Laminate and method for manufacturing laminate

Abstract

Disclosed is a laminate which includes a base material and a varnish layer that is formed on one surface of the base material, wherein: the varnish layer is formed of a cured product of an electron beam curable composition that contains a (meth)acrylate compound; the (meth)acrylate compound includes a compound that has two or more (meth)acryloyl groups in each molecule; the content of the compound that has two or more (meth)acryloyl groups in each molecule is 80 mass% or more based on the total mass of the electron beam curable composition; the electron beam curable composition does not substantially contain a photopolymerization initiator; and the varnish layer has a hardness of 100 MPa to 180 MPa as determined by a nanoindentation method, and has a recovery rate of 77% to 100% as determined by a nanoindentation method.

Description

Laminate and method for manufacturing the laminate

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to laminates and methods for making laminates.

[0002] In recent years, the use of curing technology using active energy rays has expanded in the printing industry. The use of curing technology using active energy rays enables shortening of processing time through instant drying, reduction of environmental impact and improvement of work safety through the absence of volatile components (Non-VOC), and realization of strong coating film properties through crosslinking reactions.

[0003] The active energy ray curing technology has traditionally been mainly used in the field of commercial printed materials based on paper substrates, such as flyers and posters. However, with the development of printing technology, including printing machines and printing inks, the use of the active energy ray curing technology in various fields has been considered in recent years. For example, the curing technology is also used in the field of printed materials (laminates) using various film substrates, and the laminates are increasingly being used as packaging materials for packaged products, such as packaging for food, cosmetics, and toys.

[0004] Packaging materials have a laminate structure in which multiple film substrates are bonded together with an adhesive, and are broadly classified into reverse-printed structures and front-printed structures. Conventionally, the mainstream structure has been a reverse-printed structure in which the printed image is visible through the film substrate. However, in recent years, from the perspectives of reducing environmental impact and shortening processing time, there has been an increasing demand for a front-printed structure in which a layer of ink or varnish is used as the outermost surface (top layer).

[0005] Generally, in packaging materials with a surface printing configuration, an overcoat varnish is applied to the surface of the ink coating to form a varnish layer (overcoat layer) for the purpose of protecting the ink coating. However, when a varnish layer is formed using a conventional solvent-based or water-based heat-drying overcoat varnish, it is difficult to obtain sufficient coating strength. Therefore, active energy ray-curable varnishes, which have strong coating properties, have been investigated.

[0006] When heat sealing is required for packaging applications, laminates having a layer composed of a heat-sealable material, such as a heat seal layer, are used. When a laminate having a heat seal layer is used as a packaging material with the above-mentioned surface-printed configuration, high temperatures of generally 150 to 180°C, and even around 250°C depending on the application, are applied to the ink or varnish coating that forms the outermost layer during the heat sealing process. Therefore, the ink or varnish coating that forms the outermost layer must have a higher level of heat resistance than is required for normal use. However, even when an active energy ray-curable ink or varnish is used to form the outermost layer of a packaging material, insufficient heat resistance can easily cause problems such as cracking or peeling in the ink or varnish coating. This creates a problem in that the design and specifications of the packaging material are limited by the physical properties of the coating that forms the outermost layer of the laminate.

[0007] In contrast, Patent Document 1 discloses a photopolymerizable resin composition for forming a printing layer in a packaging material, which contains a hydrogen abstraction photopolymerization initiator having a molecular weight of 220 or more and a melting point of 60°C or more, and a radical polymerizable compound. As seen in Patent Document 1, ultraviolet (UV) curable compositions are the mainstream of active energy ray-curable inks or varnishes used in packaging materials. However, ultraviolet (UV) curable compositions contain a certain amount or more of a photopolymerization initiator, which acts as an inert component and tends to reduce the strength and heat resistance of the cured coating film. Furthermore, when packaging materials are used in fields such as food, odors caused by decomposition products of the photopolymerization initiator are a major problem. Furthermore, when the composition is cured using ultraviolet light, damage to the substrate due to the heat generated by the lamp that generates the ultraviolet light is also a problem.

[0008] In this technical background, electron beam (EB) curable compositions that do not require a photopolymerization initiator, cause less thermal damage to a substrate, and can be cured with a high-energy electron beam have been attracting attention, particularly from the viewpoint of improving heat resistance and odor compared to ultraviolet (UV) curable compositions.

[0009] Japanese Patent Application Laid-Open No. 2007-204543

[0010] As described above, there is a need for a laminate having a surface-printed structure suitable for use in packaging materials, in which the outermost layer is formed using an electron beam-curable composition. Surface hardness is often used as an indicator of the heat resistance and strength of the outermost layer (also called the varnish layer) of a surface-printed laminate. However, when a laminate is used in packaging materials, many properties cannot be estimated by hardness alone, such as higher heat resistance required to prevent cracking or peeling of the varnish layer during heat sealing. For example, evaluation of brittleness in addition to hardness is also required.

[0011] For heat-sealing, the varnish layer of the laminate must not only be resistant to the applied heat (the heat resistance of the varnish layer itself), but also be able to suppress the effects of stress caused by heating. Specifically, the varnish layer must resist stress caused by deformation or shrinkage of the heat-seal layer due to heating, and stress caused by shrinkage of the substrate due to heating, thereby suppressing deformation of the heat-seal layer and the substrate. Therefore, the varnish layer of the laminate must be optimized in terms of both hardness and brittleness.

[0012] In addition, from the viewpoint of using the laminate as a packaging material, the varnish layer is required to have gloss, slip properties to withstand impact and friction during transportation, adhesion, etc. Furthermore, solvent resistance is also required to withstand alcohol disinfection, which is a recent measure against infectious diseases.

[0013] Therefore, in view of the above, the present invention provides a laminate having excellent heat resistance, gloss, slip properties, solvent resistance, and low odor, and a method for producing the same.

[0014] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, embodiments of the present invention include the following. However, the present invention is not limited to the following embodiments and includes various embodiments.

[0015] One embodiment of the present invention relates to a laminate having a substrate and a varnish layer provided on one surface of the substrate, wherein the varnish layer is a layer made of a cured product of an electron beam curable composition containing a (meth)acrylate compound, wherein the (meth)acrylate compound contains a compound having two or more (meth)acryloyl groups in its molecule, and the content of the compound having two or more (meth)acryloyl groups in its molecule is 80 mass% or more based on the total mass of the electron beam curable composition, wherein the electron beam curable composition is substantially free of a photopolymerization initiator, and wherein the varnish layer has a hardness of 100 to 180 MPa as measured by nanoindentation method and a recovery rate of 77 to 100% as measured by nanoindentation method.

[0016] One embodiment of the present invention relates to a packaging material formed using the laminate of the above embodiment.

[0017] One embodiment of the present invention relates to a method for producing the laminate of the above embodiment, comprising: applying an electron beam curable composition to one surface of a substrate to form a coating film; and irradiating the coating film with an electron beam to cure the coating film and form a varnish layer made of a cured product of the electron beam curable composition, wherein the electron beam irradiation conditions are an acceleration voltage of 50 to 200 kV and an exposure dose of 15 to 200 kGy.

[0018] According to the present invention, it is possible to provide a laminate that is excellent in heat resistance, gloss, slip property, solvent resistance, and low odor, and a method for producing the laminate.

[0019] Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention.

[0020] <1> Laminate One embodiment of the present invention relates to a laminate having a substrate and a varnish layer formed on one surface of the substrate. The varnish layer is composed of a cured product of an electron beam-curable composition containing a (meth)acrylate compound, and is characterized by a hardness of 100 to 180 MPa as measured by the nanoindentation method and a recovery rate of 77 to 100% as measured by the nanoindentation method. The electron beam-curable composition contains a compound having two or more (meth)acryloyl groups in its molecule as the (meth)acrylate compound, and the content of the compound having two or more (meth)acryloyl groups is 80% by mass or more based on the total mass of the electron beam-curable composition. The electron beam-curable composition is substantially free of photopolymerization initiators and is curable by irradiation with an electron beam.

[0021] The laminate of this embodiment may have other layers in addition to the substrate and the varnish layer formed on one side of the substrate and composed of a cured product of the electron beam curable composition. In some embodiments, the varnish layer preferably constitutes the outermost layer of the laminate. Since the varnish layer of the laminate of this embodiment is composed of a cured product of the electron beam curable composition, excellent coating properties can be easily obtained. Therefore, the laminate of this embodiment can be used in a variety of applications, and is particularly suitable for use as a packaging material.

[0022] From the viewpoint of using the laminate as a packaging material, the laminate preferably has a heat-sealable structure. As an example of a heat-sealable laminate, the laminate may further have a layer (heat-sealable layer) made of a heat-sealable material in addition to the substrate and the varnish layer. As another example, the laminate may have a substrate (called a heat-sealable substrate) made of a heat-sealable material and a varnish layer.

[0023] In some embodiments, the laminate preferably comprises a substrate, a varnish layer formed on one side of the substrate and made of a cured product of an electron beam-curable composition, and a heat seal layer provided on the other side of the substrate (the side opposite to the side on which the varnish layer is formed). That is, the laminate preferably comprises the heat seal layer, the substrate, and the varnish layer in this order.

[0024] Typically, heat sealing in the packaging field is performed by folding a packaging material (laminate) into a bag shape or placing the laminate on top of a container as a lid, and then heating only the edge of the laminate (the heat-sealed portion). Since only the edge of the heat-sealable layer or the heat-sealable substrate is actually heated during processing, the edge of the outermost layer of the laminate can also be composed of a heat-sealable layer or a heat-sealable substrate. For example, in a laminate having a substrate and a varnish layer in sequence, a varnish layer can be formed on the heat-sealable substrate except for the edge of the substrate, or a heat-sealable layer can be formed on the substrate and a varnish layer can be formed on the substrate except for the edge of the heat-sealable layer. In a laminate with such a configuration, the portion without the varnish layer (i.e., the edge of the heat-sealable substrate or the edge of the heat-sealable layer) partially constitutes the outermost layer of the laminate. In a laminate with such a configuration, a bag-shaped packaging material can be produced by folding the varnish layer so that the varnish layer is on the inside and then heat-sealing the edge of the laminate.

[0025] In some embodiments, the laminate may further include a printed layer between the substrate and the varnish layer. In this specification, the printed layer refers to a pattern such as letters or pictures formed using various inks. The configuration of the laminate will be described in more detail below.

[0026] <Substrate> In the laminate of this embodiment, the substrate is not particularly limited, and known substrates can be used. The substrate can be composed of plastic, metal, paper, or a combination of two or more of these materials, and is preferably in the form of a film or sheet. In some embodiments, a film substrate is preferred. For example, film substrates composed of plastic include polyolefin substrates such as polyethylene and polypropylene, polyester substrates such as polyethylene terephthalate and polylactic acid, polycarbonate substrates, polystyrene-based substrates such as polystyrene, AS resin, and ABS resin, nylon substrates, polyamide substrates, polyvinyl chloride substrates, polyvinylidene chloride substrates, and cellophane substrates. Other examples include paper substrates composed of paper, metal substrates composed of metal foil such as aluminum, and film substrates composed of composite materials thereof. Among these, polyolefin-based film substrates are preferred from the viewpoint of recyclability.

[0027] Alternatively, a vapor-deposited film substrate can be used, in which an inorganic compound such as silica, alumina, or aluminum is vapor-deposited onto the film substrate. Furthermore, the vapor-deposited surface may be coated with polyvinyl alcohol or the like. The substrate preferably has its printed surface (the surface in contact with the printing layer) treated for easy adhesion. Specific examples of such treatments include corona discharge treatment, ultraviolet / ozone treatment, plasma treatment, oxygen plasma treatment, and primer treatment. Furthermore, if sufficient adhesion cannot be obtained with a polyethylene terephthalate substrate, surface treatments such as acrylic coating treatment, polyester treatment, and polyvinylidene chloride treatment may be performed. Although not particularly limited, the thickness of the substrate may be preferably 3 to 50 μm, more preferably 8 to 40 μm, and even more preferably 10 to 30 μm.

[0028] A paper substrate may be used as the substrate. The paper substrate may be ordinary paper or cardboard, and the thickness is not particularly specified. The thickness of the paper substrate is, for example, 0.2 mm to 1.0 mm, 20 to 150 g / m ２The paper substrate may be one of the above, and the printing surface may be treated to facilitate adhesion. The paper substrate may be surface-deposited with a metal such as aluminum in order to impart design features. The paper substrate may also be surface-coated with acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resin, and may further be surface-treated by corona treatment or the like. Specific examples of surface-treated paper substrates include coated paper and art paper.

[0029] In some embodiments, when constructing a heat-sealable laminate, a heat-sealable substrate can be used as the substrate. Examples of heat-sealable substrates include substrates constructed using the sealant resin described below. More specifically, examples include film substrates such as unstretched polypropylene (CPP) and heat-sealable OPP (also known as HSOPP) having a melting point of 100 to 300°C. When using a heat-sealable substrate as the substrate, it is preferable to adjust the thickness of the substrate taking into account the resistance and hardness required for the application. While not particularly limited, the thickness of the substrate may be preferably 3 to 50 μm, more preferably 8 to 40 μm, and even more preferably 10 to 30 μm.

[0030] In some embodiments, when a laminate is constructed that further includes a heat-sealable layer in addition to the substrate and varnish layer, the substrate can be, for example, at least one plastic film substrate selected from the group consisting of polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and nylon (Ny). The polyethylene (PE) can be either low-density polyethylene (LLDPE) or high-density polyethylene (HDPE), with LLDPE being more preferred. The polypropylene (PP) can be either solid polypropylene (CPP) or biaxially oriented polypropylene (OPP). One of the above film substrates can be used alone, or two or more can be used in combination.

[0031] Furthermore, in some embodiments, a substrate (deposited film substrate) having a vapor-deposited film of a metal or inorganic compound other than a metal on the above film substrate may be used. In particular, a substrate having a vapor-deposited film (VM) of a metal such as aluminum can be preferably used from the viewpoint of easily obtaining excellent barrier properties in packaging materials. A specific example is a non-oriented polypropylene film (VMCPP) provided with a VM such as aluminum, and in particular, VMCPP using aluminum can be preferably used. Although not particularly limited, in some embodiments, the substrate may be at least one film substrate selected from the group consisting of LLDPE, Ny, CPP, OPP, and VMCPP.

[0032] <Varnish Layer> In the laminate of this embodiment, the varnish layer is composed of a cured product of an electron beam curable composition containing a (meth)acrylate compound, and is a layer obtained by irradiating a coating film of the electron beam curable composition with an electron beam to cure the coating film. In this specification, "(meth)acrylate compound" means a compound having a (meth)acryloyl group in the molecule. "(meth)acrylate" means acrylate and / or methacrylate (methacrylate). In addition, the term "(meth)acryloyl" means acryloyl and / or methacryloyl (methacryloyl).

[0033] In the laminate of this embodiment, the electron beam-curable composition constituting the varnish layer is not particularly limited, as long as the cured coating film satisfies the desired hardness and coating film recovery rate requirements. Although not particularly limited, the electron beam-curable compositions described below can be suitably used. In some embodiments, using an electron beam-curable composition containing 80% by mass or more of a (meth)acrylate compound based on the total mass of the composition tends to make it easier to obtain the desired physical properties of the coating film. The content of the (meth)acrylate compound in the electron beam-curable composition is preferably 80 to 99% by mass, more preferably 85 to 98% by mass, and particularly preferably 90 to 97% by mass, based on the total mass of the composition.

[0034] (Hardness of Varnish Layer) The varnish layer in the laminate of this embodiment has a hardness of 100 to 180 MPa as measured by the nanoindentation method. The hardness of the varnish layer may preferably be 120 to 170, more preferably 130 to 150. The hardness as measured by the nanoindentation method is the indentation hardness value measured using a micro-area mechanical property evaluation device (nanoindenter), and in this specification, it is the value measured using a Hysitron TI Premier (manufactured by Bruker). The nanoindenter indents only the very surface layer of the laminate, so it can measure the mechanical properties of only the thin varnish layer without being affected by the substrate. With other measurement methods, the indentation load and displacement are too large, making it difficult to measure only the thin layer. In this specification, the hardness of only the varnish layer is shown. Specific methods for measuring hardness using the nanoindentation method are as described in the Examples below.

[0035] (Varnish Layer Recovery Rate) The varnish layer in the laminate of this embodiment has a recovery rate of 77 to 100% as measured by the nanoindentation method. This recovery rate is preferably 80 to 100%, more preferably 85 to 100%. The nanoindentation recovery rate is a value that represents the recovery state of the coating film after indentation, measured using a nanoindenter, a micro-area mechanical property evaluation device. The values ​​described herein are values ​​measured using the same device as that used to measure the hardness of the varnish layer in the laminate. A higher number indicates a greater ability to absorb indentation and return to its original coating state; in this embodiment, this represents the brittleness of the coating film. A specific method for measuring the varnish layer recovery rate is as described in the Examples below. During heat-sealing of a heat-sealable laminate, a metal plate heated to 150°C or higher is typically pressed onto the laminate to thermocompress the desired areas. Therefore, during heat-sealing, the coating film is subjected to pressure (impact) from above in addition to heat. In contrast, in the laminate of this embodiment, the recovery rate of the varnish layer is within the above range, so that the coating film tends to recover easily from the impact during heat sealing.

[0036] In the laminate of this embodiment, the varnish layer is characterized by a nanoindentation hardness of 100 to 180 MPa and a nanoindentation recovery rate of 77 to 100%. Generally, the higher the hardness, the higher the crosslink density, and the greater the coating film's resistance. On the other hand, too high a hardness tends to make the coating more susceptible to cracking. Furthermore, even with the same hardness, the coating's susceptibility to cracking varies depending on the coating's recovery rate (brittleness). In contrast, in the laminate of this embodiment, the varnish layer meets the above-mentioned hardness and recovery rate requirements, respectively, thereby improving the coating's heat resistance during heat sealing and its resistance to impacts during heat sealing, thereby easily alleviating problems such as coating cracking or peeling. Thus, the laminate of this embodiment can achieve the high level of heat resistance required during heat sealing, and it goes without saying that sufficient heat resistance can be obtained even in normal usage.

[0037] <Heat Seal Layer> In the laminate of this embodiment, the heat seal layer is not particularly limited and can be formed using a heat-sealable material. For example, a material known in the art as a sealant resin can be used. Examples of sealant resins include polyethylenes 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)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and polyolefin resins such as ionomers. Among these, polypropylene-based resins are preferred from the viewpoint of recyclability, and unstretched polypropylene (CPP) is particularly preferred from the viewpoint of heat sealability.

[0038] To form the heat seal layer, these resins may be used as they are, or a sealant film in which the resin has been previously formed into a film may be used. The thickness of the heat seal layer is not particularly limited. For example, taking into consideration the processability and heat sealability of the laminate, the thickness is preferably in the range of 10 to 60 μm, more preferably in the range of 15 to 40 μm. The method for forming (laminating) the heat seal layer is not particularly limited. Examples include a method of thermally laminating an adhesive layer and a sealant film (thermal lamination, dry lamination), and a method of melting a sealant resin, extruding it onto the adhesive layer, cooling it to solidify it, and laminating it (extrusion lamination).

[0039] <Printed Layer> The laminate in this embodiment may further have a printed layer between the substrate and the varnish layer. The printed layer is obtained by printing ink to form a coating film, and drying or curing the coating film as necessary. As the ink, inks known in the art, such as solvent-based inks, water-based inks, and actinic ray-curable inks, can be used. In some embodiments, in consideration of the productivity of the laminate, actinic ray-curable inks are preferred. Among these, actinic ray-curable inks are preferred over electron beam-curable inks, and solventless electron beam-curable inks are particularly preferred. As a method for printing ink on the substrate (a method for forming a printed layer), known printing methods such as offset printing, gravure printing, flexographic printing, and inkjet printing can be selected.

[0040] Although not particularly limited, preferred configuration examples of the laminate of this embodiment include substrate (PE) / varnish layer, substrate (CPP) / varnish layer, substrate (PET) / varnish layer, substrate (CPP / PET) / varnish layer, substrate (LLDPE / Ny) / varnish layer, substrate (VMCPP) / varnish layer, and substrate (VMCPP / OPP) / varnish layer. Other preferred configuration examples of the laminate of this embodiment include substrate (PE) / printed layer / varnish layer, substrate (CPP) / printed layer / varnish layer, substrate (PET) / printed layer / varnish layer, substrate (CPP / PET) / printed layer / varnish layer, substrate (LLDPE / Ny) / printed layer / varnish layer, substrate (VMCPP) / printed layer / varnish layer, and substrate (VMCPP / OPP) / printed layer / varnish layer.

[0041] In some embodiments, an example of a laminate having a heat-sealable structure is a structure in which a heat-sealable layer is provided on the other side of the substrate of the laminate exemplified above. For example, the laminate may have a heat-sealable layer / substrate / varnish layer structure, and may further have a printed layer between the substrate and the varnish layer. Another example is a laminate using a heat-sealable substrate such as HSOPP as the substrate of the laminate exemplified above. In this case, the laminate may have a heat-sealable substrate / varnish layer structure, and may further have a printed layer between the substrate and the varnish layer.

[0042] The laminate of this embodiment can be suitably used as a packaging material. Various types of packaging materials can be constructed using the laminate of this embodiment. For example, a heat-sealable laminate can be processed into a shape such as a lid for a container, or a bag-like shape such as a pouch, to provide a packaging material. It can also be processed into a shape such as a clear file folder. For example, a clear file folder can be produced by folding the laminate and crimping one of the edges following the fold (the part that will become the bottom of the clear file) with ultrasound or the like. As yet another example, the laminate can be used in its original shape as a packaging material such as a packaging film.

[0043] <2> Electron beam curable composition One embodiment of the present invention relates to an electron beam curable composition (also referred to as a varnish layer forming composition) that can be suitably used as a material for forming the varnish layer in the laminate of the above embodiment.

[0044] The electron beam curable composition of this embodiment contains a (meth)acrylate compound. In this specification, a (meth)acrylate compound refers to a compound having a (meth)acryloyl group in the molecule. Based on the total mass of the electron beam curable composition, the content of the (meth)acrylate compound is preferably 80 mass% or more. The content of the (meth)acrylate compound is preferably 80 to 99 mass%, more preferably 85 to 98 mass%, and particularly preferably 90 to 97 mass%, of the total amount of the composition.

[0045] Specific examples of the (meth)acrylate compound that can be used to form the electron beam curable composition of this embodiment 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, and polyethylene glycol (600) di(meth)acrylate. Examples of the difunctional (meth)acrylate compound include difunctional (meth)acrylate compounds such as hydroxypivalic acid neopentyl glycol 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, dicyclopentanyl di(meth)acrylate, and tris(2-hydroxyethyl)isocyanurate di(meth)acrylate. In this specification, "PO" represents propylene oxide, and "EO" represents ethylene oxide.Further examples include trifunctional (meth)acrylate compounds such as trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, glycerin propoxy triacrylate, 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; and hexafunctional (meth)acrylate compounds such as dipentaerythritol hexa(meth)acrylate.

[0046] As the (meth)acrylate compound, urethane acrylates such as aliphatic urethane acrylates and aromatic urethane acrylates, polyester acrylates, polyether acrylates, epoxy acrylates, etc. can be used.

[0047] The (meth)acrylate compounds may be used alone or in combination of two or more.

[0048] From the viewpoint of curability, the (meth)acrylate compound preferably contains a polyfunctional acrylate having two or more (meth)acryloyl groups in the molecule. Based on the total mass of the electron beam-curable composition, the content of the polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in the molecule is preferably 80 mass% or more. The content of the (meth)acrylate compound is preferably 80 to 99 mass%, more preferably 85 to 98 mass%, and particularly preferably 90 to 97 mass%.

[0049] In some embodiments, the polyfunctional (meth)acrylate is preferably a (meth)acrylate compound having three or more (meth)acryloyl groups in the molecule. Based on the total mass of the polyfunctional acrylate, the content of the (meth)acrylate compound having three or more groups in the molecule may be 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. In some embodiments, the content may be preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the polyfunctional acrylate.

[0050] From the viewpoint of heat resistance, the (meth)acrylate compound preferably contains alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate. By containing alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate, the hardness and recovery rate of the varnish layer are improved, and the heat resistance of the laminate is improved. More preferably, the alkylene oxide modification amount of the alkylene oxide-modified trimethylolpropane triacrylate is 3 to 6 mol / mol.

[0051] 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, it may be ethylene oxide-modified (3 to 6 mol / mol) trimethylolpropane triacrylate or propylene oxide-modified (3 to 6 mol / mol) trimethylolpropane triacrylate. In some embodiments, ethylene oxide-modified (3 mol / mol) trimethylolpropane triacrylate or propylene oxide-modified (3 mol / mol) trimethylolpropane triacrylate is particularly preferred. The content of the alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate is preferably 20 to 90 mass% based on the total mass of the electron beam-curable composition. In some embodiments, the content may be preferably 50 to 90% by mass, more preferably 60 to 90% by mass, and even more preferably 70 to 85% by mass.

[0052] Furthermore, from the viewpoint of heat resistance, the (meth)acrylate compound preferably contains dipentaerythritol hexaacrylate. The inclusion of dipentaerythritol hexaacrylate improves the hardness of the varnish layer and improves the heat resistance of the laminate. When dipentaerythritol hexaacrylate is contained, it is preferably present in an amount of 5 to 50 mass% based on the total mass of the electron beam-curable composition.

[0053] Furthermore, from the viewpoint of gloss, the (meth)acrylate compound preferably contains tripropylene glycol diacrylate. By including tripropylene glycol diacrylate, the gloss of the laminate is improved. When tripropylene glycol diacrylate is included, it is preferably contained in an amount of 5 to 50 mass %, more preferably 5 to 30 mass %, and even more preferably 9 to 20 mass %, based on the total mass of the electron beam curable composition.

[0054] The electron beam curable composition of this embodiment may further contain an extender pigment, resin fine particles, and a leveling agent.

[0055] <Extender Pigment> The electron beam curable composition of this embodiment preferably further contains a body pigment. The inclusion of a body pigment enhances the film-forming properties of the coating film and improves slip resistance. Specific examples of the body pigment include silica, barium sulfate, alumina white, calcium carbonate, magnesium carbonate, aluminum silicate, magnesium silicate, silicon dioxide, and aluminum hydroxide. These may be used alone or in combination of two or more. Silica is preferred as the body pigment. The content of the body pigment is preferably 0.1 to 10 mass %, and more preferably 1.0 to 5 mass %, based on the total mass of the electron beam curable composition.

[0056] <Resin Particles> The electron beam curable composition of this embodiment preferably further contains resin particles, which improves slip properties and heat resistance.

[0057] Specific examples of resin particles include urethane resin particles, acrylic resin particles, acrylic-styrene copolymer resin particles, polycarbonate resin particles, polyethylene resin particles, polystyrene resin particles, silicone resin particles, melamine resin particles, melamine-benzoguanamine resin particles, melamine-benzoguanamine-formaldehyde resin (condensate) particles, polypropylene resin particles, amide resin particles, polytetrafluoroethylene resin particles, and benzoguanamine resin particles. These may be used alone or in combination of two or more, if necessary.

[0058] From the viewpoints of slip property, heat resistance, and gloss, the content of the resin fine particles is preferably 0.1 to 5 mass %, more preferably 0.25 to 3 mass %, based on the total mass of the electron beam curable composition.

[0059] The resin microparticles may be commercially available or may be produced by known production methods. Specific examples of urethane resin microparticles 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, all manufactured by Negami Chemical Industrial Co., Ltd. Furthermore, the urethane resin microparticles may have a crosslinked structure. Specific examples of urethane resin microparticles having a crosslinked structure include crosslinked urethane resin microparticles such as Art Pearl JB-800T, Art Pearl JB-600T, Art Pearl P-800T, and Art Pearl P-400T, all manufactured by Negami Chemical Industrial Co., Ltd.

[0060] Examples of acrylic resin fine particles include Art Pearl J4PY and Art Pearl J5PY manufactured by Negami Chemical Industrial Co., Ltd., and Ganz Pearl GB08S manufactured by Aica Kogyo Co., Ltd. Other examples include Eposter MA1002, Eposter MA1004, Eposter MA1006, and Eposter MA1010 manufactured by Nippon Shokubai Co., Ltd., Tuftic FH-S005, Tuftic FH-S008, Tuftic FH-S010, Tuftic FH-S015, and Tuftic 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, and MX-3000 manufactured by Soken Chemical & Engineering Co., Ltd.

[0061] Specific examples of acrylic-styrene copolymer resin particles include Eposter MA2003 manufactured by Nippon Shokubai Co., Ltd., and FS-102, FS-201, FS-301, MG-451, and MG-351 manufactured by Nippon Paint Industrial Coatings Co., Ltd.

[0062] Specific examples of polycarbonate resin fine particles include fine particles described in JP-A-2014-125495, fine particles obtained by the manufacturing method described in JP-A-2011-26471, and fine particles obtained by the method described in JP-A-2001-213970.

[0063] Specific examples of silicone resin microparticles include KMP-594, KMP-597, KMP-598, KMP-600, KMP-601, and KMP-602 manufactured by Shin-Etsu Chemical Co., Ltd., Trefil E-506S and EP-9215 manufactured by Dow Corning Toray Co., Ltd., and the Tosulpearl series manufactured by Momentive.

[0064] Specific examples of polyethylene resin fine particles include Mipelon XM-220 and XM221U manufactured by Mitsui Chemicals, Inc., Flowbeads LE-1080 manufactured by Sumitomo Seika Chemicals Co., Ltd., and Cerafluor 991 manufactured by BYK Japan KK.

[0065] Specific examples of polystyrene-based fine particles include Chemisnow SX-130H, SX-350H, and SX-500H manufactured by Soken Chemical & Engineering Co., Ltd.

[0066] Specific examples of melamine resin fine particles include Eposter SS, Eposter S, Eposter FS, Eposter S6, and Eposter S12 manufactured by Nippon Shokubai Co., Ltd.

[0067] A specific example of the melamine-benzoguanamine resin fine particles is Eposter M30 manufactured by Nippon Shokubai Co., Ltd.

[0068] Specific examples of benzoguanamine resin fine particles include Eposter MS, Eposter M05, and Eposter L15 manufactured by Nippon Shokubai Co., Ltd.

[0069] A specific example of polytetrafluoroethylene resin fine particles is SST-3T1-RC manufactured by Shamrock Technologies.

[0070] The resin microparticles are preferably one or more selected from the group consisting of silicone resin microparticles, acrylic resin microparticles, polytetrafluoroethylene resin microparticles, and polyethylene resin microparticles, and more preferably one or more selected from the group consisting of acrylic resin microparticles and polytetrafluoroethylene microparticles. When silicone resin microparticles, acrylic resin microparticles, or polyethylene resin microparticles are used, particle size control is easy, high sphericity, and excellent dispersibility can be easily achieved. Furthermore, these resin microparticles are highly transparent and can achieve good slip properties while minimizing gloss loss. When polytetrafluoroethylene resin microparticles are used, excellent heat resistance and slip properties can be achieved due to their chemical stability, high melting point, and low coefficient of friction.

[0071] From the viewpoints of slip property, heat resistance, and gloss, it is preferable to use resin fine particles having an average particle size of 2 to 12 μm, more preferably 5 to 10 μm. The resin fine particles may be in the form of particles composed of various resins or particles whose surfaces are coated with various resins. Furthermore, the resin fine particles may be used alone or in combination of two or more types.

[0072] <Leveling Agent> The electron beam curable composition of this embodiment preferably further contains a leveling agent. By including a leveling agent, slip properties are improved. From the viewpoint of surface slip properties, the leveling agent preferably contains a silicone-modified acrylate compound. Furthermore, one type of leveling agent may be used alone, or two or more types may be used in combination. The content of the leveling agent is preferably 0.1 to 3 mass %, more preferably 0.4 to 1.5 mass %, and even more preferably 0.4 to 1.0 mass %, based on the total mass of the electron beam curable composition.

[0073] <Other Components> Various additives may be added to the electron beam-curable composition of the present embodiment as needed, as long as the effects of the present invention are not impaired. For example, additives that can be used include antistatic agents, surfactants, antifoaming agents, ultraviolet absorbers, antioxidants, curing agents, plasticizers, wetting agents, adhesion aids, antifoaming agents, antistatic agents, trapping agents, antiblocking agents, and preservatives.

[0074] The electron beam curable composition of this embodiment is substantially free of photopolymerization initiators. In this specification, "substantially free" means that the photopolymerization initiator is not intentionally added and the content due to unintentional addition is less than 1 mass%. Unintentional addition includes trace amounts of the photopolymerization initiator in each raw material, contamination during the production process of the composition or the production process of the printed matter, etc.

[0075] Furthermore, the electron beam-curable composition of this embodiment is substantially free of organic solvents. There is concern that organic solvents used as viscosity modifiers in printing inks may contain MOSH / MOAH, which are persistent organic pollutants. Furthermore, since the absence of volatile components (non-VOC) is expected to reduce the environmental impact and improve work safety, it is preferable that the composition of this embodiment be substantially free of organic solvents.

[0076] In some embodiments, the (meth)acrylate compound (A) contained in the electron beam-curable composition may be at least one selected from the group consisting of alkylene oxide-modified trimethylolpropane triacrylate (A1) and (A2) (meth)acrylate compounds other than (A1). In some embodiments, the (meth)acrylate compound (A) may be a combination of (A1) and (A2), where (A2) includes at least one selected from the group consisting of dipentaerythritol hexaacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate. In the above embodiments, the (meth)acrylate compound (A) preferably includes the alkylene oxide-modified trimethylolpropane triacrylate (A1), and (A2) includes dipentaerythritol hexaacrylate and tripropylene glycol diacrylate.

[0077] In another embodiment, the (meth)acrylate compound (A) is composed solely of the (A2), and the (A2) preferably includes two or more compounds selected from the group consisting of dipentaerythritol hexaacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate. In the above embodiment, the (A2) is preferably a combination of dipentaerythritol hexaacrylate / tripropylene glycol diacrylate, or dipentaerythritol hexaacrylate / tripropylene glycol diacrylate / trimethylolpropane triacrylate.

[0078] The electron beam-curable composition of this embodiment may further contain, as necessary, a component that does not affect the curing of the coating film, in addition to the (meth)acrylate compound (A) configured as described above. In some embodiments, the electron beam-curable composition may further contain, in addition to the (meth)acrylate compound (A) configured as described above, at least one selected from the group consisting of an extender pigment, a resin fine particle, and a leveling agent.

[0079] <Method for Producing Electron Beam-Curable Composition> The electron beam-curable composition of this embodiment can be produced by mixing and stirring a (meth)acrylate compound and other components, such as resin fine particles, which are used as needed, for about 30 minutes to 3 hours using a mixer, etc. Note that the (meth)acrylate compound may be produced by mixing and stirring two or more types of (meth)acrylate compounds in advance, and then adding other components, such as resin fine particles, which are used as needed.

[0080] <3> Manufacturing Method of Laminate One embodiment of the present invention relates to a manufacturing method of the laminate of the above embodiment. The manufacturing method of this embodiment includes: applying an electron beam curable composition to one surface of a substrate to form a coating film; and irradiating the coating film with an electron beam to cure the coating film and form a varnish layer made of a cured product of the electron beam curable composition, wherein the electron beam irradiation conditions are an acceleration voltage of 50 to 200 kV and an exposure dose of 15 to 200 kGy.

[0081] The method for manufacturing a laminate of this embodiment includes a step for forming at least a varnish layer on a substrate. The method for manufacturing a laminate of this embodiment may include other steps in addition to the step of forming the varnish layer, as necessary. In some embodiments, a step of forming a printing layer may be included, preferably prior to forming the varnish layer on the substrate. Furthermore, a step of forming a heat seal layer on the other side of the substrate may be included.

[0082] <Formation of Varnish Layer> The step of forming the varnish layer can be carried out according to a method well known in the art. For example, it may include forming a coating film of the composition on one side of the substrate and then curing the coating film. Methods 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., offset printing (normal lithographic printing using dampening water and waterless lithographic printing not using dampening water), flexographic printing, gravure printing, screen printing, etc. Furthermore, in inline printing and offline printing, various inks such as UV curable, electron beam curable, thermal drying, evaporation drying, oxidative polymerization, penetration drying, thermal polymerization, two-component curable, liquid toner, and powder toner inks may be used in combination, as needed.

[0083] <Electron Beam Irradiation Conditions> After forming a coating film on a substrate using the electron beam-curable composition of this embodiment using various printing methods, the coating film is cured by irradiating it with electron beams from an electron beam irradiator to form a varnish layer. The electron beam irradiation conditions for curing the coating film are preferably adjusted taking into consideration the balance between damage to the substrate, such as a film substrate, and the curability of the electron beam-curable composition. In some embodiments, the acceleration voltage is preferably 50 to 200 kV, more preferably 80 to 110 kV. Meanwhile, the irradiation dose is preferably 15 to 60 kGy, more preferably 20 to 45 kGy. An irradiation dose of 15 to 60 kGy provides sufficient coating strength and easily suppresses problems associated with substrate damage, such as a decrease in substrate strength, odor, and yellowing.

[0084] When producing a laminate having a printed layer, ink is applied prior to application of an electron beam-curable composition to form a varnish layer. As the ink, inks known in the art, such as solvent-based inks, water-based inks, and actinic ray-curable inks, can be used, and the printing method can be selected depending on the type of ink. Known printing methods, such as offset printing, gravure printing, flexographic printing, and inkjet printing, can be selected. While not particularly limited, the various inks used in the examples described below can be suitably used. For example, electron beam (EB)-curable inks contain a (meth)acrylate compound and a pigment. Gravure printing inks contain a binder resin containing a polyurethane resin, a pigment, and a solvent. Ultraviolet (UV)-curable inks contain a binder resin containing a rosin resin, a (meth)acrylate compound, an initiator, and a pigment. Water-based flexographic printing inks contain a binder resin containing an aqueous polyurethane resin, a solvent containing water and alcohol, and a pigment. The various inks may further contain various additives as required.

[0085] For example, when an electron beam curable ink is used to form a printing layer, the ink is applied to a substrate to form a coating film, and then an electron beam curable composition (varnish) is applied (wet-on-wet). Electron beams are then irradiated to simultaneously cure the ink coating and the varnish coating, forming a printing layer and a varnish layer. When an ink other than an electron beam curable ink is used, the ink is applied to a substrate to form a coating film, and then the coating film is dried or cured to form a printing layer. Subsequently, an electron beam curable composition (varnish) is applied to the printing layer, and then electron beams are irradiated to cure the coating film, forming a varnish layer.

[0086] When manufacturing a laminate having a heat seal layer, either a method of laminating a heat seal layer after preparing a base material having a varnish layer, or a method of forming a varnish layer on a base material having a heat seal layer may be used. Here, the electron beam irradiated when forming the varnish layer may affect the heat seal layer depending on the intensity of the electron beam, the type and thickness of the base material, and the heat seal strength may be reduced. When applying the method of laminating a heat seal layer after preparing a base material having a varnish layer, a laminate can be manufactured without being affected by the electron beam as described above.

[0087] Representative embodiments of the present invention are described below. <1> A laminate having, in this order, a heat seal layer, a substrate, and a varnish layer, 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 mass % or more of a compound having two or more (meth)acryloyl groups in the molecule based on the total amount of the electron beam-curable composition, the electron beam-curable composition is substantially free of a photopolymerization initiator, and the varnish layer has a hardness of 100 to 180 MPa as measured by the nanoindentation method and a recovery rate of 77 to 100% as measured by the nanoindentation method.

[0088] <2> The laminate according to <1> above, further comprising a printed layer between the substrate and the varnish layer.

[0089] <3> The laminate according to <1> or <2> above, wherein the (meth)acrylate compound contains alkylene oxide-modified (3 to 9 mol / mol) trimethylolpropane triacrylate.

[0090] <4> The laminate according to any one of <1> to <3> above, wherein the electron beam curable composition further contains an extender pigment.

[0091] <5> The laminate according to any one of <1> to <4> above, wherein the electron beam curable composition further contains resin fine particles.

[0092] <6> The laminate according to any one of the above <1> to <5>, wherein the electron beam curable composition further contains a leveling agent.

[0093] <7> A packaging material comprising the laminate according to any one of <1> to <6> above.

[0094] <8> The method for producing a laminate according to any one of the above items <1> to <6>, wherein the conditions for curing with electron beams are an acceleration voltage of 50 to 200 kV and an exposure dose of 15 to 200 kGy.

[0095] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2023-198150, filed November 22, 2023, the entire disclosure of which is incorporated herein by reference.

[0096] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these. In the examples and comparative examples, "parts" means "parts by mass" and "%" means "% by mass."

[0097] <1> Electron beam curable composition (varnish layer forming composition) <1-1> Various materials Details of the materials used in the production examples, examples and comparative examples described below are as follows. <(Meth)acrylate Compound (A)> (Alkylene oxide-modified trimethylolpropane triacrylate (A1)) Miramer M3130: manufactured by MIWON Corporation, TMP(EO)3TA (EO (3 mol)-modified trimethylolpropane triacrylate) Miramer M3160: manufactured by MIWON Corporation, TMP(EO)6TA (EO (6 mol)-modified trimethylolpropane triacrylate) Miramer M3190: manufactured by MIWON Corporation, TMP(EO)9TA (EO (9 mol)-modified trimethylolpropane triacrylate) Miramer M3150: manufactured by MIWON Corporation, TMP(EO)15TA (EO (15 mol)-modified trimethylolpropane triacrylate) Etermer EM2381: TMP(PO)3TA (PO (3 mol) modified trimethylolpropane triacrylate) manufactured by Eternal Materials. A-TMPT-6PO: TMP(PO)6TA (PO (6 mol) modified trimethylolpropane triacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd.

[0098] (Other (meth)acrylates (A2)) Miramer M600: manufactured by MIWON Corporation, DPHA (dipentaerythritol hexaacrylate) TPGDA: manufactured by Daicel-Allnex Corporation, TPGDA (tripropylene glycol diacrylate) Miramer M300: manufactured by MIWON Corporation, TMPTA (trimethylolpropane triacrylate) Miramer M122: manufactured by MIWON Corporation, LA (lauryl acrylate) EBECRYL 130: manufactured by Daicel-Allnex Corporation, TCDDA (tricyclodecane diacrylate) PETA: manufactured by Daicel-Allnex Corporation, pentaerythritol tetraacrylate EBECRYL 50: EO (5 mol) modified pentaerythritol tetraacrylate manufactured by Daicel Allnex Co., Ltd. M-215: EO-modified isocyanuric acid diacrylate manufactured by Toagosei Co., Ltd. <Resins> DAP-A: Diallyl phthalate resin manufactured by Osaka Soda Co., Ltd.

[0099] <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) <Resin particles> Sekisui Techpolymer BM30X-5: Sekisui Plastics Co., Ltd., average particle size 5 μm, acrylic resin particles <Leveling agent> TEGO Rad2300: Evonik, polyether-modified polydimethylsiloxane resin having an acryloyl group <Photopolymerization initiator> OMNIRAD 1173: IGM Resins, 2-hydroxy-2-methylpropiophenone

[0100] <1-2> Production examples of electron beam curable compositions (varnish layer forming compositions) (Production Example 1) As shown in Table 1, 76.0 parts of Miramer M3130, 10.0 parts of TPGDA, 10.0 parts of Miramer M600, 0.5 parts of Sekisui Techpolymer BM30X-5, 0.5 parts of TEGORad 2300, and 3.0 parts of AEROSILR972 were mixed in a blending ratio and stirred using a rotation / revolution mixer to obtain an electron beam curable composition.

[0101] (Production Examples 2 to 25) Electron beam curable compositions of Production Examples 2 to 25 were obtained in the same manner as in Example 1, except that materials were used according to the compositions shown in Table 1.

[0102] <2> Ink for forming printing layer <2-1> Various materials <Binder resin> EBECRYL 8411: Aliphatic urethane acrylate manufactured by Daicel-Allnex Corporation Miramer M122: LA (lauryl acrylate) manufactured by MIWON Corporation TPGDA: TPGDA (tripropylene glycol diacrylate) manufactured by Daicel-Allnex Corporation Laromer LR 8863: TMP(EO)3TA (EO (3 mol) modified trimethylolpropane triacrylate) manufactured by BASF Corporation SR355NS: Ditrimethylolpropane tetraacrylate manufactured by Arkema <Pigment> MOGAL E: Pigment manufactured by Bilra Carbon <Dispersant> Solsperse 32000: Dispersant manufactured by Lubrizol <Antifoaming agent> BYK-1790: Antifoaming agent manufactured by BYK

[0103] <2-2> Production Examples of Inks for Forming Printing Layer (Production Example A) Ink A (EB-curable ink) 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 Solsperse 32000, and 0.5 parts of BYK-1790 were mixed in a blending ratio and milled using a triple roll mill to prepare electron beam-curable flexographic ink A.

[0104] <3> Examples of Laminate Production The hardness and recovery rate of the varnish layer of the laminates produced in the following Examples and Comparative Examples were measured according to the methods described below.

[0105] (Hardness of Varnish Layer) The hardness of the varnish layer measured by the nanoindentation method is the value of indentation hardness (H) measured using a micro-area mechanical property evaluation device (nanoindenter). Specifically, the measurement of the indentation hardness (H) of the varnish layer was carried out as follows. A triangular pyramidal Berkovich indenter was used as the indenter of the nanoindenter. First, the Berkovich indenter was pressed into the measurement sample under the indentation conditions described below, and the indentation depth h (nm) relative to the indentation load F (μN) was continuously measured to create a load-displacement curve. The maximum indentation load Fmax (μN) was determined from the created load-displacement curve. Next, the maximum indentation load Fmax (μN) was calculated as the contact projected area Ac (μm ２ The hardness was calculated by dividing the contact area by the contact depth h (nm). In other words, H = Fmax / Ac. Here, Ac is the contact projected area corrected for the indenter tip curvature using a standard sample of fused quartz using the standard method for the instrument. The contact projected area "Ac" was calculated from the contact depth h (nm), and Ac = 24.56h ２ The indentation conditions were as follows: at room temperature (25°C), the indenter was first pressed to a depth of 300 nm in 5 seconds (i.e., 60 nm / s), then held at the depth of 300 nm for 2 seconds, and finally unloaded to 0 nm in 5 seconds.

[0106] (Varnish Layer Recovery Rate) The recovery rate (%) is an index showing the degree of recovery of a coating film (varnish layer) indented by horizontal movement of an indenter. Specifically, the varnish layer recovery rate was measured as follows. A conical indenter with a conical shape was used as the indenter of the nanoindenter. First, the conical indenter was driven horizontally on the measurement sample under the indentation conditions described below, and the indentation depth h (nm) versus horizontal movement distance (μm) was continuously measured to create a horizontal distance-vertical displacement curve. The recovery rate (%) was calculated from the created horizontal distance-vertical displacement curve. The indentation conditions were as follows: at room temperature (25°C), the conical indenter was moved horizontally for 6 μm at 0.4 μm / s, and a maximum load of 300 μN was applied vertically at a loading rate of 20 μN / s. After measurement, the indentation depth was measured by tracing the same location on the measurement sample with a weak load that did not cause deformation. From the measurement data obtained as described above, the recovery rate (%) was calculated using the following formula: Recovery rate (%) = (max vertical displacement during indentation (nm) - max indentation depth after indentation (nm)) / max vertical displacement during indentation (nm) × 100

[0107] Example 1 The electron beam curable composition 1 (varnish layer forming composition 1) obtained in Production Example 1 was used to print on a substrate by flexographic printing. The printed coating was immediately irradiated with an electron beam to form a cured coating, thereby producing a laminate. More details are as follows. The printing machine used was a Flexiproof 100 manufactured by RK PrintCoat Instruments. The printing conditions were a printing speed of 60 m / min, an anilox roll ruling of 300 lines / inch, and an anilox roll cell capacity of 13.09 cm. ３ / m ２ The engraving pattern on the anilox roll was hexagonal. The printing plate used was an ESXQ manufactured by DuPont, and the area of ​​the printing plate was 106.8 cm. ２ The amount of the electron beam curable composition applied was 2.5 to 3.5 g / m after curing. ２The printed result was as follows. Electron beam irradiation was performed using an electron beam irradiator EC250 / 15 / 180L manufactured by Iwasaki Electric Co., Ltd., under conditions of an acceleration voltage of 110 kV and an electron dose of 30 kGy. The substrate used was a laminate substrate S1 (CPP / OPP) made of a biaxially oriented polypropylene film (OPP) and an unoriented polypropylene film (CPP). The laminate substrate S1 was prepared by the method described below. A varnish layer-forming composition 1 was printed on the biaxially oriented polypropylene film (OPP) side of the laminate substrate S1 to form a varnish layer. The hardness and recovery rate of the varnish layer for the laminate (substrate S1 (CPP / OPP) / varnish layer) obtained as described above were measured according to the method described above. The results are shown in Table 1.

[0108] (Method of producing laminated substrate S1) A diluted adhesive solution was applied to a biaxially oriented polypropylene film (product name: FOR-BT, thickness 20 μm) manufactured by Futamura Chemical Co., Ltd., and the solvent was evaporated. The diluted adhesive solution 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 60%. The diluted adhesive solution was applied at room temperature using a bar coater, with the solid coating amount after solvent evaporation being 2.0 to 2.5 g / m ２ Next, the adhesive-coated surface of the film was bonded to a non-stretched polypropylene film (FHK 30 μm, manufactured by Futamura Chemical Co., Ltd.). Then, the film was left for 24 hours in an environment of 35°C and humidity 60% RT to 80% RT to obtain a laminated substrate S1.

[0109] (Examples 2 to 14) The varnish layer-forming composition 1 used in Example 1 was changed as shown in Table 1. All other changes were made in the same manner as in Example 1 to obtain laminates (substrate S1 (CPP / OPP) / varnish layer) for Examples 2 to 14. The hardness and recovery rate of the varnish layer of the laminates obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0110] (Example 15) The electron beam irradiation conditions (acceleration voltage 110 kV, electron beam dose 30 kGy) used in Example 1 to form the varnish layer (cured coating film) were changed to 60 kGy. Otherwise, a laminate (substrate S1 (CPP / OPP) / varnish layer) was produced in the same manner as in Example 1. The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0111] (Example 16) The electron beam irradiation conditions (acceleration voltage 110 kV, electron beam dose 30 kGy) used in Example 1 to form the varnish layer (cured coating film) were changed to 200 kV. Otherwise, a laminate (substrate S1 (CPP / OPP) / varnish layer) was produced in the same manner as in Example 1. The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0112] (Examples 17 to 19) The varnish layer-forming composition 1 used in Example 1 was changed as shown in Table 1. All other changes were made in the same manner as in Example 1 to produce a laminate (substrate S1 (CPP / OPP) / varnish layer). The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0113] (Examples 20 to 25) The substrate S1 used in Example 1 was changed to the substrates S2 to S8 below. Otherwise, the same procedure as in Example 1 was followed, and varnish layer-forming composition 1 was printed on the substrate. Furthermore, electron beams were irradiated under the same conditions as in Example 1 to harden the coating film formed by the printing, forming a varnish layer, and a laminate (substrate / varnish layer) was produced. The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1. The configurations of the laminates obtained in Examples 20 to 26 are as follows: Example 20: Substrate S2 (PE) / varnish layer Example 21: Substrate S3 (PET) / varnish layer Example 22: Substrate S4 (CPP / PET) / varnish layer Example 23: Substrate S5 (LLDPE / Ny) / varnish layer Example 24: Substrate S6 (CPP) / varnish layer Example 25: Substrate S7 (HSOPP) / varnish layer Example 26: Substrate S8 (VMCPP / OPP) / varnish layer

[0114] (Example 27) In the same manner as in Example 1, the EB-curable ink A prepared in Production Example A was printed on the substrate S1 using a flexographic printing method to form an ink coating film, in the same manner as in Example 1, and the varnish layer-forming composition 1 was then printed on top of the ink coating using a flexographic printing method, in the same manner as in Example 1, and the ink coating film and varnish coating film were simultaneously cured by irradiating with an electron beam to produce a laminate (substrate S1 (CPP / OPP) / printed layer / varnish layer). The electron beam irradiation conditions were 110 kV and 30 kGy. The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0115] (Example 28) Using a gravure five-color press (Fuji Machinery five-color press) equipped with a gravure plate with a plate depth of 20 μm, gravure ink (Rio Alpha R92 Ink (manufactured by Toyo Ink Co., Ltd.)) was printed on the substrate S1 to form an ink coating film, and then the ink coating film was dried to produce a substrate with a printed layer. The ink printing was carried out at a printing speed of 150 m / min, and the ink coating film was dried at a temperature of 50 ° C. Next, a varnish layer was formed on the printed surface of the substrate with the printed layer obtained as described above using a varnish layer-forming composition in the same manner as in Example 1, to produce a laminate (substrate S1 (CPP / OPP) / printed layer / varnish layer). The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0116] Example 29 Aqueous flexographic ink "HW 688AQ series" (manufactured by Toyo Ink Co., Ltd.) was adjusted with water to a viscosity of 25 seconds using a Zahn Cup #4 (manufactured by Rigo Co., Ltd.). The ink was printed on the substrate S1 by flexographic printing in the same manner as in Example 1 for printing the varnish layer-forming composition to form an ink coating film, and the ink coating film was then dried to produce a substrate having a printed layer. Printing was carried out using a 4.3 cm cell. ３ / m ２The test was carried out using a plate with a line count of 260 lines / cm. The ink coating was dried at a temperature of 70°C. Next, a varnish layer was formed on the printed surface of the substrate having the printed layer obtained as described above using a varnish layer-forming composition in the same manner as in Example 1, to produce a laminate (substrate S1 (CPP / OPP) / printed layer / varnish layer). The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0117] (Example 30) Using a simple color developer RI tester, a UV-curable ink (FD Karton X Ink M (manufactured by Toyo Ink Co., Ltd.) was printed on a substrate S1 so that the film thickness was 1.0 μm to form an ink coating film, and then the ink coating film was irradiated with ultraviolet light to form a cured coating film, thereby producing a substrate having a printed layer. The ultraviolet light irradiation was performed using one high-pressure mercury lamp with an integrated light amount of 100 mJ / cm. ２ The test was carried out under the following conditions. Next, a varnish layer was formed on the printed surface of the substrate having the printed layer obtained as described above using a varnish layer-forming composition in the same manner as in Example 1, to produce a laminate (substrate S1 (CPP / OPP) / printed layer / varnish layer). The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0118] (Example 31) Using a simple color developer RI tester, an EB-curable ink (FD EB AD Ink M (manufactured by Toyo Ink Co., Ltd.) was printed to a film thickness of 1.0 μm to form an ink coating. Next, varnish layer-forming composition 1 was printed on top of the ink coating using the flexographic printing method in the same manner as in Example 1 to form a varnish coating. Next, the ink coating and varnish coating were cured simultaneously by irradiating with an electron beam to produce a laminate (substrate S3 (PET) / printed layer / varnish layer). The electron beam irradiation conditions were 110 kV and 30 kGy. The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0119] (Example 32) The varnish layer-forming composition 1 used in Example 1 was changed to varnish layer-forming composition 18 having the composition shown in Table 1. A laminate (substrate S1 (CPP / OPP) / varnish layer) was obtained using the same method as in Example 1 except for the above. The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0120] (Comparative Examples 1 to 7) The varnish layer-forming composition 1 used in Example 1 was changed to varnish layer-forming compositions 19 to 25 listed in Table 1. Each varnish layer-forming composition was printed on the substrate using a flexographic printing method in the same manner as in Example 1. Furthermore, electron beam irradiation was performed under the same conditions as in Example 1 to harden the coating film formed by the printing to form a varnish layer, producing a laminate (substrate S1 / varnish layer). The hardness and recovery rate of the varnish layer of the laminate obtained as described above were measured using the methods described above. The results are shown in Table 1.

[0121] (Comparative Examples 8 and 9) The varnish layer-forming composition 1 used in Example 1 was replaced with a commercially available overcoat varnish, which will be described later. Other than that, the varnishes were printed on the substrate by flexographic printing in the same manner as in Example 1. The coating film after printing was immediately dried to form a varnish layer (dried coating film), and a laminate was produced. More details are as follows. Printing was carried out using the same equipment and conditions as in Example 1, with the coating amount after curing being 0.9 to 1.5 g / m². ２ The coating was dried at a temperature of 70°C for a drying time of 3 minutes. Details of the oil-based varnish and water-based varnish used in Comparative Examples 8 and 9 are as follows: <Solvent-based overcoat varnish (oil-based varnish)> HW870 Aquariona A Soft Matte Varnish: Manufactured by Toyo Ink Co., Ltd. <Water-based overcoat varnish (water-based varnish)> JS 1269 PO Matte Regiuser: Manufactured by Toyo Ink Co., Ltd. The hardness of the varnish layer of the laminate obtained as described above was measured using the method described above. An attempt was made to measure the recovery rate of the varnish layer, but the strength of the varnish layer was too weak to measure. The results are shown in Table 1.

[0122] <4> Evaluation of Laminates The laminates produced in the Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 1.

[0123] <Heat resistance> Each laminate was heated twice from the printed surface (varnish layer) side using a heat sealer (TP-705 Ring Seal Tester, Tester Sangyo Co., Ltd.) at 180°C, 0.25 MPa, and for 1 second. The varnish layer in the heat-sealed area was then visually inspected for cracks and peeling, and rated according to the following criteria. A rating of 3 or higher is practically preferable. (Evaluation criteria) 5: slight cracks, no peeling 4: cracks, no peeling 3: slight cracks, no peeling 2: many cracks, no peeling 1: peeling

[0124] <Solvent resistance> For each laminate, a cotton swab immersed in 99.5% ethanol solution was used to rub the varnish layer of the laminate back and forth at a rate of one stroke per second, and the number of strokes until the surface of the varnish layer (cured coating film) was scraped off was measured and evaluated according to the following criteria. A rating of "3" or higher is practically preferable. (Evaluation criteria) 5: 50 strokes or more 4: 40 to less than 50 strokes 3: 20 to less than 30 strokes 2: 10 to less than 20 strokes 1: Less than 10 strokes

[0125] <Slip properties> The dynamic friction coefficient was measured for each laminate and evaluated according to the following criteria. A rating of "2" or higher is practically preferable. The dynamic friction coefficient was measured using a friction tester (HM-3 friction tester, manufactured by Toyo Seiki Seisaku-sho, Ltd.) under the following conditions: speed 100 mm / min, travel distance 50 mm, sled 63 mm x 63 mm, 200 g. (Evaluation criteria) 3: Dynamic friction coefficient less than 0.40 2: Dynamic friction coefficient 0.40 or more but less than 0.45 1: Dynamic friction coefficient 0.45 or more

[0126] <Odor> Each laminate was cut into a piece of 89 mm x 120 mm, and the odor intensity immediately after printing (immediately after the laminate was produced) was evaluated by five people according to the following criteria, and the average value was used for evaluation. A rating of "3" or higher is practically preferable. (Evaluation criteria) 4: Almost no odor was detected 3: A slight odor was detected 2: A clear odor was detected 1: A strong odor was detected

[0127]

[0128]

[0129]

[0130] In Examples 1 to 32, the varnish layer used 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, based on the total mass of the electron beam-curable composition (the composition for forming the varnish layer), and which contained substantially no photopolymerization initiator, had a hardness of 100 to 180 MPa and a recovery rate of 77 to 100%. As a result, the heat resistance, slip resistance, solvent resistance, and low odor were at practical levels.

[0131] 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 thought to be due to the low crosslinking density. In Comparative Example 2, the electron beam curable composition used a large amount of a compound having one (meth)acryloyl group in the molecule, and as with Comparative Example 1, the hardness was low, and the heat resistance and solvent resistance were insufficient. In Comparative Example 3, the recovery rate of the varnish layer was less than 77%, and the heat resistance was insufficient. This is thought to be because the hardness of the varnish layer was within a moderate range, but the coating film was highly brittle.

[0132] In Comparative Example 4, the electron beam curable composition contained 20% by mass of an inert resin having no (meth)acryloyl groups, and the content of compounds having two or more (meth)acryloyl groups in the molecule was less than 80% by mass based on the total mass of the composition, resulting in a hardness of less than 100 MPa and insufficient solvent resistance and slip properties. This is thought to be because the inert resin not incorporated into crosslinks was also present on the surface of the coating film.

[0133] In Comparative Example 5, the hardness of the varnish layer exceeded 180 MPa and the recovery rate of the varnish layer was less than 77%, resulting in insufficient heat resistance. In Comparative Example 6, the recovery rate of the varnish layer was within the range, but the hardness of the varnish layer exceeded 180 MPa, resulting in insufficient heat resistance. Comparative Examples 5 and 6 demonstrate that simply increasing the hardness of the varnish layer is insufficient to meet the heat resistance requirements during heat sealing.

[0134] Comparative Example 7 was a system containing a photopolymerization initiator, and the photopolymerization initiator and its decomposition products became inert components, resulting in inferior heat resistance compared to a system that did not substantially contain a photopolymerization initiator. Furthermore, the photopolymerization initiator and its decomposition products had a strong odor, making it unsuitable for practical use. Comparative Examples 8 and 9 were laminates that used oil-based varnish and water-based varnish as varnish layers, but were not electron beam curable. Compared to electron beam curable types, the hardness was significantly lower, and the recovery rate could not be measured. As a result, the heat resistance and solvent resistance were significantly inferior. Furthermore, there was a strong odor that was thought to be due to residual agents, etc.

[0135] From the above, it can be seen that the laminate of this embodiment has excellent heat resistance, slip resistance, solvent resistance, and low odor because the varnish layer is made of an electron beam curable composition and the hardness and recovery rate of the varnish layer are within a specific range.

Claims

1. A laminate comprising a base material and a varnish layer provided on one surface of the base material, The varnish layer is a layer made of a cured product of an electron beam curable composition containing a (meth)acrylate compound. The (meth)acrylate compound includes a compound having two or more (meth)acryloyl groups in its molecule, and the content of the compound having two or more (meth)acryloyl groups in its molecule is 80% by mass or more, based on the total mass of the electron beam curable composition. The electron beam curable composition substantially does not contain a photopolymerization initiator. The varnish layer is a laminate having a hardness of 100 to 180 MPa as measured by nanoindation, and a recovery rate of 77 to 100% as measured by nanoindation.

2. The laminate according to claim 1, wherein the substrate is a heat-sealable substrate.

3. The laminate according to claim 1, further comprising a heat seal layer in addition to the substrate and the varnish layer.

4. The laminate according to claim 3, comprising the heat seal layer, the substrate, and the varnish layer in this order.

5. The laminate according to claim 1, further comprising a printed layer between the substrate and the varnish layer.

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

7. The laminate according to claim 1, wherein the electron beam curable composition further comprises an extender pigment.

8. The laminate according to claim 1, wherein the electron beam curable composition further comprises resin fine particles.

9. The laminate according to claim 1, wherein the electron beam curable composition further comprises a leveling agent.

10. A packaging material formed using a laminate according to any one of claims 1 to 9.

11. A method for manufacturing a laminate according to any one of claims 1 to 9, An electron beam-curable composition is applied to one side of the substrate to form a coating film. The process involves irradiating the coating film with an electron beam to harden the coating film and forming a varnish layer made of the cured product of the electron beam-curable composition. A manufacturing method wherein the irradiation conditions of the electron beam are an acceleration voltage of 50 to 200 kV and an irradiation dose of 15 to 200 kGy.