Laminate, packaging bag, lid material, and method for manufacturing laminate

Abstract

To provide a laminate which suppresses contraction of a laminate composed of a polyolefin base material layer when being heat sealed, when the laminate is heat sealed, is excellent in moldability even in a plurality of times of heat sealing, prevents generation of scratches of the surface of a transparent coat layer when being heat sealed, and enables confirmation of a color and a design of the inner layer of the laminate.SOLUTION: A laminate includes a heat seal layer, a base material layer, and a transparent coat layer on the outermost surface on a side opposite to the heat seal layer when being viewed from the base material layer, wherein the base material layer is a film containing a polyolefin resin, the transparent coat layer contains a binder resin and solid particles, the binder resin contains a crosslinked composition of acryl polyol or vinyl chloride-vinyl acetate copolymer, and an isocyanate compound, and the solid particles contain polyethylene oxide wax particles having an average particle diameter of 3 to 15 μm, and silica particles having an average particle diameter of 1 to 30 μm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate having a heat seal layer, a packaging bag, a lid material, and a method for producing the laminate. [Background technology]

[0002] In recent years, there has been growing international awareness of resource recycling and the worsening of waste problems in countries around the world. This has led to a demand for environmentally friendly plastic packaging materials for food, pharmaceuticals, etc., from the perspective of the 3Rs (recycle, reuse, reduce). One of the efforts to develop environmentally friendly packaging materials is to make packaging materials from the same recyclable material, i.e., mono-material packaging. For example, polyester-based or polyolefin-based materials are being considered as materials for mono-material packaging. As part of these efforts to move toward mono-material packaging, mono-material (single-material) packaging films and bags for food, confectionery, snacks, etc., food container lids, and container labels are being increasingly used to promote recycling and reduce environmental impact. These packaging bags and lids are sometimes sealed or bonded by fusing films together or between films and containers using heat-sealing agents, and multi-layer laminates containing a single-material film substrate and heat-sealing agents are used. However, in conventional laminates combining different materials, various materials were selected to improve the durability and strength of the packaging material, such as low-shrinkage, high-strength, and high-melting-point polyethylene terephthalate resin or nylon resin as the base material.However, with monomaterials, which are made from a single material, most of the materials in the multilayer body must be made up of polyolefin resins such as polyethylene and polypropylene to be compatible with heat-sealing materials.Since polyolefin resins, which serve as the base material, have a lower melting point and higher shrinkage than other resins, shrinkage of the base material occurs during the heat-sealing process, which can lead to problems such as folding or bending of the heat-sealed parts. In particular, with the current mainstream high-speed bag-making machines, laminated and printed raw laminate rolls are typically heat-sealed multiple times per packaging material in order to speed up the line and prevent leakage of contents from the heat-sealed parts.When mass-producing, the base material that has shrunk during heat sealing is further heated during heat sealing, which often results in problems during heat sealing, such as distortion of the formed packaging bag or bending of the heat-sealed parts.

[0003] Several methods have been proposed to avoid such problems that occur during heat sealing of polyolefins. Patent Document 1 is an invention relating to a laminate comprising a protective layer, a polyethylene substrate layer, and a sealant layer, and claims that by using a thermosetting resin or a resin with a melting point of 160°C or higher as the protective layer, heat resistance is achieved that suppresses appearance problems such as adhesion of the molten substrate to the heat seal bar and wrinkles in the heat-sealed area, and that print visibility is also excellent. However, as mentioned above, because polyolefin substrates are highly shrinkable substrates, there is a problem that when a heated heat seal bar is repeatedly pressed against the substrate to increase adhesion, the polyolefin substrate shrinks and distorts its shape, and the heat-sealed area in this distorted state can fold and become fused. Patent Document 2 is an invention of a multilayer film comprising a polyolefin resin layer, a layer containing an acid-modified olefin resin, and a layer made of a polyurethane coating agent; it describes how shrinkage during heat sealing is suppressed by co-extrusion lamination of a polyolefin resin with a specific melting point and melt flow rate and an acid-modified olefin resin containing a (meth)acrylic acid ester; and how the addition of a layer made of a polyurethane coating agent results in excellent suitability for packaging machines and excellent adhesion between the coating layer and the olefin film; and the examples show that there is no shrinkage, wrinkling, or peeling in the heat-sealed areas when vertical pillow packaging is performed. However, while this could solve problems that occur during heat sealing when the contents are placed inside and the heat seal is sealed in a single operation over a long period of time, as in pillow packaging, problems such as shrinkage and wrinkling can occur when heat sealing is performed by operating the heat seal bar multiple times, as in a high-speed bag making machine.Furthermore, the suppression of shrinkage in Patent Document 2 is an effect achieved by the resin properties, such as the melt flow rate and melting point, of the polypropylene film co-extrusion laminated with the acid-modified olefin resin that serves as the base material, so the choice of base material is limited. Patent Document 3 relates to a polypropylene resin composition containing a propylene polymer having a melting point of 150°C or higher, a propylene-α-olefin resin composition, and a specific shaped spherical silica or an organic antiblocking agent. It claims that laminating the polypropylene resin composition with polypropylene by melt extrusion produces a heat-resistant laminate with fewer white spots of the antiblocking agent and preventing the laminate from fusing to a heat seal bar. However, resin compositions containing particles tend to shrink compared to resins that do not. As with Patent Document 1, repeated application of a heated heat seal bar to enhance adhesion can cause the polyolefin substrate to shrink, distorting the shape and resulting in the heat-sealed area breaking and fusing. Patent Document 4 describes an invention for a heat-shrinkable plastic label with a surface coating layer and a specular gloss of 50 or less at a 60° angle. In the examples, the label is made by forming a coating layer on a heat-shrinkable polyester film using a coating agent containing acrylic resin, organically coated surface-treated silica, silicone oil, and oxidized polyethylene wax or fluororesin powder. The invention claims that this shrink label provides a container with excellent matte finish, slipperiness, and scratch resistance, and prevents labels from heat-sealing to each other in a hot bender after heat sealing. However, while this solves the problem of heat-sealing between label surfaces in heat-shrinkable films, it does not solve the problem of shrinkage during heat sealing because the label is designed to be heat-shrunk to fit the shape of the container. When heat-sealed using a high-speed bag-making machine, the heat-sealed portion can fold and fuse together as it shrinks. Furthermore, since the slipperiness is achieved by using silicone oil in combination with oxidized polyethylene wax or fluororesin powder, when heat-sealing is performed multiple times using a high-speed bag-making machine, there is a problem that the silicone oil bleeds through to the back, hindering sealing and contaminating the heat-seal bar.

[0004] Furthermore, various coating agents for protecting substrates, such as those disclosed in Patent Documents 1, 2 and 4, have been proposed. For example, Patent Document 5 discloses an invention relating to a coating agent for food packaging sheets to be applied to paper, nonwoven fabric, or woven fabric substrates, which provides excellent blocking resistance and heat seal strength by applying an aqueous dispersion containing resin microparticles (A) that are polymers of ethylenically unsaturated monomer (a) with a specific glass transition temperature and acid value, and also provides excellent food resistance, such as resistance to condiments such as ketchup and sauces, and resistance to microwave ovens. However, because this coating agent relates to an aqueous dispersion to be applied to paper, when applied to a polyolefin substrate, it cannot be applied uniformly to the substrate, and it does not solve the problem of high-shrinkage substrates, resulting in problems such as the heat-sealed area folding and fusing, and the coating agent fusing to the heat seal bar. Patent Document 6 discloses an invention for an exterior packaging material for an electricity storage device having a substrate layer, a substrate protective layer, a metal foil layer, and a sealant layer as the outermost layer opposite the substrate protective layer. The invention provides an exterior packaging material that leaves a heat-sealed mark after heat sealing by including polymer wax particles and a filler in the substrate protective layer. The examples describe that a discolored heat-sealed mark was obtained by including an acrylic polyol binder, a filler made of a cross-linked polycarbonate resin, and a polymer wax in a polypropylene substrate. However, because the substrate protective layer is an invention that leaves a heat-sealed mark, discoloration of the heat-sealed area is a problem for food bags, lids, and labels, and the material could not be used. Furthermore, Patent Document 7 discloses an invention of a matte coating agent containing an isocyanate-based crosslinking agent, a polyurethane resin with a specific storage modulus as a binder, and other binders, and further containing silica or wax, and claims to provide a matte coating agent with heat resistance that prevents the matte coating layer from peeling even when heated, and with little residual solvent. However, because the matte coating agent provides a translucent matte finish, it is inferior in design as a laminate, and when applied to a polyolefin substrate, it does not solve the problem of shrinkage during heat sealing, and there are problems with the heat-sealed portion folding and fusing, as well as the matte coating agent fusing to the heat seal bar. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2022 / 230812 [Patent Document 2] International Publication No. 2013 / 002176 [Patent Document 3] Japanese Patent Application Publication No. 2018-65922 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-345793 [Patent Document 5] Japanese Patent Publication No. 2022-16065 [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-195084 [Patent Document 7] Japanese Patent Application Publication No. 2022-95299 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the present invention provides a laminate, a packaging bag, a lid material, and a method for producing a laminate, which, when heat-sealing a laminate made of a polyolefin base layer, suppresses shrinkage of the laminate during heat-sealing, has excellent formability even when heat-sealed multiple times, does not cause scratches on the surface of the transparent coating layer during heat-sealing, and allows the color and design applied to the inner layer of the laminate to be confirmed. [Means for solving the problem]

[0007] The present inventors have found that the above object can be achieved by forming a laminate having a heat seal layer, a substrate layer which is a film containing a polyolefin resin, and a transparent coating layer on the outermost surface of the substrate layer opposite the heat seal layer, the transparent coating layer containing a binder resin containing a crosslinking composition of an acrylic polyol or a vinyl chloride-vinyl acetate copolymer and an isocyanate compound, and solid particles including oxidized polyethylene wax particles having a specific average particle size and silica particles having a specific average particle size, and have completed the present invention.

[0008] That is, the present invention is (1) A laminate having a heat seal layer, a base layer, and a transparent coating layer on the outermost surface of the base layer opposite to the heat seal layer, wherein the base layer is a film containing a polyolefin resin, the transparent coating layer contains a binder resin and solid particles, the binder resin contains a crosslinked composition of an acrylic polyol or a vinyl chloride-vinyl acetate copolymer with an isocyanate compound, and the solid particles contain oxidized polyethylene wax particles having an average particle size of 3 to 15 μm and silica particles having an average particle size of 1 to 30 μm. (2) The laminate of (1), wherein the oxidized polyethylene wax particles of (1) are oxidized polyethylene wax particles having an acid value of 0.5 to 50 mgKOH / g. (3) A laminate in which the acrylic polyol or the vinyl chloride-vinyl acetate copolymer according to (1) or (2) has a hydroxyl value of 20 to 250 mgKOH / g. (4) The laminate according to (1) or (2), wherein the thickness of the transparent coating layer is 0.3 to 8 μm. (5) A packaging bag formed from the laminate of (1) or (2). (6) A lid material formed from the laminate of (1) or (2). (7) A method for producing a laminate, comprising the steps of preparing a polyolefin resin as a substrate layer, laminating a heat-sealing agent or a heat-sealing film to form a heat-sealable laminate having a substrate layer and a heat-sealing layer, and applying a transparent coating agent to the outermost surface of the heat-sealable laminate opposite to the surface on which the heat-sealing agent or the heat-sealing film is laminated, as viewed from the substrate, to form a transparent coating layer, wherein the transparent coating agent contains a binder resin, solid particles, and an organic solvent, the binder resin contains a crosslinked composition of an acrylic polyol or a vinyl chloride-vinyl acetate copolymer with an isocyanate compound, and the solid particles are a transparent coating agent containing oxidized polyethylene wax particles having an average particle size of 3 to 15 μm and silica particles having an average particle size of 1 to 30 μm. It is related to. [Effects of the Invention]

[0009] According to the present invention, there are provided a laminate, a packaging bag, a lid material, and a method for producing a laminate, in which shrinkage of the laminate during heat sealing is suppressed when the laminate is heat-sealed using a polyolefin base material layer, the laminate has excellent formability even when heat-sealed multiple times, no scratches are generated on the surface of the transparent coating layer during heat sealing, and the color and design applied to the inner layer of the laminate can be confirmed. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that this embodiment is merely one embodiment for carrying out the present invention, and the present invention is not limited to this embodiment. Various modifications and embodiments are possible within the scope of the gist of the present invention. Furthermore, in this specification, the expression "a to b" in the description of a numerical range means a or more and b or less, unless otherwise specified. For example, "1 to 5 parts by weight" means "1 part by weight or more and 5 parts by weight or less."

[0011] The laminate of the present invention is a laminate comprising a heat seal layer, a base layer, and a transparent coating layer laminated on the outermost surface of the base layer opposite the heat seal layer, wherein the base layer is a film containing a polyolefin resin, the transparent coating layer contains a binder resin and solid particles, the binder resin contains a crosslinked composition of an acrylic polyol or a vinyl chloride-vinyl acetate copolymer with an isocyanate compound, and the solid particles contain oxidized polyethylene wax particles having an average particle size of 3 to 15 μm and silica particles having an average particle size of 1 to 30 μm. The laminate, packaging bag, lid material, and method for manufacturing the laminate can be provided, which suppresses shrinkage of the laminate during heat sealing when the laminate including the polyolefin base layer is heat sealed, has excellent formability even when heat sealed multiple times, does not cause scratches on the surface of the transparent coating layer during heat sealing, and allows the color and design applied to the inner layer of the laminate to be confirmed.

[0012] The laminate of the present invention, having the above-mentioned structure, can suppress shrinkage of the laminate caused by heat during heat sealing. These effects are thought to be due to the fact that when heat sealing is performed from the surface side of the transparent coating layer, the transparent coating layer prevents the heat generated during heat sealing from being transmitted to the base layer, and the transparent coating layer formed by the adhesive properties of the cross-linked material formed by mixing and applying the binder (acrylic polyol or vinyl chloride-vinyl acetate copolymer) with the isocyanate compound, and the polyethylene oxide and silica particles, prevents the shrinkage of the base layer containing polyolefin resin during heat sealing.

[0013] Each layer of the laminate and the components contained in each layer are described below.

[0014] [Transparent coating layer] The transparent coating layer in the laminate of the present invention is preferably transparent so that the color and design of the layer below the transparent coating layer can be seen, and the average light transmittance is preferably 80 to 99%, more preferably 85 to 99%, as measured in accordance with JIS K7361-1:1997.

[0015] The transparent coating layer is preferably formed by applying a transparent coating agent containing the components of the transparent coating layer and an organic solvent as a gravure printing method, or as a flexographic printing method, and then drying the applied transparent coating agent. The thickness of the transparent coating layer is preferably 0.3 to 8 μm, more preferably 0.4 to 6 μm, and even more preferably 0.5 to 5 μm. If the thickness of the transparent coating layer is less than 0.3 μm, the heat resistance of the laminate during heat sealing is poor, and if it is more than 8 μm, the transparency and blocking resistance when multiple laminates are stacked are poor.

[0016] The transparent coating layer contains the binder resin described below and solid particles.

[0017] [Solid particles] The solid particles include oxidized polyethylene wax particles and silica particles.

[0018] [Oxidized polyethylene wax particles] The average particle size of the oxidized polyethylene wax particles is preferably 3 to 15 μm, and more preferably 5 to 10 μm. The average particle size in the present invention refers to the D50 particle size measured using a measuring device based on the laser diffraction / scattering method, such as the laser diffraction / scattering particle size distribution measuring device LA-920 (manufactured by Horiba, Ltd.) or MICROTRAC 9320-X100 (manufactured by Honeywell).

[0019] The average particle diameter (D50) of the oxidized polyethylene wax particles is the above average particle diameter, and the ratio thereof to the thickness (T) of the transparent coating layer, (D50) / (T), is preferably 1.1 to 45, more preferably 1.2 to 20, and even more preferably 1.2 to 10. Within this range, the adhesiveness between the oxidized polyethylene wax particles and the binder resin works effectively, suppressing shrinkage of the laminate during heat sealing, while the oxidized polyethylene wax particles melted on the surface of the transparent coating layer during heat sealing repair scratches on the surface of the transparent coating layer during heat sealing, thereby preventing scratches during heat sealing and providing a laminate with excellent formability.

[0020] The oxidized polyethylene wax particles are preferably in the form of flakes or spheres. The melting point of the oxidized polyethylene wax particles is preferably 85 to 130°C.

[0021] Oxidized polyethylene wax particles are produced by subjecting polyethylene wax particles to an oxidation treatment, and have a polyethylene-derived skeleton (polyethylene skeleton). The polyethylene skeleton mainly has structural units derived from ethylene.

[0022] The acid value of the oxidized polyethylene wax particles is preferably 0.5 to 50 mgKOH / g, more preferably 5 to 30 mgKOH / g, and even more preferably 10 to 20 mgKOH / g. If the acid value of the oxidized polyethylene wax particles is less than 0.5 mgKOH / g, the laminate shrinks during heat sealing. If the acid value exceeds 50 mgKOH / g, the transparent coating agent thickens during the formation of the transparent coating layer, making it impossible to obtain a uniform transparent coating layer.

[0023] The concentration of the oxidized polyethylene wax particles is preferably 0.5 to 20%, more preferably 1 to 10%, based on the solid content of the transparent coating layer. If it is less than 0.5%, the laminate shrinks when heat-sealed, and if it is more than 20%, the transparency of the transparent coating layer is poor.

[0024] In order to improve the surface slip properties, the transparent coating layer of the laminate of the present invention may further contain non-oxidized general polymerization type polyethylene wax particles in addition to the oxidized polyethylene wax particles. In this case, it is preferable that the average acid value calculated from the weight ratio of the oxidized polyethylene wax particles to the non-oxidized general polymerization type polyethylene wax particles is within the above-mentioned acid value range, and it is preferable that the oxidized polyethylene wax accounts for 10 to 100% of the total amount of polyethylene wax particles. Examples of non-oxidizable general polymerized polyethylene wax particles include low-density polyethylene waxes such as Mitsui Chemicals' Hiwax 110P, 210P, 220P, and 410P, and high-density types such as Hiwax 100P, 200P, 400P, and 800P.

[0025] [Silica particles] The silica particles may be synthetic, naturally occurring, crystalline, non-crystalline, hydrophobic, hydrophilic, etc. The silica particles may be hydrophilic silica having hydrophilic functional groups on the surface, or may be hydrophobic silica that has been further modified to be hydrophobic. The average particle size of the silica particles is preferably 1.0 to 30 μm, more preferably 2.0 to 20 μm, and even more preferably 2.0 to 15 μm. If it is less than 1.0 μm, the heat shrinkability and transparency will be poor, and if it is more than 30 μm, the scratch resistance will be poor. The concentration of the silica particles is preferably 0.1 to 10%, more preferably 0.3 to 8%, and even more preferably 0.5 to 5% of the solid content of the transparent coating layer. If the concentration is less than 0.1%, the laminate will shrink during heat sealing, and if it is more than 10%, the transparency and scratch resistance of the transparent coating layer will be poor.

[0026] [Binder resin] The binder resin contained in the transparent coating layer is preferably a thermoplastic resin, and the glass transition temperature Tg of the binder resin is preferably 50 to 120° C. The binder resin refers to a thermoplastic resin that is soluble in an organic solvent and that serves as a binding function in the transparent coating agent or the like that is applied as the transparent coating layer.

[0027] The transparent coating layer of the present invention contains, as a binder resin, a crosslinked product of an acrylic polyol and an isocyanate compound, or a crosslinked product of a vinyl chloride-vinyl acetate copolymer and an isocyanate compound. The binder resin is prepared by dispersing each component in a liquid organic solvent to form a transparent coating agent, which is then applied to form the crosslinked product.

[0028] The binder resin may further contain at least one resin selected from the group consisting of (meth)acrylic resin, urethane resin, polyamide resin, soluble cellulose, chlorinated polyolefin resin, alkyd resin, cellulose-based resin (soluble cellulose, cellulose acetate propionate, cellulose acetate butyrate, etc.), vinyl acetate resin, rosin-based resin (rosin, hardened rosin, polymerized rosin, rosin ester, rosin-modified maleic acid resin, etc.), ketone resin, polybutyral resin, cyclized rubber-based resin, chlorinated rubber-based resin, petroleum resin, olefin-based resin, polyester resin, polylactic acid resin, etc., to the extent that it does not affect the heat resistance and shrinkage of the laminate. These resins may be prepared by conventional methods.

[0029] [Acrylic polyol] The acrylic polyol is preferably an acrylic polyol having a hydroxyl group, and the hydroxyl group undergoes a crosslinking reaction with the isocyanate compound described below to promote improvement of properties. The hydroxyl value of the acrylic polyol is preferably 20 to 250 mgKOH / g. If the hydroxyl value is less than 20 mgKOH / g, the binder cannot be sufficiently crosslinked, resulting in poor heat resistance of the transparent coating layer during heat sealing, while if the hydroxyl value is more than 250 mgKOH / g, the crosslinked product will gel, resulting in poor printability of the coating agent during printing of the transparent coating layer.

[0030] The acrylic polyol preferably has a glass transition temperature of 50 to 120° C. If the glass transition temperature of the acrylic polyol is less than 50° C., the heat resistance and blocking resistance of the laminate will be poor, and if it is more than 120° C., the adhesion of the transparent coating layer to the substrate will be poor. In the present invention, the glass transition temperature refers to a value measured by a differential scanning calorimeter (DSC), and the temperature at the inflection point of the baseline shift in the DSC measurement is the glass transition temperature.

[0031] The weight-average molecular weight of the acrylic polyol is preferably 20,000 to 150,000. If the weight-average molecular weight is less than 20,000, the heat resistance is poor, and if the weight-average molecular weight is more than 150,000, the printability of the transparent coating agent when printing the transparent coating layer is poor. The weight-average molecular weight is measured by GPC (gel permeation chromatography).

[0032] The method for synthesizing the acrylic polyol is not particularly limited, and known methods such as anionic polymerization, living anionic polymerization, cationic polymerization, living cationic polymerization, radical polymerization, and living radical polymerization of an acrylic monomer in the presence of an organic solvent can be used.

[0033] As an example of the acrylic monomer, a copolymer of a hydroxyl group-containing (meth)acrylic monomer and a hydroxyl group-free (meth)acrylic monomer is preferably used. The hydroxyl group-containing (meth)acrylic monomer may be any monomer containing one (meth)acryloyl group and one or more hydroxyl groups in one molecule.

[0034] Examples of the hydroxyl group-containing acrylic monomer include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate; caprolactone-modified (meth)acrylate; and hydroxyethyl acrylamide. The acrylic polyol preferably contains 1 to 30% by mass of structural units derived from hydroxyl group-containing acrylic monomers based on the total mass of the acrylic polyol.

[0035] Examples of the acrylic monomer not containing a hydroxyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, methylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate. The acrylic polyol preferably contains a structural unit derived from methyl methacrylate. The content of structural units derived from methyl methacrylate is preferably 5 to 60 mass % of the total mass of the acrylic polyol, and more preferably 10 to 50 mass %. The acrylic polyol preferably contains structural units derived from butyl methacrylate. The content of structural units derived from butyl methacrylate is preferably 30 to 70 mass % of the total mass of the acrylic polyol. It should be noted that (meth)acrylic, (meth)acrylate, and (meth)acryloyl mean acrylic and methacrylic, acrylate and methacrylate, and acryloyl and methacryloyl, respectively.

[0036] The acrylic monomer may also contain a carboxyl group-containing acrylic monomer, an amide bond group-containing acrylic monomer, an amino group-containing acrylic monomer, an alkylene oxide group-containing acrylic monomer, an epoxy group-containing acrylic monomer, or the like.

[0037] [Vinyl chloride-vinyl acetate copolymer] The weight-average molecular weight of the vinyl chloride-vinyl acetate copolymer is preferably 20,000 to 100,000, and more preferably 40,000 to 80,000. The vinyl chloride-vinyl acetate copolymer preferably contains 1 to 30% by mass of vinyl acetate monomer-derived structures, and 70 to 95% by mass of vinyl chloride monomer-derived structures. The glass transition temperature is preferably 50 to 90°C. Furthermore, the vinyl chloride-vinyl acetate copolymer preferably has a hydroxyl group capable of reacting with an isocyanate curing agent, and the hydroxyl value is preferably 20 to 250 mgKOH / g, more preferably 40 to 150 mgKOH / g, and even more preferably 60 to 100 mgKOH / g. If the hydroxyl value is less than 20 mgKOH / g, the binder will not be sufficiently crosslinked, resulting in poor heat resistance of the transparent coating layer during heat sealing. If the hydroxyl value is greater than 250 mgKOH / g, the crosslinked product will gel, resulting in poor printability of the coating agent during printing of the transparent coating layer. By forming a crosslinked product from a vinyl chloride-vinyl acetate copolymer having the above-mentioned hydroxyl value and an isocyanate curing agent, it is possible to obtain a laminate in which shrinkage is suppressed when heat-sealed by laminating a transparent coating agent of the crosslinked product having excellent adhesion to oxidized polyethylene wax particles and silica particles.

[0038] [Isocyanate compounds] Isocyanate compounds that can be used include aromatic diisocyanates such as tolylene diisocyanate and 4,4'-diphenylmethane diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 4,4'-dicyclohexyl diisocyanate, and pentane-1,5-diisocyanate (Stabio PDI), as well as modified versions of these compounds such as trimethylolpropane trimer, isocyanurate, biuret, and allophanate. Examples of diisocyanates include 0, TAE-100, TKA-100, P301-75E, E402-808, E405-70B, AE700-100, D101, D201, A201H (manufactured by Asahi Kasei Corporation), Mytec Y260A (manufactured by Mitsubishi Chemical Corporation), Coronate CORONATE HX, Coronate CORONATE HL, Coronate CORONATE L (manufactured by Tosoh Corporation), Desmodur N75MPA / X (manufactured by Bayer), and LG Hardener C (manufactured by Tokyo Ink Co., Ltd.). Of these, aliphatic diisocyanates are more preferred.

[0039] Regarding the concentration of the isocyanate compound, the solids weight ratio of the binder (B1) to the isocyanate compound (B2) in the transparent coating layer is preferably (B1) / (B2) = 60 / 40 to 99 / 1, more preferably (B1) / (B2) = 62 / 38 to 95 / 5. If (B1) / (B2) is greater than 99 / 1, the film may shrink during heat sealing, and if (B1) / (B2) is less than 60 / 40, blocking may occur when the printed material is wound into a roll during the coating process.

[0040] [Other components in the transparent coating layer] The transparent coating layer may also contain a release agent, a mold release agent, an inorganic filler, an organic filler, an antifoaming agent, a leveling agent, an antiblocking agent, a wax, a pigment dispersant, an antistatic agent, a slip agent, a plasticizer, a tackifier, a coloring material, etc. Any known and commonly used agent can be appropriately selected within a range that does not impair the transparency of the transparent coating layer and the properties of the laminate, such as shrinkability and moldability.

[0041] [Base material layer] The base layer preferably contains a polyolefin resin as a main component, and specific examples of the polyolefin resin include polyethylenes such as low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE), polypropylene, ethylene-propylene copolymers, α-olefin polymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, cyclic olefin resins, and modified olefin resins obtained by modifying polyolefin resins with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids. The thickness of the substrate layer is preferably 20 to 100 μm.

[0042] The substrate layer can be produced by forming a film using a conventionally known method such as an extrusion method, a cast molding method, a T-die method, a cutting method, or an inflation method. The substrate layer may be an unstretched film, or may be a film stretched uniaxially or biaxially using a tubular method, a T-die method, or the like, from the viewpoint of formability and strength of the substrate film, and one or more types of films may be laminated. The surface of the substrate layer may be subjected to a surface treatment such as corona treatment, low-temperature plasma treatment, flame treatment, ozone treatment, glow discharge treatment, solvent treatment, or coating treatment, or may be previously subjected to such a treatment.

[0043] The substrate layer may contain additives as needed. Specifically, for the purpose of improving processability, heat resistance, weather stability, mechanical properties, dimensional stability, slipperiness, mold releasability, flame retardancy, design, antifungal properties, electrical properties, etc., plastic compounding agents and additives such as elastomers, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and antifungal agents may be added. The amount of additive added is adjusted within a range that does not significantly impair the shrinkage, other performance properties, or recyclability of the substrate layer.

[0044] [Heat seal layer] The heat seal layer of the laminate of the present invention is preferably made of a polyolefin resin, and can be provided by a general forming method such as extrusion lamination, dry lamination, or emulsion coating. Examples of the polyolefin resin that can be used include ethylene-based resins such as low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-(meth)acrylic acid copolymer; blend resins of polyethylene and polybutene; and polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer. The heat-seal layer may contain or contain other components in addition to polyolefin resins. Examples of such components include thermoplastic resins such as vinylidene chloride, shellacs, rosins, rosin-modified maleic acid resins, rosin-modified phenolic resins, nitrocellulose, cellulose acetate, cellulose acetyl propionate, cellulose acetyl butyrate, chlorinated rubber, cyclized rubber, polyamide resins, vinyl chloride-vinyl acetate copolymers, polyester resins, ketone resins, butyral resins, chlorinated polypropylene resins, chlorinated polyethylene resins, chlorinated ethylene vinyl acetate resins, ethylene vinyl acetate resins, (meth)acrylic resins, urethane resins, ethylene-vinyl alcohol resins, styrene-maleic acid resins, casein, and alkyd resins. These resins may be used singly or in combination. Examples include those dissolved in solvents or water, or those dispersed in water, such as acrylic emulsions, urethane emulsions, ethylene-vinyl alcohol emulsions, and ethylene vinyl acetate emulsions.

[0045] The heat seal layer may be formed by previously applying a heat seal agent or by laminating a sealant film having a heat seal function.

[0046] Examples of the heat-sealing agent include thermoplastic resins such as polyethylene, vinylidene chloride, shellacs, rosins, rosin-modified maleic acid resins, rosin-modified phenolic resins, nitrocellulose, cellulose acetate, cellulose acetylpropionate, cellulose acetylbutyrate, chlorinated rubber, cyclized rubber, polyamide resin, vinyl chloride-vinyl acetate copolymer, polyester resin, ketone resin, butyral resin, chlorinated polypropylene resin, chlorinated polyethylene resin, chlorinated ethylene vinyl acetate resin, ethylene vinyl acetate resin, (meth)acrylic resin, urethane resin, ethylene-vinyl alcohol resin, styrene-maleic acid resin, casein, and alkyd resin, which may be used alone or in combination. Examples of the heat-sealing agent include those obtained by dissolving these resins in a solvent, or those obtained by dispersing them in water, such as acrylic emulsions, urethane emulsions, ethylene-vinyl alcohol emulsions, polyethylene emulsions, polypropylene emulsions, and ethylene vinyl acetate emulsions.

[0047] Examples of the sealant film include polyolefin films such as polyethylene, polypropylene, ethylene-vinyl acetate, and copolymers thereof, as well as co-extruded and colored films thereof, polystyrene films, polyacrylonitrile films, ethylene-vinyl alcohol resin films, and films coated with the heat sealing agent on a substrate. These films may be stretched or unstretched, and may be laminated with one or more types of films.

[0048] [Other laminates] The laminate of the present invention may have a printed layer, a transparent vapor deposition layer, a gas barrier coating layer, or a resin layer that can impart or enhance properties such as rigidity, stiffness, gas barrier properties, aroma retention, moisture resistance, pinhole resistance, dead hole resistance, light blocking properties, and straight line cutting properties between the transparent coating layer and the substrate layer or between the substrate layer and the heat seal layer.

[0049] The printing layer may be provided on the front side of the substrate layer, i.e., the side having the transparent coating layer as viewed from the substrate layer, on which the design of the laminate on the substrate layer can be confirmed, as a so-called front-printed type printing layer, or may be provided on the back side of the substrate layer, such as a transparent substrate layer, as a so-called back-printed type printing layer. The printed layer is preferably a layer made of gravure printing ink (hereinafter also referred to as ink), and is preferably formed by applying the gravure printing ink by gravure printing. In particular, it is more preferably formed by applying the gravure printing method using a multicolor gravure printing machine. Furthermore, since it is formed by applying the gravure printing method, not only full solid printing but also gradation printing and partial printing are possible. Furthermore, by using a printing machine with a reversing mechanism, a laminate having various other printed layers can be obtained.

[0050] In the laminate of the present invention, the thickness of the transparent coating layer is thinner than the thickness of the substrate layer, and therefore, by using polyolefin resin for the substrate layer and the heat seal layer, and by using polyolefin resin for preferably 80 wt %, more preferably 90 wt %, of the laminate, it is possible to obtain a mono-material resin laminate.

[0051] [Method of manufacturing laminate] The method for producing a laminate of the present invention includes the steps of preparing a polyolefin resin as a base layer, laminating a heat-sealing agent or a heat-sealing film to form a heat-sealable laminate having a base layer and a heat-sealing layer, and applying a transparent coating agent to the outermost surface of the heat-sealable laminate opposite to the surface on which the heat-sealing agent or the heat-sealing film is laminated, as viewed from the base, to form a transparent coating layer, and is characterized in that the transparent coating agent is used. The production method will be described in detail below.

[0052] In the method for producing a laminate of the present invention, the order of the step of forming the heat-sealable laminate and the step of applying the transparent coating agent can be set arbitrarily depending on the structure of the laminate to be obtained. For example, in the case where a printed layer is further provided between the base layer and the heat-sealable layer in the laminate by reverse printing, the heat-sealable laminate can be formed after the printed layer is formed, and then a transparent coating agent can be applied and dried to form the transparent coating layer. On the other hand, when a printed layer is provided between the substrate layer and the transparent coating layer by surface printing, after forming the printed layer, a transparent coating agent is applied and dried to form the transparent coating layer, and then a heat-sealable laminate can be formed.

[0053] The application step is preferably carried out by gravure printing, in which the transparent coating agent is applied as a gravure ink composition, or by flexographic printing, in which the transparent coating agent is applied as a flexographic ink composition, but is preferably carried out by gravure printing, which enables high-speed printing and significantly improves productivity. In the coating step, the transparent coating agent is preferably applied so that the thickness thereof becomes 0.3 to 8 μm after the drying step described below.

[0054] The transparent coating agent is prepared by dispersing binder resin and solid particles, which are components of the transparent coating layer, in an organic solvent, and is preferably applied as a gravure ink composition by gravure printing. Alternatively, the components other than the isocyanate compound contained in the transparent coating layer may be prepared in advance as ink, and an isocyanate curing agent may be prepared separately by dissolving the isocyanate compound in an organic solvent, and the ink and the isocyanate curing agent may be mixed immediately before application by gravure printing.

[0055] The organic solvent in the gravure ink composition may be a solvent typically used in gravure inks. Examples of the solvent include aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as hexane, cyclohexane, methylcyclohexane and ethylcyclohexane, alcohol solvents such as methanol, ethanol, isopropyl alcohol, normal propyl alcohol, 1-butanol, 2-butanol, isobutanol and tert-butanol, ester solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate and tert-butyl acetate, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether and ethylene glycol monomethyl ether. Examples of suitable solvents include glycol ether solvents such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether, as well as esters thereof. The esters are primarily acetated, such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. Among these, toluene, ethyl acetate, n-propyl acetate, isopropyl alcohol, methanol, propylene glycol monomethyl ether, and methyl ethyl ketone are more preferred from the standpoint of printability and versatility. These solvents can be used alone or in combination.

[0056] The viscosity of the gravure ink composition is not particularly limited as long as it does not interfere with printing. Considering the manufacturability and handling of the ink composition used in gravure printing, a viscosity of 10 to 1,000 mPa·s at 25°C is preferred. If the viscosity is less than 10 mPa·s, the ink will be too low, and the pigment will tend to settle out of the ink. If the viscosity is greater than 1,000 mPa·s, the ink will have poor flowability, causing problems during ink production and making it difficult to fill into containers. In this case, the viscosity can be measured using a commercially available viscometer such as a Brookfield viscometer or a cone-and-plate viscometer.

[0057] The gravure ink composition is preferably used in gravure printing, and can be applied as is, but can also be diluted with a diluting solvent in a Zahn Cup #3 (manufactured by Rigo Co., Ltd.) to adjust the viscosity to the desired level depending on the coating conditions and coating effect. In this case, the viscosity is preferably 10 to 40 seconds at 25°C. If the viscosity is less than 10 seconds, the ink tends to swim, and if it is more than 40 seconds, transferability during printing becomes poor.

[0058] In the step of forming the heat-sealable laminate, a heat-sealing agent may be applied to the substrate layer, or a heat-sealing film, so-called a sealant film, may be laminated on the substrate layer to form the heat-sealable laminate. In addition, if the laminate of the present invention has an intermediate layer between the substrate layer and the heat-sealing layer, the heat-sealing layer may be provided on the intermediate layer.

[0059] The heat sealing agent can be applied by a general forming method such as extrusion lamination, dry lamination, or emulsion application. As for the heat seal film (sealant film), as long as sufficient sealing strength can be ensured, the lamination method can be appropriately selected depending on the substrate, application, configuration, etc. For example, lamination with a sealant film (dry lamination, non-solvent lamination, wet lamination), lamination by heat (thermal lamination), resin coating by extrusion lamination (extrusion lamination, co-extrusion lamination, PE sandwich lamination), etc. are preferred, and the sealant film may also be bonded with an adhesive or pressure-sensitive adhesive.

[0060] The transparent coating layer is preferably applied to the entire surface of the laminate, but may also be applied to the periphery of the heat-sealed portion.

[0061] The packaging bag of the present invention is preferably formed from a laminate including the above-mentioned base material layer, a heat seal layer, and a transparent coating layer.

[0062] The packaging bag may be of any known type, such as two-sided seal, three-sided seal, four-sided seal, pillow seal, standing pouch, envelope seal, gusset, or weld seal.

[0063] The lid material of the present invention is preferably formed from a laminate including the above-mentioned base material layer, heat seal layer, and transparent coating layer. The lid material may be in any well-known form such as a cover, a lid, or a cap. [Example]

[0064] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" means "parts by weight" and "%" means "% by weight".

[0065] [Method of producing hydroxyl group-containing acrylic polyol HAP1] 54 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, 40 parts of butyl methacrylate, 150 parts of ethyl acetate, 100 parts of isopropyl alcohol, and 0.5 parts of azobisisobutyronitrile were added to a reaction vessel and mixed, and polymerization was carried out in a nitrogen gas atmosphere at 70°C for 8 hours to obtain acrylic polyol HAP1. The solids content of the resulting resin solution was 29%, and the hydroxyl value was 22 mgKOH / g.

[0066] [Method of producing hydroxyl group-containing acrylic polyol HAP2] 26 parts of methyl methacrylate, 50 parts of 2-hydroxyethyl methacrylate, 21 parts of butyl methacrylate, 150 parts of ethyl acetate, 100 parts of isopropyl alcohol, and 0.7 parts of azobisisobutyronitrile were added to a reaction vessel and mixed, and polymerization was carried out in a nitrogen gas atmosphere at 70°C for 8 hours to obtain acrylic polyol HAP2. The solids content of the obtained resin solution was 29%, and the hydroxyl value was 223 mgKOH / g.

[0067] [Vinyl chloride-vinyl acetate copolymer] Solbin AL (hydroxyl value 64 mgKOH / g) manufactured by Nissin Chemical Co., Ltd. was mixed with ethyl acetate to a solid content of 15%, and the mixture was stirred at 600 rpm for 10 minutes to prepare vinyl chloride-vinyl acetate copolymer CL1. Solbin TA5R (hydroxyl value 146 mgKOH / g) manufactured by Nissin Chemical Co., Ltd. was mixed with ethyl acetate to a solid content of 15%, and the mixture was stirred at 600 rpm for 10 minutes to prepare vinyl chloride-vinyl acetate copolymer CL2. Solbin C (hydroxyl value 0 mgKOH / g) manufactured by Nissin Chemical Co., Ltd. was mixed with ethyl acetate to a solid content of 15%, and the mixture was stirred at 600 rpm for 10 minutes to prepare vinyl chloride-vinyl acetate copolymer CL3.

[0068] [Oxidized polyethylene wax particles] Oxidized polyethylene wax (acid value 17 mgKOH / g, average particle size: 9 μm) was mixed with isopropyl alcohol to a solid content of 20% to prepare oxidized polyethylene wax particle dispersion OPW1. Also, oxidized polyethylene wax (acid value 17 mgKOH / g, average particle size: 15 μm) was mixed with isopropyl alcohol to a solid content of 20% to prepare oxidized polyethylene wax particle dispersion OPW2. Also, oxidized polyethylene wax (acid value 17 mgKOH / g, average particle size: 3 μm) was mixed with isopropyl alcohol to a solid content of 20% to prepare oxidized polyethylene wax particle dispersion OPW3. Also, oxidized polyethylene wax (acid value 17 mgKOH / g, average particle size: 2 μm) was mixed with isopropyl alcohol to a solid content of 20% to prepare oxidized polyethylene wax particle dispersion OPW4. Also, oxidized polyethylene wax (acid value 17 mgKOH / g, average particle size: 18 μm) was mixed with isopropyl alcohol to a solid content of 20% to prepare oxidized polyethylene wax particle dispersion OPW5.

[0069] Other raw materials used in the present invention are as follows: Silica Particles SL1 Product Name: AY-6A3, manufactured by Tosoh Silica Corporation, average particle size 6.5 μm, hydrophilic silica Silica Particles SL2 Product Name: ACEMATT HK440, manufactured by Evonik, average particle size 14.5 μm, precipitated silica Silica Particle SL3 Product Name: Nipsil SS-50F, manufactured by Tosoh Silica Corporation, average particle size 1.3 μm, hydrophobic silica Silica Particle SL4 Product Name: WACKER HDK H18, manufactured by Asahi Kasei Wacker Silicone Co., Ltd., average particle size 0.2 μm, dry process silica Polyurethane resin Product name: Sanprene IB-971, manufactured by Sanyo Chemical Industries, Ltd., solid content 30% Calcium Carbonate CC Product Name: Hakuenka DD, manufactured by Shiraishi Kogyo Co., Ltd. (average particle size 50 nm, rosin acid surface treatment) Polyethylene wax particles PW1 Product name: Hiwax 200P, manufactured by Mitsui Chemicals, oxidation state = 0 mg KOH / g, high density type Isocyanate compound Product name: LG Hardener D, manufactured by Tokyo Ink Co., Ltd. Solvent: Ethyl acetate, solid content 50% Organic solvent: Propyl acetate / isopropyl alcohol = 7:3 mixed solution

[0070] [Methods for measuring hydroxyl value, acid value, and average particle size] The hydroxyl value is the amount of hydroxyl groups in 1 g of resin calculated by acetylating the hydroxyl groups in the resin with an excess of an acetylating reagent and back-titrating the acid bonded to the hydroxyl groups with an alkali, and is converted into mg of potassium hydroxide, measured in accordance with JIS K0070. The acid value is the amount of hydroxyl groups in 1 g of resin calculated by back titrating the acid contained in 1 g of sample with alkali, converted into mg of potassium hydroxide, and is measured in accordance with JIS K0070. The average particle size was measured by particle size diffraction using a laser diffraction scattering method (laser diffraction / scattering particle size distribution measuring device, manufactured by HORIBA, "LA-960").

[0071] [Preparation of transparent coating agent g1] 70 parts of the prepared hydroxyl group-containing acrylic polyol HAP1 (solid content 35%), 26.5 parts of organic solvent, 2.5 parts of oxidized polyethylene wax particle dispersion OPW1, and 1 part by weight of silica particles SL1 were charged and stirred at 600 rpm with a stirrer for 10 minutes, and then 10 parts of an isocyanate curing agent solution was added to prepare transparent coating agent g1.

[0072] Similarly, as shown in Tables 1 and 2, transparent coating agents g2 to g9 and g11 to g20 were prepared.

[0073] [Table 1]

[0074] [Table 2]

[0075] [Create laminate] An engraved heliographic printing plate (compressed stylus 130°, 70 L / m) was attached to a GRAVO-PROOF (product number: CM-W, manufactured by Nissho Gravure Co., Ltd.). A 10 × 10 cm square pattern was solid-printed on a 20 μm-thick biaxially oriented polypropylene film (product name: P2271, manufactured by Toyobo Co., Ltd.) using black ink (product name: LG-FK920R Black, manufactured by Tokyo Ink Co., Ltd.) so that the film thickness upon solidification would be 1 μm to produce a printed layer. Further, transparent coating agent g1 was diluted with an organic solvent and adjusted to a viscosity of 17 seconds using a Zahn cup No. 3. After that, printing was performed so that the film thickness upon solidification would be 1 μm. After that, 30 μm of sealant GLC (manufactured by RM Tocello Co., Ltd., unstretched polypropylene film) was applied to obtain the laminate of Example 1. Similarly, as shown in Tables 3 and 4, the transparent coating agent and the film thickness of the transparent coating layer were changed to obtain laminates of Examples 2 to 11 and Comparative Examples 1 to 10, respectively. Furthermore, to serve as a standard for the evaluation of transparency described below, a 10 x 10 cm square pattern was solid-printed on the biaxially oriented polypropylene film using the black ink to create a printed layer with a thickness of 1 μm, and a laminate sample without a transparent coating layer was obtained.

[0076] From the obtained laminate, evaluation samples were prepared as follows. The prepared laminate was cut into a rectangle measuring 15 cm wide x 20 cm long, and two of the cut laminates were overlapped and heat-sealed three times with a 1-second interval using a heat seal tester at a temperature of 180°C, a pressure of 0.2 MPa, and a heating time of 0.3 seconds to seal two horizontal sides. Then, one vertical side was sealed under the same conditions to form the bottom, to prepare a three-sided sealed evaluation sample.

[0077] The evaluation samples thus prepared were evaluated by the following evaluation methods, and samples with all evaluation results of ◯ were determined to be good products.

[0078] [Evaluation of the surface condition of the transparent coating layer after repeated heat sealing] The heat-sealed portion of the prepared evaluation sample was inspected visually and with a magnifying glass on the surface of the transparent coating layer side, and the results are shown in Tables 3 and 4. ◯: No scratches caused by the heat seal bar being removed were observed visually or with a magnifying glass. △: Scratches caused by the heat seal bar being removed are not visible to the naked eye, but are visible when observed with a magnifying glass. ×: Damage caused by the heat seal bar being removed can be visually confirmed.

[0079] [Evaluation of shrinkage of packaged material during repeated heat sealing] The dimensional ratios of the rectangular evaluation samples were measured at three locations in the horizontal direction and three locations in the vertical direction (a total of six locations) to evaluate distortion due to shrinkage. The results are shown in Tables 3 and 4. ○: The dimensional ratios of all six points are within 1%. △: Any one of the dimensional ratios at six points is greater than 1% and less than 3%. ×: Any of the dimensional ratios at six locations is 3% or more.

[0080] [Evaluation of wrinkles after repeated heat sealing] The heat-sealed portions of the evaluation samples were visually inspected and evaluated, and the results are shown in Tables 3 and 4. O: No wrinkles. △: Partially wrinkled. ×: Overall.

[0081] [Transparency evaluation] The patterns of the printed layer of the evaluation samples were visually inspected by five evaluators from the surface of the transparent coating layer side of the evaluation samples, and the transparency was evaluated by determining whether the gloss was equal to or greater than that of a laminate sample without a transparent coating layer (hereinafter referred to as the reference sample). The results are shown in Tables 3 and 4. Good: All five evaluators judged it to have the same or better gloss. △: One or two of the evaluators judged the gloss to be inferior. ×: Three or more of the evaluators judged the gloss to be poor.

[0082] [Evaluation of blocking resistance] The evaluation sample was cut into a size of 3 x 3 cm, and the transparent coating layer side and the heat seal layer side were overlapped and subjected to 500 g / cm 2 at 50°C for 24 hours. 2 After applying a load of 1000 kJ / cm, the peel resistance when the transparent coating layer surface and the heat seal layer surface were peeled off and the peeling state of the transparent coating layer were observed and evaluated. The results are shown in Tables 3 and 4. ◯: No peeling resistance, and no peeling of the transparent coating layer. ×: Peeling resistance was observed, and peeling of the transparent coating layer was also observed.

[0083] [Table 3]

[0084] [Table 4]

Claims

1. A laminate having a heat seal layer, a base layer, and a transparent coating layer on the outermost surface of the base layer opposite to the heat seal layer, the substrate layer is a film containing a polyolefin resin, the transparent coating layer contains a binder resin and solid particles, the binder resin includes a crosslinked composition of an acrylic polyol or a vinyl chloride-vinyl acetate copolymer and an isocyanate compound; The solid particles include oxidized polyethylene wax particles having an average particle size of 3 to 15 μm and silica particles having an average particle size of 1 to 30 μm. Laminate.

2. 2. The laminate according to claim 1, wherein the oxidized polyethylene wax particles have an acid value of 0.5 to 50 mgKOH / g.

3. 3. The laminate according to claim 1, wherein the acrylic polyol or the vinyl chloride-vinyl acetate copolymer has a hydroxyl value of 20 to 250 mgKOH / g.

4. 3. The laminate according to claim 1, wherein the transparent coating layer has a thickness of 0.3 to 8 μm.

5. A packaging bag formed from the laminate according to claim 1 or 2.

6. A lid material formed from the laminate according to claim 1 or 2.

7. a step of preparing a polyolefin resin as a base layer; and a step of laminating a heat-sealing agent or a heat-sealing film to form a heat-sealable laminate having the base layer and the heat-sealing layer; a coating step of applying a transparent coating agent to the outermost surface of the heat-sealable laminate opposite to the surface on which the heat-sealing agent or heat-sealing film is laminated, as viewed from the substrate, to form a transparent coating layer, the transparent coating agent includes a binder resin, solid particles, and an organic solvent; the binder resin includes a crosslinked composition of an acrylic polyol or a vinyl chloride-vinyl acetate copolymer and an isocyanate compound; the solid particles are a transparent coating agent containing oxidized polyethylene wax particles having an average particle size of 3 to 15 μm and silica particles having an average particle size of 1 to 30 μm; A method for producing a laminate, characterized in that:

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