Laminate, method for manufacturing a laminate, and packaging bag

Abstract

To provide a laminate that is less prone to wrinkles. [Solution] The laminate is a laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer, wherein the multilayer substrate is laminated in the order of a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer, and the adhesive layer has an electron beam curable adhesive containing a (meth)acrylate resin.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a laminate in which a base material layer, a first adhesive layer, an intermediate layer, a second adhesive layer, and a sealant layer are laminated in this order, having a gas barrier layer on one surface of the intermediate layer, and the base material layer, the intermediate layer, and the sealant layer contain polyethylene, and a laminate obtained by drying the adhesive layer.

[0003] Further, Patent Document 2 discloses a laminate in which a base material layer, an adhesive layer, an inorganic vapor deposition layer, and a sealant layer are laminated in this order, polyethylene is used for the base material layer and the sealant layer, and the laminate is obtained by aging treatment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the conventional technology, polyethylene is used for the base material layer and the sealant layer. However, since polyolefins such as polyethylene have a low melting point, laminates containing polyolefin tend to curl and wrinkle during the drying process and the aging process.

[0006] An object of the present invention is to provide a laminate that is less likely to wrinkle.

Means for Solving the Problems

[0007] The laminate of the present disclosure is a laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer, wherein the multilayer substrate is laminated in the order of a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer, and the adhesive layer has an electron beam curable adhesive containing a (meth)acrylate resin. [Effects of the Invention]

[0008] According to one aspect of the present invention, a laminate that is less prone to wrinkles can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing an example of a laminate. [Figure 2] This figure shows the state of irradiating an uncured laminate with an electron beam. [Figure 3] A flowchart showing an example of a method for manufacturing a laminate. [Figure 4] This is a schematic diagram showing an example of an apparatus for manufacturing a laminate. [Figure 5] This figure shows an example of a packaging bag manufactured using a laminate. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described in detail with reference to the drawings. In each drawing, common parts may be denoted by the same reference numeral and their description may be omitted. Also, the scale of each component in each drawing may differ from the actual scale.

[0011] <Laminate> The laminate of this disclosure comprises a polyolefin sealant layer laminated on a multilayer substrate via an adhesive layer.

[0012] Figure 1 is a cross-sectional view showing an example of a laminate according to the present disclosure. In Figure 1, the laminate 1 is constructed by laminating a multilayer substrate 10, an adhesive layer 20, and a polyolefin sealant layer 30 in that order.

[0013] The multilayer substrate 10 is a substrate formed by laminating a plurality of layers. The multilayer substrate 10 may be formed of a multilayer sheet or a multilayer film.

[0014] The multilayer substrate 10 further has a first polyolefin layer 11, an olefin vinyl alcohol copolymer layer 12, and a second polyolefin layer 13 laminated in this order.

[0015] The first polyolefin layer 11 constitutes a substrate layer containing a polyolefin. The form of the first polyolefin layer 11 is not particularly limited, and for example, it may be formed of a sheet or a film.

[0016] Examples of the polyolefin used in the first polyolefin layer 11 include polyethylene, polypropylene, etc.

[0017] As the polyethylene, for example, high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), very-low-density polyethylene (VLDPE), etc. can be used. Also, from the perspective of environmental load, polyethylene can use biomass-derived polyethylene or recycled polyethylene as all or part of the polyolefin.

[0018] As the polypropylene, for example, biaxially oriented polypropylene (OPP), non-oriented polypropylene (CCP) can be used. Also, from the perspective of environmental load, biomass-derived polypropylene or recycled polypropylene can be used as all or part of the polyolefin.

[0019] The thickness of the first polyolefin layer 11 is not particularly limited, but it is preferably 3 μm or more and 27 μm or less, more preferably 5 μm or more and 25 μm or less, and even more preferably 8 μm or more and 22 μm or less.

[0020] The olefin vinyl alcohol copolymer layer 12 may constitute a barrier layer containing the olefin vinyl alcohol copolymer. The olefin vinyl alcohol copolymer layer 12 is laminated between the first polyolefin layer 11 and the second polyolefin layer 13. The form of the olefin vinyl alcohol copolymer layer is not particularly limited and may be formed, for example, as a sheet or a film.

[0021] Polyolefin-polyvinyl alcohol copolymers are resins obtained by hydrolysis of ethylene-vinyl acetate copolymers. Examples of olefin-vinyl alcohol copolymers include ethylene-vinyl alcohol copolymers and propylene-vinyl alcohol copolymers.

[0022] The thickness of the olefin vinyl alcohol copolymer layer 12 is not particularly limited, but is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 8 μm, and even more preferably 1 μm to 6 μm.

[0023] The second polyolefin layer 13 constitutes a base layer containing polyolefin. The form of the second polyolefin layer 13 is not particularly limited and may be formed, for example, as a sheet or a film.

[0024] Examples of polyolefins used in the second polyolefin layer 13 include polyethylene and polypropylene. The polyolefin used in the second polyolefin layer 13 may be the same type as the polyolefin used in the first polyolefin layer 11, or it may be a different type.

[0025] The thickness of the second polyolefin layer 13 is not particularly limited, but is preferably 3 μm to 27 μm, more preferably 5 μm to 25 μm, and even more preferably 8 μm to 22 μm.

[0026] The thickness of the multilayer substrate 10 is preferably 10 μm or more and 45 μm or less, more preferably 15 μm or more and 35 μm or less, and even more preferably 20 μm or more and 25 μm or less.

[0027] Preferably, the multilayer substrate 10 is formed by co-extrusion, with a first polyolefin layer 11, an olefin vinyl alcohol copolymer layer 12, and a second polyolefin layer 13. Co-extrusion refers to a process in which multiple extruders are used to supply the same type or two or more different resins to dies (molds) and extrude them simultaneously to form a single film.

[0028] The adhesive layer 20 is a layer that bonds each layer in the laminate other than the adhesive layer itself. The adhesive layer 20 is located between the multilayer substrate 10 and the polyolefin sealant layer 30. The adhesive layer 20 contains an electron beam curable (meth)acrylate resin.

[0029] In this specification, (meth)acrylate means either or both acrylate and methacrylate. (Meth)acrylate resins are resins obtained by polymerizing (meth)acrylate monomers having two or more acryloyl groups (CH2=CH-CO-) or methacryloyl groups (CH2=C(CH3)-CO-) in one molecule.

[0030] Furthermore, electron beam-curable resins refer to resins that have functional groups that undergo a curing reaction when irradiated with an electron beam. Here, an electron beam (EB) refers to a stream of electrons obtained by applying an acceleration voltage to electrons. An electron beam (EB) is a type of electrically charged particle beam and has higher energy than electromagnetic waves such as ultraviolet (UV) radiation.

[0031] Examples of electron beam curable (meth)acrylate resins include resins obtained by polymerizing (meth)acrylate monomers such as polyester (meth)acrylate, polyether (meth)acrylate, polyol methacrylate, melamine methacrylate, epoxy (meth)acrylate, and urethane (meth)acrylate. These electron beam curable (meth)acrylate resins may be used individually or in combination of two or more types.

[0032] The molecular weight of the electron beam-curable (meth)acrylate resin is not particularly limited, but is preferably 500 to 100,000 in weight-average molecular weight (MW), more preferably 1,000 to 80,000, and even more preferably 2,000 to 50,000. When the molecular weight of the electron beam-curable (meth)acrylate resin is 500 to 100,000, it is possible to prevent a significant increase in the viscosity of the adhesive and a decrease in the applicability of the adhesive.

[0033] The adhesive used in the adhesive layer 20 is preferably a solvent-free adhesive. Here, a solvent-free adhesive refers to an adhesive that does not contain solvents. Although an adhesive containing electron beam-curable (meth)acrylate resin is a solvent-free adhesive, it can be cured by electron beam irradiation even if it does not contain a solvent as an adhesive, so neither drying nor aging is required to cure the adhesive.

[0034] From this viewpoint, it is preferable that the adhesive layer 20 is cured by electron beam irradiation. The acceleration voltage of the irradiated electron beam is arbitrary, but for example, it is 50kV to 300kV, preferably 70kV to 250kV, and more preferably 90kV to 200kV.

[0035] The manner in which the electron beam is irradiated is not particularly limited, and known electron beam irradiation devices can be used. Examples of electron beam irradiation devices include scanning electron beam irradiation devices, curtain-type electron beam irradiation devices, and plasma discharge type electron beam irradiation devices.

[0036] The thickness of the adhesive layer 20 is not particularly limited, but for example, it is 0.1 μm or more and 5 μm or less, preferably 0.5 μm or more and 4 μm or less, and more preferably 1 μm or more and 3 μm or less. When the thickness of the adhesive layer 20 is 0.1 μm or more and 5 μm or less, adhesion between the multilayer substrate 10 and the polyolefin sealant layer 30 can be ensured.

[0037] The polyolefin sealant layer 30 is a layer containing polyolefins that are fused together by heat. The form of the sealant layer is not particularly limited and may be formed, for example, as a sheet or a film.

[0038] Examples of polyolefins used in the polyolefin sealant layer 30 include polyethylene and polypropylene. The polyolefin used in the polyolefin sealant layer 30 may be the same type as the polyolefin used in the first polyolefin layer 11 and / or the second polyolefin layer 13, or it may be a different type.

[0039] The thickness of the sealant layer 30 is not particularly limited, but can be, for example, 10 μm or more and 250 μm or less, preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 150 μm or less.

[0040] The sealant layer may be a single layer or a multilayer structure. Furthermore, if the sealant layer is a multilayer structure, each layer may be composed of the same type of polyolefin component, or it may be composed of different types of polyolefin components.

[0041] The laminate 1 of this disclosure may have a first polyolefin layer, a second polyolefin layer, and a polyolefin sealant layer, each containing a single polyolefin. Furthermore, such a single polyolefin may be polyethylene.

[0042] The laminate 1 may further have a printed layer (not shown). If the laminate 1 has a printed layer, the printed layer can be laminated on either the side of the multilayer substrate 10 on which the adhesive layer 20 is laminated or the opposite side of that side, preferably laminated between the multilayer substrate 10 and the adhesive layer 20.

[0043] The printing layer is a layer containing ink. The ink constituting the printing layer contains a coloring agent such as a dye and / or pigment, and a binder such as an aqueous and / or solvent-based resin. Examples of resins contained in the ink include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, etc. These resins may be used individually or in mixtures of two or more types.

[0044] The resin contained in the ink of the printing layer may be an electron beam curable resin. Examples of electron beam curable resins include the electron beam curable (meth)acrylate resin mentioned above.

[0045] Furthermore, the printed layer may optionally contain plasticizers, stabilizers, antioxidants, light stabilizers, UV absorbers, curing agents, crosslinking agents, lubricants, antistatic agents, fillers, defoamers, and the like.

[0046] The printed layer can be formed using an ink prepared by thoroughly mixing the ink with a solvent, diluent, etc. Furthermore, in forming the printed layer, such an ink is used with printing methods such as gravure printing, offset printing, letterpress printing, screen printing, transfer printing, and flexographic printing to form a desired printed pattern consisting of characters, figures, symbols, patterns, etc.

[0047] Multiple printed layers may be stacked. If multiple printed layers are stacked, one additional layer may be added between each layer of the stack.

[0048] The laminate 1 is not limited to packaging laminates such as pouches, bags, containers, and packaging films, but can be used for a variety of applications.

[0049] As described above, the laminate of the present disclosure has a polyolefin sealant layer laminated on a multilayer substrate in which a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer are laminated in that order, via an adhesive layer having an electron beam curable adhesive containing a (meth)acrylate resin.

[0050] As a result, in the laminate of this disclosure, a solvent-free adhesive can be used in the adhesive layer, eliminating the need for both drying and aging for the curing of the adhesive layer. Therefore, even if the substrate of the laminate of this disclosure is made of polyolefin, which is a resin with a low melting point, the occurrence of wrinkles is suppressed.

[0051] Furthermore, as described above, the laminate of this disclosure, in which the first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer each contain a single polyolefin, suppresses the occurrence of wrinkles even if the laminate is formed from a polyolefin monomaterial. In addition, such a laminate formed from a polyolefin monomaterial is easily recyclable and has excellent recyclability.

[0052] Furthermore, if the single polyolefin is polyethylene, the polyethylene-containing layer is stretchable and tear-resistant, thus providing flexibility and mechanical strength to the laminate.

[0053] Furthermore, in the laminate of this disclosure, if the adhesive layer is cured by electron beam irradiation, the adhesive layer using an electron beam curable adhesive is reliably cured by electron beam irradiation, so the adhesive layer can be formed without drying or aging.

[0054] Furthermore, in the laminate of this disclosure, if the thickness of the multilayer substrate is 10 μm or more and 45 μm or less, the mechanical strength and barrier properties of the laminate can be improved. Also, if the thickness of the multilayer substrate is 10 μm or more and 45 μm or less, as shown in Figure 2, when the adhesive layer is cured by irradiating the uncured laminate 1' with an electron beam EB from the multilayer substrate side, the EB can sufficiently penetrate to the region in the laminate where the uncured adhesive layer exists, so that the uncured adhesive layer can be reliably cured.

[0055] Furthermore, in the laminate of this disclosure, if the thickness of the olefin vinyl alcohol copolymer layer is 0.1 μm or more, a barrier layer can be formed in the laminate, thereby reliably improving the barrier properties of the laminate. Also, if the thickness of the olefin vinyl alcohol copolymer layer is 10 μm or less, the relative ratio of the olefin vinyl alcohol copolymer to the polyolefin in the laminate is small, so it is less likely to hinder the recycling of monomaterials.

[0056] In the laminate of this disclosure, the multilayer substrate is formed by co-extrusion of a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer, so that the olefin vinyl alcohol copolymer layer, which mainly constitutes the barrier layer, is already included in the multilayer substrate. Therefore, when laminating the multilayer substrate and the sealant layer via an adhesive layer, there is no need to newly laminate the barrier layer.

[0057] Furthermore, by forming the multilayer substrate using this co-extrusion process, the barrier layer within the multilayer substrate can be designed to be thin. Therefore, barrier properties can be imparted to the laminate without increasing the thickness of the multilayer substrate or laminate. Also, even if barrier properties are imparted to the laminate, the thickness of the multilayer substrate does not increase, so as shown in Figure 2, even when curing the adhesive layer by irradiating the uncured laminate 1' with an electron beam EB from the multilayer substrate side, the EB can sufficiently penetrate within the multilayer substrate.

[0058] <Method for manufacturing laminates> The method for manufacturing a laminate according to this disclosure is a method for manufacturing the above-described laminate, that is, a method for manufacturing a laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer. The multilayer substrate is the above-described multilayer substrate, that is, a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer are laminated in this order.

[0059] Furthermore, the first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer constituting the multilayer substrate may contain a single polyolefin. The single polyolefin may also be polyethylene.

[0060] The method for manufacturing the laminate according to this disclosure includes an adhesive coating step, a sealant layer lamination step, and an electron beam irradiation step.

[0061] Figure 3 is a flowchart showing an example of a method for manufacturing a laminate according to the present disclosure. The flowchart shown in Figure 3 corresponds to the manufacturing process of the laminate. In Figure 3, the example of the method for manufacturing a laminate includes a multilayer substrate supply step S1, an adhesive coating step S2, a sealant layer lamination step S3, an electron beam irradiation step S4, and a laminate recovery step S5. Figure 3 is a schematic diagram showing an example of an apparatus for carrying out the method for manufacturing a laminate according to the present disclosure.

[0062] The multilayer substrate supply process S1 supplies the multilayer substrate 10 to the manufacturing line of the laminate 1. The manner in which the multilayer substrate 10 is supplied is not particularly limited, and for example, a long length of multilayer substrate 10 wound on a supply roll is continuously supplied from the supply roll to the manufacturing line.

[0063] In the adhesive coating step S2, a solvent-free adhesive containing the electron beam-curable (meth)acrylate resin described above is applied to the multilayer substrate 10 to form an uncured adhesive layer.

[0064] The method of applying the adhesive is not particularly limited, and known coating devices can be used. Examples of coating devices include gravure coaters, knife coaters, reverse coaters, bar coaters, spray coaters, spin coaters, die coaters, slit coaters, roll coaters, dip coaters, and the like.

[0065] In this specification, the uncured adhesive layer is the adhesive layer containing the coated electron beam-curable resin before it is cured by an electron beam.

[0066] The sealant layer lamination step S3 involves laminating a polyolefin sealant layer 30 onto an uncured adhesive layer formed on a multilayer substrate 10. The manner in which the polyolefin sealant layer 30 is laminated is not particularly limited; for example, the polyolefin sealant layer 30 wound onto a supply roll is continuously supplied onto the uncured adhesive layer formed on the multilayer substrate 10, which is transported from the supply roll to the production line.

[0067] As a result, a polyolefin sealant layer 30 is further laminated on the side of the uncured adhesive layer opposite to the side on which the multilayer substrate 10 is laminated. Consequently, an uncured laminate is obtained in which the multilayer substrate 10, the uncured adhesive layer, and the polyolefin sealant layer 30 are laminated in this order.

[0068] In the electron beam irradiation step S4, the uncured laminate is irradiated with an electron beam (EB).

[0069] The acceleration voltage of the irradiated electron beam is 50kV to 300kV, preferably 70kV to 250kV, and more preferably 90kV to 200kV. The mode of electron beam irradiation is not particularly limited, and known electron beam irradiation devices can be used. Examples of electron beam irradiation devices include scanning electron beam irradiation devices, curtain type electron beam irradiation devices, plasma discharge type electron beam irradiation devices, and the like.

[0070] The direction in which electron beam (EB) is irradiated onto the laminate is not particularly limited, but if either the multilayer substrate 10 or the polyolefin sealant layer 30 is thicker than the other, it is preferable to irradiate the laminate with EB from the thinner side toward the thinner side.

[0071] For example, if the polyolefin sealant layer 30 is thicker than the multilayer substrate 10, it is preferable to irradiate the EB from the multilayer substrate 10 side toward the polyolefin sealant layer 30 side. In this case, irradiating from the multilayer substrate 10 side rather than from the polyolefin sealant layer 30 side makes it easier to reach the uncured adhesive layer within the laminate.

[0072] This results in a laminate in which a multilayer substrate 10, an adhesive layer 20, and a sealant layer 30 are laminated in that order.

[0073] The laminate recovery process S5 recovers the laminate 1 obtained from the manufacturing process of the laminate 1. The manner in which the laminate 1 is recovered is not particularly limited; for example, the obtained laminate 1 may be wound onto a recovery roll and recovered continuously.

[0074] The method for manufacturing the laminate according to this disclosure may further include an adhesive heating step (not shown). In the adhesive heating step, the solvent-free adhesive described above is heated before coating. The adhesive heating step is preferably performed before the adhesive coating step.

[0075] The method of heating the solvent-free adhesive is not particularly limited, and examples include installing a heating device in the storage tank or piping that supplies the solvent-free adhesive.

[0076] The temperature at which the solvent-free adhesive is heated is not particularly limited, but it is preferable to heat it to a temperature at which the viscosity of the solvent-free adhesive decreases to an extent that improves the coating properties of the solvent-free adhesive, depending on the type of solvent-free adhesive.

[0077] The method for manufacturing the laminate according to this disclosure may further include an adhesive heat retention step (not shown). In the adhesive heat retention step, the heated solvent-free adhesive is kept at a constant temperature. The adhesive heating step is preferably performed after the adhesive heating step described above and before the adhesive coating step.

[0078] The method for maintaining the heat of solvent-free adhesives is not particularly limited, and examples include installing a heating device in the storage tank or piping that supplies the solvent-free adhesive.

[0079] The temperature at which the solvent-free adhesive is kept warm is not particularly limited, but it is preferable to set the temperature at which the viscosity of the solvent-free adhesive is reduced to a degree that improves its coatability.

[0080] The method for manufacturing the laminate of this disclosure may further include a printing step (not shown). In the printing step, it is preferable to print an ink containing the above-mentioned electron beam-curable (meth)acrylate resin onto the opposite side of the adhesive layer 20 side of the multilayer substrate 10 to form an uncured printed layer.

[0081] The manner in which the uncured print layer is formed is not particularly limited, but such ink is used to form a desired print pattern consisting of characters, figures, symbols, patterns, etc., using a printing method such as gravure printing, offset printing, letterpress printing, screen printing, transfer printing, or flexographic printing.

[0082] This results in a laminate in which an uncured printed layer, a multilayer substrate 10, an uncured adhesive layer, and a sealant layer 30 are laminated in that order.

[0083] In the method for manufacturing the laminate of this disclosure, as described above, a solvent-free adhesive containing a (meth)acrylate resin is applied to a multilayer substrate in which multiple polyolefin layers are laminated to form an uncured adhesive layer, and the laminate in which a polyolefin sealant layer is laminated to the multilayer substrate via the uncured adhesive layer is irradiated with an electron beam. This provides effects similar to those of the laminate of this disclosure.

[0084] In other words, according to the manufacturing method of the present disclosure, a solvent-free adhesive can be used in the adhesive layer, eliminating the need for any heat-intensive processes such as drying or aging to cure the adhesive layer. Therefore, even if the laminate of the present disclosure is formed from a polyolefin, which is a resin with a low melting point, a laminate with suppressed wrinkle formation can be obtained.

[0085] Furthermore, in the method for manufacturing the laminate of this disclosure, as described above, the first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer each contain a single polyolefin, thereby suppressing the occurrence of wrinkles even if the laminate is formed from a polyolefin monomaterial. In addition, such laminates with a high polyolefin monomaterial ratio are easy to recycle and have excellent recyclability.

[0086] Furthermore, in the method for manufacturing the laminate according to this disclosure, as described above, if the single polyolefin is polyethylene, the polyethylene-containing layer is stretchable and resistant to tearing, thus providing the laminate with flexibility and mechanical strength.

[0087] Furthermore, in the method for manufacturing the laminate according to this disclosure, the solvent-free adhesive can be melted by heating it before coating in the adhesive heating step. As a result, even if the adhesive to be coated is solvent-free, the adhesive can be applied at a low viscosity, making it less likely for uneven coating of the adhesive to occur. Therefore, even when the adhesive layer constituting the laminate is formed using a solvent-free adhesive, a decrease in adhesion between the multilayer substrate and the polyolefin sealant layer can be prevented.

[0088] Furthermore, in the method for manufacturing the laminate according to this disclosure, the temperature of the heated solvent-free adhesive can be maintained until immediately before coating by maintaining the heat of the heated solvent-free adhesive in the adhesive heat retention step. As a result, the heated and melted adhesive can be coated while it is still at a low viscosity, further reducing the likelihood of uneven coating of the adhesive. Therefore, even when the adhesive layer constituting the laminate is formed using a solvent-free adhesive, a decrease in the adhesion between the multilayer substrate and the polyolefin sealant layer can be reliably prevented.

[0089] Furthermore, in the manufacturing method of the laminate of this disclosure, an electron beam is irradiated from the substrate layer side onto the laminate, which is further laminated with an uncured printed layer printed with an ink containing an electron beam-curable (meth)acrylate resin, during the printing process. Since the ink of the printed layer contains an electron beam-curable (meth)acrylate resin, even if a printed layer is laminated onto the laminate, the printed layer can be cured simultaneously with the adhesive layer.

[0090] Furthermore, in the method for manufacturing a laminate according to this disclosure, an electron beam-curable (meth)acrylate resin is used as the ink for forming the printed layer. This allows the uncured printed layer in the laminate to be cured simply by EB irradiation, without requiring either a drying or aging process. Therefore, the method for manufacturing a laminate according to this disclosure can increase the manufacturing efficiency of laminates having a printed layer while reducing the environmental impact.

[0091] <Equipment for manufacturing laminates> The laminate manufacturing apparatus of this disclosure is an apparatus for carrying out the laminate manufacturing method described above. Figure 4 is a schematic diagram of the apparatus for carrying out the laminate manufacturing method of this disclosure. The apparatus 100 shown in Figure 4 comprises a base material layer supply unit 101, a laminate winding unit 102, a transport unit 103, an adhesive coating unit 106, a sealant layer supply unit 107, and an electron beam irradiation unit 108.

[0092] The base material supply unit 101 supplies the multilayer base material 10 to the transport unit 103. As shown in Figure 4, the base material supply unit 101 is configured as a supply roll. A long multilayer base material 10 is wound into a roll on this supply roll. In the base material supply unit 101, the wound multilayer base material 10 is continuously supplied to the transport unit 103. That is, the multilayer base material supply step S1 in the method for manufacturing a laminate of this disclosure is executed in the base material supply unit 101 (see Figure 3).

[0093] The multilayer substrate 10 is constructed by laminating a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer in that order. Furthermore, the first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer constituting the multilayer substrate 10 may contain a single polyolefin. Such a single polyolefin may also be polyethylene.

[0094] The laminate winding unit 102 recovers the laminate 1 from the transport unit 103. As shown in Figure 4, the laminate winding unit 102 is configured as a recovery roll. The obtained laminate 1 is wound into a roll on this recovery roll. In the laminate winding unit 102, the laminate 1 is continuously recovered from the transport unit 103. That is, the multilayer substrate supply step S5 in the method for manufacturing a laminate of this disclosure is executed in the laminate winding unit 102 (see Figure 3).

[0095] The conveying unit 103 constitutes the manufacturing line for the laminate 1 and conveys the multilayer substrate 10. The conveying unit 103 has a plurality of conveying rolls 104 and 105. Each conveying roll 104 and 105 rotates freely. The multilayer substrate 10 is conveyed in the conveying direction D by the rotation of the conveying rolls 104 which constitute the bonding roll and the laminate winding unit 102, driven by the 105.

[0096] The transport speed is arbitrary, but for example, it is 50 m / min or more, preferably 100 m / min to 300 m / min, and more preferably 150 m / min to 250 m / min.

[0097] The adhesive coating unit 106 applies a solvent-free adhesive. The adhesive coating unit 106 is, for example, a nozzle. The nozzle consists of a nozzle head 106. The nozzle head 106 is connected to an adhesive storage unit (not shown) and an adhesive supply unit (not shown) via piping (not shown) and applies the solvent-free adhesive to the multilayer substrate 10 which is transported to the transport unit 103.

[0098] The adhesive storage section stores solvent-free adhesive, which is a raw material for the adhesive layer 20. The adhesive storage section is, for example, a container (not shown), and the container is provided with a replenishment port (not shown) for replenishing the solvent-free adhesive and a supply port (not shown) for supplying the solvent-free adhesive to the adhesive supply section.

[0099] The adhesive storage section may also be provided with a heater (not shown). This heater has the function of heating the solvent-free adhesive stored in the adhesive storage section to a predetermined temperature. The heater provided in the adhesive storage section allows the solvent-free adhesive to be heated before coating. In other words, in the adhesive storage section provided with the heater, the above-described adhesive heating step in the method for manufacturing a laminate of this disclosure is performed.

[0100] Furthermore, the adhesive supply unit supplies solvent-free adhesive to the transport unit 103. The adhesive supply unit is, for example, a pipe (not shown). The pipe is connected to the supply port of the adhesive storage unit and supplies the solvent-free adhesive supplied from the adhesive storage unit to the adhesive coating unit 106.

[0101] The adhesive supply unit may also be provided with a heater (not shown). This heater has the function of heating the solvent-free adhesive supplied to the adhesive storage unit to a predetermined temperature. The heater provided in the adhesive storage unit allows the solvent-free adhesive to be heated before coating, and also allows the heat of the solvent-free adhesive heated in the adhesive storage unit to be maintained. In other words, in the adhesive supply unit provided with the heater, the above-described adhesive heating step and / or adhesive heat retention step in the method for manufacturing a laminate of this disclosure is performed.

[0102] In the adhesive coating section 106, a solvent-free adhesive is applied to the multilayer substrate 10 to form an uncured adhesive layer, and this uncured adhesive layer is laminated onto the multilayer substrate 10. In other words, the adhesive coating step S2 in the manufacturing method of the laminate of this disclosure is performed in the adhesive coating section 106 (see Figure 3).

[0103] The sealant layer supply unit 107 supplies the sealant layer 30 to the conveying unit 103. The sealant layer supply unit 107 constitutes a supply roll. A long sealant layer 30 is wound onto this supply roll. As shown in Figure 4, in the sealant layer supply unit 107, the long sealant layer 30 is supplied to the conveying unit 103, and after passing through the conveying roll 104, it is laminated onto the uncured adhesive layer 20, resulting in an uncured laminate 1'.

[0104] The electron beam irradiation unit 108 irradiates the uncured laminate 1' (a laminate consisting of a multilayer substrate 10, an uncured adhesive layer, and a sealant layer 30) with an electron beam EB. As shown in Figure 4, the electron beam irradiation unit 108 is located on the multilayer substrate 10 side of the laminate 1', near the laminate winding unit 102. In the electron beam irradiation unit 108, the acceleration voltage of the irradiated electron beam is controlled to be between 50kV and 300kV.

[0105] As a result, in the electron beam irradiation unit 108, an electron beam EB with an acceleration voltage of 50kV to 300kV is irradiated onto the uncured laminate 1' from the multilayer substrate 10 side, as shown in Figure 4. In other words, the electron beam irradiation step in the manufacturing method of the laminate of this disclosure is performed in the electron beam irradiation unit 108 (see Figure 2).

[0106] As a result, in the apparatus 100, the laminate 1' hardens, and a laminate 1 (a laminate in which a multilayer substrate 10, an adhesive layer 20, and a sealant layer 30 are laminated) is obtained. The obtained laminate 1 is recovered in the laminate winding section 102 as described above.

[0107] In the example apparatus shown in Figure 4, the nozzle head of the adhesive coating unit 106 is positioned to coat the multilayer substrate 10 with a solvent-free adhesive. However, the manner in which the solvent-free adhesive is applied is not limited to this. For example, the nozzle head of the adhesive coating unit may be positioned to coat the sealant layer 30 before lamination. Even in such a case, the solvent-free adhesive is applied to the multilayer substrate 10, forming an uncured adhesive layer.

[0108] Furthermore, a printing section (not shown) may be provided between the transport roll 104 and the electron beam irradiation section 108. The configuration of the printing section is not particularly limited, and for example, the printing section may include a nozzle for dispensing ink, an ink tank (not shown) for storing ink, and the like.

[0109] The printing unit prints an ink containing an electron beam-curable (meth)acrylate resin onto the side of the multilayer substrate 10 opposite to the adhesive layer 20. As a result, the ink containing the electron beam-curable (meth)acrylate resin is printed onto the side of the multilayer substrate 10 opposite to the adhesive layer 20, forming an uncured printed layer. In other words, the printing unit performs the above-described printing step in the manufacturing method of the laminate of this disclosure.

[0110] If such a printed section is provided, the electron beam irradiation section 108 further irradiates the uncured laminate 1' (a laminate in which an uncured printed layer, a multilayer substrate 10, an uncured adhesive layer, and a sealant layer 30 are laminated) with an electron beam EB.

[0111] As a result, the laminate 1' hardens, and a laminate with a printed layer is obtained (a laminate in which a printed layer, a multilayer substrate, an adhesive layer, and a sealant layer are laminated).

[0112] As described above, the laminate manufacturing apparatus of the present disclosure provides the same effects as those in the laminate manufacturing method of the present disclosure when the laminates are laminated using the laminate manufacturing method of the present disclosure.

[0113] In other words, in the laminate manufacturing apparatus of the present disclosure, a solvent-free adhesive can be used in the adhesive layer, eliminating the need for both drying and aging for the curing of the adhesive layer. Therefore, even if the laminate substrate of the present disclosure is made of polyolefin, which is a resin with a low melting point, a laminate with suppressed wrinkle formation can be obtained.

[0114] Furthermore, in the manufacturing apparatus for laminates of this disclosure, as described above, the first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer each contain a single polyolefin, thereby suppressing the occurrence of wrinkles even when the laminate is formed from a polyolefin monomaterial. In addition, such laminates formed from a polyolefin monomaterial are easily recyclable and have excellent recyclability.

[0115] Furthermore, in the method for manufacturing the laminate according to this disclosure, as described above, if the single polyolefin is polyethylene, the polyethylene-containing layer is stretchable and resistant to tearing, thus providing the laminate with flexibility and mechanical strength.

[0116] <Packaging bag> The laminate 1 can be used to manufacture a packaging bag. The packaging bag only needs to have at least some of its components made from the laminate 1. The use of the packaging bag is not particularly limited, but it is suitable for use in applications where the contents are refilled once or multiple times into a main container used when the contents are consumed, such as for disposable use, refilling, storage, or storing goods.

[0117] The laminate 1 may have a portion for opening or cutting the packaging bag. The portion for opening or cutting may have a structure processed in the thickness direction of the film, such as a perforation, notch, or half-cut groove, or it may have a shape that suggests opening or cutting within the surface of the film, such as a thinly protruding spout, or it may be an indication such as an arrow, line, or dot printed on it. Cutting the packaging bag is not limited to cutting the opening portion, but may also be used to cut between or around packaging bags in areas where two or more packaging bags are formed in a continuous manner, or in areas where tags or display portions are continuous around the packaging bag.

[0118] Specific examples of packaging bags are not limited to three-side sealed bags, four-side sealed bags, pillow bags, flat bags, gusset bags, and standing pouches. Figure 5 shows an example of a packaging bag manufactured using a laminate. In Figure 5, the packaging bag 200 is a standing pouch formed from a pair of body members 201 and a bottom member 202 folded in half along a fold line 203.

[0119] The packaging bag 200 has two body members 201, one at the front and one at the back. The planar shapes of the front and back body members 201 may be the same. The bottom member 202 is folded in along a fold line 203 so that its outer surfaces face each other. Above the fold line 203, body seal portions 204 are formed on the left and right sides, and the inner surfaces of the front and back body members 201 are joined together. The inner surfaces of the body members 201 correspond to the sealant layer 30 of the laminate 1.

[0120] The bottom member 202 is sandwiched between the front and rear body members 201 with the fold line 203 facing upwards. Below the fold line 203, a bottom seal portion 205 is formed where the inner surface of the bottom member 202 is joined to the inner surface of the body member 201. The bottom seal portion 205 joins the area of ​​the bottom member 202 demarcated by the fold line 203 to the body member 201 on the same side in the front-to-back direction. By spreading the bottom member 202 relative to the fold line 203, the packaging bag 200 can be made to stand on its own.

[0121] If the packaging bag 200 has a body member 201 and a bottom member 202, the laminate 1 of the embodiment may be used for either the body member 201 or the bottom member 202, or for both. From the viewpoint of improving tearability, it is preferable to use the laminate 1 for the body member 201. Such a packaging bag 200 is suitable for packaging applications that enclose liquids.

[0122] The dimensions of the packaging bag 200 are not particularly limited, but for example, when used as a refill container, the height in the vertical direction is approximately 80-500 mm, the width in the horizontal direction is approximately 70-300 mm, and the filling volume is approximately 80-3000 cm³. 3 The degree can be mentioned. The state of the contents can be fluids such as liquids, powders, or granules, or solids such as articles. The type of contents is not particularly limited, but can be detergents, chemicals, cosmetics, pharmaceuticals, beverages, seasonings, inks, paints, fuels, etc.

[0123] The packaging bag 200 may have a filling opening, a spout, etc. For example, the top of the packaging bag 200 may be open between the front and rear body members 201, allowing it to be used for filling or dispensing contents. After filling with contents, the body members 201 may be joined together to seal the packaging bag 200. When opening the packaging bag 200, the area where the body members 201 were joined can be easily torn. Although not specifically shown, the spout may be formed as a thin projection at the top or corner of the packaging bag 200. The spout may be made of film or be of the spout type. When a spout is installed diagonally at a corner, biaxial stretching is advantageous in terms of drop strength, etc.

[0124] The packaging bag 200 may be formed solely from the laminate 1, or it may be combined with accessories such as labels, tags, straws, and outer boxes.

[0125] Since the packaging bag of this disclosure uses the laminate of this disclosure, the same effects as those of the laminate can be obtained. In other words, it is possible to obtain a packaging bag that improves manufacturing efficiency while reducing environmental impact without reducing the adhesive strength of each layer of the laminate that constitutes the packaging bag. [Examples]

[0126] The present invention will be described in more detail below using examples. The examples and comparative examples were evaluated by the following tests.

[0127] [Laminate (test specimen)] Referring to Figures 1-4, a laminate was prepared as a test specimen in which a multilayer substrate, adhesive layer, and sealant layer were laminated in this order. The multilayer substrate was prepared in advance with substrate layer 1, barrier layer, and substrate layer 2 laminated in this order. Substrate layer 1 corresponds to the first polyolefin layer, the barrier layer corresponds to the ethylene vinyl alcohol copolymer layer, substrate layer 2 corresponds to the second polyolefin layer, the adhesive layer corresponds to an electron beam curable adhesive containing (meth)acrylate resin, and the sealant layer corresponds to a polyolefin sealant layer.

[0128] <Wrinkles in laminated material> As a test specimen, a 700mm wide roll of film was laminated for 1000m at 80m / min, and wrinkles were visually inspected during the process. Wrinkle evaluation was performed according to the following criteria: ○ was rated as good, and × was rated as poor. ○: No wrinkles ×: Wrinkles were found.

[0129] <Gas barrier properties> The oxygen transmission rate (OTR) of the test specimens was measured according to the JIS K-7126B method under conditions of 30°C and 70% RH (relative humidity). Gas barrier properties were evaluated according to the following criteria. A gas barrier property evaluation of ◎ or ○ was considered good, and a × was considered poor. ◎: The value of OTR is 5cc / (m 2 Less than (day / atm) ○: The value of OTR is 5cc / (m 2 ·day · atm) or more 10cc / (m 2 Less than (day / atm) ×: The value of OTR is 10cc / (m 2 ·day · atm) or more

[0130] [Adhesiveness] The test specimens were measured using a Tensilon tensile tester under the following conditions: T-type peel, sample width 15 mm, gripping distance 10 mm, and tensile speed 300 mm / min, in an atmosphere of 24°C and 65% RH (relative humidity). Adhesion was evaluated according to the following criteria. Adhesion was evaluated as good (◎, ○, △) and poor (×). ◎: No delamination occurred, but cohesive failure occurred in one of the layers of the laminate. ○: Although some delamination occurred in a very small area, delamination itself was hardly observed. △: Delamination was observed in some areas. ×: There were uncured areas, which caused cohesive failure of the adhesive, resulting in significantly weaker strength.

[0131] Furthermore, delamination refers to the separation of each layer—the substrate layer, barrier layer, and sealant layer—from the adhesive layer within the laminate. Additionally, cohesive failure of any layer within the laminate refers to cohesive failure of the substrate layer, barrier layer, and / or sealant layer within the laminate.

[0132] <Recyclability> The recyclability of the test specimens was evaluated based on the content of the same type of polyolefin in the laminate. The evaluation of recyclability was performed according to the following criteria: A value of ○ was calculated, and the recyclability was evaluated as good if it was ○, and poor if it was ×. ○: The content of the same type of polyolefin was 95% by mass or more. ×: The content of the same type of polyolefin was 85% by mass or more and less than 95% by mass.

[0133] The following are examples of embodiments and comparative examples.

[0134] [Example 1] A laminate was prepared by layering polyethylene (PE) resin 10 μm as the base layer 1 of a multilayer substrate, ethylene vinyl alcohol copolymer (EVOH) resin 2 μm as the barrier layer, polyethylene (PE) resin 10 μm as the base layer 2, EB-curable acrylate adhesive 2 μm as the adhesive layer, and polyethylene (PE) 100 μm as the sealant layer, in this order. This laminate was irradiated with an electron beam (EB) with an acceleration voltage of 125 kV from the base layer 1 side of the multilayer substrate. The conditions and evaluation results for Example 1 are shown in Table 1.

[0135] [Example 2] The thickness of the polyethylene (PE) resin as base layer 1 was set to 20 μm, and the thickness of the polyethylene (PE) resin as base layer 2 was also set to 20 μm. Otherwise, the laminate was fabricated and evaluated in the same manner as in Example 1. The conditions and evaluation results for Example 2 are shown in Table 1.

[0136] [Example 3] The thickness of the EB-curing acrylate adhesive used as the adhesive layer was set to 5 μm. Otherwise, the laminate was prepared and evaluated in the same manner as in Example 1. The conditions and evaluation results for Example 3 are shown in Table 1.

[0137] [Comparative Example 1] In this comparative example, no barrier layer was laminated onto the multilayer substrate. Otherwise, the laminate was prepared and evaluated in the same manner as in Example 1. The conditions and evaluation results for Comparative Example 1 are shown in Table 1.

[0138] [Comparative Example 2] Instead of an EB-curing acrylate adhesive, a solvent-based urethane adhesive was used as the adhesive layer, and a general dry lamination process (solvent drying in an oven and heating aging after lamination) was carried out. Otherwise, the laminate was prepared and evaluated in the same manner as in Example 1. The conditions and evaluation results for Comparative Example 2 are shown in Table 1.

[0139] [Table 1]

[0140] Table 1 shows that in Examples 1 to 3, the laminates in which a polyolefin sealant layer was laminated via an adhesive layer containing an electron beam-curable adhesive (meth)acrylate resin to a multilayer substrate in which a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer were laminated in that order, showed suppressed wrinkle formation and good barrier properties, adhesion, and recyclability.

[0141] On the other hand, as in Comparative Example 1, the laminate without a barrier layer exhibited poor barrier properties. Furthermore, as in Comparative Example 2, the laminate that underwent a drying process developed wrinkles.

[0142] The embodiments disclosed above include, for example, the following aspects:

[0143] <1> A laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer, The aforementioned multilayer substrate is constructed by laminating a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer in this order. A laminate in which the adhesive layer has an electron beam curable adhesive containing a (meth)acrylate resin.

[0144] <2> The first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer each contain a single polyolefin, <1> The laminate described above.

[0145] <3> The above single polyolefin is polyethylene. <2> The laminate described above.

[0146] <4> The adhesive layer is cured by electron beam irradiation. <1> ~ <3> A laminate as described in any one of the items.

[0147] <5> The thickness of the multilayer substrate is 10 μm or more and 45 μm or less. <1> ~ <4> A laminate as described in any one of the items.

[0148] <6> The thickness of the olefin vinyl alcohol copolymer layer is 0.1 μm or more and 10 μm or less. <1> ~ <5> A laminate as described in any one of the items.

[0149] <7> The multilayer substrate is formed by co-extrusion of the first polyolefin layer, the olefin vinyl alcohol copolymer layer, and the second polyolefin layer. <1> ~ <6> A laminate as described in any one of the items.

[0150] <8> A method for manufacturing a laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer, The aforementioned multilayer substrate is constructed by laminating a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer in this order. An adhesive coating step involves applying a solvent-free adhesive containing a (meth)acrylate resin to the multilayer substrate to form an uncured adhesive layer, A sealant layer lamination step is performed by laminating a polyolefin sealant layer onto the adhesive layer formed on the multilayer substrate, A method for manufacturing a laminate, comprising: an electron beam irradiation step of irradiating a laminate, in which the polyolefin sealant layer is laminated on the multilayer substrate via the uncured adhesive layer, with an electron beam having an acceleration voltage of 50 kV or more and 300 kV or less.

[0151] <9> The above process does not involve drying or aging. <8> A method for manufacturing the laminate described above.

[0152] <10> the above <1> ~ <7> A packaging bag formed using a laminate as described in any one of the items.

[0153] Although embodiments of this disclosure have been described above, the present invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope of the invention as described in the claims. [Explanation of Symbols]

[0154] 1. Laminate 1' Uncured adhesive layer 10 Multilayer base material 11. First polyolefin layer 12. Olefin vinyl alcohol copolymer layer 13. Second polyolefin layer 20 Adhesive layer 30 sealant layer 100 devices 101 Base material layer supply section 102 Laminate winding section 103 Conveying Section 104 Conveyor Rolls 105 Conveyor Rolls D Conveying direction 106 Adhesive coating section 107 Sealant layer supply section 108 Electron beam irradiation section 108 EB electron beam 200 packaging bags 201 Body parts 202 Bottom member 203 Fold lines 204 Body seal section 205 Bottom seal section

Claims

1. A laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer, The multilayer substrate is constructed by laminating a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer in this order. A laminate in which the adhesive layer has an electron beam curable adhesive containing a (meth)acrylate resin.

2. The laminate according to claim 1, wherein the first polyolefin layer, the second polyolefin layer, and the polyolefin sealant layer each contain a single polyolefin.

3. The laminate according to claim 2, wherein the single polyolefin is polyethylene.

4. The laminate according to claim 1, wherein the adhesive layer is cured by electron beam irradiation.

5. The laminate according to claim 1, wherein the thickness of the multilayer substrate is 10 μm or more and 45 μm or less.

6. The laminate according to claim 1, wherein the thickness of the olefin vinyl alcohol copolymer layer is 0.1 μm or more and 10 μm or less.

7. The laminate according to claim 1, wherein the multilayer substrate is formed by co-extrusion of the first polyolefin layer, the olefin vinyl alcohol copolymer layer, and the second polyolefin layer.

8. A method for manufacturing a laminate in which a polyolefin sealant layer is laminated on a multilayer substrate via an adhesive layer, The aforementioned multilayer substrate is constructed by laminating a first polyolefin layer, an olefin vinyl alcohol copolymer layer, and a second polyolefin layer in this order. An adhesive coating step involves applying a solvent-free adhesive containing a (meth)acrylate resin to the multilayer substrate to form an uncured adhesive layer, A sealant layer lamination step is performed by laminating a polyolefin sealant layer onto the adhesive layer formed on the multilayer substrate, A method for manufacturing a laminate, comprising: an electron beam irradiation step of irradiating a laminate, in which the polyolefin sealant layer is laminated on the multilayer substrate via the uncured adhesive layer, with an electron beam having an acceleration voltage of 50 kV or more and 300 kV or less.

9. A method for producing a laminate according to claim 8, wherein neither drying nor aging is performed.

10. A packaging bag formed using the laminate described in any one of claims 1 to 7.

Images