JP7365972B2 - Resin compositions, molded bodies, multilayer structures, and containers - Google Patents

Description

The present invention relates to a resin composition, a molded article, a multilayer structure, and a container.

In general, ethylene-vinyl alcohol copolymers (hereinafter also referred to as "EVOH") have excellent transparency, gas barrier properties, fragrance retention, solvent resistance, oil resistance, and the like. Taking advantage of these characteristics, EVOH is used in films, sheets, containers, etc., as packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals, and the like. EVOH is also used for applications such as fuel tanks for automobiles and other vehicles, tire tube materials, agricultural films, geomembranes, and shoe cushioning materials due to its barrier properties, heat retention properties, and stain resistance. ing. In particular, a multilayer structure (laminate) having an EVOH layer and another thermoplastic resin layer is known to be useful as a packaging material for boil sterilization or retort sterilization of foods.

EVOH has low thermal stability compared to other resins, and may produce lumps during heat treatment and molding. Furthermore, when EVOH is exposed to light, heat, etc. due to outdoor use, its mechanical strength may decrease. Regarding the thermal stability of EVOH, Patent Document 1 states that it contains ethylene units (III), vinyl alcohol units (IV) and vinyl ester units (V), and the ratio of ethylene units (III) to the total of the above units (III+IV+V). is 20 to 60 mol%, and the ratio of the total (I+II) of carboxylic acid units (I) and lactone ring units (II) at the polymer terminal of the copolymer to the total of the above units (III+IV+V) is 0.12 mol% or less EVOH is described. According to Patent Document 1, EVOH with a small number of terminal carboxylic acid units and lactone ring units is said to be less likely to cause lumps during heat treatment and molding, and to improve long-run performance during melt molding.

In addition, when packaging materials containing EVOH are heat-treated with hot water or steam for a long period of time, whitening streaks, partial clouding (whitening, etc.), delamination (hereinafter sometimes abbreviated as "delami"), etc. may occur. , the appearance may deteriorate. Patent Document 2 discloses that EVOH, a polyamide resin (hereinafter sometimes abbreviated as "PA"), and a magnesium salt of a fatty acid having 6 or less carbon atoms are contained in a specific amount, and both EVOH and PA contain 6 carbon atoms. A resin composition pellet in which the following fatty acid magnesium salt is dispersed is described. A film using the resin composition pellets is said to have excellent thermal stability during film formation and excellent appearance after heat treatment.

International Publication No. 2004/092234 International Publication No. 2015/174396

However, the EVOH of Patent Document 1 has a total ratio (I+II) of carboxylic acid units (I) and lactone ring units (II) of 0.12 mol% or less, and EVOH with a high total ratio It has not been possible to improve the stability, that is, to suppress the bumps that occur during heat treatment and molding. Further, the EVOH of Patent Document 1 does not take into consideration heat resistance and light resistance in consideration of long-term outdoor use. Furthermore, in recent years, discarded plastic products are flowing into the ocean, turning into microplastics and polluting the ocean, which has become a problem. For this reason, there is a need to develop resins that are difficult to turn into microplastics. In particular, as shown in Table 11 (Reference Comparative Examples 18 to 20) of Examples described below, the sum of carboxylic acid units (I) and lactone ring units (II) such as EVOH of Patent Document 1 The inventors have found that materials with a low ratio of (I+II) are more likely to become microplastics.

On the other hand, the characteristics of EVOH such as thermal stability, heat resistance and light resistance are influenced by the structure of EVOH itself such as ethylene content. Therefore, it is possible to some extent to improve thermal stability, heat resistance, light resistance, etc. by adjusting the ethylene content and the like. However, since EVOH having a suitable ethylene content etc. depending on the purpose of the molded article is usually used, it is possible to improve various properties such as thermal stability, heat resistance and light resistance without changing the EVOH itself. is desired. In addition, there is a need for an EVOH resin composition that can be molded into a molded article or the like in which appearance defects are suppressed after heat treatment with hot water or steam such as retort treatment.

The present invention was made based on the above-mentioned circumstances, and its purpose is to provide a molded article that suppresses the occurrence of lumps during melt molding, has sufficient heat and light resistance, and is difficult to turn into microplastics after disposal. It is a resin composition that can be obtained, and the above characteristics are sufficiently improved compared to those using the same EVOH, and the occurrence of appearance defects after heat treatment with hot water or steam such as retort treatment is suppressed. It is an object of the present invention to provide a resin composition that can be molded into a molded object, etc., as well as a molded object, a multilayer structure, and a container using this resin composition.

According to the invention, the above objectives are:
[1] Resin containing ethylene-vinyl alcohol copolymer (A), aluminum ion (B), polyamide (D), and at least one metal atom (E) selected from the group consisting of magnesium, calcium, and zinc A composition in which at least a part of the ethylene-vinyl alcohol copolymer (A) has at least one of a carboxylic acid unit (I) and a lactone ring unit (II) located at the terminal of the polymer, and The total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of vinyl alcohol copolymer (A) is 14 μmol/g or more and 78 μmol/g or less, and the ethylene-vinyl alcohol copolymer (A) The content (b) of aluminum ions (B) per 1 g is 0.002 μmol/g or more and 0.17 μmol/g or less, and the mass of the polyamide (D) relative to the ethylene-vinyl alcohol copolymer (A) The ratio (D/A) is 5/95 or more and 40/60 or less, and the content (e) of the metal atom (E) in the ethylene-vinyl alcohol copolymer (A) is 1 ppm or more and 500 ppm or less in terms of metal element. A resin composition;
[2] The ratio ((i+ii)/b) of the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) to the content (b) of aluminum ions (B) is 180 or more and 20 ,000 or less, the resin composition of [1];
[3] The resin composition of [1] or [2], in which the aluminum ion (B) is derived from a fatty acid aluminum salt having 5 or less carbon atoms;
[4] Further contains at least one compound (C) selected from the group consisting of cinnamic acids and conjugated polyene compounds with a molecular weight of 1,000 or less, and the content of the compound (C) in the ethylene-vinyl alcohol copolymer (A). The resin composition according to any one of [1] to [3], wherein the amount (c) is 1 ppm or more and 1,000 ppm or less;
[5] The ratio (ii/(i+ii)) of the content (ii) of the lactone ring unit (II) to the total content (i+ii) of the carboxylic acid unit (I) and the lactone ring unit (II) is 40 mol% or more. The resin composition according to any one of [1] to [4];
[6] A molded article formed from the resin composition of any one of [1] to [5];
[7] A multilayer structure including a layer made of the resin composition according to any one of [1] to [5];
[8] A container made of the multilayer structure of [7];
[9] The container of [8] for boil sterilization or retort sterilization;
This is achieved by providing one of the following:

According to the present invention, it is a resin composition that suppresses the occurrence of lumps during melt molding, has sufficient heat resistance and light resistance, and provides molded products that are difficult to turn into microplastics after disposal, and is similar to those using the same EVOH. A resin composition which can be molded into a molded article, etc., which has sufficiently improved each of the above characteristics in comparison, and which has suppressed the occurrence of appearance defects after heat treatment with hot water or steam such as retort treatment, and this resin composition. Molded objects, multilayer structures, and containers using the resin composition can be provided.

Solvent: DMSO-d ₆ Measurement temperature: ¹ H-NMR spectrum of EVOH-A of Synthesis Example 1 measured at 25°C. Solvent: DMSO-d ₆ Measurement temperature: ¹ H-NMR spectrum of EVOH-A of Synthesis Example 1 measured at 80°C. Solvent: D ₂ O + MeOD Measurement temperature: ¹ H-NMR spectrum of EVOH-A of Synthesis Example 1 measured at 80°C.

<Resin composition>
The resin composition of the present invention comprises an ethylene-vinyl alcohol copolymer (A) (hereinafter sometimes referred to as "EVOH (A)"), an aluminum ion (B), a polyamide (D), and magnesium and calcium. and at least one metal atom (E) selected from the group consisting of zinc. At least a portion of EVOH (A) has at least one of a carboxylic acid unit (I) and a lactone ring unit (II) located at the polymer terminal. The total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of EVOH (A) is 14 μmol/g or more and 78 μmol/g or less. The content (b) of aluminum ions (B) per 1 g of EVOH (A) is 0.002 μmol/g or more and 0.17 μmol/g or less. The mass ratio (D/A) of the polyamide (D) to the ethylene-vinyl alcohol copolymer (A) is 5/95 or more and 40/60 or less, and the ethylene-vinyl alcohol copolymer (A) of the metal atom (E) is ) is 1 ppm or more and 500 ppm or less in terms of metal element.

The resin composition of the present invention is a resin composition that suppresses the occurrence of lumps during melt molding, has sufficient heat resistance and light resistance, and can obtain a molded product that is difficult to turn into microplastics after disposal, and is a resin composition that can be obtained using the same EVOH. Each of the above characteristics has been sufficiently improved compared to the original. Therefore, according to the resin composition of the present invention, the generation of lumps can be further suppressed without changing the type of EVOH, and the heat resistance and light resistance and resistance to microplasticization of the obtained molded product etc. can be improved. The reason why such an effect occurs is not clear, but it is assumed to be as follows. A stable structure is formed by a predetermined amount of aluminum ion (B) interacting with the carboxylic acid unit (I) and lactone ring unit (II) located at the terminal of EVOH (A). This suppresses gelation during melt molding, thereby suppressing the occurrence of lumps. It is also presumed that the resulting molded product has excellent heat and light resistance and is difficult to turn into microplastic after disposal, as a result of the above-mentioned stable structure being formed.

Furthermore, the resin composition of the present invention further contains polyamide (D) and at least one metal atom (E) selected from the group consisting of magnesium, calcium, and zinc, and the content thereof is higher than that of EVOH (A). By being within a predetermined range, it is possible to mold a molded object, etc. that suppresses the occurrence of appearance defects after heat treatment with hot water or steam such as retort treatment while suppressing the occurrence of lumps during melt molding. I can do it.

The resin composition of the present invention preferably further contains at least one compound (C) selected from the group consisting of cinnamic acids and conjugated polyene compounds having a molecular weight of 1,000 or less. Moreover, the resin composition of the present invention may further contain components other than EVOH (A), aluminum ion (B), compound (C), polyamide (D), and metal atom (E). Each component of the resin composition of the present invention will be explained in detail below.

(EVOH(A))
EVOH (A) is a copolymer having ethylene units and vinyl alcohol units. EVOH (A) is usually obtained by a saponification reaction of an ethylene-vinyl ester copolymer. Therefore, EVOH (A) may further have residual vinyl ester units. That is, EVOH (A) is a copolymer having an ethylene unit and a vinyl alcohol unit, and further having or not having a vinyl ester unit as an arbitrary monomer unit. The production and saponification of the ethylene-vinyl ester copolymer can be carried out by known methods. Vinyl acetate is a typical vinyl ester, but other fatty acid vinyls such as vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, and vinyl versatate can also be used. It may also be an ester.

At least a portion of EVOH (A) has at least one of a carboxylic acid unit (I) and a lactone ring unit (II) located at the polymer terminal (main chain terminal). The carboxylic acid unit (I) is a structural unit located at the end of a polymer and has a carboxy group. The carboxylic acid unit (I) is also referred to as a terminal carboxylic acid unit. A part or all of the carboxy group possessed by the carboxylic acid unit (I) may exist in the form of a salt or an anion (-COO ^- ). The lactone ring unit (II) is a structural unit located at the end of the polymer and has a lactone ring. The lactone ring unit (II) is also referred to as a terminal lactone ring unit. The number of members of the lactone ring is not particularly limited, and may be, for example, a 4- to 6-membered ring, with a 5-membered ring being preferred. The carboxylic acid unit (I) may be, for example, a structural unit represented by the following formula (1). The lactone ring unit (II) may be a structural unit represented by the following formula (2), for example.

In formula (1), X is a hydrogen atom, a hydroxy group, or an esterified hydroxy group. Y is a hydrogen atom or a metal atom.

Examples of the esterified hydroxy group represented by X include -OCO-CH ₃ and -OCO-C ₂ H ₅ .

Examples of the metal atom represented by Y include alkali metals such as sodium, alkaline earth metals such as magnesium and calcium, typical metals such as aluminum, transition metals, and the like. Among these, typical elements are preferred, and alkali metals, alkaline earth metals, and aluminum are preferred. When Y is aluminum, this aluminum is included in the aluminum ion (B). When Y is a divalent or higher metal atom, two or more carboxylate anions (-COO ^- ) may be bonded or coordinated to one Y.

The total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of EVOH (A), that is, the carboxylic acid units (I) and lactone ring units (II) present in 1 g of EVOH (A). ) The lower limit of the total amount (substance amount: number of moles) is 14 μmol/g, preferably 18 μmol/g, and more preferably 22 μmol/g. Further, the lower limit of the total content of carboxylic acid units (I) and lactone ring units (II) with respect to the total content of ethylene units, vinyl alcohol units, and vinyl ester units of EVOH (A) is preferably 0.10 mol%, 0.12 mol% is more preferable, and 0.14 mol% is even more preferable. When the total content of carboxylic acid units (I) and lactone ring units (II) is at least the above-mentioned lower limit, interaction with aluminum ions (B) will occur sufficiently, particularly improving microplasticization resistance.

On the other hand, the upper limit of the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of EVOH (A) is 78 μmol/g, preferably 70 μmol/g, and 60 μmol/g. More preferably, 50 μmol/g is even more preferred, and particularly preferably 40 μmol/g. Further, the upper limit of the total content of carboxylic acid units (I) and lactone ring units (II) with respect to the total content of ethylene units, vinyl alcohol units, and vinyl ester units of EVOH (A) is preferably 0.4 mol%, 0.3 mol% is more preferable, and 0.25 mol% is even more preferable. When there are too many carboxylic acid units (I) and lactone ring units (II), thermal stability decreases. Specifically, the carboxylic acid unit (I) and the lactone ring unit (II) can react with the hydroxy group of EVOH (A) at high temperatures to form a highly polymerized polymer having branches. Therefore, when the content of carboxylic acid units (I) and lactone ring units (II) is large, there is a tendency to reduce the melt moldability of EVOH (A). Therefore, when the total content of carboxylic acid units (I) and lactone ring units (II) is below the above upper limit, the generation of lumps during melt molding can be suppressed.

Ratio (ii/(i+ii)) of content (ii) of lactone ring unit (II) to total content (i+ii) of carboxylic acid unit (I) and lactone ring unit (II) of EVOH (A): lactone ring unit The lower limit of the ratio) may be, for example, 30 mol%, preferably 40 mol%, and more preferably 50 mol%. When the lactone ring unit ratio (ii/(i+ii)) is equal to or higher than the above lower limit, heat resistance and light resistance and microplasticization resistance tend to increase due to effective interaction with aluminum ions (B), etc. be. On the other hand, the upper limit of this lactone ring unit ratio (ii/(i+ii)) may be, for example, 90 mol%, 80 mol%, or 70 mol%.

The total content (i + ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of EVOH (A) is adjusted by, for example, polymerization conditions such as the type of polymerization initiator, drying conditions such as drying atmosphere, etc. Ru. In EVOH (A) which does not have a branched structure, the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) tends to be relatively small when the degree of polymerization is high. In many cases, it does not follow the trend. For example, as described in Patent Document 1, the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) can be reduced by contacting an ethylene-vinyl ester copolymer or EVOH with a reducing agent. can be reduced. Conversely, the total content of carboxylic acid units (I) and lactone ring units (II) can be reduced by contacting the ethylene-vinyl ester copolymer or EVOH with an oxidizing agent or by drying it in an atmosphere that easily oxidizes. It is also possible to increase the amount (i+ii). Furthermore, the ratio of the content (ii) of the lactone ring unit (II) to the total content (i+ii) of the carboxylic acid units (I) and the lactone ring unit (II) (ii/(i+ii): lactone ring unit ratio) is , can be adjusted by saponification conditions, etc. For example, if saponification is performed under conditions that promote saponification, the lactone ring unit ratio (ii/(i+ii)) tends to increase.

The total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) located at the polymer terminal of EVOH (A) and the lactone ring unit ratio (ii/(i+ii)) are determined by ¹ H-NMR measurement. is required. The inventors have found that the above measurement results differ depending on the type of solvent used during the measurement. Therefore, the above measurement is performed using a mixed solvent of water/methanol (mass ratio 4/6, however, if the sample does not dissolve, the mass ratio is changed as appropriate). Specifically, the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) and the lactone ring unit ratio (ii/(i+ii)) were measured by the method described in the Examples below. value.

The lower limit of the content of ethylene units in EVOH (A) is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and even more preferably 25 mol%. On the other hand, the upper limit of the content of ethylene units in EVOH (A) is preferably 60 mol%, more preferably 55 mol%, and even more preferably 50 mol% or 45 mol%. By setting the content of ethylene units to the above lower limit or more, thermal stability, microplasticization resistance, etc. tend to improve. Further, by controlling the content of ethylene units to be below the above-mentioned lower limit, oxygen barrier properties and the like tend to improve.

The lower limit of the degree of saponification of EVOH (A) is preferably 90 mol%, more preferably 95 mol%, even more preferably 99 mol%, and particularly preferably 99.6 mol%. By setting the degree of saponification of EVOH (A) to the above-mentioned lower limit or more, melt moldability, gas barrier properties, heat resistance, light resistance, moisture resistance, etc. of the obtained molded product tend to be improved. Moreover, the degree of saponification may be 100 mol% or less, 99.97 mol% or less, or 99.94 mol% or less.

EVOH (A) contains carboxylic acid units (I), lactone ring units (II), and units derived from other monomers other than ethylene, vinyl ester, and saponified products thereof, to the extent that the effects of the present invention are not impaired. may have. The content of units derived from other monomers (units other than carboxylic acid units (I), lactone ring units (II), ethylene units, vinyl ester units, and vinyl alcohol units) with respect to the total structural units of EVOH (A) is It is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, even more preferably 5 mol% or less, and particularly preferably 1 mol% or less. Moreover, when EVOH (A) has units derived from the other monomers mentioned above, the content thereof may be 0.05 mol% or more, or 0.1 mol% or more.

Examples of other monomers include unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid, or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; acrylamide and methacryl Amides such as amides; Olefin sulfonic acids or their salts such as vinyl sulfonic acid, allyl sulfonic acid, meta-allylsulfonic acid; vinyl trimethoxysilane, vinyl triethoxy silane, vinyl tri(β-methoxy-ethoxy) silane, γ-methacryloxy Vinyl silane compounds such as propylmethoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like.

In addition, units derived from other monomers include a structural unit (X) represented by the following formula (I), a structural unit (Y) represented by the following formula (II), and a structural unit (Y) represented by the following formula (III). The structural unit (Z) may be at least one type of structural unit (Z).

In the above formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are each independently a hydrogen atom and have 1 to 10 carbon atoms. represents an aliphatic hydrocarbon group, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, or a hydroxyl group. One pair of R ¹ , R ² and R ³ , R ⁴ and R ⁵ , and R ⁶ and R ⁷ may be bonded (provided that one pair of R ¹ , R ² and R ³ are both hydrogen atoms). (excluding cases where R ⁴ and R ⁵ or R ⁶ and R ⁷ are both hydrogen atoms). In addition, some or all of the hydrogen atoms possessed by the aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms, and the aromatic hydrocarbon group having 6 to 10 carbon atoms are It may be substituted with a hydroxyl group, an alkoxy group, a carboxyl group, or a halogen atom. In the above formula, R ¹² and R ¹³ each independently represent a hydrogen atom, a formyl group, or an alkanoyl group having 2 to 10 carbon atoms.

When EVOH (A) has a structural unit (X), (Y) or (Z), the flexibility and processing properties of the resin composition are improved, and the stretchability and thermoformability of the resulting molded article or multilayer structure are improved. etc. tend to be better.

In the structural unit (X), (Y) or (Z), examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include an alkyl group and an alkenyl group. Examples of the alicyclic hydrocarbon group having 3 to 10 carbon atoms include a cycloalkyl group and a cycloalkenyl group. Examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include phenyl group.

In the structural unit (X), R ¹ , R ² and R ³ are each independently preferably a hydrogen atom, a methyl group, an ethyl group, a hydroxyl group, a hydroxymethyl group, and a hydroxyethyl group, and among them, the resulting multilayer structure, etc. From the viewpoint of further improving the stretchability and thermoformability in , a hydrogen atom, a methyl group, a hydroxyl group, and a hydroxymethyl group are each independently more preferable.

The method for incorporating the structural unit (X) into EVOH (A) is not particularly limited, and for example, in the polymerization of ethylene and vinyl ester, a method of copolymerizing a monomer derived from the structural unit (X), etc. Can be mentioned. Examples of monomers derived from the structural unit (X) include alkenes such as propylene, butylene, pentene, and hexene; 3-hydroxy-1-propene, 3-acyloxy-1-propene, and 3-acyloxy-1-butene; , 3-hydroxy-1-butene, 4-hydroxy-1-butene, 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-hydroxy-1-butene, 4-acyloxy -3-hydroxy-1-butene, 3-acyloxy-4-methyl-1-butene, 4-acyloxy-2-methyl-1-butene, 4-acyloxy-3-methyl-1-butene, 3,4-diacyloxy -2-methyl-1-butene, 4-hydroxy-1-pentene, 5-hydroxy-1-pentene, 4,5-dihydroxy-1-pentene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene , 4,5-diasiloxy-1-pentene, 4-hydroxy-3-methyl-1-pentene, 5-hydroxy-3-methyl-1-pentene, 4,5-dihydroxy-3-methyl-1-pentene, 5 , 6-dihydroxy-1-hexene, 4-hydroxy-1-hexene, 5-hydroxy-1-hexene, 6-hydroxy-1-hexene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6 Examples include alkenes having a hydroxyl group or an ester group, such as -acyloxy-1-hexene and 5,6-diacyloxy-1-hexene. Among them, propylene, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1 are preferred from the viewpoint of copolymerization reactivity, processability and gas barrier properties of the obtained molded bodies and multilayer structures. -butene and 3,4-diacyloxy-1-butene are preferred. Note that "acyloxy" is preferably acetoxy, and specifically 3-acetoxy-1-propene, 3-acetoxy-1-butene, 4-acetoxy-1-butene and 3,4-diacetoxy-1-butene are preferred. In the case of an alkene having an ester, it is induced into the structural unit (X) during the saponification reaction.

In the structural unit (Y), both R ⁴ and R ⁵ are preferably hydrogen atoms. In particular, it is more preferable that R ⁴ and R ⁵ are both hydrogen atoms, one of R ⁶ and R ⁷ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and the other is a hydrogen atom. As the aliphatic hydrocarbon group, an alkyl group and an alkenyl group are preferred. From the viewpoint of placing particular importance on the gas barrier properties of the obtained molded article and multilayer structure, it is more preferable that one of R ⁶ and R ⁷ is a methyl group or an ethyl group, and the other is a hydrogen atom. Further, it is more preferable that one of R ⁶ and R ⁷ is a substituent represented by (CH ₂ ) _h OH (where h is an integer of 1 to 8), and the other is a hydrogen atom. Note that h is preferably an integer of 1 to 4, more preferably 1 or 2, and even more preferably 1.

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

In the above formula, R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ each independently represent a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms (alkyl group, alkenyl group, etc.), or 3 carbon atoms. Represents an alicyclic hydrocarbon group having ~10 carbon atoms (cycloalkyl group, cycloalkenyl group, etc.) or an aliphatic hydrocarbon group having 6 to 10 carbon atoms (phenyl group, etc.). Further, i, j, k, p and q each independently represent an integer of 1 to 8. However, when R ¹⁷ is a hydrogen atom, R ¹⁸ has a substituent other than a hydrogen atom.

Examples of the monovalent epoxy compound represented by formula (IV) include epoxyethane (ethylene oxide), epoxypropane, 1,2-epoxybutane, 2,3-epoxybutane, 3-methyl-1,2-epoxybutane , 1,2-epoxypentane, 3-methyl-1,2-epoxypentane, 1,2-epoxyhexane, 2,3-epoxyhexane, 3,4-epoxyhexane, 3-methyl-1,2-epoxyhexane , 3-methyl-1,2-epoxyheptane, 4-methyl-1,2-epoxyheptane, 1,2-epoxyoctane, 2,3-epoxyoctane, 1,2-epoxynonane, 2,3-epoxynonane , 1,2-epoxydecane, 1,2-epoxydodecane, epoxyethylbenzene, 1-phenyl-1,2-epoxypropane, 3-phenyl-1,2-epoxypropane and the like. Examples of the monovalent epoxy compound represented by formula (V) include various alkyl glycidyl ethers. Examples of the monovalent epoxy compound represented by formula (VI) include various alkylene glycol monoglycidyl ethers. Examples of the monovalent epoxy compound represented by formula (VII) include various alkenyl glycidyl ethers. Examples of the monovalent epoxy compound represented by formula (VIII) include various epoxy alkanols such as glycidol. Examples of the monovalent epoxy compound represented by formula (IX) include various epoxycycloalkanes. Examples of the monovalent epoxy compound represented by formula (X) include various epoxycycloalkenes.

Among monovalent epoxy compounds, epoxy compounds having 2 to 8 carbon atoms are preferred. In particular, from the viewpoint of ease of handling and reactivity, the monovalent epoxy compound preferably has 2 to 6 carbon atoms, and even more preferably 2 to 4 carbon atoms. Furthermore, the monovalent epoxy compound is particularly preferably a compound represented by formula (IV) or formula (V). Specifically, from the viewpoint of reactivity with EVOH (A), processability of the obtained multilayer structure and thermoformed product, gas barrier properties, etc., 1,2-epoxybutane, 2,3-epoxybutane, epoxy Propane, epoxyethane or glycidol are preferred, with epoxypropane or glycidol being more preferred.

In the structural unit (Z), R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are preferably hydrogen atoms or aliphatic hydrocarbon groups having 1 to 5 carbon atoms, such as methyl group, ethyl group, n-propyl group, isopropyl group, Preferred are n-butyl, isobutyl, tert-butyl or n-pentyl.

The method for incorporating the structural unit (Z) into EVOH (A) is not particularly limited, and examples thereof include the method described in JP-A No. 2014-034647.

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

The lower limit of the content of EVOH (A) in the resin composition of the present invention may be, for example, 50% by mass, preferably 60% by mass, more preferably 70% by mass, and even more preferably 80% by mass. On the other hand, the upper limit of the content of EVOH (A) may be, for example, 95% by mass. Note that the content of EVOH (A) refers to the content (content ratio) in the resin composition in a dry state. Hereinafter, the same applies to the content based on the resin composition.

When the resin composition of the present invention contains two or more types of EVOH (A), flexibility, secondary processability, heat stretchability, etc. tend to be improved while maintaining gas barrier properties.

When using two or more types of EVOH (A) in combination, EVOH (A1) with an ethylene unit content of 20 mol% or more and 50 mol% or less, and EVOH (A2) with an ethylene unit content of 30 mol% or more and 60 mol% or less. , the value obtained by subtracting the ethylene unit content of EVOH (A1) from the ethylene unit content of EVOH (A2) is 5 mol% or more, and the mass ratio (A1/A2) of EVOH (A1) to EVOH (A2) is 60 It is preferable that it is /40 or more and 95/5 or less.

The lower limit of the ethylene content of EVOH (A1) is usually 20 mol%, preferably 23 mol%, and more preferably 25 mol%. On the other hand, the upper limit of the ethylene content of EVOH (A1) is usually 50 mol%, preferably 47 mol%. By setting the ethylene content of EVOH (A1) to the above-mentioned lower limit or more, the effects of flexibility, secondary processability, heat stretchability, etc. of the resin composition are more fully exhibited. On the other hand, by making the ethylene content of EVOH (A1) below the above upper limit, the gas barrier properties of the resin composition can be further improved.

The lower limit of the ethylene content of EVOH (A2) is usually 30 mol%, preferably 34 mol%, and more preferably 38 mol%. On the other hand, the upper limit of the ethylene content of EVOH (A2) is usually 60 mol%, preferably 55 mol%, and more preferably 52 mol%. By setting the ethylene content of EVOH (A2) to the above-mentioned lower limit or more, effects such as flexibility, secondary processability, heat stretchability, etc. of the resin composition are more fully exhibited. On the other hand, by making the ethylene content of EVOH (A2) below the above upper limit, the gas barrier properties of the resin composition can be further improved.

The lower limit of the value obtained by subtracting the ethylene unit content of EVOH (A1) from the ethylene unit content of EVOH (A2) is preferably 5 mol%, more preferably 8 mol%, even more preferably 12 mol%, and particularly preferably 15 mol%. , 18 mol% is most preferred. Further, the upper limit of the above value is preferably 40 mol%, more preferably 30 mol%, and even more preferably 20 mol%. By setting the difference in ethylene content between EVOH (A2) and EVOH (A1) to the above lower limit or more, the heat stretchability of the resin composition can be improved. On the contrary, by making the above-mentioned ethylene content difference below the above-mentioned upper limit, the gas barrier properties of the resin composition can be further improved.

The lower limit of the mass ratio (A1/A2) of EVOH (A1) to EVOH (A2) is preferably 60/40, more preferably 62/38, and 65/35, 68/32, 70/30 or 85/15. In some cases, it may be even more preferable. The upper limit of the mass ratio is preferably 95/5, more preferably 93/7, even more preferably 92/8, even more preferably 91/9, and even more preferably 85/15. When the mass ratio is within the above range, the resin composition has excellent flexibility, heat stretchability, and secondary processability while maintaining gas barrier properties against various gases. For example, by setting the mass ratio (A1/A2) to the lower limit or more, the gas barrier properties and oil resistance of the resin composition can be further improved. On the other hand, by setting the mass ratio (A1/A2) to be equal to or less than the upper limit, the flexibility, heat stretchability, and secondary processability of the resin composition can be improved.

The lower limit of the difference between the melting points of EVOH (A1) and EVOH (A2) is preferably 12°C, more preferably 14°C, even more preferably 15°C, and particularly preferably 17°C. The upper limit of the difference between the melting points of EVOH (A1) and EVOH (A2) may be, for example, 100°C, but preferably 80°C, more preferably 40°C, even more preferably 34°C, and even more preferably 28°C. is particularly preferred. By setting the difference in melting point to the lower limit or more, the heat stretchability of the resin composition can be improved. On the other hand, by setting the difference in melting point to be below the upper limit, the effect of suppressing flow marks during long runs (long-term continuous operation) of the resin composition can be enhanced.

The lower limit of the total content of EVOH (A1) and EVOH (A2) in the resin composition is preferably 80% by mass, more preferably 90% by mass, even more preferably 95% by mass, and especially 99.9% by mass. In some cases it may be preferable.

The lower limit of the content of EVOH (A2) in the resin component of the resin composition is preferably 4% by mass, more preferably 6% by mass, and even more preferably 7% by mass. On the other hand, the upper limit of the content of EVOH (A2) is preferably 40% by mass, more preferably 35% by mass, even more preferably 30% by mass, and particularly preferably 15% by mass. By setting the content of EVOH (A2) to the above lower limit or more, the flexibility, heat stretchability, and secondary processability of the resin composition can be improved. Conversely, by setting the content of EVOH (A2) below the above upper limit, the content of EVOH (A1) can be increased and the gas barrier properties and oil resistance of the resin composition can be improved.

EVOH (A2) may be a modified ethylene-vinyl alcohol copolymer (hereinafter also referred to as "modified EVOH") from the viewpoint of improving the flexibility, secondary processing characteristics, and heat stretchability of the resin composition. Examples of the modified EVOH include the above-described EVOH having the carboxylic acid unit (I), the lactone ring unit (II), and units derived from other monomers other than ethylene, vinyl ester, and saponified products thereof.

(Aluminum ion (B))
The aluminum ion (B) contained in the resin composition of the present invention may exist in a state dissociated from an anion, or may exist in a salt state combined with an anion. Further, it may exist in a coordinated state with a group (for example, a carboxy group, a hydroxyl group, etc.) possessed by EVOH (A) or other optional components.

The aluminum ion (B) is usually derived from a salt, but preferably derived from a fatty acid aluminum salt having 5 or less carbon atoms. That is, when preparing the resin composition of the present invention, it is preferable to use a fatty acid aluminum salt having 5 or less carbon atoms. In other words, in the resin composition of the present invention, it is preferable that a fatty acid aluminum salt having 5 or less carbon atoms is added or contained as a component constituting the aluminum ion (B). Aluminum salts of fatty acids having 5 or less carbon atoms have relatively high solubility in water. Therefore, even if a fatty acid aluminum salt having a carbon number of 5 or less is added in the manufacturing process, precipitation is unlikely to occur, and a resin composition or molded article with excellent appearance and less foreign matter can be obtained. The added fatty acid aluminum salt having 5 or less carbon atoms may be present in the resin composition in the form of a salt in which the aluminum ion (B) and the fatty acid anion remain bonded, and the aluminum ion (B) and the fatty acid anion may be present in the resin composition. The anion may be present in the resin composition in a dissociated state.

Examples of fatty acid aluminum salts having 5 or less carbon atoms include aluminum formate (aluminum triformate, etc.), aluminum acetate, aluminum propionate (aluminum tripropionate, etc.), aluminum butyrate (aluminum tributyrate, etc.), and the like. Among these, it is preferable to use at least one of aluminum acetate and aluminum tripropionate. Here, aluminum acetate is a general term for substances having the structure of aluminum salts of acetic acid, such as basic aluminum acetate and aluminum triacetate. From the viewpoint of solubility in the solvent, one or more of these may be used as appropriate.

In addition, fatty acid aluminum salts having 6 or more carbon atoms, aluminum salts other than fatty acid aluminum salts (aluminum nitrate, aluminum sulfate, etc.), etc. can also be used.

In the resin composition of the present invention, the content (b) of aluminum ions (B) per 1 g of EVOH (A), that is, the content of aluminum ions (B) based on the content (mass) of EVOH (A). The lower limit (amount of substance: number of moles) is 0.002 μmol/g, preferably 0.005 μmol/g, and more preferably 0.01 μmol/g or 0.015 μmol/g. On the other hand, the upper limit of the content (b) is 0.17 μmol/g, preferably 0.15 μmol/g, more preferably 0.10 μmol/g, and even more preferably 0.05 μmol/g or 0.03 μmol/g. In some cases it may be preferable. By setting the content (b) of aluminum ions (B) per 1 g of EVOH (A) within the above range, generation of lumps can be suppressed, heat resistance and light resistance, and resistance to formation of microplastics can be sufficiently improved. In particular, by setting this content (b) within a relatively large range, heat resistance and light resistance and resistance to forming microplastics tend to be greatly improved. On the other hand, by setting this content (b) within a relatively small range, the effect of suppressing the generation of lumps tends to be enhanced.

The ratio of the total content (i + ii) of carboxylic acid units (I) and lactone ring units (II) located at the polymer terminal of EVOH (A) and the content (b) of aluminum ions (B) ((i + ii) The lower limit of /b) is preferably 180, more preferably 300, and even more preferably 1,000. On the other hand, the upper limit of this ratio ((i+ii)/b) is preferably 20,000, more preferably 15,000, and may even more preferably be 10,000, 8,000, 6,000, or 4,000. . By setting the ratio ((i+ii)/b) within the above range, it is possible to more sufficiently improve the suppression of generation of lumps, heat resistance and light resistance, and resistance to formation of microplastics. In particular, by setting this ratio ((i+ii)/b) to a relatively high range, excess aluminum ions (B) that do not contribute to the interaction with EVOH (A) are reduced, which has the effect of suppressing the generation of lumps. is on the rise. On the other hand, by setting the ratio ((i+ii)/b) to a relatively low range, heat resistance and light resistance and resistance to forming microplastics tend to be further improved.

The lower limit of the content of aluminum ions (B) in the resin composition of the present invention may be, for example, 0.01 ppm, preferably 0.05 ppm, and more preferably 0.1 ppm. The effect of the present invention can be further enhanced by setting the content of aluminum ions (B) in the entire resin composition to the above lower limit or more. On the other hand, the upper limit of this content is preferably 4 ppm, more preferably 3 ppm, and even more preferably 2 ppm or 1 ppm. By controlling the content of aluminum ions (B) in the entire resin composition to be below the above upper limit, it is possible to suppress the generation of lumps due to excessive aluminum ions (B).
In addition, in this specification, "ppm" indicates content (content ratio) on a mass basis.

(Compound (C))
It is preferable that the resin composition of the present invention further contains compound (C). Compound (C) is at least one selected from the group consisting of cinnamic acids and conjugated polyene compounds. When the resin composition further contains such a compound (C), it is possible to further improve the suppression of generation of lumps, heat resistance and light resistance, and resistance to formation of microplastics. Although the reason for this is not clear, it is presumed that heat resistance and light resistance are improved by the aluminum ion (B) further interacting with the compound (C).

Cinnamic acids include cinnamic acid (cis-cinnamic acid, trans-cinnamic acid, or mixtures thereof) and cinnamic acid derivatives such as cinnamic acid esters and cinnamic acid salts. The cinnamic acid derivative refers to a compound etc. obtained by reacting cinnamic acid. Examples of cinnamic acid esters include methyl cinnamate, ethyl cinnamate, and the like. Examples of the cinnamate include sodium cinnamate, magnesium cinnamate, calcium cinnamate, and the like. Among these, it is preferable to use cinnamic acid as the cinnamic acid, particularly trans-cinnamic acid from the viewpoints of stability and cost. In addition, when cinnamic acid is used, part or all of the cinnamic acid may become a cinnamic acid salt due to coexistence with aluminum ions (B).

Conjugated polyene compounds have a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately connected, and the number of carbon-carbon double bonds is 2 or more, so-called conjugated double bonds. It is a compound. This conjugated polyene compound may be a conjugated diene having two conjugated double bonds, a conjugated triene having three conjugated double bonds, or a conjugated polyene having more than that number. Moreover, the above-mentioned conjugated double bonds may not be conjugated with each other but may exist in one molecule. For example, compounds having three conjugated triene structures in the same molecule, such as tung oil, are also included in the above conjugated polyene compounds.

The number of conjugated double bonds in the conjugated polyene compound is preferably 7 or less. Coloring can be reduced by using a conjugated polyene compound having 7 or less conjugated double bonds.

In addition to conjugated double bonds, conjugated polyene compounds contain carboxy groups and their salts, hydroxyl groups, ester groups, carbonyl groups, ether groups, amino groups, imino groups, amide groups, cyano groups, diazo groups, nitro groups, and sulfone groups. and salts thereof, sulfonyl groups, sulfoxide groups, sulfide groups, thiol groups, phosphoric acid groups and salts thereof, phenyl groups, halogen atoms, double bonds, triple bonds, and other functional groups.

Examples of conjugated polyene compounds include isoprene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-t-butyl-1,3-butadiene, and 1,3-pentadiene. , 2,3-dimethyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 3,4-dimethyl-1,3-pentadiene, 3-ethyl-1,3-pentadiene, 2-methyl -1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene, 2,5-dimethyl-2,4-hexadiene , 1,3-octadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1-phenyl-1,3-butadiene, 1,4-diphenyl-1,3-butadiene, 1-methoxy-1,3 -Butadiene, 2-methoxy-1,3-butadiene, 1-ethoxy-1,3-butadiene, 2-ethoxy-1,3-butadiene, 2-nitro-1,3-butadiene, chloroprene, 1-chloro-1 , 3-butadiene, 1-bromo-1,3-butadiene, 2-bromo-1,3-butadiene, ocimene, phellandrene, myrcene, farnesene, sorbic acid, sorbic acid ester, sorbate, and other conjugated diene compounds;
Conjugated triene compounds such as 1,3,5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, cholecalciferol, fulvene, tropone;
Examples include conjugated polyene compounds such as cyclooctatetraene, 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid.

The molecular weight of the conjugated polyene compound is usually 1,000 or less, preferably 500 or less, and more preferably 300 or less. When the molecular weight of the conjugated polyene compound is 1,000 or less, the state of dispersion of the conjugated polyene compound in EVOH (A) is improved, and the appearance after melt molding is improved.

As the conjugated polyene compound, sorbic acid, sorbic acid ester, sorbate, myrcene, and mixtures of two or more of these are preferred, and sorbic acid, sorbate, and mixtures thereof are more preferred. Sorbic acid, sorbate salts, and mixtures thereof are highly effective in suppressing oxidative deterioration at high temperatures, and are also widely used industrially as food additives, so they are preferable from the viewpoint of hygiene and availability.

Compound (C) may be an unsaturated carboxylic acid or a salt thereof. Examples of such compounds include cinnamic acid, sorbic acid, and salts thereof. The number of carbon atoms in this unsaturated carboxylic acid is preferably 4 or more and 20 or less, more preferably 6 or more and 10 or less. Compound (C) may exist in the form of an anion.

In the resin composition of the present invention, the lower limit of the content (c) of the compound (C) relative to EVOH (A) is preferably 1 ppm, more preferably 5 ppm, even more preferably 10 ppm, and even more preferably 30 ppm. By setting the content (c) of the compound (C) to the above lower limit or more, the effect of containing the compound (C) can be particularly fully exhibited. On the other hand, the upper limit of this content (c) is preferably 1,000 ppm, more preferably 500 ppm, based on EVOH (A). When the content (c) of the compound (C) is below the above upper limit, the occurrence of lumps can be further reduced. The content of compound (C) in the entire resin composition of the present invention is also preferably within the above range. The above content (c) is the content (mass) of compound (C) per 1 g of EVOH (A), and the content (mass) of compound (C) with respect to the content (mass) of EVOH (A). ) is the ratio.

(Polyamide (D))
The resin composition of the present invention further contains polyamide (D) in order to improve the retort resistance and the like of the resin composition.

Polyamide (D) is a resin containing amide bonds. The polyamide (D) can be obtained, for example, by ring-opening polymerization of a lactam having three or more members, polycondensation of a polymerizable ω-amino acid, polycondensation of a dibasic acid and a diamine, and the like. Examples of the polyamide (D) include polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), polylauryllactam (nylon 12), polyethylenediamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide Mido (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactam/lauryllactam copolymer (nylon 6/12), caprolactam/ω-aminononanoic acid copolymer Coalescing (nylon 6/9), caprolactam/hexamethylene diammonium adipate copolymer (nylon 6/66), lauryl lactam/hexamethylene diammonium adipate copolymer (nylon 12/66), hexamethylene diammonium adipate/hexa Methylene diammonium sebacate copolymer (nylon 66/610), ethylene diammonium adipate/hexamethylene diammonium adipate copolymer (nylon 26/66), caprolactam/hexamethylene diammonium adipate/hexamethylene diammonium sebacate copolymer Polymers (nylon 6/66/610), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene terephthalamide (nylon 6T), hexamethylene isophthalamide/terephthalamide copolymer (nylon 6I/6T), etc. It will be done.

In addition, as diamines, aliphatic diamines with substituents such as 2,2,4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine; aromatic amines such as methylbenzylamine and metaxylylenediamine, etc. may be used, or they may be used to modify the polyamide. Furthermore, as dicarboxylic acids, aliphatic carboxylic acids with substituents such as 2,2,4-trimethyladipic acid and 2,4,4-trimethyladipic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; ; Aromatic dicarboxylic acids such as phthalic acid, xylylene dicarboxylic acid, alkyl-substituted terephthalic acid, alkyl-substituted isophthalic acid, naphthalene dicarboxylic acid, etc. may be used, and they may also be used to modify the polyamide. do not have.

Among these, polycapramide (nylon 6) is preferred. In addition, caprolactam/lauryllactam copolymer (nylon 6/12) is also preferred. In this case, the content ratio of 6 units and 12 units is not particularly limited, but the lower limit of the content of 12 units is preferably 5% by mass. On the other hand, the upper limit of the content of 12 units is preferably 60% by mass, more preferably 50% by mass.

The lower limit of the mass ratio (D/A) of polyamide (D) to EVOH (A) in the resin composition of the present invention is 5/95, preferably 8/92, and more preferably 13/87. Further, the upper limit of the mass ratio (D/A) is 40/60, preferably 35/65, more preferably 30/70, and even more preferably 25/75. By setting the mass ratio (D/A) to the above lower limit or more, the retort resistance of the resin composition can be improved, and after heat treatment with hot water or steam for a molded article formed from the resin composition. The occurrence of appearance defects is suppressed. Moreover, by making the mass ratio (D/A) below the above-mentioned upper limit, the characteristics such as gas barrier property and oil resistance that EVOH (A) originally has are particularly fully exhibited. Further, by setting the mass ratio (D/A) to be equal to or less than the above upper limit, generation of lumps during melt molding is suppressed.

The lower limit of the total content of EVOH (A) and polyamide (D) in the resin component of the resin composition of the present invention is preferably 80% by mass, more preferably 90% by mass, and even more preferably 95% by mass. Furthermore, the total content of EVOH (A) and polyamide (D) in the resin component of the resin composition is particularly preferably 100% by mass.

The lower limit of the content of polyamide (D) in the resin component of the resin composition of the present invention is preferably 4% by mass, more preferably 8% by mass, and even more preferably 12% by mass. On the other hand, the upper limit of the content of polyamide (D) is preferably 40% by mass, more preferably 35% by mass, even more preferably 30% by mass, and particularly preferably 25% by mass. By setting the content of polyamide (D) to the above lower limit or more, the retort resistance of the resin composition can be further improved. Moreover, by making the content of polyamide (D) below the above-mentioned upper limit, the content of EVOH (A) can be increased and gas barrier properties, oil resistance, etc. can be further improved. Further, by controlling the content of polyamide (D) to be below the above upper limit, the occurrence of lumps during melt molding is further suppressed.

(Metal atom (E))
The resin composition of the present invention further contains at least one metal atom (E) selected from the group consisting of magnesium, calcium, and zinc in order to improve long-run properties during melt molding and suppress generation of lumps. ing. Note that long-run property refers to the property that even when melt-molding is performed continuously over a long period of time, quality deterioration is difficult to occur and a good melt-molded product can be obtained.

The resin composition of the present invention contains 1 to 500 ppm of metal atoms (E) in terms of metal atoms based on EVOH (A), thereby suppressing the occurrence of lumps during melt molding and improving long-run properties. . The metal atom (E) is more preferably magnesium from the viewpoint of better long-run properties during melt molding.

The metal atom (E) may exist as a single metal atom or as a constituent atom in a compound, or may exist in the form of a free metal ion. The metal atom (E) is a salt of an organic acid such as aliphatic carboxylic acid, aromatic carboxylic acid, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, tricarboxylic acid, tetracarboxylic acid, hydroxycarboxylic acid, ketodicarboxylic acid, or amino acid; Salts of inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid, and phosphoric acid; may also be contained as hydroxides. Among these, it is preferably contained as a metal salt of aliphatic carboxylic acid or a hydroxide, and from the viewpoint of compatibility with EVOH (A) etc. It is more preferable that Examples of fatty acids include saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, and caproic acid; and unsaturated fatty acids such as acrylic acid and methacrylic acid. Among these, from the viewpoint of compatibility with EVOH (A) etc., salts and hydroxides of saturated fatty acids having 1 to 3 carbon atoms are preferred, and acetates and hydroxides are more preferred.

In the resin composition of the present invention, the metal atom (E) may form a salt with an organic acid or an inorganic acid as described above, or may form a salt as a counter cation of the alkoxide of EVOH (A). It's okay.

The lower limit of the content (e) of metal atoms (E) in EVOH (A) in the resin composition of the present invention is 1 ppm in terms of metal elements, preferably 20 ppm, and more preferably 30 ppm. When the content (e) of metal atoms (E) is 1 ppm or more, the occurrence of lumps during melt molding is sufficiently suppressed, and long run properties and stability of film thickness during film formation are excellent. On the other hand, the upper limit of the content (e) is 500 ppm, preferably 300 ppm, more preferably 150 ppm, and even more preferably 100 ppm. When the content (e) of metal atoms (E) is 500 ppm or less, the hue and film thickness stability during continuous film formation are excellent.

In the resin composition of the present invention, the metal atoms (E) are preferably uniformly dispersed throughout the resin composition. Further, the metal atoms (E) may be used alone or in combination of two or more.

(Other ingredients)
The resin composition of the present invention may contain resins other than EVOH (A) and polyamide (D), metal ions other than aluminum ions (B) and metal atoms (E), acids (compounds (Excluding those falling under (C)), boron compounds, plasticizers, fillers, antiblocking agents, lubricants, stabilizers, surfactants, colorants, ultraviolet absorbers, antistatic agents, desiccants, crosslinking agents, reinforcement It may also contain other components such as wood. Among them, from the viewpoint of thermal stability and adhesion with other resins, metal ions other than aluminum ions (B) and metal atoms (E), acids (excluding those falling under compounds (C)), and boron compounds. It is preferable to include one or more of the following.

Metal ions other than aluminum ions (B) and metal atoms (E) include alkali metal ions, since interlayer adhesion can be further improved when the resin composition of the present invention is used as a multilayer structure (laminate). preferable. These metal ions may be present in the form of salts.

When the resin composition of the present invention contains such metal ions, the content thereof is preferably 1 ppm or more, more preferably 5 ppm or more, even more preferably 10 ppm or more, even more preferably 20 ppm or more, and even more preferably 40 ppm or more. is particularly preferred. The content of metal ions other than aluminum ions (B) and metal atoms (E) is preferably 3,000 ppm or less, more preferably 1,000 ppm or less, even more preferably 500 ppm or less, and 300 ppm or less based on the resin composition. is particularly preferred. When the content of metal ions other than aluminum ions (B) and metal atoms (E) is within the above range, the multilayer structure can be recovered and recycled while maintaining good interlayer adhesion of the multilayer structure. Thermal stability tends to be better when exposed to heat.

As the acid (excluding those corresponding to compound (C)), carboxylic acid or phosphoric acid is preferable from the viewpoint of improving thermal stability during melt molding. Examples of carboxylic acids include formic acid, acetic acid, butyric acid, and lactic acid. As the carboxylic acid, a carboxylic acid having 4 or less carbon atoms or a saturated carboxylic acid is preferable, and acetic acid is more preferable. The acid may be present in salt or anionic form.

When the resin composition of the present invention contains a carboxylic acid, the content of the carboxylic acid is preferably 1 ppm or more, more preferably 10 ppm or more, and even more preferably 50 ppm or more. Further, the content of carboxylic acid is preferably 10,000 ppm or less, more preferably 1,000 ppm or less, and even more preferably 500 ppm or less. When the resin composition of the present invention contains phosphoric acid, the content of phosphoric acid is preferably 1 ppm or more, more preferably 10 ppm or more, and still more preferably 30 ppm or more in terms of phosphate radicals. Further, the content of the phosphoric acid compound is preferably 10,000 ppm or less, more preferably 1,000 ppm or less, and even more preferably 300 ppm or less. When the resin composition of the present invention contains carboxylic acid or phosphoric acid within the above range, it tends to have good thermal stability during melt molding.

Examples of boron compounds include boric acid, borate esters, borates, and boron hydride.

When the resin composition of the present invention contains a boron compound, the content of the boron compound is preferably 1 ppm or more, more preferably 10 ppm or more, based on the resin composition or EVOH (A). Moreover, the content of the boron compound is preferably 2,000 ppm or less, more preferably 1,000 ppm or less. When the resin composition of the present invention contains a boron compound within the above range, it tends to have good thermal stability during melt molding.

The method of incorporating each of these components into the resin composition of the present invention is not particularly limited, and can be carried out by conventionally known methods.

In the resin composition of the present invention, EVOH (A), aluminum ion (B), compound (C), polyamide (D), metal ion other than aluminum ion (B) and metal atom (E), acid (compound (C) The upper limit of the content of components other than boron compounds (excluding those applicable to Sometimes it's desirable.

(melt flow rate)
The lower limit of the melt flow rate of the resin composition of the present invention at a temperature of 210° C. and a load of 2,160 g is preferably 1.0 g/10 minutes, more preferably 2.0 g/10 minutes. On the other hand, the upper limit of this melt flow rate is preferably 30 g/10 minutes, more preferably 20 g/10 minutes, and even more preferably 10 g/10 minutes. When the melt flow rate of the resin composition of the present invention is within the above range, melt moldability, processability, etc. will be good.

(Method for manufacturing resin composition)
The method for producing the resin composition of the present invention includes producing a resin composition containing EVOH (A) and aluminum ions (B), and then combining this resin composition with polyamide (D) and metal atoms (E). Examples include a method of mixing, a method of mixing EVOH (A), aluminum ions (B), polyamide (D), and metal atoms (E) all at once.

As a method for producing a resin composition containing EVOH (A) and aluminum ions (B), for example, 1) a porous precipitate of EVOH (A) with a water content of 20 to 80% by mass is mixed with an aluminum salt, etc. 2) A method in which EVOH (A) is brought into contact with an aqueous dispersion to contain an aluminum salt, etc., and then dried; 2) A homogeneous solution (water/alcohol solution, etc.) of EVOH (A) is made to contain an aluminum salt, etc. 3) a method of dry blending EVOH (A) and aluminum salt etc. all at once; 4) A method of dry blending EVOH (A) and aluminum salt etc. all at once and then melt-kneading them with an extruder etc., 5) A method of obtaining an ethylene-vinyl ester copolymer during the production of EVOH (A) , aluminum salt, etc. can be mentioned. In order to obtain the effects of the present invention more markedly, methods 1), 2) and 5) are preferred because they provide excellent dispersibility of aluminum ions (B).

In the methods 1) and 2) above, after the aluminum salt etc. are added, and in the method 5), after the ethylene-vinyl ester copolymer is obtained, the saponification step and the washing step are performed. , usually followed by drying. As such a drying method, various drying methods can be adopted. For example, a substantially pellet-like resin composition is subjected to fluidized drying while being stirred and dispersed mechanically or with hot air, and a substantially pellet-like resin composition is subjected to dynamic actions such as stirring and dispersion. One example is drying that is performed without being applied. Examples of the dryer for fluidized drying include a cylindrical and groove type stirring dryer, a cylindrical tube dryer, a rotary dryer, a fluidized bed dryer, a vibrating fluidized bed dryer, a conical rotary dryer, and the like. As a dryer for performing stationary drying, a batch type box type dryer is used as a material stationary type, and a band dryer, tunnel dryer, vertical type dryer, etc. are listed as a material transfer type. Fluidized drying and stationary drying may be performed in combination.

Air or an inert gas (nitrogen gas, helium gas, argon gas, etc.) is used as the heating gas used during the drying process. ) is preferable in terms of suppressing thermal deterioration. The time for the drying treatment depends on the water content of the resin composition and the amount of treatment, but is usually preferably about 15 minutes to 72 hours from the viewpoint of productivity and prevention of thermal deterioration of EVOH (A).

Further, as the method 4) above, there is, for example, a method of melt-kneading using a single-screw or twin-screw extruder. The melt-kneading temperature is usually 150 to 300°C, preferably 170 to 250°C.

The resin composition containing EVOH (A) and aluminum ions (B), polyamide (D) and metal atoms (E) can be mixed by a known method such as melt kneading. The metal atom (E) is usually mixed as a compound containing the metal atom (E). At this time, other components may be added and melt-kneaded. As a method of mixing EVOH (A), aluminum ions (B), polyamide (D) and metal atoms (E) all at once, in the method 3), 4) or 5) of producing the above mixture, aluminum salt In addition, a method of dry blending or adding polyamide (E) and a compound containing a metal atom (E) can be mentioned. At this time, other components may be dry blended or added in the same manner.

The resin composition of the present invention can be processed into any form such as pellets or powder and used as a molding material, and is usually in a dry state. The upper limit of the water content relative to the total solid content of the resin composition of the present invention may be preferably 1% by mass, and more preferably 0.1% by mass or 0.01% by mass. When the resin composition of the present invention is in a dry state, it can exhibit good melt moldability and the like.

<Molded object>
The resin composition of the present invention can be molded into molded objects such as films, sheets, tubes, bags, containers, etc. by melt molding or the like. That is, the molded article of the present invention is a molded article molded from the resin composition of the present invention. The molded article of the present invention may be formed only from the resin composition of the present invention, or may have portions formed from other materials. For example, a multilayer structure (laminate) described below is also one form of a molded product.

The molded product of the present invention suppresses the occurrence of lumps during melt molding, has sufficient heat and light resistance, and is difficult to turn into microplastic after disposal, and has sufficient characteristics as described above compared to products using the same EVOH. has been improved. In addition, the molded article has less appearance defects after heat treatment with hot water or steam such as retort treatment. Therefore, the resin composition of the present invention is particularly useful as a melt molding material.

Examples of methods for melt molding the resin composition of the present invention include extrusion molding, cast molding, inflation extrusion molding, blow molding, melt spinning, injection molding, and injection blow molding. The melt molding temperature varies depending on the melting point of EVOH (A), etc., but is preferably about 150 to 270°C. These molded bodies can also be crushed and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets, etc.

<Multilayer structure (laminate)>
The above-mentioned molded product may be a molded product with a single layer structure consisting only of a layer formed from the resin composition (hereinafter also referred to as "barrier layer"), but a layer made of the resin composition (barrier layer) may be used. It may be a multilayer structure including. The lower limit of the number of layers in the multilayer structure is, for example, two, may be three, or may be four. The upper limit of this number of layers is, for example, 1,000, which may be 100, or may be 20. The multilayer structure preferably includes a barrier layer and another layer, particularly a thermoplastic resin layer, laminated on at least one surface of the barrier layer. Since the multilayer structure includes a barrier layer and a thermoplastic resin layer, it has excellent appearance, retort resistance, and processing characteristics. In addition, the multilayer structure suppresses the occurrence of lumps during molding, has sufficient heat and light resistance, and is difficult to turn into microplastics after disposal, and has all of the above characteristics sufficiently compared to those using the same EVOH. has been improved. In addition, the multilayer structure has less appearance defects after heat treatment with hot water or steam such as retort treatment.

Examples of the multilayer structure include multilayer sheets, multilayer pipes, multilayer fibers, and the like. As the other layer constituting the multilayer structure, a thermoplastic resin layer formed of, for example, a thermoplastic resin is preferable. The multilayer structure includes a barrier layer and a thermoplastic resin layer, and thus has excellent appearance and heat stretchability.

Examples of the thermoplastic resin include:
high density, medium density or low density polyethylene;
Polyethylene copolymerized with vinyl acetate, acrylic ester, or α-olefins such as butene and hexene;
Ionomer;
polypropylene homopolymer;
Polypropylene copolymerized with α-olefins such as ethylene, butene, and hexene;
Polyolefins such as modified polypropylene blended with rubber polymers;
Resins obtained by adding or grafting maleic anhydride to these resins;
Examples include polyester.

Further examples of the thermoplastic resin include polyamide, polystyrene, polyvinyl chloride, acrylic resin, polyurethane, polycarbonate, polyvinyl acetate, and the like.

Among these, polyethylene, polypropylene, polyamide and polyester are preferred as the thermoplastic resin. As specific resin materials for forming the thermoplastic resin layer, unstretched polypropylene film and nylon 6 film are preferred.

The layer structure of the multilayer structure is not particularly limited, but from the viewpoint of moldability and cost, thermoplastic resin layer/barrier layer/thermoplastic resin layer, barrier layer/adhesive resin layer/thermoplastic layer, etc. Representative examples include resin layer, thermoplastic resin layer/adhesive resin layer/barrier layer/adhesive resin layer/thermoplastic resin layer. Among these layer structures, preferred are thermoplastic resin layer/barrier layer/thermoplastic resin layer and thermoplastic resin layer/adhesive resin layer/barrier layer/adhesive resin layer/thermoplastic resin layer. When providing thermoplastic resin layers on both outer layers of the barrier layer, the thermoplastic resin layers on both outer layers may be made of different resins or may be made of the same resin.

Methods for producing the multilayer structure are not particularly limited, but include, for example, extrusion lamination, dry lamination, extrusion blow molding, coextrusion lamination, coextrusion, coextrusion pipe molding, Examples include a coextrusion blow molding method, a co-injection molding method, and a solution coating method.

Among these methods, coextrusion lamination and coextrusion molding are preferred as methods for manufacturing the multilayer sheet, and coextrusion molding is more preferred. By laminating the barrier layer and the thermoplastic resin layer by the above method, they can be easily and reliably manufactured, and as a result, high appearance, retort resistance, and processing characteristics can be effectively achieved. .

Examples of the method for forming a molded article using the multilayer sheet include a heat stretch molding method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a blow molding method, and the like. These moldings are usually performed at a temperature range below the melting point of EVOH. Among these, the hot stretch molding method and the vacuum pressure molding method are preferred. The heating stretch molding method is a method in which a multilayer sheet is heated, stretched in one direction or in multiple directions, and then molded. The vacuum-pressure forming method is a method in which a multilayer sheet is heated and formed using a combination of vacuum and air pressure. As the above-mentioned molded article, a packaging material formed by forming the above-mentioned multilayer sheet by a hot stretch molding method can be easily and reliably produced, and has an excellent appearance and suppresses stretching unevenness. can. Further, a container formed by molding the above-mentioned multilayer sheet by vacuum-pressure forming can be easily and reliably manufactured, and can have excellent appearance and retort resistance. Moreover, these packaging materials and containers are suitable for boil sterilization and retort sterilization.

In the above hot stretch molding method, it is preferable that the extruded multilayer sheet is rapidly cooled immediately after extrusion to make it substantially as amorphous as possible. Next, this multilayer sheet is reheated to a temperature below the melting point of EVOH (A), and uniaxially or biaxially stretched by a roll stretching method, a pantograph stretching method, an inflation stretching method, or the like. The lower limit of the stretching ratio is usually 1.3 times, preferably 1.5 times, in each of the vertical and/or horizontal directions. The upper limit of the stretching ratio is usually 9 times, preferably 4 times, in each of the longitudinal and/or transverse directions. The lower limit of the heating temperature is usually 50°C, preferably 60°C. The upper limit of the heating temperature is usually 140°C, preferably 100°C. If the heating temperature is less than 50°C, the stretchability will be poor and the dimensional change will be large.

When the above-mentioned packaging material is manufactured from a multilayer sheet using a hot stretch molding method, by using the above-mentioned resin as a thermoplastic resin, the appearance can be made more excellent, and defects such as cracks can be further suppressed. can do.

Moreover, the said molded object can also be shape|molded by the co-injection stretch blow molding method using the said resin composition mentioned above and other resin compositions. The co-injection stretch blow molding method is a method in which a preform having a multilayer structure is obtained by co-injection molding using, for example, two or more resin compositions, and then this preform is heated and stretch blow molded. By molding a resin composition having the above-mentioned characteristics using a co-injection stretch blow molding method, the molded article can be easily and reliably produced and has an excellent appearance. Examples of the other resin compositions include the above-mentioned thermoplastic resins.

Note that scraps generated during thermoforming such as extrusion molding and blow molding may be blended into the thermoplastic resin layer and reused, or may be used as a separate recovery layer.

In the above-mentioned vacuum-pressure forming method, for example, a multilayer sheet is heated to soften it and then formed into a mold shape. The molding method uses vacuum or compressed air (compressed air), and if necessary, a plug is also used to mold into a mold shape (straight method, drape method, air slip method, snapback method, plug assist method, etc.) , a method of press molding, etc. Various molding conditions such as molding temperature, degree of vacuum, compressed air pressure, molding speed, etc. are appropriately set depending on the shape of the plug, the shape of the mold, the properties of the raw material film or sheet, etc.

The molding temperature is not particularly limited, and may be any temperature at which the resin is sufficiently softened for molding. For example, when thermoforming a multilayer sheet, the temperature should not be so high that the multilayer sheet would melt due to heating or the unevenness of the metal surface of the heater plate would be transferred to the multilayer sheet, and the shaping should be sufficient. It is desirable not to set the temperature to such a low temperature that the Specifically, the lower limit of the temperature of the multilayer sheet is usually 50°C, preferably 60°C. The upper limit of the above temperature is usually 180°C, preferably 160°C.

<Container>
The container of the present invention is a container made of the multilayer structure described above. The container suppresses the occurrence of lumps during molding, has sufficient heat and light resistance, and is difficult to turn into microplastics after disposal, and each of the above characteristics is sufficiently improved compared to a container using the same EVOH. There is. In addition, the container is also prevented from developing poor appearance after heat treatment with hot water or steam such as retort treatment. Therefore, the container can be particularly suitably used as a container for boil sterilization or retort sterilization.

The container is manufactured, for example, by thermoforming the multilayer structure (multilayer sheet) into a three-dimensional shape in which a recess is formed in the plane. The container is suitably formed by the vacuum-pressure forming method described above. The shape of the recess is determined depending on the shape of the contents, but the deeper the recess or the less smooth the shape of the recess, the more likely it is that uneven thickness will occur in a normal EVOH laminate. Since the film becomes extremely thin, the improvement effect of the present invention is large. When the container is formed from a multilayer film having a total thickness of less than about 300 μm, the drawing ratio (S) is preferably 0.2 or more, more preferably 0.3 or more, and still more preferably The effects of the present invention are more effectively exhibited when the ratio is 0.4 or more. Further, when the container is formed by molding a multilayer sheet having a total thickness of about 300 μm or more, the drawing ratio (S) is preferably 0.3 or more, more preferably 0.5 or more, and The effects of the present invention are preferably exhibited more effectively when the ratio is 0.8 or more.

Here, the aperture ratio (S) refers to a value calculated by the following formula (1).

S = (depth of the container) / (diameter of the circle with the largest diameter inscribed in the opening of the container)
... (1)

In other words, the drawing ratio (S) is the value of the depth of the deepest part of the container divided by the value of the diameter of the largest inscribed circle that is in contact with the shape of the recess (opening) formed in the plane of the multilayer sheet. It is a value. The diameter of this circle is, for example, the diameter of the recess if it is a circle, its short axis if it is an ellipse, and the length of its short side if it is a rectangle. is the value of the diameter of

EXAMPLES Hereinafter, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples. The methods of measurement, calculation, and evaluation were as follows.

<Measurement conditions for quantitative determination of the primary structure of EVOH (NMR method)>
Device name: JEOL superconducting nuclear magnetic resonance device ECZ-600
Observation frequency: 600MHz (1H)
(1) Solvent: heavy dimethyl sulfoxide (DMSO-d ₆ ) Polymer concentration: 5% by mass Measurement temperature: 25°C, 80°C
Flip angle: 30° Accumulation count: 256s
Internal standard substance: Tetramethylsilane (TMS)
(2) Solvent: heavy water (D ₂ O) + heavy methanol (MeOD) (mass ratio 4/6) Polymer concentration: 5% by mass Measurement temperature: 80°C
Flip angle: 30° Accumulation count: 1024s
Internal standard substance: Tetramethylsilane (TMS)

<Determination of ethylene unit content, saponification degree, terminal carboxylic acid unit content, and terminal lactone ring unit content>
The ethylene unit content (Et Cont.), saponification degree (SP), terminal carboxylic acid unit content (α), and terminal lactone ring unit content (β) of EVOH were determined by ¹ H-NMR measurement (DMSO-d ₆ solvent). : measurement results at 25°C and 80°C, measurement results with D ₂ O + MeOD solvent). Note that the chemical shift value was based on the TMS peak of 0 ppm. Moreover, in the formula, VAc, VAl and Et represent a vinyl acetate unit, a vinyl alcohol unit and an ethylene unit, respectively.
I1, I3: 0.4 to 2.35 ppm methylene hydrogen integral value (I1: DMSO-d ₆ measured value at 25°C, I3: DMSO-d ₆ measured value at 80°C)
I9:: Integral value of methylene hydrogen from 0.4 to 2.8 ppm (measured value in D ₂ O + MeOD solvent)
I2: Integral value of methine hydrogen in vinyl alcohol unit (methine hydrogen on both sides of the same unit is vinyl alcohol) of 3.4 to 4.0 ppm (DMSO-d ₆ measured value at 25°C)
I4: 3.15 to 3.45 ppm integral value of methine hydrogen in vinyl alcohol unit (methine hydrogen on both sides of the same unit is vinyl alcohol) (DMSO-d ₆ measured value at 80°C)
I5: Integral value derived from hydrogen of terminal methyl group in vinyl acetate unit (DMSO-d ₆ measured value at 80°C)
I6: Integral value around 1.8 to 1.85 (DMSO-d ₆ measured value at 80°C)
I7: Integral value derived from the hydrogen of the methyl group in the -CH(OH)CH ₃ group present at the polymer terminal of EVOH (DMSO-d ₆ measured value at 80°C)
I8: Integral value derived from the hydrogen of the methyl group in the -CH ₂ CH ₃ group present at the polymer end of EVOH (DMSO-d ₆ measured value at 80°C)
I10: Integral value around 0.8 to 0.95 (measured value with D ₂ O + MeOD solvent)
I11: Integral value derived from the hydrogen of the CH ₂ unit adjacent to the carbonyl group of the terminal lactone ring unit (measured value in D ₂ O + MeOD solvent)
I12: Integral value derived from the linear COOH group of the terminal carboxylic acid unit (measured value in D ₂ O + MeOD solvent)
I13, I14: Integral value derived from carboxylate of terminal carboxylic acid unit (measured value in D ₂ O + MeOD solvent)
Note that the determined ethylene unit content (Et Cont.), terminal carboxylic acid unit content (α), and terminal lactone ring unit content (β) are the total amount of ethylene units, vinyl ester units, and vinyl alcohol units. It is the percentage (mol%) of the amount (mol) of each unit relative to (mol). However, the content of units other than ethylene units, vinyl ester units, and vinyl alcohol units is extremely small compared to these units. Therefore, the determined ethylene unit content (Et Cont.), terminal carboxylic acid unit content (α), and terminal lactone ring unit content (β) are all based on the amount of each unit relative to the total amount (mol) of all structural units. It is substantially equal to the percentage (mol%) of the amount (mol).

<Measurement of melt flow rate (MFR)>
The dried resin composition pellets obtained in each reference example and reference comparative example were filled into a cylinder with an inner diameter of 9.55 mm and a length of 162 mm of Melt Indexer L244 (manufactured by Takara Kogyo Co., Ltd.), and after melting at 210 ° C. A load was evenly applied to the molten resin composition using a plunger having a mass of 2,160 g and a diameter of 9.48 mm. The amount of resin composition extruded per unit time (g/10 minutes) from an orifice with a diameter of 2.1 mm provided at the center of the cylinder was measured, and this was defined as MFR.

<Sodium ion content, phosphoric acid content and boric acid content>
0.5 g of the dried resin composition pellets obtained in each reference example and reference comparative example were placed in a Teflon (registered trademark) pressure vessel, and 5 mL of concentrated nitric acid was added thereto to decompose at room temperature for 30 minutes. After 30 minutes, the lid was closed, and the mixture was decomposed by heating at 150° C. for 10 minutes, then at 180° C. for 5 minutes using a wet decomposition device (“MWS-2” manufactured by Actac Co., Ltd.), and then cooled to room temperature. This treated solution was transferred to a 50 mL volumetric flask (manufactured by TPX (registered trademark)) and diluted with pure water. This solution was analyzed for metal content using an ICP emission spectrometer (PerkinElmer's "OPTIMA4300DV"), and the content of sodium ions (sodium element) and phosphoric acid was determined as a phosphate radical equivalent value, and the content of boric acid was The amount was calculated as a boron element equivalent value. For quantitative determination, calibration curves prepared using commercially available standard solutions were used.

<Acetic acid content>
20 g of the dried resin composition pellets obtained in each reference example and reference comparative example were poured into 100 ml of ion-exchanged water, and extracted by heating at 95° C. for 6 hours. Using phenolphthalein as an indicator, the extract was neutralized and titrated with 1/50 normal NaOH to quantify the acetic acid content.

<Sorbic acid content>
The dry resin composition pellets obtained in each Reference Example and Reference Comparative Example were freeze-pulverized, and coarse particles were removed using a sieve with a nominal size of 0.150 mm (100 mesh) (compliant with JIS standard Z8801-1 to 3). 22 g of the pulverized material was filled into a Soxhlet extractor, and extracted with 100 mL of chloroform for 16 hours. The amount of sorbic acid in the obtained chloroform extract was quantitatively analyzed by high performance liquid chromatography to determine the content of sorbic acid in the resin composition. In addition, for the quantitative determination, a calibration curve prepared using a standard sample of sorbic acid was used.

<Cinnamic acids content>
The dry resin composition pellets obtained in each Reference Example and Reference Comparative Example were freeze-pulverized, and coarse particles were removed using a sieve with a nominal size of 0.150 mm (100 mesh) (compliant with JIS standard Z8801-1 to 3). 22 g of the pulverized material was filled into a Soxhlet extractor, and extracted with 100 mL of acetone for 16 hours. The amount of cinnamic acid in the obtained acetone extract was quantitatively analyzed by high performance liquid chromatography to determine the content of cinnamic acid in the resin composition. In addition, for quantitative determination, a calibration curve prepared using a standard sample of cinnamic acid was used.

<Aluminum ion content>
15 g of the dry resin composition pellets obtained in each reference example and reference comparative example were weighed into a platinum crucible, and dry decomposition was performed using nitric acid and sulfuric acid. 2 mL of hydrochloric acid was added to the incinerated sample, the volume was fixed in a 50 mL volumetric flask made of polytetrafluoroethylene (PTFE), and the mixture was filtered through a PTFE filter with a pore size of 0.45 μm to prepare a sample solution. Using the solution, the aluminum ion content in the resin composition was measured by high frequency plasma emission spectrometry (ICP emission spectrometer "IRIS AP" manufactured by Jarrell Ash).

<Synthesis Example 1> Synthesis of EVOH-A Vinyl acetate (hereinafter sometimes referred to as VAc) was placed in a 200 L pressurized reaction tank equipped with a jacket, a stirrer, a nitrogen inlet, an ethylene inlet, and an initiator addition port. 75.0 kg and 7.2 kg of methanol (hereinafter sometimes referred to as MeOH) were charged, and the inside of the reaction tank was purged with nitrogen by bubbling nitrogen for 30 minutes. Next, after adjusting the temperature in the reaction tank to 65°C, ethylene was introduced so that the pressure in the reaction tank (ethylene pressure) was 4.13 MPa, and 9.4 g of 2,2'-azobis(2 ,4-dimethylvaleronitrile) (“V-65” manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added to initiate polymerization. During the polymerization, the ethylene pressure was maintained at 4.13 MPa and the polymerization temperature was maintained at 65°C. After 4 hours, when the conversion rate of VAc (polymerization rate based on VAc) reached 49.7%, it was cooled and a solution of 0.2 g of copper acetate dissolved in 20 kg of methanol was put into the container to start polymerization. It stopped. After the reaction tank was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. The polymerization solution was then withdrawn from the vessel and diluted with 20 L of MeOH. This liquid is fed from the top of the tower-shaped container, and MeOH vapor is fed from the bottom of the tower to remove unreacted monomers remaining in the polymerization liquid together with the MeOH vapor, resulting in ethylene-vinyl acetate copolymer (hereinafter referred to as A MeOH solution of (sometimes referred to as EVAc) was obtained.
Next, 150 kg of a 20% by mass MeOH solution of EVAc was charged into a 300 L reaction tank equipped with a jacket, a stirrer, a nitrogen inlet, a reflux condenser, and a solution addition port. This solution was heated to 60° C. while blowing nitrogen gas, and a MeOH solution having a sodium hydroxide concentration of 2N was added at a rate of 450 mL/min for 2 hours. After completing the addition of the sodium hydroxide MeOH solution, the temperature inside the system was kept at 60°C and the saponification reaction was carried out by stirring for 2 hours while flowing MeOH and methyl acetate produced in the saponification reaction out of the reaction tank. I let it progress. Thereafter, 8.7 kg of acetic acid was added to stop the saponification reaction.
Thereafter, 120 L of ion-exchanged water was added while heating and stirring at 80° C., MeOH was flowed out of the reaction tank, and EVOH was precipitated. The precipitated EVOH was collected by decantation and pulverized using a pulverizer. The obtained EVOH powder was poured into a 1 g/L acetic acid aqueous solution (bath ratio 20: ratio of 20 L of aqueous solution to 1 kg of powder) and washed with stirring for 2 hours. This was deliquified and further poured into a 1 g/L aqueous acetic acid solution (bath ratio 20) and washed with stirring for 2 hours. The deliquified product was poured into ion-exchanged water (bath ratio 20), stirred and washed for 2 hours, and deliquified three times for purification. The electrical conductivity of the cleaning solution was 3 μS/cm (measured with “CM-30ET” manufactured by Toa Denpa Kogyo Co., Ltd.). Next, it was immersed in 250 L of an aqueous solution containing 0.5 g/L of acetic acid and 0.1 g/L of sodium acetate with stirring for 4 hours, and then the liquid was removed, and this was dried at 60°C for 16 hours to obtain a crude dried product of EVOH. I gained 16.1 kg. The above operation was performed again to obtain 15.9 kg of a crude dried EVOH, thereby obtaining a total of 32.0 kg of a crude dried EVOH (EVOH-A).

<Preparation of resin composition>
[Reference Examples 1 to 6 and Reference Comparative Examples 1 to 3]
A 60 L stirring tank equipped with a jacket, a stirrer, and a reflux condenser was charged with 2 kg of the crude dried EVOH (EVOH-A) obtained in Synthesis Example 1, 0.8 kg of water, and 2.2 kg of MeOH, and the mixture was heated at 60°C for 5 hours. Stir to completely dissolve. Aluminum acetate was added to the obtained solution, and the mixture was further stirred for 1 hour to completely dissolve the aluminum acetate, thereby obtaining a resin composition solution. In addition, in Reference Comparative Example 3, a resin composition solution was obtained without adding aluminum acetate. This solution is extruded through a metal plate with a diameter of 4 mm into a mixed solution of water/MeOH = 90/10 cooled to -5°C to precipitate it in the form of a strand, and the strand is cut into pellets with a strand cutter. A hydrous pellet was obtained. The water content of the obtained EVOH water-containing pellets was measured with a halogen moisture meter "HR73" manufactured by Mettler, and was found to be 52% by mass. The obtained EVOH water-containing pellets were poured into a 1 g/L acetic acid aqueous solution (bath ratio 20) and washed with stirring for 2 hours. This was deliquified and further poured into a 1 g/L aqueous acetic acid solution (bath ratio 20) and washed with stirring for 2 hours. After removing the liquid, the acetic acid aqueous solution was renewed and the same operation was performed. After washing with an acetic acid aqueous solution and deliquifying it, we poured it into ion-exchanged water (bath ratio 20), washed it with stirring for 2 hours, and deliquified it three times, until the electrical conductivity of the washing liquid was 3 μS/ cm (measured with "CM-30ET" manufactured by Toa Denpa Kogyo Co., Ltd.) and purified to obtain water-containing EVOH pellets from which the catalyst residue from the saponification reaction was removed.
The water-containing pellets were placed in an aqueous solution (bath ratio 20) with a sodium acetate concentration of 0.510 g/L, an acetic acid concentration of 0.8 g/L, and a phosphoric acid concentration of 0.04 g/L, and stirred regularly for 4 hours. It was immersed and chemically treated. The pellets were deliquified and dried at 80°C for 3 hours and at 105°C for 16 hours under a nitrogen stream with an oxygen concentration of 1% by volume or less to remove EVOH-A, acetic acid, sodium ions (sodium salts), phosphoric acid, and Dry cylindrical resin composition pellets containing aluminum ions (aluminum salt) and having an average diameter of 2.8 mm and an average length of 3.2 mm were obtained. In each reference example and reference comparative example, the aluminum ion content was adjusted as shown in Table 3 by adjusting the amount of aluminum acetate added. Ethylene content, saponification degree, terminal lactone ring unit content, terminal carboxylic acid unit content, total content of terminal carboxylic acid units and terminal lactone ring units of EVOH-A in the obtained dry resin composition pellets, The lactone ring unit ratio, MFR, and boric acid content were determined using the above quantitative method using a dry resin composition pellet having an aluminum ion content of 0.3 ppm as a sample (the same applies hereinafter). Table 2 shows the ethylene content, degree of saponification, content of terminal lactone ring units, content of terminal carboxylic acid units, total content of terminal carboxylic acid units and terminal lactone ring units, lactone ring unit ratio, MFR and boric acid content. Shown below. In addition, in all dried resin composition pellets, the sodium ion content was 90 to 110 ppm, the phosphoric acid content was 35 to 45 ppm in terms of phosphate radical, and the acetic acid content was 190 to 210 ppm. Further, FIG. 1 shows the ¹ H-NMR spectrum of EVOH-A measured under the conditions of a solvent DMSO-d ₆ and a measurement temperature of 25°C. FIG. 2 shows the ¹ H-NMR spectrum of EVOH-A measured under the conditions of a solvent DMSO-d ₆ and a measurement temperature of 80°C. FIG. 3 shows the ¹ H-NMR spectrum of EVOH-A measured under the conditions of solvent D ₂ O+MeOD and measurement temperature: 80°C.

<Synthesis Examples 2 to 11>
The amounts of raw materials used for polymerization of EVOH, the polymerization conditions, the amount charged in saponification treatment, and the addition rate of 2N sodium hydroxide MeOH solution were as shown in Table 1, and the synthesis was performed only once. In the same manner as in Example 1, 10.1 to 11.5 kg of crude dry matter of each EVOH (EVOH-B to EVOH-K) was obtained.

<Preparation of resin composition>
[Reference Examples 7 to 27, 34 and Reference Comparative Examples 4 to 23]
Reference Example except that the crude dried products of each EVOH (EVOH-B to EVOH-K) obtained in Synthesis Examples 2 to 11 above were used, and each component contained in the aqueous solution in the chemical treatment was as shown in Table 1. Each dried resin composition pellet was obtained in the same manner as in Example 1. Further, as in Reference Example 1, the aluminum ion content was adjusted as shown in Tables 3 to 12 and 14 by adjusting the amount of aluminum acetate added. Various measurements were also carried out in the same manner as in Reference Example 1 using the above quantitative method. Table 2 shows the ethylene content, degree of saponification, content of terminal lactone ring units, content of terminal carboxylic acid units, total content of terminal carboxylic acid units and terminal lactone ring units, lactone ring unit ratio, MFR and boric acid content. Shown below. In addition, the sodium ion content of all dried resin composition pellets was 90 to 110 ppm, the phosphoric acid content was 35 to 45 ppm in terms of phosphate radical, and the acetic acid content was 190 to 210 ppm.

<Preparation of resin composition>
[Reference Examples 28 to 33 and Reference Comparative Example 24]
2 kg of crudely dried EVOH (EVOH-A) obtained in Synthesis Example 1 above, 0.8 kg of water, and 2.2 kg of MeOH were charged and stirred at 60° C. for 5 hours to completely dissolve. Aluminum acetate, sorbic acid, or cinnamic acid was added to the resulting solution, and the mixture was further stirred for 1 hour to completely dissolve aluminum acetate and sorbic acid or cinnamic acid, thereby obtaining a resin composition solution. In addition, in Reference Comparative Example 24, a resin composition solution was obtained by adding only sorbic acid without adding aluminum acetate. The subsequent treatments were carried out in the same manner as in Reference Example 1 to obtain each dried resin composition pellet. The aluminum ion content was adjusted by adjusting the amount of aluminum acetate added, and the content of sorbic acid or cinnamic acid was adjusted by adjusting the amount of these additions to obtain dry resin composition pellets as shown in Table 13. Ta. Various measurements were also carried out in the same manner as in Reference Example 1 using the above quantitative method. In all dried resin composition pellets, the sodium ion content was 90 to 110 ppm, the phosphoric acid content was 35 to 45 ppm in terms of phosphate radical, and the acetic acid content was 190 to 210 ppm.

In addition, in Tables 3 to 14, the total content (mol%) of terminal carboxylic acid units and lactone ring units with respect to the total amount of ethylene units, vinyl alcohol units, and vinyl acetate units in EVOH is shown, as well as the total content (mol%) of EVOH per gram of EVOH. The total content (μmol/g) of terminal carboxylic acid units and terminal lactone ring units per unit is also shown. In addition to the aluminum ion content (ppm) in the resin composition, the aluminum ion content (μmol/g) per 1 g of EVOH is also shown. Furthermore, the ratio ((i+ii)/b ) are also shown.

<Preparation of polyamide (D) blend resin composition>
[Examples 1 to 7, Comparative Examples 3 to 5]
A resin composition containing EVOH-A and EVOH-D obtained in Reference Examples 2 and 14, respectively, a polyamide resin (“Ny1018A” (nylon 6) manufactured by Ube Industries, Ltd.), and a compound containing a metal atom (E), After dry blending at the blending ratio shown in Table 15 (the content of metal atoms (E) is converted into metal atoms), a twin-screw extruder ("2D25W" manufactured by Toyo Seiki Seisakusho Co., Ltd., 25 mmφ) was used to dry the mixture at a die temperature of 250. Resin composition pellets were obtained by extrusion under nitrogen atmosphere under extrusion conditions of 100 rpm and 100 rpm.

[Comparative example 1]
The resin composition containing EVOH-A obtained in Reference Comparative Example 1, the polyamide resin (“Ny1018A” (nylon 6) manufactured by Ube Industries, Ltd.), and the compound containing the metal atom (E) were mixed at the blending ratio shown in Table 15. After dry blending, the resin composition is obtained by extruding it under nitrogen atmosphere using a twin screw extruder (2D25W manufactured by Toyo Seiki Seisakusho Co., Ltd., 25 mmφ) under extrusion conditions of die temperature 250°C and screw rotation speed 100 rpm. Obtained pellets.

[Comparative example 2]
The resin composition containing EVOH-A obtained in Reference Comparative Example 2, the polyamide resin (“Ny1018A” (nylon 6) manufactured by Ube Industries, Ltd.), and the compound containing the metal atom (E) were mixed at the blending ratio shown in Table 15. After dry blending, the resin composition is obtained by extruding it under nitrogen atmosphere using a twin screw extruder (2D25W manufactured by Toyo Seiki Seisakusho Co., Ltd., 25 mmφ) under extrusion conditions of die temperature 250°C and screw rotation speed 100 rpm. Obtained pellets.

<Evaluation>
<Single layer film production conditions>
Each resin composition pellet obtained in Reference Examples 1 to 34, Reference Comparative Examples 1 to 24, Examples 1 to 7, and Comparative Examples 1 to 5 was formed into a film under the following conditions to obtain a single layer film with a thickness of 20 μm. Ta.
・Equipment: 20mmφ single screw extruder (D2020, manufactured by Toyo Seiki Seisakusho Co., Ltd.)
・L/D: 20
・Screw: Full flight ・Dice width: 30cm
・Take-up roll temperature: 80℃
・Screw rotation speed: 40 rpm
・Take-up roll speed: 3.0 to 3.5 m/min Reference Examples 1 to 34 and Reference Comparative Examples 1 to 24
・Set temperature: C1/C2/C3/D=180℃/210℃/210℃/210℃
Examples 1 to 7 and Comparative Examples 1 to 5
・Set temperature: C1/C2/C3/D=200℃/230℃/230℃/230℃

<Suppression of the occurrence of bumps (spots)>
Fifty hours after the start of operation, the number of gel-like lumps (visible to the naked eye of 150 μm or more) in the single-layer film produced was counted and calculated per 1.0 m ² . Judgment was made as follows based on the number of particles per 1.0 ^m2 . The evaluation results are shown in Tables 3 to 14 and 16.
A: Less than 20 pieces B: 20 pieces or more and less than 40 pieces C: 40 pieces or more and less than 100 pieces D: 100 pieces or more If the evaluation result is between A and B, the occurrence of bumps has been sufficiently suppressed and no problem will occur. level. Even when the evaluation result is C, the occurrence of spots is suppressed, and although spots may become a problem depending on the application, it is at a usable level. If the evaluation result is D, there are a large number of particles and it is at an unusable level.

<Heat and light resistance test>
The obtained single-layer film was cut to a size of 150 mm in the TD direction and 70 mm in the MD direction, pasted on a PTFE sheet of the same size and 0.3 mm thick, and set in a sample holder with an opening of 135 mm width and 55 mm height. did. Using a super xenon weather meter SX75 manufactured by Suga Test Instruments Co., Ltd., ultraviolet rays were continuously irradiated for 48 hours under the conditions of irradiance of 150 W/m ² , black panel temperature of 83° C., and chamber humidity of 50% RH. After the irradiation, the unirradiated portion around the film was cut off to obtain a film sample with a width of 135 mm and a height of 55 mm for the heat and light resistance test.

<Elongation at break>
The obtained single-layer film was cut into a film sample having a size of 150 mm in the TD direction and 70 mm in the MD direction. Cuts were made in advance at 15 mm intervals with a razor blade, and the film sample was irradiated with ultraviolet rays in the same manner as in the above heat and light resistance test. The sample after irradiation with ultraviolet rays was cut into 15 mm width and 50 mm length to prepare a sample for a tensile test, and the sample was conditioned for 5 days at a temperature of 23° C. and a humidity of 50% RH. After humidity conditioning, the sample was subjected to a tensile test in the MD direction using a tensile tester (“AUTOGRAPH AGS-H” manufactured by Shimadzu Corporation) at a distance between chucks of 30 mm and a tensile speed of 500 mm/min with N=5 to determine the elongation at break. Measured (evaluation after heat and light resistance test). Furthermore, the elongation at break was similarly measured for film samples that were not irradiated with ultraviolet rays (evaluation before heat and light resistance test). The reduction rate (%) of the elongation at break after the heat and light resistance test relative to the elongation at break before the heat and light resistance test was calculated. These evaluation results are shown in Tables 3 to 14 and 16.

<Mass loss: accelerated microplasticization test>
Heat and light resistance test Four processed film samples were prepared and vacuum dried at 60°C for 24 hours, and then the total dry mass (W1) of the four film samples before the pulverization process described below was measured. Four film samples after the heat and light resistance test, 500 g of zirconia balls each having a diameter of 3 mm, and 100 mL of deionized water were charged into an alumina ceramic pot mill having a capacity of 300 mL. The hermetically sealed pot mill was installed on a tabletop pot mill stand "PM-001" manufactured by As One Co., Ltd., and was operated at a rotation speed of 200 rpm to carry out the pulverization treatment at room temperature for 4 hours. The contents of the pulverized pot mill were taken out along with water, and deionized water was added thereto, followed by stirring and decantation, which were repeated to separate the zirconia balls from the pulverized material and water. The contents from which the zirconia balls were removed were filtered under reduced pressure through a 46 μm nylon mesh, and the filtrate was vacuum dried at 60°C. The mass (W2) of the crushed material of 46 μm or more that remained after filtering through the nylon mesh was measured, and the mass loss (M) was calculated according to the following formula (i) (evaluation after heat and light resistance test).
M (%)=(W1-W2)/W1×100...(i)
In addition, mass loss was similarly measured for film samples that were not subjected to the ultraviolet irradiation test (evaluation before heat and light resistance test). These evaluation results are shown in Tables 3 to 14 and 16.
The value of mass loss in the evaluation after the heat and light resistance test is used as an index of microplasticization, and the smaller the value, the more suppressed microplasticization can be.

<Retort resistance evaluation test>
[Production of multilayer sheet for retort]
Single-layer films with a thickness of 20 μm of Examples 1 to 7 and Comparative Examples 1 to 5 obtained above, a commercially available biaxially oriented nylon 6 film (“Emblem ON” manufactured by Unitika, thickness 15 μm) and a commercially available Cut unstretched polypropylene films (manufactured by Mitsui Chemicals Tocello, Tocello CP, thickness 60 μm) into A4 size pieces, and coat both sides of the single-layer film with a dry laminating adhesive ("Takelac A-385" (Takeda Pharmaceutical Co., Ltd.)). (manufactured by Takeda Pharmaceutical Co., Ltd.) as the main agent, "Takenate A-50" (manufactured by Takeda Pharmaceutical Co., Ltd.) as the hardening agent, and ethyl acetate as the diluent) was applied at 4.0 g/m, with the outer layer being a nylon 6 film and the inner layer. Dry lamination was carried out so that it became an unstretched polypropylene film, and the obtained laminate film was dried at 80° C. for 3 minutes to evaporate the diluent. Thereafter, it was cured at 40° C. for 3 days to obtain a transparent multilayer sheet consisting of three layers.

[OTR (Oxygen Transmission Rate)]
The single-layer films obtained in Examples 1 to 7 and Comparative Examples 1 to 5 were subjected to humidity conditioning under conditions of 20°C/65% RH, and then tested using an oxygen permeability measuring device (Modern Control's "OX-Tran2/ The oxygen permeability was measured under conditions of 20° C./65% RH. Note that this measurement was conducted in accordance with ISO14663-2 annex C. The measurement results are shown in Table 16.

[Retort resistance evaluation]
Using the obtained multilayer sheet, a pouch with inner dimensions of 12 x 12 cm and sealed on all sides was prepared. The contents were water. This was subjected to retort treatment at 120° C. for 20 minutes using a retort device (manufactured by Hisaka Seisakusho, high temperature and high pressure cooking sterilization tester, RCS-40RTGN). After the retort treatment, the surface water was wiped off and the product was allowed to stand for one day in a high temperature, high humidity room at 20° C. and 65% RH, and then the retort resistance was evaluated based on the following criteria. The evaluation results are shown in Table 16.
(Evaluation criteria for retort resistance)
A (Good): Transparency was ensured. B (Poor): There was whitening in spots.

<Consideration>
As shown in Table 3, the resin composition of Reference Comparative Example 3, which does not contain aluminum ions, has an insufficient effect of suppressing the generation of lumps, and has poor heat and light resistance (reduction rate of elongation at break) and microplastics. The chemical resistance (mass loss in the evaluation after the heat and light resistance test) was also relatively large. On the other hand, the resin composition of Reference Comparative Example 1, which contained a small amount of aluminum ions, tended to be improved compared to the resin composition of Reference Comparative Example 3, but the improvement effect was low. . In addition, the resin composition of Reference Comparative Example 2 containing a large amount of aluminum ions did not have an improved effect of suppressing the generation of lumps. In contrast, each resin composition of Reference Examples 1 to 6 has a content (b) of aluminum ions (B) per 1 g of EVOH (A) in a range of 0.002 μmol/g or more and 0.17 μmol/g or less. It can be seen that the resin composition of Reference Comparative Example 1, which contained a small amount of aluminum ions, was further improved in the effect of suppressing lumps, heat resistance, light resistance, and resistance to microplasticization.

Tables 4-10 are results using other EVOHs. From these results, similarly to the results in Table 3, when the content (b) of aluminum ions (B) per 1 g of EVOH (A) is within the range of 0.002 μmol/g or more and 0.17 μmol/g or less, It can be seen that the effect of suppressing lumps, heat resistance and light resistance, and resistance to forming microplastics are improved.

As shown in Table 3, the improvement effect was insufficient when the content of aluminum ions was low (0.02 ppm, 0.001 μmol/g), so in Tables 4 to 10, aluminum Based on the reference comparative example with an ion content of 0.02 ppm (0.001 μmol/g), those that are improved from this are evaluated as "+", and those that are not improved are evaluated as "-", and these are evaluated as Shown in the table.

On the other hand, as shown in Table 11, if the total content (i + ii) of terminal carboxylic acid units and terminal lactone ring units is too small, even if the content of aluminum ions is adjusted, the The mass loss was 14.0% by mass or more, and the product did not have sufficient resistance to forming microplastics. Furthermore, as shown in Table 12, if the total content (i+ii) of terminal carboxylic acid units and terminal lactone ring units is too large, even if the content of aluminum ions is adjusted, the evaluation will be D. However, the occurrence of pimples could not be sufficiently suppressed.

From the above results, when the total content (i + ii) of terminal carboxylic acid units and terminal lactone ring units per 1 g of EVOH (A) is within the range of 14 μmol/g to 78 μmol/g, per 1 g of EVOH (A) By setting the content (b) of aluminum ions (B) within the range of 0.002 μmol/g or more and 0.17 μmol/g or less, the generation of lumps during melt molding is suppressed, and sufficient heat and light resistance is achieved. It can be seen that this is a resin composition that can be used to obtain a molded article that does not easily turn into microplastics after disposal, and that has sufficiently improved each of the above characteristics compared to a resin composition that uses the same EVOH. .

In addition, as shown in Table 13, by further containing at least one compound selected from the group consisting of cinnamic acids and conjugated polyene compounds with a molecular weight of 1,000 or less in addition to aluminum ions, heat and light resistance and microplastics can be improved. It can be seen that the corrosion resistance is further improved.

As shown in Table 14, when comparing Reference Example 8 and Reference Example 34, in which almost the same EVOH was used except for the lactone ring unit ratio, Reference Example 8, in which EVOH-B with a high lactone ring unit ratio was used, was It can be seen that the material has high heat resistance, light resistance, and microplasticization resistance.

Furthermore, as shown in Tables 15 and 16, the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of EVOH (A) is 14 μmol/g or more and 78 μmol/g or less. , the content (b) of aluminum ions (B) per 1 g of EVOH (A) is within the range of 0.002 μmol/g or more and 0.17 μmol/g or less, and polyamide (D) and specific metal atoms ( When E) is contained in a predetermined content, in addition to improving the lump suppression effect, heat resistance and light resistance, and resistance to microplasticization, gas barrier properties (OTR) and retort resistance (hot water or Good results were also obtained in that the occurrence of appearance defects after heat treatment with water vapor was suppressed.

In addition, in Table 16, regarding the effect of suppressing lumps, heat resistance, light resistance, and resistance to microplasticization, Comparative Example 1 in Table 16 is used as the standard, and those that are improved are marked as "+", and those that are not improved are marked as "+". These were evaluated as "-" and are shown in Table 16. However, from the comparison between Comparative Examples 1 and 2 and Example 1 in Table 16, by adjusting the content (b) of aluminum ions (B), compared to those using the same type of EVOH, It can also be confirmed that the resin compositions of each example have an improved effect of suppressing lumps, heat resistance, light resistance, and microplasticization resistance.

Furthermore, in addition to the resin compositions of Examples 1 to 7, for example, by mixing a predetermined amount of polyamide (D) and metal atoms (E) to the resin compositions of Reference Examples 1 to 34, the resin compositions of the present invention can be prepared. The composition can be prepared, and such resin compositions also suppress the generation of lumps during melt molding, have sufficient heat and light resistance, and are micro-resistant after disposal. It is clear that this resin composition yields a molded article that is difficult to be made into plastic, and that the above characteristics are sufficiently improved compared to those using the same EVOH. Therefore, even if the resin composition contains EVOH (A), aluminum ion (B), polyamide (D), and metal atom (E) other than the resin compositions of Examples 1 to 7, the carbon Using EVOH (A) in which the total content (i + ii) of acid units (I) and lactone ring units (II) is 14 μmol/g or more and 78 μmol/g or less, the amount of aluminum ions (B) per 1 g of EVOH (A) is By adjusting the content (b) within the range of 0.002 μmol/g or more and 0.17 μmol/g or less, and keeping the content of polyamide (D) and metal atom (E) within the specified range, the appearance of bumps can be suppressed. It is considered that the results of Reference Examples 1 to 34 sufficiently demonstrate that the effect, heat resistance, light resistance, and microplasticization resistance are improved.

The resin composition of the present invention is useful as a molding material for various molded objects.

Claims (9)

A resin composition containing an ethylene-vinyl alcohol copolymer (A), an aluminum ion (B), a polyamide (D), and at least one metal atom (E) selected from the group consisting of magnesium, calcium, and zinc. There it is,
At least a part of the ethylene-vinyl alcohol copolymer (A) has at least one of a carboxylic acid unit (I) and a lactone ring unit (II) located at the end of the polymer,
The total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) per 1 g of ethylene-vinyl alcohol copolymer (A) is 14 μmol/g or more and 78 μmol/g or less,
The content (b) of aluminum ions (B) per 1 g of ethylene-vinyl alcohol copolymer (A) is 0.002 μmol/g or more and 0.17 μmol/g or less,
The mass ratio (D/A) of the polyamide (D) to the ethylene-vinyl alcohol copolymer (A) is 5/95 or more and 40/60 or less,
A resin composition in which the content (e) of metal atoms (E) in the ethylene-vinyl alcohol copolymer (A) is 1 ppm or more and 500 ppm or less in terms of metal elements. The ratio ((i+ii)/b) of the total content (i+ii) of carboxylic acid units (I) and lactone ring units (II) to the content (b) of aluminum ions (B) is 180 or more and 20,000 or less The resin composition according to claim 1. The resin composition according to claim 1 or 2, wherein the aluminum ion (B) is derived from a fatty acid aluminum salt having 5 or less carbon atoms. further containing at least one compound (C) selected from the group consisting of cinnamic acids and conjugated polyene compounds with a molecular weight of 1,000 or less,
The resin composition according to any one of claims 1 to 3, wherein the content (c) of the compound (C) relative to the ethylene-vinyl alcohol copolymer (A) is 1 ppm or more and 1,000 ppm or less. A claim in which the ratio (ii/(i+ii)) of the content (ii) of the lactone ring unit (II) to the total content (i+ii) of the carboxylic acid unit (I) and the lactone ring unit (II) is 40 mol% or more The resin composition according to any one of items 1 to 4. A molded article formed from the resin composition according to any one of claims 1 to 5. A multilayer structure comprising a layer made of the resin composition according to any one of claims 1 to 5. A container comprising the multilayer structure according to claim 7. The container according to claim 8, which is used for boil sterilization or retort sterilization.

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