Packaging material and method for producing 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 manufacturing the same.

Background Art

[0002] From the viewpoints of environmental measures and effective use of resources, various studies have been conducted on the recycling of plastic products. In recent years, demands for material recycling have been particularly increasing towards the realization of a recycling-oriented society.

[0003] Among plastic products, packaging materials made of plastic films have a multilayer structure in order to meet different required performances for each application. On the other hand, since packaging materials having a plurality of types of materials are difficult to separate or classify into single materials and material cycling is difficult, in recent years, for example, the conversion of packaging materials into single materials as in Patent Document 1 has been studied.

[0004] In the case of laminate adhesives used for packaging materials, mainly solvent-based and solventless laminate methods can be mentioned. However, due to the strengthening of regulations and considerations for environmental protection or safety, the demand for switching to solventless types is increasing. Recently, not only the two-layer structure, which has been the main configuration of solventless laminates, but also the use of solventless adhesives for laminate configurations of three layers or more, which have conventionally been performed with solvent-based adhesives, has been studied. However, solventless adhesives are designed with a low molecular weight of the resin contained from the viewpoints of handleability, cleanability, or appearance performance and pot life, and tend to have a slower rise in cohesive force after lamination compared to solvent-based laminates.

[0005] Therefore, when applying a solvent-free adhesive, appearance defects are likely to occur due to bubbles entrapped during the application or carbon dioxide gas generated by the reaction of the polyisocyanate compound, which is a component of the adhesive, with moisture in the air. In addition, other problems such as delamination caused by bubbles or carbon dioxide gas, and telescoping (the roll becoming bamboo shoot-shaped during winding) caused by the laminated film slipping and shifting in the shear direction also occur. When a printing layer is present, these defects are more likely to occur due to the penetration of the adhesive into the printing layer and the unevenness on the surface of the printing layer.

[0006] For example, Patent Document 2 describes that by using a solvent-free adhesive with high tensile shear strength, the adhesive strength and processing appearance are improved, but there is no description regarding a method for improving the lamination appearance in a substrate having a printing layer.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a packaging material that is excellent in lamination strength and lamination appearance and suitable for material recycling.

Means for Solving the Problems

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

[0010] That is, the present invention is 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 defined in ISO 25178 on the surface of the printing layer is 2.0 μm or less, The present invention relates to a packaging material in which 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 shear stress of the solventless adhesive under the following test conditions is 1.5 N or more. (Test conditions) Using the solventless adhesive, a coating amount of 1.9 to 2.1 g / m is applied on 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 it is bonded to the corona-treated surface of a substrate 2 having the same thickness and wetting tension as the substrate 1 so that the bonding area is 25 mm × 25 mm to obtain a test piece. After holding the test piece at 20°C and 65% humidity for 1 hour, a tensile test of the substrate 1 and the substrate 2 of the test piece is performed in an 80°C environment, and the shear stress is measured.

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

[0013] The present invention also relates to the above packaging material, wherein the viscosity of the solventless adhesive at 40°C measured according to JIS K5600-2-3 after blending the solventless adhesive at 40°C and then standing still 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-described packaging material, wherein the printing layer contains a pigment and a binder resin, and the chlorine content of the binder resin is 5% by mass or less.

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

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

[0018] The present invention also relates to a method for manufacturing a packaging material having a base material, a printing layer, an adhesive layer, and a sealant in this order, and containing 80% by mass or more of a polyolefin resin, a step of forming a printing layer having a surface with an arithmetic mean height Sa value of 2.0 μm or less as defined in ISO 25178 on the base material, a method for manufacturing a packaging material, including a step of applying a solvent-free adhesive containing a polyol (A) and a polyisocyanate (B).

Advantages of the Invention

[0019] According to the present invention, it has become possible to provide a packaging material that is excellent in laminate strength and laminate appearance and is suitable for material recycling.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements 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 exceed the gist thereof.

[0021] Hereinafter, the packaging material of the present invention will be described in detail. The present invention is a packaging material having a base material, 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 defined in ISO 25178 of the surface of the printing layer is 2.0 μm or less, The present invention relates to a packaging material in which the adhesive layer is a cured product of a solvent-free adhesive containing a polyol (A) and a polyisocyanate (B). By including 80% by mass or more of a polyolefin resin in the total mass of the packaging material, a molding material with high recyclability, good moldability, and usability for various applications can be obtained. Moreover, it is preferable that the surface of the printing layer and the adhesive layer are adjacent to each other. By forming an adhesive layer, which is a cured product of a solvent-free adhesive containing a polyol (A) and a polyisocyanate (B), on the surface of the printing layer with an arithmetic mean height Sa value of 2.0 μm or less defined in ISO 25178, the generation of bubbles can be suppressed, the leveling property and the adhesion between layers can be 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. The structure can be specifically exemplified by the following structures, but is not limited thereto. In the structure representations of the following (1) to (3), " / " means the boundary of each layer. Specifically, the laminate structure can be exemplified by the following laminate structures in order from the outer layer side (left side). (1) Base material / Printing layer / Adhesive layer / Sealant (2) Base material / Printing layer / Adhesive layer / Intermediate base material / Adhesive layer / Sealant (3) Base material / Printing layer / Adhesive layer / First intermediate base material / Adhesive layer / Second intermediate base material / Adhesive layer / Sealant

[0023] The packaging material contains 80% by mass or more of a polyolefin resin in the total mass of the packaging material. The content is more preferably 85% or more, and still more preferably 90% by mass or more. By including the polyolefin resin in the above range, the packaging material has high simplicity in the separation process and recyclability, good moldability, and a molding material that can be used for various applications can be obtained. Also, from the perspective of recyclability, it is preferable that the base material, the sealant, and the intermediate base material used as required are made of the same material (monomaterial). Further, it is preferable that the base material, the sealant, and the intermediate base material used as required contain a polyolefin resin. Furthermore, in the total mass of the base material, the sealant, and the intermediate base material used as required, it is preferable that the polyolefin resin accounts for 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Moreover, it is more preferable that the polyolefin resin is a polypropylene-based resin and / or a polyethylene-based resin, still more preferably the polyolefin resin is a polypropylene-based resin, and particularly preferably the polypropylene-based resin is a copolymer with ethylene and / or butene.

[0024] <Chlorine content of the packaging material> Due to the halogen elements that may be contained in the packaging material, hydrogen chloride, which is a halogen gas or an acidic gas, may be generated during pellet production, which may damage the equipment or pose a threat to human health. Moreover, when bubbles are generated during pellet production, when a molded product is produced using the produced pellets, unevenness is likely to occur on the surface, and the surface state of the molded product may deteriorate. Therefore, in the packaging material, it is preferable that the chlorine content is 0.4% by mass or less, more preferably 0.2% by mass or less, still more preferably 0.1% by mass or less, and particularly preferably 0.05% by mass or less in the total mass of the packaging material. The chlorine content of the packaging material can be specified by the same method as the analysis method of the chlorine content described later.

[0025] <Printing layer> The printing layer can be a layer that displays any pattern, design, characters, symbols, etc. for the purpose of decoration or imparting aesthetic sense; indication of contents, expiration date, manufacturer or seller, etc. The printing layer may be a solid printing layer without patterns, designs, characters, symbols, etc. The method for forming the printing layer is not particularly limited, and as described later, it is preferably formed using printing ink containing a pigment and a binder resin. Also, the printing layer may have a single-layer structure or a multi-layer structure. The thickness of the printing 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) Also, by having the arithmetic mean height Sa value defined in ISO 25178 on the surface of the printing layer within the range of 2.0 μm or less, a packaging material having excellent laminating strength and laminating appearance can be obtained. In the present invention, the surface of the printing layer refers to the surface on the side opposite to the substrate on which printing is performed in the printing layer. The arithmetic mean height Sa value on the surface of the printing layer can be within the above range by appropriately setting the solvent composition in the ink, pigment ratio, selection of additives such as leveling agents, ink viscosity during printing, printing speed, drying temperature, and pressure conditions of the impression cylinder of the printing machine. If the above arithmetic mean height Sa value is 2.0 μm or less, air bubbles are less likely to be mixed in, and the occurrence of appearance defects and delamination is suppressed. Also, it is more preferable that the arithmetic mean height Sa value is 0.1 μm or more. In that case, the anchor effect of the adhesive is exhibited on the printing layer, and the adhesive strength between the printing layer and the adhesive layer is improved. The arithmetic mean height Sa value is more preferably 0.3 to 1.5 μm, and still more preferably 0.5 to 1.0 μm.

[0027] The arithmetic mean height Sa value on the surface of the printing layer is measured using a white light interference type surface property measuring machine (Talysurf CCI MP-HS manufactured by AMETEK). The measurement and analysis method is performed in accordance with ISO 25178.

[0028] (Chlorine content of the printing layer) It is preferable that the chlorine content rate of the printing layer is 8% by mass or less in the total mass of the printing layer, because it is excellent in environmental safety and it is difficult for free chlorine to be generated. The chlorine content rate is more preferably 5% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2% by mass or less. Also, forms of 1% by mass or less or 0.5% by mass or less are particularly preferable. The chlorine content rate of the printing layer can be specified by the same method as the analysis method of the chlorine content described later.

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

[0030] (Organic pigment) Examples of the organic pigment include, but are not limited to, the following: soluble azo-based, insoluble azo-based, azo-based, phthalocyanine-based, halogenated phthalocyanine-based, anthraquinone-based, ansanthrone-based, dianthraquinonyl-based, anthrapyrimidine-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, flavanthrone-based, diketopyrrolopyrrole-based, isoindoline-based, indanthrone-based, carbon black-based pigments, etc.

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

[0032] (Inorganic Pigment) Examples of the inorganic pigment include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, aluminum particles, mica, bronze powder, chrome vermilion, lead yellow, cadmium yellow, cadmium red, ultramarine, cobalt blue, red iron oxide, iron black, titanium oxide, zinc oxide, etc. Aluminum has a leafing type or a non-leafing type, and the non-leafing type is preferable.

[0033] (Binder resin) The printing layer is preferably formed using printing ink containing a binder resin. The binder resin refers to the binder resin in the printing layer, and as will be described later, it is preferably such that the chlorine content is 5% by mass or less in the total binder resin. It is still more preferably 3% by mass or less or 1% by mass or less.

[0034] Examples of the binder resin include, but are not limited to, urethane resin, cellulose-based resin, polyamide resin, rosin-based resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinyl acetate resin, acrylic resin, styrene resin, damar resin, styrene-maleic acid copolymer resin, polyester resin, alkyd resin, terpene resin, phenol-modified terpene resin, ketone resin, cyclized rubber, polyvinyl acetal resin, petroleum resin, and modified resins thereof. These resins can be used alone or in combination of two or more. Among them, it is preferably substantially free of vinyl chloride-vinyl acetate copolymer resin, and more preferably contains urethane resin.

[0035] Also, the above binder resin is preferably a thermoplastic resin soluble in an organic solvent. It is preferable to use in combination a resin having a glass transition temperature of -60°C or higher and lower than 40°C and a resin having a glass transition temperature of 40°C or higher and 200°C or lower. More preferably, it is to use in combination a resin having a glass transition temperature of -50°C or higher and 0°C or lower and a resin having a glass transition temperature of 50°C or higher and 190°C or lower. In this specification, the glass transition temperature is a measured value in a differential scanning calorimeter (DSC). Examples of the resin having a glass transition temperature of -60°C or higher and lower than 40°C mainly include urethane resin. Examples of the resin having a glass transition temperature of 40°C or higher and 200°C include polyvinyl acetal resin, cellulose ester resin, rosin resin, etc., and polyvinyl acetal resin is preferable.

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

[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. Preferred are urethane resins composed of polyol and polyisocyanate, urethane prepolymers of terminal isocyanate composed of polyol and polyisocyanate, and urethane resins obtained by reacting with polyamine. Examples of the production method include the method described in JP-A-2013-256551.

[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 still more preferably a resin having an acetal ring structure. These ring structures may have a double bond or an alkyl group or other substituents.

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

[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, the constituent unit derived from α-methylstyrene is 50% by mass and the constituent unit derived from butyl methacrylate as an acrylic monomer is 50% by mass, the content of the ring structure is 50% by mass.

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

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

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

[0044] (Cellulose ester resin) As the cellulose ester resin, a cellulose acetate alkynate resin is preferable, and for example, cellulose acetate propionate and cellulose acetate butyrate are preferably 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, and a hexyl group are preferably used. The alkyl group may have a substituent. The weight average molecular weight of the cellulose ester resin is preferably from 5,000 to 200,000, more preferably from 10,000 to 100,000, and still more preferably from 15,000 to 80,000. The glass transition point of the cellulose ester resin is preferably from 120 °C to 180 °C, more preferably from 130 to 170 °C. By using the urethane resin and the cellulose ester resin in combination, printability, blocking resistance, etc. are improved.

[0045] (Rosin resin) The rosin resin refers to a resin having as a main component a structural unit derived from rosin acid (for example, abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, dehydroabietic acid). 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 phenol 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 even more preferably 150 mgKOH / g or less. In one embodiment, the acid value is preferably 100 mgKOH / g or less, and more preferably 50 mgKOH / g or less. The softening point of the rosin resin is preferably 60 to 180 °C, more preferably 70 to 150 °C. In this specification, the softening point is a measured value by the ring and ball method and can be measured in accordance with JIS K2207.

[0046] (Rosin ester) As the rosin resin, 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 rosin acid is preferable. The low molecular weight polyol preferably has 2 to 4 hydroxyl groups in one molecule (hereinafter may be abbreviated as 2 to 4 functional) and a molecular weight of 50 to 500. Examples of such low molecular weight polyols include bifunctional low molecular weight polyols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,10-decanediol; trifunctional low molecular weight polyols such as glycerin and trimethylolpropane; and tetrafunctional low molecular weight polyols such as erythritol and pentaerythritol. Among them, trifunctional and / or tetrafunctional low molecular weight polyols are preferable. The weight average molecular weight of the rosin ester is preferably 500 to 2,000, more preferably 500 to 1,500.

[0047] (Acrylic resin) The acrylic resin has a high affinity with the plastic substrate, and by using it as a binder resin, an ink with high adhesion to the substrate can be obtained. In this specification, "acrylic resin" means a polymer having acrylic monomers as constituent units. Also, "acrylic monomer" means a monomer having an acrylic group or a methacryloyl group, and "methacrylic and acrylic" may be collectively referred to as "(meth)acrylic" for short. Also, "methacrylate and acrylate" may be collectively referred to as "(meth)acrylate" for short. The 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, as alkyl (meth)acrylates, 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, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, and as aromatic ring-containing acrylic monomers, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, etc. can be mentioned. 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 °C to 80 °C. The weight average molecular weight (Mw) of the acrylic resin is preferably 20,000 to 300,000.

[0048] [Chlorine content of the binder resin] The chlorine content of the binder resin is preferably 5% by mass or less, including the case where it is 0. More preferably, the chlorine content is 4% by mass or less, still more preferably 3% by mass or less, and particularly preferably 2% by mass or less. Also, forms where it is 1% by mass or less or 0.5% by mass or less are particularly preferred. The above chlorine content is the content rate (% by mass) of chlorine atoms based on the mass of the binder resin. When the chlorine content is 5% by mass or less, environmental safety is excellent and it becomes difficult for free chlorine to be generated.

[0049] The above chlorine content can be measured using known methods such as ion chromatography (IC) and ICP mass spectrometers (ICP-MS). Examples of measuring instruments include LC-20ADsp manufactured by Shimadzu Corporation for IC and Agilent 7700x manufactured by Agilent Technologies for ICP-MS. Also, the chlorine content of the printing layer can be simply calculated from the chlorine content of each raw material constituting the printing layer by the following formula. The same applies to other layers and the entire packaging material. Formula: Chlorine content rate (%) in the total solid mass of the binder resin = Mass of chlorine in the total solid mass of the binder resin / Total solid mass of the binder resin (%) Formula: Chlorine content rate (%) in the total solid mass of the printing layer = Mass of chlorine in the total solid mass of the printing layer / Total solid mass of the printing 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 nitration of the binder resin) The binder resin preferably has a nitration degree of 1% by mass or less, including the case where it is 0. When the nitration degree is 1% by mass or less, NO X gas generation can be suppressed, and a more safe recycling material can be provided. The nitration degree refers to the degree of esterification of nitrate ester expressed by the nitrogen content (mass %), for example, commercially available nitrocellulose is usually 10 to 12 mass %. The nitration degree of the binder resin is more preferably 0.6 mass % or less, still more preferably 0.4 mass % or less, and particularly preferably 0.2 mass % or less. When the binder resin contains a urethane resin, the nitration degree of the urethane resin is preferably 0.3 mass % or less, still more preferably 0.2 mass % or less, and even more preferably 0.1 mass % or less.

[0052] <Adhesive layer> The adhesive layer in the present invention is a cured product of a solventless adhesive. Hereinafter, the solventless adhesive may be simply referred to as "adhesive", which is synonymous. 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 still more preferably 2.5 N or more. Also, it is preferably 10.0 N or less, more preferably 7.5 N or less, and still more preferably 5.0 N or less. (Test conditions) On the corona-treated surface of a polyethylene terephthalate substrate 1 with a thickness of 25 μm and a wetting tension of 45 to 60 mN / m on the corona-treated surface, an adhesive layer with a coating amount of 1.9 to 2.1 g / m 2 is formed, and it is bonded to the corona-treated surface of a substrate 2 having the same thickness and wetting tension as the substrate 1 so that the bonding area is 25 mm × 25 mm to form a test piece. After holding the test piece at 20°C and 65% humidity for 1 hour, a tensile test of the substrate 1 and the substrate 2 of the test piece is performed in an 80°C environment, and the shear stress is measured. In the present invention, the measurement of the shear stress is performed 5 times, and the average value is used. As the shear stress measuring device, a general tensile tester can be used.

[0053] More specifically, the shear stress is the stress generated in a shear deformation in which a film arranged so as to sandwich an adhesive resin is slid in a plane-parallel direction, and is generated in the film traveling direction (plane-parallel direction) in the laminating process. More specifically, when any of the impression roll, coating roll, nip roll, and touch roll included in the laminating apparatus passes through the laminated packaging material, the above shear force causes displacement between the films, resulting in defects such as bubbles and delamination. When there are many voids such as delamination parts and bubble parts in the packaging material, the packaging material tends to contain moisture in the washing process of the packaging material for material recycling. When the moisture content in the packaging material becomes high, it causes foaming when producing recycled pellets, and there is a risk of unevenness occurring on the surface of the subsequent molded product. When the above shear stress is 1.5 N or more, the slippage and displacement between the base materials used for lamination are suppressed, and the form immediately after lamination can be maintained. When laminating using the above solvent-free adhesive, the mixing of bubbles and the occurrence of telescoping and the like can be suppressed.

[0054] Hereinafter, the components constituting the solvent-free adhesive of the present invention will be described in detail.

[0055] (Polyol (A)) The polyol (A) constituting the solvent-free adhesive may be a compound having two or more hydroxyl groups, and can be selected from known polyols. Examples of the polyol include polyester polyol, polycarbonate polyol, polycaprolactone polyol, polyether polyol, polyolefin polyol, acrylic polyol, silicone polyol, castor oil-based polyol, and fluorine-based polyol. These polyols may be used alone or in combination of two or more. The polyol (A) preferably contains polyether polyol and / or polyester polyol, and more preferably contains polyether polyol, from the viewpoints of leveling property to the base material, adhesive performance, and viscosity described later.

[0056] (Polyether polyol) The polyether polyol may be a compound having two or more hydroxyl groups and 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 the bifunctional polyether polyol 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 adduct, glycerin propylene oxide adduct, sorbitol-based propylene oxide adduct, and sucrose-based propylene oxide adduct.

[0057] Examples of polyether polyols having three or more functional groups include aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol; modified polyether polyols obtained by ring-opening polymerization of such aliphatic polyols with various compounds containing cyclic ether bonds 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 such 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 and a hydroxy group component; and polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone). Preferably, the carboxy group component is a polyvalent carboxylic acid having primary hydroxy groups at both ends, such as acyclic aliphatic dicarboxylic acids like succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, and fumaric acid; alicyclic dicarboxylic acids like 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids like terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthoic 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; polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids, and dimer acid. Among them, from the viewpoint of reactivity, the carboxy group component preferably contains an acyclic aliphatic dicarboxylic acid, more preferably contains 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, 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 diol and various cyclic ether bond-containing compounds such as ethylene oxide and tetrahydrofuran; lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic diol and various lactones such as lactanoid and ε-caprolactone; 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 polyol having three or more functional groups include aliphatic polyols such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol, and pentaerythritol; modified polyether polyols obtained by ring-opening polymerization of the aliphatic polyol and 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; lactone-based polyester polyols obtained by polycondensation reaction of the aliphatic polyol and various lactones such as ε-caprolactone. Among them, from the perspective of reactivity, the polyhydric alcohol preferably contains an aliphatic diol, and more preferably contains diethylene glycol.

[0061] As the carboxy group component and the hydroxyl group component constituting these polyester polyols, each may be used alone or in combination of two or more.

[0062] Hereinafter, preferred embodiments of the polyol (A) will be further described.

[0063] The polyol (A) may be an acid-modified product in which a part of the hydroxyl groups in the polyol is acid-modified, or may be a product in which an acid anhydride is reacted with a part of the hydroxyl groups in the polyol to introduce a carboxy group. Examples of the acid anhydride include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic acid ester anhydride. Examples of the trimellitic acid ester anhydride include ester compounds obtained by subjecting an alkylene glycol or an alkanetriol having 2 to 30 carbon atoms to an esterification reaction with trimellitic anhydride. Specifically, ethylene glycol bisanhydrotrimellitate, propylene glycol bisanhydrotrimellitate, etc. may be mentioned.

[0064] Further, 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 above polyether polyol or polyester polyol is modified with the above 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 mole number / OH mole number) 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 can be obtained, which is preferable because the adhesive strength of the adhesive is improved. When the molar equivalent ratio is 0.40 or less, the pot life of the adhesive is improved, which is preferable.

[0066] As the polyol (A) in the present invention, more preferably, it is a polyether-based urethane polyol obtained by modifying a polyether polyol with a polyisocyanate. When using a polyether-based urethane polyol, the flexibility and crosslink density in the adhesive are appropriately included, the adhesive strength is improved, and good coating suitability is provided, which is preferable.

[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 of the resin is improved, which is preferable. In addition, the number average molecular weight and weight average molecular weight in this specification are values converted to standard polystyrene using GPC (gel permeation chromatography) manufactured by Showa Denko KK and using tetrahydrofuran as a solvent.

[0068] The hydroxyl value of the polyol (A) is preferably 100 to 200, more preferably 120 to 180. When the hydroxyl value is 100 or more, a good crosslink density is provided and the adhesive strength is improved, which is preferable. When the hydroxyl value is 200 or less, the coating suitability is improved, which is preferable.

[0069] When synthesizing the above polyether-based urethane polyol, it is preferable to use a trifunctional polyol raw material. In that case, the content of the trifunctional polyol raw material contained in the total amount of the polyol raw materials is preferably 4.0% by mass or more and 12.0% by mass or less, more preferably 5.0% by mass or more and 10.0% by mass or less, and still more preferably 5.0% by mass or more and 8.5% by mass or less. When it is 4.0% by mass or more, crosslinking is efficiently formed, the shear stress is improved, and air bubble entrainment and telescoping can be suppressed, which is preferable. When it is 12.0% by mass or less, the flexibility is improved and the adhesive strength is improved, which is preferable.

[0070] (Polyisocyanate (B)) The polyisocyanate (B) constituting the solvent-free adhesive is not particularly limited, but is preferably one having a urethane bond, and more preferably a polyester urethane-based polyisocyanate and / or a polyether urethane-based polyisocyanate which is a reaction product of a polyester polyol and / or a polyether polyol and a polyisocyanate. More preferably, it contains a polyether urethane-based polyisocyanate. By containing a polyether urethane-based polyisocyanate, it is possible to achieve both flexibility and crosslink density in the adhesive, improve the shear stress and the adhesive strength, and further make the viscosity described later suitable.

[0071] (Polyester polyol) The above polyester polyol may be a compound having two or more hydroxyl groups and ester bonds in the molecule, and those described in the (polyester polyol) section of the above (polyol (A)) can be preferably applied.

[0072] (Polyether polyol) As the polyether polyol, any compound having two or more hydroxyl groups and ether bonds in the molecule may be used, and those described in the section of (polyether polyol) in the aforementioned (polyol (A)) can be preferably applied. Using a polyether polyol is preferable because the coating film of the adhesive becomes flexible and the adhesive strength is improved. Among them, from the viewpoints of coating film flexibility and resin compatibility, the polyether polyol is preferably a polyether polyol having a molecular weight of 400 to 2,000. When the molecular weight is 400 or more, it is preferable because the flexibility of the polymer chain in the adhesive increases. When the molecular weight is 2,000 or less, it is preferable because the compatibility with the isocyanate component is improved and the urethanization reaction easily proceeds.

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

[0074] Examples of the isocyanate compound used for 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 aromatic isocyanates 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 alicyclic aromatic isocyanates include alicyclic aromatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof. Examples of aliphatic isocyanates 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 methyl caproate, lysine diisocyanate, and dimer acid diisocyanate. Examples of cycloaliphatic isocyanates include cycloaliphatic 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(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, and norbornene diisocyanate.

[0076] Examples of modified isocyanate compounds include, for example, allophanate-type modified products, isocyanurate-type modified products, biuret-type modified products, adduct-type modified products, and reaction products having an isocyanate group and a urethane bond obtained by reacting the above isocyanate compound with a polyol 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. For example, polyester polyol, polyester urethane polyol, polycarbonate polyol, polycaprolactone polyol, polyether polyol, polyether urethane polyol, polyolefin polyol, acrylic polyol, silicone polyol, castor oil-based polyol, and fluorine-based polyol can be mentioned.

[0077] From the viewpoint of improving the shear stress and substrate adhesion of the adhesive, these isocyanate compounds are preferably aromatic isocyanates. More preferably, they contain diphenylmethane diisocyanate. 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-based polyisocyanate, which is a reaction product of a polyester polyol and / or a polyether polyol and 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 within the above range, it is preferable because it forms an appropriate crosslinking density and improves the adhesive strength.

[0079] In the solventless adhesive, from the viewpoint of making the viscosity described later suitable, etc., the reaction equivalent ratio [NCO / OH] of all the isocyanate groups of the polyisocyanate (B) and all the hydroxyl groups of the polyol (A) is preferably in the range of 1.0 to 2.0, more preferably in the range of 1.0 to 1.5. Further, the blending amount of the polyol (A) is preferably 30 to 100% by mass, more preferably 40 to 70% by mass, based on all the polyisocyanates, from the viewpoint of adhesion 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 blending the polyol (A) and the polyisocyanate (B) (for example, within 1 minute after blending). When the above viscosity is 100 mPa·s or more, it is preferable because the initial cohesion of the adhesive is excellent. When the above viscosity is 10,000 mPa·s or less, it is preferable because the coating applicability is excellent. Furthermore, the viscosity at 40°C measured in accordance with JIS K5600-2-3 immediately after blending the polyol (A) and the polyisocyanate (B) at 40°C is preferably 500 to 4,000 mPa·s, more preferably 1,000 to 3,000 mPa·s.

[0081] Also, in one embodiment, the solventless adhesive preferably has a viscosity at 40°C of 6,000 mPa·s or less, more preferably 5,000 mPa·s or less, measured in accordance with JIS K5600-2-3 after blending the polyol (A) and the polyisocyanate (B) at 40°C and then standing at 40°C for 20 minutes. More preferably, it is 4,000 mPa·s or less, and particularly preferably 3,500 mPa·s or less. When the viscosity (ICI viscosity) measured in accordance with JIS K5600-2-3 at 40°C is 6,000 mPa·s or less, it is preferable because the adhesive can be used for a long time without excessive thickening and the coating applicability is improved.

[0082] (Other components) The solventless adhesive may contain other components other than the above in order to meet various physical properties required for the adhesive or the package. 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, defoaming agents, silane coupling agents, phosphoric acid or phosphoric acid derivatives, silica, alumina, mica, talc, aluminum flakes, glass flakes and other inorganic fillers, layered inorganic compounds, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.), rust preventives, 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 can 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, vinyltriethoxysilane; trialkoxysilanes having an amino group such as 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane; trialkoxysilanes having a glycidyl group such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane. The content of the silane coupling agent is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass, based on the mass of the polyol (A). By setting the content of the silane coupling agent within the above range, the adhesive strength to metal-based materials such as inorganic vapor deposition layers and metal foils can be improved.

[0084] (Phosphoric acid or a phosphoric acid derivative) The solventless adhesive can contain phosphoric acid or a phosphoric acid derivative from the viewpoint of improving the adhesive strength to metal-based materials such as an inorganic vapor deposition layer and a metal foil. The phosphoric acid may be any one having at least one free oxyacid, and examples thereof include phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and metaphosphoric acid; condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Further, examples of the derivative of phosphoric acid include those obtained by partially esterifying the above-mentioned phosphoric acid with alcohols while leaving at least one free oxyacid. 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 its derivative is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, and particularly preferably 0.05 to 1% by mass based on the mass of the polyol (A).

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

[0086] As the base material containing a polyolefin resin, base materials made of only polyolefin resins may be simply laminated together, or a base material different from the base material made of a polyolefin resin may be laminated via adhesion or the like. Examples of the "base material different from the base material made of a polyolefin resin" include films having properties different from those of the base material made of a polyolefin resin, regardless of the type. Further, in the case of a laminated base material, it may be in a form including an adhesive layer. The method for laminating the above base materials is not particularly limited, and examples include conventionally known methods such as coextrusion molding, heat fusion, and pressure bonding via an adhesive layer.

[0087] Compared with an ester-based base material, the base material made of the above polyolefin resin has high resistance to an alkaline aqueous solution and heat during the molding process, and is less likely to undergo thermal decomposition, hydrolysis, etc. Therefore, the molecular weight can be maintained high during recycling. Further, from the viewpoint of ease of recovery after recycling, examples of the polyolefin base material include polyethylene such as biaxially stretched polypropylene (OPP), unstretched 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, copolymerized polypropylene, and films laminated therefrom. The thickness of the base material is not particularly limited, and considering the processability into a packaging container, it is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 70 μm or less. Among them, films having heat sealability are preferably used, and CPP, heat-sealable OPP, etc. correspond thereto.

[0088] The base material is preferably in a form such as a gas barrier base material, for example, a plastic base material having an inorganic vapor deposition layer such as aluminum, silica, or alumina; a plastic base material having an organic layer such as ethylene-vinyl alcohol copolymer or polyvinyl alcohol.

[0089] The base material preferably has a form (coating or kneading) containing additives such as an antistatic agent, an antifogging agent, and an ultraviolet inhibitor, a form having an easily adhesive coating layer (for example, a layer containing polyvinyl alcohol and its derivatives), a form in which the surface of the base material is subjected to corona treatment or low-temperature plasma treatment, and the like. The above-mentioned addition and processing are also carried out for the purpose of improving the wettability of printing ink and other coating agents, or for the purpose of imparting specific functionality to the film. For example, it is also preferably used suitably to provide a packaging material excellent in visibility of the contents by preventing fogging of the packaging material due to moisture.

[0090] <Intermediate base material> The packaging material of the present invention may further have an intermediate base material, and the intermediate base material preferably contains a polyolefin resin. Furthermore, in the total mass of the intermediate base material, it is preferable that the polyolefin resin is 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. Also, it is more preferable that the polyolefin resin is a polypropylene-based resin and / or a polyethylene-based resin, still more preferably the polyolefin resin is a polypropylene-based resin, and particularly preferably the polypropylene-based resin is a copolymer with ethylene and / or butene. Examples of the intermediate base material include polyolefin-based 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. A form that is a gas barrier base material, for example, a plastic base material having an inorganic vapor deposition layer such as aluminum, silica, or alumina, or a plastic base material having a layer in which organic and inorganic components are mixed is preferable.

[0091] <Sealant> The sealant has a role of protecting the object to be packaged by having the inner layer side surface in direct contact with the object to be packaged. In order to make the laminate bag-shaped, it is preferable that the innermost layer of the sealant has heat sealability. The sealant preferably contains a polyolefin resin. Furthermore, in the total mass of the sealant, the polyolefin resin is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more. Moreover, it is more preferable that the polyolefin resin is a polypropylene-based resin and / or a polyethylene-based resin, still more preferable that the polyolefin resin is a polypropylene-based resin, and particularly preferable that the polypropylene-based resin is a copolymer with ethylene and / or butene. Examples of the material constituting the sealant include polyolefin-based resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), ethylene-vinyl acetate copolymer, polypropylene homopolymer, and ethylene-propylene copolymer. One or more of these resins can be used. The sealant may be composed of a single layer or multiple layers of two or more layers. In addition, in order to suppress shrinkage during heat sealing, the sealant is preferably an unstretched film made of the above-mentioned resin.

[0092] The thickness of the sealant is not particularly limited and is appropriately set according to the use of the laminate and the type and properties of the packaged product. Usually, it is preferably 10 to 200 μm. In the case of a pouch (especially a retort pouch), the thickness of the sealant is preferably 20 to 150 μm, and more preferably 25 to 130 μm.

[0093] The sealant may be, for example, a sealant having an inorganic vapor deposition layer such as aluminum, silica, and alumina, or an organic layer such as ethylene-vinyl alcohol copolymer and polyvinyl alcohol. It may also be a milky white base material kneaded with a pigment or the like, or a composite base material by coextrusion.

[0094] (Method for manufacturing a packaging material) The manufacturing method of the packaging material of the present invention is a manufacturing method of a packaging material having a base material, a printing layer, an adhesive layer, and a sealant in this order, and containing 80% by mass or more of a polyolefin resin. The method includes a step of forming a printing layer having a surface with an arithmetic mean height Sa value of 2.0 μm or less as defined in ISO 25178 on the base material, and a step of applying a solvent-free adhesive containing polyol (A) and polyisocyanate (B). The adhesive layer may be applied on the printing layer and laminated, or may be applied on the sealant and laminated. As a preferred embodiment, for example, an embodiment in which the adhesive is applied and formed on the printing layer, and then the sealant is bonded. When the packaging material further has an intermediate base material layer, an embodiment including a step of once bonding the printing layer and the intermediate base material layer with an adhesive, and further bonding the intermediate base material layer and the sealant is preferable. The configuration is arbitrary and not particularly limited.

[0095] The packaging material thus obtained can be cut into a predetermined size and the edge portions can be heat-sealed in a form where the sealants are aligned with each other to form a bag shape. The heat-sealing temperature is preferably 50 to 250 °C, more preferably 80 to 180 °C. The heat-sealing pressure may be 1 to 5 kg / cm 2 and other conditions. One packaging material may be bent and the edge may be heat-sealed, or two or more packaging materials may be heat-sealed. Further, the bag made of the packaging material may be one in which all the openings are heat-sealed after packaging the contents.

Examples

[0096] Hereinafter, the present invention will be described in detail 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 mass % unless otherwise noted.

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

[0099] (Amine value) The amine value is the same as the number of milligrams of potassium hydroxide equivalent to the amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of the sample, and was measured in accordance with JIS K0070. That is, the sample was accurately weighed at 0.5 - 2 g (sample solid content: S g). 50 mL of a mixed solution of methanol / methyl ethyl ketone = 60 / 40 (mass ratio) was added to the accurately weighed sample and dissolved. Bromophenol blue was added as an indicator to the resulting solution, and the resulting solution was titrated with a 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 taken as the end point, and using the titration volume (A mL) at this time, the amine value was determined by the following formula. (Formula) Amine value = (A × f × 0.2 × 56.108) / S [mg KOH / g] (Weight average molecular weight, number average molecular weight)

[0100] (Weight average molecular weight, number average molecular weight) The weight average molecular weight and number average molecular weight were determined as the converted molecular weights using polystyrene as a standard substance by measuring the molecular weight distribution using a gel permeation chromatography (GPC) apparatus (HLC - 8220 manufactured by Tosoh Corporation). The measurement conditions are shown below. Column: The following columns were connected in series and used. TSKgel SuperAW2500 manufactured by Tosoh Corporation TSKgel SuperAW3000 manufactured by Tosoh Corporation TSKgel SuperAW4000 manufactured by Tosoh Corporation TSKgel guard column SuperAWH manufactured by Tosoh Corporation Detector: RI (differential refractometer) Measurement conditions: Column temperature 40°C Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min

[0101] (Glass transition temperature (Tg)) The glass transition temperature was determined by differential scanning calorimetry (DSC). The measurement was carried out using a DSC8231 manufactured by Rigaku Corporation under the 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 defined as the glass transition temperature.

[0102] (Chlorine content) The chlorine content was measured in accordance with JIS K0127 (2013). That is, on a transparent substrate, the ink or binder resin was each applied 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 a combustion method, and the chlorine content of the obtained sample was quantified by ion chromatography to determine the chlorine content rate.

[0103] (Measurement method of NCO content rate) Approximately 1 g of the sample was weighed into a 200 mL Erlenmeyer flask, and 10 mL of a toluene solution of 0.5 N di-n-butylamine and 10 mL of toluene were added thereto to dissolve the sample. Next, phenolphthalein test solution was added as an indicator, and after holding for 30 seconds, it was titrated with a 0.25 N hydrochloric acid solution until the solution showed a light red color. The NCO content rate (mass %) was determined by the following (formula). (Formula): NCO (mass %) = {(b - a) × 4.202 × F × 0.25} / S S: Sampling amount of the sample (g) a: Consumption amount of 0.25 N hydrochloric acid solution (ml) b: Consumption amount of 0.25 N hydrochloric acid solution in the blank experiment (ml) F: Normality of 0.25 N hydrochloric acid solution

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

[0105] (Shearing stress) The shearing stress of the solvent-free adhesive was measured as follows. <1>Polyol (A) and polyisocyanate (B) were compounded and applied at a coating amount of 2.0 g / m 2 onto a polyethylene terephthalate film with a thickness of 25 μm and a wetting tension of 45 to 60 mN / m. After application, the same polyethylene terephthalate film was laminated with 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 bonded area of 25 mm × 25 mm was prepared, and the shearing stress was measured by a tensile test in an 80°C environment using the test piece. The tensile test was performed at a tensile speed of 30 cm / min. In addition, the above measurement was performed 5 times, and the average value was used.

[0106] (Arithmetic mean height Sa) The arithmetic mean height Sa value of the printed layer surface was measured using a white light interference type surface property measuring machine (for example, Talysurf CCIMP-HS manufactured by AMETEK). As a measurement sample, the film was cut into an arbitrary size of about 2 cm square, and in a state where wrinkles were fully stretched, it was set on the measurement stage using an electrostatic adhesion plate or the like. For measurement, a 5x objective lens was used to perform measurement per field of view (1024×1024 pixels / 3.17 mm×3.17 mm), and this operation was performed at 10 locations at 5 mm intervals in the flow direction from the central location in both the flow direction and the width direction of the surface of the printed layer of the target sample film. Next, for the obtained data, noise was removed by non-measurement point processing, followed by leveling processing by the least squares method and shape removal processing by a polynomial, and then the waviness component was removed by robust Gaussian filter (cutoff value 0.25 mm) processing. Thereby, the state of the surface of the printed layer is made into a state where it can be appropriately measured. Next, using the analysis software "Talymap", the Sa value (μm) was obtained by an analysis method conforming to ISO25178, and the average value of each value obtained at the above 10 locations was calculated.

[0107] <Synthesis of urethane resin> (Synthesis Example 1) Urethane resin PU1 100 parts of a polyester polyol (hereinafter referred to as "MPD / SA") having a number average molecular weight of 2,000, which is a condensate of 3-methyl-1,5-pentanediol (MPD) and sebacic acid (SA), 1 part 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 having terminal isocyanate. Next, 11.0 parts of isophoronediamine (hereinafter referred to as "IPDA"), 1.0 part of N-(2-aminoethyl)ethanolamine (hereinafter referred to as "AEA"), 1.0 part of dibutylamine (hereinafter referred to as "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 having terminal isocyanate was gradually added at 40 ° C. React at 80 °C for 1 hour to obtain a solution of urethane resin PU1 with a solid content of 30% by 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 is 0% by mass.

[0108] (Synthesis Example 2) Urethane resin PU2 30 parts of a polyester polyol with a number average molecular weight of 2,000, which is a condensate of neopentyl glycol (NPG) and adipic acid (AA), 70 parts of polypropylene glycol with a number average molecular weight of 1,000 (PPG1000), 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 under a nitrogen atmosphere to obtain a urethane prepolymer with 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. React at 80 °C for 1 hour to obtain a solution of urethane resin PU2 with a solid content of 30% by 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 is 0% by mass.

[0109] The compounding compositions and properties of urethane resins PU1 and 2 are shown in Table 1.

[0110]

Table 1

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

[0112] <Preparation of Ink> [Ink Preparation Example 1] Ink X1 40 parts of urethane resin PU1 solution, 15 parts of polyvinyl butyral resin (PVB) solution, 5 parts of C.I. Pigment Blue 15:3 (manufactured by Toyo Color Co., Ltd., product name: LIONOL BLUE FG-7330, chlorine content 0% by mass, nitration degree 0% by mass), 0.8 part of silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 / g), 33.4 parts of mixed solvent 2 (n-propyl acetate (NPAC) / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed in a bead mill for 20 minutes to obtain a pigment dispersion. To the obtained pigment dispersion, 0.8 part of chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0 °C), and 1.5 parts of water were stirred and mixed 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 C.I. Pigment Blue 15:3 (manufactured by Toyo Color Co., Ltd., product name: LIONOL BLUE FG-7330, chlorine content 0% by mass, nitration degree 0% by mass), 0.8 part of silica particles (hydrophilic silica, average particle diameter 3.0 μm, specific surface area 300 m 2 / g) 0.8 parts, 33.4 parts of mixed solvent 2 (n-propyl acetate / isopropanol = 70 / 30 (mass ratio)) were mixed and dispersed with a bead mill for 20 minutes to obtain a pigment dispersion. To the obtained pigment dispersion, 0.8 parts of a chlorinated polypropylene solution, 3.5 parts of propylene glycol monomethyl ether (boiling point 121.0 °C), and 1.5 parts of water were stirred and mixed to obtain organic solvent-based ink X2.

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

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

[0116] The composition and properties of the organic solvent-based inks X1 to X4 are shown in Table 2.

[0117]

Table 2

[0118] (Method for producing polyol (A)) (Synthesis of polyol (A) A1) Into a reaction vessel equipped with a stirrer, a temperature system, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 84.4 parts of a triol having a number average molecular weight of about 400 obtained by adding polypropylene glycol to glycerin, 6.9 parts of trimethylolpropane, 207.7 parts of polypropylene glycol having a number average molecular weight of about 2,000, 235.4 parts of polypropylene glycol having a number average molecular weight of about 400, 205.4 parts of polytetramethylene glycol having a number average molecular weight of about 2,000, and 60.2 parts of tolylene diisocyanate were charged, and the mixture was heated at 80°C to 90°C for 3 hours with stirring under a nitrogen gas stream to carry out a urethanization reaction, thereby obtaining a polyol (A) A1 having a urethane bond.

[0119] (Synthesis of polyol (A) A2) Into a reaction vessel equipped with a stirrer, a temperature system, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 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 were charged, and the temperature was raised to 260°C with stirring under a nitrogen stream. After continuing the reaction until the acid value became 5 or less, the pressure was gradually reduced, and the reaction was continued at 1 mmHg to remove the excess alcohol, thereby obtaining a polyol (A) A2 having a hydroxyl value of 60 mg KOH / g. The composition and properties of 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 compounding amounts as described in Table 4, a urethanization reaction was carried out in the same manner as 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) Into a reaction vessel equipped with a stirrer, a temperature system, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 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 with a number average molecular weight of about 400 obtained by adding polypropylene glycol to glycerin, 2.6 parts of trimethylolpropane, 31.8 parts of polypropylene glycol with a number average molecular weight of about 400, 289.4 parts of polypropylene glycol with a number average molecular weight of about 2,000, and 77.8 parts of polytetramethylene glycol with a number average molecular weight of about 1,000 were charged. While stirring under a nitrogen gas stream, it was heated at 80°C to 90°C for 3 hours to carry out a urethanization reaction, and polyisocyanate (B) B1 having a urethane bond with an isocyanate group content of 11.1% was obtained.

[0124] (Synthesis of polyisocyanate (B) B2 to B6) Except for changing the raw materials and compounding amounts as described in Table 5, a urethanization reaction was carried out in the same manner as 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: Biaxially oriented polypropylene film (thickness 20 μm) with one-sided surface corona discharge treatment PET: Corona discharge treatment on one-sided surface, biaxially oriented polyethylene terephthalate film (thickness 12 μm) CPP: Corona discharge treatment on one-sided surface, unoriented polypropylene film (thickness 30 μm)

[0127] [Example 1] (Production of packaging material C1) Using a propyl acetate / IPA mixed solvent (mass ratio 70 / 30), the viscosity of Ink X1 in a Zahn cup #3 (manufactured by Reika Co., Ltd.) was diluted and adjusted to 15 seconds (at 25°C), and a gravure printing machine equipped with a gravure plate with a plate depth of 35 μm was used to Printing print at a speed of 150 m / min on the corona-treated surface of an OPP film, and dried at 50°C to obtain a printed product (OPP) with an arithmetic mean height Sa value of 0.8 μm on the printed surface. After drying the printed layer, the coating amount was 2.5 g / m 2 as follows. Next, polyol (A) A1 and polyisocyanate (B) B1 were blended at 40°C to obtain a solvent-free adhesive. Using a laminator under normal temperature environment, the corona-treated surface of a 30-μm-thick CPP film, the printed surface obtained above, and the solvent-free adhesive were applied at a coating amount of 2.0 g / m 2 and laminated at a lamination speed of 200 m / min for 3000 m. After that, it was kept warm at 40°C for 2 days to completely cure the adhesive, and a packaging material C1 with a structure of OPP / printed layer / adhesive layer / CPP was obtained.

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

[0129] [Comparative Example 1] (Packaging material D1) Using a propyl acetate / IPA mixed solvent (mass ratio 70 / 30), the viscosity of Ink X2 in a Zahn cup #3 (manufactured by Reika Co., Ltd.) was diluted and adjusted to 18 seconds (at 25°C), and a gravure printing machine equipped with a gravure plate with a plate depth of 30 μm was used to PrintingPrinting was carried out on the corona-treated surface of the OPP film at a speed of 200 m / min, followed by drying at 50°C, to obtain a printed matter (OPP) with an arithmetic mean height Sa value of 2.2 μm on the printed surface. After drying the printing layer, the coating amount was 2.5 g / m 2 was set as such. Next, polyol (A) A1 and polyisocyanate (B) B1 were blended at 40°C at a mass ratio of (A) / (B) = 50 / 100 to obtain a solvent-free adhesive. Using a laminator under normal temperature environment, the corona-treated surface of a 30-μm thick CPP film, the printed surface obtained above, and the solvent-free adhesive were applied at a coating amount of 2.0 g / m 2 Then, after laminating at a speed of 200 m / min for 3000 m, it was kept warm at 40°C for 2 days to completely cure the adhesive, obtaining a packaging material D1 with a structure of OPP / printing layer / adhesive layer / CPP.

[0130] [Comparative Example 2] (Packaging Material D2) A packaging material D2 with a structure of PET / printing layer / adhesive layer / CPP was obtained in the same manner as in Example 1 except that the base material was changed to a PET film, according to the raw materials and blending amounts described in Table 6.

[0131] (Lamination Appearance Evaluation) In the winding rolls of the approximately 3000-m packaging materials obtained in the above Examples and Comparative Examples, visually observed from what distance from the winding start position telescoping and delamination occurred, and evaluated according to the following criteria. Note that telescoping means that the film slips in the shearing direction during winding, causing displacement and making the roll take the shape of a bamboo shoot. The evaluation results are shown in Table 6. A (Excellent): No telescoping and delamination B (Good): No telescoping and delamination within less than 2500 m, telescoping or delamination occurring at 2500 m or more C (Fair): No telescoping and delamination within less than 2000 m, telescoping or delamination occurring at 2000 m or more D (Poor): No telescoping and delamination within less than 1500 m, telescoping or delamination occurring at 1500 m or more E (Poor): Telescoping or delamination occurs at less than 1500 m

[0132] (Lamination Strength Evaluation) For the packaging materials obtained in the above Examples and Comparative Examples, cut them into pieces with a length of 150 mm and a width of 15 mm, open them at the ink / OPP film and ink / PET film interfaces, and measure the lamination strength in the 90° direction using a tensile tester. The evaluation results are shown in Table 6. (Evaluation Criteria) A (Excellent): 1.5 N / 15 mm or more B (Good): 1.0 N / 15 mm or more and less than 1.5 N / 15 mm C (Fair): 0.8 N / 15 mm or more and less than 1.0 N / 15 mm D (Poor): 0.5 N / 15 mm or more and less than 0.8 N / 15 mm E (Bad): Less than 0.5 N / 15 mm

[0133] (Recyclability Evaluation) Cut the packaging materials obtained in the above Examples and Comparative Examples into a size of 4 cm × 4 cm, wash them with water and dry them. Put the packaging material pieces into a single-screw extruder, melt and knead them at a screw rotation speed of 250 rpm and 220 °C, use a 150-mesh filter, and extrude them from the discharge part of the extrusion device at a pressure of 4 MPa. Then, immediately cut them with a pelletizer and immerse them in cold water for cooling. In this way, pellets of recycled plastic recycled from the packaging material were obtained. Then, the pellets of recycled plastic were each extruded and formed at 220 °C using a T-die extruder to produce a film-shaped molded body with a thickness of 50 μm. For the obtained film, count the number of foreign matters and foams distinguishable by visual inspection per 0.5 m 2 and evaluate them according to the following criteria. The evaluation results are shown in Table 6. A (Excellent): The number of foreign matters and foams is less than 40 B (Good): The number of foreign matters and foams is 40 or more and less than 80 C (Fair):: The number of foreign matters and foams is 80 or more and less than 120 D (Poor):: The number of foreign matters and foams is 120 or more and less than 200 E (Bad): The number of foreign matters and foams is 200 or more

[0134]

Table 6

Claims

1. A packaging material having a base material, a printing layer, an adhesive layer, and a sealant in this order, wherein the packaging material contains 80% by mass or more of a polyolefin resin, the arithmetic mean height Sa value defined in ISO 25178 of the surface of the printing layer is 0.1 to 1.3 μm, the surface of the printing layer and the adhesive layer are adjacent to each other, the adhesive layer is a cured product of a solventless adhesive containing a polyol (A) and a polyisocyanate (B), and the shear stress of the solventless adhesive under the following test conditions is 1.5 N or more. A packaging material. (Test conditions) Using the solvent-free adhesive, a coating amount of 1.9 to 2.1 g / m is applied onto the corona-treated surface of a polyethylene terephthalate substrate 1 with a thickness of 25 μm and a wetting tension of 45 to 60 mN / m on the corona-treated surface. ２ An adhesive layer with the above coating amount is formed, and the corona-treated surface of a polyethylene terephthalate substrate 2 with a thickness of 25 μm and a wetting tension of 45 to 60 mN / m on the corona-treated surface is bonded to form a test piece such that the bonding area is 25 mm × 25 mm. After holding the test piece at 20°C and 65% humidity for 1 hour, a tensile test of the substrate 1 and the substrate 2 of the test piece is performed in an 80°C environment, and the shear stress is measured.

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

3. The packaging material according to claim 1 or 2, wherein the viscosity at 40 ° C. measured according to JIS K5600-2-3 after blending the solventless adhesive at 40 ° C. and then standing still at 40 ° C. for 20 minutes is 6000 mPa·s or less.

4. The packaging material according to claim 1 or 2, wherein the polyol (A) contains a structural unit derived from a polyether polyol and / or a structural unit derived from a polyester polyol.

5. The packaging material according to claim 1 or 2, wherein the printing layer contains a pigment and a binder resin, and the chlorine content of the binder resin is 5% by mass or less.

6. The packaging material according to claim 5, wherein the content of the pigment is 30% by mass or less in the total mass of the printing layer.

7. The packaging material according to claim 1 or 2, wherein the chlorine content is 0.4% by mass or less in the total mass of the packaging material.

8. A method for manufacturing a packaging material having a base material, a printing layer, an adhesive layer, and a sealant in this order and containing 80% by mass or more of a polyolefin resin, a step of forming the printing layer having a surface with an arithmetic mean height Sa value defined in ISO 25178 of 0.1 to 1.3 μm on the base material, including a step of applying a solventless adhesive containing a polyol (A) and a polyisocyanate (B) to the surface of the printing layer, and the shear stress of the solventless adhesive under the following test conditions is 1.5 N or more. A method for manufacturing a packaging material. (Test conditions) Using the solventless adhesive, the coating amount is 1.9 to 2.1 g / m² on the corona-treated surface of the polyethylene terephthalate substrate 1 with a thickness of 25 μm and a wetting tension of 45 to 60 mN / m on the corona-treated surface. ２ The adhesive layer is formed, and the corona-treated surface of the polyethylene terephthalate substrate 2 with a thickness of 25 μm and a wetting tension of 45 to 60 mN / m on the corona-treated surface is bonded to form a test piece with a bonding area of 25 mm × 25 mm. After holding the test piece at 20°C and 65% humidity for 1 hour, a tensile test of the substrate 1 and the substrate 2 of the test piece is performed in an 80°C environment, and the shear stress is measured.

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