JP2015071696A - Ethylene-vinyl alcohol resin composition, multilayer structure, multilayer sheet, container, and packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition having excellent retort resistance and a property to suppress occurrence of scorch and odor during long time operation of a molding machine.SOLUTION: Provided is a resin composition comprising an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 mole% or more and 60 mole% or less, a polyamide (B), a carboxylic acid metal salt (C), and a saturated aldehyde (D). In the resin composition, a mass ratio (A/B) of the ethylene-vinyl alcohol copolymer (A) to the polyamide (B) is 60/40 or more and 95/5 or less; a content of the carboxylic acid metal salt (C) relative to the resin content is, in terms of a metal element, 1 ppm or more and 500 ppm or less; and a content of the saturated aldehyde (D) relative to the resin content is 0.01 ppm or more and 100 ppm or less. The content of the carboxylic acid metal salt (C) relative to the resin content is, in terms of a metal content, preferably 5 ppm or more.

Description

  The present invention relates to a resin composition containing an ethylene-vinyl alcohol copolymer, polyamide, a carboxylic acid metal salt and a saturated aldehyde, a multilayer structure and a multilayer sheet using the resin composition, and a container and a package using the multilayer sheet. Regarding materials.

  An ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as “EVOH”) is a useful polymer material excellent in various gas shielding properties such as oxygen, oil resistance, non-charging property, mechanical strength, etc. It is formed into a film, a sheet, a container, a packaging material and the like and widely used as various packaging materials. In particular, it is known that a laminate comprising an EVOH layer and another thermoplastic resin layer is useful as a packaging material for boil sterilization of food or for retort sterilization.

  However, when it is used for hot water boil sterilization or retort sterilization that is generally used, water penetrates into the EVOH layer during processing, and the mechanical properties of the EVOH layer deteriorate. As this improvement method, a method in which EVOH is blended with polyamide having high hot water resistance (hereinafter sometimes abbreviated as “PA”) has been adopted (hereinafter referred to as suitability for boil sterilization or retort sterilization. Today, as a method for further improving the retort resistance, a resin composition layer having an EVOH / PA mass ratio of 55/45 to 97/3 is used as the outermost layer, and the inner layer has a low permeability. A method of laminating a wet thermoplastic resin (see Japanese Patent Laid-Open No. 10-80981), a method of containing a metal compound or a boric acid compound in an intermediate layer made of a composition containing EVOH and PA (Japanese Patent Laid-Open No. 4-131237) And a method using a composition composed of two kinds of EVOH and PA (see JP-A-6-23924) has been developed.

  However, in the resin composition containing EVOH and PA, a crosslinking reaction proceeds between the hydroxyl group or terminal carboxyl group of EVOH and the amide group, terminal amino group or terminal carboxyl group of PA, and the resin viscosity is uneven. As a result, the occurrence of kogation in the extruder, screw and die becomes remarkable during long-time melt molding.

  Such kogation in the extruder, screw and die may be mixed into the molded article during continuous operation for a long time after staying for a certain period of time. Thus, the koge mixed into the molded product not only impairs the appearance but also causes defects due to this, resulting in various mechanical properties being lowered. In order to prevent such kogation from being mixed into the molded product, it is usually necessary to periodically stop the operation and to disassemble and clean the series of extrusion equipment. However, the increase in the frequency of this work leads not only to an increase in manufacturing cost, but also to consumption of materials required for stopping and restarting, and loss of manufacturing time. Therefore, improvements are required from both the resource and cost viewpoints. .

  However, although the technique of the above document improves the retort resistance, it is still insufficient from the viewpoint of suppressing the generation of kogation in the molding machine during long-time operation.

  As described above, it is difficult for the conventional technology to improve both the retort resistance of the resin composition and the improvement of the appearance defect caused by the kogation during long-time operation. In addition, from the environmental point of view, it is necessary to consider the odor during molding.

Japanese Patent Laid-Open No. 10-80981 JP-A-4-131237 Japanese Patent Laid-Open No. 6-23924 JP 2007-31725 A

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a resin composition which is excellent in both retort resistance, kogation during long-time operation, and odor control. .

  The invention made in order to solve the above-mentioned problems includes an ethylene-vinyl alcohol copolymer (A) (hereinafter also referred to as “EVOH (A)”) having an ethylene content of 20 mol% to 60 mol%, polyamide ( B) (hereinafter also referred to as “PA (B)”), a carboxylic acid metal salt (C) and a saturated aldehyde (D), and the mass of the ethylene-vinyl alcohol copolymer (A) relative to the polyamide (B). The ratio (A / B) is 60/40 or more and 95/5 or less, the content of the carboxylic acid metal salt (C) with respect to the resin content is 1 ppm or more and 500 ppm or less in terms of metal element, and the saturated aldehyde (D) The resin composition has a content of 0.01 ppm to 100 ppm with respect to the resin content.

  The resin composition contains the components (A) to (D), the content ratio of the ethylene-vinyl alcohol copolymer (A) and the polyamide (B), the content of the carboxylic acid metal salt (C), and By making content of saturated aldehyde (D) into the said specific range, both retort resistance, the kog generation | occurrence | production at the time of long-time driving | operation, and the suppression property of an odor are excellent. The reason why the resin composition exhibits the above-mentioned effects is not necessarily clear, but, for example, an ethylene-vinyl alcohol copolymer (A), a polyamide (B) that improves hot water resistance, and a gel-like powder during long-time operation. By containing the carboxylic acid metal salt (C) that suppresses the generation of slag and the saturated aldehyde (D) that suppresses the generation of kogation in the molding machine during a long-time operation, respectively, the content of each of these components It is estimated that the effect is demonstrated synergistically, and as a result, the generation of kogation in the molding machine during long-time operation can be effectively suppressed while maintaining and improving the retort resistance, and the continuous production operation time can be extended. Is done.

  The content of the carboxylic acid metal salt (C) with respect to the resin content is preferably 5 ppm or more in terms of metal element. In the resin composition, the content of the carboxylic acid metal salt (C) is within the specific range, so that the occurrence of gelled blisters during long-time operation can be further suppressed. The generation of kogation can be further suppressed, and the retort resistance and the appearance defect can be further improved.

  As the metal element of the carboxylic acid metal salt (C), magnesium, calcium and zinc are preferable. Thus, by making carboxylic acid metal salt (C) the thing of the said specific metal element, generation | occurrence | production of the gel-like spot at the time of long-time driving | operation can be further suppressed, As a result, generation | occurrence | production of kogation is further suppressed. In addition, the retort resistance can be further improved.

  The saturated aldehyde (D) preferably has 3 to 8 carbon atoms, more preferably propanal, butanal, or hexanal. By using the specific saturated aldehyde as the saturated aldehyde (D), it is possible to further improve the above-mentioned kogation inhibitory property and retort resistance.

  The multilayer structure of this invention is equipped with the barrier layer formed from the said resin composition, and the thermoplastic resin layer laminated | stacked on the at least one surface of this barrier layer. Moreover, the multilayer sheet of the present invention comprises the multilayer structure. The multilayer structure and the multilayer sheet are excellent in appearance, retort resistance, and processability by including a barrier layer formed from the resin composition having the above-described characteristics and a thermoplastic resin layer.

  The barrier layer and the thermoplastic resin layer may be laminated by a coextrusion molding method. The multilayer sheet can be easily and reliably manufactured by laminating the two kinds of layers by the coextrusion molding method, and as a result, the excellent appearance, retort resistance and processing characteristics are effectively obtained. Can be achieved.

  In the container of the present invention, the multilayer sheet may be formed by a vacuum / pressure forming method. The container can be easily and reliably manufactured by using the above-described multilayer sheet and forming by a vacuum / pressure forming method. As a result, the container has excellent appearance and retort resistance.

  The container may be for boil sterilization or retort sterilization. Since the said container uses the resin composition which has the above-mentioned property, it can be used suitably for the said use.

  In the packaging material of the present invention, the multilayer sheet may be formed by a hot stretch forming method. The packaging material can be easily and reliably manufactured by using the above-described multilayer sheet by the heat stretch molding method, and as a result, the packaging material composed of the multilayer sheet after stretching has excellent appearance, In addition, the occurrence of stretch spots is suppressed.

  Here, the “resin component” refers to the total resin component composed of EVOH (A) and PA (B) and other resins that may be contained as optional components described later.

  As described above, the resin composition of the present invention can effectively suppress the occurrence of kogation in the molding machine during long-time operation, and therefore, a molded article having excellent appearance, retort resistance, and mechanical strength is produced. Can do. The multilayer structure and multilayer sheet of the present invention are excellent in appearance, retort resistance and processing characteristics. The container of the present invention is excellent in appearance and retort resistance. The packaging material of the present invention is excellent in appearance and the occurrence of stretch spots is suppressed. Therefore, the resin composition, multilayer structure, multilayer sheet, container and packaging material are suitable as various packaging materials for boil sterilization or retort sterilization.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto. Moreover, as long as there is no description in particular, the material illustrated may be used individually by 1 type, and may use 2 or more types together.

<Resin composition>
The resin composition contains EVOH (A), PA (B), carboxylic acid metal salt (C), and saturated aldehyde (D). The resin composition may contain an optional component such as a boron compound, a conjugated polyene compound, acetic acid, and a phosphorus compound as long as the effects of the present invention are not impaired. Hereinafter, each component will be described.

[EVOH (A)]
EVOH (A) is an ethylene-vinyl alcohol copolymer obtained by saponifying a copolymer of ethylene and vinyl ester.

  Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl pivalate and the like, and vinyl acetate is preferable. These vinyl esters may be used alone or in combination of two or more.

  EVOH (A) may contain other structural units derived from monomer units other than ethylene and vinyl ester. Examples of such monomer units include vinyl silane compounds and other polymerizable compounds. As content of said other structural unit, 0.0002 mol% or more and 0.2 mol% or less are preferable with respect to all the structural units of EVOH (A), for example.

  Examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloxypropyltrimethoxysilane. Among these, vinyltrimethoxysilane and vinyltriethoxysilane are preferable.

  Examples of the other polymerizable compounds include unsaturated hydrocarbons such as propylene and butylene; unsaturated carboxylic acids such as (meth) acrylic acid; and vinylpyrrolidones such as N-vinylpyrrolidone.

  The ethylene content of EVOH (A) is from 20 mol% to 60 mol%, preferably from 24 mol% to 55 mol%, more preferably from 27 mol% to 45 mol%, more preferably from 27 mol% to 42 mol%. The mol% or less is more preferable, and 27 mol% or more and 38 mol% or less is particularly preferable. When the ethylene content is less than the above lower limit, the thermal stability at the time of melt extrusion is lowered and gelation tends to occur, and defects such as streak and fish eye are likely to occur. In particular, if the operation is performed for a long time at a higher temperature or at a higher speed than the general melt extrusion conditions, the possibility of gelation increases. On the other hand, when the ethylene content exceeds the above upper limit, gas barrier properties and the like are lowered, and there is a possibility that the advantageous characteristics possessed by EVOH cannot be sufficiently exhibited.

  The saponification degree of the structural unit derived from the vinyl ester of EVOH (A) is usually 85% or more, preferably 90% or more, more preferably 98% or more, and further preferably 99% or more. If the degree of saponification is less than 85%, the thermal stability may be insufficient.

[PA (B)]
PA (B) is a resin containing an amide bond. PA (B) is obtained by ring-opening polymerization of a lactam having three or more members, polycondensation of a polymerizable ω-amino acid, polycondensation of a dibasic acid and a diamine, or the like.

  In PA (B), aromatic diamines such as aliphatic diamines, methylbenzylamines, metaxylylenediamines, etc. introduced with substituents such as 2,2,4- and 2,4,4-trimethylhexamethylenediamine as diamines, etc. May be used, and these may be used to modify the polyamide. Further, aliphatic carboxylic acids into which substituents such as 2,2,4- and 2,4,4-trimethyladipic acid are introduced as dicarboxylic acids, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, and phthalic acid An aromatic dicarboxylic acid such as xylylene dicarboxylic acid, alkyl-substituted terephthalic acid, alkyl-substituted isophthalic acid, and naphthalenedicarboxylic acid may be used, and these may be used to modify the polyamide.

  Examples of PA (B) include polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecanamide (nylon 11), polylauryl lactam (nylon). 12), polyethylenediamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodeca Mido (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 106), caprolactam / lauryl lactam copolymer (nylon 6/12), caprolactam / ω-aminononanoic acid copolymer Coalescence (nylon 6/9), cap Loractam / hexamethylene diammonium adipate copolymer (nylon 6/66), lauryl lactam / hexamethylene diammonium adipate copolymer (nylon 12/66), hexamethylene diammonium adipate / hexamethylene diammonium sebacate copolymer (Nylon 66/610), ethylenediammonium adipate / hexamethylenediammonium adipate copolymer (nylon 26/66), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6/66 / 610), polyhexamethylene isophthalamide (nylon 6I), polyhexamethylene terephthalamide (nylon 6T), hexamethylene isophthalamide / terephthala De copolymer (nylon 6I / 6T), and the like. These PA (B) s may be used alone or in the form of a mixture of two or more.

  Among these PA (B), polycapramide (nylon 6) and caprolactam / lauryl lactam copolymer (nylon 6/12) are preferable. Although the content ratio of 6 units and 12 units is not specifically limited, 5 mass%-60 mass% are preferable as a content rate of 12 units, and 5 mass%-50 mass% are more preferable.

  The content ratio of EVOH (A) and PA (B) in the resin composition is 60/40 as the lower limit of the mass ratio of EVOH (A) to PA (B), preferably 65/35, 70 / 30 is more preferable, and 75/25 is particularly preferable. Moreover, as an upper limit of this mass ratio, it is 95/5, 90/10 is preferable and 85/15 is more preferable. If this mass ratio is less than the above lower limit, EVOH (A) may have inherently various properties such as gas shielding properties and oil resistance. Conversely, when the mass ratio exceeds the upper limit, the retort resistance of the resin composition may be reduced.

  The total mass of EVOH (A) and PA (B) with respect to the resin content in the resin composition is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and 100% by mass. Particularly preferred.

[Carboxylic acid metal salt (C)]
The resin composition contains a carboxylic acid metal salt (C). By containing the carboxylic acid metal salt (C), the resin composition can suppress the occurrence of gelled blisters during long-time operation.

  Although it does not specifically limit as a metal element of carboxylic acid metal salt (C), From a viewpoint of the inhibitory effect of gel-like stuff, the metal which forms bivalent metal salts, such as magnesium, calcium, barium, beryllium, zinc, copper, for example Examples of the element include magnesium, calcium, and zinc.

  The anion of the carboxylic acid metal salt (C) is not particularly limited as long as it is a carboxylic acid anion. For example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid Carboxylic acid anions such as undecanoic acid, dodecanoic acid, stearic acid, dimethyldithiocarbamic acid, palmitic acid, 2-ethylhexanoic acid, neodecanoic acid, linoleic acid, toluic acid, oleic acid, capric acid, and naphthenic acid.

  As carboxylic acid which comprises a carboxylic acid anion, C1-C26 carboxylic acid is preferable, C1-C12 is more preferable, C1-C9 is more preferable, and an acetic acid is especially preferable.

  The lower limit of the content of the carboxylic acid metal salt (C) relative to the resin content is 1 ppm in terms of metal element, preferably 3 ppm, more preferably 5 ppm, and even more preferably 10 ppm. As an upper limit of the said content of carboxylic acid metal salt (C), it is 500 ppm in conversion of a metal element, 350 ppm is preferable, 200 ppm is more preferable, 150 ppm is further more preferable. When the content is less than the lower limit, the effect of suppressing gel-like irregularities during long-time operation of the resin composition becomes insufficient. When the content exceeds the upper limit, coloring of the resin composition becomes remarkable, deterioration due to decomposition reaction is promoted, and EVOH having an appropriate melt viscosity cannot be obtained. May decrease and it may be difficult to obtain a desired molded article. Here, the content of the carboxylic acid metal salt (C) in the resin composition is a ratio with respect to the resin content in the resin composition, that is, a mass ratio in terms of a metal element with respect to the total mass of the resin component. Specifically, it refers to the ratio relative to the resin content in the dried resin composition. The said resin composition may use carboxylic acid metal salt (C) individually by 1 type or in combination of 2 or more types.

[Saturated aldehyde (D)]
Since the resin composition of the present invention contains a saturated aldehyde (D), it is possible to effectively suppress kogation in the molding machine during long-time operation, and to provide a molded article excellent in appearance, retort resistance and mechanical strength. Can be manufactured. Here, the saturated aldehyde (D) refers to an aldehyde that does not contain an unsaturated bond in a portion other than the aldehyde group in the molecule. Saturated aldehyde (D) is an aldehyde having a ring structure in the molecule, whether it is a straight chain aldehyde or a branched aldehyde, as long as it contains no unsaturated bond in a portion other than the aldehyde group. It may be. The number of aldehyde groups in the molecule of the saturated aldehyde (D) may be 1 or 2 or more.

  Examples of the saturated aldehyde (D) include a saturated aliphatic aldehyde.

  Examples of saturated aliphatic aldehydes include acetaldehyde, propanal, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, cyclohexanecarbaldehyde, cyclooctanecarbaldehyde, cyclopentylaldehyde, methylcyclohexanecarbaldehyde, methylcyclopentylaldehyde, and the like. It is done.

  As carbon number of saturated aldehyde (D), from a viewpoint of the water solubility improvement of saturated aldehyde (D), 3-50 are preferable, 3-15 are more preferable, and 3-8 are more preferable. Among the exemplified saturated aldehydes (D), propanal, butanal, and hexanal are preferable, and propanal is more preferable from the viewpoint of suppressing generation of defects and coloring due to melt molding and improving long run properties.

  In the saturated aldehyde (D), part or all of the hydrogen atoms may be substituted with a substituent as long as the effects of the present invention are not impaired. Examples of the substituent include a halogen atom, a hydroxy group, an amino group, an amide group, and a cyano group.

  The lower limit of the content of the saturated aldehyde (D) is 0.01 ppm, preferably 0.05 ppm, and more preferably 0.1 ppm with respect to the resin content. Moreover, as an upper limit of content of saturated aldehyde (D), it is 100 ppm with respect to a resin content, 95 ppm is preferable and 50 ppm is more preferable. When the content is less than the lower limit, the suppression of kogation in the molding machine is insufficient. If the content exceeds the above upper limit, the resin composition may be cross-linked by the saturated aldehyde (D) during melt molding, inducing the formation of gelled blisters, and easily colored. Here, the content of the saturated aldehyde (D) in the resin composition is a ratio with respect to the resin content in the resin composition, that is, a mass ratio with respect to the total mass of the resin components. The ratio of the saturated aldehyde (D) with respect to the resin part in the made said resin composition is said.

[Optional ingredients]
(Boron compound)
The boron compound suppresses gelation during melt molding and suppresses torque fluctuations (viscosity change during heating) of an extruder or the like.

Examples of the boron compound include boric acids such as orthoboric acid, metaboric acid, and tetraboric acid; boric acid esters such as triethyl borate and trimethyl borate;
Borate salts such as alkali metal salts or alkaline earth metal salts of borates, borax;
Examples thereof include borohydrides. Among these, boric acids are preferable, and orthoboric acid is more preferable.

  As a minimum of content of the boron compound of the resin composition, 100 ppm is preferred and 150 ppm is more preferred. The upper limit of the boron compound content is preferably 5,000 ppm, more preferably 4,000 ppm, and even more preferably 3,000 ppm. If the boron compound content is less than the above lower limit, torque fluctuations in an extruder or the like may not be sufficiently suppressed. On the other hand, if the content of the boron compound exceeds the above upper limit, gelation is likely to occur during melt molding, and the appearance of the molded product may be deteriorated.

(Conjugated polyene compound)
The conjugated polyene compound suppresses oxidative degradation during melt molding. Here, the conjugated polyene compound is a so-called conjugated double compound having a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately connected and having two or more carbon-carbon double bonds. A compound having a bond. This conjugated polyene compound may be a conjugated diene having two conjugated double bonds, a conjugated triene having three, or a conjugated polyene having more than that number. Further, a plurality of sets of the conjugated double bonds may be present in one molecule without being conjugated with each other. For example, a compound having three conjugated triene structures in the same molecule such as tung oil is also included in the conjugated polyene compound.

  The number of conjugated double bonds in the conjugated polyene compound is preferably 7 or less. When the resin composition contains a conjugated polyene compound having 8 or more conjugated double bonds, the molded product is highly likely to be colored.

  In addition to conjugated double bonds, the conjugated polyene compounds include carboxyl groups and salts thereof, hydroxyl groups, ester groups, carbonyl groups, ether groups, amino groups, imino groups, amide groups, cyano groups, diazo groups, nitro groups, sulfones. It may have other functional groups such as a group and a salt thereof, a sulfonyl group, a sulfoxide group, a sulfide group, a thiol group, a phosphate group and a salt thereof, a phenyl group, a halogen atom, a double bond, and a triple bond.

Examples of the conjugated polyene compound 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, 3-ethyl-1,3-pentadiene, 2- Methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexadiene, 2,4-hexadiene, 2,5-dimethyl-2,4- Hexadiene, 1,3-octadiene, 1,3-cyclopentadiene, 1,3-cyclohexadiene, 1-phenyl-1,3-butadiene, 1,4-diphenyl-1,3-butyl Tadiene, 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 Butadiene, chloroprene, 1-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-bromo-1,3-butadiene, oxime, ferrandrene, myrcene, farnesene, sorbic acid, sorbic acid ester, Conjugated diene compounds such as sorbate;
Conjugated triene compounds such as 1,3,5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil, cholecalciferol, fulvene, and tropone;
Examples thereof include conjugated polyene compounds such as cyclooctatetraene, 2,4,6,8-decatetraene-1-carboxylic acid, retinol, and retinoic acid. The said conjugated polyene compound may be used individually by 1 type, and may use 2 or more types together.

  As carbon number of a conjugated polyene compound, 4-30 are preferable and 4-10 are more preferable. Among the exemplified conjugated diene compounds, sorbic acid, sorbic acid ester, sorbate, myrcene, and a mixture of two or more thereof are preferable, and sorbic acid, sorbate, and a mixture thereof are more preferable. Sorbic acid, sorbate and a mixture thereof are highly effective in suppressing oxidative degradation at high temperatures, and are also widely used industrially as food additives, and thus are preferable from the viewpoint of hygiene and availability.

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

  As a minimum of content of a conjugated polyene compound in the resin composition, 0.01 ppm is preferred, 0.1 ppm is more preferred, 0.5 ppm is still more preferred, and 1 ppm is especially preferred. The upper limit of the content is preferably 1,000 ppm, more preferably 800 ppm or less, and even more preferably 500 ppm or less. If the content of the conjugated polyene compound is less than the above lower limit, the effect of suppressing oxidative deterioration during melt molding may not be sufficiently obtained. On the other hand, when the content of the conjugated polyene compound exceeds the upper limit, gelation of the resin composition may be promoted.

  Although it is disclosed in JP-A-9-71620 that a resin composition with less generation of gel-like spots at the time of molding can be obtained by adding a conjugated polyene compound in a post-polymerization step, In addition to the addition of the saturated aldehyde (D) in addition to the polyene compound, the generation of defects such as fish eyes and coloring can be further suppressed, and the appearance of the molded product can be improved. In addition, an excellent resin composition can be obtained.

(Acetic acid)
Acetic acids prevent coloring of the molded product and suppress gelation during the prevention melt molding. The acetic acids include acetic acid and acetate. As acetic acid, it is preferable to use acetic acid and acetate together, and it is more preferable to use acetic acid and sodium acetate together.

  As a minimum of content of acetic acid in the resin composition concerned, 50 ppm is preferred, 100 ppm is more preferred, 150 ppm is still more preferred, and 200 ppm is especially preferred. The upper limit of the acetic acid content is preferably 1,000 ppm, more preferably 500 ppm, and still more preferably 400 ppm. If the acetic acid content is less than the above lower limit, a sufficient anti-coloring effect cannot be obtained, and the molded product may be yellowed. On the other hand, if the content of acetic acid exceeds the above upper limit, gelation tends to occur during melt molding, particularly during long melt molding, and the appearance of the molded product may be deteriorated.

(Phosphorus compound)
The phosphorus compound suppresses generation and coloring of defects such as streaks and fish eyes and improves long run properties. Examples of the phosphorus compound include phosphates such as phosphoric acid and phosphorous acid.

  As said phosphate, any form of a 1st phosphate, a 2nd phosphate, and a 3rd phosphate may be sufficient. Moreover, although it does not specifically limit also about the cation seed | species of a phosphate, An alkali metal salt and alkaline-earth metal salt are preferable, Among these, sodium dihydrogen phosphate, potassium dihydrogen phosphate, hydrogen phosphate 2 Sodium and dipotassium hydrogen phosphate are more preferable, and sodium dihydrogen phosphate and dipotassium hydrogen phosphate are more preferable.

  As a minimum of content of a phosphorus compound in the resin composition, 1 ppm is preferred, 2 ppm is more preferred, 3 ppm is still more preferred, and 5 ppm is especially preferred. As an upper limit of content of a phosphorus compound, 200 ppm is preferable, 150 ppm is more preferable, and 100 ppm is further more preferable. When the content of the phosphorus compound is less than the above lower limit or exceeds the above upper limit, the thermal stability is reduced, and there is a risk that gelled spots and coloration are likely to occur during long-time melt molding. .

(Other optional ingredients)
The resin composition may contain other optional components as long as the effects of the present invention are not impaired. Other optional components include, for example, alkali metals or salts thereof, antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, heat stabilizers, other resins, and higher aliphatic carboxylic acids. And metal salts thereof. The resin composition may contain two or more of these optional components, and the total content of the optional components is preferably 1% by mass or less in the resin composition.

  Examples of the alkali metal include lithium, sodium, and potassium. Examples of the alkali metal salts include monovalent metal aliphatic carboxylates, aromatic carboxylates, metal complexes, and the like. Specifically, sodium acetate, potassium acetate, sodium stearate, Examples include potassium stearate and sodium salt of ethylenediaminetetraacetic acid. Among these, sodium acetate and potassium acetate are preferable. The alkali metal content in the resin composition is preferably 20 ppm to 1,000 ppm, more preferably 50 ppm to 500 ppm.

  Examples of the antioxidant include 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis (6-t-butylphenol), 2,2 '-Methylene-bis (4-methyl-6-t-butylphenol), octadecyl-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis (6 -T-butylphenol) and the like.

  Examples of the ultraviolet absorber include ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-). Methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-oxybenzophenone and the like.

  Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, and phosphate ester.

  Examples of the antistatic agent include pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, polyethylene glycol (trade name: carbowax) and the like.

  Examples of the lubricant include ethylene bisstearamide and butyl stearate.

  Examples of the colorant include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and bengara.

  Examples of the filler include glass fiber, wollastonite, calcium silicate, talc, and montmorillonite.

  Examples of the heat stabilizer include hindered phenol compounds and hindered amine compounds.

  Examples of the other resin include polyamide and polyolefin.

  Examples of the metal salt of the higher aliphatic carboxylic acid include calcium stearate and magnesium stearate.

  In addition, as a countermeasure against gelation, for example, hindered phenol compounds and hindered amine compounds exemplified as the heat stabilizer, metal salts of the higher fatty acid carboxylic acids, hydrotalcite compounds, and the like may be added. These may be used alone or in combination of two or more. The addition amount of the compound for preventing gelation is usually 0.01% by mass to 1% by mass.

<Method for producing resin composition>
The method for producing the resin composition is not particularly limited as long as EVOH (A), PA (B), carboxylic acid metal salt (C) and saturated aldehyde (D) can be blended uniformly. EVOH (A) is, for example, a step of copolymerizing ethylene and vinyl ester (hereinafter also referred to as “step (1)”), and a step of saponifying the copolymer obtained by this step (1) (hereinafter referred to as “step (1)”). (Also referred to as “step (2)”).

  The method for containing a specific amount of saturated aldehyde (D) in the resin composition is not particularly limited. For example, a method of adding a specific amount of saturated aldehyde (D) in step (1), specified in step (2) Examples include a method of adding an amount of saturated aldehyde (D), a method of adding a specific amount of saturated aldehyde (D) to EVOH (A) obtained in step (2), and the like.

  However, when employing a method of adding a specific amount of saturated aldehyde (D) in step (1) or a method of adding a specific amount of saturated aldehyde (D) in step (2), the resin composition obtained In order to contain a desired amount of saturated aldehyde (D), it is necessary to increase the amount of addition in consideration of the amount consumed in the polymerization reaction in step (1) or the saponification reaction in step (2). . However, if the amount of saturated aldehyde (D) is large, these reactions may be inhibited. Moreover, since the amount by which the saturated aldehyde (D) is consumed varies depending on the conditions of the polymerization reaction in the step (1) and the saponification reaction in the step (2), the content of the saturated aldehyde (D) in the resin composition It is difficult to adjust the amount. Therefore, a method of adding a specific amount of saturated aldehyde (D) to EVOH (A) obtained by this step (2) after step (2) is preferred.

  As a method for adding a specific amount of saturated aldehyde (D) to the resin, for example, a method in which a saturated aldehyde (D) is pre-blended with the resin and pellets are granulated, and precipitation is carried out after saponification of the ethylene-vinyl ester copolymer. A method for impregnating a saturated aldehyde (D) into a strand, a method for impregnating a saturated aldehyde (D) after cutting a strand to be precipitated, and a method for adding a saturated aldehyde (D) to a re-dissolved chip of a dry resin composition , A method of melt-kneading the resin and the saturated aldehyde (D), a method of supplying and containing the saturated aldehyde (D) to the resin melt from the middle of the extruder, a high concentration of the saturated aldehyde (D) in a part of the resin Examples thereof include a method of dry blending a compounded and granulated master batch with a resin and melt-kneading.

  Among these, from the viewpoint of uniformly dispersing a small amount of saturated aldehyde (D) in the resin, as a method of adding the saturated aldehyde (D), the saturated aldehyde (D) is previously blended into the resin and pelletized. The method of granulating is preferable. Specifically, the addition of the saturated aldehyde (D) is performed by adding the saturated aldehyde (D) to a solution obtained by dissolving the resin in a good solvent such as a water / methanol mixed solvent. It is preferable to carry out by extruding into a precipitate and solidifying it, washing and drying. In this case, the resin composition is obtained as pellets in which the saturated aldehyde (D) is uniformly mixed with the resin.

  Examples of a method of adding each component other than the saturated aldehyde (D) to the resin composition include, for example, a method of mixing and melting and kneading the pellet together with the components, and preparing the pellet together with the saturated aldehyde (D). The method of mixing each component, the method of immersing the said pellet in the solution containing each component, etc. are mentioned. In addition, a ribbon blender, a high speed mixer kneader, a mixing roll, an extruder, an intensive mixer, etc. can be used for mixing a pellet and another component.

<Molded body>
The resin molded body is formed from the resin composition. A film usually has a thickness of less than 300 μm, and a sheet usually has a thickness of 300 μm or more. As this resin molding, a film, a sheet | seat, a container, a pipe, a hose, a fiber, a packaging material etc. are mentioned, for example. The resin molded body is formed by, for example, melt molding, and is formed by performing secondary processing molding as necessary. Examples of the melt molding method include extrusion molding, inflation extrusion, blow molding, melt spinning, injection molding, and injection blow molding. The melt molding temperature is preferably about 150 ° C. to 270 ° C., although it varies depending on the melting point of EVOH (A). Examples of the secondary processing molding include bending, vacuum molding, blow molding, and press molding.

  The molded body may be a molded body having a single-layer structure consisting only of a barrier layer formed from the resin composition (hereinafter, also referred to as “barrier layer”). It is preferable to provide a multilayer structure including another layer laminated on at least one surface of the barrier layer. A multilayer structure is excellent in external appearance property, retort resistance, and a processing characteristic by providing a barrier layer and a thermoplastic resin layer.

Examples of the multilayer structure include multilayer sheets, multilayer pipes, multilayer fibers, and the like.
As another layer which comprises the said multilayer structure, the thermoplastic resin layer formed, for example from a thermoplastic resin is preferable. The multilayer structure is excellent in appearance and heat stretchability by including a barrier layer and a thermoplastic resin layer.

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

  Examples of the thermoplastic resin further include polyamide, polyester, polystyrene, polyvinyl chloride, acrylic resin, polyurethane, polycarbonate, and polyvinyl acetate.

  Among these, polyethylene, polypropylene, polyamide, and polyester are preferable as the thermoplastic resin. As a specific resin material for forming the thermoplastic resin layer, an unstretched polypropylene film and a nylon 6 film are preferable.

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

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

  Among these, as a method for producing a multilayer sheet, a coextrusion laminating method and a coextrusion molding method are preferable, and a coextrusion molding method is more preferable. By laminating the barrier layer and the thermoplastic resin layer by the above method, it can be produced easily and reliably, and as a result, high appearance, retort resistance and processing characteristics can be effectively achieved. .

  Examples of a method for forming a molded body using the multilayer sheet include a heat stretch forming method, a vacuum forming method, a pressure forming method, a vacuum / pressure forming method, and a blow forming method. These moldings are usually performed in a temperature range below the melting point of EVOH. Among these, the heat stretch molding method and the vacuum / pressure forming method are preferable. The heat stretch molding method is a method in which a multilayer sheet is heated and stretched in one direction or a plurality of directions. The vacuum / pressure forming method is a method in which a multilayer sheet is heated and formed using both vacuum and compressed air. As the molded body, a packaging material obtained by molding the above-described multilayer sheet by a heat stretch molding method can be easily and reliably manufactured, has excellent appearance, and stretch spots are suppressed. it can. Further, a container formed by forming the above-mentioned multilayer sheet by a vacuum / pressure forming method can be easily and reliably produced, and can be excellent in appearance and retort resistance. In addition, these packaging materials and containers can have flow marks suppressed.

  In the heat stretch molding method, the extruded multilayer sheet is preferably cooled immediately after extrusion and made as amorphous as possible. Next, the multilayer sheet is reheated within the range of not higher than the melting point of EVOH, and uniaxially or biaxially stretched by a roll stretching method, a pantograph stretching method, an inflation stretching method, or the like. The stretching ratio is 1.3 to 9 times, preferably 1.5 to 4 times in the longitudinal and / or lateral directions, and the heating temperature is 50 ° C to 140 ° C, preferably 60 ° C to 100 ° C. When the heating temperature is less than 50 ° C., the stretchability is deteriorated and the dimensional change is also increased.

  When the packaging material is produced from a multilayer sheet using a heat stretch molding method, the above-mentioned resin can be used as a thermoplastic resin to further improve the appearance and to suppress defects such as cracks. can do.

  Moreover, the said molded object can also be shape | molded by the co-injection stretch blow molding method using the said resin composition mentioned above and another resin composition. The co-injection stretch blow molding method is a method in which, for example, a preform having a multilayer structure is obtained by co-injection molding using two or more resin compositions, and then this preform is subjected to heat stretch blow molding. By molding by using the co-injection stretch blow molding method from the resin composition having the above-mentioned properties, the molded body can be easily and reliably produced, has excellent appearance, and the flow mark is suppressed. Can be. As said other resin composition, the said thermoplastic resin etc. are mentioned, for example.

  In addition, scrap generated when performing thermoforming such as extrusion molding and blow molding may be reused by blending with the thermoplastic resin layer, or may be used as a separate recovery layer.

  In the above-described vacuum / pressure forming method, for example, a multilayer sheet is heated and softened, and then formed into a mold shape. As a forming method, use vacuum or compressed air (compressed air) and, if necessary, further form a plug with a mold (straight method, drape method, air slip method, snapback method, plug assist method, etc.) And a press molding method. Various molding conditions such as the molding temperature, the degree of vacuum, the pressure of compressed air, and the molding speed are appropriately set depending on the plug shape, mold shape, raw material film and sheet properties, and the like.

  The molding temperature is not particularly limited as long as the resin is softened to a sufficient degree for molding. For example, when thermoforming a multilayer sheet, the multilayer sheet is not melted by heating, and the metal surface of the heater plate is not heated to such a high temperature that it is transferred to the multilayer sheet. It is desirable that the temperature is not too low. Specifically, the temperature of the multilayer sheet is 50 ° C to 180 ° C, preferably 60 ° C to 160 ° C.

  The container is manufactured by being thermoformed into a three-dimensional shape in which a recess is formed in the plane of the multilayer sheet. The container is suitably formed by the vacuum / pressure forming method described above. The shape of the concave portion is determined in accordance with the shape of the contents. In particular, as the depth of the concave portion is deeper and the shape of the concave portion is not smooth, the normal EVOH laminate is likely to cause uneven thickness, such as a corner portion. Is extremely thin, so the improvement effect of the present invention is great. When the container is formed by molding a multilayer sheet having a total layer thickness of less than about 300 μm, the draw ratio (S) is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably. When the ratio is 0.4 or more, the effect of the present invention is more effectively exhibited. When the container is formed by molding a multilayer sheet having a total layer thickness of about 300 μm or more, the drawing ratio (S) is preferably 0.3 or more, more preferably 0.5 or more, The effect of the present invention is more effectively exhibited when it is preferably 0.8 or more.

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

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

That is, the drawing ratio (S) is obtained by dividing the value of the depth of the deepest part of the container by the value of the diameter of the largest inscribed circle in contact with the shape of the recess (opening) formed in the plane of the multilayer sheet. Value. The diameter of the circle is, for example, the diameter of the concave portion when the shape is a circle, the short diameter when the shape is an ellipse, and the shortest length when the shape is a rectangle. Is the value of the diameter.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples. In addition, each fixed_quantity | quantitative_assay in a present Example was performed using the following method.

[Measurement of moisture content of hydrous EVOH pellets]
The moisture content of the hydrous EVOH pellets was measured using a halogen moisture content analyzer “HR73” manufactured by METTLER TOLEDO under the conditions of a drying temperature of 180 ° C., a drying time of 20 minutes, and a sample amount of about 10 g. The moisture content of the water-containing EVOH shown below is mass% based on the dry mass of EVOH.

[Ethylene content and saponification degree of EVOH (A)]
Using a nuclear magnetic resonance apparatus (“JNM-GX-500 type” manufactured by JEOL Ltd.), it was determined by ¹ H-NMR using DMSO-d ₆ as a measurement solvent.

[Quantification of carboxylic acid and carboxylate ion]
Dry EVOH pellets were ground by freeze grinding. The obtained pulverized EVOH was divided by a sieve having a nominal size of 1 mm (conforming to standard fluid standard JIS Z8801-3). 10 g of EVOH powder and 50 mL of ion exchanged water that passed through the sieve were put into a 100 mL Erlenmeyer flask with a stopper, and a cooling condenser was attached, followed by stirring at 95 ° C. for 10 hours. 2 mL of the obtained solution was diluted with 8 mL of ion exchange water. The amount of the carboxylic acid and the carboxylate ion was calculated by quantifying the amount of the carboxylate ion of this diluted solution according to the following measurement conditions using ion chromatography “ICS-1500” manufactured by Yokogawa Electric Corporation. A calibration curve prepared using monocarboxylic acid or polyvalent carboxylic acid was used for quantification.

(Measurement condition)
Column: “IonPAC ICE-AS1 (9φ × 250 mm, electrical conductivity detector)” from DIONEX

Eluent: 1.0 mmol / L Octanesulfonic acid aqueous solution Measurement temperature: 35 ° C
Eluent flow rate: 1 mL / min.
Analytical volume: 50 μL

[Quantitative determination of metal ions]
0.5 g of dry EVOH pellets were charged into a Teflon (registered trademark) pressure vessel made by Actac, and 5 mL of nitric acid for precision analysis from Wako Pure Chemical Industries, Ltd. was further added. After standing for 30 minutes, the container is covered with a cap lip with a rupture disk, treated at 150 ° C for 10 minutes and then at 180 ° C for 10 minutes with Actac's microwave high-speed decomposition system "Speedwave MWS-2", and dried EVOH The pellet was broken down. When the decomposition of the dry EVOH pellets was not completed, the processing conditions were adjusted as appropriate. The obtained decomposition product was diluted with 10 mL of ion exchange water, and all the liquids were transferred to a 50 mL volumetric flask and the volume was adjusted with ion exchange water to obtain a decomposition product solution.

  By using the ICP emission spectroscopic analyzer “Optima 4300 DV” of PerkinElmer Japan, the obtained decomposition product solution is quantitatively analyzed at each of the following observation wavelengths, so that metal ions, phosphate compounds and boron compounds can be obtained. The amount was quantified. The amount of the phosphoric acid compound was calculated as phosphorus element equivalent mass by quantifying phosphorus element. The boron compound content was calculated as boric acid equivalent mass.

Na: 589.592 nm
K: 766.490 nm
Mg: 285.213 nm
Ca: 317.933 nm
P: 214.914 nm
B: 249.667 nm
Si: 251.611 nm
Al: 396.153 nm
Zr: 343.823 nm
Ce: 413.764 nm
W: 207.912 nm
Mo: 202.031 nm

(5) Determination of conjugated polyene compound Obtained by pulverizing dry resin composition pellets by freeze pulverization and removing coarse particles with a sieve having a nominal size of 0.150 mm (100 mesh) (conforming to JIS standard Z8801-1-3) 10 g of the pulverized product was filled in a Soxhlet extractor and extracted with 100 mL of chloroform for 48 hours. The amount of the conjugated polyene compound was quantitatively analyzed by high performance liquid chromatography to quantify the amount of the conjugated polyene compound. For quantification, a calibration curve prepared using a sample of each conjugated polyene compound was used.

<Synthesis of EVOH (A)>
[Synthesis Example 1]
Polymerization was carried out under the following conditions using a 250 L pressurized reaction tank to synthesize an ethylene-vinyl acetate copolymer.
(Preparation amount)
Vinyl acetate: 83.0kg
Methanol: 17.4kg
2,2′-azobisisobutylnitrile: 66.4 g
(Polymerization conditions)
Polymerization temperature: 60 ° C
Polymerization tank ethylene pressure: 3.9 MPa
Polymerization time: 3.5 hours The polymerization rate of vinyl acetate in the above polymerization was 36%. After adding sorbic acid to the obtained copolymerization reaction liquid, it is supplied to the purge tower, unreacted vinyl acetate is removed from the top of the tower by introducing methanol vapor from the bottom of the tower, and an ethylene-vinyl acetate copolymer is obtained. Of 41% by mass in methanol was obtained. The ethylene content of this ethylene-vinyl acetate copolymer was 32 mol%. This methanol solution of ethylene-vinyl acetate copolymer is charged into a saponification reactor, and caustic soda / methanol solution (80 g / L) is added so as to be 0.4 equivalent to the vinyl ester unit in the copolymer. Further, methanol was added to adjust the copolymer concentration to 20% by mass. This solution was heated to 60 ° C. and reacted for about 4 hours while blowing nitrogen gas into the reactor. The solution was extruded into water from a metal plate having a circular opening, precipitated, and cut to obtain pellets having a diameter of about 3 mm and a length of about 5 mm. The pellets were drained with a centrifuge and then washed with repeated operations of adding a large amount of water and then draining to obtain EVOH (A) pellets. The degree of saponification of the obtained EVOH (A) was 99.95 mol%.
Further, in the same manner as described above, EVOH (A) (degree of saponification: 99.95 mol%) having a predetermined ethylene content shown in Table 1 below was synthesized.

[Synthesis Example 2]
Propanal was polymerized, saponified, pelletized and washed in the same manner as in Synthesis Example 1 except that it was supplied at the time of polymerization so as to contain 0.5 ppm with respect to EVOH (A) to obtain pellets. . The degree of saponification of the obtained EVOH (A) was 99.95 mol%.

<Preparation of resin composition>
[Examples 1 to 12, 15 and Comparative Examples 2 to 6]
20 kg of the pellets obtained in Synthesis Example 1 were added to 180 kg of a mixed solvent of water / methanol = 40/60 (mass ratio) and stirred at 60 ° C. for 6 hours to completely dissolve the pellets. A predetermined amount of propanal and sorbic acid were added to the obtained solution, and the mixture was further stirred for 1 hour to completely dissolve propanal to obtain a resin solution. This resin solution was continuously extruded from a nozzle having a diameter of 4 mm into a coagulation bath of water / methanol = 90/10 (mass ratio) adjusted to 0 ° C. to be solidified into a strand. This strand was introduced into a pelletizer to obtain a porous resin chip. The obtained chip was washed with an acetic acid aqueous solution and ion-exchanged water. The cleaning liquid and the chip were separated and drained, followed by drying at 80 ° C. for 4 hours using a hot air dryer, and further drying at 100 ° C. for 16 hours to obtain propanal-containing EVOH pellets. The content of propanal in the obtained pellet was quantified by the above quantification method. Propanal-containing EVOH pellets were prepared so that the content of propanal was as shown in Table 1 by adjusting the amount of propanal added.

  The above prepared propanal-containing EVOH pellets, polyamide (“Ny1018A (nylon 6)” from Ube Industries), and magnesium acetate tetrahydrate, zinc acetate dihydrate or calcium acetate dihydrate are shown. After mixing and dry blending to the content shown in 1, using a twin-screw extruder (“2D25W”, 25 mmφ from Toyo Seiki Seisakusho, die temperature 250 ° C., screw rotation speed 100 rpm) Then, extrusion pelletization was performed in a nitrogen atmosphere to obtain a target resin composition pellet.

[Examples 13 and 14]
For the pellets obtained in Synthesis Example 1, as saturated aldehyde (D), in place of propanal, butanal was used in Example 13, and hexanal was used in Example 14. The resin composition was prepared in the same manner as in Example 12 to obtain saturated aldehyde-containing EVOH pellets. In addition, content of the saturated aldehyde (D) in the obtained pellet was quantified by the said quantification method, and the saturated aldehyde containing EVOH pellet was prepared so that it might become as as described in Table 1. Furthermore, polyamide (“Ny1018A (nylon 6)” from Ube Industries) and magnesium acetate tetrahydrate were mixed so as to have the contents shown in Table 1, and after dry blending, a twin-screw extruder (Toyo Seiki Seisakusho) Extrusion pelletization was performed in a nitrogen atmosphere under the extrusion conditions of a die temperature of 250 ° C. and a screw rotation speed of 100 rpm using the “2D25W” (25 mmφ) of the company to obtain the desired resin composition pellets.

[Comparative Example 1]
20 kg of the pellet obtained in Synthesis Example 2 was washed with an acetic acid aqueous solution and ion-exchanged water. The cleaning liquid and chips were separated and drained, followed by drying at 80 ° C. for 4 hours using a hot air dryer, and further drying at 100 ° C. for 16 hours to obtain EVOH pellets.

  The above-prepared EVOH pellets, polyamide (“Ny1018A (nylon 6)” from Ube Industries) and magnesium acetate tetrahydrate are mixed so as to have the contents shown in Table 1, and after dry blending, biaxial Using an extruder (“2D25W” manufactured by Toyo Seiki Seisakusho Co., Ltd., 25 mmφ), extrusion pelletization was performed in a nitrogen atmosphere under extrusion conditions of a die temperature of 250 ° C. and a screw rotation speed of 100 rpm, to obtain the desired resin composition pellets. .

<Manufacture of multilayer sheets>
Using the single-screw extruder (“D2020” manufactured by Toyo Seiki Seisakusho, (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight)) A single layer film having a thickness of 20 μm was prepared from the composition pellets. Each extrusion condition at this time is as follows.
Extrusion temperature: 250 ° C
Screw rotation speed: 40rpm
Dice width: 30cm
Take-up roll temperature: 80 ° C
Take-up roll speed: 3.1 m / min

  Single-layer film produced above, commercially available biaxially stretched nylon 6 film (Unitika “Emblem ON”, thickness 15 μm) and commercially available unstretched polypropylene film (Mitsui Chemicals Tosero CP “Tosero CP”) , 60 μm in thickness) each cut into A4 size, apply dry lamination adhesive on both sides of the single layer film, dry laminate so that the outer layer is nylon 6 film and the inner layer is unstretched polypropylene film The obtained laminate film was dried at 80 ° C. for 3 minutes to evaporate the diluted solution, thereby obtaining a transparent multilayer sheet having three layers. As an adhesive for the above-mentioned dry lamination, “Takelac A-385” manufactured by Takeda Pharmaceutical Co., Ltd. is used as a main agent, “Takenet A-50” manufactured by Takeda Pharmaceutical Co., Ltd. is used as a curing agent, and ethyl acetate is used as a diluent. used. The application amount of this adhesive was 4.0 g / m. After lamination, curing was carried out at 40 ° C. for 3 days.

<Evaluation>
The following evaluation was performed about the obtained resin composition and multilayer sheet. The evaluation results are shown in Table 1.

[Quantification of saturated aldehyde (D)]
50 mg 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) 50 mL, acetic acid 11.5 mL and ion-exchanged water 8 mL were added to 200 mg of an aqueous solution of 50 mass% 2,4-dinitrophenylhydrazine (DNPH). A DNPH solution was prepared. 1 g of the measurement pellet was added to 20 mL of this DNPH solution, and stirred at 35 ° C. for 1 hour to dissolve. Acetonitrile was added to this solution to precipitate the resin component and settled, and then the solution obtained by filtration was concentrated to obtain an extracted sample. Saturated aldehyde (D) was quantified by quantitatively analyzing the extracted sample by high performance liquid chromatography under the following conditions. In the determination, a calibration curve prepared by reacting each sample of saturated aldehyde (D) with a DNPH solution was used. The lower limit of detection of saturated aldehyde (D) was 0.01 ppm.
Column: TSKgel ODS-80Ts (Tosoh Corporation)
Mobile phase: water / acetonitrile = 52: 48 (volume ratio)
Detector: PDA (360 nm), TOF-MS

[Odor during molding]
20 g of sample pellets of the resin composition were placed in a 100 mL glass sample tube, the mouth was covered with aluminum foil, and then heated at 220 ° C. for 30 minutes in a hot air dryer. After removing from the dryer and allowing to cool at room temperature for 30 minutes, the sample tube was shaken 2-3 times, and then the lid of the aluminum foil was removed to evaluate the odor. The intensity of the odor of the sample pellet was determined according to the following criteria.
A: Do not feel odor B: Feel weak odor C: Clearly feel odor

[Kog generation suppression]
From each dry resin composition pellet using a single screw extruder (“D2020” manufactured by Toyo Seiki Seisakusho Co., Ltd., D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) A single-layer film having a thickness of 20 μm was produced. Each condition at this time is as follows.
Extrusion temperature: 250 ° C
Screw rotation speed: 40rpm
Dice width: 30cm
Take-up roll temperature: 80 ° C
Take-up roll speed: 3.1 m / min A single-layer film is produced by continuous operation under the above conditions, and after 8 hours from the start of operation, the resin is switched to low density polyethylene (“Novatech LF128” from Nippon Polyethylene Co., Ltd.) for 30 minutes. The film was formed under the same conditions. Thereafter, the die was disassembled to remove the low-density polyethylene, the amount of koge adhering to the surface of the dice channel was measured, and the kogation inhibitory property was evaluated according to the following evaluation criteria.
“A (good)”: less than 0.01 g “B (slightly good)”: 0.01 g or more and less than 1.0 g “C (bad)”: 1.0 g or more

[Coloring suppression]
From each dry resin composition pellet using a single screw extruder (“D2020” manufactured by Toyo Seiki Seisakusho Co., Ltd .; D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) A single-layer film having a thickness of 20 μm was produced. Each condition at this time is as follows.
Extrusion temperature: 250 ° C
Screw rotation speed: 40rpm
Dice width: 30cm
Take-up roll temperature: 80 ° C
Take-up roll speed: 3.1 m / min A single-layer film is produced by continuous operation under the above conditions, and the appearance (coloring) of each film produced 15 hours after the start of the operation is visually evaluated according to the following evaluation criteria. evaluated.

(Evaluation criteria for coloring)
“Good (A)”: Colorless “Slightly good (B)”: Yellowing “Poor (C)”: Extremely yellowing

[Retort resistance of molded products]
A four-side sealed pouch having an inner size of 12 × 12 cm was produced using the multilayer sheet obtained above. The contents were water. This was subjected to a retort treatment for 20 minutes at 120 ° C. using a retort apparatus (high temperature and high pressure cooking sterilization tester (“RCS-40RTGN” manufactured by Nisaka Seisakusho Co., Ltd.). The retort resistance was evaluated after leaving in a room with high temperature and high humidity of 65% RH for 1 day.The retort resistance was “A (good)” when the transparency was ensured, and was mottled and whitened. If it is, it was evaluated as “B (defect)”.

  As is clear from the results in Table 1, the resin compositions and multilayer sheets of the examples are excellent in the suppression of kogation and retort resistance in the molding machine during long-time operation. On the other hand, the type or content of saturated aldehyde (D), the content of carboxylic acid metal salt (C), or the EVOH / PA mass ratio is outside the specified range. It turned out that it is inferior to the odor at the time, kogation suppression, or retort resistance.

<Manufacture of containers>
[Example 16]
Under the following extrusion molding conditions, the resin composition obtained in Example 4, polyolefin (a), polyolefin (a ′), and carboxylic acid-modified polyolefin (b) were charged into separate extruders, and (a) / ( a ′) / (b) / resin composition / (b) / (a ′) / (a) (each layer thickness: 200 μm / 225 μm / 25 μm / 100 μm / 25 μm / 225 μm / 200 μm) A multilayer sheet of 4 types and 7 layers of 000 μm was obtained by a coextrusion sheet forming apparatus.
Each extruder and extrusion conditions Extruder of polyolefin (a): single screw, screw diameter 65 mm, L / D = 22, temperature 200 ° C. to 240 ° C. (polypropylene)
Extruder of the resin composition obtained in Example 4: Uniaxial, screw diameter 40 mm, L / D = 26, temperature 170 ° C. to 210 ° C.
Carboxylic acid-modified polyolefin (b) extruder: uniaxial, screw diameter 40 mm, L / D = 26, temperature 160 ° C. to 220 ° C. (maleic anhydride-modified polypropylene adhesive resin (“ADMER QF-500 from Mitsui Chemicals, Inc.) "))
Polyolefin (a ′) extruder: uniaxial, screw diameter 40 mm, L / D = 22, temperature 160 ° C. to 210 ° C. (polypropylene)
Molding conditions of coextrusion sheet molding equipment Feed block die (width 600mm), temperature 240 ° C

The obtained multilayer sheet was heated for 1.5 seconds with a thermoforming machine (Mulchback “R530”) with a heater plate temperature of 100 ° C., and the sheet temperature was about 85 ° C. (Vertical: 130 mm, horizontal: 110 mm, depth: 50 mm rectangular parallelepiped shape, drawing ratio S = 0.45), molded by blowing compressed air (pressure 5 kgf / cm ² (0.5 MPa)) Obtained. The obtained container was excellent in appearance and was a good molded body free from kogation.

[Example 17]
The multilayer sheet obtained in Example 16 was formed into a cup shape (die shape 70φ × 70 mm, drawing ratio S = 1.0) by setting the temperature of the multilayer sheet to 150 ° C. with a thermoforming machine (Asano Manufacturing Co., Ltd.). Thermoforming (compressed air: 5 kgf / cm ² (0.5 MPa), plug: 45φ × 65 mm, syntax foam, plug temperature: 150 ° C., mold temperature: 70 ° C.) was performed. The obtained cup container was a good molded article having excellent appearance and no melting spots.

<Manufacture of packaging materials>
[Example 18]
The multilayer sheet obtained in Example 16 was subjected to a pantograph biaxial stretching machine, and simultaneous biaxial stretching was performed at 70 ° C. at a stretching ratio of 3 × 3 times. No stretch spots were observed on the stretched multilayer sheet.

[Comparative Example 7]
Under the following extrusion molding conditions, the resin composition obtained in Comparative Example 1, polyolefin (a), polyolefin (a ′), and carboxylic acid-modified polyolefin (b) were charged into separate extruders (a) / (a Total layer thickness 1, having a configuration of ') / (b) / resin composition / (b) / (a') / (a) (each layer thickness: 200 μm / 225 μm / 25 μm / 100 μm / 25 μm / 225 μm / 200 μm) A multilayer sheet of 4 types and 7 layers of 000 μm was obtained by a coextrusion sheet forming apparatus.
Extruder and Extrusion Conditions Polyolefin (a) extruder: uniaxial, screw diameter 65 mm, L / D = 22, temperature 200-240 ° C. (polypropylene)
Extruder for the resin composition obtained in Comparative Example 1: Uniaxial, screw diameter 40 mm, L / D = 26, temperature 170-210 ° C.
Carboxylic acid-modified polyolefin (b) extruder: uniaxial, screw diameter 40 mm, L / D = 26, temperature 160-220 ° C. (Maleic anhydride-modified polypropylene adhesive resin (“ADMER QF-500” from Mitsui Chemicals, Inc.) ))
Polyolefin (a ′) extruder: uniaxial, screw diameter 40 mm, L / D = 22, temperature 160 to 210 ° C. (polypropylene)
Molding conditions of coextrusion sheet molding machine Feed block die (width 600mm), temperature 240 ℃

The obtained multilayer sheet was heated for 1.5 seconds with a thermoforming machine (Mulchback “R530”) with a heater plate temperature of 100 ° C., and the sheet temperature was about 85 ° C. (Vertical: 130 mm, horizontal: 110 mm, depth: 50 mm rectangular parallelepiped shape, drawing ratio S = 0.45), molded by blowing compressed air (pressure 5 kgf / cm ² (0.5 MPa)) Obtained. Koge was observed in the obtained container.

[Comparative Example 8]
The multilayer sheet obtained in Comparative Example 7 was heated to a cup shape (mold shape 70φ × 70 mm, squeezing ratio S = 1.0) with a thermoforming machine (Asano Seisakusho) at a multilayer sheet temperature of 150 ° C. Molding (compressed air: 5 kg / cm ² (0.5 MPa), plug: 45φ × 65 mm, syntax foam, plug temperature: 150 ° C., mold temperature: 70 ° C.) was performed. Melting spots were observed in the obtained cup container.

[Comparative Example 9]
The multilayer sheet obtained in Comparative Example 7 was subjected to a pantograph-type biaxial stretching machine and subjected to simultaneous biaxial stretching at a stretching ratio of 3 × 3 at 70 ° C. Stretch spots were observed on the stretched multilayer sheet.

  The resin composition of the present invention can effectively suppress kogation and odor in the molding machine during long-time operation, and can produce a molded article excellent in appearance, retort resistance, and mechanical strength. . The multilayer sheet of the present invention is excellent in appearance, retort resistance and processing characteristics. The container of the present invention is excellent in appearance and retort resistance. The packaging material of the present invention is excellent in appearance and the occurrence of stretch spots is suppressed. Therefore, the resin composition, the multilayer sheet, the container and the packaging material are suitable for boil sterilization or retort sterilization.

Claims (11)

Containing ethylene-vinyl alcohol copolymer (A), polyamide (B), carboxylic acid metal salt (C) and saturated aldehyde (D) having an ethylene content of 20 mol% to 60 mol%,
The mass ratio (A / B) of the ethylene-vinyl alcohol copolymer (A) to the polyamide (B) is from 60/40 to 95/5,
The content of the carboxylic acid metal salt (C) with respect to the resin content is 1 ppm to 500 ppm in terms of metal element,
The resin composition whose content with respect to the resin content of the said saturated aldehyde (D) is 0.01 ppm or more and 100 ppm or less.   2. The resin composition according to claim 1, wherein the content of the carboxylic acid metal salt (C) with respect to the resin content is 5 ppm or more in terms of a metal element.   The resin composition according to claim 1 or 2, wherein the metal element of the carboxylic acid metal salt (C) is at least one selected from the group consisting of magnesium, calcium and zinc.   The resin composition according to claim 1, wherein the saturated aldehyde (D) has 3 to 8 carbon atoms.   The resin composition according to claim 4, wherein the saturated aldehyde (D) is at least one selected from the group consisting of propanal, butanal and hexanal. A barrier layer formed from the resin composition according to any one of claims 1 to 5,
A multilayer structure comprising a thermoplastic resin layer laminated on at least one surface of the barrier layer.   A multilayer sheet comprising the multilayer structure according to claim 6.   The multilayer sheet according to claim 7, wherein the barrier layer and the thermoplastic resin layer are laminated by a coextrusion molding method.   A container formed by molding the multilayer sheet according to claim 7 or 8 by a vacuum / pressure forming method.   The container according to claim 9, which is for boil sterilization or retort sterilization.   The packaging material formed by shape | molding the multilayer sheet of Claim 7 or Claim 8 with a hot stretch molding method.