JP7167423B2 - Resin composition and multilayer structure using the same - Google Patents

Description

The present invention relates to a resin composition using an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH") and a multilayer structure using the same, and more specifically, A resin composition capable of forming a multilayer structure in which appearance defects are suppressed even when multilayer co-extrusion molding is applied, and deterioration of color tone during melt molding is improved, and a resin composition using the same It relates to a multi-layered structure including material layers.

Packaging materials for packaging foods and various articles are often required to have gas barrier properties against oxygen and the like. This is to prevent the contents of the package from being oxidatively deteriorated by oxygen or the like, and to maintain the freshness of the food for a long time. For this reason, conventional packaging materials are provided with a gas barrier layer to prevent permeation of oxygen and the like.

Examples of the gas barrier layer include a gas barrier layer made of an inorganic substance and a gas barrier layer made of an organic substance. As the gas barrier layer made of an inorganic substance, a metal layer such as an aluminum foil or an aluminum vapor deposition layer, or a metal compound layer such as a silicon oxide vapor deposition layer or an aluminum oxide vapor deposition layer is used. However, metal layers such as aluminum foil and vapor-deposited aluminum layers have drawbacks such as the fact that the contents of the package cannot be seen and that they are difficult to dispose of.

On the other hand, as a gas barrier layer made of an organic substance, a layer made of a polyvinylidene chloride polymer or a layer made of a vinyl alcohol polymer such as polyvinyl alcohol or EVOH is used. In recent years, polyvinylidene chloride-based polymers have been greatly reduced in usage because there is a risk of generation of harmful chlorine compounds when they are incinerated. A layer composed of a vinyl alcohol polymer is transparent and has the advantage of being less problematic in terms of disposal, and is therefore widely used in packaging materials.

For example, the packaging material may be a multi-layer structure in which a layer made of EVOH is used as an intermediate layer and a thermoplastic resin other than EVOH is laminated via an adhesive resin layer or a polyamide resin layer. As described above, such a multilayer structure can be used as a film or sheet as a packaging material for food packaging materials, pharmaceutical packaging materials, industrial chemical packaging materials, agricultural chemical packaging materials, etc., by utilizing its excellent gas barrier properties and transparency. , or molded into containers such as bottles for use.

In molding such a multilayer structure, a melt molding method is generally applied from the viewpoint of productivity. However, since EVOH is rich in hydroxyl groups, it is easily deteriorated by heat, and it is known that a compounding agent is added for the purpose of improving melt moldability.

In general, for the purpose of improving the moldability of EVOH, for example, Patent Document 1 discloses an ethylene-vinyl acetate copolymer saponified product (A) having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more. A metal having a specific chemical formula obtained by heating one or more aliphatic monocarboxylic acids having 12 to 30 carbon atoms and oxides or hydroxides of group 2 metals of the periodic table by a dry direct method. It is described that by using a resin composition comprising soap (B), excellent thermal stability and workability (long-run moldability, retention prevention property, purging property) are obtained (Patent Document 1).

In recent years, there has been a strong demand for a sense of security in the contents, so there is a tendency to prefer a multilayer structure with high visibility (transparency) so that the contents can be confirmed even from the outside. On the other hand, Patent Document 2 discloses that a saponified ethylene-vinyl ester copolymer other than a saponified ethylene-vinyl ester copolymer is added to at least one surface of a layer containing a saponified ethylene-vinyl ester copolymer via an adhesive resin layer. A multilayer structure comprising laminated thermoplastic resin layers, wherein the thickness (X) of the interface layer at the lamination interface between the layer containing the saponified ethylene-vinyl ester copolymer and the adhesive resin layer is , By using a multilayer structure characterized by a thickness of 50 to 400 nm per interface surface, by controlling the resin fluidity at the interface of the EVOH layer / adhesive resin layer, the EVOH layer / adhesive resin layer A technique is disclosed for obtaining a multilayer structure in which poor appearance due to interface roughness occurring at the lamination interface is reduced, and in particular, a decrease in image definition is small.

JP-A-2000-290455 WO2016/148271

However, due to recent advances in molding technology (e.g., diversification of feed block and die shapes, high functionality of molding equipment, etc.) and multi-layered structures (e.g., increased number of layers), There has been a demand for further improvement in the appearance of the resulting multilayer structure, particularly in the transparency of the multilayer structure, when extruded.

Therefore, under such a background, the present invention is a resin composition capable of forming a multilayer structure in which the occurrence of poor appearance is suppressed and the deterioration of transparency during melt molding is improved, and a resin composition using the same. An object of the present invention is to provide a multilayer structure including a resin composition layer.

However, in view of the above circumstances, the inventor of the present invention has made intensive studies and found that EVOH (A) has a hydroxy group-containing monovalent carboxylic acid metal salt (B) having a specific medium number of carbon atoms. The present invention was completed by using the product.

That is, the first gist of the present invention is a resin composition containing EVOH (A) and a monocarboxylic acid metal salt (B) having a hydroxyl group and having 2 to 17 carbon atoms.

The second gist of the present invention is a multilayer structure in which a thermoplastic resin layer other than the resin composition is laminated on at least one surface of a layer made of the resin composition via an adhesive resin layer. A third aspect of the present invention is a multilayer structure in which a polyamide-based resin layer is laminated on at least one surface of a resin composition layer made of the above resin composition.

The present invention is a resin composition comprising EVOH (A) and a monocarboxylic acid metal salt (B) having a hydroxyl group and having 2 to 17 carbon atoms. Therefore, the multilayer structure obtained using the above resin composition is prevented from having poor appearance due to interface roughness occurring at the lamination interface of, for example, the EVOH layer/adhesive resin layer and/or the EVOH layer/polyamide resin layer. and an excellent multi-layered structure with highly improved transparency during melt molding.

The configuration of the present invention will be described in detail below, but these show examples of preferred embodiments and are not limited to these contents.

The present invention includes EVOH (A) and a monovalent carboxylic acid metal salt (B) having a hydroxyl group and having 2 to 17 carbon atoms (hereinafter, such a component may be referred to as a metal salt (B)). It is a resin composition characterized by containing

<EVOH (A)>
EVOH (A) used in the present invention will be described.
EVOH (A) used in the present invention is usually a resin obtained by copolymerizing ethylene and a vinyl ester monomer and then saponifying the copolymer, and is a water-insoluble thermoplastic resin. Any known polymerization method such as solution polymerization, suspension polymerization, and emulsion polymerization can be used, but solution polymerization using methanol as a solvent is generally used. Saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.
That is, the EVOH (A) used in the present invention is mainly composed of ethylene structural units and vinyl alcohol structural units, and optionally contains a small amount of residual vinyl ester structural units that have not been saponified.

As the vinyl ester-based monomer, vinyl acetate is typically used because of its easy availability on the market and good efficiency in removing impurities during production. In addition, for example, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and benzoin. Examples thereof include aromatic vinyl esters such as vinyl acid, and aliphatic vinyl esters usually having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, particularly preferably 4 to 7 carbon atoms. These are usually used alone, but if necessary, multiple types may be used at the same time.

The content of ethylene structural units in EVOH (A) is a value measured based on ISO14663, and is usually 20 to 60 mol%, preferably 25 to 50 mol%, particularly preferably 25 to 40 mol%. If the content is too low, the gas barrier properties and melt moldability at high humidity will tend to be low, and if it is too high, the gas barrier properties will tend to be low.

The saponification degree of the vinyl ester component in EVOH (A) is a value measured based on JIS K6726 (however, EVOH is a solution uniformly dissolved in water/methanol solvent), and is usually 90 to 100 mol%. It is preferably 95 to 100 mol %, particularly preferably 99 to 100 mol %. If the degree of saponification is too low, gas barrier properties, thermal stability, moisture resistance, etc. tend to deteriorate.

The melt flow rate (MFR) (210° C., load 2160 g) of the EVOH (A) is usually 0.5 to 100 g/10 minutes, preferably 1 to 50 g/10 minutes, particularly preferably 3 to 35 g. /10 minutes. If the MFR is too high, the film formability tends to deteriorate. Also, if the MFR is too low, melt extrusion tends to be difficult.

The EVOH (A) used in the present invention may further contain structural units derived from the following comonomers within a range (for example, 10 mol % or less) that does not impair the effects of the present invention.
The comonomers include, for example, olefins such as propylene, 1-butene and isobutene; , 3,4-dihydroxy-1-butene, 5-hexene-1,2-diol, 2-methylenepropane-1,3-diol and other hydroxy group-containing olefins and their esters, 3,4- diacetoxy-1-butene, 2,3-diacetoxy-1-allyloxypropane, 2-acetoxy-1-allyloxy-3-hydroxypropane, 3-acetoxy-1-allyloxy-2-hydroxypropane; 1,3-diacetoxy- Hydroxymethylvinylidene diacetates such as 2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, 1,3-dibutyronyloxy-2-methylenepropane, glycerin monoallyl ether, glycerin monovinyl ether, glycerin Glycerin monounsaturated alkyl ethers such as monoisopropenyl ether, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, and (anhydrous) itaconic acid, salts thereof, or carbon mono- or dialkyl esters having numbers 1 to 18, acrylamide, N-alkylacrylamide having 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or salts thereof, acrylamidopropyldimethylamine or salts thereof, or Acrylamides such as quaternary salts thereof, methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or salts thereof, methacrylamidopropyldimethylamine or its salts methacrylamides such as acid salts or quaternary salts thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; 18 vinyl ethers such as alkyl vinyl ether, hydroxyalkyl vinyl ether and alkoxyalkyl vinyl ether; vinyl halide compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; Allyl halides such as allyl acetate and allyl chloride allyl compounds, allyl alcohol such as allyl alcohol and dimethoxyallyl alcohol, comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.

In addition, EVOH that has been "post-modified" such as urethanized, acetalized, cyanoethylated, oxyalkylenated, etc. can also be used.

In particular, EVOH having a primary hydroxy group in the side chain is preferable in terms of good secondary moldability while maintaining gas barrier properties. EVOH having a 1,2-diol in the side chain is particularly preferred.

The EVOH having a 1,2-diol in the side chain contains a 1,2-diol structural unit in the side chain. The 1,2-diol structural unit is specifically a structural unit represented by the following general formula (1).

〔上記一般式（１）において、Ｒ¹，Ｒ²およびＲ³は、それぞれ独立して水素原子または有機基を示し、Ｘは単結合または結合鎖を示す。Ｒ⁴，Ｒ⁵およびＲ⁶は、それぞれ独立して水素原子または有機基を示す。〕

[In the above general formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic group, and X represents a single bond or a bond chain. R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom or an organic group. ]

Examples of the organic group in the 1,2-diol structural unit represented by the general formula (1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and tert-butyl. saturated hydrocarbon groups such as groups, aromatic hydrocarbon groups such as phenyl groups and benzyl groups, halogen atoms, hydroxy groups, acyloxy groups, alkoxycarbonyl groups, carboxyl groups, sulfonic acid groups and the like.

In particular, when the 1,2-diol structural unit represented by the general formula (1) is contained, the content is usually 0.1 to 20 mol%, further 0.1 to 15 mol%, particularly 0.1 to 20 mol%. 1 to 10 mol % is preferred.

In addition, the EVOH (A) used in the present invention may be a mixture with other different EVOH. Examples include those with different contents of 1,2-diol structural units represented, those with different degrees of saponification, those with different melt flow rates (MFR), and those with different other copolymerization components.

<Hydroxy Group-Containing Monovalent Carboxylic Acid Metal Salt (B)>
In the present invention, a monovalent carboxylic acid metal salt (B) having a hydroxyl group and having 2 to 17 carbon atoms is used. The anion constituting the metal salt (B) is an anion derived from a monovalent carboxylic acid, that is, one carboxyl group, has a hydroxyl group, and has 2 to 17 carbon atoms. The affinity between EVOH (A) and the metal salt (B) is increased by using a monovalent carboxylic acid metal salt having a hydroxyl group and a specific medium number of carbon atoms as the metal salt (B), For example, an excellent multi-layer that suppresses poor appearance due to interface roughness occurring at the lamination interface of EVOH layer/adhesive resin layer and/or EVOH layer/polyamide resin layer, and has highly improved transparency during melt molding. It is assumed that a structure is obtained.

Examples of such metal salts (B) include monovalent aliphatic carboxylic acid metal salts having a hydroxyl group such as glycolic acid, gluconic acid, lactic acid, glyceric acid, hydroxybutyric acid, and hydroxylauric acid; salicylic acid, syringic acid, protocatechuic acid, monovalent aromatic carboxylic acid metal salts having a hydroxy group such as gentisic acid, gallic acid, mandelic acid, benzilic acid, phlorethic acid, etc., and monovalent aliphatic carboxylic acids having a hydroxy group are preferable from the viewpoint of productivity; It is a metal salt, more preferably a metal salt of gluconate.

The number of carbon atoms in the metal salt (B) is preferably 2-15, particularly preferably 3-10. When such a value is within the above range, the effects of the present invention tend to be obtained more remarkably.
The valence of the hydroxy group of the metal salt (B) is generally 1 to 3, preferably 1 from the viewpoint of productivity.

Examples of the metal species of the metal salt (B) include monovalent metals: alkali metals such as sodium and potassium; polyvalent metals: alkaline earth metals such as magnesium, calcium and barium; Metals selected from groups 10 to 12 can be mentioned. A polyvalent metal is preferable in that the effects of the present invention can be obtained more remarkably. More preferably, it is a metal selected from Groups 10 to 12 of the Periodic Table, such as alkaline earth metals such as magnesium, calcium, and barium, and zinc, and more preferably selected from Groups 10 to 12 of the Periodic Table, such as zinc. It is a metal that can be Metals selected from Groups 10 to 12 of the Periodic Table are more preferably metals selected from Period 4 of the d block of the Periodic Table, specifically nickel, copper and zinc.

That is, the metal salt (B) is preferably a polyvalent metal salt of a monovalent aliphatic carboxylic acid having a hydroxy group or a monovalent aromatic carboxylic acid having a hydroxy group, more preferably a monovalent aliphatic carboxylic acid having a hydroxy group. a polyvalent metal salt of group carboxylic acid, more preferably a polyvalent metal salt of gluconic acid, more preferably an alkaline earth metal salt of gluconic acid and a metal salt selected from groups 10 to 12 of the periodic table and most preferably zinc gluconate.

In addition, the metal salt (B) may be an anhydride or a hydrate, and from the viewpoint of economy and availability, a hydrate is preferred, and a saturated hydrate is most preferred. .

The content of the metal salt (B) is preferably 0.01 to 5 parts, preferably 0.03 to 3 parts, more preferably 0.05 to 1 part per 100 parts of EVOH (A). part, more preferably 0.09 to 1 part. If the content is too small, the effect of improving transparency during melt molding tends to be reduced, and if it is too large, the thermal stability and color tone stability tend to be reduced.

<Other thermoplastic resin (C)>
The resin composition of the present invention may contain a thermoplastic resin other than EVOH (A) as a resin component within a range of usually 30% by weight or less based on EVOH (A). Hereinafter, thermoplastic resins other than EVOH (A) are referred to as "other thermoplastic resins (C)".

Examples of the other thermoplastic resin (C) include linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, Ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer , polybutene, polypentene and other olefin homo- or copolymers, polycyclic olefins, or homo- or copolymers of these olefins graft-modified with unsaturated carboxylic acids or their esters. Thermoplastic resins such as system resins, polyesters, polyamides, copolyamides, polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, and chlorinated polypropylene.

In particular, when a multilayer structure is produced using the resin composition of the present invention and used as a food packaging material, the EVOH layer is eluted at the end of the packaging material after hot water sterilization of the packaging material. For the purpose of preventing this, it is preferable to blend a polyamide-based resin as another thermoplastic resin (C). Polyamide-based resins can form a network structure through the interaction of amide bonds with OH groups and/or ester groups of EVOH, thereby preventing elution of EVOH during hot water treatment. . Therefore, when the resin composition of the present invention is used as a packaging material for retort food or boiled food, it is preferable to incorporate a polyamide-based resin.

A well-known thing can be used as said polyamide-type resin.
Specifically, for example, polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), polylauryllactam (nylon 12 ) and other homopolymers. Copolymerized polyamide resins include polyethylenediamineadipamide (nylon 26), polytetramethyleneadipamide (nylon 46), polyhexamethyleneadipamide (nylon 66), polyhexamethylenesebacamide (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/hexamethylene Aliphatic polyamides such as diammonium adipate/hexamethylenediammonium sebacate copolymer (nylon 6/66/610), polyhexamethyleneisophthalamide, polyhexamethyleneterephthalamide, polymetaxylyleneadipamide, hexamethyleneisophthalate Amide/terephthalamide copolymers, aromatic polyamides such as poly-P-phenylene terephthalamide and poly-P-phenylene/3-4'diphenyl ether terephthalamide, amorphous polyamides, these polyamide resins with methylenebenzylamine , meta-xylylene diamine modified with an aromatic amine such as meta-xylylene diamine and meta-xylylene diammonium adipate. Alternatively, these terminal-modified polyamide-based resins may be used, preferably terminal-modified polyamide-based resins.

The terminal-modified polyamide-based resin is specifically, for example, a terminal-modified polyamide-based resin modified with a hydrocarbon group having 1 to 22 carbon atoms, and a commercially available one may be used. More specifically, for example, the number of terminal COOH groups [X] of the terminal-modified polyamide resin and terminal CONR ¹ R ² groups (where R ¹ is a hydrocarbon group having 1 to 22 carbon atoms, R ² is a hydrogen atom or The number [Y] of hydrocarbon groups having 1 to 22 carbon atoms) is
100×Y/(X+Y)≧5
A terminal-modified polyamide resin that satisfies is preferably used.

The terminal-modified polyamide resin is obtained by modifying the carboxyl groups of a normal unmodified polyamide resin with an N-substituted amide with a terminal modifier, and the total number of carboxyl groups contained in the polyamide resin before modification is It is a polyamide resin that has been modified by 5% or more. If the amount of such modification is too small, a large number of carboxyl groups will be present in the polyamide-based resin, and such carboxyl groups will react with EVOH during melt molding to generate gels, etc., and the appearance of the resulting film will tend to be poor. Tend. Such a terminal-modified polyamide resin can be produced, for example, by the method described in JP-B-8-19302.

When a polyamide resin is used as the other thermoplastic resin (C), the content ratio of EVOH/polyamide resin is usually 99/1 to 70/30, preferably 97/3 to 75/25 by weight. , particularly preferably 95/5 to 85/15. If the weight ratio of the polyamide-based resin is too large, the long-run moldability and gas barrier properties tend to deteriorate. If the weight ratio of the polyamide-based resin is too small, the effect of suppressing the elution of EVOH after hot water treatment tends to decrease.

<Inorganic filler (D)>
The resin composition of the present invention contains EVOH (A) (optionally, another thermoplastic resin (C)), a metal salt (B), and an inorganic filler (D) for the purpose of improving gas barrier properties. may contain.

The inorganic filler (D) is preferably a plate-like inorganic filler from the viewpoint of exhibiting more gas barrier properties. Double salts such as mica and smectite, which are silicate minerals, and talc, which is composed of magnesium hydroxide and silicate. Among these, kaolin is preferably used. The type of kaolin is not particularly limited, and may or may not be calcined, but calcined kaolin is preferred.

By blending the inorganic filler (D), the gas barrier properties of the resin composition are further improved. Especially in the case of the plate-like inorganic filler, since it has a multilayer structure, in the case of film molding, the plate-like surface of the plate-like inorganic filler tends to be oriented in the plane direction of the film. Thus, it is presumed that the plate-like inorganic filler oriented in the plane direction particularly contributes to blocking oxygen of the resin composition layer (for example, film).

The content of the inorganic filler (D) is generally 1 to 20% by weight, preferably 3 to 18% by weight, more preferably 5 to 15% by weight, relative to EVOH (A). If the content is too small, the effect of improving the gas barrier property tends to decrease, and if it is too large, the transparency tends to decrease.

<Oxygen Absorber (E)>
The resin composition of the present invention contains EVOH (A), metal salt (B), and oxygen absorber (E) for the purpose of improving gas barrier properties after hot water sterilization (retort treatment). may

The oxygen absorber (E) is a compound that captures oxygen faster than the contents of the package. Specific examples include inorganic oxygen absorbents, organic oxygen absorbents, composite oxygen absorbents using a combination of an inorganic catalyst (transition metal catalyst) and an organic compound, and the like.

Examples of the inorganic oxygen absorber include metals and metal compounds, which absorb oxygen by reacting with them. As the metal, a metal having a higher ionization tendency than hydrogen (Fe, Zn, Mg, Al, K, Ca, Ni, Sn, etc.) is preferable, and iron is representative. These metals are preferably used in powder form. As the iron powder, conventionally known ones such as reduced iron powder, atomized iron powder, electrolytic iron powder, etc. can be used without particular limitation, regardless of the production method thereof. Moreover, the iron to be used may be iron that has been once oxidized and subjected to a reduction treatment. Further, as the metal compound, an oxygen-deficient metal compound is preferable. Here, the oxygen-deficient metal compound includes cerium oxide (CeO2), titanium oxide (TiO2), zinc oxide (ZnO), and the like. Oxygen-deficient state occurs when it is exposed to the atmosphere, and the oxygen-absorbing ability is exhibited by reacting with oxygen in the atmosphere. Such metals and metal compounds preferably contain metal halides and the like as reaction accelerators.

Examples of the organic oxygen absorbent include hydroxyl group-containing compounds, quinone compounds, double bond-containing compounds, and oxidizable resins. Oxygen can be absorbed by reaction of oxygen with hydroxyl groups and double bonds contained in these. Preferred examples of the organic oxygen absorber include ring-opening polymers of cycloalkenes such as polyoctenylene, conjugated diene polymers such as butadiene, and cyclized products thereof.

The content of such oxygen absorbent (E) is usually 1 to 30% by weight, preferably 3 to 25% by weight, more preferably 5 to 20% by weight, relative to EVOH (A). be.

<Other additives (F)>
In addition to the above components, the resin composition of the present invention may optionally contain ethylene glycol, within a range that does not impair the effects of the present invention (for example, 5% by weight or less of the entire resin composition), Plasticizers such as aliphatic polyhydric alcohols such as glycerin and hexanediol; higher fatty acids (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid metals other than metal salts (B) Salts (aluminum salts of higher fatty acids such as stearic acid, calcium salts, magnesium salts, barium salts, etc.), higher fatty acid esters (methyl esters of higher fatty acids, isopropyl esters, butyl esters, octyl esters, etc.), higher fatty acid amides (stearic acid saturated aliphatic amides such as amides and behenic acid amides; unsaturated fatty acid amides such as oleic acid amides and erucic acid amides; bis fatty acid amide), low molecular weight polyolefin (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10000, or low molecular weight polypropylene); lubricants such as fluoroethylene resin; antiblocking agent; antioxidant; coloring agent; antistatic agent; Antimicrobial agents; insoluble inorganic salts (e.g., hydrotalcite, etc.), hydrate-forming metal salts other than the metal salt (B); (e.g., disodium succinate, sodium tartrate, sodium citrate, calcium citrate, Carboxylate salts such as zinc citrate and magnesium citrate; sulfate salts such as sodium sulfate, potassium sulfate, and magnesium sulfate), surfactants, and known additives such as conjugated polyene compounds can be appropriately added.

The base resin in the entire resin composition of the present invention is EVOH (A). Therefore, the amount of EVOH (A) is usually 70% by weight or more, preferably 80% by weight or more, particularly preferably 90% by weight or more, based on the total resin composition. If the amount is too small, gas barrier properties tend to deteriorate.

<Method for preparing resin composition>
The method for producing the resin composition of the present invention is not particularly limited as long as the metal salt (B) is present inside and/or on the outer surface of the resin composition.

"Method for making the metal salt (B) exist inside the resin composition"
As a method for making the metal salt (B) exist inside the resin composition, specifically, (a) a method of mixing components (A) and (B) together and then melt-kneading them, (b) (A) and a method of uniformly dissolving and mixing component (B) in a soluble solvent and then removing the solvent. A more detailed description will be given, but the present invention is not limited to this.

The melt-kneading method in (a) above can be performed using known melt-kneading devices such as a kneader ruder, an extruder, a mixing roll, a Banbury mixer, and a plastomill. is preferably melt-kneaded at 150 to 300 ° C. (further 180 to 280 ° C.) for about 1 to 20 minutes, especially using a single-screw or twin-screw extruder because pellets can be easily obtained. Moreover, it is also preferable to provide a vent suction device, a gear pump device, a screen device, etc., as required. In particular, in order to remove moisture and by-products (pyrolytic low-molecular-weight substances, etc.), the extruder is provided with one or more vent holes to suck under reduced pressure, or to prevent oxygen from entering the extruder. For this purpose, an inert gas such as nitrogen is continuously supplied into the hopper to obtain a resin composition of excellent quality in which thermal coloration and thermal deterioration are reduced.

In addition, the method of supplying to a melt kneading device such as an extruder is not particularly limited, and 1) a method of dry blending components (A) and (B) and supplying them collectively to an extruder, 2) ( A) A method of supplying a solid component (B) to an extruder where the component is supplied and melted (solid side feed method), 3) A method where the component (A) is supplied to an extruder and melted. (melt side feed method) and the like can be mentioned, but method 1) is practical in view of the simplicity of the apparatus, the cost of the blend, and the like.

The resin composition obtained by the above methods (a) and (b) can be melt-kneaded to obtain a direct melt-molded product. It is preferable to produce resin composition pellets later and subject them to a melt molding method to obtain a melt molded product. From the point of view of economy, a method of melt-kneading using an extruder, extruding into strands, and cutting them into pellets is preferred.

The shape of the pellet is, for example, spherical, oval, cylindrical, cubic, cuboid, etc., and is usually oval or cylindrical. From the viewpoint of , in the case of an oval shape, the diameter is usually 1 to 6 mm, preferably 2 to 5 mm, and the height is usually 1 to 6 mm, preferably 2 to 5 mm. It is 1-6 mm, preferably 2-5 mm, and the length is usually 1-6 mm, preferably 2-5 mm.

The water content of the resin composition or pellets is preferably 0.001 to 5% by weight (further 0.01 to 2% by weight, particularly 0.1 to 1 part by weight), and the water content If the ratio is too low, the long-run moldability tends to deteriorate, and if it is too high, foaming may occur during extrusion molding, which is not preferable.

"Method of making the metal salt (B) exist on the outer surface of the resin composition"
Subsequently, as a method for making the metal salt (B) exist on the outer surface of the resin composition, specifically, (1) EVOH (A) having a water content of 0.1 to 5% by weight is blended with the component (B). (2) a method of blending the (B) component melted into the heated EVOH (A); (3) a method of blending the (B) component into the EVOH (A) mixed with a small amount of silicone oil or the like; (4) A method of blending component (B) with EVOH (A) impregnated with a liquid plasticizer such as glycerin. (5) A method of blending component (B) dissolved in a small amount of solvent with EVOH (A). etc. can be cited, but the method (1) is industrially preferably employed, and this method will be described in more detail, but it is not limited to this.

When attaching the component (B) to the surface of the resin composition, in order to improve the adhesiveness of the component (B), the moisture content of the pellets is adjusted to 0.1 to 5 wt% (further 0.5 to 4 % by weight, particularly 1 to 3% by weight). If the water content is less than 0.1% by weight, component (B) is likely to fall off and the distribution of adhesion (attachment) becomes uneven. If the amount exceeds 5% by weight, the component (B) aggregates and the adhesion (attachment) distribution becomes non-uniform, which is not preferable.

Incidentally, the moisture content of the resin composition pellets referred to here is measured and calculated by the following method.
[Method for measuring moisture content]
After weighing the resin composition pellets with an electronic balance (W1: unit g), put them in a hot air oven type dryer maintained at 150 ° C., dry them for 5 hours, and further cool them in a desiccator for 30 minutes. is similarly weighed (W2: unit g), and calculated from the following formula (1).
[Formula 1]
Moisture content (%) = {(W1-W2)/W1} x 100 (1)

Also, the blending can be carried out using known mixing devices such as rocking mixers, ribbon blenders, and line mixers.

<Multilayer structure>
A layer composed of the resin composition of the present invention (hereinafter simply referred to as a "resin composition layer" refers to a layer composed of the resin composition of the present invention) is laminated with another substrate to form a multilayer structure. It is possible to further increase strength and add other functions.

As the substrate, a layer composed of the other thermoplastic resin (C) (hereinafter referred to as "thermoplastic resin (C) layer") is preferably used. A plurality of layers of each of the substrates may be provided as necessary.

As the other thermoplastic resin (C), the same resin as described above can be used.
As the base material, among the other thermoplastic resins (C), polyamide-based resins are preferable in terms of flexibility and stretchability, and when considering hydrophobicity, polyethylene-based resins, which are relatively hydrophobic resins Polyolefin resins such as resins, polypropylene resins, polycyclic olefin resins, and unsaturated carboxylic acid-modified polyolefin resins thereof, polyester resins, and polystyrene resins are preferable, and polyamide resins and polyolefin resins are more preferable. Polyamide-based resins and polycyclic olefin-based resins are particularly preferred. These can be used alone or in combination of two or more.

As the polyamide-based resin, the same one as described above can be used. A terminal-modified polyamide resin is preferred.

When at least one surface of the resin composition layer of the present invention has a polyamide resin layer, there is a tendency to obtain a multilayer structure having excellent flexibility and stretchability.

It is also preferable to use a layer made of an adhesive resin (hereinafter simply referred to as "adhesive resin layer") between the resin composition layer and another thermoplastic resin (C) layer. When a thermoplastic resin layer other than EVOH (A) is provided on at least one side of the resin composition layer of the present invention via an adhesive resin layer, there is a tendency to obtain a multi-layered structure with good water resistance. .
As the adhesive resin, a known one can be used, and it may be appropriately selected according to the type of the other thermoplastic resin (C) layer that serves as the base material. A typical example is a modified polyolefin polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by an addition reaction, a graft reaction, or the like. 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 Modified ethylene-vinyl acetate copolymers, maleic anhydride-modified polycyclic olefin resins, maleic anhydride graft-modified polyolefin resins, etc., may be used alone or in combination of two or more thereof.

In the other thermoplastic resin (C) layer and the adhesive resin layer, a conventionally known plasticizer, It may contain filler, clay (montmorillonite, etc.), colorant, antioxidant, antistatic agent, lubricant, core material, antiblocking agent, ultraviolet absorber, wax, and the like.

The layer structure of the multilayer structure includes α (α1, α2, ...) for the resin composition layer of the present invention, β (β1, β2, ...) for the adhesive resin layer, and another thermoplastic resin (C ) layer is γ (γ1, γ2, ...), α1/β/α2, γ1/β1/α/β2/γ2, γ1/α/γ2, γ/β/α, α1/β/α2 /β/γ, etc. Any combination is possible.
In particular, when a polyamide-based resin is used as the other thermoplastic resin (C) layer, and the polyamide-based resin layer is δ (δ1, δ2, ...), another thermoplastic resin (C) other than the polyamide-based resin Assuming that the layers are γ (γ1, γ2, . β/α2/δ2, δ1/β1/α1/β2/α2/β3/δ2, γ/α/β/δ, δ1/β/α/γ/δ2, δ/α1/β2/α2/γ, δ1/ β1/α/γ/β2/δ2, δ1/β1/γ1/α/γ2/β2/δ2, δ1/α1/β/α2/γ/δ2, δ1/β1/α1/γ1/β2/α2/γ2/ Any combination such as β3/δ2 is possible.

A known method can be used to laminate the resin composition of the present invention on the base material to produce a multilayer structure. For example, a method of melt-extrusion laminating a film, a sheet, or the like of the resin composition of the present invention with another substrate, conversely, a method of melt-extrusion laminating the resin composition of the present invention onto another substrate, or a method of melt-extrusion laminating the resin composition of the present invention. A method of co-extrusion molding a product and another base material, preparing a film (layer) made of the resin composition of the present invention and another base material (layer), and exposing these to an organic titanium compound, an isocyanate compound, a polyester A method of dry laminating using a known adhesive such as a compound or a polyurethane compound, and a method of applying a solution of the resin composition of the present invention onto another base material and then removing the solvent can be mentioned. Among these, the method of co-extrusion molding is preferable from the viewpoint of cost and environment.

The multilayer structure is then subjected to a (heating) stretching treatment, if necessary. The stretching treatment may be either uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, simultaneous stretching or sequential stretching may be used. Moreover, as a stretching method, a roll stretching method, a tenter stretching method, a tubular stretching method, a stretch blowing method, a vacuum pressure forming method, or the like, which has a high stretching ratio, can be used. The stretching temperature is usually selected from the range of 40 to 170°C, preferably 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretching state.

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

Further, when the multi-layer stretched film obtained using the resin composition of the present invention is used as a shrink film, the heat setting is not performed in order to impart heat shrinkability. It may be treated by applying cold air to the surface to cool and fix it.

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 multi-layer container, draw forming is usually employed, and specific examples include vacuum forming, air pressure forming, vacuum pressure forming, and plug-assisted vacuum pressure forming. Furthermore, when a tube or bottle-shaped multi-layer container is obtained from a multi-layer parison (a hollow tubular preform before blowing), a blow molding method is adopted. , parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison blow molding method, injection blow molding method, biaxial stretch blow molding method (extrusion type cold parison biaxial stretch blow molding method, injection type cold parison biaxial stretching blow molding method, injection molding in-line biaxial stretching blow molding method, etc.). If necessary, the multilayer laminate of the present invention is subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making, deep drawing, box processing, tube processing, split processing, and the like. can be done.

The thickness of the multilayer structure (including stretched one) of the present invention, and the thickness of the resin composition layer, polyamide resin layer, adhesive resin layer, and other thermoplastic resin layer constituting the multilayer structure are It is appropriately set according to the constitution, type of thermoplastic resin, type of polyamide resin, type of adhesive resin, application, packaging form, required physical properties, and the like. In the case where there are two or more layers of at least one of the resin composition layer, the adhesive resin layer, and the other thermoplastic resin layer, the numerical values below are the total thicknesses of the layers of the same type. be.

The thickness of the multilayer structure (including stretched one) of the present invention is usually 10 to 5000 μm, preferably 30 to 3000 μm, particularly preferably 50 to 2000 μm. If the total thickness of the multilayer structure is too thin, the gas barrier properties may deteriorate. On the other hand, if the total thickness of the multilayer structure is too thick, the gas barrier properties will be excessive, and unnecessary raw materials will be used, which tends to be uneconomical. The resin composition layer is usually 1-500 μm, preferably 3-300 μm, particularly preferably 5-200 μm, and the other thermoplastic resin layer is usually 5-30000 μm, preferably 10-20000 μm, particularly preferably 20 μm. The thickness of the adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm.

Furthermore, the ratio of the thickness of the resin composition layer to the other thermoplastic resin layer in the multilayer structure (resin composition layer/other thermoplastic resin layer) is the thickness of the thickest layer when there are multiple layers. The ratio is generally 1/99 to 50/50, preferably 5/95 to 45/55, particularly preferably 10/90 to 40/60. In addition, the thickness ratio of the resin composition layer and the polyamide resin layer in the multilayer structure (resin composition layer/polyamide resin layer) is usually 10 at the ratio of the thickest layers when there are multiple layers. /90 to 99/1, preferably 20/80 to 80/20, particularly preferably 40/60 to 60/40. In addition, the thickness ratio of the resin composition layer and the adhesive resin layer (resin composition layer/adhesive resin layer) in the multilayer structure is usually 10 at the ratio of the thickest layers when there are multiple layers. /90 to 99/1, preferably 20/80 to 95/5, particularly preferably 50/50 to 90/10.

Bags made of the films and stretched films obtained as described above, containers and lids made of cups, trays, tubes, bottles, etc., can be used not only for general foods, but also for seasonings such as mayonnaise and dressings, miso and the like. It is useful as a container for various packaging materials such as fermented foods, oily foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

Among them, a multilayer structure having a layer composed of the resin composition of the present invention is improved in the deterioration of color tone during melt molding, and the occurrence of poor appearance, in particular, the decrease in image definition is reduced. This is because fine interface roughness that causes poor appearance is reduced at the lamination interfaces of the resin composition layer/adhesive resin layer and/or the resin composition layer/polyamide resin layer of the multilayer structure. It is considered to be for This includes general foods, seasonings such as mayonnaise and dressings, fermented foods such as miso, oil and fat foods such as salad oil, soups, beverages, cosmetics, pharmaceuticals, detergents, cosmetics, industrial chemicals, pesticides, and fuels. Useful as a container. In particular, mayonnaise, ketchup, sauces, miso, wasabi, mustard, semi-solid foods and seasonings such as yakiniku sauce, salad oil, mirin, sake, beer, wine, juice, black tea, sports drinks, mineral water, milk Bottle-shaped containers and tube-shaped containers for liquid beverages and seasonings such as fruit, jelly, pudding, yogurt, mayonnaise, miso, processed rice, cooked foods, cups for semi-solid foods such as soups and seasonings It is useful as a packaging material for wide-mouthed containers for raw meat, processed meat products (ham, bacon, wieners, etc.), cooked rice, and pet food.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. "Parts" in the examples are based on weight.

[Example 1]
<Production of resin composition>
As EVOH (A), EVOH (a1) [ethylene structural unit content 38 mol%, saponification degree 99.6 mol%, MFR 4.2 g/10 min (210 ° C., load 2160 g) ethylene-vinyl alcohol copolymer Coalescing] As a pellet and a metal salt (B), zinc gluconate trihydrate (b1) was used in an amount of 0.06 part per 100 parts of EVOH (a1). EVOH (a1) pellets and zinc gluconate trihydrate (b1) are blended and dry-blended all at once, and then melt-kneaded and pelletized with a 20 mmφ twin-screw extruder (L/D = 25). A resin composition of the present invention was prepared.

<Manufacturing of multilayer structure>
The resin composition prepared above, linear low-density polyethylene (LLDPE) (“UF240” manufactured by Nippon Polyethylene Co., Ltd., MFR 2.1 g / 10 minutes (190 ° C., load 2160 g)), adhesive resin (“PLEXAR manufactured by LyondellBasell PX3236", MFR 2.0 g / 10 minutes (190 ° C., load 2160 g)) using a three-kind five-layer multi-layer co-extrusion cast film forming apparatus, multi-layer co-extrusion molding is performed under the following conditions, LLDPE layer / adhesion A multilayer structure (film) having a three-kind five-layer structure of adhesive resin layer/EVOH layer/adhesive resin layer/LLDPE layer was obtained. The thickness (μm) of each layer of the multilayer structure was LLDPE layer/adhesive resin layer/EVOH layer/adhesive resin layer/LLDPE layer=37.5/5/15/5/37.5. The die temperature of all molding machines was set at 210°C.

(Multilayer co-extrusion molding conditions)
・ Intermediate layer extruder (EVOH): 40 mmφ single screw extruder (barrel temperature: 210 ° C.)
・ Upper and lower layer extruder (LLDPE): 40 mmφ single screw extruder (barrel temperature: 210 ° C.)
・ Middle and upper layer extruder (adhesive resin): 32 mmφ single screw extruder (barrel temperature: 210 ° C)
・Die: 3 types of 5-layer feed block type T-die (die temperature: 210°C)
・Take-up speed: 14 m/min ・Roll temperature: 50°C

<Image clarity of multilayer structure>
The image clarity of the multilayer structure produced above was evaluated by image definition measurement (optical comb: 0.5 mm) in accordance with JIS K 7374 "Plastics - Determination of image clarity". Film specimens were measured with the film machine direction as the vertical direction. As a measuring instrument, an ICM-1 type image clarity measuring instrument manufactured by Suga Test Instruments Co., Ltd. was used.
This image clarity means that the higher the numerical value, the more excellent the transparency. Table 1 shows the results of evaluation according to the following criteria.
A: The image definition is 80% or more.
◯: Image definition is 70 to 79%.
x: Image definition is less than 70%.

<Appearance of multilayer structure>
The appearance of the multilayer structure produced above was visually evaluated according to the following evaluation criteria.
A: Appearance is very good.
○: Appearance is good.
x: Poor appearance (granular lumps can be confirmed).

[Example 2]
A resin composition and a multilayer structure were produced in the same manner as in Example 1, except that 0.1 part of zinc gluconate trihydrate (b1) was used per 100 parts of EVOH (a1). The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Example 3]
A resin composition and a multilayer structure were prepared in the same manner as in Example 1, except that 0.18 part of zinc gluconate trihydrate (b1) was used per 100 parts of EVOH (a1). The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Example 4]
A resin composition and a multilayer structure were produced in the same manner as in Example 1, except that 1 part of zinc gluconate trihydrate (b1) was used per 100 parts of EVOH (a1). The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[ Reference example 1 ]
In Example 1, calcium gluconate monohydrate (b2) was added to EVOH (a1) 100
A resin composition and a multilayer structure were produced in the same manner except that 0.06 part was used for each part. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[ Reference example 2 ]
In Example 1, magnesium gluconate dihydrate (b3) was converted to EVOH (a1) 10
A resin composition and a multilayer structure were produced in the same manner except that 0.06 part was used with respect to 0 part. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 1]
Example 1 was repeated except that zinc gluconate trihydrate (b1) was not blended and stearic acid was used in an amount of 0.06 parts per 100 parts of EVOH (a1). made the body. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 2]
Example 1 was repeated except that zinc gluconate trihydrate (b1) was not blended and 0.06 parts of calcium stearate was used per 100 parts of EVOH (a1). made the body. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 3]
Example 1 was repeated except that zinc gluconate trihydrate (b1) was not blended and sodium stearate was used in an amount of 0.06 parts per 100 parts of EVOH (a1). A structure was created. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 4]
A resin composition was prepared in the same manner as in Example 1 except that the zinc gluconate trihydrate (b1) was not blended and 0.06 parts of ethylenebisstearic acid amide was used per 100 parts of EVOH (a1). and a multilayer structure. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 5]
In the same manner as in Example 1, except that zinc gluconate trihydrate (b1) was not blended and 0.06 parts of calcium citrate tetrahydrate was used per 100 parts of EVOH (a1), resin Compositions and multilayer structures were made. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 6]
In the same manner as in Example 1, except that zinc gluconate trihydrate (b1) was not blended and 0.06 parts of zinc citrate dihydrate was used per 100 parts of EVOH (a1), resin Compositions and multilayer structures were made. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

[Comparative Example 7]
A resin composition and a multilayer structure were produced in the same manner as in Example 1, except that zinc gluconate trihydrate was not used. The image definition and appearance of the obtained multilayer structure were evaluated in the same manner as in Example 1.

From the above results, Examples 1 to 4 of the multilayer structure produced using the resin composition containing EVOH (A) and the metal salt (B) had high image definition of the multilayer structure and good appearance. It can be seen that it is.

On the other hand, in Comparative Examples 1 to 7 of the multilayer structure produced using the resin composition containing no metal salt (B), the image definition and / or appearance of the multilayer structure is insufficient. I understand.

The present invention is a resin composition containing EVOH (A) and a monocarboxylic acid metal salt (B) having a hydroxyl group and having 2 to 17 carbon atoms, and a multilayer obtained using this resin composition. The structure has a high image definition of the multilayer structure and a good appearance. For this reason, it is useful as a packaging material for various foods, particularly as a container for alcoholic beverages. The multi-layered structure made of the resin composition of the present invention can be used for general foods, seasonings such as mayonnaise and dressings, fermented foods such as miso, oil and fat foods such as salad oil, beverages, cosmetics, and various packaging materials such as pharmaceuticals. It is useful as a raw material for material containers.

Claims (5)

An ethylene-vinyl alcohol-based copolymer (A) and a hydroxy group containing a monovalent aliphatic carboxylic acid metal salt (B) having 2 to 10 carbon atoms, the carboxylic acid metal salt (B) is selected from the 4th period of the d block of the periodic table. 2. The resin composition according to claim 1, wherein the content of the metal salt (B) is 0.01 to 5 parts per 100 parts of the ethylene-vinyl alcohol copolymer (A). 3. The resin composition according to claim 1, wherein said metal salt (B) is a saturated hydrate. A thermoplastic resin other than the ethylene-vinyl alcohol copolymer (A) is applied to at least one surface of the layer comprising the resin composition according to any one of claims 1 to 3 via an adhesive resin layer. A multilayer structure comprising a fat layer. A multilayer structure comprising a layer made of the resin composition according to any one of claims 1 to 3 and a polyamide resin layer on at least one surface thereof.