JP6653624B2 - Method of manufacturing inner liner of pneumatic tire and method of manufacturing pneumatic tire - Google Patents

Description

  The present invention relates to a method for manufacturing an inner liner of a pneumatic tire and a method for manufacturing a pneumatic tire.

  Conventionally, a rubber composition mainly composed of butyl rubber, halogenated butyl rubber, or the like has been used for an inner liner provided as an air barrier layer on the inner surface of a tire to maintain the internal pressure of the tire. However, these butyl rubber-based rubber compositions have low gas barrier properties. Therefore, when such a rubber composition is used for an inner liner, the thickness of the inner liner needs to be about 1 mm. For this reason, the weight of the inner liner in the tire is, for example, about 5%, which is an obstacle to reducing the weight of the tire and improving the fuel efficiency of the vehicle.

  On the other hand, it is known that a thermoplastic resin such as an ethylene-vinyl alcohol copolymer (hereinafter may be simply abbreviated as “EVOH”) has better gas barrier properties than rubber. For example, since EVOH has an air permeation of 1/100 or less of the rubber composition for a butyl-based inner liner, even at a thickness of 100 μm or less, the internal pressure retention of the tire can be improved. Therefore, when EVOH is used as the inner liner, it can be used even with a thickness of 100 μm or less, so that the weight of the tire can be reduced. Furthermore, when EVOH is used as the inner liner, it is hard to break due to bending deformation during rolling of the tire, and hardly causes cracks. Therefore, it can be said that the use of a thermoplastic resin such as EVOH for the inner liner of the tire is effective in improving the internal pressure retention of the pneumatic tire.

  However, since a thermoplastic resin such as EVOH has poor adhesion to a rubber member used for a tire, a layer made of a thermoplastic elastomer is provided as an adhesive layer on a layer made of the thermoplastic resin. Adding an epoxy group, a maleic anhydride group, an amino group, a carboxylic acid group, a silicon-containing functional group, or the like to an elastomer (see Patent Documents 1 to 3), or adding a layer made of a thermoplastic resin or a film layer containing the same. It has been practiced to provide a layer made of epoxidized natural rubber (ENR) as an adhesive layer.

JP 2013-57016 A JP 2013-10493 A International Publication No. 2012/164918

As described above, a layer made of a thermoplastic elastomer is provided as an adhesive layer on a layer made of a thermoplastic resin, and the thermoplastic elastomer further contains an epoxy group, a maleic anhydride group, an amino group, a carboxylic acid group, By adding a silicon functional group or the like, the peeling of the layer made of the thermoplastic resin from the rubber member can be suppressed, but there is still room for improvement in the adhesive force between the layer made of the thermoplastic resin and the adhesive layer. In particular, there has been a problem that a layer made of a thermoplastic resin is peeled off from the adhesive layer when molding or vulcanizing a green tire, thereby increasing a defective rate at the time of production.
In addition, when a layer made of epoxidized natural rubber (ENR) is provided as an adhesive layer on one or both sides of a layer made of a thermoplastic resin or a film layer containing the same, the adhesive layer has too high tackiness, In the green tire molding process, there were manufacturing problems such as an adhesive layer sticking to a worker or a molding drum of the green tire.

Then, an object of the present invention is to solve the above-mentioned problem of the prior art, and to provide a method of manufacturing an inner liner of a pneumatic tire in which adhesion between adjacent rubber members is high and delamination hardly occurs.
Another object of the present invention is to provide a method of manufacturing a pneumatic tire having high adhesion between an inner liner and an adjacent rubber member, using the inner liner manufactured by the method of manufacturing an inner liner. And

  The gist configuration of the present invention for solving the above problems is as follows.

The method for producing an inner liner of a pneumatic tire according to the present invention is a method for producing an inner liner of a pneumatic tire comprising a film layer and an adhesive layer provided on at least one surface of the film layer. ,
The film layer has a gas barrier layer and an elastic layer disposed on at least one surface of the gas barrier layer,
The gas barrier layer contains at least a thermoplastic resin,
The elastic layer contains at least a polyurethane-based thermoplastic elastomer,
The adhesive layer contains at least a polystyrene-based thermoplastic elastomer,
After laminating the film layer and the adhesive layer by co-extrusion, an active energy ray is irradiated.
The inner liner of a pneumatic tire manufactured by the method for manufacturing an inner liner of a pneumatic tire of the present invention has high adhesiveness between adjacent rubber members and is less likely to cause delamination.

  In a preferred example of the method of manufacturing an inner liner for a pneumatic tire according to the present invention, the adhesive layers are provided on both surfaces of the film layer. In this case, on the inner surface of the tire, when the inner liner is extended in the tire circumferential direction and the ends of the inner liner in the tire circumferential direction are overlapped and arranged, the adhesive layers at the ends come into contact with each other, and the adhesive layer Since the adhesive strength between them is higher than the adhesive strength between the film layer and the adhesive layer, peeling between the ends of the inner liner in the tire circumferential direction can be suppressed.

In another preferred embodiment of the method of manufacturing the inner liner of the pneumatic tire of the present invention, the adhesive layer further contains a thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer,
The mass ratio of the polystyrene-based thermoplastic elastomer contained in the adhesive layer to the thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer is in the range of 25:75 to 75:25.
In this case, the adhesiveness between the film layer and the adhesive layer is further improved.

In another preferred embodiment of the method for producing an inner liner of a pneumatic tire according to the present invention, the styrene content of the polystyrene-based thermoplastic elastomer contained in the adhesive layer is 40% by mass to 55% by mass.
In this case, the adhesiveness with the rubber member is further improved, and when incorporated into a green tire, the flowability of the adhesive layer in vulcanization of the green tire can be suppressed, and workability can be improved. In this case, the destruction of the adhesive layer can be further suppressed even in a low-temperature environment or during running.

  In another preferred embodiment of the method for manufacturing an inner liner of a pneumatic tire according to the present invention, the film layer is formed by alternately stacking the gas barrier layer and the elastic layer, and the elastic layer is formed of the film layer. Located on both outermost surfaces. In this case, the adhesive force between the film layer and the adhesive layer of the inner liner is further improved.

  In another preferred embodiment of the method for manufacturing an inner liner for a pneumatic tire according to the present invention, the film layer has a total number of seven or more layers of the gas barrier layer and the elastic layer. In this case, the gas barrier properties, crack resistance, and workability of the inner liner are improved.

  In the method for manufacturing an inner liner of a pneumatic tire according to the present invention, it is preferable that a rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm is laminated on at least one surface of the inner liner. In this case, generation of cracks in the inner liner can be suppressed.

Further, a method of manufacturing a pneumatic tire according to the present invention is characterized by using the inner liner of a pneumatic tire manufactured by the above-described method of manufacturing an inner liner of a pneumatic tire.
The pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to the present invention has high adhesiveness between the inner liner and the adjacent rubber member.

In a preferred example of the manufacturing method of the pneumatic tire of the present invention,
On the tire inner surface, the inner liner extends in the tire circumferential direction, and the ends of the inner liner in the tire circumferential direction are arranged so as to overlap in the tire radial direction,
Both ends of the inner liner in the tire circumferential direction are parallel to the tire width direction,
The overlap width between the ends of the inner liner in the tire circumferential direction is in the range of 5 mm to 20 mm.
In this case, the adhesiveness between the inner liner and the adjacent rubber member is even higher.

In another preferred embodiment of the method for manufacturing a pneumatic tire of the present invention,
On the tire inner surface, the inner liner extends in the tire circumferential direction, and the ends of the inner liner in the tire circumferential direction are arranged so as to overlap in the tire radial direction,
The end of the inner liner has peaks and valleys alternately,
The end of the inner liner, the angle of the peak of the peak, the angle of the bottom of the valley, the range of 45 ° ~ 120 °,
The overlapping width between the ends of the inner liner in the tire circumferential direction is in the range of 1 mm to 13 mm.
Also in this case, the adhesiveness between the inner liner and the adjacent rubber member is even higher.

In another preferred embodiment of the method for manufacturing a pneumatic tire according to the present invention, the pneumatic tire includes a rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm on a radially outer side of the inner liner. Equipped. In this case, it is possible to improve the peeling resistance between the ends of the inner liner while suppressing the occurrence of cracks in the inner liner.
Here, it is more preferable that the thickness of the rubber-like elastic layer is 0.2 mm to 0.6 mm. In this case, it is possible to further improve the peeling resistance between the ends of the inner liner while further suppressing the occurrence of cracks in the inner liner.

In another preferred embodiment of the pneumatic tire manufacturing method of the present invention, another tire member is laminated on the pneumatic tire inner liner manufactured by the above-described pneumatic tire inner liner manufacturing method. And forming a green tire,
Vulcanizing the green tire,
including. Here, in the preferred example, a green tire may be formed by laminating another tire member on the above-described inner liner laminated with a rubber-like elastic layer.
In this case, a pneumatic tire having high adhesiveness between the inner liner and the adjacent rubber member can be manufactured.

According to the present invention, it is possible to provide a method for producing an inner liner of a pneumatic tire, which has high adhesiveness between adjacent rubber members and is less likely to cause delamination.
Further, according to the present invention, it is possible to provide a method for manufacturing a pneumatic tire having high adhesiveness between an inner liner and an adjacent rubber member.

1 is a partial cross-sectional view of an example of an inner liner of a pneumatic tire manufactured by a method of manufacturing an inner liner of a pneumatic tire according to the present invention. FIG. 1 is a partial cross-sectional view of an example of a pneumatic tire manufactured by a method for manufacturing a pneumatic tire according to the present invention. FIG. 3 is a partial cross-sectional view of an example of a pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to the present invention, which is viewed from the inner surface of the tire and at a joining portion of an inner liner end. FIG. 2 is a partial cross-sectional view of an example of a pneumatic tire manufactured by the method of manufacturing a pneumatic tire according to the present invention, which is viewed from the tire width direction and at a joint portion of an inner liner end. FIG. 5 is a partial cross-sectional view of another example of a pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to the present invention, showing a joint portion at an end of an inner liner, as viewed from a tire width direction.

<Method of manufacturing inner liner for pneumatic tire>
Hereinafter, a method for manufacturing an inner liner of a pneumatic tire of the present invention will be described in detail by way of example based on the embodiment.
FIG. 1 is a partial cross-sectional view of an example of an inner liner of a pneumatic tire manufactured by the method for manufacturing an inner liner of a pneumatic tire of the present invention. The inner liner 100 shown in FIG. 1 includes a film layer 10 and adhesive layers 20 provided on both sides of the film layer 10.
In the inner liner 100 shown in FIG. 1, the adhesive layers 20 are provided on both surfaces of the film layer 10, but in the inner liner of the pneumatic tire of the present invention, only one surface of the film layer has the adhesive layer. May be provided.

  In an inner liner of a pneumatic tire manufactured by the method of manufacturing an inner liner of a pneumatic tire of the present invention (hereinafter, may be simply abbreviated as “inner liner”), as in an inner liner 100 shown in FIG. It is preferable that the adhesive layers 20 are provided on both sides of the film layer 10. At this time, a rubber-like elastic layer may be laminated on one surface of the film layer 10. When the adhesive layer is disposed on both surfaces of the film layer, or when the adhesive layer is disposed on one surface of the film layer and the rubber-like elastic material layer is laminated on the other surface of the film layer On the inner surface of the tire, the inner liner extends in the tire circumferential direction, and when the ends of the inner liner in the tire circumferential direction are overlapped with each other in the tire radial direction, the adhesive layers at the ends come into contact with each other, Alternatively, the adhesive layer at the end is bonded to the rubber-like elastic material layer at the other end, so that peeling between the ends of the inner liner in the tire circumferential direction can be suppressed. The adhesive layer of the inner liner manufactured by the method of the present invention does not have too high tackiness. Therefore, even if the adhesive layer is provided on both surfaces of the film layer, the forming drum is not formed in the green tire forming step. Adhesion of the adhesive layer to the substrate is suppressed, and workability can be improved.

The film layer 10 of the inner liner 100 shown in FIG. 1 has a gas barrier layer 11 and elastic layers 12 provided on both surfaces of the gas barrier layer 11, and the gas barrier layer 11 and the elastic layer 12 are alternately arranged. Are laminated.
In the film layer 10 in FIG. 1, the elastic layers 12 are provided on both surfaces of the gas barrier layer 11, but the film layer of the inner liner manufactured by the method of the present invention is provided only on one surface of the gas barrier layer. An elastic layer may be provided. When the film layer has the gas barrier layer and the elastic layer, cracks can be suppressed from entering the gas barrier layer, and the crack resistance of the inner liner is improved.

In the inner liner manufactured by the method of the present invention, it is preferable that the elastic layer 12 is provided on both surfaces of the gas barrier layer 11 as in the inner liner 100 shown in FIG. When the elastic layer is provided on both surfaces of the gas barrier layer, cracks in the gas barrier layer are further suppressed, and the crack resistance of the inner liner is further improved.
In addition, the film layer of the inner liner of the pneumatic tire manufactured by the method of manufacturing the inner liner of the pneumatic tire of the present invention may have another layer in addition to the gas barrier layer and the elastic layer.

  In the inner liner manufactured by the method of the present invention, the gas barrier layer contains at least a thermoplastic resin, and may contain other components in addition to the thermoplastic resin, or may be made of only the thermoplastic resin. . Here, as another component, a flexible resin having a dynamic storage elastic modulus E ′ at −20 ° C. lower than that of the thermoplastic resin is preferable.

  The thermoplastic resin used for the gas barrier layer is not particularly limited, and includes ethylene-vinyl alcohol copolymer resin, polyamide resin, polyvinylidene chloride resin, polyester resin, and the like. And ethylene-vinyl alcohol copolymer resin. Such an ethylene-vinyl alcohol copolymer resin has a low oxygen permeation amount and a very good gas barrier property. These thermoplastic resins may be used alone or in a combination of two or more.

  Examples of the ethylene-vinyl alcohol copolymer resin include, in addition to the ethylene-vinyl alcohol copolymer, a modified ethylene-vinyl alcohol copolymer obtained by reacting the ethylene-vinyl alcohol copolymer with, for example, an epoxy compound. And the like. Such a modified ethylene-vinyl alcohol copolymer has a lower modulus of elasticity than a normal ethylene-vinyl alcohol copolymer, so that it has high resistance to rupture when flexing and excellent crack resistance in a low-temperature environment. .

The ethylene-vinyl alcohol copolymer preferably has an ethylene content of 25 mol% to 50 mol%, more preferably 30 mol% to 48 mol%, and more preferably 35 mol% to 45 mol%. Is even more preferred. If the ethylene content is 25 mol% or more, the bending resistance, fatigue resistance and melt moldability are good, and if it is 50 mol% or less, the gas barrier properties are sufficiently high.
The ethylene-vinyl alcohol copolymer has a saponification degree (that is, a ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in the ethylene-vinyl alcohol copolymer) of 80 mol% or more. Is preferably 95 mol% or more, more preferably 99 mol% or more. When the saponification degree is 80 mol% or more, the gas barrier properties and the thermal stability during molding are sufficiently high.
Further, the ethylene-vinyl alcohol copolymer has a melt flow rate (MFR) of 190 g / min at a load of 2160 g / 0.1 g / 10 min to 30 g / g from a viewpoint of obtaining gas barrier properties, flex resistance and fatigue resistance. It is preferably 10 minutes, more preferably 0.3 g / 10 min to 25 g / 10 min, and even more preferably 0.5 g / 10 min to 20 g / 10 min.

  The method for producing the modified ethylene-vinyl alcohol copolymer is not particularly limited, but a method in which the ethylene-vinyl alcohol copolymer is reacted with an epoxy compound in a solution is preferably used. More specifically, a modified ethylene-vinyl alcohol copolymer is produced by adding and reacting an epoxy compound to a solution of the ethylene-vinyl alcohol copolymer in the presence of an acid catalyst or an alkali catalyst, preferably in the presence of an acid catalyst. can do. Examples of the reaction solvent include aprotic polar solvents such as dimethylsulfoxide, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Examples of the acid catalyst include p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, sulfuric acid, and boron trifluoride, and examples of the alkaline catalyst include sodium hydroxide, potassium hydroxide, and lithium hydroxide. And sodium methoxide. The amount of the catalyst is preferably in the range of 0.0001 to 10 parts by mass based on 100 parts by mass of the ethylene-vinyl alcohol copolymer.

  The epoxy compound reacted with the ethylene-vinyl alcohol copolymer is preferably a monovalent epoxy compound. The divalent or higher epoxy compound may cause a cross-linking reaction with the ethylene-vinyl alcohol copolymer to generate a gel, butter, and the like, thereby deteriorating the quality of the inner liner. Glycidol and epoxypropane are particularly preferable among monovalent epoxy compounds from the viewpoint of ease of production, gas barrier properties, flex resistance and fatigue resistance of the modified ethylene-vinyl alcohol copolymer. In addition, the epoxy compound is preferably reacted in an amount of 1 to 50 parts by mass, more preferably 2 to 40 parts by mass, and more preferably 5 to 50 parts by mass, based on 100 parts by mass of the ethylene-vinyl alcohol copolymer. It is even more preferred to react from 35 parts by mass to 35 parts by mass.

  The modified ethylene-vinyl alcohol copolymer has a melt flow rate (MFR) of 190 g at a load of 2160 g and a load of 0.1 g / 10 min to 30 g / 10 from the viewpoint of obtaining gas barrier properties, flex resistance and fatigue resistance. Min, more preferably 0.3 g / 10 min to 25 g / 10 min, even more preferably 0.5 g / 10 min to 20 g / 10 min.

On the other hand, the flexible resin has a dynamic storage modulus E ′ at −20 ° C. lower than that of the thermoplastic resin, and preferably 6 × 10 ⁸ Pa or less. By using a flexible resin having a dynamic storage elastic modulus E ′ at −20 ° C. of 6 × 10 ⁸ Pa or less, the elastic modulus of the gas barrier layer is reduced, and the crack resistance and bending resistance in a low-temperature environment are improved. Can be.

  The flexible resin preferably has a functional group that reacts with a hydroxyl group. When the flexible resin has a functional group that reacts with a hydroxyl group, the flexible resin is uniformly dispersed in the thermoplastic resin. 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 a maleic anhydride-modified hydrogenated styrene-ethylene-butadiene-styrene block copolymer, a maleic anhydride-modified ultra-low-density polyethylene, and the like.

  Further, the flexible resin preferably has an average particle size of 5 μm or less. When the average particle size of the flexible resin is 5 μm or less, the bending resistance of the gas barrier layer can be sufficiently improved, and the internal pressure retention of the tire can be sufficiently improved. The average particle size of the flexible resin in the gas barrier layer can be observed by a transmission electron microscope (TEM) by, for example, freezing a sample, cutting the sample into sections using a microtome.

  The content of the flexible resin in the gas barrier layer is preferably in a range of 10% by mass to 80% by mass, and more preferably in a range of 10% by mass to 30% by mass. If the content of the flexible resin is 10% by mass or more, the effect of improving the bending resistance is large, and if it is 80% by mass or less, the gas permeability is sufficiently low.

  The resin composition used for the gas barrier layer may be any one of various types such as a heat stabilizer, an ultraviolet absorber, an antioxidant, a colorant, and a filler in addition to the thermoplastic resin and the flexible resin as long as the object of the present invention is not impaired. May be included. When the resin composition used for the gas barrier layer contains these additives, the amount is preferably 50% by mass or less, more preferably 30% by mass or less, and preferably 10% by mass or less based on the total amount of the resin composition. % Is particularly preferable.

Further, the gas barrier layer preferably has an air permeability at 20 ° C. and 65% RH of 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less, preferably 1.0 × 10 2 More preferably, it is not more than ⁻¹² cm ³ · cm / cm ² · sec · cmHg. The air permeability is measured according to JIS K7126-1: 2006 (isobaric method). When the air permeability at 20 ° C. and 65% RH is 3.0 × 10 ⁻¹² cm ³ · cm / cm ² · sec · cmHg or less, even if the gas barrier layer is thinned, the internal pressure holding characteristics of the tire are high. Thus, the weight of the tire can be sufficiently reduced.

  The gas barrier layer preferably has an average thickness of 0.001 μm to 10 μm. If the average thickness of one layer of the gas barrier layer is within this range, the number of layers constituting the inner liner can be increased, and the inner liner has the same overall thickness but a smaller number of layers. Can improve gas barrier properties and crack resistance.

  On the other hand, the elastic layer 12 contains at least a polyurethane-based thermoplastic elastomer. When the elastic layer contains a polyurethane-based thermoplastic elastomer, cracks are less likely to enter the gas barrier layer, and the crack resistance of the inner liner is further improved.

  The elastic layer contains at least a polyurethane-based thermoplastic elastomer, but may contain other components in addition to the polyurethane-based thermoplastic elastomer, or may be composed of only the polyurethane-based thermoplastic elastomer. Here, as other components, a thermoplastic elastomer (TPE) other than the polyurethane-based thermoplastic elastomer, a soft material having a Young's modulus at 23 ° C. lower than that of the polyurethane-based thermoplastic elastomer, and the like can be mentioned.

  In the inner liner manufactured by the method of the present invention, like the inner liner 100 shown in FIG. 1, the film layer 10 is formed by alternately laminating the gas barrier layers 11 and the elastic layers 12, and the elastic layer 12 is formed of a film. Preferably, it is located on both outermost surfaces of layer 10. Although not shown, it is also preferable that the gas barrier layer is located on both outermost surfaces of the film layer. In this case, since the material of the gas barrier layer 11 or the elastic layer 12 is closer to that of the adhesive layer 20 than that of the conventional adhesive made of diene rubber, the adhesive layer 20 and the film layer 10 (that is, the outermost surface) are used. The adhesive strength of the layer to the gas barrier layer 11 or the elastic layer 12) is large, and it is difficult to peel off.

  The polyurethane-based thermoplastic elastomer (TPU) used for the elastic layer includes (1) a polyurethane obtained by reacting a short-chain glycol and an isocyanate as a hard segment, and (2) a reaction of a long-chain glycol and an isocyanate as a soft segment. And a linear multi-block copolymer comprising the obtained polyurethane. Here, polyurethane is a general term for compounds having a urethane bond (-NHCOO-) obtained by a polyaddition reaction (urethane-forming reaction) between isocyanate (-NCO) and alcohol (-OH). In the inner liner manufactured by the method of the present invention, since the elastic layer contains TPU, the stretchability and thermoformability can be improved by laminating the elastic layer. In addition, in such an inner liner, since the interlayer adhesion between the elastic layer and the gas barrier layer is improved, durability such as crack resistance is high, and even when the inner liner is deformed and used, gas barrier properties and stretchability are maintained. can do.

  The TPU is composed of a polymer polyol, an organic polyisocyanate, a chain extender and the like. The polymer polyol is a substance having a plurality of hydroxyl groups and is obtained by polycondensation, addition polymerization (for example, ring-opening polymerization), polyaddition, or the like. Examples of the polymer polyol include polyester polyol, polyether polyol, polycarbonate polyol, and co-condensates thereof (for example, polyester-ether-polyol). Among these, a polyester polyol or a polycarbonate polyol is preferred, and a polyester polyol is particularly preferred. These polymer polyols may be used alone or in combination of two or more.

  Here, the polyester polyol is, for example, directly condensed with a compound capable of forming an ester, such as a dicarboxylic acid, an ester thereof, and an anhydride thereof, and a low-molecular polyol by an esterification reaction or a transesterification reaction according to a conventional method. Or by subjecting a lactone to ring-opening polymerization.

  The dicarboxylic acid that can be used for producing the polyester polyol is not particularly limited, and includes dicarboxylic acids generally used in the production of polyester. Specific examples of the dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecandioic acid, methyl succinic acid, 2-methylglutaric acid, trimethyladipic acid, Aliphatic dicarboxylic acids having 4 to 12 carbon atoms such as methyloctane diacid, 3,8-dimethyldecanedioic acid and 3,7-dimethyldecane diacid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; terephthalic acid, isophthalic acid Examples thereof include acids, aromatic dicarboxylic acids such as orthophthalic acid and naphthalenedicarboxylic acid. These dicarboxylic acids may be used alone or in combination of two or more. Among these, an aliphatic dicarboxylic acid having 6 to 12 carbon atoms is preferable, and adipic acid, azelaic acid or sebacic acid is particularly preferable. These dicarboxylic acids have a carbonyl group that reacts more easily with a hydroxyl group, and can greatly improve the interlayer adhesion with the gas barrier layer.

  The low molecular polyol that can be used for producing the polyester polyol is not particularly limited, and includes a low molecular polyol generally used in the production of polyester. Specific examples of the low-molecular polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butylene glycol, 4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octane Diol, 2,7-dimethyl-1,8-octanediol, 1,9-nonanediol, 2-methyl-1,9-nonanediol, 2,8-dimethyl-1,9-nonanediol, 1,10- Aliphatic diols having 2 to 15 carbon atoms such as decanediol and 2,2-diethyl-1,3-propanediol Alicyclic diols such as 1,4-cyclohexanediol, cyclohexanedimethanol, cyclooctanedimethanol, dimethylcyclooctanedimethanol; aromatic dihydric alcohols such as 1,4-bis (β-hydroxyethoxy) benzene; No. These low molecular polyols may be used alone or as a mixture of two or more. Among them, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 1,9-nonanediol, 2,8- Aliphatic diols having 5 to 12 carbon atoms and having a methyl group in the side chain, such as dimethyl-1,9-nonanediol, are preferred. The polyester polyol obtained by using such an aliphatic diol easily reacts with a hydroxyl group, and can greatly improve interlayer adhesion with a gas barrier layer. Further, a small amount of a trifunctional or higher functional low molecular polyol can be used in combination with the low molecular polyol. Examples of the trifunctional or higher functional low molecular polyol include trimethylolpropane, trimethylolethane, glycerin, and 1,2,6-hexanetriol.

  Examples of the lactone that can be used for producing the polyester polyol include ε-caprolactone and β-methyl-δ-valerolactone.

  Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (methyltetramethylene) glycol, and the like. These polyether polyols may be used alone or in a combination of two or more. Among these, polytetramethylene glycol is preferred.

  Examples of the polycarbonate polyol include C2-C12 fats such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, and 1,10-decanediol. Compounds obtained by condensation polymerization of an aromatic diol or a mixture thereof by the action of diphenyl carbonate or phosgene are preferred.

  The high molecular polyol has a number average molecular weight of preferably 500 or more, more preferably 600 or more, still more preferably 700 or more, and preferably 8,000 or less, and more preferably 5 or less. It is more preferably 3,000 or less, and even more preferably 3,000 or less. When the number average molecular weight of the high molecular polyol is 500 or more, the elasticity of the obtained TPU is high, and the mechanical properties such as the stretchability of the inner liner and the thermoformability are good. On the other hand, if the number average molecular weight of the high molecular polyol is 8,000 or less, the compatibility with the organic polyisocyanate is high, the mixing in the polymerization process is easy, and a uniform TPU can be obtained. In addition, the number average molecular weight of the high molecular polyol is a number average molecular weight measured based on JIS K 1577 and calculated based on a hydroxyl value.

  The organic polyisocyanate is not particularly limited, and a known organic polyisocyanate generally used in the production of TPU, for example, an organic diisocyanate can be used. Examples of the organic diisocyanate include 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate, and toluene. Aromatic diisocyanates such as diisocyanate; aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate. Among these, 4,4'-diphenylmethane diisocyanate is preferred from the viewpoint of improving the strength and flex resistance of the obtained inner liner. These organic polyisocyanates may be used alone or in a combination of two or more.

  The chain extender is not particularly limited, and a known chain extender generally used in the production of TPU can be used, and has a molecular weight of 300 or more having two or more active hydrogen atoms capable of reacting with an isocyanate group in a molecule. The following low molecular weight compounds are preferably used. Examples of the chain extender include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-cyclohexanediol, and the like. . Among these, 1,4-butanediol is particularly preferred from the viewpoint of further improving the stretchability and thermoformability of the obtained inner liner. These chain extenders may be used alone or in a combination of two or more.

  Examples of the method for producing the TPU include a production method using a polymer polyol, an organic polyisocyanate and a chain extender and utilizing a known urethanation reaction technique, and using either a prepolymer method or a one-shot method. Is also good. In particular, it is preferable to carry out melt polymerization substantially in the absence of a solvent, and it is more preferable to carry out continuous melt polymerization using a multi-screw extruder.

  In the TPU, the ratio of the mass of the organic polyisocyanate to the total mass of the polymer polyol and the chain extender [organic polyisocyanate / (polymer polyol + chain extender)] is preferably 1.02 or less. When the ratio is 1.02 or less, long-term operation stability during molding is also good.

  Examples of the thermoplastic elastomer (TPE) other than the above-mentioned polyurethane-based thermoplastic elastomer include, for example, a polystyrene-based thermoplastic elastomer, a polyolefin-based thermoplastic elastomer, a polydiene-based thermoplastic elastomer, a polyvinyl chloride-based thermoplastic elastomer, and a chlorinated thermoplastic elastomer. Polyethylene-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, fluororesin-based thermoplastic elastomers, and the like, and these thermoplastic elastomers may be used alone or in combination of two or more. May be used.

  On the other hand, the soft material has a Young's modulus at 23 ° C. lower than that of the polyurethane-based thermoplastic elastomer, preferably 1000 MPa or less, more preferably 0.01 MPa to 500 MPa. Crack resistance is improved by using a soft material having a Young's modulus at 23 ° C. of 1000 MPa or less.

  The soft material is preferably a compound having a functional group capable of reacting with a hydroxyl group. When the soft material has a functional group capable of reacting with a hydroxyl group, the soft material can be uniformly dispersed in the polyurethane-based thermoplastic elastomer, and the average particle size of the soft material can be reduced. Here, the functional group capable of reacting with a hydroxyl group includes a hydroxyl group, a carboxyl group, a carboxylate group, an isocyanate group, an isothiocyanate group, an epoxy group, an amino group, a boron-containing group, maleic acid, maleic anhydride and alkoxysilane. And a functional group introduced by modification with a compound selected from the group consisting of: Here, the functional group is not limited to those capable of directly reacting with the polyurethane-based thermoplastic elastomer molecule, or those having a high affinity. By preliminarily reacting with another agent, the functional group can react with the polyurethane-based thermoplastic elastomer molecule. Examples are also included. The soft material may have two or more of such functional groups.

  The soft material is preferably a compound having a molecular weight of 10,000 or less, more preferably a compound having a molecular weight of 5,000 or less, still more preferably a compound having a molecular weight of 2,000 or less, and particularly preferably. It is a compound having a molecular weight of 1,000 or less. If the molecular weight of the soft material is within the above range, the soft material will be uniformly dispersed in the polyurethane-based thermoplastic elastomer, and the film forming property of the composition containing the polyurethane-based thermoplastic elastomer and the soft material will be improved. It can also be done. Further, from the viewpoint of strengthening entanglement with the polyurethane-based thermoplastic elastomer and improving crack resistance, the molecular weight of the soft material is preferably 750 or more. When the soft material is a polymer, the molecular weight of the soft material refers to a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

  The soft materials include butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), natural rubber (NR), butyl rubber (IIR), and isobutylene, particularly from the viewpoint of improving crack resistance. -P-methylstyrene, chlorosulfonated polyethylene rubber (CSM), ethylene-propylene rubber (EPM, EPDM), ethylene-butene rubber, ethylene-octene rubber, chloroprene rubber (CR), acrylic rubber (ACM), nitrile rubber (NBR) , Silicone rubber, and the like, as well as hydrogenated rubber (eg, hydrogenated SBR), modified rubber [eg, modified natural rubber, brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), and bromine. Isobutylene-p-methylstyrene, etc.], liquid rubber (ie, low molecular weight Beam), or the like can be used. From the same viewpoint, the soft materials include polyethylene (PE), polypropylene (PP), ethylene-butene copolymer, styrene-ethylene-butene-styrene block copolymer (SEBS), and styrene-ethylene-propylene. -Styrene block copolymer (SEPS), styrene-isobutylene-chloromethylstyrene block copolymer, polyamide, and other polymers, as well as hydrogenated and modified products thereof can be used. More specifically, a maleic anhydride-modified hydrogenated styrene-ethylene-butadiene-styrene block copolymer, a maleic anhydride-modified ultra-low density polyethylene and the like can be mentioned. These soft materials may be used alone or in a combination of two or more.

  In addition, a known plasticizer may be used as the soft material from the viewpoint of excellent compatibility with the polyurethane-based thermoplastic elastomer and lowering the glass transition point (Tg). Here, phthalic acid-based plasticizers such as dibutyl phthalate, diheptyl phthalate, dioctyl phthalate (DOP), ditridecyl phthalate, and trioctyl phthalate; and phosphate-based plasticizers such as tricresyl phosphate and trioctyl phosphate are used as the plasticizer. Fatty acid-based plasticizers such as tributyl citrate, dioctyl adipate, dioctyl sebacate, and methyl acetyl ricinoleate; epoxy-based plasticizers such as epoxidized soybean oil, diisodecyl-4,5-epoxytetrahydrophthalate; N-butylbenzene sulfone In addition to amide plasticizers such as amides, chlorinated paraffins and sunflower oil suitable for diene elastomers can be mentioned. These soft materials may be used alone or in a combination of two or more.

  The content of the soft material in the elastic layer is preferably 10% by mass to 30% by mass. When the content of the soft material is 10% by mass or more, crack resistance can be sufficiently improved, and the low-temperature hardness of the elastic layer can be sufficiently reduced. Further, when the content of the soft material is 30% by mass or less, the film formability can be sufficiently improved.

  In the composition used for the elastic layer, the above-mentioned polyurethane-based thermoplastic elastomer, a thermoplastic elastomer other than the polyurethane-based thermoplastic elastomer, in addition to a soft material, a heat stabilizer, an ultraviolet absorber, an antioxidant, a coloring agent, Additives such as fillers can be appropriately selected and included within a range that does not impair the purpose of the present invention. The content of these additives in the composition used for the elastic layer is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less.

The elastic layer preferably has an air permeability at 20 ° C. and 65% RH of 3.0 × 10 ⁻⁸ cm ³ · cm / cm ² · sec · cmHg or less. The air permeability is measured according to JIS K7126-1: 2006 (isobaric method).

  The elastic layer preferably has an average thickness of 0.001 μm to 40 μm. By setting the average thickness of one layer of the elastic layer in the above range, the number of layers constituting the inner liner can be increased, and the inner thickness is the same as that of the inner liner having the same thickness but a smaller number of layers. The gas barrier properties and crack resistance of the liner can be improved.

  As for the average thickness of one elastic layer, the ratio of the average thickness of one elastic layer to the average thickness of one gas barrier layer (elastic layer / gas barrier layer) is 2/1 (= 2) or more. And more preferably 3/1 (= 3) or more. By setting the thickness ratio between the gas barrier layer and the elastic layer in this manner, the bending fatigue characteristics of the film layer until the entire layer is broken is improved.

In the film layer of the inner liner manufactured by the method of the present invention, the total number of the gas barrier layer and the elastic layer is preferably 7 or more. With such a film layer, defects such as pinholes and cracks generated in a certain layer can be suppressed from progressing to an adjacent layer, so that cracks and breaks over the entire film layer can be prevented, and high gas barrier properties And durability such as crack resistance can be maintained. Further, in this case, by reducing the thickness per layer, the film layer as a whole becomes pliable and the workability is improved.
In order to further exert these effects, it is preferable that the gas barrier layer and the elastic layer are alternately laminated, and it is preferable that the surface of the film layer is formed by the elastic layer. It is also preferable that the surface of the film layer is formed by a gas barrier layer. Therefore, the number of gas barrier layers is preferably three or more, and the number of elastic layers is preferably four or more. In addition, from the viewpoint of sufficiently maintaining the gas barrier property and crack resistance of the inner liner, the total number of the gas barrier layer and the elastic layer is preferably 7 or more, more preferably 11 or more, More preferably, the number of layers is 15 or more. The upper limit of the total number of the gas barrier layer and the elastic layer is not particularly limited.

  The thickness of the film layer is preferably from 0.1 μm to 1,000 μm, more preferably from 0.5 μm to 750 μm, still more preferably from 1 μm to 500 μm, and still more preferably from 1 μm to 150 μm. By setting the thickness of the film layer in the above range, the average thickness of one of the gas barrier layer and the elastic layer in the above range is combined with the gas barrier property, bending resistance, crack resistance, durability, and stretching. Properties and the like can be further improved. Here, the thickness of the film layer is obtained by measuring the thickness of the cross section at an arbitrarily selected point of the film layer.

  The adhesive layer of the inner liner manufactured by the method of the present invention contains at least a polystyrene-based thermoplastic elastomer, and may contain other components in addition to the polystyrene-based thermoplastic elastomer, or may be made of only the polystyrene-based thermoplastic elastomer. May be. When the adhesive layer contains at least a polystyrene-based thermoplastic elastomer, the workability is good because the adhesiveness to the rubber member is high and the adhesiveness of the adhesive layer is not too high. In particular, since the adhesive layer of the inner liner produced by the method of the present invention does not have too high a tackiness, even if the adhesive layer is disposed on both surfaces of the film layer, in the green tire molding step, the adhesive is applied to the molding drum. Is suppressed, and workability can be improved.

  The above-mentioned polystyrene-based thermoplastic elastomer has an aromatic vinyl-based polymer block (hard segment) and a rubber block (soft segment), and the aromatic vinyl-based polymer portion forms a physical cross-link to serve as a bridge point. On the other hand, the rubber block imparts rubber elasticity. The polystyrene-based thermoplastic elastomer can be classified according to the arrangement of soft segments in the molecule. For example, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), Styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and the like. A block copolymer of crystalline polyethylene and ethylene-butylene-styrene random copolymer obtained by hydrogenating a block copolymer of polybutadiene and butadiene-styrene random copolymer, and polybutadiene or ethylene-butadiene random Obtained by hydrogenating a block copolymer of the polymer and polystyrene, for example, also include diblock copolymer of crystalline polyethylene and polystyrene. Among them, styrene-isobutylene-styrene block copolymer (SIBS) and styrene-butadiene are preferable in terms of balance of mechanical strength, heat resistance, weather resistance, chemical resistance, gas barrier property, flexibility, workability, and the like. -Styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer (SIS) are preferred.

  In the inner liner manufactured by the method of the present invention, the adhesive layer further contains a thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer, the polystyrene-based thermoplastic elastomer contained in the adhesive layer, and the polystyrene-based The mass ratio of the thermoplastic elastomer other than the thermoplastic elastomer is preferably in the range of 25:75 to 75:25. Since the adhesive layer contains a polystyrene-based thermoplastic elastomer and a thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer, the interface between the film layer and the adhesive layer can be provided with irregularities. It has a three-dimensionally complicated structure, and the adhesion between the film layer and the adhesive layer can be improved by the anchor effect. If the mass ratio of the polystyrene-based thermoplastic elastomer to the thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer is in the range of 25:75 to 75:25, the polystyrene-based thermoplastic elastomer is added to the polystyrene-based thermoplastic elastomer. The effect of blending a thermoplastic elastomer other than the elastomer is sufficiently exhibited, and the adhesiveness between the film layer and the adhesive layer is further improved.

  Here, the thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer contained in the adhesive layer includes polyurethane-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polydiene-based thermoplastic elastomer, polyvinyl chloride-based thermoplastic elastomer, and chlorinated polyethylene. Examples include a thermoplastic thermoplastic elastomer, a polyester-based thermoplastic elastomer, a polyamide-based thermoplastic elastomer, and a fluororesin-based thermoplastic elastomer. Among these, a polyurethane-based thermoplastic elastomer is preferable. These thermoplastic elastomers may be used alone or in a combination of two or more.

  The adhesive layer of the inner liner manufactured by the method of the present invention contains the polystyrene-based thermoplastic elastomer and the polyurethane-based thermoplastic elastomer, and has a mass ratio of the polystyrene-based thermoplastic elastomer to the polyurethane-based thermoplastic elastomer of 25: More preferably, it is in the range of 75 to 75:25. Since the adhesive layer contains the polystyrene-based thermoplastic elastomer and the polyurethane-based thermoplastic elastomer in a mass ratio of 25:75 to 75:25, the adhesiveness between the film layer and the adhesive layer is significantly improved. . Here, the polyurethane-based thermoplastic elastomer that can be used for the adhesive layer is the same as the polyurethane-based thermoplastic elastomer (TPU) described in the section of the above-described elastic layer. The polyurethane thermoplastic elastomer used for the elastic layer may be the same or different.

  In the adhesive layer of the inner liner manufactured by the method of the present invention, the polystyrene-based thermoplastic elastomer preferably has a styrene content of 40% by mass to 55% by mass, and more preferably 40% by mass to 48% by mass. More preferred. When the styrene content of the polystyrene-based thermoplastic elastomer used for the adhesive layer is 40% by mass or more, the adhesive force with the rubber member is further improved, and the glass transition temperature (Tg) of the adhesive layer is high, so that vulcanization is performed. Even under high temperature conditions, the adhesive layer hardly flows, and the workability when vulcanizing a green tire incorporating an inner liner is further improved. It is possible to reduce the possibility that the adhesive layer is broken during running of the tire which is soft and incorporates the inner liner.

  The adhesive layer preferably has an average thickness of 0.001 μm to 40 μm. When the average thickness of one layer of the adhesive layer is 0.001 μm or more, the adhesiveness with an adjacent rubber member can be further improved, and when it is 40 μm or less, unnecessary increase in weight can be avoided. .

  The composition used for at least one of the gas barrier layer and the elastic layer described above, and the composition used for the adhesive layer include a metal salt, a radical crosslinking agent, a phosphoric acid compound, an additive such as a carboxylic acid and a boron compound, It can be appropriately selected and included within a range that does not impair the object of the present invention.

  When the raw material composition used for the gas barrier layer, the elastic layer, and the adhesive layer contains a metal salt, extremely excellent interlayer adhesion is exhibited. Due to such excellent interlayer adhesion, the inner liner has high durability. The reason why the metal salt improves interlayer adhesion is not necessarily clear, but, for example, a bond formation reaction that occurs between a thermoplastic resin or the like and a thermoplastic elastomer or the like in the raw material composition is caused by the presence of the metal salt. It may be accelerated. Examples of such a bond forming reaction include a hydroxyl group exchange reaction that occurs between a carbamate group of a polyurethane-based thermoplastic elastomer (TPU) and a hydroxyl group of an ethylene-vinyl alcohol copolymer (EVOH), and a polyurethane-based thermoplastic elastomer. An addition reaction of the hydroxyl group of the ethylene-vinyl alcohol copolymer (EVOH) to the remaining isocyanate group in (TPU) may be considered.

The metal salt is not particularly limited, but an alkali metal salt, an alkaline earth metal salt or a d-block metal salt described in the fourth period of the periodic table is preferable in that the interlayer adhesion is further increased. . Among these, alkali metal salts or alkaline earth metal salts are more preferable, and alkali metal salts are particularly preferable.
Examples of the alkali metal salt include an aliphatic carboxylate such as lithium, sodium, and potassium, an aromatic carboxylate, a phosphate, and a metal complex. Specific examples of the alkali metal salt include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, and sodium salt of ethylenediaminetetraacetic acid. Among these, sodium acetate, potassium acetate, and sodium phosphate are particularly preferable because they are easily available.
Examples of the alkaline earth metal salts include acetates and phosphates such as magnesium, calcium, barium, and beryllium. Among them, acetate or phosphate of magnesium or calcium is particularly preferable because it is easily available. When such an alkaline earth metal salt is contained, there is also an advantage that the amount of a resin adhered to a thermally degraded resin or a thermoplastic elastomer during melt molding can be reduced in a die.
Examples of the metal salt of the d-block metal described in the fourth period of the periodic table include, for example, carboxylates, phosphates, such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc; Acetyl acetonate salt and the like can be mentioned.

  The content of the metal salt in the raw material composition is preferably 1 mass ppm or more, more preferably 5 mass ppm or more, still more preferably 10 mass ppm or more, even more preferably 20 mass ppm or more, in terms of metal element. Particularly preferred is 50 ppm by mass or more. Further, the content of the metal salt in the raw material composition is preferably 10,000 mass ppm or less, more preferably 5,000 mass ppm or less, still more preferably 1,000 mass ppm or less, in terms of the metal element, and more preferably 500 mass ppm. ppm or less is still more preferable, and 300 ppm by mass or less is particularly preferable. If the content of the metal salt in the raw material composition is 1 mass ppm to 10,000 mass ppm in terms of the metal element, the adhesiveness with the adjacent other layer is further increased, so that the gas barrier property and the bending resistance are reduced. It can be further improved.

Further, when the raw material composition contains a radical crosslinking agent, by irradiating a layer made of the composition with an active energy ray, a crosslinking effect at the time of active energy ray irradiation is promoted, and interlayer adhesion is further improved, Gas barrier properties are further enhanced. Further, the irradiation amount of the active energy ray can be reduced as compared with the case where no radical crosslinking agent is present.
Examples of the radical crosslinking agent include poly (meth) acrylates of polyhydric alcohols such as trimethylolpropane trimethacrylate, diethylene glycol diacrylate, and neophenylene glycol diacrylate, triallyl isocyanurate, triallyl cyanurate, and the like. it can. These may be used alone or in combination of two or more.
The content of the radical crosslinking agent in the raw material composition is preferably in the range of 0.01% by mass to 10% by mass, more preferably in the range of 0.05% by mass to 9% by mass, and more preferably in the range of 0.1% by mass to 8% by mass. The range of mass% is particularly preferable from the viewpoint of the balance between the crosslinking effect and economy.
The method for containing the radical crosslinking agent in the raw material composition is not particularly limited, and for example, a method of melting and kneading the raw material composition using a twin-screw extruder or the like can be used.

In addition, when the raw material composition contains a phosphoric acid compound, the thermal stability of the film layer and the adhesive layer at the time of melt molding can be improved. Examples of the phosphoric acid compound include various acids such as phosphoric acid and phosphorous acid, and salts thereof. The phosphate may be contained, for example, in any form of a first phosphate, a second phosphate, and a third phosphate, and the counter cation species is not particularly limited. Alkaline earth metal ions are preferred. In particular, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium hydrogen phosphate, or potassium hydrogen phosphate is preferred because of its high thermal stability improving effect.
The content of the phosphoric acid compound (the content of the phosphoric acid compound in the dried raw material composition in terms of phosphate radical) is preferably 1 mass ppm or more, more preferably 10 mass ppm or more, and still more preferably 30 mass ppm or more. Further, the content of the phosphoric acid compound is preferably 10,000 mass ppm or less, more preferably 1,000 mass ppm or less, and still more preferably 300 mass ppm or less. If the content of the phosphoric acid compound is lower than 1 ppm by mass, coloring during melt molding may become intense. In particular, when the thermal history is repeated, the tendency is remarkable, so that a molded product obtained by molding the composition pellet may have poor recoverability. On the other hand, when the content of the phosphoric acid compound exceeds 10,000 ppm by mass, gels and bumps may be easily generated during molding.

Further, by containing a carboxylic acid in the raw material composition, there is an effect of controlling the pH of the composition, preventing gelation, and improving thermal stability. As the carboxylic acid, acetic acid or lactic acid is preferred from the viewpoint of cost and the like.
The content of the carboxylic acid (the content of the carboxylic acid in the dry raw material composition) is preferably at least 1 ppm by mass, more preferably at least 10 ppm by mass, even more preferably at least 50 ppm by mass. Further, the content of the carboxylic acid is preferably 10,000 mass ppm or less, more preferably 1,000 mass ppm or less, and still more preferably 500 mass ppm or less. When the content of the carboxylic acid is lower than 1 ppm by mass, coloring may occur during melt molding. When the content of the carboxylic acid is 10,000 ppm by mass or less, good interlayer adhesion can be obtained.

Further, by containing a boron compound in the raw material composition, there is an effect of improving thermal stability. In detail, when a boron compound is added to the raw material composition, it is considered that a chelate compound is generated between the boron compound and the thermoplastic resin or the thermoplastic elastomer, and by using such a thermoplastic resin or the thermoplastic elastomer, It is possible to improve the thermal stability and the mechanical properties as compared with ordinary thermoplastic resins and thermoplastic elastomers. Examples of the boron compound include boric acids, boric acid esters, borates, and hydrogenated boric acids. Specifically, examples of the boric acids include orthoboric acid (H ₃ BO ₃ ), metaboric acid, and tetraboric acid, and examples of the borate esters include triethyl borate and trimethyl borate. Examples of the borate include alkali metal salts, alkaline earth metal salts, and borax of the various boric acids. Of these, orthoboric acid is preferred.
The content of the boron compound (the content in terms of boron of the boron compound in the dry raw material composition) is preferably 1 ppm by mass or more, more preferably 10 ppm by mass or more, and even more preferably 50 ppm by mass or more. Further, the content of the boron compound is preferably 2,000 mass ppm or less, more preferably 1,000 mass ppm or less, and even more preferably 500 mass ppm or less. If the content of the boron compound is lower than 1 mass ppm, the effect of improving the thermal stability by adding the boron compound may not be obtained. On the other hand, when the content of the boron compound exceeds 2,000 mass ppm, gelation is likely to occur, and molding failure may occur.

  The method of including the metal salt, the phosphoric acid compound, the carboxylic acid, and the boron compound in the raw material composition is not particularly limited, and for example, kneading by adding to the composition when preparing a pellet or the like of the composition. Is preferably adopted. The method of adding to the raw material composition is also not particularly limited, but a method of adding as a dry powder, a method of adding as a paste impregnated with a solvent, a method of adding in a state of being suspended in a liquid, and a method of dissolving in a solvent And a method of adding as a solution. Among these, from the viewpoint of homogenous dispersion, a method of dissolving in a solvent and adding as a solution is preferable. The solvent used in these methods is not particularly limited, but water is preferably used from the viewpoints of solubility of the additive, cost, ease of handling, and completeness of the working environment.

  Further, as a method of containing the metal salt, the phosphoric acid compound, the carboxylic acid, and the boron compound, a method of immersing pellets or strands of the raw material composition in a solution in which those substances are dissolved can also be uniformly dispersed. It is preferred in that respect. Also in this method, water is suitably used as the solvent for the same reason as described above.

  The raw material composition preferably contains a compound having a conjugated double bond having a molecular weight of 1,000 or less. By containing such a compound, the hue of the composition is improved, so that a film layer having a good appearance can be obtained. Examples of such a compound include a conjugated diene compound having a structure in which at least two carbon-carbon double bonds and one carbon-carbon single bond are alternately connected, and three carbon-carbon double bonds. And a conjugated polyene compound having a structure in which two or more carbon-carbon single bonds are connected alternately, and a conjugated polyene compound having a structure in which a larger number of carbon-carbon double bonds and carbon-carbon single bonds are connected alternately And conjugated triene compounds such as 2,4,6-octatriene. The compound having a conjugated double bond may have a plurality of conjugated double bonds independently in one molecule. For example, a compound having three conjugated trienes in the same molecule such as tung oil may be used. included.

  The compound having a conjugated double bond includes, for example, a carboxy group and a salt thereof, a hydroxyl group, an ester group, a carbonyl group, an ether group, an amino group, an imino group, an amide group, a cyano group, a diazo group, a nitro group, a sulfone group, It may have other various functional groups such as a sulfoxide group, a sulfide group, a thiol group, a sulfonic acid group and a salt thereof, a phosphoric acid group and a salt thereof, a phenyl group, a halogen atom, a double bond and a triple bond. Such a functional group may be directly bonded to a carbon atom in the conjugated double bond, or may be bonded to a position remote from the conjugated double bond. The multiple bond in the functional group may be located at a position capable of conjugation with the conjugated double bond. For example, 1-phenylbutadiene having a phenyl group, sorbic acid having a carboxy group, and the like may also be used. Included in compounds having heavy bonds. Specific examples of the compound include, for example, 2,4-diphenyl-4-methyl-1-pentene, 1,3-diphenyl-1-butene, 2,3-dimethyl-1,3-butadiene, 4-methyl- Examples include 1,3-pentadiene, 1-phenyl-1,3-butadiene, sorbic acid, and myrcene.

  The conjugated double bond in the compound having a conjugated double bond means not only an aliphatic conjugated double bond such as 2,3-dimethyl-1,3-butadiene and sorbic acid, but also 2,4-diphenyl. Conjugated double bonds of aliphatic and aromatic such as -4-methyl-1-pentene and 1,3-diphenyl-1-butene are also included. However, from the viewpoint of obtaining a film layer having a better appearance, a compound containing a conjugated double bond between aliphatic groups is preferable, and a carboxy group and a salt thereof, including a conjugated double bond having a polar group such as a hydroxyl group. Compounds are also preferred. Further, a compound having a polar group and containing a conjugated double bond between aliphatic groups is particularly preferable.

  The molecular weight of the compound having a conjugated double bond is preferably 1,000 or less. When the molecular weight exceeds 1,000, the surface smoothness and extrusion stability of the film layer may be deteriorated. The content of the compound having a conjugated double bond having a molecular weight of 1,000 or less is preferably 0.1 mass ppm or more, more preferably 1 mass ppm or more, and more preferably 3 mass ppm or more, from the viewpoint of the effect to be exhibited. More preferably, the content is 5 ppm by mass or more. In addition, the content of the compound is preferably 3,000 mass ppm or less, more preferably 2,000 mass ppm or less, still more preferably 1,500 mass ppm or less, and 1,000 mass, from the viewpoint of the effect to be exhibited. ppm or less is particularly preferred.

  The method of adding the compound having a conjugated double bond is not particularly limited, but when the compound having a conjugated double bond is added to the resin composition for a gas barrier layer, the thermoplastic resin is polymerized. It is preferable to add it after the addition and before the saponification from the viewpoint of improving the surface smoothness and the extrusion stability. Although the reason for this is not necessarily clear, it is considered that the compound having a conjugated double bond has an action of preventing the thermoplastic resin from being deteriorated before and / or during the saponification reaction.

  The inner liner manufactured by the method of the present invention preferably has a peeling resistance of an adjacent layer (for example, a gas barrier layer and an elastic layer, a gas barrier layer and an adhesive layer, an elastic layer and an adhesive layer) from the viewpoint of interlayer adhesion. It is at least 25 N / 25 mm, more preferably at least 27 N / 25 mm, even more preferably at least 30 N / 25 mm. Here, the peeling resistance is a value measured by a T-type peeling test at a pulling rate of 50 mm / min in an atmosphere of 23 ° C. and 50% RH in accordance with JIS K 6854.

In the method for manufacturing an inner liner of a pneumatic tire according to the present invention, the film layer and the adhesive layer are laminated by co-extrusion. By laminating the film layer and the adhesive layer by co-extrusion, the number of steps is reduced and the productivity is improved as compared with the case where the film layer and the adhesive layer are separately formed and bonded, and the adhesion to the film layer is also improved. Interlayer adhesion with the layer is also improved. In the case where the film layer and the adhesive layer are separately manufactured and bonded, the actual contact area between the film layer and the adhesive layer is smaller than when the film layer and the adhesive layer are laminated by co-extrusion. By laminating the layer and the adhesive layer by co-extrusion, the actual contact area between the film layer and the adhesive layer is increased, and the interlayer adhesion between the film layer and the adhesive layer is improved.
Specific examples of the method for producing the inner liner of the present invention include a raw material for a gas barrier layer containing at least a thermoplastic resin, a raw material for an elastic layer containing at least a polyurethane-based thermoplastic elastomer, and an adhesive layer containing at least a polystyrene-based thermoplastic elastomer. A raw material is prepared, and a method of producing an inner liner having a gas barrier layer, an elastic layer, and an adhesive layer by a multilayer coextrusion method using these raw materials is exemplified.

  In the multilayer co-extrusion method, a raw material for forming a gas barrier layer, a raw material for forming an elastic layer, and a raw material for forming an adhesive layer are heated and melted, and passed through respective flow paths from different extruders and pumps. The inner liner is formed by being supplied to an extrusion die, being extruded in multiple layers from the extrusion die, and then being laminated and bonded. As the extrusion die, for example, a multi-manifold die, a field block, a static mixer, or the like can be used.

In the method for manufacturing an inner liner of a pneumatic tire according to the present invention, the film layer and the adhesive layer laminated by co-extrusion as described above are then irradiated with active energy rays. By irradiating an active energy ray to promote a crosslinking reaction in the adhesive layer, the flow of the adhesive layer can be suppressed in the vulcanization step after the incorporation into a green tire as described later, and the vulcanization step Workability is improved.
Irradiation with an active energy ray also promotes a cross-linking reaction between the film layer and the adhesive layer, and improves the interlayer adhesion between the film layer and the adhesive layer. Further, by irradiating with an active energy ray, a cross-linking reaction between the gas barrier layer and the elastic layer in the film layer is promoted, and the interlayer adhesion between the gas barrier layer and the elastic layer is also improved. Furthermore, by irradiating with active energy rays, the adhesiveness between layers is enhanced. In addition, by irradiating the inner liner with active energy rays, the shape retention of each layer of the inner liner in the vulcanization process during tire manufacturing is improved, and the adhesion to the bladder when the inner liner peels off from the bladder Can be improved.

  The active energy ray refers to an electromagnetic wave or a charged particle beam having an energy quantum, specifically, an ultraviolet ray, a γ ray, an electron beam, or the like. Among these active energy rays, an electron beam is preferable from the viewpoint of the effect of improving interlayer adhesion. By using an electron beam as the active energy ray, a cross-linking reaction between layers is further promoted, and the interlayer adhesion of the inner liner can be further improved.

When irradiating an electron beam, various electron beam accelerators such as Cockloft-Walton type, Van degraft type, resonance transformer type, insulating core transformer type, or linear type, dynamitron type, and high frequency type are used as the electron beam source. It is preferable that the irradiation be performed at an acceleration voltage of 100 kV to 500 kV and an irradiation dose of 5 kGy to 600 kGy.
When ultraviolet rays are used as the active energy rays, it is preferable to irradiate an ultraviolet ray having a wavelength of 190 nm to 380 nm. The ultraviolet source is not particularly limited, and for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a carbon arc lamp, and the like are used.

<Method of manufacturing pneumatic tires>
Next, a method for manufacturing a pneumatic tire according to the present invention will be described in detail based on its embodiment.
FIG. 2 is a partial cross-sectional view of an example of the pneumatic tire manufactured by the method for manufacturing a pneumatic tire according to the present invention. The tire shown in FIG. 2 has a pair of beads 1 and a pair of sidewalls 2, and a tread 3 connected to both sidewalls 2, and extends in a toroidal shape between the pair of beads 1. A carcass 4 for reinforcing these parts 1, 2, 3; and a belt 5 composed of two belt layers disposed radially outward of a crown portion of the carcass 4 in the tire radial direction. An inner liner 6 is arranged on the inner surface of the inner tire.
Here, in the pneumatic tire manufactured by the method of the present invention, the inner liner 6 includes the above-described inner liner manufactured by the method of manufacturing an inner liner of the present invention. Since the pneumatic tire manufactured by the method of the present invention has the above-described inner liner having high adhesiveness to the rubber member, peeling of the inner liner 6 is suppressed, and internal pressure retention is high. Further, since the peeling between the film layer and the adhesive layer in the inner liner is also suppressed, the durability of the inner liner 6 is high in the pneumatic tire manufactured by the method of the present invention.

In the tire shown in FIG. 2, the carcass 4 is composed of one carcass ply, and a main body portion extending in a toroidal shape between a pair of bead cores 7 buried in the bead portion 1, and around each bead core 7. In the pneumatic tire manufactured according to the method of the present invention, the number of plies and the structure of the carcass 4 are limited to the above. Not something.
In the tire shown in FIG. 2, the belt 5 is composed of two belt layers. However, in the pneumatic tire manufactured by the method of the present invention, the number of belt layers constituting the belt 5 is not limited to this. is not.

  Further, for the tread portion, sidewall portion, bead portion, and the like of the pneumatic tire manufactured by the method of the present invention, materials, shapes, and arrangements used for those portions of a normal tire can be appropriately adopted. In addition, as the gas to be filled in the tire, there can be used an inert gas such as nitrogen, argon, helium or the like, in addition to normal or air having adjusted oxygen partial pressure.

  In the manufacturing method of the pneumatic tire of the present invention, on the inner surface of the tire, the inner liner extends in the tire circumferential direction, and the ends of the inner liner in the tire circumferential direction are arranged so as to overlap in the tire radial direction, Preferably, both ends of the inner liner in the tire circumferential direction are parallel to the tire width direction, and the overlap width between the ends of the inner liner in the tire circumferential direction is preferably in the range of 5 mm to 20 mm. In a case where both ends of the inner liner in the tire circumferential direction are parallel to the tire width direction, if the overlap width is in the range of 5 mm to 20 mm, peeling of the joint after running the tire can be suppressed.

  In the method for manufacturing a pneumatic tire according to the present invention, as shown in FIG. 3, the inner liner extends in the tire circumferential direction on the inner surface of the tire, and ends of the inner liner in the tire circumferential direction are connected to each other. It is also preferable that the inner liner is disposed so as to be overlapped in the radial direction, and the ends of the inner liner have peaks and valleys alternately. Since the ends of the inner liner have alternating peaks and valleys (that is, the shape of the ends is so-called "jagged"), the shear stress applied to the joint between the ends can be dispersed and reduced. As a result, peeling of the joint at the time of molding the green tire and peeling of the joint after running the tire can be suppressed.

FIG. 3 is a partial cross-sectional view of an example of a pneumatic tire manufactured by the method of the present invention, in which the inner liner end is joined, as viewed from the tire inner surface. In the overlapping portion between the ends of the inner liner shown in FIG. 3, one end (indicated by a dotted line in FIG. 3) 100a of the inner liner located outside in the tire radial direction is located inside the tire radial direction (that is, the innermost surface of the tire). position is covered by the other end portion 100b of the inner liner, one end 100a of the inner liner has alternating with crests T _a and valley portions B _a, also, the other end portion 100b of the inner liner also has alternating between peak portions _{T b} and valley portions _{B b.} In FIG. 3, the cut surfaces of the end portions 100a and 100b in the tire circumferential direction of the inner liner extend along the tire width direction as a whole, but in the pneumatic tire manufactured by the method of the present invention, The cut surface of the end of the inner liner in the tire circumferential direction may be inclined with respect to the tire width direction.
Here, in FIG. 3, are arranged such that the valleys B _b of the other end portion 100b of the ridges T _a and the inner liner of the one end portion 100a of the inner liner are close, also, one end of the inner liner and mountain portions T _b parts 100a valleys B _a and the other end portion 100b of the inner liner is arranged adjacent.

3, ridges _{T a} of the one end portion 100a of the inner liner, valleys _{B a} also, crests _{T b} of the other end portion 100b of the inner liner, valley _{B b} is two both the cut surface formed from planar, and, the two planes are formed intersecting angle T _alpha vertex at the crest T _a, Yamabe T _b the angle T _beta vertex of the angle valley valley B _a B _alpha, the angle B _beta valley valley _{B b,} it is preferable that both in the range of 45 ° to 120 °. If the angle of the peak of the peak and the angle of the bottom of the valley are 45 ° or more, the peak of the peak and the bottom of the valley are not sharp, so when molding a raw tire or after running the tire. Can be further suppressed, and if it is 120 ° or less, the separation of the joint after running the tire can be further suppressed.

  In addition, in FIG. 3, the overlap width D between the ends 100 a and 100 b of the inner liner in the tire circumferential direction is preferably in a range of 1 mm to 13 mm. If the overlap width D is 1 mm or more, the peeling of the joint during molding of the green tire can be further suppressed, and if it is 13 mm or less, the peeling of the joint after running the tire can be further suppressed.

  Further, in the pneumatic tire manufactured by the method of the present invention, it is preferable that a rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm is provided on the outer side in the tire radial direction of the inner liner. More preferably comprises a rubber-like elastic layer of 0.2 mm to 0.6 mm. By disposing a rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm on the outer side in the tire radial direction of the inner liner, it is possible to suppress the occurrence of cracks in the inner liner, It is possible to improve the peeling resistance of each other, and when the thickness of the rubber-like elastic layer is 0.2 mm to 0.6 mm, while further suppressing the occurrence of cracks in the inner liner, The peeling resistance between the ends can be further improved.

  FIG. 4 is a partial cross-sectional view of an example of a pneumatic tire manufactured by the method of the present invention, viewed from the tire width direction, at a joint portion of an inner liner end. By adhering a rubber-like elastic layer having a thickness of 0.1 mm or more to the inner liner, it is possible to suppress the occurrence of cracks in the inner liner. However, as shown in FIG. When a composite to which the body layer 8 is adhered is prepared, and the composite is extended in the tire circumferential direction on the inner surface of the tire, the rubber-like elastic layer 8 is formed at the overlapping portion between the ends of the composite. Due to the thickness H of the tire, there is a possibility that the peeling resistance between the ends of the composite is reduced by a moment M generated by a shear stress in a direction perpendicular to the expanding force F of the tire. On the other hand, by setting the thickness H of the rubber-like elastic layer 8 to 1.0 mm or less, the moment M generated by shear stress in a direction perpendicular to the expanding force F of the tire can be reduced. The peeling resistance between the ends can be improved.

  In the pneumatic tire manufactured by the method of the present invention, on the tire inner surface, the inner liner extends in the tire circumferential direction, and the ends of the inner liner in the tire circumferential direction overlap in the tire radial direction, and A rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm on the outer side in the tire radial direction of a portion where the end portions of the inner liner in the tire circumferential direction overlap each other. More preferably, a rubber-like elastic layer having a thickness of 0.2 mm to 0.6 mm is further provided.

  FIG. 5 is a partial cross-sectional view of another example of a pneumatic tire manufactured by the method of the present invention, showing a joint portion at an inner liner end, as viewed from the tire width direction. In the overlapping portion between the ends 100a and 100b of the inner liner shown in FIG. 5, one end 100a of the inner liner located on the radially outer side of the tire is located on the inner side of the tire radially inner side (that is, the innermost surface of the tire). A rubber-like elastic layer 8 is disposed outside the one end portion 100b in the tire radial direction outside of the overlapping portion between the inner liner ends 100a and 100b. At this time, as one mode of the joining portion in which the one end portion 100a of the inner liner and the other end portion 100b of the inner liner overlap in the tire radial direction, one form of the inner liner (that is, the gas barrier layer + elastic layer + adhesive layer) is used. One end and the other end are bonded via a rubber-like elastic material layer, and as another form, a form in which both ends of the inner liner are arranged in direct contact with each other. No. Here, the thickness H of the rubber-like elastic layer 8 is preferably in the range of 0.1 to 1 mm, and more preferably in the range of 0.2 to 0.6 mm. When the thickness H of the rubber-like elastic layer 8 is in the above range, at -20 ° C, the stress generated in the gas barrier layer constituting the inner liner is relaxed while maintaining the followability to the carcass, and the breakage of the gas barrier layer and The generation of cracks can be suppressed. Further, even if the gas barrier layer breaks and cracks occur, it is possible to suppress the progress of the breaks and cracks.

As described above, by attaching the rubber-like elastic material layer to the inner liner, it is possible to suppress the occurrence of cracks in the inner liner. However, as shown in FIG. 4, the rubber-like elastic material layer is attached to the inner liner in advance. When the composite attached is prepared and the composite is extended in the tire circumferential direction on the inner surface of the tire, the thickness H of the rubber-like elastic layer 8 in the overlapping portion between the ends of the composite is adjusted. Due to the moment M generated by the shear stress in the direction perpendicular to the expansion force F of the tire, the peeling resistance between the ends of the composite may decrease.
On the other hand, when the rubber-like elastic layer is pasted on the inner liner in advance, as shown in FIG. 5, only the inner liner 100 is extended in the tire circumferential direction on the inner surface of the tire, and When the rubber-like elastic layer 8 is separately arranged on the tire radial outer side of the overlapping portion between the end portions 100a and 100b in the tire direction, the inner liner has an inner portion in the overlapping portion between the circumferential end portions 100a and 100b of the inner liner. Since the rubber-like elastic layer 8 does not intervene between the ends 100a and 100b of the liner, the moment M generated by the shear stress in the direction perpendicular to the expanding force F of the tire can be further reduced, and the inner liner end 100a , 100b can be further improved. When the thickness H of the rubber-like elastic layer 8 is 0.1 mm or more, the occurrence of cracks in the inner liner can be suppressed, and when it is 1.0 mm or less, an increase in tire weight can be suppressed. .

The dynamic storage elastic modulus E ′ of the rubber elastic layer 8 at −20 ° C. is preferably 1.0 × 10 ⁵ to 1.0 × 10 ⁷ Pa, and 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ . more preferably from 0 × ¹⁰ 6 Pa, and even more preferably ^{1.0 × 10 5 Pa~5.0 × 10 5} Pa. When the dynamic storage modulus E ′ is 1.0 × 10 ⁵ Pa or more, the workability in kneading the rubber composition used for the rubber-like elastic layer 8 can be sufficiently ensured, and the dynamic storage When the elastic modulus E ′ is 1.0 × 10 ⁷ Pa or less, deformation of the carcass can be reduced, deformation of the gas barrier layer is suppressed, and crack resistance in a low-temperature environment is improved.

  The rubber component of the rubber composition used for the rubber-like elastic layer 8 is not particularly limited, and for example, a diene rubber is used. As the diene rubber, specifically, natural rubber (NR), isoprene rubber (IR), cis-1,4-polybutadiene rubber (BR), syndiotactic-1,2-polybutadiene rubber (1, BR) And styrene-butadiene copolymer rubber (SBR). These diene rubbers may be used alone or in combination of two or more.

The rubber composition used for the rubber-like elastic layer 8 may contain, in addition to the rubber component, compounding agents commonly used in the rubber industry, for example, a softener, a vulcanizing agent, a vulcanization accelerator, a filler, and a tackifier. Resins, anti-aging agents, anti-scorch agents, zinc white, stearic acid, and the like can be appropriately added according to the purpose. Commercially available products can be suitably used as these compounding agents. The rubber composition used for the rubber-like elastic layer 8 can be prepared by mixing the respective components using, for example, a Banbury mixer or a roll.

The rubber composition used for the rubber-like elastic layer 8 preferably contains a softener. As the softener, any of a mineral oil-based softener, a vegetable oil-based softener, and a synthetic softener can be used. Mineral oil softeners include petroleum softeners and coal tar softeners. Examples of the petroleum-based softener include process oil, extender oil, asphalt-based, paraffins, liquid paraffin, petrolatum, and petroleum resin. Examples of the coal tar softener include coal tar and coumarone indene resin.
As vegetable oil-based softeners, fatty oil-based softeners such as soybean oil, palm oil, pine oil, castor oil, linseed oil, rapeseed oil, coconut oil, tall oil, waxes such as factice, beeswax, carnauba wax, and lanolin And fatty acids such as linoleic acid, palmitic acid, stearic acid and lauric acid.
Examples of the synthetic softener include a synthetic resin softener, a liquid rubber or oligomer, a low-molecular plasticizer, a high-molecular plasticizer, and a reactive plasticizer. Examples of the synthetic resin softener include phenol aldehyde resin, styrene resin, atactic polypropylene and the like. Examples of the liquid rubber or oligomer include polybutene, liquid butadiene rubber, liquid isoprene rubber, liquid acrylonitrile butadiene rubber, and the like. Examples of the low-molecular plasticizer include dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and the like.
Further, the softener described above is preferably contained in an amount of 5 to 50 parts by mass, more preferably 5 to 40 parts by mass, and more preferably 5 to 30 parts by mass based on 100 parts by mass of the rubber component. More preferred. By setting the amount of the softener to the rubber component within the above range, the dynamic storage elastic modulus E ′ of the rubber-like elastic layer 8 at −20 ° C. is 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ Pa. It can be. As the softener, one selected from the above-described softeners can be used, or a plurality of softeners can be used in combination.

It is preferable that the rubber composition used for the rubber-like elastic layer 8 contains a vulcanizing agent and a vulcanization accelerator. Examples of the vulcanizing agent include sulfur. When sulfur is used as a vulcanizing agent, the compounding amount thereof is preferably in the range of 0.1 to 10.0 parts by mass, and more preferably in the range of 1.0 to 5.0 parts by mass, based on 100 parts by mass of the rubber component. The range is more preferred. Examples of the vulcanization accelerator include thiazoles such as M (2-mercaptobenzothiazole), DM (dibenzothiazolyl disulfide), and CZ (N-cyclohexyl-2-benzothiazolylsulfenamide); Examples include guanidine-based vulcanization accelerators such as DPG (diphenylguanidine). The compounding amount of these vulcanization accelerators is preferably in the range of 0.1 to 5.0 parts by mass, more preferably 0.2 to 3.0 parts by mass, based on 100 parts by mass of the rubber component.

The rubber composition used for the rubber-like elastic layer 8 preferably contains a filler. As the filler, an inorganic filler and / or carbon black is used. The inorganic filler is not particularly limited, but preferably includes, for example, silica, aluminum hydroxide, aluminum oxide, magnesium oxide, montmorillonite, mica, smectite, organic montmorillonite, organic mica, and organic smectite by a wet method. it can. These may be used alone or in a combination of two or more.
On the other hand, as the carbon black, any one conventionally used as a reinforcing filler for rubber can be appropriately selected and used. For example, FEF, SRF, HAF, ISAF, SAF, GPF, etc. Is mentioned.
The amount of the filler is preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component, together with carbon black, from the viewpoint of tackiness and peeling resistance.

The rubber composition used for the rubber-like elastic layer 8 preferably contains a tackifying resin. The tackifier as resins, such as phenolic resins, terpene resins, modified terpene resins, hydrogenated terpene resins, rosin resins, C ₅ petroleum resins, C ₉ petroleum resins, xylene resins, coumarone - indene resins, di Examples thereof include a cyclopentadiene resin and a styrene resin. Among them, a phenol resin, a terpene resin, a modified terpene resin, a hydrogenated terpene resin, and a rosin resin are preferable.
Examples of the phenolic resin include a resin obtained by condensing pt-butylphenol and acetylene in the presence of a catalyst, and a condensate of alkylphenol and formaldehyde. Further, as the terpene resin, modified terpene resin, hydrogenated terpene resin, for example, terpene resins such as β-pinene resin and α-pinene resin, hydrogenated terpene resin obtained by hydrogenating these, Modified terpene resins obtained by reacting terpene and phenol with a Friedel-Crafts type catalyst or condensing with formaldehyde can be mentioned. Examples of the rosin-based resin include a natural resin rosin and a rosin derivative obtained by modifying the rosin with hydrogenation, disproportionation, dimerization, esterification, lime, or the like.
These resins may be used alone or in combination of two or more. Among them, a phenol resin is particularly preferable.
The tackifier resin is preferably used in an amount of 5 parts by mass or more, more preferably 5 to 40 parts by mass, and still more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The method for manufacturing a pneumatic tire of the present invention includes a step of laminating another tire member on the inner liner of the pneumatic tire and molding a green tire,
Vulcanizing the green tire,
It is preferable to include

  According to the method for manufacturing a pneumatic tire of the present invention, the adhesiveness between adjacent rubber members is high, and the other tire members are laminated on the inner liner of the above-described pneumatic tire. The adhesive force between the inner liner and the inner liner is high, and the peeling of the inner liner from the other tire member can be suppressed both during molding of the raw tire and after running the tire. The green tire forming step is not particularly limited, except that another tire member is laminated on the above-described inner liner of the pneumatic tire, and can be performed in the same manner as a normal green tire. In the pneumatic tire manufacturing method of the present invention, a green tire may be formed by laminating other tire members on the above-described inner liner laminated with a rubber-like elastic layer.

  The shape of the green tire can be appropriately selected according to the shape of the pneumatic tire to be a product.

  For the adhesive layer of the inner liner of the pneumatic tire, as described above, since a polystyrene-based thermoplastic elastomer is used, the tackiness of the adhesive layer is not too high, and the workability in the molding process of the green tire is high. Further, since the adhesive layer is irradiated with active energy rays, the flow of the adhesive layer in the vulcanization step is suppressed, and the workability in the vulcanization step is high.

  The vulcanizing step of the raw tire may be performed at a temperature at which the raw tire is vulcanized, and the vulcanization temperature of a normal raw tire can be employed. Further, the shape of the mold used for vulcanization can be appropriately selected according to the shape of the pneumatic tire to be a product.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
<Preparation of inner liner>
Ethylene-vinyl alcohol copolymer (EVOH) [Kuraray “E105”], polyurethane-based thermoplastic elastomer (TPU) [Kuraray “Kuramilon 3190”], and polystyrene-based thermoplastic elastomer (TPS) ) [Epofriend AT501 manufactured by Daicel Co., Ltd., styrene-butadiene-styrene block copolymer (SBS), styrene content = 40% by mass], and co-extrusion using an extruder. The outermost layer is a TPS layer (adhesive layer), the inner side of the adhesive layer is a TPU layer (elastic layer), and a 21 layer in which a TPU layer (elastic layer) and an EVOH layer (gas barrier layer) are alternately repeated. Inner liner having a structure (TPS layer / TPU layer / EVOH layer / TPU layer /.../ EVOH layer / TPU layer / TPS layer, TPS Two layers, TPU layer 10 layers, to prepare a EVOH layer 9 layers). The molding conditions for coextrusion are as follows. In addition, the film forming property at the time of co-extrusion was evaluated.
The thickness of the TPS layer (each of the two layers) was 5 μm, the thickness of the EVOH layer (each of the nine layers) was 0.5 μm, and the thickness of the TPU layer (each of the two layers) adjacent to the TPS layer was 10 μm. 0.8 μm, and the thickness of the other TPU layers (each of the eight layers) was 4.2 μm.

-Extruder specifications for each raw material-
TPU: 25 mmφ extruder “P25-18AC” [manufactured by Osaka Seiki Co., Ltd.]
EVOH: 20 mmφ extruder Laboratory machine ME type “CO-EXT” [manufactured by Toyo Seiki Co., Ltd.]
TPS: 32 mmφ extruder GF-32-A [Plastic Engineering Laboratory Co., Ltd.]
Extrusion temperature of each raw material: All 220 ° C
T-die specification: 300 mm width coat hanger die [Plastic Engineering Laboratory Co., Ltd.]
Cooling roll temperature: 50 ° C
Pickup speed: 4m / min

  An electron beam having an irradiation dose of 200 kGy was applied to the inner liner obtained as described above at an acceleration voltage of 200 kV using an electron beam accelerator [Curetron EB200-100 manufactured by Nissin High Voltage Co., Ltd.]. Irradiation gave a crosslinked inner liner.

<Production and evaluation of pneumatic tires>
On the forming drum, the inner liner produced as described above is wound, a carcass is stuck thereon, and another tire member is stuck to form a green tire, and the raw tire is vulcanized. A pneumatic tire having the structure shown in FIG. 2 and having a size of 195 / 65R15 was manufactured.

In addition, the coating rubber of the carcass as a part of the carcass adjacent to the inner liner includes natural rubber of 50 parts by mass, SBR [manufactured by JSR Corporation, SBR1712, and 100 parts by mass of the rubber component with 37.times. GPF-grade carbon black (N-660) [manufactured by Asahi Carbon Co., Ltd., 50S], 40 parts by mass, and a softening agent [TOP, manufactured by Daihachi Chemical Industry Co., Ltd.) with respect to 68.75 parts by mass. ] 55 parts by mass, an antioxidant [Nocrac224-S, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] 1.0 parts by mass, stearic acid [Asahi Denka Kogyo Co., Ltd.] 1.5 parts by mass, vulcanization accelerator 1 [Accel M, manufactured by Kawaguchi Chemical Industry Co., Ltd.] 0.5 part by mass, vulcanization accelerator 2 [Accel CZ, manufactured by Kawaguchi Chemical Industry Co., Ltd.] 1 part by mass, zinc oxide [manufactured by Hitec Co., Ltd.] 5 parts by mass , Sulfur [Karuizawa refinery] 3 quality Part was used a rubber composition prepared by blending.
Further, the cross section of the circumferential end of the inner liner was perpendicular to the circumferential direction, and the overlapping width of the ends was 15 mm.

  The adhesion between the inner liner and the bladder at the time of vulcanization was evaluated, and the case where it was difficult to adhere to the bladder was evaluated as "good", and the case where it was difficult to peel off due to the adhesion to the bladder was evaluated as "bad". Table 1 shows the results.

  Furthermore, the number of air between the inner liner and the carcass after the vulcanization was evaluated, and “very good” when the number of air was very small, “good” when the number of air was small, and “bad” when the number of air was large. " Table 1 shows the results.

  From the obtained tire, the inner liner and the carcass were cut out, and the peeling resistance between the inner liner and the carcass and the peeling resistance between the TPS layer (adhesive layer) and the TPU layer (elastic layer) in the inner liner were determined as follows. The method was evaluated. Table 1 shows the results.

(1) Peeling resistance between inner liner and carcass, peeling resistance between TPS layer (adhesive layer) and TPU layer (elastic layer) in inner liner According to JIS K 6854, at a pulling speed of 50 mm / min. The peel resistance between the layers was measured by a T-type peel test.

(Examples 2 to 8, Comparative Examples 2 to 3)
An inner liner was prepared in the same manner as in Example 1 except that the materials shown in Table 1 were used as the raw materials for the adhesive layer, and the irradiation dose of the electron beam was changed as shown in Table 1. Was used to produce a pneumatic tire. The same evaluation as in Example 1 was performed on the obtained pneumatic tire.
In Comparative Example 3, a polyurethane thermoplastic elastomer (TPU) was used for the adhesive layer.

(Comparative Example 1)
Except that the adhesive layer is not provided, the outermost layers are TPU layers (elastic layers) in the same manner as in Example 1, and the TPU layers (elastic layers) and the EVOH layers (gas barrier layers) are alternately repeated. An inner liner having a layer structure (TPU layer / EVOH layer / TPU layer /.../ EVOH layer / TPU layer, 10 TPU layers, 9 EVOH layers) was produced. Furthermore, 75 parts by mass of epoxidized natural rubber 1 (trade name: ENR25, manufactured by RRIM, epoxidation degree (epoxidation ratio) 25%) and epoxidized natural rubber 2 (trade name: ENR50) And 25 parts by mass of epoxidation degree (epoxidation ratio) manufactured by RRIM Co., Ltd. to form an adhesive layer having a thickness of 5 μm to obtain an inner liner.
Except for using the obtained inner liner, a pneumatic tire was prepared in the same manner as in Example 1, and the obtained pneumatic tire was evaluated in the same manner as in Example 1.

* 1 TPS1: “Epofriend AT501” manufactured by Daicel Corporation, styrene-butadiene-styrene block copolymer (SBS), styrene content = 40% by mass
* 2 TPS2: “Tuffrene 912” manufactured by Asahi Kasei Chemicals Corporation, styrene-butadiene-styrene block copolymer (SBS), styrene content = 40% by mass.
* 3 TPS3: “Tuffrene A” manufactured by Asahi Kasei Chemicals Corporation, styrene-butadiene-styrene block copolymer (SBS), styrene content = 40% by mass.
* 4 TPS4: “Quintac 3390” manufactured by Zeon Corporation, styrene-isoprene-styrene block copolymer (SIS), styrene content = 48% by mass
* 5 ENR: A mixture of 75 parts by mass of "ENR25" manufactured by RRIM and 25 parts by mass of "ENR50" manufactured by RRIM * 6 TPU: "Kuramilon 3190" manufactured by Kuraray Co., Ltd., polyurethane thermoplastic elastomer (TPU)

  From Table 1, it can be seen that the inner liner manufactured by the method of the present invention has high peeling resistance between the TPS layer (adhesive layer) and TPU layer (elastic layer), so that delamination hardly occurs. It can be seen that the peeling resistance from the carcass is large and the adhesion to the adjacent member (carcass) is high.

(Examples 9 to 13)
As raw materials for the adhesive layer, polyurethane thermoplastic elastomer (TPU) [* 6, "Kuramilon 3190" manufactured by Kuraray Co., Ltd.], and polystyrene-based thermoplastic elastomer (TPS) [* 1, "Epofriend" manufactured by Daicel Co., Ltd. AT501 ", styrene-butadiene-styrene block copolymer (SBS), styrene content = 40% by mass], and the blending ratio thereof was changed as shown in Table 2, except that it was the same as in Example 1. Then, an inner liner was produced, and a pneumatic tire was produced using the inner liner. The same evaluation as in Example 1 was performed on the obtained pneumatic tire. Table 2 shows the results.

  From Table 2, it can be seen that the adhesive layer contains a polystyrene-based thermoplastic elastomer and a thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer in a mass ratio in the range of 25:75 to 75:25. It can be seen that the adhesiveness between the two is greatly improved.

(Comparative Examples 4 to 6)
Except that the inclination angle from the tire width direction of the cut surface of the circumferential end portion of the inner liner is set as shown in Table 3, and the overlapping width between the end portions of the inner liner is set as shown in Table 3 A pneumatic tire was produced in the same manner as in Example 1.
Here, after the green tire was molded, the inner surface of the green tire was observed, and it was confirmed whether or not the overlapping portion (joint portion) of the end of the inner liner had peeled off. Moreover, the peeling resistance between the adhesive layer and the TPU layer (elastic layer) was measured in the same manner as in Example 1. Table 3 shows the results.

(Comparative Examples 7 to 12 and Examples 14 to 18)
The inner liner is cut into so-called “jagged” so that the end portion has a peak portion and a valley portion alternately, and as shown in FIG. 3, a ridge portion at one end portion of the inner liner and a valley portion at the other end portion are formed. A pneumatic tire was manufactured in the same manner as in Example 1 except that the tires were arranged so as to be close to each other. In addition, the overlapping width of the ends of the inner liner, the angle of the peak of the peak, and the angle of the bottom of the trough are as shown in Table 3.
Also in this case, similarly to Comparative Examples 4 to 6, after molding the green tire, the inner surface of the raw tire was observed, and it was confirmed whether or not the overlapping portion (joint portion) at the end of the inner liner was peeled off. Moreover, the peeling resistance between the adhesive layer and the TPU layer (elastic layer) was measured in the same manner as in Example 1. Table 3 shows the results.

(2) Drum Durability The pneumatic tires obtained in Example 1, Examples 14 to 18 and Comparative Examples 4 to 12 were mounted on a 6J-15 rim, and adjusted to an internal pressure of 100 kPa lower than the specified internal pressure. A durability test was performed using a drum tester having a drum with a smooth surface. In the test, the tires were pressed against the drum and a load of 615 kgf was applied, and the tire (sidewall portion) was run (rotated) at the same predetermined speed on the drum until a failure (crack) occurred in the tire (sidewall). It is an internal pressure long ground ram test. In addition, the test was stopped at a running distance of 10,000 km, the inner surface of the tire was observed, and the degree of peeling of the overlapping portion (joint portion) at the end of the inner liner was confirmed. The case where there was no peeling was regarded as good (◎), the case where there was some peeling, but the case where practical use was possible (、), and the case where there was peeling and the case where practical use was not possible (×). Table 2 shows the results.

  From Table 3, it can be seen that (1) the cut surface of the end of the inner liner is parallel to the tire width direction, and the overlapping width of the ends is in the range of 5 mm to 20 mm, or (2) the inner Crests and valleys are alternately formed at the end of the liner, the angle of the peak of the crest and the angle of the bottom of the valley are in the range of 45 ° to 120 °, and the overlap width between the ends is 1 mm. It can be seen that, by setting the range to １３13 mm, the joint portion at the end of the inner liner can be prevented from being peeled off after the molding of the green tire and after the drum test.

(Examples 19 to 21)
A composite was prepared in the same manner as in Example 1 except that a rubber-like elastic layer having a thickness shown in Table 4 was attached to the outer side of the inner liner in the tire radial direction, and a carcass was attached on the composite. Thus, a pneumatic tire having an inner liner having the structure shown in FIG. 4 was manufactured.
Moreover, the peeling resistance between the adhesive layer and the TPU layer (elastic layer) was measured in the same manner as in Example 1. Table 4 shows the results.

  The rubber-like elastic layer has 50 parts by mass of natural rubber and 68.75 parts by mass of SBR [SBR1712 manufactured by JSR Corporation, including 37.5 parts by mass of the extension oil with respect to 100 parts by mass of the rubber component]. On the other hand, 40 parts by mass of GPF grade carbon black (N-660) [manufactured by Asahi Carbon Co., Ltd., 50S], 55 parts by mass of a softening agent [TOP, manufactured by Daihachi Chemical Industry Co., Ltd.], an antioxidant [Nocrac224- S, Ouchi Shinko Chemical Industry Co., Ltd.] 1.0 parts by mass, stearic acid [Asahi Denka Kogyo Co., Ltd.] 1.5 parts by mass, vulcanization accelerator 1 [Accel M, Kawaguchi Chemical Co., Ltd.] 0.5 parts by mass, vulcanization accelerator 2 [Accel CZ, manufactured by Kawaguchi Chemical Industry Co., Ltd.] 1 part by mass, zinc oxide [manufactured by Hitec Corporation] 5 parts by mass, sulfur [manufactured by Karuizawa Refinery] 3 parts by mass Was used.

(Example 22)
A pneumatic tire having an end portion of the inner liner having a structure shown in FIG. 5 was produced in the same manner as in Example 1 except that a rubber-like elastic layer was separately attached to the inner liner. The composition of the rubber-like elastic layer was the same as in Examples 19 to 21.
Moreover, the peeling resistance between the adhesive layer and the TPU layer (elastic layer) was measured in the same manner as in Example 1. Table 4 shows the results.

(3) Drum Durability The pneumatic tire obtained in each of Examples 1 and 19 to 22 was pressed on a drum under the conditions of an air pressure of 160 kPa (relative pressure), a tire load of 4.0 kN, and a speed of 80 km / h, and a speed of 1000 km. After running, the inner surface of the tire is observed to check for cracks in the inner liner, and the overlapping portion (joint portion) of the end of the inner liner (or the composite of the inner liner and the rubber-like elastic layer) ) Was evaluated (peeled area occupied on the bonding surface). Table 4 shows the results.

  From Table 4, it can be seen that the provision of the rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm can suppress peeling of the joint at the end of the inner liner after the drum test.

  The inner liner manufactured by the method of the present invention can be used for a pneumatic tire. Further, the pneumatic tire manufactured by the method of the present invention can be used as a tire for various vehicles.

100: inner liner, 10: film layer, 11: gas barrier layer, 12: elastic layer, 20: adhesive layer, 1: bead portion, 2: sidewall portion, 3: tread portion, 4: carcass, 5: belt, 6 : inner liner, 7: bead core, 100a: one end portion of the inner liner, 100b: the other end portion of the inner liner, _{T a:} the crest of one end portion of the inner liner, _{B a:} the valley portions of the one end portion of the inner liner, T _b: the mountain portion of the other end portion of the inner liner, B _b: the troughs of the other end portion of the inner liner, T _alpha: angle of the apex of the mountain portion of the one end portion of the inner liner, B _alpha: the innerliner angle valley of the valley of one end, T _beta: angle of the apex of the mountain portion of the other end portion of the inner liner, B _beta: valley valley other end portion of the inner liner Angle, D: the innerliner the tire circumferential direction of the end portion overlapping width between 8: rubbery elastomer layer, H: thickness of the rubber-like elastic body layer, F: expansion force of the tires, M: Moment

Claims (12)

A method for manufacturing an inner liner of a pneumatic tire comprising a film layer and an adhesive layer disposed on at least one surface of the film layer,
The film layer has a gas barrier layer and an elastic layer disposed on at least one surface of the gas barrier layer,
The gas barrier layer contains at least a thermoplastic resin,
The elastic layer contains at least a polyurethane-based thermoplastic elastomer,
The adhesive layer includes a polystyrene-based thermoplastic elastomer and a thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer ,
The mass ratio of the polystyrene-based thermoplastic elastomer contained in the adhesive layer and the thermoplastic elastomer other than the polystyrene-based thermoplastic elastomer is in a range of 25:75 to 75:25,
A method for producing an inner liner for a pneumatic tire, comprising irradiating an active energy ray after laminating the film layer and the adhesive layer by co-extrusion.   The method for manufacturing an inner liner for a pneumatic tire according to claim 1, wherein the adhesive layer is provided on both surfaces of the film layer. The method for producing an inner liner for a pneumatic tire according to claim 1 or 2 , wherein the polystyrene-based thermoplastic elastomer contained in the adhesive layer has a styrene content of 40% by mass to 55% by mass. The film layer, the gas barrier layer and the elastic layer are alternately laminated,
The method for manufacturing an inner liner for a pneumatic tire according to any one of claims 1 to 3 , wherein the elastic layer is located on both outermost surfaces of the film layer. The method for manufacturing an inner liner for a pneumatic tire according to any one of claims 1 to 4 , wherein the film layer has a total number of layers of the gas barrier layer and the elastic layer of 7 or more. The method for manufacturing an inner liner for a pneumatic tire according to any one of claims 1 to 5 , wherein at least one surface of the inner liner has a rubber-like elasticity having a thickness of 0.1 mm to 1.0 mm. A method for producing an inner liner of a pneumatic tire, comprising laminating body layers. A method for manufacturing a pneumatic tire, comprising using an inner liner manufactured by the method for manufacturing an inner liner for a pneumatic tire according to any one of claims 1 to 6 . It is a manufacturing method of the pneumatic tire according to claim 7 ,
On the tire inner surface, the inner liner extends in the tire circumferential direction, and the ends of the inner liner in the tire circumferential direction are arranged so as to overlap in the tire radial direction,
Both ends of the inner liner in the tire circumferential direction are parallel to the tire width direction,
A method of manufacturing a pneumatic tire, wherein an overlap width between ends of the inner liner in a tire circumferential direction is in a range of 5 mm to 20 mm. It is a manufacturing method of the pneumatic tire according to claim 7 or 8 ,
On the tire inner surface, the inner liner extends in the tire circumferential direction, and the ends of the inner liner in the tire circumferential direction are arranged so as to overlap in the tire radial direction,
The end of the inner liner has peaks and valleys alternately,
The end of the inner liner, the angle of the peak of the peak, the angle of the bottom of the valley, the range of 45 ° ~ 120 °,
A method of manufacturing a pneumatic tire, wherein an overlap width between ends of the inner liner in a tire circumferential direction is in a range of 1 mm to 13 mm. The air according to any one of claims 7 to 9 , wherein the pneumatic tire includes a rubber-like elastic layer having a thickness of 0.1 mm to 1.0 mm outside a radial direction of the inner liner. Method for manufacturing tires containing steel. The method for manufacturing a pneumatic tire according to claim 10 , wherein the thickness of the rubber-like elastic layer is 0.2 mm to 0.6 mm. A step of laminating another tire member on an inner liner of a pneumatic tire manufactured by the method for manufacturing an inner liner of a pneumatic tire according to any one of claims 1 to 6 , and molding a green tire. When,
Vulcanizing the green tire,
The method for manufacturing a pneumatic tire according to any one of claims 7 to 11 , comprising:

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