Laminated film

Abstract

This invention provides a laminated film that has suitable lamination strength for use as a packaging film, and in which the base layer and sealant layer can be easily separated by immersion in water. [Solution] A laminated film having an anchor coat layer and a resin layer on at least one surface of a base film, wherein the resin layer contains an inorganic compound and a water-soluble resin, and the mass ratio of the inorganic compound to the water-soluble resin (inorganic compound / water-soluble resin) is 3 / 97 to 45 / 55.

Description

Technical Field

[0001] The present invention relates to a laminated film and a method for separating and recovering the same.

Background Art

[0002] In recent years, due to the increasing environmental awareness, the demand for recyclable packaging films has been increasing. For example, by using a polyolefin resin film for the base material layer and the sealant layer, a single-material packaging film with high recyclability, in which the entire film is composed of a single material, has attracted attention. However, in order to obtain such a single-material packaging film with high recyclability, the selectivity of the base material film is low, and the mechanical strength may be insufficient for packaging applications.

[0003] On the other hand, in the case of a packaging film composed of different resin layers, there is a method of using a coating agent for deinking and a laminating adhesive for peeling to separate and recover each resin layer and recycle it. However, in this method, since a special layer for separation needs to be provided on the base material, it leads to an increase in the number of processes, contributing to cost increase and environmental burden.

[0004] As a method of separating and recovering a laminated film layer by layer and recycling it without using such a coating agent for deinking and a laminating adhesive for peeling, it has been proposed to provide a resin layer containing polyvinyl alcohol as an ink release layer between the resin film and the printing layer (Patent Document 1). However, the film described in Patent Document 1 may have a problem that the ink release layer reduces the laminating strength of the laminated film, and the practical laminating strength when used as a packaging film may be insufficient.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The present invention provides a laminated film that has suitable lamination strength for use as a packaging film, and that allows for easy separation of the base film and sealant layer by immersion in water after use. [Means for solving the problem]

[0007] As a result of diligent research, the inventors have discovered that a laminated film having an anchor coat layer and a specific resin layer on a base film, wherein the resin layer contains a water-soluble resin and an inorganic compound in a specific ratio, when a sealant layer is bonded to it to form a package, possesses practical lamination strength as a package under normal conditions, while allowing for easy separation of the base film and the sealant layer by immersion in water, thus leading to the present invention. In other words, the gist of the present invention is as follows. (1) A laminated film in which at least a base film / anchor coat layer / resin layer is laminated in this order, A laminated film characterized in that the resin layer contains an inorganic compound and a water-soluble resin, and the mass ratio of the inorganic compound to the water-soluble resin (inorganic compound / water-soluble resin) is 3 / 97 to 45 / 55. (2) The laminated film according to (1), wherein the water-soluble resin contains polyvinyl alcohol and / or an ethylene-vinyl alcohol copolymer. (3) The laminated film according to (1) or (2), wherein the inorganic compound is an inorganic layered compound. (4) The laminated film according to (1) to (3), wherein the base film is a polyamide resin film or a polyester resin film. (5) Oxygen permeability measured under conditions of 20°C and 65% RH is 15 ml / (m³). 2 The laminated films described in (1) to (4) are less than or equal to (day·MPa). (6) A laminated film for packaging using the laminated films described in (1) to (5). (7) A laminate in which a laminate adhesive layer is formed directly on the resin layer surface of the laminated film described in (1) to (6) or via a printed layer. (8) A laminate in which a sealant layer is formed on the laminate of (7). (9) The normal lamination strength is 1.20 N / 15 mm or more, and It is characterized by having a water-applied lamination strength of 0.20 N / 15 mm or less. The laminate described in (7) or (8). A method for separating and recovering laminated films, wherein the laminate described in (10)(7) or (8) is immersed in water at 20 to 50°C to recover the separated films. [Effects of the Invention]

[0008] The laminated film of the present invention, when used as a packaging body with a laminated sealant layer, possesses practical lamination strength as a packaging body, while allowing for easy separation of the base film and sealant layer by immersion in water. Therefore, it can be suitably used as a highly recyclable packaging film. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below.

[0010] The laminated film comprises at least a base film, an anchor coat layer, and a resin layer, laminated in this order, wherein the resin layer contains an inorganic compound and a water-soluble resin in a specific ratio.

[0011] <Base film> The base film of the present invention is not particularly limited, but a film having mechanical strength suitable for packaging applications is preferred. From this viewpoint, polyester resin film or polyamide resin film is particularly preferred. In the present invention, even if a base film made of a different material from the sealant layer is used, it can be easily separated and recycled. <Polyester resin film> Examples of polyester resins constituting the base film include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), poly(1,4-cyclohexylenedimethylene terephthalate), and polylactic acid (PLA), and may contain copolymer components. The polyester resin can be used in the form of one or a mixture of two or more. The raw materials for the polyester resin are not limited, and for example, in addition to conventional petroleum-derived monomers, depolymerized monomers obtained by chemical recycling can also be used.

[0012] The polyester resin film may contain components other than polyester resin, as long as they do not hinder the effects of the present invention. For example, it may contain various additives such as antioxidants, ultraviolet absorbers, preservatives, antistatic agents, antiblocking agents, and inorganic fine particles. The polyester resin film may be an unstretched film, but it is generally preferable that it be uniaxially or biaxially stretched, and more preferably biaxially stretched. Conventional stretching methods such as roll stretching, rolling stretching, belt stretching, tenter stretching, tube stretching, or combinations thereof can be applied. The thickness of the polyester resin film is not limited and can be set appropriately depending on the application, location of use, etc., but it is usually sufficient to keep it within a range of about 3 to 50 μm. The polyester resin film may be given functions such as a matte finish or straight cutability, to the extent that it does not interfere with the effects of the present invention. Conventional methods can be used to impart functions such as a matte finish or straight cutability. <Polyamide resin film> As the polyamide resin constituting the base film, any melt-moldable thermoplastic resin having an amide bond (-CONH-) in its molecule may be used, and known or commercially available ones can be employed. For example, aliphatic polyamides such as polycaprolactam (nylon 6), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyaminoundecamide (nylon 11), poly laurylamide (nylon 12), and semi-aromatic polyamides such as polyhexamethylene terephthalamide (nylon 6T), polynonanediamine terephthalamide (nylon 9T), polydecandiamine terephthalamide (nylon 10T). In addition, copolymers, mixtures, etc. of these polyamide resins can be mentioned. The polyamide resin can be used in the form of one kind or a mixture of two or more kinds. In the present invention, nylon 6, which is excellent in mechanical properties such as impact resistance, is preferable. The above raw materials are not limited. For example, in addition to conventional petroleum-derived monomers, monomers obtained by depolymerization through chemical recycling can also be used.

[0013] Furthermore, a remelted resin obtained by melting the polyamide resin can be used. In the present invention, from the viewpoints of environmental protection and effective utilization of resources, resin waste materials of polyamide resins (especially nylon 6 resin) can be used as the remelted resin. More specifically, examples include pellets formed by remelting unstretched scraps, ear trimmings, slit scraps, defective products, etc. generated during the production of polyamide films. The content of the polyamide resin in the polyamide resin film is not limited, but can usually be set within the range of about 90 to 100% by mass.

[0014] In the polyamide resin film, components other than the polyamide resin may be contained within a range that does not interfere with the effects of the present invention. For example, it may contain various additives such as antioxidants, ultraviolet absorbers, preservatives, antistatic agents, antiblocking agents, and inorganic fine particles.

[0015] The polyamide resin film may be composed of a single layer, or may be a film composed of a plurality of layers formed by co-melt extrusion, lamination, or the like. In particular, in the present invention, from the viewpoint of simplifying the manufacturing process, a polyamide resin film composed of a single layer is preferred.

[0016] As the polyamide resin film, a ready-made or commercially available polyamide resin film can be used, or a film formed by a known film forming method can also be used.

[0017] When manufacturing the polyamide resin film, for example, after extruding the molten polymer from a T-die, it is cooled with a casting roll to produce an unstretched sheet. Then, this is simultaneously biaxially stretched or sequentially biaxially stretched. The stretched film thus obtained is heat-treated at a temperature around 200 °C for a short time, for example, to improve dimensional stability. In this way, a polyamide resin film can be obtained. That is, the polyamide resin film in the film of the present invention is preferably a biaxially stretched film.

[0018] In addition, the polyamide resin film may be subjected to a surface treatment such as corona discharge treatment, etc., as long as the effects of the present invention are not impaired as necessary.

[0019] The thickness of the polyamide resin film is not limited and can be appropriately set according to the application, etc., but it is usually within the range of about 3 to 50 μm. Functions such as a matte finish and linear cutability may be imparted to the polyamide resin film within a range that does not prevent the effects of the present invention. As a method for imparting functions such as a matte finish and linear cutability, conventional methods can be used.

[0020] <Water-soluble resin> Examples of water-soluble resins in the present invention include resins having hydrogen-bonding groups, such as hydroxyl groups, amino groups, thiol groups, carboxyl groups, sulfonic acid groups, and phosphate groups, as well as resins having ionic groups, such as carboxylate groups, sulfonic acid ion groups, phosphate ion groups, ammonium groups, and phosphonium groups. Examples of water-soluble resins used in the present invention include polyvinyl alcohol, ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), polyacrylonitrile (PAN), polysaccharides, polyacrylic acid and its esters, etc. Two or more of these may be used. Polyvinyl alcohol and / or EVOH are particularly preferred.

[0021] From the viewpoint of water-laminate strength, the degree of saponification of polyvinyl alcohol is preferably 70-99% in mole percentage, more preferably 85-99%, and most preferably 95-99%. The degree of polymerization is preferably 100-5000, and more preferably 200-3000. The viscosity of the polyvinyl alcohol is preferably 1-40 mPa·s, and more preferably 10-30 mPa·s, for a 4% by mass aqueous solution of polyvinyl alcohol at 20°C.

[0022] In the ethylene-vinyl alcohol copolymer (EVOH), the vinyl alcohol fraction is preferably 40 mol% or more, more preferably 40 to 99 mol%, and most preferably 45 to 97 mol%. The EVOH may be modified with a small amount of copolymer monomer, as long as the objective of the present invention is not hindered.

[0023] The water-soluble resin used in the present invention may contain a crosslinking agent.

[0024] Examples of crosslinking agents include titanium-based coupling agents, silane-based coupling agents, melamine-based coupling agents, epoxy-based coupling agents, isocyanate-based coupling agents, copper compounds, and zirconium compounds. Two or more of these may be used. Among these, the use of zirconium compounds is preferred.

[0025] Specific examples of zirconium compounds include zirconium halides such as zirconium oxychloride, zirconium hydroxychloride, zirconium tetrachloride, and zirconium bromide; zirconium salts of mineral acids such as zirconium sulfate, basic zirconium sulfate, and zirconium nitrate; zirconium salts of organic acids such as zirconium formate, zirconium acetate, zirconium propionate, zirconium caprylate, and zirconium stearate; and zirconium complex salts such as ammonium zirconium carbonate, sodium zirconium sulfate, ammonium zirconium acetate, sodium zirconium oxalate, sodium zirconium citrate, and ammonium zirconium citrate.

[0026] <Inorganic compounds> The resin layer of the present invention must contain an inorganic compound from the viewpoint of improving the lamination strength under normal conditions, reducing the lamination strength when wet, and allowing for easy peeling when immersed in water. By containing an inorganic compound in the resin layer, the adhesion between the water-soluble resin and the anchor coat layer is improved under normal conditions, thereby improving the lamination strength under normal conditions. At the same time, water penetrates the resin layer more easily, promoting the dissolution of the resin layer, which reduces the lamination strength when wet and improves separation in water. Examples of inorganic compounds include clay, calcium carbonate, magnesium carbonate, zinc carbonate, wollastonite, silica, alumina, calcium oxide, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, magnesium aluminosilicate, glass balloon, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, sodium silicate, aluminum hydroxide, iron oxide, zirconium oxide, barium sulfate, titanium dioxide, carbon black, kaolinite, dickite, nacrite, halloysite, antigorite, chrysotile, pyrophyllite, montmorillonite, beidelite, bentonite, nontronite, saponite, soconite, stevensite, hectorite, tetrasilyl mica, sodium teniolite, muscovite, margalite, talc, vermiculite, phlogopite, xanthophyllite, chlorite, etc. Two or more of these inorganic compounds may be used. In particular, from the viewpoint of adhesion, it is preferable to use inorganic layered compounds such as kaolinite, dickite, nacrite, halloysite, antigorite, chrysotile, pyrophyllite, montmorillonite, beidelite, bentonite, nontronite, saponite, soaconite, stevensite, hectorite, tetrasilyl mica, sodium teniolite, muscovite, margalite, talc, vermiculite, phlogopite, xanthophyllite, and chlorite. Inorganic layered compounds are inorganic compounds in which unit crystal layers are stacked on top of each other to form a layered structure. The aforementioned "layered structure" refers to a structure in which planes in which atoms are strongly bonded together by covalent bonds or the like and densely arranged are stacked in parallel by weak bonding forces such as van der Waals forces.

[0027] In the present invention, materials obtained by subjecting the inorganic layered compound to treatment such as ion exchange with organic matter to improve dispersibility and other properties can also be used.

[0028] From the viewpoint of adhesion and other factors, the inorganic layered compound preferably has an average particle size of 5 μm or less. Furthermore, when using an inorganic layered compound, the aspect ratio is usually preferably 50 to 5000, and more preferably 200 to 3000. <Resin layer> The mass ratio of inorganic compound to water-soluble resin in the resin layer (inorganic compound / water-soluble resin) must be 3 / 97 to 45 / 55, and preferably 5 / 95 to 35 / 65. If the mass ratio of inorganic compound exceeds 45%, the dispersibility of the inorganic compound in the resin layer deteriorates, which can worsen the adhesion of the resin layer, make it difficult for water to penetrate, and may prevent the laminate from completely separating in water. If the mass ratio of inorganic compound falls below 3%, the adhesion-improving effect of adding the inorganic compound may not be sufficiently apparent, and the normal lamination strength and water-lamination strength may not be satisfied.

[0029] Furthermore, the total proportion of inorganic compounds and water-soluble resin components in the resin layer is not particularly limited, but it is generally desirable to set it within the range of 90 to 100% by mass, and especially 95 to 100% by mass. If the proportion is less than 100%, other components may be included. That is, the water-soluble resin layer may contain various additives, such as ultraviolet absorbers, colorants, and antioxidants, as long as they do not impair the effects of the present invention.

[0030] The thickness of the resin layer is not particularly limited, but from the viewpoint of adhesion with the anchor coat layer, it is preferably 0.1 to 1 μm, more preferably 0.2 to 0.7 μm, and most preferably 0.25 to 0.5 μm.

[0031] <Anchor Coat Layer> In this invention, it is necessary to provide an anchor coat layer between the base film and the resin layer. By providing the anchor coat layer, the adhesion between the base film and the resin layer is improved, and suitable normal lamination strength can be obtained. The components constituting the anchor coat layer are not particularly limited, and components used in known or commercially available anchor coat agents can be used. Examples include various compounds such as isocyanates, polyurethanes, polyesters, polyethyleneimines, polybutadienes, polyolefins, and alkyl titanates.

[0032] Among these, isocyanate-based, polyurethane-based, and polyester-based materials are particularly preferred because they more reliably provide the effects of the present invention. Furthermore, it is preferable to use one or more of the mixtures and / or reaction products of (1) and (2) below. (1) an isocyanate compound, a mixture of one or more polyurethanes and urethane prepolymers, and reaction products (2) A mixture of one or more of the group consisting of polyester, polyol, and polyether, and an isocyanate compound, and the reaction product The thickness of the anchor coat layer is not particularly limited, but it is preferably 0.02 to 0.2 μm dry, and more preferably 0.04 to 0.1 μm.

[0033] <Coating Process> The resin layer is formed by applying a resin-forming coating to the surface of the anchor coat layer and then heat-treating it.

[0034] A coating for forming a resin layer can be prepared by blending a solvent with a water-soluble resin component. The preparation method is not particularly limited. When the inorganic compound is an inorganic layered compound, from the viewpoint of uniformity during blending and ease of handling, examples of methods include: mixing a dispersion of the inorganic layered compound that has been pre-swollen and cleaved with a solution of the water-soluble resin component, and then removing the solvent (Method 1); adding the dispersion of the inorganic layered compound that has been swollen and cleaved with the water-soluble resin component and then removing the solvent (Method 2); adding the inorganic layered compound to a solution of the water-soluble resin component to obtain a dispersion that has been swollen and cleaved, and then removing the solvent (Method 3); and hot kneading the inorganic layered compound and the water-soluble resin component (Method 4). From the viewpoint that a large aspect ratio of the inorganic layered compound can be easily obtained, it is preferable to use the above methods (1) to (3).

[0035] Suitable dispersion media (solvents) for inorganic compounds include water, as well as alcohols such as methanol, ethanol, propanol, isopropanol, ethylene glycol, and diethylene glycol, and organic solvents such as dimethylformamide, dimethyl sulfoxide, acetone, and silicone oil. Among these, water, alcohol, or water-alcohol mixtures are preferred.

[0036] For mixing inorganic compounds and water-soluble resin components, known devices such as homogenizers can be used. From the viewpoint of dispersibility of inorganic compounds, it is preferable to perform high-pressure dispersion treatment using a high-pressure dispersion device.

[0037] From the viewpoint of coating properties, the coating for forming the resin layer is preferably adjusted so that the Zahn cup viscosity (measured with Rigosha Co., Ltd.: Zahn cup viscosity: No. 3) is in the range of 20 to 50 S, and more preferably in the range of 25 to 45 S.

[0038] Furthermore, the solid content concentration of the resin layer-forming coating can be appropriately changed depending on the specifications of the coating equipment, drying equipment, or heating equipment, for example, but from the viewpoint of coatability, it is usually in the range of 2 to 15% by mass, particularly preferably 4 to 8% by mass, and even more preferably 5 to 7% by mass.

[0039] The method for applying the resin layer-forming coating is not particularly limited, and known methods can be used as appropriate. For example, direct gravure, reverse gravure, microgravure, two-roll bead coating, bottom-feed three-roll reverse coating, doctor knife method, die coating, dip coating, bar coating, and other methods combining these can be used.

[0040] After applying the resin-forming coating, the solvent is removed by drying. The drying temperature is not limited, but can usually be set within a range of approximately 30 to 160°C. The drying time can be set appropriately depending on the drying temperature, etc., but generally it should be within a range of 0.5 to 10 minutes. Known drying methods can be employed, such as drying in an oven or using various types of dryers. In this way, the resin layer can be formed.

[0041] Other methods for forming the resin layer include applying a resin layer-forming coating to an unstretched film, removing the solvent by drying at a temperature of 90-120°C, and then performing simultaneous biaxial stretching or sequential biaxial stretching. In other words, the formation and lamination of the resin layer can be suitably carried out by so-called in-line coating.

[0042] Furthermore, after removing the solvent, the material can be further thermally aged at 110-220°C. The aging time is not limited as long as the above temperature range can be maintained, but in the case of methods involving contact with a heat medium, such as a hot air dryer, it can be appropriately set within a range of approximately 1 second to 100 minutes. The heat source is also not particularly limited, and various methods such as heat roll contact, heat medium contact (air, oil, etc.), infrared heating, and microwave heating can be applied.

[0043] <Laminate> The laminated film of the present invention can also be formed by laminating a laminate adhesive layer and a sealant layer in that order onto the resin layer surface. Furthermore, the laminate adhesive layer can be formed on the printed layer. A specific example of the laminate configuration is as follows: Laminated film / Laminate adhesive layer / Sealant layer Laminated film / Printed layer / Laminating adhesive layer / Sealant layer These are some examples.

[0044] The ink used to form the printed layer is not particularly limited. Examples include toluene-containing inks, toluene-free inks, and water-based inks. From an environmental perspective, toluene-free inks and water-based inks are preferred. Examples of commercially available products that can be used as printing inks include Rio Alpha from Toyo Ink Co., Ltd., Bellflora and Flexolami Pure from Sakata Inx Co., Ltd.

[0045] As the adhesive for forming the laminate adhesive layer, known or commercially available adhesives can be used. Examples include isocyanate-based, polyurethane-based, polyester-based, polyethyleneimine-based, polybutadiene-based, polyolefin-based, and alkyl titanate-based adhesives. Among these, isocyanate-based, polyurethane-based, and polyester-based adhesives are preferred from the viewpoint of adhesion to the sealant layer and heat resistance. Examples of commercially available products that can be used as adhesives include DIC's DIC Dry LX-470EL and SP-60, and Toyo Morton's EA-N373A and EA-N373B.

[0046] As the sealant layer, a known heat-sealable resin film can be used, such as polyethylene, polypropylene, ethylene copolymer, and saturated polyester. Examples of commercially available products that can be used as sealant layers include TUX FC-S from RM Tohcello Co., Ltd. and FHK2 from Futamura Chemical Co., Ltd.

[0047] The laminate of the present invention can be manufactured by a method that includes the step of laminating a laminate adhesive layer and a sealant layer onto a resin layer or a printed layer formed thereon as needed, using known methods such as dry lamination or extrusion lamination. <Package> The laminate of the present invention can also be used as a packaging bag (bag body) by, for example, heat-sealing opposing laminate adhesive layers or heat-seal layers together. Any form of bag body can be used, such as a two-sided bag, a three-sided bag, a gusseted bag, a side-seal bag, a stand-up pouch, or a stand-up zipper bag.

[0048] The packaging material is not limited to the contents and can be used in a wide range of applications, including food and beverages, pharmaceuticals, cosmetics, chemicals, and general merchandise.

[0049] <Method for separating and recovering laminated materials> The laminate and packaging of the present invention can be separated and recovered from the base film and sealant layer by immersing them in water at 20-50°C. There are no particular restrictions on the type of water used; any water between 20 and 50°C will suffice. This can include tap water, recycled water, distilled water, ion-exchanged water, or water obtained through various methods.

[0050] The time for immersing the laminate in water depends on the structure of the laminated film, but generally it is preferable to be in the range of 15 minutes to 3 hours, taking into account the time required for water to sufficiently penetrate the resin layer.

[0051] The immersion in water may be performed once or in several stages. That is, the separated film may be collected after one immersion, or it may be collected after several immersions. It is also preferable to appropriately add known processes such as drying during this process.

[0052] In the water from step 1, the separated single-layer films and residues such as anchor coating agents, reactive adhesives, and inorganic compounds are suspended or dissolved. After removing these from the stripping solution, they are separated and recovered.

[0053] One example of a specific method is to separate lighter plastics such as polypropylene and polyethylene (floating material) from heavier condensation-based films such as polyester and polyamide in a flotation separation process, removing the heavier material. Next, the recovered plastics are washed and dewatered in a washing and dewatering process, and plastics with different specific gravities are separated by centrifugal separation.

[0054] Further separation is possible by changing the specific gravity by appropriately altering the mixing ratio of the liquids used in suspension separation, such as water and organic solvents.

[0055] Each separated component can be solidified after drying and reused as a recycled product, or as a raw material for recycled plastics.

[0056] <Example Test> [Lamination process] As a laminating adhesive, DIC's DIC Dry LX-470EL and SP-60 (LX-470EL / SP-60 = 1 / 1 (mass ratio)) were prepared with a solvent (ethyl acetate) to a concentration of 30% by mass. The laminate adhesive was applied to the surface of the resin layer of the laminated film using a bar coater No. 6, and dried at 80°C for 10 seconds to form a laminate adhesive layer with a film thickness (dry thickness) of 3 μm.

[0057] A sealant layer (unstretched polyethylene film (manufactured by RM Tohcello Co., Ltd., product name "TUX FC-S", thickness 50 μm)) was dry-laminated onto a laminate adhesive layer at a nip pressure of 490 kPa on a metal roll heated to 80°C, and the laminate was aged at 40°C for 3 days to obtain a laminate. The laminate has a layer structure consisting of a base film, an anchor coat layer, a resin layer, an adhesive layer, and a sealant layer. [Normal Lamination Strong Measurement] A 15mm wide test specimen was cut from the fabricated laminate and conditioned in a 23°C, 50%RH atmosphere for 24 hours. In the same atmosphere, the peel strength at the interface between the unstretched polyethylene film and the water-soluble resin layer of the laminated film was measured using a tensile testing machine (Shimadzu Corporation "AGS-100B") with the T-type (90°) method at a tensile speed of 300mm / min. The measurement result was defined as the normal laminate strength (unit: N / 15mm). [Water-activated laminate for strong measurement] Under the same conditions as for measuring the strength of a normal laminate, the peel strength was measured while attaching water-soaked cotton wool to the peel interface, and the measurement result was defined as the water-applied laminate strength (unit: N / 15mm).

[0058] In the laminated film of the present invention, from the viewpoint of suppressing delamination, regardless of whether or not there is a printed layer, the normal lamination strength measured by the above method is preferably 1.20 N / 15 mm or more, more preferably 1.30 N / 15 mm or more, and even more preferably 1.50 N / 15 mm or more. Furthermore, in the laminated film of the present invention, from the viewpoint of separation properties when immersed in water, it is preferable that the water-laminate strength measured by the above method is 0.20 N / 15 mm or less, and more preferably 0.15 N / 15 mm or less.

[0059] [Evaluation of film separation properties] A 30mm x 30mm test piece was cut from the prepared laminate, and the test piece was placed in 300ml of water maintained at 40°C in a 500ml glass beaker, and left to stand for 2 hours while completely immersed. After that, the test piece was removed from the water and the separation of the film was checked. If the base film and sealant layer were completely separated, it was evaluated as "○" (good), and if they were not separated, it was evaluated as "×" (bad).

[0060] [Oxygen permeability] Using a Mokon oxygen barrier analyzer (OX-TRAN 2 / 20MH), the oxygen permeability of the laminated film was measured in an atmosphere of 20°C and 65% relative humidity according to the JIS K7126-2 method. The measurement was performed with the water-soluble resin layer of the laminated film facing the cell body. The oxygen permeability is preferably 15 ml / m²·day·MPa or less, and more preferably 10 ml / m²·day·MPa or less.

[0061] <Examples> Examples and comparative examples are shown below to give a more detailed explanation of the features of the present invention. However, the embodiments of the present invention are not limited to these. [Base film] The following films were used as the base film.

[0062] Unitika Corporation emblem ONU-15 (polyamide resin film) Unitika Corporation's Emblet PET-12 (polyester resin film) [Water-soluble resin] The following water-soluble resins were used. <Polyvinyl alcohol> POVAL JF-05 manufactured by Nippon Vinegar Co., Ltd. (viscosity 5.5 mPa·s, degree of saponification 98.5 mol%) POVAL JF-10 manufactured by Nippon Vinegar Co., Ltd. (viscosity 11.0 mPa·s, degree of saponification 98.5 mol%) POVAL JP-05 manufactured by Nippon Vitro Valve Co., Ltd. (viscosity 5.0 mPa·s, degree of saponification 88.0 mol%) <Ethylene-vinyl alcohol copolymer> Soanol 16DX manufactured by Mitsubishi Chemical Corporation (resin concentration 15 wt%, viscosity 390 mPa·s) [Inorganic compounds] The following inorganic compounds were used. Aerosil 200 (silica compound) manufactured by Nippon Aerosil Co., Ltd. Aerosil 90G (silica compound) manufactured by Nippon Aerosil Co., Ltd. Kunimine Industries Co., Ltd.'s Kunipia-G (layered silicate mineral) [Example 1] (1) Preparation of coating for resin layer formation 10.1 kg of deionized water (less than 0.7 μS / cm) and 1.0 kg of polyvinyl alcohol (JF-05) as a water-soluble resin component were added to a dispersion vessel. The mixture was heated to 95°C under low-speed stirring (800 rpm, peripheral speed 2 m / min), and then stirred at the same temperature for 30 minutes to dissolve the polyvinyl alcohol. After that, it was cooled to 60°C to obtain a 9.0 mass% polyvinyl alcohol aqueous solution. To this polyvinyl alcohol aqueous solution, 4.5 kg of an alcohol aqueous solution (deionized water / 2-propanol = 4 / 1 (mass ratio)) mixed with deionized water and 2-propanol was added over 10 minutes, and the stirring was switched to high-speed stirring (1600 rpm, peripheral speed 4 m / min) for 20 minutes to obtain a 6.4 mass% polyvinyl alcohol aqueous solution.

[0063] To the obtained aqueous solution of polyvinyl alcohol, 0.03 kg of Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., was added as an inorganic compound. After the addition was complete, the mixture was stirred at high speed (1600 rpm, peripheral speed 4 m / min) at 60°C for 60 minutes. Subsequently, 1.4 kg of 2-propanol was added over 10 minutes, and the mixture was cooled to room temperature to obtain the preparation solution.

[0064] To this preparation solution, 0.002 kg of a nonionic surfactant (SH3746, manufactured by Toray Dow Corning) was added to a concentration of 0.01% by mass, and the mixture was dispersed using a high-pressure dispersion device (ultra-high-pressure homogenizer, manufactured by Microfluidizer Corporation) at a pressure of 100 N / cm². 2 The mixture was processed under the specified conditions. Next, 3.0 kg of an alcohol aqueous solution (deionized water / 2-propanol = 1 / 1.2 (mass ratio)) prepared by mixing deionized water and 2-propanol was added over 10 minutes to achieve a final solid content concentration of 5.0% by mass. The mixture was then stirred at high speed (1600 rpm, peripheral speed 4 m / min) for 20 minutes to obtain 20 kg of paint for resin layer formation. The mass ratio of inorganic compound to water-soluble resin (inorganic compound / resin) in the obtained paint was 3 / 97. (2) Anchor coat layer formation process As an anchor coating agent, 0.3 kg of a mixture of Toyo Morton Co., Ltd.'s EL-510-1-17K and CAT-87RT (EL-510-1-17K / CAT-87RT = 5 / 1 (mass ratio)) was prepared with 4.0 kg of solvent (toluene / MEK / isobutyl acetate = 5 / 4 / 1 (mass ratio)) to a concentration of 4% by mass.

[0065] The anchor coating agent was applied to the surface of a polyamide resin film (Emblem ONU-15, manufactured by Unitika Corporation) using a bar coater No. 3, and dried in a hot air dryer at 80°C for 1 minute to form an anchor coating layer. The dry thickness of this anchor coating layer was 0.03 μm. (3) Resin layer formation process On the above anchor coat layer, a resin layer-forming coating was applied using gravure coating (Hirano Techseed test coater, microgravure coating method, coating speed 5 m / min, drying temperature 80°C) to form a water-soluble resin layer and obtain a laminated film. The thickness (dry thickness) of the resin layer was 0.3 μm.

[0066] [Examples 2-8, Comparative Examples 1-3] Laminated films for Examples 2-8 and Comparative Examples 1-3 were manufactured under the same conditions as in Example 1, except that the conditions for the base film, water-soluble resin, inorganic compound, and coating layer thickness were changed as shown in Table 1. For each of the manufactured laminated films for Examples and Comparative Examples, the normal lamination strength, wet lamination strength, separation properties of the laminate film, and oxygen permeability were measured using the method described above, and the results are shown in Table 1.

[0067] [Examples 9 and 10] Laminated films of Examples 9 and 10 were manufactured under the same conditions as in Example 1, except that an ethylene-vinyl alcohol copolymer solution (Soanol 16DX) was used instead of an aqueous polyvinyl alcohol solution, and the conditions for the base film and inorganic compound were changed as shown in Table 1. For each of the laminated films manufactured in each example, the normal lamination strength, wet lamination strength, separation properties of the laminate film, and oxygen permeability were measured using the method described above, and the results are shown in Table 1.

[0068] [Table 1]

[0069] The laminated films of Examples 1 to 10, having a resin layer containing an inorganic compound in the ratio specified in this application in a laminate with a sealant layer, exhibit a sufficiently high normal lamination strength and a sufficiently low wet lamination strength, making them suitable for use as various types of packaging. At the same time, the base film and the sealant layer were easily separated by immersion in water.

[0070] In Comparative Example 1, the laminated film had a low water-laminate strength because the resin layer was formed of low-viscosity polyvinyl alcohol, and it separated easily when immersed in water. However, because the resin layer did not contain inorganic compounds, it also had low normal laminate strength, and there was a risk of delamination.

[0071] The laminated film of Comparative Example 2 did not contain an inorganic compound in the resin layer, resulting in insufficient lamination strength both under normal conditions and with water, raising concerns about delamination. Furthermore, it did not completely separate even when immersed in water.

[0072] In Comparative Example 3, the laminated film had a slightly reduced normal lamination strength because the mass ratio of the inorganic compound to the water-soluble resin in the water-soluble resin layer exceeded the range specified in the present invention. Furthermore, because the water-lamination strength was high, it did not completely separate even when immersed in water.

Claims

1. A laminated film in which at least a base film / anchor coat layer / resin layer is laminated in this order, A laminated film characterized in that the resin layer contains an inorganic compound and a water-soluble resin, and the mass ratio of the inorganic compound to the water-soluble resin (inorganic compound / water-soluble resin) is 3 / 97 to 45 / 55.

2. The laminated film according to claim 1, wherein the water-soluble resin contains polyvinyl alcohol and / or an ethylene-vinyl alcohol copolymer.

3. The laminated film according to claim 1 or 2, wherein the inorganic compound is an inorganic layered compound.

4. The laminated film according to claim 1 or 2, wherein the base film is a polyamide resin film or a polyester resin film.

5. An oxygen permeability of 15 ml / (m³) measured under conditions of 20°C and 65% RH is observed. ２ The laminated film according to claim 1 or 2, wherein the pressure is less than or equal to (day MPa).

6. A laminated film for packaging using the laminated film according to claim 1 or 2.

7. A laminate in which a laminate adhesive layer and a sealant layer are laminated in this order on the resin layer surface of the laminated film described in claim 1.

8. A laminate in which a printing layer, a laminating adhesive layer, and a sealant layer are laminated in this order on the resin layer surface of the laminated film according to claim 1.

9. The normal lamination strength is 1.20 N / 15 mm or higher, and It is characterized by having a water-applied laminating strength of 0.20 N / 15 mm or less. The laminate according to claim 7 or 8.

10. A separation and recovery method for recovering a separated base film by immersing the laminate according to claim 7 or 8 in water at 20 to 50°C.

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