laminate

Abstract

To provide a laminate in which adhesive strength between an ink layer and an adhesive layer is improved.SOLUTION: A laminate comprising a first plastic film, an ink layer, an adhesive layer, and a second plastic film in this order, wherein the ink layer and the adhesive layer are in contact with each other, the adhesive layer contains a reaction product of polyols having two or more hydroxyl groups and isocyanates having isocyanate groups, the amount of the isocyanate groups is excessive with respect to the amount of the hydroxyl groups, the excessive amount of the isocyanate groups is 0. 1mmol / g or more and 2. 5mmol / g or less in the solid component of the adhesive layer, and the ink layer contains polyurethane resins having amino (- NH2) groups.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminate. [Background technology]

[0002] Gravure inks and flexographic inks are widely used to impart beauty or functionality to printed materials. When printed materials are used as packaging materials, particularly food packaging, they are generally laminated.

[0003] Common lamination structures include dry lamination, lamination structures using adhesives such as non-solvent lamination, and structures using extrusion lamination.

[0004] For example, Patent Document 1 discloses a packaging material having a printed layer containing a polyester-based urethane resin having a specific molecular weight distribution and an adhesive layer containing an isocyanate compound having a specific molecular weight distribution. Also, for example, Patent Document 2 discloses a packaging material having a printed layer containing a polyester-based urethane resin having a specific molecular weight distribution and an adhesive layer containing a polyester resin having a specific molecular weight distribution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-036095 [Patent Document 2] Japanese Patent Publication No. 2023-071162 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a demand for further improvement in adhesive strength between the ink layer and the adhesive layer.

[0007] Therefore, an object of the present invention is to provide a laminate having improved adhesive strength between the ink layer and the adhesive layer. [Means for solving the problem]

[0008] The present invention, in order, a first plastic film; an ink layer; an adhesive layer; a second plastic film; the ink layer and the adhesive layer are in contact with each other, the adhesive layer contains a reaction product of a polyol having two or more hydroxyl groups and an isocyanate having an isocyanate group, the amount of the isocyanate groups is in excess relative to the amount of the hydroxyl groups, the excess amount of the isocyanate group is 0.1 mmol / g or more and 2.5 mmol / g or less in the solid content of the adhesive layer, The ink layer is a laminate containing a polyurethane resin having an amino (—NH2) group, which makes it possible to provide a laminate with improved adhesive strength between the ink layer and the adhesive layer.

[0009] In one embodiment of the laminate of the present invention, the first plastic film and the second plastic film are made of a polyolefin resin.

[0010] In one embodiment of the laminate of the present invention, the ink layer further contains one or more resins selected from the group consisting of cellulose-based resins, polyester resins, acrylic resins, polyamide resins, rosin-modified maleic acid resins, and polyvinyl butyral resins.

[0011] In one embodiment of the laminate of the present invention, the polyurethane resin has an amine value of the solid content of 0.1 mgKOH / g or more and 10 mgKOH / g or less.

[0012] In one embodiment of the laminate of the present invention, a detachable primer layer is further provided on one or both of the surfaces between the first plastic film and the ink layer and the surface between the adhesive layer and the second plastic film. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a laminate having improved adhesive strength between the ink layer and the adhesive layer. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of an example of the laminate of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing a cross section of another example of the laminate of the present invention. [Figure 3] FIG. 3 is a schematic diagram showing a cross section of another example of the laminate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described. These descriptions are for the purpose of illustrating the present invention and are not intended to limit the present invention in any way.

[0016] In the present invention, two or more embodiments can be combined in any manner.

[0017] Unless otherwise specified, the materials, components, compounds, resins, catalysts and organic solvents described in this specification may be used alone or in combination of two or more.

[0018] The accompanying drawings are schematic diagrams given priority for facilitating understanding of the present invention, and therefore the scale and shapes of each layer or member in the drawings are not accurate.

[0019] In the present invention, "ink" refers to a printing ink, such as gravure printing ink or flexographic printing ink, that is applied to a printing method using a printing plate.

[0020] (Laminate) The present invention, in order, a first plastic film; an ink layer; an adhesive layer; a second plastic film; the ink layer and the adhesive layer are in contact with each other, the adhesive layer contains a reaction product of a polyol having two or more hydroxyl groups and an isocyanate having an isocyanate group, the amount of the isocyanate groups is in excess relative to the amount of the hydroxyl groups, the excess amount of the isocyanate group is 0.1 mmol / g or more and 2.5 mmol / g or less in the solid content of the adhesive layer, The ink layer is a laminate containing a polyurethane resin having an amino (—NH2) group.

[0021] Fig. 1 is a schematic diagram showing a cross section of an example of a laminate of the present invention. In the example of Fig. 1, the laminate 1 has, in order, a first plastic film 10, an ink layer 20, an adhesive layer 30, and a second plastic film 40.

[0022] First plastic film Examples of the first plastic film include an OPP film (a polypropylene film, for example, a biaxially oriented polypropylene film), a PET film (a polyethylene terephthalate film, for example, a biaxially oriented polyethylene terephthalate film), and a nylon film. The first plastic film may be coated to improve gas barrier properties and ink receptivity when an ink layer is provided. Examples of commercially available coated first plastic films include a K-OPP film and a K-PET film.

[0023] The thickness of the first plastic film may be adjusted appropriately, and is, for example, 10 to 500 μm.

[0024] Ink layer The ink layer is a layer on which characters, figures, symbols, other desired designs, etc. Examples of inks include gravure printing ink, flexographic printing ink, ultraviolet-curable ink for lithographic offset printing, electron-beam-curable ink for lithographic offset printing, ultraviolet-curable ink for inkjet recording and printing, and electron-beam-curable ink for inkjet recording and printing.

[0025] (Ink) The ink that forms the ink layer contains a polyurethane resin with an amino (-NH2) group, which allows excess isocyanate in the adhesive layer to bond with the amino group in the ink layer, resulting in a laminate with improved adhesive strength between the ink layer and the adhesive layer.

[0026] (Polyurethane resin) The ink contains a polyurethane resin obtained by polymerizing a polyol and a polyisocyanate.

[0027] The amine value of the solid content of the polyurethane resin is greater than 0 mgKOH / g, for example, 0.1 mgKOH / g or more and 10 mgKOH / g or less. The amine value of the solid content of the polyurethane resin is preferably 0.15 mgKOH / g or more, and more preferably 3 mgKOH / g or more. The amine value of the solid content of the polyurethane resin is preferably 9 mgKOH / g or less, and more preferably 5 mgKOH / g or less. By setting the amine value to 0.1 mgKOH / g or more, it is possible to improve the adhesion between an ink layer containing the polyurethane resin and an adjacent layer (e.g., an adhesive layer). Furthermore, by setting the amine value to 10 mgKOH / g or less, the two-component stability of the ink containing the polyurethane resin is excellent.

[0028] In one embodiment, the polyurethane resin has an amino group at its terminal end. In another embodiment, the number of amino groups in the polyurethane resin is 0, 1, 2, 3, 4, 5, or 6. In yet another embodiment, the polyurethane resin has a linear structure and the number of amino groups in the polyurethane resin is 0, 1, or 2.

[0029] Polyol The polyol is preferably a polyester polyol. If necessary, in addition to the polyester polyol, a polyether polyol, a general-purpose polyol, or the like may be used.

[0030] Polyester Polyol The polyester polyol can be obtained by reacting a polycarboxylic acid having two or more carboxyl groups with a polyol having two or more hydroxyl groups.

[0031] Examples of polycarboxylic acids include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, and acid anhydrides thereof; tricarboxylic acids such as trimellitic acid and its anhydrides; benzenetetracarboxylic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, and anhydrides of these acids.

[0032] Plant-derived raw materials can also be used as the polycarboxylic acid. Using plant-derived polycarboxylic acids is preferable because it can increase the biomass content of the ink. Examples of plant-derived polycarboxylic acids include succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, and malic acid.

[0033] Examples of polyols include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-butynediol, and 1,4-butylenediol; 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, and 2-butylenediol; Glycols having a branched structure such as 2-ethyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, and 2-methyl-1,8-octanediol; glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, 1,2,6-hexanetriol, and 1,2,4-butanetriol can be used.

[0034] Plant-derived raw materials can also be used as the polyol. Using a plant-derived polyol is preferable because it can increase the biomass content of the ink. Examples of plant-derived polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, and isosorbide.

[0035] The polyester polyol is preferably contained in the range of 30 to 95% by mass, more preferably 40 to 90% by mass, and most preferably 45 to 85% by mass, based on the total amount of the polyurethane resin.

[0036] The number average molecular weight (Mn) of the polyester polyol is preferably in the range of 400 to 10,000, more preferably in the range of 500 to 7,000, even more preferably in the range of 800 to 6,000, more preferably in the range of 1,000 to 6,000, and even more preferably in the range of 1,500 to 5,500.

[0037] In the present invention, the number average molecular weight (Mn) and weight average molecular weight (Mw) are values ​​measured by gel permeation chromatography (GPC) under the following conditions. (GPC measurement) Measurement equipment: High-speed GPC equipment (Tosoh Corporation "HLC-8220GPC") Columns: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution) Standard sample: A calibration curve was prepared using the following standard polystyrene. [Standard polystyrene] Tosoh Corporation's "TSKgel Standard Polystyrene A-500" Tosoh Corporation's "TSKgel Standard Polystyrene A-1000" Tosoh Corporation's "TSKgel Standard Polystyrene A-2500" Tosoh Corporation's "TSKgel Standard Polystyrene A-5000" "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation Tosoh Corporation's "TSKgel Standard Polystyrene F-2" Tosoh Corporation's "TSKgel Standard Polystyrene F-4" Tosoh Corporation's "TSKgel Standard Polystyrene F-10" Tosoh Corporation's "TSKgel Standard Polystyrene F-20" Tosoh Corporation's "TSKgel Standard Polystyrene F-40" Tosoh Corporation's "TSKgel Standard Polystyrene F-80" Tosoh Corporation's "TSKgel Standard Polystyrene F-128" Tosoh Corporation's "TSKgel Standard Polystyrene F-288" Tosoh Corporation's "TSKgel Standard Polystyrene F-550"

[0038] Polyether polyol The polyurethane resin preferably contains a polyether polyol as a constituent component, and known polyether polyols can be used as the polyether polyol.

[0039] As a constituent component of the polyurethane resin, it is preferable to contain polyether polyol in the range of 1 to 40% by mass relative to the polyurethane resin. It is even more preferable to contain polyether polyol in the range of 1 to 30% by mass relative to the polyurethane resin, and most preferable to contain it in the range of 1 to 20% by mass. When the amount of polyether polyol relative to the polyurethane resin is 1% by mass or more, the polyurethane resin has good solubility in ketone, ester, and alcohol-based solvents, and the resolubility of the ink film in these solvents is unlikely to decrease, resulting in less deterioration of the tone reproducibility of printed matter. Furthermore, when the amount of polyether polyol relative to the polyurethane resin is 40% by mass or less, blocking resistance is unlikely to decrease.

[0040] Furthermore, the Mn of the polyether polyol is preferably 100 to 4,000. When the Mn of the polyether polyol is 100 or more, the polyurethane resin film does not harden and the adhesion to the polyester film is less likely to decrease. When the Mn is 4,000 or less, the polyurethane resin film has sufficient strength and the blocking resistance of the ink layer tends not to decrease.

[0041] Examples of polyether polyols include bifunctional alcohols (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, and 1,4-cyclohexanedimethanol; trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, and pentaerythritol; and bisphenols such as bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F. Examples of polyether polyols include polyether polyols such as polytetramethylene glycol, polypropylene glycol, polyethylene glycol, and polytrimethylene glycol, which are 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 such as glycol or a trifunctional or tetrafunctional aliphatic alcohol; and polyether urethane polyols obtained by further increasing the molecular weight of such polyether polyols with aromatic or aliphatic polyisocyanates.

[0042] General-purpose polyol In synthesizing the polyurethane resin, if necessary, a general-purpose polyol other than the polyester polyol and polyether polyol may be used in combination. As the general-purpose polyol, known polyols can be used.Examples of general-purpose polyols include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; 2-methyl-1,5-pentanediol, 1,2-butanediol, and 1,3-butanediol; Glycols with branched structures such as ethanol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, and 2-methyl-1,8-octanediol; glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, and soybean oil. low molecular weight polyols such as sorbitol; polyether polyols of polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc.; polyester polyols obtained by dehydration condensation or polymerization of low molecular weight polyols with petroleum-derived polycarboxylic acids such as sebacic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, trimellitic acid, and pyromellitic acid, or anhydrides thereof. polyester polyols obtained by ring-opening polymerization of cyclic ester compounds, for example, lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone); polycarbonate polyols obtained by reacting low-molecular-weight polyols with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, and phosgene; polybutadiene glycols; and glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A.

[0043] Plant-derived raw materials can also be used as the general-purpose polyol. Using a plant-derived polyol is preferable because it can increase the biomass content of the ink. Examples of plant-derived general-purpose polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, and isosorbide.

[0044] Polyisocyanate Examples of polyisocyanates used in polyurethane resins include diisocyanates, such as known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates.

[0045] Examples of aromatic diisocyanates include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-2,5-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7-diisocyanate, 1,1-dinaphthyl-2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 3-3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate, and the like.

[0046] Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0047] Examples of alicyclic diisocyanates include 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-di(isocyanatemethyl)cyclohexane, 1,4-di(isocyanatemethyl)cyclohexane, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, and 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate.

[0048] The polyisocyanate is preferably an aliphatic polyisocyanate and / or an alicyclic polyisocyanate, as these provide adequate flexibility. Furthermore, the isocyanate is more preferably isophorone diisocyanate or hexamethylene diisocyanate, as these can further improve adhesive strength.

[0049] Plant-derived raw materials can also be used as the polyisocyanate. Using plant-derived polyisocyanates is preferable because it increases the biomass content of the ink. Examples of plant-derived polyisocyanates include 1,5-pentamethylene diisocyanate and dimer diisocyanate.

[0050] Chain extender The polyurethane resin may contain a chain extender. Examples of the chain extender include diamine compounds such as ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, diethylenetriamine, triethylenetetratriamine, toluylenediamine, and xylenediamine; and amines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine.

[0051] A reaction terminator may be used for the polyurethane resin. Examples of reaction terminators include polyamine compounds, dialkylamines such as di-n-butylamine, and alcohols such as ethanol and isopropyl alcohol. When a polyamine compound is used as a reaction terminator, the pigment concentration of the ink can be increased due to the pigment dispersion effect, which is preferable.

[0052] The polyamine compound is preferably a polyamine compound having an amino group or an imino (—NH—) group at its terminal, such as ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, diethylenetriamine, triethylenetetratriamine, toluylenediamine, xylenediamine, N-(2-hydroxyethyl)ethylenediamine, and N-(2-hydroxyethyl)propyleneamine.

[0053] When it is desired to introduce a carboxyl group into the polyurethane resin, an amino acid such as glycine or L-alanine can be used as a reaction terminator.

[0054] The polyurethane resin may have a linear structure or a branched structure, and in one embodiment, the polyurethane resin has a linear structure.

[0055] The polyurethane resin can be produced, for example, by the following two-stage method or one-stage method, with the two-stage method being preferred.

[0056] The two-stage method includes a first stage in which a polyester polyol and a polyisocyanate are reacted in such a ratio that the isocyanate groups are in excess to obtain a prepolymer having terminal isocyanate groups, and a second stage in which the prepolymer obtained in the first stage is reacted with a chain extender and / or a terminal blocking agent in a solvent.

[0057] In the first stage, in addition to the polyester polyol, a polyether polyol or a general-purpose polyol may be used.

[0058] Examples of the solvent in the two-stage method include ester-based solvents such as ethyl acetate, propyl acetate, and butyl acetate; ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, and n-butanol; hydrocarbon-based solvents such as toluene, xylene, methylcyclohexane, and ethylcyclohexane; and mixed solvents thereof.

[0059] In the one-step method, a polyester polyol, a polyisocyanate, a chain extender and / or an endblocker are reacted in a solvent at once. In the one-step method, a polyether polyol or a general-purpose polyol may be used in addition to the polyester polyol.

[0060] The Mw of the polyurethane resin is preferably within the range of 10,000 to 100,000. If the Mw of the polyurethane resin is 10,000 or more, the blocking resistance of the resulting ink and the strength and oil resistance of the printed film are unlikely to decrease, and sufficient laminate strength can be obtained. If the Mw of the polyurethane resin is 100,000 or less, the viscosity of the resulting ink does not become too high, and the gloss of the printed film is easily maintained.

[0061] The content of polyurethane resin relative to the total mass of the ink (total mass of the ink including solvents, etc.) is preferably 3% by mass or more to ensure sufficient adhesion of the ink to the substrate, and 25% by mass or less to ensure appropriate ink viscosity and work efficiency during ink production and printing, with a range of 5 to 15% by mass being more preferable.

[0062] Resins other than polyurethane resins may be used in the ink. Examples of resins other than polyurethane resins include resins used in inks. Examples of resins other than polyurethane resins include cellulose-based resins, vinyl chloride-vinyl acetate copolymer resins, vinyl chloride-acrylic copolymer resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, polyamide resins, acrylic resins, polyester resins, alkyd resins, polyvinyl chloride resins, rosin-based resins, rosin-modified maleic acid resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, polyvinyl butyral resins, and petroleum resins.

[0063] In one embodiment of the laminate of the present invention, the ink layer further contains one or more resins selected from the group consisting of cellulose-based resins, polyester resins, acrylic resins, polyamide resins, rosin-modified maleic acid resins, and polyvinyl butyral resins.

[0064] The content of resins other than polyurethane resin is preferably 0.5 to 25% by mass, more preferably 1 to 15% by mass, based on the total mass of the ink (total mass of the ink including the solvent, etc.).

[0065] The chlorine content of the solids of all resins in the ink (including all resins other than polyurethane resins, if any, are included) is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass. Because unavoidable amounts of chlorine may be present during the resin production process, the chlorine content may be greater than 0% by mass. By keeping the chlorine content in the resin at 5% by mass or less, the amount of chlorine gas emitted during the production of recycled pellets from the resin can be reduced, which is preferable from the viewpoint of equipment maintenance. Furthermore, liquid ink compositions using such resins are particularly suitable for use as inks for extrusion lamination, where the binder resin is exposed to high temperatures during recycling.

[0066] The chlorine content is calculated by the following formula: Chlorine content in the total resin solids in the ink = (chlorine content in the total resin solids in the ink) / (mass of the total resin solids in the ink)

[0067] (hardening agent) The ink may contain a curing agent. Examples of the curing agent include those used in organic solvent-based inks, and isocyanate-based curing agents are preferred.

[0068] From the viewpoint of curing efficiency, the amount of the isocyanate curing agent is preferably in the range of 0.3% by mass to 10.0% by mass, more preferably 1.0% by mass to 7.0% by mass, based on the total amount of ink solids.

[0069] (organic solvent) The organic solvent used in the ink is not particularly limited, and any known organic solvent can be used, such as ethyl acetate, propyl acetate, isopropanol, or normal propanol.

[0070] The ink may contain water as a volatile component in addition to the organic solvent. Water can control the drying speed of the ink, and in gravure printing in particular, it can beautifully reproduce the gradation areas that are characterized by low ink transfer.

[0071] The amount of water is preferably in the range of 0.3 to 10% by mass of the total ink mass (total mass of ink including solvents) to ensure good printability. If the amount of water is 0.3% by mass or more, the ink drying suppression effect is not reduced, and the reproducibility of gradation areas tends to be good. Furthermore, if the amount of water is 10% by mass or less of the total ink mass, a decrease in ink stability can be suppressed.

[0072] (coloring agent) The ink may contain a colorant. Examples of the colorant include known inorganic pigments, organic pigments, and dyes that are commonly used in inks, paints, recording agents, and the like.

[0073] Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, etc. In addition, both non-acid-treated pigments and acid-treated pigments can be used.

[0074] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, and gypsum.

[0075] The amount of pigment may be adjusted as appropriate, and is preferably 1 to 60% by mass, for example, relative to the total mass of the ink, and is preferably 10 to 90% by mass in terms of the solid content weight ratio in the ink.

[0076] The ink may also contain, as necessary, a chelate crosslinking agent, an extender pigment, a pigment dispersant, a leveling agent, an antifoaming agent, a wax, a plasticizer, an infrared absorbing agent, an ultraviolet absorbing agent, an aromatic agent, a flame retardant, and the like.

[0077] In one embodiment, the ink is a liquid ink.

[0078] The thickness of the ink layer is, for example, 0.3 to 7.0 μm. In one embodiment, the thickness of the ink layer is 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, 1.1 μm or more, or 1.5 μm or more. In another embodiment, the thickness of the ink layer is 7.0 μm or less, 6.0 μm or less, 5.0 μm or less, 4.0 μm or less, 3.0 μm or less, 2.1 μm or less, 2.0 μm or less, 1.5 μm or less, 1.3 μm or less, 1.0 μm or less, or 0.7 μm or less.

[0079] ·Adhesive layer The adhesive layer contains a reaction product (urethane resin) of a polyol having two or more hydroxyl groups and an isocyanate having an isocyanate group. The urethane resin may have a linear structure or a branched structure.

[0080] In the adhesive layer of the present invention, the amount of isocyanate groups in the isocyanate is in excess relative to the amount of hydroxyl groups in the polyol, and the excess amount of isocyanate groups (the total of isocyanate groups in the urethane resin and isocyanate groups in unreacted isocyanate) is 0.1 mmol / g or more and 2.5 mmol / g or less of the solid content of the adhesive layer.

[0081] The adhesive layer is, for example, a cured coating film of a two-component curing adhesive of a polyisocyanate composition and a polyol composition. In this specification, the adhesive layer composition that forms the adhesive layer is referred to as an "adhesive."

[0082] The two-component curing adhesive contains a polyisocyanate composition (I) and a polyol composition (O).

[0083] (Polyisocyanate composition (I)) The polyisocyanate composition (I) is not particularly limited, and any polyisocyanate composition used in the adhesives technical field can be used. The polyisocyanate composition (I) is, for example, a urethane prepolymer or a mixture of a urethane prepolymer and an isocyanate monomer.

[0084] (Urethane prepolymer (A1)) The urethane prepolymer (hereinafter sometimes referred to as urethane prepolymer (A1)) is not particularly limited, and any urethane prepolymer used in the technical field of adhesives can be used. Generally, a urethane prepolymer obtained by reacting an isocyanate composition with a polyol composition under conditions in which the isocyanate groups contained in the isocyanate composition are in excess relative to the active hydrogen groups contained in the polyol composition is used.

[0085] (Isocyanate composition) The isocyanate composition contains an isocyanate. The isocyanate is not particularly limited, and examples thereof include aromatic diisocyanates, araliphatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates; biuret, nurate, adduct, allophanate, carbodiimide-modified, and uretdione-modified products of these diisocyanates; and urethane prepolymers obtained by reacting these polyisocyanates with polyols.

[0086] Examples of aromatic diisocyanates include 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (also called polymeric MDI or crude MDI), 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate.

[0087] The araliphatic diisocyanate refers to an aliphatic isocyanate having one or more aromatic rings in the molecule. Examples of the araliphatic diisocyanate include m-xylylene diisocyanate, p-xylylene diisocyanate, and α,α,α',α'-tetramethylxylylene diisocyanate.

[0088] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0089] Examples of alicyclic diisocyanates include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, isophorone diisocyanate (also known as IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,4-bis(isocyanatomethyl)cyclohexane.

[0090] (Polyol composition) The polyol composition includes a polyol. The polyol is not particularly limited, and examples thereof include glycols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, and pentaerythritol; bisphenols such as bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F; and dimer diol. In addition, as the polyol, for example, the polyol compounds described in JP-A-2023-094545 can also be used.

[0091] The polyol may be a polyester polyol obtained by reacting a polyol with a polycarboxylic acid. In addition, polyester polyols (1) to (5) described in JP-A-2023-094545 may be used.

[0092] Examples of polycarboxylic acids include aromatic polybasic acids such as orthophthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic anhydride, naphthalic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, benzophenonetetracarboxylic acid, benzophenonetetracarboxylic dianhydride, 5-sodium sulfoisophthalic acid, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride; methyl esters of aromatic polybasic acids such as dimethyl terephthalic acid and dimethyl 2,6-naphthalenedicarboxylate; malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid. aliphatic polybasic acids such as sebacic acid, fumaric acid, maleic acid, maleic anhydride, and itaconic acid; alkyl esters of aliphatic polybasic acids such as dimethyl malonate, diethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, diethyl pimelate, diethyl sebacate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, and diethyl maleate; and alicyclic polybasic acids such as 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, cyclohexane-1,2,4-tricarboxylic-1,2-anhydride, himic anhydride, and HET anhydride.

[0093] The polyol preferably includes at least one of polyether polyol and polyester polyol.

[0094] A urea derivative or biuret derivative may be introduced into the urethane prepolymer by using an amine compound in the polyol composition. In this case, the amine compound used preferably includes a primary or secondary monoamine compound.

[0095] Examples of primary monoamine compounds include methylamine, ethylamine, propylamine, isopropylamine, butylamine, amylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine (laurylamine), tridodecylamine, tetradecylamine (myristylamine), pentadecylamine, cetylamine, stearylamine, oleylamine, cocoalkylamine, tallow alkylamine, hardened tallow alkylamine, allylamine, aniline, and benzylamine.

[0096] Examples of secondary monoamine compounds include dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, diamylamine, diallylamine, methylaniline, ethylaniline, dibenzylamine, diphenylamine, dicocoalkylamine, di-hardened beef tallow alkylamine, and distearylamine.

[0097] The amount of the monoamine compound is preferably 40% by mass or less of the total solid content of the polyol composition.

[0098] The urethane prepolymer (A1) is obtained by reacting an isocyanate composition with a polyol composition under conditions in which the isocyanate groups contained in the isocyanate composition are in excess relative to the active hydrogen groups contained in the polyol composition. The equivalent ratio of the isocyanate groups to the active hydrogen groups contained in the polyol composition, [NCO] / [active hydrogen groups], can be appropriately adjusted depending on the purpose, but is, for example, 2.0 to 20.0.

[0099] (Isocyanate Monomer (A2)) The isocyanate monomer (hereinafter sometimes referred to as isocyanate monomer (A2)) may be any isocyanate monomer that can be commonly used in synthesizing a urethane prepolymer of the isocyanate composition in the urethane prepolymer (A1). It may also be a biuret, nurate, adduct, or allophanate of the isocyanate monomer, or a polyurethane polyisocyanate that is a reaction product of these diisocyanates with a high molecular weight polyol (such as a polyester polyol or a polyether polyol). Examples of the isocyanate monomer (A2) include nurate forms of hexamethylene diisocyanate, nurate forms of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate and its biuret form, nurate form, adduct form, allophanate form, polyurethane polyisocyanate, carbodiimide-modified diphenylmethane diisocyanate, allophanate-modified diphenylmethane diisocyanate, and polymeric diphenylmethane diisocyanate.

[0100] When the polyisocyanate composition (I) is used as a solventless two-component curing adhesive, the viscosity of the polyisocyanate composition (I) is in a range suitable for the non-solvent lamination method. For example, the viscosity of the polyisocyanate composition (I) at 25°C is in the range of 1000 to 10000 mPas, more preferably 1000 to 5000 mPas. The viscosity of the polyisocyanate composition (I) can be adjusted, for example, by the amount of urethane prepolymer or isocyanate monomer added.

[0101] (Polyol composition (O)) The polyol composition (O) contains a polyol having multiple hydroxyl groups. The polyol is not particularly limited, and polyol compounds used in urethane-reactive two-component curing adhesives can be used.

[0102] Examples of polyols include polyether polyols, polyester polyols, polyester polyether polyols, polyurethane polyols, polyester polyurethane polyols, polyether polyurethane polyols, vegetable oil polyols, sugar alcohols, polycarbonate polyols, acrylic polyols, hydroxyl group-containing olefin resins, hydroxyl group-containing fluororesins, and (poly)alkanolamines.

[0103] The polyol may be the same as that described for the urethane prepolymer (A1). The polyol used in the urethane prepolymer (A1) and the polyol used in the polyol composition (O) may be the same or different. The polyol used in the polyol composition (O) is preferably at least one selected from the group consisting of polyether polyols, polyester polyols, polyester polyether polyols, polyurethane polyols, polyester polyurethane polyols, and polyether polyurethane polyols.

[0104] When the two-component curing adhesive is used as a solventless type, the viscosity of the polyol composition (O) is adjusted to a range suitable for the non-solvent lamination method. For example, the viscosity of the polyol composition (O) at 40°C is in the range of 100 to 5000 mPas, more preferably 100 to 3000 mPas.

[0105] The two-component curing adhesive may contain components other than those described above. The other components may be contained in the polyisocyanate composition (I) or the polyol composition (O), or may be prepared separately and mixed with the polyisocyanate composition (I) and the polyol composition (O) immediately before application of the adhesive. Examples of other components include the polyamine (C), monool compound (D), catalyst, acid anhydride, pigment, plasticizer, and phosphoric acid compound described in JP 2023-094545 A.

[0106] The two-component curing adhesive may be either a solvent-based or solventless type.

[0107] In this specification, the term "solvent-based" adhesive refers to a form used in a so-called dry lamination method, in which the adhesive is applied to a substrate, heated in an oven or the like to volatilize the organic solvent in the coating, and then laminated to another substrate. The polyisocyanate composition (I) or the polyol composition (O) contains an organic solvent.

[0108] Examples of organic solvents include esters such as ethyl acetate, butyl acetate, and cellosolve acetate; ketones such as acetone, methyl ethyl ketone, isobutyl ketone, and cyclohexanone; ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; dimethyl sulfoxide; and dimethyl sulfamide.

[0109] In this specification, the term "solventless" adhesive refers to a form of adhesive used in a method in which the polyisocyanate composition (I) and the polyol composition (O) are substantially free of organic solvents, and the adhesive is applied to a substrate and then bonded to another substrate without undergoing a step of heating in an oven or the like to volatilize the solvent, i.e., a non-solvent lamination method.

[0110] The two-component curing adhesive preferably has a ratio [NCO] / [OH] of the number of moles [NCO] of isocyanate groups contained in the polyisocyanate composition (I) to the number of moles [OH] of hydroxyl groups contained in the polyol composition (O) of 1.0 to 3.0, which allows for appropriate curing properties to be obtained regardless of the environmental humidity at the time of application.

[0111] (biomass adhesive) In the two-component curing adhesive used in the present invention, in consideration of the establishment of a recycling-oriented society that should continue to develop (sustainability), it is preferable to use plant-derived raw materials as raw materials for the polyisocyanate composition (I) or the polyol composition (O).

[0112] The biomass content can be increased by appropriately using biomass raw materials as raw materials for the two-component curing adhesive used in the present invention. Examples of biomass raw materials include castor oil-based polyols such as castor oil, dehydrated castor oil, hydrogenated castor oil (a hydrogenated castor oil), and 5-50 mol alkylene oxide adducts of castor oil; aliphatic polybasic acids such as succinic acid, succinic anhydride, glutaric acid, adipic acid, azelaic acid, sebacic acid, and itaconic acid; alkyl esters of these acids; and dimer acids.

[0113] Commercially available biomass adhesives can also be used, such as adhesives listed by the Japan Organics Recycling Association.

[0114] The weight of the adhesive layer after drying is 0.1 to 10 g / m 2 It is preferable that the amount is 1 to 6 g / m 2 More preferably, it is 2 to 5 g / m 2 It is more preferable that:

[0115] The thickness of the adhesive layer is preferably 0.1 to 10 μm, more preferably 1 to 7 μm, and even more preferably 2 to 5 μm.

[0116] Second Film The second plastic film can be made of the same material as the first plastic film, and the first plastic film and the second plastic film can be made of the same or different materials.

[0117] The second plastic film preferably includes a melt-extruded resin layer. Here, "melt-extruded resin layer" refers to a resin layer formed by laminating a molten resin onto the surface of an ink layer or the like in an extrusion laminate configuration. The melt-extruded resin layer is preferably an olefin-based resin such as polyethylene or polypropylene. Furthermore, as such materials, both the first plastic film and the second plastic film are preferably polyolefin resins. From the viewpoint of improving recyclability, the olefin ratio in the laminate is preferably 80% or more, more preferably 90% or more, and even more preferably 90% or more.

[0118] Other layers The laminate of the present invention may have any layer depending on the purpose in addition to the first plastic film, the ink layer, the adhesive layer, and the second plastic film. Examples of the other layer include a detachable primer layer, a sealant film, a metal-vapor-deposited unstretched film, a metal-vapor-deposited stretched film, and a transparent metal-vapor-deposited stretched film.

[0119] Detachable primer layer The laminate may have one or more removable primer layers. The removable primer layer (hereinafter sometimes referred to as "primer layer") is a layer that, when provided adjacent to the first plastic film, the second plastic film, the ink layer, or the adhesive layer, facilitates peeling off the ink layer or separating the laminate film into single-layer films. By providing a primer layer in the laminate, the recyclability of the laminate can be improved, and by providing a primer layer adjacent to a desired layer, the desired layer can be easily separated, improving the quality of the recycled plastic.

[0120] Fig. 2 is a schematic diagram showing a cross section of another example of the laminate of the present invention. In the example of Fig. 2, the laminate 1 has, adjacent to each other in this order, a first plastic film 10, a detachable primer layer 50, an ink layer 20, an adhesive layer 30, and a second plastic film 40.

[0121] Fig. 3 is a schematic diagram showing a cross section of another example of the laminate of the present invention. In the example of Fig. 3, the laminate 1 has, adjacent to each other in order, a first plastic film 10, a detachable primer layer 50, an ink layer 20, an adhesive layer 30, a detachable primer layer 50, and a second plastic film 40.

[0122] In recent years, there has been a demand not only for further improvements in laminate strength but also for increased recycling rates for resources such as flexible packaging and plastic bottles. However, conventional recycling methods have a problem in that the ink layer printed on the plastic substrate does not come off the plastic substrate during the recycling process. Furthermore, there is a problem in that the ink layer becomes mixed into the plastic, causing a deterioration in the color and physical properties of the recycled plastic, thereby reducing the value of the recycled plastic.

[0123] In response to this issue, for example, by using a removable primer layer adjacent to the ink layer, the ink layer can be easily removed from the plastic substrate during the recycling process, preventing deterioration in the color and physical properties of the recycled plastic. This increases the value of recycled plastic, leading to the entry of new recyclers and the establishment of separate collection systems by local governments. Furthermore, improving the recycling rate will also help alleviate the problem of marine plastics.

[0124] Furthermore, conventionally, there has been a problem in that the colored pigment contained in the ink layer is released into the washing liquid during washing, causing the washing liquid to become colored, and when the wastewater becomes colored, wastewater treatment is required.

[0125] To address this issue, for example, by using a detachable primer layer adjacent to the ink layer, it is possible to detach the ink layer from the plastic substrate during the recycling process, suppressing the release of pigment into the cleaning solution and reducing the environmental burden.

[0126] In one embodiment of the laminate of the present invention, a detachable primer layer is further provided on one or both of the surfaces between the first plastic film and the ink layer and the surface between the adhesive layer and the second plastic film.

[0127] The primer layer is preferably a coating that can be detached from the substrate by treatment with a detachment treatment liquid such as an alkaline solution. Any known layer can be used as the layer that can be detached from the substrate by treatment with a detachment treatment liquid. For example, when an alkaline solution is used, the layer dissolves or swells in the alkaline solution and is detached from the substrate.

[0128] There are no particular restrictions on the primer layer-forming composition that forms the primer layer, as long as it is a coating that can be detached from the substrate by treatment with an alkaline solution. However, since the primer layer is easily dissolved or hydrolyzed by an alkaline solution, it is preferable that the primer layer-forming composition contain a compound having an acidic group, a water-soluble resin, and an inorganic material that becomes soluble by treatment with an alkaline solution.

[0129] As the compound having an acidic group, a resin having an acidic group or a low molecular weight compound having an acidic group can be used.

[0130] Examples of resins having an acidic group include resins having an acid value such as urethane resins, cellulose-based resins, ketone resins, polyester resins, rosin-modified maleic acid resins, rosin-modified fumaric acid resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, cyclized rubber, chlorinated rubber, butyral resins, and petroleum resins, as well as radical copolymer resins such as styrene-(meth)acrylic resins, styrene-maleic (anhydride) resins, and terpene-maleic (anhydride) resins obtained by copolymerizing polymerizable monomers having an acidic group, such as polymerizable monomers having a carboxyl group such as itaconic acid, maleic acid, fumaric acid, cinnamic acid, or acid anhydrides thereof, polymerizable monomers having a sulfonic acid group such as sulfonated styrene, and polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide, and acid-modified polyolefin resins.

[0131] As the resin having an acidic group, a urethane resin having an acidic group, an acrylic resin having an acidic group, a resin having an acid value such as a rosin-modified maleic acid resin or a rosin-modified fumaric acid resin, or a styrene-maleic (anhydride) resin is more preferred.

[0132] The acid value of the resin having an acidic group is, for example, 150 mgKOH / g or more, and preferably 150 to 500 mgKOH / g.

[0133] The molecular weight of the resin having an acidic group is preferably, for example, in the range of 500 to 20,000 in terms of Mw.

[0134] The low molecular weight compound having an acidic group may be, for example, an organic acid. Preferred examples of the low molecular weight compound having an acidic group include saturated fatty acids, unsaturated fatty acids, hydroxy acids, aromatic carboxylic acids, dicarboxylic acids, tricarboxylic acids, oxocarboxylic acids, and carboxylic acid derivatives.

[0135] Examples of saturated fatty acids include lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, decanoic acid, undecanoic acid, and dodecanoic acid.

[0136] Examples of unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and sorbic acid.

[0137] Examples of hydroxy acids include lactic acid, malic acid, and citric acid.

[0138] Examples of aromatic carboxylic acids include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid.

[0139] Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimer acid, fumaric acid, maleic acid, and azelaic acid.

[0140] Examples of tricarboxylic acids include aconitic acid and trimer acid.

[0141] Examples of oxocarboxylic acids include pyruvic acid and oxaloacetic acid.

[0142] Examples of the carboxylic acid derivative include amino acids and nitrocarboxylic acids, and these can be used singly or in combination.

[0143] The number of carbon atoms in the organic acid is preferably 3 or more, preferably 4 or more, preferably 5 or more, preferably 6 or more, preferably 7 or more, and preferably 8 or more. By making the number of carbon atoms in the organic acid 3 or more, it is possible to improve adhesion to the substrate. Furthermore, the number of carbon atoms in the organic acid is preferably 20 or less, preferably 18 or less, and preferably 16 or less. By making the number of carbon atoms in the organic acid 20 or less, it is possible to improve dispersibility in an aqueous medium.

[0144] The acid value of the compound having an acidic group is, for example, preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, more preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, more preferably 30 mgKOH / g or more, more preferably 40 mgKOH / g or more, more preferably 50 mgKOH / g or more. The acid value of the compound having an acidic group is preferably 900 mgKOH / g or less, more preferably 850 mgKOH / g or less, more preferably 800 mgKOH / g or less, more preferably 750 mgKOH / g or less, more preferably 700 mgKOH / g or less, more preferably 650 mgKOH / g or less, more preferably 600 mgKOH / g or less, more preferably 550 mgKOH / g or less. By setting it to 50 mgKOH / g or more and 550 mgKOH / g or less, it is possible to achieve both alkaline solution releasability and adhesion to the substrate.

[0145] The water-soluble resin may be any resin that swells or dissolves in water and can be released from the plastic substrate. Such resins can be selected from known resins as long as they do not impair water solubility, and examples thereof include water-soluble polyester resins, water-soluble polyamide resins, water-soluble polyimide resins, water-soluble acrylic resins, water-soluble polyurethane resins, water-soluble polyallylamine resins, water-soluble phenolic resins, water-soluble epoxy resins, water-soluble phenoxy resins, water-soluble urea resins, water-soluble melamine resins, polyvinyl alcohol resins, and modified products of these resins. Among these, polyvinyl alcohol (PVA) resins are preferably used from the viewpoints of availability and release properties.

[0146] The primer layer containing polyvinyl alcohol is preferably a resin layer containing at least 25% by mass of polyvinyl alcohol.

[0147] Examples of inorganic materials that become soluble when treated with an alkaline solution (hereinafter sometimes referred to as "soluble inorganic materials") include inorganic oxides such as alumina, silica, zirconia, magnesia, ceria, yttria, zinc oxide, and iron oxide; inorganic nitrides such as silicon nitride, titanium nitride, and boron nitride; ceramics such as silicon carbide, calcium carbonate, magnesium sulfate, aluminum sulfate, aluminum hydroxide, aluminum oxide hydroxide, potassium titanate, talc, kaolinite, dickite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amesite, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate, diatomaceous earth, and silica sand; metals such as aluminum; and glass fiber. These inorganic materials are soluble in alkaline solutions, which contributes to the release function of the primer layer.

[0148] The form containing the soluble inorganic material may be a layer containing particles containing the soluble inorganic material and a binder resin, or may be a vapor-deposited layer of the soluble inorganic material.

[0149] When a layer containing a binder resin is used, examples of the binder resin include cellulose-based resins, urethane resins, polyamide resins, vinyl chloride-vinyl acetate copolymer resins, ketone resins, polyester resins, (meth)acrylic resins, rosin-modified maleic acid resins, rosin-modified fumaric acid resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, cyclized rubbers, chlorinated rubbers, butyral resins, and petroleum resins. Among these, urethane resins, (meth)acrylic resins, rosin-based resins, and modified products thereof are often used in appropriate combination.

[0150] The mass ratio of the binder resin to the metal particles (binder resin:metal particles) is preferably 90:10 to 20:80.

[0151] In the case of a vapor-deposited layer, the vapor-deposited layer is preferably made of at least one material selected from alumina, silica, and aluminum.

[0152] The vapor deposition layer can be formed by a conventionally known method, and its composition and forming method are not particularly limited.

[0153] The primer layer is obtained by applying a primer layer-forming composition containing the above-mentioned resin, a solvent such as an organic solvent or an aqueous solvent, an auxiliary, etc. to a substrate and drying the composition. The amount of the primer layer-forming composition applied is, for example, about 0.1 to 5 μm (dry thickness).

[0154] The primer layer-forming composition can be applied by, for example, gravure printing, letterpress printing, flexography, roll coating, reverse coating, spraying, or the like.

[0155] The formation of the primer layer and the formation of the ink layer thereon may be carried out continuously (in-line), or the formation of the primer layer and the formation of the ink layer may be carried out separately.

[0156] Examples of sealant films include CPP film (unstretched polypropylene film) and LLDPE film (linear low-density polyethylene resin film).

[0157] As the metal-deposited unstretched film, for example, a VM-CPP film obtained by depositing a metal such as aluminum on a CPP film can be used.

[0158] As the metal-deposited stretched film, for example, a VM-OPP film obtained by depositing a metal such as aluminum on an OPP film can be used.

[0159] Examples of transparent vapor-deposited stretched films include films obtained by depositing silica or alumina on OPP film, PET film, nylon film, etc. For the purpose of protecting the inorganic vapor-deposited layer of silica or alumina, a film having a coating applied to the vapor-deposited layer may also be used.

[0160] The metal layer may be, for example, an aluminum foil.

[0161] The laminate of the present invention can be applied to various molded articles such as electronic equipment, building materials, textiles and leather, home appliances, vehicles such as cars and airplanes, furniture, office supplies, play equipment, sporting goods, and molded parts thereof. The laminate of the present invention can also be applied to packaging materials (more specifically, multilayer packaging materials). Additionally, the laminate of the present invention can be used as a multilayer packaging material. When used as a multilayer packaging material, the layer structure can be changed depending on the contents, the environment of use, and the form of use.

[0162] When the laminate of the present invention is used as a packaging material, for example, the contents are filled through the opening, and then the opening is heat-sealed to produce a product using the packaging material formed from the laminate of the present invention. The use of the packaging material is not particularly limited, but it can be used as a packaging material for, for example, food, medicine, sanitary products, cosmetics, electronic equipment, building materials, industrial materials, etc., and is particularly suitable for use in electronic equipment.

[0163] The laminate of the present invention or a packaging material made of the laminate can be processed as it is by a known recycling plastic processing method and used as a recycled material.

[0164] A recycled material can be obtained by a manufacturing method including the steps of crushing the laminate or packaging material of the present invention, melt-kneading the crushed film pieces, and pelletizing the melt-kneaded mixture.

[0165] Furthermore, a recycled plastic film can be obtained by removing the removable primer layer adjacent to the plastic film from the laminate of the present invention. An example of a method for removing the removable primer layer from the laminate using an alkaline solution will be described below.

[0166] The detachable primer layer can be detached (removed) from the plastic film by, for example, immersing it in an alkaline aqueous solution at 60° C. or higher.

[0167] The alkaline substance contained in the alkaline aqueous solution is not particularly limited, and examples thereof include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), ammonia, etc. NaOH or KOH is preferred as the alkaline substance.

[0168] An alkaline aqueous solution can be prepared by uniformly dissolving or dispersing NaOH, KOH, ammonia, etc. in water and adjusting the concentration or pH to a desired level.

[0169] The time for immersing the laminate in the alkaline aqueous solution may be adjusted as appropriate, and is, for example, within 24 hours, preferably within 12 hours, and more preferably within 6 hours.

[0170] The recycled plastic film can then be crushed, for example, using a crusher, and the crushed plastic film pieces can be melted and kneaded, and molded using a molding machine to obtain recycled plastic pellets.

[0171] As the crusher, a known crusher may be used.

[0172] The crushed plastic film pieces are then physically blended using methods such as melt kneading, solvent cast blending, latex blending, polymer complexing, etc. The melt kneading method is particularly popular.

[0173] Examples of the kneading device include a tumbler, a Henschel mixer, a rotary mixer, a super mixer, a ribbon tumbler, a V blender, etc. After melt-kneading using such a kneading device, the material is pelletized.

[0174] A single-screw or multi-screw extruder is generally used for melt-kneading and pelletizing, and the plastic film pieces may be charged as they are, or may be charged after being subjected to a compression volume reduction treatment with or without heating.

[0175] In addition to these extruders, a Banbury mixer, a roller, a co-kneader, a blast mill, a Prabender blastograph, etc. may also be used.

[0176] Alternatively, the resin may be used as a molding resin and melt-kneaded in the heating barrel of a molding machine without being melt-kneaded.

[0177] The recycled plastic pellets may be either deinked and delaminated plastic or non-deinked and non-delaminated laminates, but the former have higher purity and are therefore more valuable as recycled materials. Therefore, it is possible to process films using the recycled plastic pellets obtained by the present invention. [Example]

[0178] The present invention will be described in more detail below by way of examples, but these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

[0179] The plastic films used in the examples are as follows: Biaxially oriented polypropylene film (OPP film): Futamura Chemical Co., Ltd., "FOR 20 μm" Non-oriented polypropylene film (CPP film): Toyobo Co., Ltd., "Pylen (registered trademark) Film-CT P1128", 30 μm Low-density polyethylene film (LLDPE): RM Tocello Co., Ltd., "TUX HC", 60 μm Polyethylene film (PE): Futamura Chemical Co., Ltd., "PE3K-H", 25 μm

[0180] The raw materials used to synthesize the polyurethane resin for the ink layer are as follows: Polyester polyol (#1000): "Teslac 2464" manufactured by Resonac Polyester polyol (#2000): "Teslac TA22-981" manufactured by Resonac Polyester polyol (#3000): Kuraray Polyol P-3010 Polyester polyol (#5000): Kuraray Polyol P-5010 Polyether polyol (#400): NOF Corporation, "PEG#400" Polyether polyol (#1000): NOF Corporation, "PEG#1000" Isophorone diisocyanate (IPDI) Isophoronediamine (IPDA) Cyclohexylamine (CHA)

[0181] Other ingredients of the ink layer are as follows: Polyvinyl butyral resin 15% solution: Polyvinyl butyral resin (Mw 10,000, hydroxyl group content 15% by mass, glass transition temperature 60°C, acetyl group content 8% by mass) obtained by reacting polyvinyl alcohol with butyraldehyde, non-volatile content 15%, dissolved in isopropyl alcohol, referred to as "PVB solution" in the table. 15% vinyl chloride-vinyl acetate copolymer resin solution: Solvin A manufactured by Nissin Chemical Industry Co., Ltd., 15% non-volatile content, normal propyl acetate solution, referred to as "Solvin" in the table Cellulose resin solution: Eastman Chemical Co., "CAP-482-0.5", non-volatile content 20%, ethyl acetate / IPA solution, indicated as "CAP" in the table Maleic acid resin 50% solution: Arakawa Chemical Co., Ltd., "Marquid #32", non-volatile content 50%, dissolved in isopropyl alcohol, referred to as "Marquid" in the table. Fine particle silica: Fuji Silysia Chemical Co., Ltd., "Sylysia (registered trademark) 350", referred to as "silica" in the table Pigment: Phthalocyanine blue pigment, DIC "FASTOGEN BLUE LA5380", indicated as "LA5380" in the table JR-809: Titanium dioxide for pigments, manufactured by Teika Corporation, "JR-809", indicated as "JR-809" in the table

[0182] The raw materials used to prepare the adhesive are listed in Table 2. [Table 1]

[0183] The raw materials used in the preparation of the composition for forming a primer layer are as follows. Crosslinking agent: Nisshinbo Chemical "Carbodilite SV-02" Vinyl alcohol resin: Mitsubishi Chemical Corporation, "Nichigo G-polymer (registered trademark) AZF8035Q", Mw 24,000, solids 100% Polyethyleneimine: Nippon Shokubai Co., Ltd., "Epomin (registered trademark) P-1000", solid content 30%)

[0184] (amine value) The amine value is the amount of potassium hydroxide (mg) equivalent to the amount of hydrochloric acid required to neutralize the amino groups in 1 g of sample, and was measured according to JIS K 0070. Specifically, 0.5 to 2 g of sample was precisely weighed (sample solids: 5 g). 50 mL of a 60 / 40 (mass ratio) mixed solution of methanol and methyl ethyl ketone was added to dissolve the precisely weighed sample. Bromophenol blue was added as an indicator to the resulting solution, and the resulting solution was titrated with 0.2 mol / L ethanolic hydrochloric acid solution (titer: f). The point at which the solution color changed from green to yellow was defined as the endpoint, and the titer (A mL) at this point was used to calculate the amine value according to the following formula: Amine value = (A × f × 0.2 × 56.108) / S [mgKOH / g]

[0185] (Synthesis of polyurethane resin for ink layer) 50 parts by weight of IPDI and 150 parts by weight of polyester polyol #1000 were added to a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube. The mixture was reacted at 85°C for 6 hours under a nitrogen stream. Next, 50 parts by weight of ethyl acetate was added to the mixture to form a homogeneous solution, yielding prepolymer A. Next, prepolymer A was added to a mixed solution containing 298 parts by weight of ethyl acetate, 149 parts by weight of isopropanol, 11.7 parts by weight of IPDA, and 1.4 parts by weight of CHA. The mixture was reacted at 40°C for 4 hours under a nitrogen stream to yield polyurethane resin PU1-1. Polyurethane resin PU1-1 had a nonvolatile content of 30%, an amine value of 0.29 mgKOH / g on the solids, and an Mn of 28,000.

[0186] Polyurethane resins PU1-2 to PU1-7, PU2-1 to PU2-5, PU3-1 to PU3-4, and PU4-1 to PU4-3 were synthesized in the same manner except that the raw material compositions were changed as shown in Table 2. The physical properties of the polyurethane resins are also shown in Table 2.

[0187] [Table 2]

[0188] (Ink preparation) Inks were prepared according to the formulations shown in Tables 3 to 6.

[0189] [Table 3]

[0190] [Table 4]

[0191] [Table 5]

[0192] [Table 6]

[0193] (Preparation of adhesive) Solvent-based adhesives were prepared according to the formulations shown in Tables 7 and 8.

[0194] [Table 7] The base resins and curing agents in Table 7 are as follows: Main ingredient 1: Polyether polyurethane polyol Main ingredient 2: Polyester polyurethane polyol Hardener 1: Aromatic isocyanate Hardener 2: Aromatic isocyanate Hardener 3: Aliphatic isocyanate

[0195] [Table 8] The base resins and curing agents in Table 8 are as follows: Main ingredient 3: Polyester polyol Main ingredient 4: Polyester polyol Hardener 3: Aliphatic isocyanate Hardener 4: Aliphatic isocyanate

[0196] A solvent-free adhesive was prepared according to the formulation shown in Table 9.

[0197] [Table 9] Agents B and A in Table 9 are as follows: Agent B 1: Polyether polyol Agent B 2: Polyester polyol Agent B 3: Polyester polyol Agent A 1: Polyether polyisocyanate Agent A 2: Polyester polyether polyisocyanate Agent A 3: Polyisocyanate

[0198] (Synthesis of polyurethane resin for removable primer layer) An aromatic polyester polyol was synthesized by mixing and reacting 0.32 parts by mass of terephthalic acid, 0.32 parts by mass of isophthalic acid, 0.13 parts by mass of ethylene glycol, and 0.23 parts by mass of diethylene glycol. Next, 0.74 parts by mass of the aromatic polyester polyol, 0.20 parts by mass of isophorone diisocyanate, and 0.06 parts by mass of 2,2'-dimethylolpropionic acid were added to a four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, and the mixture was reacted at 75°C for 8 hours under a nitrogen stream to obtain a polyurethane resin.

[0199] (Preparation of Composition PR1 for Forming Removable Primer Layer) 100 parts by mass of the obtained polyurethane resin was mixed with 9 parts by mass of a crosslinking agent to prepare a polyurethane dispersion (PUD)-based composition for a removable primer layer PR1.

[0200] (Preparation of polyvinyl alcohol (PVA)-based detachable primer layer composition) A PVA-based composition for a detachable primer layer was prepared by mixing 10 parts by mass of vinyl alcohol resin, 1.7 parts by mass of polyethyleneimine, 43.3 parts by mass of water, and 45 parts by mass of ethanol.

[0201] (Manufacturing of laminates) Example 1 The viscosity of the prepared ink LI1-1 was adjusted to 16 seconds (25°C) using ethyl acetate in a Zahn cup #3 (Rigo Co., Ltd.). Next, the ink LI1-1 was printed onto an OPP film (first plastic film) using a gravure proofing machine equipped with a 35 μm deep gravure plate, and dried at 40-50°C to obtain an OPP print with an ink layer. A CPP film (second plastic film) was laminated onto the resulting ink layer using adhesive SB1-1 using a dry laminator (DIC Engineering Co., Ltd.). The adhesive coating amount was 2.5-3.5 g / m. 2 Next, the intermediate laminate was aged at 40°C for 3 days to obtain a laminate.

[0202] Examples 2 to 179, Comparative Examples 1 to 60 Laminates were produced in the same manner as in Example 1, except that the types of ink, adhesive, first plastic film, and second plastic film were changed as shown in Tables 10-32.

[0203] Dry laminate strength measurement The laminates of the examples and comparative examples were cut into 15 mm widths to prepare test specimens. A T-peel test was performed on the test specimens at a pulling speed of 300 mm / min. The laminate strength was evaluated according to the following criteria. A rating is the best, and A or B is desirable. The evaluation results are shown in Tables 10 to 32. A: Peel strength is 1.1 to 1.3 N / 15 mm B: Peel strength is 0.8 to 1.0 N / 15 mm C: Peel strength is 0.5 to 0.7 N / 15 mm

[0204] [Table 10]

[0205] [Table 11]

[0206] [Table 12]

[0207] [Table 13]

[0208] [Table 14]

[0209] [Table 15]

[0210] Table 16

[0211] Table 17

[0212] Table 18

[0213] Table 19

[0214] Table 20

[0215] Table 21

[0216] Table 22

[0217] Table 23

[0218] Table 24

[0219] Table 25

[0220] [Table 26]

[0221] [Table 27]

[0222] [Table 28]

[0223] [Table 29]

[0224] [Table 30]

[0225] [Table 31]

[0226] [Table 32]

[0227] (Production of laminate having primer layer) Example 180 An OPP film was used as the first plastic film. Next, primer layer composition PR1 was diluted with isopropyl alcohol to a solids content of 10%. The diluted primer layer composition PR1 was then printed onto the OPP film using a gravure printing machine (manufactured by DIC Engineering) equipped with a gravure plate having a plate depth of 22 μm, forming a first detachable primer layer. Next, an ink layer and an adhesive layer were formed on the first detachable primer layer using ink LI2-4 and adhesive SB1-2 in the same manner as in Example 1, thereby obtaining a laminate.

[0228] Examples 181 to 205, Comparative Examples 61 to 66 A laminate was produced in the same manner as in Example 180, except that the order and types of the first plastic film, first detachable primer layer, ink layer, adhesive layer, second detachable primer layer, and second plastic film were changed as shown in Tables 32 and 33.

[0229] Delamination evaluation The laminate was cut into 20mm x 20mm pieces to prepare test pieces. The test pieces were immersed in a cleaning solution (2% aqueous sodium hydroxide solution) at 80°C and stirred at 400 rpm using a magnetic stirrer for 1 hour, after which the test pieces were removed. After washing with ion-exchanged water and drying, the degree of delamination was evaluated. Grades A and B are desirable. A: Delamination has occurred, and the ink layer and adhesive layer do not remain on either the first or second plastic film. B: Delamination is performed, and the ink layer and adhesive layer remain on one of the first and second plastic films. C: No delamination

[0230] Detergent color evaluation After carrying out the same test as in the delamination evaluation, the cleaning liquid was filtered through a nylon strainer with 90 mesh / inch and an opening diameter of 185 μm, and the presence or absence of coloration of the cleaning liquid after filtration was confirmed visually. A rating of A is desirable. A: The cleaning solution does not become discolored. B: The cleaning solution becomes discolored C: Not rated because delamination is not performed

[0231] [Table 33]

[0232] [Table 34] [Industrial Applicability]

[0233] According to the present invention, it is possible to provide a laminate having improved adhesive strength between the ink layer and the adhesive layer. [Explanation of symbols]

[0234] 1: Laminate 10: First plastic film 20: Ink layer 30: Adhesive layer 40: Second plastic film 50: Removable primer layer

Claims

1. In order, a first plastic film; an ink layer; an adhesive layer; a second plastic film; the ink layer and the adhesive layer are in contact with each other, the adhesive layer contains a reaction product of a polyol having two or more hydroxyl groups and an isocyanate having an isocyanate group, the amount of the isocyanate groups is in excess relative to the amount of the hydroxyl groups, the excess amount of the isocyanate group is 0.1 mmol / g or more and 2.5 mmol / g or less of the solid content of the adhesive layer, The ink layer is made of amino (-NH ２ ) groups.

2. The laminate according to claim 1 , wherein the first plastic film and the second plastic film are made of a polyolefin resin.

3. 3. The laminate according to claim 1, wherein the ink layer further comprises one or more resins selected from the group consisting of cellulose-based resins, polyester resins, acrylic resins, polyamide resins, rosin-modified maleic acid resins, and polyvinyl butyral resins.

4. The laminate according to claim 1 or 2, wherein the polyurethane resin has an amine value of 0.1 mgKOH / g or more and 10 mgKOH / g or less in solid content.

5. 3. The laminate according to claim 1, further comprising a removable primer layer between the first plastic film and the ink layer and / or between the adhesive layer and the second plastic film.

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