JP7666221B2 - Laminate and its manufacturing method, packaging body and packaged article - Google Patents

Description

The present invention relates to a laminate and its manufacturing method, a package, and a packaged article.

In laminates used as packaging materials, etc., a thermoplastic resin is used in the sealant layer. As this thermoplastic resin, polyethylene resin or polypropylene resin, etc., is particularly used because of its excellent lamination processability and heat sealability.

However, while these resins can achieve high adhesive strength due to their excellent heat sealing properties, they also tend to adsorb ingredients contained in medicines, foods, etc. Therefore, packaging that contains a sealant layer made of such a resin in contact with the space that contains the contents is prone to alteration or deterioration of the contents.

For this reason, polyester resins and polyacrylonitrile resins, which are low-adsorption materials, have been used in the sealant layers of laminates used in packaging pharmaceuticals, foods, etc. However, polyester resin films have problems with poor heat sealability, and polyacrylonitrile resin films have poor film-forming properties and also have problems from the standpoints of cost and stable procurement.

Patent Document 1 discloses a biaxially oriented film made of a cyclic olefin resin, with the objective of providing a packaging film that has low adsorption and excellent toughness and is suitable for packaging medicines, foods, etc. In this document, this cyclic olefin resin film is used as the sealant layer in a laminate consisting of polyethylene terephthalate/barrier layer (aluminum foil)/sealant layer, and the aluminum foil and the sealant layer are bonded together by a dry lamination method (paragraph 0043).

In this way, when bonding a low-adhesive sealant layer to a barrier layer such as aluminum foil, the dry lamination method is generally used. In this case, a two-part curing urethane adhesive is usually used as the adhesive for dry lamination.

However, when the contents to be packaged in the packaging material contain strongly penetrating substances such as fragrances for bath additives, poultice ingredients, alcohol, or various disinfectants, there is a problem that the strongly penetrating substances will penetrate into the laminate, which is the packaging material, during long-term storage. Since the barrier layer has gas barrier properties, the strongly penetrating substances that have penetrated into the laminate are trapped between the barrier layer and the sealant layer, dissolving the adhesive layer between the barrier layer and the sealant layer, causing a decrease in laminate strength. In particular, when a two-component curing urethane adhesive is used, the strongly penetrating substances significantly reduce the laminate strength between the barrier layer and the sealant layer, resulting in a problem of delamination (peeling). For this reason, when a low-adsorption sheet such as that in Patent Document 1 is used as the sealant layer of a packaging laminate, it is desirable to improve resistance to strongly penetrating substances in addition to adsorption resistance.

Patent Document 2 discloses a one-component curing adhesive containing an isocyanate compound as an adhesive that suppresses a decrease in laminate strength caused by highly penetrative substances being trapped between the barrier layer and the sealant layer in a laminate consisting of a barrier layer (aluminum foil, etc.), an adhesive layer, and a sealant layer.

International Publication No. 2017/033810 Patent No. 4306278

The adhesive containing an isocyanate compound disclosed in Patent Document 2 is an adhesive developed to prevent the laminate strength between the barrier layer and the sealant layer from decreasing due to the strong penetration force of the highly penetrating substance in a laminate consisting of a barrier layer/adhesive layer/sealant layer. As a result of extensive research by the inventors, it was found that in a laminate including an intermediate substrate layer between the barrier layer and the sealant layer, even if the above adhesive is used as the adhesive layer, there are cases where it is not possible to prevent the decrease in laminate strength due to the highly penetrating substance.

The present invention aims to provide a laminate used as a packaging material, which includes an intermediate substrate layer between a barrier layer and a sealant layer, has excellent resistance to adsorption of components contained in the contents, and suppresses the decrease in laminate strength caused by highly penetrating substances.

According to a first aspect of the present invention, a laminate is provided which comprises, in this order, a substrate layer, a barrier layer, an intermediate substrate layer, a first adhesive layer, an adhesive resin layer, and a sealant layer, the intermediate substrate layer containing a polyamide-based resin, the first adhesive layer containing an isocyanate compound having two or more isocyanate groups, the adhesive resin layer containing a low-density polyethylene resin or an ethylene-methacrylic acid copolymer, and the sealant layer containing a cyclic olefin-based resin.

According to a second aspect of the present invention, there is provided a method for producing a laminate according to the first aspect, comprising forming a first laminate having the base layer, the barrier layer, the intermediate base layer, and the first adhesive layer in this order, forming the adhesive resin layer by an extrusion lamination method, and laminating the first laminate and the sealant layer with the adhesive resin layer sandwiched therebetween so that the first adhesive layer and the sealant layer face each other.

According to a third aspect of the present invention, a package including the laminate according to the first aspect is provided.

According to a fourth aspect of the present invention, a packaged article is provided that includes a package according to the third aspect and contents packaged therein.

According to the present invention, a laminate is provided which is used as a packaging material and includes an intermediate substrate layer between a barrier layer and a sealant layer, and which has excellent resistance to adsorption of components contained in the contents and in which the decrease in laminate strength caused by highly penetrating substances is suppressed.

FIG. 2 is a partial cross-sectional view illustrating an example of a laminate according to an embodiment of the present invention. FIG. 13 is a partial cross-sectional view illustrating a laminate according to a modified example. FIG. 11 is a partial cross-sectional view illustrating a laminate according to another modified example.

The following describes an embodiment of the present invention with reference to the drawings. The embodiment described below is a more specific embodiment of one of the above aspects. Elements having the same or similar functions are given the same reference numerals, and duplicate descriptions are omitted.

FIG. 1 is a cross-sectional view that illustrates an example of a laminate according to an embodiment of the present invention.
1 includes, in this order, a substrate layer 11, a barrier layer 14, an intermediate substrate layer 17, a first adhesive layer 18, an adhesive resin layer 19, and a sealant layer 20. The first adhesive layer 18 and the adhesive resin layer 19 are interposed between the intermediate substrate layer 17 and the sealant layer 20, and bond the intermediate substrate layer 17 and the sealant layer 20 together. According to this embodiment, even in a configuration in which the intermediate substrate layer 17 is included between the barrier layer 14 and the sealant layer 20, a decrease in laminate strength caused by a highly penetrative substance between the barrier layer 14 and the sealant layer 20 can be suppressed.
Each layer contained in the laminate 1 will be described below.

(Base layer)
The base layer 11 is, for example, paper, a resin film, or a combination thereof. As the resin film, for example, a polypropylene film, a polyester film, a nylon film, or cellophane can be used.

The resin film can be a stretched film from the viewpoint of imparting mechanical strength to the laminate 1. The inclusion of a uniaxially or biaxially stretched polyethylene terephthalate film (PET) as the base layer 11 is advantageous in obtaining a laminate 1 with high stiffness.

The thickness of the substrate layer 11 is, in one example, in the range of 3 μm to 200 μm, and in another example, in the range of 6 μm to 30 μm.

A printed layer may be provided on the main surface of the base layer 11 depending on the application. The printed layer may be provided on the main surface of the base layer 11 that faces the barrier layer 14, or on the back surface, or on both of them.

(Barrier Layer)
The barrier layer 14 is a layer having a gas barrier property that reduces the permeability of gases such as water vapor and oxygen.

The barrier layer 14 may be, for example, a single layer made of an aluminum layer or an inorganic oxide layer, or may be a multilayer structure including an aluminum layer or an inorganic oxide layer. The barrier layer 14 is, for example, an aluminum foil, an aluminum vapor deposition film, or a transparent vapor deposition film. Note that a polyethylene terephthalate (PET) resin layer constitutes the barrier layer 14 in combination with an aluminum layer or an inorganic oxide layer, and layers consisting only of this resin layer are excluded from the barrier layer 14.

In one example, the thickness of the aluminum foil is in the range of 3 μm to 200 μm, and in another example, it is more preferable that the thickness is in the range of 5 μm to 100 μm. If the aluminum foil is too thin, it is difficult to handle when bonding it to a substrate. On the other hand, if the aluminum foil is thicker than a certain thickness, the barrier properties cannot be improved and the cost becomes high, and the flexibility as a packaging material tends to decrease, making it difficult to handle.

The aluminum vapor deposition film is a film in which an aluminum layer is vapor-deposited onto a first resin layer. The first resin layer is, for example, a biaxially oriented polyethylene terephthalate film, a biaxially oriented nylon film, or a biaxially oriented polypropylene film.

The thickness of the first resin layer is not particularly limited, but in one example, it is in the range of 3 μm to 200 μm, and in another example, it is in the range of 6 μm to 30 μm. In one example, the thickness of the aluminum vapor deposition layer is in the range of 5 nm to 100 nm. If the aluminum vapor deposition layer is too thin, it may not be possible to sufficiently prevent the intrusion of gases such as water vapor and oxygen. On the other hand, a thick aluminum vapor deposition layer not only increases costs, but also raises concerns that the vapor deposition layer may be more susceptible to cracking, leading to a decrease in barrier properties.

The transparent vapor deposition film is formed by forming an inorganic oxide layer on the second resin layer by means of a method such as vacuum deposition or sputtering. The second resin layer can be the same film as the first resin layer described above.

The inorganic oxide layer is made of inorganic oxides such as silicon oxide, aluminum oxide, magnesium oxide, etc. Most inorganic oxide thin film layers are colorless or very lightly colored transparent layers, and are suitable for use in packaging materials that require transparency. In addition, unlike metal layers, they are permeable to microwaves, so they can also be used as packaging materials for foods that are heated in a microwave oven.

In one example, the thickness of the inorganic oxide layer is in the range of 5 nm to 300 nm, and in another example, in the range of 10 nm to 150 nm. If the inorganic oxide layer is too thin, a uniform film may not be obtained or the thickness may be insufficient, and the inorganic oxide layer may not be able to fully function as a barrier layer 14. On the other hand, if the inorganic oxide layer is too thick, cracks may occur in the inorganic oxide layer when the laminate 1 is bent or pulled.

As transparent deposition films, for example, commercially available products such as "GL FILM" and "PRIME BARRIER (registered trademark)" (both manufactured by Toppan Printing Co., Ltd.) can be used.

When the barrier layer 14 is a single layer, for example, a vapor deposition layer, it can be laminated on one main surface of the substrate 11 as shown in FIG. 1. When the barrier layer 14 is, for example, an aluminum foil, an aluminum vapor deposition film, or a transparent vapor deposition film, it can be dry laminated on one main surface of the substrate layer 11 via an adhesive layer (not shown). As the adhesive layer, a two-component curing urethane adhesive that is commonly used as an adhesive for dry lamination can be used, and a known coating method such as a gravure coating method or a roll coating method can be used.

(Intermediate Base Material Layer)
The intermediate substrate layer 17 contains a polyamide resin. The intermediate substrate layer 17 improves the strength of the laminate 1. Furthermore, since the intermediate substrate layer 17 contains a polyamide resin, the adhesive strength with the adjacent first adhesive layer 18 is increased, which contributes to suppressing delamination (peeling) caused by a highly penetrative substance. That is, the amide bond contained in this polyamide resin reacts with the isocyanate bond of the isocyanate compound contained in the adjacent first adhesive layer 18 to form a strong urea bond at the interface. As a result, the decrease in laminate strength caused by the highly penetrative substance is suppressed, and the occurrence of lamination (peeling) is prevented.

The polyamide resin is, for example, a polyamide containing an aliphatic skeleton. For example, an aliphatic polyamide polymer or an aliphatic polyamide copolymer is used as the polyamide resin. Specific examples of the polyamide resin include aliphatic polyamide polymers such as nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, and nylon 46, and aliphatic polyamide copolymers such as nylon 6-66, nylon 6-610, nylon 66-610, and nylon 6-12. The aliphatic polyamides can be used alone or as a mixture of two or more kinds.

The intermediate substrate layer 17 may further include materials other than polyamide-based resin. For example, the intermediate substrate layer 17 may further include additives such as slip agents. The proportion of polyamide-based resin in the mass of the intermediate substrate layer 17 is preferably 99.0% by mass or more, and more preferably 99.9% by mass or more.

The thickness of the intermediate substrate layer 17 is preferably in the range of 3 μm to 200 μm, and more preferably in the range of 6 μm to 30 μm.

The intermediate substrate layer 17 may be dry laminated onto the principal surface of the barrier layer 14 opposite the substrate layer 11 side, for example, via an adhesive layer (not shown). As the adhesive layer, a two-component curing urethane adhesive that is commonly used as an adhesive for dry lamination can be used, and a known coating method such as a gravure coating method or a roll coating method can be used.

A printed layer may be provided on the main surface of the intermediate substrate layer 17 depending on the application. The printed layer may be provided on the main surface of the intermediate substrate layer 17 that faces the substrate layer 11, on the back surface, or on both surfaces.

(First adhesive layer)
The first adhesive layer 18 is a layer derived from a one-component curing adhesive containing an isocyanate compound having two or more isocyanate groups, and contains an isocyanate compound having two or more isocyanate groups.

Examples of isocyanate compounds having two or more isocyanate groups include diisocyanate monomers, or adduct type, biuret type, or trimer (isocyanurate) type derivatives of diisocyanate monomers. Specific examples of isocyanate compounds having two or more isocyanate groups include various diisocyanate monomers such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hydrogenated products thereof. In addition, trifunctional derivatives and polyfunctional derivatives having more than one functional group can be used, such as adduct types in which these diisocyanate monomers are reacted with trifunctional active hydrogen-containing compounds such as trimethylolpropane or glycerol, biuret types in which these diisocyanate monomers are reacted with water, and trimer (isocyanurate) types that utilize the self-polymerization of isocyanate groups.

The first adhesive layer 18 adheres the intermediate substrate layer 17 to the sealant layer 20 in a two-layer structure with the adjacent adhesive resin layer 19. The cooperation of these two layers improves the laminate strength between the barrier layer 14 and the sealant layer 20, and even if various highly permeable substances, including volatile substances such as alcohol, medicinal ingredients, and fragrance ingredients, act on the laminate 1, the laminate strength between the barrier layer 14 and the sealant layer 20 does not decrease, providing the desired adhesion and resistance to highly permeable contents.

In one example, the first adhesive layer 18 can be formed by applying a coating liquid containing the above-mentioned diisocyanate monomer or a derivative thereof in a solid content ratio of, for example, 1.0 to 10.0 mass % onto the main surface of the intermediate substrate layer 17 opposite the substrate layer 11. The mass per area (in a dry state) of the first adhesive layer 18 is preferably in the range of 0.05 to 0.25 g/ ^m2 , and more preferably in the range of 0.10 to 0.20 g/ ^m2 .

(Adhesive Resin Layer)
The adhesive resin layer 19 contains a low-density polyethylene resin (LDPE) or an ethylene-methacrylic acid copolymer (EMAA). The adhesive resin layer 19 exhibits good adhesive strength to the sealant layer 20, and therefore, in cooperation with the first adhesive layer 18 exhibiting good adhesive strength to the intermediate substrate layer 17 containing a polyamide resin, improves the lamination strength between the barrier layer 14 and the sealant layer 20, thereby providing the laminate 1 with desired adhesiveness and strong permeation content resistance.

The adhesive resin layer 19 is an extrusion resin layer formed by extrusion lamination. That is, the adhesive resin layer 19 is formed by extrusion lamination of a molten resin containing low-density polyethylene resin (LDPE) or ethylene-methacrylic acid copolymer (EMAA) on the main surface of the intermediate substrate layer 17 on which the first adhesive layer 18 is formed, or on one of the main surfaces of the sealant layer 20.

Low-density polyethylene resin (LDPE) is obtained by a known manufacturing method such as a high-pressure method. Low-density polyethylene resin is obtained, for example, by polymerizing ethylene obtained by pyrolysis of naphtha. According to one example, the melt flow rate (MFR) of the low-density polyethylene resin when the temperature is 190°C and the load is 21.168N (=2.16kgf) is preferably in the range of 3.6g/10min to 13.0g/10min, more preferably in the range of 4.0g/10min to 13.0g/10min, and even more preferably in the range of 5g/10min to 10.5g/10min. The melt flow rate (MFR) described here is a measured value obtained by a method conforming to JIS K7210:1999. Specifically, the melt flow rate (MFR) is the measured weight of resin extruded in 10 minutes when a load of 2.16 kgf is applied to the resin at 190°C. Hereinafter, the term "melt flow rate (MFR)" refers to the value obtained by this method.

When a low-density polyethylene resin (LDPE) with a melt flow rate (MFR) within the above range is used, physical properties suitable for extrusion lamination are obtained, and problems are unlikely to occur even when high-speed film production is performed. In this case, a homogeneous layer can be formed.

The density of the low-density polyethylene resin (LDPE) is preferably in the range of 0.915 g/cm ³ to 0.925 g/cm ³ , and more preferably in the range of 0.915 g/cm ³ to 0.922 g/cm ³ . If the density of the low-density polyethylene resin is too low, the film formation of the adhesive resin layer 19 is likely to be unstable. If the density of the low-density polyethylene resin is too high, the film formation is unstable. The density described here is a measured value obtained by a method in accordance with JIS K7112:1999.

Commercially available low-density polyethylene resins (LDPE) include, for example, "LC607K" (MFR at a temperature of 190°C and a load of 21.168N: 8.0 g/10 min, density: 0.919 g/cm ³ ) and "LC520" (MFR at a temperature of 190°C and a load of 21.168 N: 3.6 g/10 min, density: 0.923 g/cm ³ ). All of these resins are manufactured by Japan Polyethylene Corporation. In addition, LDPE "L417" manufactured by Sumitomo Chemical Co., Ltd. can also be suitably used as the adhesive resin layer 19.

The low-density polyethylene resin (LDPE) contained in the adhesive resin layer 19 has a different number of carbon atoms in the side chain branches relative to the main chain from linear low-density polyethylene resin. Low-density polyethylene resin has long-chain branches with more than about 20 carbon atoms. On the other hand, linear low-density polyethylene resin does not have long-chain branches with more than about 20 carbon atoms. Low-density polyethylene resin is superior to linear low-density polyethylene resin in that it is less likely to cause ear vibration or neck-in phenomena during extrusion film formation. Low-density polyethylene resin is also superior to linear low-density polyethylene resin in terms of tearability.

When laminating the adhesive resin layer 19 and the sealant layer 20 using the extrusion lamination method, a good film can be formed if the melting point of the low-density polyethylene resin is in the range of 100°C to 120°C. It is more preferable that the melting point of the low-density polyethylene resin (LDPE) is in the range of 100°C to 110°C. If the melting point is 120°C or higher, processing becomes difficult due to the ear-shaking phenomenon and the neck-in phenomenon.

The methacrylic acid content (hereinafter referred to as the acid content) of the ethylene-methacrylic acid copolymer (EMAA) is preferably in the range of 4% to 11% by mass. If the acid content is excessively small, the adhesive strength between the adhesive resin layer 19 and the first adhesive layer 18 tends to decrease, increasing the possibility of problems such as delamination occurring during long-term storage. Furthermore, if the acid content is excessively high, the adhesive strength between the adhesive resin layer 19 and the sealant layer 20 tends to decrease.

It is preferable that the ethylene-methacrylic acid copolymer (EMAA) has an MFR in the range of 7.0 g/10 min to 15.0 g/10 min.

When an ethylene-methacrylic acid copolymer (EMAA) having a melt flow rate within the above range is used, physical properties suitable for extrusion lamination are obtained, and problems are unlikely to occur even when high-speed film production is performed. In this case, a homogeneous layer can be formed.

The melting point of the ethylene-methacrylic acid copolymer (EMAA) is preferably in the range of 90°C to 110°C. Suitable cyclic olefin resins have a relatively low optimum extrusion temperature. When an ethylene-methacrylic acid copolymer with a low melting point is used, the difference between the melting point of the ethylene-methacrylic acid copolymer and the glass transition temperature of the cyclic olefin resin becomes small. In other words, their optimum extrusion temperatures can be brought closer together. Therefore, in this case, a high-quality layer can be formed at high speed.

Ethylene-methacrylic acid copolymer (EMAA) is, for example, a resin polymerized by a high-pressure method. An example of a commercially available product of ethylene-methacrylic acid copolymer is "Nucrel (registered trademark) N1108C" manufactured by DuPont-Mitsui Polychemicals Co., Ltd.

The thickness of the adhesive resin layer 19 is preferably 5 μm or more. The thickness of the adhesive resin layer 19 is preferably in the range of 5 μm to less than 30 μm, and more preferably in the range of 5 μm to 25 μm. If the thickness of the adhesive resin layer 19 is made excessively thin, the film formation of the adhesive resin layer 19 becomes unstable. If the thickness of the adhesive resin layer 19 is made excessively thick, adsorption is more likely to occur.

The adhesive resin layer 19 may further contain additives. The additives may be, for example, one or more of an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antiblocking agent, a flame retardant, a crosslinking agent, and a colorant.

(Sealant Layer)
The sealant layer 20 contains a cyclic olefin resin. The sealant layer 20 imparts heat sealability to the laminate 1 and also plays a role in enhancing the non-adsorption property of the laminate 1.

The sealant layer 20 may have a single layer structure or a multilayer structure. For example, the sealant layer 20 may have a single layer structure containing a cyclic olefin resin, or a multilayer structure including a layer containing a cyclic olefin resin and another resin layer. Examples of the other resin layer include polyolefin films such as polyethylene films and polypropylene films.

The cyclic olefin resin is preferably a ring-opening metathesis polymer (COP) obtained by polymerizing a cyclic olefin through a metathesis ring-opening polymerization reaction, a copolymer of a cyclic olefin and an α-olefin (a chain olefin), i.e., a cyclic olefin copolymer (COC), or a mixture thereof.

As the cyclic olefin, any cyclic hydrocarbon having an ethylenically unsaturated bond and a bicyclo ring can be used. In particular, the cyclic olefin is preferably one having a bicyclo[2.2.1]hept-2-ene (norbornene) skeleton.

As a cyclic olefin resin obtained from a cyclic olefin having a norbornene skeleton, for example, a ring-opening metathesis polymer of a norbornene monomer can be used. An example of a commercially available product of such a ring-opening metathesis polymer is "ZEONOR (Zeonor; registered trademark)" manufactured by Zeon Corporation. As a cyclic olefin resin obtained from a cyclic olefin having a norbornene skeleton, for example, a norbornene-based cyclic olefin copolymer can be used. As a commercially available product of such a cyclic olefin copolymer, for example, "Apel (registered trademark)" manufactured by Mitsui Chemicals, Inc. and "TOPAS (registered trademark)" manufactured by TOPAS ADVANCED POLYMERS GmbH and sold by Polyplastics Co., Ltd. can be used.

As the cyclic olefin resin, for example, a cyclic olefin copolymer, which is a copolymer obtained by copolymerizing ethylene and norbornene using a metallocene catalyst, can be suitably used. The cyclic polyolefin copolymer has the same non-adsorption property as the cyclic olefin polymer, and is inexpensively available. As the copolymer obtained by copolymerizing ethylene and norbornene using a metallocene catalyst, a copolymer containing a repeating unit represented by formula (a) and a repeating unit represented by formula (b) can be used. As a commercially available product of such a cyclic olefin resin, for example, "TOPAS (registered trademark)" manufactured by TOPAS ADVANCED POLYMERS GmbH and sold by Polyplastics Co., Ltd. can be mentioned.

Suitable cyclic olefin resins have a glass transition temperature in the range of, for example, 60°C to 100°C.

The sealant layer 20 may further include an additive. The additive may be, for example, one or more of a lubricant, an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antiblocking agent, a flame retardant, a crosslinking agent, and a colorant. As the lubricant, for example, a higher fatty acid metal salt, an aliphatic alcohol, a polyglycol, a triglyceride, a wax, a phenolic compound, or a mixture containing one or more of them may be suitably used for the purpose of improving processability. The wax may be a naturally derived wax, for example, a mineral wax such as montan wax, or a synthetic wax such as polyethylene wax.

From the viewpoint of physical strength, the sealant layer 20 is preferably a biaxially stretched film. Another advantage of biaxial stretching is that it is possible to produce a thin film. Cyclic olefin resins are prone to draw resonance, so it is difficult to directly produce a thin film, for example, one with a thickness of 30 μm or less, by extrusion.

The thickness of the sealant layer 20 is preferably 5 μm or more. The thickness of the sealant layer 20 is preferably in the range of 10 μm to 50 μm, and more preferably in the range of 10 μm to 30 μm. If the sealant layer 20 is made excessively thin, the film formation of the sealant layer 20 may become unstable, and the effect of suppressing adsorption may become small. On the other hand, if the sealant layer 20 is made excessively thick, the improvement in the effect of suppressing adsorption as the thickness of the sealant layer 20 increases is slight.

The sealant layer 20 is laminated so as to face the first adhesive layer 18, sandwiching between a first laminate having a base layer 11, a barrier layer 14, an intermediate base layer 17, and a first adhesive layer 18 in this order and an adhesive resin layer 19, which is an extruded resin layer formed by an extrusion lamination method.

For example, when the sealant layer 20 is a film, the laminate 1 can be formed by sandwiching the adhesive resin layer 19, which is an extruded resin layer, between the first laminate and the sealant layer 20 and bonding them together by a sandwich lamination method.
Alternatively, the laminate 1 can be formed by laminating the adhesive resin layer 19 and the sealant layer 20 on the first adhesive layer 18 of the first laminate by extrusion lamination or co-extrusion lamination.

<Modification>
Various modifications are possible for the laminate. As described above, the laminate according to the present embodiment may further include an adhesive layer not shown in FIG. 1, and may further include a printing layer not shown in FIG. 1. Modifications will be described below with reference to FIGS. 2 and 3. The matters described with reference to FIG. 1 can be applied to the laminate according to the modification described herein, either alone or in combination.

FIG. 2 is a partial cross-sectional view that shows a schematic diagram of a laminate according to a modified example.
2 includes, in this order, a substrate layer 11, a second adhesive layer 13, a barrier layer 14, a third adhesive layer 15, an intermediate substrate layer 17, a first adhesive layer 18, an adhesive resin layer 19, and a sealant layer 20. Except for including the second adhesive layer 13 between the substrate layer 11 and the barrier layer 14, and including the third adhesive layer 15 between the barrier layer 14 and the intermediate substrate layer 17, the laminate 2 is similar to the laminate 1 described with reference to FIG.

The second adhesive layer 13 and the third adhesive layer 15 can be formed, for example, by applying a two-component curing urethane adhesive that is commonly used as an adhesive for dry lamination. As the application method, a known method such as gravure coating or roll coating can be used.

The second adhesive layer 13 and the third adhesive layer 15 have a mass per area in a dry state in the range of 1.25 to 7.5 g/ ^m2 in one example, and in the range of 2.5 to 5.0 g/ ^m2 in another example.

FIG. 3 is a partial cross-sectional view that shows a schematic diagram of a laminate according to another modified example.
The laminate 3 shown in Fig. 3 comprises, in this order, a substrate layer 11, a printed layer 12, a second adhesive layer 13, a barrier layer 14, a third adhesive layer 15, a printed layer 16, an intermediate substrate layer 17, a first adhesive layer 18, an adhesive resin layer 19, and a sealant layer 20. Except for including the printed layer 12 between the substrate layer 11 and the second adhesive layer 13, and including the printed layer 16 between the third adhesive layer 15 and the intermediate substrate layer 17, the laminate 3 is similar to the laminate 2 described with reference to Fig. 2.

The printed layers 15 and 16 are layers formed so that the laminate 3, or a package or packaged article including the laminate 3, can be used as a commercial product. The printed layers 15 and 16 are layers formed of inks containing additives such as various pigments, extender pigments, plasticizers, desiccants, and stabilizers added to conventionally used ink binder resins such as urethane, acrylic, nitrocellulose, rubber, and vinyl chloride, and display patterns such as letters and designs. The printed layers 15 and 16 can be formed by known printing methods such as offset printing, gravure printing, and silk screen printing, or known coating methods such as roll coating, knife edge coating, and gravure coating.

The thickness of the printing layers 15 and 16 is not particularly limited, but in one example it is in the range of 0.1 to 5 μm, and in another example it is in the range of 0.2 to 1 μm.

Tests carried out in relation to the present invention are described below.
<1> Manufacturing of laminate (Example 1)
The laminate 2 shown in FIG. 2 was produced by the following method.
First, a biaxially oriented polyethylene terephthalate film (PET) having a thickness of 12 μm was prepared as the base layer 11. Furthermore, an aluminum foil having a thickness of 20 μm was prepared as the barrier layer 14.

Next, an ester-based urethane adhesive (aromatic two-component curing type) was applied to one main surface of the base layer 11 to form a second adhesive layer 13. The base layer 11 and the barrier layer 14 were laminated by a dry lamination method with the second adhesive layer 13 sandwiched therebetween to form a laminate a consisting of the base layer 11/second adhesive layer 13/barrier layer 14. The mass per area (coating amount) of the second adhesive layer 13 in a dry state was 3.0 g/ ^m2 .

Next, the same adhesive as that used for the second adhesive layer 13 was applied to the barrier layer 14 side of the laminate a to form a third adhesive layer 15. The laminate a and the intermediate base material layer 17 were laminated by a dry lamination method with the third adhesive layer 15 sandwiched therebetween to form a laminate b consisting of the base material layer 11/second adhesive layer 13/barrier layer 14/third adhesive layer 15/intermediate base material layer 17. The coating amount (dry state) of the third adhesive layer 15 was 3.0 g/ ^m2 . A biaxially oriented nylon film (ONY) having a thickness of 15 μm was used as the intermediate base material layer 17.

Next, a buret-type aliphatic one-component curing adhesive of diisocyanate monomer was applied to the intermediate substrate layer 17 side of the laminate b to form a first adhesive layer 18, thereby producing a first laminate consisting of substrate layer 11/second adhesive layer 13/barrier layer 14/third adhesive layer 15/intermediate substrate layer 17/first adhesive layer 18. Here, a buret-type hexamethylene diisocyanate (mixture mass ratio: hexamethylene diisocyanate/ethyl acetate = 5/95, solid content concentration: 4.98 mass%) was used as the buret-type aliphatic one-component curing adhesive of diisocyanate monomer. The coating amount (dry state) of the first adhesive layer 18 was 0.25 g/ ^m2 .

Next, an adhesive resin layer 19 was formed on the first adhesive layer 18 side of the first laminate by extrusion lamination, and the first adhesive layer 18 and the sealant layer 20 were attached so as to face each other with the adhesive resin layer 19 sandwiched therebetween, thereby producing the laminate 2 shown in Fig. 2. Here, a low-density polyethylene resin (LDPE) (L417, manufactured by Sumitomo Chemical Co., Ltd.; MFR 5 g/10 min, density 0.922 g/cm ³ ) was used as the adhesive resin layer 19. The thickness of the adhesive resin layer 19 (thickness after lamination) was 13 µm. A biaxially stretched film of cyclic olefin copolymer (COC) (TSC-1, manufactured by Kurabo Industries Co., Ltd.; thickness 25 µm) was used as the sealant layer 20.

(Example 2)
A laminate 2 was produced in the same manner as in Example 1, except that the coating amount (in a dry state) of the first adhesive layer 18 was changed from 0.25 g/m ² to 0.15 g/m ² .

(Example 3)
A laminate 2 was produced in the same manner as in Example 1, except that the coating amount (in a dry state) of the first adhesive layer 18 was changed from 0.25 g/m ² to 0.05 g/m ² .

(Example 4)
Laminate 2 was produced in the same manner as in Example 1, except that the sealant layer 20 was changed from a biaxially stretched film of cyclic olefin copolymer (COC) to an unstretched film of cyclic olefin copolymer (COC) (ME-1, manufactured by Kuraray Industries, Inc.; thickness 25 μm).

(Example 5)
A laminate 2 was produced in the same manner as in Example 1, except that the adhesive resin layer 19 was changed from low-density polyethylene resin (LDPE) to ethylene-methacrylic acid copolymer (EMAA) (N1108C, manufactured by Dow Mitsui Polychemical Co., Ltd.).

(Example 6)
A laminate 2 was produced in the same manner as in Example 1, except that the barrier layer 14 was changed from aluminum foil to an alumina-deposited PET film (GL-ARH, manufactured by Toppan Printing Co., Ltd.; thickness: 20 μm).

(Example 7)
Laminate 2 was produced in the same manner as in Example 1, except that the sealant layer 20 was changed from a biaxially stretched film of cyclic olefin copolymer (COC) to a coextruded two-layer film of cyclic olefin copolymer (COC)/polyethylene (MP series M3400MP, manufactured by DIC Corporation; thickness 30 μm).

(Comparative Example 1)
A laminate was produced in the same manner as in Example 1, with the following exceptions.
That is, the adhesive A was applied to the intermediate substrate layer 17 side of the laminate b consisting of the substrate layer 11/second adhesive layer 13/barrier layer 14/third adhesive layer 15/intermediate substrate layer 17 obtained in Example 1 to form an adhesive layer. The sealant layer 15 was laminated on this adhesive layer by a dry lamination method to obtain a laminate consisting of the substrate layer 11/second adhesive layer 13/barrier layer 14/third adhesive layer 15/intermediate substrate layer 17/adhesive layer/sealant layer 20. Here, the adhesive A was an ester-based urethane adhesive (aromatic two-component curing type) that was the same as the adhesive used in the second adhesive layer 13 and the third adhesive layer 15. As the sealant layer 20, the same biaxially stretched COC film as the film used in Example 1 was used.

(Comparative Example 2)
A laminate was produced in the same manner as in Comparative Example 1, except that adhesive A was changed from an ester-based urethane adhesive (aromatic two-component curing type) to an ester-based urethane adhesive (aliphatic two-component curing type).

(Comparative Example 3)
A laminate was produced in the same manner as in Example 1, except that the sealant layer 20 was changed from a biaxially oriented film of cyclic olefin copolymer (COC) to a linear low density polyethylene film (LLDPE) (MZ434, manufactured by Tamapoly Co., Ltd.; thickness 25 μm).

(Comparative Example 4)
A laminate was produced in the same manner as in Example 1, except that the sealant layer 20 was changed from a biaxially stretched film of cyclic olefin copolymer (COC) to an ethylene-methacrylic acid ionomer film (EMAA) (N1108C manufactured by Mitsui-Dow Polychemical Co., Ltd.; thickness 25 μm).

(Comparative Example 5)
A laminate was produced in the same manner as in Example 1, except that the sealant layer 20 was changed from a biaxially oriented film of cyclic olefin copolymer (COC) to unoriented polypropylene (CPP) (RS-503C, manufactured by Idemitsu Unitech Co., Ltd.; thickness 25 μm).

(Comparative Example 6)
A laminate was produced in the same manner as in Example 1, except that the intermediate substrate layer 17 was changed from the biaxially oriented nylon film (ONY) to a polyethylene terephthalate (PET) film having a thickness of 12 μm.

(Comparative Example 7)
A laminate was produced in the same manner as in Example 1, except that the barrier layer 14 was changed from aluminum foil to polyethylene terephthalate (PET).

<2> Evaluation Evaluation samples were prepared using each of the laminates of Examples 1 to 7 and Comparative Examples 1 to 7. First, two test pieces measuring 10 cm x 10 cm were cut out from each laminate, and the two test pieces were stacked so that the sealant layer was on the inside, and three sides were heat-sealed to form a bag shape. Next, menthol was placed in the bag, and the remaining side was heat-sealed to prepare a menthol-containing packaging bag as an evaluation sample. These samples were stored for one month in a thermostatic chamber at a temperature of 40°C and a relative humidity of 75%, and then the adsorption resistance, lamination strength, and water vapor barrier property were evaluated by the methods described below.

(Menthol adsorption resistance)
After the drug component menthol was removed from each sample, the packaging bag was cut into small pieces. The cut test pieces were immersed in methanol to obtain a menthol extract. The menthol extract was then analyzed by high performance liquid chromatography to quantify the amount of menthol adsorbed to the packaging bag. Based on this, the amount of menthol adsorbed per area of the packaging bag was calculated. The pass standard was a menthol adsorption amount of 3.0 μg/ ^cm2 or less, and 3.0 μg/ ^cm2 or less was evaluated as A, and more than 3.0 μg/ ^cm2 was evaluated as B. The results are summarized in Table 1.

(Laminate strength)
After removing the medicinal ingredient menthol from each sample, the packaging bag was cut into a 15 mm wide strip, and the barrier layer and the sealant layer were peeled off at a tensile speed of 300 mm/min using an RTF-1250 manufactured by A&D Co., Ltd., to measure the laminate strength. A laminate strength of 15.0 N/15 mm or more was set as the pass criterion, with 15.0 N/15 mm or more being rated as A and less than 15.0 N/15 mm being rated as B. The results are summarized in Table 1.

(Water vapor permeability)
After removing the pharmaceutical ingredient menthol from each sample, the packaging bag was cut into an octagonal shape using a special tool, and a water vapor transmission rate measuring device (MOCON, Hitachi High-Tech Science Corporation) was used to perform 3 cycles of 20-minute measurements under an atmosphere of temperature (40)°C and relative humidity (90), and the average value was taken as the water vapor transmission rate. A water vapor transmission rate of 1.0 g/ ^m2 /day or less was set as the pass criterion, with 1.0 g/ ^m2 /day or less being rated as A and over 1.0 g/ ^m2 /day being rated as B. The results are summarized in Table 1.

From the results shown in Table 1, it was found that the laminate according to this embodiment, as a packaging laminate, is excellent in all respects, including adsorption resistance to components contained in the contents, peel resistance to highly permeable substances, and water vapor barrier properties.

The present invention is not limited to the above-described embodiment, and various modifications can be made in the implementation stage without departing from the gist of the invention. The embodiments may be implemented in appropriate combination, in which case the combined effects can be obtained. Furthermore, the above-described embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple constituent elements disclosed. For example, if the problem can be solved and an effect can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the configuration from which the constituent elements are deleted can be extracted as an invention.

1, 2, 3... laminate, 11... substrate layer, 12... printing layer, 13... second adhesive layer, 14... barrier layer, 15... third adhesive layer, 16... printing layer, 17... intermediate substrate layer, 18... first adhesive layer, 19... adhesive resin layer, 20... sealant layer.

Claims (7)

A laminate comprising a substrate layer, a barrier layer, an intermediate substrate layer, a first adhesive layer, an adhesive resin layer, and a sealant layer in this order, the intermediate substrate layer containing a polyamide resin, the first adhesive layer containing an isocyanate compound having two or more isocyanate groups, the adhesive resin layer containing a low-density polyethylene resin or an ethylene-methacrylic acid copolymer, and the sealant layer containing a cyclic olefin resin. The laminate of claim 1 , wherein the first adhesive layer has a mass per area in the range of 0.05 to 0.25 g/m ² . The laminate according to claim 1 or 2, wherein the sealant layer is a biaxially stretched film. The laminate according to any one of claims 1 to 3, wherein the barrier layer comprises an aluminum foil or an inorganic oxide layer. forming a first laminate comprising, in order, the substrate layer, the barrier layer, the intermediate substrate layer, and the first adhesive layer; and
The adhesive resin layer is extruded, and the first laminate and the sealant layer are laminated together so that the first adhesive layer and the sealant layer face each other with the adhesive resin layer sandwiched therebetween; or
The method for producing a laminate according to claim 1 , further comprising laminating the adhesive resin layer and the sealant layer on the first adhesive layer side of the first laminate by extrusion molding or co-extrusion molding. A package including the laminate according to any one of claims 1 to 4. A packaged article comprising the package according to claim 6 and contents packaged therein.