JP2010221914A - Run-flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a run-flat tire considerably improving not only the running life during a run-flat running, but also normal rolling resistance and offset wear resistance during a pneumatic tire not being a flat-tire. <P>SOLUTION: In the run-flat tire, a carcass 2 extended toroidaly between a pair of left and right bead sections 30 serves as skeleton; at least two crossing belt layers 6a and 6b, and a tread rubber 1 are sequentially disposed outside in a radial direction of a crown area of the carcass 2; and a reinforcing rubber 5 whose cross-sectional shape in a width direction of the tire is a crescent shape is disposed along the inside portion of a sidewall section 20 of the carcass 2. A loss tangent tanδ of the tread rubber 1 at 60°C satisfies the following expression: 0.05≤tanδ≤0.24. A dynamic storage elastic modulus E'(MPa) of the reinforcing rubber 3 at 30°C satisfies the relationship expressed by the following expression: 5.0≤E'≤12.0. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a run-flat tire (hereinafter, also simply referred to as “tire”), and more specifically increases not only the running life during run-flat running but also normal rolling resistance and uneven wear performance during non-punctured air entry. The present invention relates to a run flat tire that can be improved.

  Compared to the inner surface of the carcass on the side wall of the tire as a run-flat tire that can safely travel a certain distance without losing the load bearing capacity even when the internal pressure of the tire decreases due to puncture etc. The side-reinforcement rubber layer with a crescent-shaped cross section in the tire width direction with high dynamic modulus is arranged to improve the rigidity of the sidewall part so that it can bear the load without extremely increasing the deformation of the sidewall part when the internal pressure is reduced Various types of side reinforcing type run flat tires have been proposed (see, for example, Patent Documents 1 and 2).

  On the other hand, in recent years, in order to improve vehicle safety, it is required to increase the coefficient of friction (μ) on both the dry road surface and the wet road surface of the tire to simultaneously improve the dry performance and wet performance of the tire. Various techniques have been developed to meet the demand for improvement in dry performance and wet performance. For example, in the development of a tire tread rubber composition that directly contributes to the dry performance and wet performance of a tire, the loss tangent (tan δ) near 0 ° C. and the loss tangent (tan δ) near 30 ° C. are used as indices. It is generally effective, and specifically, by using a rubber composition having a high tan δ at around 0 ° C. for the tread, the coefficient of friction (μ) on the wet road surface of the tire is increased to improve the wet performance. On the other hand, by using a rubber composition having a high tan δ at around 30 ° C. for the tread, the friction coefficient (μ) on the dry road surface of the tire can be increased and the dry performance can be improved. .

  In addition, demands for reducing fuel consumption of automobiles are increasing in connection with the movement of global carbon dioxide emission regulations accompanying the recent increase in interest in environmental problems. In order to meet such demands, reduction of rolling resistance is also demanded for tire performance. Here, in developing a rubber composition for a tire tread that contributes to the rolling resistance of the tire, it is generally effective to use a loss tangent (tan δ) around 60 ° C. as an index. By using a rubber composition having a low tan δ in the vicinity for the tread, heat generation of the tire is suppressed and rolling resistance is reduced, and as a result, low fuel consumption of the tire can be improved.

As a technique for realizing a tire having these dry performance, wet performance and low fuel consumption, for example, Patent Document 3 discloses that a rubber component (A) containing 100 parts by mass of a styrene / butadiene copolymer rubber is used. 20 to 70 parts by mass of at least one filler (B) selected from the group consisting of carbon black and white filler, 0 to 30 parts by mass of the softener (C), and a polystyrene equivalent weight average molecular weight of 2 × 10 ^A rubber composition obtained by blending 3 to 30 parts by mass of a (meth) acrylate-based (co) polymer (D) that is ³ to 50 × 10 ³ is disclosed.

Patent Document 4 discloses a dynamic storage elastic modulus E ′ from 30 ° C. to 50 ° C. of the reinforcing rubber of the sidewall portion in order to keep the ride comfort at the time of non-puncture in the side reinforcing type run flat tire. The slope α of the decrease rate (%) of
α ≦ −3.0 × 10 ⁻² [%] / [deg]
And the slope β of the decrease rate (%) of the dynamic storage elastic modulus E ′ from 50 ° C. to 80 ° C. is expressed by the following equation:
β ≧ −8.0 × 10 ⁻² [%] / [deg]
The run flat tire represented by these is also disclosed.

JP 2000-264012 A (Claims etc.) JP 2005-297876 A (Claims etc.) JP 2006-274049 A (Claims etc.) JP 2007-326417 A (Claims etc.)

  With the side-reinforced run-flat tires that have been proposed so far, in order for the tire to run safely over a certain distance without losing its load-bearing capacity when the internal pressure of the tire is reduced due to punctures, etc. became. However, sufficient study has not been made on the running performance during non-punctured air entry. That is, in the run-flat tire, the current situation is that sufficient studies have not been made on the rolling resistance and uneven wear performance at the time of the above-described non-puncture, which are recently required characteristics.

  Therefore, the object of the present invention is to greatly improve not only the running life during run flat running but also the normal rolling resistance and uneven wear performance during non-punctured air entry in a side-reinforced run flat tire. It is to provide a run-flat tire that can be used.

  As a result of intensive studies to solve the above problems, the present inventor has solved the above problems by setting the rubber physical properties of the rubber composition of the tread rubber and the rubber composition of the reinforcing rubber of the sidewall portion within a predetermined range. It has been found that this can be done, and the present invention has been solved.

That is, the run-flat tire of the present invention has a carcass extending in a toroidal shape between a pair of left and right bead portions, and at least two cross belt layers and a tread rubber are sequentially arranged on the outer side in the radial direction of the crown portion of the carcass. And in the run flat tire formed by arranging a reinforcing rubber having a crescent-shaped cross section in the tire width direction on the inner side portion of the sidewall portion of the carcass,
The loss tangent tan δ at 60 ° C. of the tread rubber is the following formula:
0.05 ≦ tan δ ≦ 0.24
Satisfying the formula represented by
The dynamic storage elastic modulus E ′ (MPa) at 30 ° C. of the reinforcing rubber is represented by the following formula:
5.0 ≦ E ′ ≦ 12.0
It is characterized by satisfying the relationship represented by

In the present invention, the tread rubber is composed of 20 to 150 parts by mass of silica with respect to 100 parts by mass of a rubber component composed of natural rubber and / or synthetic diene rubber, and the following general formula:
_{^{R 1 x R 2 y R 3}} z Si-R 4 -S-CO-R 5 (I)
(In the formula, ^{R 1} is ^{R 6 O-, R 6 C (} = O) O-, R 6 R 7 C = NO-, R 6 R 7 CNO-, R 6 R 7 N -, - (OSiR 6 R ⁷ ) _m (OSiR ⁵ R ⁶ R ⁷ ), wherein R ⁶ and R ⁷ are each independently a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group or an aryl group; ² is the same as R ¹ , or a hydrogen atom, or a linear, cyclic or branched alkyl group, alkenyl group or aryl group having 1 to 18 carbon atoms, and R ³ is the same as R ¹ or R ² The same or-[O (R ⁸ O) _m ] _0.5 group, R ⁸ is a linear, cyclic or branched alkylene group having 1 to 18 carbon atoms, m is an integer of 1 to 4, X 1, y 2 and z in R ¹ , R ² and R ³ are
x + y + 2z = 3 and 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1
R ⁴ is a divalent linear, cyclic or branched alkylene group having 1 to 18 carbon atoms, cycloalkylene group, cycloalkylalkylene group, alkenylene group, arylene group or aralkylene group. , R ⁵ is a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aryl group or an aralkyl group) and 1 to 30 parts by mass of a silane compound. It preferably consists of a composition.

  In the present invention, the rubber composition has an aromatic vinyl compound-diene compound copolymer having a weight average molecular weight of 5,000 to 400,000 (polystyrene conversion by gel permeation chromatography) with respect to 100 parts by mass of the rubber component. 2 to 70 parts by mass, the copolymer is preferably composed of 5 to 80% by mass of an aromatic vinyl compound, and the vinyl bond content of the diene compound part is preferably 10 to 80% by mass, The rubber composition preferably contains 5 to 80 parts by mass of the aromatic vinyl compound-diene compound copolymer and the softening agent in a total amount with respect to 100 parts by mass of the rubber component. It is preferable that the ratio of the said silica is 30-100 mass% among dosage amount.

Hereinafter, specific actions of the run flat tire will be described.
The run-flat performance is evaluated by the length of the distance that can be safely traveled in an air-extracted state such as puncture. In a side reinforcing type run-flat tire, a reinforcing rubber having a crescent-shaped cross section in the tire width direction is disposed on an inner surface with a sidewall portion as a center. In the absence of such reinforced rubber, although the tire can maintain the load bearing capacity by the air pressure, the sidewall portion has a relatively low rubber thickness and hardness, so the load supporting capability of the sidewall portion itself is reduced. Are limited, and it is difficult to exhibit run-flat performance during puncture. For this reason, the side wall part and the tread shoulder part and bead part located on both sides of the side wall part are reinforced by the reinforcing rubber, and the load supporting ability in these parts is enhanced, and thereby the side wall part is greatly deformed when air is punctured. In order to maintain the run-flat performance.

  FIG. 2 is a schematic cross-sectional view of the right half of the run flat tire that is running during puncture, and FIG. 3 is a schematic cross-sectional view of the right half of the run flat tire that is running during non-puncture. Such deformation can be confirmed by an investigation using a CT scanner, and it can be seen that the reinforcing rubber 5 in the side wall portion requires very large rigidity to support the load. On the other hand, at the time of non-puncture, that is, when inflated, in a normal tire without the reinforcing rubber 3, the side portion is greatly deformed during loading, and the load is absorbed to transmit an extra force to the ground contact surface. Or, although difficult to convey, in the run flat tire having the reinforcing rubber 3 having high rigidity, the side portion hardly deforms.

  As described above, in the run-flat tire, the inner side of the tire shoulder portion is restrained by the road surface, but since the bending deformation due to the load hardly occurs due to the presence of the reinforcing rubber, the load (F) is directly applied to the outer side of the shoulder portion. It will be transmitted (Fig. 3). As a result, the shoulder block is strongly subjected to lateral shear deformation, resulting in an increase in tread distortion and deterioration in rolling resistance. Moreover, uneven wear is promoted by the lateral shear deformation of the shoulder block and the friction of the road surface. The present inventor has clarified the action of such a run-flat tire, on which a low-loss rubber is disposed on the tread rubber, and a rubber having a predetermined physical property is disposed as a side portion reinforcing rubber. Thus, it has been found that the normal rolling resistance and uneven wear performance during non-puncture can be greatly improved.

  According to the present invention, in a side reinforcing type run-flat tire, not only the running life at the time of run-flat running but also the normal rolling resistance and uneven wear performance at the time of non-punctured air can be greatly improved. A flat tire can be provided.

It is a schematic sectional drawing of the right half of the run flat tire which concerns on one embodiment of this invention. It is a schematic sectional drawing of the right half of the run-flat tire in driving | running | working at the time of puncture. It is a schematic sectional drawing of the right half of the run flat tire in driving | running | working at the time of non-puncture.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of the right half of a run flat tire according to an embodiment of the present invention. The run flat tire 100 shown in FIG. 1 has a pair of left and right bead portions 30 and a pair of sidewall portions 20, and a tread portion 10 connected to both sidewall portions 20, and has a toroidal shape between the pair of bead portions 30. A carcass 2 made of one or more carcass plies extending to reinforce each of these parts 10 to 30, and a pair of crescent-shaped reinforcing rubbers 3 arranged in the tire width direction cross section disposed inside the carcass 2 of the sidewall part 20; Is provided.

  Further, in the illustrated tire, the bead filler 5 is disposed on the outer side in the tire radial direction of the ring-shaped bead core 4 embedded in the bead portion 30, and further on the outer side in the tire radial direction of the crown portion of the carcass 2. In addition to the belt 6 composed of the two crossing belt layers 6a and 6b, a belt reinforcing layer 7a is disposed so as to cover the entire belt 6 outside the belt 6 in the radial direction of the tire. A pair of belt reinforcing layers 7b is arranged so as to cover only both ends of the reinforcing layer 7a. Here, the crossing belt layers 6a and 6b are made of rubberized layers of steel cords extending inclined with respect to the tire equatorial plane, and the two crossing belt layers 6a and 6b constitute the crossing belt layers 6a and 6b. The belt 6 is formed by laminating the cords so as to cross each other with the equator plane interposed therebetween. The belt reinforcing layers 7a and 7b are usually made of rubberized layers of cords arranged substantially parallel to the tire circumferential direction.

In the present invention, the loss tangent tan δ at 60 ° C. of the tread rubber 1 is represented by the following formula:
0.05 ≦ tan δ ≦ 0.24
And the dynamic storage elastic modulus E ′ (MPa) at 30 ° C. of the reinforcing rubber 3 is represented by the following formula:
5.0 ≦ E ′ ≦ 12.0
It is important to satisfy the relationship expressed by

  By setting the loss tangent tan δ at 60 ° C. of the tread rubber 1 in the range of 0.05 to 0.24, the rolling resistance at the time of non-puncture can be reduced. If tan δ is less than 0.05, the steering stability / dry braking performance may be significantly reduced. On the other hand, if tan δ exceeds 0.24, the effect of reducing rolling resistance is reduced. In order to obtain the above effect satisfactorily, the loss tangent tan δ at 60 ° C. is preferably 0.10 to 0.22.

  Further, the dynamic storage elastic modulus E ′ of the reinforcing rubber 3 at 30 ° C. needs to be in the range of 5 to 12.0 (MPa). By setting the dynamic storage elastic modulus E ′ of the reinforcing rubber 3 within the above range, the rigidity of the side portion 20 can be reduced, the strain of the tread 10 can be reduced, and uneven wear can be reduced. If the dynamic storage elastic modulus E ′ is less than 5, it becomes difficult to support the tire at the time of puncture, and as a result, the run-flat travel distance is reduced. On the other hand, if it exceeds 12.0, the deformation of the tread portion 10 becomes large. As a result, the effect of reducing the rolling resistance is reduced, the uneven wear performance is deteriorated, and the riding comfort is further deteriorated. In order to obtain the above effect satisfactorily, the dynamic storage elastic modulus E ′ of the reinforcing rubber 3 is preferably in the range of 7 to 10 (MPa).

Further, in the present invention, the tread rubber 1 is composed of 20 to 150 parts by mass of silica with respect to 100 parts by mass of a rubber component made of natural rubber and / or synthetic diene rubber, and the following general formula:
_{^{R 1 x R 2 y R 3}} z Si-R 4 -S-CO-R 5 (I)
(In the formula, ^{R 1} is ^{R 6 O-, R 6 C (} = O) O-, R 6 R 7 C = NO-, R 6 R 7 CNO-, R 6 R 7 N -, - (OSiR 6 R ⁷ ) _m (OSiR ⁵ R ⁶ R ⁷ ), wherein R ⁶ and R ⁷ are each independently a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group or an aryl group; ² is the same as R ¹ , or a hydrogen atom, or a linear, cyclic or branched alkyl group, alkenyl group or aryl group having 1 to 18 carbon atoms, and R ³ is the same as R ¹ or R ² The same or-[O (R ⁸ O) m] _0.5 group, R ⁸ is a linear, cyclic or branched alkylene group having 1 to 18 carbon atoms, m is an integer of 1 to 4, X 1, y 2 and z in R ¹ , R ² and R ³ are
x + y + 2z = 3 and 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1
R ⁴ is a divalent linear, cyclic or branched alkylene group having 1 to 18 carbon atoms, cycloalkylene group, cycloalkylalkylene group, alkenylene group, arylene group or aralkylene group. R ⁵ is a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aryl group or an aralkyl group) and 1 to 30 parts by mass of a silane compound It is preferable to consist of a rubber composition.

  In the present invention, it is preferable to use the silane compound instead of the usual silane coupling agent because it is possible to achieve both high processability and low rolling resistance. However, it is known that such a silane compound suppresses the gelation of the polymer, improves the processability, and improves the dispersion, thereby reducing the loss. However, there is a problem that steering stability is lowered. However, it has been found that the steering stability can be improved by using the belt structure according to the present invention in combination.

  When the blending amount of the silane compound according to the present invention is less than 1 part by mass, the workability improving effect is insufficient. On the other hand, when it exceeds 30 parts by mass, extrudability such as porous is deteriorated. In addition, since this silane compound couples a rubber polymer, it is more preferable to mix | blend the proton donor represented by DPG (N, N'-diphenylguanidine) etc. in the final kneading | mixing process.

  Moreover, rolling resistance can be further reduced by setting the blending amount of silica within the above range. When the compounding amount of silica is less than 20 parts by mass, the effect of improving the steering stability on a wet road surface is not sufficient. On the other hand, when it exceeds 150 parts by mass, the workability is deteriorated, for example, the rubber composition is deteriorated.

  Further, in the present invention, the rubber composition of the tread rubber 1 has an aromatic vinyl compound-diene compound having a weight average molecular weight (in terms of polystyrene by gel permeation chromatography) of 5,000 to 400,000 with respect to 100 parts by mass of the rubber component. It comprises 2 to 70 parts by mass of a copolymer, the copolymer consists of 5 to 80% by mass of an aromatic vinyl compound, and the vinyl bond content of the diene compound part is 10 to 80% by mass. preferable. More preferably, this copolymer is contained 5-40 mass parts. If the amount is less than 2 parts by mass, the effect of further improving the steering stability is not sufficient. On the other hand, if it exceeds 70 parts by mass, the wear resistance is deteriorated, which is not preferable. By blending such an aromatic vinyl compound-diene compound copolymer within the above preferred range, the elastic modulus is improved without impairing hysteresis loss at high temperatures when compared with blending of a softener such as aroma oil. And maintainability of workability are possible.

  Furthermore, in the present invention, the rubber composition of the tread rubber 1 is a total amount of the aromatic vinyl compound-diene compound copolymer and the softening agent with respect to 100 parts by mass of the rubber component, preferably 5 to 80 parts by mass. More preferably, it contains 5 to 60 parts by mass. If the total amount is less than 5 parts by mass, it is difficult to obtain the desired effect of the present invention.

  Furthermore, in the present invention, the silica ratio in the total filler amount of the rubber composition of the tread rubber 1 is preferably 30 to 100% by mass, more preferably 50 to 100% by mass. When this ratio is less than 30% by mass, it becomes difficult to achieve both high braking performance, particularly wet road surface braking performance and low fuel consumption performance.

  Specific examples of the rubber component of the tread rubber 1 include styrene / butadiene copolymer rubber (SBR), natural rubber (NR), styrene / isoprene copolymer rubber (SIR), and polyisoprene rubber (IR). ), Polybutadiene rubber (BR), butyl rubber (IIR), and synthetic rubbers such as an ethylene / propylene copolymer.

  The silica is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. In addition, wet silica is preferable in that it has excellent effects of achieving both wet performance and low rolling resistance. In addition to silica, inorganic fillers such as aluminum hydroxide and calcium carbonate can be used in appropriate combination.

  The tread rubber 1 may contain a softening agent, and the blending amount thereof is in the range of 0 to 30 parts by mass with respect to 100 parts by mass of the rubber component. When the blending amount of the softening agent exceeds 30 parts by mass, the tensile strength and low heat build-up property of the vulcanized rubber tend to deteriorate. As the softener, process oil or the like can be used, and specific examples of the process oil include paraffin oil, naphthenic oil, aroma oil, and the like. Among these, aromatic oils are preferable from the viewpoint of tensile strength and durability, and naphthenic oils and paraffinic oils are preferable from the viewpoint of hysteresis loss and low temperature characteristics.

  For the tread rubber 1, a general rubber crosslinking system can be used, and it is preferable to use a combination of a crosslinking agent and a vulcanization accelerator. As the cross-linking agent, sulfur or the like can be used, and the amount used thereof is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass as the sulfur content with respect to 100 parts by mass of the rubber component. preferable. When the compounding amount of the crosslinking agent is less than 0.1 parts by mass as the sulfur content with respect to 100 parts by mass of the rubber component, the fracture strength, wear resistance and low heat build-up of the vulcanized rubber are lowered, while exceeding 10 parts by mass. And rubber elasticity is lost. The vulcanization accelerator is not particularly limited, but 2-mercaptobenzothiazole (M), dibenzothiazyl disulfide (DM), N-cyclohexyl-2-benzothiazylsulfenamide (CZ). And thiazole vulcanization accelerators such as Nt-butyl-2-benzothiazolylsulfenamide (NS), and guanidine vulcanization accelerators such as diphenylguanidine (DPG). As a usage-amount of a vulcanization accelerator, the range of 0.1-5 mass parts is preferable with respect to 100 mass parts of rubber components, and the range of 0.2-3 mass parts is more preferable. These vulcanization accelerators may be used alone or in combination of two or more.

  In addition to the above, the tread rubber 1 includes additives usually used in the rubber industry such as anti-aging agent, zinc oxide, stearic acid, antioxidant, carbon black, ozone deterioration preventing agent, and the like. It can be appropriately selected and blended within a range not harming. In addition, about the mixing | blending of the rubber composition of the reinforcement rubber 3, it should not be restrict | limited in particular, As long as the dynamic storage elastic modulus E 'in 30 degreeC is settled in the range of the said formula, it can select suitably according to common usage.

  Further, in the present invention, the desired effect can be obtained by satisfying the conditions relating to the tread rubber 1 and the reinforcing rubber 3. It is not limited. For example, as shown in the figure, a bead core is embedded in each of the pair of bead portions of the tire of the present invention, and the carcass is folded around the bead core from the inside of the tire to the outside and locked. A tread portion made of tread rubber is disposed on the outer periphery of the crown portion of the belt layer, and a sidewall portion is disposed on the side portion of the carcass. Furthermore, as a gas filled in the tire, an inert gas such as nitrogen, argon, helium, or the like can be used in addition to normal air or air whose oxygen partial pressure is adjusted.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Examples 1-6, Comparative Examples 1-4, Conventional Examples 1 and 2)
A side-reinforced run-flat tire as shown in FIG. 1 was prepared, which was sequentially provided with two cross belt layers formed by rubber-drawing steel cords and tread rubber in the radial direction of the crown portion of the carcass. Tables 1 and 2 show the blending contents of the tread rubber of each test tire, and Tables 3 and 4 show the blending contents of the reinforcing rubber, respectively. Tables 5 and 6 show the loss tangent tan δ at 60 ° C. of the tread rubber of each test tire and the dynamic storage elastic modulus E ′ at 30 ° C. of the reinforcing rubber. The tire size of each test tire was 225 / 45R17, and the angle of the crossing belt layer was ± 63 ° with respect to the tire width direction. SBR JSR # 1712 and SBR JSR # 1500 in Tables 1 and 2 below are oil-extended, and the rubber component is 100 parts by mass in a total amount of 118.75 parts by mass of SBR JSR # 1712 and SBR JSR # 1500. It is.

  Each of the obtained test tires was evaluated for rolling resistance, uneven wear, run-flat durability, and actual vehicle feeling. The evaluation method is as follows.

<Dynamic storage elastic modulus E ′ and loss tangent tan δ>
Using a viscoelasticity measuring device manufactured by Rheometrics, the dynamic storage elastic modulus E ′ of the reinforcing layer rubber at 30 ° C. and the loss tangent tan δ of the tread rubber at 60 ° C. were measured under conditions of a frequency of 15 Hz and a strain of 5%.

<Rolling resistance test>
A so-called coasting method in which a rotating drum having a steel smooth surface with an outer diameter of 1707.6 mm and a width of 350 mm is used and rotated at a speed of 0 to 180 km under the action of a JIS standard normal pressure of 4.50 kN. Measured by the method. It shows by the index which made Conventional Example 1 100. It shows that it is excellent in rolling resistance, so that a value is small. The obtained results are shown in Tables 5 and 6.

<Uneven wear test>
Each test tire was mounted on an actual vehicle, and after running 20,000 km, the ratio of the wear amount of the tire center portion and the shoulder portion was measured. The state of uniform wear was evaluated as 100. The obtained results are shown in Tables 5 and 6.

<Runflat durability>
Each test tire was mounted on an actual vehicle and traveled at a speed of 80 km / h with an air pressure of 0 kPa, and those with a travel distance of 80 km or more were evaluated as ◯ and those with less than 80 km were evaluated as x. The obtained results are shown in Tables 5 and 6.

<Real car feeling test: Steering stability and ride comfort>
Each test tire was mounted on an actual vehicle, and the driving stability and riding comfort were tested by the driver's feeling running on the dry (dry) and lubricated (wet) circuit. The results were evaluated on a 10-point scale. The higher the value, the better the handling stability and ride comfort. As for the score, when the score is 0.5, the performance is large and the general driver can recognize the performance difference. The obtained results are shown in Tables 5 and 6.

※１：東海カーボン社製 シースト７ＨＭ
※２：日本シリカ工業製 ニップシールＡＱ
※３：デグッサ社製 Ｓｉ７５
※４：次式で表わされるシラン化合物（ＧＥ製シリコーン）

※５：未変性共重合体分子量８万、ミクロ構造Ｓｔ／Ｖｉ＝２５／６５
※６：スズ変性共重合体分子量８万、ミクロ構造Ｓｔ／Ｖｉ＝２５／６５
※７：Ｎ−フェニル−Ｎ’−（１，３−ジメチルブチル）−ｐ−フェニレンジアミン（大内新興化学工業（株）製 ノクラック６Ｃ）
※８：Ｎ−シクロヘキシル−２−ベンゾチアゾリルスルフェンアミド（大内新興化学工業（株）製 ノクセラーＣＺ）
※９：Ｎ，Ｎ’−ジシクロヘキシル−２−ベンゾチアゾリルスルフェンアミド（大内新興化学工業（株）製 ノクセラ−ＤＺ）
※１０：ＪＩＳ Ｋ６３００に準拠し、１３０℃にてムーニー粘度（ＭＬ１＋４／１３０℃）を測定し、その逆数を比較例１対比の指数とした。結果は、数値が大なるほど良好である。

* 1: Seest 7HM manufactured by Tokai Carbon Co., Ltd.
* 2: NIPSEAL AQ made by Nippon Silica Industry
* 3: Si75 manufactured by Degussa
* 4: Silane compound represented by the following formula (GE silicone)

* 5: Unmodified copolymer molecular weight 80,000, microstructure St / Vi = 25/65
* 6: Tin-modified copolymer molecular weight 80,000, microstructure St / Vi = 25/65
* 7: N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine (Nouchi 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 8: N-cyclohexyl-2-benzothiazolylsulfenamide (Noxeller CZ manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.)
* 9: N, N′-dicyclohexyl-2-benzothiazolylsulfenamide (Noxera-DZ manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 10: In accordance with JIS K6300, Mooney viscosity (ML1 + 4/130 ° C) was measured at 130 ° C, and the reciprocal thereof was used as an index for comparison with Comparative Example 1. The result is better as the numerical value is larger.

  As can be seen from Tables 5 and 6, the run flat tire of the present invention is excellent in rolling resistance, uneven wear, run flat durability, steering stability and riding comfort.

DESCRIPTION OF SYMBOLS 1 Tread rubber 2 Carcass 3 (Side) reinforcement rubber 4 Bead core 5 Bead filler 6 Belt 6a, 6b Intersection belt layer 7a, 7b Belt reinforcement layer 10 Tread part 20 Side wall part 30 Bead part 100 Run flat tire

Claims (5)

A carcass extending in a toroidal shape between a pair of left and right bead portions is used as a skeleton, and at least two cross belt layers and a tread rubber are sequentially arranged on the outer side in the radial direction of the crown portion of the carcass, and the cross-sectional shape in the tire width direction is In a run-flat tire in which a crescent-shaped reinforcing rubber is disposed on the inner portion of the side wall portion of the carcass,
The loss tangent tan δ at 60 ° C. of the tread rubber is the following formula:
0.05 ≦ tan δ ≦ 0.24
Satisfying the formula represented by
The dynamic storage elastic modulus E ′ (MPa) at 30 ° C. of the reinforcing rubber is represented by the following formula:
5.0 ≦ E ′ ≦ 12.0
A run-flat tire characterized by satisfying the relationship expressed by: The tread rubber is 20 to 150 parts by mass of silica with respect to 100 parts by mass of a rubber component made of natural rubber and / or synthetic diene rubber, and the following general formula:
_{^{R 1 x R 2 y R 3}} z Si-R 4 -S-CO-R 5 (I)
(In the formula, ^{R 1} is ^{R 6 O-, R 6 C (} = O) O-, R 6 R 7 C = NO-, R 6 R 7 CNO-, R 6 R 7 N -, - (OSiR 6 R ⁷ ) _m (OSiR ⁵ R ⁶ R ⁷ ), wherein R ⁶ and R ⁷ are each independently a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group or an aryl group; ² is the same as R ¹ , or a hydrogen atom, or a linear, cyclic or branched alkyl group, alkenyl group or aryl group having 1 to 18 carbon atoms, and R ³ is the same as R ¹ or R ² The same or-[O (R ⁸ O) _m ] _0.5 group, R ⁸ is a linear, cyclic or branched alkylene group having 1 to 18 carbon atoms, m is an integer of 1 to 4, X 1, y 2 and z in R ¹ , R ² and R ³ are
x + y + 2z = 3 and 0 ≦ x ≦ 3, 0 ≦ y ≦ 2, 0 ≦ z ≦ 1
R ⁴ is a divalent linear, cyclic or branched alkylene group having 1 to 18 carbon atoms, cycloalkylene group, cycloalkylalkylene group, alkenylene group, arylene group or aralkylene group. R ⁵ is a linear, cyclic or branched alkyl group having 1 to 18 carbon atoms, an alkenyl group, an aryl group or an aralkyl group) and 1 to 30 parts by mass of a silane compound. The run-flat tire according to claim 1, comprising a rubber composition.   The rubber composition contains 2-70 parts by mass of an aromatic vinyl compound-diene compound copolymer having a weight average molecular weight of 5000 to 400,000 (polystyrene conversion by gel permeation chromatography) with respect to 100 parts by mass of the rubber component. The run-flat tire according to claim 2, wherein the copolymer is made of an aromatic vinyl compound of 5 to 80% by mass and the vinyl bond content of the diene compound portion is 10 to 80% by mass.   The run-flat tire according to claim 3, wherein the rubber composition comprises 5 to 80 parts by mass of the total amount of the aromatic vinyl compound-diene compound copolymer and the softening agent with respect to 100 parts by mass of the rubber component.   The run flat tire according to any one of claims 2 to 4, wherein a ratio of the silica is 30 to 100% by mass in a total amount of the filler.

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