Resin composition, method for producing resin composition, molded article, multilayer structure, and packaged article

Abstract

Provided is a resin composition from which a molded product exhibiting excellent mechanical strength is obtained, said resin composition containing: a thermoplastic resin (A) which does not contain a polar group; a thermoplastic resin (B) which contains a polar group; an ethylene-vinyl alcohol copolymer (C) which has an ethylene content of 20 to 60 mol%; an acetic acid and / or a salt thereof (D); an aliphatic carboxylic acid (E) which has 3 or more carbon atoms; and an aliphatic carboxylic acid metal salt (F) which is a metal salt of the aliphatic carboxylic acid (E). The (A) content is 66 to 99 wt% of the total of the resin composition and the (C) content is 0.1 to 25 wt% of the total of the resin composition.

Description

[Technical Field]

[0001] The present invention relates to a resin composition containing a thermoplastic resin not containing a polar group, a thermoplastic resin containing a polar group, and an ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH") having an ethylene content of 20 to 60 mol%, and more specifically to a resin composition having excellent mechanical strength. [Background technology]

[0002] Conventionally, laminates containing a thermoplastic resin layer not containing polar groups, such as polyethylene or polypropylene, and a layer made of EVOH (hereinafter sometimes abbreviated as "EVOH layer"), which has excellent gas barrier properties, have been molded into films, sheets, cups, trays, bottles, etc., and have been applied to various uses by taking advantage of their properties, particularly commercial use as packaging materials for food and medicine. When producing such molded products using laminates containing such a thermoplastic resin layer not containing polar groups and an EVOH layer, scrap is generated, including unwanted parts such as waste and edges, defective products, and waste after using the molded product for various purposes. Such scrap accounts for as much as 30 to 50% (by area) of the original laminate. Therefore, this scrap is sometimes recovered and melt-molded, and the recovered material is reused as at least one layer of the laminate (a so-called regrind layer; in the present invention, this recycled layer is sometimes referred to as a "regrind layer").

[0003] Furthermore, in recent years, activities to reduce waste plastics have become more active, and in some cases, used container waste made from the above-mentioned molded products discharged from ordinary households is collected, melt-molded, and reused as recycled molded products such as films, sheets, cups, trays, bottles, etc. Such recycling technologies are industrially useful in terms of waste reduction and economic efficiency, and have been put to practical use.

[0004] However, because thermoplastic resins that do not contain polar groups have poor compatibility with EVOH, when recovered laminates having a thermoplastic resin layer that does not contain polar groups and an EVOH layer are remelted and reused as regrind layers or recycled molded articles, the thermoplastic resins that do not contain polar groups and the EVOH are likely to have poor compatibility during melting, which can cause, for example, the generation of pitting during the production of molded articles, the formation of fish eyes and holes in the molded articles, and poor appearance such as the formation of wavy patterns on the surface.

[0005] Therefore, in order to improve the compatibility that causes the above-mentioned eye boogers and poor appearance, a technique of blending a saponified ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as "EVA") with a high ethylene content is known (see Patent Documents 1 to 3).

[0006] The saponified EVA having a high ethylene content is specifically characterized by having an ethylene content of 70 mol % or more and having high compatibility with polyolefins. In contrast, the EVOH is also a saponified EVA, but has an ethylene content of 20 to 60 mol % and is characterized by excellent gas barrier properties.

[0007] The present inventors have attempted the methods described in the above Patent Documents 1 to 3, and have found that although these techniques provide relatively good results in addressing the problems associated with poor compatibility between thermoplastic resins that do not contain polar groups and EVOH, they also encounter the problem of discoloration of the resulting regrind layer to yellow or red. To prevent this discoloration, the present inventors have also attempted to reduce the content of saponified EVA with a high ethylene content, but this method reduces the compatibilizing effect and insufficiently alleviates the problems associated with poor compatibility (reduced mechanical strength), so further improvement is needed.

[0008] On the other hand, a resin composition has been proposed in which a resin containing EVA and a saponified EVA with a high ethylene content as a base resin is used as a modifier for improving the poor compatibility of the regrind layer (see Patent Document 4). However, even when this resin composition is used, there is still room for improvement in the problem of reduced mechanical strength.

[0009] Furthermore, in order to improve compatibility, which is the cause of the aforementioned decrease in mechanical strength, a technique of blending a thermoplastic resin containing a polar group, such as maleic anhydride-modified polyethylene or maleic anhydride-modified polypropylene, is known (see Patent Document 5). However, even when this resin composition is used, there is still room for improvement in the problem of the aforementioned decrease in mechanical strength. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 3-215032 [Patent Document 2] Japanese Patent Application Publication No. 3-72542 [Patent Document 3] Japanese Patent Application Publication No. 3-72539 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-234971 [Patent Document 5] International Publication No. 2012 / 060371 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above circumstances and provides a resin composition that enables the obtained molded article to have excellent mechanical strength even when it is reused as a resin composition from waste, unwanted parts such as edges, or defective products generated during the production of laminates containing polar groups, thermoplastic resins containing no polar groups, or EVOH, or from recovered waste after the molded article has been used for various purposes. The present invention also provides a method for producing the resin composition, a molded article, a multilayer structure, and a package. [Means for solving the problem]

[0012] However, the present inventors have conducted extensive research in light of these circumstances and have found that a resin composition having excellent mechanical strength can be obtained by combining a thermoplastic resin (A) containing no polar groups, a thermoplastic resin (B) containing a polar group, EVOH (C), acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (F) which is a metal salt of the aliphatic carboxylic acid (E), and by setting the contents of the thermoplastic resin (A) containing no polar groups and the EVOH (C) within specific ranges.

[0013] Specifically, it is generally known that metal salts of aliphatic carboxylic acids accelerate the thermal decomposition of EVOH and reduce the mechanical strength of resin compositions containing EVOH. Therefore, those skilled in the art would avoid incorporating metal salts of aliphatic carboxylic acids when attempting to improve the mechanical strength of resin compositions containing EVOH. However, the present inventors have found that by combining a thermoplastic resin not containing a polar group, a thermoplastic resin containing a polar group, EVOH, acetic acid and / or its salt, an aliphatic carboxylic acid having 3 or more carbon atoms, and a metal salt of the aliphatic carboxylic acid in a specific relationship, the mechanical strength of the composition is improved, contrary to conventional expectations.

[0014] Thus, a first aspect of the present invention is a resin composition containing a thermoplastic resin (A) containing no polar groups, a thermoplastic resin (B) containing a polar group, EVOH (C), acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (F) which is a metal salt of the aliphatic carboxylic acid (E), wherein the content of the thermoplastic resin (A) containing no polar groups is 66 to 99 wt % of the total resin composition, and the content of the EVOH (C) is 0.1 to 25 wt % of the total resin composition.

[0015] The second aspect is a method for producing a resin composition by melt-kneading and pelletizing the resin composition of the first aspect above, the third aspect is a molded product using the resin composition of the first aspect above, the fourth aspect is a multilayer structure having at least one layer made of the resin composition of the first aspect above, and the fifth aspect is a package made of the multilayer structure of the fourth aspect above. [Effects of the Invention]

[0016] The resin composition of the present invention contains a thermoplastic resin (A) containing no polar groups, a thermoplastic resin (B) containing a polar group, EVOH (C), acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (F) which is a metal salt of the aliphatic carboxylic acid (E). Since the content of the thermoplastic resin (A) containing no polar groups is 66 to 99% by weight and the content of the EVOH (C) is 0.1 to 25% by weight, based on the total weight of the resin composition, the resin composition has excellent mechanical strength.

[0017] Furthermore, if the thermoplastic resin (A) not containing a polar group is at least one selected from polyolefin-based resins and polystyrene-based resins, the recyclability and economy are further improved.

[0018] Furthermore, if the thermoplastic resin (A) not containing a polar group is at least one selected from polyethylene, polypropylene and polystyrene, the recyclability and economy are further improved.

[0019] Furthermore, when the content of the thermoplastic resin (B) containing a polar group is 0.1 to 50% by weight based on the total weight of the resin composition, the mechanical strength, recyclability and economy are improved.

[0020] Furthermore, when the thermoplastic resin (B) containing a polar group is a modified thermoplastic resin containing a carboxy group or an acid anhydride group, the mechanical strength, recyclability and economy are further improved.

[0021] Furthermore, when the thermoplastic resin (B) containing the polar group is at least one selected from modified polyolefin resins and polyvinyl acetate resins containing a carboxy group or an acid anhydride group, the resulting resins are particularly excellent in mechanical strength, recyclability, and economy.

[0022] Furthermore, when the content of the acetic acid and / or its salt (D) in terms of acetate ions is 0.01 to 1000 ppm relative to the total of the resin composition, the mechanical strength is even more excellent.

[0023] Furthermore, when the content of the aliphatic carboxylic acid (E) having 3 or more carbon atoms in terms of carboxylate ions is 0.0001 to 150 ppm relative to the total of the resin composition, the mechanical strength is even more excellent.

[0024] Furthermore, when the content of the aliphatic carboxylic acid metal salt (F) calculated as metal ions is 0.01 to 90 ppm relative to the total amount of the resin composition, the mechanical strength is even more excellent.

[0025] Furthermore, the above-mentioned method for producing a resin composition is a production method that provides superior mechanical strength.

[0026] Furthermore, the molded article obtained using the resin composition has excellent mechanical strength.

[0027] Furthermore, a multilayer structure having at least one layer made of the resin composition has excellent mechanical strength.

[0028] Furthermore, since the packaging body of the present invention is made of the above-mentioned multilayer structure, the resulting packaging body also has excellent mechanical strength. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be described in detail below, but these are examples of preferred embodiments. In the present invention, "y and / or z (y and z are optional constituents or components)" means three combinations: y only, z only, and y and z.

[0030] The resin composition of the present invention contains a thermoplastic resin (A) containing no polar groups (hereinafter sometimes simply referred to as "thermoplastic resin (A)"), a thermoplastic resin (B) containing a polar group (hereinafter sometimes simply referred to as "thermoplastic resin (B)"), EVOH (C), acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (F) which is a metal salt of the aliphatic carboxylic acid (E). Each of the constituent components will be described below.

[0031] <Thermoplastic resin (A)> The thermoplastic resin (A) containing no polar groups used in the present invention is, for example, a thermoplastic resin containing no polar groups such as hydroxyl groups, carboxyl groups, amino groups, or amide groups, and the type thereof is not particularly limited. Examples of the thermoplastic resin (A) include polyolefin resins and polystyrene resins. Fat, etc. These may be used alone or in combination of two kinds.

[0032] Examples of the polyolefin resin include polyethylene (PE), such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE); polypropylene (PP); ethylene-propylene (block or random) copolymers; propylene-α-olefin (α-olefins having 4 to 20 carbon atoms) copolymers; ethylene-α-olefin (α-olefins having 4 to 20 carbon atoms) copolymers; olefin homopolymers or copolymers, such as polybutene, polypentene, and polymethylpentene; polycyclic olefins; and blends thereof. These may be used alone or in combination of two or more. Among these, polyethylene (PE), ethylene-propylene (block or random) copolymers, polypropylene (PP), and blends thereof are preferred in terms of economy and mechanical properties. Furthermore, polyethylene (PE), polypropylene (PP), and ethylene-propylene (block or random) copolymers are particularly preferred because they provide particularly excellent effects of the present invention.

[0033] Furthermore, the ethylene and α-olefins in the polyolefin resins may be plant-derived ethylene and α-olefins derived from bioethanol, or non-plant-derived, i.e., petroleum-derived ethylene and α-olefins, or two of these may be used in combination. Because a wide variety of petroleum-derived α-olefins are available, the physical properties of the polyolefin resins can be easily adjusted by using these α-olefins in production. By using plant-derived ethylene and α-olefins, the biomass content of the final product can be further increased, reducing the burden on the environment.

[0034] The plant-derived ethylene and α-olefins can be produced according to conventional methods, such as by fermenting sugar solutions or starch obtained from plants such as sugarcane, corn, and sweet potato using microorganisms such as yeast to produce bioethanol, which is then heated in the presence of a catalyst to obtain plant-derived ethylene and α-olefins (1-butene, 1-hexene, etc.) through intramolecular dehydration or the like. Furthermore, the plant-derived ethylene and α-olefins thus obtained can be used to produce plant-derived polyethylene resins in the same manner as in the production of petroleum-derived polyethylene resins.

[0035] The plant-derived ethylene, α-olefin, and methods for producing the plant-derived polyethylene resin are described in detail, for example, in JP-A No. 2011-506628, etc. Examples of plant-derived polyethylene resins that can be suitably used in the present invention include Green PE manufactured by Braskem SA.

[0036] The polyolefin resin is preferably one produced using a Ziegler catalyst and contains 0.01 to 500 ppm, preferably 0.1 to 400 ppm, more preferably 1 to 300 ppm, and particularly preferably 5 to 150 ppm of chlorine derived from the catalyst. By using such a polyolefin resin, the effects of the present invention can be more significantly achieved.

[0037] Examples of the polystyrene resin include homopolymers of styrene monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene, or copolymers thereof; copolymers of vinyl monomers polymerizable with styrene monomers, mainly composed of styrene monomers; copolymers of styrene monomers and rubber components such as butadiene; and so-called high-impact polystyrenes, which are mixtures or polymers of homopolymers of styrene monomers, copolymers thereof, or copolymers of styrene monomers and vinyl monomers with diene rubber polymers. These polystyrene resins may be used alone or in combination of two or more.

[0038] Examples of vinyl monomers polymerizable with the styrene-based monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and cetyl (meth)acrylate, and bifunctional monomers such as (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate. These vinyl monomers may be used alone or in combination of two or more.

[0039] Examples of the diene rubber polymer include polybutadiene, styrene-butadiene copolymer, and ethylene-propylene-non-conjugated diene three-dimensional copolymer.

[0040] The polystyrene resin is preferably a polystyrene resin containing 50% by mass or more of styrene, and among these, polystyrene is more preferred from the viewpoint of economy.

[0041] Among the above thermoplastic resins (A), at least one selected from polyolefin resins and polystyrene resins is preferred, from the viewpoint of excellent recyclability and economic efficiency, and at least one selected from polyethylene, polypropylene, and polystyrene is more preferred, with polypropylene being particularly preferred.

[0042] The melt flow rate (MFR) (230°C, load 2160g) of the thermoplastic resin (A) is usually 0.1 to 100g / 10 minutes, preferably 0.5 to 50g / 10 minutes.

[0043] The content of the thermoplastic resin (A) is 66 to 99% by weight, preferably 70 to 98% by weight, and more preferably 80 to 95% by weight, based on the total weight of the resin composition. In the present invention, since the content of the thermoplastic resin (A) is within the above range, the mechanical strength is excellent. If the content of the thermoplastic resin (A) is too low, the mechanical strength will be insufficient, and if the content is too high, the gas barrier properties and heat resistance rigidity of the laminate structure will be insufficient.

[0044] <Thermoplastic resin (B)> The polar group-containing thermoplastic resin (B) used in the present invention is not particularly limited as long as it is a resin other than the EVOH (C) described below. Examples include modified thermoplastic resins containing carboxyl or acid anhydride groups (e.g., modified polyolefin resins, modified polystyrene resins, etc.) obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to the thermoplastic resin (A) by addition reaction, graft reaction, etc., as well as polyvinyl acetate resins, polyvinyl alcohol resins, ionomer resins modified with metal ions, polyamide resins, polyester resins, polyurethane resins, polycarbonate resins, and acrylic resins. These may be used alone or in combination of two or more. Among these, modified thermoplastic resins containing carboxyl or acid anhydride groups are preferred from the viewpoints of excellent mechanical strength, recyclability, and economic efficiency. Furthermore, from the viewpoints of excellent mechanical strength, recyclability, and economic efficiency, at least one selected from polyolefin resins containing carboxyl or acid anhydride groups and polyvinyl acetate resins is preferred. A combination of a polyolefin resin containing carboxyl or acid anhydride groups and a polyvinyl acetate resin is more preferred.

[0045] The thermoplastic resin (A) used in the modified thermoplastic resin containing a carboxy group or an acid anhydride group is preferably a polyolefin resin or a polystyrene resin described above for the thermoplastic resin (A).

[0046] Examples of the unsaturated carboxylic acid used in the modified thermoplastic resin containing a carboxy group or an acid anhydride group include unsaturated dicarboxylic acids and unsaturated monocarboxylic acids. Examples of the unsaturated dicarboxylic acids include maleic acid, fumaric acid, chloromaleic acid, himic acid, citraconic acid, and itaconic acid. Examples of the unsaturated monocarboxylic acids include acrylic acid, butanoic acid, crotonic acid, vinylacetic acid, methacrylic acid, pentenoic acid, dodecenoic acid, linoleic acid, angelic acid, and cinnamic acid. Examples of the unsaturated carboxylic acid anhydride include the acid anhydrides of the unsaturated dicarboxylic acids or unsaturated monocarboxylic acids. Specific examples include maleic anhydride, himic anhydride, itaconic anhydride, citraconic anhydride, and acrylic anhydride. Two or more of the unsaturated carboxylic acids or unsaturated carboxylic anhydrides may be used in combination. Among these, maleic anhydride is particularly suitable for achieving the effects of the present invention more effectively and from the viewpoints of recyclability and economy.

[0047] The acid value of such modified thermoplastic resins is usually 0.01 to 120 mgKOH / g, preferably 0.5 to 10 mgKOH / g, more preferably 0.5 to 7 mgKOH / g, even more preferably 0.5 to 5 mgKOH / g, and particularly preferably 0.5 to 3 mgKOH / g. If the acid value of the modified thermoplastic resin is too low, the dispersibility of EVOH (C) in the resin composition tends to decrease, resulting in a decrease in the mechanical strength of the resulting molded article. If the acid value of the modified thermoplastic resin is too high, the fluidity of the resin composition tends to decrease, resulting in a non-uniform layer thickness of the resulting molded article. When the modified thermoplastic resin is a mixture of multiple resins, the acid value of the acid-modified thermoplastic resin is the weighted average of the acid values ​​of the individual resins, calculated based on the mixing mass ratio.

[0048] The polyvinyl acetate resin may have a vinyl acetate content of 0.01 to 60% by weight, measured according to JIS K6924-1, relative to the total weight of the monomer components. In order to more easily obtain the effects of the present invention, the vinyl acetate content is preferably 0.02 to 50% by weight, and particularly preferably 0.03 to 30% by weight.

[0049] Furthermore, polyvinyl acetate resins may contain, as monomer components other than vinyl acetate, monomer components copolymerizable with vinyl acetate, such as olefin monomers such as ethylene and propylene; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid; carboxylic acid anhydride group-containing monomers such as maleic anhydride; (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters having an alkyl group containing 1 to 18 carbon atoms; hydroxyl group-containing copolymerizable monomers such as (meth)acrylate hydroxyethyl and (meth)acrylate hydroxypropyl; epoxy group-containing copolymerizable monomers such as (meth)acrylate glycidyl; amino group-containing copolymerizable monomers such as N,N-dimethylaminoethyl (meth)acrylic acid alkyl esters; amide group-containing copolymerizable monomers such as (meth)acrylamide; cyano group-containing copolymerizable monomers such as (meth)acrylonitrile; styrene-based monomers such as styrene; and dienes such as butadiene and isoprene. These may be used alone or in combination of two or more. Among these, ethylene-vinyl acetate copolymer is particularly suitable from the viewpoint that the effects of the invention can be more effectively obtained.

[0050] Furthermore, the polyvinyl acetate resin may be saponified. That is, the polyvinyl acetate resin may have a vinyl alcohol unit as a monomer unit. The saponification degree of the polyvinyl acetate resin is usually 20 mol% or more, preferably 40 to 99.5 mol%, and particularly preferably 70 to 99 mol%, from the viewpoint of more effectively achieving the effects of the invention. However, when the saponified polyvinyl acetate resin is contained in the EVOH (C) described below, it is not included in the thermoplastic resin (B).

[0051] The melt flow rate (MFR) (190°C, load 2160 g) of the polyvinyl acetate resin is usually 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, and particularly preferably 1 to 30 g / 10 min, from the viewpoint of more effectively achieving the effects of the present invention.

[0052] The polyvinyl acetate resin may be a modified product containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride by an addition reaction, a graft reaction, etc., within the scope of the present invention. The amount of such modification is preferably, for example, 10 mol % or less.

[0053] Examples of the unsaturated carboxylic acid or anhydride thereof include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, and crotonic acid, and ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, monoethyl maleate, and maleic anhydride, as well as anhydrides and half esters thereof. Among these, maleic anhydride is preferably used from the viewpoint that the effects of the present invention can be more effectively obtained.

[0054] The polyvinyl acetate resins can be used alone or in combination of two or more types differing in vinyl acetate content, degree of saponification, molecular weight, MFR, density, modifying group, modification amount, etc.

[0055] The polyvinyl alcohol resin (hereinafter, sometimes referred to as "PVOH") is a resin that is usually produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester compound, and the production method thereof is not particularly limited, and it can be produced by a known method.

[0056] Examples of the vinyl ester compounds include vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl laurate, vinyl versatate, vinyl palmitate, vinyl stearate, etc. These may be used alone or in combination of two or more, but vinyl acetate is preferred for practical use.

[0057] The PVOH may be a copolymer of the vinyl ester compound and a copolymerizable monomer, and the content of the vinyl ester compound copolymerizable monomer in the PVOH is preferably less than 20 mol %, more preferably 10 mol % or less, and particularly preferably 7 mol % or less.

[0058] Examples of monomers copolymerizable with the vinyl ester compounds include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, or their salts or mono- or di-alkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, or their salts; alkyl vinyl ethers; polyoxyalkylene (meth)allyl ethers such as polyoxyethylene (meth)allyl ether and polyoxypropylene (meth)allyl ether; polyoxyethylene (meth)acrylate; polyoxypropylene (meth)allyl ether; Examples thereof include polyoxyalkylene (meth)acrylates such as acrylate, polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (meth)acrylamide, polyoxyethylene [1-(meth)acrylamide-1,1-dimethylpropyl] ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, diacrylacetamide, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, etc. These may be used alone or in combination of two or more.

[0059] PVOH can be obtained by saponifying a vinyl ester polymer obtained by polymerizing the vinyl ester compound, etc. The saponification of the vinyl ester polymer is carried out by dissolving the vinyl ester polymer in alcohol (methanol, ethanol, butanol, etc.) in the presence of an alkali catalyst (an alkali metal hydroxide or alcoholate such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, or potassium methylate). The average degree of saponification of PVOH is usually preferably 70 to 99.9 mol %, more preferably 75 to 99 mol %. The PVOH thus obtained may be used as a mixture of two or more types of PVOH having different degrees of saponification, if necessary.

[0060] The metal ion-modified ionomer resin is a known thermoplastic resin having ionic groups on side chains of a hydrophobic polymer main chain. Examples of such ionomer resins include sulfonic acid ionomers in which some or all of the sulfonic acid groups in a sulfonic acid group-containing polymer are neutralized with metal ions, and carboxylic acid ionomers in which some or all of the carboxyl groups in an ethylene-unsaturated carboxylic acid copolymer are neutralized with metal ions.

[0061] Metal ions that neutralize acid moieties, such as sulfonic acid groups and carboxyl groups, in ionomer resins typically include monovalent metal ions such as lithium, sodium, potassium, rubidium, and cesium; divalent metal ions such as calcium, magnesium, iron, and zinc; and trivalent metal ions such as iron and aluminum. The metal cation content in the ionomer is typically 0.4 to 4 mol, preferably 0.6 to 2 mol, per 1 kg of ionomer. Furthermore, the degree of neutralization is preferably such that 15 to 80%, preferably 20 to 60%, of the acid content in the copolymer component is neutralized with the metal cations. Among these, divalent metal ion neutralization products are preferred in terms of affinity with EVOH (C), and zinc ion neutralization products are particularly preferred.

[0062] Specific examples of the sulfonic acid ionomer include polystyrene sulfonate (PSS) ionomers and ethylene sulfonate ionomers. Specific examples of the carboxylic acid ionomer include carboxylate ionomers such as ethylene-unsaturated carboxylic acid copolymers. Among these, it is preferable to use carboxylic acid ionomers, and it is particularly preferable to use ionomers of ethylene-unsaturated carboxylic acid copolymers, in view of their affinity with EVOH (C).

[0063] Examples of the unsaturated carboxylic acid in the ionomer of the ethylene-unsaturated carboxylic acid copolymer include (meth)acrylic acid, maleic acid, fumaric acid, maleic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, etc., and these can be used alone or in combination. Among these, (meth)acrylic acid is particularly preferred.

[0064] The ionomer of ethylene-unsaturated carboxylic acid copolymer may contain a small amount (e.g., less than 20% by weight) of another monomer that can be a copolymerization component. Examples of the other monomer include vinyl esters such as vinyl acetate, and unsaturated (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, and isooctyl (meth)acrylate.

[0065] That is, the ionomer resin is preferably a divalent metal ion neutralized product of an ethylene-(meth)acrylic acid copolymer, and particularly preferably a zinc ion neutralized product of an ethylene-(meth)acrylic acid copolymer.

[0066] As the polyamide resin, known homopolyamide resins and copolymer polyamide resins can be used. Examples of the homopolyamide resin include polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), and polylauryllactam (nylon 12). Examples of the copolymer polyamide resin include polyethylene diamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactamethylene adipamide (nylon 108), Caprolactam / lauryllactam copolymer (nylon 6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 66), lauryllactam / hexamethylenediammonium adipate copolymer (nylon 12 / 66), ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon 26 / 66) Examples of suitable polyamides include aliphatic polyamides such as caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 66 / 610) and ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 66 / 610); aromatic polyamides such as polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymetaxylylene adipamide, hexamethylene isophthalamide / terephthalamide copolymer, poly-p-phenylene terephthalamide, and poly-p-phenylene-3,4'-diphenyl ether terephthalamide; amorphous polyamides; and polyamide resins modified with aromatic amines such as methylenebenzylamine and metaxylylenediamine, as well as metaxylylenediammonium adipate. Furthermore, the polyamide resin may be a terminal-modified polyamide resin obtained by modifying the terminals of the homopolyamide resin or copolymer polyamide resin. These may be used alone or in combination of two or more. Of these, terminal-modified polyamide resins are preferred.

[0067] The polyester resin may be a polymer or copolymer obtained by a condensation reaction of a dicarboxylic acid and a diol, or an ester derivative thereof, as the main components.

[0068] The dicarboxylic acid is preferably an aromatic dicarboxylic acid, such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-biphenyletherdicarboxylic acid, 4,4'-biphenylmethanedicarboxylic acid, 4,4'-biphenylsulfonedicarboxylic acid, 4,4'-biphenylisopropylidenedicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 2,5-anthracenedicarboxylic acid, 2,6-anthracenedicarboxylic acid, 4,4'-p-terphenylenedicarboxylic acid, 2,5-pyridinedicarboxylic acid, etc. Two or more of these dicarboxylic acids may be used in combination.

[0069] In addition, a small amount of aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid may be used in combination with the aromatic dicarboxylic acids.

[0070] Examples of diols include aliphatic diols such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 2-methyl-1,3-propanediol, diethylene glycol, and triethylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol; and mixtures thereof.

[0071] Specific examples of polyester resins include polyethylene terephthalate (hereinafter referred to as "PET"), polypropylene terephthalate, polybutylene terephthalate (hereinafter referred to as "PBT"), polyhexylene terephthalate, polyethylene naphthalate (hereinafter referred to as "PEN"), polybutylene naphthalate (hereinafter referred to as "PBN"), polyethylene-1,2-bis(phenoxy)ethane-4,4'-dicarboxylate, and the like, as well as copolymer polyesters such as polyethylene isophthalate / terephthalate and polybutylene terephthalate / isophthalate. Of these, PET, PBT, PBN, and PEN, which have a good balance of mechanical properties, etc., are preferably used.

[0072] From the viewpoint of excellent compatibility with the thermoplastic resin (A), the thermoplastic resin (B) used in the present invention is preferably an acid-modified thermoplastic resin of the same type as the thermoplastic resin (A). For example, when the thermoplastic resin (A) is polypropylene, the thermoplastic resin (B) is preferably acid-modified polypropylene, and when the thermoplastic resin (A) is polyethylene, the thermoplastic resin (B) is preferably acid-modified polyethylene.

[0073] Although the reason why the use of the thermoplastic resin (B) provides such excellent effects is not clear, it is presumed that the use of the thermoplastic resin (B) reduces the dispersed size of the EVOH (C) present in the resin composition, making it easier for the resin composition to absorb energy when subjected to external deformation, resulting in improved mechanical strength.

[0074] The melt flow rate (MFR) (190°C, 2160 g load) of the thermoplastic resin (B) is usually 0.01 to 1000 g / 10 min, preferably 0.05 to 800 g / 10 min, particularly preferably 0.1 to 200 g / 10 min, and especially preferably 0.5 to 50 g / 10 min. When the MFR of the thermoplastic resin (B) is within this range, a good balance of the viscosities of the thermoplastic resin (B), the thermoplastic resin (A), and the EVOH (C) is achieved. As a result, the dispersibility of the EVOH (C) is further improved, which tends to further improve the mechanical strength of the molded article.

[0075] From the viewpoints of mechanical strength, recyclability, and economy, the content of the thermoplastic resin (B) is preferably 0.1 to 50 wt %, more preferably 0.3 to 25 wt %, even more preferably 0.5 to 15 wt %, and particularly preferably 1.0 to 10 wt %, of the total resin composition. If the content of the thermoplastic resin (B) is too low, the dispersibility of the EVOH (C) tends to decrease, and the mechanical strength of the molded article tends to be insufficient. If the content is too high, the affinity with the EVOH (C) becomes too high, and highly polymerized products tend to be generated, resulting in insufficient moldability as a resin composition and insufficient mechanical strength of the molded article.

[0076] <EVOH(C)> The EVOH (C) used in the present invention is typically a resin obtained by saponifying an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene with a vinyl ester monomer, and is a water-insoluble thermoplastic resin known as an ethylene-vinyl alcohol copolymer or a saponified ethylene-vinyl ester copolymer. Any known polymerization method, such as solution polymerization, suspension polymerization, or emulsion polymerization, can be used, but solution polymerization using methanol as a solvent is generally used. The resulting ethylene-vinyl ester copolymer can also be saponified by a known method.

[0077] That is, the EVOH (C) used in the present invention is mainly composed of ethylene structural units and vinyl alcohol structural units, and also contains a small amount of vinyl ester structural units that remain unsaponified.

[0078] Vinyl acetate is typically used as the vinyl ester monomer because of its ease of commercial availability and the efficiency of treating impurities during production. Other vinyl ester monomers include, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Of these, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are preferred. These are typically used alone, but multiple types may be used simultaneously as needed.

[0079] Furthermore, the EVOH (C) may further contain structural units derived from the comonomers shown below in addition to the ethylene structural units and vinyl alcohol structural units (including unsaponified vinyl ester structural units). Examples of the comonomer include α-olefins such as propylene, isobutene, α-octene, α-dodecene, and α-octadecene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, and 3-butene-1,2-diol, and hydroxyl group-containing α-olefin derivatives such as esters and acylation products thereof; hydroxymethylvinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyronyloxy-2-methylenepropane; unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, nitriles, amides, or anhydrides; unsaturated sulfonic acids or salts thereof; vinylsilane compounds; vinyl chloride; and styrene.

[0080] Furthermore, as the EVOH (C), EVOH that has been "post-modified" by urethanization, acetalization, cyanoethylation, oxyalkylenation, or the like can also be used.

[0081] Among the modified EVOHs described above, EVOHs in which primary hydroxyl groups have been introduced into the side chains by copolymerization are preferred because they have good secondary formability in stretching treatments and vacuum / pressure molding, and EVOHs having a 1,2-diol structure in the side chains are particularly preferred.

[0082] The content of ethylene structural units in the EVOH (C) is 20 to 60 mol%, preferably 25 to 50 mol%, and particularly preferably 25 to 35 mol%, as measured in accordance with ISO 14663. If the content is too low, the gas barrier properties and melt moldability at high humidity will decrease, and conversely, if the content is too high, the gas barrier properties will decrease.

[0083] The saponification degree of the EVOH (C) is measured according to JIS K6726 (wherein the EVOH is a solution uniformly dissolved in a water / methanol solvent) and is usually 90 to 100 mol%, preferably 95 to 100 mol%, and particularly preferably 99 to 100 mol%. If the saponification degree is too low, the gas barrier properties, thermal stability, moisture resistance, etc. tend to decrease.

[0084] The melt flow rate (MFR) of the EVOH (C) (210°C, load 2160 g) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and particularly preferably 3 to 35 g / 10 min. If the MFR is too high, film formability tends to decrease. If the MFR is too low, melt extrusion tends to become difficult.

[0085] Furthermore, the EVOH (C) used in the present invention may be a mixture with other different EVOHs. Examples of such other EVOHs include those having a different ethylene content, a different degree of saponification, a different melt flow rate (MFR), a different other copolymerization component, and a different degree of modification (for example, those having a different content of structural units containing a primary hydroxyl group in the side chain).

[0086] The content of the EVOH (C) is 0.1 to 25% by weight, preferably 0.3 to 20% by weight, and more preferably 0.5 to 15% by weight, based on the total weight of the resin composition, in order to achieve excellent mechanical strength. If the content of EVOH (C) is too low, the gas barrier properties of the molded article will be insufficient, and if the content is too high, the mechanical strength of the molded article will be insufficient.

[0087] <Acetic acid and / or its salt (D)> The resin composition of the present invention contains acetic acid and / or a salt thereof (D), and specific examples of the acetic acid and / or a salt thereof (D) include acetic acid, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, manganese acetate, copper acetate, cobalt acetate, zinc acetate, etc. These can be used alone or in combination of two or more. Among these, preferred are acetic acid, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate, particularly preferred are acetic acid, sodium acetate, and potassium acetate, and even more preferred are acetic acid and sodium acetate.

[0088] The content of the acetic acid and / or its salt (D) in terms of acetate ions is preferably 0.01 to 1000 ppm, more preferably 0.1 to 800 ppm, particularly preferably 5 to 600 ppm, and especially preferably 10 to 400 ppm, relative to the total resin composition, in terms of excellent mechanical strength. If the content is too low, the mechanical strength tends to decrease due to the thermal decomposition products of the aliphatic carboxylic acid metal salt (F) described below, and if the content is too high, the effects of the present invention tend not to be fully achieved.

[0089] The content of the acetic acid and / or its salt (D) calculated as acetate ions is not particularly limited and can be measured by a known analytical method, such as liquid chromatography mass spectrometry (LC / MS) or gas chromatography mass spectrometry (GC / MS).

[0090] In the resin composition of the present invention, the ratio of the metal ion-equivalent content of the aliphatic carboxylic acid metal salt (F) described below to the acetate ion-equivalent content of the acetic acid and / or its salt (D) ((F) metal ion-equivalent content / (D) acetate ion-equivalent content) is typically 0.001≦((F) / (D))≦1.3 by weight, preferably 0.005≦((F) / (D))≦1.1, particularly preferably 0.005≦((F) / (D))≦1.0, and especially preferably 0.01≦((F) / (D))≦0.8. When this value is within the above range, the effects of the present invention tend to be more pronounced; when it is below the above range, the effects of the present invention tend not to be sufficiently achieved; when it is above the above range, the adhesive strength tends to be insufficient.

[0091] The reason why such excellent effects are obtained when the content ratio ((F) / (D)) of the acetic acid and / or its salt (D) to the metal aliphatic carboxylic acid (F), which will be described later, satisfies the above range is not clear. However, it is presumed that a specific amount of acetic acid and / or its salt (D) has the effect of capturing thermal decomposition products of the metal aliphatic carboxylic acid (F) and suppressing a decrease in adhesive strength, while an excessive content of acetic acid and / or its salt (D) significantly reduces the thermal stability of the EVOH (C), preventing the effects of the present invention from being fully achieved.

[0092] <Aliphatic carboxylic acids (E) having 3 or more carbon atoms> The resin composition of the present invention contains an aliphatic carboxylic acid other than acetic acid, i.e., an aliphatic carboxylic acid (E) having 3 or more carbon atoms (hereinafter, may be referred to as "aliphatic carboxylic acid (E)"), and the number of carbon atoms in the aliphatic carboxylic acid (E) is usually 3 to 30, preferably 4 to 20, and particularly preferably 5 to 14. It is preferable from the viewpoint of economy that the number of carbon atoms in the aliphatic carboxylic acid (E) is within the above range.

[0093] Examples of the aliphatic carboxylic acid (E) include an aliphatic monocarboxylic acid having one carboxy group, an aliphatic dicarboxylic acid having two carboxy groups, and an aliphatic tricarboxylic acid having three carboxy groups. Examples of the aliphatic monocarboxylic acids include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, 12-hydroxystearic acid, arachidic acid, heneicosylic acid, behenic acid, lignoceric acid, montanic acid, melissic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, gluconic acid, Examples include saturated aliphatic monocarboxylic acids such as mevalonic acid and pantoic acid, and unsaturated aliphatic monocarboxylic acids such as linoleic acid, linolenic acid, pinolenic acid, eleostearic acid, isostearic acid, isononanoic acid, 2-ethylhexanoic acid, 2-heptylundecanoic acid, 2-octyldodecanoic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, eicosenoic acid, erucic acid, nervonic acid, and ricinoleic acid. Examples of the aliphatic dicarboxylic acids include saturated aliphatic dicarboxylic acids such as succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, and unsaturated aliphatic dicarboxylic acids such as eicosadienoic acid and docosadienoic acid. Examples of the aliphatic tricarboxylic acid include saturated aliphatic tricarboxylic acids such as citric acid, isocitric acid, and aconitic acid. These aliphatic carboxylic acids (E) can be used alone or in combination of two or more. Among them, from the viewpoint of thermal stability (preventing an increase in viscosity during melt molding and the occurrence of fish eyes), aliphatic monocarboxylic acids having one carboxy group are preferred, saturated aliphatic monocarboxylic acids are more preferred, and stearic acid, caproic acid, caprylic acid, lauric acid, and behenic acid are particularly preferred.

[0094] The content of the aliphatic carboxylic acid (E) in terms of carboxylate ions is preferably 0.0001 to 150 ppm, more preferably 0.001 to 100 ppm, particularly preferably 0.005 to 75 ppm, and particularly preferably 0.01 to 50 ppm, relative to the total amount of the resin composition, in terms of excellent mechanical strength. If the content is too low, the thermal stability of the metal salt of an aliphatic carboxylic acid (F), which will be described later, will be insufficient, and as a result, the effects of the invention will tend to be insufficient, whereas if the content is too high, the aliphatic carboxylic acid (E) itself will act as a plasticizer, and the effects of the invention will tend to be insufficient. The content of the aliphatic carboxylic acid (E) in terms of carboxylate ions can be determined by the method described later.

[0095] <Metal salts of aliphatic carboxylic acids (F)> The resin composition of the present invention contains an aliphatic carboxylic acid metal salt (F), which is a metal salt of the above aliphatic carboxylic acid (E).

[0096] Examples of the metal species of the aliphatic carboxylic acid metal salt (F) include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, and barium; and transition metals such as chromium, cobalt, nickel, copper, iron, and zinc. Of these, sodium, potassium, calcium, magnesium, iron, and zinc are preferred, as they are likely to provide the effects of the present invention; sodium, calcium, magnesium, and zinc are particularly preferred; and zinc is particularly preferred, as it is likely to provide particularly excellent effects and is inexpensive and easily available.

[0097] Although the reason why the use of the metal salt of aliphatic carboxylic acid (F) provides such excellent effects is not clear, it is presumed that the use of the metal salt of aliphatic carboxylic acid (F) enhances the interaction between the thermoplastic resin (A), the thermoplastic resin (B), and the EVOH (C) in the resin composition, thereby making the molecular orientation and higher-order structures such as the crystalline structure formed when the resin composition is extrusion-molded highly uniform, resulting in improved mechanical strength.

[0098] As the anion species of the metal salt of aliphatic carboxylic acid (F), those exemplified as the aliphatic carboxylic acid (E) can be used. Furthermore, in the present invention, it is important that the anion species of the metal salt of aliphatic carboxylic acid (F) and the anion species of the aliphatic carboxylic acid (E) are the same species. When the anion species of the metal salt of aliphatic carboxylic acid (F) and the anion species of the aliphatic carboxylic acid (E) are the same species, a resin composition excellent in mechanical strength can be obtained. In addition, when the resin composition of the present invention contains a plurality of the aliphatic carboxylic acids (E) or a plurality of the aliphatic carboxylic acid metal salts (F), it is sufficient that the anion species of at least one of the aliphatic carboxylic acids (E) and the aliphatic carboxylic acid metal salts (F) are the same species.

[0099] Although the reason why the aliphatic carboxylic acid (E) and the aliphatic carboxylic acid metal salt (F) have the same anion species as each other is unclear, it is presumed that the combined use of the aliphatic carboxylic acid (E) and the aliphatic carboxylic acid metal salt (F) having the same anion species as the aliphatic carboxylic acid (E) significantly improves the dispersibility of the aliphatic carboxylic acid metal salt (F), thereby achieving a more excellent effect of the present invention. Furthermore, it is presumed that the aliphatic carboxylic acid (E) interacts with the metal species of the aliphatic carboxylic acid metal salt (F) and exists in a metal complex-like state. Since the anion species of the aliphatic carboxylic acid metal salt (F) is the same as that of the aliphatic carboxylic acid (E), it is possible for the aliphatic carboxylic acid (E) to exist in a more energetically stable state, resulting in excellent thermal stability during melt molding and, as a result, in improved mechanical properties of the resin composition.

[0100] The content of the aliphatic carboxylic acid metal salt (F) in terms of metal ions is preferably 0.01 to 90 ppm, more preferably 0.05 to 80 ppm, particularly preferably 0.08 to 60 ppm, and particularly preferably 0.1 to 50 ppm, based on the total amount of the resin composition, in terms of excellent mechanical strength. If the content of the aliphatic carboxylic acid metal salt (F) is too low or too high, the effects of the present invention tend not to be fully achieved.

[0101] The content of the aliphatic carboxylic acid metal salt (F) calculated as a metal ion and the content of the aliphatic carboxylic acid (E) calculated as a carboxylate ion are not particularly limited and can be measured by a known analytical method. For example, they can be determined by the following methods alone or in combination: [Aliphatic carboxylic acid metal salt (F) content converted to metal ion] The dried sample is accurately weighed and placed in a constant-weight platinum evaporating dish. It is then carbonized using an electric heater and heated with a gas burner until no more smoke is emitted. The platinum evaporating dish is then placed in an electric furnace and heated until completely incinerated. After cooling, hydrochloric acid and pure water are added to the ashes, which are then dissolved using an electric heater. The solution is poured into a measuring flask and the volume is adjusted to a constant level with pure water to prepare a sample for atomic absorption spectrometry. The amount of metal in this sample for atomic absorption spectrometry can be quantitatively analyzed using atomic absorption spectrometry to determine the content of aliphatic carboxylic acid metal salt (F) in terms of metal ions. [Aliphatic carboxylic acid (E) content converted into carboxylate ion] The total content (e x ) is then quantified. Then, the content of the aliphatic carboxylic acid metal salt (F) converted into carboxylate ion (e y ) is calculated. The total content of aliphatic carboxylic acid (E) and its metal salt (F) converted to carboxylate ion (e x) and the content of aliphatic carboxylic acid metal salts (F) converted to carboxylate ions (e y ) difference ((e x )―(e y )) to determine the content of aliphatic carboxylic acid (E) converted into carboxylate ion.

[0102] Furthermore, in the resin composition of the present invention, the ratio of the content of the aliphatic carboxylic acid metal salt (F) in terms of metal ions to the content of the aliphatic carboxylic acid (E) in terms of carboxylate ions ((F) content in terms of metal ions / (E) content in terms of carboxylate ions) is preferably, by weight, usually 0.11≦((F) / (E))≦100, more preferably 0.13≦((F) / (E))≦90, particularly preferably 0.15≦((F) / (E))≦80, and especially preferably 0.2≦((F) / (E))≦70. When this value is within the above range, the effects of the present invention tend to be more pronounced, whereas when it is below the above range, the effects of the present invention tend not to be sufficiently obtained, and when it is above the above range, moldability tends to be insufficient.

[0103] The reason why such excellent effects are obtained by setting the content ratio ((F) / (E)) of the aliphatic carboxylic acid (E) to the aliphatic carboxylic acid metal salt (F) within the above range is not clear, but using the aliphatic carboxylic acid (E) and the aliphatic carboxylic acid metal salt (F) having the same anion species as the aliphatic carboxylic acid (E) in a specific ratio has the effect of improving the dispersibility and thermal stability of the aliphatic carboxylic acid metal salt (F). On the other hand, if the content of the aliphatic carboxylic acid (E) is too high, the aliphatic carboxylic acid (E) itself acts as a plasticizer, and it is presumed that the effect of the present invention (mechanical strength improvement effect) cannot be fully obtained.

[0104] [Other thermoplastic resins] The resin composition of the present invention may contain other thermoplastic resins in addition to the thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) as long as the effects of the present invention are not impaired (for example, 30% by weight or less, preferably 10% by weight or less, based on the total weight of the resin composition). By blending other thermoplastic resins, it is possible to further increase strength or impart other functions.

[0105] Examples of the other thermoplastic resins include polyvinyl chloride, polyvinylidene chloride, acrylic resins, polyester elastomers, polyurethane elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These may be used alone or in combination of two or more.

[0106] <Other additives> The resin composition of the present invention may contain additives that are generally blended into resin compositions, such as heat stabilizers, inorganic fillers, antioxidants, antistatic agents, colorants, ultraviolet absorbers, lubricants (for example, saturated aliphatic amides such as stearic acid amide, unsaturated fatty acid amides such as oleic acid amide, bisfatty acid amides such as ethylene bisstearic acid amide), plasticizers (for example, ethylene glycol, glycerin, hexamethylolpropanediol, etc.), within a range that does not impair the effects of the present invention (for example, usually 30% by weight or less of the resin composition, preferably 10% by weight or less). The composition may contain known additives such as polyolefins (aliphatic polyhydric alcohols such as enediol, etc.), light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, crosslinking agents, foaming agents, crystal nucleating agents, antifogging agents, biodegradable additives, silane coupling agents, oxygen absorbers, phosphoric acid and / or its salts, cinnamic acid and / or its salts, conjugated polyene compounds, enediol group-containing substances (e.g., phenols such as propyl gallate, etc.), aldehyde compounds (e.g., unsaturated aldehydes such as crotonaldehyde, etc.), etc. These may be used alone or in combination of two or more.

[0107] Examples of the inorganic filler include hydrotalcite-based compounds, mica, talc, calcium carbonate, titanium oxide, kaolin, clay, glass flakes, glass beads, vermiculite, smectite, etc. These may be used alone or in combination of two or more kinds.

[0108] Examples of the hydrotalcite-based compound include hydrotalcite-based solid solutions represented by the following general formula (1).

[0109] [Chemical Formula 1] [(M1 2+ ) y1 (M2 2+ ) y2 1-x M x 3+ (OH)2A n- x / n ·mH2O ……(1) [In the formula, M1 2+ is at least one metal selected from Mg, Ca, Sr and Ba, M2 2+ is at least one metal selected from Zn, Cd, Pb and Sn, M x 3+ is a trivalent metal, A n- is an n-valent anion, and x, y1, y2, m are positive numbers represented by 0 < x ≤ 0.5, 0.5 < y1 < 1, y1 + y2 = 1, 0 ≤ m < 2, respectively.]

[0110] In the general formula (1), M1 2+ is preferably Mg or Ca, and M2 2+ is preferably Zn or Cd. Further, examples of M x 3+ include, for example, Al, Bi, In, Sb, B, Ga, Ti, etc. These may be used alone or in combination of two or more kinds, and among them, Al is practical. Also, in the general formula (1), examples of A n- include, for example, CO3 2- , OH - , HCO3 - , salicylate ion, citrate ion, tartrate ion, NO3 - , I -,(OOC-COO) 2- ,ClO 4- ,CH3COO - ,(OOCHC=CHCOO) 2- ,〔Fe(CN)6〕 4- These can be used alone or in combination of two or more types, but CO3 2- OH - is useful.

[0111] As a specific example of the hydrotalcite-based solid solution, [Mg 0.75 Zn 0.25 ] 0.67 Al 0.33 (OH)2(CO3) 0.165 ·0.45H2O, [Mg 0.79 Zn 0.21 ] 0.7 Al 0.3 (OH)2(CO3) 0.15 , [Mg 1 / 7 Ca 3 / 7 Zn 3 / 7 ] 0.7 Al 0.3 (OH)2(OOCHC=CHCOO) 0.15 ·0.41H2O, [Mg 6 / 7 CD 1 / 7 ] 0.7 Al 0.3 (OH)2(CH3COO) 0.3 ·0.34H2O, [Mg 5 / 7 Pd 2 / 7 ] 0.7 Al 0.30 (OH)2(CO3) 0.15 ·0.52H2O, [Mg 0.74 Zn 0.26 ] 0.68 Al 0.32 (OH)2(CO3) 0.16 , [Mg 0.56 Zn 0.44 ] 0.68 Al 0.32 (OH)2(CO3) 0.16 0.2H2O, [Mg 0.81 Zn 0.19 ] 0.74 Al 0.26 (OH)2(CO3) 0.13 , [Mg0.75 Zn 0.25 ] 0.8 Al 0.20 (OH)2(CO3) 0.10 ·0.16H2O, [Mg 0.71 Zn 0.29 ] 0.7 Al 0.30 (OH)2(NO3) 0.30 , [Mg 0.71 Zn 0.29 ] 0.7 Al 0.30 (OH)2(OOCHC=CHCOO) 0.15 , [Mg 0.14 Ca 0.57 Zn 0.28 ] 0.7 Al 0.30 (OH) 2.3 0.25H2O, etc., among which [Mg 0.75 Zn 0.25 ] 0.67 Al 0.33 (OH)2(CO3) 0.165 ·0.45H2O, [Mg 0.79 Zn 0.21 ] 0.7 Al 0.3 (OH)2(CO3) 0.15 , [Mg 6 / 7 CD 1 / 7 ] 0.7 Al 0.3 (OH)2(CH3COO) 0.3 ·0.34H2O, [Mg 5 / 7 Pd 2 / 7 ] 0.7 Al 0.30 (OH))2(CO3) 0.15 0.52H2O, etc.

[0112] Other examples include compounds represented by the following general formula (2).

[0113] [Cation 2] M x Al y (OH) 2x+3y-2z (E) z aH2O ……(2) [In the formula, M is Mg, Ca, or Zn, E is CO3 or HPO4, x, y, and z are positive numbers, and a is 0 or a positive number.]

[0114] Specific examples of the compound represented by the general formula (2) include Mg 4.5 Al2(OH) 13 CO3·3.5H2O, Mg5Al2(OH) 14 CO3·4H2O,Mg6Al2(OH) 16 CO3·4H2O, Mg8Al2(OH) 20 CO₃·5H₂O,Mg 10 Al2(OH) 22 (CO3)2·4H2O, Mg6Al2(OH) 16 HPO4·4H2O, Ca6Al2(OH) 16 CO3·4H2O, Zn6Al6(OH) 16 Examples include CO3·4H2O. In addition to the above, compounds with an unclear chemical formula, such as Mg2Al(OH)9·3H2O in which some of the OH has been replaced with CO3 or HPO4, or compounds with the water of crystallization removed (a = 0), can be expected to produce the same effect. Of these, compounds in which M is Mg and E is CO3 are particularly suitable from the perspective of recyclability.

[0115] Regarding the particle size of the hydrotalcite-based compound, for example, the average particle size is usually 10 μm or less, more preferably 5 μm or less, and particularly preferably 1 μm or less. That is, if the average particle size is too large, the effects of the present invention tend not to be fully obtained. The average particle size referred to here is a value measured by the LUZEX method.

[0116] Among the above hydrotalcites, it is particularly preferable to use the hydrotalcite-based solid solution represented by the above general formula (1) because of its high molding stability.

[0117] The average particle size of the inorganic filler other than the hydrotalcite compound is preferably 1 to 20 μm, more preferably 3 to 18 μm, and particularly preferably 5 to 15 μm. If the average particle size is less than 1 μm, gel will form in the molded product due to aggregation of the particles, and the heat-resistant rigidity of the laminate structure will be insufficient. If the average particle size is more than 20 μm, it will be difficult to suppress an increase in resin pressure.

[0118] The content of the inorganic filler is usually preferably 0.001 to 30% by weight, more preferably 0.005 to 20% by weight, and particularly preferably 0.01 to 10% by weight, based on the total weight of the resin composition.

[0119] Examples of the antioxidant include hindered phenol compounds such as dibutylhydroxytoluene, 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis-(6-t-butylphenol), 2,2'-methylene-bis(4-methyl-6-t-butylphenol), tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, N,N'-hexamethylene-bis(3,5-di-t-butyl-4'-hydroxy-hydrocinnamamide), 1, 3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylaniline lino)-1,3,5-triazine, 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl)calcium, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 2,4-bis[(octylthio) Methyl]-o-cresol, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 3,9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)-propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro(5·5)undecane, etc.; phosphite compounds: triaryl phosphites such as triphenyl phosphite, tris(p-nonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, etc. alkylaryl phosphites such as monoalkyldiphenyl phosphites, dialkylmonophenyl phosphites such as phenyldiisooctyl phosphite and phenyldiisodecyl phosphite, trialkyl phosphites such as triisooctyl phosphite and tristearyl phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol-diphosphite, etc.; thioether compounds: pentaerythritol-tetrakis-(β-laurylthiopropionate), tetrakis[methylene-3-(dodecylthio)propionate], thiodipropionate]methane, bis[2-methyl-4-{3-n-alkylthiopropionyloxy}-5-t-butylphenyl] sulfide, dilauryl-3,3'-thiodipropionate, dimistyryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, pentaerythryl-tetrakis(3-laurylthiopropionate), ditridecyl-3,3'-thiodipropionate, 2-mercaptobenzimidazole, etc.; hindered amine compounds: dimethyl succinate, 1-(2-hydroxyethyl)-4-hydroxybenzoate Poly(2,2,6,6-tetramethylbenzyl)pyridine polycondensate, poly{[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]}, N,N'-bis(3-aminopropyl)ethylenediamine·2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-2-n-butylmalonate, etc.; Benzotriazole compounds: 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole Examples of antioxidants include azoles, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate-polyethylene glycol condensates, hydroxyphenylbenzotriazole derivatives, 2-[2-hydroxy-3-(3,4,5,6-tetra-hydrophthalimido-methyl)-5-methylphenyl]benzotriazole, and benzophenone compounds such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone. At least one of these can be selected. The antioxidants can be in any form, including powder, granules, liquid, paste, and emulsion.

[0120] Among these, hindered phenol-based antioxidants are preferred, and in particular, pentaerythritol-tetrakis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate are preferably used because they have an excellent effect of reducing thermal degradation of the resin composition of the present invention.

[0121] The content of the antioxidant is usually 0.001 to 10% by weight, preferably 0.005 to 5% by weight, and particularly preferably 0.01 to 3% by weight, based on the total weight of the resin composition.

[0122] Specific examples of the phosphoric acid and / or its salt include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, tricalcium phosphate, magnesium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, zinc hydrogen phosphate, barium hydrogen phosphate, manganese hydrogen phosphate, etc. These can be used alone or in combination of two or more. Among these, phosphoric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium dihydrogen phosphate, zinc hydrogen phosphate are preferred, phosphoric acid, sodium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium dihydrogen phosphate, and zinc hydrogen phosphate are particularly preferred, and phosphoric acid is particularly preferred.

[0123] The content of the phosphoric acid and / or its salt is usually preferably 0.001 to 300 ppm, more preferably 0.005 to 200 ppm, and even more preferably 0.01 to 100 ppm, based on the total amount of the resin composition.

[0124] Specific examples of the cinnamic acid and / or its salt include cis-cinnamic acid and trans-cinnamic acid, with trans-cinnamic acid being preferred from the standpoint of stability and cost. Examples of cinnamate salts include alkali metal cinnamates such as lithium cinnamate, sodium cinnamate, and potassium cinnamate, and alkaline earth metal cinnamates such as magnesium cinnamate, calcium cinnamate, and barium cinnamate. These cinnamic acids and / or their salts can be used alone or in combination of two or more. Of these, it is preferred to use trans-cinnamic acid alone.

[0125] The content of the cinnamic acid and / or its salt is usually 0.1 to 120 ppm, preferably 0.1 to 100 ppm, more preferably 1 to 80 ppm, and even more preferably 1.5 to 50 ppm, based on the total amount of the resin composition.

[0126] The conjugated polyene compound is a compound having two or more conjugated double bonds, i.e., a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately connected. The conjugated polyene compound may be a conjugated diene having two carbon-carbon double bonds and one carbon-carbon single bond alternately connected, a conjugated triene having three carbon-carbon double bonds and two carbon-carbon single bonds alternately connected, or a conjugated polyene compound having a structure in which a greater number of carbon-carbon double bonds and carbon-carbon single bonds are alternately connected. However, since a conjugated polyene compound having eight or more conjugated carbon-carbon double bonds may discolor molded articles due to the color of the conjugated polyene compound itself, polyenes having seven or fewer conjugated carbon-carbon double bonds are preferred. Furthermore, the conjugated double bonds consisting of two or more carbon-carbon double bonds may be present in a single molecule in a plurality of pairs that are not conjugated with each other. For example, compounds that contain three conjugated trienes in the same molecule, such as tung oil, are also included in conjugated polyene compounds.

[0127] Specific examples of conjugated polyene compounds include conjugated diene compounds having two carbon-carbon double bonds, such as isoprene, myrcene, farnesene, cembrene, sorbic acid, sorbic acid esters, sorbates, and abietic acid; conjugated triene compounds having three carbon-carbon double bonds, such as 1,3,5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, and cholecalciferol; and conjugated polyene compounds having four or more carbon-carbon double bonds, such as cyclooctatetraene, 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid. These conjugated polyene compounds may be used alone or in combination of two or more.

[0128] The content of the conjugated polyene compound is usually preferably 0.001 to 1000 ppm, more preferably 0.01 to 100 ppm, and particularly preferably 0.05 to 50 ppm, based on the total amount of the resin composition.

[0129] <Method of manufacturing resin composition> The method for producing the resin composition of the present invention is not particularly limited, and examples thereof include the following methods (I) to (IV). Note that the following methods (I) to (IV) may be used in combination. (I) A method (dry blending method) in which at least one of thermoplastic resin (B), EVOH (C), acetic acid and / or a salt thereof (D), aliphatic carboxylic acid (E), and a metal salt of aliphatic carboxylic acid (F) is mixed with pellets of thermoplastic resin (A) in a predetermined ratio and dry-blended. (II) A method (immersion method) in which pellets of at least one of thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) are immersed in a solution containing at least one of acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E), and a metal salt of an aliphatic carboxylic acid (F), and then the pellets are dried. (III) A method (melt-kneading method) in which at least one of thermoplastic resin (A), thermoplastic resin (B), EVOH (C), acetic acid and / or a salt thereof (D), aliphatic carboxylic acid (E), and a metal salt of an aliphatic carboxylic acid (F) is blended in a predetermined ratio, melt-kneaded, and then pelletized. (IV) A method in which at least one of acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E), and a metal salt of the aliphatic carboxylic acid (F) is added to a solution containing pellets of at least one of a thermoplastic resin (A), a thermoplastic resin (B), and an EVOH (C), and the mixture is mixed, and then the solvent in the solution is removed (solution mixing method).

[0130] Among these, the method (III) of blending at least one of thermoplastic resin (A), thermoplastic resin (B), EVOH (C), acetic acid and / or its salt (D), aliphatic carboxylic acid (E), and a metal salt of aliphatic carboxylic acid (F) in a predetermined ratio, melt-kneading, and then preparing pellets (melt-kneading method) is practical and industrially preferred in terms of productivity and economy. Furthermore, when blending other thermoplastic resins or additives, a resin composition containing other thermoplastic resins or additives can be obtained by following the methods (I) to (IV) above.

[0131] As a means for dry blending in the above method (I), known mixing devices such as a rocking mixer, ribbon blender, line mixer, etc. can be used.

[0132] In the dry blending in the above method (I), in order to improve the adhesion of at least one of the acetic acid and / or its salt (D), the aliphatic carboxylic acid (E), and the aliphatic carboxylic acid metal salt (F), it is preferable to adjust the moisture content of pellets of at least one of the thermoplastic resin (A), the thermoplastic resin (B), and the EVOH (C) to 0.1 to 5 wt. % (preferably 0.5 to 4 wt. %, particularly 1 to 3 wt. %). If the moisture content is too low, at least one of the acetic acid and / or its salt (D), the aliphatic carboxylic acid (E), and the aliphatic carboxylic acid metal salt (F) tends to easily fall off, resulting in non-uniform adhesion distribution. Conversely, if the moisture content is too high, at least one of the acetic acid and / or its salt (D), the aliphatic carboxylic acid (E), and the aliphatic carboxylic acid metal salt (F) tends to aggregate, resulting in non-uniform adhesion distribution.

[0133] The moisture content of the pellets of at least one of the thermoplastic resin (A), the thermoplastic resin (B) and the EVOH (C) is measured and calculated by the following method. [Method for measuring moisture content] Pellets of at least one of thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) are weighed on an electronic balance (W1: unit: g), placed in a hot air oven-type dryer maintained at 150°C, dried for 5 hours, and then allowed to cool in a desiccator for 30 minutes. The weight is then similarly weighed (W2: unit: g) and calculated using the following formula. [Formula] Moisture content (%)={(W1-W2) / W1}×100

[0134] The above methods (I) and (II) provide pellets having at least one component selected from the group consisting of the thermoplastic resin (A), the thermoplastic resin (B), and the EVOH (C) adhered to the outside of the pellets. The pellets have at least one component selected from the group consisting of the acetic acid and / or its salt (D), the aliphatic carboxylic acid (E), and the metal salt of the aliphatic carboxylic acid (F).

[0135] The melt-kneading in the above method (III) can be carried out using known melt-kneading devices such as kneaders, ruders, extruders, mixing rolls, Banbury mixers, and plastomills. Melt-kneading is typically performed at 150 to 300°C (more preferably 180 to 280°C) for approximately 1 to 20 minutes. The use of a single-screw or twin-screw extruder is particularly advantageous from an industrial perspective because pellets can be easily obtained. It is also preferable to provide a vent suction device, gear pump device, screen device, or the like, as needed. In particular, by providing one or more vent holes in the extruder and performing suction under reduced pressure to remove moisture and by-products (such as low-molecular-weight pyrolysis products), or by continuously supplying an inert gas such as nitrogen into the hopper to prevent oxygen from entering the extruder, a high-quality resin composition with reduced thermal discoloration and thermal degradation can be obtained.

[0136] Furthermore, there are no particular limitations on the method of supplying the mixture to a melt-kneading device such as an extruder. 1) A method in which the thermoplastic resin (A), the thermoplastic resin (B), the EVOH (C), the acetic acid and / or its salt (D), the aliphatic carboxylic acid (E), and the metal salt of the aliphatic carboxylic acid (F) are dry-blended and fed all at once to an extruder. 2) A method in which pellets of at least one of thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) are fed into an extruder and melted, and solid acetic acid and / or its salt (D), aliphatic carboxylic acid (E), and a metal salt of aliphatic carboxylic acid (F) are fed thereto (solid side feed method). 3) A method in which pellets of at least one of thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) are fed into an extruder and melted, and molten acetic acid and / or a salt thereof (D), aliphatic carboxylic acid (E), and a metal salt of aliphatic carboxylic acid (F) are then fed (melt side feed method). Among them, method 1) is practical in terms of the simplicity of the equipment and the cost of the blend.

[0137] From the viewpoint of reducing the environmental load, the following methods 4) to 6) are also preferred, in which scrap containing a layer made of a thermoplastic resin (A) and a layer made of an EVOH (C) is used as a raw material. 4) A method in which scrap containing a layer of thermoplastic resin (A) and a layer of EVOH (C) is dry-blended with thermoplastic resin (B), acetic acid and / or a salt thereof (D), aliphatic carboxylic acid (E), and a metal salt of aliphatic carboxylic acid (F), and the mixture is supplied to an extruder all at once. 5) A method in which pellets obtained by melt-kneading a thermoplastic resin (B), acetic acid and / or its salt (D), an aliphatic carboxylic acid (E), and a metal salt of an aliphatic carboxylic acid (F) are dry-blended with scrap containing a layer of a thermoplastic resin (A) and a layer of EVOH (C), and the resulting mixture is supplied to an extruder all at once. 6) A method in which scrap containing a layer made of a thermoplastic resin (A), acetic acid and / or a salt thereof (D), an aliphatic carboxylic acid (E), an aliphatic carboxylic acid metal salt (F), and an EVOH (C) are dry-blended with a thermoplastic resin (B) and fed all at once to an extruder can be exemplified. Among these, methods 4) and 6) are practical in terms of the simplicity of the equipment and cost.

[0138] The scrap refers to scraps or defective products collected during the production of a multilayer structure or a molded article, and the scrap may also be a multilayer structure containing a recycled layer containing scrap. That is, a multilayer structure or a molded article may be produced that contains a recycled layer made of a resin composition obtained from scraps or defective products generated during the production of the multilayer structure or the molded article, and the scrap from the multilayer structure or the molded article may be collected and used as a raw material for the resin composition of the present invention.

[0139] The scrap is preferably crushed to an appropriate size. The scrap may be scrap obtained from one type of multilayer structure and molded body, or a mixture of scraps obtained from two or more types of multilayer structures and molded bodies may be used.

[0140] Furthermore, the scrap may consist of multilayer structures and molded articles discarded by general consumers as plastic waste. That is, multilayer structures and molded articles discarded by general consumers as plastic waste may be collected, and the collected scrap of the multilayer structures and molded articles may be used as a raw material for the resin composition of the present invention.

[0141] Furthermore, as a method for producing pellets after melt-kneading, known methods can be used, such as a strand cut method, a hot cut method (air cut method, underwater cut method), etc. From the viewpoint of industrial productivity, the strand cut method is preferred.

[0142] The solvent used in the solution mixing method of method (IV) above may be any known good solvent. A typical good solvent for EVOH (C) is a mixed solvent of water and an aliphatic alcohol having 1 to 4 carbon atoms, preferably a mixed solvent of water and methanol. Heating and pressure can be applied as desired for dissolution, and the concentration can be any desired value. Acetic acid and / or its salt (D), an aliphatic carboxylic acid (E), and an aliphatic carboxylic acid metal salt (F) can be blended into a solution or paste containing pellets of at least one of thermoplastic resin (A), thermoplastic resin (B), and EVOH (C). The acetic acid and / or its salt (D), aliphatic carboxylic acid (E), and aliphatic carboxylic acid metal salt (F) can be blended in the form of a solid, solution, dispersion, or the like. After blending, the resin composition solution or paste is stirred uniformly and pelletized by the above-mentioned known method. From the viewpoint of industrial productivity, the underwater cutting method is preferred. The obtained pellets are dried by a known method.

[0143] The pellets may be in any shape, such as a sphere, oval, cylinder, cube, or rectangular parallelepiped. They are usually oval or cylindrical, and from the viewpoint of convenience when used later as a molding material, the size of the pellets is such that, in the case of an oval shape, the minor axis is usually 1 to 6 mm, preferably 2 to 5 mm, and the major axis is usually 1 to 6 mm, preferably 2 to 5 mm. In the case of a cylindrical shape, the diameter of the base is usually 1 to 6 mm, preferably 2 to 5 mm, and the length is usually 1 to 6 mm, preferably 2 to 5 mm.

[0144] In this manner, the resin composition of the present invention can be obtained.

[0145] <Molded body> The molded article of the present invention is produced by melt molding the resin composition of the present invention. The molded article can be used as it is in various shapes (for example, films, sheets, cups, trays, bottles, tanks, pipes, tubes, transport pallets, chairs, desks, stakes, etc.), but is optionally subjected to a (heated) stretching treatment. The stretching treatment may be either uniaxial or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous or sequential stretching. Stretching methods that achieve a high stretch ratio, such as roll stretching, tenter stretching, tubular stretching, stretch-blow, and vacuum / compressed air molding, can also be used. The stretching temperature is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, stretchability tends to be poor, and if it is too high, it tends to be difficult to maintain a stable stretched state.

[0146] The molded article may be heat-set to impart dimensional stability after stretching. Heat setting can be performed by known means, for example, by heat-treating the stretched multilayer structure (stretched film) while maintaining tension, usually at 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds.

[0147] Furthermore, when a single-layer stretched film obtained using the resin composition of the present invention is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting may not be carried out, but rather a treatment such as cooling and setting the stretched film by blowing cold air on it may be carried out.

[0148] Furthermore, it is also possible to obtain cup- or tray-shaped monolayer containers from the molded article of the present invention. As a method for producing a monolayer container, a drawing method is usually employed, specifically, vacuum forming, pressure forming, vacuum pressure forming, plug-assisted vacuum pressure forming, etc. Furthermore, when a tube- or bottle-shaped monolayer container is obtained from a monolayer parison (a hollow tubular preform before blowing), a blow molding method is employed, specifically, extrusion blow molding (e.g., double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, biaxial stretch blow molding (e.g., extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The molded article of the present invention may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, split processing, etc. as required.

[0149] The thickness of the molded article (including the stretched one) of the present invention is appropriately set depending on the application, packaging form, required physical properties, and the like.

[0150] The thickness of the molded article (including the stretched one) of the present invention is usually 10 to 500,000 μm, preferably 30 to 300,000 μm, and particularly preferably 50 to 200,000 μm. If the thickness of the molded article is too thin, the mechanical strength tends to decrease. On the other hand, if the thickness of the molded article is too thick, the mechanical strength will be excessive, which is economically undesirable because unnecessary raw materials will be used in excess.

[0151] In this manner, the molded article of the present invention can be obtained.

[0152] <Multilayer structure> The multilayer structure of the present invention has at least one layer made of the resin composition of the present invention. The layer made of the resin composition of the present invention (hereinafter simply referred to as "resin composition layer") can be laminated with another substrate to further increase strength or to impart other functions.

[0153] As the other substrate, a layer made of an adhesive resin (hereinafter simply referred to as an "adhesive resin layer"), a layer made of a polyamide-based resin (hereinafter simply referred to as a "polyamide layer"), a layer made of EVOH (C) (hereinafter simply referred to as an "EVOH layer"), or a layer made of a thermoplastic resin other than EVOH (hereinafter simply referred to as a "thermoplastic resin layer") is preferably used.

[0154] The layer structure of the multilayer structure is as follows: where R (R1, R2, ...) represents the resin composition layer of the present invention, α (α1, α2, ...) represents the EVOH layer, β (β1, β2, ...) represents the adhesive resin layer, γ (γ1, γ2, ...) represents the polyamide layer, and δ (δ1, δ2, ...) represent the thermoplastic resin layer. The layer structure is as follows: δ / R / β / α, α1 / R / α2 / α3, δ / R / α1 / β / α2, δ1 / R / α / β / δ2, R1 / α1 / β / α2 / R2, R1 / α1 / α2 / α Any combination is possible, such as 3 / R2, δ1 / R1 / β1 / α / β2 / R2 / δ2, δ1 / R1 / β1 / α1 / α2 / α3 / β2 / R2 / δ2, δ1 / R1 / α1 / β / α2 / R2 / δ2, δ / R / β / α / γ, δ / R / γ / α1 / β / α2, δ1 / R / γ / α / β / δ2, R1 / γ / α1 / β / α2 / R2, δ1 / R1 / β1 / γ / α / β2 / R2 / δ2, δ1 / R1 / γ1 / α1 / β / α2 / γ2 / R2 / δ2, etc. Furthermore, with respect to any EVOH layer (α), the structure of the layer laminated in one lamination direction and the structure of the layer laminated in the other lamination direction may be the same (symmetrical) or different (asymmetrical). Furthermore, with respect to any EVOH layer (α), the thickness of a layer laminated in one lamination direction and the thickness of a layer laminated in the other lamination direction may be the same (symmetric) or different (asymmetric).

[0155] As the polyamide-based resin, known ones can be used. Specific examples include homopolymers such as polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), and polylauryllactam (nylon 12). Among these, polycapramide (nylon 6) is preferred. Furthermore, examples of copolymer polyamide-based resins include polyethylenediamineadipamide (nylon 26), polytetramethyleneadipamide (nylon 46), polyhexamethyleneadipamide (nylon 66), polyhexamethylenesebacamide (nylon 610), polyhexamethylenedodecamide (nylon 612), polyoctamethyleneadipamide (nylon 86), polydecamethyleneadipamide (nylon 108), caprolactam, and the like. / Lauryl lactam copolymer (nylon 6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 66), lauryllactam / hexamethylenediammonium adipate copolymer (nylon 12 / 66), ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon 26 / 66), Examples of suitable polyamides include aliphatic polyamides such as caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 66 / 610) and ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 66 / 610), aromatic polyamides such as polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymetaxylylene adipamide, hexamethylene isophthalamide / terephthalamide copolymer, poly-p-phenylene terephthalamide, and poly-p-phenylene-3,4'-diphenyl ether terephthalamide, amorphous polyamides, and polyamide-based resins modified with aromatic amines such as methylenebenzylamine and metaxylylenediamine, metaxylylenediammonium adipate, etc. Alternatively, these polyamide-based resins may be terminally modified, preferably terminally modified polyamide-based resins.

[0156] Examples of thermoplastic resins other than EVOH include polyethylene-based resins such as linear low-density polyethylene, low-density polyethylene, very low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, and ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene-based resins such as polypropylene and propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin-based resins such as polybutene, polypentene, and polycyclic olefin-based resins (polymers having a cyclic olefin structure in the main chain and / or side chain); Examples of the polyolefin resins include polyolefin resins in the broad sense, including modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins obtained by graft-modifying the above polyolefins with unsaturated carboxylic acids or their esters, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, etc. These may be used alone or in combination of two or more.

[0157] Of these, in consideration of hydrophobicity, hydrophobic resins such as polyolefin resins, polyester resins, and polystyrene resins are preferred, and more preferred are polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof, with polycyclic olefin resins being particularly preferred as hydrophobic resins.

[0158] The ethylene and α-olefins in the polyolefin resins may be plant-derived ethylene and α-olefins derived from bioethanol, or non-plant-derived, i.e., petroleum-derived ethylene and α-olefins, or a combination of two of these may be used. Because a wide variety of petroleum-derived α-olefins are available, the physical properties of the polyolefin resin can be easily adjusted by using these in production. Furthermore, the use of plant-derived ethylene and α-olefins can further increase the biomass content of the final product, thereby reducing the burden on the environment.

[0159] A conventional method for producing plant-derived ethylene and α-olefins involves fermenting sugar solutions or starch obtained from plants such as sugarcane, corn, and sweet potato using microorganisms such as yeast to produce bioethanol, which is then heated in the presence of a catalyst to obtain plant-derived ethylene and α-olefins (1-butene, 1-hexene, etc.) through intramolecular dehydration or the like. The resulting plant-derived ethylene and α-olefins can then be used to produce plant-derived polyethylene resins in the same manner as in the production of petroleum-derived polyethylene resins.

[0160] Methods for producing plant-derived ethylene, α-olefins, and plant-derived polyethylene resins are described in detail, for example, in JP-A No. 2011-506628, etc. Examples of plant-derived polyethylene resins that can be suitably used in the present invention include Green PE manufactured by Braskem SA.

[0161] The adhesive resin used to form the adhesive resin layer can be any known adhesive resin, and can be selected appropriately depending on the type of thermoplastic resin used in the other thermoplastic resin substrate. Representative examples include carboxyl-containing modified polyolefin polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin via addition reaction, graft reaction, or the like. Examples include maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-propylene (block and random) copolymers, maleic anhydride-grafted ethylene-ethyl acrylate copolymers, maleic anhydride-grafted ethylene-vinyl acetate copolymers, maleic anhydride-grafted polycyclic olefin resins, and maleic anhydride-grafted polyolefin resins. These can be used alone or in combination of two or more.

[0162] The content of the unsaturated carboxylic acid or its anhydride in the carboxyl group-containing modified polyolefin polymer is usually 0.001 to 3 wt %, preferably 0.01 to 1 wt %, and particularly preferably 0.03 to 0.5 wt %, based on the total amount of the carboxyl group-containing modified polyolefin polymer. If the content (modification amount) of the unsaturated carboxylic acid or its anhydride is low, the adhesiveness tends to be insufficient, whereas if it is high, a crosslinking reaction tends to occur, resulting in poor moldability. These adhesive resins can be blended with rubber elastomer components such as ethylene-vinyl alcohol copolymer, polyisobutylene, ethylene-propylene rubber, and even resins for polyolefin resin layers. In particular, it is possible to blend a polyolefin resin different from the base polyolefin resin of the adhesive resin.

[0163] The adhesive resin layer, polyamide layer, and thermoplastic resin layer may contain, within a range that does not impair the gist of the present invention (for example, 30% by weight or less, preferably 10% by weight or less), acetic acid and / or its salt (D), aliphatic carboxylic acid (E), and aliphatic carboxylic acid metal salt (F) used in the present invention, as well as conventionally known plasticizers (for example, ethylene glycol, glycerin, hexanediol, etc.), fillers, clays (for example, montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants (for example, alkali metal salts and alkaline earth metal salts of higher fatty acids having 8 to 30 carbon atoms, higher fatty acid esters (for example, methyl esters of higher fatty acids, isopropyl alcohol, etc.), and the like. propyl ester, butyl ester, octyl ester, etc.), higher fatty acid amides (for example, saturated fatty amides such as stearic acid amide and behenic acid amide, unsaturated fatty acid amides such as oleic acid amide and erucic acid amide, bisfatty acid amides such as ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, ethylene bislauric acid amide, etc.), low molecular weight polyolefins (for example, low molecular weight polyethylene or low molecular weight polypropylene having a molecular weight of about 500 to 10,000), fluorinated ethylene resins, nucleating agents, antiblocking agents, ultraviolet absorbers, waxes, etc. These may be used alone or in combination of two or more.

[0164] It is also preferable to blend at least one selected from the group consisting of the thermoplastic resin (A), the thermoplastic resin (B), EVOH (C), acetic acid and / or its salt (D), aliphatic carboxylic acid (E), and aliphatic carboxylic acid metal salt (F) with the resin used in the adhesive resin layer and / or polyamide layer.

[0165] The lamination method when the resin composition layer is laminated with the other substrate to prepare a multilayer structure can be carried out by a known method.For example, the method of melt-extrusion laminating the other substrate onto a film, sheet, etc. made of the resin composition of the present invention, the method of melt-extrusion laminating the resin composition of the present invention onto the other substrate, the method of co-extrusion molding the resin composition of the present invention and the other substrate, the method of preparing a film (layer) made of the resin composition of the present invention and the other substrate (layer), and then dry laminating them using known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, polyurethane compounds, etc., the method of applying a solution of the resin composition of the present invention onto the other substrate and then removing the solvent, etc.Among these, the co-extrusion molding method is preferred from the viewpoints of cost and environment.

[0166] The multilayer structure is then subjected to a (heat) stretching treatment as needed. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Furthermore, the stretching method may be a roll stretching method, tenter stretching method, tubular stretching method, stretch-blow method, vacuum pressure forming method, or the like, whichever provides a higher stretch ratio. The stretching temperature is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, poor stretchability results, and if it is too high, it becomes difficult to maintain a stable stretched state.

[0167] For the purpose of imparting dimensional stability after stretching, heat setting may be carried out subsequently. Heat setting can be carried out by known means, for example, by subjecting the stretched multilayer structure (stretched film) to heat treatment usually at 80 to 180°C, preferably 100 to 165°C, for usually 2 to 600 seconds while maintaining tension.

[0168] Furthermore, when the multilayer stretched film obtained using the resin composition of the present invention is used as a shrink film, in order to impart heat shrinkability, the above-mentioned heat setting may not be carried out, but rather a treatment such as cooling and setting the stretched film by blowing cold air on it may be carried out.

[0169] Furthermore, in some cases, it is also possible to obtain cup- or tray-shaped multilayer containers from the multilayer structure of the present invention. As a method for producing multilayer containers, a drawing method is usually used, specifically vacuum forming, pressure forming, vacuum pressure forming, plug-assisted vacuum pressure forming, etc. Furthermore, when a tube- or bottle-shaped multilayer container is obtained from a multilayer parison (a hollow tubular preform before blowing), a blow molding method is used, specifically extrusion blow molding (e.g., double-head, mold-moving, parison-shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, biaxial stretch blow molding (e.g., extrusion cold parison biaxial stretch blow molding, injection cold parison biaxial stretch blow molding, injection molding in-line biaxial stretch blow molding, etc.). The multilayer laminate of the present invention may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, splitting processing, etc. as required.

[0170] The thickness of the multilayer structure of the present invention (including a stretched structure), and further the thickness of the resin composition layer, EVOH layer, polyamide resin layer, adhesive resin layer, and other thermoplastic resin layer that constitute the multilayer structure, are set appropriately depending on the layer configuration, the type of thermoplastic resin, the type of polyamide resin, the type of adhesive resin, the intended use, the form of packaging, the required physical properties, and the like.

[0171] The total thickness of the multilayer structure (including the stretched one) of the present invention is usually 10 to 5000 μm, preferably 30 to 3000 μm, and particularly preferably 50 to 2000 μm. If the total thickness of the multilayer structure is too thin, the gas barrier property and mechanical strength may be reduced. On the other hand, if the total thickness of the multilayer structure is too thick, the gas barrier property and mechanical strength may become excessive, resulting in the use of unnecessary extra raw materials, which tends to be uneconomical. The resin composition layer (R) is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, and particularly preferably 20 to 1,000 μm, the EVOH layer (α) is usually 1 to 500 μm, preferably 3 to 300 μm, and particularly preferably 5 to 200 μm, the thermoplastic resin layer (δ) is usually 5 to 3,000 μm, preferably 10 to 2,000 μm, and particularly preferably 20 to 1,000 μm, and the adhesive resin layer (β) is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm. When two or more layers of at least one of the resin composition layer (R), EVOH layer (α), adhesive resin layer (β), and thermoplastic resin layer (δ) are present, the above numerical values ​​refer to the total thickness of the layers of the same type.

[0172] Furthermore, the thickness ratio of the EVOH layer (α) to the resin composition layer (R) in the multilayer structure (EVOH layer (α) / resin composition layer (R)), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 1 / 99 to 50 / 50, preferably 2 / 98 to 45 / 55, particularly preferably 5 / 95 to 40 / 60, and especially preferably 10 / 90 to 35 / 65. When this value is within the above range, the effects of the present invention tend to be more pronounced. When the value is below the above range, the gas barrier properties and mechanical strength tend to be insufficient, and when the value is above the above range, the multilayer structure tends to be more susceptible to cracking.

[0173] Furthermore, the thickness ratio of the EVOH layer (α) to the polyamide layer (γ) in the multilayer structure (EVOH layer (α) / polyamide layer (γ)), ​​expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 80 / 20, and particularly preferably 40 / 60 to 60 / 40. When this value is within the above range, the effects of the present invention tend to be more pronounced, while when it is less than the above range, the gas barrier properties tend to be insufficient, and when it is greater than the above range, the mechanical strength tends to be insufficient.

[0174] Furthermore, the thickness ratio of the EVOH layer (α) to the adhesive resin layer (β) in the multilayer structure (EVOH layer (α) / adhesive resin layer (β)), expressed as the ratio between the thickest layers when there are multiple layers of each type, is usually 10 / 90 to 99 / 1, preferably 20 / 80 to 95 / 5, and particularly preferably 50 / 50 to 90 / 10. When this value is within the above range, the effects of the present invention tend to be more pronounced, while when it is less than the above range, the gas barrier properties tend to be insufficient, and when it is greater than the above range, the adhesive strength tends to be insufficient.

[0175] A multilayer structure containing a layer made of the above-mentioned resin composition is useful as a raw material for various packaging materials for general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, etc. [Example]

[0176] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0177] Prior to the examples, the following ingredients were prepared:

[0178] [Thermoplastic resin (A)] Polypropylene (a1) (Japan Polypropylene "EA7AD", MFR 1.4g / 10min [230℃, load 2160g])

[0179] [Thermoplastic resin (B)] Maleic anhydride grafted modified polypropylene (b1) (LyondellBasell "PLEXAR PX6002", MFR 2.3 g / 10 min [230°C, load 2160 g]) Polyvinyl acetate resin (b2) [ethylene-vinyl acetate copolymer (b3) [Ultrathene 3B53A manufactured by Tosoh Corporation, vinyl acetate content: 28 wt%, MFR: 5.7 g / 10 min (190°C, load 2160 g)] and saponified ethylene-vinyl acetate copolymer (b4) [Mersene H0051K manufactured by Tosoh Corporation, ethylene content: 89 mol%, saponification degree: 99 mol%, MFR: 6.5 g / 10 min (190°C, load 2160 g)], melt-kneaded in a weight ratio of (b3) / (b4) = 97.8 / 2.2.

[0180] [EVOH(C)] EVOH (c1) [ethylene structural unit content 29 mol%, saponification degree 99.7 mol%, MFR 3.8 g / 10 min (210 °C, load 2160 g)] EVOH (c2) [ethylene structural unit content 29 mol%, saponification degree 99.7 mol%, MFR 8.0 g / 10 min (210°C, load 2160 g)]

[0181] [Acetic acid and / or its salts (D)] Sodium acetate (d1)

[0182] [Aliphatic carboxylic acid (E)] Stearic acid (e1) Caprylic acid (e2) Lauric acid (e3) Behenic acid (e4)

[0183] [Aliphatic carboxylic acid metal salt (F)] Zinc stearate (f1) Zinc caprylate (F2) Zinc laurate (f3) Zinc behenate (f4) Magnesium stearate (F5) Sodium stearate (F6) Zinc gluconate trihydrate (f7) Zinc citrate dihydrate (f8) [Example 1] [Production of Resin Composition] Polypropylene (a1) pellets were used as the thermoplastic resin (A) not containing polar groups, maleic anhydride graft-modified polypropylene (b1) pellets were used as the thermoplastic resin (B) containing polar groups, EVOH (c1) pellets were used as the EVOH (C), sodium acetate (d1) was used as the acetic acid and / or its salt (D), stearic acid (e1) was used as the aliphatic carboxylic acid (E), and zinc stearate (f1) was used as the aliphatic carboxylic acid metal salt (F). The resin composition was prepared by dry-blending the above polypropylene (a1) in an amount of 94% by weight based on the total weight of the resin composition, maleic anhydride-grafted polypropylene (b1) in an amount of 1% by weight based on the total weight of the resin composition, EVOH (c1) in an amount of 5% by weight based on the total weight of the resin composition, sodium acetate (d1) in an amount of 22 ppm in terms of acetate ions based on the total weight of the resin composition, stearic acid (e1) in an amount of 0.02 ppm in terms of carboxylate ions based on the total weight of the resin composition, and zinc stearate (f1) in an amount of 0.5 ppm in terms of metal ions based on the total weight of the resin composition, all at once. The resulting mixture was then melt-kneaded under the following melt-kneading conditions using a φ32 mm twin-screw extruder (L / D=56, molding temperature=210°C) and re-pelletized to prepare the resin composition.

[0184] [Conditions for melt-kneading resin composition] Twin-screw extruder: diameter 32 mm, L / D=56 (Made by Nippon Steel) ·Extruder setting temperature: C2 / C3 / C4 / C5 / C6 / C7 / C8 / C9 / C10 / C11 / C12 / C13 / C14 / C15 / C16 / H / D=100 / 15 0 / 200 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210℃ Screw speed: 330ppm ·Discharge amount: 25kg / hour Strand cooling: water cooling

[0185] <Evaluation of mechanical strength of resin composition> The resin composition prepared above was hot-press molded at 230°C using a manual hydraulic vacuum heating press (MIC-1867) manufactured by Imoto Manufacturing Co., Ltd. to produce a 1 mm thick monolayer sheet. The resulting monolayer sheet was then cut into strip-shaped test specimens measuring 1 mm thick, 15 mm wide, and 100 mm long. The strip-shaped test specimens prepared above were subjected to tensile testing at 23°C and 50% RH using a Shimadzu Autograph AGS-X tensile tester with a 50 mm gauge length and a test speed of 50 mm / min to evaluate the modulus of elasticity and breaking strain. This evaluation was performed five times, and the average values ​​were calculated. Higher values ​​for modulus of elasticity and breaking strain indicate superior mechanical strength of the resin composition.

[0186] [Example 2] A resin composition was prepared in the same manner as in Example 1, except that stearic acid (e1) was used in an amount of 0.11 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc stearate (f1) was used in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0187] [Example 3] A resin composition was prepared in the same manner as in Example 1, except that the polypropylene (a1) was 90% by weight, the maleic anhydride graft-modified polypropylene (b1) was 1% by weight, and further, as the thermoplastic resin (B), polyvinyl acetate resin (b2) pellets were 4% by weight, the EVOH (c1) was 5% by weight, the sodium acetate (d1) was 22 ppm in terms of acetate ions, the stearic acid (e1) was 0.11 ppm in terms of carboxylate ions, and the zinc stearate (f1) was 2.3 ppm in terms of metal ions, based on the total resin composition. The resin composition was evaluated in the same manner as in Example 1.

[0188] [Example 4] A resin composition was prepared in the same manner as in Example 1, except that the amount of stearic acid (e1) was 0.45 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and the amount of zinc stearate (f1) was 9.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0189] [Example 5] The procedure was repeated in Example 1, except that caprylic acid (e2) was used instead of stearic acid (e1) in an amount of 0.06 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc caprylate (f2) was used instead of zinc stearate (f1) in an amount of 0.5 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0190] [Example 6] In Example 5, the procedure was repeated except that caprylic acid (e2) was used in an amount of 0.31 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc caprylate (f2) was used in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0191] [Example 7] In Example 3, the procedure was repeated except that caprylic acid (e2) was used instead of stearic acid (e1) in an amount of 0.31 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc caprylate (f2) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0192] [Example 8] In Example 5, the same procedure was carried out as in Example 1, except that the amount of caprylic acid (e2) was 1.28 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and the amount of zinc caprylate (f2) was 9.3 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0193] [Example 9] A resin composition was prepared in the same manner as in Example 1, except that lauric acid (e3) was used instead of stearic acid (e1) in an amount of 0.02 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc laurate (f3) was used instead of zinc stearate (f1) in an amount of 0.5 ppm in terms of metal ion relative to the total amount of the resin composition. The resin composition was then evaluated in the same manner as in Example 1.

[0194] [Example 10] In Example 9, the same procedure was carried out as in Example 1, except that the amount of lauric acid (e3) was 0.08 ppm in terms of carboxylate ion relative to the total amount of the resin composition, and the amount of zinc laurate (f3) was 2.3 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0195] [Example 11] In Example 3, the same procedures were carried out except that stearic acid (e1) was replaced with lauric acid (e3) in an amount of 0.08 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc stearate (f1) was replaced with zinc laurate (f3) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0196] [Example 12] In Example 9, the same procedure was carried out as in Example 1, except that the amount of lauric acid (e3) was 0.33 ppm in terms of carboxylate ion relative to the total amount of the resin composition, and the amount of zinc laurate (f3) was 9.3 ppm in terms of metal ion relative to the total amount of the resin composition. A resin composition was prepared and evaluated in the same manner as in Example 1.

[0197] [Example 13] A resin composition was prepared in the same manner as in Example 1, except that behenic acid (E4) was used instead of stearic acid (E1) in an amount of 0.03 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc behenate (E4) was used instead of zinc stearate (F1) in an amount of 0.5 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0198] [Example 14] A resin composition was prepared in the same manner as in Example 13, except that the amount of behenic acid (e4) was 0.13 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and the amount of zinc behenate (f4) was 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0199] [Example 15] A resin composition was prepared in the same manner as in Example 3, except that behenic acid (e4) was used instead of stearic acid (e1) in an amount of 0.13 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and zinc behenate (f4) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0200] [Example 16] A resin composition was prepared in the same manner as in Example 13, except that the amount of behenic acid (e4) was 0.53 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and the amount of zinc behenate (f4) was 9.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0201] [Example 17] A resin composition was prepared in the same manner as in Example 1, except that stearic acid (e1) was used in an amount of 0.69 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and magnesium stearate (f5) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0202] [Example 18] A resin composition was prepared in the same manner as in Example 3, except that stearic acid (e1) was used in an amount of 0.69 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and magnesium stearate (f5) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0203] [Example 19] A resin composition was prepared in the same manner as in Example 1, except that stearic acid (E1) was used in an amount of 0.15 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and sodium stearate (E6) was used instead of zinc stearate (F1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0204] [Example 20] A resin composition was prepared in the same manner as in Example 3, except that stearic acid (e1) was used in an amount of 0.15 ppm in terms of carboxylic acid ion relative to the total amount of the resin composition, and sodium stearate (f6) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0205] [Comparative Example 1] A resin composition was prepared in the same manner as in Example 1, except that stearic acid (e1) and zinc stearate (f1) were not used, and was evaluated in the same manner as in Example 1.

[0206] Comparative Example 2 A resin composition was prepared in the same manner as in Example 3, except that stearic acid (e1) and zinc stearate (f1) were not used, and evaluated in the same manner as in Example 1.

[0207] Comparative Example 3 A resin composition was prepared in the same manner as in Example 2, except that stearic acid (e1) was not used, and was evaluated in the same manner as in Example 1.

[0208] Comparative Example 4 A resin composition was prepared in the same manner as in Example 5, except that the polypropylene (a1) was 69% by weight, the EVOH (c1) was 30% by weight, the sodium acetate (d1) was 130 ppm in acetate ion equivalent, the caprylic acid (e2) was 7.7 ppm in carboxylic acid ion equivalent, the zinc caprylate (f2) was 55.8 ppm in metal ion equivalent, the resin composition was evaluated in the same manner as in Example 1.

[0209] Comparative Example 5 A resin composition was prepared in the same manner as in Example 7, except that the polypropylene (a1) was 65% by weight, the EVOH (c1) was 30% by weight, the sodium acetate (d1) was 130 ppm in acetate ion equivalent, the caprylic acid (e2) was 7.7 ppm in carboxylic acid ion equivalent, the zinc caprylate (f2) was 55.8 ppm in metal ion equivalent, the resin composition was evaluated in the same manner as in Example 1.

[0210] Comparative Example 6 A resin composition was prepared in the same manner as in Example 1, except that stearic acid (e1) was used in an amount of 0.11 ppm in terms of carboxylate ion relative to the total amount of the resin composition, and zinc gluconate trihydrate (f7) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0211] Comparative Example 7 A resin composition was prepared in the same manner as in Example 3, except that zinc stearate (f1) was replaced with zinc gluconate trihydrate (f7), and the amount was 2.3 ppm in terms of metal ions relative to the total amount of the resin composition. The resin composition was then evaluated in the same manner as in Example 1.

[0212] [Comparative Example 8] A resin composition was prepared in the same manner as in Example 1, except that stearic acid (e1) was used in an amount of 0.11 ppm in terms of carboxylate ion relative to the total amount of the resin composition, and zinc citrate dihydrate (f8) was used instead of zinc stearate (f1) in an amount of 2.3 ppm in terms of metal ion relative to the total amount of the resin composition, and the resin composition was evaluated in the same manner as in Example 1.

[0213] Comparative Example 9 A resin composition was prepared in the same manner as in Example 6, except that EVOH (c2) was used instead of EVOH (c1) and sodium acetate (d1) was not used, and was evaluated in the same manner as in Example 1.

[0214] The evaluation results of the Examples and Comparative Examples are shown in Tables 1 and 2.

[0215] [Table 1]

[0216] [Table 2]

[0217] The resin compositions of Comparative Examples 1 to 9, which do not have the characteristic features of the present invention, had low mechanical strength. In contrast, the resin compositions of Examples 1 to 20 having the characteristic features of the present invention had excellent mechanical strength.

[0218] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention. [Industrial Applicability]

[0219] The resin composition of the present invention has excellent mechanical strength, and therefore, multilayer structures and molded articles containing layers of the resin composition are useful as raw materials for various packaging materials for general foods, as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, etc.

Claims

1. A resin composition comprising: (A) a thermoplastic resin not containing a polar group; (B) a thermoplastic resin containing a polar group; (C) an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol %; (D) acetic acid and / or a salt thereof; (E) an aliphatic carboxylic acid having 3 or more carbon atoms; and (F) an aliphatic carboxylic acid metal salt which is a metal salt of the aliphatic carboxylic acid (E), the thermoplastic resin (A) containing no polar group is at least one selected from the group consisting of a polyolefin resin and a polystyrene resin containing no hydroxyl group, no carboxy group, no amino group, and no amide group; the thermoplastic resin (B) containing a polar group is at least one selected from the group consisting of a modified polyolefin resin and a polyvinyl acetate resin, each containing a carboxy group or an acid anhydride group; A resin composition characterized in that the content of the thermoplastic resin (A) not containing a polar group is 66 to 99 wt % based on the total weight of the resin composition, and the content of the ethylene-vinyl alcohol copolymer (C) having an ethylene content of 20 to 60 mol % is 0.1 to 25 wt % based on the total weight of the resin composition.

2. The resin composition according to claim 1, characterized in that the thermoplastic resin (A) containing no polar groups is at least one selected from polyethylene, polypropylene, and polystyrene, which does not contain a hydroxyl group, a carboxy group, an amino group, or an amide group.

3. 3. The resin composition according to claim 1, wherein the content of the thermoplastic resin (B) containing a polar group is 0.1 to 25% by weight based on the total weight of the resin composition.

4. The resin composition according to any one of claims 1 to 3, characterized in that the content of the acetic acid and / or its salt (D) in terms of acetate ions is 0.01 to 1000 ppm with respect to the total of the resin composition.

5. The resin composition according to any one of claims 1 to 4, characterized in that the content of the aliphatic carboxylic acid (E) in terms of carboxylate ions is 0.0001 to 150 ppm relative to the total amount of the resin composition.

6. The resin composition according to any one of claims 1 to 5, characterized in that the content of the aliphatic carboxylic acid metal salt (F) in terms of metal ions is 0.01 to 90 ppm with respect to the total amount of the resin composition.

7. A method for producing a resin composition, comprising melt-kneading the resin composition according to any one of claims 1 to 6 and pelletizing the mixture.

8. A molded article using the resin composition according to any one of claims 1 to 6.

9. A multilayer structure comprising at least one layer made of the resin composition according to any one of claims 1 to 6.

10. A package comprising the multilayer structure according to claim 9.

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