Ethylene-vinyl alcohol copolymer resin composition, method for producing the same, and molded article, multilayer structure, and masterbatch containing the resin composition

Abstract

To provide a resin composition which is excellent in gas barrier properties, piercing strength and light stability and a method for producing the same, and a molding, a multilayer structure and a master batch which include the resin composition.SOLUTION: A resin composition contains an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less, a fluorine-based polymer (B) and aldehyde (C), wherein the aldehyde (C) is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb), the content of the fluorine-based polymer (B) is 10 ppm or more and 50,000 ppm or less, and the content of the aldehyde (C) is 0.005 ppm or more and 13 ppm or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition containing an ethylene-vinyl alcohol copolymer and a fluorine-based polymer, a method for producing the same, and a molded article and a multilayer structure containing the resin composition, and a masterbatch of the resin composition. [Background technology]

[0002] Packaging materials for long-term food storage are often required to have gas barrier properties, including oxygen barrier properties. By using packaging materials with high gas barrier properties, it is possible to suppress oxidative deterioration of food caused by oxygen intrusion and the proliferation of microorganisms. Metal foils such as aluminum and inorganic vapor deposition layers such as silicon oxide and aluminum oxide are widely used as layers that improve gas barrier properties. On the other hand, resin layers with gas barrier properties such as vinyl alcohol polymers and polyvinylidene chloride are also widely used. Vinyl alcohol polymers have the characteristic of exhibiting gas barrier properties by crystallizing and densifying due to hydrogen bonding between hydroxyl groups in the molecules. Among them, ethylene-vinyl alcohol copolymers (hereinafter sometimes abbreviated as "EVOH") are suitable for melt molding due to their excellent thermal stability, and with the development of coextrusion technology, multilayer films with an EVOH layer as an intermediate layer are widely used as gas barrier packaging materials.

[0003] In recent years, environmental and waste problems have led to a worldwide demand for post-consumer recycling (hereinafter sometimes abbreviated as recycling), which involves collecting and recycling packaging materials consumed in the market. In recycling, the collected packaging materials are generally cut into pieces, separated and washed as necessary, and then melt-mixed using an extruder. In this regard, packaging materials are required to be composed of a single material as much as possible (mono-materialization), which allows for the production of high-purity, high-quality recycled raw materials. For this purpose, there is an increasing demand for barrier films made mainly of polyolefins, which are widely used as packaging materials. However, since polyolefins have poor compatibility with polyamides and the like, which deteriorates recyclability, it is not desirable to provide a polyamide layer on a barrier film made mainly of polyolefins, while barrier films without a polyamide layer have the problem of insufficient mechanical strength.

[0004] As a means for solving such problems, Patent Document 1 describes a multilayer film having a hard layer with a puncture strength of 40 N / mm or more and 150 N / mm or less, and (1) a resin composition layer having an EVOH having a melting point of 170°C or more and an EVOH having a melting point of less than 170°C, or (2) a resin composition layer having a modified EVOH that contains a modifying group with a specific primary hydroxyl group. Although such a multilayer film does not have a polyamide layer, it is excellent in mechanical strength and thermoformability, and when the recovered material is melt-molded, the generation of bumps due to deterioration (gelation) of the resin is suppressed, and it is also excellent in recyclability.

[0005] Furthermore, Patent Document 2 describes that a film using EVOH pellets containing EVOH and a plurality of fluorine-containing fine particles, the fluorine-containing fine particles having a particle diameter with a major axis length of less than 20 μm, has excellent mechanical strength. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 071513 [Patent Document 2] JP 2021-119212 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in recent years, the layer configurations of multilayer structures used in packaging materials have become increasingly diverse, and an embodiment in which the layer configuration is limited, such as the multilayer film described in Patent Document 1, may not be preferable, and even the multilayer film described in Patent Document 1 may have insufficient mechanical strength, such as puncture strength, and there has been a demand for improving the puncture strength of the EVOH layer itself. In addition, when the EVOH pellets described in Patent Document 2 are used, the puncture strength of the EVOH layer itself can be improved, but when the film is displayed on shelves in supermarkets and the like for a long period of time as a food packaging material, coloring of the film due to fluorescent light may become a problem.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide a resin composition having excellent gas barrier properties, puncture strength and light stability, a method for producing the same, and a molded article, a multilayer structure and a masterbatch containing the resin composition. [Means for solving the problem]

[0009] According to the present invention, the above object is [1] A resin composition comprising an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less, a fluorine-based polymer (B) and an aldehyde (C), wherein the aldehyde (C) is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb), the content of the fluorine-based polymer (B) is 10 ppm or more and 50,000 ppm or less, and the content of the aldehyde (C) is 0.005 ppm or more and 13 ppm or less; [2] The resin composition according to [1], wherein the content of 2,4-hexadienal (Ca) is 0.005 ppm or more and 10.0 ppm or less, and the content of 2,4,6-octatrienal (Cb) is 0.005 ppm or more and 5.00 ppm or less; [3] The resin composition according to [1] or [2], in which (Ca+Et / 100) / Cb≦2.0, where Et is the ethylene unit content of the ethylene-vinyl alcohol copolymer (A), Ca is the 2,4-hexadienal (Ca) content (ppm), and Cb is the 2,4,6-octatrienal (Cb) content (ppm); [4] The resin composition according to any one of [1] to [3], in which, when the ethylene unit content of the ethylene-vinyl alcohol copolymer (A) is Et, the content of 2,4-hexadienal (Ca) is Ca (ppm), and the content of 2,4,6-octatrienal (Cb) is Cb (ppm), Et / 100+Ca+Cb≦6.50; [5] The resin composition according to any one of [1] to [4], containing a boron compound in an amount of 50 ppm or more and 400 ppm or less, calculated as boron element; [6] The resin composition according to any one of [1] to [5], containing a metal element (D) of Group 6 of the periodic table at 0.005 ppb or more and 50 ppb or less; [7] The resin composition of any one of [1] to [6], wherein the melting point of the fluorine-based polymer (B) is 100 to 200°C; [8] The resin composition of any one of [1] to [7], wherein the melt flow rate of the fluoropolymer (B) at 230°C under a load of 10.9 kg, as measured in accordance with JIS K 7210-1 (2014), is 2.0 to 50 g / 10 min; [9] A molded article comprising the resin composition according to any one of [1] to [8];

[10] A multilayer structure having at least one layer made of the resin composition according to any one of [1] to [8];

[11] A multilayer structure having a layer made of any one of the resin compositions according to [1] to [8] as an outermost layer;

[12] A masterbatch comprising an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less, a fluorine-based polymer (B) and an aldehyde (C), wherein the aldehyde (C) is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb), the content of the fluorine-based polymer (B) is 10,000 ppm or more and 200,000 ppm or less, and the content of the aldehyde (C) is 0.05 ppm or more and 130 ppm or less;

[13] A method for producing the resin composition according to any one of [1] to [8], comprising a step of dry-blending and melt-kneading pellets containing an ethylene-vinyl alcohol copolymer (A) and an aldehyde (C) with pellets containing a fluorine-based polymer (B);

[14] A method for producing a resin composition according to any one of [1] to [8], comprising a step of dry-blending and melt-kneading the masterbatch of

[12] with pellets containing an ethylene-vinyl alcohol copolymer (A); This is achieved by providing Effect of the Invention

[0010] According to the present invention, there are provided a resin composition having excellent gas barrier properties, puncture strength and light stability, a method for producing the same, a molded article containing the resin composition, a multilayer structure, and a masterbatch of the resin composition. Here, "light stability" refers to the property of being able to suppress coloration even when exposed to light, and specifically, can be evaluated by the method described in the Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The resin composition of the present invention is a resin composition containing EVOH (A), a fluorine-based polymer (B), and an aldehyde (C), in which the aldehyde (C) is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb), and contains 10 ppm to 50,000 ppm of the fluorine-based polymer (B) and 0.005 ppm to 13 ppm of the aldehyde (C). When the resin composition of the present invention contains a specific amount of the fluorine-based polymer (B), the puncture strength tends to be improved, but the resin composition tends to become discolored when exposed to light such as a fluorescent lamp for a long period of time. However, when the resin composition of the present invention contains a specific amount of the fluorine-based polymer (B) and the aldehyde (C), it surprisingly tends to improve the puncture strength while suppressing discoloration when exposed to light such as a fluorescent lamp for a long period of time.

[0012] [EVOH(A)] The resin composition of the present invention contains EVOH (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less. The resin composition of the present invention can exhibit good gas barrier properties by containing EVOH (A). EVOH (A) is a copolymer having ethylene units and vinyl alcohol units, and is obtained, for example, by saponifying a copolymer containing ethylene and a vinyl ester using an alkali catalyst or the like. A representative vinyl ester is vinyl acetate, but other fatty acid vinyl esters (vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc.) can also be used.

[0013] The lower limit of the ethylene unit content of EVOH (A) is 20 mol%, preferably 23 mol%, and more preferably 25 mol%. The upper limit of the ethylene unit content of EVOH (A) is 60 mol%, preferably 55 mol%, and more preferably 50 mol%. If the ethylene unit content is less than the lower limit, the melt moldability of the resin composition may be reduced. Conversely, if the ethylene unit content exceeds the upper limit, the gas barrier property may be reduced. The ethylene unit content of EVOH (A) is1 It can be determined by H-NMR measurement.

[0014] The lower limit of the saponification degree of EVOH (A) is preferably 90 mol%, more preferably 95 mol%, and even more preferably 99 mol%. When the saponification degree of EVOH (A) is equal to or higher than the lower limit, the gas barrier properties of the resulting laminate or the like are improved. The saponification degree means the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in EVOH (A). The upper limit of the saponification degree may be 99.99 mol%. The saponification degree of EVOH (A) is 1 It can be determined by H-NMR measurement.

[0015] EVOH (A) may contain other monomer units other than ethylene, vinyl ester and vinyl alcohol, so long as the effects of the present invention are not impaired. In particular, by introducing a modified group containing a primary hydroxyl group having a specific structure, it may be possible to achieve a high level of both gas barrier properties and moldability of EVOH (A). The content of other monomer units is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and particularly preferably substantially none. Examples of such other monomers include alkenes such as propylene, butylene, pentene, and hexene; 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-methyl-1-butene, 4-acyloxy-1-butene, 3,4-diacyloxy-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-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diacyloxy-1-pentene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy-1-hexene, 5,6-diacyloxy ester group-containing alkenes or saponification products thereof, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, or other unsaturated acids or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids or salts thereof, such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid; vinyl silane compounds such as vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tri(β-methoxy-ethoxy) silane, and γ-methacryloxypropyl methoxy silane; alkyl vinyl ethers, vinyl ketones, N-vinyl pyrrolidone, vinyl chloride, and vinylidene chloride.

[0016] EVOH (A) may be modified as necessary by urethanization, acetalization, cyanoethylation, oxyalkylenation, etc. Oxyalkylenation can be carried out using an epoxy compound, such as 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, Examples of such epoxy alkanols include 2-epoxyoctane, 2,3-epoxyoctane, 1,2-epoxynonane, 2,3-epoxynonane, 1,2-epoxydecane, 1,2-epoxydodecane, epoxyethylbenzene, 1-phenyl-1,2-propane, 3-phenyl-1,2-epoxypropane, various alkyl glycidyl ethers, various alkylene glycol monoglycidyl ethers, various alkenyl glycidyl ethers, various epoxy alkanols such as glycidol, various epoxy cycloalkanes, and various epoxy cycloalkenes. Among these, 1,2-epoxybutane, 2,3-epoxybutane, epoxypropane, epoxyethane, or glycidol is preferred, and epoxypropane or glycidol is more preferred.

[0017] The melt flow rate (MFR) of EVOH (A) (190°C, under a load of 2160 g) is preferably 0.1 to 30 g / 10 min, more preferably 0.3 to 25 g / 10 min, and even more preferably 0.5 to 20 g / 10 min. However, for those having a melting point near or exceeding 190°C, the MFR is measured under a load of 2160 g at multiple temperatures equal to or higher than the melting point, and is plotted on a semi-logarithmic graph with the reciprocal of absolute temperature on the horizontal axis and the logarithm of MFR on the vertical axis, and expressed as a value extrapolated to 190°C.

[0018] The EVOH (A) may be used alone or in combination of two or more kinds.

[0019] [Fluoropolymer (B)] The resin composition of the present invention contains 10 ppm or more and 50000 ppm or less of fluoropolymer (B). The resin composition of the present invention tends to improve the pin puncture strength by containing fluoropolymer (B), and the pin puncture strength is improved by using it in combination with aldehyde (C) described later. The lower limit of the content of fluoropolymer (B) is preferably 50 ppm, more preferably 100 ppm. On the other hand, the upper limit of the content of aldehyde (C) is preferably 10000 ppm, more preferably 5000 ppm, further preferably 1000 ppm, and particularly preferably 800 ppm. If the content of fluoropolymer (B) is less than 10 ppm, the light stability tends to be insufficient. On the other hand, if the content of fluoropolymer (B) is more than 50000 ppm, the pin puncture strength of the film becomes insufficient and the transparency also decreases.

[0020] The fluoropolymer (B) is not particularly limited as long as it has fluorine atoms, and any known polymer can be used. From the viewpoint of further improving the pin puncture strength, the fluoropolymer (B) preferably contains at least one monomer unit selected from the group consisting of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene. The fluoropolymer (B) may be a homopolymer consisting of the monomer units, or may be a copolymer having the monomer units, but is more preferably a copolymer of vinylidene fluoride and hexafluoropropylene. In the copolymer of vinylidene fluoride and hexafluoropropylene, the ratio of hexafluoropropylene is increased to obtain a fluoropolymer having a low melting point.

[0021] As the fluorine-based polymer (B), commercially available products can be used, such as Kynar Flex (trademark) 2500-20 (manufactured by Arkema Co., Ltd.), Kynar Flex (trademark) 2801 (manufactured by Arkema Co., Ltd.), Kynar Flex (trademark) 2821 (manufactured by Arkema Co., Ltd.), Kynar Flex (trademark) 2501 (manufactured by Arkema Co., Ltd.), Kynar Flex (trademark) 3121-50 (manufactured by Arkema Co., Ltd.), Dynamer (trademark) FX 5911 (manufactured by 3M Japan Co., Ltd.), Dynamer (trademark) FX 5920A (manufactured by 3M Japan Co., Ltd.), Dynamer (trademark) FX 9613 (manufactured by 3M Japan Co., Ltd.), DA-3105T (manufactured by Daikin Industries, Ltd.), DA-810X (manufactured by Daikin Industries, Ltd.), and DA-910 (manufactured by Daikin Industries, Ltd.), and particularly preferred is Kynar Flex (trademark).

[0022] The fluoropolymer (B) preferably has a melting point of 100 to 200° C. The lower limit of the melting point is more preferably 110° C., and even more preferably 120° C. The upper limit of the melting point is more preferably 180° C., and even more preferably 160° C. When the melting point is within the above range, the dispersibility of the fluoropolymer (B) in the EVOH (A) becomes good, and the pin puncture strength is improved.

[0023] In addition, the fluoropolymer (B) preferably has an MFR of 2.0 to 50 g / 10 min at 230° C. under a load of 10.9 kg, measured in accordance with JIS K 7210-1 (2014). The lower limit of the MFR is more preferably 5.0 g / 10 min, further preferably 10.0 g / 10 min, and particularly preferably 15.0 g / 10 min. The upper limit of the MFR is more preferably 45.0 g / 10 min, and further preferably 40.0 g / 10 min. When the melt flow rate is within the above range, the dispersibility of the fluoropolymer (B) in the EVOH (A) is good, and the pin puncture strength is stable.

[0024] [Aldehyde (C)] The resin composition of the present invention contains 0.005 ppm or more and 13 ppm or less of aldehyde (C), which is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb). The resin composition of the present invention tends to have excellent pin puncture strength and light stability by containing a specific amount of aldehyde (C) while containing a specific amount of fluoropolymer. That is, the combination of fluoropolymer (B) and aldehyde (C) produces a new effect of improving pin puncture strength. In addition, the problem of film coloration after light irradiation caused by the inclusion of fluoropolymer (B) can be improved by aldehyde (C).

[0025] The lower limit of the content of aldehyde (C) in the resin composition of the present invention is preferably 0.01 ppm, more preferably 0.1 ppm, and even more preferably 0.5 ppm. On the other hand, the upper limit of the content of aldehyde (C) is preferably 10 ppm, more preferably 6 ppm, and even more preferably 2 ppm. If the content of aldehyde (C) is less than 0.005 ppm, the film tends to become discolored when exposed to light such as fluorescent light for a long period of time. On the other hand, if the content of aldehyde (C) is more than 13 ppm, the film immediately after film formation becomes discolored.

[0026] In one embodiment, the resin composition of the present invention may contain 0.005 ppm or more and 10.0 ppm or less of 2,4-hexadienal (Ca) as the aldehyde (C). When the resin composition of the present invention contains 2,4-hexadienal (Ca), the lower limit of the content of 2,4-hexadienal (Ca) is preferably 0.01 ppm, more preferably 0.05 ppm, and even more preferably 0.75 ppm. On the other hand, the upper limit of the content of 2,4-hexadienal (Ca) is preferably 5 ppm, more preferably 1.2 ppm, and even more preferably 1 ppm. When the content of 2,4-hexadienal (Ca) is 0.005 ppm or more, the light stability tends to be excellent. On the other hand, when the content of 2,4-hexadienal (Ca) is 10 ppm or less, the film immediately after film formation tends to be suppressed from being colored.

[0027] In one embodiment, the resin composition of the present invention may contain 2,4,6-octatrienal (Cb) in an amount of 0.005 ppm or more and 5.00 ppm or less. When the resin composition of the present invention contains 2,4,6-octatrienal (Cb), the lower limit of the content of 2,4,6-octatrienal (Cb) is preferably 0.1 ppm, more preferably 0.25 ppm, and even more preferably 0.5 ppm. On the other hand, the upper limit of the content of 2,4,6-octatrienal (Cb) is preferably 5 ppm, more preferably 2 ppm, and even more preferably 1 ppm. When the content of 2,4,6-octatrienal (Cb) is 0.005 ppm or more, the light stability tends to be excellent. On the other hand, when the content of 2,4,6-octatrienal (Cb) is 5 ppm or less, the coloring of the film immediately after film formation tends to be suppressed.

[0028] The resin composition of the present invention preferably contains 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb) from the viewpoint of superior pin puncture strength and light stability.

[0029] In the resin composition of the present invention, from the viewpoint of suppressing coloration of the film, it is preferable that (Ca+Et / 100) / Cb≦2.0, where Et is the ethylene unit content of EVOH (A), Ca is the 2,4-hexadienal (Ca) content (ppm), and Cb is the 2,4,6-octatrienal (Cb) content (ppm).

[0030] In the resin composition of the present invention, from the viewpoint of suppressing coloration of the film, it is preferable that Et / 100+Ca+Cb≦6.50, where Et is the ethylene unit content of EVOH (A), Ca is the 2,4-hexadienal (Ca) content (ppm), and Cb is the 2,4,6-octatrienal (Cb) content (ppm).

[0031] [Metal elements in group 6 of the periodic table (D)] The resin composition of the present invention preferably contains 0.005 ppb or more and 50 ppb or less of a metal element (D) of Group 6 of the periodic table. By containing the metal element (D) of Group 6 of the periodic table, the resin composition of the present invention tends to be able to suppress adhesion of dirt to the take-up roll during film formation. From the viewpoint of suppressing adhesion of dirt to the take-up roll, the metal element (D) of Group 6 of the periodic table is preferably at least one selected from the group consisting of chromium, molybdenum, and tungsten, more preferably at least one selected from the group consisting of molybdenum and tungsten, and even more preferably tungsten.

[0032] The lower limit of the content of the metal element (D) of Group 6 of the periodic table is more preferably 0.05 ppb, further preferably 0.1 ppb, and particularly preferably 1 ppb. The upper limit of the content of the metal element (D) of Group 6 of the periodic table is more preferably 30 ppb, further preferably 20 ppb, and particularly preferably 10 ppb. When the content of the metal element (D) of Group 6 of the periodic table is within the above range, there is a tendency that the adhesion of dirt to the take-up roll can be prevented while suppressing coloration of the film.

[0033] [Resin composition] The resin composition of the present invention may contain other optional components other than EVOH (A), fluorine-based polymer (B) and aldehyde (C), such as boron compounds, carboxylic acids, phosphorus compounds, metal ions, antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, heat stabilizers, and other resins other than EVOH (A). The resin composition of the present invention may contain two or more of these components. When the resin composition of the present invention contains other optional components, the upper limit of the total content is preferably 1 mass%, and in some cases, 0.5 mass%.

[0034] The resin composition of the present invention preferably contains a boron compound as another component. This can increase the pin puncture strength of the resulting film. The boron compound is not particularly limited, and examples thereof include boric acids, boric acid esters, borate salts, boron hydrides, and the like. Specifically, examples of boric acids include orthoboric acid, metaboric acid, tetraboric acid, and the like, examples of borate esters include triethyl borate, trimethyl borate, and the like, and examples of borates include alkali metal salts, alkaline earth metal salts, borax, and the like of the above-mentioned various boric acids. Among these compounds, orthoboric acid (hereinafter, sometimes simply referred to as boric acid) is preferred. The content of the boron compound is preferably 50 ppm or more and 400 ppm or less in terms of boron element. If the content of the boron compound is 50 ppm or more, the melt moldability tends to be stable, and is more preferably 70 ppm or more, and even more preferably 100 ppm or more. On the other hand, if the content of the boron compound is 400 ppm or less, there is a tendency that deterioration of moldability can be suppressed, and it is more preferably 350 ppm or less, and may be 300 ppm or less.

[0035] The carboxylic acid prevents the resin composition and thus the molded body from being colored, and suppresses gelation during melt molding. Examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, lactic acid, and salts thereof. The carboxylic acid is preferably a carboxylic acid having 4 or less carbon atoms or a saturated carboxylic acid, and more preferably an acetic acid. The acetic acid includes acetic acid and an acetate salt. As the acetic acid, it is preferable to use acetic acid and an acetate salt in combination, and it is more preferable to use acetic acid and sodium acetate in combination. When the resin composition of the present invention includes a carboxylic acid, the lower limit of the content of the carboxylic acid is preferably 50 ppm, more preferably 80 ppm, and even more preferably 120 ppm. In addition, the upper limit of the content of the carboxylic acid is preferably 1,000 ppm, more preferably 500 ppm, and even more preferably 400 ppm. By setting the content of the carboxylic acid to be equal to or more than the above lower limit, a sufficient coloring suppression effect can be obtained, and the occurrence of yellowing can be sufficiently suppressed. On the other hand, by setting the content of carboxylic acids to the above upper limit or less, gelation is less likely to occur during melt molding, particularly during long-term melt molding, and the appearance of the molded product and the like is improved.

[0036] The phosphorus compound suppresses the occurrence of defects such as streaks and fish eyes, and coloring, and improves long-run properties. Examples of the phosphorus compound include phosphates such as phosphoric acid and phosphorous acid. The phosphate may be in the form of primary phosphate, secondary phosphate, or tertiary phosphate. The cationic species of the phosphate is not particularly limited, but is preferably an alkali metal salt or an alkaline earth metal salt, and among these, compounds containing phosphate ions such as sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate are more preferred, and sodium dihydrogen phosphate and dipotassium hydrogen phosphate are even more preferred. When the resin composition of the present invention contains a compound containing phosphate ions as a phosphorus compound, the lower limit of the content of the phosphate ions is preferably 5 ppm, more preferably 10 ppm, even more preferably 20 ppm, and particularly preferably 30 ppm. The upper limit of the content of the phosphorus compound relative to EVOH (A) is preferably 200 ppm, more preferably 150 ppm, and even more preferably 100 ppm. By setting the content of the phosphorus compound to be equal to or more than the above lower limit or equal to or less than the above upper limit, the thermal stability is improved, and the generation of gel-like particles, coloration, etc. during long-term melt molding is less likely to occur.

[0037] Examples of the metal ion include monovalent metal ions, divalent metal ions, and other transition metal ions, and these may be composed of one or more kinds. Among them, monovalent metal ions and divalent metal ions are preferred. As the monovalent metal ion, an alkali metal ion is preferred, for example, an ion of lithium, sodium, potassium, rubidium, and cesium, and from the viewpoint of industrial availability, an ion of sodium or potassium is preferred. In addition, examples of the alkali metal salt that gives the alkali metal ion include an aliphatic carboxylate, an aromatic carboxylate, a carbonate, a hydrochloride, a nitrate, a sulfate, a phosphate, and a metal complex. Among them, an aliphatic carboxylate and a phosphate are preferred from the viewpoint of availability, and specifically, sodium acetate, potassium acetate, sodium phosphate, and potassium phosphate are preferred. In some cases, it is preferred to include a divalent metal ion as the metal ion. When the metal ion includes a divalent metal ion, for example, thermal deterioration of EVOH when trim is recovered and reused may be suppressed, and the occurrence of gels and bumps in the obtained molded body may be suppressed. Examples of divalent metal ions include beryllium, magnesium, calcium, strontium, barium, and zinc ions, and magnesium, calcium, or zinc ions are preferred from the viewpoint of industrial availability. Examples of divalent metal salts that provide divalent metal ions include carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, and metal complexes, and carboxylates are preferred. Examples of carboxylic acids that constitute carboxylates include carboxylic acids having 1 to 30 carbon atoms, and specifically include acetic acid, propionic acid, butyric acid, stearic acid, lauric acid, montanic acid, behenic acid, octanoic acid, sebacic acid, ricinoleic acid, myristic acid, palmitic acid, and the like, and among these, acetic acid and stearic acid are preferred. When the resin composition of the present invention contains an alkali metal ion, the lower limit of the content of the alkali metal ion is preferably 10 ppm, more preferably 100 ppm, and even more preferably 150 ppm. On the other hand, the upper limit of the content of the alkali metal ion is preferably 400 ppm, and more preferably 350 ppm. When the content of alkali metal ions is at least the above lower limit, the interlayer adhesion of the resulting multilayer structure tends to be good.On the other hand, when the content of metal ions is equal to or less than the upper limit, the coloring resistance tends to be good.

[0038] Examples of the antioxidant include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis(6-t-butylphenol), 2,2'-methylene-bis(4-methyl-6-t-butylphenol), octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, etc. Examples of the ultraviolet absorber include ethylene-2-cyano-3,3'-diphenylacrylate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-oxybenzophenone, etc.

[0039] Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester, etc. Examples of the antistatic agent include pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, polyethylene glycol (trade name: Carbowax), etc.

[0040] Examples of the lubricant include ethylene bisstearamide and butyl stearate. Examples of the colorant include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and red iron oxide. Examples of the filler include glass fiber, wollastonite, calcium silicate, talc, and montmorillonite. Examples of the heat stabilizer include hindered phenol compounds and hindered amine compounds.

[0041] Examples of the resin other than EVOH (A) include polyamide and polyolefin.

[0042] In the resin composition of the present invention, the proportion of EVOH (A), fluorine-based polymer (B) and aldehyde (C) is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and particularly preferably 99% by mass or more. The resin composition of the present invention may be substantially composed of only EVOH (A), fluorine-based polymer (B) and aldehyde (C), and the resin composition of the present invention may be composed of only EVOH (A), fluorine-based polymer (B) and aldehyde (C). In this specification, "consisting essentially of" means that optional components can be contained within a range that does not affect the effects of the present invention, and "consisting only of" means that optional components other than impurities that are inevitably contained are excluded.

[0043] The method for producing the resin composition of the present invention is not particularly limited, and for example, the resin composition can be produced by mixing and melt-kneading EVOH (A), fluoropolymer (B), aldehyde (C), and various additives such as the above-mentioned other components as necessary. Specifically, the melt-kneading can be carried out using a known mixing or kneading device such as a kneader-ruder, an extruder, a mixing roll, or a Banbury mixer. The temperature during melt-kneading is usually 110 to 300°C. Various additives such as the above-mentioned other components may be contained in EVOH (A) in advance. The method for pre-containing the additives in EVOH (A) is not particularly limited, and for example, various additives can be pre-containing EVOH (A) by immersing EVOH (A) pellets in a solution containing various additives and drying them.

[0044] In the method for producing the resin composition of the present invention, it is preferable to produce the resin composition of the present invention by preparing pellets in which EVOH (A) and aldehyde (C) are mixed in advance, and dry blending the obtained pellets with pellets containing a fluoropolymer (B), melt-kneading, and pelletizing them. There is no particular limitation on the method for premixing EVOH (A) and aldehyde (C), but for example, aldehyde (C) is added to a solution in which EVOH (A) is dissolved to obtain a solution containing EVOH (A) and aldehyde (C), and the solution is precipitated in a precipitation bath in the form of strands and cut, thereby producing pellets in which EVOH (A) and aldehyde (C) are premixed in advance.

[0045] In addition, from the viewpoint of further increasing the pin puncture strength, the manufacturing method of the present invention preferably includes a step of going through a master batch. As the master batch, it is preferable to use a master batch containing EVOH (A), a fluorine-based polymer (B) and an aldehyde (C), in which the content of the fluorine-based polymer is 10000 ppm or more and 200000 ppm or less, and the content of the aldehyde (C) is 0.05 ppm or more and 3000 ppm or less. Such a master batch can be produced by the same method as the above-mentioned resin composition. As the step of going through a master batch, a manufacturing method including a step of melt-kneading the master batch and a pellet containing EVOH (A) is preferable. By providing a step of going through a master batch, the fluorine-based polymer (B) and the aldehyde (C) are better dispersed in the EVOH (A) than other mixing methods, and the pin puncture strength tends to be more excellent. The EVOH (A) contained in the master batch and the EVOH (A) used when further melt-kneading the master batch may be the same or different.

[0046] [Master batch] A masterbatch used in a method for producing a resin composition including a process of the above-mentioned masterbatch is also an embodiment of the present invention. The masterbatch of the present invention contains EVOH (A), fluoropolymer (B) and aldehyde (C) at a high concentration, and is used by diluting with EVOH (A) at a specified ratio when producing the resin composition of the present invention. The masterbatch of the present invention contains EVOH (A), fluoropolymer (B) and aldehyde (C), and contains 10000 ppm or more and 200000 ppm or less of fluoropolymer (B) and 0.05 ppm or more and 130 ppm or less of aldehyde (C). When the contents of the fluoropolymer (B) and aldehyde (C) are within the above-mentioned ranges, the masterbatch can be stably produced.

[0047] [Molded body] The resin composition of the present invention can be formed into a molded article such as a film, sheet, tube, bag, or bottle by melt molding or the like. The molded article of the present invention may have a portion formed from the resin composition of the present invention. That is, the molded article of the present invention may be a molded article consisting of only the resin composition of the present invention, or may be a molded article consisting of a portion consisting of only the resin composition of the present invention and other portions. In this specification, a film usually means a material having a thickness of less than 300 μm, and a sheet usually means a material having a thickness of 300 μm or more. Examples of the melt molding method include extrusion molding, cast molding, inflation extrusion molding, blow molding, melt spinning, injection molding, injection blow molding, and co-extrusion blow molding. The melt molding temperature varies depending on the melting point of EVOH (A), and is preferably about 150 to 270° C. These molded articles can be pulverized and molded again for the purpose of reuse. In addition, films, sheets, etc. can be uniaxially or biaxially stretched.

[0048] The films and sheets (hereinafter sometimes abbreviated as "films, etc.") formed from the resin composition of the present invention include single-layer films, etc. and multi-layer films, etc. The films, etc. can be used as various packaging materials, etc.

[0049] The film or the like can be produced by the same method as that shown for producing the above-mentioned molded article. Among them, a method including a cast molding step of melt-extruding the resin composition of the present invention onto a casting roll, and a step of stretching the non-stretched film obtained from the resin composition of the present invention (a uniaxial stretching step, a sequential biaxial stretching step, a simultaneous biaxial stretching step, an inflation molding step, etc.) is preferred. According to such a method for producing a film or the like, by including these steps, the break resistance can be improved.

[0050] [Multilayer structure] The multilayer structure of the present invention has at least one layer (hereinafter also referred to as "barrier layer") made of the resin composition of the present invention, and has layers made of other components. The multilayer structure has advantages such as improved functionality compared to a molded product having a single layer structure. The lower limit of the number of layers in the multilayer structure may be 2 layers or 3 layers. The upper limit of the number of layers in the multilayer structure may be 1000 layers, 100 layers, or 10 layers. The multilayer structure of the present invention may further have a layer formed from a component other than a resin, such as a layer formed from paper, a metal layer, etc.

[0051] As the layer consisting of other components, a thermoplastic resin layer formed from a thermoplastic resin is preferred. The layer structure of the multilayer structure of the present invention is not particularly limited, and examples of structures in which the barrier layer is E, the layer obtained from the adhesive resin is Ad, the layer obtained from the thermoplastic resin is T, and direct lamination is represented by " / " include structures such as T / E / T, E / Ad / T, T / Ad / E / Ad / T, E / Ad / T / Ad / E, and E / Ad / T / Ad / E / Ad / T / Ad / E / Ad / E / Ad / E. Each of these layers may be a single layer or a multilayer. The layer Ad obtained from the adhesive resin may be included in the thermoplastic resin layer formed from the thermoplastic resin.

[0052] Examples of the thermoplastic resin include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene, and other olefin homopolymers or copolymers; polyesters such as polyethylene terephthalate; polyester elastomers; polyamides such as nylon-6 and nylon-66; polystyrene; polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyurethane elastomers, polycarbonate, chlorinated polyethylene, chlorinated polypropylene, etc. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.

[0053] The adhesive resin is not particularly limited as long as it has adhesiveness to the gas barrier layer and layers composed of other components, but an adhesive resin containing a carboxylic acid-modified polyolefin is preferred. The carboxylic acid-modified polyolefin is preferably a modified olefin polymer containing a carboxyl group in which an ethylenically unsaturated carboxylic acid, its ester, or its anhydride is chemically bonded to an olefin polymer. Here, the olefin polymer means polyolefins such as polyethylene, linear low-density polyethylene, polypropylene, and polybutene, and copolymers of olefins and other monomers. Among them, linear low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer are preferred, and linear low-density polyethylene and ethylene-vinyl acetate copolymer are particularly preferred.

[0054] From the viewpoint of improving the puncture strength, the multilayer structure of the present invention is preferably provided with a barrier layer on the outermost layer. When the multilayer structure of the present invention is provided with a barrier layer on the outermost layer, it is preferable to produce the multilayer structure of the present invention by coextrusion molding, and then, an inorganic vapor deposition layer may be formed on the barrier layer of the multilayer structure, or a layer made of another component may be laminated. Since EVOH has a high affinity with inorganic vapor deposition layers, particularly vapor deposition layers of aluminum or aluminum oxide, the interlayer adhesion between the barrier layer and the inorganic vapor deposition layer tends to be good. Examples of layer configurations having a barrier layer on the outermost layer include E for the barrier layer, Ad for the layer obtained from an adhesive resin, T for the layer obtained from a thermoplastic resin, and E / Ad / T, E / Ad / T / Ad / E, E / Ad / T / Ad / E / Ad / T / Ad / E, etc., when the layers are directly laminated with " / ". In addition, when the multilayer structure has a barrier layer on the outermost layer, T is preferably a polyolefin from the viewpoint of improving recyclability. In addition, even if the resin composition of the present invention has a barrier layer as the outermost layer, it may tend to have excellent melt moldability, and in particular, it may be possible to suppress the generation of eye plugs during extrusion. In addition, in a multilayer structure having a barrier layer as the outermost layer, it may be preferable to stretch at least uniaxially. By adopting such an embodiment, it is possible to reduce the thickness of the barrier layer E while improving the mechanical properties and gas barrier properties, and therefore it is possible to obtain a gas barrier packaging material with good recyclability. In some cases, it is preferable to stretch uniaxially in the machine direction (MD direction), and in other cases, it is preferable to stretch biaxially. Specifically, it is preferable that the layer structure of E / Ad / T is stretched, and in this case, it is preferable that T is polyethylene or polypropylene, and Ad is a polyethylene-based resin or a polypropylene-based resin. In addition, an embodiment in which an inorganic vapor deposition layer is provided on the exposed surface side of the barrier layer E is also suitable, and the inorganic vapor deposition layer is preferably either a metal vapor deposition layer containing aluminum as a main component or an inorganic oxide vapor deposition layer containing alumina or silica as a main component. A metal vapor deposition layer is preferred when light-blocking properties are to be imparted, but an inorganic oxide vapor deposition layer is preferred from the standpoints of visibility of the contents as a packaging material, microwave suitability, and the ability to suppress the generation of gels and lumps when the ground material is melt-molded.In a layer structure such as inorganic vapor deposition layer / E / Ad / T, when E / Ad / T is stretched, it may be preferable to further provide a heat seal layer such as unstretched polyethylene or unstretched polypropylene on the inner layer side, and it may be preferable to further laminate a stretched polyethylene layer or a stretched polypropylene layer on the outer layer side in order to increase the mechanical strength of the film.

[0055] The method for producing the multilayer structure of the present invention is not particularly limited, and examples thereof include a method of melt-extruding other components onto a molded article (film, sheet, etc.) made of the resin composition of the present invention, a method of co-extruding the resin composition of the present invention and other components, a method of coinjection molding the resin composition of the present invention and other components, and a method of laminating a barrier layer made of the resin composition of the present invention and a layer made of other components using a known adhesive such as an organic titanium compound, an isocyanate compound, or a polyester-based compound.

[0056] The method for co-extrusion of the resin composition of the present invention and other components is not particularly limited, and examples thereof include a multi-manifold merging type T-die method, a feed block merging type T-die method, and an inflation method.

[0057] The multilayer structure of the present invention may be in the form of a film or sheet, and may be molded into various shapes. The multilayer structure of the present invention can be used for packaging materials, containers, tubes, etc., and can also be suitably used as a material for thermoforming, such as thermoformed containers. The thermoformed product obtained from the multilayer structure of the present invention has few defects such as streaks and is excellent in appearance. Such a thermoformed product is also one embodiment of the multilayer structure of the present invention. EXAMPLES

[0058] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0059] [Materials used] <Fluoropolymer (B)> B-1: Vinylidene fluoride-hexafluoropropylene copolymer (MFR at 230°C and 10.9 kg load: 38 g / 10 min, melting point: 124°C) B-2: Vinylidene fluoride-hexafluoropropylene copolymer (MFR at 230°C and 10.9 kg load: 19 g / 10 min, melting point: 142°C) B-3: Vinylidene fluoride-hexafluoropropylene copolymer (MFR at 230°C and 10.9 kg load: 11 g / 10 min, melting point: 165°C)

[0060] [Evaluation method] (1) Ethylene unit content and degree of saponification The crude EVOH obtained in the synthesis example was dried in a vacuum dryer at 120°C for 12 hours. The vacuum-dried EVOH was dissolved in deuterated dimethylsulfoxide containing tetramethylsilane as an internal standard substance and trifluoroacetic acid as an additive, and the solution was analyzed by a 500 MHz spectrometer. 1 Measurement was performed at 80° C. using H-NMR ("GX-500" manufactured by JEOL Ltd.), and the ethylene unit content and degree of saponification were determined from the peak intensity ratio of ethylene units, vinyl alcohol units, and vinyl ester units.

[0061] (2) Determination of sodium ions, phosphate and boron compounds 0.5 g of the dried EVOH pellets obtained in each Example and Comparative Example were placed in a Teflon (registered trademark) pressure vessel, and 5 mL of concentrated nitric acid was added thereto and decomposed at room temperature for 30 minutes. After 30 minutes, the vessel was covered and heated at 150°C for 10 minutes and then at 180°C for 5 minutes using a wet decomposition device (MWS-2, manufactured by Actac Co., Ltd.) to decompose the pellets, and then cooled to room temperature. This treatment liquid was transferred to a 50 mL measuring flask (manufactured by TPX (registered trademark)) and made up to 10 mL with pure water. The metal content of the obtained solution was analyzed using an ICP emission spectrometer (OPTIMA4300DV, manufactured by PerkinElmer Co., Ltd.), and the amount of sodium ions (sodium elements), the amount of phosphoric acid converted into phosphate roots, and the content of boron compounds converted into boron atoms were calculated. In addition, a calibration curve prepared using a commercially available standard solution was used for this quantification.

[0062] (3) Determination of acetic acid 20 g of the EVOH pellets obtained in each Example and Comparative Example were added to 100 ml of ion-exchanged water and extracted by heating at 95°C for 6 hours. The extract was neutralized with 1 / 50 N NaOH using phenolphthalein as an indicator to quantify the acetic acid content. The acetic acid content was calculated taking into account the phosphoric acid content.

[0063] (4) Melt flow rate (MFR) The MFR of the EVOH pellets obtained in each of the Examples and Comparative Examples was measured at 210°C under a load of 2,160 g in accordance with JIS K 7210-1 (2014) using a Melt Indexer L244 (manufactured by Takara Kogyo Co., Ltd.).

[0064] (5) Quantitative determination of aldehydes 0.50 g of the resin composition pellets obtained in each Example and Comparative Example were frozen and crushed to obtain a sample, and 50.0 mg of the sample was weighed into a glass tube for a thermal desorption gas chromatograph mass spectrometer to prepare a sample tube. Using the thermal desorption gas chromatograph mass spectrometer described below, the sample was heated under the following conditions to adsorb the entire amount of volatile gas from the sample into the adsorption tube once, and then the gas re-emitted from the adsorption tube was separated in a column to detect the peaks of each component. A calibration curve was created from the peak areas of standard samples of crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal, and each was quantified by the absolute calibration curve method. When measuring the standard sample, the standard sample was impregnated into an adsorption tube (manufactured by Tenax (registered trademark) / Carboxen (registered trademark)), and the adsorption tube impregnated with the standard sample was used instead of the sample tube. The temperature at the time of release after sample adsorption was changed from the sample tube temperature of 150°C to the adsorption tube temperature of 260°C, but the measurement was performed in the same manner as in the measurement of the sample tube. (Heating desorption section) Device: TurboMatrix-ATD (PerkinElmer Japan) Temperature when adsorbing the sample to the adsorption tube: 150℃ (sample tube), -30℃ (adsorption tube), 250℃ (valve), 260℃ (transfer line) Adsorption time in the adsorption tube: 10 minutes Temperature at the time of release after sample adsorption: 170°C (sample tube), 260°C (adsorption tube), 250°C (valve), 260°C (transfer line) Adsorption tube discharge time: 35 minutes Carrier gas: Helium Carrier gas flow rate to column: 1.0 ml / min Pressure: 120kPa (Gas chromatograph mass spectrometry section) Equipment: 7890B GC System, 5977B MSD (Agilent Technologies) Column: DB-WAX UI (length: 30 m, inner diameter: 0.25 mm, film thickness: 0.50 μm) Column oven temperature: 40°C for 5 minutes, then heat up to 240°C at a rate of 10°C / min and hold for 10 minutes (total measurement temperature: 35 minutes) Transfer line (connection) temperature: 240℃ Ionization conditions: EI+ Detected ion mass range: m / z=29-600 Detection method: SCAN (Standard sample) 2,4-Hexadienal: Aldrich 2,4,6-Octatrienal: Produced by NARD Laboratories

[0065] (6)Piercing strength In accordance with JIS Z 1707, the monolayer film having a thickness of 100 μm obtained in each Example and Comparative Example was conditioned under the conditions of 23 ° C. / 50% RH, then cut into a circle having a diameter of 10 cm, the test piece was fixed using a jig, and a semicircular needle having a diameter of 1.0 mm and a tip shape radius of 0.5 mm was pierced at a speed of 50 mm / min using AUTOGRAPH AGS-H (manufactured by Shimadzu Corporation), and the maximum puncture strength until the needle penetrated was measured. Using the obtained puncture strength (T2) and the puncture strength (T1) of Comparative Example 1 not containing the fluorine-based polymer (B), the increase rate of the puncture strength was calculated from the formula ((T2-T1) / T1) × 100 (%). If the increase rate of the maximum puncture strength was 10% or more, it was judged to have good puncture strength.

[0066] (7) Coloring of the film before light irradiation test The monolayer films having a thickness of 100 μm obtained in each of the Examples and Comparative Examples were visually evaluated, and the degree of coloration was evaluated according to the following criteria: If the evaluation was A to C, it was determined that coloration was suppressed. (standard) A: There was almost no coloring. B: Slightly discolored. C: It was colored. D: Significantly discolored.

[0067] (8) Coloration of the film after light irradiation test The 100 μm thick monolayer films obtained in each Example and Comparative Example were stored for 30 days while being irradiated with light in a light irradiation tester "LTD-2010" (manufactured by Tokyo Rikakikai Co., Ltd.) under conditions of 40°C, 50% RH, and illuminance of 20,000 lux. The degree of coloration of the film after the light irradiation test was compared with the degree of coloration before light irradiation and evaluated according to the following criteria. If the evaluation was A to C, it was determined that coloration was suppressed. (standard) A: The degree of coloration was almost the same as before exposure to light. B: Slightly more colored than before exposure to light. C: More colored than before exposure to light. D: Significantly more pigmented than before exposure to light.

[0068] (9) Haze value For the single layer films having a thickness of 100 μm obtained in each of the Examples and Comparative Examples, the haze value was measured using a reflectance / transmittance meter "HR-100" (manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with ASTM D1003-61.

[0069] (10) Oxygen permeability Using the resin composition pellets obtained in each Example and Comparative Example, a single layer film was produced under the following conditions using a 20 mm single screw extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 3.5, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. Note that only in Examples 9 and 10, the temperature from C2 to the die was set to 220°C. Setting temperature: C1 / C2 / C3 / die = 180 / 200 / 200 / 200℃ Screw rotation speed: 40 rpm Discharge amount: 1.2kg / hour Take-off roll temperature: 80℃ Take-off roll speed: 3.0 m / min Film thickness: 20μm The obtained monolayer film with a thickness of 20 μm was measured using an oxygen permeability measuring device "OX-TRAN2 / 20" manufactured by MOCON (detection limit: 0.01 cc 20 μm / (m 2 The measurements were performed in accordance with the method described in JIS K 7126 (isobaric method) under conditions of a temperature of 30°C and a humidity of 65% RH using a 1000-mPa (1.0-day.atm) pressure sensor.

[0070] (Synthesis Example 1) A 200L pressurized reactor equipped with a jacket, a stirrer, a nitrogen inlet, an ethylene inlet, and an initiator addition inlet was charged with 80.0 kg of vinyl acetate (hereinafter sometimes referred to as VAc) and 9.6 kg of methanol (hereinafter sometimes referred to as MeOH), and nitrogen bubbling was performed for 30 minutes to replace the atmosphere in the reactor with nitrogen. Next, the temperature in the reactor was adjusted to 60°C, and ethylene was introduced so that the pressure (ethylene pressure) of the reactor was 6.12 MPa, and 29.6 g of 2,2'-azobis(2,4-dimethylvaleronitrile) ("V-65" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as an initiator to start polymerization. During polymerization, the ethylene pressure was maintained at 6.12 MPa, and the polymerization temperature was maintained at 60°C. After 5 hours, it was confirmed that the conversion rate of VAc (polymerization rate based on VAc) had reached 54.7%, and the system was cooled. A MeOH solution in which 37.5 g of sorbic acid was dissolved in 25 kg of methanol was added to terminate the polymerization. The reaction vessel was opened to release ethylene, and nitrogen gas was bubbled through to completely remove ethylene. The polymerization liquid was then removed from the reaction vessel and diluted with 20 L of MeOH. This diluted liquid was fed from the top of a tower-type vessel, and MeOH vapor was fed from the bottom of the vessel to remove unreacted monomers remaining in the polymerization liquid together with the MeOH vapor, and a MeOH solution of ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as EVAc) was obtained.

[0071] Next, 100 kg of MeOH solution containing 20% ​​by mass 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. The solution was heated to 60°C while nitrogen gas was blown into it, and a MeOH solution with a sodium hydroxide concentration of 2N was added at a rate of 300 mL / min for 2 hours. After the addition of the MeOH solution containing sodium hydroxide was completed, the temperature in the system was kept at 60°C, and the saponification reaction was allowed to proceed for 2 hours while stirring and discharging MeOH and methyl acetate produced by the saponification reaction out of the reaction tank. Then, 5.8 kg of acetic acid was added to stop the saponification reaction.

[0072] Then, 75 L of ion-exchanged water was added while heating and stirring at 80°C, MeOH was discharged outside the reaction tank, and EVOH was precipitated. The precipitated EVOH was collected by decantation and pulverized in a grinder. The obtained EVOH powder was put into a 1 g / L aqueous acetic acid solution (bath ratio 20; equivalent to a ratio of 20 L of aqueous solution per 1 kg of powder) and stirred and washed for 2 hours. It was deliquified, and further put into a 1 g / L aqueous acetic acid solution (bath ratio 20) and stirred and washed for 2 hours. It was deliquified again, put into ion-exchanged water (bath ratio 20), stirred and washed for 2 hours, and deliquified. This operation was repeated three times for purification. Next, it was stirred and immersed in 250 L of an aqueous solution containing 0.5 g / L of acetic acid and 0.1 g / L of sodium acetate for 4 hours, deliquified, and dried at 60°C for 16 hours to obtain 10.2 kg of crude dried EVOH. The above operation was repeated to obtain 10.3 kg of crude EVOH, resulting in a total of 20.5 kg of crude EVOH (A1). The ethylene unit content and saponification degree of the obtained crude EVOH (A1) were measured according to the method described in the above evaluation method (1). The results are shown in Table 2.

[0073] (Synthesis Examples 2 and 3) A crude dried product of EVOH (A2) (Synthesis Example 2) and a crude dried product of EVOH (A3) (Synthesis Example 3) were prepared and evaluated in the same manner as in Synthesis Example 1, except that the polymerization conditions and saponification conditions of EVOH were changed as shown in Table 1. The results are shown in Table 2.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Example 1] In a 60 L stirring tank equipped with a jacket, a stirrer and a reflux condenser, 2 kg of the crude dried EVOH (A1) obtained in Synthesis Example 1, 0.8 kg of water and 2.2 kg of MeOH were charged and stirred at 60°C for 5 hours to completely dissolve. 2,4-hexadienal was added to the obtained solution. This solution was extruded through a 4 mm diameter gold plate into a mixture of water / MeOH = 90 / 10 cooled to -5°C to precipitate in the form of strands, and the strands were cut into pellets with a strand cutter to obtain hydrous pellets of EVOH. The moisture content of the obtained hydrous pellets of EVOH was measured with a Mettler halogen moisture meter "HR73" and found to be 52% by mass.

[0077] The obtained EVOH hydrous pellets were placed in a 1g / L aqueous acetic acid solution (bath ratio 20) and washed with stirring for 2 hours. The pellets were deliquinated and then placed in a 1g / L aqueous acetic acid solution (bath ratio 20) and washed with stirring for 2 hours. After deliquification, the aqueous acetic acid solution was renewed and the same procedure was carried out. The pellets were washed with the aqueous acetic acid solution, deliquinated, placed in ion-exchanged water (bath ratio 20), washed with stirring for 2 hours, and then deliquinated three times. The procedure was repeated until the electrical conductivity of the washing solution was 3μS / cm or less (measured with Toa Denpa Kogyo Co., Ltd.'s "CM-30ET"), and EVOH hydrous pellets from which the catalyst residue from the saponification reaction had been removed were obtained.

[0078] The obtained hydrous pellets were put into an aqueous solution (bath ratio 20) containing sodium acetate, acetic acid, phosphoric acid and boric acid, and immersed for 4 hours while stirring periodically for chemical treatment. The pellets were dehydrated and dried under a nitrogen stream with an oxygen concentration of 1% by volume or less at 80°C for 3 hours and at 105°C for 16 hours to obtain cylindrical (average diameter 2.8 mm, average height 3.2 mm) dried EVOH pellets containing EVOH (A1), sodium ions (sodium salt), acetic acid, phosphoric acid, boric acid and 2,4-hexadienal. The obtained dried EVOH pellets were quantitatively evaluated for sodium ions, phosphoric acid and boric acid, acetic acid, MFR and aldehyde according to the methods described in the above evaluation methods (2) to (5). The results are shown in Tables 2 and 3. The contents of each component other than EVOH are all based on the content of EVOH. The amount of each component added was adjusted so that the contents of sodium ions (sodium salts), acetic acid, phosphoric acid, and 2,4-hexadienal were as shown in Tables 2 and 3.

[0079] 100 parts by mass of the obtained dried EVOH pellets were dry-blended with 300 ppm of fluorine-based polymer (B-1), and the mixture was melt-kneaded under the following conditions using a 25 mm extruder "2D30W2" manufactured by Toyo Seiki Seisakusho Co., Ltd., and then pelletized to obtain resin composition pellets. Set temperature C1 / C2 / C3 / C4 / C5 / die=160 / 200 / 200 / 200 / 200 / 200℃ Screw rotation speed: 100 rpm Discharge amount: 6.0kg / hour

[0080] Using the obtained resin composition pellets, a monolayer film was formed under the following conditions using a 20 mm single screw extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 3.5, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. The obtained monolayer film was evaluated for puncture strength, coloration of the film before and after the light irradiation test, and haze value using the methods described in the above evaluation methods (6) to (9). The results are shown in Table 3. Setting temperature: C1 / C2 / C3 / die = 180 / 200 / 200 / 200℃ Screw rotation speed: 100 rpm Discharge amount: 3.0kg / hour Take-off roll temperature: 80℃ Take-off roll speed: 1.5m / min Film thickness: 100μm

[0081] [Examples 2 to 8, 12 to 15, Comparative Examples 1 to 5] Resin composition pellets and a single layer film were prepared and evaluated in the same manner as in Example 1, except that the type and content of the fluoropolymer (B) and the type and content of the aldehyde (C) were changed as shown in Table 3. The results are shown in Table 3.

[0082] [Examples 9 and 10] Resin composition pellets and monolayer films were produced and evaluated in the same manner as in Example 1, except that the type of EVOH (A) and the type and content of aldehyde (C) were changed as shown in Table 3, and the extrusion temperatures during the production of resin composition pellets and during the formation of monolayer films were changed as shown below. The results are shown in Table 3. Preparation of resin composition pellets Set temperature C1 / C2 / C3 / C4 / C5 / die = 180 / 220 / 220 / 220 / 220 / 220℃ Single layer film preparation Setting temperature: C1 / C2 / C3 / die = 180 / 220 / 220 / 220℃

[0083] [Example 11] 300 ppm of fluorine-based compound (B-1) was dry-blended with 99.99 parts by mass of the dry EVOH pellets obtained in Example 3. Similarly, 63 ppm of tungsten trioxide (manufactured by Fujifilm Wako Pharmaceutical Co., Ltd.) was dry-blended with 0.01 parts by mass of the dry EVOH pellets obtained in Example 3. Resin composition pellets and a single layer film were produced and evaluated in the same manner as in Example 3, except that the obtained dry blend was further dry-blended and used to produce resin composition pellets. The results are shown in Table 3.

[0084] In Examples 3 and 11, a single-layer film having a thickness of 100 μm was continuously produced for 6 hours, and the state of dirt on the take-up roll after film production was evaluated. Compared to Example 3, Example 11 had less adhesion of dirt to the take-up roll.

[0085] [Example 16] Except for not adding boric acid to the aqueous solution into which the hydrous pellets were added, EVOH (A4), resin composition pellets, and a single layer film were produced and evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0086] [Example 17]

[0087] 100 parts by mass of the dried EVOH pellets obtained in Example 3 were dry-blended with 3000 ppm of fluorine-based polymer (B-1), and the mixture was melt-kneaded under the following conditions using a 25 mm extruder "2D30W2" manufactured by Toyo Seiki Seisakusho Co., Ltd., and then pelletized to obtain master batch pellets. Set temperature C1 / C2 / C3 / C4 / C5 / die=160 / 200 / 200 / 200 / 200 / 200℃ Screw rotation speed: 100 rpm Discharge amount: 6.0kg / hour

[0088] Furthermore, 90 parts by mass of the dried EVOH pellets obtained in Example 3 and 10 parts by mass of the master batch pellets were dry blended, and then a single layer film was formed and evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0089] [Table 3]

[0090] From Comparative Example 5, it is seen that when the fluoropolymer (B) is not included, the puncture strength is insufficient, but discoloration after light irradiation is suppressed. On the other hand, in Comparative Example 3, which contains the fluoropolymer (B), discoloration after light irradiation is significantly worse. It is seen that in Example 3, which contains the fluoropolymer (B) and the aldehyde (C) in a specific range, discoloration after light irradiation is suppressed. This is an extremely excellent effect, as it has been found that the aldehyde (C) can solve the problem that arises only when the EVOH (A) and the fluoropolymer (B) are combined.

Claims

1. The composition comprises an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less, a fluorine-containing polymer (B), and an aldehyde (C), the aldehyde (C) is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb); The content of the fluorine-based polymer (B) is 10 ppm or more and 50,000 ppm or less, A resin composition having an aldehyde (C) content of 0.005 ppm or more and 13 ppm or less.

2. The resin composition according to claim 1, wherein the content of 2,4-hexadienal (Ca) is 0.005 ppm or more and 10.0 ppm or less, and the content of 2,4,6-octatrienal (Cb) is 0.005 ppm or more and 5.00 ppm or less.

3. The resin composition according to claim 1, wherein (Ca + Et / 100) / Cb≦2.0, where Et is the ethylene unit content of the ethylene-vinyl alcohol copolymer (A), Ca (ppm) is the 2,4-hexadienal (Ca) content, and Cb (ppm) is the 2,4,6-octatrienal (Cb) content.

4. The resin composition according to claim 1, wherein Et / 100+Ca+Cb≦6.50, where Et is the ethylene unit content of the ethylene-vinyl alcohol copolymer (A), Ca (ppm) is the 2,4-hexadienal (Ca) content, and Cb (ppm) is the 2,4,6-octatrienal (Cb) content.

5. The resin composition according to claim 1, which contains a boron compound in an amount of 50 ppm to 400 ppm in terms of elemental boron.

6. The resin composition according to claim 1, comprising a metal element (D) of Group 6 of the periodic table in an amount of 0.005 ppb or more and 50 ppb or less.

7. The resin composition according to claim 1, wherein the melting point of the fluorine-containing polymer (B) is 100 to 200°C.

8. The resin composition according to claim 1, wherein the melt flow rate of the fluorine-based polymer (B) measured in accordance with JIS K 7210-1 (2014) at 230 ° C. under a load of 10.9 kg is 2.0 to 50 g / 10 min.

9. A molded article comprising the resin composition according to any one of claims 1 to 8.

10. A multilayer structure having at least one layer made of the resin composition according to any one of claims 1 to 8.

11. A multilayer structure having a layer made of the resin composition according to any one of claims 1 to 8 as an outermost layer.

12. The composition comprises an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less, a fluorine-containing polymer (B), and an aldehyde (C), the aldehyde (C) is at least one selected from the group consisting of 2,4-hexadienal (Ca) and 2,4,6-octatrienal (Cb); the content of the fluorine-based polymer (B) is 10,000 ppm or more and 200,000 ppm or less, A masterbatch having an aldehyde (C) content of 0.05 ppm or more and 130 ppm or less.

13. A method for producing the resin composition according to any one of claims 1 to 8, comprising a step of dry-blending and melt-kneading pellets containing an ethylene-vinyl alcohol copolymer (A) and an aldehyde (C) with pellets containing a fluorine-based polymer (B).

14. A method for producing the resin composition according to any one of claims 1 to 8, comprising a step of dry-blending and melt-kneading the masterbatch according to claim 12 with pellets containing an ethylene-vinyl alcohol copolymer (A).