Gas barrier laminate, manufacturing method thereof, and container

Abstract

To provide a gas barrier laminate excellent in straw piercing properties, a manufacturing method thereof, and a container.SOLUTION: A gas barrier layer has a laminate structure including a protective layer, a paper substrate, an adhesive resin layer, a gas barrier layer, and a sealant layer in this order, and includes a straw piercing port where a hole penetrating the paper substrate is formed. An arithmetic average roughness Ra is 1 to 10 μm on a surface opposite to the adhesive resin layer of the protective layer at the straw piercing port.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, in the field of packaging materials, paper containers for liquids made primarily of paper have been used. Patent Document 1 discloses a paper container for liquids made by forming a box from a packaging material that includes a paper base material, a specific barrier layer, an adhesive resin layer of a specific thickness, and a heat-sealable resin layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-171649 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, paper containers are sometimes provided with a straw piercing opening for sucking out the contents with a straw. The straw piercing opening is formed by forming a hole that penetrates the paper base material.

[0005] However, when a straw piercing opening is formed in the liquid paper container disclosed in Patent Document 1, there is room for improvement in terms of ease of piercing with a straw.

[0006] In addition, it has been considered to use aluminum foil in the gas barrier layer of paper containers to improve the pierceability of the container with a straw. However, such paper containers cannot be inspected with a metal detector for foreign matter contamination. Therefore, there is a demand for packaging materials that do not use aluminum foil and have excellent pierceability with a straw. Furthermore, from the viewpoint of ease of recycling, it is desirable not to use aluminum foil. [Means for solving the problem]

[0007] The present disclosure relates to a gas barrier laminate having excellent straw pierceability, a method for producing the same, and a container.

[0008] A gas barrier laminate according to one aspect of the present disclosure has a laminated structure including, in this order, a protective layer, a paper substrate, an adhesive resin layer, a gas barrier layer, and a sealant layer, and is provided with a straw piercing opening having a hole formed therethrough, and the arithmetic mean roughness Ra of the surface of the protective layer at the straw piercing opening opposite the adhesive resin layer is 1 to 10 μm.

[0009] The gas barrier laminate according to one aspect of the present disclosure has excellent straw pierceability. This effect is believed to be achieved by the following mechanism. Specifically, when the arithmetic mean roughness Ra of the surface of the protective layer opposite the adhesive resin layer at the straw piercing opening is 1 to 10 μm, the tip of the straw easily catches on the protective layer. This makes it difficult for the straw to slip, making it easier to apply force perpendicular to the main surface of the gas barrier laminate. Furthermore, when the tip of the straw catches on the protective layer, the contact area between the gas barrier laminate and the straw decreases. This tends to increase the pressure applied to the gas barrier laminate from the tip of the straw, making the gas barrier laminate more likely to tear. As a result, the gas barrier laminate has excellent straw pierceability. Furthermore, because the gas barrier laminate according to one aspect of the present disclosure has excellent straw pierceability, it is also suitable for straws made of materials with poor strength (for example, paper straws).

[0010] The ten-point mean roughness Rz of the surface of the protective layer opposite the adhesive resin layer at the straw piercing opening may be 5 to 15 μm, as this provides better straw piercing properties. Having the ten-point mean roughness Rz within this range, i.e., having large irregularities in places on the protective layer, makes it particularly easy for the tip of a straw to get caught on these irregularities. Therefore, the gas barrier laminate provides even better straw piercing properties.

[0011] A container according to another aspect of the present disclosure is made of the gas barrier laminate. This container has excellent ease of being pierced with a straw.

[0012] A method for producing a gas barrier laminate according to yet another aspect of the present disclosure includes an extrusion lamination step in which a resin for forming a protective layer is extruded onto one surface of a paper substrate and cooled with a cooling roll to form the protective layer, and the cooling roll has an uneven roll surface. [Effects of the Invention]

[0013] According to the present disclosure, a gas barrier laminate having excellent straw pierceability, a method for producing the same, and a container are provided. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an end view schematically showing a gas barrier laminate according to an embodiment of the present disclosure. [Figure 2] FIG. 2 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 3] FIG. 3 is a perspective view schematically illustrating a container according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] [Gas barrier laminate] A gas barrier laminate (hereinafter simply referred to as "laminate") according to one embodiment will be described below. FIG. 1 is an end view schematically showing a laminate according to one embodiment. As shown in FIG. 1, a laminate 10 according to this embodiment has a laminate structure including, in this order, a protective layer 1, a paper substrate 2, an adhesive resin layer 3, a gas barrier layer 4, and a sealant layer 5. The paper substrate 2 has a hole 2a formed therethrough to serve as an opening for a straw to be inserted. The protective layer 1 is the outermost layer, and when a straw is inserted, the straw first comes into contact with the protective layer 1. The gas barrier layer 4 is made of a vapor deposition layer 4a and a film substrate 4b. Each component of the laminate 10 will be described below.

[0017] (protective layer) The material of the protective layer 1 may be, for example, a polyethylene resin. When the protective layer 1 is made of a polyethylene resin, the resulting container has excellent recyclability. Since polyethylene resin has high physical strength and the resulting container has even better gas barrier properties, medium-density polyethylene and high-density polyethylene are preferred. The density of such polyethylene resins is 0.920 g / cm 3 ~0.950g / cm 3 and preferably 0.925 g / cm 3 ~0.945g / cm 3 It is more preferable that:

[0018] The thickness of the protective layer 1 is preferably 10 to 30 μm, and more preferably 15 to 20 μm, since the resulting container will have better gas barrier properties.

[0019] The arithmetic mean roughness Ra of the surface of the protective layer 1 opposite the adhesive resin layer 3 at the straw piercing opening is 1 to 10 μm, and is preferably 2 to 8 μm, and more preferably 3 to 6 μm, as this provides better straw piercing properties.

[0020] The ten-point average roughness Rz of the surface of the protective layer 1 opposite the adhesive resin layer 3 at the straw piercing opening is preferably 5 to 15 μm, more preferably 6 to 12 μm, and even more preferably 7 to 10 μm, as this provides better straw piercing properties.

[0021] The arithmetic mean roughness Ra of the surface of the protective layer 1 opposite the adhesive resin layer 3 other than the straw piercing opening of the laminate 10 may be the same as the arithmetic mean roughness Ra at the straw piercing opening, or may be less than 1 μm or 0.5 μm or less.

[0022] The ten-point average roughness Rz of the surface of the protective layer 1 opposite the adhesive resin layer 3 other than the straw piercing opening of the laminate 10 may be the same as the ten-point average roughness Rz at the straw piercing opening, or may be less than 5 μm or 4.5 μm or less.

[0023] The arithmetic mean roughness Ra and the ten-point mean roughness Rz are measured in accordance with JIS B0601 (1994).

[0024] The protective layer 1 may contain at least one of an organic filler and an inorganic filler. It is preferable that the protective layer 1 does not contain a filler, since this provides excellent visibility to the printed layer described below.

[0025] (Paper base material) For example, paper having shapeability, flex resistance, rigidity, firmness, strength, etc. can be used as the paper substrate 2. Examples of such paper that can be used include heavily sizable bleached or unbleached paper, pure white roll paper, kraft paper, paperboard, and processed paper.

[0026] The basis weight of the paper substrate 2 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:

[0027] (adhesive resin layer) The adhesive resin layer 3 may contain at least one of a polyethylene-based resin and a polypropylene-based resin.

[0028] Examples of polyethylene-based resins include low-density polyethylene, high-density polyethylene, copolymer resins of polyethylene and polyvinyl acetate, acid anhydride-modified polyethylenes typified by terpolymers such as ethylene-ethyl acrylate-maleic anhydride, and epoxy compound-modified polyethylenes such as ethylene-glycidyl methacrylate copolymers. Low-density polyethylene is preferred because it improves pierceability. Examples of low-density polyethylene include linear low-density polyethylene and branched low-density polyethylene, with branched low-density polyethylene being preferred. Branched low-density polyethylene is preferably obtained by high-pressure radical polymerization, and more preferably obtained by homopolymerizing ethylene using high-pressure radical polymerization. Such low-density polyethylene has low mechanical strength and is more brittle than other polyolefins, resulting in good pierceability. The polyethylene-based resins may be used alone or in combination of two or more.

[0029] The density of low-density polyethylene is 0.900 g / cm 3 ~0.935g / cm 3 and preferably 0.915 g / cm 3 ~0.930g / cm 3 If the density is within the above range, the low-density polyethylene has an appropriate rigidity, and therefore the film-forming property and extrusion suitability of the adhesive resin layer 3 are improved.

[0030] The melting point of the polyethylene resin is preferably 60 to 130° C., more preferably 70 to 120° C. If the melting point is within this range, co-extrusion processability and compatibility are improved.

[0031] Examples of polypropylene-based resins include propylene homopolymers, propylene-α-olefin random copolymers, acid anhydride-modified polypropylenes such as propylene-ethyl acrylate-maleic anhydride terpolymers, and epoxy compound-modified polypropylenes such as propylene-glycidyl methacrylate copolymers. Examples of propylene-α-olefin random copolymers include propylene-ethylene copolymers, propylene-butene-1 copolymers, and propylene-ethylene-butene-1 copolymers. The polypropylene-based resin may be synthesized using a metallocene catalyst. The polypropylene-based resin is preferably a propylene-α-olefin random copolymer, and more preferably a propylene-α-olefin random copolymer polymerized using a metallocene catalyst. The use of these polypropylene-based resins improves the heat resistance of the adhesive resin layer 3 and increases its softening temperature. This makes the laminate 10 suitable for sterilization applications involving boiling or hot filling at temperatures below 100°C, or steam heating or high-pressure heating, such as retort sterilization at temperatures above 100°C. The polypropylene resins may be used alone or in combination of two or more.

[0032] The melting point of the polypropylene resin is preferably 110 to 165° C., more preferably 115 to 160° C. If the melting point is within this range, co-extrusion processability and compatibility are improved.

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

[0034] The adhesive resin layer 3 may contain at least one of an inorganic filler and an organic filler. When the adhesive resin layer 3 contains these fillers, the adhesive resin layer 3 may contain a dispersant to improve the uniformity of the dispersion of the filler.

[0035] Examples of dispersants include acid-modified polyolefins and silanol-modified polyolefins. Commercially available dispersants may be used. Examples of commercially available dispersants include Umex 1001 (manufactured by Sanyo Chemical Industries, Ltd., maleic acid-modified polypropylene).

[0036] The content of the dispersant is preferably 0.01% by mass or more, and more preferably 1% by mass or more, based on the total amount of the adhesive resin layer 3, because this makes it easy to obtain sufficient dispersibility. The content of the dispersant is preferably 20% by mass or less, and more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total amount of the adhesive resin layer 3, because this makes it easy to avoid aggregation of the inorganic filler and organic filler.

[0037] Other components than those described above may be added to the adhesive resin layer 3 as needed, such as antifogging agents, antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, release agents, UV absorbers, colorants, light stabilizers, crystal nucleating agents, plasticizers, slip agents such as fatty acid amides, dyes, pigments, release agents, and flame retardants, within the scope of the present disclosure.

[0038] The thickness of the adhesive resin layer 3 is, for example, preferably 10 to 40 μm, more preferably 15 to 25 μm. The adhesive resin layer 3 may or may not be uniaxially stretched.

[0039] (sealant layer) The sealant layer 5 contains at least one of a polyethylene-based resin and a polypropylene-based resin. The polyethylene-based resin and the polypropylene-based resin may be the same as those exemplified for the adhesive resin layer 3. The total mass of the polyethylene-based resin and the polypropylene-based resin in the sealant layer 5 may be the same as that of the adhesive resin layer 3. The sealant layer 5 may contain an inorganic filler, an organic filler, a dispersant, and other components, as in the adhesive resin layer 3. The content of the dispersant in the sealant layer 5 may be the same as that of the adhesive resin layer 3.

[0040] The thickness of the sealant layer 5 is not particularly limited, but is preferably 20 μm to 50 μm in consideration of suitability as a packaging material and processability when laminating other films or forming a vapor deposition layer.

[0041] (vapor deposited layer) The deposition layer 4a 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 4a can be appropriately set depending on the intended use, but is preferably 10 to 300 nm, and more preferably 30 to 100 nm. By setting the thickness of the deposited layer 4a to 10 nm or more, it is easy to ensure sufficient continuity of the deposited layer 4a, 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.

[0042] The deposition layer 4a is made of silicon oxide (SiO x The vapor-deposited layer 4a may be a layer obtained by vapor-depositing an inorganic oxide or metal other than aluminum oxide (AlO). x ) may be included.

[0043] (Film substrate) Examples of materials for the film substrate 4b include polyolefin film, polyethylene terephthalate film, and nylon film. The film substrate 4b is preferably a polyolefin film. By using a polyolefin film, it becomes possible to recycle the film substrate 4b together with the adhesive resin layer 3 and the sealant layer 5 as an olefin-based plastic material. Examples of polyolefin films include polypropylene film and polyethylene film. The film substrate 4b may be a uniaxially stretched film or a biaxially stretched film.

[0044] When the film substrate 4b is a polyolefin film, the laminate strength between the film substrate 4b and the sealant layer 5 is preferably 1 N / 15 mm or more, more preferably 1.5 N / 15 mm or more, and even more preferably 2 N / 15 mm or more, in order to achieve better puncture resistance. The laminate strength is measured in accordance with JIS Z-1707.

[0045] The wettability of the surface of the film substrate 4b that contacts the polyolefin film to achieve such a laminate strength may be 34 dynes or more when the laminate strength is 1 N / 15 mm or more, 36 dynes or more when the laminate strength is 1.5 N / 15 mm or more, and 38 dynes or more when the laminate strength is 2 N / 15 mm or more. The wettability is measured in accordance with JIS K6768:1999. The wettability of the surface of the film substrate 4b can be adjusted, for example, by subjecting the film substrate 4b to a corona treatment.

[0046] From the viewpoint of ease of processing such as lamination, the thickness of the film substrate 4b is preferably 15 to 30 μm, and more preferably 18 to 20 μm.

[0047] (Printing layer) The laminate 10 may further include a printed layer on the surface of the paper substrate 2 on the protective layer 1 side.

[0048] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above-described embodiments. For example, in the laminate 10, the order of lamination of the film substrate 4b and the vapor deposition layer 4a may be reversed. In this case, the laminate strength between the film substrate 4b and the adhesive resin layer 3 may be the same as the laminate strength between the film substrate 4b and the sealant layer 5 described above. The vapor deposition layer 4a may not be provided in the laminate 10.

[0049] [Method of manufacturing gas barrier laminate] A method for producing the gas barrier laminate 10 according to this embodiment will be described below. The production method according to this embodiment includes the following steps. (a) A step of preparing a first raw web around which a first laminate including a gas barrier layer is wound. (b) A step of preparing a second roll of paper substrate. (c) An extrusion lamination process in which a resin that forms a protective layer is extruded onto one surface of the paper base material fed from the second roll and cooled with a cooling roll to form a protective layer. (d) A process of laminating the first laminate and the second laminate while extruding a resin that forms an adhesive resin layer between the gas barrier layer of the first laminate delivered from the first roll and the paper base material of the second laminate delivered from the second roll to obtain a third laminate. (e) A step of forming a sealant layer on the surface of the gas barrier layer of the third laminate to obtain a fourth laminate, and winding the obtained fourth laminate into a third web.

[0050] [(a) Process] In this step, a first raw web is prepared around which a first laminate including a gas barrier layer is wound. The first laminate has a layered structure including a vapor deposition layer 4a and a film substrate 4b.

[0051] From the viewpoint of oxygen gas barrier performance and film uniformity, it is preferable to form the vapor deposition layer 4a on the surface of the film substrate 4b 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.

[0052] [(b) Process] In this step, a second roll around which the paper base material 2 is wound is prepared.

[0053] The paper substrate 2 may have a printed layer provided on the surface on which the protective layer 1 is provided in step (c). The printed layer can be formed with any desired printed pattern such as letters, figures, pictures, and symbols using a conventional printing method.

[0054] [(c) Process] FIG. 2 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. 2. A resin that will form a protective layer 1 is extruded in a molten state from an extruder 103a onto one surface of the paper substrate 2 fed from a second roll 101a. The extruded resin and the paper substrate 2 are sandwiched between a press roll 105a and a cooling roll 107a. This produces a second laminate in which the protective layer 1 is formed on the surface of the paper substrate 2.

[0055] The roll surface of the cooling roll 107a has an uneven shape. The unevenness of the roll surface results in the arithmetic mean roughness Ra of the surface of the protective layer 1 to be formed being 1 to 10 μm. Furthermore, when a printed layer is provided on the surface of the paper substrate 2 facing the protective layer 1, the unevenness of the roll surface ensures that the arithmetic mean roughness Ra of the surface of the protective layer 1 is 1 to 10 μm, thereby maintaining a certain degree of smoothness and providing excellent visibility for the printed layer. The entire roll surface may have an uneven shape, or only the portion corresponding to the straw piercing opening of the resulting laminate 10 may have an uneven shape. The arithmetic mean roughness of the uneven portion of the cooling roll 107a may be 1 to 10 μm, and is preferably 2 to 8 μm, more preferably 3 to 6 μm, since this provides the resulting laminate 10 with even better straw piercing properties.

[0056] The ten-point average roughness Rz of the portion of the cooling roll 107a having an uneven shape is preferably 5 to 15 μm, more preferably 6 to 12 μm, and even more preferably 7 to 10 μm, since the resulting laminate 10 has better straw pierceability.

[0057] The arithmetic mean roughness Ra and the ten-point mean roughness Rz are measured in accordance with JIS B0601 (1994).

[0058] [(d) Process] In this process, a resin forming the adhesive resin layer 3 is extruded in a molten state from an extruder 103b between the vapor-deposited layer 4a of the first laminate delivered from the first web and the paper base material 2 of the second laminate delivered from the second web. The first and second laminates are sandwiched between a press roll 105b and a cooling roll 107b. This laminates the vapor-deposited layer 4a of the first laminate and the paper base material 2 of the second laminate, yielding a third laminate.

[0059] [(e) Process] A material for forming the sealant layer 5 is extruded in a molten state from an extruder 103c onto the surface of the film substrate 4b of the third laminate. The extruded material and the film substrate 4b are sandwiched between a press roll 105c and a cooling roll 107c. This results in a fourth laminate in which the sealant layer 5 is formed on the surface of the film substrate 4b. The fourth laminate is wound up to obtain a third web 101c.

[0060] The method for forming the sealant layer 5 on the surface of the film substrate 4b is not limited to extrusion lamination, but other methods include, for example, T-die extrusion molding, co-extrusion lamination, inflation, and co-extrusion inflation.

[0061] Although the method for producing a 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, the first laminate wound around the first web may include a sealant layer 5 on the surface of the film substrate 4b. In this case, the method for producing 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 web 101a, the laminating order of the vapor deposition layer 4a and the film substrate 4b may be reversed. The first laminate may not have a vapor deposition layer 4a. Furthermore, each layer constituting the laminate 10 may be subjected to pretreatment such as corona treatment and plasma treatment before lamination.

[0062] In step (c), the roll surface of the cooling roll 107a may not have an irregular shape. In this case, the method for producing a gas barrier laminate may further include a step of sandwiching the fourth laminate between an embossing roll having an irregular shape and a press roll. In this case, the arithmetic mean roughness Ra and ten-point mean roughness Rz of the surfaces of the embossing roll and the press plate may be the same as those of the cooling roll. In addition, when the surface of the cooling roll 107a does not have an irregular shape, the method for producing a gas barrier laminate may further include a step of sandblasting the surface of the protective layer 1. By including such a step, the arithmetic mean roughness Ra of the surface of the protective layer 1 can be set to 1 to 10 μm ... include blending at least one of an organic filler and an inorganic filler into the protective layer 1 to set the arithmetic mean roughness Ra of the surface of the protective layer 1 to 10 μm.

[0063] [container] The container (paper container) according to this embodiment will be described below. A container 50 shown in FIG.

[0064] 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. Container 50 has excellent pierceability and gas barrier properties, making it 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.

[0065] The container 50 is a brick-type container. The container 50 has a rectangular parallelepiped container body 52 having an upper portion 52a with a straw piercing opening 51, side surfaces 52b, and a bottom portion 52c. The straw piercing opening 51 is a portion of the laminate 10 where a hole 2a is formed in the paper base material 2.

[0066] Although the container according to the present embodiment has been described in detail above, the container according to the present invention is not limited to the above embodiment. For example, the shape of the container is not limited to the shape of container 50, and may be, for example, a gable top type or a triangular pyramid shape. Furthermore, the shape of the container body may be cylindrical. [Example]

[0067] 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.

[0068] [Laminate manufacturing] Example 1 The laminate according to this example was obtained through the following steps. That is, a gas barrier film was prepared in which a vapor deposition layer (silica vapor deposition 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). The surface of the film substrate opposite to the surface on which the vapor deposition layer was formed was subjected to corona treatment so that the surface wettability was 40 dynes. A sealant layer (material: density 0.918 g / cm 3 ) was formed by extrusion lamination on the surface of the film substrate opposite to the surface on which the vapor deposition layer was formed. 3 A low density polyethylene sheet (thickness: 30 μm) was formed to obtain an inner layer material.

[0069] On the other hand, a paper substrate (basis weight: 260 g / m) with a hole for piercing the straw was used. 2 A protective layer (thickness: 20 μm) was formed on one surface of the paper substrate to obtain an outer layer material containing a paper substrate. The protective layer was formed using medium-density polyethylene (density: 0.930 g / cm 3 ) was extruded onto one side of a paper substrate and cooled with cooling roll A (arithmetic mean roughness of the roll surface Ra: 2.1 μm, ten-point mean roughness Rz: 8.2 μm) having an uneven surface.

[0070] The inner and outer layers are bonded by extrusion lamination so that the vapor-deposited layer of the inner layer and the paper substrate of the outer layer face each other. 3The laminate was obtained by laminating the laminate with a low-density polyethylene sheet (thickness: 15 μm).

[0071] Example 2 A laminate was obtained in the same manner as in Example 1, except that cooling roll B (arithmetic mean roughness of roll surface Ra: 4.2 μm, ten-point mean roughness Rz: 8.6 μm) was used instead of cooling roll A.

[0072] Example 3 A laminate was obtained in the same manner as in Example 1, except that cooling roll C (arithmetic mean roughness of roll surface Ra: 1.4 μm, ten-point mean roughness Rz: 9.3 μm) was used instead of cooling roll A.

[0073] (Comparative Example 1) A laminate was obtained in the same manner as in Example 1, except that cooling roll D (arithmetic mean roughness of roll surface Ra: 0.15 μm, ten-point mean roughness Rz: 0.63 μm) was used instead of cooling roll A.

[0074] [Measurement of arithmetic mean roughness and ten-point mean roughness] For the laminates obtained in each example and comparative example, the arithmetic mean roughness Ra and ten-point mean roughness Rz of the surface of the protective layer at the straw piercing opening were measured using a surface roughness measuring device (manufactured by Tokyo Seimitsu, product name: SURFCOM TOUCH50). The measurements were performed in accordance with JIS B0601 (1994). The results are shown in Table 1.

[0075] [Puncture resistance] The pierceability of the laminates obtained in each of the Examples and Comparative Examples was evaluated in the following manners 1 and 2. The results are shown in Table 1.

[0076] <Rating 1> A straw (tip angle: 45°, material: plastic) was attached to a push-pull gauge (manufactured by Imada Co., Ltd., product name: "DPX-5T"). The straw was pierced from the protective layer side of the straw piercing opening of the laminate, and the peak load value measured until the laminate broke was used. The straw piercing speed was 1 m / s. The same person performed the evaluation. Measurements were performed on 10 laminates. The minimum and maximum values ​​of the measurements obtained from the 10 laminates, as well as the average value of the measurements obtained from the 10 laminates, are shown in Table 1. A smaller maximum value indicates better pierceability.

[0077] <Rating 2> A straw (tip angle: 45°, material: plastic) was attached to a push-pull gauge (manufactured by Imada Co., Ltd., product name: "DPX-5T"). The straw was pierced from the protective layer side of the straw piercing opening of the laminate. The evaluation was performed by the same person. The piercing property was evaluated based on the following criteria. 2: There is no slippage when inserting the straw, so it is not difficult to insert. 1: When inserting the straw, it becomes slippery and difficult to insert.

[0078] [Table 1]

[0079] In Evaluation 2 of pierceability, in Examples 1 to 3, the straw did not slip when piercing, and the straw pierced perpendicularly to the main surface of the laminate. On the other hand, in Comparative Example 1, the straw slipped when piercing. As a result, the applied force was shifted from the direction perpendicular to the main surface of the laminate, and the straw did not pierce perpendicularly. [Explanation of symbols]

[0080] 1...protective layer, 2...paper base material, 2a...hole, 3...adhesive resin layer, 4...gas barrier layer, 5...sealant layer, 10...laminated body, 50...container, 51...straw piercing opening, 107a...cooling roll.

Claims

1. A protective layer; A paper substrate; an adhesive resin layer; a gas barrier layer; a sealant layer; in this order, A straw piercing opening is provided with a hole penetrating the paper substrate, The gas barrier laminate has an arithmetic mean roughness Ra of 1 to 10 μm on the surface of the protective layer opposite to the adhesive resin layer at the straw piercing opening.

2. 2. The gas barrier laminate according to claim 1, wherein the ten-point average roughness Rz of the surface of the protective layer opposite to the adhesive resin layer at the straw piercing opening is 5 to 15 μm.

3. A gas barrier laminate as described in claim 1, wherein the gas barrier layer consists of a vapor deposition layer and a film substrate.

4. A container formed from the gas barrier laminate according to claim 1 or 2.

5. A method for producing the gas barrier laminate according to claim 1 or 2, comprising: an extrusion lamination process in which a resin that forms the protective layer is extruded onto one surface of the paper base material and cooled with a cooling roll to form the protective layer; The method for producing a gas barrier laminate, wherein the cooling roll has an uneven surface.

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