Laminate and producing method thereof

Abstract

To provide a laminate having heat resistance, glossiness, slipping property, adhesiveness, solvent resistance, and low odor.SOLUTION: A laminate having a heat seal layer, a substrate, and a varnish layer in this order, wherein the varnish layer is a layer cured by electron beam of an electron beam curable composition containing (meth)acrylate compounds, and the (meth)acrylate compounds contain compounds having two or more (meth)acryloyl groups in the molecule, comprising 80 mass% or more of the total amount of the electron beam curable composition, and the electron beam curable composition does not substantially contain any photopolymerization initiator, and the varnish layer has a hardness of 100 to 180 MPa according to nanoindentation method, and a recovery rate of 77 to 100% according to nanoindentation method.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a laminate and a method for manufacturing the laminate.

Background Art

[0002] In recent years, in the field of the printing industry, from the viewpoints of shortening the process time by instant drying, reducing the environmental load and improving the work safety by non-volatile organic compound (Non-VOC), and realizing strong coating film physical properties by crosslinking reaction, the use of curing technology by active energy rays has been expanding.

[0003] The utilization of active energy ray curing technology, which started from the commercial printing field based on paper substrates such as leaflets and posters, has been developed into various fields due to the development of printing technology including printing machines and printing inks, and the application fields are being expanded to various film substrates, and the use as packaging materials for food, cosmetics, toys, and other packaging products for package products is expanding.

[0004] Packaging materials are configured by bonding a plurality of films with an adhesive, and most of them have a reverse printing configuration in which the printed pattern is visible through the film. However, from the viewpoints of reducing the environmental load and shortening the process time, the demand for a front printing configuration in which the outermost layer is an ink / varnish layer is expanding.

[0005] Generally, in a packaging material having a front printing configuration, an overcoat varnish is applied for the purpose of protecting the ink coating film, but sufficient coating film strength cannot be obtained with conventional solvent or aqueous heat-drying type overcoat varnishes. Therefore, an active energy ray-curable varnish having strong coating film physical properties is used.

[0006] However, among packaging materials having a front printing configuration, when a heat seal layer is further provided, since it is processed at a high temperature from above the ink / varnish layer on the outermost layer, even when an active energy ray-curable varnish is used, cracks and peeling are likely to occur in the ink / varnish layer (see Patent Document 1), and there is a problem that the design and specifications of the packaging material are restricted.

[0007] Here, as the active energy ray-curable varnish, ultraviolet (UV)-curable varnish is the mainstream. However, UV-curable varnish contains a considerable amount of photoinitiator, which becomes an inert component and affects the strength and heat resistance of the cured coating film. Furthermore, in the case of packaging materials, the problem of odor derived from decomposition products of the photoinitiator is also significant. In addition, in the case of UV curing, damage to the substrate due to the heat generation of the lamp that generates ultraviolet rays is also a problem.

[0008] Under such circumstances, electron beam (EB)-curable varnish, which does not require a photoinitiator, causes little thermal damage to the substrate, and can be cured with high-energy electron beams, has attracted attention particularly in terms of heat resistance and odor.

[0009] As an index of the heat resistance and strength of the varnish layer with such a surface coating configuration, surface hardness is often used. However, in the case of packaging materials, there are many characteristics that cannot be estimated from hardness, such as the problem of cracking during processing and heat resistance during heat sealing, and evaluation of brittleness in addition to hardness is required. Particularly for the heat resistance of the varnish layer during heat sealing, not only resistance to heat applied to the varnish layer is of course required, but the varnish layer is required to resist stress due to deformation and shrinkage of the heat sealing layer by heat and stress due to the substrate trying to shrink by heat, and suppress deformation and the like. Therefore, optimization from both aspects of hardness and brittleness is necessary.

[0010] In addition, as packaging materials, glossiness, slip properties for withstanding impacts and friction during transportation, adhesion, etc. are required, and furthermore, solvent resistance for withstanding alcohol disinfection in current infectious disease countermeasures is also required.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The problem to be solved by the present invention is to provide a laminate having heat resistance, glossiness, slipperiness, solvent resistance, and low odor properties.

Means for Solving the Problems

[0013] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the laminate shown below, and have completed the present invention.

[0014] That is, the present invention is a laminate having a heat-sealing layer, a base material, and a varnish layer in this order, wherein the varnish layer is a layer obtained by curing an electron beam-curable composition containing a (meth)acrylate compound with an electron beam, the (meth)acrylate compound contains 80% by mass or more of a compound having two or more (meth)acryloyl groups in the molecule in the total amount of the electron beam-curable composition, the electron beam-curable composition substantially does not contain a photoinitiator, and the varnish layer has a hardness of 100 to 180 MPa by the nanoindentation method and a recovery rate of 77 to 100% by the nanoindentation method. The present invention relates to a laminate.

[0015] The present invention also relates to the above laminate having a printing layer further between the base material and the varnish layer.

[0016] The present invention also relates to the above laminate, wherein the (meth)acrylate compound contains alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate.

[0017] The present invention also relates to the above laminate, wherein the electron beam-curable composition further contains an extender pigment.

[0018] The present invention also relates to the above laminate, wherein the electron beam-curable composition further contains resin fine particles.

[0019] The present invention also relates to the above laminate, wherein the electron beam curable composition further contains a leveling agent.

[0020] The present invention also relates to a packaging material comprising the above laminate.

[0021] The present invention also relates to a method for producing the above laminate, wherein the conditions for curing with an electron beam are an acceleration voltage of 50 to 200 kV and an irradiation dose of 15 to 200 kGy.

Effect of the Invention

[0022] According to the present invention, it has been possible to provide a laminate having heat resistance, glossiness, slipperiness, solvent resistance, and low odor.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments for carrying out the present invention will be described in detail. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist thereof.

[0024] The terms used in this specification will be explained. "(Meth)acryloyl" means acryloyl and / or methacryloyl (methacryloyl), and "(meth)acrylate" means acrylate and / or methacrylate (methacrylate). "Active energy ray" means an energy ray having the property of causing a chemical change such as a chemical reaction in the irradiated material by irradiation, such as ultraviolet rays and electron beams. Also, "PO" represents "propylene oxide" and "EO" represents "ethylene oxide".

[0025] <Laminate> The laminate of the present invention is a laminate having a heat seal layer, a base material, and a varnish layer in this order, and the varnish layer is a layer obtained by curing an electron beam curable composition containing a (meth)acrylate compound with an electron beam. The laminate of the present invention can be used for various applications. Among them, it can be preferably used as a packaging material.

[0026] <Base material> The base material in the present invention is not particularly limited, and known ones can be used, but a film base material is preferred. For example, polyolefin base materials such as polyethylene and polypropylene, polyester base materials such as polyethylene terephthalate and polylactic acid, polycarbonate base materials, polystyrene base materials such as polystyrene, AS resin, and ABS resin, nylon base materials, polyamide base materials, polyvinyl chloride base materials, polyvinylidene chloride base materials, cellophane base materials, paper base materials, aluminum base materials, etc., or film base materials made of these composite materials can be mentioned. Among them, polyolefin-based films are preferred from the viewpoint of recyclability. In addition, an evaporated base material obtained by evaporating an inorganic compound such as silica, alumina, or aluminum onto a film base material can also be used. Further, the evaporated surface may be subjected to a coating treatment with polyvinyl alcohol or the like. It is preferable that the surface of the base material to be printed (the surface in contact with the printing layer) is subjected to an easy adhesion treatment. Specific examples of the easy adhesion treatment include corona discharge treatment, ultraviolet / ozone treatment, plasma treatment, oxygen plasma treatment, primer treatment, etc. Also, in the case of a polyethylene terephthalate base material, when sufficient adhesion cannot be obtained, surface treatments such as acrylic coating treatment, polyester treatment, and polyvinylidene chloride treatment may be performed.

[0027] As the base material, a paper base material may be used. The paper base material is ordinary paper or cardboard, etc., and there is no particular specification for the film thickness. The thickness of the paper base material can be, for example, 0.2 mm to 1.0 mm, 20 to 150 g / m 2 and those can be used, and the printing surface may be subjected to an easy adhesion treatment. The paper base material may be subjected to an evaporation treatment with a metal such as aluminum on the surface for the purpose of imparting design. Also, the paper base material may be subjected to a surface coating treatment with an acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resin, and further, a surface treatment such as corona treatment may be performed. For example, specific examples of the surface-treated paper base material include coated paper and art paper.

[0028] <Heat seal layer> The heat seal layer in the present invention is not particularly limited, and known ones can be used. For example, polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, copolymerized polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate copolymer, ethylene-(meth)acrylic acid copolymer, ionomer, and other polyolefin resins can be mentioned. Among them, from the viewpoint of recyclability, polypropylene-based resins are preferred, and unstretched polypropylene is particularly preferred from the viewpoint of heat sealability. The thickness of the heat seal layer is not particularly limited, but considering the processability and heat sealability of the laminate, etc., a range of 10 to 60 μm is preferred, and a range of 15 to 40 μm is more preferred. In addition, the method of laminating the heat seal layer is not particularly limited. For example, a method of laminating an adhesive layer and a sealant film by heat (thermal lamination, dry lamination), a method of melting a sealant resin and extruding it onto the adhesive layer and cooling and solidifying it for lamination (extrusion lamination method), etc. can be mentioned.

[0029] <Varnish layer> The varnish layer in the present invention is a layer obtained by curing an electron beam-curable composition containing a (meth)acrylate compound with an electron beam.

[0030] The electron beam-curable composition in the present invention contains 80% by mass or more of a (meth)acrylate compound in the total amount of the composition. The content of the (meth)acrylate compound is preferably 80 to 99% by mass, preferably 85 to 98% by mass, and particularly preferably 90 to 97% by mass in the total amount of the composition.

[0031] In this specification, the (meth)acrylate compound means a compound having a (meth)acryloyl group in the molecule. Specific examples of the (meth)acrylate compound that can be used to constitute the electron beam curable composition in the present invention include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,2-dodecanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol (200) di(meth)acrylate, polyethylene glycol (300) di(meth)acrylate, polyethylene glycol (400) di(meth)acrylate, polyethylene glycol (600) di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, EO-modified 1,6-hexanediol di(meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, (neopentyl glycol-modified) trimethylolpropane di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, EO-modified bisphenol A di(meth)acrylate, PO-modified bisphenol A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, dicyclopentanyl di(meth)acrylate, and trifunctional (meth)acrylate compounds such as tris(2-hydroxyethyl) isocyanurate di(meth)acrylate. Trifunctional (meth)acrylate compounds such as trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, glycerin propoxytriacrylate, PO-modified trimethylolpropane tri(meth)acrylate, ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate, ethoxylated isocyanuric acid tri(meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, and pentaerythritol tri(meth)acrylate. Tetrafunctional radical (meth)acrylate compounds such as pentaerythritol tetra(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate, Pentafunctional (meth)acrylate compounds such as dipentaerythritol penta(meth)acrylate, Hexafunctional (meth)acrylate compounds such as dipentaerythritol hexa(meth)acrylate, etc. can be mentioned.

[0032] Also, as the (meth)acrylate compound, urethane acrylates such as aliphatic urethane acrylate and aromatic urethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, etc. can be used.

[0033] (Meth)acrylate compounds may be used alone or in combination of two or more.

[0034] (Meth)acrylate compounds preferably contain a polyfunctional acrylate having two or more (meth)acryloyl groups in terms of curability.

[0035] (Meth)acrylate compounds preferably contain alkylene oxide-modified (3 - 9 mol / mol) trimethylolpropane triacrylate from the viewpoint of heat resistance. By containing alkylene oxide-modified (3 - 9 mol / mol) trimethylolpropane triacrylate, the hardness and recovery rate of the varnish layer become good, and the heat resistance of the laminate becomes good. The amount of alkylene oxide modification of alkylene oxide-modified trimethylolpropane triacrylate is more preferably 3 - 6 mol / mol. Furthermore, the alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate is preferably ethylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate or propylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate, more preferably ethylene oxide-modified (3 to 6 mol / mol) trimethylolpropane triacrylate or propylene oxide-modified (3 to 6 mol / mol) trimethylolpropane triacrylate, and particularly preferably ethylene oxide-modified (3 mol / mol) trimethylolpropane triacrylate or propylene oxide-modified (3 mol / mol) trimethylolpropane triacrylate. The content of the alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate is preferably 20 to 90% by mass in the total amount of the electron beam curable composition.

[0036] Also, from the viewpoint of heat resistance, the (meth)acrylate compound preferably contains dipentaerythritol hexaacrylate. By containing dipentaerythritol hexaacrylate, the hardness of the varnish layer is improved and the heat resistance of the laminate becomes good. When dipentaerythritol hexaacrylate is contained, it is preferably 5 to 50% by mass in the total amount of the electron beam curable composition.

[0037] Also, from the viewpoint of gloss, the (meth)acrylate compound preferably contains tripropylene glycol diacrylate. By containing tripropylene glycol diacrylate, the gloss of the laminate becomes good. When tripropylene glycol diacrylate is contained, it is preferably 5 to 50% by mass in the total amount of the electron beam curable composition.

[0038] The electron beam curable composition in the present invention may further contain an extender pigment, resin fine particles, and a leveling agent.

[0039] <Extender pigment> The electron beam curable composition in the present invention preferably further contains an extender pigment. By including an extender pigment, the film-forming property of the coating film is enhanced and the slipperiness is improved. Specific examples of the extender pigment include silica, barium sulfate, alumina white, calcium carbonate, magnesium carbonate, aluminum silicate, magnesium silicate, silicon dioxide, and aluminum hydroxide. Further, these may be used alone or in combination of two or more. Preferably, the extender pigment is silica. The content of the extender pigment is preferably 0.1 to 10% by mass, more preferably 1.0 to 5% by mass, based on the total amount of the electron beam curable composition.

[0040] <Resin fine particles> The electron beam curable composition in the present invention preferably further contains resin fine particles. By including resin fine particles, the slipperiness and heat resistance are improved.

[0041] Specific examples of the resin fine particles include urethane resin fine particles, acrylic resin fine particles, acrylic-styrene copolymer resin fine particles, polycarbonate resin fine particles, polyethylene resin fine particles, polystyrene resin fine particles, silicone resin fine particles, melamine resin fine particles, melamine-benzoguanamine resin fine particles, melamine-benzoguanamine-formaldehyde resin (condensate) fine particles, polypropylene resin fine particles, amide resin fine particles, polytetrafluoroethylene resin fine particles, and benzoguanamine resin fine particles. These may be used alone or, if necessary, in combination of two or more.

[0042] From the viewpoints of slipperiness, heat resistance, and glossiness, the content of the resin fine particles is preferably 0.1 to 5% by mass, more preferably 0.25 to 3% by mass, based on the total mass of the electron beam curable composition.

[0043] The resin fine particles may be obtained as commercially available products or produced by known manufacturing methods. For example, specific examples of urethane resin fine particles include Art Pearl C-1000 transparent, Art Pearl C-600 transparent, Art Pearl C-400 transparent, Art Pearl C-800, and Art Pearl MM-120T manufactured by Negami Kogyo Co., Ltd. Further, the urethane resin fine particles may have a crosslinked structure. Specific examples of urethane resin fine particles having a crosslinked structure include crosslinked urethane resin fine particles such as Art Pearl JB-800T, Art Pearl JB-600T, Art Pearl P-800T, and Art Pearl P-400T manufactured by Negami Kogyo Co., Ltd.

[0044] Specific examples of acrylic resin fine particles include Art Pearl J4PY and Art Pearl J5PY manufactured by Negami Kogyo Co., Ltd., and Guns Pearl GB08S manufactured by Aika Kogyo Co., Ltd. Further, examples include Eposter MA1002, Eposter MA1004, Eposter MA1006, and Eposter MA1010 manufactured by Nippon Shokubai Co., Ltd., Toughick FH-S005, Toughick FH-S008, Toughick FH-S010, Toughick FH-S015, Toughick FH-S020 manufactured by Toyobo Co., Ltd., and Chemisnow MX-80H3wT, MX-150, MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MX-2000, MX-3000, etc. manufactured by Soken Chemical & Engineering Co., Ltd.

[0045] Specific examples of acrylic-styrene copolymer resin fine particles include Eposter MA2003 manufactured by Nippon Shokubai Co., Ltd., and FS-102, FS-201, FS-301, MG-451, MG-351, etc. manufactured by Nippon Paint Industrial Coatings Co., Ltd.

[0046] Specific examples of polycarbonate resin fine particles include the fine particles described in JP-A-2014-125495, the fine particles obtained by the production method described in JP-A-2011-26471, the fine particles obtained by the method described in JP-A-2001-213970, etc.

[0047] Specific examples of silicone resin fine particles include KMP-594, KMP-597, KMP-598, KMP-600, KMP-601, KMP-602 manufactured by Shin-Etsu Chemical Co., Ltd., Trefl E-506S, EP-9215 manufactured by Toray Dow Corning Co., Ltd., and the Tosuperal series of Momentive, etc.

[0048] Specific examples of polyethylene resin fine particles include Mipelon XM-220, XM221U manufactured by Mitsui Chemicals, Inc., Flow Beads LE-1080 manufactured by Sumitomo Seika Chemicals Co., Ltd., Cerafloure991 manufactured by BYK-Chemie Japan Co., Ltd., etc.

[0049] Specific examples of polystyrene-based fine particles include Chemisnow SX-130H, SX-350H, SX-500H manufactured by Soken Chemical & Engineering Co., Ltd., etc.

[0050] Specific examples of melamine resin fine particles include Epotar SS, Epotar S, Epotar FS, Epotar S6, Epotar S12 manufactured by Nippon Shokubai Co., Ltd., etc.

[0051] Specific examples of melamine-benzoguanamine resin fine particles include Epotar M30 manufactured by Nippon Shokubai Co., Ltd.

[0052] Specific examples of benzoguanamine resin fine particles include Epotar MS, Epotar M05, Epotar L15 manufactured by Nippon Shokubai Co., Ltd., etc.

[0053] Specific examples of polytetrafluoroethylene resin fine particles include SST-3T1-RC of Shamrock Technologies.

[0054] The resin fine particles are preferably at least one selected from the group consisting of silicone resin fine particles, acrylic resin fine particles, polytetrafluoroethylene resin fine particles, and polyethylene resin fine particles, and more preferably at least one selected from the group consisting of acrylic resin fine particles and polytetrafluoroethylene fine particles. When silicone resin microparticles, acrylic resin microparticles, or polyethylene resin microparticles are used, particle size control is easy, the sphericity is high, and excellent dispersibility can be easily obtained. In addition, these resin microparticles have high transparency and can provide good slip properties while minimizing the decrease in gloss. When polytetrafluoroethylene resin microparticles are used, excellent heat resistance and slip properties can be obtained due to their chemical stability, high melting point, and low friction coefficient.

[0055] From the viewpoints of slip properties, heat resistance, and gloss, it is preferable to use resin microparticles with an average particle diameter of 2 to 12 μm, and more preferably 5 to 10 μm. The resin microparticles may be in the form of particles composed of various resins or particles with their surfaces coated with various resins. Also, the resin microparticles may be used alone or in combination of two or more.

[0056] <Leveling agent> The electron beam curable composition in the present invention preferably further contains a leveling agent. By including a leveling agent, the slip properties are improved. As the leveling agent, from the viewpoint of the surface slipperiness, it is preferable to contain a silicone-modified acrylate compound. Also, the leveling agent may be used alone or in combination of two or more. The content of the leveling agent is preferably 0.1 to 3% by mass, and more preferably 0.4 to 1.5% by mass in the total amount of the electron beam curable composition.

[0057] <Other components> The electron beam curable composition in the present invention can use an antistatic agent, a surfactant, an antifoaming agent, an ultraviolet absorber, an antioxidant, a curing agent, a plasticizer, a wetting agent, an adhesion aid, an antifoaming agent, an antistatic agent, a trapping agent, an antiblocking agent, a preservative, etc. within the range where the effects of the present invention are not reduced. These can be added as needed.

[0058] The electron beam curable composition of the present invention substantially does not contain a photoinitiator. Here, "substantially does not contain" in the present invention means that it is not intentionally added and the content due to unintentional addition is less than 1% by mass. Unintentional addition includes cases where it is contained in trace amounts in each raw material, or contamination in the manufacturing process of the composition or the process of producing printed matter.

[0059] Further, the electron beam curable composition of the present invention substantially does not contain an organic solvent. There is a concern that the organic solvent used as a viscosity modifier for printing ink contains MOSH / MOAH which are persistent organic pollutants, and since it is expected to reduce the environmental load and improve work safety by not containing volatile components (Non-VOC), in the present invention, it is preferable not to substantially contain an organic solvent.

[0060] <Method for producing electron beam curable composition> As a method for producing the electron beam curable composition of the present invention, a (meth)acrylate compound and other components such as resin fine particles used as necessary can be produced by mixing and stirring them for about 30 minutes to 3 hours using a mixer or the like. In addition, as the (meth)acrylate compound, two or more kinds of (meth)acrylate compounds may be mixed and stirred in advance, and then other components such as resin fine particles used as necessary may be added for production.

[0061] <Manufacture of varnish layer> Examples of the method for printing or coating the electron beam curable composition include coating using a roll coater, gravure coater, flexo coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, transfer roll coater, kiss coater, curtain coater, cast coater, spray coater, die coater, etc., and printing using offset printing (ordinary lithography using dampening water and waterless lithography not using dampening water), flexography, gravure printing, screen printing, etc. In addition, in inline printing and offline printing, various inks such as UV-curable, electron beam-curable, heat-drying, evaporation-drying, oxidation-polymerization, penetration-drying, heat-polymerization, two-component-curable, liquid toner, and powder toner inks can be used in combination as needed.

[0062] <Electron beam irradiation conditions> The electron beam-curable composition of the present invention is printed by various printing methods and then cured through an electron beam irradiator to form a printed layer. The electron beam used for curing is adjusted to an electron beam under the conditions of an accelerating voltage of 50 to 200 kV, more preferably 80 to 110 kV, and an irradiation dose of 15 to 60 kGy, more preferably 20 to 45 kGy, considering the balance between damage to the film and the curability of the electron beam-curable composition. When the irradiation dose is 15 to 60 kGy, sufficient film strength can be obtained, and problems due to damage to the film such as film strength reduction, odor, and yellowing can be suppressed.

[0063] <Printed layer> The laminate in the present invention may further have a printed layer between the base material and the varnish layer. The printed layer is obtained by printing ink and, if necessary, drying or curing it. As the ink, known inks such as solvent-based ink, water-based ink, and active energy ray-curable ink can be used, but considering the productivity of the laminate, etc., an active energy ray-curable ink is preferably used, an electron beam-curable ink is more preferably used, and a solvent-free electron beam-curable ink is particularly preferably used. As a method of printing ink on the base material, known printing methods such as offset printing, gravure printing, flexographic printing, and inkjet printing can be selected.

[0064] <Method for manufacturing laminate> As a method for manufacturing the laminate in the present invention, either a method of creating a base material having a varnish layer and then laminating a heat-seal layer or a method of creating a varnish layer on a base material having a heat-seal layer can be used. Here, when creating the varnish layer, the electron beam irradiated may affect the heat seal layer depending on the intensity of the electron beam, the type of substrate, and the thickness, and the heat seal strength may decrease. In such a case, after creating the substrate having the varnish layer, by adopting a method of laminating the heat seal layer, a laminate can be manufactured without being affected.

[0065] <Hardness of the varnish layer in the laminate> The varnish layer in the laminate of the present invention has a hardness of 100 to 180 MPa by the nanoindentation method. The hardness by the nanoindentation method is a value of the indentation hardness measured using a microarea mechanical property evaluation apparatus (nanoindenter), and in the present invention, it is a value measured using a Hysitron TI Premier (manufactured by Bruker). Since the nanoindenter indents only the very surface layer of the laminate, it is not affected by the substrate, and the mechanical properties of only the varnish layer, which is a thin film, can be measured. In other measurement methods, the indentation load and displacement are too large, making it difficult to measure only the thin film layer. In the present invention, it indicates the hardness of only the varnish layer.

[0066] The method for measuring the indentation hardness (H) of the varnish layer is as follows. As the indenter of the nanoindenter, a triangular pyramid-shaped Berkovich indenter is used. The Berkovich indenter is indented into the measurement sample under the indentation conditions described below, and the indentation depth h (nm) with respect to the indentation load F (μN) is continuously measured to create a load-displacement curve. The maximum indentation load Fmax (μN) is obtained from the created load-displacement curve. Then, the hardness is obtained by dividing the maximum indentation load Fmax (μN) by the contact projected area Ac (μm 2 ) at that time. That is, H = Fmax / Ac. Here, Ac is the contact projected area obtained by correcting the curvature of the indenter tip by the apparatus standard method using fused quartz as the standard sample. The contact projected area Ac is calculated from the contact depth h (nm), and Ac = 24.56h 2 is. The indentation conditions are as follows: at room temperature, first press the indenter to a depth of 300 nm for 5 seconds (i.e., 60 nm / s), then hold it at a depth of 300 nm for 2 seconds, and finally unload it to 0 nm in 5 seconds.

[0067] <Recovery rate of the varnish layer in the laminate> In the laminate of the present invention, the recovery rate of the varnish layer by the nanoindentation method is 77 - 100%. The recovery rate by the nanoindentation method is a value representing the recovery state of the coating film after indentation, measured using a micro-region mechanical property evaluation device (nanoindenter). In this application, it is a value measured using the same device as that used to measure the hardness of the varnish layer in the laminate. The larger the number, the more it absorbs the indentation and the easier it is to return to the original state of the coating film. In the present invention, it represents the brittleness of the coating film.

[0068] The method for measuring the recovery rate of the varnish layer is as follows. As the indenter of the nanoindenter, a conical indenter with a conical shape is used. The conical indenter is horizontally driven on the measurement sample under the indentation conditions described below, and the indentation depth h (nm) with respect to the horizontal movement distance (μm) is continuously measured to create a horizontal distance - vertical displacement curve. The recovery rate (%) is obtained from the created horizontal distance - vertical displacement curve. The recovery rate (%) is an index indicating the degree of recovery of the coating film indented by the horizontal drive of the indenter. The indentation conditions are as follows: at room temperature, in conjunction with moving the indenter horizontally at 0.4 μm / s for 6 μm, a load of up to 300 μN is applied in the vertical direction at a load rate of 20 μN / s. Also, after the measurement, the depth of the indentation was measured by warping the sample at the same location with a weak load that does not deform the shape. From the measurement data obtained there, (Maximum vertical displacement during indentation (nm) - Maximum indentation depth after indentation (nm)) / Maximum vertical displacement during indentation (nm) × 100 = Recovery rate (%) was calculated.

Example

[0069] Examples and comparative examples are shown below to more specifically explain the present invention. However, the present invention is not limited thereto. In the examples and comparative examples, "parts" represents "parts by mass", and "%" represents "% by mass".

[0070] <Manufacture of Electron Beam Curing Composition> Details of the materials used in the following production examples, examples and comparative examples are as follows. <(Meth)acrylate Compound> ·Miramer M122: Manufactured by MIWON, LA (Lauryl Acrylate) ·TPGDA: Manufactured by Daicel Ornex, TPGDA (Tripropylene Glycol Di Acrylate) ·Miramer M300: Manufactured by MIWON, TMPTA (Trimethylolpropane Triacrylate) ·LAROMER LR 8863: BASF, TMP(EO)3TA (EO(3 moles) Modified Trimethylolpropane Triacrylate) ·Miramer M3160: Manufactured by MIWON, TMP(EO)6TA (EO(6 moles) Modified Trimethylolpropane Triacrylate) ·Miramer M3190: Manufactured by MIWON, TMP(EO)9TA (EO(9 moles) Modified Trimethylolpropane Triacrylate) ·Miramer M3150: Manufactured by MIWON, TMP(EO)15TA (EO(15 moles) Modified Trimethylolpropane Triacrylate) ·Etermer EM 2381: Manufactured by Eternal Materials, TMP(PO)3TA (PO(3 moles) Modified Trimethylolpropane Triacrylate) ·A-TMPT-6PO: Manufactured by Shin-Nakamura Chemical Industry Co., Ltd., TMP(PO)6TA (PO(6 moles) Modified Trimethylolpropane Triacrylate) ·Miramer M600: Manufactured by MIWON, DPHA (Dipentaerythritol Hexaacrylate) ·EBECRYL 130: Manufactured by Daicel Ornex, TCDDA (Tricyclodecane Diacrylate) · EBECRYL 230: Manufactured by Daicel Ornex Co., Ltd., aliphatic urethane acrylate (number of acryloyl groups: 2) · EBECRYL 8411: Manufactured by Daicel Ornex Co., Ltd., aliphatic urethane acrylate (number of acryloyl groups: 2) · SR355NS: Manufactured by Sartomer Co., Ltd., ditrimethylolpropane tetraacrylate <Resin microparticles> · Sekisui Tech Polymer BM30X-5: Manufactured by Sekisui Chemical Co., Ltd., average particle diameter 5 μm, acrylic resin microparticles · Sekisui Tech Polymer BM30X-8: Manufactured by Sekisui Chemical Co., Ltd., average particle diameter 8 μm, acrylic resin microparticles · Sekisui Tech Polymer BM30X-12: Manufactured by Sekisui Chemical Co., Ltd., average particle diameter 12 μm, acrylic resin microparticles <Leveling agent> · TEGO Rad 2300: Manufactured by Evonik Co., Ltd., polyether-modified polydimethylsiloxane resin with acryloyl groups <Extender pigment> · AEROSIL R972: Manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 16 nm, specific surface area 110 m 2 / g, dry silica) <Photoinitiator> · OMNIRAD 1173: Manufactured by IGM Resins Co., Ltd., 2-hydroxy-2-methylpropiophenone <Pigment for ink formulation> · MOGAL E: Manufactured by Bilra Carbon Co., Ltd., pigment <Dispersant for ink formulation> · Solsperse32000: Manufactured by Lubrizol Co., Ltd., dispersant <Defoamer for ink formulation> · BYK-1790: Manufactured by BYK Co., Ltd., defoamer <Water-based overcoat varnish> JS 1269 PO Matt Resin: Manufactured by Toyo Ink Co., Ltd. <Solvent-based overcoat varnish> HW870 Aquarian A Soft Matt Varnish: Manufactured by Toyo Ink Co., Ltd.

[0071] <Manufacture of Electron Beam Curing Composition> (Production Example 1) 76.0 parts of LAROMER LR 8863, 10.0 parts of TPGDA, 10.0 parts of Miramer M600, 0.5 part of Sekisui Tech Polymer BM30X-5, 0.5 part of TEGO Rad 2300, and 3.0 parts of AEROSIL R972 were mixed at the mixing ratio, and stirred using a planetary mixer to obtain an electron beam curing composition.

[0072] (Production Examples 2 to 21) Electron beam curing compositions of Production Examples 2 to 21 were obtained in the same manner as in Example 1, except that each material was used according to the composition shown in Table 1.

[0073] (Production Example 22) 23 parts of MOGAL E, 6 parts of EBECRYL 8411, 3 parts of Miramer M122, 10 parts of TPGDA, 46.5 parts of Laromer LR 8863, 5 parts of SR355NS, 6 parts of Solsperse32000, and 0.5 part of BYK-1790 were mixed at the mixing ratio, and kneaded with a three-roll mill to prepare an electron beam curing flexographic ink.

[0074] <Manufacture of Laminate> (Example 1) Using the electron beam curing composition obtained in Production Example 1, printing was performed on a substrate by flexographic printing. Immediately after printing, the coating film was irradiated with an electron beam to form a cured coating film, and a laminate was produced. More specifically, it is as follows. The printing machine used was Flexiproof 100 manufactured by RK Print Coat Instruments. The printing conditions were a printing speed of 60 m / min, an anilox roll line number of 300 Line / inch, and an anilox roll cell volume of 13.09 cm 3 / m 2 The engraving pattern of the anilox roll was hexagonal. The plate material used was ESXQ manufactured by DuPont, and the area of the plate material was 106.8 cm 2 The coating amount of the electron beam curing composition was such that the coating amount after curing was 2.5 to 3.5 g / m 2It was printed so as to be [as described]. The electron beam irradiation was carried out using an electron beam irradiator EC250 / 15 / 180L manufactured by Iwasaki Electric Co., Ltd. under the conditions of an acceleration voltage of 110 kV and an electron beam dose of 30 kGy. As the base material, a laminated base material of a biaxially stretched polypropylene film and an unstretched polypropylene film was used. The electron beam curable composition was printed on the biaxially stretched polypropylene film side of the laminated base material. The laminated base material was produced as follows.

[0075] (Method for producing the laminated base material) An adhesive diluent was applied to a biaxially stretched polypropylene film (product name: FOR-BT, thickness 20 μm) manufactured by Futamura Chemical Co., Ltd. to volatilize the solvent. The adhesive diluent was prepared by diluting an adhesive (TM-321A / TM-321B = 2 / 1 manufactured by Toyo Morton Co., Ltd.) with ethyl acetate so that the active ingredient was 30%. The application of the adhesive diluent was carried out at room temperature using a bar coater, and the solid content application amount after solvent volatilization was adjusted to be 2.0 - 2.5 g / m 2 and adjusted and carried out. Next, the adhesive-coated surface of the above film was laminated with an unstretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., FHK 30 μm). Then, it was left in an environment of 35°C and a humidity of 60% RT - 80% RT for 24 hours to obtain a laminated base material. For the obtained laminate, the hardness and recovery rate of the varnish layer were measured by the method described above. The results are shown in Table 1.

[0076] (Examples 2 - 14, Comparative Examples 1 - 7) Except for using the types of varnish and base materials described in Table 1, laminates of Examples 2 - 14 and Comparative Examples 1 - 7 were obtained in the same manner as in Example 1. For the obtained laminates, the hardness and recovery rate of the varnish layer were measured by the method described above. The results are shown in Table 1.

[0077] (Example 15) The electron beam curable ink prepared in Production Example 22 was printed on the base material by the flexographic printing method in the same manner as the composition in Example 1, and cured with an electron beam under the same conditions as the composition in Example 1 to prepare a base material having a printed layer. On the printed surface of the substrate having the obtained printing layer, a varnish layer was created in the same manner as in Example 1, and a laminate having a printing layer between the substrate and the varnish layer was produced. For the obtained laminate, the hardness and recovery rate of the varnish layer were measured by the method described above. The results are shown in Table 1.

[0078] (Comparative Examples 8, 9) Using a commercially available overcoat varnish, printing was performed on the substrate by the flexographic printing method in the same manner as in Example 1. Immediately after printing, the coating film was dried to form a coating film, and a laminate was produced. More specifically, it is as follows. Under the same apparatus and conditions as in Example 1, the coating amount was such that the coating amount after curing was 0.9 to 1.5 g / m 2 and printing was carried out. Drying was carried out under the conditions of a temperature of 70°C and a drying time of 3 minutes. For the obtained laminate, the hardness of the varnish layer was measured by the method described above. An attempt was also made to measure the recovery rate of the varnish layer, but the strength of the varnish layer was too weak to be measured. The results are shown in Table 1.

[0079]

Table 1

[0080]

Table 1

[0081] For the obtained laminate, the following evaluations were carried out. The evaluation results are shown in Table 1.

[0082] [Heat resistance] For the obtained laminate, heating was repeated twice from the printed surface side at 180°C, 0.25 MPa, and for 1 second using a heat sealer (TP-705 Ring Seal Tester, Tester Sangyo Co., Ltd.), and cracking and peeling of the varnish layer at the heat-sealed portion were evaluated. An evaluation of 3 or more is preferable for practical use. (Evaluation criteria) 5: Slight cracking, no peeling 4: With cracks, no peeling 3: Somewhat more cracks, no peeling 2: Many cracks, no peeling 1: With peeling

[0083] [Solvent resistance] For the obtained laminate, a cotton swab immersed in a 99.5% ethanol solution was used to rub back and forth once per second, and the number of reciprocations until the surface of the cured coating film was scraped off was measured. An evaluation of 3 or more is preferably practical. (Evaluation criteria) 5: 50 times or more 4: 40 times or more and less than 50 times 3: 20 times or more and less than 30 times 2: 10 times or more and less than 20 times 1: Less than 10 times

[0084] [Slip property] For the obtained laminate, the coefficient of kinetic friction was measured with a friction measuring machine (friction measuring machine HM-3, manufactured by Toyo Seiki Seisakusho Co., Ltd., speed 100 mm / min, moving distance 50 mm, thread 63 mm×63 mm, 200 g). An evaluation of 2 or more is preferably practical. (Evaluation criteria) 3: Coefficient of kinetic friction less than 0.40 2: Coefficient of kinetic friction 0.40 or more and less than 0.45 1: Coefficient of kinetic friction 0.45 or more

[0085] [Odor] For the obtained laminate, it was cut into 89 mm×120 mm, and the intensity of the odor immediately after printing was evaluated by five people through sensory evaluation, and the evaluation was based on the average value. An evaluation of 3 or more is preferably practical. (Evaluation criteria) 4: Odor hardly felt 3: Odor slightly felt 2: Odor clearly felt 1: Odor strongly felt

[0086] Examples 1 to 15 were varnish layers using a composition in which the (meth)acrylate compound contained 80% by mass or more of a compound having two or more (meth)acryloyl groups in the molecule and substantially did not contain a photopolymerization initiator. The hardness of the laminate was 100 to 180 MPa, and the recovery rate was 77 to 100%. As a result, heat resistance, slipperiness, solvent resistance, and low odor were at practical levels. On the other hand, in Comparative Example 1, the hardness was less than 100 MPa, and the heat resistance and solvent resistance were insufficient. This is considered to be affected by the low crosslink density. In Comparative Example 2, a large amount of a compound having one (meth)acryloyl group in the molecule was used, and as a result, the hardness was low as in Comparative Example 1, and the heat resistance and solvent resistance were insufficient. In Comparative Example 3, the recovery rate was less than 77%, and the heat resistance was insufficient. This is considered to be because the hardness was in an appropriate range, but the film was brittle and had high brittleness. Comparative Example 4 contained 20% by mass of an inert resin having no (meth)acryloyl group, and the compound having two or more (meth)acryloyl groups in the molecule was less than 80% by mass of the total amount of the composition. The hardness was less than 100 MPa, and the solvent resistance and slipperiness were insufficient. This is considered to be because the inert resin that is not incorporated into the crosslinking also exists on the film surface. In Comparative Example 5, the hardness exceeded 180 MPa and the recovery rate was also less than 77%, and the heat resistance was insufficient. Further, in Comparative Example 6, although the recovery rate was within the range, the hardness exceeded 180 MPa and the heat resistance was insufficient. From Comparative Examples 5 and 6, it can be seen that simply increasing the hardness cannot satisfy the heat resistance during heat sealing. Comparative Example 7 was a system containing a photopolymerization initiator. The photopolymerization initiator and its decomposition products became inert components. In addition to being inferior in heat resistance compared to a system substantially not containing a photopolymerization initiator, the odor due to the photopolymerization initiator and its decomposition products was strong and not suitable for practical use. Comparative Examples 8 and 9 are laminates using an oil-based varnish and an aqueous varnish, which are not active energy ray curable, for the varnish layer. Compared with the active energy ray curable type, the hardness was significantly low and the recovery rate could not be measured. As a result, the heat resistance and solvent resistance were significantly inferior. Also, there was a strong odor presumably derived from residual agents and the like.

[0087] As is clear from the above, it was proved that the laminate of the present invention has heat resistance, slipperiness, solvent resistance, and low odor by setting the hardness and the recovery rate within specific ranges.

Claims

1. A laminate having a heat seal layer, a base material, and a varnish layer in this order, wherein the varnish layer is a layer obtained by curing an electron beam-curable composition containing a (meth)acrylate compound with an electron beam, the (meth)acrylate compound contains, in the total amount of the electron beam-curable composition, 80% by mass or more of a compound having two or more (meth)acryloyl groups in the molecule, the electron beam-curable composition substantially does not contain a photoinitiator, the varnish layer has a hardness of 100 to 180 MPa and a recovery rate of 77 to 100% by the nanoindentation method, a laminate.

2. The laminate according to claim 1, further having a printing layer between the base material and the varnish layer.

3. The laminate according to claim 1, wherein the (meth)acrylate compound contains alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate.

4. The laminate according to claim 1, wherein the electron beam-curable composition further contains an extender pigment.

5. The laminate according to claim 1, wherein the electron beam-curable composition further contains resin fine particles.

6. The laminate according to claim 1, wherein the electron beam-curable composition further contains a leveling agent.

7. A packaging material comprising the laminate according to any one of claims 1 to 6.

8. A method for producing the laminate according to any one of claims 1 to 6, wherein the conditions for curing with an electron beam are an acceleration voltage of 50 to 200 kV and an irradiation dose of 15 to 200 kGy.

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