Laminated film

Abstract

To provide a laminated film excellent in gas barrier properties after sterilization treatment, holding sufficient toughness as a polyamide film and also excellent from an aspect of productivity or an environmental load.SOLUTION: A laminated film in which an inorganic thin film layer and a protective layer are laminated in this order on a polyamide base film, the laminated film satisfying the following requirements (a) to (d): (a) When the oxygen permeability of a laminate structure obtained by bonding the laminated film to the heat-sealable resin layer under measurement conditions of 23 °C * 65% RH is defined as A, and the oxygen permeability of the structure after treatment with hot water at 95 °C for 30 minutes under measurement conditions of 23 °C * 65% RH is defined as B, the change rate X of the oxygen permeability before and after the hot water treatment satisfies the following: X (%) = (B / A) * 100 ≤ 200 (b) The polyamide base film and the inorganic thin film layer are adjacent to each other. (c) The number of pinholes after subjecting a laminate structure obtained by laminating the laminated film with a heat-sealable resin to Gelboflex treatment at 1 °C * 1,000 times is 5 or less. (d) The protection layer of the laminated film has a hardness of 200 to 350N / mm2 and a water-contact angle of 60 degrees or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated film used in the packaging field of foods, pharmaceuticals, industrial products, etc. More specifically, it relates to a convenient packaging material that is excellent in gas barrier properties, heat sterilization treatability, and toughness. [Background technology]

[0002] Packaging materials used for food, pharmaceuticals, etc. are required to have gas barrier properties, i.e., the ability to block gases such as oxygen and water vapor, in order to prevent oxidation of proteins and fats, preserve flavor and freshness, and maintain the efficacy of pharmaceuticals.

[0003] Conventionally, in food applications that require blocking various gases such as water vapor and oxygen, gas barrier laminates have generally been used, in which a metal thin film made of aluminum or the like or an inorganic thin film made of an inorganic oxide such as silicon oxide or aluminum oxide is formed on the surface of a plastic substrate film. In particular, those formed with a thin film (inorganic thin film layer) of an inorganic oxide such as silicon oxide, aluminum oxide, or a mixture thereof are widely used because they are transparent and allow the contents to be confirmed.

[0004] However, the aforementioned inorganic thin film layer is susceptible to external physical and chemical damage, resulting in problems such as reduced barrier performance and adhesiveness. In particular, during thermal sterilization processes such as boiling and retorting, which are methods for long-term food storage, significant deterioration in gas barrier performance has been observed due to film expansion and contraction and damage from hot water. Common methods for addressing this performance decline include laminating a coating layer between the inorganic thin film layer and the substrate, or laminating a protective layer on the inorganic thin film layer. Regarding the former, for example, it has been reported that providing a crosslinked coating layer made of an oxazoline group-containing polymer between the substrate and the inorganic thin film layer improves adhesion and water resistance (see, for example, Patent Document 1). Regarding the latter, for example, a method has been proposed in which a water-soluble polymer, an inorganic layered compound, and a metal alkoxide or its hydrolyzate are coated on the inorganic thin film layer, and then a highly crosslinked structure of the inorganic material containing the inorganic layered compound and the water-soluble polymer is formed on the inorganic thin film by a sol-gel method (see, for example, Patent Document 2). These methods protect the vapor-deposited layer from external loads such as hot water and shrinkage stress, and are therefore expected to maintain gas barrier performance even after hot water treatment.

[0005] However, while the lamination of coating layers with a highly cross-linked structure is very effective in achieving adhesive properties and water resistance, problems can arise when attempting to recover and re-melt the non-product portions of the film for reuse. Specifically, aggregates from the coating layer can become foreign matter and contaminate the recycled product, and in some cases cause process problems (such as film breakage) during film re-production or re-melting. The inability to recover and reuse the film is a significant concern not only in terms of cost, but also due to the impact on the environment caused by the increase in waste plastic, which has become a problem in recent years.

[0006] On the other hand, highly cross-linked protective layers, such as the sol-gel coating mentioned above, have poor flexibility, and depending on their thickness, there is concern that they may reduce the film's toughness, such as its resistance to pinholes due to bending. Furthermore, obtaining a protective layer with a highly cross-linked structure requires drying and solidification at high temperatures. This may embrittle the base film itself, reducing its resistance to pinholes due to bending and its resistance to punctures. Furthermore, there is a risk that the film may shrink during high-temperature drying, resulting in quality problems such as wrinkles.

[0007] Under these circumstances, there has been a demand for an improvement that enables a resin layer to be formed on an inorganic thin film layer by a coating method that does not involve a sol-gel reaction, i.e., a coating method that uses a resin as the main component and only involves a partial crosslinking reaction during coating. An example of a gas barrier laminate that has been improved in this way is a laminate in which an inorganic thin film is coated with a metaxylylene group-containing polyurethane (for example, Patent Document 3).

[0008] When using polyester film as the substrate, it is possible to produce a gas barrier film with good gas barrier properties and hot water resistance using the methods described above. However, for applications where preventing tearing or holes in the bag is important, a polyamide film, which has a strong structure, is required as the substrate. However, when using polyamide film as the substrate, even with the above-mentioned method, there are concerns that the hygroscopic nature of polyamide film means that water can easily penetrate between the layers under hot water conditions, and the film can expand and contract significantly, resulting in a decrease in barrier properties after hot water treatment. Another issue is that the toughness, which is originally the greatest advantage of polyamide film, is significantly reduced by the thermal load during organic and inorganic coating processing. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5560708 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-43182 [Patent Document 3] Patent No. 4524463 Summary of the Invention [Problem to be solved by the invention]

[0010] The above patent documents did not provide a film that could simultaneously maintain the gas barrier properties after hot water treatment, retain the toughness of films such as polyamide films, and have excellent recoverability and reusability, which are advantageous in terms of cost and the environment.

[0011] The present invention has been made in view of the above problems in the prior art. That is, an object of the present invention is to provide a laminated film that has excellent gas barrier properties after sterilization treatment, retains sufficient toughness as a polyamide film, and is also excellent in terms of productivity and environmental impact. [Means for solving the problem]

[0012] The present inventors have discovered that by providing a predetermined inorganic thin film layer and a protective layer using predetermined materials and processing conditions, it is possible to provide an environmentally friendly and convenient laminate film for packaging materials that can maintain gas barrier performance even after hot water treatment and also retain the high toughness of the base film, thereby leading to the completion of the present invention.

[0013] That is, the present invention comprises the following configurations. 1. A laminated film comprising a polyamide substrate film on which an inorganic thin film layer and a protective layer are laminated in this order, the laminated film being characterized by satisfying the following requirements (a) to (d): (a) When the oxygen permeability of a laminate structure obtained by bonding the laminate film to a heat-sealable resin layer under measurement conditions of 23°C x 65% RH is defined as A, and the oxygen permeability of the structure under measurement conditions of 23°C x 65% RH after treating the structure with hot water at 95°C for 30 minutes is defined as B, the rate of change X in oxygen permeability before and after hot water treatment satisfies the following: X(%)=(B / A)×100≦200 (b) The polyamide substrate film and the inorganic thin film layer are adjacent to each other. (c) The laminate structure obtained by laminating the laminated film with a heat-sealable resin has 5 or less pinholes after being subjected to a Gelboflex treatment at 1°C x 1000 times. (d) the surface hardness of the protective layer surface of the laminated film is 200 to 350 N / mm 2 And the water contact angle must be 60 degrees or more. 2. The laminate film according to 1, wherein the inorganic thin film layer is an inorganic thin film layer made of any one of aluminum, aluminum oxide, silicon oxide, and a composite oxide of silicon oxide and aluminum oxide. 3. The laminated film according to 1. or 2., wherein the protective layer is a protective layer containing a polyester resin having a urethane skeleton. 4. The laminated film according to any one of 1. to 3., which is used for heating in a microwave oven. 5. A packaging material characterized by using a film according to any one of 1. to 4. laminated thereto. 6. A packaging bag made using the packaging material described in 5. 7. A package in which the packaged item is packaged using the packaging material described in 5. above. 8. A package in which the packaged item is packaged using the packaging bag described in 6. [Effects of the Invention]

[0014] By using this technology, the inventors can provide a laminated film for packaging materials that can maintain gas barrier performance even after hot water treatment and retain the high toughness of the base film, making it environmentally friendly and highly convenient. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below. [Base film] In the present invention, a biaxially stretched polyamide film is used as the substrate film. The film is preferably a biaxially stretched polyamide film in which a functional layer (referred to as layer B) is laminated on at least one side of a substrate layer (referred to as layer A). Each layer will be described in detail below.

[0016] [Base material layer (A layer)] The substrate layer (Layer A) preferably comprises a polyamide resin composition containing at least (a) 99 to 70 mass% of polyamide 6 resin and (b) 1 to 30 mass% of a resin other than the polyamide 6 resin. When the substrate layer (Layer A) contains 70 mass% or more of polyamide 6 resin, a biaxially oriented polyamide film with excellent mechanical strength, such as impact strength, can be obtained. When the substrate layer (Layer A) contains 1 to 20 mass% of resin (b), which has the effect of imparting flexibility, a biaxially oriented polyamide film with excellent flex pinhole resistance can be obtained.

[0017] The base layer (A layer) can further improve its pinhole resistance due to bending by adding a specific polyamide resin containing a biomass-derived raw material as resin (b).

[0018] The amount of resin (b) contained in the base layer (layer A) is preferably as small as possible. The reason for this is that resin (b), which provides flexibility, is expected to have a lower melting point and lower thermal stability than polyamide 6. Therefore, from the perspective of suppressing the generation of foreign matter during production, it is desirable to add as little resin as possible. The preferred amount of resin (b) is 2.5 to 17.5%, and more preferably 5 to 15%.

[0019] The polyamide 6 used in the base layer (layer A) is usually produced by ring-opening polymerization of ε-caprolactam. The polyamide 6 obtained by ring-opening polymerization is usually subjected to hot water to remove the lactam monomer, then dried and melt-extruded in an extruder.

[0020] The relative viscosity of polyamide 6 is preferably 1.8 to 4.5, and more preferably 2.6 to 3.2. If the relative viscosity is less than 1.8, the impact strength of the film will be insufficient. If the relative viscosity is more than 4.5, the load on the extruder will increase, making it difficult to obtain an unstretched film before stretching.

[0021] The resin (b) contained in the base layer (layer A) preferably has a glass transition temperature (Tg) of -30°C or lower. By using a resin with a glass transition temperature of -30°C or lower, excellent pinhole resistance can be achieved even at room temperature to in a frozen environment. Among these, thermoplastic elastomers such as polyester elastomers, polyamide elastomers, polyolefin elastomers, polystyrene elastomers, polyurethane elastomers, and polyvinyl chloride elastomers, ionomer polymers, aliphatic polyester resins such as polybutylene succinate and polybutylene succinate adipate, and aromatic aliphatic polyester resins such as polybutylene adipate terephthalate are preferred because of their flexible properties.

[0022] The base layer (layer A) may contain various additives such as other thermoplastic resins, lubricants, heat stabilizers, antioxidants, antistatic agents, anti-fogging agents, ultraviolet absorbers, dyes, pigments, etc., as needed.

[0023] [Functional Layer (Layer B)] The functional layer (B layer) is preferably a layer containing 70% by mass or more of polyamide 6 resin. By containing 70% by mass or more of polyamide 6 resin, a polyamide film having excellent mechanical strength such as impact strength can be obtained. As the polyamide 6 resin, the same polyamide 6 resin as that used in the base layer (A layer) can be used. The functional layer (B layer) can contain various additives such as other thermoplastic resins, lubricants, heat stabilizers, antioxidants, antistatic agents, anti-fogging agents, UV absorbers, dyes, pigments, etc. depending on the function to be imparted to the functional layer (B layer). When the functional layer (B layer) is used on the outside of a packaging bag, it needs to be resistant to abrasion and pinholes, so it is not preferable to include soft resins such as polyamide elastomers or polyolefin elastomers or substances that generate a large number of voids.

[0024] The functional layer (layer B) preferably contains fine particles or an organic lubricant as a lubricant to improve the film's slipperiness. Improving the slipperiness improves the film's handling properties and reduces the risk of packaging bags breaking due to friction.

[0025] The fine particles can be appropriately selected from inorganic fine particles such as silica, kaolin, zeolite, etc., and polymeric organic fine particles such as acrylic and polystyrene fine particles, etc. From the viewpoints of transparency and lubricity, it is preferable to use silica fine particles.

[0026] The average particle size of the fine particles is preferably 0.5 to 5.0 μm, more preferably 1.0 to 3.0 μm. If the average particle size is less than 0.5 μm, a large amount of addition is required to obtain good slip properties. On the other hand, if the average particle size exceeds 5.0 μm, the surface roughness of the film tends to become too large, resulting in poor appearance.

[0027] When using the silica fine particles, the pore volume of the silica is preferably in the range of 0.5 to 2.0 ml / g, and more preferably 0.8 to 1.6 ml / g. If the pore volume is less than 0.5 ml / g, voids are likely to occur, resulting in poor film transparency. If the pore volume exceeds 2.0 ml / g, the fine particles tend to be less likely to form protrusions on the surface.

[0028] The organic lubricant may contain a fatty acid amide and / or a fatty acid bisamide, such as erucic acid amide, stearic acid amide, ethylene bisstearic acid amide, ethylene bisbehenic acid amide, or ethylene bisoleic acid amide. The content of fatty acid amide and / or fatty acid bisamide added to the functional layer (B layer) is preferably 0.01 to 0.40% by mass, more preferably 0.05 to 0.30% by mass. If the content of fatty acid amide and / or fatty acid bisamide is less than the above range, slip properties tend to be poor. On the other hand, if it exceeds the above range, wettability tends to be poor.

[0029] To improve the slipperiness of the film, polyamide resins other than polyamide 6, such as polyamide MXD6 resin, polyamide 11, polyamide 12 resin, polyamide 66 resin, polyamide 6·12 copolymer resin, and polyamide 6·66 copolymer resin, can be added to the functional layer (layer B). Polyamide MXD6 resin is particularly preferred, and it is preferable to add it in an amount of 1 to 10% by mass. If it is less than 1% by mass, the effect of improving the slipperiness of the film is small. If it is more than 10% by mass, the effect of improving the slipperiness of the film becomes saturated. Polyamide MXD6 resin is produced by polycondensation of metaxylylenediamine and adipic acid. The relative viscosity of polyamide MXD6 is preferably 1.8 to 4.5, and more preferably 2.0 to 3.2. If the relative viscosity is less than 1.8 or more than 4.5, it may be difficult to knead it with the polyamide resin in the extruder.

[0030] In addition, to improve adhesion, polyamide resins other than polyamide 6 can be added to the functional layer (layer B). In this case, copolymer polyamide resins such as polyamide 6·12 copolymer resin and polyamide 6·66 copolymer resin are preferred.

[0031] The base layer (A layer) and functional layer (B layer) of the polyamide film of the present invention may contain an antioxidant. Phenol-based antioxidants are preferred as antioxidants. The phenol-based antioxidant is preferably a fully hindered phenolic compound or a partially hindered phenolic compound. The inclusion of the phenol-based antioxidant improves the film-forming operability of the biaxially oriented polyamide film. In particular, when recycled film is used as a raw material, thermal degradation of the resin is likely to occur, which can lead to operational problems in film-forming and increased production costs. In contrast, the inclusion of an antioxidant inhibits thermal degradation of the resin and improves operability.

[0032] Subsidiary materials and additives such as lubricants and antioxidants can be added to the base layer (A layer) and functional layer (B layer) of the biaxially stretched polyamide film of the present invention during resin polymerization or melt extrusion in an extruder. Alternatively, a high-concentration masterbatch can be prepared and added to the polyamide resin during film production. Such known methods can be used.

[0033] The thickness of the biaxially stretched polyamide film of the present invention is not particularly limited, but when used as a packaging material, it is usually 100 μm or less, and a thickness of 5 to 50 μm is generally used, and a thickness of 5 to 30 μm is particularly used.

[0034] In the thickness configuration of each layer of the biaxially stretched polyamide film of the present invention, if the thickness of the functional layer (layer B) accounts for a large proportion of the total film thickness, the flex pinhole resistance will decrease. Therefore, in the present invention, the thickness of the base layer (layer A) is preferably 50 to 93%, particularly 60 to 93%, of the total thickness of the base layer (layer A) and the functional layer (layer B). The layer structure of the base film is not particularly limited, but a layer B / layer A / layer B structure is preferred from the viewpoint of imparting the required functions to the surface and interior of the film, respectively.

[0035] When a polyamide resin at least partly derived from biomass is used in the biaxially stretched polyamide film of the present invention, the above radiocarbon (C14 The content of biomass-derived carbon measured by the FTIR (Fatalization Test) is preferably 1 to 15% of the total carbon in the polyamide film. Atmospheric carbon dioxide contains C 14 Since carbon dioxide is contained in the atmosphere at a constant rate (105.5pMC), plants that grow by absorbing carbon dioxide from the atmosphere, such as corn, contain 14 The carbon content is known to be about 105.5 pMC. 14 It is also known that almost no carbon atoms are contained in the resin. 14 By measuring the ratio of carbon derived from biomass, the ratio of carbon derived from biomass can be calculated.

[0036] The heat shrinkage of the film of the present invention at 160°C for 10 minutes is in the range of 0.6 to 3.0%, preferably 0.6 to 2.5%, in both the machine direction (hereinafter abbreviated as MD) and the width direction (hereinafter abbreviated as TD). If the heat shrinkage exceeds 3.0%, curling or shrinkage may occur when heat is applied in subsequent processes such as laminating an inorganic thin film layer, laminating a protective layer, laminating, or printing. Furthermore, the lamination strength with a heat-sealable resin may be weakened. Although it is possible to reduce the heat shrinkage to less than 0.6%, the film may become mechanically fragile. Furthermore, productivity may be reduced.

[0037] Since excellent impact resistance is a feature of biaxially oriented polyamide films, the impact strength of the biaxially oriented polyamide film of the present invention is preferably 0.7 J / 15 μm or more, and more preferably 0.9 J / 15 μm or more.

[0038] The puncture strength of the biaxially stretched polyamide film of the present invention is preferably 0.67 N / μm or more, and more preferably 0.77 N / μm or more. By setting the puncture strength to 0.67 N / μm or more, even when filled with solid contents, it is possible to prevent the bag from being punctured by the contents and from being perforated by external factors during transportation.

[0039] The haze value of the biaxially stretched polyamide film of the present invention is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less. A low haze value means good transparency and gloss, so when used in packaging bags, beautiful printing is possible and commercial value is increased. Since the haze value increases when fine particles are added to improve the slipperiness of the film, the haze value can be reduced by adding fine particles only to the surface functional layer (layer B).

[0040] [Method for producing biaxially oriented polyamide film] The method for producing the biaxially stretched polyamide film of the present invention will be described below. First, the raw material resin is melt-extruded using an extruder, extruded through a T-die into a film, and cast onto a cooling roll for cooling to obtain an unstretched film. In the present invention, a co-extrusion method using a feed block or multi-manifold is preferred to obtain an unstretched film in which a base layer (A layer) and a functional layer (B layer) are laminated. In addition to the co-extrusion method, dry lamination, extrusion lamination, etc. can also be selected. When laminating by the co-extrusion method, it is desirable to use a polyamide resin composition used for the base layer (A layer) and the functional layer (B layer) such that the difference in melt viscosity between the base layer (A layer) and the functional layer (B layer) is small. The melting temperature of the resin is preferably 220 to 350° C. If it is lower than this, unmelted matter may occur, resulting in defects and other poor appearance, while if it exceeds this, deterioration of the resin may be observed, resulting in a decrease in molecular weight and a deterioration in appearance. The die temperature is preferably 250 to 350°C. The cooling roll temperature is preferably -30 to 80°C, and more preferably 0 to 50°C. To obtain an unstretched film by casting the film-like melt extruded from a T-die onto a rotating cooling drum and cooling it, methods such as an air knife method and an electrostatic adhesion method in which a static charge is applied are preferably used, with the latter being particularly preferred.

[0041] It is also preferable to cool the surface of the cast unstretched film opposite the cooling roll. For example, it is preferable to use a method in which a cooling liquid in a tank is brought into contact with the surface of the unstretched film opposite the cooling roll, a method in which a vaporizing liquid is applied with a spray nozzle, or a method in which a high-velocity fluid is sprayed onto the surface to cool the film. The unstretched film thus obtained is stretched biaxially to obtain the biaxially stretched polyamide film of the present invention.

[0042] The stretching method may be either a simultaneous biaxial stretching method or a sequential biaxial stretching method, with the sequential biaxial stretching method being preferred since it can increase the film production speed and is advantageous in terms of production costs. In either case, the MD stretching method can be one-stage stretching or multi-stage stretching such as two-stage stretching. As will be described later, multi-stage MD stretching such as two-stage stretching is preferred over one-stage stretching in terms of physical properties and uniformity of physical properties in the MD and TD directions (isotropy). In the sequential biaxial stretching method, stretching in the MD direction is preferably performed by roll stretching.

[0043] The lower limit of the MD stretching temperature is preferably 50°C, more preferably 55°C, and even more preferably 60°C. If the temperature is less than 50°C, the resin does not soften and stretching may be difficult. The upper limit of the MD stretching temperature is preferably 120°C, more preferably 115°C, and even more preferably 110°C. If the temperature exceeds 120°C, the resin may become too soft and stable stretching may not be possible.

[0044] The lower limit of the stretching ratio in the MD direction (when stretching is performed in multiple stages, the total stretching ratio obtained by multiplying each stretching ratio) is preferably 2.2, more preferably 2.5, and even more preferably 2.8. If it is less than 2.2, the thickness accuracy in the MD direction decreases, and the crystallinity becomes too low, which may reduce the impact strength. The upper limit of the stretching ratio in the MD direction is preferably 5.0, more preferably 4.5, and most preferably 4.0. If the stretching ratio exceeds 5.0, subsequent stretching may become difficult.

[0045] When stretching in the MD direction is performed in multiple stages, the above-mentioned stretching is possible in each stretching, but the stretching ratios must be adjusted so that the product of all MD stretching ratios is 5.0 or less. For example, in the case of two-stage stretching, the first stage stretching is preferably 1.5 to 2.1 times, and the second stage stretching is preferably 1.5 to 2.0 times.

[0046] The film stretched in the MD direction is stretched in the TD direction using a tenter, heat-set, and then subjected to a relaxation treatment (also called a relaxation treatment). The lower limit of the TD stretching temperature is preferably 50° C., more preferably 55° C., and even more preferably 60° C. If the temperature is less than 50° C., the resin does not soften, making stretching difficult. The upper limit of the TD stretching temperature is preferably 190° C., more preferably 185° C., and even more preferably 180° C. If the temperature exceeds 190° C., crystallization may occur, making stretching difficult.

[0047] The lower limit of the stretching ratio in the TD direction (when stretching is performed in multiple stages, the total stretching ratio obtained by multiplying each stretching ratio) is preferably 2.8, more preferably 3.2, even more preferably 3.5, and particularly preferably 3.8. If it is less than 2.8, the thickness accuracy in the TD direction decreases, and the crystallinity becomes too low, which may reduce the impact strength. The upper limit of the stretching ratio in the TD direction is preferably 5.5 times, more preferably 5.0 times, even more preferably 4.7 times, particularly preferably 4.5 times, and most preferably 4.3 times. If the stretching ratio exceeds 5.5 times, productivity may decrease significantly.

[0048] The selection of the heat setting temperature is an important factor in the present invention. As the heat setting temperature increases, the crystallization and orientation relaxation of the film progress, improving the impact strength and reducing the heat shrinkage rate. On the other hand, if the heat setting temperature is low, the crystallization and orientation relaxation are insufficient, making it impossible to sufficiently reduce the heat shrinkage rate. Moreover, if the heat setting temperature is too high, the resin deteriorates and the film rapidly loses its toughness, such as its impact strength.

[0049] The lower limit of the heat setting temperature is preferably 210° C., more preferably 212° C. If the heat setting temperature is too low, the heat shrinkage rate becomes too large, which tends to deteriorate the appearance after lamination and reduce the laminate strength. The upper limit of the heat setting temperature is preferably 220° C., more preferably 218° C. If the heat setting temperature is too high, the impact strength tends to decrease.

[0050] The heat setting time is preferably 0.5 to 20 seconds, and more preferably 1 to 15 seconds. The heat setting time can be adjusted appropriately by balancing the heat setting temperature and the air speed in the heat setting zone. If the heat setting conditions are too weak, crystallization and orientation relaxation will be insufficient, causing the above problems. If the heat setting conditions are too strong, the film toughness will decrease.

[0051] Relaxation treatment after heat setting is effective in controlling the heat shrinkage rate. The temperature for relaxation treatment can be selected within the range from the heat setting temperature to the Tg of the resin, but is preferably from the heat setting temperature -10°C to Tg +10°C. If the relaxation temperature is too high, the shrinkage rate will be too fast, which is undesirable and can cause distortion. Conversely, if the relaxation temperature is too low, relaxation treatment will not occur and the film will simply become loose, which will not reduce the heat shrinkage rate and will result in poor dimensional stability.

[0052] The lower limit of the relaxation rate in the relaxation treatment is preferably 0.5%, more preferably 1%. If it is less than 0.5%, the heat shrinkage rate may not be reduced sufficiently. The upper limit of the relaxation rate is preferably 20%, more preferably 15%, and even more preferably 10%. If it exceeds 20%, sagging occurs in the tenter, which may make production difficult.

[0053] Furthermore, the biaxially stretched polyamide film of the present invention can be subjected to heat treatment or humidity conditioning treatment to improve dimensional stability depending on the application, and can also be subjected to corona treatment or flame treatment to improve the adhesiveness of the film surface.

[0054] [Inorganic thin film layer (C layer)] In the present invention, the film has an inorganic thin film layer (layer C) adjacent to the surface of the base layer as a gas barrier layer. Because the base film on which the thin film is laminated does not include a separate layer such as a coating layer, it is easily recyclable, and unused portions of the film can be reused. Furthermore, if the coating layer itself has poor hot water resistance, the inorganic thin film layer may be physically damaged due to a decrease in adhesive strength at the interface between the film and the inorganic thin film or deformation of the coating layer, resulting in a deterioration in gas barrier properties. Therefore, from the perspective of performance, it is preferable that no coating layer is laminated. The inorganic thin film layer (layer C) is a thin film made of a metal or inorganic oxide. There are no particular limitations on the material forming the inorganic thin film layer as long as it can be formed into a thin film. However, from the viewpoint of gas barrier properties, preferred examples include metals such as aluminum, and inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and mixtures of silicon oxide and aluminum oxide. In particular, complex oxides of silicon oxide and aluminum oxide are preferred in terms of achieving both flexibility and density of the thin film layer. In this complex oxide, the mixing ratio of silicon oxide to aluminum oxide is preferably in the range of 20 to 70 mass% Al in terms of the mass ratio of the metal components. If the Al concentration is less than 20 mass%, the water vapor barrier properties may be reduced. On the other hand, if the Al concentration exceeds 70 mass%, the inorganic thin film layer tends to become hard, which may result in destruction of the film during secondary processing such as printing or lamination, resulting in reduced gas barrier properties. Here, silicon oxide refers to various silicon oxides such as SiO and SiO2 or mixtures thereof, and aluminum oxide refers to various aluminum oxides such as AlO and Al2O3 or mixtures thereof.

[0055] The inorganic thin film layer (C layer) has a thickness of usually 1 to 100 nm, preferably 5 to 95 nm, and more preferably 7 to 90 nm. If the inorganic thin film layer (C layer) has a thickness of less than 1 nm, it may be difficult to obtain satisfactory gas barrier properties. On the other hand, even if the inorganic thin film layer (C layer) is excessively thick, exceeding 100 nm, the corresponding improvement in gas barrier properties cannot be obtained and is actually disadvantageous in terms of flex resistance and production costs.

[0056] The method for forming the inorganic thin film layer (C layer) is not particularly limited, and any known vapor deposition method may be appropriately employed, such as physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD). A typical method for forming the inorganic thin film layer (C layer) will be described below, taking silicon oxide / aluminum oxide-based thin films 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 source. These deposition sources are typically particles, and the particle size is preferably such that the pressure during deposition does not change, with a preferred particle diameter being 1 mm to 5 mm. Heating methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating can be used. Furthermore, reactive vapor deposition using reactive gases such as oxygen, nitrogen, hydrogen, argon, carbon dioxide, and water vapor, or ozone addition or ion-assisted deposition can also be employed. Furthermore, the film formation conditions can be changed as desired by applying a bias to the deposition target (the laminated film to be deposited), heating or cooling the deposition target, etc. The deposition materials, reactive gases, bias, heating or cooling of the deposition target, etc. can be changed in the same way when using the sputtering method or the CVD method.

[0057] [Protective layer on an indestructible thin film (D)] In the present invention, a protective layer (D) is provided on the inorganic thin film layer, which serves as a gas barrier layer. The inorganic thin film layer, consisting of a metal or metallized layer, is not a completely dense film but has minute defects scattered throughout. By forming a protective layer by coating a specific resin composition for the protective layer (described below) on the metal oxide layer, the resin in the resin composition for the protective layer penetrates into the defects in the metal oxide layer, resulting in the effect of stabilizing the barrier properties of the gas barrier layer. In addition, by using a material with gas barrier properties for the protective layer itself, the gas barrier performance of the laminate film is also improved. Furthermore, the present inventors have discovered that laminating a protective layer can maintain good gas barrier performance even after hot water treatment, which led to the present invention.

[0058] The resin composition used for the protective layer formed on the surface of the inorganic thin film layer of the laminate film of the present invention is preferably a polyester resin having a urethane skeleton. The inclusion of a urethane skeleton is preferable because, in addition to the barrier performance and protective properties due to the high cohesiveness of the urethane bond itself, the polar group interacts with the inorganic thin film layer to improve adhesion, and the presence of an amorphous portion provides flexibility, thereby suppressing damage to the inorganic thin film layer even when the film expands or contracts due to hot water treatment.

[0059] Surface hardness is one of the physical properties that control the cohesion and flexibility of the protective layer (D). In the present invention, the surface hardness of the protective layer side is 200 to 350 N / mm 2 It is necessary that the range is 210 to 340 N / mm. 2 , and more preferably 220 to 330 N / mm 2 By setting the surface hardness within the above range, the protective layer can suppress damage to the inorganic thin film layer due to external loads such as hot water and bending. 2 If the surface hardness is less than 350 N / mm, the protective layer may swell in hot water, losing its protective properties and causing the vapor deposition layer to be damaged and peel off. 2 If the hardness is larger, the surface becomes hard and brittle, which may cause the film to be unable to follow the expansion and contraction of the film when exposed to hot water, resulting in a risk of deterioration in barrier performance. Furthermore, stress may be easily transmitted when bent, which may reduce toughness, such as pinhole resistance. To achieve the above-mentioned surface hardness range for the protective layer, it is preferable to blend a urethane resin (described below) and, if necessary, a crosslinking agent, etc., and achieve a coating amount within a predetermined range using the method for forming the protective layer (described below). Note that, in the method for measuring surface hardness (described below), care should be taken because the surface hardness value may change if the test force is changed.

[0060] In the present invention, the water contact angle of the protective layer surface is preferably within the range of 60 to 75 degrees. It is more preferably within the range of 62 to 73 degrees, and even more preferably within the range of 64 to 71 degrees. By setting the contact angle within this range, the protective layer becomes resistant to water, thereby reducing damage to the inorganic thin film layer during hot water treatment such as boiling. Furthermore, since the protective layer has a certain level of wettability, ink loss and other issues are unlikely to occur during printing, allowing for the deposition of a clear printed layer. If the contact angle is less than 60 degrees, the protective layer may swell in water, losing its protective properties or even peeling off. On the other hand, if the contact angle is greater than 75 degrees, the wettability is low, making it difficult for ink to be applied, resulting in reduced printability. Furthermore, there is a risk of reduced interlayer adhesion with the hydrophilic inorganic thin film layer.

[0061] In the present invention, in order to keep the barrier change rate after hot water treatment within a predetermined range, the amount of the protective layer applied is set to 0.10 g / m 2 It is preferable that the density is 0.10 to 0.60 g / m or more. 2 It is more preferable to set the coating weight to 0.12 g / m. This makes it easier to apply the coating uniformly, reducing coating unevenness and defects, while enhancing the protection of the inorganic thin film. In addition, the cohesive strength of the protective layer itself is improved, strengthening the adhesion between the inorganic thin film layer and the protective layer, and improving water resistance. The coating weight of the protective layer is preferably 0.12 g / m. 2 More preferably, 0.14 g / m 2 More preferably, 0.16 g / m 2 or more, preferably 0.58 g / m² or less, more preferably 0.56 g / m² or less 2 The protective layer has a coating weight of 0.60 g / m or less, and more preferably 0.54 g / m or less. 2 If the thickness of the protective layer exceeds 0.10 g / m, the cohesive force inside the protective layer may become insufficient, and adhesion may decrease. Furthermore, unevenness or defects may occur in the coating appearance, and gas barrier properties and adhesive properties may not be fully exhibited. Also, from the viewpoint of recyclability, a high adhesion amount is not desirable. On the other hand, if the thickness of the protective layer is 0.10 g / m, 2 If the thickness is less than 1000 nm, the film may be too thin and may not provide sufficient protection and interlayer adhesion.

[0062] (polyester resin) The polyester resin used in the present invention is produced by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The molecular weight of the polyester is not particularly limited as long as it can provide sufficient film toughness, coatability, and solvent solubility for use as a coating material, but the number average molecular weight is 1,000 to 50,000, more preferably 1,500 to 30,000. The functional group at the polyester end is also not particularly limited, and it may be an alcohol end, a carboxylic acid end, or both. However, when an isocyanate-based curing agent is used in combination, it is necessary to use a polyester polyol that is predominantly alcohol-terminated.

[0063] [Polyester glass transition temperature (Tg)] The Tg of the polyester used in the present invention must be 15°C or higher. If the temperature is lower than this, the resin will become tacky after the coating operation, making it more susceptible to blocking and making the winding operation after coating difficult. If the Tg is 15°C or lower, it will be difficult to prevent blocking even under conditions where the pressure near the winding core is high, even with the addition of an anti-blocking agent. The Tg temperature is more preferably 18°C ​​or higher, and even more preferably 25°C or higher.

[0064] The polyester used in the present invention is prepared by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. [Polycarboxylic acid component] The polycarboxylic acid component of the polyester used in the present invention is characterized by containing at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. The ortho-orientation improves solubility in solvents, enabling uniform coating on the substrate. A uniformly coated protective layer reduces variation in barrier performance. Furthermore, the ortho-orientation results in a film with excellent flexibility and improved interfacial adhesion, reducing damage to the substrate due to wet heat treatment. Examples of aromatic polycarboxylic acids or anhydrides thereof in which a carboxylic acid is substituted at the ortho-position include orthophthalic acid or anhydride, naphthalene 2,3-dicarboxylic acid or anhydride, naphthalene 1,2-dicarboxylic acid or anhydride, anthraquinone 2,3-dicarboxylic acid or anhydride, and 2,3-anthracene carboxylic acid or anhydride. These compounds may have a substituent at any carbon atom of the aromatic ring. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimide group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group. Furthermore, polyester polyols containing these compounds in an amount of 70 to 100 mol% relative to 100 mol% of the total polycarboxylic acid components are particularly preferred because they not only effectively improve barrier properties but also have excellent solvent solubility, which is essential for coating materials.

[0065] In the present invention, other polycarboxylic acid components may be copolymerized within the range that does not impair the effects of the invention. Specifically, examples of aliphatic polycarboxylic acids that can be used include succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; examples of unsaturated bond-containing polycarboxylic acids include maleic anhydride, maleic acid, and fumaric acid; examples of alicyclic polycarboxylic acids include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; and examples of aromatic polycarboxylic acids include terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, diphenic acid and its anhydride, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, and anhydrides or ester-forming derivatives of these dicarboxylic acids; and examples of polybasic acids that can be used alone or in mixtures of two or more thereof include p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalic acid, and diphenic acid are preferred from the viewpoint of organic solvent solubility and gas barrier properties.

[0066] [Polyhydric alcohol component] The polyhydric alcohol component of the polyester used in the present invention is not particularly limited as long as it can synthesize a polyester that exhibits gas barrier replenishing performance, but it is preferable for the polyhydric alcohol component to contain at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, and 1,3-bishydroxyethylbenzene. Among these, it is most preferable to use ethylene glycol as the main component, since it is presumed that the fewer the number of carbon atoms between oxygen atoms, the less flexible the molecular chain becomes and the more difficult oxygen permeates.

[0067] In the present invention, it is preferable to use the polyhydric alcohol component described above, but other polyhydric alcohol components may also be copolymerized as long as the effects of the present invention are not impaired. Specific examples of diols include 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of trihydric or higher alcohols include glycerol, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl)isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythritol. Polyesters containing glycerol and tris(2-hydroxyethyl)isocyanurate in combination are particularly preferred, as they have a moderately high crosslinking density due to their branched structure, resulting in good solubility in organic solvents and excellent barrier properties.

[0068] Examples of catalysts that can be used in the reaction to obtain the polyester of the present invention include tin-based catalysts such as monobutyltin oxide and dibutyltin oxide, titanium-based catalysts such as tetraisopropyltitanate and tetrabutyltitanate, and acid catalysts such as zirconia-based catalysts such as tetrabutylzirconate. It is preferable to use a combination of the above-mentioned titanium-based catalysts, such as tetraisopropyltitanate and tetrabutyltitanate, which have high activity in esterification reactions, with the above-mentioned zirconia catalyst. The amount of the catalyst used is 1 to 1,000 ppm, more preferably 10 to 100 ppm, based on the total mass of the reaction raw materials used. If the amount is less than 1 ppm, it is difficult to obtain the catalytic effect, while if it exceeds 1,000 ppm, problems such as inhibition of the urethanization reaction may occur when an isocyanate curing agent is used.

[0069] In the present invention, when a polyester resin is used as the main component of the coating agent that constitutes the protective layer, an isocyanate-based curing agent must be used to introduce a urethane skeleton. In this case, the coating layer becomes crosslinked, which has the advantage of improving moisture and heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use in boiled or retort packaging.

[0070] When the polyester has hydroxyl groups, the polyisocyanate compound used in the present invention reacts at least partially to form a urethane structure, thereby making the resin component highly polar and causing aggregation between polymer chains, thereby further enhancing the gas barrier function. Furthermore, when the resin of the coating material is a linear resin, crosslinking with a trivalent or higher polyisocyanate can impart heat resistance and abrasion resistance. The polyisocyanate compound used in the present invention may be a diisocyanate, a trivalent or higher polyisocyanate, a low-molecular-weight compound, or a high-molecular-weight compound, but it is preferable to contain an aromatic ring or an aliphatic ring as part of the skeleton from the viewpoint of improving the gas barrier function. Examples of isocyanates having an aromatic ring include toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; examples of isocyanates having an aliphatic ring include hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, isophorone diisocyanate, and norbornane diisocyanate, as well as trimers of these isocyanate compounds, and compounds containing terminal isocyanate groups obtained by reacting an excess amount of these isocyanate compounds with low-molecular-weight active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine, or high-molecular-weight active hydrogen compounds such as various polyester polyols, polyether polyols, and polyamides.

[0071] The protective layer used in the present invention may contain various crosslinking agents to improve the cohesive strength and heat- and moisture-resistant adhesion of the film, as long as the gas barrier properties are not impaired. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, and epoxy compounds. Among these, the incorporation of a silicon-based crosslinking agent can particularly improve the water-resistant adhesion to the inorganic thin film layer. From this perspective, silicon-based crosslinking agents are particularly preferred. Other crosslinking agents such as oxazoline compounds, carbodiimide compounds, and epoxy compounds may also be used in combination.

[0072] As the silicon-based crosslinking agent, a silane coupling agent is preferred from the viewpoint of crosslinking between inorganic and organic substances. Examples of the silane coupling agent include hydrolyzable alkoxysilane compounds, such as halogen-containing alkoxysilanes (chloro C2-4 alkyl tri C1-4 alkoxysilanes such as 2-chloroethyl trimethoxysilane, 2-chloroethyl triethoxysilane, 3-chloropropyl trimethoxysilane, 3-chloropropyl triethoxysilane, etc.), alkoxysilanes having an epoxy group (2-glycidyloxyethyl trimethoxysilane, 2-glycidyloxyethyl triethoxysilane, 3-glycidyloxypropyl triethoxysilane, etc.), and the like. trimethoxysilane, glycidyloxy C2-4 alkyltriC1-4 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 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc.], alkoxysilanes having an amino group [aminoC2-4 alkyltriC1-4 alkoxysilanes such as 2-aminoethyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc., aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, etc., 2-[N-(2-aminoethyl)amino] (2-aminoC2-4 alkyl)aminoC2-4 alkyltriC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, and 3-[N-(2-aminoethyl)amino]propyltriethoxysilane; (aminoC2-4 alkyl)aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane and 3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane;Alkoxysilanes having a mercapto group (mercapto C2-4 alkyltri C1-4 alkoxysilanes such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc., mercaptodi C2-4 alkyldi C1-4 alkoxysilanes such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc.), alkoxysilanes having a vinyl group (vinyltri C1-4 alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.), ethylene Examples include alkoxysilanes having a hydrophilically unsaturated bond group [(meth)acryloxyC2-4 alkyltriC1-4 alkoxysilanes such as 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane; and (meth)acryloxydiC2-4 alkyldiC1-4 alkoxysilanes such as 3-(meth)acryloxypropylmethyldimethoxysilane and 3-(meth)acryloxypropylmethyldiethoxysilane]. These silane coupling agents can be used alone or in combination. Of these silane coupling agents, silane coupling agents having an amino group are preferred.

[0073] The silane coupling agent or silicon-based crosslinking agent is preferably added to the protective layer in an amount of 0.25 to 3.00% by mass, more preferably 0.5 to 2.75% by mass, and even more preferably 0.75 to 2.50% by mass. The addition of the silane coupling agent promotes film hardening and improves cohesive strength, resulting in a film with excellent water-resistant adhesion. If the amount added exceeds 3.00% by mass, the film hardens and improves cohesive strength, but some unreacted portions may remain, potentially reducing interlayer adhesion. On the other hand, if the amount added is less than 0.25% by mass, sufficient cohesive strength may not be obtained.

[0074] The method for applying the resin composition for the protective layer is not particularly limited as long as it is a method that can apply the resin composition for the protective layer to the surface of a film to form a layer. For example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0075] When forming the protective layer (D), it is preferable to apply the protective layer resin composition and then heat-dry it. The drying temperature is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C. Drying temperatures below 100°C can result in insufficient drying of the protective layer, or the formation of the protective layer cannot proceed, resulting in reduced cohesive strength and water-resistant adhesion, which can result in reduced barrier properties and hand-tearability. On the other hand, drying temperatures above 160°C can result in excessive heat being applied to the film, making it brittle and reducing puncture strength, or shrinking and reducing processability. It is particularly preferable to first volatilize the solvent at a relatively low temperature of 90 to 120°C immediately after application, and then dry the protective layer at 130°C or higher, as this results in a uniform and transparent film. In addition to drying, additional heat treatment at as low a temperature as possible can be even more effective in promoting the formation of the protective layer.

[0076] [Other films] In the present invention, other films may be laminated. The other films used in the present invention are, for example, films obtained by melt-extruding plastics and, if necessary, stretching them in the longitudinal and / or transverse directions, cooling, and heat setting. Examples of plastics include polyamides such as nylon 4-6, nylon 6, nylon 6-6, and nylon 12, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, as well as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, wholly aromatic polyamides, polyamideimides, polyimides, polyetherimides, polysulfones, polystyrenes, and polylactic acids.

[0077] The other films used in the present invention may have any thickness depending on the desired purpose, such as mechanical strength, transparency, etc. Although not particularly limited, a thickness of 5 to 250 μm is usually recommended, and when used as a packaging material, a thickness of 10 to 60 μm is desirable.

[0078] The other film in the present invention may be a laminated film of one or more types of plastic films. When a laminated film is used, the type of laminate, the number of layers, the lamination method, etc. are not particularly limited, and can be arbitrarily selected from known methods depending on the purpose.

[0079] [Adhesive layer] The adhesive layer used in the present invention can be a general-purpose laminating adhesive. Examples include solvent-free, water-based, and hot-melt adhesives based on poly(ester)urethane, polyester, polyamide, polyamine, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, and casein. Among these, adhesives obtained by crosslinking polyurethane, polyester, and polyamine resins are preferred from the viewpoints of heat resistance, flexibility to accommodate dimensional changes in each substrate, and improved gas barrier properties of the adhesive itself. However, caution is required because if the film becomes too hard due to crosslinking, there is a risk of reduced barrier performance after bending. It is also effective to add inorganic substances such as particles to improve barrier performance. The adhesive layer can be applied by, for example, direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fountain coating, or other methods, and the thickness after drying is preferably 1 to 8 μm to achieve sufficient adhesiveness. It is more preferably 2 to 7 μm, and even more preferably 3 to 6 μm. If the coating thickness is less than 1 μm, it becomes difficult to bond the entire surface, and adhesive strength decreases. On the other hand, if it exceeds 8 μm, it takes a long time for the film to completely cure, unreacted material is likely to remain, and adhesive strength decreases.

[0080] [Print layer] Furthermore, in the present invention, at least one printed layer may be laminated between the laminate film and the film to be laminated or on the outside thereof.

[0081] As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks are preferably used. Examples of resins used in printing inks include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printing layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. To dry the solvent after printing, known drying methods such as hot air drying, heat roll drying, and infrared drying can be used.

[0082] [Heat-sealable resin layer] When the laminated film of the present invention is used as a packaging material, it is preferable to form a laminate having a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the inorganic thin film layer and protective layer side, but it may also be provided on the outside of the base film layer (the side opposite the inorganic thin film layer). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. The thermoplastic polymer that forms the heat-sealable resin layer may be any polymer that can exhibit sufficient sealant adhesiveness, and examples of such polymers include polyethylene resins such as HDPE, LDPE, and LLDPE, polypropylene resins, ethylene-vinyl acetate copolymers, ethylene-α-olefin random copolymers, and ionomer resins.

[0083] [Properties of laminated film] The present invention is characterized in that, when the oxygen permeability of a laminate structure obtained by bonding a laminate film to a heat-sealable resin layer under measurement conditions of 23°C x 65% RH is defined as A, and the oxygen permeability of the structure under measurement conditions of 23°C x 65% RH after treating the structure with 95°C hot water for 30 minutes is defined as B, the rate of change X in oxygen permeability before and after hot water treatment satisfies the following: X(%)=(B / A)×100≦200 This ensures practically acceptable barrier performance even after hot water treatment. The change rate X is preferably 180% or less, more preferably 160% or less. If the change rate exceeds 200%, the barrier deterioration rate after hot water treatment will be so great that sufficient preservation of the contents may not be ensured.

[0084] In the present invention, the laminate structure obtained by laminating the laminated film with the heat-sealable resin layer has an oxygen permeability A of 20 ml / m under the conditions of 23°C x 65% RH. 2 d MPa or less is preferable in terms of exhibiting good gas barrier properties. 2 ·d·MPa or less, more preferably 16 ml / m 2 ·d·MPa or less. Oxygen permeability is 20ml / m 2 If the pressure exceeds 1.5 MPa, it becomes difficult to use the material in applications that require high gas barrier properties, such as sterilization.

[0085] The laminated film of the present invention has a water vapor permeability of 3.0 g / m under the conditions of 40°C x 90% RH when laminated with a heat-sealable resin layer. 2 It is preferable that the surface roughness is 2.8 g / m²·d or less, and more preferably 2.6 g / m²·d or less, in order to achieve good gas barrier properties. 2 d or less. The water vapor permeability is 3.0 g / m 2 If the value exceeds d, it becomes difficult to use the film in applications that require high gas barrier properties, such as sterilization applications.

[0086] The present invention is characterized in that the number of pinholes after a laminate structure obtained by bonding a laminate film to a heat-sealable resin layer is subjected to a Gelboflex treatment at 1°C x 1000 times is 5 or less. This ensures that the bag will not tear or develop holes due to its toughness even when subjected to loads such as bending during bag-making processing, filling, sterilization processing, and transportation, and therefore maintains sufficient strength as a package. The number of pinholes is preferably 4 or less, more preferably 3 or less. If the number of pinholes exceeds 5, there is a risk that the bag will tear or develop holes during the processing described above.

[0087] In packaging materials made using the laminated film of the present invention, the total thickness of the films and adhesive is preferably 20 to 140 μm. It is more preferably 25 to 135 μm, and even more preferably 30 to 130 μm. By keeping the total thickness of the packaging material within this range, a package can be obtained that exhibits the necessary physical properties, such as the firmness required for the packaging material, as well as the necessary strength and barrier performance. If the total thickness is less than 20 μm, the bag will not have enough firmness and will not stand on its own. Furthermore, the bag will not have enough strength, and may be prone to tearing or holes. On the other hand, if the total thickness exceeds 140 μm, the bag will be too stiff, making it difficult to handle, and will increase the cost of the package, which is economically undesirable.

[0088] As described above, the packaging material made using the laminated film of the present invention has excellent barrier properties, stiffness, toughness, and resistance to thermal sterilization, and therefore can be used as various packages. Examples of packages include those for general food, frozen food, vacuum packaging, boiled retort food, and microwave heating.

[0089] The shape of the packaging material made using the laminated film of the present invention is not particularly limited and can take various shapes, such as three-sided or four-sided pouches, standing pouches, spout pouches, etc.

[0090] The contents to be filled in the packaging bag using the packaging material of the present invention are not particularly limited, and may be liquid, powder, or gel. The contents may also be food or non-food. [Example]

[0091] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. Various evaluations were carried out by the following measurement methods, and unless otherwise specified, measurements were carried out in a measurement room at 23°C and a relative humidity of 65%.

[0092] (1) Haze value of base film Measurement was carried out using a direct reading haze meter manufactured by Toyo Seiki Seisakusho Co., Ltd. in accordance with JIS-K-7105.

[0093] (2) Thickness of the base film The film was divided into 10 equal parts in the TD direction (for narrow films, the division was made to ensure a width that would allow thickness measurement), and 10 100mm films were cut out in the MD direction, and conditioned for at least 2 hours in an environment at a temperature of 23°C and a relative humidity of 65%. The thickness of the center of each sample was measured using a thickness measuring device made by Tester Sangyo, and the average value was taken as the thickness.

[0094] (3) Measurement of the biomass content of the base film The biomass content of the obtained film was determined by radiocarbon (C14) measurement according to ASTM D6866-16 Method B (AMS).

[0095] (4) Heat shrinkage rate of the base film The heat shrinkage was measured according to the following formula in accordance with the dimensional change test method described in JIS C2318, except that the test temperature was 160°C and the heating time was 10 minutes. Heat shrinkage rate = [(length before treatment - length after treatment) / length before treatment] x 100 (%) (5) Impact strength of the base film Measurements were made using a film impact tester manufactured by Toyo Seiki Seisakusho, Ltd. The measured values ​​were converted to values ​​per 15 μm thickness and expressed as J (joules) / 15 μm. (6) Puncture strength of base film Measurements were made in accordance with "2. Testing Methods for Strength, etc." in "Specifications and Criteria for Foods, Food Additives, etc., Part 3: Apparatus and Containers / Packaging" (Ministry of Health and Welfare Notification No. 20, 1982) under the Food Sanitation Act. A needle with a tip diameter of 0.7 mm was pierced into the film at a piercing speed of 50 mm / min, and the strength with which the needle penetrated the film was measured, and this was taken as the piercing strength. Measurements were made at room temperature (23°C), and the piercing strength (unit: N) of the obtained film was divided by the actual thickness of the film to obtain the piercing strength (unit: N / μm).

[0096] (7) Composition and thickness of inorganic thin film layer (C) on substrate film 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, "supermini200") based on a previously prepared calibration curve. The excitation X-ray tube conditions were 50 kV and 4.0 mA.

[0097] (8) Amount of protective layer (D) attached In each example and comparative example, each laminated film obtained at the stage of laminating a specified protective layer (D) was used as a sample, and a 100 mm x 100 mm test piece was cut out from this sample, and the coating layer was wiped off with either water, ethanol or acetone, and the amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0098] (9) Evaluation method for surface hardness of protective layer (D) The surface hardness of each laminate film obtained in the examples and comparative examples was measured using a dynamic ultra-microhardness tester ("DUH-211" manufactured by Shimadzu Corporation). Specifically, a hardness measurement test was performed on the protective layer surface of a single laminate film fixed to a glass plate with an adhesive using a diamond triangular pyramid indenter (Berkovich type) with an edge angle of 115° in a load-unload test, and the resulting Martens hardness was taken as the surface hardness value. The test conditions were a test force of 0.1 mN, a loading rate of 0.02 mN / s, and a holding time of 2 seconds.

[0099] (10) Method for Evaluating Water Contact Angle on the Surface of Protective Layer (D) For each laminate film obtained in the Examples and Comparative Examples, the contact angle was measured on the protective layer surface of the laminate film using a contact angle measuring device ("KRUSS DSA100" manufactured by Sanyo Trading Co., Ltd.) in an atmosphere of room temperature 23°C and relative humidity 65% ​​using the sessile drop method. 2 μl of water was dropped on the coating layer surface, and the contact angle value was measured 1 second after the drop.

[0100] (11) Preparation of laminate for evaluation Adhesive 1, which will be described later, was applied to the protective layer surface of each laminate film obtained in the Examples and Comparative Examples so that the thickness would be 3 μm after drying at 80°C. A linear low-density polyethylene film (L4102 manufactured by Toyobo; thickness 40 μm; referred to as LL1) was then dry-laminated as a heat-sealable resin layer on a metal roll heated to 60°C, and aging was carried out at 40°C for 4 days to obtain a laminate gas barrier laminate for evaluation (hereinafter sometimes referred to as a "laminate laminate"). Adhesive 1: Base C: Polyester / Curing agent C: Isocyanate curing adhesive (TM569 / cat10L manufactured by Toyo Morton Co., Ltd.)

[0101] (12) Evaluation method for oxygen permeability of laminated materials The oxygen permeability A of the laminate produced in (11) above was measured in accordance with JIS-K7126 Method B using an oxygen permeability measuring device (OX-TRAN (registered trademark) 2 / 22 manufactured by MOCON) under an atmosphere of 23°C and 65% RH. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side of the laminate to the heat-sealable resin layer side.

[0102] (13) Evaluation method for oxygen permeability of laminated body after sterilization treatment The laminate prepared in (11) above was subjected to a wet heat treatment by being kept in hot water at 95°C for 30 minutes, and then dried at 40°C for 1 day (24 hours). The oxygen permeability B of the resulting treated laminate was measured in the same manner as above.

[0103] (14) Evaluation method for water vapor permeability of laminated materials The water vapor permeability of the laminate produced in (11) above was measured in accordance with JIS-K7129 Method B using a water vapor permeability measuring device ("PERMATRAN-W 3 / 33MG" manufactured by MOCON) under an atmosphere of 40°C temperature and 90% RH. The water vapor permeability was measured in the direction in which water vapor permeated from the heat-sealable resin layer side to the laminate film side.

[0104] (15) Pinhole resistance of laminated laminates The number of pinholes due to flexural fatigue was measured for the laminated laminate prepared in (11) above using a Gelbo Flex Tester manufactured by Rigaku Kogyosha Co., Ltd., using the following method. The sample was cut into a 12-inch x 8-inch cylindrical shape with a diameter of 3.5 inches. One end of the cylindrical film was fixed to the fixed head of the Gelbo Flex Tester, and the other end to the movable head. The initial gripping distance was 7 inches. The test film was subjected to a 440° twist in the first 3.5 inches of the stroke, followed by a linear horizontal movement for the next 2.5 inches to complete the entire stroke. This bending fatigue test was repeated 1,000 times at a speed of 40 times per minute, and the number of pinholes that appeared in the laminated film was counted. The measurement was performed at 1°C. The test film was placed on filter paper (Advantec, No. 50) with the L-LDPE film side facing down, and the four corners were secured with cellophane tape (registered trademark). Ink (Pilot ink (product number INK-350-Blue) diluted 5 times with pure water) was applied to the test film and spread over the entire surface using a rubber roller. After wiping off any excess ink, the test film was removed and the number of ink dots on the filter paper was counted.

[0105] The laminated films used in Examples 1 to 7 and Comparative Examples 1 to 4 are listed below.

[0106] (Manufacturing of base film ONY1) Using an apparatus consisting of two extruders and a 380 mm wide co-extrusion T-die, the layers were laminated using the feed block method in a configuration of functional layer (B layer) / base layer (A layer) / functional layer (B layer), and the molten resin of the resin composition below was extruded from the T-die into a film, which was then cast onto a cooling roll controlled to 20°C and electrostatically adhered to obtain an unstretched film with a thickness of 200 μm. The resin compositions of the base layer (layer A) and the functional layer (layer B) are as follows. Resin composition constituting the base layer (Layer A): a polyamide resin composition consisting of 89.5 parts by mass of polyamide 6 (manufactured by Toyobo Co., Ltd., relative viscosity 2.8, melting point 220°C) and 10.5 parts by mass of polybutylene terephthalate adipate PBAT (manufactured by BASF under the trade name "Ecoflex"), glass transition temperature -31.3°C, melting point 120°C). Resin composition constituting the functional layer (Layer B): A resin composition consisting of 95 parts by mass of polyamide 6 (manufactured by Toyobo Co., Ltd., relative viscosity 2.8, melting point 220°C), 5.0 parts by mass of polyamide MXD6 (manufactured by Mitsubishi Gas Chemical Co., Ltd., relative viscosity 2.1, melting point 237°C), 0.54 parts by mass of porous silica microparticles A (manufactured by Fuji Silysia Chemical Ltd., average particle diameter 2.0 μm, pore volume 1.6 ml / g), and 0.15 parts by mass of fatty acid bisamide (ethene bisstearamide, manufactured by Kyoeisha Chemical Co., Ltd.). The feed block configuration and extrusion rate of the extruder were adjusted so that the total thickness of the biaxially oriented polyamide film was 15 μm, the thickness of the base layer (layer A) was 9 μm, and the thickness of the functional layer (layer B) was 3 μm on each side. The resulting unstretched film was fed into a roll-type stretching machine and stretched 1.73 times in the MD direction at 80°C using the differential speed of the rolls, followed by a further stretch of 1.85 times at 70°C. This uniaxially stretched film was then continuously fed into a tenter-type stretching machine, preheated at 110°C, and stretched 1.2 times in the TD direction at 120°C, 1.7 times at 130°C, and 2.0 times at 160°C. It was then heat-set at 218°C and relaxed 7% at 218°C. The surface to be dry-laminated with a linear low-density polyethylene film was then corona-discharge-treated to yield biaxially oriented polyamide film ONY1. The evaluation results of the resulting film are shown in Table 1.

[0107] (Manufacturing of base film ONY2) Using an apparatus consisting of two extruders and a 380 mm wide co-extrusion T-die, layers were laminated in a B layer / A layer / B layer configuration using the feed block method, and a molten resin of the resin composition shown below was extruded from the T-die into a film, which was then cast onto a cooling roll controlled to 20°C and electrostatically adhered to obtain an unstretched film with a thickness of 130 μm. The resin compositions of the A and B layers are as follows. Resin composition constituting layer A: a polyamide resin composition consisting of 89.5 parts by mass of polyamide 6 (manufactured by Toyobo Co., Ltd., relative viscosity 2.8, melting point 220°C) and 10.5 parts by mass of polybutylene terephthalate adipate (manufactured by BASF under the trade name "Ecoflex"), glass transition temperature -31.3°C, melting point 120°C). Resin composition constituting layer B: a resin composition consisting of 95 parts by mass of polyamide 6 (manufactured by Toyobo Co., Ltd., relative viscosity 2.8, melting point 220°C), 5.0 parts by mass of polyamide MXD6 (manufactured by Mitsubishi Gas Chemical Co., Ltd., relative viscosity 2.1, melting point 237°C), 0.54 parts by mass of silica particles B (porous silica microparticles, manufactured by Fuji Silysia Chemical Ltd., average particle diameter 3.9 μm, oil absorption 320 ml / 100 g), 0.075 parts by mass of silica particles C (porous silica microparticles, manufactured by Fuji Silysia Chemical Ltd., average particle diameter 2.7 μm, oil absorption 170 ml / 100 g), and 0.15 parts by mass of fatty acid bisamide (ethene bisstearamide, manufactured by Kyoeisha Chemical Co., Ltd.). The feed block configuration and extrusion rate of the extruder were adjusted so that the total thickness of the biaxially oriented polyamide film was 10 μm, the thickness of the base layer (layer A) was 6 μm, and the thickness of the functional layer (layer B) was 2 μm on each side. The resulting unstretched film was fed into a roll-type stretching machine and stretched 1.73 times in the MD direction at 80°C using the differential speed of the rolls, followed by a further stretch of 1.85 times at 70°C. This uniaxially stretched film was then continuously fed into a tenter-type stretching machine, preheated at 110°C, and stretched 1.2 times in the TD direction at 120°C, 1.7 times at 130°C, and 2.0 times at 160°C. It was then heat-set at 218°C and relaxed 7% at 218°C. The surface to be dry-laminated with a linear low-density polyethylene film was then corona-discharged to yield biaxially stretched polyamide film ONY2. The evaluation results of the resulting biaxially stretched film are shown in Table 1.

[0108] (Manufacturing of base film ONY3) A biaxially stretched film ONY3 was obtained in the same manner as ONY1, except that the resin composition of the base layer (A layer) was Polyamide 11 (manufactured by Shusei Co., Ltd., relative viscosity 2.5, melting point 186°C), a polyamide resin at least partly derived from biomass. The evaluation results of the obtained biaxially stretched film are shown in Table 1.

[0109] (Manufacturing of base film ONY4) A biaxially stretched film ONY4 was obtained in the same manner as ONY1, except that polybutylene terephthalate adipate PBAT was not included in the resin composition of the base layer (layer A). The evaluation results of the obtained biaxially stretched film are shown in Table 1.

[0110] (Manufacturing of base film ONY5) After obtaining a uniaxially stretched film using the same materials and method as for the base film ONY4, a coating solution composed of the following mass ratio was applied to one side of the film as a coating layer using the fountain coat method. This was then introduced into a tenter stretching machine and treated in the same manner as for ONY1 to obtain a biaxially stretched film ONY4 with a coating layer of 0.075 g / m2. The evaluation results of the obtained biaxially stretched film are shown in Table 1. Coating liquid used to create the coating layer on the film Water 33% by mass Isopropanol 7% by mass Water-dispersible polyester resin "AGN201" (solid content 25%, Takemoto Oil & Fat) 60% by mass

[0111] (Inorganic thin film layer (C)) The method for producing the inorganic thin film layer (C) used in each of the Examples and Comparative Examples will be described below. The inorganic thin film layer (C) used in Examples 1 to 7 and Comparative Examples 1 to 6 is shown in Table 2.

[0112] (Formation of inorganic thin film layer 1 (vapor deposition 1)) As the inorganic thin film layer 1, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the corona-treated surface of the base film by electron beam evaporation. The evaporation sources used were 3-5 mm particulate SiO2 (purity 99.9%) and Al2O3 (purity 99.9%). The thickness of the inorganic thin film layer (SiO2 / Al2O3 composite oxide layer) in the film thus obtained (film containing an inorganic thin film layer / coating layer) was 20 nm. The composition of this composite oxide layer was SiO2 / Al2O3 (mass ratio) = 70 / 30.

[0113] (Formation of inorganic thin film layer 2 (deposition 2)) Silicon oxide was vapor-deposited onto the corona-treated surface of the base film to form the inorganic thin film layer 2. Using a small vacuum deposition device (ULVAC KIKO Co., Ltd., VWR-400 / ERH), the pressure was reduced to 10 Pa or less, and silicon oxide was then placed in a Nilaco vapor deposition source B-110 from below the substrate and heated to evaporate, forming a 40 nm-thick silicon oxide film on the film.

[0114] (Protective layer (D)) The materials and preparation methods of the protective layer (D) used in each example and comparative example are described below. The materials used in examples 1 to 7 and comparative examples 2 to 4 are shown in Table 2.

[0115] [Polyester resin (a)] As the polyester component, polyester polyol (DIC Corporation's "DF-COAT GEC-004C": solid content 30%) was used.

[0116] [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.

[0117] [Silane coupling agent (c)] As the silane coupling agent, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane ("KBM-603" manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

[0118] [Urethane resin (d)] In a four-neck flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, 143.95 parts by mass of meta-xylylene diisocyanate, 25.09 parts by mass of 4,4'-methylenebis(cyclohexyl isocyanate), 28.61 parts by mass of ethylene glycol, 5.50 parts by mass of trimethylolpropane, 12.37 parts by mass of dimethylolpropionic acid, and 120.97 parts by mass of methyl ethyl ketone as a solvent were mixed and stirred at 70 ° C. under a nitrogen atmosphere. It was confirmed that the reaction solution reached the predetermined amine equivalent. Next, the reaction solution was cooled to 35 ° C., and then 9.14 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 794.97 parts by weight of water was added to a reaction vessel equipped with a high-speed homodisperser, and the temperature was adjusted to 15°C. While stirring and mixing at 2000 min-1, the polyurethane prepolymer solution was added and dispersed in water. An amine aqueous solution containing 22.96 parts by weight of 2-[(2-aminoethyl)amino]ethanol and 91.84 parts by weight of water was then added. Next, an amine aqueous solution containing 2.38 parts by weight of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (trade name: KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) and 9.50 parts by weight of water was added, and a chain extension reaction was carried out. Subsequently, methyl ethyl ketone and a portion of the water were removed under reduced pressure to obtain a polyurethane dispersion (E) with a solids content of 25% by weight and an average particle size of 70 nm. The resulting polyurethane dispersion (D-1) had a Si content (calculated based on the charge) of 1200 mg / 1 kg and a metaxylylene group content (calculated based on the charge) of 32% by weight.

[0119] [Coating solution 1 consisting of materials (a), (b), and (c)] Silane coupling agent (c), acetone, and polyisocyanate crosslinker (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 propylene glycol monomethyl ether (PGM), and polyester resin (a) was added to obtain a coating solution. The mixing ratio is shown below. Acetone 1.91% by mass Silane coupling agent (c) 0.34% by mass Isocyanate (b) 4.99% by mass Methyl ethyl ketone 63.70% by mass PGM 16.00% by mass Polyester resin (a) 13.06% by mass

[0120] [Coating solution 2 consisting of materials (a), (b), and (c)] Coating liquid 2 was obtained in the same manner as for coating liquid 1, except that the mixing ratio was changed as follows: Acetone 1.43% by mass Silane coupling agent (c) 0.25% by mass Isocyanate (b) 3.74% by mass Methyl ethyl ketone 68.78% by mass PGM 16.00% by mass Polyester resin (a) 9.80% by mass

[0121] [Coating solution 3 consisting of materials (a), (b), and (c)] Coating Solution 3 was obtained in the same manner as Coating Solution 1, except that the mixing ratio was changed as follows: Acetone 2.86% by mass Silane coupling agent (c) 0.51% by mass Isocyanate (b) 7.49% by mass Methyl ethyl ketone 53.55% by mass PGM 16.00% by mass Polyester resin (a) 19.59% by mass

[0122] [Coating solution 4 consisting of materials (a), (b), and (c)] Coating Solution 4 was obtained in the same manner as Coating Solution 1, except that the mixing ratio was changed as follows: Acetone 1.81% by mass Silane coupling agent (c) 0.32% by mass Isocyanate (b) 7.47% by mass Methyl ethyl ketone 67.47% by mass PGM 16.00% by mass Polyester resin (a) 6.93% by mass

[0123] [Coating liquid 5 consisting of material (d)] The following coating agents were mixed to prepare coating liquid 5. Water 35.83% by mass Isopropanol 47.50% by mass Silane coupling agent (c) 0.040% by mass Urethane resin (d) 16.63% by mass

[0124] [Coating liquid 6 consisting of acrylic resin] Polymethacrylic acid with an average molecular weight of 30,000 was prepared. A polyurethane resin was prepared by reacting a 1:9 mixture of polypropylene glycol (average molecular weight 2,000) and a polyester polyol (average molecular weight 2,000) obtained by polymerization of neopentyl glycol and adipic acid with isophorone diisocyanate at an NCO / OH equivalent ratio of 3:2 to obtain a prepolymer with terminal isocyanates. This prepolymer was then extended with 1.1 equivalents of isophorone diamine to obtain a polyurethane-urea resin with amino groups at the terminals. The polymethacrylic acid was dissolved in isopropyl alcohol, and the polyurethane-urea resin was dissolved in a 2:2:1 mixture of ethyl acetate / methyl ethyl ketone / isopropyl alcohol (each with a solids concentration of 30% by mass). These solutions were mixed at a 1:1 ratio to prepare a solution with a solids concentration of 15% by mass in a 1:1 mixture of ethyl acetate / isopropyl alcohol. To this solution, an epoxy curing agent (Epotohto YP300, 100% non-volatile content: manufactured by Tohto Chemical Co., Ltd.) and a silane coupling agent (Shin-Etsu Silicon KBM403, 100% non-volatile content: manufactured by Shin-Etsu Chemical Co., Ltd.) were added in an amount of 10% each relative to the solid content of the coating liquid to form Coating Liquid 6.

[0125] [Coating liquid 7 consisting of polyvinyl alcohol] A solution of tetraethoxysilane hydrolyzed with 0.02 mol / L hydrochloric acid was added to a 5 wt % aqueous solution of polyvinyl alcohol resin (PVA) with a saponification degree of 99% and a polymerization degree of 2400 in a weight ratio of SiO2 / PVA = 60 / 40 to prepare coating solution 7.

[0126] (Coating each coating liquid onto the film (laminating protective layer (D))) Any of the above-mentioned coating solutions 1 to 7 was applied to the inorganic thin film layer of the base film by gravure roll coating, pre-dried for 5 seconds in a dry oven at 110°C, and then dried for 10 seconds in a dry oven at 150°C to obtain a protective layer. The protective layer had an adhesion weight of 0.25 g / m2. The film was then subjected to a heat treatment at 40°C for 96 hours. In this manner, a laminated film provided with a protective layer (D) was produced.

[0127] In this manner, a laminated film having an inorganic thin film layer and a protective layer on a substrate film was prepared.

[0128] In each example and comparative example, each laminate film was used, and multiple films were bonded together by dry lamination using the adhesive described above to form a laminate having the configuration shown in Table 2. Various evaluations were also carried out on the resulting laminate. The results are shown in Table 2.

[0129] [Table 1]

[0130] [Table 2] [Industrial Applicability]

[0131] The present invention provides a laminated film for packaging that can maintain gas barrier properties and high toughness of the base film even after hot water treatment, and is environmentally friendly and highly convenient. Moreover, the packaging material of the present invention can be easily produced with fewer processing steps, so it is excellent in both economy and production stability, and can provide packages with uniform properties.

Claims

1. A laminated film comprising a polyamide substrate film, an inorganic thin film layer, and a protective layer laminated in that order, the laminated film satisfying the following requirements (a) to (d): (a) When the oxygen permeability of a laminated structure obtained by bonding the laminated film to a heat-sealable resin layer under measurement conditions of 23°C x 65% RH is defined as A, and the oxygen permeability of the structure after treating it with hot water at 95°C for 30 minutes under measurement conditions of 23°C x 65% RH is defined as B, the rate of change X in oxygen permeability before and after hot water treatment satisfies the following: X (%) = (B / A) x 100 ≦ 200 (b) The polyamide substrate film and the inorganic thin film layer are adjacent to each other. (c) The laminated structure obtained by laminating the laminated film with a heat-sealable resin has 5 or less pinholes after being subjected to a Gelboflex treatment at 1°C x 1,000 times. (d) The surface hardness of the protective layer surface of the laminated film is 200 to 350 N / mm ２ And the water contact angle is 60 degrees or more.

2. 2. The laminated film according to claim 1, wherein the inorganic thin film layer is an inorganic thin film layer made of any one of aluminum, aluminum oxide, silicon oxide, and a composite oxide of silicon oxide and aluminum oxide.

3. 2. The laminated film according to claim 1, wherein the protective layer is a protective layer containing a polyester resin having a urethane skeleton.

4. 2. The laminated film according to claim 1, which is used for heating in a microwave oven.

5. A packaging material characterized by using the film according to any one of claims 1 to 4 laminated thereto.

6. A packaging bag made using the packaging material according to claim 5.

7. A package in which an item is packaged using the packaging material according to claim 5.

8. A packaged product in which an item is packaged using the packaging bag according to claim 6.

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