JP2022185386A - Packaging materials and packaging bags - Google Patents

Abstract

To form a packaging material with a gas barrier film excellent in productivity and more excellent in oxygen barrier property.SOLUTION: A packaging material with a gas barrier film comprises a barrier base material, a barrier film on a first surface of the barrier base material, and at least one of an underlying layer and an inorganic oxide layer between the barrier base material and the barrier film, wherein among 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 projections/mm2 or less having a Feret diameter of 8 μm or more.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a packaging material and a packaging bag having gas barrier properties.

Packaging materials used for packaging food, pharmaceuticals, etc. are designed to prevent the ingress of gases (water vapor, oxygen, etc.) that denature the contents in order to prevent deterioration and putrefaction of the contents and maintain their functions and quality. It is required to have the property of preventing Therefore, film materials having gas barrier properties (gas barrier films) are used for these packaging materials.

As a gas barrier film, a film in which a gas barrier layer made of a material having gas barrier properties is provided on the surface of a resin substrate is known. As the gas barrier layer, a metal foil, a metal deposition film, and a film formed by a wet coating method are known. As a film, a resin film formed from a coating agent containing a resin such as a water-soluble polymer or polyvinylidene chloride, or a coating agent containing a water-soluble polymer and an inorganic layered mineral, which exhibits oxygen barrier properties. is known (Patent Document 1).

Furthermore, as a gas barrier layer, a vapor deposition thin film layer made of an inorganic oxide and a gas barrier composite coating containing an aqueous polymer, an inorganic layered compound, and a metal alkoxide are successively laminated (Patent Document 2), and a polycarboxylic acid-based polymer is used. A gas barrier layer containing a polyvalent metal salt of a carboxylic acid that is a reaction product of a combined carboxyl group and a polyvalent metal compound has been proposed (Patent Document 3).

In order to improve gas barrier properties, for example, Patent Document 4 discloses a gas barrier film in which a coating is formed on at least one surface of a base material and the surface roughness parameter RT/RA of the surface of the coating is 20 or less. Proposed. Here, RT is the distance between the maximum peak and the deepest valley of the surface roughness curve. RA is the centerline average roughness. According to the gas barrier film of Patent Document 4, an improvement in gas barrier properties is achieved.

Japanese Patent No. 6176239 JP-A-2000-254994 Japanese Patent No. 4373797 JP-A-9-150484

Oxygen barrier properties of gas barrier films obtained by forming a film on the surface of a resin base material by wet coating, vapor deposition, sputtering, or the like may be unstable depending on production lots.
Specifically, the oxygen barrier property of the gas barrier film was sometimes inferior to the original oxygen barrier property, that is, the oxygen barrier property expected from the material constituting the film and the thickness of the film.
In particular, when the thickness of the film is thin, such a problem tends to occur easily. Therefore, the thickness of the gas barrier layer has to be made thicker than necessary, which causes problems of poor productivity and excessive material costs.

In addition, polyolefin resin film as a resin base material is inexpensive and has high water vapor barrier properties, so it is often used as a packaging material. There was a drawback that the lamination strength was inferior when used as a gas barrier packaging material.

The present invention has been made in view of the above circumstances, and relates to a packaging material with gas barrier properties. It is an object of the present invention to provide a packaging material having a gas barrier film that exhibits excellent gas barrier properties as a packaging material and has sufficient adhesion strength as a packaging material.

In order to solve the above problems, the present invention provides a packaging material comprising at least a substrate, a gas barrier film layer and a sealant layer, wherein the barrier film layer is a barrier substrate and one surface of the barrier substrate. a barrier film formed on the first surface side, and having at least one of an underlying layer and an inorganic oxide layer between the barrier base material and the barrier film; or more resin layers, wherein, 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 is a ferret measured by the following measurement method. The packaging material has 20 projections/mm ² or less with a diameter of 8 μm or more.
<Measurement method>
An arbitrary area of 36.6 mm square on the first surface of the resin substrate is irradiated with light using a white LED line light source at a light source distance of 100 mm and an incident angle of 83 °, and transmitted light at a measurement angle of 90 ° is measured with a monochrome line camera. A photographed image is obtained by photographing, an analysis image of 3551 pixels×5684 pixels (2.5×4.0 mm) is cut out from the photographed image, and projections having a Feret diameter of 8 μm or more in the analysis image are counted.

Further, the barrier base material is characterized by being a polyolefin resin.

Further, it is characterized in that the underlayer has a thickness of 0.01 to 1 μm.

Further, the underlayer contains an organic polymer as a main component, and the organic polymer is a polyacrylic resin, a polyol resin, a polyurethane resin, a polyamide resin, or a reaction product of these organic polymers. It is characterized by including at least one.

Further, the inorganic oxide layer has a thickness of 1 to 200 nm.

Further, the inorganic oxide layer is characterized by being aluminum oxide or silicon oxide.

Further, the thickness of the barrier film is 0.05 to 1 μm.

Further, the barrier film is a film containing at least one of a metal alkoxide, a metal alkoxide hydrolyzate, and a metal alkoxide reaction product, and a water-soluble polymer.

Further, the barrier film contains at least one of a silane coupling agent, a hydrolyzate of the silane coupling agent, and a reaction product of the silane coupling agent.

Further, the barrier film is characterized in that it contains a polyvalent metal salt of carboxylic acid, which is a reaction product of the carboxy group of the polycarboxylic acid polymer (A) and the polyvalent metal compound (B). do.

Further, the substrate is characterized by being biaxially oriented polypropylene.

Further, the MD heat shrinkage of the substrate made of the biaxially oriented polypropylene is 20% or less when heat-treated at 150°C.

Further, the sealant layer is characterized by being unstretched polypropylene.

Also, a packaging bag obtained by arranging the sealant layers of the packaging material described above so as to face each other and heat-sealing at least a part of the periphery thereof.

According to the packaging material having gas barrier properties of the present invention, even if the thickness of the oxygen barrier coating of the gas barrier film is thin, there is little variation in performance between production lots, and the original oxygen barrier properties are stably exhibited. By doing so, it is possible to obtain a packaging material that can exhibit excellent gas barrier properties, has good adhesion of the oxygen barrier film, and has sufficient lamination strength.

1 is a cross-sectional view of a packaging material of one embodiment of the present invention; FIG. 1 is a cross-sectional view of a packaging material of one embodiment of the present invention; FIG. It is the schematic explaining the measuring device which measures the number of protrusions of the 1st surface of a barrier base material. It is the schematic explaining the principle which detects a protrusion part.

1 and 2 are sectional views showing one embodiment of the gas barrier packaging material 10 of the present invention.
FIG. 1 shows a packaging material having a construction in which a gas barrier film 2 is provided on one side of a base material 1 and a sealant layer 7 is laminated thereon. The substrate 1, the gas barrier film 2, and the sealant layer are bonded together via an adhesive layer 8, respectively. The gas barrier film 2 comprises a barrier base material 3, an underlayer 4, an inorganic oxide layer 5, and a barrier coating 6. In the example of FIG. It has a configuration in which the material 3 is positioned.
FIG. 2 shows a packaging material having a configuration in which a gas barrier film layer 2 is provided on one side of a substrate 1 and a sealant layer 7 is further laminated. , the barrier film 6 is positioned on the sealant layer 7 side.
In addition, in the case of a material that can be bonded without the adhesive layer 8, the adhesive layer 8 may be omitted. Further, although not shown, a print layer may be provided.

[Base material]
The substrate 1 is a layer that serves as a support.
As the resin constituting the base material 1, polyolefin is preferable, and examples of the polyolefin include polyethylene, polypropylene and the like.

High-density polyethylene (HDPE) can be used as polyethylene in consideration of vapor deposition processing, printing processing, bag-making processing, filling suitability, and the like. In addition, in order to improve physical properties such as flexibility, for example, high-density polyethylene (HDPE)/medium-density polyethylene (MDPE)/low-density polyethylene (LDPE)/medium-density polyethylene (MDPE) formed by co-extrusion / A multi-layer construction film such as high density polyethylene (HDPE) may be used as the substrate 1 .

Polypropylene includes oriented polypropylene. In general, polypropylene is broadly classified into homopolymer, random copolymer, block copolymer, and terpolymer, and the polymer type is selected according to the application and required performance. polypropylene is preferred. The heat resistance of the packaging material is improved by using a polypropylene base material with a homopolymer on the outermost surface or by laminating a heat-resistant resin such as nylon on the outermost surface. It can reduce the problem of insufficient seal strength due to pseudo-adhesion and insufficient temperature. In addition, for the purpose of imparting easy adhesion and sealability, a multi-layer structure film in which a copolymer or terpolymer is formed as a skin layer by coextrusion on a homopolymer core layer may be used as the substrate 1. .

The polyolefin film that constitutes the first polyolefin layer may be a stretched film or a non-stretched film. However, from the viewpoint of impact resistance, heat resistance, water resistance, dimensional stability, etc., the polyolefin film may be a stretched film. As a result, the laminate can be more suitably used for hot filling and retort/boiling treatments. The stretching method is not particularly limited, and any method such as inflation stretching, uniaxial stretching, or biaxial stretching may be used as long as a film with stable dimensions can be supplied.
Among them, it is preferable to use biaxially oriented polypropylene with high rigidity and high heat resistance, and as such, the MD heat shrinkage rate when heat treated at 150 ° C. is 20% or less, preferably 15% or less, more preferably 10 % or less can be used.

The thickness of the polyolefin film is not particularly limited. The thickness may be 6 to 200 μm depending on the application, but may be 9 to 50 μm or 12 to 38 μm from the viewpoint of obtaining excellent impact resistance and gas barrier properties.

The resin constituting the base material 1 is not limited to petroleum-derived resin, and may be partly or wholly of a bio-derived resin material (for example, biomass polyethylene using biomass-derived ethylene as a raw material). A method for producing biomass-derived polyethylene is disclosed, for example, in Japanese Patent Publication No. 2010-511634. The base material 1 may include commercially available biomass polyethylene (Green PE manufactured by Braskem, etc.), or mechanically recycled polyolefin made from used polyolefin products or resin (so-called burrs) generated in the manufacturing process of polyolefin products. may contain.

The base material 1 may contain components other than the polyolefin resin. Such components include, for example, polyamide, polyethylene terephthalate, polyvinyl alcohol, biodegradable resin materials (e.g., polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, etc.). is mentioned. The substrate 1 may contain additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, and colorants. The amount of components other than the polyolefin resin in the substrate 1 is preferably 15% by mass or less, more preferably 10% by mass or less, based on the total amount of the substrate layer 1 .

[Gas barrier film 2]
The gas barrier film 2 used in the present invention has a barrier substrate 3 , a base layer 4 , an inorganic oxide layer 5 and a barrier coating 6 . Either one of the base layer 4 and the inorganic oxide layer 5 may be omitted.
The base layer 4 is laminated in contact with the barrier base material 3 , and the inorganic oxide layer 5 is laminated on the surface opposite to the surface of the base layer 4 in contact with the barrier base material 3 . The inorganic oxide layer 5 is laminated in contact with the underlying layer 4 , and the barrier coating 6 is positioned in contact with the surface of the inorganic oxide layer 5 opposite to the surface in contact with the underlying layer 4 . In addition, when the base layer 4 is not provided, the inorganic oxide layer 5 is laminated on the barrier base material 3 . Moreover, when the inorganic oxide layer 5 is not provided, the barrier film 6 is laminated on the base layer 4 .

<Barrier base material>
The barrier base material 3 has two or more resin layers including the base layer 3a. This embodiment has a base layer 3a and a surface layer 3b positioned on one surface of the base layer 3a. The surface layer 3 b constitutes the first surface 3 c of the barrier base material 3 . The barrier base material 3 contains a resin, and each layer of the surface layer 3b and the base layer 3a constituting the barrier base material 3 also contains a resin.

The base layer 3a adjusts the mechanical properties, chemical properties, thermal properties, optical properties, etc. of the barrier base material 3 . Mechanical properties include stiffness, elongation, stiffness, tear strength, impact strength, puncture strength, pinhole resistance and the like. Chemical properties include water vapor barrier properties, gas barrier properties, aroma retention properties, chemical resistance, oil resistance, and the like. Thermal properties include melting point/glass transition point, heat resistance temperature, cold resistance temperature, and heat shrinkage. Optical properties include transparency, glossiness, and the like.

Polyolefin-based resin is preferable as the resin that is the raw material of the base layer 3a from the viewpoint of easy availability and water vapor barrier properties. Polyolefin-based resins include polyethylene, polypropylene, polybutene, and the like. Polypropylene may be homopolymer, random copolymer or block copolymer. A homopolymer is a polypropylene consisting of propylene alone. A random copolymer is a polypropylene in which propylene, the main monomer, and comonomers different from propylene are randomly copolymerized to form a homogeneous phase. A block copolymer is a polypropylene that forms a heterogeneous phase by copolymerizing propylene as a main monomer and the above-mentioned comonomer in a block-like manner or polymerizing in a rubbery state. Any one of these polyolefin-based resins may be used alone, or two or more thereof may be blended and used.

The base layer 3a may contain additives. The additive can be appropriately selected from various known additives. Examples of additives include fillers, antiblocking agents (AB agents), heat stabilizers, weather stabilizers, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes. be done. Any one of these additives may be used alone, or two or more thereof may be used in combination. The content of the additive in the base layer 3a can be appropriately adjusted within a range that does not impair the effects of the present invention.

The base layer 3a may have a single layer structure or a multilayer structure. The thickness of the base layer 3a may be, for example, 3-200 μm, or 6-30 μm.

The surface layer 3b is composed of a polyolefin copolymer resin. Examples of polyolefin copolymer resins include ethylene/propylene copolymers, ethylene/1-butene copolymers, propylene/1-butene copolymers, propylene/pentene copolymers, ethylene/propylene/1-butene copolymers. polymers, ethylene-acrylic acid copolymers, ionomers obtained by cross-linking ethylene-acrylic acid copolymers with metal ions, propylene-acrylic acid copolymers, and the like. It does not matter if it is a coalescence. Any one of these resins may be used alone, or two or more thereof may be blended and used. Since the surface layer 3b is made of a polyolefin-based copolymer resin, the adhesion to any one of the base layer 4, the inorganic oxide layer 5, and the barrier film 6 laminated on the barrier base material 3 is improved.

The surface layer 3b may contain additives. The additive can be appropriately selected from various known additives. Examples of additives include antiblocking agents (AB agents), heat stabilizers, weather stabilizers, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antistatic agents, antifogging agents, pigments, and dyes. Any one of these additives may be used alone, or two or more thereof may be used in combination. The content of the additive in the surface layer 3b can be appropriately adjusted within a range that does not interfere with the effects of the present invention.

When the surface layer 3b contains the AB agent, projections derived from the AB agent are formed on the first surface 3c of the barrier base material 3 . These protrusions prevent the films from sticking together, thereby improving processability in winding, unwinding, and transporting the original film. In particular, the average particle size of the AB agent and its amount of addition affect the size and number of projections on the first surface 3c, so that the number of projections with a Feret diameter of 8 μm or more in the measurement method described later is 20 pieces/mm ² or less. Adjustment is desirable.

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

The average particle size of the AB agent is preferably 0.1 μm or more and 5 μm or less. From the viewpoint of achieving both antiblocking performance and gas barrier performance of the gas barrier film 2, the average particle size of the AB agent is particularly preferably 1 μm or more and 4 μm or less. The average particle size of the AB agent is measured by the Coulter method.

The amount of the AB agent to be added is preferably 0.05 to 0.4 mass % with respect to the total mass of the surface layer 3b, for example. Specifically, the additive amount of the AB agent in the surface layer 3b is determined by the following formula.
Addition amount of AB agent [mass%] = {(I)/100} x {(II)/100} x 100
In the formula, (I) is the concentration (% by mass) of the AB agent in the masterbatch resin chip formed into pellets by adding the AB agent to the resin, stirring it, putting it into an extruder and kneading it, and forming it into pellets by melt extrusion. point to (II) is the concentration (mass% ). Incidentally, when the AB material is added to the base layer 3a, the addition amount is also preferably 0.05 to 0.4% by mass with respect to the total mass of the base layer 3a, and the addition amount can be calculated by the above formula.

The thickness of the surface layer 3b may be, for example, 0.1 to 10 μm, and further may be 0.5 to 5.0 μm.

The barrier substrate 3 is preferably a coextruded film including at least a surface layer 3b and a base layer 3a. The barrier substrate 3 may be a stretched film or an unstretched film.

The barrier substrate 3 preferably comprises a biaxially oriented polypropylene film. Since the biaxially stretched polypropylene film is particularly excellent in water vapor barrier performance, the water vapor barrier property of the gas barrier film 2 is improved by having the biaxially stretched polypropylene film. The biaxially oriented polypropylene film may be a film obtained by processing at least one of homopolymer, random copolymer, block copolymer and the like. The biaxially oriented polypropylene film is preferably a coextruded film.

The base layer 3a may be made of a biaxially oriented polypropylene film, or may be a laminate of a biaxially oriented polypropylene film and another resin film. Other resin films include, for example, 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 films such as polyimide films. A plastic film is mentioned.

The thickness of the barrier base material 3 is not particularly limited, and is appropriately selected depending on the price and application while considering the suitability as a packaging material and the lamination suitability of other films. Practically, the thickness of the barrier base material 3 is preferably 3 μm to 200 μm, more preferably 5 μm to 120 μm, even more preferably 6 μm to 30 μm.

The first surface 3c of the barrier base material 3 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.

When protrusions are formed by the AB agent on the first surface 3c of the barrier base material 3, blocking of the film can be prevented. The barrier film 6 is likely to have film defects that serve as gas permeation paths, and the oxygen barrier property of the gas barrier film 2 may be lowered. However, the first surface of the barrier substrate 3 of the gas barrier film 2 of the present invention is characterized by having 20 projections/mm ² or less with a Feret diameter of 8 μm or more measured by the following measuring method, and film defects are Hard to come by. The first surface 3c of the barrier base material 3 preferably has 17 projections/mm ² or less with a Feret diameter of 8 μm or more, and more preferably 15 projections/mm ² or less with a Feret diameter of 8 μm or more. , the number of protrusions having a Feret diameter of 8 μm or more may be 0/mm ² . Protrusions having a Feret diameter of 8 μm or more often have a height of more than 1 μm from the flat portion of the first surface 3c to the apex of the protrusion, which tends to cause film defects in the oxygen barrier coating. Therefore, when the number of projections having a Feret diameter of 8 μm or more is 20/mm ² or less, film defects are less likely to occur in the underlayer 4, the inorganic oxide layer 5, and the barrier film 6, and the oxygen barrier property of the gas barrier film 2 is improved. easier to do better. The protrusions formed on the first surface of the barrier base material 3 may be derived from the AB agent or may be caused by other factors, and are not particularly limited. In this specification, the number of protrusions on the first surface of the barrier base material 3 is a value measured by the following measuring method.

<Measurement method>
An arbitrary 36.6 mm square area of the barrier base material 3 was illuminated with a white LED line light source from the second surface side opposite to the first surface of the barrier base material 3 at a light source distance of 100 mm and an incident angle of 83°. irradiate with light. A photographed image is acquired by photographing transmitted light at a measurement angle of 90° with a monochrome line camera. An analysis image of 3551 pixels×5684 pixels (2.5×4.0 mm) is cut out from the captured image. Projections having a Feret diameter of ⁸ μm or more are extracted from the clipped analysis image using image analysis software, and the number of projections is counted.

A method for measuring the number of protrusions on the first surface of the barrier base material 3 will be described below with reference to the drawings. First, the measuring device will be described.

(measuring device)
As shown in FIG. 3 , the measuring device 1 for measuring the number of protrusions on the first surface 3 c of the barrier base material 3 includes a sample holder 21 , a light source 23 and a monochrome line camera 25 . The sample holder 21 is placed on a transport device 28 and can move horizontally. A hole 22 is formed in the central portion of the sample holder 21 . The light source 23 is located below the sample holder 21 and installed at a position with a light source distance of 100 mm, and is connected to a light source control device 24 . The monochrome line camera 25 is positioned above the sample holder 21, and the macro lens 26 is attached to the monochrome line camera 25. - 特許庁An image processing device 27 is connected to the monochrome line camera 25 . A transport control unit 29 is connected to the image processing device 27 . The transport controller 29 is connected to the transport device 28 .

The sample holder 21 is not particularly limited as long as it is flat and horizontal, and a known holder may be used. As the light source 23, a visible light white LED line light source is preferable.

The monochrome line camera 25 preferably has 16384 pixels and a sensor size of 3.52 μm per pixel. The monochrome line camera 25 is preferably controlled by the image processing device 27 via a standard interface such as camera link or USB. The image processing device 27 is composed of, for example, a personal computer equipped with a frame grabber or the like connected to the monochrome line camera 25, and image processing software or the like for controlling the frame grabber. Personal computers equipped with frame grabbers and the like and image processing software for controlling the frame grabbers are widely distributed or commercially available, and these can be used as the image processing device 27 . Image processing software includes, for example, public domain software "IMAGEJ" developed by the National Institutes of Health (NIH).

A uniaxial stage or the like driven by a stepping motor is preferably used as the transport device 28 . The conveying device 28 is controlled by a conveying control unit 29 such as the conveying speed, the start of conveying, and the stop of conveying.

(Sample preparation)
Next, a method for measuring the number of protrusions on the first surface of the barrier base material 3 will be described. As shown in FIG. 2, first, the first surface 3c of the barrier substrate 3 is directed toward the monochromatic line camera 25, and the barrier substrate 3 is fixed to the sample holder 21 so that there is no height difference within the plane. . When fixing the barrier base material 3, it is preferable to fix the ends of the barrier base material 3 using OPP tape, masking tape, or the like. The resin base material 20 is fixed to the sample holder 21 so that the image measurement position 30 of the barrier base material 3 is aligned with the punched hole 22 .

(Acquisition of photographed image)
Next, white LED line light is incident from the light source 23 . The light amount of the light source 23 can be adjusted by the light source control device 24 . The amount of incident light L1 is preferably adjusted using the light source control device 24 so that the amount of light at the image measurement position 30 is 442 lux. The incident light L1 from the light source 23 is shifted obliquely by 7° from the vertical direction with the incident angle 13 to the first surface 21 of 83°, and the monochrome line is positioned at the position where the measurement angle 14 is 90° with respect to the first surface 3c. A camera 25 is installed, and the transmitted light L2 transmitted through the image measurement position 30 is photographed by the monochrome line camera 25 via the macro lens 26. - 特許庁At this time, the magnification of the macro lens 26 is 5 times, the F number is 2.8, and the resolution is 0.704 μm. The measurement range of the monochrome line camera 25 at the image measurement position 30 is a 36.6 mm square area, and the effective illumination range of the light source 23 is a 36.6 mm square area or more.

The measurement range of the transmitted light L2 is a 36.6 mm square area of the first surface 3c. The conveying device 28 is moved so that the measurement range is the above region. If the conveying device 28 is a stepping motor or the like, the image processing device 27 receives a pulse signal indicating the conveying speed. The transport speed at which the transport device 28 is moved is preferably set equal to the product of the spatial resolution and the acquisition frequency. The spatial resolution is determined from the sensor size (3.52 μm) of the monochrome line camera 25 and the magnification of the macro lens 26 (5 times). The capturing frequency is the capturing frequency of one line of the monochrome line camera 25 . The transport speed is set equal to the product of the spatial resolution and the acquisition frequency, and the barrier substrate 3 is transported continuously at the image measurement position 30 of the monochrome line camera 25 . At the image measuring position 30, an image of the first surface 3c of the barrier base material 3 is measured by the monochrome line camera 25 and photographed.

Assume that the exposure time of the monochrome line camera 25 is 80 μs. Set the acquisition frequency period to be longer than the exposure time. The barrier base material 3 is conveyed, and a photographed image of 5684 pixels or more is obtained in the conveying direction of the barrier base material 3 .

(Image analysis)
From the obtained photographed image, 3551 pixels at the center corresponding to the direction in which the sensors of the monochrome line camera 25 are arranged (the direction perpendicular to the transport direction of the barrier base material 3) and 5684 pixels in the transport direction are cut out and used as an analysis image. It is also possible to widen the measurement range by extracting 5684 pixels or more in the transport direction. The clipped image for analysis is analyzed using image analysis software.

FIG. 4 shows the principle of detecting minute projections and depressions on the surface of the barrier substrate 3 in this measurement system. With a line camera, when the incident angle θ2 is made smaller than the measurement angle θ1, the projected portion of the image is visualized three-dimensionally with a bright upward direction and a dark downward direction. In the hollow portion, the top and bottom are reversed. It is presumed to be due to refraction similar to that of a spherical lens. Using this tendency, bright particles and dark particles are sorted from the analysis image by brightness, size, and roundness, respectively, binarized, and particles that are bright at the top and dark at the bottom are extracted as protrusions, and the extracted particles to obtain Feret diameter data. FIG. 4 shows a photographed image of the first surface 3c of the barrier base material 3 of the example of the present invention, and an analysis image obtained by extracting the projection portion using the above algorithm. From the Feret diameter data thus extracted, the number of particles having a Feret diameter of 8 μm or more in the image for analysis was counted, and the value converted to the number per mm ² area was defined as the number of projections.

<Underlayer>
The underlying layer 4 is provided between the barrier base material 3 and the inorganic oxide layer 5 or barrier coating 6 . The underlayer 4 is a layer containing an organic polymer as a main component, and is sometimes called a primer layer. By providing the underlayer 4, the film-forming properties and adhesion strength of the inorganic oxide layer 5 or the barrier coating 6 can be improved.

The content of the organic polymer in the underlying layer 4 may be, for example, 70% by mass or more, or may be 80% by mass or more. Examples of organic polymers include polyacrylic resins, polyester resins, polycarbonate resins, polyurethane resins, polyamide resins, polyolefin resins, polyimide resins, melamine resins, and phenol resins. Considering the hot water resistance of the adhesive strength with the adhesive film 6, it is preferable to include at least one of polyacrylic resin, polyol resin, polyurethane resin, polyamide resin, or a reaction product of these organic polymers. Further, the underlayer 4 may contain a silane coupling agent, an organic titanate, or a modified silicone oil.

More preferably, the organic polymer is an organic polymer having a urethane bond produced by a reaction between a polyol having two or more hydroxyl groups at the polymer end and an isocyanate compound, and/or an organic polymer having two or more at the polymer end. Examples include organic polymers containing reaction products of polyols having hydroxyl groups and organic silane compounds such as silane coupling agents or hydrolysates thereof.

Examples of polyols include at least one selected from acrylic polyols, polyvinyl acetals, polystyrene polyols, polyurethane polyols, and the like. The acrylic polyol may be obtained by polymerizing an acrylic acid derivative monomer, or may be obtained by copolymerizing an acrylic acid derivative monomer and another monomer. Acrylic acid derivative monomers include ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of monomers to be copolymerized with acrylic acid derivative monomers include styrene.

The isocyanate compound has the effect of increasing the adhesion between the resin base material 20 and the inorganic oxide layer 5 or the barrier film 6 through the urethane bond formed by reacting with the polyol. That is, the isocyanate compound functions as a cross-linking 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 isocyanate compounds described above may be used singly or in combination of two or more.

Examples of silane coupling agents include vinyltrimethoxysilane, Γ-chloropropylmethyldimethoxysilane, Γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, Γ-methacryloxypropyltrimethoxysilane, and Γ- methacryloxypropylmethyldimethoxysilane and the like. The organosilane compound may be a hydrolyzate of these silane coupling agents. The organic silane compound may contain one of the above-mentioned silane coupling agents and hydrolysates thereof alone or in combination of two or more thereof.

The base layer 4 can be formed on the first surface 3c of the resin substrate 20 using the mixed liquid prepared by blending the above components in an organic solvent in an arbitrary ratio. The mixture includes, for example, tertiary amines, imidazole derivatives, carboxylic acid metal salt compounds, quaternary ammonium salts, quaternary phosphonium salts and other curing accelerators; phenolic, sulfur, and phosphite antioxidants; A leveling agent; a flow control agent; a catalyst; a cross-linking reaction accelerator;

The mixture is applied to the barrier base material 3 using a known printing method such as offset printing, gravure printing, or silk screen printing, or a known coating method such as roll coating, knife edge coating, or gravure coating. can be coated on top. After coating, the base layer 4 can be formed by heating to, for example, 50 to 200° C. and drying and/or curing.

The thickness of the underlayer 4 is not particularly limited, and may be, for example, 0.005 to 5 μm.
The thickness may be adjusted depending on the application or desired properties. The thickness of the underlying layer 4 is preferably 0.01 to 1 μm, more preferably 0.01 to 0.5 μm. If the thickness of the underlayer 4 is 0.01 μm or more, sufficient adhesion strength between the barrier base material 3 and the inorganic oxide layer 5 or the barrier film 30 can be obtained, and the oxygen barrier property is also improved. If the thickness of the base layer 4 is 1 μm or less, it is easy to form a uniform coating surface, and the drying load and manufacturing cost can be suppressed.

<Inorganic oxide layer>
The inorganic oxide layer 5 includes, for example, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, tin oxide, zinc oxide, indium oxide, etc. Aluminum oxide or silicon oxide is particularly excellent in productivity, heat resistance, It is preferable because it is excellent in oxygen barrier properties and water vapor barrier properties in wet heat resistance. In addition, the inorganic oxide layer 5 may contain these 1 types individually or in combination of 2 or more types. The thickness of the inorganic oxide layer 5 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, and if the thickness is 200 nm or less, the manufacturing cost can be kept low. At the same time, it is difficult for cracks to occur due to external forces such as bending and pulling, and deterioration of barrier properties can be suppressed. The inorganic oxide layer 5 can be formed by a known film forming method such as vacuum deposition, sputtering, ion plating, or plasma chemical vapor deposition (CVD).

<Barrier film>
The barrier film 6 may be a known oxygen barrier film formed by a wet coating method. The barrier film 6 is obtained by forming a coating film made of a coating agent on the underlying layer 4 or the inorganic oxide layer 5 by a wet coating method and drying the coating film. A coating film is a wet film, and a film is a dry film.

As the barrier film 6, a film (organic-inorganic composite film) containing at least one of a metal alkoxide, its hydrolyzate, or its reaction product, and a water-soluble polymer is preferable. Furthermore, a film further containing at least one of a silane coupling agent and a hydrolyzate thereof is preferred.

Metal alkoxides and hydrolysates thereof contained in the organic-inorganic composite film include, for example, tetraethoxysilane [SI _{( OC2H5} ) ₄ ] and triisopropoxyaluminum [AL _{(OC3H7)3 ] .} Included are those represented by the formula M(OR)N, as well as hydrolysates thereof. One of these may be contained alone or in combination of two or more.

The total content of at least one of the metal alkoxide and its hydrolyzate or its reaction product in the organic-inorganic composite film is, for example, 40 to 70% by mass. From the viewpoint of further reducing the oxygen permeability, the lower limit of the total content of at least one of the metal alkoxide and its hydrolyzate or its reaction product in the organic-inorganic composite membrane may be 50% by mass. From the same point of view, the upper limit of the total content of at least one of the metal alkoxide and its hydrolyzate or its reaction product in the organic-inorganic composite film may be 65% by mass.

The water-soluble polymer contained in the organic-inorganic composite film is not particularly limited, and examples thereof include polymers such as polyvinyl alcohol, polysaccharides such as starch, methylcellulose, carboxymethylcellulose, and acrylic polyol. From the viewpoint of further improving oxygen gas barrier properties, the water-soluble polymer preferably contains a polyvinyl alcohol-based polymer. The water-soluble polymer has a number average molecular weight of, for example, 40,000 to 180,000.

A polyvinyl alcohol-based water-soluble polymer can be obtained, for example, by saponifying polyvinyl acetate (including partial saponification). This water-soluble polymer may have several tens of percent of acetic acid groups remaining, or may have only several percent of acetic acid groups remaining.

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

Examples of the silane coupling agent and its hydrolyzate contained in the organic-inorganic composite film include silane coupling agents having organic functional groups. Examples of such silane coupling agents and their hydrolysates include ethyltrimethoxysilane, vinyltrimethoxysilane, Γ-chloropropylmethyldimethoxysilane, Γ-chloropropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, Γ -methacryloxypropyltrimethoxysilane, Γ-methacryloxypropylmethyldimethoxysilane, and hydrolysates thereof. One of these may be contained alone or in combination of two or more.

At least one of the silane coupling agent and its hydrolyzate preferably has an epoxy group as an organic functional group. Silane coupling agents having an epoxy group include, for example, Γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. A silane coupling agent having an epoxy group and a hydrolyzate thereof may have an organic functional group different from the epoxy group, such as a vinyl group, an amino group, a methacryl group or a ureyl group.

The silane coupling agent having an organic functional group and its hydrolyzate enhance the oxygen barrier properties of the barrier film 6 and the underlying layer 4 or the inorganic oxide by interaction between the organic functional group and the hydroxyl group of the water-soluble polymer. Adhesiveness with the layer 5 can be further improved. In particular, the epoxy group of the silane coupling agent and its hydrolyzate and the hydroxyl group of polyvinyl alcohol interact to form a barrier film 6 that is particularly excellent in oxygen barrier properties and adhesiveness to the underlayer 4 or the inorganic oxide layer 5. can be formed.

The total content of at least one of the silane coupling agent and its hydrolyzate or its reaction product in the organic-inorganic composite film is, for example, 1 to 15% by mass. From the viewpoint of further reducing the oxygen permeability, the lower limit of the total content of at least one of the silane coupling agent and its hydrolyzate, or its reaction product in the organic-inorganic composite membrane may be 2% by mass. . From the same point of view, the upper limit of the total content of at least one of the silane coupling agent and its hydrolyzate or its reaction product in the organic-inorganic composite film may be 12% by mass.

The organic-inorganic composite film may contain a crystalline inorganic layered compound having a layered structure. Examples of inorganic layered compounds include clay minerals represented by kaolinite group, smectite group, mica group and the like. You may use these 1 type individually or in combination of 2 or more types. The particle size of the inorganic layered compound is, for example, 0.1 to 10 μm. The asbestos ratio of the inorganic layered compound is, for example, 50-5000.

As the inorganic layered compound, a smectite group clay mineral is preferable because a film having excellent oxygen barrier properties and adhesion strength can be formed by intercalation of the water-soluble polymer between the layers of the layered structure. Specific examples of smectite clay minerals include montmoritronite, hectorite, saponite, and water-swellable synthetic mica.

Another preferred example of the barrier film 6 is a film containing a polyvalent metal salt of a carboxylic acid, which is a reaction product of the carboxyl group of the polycarboxylic acid polymer (A) and the polyvalent metal compound (B). (Polyvalent metal salt film of polycarboxylic acid). In this case, even a polycarboxylic acid polyvalent metal salt film formed by applying a coating agent in which the polycarboxylic acid polymer (A) and the polyvalent metal compound (B) are mixed and drying by heating, A coating agent having a polycarboxylic acid polymer (A) as a main component is applied and dried to form an A film, and a coating agent having a polyvalent metal compound (B) as a main component is applied and dried. It may be a polyvalent metal salt film of polycarboxylic acid formed by forming a B film and causing a cross-linking reaction between the A/B layers.

[Polycarboxylic acid polymer (A)]
A polycarboxylic acid polymer is a polymer having two or more carboxy groups in its molecule. Examples of polycarboxylic acid-based polymers include (co)polymers of ethylenically unsaturated carboxylic acids; copolymers of ethylenically unsaturated carboxylic acids and other ethylenically unsaturated monomers; alginic acid, carboxymethyl cellulose and acidic polysaccharides having a carboxyl group in the molecule such as pectin. Examples of ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Ethylenically unsaturated monomers copolymerizable with ethylenically unsaturated carboxylic acids include, for example, ethylene, propylene, saturated carboxylic acid vinyl esters such as vinyl acetate, alkyl acrylates, alkyl methacrylates, and alkyl itaconates. , vinyl chloride, vinylidene chloride, styrene, acrylamide, acrylonitrile and the like. These polycarboxylic acid-based polymers may be used singly or in combination of two or more.

Among the above components, from the viewpoint of the gas barrier properties of the resulting gas barrier film, at least one polymerizable monomer selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, itaconic acid, fumaric acid and crotonic acid. A polymer containing a structural unit derived from a polymer 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. Coalescing 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, It is 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. When the polymer is a copolymer containing structural units other than the above structural units, the other structural units include, for example, ethylenically unsaturated monomers copolymerizable with the aforementioned ethylenically unsaturated carboxylic acids. Structural units derived from mers and the like are included.

The number average molecular weight of the polycarboxylic acid polymer is preferably in the range of 2,000 to 10,000,000, more preferably 5,000 to 1,000,000. If the number average molecular weight is less than 2,000, the resulting gas barrier film cannot achieve sufficient water resistance, and the gas barrier properties and transparency may deteriorate or whitening may occur due to moisture. On the other hand, if the number-average molecular weight exceeds 10,000,000, the viscosity of the coating agent used to form the barrier film 6 increases, which may impair the coatability. In addition, the said number average molecular weight is the number average molecular weight of polystyrene conversion calculated|required by the gel permeation chromatography (GPC).

When a coating agent containing a polycarboxylic acid polymer (A) as a main component is applied and dried to form the A film, and then the B film is formed, the polycarboxylic acid polymer is one of the carboxy groups. The part may be neutralized in advance with a basic compound. By partially neutralizing the carboxy groups of the polycarboxylic acid polymer in advance, the water resistance and heat resistance of the A film can be further improved. The basic compound is preferably at least one basic compound selected from the group consisting of polyvalent metal compounds, monovalent metal compounds and ammonia. As the polyvalent metal compound, compounds exemplified in the description of the polyvalent metal compound (B) described later can be used. Examples of monovalent metal compounds include sodium hydroxide and potassium hydroxide.

Various additives can be added to the coating agent containing the polycarboxylic acid-based polymer (A) as a main component. agents, antiblocking agents, antistatic agents, dispersants, surfactants, softeners, stabilizers, film formers, thickeners and the like.

The solvent used for the coating agent containing the polycarboxylic acid polymer (A) as a main component is preferably an aqueous medium. Aqueous media include water, water-soluble or hydrophilic organic solvents, or mixtures thereof. The aqueous medium usually contains water or water as a main component. The content of water in the aqueous medium is preferably 70% by mass or more, 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 acetonitriles. mentioned.

[Polyvalent metal compound (B)]
The polyvalent metal compound is not particularly limited as long as it is a compound that reacts with the carboxyl groups of the polycarboxylic acid-based polymer to form a polyvalent metal salt of polycarboxylic acid, such as zinc oxide particles, magnesium oxide particles, magnesium methoxide. , copper oxide, calcium carbonate, and the like. These may be used singly or in combination. Zinc oxide is preferable from the viewpoint of the oxygen barrier properties of the barrier coating.

Zinc oxide is an inorganic material having ultraviolet absorption ability, and the average particle size of zinc oxide particles is not particularly limited, but from the viewpoint of gas barrier properties, transparency, and coatability, the average particle size is preferably 5 μm or less. , is more preferably 1 μm or less, and particularly preferably 0.1 μm or less.
When a coating agent containing a polyvalent metal compound (B) as a main component is applied and dried to form a B film, if necessary, in addition to zinc oxide particles, within a range that does not impair the effects of the present invention, It may contain various additives. Examples of the additive include a resin soluble or dispersible in the solvent used for the coating agent, a dispersant soluble or dispersible in the solvent, a surfactant, a softening agent, a stabilizer, a film-forming agent, a thickener, and the like. may contain.

Among the above, it is preferable to contain a resin that is soluble or dispersible in the solvent used for the coating agent. This improves the coatability and film formability of the coating agent. Examples of such resins include alkyd resins, melamine resins, acrylic resins, urethane resins, polyester resins, phenol resins, amino resins, fluorine resins, epoxy resins, and isocyanate resins.

Moreover, it is preferable to contain a dispersant that is soluble or dispersible in the solvent used for the coating agent. This improves the dispersibility of the polyvalent metal compound. As the dispersant, an anionic surfactant or a nonionic surfactant can be used. The surfactants include (poly)carboxylates, alkyl sulfates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylsulfosuccinates, alkyldiphenyletherdisulfonates, alkylphosphates, aromatic Phosphate ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, alkylallyl sulfate, polyoxyethylene alkyl phosphate, sorbitan alkyl ester, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid various surfactants such as 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, polyoxyethylene alkylamines, etc. be done. These surfactants may be used alone or in combination of two or more.

When the coating agent containing the polyvalent metal compound (B) as a main component contains an additive, the mass ratio of the polyvalent metal compound to the additive (polyvalent metal compound: additive) is 30: It is preferably in the range of 70-99:1, preferably in the range of 50:50-98:2.

Examples of solvents used in coating agents containing the polyvalent metal compound (B) as a main component include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, N-propyl alcohol, N-butyl alcohol, N-pentyl alcohol, dimethyl alcohol, Foxide, dimethylformamide, dimethylacetamide, toluene, hexane, heptane, cyclohexane, acetone, methyl ethyl ketone, diethyl ether, dioxane, tetrahydrofuran, ethyl acetate, butyl acetate. Moreover, these solvents may be used individually by 1 type, or may be used in mixture of 2 or more types. Among these, methyl alcohol, ethyl alcohol, isopropyl alcohol, toluene, ethyl acetate, methyl ethyl ketone, and water are preferred from the viewpoint of coatability. Moreover, from the viewpoint of manufacturability, methyl alcohol, ethyl alcohol, isopropyl alcohol, and water are preferred.

In the case where a coating agent obtained by mixing the polycarboxylic acid polymer (A) and the polyvalent metal compound (B) is applied and dried to form a polyvalent metal salt film of polycarboxylic acid, the polycarboxylic acid-based The polymer (A), the above-mentioned polyvalent metal compound (B), and water or alcohol as a solvent are mixed with a resin or dispersant that can be dissolved or dispersed in the solvent, and if necessary, additives, As a coating agent, a polyvalent metal salt film of polycarboxylic acid can be formed by applying and drying by a known coating method. Coating methods include, for example, 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, A curtain coat method etc. are mentioned.

The thickness of the barrier coating 6 is set according to the required oxygen barrier properties, and may be, for example, 0.05 to 5 μm. The thickness of the barrier film 6 is preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm. When the barrier film 6 has a thickness of 0.05 μm or more, it is easy to obtain sufficient oxygen barrier properties. If the thickness of the barrier film 6 is 1 μm or less, it is easy to form a uniform coated surface, and the drying load and manufacturing cost can be suppressed.

In the barrier film 6, the gas barrier film having the organic-inorganic composite film or the polyvalent metal salt film of polycarboxylic acid exhibits excellent oxygen barrier properties even after boiling treatment or retort sterilization treatment. When laminated with a sealant film, it has sufficient adhesion strength and seal strength even as a packaging material for boiling and retort processing.In addition, it has transparency, bending resistance, and stretching resistance that are not found in metal foils and metal deposition films. There are advantages such as excellent performance and no risk of generating harmful substances such as dioxin.
Moreover, the barrier film 6 may be composed of a plurality of layers.

[Method for producing gas barrier film]
The gas barrier film 2 is formed by forming either one of the underlayer 4 and the inorganic oxide layer 50 or both the underlayer 4 and the inorganic oxide layer 5 on the first surface 3c of the barrier substrate 3, and then forming the underlayer. 4 or by forming a barrier film 6 on the inorganic oxide layer 5 . The method for producing the gas barrier film 2 of the present invention includes, for example, a selection step, a base layer forming step, an inorganic oxide layer forming step, and a barrier film forming step.

As the sorting step, for example, a step of sorting out the resin base raw fabric having 20 pieces/mm ² or less projections with a Feret diameter of 8 μm or more on the surface as the barrier base material 3 . The number of protrusions on the surface of the resin base raw material is measured by the same method as the method for measuring the number of protrusions on the first surface 3c of the barrier base material 3 described above. As the barrier base material 3, a commercially available product may be used, or one manufactured by a known method may be used.

In the base layer forming step, for example, a coating agent is applied to at least the first surface 3c of the barrier base material 3 by a wet coating method to form a coating film, and the coating film is dried (solvent is removed) to form a base layer. A step of forming the stratum 4 may be mentioned. As a method for applying the coating agent, a known wet coating method can be used. Wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. As a method for drying a coating film made of a coating agent, a known drying method such as hot air drying, hot roll drying, infrared irradiation, or the like can be used. Drying conditions include, for example, 90° C. for 10 seconds.

As the inorganic oxide layer forming step, for example, the above-described vacuum deposition method, sputtering method, ion plating method, or plasma vapor deposition method (CVD ) or the like to form the inorganic oxide layer 5 .

As a barrier film forming step, for example, a coating agent is applied on the underlayer 4 or the inorganic oxide layer 5 by a wet coating method to form a coating film, and the coating film is dried (solvent is removed). a step of forming the barrier film 6 by As a method for applying the coating agent, a known wet coating method can be used. Wet coating methods include roll coating, gravure coating, reverse coating, die coating, screen printing, and spray coating. As a method for drying a coating film made of a coating agent, a known drying method such as hot air drying, hot roll drying, infrared irradiation, or the like can be used. Drying conditions include, for example, 90° C. for 10 seconds.
The barrier film 6 may be formed by applying and drying once, or may be formed by repeating applying and drying a plurality of times using the same type of coating agent or a different type of coating agent.

When the production method of the gas barrier film 2 includes a selection step, the barrier substrate 3 having 20/mm ² or less projections with a Feret diameter of 8 μm or more on the surface can be efficiently applied. Therefore, a gas barrier film with improved oxygen barrier properties can be efficiently produced by including the sorting step. In addition, by including the sorting step, the gas barrier film 100 with good printability can be efficiently produced.

The gas barrier film 2 may further have a printed layer, a protective layer, a light shielding layer, an adhesive layer, a heat-sealable heat-sealable layer, other functional layers, and the like, if necessary. When the gas barrier film 2 has a heat-sealable heat-sealable layer, this heat-sealable layer is arranged on at least one outermost layer of the gas barrier film 2 . Since the gas barrier film 2 has a heat-sealable layer, the gas barrier film 2 can be sealed by heat sealing (for example, a package or a lid). The heat-sealable layer is, for example, a laminate obtained by forming the base layer 4, the inorganic oxide layer 5, and the barrier film 6 of the present embodiment on one or both sides of the barrier base material 3. Polyurethane-based or polyester-based Lamination can be performed by a known dry lamination method, extrusion lamination method, or the like using a known adhesive such as a polyether-based adhesive.

[Sealant layer]
The sealant layer 7 is a layer that imparts sealing properties by heat sealing to the packaging material 10, and contains polyolefin. Also, the content of polyolefin in the sealant layer 7 is, for example, 70% by mass or more, and may be 40 to 90% by mass. When the polyolefin content of the sealant layer 7 is 70% by mass or more, the polyolefin content of the packaging material 10 (based on the total amount of the packaging material 10) can be easily made 90% by mass or more, and a monomaterial can be easily realized.

As a resin material for forming the sealant layer 7, a polyethylene resin or a polypropylene resin can be used.
If the sealant layer 7 is polyethylene, linear low density polyethylene (LLDPE) can be used. Also, for the purpose of imparting rigidity, the gas barrier film 2 is made of high density polyethylene (HDPE) or medium density polyethylene (MDPE), and the content side is made of low density polyethylene (LDPE). film can also be used.
Furthermore, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE), linear low density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α olefin copolymer, ethylene- Ethylene-based resins such as (meth)acrylic acid copolymers, blended resins of polyethylene and polybutene, homopolypropylene resins (PP), propylene-ethylene random copolymers, propylene-ethylene block copolymers, propylene-α-olefins Polypropylene-based resins such as copolymers can be used alone, or they can be laminated by blending or co-extrusion. The thickness of the sealant layer 7 is, for example, 40-150 μm. As the sealant layer 7, biomass-derived polyolefin may be used. For example, a sealant film partially or wholly containing biomass polyethylene using ethylene as a raw material may be used. Such a sealant film is disclosed, for example, in JP-A-2013-177531. The sealant layer 7 may also contain mechanically recycled polyolefin made from used polyolefin products or resins (so-called burrs) generated during the manufacturing process of polyolefin products.

A packaging bag can be produced by arranging the sealant layers 7 of the packaging material 10 facing each other and heat-sealing at least a part of the periphery thereof. Examples of packaging bags include pillow bags, standing pouches, three-side seal bags, four-side seal bags, and the like. At this time, by using a heat-resistant base material, pseudo-adhesion during bag making (a defect in which parts that should not be adhered stick to each other) and a sufficient bonding temperature are achieved because the difference in melting point between the base material and the sealant is small. It is possible to prevent insufficient sealing strength due to lack of time.
In addition to the packaging bag, the packaging material 10 may include, for example, packaging products such as containers, sheet molded products such as decorative sheets and trays, optical films, resin plates, various label materials, lid materials, and various materials such as laminated tubes. It can be applied to the application.

An adhesive layer 8 may be provided between the substrate 1 and the gas barrier film 2 and between the gas barrier film 2 and the sealant layer 7 .
The adhesive constituting the adhesive layer 8 can be selected according to the bonding method, and for example, a urethane-based adhesive, a polyester-based adhesive, or the like can be used. By providing the adhesive layer 8, the interlayer adhesion between the base material 1 and the sealant layer 7 is enhanced to prevent delamination, and the pressure resistance and impact resistance of the pouch can be maintained. For example, a dry lamination method that uses adhesives such as one-component curing or two-component curing urethane adhesives, a non-solvent dry lamination method that uses non-solvent adhesives, and heats polyolefin resins such as polyethylene and polypropylene. Examples include an extrusion lamination method in which the material is melted, extruded in the form of a curtain, and laminated.
The adhesive layer 8 preferably does not contain chlorine. Since the adhesive layer 8 does not contain chlorine, it is possible to prevent the adhesive and the regenerated resin from being colored and the generation of odor due to the heat treatment. Using an adhesive containing a biomass material as the adhesive layer 8 is preferable from the viewpoint of environmental friendliness. From the viewpoint of environmental consideration, it is preferable to use a method that does not use a solvent for adhesion.

The packaging material 10 may comprise a printed layer. The printed layer can be provided on the outermost surface of the packaging material on the substrate 1, between the substrate 1 and the gas barrier film 2, and between the gas barrier film 3 and the sealant layer 7. When a printed layer is provided on the gas barrier film 2, it is preferably provided on the barrier base material 3 on the side opposite to the surface on which the barrier film 6 is formed.

The print layer is formed using an ink obtained by adding various pigments, plasticizers, desiccants, stabilizers, etc. to a binder resin such as urethane, acrylic, nitrocellulose, or rubber. layer. Characters, patterns, and the like can be displayed on the printed layer.

The ink may be water-based ink or oil-based ink, but water-based ink is preferred. Since water-based ink uses water or alcohol as a solvent, it can further reduce environmental load. In particular, when the adhesive composition is a non-solvent type adhesive composition, use of a water-based ink can significantly reduce the environmental load. In addition, the ink may or may not be biomass ink, but biomass ink is preferable from the viewpoint of reducing the environmental load. Here, the biomass ink refers to the above-described binder resin derived from biomass.
As the printing method, for example, known printing methods such as offset printing, gravure printing, flexographic printing, silk screen printing, and inkjet printing can be used.

<Effect>
In the gas barrier film 2 used in the present invention, the resin layer forming the first surface 3c is made of a polyolefin copolymer resin, and the first surface has 20 protrusions with a Feret diameter of 8 μm or more measured by the above-described measuring method. Either one of the base layer 4 or the inorganic oxide layer 50, or both the base layer 4 and the inorganic oxide layer 5 are laminated on the first surface 3c of the barrier base material 3 having a particle size/mm ² or less. A protective film 6 is laminated. The gas barrier film 2 of the present invention comprises a barrier substrate 3 having a surface layer 3b made of a polyolefin copolymer resin and having 20 projections/mm ² or less with a Feret diameter of 8 μm or more, an underlayer 4 or an inorganic oxide layer 5. Since the barrier film 6 is formed via either or both of the can improve adhesion. In addition, since the gas barrier film 2 of the present invention does not require excessive thickness of the base layer 4, the inorganic oxide layer 5, and the barrier coating 6, productivity can be improved and the amount of materials used can be reduced. be done.
Therefore, by using this gas-barrier film 2 as a packaging material, it has sufficient lamination strength as a packaging material, and the quality retention of the contents can be improved at a low cost.

The packaging material of the present invention stably exhibits excellent gas barrier properties, and exhibits excellent gas barrier properties even after retort treatment. In addition, the surface condition of the base film can be easily grasped, the quality can be stabilized even if the barrier film is thinned, and the cost of raw materials can be reduced. Furthermore, it has sufficient lamination strength even after retorting. The packaging material of the present invention can be suitably used as a packaging material for boiling treatment and retort treatment, and can enhance the quality retention of contents. In particular, by using biaxially oriented polypropylene as the base material and using non-oriented polypropylene as the sealant layer, the polyolefin content of the packaging material 10 (based on the total amount of the packaging material 10) is reduced to 90 mass while being suitable for high temperature processing. % or more, and it is possible to realize a mono-material.

1 base material 2 gas barrier film layer 3 barrier base material 3a base layer 3b surface layer 3c first surface 3d second surface 4 base layer 5 inorganic oxide layer 6 barrier film 7 sealant 8 adhesive 10 packaging material 20 measuring device 21 sample holder 22 Vent hole 23 Light source 24 Light source control device 25 Monochrome line camera 26 Macro lens 27 Image processing device 28 Transport device 29 Transport control unit 30 Image measurement position 31 Incident angle 32 Measurement angle L1 Incident light L2 Transmitted light

Claims (14)

A packaging material comprising at least a substrate, a gas barrier film layer and a sealant layer,
The barrier film layer comprises a barrier base material and a barrier film formed on a first surface side, which is one surface of the barrier base material,
having at least one of an underlying layer and an inorganic oxide layer between the barrier base material and the barrier coating;
The barrier base material has two or more resin layers,
Among 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 having a Feret diameter of 8 μm or more measured by the following measuring method. /mm ² or less.
<Measurement method>
An arbitrary area of 36.6 mm square on the first surface of the resin substrate is irradiated with light using a white LED line light source at a light source distance of 100 mm and an incident angle of 83 °, and transmitted light at a measurement angle of 90 ° is measured with a monochrome line camera. A photographed image is obtained by photographing, an analysis image of 3551 pixels×5684 pixels (2.5×4.0 mm) is cut out from the photographed image, and projections having a Feret diameter of 8 μm or more in the analysis image are counted. The packaging material according to claim 1, wherein the barrier base material is a polyolefin resin. The packaging material according to any one of claims 1 and 2, wherein the base layer has a thickness of 0.01 to 1 µm. The underlayer contains an organic polymer as a main component,
4. Any one of claims 1 to 3, 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. packaging materials as described in . The packaging material according to any one of claims 1 to 4, wherein the inorganic oxide layer has a thickness of 1 to 200 nm. The packaging material according to any one of claims 1 to 5, wherein said inorganic oxide layer is aluminum oxide or silicon oxide. The packaging material according to any one of claims 1 to 6, wherein the barrier film has a thickness of 0.05 to 1 µm. 8. The barrier coating according to any one of claims 1 to 7, wherein the barrier coating comprises at least one of a metal alkoxide, a metal alkoxide hydrolyzate, and a metal alkoxide reaction product, and a water-soluble polymer. Packaging material as described. 9. The packaging material of claim 8, wherein the barrier coating comprises at least one of a silane coupling agent, a hydrolyzate of a silane coupling agent, and a reaction product of a silane coupling agent. 8. Any one of claims 1 to 7, wherein the barrier coating comprises a polyvalent metal salt of a carboxylic acid that is a reaction product of a carboxy group of the polycarboxylic acid polymer (A) and the polyvalent metal compound (B). or the packaging material according to item 1. Packaging material according to any one of the preceding claims, wherein the substrate is biaxially oriented polypropylene. 12. The packaging material according to claim 11, wherein the MD heat shrinkage of the biaxially oriented polypropylene base material when heat-treated at 150[deg.] C. is 20% or less. 12. The packaging material of Claim 11, wherein the sealant layer is unoriented polypropylene. A packaging bag obtained by arranging the sealant layers of the packaging material according to any one of claims 1 to 13 so as to face each other and heat-sealing at least a part of the peripheral edge thereof.

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