JP5575080B2 - Inner liner and method for manufacturing pneumatic tire - Google Patents

Description

  The present invention relates to a strip for an inner liner used in a pneumatic tire, a method for producing the strip, and a method for producing a pneumatic tire using the strip.

  In recent years, tires have been made lighter due to the strong social demand for low fuel consumption of vehicles, and among the tire members, the amount of air leakage from the inside of the pneumatic tire to the outside is arranged inside the tire. In the inner liner having a function of reducing the weight, weight reduction and the like have been performed.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-291256) includes natural rubber and / or synthetic rubber as a pneumatic tire capable of simultaneously suppressing air pressure reduction, improving durability, and improving fuel efficiency. A pneumatic tire is proposed in which a rubber composition for an inner liner containing at least 15 to 30 parts by mass of an ethylene-vinyl alcohol copolymer is used for an inner liner layer with respect to 100 parts by mass of a rubber component. Has been. However, in the technique of Patent Document 1, the thickness of the rubber sheet using the rubber composition is 1 mm, and there is room for improvement from the viewpoint of reducing the weight of the tire.

  In Patent Document 2 (Japanese Patent Application Laid-Open No. 9-165469), an inner liner layer is formed using nylon having a low air permeability, and adhesion to a tire inner surface or a carcass layer, which is a rubber composition, is improved. Proposed. However, in the technique of Patent Document 2, in order to form a nylon film layer, after the nylon film is RFL-treated, it is necessary to bond a rubber paste made of a rubber composition, which causes a problem that the process becomes complicated. . Furthermore, in the vulcanization process, the bladder is expanded from the inside of the unvulcanized tire, but the nylon of the inner liner layer comes into contact with the bladder in a heated state, and the inner liner adheres to and adheres to the bladder and breaks. There's a problem.

  In order to reduce the weight of the tire, a film made of a material containing a thermoplastic resin has been proposed. However, if a tire is manufactured using a thin inner liner made of a thermoplastic resin, the pressure in the vulcanization process is partially reduced so that the finished gauge of the inner liner of the tire product becomes thinner than the design. The inner liner with a thin finish has the phenomenon that the carcass cord appears at that point (open thread), giving the user the impression that the inner appearance is poor. In addition, if the inner liner is thin, the gas barrier property is partially degraded. Therefore, the tire internal pressure decreases, and in the worst case, the tire may burst.

  The inner liner is subjected to a large shear strain in the vicinity of the shoulder when the tire is running. When a material containing a thermoplastic resin is used as the inner liner, there is a problem that due to this shear strain, peeling is likely to occur at the adhesive interface between the inner liner and the carcass ply, resulting in tire air leakage.

  Patent Document 3 (International Publication No. 2008/029781) manufactures a tire with a strip of a film laminate obtained by blending a thermoplastic resin and a thermoplastic elastomer. By using a laminate, gas barrier properties and adhesiveness can be improved, and bonding between ribbon-like strips is possible. However, with this technique, the gauge at the unvulcanized green cover of the film laminate is constant, and if the gauge is thinned, the tire finish after vulcanization at the buttress portion or the like may be thinned.

  Patent Document 4 (Japanese Patent Laid-Open No. 2009-220460) discloses a cross-sectional shape of a die slit by extruding a thermoplastic elastomer composition in which a thermoplastic resin is a sea component and rubber is an island component from an extrusion die into a sheet shape. In addition to having a thick extruded portion between the center portion of the slit and both ends of the slit, the ratio (%) of the thickness increase Δt to the thickness change portion length Δl in the slit length direction is 0.01 to 10%. A method for producing an inner liner material that is extruded using the above-described extrusion die is disclosed. Such a configuration is intended to have a large air leakage prevention effect and is difficult to peel off.

  However, it is difficult to change the dimensions of the extrusion die, and the tire size to be manufactured is limited. Even if several types of extrusion dies are prepared, it takes time to change the size when changing the size and the productivity is lowered.

  Patent Document 5 (Japanese Patent Laid-Open No. 2000-254980) discloses that a rubber member is formed with a contour shape close to a desired finished cross-sectional shape by sequentially winding a ribbon-like unvulcanized rubber strip on a cylindrical drum. Disclosure.

  Conventionally, inner liners used in pneumatic tires are generally continuously extruded from rubber extruders with a predetermined finished cross-sectional shape, and the finished cross-sectional shape is determined by a base provided at the head of the rubber extruder. Has been. In the conventional method of extruding with a finished cross-sectional shape, since the cross-sectional size of the rubber member is large, a large rubber extruder is required, and as a result, the production line cannot be reduced in size. In addition, many types of bases must be prepared according to the type of tire, etc., and every time the type of tire to be manufactured is changed, the base must be replaced or adjusted, etc. This is to solve the above problems.

  However, when the tire member is formed of a ribbon-like rubber strip, there is a problem in processability due to the adhesiveness between the rubber compositions, and the shape of the rubber member formed of the rubber strip loses its shape during storage. There was a problem that caused.

  Patent Document 6 (Japanese Patent Laid-Open No. 2010-058437) discloses a method in which a molten resin is extruded from a die into a sheet shape, and the extruded resin sheet is sandwiched by a mold roller and a nip roller having a convex shape formed on at least one side. Is disclosed, and a sheet is formed by forming a cut groove and solidifying by cooling.

  Patent Document 7 (Japanese Patent Laid-Open No. 9-19987) discloses a laminate for improving the adhesion between the inner liner layer and the rubber layer. By providing an adhesive layer on both sides of the inner liner layer, the adhesive layers come into contact with each other at the overlapping portion of the inner liner layer, and are firmly bonded by heating, thereby improving air pressure retention. . However, the adhesive layer for overlapping the inner liner layer comes into contact with the bladder in a heated state in the vulcanization process, and there is a problem of sticking to the bladder.

JP 2007-291256 A JP-A-9-165469 International Publication No. 2008/029781 JP 2009-220460 A JP 2000-254980 A JP 2010-058437 A JP-A-9-19987

  The present invention provides a ribbon-like strip used for an inner liner and a method for producing the same. The strip generally has a flat rectangular cross-sectional shape. Therefore, when a sheet having a wider width is produced by overlapping ribbon-shaped strips having a predetermined width, the overlapping portion at both end portions of the strip becomes thick, and irregularities are formed on the surface of the finished sheet. Accordingly, a first object of the present invention is to make the thickness of the inner liner uniform by forming the ears on a ribbon-like strip.

  A second object of the present invention is to reduce rolling resistance by reducing the weight by using a strip of a thermoplastic elastomer composition containing a thermoplastic elastomer and a styrene-maleic anhydride copolymer, and further to a bladder during the vulcanization process. It is to prevent the inner liner from being broken or deformed by the heat and pressure, and to eliminate the occurrence of scratches on the surface and residual air inside.

  The third object of the present invention is to improve the adhesiveness between the inner liner and the carcass ply by using the strip of the thermoplastic elastomer composition, and to reduce the crack growth due to repeated bending deformation during tire running. is there.

  The present invention relates to a strip of a thermoplastic elastomer composition for forming a tire inner liner having a shape close to a finished cross-sectional shape by being spirally wound on a cylindrical drum, the strip comprising styrene-isobutylene. -A thermoplastic elastomer composition containing 60-99.9% by mass of a styrene triblock copolymer (hereinafter also referred to as "SIBS") and 0.5-40% by mass of a styrene-maleic anhydride copolymer. At least one of the first layer, a styrene-isoprene-styrene triblock copolymer (hereinafter also referred to as “SIS”), and a styrene-isobutylene-styrene triblock copolymer (hereinafter also referred to as “SIB”). A laminate of a second layer made of a thermoplastic elastomer composition containing A strip main body and ears disposed on both sides thereof, and the thickness (T1) of the strip body is 0.05 mm to 1.0 mm, and the thickness (T2) of the ear portion is the thickness of the strip body. The present invention relates to a strip for forming an inner liner that is thinner than the thickness (T1) and has a width (W2) of an ear portion of 0.5 mm to 5.0 mm.

  The styrene-isobutylene-styrene triblock copolymer preferably has a weight average molecular weight of 50,000 to 400,000 and a styrene component content of 10 to 30% by mass. The styrene-maleic anhydride copolymer has a styrene component / maleic anhydride component molar ratio of 50/50 to 90/10, a weight average molecular weight of 4,000 to 20,000, and further anhydrous. It is desirable to include a styrene-maleic anhydride copolymer-based resin having a maleic acid component acid value of 50 to 600.

  Further, the styrene-maleic anhydride copolymer is a styrene-maleic anhydride copolymer having a monoester group and a monocarboxylic acid group obtained by esterifying the styrene-maleic anhydride copolymer base resin. Combined ester resins can be included.

  In addition, the styrene-maleic anhydride copolymer may include an aqueous styrene-maleic anhydride copolymer ammonium salt solution in which the styrene-maleic anhydride copolymer base resin is dissolved in an ammonium salt.

  The width (W0) of the strip of the present invention is preferably 5 mm to 40 mm, and the thickness (T2) of the ear portion of the strip is preferably 0.02 mm to 0.5 mm. The thickness of the first layer is preferably 0.05 mm to 0.6 mm, and the thickness of the second layer is preferably 0.01 mm to 0.3 mm.

The present invention is a method for producing a strip comprising the thermoplastic elastomer composition,
(A) an extrusion step of extruding the thermoplastic elastomer composition to form a sheet having a horizontally long rectangular cross-sectional shape by an extrusion apparatus including an extruder body and an extrusion head;
(B) The sheet is passed through a pair of mold rollers, the shape of the mold roller is transferred to the sheet, and a strip forming step provided with an ear at the end of the strip;
(C) a peeling step of peeling the strip from the mold roller;
The present invention relates to a method for manufacturing a strip including

  Further, the present invention provides a pneumatic tire characterized in that the strip is spirally wound on a cylindrical drum to form an inner liner, and the inner liner is disposed on the inner surface of the green tire and then vulcanized. Regarding the method.

  In the present invention, the thermoplastic elastomer composition is used, and the strip having the ears at both ends is used as the inner liner. Therefore, it is possible to design an unvulcanized raw cover whose thickness is adjusted according to the arrangement portion of the tire. For example, since only the buttress part can be designed to be thick, gas barrier properties and tire durability can be improved. Moreover, since it is a ribbon-shaped strip, it can be applied regardless of the size of the tire. In particular, the first layer made of a thermoplastic elastomer composition containing SIBS and a styrene-maleic anhydride copolymer and a laminated body bonded to a second layer containing at least one of SIS and SIB have the ear portion. By adopting the strip, it is a manufacturing method in which the thickness on the tire circumference is uniform, and thus there is an advantage that radial force variation (RFV) can be improved.

  And the pneumatic tire which used this strip for the inner liner maintains air barrier property, can make the whole thickness thin, can achieve weight reduction, and can aim at reduction of rolling resistance. Furthermore, the adhesiveness with the adjacent carcass ply can be improved and the flex crack growth can be reduced.

It is a schematic sectional drawing of the right half of the pneumatic tire of this invention. 1 is a schematic view of an apparatus for producing the strip of the present invention. It is sectional drawing which shows the space | interval of a type | mold roll and a nip roll in the manufacturing apparatus shown in FIG. (A)-(d) is a schematic sectional drawing of the strip of this invention. It is the schematic which shows the method of manufacturing an inner liner using the strip of this invention. It is the schematic which shows the method of manufacturing an inner liner using the conventional strip. is there.

<Tire structure>
The present invention relates to a strip for an inner liner disposed inside a pneumatic tire, a method for manufacturing the strip, and a method for manufacturing a pneumatic tire including the strip. The inner liner is manufactured by spirally winding a ribbon-like strip having ears at both ends on a cylindrical drum. Here, the ribbon-like strip is extruded in a state close to the finished cross-sectional shape.

  The strip is formed of a laminate of at least two layers. The first layer is made of styrene-isobutylene-styrene triblock copolymer (SIBS), and the second layer contains styrene-isoprene-styrene triblock copolymer (SIS) or styrene-isobutylene block copolymer (SIB). . Here, the first layer preferably has a thickness of 0.05 mm to 0.6 mm, and the second layer preferably has a thickness of 0.01 mm to 0.3 mm. The second layer is disposed in contact with the rubber layer of the carcass ply.

  An embodiment of a pneumatic tire manufactured by the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of the right half of a pneumatic tire. In the figure, a pneumatic tire 1 has a tread portion 2 and sidewall portions 3 and bead portions 4 so as to form a toroid shape from both ends of the tread portion. Further, a bead core 5 is embedded in the bead portion 4. In addition, a carcass ply 6 provided from one bead portion 4 to the other bead portion, with both ends wound around the bead core 5 and locked, and at least two sheets on the outer side of the crown portion of the carcass ply 6 A belt layer 7 made of a ply is arranged.

  The belt layer 7 usually intersects two plies made of steel cords or cords such as aramid fibers with respect to the tire circumferential direction so that the cords are usually at an angle of 5 to 30 °. Are arranged as follows. Note that a topping rubber layer can be provided on both outer sides of the belt layer to reduce peeling at both ends of the belt layer. In the carcass ply, organic fiber cords such as polyester, nylon, and aramid are arranged at approximately 90 ° in the tire circumferential direction. In the region surrounded by the carcass ply and the folded portion, the bead core 5 extends from the upper end to the sidewall direction. An extending bead apex 8 is arranged. Further, an inner liner 9 extending from one bead portion 4 to the other bead portion 4 is disposed inside the carcass ply 6 in the tire radial direction.

<Strip>
4A to 4D show cross-sectional views of the embodiment of the strip 10. The strip 10 has a thickness (T1) of the strip body 10A of 0.05 mm to 1.0 mm.

  When the thickness (T1) of the strip body 10A is less than 0.05 mm, extrusion molding becomes difficult, and the number of times is unnecessarily increased to form an inner liner having a predetermined thickness, and when the thickness exceeds 1.0 mm. It will not be possible to reduce the bending durability and weight of the inner liner. The thickness (T1) of the strip is preferably in the range of 0.1 mm to 0.6 mm. And the width | variety (W0) of the whole strip is adjusted in the range of 5 mm-40 mm, Preferably it is the range of 10-30 mm.

  The thickness (T2) of the ear portion 10B formed on both sides of the strip body 10A is formed to be thinner than the thickness (T1) of the strip body, and is preferably in the range of 0.02 mm to 0.5 mm. The range is 0.02 mm to 0.3 mm. If the ear thickness (T2) is less than 0.02 mm, the dimensional accuracy of the extrusion may decrease, whereas if the ear thickness (T2) is greater than 0.5 mm, the adjacent strip may The unevenness of the surface to be formed may become large. Here, the thickness (T2) of the ear portion is defined as an average thickness in the width direction when changing in the width direction of the strip.

  And the width (W2) of the ear | edge part 10B has the preferable range of 0.5 mm-5.0 mm in order to smooth the unevenness | corrugation formed on the surface wound on a drum, and the value of (W2 * 2) is , (W0 × 0.5) or less. When the width (W2) of the ear portion is out of the range of 0.5 mm to 5.0 mm, the thickness dimension of the cross section of the inner liner formed by joining the strips may be nonuniform. Here, the strip ears 10B are preferably symmetrical at the left and right ends of the strip body, but can also be asymmetric.

  In FIG. 4A, the cross section of the strip has a substantially parallelogram. The left ear portion 10B has a shape in which the thickness gradually decreases in the downward direction, and the right ear portion 10B has a shape in which the thickness gradually decreases in the upward direction.

  In FIG. 4B, an ear portion 10B having a thickness gradually reduced toward the lower surface of the strip is formed in the left end direction and the right end direction of the strip body 10A. In this strip shape, when the strips are joined on the drum, a step is formed at the end where the adjacent strips are joined to each other, but an inner liner sheet with a reduced surface irregularity shape can be obtained. .

  In FIG. 4C, the left ear is formed with a certain thickness on the lower surface, and the right ear is formed with a certain thickness on the upper surface. By adopting such a shape, when the strip is rewound on the drum to form the inner liner, the adjacent strip ears relieve the step formed at the end of the strip and can be joined with small unevenness. The strip body 10A has a rectangular shape with a horizontally long flat shape whose thickness (T1) is constant in the length direction.

  In FIG. 4 (d), a step is formed at the left end and the right end of the strip body 10A to form an ear portion 10b having a reduced thickness, and the strip has a constant thickness on the lower surface. In this case, when the strips are joined on the drum, a step is formed at the end of the adjacent strip, but the unevenness can be reduced.

  By forming the strip of the present invention into the above-mentioned shape, when the strip is rewound on the drum to form the inner liner, the adjacent strip ears are properly fitted to form a joint with no thickness unevenness. it can. Note that the thickness (T1) of the strip body 10A has a rectangular shape that is horizontally long and flat in the length direction. In addition, the ear | edge part of this invention can employ | adopt not only these shapes but various modifications.

<Laminate>
In the present invention, the inner liner is manufactured by winding a ribbon-like strip on a drum, and the strip is a laminate. Here, the laminate is a first layer of a thermoplastic elastomer containing a styrene-isobutylene-styrene triblock copolymer (SIBS) and a styrene-maleic anhydride copolymer, a styrene-isoprene-styrene triblock copolymer (SIS). ) And a second layer containing at least one of styrene-isobutylene-styrene triblock copolymer (SIBS). By manufacturing a strip with ears on both sides in the width direction of such a laminate and using it as an inner liner, the surface irregularities can be made smaller and smoother, and the air pockets caused by the large irregularities can be conventional. Can solve the problem.

<First layer>
The first layer is composed of 60 to 99.5% by mass of styrene-isobutylene-styrene triblock copolymer (SIBS) and styrene-maleic anhydride copolymer (hereinafter also referred to as “SMA”) 0.5 to 0.5. It consists of a thermoplastic elastomer composition containing 40% by mass.

  By blending SMA with SIBS, the thermoplastic elastomer composition can improve vulcanization adhesion with rubber while maintaining air barrier properties. Since SIBS is derived from its isobutylene block, the polymer film made of SIBS has excellent air permeation resistance. Therefore, when a thermoplastic elastomer made of SIBS is used for the inner liner, a pneumatic tire having excellent air permeation resistance can be obtained.

  Further, SIBS has excellent durability because its molecular structure other than aromatic is completely saturated, thereby preventing deterioration and hardening. Therefore, when a thermoplastic elastomer film made of SIBS is used for the inner liner, a pneumatic tire having excellent durability can be obtained.

  When a pneumatic tire is manufactured by applying a thermoplastic elastomer film made of SIBS to the inner liner, air permeation resistance can be secured. Therefore, it is not necessary to use a halogenated rubber having a high specific gravity such as a halogenated butyl rubber which has been used for imparting conventional air permeation resistance, and the amount used can be reduced even when used. As a result, the weight of the tire can be reduced, and the effect of improving fuel consumption can be obtained.

  The molecular weight of SIBS is not particularly limited, but the weight average molecular weight by GPC measurement is preferably 50,000 to 400,000 from the viewpoints of fluidity, molding process, rubber elasticity and the like. If the weight average molecular weight is less than 50,000, the tensile strength and tensile elongation may be lowered, and if it exceeds 400,000, the extrusion processability may be deteriorated. From the viewpoint of improving air permeation resistance and durability, SIBS has a styrene component content in SIBS of 10 to 30% by mass, preferably 14 to 23% by mass.

  The SIBS is a copolymer in which the degree of polymerization of each block is about 10,000 to 150,000 for isobutylene from the viewpoint of rubber elasticity and handling (becomes liquid when the degree of polymerization is less than 10,000), and styrene. Then, it is preferable that it is about 5,000-30,000.

  SIBS can be obtained by a living cationic polymerization method of a general vinyl compound. For example, JP-A-62-48704 and JP-A-64-62308 disclose that living cationic polymerization of isobutylene and other vinyl compounds is possible. By using isobutylene and other compounds as vinyl compounds, It is disclosed that a polyisobutylene-based block copolymer can be produced.

  Since SIBS does not have double bonds other than aromatics in the molecule, it is more stable to ultraviolet rays than a polymer having double bonds in the molecule, such as polybutadiene, and therefore has weather resistance. It is good.

<Styrene-maleic anhydride copolymer>
In this specification, the styrene-maleic anhydride copolymer (SMA) means a styrene-maleic anhydride copolymer base resin (hereinafter also referred to as “SMA base resin”), a styrene-maleic anhydride copolymer base resin. Ester resin of a styrene-maleic anhydride copolymer having a monoester group and a monocarboxylic acid group (hereinafter also referred to as SMA ester resin) and a styrene-maleic anhydride copolymer base resin obtained by esterification of Is a concept including an aqueous solution of ammonium salt of styrene-maleic anhydride copolymer dissolved in an ammonium salt (hereinafter also referred to as an aqueous solution of SMA resin ammonium salt).

  Styrene-maleic anhydride copolymer (SMA) is used as a polymer surfactant and a high-functional cross-linking agent in dispersion and emulsification, and has excellent vulcanization adhesion to rubber. Moreover, since the wettability is given to rubber, the adhesive effect is also excellent.

  In the polymer component of the thermoplastic elastomer composition, the SMA content is 0.5 to 40% by mass. When the SMA content is 0.5% by mass or more, an inner liner having excellent adhesiveness with the second layer can be obtained. Moreover, when the SMA content is 40% by mass or less, an inner liner having excellent air permeation resistance and durability can be obtained. As for content of SMA in a polymer component, 2-30 mass% is more preferable.

(Styrene-maleic anhydride copolymer-based resin)
In one embodiment of the present invention, the SMA preferably contains an SMA base resin from the viewpoints of unvulcanized tackiness and post-vulcanized adhesion.

  The SMA base resin preferably has a styrene component / maleic anhydride component molar ratio of 50/50 to 90/10 from the viewpoints of a high softening point and high thermal stability. The SMA base resin preferably has a weight average molecular weight of 4,000 to 20,000 from the viewpoint of adhesion after vulcanization and fluidity. Furthermore, the weight average molecular weight is more preferably 5,000 to 15,000.

  In the SMA base resin, the maleic anhydride component in the styrene-maleic anhydride copolymer preferably has an acid value of 50 to 600 from the viewpoint of unvulcanized adhesiveness. Furthermore, the acid value of the maleic anhydride component is more preferably 95 to 500.

(Ester resin of styrene-maleic anhydride copolymer)
In one embodiment of the present invention, the styrene-maleic anhydride copolymer is obtained by esterifying a styrene-maleic anhydride copolymer-based resin and having a monoester group and a monocarboxylic acid group. It preferably contains an ester resin of maleic anhydride copolymer (hereinafter also referred to as SMA ester resin).

  The SMA ester resin has the property of being excellent in vulcanization adhesion. Therefore, by blending SMA ester resin with SIBS, it is possible to obtain a thermoplastic elastomer composition for an inner liner having excellent vulcanization adhesion with a rubber layer. The SMA ester resin preferably has a styrene component / maleic anhydride component molar ratio of 50/50 to 90/10 from the viewpoint of vulcanization adhesion.

  The SMA ester resin preferably has a weight average molecular weight of 5,000 to 12,000 from the viewpoint of adhesion after vulcanization and fluidity. Furthermore, the weight average molecular weight is more preferably 6,000 to 11,000. In the SMA ester resin, the maleic anhydride component preferably has an acid value of 50 to 400 from the viewpoint of adhesion to unvulcanized rubber. Furthermore, the acid value of the maleic anhydride component is more preferably 95 to 290.

  The SMA ester resin can be produced, for example, by introducing a base resin and alcohol into a reaction vessel and heating and stirring in an inert gas atmosphere.

(Styrene-maleic anhydride copolymer ammonium salt aqueous solution)
In one embodiment of the present invention, the styrene-maleic anhydride copolymer is a styrene-maleic anhydride copolymer aqueous ammonium salt solution (hereinafter also referred to as an SMA ammonium salt aqueous solution) in which an SMA base resin is dissolved in an ammonium salt. It is preferable to contain.

  The SMA ammonium salt aqueous solution has a property of excellent wettability. Therefore, the thermoplastic elastomer composition for inner liners excellent in adhesiveness can be obtained by blending an aqueous SMA ammonium salt solution with SIBS.

  The SMA ammonium salt aqueous solution preferably has a solid content of 10.0 to 45.0% from the viewpoint of adhesion to unvulcanized rubber and molding processability. The aqueous SMA ammonium salt solution preferably has a pH of 8.0 to 9.5 from the viewpoint of tackiness. An aqueous SMA ammonium salt solution causes exothermic reaction when water is added to a reaction vessel, base resin is added with vigorous stirring, and ammonium hydroxide is gradually added. Then, it can manufacture by heating to predetermined temperature and continuing stirring until melt | dissolution is completed.

<Additive of thermoplastic elastomer composition>
The thermoplastic elastomer composition in one embodiment of the present invention includes other reinforcing agents, vulcanizing agents, vulcanization accelerators, various oils, anti-aging agents, softeners, plasticizers, coupling agents, and the like for tires. Or the various compounding agents and additives mix | blended with a general polymer composition can be mix | blended.

<Thickness of the first layer>
The thickness of the first layer made of SIBS is preferably 0.05 to 0.6 mm. When the thickness of the first layer is less than 0.05 mm, the vulcanization of the raw tire in which the laminated body is applied to the inner liner causes the first layer to be broken by the press pressure, and an air leak phenomenon occurs in the obtained tire. It may occur. On the other hand, if the thickness of the first layer exceeds 0.6 mm, the tire weight increases and the fuel efficiency performance decreases. The thickness of the first layer is preferably 0.05 to 0.4 mm. The first layer can be obtained by forming SIBS into a film by an ordinary method of forming a thermoplastic resin or thermoplastic elastomer into a film such as extrusion molding or calendar molding.

<Second layer>
The second layer is composed of a SIS layer made of a styrene-isoprene-styrene triblock copolymer (hereinafter also referred to as “SIS”) and a styrene-isobutylene diblock copolymer (hereinafter also referred to as “SIB”). At least one of the SIB layers is included.

  Since the isoprene block of the styrene-isoprene-styrene triblock copolymer (SIS) is a soft segment, the thermoplastic elastomer film made of SIS is easily vulcanized and bonded to the rubber component. Therefore, when a thermoplastic elastomer film made of SIS is used for the inner liner, the inner liner is excellent in adhesion to the rubber layer of the carcass ply, for example, so that a pneumatic tire having excellent durability can be obtained. it can.

  The molecular weight of the SIS is not particularly limited, but from the viewpoint of rubber elasticity and moldability, the weight average molecular weight by GPC measurement is preferably 100,000 to 290,000. If the weight average molecular weight is less than 100,000, the tensile strength may be lowered, and if it exceeds 290,000, the extrusion processability is deteriorated. The content of the styrene component in the SIS is preferably 10 to 30% by mass in order to maintain tackiness, adhesiveness, and rubber elasticity.

  In the present invention, the polymerization degree of each block in SIS is preferably about 500 to 5,000 for isoprene and about 50 to 1,500 for styrene from the viewpoint of rubber elasticity and handling.

  The SIS can be obtained by a general vinyl compound polymerization method, for example, a living cationic polymerization method. The SIS layer can be obtained by forming the SIS into a film by a usual method of forming a thermoplastic resin or a thermoplastic elastomer into a film such as extrusion molding or calendar molding.

  Since the isobutylene block of the styrene-isobutylene diblock copolymer (SIB) is a soft segment, the thermoplastic elastomer film made of SIB is easily vulcanized and bonded to the rubber component. Therefore, when a thermoplastic elastomer film made of SIB is used for the inner liner, the inner liner is excellent in adhesion with, for example, a carcass or an adjacent rubber forming an insulation, so that the pneumatic tire has excellent durability. Can be obtained.

  It is preferable to use a linear SIB from the viewpoint of rubber elasticity and adhesiveness. The molecular weight of SIB is not particularly limited, but from the viewpoint of rubber elasticity and moldability, the weight average molecular weight by GPC measurement is preferably 40,000 to 120,000. If the weight average molecular weight is less than 40,000, the tensile strength may be lowered, and if it exceeds 120,000, the extrusion processability may be deteriorated.

  The content of the styrene component in the SIB is preferably 10 to 35% by mass in order to maintain tackiness, adhesiveness, and rubber elasticity. The degree of polymerization of each block in the SIB is preferably about 300 to 3,000 for isobutylene and about 10 to 1,500 for styrene from the viewpoint of rubber elasticity and handling.

  The SIB can be obtained by a general vinyl compound polymerization method, for example, a living cationic polymerization method. For example, in International Publication No. 2005/033035, methylcyclohexane, n-butyl chloride and cumyl chloride are added to a stirrer, cooled to −70 ° C., reacted for 2 hours, and then a large amount of methanol is added. A production method is disclosed in which the reaction is stopped and vacuum-dried at 60 ° C. to obtain SIB.

  The SIB layer can be obtained by forming SIB into a film by an ordinary method of forming a thermoplastic resin or thermoplastic elastomer into a film such as extrusion molding or calendering.

  The thickness of the second layer is 0.4 mm or less, preferably 0.01 mm to 0.3 mm. Here, the thickness of the second layer refers to the thickness of the SIS layer when the second layer is composed only of the SIS layer, and the thickness of the SIB layer when the second layer is composed of only the SIB layer. When a layer consists of two layers of an SIS layer and an SIB layer, it means the total thickness of the SIS layer and the SIB layer. When the thickness of the second layer is less than 0.01 mm, the second layer may be broken by the press pressure during vulcanization of the green tire in which the laminate is applied to the inner liner, and the vulcanization adhesive force may be reduced. On the other hand, when the thickness of the second layer exceeds 0.4 mm, the tire weight increases and the fuel efficiency performance decreases. The thickness of the second layer is preferably 0.01 to 0.3 mm.

<Strip manufacturing method>
A manufacturing method for manufacturing the strip 10 will be described with reference to FIG. The strip manufacturing apparatus 11 includes an extrusion apparatus 13 for extruding a sheet 12 of a thermoplastic elastomer having a horizontally long rectangular cross section, and a pair of mold rollers 14 disposed in the vicinity of the extrusion port 16.

  The extrusion device 13 includes an extruder main body 13A having a screw shaft 15 and an extrusion head 13B that forms a thermoplastic elastomer sheet discharged from the extruder main body 13A and extrudes it from an extrusion port 16. The extruder main body 13A kneads and melts the injected thermoplastic elastomer by the screw shaft 15 driven by an electric motor having a speed reducing function.

  The extrusion head 13B is provided with a die 17 for extrusion which is attached to the tip of the extruder body 13A and constitutes the extrusion port 16.

  Next, the pair of mold rollers 14 has a configuration having upper and lower rolls 14 </ b> A and 14 </ b> B, and is held in a lateral direction perpendicular to the direction of extrusion from the extrusion port 16. The upper and lower mold rolls 14A and 14B are driven and controlled to be rotatable at the same speed and in synchronization with each other.

  The shape of the gap between the upper and lower mold rolls 14A and 14B approximates the cross-sectional shape of the strip 10 as shown in FIG. Here, “approximate” is substantially similar to the cross-sectional shape of the strip 10, and considering the expansion, the similarity ratio is usually in the range of 0.50 to 0.90 and the gaps K 1 and K 2 Is smaller.

  That is, one or both of the upper and lower mold rolls 14A and 14B are provided with recessed portions 14a and 14b corresponding to the strip body 10A on the peripheral surface of the right cylindrical cylindrical roll body. Accordingly, the ear portion 10B is formed by the gap portion K1 between the mold rolls 14A and 14B, and the strip body 10A is formed by the gap portion K2 formed by the recessed portions 14a and 14b.

  As described above, in the manufacturing apparatus 11, first, the horizontally long rectangular sheet 12 is formed using the extrusion apparatus 13, and the shape of the mold roll is transferred to the sheet under the condition that no heat is generated in the mold roll molding. Then, the strip 12A on which the ear portion is formed is peeled from the mold roller 14B by the free roller 18 and processed into a final shape. Therefore, the accuracy and stability of the dimensions are improved, and the manufacturing efficiency can be improved, such as the need for a knife cutting operation for adjusting the width, which is usually required in calendar molding. In addition, the variation in the thickness T2 in the ear portion 10B can be reduced, and the high-quality strip 10 can be manufactured.

  For this purpose, the opening height HA1 of the extrusion port 16 in the extrusion head 13B is 2 to 7 times the thickness T1 of the strip, and the opening width WA1 of the extrusion port 16 is 0 of the width W0 of the strip. 0.7 to 1.0 times is preferable.

  When the opening height HA1 exceeds 7 times T1, and when the opening width WA1 is smaller than 0.7 times W0, the processing rate in the mold roll forming becomes excessive, and the quality and accuracy of the strip 10 are lowered. In particular, the width accuracy becomes unstable, and it is necessary to maintain the width accuracy by knife cutting. Further, when the opening height HA1 is smaller than twice T1, in order to obtain a strip 10 of 1.0 mm or less, the sheet thickness at the time of extrusion becomes thin, so that the extrusion pressure becomes high, and the dimensions are not good. It becomes stable. On the other hand, when the opening width WA1 exceeds 1 times W0, the processing rate is excessively reduced, and there is a problem that the strip 10 is cut, and the dimensional stability is also lowered.

  In addition, it is desirable that the mold roll and the free roll used in the molding process and the peeling process are subjected to a mold release process. The mold release treatment may be performed by, for example, nitriding the roll surface (radical nitridation, canak treatment) to form a Cr—N coating (hardness Hv: 200 to 800, film thickness: 25 to 500 μm), or hard chromium with Teflon ( Plating impregnated with (registered trademark) (hardness Hv: 800 to 1000, film thickness: 25 to 1000 μm), diamond-like carbon (DLC) coating (hardness Hv: 2000 to 7000, film thickness: 0.2 to 3. 0 μm) and Teflon (registered trademark) coating (hardness Hv: 100 to 500, film thickness: 0.1 to 0.5 μm) can be used.

<Method for producing thermoplastic elastomer composition>
The elastomer composition of the present invention can be produced by a conventionally known method. The above materials are weighed so as to have a predetermined blending ratio, and then kneaded at 100 to 250 ° C. for 5 to 60 minutes using a rubber kneading apparatus such as an open roll or a Banbury mixer.

  For example, SIBS, SMA, SMA base resin, SMA ester resin, SMA ammonium salt aqueous solution, and various additives as necessary are put into a twin screw extruder and kneaded under conditions of about 100 to 250 ° C. and 50 to 300 rpm. Thus, pellets of the thermoplastic elastomer composition in which each of these components is dynamically cross-linked are obtained.

  In the twin-screw extruder, SIBS, which is a thermoplastic elastomer composition, becomes a matrix phase and the rubber component becomes an island phase and is dispersed. Further, the rubber component and the additive component react in the twin-screw extruder, and the rubber component that is an island phase undergoes a crosslinking reaction. The rubber component is dynamically crosslinked (dynamic crosslinking) in a twin screw extruder. Even if the rubber component is cross-linked in the twin-screw extruder, the matrix phase of the system is composed of a thermoplastic elastomer component, so that the shear viscosity of the entire system is low and extrusion processing is possible.

  The pellets of the dynamically crosslinked thermoplastic elastomer composition obtained by the twin-screw extruder are crosslinked in the rubber component, but the thermoplastic elastomer component in the matrix phase retains the plasticity. Is maintained. For this reason, since plasticity is exhibited even in T-die extrusion, it can be formed into a sheet shape.

  Further, since the rubber component of the dynamically crosslinked thermoplastic elastomer composition pellets is crosslinked, a thermoplastic tire laminate produced using the pellets is applied to an inner liner to produce a pneumatic tire. Even if the pneumatic tire is heated at this time, it is possible to prevent the thermoplastic elastomer composition of the inner liner from entering the carcass layer.

<Molding of inner liner>
As shown in FIG. 5A, the strips 10 are sequentially wound spirally on the cylindrical drum D, and adjacent strips 10 form an inner liner while forming overlapping portions within a range of 3 mm to 38 mm. Here, when the strip 10 is wound, a step is formed between adjacent strips as shown in the enlarged view of FIG. 5B, but the uneven step d is relaxed by the ear. Become. On the other hand, as shown in FIG. 6 , the uneven step d0 in the case where a conventional strip having a rectangular cross section without an ear is used is about twice as large as the unevenness in the case of a strip having an ear. Yes.

  Thus, when the strip having the ear portion is used, it is easy to approximate the finished cross-sectional shape required for the inner liner. Moreover, a smooth contour shape can be obtained, and the occurrence of surface flaws after vulcanization can be prevented. On the other hand, the inner liner can be formed with the number of windings approximately the same as that of the conventional strip having the same thickness, and a reduction in production efficiency and generation of remaining air can be suppressed.

<Pneumatic tire manufacturing method>
A general manufacturing method can be used for the pneumatic tire of the present invention. A strip is produced using the laminate, and an inner liner is produced by the method described above. As described above, it can be produced by vulcanization molding of a green tire formed with an inner liner. When the laminated body is arranged on the raw tire, the SIS layer, which is the second layer of the laminated body, is arranged outward in the tire radial direction so as to be adjacent to the carcass ply. When arranged in this manner, the adhesive strength between the SIS layer and the carcass ply can be increased in the tire vulcanization step. The obtained pneumatic tire can have excellent air permeation resistance and durability since the inner liner and the rubber layer of the carcass ply are well bonded.

<Manufacture of inner liner>
According to the formulation shown in Table 1, various compounding agents were put into a twin-screw extruder (screw diameter: φ50 mm, L / D: 30, cylinder temperature: 220 ° C.) to be pelletized. Using this extruder (screw diameter: φ80 mm, L / D: 50, die gap width: 40 mm, cylinder temperature: 220 ° C.) shown in FIGS. 2 and 3, the screw rotation speed is 80 RPM, and the extrusion speed is about 9 m / In minutes, a ribbon-like sheet was extruded. And it passed through the mold rolls 14A and 14B, and manufactured the strip 12A which formed the ear | edge part of the predetermined shape at both ends.

  The ribbon-like sheet 12 is formed into a laminate by co-extruding the first layer and the second layer of thermoplastic elastomer using the extruder. Thereafter, the strip was peeled from the mold roller through a free roller 18 to obtain a strip 12A having a cross-sectional structure shown in FIG. Here, the width W0 and thickness T1 of the strip 10, the width W2 of the ear portion 10B, and the ear thickness T2 are as shown in Tables 1 to 4.

(Note 1) IIR: “Exon Chlorobutyl 1068” manufactured by ExxonMobil Corporation.
(Note 2) SIBS: “Sibstar SIBSTAR 102T” manufactured by Kaneka Corporation (Shore A hardness 25, styrene content 25% by mass).
(Note 3) SMA base resin: “SMA1000” manufactured by Sartomer (styrene component / maleic anhydride component: 50/50, weight average molecular weight: 5,500, acid value of maleic anhydride: 490).
(Note 4) SMA ester resin: “SMA1440” manufactured by Sartomer (styrene component / maleic anhydride component: 80/20, weight average molecular weight: 7,000, acid value of maleic anhydride: 200).
(Note 5) SMA ammonium salt aqueous solution: “SMA1000H” (pH 9.0) manufactured by Sartomer.
(Note 6) Carbon: “Seast V” (N660, N ₂ SA: 27 m ² / g) manufactured by Tokai Carbon Co., Ltd.
(Note 7) Stearic acid: “Lunac stearate S30” manufactured by Kao Corporation.
(Note 8) Zinc oxide: “Zinc Hana 1” manufactured by Mitsui Kinzoku Mining Co., Ltd.
(Note 9) Anti-aging agent: “NOCRACK 6C” (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
(Note 10) Vulcanization accelerator: “Noxeller DM” (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
(Note 11) Sulfur: “Powdered sulfur” manufactured by Tsurumi Chemical Co., Ltd.
(Note 12) SIS: D1161JP manufactured by Kraton Polymer Co., Ltd. (styrene component content 15 mass%, weight average molecular weight: 150,000).
(Note 13) SIB.

  To a 2 L reaction vessel equipped with a stirrer, 589 mL of methylcyclohexane (dried with molecular sieves), 613 ml of n-butyl chloride (dried with molecular sieves), and 0.550 g of cumyl chloride were added. After cooling the reaction vessel to −70 ° C., 0.35 mL of α-picoline (2-methylpyridine) and 179 mL of isobutylene were added. Further, 9.4 mL of titanium tetrachloride was added to initiate polymerization, and the reaction was allowed to proceed for 2.0 hours while stirring the solution at -70 ° C. Next, 59 mL of styrene was added to the reaction vessel, and the reaction was continued for another 60 minutes, and then a large amount of methanol was added to stop the reaction. After removing the solvent and the like from the reaction solution, the polymer was dissolved in toluene and washed twice with water. The toluene solution was added to a methanol mixture to precipitate a polymer, and the obtained polymer was dried at 60 ° C. for 24 hours to obtain a styrene-isobutylene diblock copolymer.

Styrene component content: 15% by mass
Weight average molecular weight: 70,000
<Manufacture of tires>
The above strip is wound on the drum shown in FIG. 5 and formed into a wide sheet by forming a joint portion between adjacent strips so that adjacent strips overlap each other by 5 mm. A sheet for an inner liner was manufactured.

  A pneumatic tire having a tire size of 195 / 65R15 was manufactured by using a strip based on the specifications shown in Tables 1 and 2 formed on an inner liner on a drum. The vulcanization was performed by pressing at 170 ° C. for 20 minutes, cooling at 100 ° C. for 3 minutes without removing from the vulcanization mold, and then removing from the vulcanization mold.

<Tire performance evaluation method>
The performance evaluation of the pneumatic tires of the examples and comparative examples in Table 1 was performed by the following method.

<Air-in performance>
The inside of the tire after vulcanization was inspected by appearance and the evaluation was as follows.

  A: When the number of air-ins with a diameter of 5 mm or less per tire is 0 and the number of air-ins with a diameter greater than 5 mm is 0 per appearance.

  B: When the number of air-ins with a diameter of 5 mm or less per tire is 1 to 3 and the number of air-ins with a diameter of more than 5 mm is zero per appearance.

  C: When the number of air-ins with a diameter of 5 mm or less per tire is 4 or more and the number of air-ins with a diameter of more than 5 mm is 1 or more.

<Bending crack growth test>
The flex crack growth test was evaluated based on whether the inner liner was cracked or peeled off. The prototype tire is assembled to a JIS standard rim 15 × 6 JJ, the tire internal pressure is set to 150 KPa, which is lower than usual, the load is 600 kg, the speed is 100 km / h, the traveling distance is 20,000 km, the inside of the tire is observed, cracks, The number of peels was measured. Based on Comparative Example 1, the crack growth property of each Example and Comparative Example was expressed as an index based on the following formula. The larger the number, the smaller the flex crack growth.

Bending crack growth index = (number of cracks in comparative example 1) / (number of cracks in each example and each reference example ) × 100
<Rolling resistance index>
Using a rolling resistance tester manufactured by Kobe Steel Co., Ltd., the prototype tire was assembled to a JIS standard rim 15 × 6JJ, and the temperature was set to room temperature (30 ° C.) under conditions of a load of 3.4 kN, an air pressure of 230 kPa, and a speed of 80 km / h. And rolling resistance was measured. And based on the following formula, the comparative example 1 was made into the reference | standard 100, and the rolling resistance change rate (%) of the Example was displayed by the index | exponent. It shows that rolling resistance is reduced, so that rolling resistance change rate is large.

Rolling resistance index = (Rolling resistance of comparative example 1 / rolling resistance of each example and each reference example ) × 100
<Static air pressure drop rate test>
The prototype tire was assembled into a JIS standard rim 15 × 6 JJ, filled with an initial air pressure of 300 kPa, and allowed to stand at room temperature for 90 days, and the rate of decrease in air pressure was calculated in one month. A smaller numerical value is preferable because the air pressure is less likely to decrease.

<Uniformity (RFV)>
Radial force variation (RFV) was measured in accordance with JASOC 607: 2000 uniformity test conditions. Relative values with Comparative Example 1 as 100 were displayed as an index. The larger the index, the better the uniformity. The measurement conditions were 8.0 × 17 for the rim, 60 rpm for the tire rotation speed, 200 kPa for the air pressure, and 4000 kN for the longitudinal load.

<Tire evaluation results>
In Examples 1 , 2, 4, 5, and Reference Example 7, the cross-sectional shape of the strip is as shown in FIG. 4A, and the mixing ratio of the styrene-isobutylene-styrene triblock copolymer and the SMA base resin in the first layer is This is a changed example. Example 4 is an example in which an SMA base resin and an SMA ester resin are mixed, and Example 5 is an example in which an SMA base resin and an aqueous SMA ammonium solution are mixed. In any of the examples, no air-in was observed, and an improvement in flex crack growth index, rolling resistance, static air reduction rate and uniformity was observed.

Reference Examples 1 to 3 are examples in which the cross-sectional shape of the strip is FIG. 4B and the mixing ratio of the styrene-isobutylene-styrene triblock copolymer and the SMA base resin in the first layer is changed. Reference Example 3 is an example in which an SMA base resin and an SMA ester resin are mixed. In any of the reference examples , no air-in was observed, and an improvement in flex crack growth index, rolling resistance, static air reduction rate and uniformity was observed.

Reference Examples 4 to 6 are examples in which the cross-sectional shape of the strip is FIG. 4C and the mixing ratio of the styrene-isobutylene-styrene triblock copolymer and the SMA base resin in the first layer is changed. Reference Example 6 is an example in which an SMA base resin and an SMA ester resin are mixed. In any of the reference examples , no air-in was observed, and an improvement in flex crack growth index, rolling resistance, and static air decrease rate was observed.

  Examples 12 to 14 are examples in which the cross-sectional shape of the strip is FIG. 4D and the mixing ratio of the styrene-isobutylene-styrene triblock copolymer and the SMA base resin in the first layer was changed. Example 14 is an example in which an SMA base resin and an SMA ester resin are mixed. In any of the examples, no air-in was observed, and an improvement in flex crack growth index, rolling resistance, static air reduction rate and uniformity was observed.

In Examples 15 and 16 and Reference Example 8 , the cross-sectional shape of the strip is as shown in FIG. 4A, and the mixing ratio of the styrene-isobutylene-styrene triblock copolymer and the SMA base resin in the first layer was changed. It is. Note that SIB is used for the second layer. Example 18 is an example in which an SMA base resin and an SMA ester resin were mixed. Example 19 is an example in which an SMA base resin and an aqueous SMA ammonium solution were mixed. In any of the examples, no air-in was observed, and an improvement in flex crack growth index, rolling resistance, static air reduction rate and uniformity was observed.

  Comparative Example 1 is an example in which the strip has a rectangular cross-sectional shape and IIR is used for the first layer. Comparative Example 2 is an example in which the strip has a rectangular cross-sectional shape and a mixture of styrene-isobutylene-styrene triblock copolymer and SMA base resin is used for the first layer. Comparative Example 3 is an example in which the strip cross-sectional shape is FIG. 4A and only the styrene-isobutylene-styrene triblock copolymer is used for the first layer. In Comparative Example 4, the cross-sectional shape of the strip is as shown in FIG. 4A, and 50% by mass of styrene-isobutylene-styrene triblock copolymer and 50% by mass of SMA base resin are mixed in the first layer. In Comparative Example 5, the cross-sectional shape of the strip is as shown in FIG. 4A, and 50% by mass of a styrene-isobutylene-styrene triblock copolymer and 50% by mass of an SMA ammonium aqueous solution are mixed in the first layer. In any of the comparative examples, air-in is observed, and it is recognized that the flex crack growth index, rolling resistance, and static air decrease rate are inferior.

  The pneumatic tire of the present invention can be used as a pneumatic tire for trucks and buses, heavy machinery, etc. in addition to a pneumatic tire for passenger cars.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 2 tread part, 3 side wall part, 4 bead part, 5 bead core, 6 carcass ply, 7 belt layer, 8 bead apex, 9 inner liner, 10 strip, 11 strip manufacturing apparatus, 12 sheets, 13 Extruder, 14A, 14B type roller, 15 screw shaft, 16 extrusion port, 17 base, 18
Free roller, PL laminate.

Claims (9)

The thermoplastic elastomer composition than Ri Na, causes wound spirally such that the strip body strip having ears disposed strip body and on both sides on the cylindrical drum to form a partially overlapping portion with each other An inner liner for a tire having a shape close to the finished cross-sectional shape formed by
The strip is a first layer comprising a thermoplastic elastomer composition containing 80 to 99.5% by mass of a styrene-isobutylene-styrene triblock copolymer and 0.5 to 20% by mass of a styrene-maleic anhydride copolymer. And a laminate of a second layer comprising a thermoplastic elastomer composition containing a styrene-isoprene-styrene triblock copolymer ,
Thickness before Symbol strip body (T1) is 0.1 mm to 0.6 mm, an average thickness in the width direction of the ear portion (T2) is thinner than the thickness (T1) of the strip body, the ears An inner liner having a width (W2) of 0.5 mm to 5.0 mm.   The inner liner according to claim 1, wherein the styrene-isobutylene-styrene triblock copolymer has a weight average molecular weight of 50,000 to 400,000 and a styrene component content of 10 to 30% by mass.   The styrene-maleic anhydride copolymer has a styrene component / maleic anhydride component molar ratio of 50/50 to 90/10, a weight average molecular weight of 4,000 to 20,000, and maleic anhydride. The inner liner of Claim 1 or 2 containing the styrene-maleic anhydride copolymer base resin whose acid value of a component is 50-600. The styrene - maleic anhydride copolymer, scan styrene - maleic anhydride copolymer base resin anhydride was obtained esterified styrene having a monoester group and a monocarboxylic acid - maleic anhydride copolymer The inner liner according to any one of claims 1 to 3, comprising an ester resin. The styrene - maleic anhydride copolymer, scan styrene - maleic anhydride copolymer base resin is dissolved in an ammonium salt, styrene - containing maleic anhydride copolymer ammonium salt solution, any of claims 1 to 4 The inner liner according to claim 1.   The inner liner according to any one of claims 1 to 4, wherein a width (W0) of the strip is 5 mm to 40 mm.   The inner liner according to any one of claims 1 to 5, wherein a thickness (T2) of an ear portion of the strip is 0.02 mm to 0.5 mm.   The inner liner according to claim 1, wherein the first layer has a thickness of 0.05 mm to 0.6 mm, and the second layer has a thickness of 0.01 mm to 0.3 mm. A method for producing a pneumatic tire using the inner liner according to claim 1,
(A) an extrusion step of extruding the thermoplastic elastomer composition to form a sheet having a horizontally long rectangular cross-sectional shape by an extrusion apparatus including an extruder body and an extrusion head;
(B) The sheet is passed through a pair of mold rollers, the shape of the mold roller is transferred to the sheet, and a strip forming step provided with an ear at the end of the strip;
(C) a peeling step of peeling the strip from the mold roller;
(D) a pneumatic tire including a step of spirally winding the strip on a cylindrical drum to form an inner liner, placing the inner liner on the inner surface of the green tire, and then pressing and vulcanizing. Manufacturing method.

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