Methods for recycling laminates

Abstract

This invention provides a method for recycling packaging used in food packaging and other applications, as well as laminates used in the manufacture of such packaging. [Solution] A recycling method comprising a peeling step of immersing a laminate, which includes a first substrate, a second substrate, and an adhesive layer for bonding the first substrate and the second substrate, wherein the adhesive layer is a cured coating film of a two-component curing adhesive consisting of a polyol composition and a polyisocyanate composition containing a polyisocyanate compound, in a release agent to peel off the first substrate and the second substrate.

Description

[Technical Field]

[0001] The present invention relates to a method for recycling laminates. [Background technology]

[0002] In recent years, environmental pollution caused by the disposal and dumping of plastic products has become a serious concern, leading to increased demand for plastic product recycling. Among plastic products, plastic film packaging materials generally have a multilayer structure to meet different performance requirements depending on the application. For example, food packaging consists of a laminated structure formed by printing ink onto a first substrate and bonding it to a second substrate via an adhesive layer as needed. This laminated structure is then cut and heat-sealed to form the package shape. In such laminated structures, typified by food packaging, various plastic substrates are used as film substrates, including polyester, nylon, polypropylene, and polyethylene. Therefore, there is a demand for material recycling of laminated structures.

[0003] To address these demands, studies are underway to explore material recycling of laminated materials such as food packaging. For example, Patent Document 1 discloses a method in which impurities contained in the package are removed, the package is crushed, and after alkaline treatment or other necessary processes are performed, the materials are separated and recovered according to their specific gravity, and then the separated raw materials are melted to form pellets. Patent Document 2 discloses a method for manufacturing recycled plastic in which a laminate is melted and kneaded without performing a step to separate or detach layers other than the plastic substrate, such as the adhesive layer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-019003 [Patent Document 2] Patent No. 7425948 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a method for recycling packaging used in food packaging and the like, and laminates used in the manufacture of such packaging. [Means for solving the problem]

[0006] The present invention relates to a recycling method comprising a laminate including a first substrate, a second substrate, and an adhesive layer for bonding the first substrate and the second substrate, wherein the adhesive layer is a cured coating film of a two-component curing adhesive consisting of a polyol composition and a polyisocyanate composition containing a polyisocyanate compound, and the laminate is immersed in a release agent to separate the first substrate and the second substrate. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for recycling packaging used in food packaging and the like, and laminates used in the manufacture of such packaging. [Modes for carrying out the invention]

[0008] <Recycled materials> Prior to describing the recycling method of the present invention, the materials used in the recycling method of the present invention (materials recycled by the recycling method of the present invention) will be described. Examples of recycled materials used in the present invention include laminates comprising a first base material, a second base material, and an adhesive layer that bonds the first base material and the second base material, and packaging materials made by forming a bag from the laminate.

[0009] (Laminated structure) (First base material) The first substrate can be any film or sheet (unless otherwise specified, "film" here also refers to both films and sheets) that has excellent chemical and physical strength, without any particular limitations. Examples of the first substrate include polyethylene terephthalate (PET) film, polystyrene film, polyamide film, polyacrylonitrile film, polyethylene film (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film, MDOPE: uniaxially oriented polyethylene film, OPE: biaxially oriented polyethylene film), polypropylene film (CPP: unoriented polypropylene film, OPP: biaxially oriented polypropylene film), polyolefin film such as ethylene vinyl alcohol copolymer, or polyvinyl alcohol copolymer film, which is a gas barrier film in which an olefin-based heat-sealable resin layer is provided on one or both sides of a gas barrier resin such as polyvinyl alcohol.

[0010] Furthermore, it is preferable to use a film formed from materials containing biomass-derived components. Biomass films are sold by various companies, and for example, sheets listed in the biomass certified product list provided by the Japan Organic Resources Association can be used.

[0011] A well-known example of a film made from biomass-derived ethylene glycol is derived from ethanol produced from biomass (biomass ethanol). For example, biomass-derived ethylene glycol can be obtained by conventionally known methods, such as a method that produces ethylene glycol via ethylene oxide from biomass ethanol. Alternatively, commercially available biomass ethylene glycol may be used; for example, the biomass ethylene glycol commercially available from India Glycol can be suitably used.

[0012] Alternatively, products using biomass raw materials, distinguished by their biomass plasticity as defined by ISO 16620 or ASTM D6866, are also available. Radioactive carbon-14C exists in the atmosphere at a rate of 1 in 10¹² atoms, and this rate does not change even in atmospheric carbon dioxide. Therefore, this rate does not change in plants that fix carbon dioxide through photosynthesis. For this reason, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the proportion of plant-derived resin in the resin, i.e., the biomass plasticity, can be determined. Examples of plant-derived low-density polyethylene (PPE) biomass plastics with a biomass plastic content of 80% or more, preferably 90% or more, as defined by ISO 16620 or ASTM D6866, include Braskem's product names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films made from these materials can be suitably used.

[0013] The film may be stretched. A common stretching method involves melting and extruding the resin into a sheet using methods such as extrusion film formation, followed by simultaneous biaxial stretching or sequential biaxial stretching. In the case of sequential biaxial stretching, it is common to first perform longitudinal stretching, followed by transverse stretching. Specifically, a method combining longitudinal stretching using the speed difference between rolls and transverse stretching using a tenter is frequently used.

[0014] Various surface treatments, such as flame treatment or corona discharge treatment, may be applied to the film surface as needed to ensure that an adhesive layer free from defects such as film breakage or repulsion is formed.

[0015] Alternatively, an inorganic vapor deposition film such as a metal vapor deposition film obtained by vapor depositing a metal layer such as aluminum, or a transparent vapor deposition film having a vapor deposition layer of a metal oxide such as silica or alumina laminated thereon, or a barrier film containing a gas barrier layer such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, or vinylidene chloride may be used. When a basic compound is contained in the peeling liquid for separating the laminate in the recycling process described later, such a film is preferable because the vapor deposition layer is easily dissolved in the peeling liquid, and the printing layer and the adhesive are more easily peeled from the resin film.

[0016] The film thickness of the first substrate is not particularly limited, and may be appropriately selected within the range of 1 to 300 μm from the viewpoints of moldability and transparency. Preferably, it is in the range of 1 to 100 μm.

[0017] (Second substrate) The same material as the first substrate can be used for the second substrate. In one embodiment of the present invention, the second substrate is a film (sealant film) having heat sealability that can be melted by heat and fused to each other, and the first substrate is a substrate not expected to serve as a sealant film. In another embodiment of the present invention, the second substrate is a film in which a film having no heat sealability and a resin layer having heat sealability (heat seal layer) are laminated, and the first substrate is a substrate not expected to serve as a sealant film.

[0018] 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.

[0019] Any type of sealant film can be used, including unstretched, uniaxially oriented, and biaxially oriented films.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] (Adhesive layer) The adhesive layer is formed by applying an adhesive directly or via an optional layer to either the first or second substrate, bonding it to the other substrate, and then performing an aging treatment. Alternatively, the adhesive layer is formed by applying a polyol composition directly or via an optional layer to either the first or second substrate, applying a polyisocyanate composition directly or via an optional layer to the other substrate, bonding the first and second substrates together so that the polyol composition and the polyisocyanate composition are in contact, and then performing an aging treatment. Examples of adhesives include two-component curing adhesives containing a polyol composition and a polyisocyanate composition.

[0033] Polyol compositions include 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.

[0034] 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.

[0035] 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;

[0036] Trimethylolethane, trimethylolpropane, glycerin, hexanetriol, pentaerythritol, and other trifunctional or greater aliphatic polyols; Polyhydric alcohols such as 1,3,5-tris(2-hydroxyethyl)isocyanuric acid or 1,3,5-tris(2-hydroxypropyl)isocyanuric acid;

[0037] Bisphenols such as bisphenol A and bisphenol F; bisphenol alkylene oxide adducts obtained by adding ethylene oxide, propylene oxide, etc., to bisphenols such as bisphenol A and bisphenol F;

[0038] 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.

[0039] 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.

[0040] The molecular weight of polyester polyols is not particularly limited, but as an example, the number average molecular weight is between 250 and 20,000. 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.

[0041] 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.

[0042] 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;

[0043] Trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol, and triol compounds of polypropylene glycol;

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Examples of sugar alcohols include pentaerythritol, sucrose, xylitol, sorbitol, isomalt, lactitol, maltitol, and mannitol.

[0049] The polyol composition may contain an amine compound. The amine compound is a compound having an amino group. In this specification, an amino group refers to an NH2 group or an NHR group (where R is an alkyl or aryl group which may have a functional group).

[0050] Any known amine compound can be used without particular limitation, including methylenediamine, ethylenediamine, isophoronediamine, 3,9-dipropanamine-2,4,8,10-tetraoxaspirodoundecane, lysine, 2,2,4-trimethylhexamethylenediamine, hydrazine, piperazine, 2-hydroxyethylethylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, poly(propylene glycol)diamine, poly(propylene glycol)triamine, poly(propylene glycol)tetraamine, 1,2-diaminopropane, 1,3-diaminopropane,

[0051] 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, nonaethylenedecamine, trimethylhexamethylenediamine, tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, triethylene-bis(trimethylene)hexamine, bis(3-aminoethyl)amine, bishexamethylenetriamine, 1,4-cyclohexanediamine, 4,4'-methylenebiscyclohexylamine, 4,4'-isopropylidenebiscyclohexylamine, norbornadiamine,

[0052] Amine compounds having multiple amino groups, such as bis(aminomethyl)cyclohexane, diaminodicyclohexylmethane, isophoronediamine, mensendiamine, bis(cyanoethyl)diethylenetriamine, 1,4-bis-(8-aminopropyl)-piperazine, piperazine-1,4-diazacycloheptane, 1-(2'-aminoethylpiperazine), 1-[2'-(2"-aminoethylamino)ethyl]piperazine, tricyclodecanediamine, and polyureamines which are reaction products of the aforementioned polyamines and the aforementioned isocyanate components.

[0053] Primary or secondary alkanolamines such as monoethanolamine, monoisopropanolamine, monobutanolamine, N-methylethanolamine, N-ethylethanolamine, N-methylpropanolamine, diethanolamine, and diisopropanolamine.

[0054] Examples include primary or secondary amines such as ethylamine, octylamine, laurylamine, myristylamine, stearylamine, oleylamine, diethylamine, dibutylamine, and distearylamine.

[0055] The amount of amine compound can be adjusted as appropriate depending on the purpose, but as an example, it is preferable to adjust the amine value of the polyol composition to be between 1 mg KOH / g and 100 mg KOH / g, and preferably between 10 mg KOH / g and 80 mg KOH / g.

[0056] In this specification, the amine value refers to the number of milligrams of KOH equivalent to the amount of HCl required to neutralize 1 g of the sample. There are no particular restrictions, and it can be calculated using known methods. If the chemical structure of the amine compound (E7) and, if necessary, the average molecular weight are known, it can be calculated using the formula: (number of amino groups per molecule / average molecular weight) × 56.1 × 1000. If the chemical structure or average molecular weight of the amine compound is unknown, it can be measured according to known amine value measurement methods, such as JIS K7237-1995.

[0057] 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.

[0058] 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.

[0059] 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).

[0060] 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.

[0061] 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.

[0062] 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.

[0063] The polyisocyanate composition may contain, for example, 5 to 50% by mass of diisocyanate monomer for the purpose of adjusting its viscosity to be suitable for the non-solvent lamination method, or its content may be reduced to 5% by mass or less, more preferably 1% by mass or less, more preferably 0.5% by mass or less, and more preferably 0.1% by mass or less of the polyisocyanate composition from the viewpoint of occupational safety and health.

[0064] The diisocyanate monomer can be removed by distilling it under reduced pressure using a short-pass distillation apparatus or a thin-film distillation apparatus. The degree of reduced pressure and distillation temperature are adjusted as appropriate depending on the diisocyanate monomer to be removed, but as an example, they are 0.1 mbar or less and 120°C to 190°C. The diisocyanate monomer removal process may be performed multiple times.

[0065] The diisocyanate monomer content can be measured by gas chromatography using an internal standard, for example, according to ASTM D 3432. Alternatively, it can be measured by liquid chromatography under the following conditions.

[0066] Equipment: Waters Corporation "ACQUITY UPLC H-Class" Data processing: Empower-3 manufactured by Waters Corporation Column: Waters Corporation "ACQUITY UPLC HSS T3" (100 mm × 2.1 mmφ, 1.8 μm) 40℃ Eluent: Ammonium formate aqueous solution / methanol, 0.3 mL / min Detector: PDA Sample preparation: 1. Dissolve 100 mg of appropriately blocked sample in 10 ml of THF (for LC). 2. Vortex for 30 seconds. 3. Dilute as appropriate with the eluent (mobile phase). The liquid was passed through a 4.0.2 μm filtration filter to obtain the measurement sample. Calculation of area ratio: Calculated using the maximum absorption wavelength for the target material.

[0067] The adhesive 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 due to incomplete removal of the components of the polyol composition and polyisocyanate composition or organic solvents used as reaction media during the manufacture of their raw materials, it is understood that the adhesive is substantially solvent-free. Furthermore, if the polyol composition contains 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 low molecular weight alcohols are not considered organic solvents.

[0068] The adhesive may contain components other than those mentioned 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 or the polyisocyanate composition, or they may be prepared separately and mixed with the polyol composition or polyisocyanate composition immediately before application of the adhesive.

[0069] It is preferable to use the adhesive in a formulation such that the ratio [NCO] / [OH] of the number of moles of isocyanate groups [NCO] contained in the polyisocyanate composition to the number of moles of hydroxyl groups [OH] contained in the polyol composition is 0.5 to 5.0.

[0070] The adhesive layer is formed by applying an adhesive directly or via an optional layer to either the first or second substrate, bonding it to the other substrate, and then performing an aging treatment. Alternatively, the adhesive layer is formed by applying a polyol composition directly or via an optional layer to either the first or second substrate, applying a polyisocyanate composition directly or via an optional layer to the other substrate, bonding the first and second substrates together so that the polyol composition and the polyisocyanate composition are in contact, and then performing an aging treatment. As an example, the aging temperature is room temperature to 70°C, and the aging time is 6 to 240 hours. The amount of adhesive applied is adjusted as appropriate, but as an example, it is 1 g / m². 2 More than 5g / m 2 The following applies:

[0071] (Printing layer) The laminate used in the present invention may include a first substrate, a second substrate, an adhesive layer, and a printed layer. The printed layer is a layer printed using printing ink between the first substrate and the adhesive layer, or on the surface of the first substrate opposite the adhesive layer, and may form characters, figures, symbols, or other desired patterns or information.

[0072] The printing method and ink used to form the printed layer are not particularly limited, and known printing methods and inks can be used. The films used as the substrate often employ printing inks produced using gravure printing, flexographic printing, lithographic offset printing, and inkjet recording printing methods. Printing inks combining these methods with curing methods using active energy rays such as ultraviolet (UV), LEDs, or electron beams (EB), or curing methods using heat, are also used. Furthermore, depending on the solvent used, these may be referred to as water-based inks or organic solvent-based inks.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] For biomass gravure printing inks or flexographic printing inks, commercially available products listed by the Japan Organic Resources Association can also be used.

[0081] (Desorption layer) The laminate used in the present invention may include a delamination layer in addition to a first substrate, a second substrate, and an adhesive layer. The delamination layer is a layer that has the property of peeling off from the substrate when immersed in a release agent described later for a certain period of time. By placing such a layer, for example, between the printed layer and the first substrate, the substrate and the printed layer become easier to peel off when immersed in the release agent in the recycling method of the present invention, and the laminate and packaging material used in the recycling method of the present invention become more recyclable. The delamination layer is not particularly limited as long as it has such a function, but the following embodiments can be given as examples.

[0082] (Desorption layer (1)) One embodiment of the desorption layer includes one containing a vinyl alcohol-based polymer and a polyalkylene imine. Such a desorption layer (1) can be formed, for example, by applying a coating agent containing a vinyl alcohol-based polymer, a polyalkylene imine, and an aqueous solvent onto a first substrate and drying the solvent.

[0083] The 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.

[0084] 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.

[0085] 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.

[0086] 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%.

[0087] Vinyl alcohol polymers 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.

[0088] 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.

[0089] 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.

[0090] It is preferable to use a vinyl alcohol polymer 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 200 mPa·s or less. 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.

[0091] While vinyl alcohol polymers exhibit excellent solubility in water, many have poor solubility in low-molecular-weight alcohols such as ethanol, and such polymers dissolve only slightly in a cosolvent of water and ethanol. By selecting and using polymers with excellent solubility in a cosolvent of water and ethanol, the coating agent used for forming the desorption layer can be made to have excellent coating properties even with a high solid content, and a coating film of an appropriate thickness can be efficiently formed as the desorption layer. Furthermore, less energy is required to volatilize the solvent from the coating agent during desorption layer formation, 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 one example is 90% or higher.

[0092] Polyalkyleneimines are resins having a polyalkyleneimine skeleton and can be obtained by polymerizing one or more alkyleneimines (e.g., ethyleneimine, propyleneimine) by conventional methods.

[0093] Polyalkyleneimines may be linear polyalkyleneimines consisting of linear polyalkyleneimines, or branched polyalkyleneimines having branched polyalkyleneimines. Examples of polyalkyleneimines include polyethyleneimine and polypropyleneimine. Polyalkyleneimines may also have substituents (e.g., hydroxypropyl groups, hydroxyethyl groups) 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.

[0094] Polyalkyleneimines are thought to contribute to improved adhesion between vinyl alcohol polymers and olefin films due to their amino groups (NHR groups, NH2 groups) and ethylene groups. Because they are effective in improving adhesion, it is preferable that the polyalkyleneimines include branched polyalkyleneimines.

[0095] The number-average molecular weight of polyalkyleneimines is typically between 5,000 and 100,000. The number-average molecular weight of polyalkyleneimines was measured using GPC (gel permeation chromatography) with pullulan as the standard substance.

[0096] From the viewpoint of balancing the adhesive strength of the laminate with suppression of blocking when winding after forming the desorption layer (1), it is preferable that the amount of polyalkylimine in the desorption layer (1) is 1% by mass or more and 25% by mass or less of the total amount of vinyl alcohol polymer and polyalkylimine.

[0097] The desorption layer (1) may contain resins other than vinyl alcohol polymers and polyalkylimines. 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 vinyl alcohol polymer and polyalkyleneimines. More preferably 5% by mass or less, and even more preferably 1% by mass or less. It may also be 0% by mass.

[0098] The desorption layer (1) preferably 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 desorption layer (1), resulting in a laminate with excellent adhesive strength and recyclability. The glass transition temperature of the desorption layer (1) can be adjusted by the vinyl alcohol polymer, polyalkylene imine used, and their blending ratio. The glass transition temperature of the desorption layer (1) is more preferably 50°C or higher, and more preferably 70°C or lower.

[0099] 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.

[0100] 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.

[0101] The coating agent used to form the desorption layer (1) may further contain additives. Examples of additives include crosslinking agents that react with the functional groups of vinyl alcohol polymers or polyalkylimines, inorganic fillers, defoamers, leveling agents, stabilizers (antioxidants, heat stabilizers, UV absorbers, etc.), plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, leveling agents, etc.

[0102] 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.

[0103] 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.

[0104] The resin content in the coating agent, including vinyl alcohol polymers and polyalkyleneimines, 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 it is adjusted so that the viscosity at 25°C does not exceed 300 mPa·s.

[0105] 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.

[0106] The thickness of the desorption layer (1) can be adjusted as appropriate, but as an example, it is between 0.1 μm and 2.0 μm.

[0107] (Desorption layer (2)) Another embodiment of the desorption layer includes one containing a urethane resin having ester bonds. Such a desorption layer (2) can be formed, for example, by applying a coating agent containing a urethane resin and a solvent onto a first substrate and drying the solvent. Either an organic solvent or an aqueous solvent can be used as the solvent.

[0108] Urethane resins containing ester bonds are obtained by reacting polyester polyols with polyisocyanates. Polyester polyols can be produced by esterifying polycarboxylic acids with polyols.

[0109] Examples of polycarboxylic acids used in the production of polyester polyols include dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, and 1,2-bis(phenoxy)ethane-P,P'-dicarboxylic acid, as well as their acid anhydrides or ester-forming derivatives; aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and their ester-forming derivatives; sulfonic acid group-containing aromatic dicarboxylic acids such as 5-sulfisophthalic acid and their ester-forming derivatives; aliphatic dicarboxylic acids such as succinic acid, succinic anhydride, adipic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, maleic anhydride, and fumaric acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, as well as their anhydrides or ester-forming derivatives. These may be used individually or in combination of two or more.

[0110] As the polycarboxylic acid, adipic acid is preferred, and it is preferable that 50% or more by mass of the polycarboxylic acid used in the production of the polyester polyol is adipic acid.

[0111] Examples of polyols used in the production of polyester polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, and neopentyl glycol. These may be used individually or in combination of two or more.

[0112] It is preferable to use diethylene glycol or ethylene glycol, and it is preferable that 50% by mass or more of the polyol used in the production of the polyester polyol is diethylene glycol or ethylene glycol.

[0113] Polyester polyols are obtained by reacting these polycarboxylic acids and polyols under atmospheric or reduced pressure in a reaction vessel purged with an inert gas such as nitrogen, in the presence of a catalyst as needed. The reaction temperature is preferably 100°C to 300°C.

[0114] As catalysts, for example, acetates of alkali metals or alkaline earth metals, or compounds containing zinc, manganese, cobalt, antimony, germanium, titanium, tin, zirconium, etc., can be used. It is preferable to use tetraalkyl titanates or tin oxalate, which are effective in transesterification and polycondensation reactions.

[0115] Polyisocyanates used in the synthesis of urethane resins having ester bonds include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate, and aliphatic or aliphatic cyclic structure-containing diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate, which can be used alone or in combination of two or more. It is preferable to use one or more selected from the group consisting of isophorone diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

[0116] The polyisocyanate preferably contains isophorone diisocyanate, and it is preferable that 50% or more by mass of the polyisocyanate is isophorone diisocyanate.

[0117] For the synthesis of urethane resins having ester bonds, polyols other than polyester polyols, polyamines, and water may be used in combination as chain extenders. Examples of polyols other than polyester polyols include glycols such as methylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, neopentyl glycol, saccharose, glycerin, and sorbitol; and phenols such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone.

[0118] Polyamines include diamines such as ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, and 1,4-cyclohexanediamine; N-hydroxymethylaminoethylamine, N-hydroxyethylaminoethylamine, N-hydroxypropylaminopropylamine, N-ethylaminoethylamine, and N-methylamino Examples include propylamine; diethylenetriamine, dipropylenetriamine, triethylenetetramine; hydrazine, N,N'-dimethylhydrazine, 1,6-hexamethylenebishydrazine; succinate dihydrazide, adipic acid dihydrazide, glutarate dihydrazide, sebacate dihydrazide, isophthalate dihydrazide; β-semicarbazide propionic acid hydrazide, 3-semicarbazide-propylcarbasic acid ester, semicarbazide-3-semicarbazidemethyl-3,5,5-trimethylcyclohexane, etc.

[0119] The weight-average molecular weight of the urethane resin is adjusted as appropriate, but as an example, it is between 10,000 and 100,000. When the urethane resin is dissolved in an organic solvent and applied, the weight-average molecular weight is preferably between 20,000 and 60,000, and when it is dispersed in an aqueous solvent and applied, the weight-average molecular weight is preferably between 30,000 and 80,000.

[0120] The glass transition temperature of the urethane resin is preferably between 0 and 110°C.

[0121] Urethane resins having ester bonds are obtained by reacting a polyester polyol with a polyisocyanate in the presence of an organic solvent. When a chain extender is used in combination with the synthesis of the urethane resin, it may be reacted together with the polyester polyol and polyisocyanate, or the chain extender may be reacted after the polyester polyol and polyisocyanate have been reacted.

[0122] Organic solvents used in the synthesis of urethane resins include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetic acid esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; and dimethylformamide and N-methylpyrrolidone, which can be used individually or in combination of two or more.

[0123] When the solvent contained in the coating agent is an organic solvent (hereinafter also referred to as when the coating agent is solvent-based), from the viewpoint of balancing the peelability of the delamination layer (2) and the solubility of the urethane resin in the coating agent, it is preferable to use a urethane resin in which the ester bond group concentration is 3 mmol / g to 9 mmol / g and the R (HSP distance) represented by the following formula (1) is 9 or less.

[0124]

number

[0125] R (HSP distance) is an indicator of the solubility of an organic solvent in a polyester polyol. A lower value indicates better solubility, and in this invention, R is 9 or less. Preferably, R (HSP distance) is 8 or less, and more preferably 7 or less. Furthermore, preferably R (HSP distance) is 3 or more, and more preferably 5 or more.

[0126] The ester bond group concentration can be determined by calculating the number of moles of ester bond groups contained in 1 g of urethane resin. The ester bond group concentration is preferably 4 mmol / g or more, more preferably 5 mmol / g or more, from the viewpoint of improving the adhesion and deinking properties of the desorption layer (2) to the substrate, and preferably 8 mmol / g or less, more preferably 7 mmol / g or less, from the viewpoint of good blocking resistance of the primer layer.

[0127] When the coating agent is solvent-based, the acid value of the urethane resin is not particularly limited, but as an example, it is 15 mg KOH / g or less. The acid value is calculated by titrating the acid with an alkali and converting the amount of acid per gram of resin to the number of milligrams of potassium hydroxide, according to JIS K0070. The acid value of the urethane resin may also be 0 mg KOH / g.

[0128] When the coating agent is solvent-based, the urethane resin has, for example, a urea group concentration of 0.2 mmol / g or more, another example of 0.3 mmol / g or more, and yet another example of 0.6 mmol / g or more. Furthermore, the urea group concentration of the urethane resin is, for example, 2 mmol / g or less, another example of 1.7 mmol / g or less, and yet another example of 1.5 mmol / g or less. The urea group concentration is the value obtained by dividing the weight of the diamine contained in 1 g of urethane resin by the NCO equivalent mass of the constituting diamine.

[0129] Organic solvents used in the preparation of coating agents include acetic acid esters such as ethyl acetate and butyl acetate; alcohols such as methanol, ethanol, n- and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycols; and N-methyl-2-pyrrolidone. Since coating materials widely used on plastic substrates require consideration for the health of workers and the environment, it is preferable to use toluene-free and methyl ethyl ketone (MEK)-free organic solvents, with ethyl acetate and isopropyl alcohol being preferred.

[0130] From the viewpoint of improving the compatibility between the polyester polyol used in the synthesis of urethane resin and the organic solvent used in the preparation of the coating agent, and reducing the R (HSP distance), it is preferable that the content of ethyl acetate in the organic solvent be 60% by weight or more and 100% by weight or less, and the content of isopropyl alcohol be 0% by weight or more and 40% by weight or less. It is more preferable that the content of ethyl acetate be 70% by weight or more, and even more preferable that it be 80% by weight or more.

[0131] When the solvent contained in the coating agent is an aqueous solvent (hereinafter also referred to as when the coating agent is aqueous), from the viewpoint of balancing the peelability of the delamination layer (2) and the water dispersion stability of the urethane resin in the coating agent, it is preferable to use a urethane resin having an ester bond group concentration of 1 mmol / g or more and an acid value of 8 mg KOH / g to 45 mg KOH / g.

[0132] The ester bond group concentration of the urethane resin is preferably 2 mmol / g or more, more preferably 4 mmol / g or more, and from the viewpoint of good blocking resistance of the desorption layer (2), it is preferably 9 mmol / g or less, and more preferably 7 mmol / g or less. The acid value of the urethane resin is preferably 15 mgKOH / g or higher, more preferably 20 mgKOH / g or higher, preferably 40 mgKOH / g or lower, and more preferably 30 mgKOH / g or lower.

[0133] When the coating agent is aqueous, the value obtained by dividing the mass of polyisocyanate raw material monomers contained in 1 g of urethane resin by the NCO equivalent mass of polyisocyanate raw material monomers is preferably 1.0 to 6.0 mmol / g. If this value is 1.0 mmol / g or more, the adhesion and deinking properties of the desorption layer (2) to the substrate can be improved. It is more preferably 1.5 mmol / g or more, and even more preferably 1.8 mmol / g or more. If it is 6.0 mmol / g or less, the film-forming properties of the desorption layer (2) can be ensured, it is more preferably 5.0 mmol / g or less, and even more preferably 4.0 mmol / g or less.

[0134] When the coating agent is aqueous, the aromatic ring concentration derived from the raw material monomer of the aromatic dicarboxylic acid in the urethane resin is preferably 1 mmol / g or more. This aromatic ring concentration can be determined by calculating the number of moles of aromatic rings contained in 1 g of urethane resin. From the viewpoint of improving the adhesion and deinking properties of the resulting desorption layer (2), the aromatic ring concentration is preferably 1.5 mmol / g or more, more preferably 2 mmol / g or more, and from the viewpoint of good film-forming properties of the primer layer, it is preferably 6 mmol / g or less, more preferably 5 mmol / g or less.

[0135] Organic solvents used in the preparation of coating agents include, as aqueous solvents, water, organic solvents miscible with water, and mixtures thereof. Examples of organic solvents miscible with water include alcohols such as methanol, ethanol, n- and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycols; and N-methyl-2-pyrrolidone. Water alone may be used, a mixture of water and a water-miscible organic solvent may be used, or a water-miscible organic solvent may be used alone. From the standpoint of safety and environmental impact, water alone or a mixture of water and a water-miscible organic solvent is preferred, and water alone is particularly preferred.

[0136] When the coating agent is aqueous, the urethane resin content is preferably 5% to 50% by mass, and more preferably 10% to 25% by mass, relative to the total amount of the coating agent. Furthermore, the aqueous solvent is preferably contained in an amount of 50% to 95% by mass, and more preferably 75% to 90% by mass, relative to the total amount of the urethane resin composition.

[0137] The coating agent (solvent-based coating agent and aqueous coating agent) used to form the desorption layer (2) may also be used in combination with a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amino-based crosslinking agents, aziridine-based crosslinking agents, silane coupling agent-based crosslinking agents, carbodiimide-based crosslinking agents, and oxazolidine-based crosslinking agents. It is preferable to use a polyisocyanate crosslinking agent. The crosslinking agent is preferably used in an amount of 30% by mass or less, and more preferably in an amount of 20% by mass or less, relative to the total amount of urethane resin having ester bonds, from the viewpoint of improving adhesion to the substrate and improving deinking properties. It is also preferable to mix the crosslinking agent immediately before applying the coating agent to the substrate.

[0138] The coating agent used to form the desorption layer (2) may contain various additives as needed, such as film-forming aids, curing accelerators, plasticizers, antistatic agents, waxes, light stabilizers, flow regulators, dyes, leveling agents, rheology control agents, ultraviolet absorbers, antioxidants, photocatalytic compounds, inorganic pigments, organic pigments, extender pigments, etc. It is preferable to use these additives in an amount of 5% by mass or less relative to the total amount of the coating agent.

[0139] The method of applying the coating agent is not particularly limited and can be provided in the same manner as the desorption layer (1). The thickness of the desorption layer (2) can be adjusted as appropriate, but as an example, it is between 0.1 μm and 2.0 μm.

[0140] (Third base material) The laminate used in 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, while the first and third substrates are substrates that are not expected to act as sealant films. In another embodiment of the present invention, the first, second, and third substrates are all substrates that are not expected to act as sealant films. When the laminate used in the present invention includes a third substrate, the third substrate is, for example, placed between the first substrate and the second substrate.

[0141] (Barrier coat layer) The laminate used in the present invention may include a barrier coating layer in addition to the layers described above. The barrier coating layer is a layer that prevents the permeation of oxygen and water vapor, and can be provided at any position on the laminate by applying and drying a barrier coating agent.

[0142] Examples of barrier coating agents include a barrier coating agent (1) containing a vinyl alcohol-based polymer and an aqueous solvent.

[0143] 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.

[0144] As the aqueous solvent, water or the same water-soluble organic solvents exemplified for use in preparing coating agents used for forming the release layer can be used. The aqueous solvent can be used alone or in combination of two or more types.

[0145] The barrier coating agent (1) may further contain additives such as a layered inorganic compound, a crosslinking agent capable of reacting with the functional groups of the vinyl alcohol-based polymer, an adhesion improver, an inorganic filler, an antifoaming agent, stabilizers (such as antioxidants, heat stabilizers, ultraviolet absorbers, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, a leveling agent, etc.

[0146] Commercially available products can also be used as the barrier coating agent (1). Examples include Excevia (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., SunBar (registered trademark) series manufactured by Sankyo Chemical Co., Ltd., Take lac WPB (registered trademark) series manufactured by Mitsui Chemicals, Inc., LG-OX manufactured by Tokyo Ink Co., Ltd., and the like.

[0147] Examples of the barrier coating agent include a gas barrier coating agent (2) containing at least one kind of a water-soluble polymer having a hydroxyl group and a silicon compound represented by Si(OR 1 )4 or R 2 Si(OR 3 )3 (where OR 1 and OR 3 represent hydrolyzable groups and R 2 represents an organic functional group), or a hydrolyzate of the silicon compound.

[0148] Examples of the water-soluble polymer having a hydroxyl group include vinyl alcohol-based polymers, polyvinylpyrrolidone, starch, methylcellulose, carboxymethylcellulose, sodium alginate, and the like.

[0149] Examples of the silicon compound or the hydrolyzate of the silicon compound include tetraalkoxysilanes such as tetraethyl silicate (Si(OC2H5)4) (hereinafter sometimes referred to as TEOS), tetramethyl silicate; trialkoxysilanes such as trimethoxy methyl silane, triethoxy methyl silane, trimethoxy vinyl silane; dialkoxysilanes such as dimethoxy dimethyl silane, diethoxy dimethyl silane; monoalkoxysilanes such as methoxy trimethyl silane, ethoxy trimethyl silane, or their hydrolyzates or partial hydrolyzates.

[0150] 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.

[0151] 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).

[0152] 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).

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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).

[0169] 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.

[0170] 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.

[0171] (Heat-resistant coating layer) The laminate used in 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, and can be provided at any position on the laminate by applying and drying a heat-resistant coating agent.

[0172] To illustrate with an example where a laminate is used as a component for packaging materials to wrap its 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 it will shrink due to heat when the laminate is formed into a bag by heat sealing. Such problems can be suppressed by providing a heat-resistant coating layer. It is preferable that the heat-resistant coating layer be positioned outside the base material that is the outermost of the base materials constituting the laminate when the bag is formed, as viewed from the contents. For example, if the first base material is the outermost base material among the base materials constituting the laminate of the present invention, it is preferable that the heat-resistant coating layer be provided on the side of the first base material opposite to the adhesive layer.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] (packaging material) Packaging materials obtained by overlapping the aforementioned laminates with heat-seal layers facing each other and then heat-sealing the peripheral edges can also be used as recycled materials. Methods for making the bags include folding the laminates or overlapping them so that the inner layers (sealant film surfaces) face each other, and then heat-sealing the peripheral edges in various forms, such as side seals, two-sided seals, three-sided seals, four-sided seals, envelope seals, gusset seals, pleated seals, flat-bottom seals, square-bottom seals, gusset seals, and other heat-seal types. Packaging materials can take various forms depending on the contents, usage environment, and usage. Standing pouches are also possible. Heat sealing can be carried out using known methods such as bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

[0182] Products using the packaging material are manufactured by filling the contents into the packaging material 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, zosui, porridge, 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 butter, salads, frozen vegetables, and processed potato products; processed livestock products such as ham, bacon, sausages, processed chicken products, and corned beef; fish ham / sausages, processed seafood products, kamaboko, nori, and tsukudani. Examples of recyclable materials include processed seafood products such as boiled fish, dried bonito flakes, salted seafood, smoked salmon, and 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, dumplings, and croquettes; dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula; liquid seasonings; retort curry and pet food; and pharmaceuticals such as cigarettes, disposable hand warmers, and intravenous fluid packs, as well as cosmetics and vacuum insulation materials. Packaging materials that have finished their role in protecting the contents of these items can also be used as recycled materials.

[0183] <Method for manufacturing recycled plastics> Next, the method for producing recycled plastics according to the present invention will be described. The method for producing recycled plastics according to the present invention includes the steps of peeling the recycled material (the laminate and packaging material described above) into individual base materials (peeling step), separating them according to resin type (separation and collection step), melting and kneading each, and then pelletizing them.

[0184] (Peeling process) In the stripping process, the recycled material is immersed in a stripping agent for a certain period of time, which allows the adhesive and printing ink to be removed from the substrate and separated into a single-layer film. Examples of stripping agents include aqueous solutions of basic compounds. The stripping agent may further contain hydrophilic alcohol, surfactants, defoamers, and other additives.

[0185] When using a film with a metal or metal oxide vapor-deposited layer as the 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] Examples of surfactants include anionic surfactants such as alkylbenzene sulfonates, alkylphenyl sulfonates, alkylnaphthalene sulfonates, higher fatty acid salts, sulfate salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates.

[0190] Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylolamides, alkyl alkanolamides, acetylene glycols, oxyethylene adducts of acetylene glycols, polyethylene glycol, polypropylene glycol block copolymers, etc.

[0191] Cationic surfactants such as alkyltrimethylammonium salts, alkylPG trimethylammonium salts, alkyldimethylbenzylammonium salts, alkylamidoamines, alkylPG dimethylamines, and cationic polymers.

[0192] Alkyl betaine, alkylamide betaine, imidazolinium betaine, amphoteric surfactants such as amine oxide,

[0193] Silicone-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers. Examples include biosurfactants such as spicrispolic acid, rhamnolipid, and lysolecithin.

[0194] These surfactants can be used individually or in combination of two or more types. When surfactants are added, the amount added is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and even more preferably 0.01 to 1% by mass, relative to the total amount of the stripping agent.

[0195] Examples of defoaming agents include water-soluble organic solvents and nonionic surfactants with an HLB value in the range of 1 to 3, which can be used individually or in combination of two or more. Silicone compounds, especially emulsion-type or self-emulsifying silicone compounds, are preferred. When adding a defoaming agent, the amount added is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and even more preferably 0.01 to 1% by mass, relative to the total amount of the release agent.

[0196] 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.

[0197] The peeling of the recycled 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.

[0198] When immersing the laminated film in the release agent, it is preferable that the release agent is agitated. Examples of agitation methods include mechanically agitating the dispersion of laminated film contained in the treatment tank with agitator blades, agitating with a water flow 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 recycled material.

[0199] 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.

[0200] (Separation and collection process) The release agent after the release process contains adhesives and printing inks removed from the recycled material, film fragments (first substrate, second substrate, etc.) that have separated from the recycled material due to the release of the adhesive, and (if the recycled material contained a metal layer or metal vapor-deposited layer) metal fragments floating or dissolved in it. In the sorting and collection process, these are removed from the release agent, sorted, and collected.

[0201] 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.

[0202] (Reuse of release agent) The release agent used in the peeling process of recycled materials 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 from the recycled material. One method for removing components other than film fragments is filtration.

[0203] (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 rotation speed of the screw during kneading can be appropriately adjusted depending on the equipment used for pelletization, the shape of the screw in that equipment, and the gap between the screws (in the case of a twin-screw system), but one example is 50-1000 RPM.

[0204] 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.

[0205] The recycled plastic obtained by the method for producing recycled plastic of the present invention (hereinafter also referred to as 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; hindered amine-based weather stabilizers; waxes with an acid value of 5 mg KOH / g or less; at least one antistatic agent selected from the group consisting of fatty acid sulfonates and fatty acid esters; heat stabilizers, nucleating agents, antiblocking agents, mold release agents, ultraviolet absorbers, colorants, biodegradability-imparting agents, and the like.

[0206] The recycled plastic of the present invention may contain virgin plastic as a raw material in addition to the recycled material described above. 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).

[0207] (Crushing process) Prior to the step of immersing the recycled material in a release agent, a crushing step of the recycled material may be provided. This increases the surface area of ​​the recycled material that comes into contact with the release agent, thereby shortening the peeling time of the recycled material. On the other hand, the separated recycled material can then be separated by specific gravity separation 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 recycled material 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.

[0208] 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.

[0209] 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.

[0210] (Washing process) It is preferable that the crushed recycled material pieces undergo a washing process before being sent to the peeling process. In the washing process, the materials are placed in a washing container containing a washing solution such as water or a detergent solution, and stirred in the container to wash away organic matter (food residue, grease, etc.) and inorganic matter (sand, dust, etc.) attached to the recycled material. Next, the recycled material pieces are transferred to a rinsing container containing rinsing water, rinsed, and then drained.

[0211] <Molded products made from recycled plastic> 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, automobile parts such as bumpers and interior materials, components for home appliances, containers such as pallets and containers for transport, bottles, hangers, stationery, pots and cups, disposable cutlery, and toys. It can also be recycled as a film, or the recycled film can be molded and used as cushioning material when transporting fruits, etc., but is not limited to these uses. As a method for turning the recycled plastic of the present invention into a film to make a recycled film, known methods such as T-die molding, inflation molding, solution casting molding, and calendering can be used. As a method for molding the recycled film, known methods such as vacuum forming and hot press molding can be used.

[0212] (T-die method) This paper describes an example of a method for manufacturing recycled film using the T-die method or the co-extrusion T-die method. Recycled plastic pellets, and optionally virgin plastic pellets and additives, are mixed in a predetermined ratio, dried, and then supplied to a known melt lamination extruder. In the manufacturing process of this invention, single-screw or twin-screw extruders can be used. Furthermore, to eliminate the pellet drying process, a vacuum line may be provided in the extruder, and a vented extruder can also be used. In addition, for layer B, where the extrusion volume is greatest, a so-called tandem extruder can be used, in which the function of melting the pellets and the function of maintaining the molten pellets at a constant temperature are divided between the extruders.

[0213] The resin, melted and extruded in the extruder, is filtered. Since even very small foreign particles can become large protrusion defects if they enter the film, it is effective to use a high-precision filter that can capture 95% or more of foreign particles, for example, that are 3 μm or larger. Next, the material is extruded into a sheet through a slit-shaped slit die and cooled and solidified on a casting roll to create an unstretched film. If the film has a single-layer structure, a single-layer manifold is used to extrude the sheet from the die. If a laminated structure, such as a three-layer laminated film, is obtained, three extruders and three manifolds or confluence blocks (e.g., confluence blocks with a rectangular confluence section) are used to laminate the material into three layers, and the sheet is extruded from the die (co-extrusion method). The co-extrusion method is preferable because it allows for relatively free adjustment of the thickness ratio of each layer, and it is hygienic and cost-effective in obtaining a multilayer film. On the other hand, when laminating resins with a large difference between their melting point and Tg, the appearance of the film may deteriorate or it may become difficult to form a uniform layer structure during co-extrusion. To suppress such deterioration, the T-die chill-roll method, which allows for melt extrusion at relatively high temperatures, is preferred.

[0214] The sheet extruded from the die is cooled on a casting roll to produce an unstretched film. When stretching the obtained unstretched film, the film, which has been cooled in close contact with the casting roll, is separated from the casting roll using a separation roll and guided to the next stretching process. The stretching method may be simultaneous biaxial stretching or sequential biaxial stretching. When manufacturing a film using sequential stretching, the initial longitudinal stretching is important for suppressing the occurrence of defects and thickness unevenness in the longitudinal direction, and the stretching temperature is 45°C to 180°C, preferably 80°C to 170°C. If the stretching temperature is lower than 45°C, the film is prone to tearing, and if the stretching temperature is higher than 180°C, the film surface is prone to thermal damage. Furthermore, from the viewpoint of preventing uneven stretching and scratches, it is preferable to perform stretching in two or more stages, with a total stretching ratio of 1.1 to 5.0 times, preferably 3.0 to 4.0 times, in the length direction, and 1.1 to 7.0 times, preferably 3.0 to 5.0 times, in the width direction. When setting the longitudinal stretching ratio to the aforementioned values, it is desirable to set multiple stretching sections to make it less likely for the stretching roll and film to slip, in order to suppress fluctuations in stretching tension due to slippage.

[0215] In sequential stretching, the longitudinal stretching process is prone to damage when the film slips due to the difference in peripheral speed between the roll and the film during contact between the film and the roll, and can also cause uneven thickness in the longitudinal direction. Therefore, a drive system that allows the peripheral speed of each roll to be set individually is preferred. In the longitudinal stretching process, the material of the transport roll is selected by either heating the unstretched film to above its glass transition point before stretching, or transporting it to the stretching zone while maintaining a temperature below the glass transition point and then heating it all at once during stretching. When heating the unstretched film to above its glass transition point before stretching, adhesion due to heating can induce uneven stretching. To prevent this, it is preferable to select from non-stick silicone rolls, ceramics, or Teflon®. Furthermore, the stretching roll is the step in the process where the film is subjected to the most stress, and is prone to stretching irregularities that cause scratches and thickness variations in the longitudinal direction. Therefore, the surface roughness Ra of the stretching roll is preferably 0.005 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.6 μm or less. If Ra is greater than 1.0 μm, the irregularities on the roll surface during stretching are more likely to be transferred to the film surface, while if it is less than 0.005 μm, the roll and the film surface will adhere, making the film more susceptible to thermal damage. To control surface roughness, it is effective to appropriately adjust the particle size of the abrasive, the number of polishing cycles, etc.

[0216] In sequential stretching, setting the longitudinal stretching ratio lower than the transverse stretching ratio is a preferable stretching condition for reducing thickness unevenness in the longitudinal direction.

[0217] Next, the unstretched film is transported to the stretching zone while being kept at a temperature below the glass transition point. When heating the film all at once during stretching, it is preferable to use metal rolls with a surface roughness Ra of 0.2 μm to 0.6 μm, which have been surface-treated with hard chromium or tungsten carbide, for the transport rolls in the preheating zone, in order to suppress adhesion that can cause heat wrinkles.

[0218] Next, the uniaxially oriented film, which has been stretched in the longitudinal direction, is stretched in the width direction using a transverse stretcher to produce a biaxially oriented (biaxially oriented) film. This transverse stretcher uses self-circulation in each oven chamber to blow hot air onto the film, thereby raising the film's temperature and performing stretching and heat fixing. At this time, in order to prevent oligomers and volatile components precipitated from the heat-treated film in the oven from cooling and adhering to the oven, it is advisable to supply and exhaust air into the oven to replace the air. When the air supplied into the oven merges with the circulating air, if the air temperature remains close to that of the outside air, temperature unevenness may occur in the air after merging, potentially worsening the thickness unevenness in the longitudinal and width directions. Therefore, it is preferable to heat the supplied air to the same temperature as the circulating air, or to a temperature commensurate with the capacity of the heat exchanger that heats the circulating air.

[0219] The stretching process may involve re-stretching once or more in each direction, or simultaneous re-stretching in two axes. One method to suppress thickness unevenness in the longitudinal direction is to alleviate the bowing that occurred in the previous transverse stretching process during the longitudinal re-stretching process. In this case, the transport rolls may be heated before the longitudinal re-stretching, or unheated rolls may be used for transport. Furthermore, the film may pass through the longitudinal re-stretching process without applying a stretching ratio. After the longitudinal re-stretching, transverse stretching is performed, and the film is heat-treated after stretching. This heat treatment can be carried out in an oven, on heated rolls, or any other conventionally known method. The heat treatment temperature can usually be any temperature between 70°C and 180°C, and the heat treatment time is usually preferably between 1 second and 60 seconds. The heat treatment may be carried out while relaxing the film in its longitudinal and / or width directions.

[0220] After heat treatment, the film can be modified by, for example, providing an intermediate cooling zone or a slow cooling zone to adjust its dimensional change rate and flatness. In particular, to impart a specific thermal shrinkage property, the film may be relaxed in the longitudinal and / or transverse directions during or after the heat treatment in the intermediate cooling zone or slow cooling zone.

[0221] After biaxial stretching, the film is cooled in a conveying process, then the edges are cut and the film is wound to obtain an intermediate product. During this conveying process, the film thickness in the width direction is measured, and this data is used as feedback to adjust the film thickness by adjusting the die thickness, etc., and foreign matter can also be detected using a defect detector.

[0222] The thickness of the resulting film is preferably 5 to 300 μm, and more preferably 10 to 200 μm, when a single-layer film is obtained. Furthermore, when a film with a three-layer laminated structure is obtained by co-extrusion, for example, the thickness of each layer is preferably 1 to 200 μm, and more preferably 2 to 150 μm. The total film thickness is preferably 5 to 300 μm, and more preferably 10 to 200 μm.

[0223] (Inflation method) This paper describes an example of a method for manufacturing recycled film using the inflation method. In the specifications and molding conditions of the inflation molding machine, for example, the diameter of the extruder is 10 to 600 mm, preferably 20 to 300 mm, and more preferably 25 to 200 mm, and the ratio L / D of the diameter D to the length L from the bottom of the hopper to the tip of the cylinder is 8 to 45, preferably 12 to 36.

[0224] The die has a shape commonly used in inflation molding, such as a spider type, spiral type, or stacking type flow path, and its diameter is 1 to 5000 mm, preferably 5 to 3000 mm, and more preferably 10 to 1800 mm. The bubble can be cooled using a commonly used air ring, and the cooling gas can be any known type. Furthermore, its temperature can be cooled by a chiller or heated by a heater. In addition, known methods can be used to cool the bubble, such as blowing cooling air from an external air ring or circulating cooling gas inside. The shape and number of air rings are not limited, and one or more of known types, such as single-slit, dual-slit, or chambered types, can be provided.

[0225] The molding conditions are as follows: the resin extruded from the die has a temperature in the range of 140 to 270°C, preferably 180 to 250°C; the average extrusion rate, determined by the extrusion rate and die shape, is 1 mm / min to 10 m / min, preferably 5 mm / min to 5 m / min, and more preferably 10 mm / min to 1 m / min. The bubbles exiting the die are expanded by the internal gas, and the blow ratio, expressed as the ratio of the bubble diameter to the die bore diameter, is in the range of 1.0 to 4.5, preferably 1.5 to 3.5; and the TUR, expressed as the ratio of the take-up rate to the average flow velocity when extruded from the die, is in the range of 2.0 to 200, preferably 10 to 100. These bubbles are cooled and solidified, and the frost line height from the die exit to the solidification of the bubbles varies depending on the film formation rate and film thickness, but is in the range of 5 to 1800 mm, preferably 10 to 1200 mm, and more preferably 20 to 800 mm. The thickness of the resulting film is preferably 5 to 300 μm, and more preferably 10 to 200 μm, when a single-layer film is obtained. Furthermore, when a film with a three-layer laminated structure is obtained by co-extrusion, for example, the thickness of each layer is preferably 1 to 200 μm, and more preferably 2 to 150 μm. The total film thickness is preferably 5 to 300 μm, and more preferably 10 to 200 μm.

[0226] When pre-kneading is necessary to obtain the recycled film of the present invention, known equipment commonly used for thermoplastic resins can be used.

[0227] (calendering method) This paper describes one example of a method for producing recycled film using the calendering process. The preferred temperature setting for the calendering apparatus during molding is 80 to 180°C, and more preferably 90 to 170°C. If the temperature is below 80°C, the sheet may harden during processing, resulting in no sheet being obtained, or even if a sheet is obtained, it may have many flow marks and bank marks, resulting in an inferior appearance. On the other hand, if the temperature exceeds 180°C, the viscosity during melting is low and the fluidity is high, which may make processing difficult and may also cause thermal degradation.

[0228] The rotation speed of the calender roll is preferably 5 to 60 m / min, and more preferably 10 to 50 m / min. If the calender roll rotation speed is less than 5 m / min, air in the molten material will not escape easily, resulting in defects on the sheet or film surface. Also, if the calender roll rotation speed is faster than 60 m / min, the material may not be able to be picked up.

[0229] After biaxial stretching deformation of recycled plastic using a calendering or roll forming machine, further thin sheets or films can be efficiently produced by melt-stretching in at least one direction in the next step. Here, melt-stretching refers to stretching the recycled plastic while it is molten. The stretching ratio when melt-stretching is preferably 120-500%, more preferably 130-400%, and even more preferably 150-350%. If a sheet or film is produced with a stretching ratio of less than 120%, the improvement in production efficiency due to melt-stretching is minimal, and if a sheet or film is produced with a stretching ratio of 500% or more, stretching inconsistencies may occur, making it difficult to obtain a sheet or film of uniform thickness. Here, the stretching ratio when melt-stretching refers to 100 × [thickness of the sheet or film before melt-stretching] / [thickness of the sheet or film after melt-stretching].

[0230] The resulting recycled film is preferably subjected to biaxial stretching deformation of the recycled plastic, melt-stretched as necessary, and then cooled in contact with a drum or the like. The set temperature of the cooling drum is preferably 0 to 120°C, more preferably 20 to 100°C. At temperatures higher than 120°C, cooling is insufficient, making it difficult to take the film back after molding, and the resulting recycled film may deform. Furthermore, temperatures lower than 0°C are not economical because they require refrigerants or the like.

[0231] The thickness of the obtained recycled film is not particularly limited, but is preferably less than 1.0 mm, more preferably 0.50 mm or less, and even more preferably 0.30 mm or less. If the thickness of the sheet or film is 1 mm or more, the surface smoothness of the sheet or film may be poor. When obtaining a sheet or film with a thickness of 1.0 mm or more, it is preferable to manufacture it by laminating multiple sheets or films with a thickness of less than 1.00 mm. On the other hand, the lower limit of the thickness depends on the molding apparatus, but considering processability and thickness uniformity, it is preferably 0.03 mm or more, and more preferably 0.05 mm or more.

[0232] By combining these methods, it is possible to obtain a plastic film having, for example, the following laminated structure. (1) A recycled film having at least two resin layers (A) and (B) made from recycled plastic. (2) A recycled film having at least a resin layer (A), a resin layer (B), and a resin (C) made from recycled plastic.

[0233] In the case of (1), it is preferable to have a step of heating and melting each of the resin mixture (A) containing 0.1 to 99% by mass of recycled plastic and 99.9 to 1% by mass of virgin resin derived from petroleum or biomass of the same type as the recycled plastic, and resin mixture (B) in an extruder, a step of laminating (A) / (B) in the molten state, and a step of forming a film using one of the T-die method, inflation method, or calendering method, and it is preferable to use the co-extrusion method in the lamination step.

[0234] In the case of (2), it is preferable to have a step of heating and melting each of the resin mixture (A), resin mixture (B), and resin mixture (C) containing 0.1 to 99% by mass of recycled plastic and 99.9 to 1% by mass of virgin resin derived from petroleum or biomass in a separate extruder, a step of laminating (A), (B), and (C) in the molten state, and a step of forming a film using one of the T-die method, inflation method, or calendering method, and it is preferable to use the co-extrusion method in the lamination step. Furthermore, in the process of stacking (A), (B), and (C) in a molten state, the stacking order is not particularly limited; they may be stacked in the order of (A) / (B) / (C), (A) / (C) / (B), (B) / (A) / (C), or (B) / (C) / (A).

[0235] Resin mixture (B) and resin mixture (C) may consist solely of virgin resins derived from petroleum or biomass, or they may contain virgin resins derived from petroleum or biomass and recycled plastics. In the case of a resin mixture containing virgin resins derived from petroleum or biomass and recycled plastics, it is preferable that the recycled plastics make up 0.1 to 99% by mass and the virgin resins derived from petroleum or biomass make up 99.9 to 1% by mass.

[0236] Furthermore, resin mixture (B) and resin mixture (C) may contain known additives. Components such as antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, mold release agents, ultraviolet absorbers, colorants, and biodegradability-granting agents can be added to the extent that they do not impair the purpose of the present invention, and are not particularly limited; commercially available products can also be used.

[0237] In the case of (2), in a plastic film having at least a resin layer (A), a resin layer (B), and a resin (C) made from recycled plastic, it is preferable that the resulting plastic film has better film properties by having at least a resin layer (A) made from recycled plastic on the inside of the laminated structure. The recycled film of the present invention is a film that is suitable for practical use as there is little risk of holes or tears occurring during the series of processes in film molding, but in applications where higher strength is desired during distribution, such as lid material, a plastic film with even greater strength can be obtained if the outermost layer structure during distribution is a resin mixture (B) or resin mixture (C) made from virgin resin derived from petroleum or biomass.

[0238] Specifically, a resin mixture (B) consisting of virgin resin derived from petroleum or biomass / a resin mixture (A) containing 0.1 to 99% by mass of the recycled plastic and 99.9 to 1% by mass of virgin resin derived from petroleum or biomass / a resin mixture (C) consisting of virgin resin derived from petroleum or biomass, Alternatively, it is preferable that the resin mixture (B) contains 0.1 to 99% by mass of recycled plastic and 99.9 to 1% by mass of virgin resin derived from petroleum or biomass; (A) contains 0.1 to 99% by mass of recycled plastic and 99.9 to 1% by mass of virgin resin derived from petroleum or biomass; or (C) is a resin mixture consisting of virgin resin derived from petroleum or biomass.

[0239] The resulting plastic film surface may be subjected to various surface treatments, such as flame treatment or corona discharge treatment, as necessary, to ensure that an adhesive layer free from defects such as film breakage or repulsion is formed.

[0240] Since the recycled film of the present invention is obtained as a substantially unstretched multilayer film by the above manufacturing method, secondary molding such as deep drawing by vacuum forming and embossing is possible. Furthermore, embossing may be performed immediately after molding by contacting the film with a roll having an uneven surface.

[0241] (Laminates and packaging materials made from recycled film) The recycled film of the present invention can be laminated by bonding it with a separate base film or by other means to form a laminate. The structure of the laminate can be the same as that of the laminate used in the recycling method of the present invention. If the recycled film of the present invention is made into a laminate with a structure similar to that of the laminate used in the recycled plastic, which is the raw material of the present invention, it will be able to withstand repeated recycling.

[0242] The laminate using the recycled film of the present invention can be used as packaging material. The bag-making method and applications (contents) of the packaging material can be the same as those used for the packaging material in the recycling method of the present invention. In order to reduce the initial tear strength and improve ease of opening, it is preferable to form arbitrary tear-initiating sections such as V-notches, I-notches, perforations, or micropores in the sealing portion of the packaging material.

[0243] (Molded body) The recycled film of the present invention can also be used as a vacuum-formed molded body. The vacuum forming method is not particularly limited, and the following methods can be used, but are not limited thereto. • Heated pressure air molding method: A method in which battery packaging material is sandwiched between a lower mold having holes for supplying high-temperature, high-pressure air and an upper mold having a pocket-shaped recess, and the recess is formed by supplying air while heating and softening the material. • Preheater flat plate compressed air molding method: A method in which battery packaging material is heated and softened, then sandwiched between a lower mold having holes for supplying high-pressure air and an upper mold having pocket-shaped recesses, and the recesses are formed by supplying air. • Drum-type vacuum forming method: A method in which battery packaging material is partially heated and softened in a heated drum, and then the recesses of a drum having pocket-shaped recesses are vacuumed to form the recesses. • Pin molding method: A method in which the bottom material sheet is heated and softened, and then pressed into place using a mold with pocket-shaped indentations and recesses. • Preheater plug-assisted compressed air molding method: A method in which battery packaging material is heated and softened, then sandwiched between a lower mold having holes for supplying high-pressure air and an upper mold having a pocket-shaped recess, and the recess is formed by supplying air, and a convex-shaped plug is raised and lowered during molding to assist the molding process.

[0244] The surface temperature of the plastic film during vacuum forming is typically in the range of 150 to 250°C, but preferably in the range of 160 to 220°C, and more preferably in the range of 160 to 200°C. When the surface temperature is within the above range, the drawdown properties and shapeability are good, and the wall thickness becomes uniform.

[0245] The recycled film of the present invention can be recycled again using the recycling method of the present invention and used as recycled plastic. [Examples]

[0246] 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.

[0247] <Preparation of adhesive> (Preparation of adhesives 1-4) (Polyol composition 1) In a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, and moisture separator, 105 parts terephthalic acid, 105 parts isophthalic acid, 53.83 parts dimer acid (Tsunodyme 216, manufactured by Tsukuno Oleochemicals Co., Ltd., AN=194 mgKOH / g), 103.26 parts adipic acid, 48.94 parts ethylene glycol, 98.12 parts neopentyl glycol, 48.94 parts 1,6-hexanediol, and 0.15 parts titanium tetraisopropoxide (hereinafter abbreviated as TIPT) 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. When the acid value reached 1.5 mgKOH / g, the pressure was reduced to 10 mmHg or less and held for 1.5 hours to complete the esterification reaction and obtain an intermediate polyester polyol.

[0248] 100 parts of the intermediate polyester polyol, which had been heated to 100°C, were charged into a reactor equipped with a condenser and diluted and dissolved with 43 parts of ethyl acetate. Then, at 80°C, 3.2 parts of isophorone diisocyanate and 0.02 parts of iron neodecanoate were added, and the urethane reaction was carried out until the NCO content was 0.01% or less as measured by NCO. After that, the solution was further diluted with ethyl acetate until the non-volatile content was 50.0%, and a polyester urethane polyol solution with a Gardner viscosity of (WY) at this point was obtained. This was designated as polyol composition 1.

[0249] (Polyisocyanate composition 1) As polyisocyanate composition 1, a biuret form of hexamethylene diisocyanate (manufactured by Asahi Kasei Corporation, Duranate 24A-100, 100% non-volatile content) was used.

[0250] (Polyisocyanate composition 2) As polyisocyanate composition 2, a mixture of 40 parts of biuret hexamethylene diisocyanate (manufactured by Asahi Kasei Corporation, Duranate 24A-100, 100% non-volatile content), 40 parts of trimethylolpropane adduct toluene diisocyanate (manufactured by Covestro, Desmodule L75, 75% non-volatile content), and 20 parts of carbodiimide-modified diphenylmethane diisocyanate (manufactured by BASF INOAC Polyurethanes, Luplanate MM-103B, 100% non-volatile content) was used.

[0251] (Polyisocyanate composition 3) As the polyisocyanate composition 3, a trimethylolpropane adduct of toluene diisocyanate (manufactured by Covestro, Desmodule L75, non-volatile content 75%) was used.

[0252] (Polyisocyanate composition 4) As polyisocyanate composition 4, a mixture of 80 parts of xylene diisocyanate trimethylolpropane adduct (manufactured by Mitsui Chemicals, Inc., Takenate D-110N, non-volatile content 75%) and 20 parts of isophorone diisocyanate nurate (manufactured by Evonik Japan, Vestanate T-1890, non-volatile content 100%) was used.

[0253] (Adhesive 1) Adhesive 1 was prepared by blending polyol composition 1 and polyisocyanate composition 1 so that the [NCO] / [OH] ratio was 1.0. (Adhesive 2) Adhesive 1 was prepared by blending polyol composition 1 and polyisocyanate composition 2 so that the [NCO] / [OH] ratio was 1.0. (Adhesive 3) Adhesive 3 was prepared by blending polyol composition 1 and polyisocyanate composition 3 so that the [NCO] / [OH] ratio was 1.0. (Adhesive 4) Adhesive 4 was prepared by blending polyol composition 1 and polyisocyanate composition 4 so that the [NCO] / [OH] ratio was 1.0.

[0254] (Preparation of Adhesives 5 - 7) (Polyol Composition 2)) Into a polyester reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, etc., 31.4 parts of diethylene glycol, 9.6 parts of glycerin, 19.9 parts of isophthalic acid, 39.1 parts of adipic acid, and 0.01 part of titanium tetraisopropoxide were added, and an ester reaction was carried out at an internal temperature of 220 °C. After the dehydration reaction, a polyester polyol with an acid value of 1.5 mgKOH / g was obtained. 20 parts of polypropylene triol (Excenol 430 manufactured by AGC, molecular weight 400, trifunctional, hydroxyl value 400 mgKOH / g) was added to 80 parts of this polyester polyol to obtain Polyol Composition 2.

[0255] (Polyol Composition 3) Into a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, water separator, etc., 400 parts by mass of propylene glycol, 80 parts by mass of trimethylolpropane, 700 parts by mass of adipic acid, and 0.1 part by mass of titanium tetraisopropoxide were charged under nitrogen gas introduction, and the mixture was gradually heated so that the temperature at the upper part of the rectification tube did not exceed 100 °C, and the internal temperature was maintained at 250 °C. The esterification reaction was terminated when the acid value reached 1 mgKOH / g or less to obtain a polyester polyol. The hydroxyl value of the polyester polyol was 185 mgKOH / g. 6% by mass of amine - initiated polypropylene polyol (EDP - 450 manufactured by ADEKA, molecular weight 450, hydroxyl value 505 mgKOH / g) was added to this polyester polyol to obtain Polyol Composition 3. The hydroxyl value of Polyol Composition 3 was 220 mgKOH / g.

[0256] (Polyisocyanate Composition 5) In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, and a condenser, 774.5 parts of toluene diisocyanate (TDI) were added, and the mixture was heated to 40 °C while stirring under a nitrogen gas stream. Then, 225.5 parts of a bifunctional polyethylene glycol with a molecular weight of 200 were added while paying attention to heat generation, and then the mixture was heated to 60 °C. Further, the reaction was continued at 60 °C until the NCO% no longer changed, and 1.0 part of polyphosphoric acid was added to terminate the reaction. Next, using a thin-film distillation apparatus, at a pressure of about 0.02 Torr and a temperature of 160 °C, the reaction product of TDI in the urethane prepolymer was purified until the TDI content in the solid content reached 0.05% by mass, and a polyurethane polyisocyanate with an NCO% of 14.5% was obtained.

[0257] A mixture of 90 parts of the synthesized polyurethane polyisocyanate and 10 parts of a urethane of hexamethylene diisocyanate (Desmodur N3300, manufactured by Covestro, non-volatile content 100%) was used as the polyisocyanate composition 5.

[0258] (Polyisocyanate composition 6) Into a flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a rectification tube, a water separator, etc., 7 parts of ethylene glycol and 35 parts of diethylene glycol were charged, and the mixture was heated to 80 °C while stirring under a nitrogen gas stream. While further stirring, 36 parts of adipic acid and 22 parts of isophthalic acid were charged into the reaction vessel, and the internal temperature was maintained at 250 °C by gradually heating so that the temperature at the upper part of the rectification tube did not exceed 100 °C, and an esterification reaction was carried out. When the acid value reached 12.0 mgKOH / g or less, the temperature was set to 240 °C, the inside of the reaction vessel was gradually depressurized, and the reaction was carried out at 40 Torr or less to obtain a polyester polyol having hydroxyl groups at both ends with an acid value of 1.0 mgKOH / g and a hydroxyl value of 84 mgKOH / g.

[0259] In a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, and condenser, 342.8 parts of toluene diisocyanate (TDI) were added and heated to 40°C while stirring under a nitrogen gas stream. Then, 657.2 parts of the polyester polyol synthesized above were added carefully, taking care to avoid exothermic reactions, and the mixture was heated to 60°C. The reaction was continued at 60°C until the NCO% no longer changed, and 1.0 part of polyphosphate was added to terminate the reaction. Next, using a thin-film distillation apparatus, the TDI in the urethane prepolymer, which was the reaction product of TDI, was purified to 0.05% by mass of the solid content at a pressure of approximately 0.02 Torr and a temperature of 160°C until the TDI content was 0.05% by mass of the solid content, thereby obtaining a polyurethane polyisocyanate with an NCO% of 4.8%.

[0260] Polyisocyanate composition 6 was prepared by mixing 90 parts of synthesized polyurethane polyisocyanate with 10 parts of hexamethylene diisocyanate nurate (manufactured by Covestro, Desmodulo N3300, 100% non-volatile content).

[0261] (Polyisocyanate composition 7) 582.2 parts of toluene diisocyanate (TDI) were added to a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, and condenser, and heated to 40°C while stirring under a nitrogen gas stream. Then, 278.5 parts of bifunctional polyethylene glycol with a molecular weight of 400 and 139.3 parts of bifunctional polypropylene glycol with a molecular weight of 1000 were added, taking care to avoid exothermic reactions, and the mixture was then heated to 60°C. The reaction was continued at 60°C until the NCO% no longer changed, and 1.0 part of polyphosphate was added to terminate the reaction. Next, using a thin-film distillation apparatus, the TDI in the urethane prepolymer, which was the reaction product of TDI, was purified to 0.05% by mass of the solid content at a pressure of approximately 0.02 Torr and a temperature of 160°C until the TDI content was 0.05% by mass of the solid content, thereby obtaining NCO% polyurethane polyisocyanate. This was designated as isocyanate composition 7.

[0262] (Adhesive 5) Adhesive 5 was prepared by blending polyol composition 2 and polyisocyanate composition 5 so that the [NCO] / [OH] ratio was 1.0. (Adhesive 6) Adhesive 6 was prepared by blending polyol composition 2 and polyisocyanate composition 6 so that the [NCO] / [OH] ratio was 1.0. (Adhesive 7) Adhesive 7 was prepared by blending polyol composition 3 and polyisocyanate composition 7 so that the [NCO] / [OH] ratio was 1.0.

[0263] (Preparation of adhesives 8-11) (Polyol composition 4) In a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, and moisture separator, 54.0 parts of 3-methylpentanediol, 46.0 parts of isophthalic acid, and 0.01 parts of titanium tetraisopropoxide were charged under nitrogen gas introduction. 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 250°C. The esterification reaction was terminated when the acid value fell to 1 mg KOH / g or less, yielding a polyester polyol with a number average molecular weight of 500 and a hydroxyl value of 224.

[0264] Polyol composition 4 was prepared by mixing 30 parts of the polyester polyol synthesized above, 40 parts of polypropylene glycol (AGC Excenol 420, molecular weight 400, bifunctional, hydroxyl value 280 mg KOH / g), 10.9 parts of polypropylene triol (AGC Excenol 430, molecular weight 400, trifunctional, hydroxyl value 400 mg KOH / g), 17 parts of polyoxypropylene triamine (Huntsman Jeffamine T-403, molecular weight 440, amine value 355 mg KOH / g), 0.1 parts of dibutyltin dilaurelate, 1.0 part of 3-glycidoxypropyltrimethoxysilane, and 1.0 part of 3-aminopropyltriethoxysilane.

[0265] (Polyol composition 5) In a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, rectification tube, and moisture separator, 54.0 parts of 3-methylpentanediol, 30.0 parts of trimethylolpropane, 60.0 parts of adipic acid, and 0.01 parts of titanium tetraisopropoxide were charged under nitrogen gas introduction. 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 220°C. The esterification reaction was terminated when the acid value fell to 1 mg KOH / g or less, yielding a polyester polyol with a number average molecular weight of 500 and a hydroxyl value of 337.

[0266] Polyol composition 5 was prepared by mixing 25 parts of the polyester polyol synthesized above, 13.66 parts of polypropylene triol (Actocol T-1000, manufactured by Mitsui Chemicals, molecular weight 1000, trifunctional), 40 parts of polypropylene glycol (Excenol 420, manufactured by AGC, molecular weight 400, bifunctional, hydroxyl value 280 mg KOH / g), 10 parts of polypropylene polyol (Sannix HD-402, manufactured by Sanyo Chemical Industries, molecular weight 600, tetrafunctional), 9 parts of polyoxypropylene triamine (Jeffermin T-403, manufactured by Huntsman, molecular weight 440, amine value 355 mg KOH / g), 0.9 parts of dimethylolpropionic acid, 0.94 parts of ε-caprolactam, and 0.5 parts of BicatZ.

[0267] (Polyisocyanate composition 8) 150 parts by mass of hexamethylene diisocyanate (HDI) was charged into a flask equipped with a stirrer, thermometer, and nitrogen gas inlet tube, stirred under nitrogen gas, and heated to 60°C. 100 parts by mass of polypropylene glycol with a number average molecular weight of 400 was added dropwise in several portions, and the mixture was stirred for 5-6 hours to complete the urethane formation reaction. Next, using a thin-film distillation apparatus, the HDI in the urethane prepolymer, which is the reaction product of HDI, was purified at a pressure of approximately 0.02 Torr and a temperature of 140°C until the HDI content in the solids was 1% by mass, thereby obtaining polyisocyanate composition 8 with an NCO group content of 9%.

[0268] (Polyisocyanate composition 9) In a flask equipped with a stirrer, thermometer, and nitrogen gas inlet tube, 40.2 parts of 4,4-diphenylmethane diisocyanate and 10.0 parts of hexamethylene diisocyanate nurate were charged into the reaction vessel and stirred under nitrogen gas, and heated to 60°C. To this flask, 37.9 parts of bifunctional polypropylene glycol with a number average molecular weight of 1000 and 2.0 parts of 2,2,4-trimethyl-1,3-pentanediol were added dropwise in several portions, and the mixture was stirred at 80°C for 5-6 hours to carry out the urethane reaction and obtain a polyisocyanate. The obtained polyisocyanate was mixed with 10.0 parts of carbodiimide-modified isocyanate to obtain polyisocyanate composition (X-1).

[0269] (Adhesive 8) Polyol composition 4 and polyisocyanate composition 8 were used in such a ratio that [NCO] / [OH] was 1.3. (Adhesive 9) Polyol composition 5 and polyisocyanate composition 8 were used in such a ratio that [NCO] / [OH] was 1.3. (Adhesive 10) Polyol composition 4 and polyisocyanate composition 9 were used in such a ratio that [NCO] / [OH] was 1.3. (Adhesive 11) Polyol composition 5 and polyisocyanate composition 9 were used in such a ratio that [NCO] / [OH] was 1.3.

[0270] (Preparation of adhesive 12) (Polyol composition 6) Into a polyester reaction vessel equipped with a stirrer, a nitrogen gas introduction pipe, a rectification pipe, a water separator, etc., 1223.3 parts of phthalic anhydride, 255.3 parts of ethylene glycol, 253.2 parts of glycerin and titanium tetraisopropoxide were charged in an amount corresponding to 100 ppm based on the total amount of the polyvalent carboxylic acid and the polyvalent alcohol, and the mixture was gradually heated so that the temperature at the upper part of the rectification pipe did not exceed 100 °C, and the internal temperature was maintained at 220 °C. When the acid value reached 1 mgKOH / g or less, the esterification reaction was terminated, and a polyester polyol having a number average molecular weight of about 650, a hydroxyl value of 261.2 mgKOH / g, and an acid value of 0.8 mgKOH / g was obtained. This was used as the polyol composition 6.

[0271] (Polyisocyanate composition 10) 143 parts of "Takenate D110N (NB)" manufactured by Mitsui Chemicals, Inc. and 24.5 parts of "Takenate 500" manufactured by Mitsui Chemicals, Inc. were mixed to prepare the isocyanate composition 10.

[0272] (Adhesive 12) 70 parts of the polyol composition 6, 167.5 parts of the polyisocyanate composition 10, and 123 parts of ethyl acetate were stirred well to prepare the adhesive 12.

[0273] <Preparation of the release layer coating agent> 10.0 parts of polyvinyl alcohol (manufactured by Mitsubishi Chemical Corporation, Nichigo G-polymer (AZF8035Q)), 1.7 parts of polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin P-1000), 43.3 parts of water, and 45.0 parts of ethanol were mixed to prepare a coating agent for forming the release layer.

[0274] <Manufacture of the laminate> (Laminates 1a to 4a, 12a) To an OPP film (manufactured by Toyobo Co., Ltd., P2161) with a thickness of 20 μm, the adhesive 1 was applied at 3.5 g / m 2 (Solid content), and after drying the solvent with a dryer, it was laminated with a CPP film (manufactured by Toyobo Co., Ltd., P1128) having a thickness of 25 μm. It was aged at 40 °C for 3 days to obtain the OPP / adhesive layer / CPP laminate 1a. Laminates 2a-4a and 12a were obtained in the same manner, except that the adhesives used were changed to adhesives 2-4 and 12.

[0275] (Laminates 1b-4b, 12b) A gravure printing press equipped with a gravure plate with a plate depth of 22 μm applied a coating amount (solid content) of 0.5 g / m² to an OPP film with a thickness of 20 μm (manufactured by Toyobo, P2161). 2 The coating agent was applied in a thick layer, dried by passing it through a 70°C oven, and then left at room temperature for one day to form a desorption layer.

[0276] Next, a urethane-based laminate ink (DIC Corporation, Finart R794 white) was adjusted to 15 seconds (25°C) in a Zaan Cup #3 manufactured by Rigosha, and printed as a solid color onto the desorption layer using a gravure printing press equipped with a gravure plate with a plate depth of 43 μm. The printed layer was then dried or cured by passing it through a 70°C oven.

[0277] Apply adhesive 1 at a rate of 3.5 g / m² to the printed layer. 2 The material was coated with (solids), dried with a dryer, and then laminated with a 25 μm thick CPP film (Toyobo Co., Ltd., P1128). After aging at 40°C for 3 days, a laminate 1b consisting of OPP / desorption layer / printed layer / adhesive layer / CPP was obtained. Laminates 2b-4b and 12b were obtained in the same manner, except that the adhesives used were changed to adhesives 2-4 and 12.

[0278] (Laminated bodies 5a~7a) A 20 μm thick OPP film (Toyobo Co., Ltd., P2161) is coated with adhesive 5 at a rate of 2.0 g / m². 2 The material was coated with (solid content) and laminated with a 25 μm thick CPP film (Toyobo Co., Ltd., P1128). After aging at 40°C for 2 days, a laminate 5a of OPP / adhesive layer / CPP was obtained. Laminates 6a and 7a were obtained in the same manner, except that the adhesives used were changed to adhesives 6 and 7.

[0279] (Laminates 5b-7b) A desorption layer and a printed layer were formed on an OPP film with a thickness of 20 μm (Toyobo Co., Ltd., P2161) in the same manner as in laminate 1b. Laminate 5b consisting of OPP / desorption layer / printed layer / adhesive layer / CPP was obtained in the same manner as above, except that this was used. Laminates 6b and 7b were obtained in the same manner, except that the adhesives used were changed to adhesives 6 and 7.

[0280] (Laminates 8a~11a) Polyisocyanate composition 4 was applied to an OPP film with a thickness of 20 μm (manufactured by Toyobo, P2161), and polyol composition 8 was applied to a CPP film with a thickness of 25 μm (manufactured by Toyobo, P1128), with a total coating amount of polyol composition 4 and polyisocyanate composition 8 of 1.7 g / m². 2 Each layer was applied accordingly, and the polyol composition 4 and the polyisocyanate composition 8 were bonded together so that they were in contact. After aging at 40°C for 2 days, a laminate 8a of OPP / adhesive layer / CPP was obtained. Laminates 9a to 11a were obtained in the same manner, except that the adhesive used was changed to a combination of adhesives 9 to 11.

[0281] (Laminates 8b~11b) A desorption layer and a printed layer were formed on a 20 μm thick OPP film (Toyobo Co., Ltd., P2161) in the same manner as in laminate 1b. Polyisocyanate composition 4 was applied to the printed layer, and polyol composition 8 was applied to a 25 μm thick CPP film (Toyobo Co., Ltd., P1128), with a total coating amount of polyol composition 4 and polyisocyanate composition 8 of 1.7 g / m². 2 Each layer was applied accordingly, and the polyol composition 4 and the polyisocyanate composition 8 were bonded together so that they were in contact. After aging at 40°C for 2 days, a laminate 8b consisting of OPP / desorption layer / printed layer / adhesive layer / CPP was obtained. Laminates 9b to 11b were obtained in the same manner, except that the adhesive used was changed to a combination of adhesives 9 to 11.

[0282] <Laminate delamination> The obtained laminates 1a-12a and 1b-12b were cut into 20mm x 20mm sections to form test specimens 1a-12a and 1b-12b. The specimens were heated to 70°C and immersed in a release agent, and stirred at 400 rpm until the adhesive was completely removed. The release agent used was a mixture of 48 parts water and 50 parts ethanol, with 2 parts sodium hydroxide dissolved in it.

[0283] <Manufacturing of recycled plastics> A mixture of 20 μm thick OPP film (Toyobo Co., Ltd., P2161) and 25 μm thick CPP film (Toyobo Co., Ltd., P1128) in a 40:50 (mass ratio) was similarly pulverized using a pulverizer to obtain a virgin film pulverized mixture.

[0284] Film fragments recovered from the peeling process of test specimen 1a and washed were mixed with a virgin film pulverized mixture in a 50:50 (mass ratio) and fed into the melting and kneading section of a twin-screw extruder (Kobe Steel KTX-30 twin-screw extruder). The melted and kneaded resin was extruded through a 100 μm filter, cooled by immersion in cold water, and then cut with a pelletizer to obtain recycled plastic pellets 1a. The extruder was set to a screw rotation speed of 300 rpm, a temperature of 230 °C, and a discharge rate of 8 kg / h.

[0285] Recycled plastic pellets 2a-12a and 1b-12b were obtained in the same manner, except that film pieces recovered from the peeling process of test piece 1a were replaced with film pieces recovered from the peeling process of test pieces 2a-12a and test pieces 1b-12b and washed.

[0286] <Film Manufacturing> (Film manufacturing method: T-die method) Recycled plastic pellets 1a and Sumitomo Noblen Random FL6737 (manufactured by Sumitomo Chemical Co., Ltd.) pellets were mixed in a 25:75 ratio and fed into the molten section of a T-die extruder (AIKI Riotec T-die film molding unit ALM-TMF200). The molten resin was extruded from the T-die and cooled and solidified with a cooling roll to obtain a 30 μm recycled film 1a. The extruder's screw rotation speed was set to 30 rpm and the temperature to 230°C. A recycled film was obtained in the same manner, except that recycled plastic pellets 2a-12a and 1b-12b were used instead of recycled plastic pellet 1a.

[0287] (Film manufacturing method: Inflation method) Recycled plastic pellets 1a and Sumitomo Noblen Random FL6737 (manufactured by Sumitomo Chemical Co., Ltd.) pellets were mixed in a 25:75 ratio and fed into the molten section of an inflation extruder (AIKI Riotec inflation molding unit ALM-IMF30). The molten resin was extruded from the inflation die and cooled and solidified with air to obtain a recycled film with a thickness of 25 μm. The extruder's screw rotation speed was set to 38 rpm and the temperature to 230°C. A recycled film was obtained in the same manner, except that recycled plastic pellets 2a-12a and 1b-12b were used instead of recycled plastic pellet 1a.

[0288] (Film manufacturing method: Calendering method) Each recycled plastic pellet was mixed with Sumitomo Noblen Random FL6737 (manufactured by Sumitomo Chemical Co., Ltd.) pellets in a 25:75 ratio. The mixture was then formed at 200°C using a calendering machine (inverted L-type calendering machine manufactured by Nippon Roll Co., Ltd.) to produce a 25 μm recycled film. A recycled film was obtained in the same manner, except that recycled plastic pellets 2a-12a and 1b-12b were used instead of recycled plastic pellet 1a.

[0289] (Film manufacturing method: Co-extrusion T-die method, 3 layers) A 25:75 mixture of recycled plastic pellets 1a and Sumitomo Noblen Random FL6737 (manufactured by Sumitomo Chemical Co., Ltd.), and Sumitomo Noblen Random FL6737 (manufactured by Sumitomo Chemical Co., Ltd.) pellets were each fed into the molten section using three extruders and three manifolds. The molten resin was extruded from a T-die and laminated into three layers: virgin olefin resin / recycled plastic pellets and a 25:75 mixture of virgin olefin resin pellets / virgin olefin resin. The layers were then cooled and solidified using a cooling roll to produce recycled films with each layer having a thickness of 10 μm and a total thickness of 30 μm. A recycled film was obtained in the same manner, except that recycled plastic pellets 2a-12a and 1b-12b were used instead of recycled plastic pellet 1a.

Claims

1. A recycling method comprising a peeling step of immersing a laminate, which includes a first substrate, a second substrate, and an adhesive layer for bonding the first substrate and the second substrate, wherein the adhesive layer is a cured coating film of a two-component curing adhesive consisting of a polyol composition and a polyisocyanate composition containing a polyisocyanate compound, in a release agent to separate the first substrate and the second substrate.

2. The recycling method according to claim 1, wherein the release agent is heated to 55°C or higher and 85°C or lower.

3. A separation and recovery step for recovering the first substrate from the peeling agent after the peeling step, The recycling method according to claim 1, further comprising a pelletizing step of melting and kneading the first base material recovered in the separate collection step.

4. The recycling method according to claim 1, 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.

5. The recycling method according to claim 1, wherein the mass ratio of the first substrate to the virgin plastic is 100:0 to 25:

75.

6. Recycled pellets obtained by the recycling method described in claim 5.

7. A plastic product molded from recycled pellets as described in claim 6.

8. A plastic product made from recycled pellets as described in claim 6 and virgin plastic of the same type as the recycled pellets.

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