Packaging materials

Abstract

To provide a packaging material that can be formed from resin species with low environmental impact, and that possesses the necessary performance characteristics required for packaging materials, such as gas barrier properties, heat sealability, and processability. [Solution] A packaging material comprising at least one laminated base film, which is a stretched film mainly composed of polyolefin resin, with a gas barrier layer laminated onto it, and a heat-sealable polyolefin resin layer, wherein the gas barrier layer is an inorganic thin film layer, and the laminated base film obtained by peeling the heat-sealable polyolefin resin layer from the packaging material has a heating elongation of 6% or less in both the MD and TD directions, measured at 130°C in a measurement temperature range of 30°C to 150°C with a sample width of 4 mm, a tensile load of 0.39 N, and a heating rate of 20°C / min using a thermomechanical analyzer, and the oxygen permeability of the packaging material in a 23°C × 65% RH environment is 60 ml / m². 2 Packaging material characterized by having a pressure of d·MPa or less.

Description

[Technical Field]

[0001] This invention relates to laminated packaging materials used in the packaging of food, pharmaceuticals, industrial products, and the like. More specifically, it relates to an environmentally friendly laminated packaging material that is excellent in gas barrier properties, processability, toughness, and convenience. [Background technology]

[0002] In recent years, regulations aimed at reducing the use of single-use plastics have been strengthened in Europe and around the world. This is due to a growing international awareness of resource recycling and the worsening waste problem in emerging countries. As a result, there is a demand for environmentally friendly products from the perspective of the 3Rs (recycle, reuse, reduce) for plastic packaging materials used for food, pharmaceuticals, and other products.

[0003] As one possibility for creating environmentally friendly packaging materials, as mentioned above, the idea of ​​using monomaterials—that is, packaging materials made from the same recyclable material—is being actively explored. For example, polyester-based and polyolefin-based materials are being investigated for use in monomaterialization.

[0004] While there is a demand for environmentally friendly packaging materials as described above, the properties required of packaging materials themselves are becoming increasingly multifunctional for convenience. For example, a pouch that can be used in a microwave oven without using aluminum foil requires gas barrier properties, heat resistance, toughness (resistance to tearing and pinholes), and high sealing performance all in one packaging bag. To achieve this, it is necessary to laminate different materials, each with a different function, and a common configuration is at least three layers, with a vapor-deposited polyester film on the outside, a polyamide film in the middle layer, and a polyolefin-based heat-sealable resin on the inside (contents side) dry-laminated with an adhesive. While this configuration can achieve the desired performance, it has the problem of being poorly recyclable due to the lamination of different materials, and therefore cannot be considered an environmentally friendly packaging material as described above.

[0005] Taking these points into consideration, studies are underway to see if an ideal packaging material design can be achieved using the same material that can be made into a single material and having the multifunctionality of a bag as described above.

[0006] In the design of polyester-based single-material packaging materials, a polyester-based sealant with improved low adsorption and heat resistance has been disclosed as an alternative to conventional polyolefin-based sealants (see, for example, Patent Document 1). The sealant of Patent Document 1 separates the heat-sealable layer from other layers and controls the raw material compositions of these layers separately, thereby satisfying heat-sealability and heat resistance. However, there is a problem that the heat-sealability is inferior to the seal strength of polyolefin-based sealants, and at present, it cannot withstand severe treatments such as boiling or retort processing in terms of heat resistance.

[0007] On the other hand, in the design of polyolefin-based single-material packaging materials, a polyolefin-based heat-seal resin can be used as a sealant, which has the advantage of ensuring sufficient heat-sealability compared to the above-mentioned polyester-based sealant. Since the sealant needs to exhibit sufficient sealability, it needs to have a certain thickness, and the proportion it occupies in the package is large. This is also a major reason for promoting the design of polyolefin-based single-material packaging materials. On the other hand, polyolefin-based packaging materials have a problem of inferior gas barrier performance compared to conventional packaging with barrier performance. Although polypropylene films have water vapor barrier properties, they are not sufficient compared to, for example, transparent inorganic vapor-deposited polyester films, which are generally considered to have excellent water vapor barrier properties, and there is also a problem that the oxygen barrier property is very poor.

[0008] In response to this, films have been used in which polypropylene films are laminated with polymer resin compositions that are generally said to have relatively high oxygen barrier properties, such as polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyvinylidene chloride resin, and polyacrylonitrile (see, for example, Patent Documents 2-4). However, gas barrier coated films using the above-mentioned polymer resin compositions of polyvinyl alcohol and ethylene vinyl alcohol copolymer have a large dependence on humidity, resulting in a decrease in gas barrier properties under high humidity conditions, and they also lack the heat and humidity resistance to withstand sterilization treatments such as boiling and retorting. Furthermore, while polyvinylidene chloride resin and polyacrylonitrile have low humidity dependence, they have problems such as insufficient absolute barrier values ​​and a high risk of generating harmful substances during disposal and incineration. In addition, the polypropylene films used do not have sufficient heat resistance, and the film expands and contracts due to heating during printing, lamination, and sterilization treatments, leading to wrinkles in appearance and a decrease in performance.

[0009] Regarding the improvement of the gas barrier properties of polypropylene films, attempts have been made to achieve stable gas barrier performance independent of humidity by laminating inorganic thin films (for example, Patent Document 5). However, there were problems such as inferior absolute gas barrier performance (especially oxygen barrier performance) compared to conventional polyester vapor-deposited films, and weakness to physical damage compared to the aforementioned coated type barrier films. In addition, barrier materials obtained by vapor deposition on polyolefin-based sealants have also been investigated (for example, Patent Document 6), but there were problems such as the fact that while water vapor barrier performance was obtained, oxygen barrier performance was insufficient. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2017-165059 [Patent Document 2] Japanese Patent Publication No. 2000-52501 [Patent Document 3] Japanese Patent Application Publication No. 4-359033 [Patent Document 4] Japanese Patent Publication No. 2003-231221 [Patent Document 5] WO2017 / 221781 [Patent Document 6] Patent No. 3318479 [Overview of the project] [Problems that the invention aims to solve]

[0011] In the aforementioned patent documents, it was difficult to achieve both monomaterialization of packaging materials and the various performance requirements for packaging materials, and it was not possible to design packaging materials that were both environmentally friendly and highly convenient.

[0012] This invention was made against the backdrop of the problems of the prior art described above. In other words, the objective of the present invention is to provide a packaging material that can form a laminate structure composed of resin species with low environmental impact, and that possesses the necessary performance characteristics required for packaging materials, such as gas barrier properties, heat sealability, and processability. [Means for solving the problem]

[0013] The inventors have discovered that by creating a laminated film in which a predetermined gas barrier layer tailored to the required performance is laminated onto a base film, the gas barrier performance can be greatly improved. Furthermore, by controlling the thermal elongation rate of the laminated film, heat resistance to various processing and sterilization treatments can be ensured. Finally, by laminating it with a sealant made of polyolefin components, it is possible to provide an environmentally friendly and highly convenient packaging material while maintaining high heat sealability, thus completing the present invention.

[0014] In other words, the present invention consists of the following configuration. 1. A packaging material comprising at least one base film mainly composed of a polyolefin resin and a heat-sealable resin layer, wherein at least one of the base films is a laminated base film having a gas barrier layer, and at least one of the base films peeled from the packaging material has a heating elongation of 6% or less in both the MD and TD directions at 130°C as measured by a thermomechanical analyzer, and an oxygen permeability of 60 ml / m² in a 23°C × 65% RH environment. 2 Packaging material characterized by having a pressure of d·MPa or less. 2. The packaging material according to 1, characterized in that the heat-sealable resin layer is made of a polyolefin resin whose main component is polypropylene or polyethylene resin. 3. The packaging material according to either 1. or 2., characterized by comprising two or more gas barrier layers. 4. The packaging material according to any one of 1 to 3, characterized in that the gas barrier layer is an inorganic thin film layer made of one of aluminum, aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide. 5. The packaging material according to any one of 1 to 4, characterized in that the gas barrier layer is a coating layer made of one of polyvinyl alcohol resin, polyester resin, or polyurethane resin. 6. The packaging material according to any one of claims 1 to 5, characterized in that an anchor coat layer is laminated between the base film and the gas barrier layer. 7. The packaging material according to any one of claims 1 to 6, characterized in that a protective layer is laminated on the gas barrier layer. 8. The packaging material according to any one of 1 to 7, characterized by using two or more of the base film. 9. A packaging material according to any one of 1 to 8, characterized in that the polyolefin resin constituting the base film contains 1% to 25% by weight of plant-derived polyethylene resin. 10. A packaging material according to any one of 1 to 9, characterized in that it is used for boiling or retorting. 11. A packaging material according to any one of 1 to 9, characterized in that it is used for microwave heating. 12. A packaging bag made using any of the packaging materials described in items 1 to 9 above. 13. A package in which an item to be packaged is packaged using the packaging material described in any of items 1 to 9 above, or the packaging bag described in item 12. [Effects of the Invention]

[0015] Through this technology, the inventors have made it possible to provide packaging materials that possess the necessary properties such as barrier properties, heat sealability, and heat resistance required for packaging materials, while also being environmentally conscious. [Modes for carrying out the invention]

[0016] The present invention relates to a packaging material comprising at least one base film mainly composed of a polyolefin resin and a heat-sealable resin layer, wherein at least one of the base films is a laminated film having a gas barrier layer, and at least one of the base films peeled from the packaging has a heating elongation of 6% or less in both the MD direction and the TD direction at 130°C, and has an oxygen permeability of 60 ml / m² in a 23°C × 65% RH environment. 2 The packaging material has a pressure of d·MPa or less. Furthermore, "consists of as the main component" means that it is contained in the component at a concentration of 50% by mass or more.

[0017] The present invention will be described in detail below. [Base film primarily composed of polyolefin resin] The packaging material of the present invention comprises a base film mainly composed of a polyolefin resin. The base film is preferably a base film mainly composed of a polypropylene resin (hereinafter referred to as a polypropylene resin film), and more preferably a stretched film. The stretched polypropylene resin film used as the base film in the present invention is preferably a biaxially oriented film, and its raw materials, mixing ratio, etc., are not particularly limited. For example, it may be a polypropylene homopolymer (propylene homopolymer), or a random copolymer or block copolymer with propylene as the main component and one or more selected from α-olefins such as ethylene, butene, pentene, and hexene, or a mixture of two or more of these polymers. In addition, known additives such as antioxidants, antistatic agents, and plasticizers may be added for the purpose of modifying physical properties, and for example, petroleum resins or terpene resins may be added.

[0018] In the present invention, the polypropylene-based resin constituting the base film is preferably a propylene homopolymer that substantially does not contain comonomers other than propylene, and even if it contains comonomers, the amount of comonomers is preferably 0.5 mol% or less. The upper limit of the amount of comonomers is more preferably 0.3 mol%, and even more preferably 0.1 mol%. Within the above range, crystallinity is improved, dimensional changes at high temperatures are reduced, that is, the elongation rate when heated to a certain temperature (hereinafter referred to as the heating elongation rate) is reduced, and heat resistance is improved. In addition, a small amount of comonomers may be included as long as it does not significantly reduce crystallinity.

[0019] Furthermore, the biaxially oriented polypropylene resin film used in the present invention may be a single-layer film or a laminated film. However, in order to achieve the objectives of the present invention, a laminated film is preferable, and the type of laminate, the number of layers, the lamination method, etc., are not particularly limited and can be arbitrarily selected from known methods. However, it is preferable to improve the lamination strength and the adhesive strength of coating agents, etc., by controlling the surface roughness and flexibility of the base film surface.

[0020] As a means of improving the lamination strength of the base film and the interfacial adhesion strength with inorganic thin film layers, coating agents, etc., a mixture of two or more polypropylene resins with different melt flow rates (MFRs) may be used as the polypropylene resin constituting the surface layer of the base film.

[0021] It is hypothesized that a smaller difference in melt flow rates (MFRs) between two or more polypropylene resins in a polypropylene resin mixture results in less variation in the crystallization rates and degree of crystallinity of each polypropylene resin, making it easier for minute surface irregularities to form. However, care must be taken because slow cooling rates of the unstretched sheet during film manufacturing can lead to larger surface irregularities due to spherulites, and excessively high stretching temperatures during longitudinal or transverse stretching can also easily result in larger surface irregularities.

[0022] As the respective polypropylene resins, polypropylene homopolymers that do not contain copolymer components, and polypropylene resins copolymerized with ethylene and / or α-olefins having 4 or more carbon atoms in an amount of 5.0 mol% or less can be used. The copolymer component of the copolymerized polypropylene resin is preferably 4.0 mol% or less, more preferably 3.5 mol% or less. The copolymer component of the copolymerized polypropylene resin is preferably 1.0 mol% or more, more preferably 1.5 mol% or more, even more preferably 2.0 mol% or more, and particularly preferably 2.5 mol% or more. Examples of α-olefins having four or more carbon atoms include 1-butene, 1-hexene, 4-methyl·1-pentene, and 1-octene. Other copolymerization components, such as polar maleic acid, may also be used.

[0023] From a practical standpoint, the lower limit of xylene-soluble content in the polypropylene resin constituting the base film is preferably 0.1% by mass. The upper limit of xylene-soluble content is preferably 7% by mass, more preferably 6% by mass, and even more preferably 5% by mass. Within these ranges, crystallinity is improved, the thermal elongation is reduced, and the heat resistance is improved.

[0024] In the present invention, the lower limit of the melt flow rate (MFR) (230°C, 2.16 kgf) of the polypropylene resin is preferably 0.5 g / 10 min. More preferably, the lower limit of the MFR is 1.0 g / 10 min, even more preferably 2.0 g / 10 min, particularly preferably 4.0 g / 10 min, and most preferably 6.0 g / 10 min. Within this range, the mechanical load is small, and extrusion and stretching are easy. The upper limit of the MFR is preferably 20 g / 10 min. More preferably, the upper limit of the MFR is 17 g / 10 min, even more preferably 16 g / 10 min, and particularly preferably 15 g / 10 min. Within this range, stretching is easy, thickness variations are reduced, the stretching temperature and heat setting temperature can be increased, the heat elongation is smaller, and the heat resistance is improved.

[0025] The aforementioned base film may be a uniaxially oriented film in the longitudinal direction (MD direction) or transverse direction (TD direction) from the viewpoint of heat resistance, but a biaxially oriented film is preferred. In the present invention, by using the preferred raw materials described above and stretching at least uniaxially, a film with high heat resistance and low elongation at high temperatures, which could not be expected with conventional polypropylene films, can be obtained. Examples of stretching methods include simultaneous biaxial stretching and sequential biaxial stretching, but sequential biaxial stretching is preferred from the viewpoint of providing good flatness, dimensional stability, and thickness uniformity.

[0026] In the sequential biaxial stretching method, polypropylene resin is heated and melted in a single-screw or twin-screw extruder to a resin temperature of 200°C to 280°C, formed into a sheet using a T-die, and extruded onto a chill roll at a temperature of 10°C to 100°C to obtain an unstretched sheet. Next, it is roll-stretched in the longitudinal direction (MD direction) at 120°C to 165°C to 3.0 to 8.0 times its original size. Subsequently, after preheating in a tenter, it can be stretched in the transverse direction (TD direction) at a temperature of 155°C to 175°C to 4.0 to 20.0 times its original size. Furthermore, after biaxial stretching, a heat-setting treatment can be performed at a temperature of 165°C to 175°C while allowing for a relaxation of 1% to 15%.

[0027] In the present invention, it is preferable that the thermal elongation of the base film at 130°C, as measured by a thermomechanical analyzer, is 10% or less in both the MD and TD directions. This reduces deformation of the base film due to thermal load when the film is under tension during the processing and lamination processes of the gas barrier layer described later. As a result, gas barrier performance and appearance quality such as wrinkles and sagging can be further improved. The thermal elongation in the MD and TD directions at 130°C is preferably 9.5% or less, more preferably 9.0% or less, and even more preferably 8.5% or less, with a lower limit of 0% being preferable. If the thermal elongation at 130°C is outside the above range, the laminated film may deform due to the heat under tension load, reducing gas barrier properties, or the dimensional changes of the film may occur, resulting in a decrease in appearance quality. In the present invention, thermal elongation is a value measured by a thermomechanical analyzer (TMA), and is described in more detail by the method described in the examples.

[0028] In order to achieve the aforementioned heat elongation within the aforementioned range in the base film of the present invention, it is preferable to manufacture the film by the following method. First, the upper limit of the stretching temperature in the longitudinal direction (MD) is preferably the film melting point (Tm) - 7°C, more preferably Tm - 10°C, and even more preferably Tm - 12°C. Within this range, it is easier to reduce the heat elongation, and the film does not fuse to the stretching rolls and become difficult to stretch, so the quality does not deteriorate. In addition, stretching in the longitudinal direction may be performed in two or more stages using three or more pairs of stretching rolls. Dividing the stretching into multiple stages reduces strain during stretching, making it easier to reduce the heat elongation.

[0029] The upper limit of the stretch ratio in the width direction (TD) is preferably 15 times, more preferably 12 times, and even more preferably 10 times. If it exceeds this limit, the heat elongation rate increases, and the material becomes more prone to breakage during stretching. Furthermore, the lower limit of the TD stretching temperature is preferably 150°C, more preferably 152°C, even more preferably 154°C, and particularly preferably 156°C. At temperatures above 150°C, the material is stretched in a sufficiently softened state, making it easier to reduce the heat elongation. The upper limit of the TD stretching temperature is preferably 164°C, more preferably 162°C, and even more preferably 160°C. Higher temperatures are preferable to reduce the heat elongation.

[0030] The lower limit of the heat-fixing temperature after stretching in the width direction (TD) is preferably 168°C, more preferably 170°C, and even more preferably 173°C. If the temperature is 168°C or higher, the heat elongation rate does not tend to increase, and it is not necessary to perform long processing times to reduce the heat elongation rate.

[0031] It is preferable to relax the material during heat setting. The lower limit of the relaxation rate is preferably 2%, and more preferably 3%. If it is lower than the above, the heat expansion rate may increase.

[0032] Furthermore, to reduce the thermal shrinkage rate, the film manufactured in the above process can be wound into a roll and then annealed offline.

[0033] In the present invention, it is preferable to incorporate particles into the base film to form protrusions on the film surface in order to impart handling properties (e.g., windability after lamination). Examples of particles to be incorporated into the film include inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, and alumina, and heat-resistant polymer particles such as acrylic, PMMA, nylon, polystyrene, polyester, and benzoguanamine-formaldehyde condensate. From the viewpoint of transparency, it is preferable that the particle content in the film be low, for example, 1 ppm to 1000 ppm. Furthermore, the preferred average particle diameter is 1.0 to 3.0 μm, and more preferably 1.0 to 2.7 μm. The method for measuring the average particle size here is to take a photograph with a scanning electron microscope, measure the horizontal Ferret diameter using an image analyzer, and display the average value. Furthermore, from the viewpoint of transparency, it is preferable to select particles with a refractive index close to that of the resin used. Furthermore, the film may contain antioxidants, ultraviolet absorbers, antistatic agents, dyes, lubricants, nucleating agents, adhesives, anti-fogging agents, flame retardants, anti-blocking agents, inorganic or organic fillers, etc., in order to impart various functions as needed.

[0034] In addition to the polypropylene resin used in the present invention, other resins may be used as long as they do not impair the objectives of the present invention, for purposes such as improving the mechanical properties of the base film, improving adhesion to the ink layer and adhesive layer laminated on the gas barrier coating layer, and reducing environmental impact. Examples include polyethylene resin, polypropylene resins other than those mentioned above, random copolymers which are copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers.

[0035] In the present invention, the polyethylene resin that can be used for the base film is a resin mainly composed of ethylene. For example, any ethylene homopolymer such as high-pressure low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene can be used. In addition, crystalline, low-crystalline, or amorphous random or block copolymers, or mixtures thereof, of monomers such as propylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, vinyl acetate, (meth)acrylic acid, and (meth)acrylic acid esters can be used.

[0036] The polyethylene resin is preferably present in an amount of 1% to 25% by mass relative to 100% of the total amount of polypropylene resin and polyethylene resin constituting the base material. An amount of 1% by mass or more improves heat seal strength, blocking resistance, and anti-fogging properties. More preferably 5% by mass or more, and even more preferably 8% by mass or more. An amount of 20% by mass or less makes it easier to maintain rigidity. More preferably 18% by mass or less, and even more preferably 15% by mass or less.

[0037] The melting point of polyethylene resin is preferably in the range of 100°C to 135°C, and more preferably 105°C to 130°C, from the viewpoint of heat resistance, transparency, mechanical properties, and film-forming properties. The density is measured in accordance with JIS K7112 and is 0.90 g / cm³. 3 More than 0.94g / cm 3 The following is preferable: 0.91 g / cm³ 3 More than 0.94g / cm 3 The following are preferable. The melt flow rate (MFR) (190°C, 2.16 kgf) is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and even more preferably 2 g / 10 min or more. From the viewpoint of further stabilizing moldability, it is preferably 20 g / 10 min or less, more preferably 15 g / 10 min or less, and even more preferably 10 g / 10 min or less.

[0038] From the viewpoint of low environmental impact, it is particularly preferable to use a plant-derived polyethylene resin in the polyethylene resin of the present invention. The bio-basedness of the polyethylene resin, as measured in accordance with ISO 16620, is preferably 50% to 100%, preferably 70% to 100%, and more preferably 80% to 100%.

[0039] In the present invention, the thickness of the base film can be arbitrarily set according to each application, but the lower limit is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 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 too thin, handling is likely to be poor. On the other hand, if the thickness is too thick, not only are there cost issues, but when the film is wound up in a roll for storage, poor flatness due to curling is likely to occur.

[0040] The haze of the base film of the present invention is preferably transparent from the viewpoint of visibility of the contents, specifically preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less. The haze tends to worsen when, for example, the stretching temperature or heat setting temperature is too high, the cooling roll (CR) temperature is high and the cooling rate of the stretched raw material sheet is slow, or there is too much low molecular weight, so it can be controlled within the above range by adjusting these factors.

[0041] Furthermore, the base film layer in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, etc., as long as the objective of the present invention is not impaired, and may also be subjected to known anchor coating treatments, printing, decoration, etc. Generally, it is preferable to use a resin with good adhesion such as polyurethane or polyester for the anchor coating, but the anchor coating layer for improving the barrier in the present invention will be described later.

[0042] The packaging material of the present invention requires at least one base film having a gas barrier layer. However, it is more preferable to laminate two or more base films because it is expected to improve the toughness and gas barrier performance as a packaging material. In terms of toughness, generally, by using two polypropylene-based biaxially stretched films having the characteristic of high puncture strength, for example, a packaging material design comparable to that using two different materials of polyester film and polyamide film, which are widely used as packaging materials, can be achieved. Also, in terms of gas barrier properties, by using two base films, the film located in the middle is less likely to be affected by the external environment, such as temperature and humidity and external bending, and can exhibit more stable gas barrier performance. In that sense, when using two base films, it is particularly preferable that the coating layer or the inorganic thin film layer having gas barrier performance is laminated on the middle film.

[0043] [Gas barrier layer] In the present invention, at least one of the base films needs to be a laminated base film having a gas barrier layer. As the gas barrier layer, it is necessary 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, which will be described later. Furthermore, for the purpose of assisting the barrier property of the gas barrier layer, an anchor coat (C) and a protective layer (D) described later can also be laminated in combination.

[0044] [Coating layer (A)] In the present invention, a coating layer (A) can be provided as the gas barrier layer. However, in the present invention, it is necessary to design while paying attention to the increase in cost due to the increase in the process by providing the coating layer (A), and the environmental load such as the difficulty of recycling depending on the film thickness.

[0045] The coating amount of the coating layer (A) is preferably 0.10 to 0.70 (g / m 2 ). The lower limit of the coating amount of the coating layer (A) is preferably 0.15 (g / m 2 ) or more, and more preferably 0.20 (g / m 2) or more, more preferably 0.25 (g / m²) 2 ) or more, and the upper limit is preferably 0.65 (g / m³). 2 ) or less, more preferably 0.60 (g / m³) 2 ) or less, more preferably 0.55 (g / m 2 ) or less. The amount of coating layer (A) attached is 0.70 (g / m 2 When the thickness exceeds 0.10 (g / m²), the gas barrier properties improve, but the cohesive force within the coating layer becomes insufficient, and the uniformity of the coating layer also decreases, which can result in unevenness (haze increase, whitening) or defects in the coating appearance, and may prevent the gas barrier properties and adhesion from being fully realized. In terms of processability, the thicker film thickness may cause blocking. Furthermore, there are concerns that it may negatively affect the recyclability of the film, and the increased use of raw materials and solvents will increase the environmental burden. On the other hand, when the film thickness of the coating layer (A) is 0.10 (g / m²), 2 If the value is less than ), sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0046] A polyvinyl alcohol polymer is preferred as the resin composition used for the coating layer (A) formed on the surface of the laminated film of the present invention. Polyvinyl alcohol polymers mainly consist of vinyl alcohol units, and a significant improvement in barrier performance can be expected due to their high cohesiveness based on hydrogen bonding structures. The degree of polymerization and degree of saponification of the polyvinyl alcohol polymer are determined based on the desired gas barrier properties and the viscosity of the coating aqueous solution. Regarding the degree of polymerization, a value of 2600 or less is preferred for ease of coating, as high viscosity of the aqueous solution and tendency to gel make coating difficult. Regarding the degree of saponification, if it is less than 90%, sufficient oxygen gas barrier properties cannot be obtained under high humidity, and if it exceeds 99.7%, it is difficult to prepare the aqueous solution, prone to gelation, and unsuitable for industrial production. Therefore, a degree of saponification of 90 to 99.7% is preferred, and more preferably 93 to 99%. Furthermore, in the present invention, various copolymerized or modified polyvinyl alcohol polymers, such as polyvinyl alcohol polymers copolymerized with ethylene and polyvinyl alcohol polymers modified with silanol, can also be used, as long as they do not impair processability or productivity.

[0047] 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 create a labyrinthine effect on gases, thereby improving gas barrier properties. Furthermore, the addition of an inorganic layered compound can suppress the humidity dependence of the gas barrier properties. Examples of materials include clay minerals (including their synthetic products) such as smectite, kaolin, mica, hydrotalcite, and chlorite. Specifically, examples include montmorillonite, beiderite, saponite, hectorite, souconite, stevensite, kaolinite, nacrite, dickite, halloysite, hydrated halloysite, tetrasilicic mica, sodium teniolite, muscovite, margalite, phlogopite, talc, antigorite, chrysotile, pyrophyllite, vermiculite, xanthophyllite, and chlorite. Furthermore, flake silica and the like can also be used as inorganic layered compounds. These may be used individually or in combination of two or more. Among these, smectite (including its synthetic products) is particularly preferred because of its high effectiveness in improving water vapor barrier properties.

[0048] Furthermore, as the inorganic layered compound, it is preferable that it contains redox metal ions, particularly iron ions. Among such compounds, montmorillonite, a type of smectite, is preferred in terms of coating suitability and gas barrier properties. As the montmorillonite, known types that have been conventionally used as gas barrier agents can be used. For example, the following general formula: (X,Y)2~3Z4O10(OH)2·mH2O·(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. H2O represents intercalated water. m and ω represent positive real numbers.) Among these, the one in which W in the formula is Na is preferred because it cleaves in an aqueous medium.

[0049] The size and shape of the inorganic layered compound are not particularly limited, but the particle size (longest diameter) 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, the dispersibility will be poor, which may result in deterioration of the coating properties and appearance of the coating layer (A). On the other hand, the aspect ratio is 50 to 5000, more preferably 100 to 4000, and even more preferably 200 to 3000.

[0050] The mixing ratio of the resin composition to the inorganic layered compound in the coating layer of the present invention is preferably 75 / 25~35 / 65 (wt%), more preferably 70 / 30~40 / 60 (wt%), and even more preferably 65 / 35~45 / 55 (wt%). If the mixing ratio of the inorganic layered compound is less than 25%, the barrier performance may be insufficient. On the other hand, if it is more than 65%, dispersibility will be poor, which may lead to deterioration of coating properties and adhesion.

[0051] The coating layer (A) of the present invention may contain various crosslinking agents to improve the cohesive strength of the film and its resistance to moisture and heat adhesion, provided that such agents 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, and the like. Among these, silicon-based crosslinking agents are particularly preferred because they can be crosslinked with resin compositions and inorganic thin film layers that have hydroxyl groups, thereby improving water-resistant adhesion. Commonly used silicon-based crosslinking agents include metal alkoxides and silane coupling agents. Metal alkoxides are compounds that can be represented by the general formula M(OR)n (M: metal such as Si or Al, R: alkyl group such as CH3 or C2H5). Specifically, examples include tetraethoxysilane [Si(OC2H5)4] and triisopropoxyaluminum Al[OCH(CH3)2]3. Examples of silane coupling agents include those having epoxy groups such as 3-glycidoxypropyltrimethoxysilane, those having amino groups such as 3-aminopropyltrimethoxysilane, those having mercapto groups such as 3-mercaptopropyltrimethoxysilane, those having isocyanate groups such as 3-isocyanatetopropyltriethoxysilane, and tris-(3-trimethoxysilylpropyl)isocyanurate. In addition, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc. may be used in combination as crosslinking agents. However, when recyclability is important, the amount of crosslinking agent should be carefully considered.

[0052] When a crosslinking agent is incorporated, the amount is preferably 0.05 to 4.00% by mass in the coating layer, more preferably 0.10 to 3.50% by mass, and even more preferably 0.15 to 3.00% by mass. Within this range, the film hardens, improving cohesiveness, resulting in a film with excellent water-resistant adhesion. If the amount exceeds 3.00% by mass, the amount of uncrosslinked portions increases, and excessive hardening can make the film too hard, potentially reducing adhesion. On the other hand, if the amount is less than 0.05% by mass, sufficient cohesiveness may not be achieved.

[0053] In this invention, the film haze 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 the visibility of the contents. If the haze is greater than 20%, in addition to a significant deterioration in transparency, 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 was evaluated in accordance with JIS K7136, using a turbidimeter (NDH2000, manufactured by Nippon Denshoku).

[0054] The coating method for the resin composition for the coating layer is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0055] 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 first evaporate the solvent, and then perform the main drying 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 below 80°C, the coating layer may not dry completely. If the pre-drying temperature is above 110°C, drying may proceed before the coating layer has a chance to spread evenly, potentially resulting in a poor appearance.

[0056] On the other hand, the drying temperature is preferably 110 to 140°C, more preferably 115 to 135°C, and even more preferably 120 to 130°C. If the drying temperature is below 110°C, the film formation of the coating layer (A) will not proceed, reducing cohesiveness and adhesion, which may negatively affect the barrier properties. If the temperature exceeds 140°C, the film may be subjected to too much heat, making it brittle or causing large wrinkles due to thermal shrinkage.

[0057] The preferred drying time for pre-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 the main drying is also 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, it is important to note that the drying conditions may vary depending on the type of heat transfer medium and the intake and exhaust conditions of the drying oven. In addition to drying, applying an additional heat treatment for 1 to 4 days at the lowest possible temperature range, specifically in the 40 to 60°C temperature range, is even more effective in promoting the formation of the coating layer (A).

[0058] [Inorganic thin film layer (B)] In the present invention, an inorganic thin film layer (B) can be provided on the surface of the substrate film as a gas barrier layer. The inorganic thin film layer (B) is a thin film made of a metal or an inorganic oxide. The material used to form the inorganic thin film layer is not particularly limited as long as it can be made into a thin film, but from the viewpoint of gas barrier properties, inorganic oxides such as silicon dioxide (silica), aluminum oxide (alumina), and mixtures of silicon dioxide and aluminum oxide are preferred. In particular, a composite oxide of silicon dioxide and aluminum oxide is preferred because it can achieve both flexibility and density in the thin film layer. In this composite oxide, the mixing ratio of silicon dioxide and aluminum oxide is preferably in the range of 20 to 70% by mass of Al in terms of the mass ratio of the metal content. If the Al concentration is less than 20% by mass, the water vapor barrier properties may be low. On the other hand, if it exceeds 70% by mass, the inorganic thin film layer tends to harden, and there is a risk that the film will be destroyed during secondary processing such as printing or lamination, reducing the gas barrier properties. In this context, silicon oxide refers to various silicon oxides such as SiO and SiO2, or mixtures thereof, while aluminum oxide refers to various aluminum oxides such as AlO and Al2O3, or mixtures thereof.

[0059] The thickness of the inorganic thin film layer (B) is typically 1 to 100 nm, preferably 5 to 50 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, if it is made excessively thick beyond 100 nm, the corresponding improvement in gas barrier properties cannot be obtained, and it may even be disadvantageous in terms of flexibility and manufacturing costs.

[0060] There are no particular restrictions on the method for forming the inorganic thin film layer (B). For example, any known deposition method such as vacuum deposition, sputtering, ion plating, or other physical deposition methods (PVD), or chemical deposition (CVD), can be used as appropriate. Below, a typical method for forming the inorganic thin film layer (B) will be described using a silicon oxide / aluminum oxide thin film as an example. For example, when using vacuum deposition, a mixture of SiO2 and Al2O3, or a mixture of SiO2 and Al, is preferably used as the deposition raw material. These deposition raw materials are usually particles, and it is desirable that the size of each particle is such that the pressure during deposition does not change, with a preferred particle size of 1 mm to 5 mm. For heating, methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating can be used. It is also possible to use reactive deposition by introducing oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, etc. as a reaction gas, or by using means such as ozone addition or ion assistance. Furthermore, the film deposition conditions can be arbitrarily changed, such as by applying a bias to the substrate (the laminated film used for deposition) or by heating or cooling the substrate. These deposition materials, reaction gases, bias, heating / cooling of the substrate can also be similarly modified when using sputtering or CVD methods.

[0061] [Anchor coat layer (C)] In the present invention, when the aforementioned gas barrier layers are laminated, an anchor coat layer (C) may be provided as an auxiliary layer to provide sufficient gas barrier properties and adhesion. By providing an anchor coat layer, the exposure of oligomers and antiblocking materials from the polypropylene resin can be suppressed. Furthermore, when other layers are laminated on top of the anchor coat layer (C), the adhesion between layers can be increased. In particular, in the formation of an inorganic thin film layer, not only is adhesion improved, but the formation of the inorganic layer is promoted by smoothing the surface, and an effect of improving gas barrier properties can also be expected. In addition, by using a material that has a certain degree of gas barrier properties (referred to as gas barrier auxiliary properties) in the anchor coat layer (C) itself, the gas barrier performance of the film when the aforementioned gas barrier layers are laminated can be greatly improved. Furthermore, since the anchor coat layer (C) prevents hot water from entering the substrate, whitening of the film after boiling or retorting can also be reduced.

[0062] When only the anchor coat layer (C) is laminated, the gas barrier assisting properties of the film are such that the oxygen permeability in a 23°C × 65%RH environment is 10,000 ml / m². 2 A pressure of d·MPa or less is preferable in that it exhibits good gas barrier properties after the aforementioned gas barrier layer is laminated. More preferably, it is 9000 ml / m². 2 d·MPa or less, more preferably 8000 ml / m³ 2 It can be set to d·MPa or less. Oxygen permeability of 10,000 ml / m³ 2 If the pressure exceeds d·MPa, sufficient barrier performance cannot be obtained even after lamination of the gas barrier layer, making it difficult to meet the requirements for applications that demand high gas barrier properties.

[0063] In this invention, the amount of anchor coat layer (C) attached is 0.10 to 0.50 g / m 2 This is preferable. This allows for uniform control of the anchor coat layer (C) during coating, resulting in a film with fewer coating inconsistencies and defects. Furthermore, the anchor coat layer (C) contributes to suppressing oligomer surface expression, stabilizing haze after moist heat. The amount of anchor coat layer (C) is preferably 0.15 g / m².2 More precisely, 0.20 g / m 2 More preferably 0.35 g / m 2 The above is preferable, and preferably 0.50 g / m 2 More preferably, 0.45 g / m 2 More preferably, 0.40 g / m 2 The following applies: The amount of anchor coat layer (C) attached is 0.50 g / m². 2 Beyond this point, while gas barrier assistance improves, the cohesive force within the anchor coat layer becomes insufficient, and the uniformity of the anchor coat layer decreases, resulting in unevenness and defects in the coat's appearance. Furthermore, in terms of processability, the thicker film thickness may cause blocking and increase manufacturing costs. Moreover, there are concerns about negative impacts on the recyclability of the film, and the increased use of raw materials and solvents strengthens the environmental burden. On the other hand, if the thickness of the anchor coat layer (C) is 0.10 g / m², 2 If the value is less than this, sufficient gas barrier support and interlayer adhesion may not be obtained.

[0064] Examples of resin compositions used in the anchor coat layer (C) of the present invention include those obtained by adding a curing agent such as epoxy, isocyanate, or melamine to a resin such as urethane, polyester, acrylic, titanium, isocyanate, imine, or polybutadiene. Furthermore, crosslinking agents such as silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, or epoxy compounds may be included. In particular, the inclusion of urethane resin is preferable because, in addition to the barrier performance due to the high cohesiveness of the urethane bonds themselves, the polar groups interact with the inorganic thin film layer, and the presence of amorphous portions provides flexibility, thus suppressing damage when bending loads are applied. Polyester resin is also preferable because similar effects can be expected. In the present invention, it is particularly preferable to include polyurethane composed of polyester + isocyanate, and it is even more preferable to add a silicon-based crosslinking agent from the viewpoint of improving adhesion.

[0065] The urethane resin used in the anchor coat layer (C) of the present invention is more preferably a urethane resin containing aromatic or aromatic aliphatic diisocyanate components as its main constituents, from the viewpoint of gas barrier assisting properties. Among these, it is particularly preferable to contain a metaxylylene diisocyanate component. By using the above resin, the cohesive force of the urethane bonds can be further enhanced by the stacking effect between aromatic rings, and as a result, good gas barrier assisting properties can be obtained.

[0066] In the present invention, it is preferable that the proportion of aromatic or aromatic aliphatic diisocyanate in the urethane resin used in the anchor coat layer (C) be in the range of 50 mol% or more (50 to 100 mol%) of 100 mol% of the polyisocyanate component. The proportion of the total amount of aromatic or aromatic aliphatic diisocyanate is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, and even more preferably 80 to 100 mol%. If the proportion of the total amount of aromatic or aromatic aliphatic diisocyanate is less than 50 mol%, good gas barrier assistance may not be obtained.

[0067] The urethane resin used in the anchor coat layer (C) of the present invention may contain various crosslinking agents for the purpose of improving the cohesive strength of the film and improving its moisture- and heat-resistant adhesion. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, and epoxy compounds. Among these, silicon-based crosslinking agents are particularly preferred from the viewpoint of improving water-resistant adhesion to the inorganic thin film layer. Other crosslinking agents such as oxazoline compounds, carbodiimide compounds, and epoxy compounds may also be used in combination.

[0068] As silicon-based crosslinking agents, silane coupling agents are preferred from the viewpoint of crosslinking inorganic and organic substances. Suitable silane coupling agents include hydrolyzable alkoxysilane compounds, such as halogen-containing alkoxysilanes (chloroC2-4 alkyltriC1-4 alkoxysilanes such as 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, etc.), and alkoxysilanes having epoxy groups [2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane]. Glycidyloxy C2-4 alkyl triC1-4 alkoxysilanes such as 3-glycidyloxypropyltriethoxysilane, glycidyloxydiC2-4 alkyldiC1-4 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 trimethoxysilane, amino group-containing alkoxysilanes [aminoC2-4 alkyltriC1-4 alkoxysilanes such as 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc., aminoC2-4 alkyltriC1-4 alkoxysilanes such as 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, etc., 2-[N-(2-aminoethyl)aminoethyl [N-(2-aminoethyl)amino]propyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltriethoxysilane, etc. (2-aminoC2-4 alkyl)aminoC2-4 alkyltriC1-4 alkoxysilanes, etc. (aminoC2-4 alkyl)aminodiC2-4 alkyldiC1-4 alkoxysilanes, etc., 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane, 3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane, etc.]Alkoxysilanes having a mercapto group (mercapto C2-4 alkyl triC1-4 alkoxysilanes such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc., mercapto diC2-4 alkyl diC1-4 alkoxysilanes such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc.), alkoxysilanes having a vinyl group (vinyl triC1-4 alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.), ethylene Examples of silane coupling agents include alkoxysilanes having an amino group [such as (meth)acryloxy C2-4 alkyltriC1-4 alkoxysilanes like 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, etc., and (meth)acryloxydiC2-4 alkyldiC1-4 alkoxysilanes like 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, etc.]. These silane coupling agents can be used alone or in combination of two or more. Among these silane coupling agents, silane coupling agents having an amino group are preferred.

[0069] The silicon-based crosslinking agent is preferably added to the coating layer in an amount of 0.05 to 4.00% by mass, more preferably 0.10 to 3.50% by mass, and even more preferably 0.15 to 3.00% by mass. The addition of the silicon-based crosslinking agent promotes hardening of the film and improves its cohesive force, resulting in a film with excellent water-resistant adhesion, and is also expected to prevent the expression of oligomers. If the amount added exceeds 3.00% by mass, the film hardens and the cohesive force improves, but some unreacted areas may occur, potentially reducing the adhesion between layers. On the other hand, if the amount added is less than 0.05% by mass, sufficient cohesive force may not be obtained.

[0070] 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 provides sufficient film toughness, coating suitability, and solvent solubility as a coating material, but its number average molecular weight is 1,000 to 50,000, more preferably 1,500 to 30,000. The functional groups at the polyester ends are also not particularly limited; they may be alcohol ends, carboxylic acid ends, or a combination of both. However, when using an isocyanate-based curing agent in combination, it is necessary to use a polyester polyol primarily composed of alcohol ends.

[0071] 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 becomes sticky after the coating operation, making blocking more likely and making the winding operation after coating difficult. If the Tg is below 10°C, it becomes difficult to prevent blocking even with the addition of a blocking prevention material, and even under high pressure conditions near the winding core. A more preferable Tg temperature is 15°C or higher, and even more preferably 20°C or higher.

[0072] The polyester resin used in the anchor coat layer (C) of the present invention is obtained by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The polycarboxylic acid component of the polyester resin used in the present invention is characterized by containing at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. Ortho orientation improves solubility in solvents, making it possible to coat the substrate uniformly. A uniformly coated film has less variation in barrier performance, which in turn contributes 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 moist heat treatment and leads to the suppression of oligomers. Aromatic polycarboxylic acids in which the carboxylic acid is substituted at the ortho position, or their anhydrides, include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracenecarboxylic acid or its anhydride. These compounds may have substituents on any carbon atom of the aromatic ring. Examples of substituents include chloro group, bromo group, methyl group, ethyl group, i-propyl group, hydroxyl group, methoxy group, ethoxy group, phenoxy group, methylthio group, phenylthio group, cyano group, nitro group, amino group, phthalimide group, carboxyl group, carbamoyl group, N-ethylcarbamoyl group, phenyl group, or naphthyl group. Furthermore, polyester polyols in which the content of these polycarboxylic acids is 70 to 100 mol% of the total polycarboxylic acid components are particularly preferred because they have a high barrier-improving effect and excellent solvent solubility, which is essential for coating materials.

[0073] In this invention, other polycarboxylic acid components may be copolymerized to the extent that the effects of the invention are not impaired. Specifically, as aliphatic polycarboxylic acids, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, etc.; as unsaturated bond-containing polycarboxylic acids, maleic anhydride, maleic acid, fumaric acid, etc.; as alicyclic polycarboxylic acids, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc.; as aromatic polycarboxylic acids, 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 anhydrides, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid and their anhydrides or ester-forming derivatives; polybasic acids such as p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid and their ester-forming derivatives can be used alone or in mixtures of two or more. In particular, 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.

[0074] 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 is possible to synthesize a polyester that exhibits gas barrier replenishment performance. However, it is preferable that the polyhydric alcohol component contains 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 presumed that the fewer the number of carbon atoms between oxygen atoms, the less the molecular chain becomes excessively flexible and the less oxygen permeable it is, so it is most preferable to use ethylene glycol as the main component.

[0075] In the present invention, it is preferable to use the polyhydric alcohol components described above, but other polyhydric alcohol components may also be copolymerized as long as they do not impair the effects of the present invention. Specifically, 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, while examples of trihydric or higher alcohols include glycerol, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl) isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythulitol. In particular, among the trihydric alcohols, polyesters using glycerol and tris(2-hydroxyethyl) isocyanurate in combination are especially preferred because they have good organic solvent solubility due to their branched structure and moderately high crosslink density, as well as excellent barrier function.

[0076] Examples of catalysts used in the reaction to obtain the polyester of the present invention include tin-based catalysts such as monobutyl tin oxide and dibutyl tin oxide, titanium-based catalysts such as tetra-isopropyl titanate and tetra-butyl titanate, and acid catalysts such as zirconia-based catalysts such as tetra-butyl zirconate. It is preferable to use a combination of the above-mentioned titanium-based catalysts, such as tetra-isopropyl titanate and tetra-butyl titanate, which have high activity for esterification reactions, and the above-mentioned zirconia catalyst. The amount of catalyst used is 1 to 1000 ppm relative to the total mass of the reaction raw materials used, and more preferably 10 to 100 ppm. If the amount is less than 1 ppm, the catalytic effect is difficult to obtain, and if it exceeds 1000 ppm, problems may arise in which the urethane formation reaction is inhibited when an isocyanate curing agent is used.

[0077] In this invention, when 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, since the coating layer becomes cross-linked, there is the advantage of improved heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use for boiling and retort packaging. On the other hand, there are problems such as the inability to reuse the liquid after mixing with the curing agent and the necessity of a curing (aging) process after coating. As an advantage, for example, when used as a simple overcoat varnish, there is no risk of thickening of the coating liquid, the manufacturing process is easy to control, the coating liquid can be diluted and reused, and in addition, a curing process (so-called aging process) is unnecessary. In this case, the ends of the polyester used can be polyols, polycarboxylic acids, or mixtures of both without any problems. On the other hand, because the resin of the coating layer is linear, there may be cases where the heat resistance and abrasion resistance are insufficient, or problems may arise where it is difficult to use for boiling or retort packaging.

[0078] When a curing agent is used in the coating layer, an isocyanate curing system is preferred from the viewpoint of the heat resistance of the film, as it is a coating on a film. In this case, the resin component of the coating material must be polyester polyol. On the other hand, when an epoxy compound is used as the curing agent, it must be polyester polycarboxylic acid. In these cases, the coating layer becomes cross-linked, which has the advantage of improving heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use for boiling and retort packaging. However, there are also problems such as the inability to reuse the liquid after mixing with the curing agent and the necessity of a curing (aging) process after coating.

[0079] The polyisocyanate compound used in this invention, when the polyester has hydroxyl groups, reacts with at least a portion of it to form a urethane structure, thereby increasing the polarity of the resin component and further enhancing the gas barrier function by agglomerating the polymer chains. 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 this 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 from the viewpoint of improving the gas barrier function if part of the skeleton contains an aromatic ring or an aliphatic ring. For example, 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, norborn diisocyanate, or trimers of these isocyanate compounds; and end-isocyanate group-containing compounds 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.

[0080] The method for forming the anchor coat layer (C) is not particularly limited, and conventionally known methods such as coating methods can be employed. Among coating methods, preferred methods include the offline coating method and the in-line coating method. For example, in the case of the in-line coating method performed in the process of manufacturing the base film layer, the drying and heat treatment conditions during coating depend on the coating thickness and the conditions of the equipment, but it is preferable to immediately send the material to the stretching process in the perpendicular direction after coating and dry it in the preheating zone or stretching zone of the stretching process, and in such cases it is usually preferable to set the temperature to about 50 to 250°C.

[0081] The coating method for the resin composition for the anchor coat layer (C) is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0082] When forming the anchor coat layer (C), it is preferable to apply the resin composition for the anchor coat layer and then heat-dry it, with a drying temperature of 100 to 145°C being preferable, 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 dry completely. On the other hand, if the drying temperature exceeds 145°C, the film may be overheated, causing it to become brittle or shrink, resulting in poor processability. In particular, it is especially preferable to first evaporate the solvent at a relatively low temperature of 80°C to 110°C immediately after application, and then dry it at 120°C or higher, as this yields a uniform film. In addition to drying, applying an additional heat treatment in the lowest possible temperature range is also more effective in promoting the formation of the anchor coat layer.

[0083] [Protective layer on a permanent thin film (D)] In the present invention, a protective layer (D) may be provided on the inorganic thin film layer which is the gas barrier layer. The inorganic thin film layer made of a metal oxide layer is not a completely dense film, but has minute defects scattered throughout. By coating the metal oxide layer with a specific protective layer resin composition described later to form a protective layer, the resin in the protective layer resin composition penetrates into the defects in the metal oxide layer, and as a result the barrier properties of the gas barrier layer are stabilized. In addition, by using a material that also has gas barrier properties for the protective layer itself, the gas barrier performance of the laminated film is also improved.

[0084] In this invention, the amount of protective layer (D) attached is 0.10 to 0.40 (g / m²). 2It is preferable to have the protective layer uniformly controlled during coating, resulting in a film with fewer coating inconsistencies and defects. Furthermore, the cohesive force of the protective layer (D) itself is improved, and the adhesion between the inorganic thin film layer and the protective layer becomes stronger. The amount of protective layer attached is preferably 0.13 (g / m²). 2 ) or more, more preferably 0.16 (g / m³) 2 ) or more, more preferably 0.19 (g / m³) 2 ) or more, preferably 0.37 (g / m³) 2 ) or less, more preferably 0.34 (g / m³) 2 ) or less, more preferably 0.31 (g / m³) 2 ) or less. The amount of protective layer (D) attached is 0.400 (g / m²). 2 When the thickness exceeds 0.10 (g / m²), the gas barrier properties improve, but the cohesive force within the protective layer becomes insufficient, and the uniformity of the protective layer also decreases, which may result in unevenness or defects in the appearance of the coating, or insufficient gas barrier properties and adhesion. On the other hand, when the thickness of the protective layer (D) exceeds 0.10 (g / m²), 2 If the value is less than ), sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0085] As the resin composition used for the protective layer (D) formed on the surface of the inorganic thin film layer of the present invention, resins such as polyvinyl alcohol-based, urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins can be used, and curing agents such as epoxy-based, isocyanate-based, melamine-based, and silanol-based resins may also be added.

[0086] The coating method for the protective layer resin composition is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0087] When forming the protective layer (D), it is preferable to apply the protective layer resin composition and then heat-dry it, with a preferred drying temperature of 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C. If the drying temperature is below 100°C, the protective layer may not dry sufficiently, or the film formation of the protective layer may not proceed, reducing its cohesive strength and water-resistant adhesion, which may result in reduced barrier properties and tear resistance. On the other hand, if the drying temperature exceeds 160°C, the film may be overheated, making it brittle, reducing its puncture strength, or shrinking, which may worsen its processability. It is particularly preferable to first evaporate the solvent at a relatively low temperature of 90°C to 110°C immediately after application, and then dry the protective film at 130°C or higher, as this yields a uniform and transparent film. In addition to drying, applying an additional heat treatment in the lowest possible temperature range is also more effective in promoting the formation of the protective layer.

[0088] [Other films] In the present invention, other films besides the base film mainly composed of polyolefin resin may be used, as long as the monomaterial ratio to the packaging material described later is satisfied. Other films used in the present invention include, for example, films obtained by melt-extruding plastic and, if necessary, stretching in the longitudinal and / or widthwise directions, cooling, and heat-setting. Examples of plastics include polyamides represented by nylon 4-6, nylon 6, nylon 6-6, nylon 12, etc., polyesters represented by polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, etc., as well as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, fully aromatic polyamide, polyamide-imide, polyimide, polyetherimide, polysulfone, polystyrene, polylactic acid, and the like.

[0089] Other films in this invention can be of any thickness depending on the desired purpose, such as mechanical strength and transparency. While not particularly limited, a thickness of 5 to 250 μm is generally recommended, and 10 to 60 μm is preferable when used as a packaging material. However, consideration must be given to the monomaterial ratio of the packaging material, as described later.

[0090] Furthermore, the other films in this invention may be laminated films of one or more types of plastic films. In the case of laminated films, 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.

[0091] [Heat-sealable resin layer] The packaging material of the present invention requires a laminate with a heat-sealable resin layer. The heat-sealable resin layer is generally formed by laminating a thermoplastic polymer by extrusion lamination or dry lamination, but a film with the heat-sealable resin layer co-extruded or coated can also be prepared. The thermoplastic polymer forming the heat-sealable resin layer can be any polymer that exhibits sufficient adhesion, but polyolefin-based polyethylene resins such as HDPE, LDPE, and LLDPE, polypropylene resin, ethylene-vinyl acetate copolymer, ethylene-α-olefin random copolymer, and ionomer resin can be used. Among these, LLDPE or polypropylene resin are particularly preferred due to their high versatility from the viewpoints of durability, seal strength, cost, and monomaterialization. The thickness of the heat-sealable resin layer is preferably 5 to 100 μm, more preferably 10 to 95 μm, and more preferably 15 to 90 μm. A thickness thinner than 5 μm may result in insufficient seal strength and a lack of rigidity, making it difficult to handle. On the other hand, if the thickness exceeds 100 μm, the material becomes too stiff, reducing its handling properties as a bag, and requiring higher temperatures for sealing, which may cause heat wrinkles in the outer base film. Furthermore, the price may also increase.

[0092] [Adhesive layer] The adhesive layer used in this invention can be any general-purpose laminating adhesive. For example, solvent-free, water-based, or heat-melt adhesives mainly composed of poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, or casein can be used. Among these, urethane or polyester adhesives are preferred considering heat resistance and flexibility to follow dimensional changes of each substrate. The adhesive layer can be applied by methods such as direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fontein coating, or other methods, and the coating amount after drying is 1 to 8 g / m² to achieve sufficient adhesion. 2 Preferred. More preferably 2-7 g / m 2 More preferably 3-6 g / m 2 The coating amount is 1 g / m². 2 If the amount is less than 8 g / m², it becomes difficult to bond the entire surface, and the adhesive strength decreases. 2 Beyond this point, complete curing of the film takes longer, unreacted material is more likely to remain, and the adhesive strength decreases.

[0093] [Print layer] Furthermore, the packaging material of the present invention may have at least one printed layer laminated between or outside the base film layer and the heat-sealable resin layer.

[0094] Water-based and solvent-based resin-containing printing inks are preferably used as the printing ink for forming the printed layer. Examples of resins used in the printing ink 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, defoaming agents, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printed layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying, and infrared drying can be used.

[0095] [Characteristics of packaging materials] The packaging material of the present invention can take any conceivable laminated configuration, but as mentioned above, from the viewpoint of improving toughness and gas barrier performance, a laminate in which a film with a gas barrier layer is laminated is sandwiched between a base film without a gas barrier layer and a thermoplastic copolymer having a heat-sealable resin layer is one preferred configuration. In this case, an advantage is that by laminating the printed layer on the surface base film, it becomes unnecessary to print on the film with the gas barrier layer. Other preferred configurations include laminating with a white base film or heat-sealable resin layer to improve opacity, or laminating with an ultraviolet-cut film for light shielding.

[0096] In the packaging material of the present invention, at least one base film peeled off from the packaging material was measured by a thermomechanical analyzer. It is necessary that the heat elongation at 130°C be 6% or less in both the MD direction and the TD direction. This ensures the heat resistance required when used as a packaging body. For example, the finish is good when heat-sealing at high temperatures of 130°C or higher, the seal strength is stable, and the packaging body can be made with minimal dimensional and appearance changes when subjected to harsh moist heat treatments such as boiling at 95°C or high-temperature retorting at 130°C. The heat elongation at 130°C in the MD direction and the TD direction is preferably 5.5% or less, more preferably 5.0% or less, and even more preferably 4.5% or less, with a lower limit of 0% being preferable. If the heat elongation at 130°C is outside the above range, the heat resistance of the packaging body will decrease, which may result in poor appearance during sealing or moist heat treatment. In the present invention, the heat elongation is a value measured by a thermomechanical analyzer (TMA), and is described in more detail by the method in the examples. The TMA method allows for the quantitative determination of dimensional changes due to thermal load under a certain tension. Furthermore, since the tension and heat quantities can be arbitrarily set to simulate different processing conditions, it can serve as an indicator for observing behavior similar to actual processing.

[0097] In the present invention, in order to keep the heat elongation of the base film peeled from the packaging material within the above range, it is preferable to use a base film in which the heat elongation at 130°C is 10% or less in both the MD direction and the TD direction. Furthermore, the heat elongation can be reduced by subjecting the base film to a post-heat treatment. As means of heat treatment, the base film can be annealed in a drying oven, or heat can be applied in the inorganic thin film layer formation process or the anchor coat layer / protective layer coating process described above. In this case, it is preferable that the surface temperature of the film be 65°C or higher when heated, more preferably 70°C or higher, and even more preferably 75°C or higher. However, if the film temperature is 90°C or higher, expansion and contraction will increase, which may lead to a decrease in quality such as wrinkles, so the upper limit of heat application is 90°C.

[0098] The packaging material of the present invention has an oxygen permeability of 60 ml / m² under conditions of 23°C × 65% RH. 2 A gas barrier pressure of d·MPa or less is preferable for exhibiting good gas barrier properties. Furthermore, by providing a barrier layer on each film, a pressure of 50 ml / m² is preferable. 2 • d·MPa or less, more preferably 40 ml / m² 2 It can be set to d·MPa or less. Oxygen permeability of 60 ml / m³ 2 Above d·MPa, it becomes difficult to meet the requirements for applications demanding high gas barrier properties. On the other hand, if the oxygen permeability is 0.5 ml / m³ in all cases... 2 If the oxygen permeability is less than d·MPa, although the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, and the amount transferred to the contents may increase relatively, which is undesirable. The preferred lower limit for oxygen permeability is 0.5 ml / m³. 2 It is d·MPa or higher.

[0099] The packaging material of the present invention has an oxygen permeability of 60 ml / m² under conditions of 23°C × 65% RH after boiling at 95°C × 30 minutes. 2 A gas barrier pressure of d·MPa or less is preferable for exhibiting good gas barrier properties. Furthermore, by providing a barrier layer on each film, a pressure of 50 ml / m² is preferable. 2 • d·MPa or less, more preferably 40 ml / m² 2 It can be set to d·MPa or less. Oxygen permeability of 60 ml / m³ 2 Above d·MPa, it becomes difficult to meet the requirements for applications demanding high gas barrier properties. On the other hand, if the oxygen permeability is 0.5 ml / m³ in all cases... 2 If the oxygen permeability is less than d·MPa, although the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, and the amount transferred to the contents may increase relatively, which is undesirable. The preferred lower limit for oxygen permeability is 0.5 ml / m³. 2 It is d·MPa or higher.

[0100] The packaging materials of the present invention all exhibit a water vapor transmission rate of 5.0 g / m² under conditions of 40°C × 90% RH. 2A value of d or less is preferable in terms of exhibiting good gas barrier properties. Furthermore, by providing a barrier layer on each film, a value of 4.0 g / m² is preferable. 2 • d or less, more preferably 3.0 g / m 2 It can be less than or equal to d. Water vapor transmission rate of 5.0 g / m³ 2 If the value exceeds d, it becomes difficult to meet the requirements for applications that demand high gas barrier properties. On the other hand, if the water vapor transmission rate is 0.1 g / m³ 2 If the value is less than 0.1 g / m³, while the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, which may relatively increase the amount transferred to the contents, so this is undesirable. The preferred lower limit for water vapor permeability is 0.1 g / m³. 2 It is d or higher.

[0101] The packaging materials of the present invention all exhibit a water vapor transmission rate of 5.0 g / m² under conditions of 40°C × 90% RH after boiling at 95°C × 30 minutes. 2 A value of d or less is preferable in terms of exhibiting good gas barrier properties. Furthermore, by providing a barrier layer on each film, a value of 4.0 g / m² is preferable. 2 • d or less, more preferably 3.0 g / m 2 It can be less than or equal to d. Water vapor transmission rate of 5.0 g / m³ 2 If the value exceeds d, it becomes difficult to meet the requirements for applications that demand high gas barrier properties. On the other hand, if the water vapor transmission rate is 0.1 g / m³ 2 If the value is less than 0.1 g / m³, while the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, which may relatively increase the amount transferred to the contents, so this is undesirable. The preferred lower limit for water vapor permeability is 0.1 g / m³. 2 It is d or higher.

[0102] It is preferable that the heat seal strength of the heat-seal layer resin layers of the packaging material of the present invention is 15 N / 15 mm or more when heat-sealed at a temperature of 160°C, a seal bar pressure of 0.2 MPa, and a sealing time of 2 seconds. If the heat seal strength is less than 15 N / 15 mm, the sealed portion will easily peel off, limiting its use as a packaging bag, such as making it unsuitable for applications with large contents. A heat seal strength of 16 N / 15 mm or more is preferable, and 17 N / 15 mm or more is more preferable.

[0103] As an evaluation criterion for monomaterialization in the packaging material of the present invention, when the ratio of the thickness of the polyolefin-based material to the total thickness of each film and adhesive is calculated as the monomaterial (monomate) ratio, it is preferable that the monomate ratio is 70% or more. More preferably, it is 80% or more, and even more preferably, 90% or more. By setting the monomate ratio within this range, a packaging material structure that is easy to recycle can be made. If the monomate ratio is less than 70%, recycling may become difficult due to foreign matter from other materials. As mentioned above, it is preferable to use polypropylene resin as the polyolefin resin constituting the base film, but using polypropylene resin for the heat-sealable resin layer as well can result in a more easily recyclable structure. If all the polyolefin materials used are polypropylene resin, an even more easily recyclable structure can be achieved.

[0104] In the packaging material of the present invention, the total thickness of each film and adhesive is preferably 20 to 140 μm. More preferably 25 to 135 μm, and even more preferably 30 to 130 μm. By setting the total thickness of the packaging material within this range, it is possible to create a package that exhibits the necessary physical properties such as toughness and barrier performance. If the total thickness is less than 20 μm, the bag will not have sufficient toughness, and there is a risk that the bag will tear or get punctured. On the other hand, if the total thickness exceeds 140 μm, it will become too stiff and difficult to handle, and it will also lead to an increase in the cost of the package, which is not economically desirable.

[0105] As described above, the packaging material of the present invention possesses excellent heat resistance, toughness, and barrier properties, as well as superior visibility, making it suitable for use in various types of packaging. Examples of packaging applications include boiling or retort sterilization, frozen food applications, vacuum packaging, and microwave heating applications.

[0106] The form of the packaging using the packaging material of the present invention is not particularly limited and can take various forms. Examples of packaging forms include three-sided and four-sided pouches, standing pouches, spout pouches, and the like.

[0107] The contents to be filled into the packaging bag using the packaging material of the present invention are not particularly limited, and the contents may be liquids, powders, or gels. Furthermore, the contents may be food or non-food items. [Examples]

[0108] 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 performed using the following measurement methods.

[0109] (1) Thickness of various films Measurements were taken using a dial gauge in accordance with JIS K7130-1999 Method A.

[0110] (2) Composition and thickness of the inorganic thin film layer (B) The film thickness composition of the laminated films (after thin film lamination) obtained in the examples and comparative examples was measured using a fluorescent X-ray analyzer (Rigaku Corporation's "supermini200") according to a pre-prepared calibration curve. The excitation X-ray tube conditions were 50kV and 4.0mA.

[0111] (3) Amount of adhesion of coating layer (A), anchor coat layer (C), and protective layer (D) In each example and comparative example, the laminated films obtained by laminating a predetermined coating layer (A), anchor coat layer (C), and protective layer (D) onto a base film were used as samples. A 100 mm x 100 mm test piece was cut from this sample, and the coating layer was wiped with either water, ethanol, or acetone. The amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0112] (4) Method for evaluating the appearance after processing In each example and comparative example, the film appearance was visually evaluated after lamination of the coating layer (A), inorganic thin film layer (B), anchor coat layer (C), and protective layer (D). ○: No defects occurred, good condition. ×: One of the following defects occurs: wrinkles, uneven coating, or paint repellency.

[0113] (5) Method for evaluating the rate of dimensional change after processing In each example and comparative example, the length A in the film width direction before lamination of the coating layer (A), inorganic thin film layer (B), anchor coat layer (C), and protective layer (D) was measured, and the length B in the film width direction after lamination (for example, after lamination of the protective layer if the anchor, inorganic thin film layer, and protective layer are all laminated) was measured. The value X obtained from the following formula was evaluated as the dimensional change rate after processing. Dimensional change rate after processing X = (AB) / A × 100

[0114] [Production of packaging materials] (6) Preparation of evaluation packaging materials When using a single base film, a polyurethane adhesive (TM569 / cat10L manufactured by Toyo Morton Co., Ltd.) was applied to the base film described in the Examples and Comparative Examples to a thickness of 3 μm after drying at 80°C. Then, an unstretched polypropylene film, linear low-density polyethylene film, or PET sealant film, described later, was dry-laminated on a metal roll heated to 60°C as a heat-sealable resin, and aged at 40°C for 2 days (48 hours) to obtain a laminated structure for evaluation. On the other hand, when two base films were used, a polyurethane adhesive (TM569 / cat10L manufactured by Toyo Morton Co., Ltd.) was applied to the base film described in the Examples and Comparative Examples so that the thickness after drying at 80°C was 3 μm. Then, the other base film was dry-laminated on a metal roll heated to 60°C to form a winding roll. The same adhesive was applied to this roll so that the thickness after drying at 80°C was 3 μm. Then, an unstretched polypropylene film, linear low-density polyethylene film, or PET sealant film, described later, was dry-laminated on a metal roll heated to 60°C as a heat-sealable resin, and aging was performed at 40°C for 2 days (48 hours) to obtain a packaging material for evaluation.

[0115] (7) Method for evaluating the oxygen permeability of packaging materials The oxygen permeability of the packaging material prepared in (6) above was measured in accordance with JIS-K7126 Method B using an oxygen permeability measuring device (MOCON Corporation's "OX-TRAN(registered trademark) 2 / 22") in an atmosphere of 23°C and 65% RH humidity. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side of the packaging material to the heat-sealable resin layer side. On the other hand, the packaging material prepared in (6) above was subjected to a boiling treatment by holding it in 95°C hot water for 30 minutes, and then dried at 40°C for 1 day (24 hours). The oxygen permeability (after boiling) of the resulting moist heat-treated packaging material was measured in the same manner as above.

[0116] (8) Method for evaluating the water vapor permeability of packaging materials For the packaging material prepared in (6) above, the water vapor transmission rate was measured in accordance with JIS-K7129 Method B using a water vapor transmission rate measuring device (MOCON "PERMATRAN-W 3 / 33MG") in an atmosphere of 40°C and 90% RH. The water vapor transmission rate was measured in the direction in which water vapor permeates from the base film side of the packaging material toward the heat-sealable resin side. On the other hand, the packaging material prepared in (5) above was subjected to a boiling treatment by holding it in 95°C hot water for 30 minutes, and then dried at 40°C for 1 day (24 hours). The water vapor transmission rate (after boiling) of the resulting moist heat-treated packaging material was measured in the same manner as above.

[0117] (9) Method for evaluating the heat seal strength of packaging materials The packaging material prepared in (6) above was subjected to heat seal strength measurement in accordance with JIS Z 1707. The specific procedure is as follows: The heat seal surfaces of the samples were bonded together using a heat sealer. The heat sealing conditions were: upper bar temperature 160°C, lower bar temperature 30°C, pressure 0.2 MPa, and time 2 seconds. The bonded samples were cut to have a seal width of 15 mm. The peel strength was measured using a universal tensile testing machine "DSS-100" (manufactured by Shimadzu Corporation) at a tensile speed of 200 mm / min. The peel strength is expressed as strength per 15 mm (N / 15 mm). For the evaluation of the seal appearance, a relative evaluation was performed, with ○ indicating a seal without wrinkles, △ indicating wrinkles in some areas, and × indicating wrinkles throughout the entire surface.

[0118] (10) Heat elongation rate (%) of the base film peeled off the packaging material The thermal elongation was measured for the base film peeled off from the packaging material prepared in (6) above. The thermal elongation was determined by TMA measurement using a thermomechanical analyzer (Shimadzu Corporation "TMA-60"). The thermal elongation in the MD direction was measured by cutting the packaging material of the examples and comparative examples to a width of 80 mm in the MD direction and 30 mm in the TD direction. Samples were then prepared by cutting strips of the base film from the base film, which had been peeled apart between the adhesive layers, to a width of 30 mm in the MD direction and 4 mm in the TD direction. The measurement conditions were a chuck distance of 10 mm, a measurement temperature range of 30°C to 150°C, a heating rate of 20°C / min, and a tensile load of 0.39 N applied to the sample piece. The thermal elongation was determined from the chuck distance (mm) before heating and the chuck distance (mm) when the temperature reached 130°C. To determine the thermal elongation in the TD direction, samples were prepared by cutting the packaging material of the examples and comparative examples to a width of 80 mm in the MD direction and 30 mm in the TD direction. From the base film, which was peeled apart between the adhesive layers, strips of the base film were further cut to a width of 30 mm in the TD direction and 4 mm in the MD direction. The measurement conditions were a chuck distance of 10 mm, a measurement temperature range of 30°C to 150°C, a heating rate of 20°C / min, and a tensile load of 0.39 N applied to the sample piece. The thermal elongation was determined from the chuck distance (mm) before heating and the chuck distance (mm) when 130°C was reached. The heating elongation rate (S130) when the temperature reached 130°C was calculated using the following formula. (S130) = (Distance between chucks when heated to 130°C - Distance between chucks before heating) / Distance between chucks before heating × 100

[0119] (11) Evaluation criteria for monomaterialization: monomaterial ratio For the packaging materials prepared in (6) above, the monomaterial ratio was calculated as the ratio of the thickness of the olefin-based material to the total thickness of each film and adhesive, as an evaluation criterion for monomaterialization.

[0120] (12) Criteria for evaluating visibility and range suitability Regarding the packaging materials prepared in (6) above, the evaluation criteria for visibility and range suitability were as follows: those with a transparent packaging body and no aluminum foil or aluminum vapor deposition used in the barrier layer were marked with a circle (○).

[0121] (13) Percentage change in dimensions after boiling (%) The packaging material prepared in (6) above was scored with 150 mm lines drawn in the MD direction, TD direction, at an angle of -45° relative to the MD direction (direction A), and at an angle of +45° relative to the MD direction (direction B). This was followed by a boiling treatment in 95°C hot water for 30 minutes, and then drying at 40°C for 1 day (24 hours). The length of the scored lines (mm) of the resulting moist heat-treated packaging material was measured again, and the dimensional change before and after treatment was calculated using the following formula. Dimensional change rate after boiling = (Dimensions after boiling - 150) / 150 × 100 Table 5 shows the values ​​with the highest dimensional change rates among the MD direction, TD direction, A direction, and B direction.

[0122] The base films used in this example and comparative example are listed below. These were used in Examples 1-16 and Comparative Examples 1-7, and are shown in Table 5. [Preparation of base film] Tables 1 to 4 show the details of the polypropylene resin raw materials used in the production of polyolefin-based films OPP-1 to 7, the film manufacturing conditions, and the raw material mixing ratios.

[0123] [Table 1]

[0124] [Table 2]

[0125] [Table 3]

[0126] [Table 4]

[0127] (OPP-1) The base layer (A) consisted of 30.0% by weight of polypropylene homopolymer PP-2 shown in Table 1 and 70.0% by weight of polypropylene homopolymer PP-3 shown in Table 1. Furthermore, the surface layer (B) used a mixture of PP-3, a polypropylene homopolymer shown in Table 1, at a ratio of 96.4% by weight, and masterbatch A, shown in Table 2, at a ratio of 3.6% by weight. For the surface layer (C), a mixture of PP-3, a polypropylene homopolymer shown in Table 1, and masterbatch A, shown in Table 2, was used in a ratio of 94.0% by weight and 6.0% by weight. The base layer (A) was produced using a 45 mmφ extruder, the surface layer (B) using a 25 mmφ extruder, and the surface layer (C) using a 20 mmφ extruder. The raw resin was melted at 250°C in each case, and co-extruded into a sheet from a T-die. After cooling and solidifying so that the surface layer (B) was in contact with a cooling roll at 30°C, the film was stretched 4.5 times in the longitudinal direction (MD) at 125°C. Next, in a tenter, both ends in the width direction (TD) of the film were clamped with clips, preheated to 173°C, stretched 8.2 times in the width direction (TD) at 164°C, and then heat-set at 171°C while relaxing by 6.7% in the width direction (TD). The film-forming conditions at this time are referred to as film-forming condition a. Details of these film-forming conditions are shown in Table 3. Thus, a biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained. The surface of the biaxially oriented polypropylene film surface layer (B) was corona treated using a corona treatment machine manufactured by Softal Corona & Plasma GmbH at an applied current of 0.75 A, and then wound up with a winder. The thickness of the resulting film was 20 μm (the thickness of the surface layer (B) / substrate layer (A) / surface layer (C) was 1.0 μm / 18.0 μm / 1.0 μm). The details of this configuration are shown in Table 4.

[0128] (OPP-2) For the base layer (A), the polypropylene homopolymer PP-1 shown in Table 1 was used. Furthermore, the surface layer (B) used a mixture of PP-3, a polypropylene homopolymer shown in Table 1, at a ratio of 96.4% by weight, and masterbatch A, shown in Table 2, at a ratio of 3.6% by weight. For the surface layer (C), a mixture of PP-3, a polypropylene homopolymer shown in Table 1, and masterbatch A, shown in Table 2, was used in a ratio of 94.0% by weight and 6.0% by weight. The base layer (A) was produced using a 45 mmφ extruder, the surface layer (B) using a 25 mmφ extruder, and the surface layer (C) using a 20 mmφ extruder. The raw resin was melted at 250°C in each case, and co-extruded into a sheet from a T-die. After cooling and solidifying so that the surface layer (B) was in contact with a cooling roll at 30°C, the film was stretched 4.5 times in the longitudinal direction (MD) at 135°C. Next, in a tenter, both ends in the width direction (TD) of the film were clamped with clips, preheated to 168°C, stretched 8.2 times in the width direction (TD) at 155°C, and then heat-set at 165°C while relaxing by 6.7% in the width direction (TD). The film-forming conditions at this time were designated as film-forming condition b. Details of these film-forming conditions are shown in Table 3. Thus, a biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained. The surface of the biaxially oriented polypropylene film surface layer (B) was corona treated using a corona treatment machine manufactured by Softal Corona & Plasma GmbH at an applied current of 0.75 A, and then wound up with a winder. The thickness of the resulting film was 20 μm (the thickness of the surface layer (B) / substrate layer (A) / surface layer (C) was 1.0 μm / 18.0 μm / 1.0 μm). The details of this configuration are shown in Table 4.

[0129] (OPP-3) The base layer (A) used a mixture of 27.0% by weight of polypropylene homopolymer PP-2 shown in Table 1, 70.0% by weight of polypropylene homopolymer PP-3 shown in Table 1, and 3% by weight of [PE-1: ethylene homopolymer "SLH218" manufactured by Braskem, MFR: 2.3 g / 10 min, melting point: 126 °C, bio-based: 84%, density: 0.916 g / cm³]. Furthermore, the surface layer (B) used a mixture of PP-3, a polypropylene homopolymer shown in Table 1, at a ratio of 96.4% by weight, and masterbatch A, shown in Table 2, at a ratio of 3.6% by weight. For the surface layer (C), a mixture of PP-3, a polypropylene homopolymer shown in Table 1, and masterbatch A, shown in Table 2, was used in a ratio of 94.0% by weight and 6.0% by weight. The base layer (A) was produced using a 45 mmφ extruder, the surface layer (B) using a 25 mmφ extruder, and the surface layer (C) using a 20 mmφ extruder. The raw resin was melted at 250°C in each case, and co-extruded into a sheet from a T-die. After cooling and solidifying so that the surface layer (B) was in contact with a cooling roll at 30°C, the film was stretched 4.5 times in the longitudinal direction (MD) at 125°C. Next, in a tenter, both ends in the width direction (TD) of the film were clamped with clips, preheated to 173°C, stretched 8.2 times in the width direction (TD) at 164°C, and then heat-set at 171°C while relaxing by 6.7% in the width direction (TD). The film-forming conditions at this time are referred to as film-forming condition a. Details of these film-forming conditions are shown in Table 3. Thus, a biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained. The surface of the biaxially oriented polypropylene film surface layer (B) was corona treated using a corona treatment machine manufactured by Softal Corona & Plasma GmbH at an applied current of 0.75 A, and then wound up with a winder. The thickness of the resulting film was 20 μm (the thickness of the surface layer (B) / substrate layer (A) / surface layer (C) was 1.0 μm / 18.0 μm / 1.0 μm). The details of this configuration are shown in Table 4.

[0130] (OPP-4) For the base layer (A), a mixture of PP-2, a polypropylene homopolymer shown in Table 1, in a ratio of 30.0% by weight, and PP-3, a polypropylene homopolymer shown in Table 1, in a ratio of 70.0% by weight, was used. Furthermore, the surface layer (B) used a mixture consisting of 45.0% by weight of the polypropylene homopolymer PP-3 shown in Table 1, 52.0% by weight of the propylene-ethylene copolymer shown in Table 1, and 3.0% by weight of the masterbatch B shown in Table 2. For the surface layer (C), a mixture of PP-3, a polypropylene homopolymer shown in Table 1, and masterbatch B, shown in Table 2, was used in a ratio of 96.0% by weight and 4.0% by weight. The base layer (A) was produced using a 45 mmφ extruder, the surface layer (B) using a 25 mmφ extruder, and the surface layer (C) using a 20 mmφ extruder. The raw resin was melted at 250°C in each case, and co-extruded into a sheet from a T-die. After cooling and solidifying so that the surface layer (B) was in contact with a cooling roll at 40°C, the film was stretched 4.5 times in the longitudinal direction (MD) at 125°C. Next, in a tenter, both ends in the width direction (TD) of the film were clamped with clips, preheated to 167°C, stretched 8.2 times in the width direction (TD) at 163°C, and then heat-set at 169°C while relaxing by 6.7% in the width direction (TD). The film-forming conditions at this time are referred to as film-forming condition a. Details of these film-forming conditions are shown in Table 3. Thus, a biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained. The surface of the biaxially oriented polypropylene film surface layer (B) was corona treated using a corona treatment machine manufactured by Softal Corona and Plasma GmbH at an applied current of 0.75 A, and then wound up with a winder. The thickness of the resulting film was 20 μm (the thicknesses of the surface layer (B) / substrate layer (A) / surface layer (C) were 1.3 μm / 17.7 μm / 1.0 μm). Details of this configuration are shown in Table 4.

[0131] (OPP-5) A biaxially oriented polypropylene film with the structure of surface layer (B) / substrate layer (A) / surface layer (C) was obtained in the same manner as in (OPP-1), except that the base layer (A) was extruded as a single layer in a 45 mmφ extruder into a sheet, the surface layer (B) was extruded using a 25 mmφ extruder, and the surface layer (C) was extruded using a 20 mmφ extruder and laminated. The thickness of the obtained film was 20 μm (the thicknesses of surface layer (B) / substrate layer (A) / surface layer (C) were 2.0 μm / 21.0 μm / 2.0 μm). Details of this structure are shown in Table 4.

[0132] (OPP-6) A biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained using the same method as in (OPP-1), except that the stretching conditions were changed to condition d as shown in Table 3. The thickness of the obtained film was 20 μm (the thicknesses of surface layer (B) / substrate layer (A) / surface layer (C) were 2.0 μm / 21.0 μm / 2.0 μm). Details of this configuration are shown in Table 4.

[0133] (OPP-7) A biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained using the same method as in (OPP-1), except that the stretching conditions were changed to condition e as shown in Table 3. The thickness of the obtained film was 20 μm (the thicknesses of surface layer (B) / substrate layer (A) / surface layer (C) were 2.0 μm / 21.0 μm / 2.0 μm). Details of this configuration are shown in Table 4.

[0134] (Other base films) (PET) Biaxially oriented polyester film (Toyobo E5100 - 12μm) (NY) Biaxially oriented polyamide film (Toyobo N1100 - 15 μm) (Vaporized PET) 12μm thick transparent vapor-deposited polyester film (Toyobo "VE707")

[0135] (Coating layer (A)) The details of the coating liquid used to form the coating layer (A) in this example and comparative example are described below. These were used in Examples 1-16 and Comparative Examples 1-7, and are shown in Table 5.

[0136] [Polyvinyl alcohol resin (a)] 90 parts by mass of purified water were mixed with 10 parts by mass of fully saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: G Polymer OKS8049Q, (saponification degree 99.0% or higher, average degree of polymerization 450)). The mixture was heated to 80°C while stirring, and then stirred for approximately 1 hour. After that, it was cooled to room temperature to obtain a nearly transparent polyvinyl alcohol solution (PVA solution) with a solid content of 10%.

[0137] [Inorganic layered compound dispersion (b)] Five parts by mass of montmorillonite (trade name: Kunipia F, manufactured by Kunimine Industries Co., Ltd.), an inorganic layered compound, were added to 95 parts by mass of purified water while stirring, and thoroughly dispersed using a homogenizer at a setting of 1500 rpm. The mixture was then incubated at 23°C for one day to obtain a dispersion of the inorganic layered compound with a solid content of 5%.

[0138] [Coating liquid 1 to be used for coating layer 1] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 15.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (a) 30.00% by mass Inorganic layered compound dispersion (b) 40.00% by mass

[0139] [Coating liquid 2 to be used for coating layer 2] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 15.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (a) 70.00% by mass

[0140] [Coating liquid 3 to be used for the coating layer 3] The following materials were mixed in the mass ratio shown below and stirred for at least 30 minutes to dissolve. Then, undissolved material was removed using a filter with a nominal filtration accuracy of 50 μm to prepare a coating solution (resin composition for the coating layer). Ion-exchanged water 37.50% by mass Polyvinylidene chloride resin (c) 62.50% by mass (Saran latex L557 manufactured by Asahi Kasei Chemicals, solids content ratio 48%)

[0141] (Coating the film with a coating solution (lamination of coating layers)) The coating solution prepared above 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 amount of coating layer adhered at this time was 0.30 g / m². 2 Subsequently, a heat treatment was performed at 40°C for 2 days (48 hours). In this manner, a laminated film having one of the coating layers 1 to 3 was prepared.

[0142] (Inorganic thin film layer (B)) The following describes the method for preparing the inorganic thin film layer (A) used in each example and comparative example. The layers used in Examples 1-16 and Comparative Examples 1-7 are shown in Table 5.

[0143] (Formation of inorganic thin film layer 1) As inorganic thin film layer 1, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the anchor coat layer by electron beam deposition. Particulate SiO2 (99.9% purity) and A12O3 (99.9% purity) of approximately 3mm to 5mm in size were used as the deposition source. The thickness of the inorganic thin film layer (SiO2 / A12O3 composite oxide layer) in the resulting film (inorganic thin film layer / coating layer-containing film) was 13nm. The composition of this composite oxide layer was SiO2 / A12O3 (mass ratio) = 70 / 30.

[0144] (Formation of inorganic thin film layer 2) As the inorganic thin film layer 2, silicon oxide was deposited on the anchor coat layer. Using a small vacuum deposition apparatus (ULVAC KIKO, Inc., VWR-400 / ERH), 10 -3 After reducing the pressure to below Pa, silicon dioxide was placed in a Nilaco B-110 evaporation source from the bottom of the substrate and heated to evaporate it, forming a silicon dioxide film with a thickness of 30 nm on the film.

[0145] (Formation of inorganic thin film layer 3) As the inorganic thin film layer 3, metallic aluminum was deposited on the anchor coat layer. Using a small vacuum deposition apparatus (ULVAC KIKO, Inc., VWR-400 / ERH), 10 -3After reducing the pressure to below Pa, 99.9% pure aluminum foil was placed in a Nilaco CF-305W evaporation source from below the substrate, and metallic aluminum was heated and evaporated to form a 30 nm thick metallic aluminum film on the film.

[0146] (Anchor coat layer (C)) The following describes the method for preparing the anchor coat layer (C) used in each example and comparative example. [Polyester resin (a)] As the polyester component, polyester polyol (DIC Corporation's "DF-COAT GEC-004C": solid content 30%) was used.

[0147] [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.

[0148] [Silane coupling agent (c)] N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silane coupling agent.

[0149] [Urethane resin (d)] As the urethane resin, a polyester urethane resin dispersion (DIC Corporation's "Hydran® AP-201"; solid content 23%) was used.

[0150] [Urethane resin (e)] As the urethane resin, a polyester urethane resin dispersion (Mitsui Chemicals, Ltd.'s "Takelac® WPB531"; solid content 30%) was used.

[0151] [Coating liquid 1 for anchor coat layer 1] A solution (15% by mass) of silane coupling agent (c) dissolved in acetone and isocyanate (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 PGM), and polyester resin (a) was added to obtain the target coating solution 1. The mixing ratio is shown below. Polyester resin (a) 10.62% by mass Isocyanate (b) 4.07% by mass Silane coupling agent (c) *Acetone dilution 1.73% by mass Methyl ethyl ketone 69.55% by mass PGM 14.03% by mass

[0152] [Coating liquid 2 for anchor coat layer 2] The following coating agents were mixed to create coating solution 2. Water 43.91% by mass Isopropanol 30.00% by mass Urethane resin (d) 26.09% by mass

[0153] [Coating liquid 3 for anchor coat layer 3] The following coating agents were mixed to create coating solution 3. Water 46.00% by mass Isopropanol 30.00% by mass Urethane resin (e) 24.00% by mass

[0154] (Coating the film with a coating solution (lamination of anchor coat layers)) The coating layer was applied to the corona-treated surface of the substrate film using coating solutions 1 to 3 by gravure roll coating. After pre-drying at 95°C for 4 seconds, it was fully dried at 115°C for 4 seconds to obtain the anchor coat layer. The adhesion amount of the anchor coat layer at this time was 0.40 g / m². 2 Subsequently, a post-heat treatment was performed at 40°C for 4 days (96 hours) to obtain the desired laminated film. (Protective layer (D)) Using the same coating solution as used when forming the aforementioned coating layer 1, the coating was applied to the inorganic thin film layer of the substrate film by gravure roll coating, and dried in a 120°C dry oven for 10 seconds to obtain protective layer 1. The amount of protective layer adhered at this time was 0.30 g / m². 2 The film was then subjected to a post-heat treatment at 40°C for 2 days (48 hours). In this manner, a laminated film with a protective layer was fabricated.

[0155] In this manner, packaging materials were prepared that included a coating layer, an anchor coat layer, an inorganic thin film layer, or a protective layer on each film, and further contained a heat-sealable resin.

[0156] In each example and comparative example, the respective packaging materials were bonded together using the dry lamination method with the aforementioned adhesive to produce packaging materials with the configurations shown in Table 5. The heat-sealable resin layer used was one of the following:

[0157] (Heat-sealable resin) (CPP1) Unoriented polypropylene film with a thickness of 30 μm (Toyobo Co., Ltd. "P1128") (CPP2) Unoriented polypropylene film with a thickness of 70 μm (Toyobo Co., Ltd. "P1146") (LL2) Linear low-density polyethylene film with a thickness of 40 μm (Toyobo "L4102") The composition of the prepared packaging is shown in Table 5. Various evaluations were also conducted on the obtained packaging. The results are shown in Table 5.

[0158] [Table 5A]

[0159] [Table 5B] [Industrial applicability]

[0160] The present invention significantly improves gas barrier performance by laminating a predetermined barrier layer, tailored to the required performance, onto a polyolefin-based substrate film in the form of a packaging material. Furthermore, it ensures heat resistance to withstand processing and sealing, and ultimately contributes to monomaterialization while maintaining high sealing performance by laminating with a sealant composed of olefin-based components. Moreover, since the packaging material of the present invention can be manufactured easily with fewer processing steps, it is excellent in both economic efficiency and production stability, and can provide a gas barrier packaging body with homogeneous properties.

Claims

1. A packaging material comprising at least one laminated base film, which is a stretched film mainly composed of a polyolefin resin, with a gas barrier layer laminated onto it, and a heat-sealable polyolefin resin layer, wherein the gas barrier layer is an inorganic oxide thin film layer. An anchor coat layer is laminated between the base film and the gas barrier layer, or a protective layer is laminated on top of the gas barrier layer. The monomaterial ratio, which is the ratio of the thickness of polyolefin-based material to the total thickness of the packaging material, is 70% or more. A laminated substrate film obtained by peeling a heat-sealable polyolefin resin layer from the aforementioned packaging material was measured using a thermomechanical analyzer with a sample width of 4 mm, a tensile load of 0.39 N, and a heating rate of 20 °C / min within a measurement temperature range of 30 °C to 150 °C. The heated elongation at 130 °C was 6% or less in both the MD and TD directions, and the oxygen permeability of the aforementioned packaging material under a 23 °C × 65% RH environment was 60 ml / m². ２ A packaging material characterized by having a density of d·MPa or less.

2. The packaging material according to claim 1, characterized in that the heat-sealable resin layer is made of a polyolefin resin mainly composed of polypropylene or polyethylene resin.

3. The packaging material according to claim 1, characterized in that it includes two or more gas barrier layers.

4. The packaging material according to claim 1, characterized in that the gas barrier layer is an inorganic oxide thin film layer made of one of aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide.

5. The packaging material according to claim 1, characterized in that two or more base films, which are stretched films, are used.

6. The packaging material according to claim 1, characterized in that the polyolefin resin constituting the base film contains 1% by weight or more and 25% by weight or less of plant-derived polyethylene resin.

7. A packaging material according to any one of claims 1 to 6, characterized in that it is used for boiling or retorting.

8. A packaging material according to any one of claims 1 to 6, characterized in that it is used for microwave heating.

9. A packaging bag made using the packaging material described in any one of claims 1 to 6.

10. A package in which an object to be packaged is packaged using the packaging material described in any one of claims 1 to 6.

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