JPWO2018123192A1 - Thermoplastic resin composition, inner liner and pneumatic tire - Google Patents

Abstract

Disclosed is a thermoplastic resin composition capable of producing an inner liner for a pneumatic tire that is excellent in low-temperature durability and has little deterioration in gas barrier properties due to fatigue. A thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and a polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, wherein the composition is ethylene-vinyl alcohol. A phthalic acid ester having a molecular weight of 270 or less is contained in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the copolymer.

Description

  The present invention relates to a thermoplastic resin composition, an inner liner for a pneumatic tire made of the thermoplastic resin composition, and a pneumatic tire including the inner liner. More specifically, the present invention relates to a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, and its thermoplasticity. The present invention relates to an inner liner for a pneumatic tire made of a resin composition and a pneumatic tire including the inner liner.

  Thermoplastic in which a rubber composition containing a halogenated isoolefin paraalkylstyrene copolymer is dispersed in a thermoplastic resin composition containing polyamide and ethylene vinyl alcohol copolymer or polyvinyl alcohol, and the rubber composition is crosslinked. An elastomer composition is known (Japanese Patent Laid-Open No. 2012-46614).

JP 2012-46614 A

However, a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer is used as an inner liner of a pneumatic tire. Gas barrier properties slightly decrease due to fatigue.
The present invention relates to a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and a polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer as a material for a tire inner liner. It is an object of the present invention to provide a thermoplastic resin composition that is capable of producing an inner liner that is excellent in durability and less deteriorated in gas barrier properties due to fatigue when used as an adhesive.

  The inventor of the present invention provides a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer having a molecular weight of 270 or less. It has been found that by blending a certain phthalate ester, the deterioration of the gas barrier property due to fatigue can be effectively suppressed, and both durability and gas barrier property can be achieved, and the present invention has been completed.

  The present invention is a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and a polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, wherein the composition is A phthalic acid ester having a molecular weight of 270 or less is contained in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of an ethylene-vinyl alcohol copolymer.

The present invention includes the following aspects.
[1] A thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, wherein the composition is ethylene -A thermoplastic resin composition comprising 0.5 to 20 parts by weight of a phthalic acid ester having a molecular weight of 270 or less based on 100 parts by weight of a vinyl alcohol copolymer.
[2] The thermoplastic resin composition according to [1], wherein the phthalate ester is dimethyl phthalate or diethyl phthalate.
[3] The weight ratio of the ethylene-vinyl alcohol copolymer and the polyamide contained in the matrix phase (ethylene-vinyl alcohol copolymer / polyamide) is 95/5 to 40/60, in [1] or [2] The thermoplastic resin composition as described.
[4] The halogenated isomonoolefin-paraalkylstyrene copolymer is 10 to 150 parts by weight based on 100 parts by weight of the total amount of the ethylene-vinyl alcohol copolymer and the polyamide, according to [1] to [3] The thermoplastic resin composition according to any one of the above.
[5] The thermoplastic resin composition according to any one of [1] to [4], wherein the dispersed phase further contains an elastomer having an acid anhydride group.
[6] The thermoplastic resin composition according to any one of [1] to [5], wherein the halogenated isomonoolefin-paraalkylstyrene copolymer is dynamically crosslinked with a crosslinking agent.
[7] An inner liner for a pneumatic tire comprising the thermoplastic resin composition according to any one of [1] to [6].
[8] A pneumatic tire including the inner liner according to [7].

  The thermoplastic resin composition of the present invention can produce an inner liner that is excellent in low-temperature durability and has little deterioration in gas barrier properties due to fatigue.

  The present invention is a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and a polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, wherein the composition is A phthalic acid ester having a molecular weight of 270 or less is contained in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of an ethylene-vinyl alcohol copolymer.

  By blending a phthalate with a thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and a polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, A decrease in gas barrier properties due to fatigue of the plastic resin composition can be efficiently suppressed, and both durability and gas barrier properties can be achieved.

The phthalate used in the present invention has a molecular weight of 270 or less, preferably 100 to 260, and more preferably 130 to 250. If the molecular weight is too high, there is a possibility that deterioration of gas barrier properties due to fatigue cannot be suppressed.
Specific examples of the phthalate ester plasticizer having a molecular weight of 270 or less include dimethyl phthalate (molecular weight: 194.2), ethyl methyl phthalate (molecular weight: 208.2), diethyl phthalate (molecular weight: 222.2). ), Dipropyl phthalate (molecular weight: 250.3). Of these, dimethyl phthalate and diethyl phthalate are preferable from the viewpoint of suppressing a decrease in gas barrier properties due to fatigue.
The phthalic acid ester to be used may be one kind or a mixture of two or more kinds.
Moreover, the phthalic acid ester whose molecular weight exceeds 270 may be contained in the range which does not inhibit the effect of this invention.

  The blending amount of the phthalic acid ester having a molecular weight of 270 or less is 0.5 to 20 parts by weight, preferably 0.8 to 15 parts by weight, based on 100 parts by weight of the ethylene-vinyl alcohol copolymer. Preferably it is 1-10 weight part. If the blending amount of the phthalic acid ester having a molecular weight of 270 or less is too small, the effect of suppressing the deterioration of gas barrier properties due to fatigue may not be sufficient, and conversely if too large, the gas barrier properties before fatigue may be deteriorated. .

  The thermoplastic resin composition of the present invention comprises a matrix phase and a dispersed phase. In other words, the thermoplastic resin composition of the present invention has a so-called sea-island structure. The matrix phase includes an ethylene-vinyl alcohol copolymer and a polyamide. The dispersed phase contains a halogenated isomonoolefin-paraalkylstyrene copolymer. The dispersed phase preferably further comprises an elastomer having acid anhydride groups. Phthalates are mainly contained in the matrix phase.

The ethylene-vinyl alcohol copolymer (hereinafter also referred to as “EVOH”) used in the present invention is composed of an ethylene unit (—CH ₂ CH ₂ —) and a vinyl alcohol unit (—CH ₂ —CH (OH) —). However, in addition to the ethylene unit and the vinyl alcohol unit, the copolymer may contain other structural units as long as the effects of the present invention are not impaired. The ethylene-vinyl alcohol copolymer used in the present invention has an ethylene unit content, that is, an ethylene composition ratio of preferably 32 to 48 mol%, more preferably 38 to 48 mol%. If the ethylene composition ratio of the ethylene-vinyl alcohol copolymer is too small, the flexibility of the ethylene-vinyl alcohol copolymer is reduced and the durability is lowered. On the other hand, if the ethylene composition ratio is too high, the gas barrier property is lowered. The ethylene-vinyl alcohol copolymer is a saponified product of an ethylene-vinyl acetate copolymer, and the saponification degree is preferably 90% or more, more preferably 98% or more. If the saponification degree of the ethylene-vinyl alcohol copolymer is too small, the gas barrier property is lowered and the thermal stability is also lowered. The ethylene-vinyl alcohol copolymer is commercially available, for example, from Kuraray Co., Ltd. under the trade name “EVAL” (registered trademark), and from Nippon Synthetic Chemical Industry Co., Ltd. under the product name “Soarnol” (registered trademark). It can be obtained. As an ethylene-vinyl alcohol copolymer having an ethylene composition ratio of 32 to 48 mol% and a saponification degree of 90% or more, “EVAL” (registered trademark) H171B manufactured by Kuraray Co., Ltd. (ethylene composition ratio 38 mol%, saponification degree) 99% or more), E171B (ethylene composition ratio 44 mol%, saponification degree 99% or more), “Soarnol” (registered trademark) H4815B (ethylene composition ratio 48 mol%, saponification degree 99%) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. A4412B (ethylene composition ratio 42 mol%, saponification degree 99% or more), DC3212B (ethylene composition ratio 32 mol%, saponification degree 99% or more), and the like.

  The polyamide used in the present invention is not limited, but nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, nylon 610, nylon 612, nylon 6/66, nylon 6/66/12, nylon MXD6, nylon 6T, nylon 9T, etc. are mentioned. Among these, nylon 6, nylon 6/66, and nylon 612 are preferable in terms of both durability and gas barrier properties.

  The weight ratio of ethylene-vinyl alcohol copolymer and polyamide (ethylene-vinyl alcohol copolymer / polyamide) is preferably 95/5 to 40/60, more preferably 90/10 to 45/55, More preferably, it is 85 / 15-50 / 50. When the proportion of the ethylene-vinyl alcohol copolymer is too low, the gas barrier property before fatigue is not sufficient, and when the proportion of the ethylene-vinyl alcohol copolymer is too high, the low-temperature durability is deteriorated.

The halogenated isomonoolefin-paraalkylstyrene copolymer used in the present invention can be produced by halogenating a copolymer of isomonoolefin and paraalkylstyrene, and the halogenated isomonoolefin and paraalkylstyrene. The mixing ratio, polymerization rate, average molecular weight, polymerization form (block copolymer, random copolymer, etc.), viscosity, halogen atom, etc. are not particularly limited, depending on the physical properties required for the thermoplastic elastomer composition Can be arbitrarily selected. Examples of the isomonoolefin constituting the halogenated isomonoolefin-paraalkylstyrene copolymer include isobutylene, isopentene, isohexene, etc., but isobutylene is preferred. Examples of the paraalkyl styrene constituting the halogenated isomonoolefin-paraalkyl styrene copolymer include paramethyl styrene, paraethyl styrene, parapropyl styrene, parabutyl styrene and the like, and paramethyl styrene is preferable. Examples of the halogen constituting the halogenated isomonoolefin-paraalkylstyrene copolymer include fluorine, chlorine, bromine and iodine, with bromine being preferred. A particularly preferred halogenated isomonoolefin-paraalkylstyrene copolymer is a brominated isobutylene-paramethylstyrene copolymer.
Brominated isobutylene-paramethylstyrene copolymer has the formula (1)

Brominated isobutylene-paramethylstyrene copolymer having a repeating unit represented by formula (2)

It has a repeating unit represented by. Brominated isobutylene-paramethylstyrene copolymer is available from ExxonMobil Chemical Company under the trade name Exxpro ™.

  The blending amount of the halogenated isomonoolefin-paraalkylstyrene copolymer is preferably 10 to 150 parts by weight, more preferably 20 based on 100 parts by weight of the total amount of the ethylene-vinyl alcohol copolymer and the polyamide. It is -140 weight part, More preferably, it is 30-130 weight part. If the amount of the halogenated isomonoolefin-paraalkylstyrene copolymer is too small, the low-temperature durability is poor. On the other hand, if the amount is too large, the fluidity at the time of melting decreases and the film-forming property deteriorates.

  The halogenated isomonoolefin-paraalkylstyrene copolymer is preferably dynamically cross-linked by a cross-linking agent. By dynamically crosslinking, the matrix phase and the dispersed phase of the thermoplastic resin composition can be fixed. Dynamic crosslinking can be performed by melt-kneading a halogenated isomonoolefin-paraalkylstyrene copolymer together with a crosslinking agent.

Examples of the crosslinking agent used for dynamic crosslinking include zinc white, stearic acid, zinc stearate, magnesium oxide, m-phenylene bismaleimide, alkylphenol resin and its halide, secondary amine and the like. Secondary amines used as crosslinking agents include N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline, etc. Is mentioned. Among these, zinc white, stearic acid, zinc stearate, and N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine can be preferably used as a crosslinking agent for dynamic crosslinking.
The amount of the crosslinking agent is preferably 4 to 12 parts by weight, more preferably 6 to 9 parts by weight, based on 100 parts by weight of the halogenated isomonoolefin-paraalkylstyrene copolymer. If the amount of the crosslinking agent is too small, the dynamic crosslinking is insufficient, the fine dispersion of the halogenated isomonoolefin-paraalkylstyrene copolymer cannot be maintained, and the durability is lowered. On the other hand, if the amount of the crosslinking agent is too large, it may cause scorching during kneading and processing, or cause foreign matter in the film.

The dispersed phase preferably further comprises an elastomer having acid anhydride groups. By blending an elastomer having an acid anhydride group, durability at low temperatures and flexibility can be improved.
Examples of the elastomer having an acid anhydride group used in the present invention include maleic anhydride-modified ethylene-α-olefin copolymer elastomer, maleic anhydride-modified ethylene- (meth) acrylic acid copolymer elastomer, maleic anhydride-modified ethylene- ( Examples include meth) acrylic acid ester copolymer elastomers. Here, (meth) acrylic acid means acrylic acid and methacrylic acid.
Maleic anhydride-modified ethylene-α-olefin copolymer elastomer includes maleic anhydride-modified ethylene-propylene copolymer elastomer, maleic anhydride-modified ethylene-butene copolymer elastomer, maleic anhydride-modified ethylene-hexene copolymer elastomer, maleic anhydride Examples include acid-modified ethylene-octene copolymer elastomer.
Examples of maleic anhydride-modified ethylene- (meth) acrylic acid copolymer elastomers include maleic anhydride-modified ethylene-acrylic acid copolymer elastomers and maleic anhydride-modified ethylene-methacrylic acid copolymer elastomers.
Examples of maleic anhydride-modified ethylene- (meth) acrylic acid ester copolymer elastomers include maleic anhydride-modified ethylene-methyl acrylate copolymer elastomer, maleic anhydride-modified ethylene-ethyl acrylate copolymer elastomer, maleic anhydride-modified ethylene- Examples include methyl methacrylate copolymer elastomer and maleic anhydride-modified ethylene-ethyl methacrylate copolymer elastomer.
Particularly preferred elastomers having an acid anhydride group are maleic anhydride-modified ethylene-butene copolymer, maleic anhydride-modified ethylene-propylene copolymer, maleic anhydride-modified ethylene-octene copolymer, and the like. The maleic anhydride-modified ethylene-butene copolymer is commercially available, and can be obtained from Mitsui Chemicals, Inc. under the trade names of TAFMER (registered trademark) MH7010, MH7020, and maleic anhydride-modified ethylene-propylene copolymer. The polymer can be obtained from Mitsui Chemicals, Inc. under the trade names of TAFMER (registered trademark) MP0610 and MP0620, for example.

  When the thermoplastic resin composition includes an elastomer having an acid anhydride group, the blending amount of the elastomer having an acid anhydride group is preferably based on 100 parts by weight of the total amount of the ethylene-vinyl alcohol copolymer and the polyamide. Is 10 to 150 parts by weight, more preferably 20 to 140 parts by weight, still more preferably 30 to 130 parts by weight. If the blending amount of the elastomer is too small, the effect of improving the low temperature durability and flexibility cannot be sufficiently obtained. If the blending amount of the elastomer is too large, the fluidity at the time of melting is lowered and the film-forming property is deteriorated.

  The thermoplastic resin composition of the present invention comprises a resin other than an ethylene-vinyl alcohol copolymer and polyamide, a halogenated isomonoolefin-paraalkylstyrene copolymer, an elastomer other than an elastomer having an acid anhydride group, and various additives. May be included as long as the effects of the present invention are not impaired. Additives include cross-linking agents, anti-aging agents, plasticizers, processing aids (metal soaps, etc.), cross-linking accelerators, cross-linking accelerators, reinforcing agents (fillers), scorch inhibitors, peptizers, organic modifiers. A quality agent, a softening agent, a tackifier, etc. can be mentioned.

The thermoplastic resin composition of the present invention includes, but is not limited to, ethylene-vinyl alcohol copolymer, polyamide, halogenated isomonoolefin-paraalkylstyrene copolymer, phthalate ester, and, if necessary, acid. It can be produced by melt-kneading an elastomer having an anhydride group and other components at a temperature equal to or higher than the melting point of polyamide. When a crosslinking agent is added, the crosslinking agent may be mixed with the halogenated isomonoolefin-paraalkylstyrene copolymer in advance, or may be added before melt kneading, You may add in the middle. The melt kneading temperature is a temperature equal to or higher than the melting point of the polyamide, but is preferably a temperature 20 ° C. higher than the melting point of the polyamide, for example, 180 to 300 ° C. The melt kneading time is usually 1 to 10 minutes, preferably 1 to 5 minutes.
The thermoplastic resin composition of the present invention is preferably a continuous kneading of an ethylene-vinyl alcohol copolymer, a polyamide, and a halogenated isomonoolefin-paraalkylstyrene copolymer using a biaxial kneader, By kneading, a halogenated isomonoolefin-paraalkylstyrene copolymer is dispersed in a matrix phase composed of an ethylene-vinyl alcohol copolymer and a polyamide, and dynamically crosslinked.
More specifically, for example, a rubber compound is prepared by mixing a halogenated isomonoolefin-paraalkylstyrene copolymer, a crosslinking agent, and other additives as required at 60 to 150 ° C. Compound, polyamide, ethylene-vinyl alcohol copolymer and other resin or additive as required are charged into a twin-screw kneader with a set temperature of 220 to 250 ° C., and a halogenated isomonoolefin-paraalkylstyrene copolymer The thermoplastic resin composition of the present invention can be obtained by dispersing the coalescence and dynamically crosslinking.

The present invention is also an inner liner for a pneumatic tire comprising the thermoplastic resin composition.
The thermoplastic resin composition of the present invention can be formed into a film using an extruder with a T-die or an inflation molding machine. Since the film comprising the thermoplastic resin composition of the present invention is excellent in gas barrier properties and durability, it can be suitably used as an inner liner of a pneumatic tire.

The present invention is also a pneumatic tire including the inner liner.
More specifically, the pneumatic tire of the present invention is a pneumatic tire including a film of the thermoplastic resin composition as an inner liner. As a method for producing a pneumatic tire, a conventional method can be used. For example, the thermoplastic resin composition of the present invention is extruded into a film having a predetermined width and thickness, and this is adhered to a cylinder on a tire molding drum as an inner liner. On top of that, members used in normal tire production such as a carcass layer, a belt layer, a tread layer, and the like made of unvulcanized rubber are sequentially laminated and removed from the drum to obtain a green tire. Next, a desired pneumatic tire can be manufactured by heating and vulcanizing the green tire according to a conventional method.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited to a following example.

[raw materials]
The raw materials used in the following examples and comparative examples are as follows.

The following two types were used as ethylene-vinyl alcohol copolymers (hereinafter also referred to as “EVOH”).
Soarnol (registered trademark) E3808 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Soarnol (registered trademark) H4815B (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)

The following two types were used as polyamide.
Nylon 6: “UBE nylon” 1013B manufactured by Ube Industries, Ltd.
Nylon 6/66: “UBE nylon” 5023B manufactured by Ube Industries, Ltd.

As the halogenated isomonoolefin-paraalkylstyrene copolymer, the following was used.
Brominated isobutylene-paramethylstyrene copolymer rubber (hereinafter referred to as “Br-IPMS”): Exxpro ™ MDX89-4 manufactured by ExxonMobil Chemical Co.

The following were used as an elastomer having an acid anhydride group.
Acid-modified polyolefin elastomer: maleic anhydride-modified ethylene-butene copolymer “Tuffmer” (registered trademark) MH7010 manufactured by Mitsui Chemicals, Inc.

The following three types of phthalic acid esters were used.
Dimethyl phthalate: manufactured by Daihachi Chemical Industry Co., Ltd., molecular weight 194.2
Diethyl phthalate: manufactured by Daihachi Chemical Industry Co., Ltd., molecular weight 222.2
Dibutyl phthalate: manufactured by Daihachi Chemical Industry Co., Ltd., molecular weight 278.3

The following were used as a crosslinking agent.
Zinc oxide: 3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.

The following were used as anti-aging agents.
6PPD: Santoflex 13 (N- (1,3-dimethylbutyl) -N'-phenyl-1,4-phenylenediamine) manufactured by Flexsys

[Preparation of thermoplastic resin composition]
An ethylene-vinyl alcohol copolymer, polyamide, brominated isobutylene-paramethylstyrene copolymer rubber, phthalic acid ester, acid-modified polyolefin elastomer, cross-linking agent, and anti-aging agent are blended in the combinations shown in Tables 1 and 2. It is put into a cylinder of a kneading extruder (manufactured by Nippon Steel Co., Ltd.), transported to a kneading zone set at a temperature of 230 ° C. and a residence time of about 3 to 8 minutes, and melt kneaded. Extruded into a strand from the attached die. The obtained strand-shaped extrudate was pelletized with a resin pelletizer to obtain a pellet-shaped thermoplastic resin composition. About the obtained thermoplastic resin composition, the change rate of the air permeability coefficient by fatigue and low-temperature durability were evaluated. The evaluation results are shown in Tables 1 and 2.

[Change rate of air permeability coefficient due to fatigue]
Extrusion temperature C1 / C2 / C3 / C4 / die = 220/225/230/235 of the prepared pellet-shaped thermoplastic resin composition using a 40 mmφ single-screw extruder with a 550 mm width T die (Pura Giken Co., Ltd.) The film was formed into a film having an average thickness of 0.1 mm under extrusion conditions of / 235 ° C., a cooling roll temperature of 50 ° C., and a take-off speed of 4 m / min. The film was cut into a predetermined size and bonded to an unvulcanized rubber composition sheet (average thickness 2 mm) blended as shown in Table 3, and then vulcanized and bonded at 180 ° C. for 10 minutes to give a thermoplastic resin composition. A laminate of the product and the rubber composition was obtained. The laminate was cut into a width of 5 cm and repeatedly deformed 1 million times with a constant strain tester (manufactured by Ueshima Seisakusho Co., Ltd.). Before and after repeatedly applying deformation, the air permeability coefficient of the laminate was measured at a temperature of 23 ° C. and a humidity of 0% RH, and the change rate of the air permeability coefficient due to fatigue was calculated by the following equation.
Change rate of air permeability coefficient due to fatigue = Air permeability coefficient after deformation / Air permeability coefficient before deformation It was determined that the change rate of the air permeability coefficient due to fatigue was 2.0 or less as acceptable (with a suppression effect).

[Low temperature durability]
The prepared pellet-shaped thermoplastic resin composition was extruded at a extrusion temperature of C1 / C2 / C3 / C4 / die = 220/225/230 / using a 40 mmφ single-screw extruder with a 200 mm width T die (manufactured by Pla Giken Co., Ltd.). Formed into a sheet with an average thickness of 1.0 mm under extrusion conditions of 235/235 ° C., cooling roll temperature 50 ° C., take-off speed 1.0 m / min, punched out dumbbells (JIS No. 3) from the sheet, constant strain tester (stock) The product was set on a company Kamishima Seisakusho, 40% constant strain was repeatedly given at -40 ° C atmosphere, and the number of breaks was measured. Relative to the number of breaks in Comparative Example 1, the number of breaks 0.5 to 3.0 times the number of breaks in Comparative Example 1 is “good”, and the number of breaks from 0.2 to 0.5 times is “possible”. The number of breaks less than 0.2 times was determined as “impossible”, and the number of breaks greater than 3.0 times was determined as “excellent”. If the judgment is “good”, “good”, or “excellent”, when a film made of the thermoplastic resin composition is applied to a tire, the vehicle can run without any problem in durability.

  The thermoplastic resin composition of the present invention can be suitably used for producing an inner liner for a pneumatic tire.

Claims (8)

  A thermoplastic resin composition comprising a matrix phase containing an ethylene-vinyl alcohol copolymer and a polyamide and a dispersed phase containing a halogenated isomonoolefin-paraalkylstyrene copolymer, wherein the composition is ethylene-vinyl alcohol. A thermoplastic resin composition comprising 0.5 to 20 parts by weight of a phthalic acid ester having a molecular weight of 270 or less based on 100 parts by weight of a copolymer.   The thermoplastic resin composition according to claim 1, wherein the phthalate ester is dimethyl phthalate or diethyl phthalate.   The thermoplastic resin according to claim 1 or 2, wherein the weight ratio of the ethylene-vinyl alcohol copolymer and the polyamide contained in the matrix phase (ethylene-vinyl alcohol copolymer / polyamide) is 95/5 to 40/60. Composition.   The halogenated isomonoolefin-paraalkylstyrene copolymer is 10 to 150 parts by weight based on 100 parts by weight of the total amount of ethylene-vinyl alcohol copolymer and polyamide, according to any one of claims 1 to 3. The thermoplastic resin composition as described.   The thermoplastic resin composition according to any one of claims 1 to 4, wherein the dispersed phase further comprises an elastomer having an acid anhydride group.   The thermoplastic resin composition according to any one of claims 1 to 5, wherein the halogenated isomonoolefin-paraalkylstyrene copolymer is dynamically crosslinked by a crosslinking agent.   The inner liner for pneumatic tires which consists of a thermoplastic resin composition of any one of Claims 1-6.   A pneumatic tire including the inner liner according to claim 7.