Laminated films and packaging materials

Abstract

To provide a laminated film that is a film permitting formation of a laminate constitution constituted almost completely of a single type of resin having little environmental impact, made up primarily of polypropylene film, and that has gas barrier properties, adhesiveness, and further required performance such as processability as demanded for packaging materials.SOLUTION: A laminated film comprising a coating layer including a polyvinyl alcohol-based copolymer and an inorganic lamellar compound on at least one surface of a substrate film, the laminated film being characterized in that it satisfies the following requirements (a) to (d): (a) The substrate film is a stretched film employing a propylenic resin. (b) The amount of adhesion of the coating layer is 0.10 g / m2 or more and 0.50 g / m2 or less. (c) In the total reflection infrared absorption spectrum of the laminated film, the ratio (P1 / P2) of the peak intensity (P1) having maximum absorption in the 1040±10 cm-1 region to the peak intensity (P2) having maximum absorption in the 3300±10 cm-1 region is within a range of 3.0 to 25.0. (d) The thermal shrinkage of the laminated film when heated at 150°C×5 minutes is 10% or less in both the MD direction and the TD direction.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a gas barrier laminated film. More specifically, it relates to a gas barrier coated film that has low environmental impact during manufacturing and disposal, and combines excellent gas barrier performance with sufficient adhesive strength for packaging materials and dimensional stability during secondary processing. [Background technology]

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

[0003] The performance requirements for the aforementioned environmentally friendly packaging materials include: (1) being made from recyclable materials, (2) having gas barrier properties that can block various gases and extend the shelf life, and (3) having a laminate structure that has a low environmental impact (for example, not using organic solvents, using a small amount of material, and being recyclable through monomaterialization).

[0004] In recent years, attention has been focused on the use of polypropylene film in order to enable the above (2) and (3). Polypropylene film is widely used in a variety of applications, such as packaging for food and various products, electrical insulation, and surface protection films. Due to its molecular structure, polypropylene film can exhibit high water vapor barrier properties. Furthermore, since polypropylene-based and polyethylene-based heat-seal resins are commonly used as sealants to bond with surface substrate films, for example, by using polypropylene film as the surface substrate and an unstretched polypropylene sheet as the sealant, it is possible to achieve monomaterial packaging as a whole while maintaining gas barrier properties, enabling environmentally friendly packaging designs that are easy to recycle.

[0005] However, regarding the gas barrier properties mentioned in (2) above, although polypropylene films have water vapor barrier properties, they are not sufficient compared to, for example, transparent inorganic vapor-deposited polyester films which are generally considered to have excellent water vapor barrier properties, and they also have the problem of having very poor oxygen barrier properties. In response to this, films have been used in which polypropylene films are laminated with polymer resin compositions that are generally said to have relatively high oxygen barrier properties, such as polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyvinylidene chloride resin, and polyacrylonitrile (see, for example, Patent Documents 1 to 3).

[0006] However, gas barrier coating films using the above-mentioned polymer resin compositions of polyvinyl alcohol or ethylene vinyl alcohol copolymers exhibited high humidity dependence, resulting in a decrease in gas barrier properties under high humidity conditions. Furthermore, while polyvinylidene chloride resin and polyacrylonitrile showed low humidity dependence, they had problems with insufficient absolute barrier values ​​and a high risk of generating harmful substances during disposal and incineration.

[0007] As a method to improve the humidity dependence of vinyl alcohol-based resins, a gas barrier coating film has been proposed in which a coating layer of vinyl alcohol-based resin mixed with a silane-based crosslinking agent is laminated. In this case, because the vinyl alcohol-based resin is crosslinked by silanol groups, it exhibits low humidity dependence and good gas barrier properties (see, for example, Patent Documents 4 and 5).

[0008] However, these gas barrier coating films require sufficient heat treatment to crosslink, and when the base material is polypropylene film, they cannot satisfy sufficient properties as packaging materials due to deterioration of mechanical properties and thermal wrinkling during processing. Furthermore, the heat treatment during processing requires a large amount of thermal energy, making it undesirable from an environmental perspective. In addition, their water vapor barrier performance was still insufficient.

[0009] On the other hand, as a means for further improving the barrier performance, a gas barrier coating film in which a resin layer containing inorganic layered particles having a specific particle size and aspect ratio is laminated on a vinyl alcohol-based resin has been proposed. In this case, the inorganic layered particles dispersed in the resin layer cause a bypass effect of gas molecules, showing good gas barrier properties (see, for example, Patent Documents 6 and 7).

[0010] However, in many of these gas barrier coating films, the inorganic layered particles are not uniformly dispersed in the coating film. As a result, the adhesion to the base film is inhibited, and the laminate strength may decrease. Also, sufficient satisfactory performance has not been obtained in terms of improving both the oxygen barrier property and the water vapor barrier property.

[0011] In order to exhibit sufficient barrier performance, all of the above-described barrier coating layers need to be laminated with a film thickness of at least 0.5 μm or more. When the film thickness of the coating layer is thick, recycling may become difficult, and it is not suitable from the viewpoint of monomerization using a single material. Furthermore, in processing steps such as printing, there are problems of printing defects due to coating unevenness and irregularities.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0013] In addition to the insufficient barrier performance in the above Patent Documents 1 to 3, designs considering the environment have not been studied. In Patent Documents 4 and 5, there has been no study on appropriately coating a polypropylene film, and the water vapor barrier property has not been fully discussed either. In Patent Document 6, improvement of adhesiveness and water vapor barrier property have not been studied. In Patent Document 7, oxygen barrier property has not been studied. Also, in none of the documents, improvement of processability by thinning the coating layer and consideration for the environment have been made. That is, as the performance required for the above-mentioned environmentally friendly packaging material, (1) including a recyclable material as a constituent material, (2) having gas barrier performance capable of blocking various gases and extending the expiration date, and (3) having a laminate structure that is easy to recycle and has a low environmental load (monomaterialization), there has been no material that satisfies all three points conventionally.

[0014] The present invention has been made against the background of such problems of the prior art. That is, the problem of the present invention is to provide a film capable of forming a laminate structure composed of almost a single resin type with a low environmental load mainly composed of a polypropylene film, and a laminated film having necessary performances such as gas barrier property, adhesiveness, and further processing suitability required for a packaging material. Also, from the viewpoint of improving processing suitability, by using a polypropylene film with a small heat shrinkage rate, the quality during printing and laminating can be further improved.

Means for Solving the Problems

[0015] The inventors of this invention have discovered that by laminating a predetermined coating layer on a polypropylene film to match the required performance, the gas barrier performance can be greatly improved, and furthermore, a film with a low environmental impact and reduced wrinkles and sagging during secondary processing such as printing and lamination can be provided, resulting in a high-quality film.

[0016] In other words, the present invention consists of the following configuration. 1. A laminated film comprising a base film and a coating layer having a polyvinyl alcohol copolymer and an inorganic layered compound on at least one side thereof, wherein the laminated film satisfies the following requirements (a) to (d). (a) The base film is a stretched film made of a propylene copolymer. (b) The amount of the coating layer is 0.10 g / m 2 More than 0.50g / m 2 The following conditions must be met: (c) In the total reflection infrared absorption spectrum of the laminated film, 1040 ± 10 cm⁻¹ -1 The peak intensity (P1) has an absorption maximum in the region and is 3000±10cm. -1 Absorption maximum in the region The ratio of peak intensities (P1 / P2) with the specified peak intensity (P2) must be within the range of 3.0 to 25.0. (d) The heat shrinkage rate of the laminated film at 150°C for 5 minutes is 10% or less in both the MD direction and the TD direction. 2. The laminated film according to claim 1, characterized in that the arithmetic mean roughness of the coating layer on the laminated film in a 2 μm square area is in the range of 2.0 to 8.0 nm. 3. The laminated film in 1. or 2., characterized in that the heat shrinkage rate of the laminated film at 120°C for 5 minutes is 1% or less in both the MD direction and the TD direction. 4. The oxygen permeability of the laminated film under a 23°C × 65%RH environment is 50 ml / m². 2 • Water vapor transmission rate of 4 g / m³ at d MPa or less and under 4°C × 90% RH conditions. 2A laminated film according to any one of 1. to 3., characterized in that it is less than or equal to d. 5. The laminated film according to any one of claims 1 to 4, characterized in that the inorganic layered compound of the coating layer contains a montmorillonite-based compound as a constituent component. 6. A packaging material comprising a laminated film described in any of 1. to 5. above, with an olefin-based sealant layer laminated on one side. [Effects of the Invention]

[0017] Through this technology, the inventors have made it possible to provide a laminated film that possesses the necessary properties such as barrier properties, adhesiveness, and processability required for packaging materials, while also being environmentally conscious. [Modes for carrying out the invention]

[0018] The present invention will be described in detail below. [Base film layer] In the present invention, the propylene-based resin stretched film used as the base film is preferably a biaxially oriented film. Known biaxially oriented polypropylene resin films can be used as the biaxially oriented polypropylene resin film, and the raw materials and mixing ratios are not particularly limited. For example, it may be a polypropylene homopolymer (propylene homopolymer), a random copolymer or block copolymer with propylene as the main component and one or more α-olefins selected from ethylene, butene, pentene, hexene, etc., or a mixture of two or more of these polymers. Furthermore, known additives such as antioxidants, antistatic agents, and plasticizers may be added for the purpose of modifying physical properties, and for example, petroleum resins or terpene resins may be added.

[0019] Furthermore, the biaxially oriented polypropylene resin film used in the present invention may be a single-layer film, or a laminated film in which multiple resin films including the biaxially oriented polypropylene resin film are laminated together. In the case of a laminated film, the type of laminate, the number of layers, the lamination method, etc., are not particularly limited and can be arbitrarily selected from known methods depending on the purpose.

[0020] In the present invention, the polypropylene resin constituting the base film is preferably a propylene homopolymer that is substantially free of comonomers, and even if it contains comonomers, the amount of comonomers is preferably 0.5 mol% or less. The upper limit of the amount of comonomers is more preferably 0.3 mol%, and even more preferably 0.1 mol%. Within this range, crystallinity is improved, the thermal shrinkage rate at high temperatures is reduced, and the heat resistance is improved. However, within a range that does not significantly reduce crystallinity, trace amounts of comonomers may be included.

[0021] The polypropylene resin constituting the base film preferably contains a propylene homopolymer obtained solely from propylene monomers, and most preferably, even if it is a propylene homopolymer, it does not contain heterogeneous bonds such as head-to-head bonds.

[0022] From a practical standpoint, the lower limit of xylene-soluble content in the polypropylene resin constituting the base film is preferably 0.1% by mass. The upper limit of xylene-soluble content is preferably 7% by mass, more preferably 6% by mass, and even more preferably 5% by mass. Within these ranges, crystallinity is improved, the thermal shrinkage rate at high temperatures is reduced, and heat resistance is improved.

[0023] In the present invention, the lower limit of the melt flow rate (MFR) (230°C, 2.16 kgf) of the polypropylene resin is preferably 0.5 g / 10 min. More preferably, the lower limit of the MFR is 1.0 g / 10 min, even more preferably 2.0 g / 10 min, particularly preferably 4.0 g / 10 min, and most preferably 6.0 g / 10 min. Within this range, the mechanical load is small, and extrusion and stretching are easy. The upper limit of the MFR is preferably 20 g / 10 min. More preferably, the upper limit of the MFR is 17 g / 10 min, even more preferably 16 g / 10 min, and particularly preferably 15 g / 10 min. Within this range, stretching is easy, thickness variations are reduced, the stretching temperature and heat setting temperature can be increased, the thermal shrinkage rate is smaller, and the heat resistance is improved.

[0024] The aforementioned base film may be a uniaxially oriented film in the longitudinal direction (MD direction) or transverse direction (TD direction) from the viewpoint of heat resistance, but a biaxially oriented film is preferred. In the present invention, by stretching at least uniaxially, a film with high heat resistance can be obtained, which has a low thermal shrinkage rate at high temperatures that could not be expected with conventional polypropylene films. Examples of stretching methods include simultaneous biaxial stretching and sequential biaxial stretching, but sequential biaxial stretching is preferred from the viewpoint of providing good flatness, dimensional stability, and thickness uniformity.

[0025] In the sequential biaxial stretching method, polypropylene resin is heated and melted in a single-screw or twin-screw extruder to a resin temperature of 200°C to 280°C, formed into a sheet using a T-die, and extruded onto a chill roll at a temperature of 10°C to 100°C to obtain an unstretched sheet. Next, it is roll-stretched in the longitudinal direction (MD direction) at 120°C to 165°C to 3.0 to 8.0 times its original size. Subsequently, after preheating in a tenter, it can be stretched in the transverse direction (TD direction) at a temperature of 155°C to 175°C to 4.0 to 20.0 times its original size. Furthermore, after biaxial stretching, a heat-setting treatment can be performed at a temperature of 165°C to 175°C while allowing for a relaxation of 1% to 15%.

[0026] In the present invention, the base film used preferably contains particles to form protrusions on the film surface in order to impart handling properties (e.g., windability after lamination). Examples of particles to be imparted to the film include inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, and alumina, and heat-resistant polymer particles such as acrylic, PMMA, nylon, polystyrene, polyester, and benzoguanamine-formaldehyde condensate. From the viewpoint of transparency, the particle content in the film is preferably low, for example, preferably 1 ppm to 1000 ppm. Furthermore, from the viewpoint of transparency, it is preferable to select particles with a refractive index close to that of the resin used. In addition, the film may contain antioxidants, ultraviolet absorbers, antistatic agents, dyes, lubricants, nucleating agents, adhesives, antifogging agents, flame retardants, antiblocking agents, inorganic or organic fillers, etc., in order to impart various functions as needed.

[0027] Other materials besides the polypropylene resin used in this invention may be incorporated into the film, to the extent that they do not impair the objectives of this invention, for purposes such as improving the mechanical properties of the base film and the adhesion to the ink layer and adhesive layer laminated on the gas barrier coating layer. Examples include polypropylene resins other than those mentioned above, random copolymers which are copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers.

[0028] In the present invention, the thickness of the base film can be arbitrarily set according to each application, but the lower limit is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. On the other hand, the upper limit of the thickness is preferably 300 μm or less, more preferably 250 μm or less, even more preferably 200 μm or less, and particularly preferably 100 μm or less. If the thickness is too thin, handling is likely to be poor. On the other hand, if the thickness is too thick, not only are there cost issues, but when stored wound in a roll, poor flatness due to curling is likely to occur.

[0029] The haze of the polypropylene film used as the base material of the present invention is preferably transparent from the viewpoint of visibility of the contents, specifically preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less. The haze tends to worsen when, for example, the stretching temperature or heat setting temperature is too high, the cooling roll (CR) temperature is high and the cooling rate of the stretched raw material sheet is slow, or there is too much low molecular weight, so it can be controlled within the above range by adjusting these factors. Here, the haze was evaluated in accordance with JIS K7136, using a turbidimeter (NDH2000, manufactured by Nippon Denshoku).

[0030] Furthermore, the base film layer in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, etc., as long as the objectives of the present invention are not impaired, and may also be subjected to known anchor coating treatments, printing, decoration, etc. However, since it is common to use resins other than polyolefins such as polyurethane and polyester for the anchor coating, it is preferable from the viewpoint of monomaterials not to perform anchor coating treatment.

[0031] [Coating layer] In this invention, a coating layer is provided for the purpose of improving the gas barrier performance and adhesion of the base film. However, in this invention, it is necessary to design with consideration to the fact that providing a coating layer increases costs due to the increased number of processes, and that it may impose an environmental burden, such as making recycling difficult depending on the film thickness.

[0032] The amount of coating layer attached is 0.10 to 0.50 (g / m²). 2) is preferred. When a coating layer using a polyvinyl alcohol-based copolymer and an inorganic layered compound described later is used for the above-mentioned polypropylene-based resin substrate, the inventors have found that by setting the adhesion amount within the above specific range, it is possible to achieve all of gas barrier properties, coat appearance, adhesion, and recyclability. As a result, the coating layer can be uniformly controlled during coating, resulting in a film with less coating unevenness and defects. In addition, since the coating layer is thin, it can contribute to reducing foreign matters during recycling. The adhesion amount of the coating layer preferably has a lower limit of 0.15 (g / m 2 ) or more, more preferably 0.20 (g / m 2 ) or more, still more preferably 0.25 (g / m 2 ) or more, and an upper limit preferably of 0.45 (g / m 2 ) or less, more preferably 0.40 (g / m 2 ) or less, still more preferably 0.35 (g / m 2 ) or less. When the adhesion amount of the coating layer exceeds 0.50 (g / m 2 ), the gas barrier property improves, but the cohesive force inside the coating layer becomes insufficient, and the uniformity of the coating layer also decreases. As a result, unevenness (increase in haze, whitening) and defects may occur in the coating appearance, or the gas barrier property and adhesion may not be fully exhibited. Also, in terms of processability, there is a risk of blocking due to the thick film thickness. Furthermore, there is a concern that it may have an adverse effect on the recyclability of the film. On the other hand, when the film thickness of the coating layer is less than 0.10 (g / m 2 ), there is a possibility that sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0033] A polyvinyl alcohol polymer is preferred as the resin composition used for the coating layer formed on the surface of the laminated film of the present invention. Polyvinyl alcohol polymers mainly consist of vinyl alcohol units, and a significant improvement in barrier performance can be expected due to their high cohesiveness based on hydrogen bonding structures. The degree of polymerization and degree of saponification of the polyvinyl alcohol polymer are determined based on the desired gas barrier properties and the viscosity of the coating aqueous solution. Regarding the degree of polymerization, a value of 2600 or less is preferred for ease of coating, as high aqueous solution viscosity and a tendency to gel make coating difficult. Regarding the degree of saponification, if it is less than 90%, sufficient oxygen gas barrier properties cannot be obtained under high humidity, and if it exceeds 99.7%, it is difficult to prepare the aqueous solution, and it is prone to gelation, making it unsuitable for industrial production. Therefore, a degree of saponification of 90 to 99.7% is preferred, and more preferably 93 to 99%. Furthermore, in the present invention, various copolymerized or modified polyvinyl alcohol polymers, such as polyvinyl alcohol polymers copolymerized with ethylene and polyvinyl alcohol polymers modified with silanol, can also be used, as long as they do not impair processability or productivity.

[0034] The coating layer of the present invention contains an inorganic layered compound. The presence of the inorganic layered compound is expected to create a labyrinthine effect on gases, thereby improving gas barrier properties. Examples of materials include clay minerals such as smectite, kaolin, mica, hydrotalcite, and chlorite (including their synthetic counterparts). Specifically, examples include montmorillonite, beiderite, saponite, hectorite, souconite, stevensite, kaolinite, nacrite, dickite, halloysite, hydrated halloysite, tetrasilicic mica, sodium teniolite, muscovite, margalite, phlogopite, talc, antigorite, chrysotile, pyrophyllite, vermiculite, xanthophyllite, and chlorite. Furthermore, flake silica and the like can also be used as inorganic layered compounds. These may be used individually or in combination of two or more. Among these, smectite (including its synthetic counterparts) is particularly preferred due to its high effect in improving water vapor barrier properties.

[0035] Furthermore, as the inorganic layered compound, it is preferable that it contains redox metal ions, particularly iron ions. Among such compounds, montmorillonite, a type of smectite, is preferred in terms of coating suitability and gas barrier properties. As the montmorillonite, known types that have been conventionally used as gas barrier agents can be used. For example, the following general formula: (X,Y)2~3Z4O10(OH)2·mH2O·(Wω) (In the formula, X represents Al, Fe(III), or Cr(III). Y represents Mg, Fe(II), Mn(II), Ni, Zn, or Li. Z represents Si or Al. W represents K, Na, or Ca. H2O represents intercalated water. m and ω represent positive real numbers.) Among these, the one in which W in the formula is Na is preferred because it cleaves in an aqueous medium.

[0036] The size and shape of the inorganic layered compound are not particularly limited, but the particle size (longest diameter) is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. If the particle size is larger than 5 μm, the dispersibility will be poor, which may result in deterioration of the coating properties and appearance of the coating layer. On the other hand, the aspect ratio is 50 to 5000, more preferably 100 to 4000, and even more preferably 200 to 3000.

[0037] The blending ratio of the polyvinyl alcohol copolymer to the inorganic layered compound in the coating layer of the present invention is preferably 75 / 25~35 / 65 (wt%), more preferably 70 / 30~40 / 60 (wt%), and even more preferably 65 / 35~45 / 55 (wt%). If the blending ratio of the inorganic layered compound is less than 25%, the barrier performance may be insufficient. On the other hand, if it is more than 65%, dispersibility will be poor, which may lead to deterioration of coating properties and adhesion.

[0038] In this invention, the ratio (P1 / P2) of the peak intensity with an absorption maximum in the region of 1040±10cm-1 (P1) to the peak intensity with an absorption maximum in the region of 3300±10cm-1 (P2) in the total reflection infrared absorption spectrum of the coating layer must be within the range of 3.0 to 25.0. Preferably, it is in the range of 4.0 to 24.0, and more preferably, in the range of 5.0 to 23.0. The peak at 1040±10cm-1 is a peak derived from the silica molecular structure and serves as an indicator of the amount of silica bonding derived from the inorganic layered compound in the coating layer. The peak at 3300±10cm-1 is a peak derived from hydroxyl groups and serves as an indicator of the amount of hydroxyl groups in the coating layer. (P1 / P2) represents the ratio of silica bonding to hydroxyl groups, and when this ratio is within the above range, silica particles are arranged in the film without inhibiting the hydrogen bonding of hydroxyl groups, and as a result, the gas barrier performance is maximized. Adhesion can also be achieved simultaneously. If (P1 / P2) is less than 3.0, the amount of silica bonding in the coating layer is low, and the labyrinth effect cannot be obtained, making it difficult to obtain satisfactory gas barrier properties. In addition, the coating layer may become more prone to blocking in terms of processability. On the other hand, if (P1 / P2) exceeds 25.0, the gas barrier properties improve, but the film becomes brittle, which is disadvantageous in terms of adhesion when used as a laminate. Furthermore, the dispersibility of the coating liquid deteriorates, raising concerns about poor appearance during coating (haze increase, whitening). In order to set the (P1 / P2) value of the coating layer within the predetermined numerical range described above, it is necessary to use the aforementioned materials, achieve the aforementioned predetermined adhesion amount, and furthermore, set the material mixing ratio within the aforementioned appropriate range, and combine it with the drying and heat treatment conditions described later.

[0039] In this invention, it is preferable that the arithmetic mean roughness of the coating layer in a 2 μm square field of view using an atomic force microscope is 2.0 to 8.0 nm. This maintains the uniformity of the coating layer and enables the expression of stable barrier performance, while the formation of surface irregularities mainly derived from the coordination of inorganic layered particles can improve adhesion and blocking resistance. The arithmetic mean roughness is preferably 2.5 nm or more, more preferably 3.0 nm or more, even more preferably 3.5 nm or more, preferably 7.5 nm or less, even more preferably 7.0 nm or less, and even more preferably 6.5 nm or less. If the arithmetic mean roughness exceeds 8.0 nm, the surface becomes too rough and the uniformity of the coating layer decreases, which may result in unevenness and defects in the appearance of the coating, leading to a decrease in printability, adhesion, and barrier properties. On the other hand, if the arithmetic mean roughness is less than 2.0 nm, the surface is too flat, which may reduce adhesion and ink transfer properties during printing. Furthermore, the blocking resistance, which will be described later, will also deteriorate, and blocking may occur when the film is wound into a roll. In order to obtain the arithmetic mean roughness value within the predetermined numerical range, it is necessary to use the aforementioned materials, achieve the predetermined adhesion amount, and further set the material mixing ratio within the aforementioned appropriate range, in combination with the dilution conditions of the coating solution and the drying and heat treatment conditions described later.

[0040] In this invention, it is preferable that the heat shrinkage rate of the laminated film at 150°C for 5 minutes is 10% or less in both the MD direction and the TD direction. This stabilizes the dimensional change of the substrate and can further improve the quality during printing and lamination. The heat shrinkage rate at 150°C for 5 minutes is preferably 8% or less, more preferably 7% or less, with a lower limit of 0%. If the heat shrinkage rate at 150°C for 5 minutes exceeds 10%, heat wrinkles and sagging are more likely to occur during processing, which may reduce the quality of the printed or laminated surface. Furthermore, the heat shrinkage rate at 120°C for 5 minutes is preferably 0.8% or less, more preferably 0.7% or less, with a lower limit of -0.8%. If the heat shrinkage rate at 120°C for 5 minutes exceeds 1%, heat wrinkles and sagging are more likely to occur during processing, which may reduce the quality of the printed or laminated surface.

[0041] The coating layer of the present invention may contain various crosslinking agents to improve the cohesive strength of the film and its resistance to moisture and heat adhesion, provided that these agents do not impair gas barrier properties or productivity. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, and isocyanate compounds. Among these, silicon-based crosslinking agents are particularly preferred from the viewpoint of improving water-resistant adhesion to the inorganic thin film layer. Other crosslinking agents such as oxazoline compounds, carbodiimide compounds, and epoxy compounds may also be used in combination. However, if recyclability is a priority, it is preferable not to include any crosslinking agents.

[0042] In this invention, the film haze after lamination of the coating layer is preferably 20% or less, more preferably 18% or less, and even more preferably 16% or less, from the viewpoint of the visibility of the contents. If the haze is greater than 20%, in addition to a significant deterioration in transparency, there is a concern that it will also affect the surface irregularities, which may lead to poor appearance in subsequent printing processes, etc. The haze can be adjusted by the composition ratio of the coating layer, solvent conditions, film thickness, etc. Here, the haze was evaluated in accordance with JIS K7136, using a turbidimeter (NDH2000, manufactured by Nippon Denshoku).

[0043] The coating method for the resin composition for the coating layer is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0044] When forming the coating layer, it is preferable to apply the resin composition for the coating layer, pre-dry it at a relatively low temperature to first evaporate the solvent, and then perform the main drying at a high temperature, as this will result in a uniform film. The pre-drying temperature is preferably 80 to 110°C, more preferably 85 to 105°C, and even more preferably 90 to 100°C. If the pre-drying temperature is below 80°C, the coating layer may not dry completely. If the pre-drying temperature is above 110°C, drying may proceed before the coating layer has a chance to spread evenly, potentially resulting in a poor appearance.

[0045] On the other hand, the drying temperature is preferably 110 to 140°C, more preferably 115 to 135°C, and even more preferably 120 to 130°C. If the drying temperature is below 110°C, the formation of the coating layer will not proceed, reducing cohesiveness and adhesion, which may negatively affect the barrier properties. If the temperature exceeds 140°C, the film may be subjected to too much heat, making it brittle or causing large wrinkles due to thermal shrinkage.

[0046] The preferred drying time for pre-drying is 3.0 to 10.0 seconds, more preferably 3.5 to 9.5 seconds, and even more preferably 4.0 to 9.0 seconds. Similarly, the preferred drying time for the main drying is 3.0 to 10.0 seconds, more preferably 3.5 to 9.5 seconds, and even more preferably 4.0 to 9.0 seconds. However, it is important to note that the drying conditions may vary depending on the type of heat transfer medium and the intake and exhaust conditions of the drying oven. In addition to drying, applying an additional heat treatment for 1 to 4 days at the lowest possible temperature range, specifically 40 to 60°C, is also more effective in promoting the formation of the coating layer.

[0047] [Packaging materials] When the laminated film of the present invention is used as a packaging material, it is preferable to form a laminate with a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the coating layer, but it may also be provided on the outside of the base film layer (the side opposite the surface where the coating layer is formed). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. As the thermoplastic polymer that forms the heat-sealable resin layer, any polymer that can exhibit sufficient sealant adhesion is acceptable, but polyethylene resins such as olefin-based HDPE, LDPE, LLDPE, polypropylene resin, ethylene-vinyl acetate copolymer, ethylene-α-olefin random copolymer, ionomer resin, etc. can be used. Among these, LLDPE or polypropylene resin is particularly preferred because it is highly versatile from the viewpoint of durability, seal strength, cost, and monomaterialization. The thickness of the sealant layer is preferably 20 to 100 μm, more preferably 30 to 90 μm, and more preferably 40 to 80 μm. If the thickness is thinner than 20 μm, sufficient seal strength may not be obtained, and it may be difficult to handle due to a lack of stiffness. On the other hand, if the thickness exceeds 100 μm, the material becomes too stiff, reducing its handling properties as a bag, and the price may also increase.

[0048] [Adhesive layer] The adhesive layer used in this invention can be any general-purpose laminating adhesive. For example, solvent-free, water-based, or heat-melt adhesives mainly composed of poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, or casein can be used. Among these, urethane or polyester adhesives are preferred considering heat resistance and flexibility to follow dimensional changes of each substrate. The adhesive layer can be applied by methods such as direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fontein coating, or other methods, and the coating amount after drying is 1 to 8 g / m² to achieve sufficient adhesion. 2 Preferably, 2-7 g / m². 2 More preferably 3-6 g / m 2 The coating amount is 1 g / m². 2 If the amount is less than 8 g / m², it becomes difficult to bond the entire surface, and the adhesive strength decreases. 2 Beyond this point, complete curing of the film takes longer, unreacted material is more likely to remain, and the adhesive strength decreases.

[0049] Furthermore, the laminated film of the present invention may have at least one printed layer or other plastic substrate and / or paper substrate laminated between or outside the base film layer and the heat-sealable resin layer.

[0050] Water-based and solvent-based resin-containing printing inks are preferably used as the printing ink for forming the printed layer. Examples of resins used in the printing ink include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoaming agents, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printed layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying, and infrared drying can be used.

[0051] The laminate of the present invention has an oxygen permeability of 50 ml / m² under conditions of 23°C × 65% RH. 2 A pressure of d·MPa or less is preferable for exhibiting good gas barrier properties. Furthermore, by controlling the aforementioned coating layer components and adhesion amount, a pressure of 40 ml / m² is preferable. 2 • d·MPa or less, more preferably 30 ml / m³ 2 It can be set to d·MPa or less. Oxygen permeability of 50 ml / m³ 2 Above d·MPa, it becomes difficult to meet the requirements for applications demanding high gas barrier properties. On the other hand, if the oxygen permeability is 1 ml / m³ in all cases... 2 If the oxygen permeability is less than d·MPa, although the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, and the amount transferred to the contents may increase relatively, which is undesirable. The preferred lower limit for oxygen permeability is 1 ml / m³. 2 It is d·MPa or higher.

[0052] The laminates of the present invention all exhibit a water vapor transmission rate of 4.0 g / m² under 40°C × 90% RH conditions. 2 A value of d or less is preferable in terms of exhibiting good gas barrier properties. Furthermore, by controlling the amount of the coating layer components mentioned above, a value of 3.5 g / m is preferable. 2 • d or less, more preferably 3.0 g / m 2It can be less than or equal to d. Water vapor transmission rate of 4.0 g / m³ 2 If the value exceeds d, it becomes difficult to meet the requirements for applications that demand high gas barrier properties. On the other hand, if the water vapor transmission rate is 0.1 g / m³ in all cases, it becomes difficult to meet the requirements for applications that require high gas barrier properties. 2 If the value is less than 0.1 g / m³, while the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, which may relatively increase the amount transferred to the contents, so this is undesirable. The preferred lower limit for water vapor permeability is 0.1 g / m³. 2 It is d or higher.

[0053] The laminates of the present invention preferably have a laminate strength of 1.0 N / 15 mm or more under 23°C × 65% RH conditions, more preferably 1.5 N / 15 mm or more, and even more preferably 2.0 N / 15 mm or more. If the laminate strength is less than 1.0 N / 15 mm, delamination may occur due to bending load or heat during sealing, potentially degrading the barrier properties or causing leakage of contents. Furthermore, the tearability may also deteriorate. [Examples]

[0054] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. The films were evaluated by the following measurement method.

[0055] (1) Thickness of the laminated film Measurements were taken using a dial gauge in accordance with JIS K7130-1999 Method A.

[0056] (2) Haze of laminated film Measurements were taken using a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

[0057] (3) Amount of coating layer In each example and comparative example, the laminated film obtained at the stage of laminating the coating layer onto the base film was used as a sample. A 100 mm x 100 mm test piece was cut from this sample, the coating layer was wiped off with ethanol, and the amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0058] (4) Method for measuring the total internal reflection infrared absorption spectrum of laminated films In each example and comparative example, the total internal reflection infrared absorption spectrum was measured on the surface of the coating layer of each laminated film obtained at the stage when the coating layer was laminated on the base film, and the peak intensity (P1) with an absorption maximum in the region of 1040 ± 10 cm⁻¹ and the peak intensity (P2) with an absorption maximum in the region of 3000 ± 10 cm⁻¹ were determined, and the intensity ratio (P1 / P2) was calculated. Each peak intensity was calculated from the peak height drawn by vertically connecting the baseline with zero absorbance and each peak top.

[0059] (5) Method for measuring the arithmetic mean roughness of the coating layer The surface roughness of the laminated film was measured using a scanning probe microscope (SPM) (Shimadzu Corporation "SPM9700") (cantilever: OMCL-AC200TS provided by Olympus Corporation, observation mode: phase mode). Specifically, SPM images were obtained over a 2 μm square field of view of the film surface. Using the tilt correction function of the SPM software, tilt correction was performed in the X, Y, and Z directions on the obtained images, and then the arithmetic mean roughness value was calculated. The arithmetic mean roughness was calculated by taking a reference length from the roughness curve obtained by removing surface waviness components longer than a predetermined wavelength from the cross-sectional curve using a high-pass filter, taking the X axis in the direction of the mean line and the Y axis in the direction of the vertical magnification, and representing the roughness curve as y=f(X), and extending the value obtained by the following formula into two dimensions. Ra = 1 / L∫L0 |f(x)|dx L: reference length

[0060] (6) Method for evaluating oxygen permeability In each example and comparative example, the laminated film obtained at the stage of laminating a coating layer onto a base film was used as a sample, and the oxygen permeability was measured in accordance with JIS-K7126 B method using an oxygen permeability measuring device (MOCON "OX-TRAN(registered trademark) 1 / 50") under an atmosphere of 23°C and 65% RH humidity. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side to the coating layer side.

[0061] (7) Method for evaluating water vapor transmission In each example and comparative example, the laminated films obtained at the stage of laminating a coating layer onto a base film were used as samples, and the water vapor transmission rate was measured in accordance with JIS-K7129 B method using a water vapor transmission rate measuring device (MOCON "PERMATRAN-W 3 / 33MG") under an atmosphere of 40°C and 90% RH humidity. The water vapor transmission rate was measured in the direction in which water vapor permeated from the base film side to the coating layer side.

[0062] (8) Evaluation of the blocking resistance of laminated films In each example and comparative example, each laminated film obtained at the stage of laminating a coating layer on a base film was used as a sample. Two sets of samples were prepared, cut into strips 15 mm wide and 200 mm long. One drop of water (approximately 0.02 g) was dropped onto the coating layer surface of one sample, then the coating layer surface of the other sample was placed on top, sandwiched between glass plates, and dried at 40°C for 24 hours to evaporate the moisture. After that, the two strips were peeled apart and the adhesion of the film was checked. Samples that were so adhered that the film tore when peeled apart were judged as ×, and samples that could be peeled apart smoothly without tearing were judged as ○.

[0063] (9) Evaluation of solvent volatility of the coating layer In each example and comparative example, the laminated film obtained at the stage of laminating the coating layer onto the base film was used as a sample. When the coating layer was lightly pressed with a paper towel, those in which the coating layer adhered to the paper towel were judged as having insufficient solvent evaporation (×), and those in which the coating layer did not adhere to the paper towel were judged as having sufficient solvent evaporation (○).

[0064] (10) Appearance evaluation of the coating layer In each example and comparative example, the laminated film obtained at the stage of laminating the coating layer onto the base film was used as a sample. Those with visible defects such as gaps, streaks, or unevenness in the coating layer were judged as having a poor appearance (×), while those without such defects were judged as having a good appearance (○).

[0065] (11) Evaluation of shrinkage rate by heating at 150℃ for 5 minutes In each example and comparative example, a test specimen with a width of 20 mm and a length of 300 mm is prepared so that the measurement direction (MD or TD) of the prepared film is the longer side, and gauge marks are made at a distance of 200 mm from the center of the test specimen. Then, the distance between the gauge marks is read to one decimal place using a metal ruler to determine the gauge mark distance A before heating. Next, the end of this test specimen is clipped and suspended from a metal bar, and placed in a heating oven heated to 150°C ± 1°C for 5 minutes. After heating, the gauge mark distance of the removed test specimen is read using a metal ruler in the same way as before heating to determine the gauge mark distance B after heating. Based on the obtained values, the heat shrinkage rate is calculated using the following formula. Heat shrinkage rate (%) = (AB) / A × 100 (12) Evaluation of shrinkage rate by heating at 120℃ for 5 minutes In each example and comparative example, a test specimen with a width of 20 mm and a length of 300 mm is prepared so that the measurement direction (MD or TD) of the prepared film is the longer side, and gauge marks are made at a distance of 200 mm from the center of the test specimen. Then, the distance between the gauge marks is read to one decimal place using a metal ruler to determine the gauge mark distance A before heating. Next, the end of this test specimen is clipped and suspended from a metal bar, and placed in a heating oven heated to 120°C ± 1°C for 5 minutes. After heating, the gauge mark distance of the removed test specimen is read using a metal ruler in the same way as before heating to determine the gauge mark distance B after heating. Based on the obtained values, the heat shrinkage rate is calculated using the following formula. Heat shrinkage rate (%) = (AB) / A × 100

[0066] [Production of printed materials] On top of the laminates obtained in the examples and comparative examples, white ink (NEWLP Super R631AD White N, manufactured by Toyo Ink Co., Ltd.) was applied and dried at a maximum drying temperature of 120°C. The ink layer after this drying process was 0.1 g / m². 2 After coating the material, the printed materials were stored at 40°C for one day to obtain the respective printed products. (13) Evaluation of finish quality during printing The printed materials produced as described above were visually inspected. Those with noticeable wrinkles or sagging on the substrate were judged as having poor finish quality (marked with an "X"), while those without such issues were judged as having good finish quality (marked with an "O").

[0067] [Fabrication of laminated structures] A polyurethane adhesive (Takelac A525S / Takenate A50, manufactured by Mitsui Chemicals, Inc.) was applied to the laminates obtained in the Examples and Comparative Examples so that the thickness after drying at a maximum drying temperature of 120°C was 3 μm. Then, an unstretched polypropylene film (Toyobo P1128; thickness 30 μm; referred to as CPP) was dry-laminated on a metal roll heated to 60°C, and aged at 40°C for 4 days to obtain a laminate gas barrier laminate for evaluation (hereinafter sometimes referred to as "laminated laminate a").

[0068] (14) Method for evaluating laminate strength The laminated material prepared as described above was cut into 15 mm wide and 200 mm long specimens to form test pieces. The laminate strength (normal state) was measured using a Tensilon universal material tester (Tensilon UMT-II-500 model, manufactured by Toyo Baldwin Co., Ltd.) under conditions of 23°C and 65% relative humidity. The laminate strength was measured when the laminated film layer and the heat-sealable resin layer of each laminated film obtained in the examples and comparative examples were peeled at a peeling angle of 90 degrees with a tensile speed of 200 mm / min. (15) Evaluation of finish quality during dry lamination The laminated structures prepared as described above were visually inspected. Those with noticeable wrinkles or sagging on the base material were judged as having poor finish quality (marked with ×), while those without such issues were judged as having good finish quality (marked with ○).

[0069] [Creation of bag products] Using the laminated material prepared above, an A4-sized cut sheet was created. This cut sheet was folded in half so that the CPP sides faced each other, and the four sides were pressure-sealed and heat-sealed using a Seibu Machinery Co., Ltd. test sealer "Type TYB-300" under the following sealing conditions to create a bag. Sealing conditions (seal bar width: 10 mm, seal bar: heating temperature) (60±1℃, seal bar pressure: 0.2MPa, sealing time: 2 seconds, cooling time: 1 second) (16) Evaluation of finish quality during bag making and sealing The area near the seal of the bags produced as described above was visually inspected. Bags with noticeable wrinkles or sagging in the base material were judged as having poor finish quality (×), while those without such issues were judged as having good finish quality (○).

[0070] The details of the coating solutions used in this example and comparative example are described below. These were used in Examples 1-6 and Comparative Examples 1-10, and are shown in Table 1.

[0071] [Polyvinyl alcohol resin (A)] 90 parts by mass of purified water were mixed with 10 parts by mass of fully saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: G Polymer OKS8049Q, (saponification degree 99.0% or higher, average degree of polymerization 450)). The mixture was heated to 80°C while stirring, and then stirred for approximately 1 hour. After that, it was cooled to room temperature to obtain a nearly transparent polyvinyl alcohol solution (PVA solution) with a solid content of 10%.

[0072] [Inorganic layered compound dispersion (B)] Five parts by mass of montmorillonite (trade name: Kunipia F, manufactured by Kunimine Industries Co., Ltd.), an inorganic layered compound, were added to 95 parts by mass of purified water while stirring, and thoroughly dispersed using a homogenizer at a setting of 1500 rpm. The mixture was then incubated at 23°C for one day to obtain a dispersion of the inorganic layered compound with a solid content of 5%.

[0073] [Coating liquid 1 to be used for the coating layer] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 20.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 35.00% by mass Inorganic layered compound dispersion (B) 30.00% by mass

[0074] [Coating liquid used for the coating layer 2] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 15.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 30.00% by mass Inorganic layered compound dispersion (B) 40.00% by mass

[0075] [Coating liquid 3 for use in the coating layer] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 10.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 25.00% by mass Inorganic layered compound dispersion (B) 50.00% by mass

[0076] [Coating liquid used for the coating layer 4] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 5.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 20.00% by mass Inorganic layered compound dispersion (B) 60.00% by mass

[0077] [Coating liquid used for the coating layer 5] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 35.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 50.00% by mass

[0078] [Coating liquid used for the coating layer 6] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Ion-exchanged water 30.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 45.00% by mass Inorganic layered compound dispersion (B) 10.00% by mass

[0079] [Coating liquid used for the coating layer 7] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the coating layer). Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 15.00% by mass Inorganic layered compound dispersion (B) 70.00% by mass

[0080] [Coating liquid used for the coating layer 8] The following materials were mixed in the mass ratio shown below and stirred for at least 30 minutes to dissolve. Then, undissolved material was removed using a filter with a nominal filtration accuracy of 50 μm to prepare a coating solution (resin composition for the coating layer). Ion-exchanged water 37.50% by mass Polyvinylidene chloride resin (C) 62.50% by mass (Saran latex L557 manufactured by Asahi Kasei Chemicals, solids content ratio 48%)

[0081] (Coating the film with a coating solution (lamination of coating layers)) The coating solution prepared above was applied to the corona-treated surface of the substrate film by gravure roll coating, pre-dried at 90°C for 4 seconds, and then fully dried at 130°C for 4 seconds to obtain a coating layer. The coating amount after drying was 0.25 g / m². 2 The sample was (Dry). Subsequently, a post-heat treatment was performed at 40°C for 2 days. The coating liquid constituting the coating layer, as well as the temperature of the main drying and the post-heat treatment conditions, were changed for each example and comparative example as shown in Table 1.

[0082] As described above, laminated films with a coating layer on a base film were prepared. For the base film, Examples 1-6, Comparative Examples 1-6, and 8-10 used Toyobo Co., Ltd.'s Pylen Film High Heat Resistance / High Rigidity Type P2171, without antistatic agent, with a thickness of 20 μm. Comparative Example 7 used Toyobo Co., Ltd.'s Ester Film E5100, with a thickness of 12 μm. Comparative Example 11 used Toyobo Co., Ltd.'s Pylen Film P2102, with a thickness of 20 μm. The resulting laminated films were evaluated. The results are shown in Table 1.

[0083] [Table 1A]

[0084] [Table 1B]

[0085] [Table 1C]

[0086] [Table 1D] [Industrial applicability]

[0087] According to the present invention, it is possible to provide a laminated film that can form a laminate structure composed of almost a single resin type, mainly polypropylene film, which has a low environmental impact, and that has the necessary gas barrier properties and adhesive properties required for packaging materials. Moreover, since the laminated film of the present invention has few processing steps and excellent processability and can be easily manufactured, it is excellent in both economy and production stability, and can provide a gas barrier film with homogeneous properties.

Claims

1. A laminated film comprising a base film and a coating layer having a polyvinyl alcohol copolymer and an inorganic layered compound on at least one side thereof, wherein the laminated film satisfies the following requirements (a) to (f). (a) The base film is a stretched film made of a propylene resin. (b) The amount of the coating layer attached is 0.10 g / m ２ 0.50g / m or more ２ The following conditions must be met: (c) In the total reflection infrared absorption spectrum of the laminated film, 1040 ± 10 cm⁻¹ －１ The peak intensity (P1) has an absorption maximum in the region and is 3300 ± 10 cm. －１ The ratio (P1 / P2) of peak intensities (P2) with absorption maxima in the specified region is within the range of 3.0 to 25.

0. (d) The heat shrinkage rate of the laminated film at 150°C for 5 minutes is 8% or less in both the MD direction and the TD direction. (e) The arithmetic mean roughness of the coating layer on the laminated film in a 2 μm square area is in the range of 2.0 to 8.0 nm. (f) The oxygen permeability of the laminated film under a 23°C × 65% RH environment is 50 ml / m². ２ - Water vapor transmission rate of 4 g / m³ under conditions of d MPa or less and 40°C × 90% RH ２ - It must be less than or equal to d.

2. The laminated film according to claim 1, characterized in that the heat shrinkage rate of the laminated film at 120°C for 5 minutes is 1% or less in both the MD direction and the TD direction.

3. The laminated film according to claim 1 or 2, characterized in that the inorganic layered compound of the coating layer contains a montmorillonite-based compound as a constituent component.

4. A packaging material comprising a laminated film according to any one of claims 1 to 3, with an olefin-based sealant layer laminated on one side.

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