Laminated film and packaging material

Abstract

[Problem] The present invention addresses the problem of providing a laminated film that is a film capable of forming a laminated structure mainly comprising a polypropylene film and containing almost a single type of resin having little environmental impact, and that has adhesiveness and gas barrier properties required for packaging materials and necessary properties such as processing suitability. [Solution] A laminated film in which a coating layer having a polyvinyl alcohol-based copolymer and an inorganic layered compound is provided on at least one surface of a base film, and characterized by satisfying requirements (a) to (d). (a) The base film is a stretched film using a propylene-based resin. (b) The attached amount of the coating layer is 0.10-0.50 g / m2.<sp / > (c) In a total reflection infrared absorption spectrum of the laminated film, the ratio (P1 / P2) of a peak intensity (P1) having an absorption maximum in a region of 1040±10 cm-1 to a peak intensity (P2) having an absorption maximum in a region of 3300±10 cm-1 is within the range of 3.0-25.0. (d) The heat shrinkage rate of the laminated film at 150°C × 5 min is at most 10% both in the MD direction and in the TD direction.

Description

Technical Field

[0001] The present invention relates to a gas barrier laminated film. More specifically, the present invention relates to a gas barrier coated film that has less environmental impact during manufacturing and disposal, excellent gas barrier performance, sufficient adhesive strength as a packaging material, and dimensional stability during secondary processing.

Background Art

[0002] In recent years, regulations for reducing the use of disposable plastics have been strengthened in various countries around the world, including in Europe. This is due to the increasing international awareness of resource recycling and the worsening waste problems in emerging countries. Therefore, plastic packaging materials required for foods, pharmaceuticals, etc. are also required to be environmentally friendly products from the perspective of 3R (recycle, reuse, reduce).

[0003] The performances required for the above-mentioned environmentally friendly packaging materials include (1) being made of recyclable materials, (2) having gas barrier performance capable of blocking various gases and extending the shelf life, (3) having a laminate structure with less environmental impact (for example, not using organic solvents, using less material itself, and being recyclable by monomaterialization), etc.

[0004] In recent years, in order to enable the above (2) and (3), attention has been focused on the use of polypropylene films. Polypropylene films are widely used in a wide range of applications such as packaging for foods and various products, electrical insulation, and surface protection films. Polypropylene films can exhibit high water vapor barrier properties due to their molecular structure. Furthermore, since polypropylene-based or polyethylene-based heat seal resins are generally used as sealants for laminating with the surface base film, for example, by using a polypropylene film for the surface base material and an unstretched polypropylene sheet for the sealant, it is possible to achieve monomaterialization of the entire packaging material while having gas barrier properties, and an environmentally friendly packaging material design that is easy to recycle can be achieved.

[0005] However, with respect to the gas barrier property of (2) above, although the polypropylene film has a water vapor barrier property, it is not a sufficient value compared to, for example, a transparent inorganic vapor-deposited polyester film that is generally considered to have excellent water vapor barrier property. Also, with respect to the oxygen barrier property, there was a problem that it was very poor. In contrast, a film obtained by laminating a polymer resin composition such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride resin, or polyacrylonitrile, which is generally said to have a relatively high oxygen barrier property, to the polypropylene film has been used (for example, see Patent Documents 1 to 3).

[0006] However, the gas barrier coated film using the above polymer resin composition of polyvinyl alcohol or ethylene-vinyl alcohol copolymer has a large humidity dependence, and thus a decrease in gas barrier property was observed under high humidity. Also, polyvinylidene chloride resin and polyacrylonitrile have low humidity dependence, but have a problem that the barrier value as an absolute value is insufficient, and further, there is a high risk of generating harmful substances during disposal and incineration.

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

[0008] However, these gas barrier coated films require sufficient heat treatment for crosslinking. When the base material is a polypropylene film, it cannot satisfy sufficient properties as a packaging material due to deterioration of mechanical properties and heat distortion during processing. Also, during the heat treatment during processing, a large amount of heat energy is required, so it is not preferable from the viewpoint of environmental load. Furthermore, the 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 detour effect of gas molecules, showing good gas barrier properties (see, for example, Patent Documents 6 and 7).

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

[0011] In order to exhibit sufficient barrier performance, all of the above-mentioned 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 with a single material. Furthermore, in processing steps such as printing, there are problems of coating unevenness and printing defects due to unevenness.

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, a design considering the environment has 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 sufficiently 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 has improvement in processability by thinning the coating layer and consideration for the environment 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 shelf life, 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 based on a polypropylene film, and a laminated film having necessary performances such as gas barrier property, adhesiveness, and further processability required for a packaging material. Further, 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 the present invention have significantly improved the gas barrier performance by laminating a predetermined coating layer that meets the required performance on a polypropylene film. Furthermore, they have found that it is possible to provide a film with low environmental impact, reduced wrinkles and creases in secondary processing such as printing and lamination, and high quality, thus completing the present invention.

[0016] That is, the present invention is composed of the following configurations. 1. A laminated film provided with a coating layer having a polyvinyl alcohol copolymer and an inorganic layered compound on at least one side of a base film, wherein the laminated film satisfies the following requirements (a) to (d). A laminated film characterized by this. (a) The base film is a stretched film using a propylene copolymer. (b) The coating amount of the coating layer is 0.10 g / m 2 or more and 0.50 g / m 2 or less. (c) In the total reflection infrared absorption spectrum of the laminated film, the peak intensity (P1) having an absorption maximum in the region of 1040 ± 10 cm -1 and the peak intensity (P2) having an absorption maximum in the region of 3000 ± 10 cm -1 The ratio (P1 / P2) of the absorption maximum is in the range of 3.0 to 25.0. (d) The heat shrinkage rate of the laminated film at 150 ° C. × 5 minutes is 10% or less in both the MD direction and the TD direction. 2. The laminated film according to 1., wherein the arithmetic mean roughness in a 2 μm square of the coating layer on the laminated film is in the range of 2.0 to 8.0 nm. 3. The laminated film according to 1. or 2., wherein the heat shrinkage rate of the laminated film at 120 ° C. × 5 minutes is 1% or less in both the MD direction and the TD direction. 4. The oxygen permeability of the laminated film in an environment of 23 ° C. × 65% RH is 50 ml / m 2 ·d·MPa or less, and the water vapor permeability in an environment of 40 ° C. × 90% RH is 4 g / m 2The laminated film according to any one of 1. to 3., characterized in that it is ·d or less. 5. The laminated film according to any one of 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 obtained by laminating an olefin-based sealant layer on one side of the laminated film according to any one of 1. to 5.

Effect of the Invention

[0017] By such a technique, the present inventors have been able to provide a laminated film having necessary performances such as barrier properties, adhesiveness, and processability required for packaging materials while considering the environment.

Mode for Carrying Out the Invention

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

[0019] In addition, the biaxially stretched polypropylene resin film used in the present invention may be a single-layer film, or may be a laminated film in which a plurality of resin films including the biaxially stretched polypropylene resin film are laminated. The type, number of laminations, lamination method, etc. of the laminate in the case of a laminated film are not particularly limited, and can be arbitrarily selected from known methods according to the purpose.

[0020] In the present invention, as the polypropylene resin constituting the base film, a propylene homopolymer substantially free of comonomer is preferable. Even when a comonomer is included, the amount of the comonomer is preferably 0.5 mol% or less. The upper limit of the comonomer amount is more preferably 0.3 mol%, and even more preferably 0.1 mol%. When it is in the above range, the crystallinity is improved, the heat shrinkage rate at high temperature is reduced, and the heat resistance is improved. Note that a trace amount of comonomer may be included as long as the crystallinity is not significantly reduced.

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

[0022] The lower limit of the xylene-soluble content of the polypropylene resin constituting the base film is preferably 0.1% by mass from a practical aspect. The upper limit of the xylene-soluble content is preferably 7% by mass, more preferably 6% by mass, and even more preferably 5% by mass. When it is in the above range, the crystallinity is improved, the heat shrinkage rate at high temperature is further reduced, and the 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. The lower limit of the MFR is more preferably 1.0 g / 10 min, still more preferably 2.0 g / 10 min, particularly preferably 4.0 g / 10 min, and most preferably 6.0 g / 10 min. When within the above range, the mechanical load is small and extrusion and stretching become easy. The upper limit of the MFR is preferably 20 g / 10 min. The upper limit of the MFR is more preferably 17 g / 10 min, still more preferably 16 g / 10 min, and particularly preferably 15 g / 10 min. When within the above range, stretching becomes easy, thickness unevenness becomes small, the stretching temperature and heat setting temperature can be easily increased, the heat shrinkage rate becomes smaller, and the heat resistance is improved.

[0024] From the viewpoint of heat resistance, the base film may be a uniaxially stretched film in the longitudinal direction (MD direction) or the transverse direction (TD direction), but is preferably a biaxially stretched film. In the present invention, by stretching at least uniaxially, a film having a high heat resistance with a low heat shrinkage rate at a high temperature, which could not be expected in conventional polypropylene films, can be obtained. Examples of the stretching method include the simultaneous biaxial stretching method and the sequential biaxial stretching method. From the viewpoint of good flatness, dimensional stability, and thickness unevenness, the sequential biaxial stretching method is preferred.

[0025] In the sequential biaxial stretching method, the polypropylene resin is heated and melted by a single-screw or twin-screw extruder so that the resin temperature is 200°C or higher and 280°C or lower, formed into a sheet shape from a T-die, and extruded onto a chill roll at a temperature of 10°C or higher and 100°C or lower to obtain an unstretched sheet. Then, it can be roll-stretched 3.0 times or more and 8.0 times in the longitudinal direction (MD direction) at 120°C or higher and 165°C or lower, and subsequently, after preheating with a tenter, stretched 4.0 times or more and 20.0 times or less in the transverse direction (TD direction) at a temperature of 155°C or higher and 175°C or lower. Further, after biaxial stretching, a heat setting treatment can be performed while allowing a relaxation of 1% or more and 15% or less at a temperature of 165°C or higher and 175°C or lower.

[0026] In order to impart handling properties (for example, winding properties after lamination) to the base film used in the present invention, it is preferable to contain particles in the film to form protrusions on the film surface. Examples of the particles to be contained in 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-formalin condensate. From the viewpoint of transparency, the content of the particles in the film is preferably small, for example, preferably 1 ppm or more and 1000 ppm or less. Further, from the viewpoint of transparency, it is preferable to select particles having a refractive index close to that of the resin used. In addition, in order to impart various functions to the film as necessary, the film may contain an antioxidant, an ultraviolet absorber, an antistatic agent, a pigment, a lubricant, a nucleating agent, an adhesive, an antifogging agent, a flame retardant, an antiblocking agent, an inorganic or organic filler, and the like.

[0027] In addition to the polypropylene resin used in the present invention, within a range that does not impair the object of the present invention, for the purpose of improving the mechanical properties of the base film and the adhesiveness to an ink layer or an adhesive layer laminated on the gas barrier coat layer, etc., it may be contained in the film. For example, a random copolymer which is a polypropylene resin different from the above, a copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms, various elastomers, etc. are mentioned.

[0028] In the present invention, the thickness of the base film is arbitrarily set according to each application, but the lower limit is preferably 2 μm or more, more preferably 3 μm or more, still 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, still more preferably 200 μm or less, and particularly preferably 100 μm or less. When the thickness is thin, the handling properties tend to be poor. On the other hand, when the thickness is thick, there are not only problems in terms of cost, but also flatness defects due to winding marks are likely to occur when stored in a rolled state.

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

[0030] In addition, the base film layer in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, or surface roughening treatment as long as the object of the present invention is not impaired. Also, known anchor coat treatment, printing, decoration, etc. may be performed. However, since it is common to use resins other than polyolefins such as polyurethane and polyester for the anchor coat, it is preferably not subjected to anchor coat treatment from the viewpoint of single material.

[0031] [Coating layer] In the present invention, a coating layer is provided for the purpose of improving the gas barrier performance and adhesiveness of the base film. However, in the present invention, it is necessary to design while paying attention to the environmental load such as an increase in cost due to an increase in the number of steps by providing a coating layer and difficulty in recycling depending on the film thickness.

[0032] The coating amount of the coating layer is 0.10 to 0.50 (g / m 2) is preferably used. When a coating layer using a polyvinyl alcohol copolymer and an inorganic layered compound described later is used for the above-mentioned polypropylene resin base material, the inventors have found that all of gas barrier properties, coat appearance, adhesiveness, and recyclability can be achieved by setting the adhesion amount within the above specific range. 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 lower limit of the adhesion amount of the coating layer is preferably 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 the upper limit is preferably 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 is improved, 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 coat appearance, or the gas barrier property and adhesiveness may not be fully exhibited. In addition, in terms of processability, blocking may occur 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 ), sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0033] As the resin composition used for the coating layer formed on the surface of the laminated film of the present invention, a polyvinyl alcohol-based polymer is desirable. The polyvinyl alcohol-based polymer has vinyl alcohol units as the main constituent components, and a significant improvement in barrier performance due to high cohesiveness by a hydrogen bond structure can be expected. The degree of polymerization and the degree of saponification of the polyvinyl alcohol-based polymer are determined from the intended gas barrier property, the viscosity of the coating aqueous solution, and the like. Regarding the degree of polymerization, since the viscosity of the aqueous solution is high and it is likely to gel, coating becomes difficult, and it is preferably 2600 or less from the workability of coating. Regarding the degree of saponification, if it is less than 90%, sufficient oxygen gas barrier property under high humidity cannot be obtained, and if it exceeds 99.7%, adjustment of the aqueous solution is difficult, it is likely to gel, and it is not suitable for industrial production. Therefore, the degree of saponification is preferably 90 to 99.7%, more preferably 93 to 99%. Further, in the present invention, various copolymerized or modified polyvinyl alcohol-based polymers such as a polyvinyl alcohol-based polymer copolymerized with ethylene and a silanol-modified polyvinyl alcohol-based polymer can also be used as long as the processability and productivity are not impaired.

[0034] The coating layer of the present invention contains an inorganic layered compound. By the presence of the inorganic layered compound, a maze effect against gases can be expected, and the gas barrier property is improved. Examples of the material include clay minerals such as smectite, kaolin, mica, hydrotalcite, chlorite (including synthetic products thereof). Specifically, montmorillonite, beidellite, saponite, hectorite, sauconite, stevensite, kaolinite, nacrite, dickite, halloysite, hydrated halloysite, tetrasilicic mica, sodium teniolite, muscovite, margarite, phlogopite, talc, antigorite, chrysotile, pyrophyllite, vermiculite, zansorphyllite, chlorite, etc. can be mentioned. Furthermore, flaky silica etc. can also be used as the inorganic layered compound. These may be used alone or in combination of two or more. Among these, smectite (including synthetic products thereof) is particularly preferable because of its high effect of improving the water vapor barrier property.

[0035] As the inorganic layered compound, those having metal ions with redox properties, particularly iron ions, present therein are preferable. Further, among such compounds, montmorillonite, which is a type of smectite, is preferable from the viewpoints of coating applicability and gas barrier properties. As the montmorillonite, known ones 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 interlayer water. m and ω represent positive real numbers.) Among these, those in which W in the formula is Na are preferable from the viewpoint of exfoliating in an aqueous medium.

[0036] The size and shape of the inorganic layered compound are not particularly limited, but the particle size (major axis) 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 is poor, and as a result, the coating applicability and coat appearance of the coating layer may deteriorate. On the other hand, the aspect ratio thereof is 50 to 5000, more preferably 100 to 4000, and even more preferably 200 to 3000.

[0037] The mixing ratio of the polyvinyl alcohol-based copolymer and the inorganic layered compound in the coating layer of the present invention is preferably 75 / 25 to 35 / 65 (wt%), more preferably 70 / 30 to 40 / 60 (wt%), and even more preferably 65 / 35 to 45 / 55 (wt%). If the mixing ratio of the inorganic layered compound is less than 25%, the barrier performance may be insufficient. On the other hand, if it is more than 65%, the dispersibility may deteriorate, the coating applicability may deteriorate, or the adhesiveness may deteriorate.

[0038] In the present invention, the ratio (P1 / P2) of the peak intensity (P1) having an absorption maximum in the region of 1040 ± 10 cm-1 to the peak intensity (P2) having an absorption maximum in the region of 3300 ± 10 cm-1 in the total reflection infrared absorption spectrum of the coating layer needs to 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, it is in the range of 5.0 to 23.0. The peak at 1040 ± 10 cm-1 is a peak derived from the silica molecular structure and serves as an index indicating the amount of silica bonds derived from the inorganic layered compound in the coating layer. Also, the peak at 3300 ± 10 cm-1 is a peak derived from hydroxyl groups and serves as an index indicating the amount of hydroxyl groups in the coating layer. (P1 / P2) represents the ratio of silica bonds to hydroxyl groups. 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 maximally exhibited. Also, adhesion can be simultaneously exhibited. When (P1 / P2) is less than 3.0, the amount of silica bonds in the coating layer is small, and the maze effect cannot be obtained, so it may be difficult to obtain satisfactory gas barrier properties. Also, there is a possibility that the coating layer may be prone to blocking in terms of processability. On the other hand, when (P1 / P2) exceeds 25.0, the gas barrier property is improved, but the film becomes brittle, which is disadvantageous in terms of adhesion when forming a laminate laminate. In addition, the dispersibility of the coating liquid deteriorates, and there is a concern that appearance defects (haze increase, whitening) may occur during coating. In order to make the value of (P1 / P2) of the coating layer within the above-mentioned predetermined numerical range, it is necessary to use the above-mentioned materials to achieve the above-mentioned predetermined adhesion amount, further set the mixing ratio of the materials within the above-mentioned appropriate range, and combine with the drying and heat treatment conditions described below.

[0039] In the present invention, it is preferable that the arithmetic mean roughness of the coating layer in a field angle of 2 μm square using an atomic force microscope is 2.0 to 8.0 nm. Thereby, the uniformity of the coating layer can be maintained and stable barrier performance can be exhibited, and the adhesiveness and blocking resistance can be enhanced by forming surface irregularities mainly derived from the coordination of inorganic layered particles. The arithmetic mean roughness is preferably 2.5 nm or more, more preferably 3.0 nm or more, still more preferably 3.5 nm or more, and preferably 7.5 nm or less, more preferably 7.0 nm or less, still more preferably 6.5 nm or less. When the arithmetic mean roughness exceeds 8.0 nm, the surface becomes too rough and the uniformity of the coating layer also decreases, so that unevenness and defects may occur in the coat appearance, resulting in a decrease in printing suitability, adhesiveness, and barrier properties. On the other hand, when the arithmetic mean roughness is less than 2.0 nm, the surface is too flat, so that the adhesiveness and ink transferability during printing may decrease. In addition, the blocking resistance described later also deteriorates, and blocking may occur when the film is wound into a roll shape. In order to make the value of the arithmetic mean roughness fall within the above-mentioned predetermined numerical range, it is necessary to use the above-mentioned materials to obtain the above-mentioned predetermined adhesion amount, further make the blending ratio of the materials fall within the above-mentioned appropriate range, and combine with the dilution conditions, drying / heat treatment conditions of the coating liquid described later.

[0040] In the present 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. Thereby, the dimensional change of the base material is stabilized and the quality during printing processing and laminating processing can be further improved. The heat shrinkage rate at 150 °C for 5 minutes is preferably 8% or less, more preferably 7% or less, and the lower limit is preferably 0%. When the heat shrinkage rate at 150 °C for 5 minutes exceeds 10%, heat wrinkles and sagging are likely to occur during processing, so that the quality of the printing surface and the laminating surface may decrease. In addition, the heat shrinkage rate at 120 °C for 5 minutes is preferably 0.8% or less, more preferably 0.7% or less, and the lower limit is preferably -0.8%. When the heat shrinkage rate at 120 °C for 5 minutes exceeds 1%, heat wrinkles and sagging are likely to occur during processing, so that the quality of the printing surface and the laminating surface may decrease.

[0041] In the coating layer of the present invention, various crosslinking agents may be blended within a range that does not impair gas barrier properties and productivity for the purpose of improving the cohesion of the film and the adhesion resistance to heat and humidity. Examples of the crosslinking agent include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, isocyanate compounds, etc. Among them, the silicon-based crosslinking agent is particularly preferable from the viewpoint of improving the water-resistant adhesion to the inorganic thin film layer. In addition, an oxazoline compound, a carbodiimide compound, an epoxy compound, etc. may be used in combination as the crosslinking agent. However, when importance is attached to recyclability, it is preferable not to blend the crosslinking agent.

[0042] In the present invention, from the viewpoint of the visibility of the contents, the haze of the film after coating layer lamination is preferably 20% or less, more preferably 18% or less, and still more preferably 16% or less. When the haze is greater than 20%, in addition to a significant deterioration in transparency, there is also a concern of affecting the surface unevenness, which may lead to appearance defects in subsequent printing processes and the like. The haze can be adjusted by the composition ratio of the coating layer, solvent conditions, film thickness, etc. Here, the evaluation of the haze was based on JIS K7136, and a turbidimeter (manufactured by Nippon Denshoku, NDH2000) was used.

[0043] The coating method of 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, ordinary coating methods such as gravure coating, reverse roll coating, wire bar coating, die coating, etc. can be adopted.

[0044] When forming the coating layer, after applying the resin composition for the coating layer, it is preferably pre-dried at a relatively low temperature to first volatilize the solvent, and then dried at a high temperature, because a uniform film can be obtained. The temperature of the pre-drying is preferably 80 to 110°C, more preferably 85 to 105°C, and still more preferably 90 to 100°C. If the pre-drying temperature is less than 80°C, there is a risk of insufficient drying in the coating layer. Also, if the pre-drying temperature is greater than 110°C, drying will proceed before the coating layer spreads wet, and there is a risk of appearance defects.

[0045] On the one 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 less than 110 °C, film formation of the coating layer does not proceed, the cohesive force and adhesiveness decrease, and as a result, the barrier property may be adversely affected. If it exceeds 140 °C, the film may be overheated, becoming brittle, or the wrinkles due to heat shrinkage may increase.

[0046] The preferable 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. Also, the preferable drying time for this 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, since the drying conditions vary depending on the type of heat medium and the exhaust situation of the drying furnace, caution is required. Separately from drying, adding additional heat treatment in a low-temperature region as much as possible, specifically in the temperature range of 40 to 60 °C for 1 to 4 days, is even more effective in promoting film formation of the coating layer.

[0047] [Packaging Material] When the laminated film of the present invention is used as a packaging material, it is preferably a laminate formed with a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the coating layer, but may also be provided on the outer side of the base film layer (the surface opposite to the coating layer forming surface). The formation of the heat-sealable resin layer is usually carried out by an extrusion lamination method or a dry lamination method. As the thermoplastic polymer for forming the heat-sealable resin layer, any polymer capable of sufficiently exhibiting sealant adhesiveness may be used. For example, polyethylene resins such as olefin-based HDPE, LDPE, and LLDPE, polypropylene resin, ethylene-vinyl acetate copolymer, ethylene-α-olefin random copolymer, ionomer resin, etc. can be used. Among these, LLDPE or polypropylene resin, which has high versatility from the viewpoints of durability, seal strength, price, and mono-materialization, is particularly preferred. The thickness of the sealant layer is preferably 20 to 100 μm, more preferably 30 to 90 μm, and even more preferably 40 to 80 μm. If the thickness is less than 20 μm, sufficient seal strength may not be obtained, and it may be difficult to handle due to lack of stiffness. On the other hand, if the thickness exceeds 100 μm, the stiffness becomes strong, the handleability as a bag deteriorates, and the price may also increase.

[0048] [Adhesive layer] As the adhesive layer used in the present invention, general-purpose laminating adhesives can be used. For example, (solventless), aqueous, or hot-melt adhesives mainly composed of poly(ester)urethane-based, polyester-based, polyamide-based, epoxy-based, poly(meth)acrylic-based, polyethyleneimine-based, ethylene-(meth)acrylic acid-based, polyvinyl acetate-based, (modified) polyolefin-based, polybutadiene-based, wax-based, casein-based, etc. can be used. Among these, considering heat resistance and flexibility that can follow dimensional changes of each base material, urethane-based or polyester-based is preferable. As the lamination method of the above adhesive layer, for example, it can be applied by direct gravure coating method, reverse gravure coating method, kiss coating method, die coating method, roll coating method, dip coating method, knife coating method, spray coating method, fountain coating method, or other methods. To exhibit sufficient adhesiveness, the coating amount after drying is preferably 1 to 8 g / m 2 is preferable. More preferably, it is 2 to 7 g / m 2 , and even more preferably 3 to 6 g / m 2 . When the coating amount is less than 1 g / m 2 , it becomes difficult to bond over the entire surface, and the adhesive strength decreases. Also, when it exceeds 8 g / m 2 , it takes time for the film to completely cure, unreacted substances tend to remain, and the adhesive strength decreases.

[0049] Furthermore, in the laminated film of the present invention, at least one layer or more of a printing layer, other plastic base materials, and / or paper base materials may be laminated between or outside the base film layer and the heat-sealing resin layer.

[0050] As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks can be preferably used. Examples of the resin 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, antiblocking agents, and antioxidants. The printing method for providing the printing 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 preferably has an oxygen permeability of 50 ml / m 2 ·d·MPa or less under the conditions of 23°C × 65% RH in terms of exhibiting good gas barrier properties. Furthermore, by controlling the coating layer components, coating amounts, etc. as described above, it is preferably 40 ml / m 2 ·d·MPa or less, more preferably 30 ml / m 2 ·d·MPa or less. When the oxygen permeability exceeds 50 ml / m 2 ·d·MPa, it becomes difficult to meet the requirements for applications that require high gas barrier properties. On the other hand, if the oxygen permeability is less than 1 ml / m 2 ·d·MPa in all cases, although the barrier performance is excellent, the residual solvent hardly permeates to the outside of the bag, and there is a risk that the amount of migration to the contents relatively increases, which is not preferable. The preferable lower limit of the oxygen permeability is 1 ml / m 2 ·d·MPa or more.

[0052] The laminate of the present invention preferably has a water vapor permeability of 4.0 g / m 2 ·d or less under the conditions of 40°C × 90% RH in terms of exhibiting good gas barrier properties. Furthermore, by controlling the coating layer components and coating amounts as described above, it is preferably 3.5 g / m 2 ·d or less, more preferably 3.0 g / m 2·d or less. If the water vapor transmission rate exceeds 4.0 g / m 2 ·d, it becomes difficult to meet the applications that require high gas barrier properties. On the other hand, if the water vapor transmission rate is all less than 0.1 g / m 2 , although the barrier performance is excellent, the residual solvent hardly permeates to the outside of the bag, and there is a possibility that the amount of migration to the contents relatively increases, which is not preferable. The preferable lower limit of the water vapor transmission rate is 0.1 g / m 2 ·d or more.

[0053] The laminate of the present invention preferably has a laminate strength of 1.0 N / 15 mm or more, more preferably 1.5 N / 15 mm or more, and even more preferably 2.0 N / 15 mm or more under the conditions of 23°C × 65% RH. If the laminate strength is less than 1.0 N / 15 mm, peeling may occur due to the bending load or heat during sealing, resulting in deterioration of the barrier property or leakage of the contents. Furthermore, there is also a possibility that the cutability deteriorates.

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 evaluation of the film was carried out by the following measurement methods.

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

[0056] (2) Haze of the laminated film Measured using a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JISK7136.

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

[0058] (4) Measuring method for total reflection infrared absorption spectrum of laminated film In each of the examples and comparative examples, for the surface of the coating layer of each single laminated film obtained at the stage of laminating the coating layer on the base film, the total reflection infrared absorption spectrum was measured by total reflection absorption infrared spectroscopy, and the peak intensity (P1) having an absorption maximum in the region of 1040 ± 10 cm-1 and the peak intensity (P2) having an absorption maximum in the region of 3000 ± 10 cm-1 were determined, and the intensity ratio (P1 / P2) was calculated. The calculation of each peak intensity was performed from the peak height obtained by vertically connecting the baseline with an absorbance of zero and each peak top.

[0059] (5) Measuring method for arithmetic mean roughness of coating layer The surface roughness of the laminated film was measured using a scanning probe microscope (SPM) ("SPM9700" manufactured by Shimadzu Corporation) (cantilever: OMCL-AC200TS provided by Olympus Corporation, observation mode: phase mode). Specifically, an SPM image was obtained in a field of view angle of 2 μm square on the film surface. In the obtained image, after performing tilt correction in the X direction, Y direction, and Z direction using the tilt correction function of the software attached to the SPM, the value of the arithmetic mean roughness was calculated. The arithmetic mean roughness is obtained by removing the surface undulation component longer than a predetermined wavelength from the cross-sectional curve by a high-pass filter, extracting only the reference length in the direction of the average line of the extracted portion, taking the X axis in the direction of the average line of the extracted portion and the Y axis in the direction of the vertical magnification, and when the roughness curve is represented by y = f(X), the value obtained by expanding the following formula to two dimensions was used as the value. Ra = 1 / L ∫L0 |f(x)|dx L: reference length

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

[0061] (7) Method for evaluating water vapor permeability In each of the examples and comparative examples, each laminated film obtained at the stage of laminating the coating layer on the base film was used as a sample, and in accordance with JIS-K7129 B method, using a water vapor permeability measuring device ("PERMATRAN-W 3 / 33MG" manufactured by MOCON), the water vapor permeability was measured in an atmosphere of 40°C and 90% RH. The measurement of the water vapor permeability was carried out in the direction in which water vapor permeates from the base film side to the coating layer side.

[0062] (8) Evaluation of blocking resistance of laminated film In each of the examples and comparative examples, each laminated film obtained at the stage of laminating the coating layer on the base film was used as a sample. Two sets of samples cut into strips with a width of 15 mm and a length of 200 mm were prepared. After dropping one drop (about 0.02 g) of water on the coating layer surface of one side of the sample, the other sample was overlapped so that the coating layer surfaces were combined, sandwiched between glass plates, dried at 40°C for 24 hours to evaporate the moisture, and then the two strips were peeled off to check the adhesion state of the films. When peeling, those with such strong adhesion that the film was torn were judged as ×, and those that could be smoothly peeled off without the film being torn were judged as 〇.

[0063] (9) Evaluation of solvent volatility of coating layer In each of the examples and comparative examples, each laminated film obtained at the stage of laminating the coating layer on the base film was used as a sample. When the coating layer was gently pressed with a paper towel, those in which the coating layer adhered to the paper towel were judged as × for insufficient solvent volatilization, and those in which the coating layer did not adhere to the paper towel were judged as 〇 for sufficient solvent volatilization.

[0064] (10) Appearance evaluation of the coating layer In each of the examples and comparative examples, each laminated film obtained at the stage of laminating the coating layer on the base film was used as a sample. Those with visible peeling, streaks, unevenness, etc. of the coating layer were judged as × (poor appearance), and those without the above were judged as 〇 (good appearance) by visual inspection.

[0065] (11) Evaluation of heat shrinkage rate at 150°C for 5 minutes In each of the examples and comparative examples, a test piece with a width of 20 mm and a length of 300 mm was prepared so that the measurement direction (MD or TD) of the prepared film was the long side, and markings were made at a distance of 200 mm at the center of the test piece. Then, the distance between the markings was read with a ruler to the first decimal place, and the distance A between the markings before heating was obtained. Then, the ends of this test piece were clamped with clips and placed in a heating oven maintained at 150°C ± 1°C for 5 minutes while hanging on a metal bar. After heating, the distance between the markings of the taken-out test piece was read with a ruler in the same way as before heating, and the distance B between the markings after heating was obtained. Based on the obtained values, the heat shrinkage rate was calculated using the following formula. Heat shrinkage rate (%) = (A - B) / A × 100 (12) Evaluation of heat shrinkage rate at 120°C for 5 minutes In each of the examples and comparative examples, a test piece with a width of 20 mm and a length of 300 mm was prepared so that the measurement direction (MD or TD) of the prepared film was the long side, and markings were made at a distance of 200 mm at the center of the test piece. Then, the distance between the markings was read with a ruler to the first decimal place, and the distance A between the markings before heating was obtained. Then, the ends of this test piece were clamped with clips and placed in a heating oven maintained at 120°C ± 1°C for 5 minutes while hanging on a metal bar. After heating, the distance between the markings of the taken-out test piece was read with a ruler in the same way as before heating, and the distance B between the markings after heating was obtained. Based on the obtained values, the heat shrinkage rate was calculated using the following formula. Heat shrinkage rate (%) = (A - B) / A × 100

[0066] [Preparation of printed matter] On the laminates obtained in the examples and comparative examples, white ink (NEW LP Super R631AD White N manufactured by Toyo Ink Co., Ltd.) was applied so that the ink layer after drying treatment at a maximum temperature of 120 °C during drying became 0.1 g / m 2 After that, each printed product was obtained by storing at 40 °C for 1 day. (13) Evaluation of finish quality during printing The printed products prepared above were visually inspected. Those with noticeable wrinkles or sags on the substrate were judged as × with poor finish quality, and those without such were judged as 〇 with good finish quality.

[0067] [Production of laminated body] On the laminates obtained in the examples and comparative examples, a polyurethane-based adhesive (Takelac A525S / Takenate A50 manufactured by Mitsui Chemicals, Inc.) was applied so that the thickness after drying treatment at a maximum temperature of 120 °C during drying became 3 μm. Then, an unstretched polypropylene film (P1128 manufactured by Toyobo Co., Ltd.; thickness 30 μm; designated as CPP) was dry-laminated on a metal roll heated to 60 °C, and aging was performed at 40 °C for 4 days to obtain an evaluation laminated gas barrier laminate (hereinafter sometimes referred to as "laminated body a").

[0068] (14) Evaluation method for laminate strength The laminated body prepared above was cut into test pieces with a width of 15 mm and a length of 200 mm. Under the conditions of a temperature of 23 °C and a relative humidity of 65%, the laminate strength (normal state) was measured using a Tensilon universal material testing machine ("Tensilon UMT-II-500 type" manufactured by Toyo Baldwin Co., Ltd.). In addition, for the measurement of the laminate strength, the tensile speed was set to 200 mm / min, and the strength when the laminate film layer and the heat-sealability resin layer of each laminated film obtained in the examples and comparative examples were peeled at a peeling angle of 90 degrees was measured. (15) Evaluation of finish quality during dry lamination The laminated body prepared above was visually inspected. Those with noticeable wrinkles or sags on the substrate were judged as × with poor finish quality, and those without such were judged as 〇 with good finish quality.

[0069] [Production of bagged products] Using the laminate laminate produced above, a cut sheet of A4 size was created. This cut sheet was folded in half so that the CPP sides faced each other, and the four sides were pressure-heat sealed under the following seal conditions using a test sealer "Type TYB-300" manufactured by Nishi Machinery Co., Ltd. to create a bagged product. Seal conditions (width of seal bar: 10 mm, seal bar: heating temperature 160 ± 1 °C, seal bar pressure: 0.2 MPa, seal time: 2 seconds, cooling time: 1 second) (16) Evaluation of finish at the time of bag-making seal The vicinity of the seal part of the bagged product produced above was visually inspected, and those with conspicuous wrinkles or sagging on the base material were judged as × for poor finish, and those without the above were judged as 〇 for good finish.

[0070] The details of the coating liquids used in the following examples and comparative examples are described below. Note that they were used in Examples 1 to 6 and Comparative Examples 1 to 10 and are shown in Table 1.

[0071] [Polyvinyl alcohol resin (A)] To 90 parts by mass of purified water, 10 parts by mass of a completely saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: G Polymer OKS8049Q, (saponification degree 99.0% or more, average degree of polymerization 450)) was added, and the mixture was heated to 80 °C while stirring, and then stirred for about 1 hour. Thereafter, 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)] 5 parts by mass of montmorillonite (trade name: Kunipia F, manufactured by Kunimine Industries Co., Ltd.), which is an inorganic layered compound, was added to 95 parts by mass of purified water while stirring and sufficiently dispersed using a homogenizer at a setting of 1500 rpm. Thereafter, it was kept warm at 23 °C for 1 day to obtain an inorganic layered compound dispersion with a solid content of 5%.

[0073] [Coating liquid 1 used for the coating layer] Each material was mixed at the following mixing ratio to prepare a coating liquid (resin composition for the coating layer). Ion-exchanged water 20.00 mass% Isopropyl alcohol 15.00 mass% Polyvinyl alcohol resin (A) 35.00 mass% Inorganic layered compound dispersion (B) 30.00 mass%

[0074] [Coating liquid 2 used for the coating layer] Each material was mixed at the following mixing ratios to prepare a coating liquid (resin composition for the coating layer). Ion-exchanged water 15.00 mass% Isopropyl alcohol 15.00 mass% Polyvinyl alcohol resin (A) 30.00 mass% Inorganic layered compound dispersion (B) 40.00 mass%

[0075] [Coating liquid 3 used for the coating layer] Each material was mixed at the following mixing ratios to prepare a coating liquid (resin composition for the coating layer). Ion-exchanged water 10.00 mass% Isopropyl alcohol 15.00 mass% Polyvinyl alcohol resin (A) 25.00 mass% Inorganic layered compound dispersion (B) 50.00 mass%

[0076] [Coating liquid 4 used for the coating layer] Each material was mixed at the following mixing ratios to prepare a coating liquid (resin composition for the coating layer). Ion-exchanged water 5.00 mass% Isopropyl alcohol 15.00 mass% Polyvinyl alcohol resin (A) 20.00 mass% Inorganic layered compound dispersion (B) 60.00 mass%

[0077] [Coating liquid 5 used for the coating layer] Each material was mixed at the following mixing ratios to prepare a coating liquid (resin composition for the coating layer). Ion-exchanged water 35.00 mass% Isopropyl alcohol 15.00 mass% Polyvinyl alcohol resin (A) 50.00% by mass

[0078] [Coating liquid 6 for the coating layer] Each material was mixed at the following mixing ratios to prepare a coating liquid (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 7 for the coating layer] Each material was mixed at the following mixing ratios to prepare a coating liquid (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 8 for the coating layer] The following materials were mixed at the mass ratios shown below and stirred for 30 minutes or more to dissolve. Then, undissolved matter was removed using a filter with a nominal filtration accuracy of 50 μm to prepare a coating liquid (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 Corporation, solid content ratio 48%)

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

[0082] In this way, a laminated film having a coating layer on a base film was produced. As the base material, for Examples 1 to 6, Comparative Examples 1 to 6, 8 to 10, a film of Pyren film high heat resistance and high rigidity type P2171, a static prevention material-free, and a thickness of 20 μm manufactured by Toyobo Co., Ltd. was used. For Comparative Example 7, an ester film E5100 manufactured by Toyobo Co., Ltd. and having a thickness of 12 μm was used. For Comparative Example 11, a Pyren film P2102 manufactured by Toyobo Co., Ltd. and having a thickness of 20 μm was used. Evaluation was carried out on the obtained laminated film. 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 film capable of forming a laminate structure composed of substantially a single resin type with less environmental load mainly composed of a polypropylene film, and a laminated film having necessary performances such as gas barrier properties and adhesiveness 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 economic efficiency and production stability, and can provide a gas barrier film with homogeneous characteristics.

Claims

1. A laminated film provided with a coating layer having a polyvinyl alcohol-based copolymer and an inorganic layered compound on at least one side of a base film, wherein the laminated film satisfies the following requirements (a) to (f). (a) The base film is a stretched film made of a propylene-based resin. (b) The coating amount of the coating layer is 0.10 g / m ２ or more and 0.50 g / m ２ or less. (c) In the total reflection infrared absorption spectrum of the laminated film, the ratio (P1 / P2) of the peak intensity (P1) having an absorption maximum in the region of 1040 ± 10 cm －１ and the peak intensity (P2) having an absorption maximum in the region of 3300 ± 10 cm －１ 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 10% in both the MD direction and the TD direction. (e) The arithmetic mean roughness in a 2-μm square of the coating layer on the laminated film is in the range of 2.0 to 8.0 nm. (f) The oxygen permeability of the laminated film in an environment of 23°C and 65% RH is 50 ml / m 2 ·d·MPa or less, and the water vapor permeability in an environment of 40°C and 90% RH is 4 g / m 2 ·d or less.

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

4. A packaging material obtained by laminating an olefin-based sealant layer on one side of the laminated film according to any one of claims 1 to 3.

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