JP3532036B2 - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the weight of a pneumatic tire as well as improve its durability in run-flat drive. SOLUTION: A crescent-sectioned side-reinforcing layer 10 arranged between a carcass layer 4A and an inner liner layer 7 in a sidewall part 3 for imparting run-flat performance thereto is composed of a thermoplastic elastomer compound obtained by blending a thermoplastic resin or thermoplastic resin component of Young's moduli of 50 to 500MPa and an elastomer component together. The inner liner layer 7 is composed of a thermoplastic elastomer compound obtained by blending a thermoplastic resin or thermoplastic resin component of air-transmission coefficients not more than 25&times;10<-12> cc.cm/cm<2> .sec.cmHg and an elastomer component together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire provided with a side reinforcing layer for imparting runflat performance, while reducing the weight while running in runflat. Relates to a pneumatic tire having improved durability.

[0002]

2. Description of the Related Art Conventionally, for example, a carcass layer of a sidewall portion has been used as a pneumatic tire having a run-flat performance that enables a vehicle to run even after the air in the tire has been deflated due to a flat tire or the like. There is a proposal of a tire in which a side reinforcing layer having a crescent cross-section made of high hardness rubber is provided between the inner and inner liner layers. By arranging the side reinforcing layer having a crescent-shaped cross section made of high hardness rubber in this way, the rigidity of the side wall portion is significantly increased and the side wall portion is less likely to bend even when air is released.

However, in order to obtain the run flat performance by the side reinforcing layer, it is necessary to secure a certain thickness of the side reinforcing layer. Therefore, there has been a problem that the tire weight is significantly increased, which causes so-called unsprung weight to increase the riding comfort and the rolling resistance. Further, when air is released and the internal pressure is greatly reduced, the sidewall is repeatedly bent due to the rotation of the tire and is repeatedly fatigued.
Therefore, the rubber of the thickened side reinforcing layer generates heat, the reinforcing layer itself is broken, or peeling occurs between the side reinforcing layer and the inner liner layer arranged inside thereof, etc. There was a problem with durability during run-flat driving.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the durability of a pneumatic tire provided with a side reinforcing layer for imparting run-flat performance while running the run-flat while reducing the weight. It is to provide a pneumatic tire capable of being manufactured.

[0005]

According to the present invention, which achieves the above object, a side reinforcing layer having a crescent-shaped cross section is provided between a carcass layer of a sidewall portion and an inner liner layer so as to provide run-flat performance. In a pneumatic tire, the side reinforcing layer has a Young's modulus of 50 to 500 MPa.
Of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component, and the inner liner layer has an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec · cmHg. It is characterized by comprising the following thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component.

As described above, the side reinforcing layer that contributes to the run-flat performance is composed of a thermoplastic resin or a thermoplastic elastomer composition, and the Young's modulus is set within the above range, compared to the case where a conventional high hardness rubber is used. Since the modulus has also been significantly increased, the wall thickness of the side reinforcement layer is greatly reduced when the rigidity of the side wall part is secured at the same level as when the side reinforcement layer made of conventional high hardness rubber is arranged, It is possible to make it thinner and lighter.

Further, when air is released and the internal pressure is greatly reduced, the tire is rotated and a large amount of flexure is repeatedly applied to the sidewall portion, which causes repeated fatigue, but the side reinforcing layer is made to have a high modulus and the wall thickness is greatly reduced. As a result, it is possible to significantly reduce the amount of heat generated by the side reinforcing layer while reducing the amount of bending, and thus the side reinforcing layer itself is not easily broken. Further, since the side reinforcing layer and the inner liner layer are made of the same material, peeling does not easily occur between them, and therefore, the durability during run-flat traveling can be improved.

Further, since the inner liner layer is made of a thermoplastic resin or a thermoplastic elastomer composition, the thickness of the inner liner layer can be made smaller than that of a conventional rubber inner liner layer, and therefore the weight of the inner liner layer is also increased. Can be reduced. Therefore, it is possible to further reduce the weight of the pneumatic tire having run-flat performance.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of a pneumatic tire of the present invention, where 1 is a tread portion, 2 is a bead portion, and 3 is a sidewall portion. Left and right sidewall portions 3 are connected to the left and right bead portions 2 and extend outward in the tire radial direction, and a tread portion 1 extending in the tire circumferential direction is provided between the left and right sidewall portions 3. Two carcass layers 4A and 4B are arranged inside the tire. The beat cores 5 each having a square tire meridian cross-section are arranged in the left and right bead portions 2, and the bead fillers 6 each having a triangular tire meridian cross-section are provided on the outer periphery of the beat core 5. There is.

Both ends 4a of the inner carcass layer 4A are wrapped around the bead filler 6 and folded back from the inside of the tire to the outside of the beet core 5. Both ends 4b of the outer carcass layer 4B are wound around the outside of the beat core 5. An inner liner layer 7 which constitutes an air permeation preventive layer is provided on the entire inner surface of the tire inside the inner carcass layer 4A.

On the outer peripheral side of the carcass layer of the tread portion 1, two belt layers 8 in which reinforcing cords are arranged so as to incline with respect to the tire circumferential direction and intersect each other in opposite directions are embedded. A belt cover layer 9 that protects the belt layer 8 is laminated on the outer periphery of the belt layer 8. A side reinforcing layer 10 having a crescent-shaped tire meridian section for providing run-flat performance is provided between the inner carcass layer 4A and the inner liner layer 7 on both sidewall portions 3. There is. This side reinforcing layer 10
Is formed in the sidewall portion 3 in an annular shape extending along the tire circumferential direction.

The outer peripheral end 10a of the side reinforcing layer 10 is arranged so as to overlap the edge 8a of the belt layer 8 in a plan view, and the inner peripheral end 10b is an outer periphery of the bead filler 6 in a side view. It is arranged so as to overlap the end portion 6a. In addition, CL is a tire equatorial plane. According to the present invention, in the pneumatic tire having the above-mentioned configuration, the inner liner layer 7 and the side reinforcing layer 10 are both made of a thermoplastic resin or a thermoplastic elastomer composition in which a thermoplastic resin component and an elastomer component are blended. There is. The Young's modulus of the thermoplastic resin or the thermoplastic elastomer composition used for the side reinforcing layer 10 is 50 to 5
It is set to 00 MPa. On the other hand, the thermoplastic resin or thermoplastic elastomer composition used for the inner liner layer 7 has an air permeability coefficient of 25 × 10 ⁻¹² cc · cm / cm ² · sec.
-It is configured to be less than cmHg.

When the side-reinforcing layer 10 imparting the run-flat performance is composed of a thermoplastic resin or a thermoplastic elastomer composition having a Young's modulus in the above range, and is composed of a conventional high hardness rubber ( Since the modulus of the side reinforcing layer 10 is made significantly larger than the level at which the Young's modulus is not higher than 20 MPa), when the rigidity of the side wall portion 3 is set to the same level as the conventional one, the thickness of the side reinforcing layer 10 is increased. Can be greatly reduced, and the thickness and weight can be reduced.

Further, when air is released and the internal pressure is greatly reduced, a large flexure repeatedly acts on the sidewall portion due to the rotation of the tire. However, by making the side reinforcing layer 10 a high modulus and greatly reducing the wall thickness, The amount of heat generated in the side reinforcing layer 10 can be significantly reduced while reducing the amount of bending. As a result, the side reinforcing layer itself is not easily destroyed, and the side reinforcing layer 10
Since the inner liner layer 7 and the inner liner layer 7 are made of the same material, peeling does not easily occur between them. Therefore, the durability during run-flat traveling can be improved.

Furthermore, by forming the inner liner layer 7 from a thermoplastic resin or a thermoplastic elastomer composition, the inner liner layer 7 itself has a smaller wall thickness than the inner liner layer made of conventional rubber. The weight can also be reduced, thereby further reducing the weight of the pneumatic tire having run-flat performance.

The Young's modulus of the thermoplastic resin or thermoplastic elastomer composition constituting the side reinforcing layer 10 is 5
When it is less than 0 MPa, the wall thickness cannot be significantly reduced, and it becomes difficult to obtain a high improvement effect in terms of weight. On the other hand, when the pressure exceeds 500 MPa, the rigidity of the side reinforcing layer 10 becomes too high, which deteriorates the riding comfort during normal running and makes the side easily broken, which causes a tire failure.

When the air permeability coefficient of the inner liner layer 7 exceeds 25 × 10 ^-12 cc · cm / cm ² · sec · cmHg,
The function as an air permeation preventive layer that holds the internal pressure of the tire is reduced. Preferably, the air permeability coefficient is 5 × 10 ^-12 cc
・ Cm / cm ²・ sec ・ cmHg or less is recommended. The Young's modulus of the thermoplastic resin or thermoplastic elastomer composition used for the inner liner layer 7 is 1 to 500.
Can be MPa. If the Young's modulus is less than 1 MPa, wrinkles and the like are generated during tire molding, and the moldability is deteriorated. On the other hand, if it exceeds 500 MPa, durability problems occur, which is not preferable. Preferably 10
~ 300 MPa is preferable.

The thickness of the inner liner layer 7 formed into a film can be 0.02 to 0.2 mm. When the wall thickness is less than 0.02 mm, it becomes difficult to block air permeation, and when it exceeds 0.2 mm, the effect of reducing the weight of the inner liner layer 7 itself becomes small.
Preferably, the lower limit value is 0.05 mm or more.

Since the side reinforcing layer 10 and the inner liner layer 7 are both made of a thermoplastic resin or a thermoplastic elastomer composition, they are integrally molded by two-color extrusion or one-color extrusion molding depending on Young's modulus. be able to. In the present invention, the thermoplastic resin forming the side reinforcing layer 10 and the inner liner layer 7 is not particularly limited as long as it can satisfy the Young's modulus and the air permeability coefficient described above. Polyamide resin [for example, nylon 6 (N6), nylon 6
6 (N66), Nylon 46 (N46), Nylon 11
(N11), Nylon 12 (N12), Nylon 610
(N610), nylon 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66 /
610 copolymer (N6 / 66/610), nylon MX
D6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer, nylon 66 /
PPS copolymer] and N-alkoxyalkylated products thereof, for example, methoxymethylated product of 6-nylon, 6
-610-nylon methoxymethylated product, 612-nylon methoxymethylated product, polyester resin [eg, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, Polyarylate (PAR), Polybutylene naphthalate (PB)
N), liquid crystal polyesters, aromatic polyesters such as polyoxyalkylenediimide diacid / polybutylene terephthalate copolymers], polynitrile resins [for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymers ( AS),
(Meth) acrylonitrile / styrene copolymer, (meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate resin [eg, polymethylmethacrylate (PMMA), polyethylmethacrylate], polyvinyl resin [eg, Vinyl acetate, poe vinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PDV)
C), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer], cellulose resin [eg, cellulose acetate, cellulose acetate butyrate] , Fluorinated resins [eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PV
F), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETF
E)], imide resin [for example, aromatic polyimide (P
I)] and the like can be preferably used.

Further, the thermoplastic elastomer composition forming the side reinforcing layer 10 and the inner liner layer 7 can be formed by mixing the above-mentioned thermoplastic resin component with an elastomer component, which also has the Young's modulus described above. And blended to satisfy the air permeability coefficient,
The type and mixing ratio of the materials are not particularly limited.

Examples of the elastomer component include diene rubbers and hydrogenated products thereof (for example, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis B).
R), NBR, hydrogenated NBR, hydrogenated SBR], olefin rubber [eg ethylene propylene rubber (EPD
M, EPM), maleic acid modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (AC
M), ionomer], halogen-containing rubber (for example, Br
-IIR, CI-IIR, bromide of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHR, CHC),
Chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid modified chlorinated polyethylene rubber (M-CM)], silicone rubber [for example,
Methyl vinyl silicone rubber, dimethyl silicone rubber, methylphenyl vinyl silicone rubber], sulfur-containing rubber [for example, polysulfide rubber], fluorine rubber [for example, vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber,
Fluorine-containing silicon rubber, fluorine-containing phosphazene rubber], thermoplastic elastomers (for example, styrene-based elastomer, olefin-based elastomer, ester-based elastomer, urethane-based elastomer, polyamide-based elastomer) and the like can be preferably used.

When the compatibility between the specific thermoplastic resin component and the elastomer component is different, they can be compatibilized by using a suitable compatibilizing agent as the third component. By mixing the compatibilizer in the blend system, the interfacial tension between the thermoplastic resin and the elastomer component is lowered, and as a result, the diameter of the rubber particles forming the dispersion layer becomes fine, so the characteristics of both components are It will be expressed more effectively. As such a compatibilizer, generally, a copolymer having a structure of both or one of a thermoplastic resin and an elastomer component, or an epoxy group, a carbonyl group, a halogen group, which can react with a thermoplastic resin or an elastomer component, It may have a structure of a copolymer having an amino group, an oxazoline group, a hydroxyl group and the like. These may be selected depending on the types of the thermoplastic resin and the elastomer component to be mixed, but those commonly used include styrene / ethylene / butylene block copolymer (SEBS) and its maleic acid modified product, EPDM, EPM. , EPDM / styrene or EPDM / acrylonitrile graft copolymers and maleic acid modified products thereof, styrene / maleic acid copolymers, reactive phenoxine and the like.
The amount of the compatibilizer to be added is not particularly limited, but is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polymer component (total of the thermoplastic resin and the elastomer component).

The composition ratio of the specific thermoplastic resin component (A) and the elastomer component (B) when the thermoplastic resin and the elastomer are blended is not particularly limited, and the Young's modulus, the side reinforcing layer and the inner liner layer are not particularly limited. It may be appropriately determined according to the thickness of the. A preferable range for both the side reinforcing layer and the inner liner layer is 10/90 to 90/10, more preferably 15/85 in terms of a weight ratio of (A) / (B).
~ 90/10.

In addition to the above-mentioned essential polymer components, the polymer composition according to the present invention is mixed with other polymers such as the above-mentioned compatibilizer polymer within a range not impairing the required properties of the tire polymer composition of the present invention. can do. The purpose of mixing other polymers is to improve the compatibility of the thermoplastic resin component and the elastomer component, to improve the moldability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the material used for are polyethylene (PE) polypropylene (PP), polystyrene (PS), ABS, SBS, polycarbonate (PC), and the like. In the polymer composition according to the present invention, a filler (calcium carbonate, titanium oxide, alumina, etc.), a reinforcing agent such as carbon black and white carbon, a softening agent, a plasticizer, which is generally added to the polymer composition, Processing aids, pigments, dyes, anti-aging agents and the like can be optionally added as long as the above Young's modulus requirements are not impaired.

Further, the elastomer component may be dynamically vulcanized when mixed with the thermoplastic resin component. The vulcanizing agent, vulcanizing aid, vulcanizing condition (temperature, time), etc. in the case of dynamically vulcanizing may be appropriately determined according to the composition of the elastomer component to be added, and is not particularly limited. . As the vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used. Specific examples of the ionic vulcanizing agent include powdered sulfur, precipitable sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, alkylphenol disulfide, and the like. 4 phr [rubber component (polymer) 1
Parts by weight per 00 parts by weight].

Further, as the organic peroxide type vulcanizing agent,
Benzoyl peroxide, t-butyl hydroperoxide, 2,4-bichlorobenzoyl peroxide,
2,5-Dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethylhexane-2,5-di (peroxylbenzoate), etc. are exemplified, and for example,
About 1 to 20 phr can be used.

Further, as the phenol resin type vulcanizing agent, bromide of alkylphenol resin, tin chloride,
A mixed crosslinking system containing a halogen donor such as chloroprene and an alkylphenol resin can be exemplified.
About 20 phr can be used. In addition, zinc white (about 5 phr), magnesium oxide (about 4 phr)
, Litharge (about 10 to 20 phr), p-quinone dioxime, p-dibenzoylquinone dioxime, tetrachloro-p-benzoquinone, poly-p-dinitrosobenzene (about 2 to 10 phr), methylene dianiline (0. Two
Approximately 10 phr) can be exemplified.

If desired, a vulcanization accelerator may be added. Examples of the vulcanization accelerator include general vulcanization accelerators such as aldehyde / ammonia-based, guanidine-based, thiazole-based, sulfenamide-based, thiuram-based, dithioate-based, and thiourea-based compounds, for example, 0.5 to About 2 phr can be used. Specifically, the aldehyde / ammonia-based vulcanization accelerator is hexamethylenetetramine, the guanidine-based vulcanization accelerator is diphenylguadinine, and the thiazole-based vulcanization accelerator is dibenzothiazyl disulfide ( DM), 2-mercaptobenzothiazole and its Zn salt, cyclohexylamine salt, etc., and sulfenamide vulcanization accelerators include cyclohexylbenzothiazylsulfenamide (CBS) and N-oxydiethylenebenzothiazyl-2-. Sulfenamide, N-t-butyl-2-benzothiazole Sulfenamide, 2- (thymolpolynyldithio) benzothiazole, etc. As thiuram vulcanization accelerators, tetramethylthiuram disulfide (TMTD), tetraethyl Thiuram disulfide, tetrame Le monosulfide (TMTM), dipentamethylenethiuram tetrasulfide and the like, as the dithio acid salt-based vulcanization accelerator,
Zn-dimethyldithiocarbamate, Zn-diethyldithiocarbamate, Zn-di-n-butyldithiocarbamate, Zn-ethylphenyldithiocarbamate, T
e-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate,
Examples of the thiourea-based vulcanization accelerator such as pipecoline pipecolyl dithiocarbamate include ethylenethiourea and diethylthiourea.

As the vulcanization accelerating aid, general auxiliaries for rubber can be used in combination, for example, zinc white (about 5 phr), stearic acid, oleic acid and their Zn salts (2 to 5 phr). 4 phr) etc. can be used. In the method for producing a thermoplastic elastomer composition, a thermoplastic resin component and an elastomer component (unvulcanized product in the case of rubber) are preliminarily used.
By melt-kneading with a shaft kneading extruder or the like to disperse the elastomer component as a dispersed phase (domain) in the thermoplastic resin component forming the continuous phase (matrix phase). When vulcanizing the elastomer component, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer component.
Further, various compounding agents (excluding the vulcanizing agent) to the thermoplastic resin component or the elastomer component may be added during the kneading, but it is preferable to mix them in advance before the kneading.
The kneader used for kneading the thermoplastic resin component and the elastomer component is not particularly limited, a screw extruder,
A kneader, Banbury mixer, twin-screw kneading extruder or the like can be used. Above all, it is preferable to use a twin-screw kneading extruder for the kneading of the thermoplastic resin component and the elastomer component and the dynamic vulcanization of the elastomer component. Further, two or more kinds of kneaders may be used and kneading may be sequentially performed. As the conditions for melt-kneading, the temperature may be equal to or higher than the temperature at which the thermoplastic resin melts. The shear rate during kneading is 1000 to 7500 Sec.
It is preferably ^-1 . Total kneading time is 30 seconds to 1
When the vulcanizing agent is added for 0 minutes, the vulcanization time after addition is preferably 15 seconds to 5 minutes. The polymer composition produced by the above method is then subjected to extrusion molding, and the inner liner layer formed into a film shape and the side reinforcing layer formed into a crescent-shaped cross section are integrally extruded.

The molded product thus obtained has a structure in which the elastomer component (B) is dispersed as a dispersed phase (domain) in the matrix of the thermoplastic resin component (A). By adopting the dispersed structure in such a state, rubber elasticity can be retained and thermoplastic processing can be performed, and sufficient flexibility can be obtained as the side reinforcing layer and the inner liner layer and the effect of the resin layer as the continuous phase. Rigidity can also be imparted, and molding processability equivalent to that of thermoplastic resin can be obtained at the time of molding regardless of the amount of elastomer component. Is possible.

Adhesion between the molded body and the rubber layer facing the molded body is as follows.
Ordinary rubber-based, phenolic resin-based, acrylic copolymer-based, isocyanate-based polymers and cross-linking agents are applied to the molded product with an adhesive, and the heat and pressure during vulcanization molding are used for adhesion, or , Styrene butadiene styrene copolymer (SBS), ethylene ethyl acrylate (EEA), styrene ethylene butylene block copolymer (SEBS) and other adhesive resins are co-extruded or laminated with the molded product to prepare a molded product. There is a method of adhering to the rubber layer during vulcanization. Examples of solvent-based adhesives include phenol resin-based adhesives (Chemlock 220.
Road Company), chlorinated rubber type (Chemlock 205, Chemlock 234B), isocyanate type (Chemlock 402)
Etc. can be illustrated.

The present invention is particularly limited as long as it is a pneumatic tire in which the side reinforcing layer 10 for providing the run flat performance is arranged between the carcass layer 4A of the sidewall portion 3 and the inner liner layer 7. However, it is preferably used for a pneumatic tire having an aspect ratio of 50% or less, which can effectively increase the rigidity of the sidewall portion 3 and make it difficult to bend.

[0033]

EXAMPLES A tire size of 255 / 40R17 is common, and in the configuration of FIG. 1, a tire of the present invention in which the side reinforcing layer and the inner liner layer are both made of a thermoplastic elastomer composition, and a conventional tire in which both are made of a rubber composition are used. A tire and a tire were produced respectively. In the tire of the present invention, nylon 11 (Rilsan BMNO TL, Atchem Co., Ltd.) is used as the thermoplastic resin component and the elastomer component is used as the side reinforcement layer.
Br-IPMS (EXXPRO 89-4, Exxon Co.) was mixed at a ratio of 55/45 with a twin-screw kneader, and after the elastomer component was sufficiently dispersed in the resin component, zinc white and stearic acid were used as vulcanizing agents. Add 0.4 parts by weight, 2 parts by weight, and 1 part by weight of zinc and stearic acid to 100 parts of the elastomer component,
It was prepared by dynamic vulcanization and pelletization. Further, the pellets were formed into a film with a usual thermoplastic resin T-die extruder. The Young's modulus of the thermoplastic elastomer composition is 70 MPa. In addition, the inner liner layer has nylon 11 (Atochem Co., Lilsan BMNO TL) as a thermoplastic resin component and an elastomer component as well.
Br-IPMS (EXXPRO 89-4, Exxon Co.) was similarly prepared at a ratio of 40/60 to form a film. The air permeability coefficient of the thermoplastic elastomer composition is 12 × 10 ⁻¹² cc ·
cm / cm ² · sec · cmHg, Young's modulus is 40 MPa, and the inner liner layer has a wall thickness of 0.13 mm.

In the conventional tire, rubber having a modulus of 2 MPa is used for the side reinforcing layer, and the inner liner layer has an air permeability coefficient of 55 × 10 ⁻¹² cc · cm / cm ² · sec · cm.
Hg butyl rubber was used. The test tires were subjected to an evaluation test of run-flat running durability and side reinforcement layer weight under the following measurement conditions, and the results shown in Table 1 were obtained. Durability Both test tires were mounted on a rim size 17 × 9-JJ, mounted on the right side of the front wheel of a 3000cc vehicle, and after running an oval course for 10km at 60km / h, tire failure (side reinforcement layer failure) was investigated. 10km if there is no failure
The test was completed after traveling 50 km in a driving manner. Side Reinforcement Layer Weight The weight of the side reinforcement layer of each test tire was measured, and the result was evaluated by an index value with Conventional Tire 1 being 100. The smaller the value, the lighter the weight of the side reinforcing layer, that is, the weight of the tire can be reduced.

[0035]

[Table 1] As is clear from Table 1, it is understood that the tire of the present invention can improve the durability during run-flat running while achieving weight reduction.

[0036]

As described above, according to the present invention, in a pneumatic tire in which a side reinforcing layer imparting run-flat performance is arranged, the side reinforcing layer has a Young's modulus of 50 to 500 MPa.
Of a thermoplastic resin or a thermoplastic elastomer composition in which a thermoplastic resin component and an elastomer component are blended, and the inner liner layer has an air permeability coefficient of 25 × 1.
Since consisted ^{0 -12 cc · cm / cm 2} · sec · Thermoplastic cmHg was below the resin or thermoplastic elastomer composition obtained by blending a thermoplastic resin component and the elastomer component,
It is possible to improve the durability during run-flat running while reducing the weight.

[Brief description of drawings]

FIG. 1 is a half section view of a tire meridian showing an example of a pneumatic tire of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 tread part 2 bead part 3 sidewall part 4A, 4B carcass layer 6 bead filler 6a outer peripheral end part 7 inner liner layer 8 belt layer 8a edge part 10 side reinforcing layer 10a outer peripheral end part 10b inner peripheral end part

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-217923 (JP, A) JP-A-5-169909 (JP, A) JP-A-5-185805 (JP, A) JP-A-7- 52605 (JP, A) JP 57-47205 (JP, A) JP 7-40702 (JP, A) JP 7-70372 (JP, A) JP 47-31761 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 1 / 00,5 / 14,17 / 00 C08L 21 / 00,101 / 00

Claims (3)

(57) [Claims] 1. A pneumatic tire in which a side reinforcing layer having a crescent-shaped cross section is provided between a carcass layer of a sidewall portion and an inner liner layer to provide run-flat performance. It is composed of a thermoplastic resin of 50 to 500 MPa or a thermoplastic elastomer composition in which a thermoplastic resin component and an elastomer component are blended, and the inner liner layer has an air permeability coefficient of 25.
A pneumatic tire made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component, the thermoplastic resin having a viscosity of 10 ⁻¹² cc · cm / cm ² · sec · cmHg or less. 2. The pneumatic tire according to claim 1, wherein the Young's modulus of the thermoplastic resin or the thermoplastic elastomer composition forming the inner liner layer is 1 to 500 MPa. 3. The thickness of the inner liner layer is 0.0
The pneumatic tire according to claim 1 or 2, which has a diameter of 2 to 0.2 mm.