JP2011000869A - Multilayered film with gas-barrier property and bottom material for deep drawing packages using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide packaging material excellent in transparency, moldability, pinhole resistance, and rigidity, capable of suppressing an oxygen transmission amount to almost zero even after heating sterilization by hot water or water vapor, capable of maintaining high oxygen gas barrier properties for a long period of time even if the packaging material is conserved under high temperature and high humidity, and capable of suppressing transfer of smell which might be generated when oxygen-absorbing resin absorbs oxygen to the content side.SOLUTION: A film with gas-barrier properties, which is a multilayered film formed of at least three layers, is characterized by having an oxygen absorbing resin layer (a), a cyclic polyolefin layer (b) inside the layer (a), and a heat sealing resin (c) at the innermost layer. The oxygen transmission rate of 0.01fm/s×Pa(1 ml/m×day×MPa) or smaller than that is maintained during at least 180 days under 23°C and 50%RH.

Description

  The present invention relates to a gas barrier film that can be suitably used for food containers to be sterilized by heating. The plastic material suppresses the oxygen permeation amount to a remarkably low level even under the heat sterilization conditions in which the gas barrier property is lowered by the action of heat and moisture. In addition, it provides a transparent packaging material that can maintain a high oxygen gas barrier property for a long period of time even in a storage state after heat sterilization, and the odor that can be generated by the oxidation reaction of the oxygen-absorbing resin is transferred. The present invention relates to a gas barrier co-extrusion composite film having an oxygen absorption function suitable for packaging foods, medical products, medicines, etc.

  Conventionally, metal cans, glass bottles, and various plastic containers are used as food containers that are sterilized by heat and stored for a long time. However, in the case of plastic containers, the amount of oxygen permeated from the plastic material cannot be ignored. There was a problem in the preservation of the food. In particular, when sterilizing by heating with hot water or steam, such as boil sterilization, a high temperature close to 100 ° C. acts on the plastic material under high humidity, so it is a big problem to maintain the gas barrier property of the plastic container. there were. Therefore, as a gas barrier packaging material for storing food to be sterilized for a long period of time, a composite film mainly composed of polypropylene (PP) or high density polyethylene (HDPE) having high moisture resistance has been used (for example, , See Patent Document 1). However, in order to impart moisture resistance to such a composite film, the layer of polypropylene (PP) or polyethylene (HDPE) must be thickened. If the layer of polypropylene (PP) or polyethylene (HDPE) is thickened, the moldability of the composite film (hereinafter also referred to as “deep drawability”) deteriorates when deep drawing is performed. There is a problem that a deep drawing molding equipment using (equipment for supplementing deep drawing moldability) is necessary, and transparency is further deteriorated. Also, under heat sterilization conditions, the oxygen permeability coefficient of the gas barrier resin increases as the water vapor permeability coefficient increases, and there is a drawback that oxygen permeates into the container during heat sterilization and oxidatively degrades the content food. It was.

Moreover, in terms of gas barrier properties, a transparent and high oxygen barrier packaging material such as a biaxially stretched polyester film (OPET), a biaxially stretched polyamide film (ONY), etc., a vapor deposited film, a gas barrier, Films that are multilayered with a conductive resin EVOH, MXD-NY, or the like are used. However, this vapor-deposited film has a drawback that the vapor barrier film is easily damaged when the heat seal layer is laminated or printed, or by bending during use, and the oxygen barrier property is remarkably impaired. In addition, the conventional multi-layered film made of gas barrier resin EVOH, MXD-Ny, etc. is a passive method in which oxygen permeating the outside of the container is barriered, and conditions under which heat and moisture act simultaneously. That is, under the conditions of heat sterilization with hot water or steam, the oxygen permeation coefficient of the packaging material is very large compared to room temperature. Under this condition, the oxygen permeation amount of the packaging material can be suppressed to a low level. It was a big issue. In particular, it has been difficult to apply to foods that are sensitive to even a small amount of oxygen, such as confectionery, rice cakes, cooked rice, seasonings, dressings, mayonnaise, soy sauce, and fresh foods.

Therefore, at present, in addition to suppressing the invasion of oxygen from the outside with respect to gas barrier packaging using conventional vapor deposition film, EVOH, etc., it also absorbs residual oxygen in the container and keeps it below the initial oxygen concentration. Attention has been focused on the active method of being able to do this. For example, a method is also known in which an oxygen absorbent or the like is included in a packaging material, and oxygen that permeates is collected to reduce the apparent oxygen permeability. Is blended with a predetermined resin and used as a container wall of a packaging material, and has an advantage of high oxygen absorption performance. However, since the resin to be blended needs to be colored in a unique hue, there is a restriction that it cannot be used in the field of packaging that requires transparency. Further, since this packaging material reacts with the metal foreign object detector, there are problems in that the foreign object detector cannot be used, and there is a possibility of discharge and ignition by heating with a microwave oven.

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 2). 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. Therefore, in order to prevent the odor from moving to the contents side, a configuration in which a gas barrier resin is disposed between the oxygen-absorbing resin layer and the heat seal resin layer (see Patent Documents 3 and 4), or an oxygen-absorbing resin layer There has also been proposed an oxygen-absorbing container that can maintain an oxygen-absorbing function for 3 months in a container such as a bottle by laminating gas barrier resin layers on both sides (see Patent Document 5). However, Documents 3 and 5 relate to a container having a large thickness such as a bottle application, and do not relate to a gas barrier film designed by optimally combining an oxygen absorbing resin layer and a gas barrier resin layer. Reference 4 relates to a film obtained by dry-laminating a stretched substrate and mainly relates to a bag (pouch) or the like, which is also a gas barrier film designed by optimally combining an oxygen-absorbing resin layer and a gas barrier resin layer. In the soft packaging field, especially in the deep-drawing packaging field, the thickness of the entire film is reduced by deep drawing compared to before molding, and oxygen cannot be absorbed in the thinnest part of the corner, and oxygen can permeate. However, it is still difficult to use in practice because of the unpleasant odor caused by oxygen absorption. Also, when sterilizing by heating with hot water or steam, such as boil sterilization, the oxygen permeation coefficient of the oxygen-absorbing resin increases with the increase of the water vapor permeation coefficient. There was a defect that oxygen permeated into the container to oxidize and deteriorate the content food. Further, as disclosed in Patent Document 6, it has been proposed to mix an oxygen scavenger or oxygen scavenger and a hygroscopic agent on at least one side of the gas barrier resin. Necessary and inefficient.

Japanese Patent Laid-Open No. 06-305099 JP-T-3-503153 JP 2004-25664 A Japanese Patent Application Laid-Open No. 06-115569 Japanese Patent Laid-Open No. 2002-240813 JP-A-8-118551

  The present invention has been made to solve the above-described problems of the prior art, and relates to a gas barrier film that can be suitably used for food containers to be heat sterilized. The plastic material has a gas barrier property that is lowered by the action of heat and moisture. Even under heat sterilization conditions, the amount of oxygen permeation can be suppressed to almost zero, and even when stored for a long time under high temperature and high humidity conditions, the oxygen absorption function does not deteriorate. An object of the present invention is to provide a transparent packaging material that can maintain a high oxygen gas barrier property and suppress the odor that can be generated when the oxygen-absorbing resin absorbs oxygen from moving to the contents side.

  The present inventor has intensively studied to achieve the above-mentioned problems. As a result, an oxygen-absorbing resin layer having a predetermined amount of oxygen-absorbing ability, and a multilayer film having a cyclic polyolefin layer on the inside thereof have been developed for a long time. It has been found that even under heat sterilization conditions in which gas barrier properties are reduced by the action of heat and moisture, high oxygen absorbability can be maintained and generation of unpleasant odor accompanying oxygen absorption is suppressed. It came to be completed.

That is, the present inventor has solved the above-mentioned problem with a multilayer film comprising at least three layers, an oxygen-absorbing resin layer (a), a cyclic polyolefin layer (b) on the inner side, and a heat-sealable resin (c on the innermost layer). A gas barrier film characterized by having an oxygen permeability of 0.01 fm / s · Pa (1 ml / m ² · day · MPa) or less at 23 ° C. and 50% RH for at least 180 days. This is solved by providing a multilayer film.

  In the present invention, since an oxygen-absorbing resin layer having a predetermined oxygen-absorbing ability and a cyclic polyolefin resin layer having a predetermined water-vapor barrier function are disposed on the inside thereof, even after heat sterilization with hot water or water vapor, oxygen When the packaging material is stored under high temperature and high humidity, it can maintain a high oxygen gas barrier property for a long period of time, and the oxygen absorbing resin absorbs oxygen. It can suppress that the odor which may be generated transfers to the contents side.

Further, in the present invention, particularly when the oxygen-absorbing resin is a composition containing an ethylene-vinyl acetate copolymer saponified resin or a polyamide resin as a main component and an oxidizable resin and a transition metal catalyst, It has excellent initial oxygen absorption ability, and can exhibit excellent gas barrier performance especially after heat sterilization.

In the present invention, when a packaging material or a package is produced using the above gas barrier film, it is possible to stably maintain an excellent oxygen barrier property and an excellent oxygen absorption capacity for a long period of time, particularly a soft packaging material having a high gas barrier property, Deep-drawing packaging materials, soft packaging bodies, and deep-drawing packaging bodies can be provided.

FIG. 2 is a schematic view showing a cross-sectional structure of a gas barrier multilayer film.

Hereinafter, the gas barrier film of the present invention, and the packaging material and package using the film will be described in detail.
In this specification, “the B layer is laminated on the inside of the A layer” means that the B layer is closer to the contents than the A layer when a package is produced using the gas barrier film of the present invention. "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.

[Gas barrier properties]
The gas-barrier film of the present invention has a gas barrier property that maintains an oxygen permeability of 0.01 fm / s · Pa (1 ml / m ² · day · MPa) or less at 23 ° C. and 50% RH for at least 180 days. It is said.

[Layer structure]
Next, the layer structure of the gas barrier film of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view (No. 1) of a preferred gas barrier film of the present invention. A thermoplastic resin layer optionally provided as an outer layer, an oxygen-absorbing resin layer (a) and a cyclic polyolefin resin layer (b) arranged on the inside, and a heat-sealable thermoplastic resin layer (c) provided on the innermost layer ing.

  As shown in FIG. 1, the gas barrier film 1 of the present invention has a configuration comprising at least three layers of an oxygen-absorbing resin layer (a), a cyclic polyolefin layer (b), and a heat seal layer (c). Even if the oxygen barrier property is lowered under the condition where hot water or steam acts, that is, the heat sterilization condition, by arranging the cyclic polyolefin resin layer (b) inside the oxygen-absorbing resin layer (a), the packaging Oxygen from outside the body does not permeate inside. In addition, the cyclic polyolefin layer (b) is arranged inside the oxygen-absorbing resin layer (a), and the water vapor barrier property in the packed product is remarkably improved, so that the oxidation reaction of the oxygen-absorbing resin is promoted even during heat sterilization. The load is reduced so as not to lose the absorption function. In general, the oxidation reaction of an oxidizable component in an oxygen-absorbing resin promotes the reaction rate as the moisture content increases and the temperature increases.

  Further, even after heat sterilization, the cyclic polyolefin layer disposed inside the oxygen-absorbing resin layer (a) can suppress the moisture permeability coefficient inside the pack product to a low level, so that the oxygen absorption function is not immediately deactivated. The rate of the oxidative absorption reaction can be delayed, and the oxygen barrier zero period can be extended. In addition, cyclic polyolefin resin does not have an odor barrier function similar to EVOH and MXD-Ny, but has a higher glass point transfer point than ordinary polyolefin resin, so the molecular chain of the amorphous part does not move at room temperature, and oxygen absorbency It is difficult to pass odors (aldehyde, ketone, etc.) that may be generated from the resin layer (a).

The cyclic polyolefin layer must be disposed on both sides or inside of the oxygen-absorbing resin.
The configuration in which the cyclic polyolefin layer is disposed outside the oxygen absorbing resin is not preferable because the oxygen absorbing function does not function in a relatively short time. That is, during and after heat sterilization, the cyclic polyolefin layer does not allow the moisture content to permeate to the outside of the pack product, so the relative humidity of the oxygen-absorbing resin increases as the moisture permeability coefficient inside the pack product increases. turn into. For this reason, the oxidation reaction rate is accelerated in the oxygen-absorbing resin layer, so that the oxygen-absorbing function is exhibited in a short time.

  Although not shown in FIG. 1, an adhesive resin layer may be interposed between the oxygen-absorbing resin layer (a) and the cyclic polyolefin resin layer (b) for the purpose of improving the interlayer adhesive strength. it can. However, the oxygen-absorbing resin is a resin mainly composed of an ethylene-vinyl acetate copolymer saponified product or a polyamide-based resin, and an ethylene-vinyl acetate copolymer saponified product or a polyamide-based resin is arranged on both sides of the oxygen-absorbing resin. In this case, since the adhesiveness of both resin layers is relatively high, both layers can be laminated without interposing the adhesive resin layer.

Although the gas barrier film of the present invention has the above layer structure, the thickness of the entire gas barrier film is 60 μm or more, preferably 80 μm or more, more preferably 100 μm or more, 500 μm or less, preferably 400 μm or less, more preferably. When it is used as a soft packaging material, it is desirably 250 μm or less, preferably 200 μm or less, and more preferably 150 μm or less. The thicknesses of the oxygen-absorbing resin layer (a), the cyclic polyolefin resin layer (b) and the heat-sealable resin layer (c) will be described later.

  Examples of the layer configuration that can be adopted by the gas barrier film of the present invention include the following embodiments.

<Layer structure of film for deep drawing>
In the film of the present invention, the order of the layer structure is particularly limited as long as at least the oxygen-absorbing resin layer (a) is disposed in the outer layer or the intermediate layer, and the cyclic polyolefin resin layer (b) is disposed inside the oxygen-absorbing resin layer (a). However, the oxygen-absorbing resin layer is the A layer, the cyclic polyolefin resin layer is the B layer, the polyamide (hereinafter sometimes referred to as “PA”) layer is the C layer, and the polyethylene terephthalate (hereinafter referred to as “PET”). .) Layer is D layer, polyethylene (hereinafter sometimes referred to as “PE”) layer is E layer polypropylene (hereinafter sometimes referred to as “PP”) layer is F layer, adhesive resin layer is G layer, heat When the sealing resin layer is represented as an H layer, the following layer configurations (1) to (14) can be exemplified.
(1) C / G / C / A / G / B
(2) C / G / C / A / G / B / H
(3) D / G / C / A / G / B
(4) D / G / C / A / G / B / H
(5) E / G / C / A / G / B
(6) E / G / C / A / G / B / H
(7) A / C / G / B
(8) A / C / G / B / H
(9) E / G / C / A / G / B
(10) E / G / C / A / G / B / H
(11) F / G / A / C / G / B
(12) F / G / A / C / G / B / H
(13) F / C / G / A / G / B
(14) F / C / G / A / G / B / H
Among these, preferred layer structures are (2), (4), (6), (8), (10), and (14).

[Oxygen-absorbing resin layer (a)]
In the gas barrier film of the present invention, the oxygen-absorbing resin used in the oxygen-absorbing resin layer (a) is 0.01 fm / s · at 23 ° C. and 50% RH when used in combination with the gas barrier resin layer. Although it is not particularly limited as long as it can maintain oxygen permeability of Pa (1 ml / m ² · day · MPa) or less for at least 180 days, the oxidizable resin (S) and the transition metal catalyst (M) The resin composition containing is used suitably. From the viewpoint of oxygen absorption capacity and oxygen absorption rate, a resin composition containing an oxidizable resin (S) containing a carbon-carbon double bond substantially only in the main chain and a transition metal catalyst (M) is preferred.

    The oxidizable resin (S) is a resin that is oxidized with oxygen in the air by the action of the transition metal catalyst (M). Specifically, (i) a resin containing a carbon side chain, (ii) xylylene Examples thereof include a group-containing polyamide resin, (iii) an ethylenically unsaturated group-containing polymer, and (iv) a polyether-containing polymer. Further, the oxidizable resin (S) is a resin having a main component of a general thermoplastic resin, for example, a polyamide resin, a polyester resin, a polyolefin resin, etc. (that is, a base resin), and a transition metal catalyst. It is also preferred to be used as an oxygen-absorbing resin composition by being mixed and dispersed together with (M).

Oxygen absorption in the composition containing the oxidizable resin (S) and the transition metal catalyst (M) is:
This 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 thermoplastic polyesters, especially aliphatic polyesters, (
C) Branched chain-containing thermoplastic polyamides derived from branched chain aliphatic dicarboxylic acids, aliphatic diamines, aliphatic aminocarboxylic acids, or lactams, particularly aliphatic polyamides.

As the xylylene group-containing polyamide resin (ii), a xylylene group-containing polyamide resin,
Particularly, polyamides derived from a diamine component mainly composed of xylylenediamine and a dicarboxylic acid component can be mentioned. The xylylene group-containing polyamide resin (ii) is a transition metal catalyst (M
) Is known to have oxidizability in combination. That is, a transition metal catalyst (M
) Generate a radical by extracting a hydrogen atom from the methylene chain (especially the methylene chain adjacent to the arylene group) of the xylylene group-containing polyamide resin, and oxidation proceeds by the same reaction mechanism as described above.

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 hexamethylenediamine, alicyclic diamines such as piperazine, para-bis (2
Aromatic diamines such as aminoethyl) benzene, aromatic dicarboxylic acids such as terephthalic acid, lactams such as ε-caprolactam, ω-aminocarboxylic acids such as 7-aminoheptanoic acid, and aromatic aminos such as para-aminomethylbenzoic acid. A copolymer obtained by copolymerizing carboxylic acid or the like can be used. 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.
-Chain non-conjugated dienes such as hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene; methyltetrahydroindene, 5-ethylidene- 2-norbornene, 5-methylene-2-norbornene, 5
-Cyclic non-conjugated dienes such as isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, dicyclopentadiene; 2,3-diisopropylidene-5 Examples include triene such as norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 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. As a monomer used in combination with polyene, C2-C20 alpha olefin, for example, ethylene,
Propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 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, 1
Examples include 2-ethyl-1-tetradecene, and other monomers such as styrene, vinyl toluene, acrylonitrile, methacrylonitrile, vinyl acetate, methyl methacrylate, and ethyl acrylate can also be used.

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-
Although diene rubber (EPDM) etc. can be mentioned, it is 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.

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 composition can be composed only of an oxidizable resin (S) and a transition metal catalyst (M), but is used by mixing and dispersing other thermoplastic resins as main components. Is preferred. By adjusting and using the amount of mixing / dispersing, the oxygen absorption capacity as the oxygen-absorbing resin (a) 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 facilitate the dispersion of the oxidizable resin (S) in the thermoplastic resin, it is preferable to introduce an epoxy or an anhydrous functional group into the oxidizable resin.

The introduction of an epoxy or anhydrous functional group or the like 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 other resin of the acid-modified polyene polymer (
(Matrix resin) is well dispersed and oxygen is smoothly absorbed. Also,
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 as the main component in the oxygen-absorbing resin composition, a general thermoplastic resin usually used for film applications is used. In particular, an ethylene-vinyl acetate copolymer saponified product (EVOH) or a polyamide-based resin is preferable because it can easily improve the strength of the film.

The ethylene content of the useful saponified ethylene-vinyl acetate copolymer is not particularly limited, but is preferably 27 to 47 mol%, and preferably 32 to 44 mol% from the viewpoint of film formation stability. More preferably. Further, EVOH has a saponification degree of 90% or more, preferably 95 mol% or more. By maintaining the ethylene content and saponification degree of EVOH within the above ranges, the coextrudability of the film of the present invention and the strength of the film can be improved.

Useful aliphatic polyamide homopolymers include poly (4-aminobutyric acid) (nylon 4
), Poly (6-aminohexanoic acid) (also known as nylon 6, poly (caprolactam)), poly (7-aminoheptanoic acid) (nylon 7), poly (8-aminooctanoic acid)
(Nylon 8), poly (9-aminononanoic acid) (nylon 9), poly (10-aminodecanoic acid) (nylon 10), poly (11-aminoundecanoic acid) (nylon 11), poly (
12-aminododecanoic acid) (nylon 12), poly (hexamethylene adipamide) (nylon 6,6), poly (hexamethylene sebacamide) (nylon 6,10), poly (heptamethylene pimeramide) ( Nylon 7,7), poly (octamethylenesuberamide) (nylon 8,8), poly (hexamethylene azelamide) (nylon 6,9), poly (nonamethylene azelamide) (nylon 9,9), poly ( Decamethylene azelamide) (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-azelaamide caprolactam copolymer (nylon 6,
6/6, 9/6), poly (tetramethylenediamine-co-oxalic acid) (nylon 4,2)
, Polyamides of n-dodecanedioic acid and hexamethylenediamine (nylon 6,12), polyamides of dodecamethylenediamine and n-dodecanedioic acid (nylon 12,12), and blends and copolymers thereof, and Other polyamides not specifically mentioned.

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

The polyamide-based resin can further include nanometer-scale dispersed clay for the purpose of improving the gas barrier property of the oxygen-absorbing resin (a). 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,
Examples include transition metal salts such as arachidonic acid, formic acid, oxalic acid, 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 above oxygen-absorbing resin composition containing a thermoplastic resin as a main component, the transition metal catalyst (M) is 10 ppm or more, preferably 50 ppm or more, 200 ppm or less with respect to the thermoplastic resin contained as the main component. It is desirable that it is contained at a ratio of preferably 100 ppm or less. Various means can be used as a method of blending the transition metal catalyst (M) with the thermoplastic tree. For example, the transition metal catalyst (M) can be simply dry blended with the thermoplastic resin, but since the transition metal catalyst (M) is a small amount compared to the thermoplastic resin, in order to perform the blending homogeneously, The transition metal catalyst (M) is dissolved in an organic solvent, the solution and a powder or granular resin are mixed, and if necessary, the 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.

  Mixing of the oxidizable polymer component and the transition metal catalyst (M), and subsequent storage is performed in a non-oxidizing atmosphere so that oxidation in the previous stage of the oxygen-absorbing resin composition does not occur. Good. 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 oxidizable 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 an oxygen-absorbing resin composition. 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 may be desirable for improved processing of the composition as well as for improving the products and products formed from the composition. Examples of such additives are oxidation and heat stabilizers, lubricants, mold release agents, flame retardants, oxidation inhibitors, dyes,
Such as pigments and other colorants, UV stabilizers, organic or inorganic fillers including particle and fiber 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 (a) can be appropriately determined so as to obtain a desired oxygen-absorbing ability, but is preferably 15 μm or more, more preferably 20 μm or more, and further preferably 30 μm or more, 60 μm. Hereinafter, it is preferably 50 μm or less, more preferably 40 μm or less. If the thickness of the oxygen-absorbing resin layer is 10 μm or more, high oxygen gas barrier properties can be maintained for a long time even after deep drawing, and if it is 40 μm or less, sufficient oxygen absorption can be maintained and economical This is also preferable.

[Cyclic polyolefin resin layer (b)]
The composite film of the present invention is provided with a cyclic polyolefin layer (b) for the purpose of improving the moisture resistance of the composite film. Cyclic polyolefin is a polymer having an alicyclic hydrocarbon group in the molecule. The cyclic polyolefin used for the cyclic polyolefin layer has a glass transition temperature (hereinafter also referred to as Tg) of 60 ° C. or higher, preferably 65 ° C. or higher, more preferably 70 ° C. or higher, and an upper limit of 140 ° C. or lower, preferably 135. ° C or lower, more preferably 130 ° C or lower.
COP with a T g of less than 60 ° C is likely to cause problems in extrusion processability, such as winding around a screw or sticking between pellets, and softens when the temperature is high even at room temperature. The shape as a container cannot be maintained, and a rigid and firm package cannot be obtained. Conversely, if it exceeds 80 ° C., it is necessary to increase the extrusion temperature, and at the same time, there is a problem of causing thermal deterioration of the oxygen-absorbing EV O H that is inferior in heat resistance, and post-processing such as deep drawing. There is a problem that it becomes difficult. In particular, when E V O H is extruded at a high temperature, cross-linking between molecules proceeds and problems such as blistering due to an increase in viscosity occur. Therefore, it is required to suppress the extrusion temperature and the die temperature to 2 40 ° C. or less. Use of C O P having g of 80 ° C. or lower is effective. By setting the Tg of the cyclic polyolefin to 60 ° C. or higher, there is no softening of the film even when the temperature is high during storage of the film, and there is no softening of the film even when the film is wound around a paper tube due to the softening of the film at a high temperature. It is possible to prevent winding and squeezing in a state where the film is wound around a paper tube due to the softening of the film at a high temperature, and the packaging body is not softened due to the softening of the film at a high temperature so that the shape of the packaging body cannot be maintained. In addition, by setting the Tg of the cyclic polyolefin to 140 ° C. or less, good deep drawability can be imparted, and it is not necessary to set the extrusion temperature high during film formation. Since heat is not applied as necessary, it is possible to suppress defects, gels, and the like due to thermal degradation.

The lower limit of the thickness of the cyclic polyolefin layer (b) is 40 μm or more, preferably 50 μm or more, and more preferably 60 μm or more. The upper limit is 500 μm or less, preferably 400 μm or less, and more preferably 350 μm or less. By setting the lower limit of the thickness of the cyclic polyolefin layer to 40 μm or more, sufficient moisture resistance and moldability can be obtained, and by making the upper limit of the thickness of the cyclic polyolefin layer 500 μm or less, a composite that can be deep drawn It can be a film.

As the cyclic polyolefin, a cycloolefin copolymer (COC) and a cycloolefin polymer (COP) can be used. Here, the cycloolefin copolymer (COC) refers to a cyclic polyolefin obtained by addition polymerization of dicyclopentadiene or a dicyclopentadiene derivative and an α-olefin. The cycloolefin polymer (COP) refers to a cyclic polyolefin obtained by ring-opening polymerization of a cyclic olefin. From the viewpoint that the Tg of COC can be controlled by adjusting the content of the cyclic olefin monomer, it is desirable to use a cycloolefin copolymer, but this is not the main purpose of adding a limitation.

When the cyclic polyolefin contains low density polyethylene (LDPE) and / or linear low density polyethylene (LLDPE), the film can be appropriately softened. If the blending amount is too large, the water vapor barrier property is deteriorated. Therefore, the blending amount is preferably 20% or less, more preferably 10% or less, and most preferably used alone without blending.

Cyclic polyolefin resin has high characteristics regarding water vapor barrier properties under high temperature and high humidity compared to high density polyethylene (HD), polypropylene (PP) and the like. Therefore, even if high-temperature sterilization treatment with hot water is performed, if there is a cyclic polyolefin layer, the oxygen-absorbing resin is oxidized in order to prevent moisture contained in the contents from reaching the oxygen-absorbing resin layer. The load is reduced so that the absorption function is not lost. In addition, it is possible to extend the duration of oxygen absorption even after the high temperature sterilization treatment.

The cyclic polyolefin resin needs to be disposed inside or on both sides of the oxygen-absorbing resin layer, and is preferably disposed only inside the oxygen-absorbing resin layer from the viewpoint of cost.

As described above, the configuration in which the cyclic polyolefin layer is arranged outside the oxygen-absorbing resin does not allow moisture in the contents to permeate outside the pack product during or after heat sterilization. This is because as the inner moisture permeability coefficient increases, the relative humidity of the oxygen-absorbing resin increases, and the oxygen-absorbing function cannot be exhibited in a relatively short time.

[Heat-sealable resin layer (c)]
In the present invention, the heat-sealable resin layer (c) is laminated inside the cyclic polyolefin resin layer (b). The resin used in the heat-sealable resin layer may be any heat-sealable thermoplastic resin, and is appropriately determined in consideration of the material of the adherend. Examples of heat-sealable thermoplastic resins include olefin resins, styrene resins, ester resins, ethylene resins having adhesion to ester resins, styrene resins, or adhesion to styrene resins. Examples thereof include ethylene resins, and olefin resins are preferably used from the viewpoints of seal strength and easy handling.

As the olefin resin, very low density polyethylene (VLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE) or high density polyethylene (HDPE)
, Ethylene-based resins such as linear low density polyethylene (LLDPE); ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene -Methyl acrylate copolymer (E
MA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH)
, Ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMA
A) ethylene-based copolymers; ethylene-acrylic acid copolymer neutralized products, ethylene-
Metal neutralized methacrylic acid copolymer (for example, at least one of its carboxyl groups
0 mol%, preferably 10 to 60 mol% neutralized with ions of metals such as sodium and zinc); ionomer, homopolypropylene, block copolymer or random copolymer type polypropylene resin, ethylene-propylene Copolymer, polybutene-1, ethylene-butene-1 copolymer, propylene-butene-1 copolymer, ethylene-propylene-
Butene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer,
Examples thereof include an ethylene-ethyl acrylate copolymer and an ethylene-ethyl methacrylate copolymer.

Examples of the styrenic resin include styrene copolymers in which a small amount of rubber and other vinyl monomers are copolymerized with styrene monomers in addition to polystyrene. Examples of other vinyl monomers include styrene monomers such as α-methylstyrene and p-methylstyrene, acrylonitrile, methyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid, and maleic anhydride. Can be mentioned. Moreover, the usage-amount of rubber | gum content is 0.1-20 mass% normally, and the usage-amount of another vinyl-type monomer is 0.1-30 mass% normally. Preferred examples of the styrene resin include polystyrene and high impact polystyrene (HIPS) which is a copolymer of diene rubber and styrene.

These resins can be used alone or in combination. The heat-sealable resin layer (c) may be composed of two or more layers made of different resins as necessary.

Among them, it is preferable to use a linear low density polyethylene resin (LL) for the sealing layer of the composite film of the present invention and to arrange the COP adjacent to the linear low density polyethylene resin (LL). (Hot tackiness: easy seal strength in a hot state immediately after sealing, contaminant sealing property: sealing property in a state where foreign matter is present on the surface of a sealing material such as oil) is inferior. By using LL having good interlayer adhesion with COP as a seal layer and arranging COP adjacent thereto, a packaged product having good sealability and seal strength can be obtained. At this time, if L DPE is used for the sealing layer, the interlayer strength with the COP becomes insufficient, and the possibility of bag breakage appears. Conversely, when it is desired to further increase the interlayer strength, it is effective to use metallocene PE for the seal layer and to dispose COP adjacent thereto.

  The thickness of the heat-sealable resin layer is 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, 100 μm or less, preferably 75 μm or less, more preferably 50 μm or less. If the thickness of the heat-sealable resin layer (c) is 10 μm or more, a decrease in sealing strength can be suppressed, and contents can be prevented from leaking or flavor retention can be prevented, and 100 μm or less. If so, fluffing and film residue can hardly occur during peeling, and a good peeling appearance can be obtained, and it is economically preferable. Moreover, if the thickness of the gas barrier multilayer film as a whole is 200 μm or less, it is preferable that the whole film becomes too hard and pinholes are generated or handling becomes difficult.

Polyethylene-based resin comes on the seal layer side because the sealability and layer indirectness with COP are taken into consideration. The thickness of the polyethylene resin is not particularly limited, but is preferably set to 5 μm or more in consideration of sealing properties. Further, since it is not necessary to provide a thicker layer, the upper limit is preferably 50 μm, more preferably 30 μm or less. In view of the sealing strength, Ny is more preferable than the oxygen-absorbing EVOH as the resin adjacent to the polyethylene resin / COP / AD. This is because Ny is easier to adhere to the adhesive resin than EVOH, and the use of Ny increases the interlayer strength and increases the sealing strength. Ny used here is not particularly limited, but 6Ny can be used. However, since 6Ny has a high melting point of 224 ° C., the melting point is low to lower the extrusion temperature and the die temperature to prevent EVOH crosslinking. -66Ny can be used more suitably.

Further, the heat-sealable resin layer (c) includes an easy peel layer having cohesive failure, or may be formed of an easy peel layer. Here, having a cohesive fracture property means that, for example, when a deep-drawn package is produced using the gas barrier multilayer film of the present invention and the package is opened, the easy peel layer itself is broken and peeled off. It means that the easy peel layer after destruction remains on both the upper layer side (bottom material side) and the lower layer side (lid material side) of the easy peel layer. The resin constituting the easy peel layer is heat-sealable with the resin layer constituting the outer layer of the adherend, and has an easy peel strength of 1.96 N / 15 mm width to 11.8 N / 15 mm width, and gas barrier properties. There is no particular limitation as long as it takes a value smaller than the delamination strength of the other layer of the film. The easy peel strength is measured by heat sealing at 140 ° C. for 3 seconds and 3.1 kg / cm ² so that the sealing base material and the sealing layer of the gas barrier layer film overlap each other, and the sealing portion is sufficiently After cooling, cut a 15 mm wide test piece. The heat seal part is opened at 180 degrees with the center being held, both ends of the test piece are held on a tensile tester, a load is applied at a constant speed of 200 mm / min, and the peel strength is measured.

An easy peel layer can be comprised from the following resin A and resin B from which a kind differs, for example. That is, as resin A, linear low density polyethylene (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA) Ethylene-methacrylic acid copolymer (EMAA)
, Ethylene-methyl methacrylate copolymer (EMMA), ethylene-methyl acrylate copolymer (EMA), and at least one selected from the group consisting of these ionomers can be used. In particular, as the resin A, an ethylene-vinyl acetate copolymer (EVA) can be suitably used. On the other hand, as the resin B, polypropylene (PP) or polybutylene (PB) can be used. As the PP of the resin B, any of a random copolymer, a homopolymer, a block copolymer and the like can be used, and among these, a random copolymer can be preferably used.

The content of the resin A and the resin B is desirably 40% by mass or more, preferably 50% by mass or more of the resin A with respect to the mass of the entire easy peel layer from the viewpoint of sealing properties and unsealing properties. The upper limit is 80% by mass or less, preferably 75% by mass or less, and more preferably 60% by mass or less. On the other hand, the resin B is 20 to the mass of the entire easy peel layer.
It is desirable that the content is not less than mass%, preferably not less than 25 mass%, more preferably not less than 40 mass%, and the upper limit is not more than 60 mass%, preferably not more than 50 mass%. Resin A content is 4
By setting the content to 0% by mass or more (that is, the content of the resin B is 60% by mass or less), good heat sealability can be maintained. On the other hand, when the content of the resin A is 80% by mass or less (that is, the content of the resin B is 20% by mass or more), an appropriate easy peel strength can be obtained, and a good opening property can be obtained.

The easy peel strength of the easy peel layer is 1.96 N / 15 mm width (2
00 gf / 15 mm width) to 11.8 N / 15 mm width (1200 gf / 15 mm width) and less than the delamination strength of the other layers of the gas ariatic film.
The lower limit is preferably 2.94 N / 15 mm width or more, more preferably 3.92 N / 15 mm width or more, and further preferably 4 N / 15 mm width or more. On the other hand, the upper limit of the easy peel strength is preferably 9.8 N / 15 mm width or less, more preferably 7.84 N / 15 mm width or less. If the easy peel strength is 1.96 N / 15 mm width (200 gf / 15 mm width) or more, there is no risk of breaking the bag during use, and 11.8 N / 15 mm width (120
If it is 0 gf / 15 mm width) or less, good openability of the package can be maintained.

When the easy peel layer is included, the thickness of the easy peel layer is 3 μm or more, preferably 4 μm or more, more preferably 5 μm or more, from the viewpoint of film forming properties and appearance at the time of peeling, and the upper limit is 15 μm or less, preferably 12 μm. Hereinafter, it is more preferable that the thickness is 10 μm or less. By setting the thickness of the easy peel layer to 3 μm or more, stable film forming properties can be obtained. On the other hand, by setting the thickness of the easy peel layer to 15 μm or less, generation of fuzz and film residue can be suppressed when the package is opened, and a good peel appearance can be obtained.

[Outer layer or middle layer]
The outermost layer of the gas barrier multilayer film according to the present invention is preferably provided with a thermoplastic resin (a thermoplastic resin layer having a thermoplastic resin is provided). Examples of the thermoplastic resin include polyolefin resin, saponified ethylene-vinyl acetate copolymer, thermoplastic polyester resin, polyamide resin, and the like. As the polyolefin resin, for example, conventional low density polyethylene (LDPE), high density polyethylene (HDPE), or a blend of LDPE and HDPE can be used. The blend ratio can be appropriately determined for the purpose of imparting desired flexibility. For example, the blending ratio of LDPE and HDPE is 40 to 80:60 to 20, preferably 50 to 80:50 to 20, more preferably by mass ratio. Preferably it can be set to 60-80: 40-20. As the density increases, the rigidity, tensile strength, and heat resistance are improved, but impact strength, stress crack resistance, tensile strength, cold resistance, and transparency are lowered.
In addition, ethylene-α-olefin copolymers (eg, LLDPE, VLDPPE), ethylene / propylene copolymers, ionomer resins, EVA, ethylene / acrylic acid copolymers, ethylene -Methacrylic acid copolymer (EMAA) resin, modified polyolefin (for example, homopolymers or copolymers of olefins, unsaturated carboxylic acids such as maleic acid and fumaric acid, acid anhydrides or metals thereof A reaction product with a salt), a polypropylene (PP) resin, a cyclic polyolefin resin, and the like. By using PP resin, curling of the flange portion (portion sealed with the surface) of the pack product can be suppressed.

“Amorphous polyester resin” refers to a polyester resin in which 5 mol% or more of 1,4-cyclohexanedimethanol component is contained in 100 mol% of a polyhydric alcohol component. From the viewpoint of increasing the degree of amorphousness, it is desirable that the 1,4-cyclohexanedimethanol component is contained in an amount of 10 mol% or more, preferably 12 mol% or more, more preferably 15 mol% or more. On the other hand, if the 1,4-cyclohexanedimethanol component is too much, the impact strength of the film will decrease, so the upper limit is preferably 50 mol%, more preferably 47 mol% or less, and 45 mol. % Or less is more preferable.

  In the film of the present invention, in consideration of tear resistance, impact strength, heat resistance, etc., the ethylene terephthalate unit is 50 mol% or more, preferably 55 mol% or more in 100 mol% of the unit constituting the amorphous polyester resin. Further, it is preferable to select so as to be 60 mol% or more. Therefore, 50 mol% or more of terephthalic acid component (component formed from terephthalic acid or its ester) in 100 mol% of polyvalent carboxylic acid component, and 50 to 95 mol of ethylene glycol component in 100 mol% of polyhydric alcohol component %, Preferably 55 to 90 mol%, more preferably 60 to 88 mol%.

  Examples of the polyhydric alcohol for forming the polyhydric alcohol component include 1,3-propanediol, triethylene glycol, 1,4-butanediol in addition to the above-mentioned 1,4-cyclohexanedimethanol and ethylene glycol. 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9 -Alkylene glycols such as nonanediol, 1,10-decanediol, trimethylolpropane, glycerin, pentaerythritol, diethylene glycol, dimer diol, polyoxytetramethylene glycol, polyethylene glycol, bisphenol compounds or their derivatives Ido adducts such as can also be used in combination.

  In addition to the above-mentioned terephthalic acid and its esters, aromatic dicarboxylic acids, their ester-forming derivatives, aliphatic dicarboxylic acids, etc. can be used as the polyvalent carboxylic acids for forming the polyvalent carboxylic acid component. is there. Examples of the aromatic dicarboxylic acid include isophthalic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid. Moreover, derivatives of these aromatic dicarboxylic acids and terephthalic acids include derivatives such as dialkyl esters and diaryl esters. Examples of the aliphatic dicarboxylic acid include glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, succinic acid and the like, and an aliphatic dicarboxylic acid usually called dimer acid. Furthermore, an oxycarboxylic acid such as p-oxybenzoic acid, and a polyvalent carboxylic acid such as trimellitic anhydride and pyromellitic anhydride may be used in combination as necessary.

  In addition, although not polyhydric alcohols or polycarboxylic acids, lactones represented by ε-caprolactone may be used in part. Lactones are those that ring-open to become units having ester bonds at both ends, and a unit derived from one lactone can be considered to be a carboxylic acid component and an alcohol component. Therefore, when lactones are used, the amount of 1,4-cyclohexanedimethanol component and the amount of other polyhydric alcohol components are the total amount of polyhydric alcohol components of the film plus the unit amount derived from lactones. Calculated as 100 mol%. Also, when calculating the amount of each polycarboxylic acid component, the amount obtained by adding the unit amount derived from the lactone to the total polycarboxylic acid component amount of the film is 100 mol%.

  For example, a polyethylene terephthalate glycol resin (PETG) in which the diol component is composed of 1,4-cyclohexanedimethyl alcohol and ethylene glycol and the acid component of the dicarboxylic acid is terephthalic acid can be suitably used as the amorphous polyester resin of the present invention. .

  Although the thickness of an amorphous polyester resin layer is not specifically limited, It is preferable that it is the range of 10-50 micrometers, It is more preferable that it is 15-40 micrometers, It is further more preferable that it is 20-35 micrometers. When the thickness is less than 10 μm, curling occurs in the flange portion of the package, so that the appearance deteriorates. When the thickness exceeds 50 μm, the film becomes hard and the deep drawability deteriorates.

In the gas barrier multilayer film according to the present invention, the outermost layer and / or the intermediate layer preferably has at least one polyamide resin layer from the viewpoint of pinhole resistance. The polyamide resin constituting the polyamide resin layer is not particularly limited, but it is preferable to use a resin mainly composed of a lactam having a three-membered ring or more, a polymerizable ω-amino acid, a diamine and a dicarboxylic acid. . The polyamide resin may be a copolymer of a polyamide component and other components (for example, ω-amino acid, diamine and dicarboxylic acid as main components (50 mol% or more)). Is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more. Further, the polyamide resin may be a polymer blend. In that case, the polyamide component is preferably 70% by mass or more, and 75% by mass or more, based on the mass of the whole polymer blend (100% by mass). Is more preferable, and it is further more preferable that it is 80 mass% or more.

Examples of the lactam having 3 or more members include ε-caprolactam, ω-enantolactam, ω-laurolactam, α-pyrrolidone and the like. Examples of the polymerizable ω-amino acid include ω-aminocaproic acid, ω-aminoheptanoic acid, ω-aminononanoic acid, ω-aminoundecanoic acid, and ω-aminododecanoic acid. Examples of the diamine include tetramethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, and 2,2,4-tochimethyl hexamethylene diamine. 1,3 / 1, aliphatic amines such as 2,4,4-totimethylhexamethylenediamine,
, 4-Bis (aminomethyl) cyclohexane, isophoronediamine, piperazine, bis (
Examples include alicyclic diamines such as 4-aminocyclohexyl) methane and 2,2-bis- (4′-aminocyclohexyl) propane, and aromatic diamines such as metaxylylenediamine and paraxylylenediamine. Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonanedioic acid, decanedioic acid, undecanedioic acid, and dodecanedioic acid, hexahydroterephthalic acid, Alicyclic carboxylic acids such as hexahydroisophthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid (1,2-isomer, 1,3-isomer, 1,4-isomer, 1,5-isomer, 1
, 6-form, 1,7-form, 1,8-form, 2,3-form, 2,6-form, 2,7-form), and metal-isophthalsulfonic acid and other aromatic dicarboxylic acids. .

In the polyamide resin layer, the above-mentioned 3-membered or more lactam, polymerizable ω-amino acid, polyamide homopolymer or copolymer derived from diamine and dicarboxylic acid can be used alone or as a mixture. Specifically, for example, 4 nylon, 6 nylon, 7 nylon, 11 nylon, 12 nylon, 46 nylon, 66 nylon, 69 nylon, 610 nylon, 611 nylon, 6T nylon, 6I nylon, MX
D6 nylon, 6-66 nylon, 6-610 nylon, 6-611 nylon, 6-12
Nylon, 6-612 nylon, 6-6T nylon, 6-6I nylon, 6-66-61
0 nylon, 6-66-12 nylon, 6-66-612 nylon, 66-6T nylon, 66-6I nylon, 6T-6I nylon, 66-6T-6I nylon and the like. These polyamides may be homopolymers, copolymers, or mixtures of these resins.

For the polyamide resin layer, it is preferable to use a nylon resin from the viewpoint of moisture retention and pinhole resistance, and it is particularly preferable to use 6 nylon or 6-66 nylon. Further, two or more polyamide layers can be provided, and the pinhole resistance is improved as compared with the case of only one layer. In that case, each layer may be formed of a different type of nylon resin.

The lower limit of the thickness of the polyamide resin layer is preferably 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. The upper limit is preferably 200 μm or less, more preferably 170 μm or less, and even more preferably 150 μm or less. When the lower limit of the thickness of the polyamide resin layer is 10 μm or more, good moisture retention due to moisture absorption and good pinhole resistance can be obtained, and when the upper limit is 200 μm or less, the deep drawability is favorably maintained. Can do.

When the polyolefin resin is arranged in the outermost layer, as the polyolefin resin, for example, conventional low density polyethylene (LDPE), high density polyethylene (HDPE), or a blend of LDPE and HDPE can be used. The blend ratio can be appropriately determined for the purpose of imparting desired flexibility. For example, the blending ratio of LDPE and HDPE is 40 to 80:60 to 20, preferably 50 to 80:50 to 20, more preferably by mass ratio. Preferably it can be set to 60-80: 40-20. As the density increases, the rigidity, tensile strength, and heat resistance are improved, but impact strength, stress crack resistance, tensile strength, cold resistance, and transparency are lowered.
In addition, ethylene-α-olefin copolymers (eg, LLDPE, VLDPPE), ethylene / propylene copolymers, ionomer resins, EVA, ethylene / acrylic acid copolymers, ethylene -Methacrylic acid copolymer (EMAA) resin, modified polyolefin (for example, homopolymers or copolymers of olefins, unsaturated carboxylic acids such as maleic acid and fumaric acid, acid anhydrides or metals thereof A reaction product with a salt), a polypropylene (PP) resin, a cyclic polyolefin resin, and the like. By using PP resin, curling of the flange portion (portion sealed by the surface) of the pack product can be suppressed.

  The thickness of the polyolefin resin layer when the polyolefin resin is arranged as a layer is not particularly limited, but is preferably in the range of 10 to 150 μm, more preferably 20 to 100 μm, and more preferably 30 to 70 μm. More preferably. If the thickness is less than 10 μm, the curling property may be lowered in the case of PP resin, the cold resistance may be inferior in the case of PE resin, and if it exceeds 150 μm, the deep drawability may be deteriorated.

  When a thermoplastic polyester resin is disposed on the outermost layer, it is preferable to use an amorphous polyester resin as the thermoplastic polyester resin. “Amorphous polyester resin” refers to, for example, a polyester resin containing 5 mol% or more of 1,4-cyclohexanedimethanol component in 100 mol% of a polyhydric alcohol component. From the viewpoint of increasing the degree of amorphousness, it is desirable that the 1,4-cyclohexanedimethanol component is contained in an amount of 10 mol% or more, preferably 12 mol% or more, more preferably 15 mol% or more. On the other hand, if the 1,4-cyclohexanedimethanol component is too much, the impact strength of the film will decrease, so the upper limit is preferably 50 mol%, more preferably 47 mol% or less, and 45 mol. % Or less is more preferable.

  In the gas barrier multilayer film of the present invention, in consideration of tear resistance, impact strength, heat resistance, etc., ethylene terephthalate unit is 50 mol% or more, preferably 55 mol in 100 mol% constituting the amorphous polyester resin. It is preferable to select such that it is at least mol%, more preferably at least 60 mol%. Therefore, 50 mol% or more of terephthalic acid component (component formed from terephthalic acid or its ester) in 100 mol% of polyvalent carboxylic acid component, and 50 to 95 mol of ethylene glycol component in 100 mol% of polyhydric alcohol component %, Preferably 55 to 90 mol%, more preferably 60 to 88 mol%.

  Examples of the polyhydric alcohol for forming the polyhydric alcohol component include 1,3-propanediol, triethylene glycol, 1,4-butanediol in addition to the above-mentioned 1,4-cyclohexanedimethanol and ethylene glycol. 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9 -Alkylene glycols such as nonanediol, 1,10-decanediol, trimethylolpropane, glycerin, pentaerythritol, diethylene glycol, dimer diol, polyoxytetramethylene glycol, polyethylene glycol, bisphenol compounds or their derivatives Ido adducts such as can also be used in combination.

  In addition to the above-mentioned terephthalic acid and its esters, aromatic dicarboxylic acids, their ester-forming derivatives, aliphatic dicarboxylic acids, etc. can be used as the polyvalent carboxylic acids for forming the polyvalent carboxylic acid component. is there. Examples of the aromatic dicarboxylic acid include isophthalic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid. Moreover, derivatives of these aromatic dicarboxylic acids and terephthalic acids include derivatives such as dialkyl esters and diaryl esters. Examples of the aliphatic dicarboxylic acid include glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, succinic acid and the like, and an aliphatic dicarboxylic acid usually called dimer acid. Furthermore, an oxycarboxylic acid such as p-oxybenzoic acid, and a polyvalent carboxylic acid such as trimellitic anhydride and pyromellitic anhydride may be used in combination as necessary.

  In addition, although not polyhydric alcohols or polycarboxylic acids, lactones represented by ε-caprolactone may be used in part. Lactones are those that ring-open to become units having ester bonds at both ends, and a unit derived from one lactone can be considered to be a carboxylic acid component and an alcohol component. Therefore, when lactones are used, the amount of 1,4-cyclohexanedimethanol component and the amount of other polyhydric alcohol components are the total amount of polyhydric alcohol components of the film plus the unit amount derived from lactones. Calculated as 100 mol%. Also, when calculating the amount of each polycarboxylic acid component, the amount obtained by adding the unit amount derived from the lactone to the total polycarboxylic acid component amount of the film is 100 mol%.

  For example, a polyethylene terephthalate glycol resin (PETG) in which the diol component is composed of 1,4-cyclohexanedimethyl alcohol and ethylene glycol and the acid component of the dicarboxylic acid is terephthalic acid can be suitably used as the amorphous polyester resin of the present invention. .

  Although the thickness of an amorphous polyester resin layer is not specifically limited, It is preferable that it is the range of 10-50 micrometers, It is more preferable that it is 15-40 micrometers, It is further more preferable that it is 20-35 micrometers. When the thickness is less than 10 μm, curling occurs in the flange portion of the package, so that the appearance deteriorates. When the thickness exceeds 50 μm, the film becomes hard and the deep drawability deteriorates.

  When the ethylene-vinyl acetate copolymer saponified product is disposed in the outermost layer, the ethylene-vinyl acetate copolymer may be used as long as it has a hygroscopicity of an equilibrium water absorption of 3% or more at 20 ° C. and 100% RH. The details of the saponified product are not particularly limited. For example, the ethylene content of the saponified ethylene-vinyl acetate copolymer is 32 mol% or more, preferably 38 mol% from the viewpoint of film formation stability. It is above, and what is 47 mol% or less, Preferably it is 44 mol% or less can be used. When the ethylene-vinyl acetate copolymer saponified product layer is disposed, the thickness of the saponified product layer is not particularly limited, and may be, for example, 5 to 30 μm. If it is 5 μm or more, an improvement in oxygen barrier properties can be expected, and if it is 30 μm or more, moldability is lowered, which is not preferable. In addition, EVOH has good suitability for dry lamination without corona treatment, and thus enables strong adhesion to other substrates.

When heat resistance is required, it is preferable to use polypropylene (PP) resin, copolymerized polyester (Co-PET) resin, aliphatic nylon, aromatic nylon or the like as the outermost layer. Examples of preferred Co-PET contain isophthalic acid or cyclohexanedimethanol as a comonomer and have an IV value of 0. 7-0. There are about 8. These thermoplastic resins can be used alone or in combination of two or more.

It is preferable to use LLDPE, VLDPE, and Co-PET as the outermost layer because a heat-shrinkable multilayer film excellent in film forming property, transparency, boil resistance, puncture strength, and the like can be obtained. Further, when the ethylene-1-octene copolymer obtained by using a constrained geometric catalyst, preferably the ethylene-1-octene copolymer, is disposed in the outermost layer and / or the innermost layer, particularly the innermost layer, the slipperiness is good. Therefore, it is not necessary to add a slip agent (lubricant) or the amount added can be reduced. As a result, it is possible to suppress a decrease in transparency.

[Adhesive resin layer]
In the gas barrier film of the present invention, when a laminated film is formed by a coextrusion method, an adhesive resin layer can be interposed between the resin layers as necessary. As such an adhesive resin, a carbonyl (—CO—) group based on a carboxylic acid, a carboxylic acid anhydride, a carboxylate salt, a carboxylic acid amide, a carboxylic acid ester or the like is used as a main chain or a side chain, and 1 to 700 meq / A thermoplastic resin containing a concentration of 100 g resin, particularly 10 to 500 meq / 100 g resin, may be mentioned. Suitable examples of the adhesive resin include ethylene-acrylic acid copolymer, ion-crosslinked olefin copolymer, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, acrylic acid grafted polyolefin, ethylene-vinyl acetate copolymer, One or a combination of two or more types of resins such as copolyester and copolyamide can be used.

When the adhesive resin layer is provided, the thickness of the adhesive resin layer is 5 μm or more, preferably 8 μm or more, more preferably 10 μm or more from the viewpoints of workability, economy, and handleability, and the upper limit is not particularly limited. Is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. When the thickness of the adhesive layer is 5 μm or more, the delamination strength can be improved. On the other hand, if the adhesive layer is too thick, the total thickness of the bottom material becomes thick and the manufacturing cost increases, so the upper limit is preferably 25 μm or less.

The gas barrier film of the present invention can be provided with a printing layer as necessary. The thickness of the printing layer is not particularly limited, and can be formed in the range of 0.5 μm to 10 μm, preferably 1 μm to 5 μm. The print layer is not limited to a layer representing a pattern, characters, or the like, and may be a colorless and transparent layer made of only a medium or a resin (vehicle). Also, it can be a colorless and transparent layer consisting only of medium or resin (vehicle), and a layer consisting of two layers representing a pattern, characters, etc. If necessary, such as antistatic, ultraviolet absorption, ultraviolet shielding etc. A layer having a function may be included.

The printing layer can be formed by a known method such as gravure printing, offset printing, screen printing, etc., but a volatile drying type ink having a quick drying property can be used, and high speed printing can be performed by a winding type rotary printing press. From such a viewpoint, it is preferable to form by gravure printing. To illustrate a preferred printing method, after the inner layer and the intermediate layer of the bottom material and the lid material are respectively produced by the coextrusion method, printing is performed on the previously prepared outer layer by gravure printing, and then the printing layer is formed by the dry laminating method. By laminating so as to face the intermediate layer (back printing), a laminated film having a printed layer can be produced, and a bottom material or a lid material excellent in appearance can be obtained. When used as a lid for a gas pack, it is generally difficult to seal a coextruded film alone in terms of heat resistance, and it is necessary to bond it with a biaxially stretched film in order to stabilize the peeling. Examples of the biaxially stretched film include a stretched nylon film (hereinafter referred to as “ONy”), a stretched polypropylene film (hereinafter referred to as “OPP”), and a polyethylene terephthalate film (hereinafter referred to as “PET”). From the viewpoint of stability and printing pitch stability, those obtained by bonding a PET film and an ONy film are preferable. In particular, it is preferable to select PET when emphasizing the printing pitch accuracy, and to select ON y when emphasizing the tension of the lid material after boiling the packed product. Further, as the bottom material for gas pack deep drawing, PP, amorphous PET, polycarbonate (hereinafter referred to as “PC”), polystyrene (hereinafter referred to as “PS”), high impact polystyrene (hereinafter referred to as “PS”). It can also be used by bonding together.

  In the gas barrier multilayer film of the present invention, a pinhole-resistant resin layer can be provided outside the oxygen-absorbing resin layer as necessary. These thicknesses are not particularly limited, and can be formed in the range of 5 to 40 μm, preferably in the range of 10 to 30 μm. A biaxially stretched polypropylene film or a biaxially stretched polyethylene terephthalate film is particularly preferably used as the moisture resistant resin layer, and a biaxially stretched polycaproamide (NY6) film is particularly preferably used as the pinhole resistant resin layer. These resin layers can be laminated by dry lamination or extrusion lamination. Moreover, PET, PP, and NY can be laminated by a co-pushing method.

<Method for producing gas barrier multilayer film>
In the gas barrier multilayer film of the present invention, the oxygen-absorbing resin layer (a) and the cyclic polyolefin resin layer (b) can be formed separately and then bonded together using a dry lamination method, an extrusion lamination method, or the like. . From the viewpoint of preventing wasteful oxidation of the oxygen-absorbing resin during film formation and reducing the film formation cost, it is preferable to produce the film by coextrusion. Similarly, when an adhesive resin layer or another resin layer is provided, it is preferably produced by a coextrusion method.

  When a multilayer film is produced by the coextrusion method, extrusion molding may be performed in the same manner as described above except that a multilayer multiple die is used using, for example, the number of extruders corresponding to the type of resin. Furthermore, for the production of a multilayer film or a multilayer sheet, an extrusion coating method or sandwich lamination can be used, and the multilayer film or sheet can also be produced by dry lamination of a film formed in advance.

[Packaging]
[Deep-drawing packaging base and deep-drawing packaging]
The gas barrier multilayer film of the present invention can be formed into a deep drawn package having a size and shape corresponding to the contents using a deep draw packaging machine. In particular, when the film of the present invention is used as a bottom material for packaging, a deep drawn package excellent in gloss, transparency, and pinhole resistance can be obtained. Further, the deep-drawn package of the present invention can be produced by bonding the bottom material and the lid material by an adhesive means such as heat sealing.

Specifically, for example, after the film of the present invention is formed into a desired shape and size with a deep drawing mold to form a bottom material (film supply process and film forming process), contents such as sliced ham are contained therein. Fill the product (content filling process), seal with a lid material film (cover material film supply process and sealing process) from above, vacuum package (vacuum packaging process), cool (cooling process), cut By doing (cutting process), a deep drawing package can be produced. I can.
The deep-drawn package of the present invention may be constituted by forming one of the bottom material or the cover material with the gas barrier multilayer film according to the present invention and the other with a film other than the present invention. For example, as a film other than the present invention constituting the cover material, a laminate of a stretched polypropylene resin layer, a transparent vapor-deposited polyethylene terephthalate resin and a linear low density polyethylene (LLDPE) layer, or a coextrusion with a stretched polyethylene terephthalate resin A laminate of a film (a film containing EVOH and Ny and using LLDPE as a seal layer) can be used.

Further, a PET film can be further laminated on the outer layer side of the composite film of the present invention to form a lid material. In this case, when printing is required, the printing pitch is stabilized (the heat-fixed PET film does not stretch), and the back side can be printed so that the printing surface does not come into contact with food, etc. There is an advantage such as that it can be imparted.

  The gas barrier package of the present invention can be produced by a method known per se, except that the above-described gas barrier multilayer film is used. For example, a film, a sheet, or a tube is formed by melting and kneading a resin constituting each layer with an extruder and then extruding the resin into a predetermined shape through a T-die, a circular die (ring die) or the like.

  A packaging material such as a film can be used as a packaging bag of various forms, and the bag can be produced by a known bag-making method, such as ordinary pouches with three- or four-side seals, pouches with gussets. Examples include soft packaging applications such as, but not limited to, examples such as standing pouches and pillow packaging bags.

  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 foods, 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.

<Oxygen absorbing resin>
A 95: 5 mixture of 32 mol% ethylene-vinyl acetate copolymer saponified pellets and cobalt stearate was extruded in 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 master batch. While extruding 32 mol% ethylene-vinyl acetate copolymer saponified pellets with a twin screw extruder under a nitrogen atmosphere, polybutadiene (epoxy-functionalized polybutadiene-Elf-Atochem Poly BD 600 / Poly BD 605E) was brought to a weight ratio of 5%. Added as follows. The extruded strand was quenched in a water bath, then pelletized and dried to obtain oxygen-absorbing resin pellets.

<Production of composite film>
As Examples 1-8 and Comparative Examples 1-7, deep-drawn packaging films having the following configurations and thicknesses were produced by a coextrusion method.
In addition, resin used as each layer in an Example and a comparative example is as follows.

Outer layer (thermoplastic resin layer)
Polyamide resin = Novamid (6-NY) manufactured by Mitsubishi Engineering Plastics
Polyester resin = Eastman Chemical Co., Ltd. PETG6763
Polyethylene resin = Nippon Polyethylene Novatec (LDPE, LLDPE, HD PE, EVA),
Polypropylene resin = Novatec PP manufactured by Nippon Polypolopylene Co., Ltd.

Intermediate layer adhesive resin layer = “Admer (registered trademark) NF556” (manufactured by Mitsui Chemicals),
Polyamide resin layer = “NOVAMID (registered trademark)” (6-66 copolymer nylon (66 nylon content 15%)) (Mitsubishi Engineering Plastics)

Oxygen-absorbing resin layer Mixed resin in which the oxygen-absorbing resin pellets are mixed so as to contain 100 ppm of cobalt master batch as cobalt

Cyclic polyolefin resin layer COC layer "TOPAS 8007 (registered trademark)" (manufactured by Polyplastics)

Heat-sealable resin layer Heat-sealable resin layer A: EVA + PB-1 blend product NOVATEC made by Mitsubishi Chemical Corporation
(Registered trademark) EVA + Sun Aroma Co., Ltd. Basel Polybutene (PB-1) at 60:40
blend

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

(Example 1) Composition of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (20 μm) / cyclic polyolefin resin layer (103 μm) / heat-sealable resin layer (7 μm) [total Thickness 200μm]

(Example 2) Composition of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (20 μm) / adhesive resin layer (20 μm) / cyclic polyolefin resin layer (113 μm) / heat-sealable resin layer (7 μm) [total Thickness 200μm]

(Example 3) Composition of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (20 μm) / adhesive resin layer (20 μm) / layer (113 μm) blended with cyclic polyolefin resin and LLDPE at 80: 20 / heat Sealing resin layer (7μm) [total thickness 200μm]

(Example 4) Constitution of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (70 μm) / cyclic polyolefin resin layer (53 μm) / heat-sealable resin layer (7 μm) [total Thickness 200μm]

(Example 5) Composition of each layer Polyester resin layer (PETG layer) (30 μm) / adhesive resin layer (5 μm) / polyamide resin layer (30 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (5 μm) ) / Cyclic polyolefin resin layer (93 μm) / Heat sealable resin layer (7 μm) [total thickness 200 μm]

(Example 6) Composition of each layer Polyethylene resin layer (PE layer) (50 μm) / adhesive resin layer (10 μm) / polyamide resin layer (30 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (10 μm) ) / Cyclic polyolefin resin layer (63 μm) / Heat sealable resin layer (7 μm) [total thickness 200 μm]

(Example 7) Composition of each layer Oxygen-absorbing resin layer (30 μm) / polyamide resin layer (10 μm) / adhesive resin layer (5 μm) / cyclic polyolefin resin layer (50 μm) / heat-sealable resin layer (5 μm) [total Thickness 100μm]

(Example 8) Composition of each layer Polypropylene resin layer (50 μm) / adhesive resin layer (10 μm) / polyamide resin layer (30 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (10 μm) / cyclic polyolefin Resin layer (63 μm) / heat-sealable resin layer (7 μm) [total thickness 200 μm]

(Example 9) Composition of each layer Oxygen-absorbing resin layer (30 μm) / adhesive resin layer (20 μm) / cyclic polyolefin resin layer (103 μm) / heat-sealable resin layer (7 μm) [total thickness 160 μm]

(Example 10) As a constituent oxygen-absorbing resin of each layer, “Quintia EV series (registered trademark) EV3210” = (saponified ethylene-vinyl acetate copolymer, ethylene content 32 mol% type) (Nippon Zeon Corporation) The same configuration as in Example 1 except that the product manufactured by the company was used.

(Comparative Example 1) Constitution of each layer Polyamide resin layer (40 μm) / Oxygen absorbing resin layer (10 μm) / Adhesive resin layer (20 μm) / Cyclic polyolefin resin layer (133 μm) / Heat sealable resin layer (7 μm) [Total Thickness 200μm]

(Comparative Example 2) Composition of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (70 μm) / cyclic polyolefin resin layer (33 μm) / heat-sealable resin layer (7 μm) [total Thickness 200μm]

(Comparative Example 3) Constitution of each layer Polyamide resin layer (60 μm) / Oxygen absorbing resin layer (30 μm) / EVOH resin layer (10 μm) / Adhesive resin layer (20 μm) / Linear low density polyethylene resin layer (73 μm) ) / Heat-sealable resin layer (7 μm) [total thickness 200 μm]

(Comparative example 4) Composition of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (20 μm) / high-density polyethylene resin layer (103 μm) / heat-sealable resin layer (7 μm) [ Total thickness 200μm]

(Comparative Example 5) Constitution of each layer Polyamide resin layer (40 μm) / oxygen-absorbing resin layer (30 μm) / adhesive resin layer (20 μm) / polypropylene resin layer (103 μm) / heat-sealable resin layer (7 μm) [total thickness 200μm]

(Reference Example 1) Structure of each layer In Example 1, the deep drawing amount is 40 mm.

[Evaluation methods]
<Oxygen barrier test>
(Test 1. Leucomethylene Blue test)
For the films of Examples 1 to 9, Comparative Examples 1 and 2, and Reference Example 1, using a deep drawing packaging machine (FV-6300, manufactured by Omori Machine Industry Co., Ltd.), a heating temperature of 90 ° C. and a diameter of 95 mm, Two types of molded articles (containers) having a drawing depth of 10 mm and 30 mm were formed (molding heating time was 3 seconds, molding time 1.8 seconds, vacuum time 2 seconds). The resulting molded product (container) is filled with a special solution (leucomethylene blue solution) that changes its color from white to blue when oxygen enters, and vacuum-packed using an aluminum film (aluminum foil 30 μm / PE 50 μm) on the lid The inside of the container was evacuated with a machine and completely sealed to prepare an evaluation sample. The filling amount of the leucomethylene blue solution into the evaluation sample is 70 cc at a squeezing depth of 10 mm and 210 cc at 30 mm.
Thereafter, it was stored under conditions of 30 ° C. and 80% RH, and after 4 weeks, the degree of discoloration of the leucomethylene blue solution was observed (non-high temperature sterilization treatment). In addition, after filling with a special solution (leucomethylene blue solution), it was subjected to high-temperature sterilization at 95 ° C. for 30 minutes and stored at 30 ° C. and 80% RH, and after 4 weeks, the degree of discoloration of the leucomethylene blue solution was observed. (After high temperature sterilization). The evaluation methods were as follows: (1) both judged visually and (2) evaluated from the transmittance peak.

Ｋ；反応速度 Ａ；反応定数 e ;自然対数の底
Ｅ；見かけの活性化エネルギ Ｒ；ガス定数 Ｔ；絶対温度
を適用した。
また、湿度については、絶対湿度に比例して劣化が促進すると考え、
２３℃５０％ＲＨ ２０g×０．５＝１０g
３０℃８０％ＲＨ ３０．４g×０．８＝２４．３２ｇ
２４．３２ｇ÷１０＝２．４３２倍
温度と湿度の両方の促進性を考えると、温度は２倍、湿度は２．４３２倍となり
これを掛け合わせると ２ × ２．４３２ ＝４．８６４倍
すなわち、３０℃８０％ＲＨで４週間試験したものは、常温（２０度６０％）の２１週間に相当するものと考えられるが、実際に促進試験と常温での放置試験の両方を行ってその相関性と促進性を把握し、常温で２５週以上（１８０日間）に相当することを確認した。

（１） 目視評価
○：メチレンブルー溶液がわずかに青色に変化又は変色なし、
△：メチレンブルー溶液が若干青色に変化
×：メチレンブルー溶液が青色に変化
（２） 透過率のピークでの評価
ＳＨＩＭＡＺＵ ＵＶ−２４５０分光光度計を用いて吸収スペクトルを測定し、ロイコメチレンブルーの固有波長である６６５nmにおける透過率のピークから評価した。尚、ロコメチレンブルーの固有波長での透過率は、白色（酸素の容器への進入が少ないか又は無い状態を示す）である場合には値が高く、青色（酸素の容器への進入がある状態）である場合には値は低く評価される。

（分光光度測定結果−高温殺菌処理済み）

In addition, the said test is an accelerated test on the assumption that the test performed in 180 days is performed in 4 weeks.
In other words, for temperature, the Arrhenius equation

K; reaction rate A; reaction constant e; base of natural logarithm E; apparent activation energy R; gas constant T; absolute temperature was applied.
In addition, regarding humidity, we think that deterioration accelerates in proportion to absolute humidity,
23 ° C. 50% RH 20 g × 0.5 = 10 g
30 ° C. 80% RH 30.4 g × 0.8 = 24.32 g
24.32g ÷ 10 = 2.432 times Considering the acceleration of both temperature and humidity, the temperature is 2 times and the humidity is 2.432 times, and when multiplied, 2 × 2.432 = 4.864 times A test conducted at 30 ° C and 80% RH for 4 weeks is considered to be equivalent to 21 weeks at room temperature (20 ° C and 60%). It was confirmed that it corresponds to 25 weeks or more (180 days) at room temperature.

(1) Visual evaluation ○: Methylene blue solution slightly changed to blue or no discoloration,
Δ: Methylene blue solution turns slightly blue ×: Methylene blue solution turns blue (2) Evaluation at transmittance peak The absorption spectrum is measured using a SHIMAZU UV-2450 spectrophotometer and is the intrinsic wavelength of leucomethylene blue Evaluation was made from the transmittance peak at 665 nm. In addition, the transmittance at the intrinsic wavelength of locomethylene blue is high when it is white (indicating a state where there is little or no oxygen entering the container) and blue (a state where oxygen enters the container). ) Is underestimated.

(Spectrophotometric measurement result-high temperature sterilization)

(Test 2. Oxygen permeability measurement)
The heat seal layer of the film (before deep drawing) was used as the inside, and the surroundings were heat sealed, and 5 bags of 30 cm in length and 20 cm in width with about 300 ml of nitrogen inside were made. This bag was stored in an environment of 23 ° C. and 50% RH. On the 180th day, the 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 average was obtained as the oxygen transmission rate after 180 days. The gas permeability resin (ethylene content 38 mol% type) having a thickness of 10 μm has an oxygen permeability of 0.16 fm / s · Pa under conditions of 23 ° C. and 50% RH, and is in a standard state in air (23 ° C. for 23 days). The oxygen transmission rate at 50% RH was 0.61 fm / s · Pa.

<Odor evaluation>
(Test 3. Sensory test)
Using the deep drawing packaging machine (FV-6300, manufactured by Omori Machine Industry Co., Ltd.), the above film was formed into two types with a heating temperature of 90 ° C. and a diameter of 95 mmφ and a drawing depth of 10 and 30 mm. 3 seconds, molding time 1.8 seconds, vacuum time 2 seconds). The obtained molded article was filled with paper removal cotton soaked with 5 cc of water, and the lid was completely sealed with an aluminum film. Thereafter, it was left for 14 days under conditions of 23 ° C. and 50% RH. Thereafter, five panelists conducted a sensory evaluation of the odor of the head space gas of the packed product.
○: Almost unpleasant odor △: Slightly unpleasant odor ×: Strongly unpleasant odor

  The evaluation results are shown in Table 1.

  From Table 1, the gas barrier multilayer film within the scope of the present invention can stably maintain a high oxygen gas barrier property for a long period of time even after deep drawing, and if a package is produced, a good gas barrier performance is maintained for a long period of time. Films that could be sustained and maintained good moldability and pinhole resistance were obtained (Examples 1 to 9). On the other hand, when the cyclic polyolefin resin layer was thin (Comparative Example 2), an unpleasant odor was generated after deep drawing, and stable barrier properties after heat sterilization were not obtained. When the oxygen-absorbing resin layer was thin (Comparative Example 1), good oxygen barrier properties could not be obtained at the time before heat sterilization. When an EVOH resin having a high gas barrier property is disposed inside the oxygen-absorbing resin layer (Comparative Example 3), the gas barrier property of the EVOH resin is lowered during the heat sterilization, and thus the color is changed to blue after the heat sterilization and is stable. Barrier properties were not obtained. When high density polyethylene or polypropylene resin is arranged instead of the cyclic polyolefin resin (Comparative Examples 4 and 5), the water vapor barrier property at the time of heat sterilization treatment is lacking, and the stable barrier property after heat sterilization cannot be obtained. It was.

When the deep drawing amount was 40 mm (Reference Example 1), oxygen permeation from the thinnest corner portion after molding was observed and the oxygen barrier property was lacking. Thus, according to the present invention, even after heat sterilization with hot water or steam, the permeation amount of oxygen is suppressed to almost zero, and the packaging material is high over a long period even when stored under high temperature and high humidity. Transparency, moldability, pinhole resistance, moldability, and rigidity that can maintain oxygen gas barrier properties and suppress the odor that can be generated when the oxygen-absorbing resin absorbs oxygen to the contents side It turns out that the outstanding gas-barrier multilayer film and package can be provided.

Claims (9)

A gas barrier film comprising a multilayer film comprising at least three layers, the oxygen-absorbing resin layer (a), a cyclic polyolefin layer (b) on the inner side, and a heat-sealable resin (c) on the innermost layer. A gas barrier multilayer film having an oxygen permeability of 0.01 fm / s · Pa (1 ml / m ² · day · MPa) or less at 23 ° C. and 50% RH for at least 180 days. The gas barrier according to claim 1, wherein the oxygen-absorbing resin (a) is a composition containing an ethylene-vinyl acetate copolymer saponified product or a polyamide-based resin as a main component, and further containing an oxidizable resin and a transition metal-based catalyst. Multilayer film. 3. The gas barrier property according to claim 1, wherein the cyclic polyolefin layer (b) has a glass transition temperature (T g) of 60 ° C. to 140 ° C. or less and a thickness of 30 μm or more. Multilayer film. The gas barrier multilayer film according to claim 1, further comprising at least one polyamide layer on the multilayer film. The gas barrier multilayer film according to claim 1, further comprising at least one adhesive resin layer on the multilayer film. The gas barrier multilayer film according to claim 1, further comprising at least one polyolefin layer in the multilayer film. The gas barrier property according to any one of claims 1 to 6, wherein the heat seal resin layer has an easy peel strength of 0.8 N / 15 mm width or more and 11.8 N / 15 mm width or less at 25 ° C. Multilayer film. The gas barrier multilayer film according to any one of claims 1 to 7, wherein the thickness of the oxygen-absorbing resin layer (a) is from 15 µm to 50 µm, and the thickness of the cyclic polyolefin resin layer (b) is from 40 µm to 100 µm. . A bottom material for a deep-drawn package body formed of the gas barrier multilayer film according to claim 1.

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