JP5008889B2 - Gas barrier stretched film and gas barrier package using the film - Google Patents

Description

  The present invention provides a gas barrier stretched film that is excellent in oxygen gas barrier properties, transparency, etc., and is suitable for packaging foods, medical products, medicines, etc. that do not want to be altered by oxygen, and a gas barrier packaging material using this film and It relates to a package.

Conventionally, gas barrier resin films made of saponified ethylene-vinyl acetate copolymer (EVOH) have been used as packaging materials that are transparent and have high oxygen barrier properties. The barrier property is, for example, about 3 ml / m ² · day · MPa at 23 ° C. and 50% RH in a stretched film having a thickness of 15 μm (0.3 cc / (m ² · day · atm). There was a problem in printability and pinhole resistance, and there was a situation that it could not be used as a base film for packaging materials.

On the other hand, a laminated stretched film in which polyamide resin (nylon) is co-pressed on both sides of EVOH is also known. However, if the thickness of the EVOH layer is increased in order to improve the gas barrier property, the resulting film becomes brittle and the pinhole resistance required for the stretched film is greatly reduced, resulting in a gas barrier property of 5 ml. It was practically difficult to make it less than / m ² · day · MPa (0.5 cc / m ² · day · atm).

  On the other hand, as a film having a relatively high gas barrier property, a film obtained by depositing a metal oxide on a biaxially stretched polyester film (OPET), a biaxially stretched polyamide film (ONY), or the like is known. However, this film is prone to damage to the deposited film due to bending or the like when laminating or printing the heat seal layer, or during use as a packaging material, in which case the oxygen barrier property may be significantly impaired. there were.

  In addition, a method is also known in which an oxygen absorbing material or the like is arranged in a packaging material to collect permeated oxygen and reduce the apparent oxygen permeability. However, in this method, an oxygen absorber such as iron powder is blended into the resin and used as the wall of the packaging material, so that the point having a relatively good oxygen absorption performance was satisfactory. Therefore, the foreign matter detector cannot be used in the packaging field where transparency is required, or the foreign matter detector cannot be used because it reacts with the metallic foreign matter detector.

  In order to solve the above problems, a gas barrier packaging material having a lower oxygen permeability than the gas barrier resin layer alone is proposed by laminating a gas barrier resin layer outside the oxygen absorbing resin layer made of an oxygen absorbing resin. (See Patent Document 1). However, when this gas barrier packaging material is used, there is a problem that the odor generated from the oxygen-absorbing resin is transferred to the contents.

In addition, an oxygen-absorbing container that can maintain an oxygen-absorbing function for 3 months in a container such as a bottle by laminating a gas barrier resin layer on both sides of the oxygen-absorbing resin layer has also been proposed (see Patent Document 2). However, Document 2 is a proposal relating to a container having a large thickness such as a bottle application, and is not related to a gas barrier film designed by optimally combining an oxygen-absorbing resin layer and a gas barrier resin layer. Especially in the flexible packaging field, it is required to maintain gas barrier properties efficiently for as long as possible with the thin film as a whole, and maintain good gas barrier properties for at least half a year as the product life cycle. This is very important.
JP-T-3-503153 Japanese Patent Laid-Open No. 2002-240813

  The present invention has been made to solve the above-mentioned problems of the prior art, and the object of the present invention is to provide a stretched gas barrier film having high oxygen gas barrier properties and excellent strength, and a gas barrier packaging material using this film. And providing a package.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors combined a gas barrier resin layer having a predetermined oxygen barrier performance and an oxygen absorbing resin layer having a predetermined amount of oxygen absorption ability with a polyamide resin layer. It has been found that the stretched film has both high gas barrier properties and excellent strength, and the present invention has been completed.

That is, an object of the present invention is to provide a laminated film having at least four layers of a polyamide-based resin layer, a first gas barrier resin layer, an oxygen-absorbing resin layer, and a second gas barrier resin layer in a biaxial direction orthogonal to 2. It is a film stretched at a magnification of 5 to 4.5 times, the puncture strength is 196 N / mm (20 Kgf / mm) to 500 N / mm and the oxygen permeability at 23 ° C. and 50% RH This is achieved by a stretched gas barrier film characterized in that a state of 1 ml / m ² · day · MPa (0.1 cc / m ² · day · atm) or less can be maintained for at least 60 days.

The stretched gas barrier film of the present invention stretches a laminated film having at least four layers of a polyamide-based resin layer, a first gas barrier resin layer, an oxygen-absorbing resin layer, and a second gas barrier resin layer under predetermined conditions, The puncture strength is 196 N / mm (20 Kgf / mm) to 500 N / mm, and the oxygen permeability at 23 ° C. and 50% RH is 1 ml / m ² · day · MPa (0.1 cc / m ² · day · atm ) Can maintain the following conditions for at least 60 days. Therefore, according to the present invention, it is possible to provide a stretched gas barrier film that maintains high oxygen barrier properties over a long period of time and has high practical strength.

  The present invention is particularly effective when the gas barrier resin is a saponified ethylene-vinyl acetate copolymer, the oxygen-absorbing resin is a composition containing a polyamide-based resin as a main component and an oxidizable resin and a transition metal-based catalyst. Can exhibit excellent gas barrier performance.

  In the present invention, when a packaging material or a package is produced using the above stretched gas barrier film, excellent oxygen barrier properties and excellent oxygen absorption ability can be stably maintained for a long period of time, and particularly high gas barrier performance and strength can be achieved. A soft packaging material and a soft packaging body can be provided.

Hereinafter, the stretched gas barrier film of the present invention, and the packaging material and package using the film will be described in detail.
In the present specification, “the B layer is laminated on the inside of the A layer” means that when the package is produced using the stretched gas barrier film of the present invention, the B is closer to the contents than the A layer. It means that the layer is arranged, and “the B layer is laminated outside the A layer” means that the B layer is arranged at a position closer to the outside air (in the air) than the A layer. Further, in this specification, “the B layer is laminated on the A layer” means that the B layer is mainly disposed directly on the A layer, but the C layer is further interposed between the A layer and the B layer. Means that it is possible.

[Layer structure]
First, the layer structure of the gas barrier film of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view (No. 1) of a preferred gas barrier stretched film of the present invention, and FIG. 2 is a cross-sectional view (No. 2) of a preferred gas barrier stretched film of the present invention. Here, reference numeral 1 is a stretched gas barrier film of the present invention, reference numeral 2 is a polyamide resin layer, reference numeral 3 is a first gas barrier resin layer, reference numeral 4 is an oxygen-absorbing resin layer, reference numeral 5 is a second gas barrier resin layer, Reference numeral 6 denotes a polyamide-based resin layer.

  As shown in FIG. 1, the gas barrier film 1 of the present invention comprises at least four layers of a polyamide resin layer 2, a first gas barrier resin layer 3, an oxygen absorbing resin layer 4, and a second gas barrier resin layer 5. It is a laminated stretched film. When used as a packaging container or packaging bag, a heat-sealable resin layer can be further laminated and laminated.

  FIG. 2 shows a stretched gas barrier film in which a polyamide resin layer 6 is further arranged inside the second gas barrier resin layer 5. By sandwiching the gas barrier resin layers 3 and 5 between the polyamide resin layers 2 and 6 from both sides, the gas barrier performance can be further improved, and a stretched film having high strength without curling can be provided.

  Although not shown in FIGS. 1 and 2, an adhesive resin layer can be interposed between the respective layers for the purpose of improving the interlayer adhesive strength. However, between the polyamide resin layers, or between the polyamide resin layer and the saponified ethylene-vinyl acetate copolymer layer, the adhesiveness of both resin layers is relatively high, so that no adhesive resin layer is interposed. Both layers can be laminated.

The stretched gas barrier film of the present invention has the above layer structure, but the thickness of the entire gas barrier film is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, 40 μm or less, preferably 35 μm or less, Preferably it is 30 μm or less. If the thickness of the whole film is 10 μm or more, oxygen gas barrier properties, bending pinhole properties, and abrasion resistance can be obtained, and a satisfactory film for packaging applications can be obtained. Moreover, if the thickness of the whole film is 40 micrometers or less, since a film does not become hard too much and it can be made thin as the whole film even if it bonds a heat-sealable resin layer, it is suitable for a flexible packaging use.
In addition, the thickness of each layer which comprises the gas barrier stretched film of this invention is mentioned later.

Although the typical layer structure of the gas barrier stretched film of this invention is illustrated below, it is not limited to these illustrated things. Further, an adhesive layer may be provided between the layers.
(1) Gas barrier resin layer / oxygen absorbing resin layer / gas barrier resin layer / polyamide resin layer (2) First gas barrier resin layer / oxygen absorbing resin layer / polyamide resin layer / second gas barrier resin layer (3) Polyamide resin layer / first gas barrier resin layer / oxygen absorbing resin layer / second gas barrier resin layer (4) first polyamide resin layer / first gas barrier resin layer / oxygen absorbing resin layer / Second gas barrier resin layer / second polyamide resin layer (5) First polyamide resin layer / first gas barrier resin layer / oxygen absorbing resin layer / second polyamide resin layer / second gas barrier resin layer ( 6) First gas barrier resin / first polyamide resin layer / oxygen absorbing resin layer / second polyamide resin layer / second gas barrier resin layer,
(7) First polyamide resin layer / first gas barrier resin layer / first oxygen absorbing resin layer / second oxygen absorbing resin layer / second gas barrier resin layer / second polyamide resin layer,

[Oxygen-absorbing resin layer]
In the stretched gas barrier film of the present invention, the oxygen-absorbing resin used in the oxygen-absorbing resin layer is 1 ml / m ² · at 23 ° C. and 50% RH when used in combination with two types of gas barrier resin layers. It is not particularly limited as long as it can sustain an oxygen permeability of less than day · MPa or less for at least 60 days, but a resin composition containing an oxidizable resin (S) and a transition metal catalyst (M) is preferably used. It is done.

  The oxidizable resin (S) is a resin that is oxidized by oxygen in the air by the action of the transition metal catalyst (M). Specifically, (i) a resin containing a carbon side chain, (ii) xylylene Group-containing polyamide resin, (iii) an ethylenically unsaturated group-containing polymer, (iv) a polyether-containing polymer, and the like. The oxidizable resin (S) is a general thermoplastic resin, for example, a polyamide resin, a polyester resin, or a polyolefin resin as a main component (referred to as a base resin), mixed and dispersed together with a transition metal catalyst to absorb oxygen. It is also preferable to use as a functional resin.

  Oxygen absorption in the composition containing the oxidizable resin (S) and the transition metal catalyst (M) is performed via oxidation of the oxidizable resin (S). This oxidation involves the generation of radicals by the extraction of hydrogen atoms from activated carbon atoms by transition metal catalysts (M), the generation of peroxy radicals by the addition of oxygen molecules to the radicals, the removal of hydrogen atoms by peroxy radicals. The theory that it is performed after each reaction is prominent. Since the resin or polymer of said (i)-(iv) has such an activated carbon atom, it can be used as oxidizable resin (S).

  The resin (i) having a carbon side chain is derived from (i) a modified or unmodified olefin resin, (b) a branched dicarboxylic acid, aliphatic diol, aliphatic oxycarboxylic acid, or lactone. Branched chain-containing thermoplastic polyesters, in particular aliphatic polyesters, (c) branched chain-containing thermoplastic polyamides derived from branched chain aliphatic dicarboxylic acids, aliphatic diamines, aliphatic aminocarboxylic acids, or lactams, in particular fats Group polyamide and the like.

  Examples of the xylylene group-containing polyamide resin (ii) include a xylylene group-containing polyamide resin, particularly a polyamide derived from a diamine component mainly composed of xylylenediamine and a dicarboxylic acid component. It is known that the xylylene group-containing polyamide resin (ii) has oxidizing properties in combination with the transition metal catalyst (M). That is, radicals are generated by the extraction of hydrogen atoms from the methylene chain (especially the methylene chain adjacent to the arylene group) of the xylylene group-containing polyamide resin by the transition metal catalyst (M), and oxidation proceeds by the same reaction mechanism as described above. To do.

  Examples of xylylene group-containing polyamide resins include polymetaxylylene adipamide, polymetaxylylene sebacamide, polymetaxylylene veramide, polyparaxylylene pimeramide, polymetaxylylene azelamide and other homopolymers, And metaxylylene / paraxylylene adipamide copolymer, metaxylylene / paraxylylene pimeramide copolymer, metaxylylene / paraxylylene sebacamide copolymer, metaxylylene / paraxylylene azelamide copolymer, etc. Polymers, or homopolymers or copolymer components thereof, aliphatic diamines such as hexamethylene diamine, alicyclic diamines such as piperazine, aromatic diamines such as para-bis (2aminoethyl) benzene, terephthalic acid Aromatic dicarboxylic acids such as ε-caprolactam Tam, 7-amino such ω- amino acids heptanoic acid, para - copolymers thereof obtained by copolymerizing such aromatic amino acids of the amino methyl benzoate. Of these, a polyamide obtained from a diamine component mainly composed of m-xylylenediamine and / or p-xylylenediamine and an aliphatic dicarboxylic acid and / or an aromatic dicarboxylic acid is preferable. These xylylene group-containing polyamide resins are preferred from the standpoint of oxygen absorption because radical generation and oxygen absorption (peroxide generation) occur efficiently in the adjacent methylene chain portion of the benzene ring.

  As the ethylenically unsaturated group-containing polymer (iii), for example, a polymer derived from polyene is preferably used as the oxidizing polymer. As the polyene, a resin containing a unit derived from an unsaturated hydrocarbon having 4 to 20 carbon atoms, a linear or cyclic conjugated or non-conjugated diene is preferably used. Examples of these monomers include conjugated dienes such as butadiene and isoprene; 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4 -Chain non-conjugated dienes such as hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene; methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-methylene-2- Cyclic non-conjugated dienes such as norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, dicyclopentadiene; 2,3-diisopropylidene -5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propeni Triene such as 2,2-norbornadiene, such as chloroprene, and the like.

  The above polyenes can be used alone, in combination of two or more, or in combination with other monomers to form a homopolymer, a random copolymer, or a block copolymer. Monomers used in combination with polyene include α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyl-1 -Decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, and other monomers such as styrene, vinyl toluene, acrylonitrile, methacrylonitrile, vinyl acetate, methyl methacrylate, ethyl acrylate Is possible.

  Specific examples of the polyene polymer include polybutadiene (BR), polyisoprene (IR), butyl rubber (IIB), natural rubber, nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), chloroprene rubber ( CR), ethylene-propylene-diene rubber (EPDM) and the like, but are not limited to these examples.

  The carbon atom adjacent to the carbon-carbon double bond in the polyene polymer has activity, and the hydrogen atom can be easily extracted. The carbon-carbon double bond in the polymer is not particularly limited, and may be present in the main chain in the form of a vinylene group or may be present in the side chain in the form of a vinyl group.

  As the polyether-containing polymer (iv), for example, polypropylene oxide, polybutylene oxide (2, 3 or 1, 2) and polystyrene oxide are preferably used.

  The oxygen-absorbing resin can be composed of only the oxidizable resin (S) and the transition metal catalyst (M), but is preferably mixed and dispersed with other thermoplastic resins as main components. . By adjusting the mixing / dispersing amount, the oxygen absorption capacity as the oxygen-absorbing resin can be adjusted, and the influence of deterioration of physical properties after oxygen absorption can be reduced. When mixed and dispersed in other thermoplastic resins, the oxidizable resin (S) is present in a proportion of 1 to 20% by mass, preferably 3 to 10% by mass, based on the total amount of the oxygen-absorbing resin. It is preferable to adjust as follows. In that case, in order to make it easy to disperse the oxidizable resin (S) in the thermoplastic resin, it is preferable to introduce an epoxy group or an anhydrous functional group into the oxidizable resin.

  The introduction of an epoxy group or an anhydrous functional group into the oxidizable resin (S) will be described by taking acid modification of a polyene polymer as an example. The acid-modified polyene polymer is produced by using a polyene polymer having a carbon-carbon double bond as a base polymer and graft copolymerizing an unsaturated carboxylic acid or a derivative thereof with the base polymer by a known means. However, it can also be produced by random copolymerization of the aforementioned polyene with an unsaturated carboxylic acid or derivative thereof.

  The acid-modified polyene polymer particularly suitable for the purpose of the present invention preferably contains 0.01 to 10 mol% of an unsaturated carboxylic acid or a derivative thereof in the polymer. When the content of the unsaturated carboxylic acid or derivative thereof is in the above range, the acid-modified polyene polymer is favorably dispersed in another resin (matrix resin) and oxygen is smoothly absorbed. Further, a hydroxyl group-modified polyene polymer having a hydroxyl group at the terminal can also be used favorably.

  Specific examples of functional oxidizable polydienes as suitable oxygen scavengers are epoxy functionalized polybutadiene (1,4 and / or 1,2), maleic anhydride grafted or copolymerized polybutadiene (1,4 and And / or 1,2), epoxy functionalized polyisoprene, and maleic anhydride grafted or copolymerized polyisoprene, amine, epoxy or anhydrous functional polypropylene oxide, polybutylene oxide (2,3 or 1,2) and For example, polystyrene oxide.

  As the other thermoplastic resin which is the main component of the oxygen-absorbing resin, a general thermoplastic resin usually used for a film is used. In particular, a polyamide-based resin is preferable because it easily improves the strength of the film.

  Suitable polyamide-based resins include polyamide homopolymers or copolymers. The polyamide homopolymer or copolymer is selected from aliphatic polyamides and aliphatic / aromatic polyamides having a molecular weight of from about 10,000 to about 100,000. The polyamide homopolymer or copolymer can be produced by a known method. In this case, useful dibasic acids are dicarboxylic acids represented by the following general formula (1) and diamines represented by the general formula (2). Including.

                HOOC-Z-COOH General formula (1)

  Z in the general formula (1) represents a divalent aliphatic radical containing at least two carbon atoms. For example, adipic acid, sebacic acid, octadecanedioic acid, pimelic acid, suberic acid, azelaic acid, dodecane A diacid, glutaric acid, etc. are mentioned. The dicarboxylic acid may be an aliphatic acid or an aromatic acid such as isophthalic acid and terephthalic acid.

H ₂ N (CH ₂ ) _n NH ₂ general formula (2)

  In general formula (2), n is an integer of 1-16, for example, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, hexadecamethylene. Diamines, aromatic diamines such as p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenylmethane, alkylated diamines such as 2,2-dimethylpenta And compounds such as methylene diamine, 2,2,4-trimethylhexamethylene diamine, and 2,4,4-trimethylpentamethylene diamine, and alicyclic diamines such as diaminodicyclohexylmethane, and other compounds. It is. Examples of other useful diamines include heptamethylene diamine and nonamethylene diamine.

  Useful aliphatic polyamide homopolymers include poly (4-aminobutyric acid) (nylon 4), poly (6-aminohexanoic acid) (also known as nylon 6, poly (caprolactam)), poly (7-aminoheptane) Acid) (nylon 7), poly (8-aminooctanoic acid) (nylon 8), poly (9-aminononanoic acid) (nylon 9), poly (10-aminodecanoic acid) (nylon 10), poly (11-aminoundecane) Acid) (nylon 11), poly (12-aminododecanoic acid) (nylon 12), poly (hexamethylene adipamide) (nylon 6,6), poly (hexamethylene sebacamide) (nylon 6,10), Poly (heptamethylene pimelamide) (nylon 7,7), poly (octamethylenesuberamide) (nylon 8,8), poly (hexamethy Poly (nonamethylene azeramide) (nylon 9,9), poly (decamethylene azeramide) (nylon 10,9), poly (tetramethylene adipamide) (nylon 4,6) ), Caprolactam / hexamethylene adipamide copolymer (nylon 6,6 / 6), hexamethylene adipamide / caprolactam copolymer (nylon 6 / 6,6), trimethylene adipamide / hexamethylene azelaamide copolymer (nylon) Trimethyl 6,2 / 6,2), hexamethylene adipamide-hexamethylene-azeraiamide caprolactam copolymer (nylon 6,6 / 6,9 / 6), poly (tetramethylenediamine-co-oxalic acid) (nylon) 4,2), polyamide of n-dodecanedioic acid and hexamethylenediamine Nylon 6,12), the polyamide of dodecamethylenediamine and n- dodecanedioic acid (nylon 12,12), as well as such blends and copolymers, and other polyamides which are not specifically mentioned herein.

  Of the polyamide-based resins described above, suitable polyamides are polycaprolactam (commonly referred to as nylon 6), polyhexamethylene adipamide (commonly referred to as nylon 6,6), and mixtures thereof. It is. Of these, polycaprolactam is most preferred.

  Examples of aliphatic / aromatic polyamides include, for example, poly (2,2,2-trimethylhexamethylene terephthalamide), poly (m-xylene adipamide) (MXD6), poly (p-xylene adipamide) , Poly (hexamethylene terephthalamide) (nylon 6, T), poly (hexamethylene isophthalamide) (nylon 6, I), poly (dodecamethylene terephthalamide), polyamide 6T / 6I, poly (tetramethylenediamine-co- Isophthalic acid) (nylon 4, I), polyamide 6 / MXDT / I, polyamide MXDI, hexamethylene adipamide / hexamethylene-isophthalamide (nylon 6, 6 / 6I), hexamethylene adipamide / hexamethylene terephthalamide (Nylon 6,6 / 6T), and special mention in this specification Other things that are not. Blends of two or more aliphatic / aromatic polyamides and / or aliphatic polyamides can also be used. Aliphatic / aromatic polyamides can be produced by known production techniques or are commercially available.

  The polyamide-based resin may further include nanometer-scale dispersed clay for the purpose of improving the gas barrier property of the oxygen-absorbing resin. Suitable clays are natural or synthetic layered silicates such as montmorillonite, hectorite, vermiculite, bidelite, saponite, nontronite or synthetic fluoromica, which have been cation exchanged with a suitable organic ammonium salt. Suitable clays are montmorillonite and hectorite. Clay has an average thickness in the range of 1 nm to 100 nm, an average length and an average width in the range of 50 nm to 500 nm, and is 10% by mass or less, preferably 2% by mass to 8% by mass in the polyamide-based resin. More preferably, it is present in an amount ranging from 3% by mass to 6% by mass.

  Next, the transition metal catalyst (M) used in the film of the present invention will be described. The transition metal catalyst (M) serves as a catalyst for the oxidation reaction of the oxidizable resin (S), and an organic acid salt or an organic complex salt of a transition metal is preferably used. The transition metal catalyst used is preferably a group VIII metal component of the periodic table such as iron, cobalt, nickel, etc., but also a group I metal such as copper, silver, etc .: a group IV metal such as tin, titanium, zirconium, etc. And V group of vanadium, group VI such as chromium, and group VII metal components such as manganese. Among these transition metal catalysts, the cobalt component is particularly suitable because of its high oxygen absorption rate.

  The transition metal catalyst (M) is generally used in the form of the above-described transition metal low-valent inorganic acid salt, organic acid salt, or complex salt. Examples of inorganic acid salts include halides such as chlorides, sulfur oxyacid salts such as sulfates, nitrogen oxyacid salts such as nitrates, phosphorus oxyacid salts such as phosphates, and silicates. On the other hand, examples of the organic acid salt include a carboxylate, a sulfonate, and a phosphonate. The carboxylate is suitable for the purpose of the present invention, and specific examples thereof include acetic acid, propionic acid, isopropylate. On acid, butanoic acid, isobutanoic acid, pentanoic acid, isopentanoic acid, hexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, neodecane Acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, lindelic acid, tuzuic acid, petroceric acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, formic acid, oxalic acid, Examples include transition metal salts such as sulfamic acid and naphthenic acid. On the other hand, as the transition metal complex, a complex with β-diketone or β-keto acid ester is used, and examples of β-diketone or β-keto acid ester include acetylacetone, ethyl acetoacetate, 1,3-cyclohexane. Sadione, methylenebis-1,3-cyclohexadione, 2-benzyl-1,3-cyclohexadione, acetyltetralone, palmitoyltetralone, stearoyltetralone, benzoyltetralone, 2-acetylcyclohexanone, 2-benzoylcyclohexanone 2-acetyl-1,3-cyclohexanedione, benzoyl-p-chlorobenzoylmethane, bis (4-methylbenzoyl) methane, bis (2-hydroxybenzoyl) methane, benzoylacetone, tribenzoylmethane, diacetylbenzoylmethane Stearoylbenzoylmethane, palmitoylbenzoylmethane, lauroylbenzoylmethane, dibenzoylmethane, bis (4-chlorobenzoyl) methane, bis (methylene-3,4-dioxybenzoyl) methane, benzoylacetylphenylmethane, stearoyl (4-methoxybenzoyl) ) Methane, butanoylacetone, distearoylmethane, acetylacetone, stearoylacetone, bis (cyclohexanoyl) -methane, dipivaloylmethane, and the like can be used.

  In the oxygen-absorbing resin, the transition metal catalyst (B) is desirably contained in a proportion of 10 ppm or more, preferably 50 ppm or more, 200 ppm or less, preferably 100 ppm or less, relative to the thermoplastic resin contained as the main component. . Various methods can be used as a method of blending the transition metal catalyst (B) with the thermoplastic tree. For example, the transition metal catalyst (B) can be simply dry blended with the thermoplastic resin, but since the transition metal catalyst (B) is a small amount compared to the thermoplastic resin, in order to perform the blending homogeneously, The transition metal catalyst (B) is dissolved in an organic solvent, this solution and a powder or granular resin are mixed, and if necessary, this mixture is dried under an inert atmosphere.

  Solvents for dissolving the transition metal catalyst (M) include alcohol solvents such as methanol, ethanol and butanol, ether solvents such as dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran and dioxane, and ketone solvents such as methyl ethyl ketone and cyclohexanone. A hydrocarbon solvent such as a solvent, n-hexane, and cyclohexane can be used. The concentration of the transition metal catalyst (M) is preferably 5 to 90% by mass with respect to the solvent.

  The mixture of the oxidizing polymer component and the transition metal catalyst (M), and subsequent storage is preferably performed in a non-oxidizing atmosphere so that oxidation in the previous stage of the oxygen-absorbing resin does not occur. For this purpose, mixing or drying under reduced pressure or in a nitrogen stream is preferred. This mixing and drying can be performed at a stage prior to the molding process using an extruder or an injection machine with a vent type or a dryer. Also, a masterbatch of an oxidizing polymer component containing a transition metal catalyst at a relatively high concentration is prepared, and this masterbatch is dry blended with an unblended polymer to prepare the oxygen-absorbing resin of the present invention. You can also

  The oxygen-absorbing resin used in the present invention may optionally contain one or more conventional additives, the use of which is well known to those skilled in the art. The use of such additives is desirable for improving the processing of the composition and for improving the products and products formed from the composition. Examples of such additives are organic or organic, including oxidation and heat stabilizers, lubricants, mold release agents, flame retardants, oxidation inhibitors, dyes, pigments and other colorants, UV stabilizers, particles and fiber fillers. Inorganic fillers, reinforcing agents, nucleating agents, plasticizers, and other conventional additives known in the art. Such an additive can be used up to 10% by mass of the total amount of the oxygen-absorbing resin.

  The thickness of the oxygen-absorbing resin layer can be appropriately determined so as to obtain a desired oxygen-absorbing capacity, but is preferably 1 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, preferably 15 μm or less, preferably Is 10 μm or less, more preferably 8 μm or less. If the thickness of the oxygen-absorbing resin layer is 1 μm or more, high oxygen gas barrier properties can be maintained for a long time, and if it is 10 μm or less, sufficient oxygen-absorbing property can be maintained, and this is economically preferable.

[Gas barrier resin layer]
Examples of the gas barrier resin used in the first gas barrier resin layer and the second gas barrier resin layer of the present invention include a thermoplastic resin having oxygen barrier performance and thermoforming. The most suitable example of the gas barrier resin is saponified ethylene-vinyl acetate copolymer (EVOH).

The ethylene content in the saponified ethylene-vinyl acetate copolymer is not particularly limited, but is 23 mol% or more, preferably 27 mol% or more from the viewpoint of film formation stability, and from the viewpoint of gas barrier properties. It is desirable that the amount be 38 mol% or less, preferably 32 mol% or less.
Further, EVOH has a saponification degree of 96% or more, preferably 99 mol% or more. By maintaining the ethylene content and saponification degree in the saponified ethylene-vinyl acetate copolymer within the above ranges, the oxygen barrier property of the gas barrier film of the present invention can be maintained, and the coextrusion property and the strength of the film can be maintained. And can be improved.

The oxygen permeability of the first gas barrier resin layer is preferably 30 ml / m ² · day · atm (3 cc / m ² · day · atm) or less at 23 ° C. and 50% RH, and is 20 ml / m. ² · day · atm ( ² cc / m ² · day · atm) or less is more preferable, and 10 ml / m ² · day · atm (1 cc / m ² · day · atm) or less is most preferable. If the oxygen barrier performance of the first gas barrier resin layer is 30 ml / m ² · day · atm (3 cc / m ² · day · atm) or less, the first gas barrier resin is combined with the oxygen-absorbing resin layer. The thickness of the layer can be kept within a predetermined range, and the oxygen barrier performance of the entire film can be maintained at 1 ml / m ² · day · atm or less. The oxygen permeability of the second gas barrier resin layer is preferably 100 ml / m ² · day · MPa (10 cc / m ² · day · atm) or less under the condition of 23 ° C. and 50% RH, and 80 ml / m more preferably ^{m 2 · day · MPa (8cc} / m 2 · day · atm) or less, and most preferably not more than ^{50ml / m 2 · day · MPa} (5cc / m 2 · day · atm). If the oxygen barrier performance of the second gas barrier resin layer is 100 ml / m ² · day · MPa (10 cc / m ² · day · atm) or less, the oxygen to the oxygen-absorbing resin layer (a) until the contents are sealed Absorption can be suppressed, and long-term storage becomes easy.

  The thickness of the gas barrier resin layer is 1 μm or more, preferably 2 μm or more, and 10 μm or less, preferably 7 μm or less, more preferably 5 μm or less, for each of the first and second gas barrier resin layers. If the thickness of the gas barrier resin layer is within the above range, the oxygen barrier property can be maintained for a long period of time, the packaging material becomes hard and the occurrence of pinholes due to bending is suppressed, and the packaging cost is further reduced. High can be suppressed. When it is desired to reduce the thickness of each of the first and second gas barrier resin layers, EVOH having as little ethylene content as possible is preferably used as the gas barrier resin.

[Polyamide resin layer]
In the present invention, an aliphatic polyamide resin is mainly used as the polyamide resin constituting the polyamide resin layer. The aliphatic polyamide resin may be further mixed with a semi-aromatic polyamide resin. Examples of the aliphatic polyamide resin in the present invention include a ring-opening polymer of cyclic lactam, a polycondensate of aminocarboxylic acid, a polycondensate of dicarboxylic acid and diamine, and the like. Among them, a homopolymer of ε-caprolactam called nylon-6 and polyhexamethylene adipamide called nylon-66 are preferable because they can be obtained at low cost and can smoothly perform the stretching operation. In addition, examples of the semi-aromatic polyamide resin in the present invention include poly-m-xylylene adipamide called MXD6 and amorphous polyamide.

  Moreover, in this invention, a bending-resistant pinhole property can be improved further by adding a bending-resistant pinhole property improving material to a polyamide-type resin layer.

  Examples of the bending-resistant pinhole improving material that can be used include polyolefins, polyamide elastomers, and polyester elastomers. Polyamide elastomers belong to polyamide-based block copolymers such as polyether amide and polyether ester amide. Examples of amide components include nylon 6, nylon 6, 6, nylon 12, and the like. Examples thereof include oxytetramethylene glycol, polyoxyethylene glycol, polyoxy-1,2-propylene glycol, and the like, and a copolymer having polytetramethylene glycol and polylauryl lactam (nylon 12) as main components is preferable. Further, it may contain a small amount of dicarboxylic acid such as dodecanedicarboxylic acid, adipic acid, terephthalic acid as an optional component.

  Examples of the polyester elastomer include a polyether ester elastomer that combines polybutylene terephthalate and polytetramethylene glycol, and a polyester ester elastomer that combines polybutylene terephthalate and polycaprolactone.

Polyolefins refer to those containing 50 mass% or more of polyethylene units and polypropylene units in the main chain, and include those graft-modified with maleic anhydride or the like. Examples of structural units other than polyethylene units and polypropylene units include vinyl acetate, or partially saponified products thereof, acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, or partial metal neutralized products (ionomers) thereof. 1-alkenes such as butene, alkadienes, styrene and the like. A plurality of these structural units may be included.
The bending-resistant pinhole improving material may be used alone or in combination of two or more.

  The total thickness of the polyamide resin layer in the stretched gas barrier film of the present invention is appropriately determined in view of the strength and pinhole resistance of the stretched film obtained. In particular, in the field of soft packaging materials such as various pouch packaging materials, it is preferable to occupy 40% or more of the total thickness of the film, specifically 4 to 25 μm, more preferably 6 to 15 μm.

  In the present invention, the polyamide-based resin layer may be a single layer or two or more layers, and the layer structure is appropriately determined in consideration of film strength and pinhole resistance.

[Relationship between oxygen-absorbing capacity of oxygen-absorbing resin layer, oxygen permeability of first gas barrier resin layer, and polyamide-based resin layer]
In the gas barrier film of the present invention, the oxygen-absorbing resin layer has an oxygen absorption capacity higher than the oxygen permeation amount per unit area when the first gas barrier resin is stored at 23 ° C. and 50% RH for 60 days. is necessary.

The oxygen barrier performance of the gas barrier resin layer varies depending on the type of resin constituting the gas barrier resin layer, the thickness of the layer, and the like. The oxygen barrier performance of the gas barrier resin layer is calculated by measuring the oxygen permeability (Y) (ml / m ² · day · MPa) in the film after preparing a film with a predetermined thickness using the gas barrier resin. it can. Even if such a film cannot be produced, it is possible to estimate the oxygen transmission rate (Y ′) of a film having a predetermined thickness from the catalog value of the gas barrier resin. The oxygen permeability can be measured by a general method, for example, an OXY-TRAN oxygen permeability measuring device manufactured by Modern Control. The measurement conditions are generally 23 ° C. and 50% RH.

  The first gas barrier resin layer and the second gas barrier resin layer need to be on both sides of the oxygen-absorbing resin layer. When there is no gas barrier resin layer or only one side (that is, only the first gas barrier resin layer or the second gas barrier resin layer), the oxygen-absorbing resin layer is kept at a high temperature of Tg or higher during film stretching and heat setting. In the meantime, it absorbs oxygen and saturates its oxygen absorption capacity. Unless this step can be performed under oxygen-free conditions, a gas barrier resin layer is necessary on both sides of the oxygen-absorbing resin layer. The first gas barrier resin layer and the second gas barrier resin layer may be the same material or different materials, but considering the curl resistance and productivity, they are substantially the same material and have substantially the same thickness. It is preferable.

Generally, the oxygen absorption capacity of the oxygen-absorbing resin layer is determined by measuring the oxygen absorption capacity (ml / g) of the oxygen-absorbing resin itself and converting it per unit area of a predetermined thickness. The oxygen-absorbing capacity of the oxygen-absorbing resin is such that a film made of an oxygen-absorbing resin having a predetermined thickness is produced, and the amount of oxygen absorbed per unit weight is calculated from the amount of oxygen absorbed until saturation (Xml / g). The oxygen absorption capacity per unit area can be calculated from the thickness (Aμm) of the oxygen-absorbing resin layer and the density (dg / cm ³ ) of the oxygen-absorbing resin according to the following formula 1.
X × 10000 × A / 10000 × d = X × A × d (ml / m ² ) (Equation 1)
Where X is the oxygen absorption capacity (ml / g) of the oxygen-absorbing resin, A is the thickness (μm) of the oxygen-absorbing resin layer (a), and d is the density (g / cm ³ ) of the oxygen-absorbing resin. .

On the other hand, as described above, the oxygen-absorbing resin layer is obtained from the amount of oxygen permeating through the first gas barrier resin layer when the first gas barrier resin layer is stored in a standard state (23 ° C., 50% RH) for 60 days. It is necessary to have a high oxygen absorption capacity. The amount of oxygen permeating through the first gas barrier resin layer in the standard state (23 ° C., 50% RH) for 60 days is expressed by the following formula 2 using the oxygen permeability (Y) of the film having the predetermined thickness. Can be calculated.
(Y / 10) x 0.21 x 60 (ml / m ² ) (Equation 2)

That is, the present invention can maintain high oxygen barrier performance for 60 days or more by combining an oxygen-absorbing resin that satisfies the following formula 3 with the first gas barrier resin layer and the second gas barrier resin layer. A stretched gas barrier film can be provided.
X × A × d> (Y / 10) × 0.21 × 60 (Equation 3)

  The stretched gas barrier film of the present invention is obtained by laminating a polyamide resin layer on a laminated film composed of a first gas barrier resin layer / oxygen absorbing resin layer / second gas barrier resin layer. Thereby, the stretched gas barrier film of the present invention can improve the strength of the film. Particularly in the flexible packaging field where pinhole resistance is required, the thickness of the polyamide-based resin layer is preferably 40% or more, more preferably 50% or more of the total film thickness. Furthermore, by laminating a polyamide resin layer on both outer layers of the laminated film, the wear resistance and the like can be improved, and a preferred stretched film can be obtained. Particularly preferred is a polyamide-based resin layer / first gas barrier resin layer / oxygen-absorbing resin layer / second gas barrier resin layer / polyamide resin layer, which maintains stable gas barrier performance and film strength without curling. can do.

  The stretched gas barrier film of the present invention can be subjected to further processing by laminating a sealant layer on the laminated film. By providing a coating layer of vinylidene chloride resin, polyvinyl alcohol resin, ethylene-vinyl acetate copolymer saponified resin, etc. on this film, the gas barrier property was further improved, and the flex pinhole resistance was excellent. A film is obtained. Moreover, the laminated body obtained by laminating | stacking with a various single layer or laminated | multilayer film by the dry lamination method, the wet lamination method, the extrusion lamination method, etc. becomes the thing excellent in the bending pinhole property.

[Puncture strength]
The puncture strength of the stretched gas barrier film of the present invention is 196 N / mm or more, preferably 200 N / mm or more, more preferably 250 N / mm or more, 500 N / mm or less, preferably 480 N / mm or less, more preferably 450 N. / Mm or less. When the puncture strength is 196 N / mm or less, pinholes are likely to occur in the contents and external protrusions when used as a packaging material. As a result, it is not preferable because a film cannot be stably obtained. The piercing strength is the maximum when the specimen is conditioned for 24 hours under conditions of 23 ° C. and 50% RH, and a needle with a tip diameter of 0.5 mm penetrates the specimen at a speed of 50 mm / min under the same conditions. It can be calculated from a numerical value obtained by measuring the load and dividing by the thickness (mm) of the test piece.

<The manufacturing method of the gas-barrier film of this invention>
The stretched gas barrier film of the present invention can be produced by a known general method. For example, using a gas barrier resin, oxygen-absorbing resin, polyamide resin or the like as a raw material, a laminated film that is substantially amorphous and not oriented (hereinafter referred to as “laminated unstretched film”) is usually produced by a coextrusion method. It is good to manufacture. The production of this laminated unstretched film is, for example, by melting the above raw materials with 3 to 5 extruders, extruding from a flat die or an annular die, and then rapidly cooling to form a flat or annular laminated unstretched film It is better to adopt the co-extrusion method.

  Next, the laminated unstretched film is 2.5 times or more, preferably 2.7 times in each of biaxial directions perpendicular to each other, that is, in the film flow direction (longitudinal direction) and in the direction perpendicular thereto (lateral direction). More preferably, it is 2.9 times or more, and is 4.5 times or less, preferably 4.3 times or less, more preferably 4.0 times or less. When the stretching ratio in the biaxial stretching direction in the longitudinal direction and the transverse direction is less than 2.5 times, the stretching effect is small, the film strength is inferior, and the puncture strength is particularly lowered. In this case, the probability that the pinhole is opened due to the protrusion of the contents is increased. Further, when the stretching ratio in the biaxial stretching direction is larger than 4.5 times, the laminated film is liable to tear or break during stretching, so the upper limit of the stretching ratio is preferably within the above range.

  As the biaxial stretching method, a known stretching method can be adopted as long as it does not exceed the gist of the present invention, such as tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, and tubular simultaneous biaxial stretching. For example, in the case of the tenter-type sequential biaxial stretching method, the laminated unstretched film is heated to a temperature range of 50 to 110 ° C., stretched 2.5 to 5 times in the machine direction by a roll-type longitudinal stretching machine, and subsequently It can be manufactured by stretching 2.5 to 5 times in the transverse direction within a temperature range of 60 to 140 ° C. using a tenter type transverse stretching machine. Moreover, in the case of the tenter type simultaneous biaxial stretching and the tubular type simultaneous biaxial stretching method, for example, in the temperature range of 60 to 130 ° C., it is manufactured by stretching 2.5 to 5 times in each axial direction simultaneously in the longitudinal and lateral directions. can do.

  The biaxially stretched film stretched by the above method is subsequently heat treated. Dimensional stability at room temperature can be imparted by heat treatment. In this case, the heat treatment temperature should be selected within the range of 110 ° C. as the lower limit and 5 ° C. lower than the melting point of the polyamide-based resin as the upper limit. A stretched film can be obtained. The biaxially stretched film that has been sufficiently heat-set by the heat treatment operation is cooled and wound by a conventional method.

[Packaging container]
The stretched gas barrier film of the present invention is used in the form of a bag or a lid of a three-dimensional container such as a cup after laminating a heat-sealable thermoplastic resin by a general method and then heat-sealing the periphery.

  Packaging materials such as film can be used as packaging bags of various forms, and the bags can be produced by a known bag making method. Ordinary pouches with three- or four-side seals, pouches with gussets. , Standing pouches, pillow packaging bags, and the like, but are not limited to this example.

  The package of the present invention is useful as a package that can prevent the flavor of the contents from being lowered by oxygen. Contents that can be filled include wine, fruit juice, etc. for beverages, fruits, nuts, vegetables, meat products, infant foods, coffee, jam, mayonnaise, ketchup, cooking oil, dressing, sauces, boiled dairy products Others include, but are not limited to, examples such as pharmaceuticals, cosmetics, gasoline, and the like that easily deteriorate in the presence of oxygen.

  The invention is further illustrated by the following examples, but the invention is not limited to these examples.

<Oxygen absorbing resin>
A resin mixture containing nylon 6 pellets and cobalt stearate in a ratio of 95: 5 was extruded using a twin screw extruder under a nitrogen atmosphere. The extruded strand was quenched in a water bath, then pelletized and dried to obtain a cobalt masterbatch.
Next, while extruding nylon 6 pellets using a twin-screw extruder under a nitrogen atmosphere, polybutadiene (epoxy-functionalized polybutadiene-Elf-Atochem Poly BD600 / Poly BD605E) is made of nylon 6 so that the mass ratio is 5%. Added inside. The extruded strand was quenched in a water bath, then pelletized and dried to obtain an oxygen absorbing base resin.

<Oxygen absorption capacity>
Oxygen-absorbing resin pellets and cobalt master batch were dried and mixed in a weight ratio of 47: 1 so that the cobalt concentration was 100 ppm, extruded with a single screw extruder, cooled with a cast roll, and then a 50 μm film. Winded up. 5 g of this film was precisely weighed and sealed together with absorbent cotton and 400 ml of air with a few drops of water in an aluminum foil laminated PP film. The sealed bag was stored at 40 ° C., and the oxygen concentration after one month was measured. The oxygen concentration was measured with a PBI oxygen analyzer Dansenor CheckMate through a rubber syringe attached to the bag. The amount of oxygen absorbed was calculated from this concentration and divided by the weight of the sheet to calculate an oxygen absorption capacity of 9.3 ml / g.

<Puncture strength>
The specimen is conditioned for 24 hours under conditions of 23 ° C. and 50% RH, and the maximum load when a needle with a tip diameter of 0.5 mm penetrates the specimen at a speed of 50 mm / min under the same condition is measured. The numerical value divided by the specimen thickness (mm) was defined as the piercing strength. The film for the substrate for converting is required to have a piercing strength of 196 N / mm (20 kgf / mm) or more.

<Oxygen permeability>
Using an OXY-TRAN100 type oxygen permeability measuring device manufactured by Modern Control Co., Ltd., the oxygen permeability was measured at 23 ° C. and 50% RH. The oxygen permeability of the first gas barrier resin layer was determined by preparing a single biaxially stretched film (magnification MD / TD = 3/3, thickness 20 μm) and measuring the oxygen permeability under the above conditions. The thickness was converted.

Example 1
In order from the outer layer, nylon 6 (Novamid 1020 manufactured by Mitsubishi Engineering Plastics) / ethylene-vinyl alcohol copolymer (EVOH: Kuraray Eval L101B, ethylene content 27 mol% type) / (oxygen-absorbing base resin + cobalt masterbatch) (Cobalt content 100 ppm) mixed resin (oxygen-absorbing resin composition I) / ethylene-vinyl alcohol copolymer (EVOH: Kuraray Eval L101B ethylene content 27 mol% type) / nylon 6 (Mitsubishi Engineering Plastics) Novamid 1020) was co-extruded, closely cooled to a cast roll at 30 ° C., nylon 6 having a first layer of about 40 μm, EVOH having a second layer of about 20 μm, an oxygen-absorbing resin having a third layer of about 30 μm, The layer is EVOH of about 20 μm, and the fifth layer Obtained an unstretched laminated film of 3 types and 5 layers composed of nylon 6 having a thickness of about 40 μm.

  The obtained unstretched laminated film was stretched three times in the machine direction by a roll-type stretcher under the condition of 65 ° C., and then the end of the longitudinally stretched film was held with a tenter clip and 110 ° C. in a tenter oven. The film was stretched 3.5 times in the transverse direction under the conditions described above, and then heat-treated at 210 ° C. for 6 seconds. The heat-treated film is trimmed at both end portions corresponding to the gripping portion of the clip, and the product film portion after trimming is wound in a roll shape. The first layer is about 4 μm, the second layer is about 2 μm, A laminated biaxially stretched film having a total thickness of about 15 μm was obtained with a three-kind five-layer configuration in which three layers were 3 μm, the fourth layer was 2 μm, and the fifth layer was about 4 μm.

Furthermore, corona treatment was applied to the 5th layer side, 40μm LLDPE (TUX-FCS 40μ made by Tosero Co., Ltd.) and ether-based adhesive were used, and after aging, the LLDPE side was set as the inside and the surroundings were heat sealed to the inside Five bags of 30 cm length and 20 cm width, each containing about 300 ml of nitrogen, were made. This bag was stored in an environment of 23 ° C. and 50% RH. On the 30th day, five bags were opened, and the oxygen permeability of the film was measured under the condition of 23 ° C. and 50% RH using an OXY-TRAN100 type oxygen permeability measuring device manufactured by Modern Control. The oxygen permeability after 60 days was determined.
The oxygen permeation amount of this EVOH 27 mol% type 2 μm-thick film in air standard condition (23 ° C., 50% RH) for 60 days is 13 ml / m ² , so the oxygen absorption capacity is 32 ml / m ² . Is bigger. The evaluation results of the film are shown in Table 1.

(Example 2)
In Example 1, stretched film was prepared in the same manner as in Example 1 except that EVOH was changed to Nippon Synthetic Chemical Co., Ltd. Soarnol DC3203 (ethylene content 32 mol% type) and the thickness configuration was changed as shown in Table 1. And the obtained stretched film was measured and evaluated. The results are shown in Table 1.
In addition, since the oxygen permeation amount of this EVOH 32 mol% type film having a thickness of 2 μm in the standard condition in air (23 ° C., 50% RH) for 60 days is 25 ml / m ² , the oxygen absorption capacity is 53 ml / m ² . Is bigger.

(Examples 3 and 4)
In Example 2, a stretched film was produced by the same method as in Example 2 except that the thickness configuration was changed as shown in Table 1, and the obtained stretched film was measured and evaluated. The results are shown in Table 1.
(Example 5)
In Example 1, a stretched film was prepared by the same method as in Example 1 except that the thickness configuration was changed as shown in Table 1, and the obtained stretched film was measured and evaluated. The results are shown in Table 1.

(Example 6)
In Example 1, a stretched film was prepared by the same method as in Example 1 except that Aegis HFX (noncrystalline NY-based oxygen absorbent) manufactured by Honeywell was used as the oxygen-absorbing resin composition, and the obtained stretched film was obtained. The film was measured and evaluated. The results are shown in Table 1.
The oxygen absorption capacity of Aegis HFX manufactured by Honeywell was 10 ml / g.

(Comparative Example 1)
A stretched film was prepared in the same manner as in Example 1 except that the EVOH of the second layer and the fourth layer in Example 1 was Eval E101B (ethylene 44 mol% type) manufactured by Kuraray Co., Ltd., and the thickness was changed to 3 μm. The obtained film was measured and evaluated. The results are shown in Table 1.
The oxygen permeability of the EVOH (Kuraray Co., Ltd., ethylene content 44 mol% type) biaxially stretched film with a thickness of 3 μm is 49 ml / m ² · day · MPa (4.9 ml at 23 ° C. and 50% RH). / m ² · day · atm).

(Comparative Example 2)
In Example 1, EVOH of the second layer and the fourth layer was changed to MX-nylon (MXD6) manufactured by Mitsubishi Gas Chemical Company, and the thickness was changed to 5 μm. The obtained stretched film was measured and evaluated. The results are shown in Table 1.
The oxygen permeability of this polyamide biaxially stretched film having a thickness of 5 μm was 76 ml / m ² · day · MPa (7.6 cc / m ² · day · atm) under the conditions of 23 ° C. and 50% RH. .

(Comparative Example 3)
Nylon 6 (Mitsubishi Engineering Plastics Novamid 1020) / ethylene-vinyl alcohol copolymer (EVOH): Nippon Synthetic Chemicals Co., Ltd. Soarnol DC3203: ethylene content 32 mol% type) / Oxygen absorption base Resin + cobalt master batch (cobalt content 100 ppm) mixed resin (oxygen-absorbing resin composition I) / ethylene-vinyl alcohol copolymer (EVOH): Nippon Synthetic Chemical Co., Ltd. Soarnol DC3203: ethylene content 32 mol % Type) / nylon 6 (Mitsubishi Engineering Plastics Novamid 1020) co-extruded and cooled with cast roll, first layer is about 56μm nylon 6, second layer is about 25μm EVOH, third layer is about 62μm Oxygen absorbing resin, the fourth layer is about 25 μm VOH, and the fifth layer to obtain an unstretched laminated film of the three 5-layer consisting of each of nylon 6 about 56 .mu.m.

  The obtained unstretched laminated film was stretched 2.7 times in the longitudinal direction by a roll-type stretching machine at 55 ° C., and then the end of the longitudinally stretched film was held with a tenter clip, An attempt was made to stretch the film in the transverse direction by a factor of 4.6 under the condition of 100 ° C., but there were many breaks during the stretching, and the film could not be wound.

(Comparative Example 4)
Nylon 6 (Mitsubishi Engineering Plastics Novamid 1020) / ethylene-vinyl alcohol copolymer (EVOH): Nippon Synthetic Chemicals Co., Ltd. Soarnol DC3203: ethylene content 32 mol% type) / Oxygen absorption base Resin + cobalt master batch (cobalt content 100 ppm) mixed resin (oxygen-absorbing resin composition I) / ethylene-vinyl alcohol copolymer (EVOH): Nippon Synthetic Chemical Co., Ltd. Soarnol DC3203: ethylene content 32 mol % Type) / nylon 6 (Mitsubishi Engineering Plastics Novamid 1020) co-extruded and cooled with cast roll, first layer is about 26μm nylon 6, second layer is about 12μm EVOH, third layer is about 29μm Oxygen absorbing resin, 4th layer is about 12μm EVOH, and the fifth layer to obtain an unstretched laminated film of the three 5-layer consisting of each of nylon 6 about 26 .mu.m.

  The obtained unstretched laminated film was stretched 2.4 times in the longitudinal direction by a roll-type stretching machine under the condition of 55 ° C., and then the end of the longitudinally stretched film was held with a tenter clip. The film was stretched 2.4 times in the transverse direction under the condition of 100 ° C., and then heat-treated at 210 ° C. for 6 seconds. The heat-treated film is trimmed at both ends corresponding to the gripping part of the clip, and the product film part after trimming is wound up into a roll shape. The first layer is about 4.5 μm and the second layer is about 2 μm. A laminated biaxially stretched film having a total thickness of about 15 μm was obtained with a three-kind five-layer structure in which the third layer was 5 μm, the fourth layer was 2 μm, and the fifth layer was about 4.5 μm. However, the unstretched portion remained, the thickness accuracy was poor, and it was in a state where it could not be put to practical use, so no further measurement was performed.

(Comparative Example 5)
A stretched film was prepared in the same manner as in Example 2 except that the inner gas barrier layer was omitted in Example 2, and the obtained film was measured and evaluated. The results are shown in Table 1. It can be seen that the oxygen absorption capacity of the oxygen absorption layer has been saturated during film production.

(Comparative Example 6)
Nylon 6 (Mitsubishi Engineering Plastics Novamid 1020) / ethylene-vinyl alcohol copolymer (EVOH): Nippon Synthetic Chemicals Co., Ltd. Soarnol DC3203: ethylene content 32 mol% type) / Oxygen absorption base Resin + cobalt master batch (cobalt content 100 ppm) mixed resin (oxygen-absorbing resin composition I) / ethylene-vinyl alcohol copolymer (EVOH): Nippon Synthetic Chemical Co., Ltd. Soarnol DC3203: ethylene content 32 mol type ) / Nylon 6 (Mitsubishi Engineering Plastics Novamid 1020) is co-extruded and cooled with a cast roll, the first layer is about 4.5 μm nylon 6, the second layer is about 2 μm EVOH, and the third layer is about 5 μm Oxygen absorbing resin, 4th layer EVO of about 2 μm And the fifth layer to prepare an unstretched laminated film of the three 5-layer consisting of about each of 4.5μm nylon 6, were measured and the measurement of the unstretched laminated film obtained. The results are shown in Table 1.
In addition, the oxygen permeability of this EVOH (Nippon Synthetic Chemical Co., Ltd., ethylene content 32 mol% type) unstretched film with a thickness of 2 μm is 35 ml / m ² · day · under 23 ° C. and 50% RH conditions. MPa (3.5 ml / m ² · day · atm).

From Table 1, the stretched gas barrier film in the range of the present invention was able to stably maintain a high oxygen gas barrier property for a long period of time, and good film strength was obtained (Examples 1 to 4). On the other hand, when the oxygen permeability of the gas barrier resin layer is higher than 30 ml / m ² · day · MPa (Comparative Examples 1 and 2), the stretching ratio is outside the range of the present invention (Comparative Examples 3 and 4). In the case of the unstretched film (Comparative Example 5), no film having both high oxygen barrier performance and film strength was obtained.
From this, it can be seen that according to the present invention, it is possible to maintain a high gas barrier performance and to provide a gas barrier stretched film having film strength.

It is sectional drawing (the 1) of the suitable gas barrier property stretched film of this invention. It is sectional drawing (the 2) of the suitable gas-barrier stretched film of this invention.

Explanation of symbols

1 Gas Barrier Stretched Film 2 Polyamide Resin Layer 3 First Gas Barrier Resin Layer 4 Oxygen Absorbing Resin Layer 5 Second Gas Barrier Resin Layer 6 Polyamide Resin Layer

Claims (7)

At least four layers of a polyamide-based resin layer, a first gas barrier resin layer, an oxygen absorbing resin layer, and a second gas barrier resin layer are provided on both sides of the oxygen absorbing resin layer, and the first gas barrier resin layer and the second gas barrier property. An ethylene-vinyl acetate copolymer soap having a resin layer and a gas barrier resin constituting the first gas barrier resin layer and / or the second gas barrier resin layer having an ethylene content of 32 mol% or less. a compound, wherein said first oxygen transmission rate of gas barrier resin layer under conditions of 23 ℃ · 50% RH 30ml / m2 · day · atm (3cc / m2 · day · atm) or less, and the oxygen The absorbent resin layer is a film obtained by stretching a laminated film, which is a resin composition containing an oxidizable resin and a transition metal catalyst, at a magnification of 2.5 to 4.5 times in two orthogonal directions. The piercing strength is 196N / mm (20 Kgf / mm) to 500 N / mm and oxygen permeability at 23 ° C. and 50% RH is 1 ml / m 2 · day · MPa (0.1 cc / m 2 · day · atm) or less The thickness of the oxygen-absorbing resin layer that can be maintained for at least 60 days is 1 to 10 μm, the thickness of each of the first gas barrier resin layer and the second gas barrier resin layer is 1 to 10 μm, and the total thickness is 40 μm. A gas barrier stretched film characterized by the following: The oxygen permeability of the first gas barrier resin layer is 30 ml / m 2 · day · MPa (3 cc / m 2 · day · atm) at 23 ° C and 50% RH, and is stored at 23 ° C and 50% RH for 60 days. 2. The gas barrier property according to claim 1, wherein an oxygen absorption amount per unit area of the oxygen-absorbing resin layer is greater than an oxygen permeation amount per unit area of the first gas barrier resin layer when stored under the above conditions. Stretched film. The stretched gas barrier film according to claim 1 or 2 , wherein the oxygen-absorbing resin constituting the oxygen-absorbing resin layer is a resin composition containing a polyamide resin as a main component and containing an oxidizable resin and a transition metal catalyst. . The stretched gas barrier film according to any one of claims 1 to 3 , wherein the polyamide resin constituting the polyamide resin layer is a resin composition containing an aliphatic polyamide resin as a main component. Polyamide-based resin layer, a first gas barrier layer, the oxygen-absorbing resin layer, and according to any one of claims 1 to 4 is molded laminated film having at least four layers of the second gas barrier resin layer by coextrusion Gas barrier stretched film. Gas barrier packaging material using the gas barrier stretched film according to any one of claims 1-5. Gas barrier package using the gas barrier stretched film according to any one of claims 1-5.

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