Laminate and container

Abstract

To reduce the infiltration of an adhesion layer to a paper substrate layer within a container, where the paper substrate layer and a resin substrate layer are bonded using the adhesion layer; thereby enabling, for example, easier separation of the resin material from the paper material after use.SOLUTION: A laminate includes: a resin substrate layer that contains at least polyolefin resin and has a thickness of 70 μm or more; and an adhesion layer that can bond the resin substrate layer to a paper substrate layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a laminate and a container. [Background technology]

[0002] A container is known that combines a paper material with a resin material that adheres to the paper material, thereby achieving durability and airtightness (moisture resistance) that cannot be achieved with paper material alone, while reducing the amount of resin used by making the resin material thinner. As an example of such technology, Patent Document 1 describes a technology related to a paper container that is suitable for microwave heating and can be manufactured efficiently. The paper container has a container body formed by folding a sheet material. The sheet material has a paper substrate, an anchor layer formed on the substrate, and a sealant layer formed on the anchor layer with a thickness of 20 μm or more and less than 60 μm, where the anchor layer is formed from an aqueous dispersion of acid-modified polypropylene resin. The melting point of the polypropylene contained in the aqueous dispersion of acid-modified polypropylene resin is 120°C or higher. The sealant layer is formed from homopolypropylene with a melting point of 135°C or higher. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-26291 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of the above-mentioned containers, it is preferable to separate the paper material and the resin material after use and dispose of them from the viewpoint of recycling and waste treatment. However, when peeling the paper material from the resin material, the adhesive layer on the resin material side impregnates the paper material, and the adhesive strength is too high, so the paper material is destroyed during peeling, making separation difficult in some cases.

[0005] Therefore, the present invention aims to provide a laminate and a container in which a paper base layer and a resin base layer are bonded together using an adhesive layer, and which can easily separate the resin material and the paper material, for example, after use, by reducing the impregnation of the adhesive layer into the paper base layer. [Means for solving the problem]

[0006] [1] A laminate comprising a resin substrate layer containing at least a polyolefin resin and having a thickness of 70 μm or more, and an adhesive layer capable of adhering the resin substrate layer to a paper substrate layer. [2] The laminate according to [1], wherein the resin substrate layer has a thickness of 1500 μm or less. [3] The laminate according to [1] or [2], wherein the thickness of the adhesive layer is 3 μm or more and 200 μm or less. [4] The laminate according to any one of [1] to [3], wherein the adhesive layer has a melt flow rate of 80 g / 10 min or less. [5] A laminate according to any one of [1] to [4], wherein the adhesive layer contains one or more components selected from the group consisting of an acid-modified polyolefin resin, a pressure-sensitive adhesive, and a tackifying resin. [6] The laminate according to any one of [1] to [5], wherein the adhesive layer contains acid-modified polyethylene. [7] The laminate according to any one of [1] to [6], wherein the melt flow rate ratio of the adhesive layer to the melt flow rate of the resin substrate layer is 80 or less. [8] The laminate according to any one of [1] to [7], wherein the peel strength between the resin substrate layer and the adhesive layer is 1.0 kgf / 15 mm or more. [9] The laminate according to any one of [1] to [8], wherein the resin substrate layer includes a surface layer, a first substrate layer, and the adhesive layer in this order.

[10] The laminate described in any one of [1] to [8], wherein the resin substrate layer includes, in this order, a surface layer, a first substrate layer, an oxygen barrier layer and a pair of barrier adhesive layers laminated on both sides of the oxygen barrier layer, and a second substrate layer.

[11] The Martens hardness of the adhesive layer when the temperature is 30°C is 0.1 N / mm 2 More than 50N / mm 2 The laminate according to any one of [1] to

[10] , which is:

[12] The Martens hardness of the adhesive layer when the temperature is 110°C is 0.01 N / mm 2 More than 20N / mm 2 The laminate according to any one of [1] to

[11] , which is:

[13] A container comprising a container body having a shape including a recess and a flange portion formed along the periphery of the recess and extending outward from the periphery, the container body including the laminate described in any one of [1] to

[12] and the paper base layer adhered to the adhesive layer.

[14] The container described in

[13] , wherein the container body is formed by adhering the laminate to the paper base layer formed into a shape including the recess and the flange portion with the adhesive layer.

[15] A container comprising a container body having a shape including a recess and a flange portion formed along the periphery of the recess and extending outward from the periphery, the container body including a resin substrate layer having a thickness of 70 μm or more, a paper substrate layer, and an adhesive layer that bonds the resin substrate layer to the paper substrate layer, the container body including a recess and a flange portion that extends outward from the periphery.

[16] A container described in any one of

[13] to

[15] , further comprising a lid body that is joined to the container body at a joining region formed in the flange portion to form an internal space between the lid body and the recess.

[17] The container described in

[16] , wherein the peel strength between the adhesive layer and the paper base layer is higher than the peel strength between the container body and the lid.

[18] The container according to any one of

[13] to

[17] , wherein the peel strength between the adhesive layer and the paper base layer is 0.01 kgf / 15 mm or more and 10.0 kgf / 15 mm or less. [Effects of the Invention]

[0007] According to the above configuration, in a container in which a paper base layer and a resin base layer are bonded using an adhesive layer, by reducing the impregnation of the adhesive layer into the paper base layer, the resin material and the paper material can be easily separated, for example, after use. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of a container according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing the configuration of a laminate according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a first configuration example of a resin substrate layer in the laminate shown in FIG. 2. [Figure 4] 3 is a schematic cross-sectional view showing a second configuration example of a resin substrate layer in the laminate shown in FIG. 2. FIG. [Figure 5] FIG. 10 is a schematic cross-sectional view showing another example of the second configuration example. [Figure 6] 10A to 10C are diagrams illustrating a manufacturing process of a laminate according to a second configuration example. [Figure 7] FIG. 2 is a schematic cross-sectional view showing a first configuration example for opening a container. [Figure 8] 8A to 8C are diagrams illustrating a method for forming a resin reservoir portion of the container shown in FIG. 7. [Figure 9] FIG. 10 is a schematic cross-sectional view showing a second configuration example for opening a container. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 is a schematic cross-sectional view showing the configuration of a container according to one embodiment of the present invention. The container 1 includes a container body 2, which includes a laminate 10 and a paper substrate layer 20 (described below), and a lid 3. The container body 2 has a shape including a recess 2A and a flange 2B formed along the periphery of the recess 2A and extending outward from the periphery of the recess 2A. The lid 3 is joined to the container body 2 at a joining region 4 formed in the flange 2B by, for example, heat sealing, thereby forming an internal space SP between the lid 3 and the recess 2A. In the illustrated example, the container body 2 is formed so that the resin substrate layer 100 included in the laminate 10 faces the internal space SP, and the paper substrate layer 20 faces the external side. As described below, the resin substrate layer 100 and the paper substrate layer 20 are bonded together by an adhesive layer 200.

[0010] In the container 1 described above, it is preferable that the peel strength between the adhesive layer 200 and the paper base layer 20 is higher than the opening strength between the container body 2 and the lid body 3 so that the adhesive layer 200 does not peel off from the paper base layer 20 when the lid body 3 is peeled off from the container body 2 to open it.

[0011] Specifically, the peel strength between the adhesive layer 200 and the paper substrate layer 20 is preferably 0.01 kgf / 15 mm or more, more preferably 0.03 kgf / 15 mm or more, and even more preferably 0.05 kgf / 15 mm or more. Furthermore, from the viewpoint of easily peeling the resin substrate layer 100 and the paper substrate layer 20 after use of the container 1, the peel strength between the adhesive layer 200 and the paper substrate layer 20 is preferably 10.0 kgf / 15 mm or less, more preferably 3.0 kgf / 15 mm or less, even more preferably 2.5 kgf / 15 mm or less, and particularly preferably 2.0 kgf / 15 mm or less. Here, the peel strength also includes the strength when the adhesive layer 200 partially remains on the paper substrate layer 20 upon peeling. In other words, the peel strength is not limited to the strength when the adhesive layer 200 and the paper substrate layer 20 peel at the interface before bonding.

[0012] On the other hand, the peel strength between the surface layer of the laminate 10 and the lid 3 is preferably 0.01 kgf / 15 mm or more, and more preferably 0.05 kgf / 15 mm or more. The peel strength between the surface layer of the laminate 10 and the lid 3 is preferably 5.0 kgf / 15 mm or less, more preferably 2.0 kgf / 15 mm or less, and even more preferably 1.5 kgf / 15 mm or less. Here, the peel strength also includes the strength when cohesive failure occurs in the surface layer upon opening. In other words, the peel strength is not limited to the strength when the surface layer of the laminate 10 and the lid 3 peel at the interface before bonding.

[0013] FIG. 2 is a schematic cross-sectional view showing the configuration of a laminate according to one embodiment of the present invention. In this embodiment, the laminate 10 is in the form of a sheet. The laminate 10 includes a resin substrate layer 100 and an adhesive layer 200. The laminate 10 is adhered to a paper substrate layer 20 by the adhesive layer 200 to form a composite laminate 30 as shown in FIG. 1. Here, the laminate 10 can be manufactured and distributed independently of the paper substrate layer 20, and the paper substrate layer 20 can be adhered to the laminate 10 later, as shown in FIG. 2. In other words, the adhesive layer 200 in the laminate 10 is configured to allow the resin substrate layer 100 to be adhered to the paper substrate layer 20.

[0014] Such adhesive layer 200 may contain one or more components selected from the group consisting of acid-modified polyolefin resins, pressure-sensitive adhesives, thermoplastic elastomers, and tackifier resins, as exemplified below. More specifically, for example, adhesive layer 200 may contain one or more components selected from the group consisting of acid-modified polyolefin resins such as acid-modified polyethylene or acid-modified polypropylene, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers, ethylene-acrylic acid resins, ethylene-methyl acrylate-maleic anhydride copolymers, ethylene-vinyl acetate-maleic anhydride terpolymers, ethylene-acrylic acid ester-maleic anhydride terpolymers, ethylene-acrylic acid ester-glycidyl methacrylate terpolymers, ethylene glycidyl methacrylate copolymers, and ethylene-vinyl acetate copolymers. Additionally or alternatively, adhesive layer 200 may contain acid-modified polyolefin resins other than those exemplified above.

[0015] The adhesive layer 200 may contain a pressure-sensitive adhesive, for example, one or more pressure-sensitive adhesives selected from the group consisting of polyolefin-based, EVA-based, acrylic-based, synthetic rubber-based, ester-based, amide-based, and urethane-based adhesives, either alone or in any combination thereof. In addition to or instead of these, the adhesive layer 200 may contain a pressure-sensitive adhesive other than those exemplified above.

[0016] The adhesive layer 200 may contain, for example, one or more thermoplastic elastomers selected from the group consisting of olefins, styrenes, esters, amides, and urethanes, either alone or as a mixture of any combination thereof, or may contain low-density polyethylene including high-pressure low-density polyethylene or linear metallocene low-density polyethylene (C4, C6, C8), etc. In addition to or instead of these, the adhesive layer 200 may contain a thermoplastic elastomer or low-density polyethylene other than those exemplified above.

[0017] In addition to the pressure-sensitive adhesive, thermoplastic elastomer, or polyolefin resin contained in the adhesive layer 200, tackifying resins such as petroleum-based resins including aliphatic copolymers, aromatic copolymers, aliphatic-aromatic copolymers, or alicyclic copolymers, coumarone-indene resins, terpene resins, terpene-phenol resins, or rosin-based resins including polymerized rosin, (alkyl)phenol resins, xylene resins, or hydrogenated versions of these may be used in combination. These tackifying agents may be used alone or in combination of two or more. The adhesive layer 200 may also contain additives such as softeners such as liquid polymers or paraffin oil, fillers, pigments, antioxidants, stabilizers, or UV absorbers. The adhesive layer 200 can also be formed by using the tackifying resin alone without using the pressure-sensitive adhesive. In addition to or instead of these, the adhesive layer 200 may contain tackifying resins or additives other than those exemplified above.

[0018] The adhesive layer 200 is made of a material selected from the group consisting of an acid-modified polyolefin resin such as acid-modified polyethylene or acid-modified polypropylene, an ethylene-methyl methacrylate copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-butyl acrylate copolymer, an ethylene-acrylic acid resin, an ethylene-methyl acrylate-maleic anhydride copolymer, an ethylene-vinyl acetate-maleic anhydride terpolymer, an ethylene-acrylic acid ester-maleic anhydride terpolymer, an ethylene acrylic acid ester-glycidyl methacrylate terpolymer, an ethylene glycidyl methacrylate copolymer, and an ethylene vinyl acetate copolymer. The adhesive may contain any of the above components, and may contain one or more adhesives selected from the group consisting of polyolefin-based, EVA-based, acrylic-based, synthetic rubber-based, ester-based, amide-based, and urethane-based adhesives, either alone or as a mixture of any combination thereof. It is preferable that the adhesive contains, as the tackifying resin, one or more of petroleum-based resins including aliphatic copolymers, aromatic copolymers, aliphatic-aromatic copolymers, or alicyclic copolymers; coumarone-indene-based resins, terpene-based resins, terpene-phenol-based resins, or rosin-based resins including polymerized rosin; (alkyl)phenol-based resins; xylene-based resins; and hydrogenated versions of these.

[0019] Regarding the resins exemplified above, adhesive layer 200 may contain two or more types of the same resin but with different formulations or physical properties. For example, in the case of acid-modified polyethylene, adhesive layer 200 may contain two or more types of acid-modified polyethylene that differ in density, MFR, degree of acid modification, molecular weight, etc.

[0020] Furthermore, from the viewpoint of adjusting the peel strength, the adhesive layer 200 preferably contains 1% or more and 99% or less of a polyolefin resin. The type of polyolefin resin is not particularly limited, but may be, for example, a polypropylene-based resin or a polyethylene-based resin, or a mixture thereof. The polypropylene-based resin is a polymer containing at least propylene, such as homopolypropylene or a copolymer of propylene and an olefin. The copolymer of propylene and an olefin is a block copolymer, a random copolymer, or a mixture thereof. The polyethylene-based resin is a polymer containing at least ethylene, such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear ethylene-α-olefin copolymer, or ethylene-1-hexene copolymer.

[0021] The adhesive layer 200 may be one that allows the paper container and the sheet to be peeled off by adding a foaming agent or the like to the inside to cause cohesive failure of the adhesive layer itself. Examples of foaming agents that can be added to the adhesive layer 200 include inorganic chemical foaming agents and organic chemical foaming agents.

[0022] The adhesive layer 200 may be a single layer or may have two or more layers. When the adhesive layer 200 has two or more layers, for example, each layer may individually contain the components exemplified above.

[0023] The container body 2 may be formed, for example, by forming the paper base layer 20 into a shape including the recess 2A and the flange 2B, and then bonding the laminate 10 to the paper base layer 20 with an adhesive layer 200. Alternatively, the composite laminate 30, in which the laminate 10 is bonded to the paper base layer 20 with the adhesive layer 200, may be formed into a shape including the recess 2A and the flange 2B. The compressed air pressure when bonding the laminate 10 to the paper base layer 20 is preferably 0.5 MPa or less, and more preferably 0.3 MPa or less. There is no particular lower limit to the compressed air pressure, but it is, for example, 0 or more.

[0024] In this embodiment, the resin substrate layer 100 of the laminate 10 contains at least a polyolefin resin and has a thickness of 70 μm or more. This configuration reduces impregnation of the adhesive layer 200 into the paper substrate layer 20 when the laminate 10 is adhered to the paper substrate layer 20. Therefore, in this embodiment, the adhesive strength between the adhesive layer 200 and the paper substrate layer 20 is kept within an appropriate range for use as, for example, the container body 2 described above, and after use, the resin material of the laminate 10 and the paper material of the paper substrate layer 20 can be easily separated. The thickness of the resin substrate layer 100 is preferably 80 μm or more, more preferably 90 μm or more, and even more preferably 100 μm or more.

[0025] From the viewpoint of realizing stable adhesion, the thickness of the adhesive layer 200 is, for example, 3 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. From the viewpoint of reducing the amount of resin used by utilizing a paper material, the thickness of the resin substrate layer 100 is, for example, 500 μm or less, preferably 390 μm or less, more preferably 370 μm or less, and even more preferably 350 μm or less. From the same viewpoint, the thickness of the adhesive layer 200 is, for example, 100 μm or less, preferably 80 μm or less, more preferably 70 μm or less, and even more preferably 60 μm or less. Meanwhile, the square meter weight of the paper substrate layer 20 is, for example, 100 g / m 2 or more, preferably 150 g / m 2 More preferably, it is 200 g / m or more. 2 The square meter weight of the paper base layer 20 is, for example, 500 g / m 2 and preferably 450 g / m 2 More preferably, it is 400 g / m or less. 2 The density of the paper base layer 20 is, for example, 1.0×10 3 g / m 3 or more, preferably 1.0 × 10 4 g / m 3 or more, preferably 7.0 × 10 5 g / m 3 More preferably, 8.0×105 g / m 3 More preferably, it is 8.5×10 5 g / m 3 The upper limit is not particularly limited, but is, for example, 1.0 × 10 9 g / m 3 The following is the result.

[0026] The paper substrate layer may be paper alone, or the adhesive surface to the sheet may be coated with, for example, a resin such as low-density polyethylene, or an inorganic substance such as calcium carbonate, talc, or zeolite.

[0027] The melt flow rate of the adhesive layer 200 is preferably 80 g / 10 min or less, more preferably 37 g / 10 min or less, and even more preferably 35 g / 10 min or less. There is no particular limitation on the lower limit, but it may be, for example, 0 g / 10 min. Herein, unless otherwise specified, the melt flow rate is measured in accordance with JIS K7210-1 under a load of 2.16 kg. The measurement temperature is 190°C for the adhesive layer 200 and 230°C for the resin substrate layer 100. The melt flow rate ratio of the adhesive layer 200, where the melt flow rate of the resin substrate layer 100 is taken as 1, is preferably 80 or less, more preferably 70 or less, and even more preferably 60 or less. There is no particular limitation on the lower limit, but it may be, for example, 0.01. When the resin substrate layer 100 includes multiple layers, the melt flow rate of the resin substrate layer 100 refers to the melt flow rate of the layer closest to the adhesive layer 200. The peel strength between the resin substrate layer 100 and the adhesive layer 200 is preferably higher than the peel strength between the adhesive layer 200 and the paper substrate layer 20. More specifically, the peel strength between the resin substrate layer 100 and the adhesive layer 200 is desirably 1.0 kgf / 15 mm or more, preferably 1.2 kgf / 15 mm or more, more preferably 1.4 kgf / 15 mm or more, even more preferably 2.0 kgf / 15 mm or more, even more preferably 5.0 kgf / 15 mm or more, and particularly preferably more than 10.0 kgf / 15 mm. There is no particular upper limit, but it is, for example, 100 kgf / 15 mm.

[0028] Furthermore, from the viewpoint of adjusting the peel strength, it is preferable to adjust the rigidity of the adhesive layer 200. Martens hardness is used as an index of rigidity. When the temperature of the adhesive layer is 30°C, the Martens hardness is 50 N / mm 2 Less than 20N / mm is preferable 2 Less than 10N / mm is more preferable. 2 Less than 8N / mm is more preferable. 2 Even more preferably, 7N / mm 2 The following is particularly preferred: the Martens hardness when the temperature of the adhesive layer is 110°C is 20 N / mm 2 Less than 5N / mm is preferable 2 Less than 2N / mm is more preferable. 2 More preferably, 1.4 N / mm 2 On the other hand, the Martens hardness when the temperature of the adhesive layer is 30°C is more preferably 0.1 N / mm 2 More than 1.0N / mm is preferable. 2 More preferably, 4.0N / mm 2 More preferably, 5.0N / mm 2 The above is even more preferable. Similarly, from the viewpoint of peelability, the Martens hardness when the temperature of the adhesive layer is 110°C is 0.01 N / mm 2 More than 0.1N / mm is preferable. 2 More preferably, 0.5N / mm 2 More preferably, 1.0 N / mm 2 The above is even more preferable.

[0029] In particular, when the adhesive layer 200 contains an ethylene vinyl acetate (EVA)-based adhesive, the melt flow rate of the adhesive layer 200 is preferably 0.1 g / 10 min or more, more preferably 0.2 g / 10 min or more, even more preferably 0.3 g / 10 min or more, and particularly preferably 0.5 g / 10 min or more. Furthermore, when the adhesive layer 200 contains an EVA-based adhesive, the melt flow rate of the adhesive layer 200 is preferably 80 g / 10 min or less, more preferably 20 g / 10 min or less, even more preferably 12 g / 10 min or less, and particularly preferably 4.7 g / 10 min or less. Setting the melt flow rate within this range allows for cleaner interfacial peeling between the paper substrate and the sheet, improving the recyclability of the container 1.

[0030] The adhesive layer 200 may contain one type of EVA-based adhesive, or two or more types of EVA-based adhesives may be mixed to adjust the melt flow rate. When two or more types of EVA-based adhesives are mixed, it is preferable to mix at least one of an adhesive having a melt flow rate of 3.0 g / 10 min or less and an adhesive having a melt flow rate of 7.0 g / 10 min or more, and it is more preferable to mix both an adhesive having a melt flow rate of 3.0 g / 10 min or less and an adhesive having a melt flow rate of 7.0 g / 10 min or more.

[0031] Furthermore, from the viewpoint of adjusting the peel strength, the adhesive layer 200 may contain, in addition to the EVA-based adhesive, for example, an ethylene-1-hexene copolymer of a polyethylene-based resin. In this case, the content of the EVA-based adhesive in the adhesive layer 200 is preferably 99% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less. In addition, in the above case, the content of the EVA-based adhesive in the adhesive layer 200 is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more. Meanwhile, in the above case, the content of the ethylene-1-hexene copolymer in the adhesive layer 200 is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 15% by mass or more. In addition, in the above case, the content of ethylene-1-hexene copolymer in adhesive layer 200 is preferably 99% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0032] (Configuration example of resin substrate layer) Below, a description will be given of an example configuration of the resin substrate layer 100 in the laminate 10 described with reference to Fig. 2. When the resin substrate layer 100 includes multiple layers, it is sufficient that at least one of the multiple layers contains a polyolefin resin, and the total thickness of the multiple layers is 70 µm or more. Note that the configuration of the resin substrate layer 100 is not limited to the example described below, and various configurations known as resin laminates can be used.

[0033] The type of polyolefin-based resin contained in the resin substrate layer 100 is not particularly limited, and may be, for example, either a polypropylene-based resin or a polyethylene-based resin, or a mixture thereof. The polypropylene-based resin is a polymer containing at least propylene, such as homopolypropylene or a copolymer of propylene and an olefin. The copolymer of propylene and an olefin is a block copolymer, a random copolymer, or a mixture thereof. The polyethylene-based resin is a polymer containing at least ethylene, such as high-density polyethylene, low-density polyethylene, linear low-density polyethylene, or linear ethylene-α-olefin copolymer. The polypropylene-based resin and polyethylene-based resin may be composed of one of the various polypropylene-based resins and polyethylene-based resins exemplified above, or two or more of them may be used in combination.

[0034] By using a polypropylene-based resin as the main component of the resin substrate layer 100, specifically a component that accounts for 50% by mass or more, the heat resistance of the laminate 10 can be improved, making the container 1 suitable for reheating in the microwave. Furthermore, by further including an inorganic substance such as talc in the resin substrate layer 100, the difference in thermal shrinkage rate between the laminate 10 and the paper substrate layer 20 becomes smaller when the composite laminate 30 is thermoformed into the shape of the container body 2, and deformation of the container 1 can be reduced.

[0035] Furthermore, in at least one layer included in the resin substrate layer 100, at least a portion of the polyethylene-based resin may be a biomass-derived polyethylene-based resin (biopolyethylene). Examples of biopolyethylene materials include corn, cassava, sugarcane, sugar beet, palm, soybean, and castor bean. Biopolyethylene may be produced by any method, such as fermentation, bacterial fermentation, chemical reaction, or culture extraction. Furthermore, in at least one layer included in the resin substrate layer 100, at least a portion of the polypropylene-based resin may be a biomass-derived polypropylene-based resin (biopolypropylene). Biopolypropylene can be obtained, for example, by fermenting the molasses of sorghum, a non-edible plant, with microorganisms to produce an intermediate material, which is then dehydrated.

[0036] The laminate according to the embodiment of the present invention has, for example, the following layer configurations (1) to (10). (1) First substrate layer / adhesive layer (2) Second substrate layer / first substrate layer / adhesive layer (3) Second substrate layer / first substrate layer / first substrate layer / second substrate layer / adhesive layer (4) Second substrate layer / first substrate layer / barrier adhesive layer / oxygen barrier layer / barrier adhesive layer / first substrate layer / adhesive layer (5) Surface layer / first substrate layer / adhesive layer (6) Surface layer / second substrate layer / first substrate layer / adhesive layer (7) Surface layer / second substrate layer / first substrate layer / first substrate layer / second substrate layer / adhesive layer (8) Surface layer / second substrate layer / first substrate layer / barrier adhesive layer / oxygen barrier layer / barrier adhesive layer / first substrate layer / adhesive layer (9) Surface layer / first substrate layer / barrier adhesive layer / oxygen barrier layer / barrier adhesive layer / first substrate layer / second substrate layer / adhesive layer (10) Surface layer / first substrate layer / barrier adhesive layer / oxygen barrier layer / barrier adhesive layer / first substrate layer / adhesive layer

[0037] Specific examples of the layer configurations described above are further described below. Note that the "first substrate layer" and the "second substrate layer" in each example do not mean the same layer, but are defined independently in each example to distinguish between multiple substrate layers.

[0038] FIG. 3 is a schematic cross-sectional view showing a first configuration example of the resin substrate layer in the laminate shown in FIG. In the illustrated example, the resin substrate layer 100 includes, in this order, a surface layer 101, substrate layers 114 and 113 (first substrate layers), an oxygen barrier layer 111, a pair of barrier adhesive layers 112 laminated on both sides of the oxygen barrier layer 111, and single-layer or multi-layer substrate layers 113 and 114 (second substrate layers). The resin substrate layer 100 may include additional layers or omit any of the layers depending on, for example, the required rigidity and barrier properties. Specifically, the substrate layers 113 and 114 (first and second substrate layers), which are exemplified above as two layers, may be one layer or three or more layers. Alternatively, the substrate layers 113 and 114 may be formed from the same resin composition. The following describes in more detail exemplary configurations of each layer.

[0039] The oxygen barrier layer 111 is a barrier layer containing, for example, an ethylene vinyl alcohol resin such as ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride, Mx nylon (MxNy), or polyacrylonitrile. The thickness of the oxygen barrier layer 111 is, for example, 0.1% to 15% of the entire laminate 10. The barrier adhesive layer 112 is formed of, for example, a urethane-based elastomer, a styrene-based elastomer, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, or EVA.

[0040] The base layers 113 and 114 are formed of a resin composition containing a polyolefin resin. In addition to the polyolefin resin, the base layers 113 and 114 may further contain additive materials such as a polystyrene resin, a polyester resin, or a mixture thereof, an inorganic substance such as talc, an elastomer, or a petroleum resin.

[0041] The surface layer 101 is a layer that is joined to the lid 3 by heat sealing or the like when the composite laminate 30 including the laminate 10 is molded into the container body 2 as shown in FIG. 1. The surface layer 101 is formed of, for example, a polyolefin resin. As a non-limiting example, if the surface layer 101 is torn when the container is opened, the thickness of the surface layer 101 is preferably 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less.

[0042] Fig. 4 is a schematic cross-sectional view showing a second configuration example of the resin substrate layer in the laminate shown in Fig. 2. In the illustrated example, the resin substrate layer 100 includes a first substrate layer 121 and second substrate layers 122 and 123 laminated on both sides of the first substrate layer 121. Although not shown, a surface layer 101 similar to that in the example of Fig. 3 may be laminated on the side of the second substrate layer 122 opposite the first substrate layer 121, i.e., on the side opposite the adhesive layer 200 in the resin substrate layer 100. The configuration of each layer will be described in more detail below.

[0043] The first base layer 121 is formed of a resin composition containing a polyolefin resin. From the viewpoints of heat resistance and hardness, the first base layer 121 preferably contains a polypropylene resin, and more preferably contains homopolypropylene. The melt flow rate of the polypropylene resin contained in the first base layer 121 is preferably 0.5 g / 10 min or more and 10 g / 10 min or less.

[0044] The second base layers 122, 123 are formed of a resin composition containing a polypropylene-based resin. The melt flow rate of the polypropylene-based resin contained in the second base layers 122, 123 is preferably 30.0 g / 10 min or less, more preferably 0.5 g / 10 min or more and 10.0 g / 10 min or less. The second base layers 122, 123 may also contain a nucleating agent. Examples of nucleating agents include sorbitol-based crystal nucleating agents. Commercially available products include Gelall MD (manufactured by New Japan Chemical Co., Ltd.) and Rikemaster FC-2 (manufactured by Riken Vitamin Co., Ltd.).

[0045] Note that the resin substrate layer 100 in the above example is not limited to a three-layer structure consisting of the first substrate layer 121 and the second substrate layers 122 and 123, but may be a multi-layer structure of four or more layers that includes, in addition to the first and second substrate layers, a barrier layer, an adhesive layer, or an anti-fogging layer containing an anti-fogging agent. Alternatively, as in the example shown in Fig. 5, the laminate may have the second substrate layer 122 on only one side of the first substrate layer 121.

[0046] FIG. 6 illustrates a manufacturing process for a laminate according to a second exemplary configuration. In the manufacturing process, a laminate 10 coextruded from a T-die 501 of an extruder is sandwiched between a first cooling roll 502 and a second cooling roll 503 together with a metallic endless belt 506. The metallic endless belt 506 is continuously transported by the cooling rolls and a transport roll 505. Each cooling roll is equipped with a cooling means (not shown), such as a water-cooled pipe. Immediately after molding, the laminate 10 is cooled by contact with the circumferential surfaces of the first cooling roll 502 and the second cooling roll 503 and the metallic endless belt 506. In a portion corresponding to approximately the lower half of the second cooling roll 503, while the laminate 10 is sandwiched between the metallic endless belt 506 and the second cooling roll 503, cooling water is sprayed onto the back side of the metallic endless belt 506 using a spray nozzle 507 to further cool the laminate 10. The sprayed cooling water is collected in a water tank 508. The laminate 10 leaves the second cooling roll 503 together with the metallic endless belt 506 and moves onto the third cooling roll 504, where it is cooled at a portion corresponding to approximately the upper half of the third cooling roll 504, and is then guided by the peeling roll 510 to separate from the third cooling roll 504 and the metallic endless belt 506, completing the cooling process, and is then transported further. Note that water adhering to the back surface of the metallic endless belt 506 is removed by a water absorbing roll 509 provided midway between the second cooling roll 503 and the third cooling roll 504.

[0047] According to the manufacturing process described above, the laminate 10 can be rapidly cooled to the required temperature immediately after molding by contact with multiple cooling rolls and a metal endless belt, and by spraying cooling water, thereby allowing the laminate 10 to exhibit, for example, mechanical properties and transparency.

[0048] (Configuration example for opening a container) An example of a configuration for opening the container 1 described with reference to FIG. 1 will be described below. The configuration described below is applicable to the configuration of the resin substrate layer 100 illustrated in FIGS. 3 to 5, for example, and is also applicable to other configurations of the resin substrate layer 100. Note that the container 1 does not necessarily have to have the configuration of the example described below; various configurations known as configurations for opening containers formed by laminates can be used. However, to prevent unintentional peeling of the resin substrate layer and the paper substrate layer when the container is opened, the following configuration is preferred, in which the peel strength between the resin substrate layer and the paper substrate layer can be adjusted to be higher than the peel strength between the container body and the lid. Note that the required openability can be ensured by adjusting the peel strength between the container body 2 and the lid 3, etc.

[0049] FIG. 7 is a schematic cross-sectional view showing a first example of a configuration for opening a container. In the illustrated example, the container body 2 is formed by molding a composite laminate 30 including a laminate 10 including a surface layer 101 and an undersurface layer 102 and a paper substrate layer 20 into a shape including a recess 2A and a flange portion 2B. Here, the surface layer 101 is a layer laminated on the side of the resin substrate layer 100 of the laminate 10 opposite the adhesive layer 200, as shown in FIG. 3, for example. The undersurface layer 102 corresponds to the layers of the resin substrate layer 100 of the laminate 10 other than the surface layer 101, and the adhesive layer 200. The surface layer 101 is located inside the container body 2, i.e., on the side facing the internal space SP, and faces the bonding region 4 formed in the flange portion 2B.

[0050] In the illustrated example, the surface layer 101 contains, for example, a polypropylene-based resin and at least one of an ethylene-acrylic ester-maleic anhydride copolymer or a styrene-grafted propylene resin. In this case, the ethylene-acrylic ester-maleic anhydride copolymer or the styrene-grafted propylene resin may be added in an amount of preferably 10 to 50 parts by mass, and particularly preferably 15 to 40 parts by mass, per 100 parts by mass of the polypropylene-based resin. Alternatively, the surface layer 101 contains a polypropylene-based resin, a polyethylene-based resin, and a styrene-ethylene-butene-styrene block copolymer. Alternatively, the surface layer 101 contains a polypropylene-based resin, a low-density polyethylene-based resin, and a metallocene-based polypropylene-based resin.

[0051] Meanwhile, in the illustrated example, the lid 3 is composed of a film-like laminate 300 including an outer layer 301 and a sealing layer 302. The outer layer 301 is located on the front side of the lid 3, i.e., the side facing away from the container body 2, and provides the flexibility and tensile strength required for the lid 3. The outer layer 301 is formed of, for example, a polyethylene terephthalate (PET) film or a biaxially oriented nylon film (O-Ny). On the other hand, the sealing layer 302 is located on the back side of the lid 3, i.e., the side facing the container body 2, and faces the joining region 4 formed in the flange portion 2B. The sealing layer 302 is formed of a resin composition such as random polypropylene, block polypropylene, linear low-density polyethylene, or polyethylene. Note that in other examples, the laminate 300 may also include additional layers.

[0052] In the above example, the cohesive strength of the surface layer 101 of the laminate 10 is weaker than the bond strength between the lid 3 and the container body 2 in the bonded region 4, weaker than the cohesive strength of each layer other than the surface layer 101 constituting the laminate 10 and the laminate 300, and weaker than the interlayer bond strength between each layer of the laminate 10 and the laminate 300. In other words, if the subsurface layer 102 is the first layer, the surface layer 101 is the second layer, the sealing layer 302 is the third layer, and the outer layer 301 is the fourth layer, the cohesive strength of the second layer is weaker than the bond strength between the lid 3 and the container body 2, the cohesive strength of the first layer, the third layer, and the fourth layer, and the interlayer bond strength between the first layer and the second layer and between the third layer and the fourth layer. As a result, as described below, the container 1 can be easily opened by using the surface layer 101 as a cohesive layer. In this specification, cohesive strength refers to the strength exerted by the intermolecular forces (cohesive forces) that bind the resins constituting each layer of the laminate.

[0053] Furthermore, in the above example, as shown in FIG. 7 , a first resin reservoir 51 and a second resin reservoir 52 are formed at the edge of the bonding region 4 on the recess 2A side. The first resin reservoir 51 has a nodule-shaped cross section and is made of the resin that forms the undersurface layer 102 and the surface layer 101 of the laminate 10. The second resin reservoir 52 is made of the resin that forms the sealing layer 302 of the lid 3 and has a nodule-shaped cross section that is located closer to the recess 2A than the first resin reservoir 51. As shown in the figure, the surface layer 101 is formed along the surface of the first resin reservoir 51 and passes through the gap between the first resin reservoir 51 and the second resin reservoir 52. In the following description, the first resin reservoir 51 and the second resin reservoir 52 are also collectively referred to as resin reservoir 50.

[0054] Next, the operation of opening the container 1 will be described. A user can begin opening the container 1 by grasping the end of the lid 3 extending beyond the flange portion 2B and peeling the lid 3 from this point, as shown in FIG. 2(A). As described above, the cohesive strength of the surface layer 101 is weaker than the bond strength between the lid 3 and the surface layer 101 in the bonding region 4, the cohesive strength of each layer other than the surface layer 101 of the laminate 10 and the laminate 300, and the interlayer bond strength between each layer of the laminate 10 and the laminate 300. Therefore, when a user peels off the lid 3, the surface layer 101, which is pulled by the lid 3 in the bonding region 4, undergoes cohesive failure. As a result, a portion of the surface layer 101 is peeled off together with the lid 3, and the remaining portion of the surface layer 101 remains on the subsurface layer 102 side. When the user further peels off the lid 3, the cohesive failure of the surface layer 101 stops at the resin reservoir portion 50, as shown in FIG. 2(B), and only the lid 3 is peeled off from that point onward. This is because, in the resin reservoir 50, the cohesive failure of the surface layer 101 progresses along the shape of the first resin reservoir 51. Near the edge 4E of the bonding area 4 where the surface of the first resin reservoir 51 and the surface of the second resin reservoir 52 move away from each other, the surface layer 101 is pulled from both sides, breaks, and moves away from the lid 3.

[0055] In the above example, weakening the cohesive strength of the surface layer 101 of the laminate 10 reduces the force required by the user to peel off the lid 3 during opening, making it easier to open. Meanwhile, before opening, when the container body 2 and the lid 3 are bonded together, the internal pressure of the internal space SP acts on the bonding region 4. Because the bonding strength between the lid 3 and the container body 2 in the bonding region 4 can be made stronger than the cohesive strength of the surface layer 101, even when weakening the cohesive strength of the surface layer 101 as described above facilitates opening, the bonding strength between the lid 3 and the container body 2 remains strong and can withstand high internal pressure. Additionally, stress is concentrated in the bonding region 4 near the base of the first resin reservoir 51 on the recess 2A side, allowing the bonding region 4 to withstand higher internal pressure than if no resin reservoir were formed. In this way, the above example achieves both easy opening and internal pressure resistance for the container 1.

[0056] FIG. 8 is a diagram illustrating a method for forming the resin reservoir portion of the container shown in FIG. 7. As shown in FIG. 8, the manufacturing process for the container 1 in this example includes a step of joining the lid 3 and the container body 2 by heat sealing using an annular sealing disk 601. Here, the annular sealing disk 601 includes a bulge 602 facing the inner periphery of the joining region 4 formed in the flange 2B of the container body 2, i.e., the edge portion on the recess 2A side, and an inclined surface 603 that widens outward from the bulge 602. Note that, in addition to the annular sealing disk 601 including the bulge 602 and the inclined surface 603, an additional annular sealing disk 605 including a flat surface 604 approximately parallel to the flange 2B may be disposed to join the outer periphery of the joining region 4.

[0057] In the above manufacturing process, when the annular sealing disk 601 descends from above in the figure, the bulge 602 comes into contact with the lid 3 before the other portions. Then, the inclined surfaces 603 sequentially come into contact with the lid 3. In the portions where the bulge 602 and the inclined surfaces 603 come into contact, heat is applied from the annular sealing disk 601 to the resin forming the lid 3 and the container body 2, and the lid 3 and the container body 2 are joined by heat sealing. At this time, at the edge portion on the inner periphery of the joining region 4, the resin forming the undersurface layer 102 and the surface layer 101 of the container body 2 and the seal layer 302 of the lid 3 is melted by the applied heat and pushed toward the recess 2A by the bulge 602 to form the first resin reservoir 51 and the second resin reservoir 52.

[0058] Fig. 9 is a schematic cross-sectional view showing a second configuration example for opening a container. In the example shown in Fig. 9, when the container is opened, the surface layer 101 breaks (edge ​​tear) and is peeled off from the other parts of the laminate 10.

[0059] As a first example of the above-described configuration, the surface layer 101 contains 50% by mass to 100% by mass of a polyethylene-based resin, preferably 95% by mass to 100% by mass. High-density polyethylene is preferred as the polyethylene-based resin. The thickness of the surface layer 101 is, for example, 5 μm to 40 μm, preferably 8 μm to 20 μm. The layer of the laminate 10 adjacent to the surface layer 101 contains, for example, a polypropylene-based resin. This polypropylene-based resin may be, for example, homopolypropylene, block polypropylene, or random polypropylene. This configuration is also described, for example, in JP 2004-167774 A and Japanese Patent No. 4159834 A.

[0060] As a second example of the above-described configuration, the surface layer 101 is formed from a resin composition containing homopolypropylene as the main component and having a tensile modulus of elasticity of 1500 MPa or more. The resin composition forming the surface layer 101 may contain, in addition to the main component homopolypropylene, a polypropylene-based resin such as random polypropylene or block polypropylene, a polyethylene-based resin such as high-density polyethylene or low-density polyethylene, or a linear ethylene-α-olefin copolymer. The thickness of the surface layer 101 is, for example, 5 μm or more and 40 μm or less, and preferably 10 μm or more and 30 μm or less. The density of high-density polyethylene is, for example, 920 kg / m 3 More than 990kg / m 3 The density of the high density polyethylene is preferably 935 kg / m 3 More preferably, 945 kg / m 3 The density of the high density polyethylene is preferably 966 kg / m 3 More preferably, 960 kg / m or less. 3The layer of the laminate 10 adjacent to the surface layer 101 is formed of a resin composition primarily composed of polyethylene. When the surface layer 101 is primarily composed of polypropylene, peeling between the surface layer 101 and the adjacent layer can be facilitated by using polyethylene as the primary component of the adjacent layer. More specifically, for example, the layer adjacent to the surface layer 101 is formed of a resin composition primarily composed of high-density polyethylene. In this case, the high-density polyethylene content is preferably greater than 55% by mass, more preferably 58% by mass or more, even more preferably 65% ​​by mass or more, and particularly preferably 70% by mass or more. The high-density polyethylene content may be 100% by mass. In this case, the layer adjacent to the surface layer 101 may further contain homopolypropylene. The homopolypropylene content is the remainder of the high-density polyethylene, i.e., preferably less than 45% by mass, more preferably 42% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. As described above, the content of high-density polyethylene may be 100% by mass, and therefore the content of homopolypropylene may be 0%. Such a configuration is also described, for example, in JP 2021-91219 A. [Example]

[0061] Next, examples of the present invention will be described. In the examples, a laminate including a resin substrate layer and an adhesive layer as described in the above embodiment was heated and then bonded to a paper substrate layer using compressed air to form a composite laminate. The composite laminate was then cut into a 30 mm x 30 mm rectangular sample piece, and the resin portion of the laminate and the paper substrate layer were peeled off. The feel and peeling morphology were evaluated. Table 1 shows six examples with different density and thickness of the paper substrate layer and compressed air pressure. In the evaluation, "A" indicates easy peeling, with clean interfacial peeling between the laminate and the paper substrate layer, and "B" indicates peeling, with general interfacial peeling between the laminate and the paper substrate layer. In each example, the resin substrate layer of the laminate had a thickness of 160 μm, the adhesive layer had a thickness of 40 μm, and the melt flow rate (MFR) of the adhesive layer was as shown in Table 1. Table 1 also shows the Martens hardness of the adhesive layer, measured according to JIS Z2255:2003 using a microhardness tester (product name: HM2000, manufactured by Fischerscope). As specific measurement conditions, the adhesive layer was used as the contact surface, and the measurement jig of the microhardness tester was used at a speed of 20 μm / 3 s with a maximum pressing amount of 20 μm.

[0062] In each example, the layer that adheres to the adhesive layer of the resin substrate layer is formed of block polypropylene, and has a melt flow rate of 0.4 g / 10 min and a density of 0.9 g / cm 3 The adhesive layers in Examples 1 to 6 were made of an acid-modified polyethylene resin (melt flow rate 8.5 g / 10 min). The adhesive layers in Examples 7 to 14 were made of an EVA-based resin 1 (melt flow rate 7.5 g / 10 min, containing 15% to 25% by mass of ethylene-1-hexene copolymer) and an EVA-based resin 2 (melt flow rate 2.5 g / 10 min, containing 60% to 70% by mass of ethylene-1-hexene copolymer) mixed together to adjust the melt flow rate to the value shown in Table 1. The paper base layer was made of a paper manufactured by Nippon Paper Industries Co., Ltd. under the trade name CUP-BL, and had a square meter weight, density, and thickness as shown in Table 1.

[0063] [Table 1]

[0064] In the above examples, it was shown that when the thickness of the resin substrate layer of the laminate adhered to the paper substrate layer is 70 μm or more, it is possible to easily separate the resin material and the paper material, for example, after use. [Explanation of symbols]

[0065] 1...container, 2...container body, 2A...recess, 2B...flange portion, 3...lid body, 4...joining region, 4E...edge, 10...laminate, 20...paper base layer, 30...composite laminate, 100...resin base layer, 101...surface layer, 102...subsurface layer, 111...oxygen barrier layer, 112...barrier adhesive layer, 113, 114, 121, 122, 123...base layer, 200...adhesive layer, SP...internal space.

Claims

1. A resin substrate layer containing at least a polyolefin resin and having a thickness of 70 μm or more, An adhesive layer capable of bonding the resin substrate layer to the paper substrate layer A laminate containing a

2. The laminate according to claim 1, wherein the thickness of the resin substrate layer is 1500 μm or less.

3. The laminate according to claim 1, wherein the thickness of the adhesive layer is 3 μm or more and 200 μm or less.

4. The laminate according to claim 1, wherein the melt flow rate of the adhesive layer is 80 g / 10 min or less.

5. The laminate according to claim 1, wherein the adhesive layer contains one or more components selected from the group consisting of acid-modified polyolefin resin, adhesives, and tackifying resins.

6. The laminate according to claim 1, wherein the adhesive layer contains acid-modified polyethylene.

7. The laminate according to claim 1, wherein the melt flow rate ratio of the adhesive layer is 80 or less when the melt flow rate of the resin substrate layer is 1.

8. The laminate according to claim 1, wherein the peel strength between the resin substrate layer and the adhesive layer is 1.0 kgf / 15 mm or more.

9. The laminate according to claim 1, wherein the resin substrate layer comprises a surface layer, a first substrate layer, and the adhesive layer in that order.

10. The aforementioned resin substrate layer is The surface layer and First substrate layer, An oxygen barrier layer and a pair of barrier adhesive layers laminated on both sides of the oxygen barrier layer, Second substrate layer and The laminate according to claim 1, comprising in this order.

11. The Martens hardness of the aforementioned adhesive layer at a temperature of 30°C is 0.1 N / mm². ２ 50N / mm or more ２ The laminate according to claim 1, which is as follows:

12. The Martens hardness of the adhesive layer at a temperature of 110°C is 0.01 N / mm². ２ 20N / mm or more ２ The laminate according to claim 1, which is as follows:

13. A container comprising a container body having a shape that includes the laminate according to claim 1 and the paper substrate layer bonded to the adhesive layer, and a recess and a flange portion formed along the periphery of the recess and extending outward from the periphery.

14. The container according to claim 13, wherein the container body is formed by bonding the laminate to the paper substrate layer, which is molded to include the recess and the flange portion, with the adhesive layer.

15. A container comprising a container body having a shape that includes a resin substrate layer containing at least a polyolefin resin and having a thickness of 70 μm or more, a paper substrate layer, and an adhesive layer for bonding the resin substrate layer to the paper substrate layer, and including a recess and a flange portion formed along the periphery of the recess and extending outward from the periphery.

16. The container according to any one of claims 13 to 15, further comprising a lid that is joined to the container body at a joining region formed on the flange portion, thereby forming an internal space between itself and the recess.

17. The container according to claim 16, wherein the peel strength between the adhesive layer and the paper substrate layer is higher than the peel strength between the container body and the lid.

18. The container according to any one of claims 13 to 15, wherein the peel strength between the adhesive layer and the paper substrate layer is 0.01 kgf / 15 mm or more and 10.0 kgf / 15 mm or less.

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