JP2018020513A - Co-extrusion non-stretched film for tray molding, composite sheet, and tray - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-stretched co-extrusion film having excellent oxygen barrier and heat sealing properties and suitable for tray molding, a composite sheet with the non-stretched co-extrusion film put on a resin sheet, and a molded tray.SOLUTION: The present invention provides a co-extrusion non-stretched film that is put on a resin sheet of 300 μm or more in thickness for tray molding. The co-extrusion non-stretched film has, in order from the side of an article stored in the tray, a heat seal layer predominantly composed of polyolefin resin, a gas barrier layer, an oxygen-absorbing layer, and an outer layer predominantly composed of polypropylene resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-stretched coextruded film suitable for tray molding and a composite sheet laminated with a resin sheet, which has gas barrier properties and heat sealability, can be printed, and has microwave oven heat resistance.

In recent years, the food industry has become active in reducing food waste loss as a means of reducing environmental impact, reducing costs, and effectively using resources.
Therefore, in terms of packaging materials, we have contributed to these efforts by providing packaging materials and packaging methods that extend the shelf life of foods. For example, oxygen inflow and miscellaneous bacterial growth that cause food degradation are suppressed. The means to do is utilized.
Heat sterilization in sealed packaging and sealed packaging in an aseptic room are performed as methods for suppressing oxygen inflow and miscellaneous bacteria growth, and vacuum packaging and gas replacement packaging with gas barrier packaging materials can be used to further enhance the effect. Is used.

  In particular, foods with a short shelf life, such as meat, fresh fish, and side dishes, have been mainly used in the past by wrapping a wrap film around a resin tray that does not have a gas barrier property or by simply fitting a lid on the resin tray. These packaged foods have a short shelf life and a large amount of sales, so reducing waste loss is an urgent issue.

  On the other hand, in food trays that handle these fresh foods, a design that expresses a sense of quality and cleanliness is emphasized, and printed polystyrene resin sheets and full-layer expanded polystyrene resin sheets are used. However, the polystyrene resin sheet cannot be deep-drawn because of its low heat-resistant rigidity, and cannot be used for a gas replacement package (gas pack) that is filled with an inert gas and sealed.

Therefore, a gas replacement package using a tray and a lid made of a gas barrier material has attracted attention.
As an example of the tray, Patent Document 1 discloses a technique in which a plastic film having a heat-fusible resin layer, a gas barrier layer, and an easy-peeling seal layer and a polypropylene resin sheet having a thickness of several hundreds of μm are heat-sealed and laminated. Is disclosed.

However, since the film has poor flatness, roll winding defects and avatars are likely to occur, resulting in defects such as missing prints and misalignments.
As a result, the decoration of food trays cannot be printed on film, so there is no other way than to do it by coloring sheets, and the tray design that greatly influences consumers' purchasing awareness has become limited. ing.
In addition, since the types of sheets to be heat-sealed are limited to polypropylene resin sheets and high-density polyethylene resin sheets, it can be applied only to solid color plain trays such as jelly cups and cooked rice containers, and has a large amount of production and sales. It cannot be used for trays for fresh food or side dishes.

  In Patent Document 2, a film having an ethylene-vinyl alcohol copolymer resin (EVOH) layer as an outer layer and a heat-sealable layer as an inner layer is formed for deep drawing and gas pack packaging, and has a thickness of several hundred μm. A technique for laminating an amorphous polyethylene terephthalate resin sheet with a dry laminate is disclosed.

  However, these films are suitable for laminating, but have a lot of curl in terms of layer structure, so that printing is easily shifted. Also. Although the composite sheet with the polyethylene terephthalate resin sheet is excellent in transparency, the heat resistance is low, and the thickness is increased in order to maintain rigidity against the weight of meat, sugar beet, etc., and the manufacturing cost is increased.

In addition, as a film having gas barrier properties and heat sealability and capable of printing, and suitable for tray molding, Patent Document 3 discloses {polypropylene resin + low density polyethylene resin} / {saponified ethylene-vinyl acetate copolymer or Co-extruded films having a layer configuration of metaxylene adipamide nylon resin} / polyolefin resin are disclosed, but in these films, the oxygen permeability is about ^{2 to 5} cc / m ² / day / atm. There is a demand for a tray container having a higher oxygen barrier property for extending the shelf life.

JP 2000-190435 A Japanese Patent Laid-Open No. 8-288181 Japanese Patent Application Laid-Open No. 2006-064643

  The present invention is intended to solve the above-mentioned problems. The object of the present invention is a composite in which an unstretched coextruded film suitable for tray molding and a resin sheet are laminated while having a good oxygen barrier property and heat sealability. Lies in providing sheets and molded trays.

  As a result of intensive studies, the present inventor is a coextrusion non-stretched film for stacking on a resin sheet having a thickness of 300 μm or more to form a tray, and the polyolefin resin is a main component in order from the side of the tray. The present inventors have found that this problem can be solved by a coextruded unstretched film having a heat seal layer, a gas barrier layer, an oxygen absorbing layer, and an outer layer mainly composed of a polypropylene resin, and completed the present invention.

According to the co-extrusion non-stretched film of the present invention, it has a good oxygen barrier property and heat sealability without impairing the flavor and fragrance of the contained material, and gives a decorative property to the tray because it can be printed. can do. In addition, the composite sheet of the present invention can form a tray with a good sealing property with the lid material, a vacuum pack and a packaging suitability of an inert gas pack. Extension and reduction of food and packaging waste loss were made possible.
Furthermore, since the sheet | seat to laminate | stack can be selected from various resin sheets, preparation of the tray which also has microwave oven heat resistance was attained.

Is a package in which a tray composed of a composite sheet (3) obtained by laminating a coextrusion non-stretched film (1), a composite sheet, and (2), and a lid (4) are closely attached at the peripheral edge thereof. It is an example of sectional drawing.

The present invention will be described below.
The coextruded unstretched film of the present invention (hereinafter simply referred to as “the film of the present invention”) is laminated with a resin sheet and used for tray molding. In tray molding, the coextrusion non-stretched film is located on the container side, and the resin sheet is located on the outside air side. That is, the outer layer of the film of the present invention is located on the resin sheet side, and the heat seal layer is located on the container side. Accordingly, the layer structure of the composite sheet of the present invention is in the order of coextruded film {heat seal layer / odor barrier layer / oxygen absorbing layer / outer layer} / resin sheet from the container side.

  In this specification, “main component” and “configured as main component” are intended to allow other components to be included within the range that does not impede the action and effect of the resin that constitutes each layer. It is. Further, this term does not limit the specific content, but occupies 50% by mass or more and 100% by mass or less, preferably 60% by mass or more, more preferably 80% by mass or more of the total components of each layer. Means that.

<Outer layer>
The outer layer of the film of the present invention is composed mainly of polypropylene resin.
The type of the polypropylene resin is not particularly limited, but a propylene-ethylene copolymer or a propylene homopolymer is preferable from the viewpoint of transparency and dimensional stability.

The outer layer preferably contains 5% by mass or more and 20% by mass or less of a low density polyethylene resin, the lower limit is more preferably 10% by mass or more, and the upper limit is more preferably 15% by mass or less.
When the content is 5% by mass or more, an increase in melt tension on the surface of the film due to resin mixing increases the film thickness uniformity and avatar suppression. On the other hand, if it is 20% by weight or less, the cohesive force in the layer increases and the interlayer adhesion strength becomes good.

  The type of low-density polyethylene resin used for the outer layer is not particularly limited, but it is effective to be a resin having a high melt tension for film thickness uniformity and defect suppression. A high-pressure low-density polyethylene resin having a large amount is preferable.

When the outer layer of the present invention is formed by mixing a polypropylene resin and a low density polyethylene resin, fine irregularities can be formed on the surface of the outer layer due to the incompatibility of both resins, and the printing ink and various coating agents are formed on the film surface by the irregularities. It adheres effectively and has good printing, coating and laminating suitability.
By performing the corona discharge treatment when the resin having a fine irregular surface is formed and the resin has a high reactivity immediately after film formation, the suitability for printing, coating and laminating is further improved.
Fine irregularities on the outer layer surface can be observed and measured with an optical microscope or a surface roughness meter.

  Moreover, since the tension | tensile_strength at the time of film forming is raised by the mixing effect of a low density polyethylene resin compared with the case where it forms only with a polypropylene resin, it becomes possible to produce a thin film with uniform thickness. Further, it is possible to prevent the “avatar” phenomenon caused by the slow cooling crystallization partially progressing due to the undulation of the film and whitening.

For this reason, the film of the present invention is less likely to cause bumps and wrinkles when rolled, so that it is highly suitable for post-processing printing and lamination.
Therefore, the film of the present invention can be laminated with various resin sheets after performing extrusion lamination directly on the surface of the outer layer, or after printing on the surface of the outer layer without missing or misalignment.
In addition, a well-known technique can be used for the method of printing and coating to the outer layer surface of a film.

  The outer layer of the film of the present invention may be composed of two or more layers. In that case, the layer mainly composed of the above-described polypropylene resin is arranged on the surface layer of the film, that is, on the side of the resin sheet to be laminated, and is adjacent thereto. It is preferable to dispose a polypropylene resin layer or a polyethylene resin layer. In particular, when the same type of resin as the polypropylene resin used for the surface layer is used, the interlayer affinity is good and rigidity can be imparted to the film, which is effective in improving the workability of the film.

The thickness of the outer layer is preferably 8 μm or more and 30 μm or less as the total thickness of the outer layer, whether it is a single layer or two or more layers. The lower limit of the thickness is more preferably 10 μm or more, and further preferably 12 μm or more. The upper limit is more preferably 25 μm or less, and further preferably 20 μm or less.
If the thickness of the outer layer is 8 μm or more, stiffness (rigidity) of the entire film and processing suitability for printing and laminating are imparted, and if it is 30 μm or less, wrinkle generation in the printing and laminating steps can be suppressed.
Moreover, since the thickness of the outer layer affects the curl of the film depending on the ratio with the thickness of the inner layer, it is preferably 60% or more and 130% or less with respect to the thickness of the inner layer.

<Oxygen absorption layer>
In the film of the present invention, an oxygen absorbing layer is disposed at a layer position between the outer layer and the heat seal layer.
It is preferable that the oxygen permeability of the film is ² cc / (m ² · day · atm) or less, preferably 1 cc / (m ² · day · atm) from the viewpoint of suppressing oxygen deterioration of the contained material by providing the oxygen absorbing layer. It is more preferable to set the following.

  For the configuration of the oxygen absorbing layer, a resin composition containing an oxidizable resin (S) and a transition metal catalyst (M) is preferably used. From the standpoint 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. For example, Nippon Zeon Quintia (registered trademark) can be exemplified.

  The oxidizable resin (S) is a resin that is oxidized by oxygen in the air by the action of the transition metal catalyst (M). Specifically, (i) a resin containing a carbon side chain, (ii) xylylene Group-containing polyamide resins, (iii) ethylenically unsaturated group-containing polymers, (iv) polyether-containing polymers, and the like. Further, the oxidizable resin (S) is a transition metal catalyst (M) in a resin mainly composed of a general thermoplastic resin, for example, a polyamide resin, a polyester resin, a polyolefin resin, or the like, that is, in a base resin. It is also preferable to be used as an oxygen-absorbing resin composition by being mixed and dispersed together.

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

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

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

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

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

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

Specific examples of the polyene polymer include polybutadiene (BR), polyisoprene (IR), butyl rubber (IIB), natural rubber, nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), chloroprene rubber ( CR), ethylene-propylene-diene rubber (EPDM) and the like, but are not limited to these examples.
The carbon atom adjacent to the carbon-carbon double bond in the polyene polymer is active 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 of only the oxidizable resin (S) and the transition metal catalyst (M), but is mixed and dispersed with other thermoplastic resins as main components. It is preferable. By adjusting and using the amount of mixing / dispersing, the oxygen absorption capacity as the oxygen-absorbing resin layer (a) can be adjusted, and the influence of deterioration of physical properties after oxygen absorption can be reduced. When mixed and dispersed in another thermoplastic resin, the oxidizable resin (S) is 1 to 20% by mass, preferably 3 to 10% by mass, based on the total amount of the oxygen-absorbing resin composition. It is preferable to adjust so that it exists. 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 acid-modified polyene polymer is favorably dispersed in another resin (matrix resin) and oxygen is smoothly absorbed. Further, a hydroxyl group-modified polyene polymer having a hydroxyl group at the terminal can also be used favorably.

  Specific examples of functional oxidizable polydienes as suitable oxygen scavengers are epoxy functionalized polybutadiene (1,4 and / or 1,2), maleic anhydride grafted or copolymerized polybutadiene (1,1). 4 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 polystyrene oxide.

  As another thermoplastic resin that is a main component in the oxygen-absorbing resin composition, a general thermoplastic resin that is usually used for a film 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 it is. 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) (nylon 6, also known as polycaprolactam), 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 ( Heptamethylenepimelamide) (nylon 7,7), poly (octamethylenesuberamide) (nylon 8,8), poly (hexamethylene) Zeramide) (nylon 6,9), poly (nonamethylene azeramide) (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-azeraiamide caprolactam copolymer (nylon 6,6 / 6,9 / 6), poly (tetramethylenediamine-co-oxalic acid) (nylon) 4,2), polyamide of n-dodecanedioic acid and hexamethylenediamine Ron 6,12), the polyamide of dodecamethylenediamine and n- dodecanedioic acid (nylon 12,12), as well as such blends and copolymers, and other polyamides which are not specifically mentioned herein.

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

  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 layer (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) 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 and nickel, but also a Group I metal such as copper and silver; a Group IV metal such as tin, titanium and zirconium Group V such as vanadium; Group VI such as chromium; Group VII metal components such as manganese. Among these transition metal catalysts, the cobalt component is particularly suitable because of its high oxygen absorption rate.

  The transition metal catalyst (M) is generally used in the form of the above-described transition metal low-valent inorganic acid salt, organic acid salt, or complex salt. Examples of inorganic acid salts include halides such as chlorides, sulfur oxyacid salts such as sulfates, nitrogen oxyacid salts such as nitrates, phosphorus oxyacid salts such as phosphates, and silicates. On the other hand, examples of the organic acid salt include a carboxylate, a sulfonate, and a phosphonate. The carboxylate is suitable for the purpose of the present invention, and specific examples thereof include acetic acid, propionic acid, isopropylate. On acid, butanoic acid, isobutanoic acid, pentanoic acid, isopentanoic acid, hexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, decanoic acid, neodecane Acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, lindelic acid, tuzuic acid, petroceric acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, formic acid, oxalic acid, Examples include transition metal salts such as sulfamic acid and naphthenic acid. On the other hand, a complex with a transition metal complex is a β-diketone or a complex with a β-keto acid ester. 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 with respect to the thermoplastic resin contained as a main component. Hereinafter, 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 resin. 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 composition used in the present invention may optionally further 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 organics including oxidizers and heat stabilizers, lubricants, mold release agents, flame retardants, oxidation inhibitors, dyes, pigments and other colorants, UV stabilizers, particles and fiber fillers. Or inorganic fillers, reinforcing agents, nucleating agents, plasticizers, and other conventional additives known in the art. Such an additive can be used up to 10% by mass of the total amount of the oxygen-absorbing resin composition.

  The thickness of the oxygen absorbing layer can be appropriately determined so as to obtain a desired oxygen absorbing capacity, but is preferably 2 μm or more, more preferably 3 μm or more, and 20 μm or less, and further preferably 15 μm or less. If it is 2 μm or more, high oxygen gas barrier properties can be maintained for a long time even after deep drawing. If it is 20 μm or less, it is excellent in economic efficiency and a decrease in pinhole resistance can be avoided.

<Gas barrier layer>
In the film of the present invention, a gas barrier layer is disposed between the oxygen absorbing layer and the heat seal layer.
The oxygen absorbing layer described above is such that the oxygen gas that has been vented from the outside air side of the tray is oxidized by the oxidizable resin (S) by the action of the transition metal catalyst (M), so On the other hand, molecular chain scission occurs due to the oxidation reaction of the resin, and a low molecular weight organic component is generated. Examples of the low molecular weight organic component include aldehydes, fatty acids, ketones, alkanes, and alkenes, and have an odor. When they pass through the film and are ventilated toward the container, the taste and scent of the container are impaired and the commercial value is greatly reduced.
Therefore, it is important to suppress the aeration of these low molecular weight organic components to the container side from the viewpoint of keeping the flavor of the container good. From this viewpoint, a gas barrier is provided between the oxygen absorbing layer and the heat seal layer. Arrange the layers.

For the gas barrier layer, ethylene-vinyl acetate copolymer saponified product or polymetaxylene adipamide resin can be suitably used.
The ethylene content of the saponified ethylene-vinyl acetate copolymer is not particularly limited, but from the viewpoint of film formation stability, the lower limit is preferably 27 mol% or more, more preferably 32 mol% or more, and the upper limit. Is preferably 47 mol% or less, and more preferably 44 mol% or less.
In view of the gas barrier effect, it is more preferable to dispose an ethylene-vinyl acetate copolymer saponified layer. In applications where heat resistance or deterioration due to moisture is a concern, it is preferable to dispose a polymetaxylene adipamide resin layer having excellent heat resistance and water resistance.

The lower limit of the thickness of the gas barrier layer is preferably 2 μm or more, and more preferably 3 μm or more. The upper limit is preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 6 μm or less.
By setting it as 2 micrometers or more, the barrier property with respect to sufficient odor component can be provided, and stable film formation becomes possible. Moreover, by being 10 micrometers or less, besides being excellent in economical efficiency, the fall of pinhole resistance can be avoided.

  Further, by further disposing the gas barrier layer between the outer layer and the oxygen absorbing layer, the amount of oxygen gas reaching the oxygen absorbing layer from the outside of the tray can be reduced, which helps to maintain the function of the oxygen absorbing layer and also causes odor. Generation of low molecular weight organic components can be suppressed.

<Heat seal layer (inner layer)>
The inner layer of the film of the present invention includes a heat seal layer mainly composed of a polyolefin resin.
The polyolefin resin is not particularly limited. For example, propylene homopolymer, ethylene-propylene random or block copolymer, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene -Various resins such as methacrylic acid copolymer, ethylene-methyl methacrylate copolymer, polymethyl methacrylate, and ionomer.

Among these, a propylene homopolymer, an ethylene-propylene copolymer, and a linear low density polyethylene are preferable because they have both heat resistance and heat sealability.
In particular, when a polypropylene resin having a melting point of 150 ° C. or higher is used, high heat resistance can be imparted, so that it can be more suitably used as a microwave heated food tray.

In addition, when an easy peel layer is arranged on the inner layer, it is easy to use when the consumer opens the food packaging, and the commercial value of the food tray is increased.
The easy peel strength is preferably 0.1 N / 15 mm width or more and 20.0 N / 15 mm width or less at 25 ° C.
The easy peel layer may be any of cohesive failure type, delamination type, and interfacial exfoliation type, but the selection of cohesive failure type or delamination type having a wide seal temperature setting range and excellent peel stability is more preferred.

  In the case of the cohesive failure type, at least one kind is selected from the resins listed as the material constituting the heat seal layer (resin A), and as a resin having low compatibility with the resin A, high-density polyethylene, It is obtained by selecting any one from low density polyethylene, polypropylene, polybutene, and ethylene-vinyl acetate copolymer (resin B) and mixing resin A and resin B.

By adjusting the mixing ratio of the resin A and the resin B, it is possible to maintain a good heat seal property and obtain an appropriate easy peel strength.
The lower limit of the resin A is 55% or more, preferably 60% or more, more preferably 65% or more, and the upper limit is 90% or less, preferably 85% or less, more preferably 80% or less.
The lower limit of the resin B is 10% or more, preferably 15% or more, more preferably 20% or more, and the upper limit is 45% or less, preferably 40% or less, more preferably 35% or less.

  The heat seal layer may be composed of two or more layers. In that case, each layer may be made of the same resin or different resins. In the case of providing an easy peel layer, by disposing it on the surface layer of the film, it is possible to suppress appearance defects such as fuzz due to peeling, and the influence of lowering the strength of the entire film is reduced.

  The thickness of the inner layer is not particularly limited, but the lower limit is 25% of the total thickness in order to obtain good heat sealability and film formability as the total thickness of the inner layer, whether it is a single layer or two or more layers. Preferably, it is at least 30%, more preferably at least 35%. The upper limit is preferably 65% or less, more preferably 60% or less, and even more preferably 55% or less.

<Adhesive layer>
The film of the present invention can be provided with an adhesive layer as necessary for the purpose of increasing the adhesive strength between the coextruded layers. There may be one or more adhesive layers.

Examples of the resin that can be used as the adhesive layer include polyethylene such as low density polyethylene, linear low density polyethylene, medium density polyethylene, and high density polyethylene, and olefin resins such as polypropylene and ethylene-vinyl acetate copolymer.
In addition, for example, ethylene-vinyl acetate copolymer or ethylene elastomer, monobasic unsaturated fatty acid such as acrylic acid or methacrylic acid, or anhydride of dibasic fatty acid such as maleic acid, fumaric acid or itaconic acid A modified polyolefin resin in which is chemically bound can be exemplified.
Among them, it is preferable to use an adhesive resin based on polyethylene or polypropylene.

The thickness of the adhesive layer is not particularly limited, but the lower limit is preferably 3 μm or more and the upper limit is preferably 8 μm or less from the viewpoints of adhesiveness, workability, economy, and handleability.
When the thickness of the adhesive layer is 3 μm or more, the delamination strength can be improved. Further, if the adhesive layer is too thick, the transparency is deteriorated, the total thickness of the film is increased, and the manufacturing cost is increased. Therefore, the upper limit is desirably 8 μm or less.

<Whole film>
The total thickness of the film of the present invention is 20 μm or more and 50 μm or less. The lower limit is preferably 20 μm or more, more preferably 25 μm or more, and further preferably 30 μm or more. The upper limit is preferably 50 μm or less, more preferably 45 μm or less, and even more preferably 40 μm or less.

  When the total thickness is 20 μm or more, the suitability of printing and lamination that requires stiffness, flexibility, stretchability, thermal conductivity, and dimensional stability is improved. In addition, if the thickness is 50 μm or less, the thermal conductivity is good, so that it is excellent in processing suitability for thermal lamination and extrusion lamination, and it becomes easy to adjust conditions such as tension in the printing process, making tray production more efficient. Can be done.

The layer structure of the film of the present invention comprises an outer layer (A) mainly composed of polypropylene resin, another outer layer (B), an adhesive layer (C), an oxygen-absorbing resin layer (D), a gas barrier layer (E), and a first heat. When expressed by the seal layer (F), the second heat seal layer (G), and the easy peel layer (H), the following layer order can be exemplified, and (5) to (7) are preferable among them.
More preferable contents of the layer structure are when an ethylene-polypropylene copolymer is used for the other outer layer (B) and a polypropylene homopolymer or linear low density polyethylene is used for the heat seal layers (E) and (F). .

(1) A / D / E / F
(2) A / D / E / H

(3) A / C / D / E / C / F
(4) A / C / D / E / C / H

(5) A / B / C / D / E / C / F
(6) A / B / C / D / E / C / F / G
(7) A / B / C / D / E / C / F / H

(8) A / C / E / D / E / C / F
(9) A / C / E / D / E / C / F / H

  The film of the present invention can be produced using a known method. For example, a coextrusion inflation method, a coextrusion T-die method, and the like can be used. In particular, it is preferable to use a coextrusion T-die method from the viewpoint of uniformity of film thickness.

<Resin sheet>
Examples of the resin sheet used for the composite sheet of the present invention include various sheets made of, for example, polypropylene resin, polyethylene terephthalate resin, polystyrene resin, heat-resistant foamed polystyrene, polyvinyl chloride resin, high-density polyethylene resin, polyacrylonitrile resin, and the like. Can be mentioned.
Among them, a high melting point polypropylene resin sheet is preferable from the viewpoint of resistance to microwave ovens, and a polystyrene resin sheet is preferable from the viewpoint that a design imparting rigidity and a high-class feeling as a food tray can be given.

The form of the resin sheet may be a foamed sheet, an unstretched sheet, a stretched sheet, a colored sheet, a kneaded filler such as talc or titanium oxide, or a multilayer sheet using a recycled resin.
The thickness of the resin sheet is 300 μm or more and 1000 μm or less from the viewpoint of tray rigidity, moldability, and lightness. When the sheet form is a foamed sheet, it is lightweight and has formability and rigidity, so that it can be 2 mm or more and 5 mm or less, and preferably 3 mm or more and 4 mm or less.

Examples of a method for laminating the film of the present invention with various resin sheets include known techniques such as extrusion lamination, dry lamination, and thermal lamination.
Above all, from the viewpoint of rigidity, cost, impact resistance, and design, extrusion lamination with polypropylene resin sheet, dry lamination with polypropylene resin sheet after printing, and printing or coating on the outer layer surface of the film of the present invention Thermal lamination with a foamed polystyrene resin sheet is preferred.

Examples are shown below, but the present invention is not limited thereto.
<Evaluation method>
Films and composite sheets were prepared by the methods and configurations shown in each Example, and the following evaluations were performed.
In addition, the number in Table 1 shows the thickness (micrometer) of a sheet | seat, a layer, and a film.

(Evaluation of film; oxygen permeability)
The oxygen permeability of the produced film was measured in accordance with JIS K 7126 using OX-TRAN manufactured by MOCON under the conditions of 23 ° C. and 65% relative humidity, and evaluated according to the following criteria.
○: Less than 1 cc / (m ² · day · atm) ×: 1 cc / (m ² · day · atm) or more

(Evaluation of film; appearance)
The surface of the outer layer of the produced film was observed with an optical microscope and measured for surface roughness (VertScan, manufactured by Ryoka System).

(Production of tray)
The produced composite sheet was molded into a tray having a size of about 20 cm × about 15 cm and a depth of about 30 mm under the conditions of 220 ° C. preheater heating and plug molding using a heating vacuum molding machine, and used for the test.

(Production of food packaging)
The prepared tray is fried, filled with sausage, hamburger, and french fries, and the periphery of the lid and tray is heated using a gas replacement tray sealer at a seal temperature of 120 ° C and a seal time of 0.3 seconds. Sealed and an inert gas replacement sealed food package was produced.
For the cover material, a gas barrier vapor-deposited biaxially stretched PET film (12 μm) and a coextruded unstretched film of EVOH (8 μm) / Ny (28 μm) / AD (11 μm) / LLDPE (13 μm) layer structure And a laminated film obtained by dry-lamination with the EVOH surface facing each other.

(Evaluation of food packaging)
The prepared food package was opened, the lid was removed, and heating was carried out with a microwave oven for 1500 W for 30 seconds, the content food was taken out, and the state of the tray was visually observed.

(Evaluation of food packaging; openability)
Regarding the openability of the package, “○” indicates that it could be opened easily by hand without using a tool. Evaluated as “x”.

(Evaluation of food packaging; microwave oven suitability)
The food contact surface was evaluated as “◯” when the inner layer surface of the film was not discolored or melted, “△” when discolored, or “×” when discolored or melted. .

(Production of water package)
Water was fully poured into the above-prepared tray and hermetically sealed using an aluminum foil film as a lid.

(Evaluation of water package; flavor sensory evaluation)
The prepared water package is stored for 7 days at 30 ° C and 80% relative humidity, and then the sensory test is performed on the water in the package with the following indices using five testers in their 20s to 40s. ,
Taste 0: delicious, no difference
1: Delicious, but feels a slight difference
2: Delicious, feel a little different
3: Tasteless, feel the difference
4: Tasteless and clearly odorless 0: Odorless
1: I do not know what the odor is, but I feel it slightly (detection threshold)
2: Weak odor that can distinguish what kind of odor (recognition threshold)
3: Medium odor that feels comfortable
4: The average value of 5 strong odor testers was evaluated according to the following criteria.
○: 0 or more and less than 1
△: 1 or more and less than 3
X: 3 or more and 4 or less

The resin component which comprises each layer of an Example is as follows.
r-PP; ethylene-propylene random copolymer, melting point 138 ° C.
h-PP; propylene homopolymer, melting point 158 ° C.
LD; low density polyethylene, melting point 112 ° C
LL; linear low density polyethylene, melting point 122 ° C.
COC; cyclic polyolefin, glass transition temperature 102 ° C
EP; mixed composition of h-PP and LD, mass ratio 70:30

Oxygen absorption: A composition having a cobalt-containing concentration of 100 ppm, in which the following master batch (a) and pellets (b) were mixed.
Master batch (a): Saponified ethylene-vinyl acetate copolymer (ethylene 32 mol%) and cobalt stearate were mixed at a mass mixing ratio of 95: 5 using a twin-screw extruder under a nitrogen atmosphere, and the strands were extruded. Water bath quenched, pelletized and dried.
Pellets (b); Saponified ethylene-vinyl acetate copolymer (ethylene 32 mol%) and epoxy-functionalized polybutadiene were extruded at a mass mixing ratio of 95: 5 using a twin screw extruder under a nitrogen atmosphere, and the strands were extruded. Water bath is quenched and then pelletized and dried.

EVOH; Ethylene-vinyl acetate copolymer saponified product 32% by mole of ethylene
MXD; poly (meta-xylene adipamide)
AD: Polypropylene adhesive resin

(Examples 1-9, Comparative Examples 1-8)
A film was prepared by the T-die coextrusion non-stretching method, and the outer layer surface was subjected to corona treatment.
Hereinafter, the layer configuration order will be described from the outer layer side. The r-PP + LD of the outer layer on the surface layer side is a mixed composition with a mass ratio of 85:15.

Example 1
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / EVOH (4 μm) / AD (4 μm) / r-PP (10 μm) / h-PP (4 μm)
A polypropylene resin sheet having a thickness of 500 μm was extrusion laminated on the outer layer side of the produced film to produce a composite sheet.

(Example 2)
Using the same film as in Example 1, printing was performed on the surface of the outer layer, and then dry lamination was performed on the outer layer side using a polypropylene resin sheet having a thickness of 500 μm and a urethane-based adhesive to prepare a composite sheet.

(Example 3)
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / EVOH (4 μm) / AD (4 μm) / r-PP (10 μm) / EP (3 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

Example 4
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / MXD (4 μm) / AD (4 μm) / r-PP (10 μm) / h-PP (3 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Example 5)
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / MXD (4 μm) / AD (4 μm) / r-PP (10 μm) / EP (3 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Example 6)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / oxygen absorption (2 μm) / MXD (4 μm) / AD (4 μm) / h-PP (14 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Example 7)
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / EVOH (4 μm) / AD (4 μm) / r-PP (10 μm) / h-PP (4 μm)
On the outer layer side of the produced film, it was thermally laminated with a 3000 μm thick polystyrene foam resin sheet to produce a composite sheet.

(Example 8)
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / EVOH (4 μm) / AD (4 μm) / r-PP (10 μm) / EP (4 μm)
On the outer layer side of the produced film, it was thermally laminated with a 3000 μm thick polystyrene foam resin sheet to produce a composite sheet.

Example 9
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / MXD (4 μm) / AD (4 μm) / r-PP (10 μm) / EP (3 μm)
On the outer layer side of the produced film, it was thermally laminated with a 3000 μm thick polystyrene foam resin sheet to produce a composite sheet.

(Comparative Example 1)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / EVOH (5 μm) / AD (4 μm) / r-PP (12 μm) / h-PP (4 μm)
A polypropylene resin sheet having a thickness of 500 μm was extrusion laminated on the outer layer side of the produced film to produce a composite sheet.

(Comparative Example 2)
Using the same film as Comparative Example 1, printing was performed on the surface of the outer layer, and then dry lamination was performed on the outer layer side using a polypropylene resin sheet having a thickness of 500 μm and a urethane-based adhesive to prepare a composite sheet.

(Comparative Example 3)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / EVOH (10 μm) / AD (4 μm) / r-PP (12 μm) / h-PP (4 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Comparative Example 4)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / EVOH (10 μm) / AD (4 μm) / r-PP (12 μm) / EP (4 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Comparative Example 5)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / MXD (10 μm) / AD (4 μm) / r-PP (12 μm) / h-PP (4 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Comparative Example 6)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / oxygen absorption (5 μm) / AD (4 μm) / r-PP (12 μm) / h-PP (4 μm)
On the outer layer side of the produced film, a polypropylene resin sheet having a thickness of 500 μm was dry-laminated using a urethane adhesive to produce a composite sheet.

(Comparative Example 7)
r-PP + LD (6 μm) / r-PP (5 μm) / AD (4 μm) / oxygen absorption (5 μm) / AD (4 μm) / r-PP (12 μm) / h-PP (4 μm)
On the outer layer side of the produced film, it was thermally laminated with a 3000 μm thick polystyrene foam resin sheet to produce a composite sheet.

(Comparative Example 8)
r-PP + LD (5 μm) / r-PP (4 μm) / AD (4 μm) / oxygen absorption (5 μm) / AD (4 μm) / COC (14 μm) / LL (3 μm)
On the outer layer side of the produced film, it was thermally laminated with a 3000 μm thick polystyrene foam resin sheet to produce a composite sheet.

The oxygen gas permeability of the films of Examples 1 to 9 is 0.5 to 0.8 cc / (m ² · day · atm), and ketones and aldehydes generated when the oxygen absorption layer reacts with oxygen It was possible to prevent low molecular weight products such as those from moving into the contents and deteriorating the taste and smell of the contents.

  In Examples 1 to 6, polypropylene resin was used for the outer layer and the heat seal layer, and the thickness of the outer layer was 69% of the thickness of the inner layer, so that no deformation occurred in the microwave heating test. In Examples 7 to 9, since the resin sheet was foamed polystyrene, melting and deformation were caused by the microwave treatment.

Since the comparative examples 1-5 did not arrange | position the oxygen absorption layer, oxygen permeability was 2.2-5.5 cc / (m < ² > * day * atm), and was high compared with the Example.

Comparative Examples 6-8 did not arrange a gas barrier layer, and deteriorated taste and odor. This is probably because organic components such as ketones and aldehydes generated by the reaction of the oxygen absorbing layer with oxygen migrated to the contents.
From these evaluation results, it can be seen that the film of the present invention is very excellent in oxygen gas barrier properties, and can impart easy peel properties and microwave oven heat resistance without deteriorating the odor and taste of the contents.

The coextruded unstretched film of the present invention and the composite sheet laminated with the resin sheet are very excellent in oxygen barrier properties and heat sealability. Furthermore, the seal sealing property with the lid and the suitability of the inert gas pack make it possible to extend the food package taste and shelf life and reduce the loss of food and packaging materials. Also, by selecting various resin sheets as the sheets to be laminated, it is possible to produce a tray that also has microwave oven heat resistance.
As mentioned above, the film and composite sheet of this invention can contribute to the improvement of convenience over food manufacturing industry, a sales industry, a packaging material industry, and a consumer.

1: Coextrusion unstretched film
2: Resin sheet
3: Tray molded composite sheet
4: Lid
5: Containment

Claims (5)

  A co-extrusion unstretched film that is laminated on a resin sheet having a thickness of 300 μm or more to form a tray, and in that order from the container side of the tray, a heat seal layer, a gas barrier layer, and an oxygen absorption layer mainly composed of a polyolefin resin And a coextrusion unstretched film having an outer layer mainly composed of polypropylene resin.   The coextruded unstretched film according to claim 1, wherein the outer layer contains a low density polyethylene resin of 5% by mass or more and 20% by mass or less.   The coextruded unstretched film according to claim 1 or 2, wherein the outer layer surface is printed. A composite sheet for tray molding formed by laminating the coextruded unstretched film according to any one of claims 1 to 3 on a resin sheet having a thickness of 300 µm or more,
A composite sheet for tray molding, wherein the resin sheet is one selected from the group consisting of polypropylene resin, polyethylene terephthalate resin, polystyrene resin, heat-resistant foamed polystyrene resin, polyvinyl chloride resin, high-density polyethylene resin, and polyacrylonitrile resin.   The tray formed by arrange | positioning the composite sheet of Claim 4 and arrange | positioning the co-extrusion non-stretched film side in the accommodation side.

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