JP6996902B2 - A method for producing a thermoplastic elastomer composition, a method for producing an air-permeable film for a tire, and a method for producing a pneumatic tire. - Google Patents

Description

The present invention relates to a method for producing a thermoplastic elastomer composition, a method for producing an air-permeable film for a tire, and a method for producing a pneumatic tire.

An inner liner is provided on the inner surface of the pneumatic tire as an air permeation suppressing layer in order to keep the air pressure of the tire constant. The inner liner is generally composed of a rubber layer such as butyl rubber or halogenated butyl rubber, which is difficult for gas to permeate. However, in order to reduce the weight of the tire, the use of a thin resin film is being considered.

As a resin film used for tires for cold regions, it is required to improve low temperature durability while maintaining air permeability resistance.

Such an air-permeable resin film is obtained by melt-kneading a rubber component and a thermoplastic resin and dynamically cross-linking the resin. The thermoplastic resin is a continuous phase (matrix phase) and the rubber component is a dispersed phase. A thermoplastic elastomer composition (Thermoplastic Vulcanizates; TPV) having a sea-island structure (domain phase) is used.

For example, in Patent Document 1, at least 5% of the halogen portion of the halogenated rubber is (i) a chain polymer having a carboxyl group or an amino group at the terminal and having a weight average molecular weight of 1000 or more, or (ii) a carboxyl group or an amino. Thermoplastic, which is a dynamically crosslinked product in which the modified halogenated rubber (A) substituted with a non-polymer compound having a group and having an intermolecular interaction is used as a dispersed phase and the thermoplastic resin (B) is used as a continuous phase. Polymer compositions are disclosed (claims 1, 4, paragraph 0020, etc.). However, there was room for further improvement in low temperature durability of this resin film.

Further, in Patent Document 2, the rubber composition (B) is kneaded at a temperature of 120 ° C. or lower in the presence of a cross-linking agent, and then the component (A) polyamide resin and (C) processing aid are melt-kneaded and kneaded to rubber. It is possible to use a thermoplastic elastomer composition having a structure in which the rubber composition (B) is dispersed in the polyamide resin (A), which is obtained by dynamically cross-linking the components and whose stress satisfies a predetermined requirement. It has been proposed (claim 1). However, this is because the stress at 2.5% elongation of the stress-strain curve is 0.1-50 MPa, the stress at -20 ° C and 200% elongation (M200) and the stress at -20 ° C and 100% elongation. Since it is necessary to adjust the ratio to (M100) within the specified range of 1.0 <M200 / M100 <2.0, the manufacturing work is complicated and a processing aid is added. Since the adhesiveness between the inner liner and the rubber layer such as carcass is lowered, the air permeability may be deteriorated.

Japanese Patent Application Laid-Open No. 2003-89702 Japanese Patent No. 4942253

As a result of diligent studies, the present inventor unexpectedly maintains air permeability by using butadiene rubber, which was conventionally considered to have poor air permeability, as the dispersed phase of the thermoplastic elastomer composition. It has been found that the low temperature durability can be improved, and in particular, the effect becomes remarkable when butadiene rubber and butyl rubber are used in combination as a dispersed phase.

However, since butadiene rubber and butyl rubber have different cross-linking rates, the dispersed phase of the thermoplastic elastomer composition obtained by dynamically cross-linking them may be partially cross-linked or partially cross-linked insufficiently. There were variations in the state of cross-linking. There was room for further improvement in low temperature durability by suppressing this variation in the crosslinked state.

In view of the above points, the present invention relates to a method for producing a thermoplastic elastomer composition and a method for producing an air-permeable film for a tire, which can obtain a resin film having improved low-temperature durability while maintaining at least air permeability resistance. , And a method of manufacturing a pneumatic tire.

The method for producing a thermoplastic elastomer composition of the present invention is a method for producing a thermoplastic elastomer composition that dynamically crosslinks a rubber component and a thermoplastic resin, and contains a butadiene rubber and a crosslinking agent, and substantially comprises butyl rubber. A step of producing a rubber pellet (A) not contained, a step of producing a rubber pellet (B) containing butyl rubber and a cross-linking agent and substantially free of butadiene rubber, and the rubber pellet (A) and the rubber pellet (the rubber pellet (A)). The step of melt-kneading the B) and the thermoplastic resin is included, and the cross-linking agent contained in the rubber pellet (A) and the rubber pellet (B) is an alkylphenol-formaldehyde condensate or a brominated alkylphenol-formaldehyde condensate. Suppose there is.

The rubber pellet (B) may further contain zinc oxide.

The rubber pellet (B) can further contain stearic acid.

In the method for producing an air-permeable film for tires of the present invention, the air-permeable film for tires is produced using the thermoplastic elastomer composition obtained by the above-mentioned production method.

In the method for manufacturing a pneumatic tire of the present invention, the pneumatic tire is manufactured by using the air-permeable film for tires obtained by the above manufacturing method.

According to the production method of the present invention, a thermoplastic elastomer composition that can obtain a resin film having improved low temperature durability while maintaining air permeability resistance, an air permeability resistant film for tires using the same, and the same. A tire using the above can be obtained.

It is sectional drawing of the pneumatic tire obtained by the manufacturing method which concerns on one Embodiment of this invention.

Hereinafter, matters related to the practice of the present invention will be described in detail.

The method for producing a thermoplastic elastomer composition according to the present embodiment is a method for producing a thermoplastic elastomer composition in which a rubber component and a thermoplastic resin are dynamically cross-linked, and comprises a butadiene rubber (BR) and a cross-linking agent. A step of producing a rubber pellet (A) substantially free of butyl rubber (IIR) and a rubber pellet (B) containing butyl rubber (IIR) and a cross-linking agent and substantially free of butadiene rubber (BR). It includes a step and a step of melt-kneading the rubber pellet (A), the rubber pellet (B), and the thermoplastic resin. Here, "substantially free" means a content in a range in which no significant action or effect is observed depending on the content thereof, and is usually butyl rubber in the rubber component contained in the rubber pellet (A). The content of butadiene rubber is less than 1% by mass, preferably less than 0.1% by mass, and the content of butadiene rubber in the rubber component contained in the rubber pellet (B) is less than 1% by mass. It is preferably less than 1% by mass.

By the production method of this embodiment, a thermoplastic elastomer composition having a sea-island structure having a thermoplastic resin as a continuous phase (matrix phase) and a rubber component as a dispersed phase (domain phase) can be obtained.

In this way, butadiene rubber and butyl rubber are mixed in different mixing systems to form a master batch, and using rubber pellets with cross-linking conditions suitable for each, they are melt-kneaded together with a thermoplastic resin and dynamically cross-linked. Therefore, the crosslinked state in the dispersed phase can be homogenized. The kneading machine used for kneading is not particularly limited, and examples thereof include a twin-screw extruder, a screw extruder, a kneader, and a Banbury mixer. The melt-kneading conditions are not particularly limited, but for example, kneading can be performed at a rotation speed of 100 to 300 rpm for 1 to 3 minutes at 200 to 250 ° C. The particle size of the dispersed phase of the thermoplastic elastomer composition is not particularly limited, but the average particle size is preferably 0.1 to 2 μm, more preferably 0.1 to 1 μm.

Examples of the thermoplastic resin include nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymer, nylon 6/66/610 copolymer, nylon MXD6, and the like. Polypolymeric resins such as nylon 6T and nylon 6 / 6T copolymers; polybutylene terephthalate (PBT), potiethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), Polyester resins such as polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimide acid / polybutyrate terephthalate copolymer; polyacrylonitrile (PAN), polymethacrylic nitrile, acrylonitrile / styrene copolymer (AS) , Polynitrile-based resins such as methacrylonitrile / styrene copolymers, methacrylate-based resins such as methacrylonitrile / styrene / butadiene copolymers; cellulose-based resins such as cellulose acetate and butyrate butyrate acetate; polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF). ), Polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE) and other fluororesins; imide-based resins such as aromatic polyimide (PI), each of which may be used alone or in combination of two or more. Can be used in combination.

As the rubber component, butadiene rubber (BR) and butyl rubber (IIR) are used, but other rubber components may be contained as long as the effects of the present invention are not impaired. Examples of such rubber components include natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene butadiene rubber (SBR), nitrile rubber (NBR), and hydride nitrile rubber (H-). Diene rubbers such as NBR) and hydride styrene butadiene rubbers and their hydrogenated rubbers; olefin rubbers such as ethylene propylene rubber (EPDM), maleic acid modified ethylene propylene rubber, maleic acid modified ethylene butylene rubber, acrylic rubber (ACM). Halogen-containing butyl rubber (eg, brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR)), chloroprene rubber (CR), chlorosulfonated polyethylene and other halogen-containing rubbers; Examples include polysulfide rubber.

The ratio of the butadiene rubber (BR) and the butyl rubber (IIR) in the rubber component is preferably 80 to 100% by mass, more preferably 90 to 100% by mass in the total amount.

The proportion of butadiene rubber in the rubber component in the rubber pellet (A) is preferably 80 to 100% by mass, more preferably 90 to 100% by mass.

The proportion of butyl rubber in the rubber component in the rubber pellet (B) is preferably 80 to 100% by mass, more preferably 90 to 100% by mass.

Various compounding agents generally blended in the rubber composition, such as a cross-linking agent, zinc oxide, stearic acid, a filler, a softening agent, and an antiaging agent, can be appropriately added to the rubber component of the present embodiment. That is, the rubber component may consist of a rubber composition obtained by adding various compounding agents to a rubber polymer.

Examples of the cross-linking agent for dynamically cross-linking the rubber component include vulcanizing agents such as sulfur and sulfur-containing compounds, vulcanization accelerators, and phenolic resins. From the viewpoint of heat resistance, it is preferable to use a phenol-based resin. Examples of the phenol-based resin include a resin obtained by a condensation reaction between phenols and formaldehyde, and an alkylphenol-formaldehyde condensate or a brominated alkylphenol-formaldehyde condensate is more preferable, and an alkylphenol-formaldehyde condensate is used. Is particularly preferable.

The cross-linking agent to be blended in the rubber pellet (A) is not particularly limited, and a cross-linking agent suitable for butadiene rubber can be selected and used from the above-mentioned cross-linking agents, but it may be an alkylphenol-formaldehyde condensate. preferable.

The cross-linking agent to be blended in the rubber pellet (B) is not particularly limited, and a cross-linking agent suitable for butyl rubber can be selected and used from the above-mentioned cross-linking agents, but an alkylphenol-formaldehyde condensate is preferable. .. Further, since butyl rubber has a slow cross-linking rate, it is preferable that the rubber pellet (B) contains zinc oxide in addition to the above-mentioned cross-linking agent, and more preferably, the alkylphenol-formaldehyde condensate is used in combination with zinc oxide. be. If the cross-linking rate becomes too high due to the combined use of the cross-linking agent and zinc oxide, it is particularly preferable to further contain stearic acid.

The compounding ratio of the butadiene rubber contained in the rubber pellet (A) and the butyl rubber contained in the rubber pellet (B) (the ratio as a polymer component excluding the compounding agent such as a filler) is not particularly limited, but is a mass ratio. (Butadiene rubber / butyl rubber) is preferably about 10/90 to 90/10, more preferably 20/80 to 85/15.

The amount of the cross-linking agent to be blended in the rubber pellet (A) is not particularly limited as long as the butadiene rubber can be cross-linked appropriately, and varies depending on the type, but as a guide, it is 0.1 with respect to 100 parts by mass of the butadiene rubber. It is preferably up to 10 parts by mass, more preferably 1 to 5 parts by mass.

The amount of the cross-linking agent to be blended in the rubber pellet (B) is not particularly limited as long as the butyl rubber can be cross-linked appropriately, and varies depending on the type, but as a guide, 0.1 to 10 to 100 parts by mass of the butyl rubber. It is preferably parts by mass, more preferably 1 to 5 parts by mass.

When zinc oxide is blended in the rubber pellet (B), the blending amount is not particularly limited as long as the butyl rubber can be appropriately crosslinked, and varies depending on the type of the cross-linking agent. It is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass.

When stearic acid is blended in the rubber pellets (B), the blending amount is not particularly limited as long as the butyl rubber can be appropriately crosslinked, and varies depending on the type of the cross-linking agent. It is preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass.

Sulfur as a cross-linking agent is not essential, and as the cross-linking system, only a vulcanization accelerator or a phenol-based resin may be blended. When the thermoplastic elastomer composition obtained by the production method according to the present embodiment is used as an air-permeable film for tires, it is preferable to co-crosslink the rubber member to be bonded or the rubber layer during vulcanization molding. However, when sulfur is blended, the cross-linking of the rubber component proceeds too much depending on the temperature at which the air-permeable film is produced, and the above-mentioned co-crosslinking becomes difficult.

The various compounding agents arbitrarily added to the rubber component may be added to the rubber component in advance, or may be added during the melt-kneading of the thermoplastic resin and the rubber component.

The kneading conditions for producing the rubber pellets (A) and the rubber pellets (B) are, for example, dry mixing at a temperature of 60 to 80 ° C. at a rotation speed of 50 to 100 for 1 to 5 minutes. can. The kneader used for this kneading is not particularly limited, and examples thereof include a twin-screw extruder, a screw extruder, a kneader, and a Banbury mixer.

The compounding ratio of the thermoplastic resin and the rubber component (ratio as a polymer component excluding the compounding agent such as a filler) varies depending on the type of the thermoplastic resin and is not particularly limited, but is a mass ratio (thermoplastic resin /). The rubber component) is usually preferably about 60/40 to 25/75, and more preferably 50/50 to 30/70.

The method for producing a thermoplastic elastomer composition according to the present embodiment may be a mixture of a thermoplastic resin and a rubber component together with a compatibilizer. By blending the compatibilizer, the interfacial tension between the thermoplastic resin and the rubber component can be reduced, and the dispersed phase of the sea-island structure can be made finer. As the compatibilizer, as one embodiment, an ethylene-glycidyl (meth) acrylate copolymer (that is, an ethylene-glycidyl methacrylate copolymer and / or an ethylene-glycidyl acrylate copolymer) may be used. The blending amount of the compatibilizer is not particularly limited, but may be 0.5 to 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

When the thermoplastic elastomer composition obtained by the production method according to the present embodiment is applied to an air-permeable film for tires, a resorcin-based formaldehyde condensate may be blended as an adhesiveness improver. The adhesiveness improver is added to improve the adhesiveness between the air-permeable film and the adjacent rubber member in the tire. As the resorcin-based formaldehyde condensate, a phenol compound containing at least a part of resorcin and a compound obtained by condensing formaldehyde are used. Preferably, a resorcin-alkylphenol-formaldehyde copolymer or a modified resorcin-formaldehyde resin is used. The modified resorcin-formaldehyde resin is one in which an unsaturated group-containing monomer is bonded to at least a part of a phenol compound forming a skeleton to form a side chain of an arylalkyl group (aralkyl group) or a grafted polymer chain. , Or a polymer of an unsaturated group-containing monomer or a mixture of a polymer thereof and resorcin, or the like. Further, it may partially contain an aldehyde compound other than formaldehyde. For example, at least one selected from styrene, α-methylstyrene, p-methylstyrene, α-chlorostyrene, divinylbenzene, vinylnaphthalene, inden, and vinyltoluene (particularly preferably styrene) coexists with resorcin and formaldehyde. It may be a reaction product obtained by mixing a small amount of butyl aldehyde or other aldehyde. The blending amount of the resorcin-based formaldehyde condensate is not particularly limited, but is 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the thermoplastic resin and the rubber component (amount as a polymer excluding the blending agent such as a filler). can do.

As a method for producing a thermoplastic elastomer composition of one embodiment, first, a butadiene rubber and a cross-linking agent are put into a kneader and kneaded to prepare a rubber pellet (A) of a rubber masterbatch. Further, the butyl rubber and the cross-linking agent are put into another kneader and kneaded to prepare rubber pellets (B) of a rubber masterbatch. The obtained rubber pellets (A) and rubber pellets (B) and the thermoplastic resin are put into a kneader together with a compatibilizer, melt-kneaded and dynamically crosslinked to obtain pellets of the thermoplastic elastomer composition. Obtainable. The compatibilizer may be added when the rubber component and the thermoplastic resin are melt-kneaded as described above, or may be kneaded with the thermoplastic resin in advance.

The adhesiveness improver may be added at the same time as the rubber component, and may be before or after the dynamic cross-linking. However, when the phenolic resin is added as the cross-linking agent, the adhesiveness improver should be added after the dynamic cross-linking. Is preferable. The melt-kneading conditions in this case are not particularly limited, but it is preferable to knead at 200 to 250 ° C. at a rotation speed of 100 to 300 rpm for 1 to 3 minutes.

By filming the pellets of the thermoplastic elastomer composition thus obtained, the air-permeable film according to the embodiment of the present invention can be obtained. The method for forming a film is not particularly limited, and a method for forming a normal thermoplastic resin into a film, such as extrusion molding or calender molding, can be used.

The thickness of the air-permeable film is not particularly limited because it depends on the application, but for example, in the case of a tire application, it can be 0.02 to 1.0 mm, preferably 0.05 to 0.5 mm, and more. It is preferably 0.05 to 0.3 mm.

The air permeability of the air-permeable film is also not particularly limited because it depends on the application, but for tire applications, it conforms to JIS K7126-1 "Plastic-Film and Sheet-Gas Permeability Test Method-Part 1: Differential Pressure Method". It is preferable that the value measured at the test gas: air and the test temperature: 80 ° C. has at least the same level of air permeability resistance as the inner liner composed of a rubber layer such as butyl rubber or butyl halide rubber. It is preferably 0 × 10 ¹³ fm ² / Pa · s or less.

The air-permeable film obtained by the manufacturing method according to the present embodiment includes, for example, various automobile tires including passenger car tires, heavy-duty tires such as trucks and buses, and motorcycle tires including bicycles. Can be applied to pneumatic tires.

FIG. 1 is a cross-sectional view of a pneumatic tire 1 obtained by the manufacturing method according to the embodiment. As shown in the figure, the pneumatic tire 1 is provided between a pair of bead portions 2 assembled on a rim, a pair of sidewall portions 3 extending outward in the radial direction of the tire from the bead portions 2, and the pair of sidewall portions 3. It is composed of a tread portion 4 that is in contact with the provided road surface. A ring-shaped bead core 5 is embedded in each of the pair of bead portions 2. The carcass ply 6 using the organic fiber cord is folded around the bead core 5 and locked, and is provided so as to be bridged between the left and right bead portions 2. Further, on the outer peripheral side of the tread portion 4 of the carcass ply 6, a belt 7 composed of two belt plies using a rigid tire cord such as a steel cord or an aramid fiber is provided.

An inner liner 8 is provided inside the carcass ply 6 over the entire inner surface of the tire. In the present embodiment, the air-resistant film is used as the inner liner 8. As shown in the enlarged view in FIG. 1, the inner liner 8 is attached to the inner surface of the carcass ply 6, which is a rubber layer on the inner surface side of the tire, and more specifically, the topping rubber covering the cord of the carcass ply 6. It is attached to the inner surface of the layer.

As a method for manufacturing a pneumatic tire using the air-permeable film according to the present embodiment, for example, the air-permeable film is used as an inner liner, and the inner liner is attached to the outer periphery of the molded drum in a tubular shape. A green tire (unvulcanized tire) is manufactured by pasting a carcass ply on it, further laminating each tire member such as a belt, tread rubber and sidewall rubber, and inflating it, and the green tire is placed in a mold. By vulcanizing and molding with, a pneumatic tire can be obtained.

In the example shown in FIG. 1, the air-permeable film is provided on the inner surface side of the carcass ply, but it is possible to prevent the permeation of air from the inside of the tire and maintain the air pressure of the tire, that is, the internal pressure. As long as it is provided as an air permeation suppressing layer for holding, it can be provided at various positions such as, for example, on the outer surface side of the carcass ply, and is not particularly limited.

Hereinafter, examples of the present invention will be shown, but the present invention is not limited to these examples.

According to the formulation (parts by mass) shown in Table 1, a cross-linking agent, zinc oxide, and stearic acid were dry-mixed with the rubber component at a temperature of 70 ° C. or lower using a kneader to obtain rubber pellets 1 to 10.

According to the formulations (parts by mass) shown in Tables 2 to 5, the obtained rubber pellets 1 to 10 and the thermoplastic resin were mixed with a compatibilizer and a twin-screw extruder (Plastic Industry Research Institute) at a temperature of 220 ° C. It was melt-kneaded using and dynamically cross-linked to obtain pellets of a thermoplastic elastomer composition. The obtained pellets were molded into a width of 14 cm and a thickness of 0.2 mm using a single-screw extruder to obtain a film sample.

The details of each component in Tables 1 to 5 are as follows.
・ BR: "UBEPOL BR150L" manufactured by Ube Industries, Ltd.
-IIR: "IIR268" manufactured by ExxonMobil Chemical Co., Ltd.
-Crosslinking agent: "Tackiroll 250-III" manufactured by Taoka Chemical Industry Co., Ltd.
・ Zinc Oxide: "Zinc Oxide No. 1" manufactured by Mitsui Mining & Smelting Co., Ltd.
-Stearic acid: "Lunac S-20" manufactured by Kao Corporation
-Nylon 6/66: DSM "Novamid 2020J"
・ Compatibility agent: "Bond First E" manufactured by Sumitomo Chemical Co., Ltd.

The low temperature durability and air permeability were evaluated for each sample consisting of the obtained thermoplastic elastomer composition. Each evaluation method is as follows.

-Low temperature durability: Using each sample, a JIS K6270 dumbbell No. 3 test piece was prepared, and the dumbbell-shaped test piece was sandwiched between chucks in an atmosphere of -20 ° C and vibrated at 5 Hz. The number was repeatedly stretched by 50%. The number of test pieces was 10, and after stretching 100,000 times, the number of films with breakage was examined. The smaller the number of breaks, the better the low temperature durability.

-Air permeability: According to JIS K7126-1 "Plastic-Film and Sheet-Gas Permeability Test Method-Part 1: Differential Pressure Method", test gas: air, test temperature: 80 ° C. be. The smaller this value, the better the air permeability resistance.

The results are as shown in Tables 1 to 5, and the air permeability values of each Example and Comparative Example are 5.0 × 10 ¹³ fm ² / Pa · s or less, and excellent air permeability resistance is obtained. It was confirmed to have.

Regarding the low temperature durability, in Example 1, Comparative Example 1 in which the rubber pellet 2 containing butyl rubber and a cross-linking agent as a rubber component was used alone, and the rubber pellet 5 containing butadiene rubber and butyl rubber and a cross-linking agent were used. Compared with Comparative Example 2 used, the low temperature durability was excellent.

Example 2 was superior in low temperature durability as compared with Comparative Example 3 using butadiene rubber and rubber pellets 6 containing butyl rubber and a cross-linking agent.

Examples 3 and 4 are Comparative Example 4 using butadiene rubber and rubber pellets 7 containing butyl rubber and a cross-linking agent, and Comparative Example 5 using butadiene rubber and butyl rubber and rubber pellets 9 containing a cross-linking agent and zinc flower. , Butyl rubber, and rubber pellets 10 containing a cross-linking agent, zinc flower, and stearic acid were used, and the low temperature durability was excellent as compared with Comparative Example 6.

Example 5 was superior in low temperature durability as compared with Comparative Example 7 using butadiene rubber and rubber pellets 8 containing butyl rubber and a cross-linking agent.

The thermoplastic elastomer composition obtained by the production method of the present invention can be used as an inner liner for various tires of passenger cars, light trucks, buses and the like.

1 ... Pneumatic tire 2 ... Bead 3 ... Sidewall 4 ... Tread 5 ... Bead core 6 ... Carcass ply 7 ... Belt 8 ... Inner liner

Claims (5)

A method for producing a thermoplastic elastomer composition that dynamically crosslinks a rubber component and a thermoplastic resin.
A step of producing a rubber pellet (A) containing butadiene rubber and a cross-linking agent and substantially free of butyl rubber, and
A step of producing a rubber pellet (B) containing butyl rubber and a cross-linking agent and substantially free of butadiene rubber.
A step of melt-kneading the rubber pellet (A), the rubber pellet (B), and the thermoplastic resin is included.
A method for producing a thermoplastic elastomer composition, wherein the cross-linking agent contained in the rubber pellet (A) and the rubber pellet (B) is an alkylphenol-formaldehyde condensate or a brominated alkylphenol-formaldehyde condensate . The method for producing a thermoplastic elastomer composition according to claim 1, wherein the rubber pellet (B) further contains zinc oxide. The method for producing a thermoplastic elastomer composition according to claim 2 , wherein the rubber pellet (B) further contains stearic acid. A method for producing an air-permeable film for a tire, which comprises producing an air-permeable film for a tire by using the thermoplastic elastomer composition obtained by the production method according to any one of claims 1 to 3 . A method for manufacturing a pneumatic tire, wherein the pneumatic tire is manufactured by using the air-resistant film for a tire obtained by the manufacturing method according to claim 4 .

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