Laminate, packaging material, and recycling method

Abstract

To provide a laminate in which a printed layer and an adhesive layer are easily peeled off when immersed in a release agent, and adhesive layer pieces and printed layer pieces peeled off from the laminate are not too fine and can be easily recovered from the release agent, a method for recycling the laminate, and recycled plastics obtained from the laminate. A laminate comprising a first substrate, a second substrate, a release layer disposed between the first substrate and the second substrate, an adhesive layer disposed between the release layer and the second substrate and being a cured coating film of an adhesive containing an acid anhydride, and a printed layer disposed between the release layer and the adhesive layer.

Description

[Technical Field]

[0001] The present invention relates to a laminate with excellent recyclability, a packaging material using the laminate, and a method for recycling the laminate and the packaging material. [Background technology]

[0002] Laminates used in various packaging materials, labels, etc. are provided with design, functionality, storage stability, convenience, and transportability by laminating a wide variety of substrates such as plastic films, metal foils, and paper, and in particular, packages obtained by molding such laminates into bags are used as packages for foods, medicines, detergents, etc. Two-component adhesives that combine a polyisocyanate composition and a polyol composition are widely known as adhesives used to bond these substrates together.

[0003] In recent years, the recycling of packaging materials made of such laminates has been actively studied. Generally, a method is known in which waste plastics containing a mixture of thermoplastic resins and thermosetting resins are separated by specific gravity for recycling, but separation is difficult when the materials are bonded together with adhesive. For this reason, studies have been conducted on peeling the laminates with a peeling agent such as an alkaline aqueous solution (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-131484 [Patent Document 2] Japanese Patent Application Publication No. 11-209677 Summary of the Invention [Problem to be solved by the invention]

[0005] The release agent used to peel the laminate is preferably recovered and reused after removing components other than film fragments, such as adhesive layer fragments and printed layer fragments, peeled from the laminate. Filtration, for example, can be used to remove components other than film fragments. Components such as adhesive layer fragments and printed layer fragments can be reduced in size by shear forces applied by stirring, which is often performed during the laminate peeling process. If the adhesive layer fragments and printed layer fragments are reduced in size too much during the peeling process, they may not be able to be filtered out completely depending on the filter opening size, and the adhesive layer fragments and printed layer fragments may remain in the filtered release agent, causing discoloration of the release agent. If a filter with a small opening size is used to suppress discoloration of the release agent after filtration, filtration will take a long time.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a laminate in which the printed layer and adhesive layer are easily peeled off when immersed in a release agent, and in which the adhesive layer pieces and printed layer pieces peeled off from the laminate do not become too fine and are easy to recover from the release agent, a method for recycling the laminate, and recycled plastics obtainable from the laminate. [Means for solving the problem]

[0007] The present invention relates to a laminate comprising a first substrate, a second substrate, a release layer disposed between the first substrate and the second substrate, an adhesive layer disposed between the release layer and the second substrate and being a cured coating film of an adhesive containing an acid anhydride, and a printed layer disposed between the release layer and the adhesive layer. [Effects of the Invention]

[0008] According to the present invention, a laminate can be obtained in which the printed layer and adhesive layer are easily peeled off when immersed in a release agent, and the adhesive layer pieces and printed layer pieces peeled off from the laminate do not become too fine and can be easily recovered from the release agent. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Laminate> The laminate of the present invention includes a first substrate, a second substrate, a release layer, an adhesive layer, and a printing layer. The laminate of the present invention will be described in detail below.

[0010] (First substrate) The first substrate can be any film or sheet (unless otherwise specified below, "film" is a general term for both films and sheets) that has excellent chemical and physical strength. Examples of the first substrate include polyethylene terephthalate (PET) film, polystyrene film, polyamide film, polyacrylonitrile film, polyethylene film (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film, MDOPE: uniaxially oriented polyethylene film, OPE: biaxially oriented polyethylene film), polypropylene film (CPP: unoriented polypropylene film, OPP: biaxially oriented polypropylene film), polyolefin film such as a gas barrier film in which an olefin-based heat-sealable resin layer is provided on one or both sides of a resin having gas barrier properties such as an ethylene-vinyl alcohol copolymer or polyvinyl alcohol, polyvinyl alcohol film, ethylene-vinyl alcohol copolymer film, and the like.

[0011] It is also preferable to use a film made of a material containing biomass-derived components. 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.

[0012] 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.

[0013] Alternatively, products made from biomass materials are also available, classified by their biomass plastic content as specified by ISO 16620 or ASTM D6866. Radioactive carbon-14C exists in the atmosphere at a rate of 1 in 1012 particles, and this rate remains 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, or biomass plastic content, can be determined. Examples of plant-derived low-density polyethylene that 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.

[0014] The film may be one that has been subjected to a stretching treatment. A typical stretching method involves melt-extruding a resin into a sheet using an extrusion film-forming method or the like, followed by simultaneous biaxial stretching or sequential biaxial stretching. In the case of sequential biaxial stretching, it is common to first perform longitudinal stretching and then transverse stretching. Specifically, a method that combines longitudinal stretching utilizing the speed difference between rolls and transverse stretching using a tenter is often used.

[0015] The film surface may be subjected to various surface treatments such as flame treatment and corona discharge treatment as necessary so that an adhesive layer without defects such as film breakage or repellency is formed.

[0016] Alternatively, inorganic vapor-deposited films such as metal-deposited films with a vapor-deposited layer of a metal such as aluminum, transparent vapor-deposited films with a vapor-deposited layer of a metal oxide such as silica or alumina, or barrier films containing a gas barrier layer such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, or vinylidene chloride may be used. Such films are preferred because, when a basic compound is contained in the stripping solution used to separate the laminate in the recycling process described below, the vapor-deposited layer is easily dissolved in the stripping solution, making it easier to peel the printed layer and adhesive from the resin film.

[0017] The thickness of the first substrate is not particularly limited, and may be appropriately selected in the range of 1 to 300 μm from the viewpoint of formability and transparency, and is preferably in the range of 1 to 100 μm.

[0018] (Second substrate) The second substrate can be the same as the first substrate. In one embodiment of the present invention, the second substrate is a film (sealant film) having heat-sealability that can be melted by heat and fused to each other, and the first substrate is a substrate that is not expected to function as a sealant film. In another embodiment of the present invention, the second substrate is a film in which a film without heat-sealability and a resin layer (heat-seal layer) having heat-sealability are laminated, and the first substrate is a substrate that is not expected to function as a sealant film.

[0019] Examples of heat-sealable resins include polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-ethyl(meth)acrylate copolymer, ethylene-propylene copolymer, methylpentene polymer, modified olefin resins such as polyethylene or polypropylene modified with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids, ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid terpolymers, cyclic polyolefins, cyclic olefin copolymers, polyethylene terephthalate (PET), polyacrylonitrile (PAN), and gas-barrier resins such as ethylene-vinyl alcohol copolymers and polyvinyl alcohol, each of which has an olefin-based heat-sealable resin layer on one or both sides. Films, sheets, and other coatings made of one or more of these resins can be used as sealant films.

[0020] As the sealant film, any of unstretched, uniaxially stretched and biaxially stretched films can be used.

[0021] A biaxially stretched film can be obtained by, for example, longitudinally stretching the film 2 to 4 times using a roll stretching machine at 50 to 100° C., then transversely stretching the film 3 to 5 times using a tenter stretching machine in an atmosphere at 90 to 150° C., and subsequently heat-treating the film using the tenter stretching machine in an atmosphere at 100 to 240° C. Alternatively, a film that has been subjected to simultaneous biaxial stretching or sequential biaxial stretching may also be used.

[0022] An easily peelable sealant film (easy peel film) may be used as the sealant film. Any of the interfacial peeling type, cohesive peeling type, and interlayer peeling type sealant films can be used, and can be appropriately selected depending on the type and required properties of the packaging material described below. The index of easy peelability is appropriately set depending on the type and required properties of the packaging material, and an example is a seal strength of 2 to 20 N / 15 mm. For example, easy peelability can be achieved by a phase-separated polymer blend that combines polypropylene with high-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, or the like.

[0023] When the second substrate is a film laminated with a film that does not have heat-sealing properties and a resin layer (heat-sealing layer) that has heat-sealing properties, the second substrate can be, for example, a film that does not have heat-sealing properties coated with a heat-sealing agent containing a resin that has heat-sealing properties.

[0024] Examples of heat-sealable resins include thermoplastic resins such as shellacs, rosins, rosin-modified maleic acid resins, rosin-modified phenolic resins, nitrocellulose, cellulose acetate, cellulose acetyl propionate, cellulose acetyl butyrate, chlorinated rubber, cyclized rubber, vinyl chloride, vinylidene chloride, polyamide resins, vinyl chloride-vinyl acetate copolymers, polyester resins, ketone resins, butyral resins, chlorinated polypropylene resins, chlorinated polyethylene resins, chlorinated ethylene vinyl acetate resins, ethylene vinyl acetate resins, acrylic resins, urethane resins, ethylene-vinyl alcohol resins, styrene-maleic acid resins, casein, and alkyd resins, and these may be used alone or in combination of two or more.

[0025] The heat sealing agent may be in any form, such as a type in which these resins are dissolved in an organic solvent, a type in which these resins are dissolved in water or an aqueous organic solvent, or an emulsion type in which an acrylic emulsion, a urethane emulsion, a polyvinyl alcohol resin, an ethylene-vinyl alcohol emulsion, an ethylene-methacrylic acid emulsion, a polyolefin emulsion, an ethylene vinyl acetate emulsion, or the like is dispersed in water or an aqueous organic solvent.

[0026] The organic solvent is not particularly limited, and examples thereof include various organic solvents such as aromatic hydrocarbons such as toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; and esters such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate.

[0027] Examples of aqueous organic solvents include alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; and glycol ethers such as ethylene glycol (mono, di)methyl ether, ethylene glycol (mono, di)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di)methyl ether, diethylene glycol (mono, di)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di)methyl ether, propylene glycol (mono, di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di)methyl ether.

[0028] The heat-sealing agent may contain components other than the heat-sealable resin and solvent, such as wax, filler, antifoaming agent, viscosity modifier, leveling agent, tackifier, preservative, antibacterial agent, rust inhibitor, antioxidant, etc.

[0029] The heat sealing agent can be applied by any known method, such as a roll coater, gravure coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, curtain coater, cast coater, spray coater, die coater, offset printing machine, screen printing machine, etc. After coating, a drying step in an oven or the like can be performed.

[0030] The thickness of the heat seal layer (the amount of heat sealant applied (solid content)) may be any thickness. For example, it is 0.5 g / m 2 ~5g / m 2 is.

[0031] The thickness of the second substrate can be selected arbitrarily, but when applied to a packaging material as described below, it is selected in the range of 5 to 500 μm, more preferably 10 to 250 μm, and even more preferably 15 to 100 μm.

[0032] The second substrate may have a vapor-deposited metal layer such as aluminum or a vapor-deposited inorganic layer such as aluminum oxide or silica.

[0033] (detachment layer) The release layer is disposed on the surface of the first substrate facing the second substrate, and is a layer that is released from the first substrate when the laminate of the present invention is immersed in a release agent described below for a certain period of time. The release layer in the laminate of the present invention is not particularly limited as long as it has this function, but examples include the following embodiments.

[0034] (Detachment layer (1)) An embodiment of the release layer in the laminate of the present invention includes a layer containing a vinyl alcohol polymer and a polyalkyleneimine. Such a release layer (1) can be formed, for example, by applying a coating agent containing a vinyl alcohol polymer, a polyalkyleneimine, and an aqueous solvent to the first substrate and then drying the solvent.

[0035] The vinyl alcohol polymer is a hydrolyzate of a vinyl ester homopolymer or copolymer and can be obtained by a known, commonly used method, or the vinyl alcohol polymer is a reaction product of a hydrolyzate of a vinyl ester homopolymer or copolymer with an aldehyde and can be obtained by a known, commonly used method.

[0036] 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.

[0037] 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 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, it is preferable to use at least one selected from ethylene, propene, isopropenyl acetate, 2-propenyl acetate, 3,4-diacetoxy-1-butene, and 2,2-dialkyl-4-vinyl-1,3-dioxolane.

[0038] When a vinyl ester and a polymerizable compound are used in combination, the amounts used can be adjusted as appropriate. For example, the amount of the polymerizable compound blended is 1 mol % to 40 mol %, as another example, 1 mol % to 20 mol %, and as another example, 1 mol % to 15 mol % of the total amount of the vinyl ester and the polymerizable compound.

[0039] The vinyl alcohol polymer may be acetalized. Examples of the aldehyde 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 such aldehydes 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 singly or in combination of two or more.

[0040] 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.

[0041] The weight average molecular weight of the vinyl alcohol polymer is, for example, 3,000 to 500,000, more preferably 5,000 to 100,000, and even more preferably 10,000 to 80,000.

[0042] It is preferable to use a vinyl alcohol polymer that can be dissolved at 5% by mass or more in a 1:1 (mass ratio) solution of water and ethanol at 25°C, and that has a viscosity of 200 mPa·s or less at 25°C when a 5% by mass solution of the vinyl alcohol polymer is dissolved in a 1:1 (mass ratio) solution of water and ethanol. If a vinyl alcohol polymer is dissolved in a 1:1 (mass ratio) solution of water and ethanol and left to stand for one day at 25°C, and no precipitate or gel-like material is found, the vinyl alcohol polymer is considered to have dissolved.

[0043] While vinyl alcohol-based polymers have excellent solubility in water, many have low solubility in low-molecular-weight alcohols such as ethanol, and such vinyl alcohol-based polymers are only slightly soluble in a cosolvent of water and ethanol. By selecting and using a polymer with excellent solubility in a cosolvent of water and ethanol, the coating agent used to form the release layer can be made to have excellent coating suitability even at high solids contents, allowing for the efficient formation of a coating film of appropriate thickness as the release layer. Furthermore, less energy is required to volatilize the solvent from the coating agent during the formation of the release layer, thereby reducing the environmental impact. The solubility of a vinyl alcohol-based polymer in low-molecular-weight alcohols can be adjusted, for example, by incorporating a skeleton that increases alcohol solubility into the main chain using ethylene or propylene with a vinyl ester, or by using 3,4-diacetoxy-1-butene with a vinyl ester to introduce hydroxyl groups into the side chain, or by adjusting the molecular weight, butyralization, and saponification degree of the vinyl alcohol-based polymer. The saponification degree of the vinyl alcohol-based polymer can be adjusted as needed, but is typically 90% or higher.

[0044] The polyalkyleneimine is a resin having a polyalkyleneimine skeleton, and can be obtained by polymerizing one or more alkyleneimines (for example, ethyleneimine, propyleneimine) by a conventional method.

[0045] The polyalkyleneimine may be a linear polyalkyleneimine having 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 polyalkyleneimines may be used in combination.

[0046] It is believed that the amino groups (NHR groups, NH2 groups) and ethylene groups of the polyalkyleneimine 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.

[0047] The number average molecular weight of the polyalkyleneimine is, for example, from 5,000 to 100,000. The number average molecular weight of the polyalkyleneimine is measured by GPC (gel permeation chromatography) using pullulan as a standard substance.

[0048] From the viewpoint of the balance between the adhesive strength of the laminate and the prevention of blocking when the release layer (1) is wound up after formation, the amount of polyalkylimine in the release layer (1) is preferably 1% by mass or more and 25% by mass or less of the total amount of the vinyl alcohol polymer and the polyalkylimine.

[0049] The release layer (1) may contain a resin other than a vinyl alcohol polymer or polyalkylimine. Examples of such resins include cellulose resin, polyester, polyurethane, vinyl resins such as homopolymers or copolymers of olefins or styrene, acrylic resin, epoxy resin, amide resin, natural rubber, and composites thereof (e.g., core-shell resins). The content of these resins is preferably kept to 10% by mass or less of the total amount of the vinyl alcohol polymer and polyalkyleneimine. More preferably, it is 5% by mass or less, and even more preferably, it is 1% by mass or less. It may even be 0% by mass.

[0050] The glass transition temperature of the release layer (1) is preferably 40°C or higher and 80°C or lower. This prevents blocking when the substrate is wound up after the release layer (1) is formed, and allows for a laminate with excellent adhesive strength and recyclability. The glass transition temperature of the release layer (1) can be adjusted by the vinyl alcohol polymer and polyalkyleneimine used, their blending ratios, etc. The glass transition temperature of the release layer (1) is more preferably 50°C or higher and more preferably 70°C or lower.

[0051] The aqueous solvent may be water, a water-soluble organic solvent that dissolves in water, or the like. As the water, pure water or ultrapure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, or distilled water may be used. From the viewpoint 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.

[0052] 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.

[0053] The coating agent used to form the release layer (1) may further contain additives such as a crosslinking agent capable of reacting with functional groups possessed by the vinyl alcohol polymer or polyalkylimine, an inorganic filler, an antifoaming agent, a leveling 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.

[0054] 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 suitable isocyanates 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 isocyanates, blocked isocyanates prepared using known blocking agents or emulsion-type isocyanates may be used.

[0055] The use of a crosslinking agent is expected to improve adhesion to an olefin-based substrate. The amount of the crosslinking agent is, for example, 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the total amount of the first vinyl alcohol-based polymer and the first polyalkyleneimine.

[0056] The resin content of the coating agent, including the vinyl alcohol polymer and polyalkyleneimine, can be adjusted appropriately, but is, for example, 7.5% by mass or more. The solid content of the coating agent is not particularly limited, but is adjusted so that the viscosity at 25°C does not exceed 300 mPa s.

[0057] The method for applying the coating agent is not particularly limited, and methods that can be used 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, reverse gravure, flexography, knife coating, and dot coating.

[0058] The thickness of the release layer (1) can be adjusted as appropriate, but is, for example, 0.1 μm or more and 2.0 μm or less.

[0059] (Detachment layer (2)) Another embodiment of the release layer in the laminate of the present invention includes a layer containing a urethane resin having an ester bond. Such a release layer (2) can be formed, for example, by applying a coating agent containing a urethane resin and a solvent to the first substrate and then drying the solvent. The solvent can be either an organic solvent or an aqueous solvent.

[0060] Urethane resins having ester bonds can be obtained by reacting polyester polyol with polyisocyanate, which can be produced by esterification of polycarboxylic acid with polyol.

[0061] Examples of polycarboxylic acids used in the production of polyester polyols include dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-P,P'-dicarboxylic acid, as well as their anhydrides and ester-forming derivatives; aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and their ester-forming derivatives; sulfonic acid group-containing aromatic dicarboxylic acids such as 5-sulfoisophthalic acid and their ester-forming derivatives; aliphatic dicarboxylic acids such as succinic acid, succinic anhydride, adipic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, maleic anhydride, and fumaric acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and their anhydrides and ester-forming derivatives. These may be used alone or in combination of two or more.

[0062] As the polycarboxylic acid, adipic acid is preferably used, and it is preferable that 50 mass % or more of the polycarboxylic acid used in the production of the polyester polyol is adipic acid.

[0063] Examples of polyols used in producing polyester polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, neopentyl glycol, etc. These may be used alone or in combination of two or more.

[0064] It is preferable to use diethylene glycol or ethylene glycol, and it is preferable that 50 mass % or more of the polyol used in the production of the polyester polyol is diethylene glycol or ethylene glycol.

[0065] The polyester polyols are obtained by reacting these polycarboxylic acids with polyols in the presence of a catalyst, if necessary, in a reaction vessel purged with an inert gas such as nitrogen under atmospheric or reduced pressure. The reaction temperature is preferably 100°C to 300°C.

[0066] Examples of the catalyst that can be used include acetates of alkali metals or alkaline earth metals, and compounds containing zinc, manganese, cobalt, antimony, germanium, titanium, tin, zirconium, etc. It is preferable to use tetraalkyl titanates or tin oxalate, which are effective in transesterification reactions and polycondensation reactions.

[0067] Examples of polyisocyanates used in the synthesis of urethane resins having ester bonds include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate, and aliphatic or alicyclic structure-containing diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more. It is preferable to use one or more selected from the group consisting of isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

[0068] The polyisocyanate preferably contains isophorone diisocyanate, and it is preferable that 50% by mass or more of the polyisocyanate is isophorone diisocyanate.

[0069] In the synthesis of a urethane resin having an ester bond, a polyol other than polyester polyol, a polyamine, or water may be used in combination as a chain extender. Examples of polyols other than polyester polyols include glycols such as methylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, neopentyl glycol, sucrose, glycerin, and sorbitol; and phenols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone.

[0070] Examples of polyamines include diamines such as ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, and 1,4-cyclohexanediamine; N-hydroxymethylaminoethylamine, N-hydroxyethylaminoethylamine, N-hydroxypropylaminopropylamine, N-ethylaminoethylamine, and N-methylaminoethylamine; Propylamine; diethylenetriamine, dipropylenetriamine, triethylenetetramine; hydrazine, N,N'-dimethylhydrazine, 1,6-hexamethylenebishydrazine; succinic acid dihydrazide, adipic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide; β-semicarbazidopropionic acid hydrazide, 3-semicarbazido-propyl-carbazic acid ester, semicarbazido-3-semicarbazidomethyl-3,5,5-trimethylcyclohexane, and the like.

[0071] The weight-average molecular weight of the urethane resin is adjusted as appropriate, but is, for example, 10,000 to 100,000. When the urethane resin is dissolved in an organic solvent and applied, the weight-average molecular weight is preferably 20,000 or more and 60,000 or less, and when the urethane resin is dispersed in an aqueous solvent and applied, the weight-average molecular weight is preferably 30,000 or more and 80,000 or less.

[0072] The glass transition temperature of the urethane resin is preferably 0 to 110°C.

[0073] The urethane resin having an ester bond can be obtained by reacting a polyester polyol with a polyisocyanate in the presence of an organic solvent. When a chain extender is used in combination in the synthesis of the urethane resin, the polyester polyol and the polyisocyanate may be reacted together, or the polyester polyol and the polyisocyanate may be reacted together and then the chain extender may be reacted.

[0074] The organic solvent used in the synthesis of the urethane resin may be a ketone such as acetone or methyl ethyl ketone; an ether such as tetrahydrofuran or dioxane; an acetate ester such as ethyl acetate or butyl acetate; a nitrile such as acetonitrile; dimethylformamide, N-methylpyrrolidone, or the like, which may be used alone or in combination of two or more.

[0075] When the solvent contained in the coating agent is an organic solvent (hereinafter also referred to as when the coating agent is solvent-based), from the viewpoint of the balance between the releasability of the release layer (2) and the solubility of the urethane resin in the coating agent, it is preferable to use a urethane resin having an ester bond group concentration of 3 mmol / g to 9 mmol / g and R (HSP distance) represented by the following formula (1) of 9 or less.

[0076]

number

[0077] R (HSP distance) is an index of the solubility of an organic solvent in a polyester polyol, and the lower the value, the better the solubility can be expected. In the present invention, R is 9 or less. R (HSP distance) is preferably 8 or less, and more preferably 7 or less. Furthermore, R (HSP distance) is preferably 3 or more, and more preferably 5 or more.

[0078] The concentration of ester bond groups can be determined by calculating the number of moles of ester bond groups contained in 1 g of the urethane resin. The ester bond group concentration is preferably 4 mmol / g or more, more preferably 5 mmol / g or more, from the viewpoint of improving the substrate adhesion and deinking properties of the release layer (2), and is preferably 8 mmol / g or less, more preferably 7 mmol / g or less, from the viewpoint of good blocking resistance of the primer layer.

[0079] When the coating agent is solvent-based, the acid value of the urethane resin is not particularly limited, but is, for example, 15 mg KOH / g or less. The acid value is the amount of acid in 1 g of resin calculated by titrating the acid with alkali, converted to mg of potassium hydroxide, according to JIS K0070. The acid value of the urethane resin may be 0 mg KOH / g.

[0080] When the coating agent is solvent-based, the urethane resin has a urea group concentration of, for example, 0.2 mmol / g or more, for example, 0.3 mmol / g or more, or for example, 0.6 mmol / g or more. The urea group concentration of the urethane resin is, for example, 2 mmol / g or less, for example, 1.7 mmol / g or less, or for example, 1.5 mmol / g or less. The urea group concentration is the weight of diamine contained in 1 g of urethane resin divided by the NCO equivalent mass of the constituent diamine.

[0081] Examples of organic solvents used in preparing coating agents include acetate esters such as ethyl acetate and butyl acetate, alcohols such as methanol, ethanol, n- and isopropanol, ketones such as acetone and methyl ethyl ketone, polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol, alkyl ethers of polyalkylene glycol, and N-methyl-2-pyrrolidone. Because film-forming materials, which are widely used on plastic substrates, require consideration of worker health and the environment, it is preferable to use toluene-free and methyl ethyl ketone (MEK)-free organic solvents, and ethyl acetate and isopropyl alcohol are preferred.

[0082] To improve the compatibility between the polyester polyol used in synthesizing the urethane resin and the organic solvent used in preparing the coating agent and to reduce R (HSP distance), the ethyl acetate content in the organic solvent is preferably 60% by weight or more and 100% by weight or less, and the isopropyl alcohol content is preferably 0% by weight or more and 40% by weight or less. The ethyl acetate content is more preferably 70% by weight or more, and even more preferably 80% by weight or more.

[0083] When the solvent contained in the coating agent is an aqueous solvent (hereinafter also referred to as when the coating agent is aqueous), from the viewpoint of the balance between the releasability of the release layer (2) and the aqueous dispersion stability of the urethane resin in the coating agent, it is preferable to use a urethane resin having an ester bond group concentration of 1 mmol / g or more and an acid value of 8 mg KOH / g to 45 mg KOH / g.

[0084] The ester bond concentration of the urethane resin is preferably 2 mmol / g or more, more preferably 4 mmol / g or more, and from the viewpoint of good blocking resistance of the release layer (2), it is preferably 9 mmol / g or less, more preferably 7 mmol / g or less. The acid value of the urethane resin is preferably 15 mgKOH / g or more, more preferably 20 mgKOH / g or more, and is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less.

[0085] When the coating agent is aqueous, the value obtained by dividing the mass of the raw material monomer of the polyisocyanate contained in 1 g of the urethane resin by the NCO equivalent mass of the raw material monomer of the polyisocyanate is preferably 1.0 to 6.0 mmol / g. If this value is 1.0 mmol / g or more, the substrate adhesion and deinking properties of the release layer (2) can be improved. It is more preferably 1.5 mmol / g or more, and even more preferably 1.8 mmol / g or more. If it is 6.0 mmol / g or less, the film-forming properties of the release layer (2) can be ensured, and it is more preferably 5.0 mmol / g or less, and even more preferably 4.0 mmol / g or less.

[0086] When the coating agent is aqueous, the aromatic ring concentration derived from the raw material monomer of aromatic dicarboxylic acid in the urethane resin is preferably 1 mmol / g or more. The aromatic ring concentration is determined by calculating the number of moles of aromatic rings contained in 1 g of the urethane resin. From the viewpoint of improving the substrate adhesion and deinking properties of the resulting release layer (2), the aromatic ring concentration is preferably 1.5 mmol / g or more, more preferably 2 mmol / g or more. From the viewpoint of good film-forming properties of the primer layer, the aromatic ring concentration is preferably 6 mmol / g or less, more preferably 5 mmol / g or less.

[0087] As the organic solvent used in preparing the coating agent, aqueous solvents include water, organic solvents miscible with water, and mixtures thereof. Examples of organic solvents miscible with water include alcohols such as methanol, ethanol, n- and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycol; and N-methyl-2-pyrrolidone. Water alone may be used, or a mixture of water and a water-miscible organic solvent may be used, or a water-miscible organic solvent alone may be used. From the standpoints of safety and environmental impact, water alone or a mixture of water and a water-miscible organic solvent is preferred, and water alone is particularly preferred.

[0088] When the coating agent is aqueous, the content of the urethane resin is preferably 5% to 50% by mass, more preferably 10% to 25% by mass, based on the total amount of the coating agent. The aqueous solvent is preferably contained in an amount of 50% to 95% by mass, more preferably 75% to 90% by mass, based on the total amount of the urethane resin composition.

[0089] The coating agent (solvent-based coating agent and aqueous coating agent) used to form the release layer (2) is preferably used in combination with a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amino-based crosslinking agents, aziridine-based crosslinking agents, silane coupling agent-based crosslinking agents, carbodiimide-based crosslinking agents, and oxazolidine-based crosslinking agents. It is preferable to use a polyisocyanate crosslinking agent. From the viewpoints of improving adhesion to the substrate and improving deinking properties, the crosslinking agent is preferably used in an amount of 30% by mass or less, and more preferably 20% by mass or less, based on the total amount of the urethane resin having an ester bond. Furthermore, it is preferable to mix the crosslinking agent with the coating agent immediately before applying it to the substrate.

[0090] The coating agent used to form the release layer (2) may contain various additives as needed, such as film-forming aids, curing accelerators, plasticizers, antistatic agents, waxes, light stabilizers, flow adjusters, dyes, leveling agents, rheology control agents, UV absorbers, antioxidants, photocatalytic compounds, inorganic pigments, organic pigments, extender pigments, etc. These additives are preferably used in an amount of 5% by mass or less based on the total amount of the coating agent.

[0091] The method for applying the coating agent is not particularly limited, and the coating agent can be provided by the same method as for the release layer (1). The thickness of the release layer (2) can be adjusted as appropriate, but is, for example, from 0.1 μm to 2.0 μm.

[0092] (Printing layer) The printed layer is provided on the surface of the first substrate facing the second substrate via a release layer. In other words, the printed layer is a layer disposed between the release layer and the adhesive layer, on which characters, figures, symbols, other desired designs, etc. are printed using printing ink.

[0093] The printing method and printing ink used to form the printed layer 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 films 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 water-based inks or organic solvent-based inks.

[0094] Specific examples include gravure printing ink, flexographic printing ink (in some industries, gravure printing ink and flexographic printing ink are sometimes called 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, electron-beam-curable ink for inkjet recording and printing, etc. Biomass inks made from biomass raw materials are also used as appropriate.

[0095] The printing ink may contain a resin, a colorant, and a solvent as essential components, or may be a so-called clear ink that contains a resin and a solvent but does not substantially contain a colorant. The printing layer may be provided on the entire surface of the first substrate, or may be provided only on a part of the surface.

[0096] Taking the case where the printing ink is gravure printing ink or flexographic printing ink as an example, the resin used in the printing ink is not particularly limited and includes, 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 can be used in combination. Preferably, at least one or more selected from polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, and cellulose-based resin is used.

[0097] Colorants used in printing 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.

[0098] The organic solvent used in the printing ink preferably does not contain an aromatic hydrocarbon organic solvent. More specifically, examples of the organic solvent include alcohol organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol, ketone organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, aliphatic hydrocarbon organic solvents such as n-hexane, n-heptane, and n-octane, and alicyclic hydrocarbon organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane, and these can be used alone or in combination.

[0099] In consideration of the establishment of a recycling-oriented society that should continue to develop (sustainability), it is also preferable that the liquid printing ink used in the present invention is a gravure printing ink or a flexographic printing ink that uses plant-derived raw materials.

[0100] Examples of plant-derived raw materials include cellulose resins such as cellulose acetate propionate resin and nitrocellulose; polyamide resins using dimer acids or polymerized fatty acids derived from natural oils such as soybean oil, palm oil, and rice bran oil; polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid; polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, and isosorbide; and polyisocyanates such as 1,5-pentamethylene diisocyanate and dimer diisocyanate. These polycarboxylic acids include succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid; and rosin resins.

[0101] As the biomass gravure printing ink or flexographic printing ink, commercially available products listed by the Japan Organics Recycling Association can also be used.

[0102] (Adhesive layer) The adhesive layer is a layer that bonds the first substrate and the second substrate via the release layer and the printed layer. In other words, the adhesive layer is disposed between the printed layer and the second substrate. The adhesive layer contains an acid anhydride. The adhesive layer in the laminate of the present invention is not particularly limited as long as it is such a layer, but examples include, but are not limited to, the following adhesive layers (1) to (4).

[0103] (Adhesive layer (1)) One embodiment of the adhesive layer in the laminate of the present invention is a two-component curing adhesive comprising a polyol composition containing a polyester polyol as an essential component and a polyisocyanate composition, and is a cured coating film of adhesive (1) further containing an acid anhydride.

[0104] The polyol composition contains a polyester polyol as an essential component, and may further contain polyols such as polyether polyols, vegetable oil polyols, polyurethane polyols, sugar alcohols, etc. These polyols may also be used in combination of two or more kinds.

[0105] The proportion of polyester polyol in the polyol is preferably 40% by mass or more, more preferably 60% by mass or more, and the total amount of polyol may be polyester polyol.

[0106] Examples of polyester polyols include polyester polyols that are reaction products of polyhydric alcohols and polycarboxylic acids, and lactone-based polyester polyols obtained by polycondensation reaction of aliphatic polyols and various lactones such as ε-caprolactone. It is preferable to use polyester polyols that are reaction products of polyhydric alcohols and polycarboxylic acids.

[0107] Examples of polyhydric alcohols include aliphatic diols such as ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2,4-trimethyl-1,3-pentanediol;

[0108] aliphatic polyols with three or more functional groups, such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol;

[0109] Examples include polyether polyols obtained by ring-opening polymerization of aliphatic diols or polyols with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether, and these can be used alone or in combination of two or more.

[0110] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; Aromatic dicarboxylic acids such as orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid; and anhydride or ester-forming derivatives of these aliphatic or dicarboxylic acids; Examples include polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acids, and these can be used alone or in combination of two or more.

[0111] The molecular weight of the polyester polyol is not particularly limited, but is, for example, 250 g / mol or more and 20,000 g / mol or less. The hydroxyl value of the polyester polyol is not particularly limited, but is, for example, from 5 mgKOH / g to 500 mgKOH / g.

[0112] Examples of polyether polyols include those obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, and cyclohexylene in the presence of a polymerization initiator.

[0113] Examples of the polymerization initiator include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and triethylene glycol;

[0114] tri- or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol, and triols of polypropylene glycol;

[0115] Examples include primary or secondary alkylamines such as ethylamine and diethylamine, amine compounds having multiple amino groups such as methylenediamine and ethylenediamine, and amine compounds having active hydrogen groups such as primary or secondary alkanolamines such as monoethanolamine and diethanolamine.

[0116] The molecular weight of the polyether polyol can be adjusted as appropriate, but is, for example, 100 g / mol or more and 8000 g / mol or less. The hydroxyl value of the polyether polyol can be adjusted as appropriate, but is, for example, 10 mgKOH / g or more and 1200 mgKOH / g or less.

[0117] Examples of the vegetable oil polyol include castor oil, dehydrated castor oil, hardened castor oil which is a hydrogenated castor oil, and an alkylene oxide 5 to 50 mole adduct of castor oil.

[0118] Polyurethane polyol is a reaction product of a low-molecular-weight or high-molecular-weight polyol and a polyisocyanate compound. The low-molecular-weight or high-molecular-weight polyol may be the same as the polyhydric alcohol exemplified as the raw material for polyester polyol. The polyisocyanate compound may be the same as the polyisocyanate that can be contained in the isocyanate composition described below.

[0119] Examples of sugar alcohols include pentaerythritol, sucrose, xylitol, sorbitol, isomalt, lactitol, maltitol, and mannitol.

[0120] The polyisocyanate composition contains a polyisocyanate compound having multiple isocyanate groups. The polyisocyanate compound is not particularly limited, and examples thereof include aromatic diisocyanates, araliphatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and biuret, nurate, adduct, allophanate, carbodiimide-modified, and uretdione-modified products of these diisocyanates, as well as urethane prepolymers obtained by reacting these polyisocyanates with polyols, and these can be used alone or in combination.

[0121] Examples of aromatic diisocyanates include, but are not limited to, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (also called polymeric MDI or crude MDI), 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate.

[0122] The aromatic aliphatic diisocyanate means an aliphatic isocyanate having one or more aromatic rings in the molecule, and examples thereof include, but are not limited to, m- or p-xylylene diisocyanate (also known as XDI), α,α,α',α'-tetramethylxylylene diisocyanate (also known as TMXDI), and the like.

[0123] Examples of aliphatic diisocyanates include, but are not limited to, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0124] Examples of alicyclic diisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, isophorone diisocyanate (also known as IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatomethyl)cyclohexane, but are not limited to these.

[0125] The polyol used in the synthesis of the urethane prepolymer may be the same as the polyhydric alcohols exemplified as raw materials for the polyester polyols, and may be used alone or in combination of two or more. It is preferable to use at least one polyalkylene glycol or polyester polyol having a molecular weight of 200 to 3000 g / mol.

[0126] Examples of acid anhydrides include cyclic aliphatic acid anhydrides, aromatic acid anhydrides, and unsaturated carboxylic acid anhydrides, and these may be used alone or in combination of two or more. For example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, dodecenylsuccinic anhydride, polyadipic acid anhydride, polyazelaic acid anhydride, polysebacic acid anhydride, poly(ethyloctadecanedioic) anhydride, poly(phenylhexadecanedioic) anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic acid anhydride, trialkyltetrahydrophthalic anhydride, methylsilylsilylsilylsilyl Examples of suitable dianhydrides include cyclohexene dicarboxylic anhydride, methylcyclohexene tetracarboxylic anhydride, ethylene glycol bistrimellitate dianhydride, HET anhydride, Nadic anhydride, methylnadic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexane-1,2-dicarboxylic anhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride, and 1-methyl-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic dianhydride.

[0127] Alternatively, the acid anhydride may be one obtained by modifying the above-mentioned compounds with glycol. Examples of glycols that can be used for modification include alkylene glycols such as ethylene glycol, propylene glycol, and neopentyl glycol; and polyether glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Furthermore, copolymer polyether glycols of two or more of these glycols and / or polyether glycols may also be used.

[0128] Furthermore, a polymer of an acid anhydride having an unsaturated polymerizable group, such as maleic anhydride, can also be used as the acid anhydride. The polymer may be a homopolymer or a copolymer using multiple types of acid anhydrides having an unsaturated polymerizable group. It may also be a copolymer of an acid anhydride having an unsaturated polymerizable group and another polymerizable monomer. Examples of other polymerizable monomers include, but are not limited to, α-olefins having 2 to 2 carbon atoms, such as ethylene, propylene, and 1-butene; vinyl compounds having an aromatic ring, such as styrene and p-tert-butylstyrene; conjugated polyenes, such as butadiene and isoprene; non-conjugated polyenes, such as 1,4-hexadiene, 1,7-octadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-methylene-2-norbornene, and 2,5-norbornadiene; (meth)acrylic monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; (meth)acrylic monomers having an acid group, such as (meth)acrylic acid; and acrylic esters, such as methyl (meth)acrylate and ethyl (meth)acrylate. These may be used alone or in combination of two or more.

[0129] The amount of acid anhydride blended can be adjusted as appropriate, but is, for example, 0.1% by mass to 10% by mass, more preferably 0.3% by mass to 5% by mass, of the total amount of polyol and polyisocyanate compound.

[0130] The adhesive (1) used in the present invention may be solvent-based or solventless. In this specification, a solvent-based adhesive refers to a polyol composition and a polyisocyanate composition that contain highly soluble organic solvents, such as esters (e.g., ethyl acetate, butyl acetate, cellosolve acetate), ketones (e.g., acetone, methyl ethyl ketone, isobutyl ketone, cyclohexanone), ethers (e.g., tetrahydrofuran, dioxane), aromatic hydrocarbons (e.g., toluene, xylene), halogenated hydrocarbons (e.g., methylene chloride, ethylene chloride), dimethyl sulfoxide, dimethyl sulfamide, etc.; whereas a solventless adhesive refers to a composition that is substantially free of these organic solvents. A polyol composition and a polyisocyanate composition are considered to be substantially free of organic solvents when trace amounts of organic solvent remain in the polyol composition and the polyisocyanate composition due to incomplete removal of the organic solvents used as reaction media during the production of the components of the polyol composition and the polyisocyanate composition or their raw materials. Furthermore, when the polyol composition contains a low-molecular-weight alcohol, the low-molecular-weight alcohol reacts with the polyisocyanate composition to become part of the coating film, and therefore does not need to be volatilized after coating. Therefore, this type of adhesive is also treated as a solvent-free adhesive, and the low-molecular-weight alcohol is not considered an organic solvent.

[0131] The adhesive (1) used in the present invention may contain components other than those described above, such as a urethanization catalyst, a coupling agent, a pigment, a plasticizer, a phosphoric acid derivative, etc. These components may be contained in either or both of the polyol composition and the polyisocyanate composition, or may be prepared separately from these and then mixed with the polyol composition and the polyisocyanate composition immediately before application of the adhesive (1).

[0132] The adhesive (1) is preferably used by blending it so that the ratio [NCO] / [OH] of the number of moles of isocyanate groups contained in the polyisocyanate composition (Y) to the number of moles of hydroxyl groups contained in the polyol composition (X) is 0.5 to 3.0.

[0133] In one embodiment of the present invention, the adhesive layer (1) is a cured coating film of such an adhesive (1). The adhesive (1) is applied to either the first substrate or the second substrate, directly or via an optionally provided layer, and then the substrate is laminated to the other substrate, followed by aging treatment, to form the adhesive layer (1). For example, the aging temperature is room temperature to 70°C, and the aging time is 6 to 240 hours. The amount of adhesive (1) applied is adjusted as appropriate, but for example, it is 1 g / m 2 More than 5g / m 2 The following is the result.

[0134] (Adhesive layer (2)) One embodiment of the adhesive layer in the laminate of the present invention is a multi-component, solvent-free adhesive containing an oil or fat containing an acid anhydride group and a curing agent having a reactive group capable of reacting with the acid anhydride group, and is a cured coating film of the adhesive (2) containing the acid anhydride. The fat or oil containing an acid anhydride group of the adhesive (2) can be obtained, for example, by adding an acid anhydride group-containing compound to fat or oil. Fat or oil containing an acid anhydride group is preferably obtained by introducing an acid anhydride group into fat or oil containing a double bond derived from an unsaturated fatty acid in its chemical structure.

[0135] As fats and oils containing double bonds derived from unsaturated fatty acids in their chemical structure, drying oils (iodine value >130) and / or semi-drying oils (iodine value 100-130) are preferred. Examples of vegetable oils include tung oil, linseed oil, perilla oil, safflower oil, dehydrated castor oil, safflower oil, soybean oil, rapeseed oil, sunflower oil, sesame oil, rice oil, cottonseed oil, corn oil, tall oil, poppy oil, walnut oil, and pine seed oil. Examples of animal oils include fish oils (sardine oil, saury oil, herring oil, etc.). In the present invention, recycled vegetable oils recovered and recycled after being used for cooking, such as tempura oil, can also be used. Among these fats and oils, tung oil, soybean oil, and linseed oil are preferred due to their ease of availability. Furthermore, grades of oils and oils known as refined oils or salad oils, which are refined so as not to crystallize even at low temperatures for long periods of time, are preferred.

[0136] As the acid anhydride group-containing compound used for introducing the acid anhydride group, a compound having a double bond in the molecule can be used, and examples thereof include maleic anhydride, citraconic anhydride, and tetrahydrophthalic anhydride. Among these, maleic anhydride is preferred for use in view of ease of introduction and the reactivity of the acid anhydride group.

[0137] The amount of acid anhydride groups introduced into fats and oils can be adjusted as appropriate. Taking the case of introducing maleic anhydride as an example, the amount of maleic anhydride introduced is, for example, 19 to 34 g (0.19 to 0.35 mol) of maleic anhydride per 100 g of fats and oils, and more preferably 22 to 29 g (0.22 to 0.30 mol).

[0138] Various acids may be used in combination with fats and oils containing an acid anhydride group, such as hydroxycarboxylic acids such as citric acid, isocitric acid, malic acid, and tartaric acid, phosphoric acid, monoalkyl phosphate esters, dialkyl phosphate esters, acetic acid, alkyl (C2-18) monocarboxylic acids, and dimer acids. These may be added when the acid anhydride is added to the fats and oils, or may be added after the addition reaction is complete.

[0139] Examples of curing agents having a reactive group capable of reacting with an acid anhydride group include nitrogen-containing compounds such as tertiary amine-containing polyols, amino alcohols, amide polyols, and polyamines, as well as compounds having a hydroxyl group. Tertiary amine-containing polyols are particularly preferred because they allow for easy adjustment of the balance between the reactivity with oils and fats containing an acid anhydride group and the physical properties of the film formed.

[0140] The tertiary amine-containing polyol particularly preferably has 2 to 6 hydroxyl groups. It is sufficient for the tertiary amine-containing polyol to have one or more tertiary amino groups, but it is preferable for the tertiary amine-containing polyol to have 1 to 2 tertiary amino groups. Specific examples include polypropylene glycol ethylenediamine ether, tri(1,2-polypropylene glycol)amine, N-ethyldiethanolamine, N-methyl-N-hydroxyethyl-N-hydroxyethoxyethylamine, pentakishydroxypropyldiethylenetriamine, and tetrakishydroxypropylethylenediamine.

[0141] The tertiary amine-containing polyol may be a commercially available product, such as TE-360 (a tertiary amine-containing trifunctional polyol manufactured by Guodo Chemical Co., Ltd. (China)), TD-401 (a tertiary amine-containing tetrafunctional polyol manufactured by Guodo Chemical Co., Ltd. (China), EDP-300, or EDP-450 (all tertiary amine-containing tetrafunctional polyols manufactured by Adeka Corporation).

[0142] Examples of amino alcohols having both a primary or secondary amino group and a hydroxyl group in one molecule include monomethanolamine, N-methylmethanolamine, N-ethylmethanolamine, dimethanolamine, monoethanolamine, N-methylethanolamine, N-ethylethanolamine, and diethanolamine.

[0143] Examples of amide polyols include polyesteramide polyols, and polyesteramide polyols obtained by using, as a raw material, an aliphatic diamine having an amino group, such as ethylenediamine, propylenediamine, or hexamethylenediamine, in the esterification reaction of the polyester polyol.

[0144] The polyamine is not particularly limited, and known polyamines having primary and / or secondary amino groups can be used. The polyamine may also contain a tertiary amine.

[0145] More specifically, aliphatic diamines having 2 to 18 carbon atoms, such as alkylenediamines, such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, and hexamethylenediamine, and polyalkylenediamines, such as diethylenetriamine, iminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine;

[0146] alkyl (having 1 to 4 carbon atoms) or hydroxyalkyl (having 2 to 4 carbon atoms) substituted aliphatic diamines such as dialkylaminopropylamines having 1 to 3 carbon atoms, trimethylhexamethylenediamine, aminoethylethanolamine, 2,5-dimethyl-2,5-hexamethylenediamine and methyliminobispropylamine;

[0147] Alicyclic or heterocyclic ring-containing aliphatic diamines typified by alicyclic diamines having 4 to 15 carbon atoms, such as 1,3-diaminocyclohexane, isophoronediamine, menthenediamine, and 4,4'-methylenedicyclohexanediamine (hydrogenated methylenedianiline), and heterocyclic diamines having 4 to 15 carbon atoms, such as piperazine, N-aminoethylpiperazine, 1,4-diaminoethylpiperazine, and 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane;

[0148] aromatic ring-containing aliphatic amines having 8 to 15 carbon atoms, such as xylylenediamine and tetrachloro-p-xylylenediamine;

[0149] unsubstituted aromatic diamines having 6 to 20 carbon atoms, such as 1,2-, 1,3-, or 1,4-phenylenediamine, 2,4'- and 4,4'-diphenylmethanediamine, crude diphenylmethanediamine (polyphenylpolymethylenepolyamine), diaminodiphenylsulfone, benzidine, thiodianiline, 2,6-diaminopyridine, m-aminobenzylamine, triphenylmethane-4,4',4"-triamine, and naphthylenediamine;

[0150] aromatic diamines having a nucleus-substituted alkyl group having 1 to 4 carbon atoms, such as 2,4- or 2,6-tolylenediamine, crude tolylenediamine, diethyltolylenediamine, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-bis(o-toluidine), dianisidine, diaminoditolyl sulfone, 1,3-dimethyl-2,4-diaminobenzene, 2,3-dimethyl-1,4-diaminonaphthalene, and 4,4'-diamino-3,3'-dimethyldiphenylmethane, and mixtures of these isomers in various ratios;

[0151] aromatic diamines having a nucleus-substituted electron-withdrawing group (halogen atoms such as fluorine, chlorine, bromine, and iodine; alkoxy groups such as methoxy and ethoxy; nitro group, etc.), such as methylenebis-o-chloroaniline, 4-chloro-o-phenylenediamine, 2-chloro-1,4-phenylenediamine, 3-amino-4-chloroaniline, 4-bromo-1,3-phenylenediamine, 2,5-dichloro-1,4-phenylenediamine, 5-nitro-1,3-phenylenediamine, and 3-dimethoxy-4-aminoaniline;

[0152] Aromatic diamines having a secondary amino group, such as 4,4'-di(methylamino)diphenylmethane and 1-methyl-2-methylamino-4-aminobenzene (the above aromatic diamines in which part or all of -NH2 has been substituted with -NH-R' (R' is an alkyl group; for example, a lower alkyl group such as a methyl group or an ethyl group));

[0153] low-molecular-weight polyamide polyamines obtained by condensing dicarboxylic acids such as dimer acids with polyamines such as the alkylenediamines and polyalkylene polyamines described above under conditions in which the amino groups are in excess relative to the acid groups (2 moles or more of amino groups per mole of acid groups);

[0154] Examples include polyether polyamines, which are hydrogenated cyanoethylated polyether polyols such as polyalkylene glycols.

[0155] Among these, polyamidoamines and polyether polyamines are preferably used because they can form coatings with excellent strength.

[0156] Commercially available polyamines can also be used, such as Jeffamine T-403, Jeffamine D-230, and Jeffamine D-400 (all polyether polyamines manufactured by Huntsman (USA)).

[0157] In the case of polyether polyamines, those which are preferably bifunctional or trifunctional and have a molecular weight of 200 to 5,000, more preferably 200 to 1,500, are preferably used.

[0158] As the compound containing a hydroxyl group, for example, a compound containing an average of two or more hydroxyl groups in the molecule can be suitably used, and examples thereof include polymer polyols selected from polyester polyols, polyether polyols, polyurethane polyols, polyether ester polyols, polyester (polyurethane) polyols, polyether (polyurethane) polyols, acrylic polyols, polycarbonate polyols, polyhydroxyl alkanes, castor oil, and mixtures thereof.

[0159] The polyester polyols that can be used are the same as those exemplified as components of the polyol composition of the adhesive (1), and those having a number average molecular weight of 400 to 2000 and a hydroxyl value of 60 to 300 are preferably used.

[0160] The polyether polyols and polyurethane polyols that can be used are the same as those exemplified as components of the polyol composition of the adhesive (1). Examples of polyether ester polyols include polyether ester polyols obtained by reacting the above-mentioned polyether polyols with dibasic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, and dimer acid, or dialkyl esters thereof, or mixtures thereof.

[0161] Examples of polycarbonate polyols include those obtained by reacting one or more glycols selected from ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, and hydrogenated bisphenol A with dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, or the like.

[0162] Acrylic polyols can be obtained by copolymerizing hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, or the like, which contain one or more hydroxyl groups in one molecule, or their corresponding methacrylic acid derivatives, with, for example, acrylic acid, methacrylic acid, or an ester thereof. Examples of polyhydroxyalkanes include liquid rubbers obtained by copolymerizing butadiene or butadiene with acrylamide or the like.

[0163] Examples of polyhydroxyalkanes include glycols (diols) such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol, and trihydric or tetrahydric alcohols such as glycerin, trimethylolpropane, and pentaerythritol.

[0164] As the compound containing a hydroxyl group, it is preferable to use at least one polyester polyol, since the reactivity of the hydroxyl group is high and the curability can be improved.

[0165] The curing agent preferably contains at least one nitrogen-containing compound. Only one nitrogen-containing compound may be used, or multiple nitrogen-containing compounds may be used in combination. The nitrogen-containing compound not only contributes to the formation of a cured adhesive as a curing agent, but also, when the curing agent contains a hydroxyl group-containing oil-containing compound, the nitrogen contained in the structure acts as a catalyst to promote the reaction between the acid anhydride group and the hydroxyl group, thereby improving the curing rate.

[0166] As the acid anhydride, the same ones as those exemplified as components of the adhesive (1) can be used. The amount of acid anhydride blended can be adjusted as appropriate, but as an example, it is 0.1% by mass or more and 10% by mass or less of the total amount of the oil or fat containing an acid anhydride group and the curing agent, and more preferably 0.3% by mass or more and 5% by mass or less.

[0167] The fats and oils containing acid anhydride groups and the curing agent are preferably used such that the molar ratio of the acid anhydride groups in the fats and oils to the functional groups in the curing agent that can react with the acid anhydride groups (acid anhydride groups / functional groups that can react with acid anhydride groups) is in the range of 0.5 to 1.5, more preferably 0.8 to 1.25.

[0168] When the curing agent contains a nitrogen-containing compound, the amount of curing agent used is preferably such that the molar ratio of nitrogen in the nitrogen-containing compound to the acid anhydride group in the oil or fat (nitrogen / acid anhydride group) is in the range of 0.5 to 0.8, more preferably 0.5 to 0.65.

[0169] Preferred combinations of fats and oils containing an acid anhydride group and curing agents include a combination of fats and oils containing maleic anhydride-modified tung oil with a curing agent containing a polyester polyol and a tertiary amine-containing polyol, a combination of fats and oils containing maleic anhydride-modified soybean oil with a curing agent containing a polyester polyol and a polyether polyamine, and a combination of fats and oils containing maleic anhydride-modified soybean oil and tung oil with a curing agent containing a polyester polyol, a polyether polyamine, and a tertiary amine-containing polyol.

[0170] If necessary, a polycarbodiimide compound may be used as the adhesive (2). The polycarbodiimide compound reacts with the carboxylic acid produced by the reaction between the oil or fat containing an acid anhydride group and the curing agent to form a denser cured adhesive, thereby improving adhesive strength.

[0171] The polycarbodiimide compound is not particularly limited and any known polycarbodiimide compound can be used. The molecular weight of the polycarbodiimide compound is preferably in the range of 1,000 to 5,000, more preferably 2,000 to 4,000, calculated as the number average molecular weight.

[0172] The carbodiimide compound can be obtained as a commercially available product, for example, Carbodilite V02B (solid content concentration 100%, carbodiimide equivalent weight 600), Carbodilite V05 (solid content concentration 100%, carbodiimide equivalent weight 262), Carbodilite V04PF (solid content concentration 100%, carbodiimide equivalent weight 336), Carbodilite V05S (solid content concentration 90% by mass, carbodiimide group equivalent weight 291 (solid content equivalent weight 262) ), Carbodilite V07 (solid content concentration 50% by mass, carbodiimide group equivalent weight 404 (solid content equivalent weight 202)), Carbodilite V09GB (solid content concentration 70% by mass, carbodiimide group equivalent weight 298 (solid content equivalent weight 209) (all manufactured by Nisshinbo Chemical Inc.), and the like are exemplified, with V02B and V05 being preferred. The carbodiimide-containing component may be contained alone or in combination of two or more kinds.

[0173] When a polycarbodiimide compound is used, it is preferable to keep the amount used as small as possible, since the polycarbodiimide compound has a high viscosity and may affect the coating suitability.

[0174] The adhesive (2) may contain components other than the above-mentioned acid anhydride group-containing oil and curing agent. Such components include, but are not limited to, catalysts, coupling agents, hydroxycarboxylic acids, oxygen scavengers, phosphoric acids, pigments, tackifiers, stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, crystal nucleating agents, antifoaming agents, leveling agents, etc. These components may be contained in only one of the first composition and the second composition described below, or in both.

[0175] In one embodiment of the present invention, the adhesive layer is a cured coating of such adhesive (2). The adhesive is applied to either the first substrate or the second substrate, either directly or via a first resin layer or any other layer that is optionally provided, and then the substrate is laminated to the other substrate, followed by aging treatment, to form the adhesive layer (2). For example, the aging temperature is room temperature to 70°C, and the aging time is 6 to 240 hours. The amount of adhesive (2) applied is adjusted as appropriate, but for example, it is 1 g / m 2 More than 5g / m 2 The following is the result.

[0176] (Adhesive layer (3)) One embodiment of the adhesive layer in the laminate of the present invention is a cured coating film of an adhesive (3) whose main component is an olefin resin modified with an acid and / or a hydroxyl group and further contains an acid anhydride.

[0177] Examples of the olefin-based resin modified with an acid and / or a hydroxyl group used in the adhesive (3) include a copolymer of an olefin-based monomer and a polymerizable monomer having an acid group (or an acid anhydride group) and / or a hydroxyl group, and a resin obtained by graft-modifying an olefin resin with a polymerizable monomer having an acid group (or an acid anhydride group) and / or a hydroxyl group.

[0178] Examples of olefin resins having an acid group and / or an acid anhydride group include copolymers of olefin-based monomers and ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic acid anhydrides, and resins in which polyolefins are graft-modified with ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic acid anhydrides.

[0179] Examples of the olefin-based monomer include olefins having 2 to 8 carbon atoms, such as ethylene, propylene, isobutylene, 1-butene, 4-methyl-1-pentene, hexene, vinylcyclohexane, etc. Among these, olefins having 2 to 8 carbon atoms are preferred because they provide particularly good adhesive strength, and it is preferable to use ethylene, propylene, and 1-butene.

[0180] Examples of the ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic acid anhydride used in copolymerization with an olefin-based monomer include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, 4-methylcyclohex-4-ene-1,2-dicarboxylic anhydride, bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride, 1,2,3,4,5,8,9,10-octahydronaphthalene Examples of suitable maleic anhydrides include methyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, 2-octa-1,3-diketospiro[4.4]non-7-ene, bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, maleopimaric acid, tetrahydrophthalic anhydride, methyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, methyl-norbornene-5-ene-2,3-dicarboxylic anhydride, and norborn-5-ene-2,3-dicarboxylic anhydride. Among these, maleic anhydride is particularly preferred due to its excellent reactivity with olefinic monomers, the reactivity of the resulting anhydride after copolymerization, and the low molecular weight of the compound itself, resulting in a high functional group concentration when copolymerized. These may be used alone or in combination of two or more.

[0181] In addition to the olefinic monomer, ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic acid anhydride, other compounds having an ethylenically unsaturated group, such as styrene, butadiene, isoprene, etc. may be used in combination.

[0182] Examples of polyolefins used in synthesizing acid-modified olefin resins by graft modification include homopolymers and copolymers of olefins having 2 to 8 carbon atoms, and copolymers of olefins having 2 to 8 carbon atoms with other monomers. Specific examples include polyethylenes such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene resins; polypropylene; polyisobutylene; poly(1-butene); poly(4-methyl-1-pentene); polyvinylcyclohexane; α-olefin copolymers such as ethylene-propylene block copolymers, ethylene-propylene random copolymers, ethylene-1-butene copolymers, ethylene-4-methyl-1-pentene copolymers, and ethylene-hexene copolymers; ethylene-vinyl acetate copolymers; ethylene-methyl methacrylate copolymers; ethylene-vinyl acetate-methyl methacrylate copolymers; propylene-1-butene copolymers; and ethylene-propylene-1-butene copolymers. Among these, homopolymers of olefins having 2 to 8 carbon atoms and copolymers of two or more olefins having 2 to 8 carbon atoms are preferred because they provide particularly good adhesive strength, and ethylene-propylene copolymers, ethylene-1-butene copolymers, propylene-1-butene copolymers, and ethylene-propylene-1-butene copolymers are particularly preferred.

[0183] The ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic acid anhydride used for graft-modification with polyolefin can be the same as those exemplified above. Maleic anhydride is preferred because it has high reactivity of functional groups after graft-modification and also increases the functional group concentration of the graft-modified polyolefin. These can be used alone or in combination of two or more.

[0184] The olefin resin having an acid group and / or an acid anhydride group preferably has an acid value of 1 to 200 mgKOH / g.

[0185] Examples of olefin resins having hydroxyl groups include copolymers of polyolefins with hydroxyl group-containing (meth)acrylic esters or hydroxyl group-containing vinyl ethers, and resins obtained by graft-modifying polyolefins with hydroxyl group-containing (meth)acrylic esters or hydroxyl group-containing vinyl ethers. The polyolefins that can be used are the same as those used in the synthesis of olefin resins having acid groups and / or acid anhydride groups.

[0186] Examples of hydroxyl group-containing (meth)acrylic acid esters include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycerol (meth)acrylate, lactone-modified hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate. Examples of the hydroxyl group-containing vinyl ether include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether.

[0187] The olefin resin having a hydroxyl group preferably has a hydroxyl value of 1 to 200 mgKOH / g.

[0188] The weight average molecular weight of the olefin resin modified with an acid and / or a hydroxyl group is preferably 40,000 or more and 250,000 or less.

[0189] The melting point of the olefin resin modified with an acid and / or a hydroxyl group is preferably 40° C. or higher, more preferably 50° C. or higher, and even more preferably 60° C. or higher. The melting point of the olefin resin (A) is preferably 120° C. or lower, more preferably 90° C. or lower, and even more preferably 85° C. or lower.

[0190] As the acid anhydride, the same ones as those exemplified as components of the adhesive (1) can be used. The amount of acid anhydride blended can be adjusted as appropriate, but as an example, it is 0.1% by mass or more and 10% by mass or less of the total amount of the olefin resin modified with an acid and / or a hydroxyl group and the curing agent described below, and more preferably 0.3% by mass or more and 5% by mass or less.

[0191] The adhesive (3) is preferably used in combination with a curing agent. There are no particular limitations on the curing agent, and any compound that can crosslink acid groups, acid anhydride groups, and / or hydroxyl groups can be used. Specifically, at least one compound selected from the group consisting of isocyanate compounds, epoxy compounds, carbodiimide compounds, silane coupling agents, and metal compounds is preferred.

[0192] The isocyanate compound may be the same as those exemplified for the adhesive (1). The isocyanate compounds may be used alone or in combination of two or more.

[0193] The epoxy compound is not particularly limited as long as it is a compound having an epoxy group in the molecule, and examples thereof include polyglycidyl ether epoxy resins of aliphatic polyols such as ethylene glycol, propylene glycol, hexanediol, neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, glycerin, diglycerin, sorbitol, spiroglycol, and hydrogenated bisphenol A; Bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, and bisphenol AD-type epoxy resin; Aromatic epoxy resins such as novolac-type epoxy resins, which are glycidyl ethers of phenol novolac resins and cresol novolac resins; Polyglycidyl ethers of polyols, which are ethylene oxide or propylene oxide adducts of aromatic polyhydroxy compounds such as bisphenol A, bisphenol F, bisphenol S, and bisphenol AD; Polyglycidyl ether type epoxy resins of polyether polyols such as polyethylene glycol, polypropylene glycol, or polytetramethylene glycol; cycloaliphatic type polyepoxy resins such as bis(3,4-epoxycyclohexylmethyl) adipate and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate; Polyglycidyl ester type epoxy resins of polycarboxylic acids such as propanetricarboxylic acid, butanetetracarboxylic acid, adipic acid, phthalic acid, terephthalic acid, and trimellitic acid; Bisepoxy resins of hydrocarbon dienes such as butadiene, hexadiene, octadiene, dodecadiene, cyclooctadiene, α-pinene or vinylcyclohexene; Epoxy resins of diene polymers such as polybutadiene or polyisoprene; Glycidylamine-type epoxy resins such as tetraglycidyldiaminodiphenylmethane, triglycidyl paraaminophenol, tetraglycidyl bisaminomethylcyclohexane, diglycidylaniline, and tetraglycidyl metaxylylenediamine; Examples include epoxy resins containing heterocycles such as triazine and hydantoin. These epoxy resins may be used alone or in combination of two or more.

[0194] Examples of the carbodiimide compound include N,N'-di-o-toluylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N,N'-bis(2,6-diisopropylphenyl)carbodiimide, N,N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N,N'-di-2,2-tert.-butylphenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-di-cyclohexylcarbodiimide, and N,N'-di-p-toluylcarbodiimide.

[0195] Examples of silane coupling agents include aminosilanes such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; epoxysilanes such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane; vinylsilanes such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane; hexamethyldisilazane, γ-mercaptopropyltrimethoxysilane, and the like.

[0196] The metal compound can be used without any particular limitation as long as it forms an ionic crosslink with the olefin resin modified with an acid and / or a hydroxyl group. Specifically, it is a compound containing a metal ion, and examples thereof include metal oxides, hydroxides, carbonates, bicarbonates, acetates, formates, methoxides, and ethoxides. Examples of metal ions include Li + , Na + , K. + , Ag + , Cu + Monovalent ions such as Cu2+ , Ba 2+ , Zn 2+ , Fe 2+ These metal ions may be mixed together as needed.

[0197] Other usable compounds include aziridine group-containing compounds, oxazolines, amino resins, etc. Examples of aziridine group-containing compounds include N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, N,N'-toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, trimethylolpropane-tri-β(2-methylaziridine)propionate, bisisophthaloyl-1-2-methylaziridine, tri-1-aziridinylphosphine oxide, and tris-1-2-methylaziridinephosphine oxide.

[0198] Examples of oxazolines include monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, and 2,4-diphenyl-2-oxazoline, as well as 2,2'-(1,3-phenylene)-bis(2-oxazoline), 2,2'-(1,2-ethylene)-bis(2-oxazoline), 2,2'-(1,4butylene)-bis(2-oxazoline), and 2,2'-(1,4-phenylene)-bis(2-oxazoline).

[0199] Examples of the amino resin include melamine resin, benzoguanamine resin, and urea resin.

[0200] The amount of curing agent in the adhesive (3) is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the acid- and / or hydroxyl-modified olefin-based resin. The amount of curing agent is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 25 parts by mass or less, per 100 parts by mass of the acid- and / or hydroxyl-modified olefin-based resin.

[0201] In addition to the above components, the adhesive (3) can be blended with an organic solvent to ensure fluidity and develop appropriate coatability. Such organic solvents are not particularly limited as long as they can be evaporated and removed by heating in the drying step during adhesive application, and examples include aromatic organic solvents such as toluene and xylene; aliphatic organic solvents such as n-hexane and n-heptane; alicyclic organic solvents such as cyclohexane and methylcyclohexane; halogenated organic solvents such as trichloroethylene, dichloroethylene, chlorobenzene and chloroform; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ethanol, methanol, n-propanol, 2-propanol (isopropyl alcohol), and the like. Examples of suitable solvents include alcohol-based solvents such as diisopropyl ether, butanol, and hexanol; ether-based solvents such as diisopropyl ether, butyl cellosolve, tetrahydrofuran, dioxane, and butyl carbitol; glycol ether-based solvents such as diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, and propylene glycol monomethyl ether; and glycol ester-based solvents such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate. These may be used alone or in combination of two or more.

[0202] It is preferable to use a mixed solvent of an alicyclic organic solvent and an ester solvent. In particular, when an olefin resin having an acid group, an acid anhydride group, and / or a hydroxyl group is used, it is preferable to use a mixed solvent of methylcyclohexane and ethyl acetate because of its excellent solubility.

[0203] The amount of organic solvent used is preferably such that the proportion of the olefin resin relative to the total mass of the olefin resin having an acid anhydride group and / or a hydroxyl group and the organic solvent is 10 to 30 mass %, which allows for an adhesive with excellent coatability and wettability to substrates.

[0204] The adhesive (3) may contain various additives, such as tackifiers, plasticizers, thermoplastic elastomers, reactive elastomers, phosphate compounds, silane coupling agents, adhesion promoters, catalysts, leveling agents, inorganic fine particles such as colloidal silica and alumina sol, polymethyl methacrylate organic fine particles, defoamers, anti-sagging agents, wetting and dispersing agents, viscosity modifiers, UV absorbers, metal deactivators, peroxide decomposers, flame retardants, reinforcing agents, lubricants, rust inhibitors, fluorescent brighteners, inorganic heat absorbers, flame retardants, antistatic agents, dehydrating agents, etc. The content of these additives may be adjusted as appropriate within a range that does not impair the functionality of the adhesive.

[0205] In one embodiment of the present invention, the adhesive layer is a cured coating of such adhesive (3). The adhesive is applied to either the first substrate or the second substrate, either directly or via a first resin layer or any other layer that is optionally provided, and then the substrate is laminated to the other substrate, followed by aging treatment, to form the adhesive layer (3). As an example, the aging temperature is room temperature to 70°C, and the aging time is 6 to 240 hours. The amount of adhesive (3) applied is adjusted as appropriate, but as an example, it is 1 g / m 2 More than 5g / m 2 The following is the result.

[0206] (Adhesive layer (4)) The adhesive layer may be formed using an anchor coating agent (4) used in a typical extrusion lamination method. Examples of such anchor coating agents (4) include polyurethane-based, polyolefin-based, polyethyleneimine-based, and epoxy resin-based anchor coating agents containing acid anhydrides. After the anchor coating agent (4) is applied to the first substrate via a release layer and a printing layer, the resin material of the second substrate is extruded. Examples of the resin material of the second substrate extruded at this time include polyethylene resin.

[0207] As the acid anhydride, the same ones as those exemplified as components of the adhesive (1) can be used. The amount of acid anhydride added can be adjusted as appropriate, but is, for example, from 0.1 to 10% by mass, more preferably from 0.3 to 5% by mass, of the total solid content of the anchor coating agent (4).

[0208] The anchor coating agent (4) can be applied by a coating method such as roll coating, gravure roll coating, or kiss coating, or by a printing method. The thickness of the adhesive layer (4) formed by the anchor coating agent (4) is, for example, from 0.05 μm to 3.0 μm, preferably from 0.1 μm to 2.0 μm, and more preferably from 0.2 μm to 1.0 μm.

[0209] (Third substrate) The laminate of the present invention may include a third substrate in addition to the first substrate and the second substrate. The third substrate may be the same as the first substrate. In one embodiment of the present invention, the second substrate is a film (sealant film) having heat-sealability that can be melted by heat and fused to each other, and the first substrate and the third substrate are substrates that are not expected to function as sealant films. In another embodiment of the present invention, all of the first substrate, the second substrate, and the third substrate are substrates that are not expected to function as sealant films.

[0210] When the laminate of the present invention includes a third substrate, the third substrate is, for example, disposed between the first substrate and the second substrate, a release layer is provided on the third substrate side of the first substrate, a printed layer is provided on the release layer, the above-mentioned adhesive layer is provided on the printed layer, and the first substrate and the third substrate are bonded together via the release layer, the printed layer, and the adhesive layer. This ensures that the first substrate and the third substrate are successfully separated in the peeling step of the recycling method described below, and the printed layer and adhesive layer peeled from the first substrate and the third substrate are not too fine, so that when removing them from the release agent, pieces of the printed layer and the adhesive layer can be recovered even with a filter having a relatively large opening diameter, and the release agent can be efficiently filtered.

[0211] The third substrate and the second substrate are bonded together by a laminating adhesive, either directly or via another layer provided as needed. The laminating adhesive may be one whose adhesive strength is likely to decrease when immersed in a release agent described below for a certain period of time, causing the second substrate and the third substrate to separate, or it may not be one that is. When a laminating adhesive whose adhesive strength is not likely to decrease even when immersed in a release agent is used, it is preferable that the second substrate or the third substrate have a layer similar to the above-mentioned release layer or a metal vapor deposition layer.

[0212] (barrier coat layer) The laminate of the present invention may include layers other than those described above. One example of such a layer is a barrier coating layer. The barrier coating layer is a layer that prevents the permeation of oxygen and water vapor, and can be provided at any position of the laminate of the present invention by applying and drying a barrier coating agent.

[0213] An example of the barrier coating agent is a barrier coating agent (1) containing a vinyl alcohol polymer and an aqueous solvent.

[0214] Specific examples of vinyl alcohol polymers include polyvinyl alcohol, ethylene vinyl alcohol, and polyvinyl butyral. The vinyl alcohol polymer may have a reactive functional group other than a hydroxyl group, such as an acetoacetyl group, a carboxyl group, an anionic carboxyl group, a sulfonic acid group, or an anionic sulfonic acid group. These may be used alone or in combination of two or more.

[0215] The aqueous solvent may be water or the same water-soluble organic solvents as those exemplified as those usable for preparing the coating agent used to form the release layer. The aqueous solvents may be used alone or in combination of two or more.

[0216] The barrier coating agent (1) may further contain additives such as a layered inorganic compound, a crosslinking agent capable of reacting with a functional group possessed by the vinyl alcohol polymer, an adhesion improver, 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.

[0217] Commercially available barrier coating agents (1) can also be used, and examples thereof include EXEVIA (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., the SunBar (registered trademark) series manufactured by Sun Chemical Co., Ltd., the Takelac WPB (registered trademark) series manufactured by Mitsui Chemicals, Inc., and LG-OX manufactured by Tokyo Ink Co., Ltd.

[0218] The barrier coating agent is a water-soluble polymer with hydroxyl groups and Si(OR 1 )4, or R 2 Si(OR 3 )3(However, OR 1 and OR 3 represents a hydrolyzable group, and R 2 represents an organic functional group), or one or more hydrolyzates of the silicon compounds.

[0219] Examples of water-soluble polymers having a hydroxyl group include vinyl alcohol polymers, polyvinylpyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate.

[0220] Examples of silicon compounds or hydrolysates of the silicon compounds include tetraalkoxysilanes such as tetraethylsilicate (Si(OC2H5)4) (hereinafter sometimes referred to as TEOS) and tetramethylsilicate; trialkoxysilanes such as trimethoxymethylsilane, triethoxymethylsilane, and trimethoxyvinylsilane; dialkoxysilanes such as dimethoxydimethylsilane and diethoxydimethylsilane; monoalkoxysilanes such as methoxytrimethylsilane and ethoxytrimethylsilane, and hydrolysates or partial hydrolysates thereof.

[0221] TEOS is preferred because it is relatively stable in aqueous solvents after hydrolysis. 2 Si(OR 3 )3 contains R 2 is preferably a vinyl group, an epoxy group, an acryloyl group, a methacryloxy group, a ureido group, or an isocyanate group.

[0222] The barrier coating agent (2) may contain components other than those mentioned above, such as other water-soluble polymers (e.g., sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.), fragrances, rust inhibitors, colorants, bulking agents, antifoaming agents, ultraviolet absorbers, fluorescent brighteners, liquid paraffins, bitter components (e.g., denatonium benzoate, etc.), etc. The barrier coating agent (2) can be made of the same aqueous solvent as the gas barrier coating agent (1).

[0223] An example of a barrier coating agent is a barrier coating agent (3) containing a polyester polyol, which is a reaction product of an acid component that essentially contains an ortho-oriented polycarboxylic acid or a meta-oriented polycarboxylic acid and a polyol component, and an isocyanate compound.

[0224] Examples of ortho-oriented polycarboxylic acids include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracene carboxylic acid or its anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimide group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, or a naphthyl group.

[0225] Examples of meta-oriented polycarboxylic acids include isophthalic acid, 1,3-naphthalenedicarboxylic acid, etc. These compounds may have the same substituents as those exemplified in the description of ortho-oriented polycarboxylic acids on any carbon atom of the aromatic ring.

[0226] The polycarboxylic acid used in the synthesis of the polyester polyol may contain a polycarboxylic acid other than an ortho-oriented polycarboxylic acid or a meta-oriented polycarboxylic acid. Examples of such a polycarboxylic acid include aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; unsaturated bond-containing polycarboxylic acids such as maleic anhydride, maleic acid, and fumaric acid; alicyclic polycarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; terephthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 1,5-anthracenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, and 1,4-anthracenedicarboxylic acid. Examples of aromatic polycarboxylic acids include helical dicarboxylic acids, 2,6-anthracene dicarboxylic acid, 2,7-anthracene dicarboxylic acid, 1,8-anthracene dicarboxylic acid, 9,10-anthracene dicarboxylic acid, biphenyl dicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, and the anhydrides or ester-forming derivatives of these dicarboxylic acids, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and the ester-forming derivatives of these dihydroxycarboxylic acids, and the like, and one or more of these can be used in combination. Among these, succinic acid, 1,3-cyclopentane dicarboxylic acid, and the anhydrides thereof are preferred.

[0227] When the polycarboxylic acid contains a polycarboxylic acid other than an ortho-oriented polycarboxylic acid or a meta-oriented polycarboxylic acid, the proportion of the ortho-oriented polycarboxylic acid or the meta-oriented polycarboxylic acid in the total amount of polycarboxylic acids is preferably 40 to 100 mass%.

[0228] The polyhydric alcohol used in the synthesis of polyester polyol preferably contains a dihydric alcohol such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, or cyclohexanedimethanol, or a trihydric alcohol such as glycerol, trimethylolethane, or trimethylolpropane. Among these, it is more preferable to contain ethylene glycol or glycerol. It is particularly preferable to contain glycerol. The polyhydric alcohol preferably contains 10 to 100% by mass of glycerol.

[0229] Polyhydric alcohols other than those mentioned above may be used in combination. Examples of the polyhydric alcohol include aliphatic diols such as 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol; trihydric or higher polyhydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl)isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythritol; hydroquinone, resorcinol, catechol, naphthalenediol, biphenol, bisphenol A, bisphenol F, and tetramethylbiphenol; ethylene oxide-extended products of these; and aromatic polyhydric phenols such as hydrogenated alicyclic alcohols.

[0230] When the polyester polyol has three or more hydroxyl groups, some of the hydroxyl groups may be modified with a polycarboxylic acid or its acid anhydride. The proportion of hydroxyl groups modified with the polycarboxylic acid is preferably one-third or less of the hydroxyl groups of the polyester polyol. Examples of polycarboxylic acids used for modification include, but are not limited to, succinic anhydride, maleic acid, fumaric acid, 1,2-cyclohexanedicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, trimellitic anhydride, oleic acid, and sorbic acid.

[0231] The polyester polyol may be a polyester polyurethane polyol having a number average molecular weight of 1000 to 15000, which has been subjected to urethane elongation through a reaction with a diisocyanate compound. The urethane-elongated polyester polyol contains components with molecular weights above a certain level and urethane bonds, and therefore has excellent gas barrier properties and initial cohesive strength.

[0232] The isocyanate compound used in the barrier coating agent (3) may be the same as the polyisocyanate compound used in the adhesive (1), and is preferably one having an aromatic ring or an aliphatic ring. Examples of isocyanate compounds having an aromatic ring or an aliphatic ring include toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, trimers of these isocyanate compounds, and adducts obtained by reacting an excess amount of these isocyanate compounds with low-molecular-weight active hydrogen compounds such as ethylene glycol, propylene glycol, meta-xylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, and meta-xylylenediamine, and alkylene oxide adducts thereof, various polyester resins, polyether polyols, and high-molecular-weight active hydrogen compounds such as polyamides. The isocyanate compounds may be used alone or in combination.

[0233] It is also preferable to use a compound having an active hydrogen group in combination with the barrier coating agent (3). Examples of the active hydrogen group in the compound having active hydrogen include a hydroxyl group, an amino group, an imino group, a carboxylic acid, a urea group, and an SH group. Among these, a hydroxyl group, an amino group, and an SH group are preferred.

[0234] When the solubility parameter of the compound having active hydrogen is 29.5 or less, the compatibility between the polyester polyol and the isocyanate compound is improved, the compound having active hydrogen is uniformly present in the barrier coat layer, and improved gas barrier properties can be expected.In this specification, the solubility parameter refers to the δT value listed in the Hansen Solubility Parameter Calculation Software (HSPiP) or the δT value calculated using the SMILES notation.

[0235] Examples of compounds having a hydroxyl group as an active hydrogen group include alkanols such as octanol and decanol, aliphatic diols such as 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, 3,3-dimethylolheptane, octanediol, and decanediol, alicyclic alcohols such as 1,3- or 1,4-cyclohexanedimethanol and 1,3- or 1,4-cyclohexanediol, aromatic alcohols such as salicylic alcohol and vanillyl alcohol, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, and 2,6- Examples of the alcohol include dihydric alcohols such as dimethyl-1-octene-3,8-diol, bisphenol A, diethylene glycol, triethylene glycol, and dipropylene glycol; trihydric alcohols such as glycerin, trimethylolpropane, and triisopropanolamine; tetrahydric alcohols such as tetramethylolmethane (pentaerythritol) and diglycerin; pentahydric alcohols such as xylitol; hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altritol, inositol, and dipentaerythritol; and heptahydric alcohols such as perseitol.

[0236] Examples of compounds having an amino group as an active hydrogen group include aliphatic amines such as octylamine, decaneamine, 1,8-diaminooctane, and 1,10-diaminodecane; alicyclic amines such as isophoronediamine, norbornenediamine, bis(aminomethyl)cyclohexane, cyclohexanediamine, diaminodicyclohexylmethane, and methylenebis(methylcyclohexaneamine); and aromatic amines such as 1-xylylenediamine, N-benzylethylenediamine, phenylenediamine, diaminodiphenylmethane, diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, toluenediamine, and diethyltoluenediamine.

[0237] Examples of compounds having an SH group as an active hydrogen group include hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, undecyl mercaptan, and dodecyl mercaptan. , tridecyl mercaptan, tetradecyl mercaptan, pentadecyl mercaptan, mercaptophenol, mercaptopropionic acid, mercaptobutyric acid, 1,4-butanedithiol, 2-mercaptobenzothiazole, 3-mercapto-1,2-propanediol, mercaptomethylbutanol, 3-mercapto-2-methylpentanol, 3-mercapto-3-methylbutanol, 4-ethoxy-2-methyl-2-butanethiol, hexanethiol, dimethylthiophenol, 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptobutyrate), etc.

[0238] The compound having active hydrogen may be used alone or in combination of two or more kinds. Isosorbide, tris(2-hydroxyethyl) isocyanurate, trimethylolpropane, dipentaerythritol, and 1,4-cyclohexanedimethanol are preferred.

[0239] The amount of the compound having active hydrogen is preferably 0.5% by mass or more and 20% by mass or less based on the solid content of the barrier coating agent (3).

[0240] The barrier coating agent (3) may further contain a layered inorganic compound, an acid anhydride, an oxygen scavenger, an inorganic filler, and when an inorganic material is used, a dispersant, a stabilizer (antioxidant, heat stabilizer, ultraviolet absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, a leveling agent, a slip improver, etc.

[0241] The barrier coating agent (3) may be diluted with an organic solvent, such as ester solvents like ethyl acetate, propyl acetate, and butyl acetate, ketone solvents like acetone and 2-butanone, ether solvents like tetrahydrofuran, aliphatic solvents like hexane and cyclohexane, and aromatic solvents like toluene.

[0242] (heat-resistant coating layer) The laminate of the present invention may include layers other than those described above. One example of such a layer is a heat-resistant coating layer. The heat-resistant coating layer has a function of improving the heat resistance of the laminate of the present invention, and can be provided at any position on the laminate of the present invention by applying and drying a heat-resistant coating agent.

[0243] Taking the laminate of the present invention as an example for use as a packaging component for packaging contents, if the outermost substrate of a bag filled with contents is a film with low heat resistance, such as a polyethylene film or a polypropylene film, there is a risk of shrinkage due to heat when the laminate is made into a bag by heat sealing. This problem can be prevented by providing a heat-resistant coating layer. The heat-resistant coating layer is preferably disposed outside the outermost substrate of the substrates constituting the laminate when viewed from the contents after the bag is made. For example, when the first substrate is the outermost substrate of the substrates constituting the laminate of the present invention, the heat-resistant coating layer is preferably disposed on the surface of the first substrate opposite the adhesive layer.

[0244] Examples of heat-resistant coating agents include coating agents containing compounds having a cellulose skeleton, a benzene ring skeleton, an isocyanuric ring skeleton, or an alicyclic skeleton, whose homopolymer glass transition temperature (hereinafter sometimes referred to as Tg) is 100° C. or higher. Specific examples of such compounds 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 an ethylene oxide (hereinafter sometimes referred to as EO) adduct of bisphenol A, and / or an alicyclic skeleton such as cyclopentanediol and dimethyloltricyclodecane; and urethane resins obtained by combining aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalenediisocyanate; alicyclic isocyanates such as isophorone diisocyanate and norbornene diisocyanate; and / or isocyanuric triisocyanate with a polyol and / or tris(2-hydroxyethyl)isocyanurate. Polyisocyanates using the aforementioned isocyanates may also be used as curing agents. 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, in consideration of adhesion to olefin films, a resin with a low Tg may be mixed in.

[0245] The heat-resistant coating agent preferably uses inorganic fine particles such as alumina, magnesia, titania, zirconia, and silica (quartz, fumed silica, precipitated silica, silicic anhydride, fused silica, crystalline silica, and ultrafine amorphous silica) as aggregates because they have excellent heat resistance. Alternatively, boron nitride, aluminum nitride, alumina oxide, titanium oxide, magnesium oxide, zinc oxide, and silicon oxide are preferred because they have excellent thermal conductivity. The inorganic fine particles may be used alone or in combination.

[0246] The shape of the silica fine particles is not particularly limited, and spherical, hollow, porous, rod-like, plate-like, fibrous, or irregularly shaped particles can be used. For example, commercially available hollow silica fine particles such as Silinax manufactured by Nittetsu Mining Co., Ltd. can be used.

[0247] The primary particle diameter of the inorganic fine particles is preferably in the range of 5 nm to 200 nm, and more preferably 10 nm to 100 nm. The inorganic fine particles can be blended in a proportion of 5 to 90% by weight based on the total solid content of the heat-resistant coating agent and the inorganic fine particles, and the blending amount may be changed as needed depending on the purpose. In particular, 20% by weight or more is preferred.

[0248] The heat-resistant coating agent 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 described below.

[0249] Waxes, silicon additives, and organic beads can be used for the heat-resistant coating agent.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 silicon-modified products, and organic beads made of acrylic, nylon, urethane, or epoxy can be added.

[0250] The solvent used in the heat-resistant coating agent is not particularly limited, but examples 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-based 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. Antifoaming agents and leveling agents may also be used to more effectively coat the film.

[0251] Commercially available heat-resistant coating agents can also be used, such as SUNSYS FS241 manufactured by Sun Chemical, DH-004 / DH-HARDENER P-60 manufactured by DIC, and ThermaGloss 463 manufactured by Michelman.

[0252] <Packaging material> The laminate of the present invention can be used as a multilayer packaging material for the purpose of protecting food, medicines, etc. When used as a multilayer packaging material, the layer structure can be changed depending on the contents, the environment of use, and the form of use.

[0253] The packaging material of the present invention can be obtained, for example, by overlapping the heat-sealable layers of the laminate of the present invention so that they face each other, and then heat-sealing the peripheral edges. Examples of bag-making methods include folding or overlapping the laminate of the present invention so that the inner layer surfaces (sealant film surfaces) face each other, and heat-sealing the peripheral edges using, for example, a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a flared seal type, a flat-bottom seal type, a square-bottom seal type, a gusset seal type, or other heat seal type. The packaging material of the present invention can take various forms depending on the contents, usage environment, and usage form. Self-standing packaging materials (standing pouches) are also possible. Heat-sealing methods can be known, such as bar seal, rotary roll seal, belt seal, impulse seal, high-frequency seal, and ultrasonic seal.

[0254] The packaging material of the present invention is filled with contents through its opening, and the opening is then heat-sealed to produce a product using the packaging material of the present invention. The contents to be filled include confectioneries such as rice crackers, bean snacks, nuts, biscuits, cookies, wafer snacks, marshmallows, pies, semi-dried cakes, candies, and snack foods; staple foods such as bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged cooked rice, porridge, 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 fish ham and sausages. Examples of suitable packaging materials include processed seafood products such as fish paste products, kamaboko (fish paste), nori (seaweed paste), tsukudani (simmered foods in soy sauce), dried bonito flakes, salted fish, smoked salmon, and spicy cod roe, fruit pulp such as peaches, mandarin oranges, pineapples, apples, pears, and cherries, vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes, prepared foods such as frozen and chilled prepared foods, including hamburger steaks, meatballs, fried seafood, gyoza (dumplings), and croquettes, dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula, liquid seasonings, retort curry, and pet food. The packaging material of the present invention can also be used as a packaging material for cigarettes, pharmaceuticals such as disposable body warmers and infusion packs, cosmetics, and vacuum insulation materials.

[0255] <Recycling method> The laminate of the present invention and packaging materials made from the laminate have excellent recyclability and can be used as raw materials for recycled plastics. The recycled plastics of the present invention are those recycled using the laminate and packaging materials of the present invention as raw materials. The recycled plastics of the present invention can be obtained, for example, by peeling the laminate and packaging materials of the present invention into their respective substrates (peeling process), separating them by resin type (separation and recovery process), melt-kneading them, and then pelletizing them.

[0256] (peeling process) The laminate and packaging material of the present invention can be immersed in a release agent for a certain period of time, whereby the adhesive or printing ink is released from the substrate and separated into a single-layer film. Examples of the release agent include an aqueous solution of a basic compound. The release agent may further contain a hydrophilic alcohol, a surfactant, an antifoaming agent, and other additives.

[0257] When a film having a vapor-deposited layer of a metal or metal oxide is used as the substrate, it is preferable to use a release agent containing a basic compound, as this dissolves these layers, making it easier to peel the laminate, and also reducing the effect on the physical properties of the recycled pellets.

[0258] As the water, pure water such as tap water, ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water can be used. From the viewpoint of long-term storage, it is preferable to use water that has been sterilized by ultraviolet irradiation or addition of hydrogen peroxide, etc., because this can prevent the growth of mold or bacteria. When using a stripping agent containing a basic compound, it is preferable to use water with a hardness of 120 ppm or less, and more preferably water with a hardness of 80 ppm or less.

[0259] Examples of basic compounds include sodium hydroxide, potassium hydroxide, sodium carbonate, and calcium hydroxide. When the stripping agent contains a basic compound, the concentration of the basic compound is preferably 0.01% by mass or more and 5% by mass or less. The basic compound is adjusted so that the pH of the stripping agent is about 10 to 14.

[0260] The hydrophilic alcohol is an aliphatic alcohol that can be mixed with water in any ratio. Examples of hydrophilic alcohols include methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, and glycerin. These can be used alone or in combination of two or more, with ethanol being preferred. When the release agent contains a hydrophilic alcohol, its content is preferably 1% by mass or more and less than 60% by mass of the release agent.

[0261] Examples of surfactants include anionic surfactants such as 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;

[0262] nonionic surfactants such as 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;

[0263] cationic surfactants such as alkyltrimethylammonium salts, alkylPG trimethylammonium salts, alkyldimethylbenzylammonium salts, alkylamidoamines, alkylPG dimethylamines, and cationic polymers;

[0264] amphoteric surfactants such as alkyl betaines, alkylamido betaines, imidazolinium betaines, and amine oxides;

[0265] Silicone surfactants such as polysiloxane oxyethylene adducts; fluorine surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; Examples include biosurfactants such as spiculisporic acid, rhamnolipid, and lysolecithin.

[0266] 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 release agent.

[0267] Examples of antifoaming agents include water-soluble organic solvents and nonionic surfactants with an HLB value in the range of 1 to 3, which can be used alone or in combination of two or more. Silicone compounds, especially emulsion-type or self-emulsifying silicone compounds, are preferably used. When an antifoaming agent is added, the amount added is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and even more preferably 0.01 to 1% by mass, based on the total amount of the release agent.

[0268] The immersion time in the release agent is not particularly limited, but is, for example, 10 minutes or more and less than 5 hours. The immersion step in the release agent may be performed only once or may be performed multiple times. When the immersion step is performed multiple times, the release agents used may be the same or different.

[0269] The peeling of the laminate and packaging material is preferably carried out by heating to a temperature of 55° C. to 85° C., more preferably 70° C. to 85° C. The heating method is not particularly limited, and known heating methods such as those using heat rays, infrared rays, microwaves, etc. can be used. The treatment tank used for immersion in the stripping agent is preferably equipped with a reflux condenser for refluxing the heated and evaporated stripping agent.

[0270] The release agent is preferably stirred during immersion in the release agent. Examples of stirring methods include mechanically stirring the dispersion of the laminated film contained in a treatment tank with a stirring blade, water-jet stirring with a water pump, and bubbling with an inert gas such as nitrogen gas. Several methods may also be used in combination. This allows for more efficient separation of the laminate.

[0271] During the immersion in the stripping agent, ultrasonic vibrations may be applied to the stripping solution, for example, by attaching an ultrasonic vibrator to the treatment tank.

[0272] (Sorting and collection process) The release agent that has undergone the peeling process contains floating or dissolved adhesive and printing ink that have been peeled off from the laminate, film pieces (first substrate, second substrate, etc.) that have become single layers when the laminate is separated by the peeling of the adhesive, and metal pieces (if the laminate contains a metal layer or a metal vapor deposition layer). In the sorting and recovery process, these are removed from the release agent and sorted and recovered.

[0273] As an example of a specific method, for example, flotation separation is used to separate light plastics such as polyolefins like polypropylene and polyethylene (floating matter) from heavy materials such as condensed synthetic films like polyester and nylon, which have a higher specific gravity than polyolefins, or metal foil, and then the heavy materials are removed. The recovered plastics are then washed and dehydrated, and then centrifuged to separate plastics with different specific gravities. For example, plastics can be separated into plastics containing vinyl chloride resins and polyethylene terephthalate, which have a specific gravity of 1 or more, that sink in water, and plastics containing olefin-based resins such as polyethylene and polypropylene, which do not contain vinyl chloride resin. By appropriately changing the mixing ratio of the liquid used for separation, for example, water and organic solvent, film pieces with various different specific gravities can be separated and recovered.

[0274] (Reuse of remover) The release agent used in the laminate peeling step is preferably recovered and reused after removing components other than the film pieces, such as adhesive layer pieces and printed layer pieces peeled from the laminate. Examples of a method for removing components other than the film pieces include filtration.

[0275] Components such as adhesive layer fragments and printed layer fragments can be pulverized by shear forces applied by stirring, which is often performed in the peeling process. If the adhesive layer fragments and printed layer fragments are pulverized too much in the peeling process, they may not be able to be filtered out completely depending on the opening size of the filter, and the adhesive layer fragments and printed layer fragments may remain in the release agent after filtration, causing the release agent to become discolored. If a filter with a small opening size is used to suppress discoloration of the release agent after filtration, the filtration will take a long time.

[0276] In the laminate of the present invention (and the packaging material obtained by making a bag from the laminate), the printed layer is sandwiched between the above-mentioned release layer and adhesive layer, and after the printed layer and adhesive layer are peeled from the first substrate and the second substrate, they are not too finely divided, and pieces of the printed layer and adhesive layer can be recovered even with a filter with a relatively large opening diameter, allowing the release agent to be filtered efficiently. This is also true when the laminate of the present invention includes a third substrate.

[0277] The opening size of the filter is adjusted appropriately in consideration of the filtration efficiency of the release agent and the coloration degree of the release agent after filtration, and is, for example, 10 μm to 200 μm. According to the present invention, the opening size of the filter used to filter the release agent can be, for example, 30 μm to 200 μm, for example, 50 μm to 200 μm, or for example, 100 μm to 200 μm.

[0278] (pelletization) The film pieces collected by resin type in the separation and collection process are heated and melted at 120 to 280°C and then kneaded. The melting temperature can be adjusted taking into account the glass transition temperature and melting temperature of the resin, the shape when pelletized, and the pressure applied in the molding process. The screw rotation speed during kneading is, for example, 50 to 1000 RPM.

[0279] The melt-kneaded film pieces are cooled and shredded to form recycled plastic pellets. Examples of pelletizing methods include, but are not limited to, hot cutting and strand cutting. To prevent foreign matter from being mixed into the pellets, it is preferable that a screen mesh be provided at the discharge section of the melt-kneaded laminate or packaging material. Examples of screen mesh include plain weave, twill weave, plain dutch weave, and twill dutch weave, as well as punched metal types. Taking into consideration the pressure and clogging of the discharge section, the screen mesh size is preferably 40 mesh or larger, more preferably 80 mesh or larger, and even more preferably 120 mesh or larger. Examples of cooling methods include air cooling, wind cooling, and water cooling. In the present invention, a water cooling step is preferably included. Cooling to 20°C to 80°C is preferable, and cooling to 30°C to 60°C is more preferable.

[0280] The recycled plastic of the present invention may contain known additives, such as at least one antioxidant selected from the group consisting of phenolic and phosphorus-based additives, at least one lubricant selected from the group consisting of fatty acid amides, alkylene fatty acid amides, metal soaps, and esters, a hindered amine weathering stabilizer, a wax having an acid value of 5 mgKOH / g or less, and at least one antistatic agent selected from the group consisting of fatty acid sulfonates and fatty acid esters.

[0281] The recycled plastic of the present invention may contain virgin plastic as a raw material in addition to the laminate and packaging material of the present invention. The virgin plastic to be added is of the same resin type as the film pieces. The virgin plastic may be added when pelletizing the film pieces, or when molding the pelletized recycled plastic of the present invention. The virgin plastic may be added both when pelletizing and when molding the recycled plastic. The amount of virgin plastic used in combination when pelletizing the film pieces is, for example, in the range of 100:0 to 25:75 (mass ratio) of film pieces:virgin plastic. The amount of virgin plastic used when molding the pelletized recycled plastic of the present invention is, for example, in the range of 100:0 to 25:75 (mass ratio) of recycled plastic:virgin plastic.

[0282] (Crushing process) A crushing step of the laminate may be carried out prior to the step of immersing the laminate in the release agent. This allows for an increased area of ​​the edge surface of the laminate that comes into contact with the release agent, thereby shortening the time required to peel the laminate. On the other hand, the separated laminate may then be separated by gravity sorting or the like, and it is preferable that the film pieces are not too small. Taking these factors into consideration, it is preferable that in the crushing step, the laminate is crushed (including cutting) into small rectangular pieces with sides of approximately 5 to 60 mm. The crushing method may be so-called wet crushing, in which crushing is carried out in water or a cleaning solution, or dry crushing, in which crushing is carried out in an air atmosphere without the presence of a liquid such as a solvent.

[0283] The wet crusher is not particularly limited, but is preferably one that can crush, disperse, mix, and pump solids in a liquid simultaneously. Specifically, it is preferably one that has a mechanism for crushing solids in a liquid using shear force and / or friction force, and is also preferably a crusher that has a mechanism for crushing and pumping plastic films. Examples of such wet crushers include wet crushing pumps, colloid mills, and attritors.

[0284] The dry crusher is not particularly limited, but examples of the dry crusher that can be used include a mycoloider, a mass colloider, a ball mill, a power mill, a pin mill, an airflow crusher (jet mill), a shear friction crusher, a cutter crusher, an impact crusher (hammer mill, ball mill), a roll crusher, a homogenizer, and an ultrasonic crusher.

[0285] (Cleaning process) The crushed laminate pieces are preferably subjected to a washing process before being sent to the peeling process. In the washing process, the pieces are placed in a washing vessel containing a washing liquid such as water or a detergent solution, and stirred in the washing vessel to wash away organic matter (food residue, grease stains, etc.) and inorganic matter (sand, dust, etc.) adhering to the laminate. Next, the laminate pieces are transferred to a rinsing vessel containing rinsing water, rinsed, and then drained.

[0286] (Application) The recycled plastic of the present invention can be used as a raw material for various plastic products. Examples of plastic products include, but are not limited to, transportation pallets and containers, containers such as bottles, hangers, stationery, pots and cups, disposable cutlery, and play equipment. The recycled plastic can also be recycled as film, or the recycled film can be molded and used as, for example, cushioning material for transporting fruit, but is not limited to this. [Example]

[0287] The present invention will be described in more detail below with reference to specific synthesis examples and 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.

[0288] <Preparation of coating agent> A coating agent was prepared according to the formulation shown in Table 1. The compounds used in preparing the coating agent are as follows. (Polyvinyl alcohol 1) Nichigo G-polymer (AZF8035Q), manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 24,000, solid content 100% (Polyvinyl alcohol 2) Polyvinyl alcohol with a vinyl acetate-derived structure / ethylene-derived structure / propylene-derived structure = 96 / 3 / 1 (mol%), weight average molecular weight 48,000, solid content 100% (Polyethyleneimine) Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd., solid content 30%

[0289] [Table 1]

[0290] Polyvinyl alcohols 1 and 2 are soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C to a concentration of 5% by mass or more, and a solution in which 5% by mass of the vinyl alcohol polymer is dissolved in a 1:1 (mass ratio) solution of water and ethanol has a viscosity of 200 mPa s or less at 25°C.

[0291] The PEI content in the table refers to the polyalkyleneimine content relative to the total amount of polyvinyl alcohol and polyalkyleneimine used to prepare the coating agent. In the table, Tg refers to the glass transition temperature of the dried coating film of each coating agent. In the table, viscosity refers to the viscosity of each coating agent at 25°C.

[0292] <Preparation of adhesive> (Adhesive 1) Adhesive 1 was prepared by mixing 60 parts of DIC DRY® LX-500, an ester urethane solvent-based adhesive manufactured by DIC Corporation, and 1 part of KW-75, and diluting the mixture with ethyl acetate. (Adhesive 2-7) Adhesives 2 to 7 were prepared by adding acid anhydrides to adhesive 1 in the proportions shown in Table 2. The values ​​in the table represent the amount of acid anhydride added per 100 parts by mass of the solid content of adhesive 1.

[0293] (Adhesive 8~11) A mixture of 1 part of DIC DRY (registered trademark) LX-470EL, an ether-based solvent-based adhesive manufactured by DIC Corporation, and 1 part of SP-60 was diluted with ethyl acetate, and acid anhydrides were added in the proportions shown in Table 3 to prepare adhesives 8 to 11. The values ​​in the table represent the amount of acid anhydride added per 100 parts by mass of the solid content of the adhesive.

[0294] (Adhesive 12~15) Adhesives 12 to 15 were prepared by mixing 10 parts of DIC DRY (registered trademark) NS-5210A, an ester-based solventless adhesive manufactured by DIC Corporation, and 7 parts of HA-520B, to which acid anhydrides were added in the proportions shown in Tables 3 and 4. The values ​​in the tables represent the amount of acid anhydride added per 100 parts by mass of the solid content of the adhesive.

[0295] (Adhesive 16-19) Adhesives 16 to 19 were prepared by mixing 10 parts of DIC DRY (registered trademark) SF-220A, an ether-based solventless adhesive manufactured by DIC Corporation, and 7 parts of HA-233B, to which acid anhydrides were added in the proportions shown in Table 4. The values ​​in the table represent the amount of acid anhydride added per 100 parts by mass of the solid content of the adhesive.

[0296] The acid anhydrides used in preparing the adhesives are as follows: (B-4500) EPICLON® B-4500, a product of DIC Corporation, 3a, 4, 5, 7a-tetrahydro-7-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-1,3-isobenzofurandione (SMA 1000) SMA® Resin 1000, a product of CRAYVALLY, a 1 / 1 styrene / maleic anhydride copolymer (SMA 2000) SMA® Resin 2000, a product of CRAYVALLY, a 2 / 1 styrene / maleic anhydride copolymer (SMA 3000) SMA® Resin 3000, a product of CRAYVALLY, a 3 / 1 styrene / maleic anhydride copolymer

[0297] [Table 2]

[0298] [Table 3]

[0299] [Table 4]

[0300] <Manufacturing of laminate> Example 1 The first substrate was coated with a coating weight (solids) of 0.5 g / m using a gravure printing machine equipped with a gravure plate with a plate depth of 22 μm. 2 The coating agent 1 was applied in a solid layer so that the thickness became 1 / 2 mm, and the coating agent was dried by passing it through an oven at 70°C, and then left at room temperature for one day to form a release layer.

[0301] Next, adhesive 2 was applied onto the release layer, and the resultant was attached to a second substrate, followed by aging at 40°C for 3 days to obtain a laminate of first substrate / release layer / adhesive layer / second substrate.

[0302] Example 2 A release layer was provided on the first substrate in the same manner as in Example 1. Next, a urethane-based laminating ink (Finart R794 white, manufactured by DIC Corporation) was adjusted to 15 seconds (25°C) using a Zahn Cup #3 manufactured by Rigo Co., Ltd., and printed solidly on the release layer using a gravure printing machine equipped with a gravure plate with a plate depth of 43 μm. The ink was then dried or cured by passing through an oven at 70°C to form a printed layer.

[0303] Next, an adhesive was applied onto the printed layer (the solvent-based adhesive was allowed to dry), and the printed layer was laminated to a second substrate, followed by aging at 40°C for 3 days to obtain Example 2, which consisted of a first substrate / release layer / printed layer / adhesive layer / second substrate.

[0304] Examples 3 to 30 The coating agent, adhesive, and first substrate used in producing the laminate were changed as shown in Tables 5 to 7 to produce laminates of Examples 3 to 30.

[0305] (Comparative Examples 1 to 20) The coating agent, adhesive, and first substrate used in producing the laminate were changed as shown in Tables 8 and 9 to produce laminates of Comparative Examples 1 to 20.

[0306] The first substrate and the second substrate used in the production of the laminate were as follows. (First substrate) OPP: Toyobo Co., Ltd., P2161 (film thickness 20 μm) PET: Toyobo Co., Ltd., E5100 (film thickness 12 μm) (Second substrate) CPP: Toyobo Co., Ltd., P1128 (film thickness 30 μm)

[0307] Adhesives 1 to 11 have a coating amount (solid content) of 2.5 g / m 2 After the adhesive was applied, the solvent was dried with a dryer before bonding to the second substrate. Adhesives 12 to 19 have a coating amount (solid content) of 2.5 g / m 2 In addition, adhesives 12 to 19 were not dried with a dryer because they did not substantially contain a solvent.

[0308] <Evaluation> (Laminate strength) The laminates of the Examples and Comparative Examples were cut into test pieces of 300 mm in length and 15 mm in width. Using an Instron tensile tester, the test pieces were pulled at a peel rate of 300 mm / min in an environment of 25°C, and the T-peel strength (N) was measured. This test was carried out five times, and the average value was calculated and evaluated according to the following criteria. The results are summarized in Tables 5 to 9. 〇: 0.5N / 15mm or more ×: Less than 0.5N / 15mm

[0309] (Delamination property) The laminates of the Examples and Comparative Examples were cut into 20 mm x 20 mm test pieces. The test pieces were immersed in Treatment Solution 1 (2% NaOH aqueous solution) at 70°C and stirred at 400 rpm using a magnetic stirrer for 1 hour, after which the test pieces were removed. After washing with ion-exchanged water and drying, the peeled area (%) of the adhesive was measured and evaluated according to the following criteria. The results are summarized in Tables 5 to 9. The delamination properties were evaluated in the same manner as above, except that Treatment Solution 2 (a 1% NaOH aqueous solution to which 0.3% by mass of polyethylene glycol t-octylphenyl ether had been added) was used instead of Treatment Solution 1, and the results are summarized in Tables 5 to 9. 5: The first substrate and the second substrate are completely peeled off, and the printing layer and adhesive layer are completely peeled off from both the first substrate and the second substrate. 4: 100% peeling of the first substrate 3: The peeling area between the first substrate and the second substrate is 50% or more but less than 100% 2: The peeling area between the first substrate and the second substrate is 10% or more but less than 50% 1: The peeling area between the first and second substrates is less than 10%

[0310] (Recyclability) After the delamination test, the release agent was filtered through a nylon strainer with 90 mesh / inch and an opening diameter of 185 μm, and the condition of the filtered laminate sample and the presence or absence of coloration of the release agent after filtration were visually checked. The results were evaluated using the following two-level scale and are summarized in Tables 5 to 9. 〇: The first substrate, second substrate, printed layer pieces, and adhesive pieces can be recovered separately. No coloring is observed in the release agent after filtration. ×: The first substrate, the second substrate, the printed layer piece, and the adhesive piece could not be recovered separately, and coloring was observed in the release agent after filtration.

[0311] [Table 5]

[0312] [Table 6]

[0313] Table 7

[0314] Table 8

[0315] Table 9

Claims

1. a first substrate; a second substrate; and a release layer disposed between the first substrate and the second substrate, the release layer including a vinyl alcohol polymer and a polyalkyleneimine; an adhesive layer disposed between the release layer and the second substrate, the adhesive layer being a cured coating film of an adhesive containing an acid anhydride, the adhesive being a two-component curing adhesive containing a polyol composition containing a polyol and a polyisocyanate composition containing a polyisocyanate compound, the polyol containing a polyester polyol, and the amount of the acid anhydride blended being 0.1% by mass or more and 10% by mass or less of the total amount of the polyol and the polyisocyanate compound; a printed layer disposed between the release layer and the adhesive layer.

2. A recycling method including a peeling step of immersing the laminate described in claim 1 in a peeling agent to peel off the first substrate and the second substrate.

3. The recycling method according to claim 2, wherein the release agent is heated to a temperature of 55°C or higher and 85°C or lower.

4. 3. The recycling method according to claim 2, wherein the stripping agent is an aqueous solution of a basic compound.

5. 3. The recycling method according to claim 2, wherein the release agent is recovered and filtered through a filter having an opening diameter of 10 μm or more and 200 μm or less before being reused.

6. a separation and recovery step of recovering the first substrate from the release agent that has been subjected to the peeling step; The recycling method according to claim 2, further comprising a pelletizing step of melting and kneading the first base material recovered in the separating and recovering step.

7. The recycling method according to claim 6, wherein in the pelletizing step, the first substrate recovered in the separating and recovering step and virgin plastic of the same resin type as the first substrate are melted and kneaded.

8. 8. The recycling method according to claim 7, wherein the mass ratio of the first substrate to the virgin plastic is 100:0 to 25:

75.

9. Recycled pellets obtained by the recycling method according to claim 6.

10. A plastic product molded from the recycled pellets according to claim 9.

11. A plastic product made from the recycled pellets of claim 9 and virgin plastic of the same type of resin as the recycled pellets.

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