Laminated film, method for manufacturing the same, packaging material, and deinking method

Abstract

The object of the present invention is to provide a laminated film or packaging material that is made of a single material and does not require an adhesive layer made of a different material, yet is excellent in heat sealability, tear resistance, and recyclability. The present invention is a laminated film having a portion in which a varnish layer containing an acrylic resin, a polyurethane resin, a polyester resin and / or an epoxy resin, an ink layer, and an unoriented polyolefin film are in contact in this order.

Description

[Technical Field]

[0001] The present invention relates to a laminated film, a method for manufacturing the same, a packaging material, and a deinking method. [Background technology]

[0002] With the global population increasing, demand for flexible packaging used for food and daily necessities is expected to continue to grow. Flexible packaging materials are generally laminates with a base material that has excellent dimensional stability and a heat-sealable layer, and are often composed of different materials depending on the functionality. In recent years, from the perspective of protecting the global environment, material recycling methods for various packaging materials have attracted attention, and there is a demand for monomaterial packaging materials made of the same type of material that do not require sorting during recycling.

[0003] As such a packaging material, for example, a polyethylene laminate for packaging materials (see, for example, Patent Document 1) has been proposed, which comprises at least a stretched polyethylene film, an adhesive layer, and a heat-sealable polyethylene layer, wherein the adhesive layer contains a solvent-free adhesive. When producing packaging materials from a polyethylene laminate, it is common to include a heat-sealing process in which the heat-sealable polyethylene layer and sealant layer are placed facing each other and heat-sealed by heating and pressurizing them with a heat-sealing jig. In the case of the laminate described in Patent Document 1, the stretched polyethylene film is heated to a high temperature during heat sealing, which has resulted in problems with heat sealability, such as fused material adhering to the heat-sealing bar or wrinkles forming in the heat-sealed area.

[0004] Therefore, a laminate has been proposed (see, for example, Patent Document 2) having a structure in which a protective layer, a base layer, and a sealant layer are laminated in this order, wherein the base layer and the sealant layer contain polyethylene, the protective layer contains a thermosetting resin or a resin with a melting point of 160°C or higher, and the proportion of polyethylene in the laminate is 90% by mass or more. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-189333 [Patent Document 2] Japanese Patent Publication No. 2023-105431 [Overview of the project] [Problems that the invention aims to solve]

[0006] The laminate described in Patent Document 2 can improve heat resistance and heat sealability by providing a protective layer on the outermost layer that is heated to a high temperature during heat sealing.

[0007] However, the laminates described in Patent Documents 1 and 2 use a polyethylene film (base layer) and a flexible, heat-sealable polyethylene layer (sealant layer), requiring an adhesive layer for bonding the two. Removal of the adhesive layer is necessary for recycling, and there is room for further improvement in recyclability. In addition, when laminated films are used as packaging materials, they need to be resistant to tearing from impacts such as drops in order to protect the contents.

[0008] Therefore, the objective of the present invention is to provide a laminated film or packaging material made of a single material that does not require an adhesive layer made of different materials, yet is excellent in heat sealability, tear resistance, and recyclability. [Means for solving the problem]

[0009] To solve the above problems, the present invention mainly has the following configuration. (1) A laminated film having portions in which a varnish layer, an ink layer, and an unstretched polyolefin film are in contact in this order, comprising an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin. (2) A laminated film having a portion in which a varnish layer, an ink layer, a deinking layer, and an unstretched polyolefin film are in contact in this order, comprising an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin. (3) A packaging material having a portion in which a varnish layer, an ink layer, and an unstretched polyolefin film are in contact in this order, comprising an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin. (4) A packaging material having a portion in which a varnish layer, an ink layer, a deinking layer, and an unstretched polyolefin film are in contact in this order, comprising an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin. [Effects of the Invention]

[0010] The laminated film and packaging material according to the present invention are made of a single material that does not require an adhesive layer made of different materials, yet they have excellent heat sealability, are tear-resistant, and are highly recyclable. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. In this invention, "greater than or equal to" means the same as or greater than the numerical value shown. Also, "less than or equal to" means the same as or less than the numerical value shown.

[0012] A first aspect of the present invention is a laminated film having portions in which a varnish layer, an ink layer, and an unoriented polyolefin film are in contact in this order, and a second aspect of the present invention is a laminated film having portions in which a varnish layer, an ink layer, a deinking layer, and an unoriented polyolefin film are in contact in this order. In the laminated films of the first and second aspects (hereinafter sometimes collectively referred to as "the laminated films of the present invention"), the varnish layer contains an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin, and has the effect of physically protecting the unoriented polyolefin film and the ink layer, improving heat resistance during heat sealing and improving heat sealability, and imparting gloss or matte properties to the laminated film. The ink layer has the effect of imparting design properties to the laminated film. The unoriented polyolefin film has the effect of acting as a substrate for forming the printed layer and as a sealant during bag making. The deinking layer has the effect of separating the unoriented polyolefin film from the other layers by dissolving in an alkaline aqueous solution. The laminated film of the present invention has a so-called surface-printed configuration, having areas where a varnish layer, an ink layer, and an unoriented polyolefin film are in contact in that order, or areas where a varnish layer, an ink layer, a deinking layer, and an unoriented polyolefin film are in contact in that order. Such areas may be present only partially; for example, in non-image areas where there is no ink layer, the varnish layer and the unoriented polyolefin film may be in contact, or the varnish layer, the deinking layer, and the unoriented polyolefin film may be in contact. From the viewpoint of recyclability and reduction of the number of manufacturing steps described later, it is preferable that the laminated film of the present invention consists only of these layers and does not have any other layers.

[0013] Generally, polyolefins have a melting point in the range of 100°C to 160°C, and therefore melt under typical heat sealing conditions. However, when an unoriented polyolefin film comes into direct contact with a heat sealing jig, the contact area melts, which can easily lead to cosmetic defects such as wrinkles in the laminated film, or adhesion of the molten polyolefin film to the heat sealing jig, resulting in insufficient heat sealing performance. The laminated film of the present invention has a varnish layer, and when two unoriented polyolefin films are heat-sealed facing each other, the varnish layer protects the unoriented polyolefin film from the heat sealing jig, resulting in excellent heat sealing performance.

[0014] In the laminated film of the present invention, the unoriented polyolefin film serves both as a substrate for forming the printing layer and as a sealant during bag making, thus eliminating the need for an adhesive layer made of a different material to bond the substrate and the sealant. This improves recyclability. Furthermore, since the formation of an adhesive layer is not required in the manufacturing of the laminated film, the number of manufacturing steps can be reduced. In the present invention, the flexible unoriented polyolefin film can also function as a substrate by increasing its rigidity through electron beam irradiation, as described later, thereby suppressing tearing of the laminated film.

[0015] A third aspect of the present invention is a packaging material having a portion in which a varnish layer, an ink layer, and an unoriented polyolefin film are in contact in this order, and a fourth aspect of the present invention is a packaging material having a portion in which a varnish layer, an ink layer, a deinking layer, and an unoriented polyolefin film are in contact in this order. In the packaging materials of the third and fourth aspects (hereinafter sometimes collectively referred to as "the packaging materials of the present invention"), the varnish layer contains an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin, and has the effect of physically protecting the unoriented polyolefin film and the ink layer, improving heat resistance during heat sealing and improving heat sealability, and imparting gloss or matte properties to the packaging material. The ink layer has the effect of imparting design properties to the packaging material. The unoriented polyolefin film has the effect of acting as a substrate for forming the printed layer and as a sealant during bag making. The deinking layer has the effect of separating the unoriented polyolefin film from the other layers by dissolving in an alkaline aqueous solution. The packaging material of the present invention, like the laminated material of the present invention, has a so-called surface-printed structure. For example, in non-image areas where there is no ink layer, the varnish layer and the unstretched polyolefin film may be in contact, or the varnish layer, the deinking layer, and the unstretched polyolefin film may be in contact. The packaging material of the present invention, like the laminated material of the present invention, has excellent heat-sealability and is resistant to tearing. From the viewpoint of recyclability and reduction of the number of manufacturing steps, it is preferable that the packaging material of the present invention consists only of these layers and does not have any other layers.

[0016] First, each layer constituting the laminated film and packaging material of the present invention will be described.

[0017] (Unstretched polyolefin film) Since the non-stretched polyolefin film is not stretched, it is easy to stretch, and imparts high flexibility to the laminated film and the packaging material of the present invention, and can suppress breakage. In the present invention, as described later, it is preferable that the non-stretched polyolefin film is irradiated with an electron beam. Since the rigidity of the electron beam-irradiated part of the electron beam-irradiated non-stretched polyolefin film becomes high, the rigidity of the laminated film and the packaging material can be moderately increased, and sufficient toughness strength as a packaging material can be imparted.

[0018] Examples of the non-stretched polyolefin film include a non-stretched polypropylene film, a non-stretched polyethylene film, and the like. From the viewpoint of increasing the tensile elastic modulus and heat resistance of the laminated film and the packaging material of the present invention, a non-stretched polypropylene film is preferable, and from the viewpoint of further suppressing breakage, a non-stretched polyethylene film is preferable.

[0019] Examples of the polyethylene resin constituting the non-stretched polyethylene film include linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), and the like. Two or more of these may be used.

[0020] In addition, as the polyethylene resin, a copolymer of ethylene and another monomer can also be used. As the other monomer, an α-olefin having 3 to 20 carbon atoms is preferable, and examples thereof include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 3-methyl-1-butene, 4-methyl-1-pentene, and the like. Two or more of these may be used. Examples of the copolymer include a random copolymer and a block copolymer.

[0021] Examples of polypropylene resins that constitute the unoriented polypropylene film include propylene homopolymers and copolymers of propylene and other monomers. Preferred other monomers are α-olefins having 2 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 3-methyl-1-butene, and 4-methyl-1-pentene. Two or more of these may be used. Examples of copolymers include random copolymers and block copolymers.

[0022] Furthermore, the polyethylene resin or polypropylene resin that constitutes the unstretched polyolefin film may be mechanically recycled, a type of material recycling, or biomass-derived.

[0023] Mechanical recycling is a method in which recovered polyolefin film is crushed, alkaline washed to remove surface dirt and foreign matter, treated at high temperature and reduced pressure for a certain period, contaminants in the recycled material are removed by melt filtration, and the material is returned to polyolefin resin.

[0024] Since biomass-derived polyolefins are carbon-neutral materials, they can reduce the environmental impact during the manufacture of laminated films and packaging materials. Biomass-derived polyolefins, for example, in the case of polyethylene resin, can be manufactured by methods such as those described in Japanese Patent Publication No. 2013-177531. Alternatively, commercially available biomass-derived polyethylene (for example, "I'm green®" derived from sugarcane, commercially available from Braskem) or biomass-derived polypropylene (for example, "PRASUS®" manufactured by Prime Polymer Co., Ltd.) may be used.

[0025] Unoriented polyolefin films may contain various antioxidants, light stabilizers, and crosslinking agents. The inclusion of antioxidants and light stabilizers can suppress yellowing and oxidation. The inclusion of crosslinking agents promotes the crosslinking reaction during electron beam irradiation, as described later, thereby increasing the degree of crosslinking of the unoriented polyolefin film, moderately increasing the rigidity of the laminated film and packaging material, and making it more resilient.

[0026] Examples of antioxidants include phenolic antioxidants, phosphate-based antioxidants, sulfur-based antioxidants, hinderedamine-based antioxidants, and hydroxylamine-based antioxidants.

[0027] Examples of light stabilizers include UV absorbers such as benzotriazole-based UV absorbers, triazine-based UV absorbers, and benzophenone-based UV absorbers.

[0028] Examples of crosslinking agents include styrene-based elastomers such as styrene-isoprene rubber, styrene-butadiene rubber, and styrene-isoprene-butadiene rubber, as well as ethylene-acrylate copolymers and ethylene-acrylate-glycidyl methacrylate copolymers.

[0029] From the viewpoint of ensuring the tensile modulus of the laminated film is within the preferred range described later, the tensile modulus of the unoriented polyolefin film as defined in JIS K 7127:1999 is preferably 200 MPa or higher in both the MD and TD directions, and more preferably 400 MPa or higher. Furthermore, from the viewpoint of ensuring the tensile elongation at break of the laminated film is within the preferred range described later, the tensile elongation at break as defined in JIS K 7127:1999 is preferably 100% or higher in both the MD and TD directions, and more preferably 200% or higher.

[0030] The thickness of the unoriented polyolefin film is preferably 20 μm or more, and more preferably 40 μm or more, from the viewpoint of providing sufficient stiffness as a packaging material. On the other hand, the thickness of the unoriented polyolefin film is preferably 50 μm or less, from the viewpoint of reducing the amount of plastic used and further reducing the environmental impact.

[0031] It is preferable that the unoriented polyolefin film has been subjected to surface treatments such as corona treatment, burning treatment, or plasma treatment, which can improve its wettability and adhesion to the ink layer.

[0032] (Varnish layer) The varnish layer is characterized by containing acrylic resin, polyurethane resin, polyester resin, and / or epoxy resin. Because these resins have excellent heat resistance, they improve heat resistance during heat sealing, suppress adhesion of fused material to the heat seal bar and the formation of wrinkles in the heat-sealed area, thereby improving heat sealability. Furthermore, their high mechanical strength improves the abrasion resistance of the varnish layer.

[0033] Among these resins, acrylic resins formed by cross-linking polyfunctional (meth)acrylates are preferred. They have high mechanical strength, increasing the rigidity of laminated films and packaging materials, and making them more resilient. Furthermore, their high glass transition temperature and excellent heat resistance allow for improved heat sealability.

[0034] Acrylic resins can be obtained by crosslinking reactions of polyfunctional (meth)acrylates having two or more (meth)acryloyl groups. Among the polyfunctional (meth)acrylates, examples of difunctional (meth)acrylates having two (meth)acryloyl groups include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, bisphenol A di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and tripropylene glycol Examples include chol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, diglycerin di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, and tricyclodecanedimethanol di(meth)acrylate. Examples of trifunctional (meth)acrylates having three (meth)acryloyl groups include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, isocyanuric acid tri(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate. Examples of tetrafunctional (meth)acrylates having four (meth)acryloyl groups include ditrimethylolpropanetetra(meth)acrylate, diglycerintetra(meth)acrylate, and ditrimethylolpropanetetra(meth)acrylate. Examples of pentafunctional or more (meth)acrylates having five or more (meth)acryloyl groups include dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate. Two or more of these may be used.

[0035] The acrylic resin may have alkylene oxy groups derived from ethylene oxide or propylene oxide, or hydroxyalkylene oxy groups or hydroxypoly(alkylene oxy) groups derived from polyoxyethylene glycerin ether, etc.

[0036] The varnish layer may further contain alumina particles, titania particles, silica particles, and / or zirconia particles. By including these, the thermal conductivity of the varnish layer can be reduced and adjusted to a preferred range described later, allowing for heat sealing at higher temperatures and further improving heat sealability. It can also increase rigidity.

[0037] The total content of alumina particles, titania particles, silica particles, and zirconia particles in the varnish layer is preferably 0.5% by mass or more. This further reduces the thermal conductivity of the varnish layer and adjusts it to the preferred range described later, allowing for heat sealing at higher temperatures and improving heat sealability. It also makes the layer more rigid. On the other hand, the total content of alumina particles, titania particles, silica particles, and zirconia particles is preferably 3.0% by mass or less. This moderately increases the thermal conductivity of the varnish layer and adjusts it to the preferred range described later, allowing for heat sealing at lower temperatures and thus improving heat sealability. It also suppresses the thickening of the varnish that constitutes the varnish layer, maintaining a good appearance of the varnish layer.

[0038] Furthermore, while there are no particular limitations on the dispersion state of the particles in the varnish layer, a state in which the particles are dispersed in the resin is preferred. When heat conduction paths are formed by particle aggregation, the thermal conductivity may increase. As a method for evaluating the dispersion state of particles in the varnish layer, since the dispersion state of particles in the varnish before curing correlates with the dispersion state of particles in the varnish layer, one method is to measure the particle size distribution of the varnish before curing by dynamic light scattering and determine the presence or absence of aggregates.

[0039] The particle diameter of the aforementioned particles is preferably between 10 nm and 200 nm, from the viewpoint of suppressing light scattering and improving transparency. The particle diameter refers to the primary particle diameter or, if aggregated, the particle diameter in the aggregated state. The average particle diameter refers to the D50 value in the measurement of particles by laser diffraction and light scattering.

[0040] Examples of varnishes that make up the varnish layer include so-called heat-drying varnishes such as solvent varnishes and water-based varnishes, and active energy ray curing varnishes that harden when exposed to active energy rays. Among these, active energy ray curing varnishes require less energy to harden than heat-drying varnishes, thus further reducing the burden on the environment.

[0041] A heat-drying varnish contains the aforementioned resin and a solvent or water, and by drying and removing the solvent or water, a varnish layer containing the aforementioned resin is formed. In the case of a water-based varnish, it is preferable that the aforementioned resin is dispersed in an aqueous system in a self-emulsifying or surfactant-emulsifying form.

[0042] The active energy ray curing varnish contains the aforementioned polyfunctional (meth)acrylate, which undergoes radical crosslinking by active energy rays to form a varnish layer containing acrylic resin. In the electron beam irradiation described later, the polyfunctional (meth)acrylate crosslinks with the film at the contact surface with the unoriented polyolefin film, or in the case where a portion penetrates the unoriented polyolefin film, thereby increasing the rigidity of the laminated film and packaging material, making it stronger. Electron beams are preferred as the active energy rays, as their high penetration depth allows them to penetrate deep into the varnish and promote the crosslinking reaction.

[0043] The varnish layer preferably contains wax along with the aforementioned resin, which can improve abrasion resistance and slipperiness.

[0044] A thermal conductivity of 0.15 W / m·K or higher is preferable for the varnish layer, as it facilitates heat transfer to the unoriented polyolefin film during heat sealing, enabling heat sealing at lower temperatures and further improving heat sealability. On the other hand, a thermal conductivity of 0.23 W / m·K or lower, and more preferably 0.20 W / m·K or lower, is preferable for the varnish layer, as it suppresses melting of the unoriented polyolefin film during heat sealing, enabling heat sealing at higher temperatures and further improving heat sealability.

[0045] Here, the thermal conductivity of the varnish layer can be measured by the heat flow meter method using a thermal conductivity meter (HC-074 / 600, manufactured by Eiko Seiki) in accordance with JIS A 1412-2:1999. Since the curing conditions of the varnish layer do not affect the thermal conductivity as long as it is sufficiently cured, the varnish constituting the varnish layer can also be cured and measured. In this case, the varnish is evenly placed in an aluminum petri dish to a sample height of approximately 0.2 mm, cured by heating or electron beam irradiation to produce a cured film of approximately 0.2 mm thickness, and measured by the heat flow meter method described above. Preferred curing conditions are heating at 100°C for 3 hours for heat-drying varnishes, and an acceleration voltage of 250 kV and an irradiation dose of 300 kGy for electron beam curing varnishes.

[0046] Means for adjusting the thermal conductivity of the varnish layer to the above range include, for example, selecting a resin with low thermal conductivity, such as acrylic resin, as the resin for the varnish layer, and introducing voids into the varnish layer to improve its heat insulation properties. Methods for introducing voids into the varnish layer include, for example, dispersing particles such as alumina particles, titania particles, silica particles, and zirconia particles in the varnish layer in the aforementioned preferred amounts.

[0047] The melting temperature of the varnish layer is preferably 200°C or higher, and adhesion to the seal bar can be suppressed within a range below 200°C, which is the typical setting temperature for heat seal bars.

[0048] Here, the melting temperature of the varnish layer can be determined by placing a sample taken from the varnish layer in an aluminum petri dish, heating it in an oven at a predetermined temperature for 10 minutes, and then tilting the aluminum petri dish to visually observe whether or not there is any flow. If no flow is observed, it is determined that the melting temperature is above that temperature. Note that the curing conditions of the varnish layer do not affect the melting temperature as long as it is sufficiently cured, so it is also possible to measure the melting temperature after curing the varnish that makes up the varnish layer. In this case, a cured film with a thickness of approximately 0.2 mm is prepared, similar to the measurement of thermal conductivity described above, and the melting temperature is determined by the method described above.

[0049] The thickness of the varnish layer is preferably 1.5 μm or more, which can improve the tensile modulus, heat resistance, bag breakage resistance, and abrasion resistance of the laminated film and packaging material. It is more preferably greater than 5.0 μm, and even more preferably 5.1 μm or more. On the other hand, the thickness of the varnish layer is preferably 10.0 μm or less, which allows for sufficient drying and curing.

[0050] (Ink layer) In the laminated film and packaging material of the present invention, the ink layer refers to the state in which ink has been printed on the unoriented polyolefin film and then fixed to the unoriented polyolefin film by drying or curing.

[0051] From a design perspective, typical inks are colored inks containing pigments or dyes and binders. Examples include heat-drying inks such as solvent inks and water-based inks, oxidative polymerization type oil-based inks, and active energy ray curing inks that harden upon irradiation with active energy rays.

[0052] Among these, electron beam curable inks containing a polyfunctional (meth)acrylate as a binder are preferred. That is, it is preferable that the ink layer contains an acrylic resin which is the cured product of the electron beam curable ink. Since such an ink layer has high mechanical strength, the abrasion resistance of the ink layer can be improved. In addition, since electron beam curable inks require less energy to cure than heat-drying inks, the environmental burden can be further reduced. Furthermore, when the varnish layer is composed of an electron beam curable varnish, the varnish layer and the ink layer can be formed simultaneously by simultaneous irradiation with electron beams.

[0053] Examples of acrylic resins included in the ink layer include those exemplified as acrylic resins included in the varnish layer. Other resins may also be included along with the acrylic resin.

[0054] Examples of pigments include phthalocyanine pigments, soluble azo pigments, insoluble azo pigments, lake pigments, quinacridone pigments, isoindoline pigments, surene pigments, metal complex pigments, titanium dioxide, zinc oxide, alumina white, calcium carbonate, barium sulfate, talc, red iron oxide, cadmium red, lead yellow, zinc yellow, Prussian blue, ultramarine blue, oxide-coated glass powder, oxide-coated mica, oxide-coated metal particles, aluminum powder, gold powder, silver powder, copper powder, zinc powder, stainless steel powder, nickel powder, organic bentonite, iron oxide, carbon black, graphite, etc. Two or more of these may be included.

[0055] From the viewpoint of improving print density, the thickness of the ink layer is preferably 0.1 μm or more. On the other hand, from the viewpoint of ensuring sufficient drying and curing, the thickness of the ink layer is preferably 5.0 μm or less.

[0056] (Deinking layer) The laminated film and packaging material of the present invention, by having a deinking layer, allows for the separation of the unoriented polyolefin film from the other layers, thereby further improving recyclability.

[0057] The deinking layer preferably contains a resin having carboxyl groups, sulfo groups, phosphate groups and / or hydroxyl groups, aluminum, aluminum oxide and / or silicon oxide, as these are soluble in alkaline aqueous solutions. Two or more of these may be included. Among these, resins having hydroxyl groups, aluminum, aluminum oxide and silicon oxide are even more preferred from the viewpoint of imparting oxygen and water vapor barrier properties to the laminated film.

[0058] Carboxylate groups, sulfo groups, and phosphate groups are acidic groups, and resins containing these groups are soluble in alkaline aqueous solutions. Resins containing hydroxyl groups are water-soluble, and are soluble in alkaline aqueous solutions. Examples of main chain structures of resins containing carboxylate groups, sulfo groups, phosphate groups, and / or hydroxyl groups include acrylic resins, styrene-acrylic resins, styrene-maleic acid resins, rosin-modified maleic acid resins, rosin-modified acrylic resins, epoxy resins, polyester resins, polyurethane resins, and phenolic resins.

[0059] Among these resins, resins having hydroxyl groups are preferred from the viewpoint of improving gas barrier properties such as oxygen, and examples include vinyl alcohol-based resins and polysaccharides such as methylcellulose. Examples of vinyl alcohol-based resins include polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and modified polyvinyl alcohol. Two or more of these may be included.

[0060] Furthermore, aluminum, aluminum oxide, and silicon oxide are more preferred from the viewpoint of having gas barrier properties and transparency, which allows the contents to be visually inspected when used as packaging materials.

[0061] Furthermore, polycondensates of a resin having hydroxyl groups and silicon dioxide are preferred because they offer improved oxygen and water vapor gas barrier properties. Such polycondensates are obtained by mixing a hydrolysate of an alkoxysilane represented by Si(OR)4 or SiR'(OR)3 with a resin having hydroxyl groups and then performing dehydration condensation. Here, R represents an alkyl group, and the alkyl group preferably has 1 to 4 carbon atoms. From the viewpoint of reactivity and stability, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane are preferred as alkoxysilanes represented by Si(OR)4. R' represents any monovalent functional group other than an alkoxy group, such as an alkyl group, phenyl group, epoxy group, (meth)acryloyl group, amino group, vinyl group, carbonyl group, etc. Among these, (meth)acryloyl group is particularly preferred from the viewpoint of improving adhesion to varnish layers and ink layers composed of active energy ray curable varnishes and active energy ray curable inks. Two or more alkoxysilanes represented by Si(OR)4 or SiR'(OR)3 may be used. These alkoxysilanes may be hydrolyzed or polycondensed to form a network.

[0062] From the viewpoint of increasing solubility in alkaline aqueous solutions, the thickness of the deinking layer is preferably 3 μm or less, and more preferably 2 μm or less. When aluminum, aluminum oxide and / or silicon oxide are included, from the viewpoint of improving barrier properties, the thickness of the deinking layer is preferably 5 nm or more, and more preferably 10 nm or more. On the other hand, from the viewpoint of suppressing the thermal load on the unstretched polyolefin film during vapor deposition, the thickness of the deinking layer is preferably 500 nm or less, and more preferably 100 nm or less.

[0063] (Laminated film) The thickness of the laminated film of the present invention is preferably 20 μm or more, and more preferably 40 μm or more, from the viewpoint of providing stiffness as a packaging material. On the other hand, from the viewpoint of reducing the amount of plastic used and further reducing the environmental burden, the thickness of the laminated film is preferably 55 μm or less. In conventional structures known as laminates a highly rigid base film and a highly flexible heat-sealable film with an adhesive layer in between, the thickness of the adhesive layer is added to the thickness of each film, making it practically difficult to make the thickness of the laminated film 55 μm or less. In the present invention, by using a single film in which an unoriented polyolefin film is given the properties of both a base material and a sealant, the thickness of the laminated film can be made 55 μm or less.

[0064] Here, the thickness of the laminated film and each layer can be measured using, for example, a Nikon contact-type film thickness gauge (model number MH-15M).

[0065] From the viewpoint of further suppressing tearing as a packaging material, the laminated film of the present invention preferably has a tensile elongation at break of 50% or more in both the MD direction and the TD direction, as specified in JIS K 7127:1999.

[0066] From the viewpoint of increasing the rigidity as a packaging material, the laminated film of the present invention preferably has a tensile modulus of 400 MPa or more in both the MD direction and the TD direction, as specified in JIS K 7127:1999, and more preferably 700 MPa or more.

[0067] Here, the tensile elongation at break and tensile modulus of the laminated film can be measured by the method specified in JIS K 7127:1999. More specifically, plate-shaped test specimens of 15 mm in width and 100 mm in length or more are taken from the MD direction and TD direction of the laminated film, and a tensile test is performed using a tensile testing machine at a tensile speed of 300 mm / min. The elongation and modulus of elasticity are measured when the plate-shaped test specimen breaks. Each measurement is performed three times, and the average value is taken as the tensile elongation at break and tensile modulus of elasticity of the laminated film.

[0068] Here, the MD direction and TD direction in this invention refer to directions perpendicular to the flow direction of the laminated film, and may or may not coincide with the MD direction and TD direction of the unoriented polyolefin film.

[0069] Means for adjusting the tensile elongation at break and tensile modulus of the laminated film to the above range include, for example, irradiating an unoriented polyolefin film with high tensile elongation at break and a tensile modulus of 1,000 MPa or less with an electron beam to promote a crosslinking reaction inside the film, and providing the aforementioned high-rigidity varnish layer.

[0070] The laminated film of the present invention preferably has high rigidity as a packaging material. An indicator of rigidity is, for example, the loop stiffness value. The loop stiffness value of the laminated film of the present invention is preferably 100 mN / 15 mm or more, and more preferably 150 mN / 15 mm or more.

[0071] Here, the loop stiffness value of the laminated film can be measured using a loop stiffness tester. More specifically, a plate-shaped test piece measuring 15 mm in width and 100 mm in length is taken from the laminated film, and the loop stiffness value is measured using a loop stiffness tester DA (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at an indentation speed of 200 mm / min. Each measurement is performed three times, and the average value is calculated.

[0072] Means for adjusting the loop stiffness value to the above range include, for example, increasing the thickness of the unoriented polyolefin film, or irradiating the unoriented polyolefin film with an electron beam to promote the crosslinking reaction inside the film.

[0073] The packaging material of the present invention preferably has excellent tear resistance, making it difficult to tear due to external impacts and protecting the contents.

[0074] (Method of manufacturing laminated film) Next, the method for manufacturing the laminated film of the present invention will be explained with an example.

[0075] The laminated film of the present invention can be obtained, for example, by a method comprising the steps of forming a deinking layer on an unoriented polyolefin film as needed, transferring an active energy ray-curable ink and an active energy ray-curable varnish in that order, and irradiating with an electron beam, or by a method comprising the steps of forming a deinking layer on an unoriented polyolefin film as needed, transferring an active energy ray-curable ink, irradiating with an electron beam, transferring an active energy ray-curable varnish, and irradiating with an electron beam. The former manufacturing method is preferable because the crosslinking reaction of the unoriented polyethylene film proceeds simultaneously with the curing of the varnish layer and the ink layer. In either method, radicals are generated in the unoriented polyethylene film by electron beam irradiation, and the crosslinking reaction proceeds within the unoriented polyethylene film, resulting in a low tensile elongation at break and a high tensile modulus of elasticity of the unoriented polyethylene film. Therefore, the rigidity of the laminated film can be increased. Consequently, there is no need to laminate the unoriented polyethylene film acting as a sealant with a separate base film, and no adhesive layer is required for that purpose, thus a laminated film with excellent recyclability can be obtained.

[0076] Methods for forming a deinking layer include, for example, dissolving the resin in a medium such as water or an organic solvent, coating it onto an unstretched polyolefin film, and drying it, when the resin contains carboxyl groups, sulfo groups, phosphate groups, and / or hydroxyl groups. When the resin contains a polycondensate of a resin containing hydroxyl groups and silicon dioxide, the hydrolysis and / or polycondensation of the alkoxysilane is preferably carried out in the presence of water, a catalyst, and an organic solvent.

[0077] When aluminum, aluminum oxide, and / or silicon oxide are included, methods such as vacuum deposition, sputtering, ion plating, and plasma vapor deposition can be used. Vacuum deposition is particularly preferred because it allows for high-speed film formation with good productivity, and examples of deposition methods include electron beam deposition, resistance heating, and induction heating. Specific deposition methods include, for example, a method of deposition using a compound of the desired composition as a raw material, or, in the case of inorganic compounds such as aluminum oxide and silicon oxide, a method of using aluminum or silicon as a raw material and introducing an oxygen-containing gas into the evaporated aluminum or silicon vapor.

[0078] Examples of methods for transferring active energy ray-curable inks include various printing methods such as offset, gravure, flexographic, inkjet, and screen printing.

[0079] Methods for transferring active energy ray-curable varnishes include various coating methods such as flexographic printing, roller coating, die coating, and bar coating.

[0080] In the electron beam irradiation process, the electron beam acceleration voltage is preferably 90kV or higher, and more preferably 100kV or higher, from the viewpoint of sufficiently advancing the crosslinking reaction, further advancing the curing of the active energy ray-curable varnish and / or active energy ray-curable ink, and further increasing the tensile modulus of the unoriented polyolefin film. On the other hand, the acceleration voltage is preferably 130kV or lower, and more preferably 120kV or lower, from the viewpoint of reducing power consumption. Furthermore, the electron beam irradiation dose is preferably 15kGy or higher, and more preferably 30kGy or higher, from the viewpoint of further advancing the curing of the active energy ray-curable varnish and / or active energy ray-curable ink, further increasing the tensile modulus of the unoriented polyolefin film, and moderately suppressing the tensile elongation at break. On the other hand, the electron beam irradiation dose is preferably 90kGy or lower, and more preferably 75kGy or lower, from the viewpoint of suppressing the decomposition reaction due to excessive radical generation in the unoriented polyethylene film and the resulting weakening, and further suppressing the tearing of the packaging material.

[0081] In the electron beam irradiation process, it is preferable to set the tensile modulus Ga of the laminated film, as specified in JIS K 7127:1999, to 1.3 to 3.3 times the tensile modulus Gb of the unoriented polyolefin film before electron beam irradiation. By setting Ga to 1.3 times or more Gb, the rigidity of the laminated film and packaging material can be increased. On the other hand, by setting Ga to 3.3 times or less Gb, tearing can be further suppressed. It is preferable to adjust the electron beam irradiation conditions so that the ratio of tensile moduli (Ga / Gb) falls within this range.

[0082] (packaging material) The laminated film of the present invention can be suitably used as a packaging material.

[0083] The packaging material preferably has sufficient rigidity to prevent it from collapsing under its own weight. An indicator of the rigidity of the packaging material is, for example, the loop stiffness value. The loop stiffness value of the packaging material of the present invention is preferably 100 mN / 15 mm or more, and more preferably 150 mN / 15 mm or more.

[0084] Here, the loop stiffness value of the packaging material can be measured in the same way as the loop stiffness value of the laminated film.

[0085] Means for adjusting the loop stiffness value to the above range include, for example, increasing the thickness of the unoriented polyolefin film, or using a laminated film obtained by the aforementioned preferred manufacturing method which includes a step of irradiating the unoriented polyolefin film with an electron beam. By irradiating the unoriented polyolefin film with an electron beam, sufficient stiffness for use as a packaging material can be imparted.

[0086] The packaging material of the present invention preferably has excellent tear resistance, making it difficult to tear due to external impacts and protecting the contents.

[0087] (Manufacturing method for packaging materials) The packaging material can be obtained, for example, in the case of a bag-shaped packaging material, by folding the laminated film of the present invention in half so that the varnish layer is on the outside and the unstretched polyolefin film is on the inside (contents side), overlapping the layers, and then heat-sealing the edges of the overlapped layers; or by overlapping two laminated films of the present invention so that the unstretched polyolefin films face each other, and then heat-sealing the edges. Depending on the heat-sealing method, such as side seals, two-sided seals, three-sided seals, four-sided seals, pillow seals, pleated seals, flat-bottom seals, square-bottom seals, gusseted types, etc., various shapes of packaging materials can be obtained, and for example, self-standing packaging materials (standing pouches) can also be obtained.

[0088] Examples of heat sealing methods include heat sealing, bar sealing, impulse sealing, belt sealing, rotary roll sealing, high-frequency sealing, and ultrasonic sealing.

[0089] (Deinking method) The deinking method of the present invention involves immersing a laminated film or packaging material having a deinking layer in an alkaline aqueous solution with a pH of 11 or higher, dissolving the deinking layer with the alkaline aqueous solution, and removing the varnish layer and ink layer from the unstretched polyolefin film.

[0090] Prior to deinking, it is preferable to cut or crush the laminated film or packaging material to make it easier for the deinked layer to come into contact with the alkaline aqueous solution.

[0091] The alkaline aqueous solution has a pH of 11 or higher, preferably 12 or higher, from the viewpoint of improving the solubility of the deinking layer. The alkaline aqueous solution preferably contains a nonionic surfactant along with the alkaline compound. The inclusion of a nonionic surfactant wets the deinking layer and promotes its dissolution, and also removes impurities adhering to the unstretched polyolefin film after dissolution, making it easier to separate the ink layer and varnish layer.

[0092] Examples of alkali compounds include sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, barium hydroxide, and sodium carbonate. Two or more of these may be used.

[0093] Examples of nonionic surfactants include DI-7020, DI-7250, and the "Magic Clean®" series manufactured by Kao Corporation, DIA-Z manufactured by Nisshin Chemical Co., Ltd., and the "Liptol®" series manufactured by Lion Specialty Chemicals Co., Ltd. Two or more of these may be used.

[0094] It is preferable to stir the alkaline aqueous solution in which the laminated film or packaging material is immersed. Examples of stirring means include general dispersers, radial flow turbine blades, paddle blades, propeller blades, anchor blades, and high-shear mixers.

[0095] The unstretched polyolefin film separated by dissolving the deinking layer, along with the varnish layer and ink layer, are preferably separated and recovered by differences in size or specific gravity.

[0096] The separated and recovered unstretched polyolefin film is preferably washed with water and dried. It is then preferably processed into pellets using an extruder or the like, allowing for easy reuse as recycled resin. [Examples]

[0097] The present invention will be described in more detail below with reference to examples. Examples 1-4, 6-10, and 12-26 should be interpreted as Reference Examples 1-24. However, the present invention shall not be construed as being limited to these embodiments.

[0098] First, the measurement and evaluation methods in each example and comparative example will be described.

[0099] (1) Tensile elongation at break and tensile modulus The tensile elongation at break and tensile modulus were measured for the films used in each example and comparative example, and for the laminated films obtained in each example and comparative example, according to the method specified in JIS K 7127:1999. Specifically, three plate-shaped test pieces, each with a width of 15 mm and a length of 100 mm or more, were taken from the MD direction and TD direction of each laminated film. Tensile tests were performed using a Tensilon universal tester (RTG-1210, manufactured by Orientec Co., Ltd.) under the conditions of a chuck distance of 50 mm and a tensile speed of 300 mm / min, and the elongation and tensile modulus were measured when the plate-shaped test pieces broke. Each measurement was performed three times, and the average values ​​were taken as the tensile elongation at break and tensile modulus.

[0100] (2) Heat sealability For each example and comparative example, the laminated films obtained were overlapped with the unoriented polyolefin film sides facing each other, and a 9.5 mm wide heat seal was performed using a heat sealer (TP-701-B, manufactured by Tester Industries Co., Ltd.). For heat sealing conditions, when using unoriented polyethylene film, the temperature range for heat sealing was calculated by increasing the temperature of the upper bar by 5°C increments, starting from 105°C for the upper bar and 80°C for the lower bar, with a pressure of 0.1 Pa and a time of 1 second. When using unoriented polypropylene film, the temperature range for heat sealing was calculated by increasing the temperature of the upper bar by 5°C increments, starting from 140°C for the upper bar and 80°C for the lower bar, with a pressure of 0.1 Pa and a time of 1 second. Heat sealing was deemed possible when no film fusion material adhered to the bars after heat sealing, no wrinkles were observed in the heat-sealed area, and the heat seal strength, measured by the method described below, was 10 N / 15 mm or higher. Heat seal strength measurement method: A 15 mm wide plate-shaped test piece was taken from the heat-sealed area, and a tensile test was performed using a Tensilon universal tester (RTG-1210, manufactured by Orientec Co., Ltd.) at a tensile speed of 300 mm / min to measure the tensile strength. The average value of three measurements was calculated. If the heat-sealable temperature range is 40°C or higher, the heat sealability is considered very good; if it is between 20°C and 40°C, the heat sealability is considered better; if it is between 10°C and 20°C, the heat sealability is considered good; and if it is below 10°C, the heat sealability is considered poor.

[0101] (3) The stiffness of the laminated film (loop stiffness value) For each example and comparative example, plate-shaped test pieces measuring 15 mm in width and 100 mm in length were taken from the laminated films obtained in the MD direction and the TD direction, respectively. Loop stiffness values ​​were measured using a Loop Stiffness Tester DA (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at an indentation speed of 200 mm / min. Measurements were performed three times for each direction, and the average values ​​for the MD and TD directions were calculated. The stiffness was evaluated based on the lower value.

[0102] If the loop stiffness value is 150mN / 15mm or higher, it is considered to have sufficient rigidity as a packaging material and is considered very good. If it is between 100mN / 15mm and 150mN / 15mm, it is considered to have sufficient rigidity and is considered good as a packaging material.

[0103] (4) Resistance to bag breakage For each example and comparative example, two laminated films were bonded together, three sides were heat-sealed, 80% of the film's volume was filled with water, and the remaining sides were heat-sealed to prepare a sample. The sample was dropped from a height of 1 meter, and the number of times it took for the bag to burst was measured. The average value measured for five bags was calculated, and the bag-breaking resistance, an indicator of how easily the bag tears, was evaluated.

[0104] If the bag burst five or more times, the bag-bursting resistance was considered very good; if it burst two or more times but less than five times, the bag-bursting resistance was considered good; and if it burst less than two times, it was considered poor. Note that for laminated films that did not have a heat-sealable temperature range, bag-bursting resistance was not evaluated.

[0105] (5) Deinking property The laminated films obtained in each example and comparative example were cut to 50 mm x 50 mm and added to an aqueous solution (pH=13.6) containing 2.0% by mass potassium hydroxide and 1.0% by mass deinking agent (DI-7020, manufactured by Kao Corporation), and stirred under the following two conditions. <Condition 1> Temperature: 50℃, Rotation speed: 200rpm, Time: 20 minutes <Condition 2> Temperature: 80℃, Rotation speed: 200rpm, Time: 60 minutes.

[0106] Subsequently, the laminated film was removed, washed with a small amount of water, and then visually inspected for any remaining ink layer. The deinking properties were then evaluated according to the following criteria. A: Under Condition 1, no ink layer is observed in the laminated film. B: Under Condition 1, an ink layer remained on the laminated film, but under Condition 2, no ink layer was observed on the laminated film. C: In both <Condition 1> and <Condition 2>, an ink layer is observed on the laminated film.

[0107] (6) Thermal conductivity of the varnish layer Since the curing conditions of the varnish layer do not affect the thermal conductivity as long as it is sufficiently cured, the thermal conductivity of the cured film obtained by curing the varnish used in each example and comparative example was measured as an indicator of the thermal conductivity of the varnish layer in each example and comparative example. The varnish was evenly placed in an aluminum petri dish so that the sample height was approximately 0.2 mm. Varnish 2 was heated in an oven at 100°C for 3 hours, and the other varnishes were irradiated with an electron beam using an electron beam irradiation device (EC250 / 30 / 90LS manufactured by Iwasaki Electric Co., Ltd.) under the conditions of an acceleration voltage of 250 kV and an irradiation dose of 300 kGy, to produce cured films of approximately 0.2 mm thickness each. The thermal conductivity of the obtained cured films was measured using a thermal conductivity meter (HC-074 / 600 manufactured by Eiko Seiki Co., Ltd.) in accordance with JIS A 1412-2:1999 by the heat flow meter method.

[0108] (7) Evaluation of particle dispersion state in varnish The particle size distribution in varnish containing inorganic particles was evaluated using a dynamic light scattering device (SZ-100V2, Horiba, Ltd.) with a measurement range of 0.3 nm to 10 μm. The presence or absence of aggregates was determined by whether the particle size distribution was unimodal or multimodal. If aggregates were present, there was one or more secondary particle size peaks in addition to the primary particle size peaks.

[0109] Next, the materials used in each example and comparative example will be described.

[0110] [Unstretched polyolefin film] Film 1: Unoriented polypropylene film with a thickness of 25 μm (P1171 manufactured by Toyobo Co., Ltd.), tensile elongation at break: MD direction: 330%, TD direction: 420%, tensile modulus: MD direction: 590 MPa, TD direction: 590 MPa, no deinking layer. Film 2: Unoriented polypropylene film with a thickness of 50 μm (P1146 manufactured by Toyobo Co., Ltd.), tensile elongation at break: MD direction: 530%, TD direction: 560%, tensile modulus: MD direction: 400 MPa, TD direction: 370 MPa, no deinking layer. Film 3: Unoriented polypropylene film with a thickness of 30 μm (P1128 manufactured by Toyobo Co., Ltd.), tensile elongation at break: MD direction: 400%, TD direction: 500%, tensile modulus: MD direction: 440 MPa, TD direction: 480 MPa, no deinking layer. Film 4: 50 μm thick unoriented polypropylene film (ZK-207, manufactured by Toray Film Processing Co., Ltd.), tensile elongation at break: MD direction: 700%, TD direction: 810%, tensile modulus: MD direction: 490 MPa, TD direction: 450 MPa, no deinking layer. Film 5: 30 μm thick aluminum-deposited unoriented polypropylene film (VM-CPP2703, manufactured by Toray Film Processing Co., Ltd.), tensile elongation at break: MD direction: 350%, TD direction: 330%, tensile modulus: MD direction: 800 MPa, TD direction: 770 MPa, deinking layer: aluminum-deposited layer. Film 6: Unoriented polypropylene film with a thickness of 20 μm (P1128 manufactured by Toyobo Co., Ltd.), tensile elongation at break: MD direction: 350%, TD direction: 500%, tensile modulus: MD direction: 490 MPa, TD direction: 500 MPa, no deinking layer. Film 7: Unoriented polypropylene film with a thickness of 50 μm (P1128 manufactured by Toyobo Co., Ltd.), tensile elongation at break: MD direction: 440%, TD direction: 500%, tensile modulus: MD direction: 430 MPa, TD direction: 450 MPa, no deinking layer. Film 8: Unoriented polypropylene film with a thickness of 60 μm (P1128 manufactured by Toyobo Co., Ltd.), tensile elongation at break: MD direction: 460%, TD direction: 500%, tensile modulus: MD direction: 430 MPa, TD direction: 450 MPa, no deinking layer. Film 9: 50 μm thick unoriented polyethylene film (Tamapoly Co., Ltd. SE620L), tensile elongation at break MD direction: 600%, TD direction: 750%, tensile modulus of elasticity MD direction: 260 MPa, TD direction: 310 MPa, no deinking layer. Film 10: Unoriented polyethylene film with a thickness of 40 μm (TUX-HC manufactured by RM Tosero Co., Ltd.), tensile elongation at break: MD direction: 630%, TD direction: 700%, tensile modulus: MD direction: 340 MPa, TD direction: 340 MPa, no deinking layer. Film 11: 30 μm thick silicon oxide vapor-deposited unoriented polyethylene film (TOPPAN Co., Ltd. GL-LE-G), tensile elongation at break MD direction: 530%, TD direction: 520%, tensile modulus MD direction: 420 MPa, TD direction: 440 MPa, deinking layer: silicon oxide vapor-deposited layer. Film 12: 50 μm thick unoriented polyethylene film (Tamapoly Co., Ltd. UB-3), tensile elongation at break MD direction: 690%, TD direction: 600%, tensile modulus MD direction: 520 MPa, TD direction: 720 MPa, no deinking layer. Film 13: Biaxially oriented polypropylene film with a thickness of 30 μm (Futamura Chemical Co., Ltd. FOR), tensile elongation at break: MD direction: 185%, TD direction: 35%, tensile modulus: MD direction: 1,800 MPa, TD direction: 3,200 MPa, no deinking layer. Film 14: 30 μm thick corona-treated biaxially oriented polypropylene film (FOH, manufactured by Futamura Chemical Co., Ltd.), with a heat-sealed layer on the side opposite the corona-treated side (printed side). Tensile elongation at break: MD direction: 175%, TD direction: 30%. Tensile modulus: MD direction: 1,800 MPa, TD direction: 3,300 MPa. No deinking layer.

[0111] [varnish] Varnish 1: EB-curing varnish PROCURE EB GLOSS COATING C2 (manufactured by Sakata Inx Co., Ltd.), the cured varnish layer contains acrylic resin. Varnish 2: Water-based varnish "TerraWet (registered trademark)" Gloss Coating G9 / 374 (manufactured by Actega). The varnish layer after drying contains polyurethane resin. This mixture consists of a 3:1 ratio of varnish to varnish, with 0.1% by mass of "Aeroxide (registered trademark)" AluC (alumina particles, manufactured by Evonik) added. No aggregates were found in the particle size distribution measurement. This mixture consists of a 4:1 ratio of varnish to varnish, with 0.5% by mass of "Aeroxide (registered trademark)" AluC (alumina particles, manufactured by Evonik) added. No aggregates were found in the particle size distribution measurement. This mixture consists of a 5:1 ratio of varnish to varnish, with 1.0% by mass of "Aeroxide (registered trademark)" AluC (alumina particles, manufactured by Evonik) added. No aggregates were found in the particle size distribution measurement. This mixture consists of a 6:1 ratio of varnish to varnish, with 2.5% by mass of "Aeroxide (registered trademark)" AluC (alumina particles, manufactured by Evonik) added. No aggregates were found in the particle size distribution measurement. This mixture consists of a 7:1 ratio of varnish to varnish, with 1.0% by mass of "Aerosil (registered trademark)" 200 (silica particles, manufactured by Evonik) added. Agglomeration was observed during particle size distribution analysis. This mixture consists of a 8:1 ratio of varnish to varnish, with 1.0% by mass of "Admanano (registered trademark)" YA010C-SP3 (silica particles, manufactured by Admatec Co., Ltd.) added. No aggregates were found in the particle size distribution measurement. This mixture consists of a 9:1 ratio of varnish to varnish, with 1.0% by mass of "Typeque®" PFR404 (titanium dioxide particles, manufactured by Ishihara Sangyo Co., Ltd.) added. No aggregates were found in the particle size distribution measurement.

[0112] [Ink] Ink 1: EB-curing flexographic ink GEL-FLEX EB Cyan NA (manufactured by Sakata Inx Co., Ltd.), the ink layer after curing contains acrylic resin. Ink 2: Solvent flexographic ink "Brightflex®" cyan (manufactured by DIC Corporation). The ink layer after drying does not contain acrylic resin.

[0113] (Example 1) For film 1, ink 1 was applied at a rate of 3.5 ml / m² using a desktop color mixer Amsterdam 6 (manufactured by IGT). 2 , Varnish 1 8.5 ml / m 2 Solid printing was performed using anilox of a certain capacity. Next, electron beam irradiation was performed using an electron beam irradiation device (EC250 / 30 / 90LS manufactured by Iwasaki Electric Co., Ltd.) under the conditions of an acceleration voltage of 110kV and irradiation dose of 30kGy to produce a laminated film having areas where the varnish layer / ink layer / film 1 are in contact in this order. The obtained laminated film has excellent recyclability because it does not have an adhesive layer made of different materials. The results of physical property measurements and various evaluations of the laminated film performed using the above method are shown in Table 1.

[0114] (Examples 2-12, Comparative Examples 1-2) A laminated film was prepared using the same procedure as in Example 1, except that film 1 was replaced with films 2-14. The resulting laminated film does not have an adhesive layer made of different materials, and therefore has excellent recyclability. The results of evaluation using the method described above are shown in Tables 1-2.

[0115] (Comparative Examples 3-4) Laminated films were prepared using the same procedure as in Examples 3 and 10, except that varnish 1 was not used. The resulting laminated films do not have adhesive layers made of different materials, and therefore have excellent recyclability. The results of evaluation using the method described above are shown in Table 2.

[0116] (Comparative Example 5) For film 13, ink 1 was applied at a rate of 3.5 ml / m² using a desktop color mixing device Amsterdam 6 (manufactured by IGT). 2Solid printing was performed using anilox of the specified capacity. Next, electron beam irradiation was performed using an electron beam irradiation device (EC250 / 30 / 90LS manufactured by Iwasaki Electric Co., Ltd.) under the conditions of an acceleration voltage of 110kV and irradiation dose of 30kGy. Subsequently, dry mixed laminate adhesive ("Takelac" (registered trademark) A953 / "Takenate" (registered trademark) A93 manufactured by Mitsui Chemicals, Inc.) was applied to a dry film thickness of 2.0g / m². 2 The printed surface was coated in this manner, dried in an oven at 80°C for 1 minute, then film 4 was laminated to it, and cured at 40°C for 72 hours to produce a laminated film. The resulting laminated film has an adhesive layer made of different materials, so its recyclability is insufficient. The results of the evaluation using the method described above are shown in Table 2.

[0117] (Example 13) For film 3, ink 1 was applied at a rate of 3.5 ml / m² using the Amsterdam 6 desktop color mixer (manufactured by IGT). 2 Solid printing was performed using anilox of the specified volume. Next, electron beam irradiation was performed using an electron beam irradiation device (EC250 / 30 / 90LS manufactured by Iwasaki Electric Co., Ltd.) under the conditions of an acceleration voltage of 110kV and irradiation dose of 30kGy. Furthermore, varnish 2 was applied at a rate of 8.5ml / m² using a desktop coloring device Amsterdam6 (manufactured by IGT). 2 A solid print was made using anilox of a certain capacity, and the film was heat-dried at 80°C for 1 minute to produce a laminated film. The resulting laminated film does not have an adhesive layer made of different materials, and therefore has excellent recyclability. The results of the evaluation using the method described above are shown in Table 3.

[0118] (Example 14) For film 3, ink 2 was applied at a rate of 3.5 ml / m² using a desktop color mixer Amsterdam 6 (manufactured by IGT). 2 The print was solid-colored using anilox in a certain volume and heat-dried at 80°C for 1 minute. Next, varnish 1 was applied at a rate of 8.5 ml / m² using a desktop color mixer Amsterdam 6 (manufactured by IGT). 2Offset printing was performed using an anilox roll with a capacity of

[0119] (Example 15) For Film 3, using a desktop color development device Amsterdam6 (manufactured by IGT), Ink 2 was offset printed at 3.5 ml / m 2 using an anilox roll with a capacity of and heat dried at 80°C for 1 minute. Furthermore, using a desktop color development device Amsterdam6 (manufactured by IGT), Varnish 2 was offset printed at 8.5 ml / m 2 using an anilox roll with a capacity of and heat dried at 80°C for 1 minute to produce a laminated film. Since the obtained laminated film has no adhesive layer made of different materials, it has excellent recyclability. The results evaluated by the above method are shown in Table 3.

[0120] (Examples 16 - 21) A laminated film was produced in the same procedure as in Example 3 except that the capacity of the anilox roll used for color development of Varnish 1 was changed and the varnish layer thickness was changed as described in Table 3. Since the obtained laminated film has no adhesive layer made of different materials, it has excellent recyclability. The results evaluated by the above method are shown in Table 3.

[0121] (Examples 22 - 26) A laminated film was produced in the same procedure as in Example 1 except that the acceleration voltage or irradiation dose of the electron beam was changed as described in Table 4. Since the obtained laminated film has no adhesive layer made of different materials, it has excellent recyclability. The results evaluated by the above method are shown in Table 4.

[0122] (Examples 27 - 33) Laminated films were prepared using the same procedure as in Example 5, except that the type of varnish was changed as shown in Table 5. The thickness of the varnish layer varied depending on the viscosity of the varnish, as shown in Table 4. The resulting laminated films do not have adhesive layers made of different materials, and therefore have excellent recyclability. The results of evaluation using the method described above are shown in Table 5.

[0123] (Examples 34-35) A laminated film was prepared using the same procedure as in Example 28, except that the amount of anilox used during the coloring of varnish 4 was changed to alter the varnish layer thickness as shown in Table 5. The resulting laminated film does not have an adhesive layer made of different materials and therefore has excellent recyclability. The results of the evaluation using the method described above are shown in Table 5.

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3]

[0127] [Table 4]

[0128] [Table 5]

Claims

1. A laminated film having a portion in which a varnish layer containing an acrylic resin, a polyurethane resin, a polyester resin, and / or an epoxy resin, an ink layer, a deinking layer, and an unstretched polyolefin film are in contact in this order, wherein the deinking layer is made of aluminum, aluminum oxide, and / or silicon oxide, and the laminated film consists only of the varnish layer, the ink layer, the deinking layer, and the unstretched polyolefin film, wherein the varnish layer contains an acrylic resin in which a polyfunctional (meth)acrylate is crosslinked.

2. The laminated film according to claim 1, wherein the thickness is 20 μm or more and 55 μm or less.

3. The laminated film according to claim 1 or 2, wherein the tensile elongation at break, as defined in JIS K 7127:1999, is 50% or more in both the MD direction and the TD direction.

4. The laminated film according to claim 1 or 2, wherein the tensile modulus of elasticity, as defined in JIS K 7127:1999, is 400 MPa or more in both the MD direction and the TD direction.

5. The laminated film according to claim 1 or 2, wherein the tensile modulus of elasticity, as defined in JIS K 7127:1999, is 700 MPa or more in both the MD direction and the TD direction.

6. The laminated film according to claim 1 or 2, wherein the thermal conductivity of the varnish layer is 0.15 W / m·K or more and 0.23 W / m·K or less.

7. The laminated film according to claim 1 or 2, wherein the thickness of the varnish layer is greater than 5.0 μm and 10.0 μm or less.

8. The laminated film according to claim 1 or 2, wherein the ink layer contains an acrylic resin.

9. A method for producing a laminated film according to claim 1 or 2, comprising the steps of transferring an active energy ray-curable ink and an active energy ray-curable varnish to an unoriented polyolefin film in that order, and irradiating it with an electron beam.

10. The method for manufacturing a laminated film according to claim 9, wherein the acceleration voltage of the electron beam in the step of irradiating with the electron beam is 90 kV or more and 130 kV or less, and the irradiation intensity is 15 kGy or more and 90 kGy or less.

11. The method for manufacturing a laminated film according to claim 9, wherein, in the step of irradiating with an electron beam, the electron beam irradiation makes the tensile modulus of the laminated film, as defined in JIS K 7127:1999, 1.3 to 3.3 times that of the unoriented polyolefin film before electron beam irradiation.

12. A packaging material having a portion in which a varnish layer, an ink layer, a deinking layer, and an unstretched polyolefin film are in contact in this order, wherein the deinking layer is made of aluminum, aluminum oxide, and / or silicon oxide, and the material consists only of the varnish layer, ink layer, deinking layer, and unstretched polyolefin film, wherein the varnish layer is made of an acrylic resin crosslinked with polyfunctional (meth)acrylate.

13. A method for deinking a laminated film according to claim 1 or 2, comprising immersing it in an alkaline aqueous solution with a pH of 11 or higher, dissolving the deinking layer in the alkaline aqueous solution, and removing the varnish layer and the ink layer from the unstretched polyolefin film.

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