming the tread ring at 170 ° C. for 20 minutes.

  The loss tangent tan δ in the shear rubber layer is based on JIS-K6394, and using a viscoelastic spectrometer, initial strain (10%), dynamic strain (± 1%), frequency (10 Hz), deformation mode (tensile), It is the value measured at the measurement temperature (30 ° C.). The test piece may be formed by cutting out from the vulcanized tread ring or by press vulcanizing an unvulcanized shear rubber layer before forming the tread ring at 170 ° C. for 20 minutes.

  In order to reduce the rolling resistance of the airless tire, it is important to use a low heat-generating rubber having a low loss tangent tanδ as the rubber used for the tread ring and to keep the deformation amount of the rubber low.

  Therefore, as described above, the present invention employs a sandwich structure in which the shear rubber layer is sandwiched between the first and second reinforcing cord layers in the tread ring. Therefore, part of the load received during traveling can be supported by the tensile elastic force in the circumferential direction of the first and second reinforcing cord layers, and the deformation amount of the tread ring can be suppressed low.

  At this time, when the tensile elastic modulus Eb of the first and second reinforcing cord layers is too small as compared with the shear elastic modulus Ee of the shear rubber layer, the function by the sandwich structure is not sufficiently exhibited. Therefore, in order to keep the deformation amount of the tread ring low, reduce rolling resistance and improve steering stability, it is important to set the elastic modulus ratio Eb / Ee to 100 or more.

  On the other hand, in order to reduce the rolling resistance, it is also important to suppress the loss tangent tan δ of the shear rubber layer to 0.06 or less. However, in the case of an ordinary sulfur vulcanized rubber composition, when the loss tangent tan δ is lowered, the shear elastic modulus Ee tends to be lowered at the same time. As a result, although the loss tangent tan δ decreases, the amount of deformation of the shear rubber layer increases, and the rolling resistance cannot be sufficiently reduced. Therefore, in order to reduce the rolling resistance, it is also important to regulate the ratio Ee / tanδ between the shear elastic modulus Ee and the loss tangent tanδ in addition to the loss tangent tanδ. In particular, the ratio Ee / tanδ is 1500 (unit MPa). It was found that it is necessary to use the above shear rubber layer.

  Such physical properties can be obtained by, for example, a butadiene-based rubber composition using an α, β-unsaturated carboxylic acid metal salt as a cross-linking agent. It is smaller than the composition, lacks flexibility, and is brittle. Therefore, it has been difficult to use it as a normal tire rubber. However, as in the present invention, when used for a shear rubber layer having a sandwich structure, since the shear rubber layer is covered with a reinforcing cord layer, it is not directly subjected to an impact from the outside and is not locally bent. When this happens, the tread rubber and the reinforcing cord layer relieve it, so that it can be used without any problem.

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 an expanded sectional view of the tread ring of FIG. It is sectional drawing which exaggerates and shows an insulation layer.

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 contact surface 2S, a hub 3 that is arranged on the inner side in the radial direction of 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 corresponds to a tire wheel, and includes a disk-shaped disk portion 31 fixed to the axle and a cylindrical spoke attachment portion 32 formed on the outer periphery of the disk portion 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 includes a plurality of spoke plates 4A that connect the tread ring 2 and the hub 3 in a substantially radial manner. The spoke 4 is integrally formed with the tread ring 2 and the hub 3 by casting with a polymer material. As the polymer material, a thermoplastic resin or a thermosetting resin can be used. From the viewpoint of safety, a thermosetting resin such as an epoxy resin, a phenol resin, a urethane resin, a silicon resin, or a polyimide resin is used. Resins, melamine resins, and the like are suitable. In particular, urethane resins are excellent in elastic characteristics and can be more suitably employed.

  Next, as shown in FIGS. 2 and 3, the tread ring 2 includes a tread rubber layer 22 constituting the ground contact surface 2 </ b> S, a first reinforcing cord layer 5 provided closest to the tread rubber layer 22, and It has the 2nd reinforcement cord layer 6 provided in the tire radial direction inner side of the 1st reinforcement cord layer 5, and the shear rubber layer 7 provided between the 1st, 2nd reinforcement cord layers 5 and 6. FIG. That is, a sandwich structure in which the shear rubber layer 7 is sandwiched between the first and second reinforcing cord layers 5 and 6 is provided.

  Tread grooves (not shown) are formed in various pattern shapes on the ground contact surface 2S, which is the outer peripheral surface of the tread rubber layer 22, in order to provide wet performance. As the tread rubber layer 22, a rubber composition excellent in grip with the road surface and excellent wear resistance is suitably employed as in the pneumatic tire.

In the present example, the first reinforcing cord layer 5 is formed of a total of two cord plies 5A and 5B that are placed inside and outside in the radial direction. Each cord ply 5A, 5B is formed from a cord array in which reinforcing cords are arranged at an angle θ1 (shown in FIG. 2) with respect to the tire circumferential direction, and a topping rubber covering the surface thereof. The reinforcing cord, the cord arrangement density, and the angle θ1 in the first reinforcing cord layer 5 are appropriately set according to the tensile elastic modulus Eb ₁ in the tire circumferential direction of the first reinforcing cord layer 5 described later. In this example, each cord ply 5A, 5B includes a cord arrangement body in which steel cords (reinforcing cords) are arranged at an angle θ1 of 5 to 35, for example. Further, the cord plies 5A and 5B are arranged with the inclination directions of the reinforcing cords different from each other so that the reinforcing cords cross each other between the plies. Thereby, the 1st reinforcement cord layer 5 can raise in-plane rigidity, can raise cornering power generated when a slip angle is attached, and can improve turning performance.

In this example, the second reinforcing cord layer 6 is formed from one cord ply 6A. The cord ply 6A is formed of a cord array in which reinforcing cords are arranged at an angle θ2 (shown in FIG. 2) with respect to the tire circumferential direction, and a topping rubber that covers the surface thereof. Reinforcing cords of the second reinforcing cord layer 6, the coding sequence density, angle θ2 is also set in accordance with the tensile modulus Eb ₂ in the tire circumferential direction of the second reinforcing cord layer 6 to be described later. In this example, the cord ply 6A includes a cord array body in which a steel cord (reinforcing cord) is spirally wound at an angle θ2 of less than 5 °. Thus, the second reinforcing cord layer 6 can increase the tensile elastic modulus Eb ₂ in the tire circumferential direction while the lighter.

  The first and second reinforcing cord layers 5 and 6 are symmetrical with respect to the tire equator line. If there is no line symmetry, the reinforcing cord layers 5 and 6 are twisted when loaded, and the tread ring 22 is deformed into a strain, which makes smooth rolling difficult.

  In this example, the topping rubber used for each cord ply 5A, 5B, 6A is a sulfur vulcanized rubber composition using sulfur as a vulcanizing agent, for example, natural rubber (NR ), Butadiene rubber (BR), diene rubber such as styrene-butadiene rubber (SBR), or a mixture thereof.

  Next, the shear rubber layer 7 is provided between the first and second reinforcing cord layers 5 and 6. Thereby, a part of the load received by the tread ring 2 during traveling can be supported by the tensile elastic force in the tire circumferential direction in the first and second reinforcing cord layers 5 and 6, and the load supporting ability can be effectively increased. The amount of deformation of the tread ring 2 can be suppressed by increasing.

At this time, when the tensile elastic moduli Eb ₁ and Eb _{2 of} the first and second reinforcing cord layers 5 and 6 are too small as compared with the shear elastic modulus Ee of the shear rubber layer 7, the function by the sandwich structure is performed. Will not be fully demonstrated. Therefore, each elastic modulus ratio Eb ₁ / Ee and ratio Eb ₂ / Ee is ensured to be 100 or more, thereby suppressing the deformation amount of the tread ring 2 and reducing rolling resistance and excellent driving stability. doing. In particular, in order to suppress deformation of the tread ring 2, the ratio Eb ₁ / Ee and the ratio Eb ₂ / Ee are preferably 500 or more, and more preferably 1000 or more. The tensile elastic modulus Eb ₁ and Eb ₂ may be different from each other, but if they are different, the reinforcing cord layer having the higher tensile elastic modulus becomes excessive quality, resulting in a weight reduction and cost disadvantage. Therefore, the ratio _Eb 1 / Eb ₂ tensile modulus in the range of 0.8 to 1.2, and particularly preferably equal.

Further, in order to suppress deformation of the tread ring 2, it is necessary that the shear rubber layer 7 has a high shear modulus Ee itself. Therefore, it is preferable to set the shear elastic modulus Ee to 20 MPa or more, and further to 30 MPa or more. Thereby, combined with the values of the ratio Eb ₁ / Ee and the ratio Eb ₂ / Ee described above, the load supporting ability can be further enhanced. As a result, it is possible to further reduce the rolling resistance and steering stability, or to reduce the weight of the tread ring 2 while ensuring the low rolling resistance and steering stability at a certain level.

  On the other hand, in order to reduce rolling resistance, it is also important to form the shear rubber layer 7 with a low heat-generating rubber composition having a small hysteresis loss. As a result of the experiments by the present inventors, it has been found that if the loss tangent tan δ of the shear rubber layer 7 is about 0.06, it is possible to ensure a rolling resistance close to that of a pneumatic tire. Therefore, in the present invention, the loss tangent tan δ is set to 0.06 or less.

  However, in the case of an ordinary sulfur vulcanized rubber composition, if the loss tangent tan δ is lowered, the shear modulus Ee tends to be lowered at the same time. As a result, even if the loss tangent tan δ is reduced, the amount of deformation of the shear rubber layer 7 is increased, and the rolling resistance cannot be reduced sufficiently. Therefore, in order to reduce the rolling resistance, it is also important to regulate the ratio Ee / tanδ between the shear elastic modulus Ee and the loss tangent tanδ in addition to the loss tangent tanδ. In particular, the rolling resistance can be sufficiently reduced by setting the ratio Ee / tan δ to 1500 (unit MPa) or more.

  Here, a rubber composition having a loss tangent tan δ of 0.06 or less and a ratio Ee / tan δ of 1500 (unit MPa) or more is formed by a conventional sulfur vulcanized rubber composition used for pneumatic tires. Difficult to do. The reason is that, in the case of a sulfur vulcanized rubber composition, if the loss tangent tan δ is reduced to 0.06 or less, the shear modulus Ee also decreases, and it becomes difficult to increase the ratio Ee / tan δ to 1000 or more. It is.

  As a result of the present inventors' research in such a situation, it has been found that the above physical properties can be ensured by using, for example, a butadiene-based rubber composition A using a metal salt of α, β-unsaturated carboxylic acid as a crosslinking agent. Obtained. This rubber composition A is characterized in that it has a small elongation and is brittle compared to a normal sulfur vulcanized rubber composition, and thus has not been used for pneumatic tires. However, when used for the sandwich structure rubber rubber layer 7 as in the present invention, the shear rubber layer 7 is covered and protected by the reinforcing cord layers 5 and 6 so that it is not directly subjected to external impact. In addition, even when local bending occurs, the tread rubber layer 4 and the reinforcing cord layers 5 and 6 relieve the problem, so that the durability can be used without any problem.

  Next, the rubber composition A of the shear rubber layer 7 will be described. Table 1 shows a blending example of the rubber composition A.

  This 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. And containing a peroxide. In this rubber composition A, butadiene rubber (BR) and an α, β-unsaturated carboxylic acid metal salt are co-crosslinked using a peroxide as an initiator, thereby making it possible to achieve high elasticity which has been difficult with a rubber material of sulfur vulcanization. And low exothermic property is achieved.

  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.

  In addition to the rubber component, co-crosslinking agent (α, β-unsaturated carboxylic acid metal salt), peroxide, and reinforcing filler, the rubber composition A is within a range that does not impair the effects of the present invention. 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 may be contained.

  In addition, since the rubber composition A contains a co-crosslinking agent (α, β-unsaturated carboxylic acid metal salt), it does not contain a vulcanizing agent such as sulfur or a sulfur compound. However, if the shear rubber layer 7 is adjacent to the first and second reinforcing cord layers 5 and 6, sulfur contained in the topping rubber of the reinforcing cord layers 5 and 6 migrates to the shear rubber layer 7 during vulcanization. As a result, the physical properties of the shear rubber layer 7 may be changed. Therefore, in this example, as exaggeratedly shown in FIG. 4, between the first reinforcing cord layer 5 and the shear rubber layer 7 and between the second reinforcing cord layer 6 and the shear rubber layer 7, It is preferable to interpose an insulation layer 25 that prevents migration of sulfur. Although this insulation layer 25 is not particularly restricted, for example, an adhesive such as Chemlock 6100 to 6254 (trade name, manufactured by Lord Corporation) can exhibit both effects of suppressing sulfur migration and adhesion, and thus is preferably employed. Yes. The thickness of the insulation layer 25 is not particularly restricted, but if it is too thin, it will not adhere, and if it is too thick, the adhesive layer itself is fragile and may break. From such a viewpoint, the thickness is preferably 3 to 100 μm, more preferably 7 to 50 μm.

  As shown in FIG. 3, the tread ring 2 has a function of effectively supporting the load in the overlapping region Y where the first and second reinforcing cord layers 5 and 6 and the shear rubber layer 7 overlap each other in the radial direction. To do. Therefore, in order to suppress deformation of the tread ring 2, the width Wy of the overlapping region Y in the tire axial direction is 60% or more, further 70% or more, and further 80% of the width Wr of the tread ring 2 in the tire axial direction. % Or more is preferable. However, when both ends in the tire axial direction of the first and second reinforcing cord layers 5 and 6 and both ends in the tire axial direction of the shear rubber layer 7 are exposed from the side surfaces of the tread ring 2, peeling from the exposed portion as a starting point, etc. May cause damage. Therefore, it is preferable that both ends of the first and second reinforcing cord layers 5 and 6 and both ends of the shear rubber layer 7 are terminated inside the tread ring 2.

  In order to reduce the weight, it is more preferable that the widths in the tire axial direction of the first and second reinforcing cord layers 5 and 6 are equal to each other.

  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 (a tire corresponding to a tire size 145 / 70R12) having the basic structure of FIG. 1 was prototyped and tested for steering stability and rolling resistance. 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 first and second reinforcing cord layers are as follows, and the tensile elastic modulus Eb1 in the tire circumferential direction is changed by changing the thickness of the reinforcing cord, the number of cords to be driven, and the cord angle.
<First reinforcing cord layer>
・ Number of plies: 2 ・ Reinforcement cord: Steel cord ・ Cord angle: +21 degrees / -21 degrees <second reinforcement cord layer>
-Number of plies: 1-Reinforcement cord: Steel cord-Cord angle: 0 degree (spiral winding)
<Shear rubber layer>
Thickness: 4mm
<Insulation layer>
・ Adhesive: Chemlock 6125 (manufactured by Lord)

  Further, in the shear rubber layer of Comparative Example 2, a sulfur vulcanized rubber composition B using a diene rubber was used, and the shear elastic modulus Ee and the loss tangent tan δ were changed by adjusting the carbon black and sulfur contents. ing. Moreover, the rubber composition A which used Table 1 as a basic composition is used for the shear rubber layer of Comparative Examples 1 and 3 and Examples 1 to 9, and by adjusting the content of the α, β-unsaturated carboxylic acid metal salt Further, the shear elastic modulus Ee and the loss tangent tan δ are changed.

(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 using a rolling resistance tester under conditions of a speed of 40 km / h and a weight of 1.17 kN was displayed as an index with the conventional example 1 as 100. Smaller numbers are better.

  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.

DESCRIPTION OF SYMBOLS 1 Airless tire 2 Tread ring 2S Grounding surface 3 Hub 4 Spoke 5 First reinforcement cord layer 6 Second reinforcement cord layer 7 Shear rubber layer 22 Tread rubber layer 25 Insulation layer Y Overlapping region

Claims (9)

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 having a grounding surface, a first reinforcing cord layer provided closest to the tread rubber layer, and a second inner side provided in the radial direction of the first reinforcing cord layer. A reinforcing cord layer and a shear rubber layer provided between the first and second reinforcing cord layers,
The first reinforcing cord layer is formed of two cord plies,
The second reinforcing cord layer is formed from one cord ply,
In addition, the shear rubber layer has a loss tangent tan δ of 0.06 or less, and a ratio Ee / tan δ of the loss tangent tan δ to the shear elastic modulus Ee is 1500 (unit MPa) or more. The airless tire according to claim 1, wherein the shear elastic modulus Ee is 20 MPa or more .   The shear 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. The airless tire according to claim 1 or 2, comprising a rubber composition containing a product. The first, the second reinforcing cord layer, with a sulfur vulcanized topping rubber in which the sulfur vulcanizing agents, between the shear rubber layer and the first reinforcing cord layer, and the second between the shear rubber layer and a reinforcing cord layer, airless according to claim 3, characterized in that is interposed insulation layer that prevents the migration from the topping rubber of the sulfur to the shear rubber layer in vulcanization tire.   The airless tire according to claim 4, wherein the insulation layer is formed of an adhesive. The tread ring, said first, together with a second said shear rubber layer and a reinforcing cord layer is comprises an overlapping region overlapping the radially inner and outer, axially of the width Wy of the overlap region, the tread ring not less than 60% of the tire axial direction of the width Wr, moreover the first, wherein both ends of the second reinforcing cord layer, and both ends of the shear rubber layer, characterized in that terminating in the interior of the tread-ring Item 6. The airless tire according to any one of Items 1 to 5. Each of the two cord plies of the first reinforcing cord layer includes a cord array in which the reinforcing cords are arranged at an angle of 5 to 35 ° with respect to the tire circumferential direction, and a topping rubber that covers the surface thereof. The airless tire according to any one of claims 1 to 6, wherein the tire is formed from. The airless tire according to claim 7, wherein the two cord plies of the first reinforcing cord layer are arranged with the reinforcing cords inclined in different directions. The one cord ply of the second reinforcing cord layer is formed of a cord array in which reinforcing cords are arranged at an angle of less than 5 ° with respect to the tire circumferential direction, and a topping rubber covering the surface thereof. The airless tire according to any one of claims 1 to 8, wherein:

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