JP5707031B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a pneumatic tire having an inner liner using a film layer on the inner surface and a method for manufacturing the same, and in particular, air that does not require a release agent to be applied to the inner surface when manufactured by a method using a bladder. TECHNICAL FIELD The present invention relates to a filled tire and a method for producing the pneumatic tire.

  Conventionally, an inner liner layer composed mainly of a low gas permeable butyl rubber such as butyl rubber or halogenated butyl rubber is disposed on the inner surface of a pneumatic tire in order to prevent air leakage and keep the tire air pressure constant. It is installed. However, if the content of these butyl rubbers is increased, the strength of the unvulcanized rubber is reduced, so that rubber breakage and sheet punching are likely to occur. Especially when the inner liner is made thinner, tire manufacturing There is a problem that the inner cord is easily exposed. For this reason, the content of butyl rubber is naturally limited, and when a rubber composition mainly composed of the butyl rubber is used for the inner liner, the air barrier property is maintained while maintaining the strength of the unvulcanized rubber. In order to ensure it, the thickness of the inner liner had to be around 1 mm. Therefore, the weight of the inner liner in the tire is about 5%, which is an obstacle to reducing the tire weight and improving the fuel efficiency of the automobile.

  In response to the recent social demand for energy saving, a method for reducing the thickness of the inner liner has been proposed for the purpose of reducing the weight of automobile tires. For example, instead of the conventional butyl rubber, an inner liner is proposed. A method using a nylon film layer or a vinylidene chloride layer as a liner has been proposed (see, for example, Patent Document 1 and Patent Document 2). In addition, it has been proposed to use a film of a composition made of a blend of a thermoplastic resin such as a polyamide-based resin or a polyester-based resin and an elastomer for the inner liner (see, for example, Patent Document 3).

  However, in the method using the above film, although the weight of the tire can be reduced to some extent, since the matrix material is a crystalline resin material, the resistance to cracking and resistance particularly when used at a low temperature of 5 ° C. or less. There is a drawback that the bending fatigue is inferior to the method using a layer of a rubber composition containing a normal butyl rubber, and the tire manufacturing process is complicated.

  On the other hand, an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is known to have excellent gas barrier properties. The EVOH has an air permeation amount that is 1/100 or less of the rubber composition for an inner liner in which a butyl rubber is blended. Therefore, even if the thickness is 50 μm or less, the internal pressure retention property of the tire can be greatly improved. In addition, the weight of the tire can be reduced. Therefore, it can be said that it is effective to use EVOH as a tire inner liner in order to improve the air permeability of the pneumatic tire. For example, a pneumatic tire having a tire inner liner made of EVOH is known (for example, , See Patent Document 4).

  However, when normal EVOH is used as the inner liner, the effect of improving the internal pressure retention of the tire is great, but normal EVOH has a significantly higher elastic modulus than rubber normally used for tires, so it is bent. It sometimes breaks or cracks occur due to deformation. Therefore, when the inner liner made of EVOH is used, the internal pressure retention before using the tire is greatly improved, but the internal pressure retention is lower than that before using the tire after being subjected to bending deformation during rolling of the tire. There was something to do.

  As a means for solving this problem, for example, a resin comprising an ethylene content of 20 to 70 mol%, an ethylene-vinyl alcohol copolymer having a saponification degree of 85% or more and 60 to 99 wt% and a hydrophobic plasticizer of 1 to 40 wt% A technique for using the composition in an inner liner is disclosed (see, for example, Patent Document 5). However, the bending resistance of such an inner liner is not always satisfactory.

  On the other hand, in general, vulcanization molding of a pneumatic tire is performed by setting an unvulcanized tire in a mold, inflating a bladder from the inside and pressing the unvulcanized tire against the inner surface of the mold. When a resin film is used for the inner liner, a release agent is usually applied to the inner surface of the tire to prevent air accumulation and film damage caused by the tire inner surface not slipping against the bladder during vulcanization molding. In addition, vulcanization molding is performed.

Japanese Patent Laid-Open No. 7-40702 JP-A-7-81306 JP-A-10-26407 JP-A-6-40207 JP 2002-52904 A

  However, when a release agent is applied during vulcanization molding of a tire, there are problems in that the manufacturing process becomes complicated and the manufacturing cost increases.

  Therefore, there is provided a pneumatic tire that does not cause air accumulation or film damage without applying a release agent to the tire inner surface when vulcanized using a bladder, and a method for manufacturing the pneumatic tire. It was hoped that.

An object of the present invention is to advantageously solve the above-mentioned problems, and the pneumatic tire of the present invention is composed of a film layer whose inner surface is irradiated with an electron beam at an irradiation dose of 50 to 600 kGy, and the film layer Comprises a resin film layer made of a resin film and an auxiliary layer made of an elastomer layer, and is located as an inner liner over the entire inner surface of the pneumatic tire, and the auxiliary layer is a region from the end of the belt of the tire to the bead portion. Of these, the thickness of the auxiliary layer in a portion corresponding to a radial width of at least 30 mm is 0.2 mm or more thicker than the thickness of the auxiliary layer in a portion corresponding to the lower portion of the belt. According to such a pneumatic tire, the portion located on the innermost side of the tire, that is, the portion where the bladder comes into contact when the unvulcanized tire is pressed against the mold using the bladder to form a vulcanization is 50 to 50. Since it consists of a film layer irradiated with an electron beam at an irradiation dose of 600 kGy, preferably 100 to 500 kGy, more preferably 150 to 400 kGy, the bladder can be applied without applying a release agent to the tire inner surface (film layer) during vulcanization molding. Slips smoothly against the inner surface of the tire, and air accumulation and film damage do not occur. Therefore, according to this invention, the pneumatic tire which can abbreviate | omit the application | coating process of the mold release agent to the tire inner surface at the time of manufacture can be provided. Note that the irradiation amount of the electron beam can be controlled by changing the acceleration voltage and the irradiation time.

Moreover, it is preferable that the pneumatic tire of this invention consists of a film layer whose inner surface has an elastic modulus of 20 to 1000 MPa. According to such a pneumatic tire, the portion located on the innermost side of the tire, that is, the portion where the bladder comes into contact when the unvulcanized tire is pressed against the mold using the bladder to form a vulcanization, is elastic. Since it consists of a 20 to 1000 MPa film layer, the bladder slips smoothly against the tire inner surface without applying a release agent to the tire inner surface (film layer) during vulcanization molding, and air accumulation and film damage may occur. Absent. Therefore , it is possible to provide a pneumatic tire capable of omitting the step of applying the release agent to the tire inner surface during manufacture. The elastic modulus is an SS curve measured at 23 ° C. and 150% RH using an autograph (AG-A500 type) manufactured by Shimadzu Corporation under the conditions of a distance between chucks of 50 mm and a tensile speed of 50 mm / min. The value obtained from the initial slope of the SS curve.

  Here, in the pneumatic tire of the present invention, it is preferable that the film layer does not contain a diene component. According to such a pneumatic tire, there is an effect that the reactivity with the bladder is poor and the crosslinking does not proceed (does not stick to the bladder). Here, the diene component refers to a compound having two double bonds, and specific examples include EPDM, NR, BR, SBR, RBR, NBR, CR, and IR.

In the pneumatic tire of the present invention, it is preferable that the film layer includes a single-layer or multilayer thermoplastic resin film layer. By making a film layer into a multilayer structure, the layer which bears each function (barrier property, protective property, etc.) requested | required of a film layer can be isolate | separated, and it can be set as the laminated body of the layer which has various functions. Specifically, for example, a laminate of a protective layer / barrier layer / protective layer can be formed.

In the pneumatic tire of the present invention, the oxygen permeation amount of the film layer at 20 ° C. and 65% RH is preferably 3.0 × 10 ⁻¹² cm ³ · cm ² · sec · cmHg or less. If a film layer having such an oxygen permeation amount is used, the gas barrier property on the inner surface of the tire will be sufficiently high, so that it is possible to provide a pneumatic tire with excellent internal pressure retention.

  In the pneumatic tire of the present invention, the film layer is obtained by reacting 1 to 50 parts by mass of an epoxy compound with 100 parts by mass of an ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 50 mol%. It is preferable to include a layer made of an ethylene-vinyl alcohol copolymer. The ethylene-vinyl alcohol copolymer has excellent gas barrier properties. However, the elastic modulus of the ethylene-vinyl alcohol copolymer can be greatly reduced by modification with an epoxy compound, and the rupture property and crack generation at the time of bending can be achieved. Since the degree can be improved, it is possible to provide a tire having excellent internal pressure retention when new and after running.

  In the pneumatic tire of the present invention, the film layer is obtained by reacting 1 to 50 parts by mass of an epoxy compound with 100 parts by mass of an ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 50 mol%. A layer composed of a resin composition in which a flexible resin or elastomer having a Young's modulus at 23 ° C. of 500 MPa or less is dispersed in a matrix composed of an ethylene-vinyl alcohol copolymer, and the flexible resin or elastomer is contained in the resin composition It is preferable that 10-80 mass% is contained. By including a layer made of a resin composition in which a Young's modulus is 500 MPa or less and a flexible resin or elastomer is dispersed, the elastic modulus of the film layer can be lowered, and as a result, the flex resistance of the pneumatic tire is improved. be able to.

  In the pneumatic tire of the present invention, the film layer is preferably crosslinked. By crosslinking the film layer, it is possible to prevent the film layer from being significantly deformed and maintaining a uniform layer in the vulcanization process when manufacturing a tire, and the gas barrier property, flex resistance, A pneumatic tire having excellent fatigue resistance can be provided.

  In the pneumatic tire of the present invention, the surface of the film layer is preferably composed of a layer of a thermoplastic urethane-based elastomer. When the film layer includes a resin film layer made of a resin film and an auxiliary layer, an inner liner having excellent bending resistance can be obtained by using an auxiliary layer made of a thermoplastic urethane-based elastomer as a surface layer of the film layer. The used pneumatic tire can be provided.

  The pneumatic tire of the present invention includes a laminate using the film layer and a rubber-like elastic layer adjacent to the film layer, and the rubber-like elastic layer uses butyl rubber or halogenated butyl rubber. It is preferable that Since butyl rubber and halogenated butyl rubber have low air permeability, the use of butyl rubber or halogenated butyl rubber for the rubber-like elastic layer can improve the internal pressure retention of the pneumatic tire. Moreover, it becomes easy to dispose the film layer on the tire inner surface.

  In the pneumatic tire of the present invention, the film layer and the rubber-like elastic body layer are preferably bonded using an adhesive layer made of an adhesive composition. If it does in this way, delamination between a film layer and a rubber-like elastic-body layer can be prevented reliably.

  Here, the adhesive composition contains a rubber component, and poly-p-dinitrosobenzene and 1,4-phenylene dimaleimide as a crosslinking agent and a crosslinking aid with respect to 100 parts by mass of the rubber component. It is preferable that it is a composition which mix | blended 0.1 mass part or more of at least 1 sort (s). This is because if the blending amount is less than 0.1 parts by mass, the peel resistance after vulcanization is not sufficient.

  Moreover, it is preferable that the said adhesive composition is a composition which contains a rubber component and 10 mass% or more of this rubber component consists of chlorosulfonated polyethylene. This is because a composition excellent in weather resistance, ozone resistance, heat resistance and the like can be obtained.

  The adhesive composition preferably includes a rubber component and is a composition in which 2 to 50 parts by mass of a filler is blended with 100 parts by mass of the rubber component. This is because when the blending amount of the filler is less than 2 parts by mass, the reinforcing effect is small, and when the blending amount is more than 50 parts by mass, the workability during blending is deteriorated. The filler is preferably carbon black. This is because the adhesive layer has excellent reinforcing properties.

  The adhesive composition preferably includes a rubber component, and 50% by mass or more of the rubber component is a composition composed of butyl rubber and / or halogenated butyl rubber. This is because butyl rubber or halogenated butyl rubber has low air permeability, and therefore, the internal pressure retention of a pneumatic tire can be improved by using butyl rubber or halogenated butyl rubber for the rubber-like elastic layer.

  The adhesive composition preferably contains a rubber component and is a composition in which 0.1 part by mass or more of a vulcanization accelerator is blended with 100 parts by mass of the rubber component. This is because if the amount is less than 0.1 parts by mass, the peel resistance is not sufficient.

The method for producing a pneumatic tire according to the present invention includes a step of placing an unvulcanized tire having an inner surface provided with a film layer irradiated with an electron beam at a dose of 50 to 600 kGy on a mold, and the unvulcanized tire. Installing a bladder inside the vulcanized tire, inflating the bladder, pressing the unvulcanized tire against a mold through the film layer, and vulcanizing the unvulcanized tire; The film layer includes a resin film layer made of a resin film and an auxiliary layer made of an elastomer layer, and is located as an inner liner over the entire inner surface of the pneumatic tire, the auxiliary layer being an end of the belt of the tire The thickness of the auxiliary layer in the portion corresponding to the radial width of at least 30 mm in the region from the bead portion to the bead portion is 0.2 mm or more thicker than the thickness of the auxiliary layer in the portion corresponding to the lower portion of the belt. A method for manufacturing a pneumatic tire, wherein a release agent is not used in the vulcanization molding step. According to such a method for manufacturing a pneumatic tire, the step of applying a release agent to the inner surface of the tire at the time of manufacture can be omitted without causing air accumulation or film breakage at the time of vulcanization molding.

The pneumatic tire manufacturing method of the present invention, it is preferable elastic modulus of the film layer is 20～1000MPa. According to such a method for manufacturing a pneumatic tire, the step of applying a release agent to the inner surface of the tire at the time of manufacture can be omitted without causing air accumulation or film breakage at the time of vulcanization molding.

  According to the pneumatic tire of the present invention, it is possible to provide a pneumatic tire that does not cause air accumulation or film damage without applying a release agent to the inner surface when vulcanized using a bladder. it can.

  Moreover, according to the manufacturing method of the pneumatic tire of this invention, it is providing the manufacturing method of the pneumatic tire which abbreviate | omitted the release process of the mold release agent to a tire inner surface without an air pool and film breakage occurring. it can.

It is a fragmentary sectional view of one embodiment of the pneumatic tire of the present invention. It is explanatory drawing explaining an example of the manufacturing method of the pneumatic tire of this invention, Fig.2 (a) shows the state which installed the unvulcanized tire in the metal mold | die, FIG.2 (b) shows the unvulcanized bladder. FIG. 2 (c) shows a state where the tire is vulcanized, and FIG. 2 (d) shows a state where the completed vulcanized tire is taken out.

  Below, the manufacturing method of the pneumatic tire of this invention and a pneumatic tire is demonstrated in detail. The pneumatic tire according to the present invention is characterized in that the inner surface is composed of a film layer irradiated with an electron beam at an irradiation dose of 50 to 600 kGy or a film layer having an elastic modulus of 20 to 1000 MPa.

<Film layer>
For the film layer, a film or sheet having an elastic modulus of 20 to 1000 MPa, for example, a polyamide resin, a polyvinylidene chloride resin, a polyester resin, an ethylene-vinyl alcohol copolymer resin, or the like can be used. Moreover, the film and sheet which irradiated the electron beam with the irradiation amount of 50-600 kGy with respect to the film and sheet which consist of those resin can also be used. Among them, as the film layer, a resin film having an oxygen transmission amount of 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less, for example, a film made of an ethylene-vinyl alcohol copolymer resin is preferably used. Can be used. Here, from the viewpoint of reducing the weight of the tire and the like, the thickness of the film layer is preferably 0.1 to 100 μm. In addition, a film and a sheet | seat can be produced by extrusion molding etc., for example.

  Further, a resin film that does not contain a diene component may be used for the film layer. Specifically, a polyamide resin, a polyester resin, an ethylene-vinyl alcohol copolymer resin, or the like can be suitably used for the film layer.

  Here, the ethylene-vinyl alcohol copolymer described above needs to have an ethylene content of 25 to 50 mol%. In order to obtain good bending resistance and fatigue resistance, the lower limit of the ethylene content is preferably 30 mol% or more, and more preferably 35 mol% or more. In order to obtain good gas barrier properties, the upper limit of the ethylene content is 48 mol% or less, and more preferably 45 mol% or less. If the ethylene content is less than 25 mol%, the bending resistance, fatigue resistance, and melt moldability may be deteriorated. If the ethylene content exceeds 50 mol%, the desired gas barrier may be obtained. There is a risk that sex may not be obtained.

  The saponification degree of the ethylene-vinyl alcohol copolymer is preferably 90% or more, more preferably 95% or more, still more preferably 98% or more, and optimally 99% or more. If the degree of saponification is less than 90%, the gas barrier properties and the thermal stability during film layer formation may be insufficient.

  The ethylene-vinyl alcohol copolymer preferably has a melt flow rate (MFR) of 190 ° C. and 0.130 g / 10 min under a load of 2160 g, more preferably 0.3 to 25 g / 10 min. preferable. For ethylene-vinyl alcohol having a melting point near 190 ° C. or 190 ° C. or higher, MFR is measured at a temperature equal to or higher than the melting point under a load of 2160 g. In the semilogarithmic graph, the reciprocal absolute temperature is plotted on the horizontal axis and the logarithm of MFR. A suitable ethylene-vinyl alcohol copolymer having a value plotted on the vertical axis and extrapolated to 190 ° C. is within the above range.

  The ethylene-vinyl alcohol copolymer-based resin has a Young's modulus at 23 ° C. of 500 MPa in a matrix composed of a modified ethylene-vinyl alcohol copolymer obtained by reacting an ethylene compound with an ethylene-vinyl alcohol copolymer. A resin composition in which the following flexible resin or elastomer is dispersed can be suitably used. If this resin composition is used, the elastic modulus of a film layer can be reduced, the bending resistance of a film layer can be improved, and the breakability at the time of bending of a film layer and the generation | occurrence | production degree of a crack can be improved.

  The flexible resin or elastomer preferably has a functional group that reacts with a hydroxyl group. When the flexible resin or elastomer has a functional group that reacts with a hydroxyl group, the flexible resin or elastomer is uniformly dispersed in the modified ethylene-vinyl alcohol copolymer. Here, examples of the functional group that reacts with a hydroxyl group include a maleic anhydride residue, a hydroxyl group, a carboxyl group, and an amino group. Specific examples of the flexible resin having a functional group that reacts with a hydroxyl group include maleic anhydride-modified hydrogenated styrene-ethylene-butadiene-styrene block copolymer, maleic anhydride-modified ultra-low density polyethylene, and the like. Furthermore, the flexible resin preferably has an average particle size of 2 μm or less. If the average particle size of the flexible resin exceeds 2 μm, the flex resistance of the film layer may not be sufficiently improved, which may result in a decrease in gas barrier properties and a deterioration in tire internal pressure retention properties. The average particle diameter of the flexible resin in the resin composition can be measured, for example, by freezing a sample, cutting the sample with a microtome, and observing it with a transmission electron microscope (TEM).

  Here, the content of the flexible resin or the elastomer in the resin composition is preferably in the range of 10 to 80% by mass. When the content of the flexible resin or elastomer is less than 10% by mass, the effect of improving the bending resistance is small. On the other hand, when the content exceeds 80% by mass, the gas barrier property may be deteriorated.

  The modified ethylene-vinyl alcohol copolymer is specifically 1 to 50 parts by mass, preferably 2 to 40 parts by mass, more preferably 100 parts by mass of the ethylene-vinyl alcohol copolymer. It can be obtained by reacting 5 to 35 parts by mass.

  Here, as an epoxy compound made to react with the said ethylene-vinyl alcohol copolymer, a monovalent | monohydric epoxy compound is preferable. A divalent or higher-valent epoxy compound may crosslink with the ethylene-vinyl alcohol copolymer to generate gels, blisters, and the like, thereby reducing the quality of the inner liner. Note that glycidol and epoxypropane are particularly preferable among the monovalent epoxy compounds from the viewpoints of ease of production of the modified ethylene-vinyl alcohol copolymer, gas barrier properties, flex resistance, and fatigue resistance.

  The production method of the modified ethylene-vinyl alcohol copolymer is not particularly limited, but a production method in which the ethylene-vinyl alcohol copolymer and the epoxy compound are reacted in a solution is preferable. More specifically, an epoxy compound is added to an ethylene-vinyl alcohol copolymer solution in the presence of an acid catalyst or an alkali catalyst, preferably in the presence of an acid catalyst, and the ethylene-vinyl alcohol copolymer and the epoxy compound are reacted. By doing so, a modified ethylene-vinyl alcohol copolymer can be produced. Here, examples of the reaction solvent include aprotic polar solvents such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Examples of the acid catalyst include p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, and boron trifluoride. Examples of the alkali catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, Examples include sodium methoxide. The catalyst amount is preferably in the range of 0.0001 to 10 parts by mass with respect to 100 parts by mass of the ethylene-vinyl alcohol copolymer.

  In addition to the above production method, the modified ethylene-vinyl alcohol copolymer may be produced by dissolving the ethylene-vinyl alcohol copolymer and the epoxy compound in a reaction solvent and then heat-treating the reaction solvent. Can do.

  From the viewpoint of obtaining good bending resistance and fatigue resistance, the modified ethylene-vinyl alcohol copolymer is not particularly limited, but the melt flow rate (MFR) is 190 ° C. and 0.1 to 30 g under a load of 2160 g. / 10 minutes, more preferably 0.3 to 25 g / 10 minutes, and still more preferably 0.5 to 20 g / 10 minutes. For modified ethylene-vinyl alcohol having a melting point near 190 ° C. or 190 ° C. or higher, MFR is measured under a load of 2160 g and at a temperature equal to or higher than the melting point. In the semi-logarithmic graph, the abscissa represents the reciprocal absolute temperature and the logarithm of MFR. Is plotted on the vertical axis and the value extrapolated to 190 ° C. falls within the above range is defined as a preferred modified ethylene-vinyl alcohol copolymer.

The film layer using the modified ethylene-vinyl alcohol copolymer preferably has an oxygen transmission rate at 20 ° C. and 65% RH of 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less. It is more preferably 1.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less, and it is preferably 5.0 × 10 ⁻¹³ cm ³ · cm / cm ² · sec · cmHg or less. Further preferred. When the oxygen permeation rate at 20 ° C. and 65% RH exceeds 3.0 × 10 ⁻¹² cm ³ · cm ² · sec · cmHg, the internal pressure retention of the tire is enhanced when the film layer is used as an inner liner. Therefore, the layer has to be thick, and the weight of the tire increases.

  The film layer using the modified ethylene-vinyl alcohol copolymer can be obtained by molding the modified ethylene-vinyl alcohol copolymer into a film or sheet by melt molding. Specifically, it can be produced using extrusion molding such as T-die method or inflation method. In addition, although the melting temperature at the time of melt molding changes with melting | fusing point etc. of the said modified ethylene-vinyl alcohol copolymer, 150 to 270 degreeC is preferable.

  The modified ethylene-vinyl alcohol copolymer is preferably crosslinked. When a non-crosslinked modified ethylene-vinyl alcohol copolymer is used for the film layer, the layer made of the modified ethylene-vinyl alcohol copolymer is remarkably deformed in the vulcanization process when manufacturing the tire, and a uniform layer is formed. The film layer cannot be maintained, and the gas barrier property, flex resistance, and fatigue resistance of the film layer may be deteriorated.

  Here, the crosslinking method of the modified ethylene-vinyl alcohol copolymer is not particularly limited, and examples thereof include a method of irradiating energy rays. Examples of the energy rays include ionizing radiations such as ultraviolet rays, electron beams, X-rays, α rays, and γ rays, and among these, electron beams are particularly preferable.

  The electron beam irradiation is preferably performed after the modified ethylene-vinyl alcohol copolymer is processed into a molded body such as a film or a sheet by the above-described method. Here, the dose of the electron beam irradiated for crosslinking is preferably in the range of 10 to 60 Mrad, and more preferably in the range of 20 to 50 Mrad. When the dose of the electron beam to be irradiated is less than 10 Mrad, the crosslinking is difficult to proceed. On the other hand, when the dose exceeds 60 Mrad, the molded body is likely to deteriorate.

  Moreover, the film layer used for the pneumatic tire of the present invention may have a laminated structure in which the above-described resin film or sheet is laminated, or a laminated structure in which the resin film or sheet and an auxiliary layer are laminated.

  Here, the auxiliary layer is preferably made of an elastomer, and as the auxiliary layer, for example, butyl rubber, a diene elastomer, or the like can be used.

  As the diene elastomer, natural rubber or butadiene rubber can be preferably used, but butyl rubber is more preferable, and halogenated butyl rubber is further preferable from the viewpoint of improving gas barrier properties.

  In addition, when cracks occur in the auxiliary layer, it is preferable to use a mixture of butyl rubber and a diene elastomer from the viewpoint of suppressing the extension of the cracks. By using such a mixture, the internal pressure retention property of the pneumatic tire can be kept high even when minute cracks are generated in the auxiliary layer.

  In addition, as the elastomer used for the auxiliary layer, a thermoplastic urethane-based elastomer is also preferable. If a thermoplastic urethane-based elastomer is used, the generation and extension of cracks in the auxiliary layer can be suppressed, and the auxiliary layer can be thinned to reduce the weight of the pneumatic tire. Here, when a thermoplastic urethane-based elastomer is used as an auxiliary layer, the surface layer of the film layer is more preferably an auxiliary layer of a thermoplastic urethane-based elastomer. This is because a pneumatic tire using a film layer having excellent bending resistance can be provided by using a thermoplastic urethane elastomer for the surface layer of the film layer.

  In addition, as an auxiliary | assistant layer, what laminated | multilayered the layer which consists of a layer which consists of a thermoplastic urethane type elastomer, and a butyl rubber and a diene type elastomer is more preferable.

The auxiliary layer preferably has an oxygen permeation amount of 3.0 × 10 ⁻⁹ cm ³ · cm / cm ² · sec · cmHg or less at 20 ° C. and 65% RH, and preferably 1.0 × 10 ⁻⁹ cm. More preferably, it is ³ · cm / cm ² · sec · cmHg or less. When the oxygen permeation amount at 20 ° C. and 65% RH is 3.0 × 10 ⁻⁹ cm ³ · cm ² / cm ² · sec · cmHg or less, the auxiliary layer also functions as an air barrier layer. A sufficient reinforcing effect is exerted on the tire, and when the film layer is used as an inner liner, it is possible to maintain high internal pressure retention of the tire. Furthermore, even if a crack occurs in the resin film, a good internal pressure can be maintained. In addition, as an auxiliary layer with low air permeability, there is an auxiliary layer using butyl rubber or halogenated butyl rubber.

  Further, the auxiliary layer preferably has a tensile stress at 300% elongation of 10 MPa or less, more preferably 8 MPa or less, and even more preferably 7 MPa or less in order to prevent generation of cracks and growth. . This is because if the tensile stress at 300% elongation exceeds 10 MPa, the bending resistance and fatigue resistance of the film layer when the auxiliary layer is used may be lowered.

  Here, the resin film and the auxiliary layer can be bonded together via at least one adhesive layer. In addition, when using ethylene-vinyl alcohol copolymer for a resin film, since ethylene-vinyl alcohol copolymer has OH group, adhesion with an auxiliary | assistant layer can be performed easily. Examples of the adhesive used for the adhesive layer include a chlorinated rubber / isocyanate adhesive.

  In addition, the method for producing the film layer is not particularly limited. For example, an elastomer for forming an auxiliary layer on a molded article (resin film) such as a film or sheet made of a modified ethylene-vinyl alcohol copolymer. And a method of melt-extruding an adhesive layer, a method of melt-extruding a modified ethylene-vinyl alcohol copolymer and an adhesive layer on an elastomer base material forming an auxiliary layer, a modified ethylene-vinyl alcohol copolymer, and an auxiliary layer And, if necessary, a method of co-extrusion with an adhesive layer, a method of bonding a molded product obtained from a modified ethylene-vinyl alcohol copolymer and an auxiliary layer using an adhesive layer, and a tire molding A molded product obtained from the modified ethylene-vinyl alcohol copolymer on the drum, an auxiliary layer, and an adhesive layer as necessary. Method and the like to match Ri, and the like.

  And when laminating | stacking a resin film or sheet | seat and an auxiliary | assistant layer to make a film layer, it is preferable that a resin film consists of a modified ethylene-vinyl alcohol copolymer, and the thickness is 0.1 micrometer or more and 100 micrometers or less It is preferable that it is 1-40 micrometers, and it is still more preferable that it is 5-30 micrometers. Moreover, it is preferable that the sum total of the thickness of an auxiliary | assistant layer is 50-2000 micrometers, it is more preferable that it is 100-1000 micrometers, and it is still more preferable that it is 300-800 micrometers.

  This is because when the film layer having a resin film thickness exceeding 100 μm is used as the inner liner, the weight reduction effect is reduced as compared with the inner liner using butyl rubber or halogenated butyl rubber as the air barrier layer, and the resin film Since the bending resistance and fatigue resistance of the layer are reduced and the bending deformation is likely to cause breakage and cracking, and the generated cracks are easy to extend, internal pressure retention is maintained when running on a tire. It is because it may fall. When the thickness is less than 0.1 μm, sufficient gas barrier properties cannot be ensured.

  Further, when the total thickness of the auxiliary layers exceeds 2000 μm, the weight of the tire is increased, and when it is less than 50 μm, the bending resistance and fatigue resistance of the film layer are lowered and breakage and cracking are likely to occur. In addition, since cracks are easily extended, the internal pressure retention of a tire using the film layer may be reduced. In addition, it is difficult to make the total thickness of the auxiliary layers below the belt of the tire less than 50 μm from the viewpoint of manufacturing the tire.

<Inner liner>
The film layer disposed on the inner surface of the pneumatic tire of the present invention may itself be an inner liner or a part of the inner liner. Specifically, the pneumatic tire of the present invention is a laminate in which a film layer and a rubber-like elastic body layer made of a rubber-like elastic body are laminated, and the film layer is an inner surface of the tire. An inner liner may be disposed so as to be located on a surface that contacts the bladder during vulcanization molding of the tire.

  Here, the rubber-like elastic layer preferably contains butyl rubber or halogenated butyl rubber as a rubber component. Here, examples of the halogenated butyl rubber include chlorinated butyl rubber, brominated butyl rubber, and modified rubbers thereof. Commercially available products can be used as the halogenated butyl rubber. Examples of commercially available products include “Enjay Butyl HT10-66” (registered trademark) [manufactured by Enjay Chemical Co., Ltd., chlorinated butyl rubber], “Bromobutyl 2255”. "(Registered trademark) [manufactured by JSR Corporation, brominated butyl rubber]" and "Bromobutyl 2244" (registered trademark) [manufactured by JSR Corporation, brominated butyl rubber]. Examples of the chlorinated or brominated modified rubber include “Expro50” (registered trademark) [manufactured by Exxon Corporation].

  The content of butyl rubber and / or halogenated butyl rubber in the rubber component in the rubber-like elastic layer is preferably 50% by mass or more, and 70 to 100% by mass from the viewpoint of improving air permeation resistance. Is more preferable. Here, as the rubber component, diene rubber, epichlorohydrin rubber and the like can be used in addition to butyl rubber and halogenated butyl rubber. These rubber components may be used alone or in combination of two or more.

  Specific examples of the diene rubber include natural rubber (NR), isoprene rubber (IR), cis-1,4-polybutadiene (BR), syndiotactic-1,2-polybutadiene (1,2BR), and styrene. -Butadiene copolymer rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), etc. are mentioned. These diene rubbers may be used alone or in combination of two or more.

  In addition to the rubber component, the rubber-like elastic layer has a compounding agent usually used in the rubber industry, such as a reinforcing filler, a softening agent, an anti-aging agent, a vulcanizing agent, and a rubber vulcanization accelerator. , A scorch inhibitor, zinc white, stearic acid and the like can be appropriately blended depending on the purpose. As these compounding agents, commercially available products can be suitably used.

  In the laminated body of the present invention, it is preferable that the film layer has a thickness of 200 μm or less and the rubber-like elastic layer has a thickness of 200 μm or more. Here, the lower limit of the thickness of the film layer is more preferably about 1 μm, further preferably in the range of 10 to 150 μm, and still more preferably in the range of 20 to 100 μm. When the thickness of the film layer exceeds 200 μm, when the laminate of the present invention is used as an inner liner, bending resistance and fatigue resistance are lowered, and breakage and cracking are likely to occur due to bending deformation at the time of tire rolling. . On the other hand, if it is less than 1 μm, gas barrier properties may not be sufficiently secured. In addition, when the thickness of the rubber-like elastic layer is less than 200 μm, the reinforcing effect is not sufficiently exhibited, and when the film layer is ruptured / cracked, it becomes easy for the crack to extend. Is difficult to suppress.

  Here, the film layer and the rubber-like elastic body layer can be joined via an adhesive layer made of an adhesive composition. And it is preferable that the thickness of an adhesive bond layer is the range of 5-100 micrometers. If the thickness of the adhesive layer is less than 5 μm, adhesion failure may occur, and if it exceeds 100 μm, the advantages of weight reduction and cost are reduced.

  Examples of the adhesive composition include chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, and diene rubber. Among these, chlorosulfonated polyethylene and butyl rubber and / or halogenated butyl rubber are preferable.

  Here, when the adhesive composition contains a rubber component such as butyl rubber, halogenated butyl rubber, or diene rubber as described above, poly-p-di-dioxide is used as a crosslinking agent and a crosslinking aid with respect to 100 parts by mass of the rubber component. More than 0.1 parts by mass of at least one of nitrosobenzene and 1,4-phenylene dimaleimide, 2 to 2 fillers such as carbon black, wet silica, aluminum hydroxide, aluminum oxide, magnesium oxide, montmorillonite and mica It is preferably a composition containing 50 parts by mass, 0.1 part by mass or more of a vulcanization accelerator such as a thiuram vulcanization accelerator and a dithiocarbamate vulcanization accelerator. The rubber component is preferably 10% by mass or more of chlorosulfonated polyethylene, and 50% by mass or more is preferably made of butyl rubber and / or halogenated butyl rubber.

  In addition, when the inner liner is disposed on the inner surface of the tire, the inner liner often breaks, cracks and cracks in the vicinity of the side portion of the tire that is greatly deformed by bending. Therefore, if the inner liner having a thick auxiliary layer in the portion corresponding to the inner portion of the side portion of the tire is used, the inner liner can be reduced in weight while further improving the internal pressure retention of the tire provided with the inner liner.

<Pneumatic tire>
The pneumatic tire according to the present invention includes, for example, a tread portion 1, a pair of bead portions 2, and a pair of sidewall portions extending between the tread portion 1 and each bead portion 2, as shown in FIG. 1. 3, a carcass 4 extending in a toroidal shape between the pair of bead portions 2 to reinforce these portions, and two belt layers disposed on the outer side in the tire radial direction of the crown portion of the carcass 4 The belt 5 is made of an inner liner 6 disposed inside the carcass 4. And the inner surface of this pneumatic tire consists of a film layer mentioned above.

  Here, in this pneumatic tire, the portion of the auxiliary layer corresponding to a radial width of at least 30 mm in the region from the end of the belt of the tire to the bead portion is the lower portion of the belt. It is preferable that the thickness of the auxiliary layer corresponding to is thicker by 0.2 mm or more. This is the region from the belt end to the bead portion where the strain is most severe and cracking is likely to occur. To improve the durability of such a region, it is effective to increase the thickness of the auxiliary layer in the specific region. Because.

  And this pneumatic tire can be manufactured as follows, for example.

  First, an upper mold 11 and a lower part of an unvulcanized tire 12 that has a film layer of an inner liner on the innermost surface and is produced by a normal method so that the tire axial direction is vertical without applying a release agent. It is installed between the molds 13 (see FIG. 2A). Here, a rod 16 is provided on the upper mold 11, and a cylinder 15 having a bladder 14 is provided below the lower mold 13. As the bladder 14, for example, a bladder as disclosed in Japanese Patent Application Laid-Open No. 2008-179676 can be used. Specifically, the bladder 14 is a rubber composition having a blended formulation of 95 parts by weight of butyl rubber, 5 parts by weight of chloroprene rubber, 48 parts by weight of carbon black, 5.5 parts by weight of resin, 8 parts by weight of castor oil, and 5 parts by weight of zinc white. It consists of a product vulcanized and molded by a conventional method.

  Next, the upper mold 11 is pushed down, and a heated fluid such as steam is supplied from the lower part of the cylinder 15 to lift the bladder 14, and the bladder 14 is installed inside the unvulcanized tire 12 (inside the film layer). (See FIG. 2 (b)).

  Thereafter, the upper mold 11 is further pushed downward using the rod 16 to bring the upper mold 11 and the lower mold 12 into close contact with each other, and the unvulcanized tire 12 is pressed against the mold with the bladder 14 expanded by supply of steam. (See FIG. 2 (c)). At this time, since the film layer described above is located on the inner surfaces of the bladder 14 and the unvulcanized tire 12, no air pool or film breakage occurs without using a release agent.

  Then, the unvulcanized tire 12 is vulcanized and formed into a vulcanized tire 17 by pressing the mold by the bladder 14 and the heat of the steam supplied to the bladder 14 (see FIG. 2D).

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail using an Example, this invention is not limited to these Examples at all.

<Production Example 1 Synthesis of Modified Ethylene-Vinyl Alcohol Copolymer>
2 parts by mass of ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% and a saponification degree of 99.9% (190 ° C., MFR under a load of 21.18 N: 5.5 g / 10 min) in a pressurized reaction vessel And 8 parts by mass of N-methyl-2-pyrrolidone were added and stirred at 120 ° C. for 2 hours to completely dissolve the ethylene-vinyl alcohol copolymer. After adding 0.4 parts by mass of epoxypropane as an epoxy compound, the mixture was heated at 160 ° C. for 4 hours. After the heating, it was precipitated in 100 parts by mass of distilled water, and N-methyl-2-pyrrolidone and unreacted epoxypropane were sufficiently washed with a large amount of distilled water to obtain a modified ethylene-vinyl alcohol copolymer. Furthermore, the obtained modified ethylene-vinyl alcohol copolymer 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 to be pelletized.

The ethylene content and saponification degree of the ethylene-vinyl alcohol copolymer were measured by ¹ H-NMR using deuterated dimethyl sulfoxide as a solvent [using “JNM-GX-500 type” manufactured by JEOL Ltd.] This is a value calculated from the spectrum obtained in (1). Also, the melt flow rate (MFR) of the ethylene-vinyl alcohol copolymer is such that a sample is filled in a cylinder having an inner diameter of 9.55 mm and a length of 162 mm of a melt indexer L244 [manufactured by Takara Kogyo Co., Ltd.] After melting, an even load was applied using a plunger having a weight of 2160 g and a diameter of 9.48 mm, and the amount of resin (g / g) extruded per unit time from a 2.1 mm diameter orifice provided in the center of the cylinder. 10 minutes). However, when the melting point of the ethylene-vinyl alcohol copolymer 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. Was plotted on the vertical axis, and the value calculated by extrapolating to 190 ° C. was taken as the melt flow rate (MFR).

<Production Example 2 Production of 3-layer film>
Using the modified EVOH obtained in Production Example 1 and thermoplastic polyurethane (TPU) [Kuraray Co., Ltd. Kuramylon 3190], using a two-kind three-layer coextrusion device, three layers under the following coextrusion molding conditions: A film layer having a structure (TPU layer / modified EVOH layer (resin film) / TPU layer) was prepared. The thickness of each layer is 20 μm for both the TPU layer and the modified EVOH layer.

Extrusion temperature of each resin: C1 / C2 / C3 / die = 170/170/220/220 ° C.
Extruder specifications for each resin:
Thermoplastic polyurethane: 25mmφ extruder P25-18AC [Osaka Seiki Machine Co., Ltd.]
Modified EVOH: 20 mmφ extruder lab machine ME type CO-EXT [manufactured by Toyo Seiki Co., Ltd.]
T-die specification: 500mm width, 2 types, 3 layers [Plastic Engineering Laboratory Co., Ltd.]
Cooling roll temperature: 50 ° C
Pickup speed: 4m / min

<Production Example 3 Production of Unvulcanized Rubber-like Elastic Layer>
A rubber composition having the following composition was prepared to prepare an unvulcanized rubber-like elastic sheet having a thickness of 500 μm.
(Rubber composition)
Natural rubber ... 30 parts by mass brominated butyl rubber [manufactured by JSR Corporation, Bromobutyl 2244] ... 70 parts by mass GPF carbon Black [Asahi Carbon Co., Ltd., # 55] ... 60 parts by mass SUNPAR2280 [Nihon Sun Oil Co., Ltd.] 7 mass parts stearic acid [Asahi Denka Kogyo Co., Ltd.]・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 1 parts by mass vulcanization accelerator [Noxeller DM, manufactured by Ouchi Shinsei Chemical Co., Ltd.] ・ 1.3 parts by mass of zinc oxide [manufactured by Shiramizu Chemical Co., Ltd.] ... 3 parts by mass sulfur [manufactured by Karuizawa Refinery] ... 0.5 parts by mass

<Production Example 4 Production of Unvulcanized Rubber-like Elastic Layer>
A rubber composition having the following composition was prepared to prepare an unvulcanized rubber-like elastic sheet having a thickness of 500 μm.
(Rubber composition)
Natural rubber: 100 parts by weight GPF carbon black [Asahi Carbon Co., Ltd., # 55] ... 60 parts by weight SUNPAR2280 [Nippon Sun Oil Co., Ltd.] 7 mass parts stearic acid [Asahi Denka Kogyo Co., Ltd.] 1 mass part vulcanization accelerator [ Noxeller DM, manufactured by Ouchi Shinsei Chemical Co., Ltd.] ・ ・ 1.3 parts by mass of zinc oxide [manufactured by Hakusui Chemical Co., Ltd.] ・ ・ ・ ・ ・ ・ ・ ・ 3 parts by mass of sulfur [Karuizawa Smelter] ........................... 0.5 parts by mass

<Preparation of Production Example 5 Adhesive Composition-1 and Coating Solution>
The adhesive composition kneaded by a conventional method according to the following composition was added to 1000 parts by mass of toluene (δ value: 18.2 MPa ^1/2 ), and dispersed or dissolved to prepare a coating solution.
(Adhesive composition)
Brominated butyl rubber [manufactured by JSR Corporation, Bromobutyl 2244] .... 90 parts by mass chlorosulfonated polyethylene [manufactured by DuPont Dow Elastomer Co., Ltd., Hyperon]
... 10 parts by mass carbon black [manufactured by Tokai Carbon Co., Ltd., Seast NB] ... 10 parts by mass phenol resin [manufactured by Sumitomo Bakelite Co., Ltd., PR-SC-400] 20 parts by mass stearic acid [New Nippon Rika Co., Ltd., 50S] ... 1 part by weight zinc oxide [Shiramizu Chemical Co., Ltd., Hakusuitec] ... 3 parts by weight P -Dinitrosobenzene [Ouchi Shinsei Chemical Co., Ltd., Balnock DNB]
... 3 parts by mass 1,4-phenylene dimaleimide [Ouchi Shinsei Chemical Co., Ltd., Barnock PM]
... 3 parts by mass vulcanization accelerator [Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller ZTC] ... 1 part by mass vulcanization accelerator [Ouchi Shinsei Chemical Industry Co., Ltd. Noxeller DM] ... 0.5 parts by mass vulcanization accelerator [Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller D] ... 1 part by mass sulfur [Tsurumi Chemical Co., Ltd., Jinhua Stamp fine powder sulfur] ... 1.5 parts by mass

<Preparation of Production Example 6 Adhesive Composition-2 and Coating Solution>
The adhesive composition kneaded by a conventional method according to the following composition was added to 1000 parts by mass of toluene (δ value: 18.2 MPa ^1/2 ), and dispersed or dissolved to prepare a coating solution.
(Adhesive composition)
Brominated butyl rubber [manufactured by JSR Corporation, Bromobutyl 2244] ..... 80 parts by mass chlorosulfonated polyethylene [manufactured by DuPont Dow Elastomer, Hypalon]
... 20 parts by mass carbon black [manufactured by Tokai Carbon Co., Ltd., Seast NB] ... 10 parts by mass phenol resin [manufactured by Sumitomo Bakelite Co., Ltd., PR-SC-400] 20 parts by mass stearic acid [New Nippon Rika Co., Ltd., 50S] ... 1 part by mass of zinc oxide [Shiramizu Chemical Industries, Hakusui Tech Co., Ltd.] ... 6 parts by weight P -Dinitrosobenzene [Ouchi Shinsei Chemical Co., Ltd., Balnock DNB]
... 6 parts by mass 1,4-phenylene dimaleimide [Ouchi Shinsei Chemical Co., Ltd., Balnock PM]
... 6 parts by mass vulcanization accelerator (Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller ZTC) ... 1 part by mass vulcanization accelerator (Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller DM) ... 0.5 parts by mass vulcanization accelerator [Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller D] ... 1 part by mass sulfur [Tsurumi Chemical Co., Ltd., Jinhua Stamp fine powder sulfur] ... 1.5 parts by mass

<Preparation of Production Example 7 Adhesive Composition-3 and Coating Solution>
The adhesive composition kneaded by a conventional method according to the following composition was added to 1000 parts by mass of toluene (δ value: 18.2 MPa ^1/2 ), and dispersed or dissolved to prepare a coating solution.
(Adhesive composition)
Brominated butyl rubber [manufactured by JSR Corporation, Bromobutyl 2244] ..... 70 parts by mass chlorosulfonated polyethylene [manufactured by DuPont Dow Elastomer, Hypalon]
... 30 parts by mass carbon black [manufactured by Tokai Carbon Co., Ltd., Seast NB] ... 10 parts by mass phenol resin [manufactured by Sumitomo Bakelite Co., Ltd., PR-SC-400] 20 parts by mass stearic acid [New Nippon Rika Co., Ltd., 50S] ... 1 part by mass of zinc oxide [Shiramizu Chemical Industries, Hakusui Tech Co., Ltd.] ... 6 parts by weight P -Dinitrosobenzene [Ouchi Shinsei Chemical Co., Ltd., Balnock DNB]
... 8 parts by mass 1,4-phenylene dimaleimide [Ouchi Shinsei Chemical Co., Ltd., Balnock PM]
・ ・ ・ 8 parts by mass vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd., Noxeller ZTC) ・ ・ ・ ・ 1 part by mass vulcanization accelerator [Ouchi Shinsei Chemical Co., Ltd., Noxeller DM] ... 0.5 parts by mass vulcanization accelerator [Ouchi Shinsei Chemical Industry Co., Ltd., Noxeller D] ... 1 part by mass sulfur [Tsurumi Chemical Co., Ltd., Jinhua Stamp fine powder sulfur] ... 1.5 parts by mass

<Example 1>
Using an electron beam irradiation apparatus “Production Curetron EBC200-100” manufactured by Nissin High Voltage Co., Ltd., the three-layer film (TPU / modified EVOH / TPU) obtained in Production Example 2 was irradiated with an acceleration voltage of 200 kV. The crosslinking treatment was performed by irradiating an electron beam under the condition of an amount of 60 kGy. After applying the coating liquid obtained in Production Example 5 to one side of the obtained multilayer thermoplastic resin film and drying it, the unvulcanized rubber-like elastic sheet having a thickness of 500 μm obtained in Production Example 3 is laminated. An inner liner was prepared. Using the inner liner, a pneumatic tire for a passenger car (195 / 65R15) was produced by the same production method as described above, except that a release agent was not used during vulcanization. And the oxygen permeation amount of the three-layer film, the elastic modulus, and the tire inner surface properties after vulcanization of the pneumatic tire were measured and evaluated by the following methods. The results are shown in Table 1.

(Oxygen transmission rate)
The prepared three-layer film was conditioned at 20 ° C. and 65% RH for 5 days. Using the two humidity-adjusted films obtained, using MOCON OX-TRAN 2/20 type manufactured by Modern Control Co., under 20 ° C. and 65% RH, in accordance with JIS K7126 (isobaric method) The amount of permeation was determined.

(Elastic modulus)
Using the autograph (AG-A500 type) manufactured by Shimadzu Corporation for the prepared three-layer film, the S-S curve at 23 ° C. and 150% RH under conditions of a distance between chucks of 50 mm and a tensile speed of 50 mm / min. Measurements were made. Then, the elastic modulus was obtained from the initial slope of the SS curve.

(Evaluation of tire inner surface properties)
About the pneumatic tire after performing vulcanization molding using a bladder, the appearance of the inner liner was visually observed, and the state of breakage of the film layer and the like were evaluated based on the following evaluation criteria.
A: Very good (no damage to the film layer with all 10 tires produced)
○: Good (only 1 out of 10 manufactured tires has a slight damage to the film layer, but there is no problem in terms of durability)
×: Defect (there is damage to the film layer)

<Example 2>
A pneumatic tire for a passenger car was produced and evaluated in the same manner as in Example 1 except that the irradiation amount of the electron beam to the three-layer film was changed to 100 kGy.

<Example 3>
A pneumatic tire for passenger cars was produced and evaluated in the same manner as in Example 1 except that the irradiation amount of the electron beam to the three-layer film was changed to 200 kGy.

<Example 4>
A pneumatic tire for passenger cars was produced and evaluated in the same manner as in Example 1 except that the irradiation amount of the electron beam to the three-layer film was changed to 500 kGy.

<Comparative Example 1>
A pneumatic tire for a passenger car (195) was used in the same manner as in Example 1 except that only the 500 μm-thick unvulcanized rubber-like elastic sheet obtained in Production Example 3 was used as an inner liner without using a three-layer film. / 65R15). And by the method similar to Example 1, the friction coefficient of the inner liner and the tire inner surface property after vulcanization of the pneumatic tire were measured and evaluated. The results are shown in Table 1.

<Comparative Example 2>
A pneumatic tire for passenger cars (195 / 65R15) was prepared in the same manner as in Comparative Example 1 except that a release agent (Mica powder manufactured by Matsumoto Yushi Seiyaku Co., Ltd. diluted to 50% by mass with water) was used during vulcanization. Produced. And by the method similar to Example 1, the friction coefficient of the inner liner and the tire inner surface property after vulcanization of the pneumatic tire were measured and evaluated. The results are shown in Table 1.

<Comparative Example 3>
A pneumatic tire for passenger cars was manufactured and evaluated in the same manner as in Example 1 except that the irradiation amount of the electron beam to the three-layer film was changed to 20 kGy.

  From Comparative Examples 1 and 2 in Table 1, it can be seen that in the conventional pneumatic tire, the inner liner is damaged unless a release agent is used during production. On the other hand, according to Examples 1 to 4 of Table 1 according to the present invention, it can be seen that the inner liner is not damaged even if a release agent is not used during production. Further, from Examples 1 to 4 and Comparative Example 3 in Table 1, it can be seen that the inner liner is damaged unless a release agent is used in a film having an electron beam irradiation amount of 20 kGy.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Bead part 3 Side wall part 4 Carcass 5 Belt 6 Inner liner 11 Upper mold 12 Unvulcanized tire 13 Lower mold 14 Bladder 15 Cylinder 16 Rod 17 Vulcanized tire

Claims (20)

The inner surface consists of a film layer irradiated with an electron beam at a dose of 50 to 600 kGy,
The film layer includes a resin film layer made of a resin film and an auxiliary layer made of an elastomer layer, and is located over the entire inner surface of the pneumatic tire as an inner liner,
Auxiliary layer, the thickness of the auxiliary layer in a portion corresponding to the radial width of at least 30mm in the region from the end of the tire belt to the bead portion is 0 than the thickness of the auxiliary layer in the portion corresponding to the lower portion of the belt A pneumatic tire characterized by being thicker than 2 mm.   The pneumatic tire according to claim 1, wherein the inner surface is made of a film layer having an elastic modulus of 20 to 1000 MPa.   The pneumatic tire according to claim 1, wherein the film layer does not contain a diene component.   The pneumatic tire according to claim 1, wherein the pneumatic tire is manufactured by a manufacturing method including a step of pressing an unvulcanized tire against a mold with a bladder without using a release agent. The pneumatic tire according to any one of the above.   The pneumatic tire according to claim 1, wherein the film layer includes a single-layer or multilayer thermoplastic resin film layer. The oxygen permeation amount at 20 ° C. and 65% RH of the film layer is 3.0 × 10 ⁻¹² cm ³ · cm ² · sec · cmHg or less. The pneumatic tire according to Crab. From the modified ethylene-vinyl alcohol copolymer obtained by reacting 1-50 parts by mass of an epoxy compound with respect to 100 parts by mass of an ethylene-vinyl alcohol copolymer having an ethylene content of 25-50 mol%. The pneumatic tire according to any one of claims 1 to 6 , comprising a layer. The film layer comprises a modified ethylene-vinyl alcohol copolymer obtained by reacting 1-50 parts by mass of an epoxy compound with 100 parts by mass of an ethylene-vinyl alcohol copolymer having an ethylene content of 25-50 mol%. Including a layer made of a resin composition in which a flexible resin or elastomer having a Young's modulus at 23 ° C. of 500 MPa or less is dispersed in a matrix,
The pneumatic tire according to any one of claims 1 to 6 , wherein the resin composition contains 10 to 80% by mass of the flexible resin or elastomer. Wherein the film layer is crosslinked, the pneumatic tire according to any one of claims 1-8. Wherein a surface of said film layer comprises a layer of a thermoplastic urethane-based elastomer, a pneumatic tire according to any one of claims 1-9. The pneumatic tire includes a laminate using the film layer and a rubber-like elastic layer adjacent to the film layer,
Wherein the rubbery elastomer layer, characterized by using butyl rubber or a halogenated butyl rubber, the pneumatic tire according to any one of claims 1-10. The pneumatic tire according to claim 11 , wherein the film layer and the rubber-like elastic body layer are bonded using an adhesive layer made of an adhesive composition. The adhesive composition contains a rubber component, and at least one of poly-p-dinitrosobenzene and 1,4-phenylene dimaleimide as a crosslinking agent and a crosslinking aid with respect to 100 parts by mass of the rubber component. The pneumatic tire according to claim 12 , which is a composition in which one kind is blended in an amount of 0.1 part by mass or more. The air according to claim 12 or 13 , wherein the adhesive composition is a composition containing a rubber component, and 10% by mass or more of the rubber component is composed of chlorosulfonated polyethylene. Enter tire. The adhesive composition according to any one of claims 12 to 14 , wherein the adhesive composition is a composition containing a rubber component and blending 2 to 50 parts by mass of a filler with respect to 100 parts by mass of the rubber component. The pneumatic tire according to Crab. The pneumatic tire according to claim 15 , wherein the filler is carbon black. The adhesive composition according to any one of claims 12 to 16 , wherein the adhesive composition comprises a rubber component, and 50% by mass or more of the rubber component is a composition comprising butyl rubber and / or halogenated butyl rubber. Pneumatic tire described in 2. Wherein the adhesive composition comprises a rubber component, and characterized in that it is a composition containing 0.1 part by mass or more vulcanization accelerator per 100 parts by mass of the rubber component, claims 12 to The pneumatic tire according to any one of 17 . Installing an unvulcanized tire having a film layer irradiated with an electron beam at an irradiation amount of 50 to 600 kGy disposed on the inner surface in a mold;
Installing a bladder inside the unvulcanized tire;
Inflating the bladder, pressing the unvulcanized tire against a mold through the film layer, and vulcanizing the unvulcanized tire;
Including
The film layer includes a resin film layer made of a resin film and an auxiliary layer made of an elastomer layer, and is located as an inner liner over the entire inner surface of the pneumatic tire, and the auxiliary layer extends from the end of the tire belt to the bead portion. In this method, the thickness of the auxiliary layer corresponding to the radial width of at least 30 mm is 0.2 mm or more thicker than the thickness of the auxiliary layer corresponding to the lower part of the belt. And
A method, wherein no mold release agent is used in the vulcanization molding step. The method according to claim 19 , wherein the elastic modulus of the film layer is 20 to 1000 MPa.

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