Laminates, packaging materials, recycling methods

Abstract

Provided are: a laminate capable of being detached under a mild condition and being produced by a general-purpose method, and exhibiting excellent adhesive strength; a recycling method for the laminate; and a recycled plastic obtained from the laminate.　This laminate includes: a first base material; a second base material; an adhesive layer disposed between the first base material and the second base material; and a first resin layer disposed between the first base material and the adhesive layer. The first resin layer contains a first vinyl alcohol-based polymer and a first polyalkyleneimine. The first vinyl alcohol-based polymer can be dissolved in a 1:1 (mass ratio) solution of water and ethanol in an amount of 5 mass% or more at 25°C, and the solution obtained by dissolving the vinyl alcohol-based polymer in the 1:1 (mass ratio) solution of water and ethanol in an amount of 5 mass% has a viscosity of 200 mPa･s or less at 25°C. The glass transition temperature of the first resin layer is 40-80°C.

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] Traditionally, the mandatory recycling of plastic containers and packaging has led to the collection, sorting, and reuse of plastic waste, including food packaging. Plastic waste comes in many forms, including synthetic resins such as polyethylene, polypropylene, polystyrene (expanded polystyrene), polyethylene terephthalate, and polyvinyl chloride, as well as laminated films made by layering these synthetic resin films or metal foils such as aluminum foil, and then printing them with ink to display product names or other decorative elements. These materials are often mixed together when collected as waste.

[0003] Generally, waste plastics containing both thermoplastic and thermosetting resins can be separated by specific gravity and recycled, but the ease of recovery varies depending on the resin. Furthermore, many packaging materials, including those for food packaging, are made by bonding different synthetic resins together with adhesives, making separation difficult using this method. It is generally recognized that recycling thermosetting resins is difficult due to their low thermal decomposition rate. Laminated films with printed inks for product names, etc., or decorative purposes may not have the printing ink completely separated during the recycling process, resulting in recycled products that are discolored or retain the printed pattern.

[0004] Patent Document 1 discloses a method for separating and recovering such complex waste by processing each component, comprising the steps of: using triethylene glycol as a separation solvent, adding alkali metal hydroxide as a catalyst, heating the triethylene glycol to 250-280°C (near its boiling point) above 200°C, and melting component P1 that can be melted in the triethylene glycol; dissolving or depolymerizing component P2 that is difficult to melt under heat in triethylene glycol heated to 250-280°C under stirring and discharging it together with the solvent; recovering the remaining molten component P1 and reinforcing fiber F or metal component M; recovering the non-molten component P2 and separation solvent, and distilling the separation solvent under reduced pressure to separate it from the non-molten component P2, purifying it, and reusing it. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-110531 [Overview of the project] [Problems that the invention aims to solve]

[0006] To allow for milder delamination of laminated films, the placement of a detachable primer layer between the film and the adhesive layer (or printed layer) has been considered. However, the addition of such a primer layer may reduce the adhesive strength between the films. Alternatively, depending on the type of resin used to form the primer layer, efficient formation of the primer layer may be difficult using general manufacturing methods.

[0007] This invention has been made in view of these circumstances, and aims to provide a laminate that can be peeled off under mild conditions, has excellent adhesive strength, and can be manufactured by a general method, a method for recycling the laminate, and recycled plastic obtained from the laminate. [Means for solving the problem]

[0008] The present invention relates to a laminate comprising a first substrate, a second substrate, an adhesive layer disposed between the first substrate and the second substrate, and a first resin layer disposed between the first substrate and the adhesive layer, wherein the first resin layer comprises a first vinyl alcohol polymer and a first polyalkylene imine, the first vinyl alcohol polymer is soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, the viscosity of 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 at 25°C is 200 mPa·s or less, and the glass transition temperature of the first resin layer is 40°C or higher and 80°C or lower. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminate that can be peeled off under mild conditions, has excellent adhesive strength, and can be manufactured by a general method, a method for recycling the laminate, and recycled plastic obtained from the laminate. [Modes for carrying out the invention]

[0010] <Laminate> The laminate of the present invention comprises a first substrate, a second substrate, an adhesive layer disposed between the first substrate and the second substrate, and a first resin layer disposed between the first substrate and the adhesive layer. The laminate of the present invention will be described in detail below.

[0011] (First base material) The first substrate can be used without particular limitation as long as it is a film or sheet excellent in chemical and physical strength (hereinafter, unless otherwise specified, the film also includes both films and sheets). 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 stretched polyethylene film, OPE: biaxially stretched polyethylene film), polypropylene film (CPP: unstretched polypropylene film, OPP: biaxially stretched polypropylene film), ethylene vinyl alcohol copolymer, and polyolefin films such as gas barrier films obtained by providing an olefin-based heat-sealable resin layer on one or both sides of a resin having gas barrier properties such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer film, etc.

[0012] It is also preferable to use a film formed of a material containing biomass-derived components. Biomass films are sold by various companies. For example, sheets such as those listed in the list of biomass-certified products described by the Japan Organic Resources Association, a general incorporated foundation, can be used.

[0013] Specifically, well-known films are those 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 a method of producing ethylene glycol via ethylene oxide from biomass ethanol by a conventionally known method. Also, commercially available biomass ethylene glycol may be used. For example, biomass ethylene glycol commercially available from Indiaglycol Co., Ltd. can be preferably used.

[0014] Alternatively, products using biomass raw materials distinguished by the biomass plastic content defined in ISO 16620 or ASTM D6866 are also in circulation. Radiocarbon 14C exists in the atmosphere at a ratio of 1 in 1012, and this ratio remains unchanged even in atmospheric carbon dioxide. Therefore, this ratio also remains unchanged in plants that have fixed this carbon dioxide through photosynthesis. For this reason, the carbon in plant-derived resins contains radiocarbon 14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radiocarbon 14C. Therefore, by measuring the concentration of radiocarbon 14C in the resin using an accelerator mass spectrometer, the content ratio of plant-derived resin in the resin, that is, the biomass plastic content, can be determined. Examples of plant-derived low-density polyethylene that is a biomass plastic with a biomass plastic content of 80% or more, preferably 90% or more, as defined in ISO 16620 or ASTM D6866, include products named "SBC818", "SPB608", "SBF0323HC", "STN7006", "SEB853", "SPB681", etc. manufactured by Braskem, and films using these as raw materials can be preferably used.

[0015] The film may be subjected to a stretching treatment. As a stretching treatment method, it is common to melt-extrude the resin into a sheet shape by an extrusion film-forming method or the like, and then perform simultaneous biaxial stretching or sequential biaxial stretching. In the case of sequential biaxial stretching, it is general to first perform a longitudinal stretching treatment and then a transverse stretching. Specifically, a method combining longitudinal stretching using the speed difference between rolls and transverse stretching using a tenter is often used.

[0016] If necessary, various surface treatments such as flame treatment or corona discharge treatment may be performed on the film surface so that an adhesive layer without defects such as film breakage or repulsion is formed.

[0017] Alternatively, inorganic vapor-deposited films such as metal vapor-deposited films with a metal layer such as aluminum, or transparent vapor-deposited films with laminated layers of metal oxides 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 preferable because, in the recycling process described later, if the stripping solution used to separate the laminate contains a basic compound, the vapor-deposited layer dissolves more easily in the stripping solution, making it easier to peel the printed layer and adhesive from the resin film.

[0018] The film thickness of the first substrate is not particularly limited and can be appropriately selected within the range of 1 to 300 μm from the viewpoint of moldability and transparency. Preferably, it is in the range of 1 to 100 μm.

[0019] (Second base material) The second substrate can be the same as the first substrate. In one embodiment of the present invention, the second substrate is a heat-sealable film (sealant film) that can melt and fuse with each other by heat, and the first substrate is a substrate that is not expected to act as a sealant film. In another embodiment of the present invention, the second substrate is a film in which a film that does not have heat-sealability and a heat-sealable resin layer (heat-seal layer) are laminated, and the first substrate is a substrate that is not expected to act as a sealant film.

[0020] 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-(meth)acrylate ethyl copolymer, ethylene-propylene copolymer, methylpentene polymer, modified olefin resins obtained by modifying olefin resins such as polyethylene or polypropylene with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids, ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid terpolymer, cyclic polyolefin, cyclic olefin copolymer, polyethylene terephthalate (PET), polyacrylonitrile (PAN), ethylene vinyl alcohol copolymer, and gas barrier resins such as polyvinyl alcohol, with an olefin-based heat-sealable resin layer on one or both sides. Films, sheets, and other coated films made from one or more of these resins can be used as sealant films.

[0021] Any type of sealant film can be used, including unstretched, uniaxially oriented, and biaxially oriented films.

[0022] A biaxially stretched film can be obtained, for example, by longitudinally stretching it 2 to 4 times using a roll stretcher at 50 to 100°C, then transversely stretching it 3 to 5 times using a tenter stretcher in an atmosphere of 90 to 150°C, and subsequently heat-treating it using a tenter stretcher in an atmosphere of 100 to 240°C. Alternatively, films that have been simultaneously biaxially stretched or sequentially biaxially stretched may be used.

[0023] An easy-peel sealant film may be used as the sealant film. Any type of easy-peel sealant film can be applied, including interfacial peel type, cohesive peel type, and interlayer peel type, and can be appropriately selected according to the type of packaging material and required characteristics described later. The indicator of easy peelability is set appropriately according to the type of packaging material and required characteristics, but one 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 combining polypropylene with high-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, etc.

[0024] If the second substrate is a film in which a film that does not have heat-sealing properties and a resin layer that does have heat-sealing properties (heat-sealing layer) are laminated, the second substrate can be, for example, a film that does not have heat-sealing properties to which a heat-sealing agent containing a heat-sealing resin is applied.

[0025] Examples of heat-sealable resins include thermoplastic resins such as shellacs, rosins, rosin-modified maleic acid resins, rosin-modified phenolic resins, nitrated cotton, cellulose acetate, cellulose acetylpropionate, cellulose acetyl butyrate, chlorinated rubber, cycloadhesive 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. These can be used individually or in combination of two or more types.

[0026] The heat sealant may be in any form, such as a type in which these resins are dissolved in an organic solvent, a type in which they are dissolved in water or an aqueous organic solvent, or an emulsion type in which acrylic emulsions, urethane emulsions, polyvinyl alcohol resins, ethylene-vinyl alcohol emulsions, ethylene-methacrylic acid emulsions, polyolefin emulsions, ethylene vinyl acetate emulsions, etc., are dispersed in water or an aqueous organic solvent.

[0027] There are no particular restrictions on the organic solvents, but examples include aromatic hydrocarbons such as toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; and ester-based organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate.

[0028] Examples of aqueous organic solvents include alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, methyl ethyl ketone, and cycloxanone; 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.

[0029] Heat sealants may contain components other than heat-sealable resins and solvents. Examples of such components include waxes, fillers, defoamers, viscosity modifiers, leveling agents, tackifiers, preservatives, antibacterial agents, rust inhibitors, and antioxidants.

[0030] Known methods can be used for applying the heat sealant. For example, roll coaters, gravure coaters, flexo coaters, air doctor coaters, blade coaters, air knife coaters, squeeze coaters, impregnation coaters, transfer roll coaters, kiss coaters, curtain coaters, cast coaters, spray coaters, die coaters, offset printing presses, screen printing presses, etc. may be used. A drying process in an oven or the like may also be included after coating.

[0031] The thickness of the heat seal layer (amount of heat sealant applied (solid content)) can be arbitrary; for example, 0.5 g / m² 2 ~5g / m 2 That is the case.

[0032] The film thickness of the second substrate can be arbitrarily selected, but for example, when applied to the packaging material described later, it is selected in the range of 5 to 500 μm. It is more preferably 10 to 250 μm, and even more preferably 15 to 100 μm.

[0033] The second substrate may include a metal vapor-deposited layer such as aluminum, or an inorganic vapor-deposited layer such as aluminum oxide or silica.

[0034] (adhesive layer) The adhesive layer is a layer that bonds the first substrate and the second substrate via the first resin layer, which will be described later, and any optional layers provided as needed. The adhesive layer is, for example, (1) A two-component curing urethane adhesive comprising a polyol composition and a polyisocyanate composition (1) (2) A multi-component, solvent-free adhesive comprising an oil containing an acid anhydride group and a curing agent having a reactive group that can react with the acid anhydride group, wherein an adhesive layer is formed when these react and harden. (3) Adhesives mainly composed of olefin resins modified with acid and / or hydroxyl groups (3) (4) Polyurethane-based, polyolefin-based, polyethyleneimine-based, or epoxy resin-based anchor coating agents (4) It can be established by, but is not limited to, the following.

[0035] (Adhesive (1)) The polyol composition of adhesive (1) includes polyols such as polyester polyols, polyether polyols, vegetable oil polyols, polyurethane polyols, and sugar alcohols. Two or more of these polyols can also be used in combination.

[0036] Examples of polyester polyols include polyester polyols obtained as reaction products of polyhydric alcohols and polycarboxylic acids, and lactone-based polyester polyols obtained by polycondensation reactions of aliphatic polyols with various lactones such as ε-caprolactone. It is preferable to use polyester polyols obtained as reaction products of polyhydric alcohols and polycarboxylic acids.

[0037] 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)cyclohesane, and 2,2,4-trimethyl-1,3-pentanediol;

[0038] Trimethylolethane, trimethylolpropane, glycerin, hexanetriol, pentaerythritol, and other trifunctional or greater aliphatic polyols;

[0039] Examples include polyether polyols obtained by ring-opening polymerization of aliphatic diols or polyols with various cyclic ether-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 individually or in combination of two or more.

[0040] 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 anhydrides or ester-forming derivatives of these aliphatic or dicarboxylic acids; Examples include p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid and ester-forming derivatives of their dihydroxycarboxylic acids, and polybasic acids such as dimer acids, which can be used individually or in combination of two or more.

[0041] The molecular weight of the polyester polyol is not particularly limited, but as an example, it is between 250 g / mol and 20,000 g / mol. The hydroxyl value of polyester polyols is not particularly limited, but as an example, it is between 5 mg KOH / g and 500 mg KOH / g.

[0042] 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.

[0043] Polymerization initiators 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;

[0044] Trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol, and triol compounds of polypropylene glycol;

[0045] 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.

[0046] The molecular weight of the polyether polyol can be adjusted as appropriate, but one example is between 100 g / mol and 8000 g / mol. The hydroxyl value of polyether polyols can be adjusted as appropriate, but one example is between 10 mg KOH / g and 1200 mg KOH / g.

[0047] Examples of vegetable oil polyols include castor oil, dehydrated castor oil, hydrogenated castor oil (a hydrogenated form of castor oil), and castor oil alkylene oxide adducts of 5 to 50 moles.

[0048] Polyurethane polyols are reaction products of low-molecular-weight or high-molecular-weight polyols and polyisocyanate compounds. As the low-molecular-weight or high-molecular-weight polyol, the same polyhydric alcohols exemplified as raw materials for polyester polyols can be used. As the polyisocyanate compound, the same polyisocyanates that may be included in the isocyanate compositions described later can be used.

[0049] Examples of sugar alcohols include pentaerythritol, sucrose, xylitol, sorbitol, isomalt, lactitol, maltitol, and mannitol.

[0050] The polyisocyanate composition comprises a polyisocyanate compound having multiple isocyanate groups. The polyisocyanate compound is not particularly limited and includes aromatic diisocyanates, aromatic aliphatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and burettes, nurates, adducts, allophanates, carbodiimide modified forms, uretdione modified forms of these diisocyanates, and urethane prepolymers obtained by reacting these polyisocyanates with polyols. These can be used individually or in combination.

[0051] 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-phenylenediisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylenediisocyanate, 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.

[0052] Aromatic aliphatic diisocyanates refer to aliphatic isocyanates having one or more aromatic rings in their molecule, and include, but are not limited to, m- or p-xylylene diisocyanate (also known as XDI) and α,α,α',α'-tetramethylxylylene diisocyanate (also known as TMXDI).

[0053] Examples of aliphatic diisocyanates include 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, but are not limited to these.

[0054] Examples of alicyclic diisocyanates include, but are not limited to, 3-isocyanate-methyl-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(isocyanate-methyl)cyclohexane.

[0055] For the synthesis of urethane prepolymers, polyols similar to those exemplified as raw materials for polyester polyols above can be used alone or in combination of two or more. It is preferable to use at least one polyalkylene glycol or polyester polyol with a molecular weight of 200 to 3000 g / mol.

[0056] The adhesive (1) used in the present invention may be solvent-based or solvent-free. In this specification, a solvent-based adhesive refers to a form in which the polyol composition and polyisocyanate composition contain highly soluble organic solvents such as esters like ethyl acetate, butyl acetate, and cellosolve acetate, ketones like acetone, methyl ethyl ketone, isobutyl ketone, and cyclohexanone, ethers like tetrahydrofuran and dioxane, aromatic hydrocarbons like toluene and xylene, halogenated hydrocarbons like methylene chloride and ethylene chloride, dimethyl sulfoxide, and dimethyl sulfamide. A solvent-free adhesive refers to a form that substantially does not contain these organic solvents. If trace amounts of organic solvent remain in the polyol composition and polyisocyanate composition because the organic solvent used as a reaction medium during the production of the components of the polyol composition and polyisocyanate composition or their raw materials could not be completely removed, it is understood that the adhesive is substantially solvent-free. Furthermore, if 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, so it does not need to be volatilized after coating. Therefore, this form is also treated as a solvent-free adhesive, and the low molecular weight alcohol is not considered an organic solvent.

[0057] The adhesive (1) used in the present invention may contain components other than those described above, such as urethane catalysts, acid anhydrides, coupling agents, pigments, plasticizers, phosphoric acid derivatives, etc. These components may be included in either or both of the polyol composition and / or polyisocyanate composition, or they may be prepared separately and mixed with the polyol composition and / or polyisocyanate composition immediately before application of the adhesive (1).

[0058] Adhesive (1) is preferably used in a formulation such that the ratio [NCO] / [OH] of the number of moles of isocyanate groups [NCO] contained in the polyisocyanate composition (Y) to the number of moles of hydroxyl groups [OH] contained in the polyol composition (X) is 0.5 to 3.0.

[0059] In one embodiment of the present invention, the adhesive layer is a cured coating of such adhesive (1). The adhesive is applied to either the first substrate or the second substrate directly, or via the first resin layer or other optionally provided layer, and then bonded to the other substrate. After this bonding is performed, an aging treatment is carried out to form the adhesive layer. 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 / m². 2 More than 5g / m 2 The following applies:

[0060] (Adhesive (2)) The adhesive (2) containing acid anhydride oils and fats can be obtained, for example, by adding an acid anhydride-containing compound to an oil or fat. Preferably, an acid anhydride-containing oil or fat is one in which an acid anhydride is introduced into an oil or fat that contains a double bond derived from an unsaturated fatty acid in its chemical structure.

[0061] Fat containing double bonds derived from unsaturated fatty acids in its chemical structure is preferably a drying oil (iodine value > 130) and / or a semi-drying oil (iodine value 100-130). 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 oil (sardine oil, saury oil, herring oil, etc.). In addition, recycled vegetable oils recovered / recycled after being used for cooking, such as tempura oil, can also be used. Among these fats, tung oil, soybean oil, and linseed oil are preferably used due to their availability. Furthermore, fats of the grade known as refined oil or salad oil, which are refined so as not to crystallize for long periods even at low temperatures, are preferably used.

[0062] Compounds containing acid anhydrides that have double bonds in their molecules can be used for introducing acid anhydrides. Examples include maleic anhydride, citraconic anhydride, and tetrahydrophthalic anhydride. Among these, maleic anhydride is preferred due to its ease of introduction and the reactivity of its acid anhydride group.

[0063] The amount of acid anhydride group introduced into the oil or fat can be adjusted as appropriate, but taking the case of introducing maleic anhydride as an example, one example is 19 to 34 g (0.19 to 0.35 mol) of maleic anhydride per 100 g of oil or fat, and more preferably 22 to 29 g (0.22 to 0.30 mol).

[0064] Along with oils and fats containing acid anhydrides, various acids such as hydroxycarboxylic acids like citric acid, isocitric acid, malic acid, and tartaric acid, as well as phosphoric acid, monoalkyl phosphates, dialkyl phosphates, acetic acid, alkyl (C2-18) monocarboxylic acids, and dimer acids may be used in combination. These may be added when adding the acid anhydride to the oil or fat, or they may be added after the addition reaction is complete.

[0065] Examples of curing agents having reactive groups that can react with acid anhydride groups include nitrogen-containing compounds such as tertiary amine-containing polyols, amino alcohols, amide polyols, and polyamines, as well as compounds having hydroxyl groups. Tertiary amine-containing polyols are particularly preferred because the balance between their reactivity with oils and fats containing acid anhydride groups and the properties of the resulting film can be easily adjusted.

[0066] As a tertiary amine-containing polyol, it is particularly preferable to have 2 to 6 hydroxyl groups. It is also sufficient to have one or more tertiary amino groups, but it is preferable to have 1 to 2 tertiary amino groups. Specifically, examples include polypropylene glycol ethylenediamine ether, tri(1,2-polypropylene glycol)amine, N-ethyldiethanolamine, N-methyl-N-hydroxyethyl-N-hydroxyethoxyethylamine, pentakishydroxypropyldiethylenetriamine, and tetrakishydroxypropylethylenediamine.

[0067] Commercially available tertiary amine-containing polyols may be used. Examples include TE-360 (a tertiary amine-containing trifunctional polyol manufactured by Guodu Chemical Co., Ltd. (China)), TD-401 (a tertiary amine-containing tetrafunctional polyol manufactured by Guodu Chemical Co., Ltd. (China)), EDP-300, and EDP-450 (both tertiary amine-containing tetrafunctional polyols manufactured by Adeka Corporation).

[0068] Examples of amino alcohols that contain 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.

[0069] Examples of amide polyols include polyester amide polyols, which are obtained by using an aliphatic diamine having an amino group, such as ethylenediamine, propylenediamine, or hexamethylenediamine, as a raw material in the esterification reaction of the above polyester polyol.

[0070] There are no particular limitations on the polyamine; any known polyamine having primary and / or secondary amino groups can be used. The polyamine may also contain a tertiary amine.

[0071] More specifically, alkylenediamines such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, and hexamethylenediamine, and aliphatic diamines with 2 to 18 carbon atoms, represented by polyalkylenediamines such as diethylenetriamine, iminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0072] Alkyl (1-4 carbon atoms) or hydroxyalkyl (2-4 carbon atoms) substituted derivatives of aliphatic diamines such as dialkylaminopropylamines having 1-3 carbon atoms, trimethylhexamethylenediamine, aminoethylethanolamine, 2,5-dimethyl-2,5-hexamethylenediamine, and methyliminobispropylamine,

[0073] Alicyclic diamines with 4 to 15 carbon atoms, such as 1,3-diaminocyclohexane, isophoronediamine, mensendiamine, and 4,4'-methylenedicyclohexanediamine (hydrogenated methylenedianiline), and heterocyclic diamines with 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, are representative of alicyclic or heterocyclic-containing aliphatic diamines.

[0074] Aromatic ring-containing aliphatic amines with 8 to 15 carbon atoms, such as xylylenediamine and tetrachlorop-xylylenediamine.

[0075] Unsubstituted aromatic diamines with 6 to 20 carbon atoms, such as 1,2-, 1,3- or 1,4-phenylenediamine, 2,4'- and 4,4'-diphenylmethanediamine, crude diphenylmethanediamine (polyphenylpolymethylene polyamine), diaminodiphenylsulfone, benzidine, thiodianiline, 2,6-diaminopyridine, m-aminobenzylamine, triphenylmethane-4,4',4"-triamine and naphthylenediamine.

[0076] Aromatic diamines having 1 to 4 carbon atoms and a nuclear-substituted alkyl group, such as 2,4- or 2,6-tolylenediamine, crude tolylenediamine, diethyl tolylenediamine, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-bis(o-toluidine), dianisidine, diaminoditolylsulfone, 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 proportions.

[0077] Aromatic diamines having nuclear-substituted electron-withdrawing groups (halogen atoms such as fluorine, chlorine, bromine, and iodine; alkoxy groups such as methoxy and ethoxy groups; nitro groups, 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,

[0078] Aromatic diamines having a secondary amino group, such as 4,4'-di(methylamino)diphenylmethane and 1-methyl-2-methylamino-4-aminobenzene (in which part or all of the -NH2 of the above aromatic diamines is substituted with -NH-R' (where R' is an alkyl group; for example, a lower alkyl group such as a methyl group or an ethyl group)),

[0079] A low molecular weight polyamide polyamine is obtained by condensing a dicarboxylic acid such as a dimer acid with polyamines such as the above alkylenediamine and polyalkylene polyamine under conditions in which there is an excess of amino groups relative to the acid groups (2 moles or more of amino groups per mole of acid groups).

[0080] Examples include polyether polyamines, which are hydrides of cyanoethylated polyether polyols such as polyalkylene glycols.

[0081] Among these, polyamidoamines and polyether polyamines are preferred because they can form a coating with excellent strength.

[0082] Commercially available polyamines can also be used. Examples of such commercially available products include Jeffermin T-403, Jeffermin D-230, and Jeffermin D-400 (all polyether polyamines manufactured by Huntsman, USA).

[0083] In the case of polyether polyamines, they are preferably bifunctional or trifunctional, and those with a molecular weight of 200 to 5000, more preferably 200 to 1500, are preferably used.

[0084] Examples of compounds containing hydroxyl groups include, for example, compounds containing an average of two or more hydroxyl groups in the molecule, and 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, or mixtures thereof.

[0085] The polyester polyol can be the same as those exemplified as components of the polyol composition of adhesive (1), and those with a number average molecular weight of 400 to 2000 and a hydroxyl value of 60 to 300 are preferably used.

[0086] Polyether polyols and polyurethane polyols can be the same as those exemplified as components of the polyol composition of adhesive (1). Examples of polyether ester polyols include polyether ester polyols obtained by reacting the above-mentioned polyether polyol with dibasic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, and dimer acid, or their dialkyl esters, or mixtures thereof.

[0087] 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, etc.

[0088] Acrylic polyols can be obtained by copolymerizing hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, etc., which contain one or more hydroxyl groups per molecule, or their corresponding methacrylic acid derivatives, with, for example, acrylic acid, methacrylic acid, or their esters. Examples of polyhydroxyalkanes include butadiene, or liquid rubber obtained by copolymerizing butadiene with acrylamide or the like.

[0089] Examples of polyhydroxyalkanes include glycols (diols) such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol, as well as trivalent or tetravalent alcohols such as glycerin, trimethylolpropane, and pentaerythritol.

[0090] As for the compounds containing these hydroxyl groups, it is preferable to use at least one polyester polyol because the hydroxyl groups are highly reactive and can improve curability.

[0091] The curing agent preferably contains at least one nitrogen-containing compound. Only one nitrogen-containing compound may be used, or multiple compounds may be used in combination. The nitrogen-containing compound not only contributes to the formation of the cured adhesive, but if the curing agent contains a hydroxyl group-containing compound, the nitrogen contained in its structure acts as a catalyst to promote the reaction between the acid anhydride group and the hydroxyl group, thereby improving the curing rate.

[0092] In the oil containing acid anhydride groups and the curing agent, it is preferable that the molar ratio of acid anhydride groups in the oil to functional groups in the curing agent that can react with 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.

[0093] Furthermore, if the curing agent contains a nitrogen-containing compound, the amount of curing agent used should preferably result in a molar ratio (nitrogen / acid anhydride) of nitrogen in the nitrogen-containing compound to acid anhydride in the oil or fat of 0.5 to 0.8, more preferably 0.5 to 0.65.

[0094] Preferred combinations of oils containing acid anhydride groups and curing agents include: a combination of an oil containing maleic anhydride-modified tung oil and a curing agent containing a polyester polyol and a tertiary amine-containing polyol; a combination of an oil containing maleic anhydride-modified soybean oil and a curing agent containing a polyester polyol and a polyether polyamine; and a combination of an oil containing maleic anhydride-modified soybean oil and tung oil and a curing agent containing a polyester polyol, a polyether polyamine and a tertiary amine-containing polyol.

[0095] Adhesive (2) may use a polycarbodiimide compound as needed. The polycarbodiimide compound reacts with the carboxylic acid produced by the reaction of an acid anhydride-containing oil with a curing agent, forming a denser cured adhesive product and thereby improving the adhesive strength.

[0096] The polycarbodiimide compound can be any known polycarbodiimide compound without particular limitations. The molecular weight of the polycarbodiimide compound is preferably in the range of 1000 to 5000, and more preferably in the range of 2000 to 4000, when converted to a number-average molecular weight.

[0097] Carbodiimide compounds can also be obtained commercially, for example, Carbodilite V02B (solid content concentration 100%, carbodiimide equivalent 600), Carbodilite V05 (solid content concentration 100%, carbodiimide equivalent 262), Carbodilite V04PF (solid content concentration 100%, carbodiimide equivalent 336), and Carbodilite V05S (solid content concentration 90% by mass, carbodiimide group equivalent 291 (solid content equivalent 262)). Examples include Carbodilite V07 (solid content concentration 50% by mass, carbodiimide group equivalent 404 (solid content equivalent 202)), Carbodilite V09GB (solid content concentration 70% by mass, carbodiimide group equivalent 298 (solid content equivalent 209) (both manufactured by Nisshinbo Chemical Co., Ltd.)), with V02B and V05 being preferred. The carbodiimide-containing component may be contained alone, or two or more types may be contained.

[0098] When using polycarbodiimide compounds, it is preferable to use as little as possible, as their high viscosity may affect the coating properties.

[0099] Adhesive (2) may contain oils and fats containing the acid anhydride group described above, and components other than the curing agent. Examples of such components include, but are not limited to, catalysts, coupling agents, acid anhydrides, hydroxycarboxylic acids, oxygen scavengers, phosphoric acids, pigments, tackifiers, stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, nucleating agents, defoamers, leveling agents, etc. These components may be contained in only one of the first composition and the second composition described later, or in both.

[0100] 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 directly, or via the first resin layer or other optionally provided layer, and then bonded to the other substrate. After this bonding is performed, an aging treatment is carried out to form the adhesive layer. 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 / m². 2 More than 5g / m 2 The following applies:

[0101] (Adhesive (3)) Examples of olefin resins modified with acid and / or hydroxyl groups used in adhesive (3) include copolymers of olefin monomers and polymerizable monomers having acid groups (or acid anhydride groups) and / or hydroxyl groups, and resins obtained by graft-modifying olefin resins with polymerizable monomers having acid groups (or acid anhydride groups) and / or hydroxyl groups.

[0102] Examples of olefin resins having acid groups and / or acid anhydride groups include copolymers of olefin monomers with ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic acid anhydrides, and resins obtained by grafting polyolefins with ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic acid anhydrides.

[0103] Examples of olefin monomers include olefins with 2 to 8 carbon atoms, such as ethylene, propylene, isobutylene, 1-butene, 4-methyl-1-pentene, hexene, and vinylcyclohexane. Among these, olefins with 2 to 8 carbon atoms are preferred because they provide particularly good adhesive strength, and ethylene, propylene, and 1-butene are especially preferred.

[0104] Examples of ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic acid anhydrides used in copolymerization with olefin monomers include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, 4-methylcyclohexe-4-ene-1,2-dicarboxylic acid anhydride, bicyclo[2.2.2]octo-5-ene-2,3-dicarboxylic acid anhydride, and 1,2,3,4,5,8,9,10-octahydronaphthalene Examples include n-2,3-dicarboxylic acid anhydride, 2-octa-1,3-diketospiro[4.4]non-7-ene, bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride, maleopimaric acid, tetrahydrophthalic acid anhydride, methyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride, methyl-norbornene-5-ene-2,3-dicarboxylic acid anhydride, and norborn-5-ene-2,3-dicarboxylic acid anhydride. Among these, maleic anhydride is particularly preferred because of its excellent reactivity with olefin monomers, the reactivity of the acid anhydride after copolymerization, and the low molecular weight of the compound itself, which results in a high concentration of functional groups when copolymerized. These can be used alone or in combination of two or more.

[0105] In addition to olefin monomers, ethylenically unsaturated carboxylic acids, or ethylenically unsaturated carboxylic acid anhydrides, other compounds having ethylenically unsaturated groups, such as styrene, butadiene, and isoprene, may also be used in combination.

[0106] Polyolefins used when synthesizing acid-modified olefin resins by graft modification include homopolymers and copolymers of olefins having 2 to 8 carbon atoms, copolymers of olefins having 2 to 8 carbon atoms and other monomers. Specifically, examples include polyethylene such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene resin, polypropylene, polyisobutylene, poly(1-butene), poly(4-methyl-1-pentene), polyvinylcyclohexane, ethylene-propylene block copolymer, ethylene-propylene random copolymer, ethylene-1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-hexene copolymer, and other α-olefin copolymers, as well as ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-vinyl acetate-methyl methacrylate copolymer, propylene-1-butene copolymer, and ethylene-propylene-1-butene copolymer. 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 copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, and ethylene-propylene-1-butene copolymer are especially preferred.

[0107] As the ethylenically unsaturated carboxylic acid or ethylenically unsaturated carboxylic acid anhydride used for graft modification with polyolefins, those similar to those exemplified above can be used. Maleic anhydride is preferred because it exhibits high reactivity of the functional groups after graft modification and increases the concentration of functional groups in the graft-modified polyolefin. These can be used alone or in combination of two or more.

[0108] It is preferable to use an olefin resin having an acid group and / or anhydride group, having an acid value of 1 to 200 mg KOH / g.

[0109] Examples of olefin resins containing hydroxyl groups include copolymers of polyolefins with hydroxyl-containing (meth)acrylic acid esters or hydroxyl-containing vinyl ethers, and resins obtained by graft-modifying polyolefins with hydroxyl-containing (meth)acrylic acid esters or hydroxyl-containing vinyl ethers. The polyolefin used can be the same type used in the synthesis of olefin resins containing acid groups and / or acid anhydride groups.

[0110] 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 hydroxyl group-containing vinyl ethers include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether.

[0111] It is preferable to use an olefin resin having a hydroxyl value of 1 to 200 mg KOH / g.

[0112] The weight-average molecular weight of the olefin resin modified with acid and / or hydroxyl groups is preferably 40,000 or more, and preferably 250,000 or less.

[0113] The melting point of the olefin resin modified with acid and / or hydroxyl groups is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. The melting point of olefin resin (A) is preferably 120°C or lower, more preferably 90°C or lower, and even more preferably 85°C or lower.

[0114] Adhesive (3) is preferably used in combination with a curing agent. The curing agent is not particularly limited and can be any compound that can crosslink acid groups, acid anhydride groups and / or hydroxyl groups. Specifically, it is preferably at least one compound selected from the group consisting of isocyanate compounds, epoxy compounds, carbodiimide compounds, silane coupling agents, and metal compounds.

[0115] As the isocyanate compound, the same type as exemplified in adhesive (1) can be used. The isocyanate compound may be used alone or in combination of two or more types.

[0116] The epoxy compound is not particularly limited as long as it is a compound having an epoxy group in its molecule, for example, polyglycidyl ether type epoxy resins of aliphatic polyols such as ethylene glycol, propylene glycol, hexanediol, neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, glycerin, diglycerin, sorbitol, spiroglycol, or 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 phenol novolac resins and novolac-type epoxy resins, which are glycidyl eres of cresol novolac resins; Polyglycidyl ethers of polyols that 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; cyclic aliphatic type polyepoxy resins such as bis(3,4-epoxycyclohexylmethyl) adipate and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexyl carboxylate; Polyglycidyl ester type epoxy resins of polycarboxylic acids such as propanetricarboxylic acid, butanetetracarboxylic acid, adipic acid, phthalic acid, terephthalic acid, or trimellitic acid; Bis-epoxy 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, triglycidylparaaminophenol, tetraglycidylbisaminomethylcyclohexane, diglycidylaniline, and tetraglycidylmetaxylylenediamine; Examples include epoxy resins containing heterocyclic rings such as triazines and hydantoins. These epoxy resins may be used individually or in combination of two or more types.

[0117] Examples of carbodiimide compounds 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.

[0118] Examples of the silane coupling agent include aminosilanes such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane; epoxysilanes such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane; vinylsilanes such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane; and hexamethyldisilazane, γ-mercaptopropyltrimethoxysilane, etc.

[0119] The metal compound can be used without particular limitation as long as it can form an ionic crosslinking bond with an olefin resin modified with an acid and / or a hydroxyl group. Specifically, it is a compound containing metal ions, and examples thereof include metal oxides, hydroxides, carbonates, bicarbonates, acetates, formates, methoxides, ethoxides, etc. Examples of the metal ions include monovalent ions such as Li + 、Na + ; K + ; Ag + ; Cu + ; etc., and divalent ions such as Cu 2+ ; Ba 2+ ; Zn 2+ ; Fe 2+ ; etc. These metal ions can be mixed and contained in two or more kinds as needed.

[0120] Other compounds containing aziridine groups, oxazolines, amino resins, etc., can also be used. Examples of compounds containing aziridine groups 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.

[0121] 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'-(1,4-butylene)-bis(2-oxazoline), and 2,2'-(1,4-phenylene)-bis(2-oxazoline).

[0122] Examples of amino resins include melamine resin, benzoguanamine resin, and urea resin.

[0123] The amount of curing agent in 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 olefin resin modified with acid and / or hydroxyl groups. Furthermore, 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 olefin resin modified with acid and / or hydroxyl groups.

[0124] Adhesive (3) can achieve proper coating properties by further incorporating an organic solvent in addition to the above components, thereby ensuring fluidity. Such organic solvents are not particularly limited as long as they can be removed by volatilization during the drying process of adhesive application. 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; and ethanol, methanol, n-propanol, and 2-propanol (isopropyl alcohol). Examples of solvents include alcohol-based solvents such as butanol, hexanol, 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 individually or in combination of two or more.

[0125] It is preferable to use a mixed solvent of an alicyclic organic solvent and an ester solvent. In particular, when using an olefin resin having acid groups, acid anhydride groups and / or hydroxyl groups, it is preferable to use a mixed solvent of methylcyclohexane and ethyl acetate because of its excellent solubility.

[0126] The amount of organic solvent used is preferably such that the ratio of olefin resin to the total mass of olefin resin having acid anhydride groups and / or hydroxyl groups and the organic solvent is 10 to 30% by mass. This makes it possible to produce an adhesive with excellent coating properties and wettability to the substrate.

[0127] The adhesive (3) may contain various additives as needed, 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-based organic fine particles, defoamers, anti-sagging agents, wetting and dispersing agents, viscosity modifiers, UV absorbers, metal deactivators, peroxide decomposing agents, flame retardants, reinforcing agents, lubricants, rust inhibitors, fluorescent whitening agents, inorganic heat absorbers, flame retardants, antistatic agents, and dehydrating agents. The content of these additives should be adjusted as appropriate within a range that does not impair the function of the adhesive.

[0128] 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 directly, or via the first resin layer or other optionally provided layer, and after bonding with the other substrate, an aging treatment is performed to form the adhesive layer. For 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 for example, it is 1 g / m 2 More than 5g / m 2 The following applies:

[0129] (Anchor coating agent (4)) The adhesive layer may be formed by an anchor coating agent (4) used in a general extrusion lamination method. Examples of such anchor coating agents (4) include polyurethane-based, polyolefin-based, polyethyleneimine-based, or epoxy resin-based anchor coating agents. After applying the anchor coating agent (4) to the first substrate via a first resin layer or other optionally provided layers, 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.

[0130] The anchor coating agent (4) can be applied by coating methods such as the roll coating method, gravure roll coating method, and kiss coating method, or by printing methods. The thickness of the adhesive layer formed by the anchor coating agent (4) is, for example, 0.05 μm or more and 3.0 μm or less, preferably 0.1 μm or more and 2.0 μm or less, and more preferably 0.2 μm or more and 1.0 μm or less.

[0131] (First resin layer) The first resin layer is a layer placed between the first substrate and the adhesive layer, and comprises a first vinyl alcohol-based polymer and a first polyalkylene imine.

[0132] The first vinyl alcohol polymer is a hydrolysate of a vinyl ester homopolymer or copolymer, and can be obtained by known and conventional methods. Alternatively, the vinyl alcohol polymer is a reaction product of a hydrolysate of a vinyl ester homopolymer or copolymer and an aldehyde, and can be obtained by known and conventional methods.

[0133] 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 can be used individually or in combination of two or more. Vinyl acetate is preferred.

[0134] 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-dimethyl-4-vinyl-1,3-dioxolane, 3,4-dihydroxy-1-butene, 3,4-diasiloxy-1-butene, 3-asyloxy-4-hydroxy-1-butene, 4-asyloxy-3-hydroxy-1-butene, 3,4-diasiloxy-2-methyl-1-butene, 4,5-dihydroxy-1-pentene, 4,5-diasiloxy-1-pentene, and 4,5 Examples include 3,4-diacyloxy-1-butene such as -dihydroxy-3-methyl-1-pentene, 4,5-diasiloxy-3-methyl-1-pentene, 5,6-dihydroxy-1-hexene, and 5,6-diasiloxy-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, which can be used individually or in combination of two or more. In particular, 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.

[0135] When vinyl esters and polymerizable compounds are used in combination, their amounts can be adjusted as appropriate. For example, the amount of polymerizable compound used is 1 mol% to 40 mol% of the total amount of vinyl esters and polymerizable compounds. Another example is 1 mol% to 20 mol%, and yet another is 1 mol% to 15 mol%.

[0136] The first vinyl alcohol polymer may be acetalized. Aldehydes used for acetalization include aliphatic aldehydes such as formaldehyde, acetaldehyde, propylaldehyde, butyraldehyde, octylaldehyde, and dodecylaldehyde; alicyclic aldehydes such as cyclohexanecarbolaldehyde; aromatic aldehydes such as benzaldehyde, naphthaldehyde, anthraldehyde, phenylacetaldehyde, tolualdehyde, dimethylbenzaldehyde, cuminaldehyde, and benzylaldehyde; cyclohexenealdehyde, dimethylcyclohexenealdehyde, and hydroxyaldehyde. Examples include unsaturated aldehydes such as loreine; heterocyclic aldehydes such as furfural and 5-methylfurfural; hemiacetals such as glucose and glucosamine; and aldehydes having an amino group such as 4-aminobutyraldehyde. In addition, one or more types of 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.

[0137] Conventional known organic acids and inorganic acids such as acetic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, and hydrochloric acid can be used as acid catalysts during acetalization.

[0138] 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 more preferably 10,000 to 80,000.

[0139] In this invention, the first vinyl alcohol polymer used is one that is soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, and whose viscosity at 25°C is 200 mPa·s or less when a solution containing 5% by mass of the vinyl alcohol polymer is dissolved in a 1:1 (mass ratio) solution of water and ethanol is used. If no precipitate or gel-like substance is found after dissolving the vinyl alcohol polymer in a 1:1 (mass ratio) solution of water and ethanol and letting it stand at 25°C for one day, it is determined that the vinyl alcohol polymer has dissolved.

[0140] While vinyl alcohol polymers exhibit excellent solubility in water, many have poor solubility in low-molecular-weight alcohols such as ethanol, and such vinyl alcohol polymers dissolve only slightly in a cosolvent of water and ethanol. In this invention, a polymer with excellent solubility in a cosolvent of water and ethanol is selected and used. This makes it possible to make the coating agent used to form the first resin layer have excellent coating properties even with a high solid content, and to efficiently form a coating film of an appropriate thickness as the first resin layer. Furthermore, the energy required to volatilize the solvent from the coating agent during the formation of the first resin layer is reduced, thereby reducing the environmental burden. The solubility of vinyl alcohol polymers in low-molecular-weight alcohols can be adjusted, for example, by using ethylene or propylene together with vinyl esters to incorporate a skeleton that increases solubility in alcohol into the main chain, or by using 3,4-diacetoxy-1-butene together with vinyl esters to introduce hydroxyl groups into the side chains, as well as by adjusting the molecular weight, butyralization, and degree of saponification of the vinyl alcohol polymer. The degree of saponification of the vinyl alcohol polymer can be adjusted as appropriate, but as an example, it is 90% or more.

[0141] The first polyalkyleneimine is a resin having a polyalkyleneimine skeleton, and is obtained by polymerizing one or more alkyleneimines (e.g., ethyleneimine, propyleneimine) by conventional methods.

[0142] The first polyalkyleneimine may be a linear polyalkyleneimine consisting of linear polyalkyleneimine chains, or a branched polyalkyleneimine having branched polyalkyleneimine chains. Examples of polyalkyleneimines include polyethyleneimine and polypropyleneimine. The polyalkyleneimine may have substituents (e.g., hydroxypropyl group, hydroxyethyl group) introduced to at least some of the nitrogen atoms of the polyalkyleneimine chain. Polyalkyleneimines modified with organometallic compounds such as tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, polyhydroxytitanium stearate, titanium bisacetylacetonate, titanium tetraacetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium ethyl acetoacetate, titanium lactate, titanium triethanolamine, and titanium stearate may also be used, and two or more polyalkyleneimines may be used in combination.

[0143] The first polyalkyleneimine is thought to contribute to improving the adhesion between the vinyl alcohol polymer and the olefin film through its amino group (NHR group, NH2 group) and ethylene group, and since it is effective in improving adhesion, it is preferable that the polyalkyleneimine contains a branched polyalkyleneimine.

[0144] The number-average molecular weight of the first polyalkylene imine is, for example, between 5,000 and 100,000. The number-average molecular weight of the polyalkylene imine was measured by GPC (gel permeation chromatography) using pullulan as the standard substance.

[0145] From the viewpoint of balancing the adhesive strength of the laminate with suppression of blocking when winding after forming the first resin layer, it is preferable that the amount of the first polyalkylimine in the first resin layer is 1% by mass or more and 25% by mass or less of the total amount of the first vinyl alcohol polymer and the first polyalkylimine.

[0146] The first resin layer may contain resins other than the first vinyl alcohol polymer and the first polyalkylimine. Examples of such resins include cellulose resins, polyesters, polyurethanes, vinyl resins such as homopolymers or copolymers of olefins and styrenes, acrylic resins, epoxy resins, amide resins, natural rubber, and composites thereof (e.g., core-shell type resins). The content of these resins is preferably limited to 10% by mass or less of the total amount of the first vinyl alcohol polymer and the first polyalkyleneimine. More preferably, it is 5% by mass or less, and even more preferably 1% by mass or less. It may also be 0% by mass.

[0147] The first resin layer has a glass transition temperature of 40°C to 80°C. This prevents blocking when the substrate is wound up after the formation of the first resin layer, resulting in a laminate with excellent adhesive strength and recyclability. The glass transition temperature of the first resin layer can be adjusted by the first vinyl alcohol polymer, the first polyalkylene imine used, and their blending ratio. The glass transition temperature of the first resin layer is more preferably 50°C or higher, and more preferably 70°C or lower.

[0148] The first resin layer is formed, for example, by applying a coating agent containing a first vinyl alcohol-based polymer, a first polyalkylene imine, and an aqueous solvent onto a first substrate and drying the solvent.

[0149] As an aqueous solvent, water, water-soluble organic solvents that dissolve in water, etc., can be used. As water, pure water such as 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 hydrogen peroxide addition, as this can prevent the growth of mold or bacteria.

[0150] 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 cellosolve 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; and various other solvents known as aqueous organic solvents, such as sulfolanes, esters, ketones, lactones such as γ-butyrolactone, lactams such as N-(2-hydroxyethyl)pyrrolidone, glycerin, and its polyalkylene oxide adducts. These aqueous organic solvents can be used individually or in combination of two or more.

[0151] The coating agent used to form the first resin layer may further contain additives. Examples of additives include crosslinking agents, inorganic fillers, defoamers, leveling agents, stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, leveling agents, and the like.

[0152] Crosslinking agents include aldehydes such as formalin and glutaraldehyde; acetals such as glutaraldehyde diacetal; aliphatic polyisocyanates represented by hexamethylene diisocyanate and its derivatives (adduct, nurate, burette, etc.); aromatic aliphatic polyisocyanates represented by xylylene diisocyanate and its derivatives; aromatic polyisocyanates represented by toluene diisocyanate and its derivatives; isocyanates such as urethane prepolymers which are reaction products of these isocyanates with polyols; epoxys; titanium, silicon, aluminum, zirconium, Examples include organometallic compounds of boron and alkoxides; methylolureas such as methylolurea and methylolmelamine; 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. For isocyanates, blocked isocyanates using known blocking agents may be used, or emulsion-type isocyanates may be used.

[0153] The use of a crosslinking agent is expected to improve adhesion to olefin-based substrates. As an example, the amount of crosslinking agent is 5 to 50 parts by mass per 100 parts by mass of the total amount of the first vinyl alcohol polymer and the first polyalkyleneimine.

[0154] The resin content in the coating agent, including the first vinyl alcohol polymer and the first polyalkyleneimine, can be adjusted as appropriate, but as an example, it is 7.5% by mass or more. The solid content in the coating agent is not particularly limited, but is adjusted so that the viscosity at 25°C does not exceed 300 mPa·s.

[0155] The method of applying the coating agent is not particularly limited, and methods such as spraying, spin coating, dipping, roll coating, blade coating, doctor roll, doctor blade, curtain coating, slit coating, screen printing, inkjet, dispensing, die coating, direct gravure, reverse gravure, flexographic, knife coating, and dot coating can be used.

[0156] The thickness of the first resin layer can be adjusted as appropriate, but as an example, it is between 0.1 μm and 2.0 μm.

[0157] (Printing layer) The laminate of the present invention may include layers other than the first substrate, the second substrate, the adhesive layer, and the first resin layer. An example of such a layer is a printed layer. The printed layer is a layer on which characters, figures, symbols, or other desired patterns are printed using printing ink, either between the first substrate and the adhesive layer, or on the side of the first substrate opposite the adhesive layer. When the printed layer is placed between the first substrate and the adhesive layer, it is preferable that the printed layer be placed between the first resin layer and the adhesive layer. This allows for easy removal of the printed layer along with the adhesive, resulting in a higher purity recycled plastic, as described later.

[0158] The printing method and inks are not particularly limited, and known printing methods and inks can be used. The films used as the substrate often utilize printing inks produced by gravure printing, flexographic printing, lithographic offset printing, and inkjet recording printing methods. Printing inks that combine these methods with curing methods using active energy rays such as ultraviolet (UV), LED, or electron beam (EB), or by heat, are also used. Furthermore, depending on the solvent used, these may be referred to as water-based inks or organic solvent-based inks.

[0159] Specifically, these include gravure printing inks and flexographic printing inks (in some industries, gravure printing inks and flexographic printing inks are referred to as liquid inks), UV-curable inks for lithographic offset printing, electron beam-curable inks for lithographic offset printing, UV-curable inks for inkjet recording printing, and electron beam-curable inks for inkjet recording printing. Biomass inks made from biomass raw materials are also used as appropriate.

[0160] The printing ink may contain resin, colorant, and solvent as essential components, or it may be a so-called clear ink that contains resin and solvent but substantially no colorant. The printing layer may be provided over the entire surface of the first substrate or only on a portion of it.

[0161] 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 examples include 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 resin, epoxy resin, alkyd resin, rosin 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 resin are used.

[0162] Colorants used in printing inks include inorganic pigments such as titanium dioxide, 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.

[0163] The organic solvents used in printing inks preferably do not contain aromatic hydrocarbon organic solvents. More specifically, examples include alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. One or more of these can be used in combination.

[0164] In the liquid printing ink used in this invention, it is also preferable to use gravure printing ink or flexographic printing ink made from plant-derived raw materials, taking into consideration the construction of a sustainable circular society.

[0165] Examples of plant-derived raw materials include cellulose acetate propionate resin and nitrated cotton resins, polyamide resins using dimer acids or polymerized fatty acids derived from natural oils such as soybean oil, palm oil, and rice bran oil, as well as polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid, as well as polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer ol, and isosorbide, and polyisocyanates such as 1,5-pentamethylene diisocyanate and dimer isocyanate. Biomass polyurethanes synthesized from these plant-derived raw materials and rosin resins are also available.

[0166] For biomass gravure printing inks or flexographic printing inks, commercially available products listed by the Japan Organic Resources Association can also be used.

[0167] (Second resin layer) The laminate of the present invention may include, in addition to a first substrate, a second substrate, an adhesive layer, and a first resin layer, a second resin layer between the second substrate and the adhesive layer, comprising a second vinyl alcohol-based polymer and a second polyalkylene imine, and having a glass transition temperature of 40°C to 80°C. When a second resin layer is provided in addition to the first resin layer, the second resin layer and the second substrate can be easily separated in the desorption process described later, and the layers sandwiched between the first resin layer and the second resin layer, such as the printing layer and the adhesive layer, can be easily recovered after being separated from the first and second substrates without becoming too finely fragmented. In other words, it is preferable because it allows for a laminate with superior recyclability.

[0168] The second vinyl alcohol polymer can be the same as the one described as the first vinyl alcohol polymer (it can be dissolved in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, and the viscosity of the solution in which 5% by mass of the vinyl alcohol polymer is dissolved in a 1:1 (mass ratio) solution of water and ethanol at 25°C is 200 mPa·s or less). The second vinyl alcohol polymer may be the same as the first vinyl alcohol polymer, or it may be different. The second polyalkyleneimine can be the same as the one described for the first polyalkyleneimine. The second polyalkyleneimine may be the same as the first polyalkyleneimine, or it may be different.

[0169] The second resin layer can be formed in the same manner as the first resin layer. The coating agent used to form the second resin layer may be the same as the one used to form the first resin layer, or it may differ in, for example, the content of the second vinyl alcohol polymer and the second polyalkylene imine in the coating agent, the solvent used, and the amount of coating agent applied.

[0170] The glass transition temperature of the second resin layer is more preferably 50°C or higher, and more preferably 70°C or lower. In the second resin layer, the amount of the second polyalkylimine is preferably 1% by mass or more and 25% by mass or less of the total amount of the second vinyl alcohol polymer and the second polyalkylimine. The thickness of the second resin layer can be adjusted as appropriate, but one example is a thickness of 0.1 μm to 2.0 μm.

[0171] (Third substrate, third resin layer, fourth resin layer) The laminate of the present invention may include a third substrate in addition to the first substrate and the second substrate. The third substrate can be the same as the first substrate. In one embodiment of the present invention, the second substrate is a heat-sealable film (sealant film) that can melt and fuse with each other by heat, and the first substrate and the third substrate are substrates that are not expected to act as sealant films. In another embodiment of the present invention, the first substrate, the second substrate and the third substrate are all substrates that are not expected to act as sealant films.

[0172] If the laminate of the present invention includes a third substrate, the third substrate is placed between the first substrate and the second substrate, and the first substrate and the third substrate, and the third substrate and the second substrate are bonded together, either directly or via the first resin layer or other optionally provided layers, using adhesives similar to those described above. The adhesive layer placed between the first substrate and the third substrate and the adhesive layer placed between the third substrate and the second substrate may be formed from the same adhesive or from different adhesives.

[0173] On the surface of the third substrate facing the first substrate, a resin layer similar to the first resin layer (hereinafter also referred to as the third resin layer) may be provided between the third substrate and the adhesive layer. On the surface of the third substrate facing the second substrate, a resin layer similar to the first resin layer (hereinafter also referred to as the fourth resin layer) may be provided between the third substrate and the adhesive layer.

[0174] The third and fourth resin layers each contain a vinyl alcohol polymer (soluble at a concentration of 5% by mass or more in a 1:1 (mass ratio) solution of water and ethanol at 25°C, and the viscosity of a solution containing 5% by mass of the vinyl alcohol polymer in a 1:1 (mass ratio) solution of water and ethanol at 25°C is 200 mPa·s or less) and a polyalkylene imine, similar to the components exemplified as those of the first resin layer, and have a glass transition temperature of 40°C to 80°C.

[0175] When a third or fourth resin layer is provided in addition to the first and second resin layers, the first, second, and third substrates can be easily peeled off in the delamination process described later. Furthermore, the layers sandwiched between the first and third resin layers, such as the printing layer and the adhesive layer, and the layers sandwiched between the second and fourth resin layers, such as the adhesive layer, can be easily recovered after being peeled off from the substrate without becoming too finely fragmented. In other words, it is preferable because it allows for a laminate with superior recyclability.

[0176] The vinyl alcohol-based polymers used in the third and fourth resin layers may be the same as those used in the first and second vinyl alcohol-based polymers, respectively, or they may be different. The polyalkylene imines used in the third and fourth resin layers may be the same as those used in the first and second polyalkylene imines, respectively, or they may be different.

[0177] The third and fourth resin layers can be formed in the same manner as the first resin layer. The coating agent used to form the third and fourth resin layers may be the same as the one used to form the first resin layer, or it may differ in, for example, the content of the vinyl alcohol polymer and the second polyalkylene imine in the coating agent, the solvent used, and the amount of coating agent applied.

[0178] The glass transition temperatures of the third and fourth resin layers are more preferably 50°C or higher, and more preferably 70°C or lower. In the third and fourth resin layers, the amount of polyalkylimine 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. The film thicknesses of the third and fourth resin layers can be adjusted as appropriate, but as an example, they are between 0.1 μm and 2.0 μm.

[0179] (Barrier coat layer) The laminate of the present invention may include layers other than those described above. An example of such a layer is a barrier coat layer. The barrier coat layer is a layer that prevents the permeation of oxygen and water vapor, and can be provided at any position in the laminate of the present invention by applying and drying a barrier coat agent.

[0180] Examples of barrier coating agents include a barrier coating agent (1) containing a vinyl alcohol-based polymer and an aqueous solvent.

[0181] Specific examples of vinyl alcohol polymers include polyvinyl alcohol, ethylene vinyl alcohol, and polyvinyl butyral. Vinyl alcohol polymers may also have reactive functional groups other than hydroxyl groups, such as acetoacetyl groups, carboxyl groups, anionic carboxyl groups, sulfonic acid groups, and anionic sulfonic acid groups. These may be used individually or in combination of two or more.

[0182] As the aqueous solvent, water or the same water-soluble organic solvents exemplified for use in preparing the coating agent used to form the first resin layer can be used. The aqueous solvent can be used alone or in combination of two or more types.

[0183] The barrier coating agent (1) may further contain additives such as a layered inorganic compound, a crosslinking agent that reacts with the functional groups of the vinyl alcohol polymer, an adhesion enhancer, an inorganic filler, an antifoaming agent, a stabilizer (antioxidant, heat stabilizer, UV absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, and a leveling agent.

[0184] Commercially available barrier coating agents (1) can also be used, including, for example, Exevia (registered trademark) from Sumitomo Chemical, the SunBar (registered trademark) series from Sun Chemical, the Takelac WPB (registered trademark) series from Mitsui Chemicals, and LG-OX from Tokyo Ink Co., Ltd.

[0185] The barrier coating agent consists of a water-soluble polymer having a hydroxyl group and Si(OR 1 )4, or R 2 Si(OR 3 )3(However OR 1 and OR 3 represents a hydrolyzable group, R 2 Examples of gas barrier coating agents (2) include one or more silicon compounds represented by (where represents an organic functional group), or hydrolyzed products of said silicon compounds.

[0186] Examples of water-soluble polymers containing hydroxyl groups include vinyl alcohol polymers, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, and sodium alginate.

[0187] Examples of silicon compounds or hydrolysates of said silicon compounds include tetraethyl silicate (Si(OC2H5)4) (hereinafter sometimes referred to as TEOS), tetraalkoxysilanes such as tetramethyl silicate; trialkoxysilanes such as trimethoxymethylsilane, triethoxymethylsilane, and trimethoxyvinylsilane; dialkoxysilanes such as dimethoxydimethylsilane and diethoxydimethylsilane; monoalkoxysilanes such as methoxytrimethylsilane and ethoxytrimethylsilane, or their hydrolysates or partial hydrolysates.

[0188] TEOS is preferred because it is relatively stable in aqueous solvents after hydrolysis. 2 Si(OR 3 )3 contains R 2 The group is preferably a vinyl group, epoxy group, acryloyl group, methacryloxy group, ureido group, or isocyanate group.

[0189] The barrier coating agent (2) may contain components other than those mentioned above. Examples of such components include other water-soluble polymers (e.g., sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethylcellulose, etc.), fragrances, rust inhibitors, colorants, fillers, defoamers, UV absorbers, fluorescent whitening agents, liquid paraffins, bitter components (e.g., denatonium benzoate, etc.). Furthermore, the barrier coating agent (2) can use the same aqueous solvent as the gas barrier coating agent (1).

[0190] Examples of barrier coating agents include a polyester polyol, which is a reaction product of an acid component containing an ortho-directing polycarboxylic acid or a meta-directing polycarboxylic acid and a polyol component, and an isocyanate compound (3).

[0191] Examples of ortho-directing polycarboxylic acids include orthophthalic acid or its acid anhydride, naphthalene 2,3-dicarboxylic acid or its acid anhydride, naphthalene 1,2-dicarboxylic acid or its acid anhydride, anthraquinone 2,3-dicarboxylic acid or its acid anhydride, and 2,3-anthracenecarboxylic acid or its acid anhydride. These compounds may have substituents on any carbon atom of the aromatic ring. Examples of substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, or naphthyl group.

[0192] Examples of meta-directing polycarboxylic acids include isophthalic acid and 1,3-naphthalenedicarboxylic acid. These compounds may have substituents on any carbon atom of the aromatic ring, similar to those exemplified in the description of ortho-directing polycarboxylic acids.

[0193] The polycarboxylic acids used in the synthesis of polyester polyols may include polycarboxylic acids other than ortho-directing or meta-directing polycarboxylic acids. These polycarboxylic acids 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 include aromatic polycarboxylic acids such as spiral dicarboxylic acid, 2,6-anthracenedicarboxylic acid, 2,7-anthracenedicarboxylic acid, 1,8-anthracenedicarboxylic acid, 9,10-anthracenedicarboxylic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid and acid anhydrides or ester-forming derivatives of these dicarboxylic acids, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid and ester-forming derivatives of these dihydroxycarboxylic acids, and one or more of these can be used in combination. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, and its acid anhydride are preferred.

[0194] When the polycarboxylic acid includes polycarboxylic acids other than ortho-directing polycarboxylic acids or meta-directing polycarboxylic acids, it is preferable that the proportion of ortho-directing polycarboxylic acids or meta-directing polycarboxylic acids to the total amount of polycarboxylic acids is 40 to 100% by mass.

[0195] The polyhydric alcohols used in the synthesis of polyester polyols preferably include dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, and cyclohexanedimethanol, as well as trihydric alcohols such as glycerol, trimethylolethane, and trimethylolpropane. Among these, the inclusion of ethylene glycol and glycerol is more preferable. The inclusion of glycerol is particularly preferable. Glycerol is preferably present in an amount of 10% to 100% by mass in the polyhydric alcohol.

[0196] Polyhydric alcohols other than those listed above may be used in combination. Examples 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 dipentaerythulitol; hydroquinone, resorcinol, catechol, naphthalenediol, biphenol, bisphenol A, hisphenol F, tetramethylbiphenol, and aromatic polyhydric phenols such as ethylene oxide extensions thereof and hydrogenated alicyclic groups.

[0197] If 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. Preferably, the proportion of hydroxyl groups modified with a polycarboxylic acid is 1 / 3 or less of the total hydroxyl groups present in 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.

[0198] The polyester polyol may also be a polyester polyurethane polyol with a number average molecular weight of 1,000 to 15,000, obtained by urethane elongation through reaction with a diisocyanate compound. Since the urethane-elongated polyester polyol contains molecular weight components above a certain level and urethane bonds, it has excellent gas barrier properties and superior initial cohesive strength.

[0199] The isocyanate compound used in the barrier coating agent (3) can be the same as the polyisocyanate compound used in the adhesive (1). It is preferable to use one that has an aromatic ring or an aliphatic ring. Examples of isocyanate compounds having aromatic or aliphatic rings include toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, or 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, metaxylylene alcohol, 1,3-bishydroxyethylbenzene, 1,4-bishydroxyethylbenzene, trimethylolpropane, glycerol, pentaerythritol, erythritol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, metaxylylenediamine and their alkylene oxide adducts, various polyester resins, polyether polyols, and high molecular weight active hydrogen compounds of polyamides. The isocyanate compounds may be used alone or in combination of multiple types of isocyanate compounds.

[0200] The barrier coating agent (3) may also preferably contain a compound having an active hydrogen group. Examples of active hydrogen groups in compounds containing active hydrogen include hydroxyl groups, amino groups, imino groups, carboxylic acids, urea groups, or SH groups. Among these, hydroxyl groups, amino groups, or SH groups are preferred.

[0201] When the solubility parameter of the compound containing active hydrogen is 29.5 or less, the compatibility between the polyester polyol and the isocyanate compound is improved, the compound containing active hydrogen is uniformly distributed in the barrier coat layer, and an improvement in gas barrier properties can be expected. In this specification, the solubility parameter shall be the δT value included in the Hansen Solubility Parameter Calculation Software (HSPiP) or the δT value calculated using the SMILES notation.

[0202] 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 include dihydric alcohols such as dimethyl-1-octen-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, isitol, dalcitol, althritol, inositol, and dipentaerythritol; and heptahydric alcohols such as perseitol.

[0203] Compounds having an amino group as an active hydrogen group include, for example, 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.

[0204] 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. Examples include 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, trimethylolpropanetris(3-mercaptobutyrate), pentaerythritoltetrakis(3-mercaptobutyrate), etc.

[0205] Compounds containing active hydrogen may be used individually or in combination of multiple types. Isosorbide, tris(2-hydroxyethyl) isocyanurate, trimethylolpropane, dipentaerythritol, and 1,4-cyclohexanedimethanol are preferred.

[0206] The amount of the compound containing active hydrogen is preferably 0.5% by mass or more and 20% by mass or less relative to the solid content of the barrier coating agent (3).

[0207] The barrier coating agent (3) may further contain layered inorganic compounds, acid anhydrides, oxygen scavengers, inorganic fillers, dispersants (if inorganic materials are used), stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, leveling agents, slip enhancers, etc.

[0208] The barrier coating agent (3) may be diluted with an organic solvent. Examples of organic solvents include ester solvents such as ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone and 2-butanone; ether solvents such as tetrahydrofuran; aliphatic solvents such as hexane and cyclohexane; and aromatic solvents such as toluene.

[0209] (Heat-resistant coating layer) The laminate of the present invention may include layers other than those described above. An example of such a layer is a heat-resistant coating layer. The heat-resistant coating layer is a layer that has the 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.

[0210] To illustrate with an example where the laminate of the present invention is used as a component for packaging materials to wrap contents, if the outermost base material when the bag is formed and filled with contents is a film with low heat resistance, such as a polyethylene film or a polypropylene film, there is a risk that the laminate may shrink due to heat when forming the bag by heat sealing. Such problems can be suppressed by providing a heat-resistant coating layer.

[0211] The heat-resistant coating layer is preferably positioned outside the outermost substrate among the substrates constituting the laminate, as viewed from the contents when the bag is made. For example, if the first substrate is the outermost substrate among the substrates constituting the laminate of the present invention, and the printing layer is provided between the first substrate and the adhesive layer, the heat-resistant coating layer is preferably provided on the side of the first substrate opposite to the adhesive layer. Alternatively, if the first substrate is the outermost substrate among the substrates constituting the laminate of the present invention, and the printing layer is provided on the side of the first substrate opposite to the adhesive layer, the heat-resistant coating layer may be positioned between the printing layer and the first substrate, or the printing layer may be positioned between the heat-resistant coating layer and the first substrate.

[0212] Examples of heat-resistant coating agents include coating agents containing compounds having a cellulose skeleton, benzene ring skeleton, isocyanuryl ring skeleton, or alicyclic skeleton, the glass transition temperature (hereinafter sometimes referred to as Tg) of the homopolymer being 100°C or higher. Specific examples of such compounds include cellulose derivatives such as nitrated cotton, cellulose acetate, cellulose propionate, and cellulose butyrate; polyester resins having a benzene ring such as phthalic acid, naphthalenedicarboxylic acid, and ethylene oxide (hereinafter sometimes referred to as EO) adduct of bisphenol A, and / or alicyclic skeletons such as cyclopentanediol and dimethylol tricyclodecane; or urethane resins bonded with aromatic isocyanates such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, and naphthalenediisocyanate; alicyclic isocyanates such as isophorone diisocyanate and norbornene diisocyanate; and / or isocyanuryl triisocyanate with polyols and / or tris(2-hydroxyethyl) isocyanurate. Furthermore, polyisocyanates using the aforementioned isocyanates may 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 can also be preferably used. In addition, resins with a low Tg may be mixed in to improve adhesion to olefin films.

[0213] For heat-resistant coatings, it is preferable to use inorganic fine particles such as alumina, magnesia, titania, zirconia, and silica (quartz, fumed silica, precipitated silica, anhydrous silicic acid, fused silica, crystalline silica, ultrafine amorphous silica, etc.) as aggregates because they have excellent heat resistance. Alternatively, boron nitride, aluminum nitride, aluminum oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, etc. are preferred because they have excellent thermal conductivity. Inorganic fine particles may be used individually or in combination of multiple types.

[0214] The shape of the silica nanoparticles is not particularly limited; spherical, hollow, porous, rod-shaped, plate-shaped, fibrous, or irregularly shaped nanoparticles can be used. For example, commercially available hollow silica nanoparticles include Silinax manufactured by Nippon Steel Mining Co., Ltd.

[0215] The primary particle size of the inorganic fine particles is preferably in the range of 5 nm to 200 nm, and more preferably in the range of 10 nm to 100 nm. Inorganic fine particles can be blended in a ratio of 5 to 90% by weight relative to the total solid content of the heat-resistant coating agent and the inorganic fine particles, and the blending amount can be adjusted as needed depending on the purpose. In particular, a ratio of 20% by weight or more is preferred.

[0216] The heat-resistant coating agent may be colored. There are no particular limitations on the coloring agent, and examples include inorganic pigments, organic pigments, and dyes used in general inks, paints, and recording materials, such as those used in the printing layer described later.

[0217] Heat-resistant coatings can use waxes, silicone additives, and organic beads. Specifically, waxes such as amide wax, polypropylene wax, polyethylene wax, paraffin wax, carnauba wax, and rice wax, ethylene oxide (EO) adducts of dimethylsiloxane, silicone additives of silicone-modified materials, and organic beads made of acrylic, nylon, urethane, or epoxy can be added.

[0218] There are no particular restrictions on the solvent used in the heat-resistant coating agent, but examples include aromatic hydrocarbon organic solvents such as water, toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, and decane; and various ester-based organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate. Furthermore, examples of water-miscible organic solvents include alcohol-based solvents such as methanol, ethanol, propanol, butanol, and isopropyl alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, and cycloxanone; and glycol ether-based solvents 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. These can be used individually or in combination of two or more. In addition, defoamers and leveling agents may be used to more effectively carry out the coating.

[0219] Heat-resistant coating agents can also be commercially available. Examples include SUNSYS FS241 from Sun Chemical Co., Ltd., DH-004 / DH-HARDENER P-60 from DIC Corporation, and ThermaGloss463 from Michaelman Corporation.

[0220] <Packaging material> The laminate of the present invention can be used as a multilayer packaging material for the purpose of protecting food, pharmaceuticals, and other products. When used as a multilayer packaging material, the layer configuration may change depending on the contents, usage environment, and usage method.

[0221] The packaging material of the present invention can be obtained, for example, by overlapping the heat-seal layers of the laminate of the present invention opposite each other and then heat-sealing the peripheral edges. Methods for making the bag include folding or overlapping the laminate of the present invention so that the inner layer surfaces (sealant film surfaces) face each other, and then heat-sealing the peripheral edges in forms such as side seal type, two-side seal type, three-side seal type, four-side seal type, envelope-type seal, gusset-type seal, pleated seal type, flat-bottom seal type, square-bottom seal type, gusset type, and other heat-seal types. The packaging material of the present invention can take various forms depending on the contents, usage environment, and usage. Self-standing packaging materials (standing pouches) are also possible. Heat sealing can be performed using known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high-frequency sealing, and ultrasonic sealing.

[0222] Products using the packaging material of the present invention are manufactured by filling the packaging material with contents through its opening and then heat-sealing the opening. The contents that can be filled include confectionery such as rice crackers, bean snacks, nuts, biscuits / cookies, wafers, marshmallows, pies, semi-fresh cakes, candies, and snack foods; staples such as bread, instant noodles, dried noodles, pasta, aseptically packaged rice, porridge, rice gruel, packaged mochi, and cereal foods; processed agricultural products such as pickles, boiled beans, natto, miso, frozen tofu, tofu, enoki mushrooms, konjac, processed wild vegetables, jams, peanut cream, salads, frozen vegetables, and processed potato products; processed livestock products such as ham, bacon, sausages, processed chicken products, and corned beef; and fish ham and sausages. Examples of products that can be packaged using this material include processed seafood products such as fish paste products, kamaboko (fish cake), nori (seaweed), tsukudani (simmered seafood), katsuobushi (dried bonito flakes), shiokara (salted seafood), smoked salmon, and spicy mentaiko (spicy cod roe); fruit pulp such as peaches, oranges, pineapples, apples, pears, and cherries; vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes; frozen and chilled prepared foods such as hamburgers, 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. Furthermore, the packaging material of the present invention can also be used as a packaging material for cigarettes, disposable hand warmers, pharmaceuticals such as intravenous fluid packs, cosmetics, and vacuum insulation materials.

[0223] <Recycling Methods> The laminates and packaging materials made from the laminates of the present invention have excellent recyclability and can be used as raw materials for recycled plastics. The recycled plastics of the present invention are recycled using the laminates and packaging materials of the present invention as raw materials. For example, the recycled plastics of the present invention can be obtained by peeling the laminates and packaging materials of the present invention into their respective base materials (peeling step), separating them by resin type (separation and collection step), melting and kneading each, and then pelletizing them.

[0224] (Peeling process) The laminates and packaging materials of the present invention can be separated into single-layer films by immersing them in a release agent for a certain period of time, which allows the adhesive and printing ink to peel off from the substrate. The laminates and packaging materials of the present invention can be easily peeled off with hot water at 55°C or higher, so hot water may be used as the release agent. However, in addition to water, a release agent containing various surfactants such as basic compounds, hydrophilic alcohols, anionic surfactants, nonionic surfactants, silicone-based surfactants, fluorine-based surfactants, and biosurfactants, as well as other additives, may also be used.

[0225] When using a film having a metal or metal oxide vapor-deposited layer as a base material, using a release agent containing a basic compound is preferable because it dissolves these layers, making it easier to peel off the laminate, and also reduces the impact on the physical properties of the recycled pellets. Furthermore, even when using such a substrate, if any of the first to fourth resin layers described above are formed in contact with the vapor-deposited layer, the vapor-deposited layer can be removed from the film even when using hot water at 55°C or higher as a release agent.

[0226] As for the water, pure water such as tap water, deionized water, ultrafiltered water, reverse osmosis water, or 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 hydrogen peroxide addition, as this can prevent the growth of mold or bacteria. When using a release agent containing a basic compound, it is preferable to use water with a hardness of 120 ppm or less, and more preferable to use water with a hardness of 80 ppm or less.

[0227] 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 approximately 10 to 14.

[0228] Hydrophilic alcohols are aliphatic alcohols that can be mixed with water in any proportion. Examples of hydrophilic alcohols include methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, and glycerin. These can be used individually or in combination of two or more, with ethanol being preferred. When the stripping agent contains a hydrophilic alcohol, its content is preferably 1% by mass or more and less than 60% by mass of the stripping agent.

[0229] The immersion time in the release agent is not particularly limited, but as an example, it is between 10 minutes and less than 5 hours. The immersion process in the release agent may be performed only once or multiple times. If the immersion process is performed multiple times, the release agent used may be the same or different.

[0230] The peeling of the laminate and packaging material is preferably carried out by heating to 55°C to 85°C, and more preferably by heating to 70°C to 85°C. There are no particular limitations on the heating method, and known heating methods such as heat rays, infrared rays, and microwaves can be used. It is preferable that the treatment tank used for immersion in the release agent is heated and equipped with a reflux condenser for refluxing the evaporated release agent.

[0231] When immersing the laminated film in the release agent, it is preferable that the release agent is agitated. Methods of agitation include, for example, mechanical agitation of the laminated film dispersion in the treatment tank using agitator blades, agitation using a water pump, and bubbling with an inert gas such as nitrogen gas. Several methods may be used in combination. This allows for more efficient separation of the laminated film.

[0232] During immersion in the stripping agent, ultrasonic vibrations may be applied to the stripping solution. One method of applying ultrasonic vibrations is to attach an ultrasonic transducer to the treatment tank.

[0233] (Separation and collection process) The release agent after the release process contains adhesives and printing inks that have been removed from the laminate, film fragments (first substrate, second substrate, etc.) that have separated from the laminate due to the removal of the adhesive, and (if the laminate contained a metal layer or metal vapor-deposited layer) metal fragments that are floating or dissolved in the release agent. In the sorting and recovery process, these are removed from the release agent, sorted, and recovered.

[0234] One specific method involves separating lighter plastics such as polypropylene and polyethylene (polyolefins) from heavier materials such as polyester, nylon, condensation-based films, or metal foils by flotation separation, and then removing the heavier materials. Next, the recovered plastics are washed and dewatered, and then separated by centrifugal separation to separate plastics with different specific gravities. For example, this can be used to separate plastic separation materials containing polyvinyl chloride resin or polyethylene terephthalate, which have a specific gravity of 1 or more and sink in water, from plastic separation materials containing olefin resins such as polyethylene and polypropylene, which do not contain polyvinyl chloride resin. By appropriately changing the mixing ratio of the liquids used for separation, such as water and organic solvents, film pieces with various specific gravities can be separated and recovered.

[0235] (Reuse of release agent) The release agent used in the laminate delamination process is preferably recovered and reused after removing components other than film fragments, such as adhesive layer fragments and printed layer fragments that have been peeled off the laminate. One method for removing components other than film fragments is filtration.

[0236] Components such as adhesive and printed layer fragments can be further broken down by shear forces applied during the peeling process, often through stirring. If the adhesive and printed layer fragments are broken down too much during the peeling process, they may not be completely filtered out depending on the filter's aperture diameter, and these fragments may remain in the peeling agent after filtration, causing the peeling agent to become discolored. Using a filter with a smaller aperture diameter to suppress discoloration of the peeling agent after filtration will require a longer filtration time.

[0237] In the laminate of the present invention, particularly when a first resin layer and a second resin layer are provided and layers such as a printed layer and an adhesive layer are sandwiched between them (for example, a first substrate / first resin layer / either or both of the printed layer and the adhesive layer / second resin layer / second substrate), or when a film having a metal or metal oxide vapor-deposited layer is used as the second substrate, and a printed layer and an adhesive layer are sandwiched between the first resin layer and the vapor-deposited layer provided on the second substrate (for example, a first substrate / first resin layer / either or both of the printed layer and the adhesive layer / second substrate having a metal or metal vapor-deposited layer), after the printed layer and adhesive layer are peeled off from the first and second substrates, the printed layer fragments and adhesive layer fragments can be recovered even with a filter that has a relatively large aperture diameter without becoming too finely fragmented, and the release agent can be filtered efficiently. The same applies when the laminate of the present invention includes a third substrate.

[0238] The aperture diameter of the filter is adjusted appropriately considering the filtration efficiency of the release agent and the degree of discoloration of the release agent after filtration, and is typically between 10 μm and 200 μm. As described above, when a printing layer or adhesive layer is placed between two resin layers (for example, the first resin layer and the second resin layer, the first resin layer and the third resin layer, or the second resin layer and the fourth resin layer), or when a printing layer or adhesive layer is placed between a resin layer (any of the first to fourth resin layers) and a metal or metal oxide vapor deposition layer, the aperture diameter of the filter used for filtering the release agent can be, for example, 30 μm to 200 μm, for another example, 50 μm to 200 μm, or for yet another example, 100 μm to 200 μm.

[0239] (Pelletization) The film fragments recovered by resin type in the sorting and recovery process are heated and melted at 120-280°C and then kneaded. The melting temperature can be adjusted considering the glass transition temperature and melting temperature of the resin, the shape during pelletization, and the pressure applied during the molding process. The screw rotation speed during kneading is, for example, 50-1000 RPM.

[0240] The melt-mixed film pieces are cooled and shredded to form recycled plastic pellets. Examples of pelletizing methods include hot-cutting and strand-cutting, but are not particularly limited. To prevent foreign matter from being mixed into the pellets, it is preferable to provide a screen mesh at the discharge section of the melt-mixed laminate and packaging material. Examples of screen meshes include woven types such as plain weave, twill weave, plain tatami weave, and twill tatami, as well as perforated metal types. The size of the screen mesh is preferably 40 mesh or more, more preferably 80 mesh or more, and even more preferably 120 mesh or more, taking into account the pressure at the discharge section and clogging. Examples of cooling methods include air cooling, wind cooling, and water cooling. In this invention, it is preferable to include a water cooling step. Cooling to 20°C to 80°C is preferable, and cooling to 30°C to 60°C is more preferable.

[0241] The recycled plastic of the present invention may contain known additives. Examples of such additives include at least one antioxidant selected from the group consisting of phenolic and phosphorus-based agents; at least one lubricant selected from the group consisting of fatty acid amides, alkylene fatty acid amides, metal soaps, and esters; a hindered amine-based weather stabilizer; a wax with an acid value of 5 mg KOH / g or less; and at least one antistatic agent selected from the group consisting of fatty acid sulfons and fatty acid esters.

[0242] 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 added is of the same resin type as the film piece. The virgin plastic may be added when pelletizing the film piece, or when molding the pelletized recycled plastic of the present invention. It may also be added both when pelletizing and when molding the recycled plastic. As an example, the amount of virgin plastic used in combination when pelletizing the film piece is in the range of film piece:virgin plastic 100:0 to 25:75 (mass ratio). As an example, the amount of virgin plastic used when molding the pelletized recycled plastic of the present invention is in the range of recycled plastic:virgin plastic 100:0 to 25:75 (mass ratio).

[0243] (Crushing process) Prior to the step of immersing the laminate in a release agent, a step of crushing the laminate may be provided. This increases the surface area of ​​the laminate that comes into contact with the release agent, thereby shortening the peeling time of the laminate. On the other hand, the separated laminate can then be separated by specific gravity sorting or the like, but in this case, 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 about 5 to 60 mm. The crushing method may be so-called wet crushing, which is performed in water or a washing solution, or dry crushing, which is performed in an air atmosphere where no liquid such as a solvent is present.

[0244] While there are no particular limitations on the type of wet crusher, a wet crusher capable of simultaneously crushing, dispersing, mixing, and pumping solid material in a liquid is preferred. Specifically, a crusher having a mechanism for crushing solid material in a liquid using shear force and / or frictional force is preferred, as is a crusher having a mechanism for crushing and pumping plastic film. Examples of such wet crushers include wet crushing pumps, colloid mills, and grinders.

[0245] Dry crushers are not particularly limited, but examples include mycoloiders, mascoloiders, ball mills, power mills, pin mills, air-jet mills, shear friction mills, cutter mills, impact mills (hammer mills, ball mills), roll mills, homogenizers, ultrasonic crushers, etc.

[0246] (Washing process) It is preferable that the crushed laminate pieces undergo a washing process before being sent to the peeling process. In the washing process, the pieces are placed in a washing container containing a washing solution such as water or a detergent solution, and stirred in the washing container to wash away organic matter (food residue, grease, etc.) and inorganic matter (sand, dust, etc.) adhering to the laminate. Next, the laminate pieces are transferred to a rinsing container containing rinsing water, rinsed, and then drained.

[0247] 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, shipping pallets and containers, bottles and other containers, hangers, stationery, pots and cups, disposable cutlery, and toys. It can also be recycled as film, or the recycled film can be molded and used as cushioning material when transporting fruits, for example, but is not limited to these uses. [Examples]

[0248] The present invention will be described in more detail below with reference to specific synthesis examples and embodiments, but the present invention is not limited to these embodiments. In the following examples, "parts" and "%" represent "parts by mass" and "mass%", respectively, unless otherwise specified.

[0249] <Preparation of coating agent> (Preparation of coating agent) Coating agents were prepared according to the formulations shown in Tables 1 and 2. The compounds used in the preparation of the coating agents are as follows: Polyvinyl alcohols 1 and 2 are soluble at a concentration of 5% by mass or more in a 1:1 (mass ratio) solution of water and ethanol at 25°C, and the viscosity of 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 is 200 mPa·s or less at 25°C. Polyvinyl alcohols 3, 4, and 5 precipitate without dissolving at a concentration of 5% by mass or more in a 1:1 (mass ratio) solution of ethanol at 25°C. (Polyvinyl alcohol 1) Nichigo G-plymer (AZF8035Q), manufactured by Mitsubishi Chemical Corporation, weight-average molecular weight 24,000, solids content 100% (Polyvinyl alcohol 2) Polyvinyl alcohol with vinyl acetate-derived structure / ethylene-derived structure / propylene-derived structure = 96 / 3 / 1 (mol%), weight-average molecular weight 48,000, solids content 100% (Polyvinyl alcohol 3) J-POVAL JF-05, manufactured by Nippon Vi-Poval Co., Ltd., weight-average molecular weight 22,000, solids content 100% (Polyvinyl alcohol 4) J-POVAL JF-17, manufactured by Nippon Bi-POVAL Co., Ltd., weight-average molecular weight 75,000, solids content 100% (Polyvinyl alcohol 5) KURARAY POVAL 60-98, manufactured by Kuraray Co., Ltd., weight-average molecular weight 106,000, solids content 100% (Polyethyleneimine) Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd., solid content 30%

[0250] [Table 1]

[0251] [Table 2]

[0252] The PEI content in the table means the content of polyalkyleneimine in the total amount of polyvinyl alcohol and polyalkyleneimine used in the preparation of the coating agent. The Tg in the table means the glass transition temperature of the dry coating film of each coating agent. The viscosity in the table means the viscosity of each coating agent at 25°C. For coating agents 7, 8, and 9, polyvinyl alcohol precipitated, and the viscosity could not be measured.

[0253] <Manufacture of Evaluation Samples> (Sample 1) On the first substrate, a coating agent was applied in a solid form using a gravure printing machine equipped with a gravure plate with a plate depth of 22 μm so that the coating amount (solid content) was 0.5 g / m 2 After drying by passing through an oven at 70°C, it was left at room temperature for 1 day to form the first resin layer.

[0254] Subsequently, an adhesive was applied onto the first resin layer, laminated with the second substrate, and aged at 40°C for 3 days to obtain Sample 1 of the first substrate / first resin layer / adhesive layer / second substrate.

[0255] (Sample 2) A first resin layer was provided on the first substrate in the same manner as in Sample 1. Next, a urethane-based laminating ink (FINAT R794 white, manufactured by DIC Corporation) was adjusted to 15 seconds (25°C) using a Rheonlab Zahn cup #3 manufactured by Rheon Co., Ltd., and printed in a solid form onto the first resin layer using a gravure printing machine equipped with a gravure plate with a plate depth of 43 μm, and dried or cured by passing through an oven at 70°C to form a printed layer.

[0256] Subsequently, an adhesive was applied onto the printed layer, laminated with the second substrate, and aged at 40°C for 3 days to obtain Sample 2 of the first substrate / first resin layer / printed layer / adhesive layer / second substrate.

[0257] (Sample 3) A first resin layer was provided on the first substrate in the same manner as in Sample 1. Furthermore, the coating agent was applied in a solid layer to the second substrate using a gravure printing press equipped with a gravure plate with a plate depth of 22 μm, dried by passing it through a 70°C oven, and then left at room temperature for one day to form a second resin layer.

[0258] Next, adhesive was applied to the first resin layer and bonded to the side of the second substrate where the second resin layer was provided. After aging at 40°C for 3 days, sample 3 was obtained consisting of the first substrate / first resin layer / adhesive layer / second resin layer / second substrate.

[0259] (Sample 4) A first resin layer was applied to the first substrate and a second resin layer to the second substrate in the same manner as in Sample 3. A printed layer was applied on the first resin layer in the same manner as in Sample 2. Adhesive was applied to the printed layer and bonded to the side of the second substrate on which the second resin layer was applied. After aging at 40°C for 3 days, Sample 4 was obtained, consisting of the first substrate / first resin layer / printed layer / adhesive layer / second resin layer / second substrate.

[0260] (Samples 5 and 6) Samples 5 and 6 were prepared in the same manner as samples 1 and 2, except that the first resin layer was omitted.

[0261] The combinations of the first substrate, second substrate, coating agent, and adhesive used in the manufacture of samples 1-6 are shown in Tables 4-17. Details of the first substrate, second substrate, and adhesive in the tables are as follows. Coating agents 7-9 could not be applied using the above method, and therefore could not be used to create evaluation samples.

[0262] (First base material) OPP: Manufactured by Toyobo Co., Ltd., P2161 (film thickness 20 μm) PET: Manufactured by Toyobo Co., Ltd., E5100 (film thickness 12 μm)

[0263] (Second base material) CPP: Manufactured by Toyobo Co., Ltd., P1128 (film thickness 30 μm) VMCPP: Manufactured by Toray Film Processing Co., Ltd., 2203 (film thickness 25 μm)

[0264] (glue) Adhesive 1: A mixture of DIC DRY® LX-470EL (manufactured by DIC Corporation) and SP-60 (manufactured by DIC Corporation), diluted with ethyl acetate, was used. The application rate (solid content) was 2.5 g / m². 2 After applying the adhesive, the solvent was dried with a hairdryer before bonding it to the CPP film. Adhesive 2: A mixture of 60 parts of DIC DRY® LX-500 and 1 part of KW-75, manufactured by DIC Corporation, was used and diluted with ethyl acetate. The application rate (solid content) was 2.5 g / m². 2 After applying the adhesive, the solvent was dried with a hairdryer before bonding it to the CPP film.

[0265] Adhesive 3: In a flask equipped with a stirrer, thermometer, and nitrogen gas inlet tube, 800 parts soybean oil, 225 parts maleic anhydride, and 0.5 parts phosphoric acid were charged and the temperature was raised to 180°C. After reacting at 180°C for 3 hours, the temperature was lowered to 100°C, and 200 parts tung oil was added and the mixture was reacted for another 3 hours to obtain an oil containing acid anhydride groups.

[0266] In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, and moisture separator, 220 parts of diethylene glycol, 344 parts of neopentyl glycol, 286 parts of adipic acid, 287 parts of isophthalic acid, and 0.1 parts of tetraisopropyl titanate were charged. The mixture was gradually heated so that the temperature at the top of the rectification tube did not exceed 100°C, and the internal temperature was maintained at 240°C. The esterification reaction was terminated when the acid value fell to 2.0 mhKOH / g or less, yielding a polyester polyol with a hydroxyl value of 180 mgKOH / g.

[0267] Adhesive 3 was prepared by mixing 100 parts of the acid anhydride group-containing oil synthesized above, 33.53 parts of polyester polyol, and 12.24 parts of ADEKA polyether EDP-450 (manufactured by ADEKA Corporation, a polypropylene glycol containing two tertiary amines in the molecule, molecular weight 450, hydroxyl value 500 mg KOH / g). The application amount (solid content) was 2.5 to 3.0 g / m². 2Then, after applying the adhesive, it was laminated with the CPP film.

[0268] <Evaluation> (Blocking resistance) Coating agents 1 to 6 were applied uniformly onto an OPP film (manufactured by Toyobo Co., Ltd., P2161) with a film thickness of 20 μm using a gravure printing machine equipped with a gravure plate with a plate depth of 22 μm, and dried by passing through an oven at 70 °C. After leaving it at room temperature for 1 day, the first resin layer was formed. An evaluation sample 7 of 5 cm × 5 cm was cut out from the OPP film on which the first resin layer was formed.

[0269] The untreated surface of a 5 cm × 5 cm OPP film was overlapped onto the first resin layer of evaluation sample 7, and a load of 0.5 kg / cm 2 was applied. After leaving it for 24 hours in an atmosphere at 40 °C and 80% humidity, the state when the evaluation sample and the OPP film were peeled off was evaluated according to the following criteria, and the results were summarized in Table 3. ◎: No peeling sound generated, no stain on the untreated surface of the OPP film ○: No peeling sound generated, no stain on the untreated surface of the OPP film, but slightly sticky feeling on the surface of the first resin layer △: Peeling sound generated, no stain on the untreated surface of the OPP film, but slightly sticky feeling on the surface of the first resin layer ×: Peeling sound generated, stain on the untreated surface of the OPP film

[0270]

Table 3

[0271] <I (Lamination strength) The laminate sample obtained above was cut into a length of 300 mm and a width of 15 mm to be used as a test piece. Using an Instron type tensile testing machine, under an environment at 25 °C, it was pulled at a peeling speed of 300 mm / min, and the T-type peeling strength (N) was measured. This test was conducted 5 times, and the average value was obtained and evaluated according to the following criteria, and the results were summarized in Tables 4 to 17. 〇: 0.5 N / 15 mm or more ×: 0.5N / less than 15mm

[0272] (Non-laminating properties) The laminate samples obtained above were cut into 20mm x 20mm pieces to prepare test specimens. The test specimens were immersed in treatment solution 1 (2% NaOH aqueous solution) at 70°C, stirred at 400 rpm for 1 hour using a magnetic stirrer, and then removed. After washing and drying with deionized water, the adhesive peel area (%) was examined and evaluated according to the following criteria, and the results are summarized in Tables 4 to 17. The delamination properties were evaluated in the same manner as above, except that treatment solution 2 (hot water) was used instead of treatment solution 1. The results are summarized in Tables 4 to 17. 5. The first and second substrates are 100% separated, and the printed layer and adhesive layer are completely separated from either the first or second substrate. The first substrate, second substrate, printing layer, and adhesive layer can be recovered separately. 4: The first and second substrates are 100% separated, but a portion of the printed layer or adhesive layer remains on either the first or second substrate. 3: The peeling area between the first and second substrates is 50% or more but less than 100%. 2: The peeling area between the first and second substrates is 10% or more but less than 50%. 1: The peeling area between the first and second substrates is less than 10%.

[0273] (Recyclability) The release agent after the delamination test was filtered through a nylon strainer with a mesh size of 90 mesh / inch and an aperture of 185 μm. The condition of the filtered laminated sample and the presence or absence of discoloration of the release agent after filtration were visually inspected. The results were evaluated in the following two stages and summarized in Tables 4-17. ○: The first substrate, the second substrate, and the printed layer fragments / adhesive fragments can be recovered separately; no discoloration is observed in the release agent after filtration. ×: The first substrate, the second substrate, and the printed layer fragments / adhesive fragments could not be recovered separately; discoloration was observed in the release agent after filtration.

[0274] [Table 4]

[0275] Table 5

[0276] Table 6

[0277] Table 7

[0278] Table 8

[0279] Table 9

[0280] Table 10

[0281] Table 11

[0282] Table 12

[0283] Table 13

[0284] Table 14

[0285] Table 15

[0286] Table 16

[0287] Table 17

Claims

1. The first base material and The second substrate and An adhesive layer disposed between the first substrate and the second substrate, It includes a first resin layer disposed between the first substrate and the adhesive layer, The first resin layer comprises a first vinyl alcohol-based polymer and a first polyalkyleneimine. The first vinyl alcohol polymer is soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, and the viscosity of the solution in which the vinyl alcohol polymer is dissolved at 5% by mass in a 1:1 (mass ratio) solution of water and ethanol at 25°C is 200 mPa·s or less. A laminate in which the glass transition temperature of the first resin layer is 40°C or higher and 80°C or lower.

2. The laminate according to claim 1, wherein the glass transition temperature of the first resin layer is 50°C or more and 70°C or less.

3. The laminate according to claim 1, wherein the content of the first polyalkyleneimine in relation to the total amount of the first vinyl alcohol polymer and the first polyalkyleneimine is 1% by mass or more and 25% by mass or less.

4. A second resin layer is included between the adhesive layer and the second substrate. The second resin layer comprises a second vinyl alcohol-based polymer and a second polyalkyleneimine. The second vinyl alcohol polymer is soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, and the viscosity of the solution in which the vinyl alcohol polymer is dissolved at 5% by mass in a 1:1 (mass ratio) solution of water and ethanol at 25°C is 200 mPa·s or less. The laminate according to claim 1, wherein the glass transition temperature of the second resin layer is 40°C or higher and 80°C or lower.

5. The laminate according to claim 1, having a metal vapor deposition layer or an inorganic vapor deposition layer between the first substrate and the first resin layer.

6. The laminate according to claim 1, having a printed layer between the first resin layer and the adhesive layer.

7. A recycling method comprising a peeling step of immersing a laminate in a peeling agent to separate the first substrate from the second substrate, the laminate comprising a first substrate, a second substrate, an adhesive layer disposed between the first substrate and the second substrate, wherein the first resin layer comprises a first polyvinyl alcohol and a first polyalkylene imine, the first vinyl alcohol polymer is soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, and the viscosity of a solution obtained by dissolving 5% by mass of the vinyl alcohol polymer in a 1:1 (mass ratio) solution of water and ethanol at 25°C is 200 mPa·s or less, and the glass transition temperature of the first resin layer is 40°C or more and 80°C or less.

8. The recycling method according to claim 7, wherein the release agent is heated to 55°C or higher and 85°C or lower.

9. The recycling method according to claim 7, wherein the release agent is hot water at a temperature of 55°C or higher and 85°C or lower.

10. The recycling method according to claim 7, wherein the release agent is recovered, filtered through a filter having an aperture diameter of 10 μm or more and 200 μm or less, and then reused.

11. The recycling method according to claim 7, wherein the laminate includes a second resin layer between the adhesive layer and the second substrate, the second resin layer comprises a second vinyl alcohol polymer and a second polyalkylene imine, the second vinyl alcohol polymer is soluble in a 1:1 (mass ratio) solution of water and ethanol at 25°C at a concentration of 5% by mass or more, the viscosity of the solution obtained by dissolving 5% by mass of the vinyl alcohol polymer in a 1:1 (mass ratio) solution of water and ethanol at 25°C is 200 mPa·s or less, and the glass transition temperature of the second resin layer is 40°C or more and 80°C or less.

12. A separation and recovery step for recovering the first substrate from the peeling agent after the peeling step, The recycling method according to claim 7, further comprising a pelletizing step of melting and kneading the first base material recovered in the separate collection step.

13. The recycling method according to claim 12, wherein in the pelletizing step, the first substrate recovered in the sorting and collection step and virgin plastic of the same resin type as the first substrate are melted and kneaded.

14. The recycling method according to claim 13, wherein the mass ratio of the first substrate to the virgin plastic is 100:0 to 25:75.

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