JP2020006822A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire improving a steering stability by addition of a film layer and enabling prevention of film layer peeling during travel.SOLUTION: In a pneumatic tire comprising: an annular tread 1 extending in a tire circumferential direction; a pair of side walls 2 disposed at both sides of the tread 1; and a pair of beads 3 disposed inside the side walls 2 in a tire radial direction, a film layer 11 comprising a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in the thermoplastic resin is arranged on a tire inner surface and besides, plural through-holes 13 are formed along a tire circumferential direction in at least a part of an area of the film layer 11 in the tire radial direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire having a film layer made of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin on the inner surface of the tire. The present invention relates to a pneumatic tire capable of preventing the peeling of a film layer during running while improving the pneumatic tire.

  In a pneumatic tire, it is common to arrange an air permeation prevention layer made of butyl rubber inside a carcass layer, but in recent years, a thermoplastic resin or a thermoplastic resin in which an elastomer is blended in a thermoplastic resin inside a carcass layer. It has been proposed to arrange an air permeation preventing layer made of a film of a plastic elastomer composition (for example, see Patent Documents 1 to 3). Such an air permeation preventing layer made of a film of a thermoplastic resin material greatly contributes to weight reduction of the tire.

  By the way, since pneumatic tires for motor sports do not require long-term air holding capability, the air permeation prevention layer made of butyl rubber has been removed for the purpose of weight reduction. There is a disadvantage that the bladder sometimes slips against the inner surface of the tire, and the carcass line is not formed as designed. Therefore, in a pneumatic tire for motor sports, by arranging a film layer of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin on the inner surface of the tire, while achieving weight reduction, Attempts have been made to improve the sliding of the bladder against the inner surface of the tire during vulcanization. Further, since the film layer contributes to an increase in tire rigidity, an effect of improving steering stability is expected.

  However, especially in pneumatic tires for motor sports, the tire itself becomes hot during running, so if there is residual air between the film layer and the carcass layer, the air reservoir expands and during running, There is a disadvantage that the film layer is peeled off from the inner surface of the tire.

JP 2007-30636 A JP 2007-50614 A JP 2007-99146 A

  An object of the present invention is to provide a pneumatic tire capable of improving steering stability by adding a film layer and preventing peeling of the film layer during running.

  In order to achieve the above object, a pneumatic tire of the present invention includes a ring-shaped tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and these sidewall portions. In a pneumatic tire having a pair of bead portions arranged radially inward of the tire, a film layer made of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin is disposed on the tire inner surface. A plurality of through holes are formed along at least a part of the film layer in the tire radial direction along the tire circumferential direction.

  In the present invention, since a film layer made of a thermoplastic resin or a thermoplastic elastomer composition is disposed on the tire inner surface, the bladder slides smoothly against the tire inner surface during tire vulcanization, and the addition of the film layer Steering stability can be improved by increasing tire stiffness. Moreover, since a plurality of through holes are formed along the tire circumferential direction in at least a part of the film layer in the tire radial direction, air remaining between the film layer and the carcass layer penetrates during tire molding. It is discharged to the tire cavity through the hole. Therefore, when the tire itself becomes hot during traveling, it is possible to prevent the air reservoir from expanding between the film layer and the carcass layer, and to effectively prevent peeling of the film layer during traveling. . Further, the film layer does not function as an air permeation preventing layer, but is provided for the purpose of improving the bladder slip during tire vulcanization and obtaining a reinforcing effect. There is no problem even if the through holes are formed.

  In the present invention, the maximum dimension of each of the through holes is preferably 0.1 mm to 1.0 mm. By setting the maximum dimension of each of the through holes in the above range, it is possible to sufficiently secure the tire rigidity while effectively preventing the film layer from peeling off.

The number of through holes per 100 cm ² in at least a part of the region where the through holes are formed is preferably 1 to 400. By setting the number of through holes per 100 cm ² within the above range, it is possible to sufficiently secure the tire rigidity while effectively preventing peeling of the film layer.

BRIEF DESCRIPTION OF THE DRAWINGS It is a meridian sectional view which shows the pneumatic tire for motor sports which consists of embodiment of this invention. FIG. 2 is a side view showing the inner surface of the pneumatic tire of FIG. 1. It is sectional drawing which expands and shows the A section of FIG. FIG. 3 is an enlarged plan view showing a portion B in FIG. 2.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire for motor sports according to an embodiment of the present invention, and FIGS. 2 to 4 show essential parts thereof.

  As shown in FIG. 1, the pneumatic tire according to the present embodiment includes a tread portion 1 extending in the tire circumferential direction and having an annular shape, and a pair of sidewall portions 2 and 2 disposed on both sides of the tread portion 1. And a pair of beads 3, 3 arranged radially inward of the sidewalls 2 in the tire radial direction.

  A carcass layer 4 is mounted between the pair of bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside of the tire to the outside around a bead core 5 arranged in each bead portion 3. In the carcass layer 4, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 75 ° to 90 °. As a reinforcing cord of the carcass layer 4, an organic fiber cord made of rayon, polyester, aromatic polyamide or the like is preferably used. The carcass layer 4 has a main body part 4a and a winding part 4b bordering the bead core 5.

  In each bead portion 3, a bead filler 6 made of a rubber composition having a triangular cross section is disposed on the outer periphery of the bead core 5, and the bead filler 6 is sandwiched between the main body portion 4a and the winding portion 4b of the carcass layer 4. I have. An organic fiber reinforcing layer 7 containing an organic fiber cord inclined with respect to the tire circumferential direction is embedded in the bead portion 3 so as to surround the bead core 5 and the bead filler 6.

  On the other hand, a plurality of belt layers 8 are buried on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 8 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to cross each other between the layers. In the belt layer 8, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. As a reinforcing cord of the belt layer 8, a steel cord is preferably used. At least one belt cover layer 9 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 8 for the purpose of improving high-speed durability. I have. As a reinforcing cord for the belt cover layer 9, an organic fiber cord such as nylon or aramid is preferably used.

  The above-described tire internal structure is a typical example of a pneumatic tire, but is not limited thereto.

  In the pneumatic tire, a reinforcing film layer 11 made of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin is provided inside the carcass layer 4. An inner liner layer 10 (see FIG. 3), which is formed by laminating a tie rubber layer 12 for bonding to the inner rubber 4, is disposed.

  As shown in FIGS. 2 to 4, a plurality of through holes 13 are formed in at least a part of the film layer 11 in the tire radial direction along the tire circumferential direction. Here, the tire radial direction means the tire meridian direction. The through hole 13 needs to be formed in at least a part of the film layer 11 in the tire radial direction, but is preferably formed in at least the shoulder region S of the film layer 11, More preferably, it is formed. Since the shoulder region S is a region where the bladder finally comes into contact with the tire inner surface during vulcanization, air tends to remain. Therefore, by arranging the through holes 13 at least in the shoulder region S of the film layer 11, the effect of preventing the film layer 11 from peeling can be effectively exerted. Although the through-hole 13 is depicted as a space in FIG. 3, the tie rubber layer 12 may be filled in the through-hole 13.

  In the above-described pneumatic tire, the reinforcing film layer 11 made of a thermoplastic resin or a thermoplastic elastomer composition is provided on the inner surface of the tire, so that the tire does not significantly increase in mass when tire vulcanizing. In addition to improving the sliding of the bladder with respect to the inner surface of the tire, the addition of the film layer 11 can increase the tire rigidity and improve the steering stability.

  Moreover, since a plurality of through holes 13 are formed in at least a part of the film layer 11 in the tire radial direction along the tire circumferential direction, air remaining between the film layer 11 and the carcass layer 4 is not removed. It is discharged to the tire cavity through the through hole 13 during tire molding. Therefore, when the temperature of the tire itself becomes high during traveling, the air pocket is prevented from expanding between the film layer 11 and the carcass layer 4, and the peeling of the film layer 11 during traveling is effectively prevented. be able to. In particular, since the temperature of a pneumatic tire for motor sports becomes high during running, it is effective to prevent the film layer 11 from peeling off due to the heat generation.

  Further, in the pneumatic tire for motor sports, the film layer 11 does not function as an air permeation preventing layer, but is provided for the purpose of improving the bladder slip during tire vulcanization and obtaining a reinforcing effect. Therefore, there is no problem even if a large number of through holes 13 are formed in the film layer 11.

  In the pneumatic tire, the maximum dimension D of each of the through holes 13 is preferably 0.1 mm to 1.0 mm. By setting the maximum dimension D of each of the through holes 13 within the above range, it is possible to sufficiently secure the tire rigidity while effectively preventing peeling of the film layer 11. If the maximum dimension D of the through-hole 13 is smaller than 0.1 mm, the air escape becomes worse, and if it is larger than 1.0 mm, the tire rigidity decreases. The shape of the through hole 13 is not particularly limited, and may be, for example, a circle, an ellipse, an oval, a rectangle, a polygon, or the like. When the through hole 13 is circular, the maximum dimension D is a diameter. When the through-hole 13 is elliptical or oval, the maximum dimension D is the major axis. The through-hole 13 can be formed in a desired region of the film layer 11 by performing a precking process on the film layer 11 at a material stage before the tire molding step, for example.

Further, the number of through-holes 13 per 100 cm ² in at least a part of the region where the through-holes 13 are formed is preferably 1 to 400. By setting the arrangement number of the through holes 13 per 100 cm ² within the above range, it is possible to sufficiently secure the tire rigidity while effectively preventing the film layer 11 from peeling off. If the number of through-holes 13 per 100 cm ² is less than one, air leakage will be poor, and if it is more than 400, tire rigidity will decrease.

  In the above-described embodiment, a pneumatic tire for motor sports has been described. However, the present invention can be applied to a pneumatic tire for uses other than motor sports. A pneumatic tire for applications other than motor sports usually requires a long-term air holding ability, but the film layer 11 having the through holes 13 does not sufficiently function as an air permeation preventing layer. Therefore, such a pneumatic tire needs to include an air permeation preventing layer extending along the carcass layer 4 in addition to the reinforcing film layer 11.

  Hereinafter, the film layer 11 used in the present invention will be described. The film layer 11 can be composed of a thermoplastic resin or a thermoplastic elastomer composition in which a thermoplastic resin and an elastomer are blended.

  Examples of the thermoplastic resin used in the present invention include polyamide resins [for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), and the like. Nylon 610 (N610), Nylon 612 (N612), Nylon 6/66 copolymer (N6 / 66), Nylon 6/66/610 copolymer (N6 / 66/610), Nylon MXD6 (MXD6), Nylon 6T , Nylon 6 / 6T copolymer, Nylon 66 / PP copolymer, Nylon 66 / PPS copolymer] and N-alkoxyalkylated products thereof (for example, methoxymethylated nylon 6, Nylon 6/610 copolymer) Methoxymethylated product of nylon 612], polyester-based resin [for example, Butylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimide diacid / Aromatic polyesters such as polybutylene terephthalate copolymer), polynitrile resins [eg, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), (meth) acrylonitrile / styrene copolymer, (Meth) acrylonitrile / styrene / butadiene copolymer], polymethacrylate-based resin [for example, polymethyl methacrylate (PMMA), polyethyl methacrylate], polyvinyl-based resin [for example, Vinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer Coalescence, vinylidene chloride / acrylonitrile copolymer], cellulosic resin [eg, cellulose acetate, cellulose acetate butyrate], fluororesin [eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene ( PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE)], imide-based resin [eg, aromatic polyimide (PI)] and the like can be preferably used.

  Examples of the elastomer used in the present invention include diene rubbers and hydrogenated products thereof (for example, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), butadiene rubber ( BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin-based rubber [eg, ethylene propylene rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (M- EPM), butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer], halogen-containing rubber [eg, Br-IIR, Cl-IIR, isobutylene paramethylstyrene copolymer] Combined bromide (Br-IPMS), chloroprene rubber (CR , Hydrin rubber (CHR), 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] , Methylphenylvinyl silicone rubber], sulfur-containing rubber [e.g., polysulfide rubber], fluorine rubber [e.g., vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing rubber Phosphazene-based rubbers), thermoplastic elastomers [eg, styrene-based elastomers, olefin-based elastomers, ester-based elastomers, urethane-based elastomers, polyamide-based elastomers] and the like can be preferably used. .

  When the compatibility between the specific thermoplastic resin and the elastomer is different, the two can be made compatible with each other by using an appropriate compatibilizer as the third component. By mixing the compatibilizer with the blend system, the interfacial tension between the thermoplastic resin and the elastomer decreases, and as a result, the rubber particles forming the dispersed phase become finer, so that the properties of both components become more It will be effectively expressed. Such a compatibilizer is generally a copolymer having a structure of both or one of a thermoplastic resin and an elastomer, or an epoxy group, a carbonyl group, a halogen group, an amino group capable of reacting with the thermoplastic resin or the elastomer. , An oxazoline group, a hydroxyl group or the like. These may be selected according to the type of thermoplastic resin and elastomer to be mixed, and commonly used ones include styrene / ethylene / butylene block copolymer (SEBS) and its maleic acid-modified product, EPDM, EPM, Examples include EPDM / styrene or EPDM / acrylonitrile graft copolymers and their maleic acid-modified products, styrene / maleic acid copolymers, and reactive phenoxines. The amount of the compatibilizer 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 (the total of the thermoplastic resin and the elastomer).

  In the thermoplastic elastomer composition, the composition ratio of the specific thermoplastic resin and the elastomer is not particularly limited, and is appropriately determined so as to take a structure in which the elastomer is dispersed as a discontinuous phase in a matrix of the thermoplastic resin. The preferred range is 90/10 to 15/85 by weight.

  In the present invention, the thermoplastic resin and the thermoplastic elastomer composition constituting the film can be mixed with another polymer such as a compatibilizer. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin and the elastomer, to improve the moldability of the material, to improve the heat resistance, to reduce the cost, etc. Examples of the material to be used include polyethylene (PE), polypropylene (PP), polystyrene (PS), ABS, SBS, polycarbonate (PC), and the like. In addition, fillers (calcium carbonate, titanium oxide, alumina, etc.) generally incorporated in polymer compounds, reinforcing agents such as carbon black and white carbon, softeners, plasticizers, processing aids, pigments, dyes, aging Inhibitors and the like can be optionally added.

  Further, the elastomer can be dynamically vulcanized when mixed with the thermoplastic resin. The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time) and the like for dynamically vulcanizing may be appropriately determined according to the composition of the elastomer to be added, and are not particularly limited.

  As the vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used. Specifically, examples of the sulfur-based vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, alkylphenol disulfide, and the like. 4 phr [herein, "phr" means parts by weight per 100 parts by weight of the elastomer component. same as below. ] Degree can be used.

  Examples of the organic peroxide vulcanizing agent include benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide, and 2,5-dimethyl-2,5-di (t-butyl peroxide). Oxy) hexane, 2,5-dimethylhexane-2,5-di (peroxyl benzoate) and the like are exemplified, and for example, about 1 to 20 phr can be used.

  Further, examples of the phenolic resin-based vulcanizing agent include brominated alkylphenol resins and mixed cross-linking systems containing halogen donors such as tin chloride and chloroprene and alkylphenol resins. For example, about 1 to 20 phr may be used. Can be.

  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- Examples thereof include dinitrosobenzene (about 2 to 10 phr) and methylene dianiline (about 0.2 to 10 phr).

  If necessary, a vulcanization accelerator may be added. Examples of the vulcanization accelerator include general vulcanization accelerators such as aldehyde / ammonia, guanidine, thiazole, sulfenamide, thiuram, dithioate, and thiourea, for example, About 2 phr can be used.

  Specifically, hexamethylenetetramine or the like is used as the aldehyde / ammonia vulcanization accelerator, diphenylguanidine is used as the guanidine vulcanization accelerator, and dibenzothiazyl disulfide is used as the thiazole vulcanization accelerator. DM), 2-mercaptobenzothiazole and its Zn salt, cyclohexylamine salt, etc., as sulfenamide-based vulcanization accelerators, cyclohexylbenzothiazylsulfenamide (CBS), N-oxydiethylenebenzothiazyl-2- Examples of thiuram-based vulcanization accelerators such as sulfenamide, Nt-butyl-2-benzothiazolesulfenamide, 2- (thymopolynyldithio) benzothiazole and the like include tetramethylthiuram disulfide (TMTD), tetraethyl Thiuram disulfide, tetrame Examples of dithioate vulcanization accelerators such as rutiuram monosulfide (TMTM) and dipentamethylenethiuram tetrasulfide include Zn-dimethyldithiocarbamate, Zn-diethyldithiocarbamate, Zn-di-n-butyldithiocarbamate, Zn -Ethylphenyldithiocarbamate, Te-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate, pipecoline pipecolyldithiocarbamate, etc., and thiourea-based vulcanization accelerators include ethylenethiourea, diethylthiourea and the like. be able to.

  In addition, as a vulcanization accelerating auxiliary, a general rubber auxiliary can be used in combination, for example, zinc white (about 5 phr), stearic acid, oleic acid, and a Zn salt thereof (about 2 to 4 phr). Etc. can be used.

The method for producing a thermoplastic elastomer composition is as follows: a thermoplastic resin and an elastomer (an unvulcanized product in the case of rubber) are melt-kneaded in a twin-screw kneading extruder or the like to form a thermoplastic resin which forms a continuous phase (matrix). By dispersing an elastomer therein as a dispersed phase (domain). When vulcanizing the elastomer, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer. The various additives (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer 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 and the elastomer is not particularly limited, and a screw extruder, a kneader, a Banbury mixer, a twin-screw kneader or the like can be used. Among them, for kneading the thermoplastic resin and the elastomer and for dynamic vulcanization of the elastomer, it is preferable to use a twin-screw kneading extruder. Further, two or more kinds of kneaders may be used and the kneading may be performed sequentially. As the conditions for the melt-kneading, the temperature may be at least the temperature at which the thermoplastic resin melts. Further, the shear rate at the time of kneading is preferably 1000 to 7500 sec ^-1 . The total kneading time is preferably 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after the addition is preferably 15 seconds to 5 minutes. The polymer composition produced by the above method may be formed into a desired shape by a usual thermoplastic resin molding method such as injection molding or extrusion molding.

  The thermoplastic elastomer composition thus obtained has a structure in which the elastomer is dispersed as a discontinuous phase in a matrix of the thermoplastic resin. By adopting such a structure, sufficient flexibility as a tire constituent member and sufficient rigidity can be provided by the effect of the resin layer as a continuous phase, and the thermoplastic resin can be used for molding regardless of the amount of the elastomer. Molding processability equivalent to that described above can be obtained.

  The Young's modulus of the thermoplastic resin and the thermoplastic elastomer composition in a standard atmosphere defined by JIS K7100 is not particularly limited, but is preferably 1 to 500 MPa, more preferably 50 to 500 MPa.

  The above-mentioned thermoplastic resin or thermoplastic elastomer composition can be formed into a sheet or film and used alone, but an adhesive layer may be laminated in order to enhance the adhesiveness with an adjacent rubber. Specific examples of the adhesive polymer constituting the adhesive layer include ultrahigh molecular weight polyethylene (UHMWPE) having a molecular weight of 1,000,000 or more, preferably 3,000,000 or more, ethylene ethyl acrylate copolymer (EEA), and ethylene methyl acrylate resin (EMA). ), Acrylate copolymers such as ethylene acrylic acid copolymer (EAA) and their maleic anhydride adducts, polypropylene (PP) and its maleic acid modified products, ethylene propylene copolymer and its maleic acid modified products, Polybutadiene-based resin and its maleic anhydride modified product, styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), fluorine-based thermoplastic resin, polyester-based thermoplastic resin, etc. Can be mentioned. These can be extruded by a conventional method, for example, by a resin extruder and formed into a sheet or film. The thickness of the adhesive layer is not particularly limited, but is preferably as small as possible for reducing the weight of the tire, and is preferably 5 μm to 150 μm.

A ring-shaped tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed inside the sidewall portion in the tire radial direction. In a pneumatic tire for motor sports provided with, a reinforcing film layer made of a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin is disposed on the inner surface of the tire, and a plurality of through-holes are formed in the entire area of the film layer. The tires of Examples 1 to 13 were manufactured in which the maximum dimension D of the through-holes and the number of the through-holes per 100 cm ² were varied as shown in Tables 1 and 2. The tire size was 330 / 710R18 for the front and 330 / 710R17 for the rear.

  For comparison, a tire of Conventional Example 1 having the same structure as in Examples 1 to 13 except that a butyl rubber layer having no through hole was disposed on the inner surface of the tire instead of the film layer, and a film layer having no through hole were used. A tire of Conventional Example 2 having the same structure as Examples 1 to 13 except that it was arranged on the inner surface of the tire was prepared.

  These test tires were evaluated for tire weight, steering stability, running time, and peeling resistance by the following evaluation methods, and the results are shown in Tables 1 and 2.

Tire weight:
The weight of each test tire was measured. The evaluation results were shown as index values using the reciprocal of the measured values assuming that Conventional Example 1 was 100. The larger the index value, the lighter the weight.

Driving stability:
Each test tire was mounted on a standard rim, and was mounted on a test vehicle at an air pressure of 130 kPa, and sensory evaluation was performed by a test driver at a circuit. The evaluation results were shown as index values with Conventional Example 1 being 100. The larger the index value, the better the steering stability.

Running time:
Each test tire was mounted on a standard rim and mounted on a test vehicle at an air pressure of 130 kPa. A test run was performed by a test driver at a circuit, and the running time of 5 laps excluding the first and last laps out of 7 laps was measured. The evaluation results were shown as index values using the reciprocal of the measured values assuming that Conventional Example 1 was 100. The larger the index value, the shorter the running time.

Peeling resistance:
Each test tire was mounted on a standard rim and mounted on a test vehicle at an air pressure of 130 kPa. After running at an average speed of 150 km / h for 50 minutes, the area of the portion where the film layer was peeled was measured. Evaluation of the peeling resistance was performed only for Conventional Example 2 and Examples 1 to 13 each having a film layer. The evaluation result was represented by an index using the reciprocal of the measured value, with Conventional Example 2 being 100. The larger the index value, the better the peeling resistance.

  As is clear from Tables 1 and 2, the tires of Examples 1 to 13 were lighter, more excellent in steering stability, and shorter in circuit running time compared to Conventional Example 1. Further, the tires of Examples 1 to 13 were able to prevent peeling of the film layer during running as compared with Conventional Example 2. In particular, Examples 1 to 5 exhibited good results.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Organic fiber reinforcement layer 8 Belt layer 8 Belt cover layer 10 Inner liner layer 11 Film layer 12 Tie rubber layer 13 Through hole

Claims (3)

  A ring-shaped tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed inside the tire radial direction of these sidewall portions. In the pneumatic tire provided, a film layer made of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is blended in a thermoplastic resin is disposed on the tire inner surface, and at least a part of the film layer in the tire radial direction. A pneumatic tire, wherein a plurality of through holes are formed in a region along a tire circumferential direction.   The pneumatic tire according to claim 1, wherein the maximum dimension of each of the through holes is 0.1 mm to 1.0 mm. 3. The pneumatic tire according to claim 1, wherein the number of the through-holes per 100 cm ² in at least a part of the region where the through-holes are formed is 1 to 400. 4.

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