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

Abstract

Provided is a resin composition preventing discoloration and mechanical strength reduction of a molded article, limiting fish eye generation and from which a molded product with superior appearance can be 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 aliphatic carboxylic acid (D) which 3 or more carbon atoms; and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D). The metal species (E) is at least one element among the elements of the d-block of the period 4 in the long-form periodic table, 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 non-polar group-containing thermoplastic resin, a polar group-containing thermoplastic resin, an ethylene-vinyl alcohol copolymer having an ethylene content of 20 to 60 mol% (hereinafter sometimes referred to as "EVOH"), an aliphatic carboxylic acid other than acetic acid, and an aliphatic carboxylic acid metal salt which is a metal salt of the above aliphatic carboxylic acid. More specifically, the present invention relates to a resin composition having excellent mechanical strength, and also excellent color tone stability and moldability.

Background Art

[0002] Conventionally, a laminate including a non-polar group-containing thermoplastic resin layer such as polyethylene and polypropylene, and a layer made of EVOH having excellent gas barrier properties (hereinafter sometimes abbreviated as "EVOH layer") is formed into a film, sheet, cup, tray, bottle, etc., and is applied to various uses by taking advantage of its characteristics, and is particularly commercially used as a packaging material for foods and pharmaceuticals. When manufacturing the above-mentioned molded article using such a laminate including a non-polar group-containing thermoplastic resin layer and an EVOH layer, scraps such as unnecessary parts such as scraps and ends, defective products, or garbage after using the molded article for various uses are generated. Such scraps amount to 30 to 50% (area ratio) of the original laminate. Therefore, the scraps are collected, melt-molded, and the recovered material may be reused as at least one layer of the laminate as a recycled layer (a so-called reground layer, which may be referred to as the "reground layer" in the present invention).

[0003] In recent years, activities for reducing waste plastic garbage have become active, and waste of used containers made of the above-mentioned molded articles discharged from ordinary households may be collected, melt-molded, and reused as recycled molded articles such as films, sheets, cups, trays, and bottles. Such recycling technology is industrially useful in terms of waste reduction and economy, and has been put into practical use.

[0004] However, since the compatibility between a thermoplastic resin that does not contain a polar group and EVOH is poor, when recycling the recovered product of a laminate having a thermoplastic resin layer that does not contain a polar group and an EVOH layer by remelting it into a regrind layer or a recycled molded article, the thermoplastic resin that does not contain a polar group and EVOH cause poor compatibility during melting, resulting in the generation of phase-separated foreign substances (eye gloss), and these foreign substances often mix into the molded article. Therefore, for example, it has caused appearance defects such as the occurrence of fish eyes or holes in the molded article, or the generation of wavy patterns on the surface.

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

[0006] Specifically, the saponified product of EVA with a high ethylene content has a feature that the ethylene content is 70 mol% or more and it has high compatibility with polyolefin. On the other hand, the above-mentioned EVOH is also a saponified product of EVA, but it has a feature that the ethylene content is 20 to 60 mol% and it has excellent gas barrier properties.

[0007] When the present inventors tried the methods described in Patent Documents 1 to 3 above, although these techniques can obtain relatively good results for the problems associated with the low compatibility between the thermoplastic resin that does not contain a polar group and EVOH, they found that there is a problem that the obtained regrind layer changes color to yellow or red. Therefore, in order to suppress such discoloration, the present inventors also tried a method of reducing the content of the saponified product of EVA with a high ethylene content, but the compatibilizing effect decreased, and the improvement of the problems associated with poor compatibility (generation of eye gloss, appearance defects, and decrease in mechanical strength) became insufficient, so further improvement is required.

[0008] On the other hand, as a modifier for improving the poor compatibility of the regrind layer, a resin composition based on a resin in which EVA and an EVA saponified product with a high ethylene content are used in combination has also been proposed (see Patent Document 4). However, even when using this resin composition, there is still room for improvement with respect to the above-mentioned discoloration problem and mechanical strength reduction problem.

[0009] In addition, in order to improve the compatibility that causes the above-mentioned eye varnish generation and appearance defects, a technique of blending a thermoplastic resin containing a polar group such as maleic anhydride-modified polyethylene and maleic anhydride-modified polypropylene is known (see Patent Document 5). However, even when using this resin composition, there is still room for improvement with respect to the above-mentioned discoloration problem and mechanical strength reduction problem.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Disclosure of the Invention

Problems to be Solved by the Invention

[0011] The present invention has been made in view of such circumstances, and even when scraps such as unnecessary parts and defective products of products generated during the production of a laminate containing a non-polar group-containing thermoplastic resin, a polar group-containing thermoplastic resin, and EVOH, or recyclables such as garbage after using the molded product for various purposes are reused as a resin composition, it is possible to prevent a decrease in mechanical strength and discoloration, suppress the generation of surface gloss, and provide a resin composition, a method for producing the resin composition, a molded body, a multilayer structure, and a package having excellent appearance.

Means for Solving the Problems

[0012] However, as a result of intensive studies by the present inventors in view of such circumstances, by using in combination a non-polar group-containing thermoplastic resin (A), a polar group-containing thermoplastic resin (B), EVOH (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) containing a specific metal species, which is a metal salt of the aliphatic carboxylic acid (D), it has been found that a resin composition excellent in mechanical strength and color tone stability and highly suppressing the generation of surface gloss during melt molding can be obtained.

[0013] That is, generally, it is known that an aliphatic carboxylic acid metal salt promotes the thermal decomposition of EVOH and deteriorates the mechanical strength and color tone of a resin composition containing EVOH. Therefore, when aiming to improve the mechanical strength and color tone of a resin composition containing EVOH, those skilled in the art avoid blending an aliphatic carboxylic acid metal salt. However, when the present inventors used in combination a non-polar group-containing thermoplastic resin, a polar group-containing thermoplastic resin, EVOH, an aliphatic carboxylic acid having 3 or more carbon atoms, and its specific metal salt so as to satisfy a specific relationship, it has been found that the mechanical strength and color tone are improved contrary to the conventional expectation.

[0014] Thus, the present invention relates to a resin composition containing a thermoplastic resin (A) not containing a polar group, a thermoplastic resin (B) containing a polar group, EVOH (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one selected from elements belonging to the d-block of the fourth period of the long-period type periodic table, the content of the thermoplastic resin (A) not containing a polar group is 66 to 99% by weight based on the total of the resin composition, and the content of the EVOH (C) is 0.1 to 25% by weight based on the total of the resin composition. This is the first gist of the invention.

[0015] Further, a method for producing a resin composition by melt-kneading and pelletizing the resin composition of the first gist is the second gist, a molded article using the resin composition of the first gist is the third gist, a multilayer structure having at least one layer made of the resin composition of the first gist is the fourth gist, and a packaging body made of the multilayer structure of the fourth gist is the fifth gist.

Effects of the Invention

[0016] The resin composition of the present invention is a resin composition containing a thermoplastic resin (A) not containing a polar group, a thermoplastic resin (B) containing a polar group, EVOH (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the aliphatic carboxylic acid (D), wherein the metal species of the aliphatic carboxylic acid metal salt (E) is at least one selected from elements belonging to the d-block of the fourth period of the long-period type periodic table, the content of the thermoplastic resin (A) not containing a polar group is 66 to 99% by weight based on the total of the resin composition, and the content of the EVOH (C) is 0.1 to 25% by weight based on the total of the resin composition. Therefore, it is excellent in mechanical strength and color tone stability, and the generation of surface gloss during melt molding is highly suppressed.

[0017] Further, when the thermoplastic resin (A) not containing a polar group is at least one selected from polyolefin resins and polystyrene resins, it is more excellent in recyclability and economy.

[0018] Moreover, when the thermoplastic resin (A) not containing the polar group is at least one selected from polyethylene, polypropylene, and polystyrene, it is further excellent in recyclability and economy.

[0019] Moreover, when the content of the thermoplastic resin (B) containing the polar group is 0.1 to 50% by weight based on the total of the resin composition, it is more excellent in mechanical strength, recyclability, and economy.

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

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

[0022] Moreover, when the content of the aliphatic carboxylic acid (D) having 3 or more carbon atoms in terms of carboxylic acid ions is 0.0001 to 150 ppm based on the total of the resin composition, it is more excellent in color tone stability.

[0023] Moreover, when the content of the aliphatic carboxylic acid metal salt (E) in terms of metal ions is 0.01 to 90 ppm based on the total of the resin composition, it is more excellent in mechanical strength, color tone stability, and moldability (stripe prevention).

[0024] Moreover, when further containing acetic acid and / or its salt (F), and the content of acetic acid and / or its salt (F) in terms of acetate ions is 0.01 to 1000 ppm based on the total of the resin composition, it is more excellent in mechanical strength, color tone stability, and moldability (stripe prevention).

[0025] In addition, the method for producing a resin composition by melt-kneading and pelletizing the above resin composition is a production method that is more excellent in moldability (stripe prevention).

[0026] In addition, the molded article obtained using the above resin composition is an excellent molded article having excellent mechanical strength and improved color tone reduction and moldability (stripe) during melt molding.

[0027] In addition, the multilayer structure having at least one layer composed of the above resin composition is an excellent multilayer structure having excellent mechanical strength and improved color tone reduction and moldability (stripe) during melt molding.

[0028] Furthermore, since the package of the present invention is composed of the above multilayer structure, the obtained package is also excellent in mechanical strength and also excellent in color tone stability and moldability (stripe).

Mode for Carrying Out the Invention

[0029] Hereinafter, the present invention will be described in detail, but these show an example of a desirable embodiment. In the present invention, "y and / or z (y and z are arbitrary configurations or components)" means three combinations: only y, only z, and y and z.

[0030] The resin composition of the present invention contains a thermoplastic resin (A) that does not contain a polar group [hereinafter, may be simply referred to as "thermoplastic resin (A)"], a thermoplastic resin (B) that contains a polar group [hereinafter, may be simply referred to as "thermoplastic resin (B)"], EVOH (C), an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) that is a metal salt of the above aliphatic carboxylic acid (D). Hereinafter, each constituent component will be described.

[0031] <Thermoplastic resin (A)> The thermoplastic resin (A) that does not contain a polar group used in the present invention is, for example, a thermoplastic resin that does not contain a polar group such as a hydroxyl group, a carboxy group, an amino group, or an amide group, and its type is not particularly limited. Examples of the above-mentioned thermoplastic resin (A) include polyolefin resins, polystyrene resins, fluorine-based resins, etc. These may be used alone or in combination of two or more.

[0032] Examples of the above-mentioned 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), high-density polyethylene (HDPE), etc., polypropylene (PP), ethylene-propylene (block or random) copolymer, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene, polymethylpentene and other olefin homopolymers or copolymers, polycyclic olefins, or blends thereof. These are used alone or in combination of two or more. Among them, polyethylene (PE), ethylene-propylene (block or random) copolymer, polypropylene (PP) and blends thereof are preferable in terms of economy and mechanical properties. Furthermore, polyethylene (PE), polypropylene (PP) and ethylene-propylene (block or random) copolymer are particularly preferable because they can further prevent the discoloration of the reground layer and the effects of the present invention are particularly excellent.

[0033] In addition, the ethylene or α-olefin of the above-mentioned polyolefin resin may be plant-derived ethylene or α-olefin derived from bioethanol, or non-plant-derived, i.e., petroleum-derived ethylene or α-olefin, and these may be used in combination of two. Since a wide variety of petroleum-derived α-olefins are available, the physical properties of the polyolefin resin can be easily adjusted by using them for production. By using plant-derived ethylene and α-olefin, the biomass content of the final product can be further increased and the environmental load can be reduced.

[0034] As a method for producing the above-mentioned plant-derived ethylene and α-olefins, according to a conventional method, a sugar solution or starch obtained from plants such as sugarcane, corn, and sweet potato is fermented by microorganisms such as yeast to produce bioethanol, which is then heated in the presence of a catalyst, and plant-derived ethylene and α-olefins (1-butene, 1-hexene, etc.) can be obtained by an intramolecular dehydration reaction or the like. Further, using the obtained plant-derived ethylene and α-olefins, a plant-derived polyethylene-based resin can be produced in the same manner as the production of a petroleum-derived polyethylene-based resin.

[0035] Regarding the methods for producing the above-mentioned plant-derived ethylene, α-olefins, and plant-derived polyethylene-based resins, they are described in detail, for example, in Japanese Patent Publication No. 2011-506628. Examples of the plant-derived polyethylene-based resin preferably used in the present invention include Green PE manufactured by Braskem S.A.

[0036] Further, the above polyolefin-based resin is produced using a Ziegler-type catalyst, and a polyolefin-based resin containing chlorine derived from the above catalyst in an amount of 0.01 to 500 ppm, preferably 0.1 to 400 ppm, more preferably 1 to 300 ppm, and particularly preferably 5 to 150 ppm is preferred. By using such a polyolefin-based resin, the effects of the present invention can be obtained more significantly.

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

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

[0039] Examples of the diene-based rubbery polymer include polybutadiene, styrene-butadiene copolymer, ethylene-propylene-non-conjugated diene terpolymer, and the like.

[0040] Further, as the polystyrene resin, a polystyrene resin containing 50% by mass or more of styrene is preferable, and among them, polystyrene is more preferable from the viewpoint of economy.

[0041] Among the above-mentioned thermoplastic resins (A), from the viewpoints of excellent recyclability and economy, it is preferably at least one selected from polyolefin resins and polystyrene resins, more preferably at least one selected from polyethylene, polypropylene, and polystyrene, and particularly preferably polypropylene.

[0042] The melt flow rate (MFR) (230 °C, load 2160 g) of the above-mentioned thermoplastic resin (A) is usually 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, and more preferably about that amount.

[0043] The content of the above-mentioned thermoplastic resin (A) is 66 to 99% by weight based on the total of the resin composition. Preferably it is 70 to 98% by weight, and more preferably 80 to 95% by weight. If the content of such thermoplastic resin (A) is too small, the mechanical strength and the color tone stability of the molded product will be insufficient, and if the content is too large, the gas barrier property and heat resistance rigidity of the laminated structure will be insufficient.

[0044] <Thermoplastic resin (B)> The thermoplastic resin (B) containing a polar group used in the present invention is not particularly limited as long as it is a resin other than the EVOH (C) described later. For example, a modified thermoplastic resin containing a carboxyl group or an acid anhydride group (for example, a modified polyolefin resin, a modified polystyrene resin, etc.) obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to the above thermoplastic resin (A) by an addition reaction, a graft reaction, etc., a polyvinyl acetate resin, a polyvinyl alcohol resin, an ionomer resin modified with metal ions, a polyamide resin, a polyester resin, a polyurethane resin, a polycarbonate resin, an acrylic resin, etc. may be mentioned. These may be used alone or in combination of two or more. Among them, from the viewpoints of excellent mechanical strength, recyclability, and economy, it is preferably a modified thermoplastic resin containing a carboxyl group or an acid anhydride group. Further, from the viewpoints of excellent mechanical strength, recyclability, and economy, it is preferably at least one selected from a polyolefin resin containing a carboxyl group or an acid anhydride group and a polyvinyl acetate resin, and more preferably a combination of a polyolefin resin containing a carboxyl group or an acid anhydride group and a polyvinyl acetate resin.

[0045] As the thermoplastic resin (A) used for the modified thermoplastic resin containing the above carboxyl group or acid anhydride group, the polyolefin resin or polystyrene resin described in the above thermoplastic resin (A) is preferably used.

[0046] In addition, examples of the unsaturated carboxylic acid used for the modified thermoplastic resin containing the above carboxyl group or acid anhydride group include unsaturated dicarboxylic acids and unsaturated monocarboxylic acids. Examples of the above unsaturated dicarboxylic acids include maleic acid, fumaric acid, chloromaleic acid, hymic acid, citraconic acid, itaconic acid, etc., and examples of the above unsaturated monocarboxylic acids include acrylic acid, butanoic acid, crotonic acid, vinylacetic acid, methacrylic acid, pentenoic acid, dodecenoic acid, linoleic acid, angelic acid, cinnamic acid, etc. Examples of the unsaturated carboxylic anhydride include acid anhydrides of the aforementioned unsaturated dicarboxylic acids or unsaturated monocarboxylic acids. Specifically, examples include maleic anhydride, hymic anhydride, itaconic anhydride, citraconic anhydride, acrylic anhydride, and the like. Two or more of the above-mentioned unsaturated carboxylic acids or unsaturated carboxylic anhydrides may be used in combination. Among these, maleic anhydride is particularly preferred because the effects of the invention can be obtained more effectively, and it is also suitable from the viewpoints of recyclability and economy.

[0047] The acid value of such a modified thermoplastic resin is usually 0.01 to 120 mgKOH / g, preferably 0.5 to 10 mgKOH / g, more preferably 0.5 to 7 mgKOH / g, still 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, and the mechanical strength of the resulting molded product tends to decrease. On the other hand, if the acid value of the modified thermoplastic resin is too high, the fluidity of the resin composition deteriorates, and the layer thickness of the resulting molded product tends to become non-uniform. When the modified thermoplastic resin is a mixture of multiple types of resins, the acid value of the acid-modified thermoplastic resin is the weighted average value of the acid values of the respective resins based on the mixing mass ratio.

[0048] As the polyvinyl acetate resin, for example, those having a vinyl acetate content measured by JIS K6924-1 of 0.01 to 60% by weight based on all monomer components can be used. Further, since the effects of the invention are easily obtained, it is preferably 0.02 to 50% by weight, and particularly preferably 0.03 to 30% by weight.

[0049] In addition, as other monomer components in addition to vinyl acetate, the polyvinyl acetate resin may contain 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 anhydride group-containing monomers such as maleic anhydride; (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters having 1 to 18 carbon atoms in the alkyl group; hydroxyl group-containing copolymerizable monomers such as (meth)acrylic acid hydroxyethyl and (meth)acrylic acid hydroxypropyl; epoxy group-containing copolymerizable monomers such as (meth)acrylic acid glycidyl; amino group-containing copolymerizable monomers such as N,N-dimethylaminoethyl (meth)acrylic acid alkyl ester; 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 can be used alone or in combination of two or more. Among these, in particular, ethylene-vinyl acetate copolymers are suitable from the viewpoint that the effects of the invention can be more easily obtained effectively.

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

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

[0052] The above polyvinyl acetate resin may be a modified product containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride by an addition reaction, a graft reaction, or the like, as long as the gist of the present invention is not inhibited. Such a modification amount is preferably, for example, 10 mol% or less.

[0053] Examples of the unsaturated carboxylic acid or its anhydride 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, maleic anhydride, and their anhydrides and half esters. Among them, maleic anhydride is preferably used from the viewpoint that the effects of the invention can be more easily obtained effectively.

[0054] The above polyvinyl acetate resin can be used alone or in combination of two or more having different vinyl acetate contents, saponification degrees, molecular weights, MFRs, densities, modified groups, and modification amounts thereof.

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

[0056] Examples of the above 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 can be used alone or in combination of two or more, but practically, vinyl acetate is preferable.

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

[0058] Examples of the monomer copolymerizable with the vinyl ester compound 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 salts or mono- or dialkyl esters thereof; 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 salts thereof; alkyl vinyl ethers; polyoxyalkylene (meth)allyl ethers such as polyoxyethylene (meth)allyl ether and polyoxypropylene (meth)allyl ether; polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)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; diacrylacetoneamide; 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 is obtained by saponifying a vinyl ester polymer obtained by polymerizing the above vinyl ester compound or the like. The saponification of the above vinyl ester polymer is carried out by dissolving the above vinyl ester polymer in an alcohol (such as methanol, ethanol, butanol, etc.) in the presence of an alkali catalyst (such as hydroxides or alcoholates of alkali metals such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate, etc.). 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 by mixing two or more kinds of PVOH having different degrees of saponification as required.

[0060] The ionomer resin modified with the metal ion is a known resin and is a thermoplastic resin having an ionic group in the side chain with respect to a hydrophobic polymer main chain. Examples of such an ionomer resin include a sulfonic acid-based ionomer having a structure in which part or all of the sulfonic acid groups of a sulfonic acid group-containing polymer are neutralized with metal ions, and a carboxylic acid-based ionomer having a structure in which part or all of the carboxy groups of an ethylene-unsaturated carboxylic acid copolymer are neutralized with metal ions.

[0061] As the metal ions that neutralize the acid moieties such as sulfonic acid groups and carboxy groups of the ionomer resin, usually, monovalent metal ions such as lithium, sodium, potassium, rubidium, cesium, etc., divalent metal ions such as calcium, magnesium, iron, zinc, etc., trivalent metal ions such as iron, aluminum, etc. are mentioned. The metal cation content in the ionomer is usually desirably in the range of 0.4 to 4 mol, preferably 0.6 to 2 mol per 1 kg of the ionomer. Also, as the degree of neutralization, those in which 15 to 80%, preferably 20 to 60% of the acid amount in the copolymer component is neutralized with the above metal cations are preferably used. Among them, a divalent metal ion neutralized product is preferable from the viewpoint of affinity with EVOH(C), and a zinc ion neutralized product is particularly preferable.

[0062] Specific examples of the sulfonic acid-based ionomer include, for example, polystyrene sulfonate (PSS) ionomer, ethylene-based sulfonate ionomer, and the like. Specific examples of the carboxylic acid-based ionomer include, for example, ionomers such as carboxylate ionomers like ethylene-unsaturated carboxylic acid copolymers. Among them, from the viewpoint of affinity with EVOH(C), it is preferable to use a carboxylic acid-based ionomer, and particularly preferably an ionomer of an ethylene-unsaturated carboxylic acid copolymer.

[0063] Examples of the unsaturated carboxylic acid in the ionomer of the ethylene-unsaturated carboxylic acid copolymer include, for example, (meth)acrylic acid, maleic acid, fumaric acid, maleic anhydride, monomethyl maleate, monoethyl maleate, and the like. These can be used alone or in combination of a plurality at the same time. Among them, (meth)acrylic acid is particularly preferable.

[0064] In addition, the ionomer of the ethylene-unsaturated carboxylic acid copolymer may contain a small amount (for example, less than 20% by weight) of other monomers that can be copolymerization components. Examples of the other monomers 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, as the ionomer resin, a divalent metal ion neutralization product of an ethylene-(meth)acrylic acid copolymer is preferable, and particularly preferably a zinc ion neutralization product of an ethylene-(meth)acrylic acid copolymer.

[0066] As the polyamide-based resin, known homopolyamide-based resins and copolymer polyamide-based resins can be used. Examples of the above-mentioned homopolyamide-based resins include polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecanamide (nylon 11), polylauryl lactam (nylon 12), and the like. Examples of the copolyamide resin include aliphatic polyamides such as 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), 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), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 66 / 610), 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, poly-p-phenylene·3,4'-diphenyl ether terephthalamide; amorphous polyamides; those obtained by modifying these polyamide resins with aromatic amines such as methylene benzylamine and metaxylylenediamine; and metaxylylenediammonium adipate. Further, the polyamide resin may be a terminal-modified polyamide resin obtained by modifying the terminals of the above homopolyamide resin or copolyamide resin. These may be used alone or in combination of two or more. Among them, terminal-modified polyamide resins are preferred.

[0067] Examples of the polyester resin include polymers or copolymers obtained by a condensation reaction mainly composed of a dicarboxylic acid and a diol or their ester derivatives.

[0068] As the dicarboxylic acid, an aromatic dicarboxylic acid is preferable. For example, terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-biphenyl ether dicarboxylic acid, 4,4'-biphenylmethane dicarboxylic acid, 4,4'-biphenylsulfone dicarboxylic acid, 4,4'-biphenylisopropylidene dicarboxylic 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. may be mentioned. These dicarboxylic acids may be used as a mixture of two or more kinds.

[0069] If the amount is small, one or more aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid can be mixed and used together with the above aromatic dicarboxylic acid.

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

[0071] Specific polyester resins include, for example, 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, etc. In addition, copolymer polyesters such as polyethylene isophthalate / terephthalate and polybutylene terephthalate / isophthalate can be mentioned. Among these, PET, PBT, PBN, and PEN with a balanced mechanical property, etc., can be 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] The reason why excellent effects are obtained by using the thermoplastic resin (B) is not clear, but it is presumed that by using the thermoplastic resin (B), the dispersion size of EVOH (C) present in the resin composition is refined, so that the resin composition is likely to absorb energy when receiving external deformation, and as a result, the mechanical strength is improved.

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

[0075] From the viewpoints of excellent mechanical strength, recyclability, and economy, the content of the above-mentioned thermoplastic resin (B) is preferably 0.1 to 50% by weight, more preferably 0.3 to 25% by weight, still more preferably 0.5 to 15% by weight, and particularly preferably 1.0 to 10% by weight based on the total of the resin composition. If the content of such a thermoplastic resin (B) is too small, the dispersibility of EVOH (C) decreases, and the mechanical strength of the molded article tends to be insufficient. If the content is too large, the affinity with EVOH (C) becomes too high, and high-polymerized products are likely to be generated, resulting in insufficient moldability as a resin composition or insufficient mechanical strength of the molded article.

[0076] <EVOH(C)> The EVOH (C) used in the present invention is usually a resin obtained by saponifying an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene and 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 can be used, such as solution polymerization, suspension polymerization, and emulsion polymerization. Generally, solution polymerization using methanol as a solvent is used. The saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.

[0077] That is, the EVOH (C) used in the present invention mainly consists of ethylene structural units and vinyl alcohol structural units, and contains a small amount of vinyl ester structural units remaining without saponification.

[0078] As the above vinyl ester monomer, vinyl acetate is typically used from the viewpoints of easy availability from the market and good efficiency in treating impurities during production. In addition, examples of the vinyl ester monomer include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprinate, vinyl laurate, vinyl stearate, vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. Among them, aliphatic vinyl esters having 3 to 20 carbon atoms, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms are preferred. These are usually used alone, but a plurality of them may be used simultaneously as necessary.

[0079] In addition to the ethylene structural unit and the vinyl alcohol structural unit (including the unsaponified vinyl ester structural unit), the above EVOH (C) may further contain structural units derived from the following comonomers. Examples of the comonomer include α-olefins such as propylene, isobutene, α-octene, α-dodecene, and α-octadecene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, and 3-butene-1,2-diol, and hydroxy group-containing α-olefin derivatives such as their esters and acylates; hydroxymethylvinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy-2-methylenepropane; unsaturated carboxylic acids or their salts, partial alkyl esters, complete alkyl esters, nitriles, amides or anhydrides; unsaturated sulfonic acids or their salts; vinyl silane compounds; vinyl chloride; styrene, etc.

[0080] Furthermore, as the above EVOH(C), "post-modified" EVOH such as urethanized, acetalized, cyanoethylated, oxyalkylenated EVOH can also be used.

[0081] Among the above-modified EVOHs, EVOH in which primary hydroxyl groups are introduced into the side chain by copolymerization is preferable in that the secondary formability such as stretching treatment and vacuum / pressure air forming becomes good. In particular, EVOH having a 1,2-diol structure in the side chain is preferable.

[0082] The content of the ethylene structural unit in the above EVOH(C) is a value measured based on ISO14663 and is 20 to 60 mol%, preferably 25 to 50 mol%, particularly preferably 25 to 35 mol%. If such content is too low, the gas barrier property and melt formability at high humidity will decrease. Conversely, if it is too high, the gas barrier property will decrease.

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

[0084] Also, the melt flow rate (MFR) (210 °C, load 2160 g) of the above EVOH(C) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, particularly preferably 3 to 35 g / 10 min. If such MFR is too high, the film-forming property tends to decrease. Also, if MFR is too low, melt extrusion tends to be difficult.

[0085] In addition, the EVOH (C) used in the present invention may be a mixture with other different EVOHs. Examples of such other EVOHs include those with different ethylene contents, different saponification degrees, different melt flow rates (MFRs), different other copolymer components, different modification amounts (for example, those with different contents of structural units containing primary hydroxyl groups in the side chain), and the like.

[0086] The content of the above 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 of the resin composition. If the content of such EVOH (C) is too small, the gas barrier property of the molded product will be insufficient, and if the content is too large, the mechanical strength of the molded product will be insufficient.

[0087] <Aliphatic carboxylic acid (D) having 3 or more carbon atoms> The resin composition of the present invention contains an aliphatic carboxylic acid other than acetic acid, that is, an aliphatic carboxylic acid (D) having 3 or more carbon atoms (hereinafter, may be referred to as "aliphatic carboxylic acid (D)"). The number of carbon atoms of the above aliphatic carboxylic acid (D) is usually 3 to 30, preferably 4 to 20, and particularly preferably 5 to 14. When the number of carbon atoms of the above aliphatic carboxylic acid (D) is within the above range, it is preferable from the viewpoint of economy.

[0088] Examples of the above aliphatic carboxylic acid (D) include aliphatic monocarboxylic acids having 1 carboxy group, aliphatic dicarboxylic acids having 2 carboxy groups, aliphatic tricarboxylic acids having 3 carboxy groups, and the like. Examples of the aliphatic monocarboxylic acid include saturated aliphatic monocarboxylic acids such as 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, mevalonic acid, pantothenic acid, etc., 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, ricinoleic acid, etc. Examples of the aliphatic dicarboxylic acid include saturated aliphatic dicarboxylic acids such as succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc., and unsaturated aliphatic dicarboxylic acids such as eicosadienoic acid, docosadienoic acid, etc. Examples of the aliphatic tricarboxylic acid include saturated aliphatic tricarboxylic acids such as citric acid, isocitric acid, aconitic acid, etc. These aliphatic carboxylic acids (D) can be used alone or in combination of two or more. Among them, from the viewpoint of thermal stability (prevention of viscosity increase and fish-eye generation during melt molding), an aliphatic monocarboxylic acid having one carboxy group is preferable, a saturated aliphatic monocarboxylic acid is more preferable, and stearic acid, caproic acid, caprylic acid, lauric acid, and behenic acid are particularly preferable.

[0089] The content of the aliphatic carboxylic acid (D) in terms of carboxylic acid ions is usually 0.0001 to 150 ppm, preferably 0.001 to 100 ppm, particularly preferably 0.005 to 75 ppm, and especially preferably 0.01 to 50 ppm with respect to the total of the resin composition from the viewpoint of excellent color tone stability. If the content is too small, the thermal stability of the aliphatic carboxylic acid metal salt (E) described below will be insufficient, and as a result, the effects of the invention tend not to be fully obtained. If the content is too large, the color tone stability during melt molding tends to decrease, or the aliphatic carboxylic acid (D) itself acts as a plasticizer, and the effects of the invention tend not to be fully obtained. The content of the aliphatic carboxylic acid (D) in terms of carboxylic acid ions can be determined by the method described below.

[0090] <aliphatic carboxylic acid metal salt (E)> The resin composition of the present invention contains an aliphatic carboxylic acid metal salt (E) which is a metal salt of the above aliphatic carboxylic acid (D).

[0091] As the metal species of the above aliphatic carboxylic acid metal salt (E), it is essential that it is an element belonging to the 4th period d-block in the long-period type periodic table. Among them, chromium, cobalt, nickel, copper, and zinc are preferable, and particularly preferably, zinc which can obtain particularly excellent effects and is inexpensive and easily available.

[0092] The reason why excellent effects are obtained by using the above aliphatic carboxylic acid metal salt (E) is not clear, but since the metal species of the above aliphatic carboxylic acid metal salt (E) is at least one selected from elements belonging to the 4th period d-block of the long-period type periodic table, excessive thermal decomposition of EVOH (C) that causes a decrease in mechanical properties is moderately suppressed, and the interaction between the thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) in the resin composition is enhanced. As a result, the high-order structures such as molecular orientation and crystal structure formed when the resin composition is extrusion-molded are highly homogenized, and it is presumed that the mechanical strength is improved as a result.

[0093] As the anionic species of the above aliphatic carboxylic acid metal salt (E), those exemplified as the above aliphatic carboxylic acid (D) can be used. However, in the present invention, it is important that the anionic species of the above aliphatic carboxylic acid metal salt (E) and the anionic species of the above aliphatic carboxylic acid (D) are the same species. By the anionic species of the above aliphatic carboxylic acid metal salt (E) and the above aliphatic carboxylic acid (E) being the same species, a resin composition excellent in mechanical strength and having higher color tone stability even when melt-molded can be obtained. In the case where the resin composition of the present invention contains a plurality of the above aliphatic carboxylic acids (D) or a plurality of the above aliphatic carboxylic acid metal salts (E), it is sufficient that the anionic species of at least one of the above aliphatic carboxylic acids (D) and the above aliphatic carboxylic acid metal salt (E) are the same species.

[0094] The reason why excellent effects are obtained by the anionic species of the above aliphatic carboxylic acid (D) and the above aliphatic carboxylic acid metal salt (E) being the same species is not clear. However, it is presumed that by using the aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) whose anionic species are the same as those of the aliphatic carboxylic acid (D) in combination, the dispersibility of the above aliphatic carboxylic acid metal salt (E) is remarkably improved, and more excellent effects of the invention can be obtained. Further, the above aliphatic carboxylic acid (D) is considered to interact with the metal species of the above aliphatic carboxylic acid metal salt (E) and exist in a state like a metal complex. By the anionic species of such an aliphatic carboxylic acid metal salt (E) being the same as those of the aliphatic carboxylic acid (D), it becomes possible to exist in a more energetically stable state, and it is presumed that the heat stability is excellent even when melt-molded, and as a result, the mechanical properties and color tone stability of the resin composition are improved.

[0095] The content of the aliphatic carboxylic acid metal salt (E) 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 most preferably 0.1 to 50 ppm, based on the total amount of the resin composition, from the viewpoints of excellent mechanical strength, color tone stability, and moldability (prevention of surface gloss). If the content of the aliphatic carboxylic acid metal salt (E) is too small, the effects of the invention tend not to be fully obtained. If the content is too large, the color tone stability during melt molding tends to decrease.

[0096] The content of the aliphatic carboxylic acid metal salt (E) in terms of metal ions and the content of the aliphatic carboxylic acid (D) in terms of carboxylic acid ions are not particularly limited and can be measured by known analytical methods. For example, they can be determined by the following methods alone or in combination. [Content of the aliphatic carboxylic acid metal salt (E) in terms of metal ions] Precisely weigh a dried sample, place it in a platinum evaporation dish that has been made constant in weight, carbonize it with an electric heater, then heat it with a gas burner until no more smoke is emitted, and further place the platinum evaporation dish in an electric furnace, raise the temperature to completely ash it. After cooling this, add hydrochloric acid and pure water to the ash, heat and dissolve it with an electric heater, pour it into a volumetric flask, make the volume constant with pure water to obtain a sample for atomic absorption analysis. By quantitatively analyzing the amount of metal in this sample for atomic absorption analysis by atomic absorption spectrometry, the content of the aliphatic carboxylic acid metal salt (E) in terms of metal ions can be determined. [Content of the aliphatic carboxylic acid (D) other than acetic acid in terms of carboxylic acid ions] Using liquid chromatography-mass spectrometry (LC / MS), gas chromatography-mass spectrometry (GC / MS), etc., quantify the total content (d x ) of the aliphatic carboxylic acid (D) and its metal salt (E) in terms of carboxylic acid ions in the resin composition. Then, from the content of the aliphatic carboxylic acid metal salt (E) in terms of metal ions described above, the content of the aliphatic carboxylic acid metal salt (E) in terms of carboxylic acid ions (d y) is calculated. The total content of the aliphatic carboxylic acid (D) and its metal salt (E) converted into carboxylate ion (d x ) and the content of aliphatic carboxylate metal salt (E) converted to carboxylate ion (d y ) difference ((d x )―(d y )) to calculate the content of aliphatic carboxylic acid (D) calculated as carboxylate ion.

[0097] In addition, in the resin composition of the present invention, the ratio of the content of the aliphatic carboxylic acid metal salt (E) in terms of metal ions to the content of the aliphatic carboxylic acid (D) in terms of carboxylate ions ((E) content in terms of metal ions / (D) content in terms of carboxylate ions) is preferably, on a weight basis, usually 0.11≦((E) / (D))≦100, more preferably 0.13≦((E) / (D))≦90, particularly preferably 0.15≦((E) / (D))≦80, and particularly preferably 0.2≦((E) / (D))≦70. When such a value is within the above range, the effects of the present invention tend to be more pronounced, and when it is smaller than the above range, the color stability during melt molding tends to be insufficient or the effects of the present invention tend not to be sufficiently obtained, and when it is larger than the above range, the color stability during melt molding tends to be insufficient or the moldability tends to be insufficient.

[0098] The reason why excellent effects are obtained by setting the content ratio ((E) / (D)) of the aliphatic carboxylic acid (D) to the aliphatic carboxylic acid metal salt (E) within the above range is not clear, but by using the aliphatic carboxylic acid (C) and the aliphatic carboxylic acid metal salt (E) whose anion species is the same as that of the aliphatic carboxylic acid (C) in a specific ratio, there is an effect of improving the dispersibility and thermal stability of the aliphatic carboxylic acid metal salt (E). On the other hand, if the content of the aliphatic carboxylic acid (D) is too high, the aliphatic carboxylic acid (D) itself acts as a plasticizer, and it is presumed that the effect of the present invention (mechanical strength improvement effect) cannot be sufficiently obtained.

[0099] <Acetic acid and / or its salts (F)> The resin composition of the present invention preferably contains acetic acid and / or its salt (F).

[0100] Specific examples of the acetic acid and / or its salt (F) 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 them, acetic acid, sodium acetate, potassium acetate, calcium acetate, and magnesium acetate are preferred, acetic acid, sodium acetate, and potassium acetate are particularly preferred, and acetic acid and sodium acetate are even more preferred.

[0101] The content of the acetic acid and / or its salt (F) in terms of acetic acid 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, based on the total amount of the resin composition. 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 (E). If the content is too high, the color tone stability during melt molding tends to decrease, or the effects of the invention tend not to be fully obtained.

[0102] The content of the acetic acid and / or its salt (F) in terms of acetic acid ions is not particularly limited and can be measured by known analytical methods. For example, it can be evaluated by using liquid chromatography-mass spectrometry (LC / MS), gas chromatography-mass spectrometry (GC / MS), etc.

[0103] In the resin composition of the present invention, the ratio of the metal ion content of the aliphatic carboxylate (E) to the acetate ion content of the acetic acid and / or its salt (F) ((E) content in terms of metal ions / (F) content in terms of acetate ions) is, on a weight basis, usually 0.001≦((E) / (F))≦1.3, preferably 0.005≦((E) / (F))≦1.1, particularly preferably 0.005≦((E) / (F))≦1.0, and particularly preferably 0.01≦((E) / (F))≦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 obtained, and when it is above the above range, the color stability during melt molding and the adhesive strength tend to be insufficient.

[0104] The reason why an excellent effect is obtained by satisfying the above content ratio ((E) / (F)) of the acetic acid and / or its salt (F) to the aliphatic carboxylate metal salt (E) is not clear, but it is presumed that, while a specific amount of acetic acid and / or its salt (F) has the effect of capturing thermal decomposition products of the aliphatic carboxylate metal salt (E) and suppressing a decrease in adhesive strength, an excessively large content of acetic acid and / or its salt (F) significantly reduces the thermal stability of EVOH (C), making it easy for color stability to decrease or preventing the effect of the present invention (effect of improving impact resistance) from being fully obtained.

[0105] [Other thermoplastic resins] The resin composition of the present invention may contain other thermoplastic resins other than the thermoplastic resin (A), the thermoplastic resin (B), and the EVOH (C) within a range that does not impair the effects of the present invention (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 the strength or impart other functions.

[0106] Examples of the above-mentioned other thermoplastic resins include halogenated polyolefins such as polyvinyl chloride, polyvinylidene chloride, acrylic resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, and chlorinated polypropylene, and aromatic or aliphatic polyketones. These may be used alone or in combination of two or more.

[0107] <Other Additives> In the resin composition of the present invention, additives generally blended in resin compositions, such as heat stabilizers, inorganic fillers, antioxidants, antistatic agents, colorants, ultraviolet absorbers, lubricants (e.g., saturated fatty acid amides such as stearic acid amide, unsaturated fatty acid amides such as oleic acid amide, bis-fatty acid amides such as ethylene bis-stearic acid amide, etc.), plasticizers (e.g., aliphatic polyhydric alcohols such as ethylene glycol, glycerin, hexanediol, 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., may be contained within a range that does not inhibit the effects of the present invention (for example, usually 30% by weight or less, preferably 10% by weight or less of the resin composition). These can be used alone or in combination of two or more.

[0108] Examples of the above-mentioned inorganic filler include hydrotalcite-based compounds, mica, talc, calcium carbonate, titanium oxide, kaolin, clay, glass flakes, glass beads, vermiculite, smectite, etc. They may be used alone or in combination of two or more.

[0109] Examples of the above-mentioned hydrotalcite-based compounds include hydrotalcite-based solid solutions represented by the following general formula (1).

[0110] [Chemical Formula 1] [(M1 2+ ) y1 (M2 2+ ) y2 1-x M x 3+ (OH)2A n- x / n ·mH2O ……(1) [where 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, and 0 ≤ m < 2, respectively.]

[0111] In the general formula (1) above, 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 can be used alone or in combination of two or more, and among them, Al is practical. Also, in the general formula (1) above, 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 - , CO3 2- , (OOCHC=CHCOO) 2- , [Fe(CN)6] 4- etc. These can be used alone or in combination of two or more, and among them, CO3 2- and OH - are useful.

[0112] And, as specific examples of the above 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 、[Mg 0.75 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 and [Mg 0.14 Ca 0.57 Zn 0.28 0.7 Al 0.30 (OH) 2.3 ·0.25H2O and others can be mentioned. Among them, [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 and [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 and others can be mentioned.

[0113] In addition, for example, compounds represented by the following general formula (2) can be mentioned.

[0114] [Chemical formula 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, z are positive numbers, and a is 0 or a positive number.]

[0115] As the compound represented by the above general formula (2), specifically, 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 Al2(OH)(CO3)2·4H2O, Mg6Al2(OH)HPO4·4H2O, Ca6Al2(OH)CO3·4H2O, Zn6Al6(OH)CO3·4H2O, etc. Further, it is not limited to the above. For example, even those with an unclear chemical formula such as a part of OH in Mg2Al(OH)9·3H2O being replaced by CO3 or HPO4, or even those with the crystal water removed (a = 0), can be expected to have the same effect. In particular, among these, compounds where M is Mg and E is CO3 are preferable from the viewpoint of recyclability.

[0116] Regarding the particle size of the above 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, when the above average particle size is too large, the effects of the present invention tend not to be fully obtained. Here, the average particle size referred to is the value measured by the LUZEX method.

[0117] Among the above hydrotalcites, it is particularly preferable to use the hydrotalcite-based solid solution represented by the general formula (1) above, from the viewpoints of high molding stability, high effect of suppressing foreign matter (eye varnish) generated by phase separation, and high coloring suppression effect.

[0118] Further, the average particle size of the above inorganic filler other than the hydrotalcite-based compound is preferably usually 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, gels due to aggregation of the particles will be generated in the molded product, and the heat-resistant rigidity of the laminated structure will also be insufficient. Also, if it exceeds 20 μm, it will be difficult to suppress the increase in resin pressure.

[0119] Also, the content of the above inorganic filler is preferably usually 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 of the resin composition.

[0120] Examples of the antioxidant include hindered phenol compounds: dibutylhydroxytoluene, 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis-(6-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), tetrakis-[methylen-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, N,N'-hexamethylenebis(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-butylanilino)-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-hydroxybenzylphosphonic acid 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, etc., monoalkyldiphenyl phosphites such as diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, and alkyarylphenyl phosphites such as diarylmonophenyl phosphite like phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, etc., trialkyl phosphites such as triisooctyl phosphite, tristearyl phosphite, etc., bis(2,4-di-t-butylphenyl)pentaerythritol-di-phosphite, etc.; thioether compounds: pentaerythritol-tetrakis-(β-laurylthiopropionate), tetrakis[methylene-3-(dodecylthio)propionate]methane, bis[2-methyl-4-{3-n-alkylthiopropionyloxy}-5-t-butylphenyl]sulfide, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, pentaerythrityl-tetrakis(3-laurylthiopropionate), ditridecyl-3,3'-thiodipropionate, 2-mercaptobenzimidazole, etc.; hindered amine compounds: dimethyl succinate·1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine 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-4piperidyl)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, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butyl malonic acid bis(1,2,2,6,6-pentamethyl-4-piperidyl), 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, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, methyl-3-[3-t-butyl-5-(2H-benzotriazole-2-yl)-4-hydroxyphenyl]propionate-polyethylene glycol condensate, hydroxyphenylbenzotriazole derivatives, 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole, etc.; benzophenone compounds: 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, etc.; and the like, and at least one or more thereof can be selected from these. As the properties of this antioxidant, any form such as powdery, granular, liquid, paste, emulsion, etc. can be used.,

[0121] Among them, hindered phenol-based antioxidants are preferred. 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 in terms of excellent effect of reducing the thermal degradation of the resin composition of the present invention.,

[0122] The content of the above 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 of the resin composition.

[0123] Specific examples of the phosphoric acid and / or its salts include, for example, phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, calcium hydrogen 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 them, preferably phosphoric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium dihydrogen phosphate, zinc hydrogen phosphate, and particularly preferably phosphoric acid, sodium dihydrogen phosphate, calcium dihydrogen phosphate, magnesium dihydrogen phosphate, and especially preferably phosphoric acid.

[0124] The content of the above phosphoric acid and / or its salts is preferably usually 0.001 to 300 ppm or less, more preferably 0.005 to 200 ppm, and even more preferably 0.01 to 100 ppm based on the total of the resin composition.

[0125] Specific examples of the cinnamic acid and / or its salts include, for example, cis-cinnamic acid, trans-cinnamic acid. From the viewpoints of stability and price, trans-cinnamic acid is preferably used. Also, examples of cinnamate salts include alkali metal cinnamate salts such as lithium cinnamate, sodium cinnamate, potassium cinnamate, etc., and alkaline earth metal cinnamate salts such as magnesium cinnamate, calcium cinnamate, barium cinnamate, etc. These cinnamic acids and / or their salts can be used alone or in combination of two or more. Among them, it is preferable to use trans-cinnamic acid alone.

[0126] The content of the above 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 still more preferably 1.5 to 50 ppm based on the total amount of the resin composition.

[0127] The conjugated polyene compound is a compound having a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately connected, and having two or more carbon-carbon double bonds, that is, a compound having a so-called conjugated double bond. The conjugated polyene compound may be a conjugated diene having a structure in which two carbon-carbon double bonds and one carbon-carbon single bond are alternately connected, a conjugated triene having a structure in which three carbon-carbon double bonds and two carbon-carbon single bonds are alternately connected, or a conjugated polyene compound having a structure in which a larger number of carbon-carbon double bonds and carbon-carbon single bonds are alternately connected. However, when the number of conjugated carbon-carbon double bonds is 8 or more, there is a concern that the molded article may be colored due to the color of the conjugated polyene compound itself. Therefore, it is preferably a polyene having 7 or less conjugated carbon-carbon double bonds. Also, a plurality of the above conjugated double bonds composed of two or more carbon-carbon double bonds may be present in one molecule without being conjugated to each other. For example, a compound having three conjugated trienes in the same molecule, such as tung oil, is also included in the conjugated polyene compound.

[0128] Specific examples of the conjugated polyene compound include conjugated diene compounds having two carbon-carbon double bonds such as isoprene, myrcene, farnesene, sembrene, sorbic acid, sorbic acid ester, sorbate, 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; 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.

[0129] The content of the conjugated polyene compound is preferably usually 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.

[0130] <Method for producing resin composition> The method for producing the resin composition of the present invention is not particularly limited, and examples thereof include the methods shown in the following (I) to (IV). Note that the methods shown in the following (I) to (IV) may be used in combination. (I) A method of dry blending (dry blending method) by blending at least one of a thermoplastic resin (B), EVOH (C), an aliphatic carboxylic acid (D), and an aliphatic carboxylic acid metal salt (E) with pellets of a thermoplastic resin (A) in a predetermined ratio. (II) A method of dipping (dipping method) by dipping pellets of at least one of a thermoplastic resin (A), a thermoplastic resin (B), and EVOH (C) into a solution containing at least one of an aliphatic carboxylic acid (D) and an aliphatic carboxylic acid metal salt (E), and then drying the pellets. (III) A method of melt-kneading (melt-kneading method) by blending at least one of a thermoplastic resin (A), a thermoplastic resin (B), EVOH (C), an aliphatic carboxylic acid (D), and an aliphatic carboxylic acid metal salt (E) in a predetermined ratio, and then producing pellets. (IV) A method of solution mixing by adding and mixing at least one of an aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) to a solution containing pellets of at least one of a thermoplastic resin (A), a thermoplastic resin (B), and EVOH (C), and then removing the solvent in the solution.

[0131] Among these, the method of melt-kneading (melt-kneading method) by blending at least one of a thermoplastic resin (A), a thermoplastic resin (B), EVOH (C), an aliphatic carboxylic acid (D), and an aliphatic carboxylic acid metal salt (E) in a predetermined ratio, and then producing pellets is practical and industrially preferable in terms of productivity and economy. Also, when blending the other thermoplastic resins and additives, a resin composition containing the other thermoplastic resins and additives can be obtained by following the methods of (I) to (IV) above.

[0132] As the means for dry blending in the method of (I) above, for example, known mixing devices such as a locking mixer, a ribbon blender, a line mixer, etc. can be used.

[0133] In the dry blending in the method of (I) above, in order to improve the adhesiveness of at least one component of the aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E), it is preferable to adjust the moisture content of at least one kind of pellet of the thermoplastic resin (A), the thermoplastic resin (B), and EVOH (C) to 0.1 to 5% by weight (more preferably 0.5 to 4% by weight, particularly 1 to 3% by weight). When such a moisture content is too small, at least one of the aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) tends to easily fall off and the adhesion distribution tends to be non-uniform. Conversely, when it is too large, at least one of the aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) tends to aggregate and the adhesion distribution tends to be non-uniform.

[0134] Note that the moisture content of at least one kind of pellet of the thermoplastic resin (A), the thermoplastic resin (B), and EVOH (C) is measured and calculated by the following method. [Method for Measuring Moisture Content] Weigh at least one kind of pellet of the thermoplastic resin (A), the thermoplastic resin (B), and EVOH (C) with an electronic balance (W1: unit g), then put it into a hot air oven type dryer maintained at 150 °C, dry it for 5 hours, and then weigh the weight after further cooling in a desiccator for 30 minutes in the same way (W2: unit g), and calculate from the following formula. [Formula] Moisture content (%) = {(W1 - W2) / W1} × 100

[0135] In the methods of (I) and (II) above, pellets with at least one component of the aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) attached to the outside of at least one kind of pellet of the thermoplastic resin (A), the thermoplastic resin (B), and EVOH (C) can be obtained.

[0136] As the means for melt-kneading in the method of (III) above, for example, known melt-kneading apparatuses such as a kneader, a ruder, an extruder, a mixing roll, a Banbury mixer, a plast mill, etc. can be used, and it is usually carried out at 150 to 300 °C (more preferably 180 to 280 °C) for about 1 to 20 minutes of melt-kneading. In particular, using a single-screw or twin-screw extruder is industrially advantageous in that pellets can be easily obtained, and it is also preferable to provide a vent suction device, a gear pump device, a screen device, etc. as necessary. In particular, in order to remove moisture and by-products (such as low molecular weight thermal decomposition products), one or more vent holes are provided in the extruder and suction is carried out under reduced pressure, or in order to prevent the mixing of oxygen into the extruder, an inert gas such as nitrogen is continuously supplied into the hopper, whereby a resin composition with excellent quality in which thermal coloring and thermal deterioration are reduced can be obtained.

[0137] Also, the supply method to a melt-kneading apparatus such as an extruder is not particularly limited, 1) A method of dry-blending the thermoplastic resin (A), the thermoplastic resin (B), the EVOH (C), the aliphatic carboxylic acid (D), and the aliphatic carboxylic acid metal salt (E) and supplying them all at once to the extruder 2) A method (solid side feed method) of supplying at least one kind of pellet of the thermoplastic resin (A), the thermoplastic resin (B), and the EVOH (C) to the extruder to melt it and then supplying the solid aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) 3) A method (melt side feed method) of supplying at least one kind of pellet of the thermoplastic resin (A), the thermoplastic resin (B), and the EVOH (C) to the extruder to melt it and then supplying the molten aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) etc. can be mentioned, and among them, the method of 1) is practical in terms of the simplicity of the apparatus, the cost of the blend, etc.

[0138] Also, from the viewpoint of reducing the environmental load, the following methods 4) to 6) using scraps containing a layer made of the thermoplastic resin (A) and a layer made of the EVOH (C) as raw materials are also preferable. 4) A method of dry-blending a scrap containing a layer made of a thermoplastic resin (A) and a layer made of EVOH (C) with a thermoplastic resin (B), an aliphatic carboxylic acid (D), and an aliphatic carboxylic acid metal salt (E), and feeding them all at once into an extruder 5) A method of dry-blending pellets obtained by melt-kneading a thermoplastic resin (B), an aliphatic carboxylic acid (D), and an aliphatic carboxylic acid metal salt (E) with a scrap containing a layer made of a thermoplastic resin (A) and a layer made of EVOH (C), and feeding them all at once into an extruder 6) A method of dry-blending a scrap containing a layer made of a thermoplastic resin (A), an aliphatic carboxylic acid (D), an aliphatic carboxylic acid metal salt (E), and a layer made of EVOH (C) with a thermoplastic resin (B), and feeding them all at once into an extruder Examples thereof include the above, but among them, the method of 4) is practical in terms of simplicity of the apparatus, cost, etc.

[0139] The above scrap is obtained by collecting the ends and defective products generated during the production of a multilayer structure or a molded body. Furthermore, it may be a multilayer structure containing a recovered material layer including the above scrap. That is, a multilayer structure and a molded body containing a recovered material layer made of a resin composition obtained from the ends and defective products generated during the production of a multilayer structure and a molded body are produced, and the scrap of the multilayer structure and the molded body is recovered and used as a raw material for the resin composition of the present invention.

[0140] The scrap is preferably pulverized to an appropriate size. Also, as the scrap, the scrap obtained from one type of multilayer structure and molded body may be used, or the scraps obtained from two or more types of multilayer structures and molded bodies may be mixed and used.

[0141] Furthermore, the above scrap may be composed of a multilayer structure and a molded body discarded by general consumers as plastic waste. That is, a multilayer structure and a molded body discarded by general consumers as plastic waste are recovered, and the scrap recovered product of the multilayer structure and the molded body may be used as a raw material for the resin composition of the present invention.

[0142] Also, as a method for producing pellets after melt-kneading, known methods can be used, such as the strand cut method, the hot cut method (air cut method, underwater cut method), etc. From the viewpoint of industrial productivity, the strand cut method is preferably used.

[0143] For the solvent used in the solution mixing method in the method of (IV) above, a known good solvent may be used. In particular, as a typical good solvent for EVOH (C), a mixed solvent of an aliphatic alcohol having 1 to 4 carbon atoms and water is used, and preferably a mixed solvent of water and methanol. Heating and pressurization can be arbitrarily performed during dissolution, and the concentration is also arbitrary. Aliphatic carboxylic acid (D) and aliphatic carboxylic acid metal salt (E) may be blended into a solution or paste in which at least one kind of pellet of thermoplastic resin (A), thermoplastic resin (B), and EVOH (C) is dissolved. At this time, the aliphatic carboxylic acid (D) and the aliphatic carboxylic acid metal salt (E) can be blended in a state such as a solid, a solution, or a dispersion. After blending, the resin composition solution or paste uniformly stirred is pelletized by the above-mentioned known method. From the viewpoint of industrial productivity, the underwater cut method is preferably used. The obtained pellets are dried by a known method.

[0144] The shape of the above pellets can adopt any shape such as spherical, oval, cylindrical, cubic, rectangular parallelepiped, etc. Usually, it is oval or cylindrical. From the viewpoint of convenience when used as a molding material later, 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 bottom surface 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.

[0145] In this way, the resin composition of the present invention can be obtained.

[0146] <Molded body> The molded article of the present invention is melt-molded from the resin composition of the present invention. The above-mentioned molded article can be used as it is for various shapes (films, sheets, cups, trays, bottles, tanks, pipes, tubes, transport pallets, chairs, desks, piles, etc.), but if necessary, a (heating) stretching treatment is performed. The stretching treatment may be either uniaxial stretching or biaxial stretching. In the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Also, as the stretching method, a method with a high stretching ratio among roll stretching method, tenter stretching method, tubular stretching method, stretch blow method, vacuum pressure forming, etc. can be adopted. 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, the stretchability tends to be poor, and if it is too high, it tends to be difficult to maintain a stable stretching state.

[0147] In addition, for the purpose of imparting dimensional stability to the above-mentioned molded article after stretching, heat setting may be performed. Heat setting can be carried out by well-known means. For example, the above-mentioned stretched multilayer structure (stretched film) is heat-treated at usually 80 to 180°C, preferably 100 to 165°C, for usually about 2 to 600 seconds while maintaining a tension state.

[0148] Also, when using the single-layer stretched film obtained using the resin composition of the present invention as a shrink film, in order to impart heat shrinkability, the above heat setting is not performed, and for example, a treatment such as blowing cold air onto the stretched film for cooling and fixing may be performed.

[0149] Furthermore, it is also possible to obtain cup- or tray-shaped single-layer containers from the molded article of the present invention. As a method for producing a single-layer container, a drawing molding method is usually employed, and specifically, a vacuum molding method, a pressure air molding method, a vacuum-pressure air molding method, a plug assist type vacuum-pressure air molding method, etc. can be mentioned. Furthermore, when obtaining a tube- or bottle-shaped single-layer container from a single-layer parison (a hollow tubular preform before blowing), a blow molding method is employed, and specifically, an extrusion blow molding method (for example, a double-headed type, a mold transfer type, a parison shift type, a rotary type, an accumulator type, a horizontal parison type, etc.), a cold parison type blow molding method, an injection blow molding method, a biaxial stretching blow molding method (for example, an extrusion type cold parison biaxial stretching blow molding method, an injection type cold parison biaxial stretching blow molding method, an injection molding in-line type biaxial stretching blow molding method, etc.) and the like can be mentioned. The molded article of the present invention can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box making, tube making, split processing, etc. as required.

[0150] The thickness of the molded article (including the stretched one) of the present invention is appropriately set according to the use, packaging form, required physical properties, etc.

[0151] 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, particularly preferably 50 to 200,000 μm. When the thickness of the molded article is too thin, the mechanical strength tends to decrease. Also, when the thickness of the molded article is too thick, the mechanical strength becomes excessive performance and an unnecessary amount of raw material is used, which is not economically preferable.

[0152] In this way, the molded article of the present invention can be obtained.

[0153] <Multi-layer structure> The multi-layer 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 further increase the strength or impart other functions by laminating with other base materials.

[0154] As the above-mentioned other base material, a layer made of an adhesive resin (hereinafter simply referred to as "adhesive resin layer"), a layer made of a polyamide resin (hereinafter simply referred to as "polyamide layer"), a layer made of EVOH (C) (hereinafter simply referred to as "EVOH layer"), and a layer made of a thermoplastic resin other than EVOH (hereinafter simply referred to as "thermoplastic resin layer") are preferably used.

[0155] When the layer structure of the multilayer structure is such that the resin composition layer of the present invention is R (R1, R2, ···), the EVOH layer is α (α1, α2, ···), the adhesive resin layer is β (β1, β2, ···), the polyamide layer is γ (γ1, γ2, ···), and the thermoplastic resin layer is δ (δ1, δ2, ···), any combination such as 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 / α3 / 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 is possible. Also, with respect to any EVOH layer (α), the layer structure of the layers laminated in one lamination direction and the layer structure of the layers laminated in the other direction may be the same (symmetric) or different (asymmetric) from each other. Further, with respect to any EVOH layer (α), the thickness of the layers laminated in one lamination direction and the thickness of the layers laminated in the other direction may be the same (symmetric) or different (asymmetric) from each other.

[0156] As the polyamide resin, known ones can be used. Specifically, for example, homopolymers such as polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecanamide (nylon 11), and polylauryl lactam (nylon 12) can be mentioned. Among them, polycapramide (nylon 6) is preferable. Further, as the copolymerized polyamide resin, there are 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), caprolactam / lauryl lactam copolymer (nylon 6 / 12), caprolactam / ω-aminononanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylene diammonium adipate copolymer (nylon 6 / 66), lauryl lactam / hexamethylene diammonium adipate copolymer (nylon 12 / 66), ethylenediamine adipamide / hexamethylene diammonium adipate copolymer (nylon 26 / 66), caprolactam / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon 66 / 610), ethylene ammonium adipate / hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (nylon 6 / 66 / 610) and other aliphatic polyamides, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymetaxylylene adipamide, hexamethylene isophthalamide / terephthalamide copolymer, poly-p-phenylene terephthalamide, poly-p-phenylene·3,4'-diphenyl ether terephthalamide and other aromatic polyamides, amorphous polyamides, those obtained by modifying these polyamide resins with aromatic amines such as methylene benzylamine and metaxylylenediamine, and metaxylylene diammonium adipate and the like. Alternatively, these end-modified polyamide resins may be used, and end-modified polyamide resins are preferably used.

[0157] Examples of the thermoplastic resin other than the above EVOH include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; polypropylene resins such as polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers; (unmodified) polyolefin resins such as polybutene, polypentene, polycyclic olefin resins (polymers having a cyclic olefin structure in the main chain and / or side chain); and modified olefin resins such as unsaturated carboxylic acid-modified polyolefin resins obtained by graft-modifying these polyolefins with an unsaturated carboxylic acid or its ester. The broad sense of polyolefin resins includes 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, and aromatic or aliphatic polyketones. These can be used alone or in combination of two or more.

[0158] Among these, considering hydrophobicity, polyolefin resins, polyester resins, and polystyrene resins, which are hydrophobic resins, are preferred. More preferably, polyolefin resins such as polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof are used. In particular, polycyclic olefin resins are preferably used as hydrophobic resins.

[0159] The ethylene and α-olefins of the above polyolefin resin may be plant-derived ethylene and α-olefins derived from bioethanol, or non-plant-derived, i.e., petroleum-derived ethylene and α-olefins, and these may be used in combination of two kinds. Since a wide variety of petroleum-derived α-olefins are available, the physical properties of the polyolefin resin can be easily adjusted by manufacturing using these. In addition, by using plant-derived ethylene and α-olefins, the biomass content of the final product can be further increased, and the environmental load can be reduced.

[0160] As a method for producing plant-derived ethylene and α-olefins, according to a conventional method, a sugar solution or starch obtained from plants such as sugarcane, corn, and sweet potato is fermented by microorganisms such as yeast to produce bioethanol, which is then heated in the presence of a catalyst, and plant-derived ethylene and α-olefins (1-butene, 1-hexene, etc.) can be obtained by an intramolecular dehydration reaction or the like. Subsequently, using the obtained plant-derived ethylene and α-olefins, a plant-derived polyethylene resin can be produced in the same manner as the production of a petroleum-derived polyethylene resin.

[0161] The production methods of plant-derived ethylene, α-olefins, and plant-derived polyethylene resins are described in detail, for example, in Japanese Patent Application Laid-Open No. 2011-506628. Examples of the plant-derived polyethylene resin preferably used in the present invention include Green PE manufactured by Braskem S.A.

[0162] In addition, as the adhesive resin which is the forming material of the adhesive resin layer, known ones can be used and can be appropriately selected according to the type of the thermoplastic resin used for other thermoplastic resins serving as the base material. Typically, a modified polyolefin-based polymer containing a carboxy group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin-based resin by an addition reaction, a graft reaction or the like can be mentioned. For example, maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate copolymer, maleic anhydride-modified polycyclic olefin-based resin, maleic anhydride graft-modified polyolefin-based resin, etc. These can be used alone or in combination of two or more kinds.

[0163] In the above-mentioned modified polyolefin-based polymer containing a carboxy group, the content of the unsaturated carboxylic acid or its anhydride is usually 0.001 to 3% by weight, preferably 0.01 to 1% by weight, particularly preferably 0.03 to 0.5% by weight with respect to the total amount of the modified polyolefin-based polymer containing a carboxy group. When the content (modification amount) of the unsaturated carboxylic acid or its anhydride is small, the adhesiveness tends to be insufficient. On the contrary, when it is large, a crosslinking reaction occurs and the moldability tends to deteriorate. These adhesive resins can also be blended with an ethylene-vinyl alcohol-based copolymer, a rubber / elastomer component such as polyisobutylene and ethylene-propylene rubber, and further with the resin of the polyolefin-based resin layer. In particular, it is also possible to blend a polyolefin-based resin different from the polyolefin-based resin which is the base of the adhesive resin.

[0164] In the above-mentioned adhesive resin layer, polyamide layer, and thermoplastic resin layer, within a range that does not inhibit the gist of the present invention (for example, 30% by weight or less, preferably 10% by weight or less), in addition to the aliphatic carboxylic acid (D) and aliphatic carboxylic acid metal salt (E) used in the present invention, conventionally known plasticizers (for example, ethylene glycol, glycerin, hexanediol, etc.), fillers, clay (for example, montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants (for example, alkali metal salts, alkaline earth metal salts of higher fatty acids having 8 to 30 carbon atoms, higher fatty acid esters (for example, methyl ester, isopropyl ester, butyl ester, octyl ester, etc. of higher fatty acids), higher fatty acid amides (for example, saturated fatty acid amides such as stearic acid amide, behenic acid amide, unsaturated fatty acid amides such as oleic acid amide, erucic acid amide, bis-fatty acid amides such as ethylene bis-stearic acid amide, ethylene bis-oleic acid amide, ethylene bis-erucic acid amide, ethylene bis-lauric acid amide), 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 resin, etc.), nucleating agents, antiblocking agents, ultraviolet absorbers, waxes, etc. may be contained. These can be used alone or in combination of two or more.

[0165] Moreover, it is also preferable to blend at least one selected from the group consisting of the thermoplastic resin (A), thermoplastic resin (B), EVOH (C), aliphatic carboxylic acid (D), aliphatic carboxylic acid metal salt (E), acetic acid and / or its salt (F) with the resin used in the above-mentioned adhesive resin layer and / or polyamide layer.

[0166] When producing a multilayer structure by laminating the above resin composition layer with the above other substrate, the lamination method can be carried out by a known method. For example, a method of melt-extrusion laminating another substrate to a film, sheet, etc. made of the resin composition of the present invention, conversely, a method of melt-extrusion laminating the resin composition of the present invention to another substrate, a method of co-extrusion molding the resin composition of the present invention and another substrate, a film (layer) made of the resin composition of the present invention and another substrate (layer) are each produced, and these are dry-laminated using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester-based compound, a polyurethane compound, etc., a method of applying a solution of the resin composition of the present invention onto another substrate and then removing the solvent, etc. can be mentioned. Among these, from the viewpoints of cost and environment, the method of co-extrusion molding is preferable.

[0167] Next, the above multilayer structure is subjected to a (heating) stretching treatment as necessary. The stretching treatment may be either uniaxial stretching or biaxial stretching. In the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. Also, as the stretching method, a method with a high stretching ratio among roll stretching method, tenter stretching method, tubular stretching method, stretch blow method, vacuum pressure forming method, etc. can be adopted. 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, the stretchability becomes poor, and if it is too high, it becomes difficult to maintain a stable stretching state.

[0168] In addition, for the purpose of imparting dimensional stability after stretching, heat setting may be carried out next. Heat setting can be carried out by well-known means. For example, the above stretched multilayer structure (stretched film) is heat-treated usually at 80 to 180 °C, preferably 100 to 165 °C, for usually about 2 to 600 seconds while maintaining a tension state.

[0169] Also, when using the multilayer stretched film obtained by using the resin composition of the present invention as a shrink film, in order to impart heat shrinkability, the above heat setting may not be performed, and for example, a treatment such as blowing cold air onto the stretched film for cooling and fixing may be carried out.

[0170] 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 a multilayer container, a drawing molding method is usually employed, and specifically, a vacuum molding method, a pressure air molding method, a vacuum-pressure air molding method, a plug assist type vacuum-pressure air molding method, etc. can be mentioned. Furthermore, when obtaining a tube- or bottle-shaped multilayer container from a multilayer parison (a hollow tubular preform before blowing), a blow molding method is employed, and specifically, an extrusion blow molding method (for example, a double-headed type, a mold moving type, a parison shift type, a rotary type, an accumulator type, a horizontal parison type, etc.), a cold parison type blow molding method, an injection blow molding method, a biaxial stretching blow molding method (for example, an extrusion type cold parison biaxial stretching blow molding method, an injection type cold parison biaxial stretching blow molding method, an injection molding in-line type biaxial stretching blow molding method, etc.), etc. can be mentioned. The multilayer laminate of the present invention can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box making, tube making, split processing, etc. as required.

[0171] The thickness of the multilayer structure (including the stretched one) of the present invention, and further the thicknesses of the resin composition layer, EVOH layer, polyamide resin layer, adhesive resin layer, and other thermoplastic resin layers constituting the multilayer structure are appropriately set according to the layer configuration, the type of thermoplastic resin, the type of polyamide resin, the type of adhesive resin, the use and packaging form, the required physical properties, etc.

[0172] 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, particularly preferably 50 to 2000 μm. When the total thickness of the multilayer structure is too thin, the gas barrier property and mechanical strength may decrease. Also, when the total thickness of the multilayer structure is too thick, the gas barrier property and mechanical strength become excessive performance, and unnecessary raw materials are used in excess, so it tends to be uneconomical. And the resin composition layer (R) is usually 5 to 3000 μm, preferably 10 to 2000 μm, particularly preferably 20 to 1000 μm, the EVOH layer (α) is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm, the thermoplastic resin layer (δ) is usually 5 to 3000 μm, preferably 10 to 2000 μm, particularly preferably 20 to 1000 μm, and the adhesive resin layer (β) is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm. In addition, the above numerical values are the total values of the thicknesses of the same kind of layers when at least one kind of layer among the resin composition layer (R), the EVOH layer (α), the adhesive resin layer (β), and the thermoplastic resin layer (δ) has two or more layers.

[0173] Furthermore, the ratio of the thickness of the EVOH layer (α) to the resin composition layer (R) in the multilayer structure (EVOH layer (α) / resin composition layer (R)) is, when there are multiple layers of each, the ratio of the thickest layers, usually 1 / 99 to 50 / 50, preferably 2 / 98 to 45 / 55, particularly preferably 5 / 95 to 40 / 60, especially preferably 10 / 90 to 35 / 65. When such a value is within the above range, the effects of the present invention tend to be obtained more significantly. When it is smaller than the above range, the gas barrier property and mechanical strength tend to be insufficient. When it is larger than the above range, the multilayer structure tends to be easily cracked.

[0174] In addition, the thickness ratio of the EVOH layer (α) to the polyamide layer (γ) in the multilayer structure (EVOH layer (α) / polyamide layer (γ)), ​​in terms of the ratio between the thickest layers when there are multiple layers, 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, when it is less than the above range, the gas barrier property tends to be insufficient, and when it is more than the above range, the mechanical strength tends to be insufficient.

[0175] In addition, 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)), in terms of the ratio between the thickest layers when there are multiple layers, 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, when it is less than the above range, the gas barrier property tends to be insufficient, and when it is more than the above range, the adhesive strength tends to be insufficient.

[0176] A multilayer structure containing a layer made of the above-mentioned resin composition is useful as a raw material for various packages 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, and the like. EXAMPLES

[0177] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention.

[0178] Prior to the examples, the following components were prepared.

[0179] [Thermoplastic resin (A)] Polypropylene (a1) (Japan Polypropylene Corporation "EA7AD", MFR 1.4g / 10min [230℃, load 2160g])

[0180] [Thermoplastic resin (B)] · Maleic anhydride graft-modified polypropylene (b1) (LyondellBasell's "PLEXAR PX6002", MFR 2.3 g / 10 min [230 °C, load 2160 g]) · Polyvinyl acetate resin (b2) [Ethylene-vinyl acetate copolymer (b3) (manufactured by Tosoh Corporation's "ULTRASEN 3B53A", vinyl acetate content: 28 wt%, MFR: 5.7 g / 10 min (190 °C, load 2160 g)) and saponified ethylene-vinyl acetate copolymer (b4) (manufactured by Tosoh Corporation's "MELSEN H0051K", ethylene content: 89 mol%, saponification degree: 99 mol%, MFR: 6.5 g / 10 min (190 °C, load 2160 g)), melt-kneaded at a weight ratio of (b3) / (b4) = 97.8 / 2.2.]

[0181] [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))

[0182] [Aliphatic carboxylic acid (D)] · Stearic acid (d1) · Caprylic acid (d2) · Lauric acid (d3) · Behenic acid (d4)

[0183] [Aliphatic carboxylic acid metal salt (E)] · Zinc stearate (e1) · Zinc caprylate (e2) · Zinc laurate (e3) · Zinc behenate (e4) · Magnesium stearate (e5) · Sodium stearate (e6) · Zinc gluconate trihydrate (e7) · Zinc citrate dihydrate (e8)

[0184] [Example 1] [Production of resin composition] As the thermoplastic resin (A), polypropylene (a1) pellets were used; as the thermoplastic resin (B), maleic anhydride graft-modified polypropylene (b1) pellets were used; as the EVOH (C), EVOH (c1) pellets were used; as the aliphatic carboxylic acid (D), stearic acid (d1) was used; and as the aliphatic carboxylic acid metal salt (E), zinc stearate (e1) was used. Also, 94% by weight of polypropylene (a1) based on the total of the resin composition, 1% by weight of maleic anhydride graft-modified polypropylene (b1) based on the total of the resin composition, 5% by weight of EVOH (c1) based on the total of the resin composition, 0.02 ppm in terms of carboxylic acid ions of stearic acid (d1) based on the total of the resin composition, and 0.5 ppm in terms of metal ions of zinc stearate (e1) based on the total of the resin composition were blended and dry-blended all at once. Then, using a φ32 mm twin-screw extrusion molding apparatus (L / D = 56, molding temperature = 210 °C), melt-kneading was carried out under the following melt-kneading conditions and re-pelletized to prepare a resin composition.

[0185] 〔Melt-kneading conditions of the resin composition〕 · Twin-screw extruder: diameter 32 mm, L / D = 56 (manufactured by Nippon Steel) · Extruder set temperature: C2 / C3 / C4 / C5 / C6 / C7 / C8 / C9 / C10 / C11 / C12 / C13 / C14 / C15 / C16 / H / D = 100 / 150 / 200 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 / 210 °C · Screw rotation speed: 330 ppm · Discharge rate: 25 kg / hour · Cooling of the strand: water cooling

[0186] For the resin composition obtained above, the following evaluations of moldability (eye gloss), color tone stability, and mechanical strength were carried out.

[0187] <Evaluation of the moldability (eye gloss) of the resin composition> When 10 kg of the resin composition was melt-kneaded as described above, the amount of the phase-separated product (gum) deposited near the die outlet was visually confirmed, and the moldability of the resin composition was evaluated based on the following evaluation criteria. A; No phase-separated product (gum) is observed near the die outlet. B; A very small amount of phase-separated product (gum) is slightly observed near the die outlet. C; A small amount of phase-separated product (gum) is observed near the die outlet. D; A large amount of phase-separated product (gum) is observed near the die outlet.

[0188] <Evaluation of Color Tone Stability of Resin Composition> The resin composition (pellets) obtained as described above was visually confirmed, and the color tone stability of the resin composition was evaluated based on the following evaluation criteria. A; No yellow or red discoloration is observed. B; Slight yellow or red discoloration is observed. C; Yellow or red discoloration is sufficiently observed. D; Yellow or red discoloration is significantly observed.

[0189] <Evaluation of Mechanical Strength of Resin Composition> The resin composition produced as described above was subjected to hot press molding at 230 °C using a manual hydraulic vacuum heating press machine (MIC-1867 type) manufactured by Imoto Seisakusho Co., Ltd. to produce a single-layer sheet with a thickness of 1 mm. Then, by cutting out the obtained single-layer sheet, a strip-shaped test piece with a thickness of 1 mm, a width of 15 mm, and a length of 100 mm was finally produced. The strip-shaped test piece produced as described above was sandwiched using a tensile testing machine "Autograph AGS-X manufactured by Shimadzu Corporation" under the conditions of 23 °C and 50% RH, with a gauge length of 50 mm, and a tensile test was performed at a test speed of 50 mm / min to evaluate the elastic modulus and the breaking strain. Such an evaluation was performed 5 times, and the average value was obtained. At this time, the higher the values of the elastic modulus and the breaking strain, the better the mechanical strength of the resin composition.

[0190] [Example 2] In Example 1, except that stearic acid (d1) was 0.11 ppm in terms of carboxylic acid ions relative to the total of the resin composition and zinc stearate (e1) was 2.3 ppm in terms of metal ions relative to the total of the resin composition, the resin composition was prepared in the same manner and evaluated in the same manner as in Example 1.

[0191] [Example 3] In Example 1, except that polypropylene (a1) was 90% by weight relative to the total of the resin composition, maleic anhydride graft-modified polypropylene (b1) was 1% by weight relative to the total of the resin composition, and further, as the thermoplastic resin (B), polyvinyl acetate-based resin (b2) was 4% by weight relative to the total of the resin composition, EVOH (c1) was 5% by weight relative to the total of the resin composition, stearic acid (d1) was 0.11 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc stearate (e1) was 2.3 ppm in terms of metal ions relative to the total of the resin composition, the resin composition was prepared in the same manner and evaluated in the same manner as in Example 1.

[0192] [Example 4] In Example 1, except that stearic acid (d1) was 0.45 ppm in terms of carboxylic acid ions relative to the total of the resin composition and zinc stearate (e1) was 9.3 ppm in terms of metal ions relative to the total of the resin composition, the resin composition was prepared in the same manner and evaluated in the same manner as in Example 1.

[0193] [Example 5] In Example 1, except that caprylic acid (d2) was used instead of stearic acid (d1) at 0.06 ppm in terms of carboxylic acid ions relative to the total of the resin composition and zinc caprylate (e2) was used instead of zinc stearate (e1) at 0.5 ppm in terms of metal ions relative to the total of the resin composition, the resin composition was prepared in the same manner and evaluated in the same manner as in Example 1.

[0194] [Example 6] In Example 5, the resin composition was prepared in the same manner except that capric acid (d2) was 0.31 ppm in terms of carboxylic acid ions based on the total amount of the resin composition, and zinc caprylate (e2) was 2.3 ppm in terms of metal ions based on the total amount of the resin composition, and evaluated in the same manner as in Example 1.

[0195] [Example 7] In Example 3, the resin composition was prepared in the same manner except that capric acid (d2) was used instead of stearic acid (d1) at 0.31 ppm in terms of carboxylic acid ions based on the total amount of the resin composition, and zinc caprylate (e2) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions based on the total amount of the resin composition, and evaluated in the same manner as in Example 1.

[0196] [Example 8] In Example 5, the resin composition was prepared in the same manner except that capric acid (d2) was 1.28 ppm in terms of carboxylic acid ions based on the total amount of the resin composition, and zinc caprylate (e2) was 9.3 ppm in terms of metal ions based on the total amount of the resin composition, and evaluated in the same manner as in Example 1.

[0197] [Example 9] In Example 1, the resin composition was prepared in the same manner except that lauric acid (d3) was used instead of stearic acid (d1) at 0.02 ppm in terms of carboxylic acid ions based on the total amount of the resin composition, and zinc laurate (e3) was used instead of zinc stearate (e1) at 0.5 ppm in terms of metal ions based on the total amount of the resin composition, and evaluated in the same manner as in Example 1.

[0198] [Example 10] In Example 9, the resin composition was prepared in the same manner except that lauric acid (d3) was 0.08 ppm in terms of carboxylic acid ions based on the total amount of the resin composition, and zinc laurate (e3) was 2.3 ppm in terms of metal ions based on the total amount of the resin composition, and evaluated in the same manner as in Example 1.

[0199] [Example 11] In Example 3, lauric acid (d3) was used instead of stearic acid (d1) at 0.08 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc laurate (e3) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, the procedure was the same to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0200] [Example 12] In Example 9, lauric acid (d3) was used at 0.33 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc laurate (e3) was used at 9.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, the procedure was the same to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0201] [Example 13] In Example 1, behenic acid (d4) was used instead of stearic acid (d1) at 0.03 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc behenate (e4) was used instead of zinc stearate (e1) at 0.5 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, the procedure was the same to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0202] [Example 14] In Example 13, behenic acid (d4) was used at 0.13 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc behenate (e4) was used at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, the procedure was the same to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0203] [Example 15] In Example 3, behenic acid (d4) was used instead of stearic acid (d1) at 0.13 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc behenate (e4) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, the procedure was the same to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0204] [Example 16] In Example 13, the procedure was the same except that behenic acid (d4) was 0.53 ppm in terms of carboxylic acid ions relative to the total amount of the resin composition and zinc behenate (e4) was 9.3 ppm in terms of metal ions relative to the total amount of the resin composition, and a resin composition was prepared and evaluated in the same manner as in Example 1.

[0205] [Comparative Example 1] In Example 1, the procedure was the same except that stearic acid (d1) and zinc stearate (e1) were not used, and a resin composition was prepared and evaluated in the same manner as in Example 1.

[0206] [Comparative Example 2] In Example 3, the procedure was the same except that stearic acid (d1) and zinc stearate (e1) were not used, and a resin composition was prepared and evaluated in the same manner as in Example 1.

[0207] [Comparative Example 3] In Example 2, the procedure was the same except that stearic acid (d1) was not used, and a resin composition was prepared and evaluated in the same manner as in Example 1.

[0208] [Comparative Example 4] In Example 5, the procedure was the same except that 69% by weight of polypropylene (a1) was used relative to the total amount of the resin composition, 30% by weight of EVOH (c1) was used relative to the total amount of the resin composition, caprylic acid (d2) was 7.7 ppm in terms of carboxylic acid ions relative to the total amount of the resin composition, and zinc caprylate (e2) was 55.8 ppm in terms of metal ions relative to the total amount of the resin composition, and a resin composition was prepared and evaluated in the same manner as in Example 1.

[0209] [Comparative Example 5] In Example 7, polypropylene (a1) was 65% by weight based on the total of the resin composition, EVOH (c1) was 30% by weight based on the total of the resin composition, caprylic acid (d2) was 7.7 ppm in terms of carboxylic acid ion based on the total of the resin composition, and zinc caprylate (e2) was 55.8 ppm in terms of metal ion based on the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0210] [Comparative Example 6] In Example 1, stearic acid (d1) was 0.69 ppm in terms of carboxylic acid ion based on the total of the resin composition, and magnesium stearate (e5) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ion based on the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0211] [Comparative Example 7] In Comparative Example 6, polypropylene (a1) was 90% by weight based on the total of the resin composition, polyvinyl acetate resin (b2) was 4% by weight based on the total of the resin composition, EVOH (c1) was 5% by weight based on the total of the resin composition, stearic acid (d1) was 0.69 ppm in terms of carboxylic acid ion based on the total of the resin composition, and magnesium stearate (e5) was 2.3 ppm in terms of metal ion based on the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0212] [Comparative Example 8] In Example 1, stearic acid (d1) was 0.15 ppm in terms of carboxylic acid ion based on the total of the resin composition, and sodium stearate (e6) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ion based on the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0213] [Comparative Example 9] In Example 3, stearic acid (d1) was used at 0.15 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and sodium stearate (e6) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0214] [Comparative Example 10] In Example 1, stearic acid (d1) was used at 0.11 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc gluconate trihydrate (e7) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0215] [Comparative Example 11] In Example 3, zinc gluconate trihydrate (e7) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0216] [Comparative Example 12] In Example 1, stearic acid (d1) was used at 0.11 ppm in terms of carboxylic acid ions relative to the total of the resin composition, and zinc citrate dihydrate (e8) was used instead of zinc stearate (e1) at 2.3 ppm in terms of metal ions relative to the total of the resin composition. Otherwise, it was carried out in the same manner to prepare a resin composition, which was evaluated in the same manner as in Example 1.

[0217] The evaluation results of the examples and comparative examples are shown in Table 1 and Table 2.

[0218]

Table 1

[0219]

Table 2

[0220] In the resin compositions of Comparative Examples 1 to 12 that do not have the characteristic configuration of the present invention, the mechanical strength, color tone stability, and moldability (surface gloss) were low. On the other hand, in the resin compositions of Examples 1 to 16 having the characteristic configuration of the present invention, the mechanical strength and color tone stability were excellent. Furthermore, the moldability (surface gloss) during melt molding was excellent.

[0221] In the above examples, specific forms of the present invention were shown, but the above examples are merely illustrative and should not be construed in a limiting sense. Various modifications obvious to those skilled in the art are intended to be within the scope of the present invention.

Industrial Applicability

[0222] The resin composition of the present invention is excellent in mechanical strength and color tone stability, and the generation of surface gloss during melt molding is highly suppressed. Therefore, the multilayer structure and molded body containing the layer made of the above resin composition are useful as raw materials for various packaging bodies such as general foods, seasonings such as mayonnaise and dressing, fermented foods such as miso, oil and fat foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

Claims

1. A resin composition containing a thermoplastic resin (A) not containing a polar group, a thermoplastic resin (B) containing a polar group, an ethylene-vinyl alcohol copolymer (C) having an ethylene content of 20 to 60 mol%, an aliphatic carboxylic acid (D) having 3 or more carbon atoms, and an aliphatic carboxylic acid metal salt (E) which is a metal salt of the above aliphatic carboxylic acid (D), wherein the thermoplastic resin (A) not containing a polar group is at least one selected from polyolefin resins and polystyrene resins not containing a hydroxyl group, a carboxy group, an amino group, and an amide group, the thermoplastic resin (B) containing a polar group is at least one selected from polyolefin resins containing a carboxy group or an acid anhydride group and polyvinyl acetate resins, the metal species of the aliphatic carboxylic acid metal salt (E) is at least one selected from elements belonging to the 4th period d-block of the long-period type periodic table, the content of the thermoplastic resin (A) not containing a polar group is 66 to 99% by weight based on the total of the resin composition, the content of the thermoplastic resin (B) containing a polar group is 0.1 to 50% by weight based on the total of the resin composition, the content of the ethylene-vinyl alcohol copolymer (C) having an ethylene content of 20 to 60 mol% is 0.1 to 25% by weight based on the total of the resin composition, the content in terms of carboxylic acid ions of the aliphatic carboxylic acid (D) having 3 or more carbon atoms is 0.0001 to 150 ppm based on the total of the resin composition, the content in terms of metal ions of the aliphatic carboxylic acid metal salt (E) is 0.01 to 90 ppm based on the total of the resin composition. A resin composition characterized by this.

2. The resin composition according to Claim 1, characterized in that the thermoplastic resin (A) not containing a polar group is at least one selected from polyethylene, polypropylene, and polystyrene.

3. Furthermore, it contains acetic acid and / or its salt (F), and the content of the acetic acid and / or its salt (F) in terms of acetate ions is 0.01 to 1000 ppm with respect to the total of the resin composition. The resin composition according to claim 1 or 2, characterized in that.

4. A method for producing a resin composition, characterized by melt-kneading and pelletizing the resin composition according to any one of claims 1 to 3.

5. A molded article, characterized by using the resin composition according to any one of claims 1 to 3.

6. A multilayer structure having at least one layer composed of the resin composition according to any one of claims 1 to 3.

7. A package, characterized by being composed of the multilayer structure according to claim 6.

Images