Laminated film with gas barrier property, packaging material, and separation and recovery method

Abstract

Provided are: a laminated film with a gas barrier property formed by providing a resin layer containing a vinyl alcohol-based polymer between an olefin-based resin film and a printing layer or a surface coating layer; a packaging material using the same; a recycled plastic; and a separation and recovery method that has a step for immersing the laminated film with a gas barrier property in a stripping solution, and a step for recovering each layer that has been separated and detached. It is preferable that the laminated film with a gas barrier property comprises a resin layer containing a vinyl alcohol-based polymer and a polyalkyleneimine or hydrazide between the olefin-based resin film and the printing layer or the surface coating layer. The olefin-based resin film is preferably a polyethylene resin film.

Description

Gas barrier laminated film, packaging material, and separation and recovery method

[0001] The present invention relates to a recyclable gas barrier laminate film, a packaging material, and a separation and recovery method.

[0002] Gas barrier materials are used in various fields to prevent the intrusion of gases such as moisture and oxygen from the outside air. For example, packaging materials used to package foods and beverages are required to have oxygen barrier properties to prevent the intrusion of oxygen from the outside in order to protect the contents and preserve the food for a long period of time, as well as carbon dioxide barrier properties and barrier properties against various aroma components. Furthermore, gas barrier laminate films using plastic film substrates as alternatives to conventional glass substrates have been considered as sealing materials for protecting the internal structure of solar cells and electronic devices and blocking oxygen and water vapor from the outside, with the aim of providing thinner, lighter, or more flexible products. Known methods for producing such gas barrier laminate films include applying a coating agent containing polyvinyl alcohol, ethylene vinyl alcohol, or the like to a plastic film substrate (see Patent Documents 1 and 2).

[0003] Meanwhile, with the mandatory recycling of plastic containers and packaging, these gas barrier laminate films are also being required to be collected, sorted, and reused after disposal. The most common method for recycling plastic waste involves crushing or alkali treatment after collection, separating the waste based on specific gravity, and then sorting and reusing it. However, there has not yet been sufficient research into applying such general recycling methods to gas barrier laminate films.

[0004] JP 2017-115076 A

[0005] An object of the present invention is to provide a recyclable gas barrier laminate film and a packaging material using the same.

[0006] The present inventors have conducted extensive research focusing on the laminate structure of gas barrier laminate films and have found that a gas barrier laminate film having a resin layer containing polyvinyl alcohol between an olefin resin film and a printing layer or a surface coating layer has sufficient gas barrier film functionality, while also allowing the laminate film to be easily separated into single-layer films by a conventional alkali treatment.

[0007] That is, the present invention provides a gas barrier laminate film comprising an olefin resin film and a print layer or a surface coating layer, and a resin layer containing a vinyl alcohol polymer disposed between the olefin resin film and the print layer or surface coating layer.

[0008] The present invention also provides a packaging material using the gas barrier laminate film described above.

[0009] The present invention also provides a recycled plastic using the gas barrier laminate film described above.

[0010] The present invention also provides a separation and recovery method comprising the steps of immersing the gas barrier laminate film described above in a stripping solution and recovering each layer that has been separated and detached.

[0011] According to the present invention, it is possible to provide a gas barrier laminate film which has sufficient function as a gas barrier film and can be easily separated into single layer films by a general alkali treatment.

[0012] (Olefin Resin Film) The olefin resin film used in the present invention can be a film made of a thermoplastic resin containing an olefin resin as a main component. Specific examples of the olefin resin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear (linear) low-density polyethylene, polypropylene, ethylene-propylene copolymers, α-olefin polymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, cyclic olefin resins, ionomer resins, and polymethylpentene; and modified olefin resins obtained by modifying an olefin resin with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids.

[0013] It is also preferable to use a film made of a material containing biomass-derived components as the film substrate. Biomass films are commercially available from various companies, and for example, sheets such as those listed in the list of biomass-certified products listed by the Japan Organics Recycling Association can be used.

[0014] Specifically, well-known films are made from biomass-derived ethylene glycol. Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene oxide by a conventionally known method to produce ethylene glycol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used.

[0015] Alternatively, products using biomass raw materials classified by the biomass plastic content specified in ISO 16620 or ASTM D6866 are also on the market. Radioactive carbon-14C exists in the atmosphere at a rate of 1 in 1012 particles, and this rate is the same for atmospheric carbon dioxide, so this rate remains the same even in plants that fix this carbon dioxide through photosynthesis. Therefore, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the plant-derived resin content in the resin, i.e., the biomass plastic content, can be determined. Examples of plant-derived low-density polyethylene, which is a biomass plastic having a biomass plastic content of 80% or more, preferably 90% or more as specified by ISO 16620 or ASTM D6866, include products manufactured by Braskem under the trade names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films using these as raw materials can be suitably used.

[0016] For example, biomass polyolefin films, such as biomass polyethylene films and biomass polyethylene-polypropylene films, containing polyethylene resins made from biomass-derived ethylene glycol are known as alternatives to conventional polyolefin films made from petroleum-based raw materials. The polyethylene resin is not particularly limited except that biomass-derived ethylene glycol is used as part of the raw material. Examples of the polyethylene resin include ethylene homopolymers and copolymers of ethylene and α-olefins containing ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units). These can be used alone or in combination of two or more. The α-olefin constituting the copolymer of ethylene and α-olefin is not particularly limited, and examples include α-olefins having 4 to 8 carbon atoms, such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins, such as low-density polyethylene resins, medium-density polyethylene resins, and linear low-density polyethylene resins, can be used. Among these, from the viewpoint of making it even more difficult for damage such as holes or tears to occur even when films rub against each other, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene or a copolymer of ethylene and 1-octene) is preferred, and linear low-density polyethylene resin having a density of 0.910 to 0.925 g / cm is more preferred.

[0017] The biomass film may be a laminate of multiple biomass films, or may be a laminate of a conventional petroleum-based film and a biomass film.

[0018] The substrate may be subjected to any surface treatment, for example, a physical treatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, or flame treatment, a chemical treatment such as oxidation treatment using chemicals, or other treatments.

[0019] The substrate can be produced from the above-mentioned resin by a conventionally known film-forming method such as extrusion, cast molding, T-die molding, cutting, inflation, etc. The substrate may be an unstretched film, or may be one that has been stretched uniaxially or biaxially using a tenter system, a tubular system, or the like, from the viewpoint of the strength, dimensional stability, and heat resistance of the film (1).

[0020] The substrate may contain additives as needed. Specifically, plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, and pigments may be added for the purpose of improving or modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, mold releasability, flame retardancy, mildew resistance, electrical properties, strength, etc. The amount of additive added is adjusted within a range that does not affect other performance properties or recyclability.

[0021] The thickness of the substrate is not particularly limited and may be appropriately selected from the range of 0.1 to 300 μm in terms of moldability and transparency. It is preferably in the range of 0.3 to 100 μm. If the thickness is less than 0.1 μm, the strength may be insufficient, and if it exceeds 300 μm, the rigidity may be too high, making processing difficult.

[0022] From the viewpoint of recycling, it is preferable that the layer structure is as simple as possible, but from the viewpoint of distribution of the packaging material, printing is often required to indicate the contents of the packaging material or a description or name of the product. Printing is often also performed on the substrate.

[0023] (Printed Layer) The printed layer is a layer on which characters, figures, symbols, and other desired designs are printed. The printing method and printing ink are not particularly limited, and known printing methods and printing inks can be used. Printing inks using methods such as gravure printing, flexographic printing, lithographic offset printing, and inkjet recording printing are often used for the film used as the substrate. Printing inks that combine these printing methods with methods of curing using active energy rays such as ultraviolet (UV), LED, and electron beam (EB), or methods of curing using heat, are also used. Depending on the solvent used, inks may be referred to as aqueous inks or organic solvent-based inks.

[0024] Specific examples include gravure printing ink and flexographic printing ink (in some industries, gravure printing ink and flexographic printing ink are sometimes referred to as liquid ink), ultraviolet-curable ink for lithographic offset printing, electron-beam-curable ink for lithographic offset printing, ultraviolet-curable ink for inkjet recording and printing, and electron-beam-curable ink for inkjet recording and printing.

[0025] The position where the printed layer printed using these inks is provided is arbitrary, and it may be provided on the first substrate, or a substrate on which a separate printed layer is provided may be one of the constituent components of the laminate of the present invention, and the position is arbitrary. Furthermore, the ink may contain a resin, a colorant, and a solvent as essential components, or it may be a so-called clear ink that contains a resin and a solvent but does not substantially contain a colorant. Below, we will explain the liquid inks that are most commonly used for printing on films.

[0026] The resin used in the liquid ink is not particularly limited and may include, for example, acrylic resin, polyester resin, styrene resin, styrene-maleic acid resin, maleic acid resin, polyamide resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-acrylic copolymer resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyvinyl chloride resin, chlorinated polypropylene resin, cellulose-based resin, epoxy resin, alkyd resin, rosin-based resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin, etc., and one or more of these may be used in combination. Preferably, at least one or two or more selected from polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, and cellulose-based resin are used.

[0027] Colorants used in liquid inks include inorganic pigments such as titanium oxide, red iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, Prussian blue, ultramarine, carbon black, and graphite; organic pigments such as soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments; and extender pigments such as calcium carbonate, kaolin clay, barium sulfate, aluminum hydroxide, and talc.

[0028] Liquid inks for film printing are often organic solvent-based inks. The organic solvent used preferably does not contain an aromatic hydrocarbon organic solvent. More specific examples include alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. These may be used alone or in combination of two or more.

[0029] (Surface Coating Layer) The surface coating layer is provided for the purpose of protecting the olefin-based resin film. A surface coating layer having heat resistance is particularly preferred, since it can suppress the occurrence of wrinkles caused by a heat seal bar used during processing in bag making, even if the olefin-based resin film is a resin with poor heat resistance such as a polyethylene-based resin. The surface coating layer can be provided by applying a coating agent (A) (hereinafter sometimes simply referred to as coating agent (A)).

[0030] The heat-resistant coating agent (A) preferably contains, as a main component, a polymeric compound whose homopolymer glass transition temperature (hereinafter sometimes referred to as Tg) is 70°C or higher, and preferably contains, for example, a compound having a cellulose skeleton, a benzene ring skeleton, an isocyanuric ring skeleton, or an alicyclic skeleton. Specific examples of the resin composition include cellulose derivatives such as nitrocellulose, cellulose acetate, cellulose propionate, and cellulose butyrate; polyester resins having a benzene ring such as phthalic acid, naphthalenedicarboxylic acid, and ethylene oxide (hereinafter sometimes referred to as EO) adducts of bisphenol A, and / or an alicyclic skeleton such as cyclopentanediol and dimethyloltricyclodecane; aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalene diisocyanate; alicyclic isocyanates such as isocyanuric triisocyanate and norbornene diisocyanate; and / or urethane resins in which isocyanuric triisocyanate is bonded to a polyol and / or tris(2-hydroxyethyl)isocyanurate. Polyisocyanates using the above-mentioned isocyanates may also be used as the curing agent. Compounds having a benzene ring and an unsaturated double bond, such as styrene and phenoxydiethylene glycol acrylate, and / or compounds having an alicyclic structure and an unsaturated double bond, such as isobornyl acrylate and dicyclopentanyl acrylate, and radical copolymers such as (meth)acrylates are also preferably used. Furthermore, resins with low Tg may be mixed in consideration of adhesion to olefin films. The total amount of the cellulose skeleton, benzene ring skeleton, isocyanuric ring skeleton, and alicyclic skeleton of the aforementioned compounds is preferably 20 to 90% by mass, and more preferably 30 to 80% by mass, of the solid content of the heat-resistant coating layer (A). The Tg of the homopolymer is more preferably 80°C or higher, and most preferably 100°C or higher.

[0031] The coating agent (A) may be colored. The colorant is not particularly limited, and examples thereof include inorganic pigments, organic pigments, and dyes used in general inks, paints, and recording agents, such as those used in the printing layer (E) described below. Among these, pigments are preferred. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, etc. In addition, both non-acid-treated pigments and acid-treated pigments can be used.

[0032] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, and gypsum. Among the inorganic pigments, titanium oxide is particularly preferred. Titanium oxide exhibits a white color and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide is preferably treated with silica and / or alumina. Examples of inorganic pigments other than white include aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, and zircon. Aluminum is in powder or paste form, but is preferably used in paste form from the viewpoints of handleability and safety. Whether leafing or non-leafing is used is appropriately selected from the viewpoints of brightness and density.

[0033] Furthermore, the coating agent (A) preferably uses inorganic fine particles such as alumina, magnesia, titania, zirconia, and silica (quartz, fumed silica, precipitated silica, silicic anhydride, fused silica, crystalline silica, ultrafine amorphous silica, etc.) as aggregates due to their excellent heat resistance. Alternatively, boron nitride, aluminum nitride, alumina oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, etc. are preferred due to their excellent thermal conductivity. The inorganic fine particles may be used alone or in combination of two or more types. The shape of the silica fine particles is not particularly limited, and spherical, hollow, porous, rod-like, plate-like, fibrous, or amorphous silica particles may be used. For example, commercially available hollow silica fine particles such as Silinax manufactured by Nittetsu Mining Co., Ltd. may be used.

[0034] The primary particle diameter of the inorganic fine particles is preferably in the range of 5 to 200 nm. If the diameter is 5 nm or more, the inorganic fine particles are well dispersed in the dispersion, and if the diameter is 200 nm or less, the strength of the cured product is good. A diameter of 10 nm to 100 nm is more preferable. The inorganic fine particles can be blended in a ratio of 5 to 90 wt % based on the total solid content of the coating agent (A) and the inorganic fine particles, and the blending amount can be changed as needed depending on the purpose. In particular, a ratio of 20 mass % or more is preferable.

[0035] Waxes, silicon additives, and organic beads can be added to the coating agent (A) to prevent scratches on the coated film, prevent blocking during laminate formation, and improve processability during bag making after the laminate is produced. Specifically, waxes such as amide wax, polypropylene wax, polyethylene wax, paraffin wax, carnauba wax, and rice wax, ethylene oxide (EO) adducts of dimethylsiloxane, silicon additives of modified silicon, and organic beads made of acrylic, nylon, urethane, or epoxy can be added.

[0036] The solvent used in the coating agent (A) is not particularly limited, and examples thereof include water, aromatic hydrocarbon organic solvents such as toluene, xylene, Solvesso #100, Solvesso #150, etc.; aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, decane, etc.; and various ester organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, butyl propionate, etc. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and glycol ethers such as ethylene glycol (mono- and di-)methyl ether, ethylene glycol (mono- and di-)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono- and di-)methyl ether, diethylene glycol (mono- and di-)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono- and di-)methyl ether, propylene glycol (mono- and di-)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono- and di-)methyl ether. These can be used alone or in combination of two or more. Furthermore, to more effectively carry out coating, an antifoaming agent or a leveling agent can be used.

[0037] (Resin layer containing vinyl alcohol-based polymer) In the present invention, the resin layer containing a vinyl alcohol-based polymer is a layer that imparts gas barrier properties, and can be provided by applying a coating agent (B) containing a vinyl alcohol-based polymer (hereinafter, may be simply referred to as coating agent (B)).

[0038] (Vinyl Alcohol Polymer) The vinyl alcohol polymer may be a hydrolyzate of a vinyl ester homopolymer or copolymer obtained by a known, commonly used method, or a reaction product of a vinyl ester homopolymer or copolymer hydrolyzate with an aldehyde obtained by a known, commonly used method.

[0039] Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, and vinyl benzoate, and these can be used alone or in combination of two or more. Vinyl acetate is preferred.

[0040] Examples of polymerizable compounds copolymerizable with vinyl esters include ethylene, propene, 1-butene, isobutylene, 1,3-butadiene, isopropenyl acetate, 2-propenyl acetate, 3,4-diacetoxy-1-butene, 2,2-dialkyl-4-vinyl-1,3-dioxolanes such as 2,2-dimethyl-4-vinyl-1,3-dioxolane, 3,4-dihydroxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-hydroxy-1-butene, 4-acyloxy-3-hydroxy-1-butene, 3,4-diacyloxy-2-methyl-1-butene, 4,5-dihydroxy-1-pentene, 4,5-diacyloxy-1-pentene, 4,5 3,4-diacyloxy-1-butenes such as 4,5-dihydroxy-3-methyl-1-pentene, 5,6-dihydroxy-1-hexene, and 5,6-diacyloxy-1-hexene, styrene, α-methylstyrene, vinyl chloride, acrylonitrile, maleic anhydride, methyl acrylate, methyl methacrylate, N-vinyl-N-methylformamide, vinylacetamide, N-vinylformamide, N-(hydroxymethyl)-N-vinylformamide, hydroxyethyl acrylate, methyl vinyl ketone, and diacetone acrylamide, and these can be used alone or in combination of two or more. Among these, ethylene, isopropenyl acetate, and 2-propenyl acetate are preferred.

[0041] When a vinyl ester and a polymerizable compound are used in combination, the amounts used can be adjusted as appropriate. From the viewpoint of gas barrier properties, however, the amount of the polymerizable compound blended is preferably kept to 60 mol % or less, more preferably 25 mol % or less, of the total amount of the vinyl ester and the polymerizable compound (a2).

[0042] The degree of polymerization of the vinyl alcohol polymer or the vinyl ester polymer that is its precursor is not particularly limited, but is, for example, 500 to 10,000, more preferably 800 to 6,000, and even more preferably 1,000 to 3,000. This makes it possible to provide a coating agent that has an excellent balance between gas barrier properties and coatability.

[0043] Aldehydes used for acetalization include aliphatic aldehydes such as formaldehyde, acetaldehyde, propylaldehyde, butylaldehyde, octylaldehyde, and dodecylaldehyde; alicyclic aldehydes such as cyclohexanecarbaldehyde; aromatic aldehydes such as benzaldehyde, naphthaldehyde, anthraldehyde, phenylacetaldehyde, tolualdehyde, dimethylbenzaldehyde, cuminaldehyde, and benzylaldehyde; cyclohexene aldehyde, dimethylcyclohexene aldehyde, acrylonitrile, and the like; Examples of the aldehyde include unsaturated aldehydes such as chlorine; aldehydes having a heterocycle such as furfural and 5-methylfurfural; hemiacetals such as glucose and glucosamine; and aldehydes having an amino group such as 4-aminobutyraldehyde. In addition, aliphatic ketones such as 2-propanone, methyl ethyl ketone, 3-pentanone, and 2-hexanone; alicyclic ketones such as cyclopentanone and cyclohexanone; and aromatic ketones such as acetophenone and benzophenone can be used alone or in combination of two or more.

[0044] As the acid catalyst used in the acetalization, conventionally known organic or inorganic acids such as acetic acid, paratoluenesulfonic acid, nitric acid, sulfuric acid, and hydrochloric acid can be used.

[0045] Specific examples of suitable vinyl alcohol polymers include polyvinyl alcohol, ethylene vinyl alcohol, and polyvinyl butyral. These may be used alone or in combination. From the viewpoint of the balance between gas barrier properties and adhesion, it is more preferable to use either polyvinyl alcohol or ethylene vinyl alcohol, or both.

[0046] The vinyl alcohol polymer preferably has a saponification degree of 90% or more, more preferably 95% or more, because it has excellent gas barrier properties. It may also be 100%. The saponification degree can be measured by FTIR using, for example, a Nicolet 5700 FTIR spectrometer controlled by OMNIC software. The vinyl alcohol polymer is preferably obtained by acetalizing a precursor having a saponification degree of 95% or more.

[0047] (Polyalkyleneimine or Hydrazide) The vinyl alcohol polymer can be preferably used in combination with a polyalkyleneimine or a hydrazide.

[0048] (Polyalkyleneimine) The polyalkyleneimine is a resin having a polyalkyleneimine skeleton, and is obtained by polymerizing one or more alkyleneimines (e.g., ethyleneimine, propyleneimine) by a conventional method. By using a vinyl alcohol polymer and a polyalkyleneimine in combination, the gas barrier properties of the coating agent (B) can be maintained while improving the adhesion to an olefin-based substrate.

[0049] The polyalkyleneimine may be a linear polyalkyleneimine consisting of a linear polyalkyleneimine chain, or a branched polyalkyleneimine having a branched polyalkyleneimine chain. Examples of polyalkyleneimines include polyethyleneimine and polypropyleneimine. The polyalkyleneimine may have a substituent (e.g., a hydroxypropyl group or a hydroxyethyl group) introduced into at least some of the nitrogen atoms of the polyalkyleneimine chain. Polyalkyleneimines modified with organometallic compounds such as tetraisopropyl titanate, tetra-normal-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, polyhydroxytitanium stearate, titanium bisacetylacetonate, titanium tetraacetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium ethylacetoacetate, titanium lactate, titanium triethanolamine, and titanium stearate may also be used, and two or more types of polyalkyleneimines may also be used in combination.

[0050] Polyalkyleneimine has an amino group (NHR group, NH ２It is believed that the ethylene groups and the ethylene groups contribute to improving the adhesion between the vinyl alcohol polymer and the olefin film, and since this is effective in improving adhesion, it is preferable that the polyalkyleneimine contains a branched polyalkyleneimine. The degree of branching of the polyalkyleneimine can be expressed by the proportion of primary, secondary, and tertiary amino groups contained in the polyalkyleneimine. This can be appropriately adjusted depending on the vinyl alcohol polymer used and its blending amount, but as an example, it is preferable to use a polyalkyleneimine in which the proportion of primary amino groups is 20 to 40%, the proportion of secondary amino groups is 30 to 60%, and the proportion of tertiary amino groups is 20 to 35%. The proportions of primary, secondary, and tertiary amine groups contained in the polyalkyleneimine are １３ The branched polyalkyleneimine can be measured by C-NMR spectroscopy. The branched polyalkyleneimine is preferably a branched polyethyleneimine.

[0051] The number-average molecular weight of the polyalkyleneimine is preferably 5,000 or more, more preferably 9,000 or more, and even more preferably 50,000 or more, because this provides excellent adhesion. The upper limit is not particularly limited, but an example is 100,000 or less. The number-average molecular weight of the polyalkyleneimine is measured by GPC (gel permeation chromatography) using pullulan as a standard substance.

[0052] In the coating agent (B), the blending amount of polyalkylimine is preferably 1% by mass or more and 90% by mass or less of the total amount of the vinyl alcohol polymer and the polyalkylimine. This makes it possible to more reliably improve adhesion to olefin-based substrates while maintaining gas barrier properties. More preferably, it is 10% by mass or more and 50% by mass or less. If the coating agent of the present invention does not contain polyalkyleneimine, adhesion to olefin-based substrates is insufficient.

[0053] (Hydrazide) By using a hydrazide in combination with the vinyl alcohol polymer having a reactive functional group, the water resistance of the coating film can be improved while maintaining the gas barrier properties of the coating agent (B).

[0054] Examples of the hydrazide include dicarboxylic acid dihydrazides containing 2 to 10, particularly 4 to 6, carbon atoms, such as adipic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide; and aliphatic water-soluble dihydrazines having 2 to 4 carbon atoms, such as ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, and butylene-1,4-dihydrazine.

[0055] The coating agent (B) may contain a resin other than the vinyl alcohol polymer. Examples of such resins include cellulose resins, polyesters, polyurethanes, vinyl resins such as homopolymers or copolymers of olefins or styrene, acrylic resins, epoxy resins, amide resins, natural rubber, and composites thereof (e.g., core-shell resins), and these resins may be used alone or in combination of two or more. Since gas barrier properties may be reduced if the amount of resin is too large, the amount of resin is preferably kept to 10% by mass or less of the vinyl alcohol polymer. It is more preferably 5% by mass or less, and even more preferably 1% by mass or less. It may even be 0% by mass.

[0056] The solvent for the coating agent (B) is preferably an aqueous solvent. Examples of the aqueous solvent include water and water-soluble organic solvents that dissolve in water. Examples of water that can be used include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water. From the perspective of long-term storage, it is preferable to use water that has been sterilized by ultraviolet irradiation or the addition of hydrogen peroxide, for example, in order to prevent the growth of mold or bacteria.

[0057] Examples of water-soluble organic solvents include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, and hexanediol; glycol esters such as propylene glycol laurate; diethylene glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, and carbitol; glycol ethers such as cellosolves containing propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether; alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, and pentyl alcohol; lactones such as sulfolane, esters, ketones, and γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidone; and various other solvents known as aqueous organic solvents, such as glycerin and its polyalkylene oxide adducts. These aqueous organic solvents can be used alone or in combination of two or more.

[0058] The coating agent (B) may further contain additives such as a crosslinking agent capable of reacting with a functional group possessed by the layered inorganic compound, the vinyl alcohol polymer, or the polyalkylimine (A2), an inorganic filler, an antifoaming agent, a stabilizer (antioxidant, heat stabilizer, ultraviolet absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, and a leveling agent.

[0059] Examples of layered inorganic compounds include natural smectites such as montmorillonite, synthetic smectites, natural mica, synthetic mica, hydrotalcite, and talc, as well as lipophilic-treated smectites and lipophilic synthetic mica obtained by organically treating these compounds. The use of layered inorganic compounds improves the gas barrier properties of the coating agent, but tends to reduce adhesion to olefin-based substrates. The blending amount of the layered inorganic compound is preferably 10 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the resin (A), as this provides an excellent balance between gas barrier properties and adhesion.

[0060] Examples of crosslinking agents include aldehydes such as formalin and glutaraldehyde; acetals such as diacetalized products of glutaraldehyde; aliphatic polyisocyanates such as hexamethylene diisocyanate and its derivatives (adduct, nurate, biuret, etc.), aromatic aliphatic polyisocyanates such as xylylene diisocyanate and its derivatives, aromatic polyisocyanates such as toluene diisocyanate and its derivatives, and isocyanates such as urethane prepolymers which are reaction products of these isocyanates with polyols; epoxies; titanium, silicon, aluminum, zirconium, Examples of the isocyanate include organometallic compounds of boron or the like with alkoxides or the like; methylol ureas such as methylol urea and methylol melamine; carboxyl group-containing polymers such as polyacrylic acid polymers and maleic anhydride polymers; carbodiimides such as p-phenylene-bis(2,6-xylylcarbodiimide), tetramethylene-bis(t-butylcarbodiimide), and cyclohexane-1,4-bis(methylene-t-butylcarbodiimide); boric acid; and titanium lactate. As the isocyanate, a blocked isocyanate using a known blocking agent or an emulsion-type isocyanate may be used.

[0061] The method for applying the coating agent (B) is not particularly limited, and examples thereof include spraying, spin coating, dipping, roll coating, blade coating, doctor roll coating, doctor blade coating, curtain coating, slit coating, screen printing, inkjet printing, dispensing, die coating, direct gravure coating, reverse gravure coating, flexography, knife coating, and dot coating.

[0062] The thickness of the resin layer containing the vinyl alcohol polymer obtained by applying the coating agent (B) can be appropriately adjusted depending on the type of substrate and the desired level of gas barrier property, but is, for example, 0.2 μm or more and 2.0 μm or less. If the thickness is too thin, the gas barrier property cannot be expected to be significantly improved, and if it is too thick, the adhesion may decrease.

[0063] (Method for producing gas barrier laminate film) The gas barrier laminate film of the present invention can be obtained by applying the coating agent (B) to the olefin resin film, drying it as necessary, to provide a resin layer containing the vinyl alcohol polymer, and then providing the printed layer or the surface coating layer. The surface coating layer can also be provided after providing the printed layer.

[0064] (Adhesive) The gas barrier laminate film of the present invention can be further bonded to another substrate using an adhesive. Alternatively, another substrate can be laminated onto the gas barrier laminate film of the present invention by extrusion. The other substrate can be the same as those described above. For example, a two-component curing urethane solvent-based or solventless adhesive commonly used for bonding films can be used as the adhesive. It is preferable to use an adhesive that results in an aromatic ring concentration of 0.5 mmol / g or more and 7.0 mmol / g or less in the cured coating film, and more preferably an adhesive that results in an aromatic ring concentration of 3.5 mmol / g or more and 7.0 mmol / g or less, since this will result in a laminate with excellent gas barrier properties.

[0065] (Laminate Structure) An example of a specific embodiment of the gas barrier laminate film of the present invention is given below. Of course, the gas barrier laminate film of the present invention is not limited to this embodiment. For example, if the layer that will become the outermost layer in the packaging material is referred to as the first substrate and the layer that will become the sealant layer is referred to as the second substrate, specific examples of the laminate structure include the following: First substrate / gas barrier coating layer First substrate / gas barrier coating layer / adhesive layer / second substrate First substrate / adhesive layer / gas barrier coating layer / second substrate First substrate / adhesive layer / gas barrier coating layer / deposited layer / second substrate First substrate / gas barrier coating layer / printed layer / adhesive layer / second substrate First substrate / printed layer / gas barrier coating layer / adhesive layer / second substrate First substrate / printed layer / gas barrier coating layer / adhesive layer / second substrate Printed layer / first substrate / gas barrier coating layer / adhesive layer / second substrate Furthermore, a coating layer that imparts functions such as heat resistance, releasability, and antistatic properties may be provided on the first substrate.

[0066] (Packaging Material) The gas barrier laminate film of the present invention can be used as a multilayer packaging material for the purpose of protecting foods, medicines, etc. When used as a multilayer packaging material, the layer structure can be changed depending on the contents, usage environment, and usage form. In addition, the packaging body of the present invention may be appropriately provided with an easy-open treatment or a resealable means.

[0067] Taking a laminate having a sealant layer as an example of the packaging material of the present invention, the laminates are stacked with the sealant layer surfaces facing each other, and then the peripheral edges are heat-sealed to form a bag. Examples of bag-making methods include folding or stacking the laminate of the present invention so that the inner layer surfaces (sealant layer surfaces) face each other, and heat-sealing the peripheral edges using, for example, a side seal, two-sided seal, three-sided seal, four-sided seal, envelope seal, flared seal, flat-bottom seal, square-bottom seal, gusset seal, or other heat seal methods. The packaging material of the present invention can take various forms depending on the contents, usage environment, and usage pattern. Self-standing packaging materials (standing pouches) are also possible. Heat sealing can be performed using known methods such as bar seal, rotary roll seal, belt seal, impulse seal, high-frequency seal, and ultrasonic seal.

[0068] When the first substrate and the second substrate of the laminate of the present invention do not function as a sealant layer that serves as a heat-sealed portion when forming a packaging material, a further sealant layer may be added. The sealant layer may be an additional substrate bonded with the adhesive of the present invention, or may be an adhesive layer made of the adhesive of the present invention.

[0069] The packaging material of the present invention is filled with contents through its opening, and then the opening is heat-sealed to produce a product using the packaging material of the present invention. Examples of contents to be filled include foods such as rice crackers, bean snacks, nuts, biscuits, cookies, wafer snacks, marshmallows, pies, semi-dried cakes, candies, and snacks; staple foods such as bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged cooked rice, porridge, rice porridge, packaged rice cakes, and cereal foods; processed agricultural products such as pickles, boiled beans, natto, miso, frozen tofu, tofu, nametake mushrooms, konjac, processed wild vegetables, jams, peanut cream, salads, frozen vegetables, and processed potatoes; processed livestock products such as ham, bacon, sausages, processed chicken, and corned beef; and processed fish ham and meat products. Examples of such foods include processed seafood products such as sausages, fish paste products, kamaboko, nori seaweed, tsukudani (simmered foods in soy sauce), bonito flakes, salted fish, smoked salmon, and spicy mentaiko; fruit pulp such as peaches, mandarin oranges, pineapples, apples, pears, and cherries; vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes; cooked foods such as frozen and chilled prepared dishes, including hamburgers, meatballs, fried seafood, gyoza, and croquettes; dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula; liquid seasonings, retort curry, and pet food.

[0070] In addition, the present invention can also be used as a packaging material for various non-food products, such as cigarettes, disposable body warmers, medicines such as infusion packs, liquid laundry detergent, liquid kitchen detergent, liquid bath detergent, liquid bath soap, liquid shampoo, liquid conditioner, cosmetics such as lotion and emulsion, vacuum insulation materials, batteries, etc.

[0071] (Recycled Plastics, Separation and Recovery Method) The gas barrier laminate film of the present invention can be recycled by known processing methods for recycling waste plastics.

[0072] The recycled plastic of the present invention can be obtained by a known processing method for recycling waste plastics. An example of the processing method is shown below. Of course, the present invention is not limited to this, and various known recycled plastic processing methods can be applied.

[0073] An example of a processing method is a method for producing recycled plastics, which includes the steps of crushing the gas barrier laminate film of the present invention, melt-kneading the crushed pieces, and pelletizing the melt-kneaded mixture. The crusher used in the crushing step of the gas barrier laminate film of the present invention may be any known crusher, and is not particularly limited. The crushed film pieces are physically blended using melt-kneading, solvent cast blending, latex blending, polymer complexing, or the like. Melt-kneading is particularly common. Examples of kneading devices include tumblers, Henschel mixers, rotary mixers, super mixers, ribbon tumblers, and V-blenders. The film is melt-kneaded using such a kneading device and then pelletized. A single-screw or multi-screw extruder is typically used for melt-kneading and pelletizing, and the film pieces may be introduced as is or may be subjected to compression and volume reduction treatment with or without heating before being introduced. In addition to these extruders, a Banbury mixer, a roller, a Co-kneader, a blast mill, a Prabender Bloutograph, etc. may also be used, which are operated batchwise or continuously. Alternatively, the resin may be used as a molding resin and melt-kneaded in the heating barrel of a molding machine without being melt-kneaded.

[0074] Another example of the processing method is a method for producing recycled plastics, which includes the steps of crushing the gas barrier laminate film of the present invention as necessary, immersing the laminate in a stripping liquid to separate and detach each layer, recovering each separated and detached layer, melting and kneading the recovered crushed pieces, and pelletizing the melted and kneaded mixture.

[0075] As described above, the crusher used in the process of crushing the gas barrier laminate film of the present invention may be a known crusher and is not particularly limited. The crushed film pieces are immersed in a release liquid to separate and detach the laminate into individual layers. The separation and detachment method (also simply referred to as a detachment method) is a method in which the gas barrier laminate film of the present invention is immersed in a release liquid (release treatment liquid) to detach other layers provided on the substrate from the substrate. Note that detachment refers to the separation of the substrate from other layers by the detachment layer being dissolved or swelled by the release treatment liquid and peeled off.

[0076] (Removal Treatment Liquid) The release treatment liquid may be any liquid capable of swelling and dissolving the adhesive layer, the printed layer, etc. in the gas barrier laminate film of the present invention, and may be appropriately selected in consideration of the ease of release of the release layer described below. Examples of such release liquids include water, an alkaline solution, and an acidic aqueous solution. From the viewpoint of releasing the materials of the adhesive layer and the printed layer that are commonly used in packaging materials, the release treatment liquid is preferably an alkaline solution containing an inorganic base.

[0077] (Inorganic Base) Specific examples of the inorganic base include sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium dihydrogen carbonate, and potassium dihydrogen carbonate. These inorganic bases are contained in a concentration of 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total weight of the aqueous solution. The pH is preferably 9 or higher, and more preferably 10 or higher.

[0078] (Surfactant) The desorption treatment solution may contain a surfactant. The surfactant is not particularly limited, and known surfactants can be used, such as anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Among these, anionic surfactants, nonionic surfactants, and amphoteric surfactants are preferred.

[0079] Examples of anionic surfactants include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate ester salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates. Specific examples of these include dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, and dibutylphenylphenol disulfonate.

[0080] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylolamides, alkylalkanolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers. Of these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers are preferred.

[0081] Other surfactants that can be used include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; and biosurfactants such as spiculisporic acid, rhamnolipid, and lysolecithin.

[0082] These surfactants can be used alone or in combination of two or more. When a surfactant is added, the amount added is preferably in the range of 0.001 to 2 mass %, more preferably 0.001 to 1.5 mass %, and even more preferably 0.01 to 1 mass %, based on the total amount of the desorption treatment solution.

[0083] (Water-soluble organic solvent) The desorption treatment liquid may contain a water-soluble organic solvent. Examples of the water-soluble organic solvent include water-soluble alcohol and water-soluble glycol ether-based organic solvents. Specific examples include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol dibutyl ether, diethylene glycol monomethyl ether (methyl carbitol), diethylene glycol dimethyl ether, diethylene glycol monoethyl ether (carbitol), diethylene glycol diethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monomethyl ether (methyl carbitol), diethylene glycol mono ...methyl carbitol), diethylene glycol monoethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monomethyl ether (methyl carbitol), diethylene glycol monoethyl ether (methyl carbitol), diethylene glycol monoethyl ether (diethyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol), diethylene glycol monoethyl ether (butyl carbitol Examples include methyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methylene dimethyl ether (methylal), propylene glycol monobutyl ether, tetrahydrofuran, acetone, diacetone alcohol, acetonyl acetone, acetyl acetone, ethylene glycol monomethyl ether acetate (methyl cellosolve acetate), diethylene glycol monomethyl ether acetate (methyl carbitol acetate), diethylene glycol monoethyl ether acetate (carbitol acetate), ethyl hydroxyisobutyrate, and ethyl lactate, which can be used alone or in combination of two or more.

[0084] The content of the water-soluble organic solvent in the desorption treatment liquid is preferably 0.1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass.

[0085] (Non-Water-Soluble Organic Solvent) The desorption treatment liquid may contain a non-water-soluble organic solvent. Specific examples of the non-water-soluble organic solvent include alcohol-based solvents such as n-butanol, 2-butanol, isobutanol, and octanol; aliphatic hydrocarbon-based solvents such as hexane, heptane, and normal paraffin; aromatic hydrocarbon-based solvents such as benzene, toluene, xylene, and alkylbenzene; halogenated hydrocarbon-based solvents such as methylene chloride, 1-chlorobutane, 2-chlorobutane, 3-chlorobutane, and carbon tetrachloride; ester-based solvents such as methyl acetate, ethyl acetate, and butyl acetate; ketone-based solvents such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone; and ether-based solvents such as ethyl ether and butyl ether. These may be used alone or in combination of two or more.

[0086] (Antifoaming Agent) The desorption treatment liquid may contain an antifoaming agent. When stirring or crushing the substrate during immersion, a large amount of foam may be generated, and if the foam remains, the foam may overflow during the plastic film recovery process. Furthermore, if a large amount of foam is entrained in the desorption treatment liquid during crushing of the substrate, the substrate may not be crushed to the desired size.

[0087] Compounds commonly used as defoaming agents include water-soluble organic solvents and nonionic surfactants with low HLB values ​​in the range of 1 to 3, but silicone compounds are particularly preferred because of their high defoaming ability, with emulsion-type and self-emulsifying silicone compounds being particularly preferred.

[0088] The amount of the defoaming agent in the cleaning solution usable in step 1 is preferably in the range of 0.01 to 5% by weight, more preferably in the range of 0.02 to 4% by weight, and even more preferably in the range of 0.03 to 3% by weight.

[0089] (Liquid Temperature) The liquid temperature of the desorption treatment liquid is not particularly limited as long as it can maintain a liquid state, but it is usually preferable to perform the treatment at a liquid temperature of 15 to 90°C. When using a desorption treatment liquid in which a surfactant or the like has been added to water, it is preferable to adjust the liquid temperature depending on the type of surfactant. The optimal temperature for excellent cleaning effectiveness varies depending on the type of surfactant, but is preferably 40°C or higher, preferably 65°C or higher, and preferably 85°C or higher. It is also preferable to immerse the target printed matter or laminate in the desorption treatment liquid, for example, in a treatment tank, while the liquid is heated or ultrasonically vibrated to the above temperature. The heating method is not particularly limited, and known heating methods such as heat rays, infrared rays, and microwaves can be used. Ultrasonic vibration can be used, for example, by attaching an ultrasonic vibrator to the treatment tank and applying ultrasonic vibration to the warm water or alkaline solution.

[0090] (Agitation) Agitation is not essential when the printed material or laminate is immersed in the release treatment solution, but agitation allows for more efficient swelling. It is preferable to keep the agitation speed at a level that does not cause foaming or the like even without adding an antifoaming agent.

[0091] The equipment and method for stirring are not particularly limited, and known methods can be used. Specific examples include an apparatus equipped with a motor with stirring blades that can stir the cleaning solution in a container, an apparatus equipped with a device that generates ultrasonic waves, an apparatus that can shake the entire container, a wet crusher, a water jet stirring method using a water jet pump, and a bubbling method using an inert gas such as nitrogen gas.

[0092] The time for immersing the printed matter or laminate in the desorption treatment solution varies depending on the configuration of the printed matter or laminate, but is generally in the range of 2 minutes to 48 hours. Note that in the printed matter or laminate, it is not necessary for 100% of the coating such as the printed layer to be completely detached from the substrate, but it is preferable that 60% by mass or more of 100% by mass of the coating be detached, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0093] In the detachment step, the immersion in the detachment treatment solution may be performed once or several times. That is, the immersion may be performed once, followed by a step of recovering the separated film substrate, or the immersion may be performed several times, followed by a step of recovering the film substrate. When immersion is performed multiple times in the detachment step, the concentration of the detachment treatment solution may be changed. Furthermore, known steps such as washing with water and drying may be added as appropriate during the detachment step.

[0094] The detachment treatment liquid also promotes detachment of the plastic substrate by contacting the printed layer, primer layer, or the interface between the substrate and another layer from the edge of the printed matter or laminate. Therefore, it is preferable that the printed layer, adhesive layer, or primer layer is exposed on the cross section. Therefore, it is more preferable to include a step of fragmenting the printed matter or laminate by cutting or pulverizing.

[0095] The method for crushing the plastic film is not particularly limited, and can be performed by a known method. Crushing may be performed in an air atmosphere in the absence of a liquid such as a solvent, or in water or a cleaning solution. When crushing in an air atmosphere, a dry crusher can be used. When crushing in water or a cleaning solution, a wet crusher can be used, which can crush and pressure-feed simultaneously. When a wet crusher is used, the plastic film can be efficiently crushed, and the laminated plastic film can be peeled into each layer.

[0096] After the immersion treatment in the release treatment liquid described above, it is preferable to provide a step of stirring the recovered substrate in water or in the release treatment liquid described above. This step increases the rate at which a coating such as a printed layer is detached from the substrate. The equipment and method for stirring are not particularly limited, and known methods can be used, but stirring is preferably performed using a wet crusher.

[0097] Furthermore, it is preferable to agitate the recovered substrate in a rinse solution for finish cleaning to remove any ink, adhesive, or other detached material that re-adheres to the plastic film that has been detached as a single layer. Removing even traces of ink remaining on the film surface significantly improves the quality of the recycled pellets. The rinse solution is not particularly limited, and the aforementioned detachment treatment solution can be used as is. However, it is preferable for the rinse solution to contain an appropriate amount of organic solvent. The organic solvent preferably contains, for example, one or more water-soluble alcohols or water-soluble solvents with a flash point of 21°C or higher. It is preferable for the cleaning solution to contain a large amount of so-called water-soluble solvents, including alcohols. Specifically, the water-soluble solvent is preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 95% by mass or more. The equipment and method for agitating the substrate in the rinse solution are not particularly limited, and known methods can be used. Specific examples include a device equipped with a motor with stirring blades that can stir the cleaning liquid in a container, a device equipped with a device that generates ultrasonic waves, a device that can shake the entire container, a wet crusher, a kneader, etc.

[0098] (Recovery and reuse of desorption treatment liquid) The desorption treatment liquid used in the desorption treatment step can be recycled after being recovered by supplying it to one or more recycling machines selected from a filter, a centrifuge, and an ultrafilter, and removing solids. Water, a rinse liquid, etc. can also be recycled in the same way. While wet crushing is being performed, the recycling process of water, desorption treatment liquid, rinse liquid, etc. can be continuously operated to separate solids from the water, washing liquid, and rinse liquid.

[0099] (Drying of Separated Plastics) The separated and recovered substrate material is dried (film fragments) by one or more methods selected from reduced pressure heating drying, hot air drying, pressurized compression drying, etc. to remove residual moisture. As a pretreatment for producing recycled pellets (described below), after or during drying of the recovered film fragments, briquettes may be produced using a pressurized compressor such as a Nippon Seam compression dehydrator, a Oike Iron Works pellet mill, or an Elcom Stella or briquette machine. When plastic film is pulverized into powder using a wet grinder, the crushed material is pulverized to approximately 10 to 500 μm. Since the crushed material has a high density, the pressurized compression step can be omitted. The density varies depending on the material constituting the crushed material, but a higher density is preferable because it is easier to handle when passing it through a kneader. Specifically, a dry weight of 0.03 kg or more is preferred, 0.05 kg or more is more preferred, 0.2 kg or more is more preferred, and 0.3 kg or more is even more preferred.

[0100] The pellets of the present invention, primarily made from recycled plastic, can maximize their effectiveness by being recycled into unstretched polyolefin films or molded products, such as injection molding. The method for recycling the recycled plastic into unstretched polyolefin films is not particularly limited, and can be produced using known film production methods. Examples include melt-mixing using common mixers such as single-screw extruders, twin-screw extruders, and multi-screw extruders, and methods in which the components are dissolved or dispersed and mixed and then the solvent is removed by heating. Considering workability, the use of a single-screw extruder or twin-screw extruder is particularly preferred. When using a single-screw extruder, any type of extruder can be used, including full-flighted screws, screws with mixing elements, barrier-flighted screws, and fluted screws, without any particular limitations. Twin-screw extruders include co-rotating twin-screw extruders and counter-rotating twin-screw extruders, and the screw configurations are not particularly limited, including full-flighted screws and kneading disk types. Alternatively, the extruder may be melted using a single-screw or twin-screw extruder, and then passed through a feed block or multi-manifold to form a film using a T-die. Furthermore, if necessary, the recycled film can be subjected to a surface modification treatment to appropriately improve its suitability for subsequent processes. For example, to improve printability when used as a standalone film or lamination suitability when used in a laminated structure, a surface modification treatment can be performed on the surface that comes into contact with other substrates. Suitable surface modification treatments include corona discharge treatment, plasma treatment, flame treatment, and other methods that oxidize the film surface to develop functional groups, as well as wet process methods such as coating with an easy-adhesion layer.

[0101] In addition, in the same manner as with pellets made primarily from virgin plastics, the plastic may be molded into a molded article by a conventional molding method other than the above-mentioned film formation, such as injection molding, extrusion molding, vacuum molding, pressure molding, blow molding, or the like, and used for various purposes. For example, it can be used as daily necessities, stationery, toys, sporting goods, home appliances, and automobile parts used in ordinary households, as well as films, sheets, and fibers. If there are no hygiene issues, it can also be used in medical devices, food containers, and food packaging materials.

[0102] The present invention will be described in more detail below with reference to specific examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0103] <Substrate> MDOPE1 in the examples and comparative examples is a uniaxially stretched high-density polyethylene film having a surface energy of 52 mN / m or more and a thickness of 25 μm. MDOPE2 in the examples and comparative examples is a uniaxially stretched low-density polyethylene film having a surface energy of 38 mN / m and a thickness of 23 μm. MDOPE3 in the examples and comparative examples is a uniaxially stretched high-density polyethylene film having a surface energy of 42 mN / m and a thickness of 26 μm. BOPE in the examples and comparative examples is a biaxially stretched high-density polyethylene film having a surface energy of 41 mN / m and a thickness of 24 μm. OPP1 in the examples and comparative examples is a biaxially stretched polypropylene film having a surface energy of 38 mN / m and a thickness of 20 μm. OPP2 in the examples and comparative examples is a biaxially stretched polypropylene film having a surface energy of 42 mN / m and a thickness of 20 μm.

[0104] <Preparation of Coating Agent (A)> (Coating Agent A1) A heat-resistant coating agent containing 88% cellulose propionate with a Tg of 159°C in terms of solid content and 10% non-volatile content was prepared as Coating Agent A1. (Coating Agent A2) A surface coating agent containing a vinyl chloride-vinyl acetate copolymer with a Tg of 75°C and a urethane resin was prepared as Coating Agent A2. (Coating Agent A3) A surface coating agent containing a vinyl chloride-vinyl acetate copolymer with a Tg of 75°C and a polyester resin was prepared as Coating Agent A3.

[0105] <Preparation of Coating Agent (B)> (Coating Agent B1) 10 parts of isopropyl alcohol (hereinafter referred to as IPA) was added to 90 parts of a solution of Kuraray Poval 60-98 (Kuraray Co., Ltd., fully saponified polyvinyl alcohol resin) in water to a non-volatile content of 5%, to prepare Coating Agent B1. (Coating Agent B2) 1 part of Epomin P-1000 (Nippon Shokubai, polyethyleneimine aqueous solution) and 10 parts of IPA were added to 89 parts of a solution of Kuraray Poval 60-98 (Kuraray Co., Ltd., fully saponified polyvinyl alcohol resin) in water to a non-volatile content of 5%, to prepare Coating Agent B2. (Coating agent B3) 95 parts of Gohsenex Z-100 (manufactured by Mitsubishi Chemical Corporation, modified polyvinyl alcohol resin) dissolved in water to a non-volatile content of 10% was added to 5 parts of ADH (manufactured by Otsuka Chemical Co., Ltd., adipic acid dihydrazide) dissolved in a water / IPA mixed solvent to a non-volatile content of 5%, and the mixture was mixed to prepare coating agent B3.

[0106] <Method of applying coating agent (B) layer> Coating agents B1 to B3 are applied using a bar coater in an amount of 0.3 to 0.5 g / m ２ (solid content), and then dried in a dryer set at a temperature of 70°C to volatilize the dilution solvent.

[0107] <Coating method for printed layer> Gravure ink Glosser 709 White Y3 manufactured by DIC Corporation was applied to the coated surface of the coating agent (B) layer of the laminate prepared by the above "Coating method for coating agent (B) layer" or directly to the substrate using a gravure coater and a gravure plate with Helio 175 lines / inch, and the diluted solvent was evaporated and dried in a dryer set at a temperature of 70°C. The coating amount of the printed layer was 1.4 g / m ２ It was.

[0108] <Coating method for coating agent (A) layer> Coating agents A1 to A3 were applied to the printed layer coated surface of the laminate having the printed layer prepared by the above "Coating method for printed layer" or directly to the substrate using a gravure coater with a gravure plate of Helio 175 lines / inch, and the diluted solvent was evaporated and dried in a dryer set at a temperature of 70°C, and then the laminate was cured at 40°C for 2 days. The coating amount of the coating agent (A) layer was 0.5 to 0.7 g / m ２ It was.

[0109] By combining the above coating methods, gas barrier laminate films of Examples 1 to 18 and Comparative Examples 1 to 25 were obtained. The structures are shown in Tables 1 to 5.

[0110] <Evaluation Method> (Oxygen Barrier Property) The gas barrier laminate films of the Examples and Comparative Examples were cut to a size of 10 cm x 10 cm, and the oxygen permeability was measured in accordance with JIS-K7126 (constant pressure method) using an OX-TRAN2 / 21 (oxygen permeability measuring device manufactured by Mocon) under an atmosphere of 23°C, 0% RH, and 23°C, 50% RH (unit: cc / m2 / day / atm). RH represents humidity. The oxygen permeability evaluation criteria were as follows: ○: 10 or less at both 0% and 50%, △: 10-50 at both 0% and 50%, ×: 50 or more at both 0% and 50%, or at least one of them.

[0111] (Water Resistance) A drop of ion-exchanged water was dropped on the outermost surface of the gas barrier laminate film of each of the Examples and Comparative Examples, and after one minute it was wiped off. The coating surface was visually observed and evaluated on a three-point scale: ○: No change in the coating surface; △: The coating surface was discolored; ×: The coating was dissolved.

[0112] (Adhesion to substrate) Cellophane tape (TF-12 manufactured by Nichiban Co., Ltd.) was applied to the outermost surface of the gas barrier laminate film of each of the Examples and Comparative Examples, and the degree of peeling when the tape was peeled off in one go was visually judged and rated on a 5-point scale: 5: No peeling; 4: Less than 20% peeling; 3: 20 to less than 70% peeling; 2: 70% or more peeling; 1: Complete peeling

[0113] (Heat seal heat resistance (evaluation of whether film shrinkage occurs)) The gas barrier laminate films of the Examples and Comparative Examples were brought into contact with a heat seal bar so that it directly touched the outermost surface of the laminate using a thermal gradient heat seal tester (manufactured by Tester Sangyo Co., Ltd.) at a sealing temperature of 100°C to 160°C, a pressure of 3 kg / cm2, and a time of 1 second. The presence or absence of shrinkage of the laminate around the sealed area where the heat seal bar came into contact was visually confirmed. The temperature difference at which the laminate was able to suppress shrinkage was recorded to determine how much the temperature difference was improved compared to a film uncoated with coating agent (A), ink, and coating agent (B). If there was no difference in temperature, it was recorded as "no effect."

[0114] (Deinking Property) The gas barrier laminate films of the Examples and Comparative Examples were cut into 15 mm x 15 mm test pieces. The test pieces were immersed in a treatment liquid (2% aqueous NaOH solution) at 80°C and stirred at 800 rpm for 10 minutes using a magnetic stirrer, after which the test pieces were removed. After washing with ion-exchanged water and drying, the peeled area (%) of coating agent (A), ink, and coating agent (B) was measured and evaluated according to the following criteria, with the results summarized in the table. 5: Complete peeling (coating agent (A), ink, and coating agent (B) completely peeled from the film) 4: 90% or more but less than 100% peeling 3: 50% or more but less than 90% peeling 2: 10% or more but less than 50% peeling 1: Less than 10% peeling

[0115] The structures and results of the gas barrier laminate films of Examples 1 to 18 are shown in Tables 1 and 2. Note that blank spaces indicate that the respective layers were not used.

[0116]

[0117]

[0118] The structures and results of the gas barrier laminate films of Comparative Examples 1 to 25 are shown in Tables 3 to 5.

[0119]

[0120]

[0121]

[0122] As a result, it is clear that the gas barrier laminate films of the examples can be used to produce packaging materials with excellent functions such as oxygen barrier properties, water resistance, adhesion, and heat resistance, and also have deinking properties that are suitable for recycling.

Claims

1. A gas barrier laminate film characterized by comprising an olefin resin film and a print layer or a surface coating layer, and a resin layer containing a vinyl alcohol polymer provided between the olefin resin film and the print layer or surface coating layer.

2. The gas barrier laminate film according to claim 1, which comprises a resin layer containing a vinyl alcohol polymer and a polyalkyleneimine or hydrazide between the olefin resin film and the print layer or surface coat layer.

3. The gas barrier laminate film according to claim 1, wherein the olefin resin film is a polyethylene resin film.

4. The gas barrier laminate film according to claim 1, wherein the surface coating layer contains a polymer compound having a glass transition temperature of 70° C. or higher.

5. A packaging material using the gas barrier laminate film according to any one of claims 1 to 4.

6. Recycled plastic using the gas barrier laminate film according to any one of claims 1 to 4.

7. A method for separating and recovering the gas barrier laminate film according to any one of claims 1 to 4, comprising the steps of immersing the film in a stripping solution and recovering each layer that has been separated and detached.

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