Stacked polyolefin-based stretchable resin films, packaging materials, packaging bags, and packaging objects.

Abstract

Invention details;

Description

Stretched laminated polyolefin resin film, packaging material, packaging bag, and package

[0001] The present invention relates to an environmentally friendly stretched laminated polyolefin resin film, a packaging material, a packaging bag, and a package, which are used in the packaging fields of foods, medicines, industrial products, etc.

[0002] In recent years, regulations aimed at reducing the use of disposable plastics have been strengthened in Europe and other countries around the world. Behind these trends are growing international awareness of resource recycling and the worsening waste problems in emerging countries. Therefore, environmentally friendly products are being sought from the perspective of the 3Rs (Recycle, Reuse, Reduce) for plastic packaging materials required for food, pharmaceuticals, etc.

[0003] One possibility for making packaging materials more environmentally friendly is to make them from the same recyclable material, i.e., to make them mono-material. For example, polyester-based or polyolefin-based materials are being developed as mono-materials.

[0004] While there is a demand for packaging materials with a low environmental impact, as mentioned above, the current situation is that the properties required of packaging materials themselves are becoming increasingly multifunctional for convenience. For example, retort pouches that can be used in microwave ovens are required to simultaneously provide gas barrier properties, heat resistance, water resistance, toughness (bag tear resistance and pinhole resistance), and high sealability, all without using aluminum foil. To achieve these, different materials with different functions must be bonded together. A typical structure is one with at least three layers: a vapor-deposited polyester film on the outside, a polyamide film in the middle, and a polyolefin sealant on the inside (content side) dry-laminated with an adhesive. While this structure can achieve the desired performance, bonding different materials together makes it less recyclable, which makes it less than environmentally friendly.

[0005] Considering these points, studies are underway to design bags with the aforementioned multifunctionality even using the same material that can be made into a monomaterial. However, even if the constituent material is made into a monomaterial, there are challenges in peeling off each layer and recycling it. To address this issue, one possible solution is to make the sealant, which accounts for the largest proportion of the packaging material in terms of thickness, multifunctional and minimize the number of constituent layers. This would provide the ideal packaging material that is most easily recyclable, and various studies are being conducted in this area.

[0006] For example, Patent Document 1 discloses a polyester-based sealant with improved low adsorption and heat resistance as an alternative to conventional polyolefin-based sealants. The polyester-based sealant in Patent Document 1 has a separate layer with heat-sealability and other layers, and the raw material compositions of these layers are controlled separately to achieve both heat-sealability and heat resistance. However, there is a problem in that the heat-sealability is somewhat inferior to the seal strength of unstretched polyolefin-based sealants. Also disclosed (see, for example, Patent Document 2) is a barrier sealant having a gas barrier layer on the opposite side of the polyester-based sealant's seal layer. While the polyester-based sealant in Patent Document 2 has a barrier layer, the improvement in barrier property is not sufficient, and there is no mention of improving water vapor barrier property in particular.

[0007] On the other hand, polyolefin-based sealants often use unstretched polypropylene-based resin films or stretched polypropylene-based resin films. These resins are known to have sufficient seal strength. However, when viewed as a mono-material packaging material, polypropylene-based resin films lack the necessary stiffness and toughness. For example, a polypropylene-based resin film has been disclosed in which a polypropylene-based resin is laminated with a low-melting-point polyolefin-based resin, co-extruded, and then stretched (see, for example, Patent Document 3). This stretched polypropylene-based resin film has a certain degree of seal strength, but the stiffness and heat resistance of the film are insufficient.

[0008] Furthermore, the gas barrier properties of the polypropylene-based resin film in Patent Document 3 are not investigated, and there is a problem that the polyolefin-based sealant has significantly inferior gas barrier properties compared to conventional materials having barrier properties. For example, although a polyolefin-based resin film has a certain degree of water vapor barrier property due to its structure, the water vapor barrier property of the polyolefin-based resin film is not sufficient compared to inorganic vapor-deposited polyester-based resin films, which are generally considered to have excellent water vapor barrier properties, and there is also a problem that the oxygen barrier property of the polyolefin-based resin film is very poor.

[0009] Patent Document 4 describes vapor-depositing a barrier material onto a polyolefin-based sealant. While this sealant exhibits water vapor barrier properties, it suffers from the problem of insufficient oxygen barrier properties. Furthermore, because it is a non-oriented polyolefin-based sealant, it is inferior in stiffness and toughness as a film, leaving room for improvement as a desired mono-material packaging material.

[0010] Japanese Patent Application Laid-Open No. 2017-165059 Japanese Patent Application Laid-Open No. 2017-165060 Japanese Patent No. 4120227 Japanese Patent No. 3318479

[0011] For the reasons described above, in Patent Documents 1 to 4, it was difficult to achieve both mono-material packaging materials and the various performance properties required of packaging materials (gas barrier properties, heat seal properties, heat resistance, toughness, and firmness), and it was not possible to design environmentally friendly and convenient packaging materials.

[0012] The present invention has been made in view of the problems of the prior art. That is, an object of the present invention is to provide a stretched laminated polyolefin resin film, a packaging material, a packaging bag, and a package, which are made of a resin that has a low environmental impact and have gas barrier properties, heat sealability, heat resistance, stiffness, and toughness.

[0013] The present inventors have discovered that by laminating a predetermined gas barrier layer onto a stretched polyolefin film having a low-melting point resin layer (e.g., an intermediate layer or a heat-sealable layer) to form a laminate film, it is possible to significantly improve gas barrier properties and ensure high heat sealability, heat resistance, stiffness and toughness, thereby providing an environmentally friendly and highly convenient packaging material, which has led to the completion of the present invention.

[0014] That is, the present invention has the following configuration. 1. A stretched laminated polyolefin resin film comprising a base layer, an intermediate layer, and a heat-sealable layer containing a polyolefin resin having a melting point of 150°C or less laminated in that order, the stretched laminated polyolefin resin film having a gas barrier layer on the surface opposite to the surface of the heat-sealable layer, and satisfying the following requirements (a) to (d): (a) the puncture strength of the film is 10 N or more. (b) the Young's moduli of the film in the MD and TD directions are each 1 GPa or more. (c) the seal strength when the heat-sealable layers of the film are heat-sealed together at 150°C, 0.2 MPa, for 2 seconds is 8 N / 15 mm or more. (d) the shrinkage rate of the film after heating at 120°C for 15 minutes is 10% or less in both the MD and TD directions. 2. The base layer, intermediate layer, and heat-sealable layer are each composed of a polyolefin resin composition containing a propylene homopolymer or a propylene copolymer as a constituent component. 3. The stretched laminated polyolefin resin film according to 1. or 2., wherein the content of the propylene copolymer constituting the intermediate layer is more than 60% by mass in the polyolefin resin composition constituting the intermediate layer. 4. The stretched laminated polyolefin resin film according to any one of 1. to 3., wherein the relationship of thickness of the base layer > thickness of the intermediate layer > thickness of the heat-sealable layer is satisfied. 5. The stretched laminated polyolefin resin film according to any one of 1. to 4., wherein the gas barrier layer is an inorganic thin film layer made of any one of aluminum, aluminum oxide, silicon oxide, and a composite oxide of silicon oxide and aluminum oxide. 6. The stretched laminated polyolefin resin film according to any one of 1. to 5., wherein the gas barrier layer is a coating layer containing one or more of polyvinyl alcohol resin, polyester resin, polyurethane resin, and inorganic layered compound. 7. The stretched laminated polyolefin resin film according to any one of 1. to 6., wherein an anchor coat layer is laminated between the film and the gas barrier layer. 8. The stretched laminated polyolefin resin film according to 1., wherein a protective layer is laminated on the gas barrier layer. 9. The stretched laminated polyolefin resin film according to any one of items 1 to 7., wherein the oxygen permeability under conditions of 23°C and 65% RH is 800 ml / m 210. The stretched laminated polyolefin resin film according to any one of 1. to 8., wherein the water vapor permeability under conditions of 40°C and 90% RH is 3.0 g / m or less. 2 - A stretched laminated polyolefin resin film according to any one of 1. to 9., wherein d is not more than 1. 11. A stretched laminated polyolefin resin film according to any one of 1. to 10., which is used for heating in a microwave oven. 12. A packaging material obtained by laminating the film according to any one of 1. to 11. 13. The packaging material according to 12., in which a barrier adhesive layer is laminated on the gas barrier layer. 14. A packaging bag made from the packaging material according to 12. 15. A package in which an item to be packaged is packaged in the packaging material according to 12. 16. A package in which an item to be packaged is packaged in the packaging bag according to 14.

[0015] The present invention makes it possible to provide a stretched laminated polyolefin resin film that is made of a resin that has a low environmental impact and that has gas barrier properties, heat sealability, heat resistance, stiffness, and toughness.

[0016] The stretched laminated polyolefin resin film of the present invention is a stretched laminated polyolefin resin film formed by sequentially laminating a base layer, an intermediate layer, and a heat-sealable layer containing a polyolefin resin having a melting point of 150°C or less, and has a gas barrier layer on the surface opposite to the heat-sealable layer, and is characterized by satisfying the following requirements (a) to (d): (a) the puncture strength of the film is 10 N or more (preferably 12 N or more), (b) the Young's moduli of the film in the MD and TD directions are each 1 GPa or more, (c) the seal strength when the heat-sealable layers of the film are heat-sealed together at 150°C, 0.2 MPa, for 2 seconds is 8 N / 15 mm or more, and (d) the shrinkage of the film after heating at 120°C for 15 minutes is 10% or less in both the MD and TD directions.

[0017] The present invention will be described in detail below. [Stretched laminated polyolefin resin film] The stretched laminated polyolefin resin film of the present invention is formed by laminating in order a substrate layer, an intermediate layer, and a heat-sealing layer containing a polyolefin resin having a melting point of 150°C or less. The stretched laminated polyolefin resin film may be a uniaxially stretched film or a biaxially stretched film, and is preferably a biaxially stretched film. The substrate layer, intermediate layer, and heat-sealing layer are each preferably composed of a polyolefin resin composition containing a propylene homopolymer or a propylene copolymer as a constituent component.

[0018] Substrate Layer The substrate layer is a layer for bonding another substrate film capable of constituting a monomaterial, such as a stretched polyolefin resin film, and the substrate film is preferably laminated via an adhesive resin. A printed layer may be provided on the substrate layer. The substrate layer may be a single layer or two or more layers, and is preferably a single layer.

[0019] The substrate layer is preferably made of a polyolefin resin composition containing a propylene homopolymer or a propylene copolymer as a constituent component. The propylene homopolymer and the propylene copolymer may have a predetermined melt flow rate (MFR) and melting point.

[0020] The melt flow rate (MFR) (230°C, 2.16 kg load) of the propylene homopolymer is preferably 1.8 g / 10 min or more, more preferably 2.0 g / 10 min or more, even more preferably 2.2 g / 10 min or more, and preferably 10.0 g / 10 min or less, more preferably 8.0 g / 10 min or less, and even more preferably 6.0 g / 10 min or less. When the melt flow rate of the propylene homopolymer is within the above range, workability and film strength are improved. The melt flow rate is measured, for example, based on JIS K-7210-1 (measurement conditions: 230°C, 2.16 kg load).

[0021] The melting point of the propylene homopolymer is preferably 150°C or higher, more preferably 152°C or higher, even more preferably 154°C or higher, still more preferably 156°C or higher, and preferably 170°C or lower, more preferably 167°C or lower, and even more preferably 164°C or lower. When the melting point of the propylene homopolymer is within the above range, heat resistance can be improved. The melting point can be measured using, for example, a differential scanning calorimeter.

[0022] Examples of commercially available propylene homopolymers include FLX80E4 (MFR 7.5 g / 10 min, melting point 164°C) manufactured by Sumitomo Chemical Co., Ltd., F-300SP (MFR 3.0 g / 10 min, melting point 160°C) manufactured by Prime Polymer Co., Ltd., and FS2011DG3 (MFR: 2.5 g / 10 min, melting point 158°C) manufactured by Sumitomo Chemical Co., Ltd.

[0023] The propylene copolymer is preferably a propylene-α-olefin copolymer (containing no α-olefins having 3 carbon atoms), and may be either a block copolymer or a random copolymer. The α-olefin monomer constituting the propylene-α-olefin copolymer is preferably an α-olefin monomer having 2 or 4 to 10 carbon atoms, and more preferably ethylene, butene, pentene, hexene, octene, decene, or the like, as the α-olefin monomer having 2 or 4 to 10 carbon atoms. The propylene copolymer (preferably a propylene-α-olefin copolymer) is preferably a propylene-ethylene copolymer, a propylene-butene copolymer, a propylene-pentene copolymer, a propylene-methylpentene copolymer, a propylene-hexene copolymer, a propylene-octene copolymer, a propylene-ethylene-butene copolymer, or the like.

[0024] The melt flow rate (MFR) of the propylene copolymer (230°C, load 2.16 kg) is preferably 2.0 g / 10 min or more, more preferably 2.2 g / 10 min or more, even more preferably 2.4 g / 10 min or more, and preferably 8.0 g / 10 min or less, more preferably 7.5 g / 10 min or less, and even more preferably 7.0 g / 10 min or less. When the melt flow rate of the propylene copolymer is within the above range, workability and film strength are improved.

[0025] The melting point of the propylene copolymer is preferably 140° C. or higher, more preferably 142° C. or higher, even more preferably 144° C. or higher, still more preferably 146° C. or higher, and is preferably 165° C. or lower, more preferably 160° C. or lower, and even more preferably 155° C. or lower. When the melting point of the propylene copolymer is within the above range, heat resistance can be improved.

[0026] The propylene copolymer (preferably a propylene-α-olefin copolymer) preferably contains at least one selected from a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of 1.0 mol% or less and a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol%, and more preferably contains a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of 1.0 mol% or less.

[0027] The copolymerization ratio of the α-olefin in a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having an olefin copolymerization ratio of 1.0 mol% or less is preferably 0.9 mol% or less, more preferably 0.8 mol% or less, even more preferably 0.7 mol% or less, and is preferably 0.1 mol% or more, more preferably 0.15 mol% or more, and even more preferably 0.2 mol% or more. By setting the copolymerization ratio within the above range, heat resistance and firmness can be improved.

[0028] The resin composition containing the polyolefin resin that constitutes the base layer is preferably composed of a propylene homopolymer or a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) in which the copolymerization ratio of the α-olefin is 1.0 mol% or less, and more preferably composed of a propylene homopolymer. One or more types of propylene homopolymers or propylene copolymers may be used. Furthermore, the propylene homopolymer is preferably an isotactic crystalline polypropylene resin that is insoluble in n-heptane.

[0029] The polyolefin-based resin-containing resin composition constituting the substrate layer contains 60% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, still more preferably 95% by weight or more, and particularly preferably 100% by weight of at least one polymer selected from propylene homopolymers and propylene copolymers (preferably propylene-α-olefin copolymers (α-olefins having 2 or 4 to 10 carbon atoms)). The polyolefin-based resin-containing resin composition constituting the substrate layer most preferably contains 100% by weight of propylene homopolymer.

[0030] The stretched laminated polyolefin resin film of the present invention has an intermediate layer between the above-mentioned base layer and the heat-sealing layer. This intermediate layer is provided to improve the interlayer strength between the base layer and the heat-sealing layer and to provide the stretched laminated polyolefin resin film of the present invention with appropriate stiffness and heat-sealing strength.

[0031] The intermediate layer is preferably composed of a polyolefin resin composition containing a propylene homopolymer or a propylene copolymer as a constituent component. One or more types of propylene homopolymers or propylene copolymers may be used. Furthermore, the polyolefin resin composition constituting the intermediate layer may contain an olefin copolymer other than propylene homopolymers and propylene copolymers (sometimes referred to as olefin copolymer X). The intermediate layer may be a single layer or two or more layers, and is preferably a single layer.

[0032] The propylene homopolymer and the propylene copolymer may be any propylene homopolymer and propylene copolymer as long as they have a predetermined melt flow rate (MFR) and melting point.

[0033] The melt flow rate (MFR) (230°C, 2.16 kg load) of the propylene homopolymer is preferably 1.8 g / 10 min or more, more preferably 2.0 g / 10 min or more, even more preferably 2.2 g / 10 min or more, and preferably 10.0 g / 10 min or less, more preferably 8.0 g / 10 min or less, and even more preferably 6.0 g / 10 min or less. When the melt flow rate of the propylene homopolymer is within the above range, workability and film strength are improved. The melt flow rate is measured, for example, based on JIS K-7210-1 (measurement conditions: 230°C, 2.16 kg load).

[0034] The melting point of the propylene homopolymer is preferably 150°C or higher, more preferably 152°C or higher, even more preferably 154°C or higher, still more preferably 156°C or higher, and preferably 170°C or lower, more preferably 167°C or lower, and even more preferably 164°C or lower. When the melting point of the propylene homopolymer is within the above range, the firmness can be improved. The melting point can be measured, for example, using a differential scanning calorimeter.

[0035] Examples of commercially available propylene homopolymers include FLX80E4 (MFR 7.5 g / 10 min, melting point 164°C) manufactured by Sumitomo Chemical Co., Ltd., F-300SP (MFR 3.0 g / 10 min, melting point 160°C) manufactured by Prime Polymer Co., Ltd., and FS2011DG3 (MFR: 2.5 g / 10 min, melting point 158°C) manufactured by Sumitomo Chemical Co., Ltd.

[0036] The propylene copolymer is preferably a propylene-α-olefin copolymer (not including an α-olefin having 3 carbon atoms), and may be either a block copolymer or a random copolymer, with a random copolymer being preferred. The α-olefin is preferably an α-olefin monomer having 2 or 4 to 10 carbon atoms, and more preferably ethylene, butene, pentene, hexene, octene, decene, or the like, as the α-olefin monomer having 2 or 4 to 10 carbon atoms. The propylene copolymer (preferably a propylene-α-olefin copolymer) is preferably a propylene-ethylene copolymer, a propylene-butene copolymer, a propylene-pentene copolymer, a propylene-methylpentene copolymer, a propylene-hexene copolymer, a propylene-octene copolymer, a propylene-ethylene-butene copolymer, or the like, more preferably a propylene-ethylene copolymer, a propylene-butene copolymer, or a propylene-ethylene-butene copolymer, and even more preferably a propylene-ethylene-butene copolymer.

[0037] The propylene copolymer may be, for example, a polymer synthesized by the continuous gas phase polymerization method described in JP-A-2003-277412, and for example, FSX66E8 manufactured by Sumitomo Chemical Co., Ltd. may be used.

[0038] The melt flow rate (MFR) of the propylene copolymer (230°C, load 2.16 kg) is preferably 2.0 g / 10 min or more, more preferably 2.2 g / 10 min or more, even more preferably 2.4 g / 10 min or more, and preferably 8.0 g / 10 min or less, more preferably 7.5 g / 10 min or less, and even more preferably 7.0 g / 10 min or less. When the melt flow rate of the propylene copolymer is within the above range, workability and film strength are improved.

[0039] The melting point of the propylene copolymer is preferably 124° C. or higher, more preferably 126° C. or higher, even more preferably 128° C. or higher, still more preferably 130° C. or higher, and preferably 145° C. or lower, more preferably 142° C. or lower, and even more preferably 139° C. or lower. When the melting point of the propylene copolymer is within the above range, the heat sealability and stiffness can be improved.

[0040] The propylene copolymer (preferably a propylene-α-olefin copolymer) preferably contains at least one selected from a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of 1.0 mol% or less and a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol%, and more preferably contains a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol%.

[0041] The copolymerization ratio of the α-olefin in a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of the α-olefin of 1.0 mol% or less is preferably 0.9 mol% or less, more preferably 0.8 mol% or less, even more preferably 0.7 mol% or less, and is preferably 0.1 mol% or more, more preferably 0.15 mol% or more, even more preferably 0.2 mol% or more.

[0042] The copolymerization ratio of α-olefins in a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefins exceeding 1.0 mol% is preferably 1.1 mol% or more, more preferably 1.5 mol% or more, even more preferably 2 mol% or more, still more preferably 4 mol% or more, in total, and is preferably 16 mol% or less, more preferably 14 mol% or less, even more preferably 12 mol% or less, and still more preferably 10 mol% or less. Having the copolymerization ratio of α-olefins within the above range can improve heat sealability.

[0043] The copolymerization ratio of ethylene in the propylene-α-olefin copolymer (α-olefin having 2 or 4 to 10 carbon atoms) is preferably 1 mol% or more, more preferably 1.5 mol% or more, even more preferably 1.7 mol% or more, still more preferably 2 mol% or more, and is preferably 7 mol% or less, more preferably 6 mol% or less, even more preferably 5 mol% or less, and still more preferably 4 mol% or less. Having the copolymerization ratio of ethylene within the above range can improve heat sealability.

[0044] The copolymerization ratio of butene in the propylene-α-olefin copolymer (α-olefin having 2 or 4 to 10 carbon atoms) is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 4 mol% or more, still more preferably 5 mol% or more, and is preferably 12 mol% or less, more preferably 11 mol% or less, even more preferably 10 mol% or less, and still more preferably 9 mol% or less. Having the copolymerization ratio of butene within the above range can improve heat sealability.

[0045] The polyolefin resin composition constituting the intermediate layer preferably contains only a propylene copolymer, and more preferably contains a propylene homopolymer or a propylene copolymer and an olefin copolymer X different from the propylene homopolymer or the propylene copolymer.

[0046] The olefin copolymer X is preferably an olefin copolymer having 2 or 4 to 10 carbon atoms that does not contain a propylene monomer, more preferably an ethylene-butene copolymer, an ethylene-pentene copolymer, an ethylene-hexene copolymer, an ethylene-octene copolymer, a butene-pentene copolymer, a butene-hexene copolymer, or a butene-octene copolymer, still more preferably an ethylene-butene copolymer or an ethylene-pentene copolymer, and even more preferably an ethylene-butene copolymer.

[0047] The olefin copolymer X preferably has a predetermined MFR and melting point. The melt flow rate (MFR) (230°C, load 2.16 kg) of the olefin copolymer X is preferably higher than the MFRs of the propylene homopolymer and the propylene copolymer, more preferably 4 g / 10 min or more, even more preferably 5 g / 10 min or more, even more preferably 6 g / 10 min or more, more preferably 20 g / 10 min or less, even more preferably 18 g / 10 min or less, and even more preferably 16 g / 10 min or less. When the melt flow rate of the olefin copolymer X is within the above range, the MFR of the entire resin constituting the intermediate layer when a mixture with a propylene homopolymer or a propylene copolymer is used can be adjusted.

[0048] The melting point of the olefin copolymer X is preferably lower than the melting points of the propylene homopolymer and the propylene copolymer, and is more preferably 40° C. or higher, even more preferably 45° C. or higher, even more preferably 50° C. or higher, and particularly preferably 55° C. or higher, and is preferably 100° C. or lower, more preferably 95° C. or lower, even more preferably 90° C. or lower, and even more preferably 85° C. or lower. When the melting point of the olefin copolymer X is within the above range, the melting point of the entire resin constituting the intermediate layer when a mixture with a propylene homopolymer or a propylene copolymer is used can be adjusted.

[0049] When the polyolefin resin composition constituting the intermediate layer contains a propylene copolymer, the content of the propylene copolymer in the polyolefin resin composition constituting the intermediate layer is preferably 50% by weight or more, more preferably 52% by weight or more, even more preferably 54% by weight or more, still more preferably 56% by weight or more, particularly preferably 58% by weight or more, and is preferably 99% by weight or less, more preferably 97% by weight or less, even more preferably 95% by weight or less, and may be 100% by weight. By setting the content within the above range, the gas barrier property, heat resistance, and stiffness of the film can be improved.

[0050] When the polyolefin resin composition constituting the intermediate layer contains a propylene copolymer, the content of olefin copolymer X in the polyolefin resin composition constituting the intermediate layer is preferably 0 wt% or more, more preferably 1 wt% or more, even more preferably 5 wt% or more, still more preferably 10 wt% or more, preferably 50 wt% or less, more preferably 48 wt% or less, even more preferably 46 wt% or less, still more preferably 44 wt% or less, particularly preferably 40 wt% or less, 35 wt% or less, 25 wt% or less, or 20 wt% or less. By setting the content within the above ranges, when a mixture with a propylene copolymer is used, the MFR and melting point of the entire resin constituting the intermediate layer can be adjusted.

[0051] When the polyolefin resin composition constituting the intermediate layer contains a propylene homopolymer, the content of the propylene homopolymer in the polyolefin resin composition constituting the intermediate layer is preferably 1% by weight or more, more preferably 5% by weight or more, even more preferably 10% by weight or more, still more preferably 15% by weight or more, preferably 40% by weight or less, more preferably 35% by weight or less, and even more preferably 30% by weight or less.

[0052] When the polyolefin resin composition constituting the intermediate layer contains a propylene homopolymer, the content of the olefin copolymer X in the polyolefin resin composition constituting the intermediate layer is preferably 60% by weight or more, more preferably 65% ​​by weight or more, even more preferably 70% by weight or more, still more preferably 75% by weight or more, and preferably 99% by weight or less, more preferably 95% by weight or less, even more preferably 90% by weight or less, and still more preferably 85% by weight or less. When the content is within the above range, the MFR and melting point of the entire resin constituting the intermediate layer can be adjusted when a mixture with a propylene homopolymer is used.

[0053] In one embodiment of the present invention, the content of the propylene copolymer constituting the intermediate layer is preferably more than 60% by mass, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, even more preferably 75% by mass or more, and preferably 100% by mass, 99% by mass or less, or 95% by mass or less, in the polyolefin resin composition constituting the intermediate layer. If the amount of the propylene copolymer is too small, the adhesive strength between the layers constituting the stretched laminated polyolefin resin film may be insufficient, making it impossible to obtain sufficient heat seal strength. On the other hand, if the amount of the propylene copolymer is too large, there is no problem. When the content of the propylene copolymer in the intermediate layer is in the upper range, oxygen barrier properties and heat sealability can be improved.

[0054] In one embodiment of the present invention, it is particularly preferred that the polyolefin resin composition constituting the intermediate layer contains 100% by weight of a propylene copolymer. In one embodiment of the present invention, it is particularly preferred that the polyolefin resin composition constituting the intermediate layer contains 100% by weight of a propylene copolymer and an olefin copolymer X. In one embodiment of the present invention, it is particularly preferred that the polyolefin resin composition constituting the intermediate layer contains 100% by weight of a propylene homopolymer and an olefin copolymer X.

[0055] In one aspect of the present invention, the polyolefin-based resin composition constituting the intermediate layer preferably does not contain a propylene-α-olefin copolymer (the α-olefin having 2 or 4 to 10 carbon atoms) in which the copolymerization ratio of the α-olefin is 1.0 mol % or less.

[0056] The propylene copolymer used in the intermediate layer has excellent mechanical strength, such as impact strength and tear resistance, as well as low-temperature properties and weather resistance. The incorporation of such a component can impart excellent properties to the stretched laminated polyolefin resin film. However, since the propylene copolymer has a structure in which different α-olefins are randomly introduced as second and third components into the molecular chain of the main α-olefin, crystallization is suppressed, resulting in lower crystallinity compared to α-olefin homopolymers such as homopolypropylene. Consequently, the incorporation of a propylene copolymer results in a decrease in the stiffness of the film. On the other hand, if the amorphous portion is too small, the film becomes hard and difficult to stretch, making it difficult to obtain sufficient heat seal strength. Therefore, from these perspectives, it is preferable to incorporate a propylene copolymer into the intermediate layer to obtain a laminated film with appropriate stiffness and the ability to stretch under load.

[0057] Heat-sealing layer The heat-sealing layer is a layer necessary for producing a package by overlapping two films with the stretched laminated polyolefin resin film on the inside and heat-sealing them. The heat-sealing layer is composed of a polyolefin resin composition containing a polyolefin resin having a melting point of 150°C or less. The heat-sealing layer may be a single layer or two or more layers, and is preferably a single layer.

[0058] The polyolefin resin having a melting point of 150° C. or less preferably contains one or more types of propylene copolymers, more preferably two or more types of propylene copolymers, and even more preferably two types of propylene copolymers.

[0059] The melt flow rate (MFR) of the propylene copolymer is preferably 2.5 g / 10 min or more, more preferably 2.7 g / 10 min or more, even more preferably 3.0 g / 10 min or more, and preferably 20 g / 10 min or less, more preferably 17 g / 10 min or less, and even more preferably 12 g / 10 min or less. When the melt flow rate of the propylene copolymer is in the above range, the heat sealability of the film becomes good.

[0060] In order to provide the laminated film of the present invention with sufficient heat seal strength, the lower limit of the melting point of the polyolefin resin (preferably a propylene copolymer) constituting the heat-sealable layer is preferably 60°C, more preferably 65°C, and even more preferably 70°C. If the lower limit of the melting point is too low, the heat resistance of the heat-sealed portion may be poor, while if the melting point is too high, improvement in heat seal strength may not be expected. Therefore, the upper limit of the melting point is preferably 150°C, more preferably 140°C, and even more preferably 135°C. If the lower limit of the melting point is too low, the heat resistance of the heat-sealed portion may be poor, while if the melting point is too high, improvement in heat seal strength may not be expected.

[0061] The propylene copolymer is preferably a propylene-α-olefin copolymer, and may be a random copolymer or a block copolymer, preferably a random copolymer. The α-olefin is preferably an α-olefin monomer having 2 or 4 to 10 carbon atoms, and more preferably ethylene, butene, pentene, hexene, octene, decene, etc.

[0062] The propylene copolymer (preferably a propylene-α-olefin copolymer) is preferably a propylene-ethylene copolymer, a propylene-butene copolymer, a propylene-pentene copolymer, a propylene-methylpentene copolymer, a propylene-hexene copolymer, a propylene-octene copolymer, a propylene-ethylene-butene copolymer, or the like, more preferably a propylene-ethylene copolymer, a propylene-butene copolymer, or a propylene-ethylene-butene copolymer, and even more preferably a propylene-butene copolymer or a propylene-ethylene-butene copolymer.

[0063] Examples of the propylene copolymer include polymers synthesized by the continuous gas phase polymerization method described in JP-A-2003-277412, and for example, FSX66E8 manufactured by Sumitomo Chemical Co., Ltd. and SP8931 manufactured by Sumitomo Chemical Co., Ltd. can be used.

[0064] The propylene copolymer preferably contains at least one selected from propylene-α-olefin copolymers (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of 1.0 mol% or less and propylene-α-olefin copolymers (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol%, and more preferably contains a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol%.

[0065] The propylene copolymer preferably contains two or more propylene-α-olefin copolymers (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin exceeding 1.0 mol%, and more preferably contains a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin exceeding 1.0 mol% and not more than 15 mol%, and a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin exceeding 15 mol% and not more than 45 mol%.

[0066] The copolymerization ratio of α-olefins in a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefins exceeding 1.0 mol% and not more than 15 mol% is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 4 mol% or more, still more preferably 5 mol% or more, in total, and is preferably 15 mol% or less, more preferably 13 mol% or less, even more preferably 11 mol% or less, and still more preferably 10 mol% or less.

[0067] The copolymerization ratio of ethylene in a propylene-α-olefin copolymer (α-olefin having 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol% and not more than 15 mol% is preferably 1 mol% or more, more preferably 1.5 mol% or more, even more preferably 1.7 mol% or more, still more preferably 2 mol% or more, and preferably 7 mol% or less, more preferably 6 mol% or less, even more preferably 5 mol% or less, and still more preferably 4 mol% or less.

[0068] The copolymerization ratio of butene in a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefin of more than 1.0 mol% and 15 mol% or less is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 4 mol% or more, still more preferably 5 mol% or more, and preferably 12 mol% or less, more preferably 11 mol% or less, even more preferably 10 mol% or less, and still more preferably 9 mol% or less.

[0069] The copolymerization ratio of α-olefins in a propylene-α-olefin copolymer (the α-olefin has 2 or 4 to 10 carbon atoms) having a copolymerization ratio of α-olefins of more than 15 mol% and not more than 45 mol% is preferably 18 mol% or more, more preferably 21 mol% or more, even more preferably 24 mol% or more, still more preferably 27 mol% or more, in total, and is preferably 45 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and still more preferably 33 mol% or less.

[0070] The copolymerization ratio of butene in a propylene-α-olefin copolymer (the α-olefin having 2 or 4 to 10 carbon atoms) having an α-olefin copolymerization ratio of more than 15 mol% and not more than 45 mol% is preferably 15 mol% or more, more preferably 18 mol% or more, even more preferably 21 mol% or more, still more preferably 24 mol% or more, and is preferably 45 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, and still more preferably 33 mol% or less. While there are no particular limitations on the upper limit of the butene content, if the butene content is too high, the film surface may become sticky and the slipperiness and blocking resistance may decrease. Therefore, the upper limit may be determined appropriately within a range that does not cause such defects.

[0071] A propylene-α-olefin copolymer having a copolymerization ratio of α-olefin of more than 1.0 mol% and not more than 15 mol% (the α-olefin has 2 or 4 to 10 carbon atoms) is preferably a propylene-ethylene-butene copolymer. A propylene-α-olefin copolymer having a copolymerization ratio of α-olefin of more than 15 mol% and not more than 45 mol% (the α-olefin has 2 or 4 to 10 carbon atoms) is preferably a propylene-butene copolymer.

[0072] The polyolefin resin composition containing the polyolefin resin constituting the heat-sealable layer contains 60% by weight or more of a propylene copolymer, preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, still more preferably 95% by weight or more, and particularly preferably 100% by weight.

[0073] The polyolefin resin composition comprising the polyolefin resin that constitutes the heat-sealable layer preferably contains 1 to 50% by weight, more preferably 5 to 45% by weight, and even more preferably 10 to 40% by weight of a propylene-α-olefin copolymer (the α-olefin having a copolymerization ratio of 1.0 mol% to 15 mol% and having 2 or 4 to 10 carbon atoms) in a proportion of more than 1.0 mol% to 15 mol%. If the blending amount of the propylene-α-olefin copolymer having a copolymerization ratio of α-olefin of more than 1.0 mol% to 15 mol% is too high, the fusion strength during sealing may be low, making it difficult to obtain sufficient heat seal strength. On the other hand, if the blending amount is too low, there is no particular problem with heat seal performance, but if the amount of antiblocking agent added is insufficient, there is a concern that handling during use may be impaired.

[0074] The polyolefin resin composition comprising the polyolefin resin that constitutes the heat-sealable layer preferably contains 50% by weight or more and 99% by weight or less, more preferably 55% by weight or more and 95% by weight or less, and even more preferably 60% by weight or more and 90% by weight or less, of a propylene-α-olefin copolymer (α-olefin having a copolymerization ratio of 15 mol% or more and 45 mol% or less) having an α-olefin of 2 or 4 to 10 carbon atoms. If the blending amount of the propylene-α-olefin copolymer having an α-olefin of 15 mol% or more and 45 mol% or less is too low, the fusion strength during sealing may be low, making it difficult to obtain sufficient heat seal strength. On the other hand, if the blending amount is too high, there is no particular problem with heat seal performance, but if the amount of antiblocking agent added is insufficient, there is a concern that handling during use may be impaired.

[0075] Various additives and fillers may be added to each layer constituting the stretched laminated polyolefin resin film of the present invention as needed, provided that the properties of each layer are not impaired. Examples include heat stabilizers, antioxidants, light stabilizers, antistatic agents, lubricants, nucleating agents, flame retardants, pigments, dyes, calcium carbonate, barium sulfate, magnesium hydroxide, mica, talc, clay, zinc oxide, magnesium oxide, aluminum oxide, antibacterial agents, and additives that impart biodegradability. Furthermore, thermoplastic resins, thermoplastic elastomers, rubbers, hydrocarbon resins, petroleum resins, and the like other than those mentioned above may also be added to the laminated film, provided that the properties of the laminated film are not impaired.

[0076] The stretched laminated polyolefin resin film of the present invention may be subjected to a surface treatment as needed (for example, to improve printability) as long as the film's properties are not impaired. Examples of surface treatment methods include corona discharge treatment, plasma treatment, flame treatment, and acid treatment. Among the above-mentioned methods, corona discharge treatment, plasma treatment, and flame treatment are preferred because they can be performed continuously and can be easily carried out before the winding step during film production. Corona discharge treatment is particularly recommended as a means of improving wetting tension.

[0077] The stretched laminated polyolefin resin film of the present invention preferably satisfies the relationship of thickness of the base layer > thickness of the intermediate layer > thickness of the heat-sealable layer. When this relationship is satisfied, it is possible to improve heat resistance and stiffness.

[0078] In the stretched laminated polyolefin resin film of the present invention, the ratio of the base layer is preferably 30% to 94% (more preferably 40% to 88% and even more preferably 50% to 82%) of the total thickness of the stretched laminated polyolefin resin film, the ratio of the heat-sealable layer is preferably 1% to 20% (more preferably 2% to 15%, even more preferably 2% to 10%, and even more preferably 4% to 10%) of the total thickness of the stretched laminated polyolefin resin film, and the ratio of the intermediate layer is preferably 5% to less than 50% (more preferably 10% to 45%, and even more preferably 15% to 40%) of the total thickness of the stretched laminated polyolefin resin film. If the ratio of the base layer is less than 30%, the ratio of the heat-sealable layer is more than 20%, and the ratio of the intermediate layer is 50% or more, the laminated film tends to have difficulty in achieving a firm feel, which is undesirable from the viewpoint of product handling. If the ratio of the base layer exceeds 94%, the ratio of the heat-sealable layer is less than 1%, and the ratio of the intermediate layer is less than 5%, it may be difficult to obtain the desired heat seal strength.

[0079] In the present invention, the thickness of the film is arbitrarily set according to each application, but the lower limit is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more. On the other hand, the upper limit of the thickness is preferably 300 μm or less, more preferably 250 μm or less, even more preferably 200 μm or less, and particularly preferably 150 μm or less. If the thickness is thin, handling tends to be poor. On the other hand, if the thickness is thick, not only is there a problem in terms of cost, but also poor flatness due to curling tends to occur when wound into a roll and stored. The preferred film thickness range in consideration of volume reduction of the film and productivity during processing will be described later.

[0080] A stretched laminated polyolefin resin film having no gas barrier layer is preferably transparent. From the viewpoint of visibility of contents, the haze of the stretched laminated polyolefin resin film of the present invention is preferably 6% or less, more preferably 5% or less, even more preferably 4% or less, and preferably 0.1% or more, 0.5% or more, or 1% or more. Haze tends to deteriorate, for example, when the stretching temperature or heat setting temperature is too high, when the cooling roll (CR) temperature is high and the cooling rate of the stretched raw sheet is slow, or when there is too much low molecular weight, so it can be controlled within the above range by adjusting these.

[0081] The configuration of the stretched laminated polyolefin resin film according to the present invention is not particularly limited as long as it comprises the above-mentioned substrate layer, intermediate layer, and heat-sealing layer, and the present invention also includes an embodiment in which a polypropylene resin layer of the same type as the constituent resin of the substrate layer or another resin layer for imparting various properties to the laminated film (e.g., a gas barrier resin layer such as a saponified ethylene-vinyl acetate copolymer or polyvinyl alcohol) is laminated on the surface of the substrate layer. Furthermore, the lamination position of the other resin layer is not limited as long as the properties of the laminated film are not impaired, and for example, the above-mentioned other layer can be provided between the substrate layer and the intermediate layer, or between the intermediate layer and the heat-sealing layer.

[0082] In particular, it is preferable that the stretched laminated polyolefin resin film of the present invention comprises a base layer, an intermediate layer, and a heat-sealing layer in this order, with no other layer present between the base layer and the intermediate layer, and no other layer present between the intermediate layer and the heat-sealing layer.

[0083] The method for producing the stretched laminated polyolefin resin film of the present invention is not particularly limited, and it can be produced by any conventionally known method. For example, it can be produced by melt-laminating using an extruder suitable for the number of layers by a T-die method, inflation method, etc., and then cooling by a cooling roll method, water cooling method, or air cooling method to produce an unstretched laminated film, and then stretching by a sequential biaxial stretching method, simultaneous biaxial stretching method, tube stretching method, etc. Among these, the sequential biaxial stretching method is particularly preferred from the viewpoint of improving flatness, dimensional stability, heat resistance, thickness unevenness, etc.

[0084] In the sequential biaxial stretching method, for example, polypropylene resin is heated and melted in a single-screw or twin-screw extruder so that the resin temperature is 200°C or higher and 280°C or lower (preferably 220°C or higher, more preferably 240°C or higher), formed into a sheet using a T-die, and extruded onto a chill roll at a temperature of 10°C or higher and 100°C or lower (preferably 80°C or lower, more preferably 60°C or lower, and even more preferably 40°C or lower) to obtain an unstretched sheet. Next, the film is roll-stretched in the machine direction (MD direction) at 120°C or higher and 165°C or lower (preferably 120°C or higher and 150°C or lower, more preferably 122°C or higher and 135°C or lower) to 3.0 times or higher and 8.0 times or lower (preferably 3.5 times or higher and 7.5 times or lower, more preferably 4.0 times or higher and 7.0 times or lower), and subsequently, after preheating in a tenter, it can be stretched in the transverse direction (TD direction) at 155°C or higher and 175°C or lower (preferably 157°C or higher and 170°C or lower, more preferably 159°C or higher and 165°C or lower) to 4.0 times or higher and 20.0 times or lower (preferably 5.0 times or higher and 15.0 times or lower, more preferably 6.0 times or higher and 10.0 times or lower). Furthermore, after biaxial stretching, the film can be subjected to heat setting treatment at a temperature of 165°C or higher and 175°C or lower (preferably 166°C or higher and 174°C or lower, more preferably 167°C or higher and 173°C or lower) while relaxing by 1% or higher and 15% or lower (preferably 2% or higher and 12% or lower, more preferably 3% or higher and 9% or lower).

[0085] [Gas Barrier Layer] In the present invention, the film has a gas barrier layer on the surface of the base layer. As the gas barrier layer, it is preferable to laminate either a coating layer (A) mainly composed of an organic substance or an inorganic thin film layer (B) mainly composed of an inorganic substance, as described below. Furthermore, in order to enhance the barrier properties of the gas barrier layer, an anchor coat (C) or a protective layer (D), as described below, can also be laminated in combination.

[0086] The stretched laminated polyolefin resin film of the present invention preferably has a configuration of coating layer / substrate layer / intermediate layer / thermal adhesive layer, inorganic thin film layer / substrate layer / intermediate layer / thermal adhesive layer, inorganic thin film layer / anchor coat layer / substrate layer / intermediate layer / thermal adhesive layer, protective layer / inorganic thin film layer / anchor coat layer / substrate layer / intermediate layer / thermal adhesive layer, etc. The gas barrier property is higher in the coating layer than in the inorganic thin film layer, and tends to be higher when a protective layer and / or anchor coat layer is further provided.

[0087] [Coating layer (A)] In the present invention, it is preferable to provide a coating layer (A) as a gas barrier layer. However, in the present invention, it is necessary to design the coating layer (A) with due consideration given to the environmental impact, such as increased costs due to the additional steps and difficulty in recycling depending on the coating layer's thickness.

[0088] The gas barrier layer is preferably a coating layer containing one or more of a polyvinyl alcohol resin, a polyester resin, a polyurethane resin, or an inorganic layered compound. The resin composition used for the coating layer (A) formed on the surface of the laminate film of the present invention is preferably a polyvinyl alcohol polymer, a polyester resin, or a polyurethane resin. Among these, polyvinyl alcohol polymers are more preferred from the viewpoint of improving barrier performance. Polyvinyl alcohol polymers are primarily composed of vinyl alcohol units, and are expected to exhibit significant improvements in barrier performance due to their high cohesion properties resulting from hydrogen-bonded structures. The polymerization degree and saponification degree of the polyvinyl alcohol polymer are determined based on the desired gas barrier properties and the viscosity of the coating aqueous solution. The polymerization degree is preferably 2600 or less, more preferably 2500 or less, and even more preferably 2400 or less, from the viewpoint of coating workability. A saponification degree of less than 90% does not provide sufficient oxygen gas barrier properties under high humidity conditions, while a saponification degree of more than 99.7% makes it difficult to prepare the aqueous solution and is prone to gelation, making it unsuitable for industrial production. Therefore, the saponification degree is preferably 90 to 99.7%, more preferably 93 to 99%. In the present invention, various copolymerized or modified polyvinyl alcohol polymers, such as polyvinyl alcohol polymers copolymerized with ethylene and silanol-modified polyvinyl alcohol polymers, can also be used within the range that does not impair processability or productivity.

[0089] The coating layer (A) of the present invention may contain an inorganic layered compound. The presence of the inorganic layered compound can be expected to provide a labyrinth effect against gases, improving gas barrier properties. Furthermore, the addition of the inorganic layered compound can suppress humidity dependency of gas barrier properties. Examples of materials include clay minerals (including synthetic products thereof) such as smectite, kaolin, mica, hydrotalcite, and chlorite. Specific examples include montmorillonite, beidellite, saponite, hectorite, sauconite, stevensite, kaolinite, nacrite, dickite, halloysite, hydrated halloysite, tetrasilylic mica, sodium taeniolite, muscovite, margarite, phlogopite, talc, antigorite, chrysotile, pyrophyllite, vermiculite, xanthophyllite, and chlorite. Furthermore, scaly silica and the like can also be used as the inorganic layered compound. These may be used alone or in combination of two or more. Among these, smectite (including synthetic products thereof) is particularly preferred because it has a high effect of improving the water vapor barrier property.

[0090] Furthermore, inorganic layered compounds containing metal ions, particularly iron ions, having redox properties are preferred. Among these, montmorillonite, a type of smectite, is preferred from the viewpoint of coating suitability and gas barrier properties. As montmorillonite, known compounds that have been conventionally used in gas barrier agents can be used. For example, compounds represented by the following general formula: (X, Y) 2～3 Z4O 10 (OH)mHO(Wω) (In the formula, X represents Al, Fe(III), or Cr(III). Y represents Mg, Fe(II), Mn(II), Ni, Zn, or Li. Z represents Si or Al. W represents K, Na, or Ca. HO represents interlayer water. m and ω represent positive real numbers.) Among these, those in which W in the formula is Na are preferred because they cleave in an aqueous medium.

[0091] The size and shape of the inorganic layered compound are not particularly limited, but the particle size (major axis) is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. If the particle size is larger than 5 μm, dispersibility will be poor, and as a result, the coatability and coat appearance of the coating layer (A) may be deteriorated. On the other hand, the aspect ratio is preferably 50 to 5000, more preferably 100 to 4000, and even more preferably 200 to 3000.

[0092] The blending ratio of the resin composition to the inorganic layered compound in the coating layer of the present invention (resin composition / inorganic layered compound) is preferably 75 / 25 to 35 / 65 (wt %), more preferably 70 / 30 to 40 / 60 (wt %), and even more preferably 65 / 35 to 45 / 55 (wt %). If the blending ratio of the inorganic layered compound is less than 25 wt %, the barrier performance may be insufficient. On the other hand, if it is more than 65 wt %, the dispersibility may be poor, which may result in poor coatability and poor adhesion.

[0093] In order to improve the cohesive strength of the film and the heat-and-moisture resistant adhesion, various crosslinking agents may be blended into the coating layer (A) of the present invention, as long as they do not impair gas barrier properties or productivity. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, isocyanate compounds, etc. Among them, by blending a silicon-based crosslinking agent, a crosslinking reaction can be caused with a resin composition having a hydroxyl group or an inorganic thin film layer, and from the viewpoint of improving water-resistant adhesion, silicon-based crosslinking agents are particularly preferred. Commonly used silicon-based crosslinking agents include metal alkoxides and silane coupling agents. Metal alkoxides are represented by the general formula M(OR) n (M: metals such as Si and Al, R: CH ３ , C ２ H ５ Specifically, tetraethoxysilane [Si(OC ２ H ５ ) ４ ], triisopropoxyaluminum Al[OCH(CH ３ ) ２ ] ３Examples of silane coupling agents include those having an epoxy group such as 3-glycidoxypropyltrimethoxysilane, those having an amino group such as 3-aminopropyltrimethoxysilane, those having a mercapto group such as 3-mercaptopropyltrimethoxysilane, those having an isocyanate group such as 3-isocyanatepropyltriethoxysilane, and tris-(3-trimethoxysilylpropyl)isocyanurate. In addition, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc. may be used in combination as crosslinking agents. However, when emphasis is placed on recyclability, the amount of crosslinking agent added must be considered.

[0094] When a crosslinking agent is incorporated, its amount in the composition constituting the coating layer is preferably 0.1 to 50 wt %, more preferably 0.5 to 50 wt %, and even more preferably 1.0 to 50 wt %. By maintaining the amount in this range, the film hardens and the cohesive strength improves, resulting in a film with excellent water-resistant adhesion. If the amount of crosslinking agent exceeds 50 wt %, the amount of uncrosslinked portions increases, or the film hardens due to excessive hardening, which may conversely result in a decrease in adhesion. On the other hand, if the amount is less than 0.1 wt %, sufficient cohesive strength may not be obtained.

[0095] In the present invention, the haze of the film after lamination of the coating layer (A) is preferably 20% or less, more preferably 18% or less, and even more preferably 16% or less, from the viewpoint of visibility of the contents. If the haze is greater than 20%, transparency will be significantly reduced and there is a concern that it will also affect the surface irregularities, which may lead to poor appearance in subsequent printing processes, etc. The haze can be adjusted by the composition ratio of the coating layer (A), solvent conditions, film thickness, etc. Here, the haze is evaluated in accordance with JIS K7136 using a turbidity meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0096] The coating weight of the coating layer (A) is 0.10 to 3.0 (g / m 2 The coating amount of the coating layer (A) is more preferably 0.15 (g / m 2 ) or more, more preferably 0.20 (g / m 2 ) or more, and even more preferably 0.25 (g / m2 ) or more, and preferably 2.5 (g / m 2 ) or less, more preferably 2.0 (g / m 2 ) or less, more preferably 1.5 (g / m 2 The coating amount of the coating layer (A) is 3.0 (g / m 2 ), the gas barrier properties are improved, but the cohesive force inside the coating layer becomes insufficient and the uniformity of the coating layer also decreases, which can cause unevenness (increased haze, whitening) or defects in the coat appearance, or can prevent the gas barrier properties and adhesive properties from being fully exhibited. In terms of processability, a thick film thickness can also cause blocking. Furthermore, there is a concern that this will have a negative effect on the recyclability of the film, and the amount of raw materials, solvents, etc. used will also increase, which will increase the environmental impact. On the other hand, if the coating layer (A) adhesion amount is 0.10 (g / m), 2 If the thickness is less than 1 / 2 mm, sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0097] The coating method for the resin composition for the coating layer is not particularly limited as long as it is a method that can coat the surface of a film to form a layer, and for example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0098] When forming the coating layer (A), it is preferable to apply the resin composition for the coating layer, pre-dry it at a relatively low temperature to evaporate the solvent, and then dry it at a high temperature, as this will result in a uniform film. The pre-drying temperature is preferably 80 to 110°C, more preferably 85 to 105°C, and even more preferably 90 to 100°C. If the pre-drying temperature is less than 80°C, the coating layer may not be sufficiently dried. If the pre-drying temperature is higher than 110°C, the coating layer may dry before it has spread, resulting in a poor appearance.

[0099] On the other hand, the main drying temperature is preferably 110 to 140°C, more preferably 115 to 135°C, and even more preferably 120 to 130°C. If the main drying temperature is less than 110°C, film formation of the coating layer (A) will not proceed, resulting in a decrease in cohesive strength and adhesiveness, which may adversely affect the barrier properties. If the temperature exceeds 140°C, the film may be subjected to too much heat, making it brittle and causing large wrinkles due to heat shrinkage.

[0100] The preferred drying time for preliminary drying is 3.0 to 10.0 seconds, more preferably 3.5 to 9.5 seconds, and even more preferably 4.0 to 9.0 seconds. The preferred drying time for main drying is 3.0 to 10.0 seconds, more preferably 3.5 to 9.5 seconds, and even more preferably 4.0 to 9.0 seconds. However, care must be taken as drying conditions vary depending on the type of heat transfer medium and the intake and exhaust conditions of the drying furnace. Furthermore, additional heat treatment for 1 to 4 days at a temperature as low as possible, specifically a temperature range of 40 to 60°C, separate from drying, is also more effective in accelerating the formation of the coating layer (A).

[0101] [Inorganic Thin Film Layer (B)] In the present invention, it is preferable to provide an inorganic thin film layer (B) on the surface of the base layer of the film as a gas barrier layer. The inorganic thin film layer (B) is preferably a thin film made of a metal or an inorganic oxide. The material for forming the inorganic thin film layer is not particularly limited as long as it can be formed into a thin film. From the viewpoint of gas barrier properties, examples include metals such as aluminum, and inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and mixtures of silicon oxide and aluminum oxide. That is, the gas barrier layer is preferably an inorganic thin film layer made of any one of aluminum, aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide, and more preferably an inorganic thin film layer made of any one of aluminum, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide. In particular, a composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint of achieving both flexibility and density of the thin film layer. In this composite oxide, the mixing ratio of silicon oxide to aluminum oxide is preferably in the range of 20 to 70 wt % Al, more preferably in the range of 25 to 65 wt %, and even more preferably in the range of 30 to 60 wt %, as the mass ratio of the metal components (Al / (Al+Si)×100). If the Al ratio is less than 20 wt %, the water vapor barrier property may be reduced. On the other hand, if the Al ratio exceeds 70 wt %, the inorganic thin film layer tends to become hard, and there is a risk that the film will be destroyed during secondary processing such as printing or lamination, resulting in a reduction in gas barrier property. Note that silicon oxide referred to here means various silicon oxides such as SiO and SiO2 or mixtures thereof, and aluminum oxide means various aluminum oxides such as AlO and Al2O3 or mixtures thereof.

[0102] The thickness of the inorganic thin film layer (B) is usually 1 to 100 nm, preferably 5 to 95 nm, and more preferably 7 to 90 nm. If the thickness of the inorganic thin film layer (B) is less than 1 nm, it may be difficult to obtain satisfactory gas barrier properties. On the other hand, even if the thickness is excessively thick, exceeding 100 nm, the corresponding improvement in gas barrier properties is not obtained, and it is actually disadvantageous in terms of flex resistance and manufacturing costs. In particular, the thickness of the aluminum thin film layer is, for example, 20 to 100 nm, preferably 30 to 90 nm, more preferably 40 to 80 nm, and even more preferably 50 to 80 nm. The thickness of the silicon oxide thin film layer is, for example, 10 to 80 nm, preferably 20 to 70 nm, and more preferably 30 to 60 nm. The thickness of the silicon oxide and aluminum oxide layers is, for example, 5 to 60 nm, preferably 10 to 50 nm, and more preferably 15 to 40 nm.

[0103] The method for forming the inorganic thin film layer (B) is not particularly limited, and any known vapor deposition method may be appropriately employed, such as physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD). A typical method for forming the inorganic thin film layer (B) will be described below, taking silicon oxide / aluminum oxide-based thin films as an example. For example, when using vacuum deposition, a mixture of SiO and AlO, or a mixture of SiO and Al, is preferably used as the vapor deposition source. These vapor deposition sources are typically particles, and the particle size is preferably such that the pressure during vapor deposition does not change, with a preferred particle diameter being 1 mm to 5 mm. Heating methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating can be employed. Furthermore, reactive vapor deposition using reactive gases such as oxygen, nitrogen, hydrogen, argon, carbon dioxide, and water vapor, or ozone addition or ion-assisted deposition can also be employed. Furthermore, the film formation conditions can be changed as desired by applying a bias to the deposition target (the laminated film to be deposited), heating or cooling the deposition target, etc. The deposition material, reactive gas, bias, heating / cooling, etc. of the deposition target can be changed in the same way when the sputtering method or the CVD method is adopted.

[0104] [Anchor Coat Layer (C)] An anchor coat layer is preferably laminated between the film and the gas barrier layer. In the present invention, the anchor coat layer (C) is preferably provided as an auxiliary layer to ensure sufficient gas barrier properties and adhesiveness when the aforementioned gas barrier layer is laminated. The provision of the anchor coat layer can suppress the exposure of oligomers and antiblocking agents from the polypropylene resin. Furthermore, when laminating other layers on the anchor coat layer (C), it can also enhance the adhesion between layers. In particular, when forming an inorganic thin film layer, not only adhesion is improved, but surface smoothing can also be expected to promote the formation of the inorganic layer and improve gas barrier properties. Additionally, using a material with a certain level of gas barrier properties (hereinafter referred to as gas barrier auxiliary properties) for the anchor coat layer (C) itself can significantly improve the gas barrier performance of the film when the aforementioned gas barrier layer is laminated. Furthermore, the anchor coat layer (C) prevents hot water from penetrating the substrate, thereby reducing film whitening after boiling or retorting.

[0105] The gas barrier properties of the film when only the anchor coat layer (C) is laminated are as follows: oxygen permeability is 10,000 ml / m under an environment of 23°C x 65% RH 2 It is preferable that the viscosity is 9000 ml / m or less, since good gas barrier properties are exhibited after laminating the gas barrier layer. 2 d MPa or less, more preferably 8000 ml / m 2 ・d・MPa or less. Oxygen permeability is 10,000 ml / m 2 If the modulus exceeds d·MPa, sufficient barrier performance cannot be obtained even after laminating the gas barrier layer, making it difficult to use in applications where high gas barrier properties are required.

[0106] In the present invention, the amount of the anchor coat layer (C) deposited is 0.10 to 1.0 g / m 2This allows the anchor coat layer (C) to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. Furthermore, the anchor coat layer (C) contributes to suppressing oligomer exposure, stabilizing haze after retort moist heat treatment. The amount of adhesion of the anchor coat layer (C) is preferably 0.15 g / m 2 More preferably, 0.20 g / m 2 More preferably, 0.35 g / m 2 or more, and preferably 0.950 g / m 2 or less, more preferably 0.90 g / m 2 More preferably 0.85 g / m or less 2 The adhesion amount of the anchor coat layer (C) is 1.0 g / m or less. 2 If the thickness exceeds 0.10 g / m, the gas barrier property is improved, but the cohesive force inside the anchor coat layer becomes insufficient and the uniformity of the anchor coat layer is also reduced, resulting in unevenness and defects in the coat appearance. In terms of processability, a thick film thickness may cause blocking or increase production costs. Furthermore, there is a concern that it may have a negative effect on the recyclability of the film, and the amount of raw materials, solvents, etc. used will increase, resulting in a greater environmental impact. On the other hand, if the thickness of the anchor coat layer (C) is 0.10 g / m, 2 If it is less than this, there is a risk that sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0107] Resin compositions used in the anchor coat layer (C) of the present invention include urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based, and other resins to which epoxy-based, isocyanate-based, melamine-based, and other curing agents have been added. They may also contain crosslinking agents such as silicon-based crosslinkers, oxazoline compounds, carbodiimide compounds, and epoxy compounds. Urethane-based resins are particularly preferred because they offer barrier performance due to the high cohesive properties of the urethane bond itself, as well as the interaction of polar groups with the gas barrier layer and flexibility due to the presence of amorphous portions, thereby reducing damage even when subjected to bending loads. Polyester resins are also suitable, as they are expected to have similar effects. In the present invention, polyurethanes containing polyester-based resins and isocyanate-based curing agents as constituent components are particularly preferred. Furthermore, the addition of a silicon-based crosslinking agent is even more preferred from the viewpoint of improving adhesion.

[0108] In terms of gas barrier assisting properties, the urethane resin used in the anchor coat layer (C) of the present invention is preferably a urethane resin containing an aromatic or araliphatic diisocyanate component as a main constituent. Among these, it is particularly preferable to contain a metaxylylene diisocyanate component. By using such a resin, the cohesive strength of the urethane bond can be further enhanced due to the stacking effect between aromatic rings, resulting in good gas barrier assisting properties.

[0109] In the present invention, the proportion of aromatic or araliphatic diisocyanate in the urethane resin used in the anchor coat layer (C) is preferably 50 mol% or more (50 to 100 mol%) based on 100 mol% of the polyisocyanate component. The total proportion of aromatic or araliphatic diisocyanate is more preferably 60 to 100 mol%, even more preferably 70 to 100 mol%, and even more preferably 80 to 100 mol%. If the total proportion of aromatic or araliphatic diisocyanate is less than 50 mol%, good gas barrier assist properties may not be obtained.

[0110] The urethane resin used in the anchor coat layer (C) of the present invention may be blended with various crosslinking agents in order to improve the cohesive strength of the film and improve the adhesion resistance to wet heat.As crosslinking agents, for example, silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc. can be exemplified.Among them, silicon-based crosslinking agents are particularly preferred, because by blending silicon-based crosslinking agents, they can improve the water-resistant adhesion with inorganic thin film layers in particular.Other crosslinking agents may also be used in combination with oxazoline compounds, carbodiimide compounds, epoxy compounds, etc.

[0111] As the silicon-based crosslinking agent, a silane coupling agent is preferred from the viewpoint of crosslinking between an inorganic substance and an organic substance. Examples of the silane coupling agent include hydrolyzable alkoxysilane compounds, such as halogen-containing alkoxysilanes (chloro C2-4 alkyl tri C1-4 alkoxysilanes such as 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, and 3-chloropropyltriethoxysilane), and alkoxysilanes having an epoxy group (2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, and the like). trimethoxysilane, glycidyloxy C2-4 alkyltri C1-4 alkoxysilanes such as 3-glycidyloxypropyltriethoxysilane, glycidyloxydi C2-4 alkyldi C1-4 alkoxysilanes such as 3-glycidyloxypropylmethyldimethoxysilane and 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyl (epoxycycloalkyl)C2-4 alkyltriC1-4 alkoxysilanes such as 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc.], alkoxysilanes having an amino group (aminoC2-4 alkyltriC1-4 alkoxysilanes such as 2-aminoethyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc., aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, etc., 2-[N-(2-aminoethyl)amino] (2-aminoC2-4 alkyl)aminoC2-4 alkyltriC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, and 3-[N-(2-aminoethyl)amino]propyltriethoxysilane; (aminoC2-4 alkyl)aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane and 3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane;Alkoxysilanes having a mercapto group (mercapto C2-4 alkyltri C1-4 alkoxysilanes such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc., mercaptodi C2-4 alkyldi C1-4 alkoxysilanes such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc.), alkoxysilanes having a vinyl group (vinyltri C1-4 alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.), ethylene Examples of suitable silane coupling agents include alkoxysilanes having a functionally unsaturated bond group [(meth)acryloxyC2-4 alkyltriC1-4 alkoxysilanes such as 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane; and (meth)acryloxydiC2-4 alkyldiC1-4 alkoxysilanes such as 3-(meth)acryloxypropylmethyldimethoxysilane and 3-(meth)acryloxypropylmethyldiethoxysilane]. These silane coupling agents can be used alone or in combination of two or more. Of these silane coupling agents, silane coupling agents having an amino group are preferred, with (2-aminoC2-4 alkyl)aminoC2-4 alkyltriC1-4 alkoxysilanes being more preferred, and 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane being even more preferred.

[0112] The silicon-based crosslinking agent is preferably added in an amount of 0.05 to 4.00 wt %, more preferably 0.10 to 3.50 wt %, and even more preferably 0.15 to 3.00 wt % to the composition constituting the coating layer. The addition of a silicon-based crosslinking agent promotes film hardening and improves cohesive strength, resulting in a film with excellent water-resistant adhesion and also expected to prevent oligomer exposure. If the amount added exceeds 4.00 wt %, the film hardens and improves cohesive strength, but some unreacted portions may remain, potentially reducing interlayer adhesion. On the other hand, if the amount added is less than 0.05 wt %, sufficient cohesive strength may not be obtained.

[0113] The polyester resin used in the anchor coat layer (C) of the present invention is produced by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The molecular weight of the polyester resin is not particularly limited as long as it can provide sufficient film toughness, coatability, and solvent solubility for use as a coating material, but the number average molecular weight is preferably 1,000 to 50,000, more preferably 1,500 to 30,000. The functional group at the polyester end is also not particularly limited; it may be an alcohol end, a carboxylic acid end, or both. However, when an isocyanate-based curing agent is used in combination, it is necessary to use a polyester polyol that is predominantly alcohol-terminated.

[0114] The Tg of the polyester resin used in the anchor coat layer (C) of the present invention is preferably 10°C or higher. If the temperature is lower than this, the resin will become tacky after the coating operation, making blocking more likely to occur and making the winding operation after coating more difficult. If the Tg is less than 10°C, it will be difficult to prevent blocking even under conditions where the pressure near the winding core is high, even with the addition of an anti-blocking agent. The Tg is more preferably 15°C or higher, even more preferably 20°C or higher, and preferably 70°C or lower, more preferably 60°C or lower.

[0115] The polyester resin used in the anchor coat layer (C) of the present invention is a polycondensate of a polycarboxylic acid component and a polyhydric alcohol component. The polycarboxylic acid component of the polyester resin used in the present invention includes, for example, at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. Ortho-orientation improves solubility in solvents, enabling uniform coating on the substrate. A uniformly coated film reduces variation in barrier performance, thereby contributing to the suppression of oligomer whitening. Furthermore, ortho-orientation results in a film with excellent flexibility and improved interfacial adhesion, which reduces damage to the substrate due to wet heat treatment and leads to the suppression of oligomers.

[0116] Examples of aromatic polycarboxylic acids or anhydrides thereof in which a carboxylic acid is substituted at the ortho position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracenecarboxylic acid or anhydride. These compounds may have a substituent at any carbon atom of the aromatic ring. Examples of such substituents include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimide group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group. Furthermore, polyester polyols containing these polycarboxylic acids at a content of 70 to 100 mol% relative to 100 mol% of the total polycarboxylic acid components are particularly preferred, as they not only effectively improve barrier properties but also have excellent solvent solubility, which is essential for coating materials.

[0117] In the present invention, other polycarboxylic acid components may be copolymerized within the range that does not impair the effects of the invention. Specifically, examples of aliphatic polycarboxylic acids include succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; examples of unsaturated bond-containing polycarboxylic acids include maleic anhydride, maleic acid, and fumaric acid; examples of alicyclic polycarboxylic acids include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; examples of aromatic polycarboxylic acids include terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, diphenic acid and its anhydride, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, and anhydrides or ester-forming derivatives of these dicarboxylic acids; and ... p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids. These polybasic acids can be used alone or in mixtures of two or more. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalic acid, and diphenic acid are preferred from the viewpoint of organic solvent solubility and gas barrier properties.

[0118] The polyhydric alcohol component of the polyester used in the anchor coat layer (C) of the present invention is not particularly limited as long as it can synthesize a polyester that exhibits gas barrier filling performance, but it is preferable for it to contain a polyhydric alcohol component containing at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, and 1,3-bishydroxyethylbenzene. Among these, it is most preferable to use ethylene glycol as the main component, because it is presumed that the fewer the number of carbon atoms between oxygen atoms, the less flexible the molecular chain becomes and the more difficult oxygen permeates.

[0119] In the present invention, it is preferable to use the polyhydric alcohol component described above, but other polyhydric alcohol components may also be copolymerized within the scope of not impairing the effects of the present invention. Specific examples of diols include 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of trihydric or higher alcohols include glycerol, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl)isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythritol. Polyesters containing glycerol and tris(2-hydroxyethyl)isocyanurate in combination are particularly preferred, as they have a moderately high crosslinking density due to their branched structure, resulting in good solubility in organic solvents and excellent barrier function.

[0120] Examples of catalysts that can be used in the reaction to obtain the polyester of the present invention include tin-based catalysts such as monobutyltin oxide and dibutyltin oxide, titanium-based catalysts such as tetraisopropyltitanate and tetrabutyltitanate, and acid catalysts such as zirconia-based catalysts such as tetrabutylzirconate. It is preferable to use a combination of the above-mentioned titanium-based catalysts, such as tetraisopropyltitanate and tetrabutyltitanate, which have high activity in esterification reactions, with the above-mentioned zirconia catalyst. The amount of the catalyst is preferably 1 to 1,000 ppm, more preferably 10 to 100 ppm, based on the total mass of the reaction raw materials used. If the amount is less than 1 ppm, it is difficult to obtain the catalytic effect, and if it exceeds 1,000 ppm, problems such as inhibition of the urethanization reaction may occur when an isocyanate curing agent is used.

[0121] In the present invention, when a polyester resin is used as the main component of the coating agent constituting the anchor coat layer (C), it is particularly preferable to use an isocyanate-based curing agent to form a urethane resin. In this case, the coating layer becomes crosslinked, which has the advantage of improving heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use in boiled or retort packaging. On the other hand, there are problems with the liquid not being reusable after mixing with the curing agent, and a curing (aging) process is required after coating. Examples of advantages include the fact that, as a simple overcoat varnish, there is no risk of thickening of the coating liquid, coating production is easy to manage, the coating liquid can be diluted and reused, and a curing process (so-called aging process) is not required. In this case, the polyester used can be terminated with a polyol, a polycarboxylic acid, or a mixture of these without any problems. On the other hand, the resin of the coating layer is linear, which may result in insufficient heat resistance or abrasion resistance, or problems with use in boiled or retort packaging.

[0122] When a curing agent is used in the coating layer, since it is a coating on a film, an isocyanate-based curing agent is preferred from the perspective of the film's heat resistance. In this case, the resin component of the coating material must be polyester polyol. On the other hand, when an epoxy-based compound is used as the curing agent, a polyester polycarboxylic acid is required. In these cases, the coating layer becomes crosslinked, which has the advantage of improving heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use in boiled and retort packaging. However, there are problems with this method, such as the liquid not being reusable after mixing with the curing agent, and the need for a curing (aging) process after application.

[0123] When the polyester has hydroxyl groups, the polyisocyanate compound used in the present invention reacts at least partially to form a urethane structure, thereby making the resin component highly polar and causing aggregation between polymer chains, thereby further strengthening the gas barrier function. Furthermore, when the resin of the coating material is a linear resin, crosslinking with a trivalent or higher polyisocyanate can impart heat resistance and abrasion resistance. The polyisocyanate compound used in the present invention may be a diisocyanate, a trivalent or higher polyisocyanate, a low-molecular-weight compound, or a high-molecular-weight compound, but it is preferable to contain an aromatic ring or an aliphatic ring as part of the skeleton from the viewpoint of improving the gas barrier function. Examples of isocyanates having an aromatic ring include toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; examples of isocyanates having an aliphatic ring include hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, isophorone diisocyanate, and norbornane diisocyanate, as well as trimers of these isocyanate compounds, and compounds containing terminal isocyanate groups obtained by reacting an excess amount of these isocyanate compounds with low-molecular-weight active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine, or high-molecular-weight active hydrogen compounds such as various polyester polyols, polyether polyols, and polyamides. The polyisocyanate compound may be an adduct, allophanate, or biuret. Among these, it is preferable to use a trimethylolpropane adduct of metaxylylene diisocyanate as the polyisocyanate compound.

[0124] The method for forming the anchor coat layer (C) is not particularly limited, and conventionally known methods such as coating methods can be used. Among coating methods, offline coating and in-line coating methods are preferred. For example, in the case of in-line coating, which is performed in the film production process, the conditions for drying and heat treatment during coating depend on the coat thickness and the equipment conditions, but it is preferable to feed the film to a stretching process in the perpendicular direction immediately after coating and dry it in the preheating zone or stretching zone of the stretching process. In such cases, it is usually preferable to use a temperature of about 50 to 250°C.

[0125] The method for applying the resin composition for the anchor coat layer (C) is not particularly limited as long as it is a method that can apply the resin composition to the film surface to form a layer, and for example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0126] When forming the anchor coat layer (C), it is preferable to heat-dry the resin composition for the anchor coat layer after coating, with the drying temperature being preferably 100 to 145°C, more preferably 110 to 140°C, and even more preferably 110 to 130°C. If the drying temperature is below 100°C, the anchor coat layer may not be sufficiently dried. On the other hand, if the drying temperature exceeds 145°C, the film may be overheated, becoming brittle or shrinking, resulting in poor processability. In particular, it is particularly preferable to first volatilize the solvent at a relatively low temperature of 80 to 110°C immediately after coating, and then dry at 120°C or higher, as this will result in a uniform film. In addition to drying, additional heat treatment at as low a temperature as possible is also effective in promoting the formation of the anchor coat layer.

[0127] [Protective Layer (D)] In the present invention, a protective layer may be laminated on the gas barrier layer, and it is preferable to have a protective layer (D) on the inorganic thin film layer that is the gas barrier layer. An inorganic thin film layer made of a metal or metal oxide layer is not a completely dense film, but has minute defects scattered therein. By forming a protective layer by applying a specific resin composition for a protective layer (described below) on a metal oxide layer, the resin in the resin composition for a protective layer penetrates into the defects in the metal oxide layer, resulting in the effect of stabilizing the barrier properties of the gas barrier layer. In addition, using a material with gas barrier properties for the protective layer itself also improves the gas barrier performance of the laminate film.

[0128] The resin composition used for the protective layer (D) of the present invention can be a polyvinyl alcohol-based, urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resin, or the like, and a curing agent such as an epoxy-based, isocyanate-based, melamine-based, or silanol-based curing agent can be added. It can also contain a crosslinking agent such as a silicon-based crosslinking agent, an oxazoline compound, a carbodiimide compound, or an epoxy compound. In particular, the protective layer is preferably composed of a composition containing a polyvinyl alcohol-based resin and a silicon-based crosslinking agent. Examples of the polyvinyl alcohol-based resin and the silicon-based crosslinking agent include those similar to those described above.

[0129] In the present invention, the amount of the protective layer (D) is 0.10 to 0.40 (g / m 2 ) is preferable. This allows the protective layer to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. In addition, the cohesive force of the protective layer (D) itself is improved, and the adhesion between the inorganic thin film layer and the protective layer is also strengthened. The amount of the protective layer to be applied is more preferably 0.13 (g / m 2 ) or more, more preferably 0.16 (g / m 2 ) or more, and even more preferably 0.19 (g / m 2 ) or more, and preferably 0.37 (g / m 2 ) or less, more preferably 0.34 (g / m 2 ) or less, more preferably 0.31 (g / m 2The amount of the protective layer (D) deposited is 0.40 (g / m 2 ), the gas barrier properties are improved, but the cohesive force inside the protective layer becomes insufficient and the uniformity of the protective layer also decreases, which may result in unevenness or defects in the coat appearance and insufficient gas barrier properties and adhesiveness. On the other hand, when the coating amount of the protective layer (D) exceeds 0.10 (g / m), 2 If the thickness is less than 1 / 2 mm, sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0130] The method for applying the resin composition for the protective layer is not particularly limited as long as it is a method that can apply the resin composition for the protective layer to the surface of a film to form a layer. For example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0131] When forming the protective layer (D), it is preferable to apply the protective layer resin composition and then heat-dry it. The drying temperature is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C. Drying temperatures below 100°C can result in insufficient drying of the protective layer, or the formation of the protective layer cannot proceed, resulting in reduced cohesive strength and water-resistant adhesion, and consequently reduced barrier properties and hand-tearability. On the other hand, drying temperatures above 160°C can result in excessive heat being applied to the film, making it brittle and reducing puncture strength, or shrinking and reducing processability. It is particularly preferable to first volatilize the solvent at a relatively low temperature of 90 to 110°C immediately after application, and then dry the protective layer at 130°C or higher, as this results in a uniform and transparent film. In addition to drying, additional heat treatment at as low a temperature as possible can also be more effective in promoting the formation of the protective layer.

[0132] [Other Films] In the present invention, other films may be laminated to a stretched laminated polyolefin resin film containing a polyolefin resin as a main component, as long as the monomaterial ratio relative to the packaging material, as described below, is satisfied. The other films used in the present invention are, for example, films obtained by melt-extruding a plastic and, as necessary, stretching it in the longitudinal direction and / or the width direction, cooling, and heat setting. Examples of plastics include polyamides such as nylon 4.6, nylon 6, nylon 6.6, and nylon 12, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, as well as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, polystyrene, and polylactic acid.

[0133] The other films in the present invention can be of any thickness depending on the desired purpose, such as mechanical strength and transparency. The thickness of the other films is not particularly limited, but is usually recommended to be 5 to 250 μm, and when used as a packaging material, it is desirable to be 10 to 60 μm. However, it is necessary to take into consideration the mono-material ratio of the packaging material, which will be described later.

[0134] The other film in the present invention may be a laminated film of one or more types of plastic films. When a laminated film is used, the type of laminate, the number of layers, the lamination method, etc. are not particularly limited, and can be arbitrarily selected from known methods depending on the purpose.

[0135] [Adhesive Layer] In the present invention, a barrier adhesive layer is preferably laminated on the gas barrier layer. The adhesive layer used in the present invention can be a general-purpose laminating adhesive. For example, solvent-free, aqueous, or hot-melt adhesives based on poly(ester)urethane, polyester, polyamide, polyamine, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, casein, or the like can be used. Among these, adhesives obtained by crosslinking polyurethane, polyester, or polyamine resins are preferred from the viewpoints of heat resistance, flexibility capable of adapting to dimensional changes in each substrate, and improved gas barrier properties of the adhesive itself. However, caution is required because if the film becomes too hard due to crosslinking, there is a risk of reduced barrier performance after bending. It is also effective to add inorganic substances such as particles to improve barrier performance. The adhesive layer can be applied by, for example, direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fountain coating, or other methods. To achieve sufficient adhesiveness, the thickness after drying is preferably 1 to 8 μm, more preferably 2 to 7 μm, and even more preferably 3 to 6 μm. If the coating weight is less than 1 μm, it becomes difficult to bond the entire surface, and adhesive strength decreases. Furthermore, if the coating weight exceeds 8 μm, it takes a long time for the film to completely cure, unreacted material is likely to remain, and adhesive strength decreases.

[0136] [Printed Layer] Furthermore, in the packaging material of the present invention, at least one printed layer may be laminated between the stretched laminated polyolefin resin film and the film to be laminated or on the outside thereof.

[0137] As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks are preferably used. Examples of resins used in printing inks include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printing layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. To dry the solvent after printing, known drying methods such as hot air drying, heat roll drying, and infrared drying can be used.

[0138] [Characteristics of Stretched Laminated Polyolefin Resin Film] The stretched laminated polyolefin resin film of the present invention can have any laminate structure as a packaging material. From the viewpoint of environmental impact, using the laminated film alone is preferable because it minimizes the number of materials used and the number of lamination steps. On the other hand, from the viewpoint of further improving barrier properties, printability, toughness, and stiffness, a laminate laminated with, for example, another substrate film is also one preferred structure. In this case, by laminating a printing layer on the front substrate film, there is also the advantage that it is not necessary to print on a film having a gas barrier layer. Other suitable structures include laminating the film with a white substrate film to improve concealment properties, or with an ultraviolet-blocking film to provide light-blocking properties.

[0139] From the viewpoint of toughness, the stretched laminated polyolefin resin film of the present invention must have a puncture strength of 10 N or more as measured in accordance with JIS Z1707. This range ensures the film's toughness and allows it to be used as a packaging material that is resistant to punctures. The puncture strength is preferably 11 N or more, more preferably 12 N or more, and preferably 20 N or less or 19 N or less. If the puncture strength is less than 10 N, the toughness is insufficient, and when used as a bag, an external load may cause a puncture, resulting in leakage of the contents. Furthermore, from the perspective of reducing the volume of plastic film, it is preferable that a thinner film can exhibit the above-mentioned puncture strength and the seal strength described below. In particular, in processes such as vapor deposition, which have limitations on the winding diameter that can be input per batch, a thinner film thickness increases the amount that can be processed per batch, and therefore, improved productivity can be expected. In this sense, the preferred thickness range of the stretched laminated polyolefin resin film is 45 μm or less, more preferably 40 μm or less, and even more preferably 35 μm or less.

[0140] The stretched laminated polyolefin resin film of the present invention must have a Young's modulus in both the MD and TD directions of 1 GPa or more. This range results in a packaging material with excellent stiffness, self-standing ability, and ease of handling. The Young's modulus in both the MD and TD directions is preferably 1.2 GPa or more, more preferably 1.4 GPa or more, and preferably 5 GPa or less, more preferably 4 GPa or less, and even more preferably 3.5 GPa or less. If the Young's modulus is less than 1 GPa, the stiffness may be insufficient, resulting in problems with the self-standing ability and handling of the bag.

[0141] The stretched laminated polyolefin resin film of the present invention must have a seal strength of 8 N / 15 mm or more when the heat-sealable layers are heat-sealed together at 150°C, 0.2 MPa, and for 2 seconds. If the seal strength is less than 8 N / 15 mm, the sealed portion tends to peel off, limiting its use as a packaging bag, such as preventing it from being used for applications with large contents. The heat seal strength is preferably 9 N / 15 mm or more, more preferably 10 N / 15 mm or more, and preferably 20 N / 15 mm or less, more preferably 19 N / 15 mm or less, and even more preferably 18 N / 15 mm or less. The heat seal strength can be measured, for example, in accordance with JIS Z1707.

[0142] In the present invention, the heat shrinkage rate of the stretched laminated polyolefin resin film at 120°C for 15 minutes must be 10% or less in both the MD and TD directions. This ensures the heat resistance required for processing the film and for use as a packaging material. For example, even when the film is subjected to thermal load during coating, vapor deposition, printing, or lamination, dimensional change is minimal, preventing deterioration of barrier performance in terms of quality and wrinkles and sagging in terms of quality. Furthermore, the film achieves good finish when heat-sealed at high temperatures of 120°C or higher to form a packaging material, ensuring stable seal strength. Furthermore, the film exhibits minimal dimensional and appearance changes even when subjected to severe moist heat treatment, resulting in a high-quality packaging material. The heat shrinkage rate at 120°C for 15 minutes is preferably 9.5% or less, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, preferably 0.1% or more, more preferably 0.5% or more, and even more preferably 1.0% or more. A heat shrinkage rate of more than 10% may result in deterioration of barrier properties during processing. Furthermore, heat wrinkles and sagging may occur, which may result in a decrease in quality.

[0143] The stretched laminated polyolefin resin film of the present invention has an oxygen permeability of 1000 ml / m under conditions of 23°C x 65% RH when used alone. 2It is preferable that the oxygen permeability is 900 ml / m or less in terms of exhibiting good gas barrier properties. Within this range, a certain level of barrier performance can be expected compared to olefin films even when used alone, and even higher barrier performance can be exhibited by laminating with other films. The oxygen permeability is more preferably 900 ml / m or less. 2 d MPa or less, more preferably 800 ml / m 2 d MPa or less, even more preferably 750 ml / m 2 d MPa or less, preferably 1 ml / m 2 d MPa or more, more preferably 5 ml / m 2 d MPa or more, more preferably 10 ml / m 2 ・d・MPa or more. Oxygen permeability is 1000 ml / m 2 If the pressure exceeds .d.MPa, it becomes difficult to use the film in applications where gas barrier properties are required. The oxygen permeability can be measured, for example, in accordance with JIS-K7126 Method B.

[0144] The stretched laminated polyolefin resin film of the present invention preferably has an oxygen permeability of 60 ml / m under conditions of 23°C x 65% RH when bonded to another film via an adhesive. 2 It is preferable that the oxygen permeability is 50 ml / m or less, since good gas barrier properties are exhibited. 2 d MPa or less, more preferably 40 ml / m 2 d MPa or less, preferably 0.5 ml / m 2 d MPa or more, more preferably 1 ml / m 2 ・d・MPa or more. Oxygen permeability is 60 ml / m 2 If the pressure exceeds 0.5 d MPa, it becomes difficult to use the film in applications that require high gas barrier properties. 2 If the viscosity is less than d·MPa, the barrier performance will be excellent, but the residual solvent will be less likely to permeate to the outside of the bag, which is undesirable as there is a risk that the amount of solvent that migrates to the contents will increase relatively.

[0145] The stretched laminated polyolefin resin film of the present invention has a water vapor permeability of 3.0 g / m under conditions of 40°C x 90% RH when used alone. 2 The water vapor permeability is preferably 2.5 g / m or less in order to exhibit good gas barrier properties. 2 d or less, more preferably 2.0 g / m 2 d or less, preferably 0.1 g / m 2 d or more, more preferably 0.2 g / m 2 The water vapor permeability can be 3.0 g / m or more. 2 If the value exceeds d, it becomes difficult to use the film in applications that require high gas barrier properties. The water vapor permeability can be measured, for example, in accordance with JIS-K7129 Method B.

[0146] As a criterion for evaluating the mono-material nature of packaging materials made using the stretched laminated polyolefin resin film of the present invention, when the ratio of the thickness of the polyolefin material to the total thickness of each film and adhesive is calculated as the mono-material (mono-material) ratio, the mono-material ratio is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and even more preferably 95% or more. By keeping the mono-material ratio within this range, a packaging material configuration that is easy to recycle can be achieved. If the mono-material ratio is less than 70%, recycling may be difficult due to foreign matter from other materials. Note that if all the polyolefin materials used are polypropylene resins, a configuration that is even easier to recycle can be achieved.

[0147] In packaging materials made using the stretched laminated polyolefin resin film of the present invention, the total thickness of the films and adhesive is preferably 20 to 140 μm, more preferably 25 to 135 μm, and even more preferably 30 to 130 μm. By keeping the total thickness of the packaging material within this range, a package can be obtained that exhibits the necessary physical properties, such as the firmness required for the packaging material, as well as the toughness and barrier performance, as described above. If the total thickness is less than 20 μm, the bag will not have enough firmness and will not stand on its own. Furthermore, the bag will not have enough toughness, and there is a risk of tearing or holes. On the other hand, if the total thickness exceeds 140 μm, the bag will be too stiff, making it difficult to handle, and will also increase the cost of the package, which is economically undesirable.

[0148] As described above, packaging materials made using the stretched laminated polyolefin resin film of the present invention have excellent heat-sealing properties, stiffness, toughness, heat resistance, and barrier properties, and can be used as various packages. Examples of packages include those for general food, frozen food, vacuum packaging, boiled retort food, and microwave heating. In particular, the laminated polyolefin resin film of the present invention is preferably used for microwave heating.

[0149] The shape of the packaging material made of the stretched laminated polyolefin resin film of the present invention is not particularly limited and can take various shapes, such as three-sided or four-sided pouches, standing pouches, spout pouches, etc.

[0150] The present invention also encompasses a package in which an item to be packaged is packaged in a packaging material. The contents filled in a packaging bag using the packaging material of the present invention are not particularly limited, and may be liquid, powder, or gel. The contents may also be food or non-food.

[0151] This application claims the benefit of priority based on Japanese Patent Application No. 2023-072695, filed on April 26, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-072695, filed on April 26, 2023, are incorporated herein by reference.

[0152] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Various evaluations were carried out by the following measurement methods. In the examples, the stretched laminated polyolefin resin film will hereinafter be referred to as a laminated film.

[0153] (1) Thickness of Various Films The thickness was measured using a dial gauge in accordance with JIS K7130-1999 Method A.

[0154] (2) Composition and Thickness of Inorganic Thin Film (B) on Laminate Film The laminate films (after lamination) obtained in Examples and Comparative Examples were measured for thickness composition using a fluorescent X-ray analyzer (Rigaku Corporation, "Supermini 200") based on a pre-prepared calibration curve. The excitation X-ray tube conditions were 50 kV and 4.0 mA.

[0155] (3) Amount of adhesion of coating layer (A), anchor coat layer (C), and protective layer (D) on laminate film In each example and comparative example, each laminate film obtained at the stage where a predetermined coating layer (A), anchor coat layer (C), and protective layer (D) were laminated on the laminate film was used as a sample, and a test piece of 100 mm x 100 mm was cut out from this sample, and the coating layer was wiped off with either water, ethanol, or acetone, and the amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0156] (4) Method for Evaluating Heat-Seal Strength of Laminated Films The heat-seal strength of the laminated films obtained in the Examples and Comparative Examples was measured in accordance with JIS Z1707. The specific procedure is as follows: The heat-sealable layers of the films were bonded together using a heat sealer. The heat-sealing conditions were an upper bar temperature of 150°C, a lower bar temperature of 30°C, a pressure of 0.2 MPa, and a time of 2 seconds. Adhesive samples were cut out to a seal width of 15 mm. Peel strength was measured at a tensile speed of 200 mm / min using a universal tensile tester "DSS-100" (Shimadzu Corporation). The heat-seal strength was expressed as the strength per 15 mm (N / 15 mm). The seal appearance was evaluated relative to the other: ◯ for a wrinkle-free seal, △ for partial wrinkles, and × for wrinkles covering the entire surface.

[0157] (5) Puncture Strength of Laminated Film The films obtained in the Examples and Comparative Examples were sampled into 5 cm squares, and the puncture strength of the films was measured in accordance with JIS Z1707 using a digital force gauge "ZTS-500N," an electric test stand "MX2-500N," and a puncture jig "TKS-250N," all manufactured by Imada Co., Ltd. The unit of measurement was N.

[0158] (6) Evaluation of Heat Shrinkage of Laminated Films Test pieces 20 mm wide and 300 mm long were prepared for each laminated film produced in each Example and Comparative Example, with the measurement direction (MD or TD) being the long side. A gauge mark was placed 200 mm apart in the center of the test piece. The distance between the gauge marks was then measured to the first decimal place with a metal ruler, and the gauge mark distance A before heating was determined. The test piece was then clamped at its ends with clips, hung from a metal bar, and placed in a heating oven controlled at 120°C ± 1°C for 15 minutes. After heating, the gauge mark distance of the removed test piece was measured with a metal ruler in the same manner as before heating, and the gauge mark distance B after heating was determined. The heat shrinkage was calculated using the calculated values ​​using the following formula: Heat shrinkage (%) = (A - B) / A x 100

[0159] (7) Evaluation of Young's modulus of laminated film The Young's modulus in the longitudinal and transverse directions of the film was measured at 23°C in accordance with JIS K 7127. Samples of 15 mm x 200 mm were cut out of the film and set in a tensile tester (Instron 5965, a dual-column tabletop tester manufactured by Instron Japan Co., Ltd.) with a chuck width of 100 mm. A tensile test was carried out at a tensile speed of 200 mm / min. The Young's modulus was determined from the slope of the linear portion of the obtained strain-stress curve at the initial stage of elongation.

[0160] (8) Evaluation method for oxygen transmission rate (OTR) of laminated film The oxygen transmission rate of the films obtained in the examples and comparative examples was measured in accordance with JIS-K7126 Method B using an oxygen transmission rate measuring device (OX-TRAN (registered trademark) 2 / 22 manufactured by MOCON Co., Ltd.) under an atmosphere of a temperature of 23°C and a humidity of 65% RH. The measurement of the oxygen transmission rate was carried out in the direction in which oxygen permeates from the substrate film side to the heat-sealable layer side.

[0161] (9) Evaluation method for water vapor transmission rate (WVTR) of laminated film The water vapor transmission rate of the films obtained in the examples and comparative examples was measured in accordance with JIS-K7129 Method B using a water vapor transmission rate measuring device ("PERMATRAN-W 3 / 33MG" manufactured by MOCON Co., Ltd.) under an atmosphere of a temperature of 40°C and a humidity of 90% RH. The water vapor transmission rate was measured in the direction in which water vapor permeated from the substrate film side to the heat-sealable layer side.

[0162] [Preparation of Packaging Materials] (10) Preparation of Evaluation Packaging Materials The surface of each of the following films was coated with adhesive 1 or 2 to a thickness of 3.5 μm after drying at 80° C. The substrate layer side of the laminated film obtained in the Examples and Comparative Examples was dry-laminated on a metal roll heated to 60° C., and aged at 40° C. for 4 days (96 hours) to obtain a laminate for evaluation. One of the following two types of adhesive was used. Adhesive 1: Main component C: polyester / curing agent C: isocyanate-curing adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) Adhesive 2: Main component A: polyamine / curing agent A: epoxy-curing adhesive (C93 / M100 manufactured by Mitsubishi Gas Chemical Company, Inc.)

[0163] (11) Evaluation method for oxygen transmission rate (OTR) of packaging material The oxygen transmission rate of the packaging material prepared in (10) above was measured in accordance with JIS-K7126 Method B using an oxygen transmission rate measuring device (OX-TRAN (registered trademark) 2 / 22 manufactured by MOCON Corporation) under an atmosphere of a temperature of 23°C and a humidity of 65% RH. The measurement of the oxygen transmission rate was carried out in the direction in which oxygen permeates from the base film side of the packaging material to the heat-sealable layer side.

[0164] (12) Evaluation Criteria for Mono-Materialization: Mono-Material Ratio For the packaging materials prepared in (10) above, the ratio of the thickness of the olefin-based material to the total thickness of each film and adhesive was calculated as the mono-material ratio as an evaluation criterion for mono-materialization.

[0165] The propylene homopolymers or propylene copolymers used in the present examples and comparative examples are listed below. The propylene homopolymers or propylene copolymers used in Examples 1 to 12 and Comparative Examples 1 to 6 are shown in Tables 1 and 2A.

[0166] The resins constituting each layer used in the following production examples are as follows: PP-A: Propylene homopolymer: "FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd., MFR: 2.5 g / 10 min, melting point: 158°C PP-B: Propylene-ethylene-butene random copolymer: "FSX66E8" manufactured by Sumitomo Chemical Co., Ltd., ethylene content: 2.5 mol%, butene content: 7 mol%, MFR: 3.1 g / 10 min, melting point: 133°C PP-C: Ethylene-butene copolymer: "A-4085S" manufactured by Mitsui Chemicals, Inc., MFR: 6.7 g / 10 min, melting point: 66°C PP-D: Propylene-butene copolymer: "SP8931" manufactured by Sumitomo Chemical Co., Ltd., butene content: 33 mol%, MFR: 9.0 g / 10 min, melting point: 130°C

[0167] [Manufacturing Example 1] Using three melt extruders, a base layer (PP-A: 100 parts by weight) was extruded from the first extruder, an intermediate layer (PP-B: 100 parts by weight) was extruded from the second extruder, and a heat-sealing layer (a mixed resin of PP-B: 30 parts by weight and PP-D: 70 parts by weight) was extruded from the third extruder. Each was melt-extruded at a resin temperature of 260 ° C., and laminated in a T-die to form a base layer / intermediate layer / heat-sealing layer. This was then cooled and solidified with a chill roll at 20 ° C. The resulting unstretched film was then stretched 4.5 times in the machine direction at 125 ° C., then stretched 8 times in the transverse direction at 163 ° C., and heat-set at 169 ° C. while relaxing by 6.7% in the width direction (TD). A laminated film OPP1 (30 μm) was obtained, with a base layer of 21.5 μm, an intermediate layer of 7.5 μm, and a heat-sealing layer of 1 μm. The surface of the base layer of this biaxially oriented polypropylene film was subjected to corona treatment using a corona treater manufactured by Softal Corona & Plasma GmbH at an applied current of 0.75 A, and then the film was wound up on a winder. Table 1 shows the structure of the laminated film OPP1.

[0168] [Production Examples 2 to 7] Laminated films OPP2 to OPP7 were produced in the same manner as in Production Example 1, except that the blending ratio of the resins constituting each layer of the laminated film and the thickness of each layer were changed as shown in Table 1. The compositions of OPP2 to OPP7 are shown in Table 1.

[0169] (Other base films) (OPP-A) Biaxially oriented polypropylene film (P2102-30 μm, manufactured by Toyobo Co., Ltd.) (CPP) Non-oriented polypropylene film (P1128-30 μm, manufactured by Toyobo Co., Ltd.)

[0170] (Coating Layer (A)) Details of the coating liquid for forming the coating layer (A) used in the present examples and comparative examples are described below. The coating layers used in Examples 1 and 2 are shown in Table 2A.

[0171] [Polyvinyl alcohol resin (a)] To 90 parts by weight of purified water, 10 parts by weight of a fully saponified polyvinyl alcohol resin (trade name: G Polymer OKS8049Q (saponification degree 99.0% or more, average polymerization degree 450), manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added, and the mixture was heated to 80°C with stirring, and then stirred for about 1 hour. The mixture was then cooled to room temperature, thereby obtaining a nearly transparent polyvinyl alcohol solution (PVA solution) with a solids content of 10%.

[0172] [Inorganic layered compound dispersion (b)] 5 parts by weight of montmorillonite (trade name: Kunipia F, manufactured by Kunimine Industries Co., Ltd.), an inorganic layered compound, was added to 95 parts by weight of purified water with stirring, and the mixture was thoroughly dispersed using a homogenizer at a setting of 1500 rpm. Thereafter, the mixture was kept at 23°C for 1 day to obtain an inorganic layered compound dispersion with a solid content of 5%.

[0173] [Coating Liquid 1 Used for Coating Layer 1] A coating liquid (resin composition for coating layer) was prepared by mixing the materials in the following blending ratio: Ion-exchanged water 15.00% by weight, Isopropyl alcohol 15.00% by weight, Polyvinyl alcohol resin (a) 30.00% by weight, Inorganic layer compound dispersion (b) 40.00% by weight

[0174] [Coating of Coating Solution 1 on a Film (Lamination of Coating Layer 1)] The above-prepared Coating Solution 1 was applied to the corona-treated surface of a substrate film by gravure roll coating, pre-dried at 90°C for 4 seconds, and then fully dried at 120°C for 4 seconds to obtain a coating layer. The coating layer adhesion amount at this time was 0.30 g / m 2 Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminated film provided with a coating layer 1 was produced.

[0175] [Preparation of Coating Liquid 2 Used for Coating Layer 2] A solution obtained by hydrolyzing tetraethoxysilane with 0.02 mol / L hydrochloric acid was added to a 5 wt % aqueous solution of polyvinyl alcohol resin (PVA) having a saponification degree of 99% and a polymerization degree of 2400 in a weight ratio of SiO / PVA = 40 / 60 to prepare Coating Liquid 2.

[0176] [Coating of Coating Solution 2 on Film (Lamination of Coating Layer 2)] The above-prepared Coating Solution 2 was applied to the corona-treated surface of the substrate film by gravure roll coating, pre-dried at 90°C for 4 seconds, and then fully dried at 120°C for 4 seconds to obtain a coating layer. The coating layer adhesion amount at this time was 1.00 g / m 2 Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminated film provided with a coating layer 2 was produced.

[0177] (Inorganic Thin Film Layer (C)) The method for producing the inorganic thin film layer (C) used in each example and comparative example is described below. The inorganic thin film layers used in examples 3 to 12 and comparative examples 2 to 6 are shown in Table 2A. (In the table, the inorganic thin film layer is referred to as the inorganic layer.)

[0178] (Formation of Inorganic Thin Film Layer 1 (Vapor Deposition 1)) Metallic aluminum was vapor-deposited on the substrate layer or the anchor coat layer to form the inorganic thin film layer 1. A small vacuum vapor deposition apparatus (VWR-400 / ERH, manufactured by ULVAC KIKO Co., Ltd.) was used for 10 minutes. -3 After reducing the pressure to below 100 Pa, aluminum foil with a purity of 99.9% was placed in a Nilaco evaporation source CF-305W from below the substrate, and metallic aluminum was heated and evaporated to form a metallic aluminum film with a thickness of 70 nm on the film.

[0179] (Formation of Inorganic Thin Film Layer 2 (Vapor Deposition 2)) Silicon oxide was vapor-deposited onto the substrate layer or the anchor coat layer to form the inorganic thin film layer 2. A small vacuum vapor deposition apparatus (VWR-400 / ERH, manufactured by ULVAC KIKO Co., Ltd.) was used for 10 minutes. -3 After reducing the pressure to below 1 Pa, silicon oxide was placed in a Nilaco evaporation source B-110 from below the substrate and evaporated by heating to form a silicon oxide film with a thickness of 40 nm on the film.

[0180] (Formation of inorganic thin film layer 3 (vapor deposition 3)) As the inorganic thin film layer 3, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the substrate layer or anchor coat layer by electron beam vapor deposition. As the vapor deposition source, granular SiO2 (purity 99.9%) and Al2O3 (purity 99.9%) of about 3 mm to 5 mm were used. The inorganic thin film layer (SiO ２ / Al ２ O ３ The composite oxide layer had a thickness of 20 nm. ２ / Al ２ O ３ The weight ratio was 70 / 30.

[0181] (Anchor Coat Layer (B)) The following describes the method for producing the anchor coat layer (B) used in each of Examples 8 and 9. [Polyester Resin (a)] As the polyester component, polyester polyol (DF-COAT GEC-004C manufactured by DIC Corporation: solid content 30%) was used.

[0182] [Polyisocyanate Crosslinking Agent (b)] As the polyisocyanate component, a trimethylolpropane adduct of metaxylylene diisocyanate ("Takenate D-110N" manufactured by Mitsui Chemicals, Inc.: solid content 75%) was used.

[0183] [Silane Coupling Agent (c)] As the silane coupling agent, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane ("KBM-603" manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

[0184] [Coating Solution 1 for Anchor Coat Layer 1 (AC1)] A solution (15% by weight) of silane coupling agent (c) dissolved in acetone and polyisocyanate crosslinking agent (b) were mixed in the following ratio and stirred for 10 minutes using a magnetic stirrer. The resulting mixture was diluted with methyl ethyl ketone and 1-methoxy-2-propanol (hereinafter referred to as PGM), and polyester resin (a) was then added to obtain the target coating solution 1. The mixing ratio is shown below: Polyester resin (a) 10.62% by weight Polyisocyanate crosslinking agent (b) 4.07% by weight Silane coupling agent (c) *acetone diluted solution 1.73% by weight Methyl ethyl ketone 69.55% by weight PGM 14.03% by weight

[0185] (Coating of coating liquid onto film (lamination of anchor coat layer)) Coating liquid 1 was used for the coating layer, and applied to the corona-treated surface of the substrate film by gravure roll coating. After pre-drying at 95°C for 4 seconds, the coating was dried at 115°C for 4 seconds to obtain an anchor coat layer. The adhesion amount of the anchor coat layer at this time was 0.40 g / m 2 Thereafter, a post-heat treatment was carried out at 40° C. for 4 days (96 hours) to obtain the desired laminated film.

[0186] (Protective Layer (D)) The method for producing the protective layer (D) used in Example 9 will be described below.

[0187] [Coating Solution 1 used for Protective Layer (D)] A solution obtained by hydrolyzing tetraethoxysilane with 0.02 mol / L hydrochloric acid was added to a 5 wt % aqueous solution of polyvinyl alcohol resin (PVA) having a saponification degree of 99% and a polymerization degree of 2400, in a weight ratio of SiO / PVA = 60 / 40, to prepare a gas barrier protective layer solution (Coating Solution 1).

[0188] (Coating of Coating Liquid on Film (Lamination of Protective Layer)) The above-mentioned Coating Liquid 1 was applied onto the inorganic thin film layer of the laminated film by gravure roll coating, and dried in a dry oven at 120°C for 10 seconds to obtain a protective layer (Protection 1). The adhesion amount of the protective layer at this time was 0.30 g / m 2Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminated film provided with a protective layer was produced.

[0189] In this manner, laminated polyolefin films having a coating layer, an anchor coat layer, an inorganic thin film layer, or a protective layer on each laminated film were prepared.

[0190] In each example and comparative example, each film was used alone or in combination with the aforementioned adhesive by dry lamination to prepare packaging materials having the configurations shown in Table 2C. Various evaluations were also carried out on the resulting packages. The results are shown in Table 2B.

[0191]

[0192]

[0193]

[0194]

[0195] According to the present invention, by laminating a predetermined gas barrier layer onto a stretched polyolefin film having a low-melting-point resin layer to form a laminate film, it is possible to significantly improve gas barrier performance and ensure high heat-sealability, heat resistance, stiffness, and toughness, thereby providing an environmentally friendly and highly convenient packaging material. Moreover, since the packaging material of the present invention can be easily produced with few processing steps, it is excellent in both economy and production stability, and can provide packages with uniform properties.