Gas barrier laminate, manufacturing method thereof, container, and raw sheet

Abstract

To provide a gas barrier laminate capable of obtaining a container having excellent gas barrier properties, a method for producing the same efficiently, the container, and a raw roll.SOLUTION: A method for producing a gas barrier laminate of the present disclosure includes the steps of: preparing a first raw roll which includes a gas barrier layer and a first adhesion layer provided on a first surface of the gas barrier layer, and is wound with a first laminate in which the first adhesion layer is exposed on a surface; preparing a second raw roll which is wound with a paper base material; and laminating the first laminate and the paper base material while extruding an adhesive resin containing an olefin resin, between the first adhesion layer of the first laminate fed from the first raw roll and the paper base material fed from the second raw roll.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a gas barrier laminate, a method for producing the same, a container, and a raw sheet thereof. [Background technology]

[0002] Conventionally, laminates primarily made of paper have been used in the field of packaging materials. Patent Document 1 discloses a laminate comprising a paper substrate, an adhesive resin layer of a specific thickness, a specific barrier layer, and a heat-sealable resin layer. Patent Document 2 discloses a laminate comprising an outermost layer, a paper substrate, an adhesive layer, a barrier layer comprising an inorganic oxide vapor-deposited film, a gas barrier coating film, and a protective film on one side of a substrate film, and an innermost layer laminated in this order.

[0003] On the other hand, the paper substrate used in the laminate material for paper containers is required to have a certain thickness in order to ensure the container's self-supporting ability and strength. However, a paper substrate with sufficient thickness does not provide sufficient interlayer adhesive strength when laminated to another substrate via an adhesive layer, and is prone to interlayer delamination. In particular, when laminating a paper substrate with a gas barrier coating film of a barrier film, as in Patent Document 2, there is a problem in that sufficient interlayer adhesive strength is not obtained, and as a result, sufficient gas barrier properties are not exhibited.

[0004] To address such problems, Patent Document 3 discloses a laminate material comprising, in this order, a primer layer, a barrier coat layer, a first inorganic oxide vapor-deposited layer, a substrate film, and a second inorganic oxide vapor-deposited layer, in which the primer layer comprises a barrier film containing a specific polyolefin polymer.

[0005] Patent Document 4 discloses a laminate in which an outermost layer, a paper base layer, a first adhesive resin layer, a resin film layer, an aluminum foil layer, a second adhesive resin layer, and an innermost layer are laminated together, with the aluminum foil constituting the aluminum foil layer facing in a specific direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-171649 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-154524 [Patent Document 3] Japanese Patent Application Publication No. 2020-157717 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-137880 Summary of the Invention [Problem to be solved by the invention]

[0007] Such containers (paper containers) generally have a container body having a top, sides, and bottom made of packaging material. For example, when the container body is rectangular, the container can be obtained by forming lines in the packaging material beforehand, bending the packaging material along the lines, and heating and bonding the packaging material together. When the container body is cylindrical, the container can be obtained by heating and bonding separate members that respectively constitute the top, sides, and bottom. These members can then be obtained by bending the packaging material while heating it to form the desired shape.

[0008] Therefore, if the adhesion between the gas barrier layer and the adhesive resin layer is insufficient, voids are likely to form between the gas barrier layer and the adhesive resin layer when the container is bent. When voids form, the paper substrate is prone to bending at sharp angles without conforming to the gas barrier layer, which tends to increase the load on the gas barrier layer. As a result, cracks and pinholes form in the gas barrier layer, reducing the gas barrier properties of the container.

[0009] In particular, when the container body is cylindrical, cracks and pinholes are likely to occur in the gas barrier layer because the packaging material is bent while being heated.

[0010] The laminates disclosed in Patent Documents 1 to 3 and the laminate disclosed in Patent Document 4 have room for improvement in terms of adhesion between layers.

[0011] Generally, packaging materials are produced by bonding an outer layer material having a paper base material and an inner layer material having a gas barrier layer together with a resin that forms an adhesive resin layer so that the paper base material and the gas barrier layer face each other.

[0012] In order to improve the adhesion between the gas barrier layer and the adhesive resin layer, it is conceivable to form an adhesion layer made of a resin that improves adhesion to the adhesive resin layer on the surface of the gas barrier layer of the inner layer material. However, if a urethane-based adhesive or an emulsion-type vinyl acetate adhesive is used as such a resin, the adhesion layer becomes sticky, making it impossible to wind the inner layer material into a roll. Therefore, the adhesion layer must be formed on the surface of the gas barrier layer during the manufacturing process in which the outer layer material and the inner layer material are bonded together, which requires large-scale manufacturing equipment and is inefficient. [Means for solving the problem]

[0013] The present disclosure provides a gas barrier laminate that can provide a container with excellent gas barrier properties, a method for efficiently producing the same, the container, and a raw sheet.

[0014] A method for producing a gas barrier laminate according to one aspect of the present disclosure includes: preparing a first raw web around which a first laminate is wound, the first laminate including a gas barrier layer and a first adhesive layer provided on a first surface of the gas barrier layer, with the first adhesive layer exposed on a surface thereof; preparing a second roll around which a paper substrate is wound; a step of laminating the first laminate and the paper substrate while extruding an adhesive resin containing an olefin resin between the first adhesive layer of the first laminate delivered from the first roll and the paper substrate delivered from the second roll; Equipped with the first adhesive layer contains first olefin copolymer particles having a number average particle diameter of 1 μm or less, The first olefin copolymer particles contain structural units derived from unsaturated carboxylic acid or its anhydride, and the content of the structural units is 0.01 to 5 mass % based on the total amount of the first olefin copolymer particles.

[0015] A method for producing a gas barrier laminate according to one aspect of the present disclosure can efficiently produce a gas barrier laminate with excellent gas barrier properties. It is believed that this effect is achieved by the following mechanism. Specifically, the first adhesion layer contains first olefin copolymer particles. The first olefin copolymer particles contain structural units derived from an unsaturated carboxylic acid or its anhydride, and the content of these structural units within the above-mentioned range improves adhesion to an adhesive resin containing an olefin resin. Furthermore, the number-average particle diameter of the first olefin copolymer particles is 1 μm or less, so that the first adhesion layer has improved adhesion to the adhesive resin while reducing tackiness. Because the tackiness of the first adhesion layer is reduced, the first laminate with the first adhesion layer exposed on its surface can be wound up as a raw web, eliminating the need to form an adhesion layer during the manufacturing process of bonding the first laminate to a paper substrate. Therefore, the method for producing a gas barrier laminate according to one aspect of the present disclosure can efficiently produce a gas barrier laminate with excellent gas barrier properties.

[0016] The first laminate may further include a second adhesion layer provided on the second surface of the gas barrier layer, so that the resulting gas barrier laminate has even better gas barrier properties. The second adhesion layer may include second olefin copolymer particles having a number average particle size of 1 μm or less, and the second olefin copolymer particles may contain structural units derived from an unsaturated carboxylic acid or an anhydride thereof, and the content of the structural units may be 0.01 to 5 mass% based on the total amount of the second olefin copolymer particles.

[0017] The melting points of the first and second olefin copolymer particles may be 120°C or higher, as this improves the heat resistance of the resulting gas barrier laminate.The gas barrier layer may have a film substrate containing at least a polypropylene film and a vapor-deposited layer containing an inorganic oxide provided on the surface of the film substrate, as this improves the recyclability and water resistance of the resulting gas barrier laminate.

[0018] A gas barrier laminate according to another aspect of the present disclosure has a laminate structure comprising, in this order, a paper substrate, an adhesive resin layer containing an olefin resin, a first adhesion layer containing first olefin copolymer particles having a number average particle size of 1 μm or less, a gas barrier layer, and a sealant layer, wherein the first olefin copolymer particles contain structural units derived from an unsaturated carboxylic acid or an anhydride thereof, and the content of the structural units is 0.01 to 5 mass% based on the total mass of the first olefin copolymer particles. This gas barrier laminate has excellent gas barrier properties.

[0019] In one embodiment, the gas barrier laminate has even better gas barrier properties and may further include a second adhesive layer between the gas barrier layer and the sealant layer, the second adhesive layer containing second olefin copolymer particles having a number average particle size of 1 μm or less, the second olefin copolymer particles containing structural units derived from an unsaturated carboxylic acid or an anhydride thereof, and the content of the structural units may be 0.01 to 5 mass% based on the total amount of the second olefin copolymer particles.

[0020] The melting points of the first and second olefin copolymer particles may be 120°C or higher, which improves the heat resistance of the gas barrier laminate. The gas barrier layer may have a film substrate containing at least a polypropylene film, and a vapor-deposited layer containing an inorganic oxide provided only on one surface of the film substrate, which improves the recyclability and water resistance of the gas barrier laminate. The vapor-deposited layer may have a thickness of 30 nm or more and 300 nm or less, which improves the gas barrier properties of the gas barrier laminate.

[0021] A container according to yet another aspect of the present disclosure is made of the gas barrier laminate. This container has excellent gas barrier properties.

[0022] A raw web according to yet another aspect of the present disclosure is a rolled laminate including a gas barrier layer and a first adhesive layer provided on a first surface of the gas barrier layer, with the first adhesive layer exposed on the surface. The first adhesive layer contains first olefin copolymer particles having a number average particle size of 1 μm or less, and the first olefin copolymer particles contain structural units derived from an unsaturated carboxylic acid or an anhydride thereof, with the content of the structural units being 0.01 to 5 mass% based on the total amount of the first olefin copolymer particles.

[0023] The laminate may further include a second adhesive layer provided on the second surface of the gas barrier layer, the second adhesive layer containing second olefin copolymer particles having a number average particle diameter of 1 μm or less, the second olefin copolymer particles containing structural units derived from an unsaturated carboxylic acid or an anhydride thereof, and the content of the structural units may be 0.01 to 5 mass% based on the total amount of the second olefin copolymer particles.

[0024] The melting points of the first and second olefin copolymer particles may be 120° C. or higher. The gas barrier layer may have a film substrate containing at least a polypropylene film and a vapor-deposited layer containing an inorganic oxide provided on the surface of the film substrate. [Effects of the Invention]

[0025] According to the present disclosure, there are provided a gas barrier laminate that can provide a container with excellent gas barrier properties, a manufacturing method that can efficiently manufacture the same, a container, and a raw sheet. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a cross-sectional view that schematically illustrates one embodiment of a gas barrier laminate according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically showing an embodiment of a first laminate wound around a first web. [Figure 3] FIG. 3 is a schematic diagram showing an example of a laminating device that can be used in one embodiment of the method for producing a gas barrier laminate according to the present disclosure. [Figure 4] FIG. 4 is a perspective view schematically illustrating one embodiment of a container according to the present disclosure. [Figure 5] FIG. 5 is a perspective view schematically showing another embodiment of a container according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0028] [Gas barrier laminate] The gas barrier laminate according to this embodiment will be described below. FIG. 1 is a cross-sectional view schematically showing the gas barrier laminate according to this embodiment. As shown in FIG. 1, the laminate 10 according to this embodiment has a laminate structure including, in this order, a paper substrate 1, an adhesive resin layer 3, a first adhesion layer 5a, a gas barrier layer 7, a second adhesion layer 5b, and a sealant layer 9. A protective layer 11 is disposed on the surface of the paper substrate 1 opposite to the surface that contacts the adhesive resin layer 3. The gas barrier layer 7 includes, in this order, a film substrate 7a that contacts the first adhesion layer 5a, a vapor deposition layer 7b, and an overcoat layer 7c. Each component of the laminate 10 will be described below.

[0029] (Paper base material) For example, paper having shapeability, flex resistance, rigidity, firmness, strength, etc. can be used as the paper substrate 1. Examples of such paper that can be used include bleached or unbleached paper with strong sizing properties, pure white roll paper, kraft paper, paperboard, and processed paper.

[0030] The basis weight of the paper substrate 1 is 80 to 600 g / m because the resulting container has better gas barrier properties. 2 It is preferable that the thickness is 200 to 450 g / m 2 It is more preferable that:

[0031] On the paper substrate 1, desired printed patterns such as letters, figures, pictures, symbols, etc. can be formed arbitrarily by a normal printing method.

[0032] (adhesive resin layer) The adhesive resin layer 3 contains an olefin-based resin. Examples of olefin-based resins include branched low-density polyethylene, linear low-density polyethylene, polypropylene, polyethylene-polyvinyl acetate copolymers, acid anhydride-modified polyolefins such as terpolymers such as ethylene-ethyl acrylate-maleic anhydride, and epoxy compound-modified polyolefins such as ethylene-glycidyl methacrylate copolymers. Among these, branched low-density polyethylene, linear low-density polyethylene, and polypropylene are preferred because they facilitate cleaning of the extrusion device after processing and are highly recyclable. The olefin-based resins may be used alone or in combination of two or more.

[0033] The content of the olefin resin in the adhesive resin layer 3 may be 80% by mass or more, 90% by mass or more, or 95% by mass or more based on the total amount of the adhesive resin layer 3.

[0034] The thickness of the adhesive resin layer 3 is, for example, preferably 10 to 40 μm, and more preferably 15 to 25 μm.

[0035] (First adhesive layer) The first adhesive layer 5a contains (A) first olefin copolymer particles (hereinafter also referred to as component (A)) having a number average particle diameter of 1 μm or less, and the component (A) contains a structural unit derived from (A1) unsaturated carboxylic acid or its anhydride (hereinafter also referred to as component (A1)), and the content of the structural unit is 0.01 to 5 mass% based on the total amount of the first olefin copolymer particles.

[0036] The number average particle diameter of the first olefin copolymer particles may be, for example, 50 nm to 200 nm, from the viewpoint of facilitating uniform dispersion of the first olefin copolymer particles and improving film-forming properties. The number average particle diameter of the first olefin copolymer particles is a value measured by dynamic light scattering using a particle size distribution analyzer.

[0037] The melting point of the first olefin copolymer particles is preferably 120° C. or higher, as this improves the heat resistance of the gas barrier laminate. The melting point of the first olefin copolymer particles can be measured using a differential scanning calorimeter (DSC).

[0038] The first olefin copolymer particles may have structural units derived from an (A2) olefin compound (hereinafter also referred to as component (A2)).The first olefin copolymer particles may have structural units derived from an (A3) (meth)acrylic acid ester (hereinafter also referred to as component (A3)).

[0039] The contents of the (A2) and (A3) components in the first olefin copolymer particles may be 95 to 99.99 mass% based on the total mass of the first olefin copolymer particles, and the mass ratio of the (A2) component to the (A3) component in the first olefin copolymer ((A2) / (A3)) may be (A2) / (A3)=55 / 45 to 99 / 1.

[0040] The first adhesive layer 5a may further contain a (B) polyester-based resin (hereinafter also referred to as component (B)). The component (B) may have an anionic group. Examples of the anionic group include a carboxyl group, a sulfonic acid group, a sulfate group, and a phosphate group, and preferred are a carboxyl group and a sulfonic acid group. These anionic groups may be partially converted into salts.

[0041] The component (B) has an anionic group of 20 to 700 (equivalents / 10 6 It may be in the range of g).

[0042] The mass ratio ((A) / (B)) of the component (A) to the component (B) may be (A) / (B)=90 / 10 to 20 / 80.

[0043] The total content of the components (A) and (B) in the first adhesive layer 5a may be 80% by mass or more, 90% by mass or more, or 95% by mass or more based on the total amount of the first adhesive layer 5a.

[0044] (Second adhesive layer) The second adhesive layer 5b contains second olefin copolymer particles having a number average particle diameter of 1 μm or less, the second olefin copolymer particles containing structural units derived from an unsaturated carboxylic acid or an anhydride thereof, and the content of the structural units is 0.01 to 5 mass % based on the total amount of the second olefin copolymer particles.

[0045] The second olefin copolymer particles may be the same as the first olefin copolymer. The second adhesive layer 5b may contain a polyester resin, as in the first adhesive layer 5a. The polyester resin may be the same as that contained in the first adhesive layer 5a. The mass ratio and total content of the second olefin copolymer particles and polyester resin in the second adhesive layer 5b may be the same as the mass ratio and total content of the (A) component and the (B) component in the first adhesive layer 5a.

[0046] (Film substrate) Examples of materials for the film substrate 7a include polyolefin film, polyethylene terephthalate film, and nylon film. The film substrate 7a is preferably a polyolefin film. By using a polyolefin film, it becomes possible to recycle the film substrate 7a together with the adhesive resin layer 3 as an olefin-based plastic material. Examples of polyolefin films include polypropylene film and polyethylene film. The film substrate 7a may be a uniaxially stretched film or a biaxially stretched film.

[0047] The thickness of the film substrate 7a is preferably 15 to 30 μm, and more preferably 18 to 20 μm, from the viewpoint of ease of processing such as lamination and ease of transportation.

[0048] (deposited layer) The deposition layer 7b is made of silicon oxide (SiO x ) is deposited on the laminate 10. This provides the laminate 10 with excellent water resistance. The thickness of the deposited layer 7b can be appropriately set depending on the intended use, but is preferably 10 to 300 nm, more preferably 30 to 300 nm, and even more preferably 30 to 100 nm. By setting the thickness of the deposited layer 7b to 10 nm or more, it is easy to ensure sufficient continuity of the deposited layer 7b, and by setting the thickness to 300 nm or less, it is possible to sufficiently suppress the occurrence of curling and cracking, and it is easy to achieve sufficient gas barrier performance and flexibility.

[0049] The deposition layer 7b is made of silicon oxide (SiO x The vapor-deposited layer 7b may be a layer obtained by vapor-depositing an inorganic oxide or metal other than aluminum oxide (AlO). x ) may be included.

[0050] The deposition layer 7b is preferably formed by a vacuum deposition method from the viewpoint of oxygen gas barrier performance and film uniformity. While known deposition methods include vacuum deposition, sputtering, and chemical vapor deposition (CVD), vacuum deposition is preferred due to its fast deposition rate and high productivity. Among vacuum deposition methods, electron beam heating is particularly effective because it allows for easy control of the deposition rate via the irradiation area and electron beam current, and allows for rapid heating and cooling of the deposition material.

[0051] In the laminate 10, the vapor deposition layer 7b is provided on only one surface of the film substrate 7a, but it is easier to maintain adhesion between the gas barrier layer 7 and the sealant layer 9 and adhesive resin layer 3 compared to when it is provided on both surfaces of the film substrate 7a.

[0052] (Overcoat layer) The overcoat layer 7c may be made of, for example, polyvinyl alcohol.

[0053] The thickness of the overcoat layer 7c may be, for example, 50 to 400 nm.

[0054] The material of the sealant layer 9 may be a resin generally used for a heat seal layer, such as branched low density polyethylene, linear low density polyethylene, polypropylene, or a copolymer resin of polyethylene and polyvinyl acetate.

[0055] The melting point of the sealant layer 9 is preferably 130°C or lower to enable low sealing temperatures and suppress foaming during heat molding. The melting point of the sealant layer 9 is preferably lower than that of the first adhesive layer 5a, as this tends to improve sealing properties during heat sealing. The melting points of the sealant layer 9 and the first adhesive layer 5a can be measured using a differential scanning calorimeter (DSC).

[0056] The thickness of the sealant layer 9 is preferably 30 to 150 μm, and more preferably 50 to 80 μm, as this provides better gas barrier properties.

[0057] (protective layer) The material of the protective layer 11 may be, for example, a polyethylene resin. When the protective layer 11 is made of a polyethylene resin, the resulting container has excellent recyclability. Polyethylene resin has high physical strength, and the resulting container has even better gas barrier properties, so medium-density polyethylene and high-density polyethylene are preferred. The thickness of the protective layer 11 is preferably 10 to 30 μm, and more preferably 15 to 20 μm, so that the resulting container has even better gas barrier properties.

[0058] Although the gas barrier laminate according to one embodiment has been described in detail above, the present invention is not limited to the above embodiment. For example, in the laminate 10, the order of lamination of the film substrate 7a, the vapor deposition layer 7b, and the overcoat layer 7c may be reversed. In the laminate 10, at least one of the vapor deposition layer 7b and the overcoat layer 7c may not be provided. In the laminate 10, the second adhesive layer 5b may not be provided.

[0059] [Method of manufacturing gas barrier laminate and raw sheet] The manufacturing method and raw sheet of the gas barrier laminate 10 according to this embodiment will be described below. The manufacturing method according to this embodiment includes the following steps. (a) A step of preparing a first raw web around which a first laminate is wound, the first laminate including a gas barrier layer, a first adhesive layer provided on a first surface of the gas barrier layer, and a second adhesive layer provided on a second surface of the gas barrier layer, with the first adhesive layer exposed on the surface. (b) A step of preparing a second roll of paper substrate. (c) A step of forming a protective layer 11 on one surface of the paper base material fed from the second roll to obtain a second laminate. (d) A process of laminating the first laminate and the second laminate while extruding an adhesive resin containing an olefin-based resin between the first adhesive layer of the first laminate fed from the first roll and the paper base material of the second laminate fed from the second roll to obtain a third laminate. (e) A step of forming a sealant layer 9 on the surface of the second adhesive layer of the third laminate to obtain a fourth laminate, and winding the obtained fourth laminate into a third web.

[0060] [(a) Process] 2 is a cross-sectional view schematically illustrating a first laminate 30 wound around a first web according to this embodiment. The first laminate 30 has a layered structure including a first adhesive layer 5a, a film substrate 7a, a vapor deposition layer 7b, an overcoat layer 7c, and a second adhesive layer 5b, in this order.

[0061] From the viewpoint of oxygen gas barrier performance and film uniformity, it is preferable to form the vapor deposition layer 7b on the surface of the film substrate 7a by vacuum deposition. While known deposition methods include vacuum deposition, sputtering, and chemical vapor deposition (CVD), vacuum deposition is preferred due to its fast deposition rate and high productivity. Among vacuum deposition methods, electron beam heating is particularly effective because it allows for easy control of the deposition rate via the irradiation area and electron beam current, and allows for rapid heating and cooling of the deposition material.

[0062] The overcoat layer 7c can be formed, for example, by wet coating the vapor deposition layer 7b using a gravure roll.

[0063] When the first adhesion layer 5a contains first olefin copolymer particles and a polyester resin, the first adhesion layer 5a may be formed, for example, by applying an aqueous dispersion obtained by mixing an aqueous dispersion of the first olefin copolymer particles and an aqueous dispersion of the polyester resin to the first surface f1 of the gas barrier layer 7 to form a coating film, and then drying the coating film. Examples of such aqueous dispersions that can be used include those described in JP 2004-9504 A. Commercially available examples of such aqueous dispersions include SB-5230N, DA-5010, and DC-5010 (all manufactured by Unitika Ltd.).

[0064] Examples of methods for applying the aqueous dispersion include direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine coating, and transfer roll coating.

[0065] The amount of the aqueous dispersion to be applied is 0.1 to 10 g / m after drying. 2 (Weight before drying: 0.4-40g / m 2 ) is preferably 1 to 3 g / m 2 (Weight before drying: 4-12g / m 2 ) is more preferable.

[0066] When the second adhesion layer 5b contains second olefin copolymer particles and a polyester resin, the second adhesion layer 5b may be formed, for example, by applying an aqueous dispersion obtained by mixing an aqueous dispersion of the second olefin copolymer particles and an aqueous dispersion of the polyester resin to the second surface f2 of the gas barrier layer 7 to form a coating film, and then drying the coating film. Such an aqueous dispersion may be the same as that used for the first adhesion layer 5a. The coating method and amount of the aqueous dispersion may be the same as those used for the first adhesion layer 5a.

[0067] [(b) Process] A second roll around which the paper base material 1 is wound is prepared.

[0068] [(c) Process] FIG. 3 is a schematic diagram showing a laminating apparatus 100 that can be used in the manufacturing method of a gas barrier laminate according to this embodiment. The laminating apparatus 100 is a three-unit type laminating apparatus having three extruders. Steps (c) to (e) will be explained below with reference to FIG. 3. A material for forming a protective layer 11 is extruded in a molten state from an extruder 103a onto one surface of the paper substrate 1 fed from the second roll 101b. The extruded material and the paper substrate 1 are sandwiched between a press roll 105a and a cooling roll 107a. This results in a second laminate in which the protective layer 11 is formed on the surface of the paper substrate 1.

[0069] The method for forming the protective layer 11 on the surface of the paper substrate 1 is not limited to extrusion lamination. Other methods include, for example, extrusion lamination, T-die extrusion molding, co-extrusion lamination, inflation, and co-extrusion inflation.

[0070] [(d) Process] An adhesive resin containing an olefin resin is extruded from an extruder 103b between the first adhesive layer 5a of the first laminate fed from the first roll and the paper base material 1 of the second laminate. The first laminate and the second laminate are sandwiched between a press roll 105b and a cooling roll 107b. This laminates the first laminate and the paper base material of the second laminate, resulting in a third laminate.

[0071] [(e) Process] A material for forming the sealant layer 9 is extruded in a molten state from an extruder 103c onto the surface of the second adhesive layer 5b of the third laminate. The extruded material and the second adhesive layer 5b are sandwiched between a press roll 105c and a cooling roll 107c. This results in a fourth laminate in which the sealant layer 9 is formed on the surface of the second adhesive layer 5b. The fourth laminate is wound up to obtain a third web 101c.

[0072] The method for forming the sealant layer 9 on the surface of the second adhesive layer 5b is not limited to extrusion lamination, but other methods include, for example, T-die extrusion molding, co-extrusion lamination, inflation, and co-extrusion inflation.

[0073] The method for producing a gas barrier laminate according to this embodiment enables efficient production of a gas barrier laminate with excellent gas barrier properties. This effect is believed to be achieved by the following mechanism. Specifically, the first and second adhesive layers contain first and second olefin copolymer particles. The first and second olefin copolymer particles contain structural units derived from an unsaturated carboxylic acid or its anhydride, and the content of these structural units is 0.01 to 5 mass% based on the total amount of the olefin copolymer particles. This improves the adhesion between the first adhesive layer and the adhesive resin containing an olefin resin, and the adhesion between the second adhesive layer and the sealant layer 9. Furthermore, the number-average particle diameter of the first olefin copolymer particles is 1 μm or less, improving the adhesion of the first adhesive layer to the adhesive resin while reducing tackiness. Because the tackiness of the first adhesive layer is reduced, the first laminate with the first adhesive layer exposed on its surface can be wound up as a raw web, eliminating the need to form an adhesive layer during the manufacturing process of bonding the first laminate to the paper substrate. Therefore, according to the method for producing a gas barrier laminate according to one aspect of the present disclosure, a gas barrier laminate with excellent gas barrier properties can be efficiently produced.

[0074] Although the manufacturing method of a gas barrier laminate and the raw web according to one embodiment have been described in detail above, the present invention is not limited to the above embodiment. For example, the first laminate wound around the first raw web may include a sealant layer 9 on the surface of the second adhesive layer 5b opposite to the surface that contacts the overcoat layer 7c. In this case, the manufacturing method of a gas barrier laminate does not need to include step (e). In this case, the laminating apparatus 100 may be a two-unit type laminating apparatus that does not include the extruder 103c, press roll 105c, and cooling roll 107c. Furthermore, in the first laminate wound around the first raw web 101a, the laminating order of the film substrate 7a, vapor deposition layer 7b, and overcoat layer 7c may be reversed. In the first laminate, at least one of the vapor deposition layer 7b and the overcoat layer 7c may be omitted. In the first laminate, the second adhesive layer 5b may be omitted. Furthermore, each layer constituting the laminate 10 may be subjected to pretreatment such as corona treatment and plasma treatment before lamination.

[0075] [container] First Embodiment The container (paper container) according to the first embodiment will be described below. A container 50 shown in FIG.

[0076] Container 50 can be used to fill and package various foods and beverages, chemical products such as adhesives and pressure sensitive adhesives, miscellaneous goods such as cosmetics and pharmaceuticals, and various other items. Because container 50 has excellent gas barrier properties, it is particularly suitable for use as a packaging container for filling and packaging liquid foods and beverages such as alcohol, dairy products such as milk, fruit drinks and other juices, mineral water, liquid seasonings such as soy sauce and sauces, and liquid foods and beverages such as curry, stew, and soup.

[0077] The container 50 is a gable-top type container. The container 50 includes a rectangular cylindrical container body 52 having an upper portion 52a with an opening 51, side surfaces 52b, and a bottom portion 52c, and a cap 55 that closes the opening 51. The container body 52 has the protective layer 11 of the laminate 10 as the outermost layer and the sealant layer 9 as the innermost layer. The container body 52 has portions where the laminate 10 is folded (folded portions B1, B2). The folded portion B1 is a portion where the laminate 10 is folded in a valley direction when viewed from the innermost layer side, while the folded portion B2 is a portion where the laminate 10 is folded in a mountain direction when viewed from the innermost layer side.

[0078] The container 50 is made of the laminate 10 that can maintain sufficient gas barrier properties even after tension is applied, and therefore, deterioration of the contents can be sufficiently suppressed for a long period of time.

[0079] Second Embodiment A container (paper container) according to the second embodiment will now be described. Unless inconsistencies arise, the points not described below are the same as those of the container according to the first embodiment. A container 60 shown in FIG. 5 is produced using the laminate 10.

[0080] The container 60 comprises a cylindrical container body 62 having an upper portion 62a with an opening 61, side surfaces 62b, and a bottom portion 62c, and a seal portion 65 that closes the opening 61. The container body 62 has the protective layer 11 of the laminate 10 as the outermost layer and the sealant layer 9 as the innermost layer. The side surfaces 62b are formed from the laminate 10 that has been bent while heat is applied.

[0081] The laminate 10 can be bent at low temperatures and is capable of maintaining sufficient gas barrier properties even after tension is applied by bending, thereby preventing deterioration of the contents for a sufficiently long period of time.

[0082] Although the container according to one embodiment has been described in detail above, the present invention is not limited to the above embodiment. For example, the container 50 has an opening 51 in the upper portion 52a, but the opening 51 does not have to be provided. Furthermore, the shape of the container is not limited to the shapes of the containers 50 and 60, and may be, for example, a brick type or a triangular pyramid type. [Example]

[0083] Hereinafter, the present disclosure will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples.

[0084] The following materials were prepared to form the adhesion layer, sealant layer, and adhesive resin layer. Aqueous dispersion A containing olefin copolymer particles: DA-5010 (product name, manufactured by Unitika Ltd.) Aqueous dispersion B containing olefin copolymer particles: SB-5230N (product name, manufactured by Unitika Ltd.) Polyethylene resin A (manufactured by Prime Polymer Co., Ltd., product name "Neozex") Ethylene-methacrylic acid copolymer resin A (manufactured by Mitsui Dow Polychemicals Co., Ltd., product name "EMAA N0908C")

[0085] [Laminate manufacturing] Example 1 A laminate according to this example was obtained through the following steps. That is, a gas barrier film was prepared in which a vapor-deposited layer (silica vapor-deposited layer, thickness: 50 nm) containing silica as the main component was formed on one surface of a film substrate (material: polypropylene resin, thickness: 18 μm). Aqueous dispersion A containing olefin copolymer particles was applied to the surface of the gas barrier film on which the vapor-deposited layer was formed, so that the weight after drying was 0.5 g / m. 2A coating film was formed by applying the coating so that the thickness of the coating film was 0.5 g / m2. The coating film was dried to form a second adhesive layer. A sealant layer (thickness: 30 μm) was formed by extrusion laminating low-density polyethylene (manufactured by Japan Polyethylene Co., Ltd., product name "LC600A") on the surface of the second adhesive layer opposite to the surface in contact with the vapor-deposited layer. An aqueous dispersion A containing olefin copolymer particles was applied to the surface of the film substrate opposite to the surface on which the vapor-deposited layer was formed, so that the weight after drying was 0.5 g / m2. 2 The coating was applied so as to form a coating film. The coating film was dried to form a first adhesive layer, and a first laminate was obtained.

[0086] On the other hand, paper base material (basis weight: 260g / m 2 A protective layer (thickness: 20 μm) made of polyethylene resin A was formed on one surface of the paper substrate, to obtain a second laminate including the paper substrate. The first and second laminates were bonded together by extrusion lamination with polyethylene resin A (adhesive resin layer) so that the first adhesive layer and the paper substrate faced each other, to obtain a gas barrier laminate (packaging material). The adhesive resin layer had a thickness of 15 μm.

[0087] Example 2 A gas barrier laminate was obtained in the same manner as in Example 1, except that aqueous dispersion B containing olefin copolymer particles was used instead of aqueous dispersion A containing olefin copolymer particles.

[0088] Example 3 A gas barrier film was prepared in the same manner as in Example 1. The surface of the gas barrier film on which the vapor deposition layer was formed was subjected to plasma treatment. A sealant layer (thickness: 30 μm) was formed on the plasma-treated surface by extrusion laminating low-density polyethylene (manufactured by Japan Polyethylene Corporation, product name "LC600A") on the surface. A first adhesive layer was formed in the same manner as in Example 1 on the surface of the film substrate opposite to the surface on which the vapor deposition layer was formed, to obtain a first laminate. A second laminate was obtained in the same manner as in Example 1. The first and second laminates were bonded together in the same manner as in Example 1 to obtain a gas barrier laminate.

[0089] (Comparative Example 1) A gas barrier film was prepared in the same manner as in Example 1. The surface of the gas barrier film on which the vapor deposition layer was formed was subjected to plasma treatment. A sealant layer (thickness: 30 μm) was formed on the plasma-treated surface by extrusion laminating low-density polyethylene (manufactured by Japan Polyethylene Corporation, product name "LC600A"), and a corona treatment was performed on the surface of the film substrate opposite to the surface on which the vapor deposition layer was formed, to obtain a first laminate. A second laminate was prepared in the same manner as in Example 1. The first and second laminates were bonded together with polyethylene resin A (adhesive resin layer) by extrusion lamination so that the film substrate and the paper substrate faced each other, to obtain a gas barrier laminate. The adhesive resin layer had a thickness of 15 μm.

[0090] (Comparative Example 2) A gas barrier film was prepared in the same manner as in Example 1. A sealant layer (thickness: 30 μm) was formed by extrusion laminating ethylene-methacrylic acid copolymer resin A onto the surface of the gas barrier film on which the vapor-deposited layer was formed, to obtain a first laminate. A second laminate was obtained in the same manner as in Example 1. The first and second laminates were bonded together by extrusion lamination with ethylene-methacrylic acid copolymer resin A (adhesive resin layer) so that the film substrate and the paper substrate faced each other, to obtain a gas barrier laminate. The adhesive resin layer had a thickness of 15 μm.

[0091] [Container manufacturing] The gas barrier laminate obtained in each Example and Comparative Example was made into a gable-top container, and heat sealing was performed by blowing hot air at 450°C onto the gas barrier laminate.

[0092] [Oxygen permeability measurement] (Examples 1 to 3 and Comparative Examples 1 and 2) An oxygen permeability measuring device (manufactured by Mocon, product name: "OX-TRAN 2 / 22") was used to measure at a temperature of 30°C and a relative humidity of 70%. Measurements were performed on containers immediately after boxing. The results are shown in Table 1. Measurement values ​​are expressed in [(cc / pkg·day)].

[0093] [Laminate strength measurement] The gas barrier laminates obtained in each Example and Comparative Example were measured for the laminate strength between the gas barrier film and the adhesive resin layer. The measurement was performed in accordance with JIS Z-1707. Specifically, the laminate was cut into 15 mm wide strips. The adhesive resin layer of the laminate cut into strips was peeled from the CPP film at a peeling rate of 300 mm / min using a Tensilon tensile tester (product name "Tensilon RTC-1250", manufactured by Orientec Co., Ltd.) so that the adhesive resin layer and the gas barrier film faced opposite directions (i.e., the peel angle was T-shaped). The strength required for peeling (unit: N / 15 mm) was measured as the laminate strength. The results are shown in Table 1.

[0094] [Presence or absence of lifting or peeling] The gas barrier laminates obtained in each of the examples and comparative examples were visually inspected for the presence or absence of lifting or peeling between layers. The results are shown in Table 1.

[0095] [Table 1] [Explanation of symbols]

[0096] 1...paper substrate, 3...adhesive resin layer, 5...adhesion layer, 7...gas barrier layer, 9...sealant layer, 10...gas barrier laminate, 11...protective layer, 50 and 60...container, 100...laminating device, 101...raw sheet.

Claims

1. preparing a first raw web around which a first laminate is wound, the first laminate including a gas barrier layer and a first adhesive layer provided on a first surface of the gas barrier layer, with the first adhesive layer exposed on a surface thereof; preparing a second roll around which a paper substrate is wound; a step of laminating the first laminate and the paper base material while extruding an adhesive resin containing an olefin-based resin between the first adhesive layer of the first laminate delivered from the first roll and the paper base material delivered from the second roll; Equipped with the first adhesive layer is formed by applying an aqueous dispersion containing first olefin copolymer particles having a number average particle diameter of 1 μm or less to form a coating film, and drying the coating film; a first olefin copolymer particle containing a structural unit derived from an unsaturated carboxylic acid or an anhydride thereof, the first olefin copolymer particle having a content of the structural unit of 0.01 to 5 mass% based on the total mass of the first olefin copolymer particle;

2. the first laminate further includes a second adhesion layer provided on the second surface of the gas barrier layer, the second adhesive layer is formed by applying an aqueous dispersion containing second olefin copolymer particles having a number average particle size of 1 μm or less to form a coating film, and drying the coating film; 2. The method for producing a gas barrier laminate according to claim 1, wherein the second olefin copolymer particles contain structural units derived from an unsaturated carboxylic acid or an anhydride thereof, and the content of the structural units is 0.01 to 5 mass% based on the total amount of the second olefin copolymer particles.

3. The method for producing a gas barrier laminate according to claim 2 , wherein the melting points of the first and second olefin copolymer particles are both 120° C. or higher.

4. 4. The method for producing a gas barrier laminate according to claim 1, wherein the gas barrier layer has a film substrate containing at least a polypropylene film and a vapor-deposited layer containing an inorganic oxide provided on a surface of the film substrate.

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