Packaging material, and method for manufacturing the same

Abstract

PROBLEM TO BE SOLVED BY THE INVENTION: To provide a packaging material which is excellent in laminate strength and laminate appearance, and is suitable for material recycling.SOLUTION: A packaging material has a base material, a printing layer, an adhesive layer and a sealant in this order, where the packaging material contains 80 mass% or more of a polyolefin resin, an arithmetical average height Sa value stipulated by ISO 25178 on the surface of the printing layer is 2.0 μm or less, and the adhesive layer is a cured product of a solventless type adhesive containing polyol (A) and polyisocyanate (B).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a packaging material and a method for producing the same. [Background technology]

[0002] From the viewpoints of environmental protection and effective use of resources, various studies are being conducted on the recycling of plastic products. In recent years, there has been a particularly high demand for material recycling in order to realize a recycling-oriented society.

[0003] Among plastic products, packaging materials made of plastic films have a multi-layer structure to meet the different required performance for each application. On the other hand, packaging materials containing multiple types of materials are difficult to separate or sort into single materials, making material recycling difficult, so in recent years, mono-material packaging materials, such as those described in Patent Document 1, have been considered.

[0004] Lamination adhesives used in packaging materials are mainly classified into solvent-based and solventless lamination methods, but due to the strengthening of legal regulations and consideration of environmental conservation and safety, there is an increasing demand for switching to solventless types. Recently, the use of solventless adhesives has been considered not only for two-layer structures, which are the main structure of solventless laminates, but also for three-layer or more laminate structures, which were previously performed with solvent-based adhesives. However, solventless adhesives are designed to contain resins with low molecular weights from the viewpoints of handling, cleaning, appearance performance, and pot life, and tend to have a slow rise in cohesive force after lamination compared to solvent-based laminates.

[0005] This makes it easy for defects in appearance to occur due to air bubbles trapped when the solvent-free adhesive is applied, and carbon dioxide gas generated when the polyisocyanate compound, a component of the adhesive, reacts with moisture in the air. Other defects include delamination caused by air bubbles and carbon dioxide gas, and telescoping (the roll becomes bamboo shoot-like when wound up) caused by the laminated film slipping in the shear direction and shifting. If a printed layer is present, these defects are even more likely to occur due to the penetration of the adhesive into the printed layer and the unevenness of the printed layer surface.

[0006] For example, Patent Document 2 describes how the adhesive strength and processed appearance are improved by using a solvent-free adhesive with high tensile shear strength, but does not describe a method for improving the laminate appearance in a substrate having a printed layer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2021-160258 A [Patent Document 2] International Publication No. 2020 / 130073 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a packaging material which is excellent in laminate strength and laminate appearance and is suitable for material recycling. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have found that the above problems can be solved by using the packaging material of the present invention, and have thus completed the present invention.

[0010] That is, the present invention provides a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant in this order, The packaging material contains 80% by mass or more of a polyolefin resin, The arithmetic mean height Sa of the surface of the printing layer as defined in ISO 25178 is 2.0 μm or less; The present invention relates to a packaging material, wherein the adhesive layer is a cured product of a solventless adhesive containing a polyol (A) and a polyisocyanate (B).

[0011] The present invention also relates to the above packaging material, wherein the solvent-free adhesive has a shear stress of 1.5 N or more under the following test conditions. (Test conditions) The solvent-free adhesive was applied in an amount of 1.9 to 2.1 g / m onto the corona-treated surface of a polyethylene terephthalate substrate 1 having a thickness of 25 μm and a wetting tension of the corona-treated surface of 45 to 60 mN / m. 2 An adhesive layer is formed, and the corona-treated surface of substrate 2 having the same thickness and wet tension as substrate 1 is bonded to the substrate 2 so that the bonding area is 25 mm x 25 mm to obtain a test specimen. The test specimen is kept at 20°C and a humidity of 65% for 1 hour, and then a tensile test of substrate 1 and substrate 2 of the test specimen is performed in an environment of 80°C to measure the shear stress.

[0012] The present invention also relates to the above packaging material, wherein the solventless adhesive has a viscosity of 500 to 4000 mPa s at 40°C measured in accordance with JIS K5600-2-3 immediately after mixing the polyol (A) and the polyisocyanate (B) at 40°C.

[0013] The present invention also relates to the above packaging material, wherein the viscosity at 40°C, measured in accordance with JIS K5600-2-3 after blending the solventless adhesive at 40°C and then leaving it to stand at 40°C for 20 minutes, is 6000 mPa s or less.

[0014] The present invention also relates to the above packaging material, wherein the polyol (A) contains structural units derived from a polyether polyol and / or structural units derived from a polyester polyol.

[0015] The present invention also relates to the above packaging material, wherein the printed layer contains a pigment and a binder resin, and the chlorine content of the binder resin is 5 mass % or less.

[0016] The present invention also relates to the above packaging material, wherein the content of the pigment is 30% by mass or less based on the total mass of the printed layer.

[0017] The present invention also relates to the above packaging material, wherein the chlorine content is 0.4 mass % or less based on the total mass of the packaging material.

[0018] The present invention also provides a method for producing a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant in this order, and containing 80% by mass or more of a polyolefin resin, comprising: A step of forming a printing layer on a substrate, the printing layer having a surface having an arithmetic mean height Sa value of 2.0 μm or less as specified in ISO 25178; The present invention relates to a method for producing a packaging material, which includes a step of applying a solventless adhesive containing a polyol (A) and a polyisocyanate (B). Effect of the Invention

[0019] The present invention makes it possible to provide a packaging material which is excellent in laminate strength and laminate appearance and is suitable for material recycling. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The following describes in detail an embodiment of the present invention. However, the description of the components described below is an example of an embodiment of the present invention, and the present invention is not limited to these contents as long as it does not deviate from the gist of the present invention.

[0021] The packaging material of the present invention will be described in detail below. The present invention relates to a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant in this order, the packaging material containing 80% by mass or more of a polyolefin resin, The arithmetic mean height Sa of the surface of the printing layer as defined in ISO 25178 is 2.0 μm or less; The present invention relates to a packaging material, wherein the adhesive layer is a cured product of a solventless adhesive containing a polyol (A) and a polyisocyanate (B). When the packaging material contains 80 mass % or more of polyolefin resin based on the total mass, it is possible to obtain a molding material that is highly recyclable, has good moldability, and can be used for a variety of applications. In addition, it is preferable that the printed layer surface and the adhesive layer are adjacent to each other. By forming an adhesive layer, which is a cured product of a solventless adhesive containing polyol (A) and polyisocyanate (B), on the printed layer surface having an arithmetic mean height Sa value of 2.0 μm or less as specified in ISO25178, the generation of air bubbles is suppressed, and the leveling property and the adhesion between each layer are improved, and a packaging material having excellent laminate strength and laminate appearance can be obtained.

[0022] <Packaging material> The packaging material of the present invention is a packaging material having a structure in which at least a base material, a printing layer, an adhesive layer, and a sealant are laminated in this order. Specific examples of the structure include, but are not limited to, the following structures. In the structure descriptions (1) to (3) below, " / " indicates the boundary between layers. Specific examples of the laminate structure include, starting from the outer layer side (left side), the following laminate structures: (1) Substrate / printed layer / adhesive layer / sealant (2) Substrate / printed layer / adhesive layer / intermediate substrate / adhesive layer / sealant (3) Substrate / printed layer / adhesive layer / first intermediate substrate / adhesive layer / second intermediate substrate / adhesive layer / sealant

[0023] The packaging material contains a polyolefin resin in an amount of 80% by mass or more based on the total mass of the packaging material. The content is more preferably 85% by mass or more, and even more preferably 90% by mass or more. By containing the polyolefin resin in the above range, a molding material can be obtained that has a high degree of ease in the separation process, a high degree of recyclability, good moldability, and can be used for various applications. From the viewpoint of recyclability, the substrate, the sealant, and the intermediate substrate used as needed are preferably made of the same material (monomaterial).The substrate, the sealant, and the intermediate substrate used as needed are preferably made of a polyolefin resin. Furthermore, of the total mass of the substrate and sealant, and any intermediate substrate used as needed, the polyolefin resin preferably accounts for 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and particularly preferably 95 mass% or more. Moreover, the polyolefin resin is more preferably a polypropylene-based resin and / or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and / or butene.

[0024] <Chlorine content in packaging materials> Due to halogen elements that may be contained in the packaging material, halogen gas or hydrogen chloride, an acidic gas, may be generated during pellet production, which may damage equipment or pose a risk to human health. In addition, if bubbles are generated during pellet production, the surface of the produced pellets may be easily uneven when used to produce a molded product, which may deteriorate the surface condition of the molded product. Therefore, the chlorine content of the packaging material is preferably 0.4 mass% or less, more preferably 0.2 mass% or less, even more preferably 0.1 mass% or less, and particularly preferably 0.05 mass% or less, based on the total mass of the packaging material. The chlorine content of the packaging material can be determined by a method similar to the analytical method for chlorine content described below.

[0025] <Print layer> The printed layer may be a layer that displays any design, pattern, character, symbol, etc., for the purpose of providing decoration or aesthetics; displaying the contents, expiration date, and manufacturer or seller. The printed layer may be a solid printed layer that does not have a design, pattern, character, symbol, etc. The method of forming the printed layer is not particularly limited, and it is preferable to form the printed layer using a printing ink containing a pigment and a binder resin, as described later. The printed layer may have a single layer structure or a multi-layer structure. The thickness of the printed layer is preferably 0.1 to 6 μm, more preferably 0.5 to 4 μm, and particularly preferably 1 to 2.5 μm.

[0026] (Arithmetic mean height Sa value) Furthermore, a packaging material having excellent laminate strength and laminate appearance can be obtained by having the arithmetic mean height Sa value of the printed layer surface be in the range of 2.0 μm or less as specified in ISO 25178. In the present invention, the printed layer surface refers to the surface of the printed layer opposite to the substrate on which printing is performed. The arithmetic mean height Sa of the printed layer surface can be set within the above range by appropriately selecting the solvent composition in the ink, the pigment ratio, additives such as a leveling agent, and by appropriately setting the ink viscosity during printing, the printing speed, the drying temperature, and the pressure conditions of the impression cylinder of the printing press. If the arithmetic mean height Sa is 2.0 μm or less, air bubbles are less likely to be mixed in, and the occurrence of poor appearance and delamination is suppressed. In addition, it is more preferable that the arithmetic mean height Sa is 0.1 μm or more, in which case, the anchor effect of the adhesive is exerted on the printed layer, and the adhesive strength between the printed layer and the adhesive layer is improved. The arithmetic mean height Sa is more preferably 0.3 to 1.5 μm, and even more preferably 0.5 to 1.0 μm.

[0027] The arithmetic mean height Sa of the printed layer surface was measured using a white light interference surface texture measuring instrument (AME Measurements are performed using a Talysurf CCIMP-HS made by TEK Corporation. Measurement and analysis methods are in accordance with ISO 25178.

[0028] (Chlorine content in the printing layer) The chlorine content of the printing layer is preferably 8% by mass or less based on the total mass of the printing layer, since this is environmentally safe and free chlorine is unlikely to be generated. The chlorine content is more preferably 5% by mass or less, even more preferably 3% by mass or less, and particularly preferably 2% by mass or less. In addition, a form in which the chlorine content is 1% by mass or less or 0.5% by mass or less is particularly preferred. The chlorine content of the printed layer can be determined by a method similar to the analytical method for the chlorine content described below.

[0029] (Pigments) The printed layer is preferably formed using a printing ink containing a pigment. Considering the deterioration of quality due to coloring when the packaging material is made into recycled plastic, the content of the colorant in the total mass of the printed layer is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 23% by mass or less. The colorant is preferably a pigment, and the pigment may be any of organic pigments, inorganic pigments, and extender pigments, but inorganic pigments are preferred. As for the pigments, those containing titanium oxide are preferred, and as for the extender pigments, silica, barium sulfate, kaolin, clay, calcium carbonate, magnesium carbonate, etc. are preferred. As for the organic pigments, those made of organic compounds and organometallic complexes are preferred. The pigments may be used alone or in combination of two or more kinds.

[0030] (Organic pigments) Examples of the organic pigment include, but are not limited to, 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.

[0031] The hue of the organic pigment is preferably at least one selected from the group consisting of black pigments, cyan pigments, green pigments, red pigments, purple pigments, yellow pigments, orange pigments, and brown pigments.More preferably, at least one selected from the group consisting of black pigments, cyan pigments, red pigments, and yellow pigments.Specific examples of organic pigments are shown by CI numbers of the Colour Index International (CI). Preferably CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Yellow 83, CI Pigment Yellow 14, CI Pigment Orange 38, CI Pigment Orange 13, CI Pigment Yellow 180, CI Pigment Yellow 139, CI Pigment Red 185, CI Pigment Red 122, CI Pigment Red 178 , CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, CI Pigment Violet 23, CI Pigment Violet 37, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6, CI Pigment Green 7, CI Pigment Orange 34, CI Pigment Orange 64, CI Pigment Black 7.

[0032] (Inorganic pigments) Examples of inorganic pigments include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, titanium oxide, and zinc oxide. Aluminum can be either leafing or non-leafing type, with the non-leafing type being preferred.

[0033] (binder resin) The printed layer is preferably formed using a printing ink containing a binder resin. The binder resin refers to the binding resin in the print layer, and as described below, the chlorine content in the entire binder resin is preferably 5% by mass or less, and more preferably 3% by mass or less or 1% by mass or less.

[0034] Examples of binder resins include, but are not limited to, urethane resins, cellulose resins, polyamide resins, rosin resins, ethylene-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate copolymer resins, vinyl acetate resins, acrylic resins, styrene resins, dammar resins, styrene-maleic acid copolymer resins, polyester resins, alkyd resins, terpene resins, phenol-modified terpene resins, ketone resins, cyclized rubbers, polyvinyl acetal resins, petroleum resins, and modified resins thereof. These resins can be used alone or in combination of two or more kinds, but among the above, it is preferable that the resin does not substantially contain vinyl chloride-vinyl acetate copolymer resins, and it is more preferable that the resin contains a urethane resin.

[0035] Moreover, the binder resin is preferably a thermoplastic resin soluble in an organic solvent. The binder resin is preferably a combination of a resin having a glass transition temperature of -60°C or more and less than 40°C and a resin having a glass transition temperature of 40°C or more and 200°C or less. More preferably, a resin having a glass transition temperature of -50°C or more and 0°C or less and a resin having a glass transition temperature of 50°C or more and 190°C or less are used in combination. In this specification, the glass transition temperature is a measured value in a differential scanning calorimeter (DSC). The resin having a glass transition temperature of -60°C or more and less than 40°C is mainly a urethane resin. The resin having a glass transition temperature of 40°C or more and 200°C is a polyvinyl acetal resin, a cellulose ester resin, a rosin resin, etc., and polyvinyl acetal resin is preferable.

[0036] The printing layer preferably contains 30 to 80 mass %, more preferably 40 to 70 mass %, and even more preferably 50 to 60 mass % of urethane resin or other resin having a glass transition temperature of −60° C. or more and less than 40° C. in its total mass, and preferably contains 1 to 40 mass %, more preferably 5 to 30 mass %, and even more preferably 10 to 20 mass % of polyvinyl acetal resin or other resin having a glass transition temperature of 40° C. or more and 200° C. or less.

[0037] (urethane resin) The binder resin preferably contains a urethane resin. The urethane resin is not particularly limited and is appropriately produced by a known method. A urethane resin made of a polyol and a polyisocyanate, or a urethane resin obtained by reacting a urethane prepolymer of a terminal isocyanate made of a polyol and a polyisocyanate with a polyamine, etc. are preferable. For example, the method described in JP-A-2013-256551 can be mentioned as a production method.

[0038] (Resin L) When the binder resin contains a urethane resin, the binder resin preferably further contains a resin other than the urethane resin (referred to as resin L). Resin L is preferably a resin having a ring structure, more preferably a resin having at least one ring structure selected from the group consisting of an acetal ring structure, an aromatic ring structure, an alicyclic ring structure, and a pyranose ring structure, and even more preferably a resin having an acetal ring structure. These ring structures may have a double bond, or may have an alkyl group or other substituent.

[0039] Resin L contains structural units having a ring structure in an amount of preferably 40 to 95 mass %, and more preferably 50 to 90 mass %, based on the mass of resin L. When the resin L contains a structural unit having a ring structure in the above range, the pigment dispersion in the printing ink is promoted. In addition, the laminate strength of the packaging material is excellent and deterioration over time can be suppressed. Furthermore, blocking resistance is excellent.

[0040] In this specification, the mass of the monomer having a ring structure includes groups substituted or adjacent to the ring structure, such as a methyl group or a nitro group. For example, when resin L is a styrene-acrylic resin and contains 50% by mass of constitutional units derived from α-methylstyrene and 50% by mass of constitutional units derived from butyl methacrylate as an acrylic monomer, the content of the ring structure is 50% by mass.

[0041] The content of the structural unit having a ring structure may be calculated according to the following formula. Formula: Content of structural units having a ring structure (% by mass) = Mass of monomer having ring structure × 100 / Total mass of all monomers constituting resin L

[0042] Examples of resins having a ring structure include polyvinyl acetal resins, cellulose ester resins, rosin resins, polystyrene resins, polyester resins having a ring structure, acrylic resins having a ring structure, and copolymer resins thereof, more preferably those containing at least one selected from the group consisting of polyvinyl acetal resins, cellulose ester resins, and rosin resins, and even more preferably those containing polyvinyl acetal resins.

[0043] (Polyvinyl acetal resin) The polyvinyl acetal resin is an acetal cyclized product of reacting polyvinyl alcohol with an aldehyde such as butyraldehyde and / or formaldehyde, and preferably contains vinyl alcohol units, vinyl acetate units, and an acetal ring group. The polyvinyl acetal resin preferably contains 60 to 90 mass% of acetal rings, 5 to 30 mass% of vinyl alcohol units, and 0.5 to 10 mass% of vinyl acetate units, and is more preferably a polyvinyl butyral resin having a butyral ring as the acetal ring. The weight average molecular weight of the polyvinyl acetal resin is preferably 10,000 to 100,000, and more preferably 10,000 to 80,000.The glass transition point of the polyvinyl acetal resin is preferably 50 to 80°C, and more preferably 60 to 75°C.

[0044] (Cellulose ester resin) The cellulose ester resin is preferably a cellulose acetate alkylate resin, and for example, cellulose acetate propionate and cellulose acetate butyrate are suitably used. The cellulose ester resin preferably has an alkyl group. The alkyl group is preferably an alkyl group having 10 or less carbon atoms, and for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, or a hexyl group is preferably used. The alkyl group may have a substituent. The weight average molecular weight of the cellulose ester resin is preferably 5,000 to 200,000, more preferably 10,000 to 10,000, and further preferably 15,000 to 80,000. The glass transition point of the cellulose ester resin is preferably 120°C to 180°C, and more preferably 130 to 170°C. The combined use of urethane resin and cellulose ester resin improves printability, blocking resistance, and the like.

[0045] (rosin resin) Rosin resin refers to a substance having a structural unit derived from rosin acid (e.g., abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid) as the main component. Here, the main component means 50% by mass or more. The rosin acid or rosin resin may be hydrogenated. The rosin resin is preferably at least one selected from the group consisting of rosin-modified phenolic resins, rosin ester resins, rosin-modified maleic acid resins, and polymerized rosin resins. The acid value of the rosin resin is preferably 350 mgKOH / g or less, more preferably 250 mgKOH / g or less, and further preferably 150 mgKOH / g or less. In one embodiment, the acid value is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less. The softening point of the rosin resin is preferably 60 to 180° C., and more preferably 70 to 150° C. In this specification, the softening point is a value measured by the ring and ball method, and can be measured in accordance with JIS K2207.

[0046] (rosin ester) The rosin resin is preferably a rosin ester, which is an ester condensation resin of a low molecular weight polyol having a molecular weight of 1,000 or less and a rosin acid. The low molecular weight polyol preferably has 2 to 4 hydroxyl groups in one molecule (hereinafter sometimes abbreviated as bifunctional to tetrafunctional) and a molecular weight of 50 to 500. As such a low molecular weight polyol, for example, bifunctional low molecular weight polyols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,10-decanediol, etc.; trifunctional low molecular weight polyols such as glycerin and trimethylolpropane, etc.; and tetrafunctional low molecular weight polyols such as erythritol and pentaerythritol, etc. are preferably used. Among them, trifunctional and / or tetrafunctional low molecular weight polyols are preferred. The weight average molecular weight of the rosin ester is preferably 500 to 2,000, and more preferably 500 to 1,500.

[0047] (Acrylic resin) Acrylic resin has a high affinity with plastic substrates, and by using it as a binder resin, an ink with high adhesion to the substrate can be obtained. In this specification, "acrylic resin" refers to a polymer having an acrylic monomer as a constituent unit. Furthermore, "acrylic monomer" refers to a monomer having an acrylic group or a methacryloyl group, and "methacrylic and acrylic" are sometimes collectively abbreviated as "(meth)acrylic". Furthermore, "methacrylate and acrylate" are sometimes collectively abbreviated as "(meth)acrylate". Acrylic monomers constituting the acrylic resin are listed below, but are not particularly limited. The acrylic monomers may be used alone or in combination of two or more. For example, alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, methylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and methylcyclohexyl (meth)acrylate. Examples of the acrylic monomers containing aromatic rings include 2-ethylhexyl acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate, as well as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. The glass transition temperature (Tg) of the acrylic resin is in the range of 40 to 100°C, preferably 40 to 90°C, and more preferably 40 to 80°C. The weight average molecular weight (Mw) of the acrylic resin is preferably 20,000 to 300,000.

[0048] [Chlorine content of binder resin] The chlorine content of the binder resin is preferably 5% by mass or less, including the case where it is 0. The chlorine content is more preferably 4% by mass or less, further preferably 3% by mass or less, and particularly preferably 2% by mass or less. In addition, an embodiment in which it is 1% by mass or less or 0.5% by mass or less is particularly preferred. The chlorine content is the content (% by mass) of chlorine atoms based on the mass of the binder resin. If the chlorine content is 5% by mass or less, the composition is excellent in environmental safety and is less likely to generate free chlorine.

[0049] The chlorine content can be measured by known methods such as ion chromatography (IC) and ICP mass spectrometry (ICP-MS). Measuring instruments include, for example, LC-20ADsp manufactured by Shimadzu Corporation for IC and Agilent 7700x manufactured by Agilent Technologies for ICP-MS. The chlorine content of the printed layer can be calculated simply from the chlorine content of each raw material constituting the printed layer using the following formula. The same applies to each of the other layers and the entire packaging material. Formula: Chlorine content (%) in total mass of binder resin solids = mass of chlorine in total mass of binder resin solids / total mass of binder resin solids (%) Formula: Chlorine content (%) in total mass of solids in printed layer = mass of chlorine in total mass of solids in printed layer / total mass of solids in printed layer (%)

[0050] In the present invention, the chlorine content is measured in accordance with JIS K0127 (2013). In this measurement method, a sample pretreated by a combustion method is quantified by ion chromatography.

[0051] (Degree of nitrification of binder resin) The binder resin preferably has a degree of nitration of 1% by mass or less, including the case where the degree of nitration is 0. When the degree of nitration is 1% by mass or less, NO X Gas generation can be suppressed, and a safer recycled material can be provided. The degree of nitrification is the degree of esterification of nitric acid ester expressed as the nitrogen content (mass %), and for example, commercially available nitrocellulose usually has a nitrogen content of 10 to 12 mass %. The degree of nitration of the binder resin is more preferably 0.6% by mass or less, further preferably 0.4% by mass or less, and particularly preferably 0.2% by mass or less. When the binder resin contains a urethane resin, the nitrification degree of the urethane resin is preferably 0.3 mass % or less, more preferably 0.2 mass % or less, and further preferably 0.1 mass % or less.

[0052] <Adhesive layer> The adhesive layer in the present invention is a cured product of a solvent-free adhesive. Hereinafter, the solvent-free adhesive may be simply referred to as "adhesive", but this has the same meaning. The solventless adhesive contains a polyol (A) and a polyisocyanate (B), and the shear stress under the following test conditions is preferably 1.5 N or more, more preferably 2.0 N or more, and even more preferably 2.5 N or more. Also, the shear stress is preferably 10.0 N or less, more preferably 7.5 N or less, and even more preferably 5.0 N or less. (Test conditions) A coating amount of 1.9 to 2.1 g / m is applied to the corona-treated surface of a polyethylene terephthalate substrate 1 having a thickness of 25 μm and a wetting tension of 45 to 60 mN / m on the corona-treated surface. 2 An adhesive layer is formed, and the corona-treated surface of substrate 2 having the same thickness and wet tension as substrate 1 is bonded to the substrate 2 so that the bonding area is 25 mm x 25 mm to obtain a test specimen. The test specimen is kept at 20°C and a humidity of 65% for 1 hour, and then a tensile test of substrate 1 and substrate 2 of the test specimen is performed in an environment of 80°C to measure the shear stress. In the present invention, the shear stress is measured five times and the average value is used. As the shear stress measuring device, a general tensile tester can be used.

[0053] More specifically, shear stress refers to the stress that occurs during shear deformation when a film arranged to sandwich an adhesive resin slides in a direction parallel to the surface, and during the lamination process, it occurs in the direction in which the film travels (parallel to the surface). More specifically, when the laminate packaging material passes through any of the impression rolls, coating rolls, nip rolls, and touch rolls equipped in the laminating device, the above-mentioned shear force causes the films to shift, resulting in defects such as air bubbles and delamination. If there are many voids such as delaminations and bubbles in the packaging material, the packaging material is likely to absorb moisture during the cleaning process of the packaging material for material recycling. If the moisture content in the packaging material becomes high, it can cause foaming when producing recycled pellets, which can lead to unevenness on the surface of the molded product. By setting the shear stress to 1.5 N or more, slippage and misalignment between the substrates used in lamination is suppressed, making it possible to maintain the shape immediately after lamination, and when laminating using the solvent-free adhesive, the inclusion of air bubbles and the occurrence of telescoping, etc. can be suppressed.

[0054] The components constituting the solventless adhesive of the present invention will be described in detail below.

[0055] (Polyol (A)) The polyol (A) constituting the solventless adhesive may be a compound having two or more hydroxyl groups, and may be selected from known polyols. Suitable examples of polyols include polyester polyols, polycarbonate polyols, polycaprolactone polyols, polyether polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols. These polyols may be used alone or in combination of two or more. From the viewpoints of leveling ability on a substrate, adhesive performance, and viscosity described below, the polyol (A) preferably contains a polyether polyol and / or a polyester polyol, and more preferably contains a polyether polyol.

[0056] (Polyether polyol) The polyether polyol may be any compound having two or more hydroxyl groups and two or more ether bonds in the molecule, and may be either a bifunctional polyether polyol or a trifunctional polyether polyol. These polyether polyols may be used alone or in combination of two or more. Examples of bifunctional polyether polyols include polyalkylene glycols such as polyethylene glycol, polytrimethylene glycol, polypropylene glycol, polytetramethylene glycol, and polybutylene glycol; polyethylene glycol / polypropylene glycol block copolymers; and propylene oxide / ethylene oxide random polyethers. In addition, an addition polymer obtained by addition polymerization of an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran to a low molecular weight polyol initiator such as water, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, or sucrose may be used as the polyether polyol. Examples of the addition polymer include propylene glycol propylene oxide adducts, glycerin propylene oxide adducts, sorbitol-based propylene oxide adducts, and sucrose-based propylene oxide adducts.

[0057] Examples of trifunctional or higher polyether polyols include aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol; modified polyether polyols obtained by ring-opening polymerization of the above-mentioned aliphatic polyols with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether; and lactone-based polyester polyols obtained by polycondensation reaction of the above-mentioned aliphatic polyols with various lactones such as ε-caprolactone.

[0058] (Polyester polyol) Examples of polyester polyols include polyester polyols obtained by reacting a carboxy group component with a hydroxy group component; and polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone). The carboxy group component is preferably a polyvalent carboxylic acid having primary hydroxyl groups at both ends, and examples thereof include acyclic aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, and fumaric acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic 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; anhydrides or ester-forming derivatives of these aliphatic or aromatic dicarboxylic acids; and polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acid. Among these, from the viewpoint of reactivity, the carboxy group component is preferably one containing a non-cyclic aliphatic dicarboxylic acid, more preferably one containing adipic acid.

[0059] The hydroxyl group component is preferably a polyhydric alcohol having primary hydroxyl groups at both ends, and examples of the polyhydric alcohol include diols and polyols having three or more functional groups. Examples of the diol include aliphatic diols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3,3'-dimethylolheptane, and 1,4-bis(hydroxymethyl)cyclohexane; ether glycols such as polytetramethylene ether glycol and polyoxyethylene glycol; modified polyether diols obtained by ring-opening polymerization of the aliphatic diols with various cyclic ether bond-containing compounds such as ethylene oxide and tetrahydrofuran; lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic diols with various lactones such as lactanoids and ε-caprolactone; and alkylene oxide adducts of bisphenols obtained by adding ethylene oxide or the like to bisphenols such as bisphenol A and bisphenol F.

[0060] Examples of the tri- or higher functional polyols include aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol; modified polyether polyols obtained by ring-opening polymerization of the aliphatic polyols with various cyclic ether bond-containing compounds such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and allyl glycidyl ether; and lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic polyols with various lactones such as ε-caprolactone. Among these, from the viewpoint of reactivity, the polyhydric alcohol is preferably one containing an aliphatic diol, and more preferably one containing diethylene glycol.

[0061] The carboxyl group components and hydroxyl group components constituting these polyester polyols may each be used alone or in combination of two or more.

[0062] Preferred embodiments of the polyol (A) are further described below.

[0063] The polyol (A) may be an acid-modified product in which some of the hydroxyl groups in the polyol are acid-modified, and may be a product in which some of the hydroxyl groups in the polyol are reacted with an acid anhydride to introduce carboxyl groups. Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic ester anhydride. Examples of the trimellitic ester anhydride include ester compounds obtained by esterifying an alkylene glycol or alkanetriol having 2 to 30 carbon atoms with trimellitic anhydride, and specific examples thereof include ethylene glycol bisanhydrotrimellitate, propylene glycol bisanhydrotrimellitate, and the like.

[0064] The polyol (A) may be a urethane polyol in which a urethane bond is introduced by reacting a part of the hydroxyl groups in the polyol with an isocyanate compound. Examples of the isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, hexamethylene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

[0065] When the polyether polyol or polyester polyol is modified with the polyisocyanate to obtain a urethane polyol, the molar equivalent ratio of the number of moles of isocyanate groups to the number of moles of hydroxyl groups (NCO moles / OH moles) is preferably 0.20 to 0.40, more preferably 0.30 to 0.35. When the molar equivalent ratio is 0.20 or more, a polymer with a larger molecular weight is obtained, and the adhesive strength of the adhesive is improved, which is preferable. When the molar equivalent ratio is 0.40 or less, the pot life of the adhesive is improved, which is preferable.

[0066] The polyol (A) in the present invention is preferably a polyether-based urethane polyol obtained by modifying a polyether polyol with a polyisocyanate. The use of a polyether-based urethane polyol is preferred because it provides an appropriate level of flexibility and crosslinking density in the adhesive, improves adhesive strength, and provides good coating suitability.

[0067] The number average molecular weight of the polyol (A) is preferably 300 to 3,000, more preferably 500 to 2,000. When the number average molecular weight is 300 or more, the toughness of the polymer in the adhesive increases, and the adhesive strength is improved, which is preferable. When the number average molecular weight is 3,000 or less, the compatibility with the resin is improved, which is preferable. In this specification, the number average molecular weight and weight average molecular weight are values ​​measured using GPC (gel permeation chromatography) manufactured by Showa Denko KK, using tetrahydrofuran as a solvent, and converted into standard polystyrene.

[0068] The hydroxyl value of the polyol (A) is preferably 100 to 200, more preferably 120 to 180. A hydroxyl value of 100 or more is preferable because it gives a good crosslinking density and improves the adhesive strength. A hydroxyl value of 200 or less is preferable because it improves the coating suitability.

[0069] In synthesizing the polyether-based urethane polyol, it is preferable to use a trifunctional polyol raw material, and in this case, the content of the trifunctional polyol raw material relative to the total amount of the polyol raw material is preferably 4.0 mass% or more and 12.0 mass% or less, more preferably 5.0 mass% or more and 10.0 mass% or less, and even more preferably 5.0 mass% or more and 8.5 mass% or less. If it is 4.0 mass% or more, crosslinking is efficiently formed, shear stress is improved, and air bubble inclusion and telescoping are suppressed, which is preferable. If it is 12.0 mass% or less, flexibility is improved and adhesive strength is improved, which is preferable.

[0070] (Polyisocyanate (B)) The polyisocyanate (B) constituting the solventless adhesive is not particularly limited, but is preferably one having a urethane bond, and more preferably a polyester polyol which is a reaction product of a polyester polyol and / or a polyether polyol with a polyisocyanate. Preferably, the adhesive is a polyetherurethane polyisocyanate and / or a polyetherurethane polyisocyanate. More preferably, the adhesive contains a polyetherurethane polyisocyanate. By containing a polyetherurethane polyisocyanate, the adhesive can have both flexibility and crosslink density, improve shear stress and adhesive strength, and further have a suitable viscosity, which will be described later.

[0071] (Polyester polyol) The polyester polyol may be any compound having two or more hydroxyl groups and two or more ester bonds in the molecule, and those described in the above section on (Polyol (A)) above may be suitably used.

[0072] (Polyether polyol) The polyether polyol may be any compound having two or more hydroxyl groups and two or more ether bonds in the molecule, and those described in the section on (Polyol (A)) above can be suitably used. The use of polyether polyol is preferred because it makes the coating film of the adhesive flexible and improves the adhesive strength. Among them, from the viewpoint of coating film flexibility and resin compatibility, the polyether polyol is preferably a polyether polyol having a molecular weight of 400 to 2,000. A molecular weight of 400 or more is preferable because the flexibility of the polymer chain in the adhesive increases. A molecular weight of 2,000 or less is preferable because the compatibility with the isocyanate component improves and the urethane reaction easily proceeds.

[0073] When the polyisocyanate (B) contains a polyether urethane polyisocyanate, the ratio of the number of moles of isocyanate groups to the number of moles of hydroxyl groups (NCO moles / OH moles) when the polyether polyol is reacted with the polyisocyanate described later to obtain the polyether urethane polyisocyanate is preferably 3.0 or more and less than 4.0, and preferably 3.3 or more and less than 3.6. If the molar equivalent ratio is 3.0 or more, the crosslinking speed is improved, which is preferable. If the molar equivalent ratio is less than 4.0, a polyether urethane polyisocyanate with a higher molecular weight is obtained, which is preferable because the shear stress and adhesive strength of the adhesive are improved.

[0074] Examples of the isocyanate compound used in the polyisocyanate (B) include aromatic isocyanates, araliphatic isocyanates, aliphatic isocyanates, alicyclic isocyanates, and modified products thereof. These isocyanate compounds may be used alone or in combination of two or more.

[0075] Examples of the aromatic isocyanate include aromatic diisocyanates such as diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; and aromatic isocyanates such as polymethylene polyphenyl polyisocyanate. Examples of the araliphatic isocyanate include araliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof. Examples of the aliphatic isocyanate include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methylcaproate, lysine diisocyanate, and dimer acid diisocyanate. Examples of the alicyclic isocyanate include alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, and norbornene diisocyanate.

[0076] Examples of modified isocyanate compounds include allophanate type modified compounds, isocyanurate type modified compounds, biuret type modified compounds, adduct type modified compounds, and also reaction products having an isocyanate group and a urethane bond, which are obtained by reacting the above-mentioned isocyanate compounds with polyols under conditions of an excess of isocyanate groups. The polyol that forms the modified product of the isocyanate compound is not particularly limited and can be selected from known polyols, such as polyester polyols, polyester urethane polyols, polycarbonate polyols, polycaprolactone polyols, polyether polyols, polyether urethane polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols.

[0077] From the viewpoint of improving the shear stress of the adhesive and the adhesion to the substrate, these isocyanate compounds are preferably aromatic isocyanates, and more preferably those containing diphenylmethane diisocyanate. The diphenylmethane diisocyanate may be either 4,4'-diphenylmethane diisocyanate or 2,4-diphenylmethane diisocyanate. That is, the polyisocyanate (B) preferably contains a polyester polyurethane polyisocyanate and / or a polyether urethane polyisocyanate which is a reaction product of a polyester polyol and / or a polyether polyol with an aromatic isocyanate.

[0078] The isocyanate group content of the polyisocyanate (B) is preferably in the range of 10.0 to 12.0, more preferably 10.5 to 11.5. When the isocyanate group content of the polyisocyanate (B) is in the above range, it is preferable because an appropriate crosslinking density is formed and the adhesive strength is improved.

[0079] In the solventless adhesive, the blending ratio of polyol (A) and polyisocyanate (B) is preferably such that the reaction equivalent ratio [NCO / OH] between the total isocyanate groups of the polyisocyanate (B) and the total hydroxyl groups of the polyol (A) is in the range of 1.0 to 2.0, more preferably 1.0 to 1.5, from the viewpoint of obtaining a suitable viscosity, etc. Also, the blending amount of polyol (A) is preferably 30 to 100 mass %, more preferably 40 to 70 mass %, based on the total polyisocyanate, from the viewpoint of adhesive performance.

[0080] (viscosity) In one embodiment, the solventless adhesive preferably has a viscosity of 100 to 10,000 mPa·s, more preferably 300 to 5,000 mPa·s, measured in accordance with JIS K5600-2-3 at 20°C to 120°C immediately after mixing the polyol (A) and the polyisocyanate (B) (for example, within 1 minute after mixing). If the viscosity is 100 mPa·s or more, the adhesive has excellent initial cohesive strength, which is preferable. If the viscosity is 10,000 mPa·s or less, the adhesive has excellent coatability, which is preferable. Furthermore, the viscosity at 40°C measured in accordance with JIS K5600-2-3 immediately after mixing polyol (A) and polyisocyanate (B) at 40°C is 500 to 4000 mPa s It is preferable that the viscosity is within a range of 1000 to 3000 mPa·s.

[0081] In one embodiment, the solventless adhesive has a viscosity at 40°C measured in accordance with JIS K5600-2-3 after mixing the polyol (A) and the polyisocyanate (B) at 40°C and then leaving the mixture at rest for 20 minutes at 40°C of preferably 6000 mPa·s or less, more preferably 5,000 mPa·s or less, further preferably 4,000 mPa·s or less, and particularly preferably 3,500 mPa·s or less. It is preferable that the viscosity (ICI viscosity) measured in accordance with JIS K5600-2-3 at 40°C is 6,000 mPa·s or less, as this allows the adhesive to be used for long periods of time without excessive thickening and improves its suitability for application.

[0082] (Other ingredients) The solventless adhesive may contain other components in addition to those described above in order to satisfy various physical properties required for the adhesive or packaging material. These other components may be blended with either the polyol (A) or the polyisocyanate (B), or may be added when blending the polyol (A) and the polyisocyanate (B). These other components may be used alone or in combination of two or more. Examples of the other components include reaction accelerators, leveling agents, defoamers, silane coupling agents, phosphoric acid or phosphoric acid derivatives, inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.), rust inhibitors, thickeners, plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, crystal nucleating agents, and catalysts for adjusting the curing reaction.

[0083] (Silane coupling agent) The solventless adhesive may contain a silane coupling agent from the viewpoint of improving the adhesive strength to metal-based materials such as inorganic vapor deposition layers and metal foils. Examples of the silane coupling agent include trialkoxysilanes having a vinyl group such as vinyltriethoxysilane and vinyltriethoxysilane; trialkoxysilanes having an amino group such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; trialkoxysilanes having a glycidyl group such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. The content of the silane coupling agent is preferably 0.1 to 5 mass %, more preferably 0.2 to 3 mass %, based on the mass of the polyol (A). By setting the content of the silane coupling agent within the above range, it is possible to improve the adhesive strength to metal materials such as inorganic vapor deposition layers and metal foils.

[0084] (Phosphoric acid or phosphoric acid derivatives) The solventless adhesive may contain phosphoric acid or a phosphoric acid derivative from the viewpoint of improving adhesive strength to inorganic vapor deposition layers and metal materials such as metal foils. The phosphoric acid may be any phosphoric acid having at least one free oxygen acid, and examples of the phosphoric acid include phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and hypophosphoric acid; and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of phosphoric acid derivatives include those obtained by partially esterifying the above phosphoric acid with alcohols while leaving at least one free oxygen acid. Examples of the alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin; and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol. The content of phosphoric acid or a derivative thereof is preferably 0.01 to 10 mass%, more preferably 0.05 to 5 mass%, and particularly preferably 0. 05 to 1 mass%.

[0085] <Base material> The substrate is preferably in the form of a film or sheet for use as a packaging material, and preferably contains a polyolefin resin. Furthermore, the polyolefin resin is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more of the total mass of the base material. Moreover, the polyolefin resin is more preferably a polypropylene-based resin and / or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a copolymer of ethylene and / or butene.

[0086] The substrate containing polyolefin resin may be simply a laminate of substrates made of polyolefin resin, or a substrate different from a substrate made of polyolefin resin may be laminated via adhesion or the like. The "substrate different from the substrate made of polyolefin resin" may be a film having properties different from the substrate made of polyolefin resin, and may be of any type. In addition, in the case of a laminated substrate, it may be in a form including an adhesive layer. The method of laminating the substrates is not particularly limited, and may be a conventionally known method such as coextrusion, heat fusion, and pressure bonding via an adhesive layer.

[0087] The substrate made of the polyolefin resin has higher resistance to alkaline aqueous solutions and heat during the molding process than the ester substrate, and is less susceptible to thermal decomposition and hydrolysis, so that the molecular weight can be maintained high during recycling. Furthermore, from the viewpoint of ease of recovery after recycling, examples of the polyolefin substrate include polyethylene such as biaxially oriented polypropylene (OPP), non-oriented polypropylene (CPP), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), acid-modified polyethylene, acid-modified polypropylene, copolymer polypropylene, and films laminated with these. The thickness of the substrate is not particularly limited, and is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 70 μm or less, in consideration of processability into packaging containers. Among them, a film having heat sealability is preferably used, and CPP, heat sealable OPP, etc. correspond to them.

[0088] The substrate is preferably a gas barrier substrate, for example, a plastic substrate having an inorganic vapor deposition layer of aluminum, silica, alumina, or the like; or a plastic substrate having an organic layer of an ethylene-vinyl alcohol copolymer, polyvinyl alcohol, or the like.

[0089] The substrate is preferably in a form containing additives such as antistatic agents, antifogging agents, and ultraviolet protection agents (coated or kneaded), in a form having an easily adhesive coating layer (e.g., a layer containing polyvinyl alcohol and its derivatives), in a form in which the surface of the substrate is corona-treated or low-temperature plasma-treated, etc. The above-mentioned additions and processing are also carried out for the purpose of improving the wettability of printing inks and other coating agents, or for the purpose of imparting specific functionality to the film, and are suitably used, for example, to provide a packaging material with excellent visibility of the contents by preventing the packaging material from fogging due to moisture.

[0090] <Intermediate substrate> The packaging material of the present invention may further have an intermediate substrate, and the intermediate substrate preferably contains a polyolefin resin. Furthermore, the polyolefin resin preferably accounts for 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more, of the total mass of the intermediate substrate. preferable. Moreover, the polyolefin resin is more preferably a polypropylene-based resin and / or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and / or butene. Examples of intermediate substrates include polyolefin resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer, propylene homopolymer, and ethylene-propylene copolymer. Gas barrier substrates, for example, plastic substrates having an inorganic vapor deposition layer of aluminum, silica, alumina, or the like, or plastic substrates having a layer of a mixture of organic and inorganic components, are preferred.

[0091] <Sealant> The inner layer of the sealant is in direct contact with the packaged item and serves to protect the packaged item. In order to form the laminate into a bag, it is preferable that the innermost layer of the sealant has heat sealability. The sealant preferably contains a polyolefin resin. Furthermore, of the total mass of the sealant, the polyolefin resin preferably accounts for 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, even more preferably 80 mass% or more, and particularly preferably 90 mass% or more. Moreover, the polyolefin resin is more preferably a polypropylene-based resin and / or a polyethylene-based resin, further preferably a polypropylene-based resin, and particularly preferably a polypropylene-based resin that is a copolymer with ethylene and / or butene. Examples of materials constituting the sealant include polyolefin resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer, propylene homopolymer, and ethylene-propylene copolymer, and one or more of these resins can be used. The sealant may be composed of a single layer or may be composed of two or more layers. Note that the sealant is preferably a non-stretched film made of the above-mentioned resin in order to suppress shrinkage during heat sealing.

[0092] The thickness of the sealant is not particularly limited and is appropriately set depending on the application of the laminate and the type and properties of the packaged goods, but is usually preferably 10 to 200 μm. In addition, in the case of a pouch (particularly a retort pouch), the thickness of the sealant is preferably 20 to 150 μm, more preferably 25 to 130 μm.

[0093] The sealant may be a sealant having an inorganic layer such as aluminum, silica, and alumina, or an organic layer such as ethylene-vinyl alcohol copolymer, polyvinyl alcohol, etc. It may also be a composite substrate by coextrusion or a blended opalescent substrate such as a pigment.

[0094] (Manufacturing method of packaging materials) The method for producing a packaging material of the present invention is a method for producing a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant in this order, and containing 80% by mass or more of a polyolefin resin, and the substrate has a surface having an arithmetic mean height Sa value of 2.0 μm or less as specified in ISO 25178. The method includes a step of forming a print layer and a step of applying a solventless adhesive containing a polyol (A) and a polyisocyanate (B). The adhesive layer may be applied to the print layer and laminated, or may be applied to a sealant and laminated. As a preferred embodiment, For example, the embodiment includes a step of applying an adhesive onto the printed layer and then laminating a sealant. When the packaging material further includes an intermediate substrate layer, a preferred embodiment includes a step of laminating the printed layer and the intermediate substrate layer with an adhesive, and then laminating the intermediate substrate layer and the sealant. The configuration is arbitrary and is not particularly limited.

[0095] The packaging material thus obtained can be cut to a predetermined size, and the edges of the packaging material can be heat-sealed with the sealants joined together to form a bag. The heat-sealing temperature is preferably 50 to 250°C, more preferably 80 to 180°C. The heat-sealing pressure is 1 to 5 kg / cm. 2 The conditions are as follows. One sheet of packaging material may be folded and the edges may be heat sealed, or two or more sheets of packaging material may be heat sealed. Also, a bag made of packaging material may be one in which all openings are heat sealed after the contents are packed. EXAMPLES

[0096] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the present invention, parts and % represent parts by mass and % by mass unless otherwise noted.

[0097] (Hydroxyl value) The hydroxyl value is the number of milligrams of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl group when 1 g of a sample is acetylated, and was measured according to the method described in JIS K0070.

[0098] (Acid value) The acid value is the number of milligrams of potassium hydroxide required to neutralize the free fatty acids, resin acids, etc. contained in 1 g of a sample, and was measured by the method described in JIS K0070.

[0099] (amine value) The amine value is the equivalent amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of sample. The amount of potassium hydroxide is measured in milligrams in accordance with JIS K0070. That is, 0.5 to 2 g of sample was precisely weighed out (sample solid content: Sg). 50 mL of a mixed solution of methanol / methyl ethyl ketone = 60 / 40 (mass ratio) was added to the precisely weighed sample to dissolve it. Bromophenol blue was added to the obtained solution as an indicator, and the obtained solution was titrated with 0.2 mol / L ethanolic hydrochloric acid solution (titer: f). The point at which the color of the solution changed from green to yellow was set as the end point, and the titration amount (A mL) at this point was used to calculate the amine value according to the following formula. (Formula) Amine value = (A x f x 0.2 x 56.108) / S [mgKOH / g]

[0100] (Weight average molecular weight, number average molecular weight) The weight average molecular weight and number average molecular weight were determined by measuring the molecular weight distribution using a gel permeation chromatography (GPC) device (HLC-8220 manufactured by Tosoh Corporation) and calculating the molecular weight converted using polystyrene as a standard substance. The measurement conditions are shown below. Columns: The following columns were used in series connection: Tosoh Corporation TSKgel Super AW2500 Tosoh Corporation TSKgel Super AW3000 Tosoh Corporation TSKgel Super AW4000 Tosoh Corporation's TSK gelguard column Super AWH Detector: RI (differential refractometer) Measurement conditions: Column temperature 40℃ Eluent: Tetrahydrofuran Flow rate: 1.0mL / min

[0101] (Glass transition temperature (Tg)) The glass transition point was determined by differential scanning calorimetry (DSC). The measurement was performed using a Rigaku Corporation DSC8231 under conditions of a measurement temperature range of -70 to 250°C and a heating rate of 10°C / min. The midpoint (inflection point) of the baseline shift based on the glass transition in the DSC curve was taken as the glass transition point.

[0102] (Chlorine content) The chlorine content was measured in accordance with JIS K0127 (2013). That is, the ink or binder resin was applied to a transparent substrate to a thickness of 2.0 μm to form a coating film. It was dried at 80°C and 0.5 g was scraped off. The scraped coating film was pretreated by the combustion method, and the chlorine content of the obtained sample was quantified by ion chromatography to determine the chlorine content.

[0103] (Method of measuring NCO content) Approximately 1 g of sample was weighed out into a 200 mL Erlenmeyer flask, and 10 mL of 0.5 N di-n-butylamine in toluene solution and 10 mL of toluene were added to dissolve the sample. Next, phenolphthalein test solution was added as an indicator, and after holding for 30 seconds, the solution was titrated with 0.25 N hydrochloric acid solution until it turned a pale pink color. The NCO content (mass%) was calculated using the following formula: NCO (mass%) = {(ba) x 4.202 x F x 0.25} / S S: Amount of sample collected (g) a: Consumption of 0.25N hydrochloric acid solution (ml) b: Amount of 0.25N hydrochloric acid solution consumed in the blank experiment (ml) F: Potency of 0.25N hydrochloric acid solution

[0104] (ICI viscosity) The ICI viscosity was measured in accordance with JIS K 5600-2-3 using a "CV-1S" made by Toa Kogyo Co., Ltd. Specifically, a drop of the solvent-free adhesive was placed with a glass rod on the plate of the machine, which was set to 40°C, either immediately after mixing or 20 minutes after mixing, and the cone was lowered and rotation was started, and the value (mPa s) at which the adhesive stabilized was used.

[0105] (shear stress) The shear stress of the solvent-free adhesive was measured as follows. <1> Polyol (A) and polyisocyanate (B) were mixed and applied in an amount of 2.0 g / m onto a polyethylene terephthalate film having a thickness of 25 μm and a wetting tension of 45 to 60 mN / m. 2After coating with the solution, the polyethylene terephthalate film is laminated to a width of 25 mm and stored in an environment of 20°C and 65% RH for 1 hour. <2> After storage, a test piece with a bonding area of ​​25 mm × 25 mm was prepared, and the shear stress was measured using the test piece in a tensile test in an environment of 80° C. The tensile test was performed at a tensile speed of 30 cm / min. The above measurement was carried out five times, and the average value was used.

[0106] (arithmetic mean height Sa) The arithmetic mean height Sa of the printed layer surface is measured using a white light interference surface texture measuring instrument (e.g., AMETE Measurements were made using a Talysurf CCIMP-HS from Ametech Co., Ltd. The film was cut into a measurement sample of an arbitrary size, approximately 2 cm square, and after thoroughly smoothing out any wrinkles, it was set on the measurement stage using an electrostatic contact plate or similar. A 5x objective lens was used for measurements, measuring one field of view (1024 x 1024 pixels / 3.17 mm x 3.17 mm), and this operation was carried out at 10 points at 5 mm intervals in the machine direction from the center in both the machine and width directions on the surface of the printed layer of the target sample film. Next, the obtained data was For the non-measurement points, noise was removed, followed by leveling using the least squares method and shape removal using a polynomial, and then waviness was removed using a robust Gaussian filter (cutoff value 0.25 mm). This makes it possible to properly measure the state of the surface of the printed layer. Next, the analysis software "Talimap" was used to determine the Sa value (μm) using an analysis method compliant with ISO25178, and the average value of each value obtained at the above 10 points was calculated.

[0107] <Synthesis of urethane resin> (Synthesis Example 1) Urethane resin PU1 A condensation product of 3-methyl-1,5-pentanediol (MPD) and sebacic acid (SA), a polyester polyol having a number average molecular weight of 2,000 (hereinafter referred to as "MPD / SA"), 100 parts of 1,4-butanediol (hereinafter referred to as "1,4-BD"), 28.5 parts of isophorone diisocyanate (hereinafter referred to as "IPDI"), and 32.1 parts of ethyl acetate were mixed and reacted at 90°C for 5 hours under a nitrogen atmosphere to obtain a urethane prepolymer with a terminal isocyanate. Next, 11.0 parts of isophoronediamine (hereinafter "IPDA"), 1.0 part of N-(2-aminoethyl)ethanolamine (hereinafter "AEA"), 1.0 part of dibutylamine (hereinafter "DBA"), and 300.4 parts of mixed solvent 1 (ethyl acetate / isopropanol (IPA) = 70 / 30 (mass ratio)) were stirred and mixed, and the obtained urethane prepolymer with terminal isocyanate was gradually added at 40 °C. The reaction was carried out at 80° C. for 1 hour to obtain a solution of urethane resin PU1 having a solid content of 30 mass %, an amine value of 6.5 mg KOH / g, a hydroxyl value of 3.8 mg KOH / g, and a weight average molecular weight of 50,000. The chlorine content of urethane resin PU1 was 0 mass %.

[0108] (Synthesis Example 2) Urethane resin PU2 30 parts of polyester polyol having a number average molecular weight of 2,000, which is a condensation product of neopentyl glycol (NPG) and adipic acid (AA), 70 parts of polypropylene glycol (PPG1000) having a number average molecular weight of 1,000, 3 parts of 1,4-butanediol, 42.0 parts of isophorone diisocyanate, and 35.5 parts of ethyl acetate were mixed and reacted at 90°C for 5 hours in a nitrogen atmosphere to obtain a urethane prepolymer with a terminal isocyanate. Next, 16.0 parts of isophoronediamine, 1.0 part of N-(2-aminoethyl)ethanolamine, 1.0 part of dibutylamine, and 345.0 parts of mixed solvent 1 (ethyl acetate / isopropanol=70 / 30 (mass ratio)) were stirred and mixed, and the obtained urethane prepolymer with terminal isocyanate was gradually added at 40°C. The reaction was carried out at 80° C. for 1 hour to obtain a solution of urethane resin PU2 having a solid content of 30 mass %, an amine value of 5.2 mg KOH / g, a hydroxyl value of 3.3 mg KOH / g, and a weight average molecular weight of 40,000. The chlorine content of urethane resin PU2 was 0 mass %.

[0109] The compounding compositions and properties of urethane resins PU1 and PU2 are shown in Table 1.

[0110] [Table 1]

[0111] In the following ink preparation examples, the following materials were used: PVB solution: A 30% solids solution of polyvinyl butyral resin (glass transition point 70°C, weight average molecular weight 50,000, chlorine content 0% by mass, degree of nitration 0% by mass) having vinyl alcohol units, vinyl acetate units, and vinyl butyral units and containing 73% by mass of butyral ring groups in a 1 / 1 ethyl acetate / isopropanol mixed solvent. PVC solution: vinyl chloride-vinyl acetate copolymer resin (Solvin TA3, manufactured by Nissin Chemical Co., Ltd.) Chlorine content 47.1% by mass, nitrification rate 0% by mass, 30% solids in ethyl acetate solution

[0112] <Ink preparation> [Ink Preparation Example 1] Ink X1 40 parts of urethane resin PU1 solution, 15 parts of polyvinyl butyral resin (PVB) solution, 5 parts of CI pigment blue 15:3 (manufactured by Toyo Color Co., Ltd., product name: LIONOLBLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2A pigment dispersion was obtained by mixing 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water with a bead mill, and the resulting pigment dispersion was mixed with stirring to obtain an organic solvent-based ink X1.

[0113] [Ink Preparation Example 2] Ink X2 40 parts of urethane resin PU1 solution, 10 parts of polyvinyl butyral resin (PVB) solution, 10 parts of CI pigment blue 15:3 (manufactured by Toyo Color Co., Ltd., product name: LIONOLBLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), 10 parts of silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 0.8 parts of 100% ethyl acetate / g) and 33.4 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed, and the bicarbonate was Dispersion was performed for 20 minutes using a feed mill to obtain a pigment dispersion. The obtained pigment dispersion was mixed with 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0°C), and 1.5 parts of water by stirring to obtain an organic solvent-based ink X2.

[0114] [Ink Preparation Example 3] Ink X3 40 parts of urethane resin PU1 solution, 8 parts of polyvinyl butyral resin (PVB) solution, 2 parts of vinyl chloride-vinyl acetate solution (PVC) solution, 10 parts of CI Pigment Yellow 14 (chlorine content 10.8% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 0.8 parts of ethyl alcohol / g) and 33.4 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed for 20 minutes with a bead mill to obtain a pigment dispersion. 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0 ° C.), and 1.5 parts of water were mixed and stirred to obtain organic solvent-based ink X3.

[0115] [Ink Preparation Example 4] Ink X4 40 parts of urethane resin PU2 solution, 15 parts of polyvinyl butyral resin (PVB) solution, 5 parts of CI pigment blue 15:3 (manufactured by Toyo Color Co., Ltd., product name: LIONOLBLUE FG-7330, chlorine content 0% by mass, nitrification degree 0% by mass), silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 0.8 parts of ethyl alcohol / g) and 33.4 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed for 20 minutes with a bead mill to obtain a pigment dispersion. 0.8 parts of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0 ° C.), and 1.5 parts of water were mixed and stirred to obtain organic solvent-based ink X4.

[0116] Table 2 shows the compositions and properties of the organic solvent-based inks X1 to X4.

[0117] [Table 2]

[0118] (Production method of polyol (A)) (Synthesis of polyol (A) A1) A reaction vessel equipped with a stirrer, a temperature control system, a reflux condenser, a dropping tank, and a nitrogen gas inlet tube was charged with 84.4% triol having a number average molecular weight of about 400, which is made by adding polypropylene glycol to glycerin. The mixture was stirred under a nitrogen gas flow while heating at 80°C to 90°C for 3 hours to carry out a urethane reaction, and a polyol (A) A1 having a urethane bond was obtained.

[0119] (Synthesis of polyol (A) A2) A reaction vessel equipped with a stirrer, a temperature control system, a reflux condenser, a dropping tank and a nitrogen gas inlet tube was charged with 94.8 parts of adipic acid, 65.6 parts of sebacic acid, 269.5 parts of terephthalic acid, 60.4 parts of ethylene glycol and 309.7 parts of diethylene glycol, and heated to 260°C while stirring under a nitrogen stream. After the reaction was continued until the acid value was 5 or less, the pressure was gradually reduced, and the reaction was continued at 1 mmHg to remove excess alcohol, thereby obtaining a polyol (A) A2 with a hydroxyl value of 60 mgKOH / g. The composition and properties of the polyol (A) A2 are shown in Table 3.

[0120] [Table 3]

[0121] (Synthesis of polyols (A) A3 to A6) Except for changing the raw materials and amounts thereof as shown in Table 4, a urethane-forming reaction was carried out in the same manner as in Polyol (A) A1, to obtain Polyols (A) A3 to A6 having urethane bonds.

[0122] [Table 4]

[0123] <Production of Polyisocyanate (B)> (Synthesis of polyisocyanate (B) B1) A reaction vessel equipped with a stirrer, a temperature control system, a reflux condenser, a dropping tank and a nitrogen gas inlet tube was charged with 371.0 parts of a mixture of 2,4-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate (mass ratio 50:50), 27.4 parts of a triol having a number average molecular weight of about 400 in which polypropylene glycol was added to glycerin, 2.6 parts of trimethylolpropane, 31.8 parts of polypropylene glycol having a number average molecular weight of about 400, 289.4 parts of polypropylene glycol having a number average molecular weight of about 2,000, and 77.8 parts of polytetramethylene glycol having a number average molecular weight of about 1,000. The mixture was heated at 80°C to 90°C for 3 hours while stirring under a nitrogen gas stream to carry out a urethane reaction, and a polyisocyanate (B) B1 having a urethane bond and an isocyanate group content of 11.1% was obtained.

[0124] (Synthesis of Polyisocyanates (B) B2 to B6) Except for changing the raw materials and amounts thereof as shown in Table 5, a urethane-forming reaction was carried out in the same manner as for polyisocyanate (B) B1, to obtain polyisocyanates (B) B2 to B6 having urethane bonds.

[0125] [Table 5]

[0126] In the following examples and comparative examples, the following were used: OPP: One-sided surface corona discharge treatment biaxially oriented polypropylene film (thickness 20 μm) PET: One-sided surface corona discharge treatment Biaxially oriented polyethylene terephthalate film (thickness 12 μm) CPP: One-sided surface corona discharge treatment non-oriented polypropylene film (thickness 30μm)

[0127] [Example 1] (Preparation of packaging material C1) The ink X1 was diluted and adjusted with a propyl acetate / IPA mixed solvent (mass ratio 70 / 30) to a Zahn cup #3 (manufactured by Rigo Co., Ltd.) viscosity of 15 seconds (at 25°C), and printed on the corona-treated surface of an OPP film at a printing speed of 150 m / min using a gravure printing machine equipped with a gravure plate with a plate depth of 35 μm, and dried at 50°C to obtain an arithmetic mean height Sa value of the printed surface of 0.8 μm. After drying the printed layer, the coating amount was 2.5 g / m 2 It was decided. Next, polyol (A) A1 and polyisocyanate (B) B1 are mixed at 40°C. A solvent-free adhesive was obtained. Using a laminator in a room temperature environment, the corona-treated surface of a 30 μm-thick CPP film and the printed surface obtained above were laminated with the solvent-free adhesive in an application amount of 2.0 g / m. 2 After laminating 3000 m at a lamination speed of 200 m / min, the adhesive was completely cured by keeping at 40° C. for 2 days to obtain a packaging material C1 having a structure of OPP / printed layer / adhesive layer / CPP.

[0128] [Examples 4 to 11] (Packaging Materials C4 to C11) In the same manner as in Example 1, packaging materials C4 to C11 were obtained according to the raw materials and blending amounts shown in Table 6. The unit of Sa value in Table 6 is μm.

[0129] [Comparative example 1] (Packaging material D1) The viscosity of Ink X2 in Zahn cup #3 (manufactured by Rigo Co., Ltd.) was adjusted to 18 seconds (at 25°C) using a propyl acetate / IPA mixed solvent (mass ratio 70 / 30), and the ink was printed on the corona-treated surface of an OPP film at a printing speed of 200 m / min using a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm, and dried at 50°C to obtain a printed matter (OPP) with an arithmetic mean height Sa value of the printed surface of 2.2 μm. After drying of the printed layer, the coating amount was 2.5 g / m 2 It was decided. Next, polyol (A) A1 and polyisocyanate (B) B1 were mixed at 40°C in a mass ratio of (A) / (B) = 50 / 100 to obtain a solventless adhesive. Using a laminator in a room temperature environment, the corona-treated surface of a 30 μm-thick CPP film and the printed surface obtained above and the solventless adhesive were applied in an amount of 2.0 g / m 2 After laminating 3000 m at a lamination speed of 200 m / min, the adhesive was completely cured by keeping at 40° C. for 2 days to obtain a packaging material D1 having a structure of OPP / printed layer / adhesive layer / CPP.

[0130] [Comparative example 2] (Packaging material D2) Except for changing the substrate to a PET film, packaging material D2 having a structure of PET / printed layer / adhesive layer / CPP was obtained in the same manner as in Example 1 using the raw materials and their blending amounts shown in Table 6.

[0131] (Laminate appearance evaluation) The wound rolls of the packaging material of about 3000 m obtained in the above examples and comparative examples were visually observed to see at what distance from the start of winding the film would telescope and demination occur, and were evaluated according to the following criteria. Note that telescope refers to the film slipping in the shear direction during winding, causing misalignment and resulting in the roll becoming bamboo shoot-like. The evaluation results are shown in Table 6. A (Excellent): No telescoping or delamination B (Good): No telescoping or delamination below 2500m, telescoping or delamination above 2500m C (Acceptable) No telescoping or delamination at less than 2000m, telescoping or delamination at 2000m or more D (Not acceptable): No telescoping or delamination below 1500m, telescoping or delamination above 1500m E (Poor): Telescoping or delamination occurs at less than 1500m

[0132] (Laminate strength evaluation) The packaging materials obtained in the above Examples and Comparative Examples were cut into pieces 150 mm long and 15 mm wide, opened at the ink / OPP film and ink / PET film interfaces, and the laminate strength in the 90° direction was measured using a tensile tester. The evaluation results are shown in Table 6. (Evaluation Criteria) A (excellent): 1.5N / 15mm or more B (Good): 1.0N / 15mm or more, less than 1.5N / 15mm C (Acceptable): 0.8N / 15mm or more, less than 1.0N / 15mm D (unacceptable): 0.5N / 15mm or more, less than 0.8N / 15mm E (poor): less than 0.5N / 15mm

[0133] (Recyclability evaluation) The packaging material obtained in the above Examples and Comparative Examples was cut into a size of 4 cm x 4 cm, washed with water and dried. The pieces of packaging material were fed into a single-screw extruder, melted and kneaded at 220°C with a screw rotation speed of 250 rpm, and extruded from the discharge part of the extrusion device at a pressure of 4 MPa using a 150 mesh filter. Thereafter, the pieces were immediately cut with a pelletizer and cooled by immersing in cold water. In this way, pellets of recycled plastic recycled from the packaging material were obtained. Then, the recycled plastic pellets were extruded at 220°C using a T-die extruder to produce a film-shaped molded product with a thickness of 50 μm. The obtained film was cut into 0.5 m pieces. 2 The number of foreign objects and bubbles that could be visually identified per unit area was counted and evaluated according to the following criteria. The evaluation results are shown in Table 6. A (Excellent): The number of foreign objects or bubbles is less than 40. B (Good): The number of foreign objects or bubbles is between 40 and 80. C (Acceptable): The number of foreign objects or bubbles is between 80 and 120. D (Not acceptable): The number of foreign objects or bubbles is between 120 and 200. E (Poor): Number of foreign objects or bubbles is 200 or more

[0134] [Table 6]

Claims

1. A packaging material having a substrate, a printing layer, an adhesive layer, and a sealant in this order, The packaging material contains 80% by mass or more of a polyolefin resin, The arithmetic mean height Sa value of the surface of the printing layer as defined in ISO 25178 is 2.0 μm or less; The adhesive layer is a cured product of a solventless adhesive containing a polyol (A) and a polyisocyanate (B), the polyol (A) contains a structural unit derived from a polyether polyol and / or a structural unit derived from a polyester polyol, and the polyester polyol contains a polyester polyol obtained by ring-opening polymerization of a lactone or a polyester polyol obtained by reacting a polyvalent carboxylic acid with a polyhydric alcohol; The packaging material, wherein the blending amount of the polyol (A) is 30 to 100 mass % based on the polyisocyanate (B).

2. 2. The packaging material according to claim 1, wherein the reaction equivalent ratio [NCO / OH] of all isocyanate groups in the polyisocyanate (B) to all hydroxyl groups in the polyol (A) is 1.0 to 2.

0.

3. 3. The packaging material according to claim 1 or 2, wherein the solvent-free adhesive has a shear stress of 1.5 N or more under the following test conditions. (Test conditions) Using the solventless adhesive, an adhesive layer is formed on the corona-treated surface of a polyethylene terephthalate substrate 1 having a thickness of 25 μm and a wet tension of the corona-treated surface of 45 to 60 mN / m, with an application amount of 1.9 to 2.1 g / m2, and the adhesive layer is bonded to a corona-treated surface of a polyethylene terephthalate substrate 2 having a thickness of 25 μm and a wet tension of the corona-treated surface of 45 to 60 mN / m so that the bonding area is 25 mm x 25 mm to obtain a test specimen. The test specimen is kept at 20° C. and a humidity of 65% for 1 hour, and then a tensile test of the substrate 1 and substrate 2 of the test specimen is performed in an environment of 80° C. to measure the shear stress.

4. The packaging material according to claim 1 or 2, wherein the solventless adhesive has a viscosity at 40°C of 500 to 4000 mPa·s measured in accordance with JIS K5600-2-3 immediately after mixing the polyol (A) and the polyisocyanate (B) at 40°C.

5. 3. The packaging material according to claim 1 or 2, wherein the viscosity at 40°C measured in accordance with JIS K5600-2-3 after compounding the solventless adhesive at 40°C and then leaving it at 40°C for 20 minutes is 6000 mPa·s or less.

6. 3. The packaging material according to claim 1, wherein the printed layer comprises a pigment and a binder resin, and the binder resin has a chlorine content of 5 mass % or less.

7. The packaging material according to claim 6 , wherein the content of the pigment is 30% by mass or less based on the total mass of the printed layer.

8. 3. The packaging material according to claim 1, wherein the chlorine content is 0.4 mass% or less based on the total mass of the packaging material.

9. A method for producing a packaging material having a substrate, a printing layer, an adhesive layer, and a sealant in this order, and containing 80% by mass or more of a polyolefin resin, comprising: A step of forming a printing layer on a substrate, the printing layer having a surface with an arithmetic mean height Sa value defined in ISO 25178 of 2.0 μm or less; Contains a polyol (A) and a polyisocyanate (B), the polyol (A) contains a structural unit derived from a polyether polyol and / or a structural unit derived from a polyester polyol, and the polyester polyol contains a polyester polyol obtained by ring-opening polymerization of a lactone or a polyester polyol obtained by reacting a polyvalent carboxylic acid with a polyhydric alcohol; A method for producing a packaging material, comprising the step of applying a solventless adhesive in which the blending amount of the polyol (A) is 30 to 100 mass % relative to the polyisocyanate (B).

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