Resin compositions, molded articles, laminates, pipes, hot water circulation pipes, insulated multilayer pipes, and fuel pipes

Abstract

To provide a resin composition comprising an ethylene-vinyl alcohol copolymer (EVOH), having reduced occurrence of neck-in and die build-up during melt-molding and capable of giving a molding which can be used at high temperatures for a long time.SOLUTION: A resin composition comprises an EVOH (A), crotonaldehyde (B1) and an antioxidant (G), and further comprises at least one selected from the group consisting of 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3), with the content g of the antioxidant (G) being 0.01 mass% or more and 5 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to resin compositions, molded articles, laminates, pipes, hot water circulation pipes, insulated multilayer pipes, and fuel pipes. [Background technology]

[0002] Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH") is a polymer material with excellent gas barrier properties such as oxygen, oil resistance, antistatic properties, mechanical strength, and melt moldability. For this reason, EVOH resin compositions are widely used as molding materials for containers, sheets, films, etc. Furthermore, EVOH resin compositions containing antioxidants are molded and used for hot water circulation pipes for floor heating and district heating systems, fuel pipes, etc. Melt molding is generally used for molding containers, pipes, etc. Therefore, resin compositions used for melt molding need to have excellent long-run performance, such as not developing defects like fisheyes or streaks even after prolonged melt molding.

[0003] However, because EVOH has relatively active hydroxyl groups within its molecule, oxidation and crosslinking reactions can proceed in a high-temperature molten state even inside an extrusion molding machine where there is almost no oxygen, potentially generating thermally degraded products. In particular, during long-term continuous operation, these thermally degraded products can accumulate inside the molding machine, generating gel-like particles that cause fish eyes, which can result in EVOH resin compositions having insufficient long-run performance.

[0004] In contrast, Patent Document 1 describes a resin composition containing EVOH and 0.01 to 100 ppm of unsaturated aldehydes that suppresses the occurrence of defects such as fish eyes, gels, and streaks, and exhibits excellent long-run performance.

[0005] Furthermore, in light of the recent trend towards resource and energy conservation, district heating and cooling systems are being widely adopted. District heating and cooling systems supply hot water, chilled water, etc., to multiple buildings from a centralized heating, cooling, and hot water supply facility via laid pipelines. Multilayer insulated pipes, consisting of an inner pipe for transporting gas or liquid, an insulating foam layer covering the inner pipe, and an outer pipe covering the insulating foam layer, are used as pipes in district heating and cooling systems. Insulating foam layers use carbon dioxide, pentane, cyclopentane, etc., as insulating foaming agents. If pipes without oxygen barrier properties are used in the pipeline, oxygen will permeate through the pipes and dissolve into the circulating water, potentially leading to corrosion of the metal parts within the system piping. Therefore, to maintain the system over the long term, multilayer pipes with an EVOH layer are widely used. However, the oxidative degradation of EVOH due to oxygen in the air during long-term use remains a problem. This oxidative degradation reduces mechanical strength, and when cracks parallel to the length of the EVOH layer are formed, foaming gas diffuses from the pipe, not only reducing thermal insulation performance but also accelerating corrosion of the metal parts of the system. To solve these problems, there is a need to further extend the lifespan of the EVOH layer. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2013 / 146961 [Overview of the project] [Problems that the invention aims to solve]

[0007] When using the EVOH resin composition of the above Patent Document 1, in film forming by a T-die, it has been found that neck-in may occur, where the width of the film extruded from the effective width of the die is smaller, which can be a problem. As a result of the inventors' intensive studies, surprisingly, it has been found that an EVOH resin composition containing a specific plurality of types of unsaturated aldehydes in a specific ratio can suppress such neck-in. However, when attempting to suppress neck-in and adjusting the content of a plurality of types of unsaturated aldehydes, it has been found that depending on the ratio of the above plurality of types of unsaturated aldehydes, a new problem occurs in that die build-up (meaning deposits on the outer surface of the die lip) easily adheres to the outer surface of the discharge port (die lip) of the molten resin composition.

[0008] On the other hand, there is a case where a laminate pipe or the like is manufactured by co-extruding with an EVOH layer as the outermost layer. The occurrence of the above die build-up causes drawbacks when the EVOH layer is co-extruded as the outermost layer of the laminate, where the range where the EVOH contacts the die lip is large, and it can become a significant problem when used at a high temperature for a long period.

[0009] The present invention has been made based on such circumstances, and its object is to provide a resin composition containing EVOH, in which neck-in and die build-up during melt molding are suppressed, and a molded body or the like that can be used at a high temperature for a long period, as well as a molded body, laminate, pipe, hot water circulation pipe, heat-insulating multilayer pipe, and fuel pipe using the same.

Means for Solving the Problems

[0010] The above object is [1] A resin composition comprising an ethylene-vinyl alcohol copolymer (A) (hereinafter sometimes abbreviated as "EVOH (A)") having an ethylene unit content of 20 mol% or more and 60 mol% or less, crotonaldehyde (B1), and an antioxidant (G), further comprising at least one selected from the group consisting of 2,4-hexadienal (B2) and 2,4,6-octatrieneal (B3), satisfying the following formulas (1) and (2), and having a content g of the antioxidant (G) of 0.01% by mass or more and 5% by mass or less; 2.0 ≦ b1 / (b2 + b3) < 150.0 ···(1) b2 + 2b3 ≦ 0.65 ···(2) In the above formulas (1) and (2), b1 is the content (ppm) of crotonaldehyde (B1) with respect to EVOH (A), b2 is the content (ppm) of 2,4-hexadienal (B2) with respect to EVOH (A), and b3 is the content (ppm) of 2,4,6-octatrieneal (B3) with respect to EVOH (A). [2] The resin composition according to [1], wherein the total content (b1 + b2 + b3) of crotonaldehyde (B1), 2,4-hexadienal (B2), and 2,4,6-octatrieneal (B3) with respect to EVOH (A) is 0.01 ppm or more and 7.0 ppm or less; [3] The resin composition according to [1] or [2], wherein the content b1 of crotonaldehyde (B1) is 0.01 ppm or more and 4.0 ppm or less; [4] The resin composition according to any one of [1] to [3], wherein the content b2 of 2,4-hexadienal (B2) is 0.005 ppm or more and 0.65 ppm or less; [5] The resin composition according to any one of [1] to [4], wherein the content b3 of 2,4,6-octatrieneal (B3) is 0.325 ppm or less; [6] The resin composition according to any one of [1] to [5], further comprising a conjugated polyene compound (C), and having a content c of the conjugated polyene compound (C) with respect to EVOH (A) of 1 ppm or more and less than 300 ppm; [7] The resin composition according to [6], wherein the conjugated polyene compound (C) is sorbic acid; [8] A resin composition according to any of [1] to [7], further containing a thermoplastic elastomer (F), wherein the mass ratio of the thermoplastic elastomer (F) to EVOH (A) (F / A) is 5 / 95 or more and 35 / 65 or less; [9] The resin composition of [8] wherein the thermoplastic elastomer (F) is at least one selected from the group consisting of polyester-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, and polyolefin-based thermoplastic elastomers; A molded article having a portion made of any of the resin compositions

[10] [1] to [9]; A laminate having at least one layer made of any of the resin compositions

[11] [1] to [9]; A pipe having a layer made of any of the resin compositions

[12] [1] to [9];

[13]

[12] pipes for hot water circulation;

[14] Insulated multilayer pipes consisting of the pipes of

[12] further having an insulating foam layer; Fuel pipe consisting of pipes

[15]

[12] ; This is achieved by providing [the necessary services / services]. [Effects of the Invention]

[0011] According to the present invention, a resin composition containing EVOH is available that suppresses neck-in and die build-up during melt molding, and can produce molded articles that can be used at high temperatures for extended periods. The present invention also provides molded articles, laminates, pipes, hot water circulation pipes, insulated multilayer pipes, and fuel pipes using the same. [Modes for carrying out the invention]

[0012] <Resin composition> The resin composition of the present invention comprises EVOH (A), crotonaldehyde (B1), and an antioxidant (G), further comprising at least one selected from the group consisting of 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3), satisfying the following formulas (1) and (2), and the content of antioxidant (G) in g is 0.01% by mass or more and 5% by mass or less. 2.0≦b1 / (b2+b3)<150.0 (1) b² + 2b³ ≤ 0.65 ···(2) In formulas (1) and (2) above, b1 is the content of crotonaldehyde (B1) relative to EVOH (A) (ppm), b2 is the content of 2,4-hexadienal (B2) relative to EVOH (A) (ppm), and b3 is the content of 2,4,6-octatrienal (B3) relative to EVOH (A) (ppm). In this specification, the content expressed in ppm is the content on a mass basis.

[0013] A value of b1 / (b2+b3) between 2.0 and less than 150.0 tends to result in good neck-in resistance. On the other hand, 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3) affect die buildup, and 2,4,6-octatrienal (B3) in particular has a significant effect on die buildup. Therefore, a value of b2+2b3 of 0.65 ppm or less tends to suppress die buildup. For this reason, the resin composition of the present invention can be suitably used as a melt molding material. Furthermore, since the resin composition contains a predetermined amount of antioxidant (G), molded articles that can be used at high temperatures for a long period of time can be obtained from this resin composition. In this specification, crotonaldehyde (B1), 2,4-hexadienal (B2), and 2,4,6-octatrienal (B3) may be collectively referred to as unsaturated aliphatic aldehyde (B).

[0014] (EVOH(A)) EVOH(A) is a copolymer having ethylene units and vinyl alcohol units, with an ethylene unit content of 20 mol% to 60 mol%. EVOH(A) is usually obtained by saponification of an ethylene-vinyl ester copolymer. The production and saponification of ethylene-vinyl ester copolymers can be carried out by known methods. Examples of vinyl esters include vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate, vinyl versaticate, and other aliphatic carboxylic acid vinyl esters, with vinyl acetate being preferred.

[0015] The ethylene unit content of EVOH(A) is 20 mol% or more, preferably 25 mol% or more, and more preferably 27 mol% or more. The ethylene unit content of EVOH(A) is 60 mol% or less, preferably 55 mol% or less, and more preferably 50 mol% or less. If the ethylene unit content is less than 20 mol%, the thermal stability during melt extrusion decreases, gelation becomes more likely, and streaks, fish eyes, and other defects tend to occur. The occurrence of streaks, fish eyes, and other defects becomes particularly noticeable when operating at higher temperatures or speeds for longer periods than under general conditions. If the ethylene unit content exceeds 60 mol%, the gas barrier properties tend to decrease.

[0016] The degree of saponification of EVOH(A) is preferably 90 mol% or higher, more preferably 95 mol% or higher, and even more preferably 99 mol% or higher. When the degree of saponification of EVOH(A) is 90 mol% or higher, the gas barrier properties, thermal stability, moisture resistance, etc., of the resin composition of the present invention and the various molded articles obtained from the resin composition of the present invention tend to be good. Furthermore, the degree of saponification may be 100 mol% or less, 99.97 mol% or less, or 99.94 mol% or less.

[0017] Furthermore, EVOH(A) may have other structural units other than ethylene units, vinyl alcohol units, and vinyl ester units, to the extent that the objectives of the present invention are not hindered. When EVOH(A) has the above-mentioned other structural units, the content of these other structural units relative to the total structural units of EVOH(A) 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. Also, when EVOH(A) has the above-mentioned other structural units, their content may be 0.05 mol% or more, or 0.10 mol% or more. Other structural units mentioned above include, for example, unsaturated carboxylic 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; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, or their salts; vinylsilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, and γ-methacryloxypropylmethoxysilane; and structural units derived from alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, etc.

[0018] The above-mentioned other structural units may be at least one of the following: structural unit (I) represented by formula (I), structural unit (II) represented by formula (II), and structural unit (III) represented by formula (III).

[0019] [ka]

[0020] In equations (I), (II), and (III), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R9 , R 10 and R 11 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, or a hydroxyl group. Also, R 1 , R 2 and R 3 among a pair of, R 4 and R 5 , R 6 and R 7 may combine to form part of a ring structure. Some or all of the hydrogen atoms of the above aliphatic hydrocarbon group having 1 to 10 carbon atoms, alicyclic hydrocarbon group having 3 to 10 carbon atoms, and aromatic hydrocarbon group having 6 to 10 carbon atoms may be substituted with a hydroxyl group, an alkoxy group, a carboxyl group, or a halogen atom. In formula (III), R 12 and R 13 each independently represents a hydrogen atom, a formyl group, or an alkanoyl group having 2 to 10 carbon atoms.

[0021] When EVOH (A) has the above structural unit (I), (II), or (III), the flexibility and processing characteristics of the resin composition are improved, and the stretchability and thermoformability, etc. in various molded articles obtained tend to be good.

[0022] In the above structural unit (I), (II), or (III), examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include an alkyl group, an alkenyl group, etc., examples of the alicyclic hydrocarbon group having 3 to 10 carbon atoms include a cycloalkyl group, a cycloalkenyl group, etc., and examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenyl group, etc.

[0023] In the above structural unit (I), the above R 1 , R 2 and R 3Preferably, each of these is independently a hydrogen atom, a methyl group, an ethyl group, a hydroxyl group, a hydroxymethyl group, or a hydroxyethyl group. Among these, it is more preferable that each of these be independently a hydrogen atom, a methyl group, a hydroxyl group, or a hydroxymethyl group, from the viewpoint of further improving the moldability of the resin composition and the stretchability and thermoformability of the various molded articles obtained.

[0024] The method for incorporating the above structural unit (I) into EVOH(A) is not particularly limited, and examples include copolymerizing monomers induced to structural unit (I) in the polymerization of ethylene and vinyl ester. Monomers derived to structural unit (I) include alkenes such as propylene, butylene, pentene, and hexene; 3-hydroxy-1-propene, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, 3,4-diasiloxy-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-diasiloxy-2-methyl-1-butene, 4-hydroxy-1-pentene, 5-hydroxy-1-pentene, 4 Examples of alkenes having a hydroxyl group or ester group include 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-acyloxy-1-hexene, and 5,6-diasiloxy-1-hexene. In particular, propylene, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, and 3,4-diasiloxy-1-butene are preferred from the viewpoint of copolymerization reactivity and the processability and gas barrier properties of the resulting molded articles. "Asiloxy" is preferably acetoxy, specifically 3-acetoxy-1-propene, 3-acetoxy-1-butene, 4-acetoxy-1-butene, and 3,4-diacetoxy-1-butene. In the case of alkenes containing esters, they are converted to the above structural unit (I) during the saponification reaction.

[0025] In the above structural unit (II), R 4 and R 5It is preferable that both are hydrogen atoms. In particular, R 4 and R 5 Both are hydrogen atoms, and the above R 6 and R 7 It is more preferable that one of them is an aliphatic hydrocarbon group having 1 to 10 carbon atoms and the other is a hydrogen atom. The aliphatic hydrocarbon group is preferably an alkyl group or an alkenyl group. From the viewpoint of particularly emphasizing the gas barrier properties of the resulting molded articles, R 6 and R 7 It is more preferable that one of them is a methyl group or an ethyl group and the other is a hydrogen atom. Also, the above R 6 and R 7 One of them is (CH2) h It is even more preferable that the substituent is represented by OH (where h is an integer from 1 to 8), and the other atom is a hydrogen atom. (CH2) h In substituents represented by OH, h is preferably an integer from 1 to 4, more preferably 1 or 2, and even more preferably 1.

[0026] The method for incorporating the above structural unit (II) into EVOH(A) is not particularly limited. For example, a method of incorporating it by reacting EVOH(A) obtained by a saponification reaction with a monovalent epoxy compound can be used. As the monovalent epoxy compound, compounds represented by the following formulas (IV) to (X) are preferably used.

[0027] [ka]

[0028] In the above equations (IV) to (X), R 14 , R 15 , R 16 , R 17 and R 18Each of these independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms (alkyl groups, alkenyl groups, etc.), an alicyclic hydrocarbon group having 3 to 10 carbon atoms (cycloalkyl groups, cycloalkenyl groups, etc.), or an aliphatic hydrocarbon group having 6 to 10 carbon atoms (phenyl groups, etc.). Also, i, j, k, p, and q each independently represent an integer from 1 to 8. However, R 17 If R is a hydrogen atom, 18 It is a group other than a hydrogen atom.

[0029] Examples of monovalent epoxy compounds represented by formula (IV) above 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, etc. Examples of monovalent epoxy compounds represented by formula (V) above include various alkylglycidyl ethers, etc. Examples of monovalent epoxy compounds represented by formula (VI) include various alkylene glycol monoglycidyl ethers. Examples of monovalent epoxy compounds represented by formula (VII) include various alkenyl glycidyl ethers. Examples of monovalent epoxy compounds represented by formula (VIII) include various epoxy alkanols such as glycidol. Examples of monovalent epoxy compounds represented by formula (IX) include various epoxycycloalkanes. Examples of monovalent epoxy compounds represented by formula (X) include various epoxycycloalkenes.

[0030] Among the monovalent epoxy compounds mentioned above, epoxy compounds having 2 to 8 carbon atoms are preferred. Particularly from the viewpoint of ease of handling and reactivity, monovalent epoxy compounds having 2 to 6 carbon atoms are more preferred, and 2 to 4 carbon atoms are even more preferred. Furthermore, it is especially preferred that the monovalent epoxy compound is a compound represented by formula (IV) or formula (V) above. Specifically, from the viewpoint of reactivity with EVOH(A), processability of the resin composition and the various molded articles obtained, and gas barrier properties, 1,2-epoxybutane, 2,3-epoxybutane, epoxypropane, epoxyethane, or glycidol are preferred, with epoxypropane or glycidol being more preferred among them.

[0031] In the above structural unit (III), R 8 , R 9 , R 10 and R 11 The aliphatic hydrocarbon group is preferably a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms, and such aliphatic hydrocarbon group is preferably a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, or n-pentyl group.

[0032] The method for incorporating the above structural unit (III) into EVOH(A) is not particularly limited, and for example, the method described in Japanese Patent Application Publication No. 2014-034647 can be cited.

[0033] The lower limit of the melting point of EVOH(A) is preferably 140°C, more preferably 150°C, and even more preferably 160°C. On the other hand, the upper limit of the melting point is preferably 220°C, more preferably 210°C, and even more preferably 200°C. When the melting point of EVOH(A) is within the above range, melt moldability is improved, and neck-in and die build-up during melt molding tend to be further suppressed. The melting point of EVOH(A) can be the value measured by the method described in the examples.

[0034] EVOH(A) may be used alone or in combination of two or more types.

[0035] The lower limit of the EVOH(A) content in the resin composition of the present invention may be 50% by mass, but is preferably 70% by mass, more preferably 80% by mass, particularly preferably 90% by mass, and may also be 95% by mass, 99% by mass, or 99.9% by mass, from the viewpoint of gas barrier properties, etc. The resin constituting the resin composition of the present invention may be substantially composed of EVOH(A) alone. On the other hand, the upper limit of the EVOH(A) content in the resin composition of the present invention may be, for example, 99.9% by mass, and may also be 99% by mass, 95% by mass, or 90% by mass. Note that the EVOH(A) content refers to the content (percentage) in the resin composition in a dry state. The same applies hereafter to the content based on the resin composition.

[0036] (Unsaturated aliphatic aldehyde (B)) The resin composition of the present invention comprises crotonaldehyde (B1) and further comprises at least one selected from the group consisting of 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3).

[0037] The lower limit of the content b1 of crotonaldehyde (B1) relative to EVOH (A) in the resin composition of the present invention is preferably 0.01 ppm, more preferably 0.20 ppm, even more preferably 0.40 ppm, and may be even more preferably 0.70 ppm or 1.20 ppm. On the other hand, the upper limit of the content b1 is preferably 4.0 ppm, more preferably 3.5 ppm, even more preferably 2.7 ppm, and may be even more preferably 2.0 ppm or 1.5 ppm. When the content b1 is within the above range, it becomes easier to adjust the values ​​of b1 / (b2+b3), b1+b2+b3, and b2+2b3, which will be described later, to a suitable range. In addition, when the content b1 is within the above range, discoloration tends to be suppressed.

[0038] In one embodiment, the resin composition of the present invention contains 2,4-hexadienal (B2) in a specific ratio to crotonaldehyde (B1), which tends to suppress dye buildup while exhibiting excellent neck-in resistance. The lower limit of the content b2 of 2,4-hexadienal (B2) relative to EVOH (A) in the resin composition of the present invention is preferably 0.005 ppm, more preferably 0.01 ppm, and even more preferably 0.02 ppm. On the other hand, the upper limit of the content b2 is preferably 0.65 ppm, more preferably 0.20 ppm, even more preferably 0.10 ppm, even more preferably 0.08 ppm, and particularly preferably 0.06 ppm. When the content b2 is within the above range, it becomes easier to adjust the values ​​of b1 / (b2+b3), b1+b2+b3, and b2+2b3, which will be described later, to a suitable range. In addition, when the content b2 is within the above range, discoloration tends to be suppressed.

[0039] In one embodiment, the resin composition of the present invention tends to have excellent neck-in resistance while suppressing die buildup by containing 2,4,6-octatrienal (B3) in a specific ratio to crotonaldehyde (B1). Compared to 2,4-hexadienal (B2), 2,4-octatrienal (B3) has a greater effect on die buildup with respect to the amount added. Therefore, from the viewpoint of suppressing die buildup and improving neck-in resistance, the resin composition of the present invention preferably contains 2,4-hexadienal (B2) rather than 2,4,6-octatrienal (B3). The upper limit of the content b3 of 2,4,6-octatrienal (B3) relative to EVOH (A) in the resin composition of the present invention is preferably 0.325 ppm, more preferably 0.23 ppm, even more preferably 0.07 ppm, and particularly preferably 0.04 ppm. The lower limit of the content B3 may be 0 ppm or 0.005 ppm. When the content b3 is within the above range, it becomes easier to adjust the values ​​of b1 / (b2+b3), b1+b2+b3, and b2+2b3, which will be described later, to a suitable range. In addition, when the content b3 is within the above range, discoloration tends to be suppressed.

[0040] In the resin composition of the present invention, the ratio of the total content of 2,4-hexadienal (B2) b2 (ppm) and 2,4,6-octatrienal (B3) b3 (ppm) to the content of crotonaldehyde (B1) b1 (ppm) (b1 / (b2+b3)) is 2.0 or more and less than 150.0, resulting in excellent neck-in resistance. This neck-in resistance is an effect not seen when any of the unsaturated aliphatic aldehyde (B) compounds are used alone, and is only achieved when b1 / (b2+b3) falls within a specific range. The lower limit of b1 / (b2+b3) is preferably 4.0, more preferably 8.0. On the other hand, the upper limit of b1 / (b2+b3) is preferably 60.0, more preferably 25.0, and even more preferably 13.0. By keeping b1 / (b2+b3) within the above range, neck-in can be suppressed more effectively.

[0041] In the resin composition of the present invention, the upper limit of the sum of the content of 2,4-hexadienal (B2) b2 (ppm) and twice the content of 2,4,6-octatrienal (B3) b3 (ppm) (b2 + 2b3) is 0.65 ppm or less, preferably 0.50 ppm, more preferably 0.30 ppm, and even more preferably 0.10 ppm. If b2 + 2b3 exceeds the above upper limit, the occurrence of die buildup cannot be suppressed. b2 + 2b3 may be 0.005 ppm or more, or 0.01 ppm or more.

[0042] In the resin composition of the present invention, the upper limit of the total content (b1+b2+b3) of crotonaldehyde (B1), 2,4-hexadienal (B2), and 2,4,6-octatrienal (B3) relative to EVOH (A) is preferably 7.0 ppm, more preferably 4.0 ppm, even more preferably 3.5 ppm, even more preferably 3.0 ppm, even more preferably 1.5 ppm, and in some cases particularly preferably 1.0 ppm. By keeping b1+b2+b3 below the above upper limit, the discoloration of the resin composition can be sufficiently suppressed. On the other hand, the lower limit of b1+b2+b3 is preferably 0.01 ppm, more preferably 0.10 ppm, and in some cases even more preferably 0.30 ppm or 0.50 ppm.

[0043] (Antioxidant (G)) The resin composition of the present invention further contains an antioxidant (G) to improve the oxidation resistance and degradation properties of the resulting molded articles. When the resin composition further contains an antioxidant, it is possible to suppress the occurrence of cracks when molded articles such as pipes formed from the resin composition are used at high temperatures for a long period of time.

[0044] Antioxidant (G) is a compound that has antioxidant properties. The melting point of antioxidant (G) is not necessarily limited, but it is preferably 170°C or lower. When the melting point of antioxidant (G) is 170°C or lower, it melts easily in the extruder when manufacturing the resin composition by melt mixing. Therefore, it is possible to suppress the localization of antioxidant (G) in the resin composition and the discoloration of high-concentration areas. Furthermore, the melting point of antioxidant (G) is preferably 50°C or higher, and in some cases, 100°C or higher is more preferable. When the melting point of antioxidant (G) is 50°C or higher, it is possible to suppress the bleed-out of the antioxidant onto the surface of the resulting molded article (pipe, etc.), which would result in a poor appearance.

[0045] The molecular weight of the antioxidant (G) is preferably 300 or more. When the molecular weight of the antioxidant (G) is 300 or more, it is possible to suppress the bleeding out of the antioxidant onto the surface and the resulting poor appearance of the molded article when a molded article is obtained from the resin composition of the present invention, and the thermal stability of the resin composition is also improved. The molecular weight is more preferably 400 or more, and particularly preferably 500 or more. On the other hand, there is no particular upper limit to the molecular weight of the antioxidant (G), but from the viewpoint of dispersibility, it is preferably 8000 or less, more preferably 6000 or less, even more preferably 4000 or less, and particularly preferably 2000 or less.

[0046] Compounds having a hindered phenol group are preferably used as the antioxidant (G). Compounds having a hindered phenol group have excellent thermal stability themselves, and also have the ability to capture oxygen radicals, which are the cause of oxidative degradation. When incorporated into a resin composition as an antioxidant, they have an excellent effect in preventing oxidative degradation.

[0047] As compounds having a hindered phenol group, commercially available products can be used, for example, the following products. (1) BASF's "IRGANOX 1010": Melting point 110-125°C, molecular weight 1178, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (2) BASF's "IRGANOX 1076": Melting point 50-55°C, molecular weight 531, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (3) BASF's "IRGANOX 1098": Melting point 156-161°C, molecular weight 637, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (4) BASF's "IRGANOX 245": Melting point 76-79°C, molecular weight 587, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] (5) BASF's "IRGANOX 259": Melting point 104-108°C, molecular weight 639, 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (6) Sumilizer MDP-s manufactured by Sumitomo Chemical Co., Ltd.: Melting point approximately 128°C, molecular weight 341, 2,2'-methylene-bis(4-methyl-6-tert-butylphenol) (7) Sumilizer GM, manufactured by Sumitomo Chemical Co., Ltd.: Melting point approximately 128°C, molecular weight 395, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate (8) Sumilizer GA-80 manufactured by Sumitomo Chemical Co., Ltd.: Melting point approximately 110°C, molecular weight 741, 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane

[0048] Compounds having a hindered amine group are also suitably used as antioxidants (G). When compounds having a hindered amine group are incorporated into the resin composition as antioxidants (G), they not only prevent the thermal degradation of EVOH(A), but also have the effect of capturing aldehydes produced by the thermal decomposition of EVOH(A), thereby reducing the generation of decomposition gases and suppressing the generation of voids or bubbles during molding. Furthermore, by capturing aldehydes, the problem of aldehyde odors impairing the taste of the contents when the resin composition of the present invention is used as a food packaging container is also improved.

[0049] Preferred compounds having a hindered amine group are piperidine derivatives, and particularly preferred are 2,2,6,6-tetraalkylpiperidine derivatives having a substituent at the 4-position. Examples of substituents at the 4-position include carboxyl groups, alkoxy groups, and alkylamino groups.

[0050] Furthermore, while an alkyl group may be substituted at the N position of the hindered amine group, it is preferable to use one to which a hydrogen atom is bonded, as this provides superior thermal stability.

[0051] As compounds having a hindered amine group, commercially available products can be used, and examples include the following products. (9) BASF "TINUVIN 770": Melting point 81-85°C, molecular weight 481, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (10) BASF's "TINUVIN 765": Liquid compound, molecular weight 509, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (mixture) (11) BASF "TINUVIN 622LD": Melting point 55-70°C, molecular weight 3100-4000, dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (12) BASF "CHIMASSORB 119FL": Melting point 130-140℃, molecular weight 2000 or more, N,N'-bis(3-aminopropyl)ethylenediamine·2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate (13) BASF "CHIMASSORB 944LD": Melting point 100-135℃, Molecular weight 2000-3100, Poly[[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl](2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene(2,2,6,6-tetramethyl-4-pipezyl)imino]] (14) BASF "TINUVIN 144": Melting point 146-150℃, molecular weight 685, bis(1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate (15) BASF UVINUL 4050H: Melting point 157°C, molecular weight 450, N,N'-1,6-hexanediylbis{N-(2,2,6,6-tetramethyl-4-piperidinyl)-formamide} (16) BASF UVINUL 5050H: Melting point 104-112°C, molecular weight approximately 3500, compound having the following structural formula.

[0052] [ka]

[0053] These compounds having a hindered phenol group or a hindered amine group may be used alone or in combination of two or more.

[0054] The lower limit of the antioxidant (G) content in the resin composition of the present invention is 0.01% by mass, preferably 0.1% by mass, and more preferably 0.3% by mass. The upper limit of the antioxidant (G) content in g is 5% by mass, preferably 3% by mass, and more preferably 1% by mass. When the antioxidant (G) content in g is within the above range, the antioxidant (G) is well dispersed, and when a molded article or the like is obtained from the resin composition of the present invention, it tends to have an excellent appearance and exhibit good resistance to oxidation degradation, heat resistance, etc.

[0055] (Conjugated polyene compound (C)) The resin composition of the present invention preferably further contains a conjugated polyene compound (C). The conjugated polyene compound (C) can suppress the deterioration of color tone due to oxidative degradation of EVOH (A) during melt molding. Here, the conjugated polyene compound (C) is a compound having a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately linked, and the number of carbon-carbon double bonds is two or more, in other words, a compound having a conjugated double bond. However, 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3) are not considered to be conjugated polyene compounds (C). The conjugated polyene compound (C) 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. Furthermore, there may be multiple sets of conjugated double bond structures in one molecule. For example, compounds that have three conjugated triene structures in the same molecule, such as tung oil, are also included in the conjugated polyene compound (C). A preferred upper limit for the number of conjugated double bonds in the conjugated polyene compound (C) is seven. If the resin composition contains a conjugated polyene compound (C) having eight or more conjugated double bonds, the likelihood of discoloration of the pellets and, consequently, the molded article increases.

[0056] In addition to the conjugated double bond, the conjugated polyene compound (C) may have other functional groups such as carboxyl groups and their salts, hydroxyl groups, ester groups, ether groups, amino groups, imino groups, amide groups, cyano groups, diazo groups, nitro groups, sulfone groups and their salts, sulfonyl groups, sulfoxide groups, sulfide groups, thiol groups, phosphate groups and their salts, phenyl groups, halogen atoms, double bonds, triple bonds, etc.

[0057] The lower limit of the number of carbon atoms in the conjugated polyene compound (C) is preferably 4. The upper limit of the number of carbon atoms in the conjugated polyene compound (C) is preferably 30, and more preferably 10.

[0058] Examples of conjugated polyene compounds (C) include isoprene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-t-butyl-1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 3,4-dimethyl-1,3-pentadiene, and 3-ethyl-1,3-pentadie. 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 Examples include conjugated diene compounds such as ene, 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, sorbate esters, and sorbates; conjugated triene compounds such as 1,3,5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, cholecalciferol, flubene, and tropone; and cyclooctatetraene, 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid.

[0059] The conjugated polyene compound (C) is preferably sorbic acid, sorbate ester, sorbate salt, myrcene, or a mixture of two or more of these, and more preferably sorbic acid, sorbate salt (sodium sorbate, potassium sorbate, etc.), or a mixture thereof. Sorbic acid, sorbate salt, or a mixture thereof is preferred from the viewpoint of hygiene and availability because it has a high effect in suppressing oxidative degradation at high temperatures and is also widely used industrially as a food additive.

[0060] The molecular weight of the conjugated polyene compound (C) 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 (C) is below the above upper limit, the dispersion state of the conjugated polyene compound (C) in the resin composition becomes good, and the appearance after melt molding tends to improve. The lower limit of the molecular weight of the conjugated polyene compound (C) is, for example, 54, but it may also be 60 or 80.

[0061] The lower limit of the content c of the conjugated polyene compound (C) relative to EVOH(A) in the resin composition of the present invention is preferably 1 ppm, more preferably 3 ppm. Furthermore, the content c of the conjugated polyene compound (C) relative to EVOH(A) in the resin composition of the present invention is preferably less than 300 ppm, more preferably 100 ppm or less, even more preferably 70 ppm or less, even more preferably 30 ppm or less, and particularly preferably 20 ppm or less, or 10 ppm or less. When the content c of the conjugated polyene compound (C) is within the above range, the deterioration of hue during melt molding tends to be further suppressed.

[0062] (Thermoplastic elastomer (F)) The resin composition of the present invention may further contain a thermoplastic elastomer (F) in order to improve the flexibility and other properties of molded articles and the like obtained from the resin composition.

[0063] The thermoplastic elastomer (F) is not particularly limited, and polyester-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, etc., can be used. These may be used individually or in combination of two or more. In particular, from the viewpoint of improving flexibility, it is preferable that the thermoplastic elastomer (F) is at least one selected from the group consisting of polystyrene-based thermoplastic elastomers and polyolefin-based thermoplastic elastomers.

[0064] The thermoplastic elastomer (F) is preferably a modified thermoplastic elastomer. The modified thermoplastic elastomer is preferably modified with an unsaturated carboxylic acid or its derivative. Examples of unsaturated carboxylic acids or their derivatives include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate, diethyl maleate, and monomethyl fumarate. Among these, a maleic anhydride-modified thermoplastic elastomer is more preferable. A modified thermoplastic elastomer (F) is preferable because it improves compatibility with EVOH(A), resulting in enhanced gas barrier properties, transparency, flexibility, and peelability.

[0065] Examples of the above-mentioned polyester-based thermoplastic elastomers (hereinafter sometimes referred to as TPEEs) include multiblock copolymers having polyester as the hard segment in the molecule and a polyether or polyester with a low glass transition temperature (Tg) as the soft segment. TPEEs can be classified into the following types based on differences in molecular structure, with polyester-polyether type TPEEs and polyester-polyester type TPEEs being preferred. (1) Polyester / Polyether type TPEE Generally, it is a thermoplastic elastomer using aromatic crystalline polyester as the hard segment and polyether as the soft segment. (2) Polyester Polyester type TPEE This thermoplastic elastomer uses aromatic crystalline polyester as the hard segment and aliphatic polyester as the soft segment. (3) Liquid crystalline TPEE This thermoplastic elastomer uses rigid liquid crystal molecules as the hard segment and aliphatic polyester as the soft segment.

[0066] Examples of the polyester segment include a polyester segment comprising a dicarboxylic acid component such as aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as succinic acid and adipic acid, and a diol component such as aliphatic diols such as ethylene glycol, 1,2-propylene glycol, and 1,4-butanediol; and alicyclic diols such as cyclohexane-1,4-dimethanol. Examples of the polyether segment include aliphatic polyether segments such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. The polyester-based thermoplastic elastomer is preferably a modified polyester-based thermoplastic elastomer, and more preferably a maleic anhydride-modified polyester-based thermoplastic elastomer.

[0067] The polystyrene-based thermoplastic elastomer described above is not particularly limited, but typically comprises a styrene monomer polymer block (Hb) as a hard segment and a conjugated diene compound polymer block or its hydrogenated block (Sb) as a soft segment. The structure of this styrene-based thermoplastic elastomer may be a diblock structure represented by Hb-Sb, a triblock structure represented by Hb-Sb-Hb or Sb-Hb-Sb, a tetrablock structure represented by Hb-Sb-Hb-Sb, or a polyblock structure in which a total of five or more Hb and Sb molecules are linked in a linear chain.

[0068] The styrene monomer used in the above-mentioned styrene monomer polymer block (Hb) is not particularly limited, and examples include styrene and its derivatives. Specifically, examples include styrenes such as styrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, and t-butoxystyrene; vinyl group-containing aromatic compounds such as vinylnaphthalenes such as 1-vinylnaphthalene and 2-vinylnaphthalene; and vinylene group-containing aromatic compounds such as indene and acenaphthylene. Styrene is preferred among these. The styrene monomer may be one type or two or more types.

[0069] The conjugated diene compound used in the above-mentioned conjugated diene compound polymer block or its hydrogenated block (Sb) is not particularly limited, and examples include butadiene, isoprene, 2,3-dimethylbutadiene, pentadiene, hexadiene, etc. Among these, butadiene is preferred. The conjugated diene compound may be just one type or two or more types. Furthermore, other comonomers, such as ethylene, propylene, butylene, and styrene, can also be copolymerized. In addition, the conjugated diene compound polymer block may be a hydrogenated product that is partially or completely hydrogenated.

[0070] Specific examples of polystyrene-based thermoplastic elastomers include styrene-isoprene diblock copolymer (SI), styrene-butadiene diblock copolymer (SB), styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene / isoprene-styrene triblock copolymer (SB / IS), and styrene-butadiene-styrene triblock copolymer (SBS), as well as their hydrogenated derivatives. Among these, at least one selected from the group consisting of hydrogenated styrene-isoprene diblock copolymer (SEP), hydrogenated styrene-butadiene diblock copolymer (SEB), hydrogenated styrene-isoprene-styrene triblock copolymer (SEPS), hydrogenated styrene-butadiene / isoprene-styrene triblock copolymer (SEEPS), and hydrogenated styrene-butadiene-styrene triblock copolymer (SEBS) is preferred. The above polystyrene-based thermoplastic elastomer is preferably a modified polystyrene-based thermoplastic elastomer, and more preferably a maleic anhydride-modified polystyrene-based thermoplastic elastomer.

[0071] The above-mentioned polyolefin-based thermoplastic elastomers include thermoplastic elastomers comprising polyolefin blocks such as polypropylene and polyethylene as hard segments and rubber blocks such as ethylene-propylene-diene copolymer as soft segments. Such thermoplastic elastomers are available in blended and implantable types. Modified polyolefin-based thermoplastic elastomers can also include maleic anhydride-modified ethylene-butene-1 copolymer, maleic anhydride-modified ethylene-propylene copolymer, halogenated butyl rubber, modified polypropylene, and modified polyethylene. The above-mentioned polyolefin-based thermoplastic elastomers are preferably modified polyolefin-based thermoplastic elastomers, and more preferably maleic anhydride-modified polyolefin-based thermoplastic elastomers.

[0072] In the resin composition of the present invention, the lower limit of the mass ratio (F / A) of thermoplastic elastomer (F) to EVOH (A) is preferably 5 / 95, more preferably 8 / 92, even more preferably 12 / 88, and in some cases even more preferably 15 / 85 or 25 / 75. By setting the mass ratio (F / A) to be above the above lower limit, the flexibility resistance and other properties of the resulting molded article can be improved. On the other hand, the upper limit of this mass ratio (F / A) is preferably 35 / 65, more preferably 30 / 70, and in some cases even more preferably 25 / 75. By setting the mass ratio (F / A) to be below the above upper limit, the gas barrier properties and other properties can be further improved.

[0073] (phase separation structure) In the resin composition of the present invention, it is preferable that particles of thermoplastic elastomer (F) are dispersed in a matrix of EVOH (A). That is, it is preferable that the resin composition of the present invention has a sea-island structure in which the sea phase mainly consists of EVOH (A) and the island phase mainly consists of thermoplastic elastomer (F). In this way, by having the sea phase mainly consist of EVOH (A), flexibility is improved while maintaining gas barrier properties.

[0074] When the resin composition of the present invention has a sea-island structure, with the sea phase mainly consisting of EVOH(A) and the island phase mainly consisting of thermoplastic elastomer(F), from the viewpoint of improving transparency, the average particle size of the island phase consisting of thermoplastic elastomer(F) is preferably 4.5 μm or less, more preferably 3.5 μm or less, even more preferably 3.0 μm or less, particularly preferably 2.5 μm or less, and most preferably 2.0 μm or less. The average particle size of thermoplastic elastomer(F) may be 0.1 μm or more. When the average particle size of the island phase consisting of thermoplastic elastomer(F) is within the above range, it is preferable because flexibility is improved and peelability is further improved while maintaining gas barrier properties and transparency. The average particle size of thermoplastic elastomer(F) can be adjusted by adjusting the kneading strength and the composition ratio of EVOH(A) and thermoplastic elastomer(F).

[0075] In the resin composition of the present invention, the refractive index difference between EVOH (A) and thermoplastic elastomer (F) is preferably 0.05 or less, more preferably 0.04 or less, and even more preferably 0.03 or less. The refractive index difference may be 0.005 or more. A refractive index difference within the above range is preferable because it results in better transparency of the resin composition of the present invention.

[0076] (Other optional components) The resin composition of the present invention may contain, as other optional components besides EVOH (A), unsaturated aliphatic aldehyde (B), antioxidant (G), conjugated polyene compound (C), and thermoplastic elastomer (F), boron compounds, carboxylic acids, phosphorus compounds, metal ions, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, heat stabilizers, other resins other than EVOH (A) and thermoplastic elastomer (F), metal salts of higher aliphatic carboxylic acids, etc. The resin composition of the present invention may contain two or more of these components. If the resin composition of the present invention contains other optional components, the upper limit of their total content is preferably 1% by mass, and may also be preferably 0.5% by mass.

[0077] Boron compounds suppress gelation during melt molding and also suppress torque fluctuations (viscosity changes during heating) in extrusion molding machines, etc. Examples of the above boron compounds include boric acids such as orthoboric acid, metaboric acid, and tetraboric acid; boric acid esters such as triethyl borate and trimethyl borate; alkali metal salts or alkaline earth metal salts of the above boric acids, borates such as borax; and boron hydrides. Among these, boric acids are preferred, and orthoboric acid (hereinafter also referred to as "boric acid") is more preferred. The lower limit of the content of the boron compound relative to EVOH(A) is preferably 100 ppm, and more preferably 500 ppm. Furthermore, the upper limit of the content of the boron compound relative to EVOH(A) is preferably 5,000 ppm, more preferably 3,000 ppm, and even more preferably 1,000 ppm. By setting the content of the boron compound to be above the above lower limit, torque fluctuations in extrusion molding machines, etc. can be sufficiently suppressed. On the other hand, by keeping the boron compound content below the above upper limit, gelation during melt molding becomes less likely, improving the appearance of the resin composition and, consequently, the molded product. Note that the boron compound content is expressed as the orthoboric acid equivalent of the boron compound.

[0078] Carboxylic acids prevent discoloration of the resin composition and, consequently, the molded article, and also suppress gelation during melt molding. Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, lactic acid, and their salts. Preferred carboxylic acids are those with four or fewer carbon atoms or saturated carboxylic acids, with acetic acid being more preferred. These acetic acids include acetic acid and acetate salts. It is preferable to use acetic acid and acetate salts in combination, and more preferable to use acetic acid and sodium acetate in combination. The lower limit of the carboxylic acid content relative to EVOH(A) is preferably 50 ppm, more preferably 100 ppm, and even more preferably 150 ppm. The upper limit of the carboxylic acid content relative to EVOH(A) is preferably 1,000 ppm, more preferably 500 ppm, and even more preferably 400 ppm. By setting the carboxylic acid content above the above lower limit, a sufficient discoloration suppression effect can be obtained, and the occurrence of yellowing can be sufficiently suppressed. On the other hand, by keeping the carboxylic acid content below the above upper limit, gelation is less likely to occur during melt molding, especially during long melt molding periods, resulting in a better appearance for molded products.

[0079] Phosphorus compounds suppress the occurrence of defects such as streaks and fish eyes, as well as discoloration, and improve long-run performance. Examples of phosphorus compounds include phosphates such as phosphoric acid and phosphorous acid. The phosphate may be in the form of monophosphate, diphosphate, or tertiary phosphate. The cation species of the phosphate is not particularly limited, but alkali metal salts and alkaline earth metal salts are preferred, of which 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. The lower limit of the phosphorus compound content relative to EVOH(A) is preferably 1 ppm, more preferably 10 ppm, even more preferably 20 ppm, and particularly preferably 30 ppm. The upper limit of the phosphorus compound content relative to EVOH(A) is preferably 200 ppm, more preferably 150 ppm, and even more preferably 100 ppm. By setting the phosphorus compound content above the lower limit or below the upper limit, thermal stability is improved, and the formation of gel-like particles and discoloration during long-term melt molding becomes less likely.

[0080] Examples of metal ions include monovalent metal ions, divalent metal ions, and other transition metal ions, which may consist of one or more types. Among these, monovalent metal ions and divalent metal ions are preferred. Among monovalent metal ions, alkali metal ions are preferred, such as lithium, sodium, potassium, rubidium, and cesium ions, with sodium or potassium ions being preferred from the viewpoint of industrial availability. Examples of alkali metal salts that provide alkali metal ions include aliphatic carboxylates, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, and metal complexes. Among these, aliphatic carboxylates and phosphates are preferred from the viewpoint of availability, and specifically, sodium acetate, potassium acetate, sodium phosphate, and potassium phosphate are preferred. It is also preferable to include divalent metal ions as metal ions. When the metal ions include divalent metal ions, for example, the thermal degradation of EVOH when trim is recovered and reused may be suppressed, and the generation of gel and blemishes in the resulting molded article may be suppressed. Examples of divalent metal ions include beryllium, magnesium, calcium, strontium, barium, and zinc ions, but 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, with carboxylates being preferred. Preferred carboxylic acids constituting the carboxylates are carboxylic acids having 1 to 30 carbon atoms, specifically including acetic acid, propionic acid, butyric acid, stearic acid, lauric acid, montanic acid, behenic acid, octic acid, sebacic acid, ricinoleic acid, myristic acid, palmitic acid, etc., with acetic acid and stearic acid being preferred among them. The lower limit of the metal ion content in EVOH(A) is preferably 1 ppm, more preferably 100 ppm, and even more preferably 150 ppm. On the other hand, the upper limit of the metal ion content is preferably 1,000 ppm, more preferably 400 ppm, and even more preferably 350 ppm. When the metal ion content relative to EVOH(A) is 1 ppm or higher, the resulting laminate tends to have good interlayer adhesion.On the other hand, when the metal ion content is 1,000 ppm or less, the stain resistance tends to be good.

[0081] Examples of plasticizers include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, and phosphate esters. Examples of antistatic agents include pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, and polyethylene glycol (trade name: Carbowax).

[0082] Examples of lubricants include ethylene bisstearamide and butyl stearate. Examples of colorants include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and red iron oxide. Examples of fillers include glass fiber, wollastonite, calcium silicate, talc, and montmorillonite. Examples of heat stabilizers include hindered phenol compounds and hindered amine compounds.

[0083] Other resins besides EVOH(A) and thermoplastic elastomer(F) include, for example, polyamides and polyolefins. Examples of metal salts of higher aliphatic carboxylic acids include, for example, sodium stearate, potassium stearate, calcium stearate, and magnesium stearate.

[0084] In the resin composition of the present invention, the total content of EVOH (A), unsaturated aliphatic aldehyde (B) (crotonaldehyde (B1), 2,4-hexadienal (B2), and 2,4,6-octatrienal (B3)), and antioxidant (G) 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 consist substantially only of EVOH (A), unsaturated aliphatic aldehyde (B), and antioxidant (G), or it may consist only of EVOH (A), unsaturated aliphatic aldehyde (B), and antioxidant (G). In this specification, "substantially consisting only of" means that the inclusion of optional components is permitted as long as it does not affect the effects of the present invention, and in this specification, "consisting only of" means that optional components other than impurities that are inevitably included are excluded.

[0085] The lower limit of the melt flow rate (MFR) of the resin composition of the present invention at 210°C and under a load of 2,160 g is preferably 0.5 g / 10 min, and more preferably 1 g / 10 min. On the other hand, the upper limit of the MFR is preferably 30 g / 10 min, and more preferably 20 g / 10 min. By having the MFR of the resin composition of the present invention within the above range, melt moldability and other properties can be improved. Furthermore, when the MFR of the resin composition of the present invention is within the above range, the neck-in resistance tends to be better.

[0086] <Method for preparing resin compositions> Methods for producing the resin composition of the present invention include a method of producing a resin composition containing EVOH (A) and an unsaturated aliphatic aldehyde (B), and then mixing this resin composition with an antioxidant (G), or a method of mixing EVOH (A), an unsaturated aliphatic aldehyde (B), and an antioxidant (G) all at once. For example, the production method is as follows: (1) A step of copolymerizing ethylene and vinyl ester, and (2) A step of saponifying the copolymer obtained in step (1). A method for producing a resin composition comprising the above, characterized in that the resin composition contains a predetermined amount and a predetermined ratio of an unsaturated aliphatic aldehyde (B) and an antioxidant (G).

[0087] There are no particular limitations on the method for incorporating unsaturated aliphatic aldehyde (B) into the resin composition. Examples include adding unsaturated aliphatic aldehyde (B) in step (1), adding unsaturated aliphatic aldehyde (B) in step (2), or adding unsaturated aliphatic aldehyde (B) to EVOH (A) obtained in step (2). When adopting the method of adding unsaturated aliphatic aldehyde (B) in step (1) or step (2), it is necessary to increase the amount added, taking into account the amount consumed in the polymerization reaction in step (1) and the saponification reaction in step (2), in order to contain the desired amount of unsaturated aliphatic aldehyde (B) in the resulting resin composition. Therefore, when adding unsaturated aliphatic aldehyde (B) in the polymerization or saponification reaction steps, it is preferable to add the amount of unsaturated aliphatic aldehyde (B) that will be consumed. On the other hand, the method of adding an unsaturated aliphatic aldehyde (B) to EVOH (A) obtained from step (2) above is superior in terms of operability because it can be added without considering consumption within the process.

[0088] Methods for adding an unsaturated aliphatic aldehyde (B) to EVOH (A) include, for example, 1) a method of granulating pellets by pre-mixing the unsaturated aliphatic aldehyde (B) with EVOH (A), 2) a method of impregnating strands precipitated in a process of precipitating a paste after saponification of an ethylene-vinyl ester copolymer with the unsaturated aliphatic aldehyde (B), 3) a method of impregnating the precipitated strands with the unsaturated aliphatic aldehyde (B) after cutting them, and 4) a method of re-processing chips of a dried resin composition. Examples of methods include: 5) adding unsaturated aliphatic aldehyde (B) to a dissolved substance; 6) melt-kneading a blend of EVOH (A) and unsaturated aliphatic aldehyde (B); 7) feeding unsaturated aliphatic aldehyde (B) into the EVOH (A) molten material from the middle of an extruder to incorporate it; and 8) creating a masterbatch by granulating a high-concentration blend of unsaturated aliphatic aldehyde (B) with a portion of EVOH (A), dry-blending it with EVOH (A), and melt-kneading it.

[0089] Of these methods, the method of granulating pellets by pre-mixing the unsaturated aliphatic aldehyde (B) with EVOH(A) is preferred from the viewpoint of being able to disperse a trace amount of unsaturated aliphatic aldehyde (B) with high uniformity in EVOH(A). Specifically, a resin composition pellet in which the unsaturated aliphatic aldehyde (B) is mixed with EVOH(A) with high uniformity can be obtained by adding the unsaturated aliphatic aldehyde (B) to a solution obtained by dissolving EVOH(A) in a good solvent such as a water / methanol mixed solvent, extruding the mixed solution into a poor solvent from a nozzle or the like to precipitate and / or solidify it, and then washing and / or drying it.

[0090] A resin composition containing EVOH (A) and an unsaturated aliphatic aldehyde (B) can be mixed with an antioxidant (G) by known methods such as melt kneading. In this case, other components may be added and then melt kneaded. A method for mixing EVOH (A), an unsaturated aliphatic aldehyde (B), and an antioxidant (G) together is to dry blend or add the antioxidant (G) together with the unsaturated aliphatic aldehyde (B) in the methods 4), 5), 6), or 7) for producing the above mixture. In this case, other components may also be dry blended or added. For mixing other components, a ribbon blender, a high-speed mixer kneader, a mixing roll, an extruder, an intensive mixer, etc., can be used.

[0091] The resin composition of the present invention is preferably in pellet form for ease of handling. The shape of the pellets of the resin composition of the present invention is not particularly limited, but examples include cylindrical, prismatic, spherical, and lenticular. Among these, cylindrical, spherical, or lenticular pellets are preferred from the viewpoint of pellet transport stability, handling, and productivity. In the case of cylindrical pellets, the diameter is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and the height is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and even more preferably 3 mm to 5 mm. In the case of spherical or lenticular pellets, the length in the short direction is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and the length in the long direction is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm.

[0092] <Molded body> The resin composition of the present invention can be formed into molded articles such as films, sheets, tubes, bags, and bottles by melt molding or the like. Molded articles having a portion made of the resin composition of the present invention can suppress neck-in and die build-up, thus the molded articles of the present invention have high productivity. The molded articles of the present invention only need to have a portion formed from the resin composition of the present invention. That is, the molded articles of the present invention may be made only from the resin composition of the present invention, or they may be made from a portion made only from the resin composition of the present invention and other portions. In this specification, a film usually refers to something with a thickness of less than 300 μm, and a sheet usually refers to something with a thickness of 300 μm or more. Examples of melt molding methods 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), but is preferably around 150 to 270°C. These molded articles can also be crushed and remolded for reuse. Films, sheets, etc. can also be uniaxially or biaxially stretched.

[0093] (Films and sheets) Films and sheets formed from the resin composition of the present invention (hereinafter sometimes abbreviated as "films, etc.") have high productivity because the occurrence of neck-in and die build-up is suppressed. Such films, etc. include single-layer films, etc. and multi-layer films, etc. Such films, etc. can be used as various packaging materials, etc.

[0094] Films and the like can be manufactured by the same method as described above for manufacturing molded articles. In particular, a method comprising a cast molding step of melt-extruding the resin composition of the present invention onto a casting roll, and a step of stretching the unstretched film obtained from the resin composition of the present invention (uniaxial stretching step, sequential biaxial stretching step, simultaneous biaxial stretching step, inflation molding step, etc.) is preferred. With such a method for manufacturing films and the like, the break resistance can be improved by including these steps.

[0095] <Laminate> The laminate of the present invention has at least one layer made of the resin composition of the present invention (hereinafter also referred to as the "barrier layer" or "EVOH layer"), and further has layers made of other components. The laminate has advantages such as improved functionality compared to a single-layer molded article. Furthermore, since the laminate of the present invention is manufactured using a resin composition that suppresses neck-in and die build-up, it has high continuous productivity. The lower limit of the number of layers in the laminate may be two or three. The upper limit of the number of layers in the laminate may be 1000, 100, or 10. Furthermore, the laminate of the present invention may further have layers formed from components other than resin, such as layers formed from paper, metal layers, etc.

[0096] As for the layers made of other components, a thermoplastic resin layer formed from a thermoplastic resin is preferred. The layer structure of the laminate of the present invention is not particularly limited, and when the barrier layer is represented by E, the layer obtained from the adhesive resin by Ad, the layer obtained from the thermoplastic resin by T, and direct lamination is represented by " / ", examples of structures include T / E / T, E / Ad / T, T / Ad / E / Ad / T, E / Ad / T / Ad / E, E / Ad / T / Ad / E / Ad / T / Ad / E, etc. Each of these layers may be a single layer or a multilayer. Note that the layer Ad obtained from the adhesive resin may also be included in the thermoplastic resin layer formed from a thermoplastic resin.

[0097] Examples of thermoplastic resins 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 with 4 to 20 carbon atoms) copolymer, polybutene, polypentene, and other olefins alone or copolymers thereof; 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, and chlorinated polypropylene. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferred.

[0098] The adhesive resin is not particularly limited as long as it has adhesion to the gas barrier layer and the layers made of other components, but an adhesive resin containing a carboxylic acid-modified polyolefin is preferred. As the carboxylic acid-modified polyolefin, a modified olefin polymer containing a carboxyl group obtained by chemically bonding an ethylenically unsaturated carboxylic acid, its ester, or its anhydride to an olefin polymer is preferred. Here, olefin polymer refers to polyolefins such as polyethylene, linear low-density polyethylene, polypropylene, and polybutene, and copolymers of olefins and other monomers. Among these, 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.

[0099] From the viewpoint of suppressing die buildup, the laminate of the present invention is also preferably used in a form in which a barrier layer is provided as the outermost layer. When a barrier layer is provided as the outermost layer, the laminate of the present invention is preferably manufactured by co-extrusion molding, and thereafter an inorganic vapor deposition layer may be formed on the barrier layer of such laminate, or a layer made of other components may be laminated. Since EVOH has a high affinity for inorganic vapor deposition layers, particularly aluminum or aluminum oxide vapor deposition layers, the interlayer adhesion between the barrier layer and the inorganic vapor deposition layer tends to be good. Examples of layer configurations in which a barrier layer is provided as the outermost layer include E / Ad / T, E / Ad / T / Ad / E, E / Ad / T / Ad / E / Ad / T / Ad / E, etc., where E is the barrier layer, Ad is the layer obtained from the adhesive resin, T is the layer obtained from the thermoplastic resin, and " / " indicates direct lamination. When the laminate has a barrier layer as the outermost layer, T is preferably a polyolefin from the viewpoint of improving recyclability.

[0100] The method for producing the laminate of the present invention is not particularly limited, and examples 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 co-injection 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 organotitanium compound, an isocyanate compound, or a polyester compound.

[0101] The method for co-extruding the resin composition of the present invention with other components is not particularly limited and can include the multi-manifold confluence T-die method, the feedblock confluence T-die method, the inflation method, and the like.

[0102] When the laminate of the present invention is a multilayer film or sheet, the average thickness is not particularly limited, and the lower limit may be, for example, 1 μm, 5 μm, or 10 μm. On the other hand, the upper limit of the average thickness may be, for example, 3 mm, 1 mm, 300 μm, or 100 μm. The shape of the laminate is not particularly limited as long as it has a multilayer structure. Multilayer thermoformed containers, multilayer blow-molded containers, multilayer pipes, vapor-deposited films, etc., are also included in the form of the laminate.

[0103] The molded articles, laminates, etc. of the present invention may be in the form of films or sheets, and may be molded into various shapes. The molded articles, laminates, etc. of the present invention can be used as packaging materials, containers, tubes, etc., and can also be suitably used as materials for thermoforming, such as thermoformed containers. Thermoformed articles obtained from the laminates of the present invention have few defects such as streaks and have excellent appearance. Such thermoformed articles are also one embodiment of the molded articles, laminates, etc. of the present invention. Furthermore, in the molded articles, laminates, etc. of the present invention, because an antioxidant is contained in the barrier layer (EVOH layer), cracks due to oxidative degradation are less likely to occur in the barrier layer (EVOH layer) even when used at high temperatures for a long period of time. For this reason, they are suitable for everyday goods, packaging materials, machine parts, etc. used outdoors. Examples of applications in which the above-mentioned features of molded articles, laminates, etc. are particularly effective include packaging materials for food and beverages, packing materials for containers, films, agricultural films, geomembranes, medical infusion bag materials, high-pressure tank materials, gasoline tank materials, fuel containers, tire tube materials, shoe cushioning materials, inner bag materials for bag-in-boxes, tank materials for organic liquid storage, pipes (pipe materials for transporting organic liquids, hot water pipe materials for heating (hot water pipe materials for underfloor heating, etc.), etc.), resin wallpaper, plant culture media, etc. In particular, the molded articles and laminates of the present invention are preferably used as films, pipes, agricultural films, plant culture media, and geomembranes that are used outdoors and are prone to deterioration due to heat and light, in which the EVOH layer is co-extruded as the outermost layer of the laminate.

[0104] <pipe> The pipe of the present invention has a layer made of the resin composition of the present invention. This pipe has fewer defects such as streaks during melt molding, has excellent appearance, and shows improved stability when used at high temperatures for extended periods compared to pipes using the same EVOH.

[0105] Furthermore, in the layer of the pipe made of the resin composition of the present invention, this resin composition contains a predetermined amount of unsaturated aliphatic aldehyde (B) and antioxidant (G). As a result, a molded article with fewer defects is produced, suppressing the occurrence of cracks and enabling long-term use.

[0106] The pipe may be a single-layer pipe or a multi-layer pipe. If the pipe is a multi-layer pipe, the layer structure can be similar to that of the laminate of the present invention described above. For example, if the layer structure of the multi-layer pipe is represented by E as the layer made of the resin composition of the present invention, Ad as the adhesive layer, and T as the layer obtained from another thermoplastic resin, then structures such as T / E / T, E / Ad / T, and T / Ad / E / Ad / T can be used. Each of these layers may be a single layer or a multi-layer pipe. Specific examples of resins used for the adhesive layer and the layer obtained from another thermoplastic resin include those similar to those used for these layers in the laminate of the present invention. Furthermore, the method for manufacturing the pipe is not particularly limited, and various molding methods exemplified as methods for melt-molding the resin composition of the present invention can be employed.

[0107] The use of this pipe is not particularly limited and can be used, for example, as a hot water circulation pipe, a multi-layered insulated pipe, a fuel pipe, a gas pipe, etc.

[0108] When the pipe of the present invention is a multilayer pipe and is used as a hot water circulation pipe, a three-layer configuration of T / Ad / E with the layer made of the above-mentioned resin composition as the outermost layer is generally adopted. This is because existing single-layer pipe manufacturing lines, such as those for cross-linked polyolefins, can be easily converted into multilayer pipe manufacturing lines by adding co-extrusion coating equipment for the resin composition of the present invention and adhesive resin, and many pipe manufacturers actually adopt this configuration.

[0109] Providing polyolefin layers or the like on both sides of a layer made of the resin composition of the present invention, and using the resin composition layer as an intermediate layer, is effective in preventing damage to the resin composition layer. However, when multilayer pipes are used as hot water circulation pipes such as floor heating pipes, they are usually buried under the floor, so the risk of damage to the resin composition layer due to physical impact is relatively small. Therefore, from the viewpoint of gas barrier properties, it is preferable to place the resin composition layer as the outermost layer. Generally, the gas barrier properties of EVOH(A) show a large humidity dependence, and the barrier properties decrease under high humidity conditions. Therefore, by placing the layer made of the resin composition of the present invention as the outermost layer, the layer made of the resin composition of the present invention, which is mainly composed of EVOH(A), is located at the furthest point from the inner surface of the pipe that comes into contact with water, resulting in the most advantageous layer configuration in terms of the barrier performance of the multilayer pipe. On the other hand, when the EVOH layer is generally placed as the outermost layer, it comes into direct contact with air and is therefore susceptible to oxidative degradation. In such environments, by placing a layer made of the resin composition of the present invention, which is less susceptible to oxidative degradation even at high temperatures, as the outermost layer, the effect of providing a multilayer pipe that has good barrier properties while reducing the occurrence of cracks due to oxidative degradation can be more effectively demonstrated.

[0110] Furthermore, when the pipe of the present invention is used in a multilayer insulated pipe for district heating and cooling, it is preferable to have a three-layer configuration of T / Ad / E (hereinafter sometimes abbreviated as laminate 1) in which the layer made of the resin composition of the present invention is placed inside the thermoplastic resin layer, or a five-layer configuration of T / Ad / E / Ad / T (hereinafter sometimes abbreviated as laminate 2) from the viewpoint of preventing damage to the resin composition layer.

[0111] The configuration of the insulated multilayer pipes for district heating and cooling is not particularly limited, but it is preferable that the laminates 1 or 2 described above be arranged in the following order from the inside out: an inner pipe, an insulating foam layer covering the inner pipe, and an outer layer made of the resin composition of the present invention.

[0112] The type (material), shape, and size of the pipe used for the inner tube are not particularly limited as long as they can transport a heat transfer medium such as gas or liquid, and can be appropriately selected according to the type of heat transfer medium, the application and usage of the piping material, etc. Specifically, examples include laminates 1 or 2 having layers made of metals such as steel, stainless steel, and aluminum, polyolefins (polyethylene, cross-linked polyethylene (PEX), polypropylene, poly-1-butene, poly-4-methyl-1-pentene, etc.), and the resin composition of the present invention, and among these, cross-linked polyethylene (PEX) is preferably used.

[0113] The insulating foam that makes up the insulating foam layer can be polyurethane foam, polyethylene foam, polystyrene foam, phenolic foam, or polyisocyanurate foam, and polyurethane foam is preferably used from the viewpoint of improving insulating performance.

[0114] As blowing agents for insulating foams, fluorocarbons, various alternative fluorocarbons, water, chlorinated hydrocarbons, hydrocarbons, carbon dioxide, etc. are used, but from the viewpoint of foaming effect and environmental impact, hydrocarbons, specifically n-pentane or cyclopentane, are preferably used.

[0115] One method for manufacturing a multilayer insulated pipe is to place an inner pipe for transporting a heat transfer medium inside a pipe-shaped outer layer, fix the inner pipe with a spacer to form a double pipe, and then inject various foam concentrates into the gap between the inner pipe and the outer layer, allowing them to foam and solidify. The material of the spacer is not particularly limited, but polyethylene or polyurethane is preferred in order to reduce damage to the inner pipe and outer layer caused by the spacer.

[0116] When the pipe of the present invention is used as a fuel pipe, it is more preferable that the layer made of the resin composition of the present invention further contains a thermoplastic elastomer (F). The inclusion of a thermoplastic elastomer (F) further improves the crack resistance of the pipe.

[0117] When used in fuel pipes, the innermost layer is formed to be conductive. To achieve this, the thermoplastic resin of the innermost layer is mixed with conductive additives that are known in themselves, such as carbon black or graphite fibers.

[0118] <Methods for manufacturing pipes, etc.> The following describes a method for manufacturing a multilayer pipe as an example of a pipe, but some or all of this manufacturing method can also be applied to the manufacturing of other molded articles (films, sheets, etc.). As described above, a multilayer pipe can be manufactured by co-extruding a resin composition of the present invention and an adhesive resin onto a single-layer pipe such as a cross-linked polyolefin. When co-extruding a resin composition of the present invention and an adhesive resin onto a single-layer pipe, it is possible to simply coat the single-layer pipe with a molten film of the resin composition of the present invention and an adhesive resin. However, the adhesive strength between the single-layer pipe and the coating layer may be insufficient, and the coating layer may peel off during long-term use, resulting in a loss of gas barrier properties. As a countermeasure, it is effective to flame-treat and / or corona-discharge treat the surface of the pipe to be coated before coating.

[0119] Other multilayer molding methods for manufacturing multilayer pipes include co-extrusion, which involves using a number of extruders corresponding to the types of resin layers and simultaneously extruding the molten resin flows within these extruders in a layered state. Other multilayer molding methods, such as dry lamination, may also be employed.

[0120] The manufacturing method for multilayer pipes preferably includes a step of cooling with water at 10-70°C immediately after molding. That is, it is desirable to solidify the resin composition layer by cooling with water at 10-70°C after melt molding, before the layer made of the resin composition of the present invention solidifies. If the cooling water temperature is too low, cracks due to strain are likely to occur in the layer made of the resin composition of the present invention at the bent portion when the multilayer pipe is bent in the subsequent secondary processing step. The details of the cause of the increased likelihood of cracks due to strain are not clear, but it is presumed that residual stress in the molded product is a contributing factor. From this viewpoint, a cooling water temperature of 15°C or higher is more preferable, and 20°C or higher is even more preferable. On the other hand, if the cooling water temperature is too high, cracks due to strain are likely to occur in the layer made of the resin composition of the present invention at the bent portion during secondary processing. The details of the cause of this are not fully understood, but it is presumed that the degree of crystallinity of the layer made of the resin composition of the present invention becomes too high. From this viewpoint, a cooling water temperature of 60°C or lower is more preferable, and 50°C or lower is even more preferable.

[0121] Various molded products can be obtained by secondary processing of the multilayer pipe obtained by the above method. The secondary processing method is not particularly limited, and known secondary processing methods can be used as appropriate. For example, one method is to heat the multilayer pipe to 80 to 160°C, deform it into the desired shape, and then fix it in that state for 1 minute to 2 hours.

[0122] Furthermore, even when the pipe of the present invention is a single-layer pipe, it can be manufactured by the known molding method described above as a method for melt-molding the resin composition of the present invention. [Examples]

[0123] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0124] [Evaluation Method] (1) Measurement of ethylene unit content and degree of saponification The crude dried 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 dimethyl sulfoxide (DMSO-d6) containing tetramethylsilane (TMS) as an internal standard and trifluoroacetic acid (TFA) as an additive, and heated at 500 MHz. 1 The ethylene unit content and degree of saponification were determined from the peak intensity ratios of ethylene units, vinyl alcohol units, and vinyl ester units using 1H-NMR (GX-500, manufactured by JEOL Ltd.) at 80°C.

[0125] (2) Sodium ion content, phosphoric acid content and boric acid content 0.5 g of the dried resin composition pellets obtained in the reference example and reference comparative example were placed in a Teflon® pressure vessel, and 5 mL of concentrated nitric acid was added to decompose it at room temperature for 30 minutes. After 30 minutes, the lid was closed, and the decomposition was carried out by heating at 150°C for 10 minutes, then at 180°C for 5 minutes, using a wet decomposition apparatus (Actac Co., Ltd. "MWS-2"), and then cooled to room temperature. This processed solution was transferred to a 50 mL volumetric flask (TPX®) and diluted with pure water. The metal content of this solution was analyzed using an ICP emission spectrometer (PerkinElmer "OPTIMA4300DV"), and the content of sodium ions (element sodium), phosphoric acid, and boric acid was measured. The phosphoric acid content was calculated as a phosphate root equivalent, and the boric acid content was calculated as an orthoboric acid equivalent. Calibration curves prepared using commercially available standard solutions were used for quantification.

[0126] (3) Acetic acid content 20 g of dried resin composition pellets obtained in the reference example and reference comparative example were placed in 100 mL of deionized water and heated at 95°C for 6 hours for extraction. The extract was neutralized and titrated with 1 / 50 N NaOH using phenolphthalein as an indicator to quantify the acetic acid content.

[0127] (4) Melt Flow Rate (MFR) The dried resin composition pellets obtained in the reference example and reference comparative example were filled into a 9.55 mm inner diameter, 162 mm long cylinder of a melt indexer L244 (manufactured by Takara Kogyo Co., Ltd.), melted at 210°C, and then a uniform load was applied to the molten resin composition using a plunger with a mass of 2,160 g and a diameter of 9.48 mm. The amount of resin composition extruded per unit time (g / 10 min) through a 2.1 mm diameter orifice located in the center of the cylinder was measured and defined as the MFR (Metal Flow Rate).

[0128] (5) Determination of crotonaldehyde, 2,4-hexadienal and 2,4,6-octatrienal Samples were prepared by freeze-pulverizing 0.50 g of dried resin composition pellets obtained in the Reference Example, Reference Comparative Example, Example, and Comparative Example, and weighing 50.0 mg of the resulting sample into a glass tube for a thermal desorption gas chromatograph mass spectrometer. Using the thermal desorption gas chromatograph mass spectrometer described below, the sample was heated under the conditions described below to adsorb the volatile gas from the sample into an adsorption tube. The gas re-released from the adsorption tube was then separated by a column, and the peaks for each component were detected. Calibration curves were created from the peak areas of standard samples of crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal, and each component was quantified using the absolute calibration curve method. When measuring the standard sample, the standard sample was impregnated into an adsorption tube (manufactured by Tenax® / Carboxen®), and the adsorption tube impregnated with the standard sample was used instead of the sample tube. The temperature at which the sample was released after adsorption was changed from the sample tube temperature of 170°C to the adsorption tube temperature of 260°C, but the measurement was performed in the same manner as when measuring the sample tube. (Heating desorption section) Device: TurboMatrix-ATD (manufactured by PerkinElmer Japan) Temperature when adsorbing the sample onto the adsorption tube: 170°C (sample tube), -30°C (adsorption tube), 250°C (valve), 260°C (transfer line) Adsorption time to the adsorption tube: 10 minutes Temperature during release after sample adsorption: 170°C (sample tube), 260°C (adsorption tube), 250°C (valve), 260°C (transfer line) Adsorption tube release time: 35 minutes Carrier gas: Flow rate of carrier gas into helium column: 1.0 ml / min Pressure: 120kPa (Gas Chromatography and Mass Spectrometry Department) Equipment: 7890B GC System, 7977B MSD (manufactured by Agilent Technologies) Column: DB-WAX UI (Length: 30m, Inner diameter: 0.25mm, Film thickness: 0.50μm) Column oven temperature: Hold at 40°C for 5 minutes, then raise the temperature to 240°C at a rate of 10°C / min, and hold for 10 minutes (total measurement time: 35 minutes). Transfer line (connection point) temperature: 240℃ Ionization conditions: EI+ Detection ion mass range: m / z = 29-600 Detection method: SCAN (Standard sample) Crotonaldehyde: Manufactured by Aldrich. 2,4-Hexadienal: Manufactured by Aldrich. 2,4,6-Octatrienal: Manufactured by Nerd Research Institute

[0129] (6) Determination of sorbic acid and myrcene The dried resin composition pellets obtained in the Reference Example, Reference Comparative Example, Example, and Comparative Example were freeze-dried and pulverized. 22 g of the pulverized material was loaded into a Soxhlet extractor and extracted with 100 mL of chloroform for 16 hours. The amounts of sorbic acid and myrcene in the resulting chloroform extract were quantitatively analyzed by high-performance liquid chromatography to determine the content of sorbic acid and myrcene in the resin composition. Calibration curves prepared using sorbic acid and myrcene standards were used for quantification.

[0130] (7) Dybuild-up evaluation The dried resin composition pellets obtained in the Reference Example, Reference Comparative Example, Example, and Comparative Example were extruded from an extruder under the following conditions. After 60 minutes, the die buildup (die lip) around the die was visually inspected and evaluated according to the following criteria. In cases A to D, it was determined that die buildup was suppressed. (Extruder conditions) • Equipment: 20mmφ single-screw extruder (D2020, manufactured by Toyo Seiki Seisakusho Co., Ltd.) L / D:20 • Screw: Full Flight Screen mesh: 50 mesh / 100 mesh / 50 mesh • Die: φ1mm, 1 hole ·Set temperature: C1 / C2 / C3 / D=180℃ / 220℃ / 220℃ / 220℃ ·Discharge amount: 1.44kg / h • Rotation speed: 100 rpm (Evaluation: Judgment Criteria) A (Good): No eye discharge is present. B (Fairly good): There is a very small amount of eye discharge. C (Acceptable): A small amount of eye discharge is present. D (Slightly Poor): Clear eye discharge is present. E (Defective): Large particles of eye discharge are attached all around the die hole.

[0131] (8) Hue evaluation The Yellow Index (YI) values ​​of the dried resin composition pellets obtained in the Reference Example, Reference Comparative Example, Example, and Comparative Example were measured and calculated using a Hunter LAB Scan XE in accordance with JIS K7373:2006. A smaller value indicates suppressed yellowing and superior hue.

[0132] (9) Evaluation of neck-in resistance during film formation Using the dried resin composition pellets obtained in the Reference Example, Reference Comparative Example, Example, and Comparative Example, the resin composition was extruded from a single-screw extruder under the following conditions. Ten minutes after feeding the dried resin composition pellets, the width of the molten resin (melt curtain) discharged from the T-die was measured at a position 100 mm from the lip (T-die discharge port). The width of the molten resin was evaluated according to the following criteria. In cases A to C, it was determined that neck-in was suppressed. (Extruder conditions) • Extruder: L / D=26, 40mmφ single-screw extruder • Screw: Full Flight • Screw rotation speed: 50 rpm Screen mesh: 50 mesh / 100 mesh / 50 mesh • Die shape: T-shaped, lip width 550mm, lip spacing 0.7mm ·Set temperature: C1 / C2 / C3 / D=170℃ / 240℃ / 260℃ / 260℃ (Evaluation: Judgment Criteria) A (Good): More than 85% of the lip width B (Fairly Good): 82.5% to less than 85% of lip width C (Slightly Poor): Lip width is between 80% and 82.5% D (Defective): Less than 80% of the lip width

[0133] (10) Melting point measurement The crudely dried EVOH obtained in the synthesis example was dried in a vacuum dryer at 120°C for 12 hours. The vacuum-dried EVOH was heated from 30°C to 250°C at a rate of 10°C / min using a differential scanning calorimeter "Q2000" manufactured by TA Instruments, cooled at 50°C / min, and then the melting point was determined from the peak temperature measured by the secondary heating.

[0134] (11) Oxidation resistance [Preparation of single-layer film] Each resin composition pellet obtained in the examples and comparative examples was fabricated under the following conditions to obtain a single-layer film with a thickness of 20 μm. • Equipment: 20mmφ single-screw extruder (D2020, manufactured by Toyo Seiki Seisakusho Co., Ltd.) L / D:20 • Screw: Full Flight • Die width: 30cm • Pickup roll temperature: 80℃ • Screw rotation speed: 40 rpm • Rolling speed: 3.0~3.5m / min ·Set temperature: C1 / C2 / C3 / D=180℃ / 210℃ / 210℃ / 210℃

[0135] For each single-layer film obtained above, the change in tensile strength over time was evaluated by measuring multiple samples with varying heat treatment times under the following evaluation conditions. The time at which the elongation at break became 1 / 4 of that of the untreated sample was determined and used as an indicator of oxidation degradation resistance. (Evaluation criteria) After being treated in a hot air dryer set to 140°C for a specified time, the samples were removed. Subsequently, they were immersed in 20°C water for 5 days, the surface water was wiped off, and they were left to stand in a room at 20°C-65%RH for 2 weeks before tensile strength and elongation measurements were performed under the following conditions. (Measurement conditions) Sample width: 15 mm Chuck spacing: 30mm Tensile speed: 50 mm / min Measurement environment: 20°C - 65%RH

[0136] In the above evaluation, when the elongation at break falls below 1 / 4, the deterioration of the gas barrier properties of the EVOH layer due to crack formation caused by oxidative degradation becomes significant. Therefore, the time it takes for the elongation at break to fall to 1 / 4 can be considered as one of the indicators of the lifespan of EVOH due to oxidative degradation at high temperatures. The time it takes for the elongation at break to fall to 1 / 4 shows an Arrhenius-type temperature dependence. To make the time it takes for the elongation at break to fall to 1 / 4 (lifespan) more than 100 years at 80°C, it is necessary to make the time it takes for the elongation at break to fall to 1 / 4 more than 210 hours at 140°C.

[0137] (12) Evaluation of the gas barrier properties of pipes (Manufacturing of multi-layer pipes) 100 parts by mass of high-density polyethylene (Yukalon Hard BX-50, manufactured by Mitsubishi Petrochemical Co., Ltd., density 0.952 g / cc, MFR 0.5 g / 10 min), 2 parts by mass of vinyltrimethoxysilane dissolved in acetone, and 0.2 parts by mass of dicumyl peroxide were mixed. The mixture was extruded into strands at 230°C using a single-screw extruder to obtain modified polyethylene pellets with 1.5% by mass of vinylsilane added. Next, 5 parts by mass of the high-density polyethylene, which was compounded with 2% by mass of dibutylsudraurate, was added to 100 parts by mass of these pellets and placed in the first extruder. The resin composition pellets obtained in the examples or comparative examples were placed in the second extruder. Furthermore, Mitsui Chemicals, Inc.'s "Admer NF408E" was added to the third extruder as an adhesive resin. Using three types of three-layer circular dies, a multi-layer pipe with an outer diameter of 20 mm was extruded and immediately cooled and solidified by passing it through a cooling water bath adjusted to 40°C. The layer structure of the multilayer pipe consisted of a resin composition layer as the outermost layer, with a density of 100 μm / 100 μm / 2000 μm for the resin composition layer / adhesive resin layer / high-density polyethylene layer. The resulting multilayer pipe was cut to 1 m length, heated in a 140°C hot air dryer for 10 minutes, and then bent at a 90° angle near the center, aligned with a 150 mm outer diameter stainless steel pipe, and held in place for 5 minutes to complete the bending process.

[0138] (OTR (Oxygen Transmissibility) Measurement) One end of the fabricated multilayer pipe was sealed using a silicone rubber stopper and adhesive, and the other end was connected to an oxygen permeability measuring device (OX-TRAN-10 / 50A, manufactured by Modern Control Co., Ltd.). The oxygen permeability before heat treatment was measured under conditions of 20°C / 65%RH.

[0139] Next, the multilayer pipes were placed in a hot air dryer at 100°C and subjected to heat treatment for 216 hours. The oxygen permeability after heat treatment was measured using the multilayer pipes after the heat treatment using the method described above.

[0140] (13) Pipe Die Build-Up Evaluation In the gas barrier performance evaluation of the pipe described in (12) above, the die buildup (die smear) around the die (die lip) after 60 minutes during the fabrication of the multilayer pipe was visually inspected and evaluated according to the following criteria. If the result was A to D, it was determined that the die buildup was suppressed. (Evaluation: Judgment Criteria) A (Good): No eye discharge is present. B (Fairly good): There is a very small amount of eye discharge. C (Acceptable): A small amount of eye discharge is present. D (Slightly Poor): Clear eye discharge is present. E (Defective): Large particles of eye discharge are attached all around the die hole.

[0141] <Synthesis Example 1> In a 200L pressurized reactor equipped with a jacket, stirrer, nitrogen inlet, ethylene inlet, and initiator addition port, 75.0 kg of vinyl acetate (hereinafter sometimes referred to as VAc) and 7.2 kg of methanol (hereinafter sometimes referred to as MeOH) were charged, and the reactor was purged with nitrogen by bubbling with nitrogen for 30 minutes. Next, after adjusting the temperature inside the reactor to 65°C, ethylene was introduced so that the reactor pressure (ethylene pressure) reached 4.13 MPa, and 9.4 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "V-65") was added as a polymerization initiator to start polymerization. During polymerization, the ethylene pressure was maintained at 4.13 MPa and the polymerization temperature at 65°C. After 4 hours, when the conversion rate of VAc (polymerization rate based on VAc) reached 49.7%, the reactor was cooled, and a solution of 0.2 g of copper acetate dissolved in 20 kg of methanol was added to the container to stop the polymerization. After opening the reaction vessel and removing the ethylene, nitrogen gas was bubbled through to completely remove the ethylene. Next, the polymerization solution was withdrawn from the container and diluted with 20 L of MeOH. This solution was fed from the top of a column-type container, and MeOH vapor was fed from the bottom of the column to remove any unreacted monomers remaining in the polymerization solution along with the MeOH vapor, thereby obtaining an MeOH solution of ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as EVAc).

[0142] Next, 150 kg of a 20% by mass MeOH solution of EVAc was charged into a 300 L reaction vessel equipped with a jacket, stirrer, nitrogen inlet, reflux condenser, and solution addition port. The temperature of this solution was raised to 60°C while blowing nitrogen gas into it, and a 2 N sodium hydroxide MeOH solution was added at a rate of 450 mL / min for 2 hours. After the addition of the sodium hydroxide MeOH solution was completed, the temperature in the system was maintained at 60°C, and the saponification reaction was allowed to proceed by stirring for 2 hours while draining the MeOH and methyl acetate produced in the saponification reaction out of the reaction vessel. After that, 8.7 kg of acetic acid was added to stop the saponification reaction.

[0143] Subsequently, while heating and stirring at 80°C, 120 L of deionized water was added to drain MeOH from the reaction vessel and precipitate EVOH. The EVOH precipitated by decantation was collected and pulverized using a pulverizer. The obtained EVOH powder was placed in a 1 g / L aqueous acetic acid solution (bath ratio 20: 20 L of aqueous solution per 1 kg of powder) and stirred and washed for 2 hours. This was then dehydrated and placed in another 1 g / L aqueous acetic acid solution (bath ratio 20) and stirred and washed for 2 hours. The dehydrated mixture was then placed in deionized water (bath ratio 20), stirred and washed for 2 hours, and dehydrated. This process was repeated three times to purify the EVOH. The electrical conductivity of the washing solution was 3 μS / cm (measured with "CM-30ET" from Toa Denpa Kogyo Co., Ltd.). Next, the purified product 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 for 4 hours with stirring, then drained, and dried at 60°C for 16 hours to obtain 16.1 kg of crude dried EVOH.

[0144] The above procedure for synthesizing EVOH was repeated to obtain 15.9 kg of crude dried EVOH, resulting in a total of 32.0 kg of crude dried EVOH(A1). The ethylene unit content, degree of saponification, and melting point of the crude dried EVOH(A1) were measured according to the methods described in evaluation methods (1) and (10) above. The results are shown in Table 2.

[0145] <Synthesis Examples 2-8> The size of the pressurized reaction vessel, the amounts of VAc and MeOH charged, the ethylene pressure, the amount of polymerization initiator added, the temperature inside the reaction vessel (temperature during polymerization), the reaction time, the conversion rate of VAc, the amount of EVAc MeOH solution charged in the saponification step, and the rate of addition of sodium hydroxide MeOH solution are as shown in Table 1. Except that the synthesis was performed only once, the crude dried products of each EVOH(A2) to EVOH(A8) were obtained in the same manner as in Synthesis Example 1. The ethylene unit content, degree of saponification, and melting point of the crude dried products of EVOH(A2) to EVOH(A8) were measured according to the methods described in Evaluation Methods (1) and (10) above. The results are shown in Table 2.

[0146] [Table 1]

[0147] [Table 2]

[0148] <Reference example 1> In a 60L stirring tank equipped with a jacket, stirrer, and reflux condenser, 2 kg of the crudely 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 until completely dissolved. Sorbic acid, crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal were added to the resulting solution. This solution was extruded through a 4 mm diameter gold plate into a water / MeOH = 90 / 10 mixture cooled to -5°C to precipitate in strand form, and these strands were cut into pellets with a strand cutter to obtain hydrated EVOH pellets. The moisture content of the obtained hydrated EVOH pellets was measured using a Mettler halogen moisture meter "HR73" and was found to be 52% by mass.

[0149] The obtained hydrated EVOH pellets were placed in a 1 g / L aqueous acetic acid solution (bath ratio 20) and stirred and washed for 2 hours. After desaturation, the pellets were placed again in a 1 g / L aqueous acetic acid solution (bath ratio 20) and stirred and washed for 2 hours. After desaturation, the aqueous acetic acid solution was replaced and the same procedure was repeated. The pellets washed in aqueous acetic acid solution and then desaturated were placed in deionized water (bath ratio 20) and stirred and washed for 2 hours, and desaturated. This process was repeated three times until the electrical conductivity of the washing solution was 3 μS / cm or less (measured with Toa Denpa Kogyo Co., Ltd.'s "CM-30ET"), thereby obtaining hydrated EVOH pellets from which the catalyst residue from the saponification reaction had been removed.

[0150] The obtained 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 immersed for 4 hours with periodic stirring to perform chemical treatment. These pellets were dehydrated 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 vol% or less to obtain cylindrical (average diameter 2.8 mm, average height 3.2 mm) dried resin composition pellets containing EVOH(A1), acetic acid, phosphoric acid, sodium ions (sodium salt), crotonaldehyde, 2,4-hexadienal, 2,4,6-octatrienal, and sorbic acid. The obtained dried resin composition pellets were evaluated according to the methods described in evaluation methods (2) to (9) above. The sodium ion content in the dried resin composition pellets was 100 ppm, the phosphoric acid content was 40 ppm (calculated as phosphate root), and the acetic acid content was 200 ppm. The content of each component other than EVOH is based on the EVOH content. Other evaluation results are shown in Table 3. The amounts of each component added were adjusted so that the content of crotonaldehyde, 2,4-hexadienal, 2,4,6-octatrienal, and sorbic acid were as shown in Table 3.

[0151] [Reference Examples 2-61, Reference Comparative Examples 1-4, 6-24] Dry resin composition pellets were prepared and evaluated in the same manner as in Reference Example 1, except that the types of EVOH (A), unsaturated aliphatic aldehydes (B), conjugated polyene compounds (C), and boric acid content were adjusted to match those shown in Tables 3 to 10. For the 800 ppm boric acid content, an aqueous solution containing sodium acetate, etc. (bath ratio 20) was prepared to a boric acid concentration of 0.25 g / L. For the 1800 ppm boric acid content, an aqueous solution containing sodium acetate, etc. (bath ratio 20) was prepared to a boric acid concentration of 0.57 g / L. The sodium ion content of EVOH in each dry resin composition pellet was 100 ppm, the phosphoric acid content was 40 ppm (based on phosphate root), and the acetic acid content was 200 ppm. Other evaluation results are shown in Tables 3 to 10. The content of each component other than EVOH is based on the EVOH content.

[0152] <Reference Example 5> Dry resin composition pellets were prepared and evaluated in the same manner as in Reference Example 1, except that crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal were not added, and the catalyst residue from the saponification reaction had been removed. The hydrated EVOH pellets were placed in methanol (bath ratio 10), stirred and washed for 2 hours, and dehydrated. This process was repeated twice, and the resulting pellets were placed in ion-exchanged water (bath ratio 20), stirred and washed for 2 hours, and dehydrated. This process was repeated three times. The sodium ion content in the dry resin composition pellets was 100 ppm, the phosphoric acid content was 40 ppm (based on phosphate root), and the acetic acid content was 200 ppm. The content of each component other than EVOH is based on the EVOH content. Other evaluation results are shown in Table 3. The content of crotonaldehyde, 2,4-hexadienal, 2,4,6-octatrienal, and sorbic acid was below the detection limit.

[0153] [Table 3]

[0154] [Table 4]

[0155] [Table 5]

[0156] [Table 6]

[0157] [Table 7]

[0158] [Table 8]

[0159] [Table 9]

[0160] [Table 10]

[0161] From the reference examples and reference comparison examples, it can be seen that when b1 / (b2+b3) is between 2.0 and less than 150.0, neck-in resistance is good, the smaller b1+b2+b3 is, the lower the YI, the lower the content of the conjugated polyene compound (C) c, the lower the YI, and when b2+2b3 is 0.65 ppm or less, die build-up is suppressed.

[0162] A more detailed examination based on Table 3 reveals the following: Reference Comparative Example 5, which does not contain unsaturated aliphatic aldehyde (B), and Reference Comparative Examples 1-3 and 6-9, which contain various unsaturated aliphatic aldehydes (B) individually, do not suppress neck-in. Similarly, Reference Comparative Example 10, where the value of b1 / (b2+b3) is less than 2.0, also does not suppress neck-in. On the other hand, as can be seen from the reference examples, neck-in is suppressed when the value of b1 / (b2+b3) is in the range of 2.0 or more and less than 150.0, and in particular, neck-in is most suppressed when the value of b1 / (b2+b3) is around 10 (for example, 8.0 or more and 13.0 or less), as in Reference Examples 4, 5, 13, 14, 21, and 24. Furthermore, in Comparative Example 4, where b2+2b3 exceeds 0.65 ppm, dye buildup is not suppressed, whereas, as can be seen from the reference examples, when b2+2b3 is 0.65 ppm or less, dye buildup is suppressed, and in particular, when b2+2b3 is 0.10 ppm or less, dye buildup is suppressed more effectively. In addition, regarding the total content of crotonaldehyde (B1), 2,4-hexadienal (B2), and 2,4,6-octatrienal (B3), b1+b2+b3, as can be seen from Comparative Example 4, Reference Examples 1-7, 12-26, etc., it can be seen that the lower the total content, the better the hue. Furthermore, from Reference Examples 6, 9-11, it can be seen that a smaller content of conjugated polyene compounds results in better hue.

[0163] <Preparation of a resin composition containing antioxidant (G)> [Example 1] 100 parts by mass of the dry resin composition pellets obtained in Reference Example 5 and 0.5 parts by mass of N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (BASF Japan's "Irganox 1098", molecular weight: 637) as an antioxidant were dry blended and extruded at an extrusion temperature of 220°C under a nitrogen atmosphere using a 30 mmφ co-directional twin-screw extruder (Japan Steel Works Ltd. "TEX-30N") to obtain resin composition pellets.

[0164] [Examples 2, 4-7, Comparative Examples 1-3] Except for using the amounts of dried resin composition pellets and antioxidants shown in Table 11, resin composition pellets for Examples 2, 4-7, and Comparative Examples 1-3 were obtained in the same manner as in Example 1.

[0165] [Example 3] The resin composition pellets were obtained by dry blending 90 parts by mass of the dried resin composition pellets obtained in Reference Example 48, 10 parts by mass of "Tafmer® MH7020" (manufactured by Mitsui Chemicals, Inc., maleic anhydride-modified ethylene-butene copolymer) as a thermoplastic elastomer (F-1), and 0.5 parts by mass of the above antioxidant (Irganox 1098), and then extruding under the following conditions. (Extruder conditions) • Equipment: 30mmφ twin-screw extruder L / D: 45.5 • Screw: Fully interlocking in the same direction • Extrusion temperature (°C): 220°C • Rotation speed: 200 rpm ·Discharge amount: 20kg / hr

[0166] The dried resin composition pellets obtained from the examples and comparative examples were evaluated according to the methods described in (5) to (9) and (11) to (13) above. The evaluation results are shown in Tables 11 and 12.

[0167] [Table 11]

[0168] [Table 12]

[0169] As shown in Tables 11 and 12, each resin composition in Examples 1 to 7 suppressed neck-in and die build-up, and the resulting molded articles exhibited excellent resistance to oxidation degradation. It was confirmed that molded articles usable at high temperatures for extended periods could be obtained from each resin composition in the examples. The resin composition of Comparative Example 1, where b2+2b3 was not 0.65 ppm or less, failed to suppress die build-up, and the resin composition of Comparative Example 2, where b1 / (b2+b3) was not 2.0 or more and less than 150.0, exhibited poor neck-in resistance. The resin composition of Comparative Example 3, which did not contain a predetermined amount of antioxidant, showed low resistance to oxidation degradation and poor gas barrier properties after heat treatment in the resulting molded articles (single-layer films or pipes). Furthermore, the results from each reference example show that when b1 / (b2+b3) is between 2.0 and less than 150.0, neck-in resistance is good, and when b2+2b3 is 0.65 ppm or less, die build-up is suppressed. Therefore, it can be inferred that any resin composition obtained by adding a predetermined amount of antioxidant to the resin composition of each reference example will exhibit the same effects as the resin compositions of Examples 1 to 7.

Claims

1. It contains an ethylene-vinyl alcohol copolymer (A) having an ethylene unit content of 20 mol% or more and 60 mol% or less, crotonaldehyde (B1), and an antioxidant (G), It further comprises at least one selected from the group consisting of 2,4-hexadienal (B2) and 2,4,6-octatrienal (B3), The following equations (1) and (2) are satisfied, A resin composition having an antioxidant (G) content of 0.01% by mass or more and 5% by mass or less. 2.0≦b １ / (b ２ +b ３ )<150.0 ・・・(1) b ２ +2b ３ ≦0.65 ・・・(2) In the above formulas (1) and (2), b １ This is the content (ppm) of crotonaldehyde (B1) in ethylene-vinyl alcohol copolymer (A), and b ２ This is the content (ppm) of 2,4-hexadienal (B2) in ethylene-vinyl alcohol copolymer (A), and b ３ This is the content (ppm) of 2,4,6-octatrienal (B3) relative to the ethylene-vinyl alcohol copolymer (A).

2. The total content (b １ + b ２ + b ３ ) of crotonaldehyde (B1), 2,4 - hexadienal (B2) and 2,4,6 - octatrieneal (B3) with respect to the ethylene - vinyl alcohol copolymer (A) is 0.01 ppm or more and 7.0 ppm or less. The resin composition according to claim 1.

3. Crotonaldehyde (B1) content b １ The resin composition according to claim 1 or 2, wherein the concentration is 0.01 ppm or more and 4.0 ppm or less.

4. Content of 2,4-hexadienal (B2) ２ The resin composition according to claim 1 or 2, wherein the concentration is 0.005 ppm or more and 0.65 ppm or less.

5. Content of 2,4,6-octatrienal (B3) ３ The resin composition according to claim 1 or 2, wherein the amount is 0.325 ppm or less.

6. The resin composition according to claim 1 or 2, further comprising a conjugated polyene compound (C), wherein the content c of the conjugated polyene compound (C) relative to the ethylene-vinyl alcohol copolymer (A) is 1 ppm or more and less than 300 ppm.

7. The resin composition according to claim 6, wherein the conjugated polyene compound (C) is sorbic acid.

8. It further contains a thermoplastic elastomer (F), The resin composition according to claim 1 or 2, wherein the mass ratio (F / A) of the thermoplastic elastomer (F) to the ethylene-vinyl alcohol copolymer (A) is 5 / 95 or more and 35 / 65 or less.

9. The resin composition according to claim 8, wherein the thermoplastic elastomer (F) is at least one selected from the group consisting of polyester-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, and polyolefin-based thermoplastic elastomers.

10. A molded article having a portion made of the resin composition according to claim 1 or 2.

11. A laminate having at least one layer made of the resin composition described in claim 1 or 2.

12. A pipe having a layer made of the resin composition according to claim 1 or 2.

13. A hot water circulation pipe comprising the pipe described in claim 12.

14. An insulated multilayer pipe comprising the pipe according to claim 12, further comprising an insulating foam layer.

15. A fuel pipe comprising the pipe described in claim 12.

Images