JP7126387B2 - LAYER STRUCTURE, MOLDED BODY AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition, a layer structure, a molded article, and a method for producing the same.

A co-extrusion blow-molded container provided with a layer having fuel barrier properties is suitably used as a fuel container. As such a fuel barrier layer, for example, an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH") may be used.

Patent Document 1 describes a fuel container obtained by co-extrusion blow molding of a layer made of a barrier resin such as EVOH and a layer made of a thermoplastic resin.

On the other hand, Patent Document 2 describes a resin composition comprising EVOH and an acid-modified ethylene-α-olefin copolymer rubber and/or an acid-modified thermoplastic elastomer. An injection-molded article is disclosed, and it is said that both fuel barrier properties and low-temperature impact resistance can be achieved without using multilayer blow molding.

JP 2010-143644 A Japanese Patent Application Laid-Open No. 2005-68300

In general, a molded article made of EVOH alone is inferior in impact resistance. For this reason, in applications such as fuel containers, co-extrusion blow molding is preferably used in which a thermoplastic resin layer is provided to compensate for impact resistance (see Patent Document 1). On the other hand, in recent years, the range of applications has expanded, especially in applications such as fuel containers such as hydrogen tanks, where temperatures above the melting point of thermoplastic resin are sometimes used, and there are cases where conventional multi-layer containers cannot be used. It became so. In such a case, it was found that by using a single-layer barrier material as in Patent Document 2, it is possible to obtain a container that can withstand use at high temperatures.

However, using the resin composition of Patent Document 2, which consists of EVOH and an acid-modified ethylene-α-olefin copolymer rubber and/or an acid-modified thermoplastic elastomer, blow molding of a single layer results in a draw. The inventors have found that down tends to occur, blow molding with a single layer is difficult, and stable molding is difficult.

The present invention has been made based on the circumstances as described above, and an object of the present invention is to provide a resin composition containing EVOH, which has good moldability, particularly good blow moldability. An object of the present invention is to provide a layered structure and a molded article having at least one layer made of a resin composition, and a method for producing the molded article.

Embodiments of the present invention for solving the above problems are a resin composition, a layer structure, a molded article, and a method for producing a molded article described below.

[1] An ethylene-vinyl alcohol copolymer containing an ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) having a modifying group capable of reacting with the ethylene-vinyl alcohol copolymer (A) The mass ratio (A/B) between (A) and the thermoplastic resin (B) is 50/50 to 90/10, and the ethylene unit content of the ethylene-vinyl alcohol copolymer (A) is 10 to 35 mol. % and the melt tension at 220° C. is 40 to 130 mN.
[2] The thermoplastic resin (B) is a thermoplastic elastomer having a modifying group capable of reacting with the ethylene-vinyl alcohol copolymer (A) or a modifying group capable of reacting with the ethylene-vinyl alcohol copolymer (A). The resin composition of [1], which is an α-olefin polymer having
[3] The resin composition of [1] or [2], wherein the thermoplastic resin (B) is a resin modified with an unsaturated carboxylic acid or a derivative thereof.
[4] The resin composition according to any one of [1] to [3], wherein the thermoplastic resin (B) has an acid value of 1 to 20 mgKOH/g.
[5] A single-layer or multi-layer structure having at least one layer made of the resin composition according to any one of [1] to [4].
[6] A molded article having at least one layer made of the resin composition according to any one of [1] to [4].
[7] The molded article of [6], which is a blow-molded container.
[8] The compact of [6], which is a fuel container.
[9] A method for producing a molded article, comprising blow molding using the resin composition according to any one of [1] to [4].

According to the present invention, there are provided a resin composition containing an ethylene-vinyl alcohol copolymer and having good moldability, a layer structure having at least one layer comprising the above resin composition, and a molded article. , and a method for producing the molded article.

<Resin composition>
A resin composition according to one embodiment of the present invention comprises an ethylene-vinyl alcohol copolymer (A) (hereinafter sometimes abbreviated as “EVOH (A)”), and a modifying group capable of reacting with EVOH (A) Contains a thermoplastic resin (B) (hereinafter sometimes abbreviated as “thermoplastic resin (B)”) having In the resin composition of the present invention, the mass ratio (A/B) of EVOH (A) and thermoplastic resin (B) is 50/50 to 90/10. The ethylene unit content of EVOH (A) is 10 to 35 mol %. The melt tension at 220° C. of the resin composition of the present invention is 40-130 mN. The resin composition of the present invention has good melt moldability because the melt tension is within the above range. Specifically, since the resin composition of the present invention has a melt tension within the above range, drawdown during blow molding is suppressed, and single layer blow molding can be easily performed. In the resin composition of the present invention, although it is not clear, some reaction such as cross-linking occurs between the EVOH (A) and the thermoplastic resin (B) in an appropriate mass ratio, thereby increasing the melt tension. It is speculated that

(EVOH (A))
EVOH (A) is a copolymer having ethylene units and vinyl alcohol units and having an ethylene unit content of 10 to 35 mol %. EVOH (A) is usually obtained by saponifying an ethylene-vinyl ester copolymer. Production and saponification of the ethylene-vinyl ester copolymer can be carried out by known methods. Vinyl esters are typically vinyl acetate, but other vinyl fatty acids such as vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate and vinyl versatate. It may be an ester.

The lower limit of the ethylene unit content of EVOH (A) is 10 mol%, preferably 15 mol%, more preferably 20 mol%, and may be 23 mol%. The upper limit of the ethylene unit content of EVOH (A) is 35 mol%, preferably 30 mol%, more preferably 28 mol%, even more preferably 26%. If the ethylene unit content is less than 10 mol %, the thermal stability tends to be lowered. On the other hand, when the ethylene unit content exceeds 35 mol %, the gas barrier properties and melt tension tend to decrease. In addition, in this specification, "gas barrier property" is evaluated based on the measurement result of oxygen barrier property.

The lower limit of the degree of saponification of EVOH (A) is preferably 90 mol%, more preferably 95 mol%, even more preferably 99 mol%. When the degree of saponification of EVOH (A) is 90 mol % or more, gas barrier properties, thermal stability, moisture resistance, etc. of the resin composition of the present invention tend to be improved. Moreover, the upper limit of the degree of saponification may be 100 mol%, 99.97 mol%, or 99.94 mol%.

EVOH (A) may have units derived from monomers other than ethylene and vinyl ester as long as the object of the present invention is not impaired. The units derived from other monomers are monomer units other than ethylene units, vinyl ester units and vinyl alcohol units. When EVOH (A) has units derived from the other monomer, the upper limit of the content of units derived from the other monomer to all structural units of EVOH (A) is preferably 30 mol%, and 20 mol. % is more preferred, 10 mol % is even more preferred, 5 mol % is even more preferred, and 1 mol % is even more preferred. When EVOH (A) has units derived from the other monomers, the lower limit of the content may be 0.05 mol % or 0.10 mol %.

The above other monomers include, for example, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid and itaconic acid, or their anhydrides, salts, mono- or dialkyl esters; acrylonitrile, nitriles such as methacrylonitrile; Amides such as methacrylamide; olefin sulfonic acids such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, or salts thereof; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, γ-methacryl Vinylsilane compounds such as oxypropylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like.

The unit derived from the other monomer may be at least one of a structural unit (I) represented by the following formula (I) and a structural unit (II) represented by the following formula (II). .

In structural unit (I) and structural unit (II) above, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a C 1-10 It represents an aliphatic hydrocarbon group, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, or a hydroxyl group. Also, pairs of R ¹ , R ² and R ³ , R ⁴ and R ⁵ , and R ⁶ and R ⁷ may be bonded. Some or all of the hydrogen atoms of the aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms and the aromatic hydrocarbon group having 6 to 10 carbon atoms are hydroxyl groups, It may be substituted with an alkoxy group, a carboxyl group or a halogen atom.

When EVOH (A) has the above-mentioned structural unit (I) or (II), the flexibility and processability of the resin composition are improved, and the obtained molded article and layered structure have good stretchability, thermoformability, etc. tend to be

In the structural unit (I) or (II), the aliphatic hydrocarbon group having 1 to 10 carbon atoms includes an alkyl group, an alkenyl group, and the like, and the alicyclic hydrocarbon group having 3 to 10 carbon atoms is A cycloalkyl group, a cycloalkenyl group and the like can be mentioned, and an aromatic hydrocarbon group having 6 to 10 carbon atoms can be exemplified by a phenyl group and the like.

In the structural unit (I), R ¹ , R ² and R ³ are preferably each independently a hydrogen atom, a methyl group, an ethyl group, a hydroxyl group, a hydroxymethyl group or a hydroxyethyl group. A hydrogen atom, a methyl group, a hydroxyl group, or a hydroxymethyl group is more preferable from the viewpoint of further improving the stretchability and thermoformability of the layer structure and the like.

The method for incorporating the structural unit (I) into EVOH (A) is not particularly limited. For example, in the polymerization of ethylene and vinyl ester, a monomer derived from the structural unit (I) is copolymerized methods and the like. Examples of monomers derived from this structural unit (I) include alkenes such as propylene, butylene, pentene and hexene; 3-hydroxy-1-propene, 3-acyloxy-1-propene, 3-acyloxy-1- Butene, 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-hydroxy-1-butene, 4-acyloxy-3-hydroxy-1-butene, 3-acyloxy-4- methyl-1-butene, 4-acyloxy-2-methyl-1-butene, 4-acyloxy-3-methyl-1-butene, 3,4-diacyloxy-2-methyl-1-butene, 4-hydroxy-1- Pentene, 5-hydroxy-1-pentene, 4,5-dihydroxy-1-pentene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diacyloxy-1-pentene, 4-hydroxy- 3-methyl-1-pentene, 5-hydroxy-3-methyl-1-pentene, 4,5-dihydroxy-3-methyl-1-pentene, 5,6-dihydroxy-1-hexene, 4-hydroxy-1- hexene, 5-hydroxy-1-hexene, 6-hydroxy-1-hexene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy-1-hexene, 5,6-diacyloxy-1- Examples include alkenes having a hydroxyl group or an ester group such as hexene. Among them, propylene, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy- 1-butene and 3,4-diacyloxy-1-butene are preferred. Incidentally, "acyloxy" is preferably acetoxy, specifically 3-acetoxy-1-propene, 3-acetoxy-1-butene, 4-acetoxy-1-butene and 3,4-diacetoxy-1-butene is preferred. In the case of an alkene having an ester, it is induced to the above structural unit (I) during the saponification reaction.

In structural unit (II) above, both R ⁴ and R ⁵ are preferably hydrogen atoms. More preferably, both R ⁴ and R ⁵ are hydrogen atoms, one of R ⁶ and R ⁷ is a C 1-10 aliphatic hydrocarbon group, and the other is a hydrogen atom. The aliphatic hydrocarbon groups are preferably alkyl groups and alkenyl groups. From the viewpoint of placing particular importance on the gas barrier properties of the resulting layered structure, it is more preferable that one of R ⁶ and R ⁷ is a methyl group or an ethyl group, and the other is a hydrogen atom. It is more preferable that one of R ⁶ and R ⁷ is a substituent represented by (CH ₂ ) _h OH (where h is an integer of 1 to 8) and the other is a hydrogen atom. In the substituent represented by (CH ₂ ) _h OH, h is preferably an integer of 1 to 4, more preferably 1 or 2, even more preferably 1.

The method for incorporating the structural unit (II) into EVOH (A) is not particularly limited, and a method of incorporating by reacting EVOH (A) obtained by a saponification reaction with a monovalent epoxy compound, or the like is used. . As the monovalent epoxy compound, compounds represented by the following formulas (i) to (vii) are preferably used.

In the above formulas (i) to (vii), R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms (alkyl group, alkenyl group, etc.), an alicyclic hydrocarbon group having 3 to 10 carbon atoms (cycloalkyl group, cycloalkenyl group, etc.), or an aliphatic hydrocarbon group having 6 to 10 carbon atoms (phenyl group, etc.). i, j, k, p and q each independently represents an integer of 1 to 8; However, when R ¹¹ is a hydrogen atom, R ¹² has a substituent other than a hydrogen atom.

Examples of monovalent epoxy compounds represented by formula (i) include epoxyethane (ethylene oxide), epoxypropane, 1,2-epoxybutane, 2,3-epoxybutane, 3-methyl-1,2-epoxy, Butane, 1,2-epoxypentane, 3-methyl-1,2-epoxypentane, 1,2-epoxyhexane, 2,3-epoxyhexane, 3,4-epoxyhexane, 3-methyl-1,2-epoxy Hexane, 3-methyl-1,2-epoxyheptane, 4-methyl-1,2-epoxyheptane, 1,2-epoxyoctane, 2,3-epoxyoctane, 1,2-epoxynonane, 2,3-epoxy nonane, 1,2-epoxydecane, 1,2-epoxydodecane, epoxyethylbenzene, 1-phenyl-1,2-epoxypropane, 3-phenyl-1,2-epoxypropane and the like. Examples of the monovalent epoxy compound represented by formula (ii) include various alkyl glycidyl ethers. Examples of the monovalent epoxy compound represented by formula (iii) include various alkylene glycol monoglycidyl ethers. Examples of the monovalent epoxy compound represented by formula (iv) include various alkenyl glycidyl ethers. Examples of the monovalent epoxy compound represented by formula (v) include various epoxyalkanols such as glycidol. Examples of the monovalent epoxy compound represented by the formula (vi) include various epoxycycloalkanes. Examples of the monovalent epoxy compound represented by the above formula (vii) include various epoxycycloalkenes.

Among the above monovalent epoxy compounds, epoxy compounds having 2 to 8 carbon atoms are preferred. In particular, from the viewpoints of ease of handling and reactivity of the compound, the number of carbon atoms in the monovalent epoxy compound is more preferably 2-6, more preferably 2-4. Moreover, it is particularly preferable that the monovalent epoxy compound is a compound represented by the above formula (i) or formula (ii). Specifically, 1,2-epoxybutane, 2,3-epoxybutane, epoxy Propane, epoxyethane or glycidol are preferred, with epoxypropane or glycidol being more preferred.

The melting point of EVOH (A) is not particularly limited, but the lower limit is preferably 160°C, more preferably 170°C, still more preferably 180°C, and particularly preferably 190°C or 194°C. When the melting point of EVOH (A) is 160° C. or higher, melt moldability, particularly blow moldability can be enhanced. On the other hand, the upper limit of this melting point is preferably 240°C, more preferably 220°C, and even more preferably 200°C. When the melting point of EVOH (A) is within the above range, melt moldability, particularly blow moldability, is further enhanced.

EVOH (A) may be used alone or in combination of two or more.

The lower limit of the content of EVOH (A) in the resin composition of the present invention is preferably 50% by mass, more preferably 55% by mass, and even more preferably 60% by mass. On the other hand, the upper limit of the content of EVOH (A) in the resin composition of the present invention is preferably 90% by mass, more preferably 85% by mass, even more preferably 80% by mass. By setting the content of EVOH (A) within the above range, there is a tendency that melt tension is further increased, and moldability, particularly blow moldability, is further improved. In addition, gas barrier properties can be enhanced by adjusting the content of EVOH (A) to be equal to or higher than the above lower limit.

(Thermoplastic resin (B))
The thermoplastic resin (B) has a modifying group capable of reacting with EVOH (A) (hereinafter sometimes abbreviated as "modifying group"). The modifying group is usually a group capable of reacting with the hydroxyl group of EVOH (A), and examples thereof include acidic groups (acidic modifying groups), epoxy groups, amino groups, and halogens. Among them, an acidic group is preferred. Examples of acidic groups include a carboxy group (--COOH) and a sulfo group (--SO ₃ H). Moreover, an acid anhydride group shall also be contained in an acidic group. An acid anhydride group is a group obtained by dehydration condensation of two acidic groups, and examples thereof include a carboxylic acid anhydride group represented by -CO-O-CO-. Among the acidic groups, a carboxy group and a carboxylic acid anhydride group are preferred.

Among thermoplastic resins (B), thermoplastic resins modified with unsaturated carboxylic acids or derivatives thereof are more preferred. In this case, the thermoplastic resin (B) will have a carboxy group or a carboxylic anhydride group derived from an unsaturated carboxylic acid or a derivative thereof as a modifying group. Examples of unsaturated carboxylic acids or derivatives thereof include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester. be done. Among unsaturated carboxylic acids or derivatives thereof, maleic anhydride is more preferable from the viewpoint of reactivity. That is, among thermoplastic resins modified with unsaturated carboxylic acids or derivatives thereof, maleic anhydride-modified products are preferred.

The lower limit of the acid value of the thermoplastic resin (B) is preferably 1 mgKOH/g, more preferably 3 mgKOH/g, still more preferably 5 mgKOH/g, even more preferably 7 mgKOH/g, and particularly preferably 10 mgKOH/g. On the other hand, the upper limit of the acid value of the thermoplastic resin (B) is preferably 20 mgKOH/g, more preferably 16 mgKOH/g, even more preferably 14 mgKOH/g. When the thermoplastic resin (B) has an acid value within the above range, the melt tension tends to be higher, and moldability, particularly blow moldability, tends to be higher. The acid value is a value measured by changing the solvent for dissolving the resin to be measured to xylene in the neutralization titration method described in JIS K0070:1992.

The thermoplastic resin (B) is preferably an α-olefin polymer having a modifying group or a thermoplastic elastomer having a modifying group, more preferably an α-olefin polymer having a modifying group. Group-containing α-olefin copolymers are more preferred. The α-olefin polymer is a polymer containing α-olefin as a monomer, and examples include homopolymers of α-olefin, copolymers of two or more α-olefins, and and copolymers with other monomers.

The α-olefin copolymer having a modifying group (modified α-olefin copolymer) is not particularly limited, and may be an ethylene-propylene copolymer having a modifying group, an ethylene-butene copolymer having a modifying group, a modifying group and a butylene-ethylene copolymer having a modifying group. These may be used alone or in combination of two or more. Among them, from the viewpoint of excellent flexibility and improved bending resistance of the molded article and layer structure obtained from the resin composition of the present invention, an ethylene-propylene copolymer having a modifying group and ethylene-butene having a modifying group Copolymers are preferred. The α-olefin copolymer having a modifying group is preferably an acid-modified α-olefin copolymer, more preferably a maleic anhydride-modified α-olefin copolymer.

The α-olefin polymer having a modifying group may be a polymer having rubber elasticity (elastomer) or may be a polymer having no rubber elasticity. Also, an α-olefin polymer having a modifying group can be produced by a known method. A commercially available α-olefin polymer having a modifying group may be used.

Examples of the thermoplastic elastomer having a modifying group (modified thermoplastic elastomer) include a modified polyester thermoplastic elastomer, a modified polystyrene thermoplastic elastomer, a modified polyurethane thermoplastic elastomer, a modified polyolefin thermoplastic elastomer, and a modified polyamide thermoplastic elastomer. Elastomers and the like can be mentioned.

Here, the polyester-based thermoplastic elastomer is a multi-block copolymer having polyester as a hard segment in the molecule and polyether or polyester having a low glass transition temperature (Tg) as a soft segment. Polyester-based thermoplastic elastomers can be classified into the following types depending on the difference in molecular structure, and the polyester/polyether type and the polyester/polyester type are the mainstream.
(1) Polyester-polyether type In general, it is a thermoplastic elastomer using an aromatic crystalline polyester as a hard segment and a polyether as a soft segment.
(2) Polyester-polyester type This is a thermoplastic elastomer using an aromatic crystalline polyester as a hard segment and an aliphatic polyester as a soft segment.
(3) Liquid Crystalline Thermoplastic elastomer using rigid liquid crystal molecules as hard segments and aliphatic polyester as soft segments.

Examples of the polyester segment include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; succinic acid and aliphatic dicarboxylic acids such as adipic acid. Formed from a dicarboxylic acid component and a diol component such as an aliphatic diol such as ethylene glycol, 1,2-propylene glycol or 1,4-butanediol; or an alicyclic diol such as cyclohexane-1,4-dimethanol A polyester segment may be mentioned. Examples of the polyether segment include aliphatic polyether segments such as polyethylene glycol, polypropylene glycol and polybutylene glycol.

The modified polyester-based thermoplastic elastomer means the polyester-based thermoplastic elastomer having a modifying group in the polyester-based thermoplastic elastomer described above, and is more preferably a maleic anhydride-modified polyester-based thermoplastic elastomer.

Here, the polystyrene-based thermoplastic elastomer usually comprises a styrene-based polymer block (Hb) as a hard segment and a conjugated diene-based polymer block or its hydrogenated block (Sb) as a soft segment. The structure of this styrene-based thermoplastic elastomer includes a diblock structure represented by Hb--Sb, a triblock structure represented by Hb--Sb--Hb or Sb--Hb--Sb, and a structure represented by Hb--Sb--Hb--Sb. or a polyblock structure in which a total of 5 or more Hb and Sb are linearly bonded.

Styrenic monomers used in the styrenic polymer block (Hb) include styrene and derivatives thereof, such as styrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4 -t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochloro Styrenes such as styrene, dichlorostyrene, methoxystyrene, and t-butoxystyrene; Vinyl group-containing aromatic compounds such as vinylnaphthalenes such as 1-vinylnaphthalene and 2-vinylnaphthalene; Vinylene group-containing aromatic compounds such as indene and acenaphthylene compound and the like. Among them, styrene is preferred. Only one type of styrene-based monomer may be used, or two or more types may be used.

Examples of conjugated diene compounds used in the conjugated diene-based polymer block or its hydrogenated block (Sb) include butadiene, isoprene, 2,3-dimethylbutadiene, pentadiene, and hexadiene. Among them, butadiene is preferred. The number of conjugated diene compounds may be one, or two or more. In addition, other comonomers such as ethylene, propylene, butylene, styrene can also be copolymerized. Also, the conjugated diene-based polymer block may be a partially or completely hydrogenated hydrogenated product.

The modified polystyrene-based thermoplastic elastomer means the above-mentioned polystyrene-based thermoplastic elastomer having a modifying group, and specific examples thereof include modified styrene-isoprene diblock copolymers, modified styrene-butadiene diblock copolymers, modified styrene-isoprene-styrene triblock copolymers, modified styrene-butadiene/isoprene-styrene triblock copolymers, modified styrene-butadiene-styrene triblock copolymers and hydrogenated products thereof. Among them, hydrogenated modified styrene-isoprene diblock copolymer, hydrogenated modified styrene-butadiene diblock copolymer, hydrogenated modified styrene-isoprene-styrene triblock copolymer, modified styrene-butadiene / Hydrogenated isoprene-styrene triblock copolymer and hydrogenated modified styrene-butadiene-styrene triblock copolymer are preferred. More preferably, the modified polystyrene-based thermoplastic elastomer is a maleic anhydride-modified polystyrene-based thermoplastic elastomer.

Here, the polyurethane-based thermoplastic elastomer is a linear type having (1) a hard segment obtained by reaction of a short-chain glycol and isocyanate and (2) a soft segment obtained by reaction of a long-chain glycol and isocyanate. is a multi-block copolymer of Here, polyurethane is a general term for compounds having a urethane bond (--NHCOO--) obtained by polyaddition reaction (urethanization reaction) between isocyanate (--NCO) and alcohol (--OH).

The modified polyurethane thermoplastic elastomer means the above-described polyurethane thermoplastic elastomer having a modifying group, and maleic anhydride-modified polyurethane thermoplastic elastomer is more preferable.

Here, the polyolefin-based thermoplastic elastomer includes thermoplastic elastomers having polyolefin blocks such as polypropylene and polyethylene as hard segments and rubber blocks such as ethylene-propylene-diene copolymer as soft segments. Polyolefin-based thermoplastic elastomers are classified into a blend type and an implant type.

Modified polyolefin-based thermoplastic elastomer means the above-mentioned polyolefin-based thermoplastic elastomer having a modifying group, and examples thereof include maleic anhydride-modified ethylene-butene-1 copolymer and maleic anhydride-modified ethylene-propylene copolymer. , halogenated butyl rubber, modified polypropylene, modified polyethylene, etc., and maleic anhydride-modified polyolefin thermoplastic elastomer is more preferable.

Here, the polyamide-based thermoplastic elastomer is a multi-block copolymer using polyamide as a hard segment and polyether or polyester having a low Tg as a soft segment. The polyamide component constituting the hard segment is selected from nylon 6, 66, 610, 11, 12 and the like, with nylon 6 and nylon 12 being the main components. Long-chain polyols such as polyether diols and polyester diols are used as soft segment constituents. Representative examples of polyether polyols include diol poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, etc. Representative examples of polyester polyols include poly(ethylene adipate) glycol, poly(butylene-1,4 - adipate) glycol and the like.

The modified polyamide-based thermoplastic elastomer means the above-described polyamide-based thermoplastic elastomer having a modifying group, and is more preferably a maleic anhydride-modified polyamide-based thermoplastic elastomer.

As the modified thermoplastic elastomer (thermoplastic elastomer having a modifying group), an acid-modified thermoplastic elastomer is preferable, and a maleic anhydride-modified thermoplastic elastomer is more preferable. A thermoplastic elastomer having a modifying group can be produced by a known method. A commercially available thermoplastic elastomer having a modifying group may be used.

The thermoplastic resin (B) may be used singly or in combination of two or more.

The lower limit of the content of the thermoplastic resin (B) in the resin composition of the present invention is preferably 10% by mass, more preferably 15% by mass, and even more preferably 20% by mass. On the other hand, the upper limit of the content of the thermoplastic resin (B) in the resin composition of the present invention is preferably 50% by mass, more preferably 45% by mass, and even more preferably 40% by mass. By setting the content of the thermoplastic resin (B) within the above range, the melt tension tends to increase, and moldability, particularly blow moldability, tends to increase.

(Mixing ratio, etc.)
The lower limit of the mass ratio (A/B) between EVOH (A) and thermoplastic resin (B) is 50/50, preferably 55/45, more preferably 60/40. On the other hand, the upper limit of the mass ratio (A/B) of EVOH (A) and thermoplastic resin (B) is 90/10, preferably 85/15, more preferably 80/20. By setting the mixing ratio of the EVOH (A) and the thermoplastic resin (B) within the above range, the melt tension can be increased, good blow moldability can be exhibited, and gas barrier properties can be in a good state. can.

The lower limit of the total content of EVOH (A) and thermoplastic resin (B) in the resin composition of the present invention is preferably 90% by mass, more preferably 99% by mass, 99.9% by mass or 99.99% by mass. may be even more preferable. By increasing the total content of EVOH (A) and thermoplastic resin (B), better moldability, gas barrier properties, etc. may be exhibited.

(Other additives)
The resin composition of the present invention contains a resin different from EVOH (A) and the thermoplastic resin (B), a metal salt, an acid, a boron compound, a plasticizer, a filler, a blocking agent, as long as the effects of the present invention are not impaired. May contain other components such as inhibitors, lubricants, stabilizers, surfactants, colorants, UV absorbers, antistatic agents, desiccants, cross-linking agents, fillers, reinforcing materials such as various fibers, etc. . Among them, it is preferable to contain a metal salt and an acid from the viewpoint of thermal stability and adhesiveness with other resins.

As the metal salt, an alkali metal salt is preferred from the viewpoint of enhancing interlayer adhesion, and an alkaline earth metal salt is preferred from the viewpoint of thermal stability. When the resin composition of the present invention contains a metal salt, the content is preferably 1 ppm or more, more preferably 5 ppm or more, still more preferably 10 ppm or more, and particularly preferably 20 ppm or more in terms of metal atoms of the metal salt. The content of the metal salt is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, even more preferably 1,000 ppm or less, and particularly preferably 500 ppm or less, relative to the resin composition in terms of metal atoms of the metal salt. When the content of the metal salt is within the above range, the thermal stability during recycling tends to be improved while maintaining good interlayer adhesion.

As the acid, a carboxylic acid compound or a phosphoric acid compound is preferable from the viewpoint of enhancing thermal stability during melt molding. When the resin composition of the present invention contains a carboxylic acid compound, the content of the carboxylic acid is preferably 1 ppm or more, more preferably 10 ppm or more, and even more preferably 50 ppm or more, relative to the resin composition. The carboxylic acid content is preferably 10000 ppm or less, more preferably 1000 ppm or less, and even more preferably 500 ppm or less. Moreover, when a phosphoric acid compound is included, the content of the phosphoric acid compound is preferably 1 ppm or more, more preferably 10 ppm or more, and still more preferably 30 ppm or more, relative to the resin composition. On the other hand, the content of the phosphoric acid compound is preferably 10000 ppm or less, more preferably 1000 ppm or less, and even more preferably 300 ppm or less. When the resin composition of the present invention contains the carboxylic acid compound or the phosphoric acid compound within the above range, the thermal stability during melt molding tends to be improved.

When the resin composition of the present invention contains the boron compound, the content thereof is preferably 1 ppm or more, more preferably 10 ppm or more, and even more preferably 50 ppm or more, relative to the resin composition. Also, the content of the boron compound is preferably 2000 ppm or less, more preferably 1000 ppm or less, and even more preferably 500 ppm or less. When the content of the boron compound is within the above range, the thermal stability during melt molding tends to be improved.

(Physical properties of resin composition)
In the resin composition of the present invention, the lower limit of the melt tension at 220°C is 40 mN, preferably 50 mN, more preferably 60 mN. On the other hand, the upper limit of the melt tension is 130 mN, preferably 120 mN, more preferably 110 mN. When the melt tension at 220° C. of the resin composition of the present invention is within the above range, good moldability is exhibited, and in particular, blow molding of a single layer can be easily performed.

In addition, "melt tension" is measured by extruding a resin composition in a molten state at 220 ° C. from a capillary at a constant speed using a test apparatus (capillary die) conforming to JIS K7199: 1999, and withdrawing it at a predetermined speed. It is a value obtained by measuring the tension when Specifically, using Toyo Seiki Seisakusho's "Capilograph 1D", the measurement temperature is 220 ° C., the capillary diameter is 1 mm, the length is 10 mm, the piston speed is 15 mm / min, and the take-up speed is 7.5 m / min. can be

The melt tension of the resin composition of the present invention can be adjusted by the ethylene unit content of EVOH (A), the mixing ratio of EVOH (A) and thermoplastic resin (B), kneading conditions, and the like. Specific methods for adjusting the kneading conditions include, for example, when using a single-screw extruder, adjusting the resin residence time by adjusting the shape and groove depth of the screw, adjusting the shear viscosity, and the like. be done. As the screw shape, for example, a full-flight screw, a barrier screw, or the like can be used. In addition, in order to adjust the kneading strength, a screw having a shape such as Maddock or Dulmage may be used. Additionally, the screw speed may be adjusted to increase the shear rate. Moreover, a twin-screw extruder may be used from the viewpoint of easily changing the screw shape. In the case of using a twin-screw extruder, a method of adjusting the length of the kneading disk can be used to adjust the kneading strength. The melt tension tends to be increased by performing sufficient kneading, such as by increasing the kneading strength.

The resin composition of the present invention is usually a dried product, and although its shape is not particularly limited, it is usually in the form of pellets or powder. The water content of the resin composition of the present invention may be, for example, 10% by mass or less, 1% by mass or less, or 0.1% by mass or less. In addition, all resin components refer to EVOH (A), thermoplastic resin (B), and other resins as optional components.

The resin composition of the present invention has good moldability, particularly excellent moldability in blow molding of a single layer, and also has good gas barrier properties and mechanical properties evaluated by elongation at break and the like. Therefore, the resin composition of the present invention can be suitably used as a melt molding material such as a packaging material, particularly as a blow molding material.

(Method for producing resin composition)
The method for producing the resin composition of the present invention is not particularly limited, but for example, it is produced by sufficiently mixing or kneading EVOH (A) and thermoplastic resin (B) under melting conditions.

Mixing or kneading under melt conditions can be carried out using known mixing or kneading equipment such as kneader ruders, extruders, mixing rolls, Banbury mixers and the like. The temperature during mixing or kneading may be appropriately adjusted according to the melting points of the EVOH (A) and thermoplastic resin (B) used, but a temperature within the temperature range of 160° C. or higher and 300° C. or lower is usually adopted. 180° C. or higher and 290° C. or lower, or 200° C. or higher and 280° C. or lower.

When the resin composition of the present invention contains a phosphoric acid compound, a carboxylic acid, a boron compound, or the like, the method of incorporating these is not particularly limited. For example, when preparing pellets of the resin composition of the present invention, a method of adding to the composition and kneading is preferably employed. The method of addition is also not particularly limited, but a method of adding as a dry powder, a method of adding in the form of a paste impregnated with a solvent, a method of adding in a state of being suspended in a liquid, a method of dissolving in a solvent and adding as a solution. , a method of immersion in a solution, and the like. Among them, from the viewpoint of uniform dispersion, a method of dissolving in a solvent and adding as a solution or a method of immersing in a solution is preferable. Although the solvent is not particularly limited, water is preferably used from the viewpoints of solubility of additives, cost, ease of handling, safety in the working environment, and the like.

<Layered structure>
A layer structure according to one embodiment of the present invention has at least one layer comprising the resin composition of the present invention. The layer structure may be a single layer or multiple layers of two or more layers.

When the layer structure of the present invention is a single layer, the layer structure is formed only from the resin composition of the present invention. Moreover, when the layer structure is multi-layered, it usually has a layer formed from the resin composition of the present invention and a layer composed of other components. The layer structure may be a sheet, film, or the like, or may be molded into other shapes.

Examples of the layer composed of other components include thermoplastic resins other than EVOH (A) and thermoplastic resin (B), paper, woven fabric, non-woven fabric, metal cotton strips, woody surfaces, and thermoplastic resins. Among them, other thermoplastic resin layers are preferable. The layer structure of the layer structure is not particularly limited, and when a layer made of the resin composition of the present invention is represented by E, an adhesive layer by Ad, and a layer obtained from another thermoplastic resin by T, T/E/T , E/Ad/T, and T/Ad/E/Ad/T. Each of these layers may be a single layer or multiple layers.

When the layer structure of the present invention is a multilayer structure, the manufacturing method thereof includes, for example, a method of melt extruding a thermoplastic resin into a molded article (film, sheet, etc.) obtained from the resin composition of the present invention. A method of co-extrusion of the resin composition of the present invention and another thermoplastic resin, a method of co-injecting the resin composition of the present invention and another thermoplastic resin, a layer obtained from the resin composition of the present invention and other heat A method of laminating a plastic resin layer using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester-based compound, or the like can be used.

Other thermoplastic resins include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, and propylene-α-olefin. (α-olefins with 4 to 20 carbon atoms) copolymers, homopolymers of olefins such as polybutene and polypentene or their copolymers, polyesters such as polyethylene terephthalate, polyester elastomers, polyamides such as nylon-6 and nylon-66, polystyrene , polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyurethane, polycarbonate, chlorinated polyethylene, chlorinated polypropylene, and the like. Among them, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene and polyester are preferably used.

The adhesive layer is not particularly limited as long as it has adhesiveness to the layer of the resin composition of the present invention and the layer of another thermoplastic resin, but an adhesive resin containing carboxylic acid-modified polyolefin is preferable. As the carboxylic acid-modified polyolefin, a modified olefin-based polymer containing carboxyl groups obtained by chemically bonding an ethylenically unsaturated carboxylic acid, its ester, or its anhydride to an olefin-based polymer can be preferably used. can. Here, the olefinic polymer means polyolefins such as polyethylene, linear low-density polyethylene, polypropylene and polybutene, and copolymers of olefins and other monomers. Among them, linear low-density polyethylene, ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer are preferable, and linear low-density polyethylene and ethylene-vinyl acetate copolymer are particularly preferable.

When the layer structure of the present invention is a single-layer film, it can be produced by the same method as for conventional single-layer films. Among them, a cast molding step of melt extruding the resin composition of the present invention on a casting roll, and / or a step of stretching an unstretched film obtained from the resin composition of the present invention (uniaxial stretching step, sequential biaxial step, simultaneous A method including a biaxial stretching step and an inflation molding step is preferred.

<Molded body>
A molded article according to one embodiment of the present invention has at least one layer comprising the resin composition of the present invention. Such a molded article may be a molded article composed only of the resin composition of the present invention. Examples of the molded article include films, sheets, tubes, bags, containers, and the like. Note that the layer structure and the molded body may overlap in terms of form, but the layer structure focuses on the layer structure, and the molded body focuses on the presence or absence of molding.

The molded article of the present invention can usually be produced by melt molding the resin composition of the present invention. The melt molding method includes, for example, extrusion molding, cast molding, inflation extrusion molding, blow molding, melt spinning, injection molding, injection blow molding, etc. Among them, blow molding can be preferably employed. The melt-molding temperature varies depending on the melting point of EVOH (A) and the like, but is preferably about 150 to 270°C. These moldings can be pulverized and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets and the like.

The molded article of the present invention may be multi-layered or single-layered, but a single-layered blow-molded article is particularly preferred. As described above, when a conventional resin composition containing EVOH is used for blow molding, drawdown tends to occur during parison molding, making blow molding difficult. This drawdown tends to occur remarkably when blow molding is performed using a conventional resin composition containing EVOH. In contrast, the resin composition of the present invention suppresses the occurrence of drawdown. Therefore, a single-layer blow-molded article using the resin composition of the present invention has good moldability and can exhibit good gas barrier properties. In addition, the molded article is also excellent in mechanical properties evaluated by elongation at break and the like. Furthermore, a single-layer molded article using the resin composition of the present invention can withstand use at high temperatures. The molded article may be a single-layered or multi-layered melt-molded article using the resin composition of the present invention and provided with other layers or other members.

The molded article of the present invention can be used as daily necessities, packaging materials, machine parts, etc. that require the above properties. Examples of applications in which the features of the molded product are particularly effective include food and drink packaging materials, container packing materials, medical infusion bag materials, high-pressure tank materials, gasoline tank materials, fuel containers, beverage containers, Tube material for tires, cushion material for shoes, inner bag material for bag-in-box, tank material for storing organic liquid, pipe material for transporting organic liquid, hot water pipe material for heating (hot water pipe material for floor heating, etc.), resin wallpaper etc. Among them, containers such as fuel containers and beverage containers are preferred, fuel containers such as gasoline tanks, kerosene tanks and hydrogen tanks are more preferred, and hydrogen tanks are even more preferred. The fuel container may be provided with a filter, a fuel gauge, a baffle plate, etc., in addition to the container body formed from the resin composition of the present invention.

The molded article of the present invention is preferably a blow-molded container, more preferably a blow-molded fuel container, and even more preferably a blow-molded hydrogen tank. These molded articles may be multi-layered or single-layered, but when they are single-layered as described above, the advantage of using the resin composition of the present invention can be more fully enjoyed.

<Method for manufacturing molded body>
A method for producing a molded article according to one embodiment of the present invention includes a step of blow molding using the resin composition of the present invention, and can suppress drawdown and perform blow molding efficiently.

The method for producing the molded article of the present invention can be carried out by a known blow molding method except for using the resin composition of the present invention. For example, using a known blow molding machine, blow molding is performed at a temperature of 100° C. to 400° C. using a parison having at least one layer of the resin composition of the present invention, and the temperature in the mold is 10° C. to 30° C. C. for 10 seconds to 30 minutes, a hollow container having an average thickness of all layers of 300 μm to 10,000 μm can be molded. The parison may be a single-layer parison made only of the resin composition of the present invention.

The blow molding in the production method of the present invention may be single layer or multilayer blow molding, but in the case of multilayer blow molding, the advantages of using the resin composition of the present invention are more fully received. . Moreover, the manufacturing method may further include a step of providing another layer or another member on the blow-molded article obtained by blow molding.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to the examples shown below. In addition, the evaluation method followed the following method, respectively.

<Evaluation method>
(1) Melt tension For the resin composition pellets obtained in Examples or Comparative Examples, the melt tension was measured using "Capilograph 1D" manufactured by Toyo Seiki Seisakusho, which is a testing device conforming to JIS K7199: 1999. . The measurement conditions were a measurement temperature of 220° C., a capillary diameter of 1 mm, a length of 10 mm, a piston speed of 15 mm/min, and a take-up speed of 7.5 m/min.

(2) Breaking elongation The breaking elongation of the resin composition pellets obtained in Examples or Comparative Examples was measured according to JIS K7160. Specifically, using a 1A dumbbell obtained by the following “Method for manufacturing a dumbbell”, the tensile strength was measured at −40° C./0% RH and at a tensile speed of 50 mm/min.
(How to make a dumbbell)
Equipment: Injection molding machine (Nissei Plastic Industry's "FS-80S 12AS")
Temperature conditions: Hopper/C1/C2/C3/C4/Nozzle1/Nozzle2=45/200/220/220/200/210°C
Mold temperature: 50°C
Cooling time: 40 seconds

(3) Oxygen transmission rate (OTR)
Using the resin composition pellets obtained in Examples or Comparative Examples, a single layer film having a thickness of 20 μm obtained under the conditions described in "Preparation of Single Layer Film" below was prepared at 20° C./65% RH. After conditioning the humidity, the oxygen transmission rate (OTR) was measured under the conditions of 20° C./65% RH using an oxygen transmission rate measurement device (Modern Control "OX-Tran 2/20").
(Preparation of monolayer film)
Using a single-screw extruder (Toyo Seiki Seisakusho "D2020", D (mm) = 20, L / D = 20, compression ratio = 3.0, screw: full flight), a thickness of 20 μm is extruded from the resin composition pellets. A monolayer film was produced. Extrusion conditions are as shown below.
Extrusion temperature: 220°C
Dice width: 30cm
Take-up roll temperature: 80°C
Screw rotation speed: 45 rpm
Take-up roll speed: 3.4 m/min

(4) Blow molding test For the resin composition pellets obtained in Examples or Comparative Examples, a dedicated adapter with a die diameter of 3 cm was installed in Toyo Seiki Seisakusho's "Laboplastomill 4C150", and the following "blow molding conditions" A blow molding test was performed at In this blow molding test, the time (seconds) from the exit of the die to the point of 100 cm was measured.
(Blow molding conditions)
Laboplastomill temperature conditions: C1/C2/C3/Die = 190/210/210/250°C
Rotation speed: 50rpm

<Materials used in Examples and Comparative Examples>
EVOH (A) and thermoplastic resin (B) used in Examples and Comparative Examples are as follows.
・EVOH (A)
A-1: EVAL (registered trademark) L171B (manufactured by Kuraray Co., Ltd., ethylene-vinyl alcohol copolymer, ethylene unit content 27 mol%, melting point 190° C.)
A-2: EVAL (registered trademark) M100B (manufactured by Kuraray Co., Ltd., ethylene-vinyl alcohol copolymer, ethylene unit content 24 mol%, melting point 195° C.)
A-3: EVAL (registered trademark) F171B (manufactured by Kuraray Co., Ltd., ethylene-vinyl alcohol copolymer, ethylene unit content 32 mol%, melting point 183° C.)
A-4: EVAL (registered trademark) E171B (manufactured by Kuraray Co., Ltd., ethylene-vinyl alcohol copolymer, ethylene unit content 44 mol%, melting point 165 ° C.)
・Thermoplastic resin (B)
B-1: TAFMER (trademark) MH7010 (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified ethylenebutene copolymer, acid value 6 mgKOH/g)
B-2: TAFMER (trademark) MH7020 (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified ethylenebutene copolymer, acid value 12 mgKOH/g)
B-3: Tuftec (trademark) M1943 (manufactured by Asahi Kasei Corporation, hydrogenated maleic anhydride-modified styrene-butadiene-styrene triblock copolymer, acid value 15 mgKOH/g)
B-4: TAFMER (trademark) P0610 (manufactured by Mitsui Chemicals, Inc., ethylene-propylene copolymer, acid value 0 mgKOH/g)
B-5: Estane (registered trademark) 58300 (manufactured by Lubrizol, TPU, acid value 0 mgKOH/g)

[Example 1]
Using 60 parts by mass of EVOH (A-1) as EVOH (A) and 40 parts by mass of thermoplastic resin (B-2) as thermoplastic resin (B), after dry blending, twin screw extrusion of Japan Steel Works It was supplied to a machine "TEX30α" (screw diameter 30 mm) and melt extruded. Melt extrusion was performed under conditions of a melt temperature of 220° C. and an extrusion rate of 20 kg/hr. The extruded strand was cooled and solidified in a cooling bath and then cut to obtain resin composition pellets of Example 1. The obtained resin composition pellets were subjected to melt tension measurement, breaking elongation measurement, OTR measurement and blow molding test according to the methods described in (1) to (4) above. Table 1 shows the evaluation results.

[Examples 2 to 6, Comparative Examples 1 to 7]
Resin composition pellets were prepared in the same manner as in Example 1, except that the type and amount of EVOH (A) and the type and amount of thermoplastic resin (B) were changed as shown in Table 1. , conducted an evaluation. Table 1 shows the evaluation results.

[Comparative Example 8]
Resin composition pellets were produced and evaluated in the same manner as in Example 5, except that the extrusion rate was changed from 20 kg/hr to 5 kg/hr. Table 1 shows the evaluation results.

Examples 1-6 have a higher melt tension than Comparative Examples 1-8, and also show high values in the blow molding test. The results of the blow molding test show that the resin compositions of Examples 1 to 6 can suppress drawdown in parison molding by blow molding. In addition, it can be seen that the resin compositions of Examples 1 to 6 have high gas barrier properties and can provide molded articles having sufficient mechanical properties. In addition, when comparing Examples, it can be seen that Example 3 has a lower ethylene unit content than Example 1, so that it has a high melt tension and can further suppress drawdown in blow molding. Moreover, since Example 3 has a smaller ethylene unit content than Example 1, it has high gas barrier properties.

On the other hand, when the thermoplastic resin (B) having a modifying group is not included as in Comparative Example 1, when the thermoplastic resin (B) has a low acid value as in Comparative Example 2, as in Comparative Examples 3 and 4 In addition, when the mass ratio of EVOH (A) and thermoplastic resin (B) is outside the range of 50/50 to 90/10, it has a modifying group capable of reacting with EVOH as in Comparative Examples 5 and 6. In the case of using a thermoplastic resin with no content, and in the case of using EVOH (A) having a high ethylene unit content as in Comparative Example 7, the melt tension becomes a low value. Moreover, when the kneading strength is lowered as in Comparative Example 8, the melt tension is also lowered. Although the cause of this is not clear, it is presumed that the reaction between EVOH (A) and thermoplastic resin (B) is insufficient and the dispersion is insufficient. As in these Comparative Examples 1 to 8, when the melt tension is low, the measured value in the blow molding test is small, indicating that drawdown is likely to occur.

The resin composition of the present invention can be suitably used for fuel containers, particularly hydrogen tanks and the like.

Claims (11)

A single-layer or multi-layer structure having at least one layer made of a resin composition,
The resin composition contains an ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) having a modifying group capable of reacting with the ethylene-vinyl alcohol copolymer (A), and ethylene-vinyl alcohol The mass ratio (A/B) between the copolymer (A) and the thermoplastic resin (B) is 50/50 to 90/10, and the ethylene unit content of the ethylene-vinyl alcohol copolymer (A) is 10. ~ 35 mol%, the melt tension of the resin composition at 220 ° C. is 40 to 130 mN ,
A layer structure in which the thermoplastic resin (B) is an α-olefin polymer, a polystyrene thermoplastic elastomer or a polyolefin thermoplastic elastomer and is a resin modified with an unsaturated carboxylic acid or a derivative thereof ( However, this excludes the case where one surface of the layer made of the resin composition is directly adjacent to a layer made of polyolefin having no polar functional group). 2. The layer structure according to claim 1 , wherein the thermoplastic resin (B) has an acid value of 1 to 20 mgKOH/g. 3. The layered structure according to claim 1, wherein the ethylene-vinyl alcohol copolymer (A) and the thermoplastic resin (B) have a mass ratio (A/B) of 50/50 to 85/15. The layer structure according to any one of claims 1 to 3 , wherein the total content of the ethylene-vinyl alcohol copolymer (A) and the thermoplastic resin (B) in the resin composition is 99% by mass or more. . If it is multilayer,
At least one adhesive layer, and at least one layer formed from a thermoplastic resin other than the ethylene-vinyl alcohol copolymer (A) and the thermoplastic resin (B),
The layer structure according to any one of claims 1 to 4 , wherein the layer made of the resin composition and the layer made of the other thermoplastic resin are all laminated via the adhesive layer. . In the case of multiple layers, a layer made of the above resin composition, an adhesive layer, and a layer made of a thermoplastic resin other than the ethylene-vinyl alcohol copolymer (A) and the thermoplastic resin (B), or
The first thermoplastic resin layer formed from the other thermoplastic resin, the first adhesive layer, the layer made of the resin composition, the second adhesive layer, and the second thermoplastic resin formed from the other thermoplastic resin 5. The layer structure according to any one of claims 1 to 4 , comprising a layer structure of two thermoplastic resin layers. The layer structure according to any one of claims 1 to 6 , which is for blow molding. A molded article having at least one layer made of a resin composition,
The resin composition contains an ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) having a modifying group capable of reacting with the ethylene-vinyl alcohol copolymer (A), and ethylene-vinyl alcohol The mass ratio (A/B) between the copolymer (A) and the thermoplastic resin (B) is 50/50 to 90/10, and the ethylene unit content of the ethylene-vinyl alcohol copolymer (A) is 10. ~ 35 mol%, the melt tension of the resin composition at 220 ° C. is 40 to 130 mN ,
The thermoplastic resin (B) is an α-olefin polymer, polystyrene thermoplastic elastomer or polyolefin thermoplastic elastomer and is a resin modified with an unsaturated carboxylic acid or a derivative thereof , molded article However, this excludes the case where one surface of the layer made of the resin composition is directly adjacent to a layer made of polyolefin having no polar functional group). 9. The molded article according to claim 8 , which is a blow-molded container. 9. The shaped article according to claim 8 , which is a fuel container. A method for producing a molded body comprising a step of blow molding using a resin composition,
The resin composition contains an ethylene-vinyl alcohol copolymer (A) and a thermoplastic resin (B) having a modifying group capable of reacting with the ethylene-vinyl alcohol copolymer (A), and ethylene-vinyl alcohol The mass ratio (A/B) between the copolymer (A) and the thermoplastic resin (B) is 50/50 to 90/10, and the ethylene unit content of the ethylene-vinyl alcohol copolymer (A) is 10. ~ 35 mol%, the melt tension of the resin composition at 220 ° C. is 40 to 130 mN ,
The molded article, wherein the thermoplastic resin (B) is an α-olefin polymer, a polystyrene thermoplastic elastomer or a polyolefin thermoplastic elastomer and is a resin modified with an unsaturated carboxylic acid or a derivative thereof . Manufacturing method (Excluding the case where one surface of the layer of the resin composition is directly adjacent to a layer of polyolefin having no polar functional group in the molded article to be manufactured).