Gas barrier film

Abstract

To provide a gas barrier film which exhibits excellent gas barrier property and has sufficient adhesion strength as a packaging material.SOLUTION: A gas barrier film has a resin base material, an oxygen barrier film on at least one surface of the resin base material, and a substrate layer and / or an inorganic oxide layer between the resin base material and the oxygen barrier film, and has a black area ratio of the one surface measured by the following measurement method of 0.15% or less. [Measurement method] The method photographs an arbitrary region of 1,281 μm square of the one surface of the resin base material by an optical microscope, acquires a photographic image of 1,024×1024 pixel, converts the photographed image into a monochrome image with 256 gradations using an image analysis software, sets a value obtained by subtracting 30 from a mode of brightness in the monochrome image to be a threshold, binarizes the brightness when a value less than the threshold is defined to be black and a value equal to or more than the threshold is defined to be white, and sets a ratio of the total area of a black region having a size of 100 μm2 or more in the region of 1,281 μm square to be a black area ratio.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This disclosure relates to a gas barrier film and a method for manufacturing the same. [Background technology]

[0002] Packaging materials used for food, pharmaceuticals, and other products require gas barrier properties to prevent the intrusion of gases (water vapor, oxygen, etc.) that alter the contents, thereby suppressing deterioration and spoilage and maintaining their function and quality. For this reason, film materials with gas barrier properties (gas barrier films) are used for these packaging materials.

[0003] As gas barrier films, those in which a gas barrier layer made of a material having gas barrier properties is provided on the surface of a resin substrate are known. Known gas barrier layers include metal foils, metal vapor-deposited films, and films formed by the wet-coat method. As films that exhibit oxygen barrier properties, known films include resin films formed from coating agents containing water-soluble polymers and resins such as polyvinylidene chloride, and inorganic layered mineral composite resin films formed from coating agents containing water-soluble polymers and inorganic layered minerals (Patent Document 1). Furthermore, as gas barrier layers, gas barrier layers have been proposed in which a vapor-deposited thin film layer made of inorganic oxides and a gas barrier composite film containing an aqueous polymer, an inorganic layered compound, and a metal alkoxide are sequentially laminated (Patent Document 2), and gas barrier layers containing polyvalent metal salts of carboxylic acids, which are reaction products of carboxyl groups of polycarboxylic acid polymers and polyvalent metal compounds (Patent Document 3).

[0004] To improve gas barrier properties, for example, Patent Document 4 proposes a gas barrier film in which a coating is formed on at least one surface of the substrate, and the surface roughness parameter Rt / Ra of the coating surface is 20 or less. Here, Rt is the distance between the highest peak and the deepest trough of the surface roughness curve, and Ra is the centerline average roughness. According to the gas barrier film of Patent Document 4, gas barrier properties are improved. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6191221 [Patent Document 2] Japanese Patent Publication No. 2000-254994 [Patent Document 3] Patent No. 4373797 [Patent Document 4] Japanese Patent Application Publication No. 9-150484 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, gas barrier films with coatings applied to the surface of resin substrates using wet coating, vapor deposition, or sputtering methods sometimes exhibited inconsistent oxygen barrier properties depending on the manufacturing lot. Specifically, the oxygen barrier properties of the gas barrier film were sometimes inferior to the intended oxygen barrier properties, that is, the oxygen barrier properties expected from the materials constituting the coating and the thickness of the coating. This problem tended to occur more easily when the thickness of the coating was thin. As a result, the thickness of the gas barrier layer had to be increased unnecessarily to compensate, leading to problems such as poor productivity and excessive material costs.

[0007] Furthermore, while polyolefin resin films are inexpensive and have high water vapor barrier properties, making them commonly used as packaging materials, they have the drawback of poor adhesion to gas barrier coatings. This results in inferior laminate strength when laminated with heat-sealable resin films to create gas barrier packaging materials.

[0008] The present invention aims to provide a gas barrier film that exhibits excellent gas barrier properties by fully demonstrating its inherent oxygen barrier properties even with a thin coating thickness, and that also has sufficient adhesion strength to be used as a packaging material. [Means for solving the problem]

[0009] The gas barrier film according to the present invention comprises a resin substrate and an oxygen barrier coating formed on one side of the resin substrate, which is the first surface. Between the resin substrate and the oxygen barrier coating, there is at least one of a base layer and an inorganic oxide layer. The resin substrate has two or more resin layers, of which the resin layer forming the first surface is made of a polyolefin copolymer resin, and the first surface has 20 protrusions / mm² with a Ferret diameter of 8 μm or more, as measured by the measurement method described below. 2 The following is a gas barrier film. <Measurement method> A white LED line light source is used to illuminate an arbitrary 36.6 mm square area on the first surface of a resin substrate at a light source distance of 100 mm and an incident angle of 83°. The transmitted light at a measurement angle of 90° is captured by a monochrome line camera to obtain an image. A 3551 x 5684 pixel (2.5 x 4.0 mm) analysis image is extracted from the captured image, and protrusions with a diameter of 8 μm or more in the analysis image are counted. [Effects of the Invention]

[0010] According to the present invention, even with a thin coating thickness for imparting oxygen barrier properties, it is possible to provide a gas barrier film that fully exhibits its inherent oxygen barrier properties, shows excellent gas barrier properties, and has sufficient adhesion strength as a packaging material. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a cross-sectional view of the gas barrier film of Embodiment 1. [Figure 2] Figure 2 is an image taken with an optical microscope of one side of the resin substrate of Embodiment 1. [Figure 3] Figure 3 shows an example of a histogram used to calculate the black area ratio. [Figure 4] Figure 4 is a cross-sectional view of the gas barrier film of Embodiment 2. [Figure 5] Figure 5 is a schematic diagram illustrating a measuring device for measuring the number of protrusions on the first surface of a resin substrate. [Figure 6]Figure 6 is a schematic diagram illustrating the principle of detecting protruding parts. [Figure 7] Figure 7 shows a photograph of the first surface of the resin substrate in the example, and an analysis image showing the protrusions detected from the same image. [Figure 8] Figure 8 is a cross-sectional electron microscope image taken with a focused ion / electron beam processing observation system, showing that coating defects have occurred in the areas of the resin substrate where the AB agent is present. [Modes for carrying out the invention]

[0012] (Embodiment 1) To investigate the cause of the aforementioned problem, the inventors observed the surface and cross-section of a gas barrier film with poor oxygen barrier properties in detail using an optical microscope and an electron microscope. Cross-sectional electron microscopy observation using a focused ion / electron beam processing observation device revealed that defects several micrometers wide were present in the film at locations where the antiblocking agent (hereinafter also referred to as "AB agent") added to prevent blocking of the resin substrate was present. It is believed that these defects served as pathways for gas permeation, resulting in insufficient oxygen barrier performance.

[0013] The surface of the resin substrate has protrusions of various sizes due to the AB agent. There are variations in the protrusion height and density of the AB agent depending on the manufacturing lot of the resin substrate. When a gas barrier film is coated onto the surface of the resin substrate, the film does not form locally at the locations of the large protrusions, resulting in defects and unstable oxygen barrier properties.

[0014] Furthermore, by closely observing the transfer defects (sometimes called dot defects) of fine dots occurring in the highlight printing area of ​​the gas barrier film under a microscope, it was confirmed that dot defects are more likely to occur in areas where the aforementioned AB agent protrudes significantly.

[0015] Therefore, the inventors devised a method to quickly and accurately grasp the wide surface condition of a resin substrate that affects the oxygen barrier properties and printability of a gas barrier film, and performed a binarization process on optical microscope images of the resin substrate surface to obtain a 100 μm result. 2 We have discovered that when the total area ratio of the black regions (hereinafter referred to as the black area ratio) is 0.15% or less, the oxygen barrier performance is excellent and the printability on the gas barrier film is good, which led to this disclosure.

[0016] The gas barrier film of this disclosure will be described with reference to embodiments.

[0017] Figure 1 is a schematic cross-sectional view of the gas barrier film 1 according to Embodiment 1. The dimensional ratios in Figure 1 differ from those of the actual dimensions for the sake of explanation.

[0018] The gas barrier film 1 comprises a resin substrate 10, a base layer 30, an inorganic oxide layer 40, and an oxygen barrier coating 20. Note that either the base layer 30 or the inorganic oxide layer 40 may be omitted.

[0019] The base layer 30 is laminated in contact with one surface 12 of the resin substrate 10, and the inorganic oxide layer 40 is laminated on the opposite side of the base layer 30 from the surface in contact with the resin substrate 10. The inorganic oxide layer 40 is laminated in contact with the base layer 30, and the oxygen barrier film 20 is located in contact with the opposite side of the inorganic oxide layer 40 from the surface in contact with the base layer 30. If the base layer 30 is not provided, the inorganic oxide layer 40 is laminated on one surface 12 of the resin substrate 10. Also, if the inorganic oxide layer 40 is not provided, the oxygen barrier film 20 is laminated on the base layer 30.

[0020] <Resin substrate> The resin substrate 10 contains a resin. Examples of resins constituting the resin substrate 10 include olefin resins such as polyethylene, polypropylene, polymers of olefins having 2 to 10 carbon atoms, and propylene-ethylene copolymers; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamide resins such as aliphatic polyamides such as nylon 6 and nylon 66, and aromatic polyamides such as polymetaxylylene adipamide; vinyl resins such as polystyrene, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and ethylene-vinyl alcohol copolymer; acrylic resins such as polymethyl methacrylate and polyacrylonitrile (meth)acrylic monomers alone or copolymers; cellophane; and engineering plastics such as polycarbonate and polyimide. These resins may be used individually or in combination of two or more.

[0021] Examples of the resin substrate 10 include a single-layer film composed of a single resin, and a single-layer or laminated film using multiple resins. Alternatively, a laminated substrate may be used, in which the above resins are laminated onto another substrate (metal, wood, paper, ceramics, etc.). The resin substrate 10 may be a single layer or two or more layers. Preferred resin substrates 10 include polyolefin resin films (especially polyethylene films, polypropylene films, etc.), polyester resin films (especially polyethylene terephthalate resin films), and polyamide resin films (especially nylon films).

[0022] The resin substrate 10 may be an unstretched film, or a uniaxially or biaxially oriented film. From the viewpoint of excellent water vapor barrier properties, polyethylene film and polypropylene film are preferred as the resin substrate 10, and biaxially oriented polypropylene film (OPP) is particularly preferred. OPP may be a film made from at least one polymer selected from homopolymers, random copolymers, and block copolymers. Homopolymer is polypropylene consisting only of propylene. Random copolymer is polypropylene in which propylene, the main monomer, and a small amount of comonomers different from propylene are randomly copolymerized to form a homogeneous phase. Block copolymer is polypropylene in which propylene, the main monomer, and the above comonomers copolymerize in a block-like manner or polymerize into a rubbery state to form a heterogeneous phase. When the resin substrate 10 is OPP, the OPP may be one layer or two or more layers.

[0023] One surface 12 of the resin substrate 10 may be subjected to surface treatments such as chemical treatment, solvent treatment, corona treatment, low-temperature plasma treatment, or ozone treatment in order to improve adhesion with the underlayer 30 or the inorganic oxide layer 40.

[0024] The resin substrate 10 may contain additives such as fillers, antiblocking agents, antistatic agents, plasticizers, lubricants, and antioxidants. These additives may be used individually or in combination of two or more.

[0025] When the resin substrate 10 contains an antiblocking agent (hereinafter also referred to as "AB agent"), irregularities originating from the AB agent are formed on one surface 12 of the resin substrate 10. By containing the AB agent, the resin substrate 10 can be given protrusions on its surface, thereby suppressing the occurrence of blocking in the film. In other words, by containing the AB agent, the resin substrate 10 can improve the blocking resistance of the film. As a result, the film can be made easier to wind up, and the processing characteristics of the film can be improved. Therefore, it is preferable for the resin substrate 10 to contain the AB agent. On the other hand, if a large protrusion is formed on one surface 12 of the resin substrate 10, defects that serve as pathways for gas permeation are more likely to occur in the underlayer 30, inorganic oxide layer 40, and oxygen barrier coating 20 formed thereon. As a result, the oxygen barrier properties of the gas barrier film 1 may decrease.

[0026] If the resin substrate 10 contains agent AB, the agent AB is dispersed within the resin substrate 10. Multiple protrusions originating from agent AB are locally present on one surface 12 or the other surface 14 of the resin substrate 10. On one surface 12 and the other surface 14, agent AB may be exposed or covered with resin.

[0027] The AB agent is a solid particle, and examples include organic particles and inorganic particles. Examples of organic particles include polymethyl methacrylate particles, polystyrene particles, and polyamide particles. These organic particles can be obtained, for example, by emulsion polymerization or suspension polymerization. Examples of inorganic particles include silica particles, zeolite, talc, kaolinite, and feldspar. These AB agents may be used individually or in combination of two or more.

[0028] Considering the appearance, transparency, potential for detachment of the AB agent, and antiblocking performance of the gas barrier film 1, the average particle size of the AB agent is preferably, for example, 0.1 to 5 μm. The average particle size of the AB agent is the weight-average diameter measured by the Coulter method.

[0029] If the resin substrate 10 contains an AB agent, the content of the AB agent is preferably 0.05 to 0.5 parts by mass per 100 parts by mass of the resin constituting the resin substrate 10. If the content of the AB agent is above the lower limit, it is easier to improve the processing characteristics of the film that is the raw material for the resin substrate 10. If the content of the AB agent is below the upper limit, it is easier to suppress the decrease in the oxygen barrier properties of the gas barrier film 1.

[0030] The black area ratio of one side 12 of the resin substrate 10 is 0.15% or less, more preferably 0.12% or less, and even more preferably 0.10% or less. When the black area ratio is below the above upper limit, the oxygen barrier properties of the gas barrier film 1 are more easily improved. In addition, when the black area ratio is below the above upper limit, the printability of the gas barrier film 1, especially when using polypropylene film or polyethylene terephthalate resin film, is more easily improved. The lower limit of the black area ratio is not particularly limited and is 0% or more.

[0031] Here, "improving printability" means suppressing ink loss (sometimes called dot loss) in highlight areas (printed areas with a low dot area ratio) when gravure printing is performed on the oxygen barrier coating 20 of the gas barrier film. The black area ratio can be adjusted, for example, by the material, average particle size and content of the AB agent contained in the resin substrate 10, and the properties of the resin forming one side 12 of the resin substrate 10, as well as the film manufacturing conditions.

[0032] When the surface brightness of the resin substrate 10 is binarized and the areas that appear black (black spots) are observed with an electron microscope, protrusions are found. The larger the size of the black spots, the taller the height of the protrusions tends to be, especially at 100 μm. 2 In areas where black dots (protrusions) of the above size were present, coating defects in the oxygen barrier film and ink bleeding during printing were more likely to occur. In other words, the smaller the black area ratio, the fewer protrusions there are on one surface 12 of the resin substrate 10 that adversely affect the oxygen barrier properties and printability, thereby improving the oxygen barrier properties of the gas barrier film 1 and improving printability.

[0033] The black area ratio in this specification can be measured by the following measurement method. <Measurement method> An arbitrary 1281 μm square area on one side 12 of the resin substrate 10 is photographed with an optical microscope to obtain a 1024 × 1024 pixel image. An example of the image is shown in Figure 2.

[0034] Figure 2 is an image taken with an optical microscope of one surface 12 of the resin substrate 10. In Figure 2, 100 represents a flat area, and 110 represents a protrusion. Examples of protrusions 110 include foreign matter, AB agent, and undissolved resin. As shown in Figure 2, the flat area 100 appears gray, and the protrusions 110 appear black. The brightness of the flat area 100 corresponds to the mode of brightness, which will be discussed later.

[0035] Next, using image analysis software, the acquired 1024 x 1024 pixel images are converted into 256-level monochrome images. The luminance distribution in the converted monochrome images is plotted to create a histogram. An example of a histogram is shown in Figure 3.

[0036] In Figure 3, the horizontal axis represents the luminance when converted to a 256-level monochrome image. The luminance in the monochrome image is an integer between 0 and 255. The vertical axis represents the frequency of luminance. In Figure 3, the minimum value of the distributed luminance is 26, and the maximum value is 255. The mode of luminance is the value of luminance that is most frequently distributed in the monochrome image. In Figure 3, P represents the mode of luminance. In Figure 3, P = 160.

[0037] Next, a threshold value is set by subtracting 30 from the mode of luminance, and the luminance in the monochrome image is binarized, with values ​​below the threshold being treated as black and values ​​above the threshold being treated as white. In the monochrome image in Figure 3, the threshold value that marks the boundary between white and black is the value obtained by subtracting 30 from the mode of luminance (P-30). In Figure 3, the threshold value is 130. That is, in Figure 3, values ​​with a luminance of less than 130 are treated as "black," and values ​​with a luminance of 130 or more are treated as "white," and the image is binarized.

[0038] From the viewpoint of improving the accuracy of the black area ratio value, it is preferable that the brightness histogram of the acquired image has a sharp shape. Here, "sharp shape" can be determined, for example, by the size of the histogram width (hereinafter also called "full width at half maximum") W at half the peak height H of the mode P of the histogram (H / 2). The full width at half maximum W is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. If the full width at half maximum W is less than or equal to the above upper limit, the histogram has a sharp shape, and the accuracy of the black area ratio value can be improved. The lower limit of the full width at half maximum W is not particularly limited, but in practice it is 2 or more.

[0039] From the aforementioned binarized 1281×1281μm (1024×1024 pixel) image, 100μm 2 The black area ratio is defined as the ratio of the total area of ​​the black regions of the above size. Furthermore, the black area ratio is the arithmetic mean of the values ​​obtained in any three regions.

[0040] For optical microscopes, the Olympus OLS-4000 is preferred. For image analysis software, Scion ImageJ from Scion is preferred. stomach.

[0041] I will now explain the image acquisition conditions. (Image acquisition conditions) To determine the black area ratio of the resin substrate 10, the side of the resin substrate 10 to which the coating agent is applied (one side 12) is facing upwards, and the resin substrate 10 is attached to a slide glass using black film double-sided tape (Teraoka Seisakusho, 7694). Using an optical microscope (Olympus, OLS-4000) with a 10x objective lens (MPFLN10), images of a 1281 μm × 1281 μm area are acquired from three arbitrary locations on the resin substrate 10 on the slide glass, as 1024 × 1024 pixel images. The amount of light used when capturing images is arbitrary, but it is preferable to adjust the amount of light so that the mode of the image brightness falls within the range of 80 to 200 in 256 gradations.

[0042] The image analysis conditions are as follows: (Image analysis conditions) • Color information discarded: 8-bit. • Binarization threshold: The value obtained by subtracting 30 from the mode of brightness. • Scale settings: Set Scale Distance in pixel: 1024, Known distance: 1281, Unit of length: μm ·Area measurement:Analyze Particles Size:100-Infinity(μm 2 Check Include Holes and Summarize. Under the image analysis conditions described above, the %Area value is calculated for each of the images captured from any three locations on the resin substrate 10, and the arithmetic mean of these %Area values ​​is taken as the black area ratio.

[0043] In this specification, the black area ratio is calculated by observing one surface 12 of the resin substrate 10 in a planar manner. Therefore, compared to conventional surface roughness measurements, the surface condition can be observed as a surface rather than as a line.

[0044] Conventional surface roughness values ​​vary depending on the measurement method and range. If the measurement area is small, the roughness may be underestimated because a small number of protrusions are not measured. Also, even when measuring roughness over a linear range of a certain length, such as with centerline average roughness, if large protrusions are measured, the roughness will be overestimated, but if not, the roughness will be underestimated.

[0045] As described herein, by defining the surface condition of the resin substrate by the black area ratio, the variation in the surface condition of the resin substrate can be reduced, and the surface condition of the resin substrate can be evaluated. Therefore, variations in oxygen barrier properties can be suppressed, and the oxygen barrier properties of the gas barrier film 1 can be more easily improved.

[0046] Controlling the black area ratio by binarization of optical microscope images is suitable for controlling oxygen barrier properties and printability because it allows for the detection of protrusions using a wide measurement range and a simple method.

[0047] The thickness of the resin substrate 10 is not particularly limited and is appropriately selected depending on the price and application, taking into consideration its suitability as a packaging material and its suitability for lamination of other coatings. In practical terms, the thickness of the resin substrate 10 is preferably 3 μm to 200 μm, more preferably 5 μm to 120 μm, even more preferably 6 μm to 100 μm, and particularly preferably 10 μm to 30 μm.

[0048] <Underlayer> The underlayer 30 is provided between the resin substrate 10 and the inorganic oxide layer 40 or the oxygen barrier film 20.

[0049] The underlayer 30 is a layer mainly composed of organic polymers and is sometimes called a primer layer. By providing the underlayer 30, the film-forming properties and adhesion strength of the inorganic oxide layer 40 or the oxygen barrier coating 20 can be improved.

[0050] The content of organic polymers in the base layer 30 may be, for example, 70% by mass or more, or 80% by mass or more. Examples of organic polymers include polyacrylic resin, polyester resin, polycarbonate resin, polyurethane resin, polyamide resin, polyolefin resin, polyimide resin, melamine resin, and phenolic resin. Considering the adhesion strength between the resin substrate 10 and the inorganic oxide layer 40 or oxygen barrier film 20, and the resistance to hot water, it is preferable to include at least one of polyacrylic resin, polyol resin, polyurethane resin, polyamide resin, or reaction products of these organic polymers. The base layer 30 may also contain a silane coupling agent, organic titanate, or modified silicone oil.

[0051] More preferably, the organic polymers include organic polymers having urethane bonds produced by the reaction of polyols having two or more hydroxyl groups at the polymer ends with an isocyanate compound, and / or organic polymers containing reaction products of polyols having two or more hydroxyl groups at the polymer ends with an organic silane compound such as a silane coupling agent or its hydrolysate.

[0052] Examples of polyols include at least one selected from acrylic polyols, polyvinyl acetals, polysyl polyols, and polyurethane polyols. Acrylic polyols may be obtained by polymerizing acrylic acid derivative monomers, or by copolymerizing acrylic acid derivative monomers with other monomers. Examples of acrylic acid derivative monomers include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of monomers copolymerized with acrylic acid derivative monomers include styrene.

[0053] The isocyanate compound enhances the adhesion between the resin substrate 10 and the inorganic oxide layer 40 or oxygen barrier film 20 through urethane bonding formed by reaction with the polyol. In other words, the isocyanate compound functions as a crosslinking agent or curing agent. Examples of isocyanate compounds include monomers such as aromatic tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic xylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), and isophorone diisocyanate (IPDI), polymers thereof, and derivatives thereof. The above-mentioned isocyanate compounds may be used individually or in combination of two or more.

[0054] Examples of silane coupling agents include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidooxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. Organosilane compounds are also included. These may also be hydrolyzed products of silane coupling agents. The organosilane compound may contain one of the above-mentioned silane coupling agents and their hydrolyzed products alone, or in combination of two or more.

[0055] The base layer 30 can be formed on one surface 12 of the resin substrate 10 using a mixture prepared by blending the above-mentioned components in any proportion in an organic solvent. The mixture may contain, for example, curing accelerators such as tertiary amines, imidazole derivatives, metal salt compounds of carboxylic acids, quaternary ammonium salts, and quaternary phosphonium salts; antioxidants such as phenolic, sulfuric, and phosphite-based agents; leveling agents; flow regulators; catalysts; crosslinking reaction accelerators; fillers, etc.

[0056] The mixture can be coated onto the resin substrate 10 using a well-known printing method such as offset printing, gravure printing, or screen printing, or a well-known coating method such as roll coating, knife edge coating, or gravure coating. After coating, the substrate layer 30 can be formed by heating to, for example, 50-200°C and drying and / or curing.

[0057] The thickness of the underlayer 30 is not particularly limited and may be, for example, 0.005 to 5 μm. The thickness may be adjusted according to the application or required properties. The thickness of the base layer 30 is preferably 0.01 to 1 μm, and more preferably 0.01 to 0.5 μm. If the thickness of the base layer 30 is 0.01 μm or more, sufficient adhesion strength between the resin substrate 10 and the inorganic oxide layer 40 or oxygen barrier film 20 can be obtained, and the oxygen barrier properties will also be good. If the thickness of the base layer 30 is 1 μm or less, it is easy to form a uniform coated surface, and drying load and manufacturing costs can be suppressed.

[0058] <Inorganic oxide layer> Examples of the inorganic oxide layer 40 include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, tin oxide, zinc oxide, and indium oxide. Aluminum oxide or silicon oxide are particularly preferred because they offer excellent productivity and superior heat resistance, heat resistance, and oxygen and water vapor barrier properties. The inorganic oxide layer 40 may contain one of these materials alone or a combination of two or more.

[0059] The thickness of the inorganic oxide layer 40 is preferably 1 to 200 nm. If the thickness is 1 nm or more, excellent oxygen barrier properties and water vapor barrier properties can be obtained. If the thickness is 200 nm or less, manufacturing costs can be kept low, and cracks caused by external forces such as bending and pulling are less likely to occur, thus suppressing deterioration of barrier properties.

[0060] The inorganic oxide layer 40 can be formed by known film deposition methods such as vacuum deposition, sputtering, ion plating, or plasma vapor deposition (CVD).

[0061] <Oxygen barrier coating> The oxygen barrier film 20 may be a known oxygen barrier film formed by a wet coating method. The oxygen barrier film 20 is obtained by forming a coating film made of a coating agent on a substrate layer 30 or an inorganic oxide layer 40 by a wet coating method, and then drying this coating film. Note that the coating film is a wet film, and the film is a dry film.

[0062] The oxygen barrier coating 20 is preferably a coating (organic-inorganic composite coating) containing at least one of a metal alkoxide and its hydrolysate, or its reaction product, and a water-soluble polymer. Furthermore, a coating containing at least one of a silane coupling agent and its hydrolysate is even more preferable.

[0063] Examples of metal alkoxides and their hydrolysates contained in organic-inorganic composite films include those represented by the general formula M(OR)n, such as tetraethoxysilane [Si(OC2H5)4] and triisopropoxyaluminum [Al(OC3H7)3], and their hydrolysates. One of these may be included alone, or two or more may be included in combination.

[0064] In an organic-inorganic composite film, the total content of at least one of metal alkoxides and their hydrolysates, or their reaction products, is, for example, 40 to 70% by mass. From the viewpoint of further reducing oxygen permeability, the lower limit of the total content of at least one of metal alkoxides and their hydrolysates, or their reaction products, in an organic-inorganic composite film may be 50% by mass. From a similar viewpoint, the upper limit of the total content of at least one of metal alkoxides and their hydrolysates, or their reaction products, in an organic-inorganic composite film may be 65% by mass.

[0065] The water-soluble polymers included in the organic-inorganic composite membrane are not particularly limited, and examples include polyvinyl alcohol-based polymers, polysaccharides such as starch, methylcellulose, and carboxymethylcellulose, and acrylic polyol-based polymers. From the viewpoint of further improving oxygen gas barrier properties, it is preferable that the water-soluble polymers include polyvinyl alcohol-based polymers. The number-average molecular weight of the water-soluble polymers is, for example, 40,000 to 180,000.

[0066] Polyvinyl alcohol-based water-soluble polymers can be obtained, for example, by saponifying (including partial saponification) polyvinyl acetate. These water-soluble polymers may contain several tens of percent of acetate groups, or they may contain only a few percent of acetate groups.

[0067] The content of water-soluble polymers in the organic-inorganic composite membrane is, for example, 15 to 50% by mass. The lower limit of the content of water-soluble polymers in the organic-inorganic composite membrane may be 20% by mass from the viewpoint of further reducing oxygen permeability. The upper limit of the content of water-soluble polymers in the organic-inorganic composite membrane may be 45% by mass from the viewpoint of further reducing oxygen permeability.

[0068] Examples of silane coupling agents and their hydrolysates included in organic-inorganic composite films include silane coupling agents having organic functional groups. Examples of such silane coupling agents and their hydrolysates include ethyltrimethoxysilane, vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidooxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and their hydrolysates. One of these may be included alone, or two or more may be included in combination.

[0069] It is preferable that at least one of the silane coupling agent and its hydrolysate has an epoxy group as an organic functional group. Examples of silane coupling agents having an epoxy group include γ-glycidooxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The silane coupling agent having an epoxy group and its hydrolysate may also have an organic functional group other than the epoxy group, such as a vinyl group, an amino group, a methacrylic group, or a ureyl group.

[0070] Silane coupling agents having organic functional groups and their hydrolysates can further improve the oxygen barrier properties of the oxygen barrier film 20 and its adhesion to the substrate layer 30 or inorganic oxide layer 40 through the interaction of their organic functional groups with the hydroxyl groups of water-soluble polymers. In particular, the interaction between the epoxy groups of the silane coupling agent and its hydrolysates and the hydroxyl groups of polyvinyl alcohol can form an oxygen barrier film 20 that exhibits particularly excellent oxygen barrier properties and adhesion to the substrate layer 30 or inorganic oxide layer 40.

[0071] In an organic-inorganic composite membrane, the total content of at least one of the silane coupling agent and its hydrolysate, or its reaction product, is, for example, 1 to 15% by mass. From the viewpoint of further reducing oxygen permeability, the lower limit of the total content of at least one of the silane coupling agent and its hydrolysate, or its reaction product, in the organic-inorganic composite membrane may be 2% by mass. From a similar viewpoint, the upper limit of the total content of at least one of the silane coupling agent and its hydrolysate, or its reaction product, in the organic-inorganic composite membrane may be 12% by mass.

[0072] The organic-inorganic composite film may contain crystalline inorganic layered compounds having a layered structure. Examples of inorganic layered compounds include clay minerals such as kaolinite, smectite, or mica minerals. These may be used individually or in combination of two or more. The particle size of the inorganic layered compound is, for example, 0.1 to 10 μm. The aspect ratio of the inorganic layered compound is, for example, 50 to 5000.

[0073] As inorganic layered compounds, smectite clay minerals are preferred because they can form a film with excellent oxygen barrier properties and adhesion strength through intercalation of water-soluble polymers between the layers of the layered structure. Specific examples of smectite clay minerals include montmorillonite, hectorite, saponite, and water-swellable synthetic mica.

[0074] Another preferred example of the oxygen barrier film 20 is a film containing a polyvalent metal salt of carboxylic acid, which is a reaction product of the carboxyl group of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B) (polycarboxylic acid polyvalent metal salt film). In this case, the polycarboxylic acid polyvalent metal salt film may be formed by applying and heating a coating agent which is a mixture of the polycarboxylic acid polymer (A) and the polyvalent metal compound (B), or it may be a polycarboxylic acid polyvalent metal salt film formed by applying and drying a coating agent mainly composed of the polycarboxylic acid polymer (A) to form film A, then applying and drying a coating agent mainly composed of the polyvalent metal compound (B) to form film B, and then crosslinking the A / B layers.

[0075] [Polycarboxylic acid polymer (A)] Polycarboxylic acid polymers are polymers having two or more carboxyl groups in their molecule. Examples of polycarboxylic acid polymers include (co)polymers of ethylenically unsaturated carboxylic acids; copolymers of ethylenically unsaturated carboxylic acids with other ethylenically unsaturated monomers; and acidic polysaccharides having carboxyl groups in their molecule, such as alginic acid, carboxymethylcellulose, and pectin. Examples of ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of ethylenically unsaturated monomers copolymerizable with ethylenically unsaturated carboxylic acids include ethylene, propylene, vinyl acetate and other saturated vinyl carboxylic acid esters, alkyl acrylates, alkyl methacrylates, alkyl itaconates, vinyl chloride, vinylidene chloride, styrene, acrylamide, and acrylonitrile. These polycarboxylic acid polymers may be used individually or in combination of two or more types.

[0076] As for the components, from the viewpoint of the gas barrier properties of the resulting gas barrier film 1, a polymer containing a structural unit derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid, and crotonic acid is preferred, and a polymer containing a structural unit derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, and itaconic acid is particularly preferred. In the polymer, the proportion of structural units derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, and itaconic acid is preferably 80 mol% or more, and more preferably 90 mol% or more (provided that the total of all structural units constituting the polymer is 100 mol%). The polymer may be a homopolymer or a copolymer. If the polymer is a copolymer containing structural units other than the above structural units, examples of such other structural units include structural units derived from ethylenically unsaturated monomers copolymerizable with the aforementioned ethylenically unsaturated carboxylic acids.

[0077] The number-average molecular weight of the polycarboxylic acid polymer is preferably in the range of 2,000 to 10,000,000, and more preferably in the range of 5,000 to 1,000,000. If the number-average molecular weight is less than 2,000, the resulting gas barrier film may not achieve sufficient water resistance, and moisture may cause deterioration of gas barrier properties and transparency, or whitening may occur. On the other hand, if the number-average molecular weight exceeds 10,000,000, the viscosity of the coating agent used to form the oxygen barrier film 20 increases, which may impair the coating properties. The above number-average molecular weight is the polystyrene-converted number-average molecular weight determined by gel permeation chromatography (GPC).

[0078] When a coating agent mainly composed of a polycarboxylic acid polymer (A) is applied and dried to form film A, and then film B is formed, some of the carboxyl groups of the polycarboxylic acid polymer may be neutralized in advance with a basic compound. By neutralizing some of the carboxyl groups of the polycarboxylic acid polymer in advance, the water resistance and heat resistance of film A can be further improved. As the basic compound, at least one basic compound selected from the group consisting of polyvalent metal compounds, monovalent metal compounds, and ammonia is preferred. As the polyvalent metal compound, compounds exemplified in the description of polyvalent metal compound (B) described later can be used. Examples of monovalent metal compounds include sodium hydroxide and potassium hydroxide.

[0079] Various additives can be added to coating agents mainly composed of polycarboxylic acid polymers (A), and these include crosslinking agents, curing agents, leveling agents, defoaming agents, antiblocking agents, antistatic agents, dispersants, surfactants, softeners, stabilizers, film-forming agents, and thickeners, as long as they do not impair the barrier performance.

[0080] A solvent is preferred for coating agents mainly composed of a polycarboxylic acid polymer (A). Examples of aqueous media include water, water-soluble or hydrophilic organic solvents, or mixtures thereof. Aqueous media are usually water or mainly composed of water. The water content in the aqueous media is preferably 70% by mass or more, and more preferably 80% by mass or more. Examples of water-soluble or hydrophilic organic solvents include alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; cellosolves; carbitols; and nitriles such as acetonitrile.

[0081] [Polyvalent metal compounds (B)] The polyvalent metal compound is not particularly limited as long as it is a compound that reacts with the carboxyl group of the polycarboxylic acid polymer to form a polyvalent metal salt of the polycarboxylic acid, and examples include zinc oxide particles, magnesium oxide particles, magnesium methoxide, copper oxide, and calcium carbonate. These may be used individually or in combination. Zinc oxide is preferred from the viewpoint of the oxygen barrier properties of the oxygen barrier film.

[0082] Zinc oxide is an inorganic material with ultraviolet absorption capabilities. While the average particle size of zinc oxide particles is not particularly limited, from the viewpoint of gas barrier properties, transparency, and coating suitability, an average particle size of 5 μm or less is preferred, more preferably 1 μm or less, and particularly preferred to be 0.1 μm or less.

[0083] When a coating agent mainly composed of a polyvalent metal compound (B) is applied and dried to form a film, various additives may be included in addition to zinc oxide particles as needed, to the extent that they do not impair the effects of the present disclosure. These additives may include resins soluble or dispersible in the solvent used in the coating agent, dispersants soluble or dispersible in the solvent, surfactants, softeners, stabilizers, film-forming agents, thickeners, and the like.

[0084] Among the above, it is preferable that the solvent used in the coating agent contains a resin that is soluble or dispersible in the solvent. This improves the coating properties and film-forming properties of the coating agent. Examples of such resins include alkyd resins, melamine resins, acrylic resins, urethane resins, polyester resins, phenolic resins, amino resins, fluororesins, epoxy resins, and isocyanate resins.

[0085] Furthermore, it is preferable to include a dispersant that is soluble in or dispersible in the solvent used in the coating agent. This improves the dispersibility of polyvalent metal compounds. Anionic surfactants or nonionic surfactants can be used as the dispersant. Examples of such surfactants include (poly)carboxylates, alkyl sulfates, alkylbenzene sulfons, alkylnaphthalene sulfons, alkyl sulfosuccinates, alkyl diphenyl ether disulfons, alkyl phosphates, aromatic phosphates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, alkyl allyl sulfates, polyoxyethylene alkyl phosphates, sorbitan alkyl esters, glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene sorbitan alkyl esters, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, polyoxyethylene sorbitol fatty acid esters, polyoxy fatty acid esters, and polyoxyethylene alkylamines. These surfactants may be used individually or in combination of two or more.

[0086] When a coating agent mainly composed of a polyvalent metal compound (B) contains an additive, the mass ratio of the polyvalent metal compound to the additive (polyvalent metal compound:additive) is preferably in the range of 30:70 to 99:1, and preferably in the range of 50:50 to 98:2.

[0087] Examples of solvents used in coating agents mainly composed of polyvalent metal compounds (B) include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used individually or in combination of two or more. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of coating properties. Furthermore, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred from the viewpoint of manufacturability.

[0088] When forming a polyvalent metal salt film of polycarboxylic acid by applying and drying a coating agent which is a mixture of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B), the polycarboxylic acid polymer (A) and the polyvalent metal compound (B) can be mixed with water or alcohols as a solvent, along with a resin or dispersant that can dissolve or disperse in the solvent, and additives as needed, to form a coating agent which can then be applied and dried using a known coating method to form a polyvalent metal salt film of polycarboxylic acid. Examples of coating methods include the casting method, dipping method, roll coating method, gravure coating method, screen printing method, reverse coating method, spray coating method, kit coating method, die coating method, metering bar coating method, chamber doctor combined coating method, and curtain coating method.

[0089] The thickness of the oxygen barrier film 20 is set according to the required oxygen barrier properties, and may be, for example, 0.05 to 5 μm. Preferably, the thickness of the oxygen barrier film 20 is 0.05 to 1 μm, and more preferably 0.1 to 0.5 μm. If the thickness of the oxygen barrier film 20 is 0.05 μm or more, sufficient oxygen barrier properties are easily obtained. If the thickness of the oxygen barrier film 20 is 1 μm or less, it is easy to form a uniform coated surface, drying load and manufacturing costs can be reduced, and the usefulness of using a resin substrate 10 having a surface with a black area ratio of 0.15% or less, which is a feature of this disclosure, becomes more apparent.

[0090] As the oxygen barrier coating 20, the gas barrier film having the aforementioned organic-inorganic composite coating or the aforementioned polyvalent metal salt coating of polycarboxylic acid exhibits excellent oxygen barrier properties even after boiling or retort sterilization. When laminated with a sealant film, it has sufficient adhesion and sealing strength as a packaging material for boiling and retort processing. Furthermore, it has advantages such as transparency not found in metal foils or metal vapor-deposited films, excellent bending and stretching resistance, and no risk of generating harmful substances such as dioxins.

[0091] [Method for manufacturing gas barrier film] The gas barrier film 1 can be manufactured by forming a base layer 30, an inorganic oxide layer 40, or both the base layer 30 and the inorganic oxide layer 40 on one side 12 of a resin substrate 10, and then forming an oxygen barrier film 20 on the base layer 30 or the inorganic oxide layer 40.

[0092] A method for manufacturing the gas barrier film 1 of this disclosure includes, for example, a sorting step, a base layer formation step, an inorganic oxide layer formation step, and an oxygen barrier film formation step.

[0093] One example of a sorting process is to sort resin substrate raw materials with a surface black area ratio of 0.15% or less as resin substrates. The surface black area ratio of the resin substrate raw material is measured in the same way as the method for measuring the black area ratio of one side 12 of the resin substrate 10 described above.

[0094] The resin substrate 10 may be a commercially available product or one manufactured by a known method.

[0095] The base layer formation process includes, for example, a step of applying a coating agent to at least one surface 12 of a resin substrate 10 by a wet coating method to form a coating film, and then forming a base layer 30 by drying the coating film (removing the solvent).

[0096] As a method for applying the coating agent, known wet coating methods can be used. Examples of wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating.

[0097] As a method for drying the coating film made of the coating agent, known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used. The drying temperature of the coating film is preferably, for example, 50 to 200°C. The drying time varies depending on the thickness of the coating film, the drying temperature, etc., but is preferably, for example, 1 second to 5 minutes.

[0098] The inorganic oxide layer formation process includes, for example, a step of forming an inorganic oxide layer 40 on one surface 12 of the resin substrate 10 or on the underlayer 30 by the vacuum deposition method, sputtering method, ion plating method, or plasma vapor deposition (CVD) method described above.

[0099] An oxygen barrier film formation process may include, for example, a step of applying a coating agent to a base layer 30 or an inorganic oxide layer 40 by a wet coating method to form a coating film, and then drying the coating film (removing the solvent) to form an oxygen barrier film 20.

[0100] As a method for applying the coating agent, known wet coating methods can be used. Examples of wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating.

[0101] As a method for drying the coating film made of the coating agent, known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used. The drying temperature of the coating film is preferably, for example, 50 to 200°C. The drying time varies depending on the thickness of the coating film, the drying temperature, etc., but is preferably, for example, 1 second to 5 minutes.

[0102] The oxygen barrier film 20 may be formed by a single application and drying, or by repeating the application and drying process multiple times using the same type of coating agent or different types of coating agents.

[0103] In the underlayer formation process, the inorganic oxide layer formation process, and the oxygen barrier film formation process, the underlayer 30, the inorganic oxide layer 40, or the oxygen barrier film 20 is formed on one surface 12 of the resin substrate 10. At this time, the black area ratio of the one surface 12 is 0.15% or less. Furthermore, the underlayer 30, the inorganic oxide layer 40, or the oxygen barrier film 20 may be formed on both surfaces of the resin substrate 10. In that case, the black area ratio of the other surface 14 of the resin substrate 10 is 0.15% or less.

[0104] When a base layer 30, an inorganic oxide layer 40, or an oxygen barrier coating 20 is formed on both surfaces of the resin substrate, it is preferable that the black area ratio on both surfaces of the resin substrate is 0.15% or less, as this enhances the oxygen barrier properties and improves printability.

[0105] When the method for manufacturing the gas barrier film 1 of this disclosure includes a sorting step, resin substrates with a surface black area ratio of 0.15% or less can be efficiently applied. Therefore, by including a sorting step, a gas barrier film 1 with improved oxygen barrier properties can be efficiently manufactured. In addition, by including a sorting step, a gas barrier film 1 with good printability can be efficiently manufactured.

[0106] The gas barrier film 1 of this disclosure may further include, as necessary, a printed layer, a protective layer, a light-shielding layer, an adhesive layer, a heat-sealable heat-sealable layer, or other functional layers.

[0107] If the gas barrier film 1 of this disclosure has a heat-sealable heat-sealable layer, this heat-sealable layer is disposed on at least one of the outermost layers of the gas barrier film 1. The presence of the heat-sealable layer in the gas barrier film 1 makes the gas barrier film 1 heat-sealable (for example, a package or a lid).

[0108] The heat-sealable layer can be laminated, for example, to a laminate obtained by forming the base layer 30, inorganic oxide layer 40, and oxygen barrier film 20 of this embodiment on one or both sides of a resin substrate, using a known adhesive such as a polyurethane-based, polyester-based, or polyether-based adhesive, by a known dry lamination method, extrusion lamination method, or the like.

[0109] <Effects and Effects> The gas barrier film 1 of this disclosure binarizes the brightness in a monochrome image and measures 100 μm 2 The total area ratio (black area ratio) of the black regions of the above size is calculated. An oxygen barrier film 20 is laminated on at least one surface of a resin substrate 10 having a black area ratio of 0.15% or less, via a base layer 30, an inorganic oxide layer 40, or both the base layer 30 and the inorganic oxide layer 40.

[0110] The gas barrier film 1 of this disclosure has an oxygen barrier film 20 formed on the surface of a resin substrate 10 having a black area ratio of 0.15% or less, via a base layer 30, an inorganic oxide layer 40, or both. Therefore, film defects caused by large protrusions on the substrate surface are less likely to occur, and the oxygen barrier properties are easier to improve. In addition, the printability of the gas barrier film 1 is easier to improve.

[0111] Therefore, by using the gas barrier film 1 of this disclosure as a packaging material, the quality preservation of the contents can be improved at a low cost.

[0112] In addition, by using the gas barrier film 1 of this disclosure as a packaging material, printing can be easily and beautifully applied.

[0113] (Embodiment 2) As described above, gas barrier films, which are formed by applying a coating to the surface of a resin substrate using methods such as wet coating, vapor deposition, or sputtering, sometimes exhibited inconsistent oxygen barrier properties depending on the manufacturing lot. Specifically, the oxygen barrier properties of the gas barrier film were sometimes inferior to the intended oxygen barrier properties, that is, the oxygen barrier properties expected from the materials constituting the coating and the thickness of the coating. This problem tended to occur more easily when the thickness of the coating was thin. As a result, it was necessary to increase the thickness of the gas barrier layer more than necessary, which led to problems with poor productivity and excessive material costs.

[0114] Furthermore, while polyolefin resin films are inexpensive and have high water vapor barrier properties, making them commonly used as packaging materials, they have the drawback of poor adhesion to gas barrier coatings. This results in inferior laminate strength when laminated with heat-sealable resin films to create gas barrier packaging materials.

[0115] Embodiment 2 aims to provide a gas barrier film and a method for manufacturing the same, which exhibits excellent gas barrier properties by fully demonstrating its inherent oxygen barrier properties even with a thin coating thickness for imparting oxygen barrier properties, and which also has sufficient adhesion strength as a packaging material.

[0116] To investigate the cause of the aforementioned problem, the inventors observed the surface and cross-section of a gas barrier film with poor oxygen barrier properties in detail using an optical microscope and an electron microscope. Cross-sectional electron microscopy observation using a focused ion / electron beam processing observation device revealed that defects several μm wide occurred in the film at locations where the antiblocking agent (hereinafter also referred to as "AB agent") added to prevent blocking of the resin substrate was present. (An example of a cross-sectional electron microscope image is shown in Figure 8.) It is thought that these film defects became pathways for gas permeation, preventing the oxygen barrier properties from being fully realized. The surface of the resin substrate has protrusions of various sizes due to the AB agent. There are variations in the protrusion height and density of the AB agent depending on the manufacturing lot of the resin substrate, and it is thought that when a gas barrier film (oxygen barrier film) was coated on the surface of the resin substrate, the film was not locally formed at the locations of the large protrusions, resulting in defects and unstable oxygen barrier properties.

[0117] Therefore, the present inventors have devised a method to accurately grasp the wide-ranging surface condition of a resin substrate that affects the oxygen barrier properties of a gas barrier film in a short amount of time, and have come to this disclosure.

[0118] [1] The material comprises a resin substrate and an oxygen barrier coating formed on one side of the resin substrate, which is the first surface, and at least one of a base layer and an inorganic oxide layer is between the resin substrate and the oxygen barrier coating, the resin substrate has two or more resin layers, of which the resin layer forming the first surface is made of a polyolefin copolymer resin, and the first surface has 20 or more protrusions / mm² with a ferret diameter of 8 μm or more as measured by the measurement method described below. 2 The following is a gas barrier film. <Measurement method> A white LED line light source is used to illuminate an arbitrary 36.6 mm square area on the first surface of a resin substrate at a light source distance of 100 mm and an incident angle of 83°. The transmitted light at a measurement angle of 90° is captured by a monochrome line camera to obtain an image. A 3551 x 5684 pixel (2.5 x 4.0 mm) analysis image is extracted from the captured image, and protrusions with a ferret diameter of 8 μm or more in the analysis image are counted.

[0119] [2] A gas barrier film in which the resin substrate is a polyolefin resin.

[0120] [3] A gas barrier film having a thickness of 0.01 to 1 μm in the underlying layer.

[0121] [4] The substrate is a gas barrier film comprising an organic polymer as its main component, wherein the organic polymer comprises at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers.

[0122] [5] A gas barrier film having an inorganic oxide layer thickness of 1 to 200 nm.

[0123] [6] A gas barrier film in which the inorganic oxide layer is aluminum oxide or silicon oxide.

[0124] [7] A gas barrier film having an oxygen barrier coating thickness of 0.05 to 1 μm.

[0125] [8] The oxygen barrier film comprises a metal alkoxide, a hydrolysate of a metal alkoxide, and at least one of the reaction products of a metal alkoxide or a hydrolysate of a metal alkoxide. A gas barrier film that is a coating containing a water-soluble polymer.

[0126] [9] A gas barrier film wherein the oxygen barrier film further comprises a silane coupling agent, a hydrolysis product of a silane coupling agent, and at least one of the reaction products of a silane coupling agent or a hydrolysis product of a silane coupling agent.

[0127]

[10] A gas barrier film wherein the oxygen barrier film contains a polyvalent metal salt of a carboxylic acid, which is a reaction product of a carboxyl group of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B).

[0128] A method for manufacturing a gas barrier film according to any one of items

[11] [1] to

[10] , wherein the number of protrusions on one side of the resin substrate raw material is measured by the following measurement method, and the number of protrusions with a ferret diameter of 8 μm or more is 20 per mm. 2 A method for manufacturing a gas barrier film, comprising the steps of: using the following resin substrate raw material as the resin substrate; and applying a coating agent to at least the first surface of the resin substrate to form an oxygen barrier film. <Measurement method> A white LED line light source is used to illuminate an arbitrary 36.6 mm square area on the first surface of a resin substrate at a light source distance of 100 mm and an incident angle of 83°. The transmitted light at a measurement angle of 90° is captured by a monochrome line camera to obtain an image. A 3551 x 5684 pixel (2.5 x 4.0 mm) analysis image is extracted from the captured image, and protrusions with a ferret diameter of 8 μm or more in the analysis image are counted.

[0129] The gas barrier film of this disclosure will be described with reference to embodiments. Figure 4 is a schematic cross-sectional view of a gas barrier film 101 according to Embodiment 2. The dimensional ratios in Figure 4 differ from those of the actual dimensions for the sake of explanation. The gas barrier film 101 has a resin substrate 120, a base layer 140, an inorganic oxide layer 150, and an oxygen barrier film 130. Either the base layer 140 or the inorganic oxide layer 150 may be omitted. The base layer 140 is laminated in contact with the first surface 21 of the resin substrate 120, and the inorganic oxide layer 150 is laminated on the opposite side of the base layer 140 from the surface in contact with the resin substrate 120. The inorganic oxide layer 150 is laminated in contact with the base layer 140, and the oxygen barrier film 130 is located in contact with the opposite side of the inorganic oxide layer 150 from the surface in contact with the base layer 140. If the base layer 140 is not provided, the inorganic oxide layer 150 is laminated on the first surface 21 of the resin substrate 120. Also, if the inorganic oxide layer 150 is not provided, the oxygen barrier film 130 is laminated on the base layer 140.

[0130] <Resin substrate> The resin substrate 120 has two or more resin layers, including a base layer 25. In this embodiment, it has a base layer 25 and a surface layer 23 located on one surface of the base layer 25. The surface layer 23 constitutes the first surface 21 of the resin substrate 120. The resin substrate 120 contains resin, and each layer constituting the resin substrate 120, the surface layer 23 and the base layer 25, also contains resin.

[0131] The base layer 25 adjusts the mechanical, chemical, thermal, and optical properties of the resin substrate 120. Mechanical properties include rigidity, elongation, stiffness, tear strength, impact strength, puncture strength, and pinhole resistance. Chemical properties include water vapor barrier properties, gas barrier properties, fragrance retention, chemical resistance, and oil resistance. Thermal properties include melting point, glass transition temperature, heat resistance temperature, cold resistance temperature, and thermal shrinkage rate. Optical properties include transparency and gloss.

[0132] Polyolefin resins are preferred as the raw material for the base layer 25 from the viewpoint of ease of availability and water vapor barrier properties. Examples of polyolefin resins include polyethylene, polypropylene, and polybutene. Polypropylene may be a homopolymer, random copolymer, or block copolymer. A homopolymer is polypropylene consisting only of propylene. A random copolymer is polypropylene in which propylene, the main monomer, and a different type of comonomer are randomly copolymerized to form a homogeneous phase. A block copolymer is polypropylene in which propylene, the main monomer, and the above comonomers copolymerize in a block-like manner or polymerize into a rubbery state to form a heterogeneous phase. These polyolefin resins may be used individually or blended together.

[0133] The base layer 25 may contain additives. These additives can be appropriately selected from a variety of known additives. Examples of additives include fillers, antiblocking agents (AB agents), heat stabilizers, weather stabilizers, UV absorbers, lubricants, slip agents, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes. These additives may be used individually or in combination of two or more. The content of the additives in the base layer 25 can be appropriately adjusted within a range that does not impede the effects of this disclosure.

[0134] The base layer 25 may be a single-layer or multi-layer structure. The thickness of the base layer 25 may be, for example, 3 to 200 μm or 6 to 30 μm.

[0135] The surface layer 23 is composed of a polyolefin copolymer resin. Examples of polyolefin copolymer resins include ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, propylene-pentene copolymer, ethylene-propylene-1-butene copolymer, ethylene-acrylic acid copolymer, ionomers obtained by crosslinking ethylene-acrylic acid copolymer with metal ions, and propylene-acrylic acid copolymer, and each can be either a random copolymer or a block copolymer. These resins may be used individually or blended from two or more types. Because the surface layer 23 is composed of a polyolefin copolymer resin, good adhesion is achieved to any of the underlayer 140, inorganic oxide layer 150, and oxygen barrier film 130 laminated on the resin substrate 120.

[0136] The surface layer 23 may contain additives. These additives can be appropriately selected from a variety of known additives. Examples of additives include antiblocking agents (AB agents), heat stabilizers, weather stabilizers, UV absorbers, lubricants, slip agents, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes. These additives may be used individually or in combination of two or more. The content of the additives in the surface layer 23 can be appropriately adjusted within a range that does not impede the effects of this disclosure.

[0137] When the surface layer 23 contains the AB agent, protrusions derived from the AB agent are formed on the first surface 21 of the resin substrate 120. These protrusions prevent the adhesion of the films to each other, improving the processing suitability in winding, unwinding, and conveying the film web. In particular, since the average particle diameter and the addition amount of the AB agent affect the size and number of the protrusions on the first surface 21, it is desirable to adjust them so that the number of protrusions with a Feret diameter of 8 μm or more is 20 per mm in the measurement method described below. 2 It is desirable to adjust them as follows.

[0138] The AB agent is solid particles, and examples include organic particles and inorganic particles. Examples of the organic particles include polymethyl methacrylate particles, polystyrene particles, and polyamide particles. These organic particles can be obtained, for example, by emulsion polymerization or suspension polymerization. Examples of the inorganic particles include silica particles, zeolite, talc, kaolinite, and feldspar. Any one of these AB agents may be used alone, or two or more of them may be used in combination. As the AB agent, polymethyl methacrylate particles are preferable for the organic type, and silica particles are preferable for the inorganic type.

[0139] The average particle diameter of the AB agent is preferably 0.1 μm or more and 5 μm or less. From the viewpoint of achieving both the blocking prevention performance and the gas barrier performance of the gas barrier film 101, the average particle diameter of the AB agent is particularly preferably 1 μm or more and 4 μm or less. The average particle diameter of the AB agent is measured by the Coulter method.

[0140] The addition amount of the AB agent is preferably 0.05 to 0.4% by mass based on the total mass of the surface layer 23. Specifically, the addition amount of the AB agent in the surface layer 23 is determined by the following formula. Addition amount of AB agent [% by mass] = {(i) / 100} × {(ii) / 100} × 100 In the formula, (i) refers to the concentration (mass%) of the AB agent in the masterbatch resin chip, which is formed into pellets by melt extrusion after adding the AB agent to the resin, stirring, and mixing in an extruder. (ii) refers to the concentration (mass%) of the masterbatch resin chip containing the AB agent relative to the total mass of resin pellets constituting the surface layer 23 when the masterbatch resin chip containing the AB agent is blended with a resin that does not contain the AB agent. Similarly, when adding the AB agent to the base layer 25, the amount added is preferably 0.05 to 0.4 mass% relative to the total mass of the base layer 25, and the amount added can be determined by the above formula.

[0141] The thickness of the surface layer 23 may be, for example, 0.1 to 10 μm, and moreover, 0.5 to 5.0 μm.

[0142] The resin substrate 120 is preferably a co-extruded film comprising at least a surface layer 23 and a base layer 25. The resin substrate 120 may be a stretched film or an unstretched film.

[0143] The resin substrate 120 preferably has a biaxially oriented polypropylene film. Since biaxially oriented polypropylene films have particularly excellent water vapor barrier properties, the presence of a biaxially oriented polypropylene film improves the water vapor barrier properties of the gas barrier film 101. The biaxially oriented polypropylene film may be a film made by processing at least one of the following into a film: a homopolymer, a random copolymer, a block copolymer, etc. The biaxially oriented polypropylene film is preferably a co-extruded film.

[0144] The base layer 25 may consist of a biaxially oriented polypropylene film, or it may be a laminate of a biaxially oriented polypropylene film and another resin film. Examples of other resin films include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyolefin resin films such as polyethylene, polystyrene films, polyamide films such as nylon, polycarbonate films, polyacrylonitrile films, and engineering plastic films such as polyimide films.

[0145] The thickness of the resin substrate 120 is not particularly limited and is selected appropriately depending on the price and application, taking into consideration its suitability as a packaging material and its suitability for lamination of other coatings. In practical terms, the thickness of the resin substrate 120 is preferably 3 μm to 200 μm, more preferably 5 μm to 120 μm, and even more preferably 6 μm to 30 μm.

[0146] The first surface 21 of the resin substrate 120 may be subjected to at least one treatment selected from the group consisting of chemical treatment, solvent treatment, corona treatment, plasma treatment, and ozone treatment.

[0147] When protrusions are formed on the first surface 21 of the resin substrate 120 by the AB agent, blocking of the film can be prevented. However, in large protrusions, film defects that serve as pathways for gas permeation are more likely to occur in the underlying layer 140, inorganic oxide layer 150, and oxygen barrier coating 130 formed thereon, potentially reducing the oxygen barrier properties of the gas barrier film 101. However, the first surface 21 of the resin substrate 120 of the gas barrier film 101 of this disclosure has 20 protrusions / mm² with a Ferret diameter of 8 μm or more, as measured by the measurement method described below. 2 The following characteristics make it less prone to film defects: The first surface 21 of the resin substrate 120 has 17 protrusions / mm² with a Ferret diameter of 8 μm or more. 2 More preferably, there are 15 protrusions / mm² with a ferret diameter of 8 μm or more. 2 More preferably, the following conditions are met: 0 protrusions / mm² with a diameter of 8 μm or more. 2This is acceptable. Many protrusions with a ferret diameter of 8 μm or more have a height exceeding 1 μm from the flat area of ​​the first surface 21 to the tip of the protrusion, which makes them prone to causing film defects in the oxygen barrier coating. Therefore, if there are 20 protrusions with a ferret diameter of 8 μm or more per mm 2 The following conditions make it less likely for film defects to occur in the underlayer 140, the inorganic oxide layer 150, and the oxygen barrier coating 130, thus making it easier to improve the oxygen barrier properties of the gas barrier film 101. The protrusions formed on the first surface 21 of the resin substrate 120 may be derived from the AB agent or from other factors, and are not particularly limited. In this specification, the number of protrusions on the first surface 21 of the resin substrate 120 is a value measured by the following measurement method.

[0148] <Measurement method> A white LED line light source is used to illuminate an arbitrary 36.6 mm square area of ​​the resin substrate 120 from the second surface 22, which is the opposite side of the first surface 21 of the resin substrate 120, at a light source distance of 100 mm and an incident angle of 83°. The transmitted light at a measurement angle of 90° is captured by a monochrome line camera to obtain an image. From the acquired image, an analysis image of 3551 pixels × 5684 pixels (2.5 × 4.0 mm) is extracted. Image analysis software is used to extract protrusions with a Ferret diameter of 8 μm or more from the extracted analysis image and count their number. 2 Converted to a unit, this is the number of protrusions with a diameter of 8 μm or more.

[0149] The method for measuring the number of protrusions on the first surface 21 of the resin substrate 120 will be described below with reference to the drawings. First, the measuring apparatus will be described.

[0150] (Measuring device) As shown in Figure 5, the measuring device 15 for measuring the number of protrusions on the first surface 21 of the resin substrate 120 comprises a sample holder 2, a light source 4, and a monochrome line camera 7. The sample holder 2 is mounted on a transport device 16 and can move horizontally. A hole 3 is formed in the center of the sample holder 2. The light source 4 is located below the sample holder 2, at a light source distance of 100 mm, and is connected to a light source control device 6. The monochrome line camera 7 is located above the sample holder 2, and is fitted with a macro lens 8. An image processing device 9 is connected to the monochrome line camera 7. A transport control unit 17 is connected to the image processing device 9. The transport control unit 17 is connected to the transport device 16.

[0151] The sample holder 2 is not particularly limited as long as it is flat and horizontal, and any known holder may be used. A visible white LED line light source is preferred as the light source 4.

[0152] It is preferable to use a monochrome line camera 7 with 16,384 pixels and a sensor size of 3.52 μm per pixel. It is preferable that the monochrome line camera 7 is controlled by the image processing device 9 via an interface such as Camera Link or USB. The image processing device 9 consists of, for example, a personal computer equipped with a frame grabber connected to the monochrome line camera 7, and image processing software that controls the frame grabber. Personal computers equipped with frame grabbers and image processing software that controls the frame grabber are widely distributed or commercially available, and these can be used as the image processing device 9. An example of image processing software is "ImageJ," public domain software developed by the National Institutes of Health (NIH) in the United States.

[0153] The conveying device 16 preferably uses a single-axis stage driven by a stepping motor. The conveying device 16 is controlled by the conveying control unit 17, which controls the conveying speed, conveying start, conveying stop, etc.

[0154] (Sample preparation) Next, the method for measuring the number of protrusions on the first surface of the resin substrate 120 will be described. As shown in Figure 5, first, the resin substrate 120 is fixed to the sample holder 2 with its first surface 21 facing the monochrome line camera 7, so that no height difference occurs within the surface. When fixing the resin substrate 120, it is preferable to fix the ends of the resin substrate 120 using OPP tape or masking tape. The resin substrate 120 is fixed to the sample holder 2 so that the image measurement position 18 of the resin substrate 120 aligns with the cutout hole 3.

[0155] (Acquisition of captured images) Next, white LED line light is incident from light source 4. The light intensity of light source 4 can be adjusted by light source control device 6. Preferably, the light intensity of incident light L1 is adjusted using light source control device 6 so that the light intensity at image measurement position 18 is 442 lux. The incident light L1 from light source 4 is positioned so that the incident angle 13 with respect to the first surface 21 is 83°, and it is shifted 7° diagonally from the vertical, so that the measurement angle 19 with respect to the first surface 21 is 90°. A monochrome line camera 7 is then installed at this position, and the transmitted light L2 that has passed through image measurement position 18 is captured by the monochrome line camera 7 through a macro lens 8. At this time, the magnification of the macro lens 8 is set to 5x, the F value to 2.8, and the resolution to 0.704 μm. The measurement range of the monochrome line camera 7 at image measurement position 18 is a 36.6 mm square area, and the effective illumination range of light source 4 is greater than or equal to a 36.6 mm square area.

[0156] The measurement range of transmitted light L2 is a 36.6 mm square area on the first surface 21. The transport device 16 is moved so that the measurement range is the above area. If the transport device 16 is a stepping motor or the like, a pulse signal indicating the transport speed is acquired by the image processing device 9. It is preferable to set the transport speed for moving the transport device 16 to be equal to the product of the spatial resolution and the acquisition frequency. The spatial resolution is determined from the sensor size of the monochrome line camera 7 (3.52 μm) and the magnification of the macro lens 8 (5x). The acquisition frequency is the acquisition frequency of one line of the monochrome line camera 7. The transport speed is set to be equal to the product of the spatial resolution and the acquisition frequency, and the resin substrate 120 is continuously transported at the image measurement position 18 of the monochrome line camera 7. At the image measurement position 18, the image of the first surface 21 of the resin substrate 120 is measured and captured by the monochrome line camera 7.

[0157] The exposure time for the monochrome line camera 7 is set to 80 μs. The period of the acquisition frequency is set to be longer than the exposure time. The resin substrate 120 is transported, and an image with 5684 pixels or more is acquired in the transport direction of the resin substrate 120.

[0158] (Image analysis) In the acquired captured image, 3551 pixels in the center corresponding to the sensor alignment direction of the monochrome line camera 7 (perpendicular to the transport direction of the resin substrate 120) and 5684 pixels in the transport direction are extracted to create an image for analysis. It is also possible to extract more than 5684 pixels in the transport direction to widen the measurement range. The extracted image for analysis is then analyzed using image analysis software.

[0159] Figure 6 illustrates the principle by which this measurement system can detect minute protrusions and depressions on the surface of the resin substrate 120. When the incident angle θ2 is smaller than the measurement angle θ1 using a line camera, protrusions are visualized three-dimensionally, with the upper part of the image being brighter and the lower part darker. In depressions, the top and bottom are reversed. This is presumed to be due to refraction similar to that of a spherical lens. Using this tendency, bright and dark particles are sorted from the analysis image based on brightness, size, and roundness, respectively, and then binarized. Particles that are brighter at the top and darker at the bottom are extracted as protrusions, and the Ferret diameter data of the extracted particles is obtained. Figure 7 shows the captured image of the first surface 21 of the resin substrate 120 in the example, and the analysis image from which the protrusions have been extracted using the above algorithm. From the Ferret diameter data thus extracted, the number of particles with a Ferret diameter of 8 μm or more in the analysis image is counted, and the mm 2 The number of protrusions was calculated by converting the value to the number of protrusions per unit area.

[0160] <Underlayer> The underlayer 140 is provided between the resin substrate 120 and the inorganic oxide layer 150 or the oxygen barrier film 130. The underlayer 140 is a layer mainly composed of organic polymers and is sometimes called a primer layer. By providing the underlayer 140, the film-forming properties and adhesion strength of the inorganic oxide layer 150 or the oxygen barrier film 130 can be improved.

[0161] The content of organic polymers in the base layer 140 may be, for example, 70% by mass or more, or 80% by mass or more. Examples of organic polymers include polyacrylic resin, polyester resin, polycarbonate resin, polyurethane resin, polyamide resin, polyolefin resin, polyimide resin, melamine resin, and phenolic resin. Considering the adhesion strength between the resin substrate 120 and the inorganic oxide layer 150 or oxygen barrier film 130, and the resistance to hot water, it is preferable to include at least one of polyacrylic resin, polyol resin, polyurethane resin, polyamide resin, or reaction products of these organic polymers. The base layer 140 may also contain a silane coupling agent, organic titanate, or modified silicone oil.

[0162] More preferably, the organic polymers include organic polymers having urethane bonds produced by the reaction of polyols having two or more hydroxyl groups at the polymer ends with an isocyanate compound, and / or organic polymers containing reaction products of polyols having two or more hydroxyl groups at the polymer ends with an organic silane compound such as a silane coupling agent or its hydrolysate.

[0163] Examples of polyols include at least one selected from acrylic polyols, polyvinyl acetals, polysyl polyols, and polyurethane polyols. Acrylic polyols may be obtained by polymerizing acrylic acid derivative monomers, or by copolymerizing acrylic acid derivative monomers with other monomers. Examples of acrylic acid derivative monomers include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of monomers copolymerized with acrylic acid derivative monomers include styrene.

[0164] The isocyanate compound enhances the adhesion between the resin substrate 120 and the inorganic oxide layer 150 or oxygen barrier film 130 through urethane bonding formed by reaction with the polyol. In other words, the isocyanate compound functions as a crosslinking agent or curing agent. Examples of isocyanate compounds include monomers such as aromatic tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), aliphatic xylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), and isophorone diisocyanate (IPDI), polymers thereof, and derivatives thereof. The above-mentioned isocyanate compounds may be used individually or in combination of two or more.

[0165] Examples of silane coupling agents include vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidooxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. The organosilane compound may be a hydrolysate of these silane coupling agents. The organosilane compound may contain one of the above-mentioned silane coupling agents and their hydrolysates alone, or in combination of two or more.

[0166] The base layer 140 can be formed on the first surface 21 of the resin substrate 120 using a mixture prepared by blending the above-mentioned components in any proportion in an organic solvent. The mixture may contain, for example, curing accelerators such as tertiary amines, imidazole derivatives, metal salt compounds of carboxylic acids, quaternary ammonium salts, and quaternary phosphonium salts; antioxidants such as phenolic, sulfuric, and phosphite-based agents; leveling agents; flow regulators; catalysts; crosslinking reaction accelerators; fillers, etc.

[0167] The mixture can be coated onto the resin substrate 120 using a well-known printing method such as offset printing, gravure printing, or screen printing, or a well-known coating method such as roll coating, knife edge coating, or gravure coating. After coating, the substrate layer 140 can be formed by heating to, for example, 50-200°C and drying and / or curing.

[0168] The thickness of the underlayer 140 is not particularly limited and may be, for example, 0.005 to 5 μm. The thickness may be adjusted according to the application or required properties. The thickness of the underlayer 140 is preferably 0.01 to 1 μm, and more preferably 0.01 to 0.5 μm. If the thickness of the underlayer 140 is 0.01 μm or more, sufficient adhesion strength between the resin substrate 120 and the inorganic oxide layer 150 or oxygen barrier film 130 can be obtained, and the oxygen barrier properties will also be good. If the thickness of the underlayer 140 is 1 μm or less, it is easy to form a uniform coated surface, and drying load and manufacturing costs can be suppressed.

[0169] <Inorganic oxide layer> Examples of inorganic oxide layers 150 include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, tin oxide, zinc oxide, and indium oxide. Aluminum oxide or silicon oxide are particularly preferred because they offer excellent productivity and superior oxygen barrier and water vapor barrier properties in terms of heat resistance and humidity resistance. The inorganic oxide layer 150 may contain one of these materials alone or a combination of two or more. The thickness of the inorganic oxide layer 150 is preferably 1 to 200 nm. A thickness of 1 nm or more provides excellent oxygen barrier and water vapor barrier properties, while a thickness of 200 nm or less allows for lower manufacturing costs and reduces cracking due to external forces such as bending and pulling, thereby suppressing deterioration of barrier properties. The inorganic oxide layer 150 can be formed by known film deposition methods such as vacuum deposition, sputtering, ion plating, or plasma vapor deposition (CVD).

[0170] <Oxygen barrier coating> The oxygen barrier coating 130 may be a known oxygen barrier coating formed by a wet coating method. The oxygen barrier coating 130 is obtained by forming a coating film made of a coating agent on a substrate layer 140 or an inorganic oxide layer 150 by a wet coating method, and then drying this coating film. Note that the coating film is a wet film, and the coating film is a dry film.

[0171] As the oxygen barrier coating 130, a coating (organic-inorganic composite coating) containing at least one of a metal alkoxide and its hydrolysate, or its reaction product, and a water-soluble polymer is preferred. Furthermore, a coating containing at least one of a silane coupling agent and its hydrolysate is preferred.

[0172] Examples of metal alkoxides and their hydrolysates contained in organic-inorganic composite films include tetraethoxysilane [Si(OC2H5)4] and triisopropoxyaluminum [Al(OC3H7)3], which have the general formula M(OR). nExamples include substances represented by [the formula] and their hydrolysates. One of these may be included alone, or two or more may be included in combination.

[0173] In an organic-inorganic composite film, the total content of at least one of metal alkoxides and their hydrolysates, or their reaction products, is, for example, 40 to 70% by mass. From the viewpoint of further reducing oxygen permeability, the lower limit of the total content of at least one of metal alkoxides and their hydrolysates, or their reaction products, in an organic-inorganic composite film may be 50% by mass. From a similar viewpoint, the upper limit of the total content of at least one of metal alkoxides and their hydrolysates, or their reaction products, in an organic-inorganic composite film may be 65% by mass.

[0174] The water-soluble polymers included in the organic-inorganic composite membrane are not particularly limited, and examples include polyvinyl alcohol-based polymers, polysaccharides such as starch, methylcellulose, and carboxymethylcellulose, and acrylic polyol-based polymers. From the viewpoint of further improving oxygen gas barrier properties, it is preferable that the water-soluble polymers include polyvinyl alcohol-based polymers. The number-average molecular weight of the water-soluble polymers is, for example, 40,000 to 180,000.

[0175] Polyvinyl alcohol-based water-soluble polymers can be obtained, for example, by saponifying (including partial saponification) polyvinyl acetate. These water-soluble polymers may contain several tens of percent of acetate groups, or they may contain only a few percent of acetate groups.

[0176] The content of water-soluble polymers in the organic-inorganic composite membrane is, for example, 15 to 50% by mass. The lower limit of the content of water-soluble polymers in the organic-inorganic composite membrane may be 20% by mass from the viewpoint of further reducing oxygen permeability. The upper limit of the content of water-soluble polymers in the organic-inorganic composite membrane may be 45% by mass from the viewpoint of further reducing oxygen permeability.

[0177] Examples of silane coupling agents and their hydrolysates included in organic-inorganic composite films include silane coupling agents having organic functional groups. Examples of such silane coupling agents and their hydrolysates include ethyltrimethoxysilane, vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, glycidooxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and their hydrolysates. One of these may be included alone, or two or more may be included in combination. .

[0178] It is preferable that at least one of the silane coupling agent and its hydrolysate has an epoxy group as an organic functional group. Examples of silane coupling agents having an epoxy group include γ-glycidooxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The silane coupling agent having an epoxy group and its hydrolysate may also have an organic functional group other than the epoxy group, such as a vinyl group, an amino group, a methacrylic group, or a ureyl group.

[0179] Silane coupling agents having organic functional groups and their hydrolysates can further improve the oxygen barrier properties of the oxygen barrier film 130 and its adhesion to the underlayer 140 or inorganic oxide layer 150 through the interaction of their organic functional groups with the hydroxyl groups of water-soluble polymers. In particular, the interaction between the epoxy groups of the silane coupling agent and its hydrolysates and the hydroxyl groups of polyvinyl alcohol can form an oxygen barrier film 130 that exhibits particularly excellent oxygen barrier properties and adhesion to the underlayer 140 or inorganic oxide layer 150.

[0180] In an organic-inorganic composite membrane, the total content of at least one of the silane coupling agent and its hydrolysate, or its reaction product, is, for example, 1 to 15% by mass. From the viewpoint of further reducing oxygen permeability, the lower limit of the total content of at least one of the silane coupling agent and its hydrolysate, or its reaction product, in the organic-inorganic composite membrane may be 2% by mass. From a similar viewpoint, the upper limit of the total content of at least one of the silane coupling agent and its hydrolysate, or its reaction product, in the organic-inorganic composite membrane may be 12% by mass.

[0181] The organic-inorganic composite film may contain crystalline inorganic layered compounds having a layered structure. Examples of inorganic layered compounds include clay minerals such as kaolinite, smectite, or mica minerals. These may be used individually or in combination of two or more. The particle size of the inorganic layered compound is, for example, 0.1 to 10 μm. The aspect ratio of the inorganic layered compound is, for example, 50 to 5000.

[0182] As inorganic layered compounds, smectite clay minerals are preferred because they can form a film with excellent oxygen barrier properties and adhesion strength through intercalation of water-soluble polymers between the layers of the layered structure. Specific examples of smectite clay minerals include montmorillonite, hectorite, saponite, and water-swellable synthetic mica.

[0183] Another preferred example of the oxygen barrier film 130 is a film containing a polyvalent metal salt of carboxylic acid, which is a reaction product of the carboxyl group of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B) (polycarboxylic acid polyvalent metal salt film). In this case, the polycarboxylic acid polyvalent metal salt film may be formed by applying and heating a coating agent which is a mixture of the polycarboxylic acid polymer (A) and the polyvalent metal compound (B), or it may be a polycarboxylic acid polyvalent metal salt film formed by applying and drying a coating agent mainly composed of the polycarboxylic acid polymer (A) to form film A, then applying and drying a coating agent mainly composed of the polyvalent metal compound (B) to form film B, and then crosslinking the A / B layers.

[0184] [Polycarboxylic acid polymer (A)] Polycarboxylic acid polymers are polymers having two or more carboxyl groups in their molecule. Examples of polycarboxylic acid polymers include (co)polymers of ethylenically unsaturated carboxylic acids; copolymers of ethylenically unsaturated carboxylic acids with other ethylenically unsaturated monomers; and acidic polysaccharides having carboxyl groups in their molecule, such as alginic acid, carboxymethylcellulose, and pectin. Examples of ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of ethylenically unsaturated monomers copolymerizable with ethylenically unsaturated carboxylic acids include ethylene, propylene, vinyl acetate and other saturated vinyl carboxylic acid esters, alkyl acrylates, alkyl methacrylates, alkyl itaconates, vinyl chloride, vinylidene chloride, styrene, acrylamide, and acrylonitrile. These polycarboxylic acid polymers may be used individually or in combination of two or more types.

[0185] As for the components, among the above, from the viewpoint of the gas barrier properties of the resulting gas barrier film, a polymer containing structural units derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid, and crotonic acid is preferred, and a polymer containing structural units derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, and itaconic acid is particularly preferred. In the polymer, the proportion of structural units derived from at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, and itaconic acid is preferably 80 mol% or more, and more preferably 90 mol% or more (provided that the total of all structural units constituting the polymer is 100 mol%). The polymer may be a homopolymer or a copolymer. If the polymer is a copolymer containing structural units other than the above structural units, examples of such other structural units include structural units derived from ethylenically unsaturated monomers copolymerizable with the aforementioned ethylenically unsaturated carboxylic acids.

[0186] The number-average molecular weight of the polycarboxylic acid polymer is preferably in the range of 2,000 to 10,000,000, and more preferably in the range of 5,000 to 1,000,000. If the number-average molecular weight is less than 2,000, the resulting gas barrier film may not achieve sufficient water resistance, and moisture may cause deterioration of gas barrier properties and transparency, or whitening may occur. On the other hand, if the number-average molecular weight exceeds 10,000,000, the viscosity of the coating agent used to form the oxygen barrier film 130 increases, which may impair the coatability. The above number-average molecular weight is the polystyrene-converted number-average molecular weight determined by gel permeation chromatography (GPC).

[0187] When a coating agent mainly composed of a polycarboxylic acid polymer (A) is applied and dried to form film A, and then film B is formed, some of the carboxyl groups of the polycarboxylic acid polymer may be neutralized in advance with a basic compound. By neutralizing some of the carboxyl groups of the polycarboxylic acid polymer in advance, the water resistance and heat resistance of film A can be further improved. As the basic compound, at least one basic compound selected from the group consisting of polyvalent metal compounds, monovalent metal compounds, and ammonia is preferred. As the polyvalent metal compound, compounds exemplified in the description of polyvalent metal compound (B) described later can be used. Examples of monovalent metal compounds include sodium hydroxide and potassium hydroxide.

[0188] Various additives can be added to coating agents mainly composed of polycarboxylic acid polymers (A). These additives include crosslinking agents, curing agents, leveling agents, defoaming agents, antiblocking agents, antistatic agents, dispersants, surfactants, softeners, stabilizers, film-forming agents, and thickeners, as long as they do not impair the barrier performance.

[0189] A solvent is preferred for coating agents mainly composed of a polycarboxylic acid polymer (A). Examples of aqueous media include water, water-soluble or hydrophilic organic solvents, or mixtures thereof. Aqueous media are usually water or mainly composed of water. The water content in the aqueous media is preferably 70% by mass or more, and more preferably 80% by mass or more. Examples of water-soluble or hydrophilic organic solvents include alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; cellosolves; carbitols; and nitriles such as acetonitrile.

[0190] [Polyvalent metal compounds (B)] The polyvalent metal compound is not particularly limited as long as it is a compound that reacts with the carboxyl group of the polycarboxylic acid polymer to form a polyvalent metal salt of the polycarboxylic acid, and examples include zinc oxide particles, magnesium oxide particles, magnesium methoxide, copper oxide, and calcium carbonate. These may be used individually or in combination. Zinc oxide is preferred from the viewpoint of the oxygen barrier properties of the oxygen barrier film.

[0191] Zinc oxide is an inorganic material with ultraviolet absorption capabilities. While the average particle size of zinc oxide particles is not particularly limited, from the viewpoint of gas barrier properties, transparency, and coating suitability, an average particle size of 5 μm or less is preferred, more preferably 1 μm or less, and particularly preferred to be 0.1 μm or less.

[0192] When a coating agent mainly composed of a polyvalent metal compound (B) is applied and dried to form a B film, various additives may be included in addition to zinc oxide particles as needed, to the extent that they do not impair the effects of the present disclosure. These additives may include resins soluble or dispersible in the solvent used in the coating agent, dispersants soluble or dispersible in the solvent, surfactants, softeners, stabilizers, film-forming agents, thickeners, and the like.

[0193] Among the above, it is preferable to include a resin that is soluble or dispersible in the solvent used in the coating agent. This improves the coating properties and film-forming properties of the coating agent. Examples of such resins include alkyd resins, melamine resins, acrylic resins, urethane resins, polyester resins, phenolic resins, amino resins, fluororesins, epoxy resins, and isocyanate resins.

[0194] Furthermore, it is preferable to include a dispersant that is soluble in or dispersible in the solvent used in the coating agent. This improves the dispersibility of polyvalent metal compounds. Anionic surfactants or nonionic surfactants can be used as the dispersant. Examples of such surfactants include (poly)carboxylates, alkyl sulfates, alkylbenzene sulfons, alkylnaphthalene sulfons, alkyl sulfosuccinates, alkyl diphenyl ether disulfons, alkyl phosphates, aromatic phosphates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, alkyl allyl sulfates, polyoxyethylene alkyl phosphates, sorbitan alkyl esters, glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene sorbitan alkyl esters, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, polyoxyethylene sorbitol fatty acid esters, polyoxy fatty acid esters, and polyoxyethylene alkylamines. These surfactants may be used individually or in combination of two or more.

[0195] When a coating agent mainly composed of a polyvalent metal compound (B) contains an additive, the mass ratio of the polyvalent metal compound to the additive (polyvalent metal compound:additive) is preferably in the range of 30:70 to 99:1, and preferably in the range of 50:50 to 98:2.

[0196] Examples of solvents used in coating agents mainly composed of polyvalent metal compounds (B) include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, and butyl acetate. These solvents may be used individually or in combination of two or more. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of coating properties. Furthermore, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred from the viewpoint of manufacturability.

[0197] When forming a polyvalent metal salt film of polycarboxylic acid by applying and drying a coating agent which is a mixture of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B), the polycarboxylic acid polymer (A) and the polyvalent metal compound (B) can be mixed with water or alcohols as a solvent, along with a resin or dispersant that can dissolve or disperse in the solvent, and additives as needed, to form a coating agent which can then be applied and dried using a known coating method to form a polyvalent metal salt film of polycarboxylic acid. Examples of coating methods include the casting method, dipping method, roll coating method, gravure coating method, screen printing method, reverse coating method, spray coating method, kit coating method, die coating method, metering bar coating method, chamber doctor combined coating method, and curtain coating method.

[0198] The thickness of the oxygen barrier film 130 is set according to the required oxygen barrier performance, and may be, for example, 0.05 to 5 μm. A thickness of 0.05 to 1 μm is preferred for the oxygen barrier film 130, and 0.1 to 0.5 μm is more preferred. If the thickness of the oxygen barrier film 130 is 0.05 μm or more, sufficient oxygen barrier performance is easily obtained. If the thickness of the oxygen barrier film 130 is 1 μm or less, it is easy to form a uniform coated surface, and drying load and manufacturing costs can be reduced.

[0199] In the oxygen barrier coating 130, the gas barrier film having the organic-inorganic composite coating or the polyvalent metal salt coating of polycarboxylic acid exhibits excellent oxygen barrier properties even after boiling or retort sterilization. When laminated with a sealant film, it has sufficient adhesion and sealing strength as a packaging material for boiling and retort processing. Furthermore, it has advantages such as transparency not found in metal foils or metal vapor-deposited films, excellent flexibility and stretch resistance, and no risk of generating harmful substances such as dioxins.

[0200] [Method for manufacturing gas barrier film] The gas barrier film 101 can be manufactured by forming either a base layer 140 or an inorganic oxide layer 150, or both, on the first surface 21 of a resin substrate 120, and then forming an oxygen barrier film 130 on the base layer 140 or the inorganic oxide layer 150. The manufacturing method of the gas barrier film 101 of this disclosure includes, for example, a sorting step, a base layer formation step, an inorganic oxide layer formation step, and an oxygen barrier film formation step.

[0201] For example, the sorting process involves selecting materials with a surface diameter of 8 μm or larger, with 20 protrusions per millimeter. 2 The following is a step in selecting the resin substrate raw material as the resin substrate 120. The number of protrusions on the surface of the resin substrate raw material is measured in the same way as the method for measuring the number of protrusions on the first surface 21 of the resin substrate 120 described above. As the resin substrate 120, a commercially available product may be used, or one manufactured by a known method may be used.

[0202] The base layer formation process includes, for example, a step of forming a coating film by applying a coating agent to at least the first surface 21 of the resin substrate 120 using a wet coating method, and then forming the base layer 140 by drying the coating film (removing the solvent). Known wet coating methods can be used for applying the coating agent. Examples of wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. Known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used to dry the coating film. Examples of drying conditions include drying at 90°C for 10 seconds.

[0203] The inorganic oxide layer formation process includes, for example, a step of forming an inorganic oxide layer 150 on the first surface 21 of the resin substrate 120 or on the underlayer 140 by the vacuum deposition method, sputtering method, ion plating method, or plasma vapor deposition (CVD) method described above.

[0204] The oxygen barrier film formation process includes, for example, the step of applying a coating agent to a substrate layer 140 or an inorganic oxide layer 150 by a wet coating method to form a coating film, and then drying the coating film (removing the solvent) to form an oxygen barrier film 130. Known wet coating methods can be used for applying the coating agent. Examples of wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. Known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used to dry the coating film. Examples of drying conditions include 90°C for 10 seconds. The oxygen barrier film 130 may be formed by a single application and drying, or by repeating the application and drying process multiple times using the same or different coating agents.

[0205] If the manufacturing method of the gas barrier film 101 of this disclosure includes a sorting step, the surface has 20 protrusions / mm² with a diameter of 8 μm or more. 2 The following resin substrate 120 can be efficiently applied. Therefore, by having a sorting process, a gas barrier film with improved oxygen barrier properties can be efficiently manufactured. In addition, by having a sorting process, a gas barrier film 101 with good printability can be efficiently manufactured.

[0206] The gas barrier film 101 of this disclosure may further have, as necessary, a printing layer, a protective layer, a light-shielding layer, an adhesive layer, a heat-sealable heat-sealable layer, or other functional layers. If the gas barrier film 101 of this disclosure has a heat-sealable heat-sealable layer, this heat-sealable layer is disposed on at least one of the outermost layers of the gas barrier film 101. The presence of the heat-sealable layer of the gas barrier film 101 makes the gas barrier film 101 heat-sealable (e.g., a package or a lid). The heat-sealable layer can be laminated, for example, to a laminate obtained by forming the base layer 140, the inorganic oxide layer 150, and the oxygen barrier film 130 of this embodiment on one or both sides of a resin substrate 120, using a known adhesive such as a polyurethane-based, polyester-based, or polyether-based adhesive, by a known dry lamination method, extrusion lamination method, or the like.

[0207] <Effects and Effects> The gas barrier film 101 of this disclosure has a resin layer forming the first surface 21 made of a polyolefin copolymer resin, and the first surface has 20 protrusions / mm² with a Ferret diameter of 8 μm or more as measured by the measurement method. 2 On the first surface 21 of the resin substrate 120, either a base layer 140 or an inorganic oxide layer 150, or both the base layer 140 and the inorganic oxide layer 150, are laminated, and an oxygen barrier film 130 is further laminated. The gas barrier film 101 of this disclosure has a surface layer 23 made of a polyolefin copolymer resin, with 20 protrusions / mm² having a ferret diameter of 8 μm or more. 2Since the oxygen barrier film 130 is formed on the resin substrate 120 via either the underlayer 140 or the inorganic oxide layer 150, or both, film defects caused by large protrusions on the substrate surface are less likely to occur, resulting in better oxygen barrier properties and better adhesion of the oxygen barrier film 130. In addition, the gas barrier film 101 of this disclosure does not require the underlayer 140, inorganic oxide layer 150, and oxygen barrier film 130 to be unnecessarily thick, thus improving productivity and reducing material usage. Therefore, by using the gas barrier film 101 of this disclosure as a packaging material, it is possible to have sufficient lamination strength as a packaging material and to improve the quality retention of contents at a low cost. [Examples]

[0208] The embodiments of this disclosure will be described in more detail below with reference to examples and comparative examples. However, this disclosure is not limited to the following embodiments.

[0209] The materials used in each of the following examples are listed below. [Materials used] <Resin substrate> α1: Biaxially oriented polypropylene film (product name: M-1, thickness 20 μm, single-sided corona treated, manufactured by Mitsui Chemicals Tohcello Co., Ltd.). α2: Biaxially oriented polypropylene film (product name: ME-1, thickness 20 μm, single-sided corona treated, manufactured by Mitsui Chemicals Tohcello Co., Ltd.). α3: Biaxially oriented polypropylene film (product name: TS18TI-TPN, thickness 18μm, single-sided corona treated, manufactured by Max Speciality Films Limited). α4: Biaxially oriented polypropylene film (product name: P2111, thickness 20 μm, single-sided corona treated, manufactured by Toyobo Co., Ltd.). α5: Biaxially oriented polypropylene film (product name: P2171, thickness 20 μm, single-sided corona treated, manufactured by Toyobo Co., Ltd.). α6: Biaxially oriented polypropylene film (product name: P2102, thickness 20 μm, single-sided corona treated, manufactured by Toyobo Co., Ltd.). α7: Biaxially oriented polypropylene film (product name: P2161, thickness 20 μm, single-sided corona treated, manufactured by Toyobo Co., Ltd.). α8: Biaxially oriented polypropylene film (product name: VPH2011, thickness 20 μm, single-sided corona treated, average particle size of A and B agents on the corona-treated side is 2 μm, manufactured by AJPlast). α9: Biaxially oriented polypropylene film (product name: VPH2011, thickness 20 μm, single-sided corona treated, average particle size of AB agent on the corona-treated side is 4 μm, manufactured by AJPlast). α10: Biaxially oriented polypropylene film (product name: PB210J, thickness 20 μm, single-sided corona treated, manufactured by Futamura Chemical Co., Ltd.). α11: Polyethylene terephthalate film (product name: P60, thickness 12μm, single-sided corona treated, manufactured by Toray Industries, Inc.). α12: Polyethylene terephthalate film (product name: E5102, thickness 12 μm, single-sided corona treated, manufactured by Toyobo Co., Ltd.). α13: Polyethylene film (product name: HD, thickness 40μm, single-sided corona treated, manufactured by Tamapoly Co., Ltd.). α14: Polyethylene film (product name: HS31, thickness 30μm, single-sided corona treated, manufactured by Tamapoly Co., Ltd.). α15: Linear low-density polyethylene film (product name: UB-3, thickness 40 μm, single-sided corona treated, manufactured by Tamapoly Co., Ltd.). α16: Polyethylene film (product name: PE3K-H, thickness 25μm, single-sided corona treated, manufactured by Futamura Chemical Co., Ltd.). α17: Polyethylene film (product name: PE3M, thickness 25μm, single-sided corona treated, manufactured by Futamura Chemical Co., Ltd.). α18: Linear low-density polyethylene film (product name: LL-XHT, thickness 25 μm, single-sided corona treated, manufactured by Futamura Chemical Co., Ltd.). α19: Linear low-density polyethylene film (product name: LL-RP2, thickness 25 μm, single-sided corona treated, manufactured by Futamura Chemical Co., Ltd.). α20: Polyethylene film (25 μm thick, corona treated on one side, manufactured by WINPAK Limited).

[0210] <Manufacturing Example 1> Using Acrydic CL-1000 (manufactured by DIC Corporation) as the acrylic polyol and Coronate 2030 (manufactured by Tosoh Corporation), a TDI-type curing agent, as the isocyanate compound, the acrylic polyol and isocyanate compound were blended in a solids weight ratio of 6:4, and a mixed solution for forming the base layer (solids: 2% by mass) was prepared using a diluent (ethyl acetate).

[0211] <Manufacturing Example 2> A polyacrylic acid aqueous solution with a number average molecular weight of 200,000 (Aron A-10H, manufactured by Toagosei Co., Ltd., solid content concentration 25% by mass) was diluted with 58.9 parts by mass of distilled water. Then, 0.44 parts by mass of aminopropyltrimethoxysilane (APTMS, manufactured by Aldrich) was added, and the mixture was stirred to obtain a homogeneous solution, thereby preparing a coating agent mainly composed of a polycarboxylic acid polymer.

[0212] <Manufacturing Example 3> A coating agent mainly composed of a polyvalent metal compound was prepared by mixing 100 parts by mass of zinc oxide fine particle aqueous dispersion (ZE143, manufactured by Sumitomo Osaka Cement) and 2 parts by mass of the hardening agent Liofol HAERTER UR 5889-21 (manufactured by Henkel).

[0213] <Manufacturing Example 4> Aqueous solutions were prepared by dissolving polyvinyl alcohol resin (PVA, trade name: Poval PVA-105, manufactured by Kuraray Co., Ltd., saponification degree 98-99%, polymerization degree 500) and by hydrolyzing tetraethoxysilane (TEOS) and γ-glycidoxypropyltrimethoxysilane (GPTMS, trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) with 0.02 mol / L hydrochloric acid. These aqueous solutions were then blended so that the weight ratio of PVA:TEOS:GPTMS before hydrolysis was 40:50:10. Furthermore, a diluent was added to the blended aqueous solutions so that the solvent component was water:isopropyl alcohol in a mass ratio of 90:10, thereby preparing a coating agent (5% by mass) for forming an organic-inorganic composite film.

[0214] [Measurement of the black area ratio of resin substrates] The black area ratio was determined for the corona-treated surface of resin substrates α1-12 according to the image acquisition and image analysis conditions described above. The results are shown in Table 1. An Olympus OLS-4000 optical microscope with a 10x objective lens (MPFLN10) was used to measure the black area ratio, and Scion ImageJ from Scion Inc. was used as the image analysis software.

[0215] [Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-4] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate described in Table 1 using a gravure printing machine, forming a coating film, and drying it by passing it through a 100°C oven for 10 seconds. Next, a coating agent mainly composed of a polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed base layer using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of a polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polyvalent metal salt film of polycarboxylic acid, and obtaining the gas barrier films of Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-4.

[0216] <Printability Evaluation> For each example, black ink (product name: N920LPGT, manufactured by Toyo Ink Co., Ltd.) was used to print tonal values ​​of 5% to 50% (in 5% increments) on the oxygen barrier coating of the gas barrier film using a gravure printing press. The ink viscosity was 14 seconds (Zaan cup #3, 25°C). The printing speed was 150 m / min and the drying temperature was 50°C. After printing, the surface was observed with an optical microscope and the number of dot defects was counted. The judgment was as follows: fewer than 5 dot defects in a 6 mm square area was ○, 5 to 20 were △, and 21 or more were ×. The judgment results are shown in Table 1.

[0217] "Dot defects" refer to a condition where ink does not adhere well to the film substrate, resulting in some dots (halftone dots) not being transferred. The fewer dot defects there are, even at low halftone dot density levels, the better the printability of the highlight areas.

[0218] <Evaluation of oxygen barrier and water vapor barrier properties after retort processing> For each example of gas barrier film, a gas barrier laminate film for retort processing was fabricated by laminating it with CPP (polypropylene film) using an adhesive, resulting in a gas barrier film / adhesive / CPP configuration. The adhesive used was a two-component curing adhesive manufactured by Mitsui Chemicals Polyurethane, Takelac A620 (main component) / Takenate A65 (curing agent). The CPP used was a polypropylene film manufactured by Toray Film Processing, Trefan ZK93KM (60 μm). The films were dry-laminated using a HIRANO TECSEED Multi Coater TM-MC and cured at 40°C for 3 days. The oxygen barrier coating of the gas barrier film was positioned on the adhesive side.

[0219] A four-sided sealed A5-sized pouch was prepared using the obtained gas barrier laminated film, filled with 150 ml of tap water, and subjected to heat sterilization (retort treatment) in 120°C hot water for 30 minutes.

[0220] For gas barrier laminated films after retort processing, oxygen permeability was measured (cm³) using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) at 30°C and 70% RH. 3 / (m 2 The water vapor transmission rate (g / m³) was measured. Additionally, a water vapor transmission rate meter (product name: OERMATRAN-W-3 / 33, manufactured by MOCON) was used to measure the water vapor transmission rate (g / m³) under a 40°C, 90% RH atmosphere. 2 The measurement was taken on day 1. The measurement results are shown in Table 1.

[0221] [Table 1]

[0222] From the results shown in Table 1, the gas barrier films of Examples 1-1 to 1-8 had a black area ratio of 0.15% or less, and the oxygen permeability value under an atmosphere of 30°C and 70% relative humidity was 2 cm 3 / (m 2 ·day·atm) or less, and good oxygen barrier properties were obtained.

[0223] On the other hand, the gas barrier films of Comparative Examples 1-1 to 1-4 had a black area ratio of 0.15% or more, and the oxygen permeability value exceeded 2 cm 3 / (m 2 ·day·atm). Since the black area ratio exceeded 0.15% and was high, the oxygen permeability increased, and good oxygen barrier properties could not be obtained as compared with Examples 1-1 to 1-8.

[0224] From the results shown in Table 1, the gas barrier films of Examples 1-1 to 1-8 had a printing suitability of "○" at a dot density of 30% or more.

[0225] On the other hand, the gas barrier films of Comparative Examples 1-1 to 1-4 had a printing suitability of "×" at a dot density of 30%.

[0226] Thus, it was found that when the black area ratio was 0.15% or less, the printing suitability was good.

[0227] [Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4] On the corona-treated surface of the resin substrate described in Table 2, using a gravure printing machine, the mixed solution for forming the underlayer prepared in Production Example 1 was applied to form a coating film, which was passed through an oven at 100°C for 10 seconds and dried to form an underlayer with a thickness of 0.1 μm. Next, using a vacuum evaporation apparatus with an electron beam heating method, a mixed material containing two or more of metallic silicon, silicon monoxide, and silicon dioxide was evaporated to form an inorganic oxide layer composed of silicon oxide with a thickness of 30 nm on the underlayer. Subsequently, on the formed inorganic oxide layer, using a gravure printing machine, the coating agent for forming the organic-inorganic composite film prepared in Production Example 4 was applied to form a coating film, which was passed through an oven at 100°C for 10 seconds and dried to form an oxygen barrier film composed of an organic-inorganic composite film with a thickness of 0.3 μm, and the gas barrier films of Examples 2-1 to 2-6 and Comparative Examples 2-1 to 2-4 were obtained.

[0228] [Example 2-7] An oxygen barrier film of Example 2-7 was obtained in the same manner as in Example 2-3, except that an inorganic oxide layer was directly formed on the corona-treated surface of the resin substrate α8 without providing an underlayer.

[0229] <Printing suitability evaluation> Using a gravure printing machine, on the oxygen barrier film of the gas barrier film of each example, intaglio ink (product name: N920LPGT, manufactured by Toyo Ink Co., Ltd.) was printed in a tone with a dot density of 5% to 50% (in 5% increments). The ink viscosity was 14 seconds (Zahn cup #3, 25°C). The printing speed was 150 m / min and the drying temperature was 50°C. The surface after printing was observed with an optical microscope, and the locations of missing dots were counted. The judgment was ○ if there were less than 5 missing dots in a 6 mm square area, △ if there were 5 to 20 missing dots, and × if there were 21 or more missing dots. The judgment results are shown in Table 2.

[0230] Note that "missing dots" refers to a state where the ink does not adhere well to the film substrate and the dots (halftone dots) are not partially transferred. The fewer the locations of missing dots even in a state of low dot density, the better the printing suitability of the highlight part.

[0231] <Evaluation of oxygen barrier and water vapor barrier properties after retort processing> For each example of gas barrier film, a gas barrier laminate film for retort processing was fabricated by laminating it with CPP (polypropylene film) using an adhesive, resulting in a gas barrier film / adhesive / CPP configuration. The adhesive used was a two-component curing adhesive manufactured by Mitsui Chemicals Polyurethane, Takelac A620 (main component) / Takenate A65 (curing agent). The CPP used was a polypropylene film manufactured by Toray Film Processing, Trefan ZK93KM (60 μm). The films were dry-laminated using a HIRANO TECSEED Multi Coater TM-MC and cured at 40°C for 3 days. The oxygen barrier coating of the gas barrier film was positioned on the adhesive side.

[0232] A four-sided sealed A5-sized pouch was prepared using the obtained gas barrier laminated film, filled with 150 ml of tap water, and subjected to heat sterilization (retort treatment) in 120°C hot water for 30 minutes.

[0233] For gas barrier laminated films after retort processing, oxygen permeability was measured (cm³) using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) at 30°C and 70% RH. 3 / (m 2 The water vapor transmission rate (g / m³) was measured using a water vapor transmission rate analyzer (product name: PERMATRAN-W-3 / 33, manufactured by MOCON) at 40°C and 90% RH. 2 The measurement was taken on day 2. The measurement results are shown in Table 2.

[0234] [Table 2]

[0235] From the results shown in Table 2, the gas barrier films of Examples 2-1 to 2-7 had a black area ratio of 0.15% or less, and an oxygen permeability value of 3 cm in an atmosphere of 30°C and 70% relative humidity. 3 / (m 2Good oxygen barrier properties were obtained at (day·atm) or lower.

[0236] On the other hand, the gas barrier films of Comparative Examples 2-1 to 2-4 had a black area ratio of 0.15% or more and an oxygen permeability value of 5 cm². 3 / (m 2 At temperatures exceeding 0.15% (day·atm), the high black area ratio resulted in increased oxygen permeability, and a better oxygen barrier performance was not achieved compared to Examples 2-1 to 2-7.

[0237] As shown in Table 2, the gas barrier films of Examples 2-1 to 2-7 had printability of "○" at a halftone density of 30% or higher.

[0238] On the other hand, the gas barrier films of Comparative Examples 2-1 to 2-4 had printability of "×" at a halftone density of 30%.

[0239] Thus, it was found that printability is good when the black area ratio is 0.15% or less.

[0240] [Examples 3-1 to 3-7 and Comparative Example 3-1] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate described in Table 3 using a gravure printing machine, forming a coating film, and then drying it by passing it through a 100°C oven for 10 seconds. Next, an inorganic oxide layer of silicon oxide with a thickness of 30 nm was formed on the base layer by evaporating a mixed material containing two or more types of silicon, such as metallic silicon, silicon monoxide, and silicon dioxide, using an electron beam heating vacuum deposition apparatus. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polyvalent metal salt film of polycarboxylic acid, and obtaining the gas barrier films of Examples 3-1 to 3-7 and Comparative Example 3-1.

[0241] [Examples 3-8] A gas barrier film of Example 3-8 was obtained in the same manner as in Example 3-4, except that an inorganic oxide layer was directly formed on the corona-treated surface of the resin substrate α8 without providing a base layer.

[0242] <Printability Evaluation> For each example, black ink (product name: N920LPGT, manufactured by Toyo Ink Co., Ltd.) was used to print tonal values ​​of 5% to 50% (in 5% increments) on the oxygen barrier coating of the gas barrier film using a gravure printing press. The ink viscosity was 14 seconds (Zaan cup #3, 25°C). The printing speed was 150 m / min and the drying temperature was 50°C. After printing, the surface was observed with an optical microscope and the number of dot defects was counted. The judgment was as follows: fewer than 5 dot defects in a 6 mm square area was ○, 5 to 20 were △, and 21 or more were ×. The judgment results are shown in Table 3.

[0243] Note that "dot omission" refers to a state where the ink does not adhere well to the film substrate and dots (halftone dots) are partially not transferred. The fewer the dot omission areas up to the state of low dot density, the better the printing suitability of the highlight area.

[0244] <Oxygen barrier property and water vapor barrier property evaluation after retort treatment> For each gas barrier film, it was laminated with CPP (polypropylene film) using an adhesive to produce a gas barrier laminated film for retort treatment having a gas barrier film / adhesive / CPP structure. The adhesive used was a two-component curing type adhesive made by Mitsui Chemicals Polyurethane, Takelac A620 (main agent) / Takenate A65 (curing agent). The CPP used was a polypropylene film made by Toray Film Processing, Trephan ZK93KM (60 μm). It was dry laminated using a multi-coater TM-MC made by HIRANO TECSEED and cured at 40°C for 3 days. The gas barrier film was arranged so that the oxygen barrier film was on the adhesive side.

[0245] A 4-side sealed pouch of A5 size was made from the obtained gas barrier laminated film, filled with 150 ml of tap water as the contents, and subjected to heat sterilization treatment (retort treatment) in hot water at 120°C for 30 minutes.

[0246] For the gas barrier laminated film after retort treatment, using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON), the oxygen permeability (cm 3 / (m 2 ·day·atm)) was measured in an atmosphere of 30°C and 70% RH. Also, using a water vapor permeability measuring device (product name: PERMATRAN-W-3 / 33, manufactured by MOCON), the water vapor permeability (g / (m 2 ·day)) was measured in an atmosphere of 40°C and 90% RH. The measurement results are shown in Table 3.

[0247]

Table 3

[0248] From the results shown in Table 3, the gas barrier films of Examples 3-1 to 3-8 had a black area ratio of 0.15% or less, and an oxygen permeability value of 2 cm² in an atmosphere of 30°C and 70% relative humidity. 3 / (m 2 Good oxygen barrier properties were obtained at (day·atm) or lower.

[0249] On the other hand, the gas barrier film of Comparative Example 3-1 had a black area ratio of 0.15% or more, and an oxygen permeability value of 4.7 cm². 3 / (m 2 Examples 3-1 to 3-8 (day atm) In comparison, it did not provide the same level of oxygen barrier performance.

[0250] As shown in Table 3, the gas barrier films of Examples 3-1 to 3-8 had printability of "○" at a halftone density of 30% or higher.

[0251] On the other hand, the gas barrier film of Comparative Example 3-1 had a printability rating of "×" at a halftone density of 30%.

[0252] Thus, it was found that printability is good when the black area ratio is 0.15% or less.

[0253] [Examples 4-1 to 4-5 and Comparative Example 4-1] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate shown in Table 4 using a gravure printing machine, forming a coating film, and then drying it by passing it through a 100°C oven for 10 seconds. Next, metallic aluminum was evaporated using an electron beam heating vacuum deposition apparatus, and oxygen gas was introduced to form an inorganic oxide layer of aluminum oxide with a thickness of 20 nm on top of the base layer. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polyvalent metal salt film of polycarboxylic acid, and obtaining the gas barrier films of Examples 4-1 to 4-5 and Comparative Example 4-1.

[0254] [Examples 4-6] A gas barrier film of Example 4-6 was obtained in the same manner as in Example 4-2, except that an inorganic oxide layer was directly formed on the corona-treated surface of the resin substrate α8 without providing a base layer.

[0255] <Printability Evaluation> For each example, black ink (product name: N920LPGT, manufactured by Toyo Ink Co., Ltd.) was used to print tonal values ​​of 5% to 50% (in 5% increments) on the oxygen barrier coating of the gas barrier film using a gravure printing press. The ink viscosity was 14 seconds (Zaan cup #3, 25°C). The printing speed was 150 m / min and the drying temperature was 50°C. After printing, the surface was observed with an optical microscope and the number of dot defects was counted. The judgment was as follows: fewer than 5 dot defects in a 6 mm square area was ○, 5 to 20 were △, and 21 or more were ×. The judgment results are shown in Table 4.

[0256] "Dot defects" refer to a condition where ink does not adhere well to the film substrate, resulting in some dots (halftone dots) not being transferred. The fewer dot defects there are, even at low halftone dot density levels, the better the printability of the highlight areas.

[0257] <Evaluation of oxygen barrier and water vapor barrier properties after retort processing> For each example of gas barrier film, a gas barrier laminate film for retort processing was fabricated by laminating it with CPP (polypropylene film) using an adhesive, resulting in a gas barrier film / adhesive / CPP configuration. The adhesive used was a two-component curing adhesive manufactured by Mitsui Chemicals Polyurethane, Takelac A620 (main component) / Takenate A65 (curing agent). The CPP used was a polypropylene film manufactured by Toray Film Processing, Trefan ZK93KM (60 μm). The films were dry-laminated using a HIRANO TECSEED Multi Coater TM-MC and cured at 40°C for 3 days. The oxygen barrier coating of the gas barrier film was positioned on the adhesive side.

[0258] A four-sided sealed A5-sized pouch was prepared using the obtained gas barrier laminated film, filled with 150 ml of tap water, and subjected to heat sterilization (retort treatment) in 120°C hot water for 30 minutes.

[0259] For gas barrier laminated films after retort processing, oxygen permeability was measured (cm³) using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) at 30°C and 70% RH. 3 / (m 2 The water vapor transmission rate (g / m³) was measured using a water vapor transmission rate analyzer (product name: PERMATRAN-W-3 / 33, manufactured by MOCON) at 40°C and 90% RH. 2 The measurement was taken on day 2. The measurement results are shown in Table 4.

[0260] [Table 4]

[0261] From the results shown in Table 4, the gas barrier films of Examples 4-1 to 4-6 had a black area ratio of 0.15% or less, and an oxygen permeability value of 1 cm² in an atmosphere of 30°C and 70% relative humidity. 3 / (m 2 Good oxygen barrier properties were obtained at temperatures of 0.15% or less (day·atm). On the other hand, the gas barrier film of Comparative Example 4-1 had a black area ratio of 0.15% or more, and an oxygen permeability value of 1.5 cm². 3 / (m 2 In the case of (day·atm), good oxygen barrier properties were not obtained compared to Examples 4-1 to 4-6.

[0262] As shown in Table 4, the gas barrier films of Examples 4-1 to 4-6 had printability of "○" at a halftone density of 30% or higher.

[0263] On the other hand, the gas barrier film of Comparative Example 4-1 had a printability rating of "×" at a halftone density of 30%.

[0264] Thus, it was found that printability is good when the black area ratio is 0.15% or less.

[0265] [Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-3] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate described in Table 5 using a gravure printing machine, forming a coating film, and drying it by passing it through a 60°C oven for 10 seconds. Next, using an electron beam heating vacuum deposition apparatus, a mixed material containing two or more types of silicon, silicon monoxide, and silicon dioxide was evaporated to form an inorganic oxide layer of silicon oxide with a thickness of 30 nm on the base layer. Subsequently, a coating agent for forming an organic-inorganic composite film prepared in Production Example 4 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and drying it by passing it through a 60°C oven for 10 seconds to form an oxygen barrier film of organic-inorganic composite film with a thickness of 0.3 μm, obtaining the gas barrier films of Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-3.

[0266] [Examples 5-6] A gas barrier film of Example 5-6 was obtained in the same manner as in Example 5-2, except that an inorganic oxide layer was directly formed on the corona-treated surface of the resin substrate α14 without providing a base layer.

[0267] [Examples 5-7 to 5-11 and Comparative Examples 5-4 to 5-6] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate shown in Table 5 using a gravure printing machine, forming a coating film, and then passing it through a 60°C oven for 10 seconds to dry it. Next, metallic aluminum was evaporated using an electron beam heating vacuum deposition apparatus, and oxygen gas was introduced to form an inorganic oxide layer of aluminum oxide with a thickness of 20 nm on top of the base layer. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and then dried by passing it through a 60°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and then dried by passing it through a 50°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polyvalent metal salt film of polycarboxylic acid, and obtaining the gas barrier films of Examples 5-7 to 5-11 and Comparative Examples 5-4 to 5-6.

[0268] [Examples 5-12] A gas barrier film of Example 5-12 was obtained in the same manner as in Example 5-8, except that an inorganic oxide layer was directly formed on the corona-treated surface of the resin substrate α14 without providing a base layer.

[0269] [Examples 5-13] A gas barrier film of Example 5-13 was obtained in the same manner as in Example 5-8, except that a polyvalent metal compound film was formed on a base layer formed on the corona-treated surface of the resin substrate α14 without providing an inorganic oxide layer.

[0270] <Evaluation of oxygen barrier and water vapor barrier properties before and after boiling> For each example of gas barrier film, an adhesive was used to bond it with LLDPE (polyethylene film) to create a gas barrier laminated film for boiling treatment with a gas barrier film / adhesive / LLDPE configuration. The adhesive used was a two-component curing adhesive manufactured by Mitsui Chemicals Polyurethane, Takelac A620 (main component) / Takenate A65 (curing agent). The LLDPE used was TUX MC-S (60 μm) polyethylene film manufactured by Mitsui Chemicals Tohcello. Dry lamination was performed using a HIRANO TECSEED Multi Coater TM-MC, and cured at 40°C for 3 days. The gas barrier film was positioned so that the oxygen barrier coating was on the adhesive side.

[0271] A four-sided sealed A5-sized pouch was prepared using the obtained gas barrier laminated film, filled with 150 ml of tap water, and subjected to heat sterilization (boiling) in 90°C hot water for 30 minutes.

[0272] For gas barrier laminated films before and after boiling, oxygen permeability was measured using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) under an atmosphere of 30°C and 70% RH, and the oxygen permeability (cm³) was measured. 3 / (m 2 The water vapor transmission rate (g / m³) was measured using a water vapor transmission rate analyzer (product name: PERMATRAN-W-3 / 33, manufactured by MOCON) at 40°C and 90% RH. 2 The measurement was taken on day ()). The measurement results are shown in Table 5.

[0273] [Table 5]

[0274] From the results shown in Table 5, the gas barrier films of Examples 5-1 to 5-6 had a black area ratio of 0.15% or less, and the oxygen permeability value in an atmosphere of 30°C and 70% relative humidity was 2 cm before boiling. 3 / (m2 (day·atm) or less, after boiling, 3cm 3 / (m 2 The result was below (day·atm), indicating good oxygen barrier performance.

[0275] The gas barrier films of Examples 5-7 to 5-13 had a black area ratio of 0.15% or less, and the oxygen permeability value in an atmosphere of 30°C and 70% relative humidity remained constant at 1 cm before and after boiling. 3 / (m 2 The result was below (day·atm), indicating good oxygen barrier performance.

[0276] On the other hand, the gas barrier films of Comparative Examples 5-1 to 5-3 had a black area ratio of 0.15% or more, and an oxygen permeability value of 2 cm before boiling. 3 / (m 2 (day·atm) or more, after boiling, 3cm 3 / (m 2 The reading was above (day·atm), and good oxygen barrier performance could not be achieved.

[0277] The gas barrier films of Comparative Examples 5-4 to 5-6 had a black area ratio of 0.15% or more, and the oxygen permeability value changed by 1 cm before and after boiling. 3 / (m 2 The reading was above (day·atm), and good oxygen barrier performance could not be achieved.

[0278] [Examples 6-1 to 6-4 and Comparative Examples 6-1 to 6-5] In Examples 6-1 to 6-4 and Comparative Examples 6-1 to 6-5, the influence of the manufacturing lot of the resin substrate was investigated.

[0279] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate shown in Table 6A using a gravure printing machine, forming a coating film, and drying it by passing it through a 100°C oven for 10 seconds. Next, a coating agent mainly composed of a polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed base layer using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of a polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polycarboxylic acid polyvalent metal salt film, and obtaining the gas barrier films of Experimental Examples 6-1 to 6-4 and Comparative Examples 6-1 to 6-5.

[0280] [Examples 6-5 to 6-8 and Comparative Examples 6-6 to 6-10] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the corona-treated surface of the resin substrate shown in Table 6B using a gravure printing machine, forming a coating film, and drying it by passing it through a 100°C oven for 10 seconds. Next, using an electron beam heating vacuum deposition apparatus, a mixed material containing two or more types of silicon, silicon monoxide, and silicon dioxide was evaporated to form an inorganic oxide layer of silicon oxide with a thickness of 30 nm on the base layer. Subsequently, a coating agent for forming an organic-inorganic composite film prepared in Production Example 4 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form an oxygen barrier film of organic-inorganic composite film with a thickness of 0.3 μm, obtaining the gas barrier films of Examples 6-5 to 6-8 and Comparative Examples 6-6 to 6-10.

[0281] The black area ratio, oxygen permeability, and printability of the resin substrate were evaluated using the same method as in Examples 1-1 to 1-8. The measurement results are shown in Tables 6A and 6B.

[0282] [Table 6A]

[0283] [Table 6B] First, the resin substrates used in Examples 6-1 to 6-4 and Comparative Example 6-1 had the same material, part number, manufacturer, and thickness, but were from different manufacturing lots. Similarly, the resin substrates used in Examples 6-5 to 6-8 and Comparative Example 6-6 had the same material, part number, manufacturer, and thickness, but were from different manufacturing lots. However, the black area ratio of the resin substrates measured by the method described above differed from one manufacturing lot to another. In other words, from the measurement results of the black area ratio shown in Tables 6A and 6B, it was confirmed that the black area ratio measured by the method described above is not a value specific to the type of resin substrate (α8 or α9), but rather a value that varies depending on the manufacturing lot.

[0284] Next, from the results shown in Tables 6A and 6B, the gas barrier films of Examples 6-1 to 6-4 and Examples 6-5 to 6-8 (with a black area ratio of 0.15% or less of the resin substrate) showed good oxygen barrier properties in an atmosphere of 30°C and 70% relative humidity, and were evaluated as "○" for printability at a halftone density of 30% or higher. In contrast, the gas barrier film of Comparative Example 6-1 had a black area ratio of 0.15% of the resin substrate, and compared to Examples 6-1 to 6-4 with the same configuration, it had higher oxygen permeability and worsened printability. Similarly, the gas barrier film of Comparative Example 6-6 also had a black area ratio of 0.15% of the resin substrate, and compared to Examples 6-5 to 6-8 with the same configuration, it had higher oxygen permeability and worsened printability.

[0285] These results confirm that even when using the same type of resin substrate to construct a gas barrier film with the same configuration, differences in the performance of the gas barrier film can occur due to the manufacturing lot of the resin substrate. However, if the black area ratio of the resin substrate is 0.15% or less, the influence of the manufacturing lot of the resin substrate can be reduced.

[0286] Embodiment 2 of this disclosure will be described in more detail below with reference to examples and comparative examples. However, this disclosure is not limited to the following examples. The materials used in each of the following examples are shown below.

[0287] [Materials used] <Resin substrate> β1: Biaxially oriented polypropylene film (product name: ME-1, thickness 20 μm, surface layer is polyolefin copolymer resin, manufactured by Mitsui Chemicals Tohcello Co., Ltd.). β2: Biaxially oriented polypropylene film (product name: P2111, thickness 20 μm, surface layer is polyolefin copolymer resin, manufactured by Toyobo Co., Ltd.). β3: Biaxially oriented polypropylene film (product name: VPH2011, thickness 20 μm, surface layer is polyolefin copolymer resin, contains AB agent with an average particle size of 2 μm, manufactured by AJPlast). β4: Biaxially oriented polypropylene film (product name: VPH2011, thickness 20 μm, surface layer is polyolefin copolymer resin, contains AB agent with an average particle size of 4 μm, manufactured by AJPlast). β5: Biaxially oriented polypropylene film (product name: TS19TIMCP, thickness 19 μm, surface layer is polyolefin copolymer resin, manufactured by Max Speciality Films Limited). β6: Biaxially oriented polypropylene film (product name: TS18TIV, thickness 18 μm, surface layer is polyolefin copolymer resin, manufactured by Max Speciality Films Limited). β7: Biaxially oriented polypropylene film (product name: TS18TI-TPN, thickness 18 μm, surface layer is polypropylene homopolymer, manufactured by Max Speciality Films Limited). β8: Biaxially oriented polypropylene film (product name: M-1, thickness 20 μm, surface layer is polypropylene homopolymer, manufactured by Mitsui Chemicals Tohcello Co., Ltd.).

[0288] [Measurement of the number of protrusions on the surface of the resin substrate] For the surface (first surface) of the resin substrates β1 to β8 that form the oxygen barrier film, the number of protrusions with a Ferret diameter of 8 μm or more was determined according to the measurement conditions described above. The results are shown in Tables 7 to 10.

[0289] [Examples 7-1 to 7-3 and Comparative Examples 7-1 to 7-5] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Production Example 1 to the first surface of the resin substrate shown in Table 7 using a gravure printing machine, forming a coating film, and drying it by passing it through a 100°C oven for 10 seconds. Next, using an electron beam heating vacuum deposition apparatus, a mixed material containing two or more types of silicon, silicon monoxide, and silicon dioxide was evaporated to form an inorganic oxide layer of silicon oxide with a thickness of 30 nm on the base layer. Subsequently, a coating agent for forming an organic-inorganic composite film prepared in Production Example 4 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form an oxygen barrier film of organic-inorganic composite film with a thickness of 0.3 μm, obtaining the gas barrier films of Examples 7-1 to 7-3 and Comparative Examples 7-1 to 7-5.

[0290] [Example 7-4] A gas barrier film of Example 7-4 was obtained in the same manner as in Example 7-3, except that an inorganic oxide layer was directly formed on the first surface of the resin substrate β3 without providing a base layer.

[0291] <Evaluation of oxygen barrier properties, water vapor barrier properties, and laminate strength after retort processing> For each example of gas barrier film, a gas barrier laminate film for retort processing was prepared by laminating it with CPP (polypropylene film) using an adhesive, resulting in a gas barrier film / adhesive / CPP configuration. Mitsui Chemicals Polyurethane's two-component curing adhesive, Takelac A620 (main component) / Takenate A65 (curing agent), was used as the adhesive, and Toray Film Processing's polypropylene film, Trefan ZK93KM (60μm), was used as the CPP. Dry lamination was performed using a HIRANO TECSEED Multi-Coater TM-MC, and cured at 40°C for 3 days. The gas barrier film was positioned so that the oxygen barrier coating faced the adhesive side. A5-sized, four-sided sealed pouch was prepared from the obtained gas barrier laminate film, filled with 200ml of tap water, and subjected to heat sterilization (retort processing) in 120°C hot water for 30 minutes. For gas barrier laminated films after retort processing, oxygen permeability was measured (cm³) using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) at 30°C and 70% RH. 3 / (m 2 The water vapor transmission rate (g / m³) was measured using a water vapor transmission rate analyzer (product name: PERMATRAN-W-3 / 33, manufactured by MOCON) at 40°C and 90% RH. 2 The following measurements were taken: The results are shown in Table 7. For the gas barrier laminated film after retort treatment, test pieces were cut into 15 mm wide strips, and the lamination strength between the gas barrier film and the CPP film was measured using a universal testing machine Tensilon RTC-1250, peeling at a peeling speed of 300 m / min in a T-shape and at 180°. The results are shown in Table 7.

[0292] [Table 7]

[0293] The results shown in Table 7 indicate that the first surface of the resin substrate is a polyolefin copolymer resin, and that the first surface of the resin substrate has 20 protrusions / mm² with a ferret diameter of 8 μm or more. 2The gas barrier films of Examples 7-1 to 7-4 below have an oxygen permeability of 3 cm² under an atmosphere of 30°C and 70% RH. 3 / (m 2 It exhibits good oxygen barrier properties of less than 1 g / (m³) and the water vapor transmission value at 40°C and 90% RH is 1 g / (m³). 2 It showed good water vapor barrier properties of less than 20 per mm² on the first surface of the resin substrate, with a ferret diameter of 8 μm or more. 2 The gas barrier films of Comparative Examples 7-1 to 7-3, which exceed the limit, have an oxygen permeability value of 3 cm². 3 / (m 2 The value of water vapor transmission is greater than 1 g / (m³) and the water vapor transmission value is 1 g / (m³). 2 It exceeded (day) and had poor oxygen barrier and water vapor barrier properties.

[0294] As shown in Table 7, Comparative Examples 7-4 to 7-5, where the first surface of the resin substrate was a polypropylene homopolymer, showed insufficient strength after retort treatment, with a laminate strength of less than 2 N / 15 mm. In contrast, Examples 7-1 to 7-4, where the first surface of the resin substrate was a polyolefin copolymer resin, exhibited sufficient laminate strength of 2 N / 15 mm or more even after retort treatment. Example 7-4, in particular, showed good laminate strength even without an underlayer. Furthermore, "Substrate breakage" in Table 7 indicates that the resin substrate broke with a strength of 2 N / 15 mm or more without delamination between the gas barrier film and the CPP film, demonstrating sufficiently high laminate strength.

[0295] [Examples 8-1 to 8-3 and Comparative Examples 8-1 to 8-3] A base layer with a thickness of 0.1 μm was formed on the first surface of the resin substrate shown in Table 8 by applying the base layer formation mixture prepared in Manufacturing Example 1 using a gravure printing machine, and then drying it by passing it through a 100°C oven for 10 seconds. Next, an inorganic oxide layer of silicon oxide with a thickness of 30 nm was formed on the base layer by evaporating a mixed material containing two or more types of silicon, such as metallic silicon, silicon monoxide, and silicon dioxide, using an electron beam heating vacuum deposition apparatus. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polyvalent metal salt film of polycarboxylic acid, and obtaining the gas barrier films of Examples 8-1 to 8-3 and Comparative Examples 8-1 to 8-3.

[0296] [Example 8-4] A gas barrier film of Example 8-4 was obtained in the same manner as in Example 8-3, except that an inorganic oxide layer was directly formed on the first surface of the resin substrate β3 without providing a base layer.

[0297] <Evaluation of oxygen barrier properties, water vapor barrier properties, and laminate strength after retort processing> For each example of gas barrier film, a gas barrier laminate film for retort processing was prepared by laminating it with CPP (polypropylene film) using an adhesive, resulting in a gas barrier film / adhesive / CPP configuration. The adhesive used was a two-component curing adhesive manufactured by Mitsui Chemicals Polyurethane, Takelac A620 (main component) / Takenate A65 (curing agent). The CPP used was a polypropylene film manufactured by Toray Film Processing, Trefan ZK93KM (60 μm). Dry lamination was performed using a HIRANO TECSEED Multi Coater TM-MC, and cured at 40°C for 3 days. The oxygen barrier coating of the gas barrier film was positioned on the adhesive side. An A5-sized four-sided sealed pouch was prepared from the obtained gas barrier laminate film, filled with 200 ml of tap water, and subjected to heat sterilization treatment (retort processing) in 120°C hot water for 30 minutes. For gas barrier laminated films after retort processing, oxygen permeability was measured (cm³) using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) at 30°C and 70% RH. 3 / (m 2 The water vapor transmission rate (g / m³) was measured using a water vapor transmission rate analyzer (product name: PERMATRAN-W-3 / 33, manufactured by MOCON) at 40°C and 90% RH. 2 The following measurements were taken: The results are shown in Table 8. For the gas barrier laminated film after retort treatment, test pieces were cut into 15 mm wide strips, and the lamination strength between the gas barrier film and the CPP film was measured using a universal testing machine Tensilon RTC-1250, peeling at a peeling speed of 300 m / min in a T-shape and at 180°. The results are shown in Table 8.

[0298] [Table 8]

[0299] The results shown in Table 8 indicate that the first surface of the resin substrate is a polyolefin copolymer resin, and that the first surface of the resin substrate has 20 protrusions / mm² with a ferret diameter of 8 μm or more. 2 Below In some examples 8-1 to 8-4, the gas barrier film showed an oxygen permeability value of 2 cm² under an atmosphere of 30°C and 70% RH. 3 / (m 2 It exhibited good oxygen barrier properties below (day·atm). On the other hand, the first surface of the resin substrate had 20 protrusions / mm² with a ferret diameter of 8 μm or more. 2 Comparative Examples 8-1 to 8-3, in which the first surface of the super or resin substrate is a polypropylene homopolymer, have an oxygen permeability value of 2 cm². 3 / (m 2 At temperatures exceeding 1 / 20 (day / atm), oxygen barrier properties were poor.

[0300] As shown in Table 8, Comparative Examples 8-2 to 8-3, in which the first surface of the resin substrate was a polypropylene homopolymer, showed insufficient lamination strength after retort treatment, with a laminate strength of less than 2 N / 15 mm. In contrast, Examples 8-1 to 8-4, in which the first surface of the resin substrate was a polyolefin copolymer resin, exhibited sufficient lamination strength of 2 N / 15 mm or more even after retort treatment. In particular, Example 8-4 showed good lamination strength even without a base layer.

[0301] [Examples 9-1 to 9-3 and Comparative Examples 9-1 to 9-3] A base layer with a thickness of 0.1 μm was formed by applying the base layer forming mixture prepared in Production Example 1 to the first surface of the resin substrate described in Table 9 using a gravure printing machine, forming a coating film, and drying it by passing it through a 100°C oven for 10 seconds. Next, a coating agent mainly composed of a polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed base layer using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of a polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and drying it by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polyvalent metal salt film of polycarboxylic acid, and obtaining the gas barrier films of Examples 9-1 to 9-3 and Comparative Examples 9-1 to 9-3.

[0302] <Evaluation of oxygen barrier properties, water vapor barrier properties, and laminate strength after retort processing> For each example of gas barrier film, a gas barrier laminate film for retort processing was prepared by laminating it with CPP (polypropylene film) using an adhesive, resulting in a gas barrier film / adhesive / CPP configuration. Mitsui Chemicals Polyurethane's two-component curing adhesive, Takelac A620 (main component) / Takenate A65 (curing agent), was used as the adhesive, and Toray Film Processing's polypropylene film, Trefan ZK93KM (60μm), was used as the CPP. Dry lamination was performed using a HIRANO TECSEED Multi-Coater TM-MC, and cured at 40°C for 3 days. The gas barrier film was positioned so that the oxygen barrier coating faced the adhesive side. A5-sized, four-sided sealed pouch was prepared from the obtained gas barrier laminate film, filled with 200ml of tap water, and subjected to heat sterilization (retort processing) in 120°C hot water for 30 minutes. For gas barrier laminated films after retort processing, oxygen permeability was measured (cm³) using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON) at 30°C and 70% RH. 3 / (m 2The measurement of ·day·atm) was carried out. Also, using a water vapor permeability measuring device (product name: PERMATRAN-W-3 / 33, manufactured by MOCON), the water vapor permeability (g / (m 2 ·day)) was measured. The measurement results are shown in Table 9. Regarding the gas barrier laminated film after retort treatment, test pieces were cut out in strips with a width of 15 mm, and the laminate strength between the gas barrier film and the CPP film was measured by peeling at a peeling speed of 300 m / min in a T-shape and at 180° using a universal testing machine Tensilon RTC-1250. The measurement results are shown in Table 9.

[0303] [Table 9]

[0304] From the results shown in Table 9, the first surface of the resin substrate is a polyolefin-based copolymer resin, and the number of protrusions with a Feret diameter of 8 μm or more on the first surface of the resin substrate is 20 per mm 2 The gas barrier films of Examples 9-1 to 9-3, in which the number is less than or equal to the following, have an oxygen permeability value of 2 cm 3 / (m 2 ·day·atm) or less in an atmosphere of 30°C and 70% RH, showing good oxygen barrier properties, and also have a sufficient laminate strength of 2 N / 15 mm or more for the laminate strength after retort treatment. On the other hand, the gas barrier films of Comparative Examples 9-1 to 9-3, in which the number of protrusions with a Feret diameter of 8 μm or more on the first surface of the resin substrate exceeds 20 per mm 2 have an oxygen permeability value exceeding 2 cm 3 / (m 2 ·day·atm), showing poor oxygen barrier properties.

[0305] [Examples 10-1 and Comparative Example 10-1] A base layer with a thickness of 0.1 μm was formed by applying the base layer formation mixture prepared in Manufacturing Example 1 to the first surface of the resin substrate shown in Table 10 using a gravure printing machine, forming a coating film, and then passing it through a 100°C oven for 10 seconds to dry it. Next, metallic aluminum was evaporated using an electron beam heating vacuum deposition apparatus, and oxygen gas was introduced to form an inorganic oxide layer of aluminum oxide with a thickness of 20 nm on top of the base layer. Next, a coating agent mainly composed of the polycarboxylic acid polymer prepared in Production Example 2 was applied to the formed inorganic oxide layer using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polycarboxylic acid polymer film with a thickness of 0.2 μm. Furthermore, a coating agent mainly composed of the polyvalent metal compound prepared in Production Example 3 was applied to the polycarboxylic acid polymer film using a gravure printing machine to form a coating film, and then dried by passing it through a 100°C oven for 10 seconds to form a polyvalent metal compound film with a thickness of 0.2 μm, thereby forming an oxygen barrier film consisting of a polycarboxylic acid polyvalent metal salt film, and obtaining the gas barrier films of Example 10-1 and Comparative Example 10-1.

[0306] <Evaluation of oxygen barrier properties, water vapor barrier properties, and laminate strength after retort processing> For each gas barrier film, it was laminated to a CPP (polypropylene film) using an adhesive to produce a gas barrier laminated film for retort processing having a gas barrier film / adhesive / CPP structure. As the adhesive, a two-component curable adhesive manufactured by Mitsui Chemicals Polyurethane, Tacklac A620 (main component) / Takenate A65 (hardener) was used. As the CPP, a polypropylene film manufactured by Toray Film Processing, Trephan ZK93KM (60 μm) was used, and it was dry laminated using a multi-coater TM-MC manufactured by HIRANO TECSEED and cured at 40°C for 3 days. The oxygen barrier film of the gas barrier film was arranged so that it was on the adhesive side. A 4-side seal pouch of size A5 was produced from the obtained gas barrier laminated film, filled with 200 ml of tap water as the content, and subjected to heat sterilization treatment (retort treatment) in hot water at 120°C for 30 minutes. For the gas barrier laminated film after the retort treatment, using an oxygen permeability measuring device (product name: OXTRAN-2 / 20, manufactured by MOCON), the oxygen permeability (cm 3 / (m 2 ·day·atm)) was measured in an atmosphere of 30°C and 70% RH. Also, using a water vapor permeability measuring device (product name: PERMATRAN-W-3 / 33, manufactured by MOCON), the water vapor permeability (g / (m 2 ·day)) was measured in an atmosphere of 40°C and 90% RH. The measurement results are shown in Table 10. For the gas barrier laminated film after the retort treatment, test pieces were cut out in a strip shape with a width of 15 mm, and the lamination strength between the gas barrier film and the CPP film was measured by peeling at a peeling speed of 300 m / min in a T-shape and at 180° using a universal testing machine Tensilon RTC-1250. The measurement results are shown in Table 10.

[0307]

Table 10

[0308] From the results shown in Table 10, the first surface of the resin substrate is a polyolefin-based copolymer resin, and there are 20 protrusions with a Feret diameter of 8 μm or more on the first surface of the resin substrate per mm 2The gas barrier film of Example 10-1, as described below, has an oxygen permeability of 2 cm² under an atmosphere of 30°C and 70% RH. 3 / (m 2 The film exhibited good oxygen barrier properties (below 2N / 15mm) and had sufficient laminate strength after retort treatment (2N / 15mm or higher). On the other hand, the gas barrier film of Comparative Example 10-1, in which the first surface of the resin substrate was a polypropylene homopolymer, did not have sufficient strength, with a laminate strength (T-type peel) of less than 2N / 15mm after retort treatment. [Industrial applicability]

[0309] The gas barrier film disclosed herein exhibits excellent and stable gas barrier properties, even after retort processing. Furthermore, the surface condition of the base film can be easily assessed, and the quality can be stabilized even when the oxygen barrier coating is made thin, thereby reducing raw material costs.

[0310] In addition, the gas barrier film of this disclosure has good printability. Therefore, printing can be easily and beautifully applied to the surface of the gas barrier film.

[0311] The gas barrier film of this disclosure can be suitably used, for example, as a packaging material, and can also be suitably used as a packaging material for boiling and retorting processes. By using the gas barrier film of this disclosure as a packaging material, the quality preservation of the contents can be improved.

[0312] The gas barrier film disclosed herein can be used for applications other than packaging materials. Examples of applications other than packaging materials include films for electronic devices, films for solar cells, various functional films for fuel cells, and substrate films. [Explanation of Symbols]

[0313] 1. Gas barrier film 10 Resin substrate 20 Oxygen barrier coating 30 Lower strata 40 Inorganic acid layer

Claims

1. Resin substrate and The resin substrate comprises an oxygen barrier coating formed on one side, which is the first surface side, Between the resin substrate and the oxygen barrier coating, there is at least one of an underlayer and an inorganic oxide layer. The resin substrate has two or more resin layers, Of the two or more resin layers, the resin layer forming the first surface is made of a polyolefin copolymer resin, and the first surface has 20 protrusions / mm² with a ferret diameter of 8 μm or more, as measured by the following measurement method. ２ The following is a gas barrier film. <Measurement method> A white LED line light source is used to illuminate an arbitrary 36.6 mm square area on the first surface of a resin substrate at a light source distance of 100 mm and an incident angle of 83°. The transmitted light at a measurement angle of 90° is captured by a monochrome line camera to obtain an image. An analysis image of 3551 pixels × 5684 pixels (2.5 × 4.0 mm) is extracted from the captured image, and protrusions with a ferret diameter of 8 μm or more in the analysis image are counted.

2. The gas barrier film according to claim 1, wherein the resin substrate is a polyolefin resin.

3. The gas barrier film according to claim 1, wherein the resin substrate contains an antiblocking agent.

4. The gas barrier film according to any one of claims 1 to 3, wherein the thickness of the aforementioned underlayer is 0.01 to 1 μm.

5. The aforementioned underlayer contains organic polymers as its main component, The gas barrier film according to any one of claims 1 to 4, wherein the organic polymer comprises at least one of a polyacrylic resin, a polyol resin, a polyurethane resin, and a polyamide resin.

6. The gas barrier film according to any one of claims 1 to 5, wherein the thickness of the inorganic oxide layer is 1 to 200 nm.

7. The gas barrier film according to any one of claims 1 to 6, wherein the inorganic oxide layer is aluminum oxide or silicon oxide.

8. The gas barrier film according to any one of claims 1 to 7, wherein the thickness of the oxygen barrier coating is 0.05 to 1 μm.

9. The gas barrier film according to any one of claims 1 to 8, wherein the oxygen barrier film is a film comprising a metal alkoxide, a hydrolysis product of a metal alkoxide, and at least one of the reaction products of a metal alkoxide or a hydrolysis product of a metal alkoxide, and a water-soluble polymer.

10. The gas barrier film according to claim 9, wherein the oxygen barrier film comprises a silane coupling agent, a hydrolysis product of a silane coupling agent, and at least one of the reaction products of a silane coupling agent or a hydrolysis product of a silane coupling agent.

11. The gas barrier film according to any one of claims 1 to 8, wherein the oxygen barrier film contains a polyvalent metal salt of a carboxylic acid which is a reaction product of a carboxyl group of a polycarboxylic acid polymer (A) and a polyvalent metal compound (B).

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