JP2012250635A - Pneumatic tire and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which is easily manufactured, and which surely reduces cavernous resonance, and a method for manufacturing the same.SOLUTION: The pneumatic tire includes: a tread section 1; a pair of sidewall sections 2; a pair of bead sections 3; a carcass 5 comprising a carcass ply toroidally extended between bead cores 4 embedded in each of the bead sections 3 respectively; and an inner liner 9 disposed on the inner peripheral surface side of the tire and made of a resin. The pneumatic tire is characterized in that short fibers are fixed to the inner peripheral surface side of the inner liner 9.

Description

  The present invention relates to a pneumatic tire and a method for manufacturing the same, and more particularly to a pneumatic tire with reduced cavity resonance noise and a method for manufacturing the same.

One of the causes of noise generated by a pneumatic tire during travel is a cavity resonance caused by the length of the circular pipe inside the tire. This cavity resonance sound is generated when the tread portion vibrates due to the unevenness of the road surface when the tire rolls, and when the vibration of the tread portion vibrates the air inside the tire.
The cavity resonance frequency is 200 to 270 Hz from the circumference of any tire for passenger cars, and when transmitted to the axle, it contributes to unpleasant vehicle interior noise with a sharp peak different from other bands. ing.

  Since the cause of the cavity resonance frequency is the resonance of air inside the tire, a method of absorbing sound inside the tire is effective. For example, a method of arranging a sound absorbing material such as urethane on the inner surface of the tire, or a patent document A method of adhering short fibers to the tire inner peripheral surface as described in 1 is proposed.

However, it is common to provide a rubber inner liner on the inner peripheral surface of the tire. In this case, it is necessary to apply a release material such as silicon to the inner peripheral surface in the vulcanization molding process. In order to fix the fibers, it was necessary to remove the release agent after vulcanization.
In addition, when short fibers are bonded before vulcanization molding, a release material is applied after bonding, so that the release material adheres to the short fibers and the like and the sound absorption effect is reduced, and the cavity resonance noise may not be sufficiently reduced. was there.

JP 2004-82387 A

  In particular, an object of the present invention is to provide a pneumatic tire that can be easily manufactured and can reliably reduce cavity resonance noise, and a method for manufacturing the same.

  A pneumatic tire according to the present invention includes a tread portion, a pair of sidewall portions, a pair of bead portions, and a single carcass ply extending in a toroid shape between bead cores embedded in each bead portion. A carcass and an inner liner made of resin disposed on the inner peripheral surface side of the tire, comprising short fibers fixed to the inner peripheral surface side of the tire of the inner liner It is what.

Here, the “inner peripheral surface of the tire” refers to the inner surface of the tire body that comes into contact with the air chamber when the tire body is mounted on the outer periphery of the rim, and other layers such as an inner liner are formed on the inner side in the tire radial direction. In the case where it is provided, the inner surface in the tire radial direction of the tire body in contact with the air chamber including these layers is used.
“Short fiber is fixed” means that a part of the short fiber is firmly fixed to the inner peripheral surface of the tire, and the other part is attached so as to be able to move freely.

In such a pneumatic tire, more preferably, the resin comprises a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene-vinyl alcohol copolymer and an epoxy compound.
Preferably, the short fibers are fixed with an adhesive.

  Preferably, the area of the region of the short fibers fixed to the tire inner peripheral surface is 25% or more with respect to the surface area of the tire inner peripheral surface. Preferably, 100 or more are provided per square centimeter in a region where the short fibers are fixed to the inner peripheral surface of the tire. More preferably, the average length is in the range of 0.5 to 10 mm, and the average diameter is preferably in the range of 1 to 500 μm.

  Preferably, the region where the short fibers are fixed is composed of short fiber groups, and the plurality of short fiber groups are fixed independently of each other.

  By the way, as a manufacturing method of such a pneumatic tire, it has the process of apply | coating an adhesive agent to the tire inner peripheral surface side of an inner liner, and the process of making a short fiber adhere to the site | part which applied the adhesive agent.

  Preferably, the short fibers are provided on the tire inner peripheral surface by electrostatic flocking.

  In the pneumatic tire of the present invention, the short fibers are fixed to the inner peripheral surface side of the inner liner so that these short fibers are attached to the inner peripheral surface of the air chamber formed when the tire is attached to the rim. As will be provided, these short fibers can absorb the cavity resonance sound and consequently reduce the noise caused by the cavity resonance phenomenon.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view in the width direction illustrating one embodiment of a pneumatic tire according to the present invention with respect to a half portion of a tire in a tire posture before assembly to an applied rim. (A)-(c) It is a figure which shows typically the adhesion pattern of the short fiber used by this invention, respectively. It is a figure which shows typically the measurement of the axial force of the tire used in the Example. It is a figure which shows the measurement result in an Example.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
In the figure, 1 is a tread portion, 2 is a pair of side wall portions extending radially inward continuously to the respective side portions of the tread portion 1, and 3 is continuously inward in the radial direction of the sidewall portion 2. Each bead portion is shown.

The illustrated pneumatic tire extends in a toroid shape between a pair of bead portions 3 and bead cores 4 embedded in each bead portion 3, and folds around each bead core 4 from the inner side to the outer side in the tire width direction. A carcass 5 made of a single carcass ply is provided.
Here, the carcass ply can be formed by a ply cord such as an organic fiber extending in a direction orthogonal to the tire circumferential direction.

  In the figure, a belt 6 consisting of three belt layers and a tread rubber 7 are arranged on the outer side in the radial direction of the carcass 5, and the surface of the tread rubber 7 is omitted in the figure. A plurality of circumferential grooves and the like extending in the tire circumferential direction are formed.

  In the sidewall portion 2 and the bead portion 3, the outer surface of the carcass 5 in the tire width direction is covered with a side rubber 8 disposed along the outer surface.

  An inner liner 9 is disposed on the inner peripheral surface side of the tire, and the inner liner 9 can maintain the internal pressure in the tire so that air or the like does not leak.

  And innumerable short fibers 10 are fixed to the inner peripheral surface side of such an inner liner 9 substantially at right angles to the inner peripheral surface of the tire.

Here, the inner liner 9 needs to have resin as a main component from a viewpoint of improving gas barrier property.
Here, examples of the resin include polyamide resins such as nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66, nylon 6/66/610, nylon MXD6; Polyester resins such as polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyetherimide (PEI), polyaryl ester (PAR), polybutylene naphthalate (PBN); polynitrile resin; polymethacrylate resin; ethylene -Polyvinyl resins such as vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), and polyvinyl chloride (PVC). Among the, from the viewpoint of flexibility and gas barrier properties, the ethylene - vinyl alcohol copolymer is preferred. In addition, the resin which can be used for these resins may be used individually by 1 type, and may be used in combination of 2 or more type.

  More preferably, the resin is a modified ethylene-vinyl alcohol copolymer (C) obtained by reacting an ethylene-vinyl alcohol copolymer (A) with an epoxy compound (B).

Since the resin comprises a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene-vinyl alcohol copolymer and an epoxy compound, the elastic modulus of the ethylene-vinyl alcohol copolymer can be greatly reduced. The internal pressure retention can be greatly improved by improving the breakability at the time of bending and the degree of occurrence of cracks.
Further, the short fibers can be reliably bonded to the inner peripheral surface of the tire without applying a release material in the vulcanization molding step as in a tire having a normal rubber inner liner. For this reason, it is not necessary to remove the mold release agent after the vulcanization molding, and the production becomes easy.

Here, as ethylene-vinyl alcohol copolymer (A), Preferably ethylene content is 25-50 mol%. From the viewpoint of obtaining good bending resistance and fatigue resistance, the lower limit of the ethylene content is more preferably 30 mol% or more, and further preferably 35 mol% or more. From the viewpoint of gas barrier properties, the upper limit of the ethylene content is more preferably 48 mol% or less, and still more preferably 45 mol% or less.
When the ethylene content is less than 25 mol%, the bending resistance and fatigue resistance may be deteriorated or the melt moldability may be deteriorated, whereas when it exceeds 50 mol%, the gas barrier property tends to be insufficient.

The saponification degree of the ethylene-vinyl alcohol copolymer (A) is preferably 90% or more. The saponification degree is more preferably 95% or more, further preferably 98% or more, and optimally 99% or more.
If the degree of saponification is less than 90%, the gas barrier properties of the inner liner and the thermal stability during molding may be insufficient.

  A suitable melt flow rate (MFR) (190 ° C., under a load of 2160 g) of the ethylene-vinyl alcohol copolymer (A) is 0.1 to 30 g / 10 minutes, and more preferably 0.3 to 25 g / 10 minutes. However, when the melting point of the ethylene-vinyl alcohol copolymer (A) is around 190 ° C. or exceeds 190 ° C., it is measured at a plurality of temperatures above the melting point under a load of 2160 g, and the horizontal axis indicates the reciprocal absolute temperature in a semi-logarithmic graph. The logarithm of MFR is plotted on the vertical axis and expressed as a value extrapolated to 190 ° C.

  The epoxy compound (B) is not particularly limited, but is preferably a monovalent epoxy compound. When the epoxy compound is divalent or higher, a cross-linking reaction with the ethylene-vinyl alcohol copolymer (A) may occur, and the quality of the inner liner may be deteriorated due to the generation of gels and blisters. From the viewpoint of ease of production of the modified ethylene-vinyl alcohol copolymer (C), gas barrier properties, flex resistance and fatigue resistance, preferred monovalent epoxy compounds include glycidol and epoxypropane.

  The modified ethylene-vinyl alcohol copolymer (C) is preferably obtained by reacting 1 to 50 parts by weight of the epoxy compound (B) with 100 parts by weight of the ethylene-vinyl alcohol copolymer (A). More preferably, the mixing ratio of (A) and (B) is (B) 2 to 40 parts by weight with respect to (A) 100 parts by weight, and more preferably (A) with respect to 100 parts by weight (B ) 5 to 35 parts by weight.

  The method for producing the modified ethylene-vinyl alcohol copolymer (C) by reacting the ethylene-vinyl alcohol copolymer (A) with the epoxy compound (B) is not particularly limited, but the ethylene-vinyl alcohol copolymer ( A suitable method is a production method in which A) and the epoxy compound (B) are reacted in a solution.

  In the production method by solution reaction, the modified ethylene-vinyl alcohol copolymer (C) is obtained by reacting the epoxy compound (B) with the solution of the ethylene-vinyl alcohol copolymer (A) in the presence of an acid catalyst or an alkali catalyst. can get. The reaction solvent is preferably a polar aprotic solvent which is a good solvent for the ethylene-vinyl alcohol copolymer (A) such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone. Reaction catalysts include acid catalysts such as p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid and boron trifluoride, and alkali catalysts such as sodium hydroxide, potassium hydroxide, lithium hydroxide and sodium methoxide. Is mentioned. Of these, it is preferable to use an acid catalyst. As a catalyst amount, about 0.0001-10 weight part is suitable with respect to 100 weight part of ethylene-vinyl alcohol copolymers (A). The modified ethylene-vinyl alcohol copolymer (C) can also be produced by dissolving the ethylene-vinyl alcohol copolymer (A) and the epoxy compound (B) in a reaction solvent and performing a heat treatment.

  The melt flow rate (MFR) of the modified ethylene-vinyl alcohol copolymer (C) (190 ° C., under a load of 2160 g) is not particularly limited, but from the viewpoint of obtaining good gas barrier properties, flex resistance and fatigue resistance. The melt flow rate (MFR) of the modified ethylene-vinyl alcohol copolymer (C) is preferably 0.1 to 30 g / 10 minutes, more preferably 0.3 to 25 g / 10 minutes, More preferably, it is 5 to 20 g / 10 min. However, when the melting point of the modified EVOH is around 190 ° C. or exceeds 190 ° C., it is measured under a load of 2160 g and at a plurality of temperatures above the melting point, and the reciprocal absolute temperature is plotted on the horizontal axis and the logarithm of MFR is plotted on the vertical axis The value is plotted and extrapolated to 190 ° C.

  The modified ethylene-vinyl alcohol copolymer (C) is preferably crosslinked. When the modified ethylene-vinyl alcohol copolymer (C) is not crosslinked, the layer made of the modified ethylene-vinyl alcohol copolymer (C) is significantly deformed and uniform in the vulcanization process for producing a pneumatic tire. The layer cannot be retained, and the gas barrier property, flex resistance, and fatigue resistance of the inner liner may be deteriorated.

  The method for forming a crosslinked structure in the modified ethylene-vinyl alcohol copolymer (C) is not particularly limited, but a preferable method is a method of irradiating energy rays. Examples of the energy rays include ionizing radiation such as ultraviolet rays, electron beams, X-rays, α rays, and γ rays, and electron beams are preferable.

  With respect to the electron beam irradiation method, a method of introducing a molded body into an electron beam irradiation apparatus and irradiating an electron beam after film and sheet processing by extrusion molding can be mentioned. Although it does not specifically limit regarding the dose of an electron beam, Preferably it exists in the range of 10-60 Mrad. When the electron dose to irradiate is lower than 10 Mrad, it becomes difficult to crosslink. On the other hand, when the electron dose to be irradiated exceeds 60 Mrad, the molded body tends to deteriorate. More preferably, the electron dose range is 20 to 50 Mrad.

The inner liner 9 preferably has an oxygen permeation amount of 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less at 20 ° C. and 65 RH%, and is 1.0 × 10 ⁻¹² cm ³ · cm. / Cm ² · sec · cmHg or less, more preferably 5.0 × 10 ⁻¹³ cm ³ · cm / cm ² · sec · cmHg or less.

  The modified ethylene-vinyl alcohol copolymer (C) is formed into a film, a sheet or the like by melt molding in order to be used as the inner liner 9 for a pneumatic tire. Moreover, extrusion molding etc. are mentioned as melt molding methods, such as a film and a sheet | seat. The method of extrusion molding is not particularly limited, and examples thereof include a T-die method and an inflation method. The melting temperature varies depending on the melting point of the copolymer, but is preferably about 150 to 270 ° C.

  The inner liner 9 is provided for a pneumatic tire as a multilayer structure including at least one layer made of a modified ethylene-vinyl alcohol copolymer (C), in addition to being provided for a pneumatic tire as a single-layer molded product. Can be done. In the present invention, the inner liner can include the auxiliary layer 11 made of an elastomer adjacent to the layer made of the modified ethylene-vinyl alcohol copolymer (C).

  The inner liner 9 has a layer made of the modified ethylene-vinyl alcohol copolymer (C) bonded to an auxiliary layer 11 made of an elastomer such as butyl rubber or a diene elastomer via at least one adhesive layer. Can be done.

The inner liner 9 having gas barrier properties is composed of two layers, a layer made of a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene-vinyl alcohol copolymer and an epoxy compound, and a layer made of a resin containing thermoplastic polyurethane. A stacked structure in which the above is superposed can also be used.
With this structure, in addition to the gas barrier property by the inner liner 9, a multilayer structure having both high stretchability and thermoformability by a layer made of a resin containing thermoplastic polyurethane can be obtained.

Since the ethylene-vinyl alcohol copolymer has an —OH group, it is relatively easy to ensure adhesion with rubber. For example, if a chlorinated rubber / isocyanate adhesive is used for the adhesive layer, adhesion to the rubber composition used in the tire can be ensured.
As described above, the inner liner 9 including a layer made of resin can have various configurations. However, in order to greatly improve internal pressure retention, a layer made of resin on the innermost peripheral surface side of the inner liner 9. Are preferably arranged.

  The inner liner 9 preferably has a thickness of a layer made of the modified ethylene-vinyl alcohol copolymer (C) of 50 μm or less. When it exceeds 50 μm, the merit of weight reduction becomes smaller than the inner liner using butyl rubber, halogenated butyl rubber or the like currently used. Furthermore, the bending resistance and fatigue resistance of the layer made of the modified ethylene-vinyl alcohol copolymer (C) are lowered, and the bending deformation at the time of rolling of the tire is likely to cause breakage and cracking, and the crack is easy to extend. Therefore, the internal pressure retention after use of the tire may be lower than before use. On the other hand, it is preferable that it is 0.1 micrometer or more from a viewpoint of the gas barrier property of an inner liner. From the viewpoint of gas barrier properties, flex resistance, and fatigue resistance, the thickness of the layer made of the modified ethylene-vinyl alcohol copolymer (C) is more preferably 1 to 40 μm, and even more preferably 5 to 30 μm.

By the way, it is preferable that the area of the area | region where the short fiber 10 is being fixed to the tire internal peripheral surface of a short fiber is 25% or more with respect to the surface area of the internal peripheral surface of a tire.
With this configuration, the effect of reducing cavity resonance can be sufficiently exhibited.
In the case of a general tire for a passenger car, the weight of the short fiber for obtaining the sound absorption effect is sufficient to be about several tens of grams, and the influence on the tire weight can be almost ignored. In addition, since the amount used is small, the influence on the rotation balance can be ignored even if there is some unevenness in the adhesion of the short fibers.

  Preferably, the short fibers 10 can be provided with 100 or more per square centimeter in the region where the short fibers 10 are fixed to the tire inner peripheral surface, and this configuration is insufficient in reducing the cavity resonance. Therefore, the effect of reducing the cavity resonance can be sufficiently exhibited.

  And preferably, the short fiber 10 has an average length in the range of 0.5 to 10 mm. With this configuration, the effect of reducing the cavity resonance is sufficiently exhibited without the effect of reducing the cavity resonance being insufficient. be able to.

  That is, if the average length of the short fibers 10 is less than 0.5 mm, the cavity resonance noise may not be reduced. On the other hand, if the average length of the short fibers 10 exceeds 10 mm, the short fibers are easily entangled. As a result, workability deteriorates and uniform dispersion on the tire inner peripheral surface becomes difficult, and the sound absorption effect tends to be insufficient.

  Preferably, the short fiber 10 has an average diameter in the range of 1 to 500 μm. With this configuration, the effect of reducing the cavity resonance can be sufficiently exhibited without the effect of reducing the cavity resonance being insufficient.

  That is, when the average diameter of the short fibers 10 is less than 1 μm, yarn breakage frequently occurs in the manufacturing process of the short fibers 10, and the productivity of the short fibers 10 may be reduced. The weight tends to increase, which tends to affect the rotational balance of the tire.

  Preferably, the region to which the short fibers 10 are fixed is composed of short fiber groups, and a plurality of short fiber groups can be fixed independently of each other. With this configuration, the region to which the short fibers 10 are fixed By disposing them in a continuous manner, even if the adhesive layer may be peeled off, the peeling range is very small and the cavity resonance suppressing effect can be maintained.

  Such a short fiber 10 can be adhered to the inner peripheral surface of the tire by various methods, but it is preferable to use electrostatic flocking. Specifically, first, an adhesive is applied to the inner liner 9. The inner liner consisting of the inner liner 9 and the auxiliary layer 11 is manufactured by applying and bonding with the auxiliary layer 11 made of an elastomer such as butyl rubber or diene elastomer, and a tire is manufactured in a conventional manner using this inner liner. Next, an adhesive is applied to the inner peripheral surface side of the tire, and innumerable short fibers subjected to the electrodeposition treatment are attached to the tire by static electricity on the portion where the adhesive is applied, and the adhesive is applied to the portion where the adhesive is applied. Only the short fiber 10 is bonded and fixed.

  By the above-mentioned method, the innumerable short fibers 10 can be easily fixed to the inner peripheral surface side of the inner liner, and a pneumatic tire capable of obtaining a sound absorption effect can be efficiently manufactured.

Here, electrostatic flocking is a processing technology that charges short fibers and implants the short fibers vertically onto an object that has been pre-applied with an electrostatic force. Short fibers can be planted, which is suitable for planting short fibers on a tire inner circumferential surface having a three-dimensional curvature.
Further, in the electrostatic flocking process, the short fibers 30 can be uniformly attached in the circumferential direction, so that the rotational balance is not deteriorated.

  Such short fibers 10 can be organic synthetic fibers, inorganic fibers, regenerated fibers, natural fibers, and the like.

Examples of organic synthetic fibers include polyolefins such as polyethylene, polypropylene, and polybutylene, aliphatic polyamides such as nylon, aromatic polyamides such as Kevlar, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polyethylene succinate, and polymethylmethacrylate, and Shinji. Examples thereof include tactic-1,2-polybutadiene, acrylonitrile butadiene styrene copolymer, polystyrene, and copolymers thereof.
Examples of the inorganic fiber include carbon fiber and glass fiber.
Examples of the recycled fiber include rayon and cupra.
Examples of natural fibers include cotton, silk, wool, and the like.

  As schematically shown in FIGS. 2A to 2C, the short fibers 10 can be arranged in an adhesive pattern such as horizontal stripes, check and diagonal stripes, preferably (a) horizontal stripes, short The area for bonding the fibers can be widened, and the operation of applying the adhesive is simple.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

<Synthesis of modified ethylene-vinyl alcohol copolymer (C)>
A pressurized reaction vessel was charged with 2 parts by weight of an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 44 mol% and a saponification degree of 99.9% and 8 parts by weight of N-methyl-2-pyrrolidone at 120 ° C. The ethylene-vinyl alcohol copolymer (A) was completely dissolved by heating and stirring for 2 hours. To this was added 0.4 part by weight of glycidol as an epoxy compound (B), and then heated at 160 ° C. for 4 hours. After the heating, it was precipitated in 100 parts by weight of distilled water, and N-methyl-2-pyrrolidone and unreacted glycidol were sufficiently washed with a large amount of distilled water to obtain a modified ethylene-vinyl alcohol copolymer (C). . Further, the modified ethylene-vinyl alcohol copolymer (C) thus obtained was fined to a particle size of about 2 mm with a pulverizer, and then sufficiently washed with a large amount of distilled water again. The washed particles were vacuum-dried at room temperature for 8 hours, and then melted at 200 ° C. using a twin-screw extruder and pelletized.

Using the resulting modified ethylene-vinyl alcohol copolymer (C) pellets, the following extrusion was carried out using a 40 mmφ extruder (PLABOR GT-40-A manufactured by Plastics Engineering Laboratory) and a T-die film forming machine. A film was formed under the conditions to obtain a film-like inner liner having a thickness of 20 μm.
Type: Single screw extruder (non-vent type)
L / D: 24
Diameter: 40mmφ
Screw: Single-row full flight type, surface nitrided steel Screw rotation speed: 40rpm
Die: 550 mm wide coat hanger die Lip gap: 0.3 mm
Cylinder, die temperature setting: C1 / C2 / C3 / adapter / die = 180/200/210/210/210 (° C.)

A tire having a structure as shown in FIGS. 1 and 2 (a) and having a tire size of 195 / 65R15 is manufactured using the inner liner, and has a thickness of 15 denier (17 dtex) (φ45μ) and a length of 2 Cavity resonance sound was evaluated for each of the example tire and the comparative example tire in which about 30 g of a short fiber made of nylon of about 5 mm was flocked into an area of about tens of thousands of fibers / cm ² and about 75% of the inner peripheral surface of the tire. .
In addition, since the tire of a comparative example does not require modification about the tire structure except not providing a short fiber, it shall be based on an Example tire.

  A drum test having an iron plate surface with a diameter of 1.7 m at a speed of 80 km / h at a speed of 80 km / h with a filling internal pressure of 220 kPa, a load mass of 4.25 kN, assembled to a rim of 6JJ-15 for each of the example tire and the comparative example tire. The tire was rolled using a machine, and the vertical tire axial force was measured and evaluated by the method schematically shown in FIG. The resulting frequency spectrum is shown in FIG.

  From the results of FIG. 3, the peaks seen in the vicinity of 225 Hz and 240 Hz are due to cavity resonance, but a large reduction effect of 5 to 7 dB is obtained.

In addition, each of the example tire and the comparative example tire is assembled on a rim of 6JJ-15, the filling internal pressure is 220 kPa, equivalent to two passengers, mounted on a 2000 cc class passenger car, and rough at a vehicle speed of 50 km / h. We traveled on an asphalt road and measured noise at the driver's ear.
In this example as well, an equivalent cavity resonance effect could be confirmed.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass 6 Belt 7 Tread rubber 8 Side rubber 9 Inner liner 10 Short fiber 11 Auxiliary layer

Claims (10)

A tread portion, a pair of sidewall portions, a pair of bead portions, a carcass made of a single carcass ply extending in a toroid shape between bead cores embedded in each bead portion, and the inner peripheral surface side of the tire In a pneumatic tire comprising an inner liner including a resin layer disposed in
A pneumatic tire comprising short fibers fixed to a tire inner peripheral surface side of the inner liner.   The pneumatic tire according to claim 1, wherein the resin is a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene-vinyl alcohol copolymer and an epoxy compound.   The pneumatic tire according to claim 1, wherein the short fibers are fixed with an adhesive.   2. The pneumatic tire according to claim 1, wherein an area of the region of the short fibers fixed to the inner peripheral surface of the tire is 25% or more with respect to a surface area of the inner peripheral surface of the tire.   2. The pneumatic tire according to claim 1, wherein 100 or more of the short fibers are provided per square centimeter in a region where the short fibers are fixed to the inner peripheral surface of the tire.   The pneumatic tire according to claim 1, wherein the short fibers have an average length in a range of 0.5 to 10 mm.   The pneumatic tire according to claim 1, wherein the short fibers have an average diameter in a range of 1 to 500 μm.   The pneumatic tire according to claim 1, wherein the region where the short fibers are fixed is composed of a short fiber group, and the plurality of short fiber groups are fixed independently of each other. A tread portion, a pair of sidewall portions, a pair of bead portions, a carcass made of at least one carcass ply extending in a toroid shape between bead cores embedded in each bead portion, and an inner peripheral surface of the tire In the pneumatic tire provided with an inner liner made of resin disposed on the side,
A method for producing a pneumatic tire, comprising: a step of applying an adhesive to a tire inner peripheral surface side of an inner liner; and a step of adhering short fibers to a portion where the adhesive is applied.   The method for producing a pneumatic tire according to claim 9, wherein the short fibers are provided on the inner peripheral surface of the tire by electrostatic flocking.

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