Polymer film, barrier film, laminate, and packaging bag

Abstract

This polymer film 10 is characterized by comprising a first resin layer 11, a second resin layer 12, and a third resin layer, in that order. The polymer film is also characterized in that: the first resin film 11 forms one outermost layer of the polymer film 10; the first resin layer 11 includes a polyamide resin; the polyamide resin includes a copolymer polyamide that is a polycondensation product of diamine units and dicarboxylic acid units; the proportion of the number of aromatic diamine units to the total number of diamine units included in the polyamide resin that forms the first resin layer 11 is at least 75 mol%; the proportion of the number of isophthalic acid units to the total number of dicarboxylic acid units included in the polyamide resin that forms the first resin layer 11 is at least 22 mol%; the second resin layer 12 includes acid-denatured polypropylene; and the third resin layer 13 includes homopolypropylene.

Description

Polymer films, barrier films, laminates and packaging bags

[0001] The present disclosure relates to polymeric films, barrier films, laminates, and packaging bags.

[0002] Flexible packaging materials are constructed by laminating multiple films. A polyester film such as polyethylene terephthalate is used to impart strength and heat resistance to the packaging material, a polyamide 6 film is used to impart pinhole resistance, and a polypropylene film is used to impart strength and water vapor barrier properties. These films are usually biaxially oriented to provide printability.

[0003] The biaxially stretched film is printed as needed, and an unstretched film made of polyethylene or polypropylene, which is usually not stretched, is laminated on the printed surface. By heat-sealing the two inner surfaces of the unstretched polyethylene or polypropylene film on the inside, a packaging bag is produced from a laminate of multiple films.

[0004] In order to impart barrier properties to the packaging bag, a layer made of aluminum foil, a film vapor-deposited with aluminum, alumina or silicon oxide, an ethylene-vinyl alcohol copolymer, polyvinyl alcohol, or the like is provided between the biaxially stretched film and the unstretched film.

[0005] Flexible packaging materials can be made into multi-layers of multiple different materials to meet required performance and be used to package a variety of contents. In recent years, there has been a demand for recycling flexible packaging materials as well in order to reduce carbon dioxide emissions, which are considered to be the main cause of global warming. Since it is extremely difficult to recycle packaging materials made from different materials, the trend toward mono-materialization, which is made from a single material, has become a means of making flexible packaging materials recyclable. Polyolefins, which are easily recyclable, are considered to be preferable as mono-material materials.

[0006] Packaging bags for heat sterilization are filled with the contents, sealed, and then boiled or retorted. Heated contents may also be filled. Because these processes involve heat treatment of the packaging bag, it is more appropriate to use polypropylene, which has higher heat resistance than polyethylene, for the unstretched film used for heat sealing. When polypropylene is used as a component of the packaging material, the polypropylene film is endowed with properties suitable for packaging, such as printability, barrier properties, heat sealability, and lamination. Printing is performed on a strong biaxially oriented polypropylene film. Heat sealing is performed using an unstretched polypropylene film.

[0007] To provide packaging materials with barrier properties while enabling recycling, it is considered appropriate to use polypropylene films vapor-deposited with alumina or silicon oxide. Therefore, films in which inorganic oxides such as alumina or silicon oxide are vapor-deposited on polypropylene films have been proposed as mono-material packaging films.

[0008] However, even if an inorganic oxide is vapor-deposited on the surface of a polypropylene film, the barrier properties may not be exhibited due to the fine irregularities on the surface of the stretched polypropylene film. Furthermore, the adhesive strength between the vapor-deposited inorganic oxide and the polypropylene film surface may be low, resulting in insufficient physical properties of the laminate. Therefore, to compensate for the disadvantages of polypropylene film against vapor deposition, it has been proposed to provide a layer containing a resin material having a melting point of 180°C or higher on one side of a biaxially oriented polypropylene film and vapor-deposit an inorganic oxide on the surface of this layer (Patent Document 1).

[0009] Japanese Patent Application Laid-Open No. 2022-7964

[0010] Patent Document 1 lists polyamide as a resin material having a melting point of 180°C or higher. Polyamide resins include those containing aminocarboxylic acid as a structural unit (e.g., polyamide 6) and those containing diamine and dicarboxylic acid as structural units (e.g., polyamide 66). Polyamide resins containing a large amount of aromatic diamine as a structural unit (e.g., MXD6) are known to have high heat resistance. Therefore, in order to improve the heat resistance of packaging bags for heat sterilization, it is conceivable to use a polyamide resin containing a large amount of aromatic diamine as a structural unit as a resin material having a melting point of 180°C or higher. Furthermore, since polyamide resins containing a large amount of aromatic diamine as a structural unit are harder than polypropylene, using a layer formed from a polyamide resin containing a large amount of aromatic diamine as a structural unit as a layer on which inorganic oxides are vapor-deposited facilitates migration of the inorganic oxides, allowing the formation of a dense vapor-deposited film. As a result, gas barrier properties such as oxygen barrier property and water vapor barrier property are improved. However, when the proportion of aromatic diamine contained as a structural unit in a polyamide resin is increased, there is a problem that it becomes difficult to form the polyamide resin into a film.

[0011] Furthermore, when a packaging bag is heat sterilized, the film constituting the packaging bag expands or contracts, generating stress between the layers, and heating in a state in which stress acts between the layers can cause delamination between the film layers.There has been a need to suppress delamination in a polymer film in which a layer containing a polyamide resin is provided on one side of a polypropylene film.

[0012] Therefore, an object of the present disclosure is to provide a polymer film that is excellent in heat resistance, gas barrier property, film-forming property, and recyclability, and that can suppress delamination. Another object of the present disclosure is to provide a barrier film, a laminate, and a packaging bag that use the polymer film.

[0013] The present inventors have focused on the fact that polyamide resins containing a large amount of isophthalic acid as a structural unit are amorphous and that amorphous resins are easily stretched and suitable for film formation. They have discovered that increasing the proportion of isophthalic acid contained as a structural unit in a polyamide resin improves the film-forming properties of a polymer film having a layer containing a polyamide resin while maintaining high heat resistance and high gas barrier properties. Furthermore, the present inventors have focused on the fact that an acid-modified polypropylene is a polypropylene-based resin with high adhesiveness. They have discovered that providing a layer containing an acid-modified polypropylene between a polypropylene film and a layer containing a polyamide resin that constitute a polymer film can suppress interlayer delamination of the polymer film without impairing the recyclability of the polymer film. The present disclosure has been completed based on these findings and through further investigation.

[0014] The present disclosure is solved by the following embodiments. <1> A polymer film including a first resin layer, a second resin layer, and a third resin layer in this order, wherein the first resin layer constitutes one of the outermost layers of the polymer film, the first resin layer contains a polyamide resin, and the polyamide resin contains a copolymerized polyamide that is a polycondensate of diamine units and dicarboxylic acid units, the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 75 mol% or more, the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is 22 mol% or more, the second resin layer contains an acid-modified polypropylene, and the third resin layer contains homopolypropylene. <2> The polymer film according to <1>, wherein the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 75 mol% or more and 95 mol% or less. <3> The polymer film according to <1> or <2>, wherein the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is 22 mol% or more and less than 45 mol%. <4> The polymer film according to any one of <1> to <3>, wherein the first resin layer contains one type of copolyamide. <5> The polymer film according to <4>, wherein the content of the copolyamide in the first resin layer is 70 mass% or more. <6> The polymer film according to any one of <1> to <3>, wherein the copolyamide in the first resin layer is two types, a first copolyamide and a second copolyamide. <7> The polymer film according to <6>, wherein the content of the first copolyamide in the first resin layer is 5 mass% or more and 24 mass% or less. <8> The polymer film according to <6> or <7>, wherein the content of the second copolyamide in the first resin layer is 76 mass% or more and 95 mass% or less. <9> The polymer film according to any one of <1> to <8>, wherein the content of polypropylene in the polymer film is 70% by mass or more.<10> The polymer film according to any one of <1> to <9>, wherein the third resin layer has the greatest thickness among the first resin layer, the second resin layer, and the third resin layer, and wherein the thicknesses of the layers constituting the polymer film satisfy the following formulas (1) and (2): Thickness of first resin layer≦(thickness of polymer film) / 10 (1) Thickness of second resin layer≦(thickness of polymer film) / 5 (2) <11> The polymer film according to any one of <1> to <10>, wherein the polymer film further comprises a fourth resin layer on the opposite side of the third resin layer from the second resin layer, the fourth resin layer containing a copolymer of propylene and an olefin other than propylene. <12> A barrier film comprising the polymer film according to any one of <1> to <11> and a vapor-deposited film containing an inorganic oxide, wherein the vapor-deposited film is provided on the first resin layer side. <13> The barrier film according to <12>, wherein a barrier coat layer is provided on the vapor-deposited film side. <14> A laminate comprising the barrier film according to <12> or <13> and a heat sealant film. <15> The laminate according to <14>, further comprising a polypropylene base film. <16> A packaging bag comprising the laminate according to <14> or <15>.

[0015] The present disclosure provides a polymer film that is excellent in heat resistance, gas barrier property, film-forming property, and recyclability and that can suppress interlayer delamination. The present disclosure also provides a barrier film, a laminate, and a packaging bag that use the polymer film.

[0016] Fig. 1 is a schematic cross-sectional view showing one embodiment of a polymer film according to the present disclosure; Fig. 2 is a schematic cross-sectional view showing another embodiment of a polymer film according to the present disclosure; Fig. 3 is a schematic cross-sectional view showing one embodiment of a barrier film according to the present disclosure; Fig. 4 is a schematic cross-sectional view showing another embodiment of a barrier film according to the present disclosure; Fig. 5 is a schematic cross-sectional view showing one embodiment of a barrier film according to the present disclosure provided with a barrier coat layer; Fig. 6 is a schematic cross-sectional view showing one embodiment of a laminate according to the present disclosure; Fig. 7 is a schematic cross-sectional view showing another embodiment of a laminate according to the present disclosure.

[0017] In this specification, when multiple upper limit candidate values ​​and multiple lower limit candidate values ​​are listed for a certain parameter, the numerical range of the parameter may be formed by combining any one upper limit candidate value and any one lower limit candidate value. As an example, consider the following statement: "Parameter B is preferably A1 or more, more preferably A2 or more, even more preferably A3 or more, and preferably A4 or less, more preferably A5 or less, and even more preferably A6 or less." In this example, the numerical range of parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[0018] (Polymer Film) A schematic cross-sectional view of a polymer film 10 according to an embodiment of the present disclosure is shown in Fig. 1. The polymer film 10 includes a first resin layer 11, a second resin layer 12, and a third resin layer 13, in this order. The first resin layer 11 constitutes one of the outermost layers of the polymer film 10. The third resin layer 13 constitutes the other outermost layer of the polymer film 10.

[0019] 2 shows a schematic cross-sectional view of a polymer film 10 according to another embodiment of the present disclosure. The polymer film 10 includes, in this order, a first resin layer 11, a second resin layer 12, a third resin layer 13, and a fourth resin layer 14. The first resin layer 11 constitutes one of the outermost layers of the polymer film 10. The fourth resin layer 14 constitutes the other outermost layer of the polymer film 10.

[0020] As shown in FIG. 3, a vapor-deposited film 15 is provided on the first resin layer side of the polymer film 10 of the present disclosure to serve as a barrier film.

[0021] Each layer included in the polymer film 10 of the present disclosure will be described below.

[0022] (First Resin Layer) The first resin layer 11 contains a polyamide resin, and the polyamide resin contains a copolymer polyamide. The copolymer polyamide is a polyamide resin that is a polycondensate of a diamine unit and a dicarboxylic acid unit. When the first resin layer 11 contains the copolymer polyamide, the gas barrier property of the polymer film 10 is improved.

[0023] Examples of diamines that can be used as diamine units include linear aliphatic diamines such as 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine (hexamethylenediamine), 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine; 2-methyl-1,8-octanediamine, 4-methyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine; and 2,2,4- / 2,4,4-trimethyl-1,8-octanediamine. Examples of the diamine include branched aliphatic diamines such as methyl-1,6-hexanediamine, 2-methyl-1,5-pentanediamine (2-methylpentamethylenediamine), 2-methyl-1,6-hexanediamine, and 2-methyl-1,7-heptanediamine; alicyclic diamines such as isophoronediamine, norbornanedimethylamine, and tricyclodecanedimethylamine; and aromatic diamines such as metaxylylenediamine (metaxylylenediamine, MXD), paraxylylenediamine, metaphenylenediamine, and paraphenylenediamine.

[0024] Examples of dicarboxylic acids that can be used as the dicarboxylic acid unit include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, eicosanedionic acid, eicosadienedioic acid, and 2,2,4-trimethyladipic acid; aromatic dicarboxylic acids such as terephthalic acid (TPA) and isophthalic acid (IPA); and naphthalenedicarboxylic acids such as 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid.

[0025] Examples of copolymerized polyamides include aliphatic polyamides such as polyamide 410, 56, 66, 69, 610, 611, 612, and 1010; semi-aromatic polyamides such as polyamide 6T, 9T, 10T, 6I, and MXD6 (copolymers of metaxylenediamine and adipic acid), and MXD6I (copolymers of a mixture of metaxylenediamine, adipic acid, and isophthalic acid); polyamide 6 / 66, 6 / 12, 6 / 6T, 6 / 6I, and 6I / 6T (copolymers of 1,6-hexanediamine, isophthalic acid, and terephthalic acid), DI / DT (copolymers of 2-methyl-1,5-pentanediamine, isophthalic acid, and terephthalic acid), and 6 / MXD6.

[0026] The ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 75 mol% or more, preferably 78 mol% or more, and more preferably 80 mol% or more. Furthermore, the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 100 mol% or less, preferably 95 mol% or less, and more preferably 90 mol% or less. For example, the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 75 mol% or more and 100 mol% or less, preferably 78 mol% or more and 95 mol% or less, and more preferably 80 mol% or more and 90 mol% or less. Copolymerized polyamides are polyamide resins obtained by copolymerizing diamines and dicarboxylic acids, so diamine units are one of the constituent units of copolymerized polyamides. The "total number of diamine units contained in the polyamide resin constituting the first resin layer" corresponds to the total amount (mol) of diamine units contained in the polyamide resin constituting the first resin layer, and represents the amount of diamine units contained in the polyamide resin constituting the first resin layer. Furthermore, aromatic diamines are diamines containing a benzene ring and are a type of diamine. Therefore, the "proportion of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" represents the proportion of aromatic diamine units among all diamine units contained in the polyamide resin constituting the first resin layer. For example, if the first resin layer 11 is composed of 80 mass % copolymer polyamide X and 20 mass % copolymer polyamide Y, and the copolymer polyamide X contains 100 mol % of aromatic diamine units among its diamine units, and the copolymer polyamide Y contains 10 mol % of aromatic diamine units among its diamine units, the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 100 mol % × 80 / 100 + 10 mol % × 20 / 100 = 82 mol %.

[0027] When the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is equal to or greater than the lower limit, the heat resistance and gas barrier properties of the polymer film are improved.

[0028] The ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is 22 mol% or more, preferably 25 mol% or more, and more preferably 27 mol% or more. Furthermore, the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is preferably less than 45 mol%, more preferably 35 mol% or less. For example, the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is preferably 22 mol% or more but less than 45 mol%, more preferably 25 mol% or more but 35 mol%, and even more preferably 27 mol% or more but 35 mol%. Copolymerized polyamides are polyamide resins obtained by copolymerizing diamines and dicarboxylic acids, so dicarboxylic acid units are one of the constituent units of copolymerized polyamides. The "total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" corresponds to the total amount (mol) of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer, and represents the amount of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer. Isophthalic acid is a type of dicarboxylic acid. Therefore, the "ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" represents the ratio of isophthalic acid units to all dicarboxylic acid units contained in the polyamide resin constituting the first resin layer. For example, if the first resin layer 11 is composed of 80 mass % copolymer polyamide X and 20 mass % copolymer polyamide Y, and the copolymer polyamide X contains 15 mol % of isophthalic acid units in its dicarboxylic acid units, and the copolymer polyamide Y contains 70 mol % of isophthalic acid units in its dicarboxylic acid units, the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is 15 mol % × 80 / 100 + 70 mol % × 20 / 100 = 26 mol %.

[0029] When the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is equal to or greater than the lower limit, the polyamide resin becomes amorphous and film formability is improved.When the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is equal to or less than the upper limit, the heat resistance of the polymer film is improved.

[0030] In reality, "the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" and "the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" are １ It is determined from the results of measuring the H-NMR spectrum. １ The H-NMR spectrum is measured, and the proportion of the number of each diamine unit and the proportion of the number of each dicarboxylic acid unit contained in the first resin layer are calculated, whereby the "proportion of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" and the "proportion of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" can be determined. １ The protons from which the peaks observed in the H-NMR spectrum are derived can be determined by the １ The ratio of the number of each diamine unit and the ratio of the number of each dicarboxylic acid unit contained in the first resin layer can be determined from the area ratio of each peak.

[0031] Prepare a measurement sample from a polymer film. １ When measuring H-NMR spectrum, １The H-NMR spectrum is measured as follows: The polymer film is cut into small pieces with scissors and placed in a sample vial. 6 mL of chloroform and 4 mL of formic acid are added to the sample vial and left to stand overnight. In this way, the first resin layer constituting the polymer film is dissolved in a mixed solvent of chloroform and formic acid. The organic solvent phase is filtered through a chromatodisc with a filter pore size of 0.45 μm, and concentrated and dried using a nitrogen blowing device to obtain a measurement sample. 20 to 30 mg of the measurement sample is dissolved in deuterated chloroform (CDCl ３ The resulting solution was dissolved in a mixed solvent of 0.5 mL of acetic acid and 0.5 mL of formic acid, and transferred to an NMR sample tube. Measurement was performed using an NMR apparatus (AVANCE III HD 400 MHz, manufactured by Bruker Japan Co., Ltd.) under the following measurement conditions: １ H-NMR spectrum measurement is performed. (Measurement conditions) Measurement nuclides: １ Measurement temperature: room temperature Number of scans: 32 Waiting time: 5 seconds Probe: PA BBO 400S1 BBF-H-D-05 Z SP Deuterated solvent: CDCl ３ (Internal standard: TMS) + formic acid Window function: exponential Spectral line width: 0.3 Hz

[0032] Prepare a measurement sample from the barrier film. １ When measuring H-NMR spectrum, a measurement sample is prepared from a polymer film. １ In the same manner as in measuring the H-NMR spectrum, １ H-NMR spectrum is measured.

[0033] Prepare a measurement sample from the laminate. １ When measuring H-NMR spectrum, １The H-NMR spectrum is measured as follows. The laminate is cut into small pieces with scissors, freeze-pulverized, and then placed in a sample vial. A mixed solvent of chloroform and formic acid (1:1) is added to the sample vial, and the vial is placed in an ultrasonic cleaner for 10 minutes, and then left to stand overnight. The organic solvent phase is filtered through a chromatographic disk with a filter pore size of 0.45 μm, and concentrated and dried using a nitrogen blowing device. 10 mL of chloroform is added to the dried product, and the product is placed in an ultrasonic cleaner for 2 to 3 minutes. The product is filtered through filter paper 5C, and the filtrate is washed with chloroform. The filtrate together with the filter paper 5C is dried with nitrogen blowing, and then the filtrate is dissolved in formic acid, and the filtrate is recovered. The recovered filtrate is dried with nitrogen blowing and used as a measurement sample. Thereafter, the same procedure as above is repeated. １ H-NMR spectrum is measured.

[0034] The copolymerized polyamide contained in the first resin layer may be one type or two or more types. When the copolymerized polyamide contained in the first resin layer is one type, the "ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" and the "ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" can be adjusted within the above-mentioned ranges by appropriately adjusting the type and ratio of monomers used in synthesizing the copolymerized polyamide. For example, by polycondensing a dicarboxylic acid containing 22 mol% or more of isophthalic acid with a diamine containing 75 mol% or more of aromatic diamine, the "ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" and the "ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" can be adjusted within the above-mentioned ranges. Furthermore, by forming the first resin layer from a resin composition in which two or more types of copolymerized polyamides are mixed in an appropriate ratio, the "ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" and the "ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer" may be adjusted within the above-mentioned ranges. From the viewpoint of easily adjusting the "ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer" and the "ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer," it is preferable that the copolymerized polyamide contained in the first resin layer be two or more types.

[0035] When the first resin layer contains one type of copolymerized polyamide, the content of the copolymerized polyamide in the first resin layer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. This improves the gas barrier properties of the polymer film 10. Furthermore, when the first resin layer contains one type of copolymerized polyamide, the upper limit of the content of the copolymerized polyamide in the first resin layer is 100% by mass. For example, when the first resin layer contains one type of polyamide resin, the content of the copolymerized polyamide resin in the first resin layer is preferably 70% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 100% by mass or less.

[0036] Next, the case where the copolymerized polyamide contained in the first resin layer is two types, a first copolymerized polyamide and a second copolymerized polyamide, will be described. When the copolymerized polyamide contained in the first resin layer is two types, a first copolymerized polyamide and a second copolymerized polyamide, the content of the first copolymerized polyamide in the first resin layer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 14% by mass or more, and preferably 24% by mass or less, more preferably 20% by mass or less, and even more preferably 18% by mass or less. For example, when the polyamide resin contained in the first resin layer is two types, a first copolymerized polyamide and a second copolymerized polyamide, the content of the first copolymerized polyamide in the first resin layer is preferably 5% by mass or more and 24% by mass or less, more preferably 10% by mass or more and 20% by mass or less, and even more preferably 14% by mass or more and 18% by mass or less. When the first resin layer contains two types of copolyamides, the first copolyamide and the second copolyamide, the content of the second copolyamide in the first resin layer is preferably 76% by mass or more, more preferably 80% by mass or more, even more preferably 82% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 86% by mass or less. For example, when the first resin layer contains two types of polyamide resins, the first copolyamide and the second copolyamide, the content of the second copolyamide in the first resin layer is preferably 76% by mass or more and 95% by mass or less, more preferably 80% by mass or more and 90% by mass or less, and even more preferably 82% by mass or more and 86% by mass or less.

[0037] Within the scope of the present disclosure, copolymerized polyamides may contain, in addition to diamine units and dicarboxylic acid units, copolymer units derived from compounds such as lactams (e.g., ε-caprolactam and laurolactam), aliphatic aminocarboxylic acids (e.g., aminocaproic acid and aminoundecanoic acid), and aromatic aminocarboxylic acids (e.g., p-aminomethylbenzoic acid). The proportion of copolymer units other than diamine units and dicarboxylic acid units is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less, even more preferably 5 mol% or less, and particularly preferably 0 mol%. For example, the proportion of copolymer units other than diamine units and dicarboxylic acid units is preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 20 mol% or less, even more preferably 0 mol% or more and 15 mol% or less, and even more preferably 0 mol% or more and 5 mol% or less.

[0038] The first resin layer 11 may contain a resin other than a copolymerized polyamide, as long as the effects of the present disclosure are not impaired. For example, it may contain a polyamide resin obtained by ring-opening polymerization of lactam (ring-opening polymerization polyamide), or may contain polyester, acrylic resin, ionomer resin, etc. The content of the resin other than a copolymerized polyamide in the first resin layer 11 is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, even more preferably 5% by mass or less, and particularly preferably 0% by mass. For example, the content of the resin other than a copolymerized polyamide in the first resin layer 11 is preferably 0% by mass or more to 30% by mass or less, more preferably 0% by mass or more to 20% by mass or less, even more preferably 0% by mass or more to 15% by mass or less, and even more preferably 0% by mass or more to 5% by mass or less.

[0039] The first resin layer 11 may contain additives such as a crosslinking agent, an antioxidant, an antiblocking agent, a lubricant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing agent, an antistatic agent, a pigment, and a modifying resin.

[0040] The ratio of the thickness of the first resin layer 11 to the total thickness of the polymer film 10 is preferably 1% or more, and more preferably 2% or more. This not only improves the gas barrier properties of the polymer film 10 due to the high gas barrier properties of the first resin layer 11, but also increases adhesion to the vapor-deposited film 15, further improving the gas barrier properties. Furthermore, the ratio of the thickness of the first resin layer 11 to the total thickness of the polymer film 10 is preferably 10% or less, and more preferably 5% or less. This further improves the film-forming and processability of the polymer film 10, and reduces the proportion of constituent materials other than polypropylene in the polymer film 10, thereby improving recyclability. For example, the ratio of the thickness of the first resin layer 11 to the total thickness of the polymer film 10 is preferably 1% or more and 10% or less, and more preferably 2% or more and 5% or less.

[0041] The thickness of the first resin layer 11 is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more. This not only improves the gas barrier properties of the polymer film 10 due to the high gas barrier properties of the first resin layer 11, but also increases adhesion to the vapor-deposited film 15, further improving the gas barrier properties. Furthermore, the thickness of the first resin layer is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 2 μm or less. This reduces the proportion of constituent materials other than polypropylene in the polymer film 10, improving recyclability. For example, the thickness of the first resin layer 11 is preferably 0.1 μm or more and 5 μm or less, more preferably 0.2 μm or more and 4 μm or less, and even more preferably 0.3 μm or more and 2 μm or less.

[0042] The first resin layer 11 may be subjected to a surface treatment, which can improve adhesion to the vapor-deposited film 15. The method of the surface treatment is not particularly limited, and examples thereof include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using one or more gases selected from the group consisting of argon gas, oxygen gas, and nitrogen gas, and glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals.

[0043] (Third Resin Layer) The third resin layer 13 has a polypropylene resin layer, which may be a single layer or a multi-layer including a regrind layer. By including the polypropylene resin layer in the third resin layer 13, heat resistance can be imparted to the polymer film 10.

[0044] The polypropylene contained in the polypropylene resin layer is primarily homopolypropylene, and may also contain polypropylene random copolymer and polypropylene block copolymer. Polypropylene random copolymer and polypropylene block copolymer may also be contained as layers or as a mixture. Homopolypropylene is a polymer of propylene alone, and polypropylene random copolymer is a random copolymer of propylene and an olefin other than propylene (e.g., ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, etc.). Polypropylene block copolymer is a copolymer having a polymer block of propylene and a polymer block of the above-mentioned olefin other than propylene. The third resin layer 13 preferably contains 51% by mass or more of homopolypropylene, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0045] A random copolymer may be added in addition to homopolypropylene to impart good transparency to the third resin layer 13. When producing a packaging bag using a laminate in which another film is laminated to a barrier film, if emphasis is placed on rigidity and heat resistance, it is preferable to use only homopolypropylene, and if emphasis is placed on impact resistance, it is preferable to add polypropylene random copolymer and / or polypropylene block copolymer to homopolypropylene, or to use polypropylene random copolymer and / or polypropylene block copolymer. Biomass-derived polypropylene and mechanically or chemically recycled polypropylene can also be used.

[0046] The first resin layer 11 preferably does not contain polypropylene, while the second resin layer 12 and the third resin layer contain polypropylene, and the polypropylene content in the polymer film 10 is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, thereby improving the recyclability of the polymer film.

[0047] The third resin layer 13 may contain a resin material other than polypropylene as long as the properties of the present disclosure are not impaired. Examples of the resin material other than polypropylene include polyolefins such as polyethylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamide resins, polyesters, and ionomer resins.

[0048] The third resin layer 13 may contain additives as long as the properties of the present disclosure are not impaired. Examples of additives include crosslinking agents, antioxidants, antiblocking agents, lubricants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, and modifying resins as compatibilizers.

[0049] The thickness of the third resin layer 13 is preferably 10 μm or more, and more preferably 15 μm or more. This further improves the strength and heat resistance of the polymer film 10. The thickness of the third resin layer 13 is also preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. This further improves the film formability, processability, and productivity of the polymer film 10. For example, the thickness of the third resin layer 13 is preferably 10 μm or more and 50 μm or less, more preferably 15 μm or more and 40 μm or less, and even more preferably 15 μm or more and 30 μm or less.

[0050] (Second Resin Layer) The second resin layer 12 contains an acid-modified polypropylene. The acid-modified polypropylene is a resin with high adhesiveness. By including the acid-modified polypropylene in the second resin layer 12, the polyamide contained in the first resin layer 11 and the polypropylene of the third resin layer are bonded together, thereby improving the interlayer adhesion between the first resin layer 11 and the third resin layer 13. Furthermore, since the acid-modified polypropylene is a polypropylene-based resin like the homopolypropylene that is the constituent material of the third resin layer 13, employing the acid-modified polypropylene as the resin constituting the second resin layer 12 can improve the recyclability of the polymer film 10.

[0051] Acid-modified polypropylene is obtained by graft polymerizing polypropylene with an unsaturated compound having one or more carboxylic acid groups, an ester of an unsaturated carboxylic acid compound having a carboxylic acid group with an alkyl alcohol, or an unsaturated compound having one or more carboxylic acid anhydride groups. The graft polymerization ratio is preferably 1 mol% to 2 mol%. It is more preferable that the graft polymerization ratio is 1 mol% to 2 mol% and the polymer film 10 is a stretched film. Examples of unsaturated groups include vinyl groups, vinylene groups, and unsaturated cyclic hydrocarbon groups. Furthermore, unsaturated compounds having a carboxylic acid group can be used alone or in combination of two or more. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, nadic acid, and endo-cis-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acid. As the unsaturated compound having one or more carboxylic acid anhydride groups, maleic anhydride is preferred.

[0052] In the acid-modified polypropylene, the polypropylene to be acid-modified is a homopolypropylene, a polypropylene random copolymer, or a polypropylene block copolymer, and a plurality of these may be used. Furthermore, a mixture of the respective acid-modified products may be used. It is particularly preferable that the main component is a polypropylene random copolymer. A polypropylene random copolymer is a random copolymer of propylene and an olefin other than propylene. A polypropylene block copolymer is a copolymer having a polymer block made of propylene and a polymer block made of the above-mentioned olefin other than propylene.

[0053] The acid-modified polypropylene may be commercially available, such as the Admer series manufactured by Mitsui Chemicals, Inc. or the Modic series manufactured by Mitsubishi Chemical Corporation.

[0054] The thickness of the second resin layer 12 is preferably 0.2 μm or more, and more preferably 0.5 μm or more. This further improves the adhesion between the first resin layer 11 and the third resin layer 13. The thickness of the second resin layer 12 is also preferably 15 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less. This improves the processability of the polymer film 10. For example, the thickness of the second resin layer 12 is preferably 0.2 μm or more and 15 μm or less, more preferably 0.5 μm or more and 5 μm or less, and even more preferably 0.5 μm or more and 2 μm or less.

[0055] The ratio of the thickness of the second resin layer 12 to the total thickness of the polymer film 10 is preferably 1% or more, and more preferably 2% or more. This improves the adhesion between the first resin layer 11 and the third resin layer 13. Furthermore, the ratio of the thickness of the second resin layer 12 to the total thickness of the polymer film 10 is preferably 20% or less, and more preferably 10% or less. This improves processability and reduces costs. For example, the ratio of the thickness of the second resin layer 12 to the total thickness of the polymer film 10 is preferably 1% or more and 20% or less, and more preferably 2% or more and 10% or less.

[0056] The second resin layer 12 contains an acid-modified polypropylene, but a layer containing an acid-modified polypropylene may be provided on the first resin layer 11 side, and a layer containing a polypropylene random copolymer without an acid-modified polypropylene as the main component may be provided on the third resin layer 13 side. By providing the layer on the first resin layer 11 side with an acid-modified polypropylene as the main component, adhesion to the first resin layer 11 is improved, and a layer without an acid-modified polypropylene is provided on the third resin layer 13 side, and is bonded to the third resin layer 13. This reduces the amount of acid-modified polypropylene used and reduces costs. The second resin layer 12 may have a thickness of 0.1 μm to 5 μm, and the thickness of the polypropylene layer without an acid-modified polypropylene may be 0.1 μm to 14.9 μm, resulting in a total thickness of 0.2 μm to 15 μm.

[0057] (Fourth Resin Layer) As shown in FIG. 2 , the polymer film 10 may include a fourth resin layer 14 on the side of the third resin layer 13 opposite the second resin layer 12. The fourth resin layer 14 includes a copolymer of propylene and an olefin other than propylene. Examples of the copolymer of propylene and an olefin other than propylene include polypropylene random copolymers. Polypropylene random copolymers are random copolymers of propylene and an olefin other than propylene (e.g., ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, etc.). Examples of random copolymers include ethylene-propylene random copolymers and ethylene-1-butene-propylene random copolymers. In addition to the copolymer of propylene and an olefin other than propylene, the fourth resin layer 14 may further include one or more selected from the group consisting of homopolypropylene, polypropylene block copolymer, and polyethylene. Among these, it is preferable that the fourth resin layer 14 further includes polyethylene, and it is more preferable that the fourth resin layer 14 further includes high-density polyethylene. The fourth resin layer 14 preferably contains 51% by mass or more of a copolymer of propylene and an olefin other than propylene, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 95% by mass or more. This provides sufficient impact resistance. The upper limit of the content of the copolymer of propylene and an olefin other than propylene in the fourth resin layer 14 is 100% by mass, and particularly preferably substantially 100% by mass. For example, the content of the copolymer of propylene and an olefin other than propylene in the fourth resin layer 14 is preferably 51% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 100% by mass or less, even more preferably 70% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less.

[0058] The thickness of the fourth resin layer 14 is preferably 0.2 μm or more, and more preferably 0.4 μm or more. This increases the drop impact resistance. The thickness of the fourth resin layer 14 is also preferably 15 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less. This improves the processability of the polymer film 10. For example, the thickness of the fourth resin layer 14 is preferably 0.2 μm or more and 15 μm or less, more preferably 0.4 μm or more and 5 μm or less, and even more preferably 0.4 μm or more and 2 μm or less.

[0059] The ratio of the thickness of the fourth resin layer 14 to the total thickness of the polymer film 10 is preferably 1% or more, and more preferably 2% or more. This can increase the drop impact resistance strength. Furthermore, the ratio of the thickness of the fourth resin layer 14 to the total thickness of the polymer film 10 is preferably 20% or less, and more preferably 10% or less. This can improve processability and impart sufficient rigidity to the polymer film 10. For example, the ratio of the thickness of the fourth resin layer 14 to the total thickness of the polymer film 10 is preferably 1% or more and 20% or less, and more preferably 2% or more and 10% or less.

[0060] 6, the polymer film 10 without the fourth resin layer 14 is laminated with a heat sealable heat sealant film 18 containing polypropylene on the vapor deposition film 15 side to form a laminate. The heat sealant film 18 of the obtained laminate is heat-sealed to form a packaging bag, which is then filled with contents and sealed.

[0061] A laminate may also be envisioned in which the polymer film 10, which includes the vapor-deposited film 15 but does not include the fourth resin layer 14, is sandwiched between two other films. In this case, a polypropylene base film 19 containing polypropylene is laminated on the vapor-deposited film 15 side, and a heat sealant film 18 containing polypropylene is laminated on the third resin layer 13 side to form a laminate. The heat sealant film 18 is heat-sealed to form a packaging bag, which is then filled with contents and sealed. This packaging bag may be ruptured by a drop impact.

[0062] 7, a laminate of three films can be prepared by laminating a polypropylene base film 19 containing polypropylene on the vapor-deposited film 15 side of a barrier film having a vapor-deposited film 15 on the first resin layer 11 side of a polymer film 10 provided with a fourth resin layer 14, and laminating a heat sealant film 18 containing polypropylene on the third resin layer 13 side. By using this laminate as a packaging material, it is possible to prevent the packaging bag produced from being broken by a drop impact.

[0063] When the third resin layer 13 is mainly composed of homopolypropylene, if the homopolymer has high crystallinity and is crystalline in layers, the homopolypropylene may undergo cohesive failure between the layered crystals upon impact. Polypropylene random copolymer has low crystallinity, and the polymers are entangled, so it is thought that cohesive failure due to impact is less likely to occur.

[0064] The polypropylene content in the polymer film 10 having the fourth resin layer 14 is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The polypropylene content in the polymer film 10 not having the fourth resin layer 14 is also preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. This improves the recyclability of the polymer film. The polypropylene may be any of homopolypropylene, polypropylene random copolymer, polypropylene block copolymer, and acid-modified products of these polypropylenes.

[0065] (Production of Polymer Film 10) The polymer film 10 is preferably a film that has been subjected to a stretching process. The stretching process may be uniaxial or biaxial. That is, the polymer film 10 may be a uniaxially stretched film or a biaxially stretched film. The biaxially stretched polymer film 10 can be produced, for example, by forming at least the first resin layer 11, the second resin layer 12, and the third resin layer 13 into a sheet by multilayer coextrusion and stretching the extruded sheet in the longitudinal direction (MD direction) and the transverse direction (TD direction). In the case of a polymer film 10 that further includes a fourth resin layer 14, the first resin layer 11, the second resin layer 12, the third resin layer 13, and the fourth resin layer 14 may be formed into a sheet by multilayer coextrusion and the extruded sheet may be stretched in the longitudinal direction and the transverse direction. Stretching in both directions is biaxial stretching, while stretching only in the longitudinal direction or the transverse direction is uniaxial stretching. Among these, biaxial stretching is preferred. The stretching ratio is preferably 2 times or more in both the longitudinal and transverse directions, more preferably 3 times or more, and even more preferably 5 times or more. This allows the strength and heat resistance of the polymer film 10 to be further improved. Furthermore, from the viewpoint of the breaking limit of the polypropylene film, the stretching ratio is preferably 15 times or less in both the longitudinal and transverse directions, more preferably 13 times or less, and even more preferably 10 times or less. The stretching ratio in the transverse direction is preferably greater than the stretching ratio in the longitudinal direction. For example, the stretching ratio in the longitudinal direction may be 3 times or more and 6 times or less, and the stretching ratio in the transverse direction may be 8 times or more and 13 times or less.

[0066] Biaxial stretching, which is one type of stretching process, may be simultaneous stretching in which stretching is performed simultaneously in the longitudinal and transverse directions, or may be sequential stretching in which stretching is performed in the longitudinal direction and then in the transverse direction. That is, the polymer film 10 may be a simultaneous biaxially stretched film or a sequentially biaxially stretched film. The polymer film 10 is preferably a sequentially biaxially stretched film, since it can be produced using a simple device, can be produced inexpensively, and has excellent productivity.

[0067] The resin layers may be formed by extruding the same or different resins using multiple extruders and then joining the extruded resins. The first resin layer 11 may be formed by extruding different polyamide resins as layers using multiple extruders, resulting in a multilayer structure. In the entire first resin layer 11 having a multilayer structure, it is sufficient that the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer and the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer are equal to or greater than a certain value.

[0068] As a biaxial stretching method, a method may be used in which at least the first resin layer 11, the second resin layer 12, and the third resin layer 13 are formed into a tubular film by multilayer co-extrusion, and the formed tube is stretched in the MD direction while being heated, and simultaneously stretched in the TD direction by supplying air into the tube.

[0069] Alternatively, the third resin layer 13 may be extruded, the resulting sheet stretched longitudinally, the first resin layer 11 and the second resin layer 12 co-extrusion laminated onto the uniaxially stretched third resin layer 13, and then stretched transversely. This simplifies the extrusion device and reduces the amount of work required for maintenance. Furthermore, by making the widths of the first resin layer 11 and the second resin layer laminated onto the third resin layer 13 narrower than that of the third resin layer 13, the first resin layer 11 is not included in the chucked portion during transverse stretching, and the recycled material from the chucked portion does not contain polyamide, thereby improving the recyclability of the recycled material.

[0070] The polymer film 10 is preferably stretched so that its tensile strength in the transverse direction (TD) is greater than its tensile strength in the longitudinal direction (MD). This configuration allows packaging bags made from the barrier film of the present disclosure to be highly tearable in one direction. The tensile strength of the polymer film 10 in the transverse direction (TD) is preferably 1.05 times or more, more preferably 1.1 times or more, and even more preferably 1.2 times or more, of the tensile strength in the longitudinal direction (MD). The tensile strength in the transverse direction (TD) can be, for example, 200 MPa or more and 300 MPa or less.

[0071] In this specification, the tensile strength of the polymer film 10 is measured in accordance with JIS K7127:1999. A tensile tester STA-1150 manufactured by Orientec Co., Ltd. can be used as a measuring instrument. A rectangular film 15 mm wide and 150 mm long cut from the polymer film 10 can be used as a test piece. The distance between the pair of chucks holding the test piece at the start of measurement is 100 mm, and the tensile speed is 300 mm / min. Unless otherwise specified in this specification, the environment during tensile strength measurement is a temperature of 23°C and a relative humidity of 50%.

[0072] The thickness of the polymer film 10 is preferably 10 μm or more. This improves the strength of the polymer film 10, making it less likely to break during processing. Furthermore, the thickness of the polymer film 10 is preferably 50 μm or less. This prevents the polymer film 10 from being stronger than required when used as a packaging material, and prevents waste of resources. For example, the thickness of the polymer film 10 is preferably 10 μm or more and 50 μm or less.

[0073] In the polymer film 10, it is preferable that the third resin layer 13 has the largest thickness among the first resin layer 11, the second resin layer 12, and the third resin layer 13, and that the thicknesses of the layers constituting the polymer film 10 satisfy the following formulas (1) and (2): Thickness of the first resin layer 11≦(Thickness of the polymer film 10) / 10 (1) Thickness of the second resin layer 12≦(Thickness of the polymer film 10) / 5 (2)

[0074] Since the third resin layer 13 containing homopolypropylene is the main component of the polymer film 10 and is the layer that determines the physical properties of the polymer film 10, it is preferable that the thickness of the third resin layer 13 be the maximum.

[0075] The polyamide resin contained in the first resin layer 11 is a resin different from polypropylene, and since a large amount of polyamide resin contained in the polymer film 10 may hinder recycling, it is preferable to reduce the amount of polyamide resin used. Therefore, the thickness of the first resin layer 11 is preferably 1 / 10 or less, and more preferably 1 / 13.3 or less, of the thickness of the polymer film 10.

[0076] The acid-modified polypropylene contained in the second resin layer 12 is a polypropylene-based resin and does not hinder recycling. However, because it is relatively expensive, it is preferable to use a small amount of acid-modified polypropylene as long as it can sufficiently bond the first resin layer 11 and the third resin layer 13 and absorb the stress caused by expansion and contraction of the third resin layer 13. Therefore, it is preferable that the thickness of the second resin layer 12 be ⅕ or less of the thickness of the polymer film 10.

[0077] In the polymer film 10, it is more preferable that the thickness of the first resin layer 11 constituting the polymer film 10 satisfies the following formula (3), and it is even more preferable that the thickness satisfies the following formula (4): (Thickness of polymer film 10) / 100≦Thickness of first resin layer 11 (3) (Thickness of polymer film 10) / 50≦Thickness of first resin layer 11 (4) When the thickness of the first resin layer 11 is equal to or greater than the lower limit, the high gas barrier property of the first resin layer 11 can improve the gas barrier property of the polymer film 10, and in addition, the adhesion with the vapor-deposited film 15 can be increased, further improving the gas barrier property.

[0078] In addition, in the polymer film 10, the thickness of the first resin layer 11 constituting the polymer film 10 preferably satisfies the following formula (5), and more preferably satisfies the following formula (6): (thickness of polymer film 10) / 100≦thickness of first resin layer 11≦(thickness of polymer film 10) / 10 (5) (thickness of polymer film 10) / 50≦thickness of first resin layer 11≦(thickness of polymer film 10) / 13.3 (6)

[0079] In the polymer film 10, it is more preferable that the thickness of the second resin layer 12 constituting the polymer film 10 satisfies the following formula (7): (thickness of polymer film 10) / 100≦thickness of second resin layer 12 (7) When the thickness of the second resin layer 12 is equal to or greater than the lower limit, the adhesion between the first resin layer 11 and the third resin layer 13 can be improved.

[0080] Furthermore, in the polymer film 10, it is preferable that the thickness of the second resin layer 12 constituting the polymer film 10 satisfies the following (8): (thickness of the polymer film 10) / 100≦thickness of the second resin layer 12≦(thickness of the polymer film 10) / 5 (8)

[0081] (Vapor-deposited film 15) As shown in FIG. 3 , the barrier film of the present disclosure includes a vapor-deposited film 15 containing an inorganic oxide on the first resin layer 11 side of the polymer film 10. Furthermore, when the polymer film 10 includes a fourth resin layer 14, the barrier film of the present disclosure includes a vapor-deposited film 15 containing an inorganic oxide on the first resin layer 11 side, as shown in FIG. 4 . The vapor-deposited film 15 may be formed on the surface of the first resin layer 11. Another layer may be provided between the first resin layer 11 and the vapor-deposited film 15. Forming the vapor-deposited film 15 can impart gas barrier properties, specifically oxygen barrier properties and water vapor barrier properties, to the barrier film. Furthermore, deterioration of the contents and the impact on the atmosphere can be suppressed, such as quality deterioration of the contents due to oxidation of the contents packaged in a packaging bag including a laminate produced using the barrier film of the present disclosure, deterioration of the contents due to evaporation or moisture absorption of water vapor, reduction in product value due to volatilization of aromatic components from the contents, and impact on the environment due to volatilization of aromatic components.

[0082] When a packaging bag made of a laminate including a barrier film with an aluminum vapor-deposited film is retorted, the aluminum vapor-deposited film dissolves from the edges, and the dissolved aluminum vapor-deposited film peels off. This phenomenon occurs particularly noticeably in shower retorts, in which hot water is sprayed onto the object to be sterilized. The adhesive strength between the polymer film and the vapor-deposited film decreases in the dissolved aluminum vapor-deposited film, causing the aluminum vapor-deposited film to peel off from the polymer film, resulting in a deterioration of the gas barrier properties. To prevent such problems from occurring, in the barrier film of the present disclosure, the vapor-deposited film 15 contains an inorganic oxide, preferably contains an inorganic oxide as a main component, and more preferably consists of an inorganic oxide.

[0083] Examples of inorganic oxides include aluminum oxide (alumina), silicon oxide (silica), magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, carbon-containing silicon oxide, etc. Among these, silicon oxide, carbon-containing silicon oxide, or aluminum oxide is preferred.

[0084] Aluminum oxide is aluminum oxide AlO ｘ (where x is a number of 0 or more and 1.5 or less) aluminum hydroxide oxide AlO ｙ (OH)ｚ (wherein y and z represent numbers satisfying 0≦y≦1.5, 0≦z≦3, and 2y+z=3) and aluminum hydroxide Al(OH) ３ It is okay to include.

[0085] The inorganic oxide is more preferably carbon-containing silicon oxide, since this can prevent the gas barrier properties from decreasing even after the barrier film is bent.

[0086] The thickness of the vapor-deposited film 15 is preferably 3 nm or more, more preferably 5 nm or more, and even more preferably 8 nm or more. This further improves the oxygen barrier property and water vapor barrier property of the barrier film. The thickness of the vapor-deposited film 15 is also preferably 150 nm or less, more preferably 60 nm or less, and even more preferably 40 nm or less. This prevents cracks from occurring in the vapor-deposited film 15. Furthermore, as long as the thickness of the vapor-deposited film 15 is within the above range, the recyclability of the barrier film when used as a constituent film for packaging materials is not impaired. For example, the thickness of the vapor-deposited film 15 is preferably 3 nm or more and 150 nm or less, more preferably 5 nm or more and 60 nm or less, and even more preferably 8 nm or more and 40 nm or less.

[0087] The deposition film 15 can be formed by a conventionally known method, such as a physical vapor deposition method (PVD method) including vacuum deposition, sputtering, and ion plating, and a chemical vapor deposition method (CVD method) including plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0088] The vapor-deposited film 15 may be a single layer formed by a single vapor deposition process, or may be a multilayer formed by multiple vapor deposition processes. In the case of a multilayer film, each layer may be made of the same material or different materials. Furthermore, each layer may be formed by the same method or different methods.

[0089] A vapor-deposited film 15 may be formed, and a layer containing an organic substance, such as the barrier coating layer 16 described below, may be provided on the outer surface of the vapor-deposited film 15. This provides high barrier properties. Alternatively, a vapor-deposited film may be provided on the surface of the layer containing an organic substance, and another layer containing an organic substance may be provided on the outer surface of the vapor-deposited film, thereby repeatedly laminating vapor-deposited films and layers containing an organic substance.

[0090] A plasma-assisted vacuum deposition apparatus can be used as an apparatus for forming a vapor-deposited film by the PVD method. Details of this deposition method are disclosed in Japanese Patent Application Laid-Open No. 2011-214089.

[0091] The plasma generating device used in the plasma chemical vapor deposition method can be a device that generates high-frequency plasma, pulsed wave plasma, microwave plasma, or the like. A device having two or more deposition chambers may also be used. Details of this deposition method are disclosed in JP 2012-076292 A.

[0092] A continuous vapor deposition film formation apparatus equipped with a plasma pretreatment chamber and a film formation chamber can be used as the apparatus used in the method for forming the vapor deposition film 15. In the plasma pretreatment chamber, plasma is irradiated from a plasma supply nozzle onto the first resin layer 11 of the polymer film 10. Next, in the film formation chamber, the vapor deposition film 15 is formed on the plasma-treated first resin layer 11. Details of this formation method are disclosed in WO 2019 / 087960.

[0093] It is preferable to perform plasma treatment on the surface of the vapor-deposited film 15. This can improve adhesion to a barrier coating layer 16 provided on the surface of the vapor-deposited film 15, which will be described later.

[0094] In the barrier film of the present disclosure, by using a carbon-containing silicon oxide vapor-deposited film as the vapor-deposited film 15, it is possible to suppress deterioration of the gas barrier property even after the barrier film is bent. The carbon-containing silicon oxide vapor-deposited film can be formed by a CVD method.

[0095] The carbon-containing silicon oxide vapor-deposited film contains silicon, oxygen, and carbon. In the carbon-containing silicon oxide vapor-deposited film, the carbon content is preferably 3% or more, more preferably 5% or more, and even more preferably 10% or more, relative to the total of the three elements silicon, oxygen, and carbon (100%). In the carbon-containing silicon oxide vapor-deposited film, the carbon content is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less, relative to the total of the three elements silicon, oxygen, and carbon (100%). For example, in the carbon-containing silicon oxide vapor-deposited film, the carbon content is preferably 3% or more and 50% or less, more preferably 5% or more and 40% or less, and even more preferably 10% or more and 35% or less, relative to the total of the three elements silicon, oxygen, and carbon (100%). By setting the carbon content in the above range in the carbon-containing silicon oxide vapor-deposited film, deterioration of the gas barrier property can be suppressed even after the barrier film is bent.

[0096] It is preferable that the carbon percentage is 3% or more and 50% or less, the oxygen percentage is 30% or more and 65% or less, and the silicon percentage is 25% or more and 40% or less, relative to the total of the three elements carbon, oxygen, and silicon (100%). By having a carbon percentage of 3% or more, deterioration in gas barrier properties can be further suppressed even after the barrier film is bent. By having a carbon percentage of 50% or less, the color of the appearance can be suppressed.

[0097] (Measurement of the Proportion of Each Element in Carbon-Containing Silicon Oxide Vapor Deposited Film) The proportions of carbon, silicon, and oxygen in the carbon-containing silicon oxide vapor deposited film can be measured by X-ray photoelectron spectroscopy (XPS) described below.

[0098] An X-ray photoelectron spectrometer (XPS) is used to measure the narrow spectrum of each element on the surface of the carbon-containing silicon oxide vapor-deposited film. The surface after measurement is then etched under the conditions described below to expose a new measurement surface. The exposed measurement surface is then subjected to narrow spectrum measurement for each element under the same conditions.

[0099] For each narrow spectrum of C1s, O1s, and Si2p, analysis software is used to subtract the background using the Shirley method to obtain the integrated intensity (area) of the peak of each element. The obtained integrated intensity (area) is used to calculate the proportion of each element (element %). In order to reduce the influence of surface contamination, the proportion of each element after one etching cycle of 30 seconds is used. <X-ray photoelectron spectrum measurement conditions> Apparatus: ESCA3400 manufactured by Shimadzu Corporation X-ray source: MgKα Emission current: 20 mA Acceleration voltage: 10 kV Resolution: Low Measurement area: Approximately 6 mmφ <Etching conditions> Ion species: Ar ＋ Ar gas introduction pressure: 2.0 × 10 －２ Pa Emission current: 30 mA Acceleration voltage: 0.3 kV Etching time: 30 seconds x 1 time

[0100] (Barrier Coat Layer 16) In one embodiment of the barrier film of the present disclosure, as shown in Fig. 5, a barrier coat layer 16 may be provided on the vapor-deposited film 15. By forming the barrier coat layer 16 on the surface of the vapor-deposited film 15, the oxygen barrier property and water vapor barrier property of the barrier film are further improved.

[0101] In one embodiment of the barrier film of the present disclosure, although not shown, when the polymer film 10 includes a fourth resin layer 14, a barrier coat layer 16 may be provided on the vapor-deposited film 15. By forming the barrier coat layer 16 on the surface of the vapor-deposited film 15, the oxygen barrier property and water vapor barrier property of the barrier film are further improved.

[0102] The barrier coat layer 16 contains a gas barrier resin such as ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol (PVA), polyester, polyurethane, or (meth)acrylic resin. Among these, polyvinyl alcohol is preferred from the viewpoint of improving oxygen barrier properties and water vapor barrier properties. By including polyvinyl alcohol in the barrier coat layer 16, the occurrence of cracks in the vapor-deposited film 15 can be effectively prevented.

[0103] The content of the gas barrier resin in the barrier coat layer 16 is preferably 50% by mass or more, and more preferably 75% by mass or more. This further improves the oxygen barrier property and water vapor barrier property. The content of the gas barrier resin in the barrier coat layer 16 is 100% by mass or less, preferably 95% by mass or less, and more preferably 90% by mass or less. For example, the content of the gas barrier resin in the barrier coat layer 16 is preferably 50% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 95% by mass or less, and even more preferably 75% by mass or more and 90% by mass or less.

[0104] The thickness of the barrier coat layer 16 is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. This further improves the oxygen barrier property and water vapor barrier property of the barrier film. Furthermore, the thickness of the barrier coat layer 16 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. This improves the processability of the barrier film. Furthermore, as long as the thickness of the barrier coat layer 16 is within the above range, recycling suitability is not impaired even when the barrier coat layer 16 is made of a material different from polypropylene. For example, the thickness of the barrier coat layer 16 is preferably 0.01 μm or more and 10 μm or less, more preferably 0.1 μm or more and 5 μm or less, and even more preferably 0.2 μm or more and 1 μm or less.

[0105] The barrier coat layer 16 can be formed by dissolving or dispersing the gas barrier resin in water or an appropriate solvent, applying the solution or dispersion, and drying it.

[0106] The barrier coat layer 16 is preferably a gas barrier coating film containing at least one resin composition, such as a hydrolyzate of a metal alkoxide or a hydrolysis condensate of a metal alkoxide, obtained by polycondensing a mixture of a metal alkoxide and a water-soluble polymer by a sol-gel method in the presence of a sol-gel catalyst, water, an organic solvent, etc. The gas barrier coating film is a gas barrier coating film of a mixture of a metal alkoxide and a water-soluble polymer, or a gas barrier coating film of a mixture of a metal alkoxide, a water-soluble polymer, and a silane coupling agent. By providing such a barrier coat layer 16 on the vapor-deposited film 15, the occurrence of cracks in the vapor-deposited film 15 can be effectively prevented.

[0107] The metal alkoxide is represented by the following general formula: １ ｎ M (OR ２ ) ｍ However, in the formula, R １ , R ２ each represents an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M.

[0108] Examples of the metal atom M include silicon, zirconium, titanium, and aluminum. １ and R ２ Examples of the organic group represented by the formula (I) include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and an i-butyl group.

[0109] Examples of metal alkoxides that satisfy the above general formula include tetramethoxysilane (Si(OCH ３ ) ４ ), tetraethoxysilane (Si(OC ２ H ５ ) ４ ), tetrapropoxysilane (Si(OC ３ H ７ ) ４ ), tetrabutoxysilane (Si(OC ４ H ９ ) ４ ) etc.

[0110] A silane coupling agent may be used together with the metal alkoxide. Examples of the silane coupling agent include known organic reactive group-containing organoalkoxysilanes, such as vinyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and 1,3,5-tris(3-methoxysilylpropyl)isocyanurate.

[0111] Two or more kinds of silane coupling agents may be used, and the silane coupling agent is preferably used in an amount of 1 part by mass to 20 parts by mass per 100 parts by mass of the total amount of the metal alkoxides.

[0112] As the water-soluble polymer, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferred, and from the viewpoints of oxygen barrier property, water vapor barrier property, water resistance and weather resistance, it is preferred to use these in combination.

[0113] The degree of polymerization of polyvinyl alcohol is preferably 300 or more. This can prevent deterioration of gas barrier properties due to bending. Furthermore, the degree of polymerization of polyvinyl alcohol is preferably 3000 or less. This can prevent processing from becoming difficult. For example, the degree of polymerization of polyvinyl alcohol is preferably 300 or more and 3000 or less.

[0114] The degree of saponification of polyvinyl alcohol is preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 99 mol % or more.

[0115] The degree of polymerization of the ethylene-vinyl alcohol copolymer is preferably 300 or more. This can prevent deterioration of gas barrier properties due to bending. Furthermore, the degree of polymerization of the ethylene-vinyl alcohol copolymer is preferably 3000 or less. This can prevent processing from becoming difficult. For example, the degree of polymerization of the ethylene-vinyl alcohol copolymer is preferably 300 or more and 3000 or less.

[0116] The saponification degree of the ethylene-vinyl alcohol copolymer is preferably 90 mol % or more, more preferably 95 mol % or more, and even more preferably 99 mol % or more.

[0117] The content of ethylene units in the ethylene-vinyl alcohol copolymer is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and particularly preferably 25 mol% or more. Furthermore, the content of ethylene units in the ethylene-vinyl alcohol copolymer is preferably 65 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less. For example, the content of ethylene units in the ethylene-vinyl alcohol copolymer is preferably 10 mol% or more and 65 mol% or less, more preferably 15 mol% or more and 55 mol% or less, even more preferably 20 mol% or more and 50 mol% or less, and even more preferably 25 mol% or more and 50 mol% or less. Ethylene-vinyl alcohol copolymers with different ethylene contents may be mixed.

[0118] The thickness of the gas barrier coating film is preferably 0.01 μm or more, more preferably 0.1 μm or more. This can improve the oxygen barrier property and water vapor barrier property of the barrier film and prevent cracks from occurring in the vapor-deposited film. Furthermore, the thickness of the gas barrier coating film is preferably 1 μm or less, more preferably 0.5 μm or less. This can prevent cracks from occurring in the gas barrier coating film itself while maintaining recyclability. For example, the thickness of the gas barrier coating film is preferably 0.01 μm or more and 1 μm or less, more preferably 0.1 μm or more and 0.5 μm or less.

[0119] The gas barrier coating film can be formed by applying a composition containing the above materials by a conventionally known means such as roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, applicator, etc., and polycondensing the composition by a sol-gel method. As a catalyst for the sol-gel method, an acid or an amine compound is preferred.

[0120] The composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butanol.

[0121] The method for forming a gas barrier coating film is described below. A metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent, etc. are mixed to prepare a composition. A polycondensation reaction gradually progresses within the composition. The composition is then applied to the vapor-deposited film 15 by the conventional method described above and dried. Upon drying, a polycondensation reaction progresses between the metal alkoxide and the water-soluble polymer, and, if the composition contains a silane coupling agent, also between the silane coupling agent, forming a composite polymer layer. The heating temperature during drying is preferably 20°C or higher, more preferably 50°C or higher, and even more preferably 80°C or higher, and is preferably 250°C or lower, more preferably 200°C or lower, and even more preferably 150°C or lower. For example, the heating temperature during drying is preferably 20°C or higher and 250°C or lower, more preferably 50°C or higher and 200°C or lower, and even more preferably 80°C or higher and 150°C or lower. The drying time is preferably 1 second to 10 minutes.

[0122] The barrier coating layer 16 may have a printed layer formed on its surface.

[0123] (Laminate) The barrier film of the present disclosure is made into a laminate by providing a barrier coat layer 16 on the surface of the vapor-deposited film 15 and laminating it with another film. As shown in Fig. 5 , a polymer film 10 having a first resin layer 11, a second resin layer 12, and a third resin layer 13 has a vapor-deposited film 15 on the first resin layer side of the barrier film, and the barrier coat layer 16 is provided on the surface of the vapor-deposited film 15 of the barrier film. It is also possible to laminate the surface of the vapor-deposited film 15 with another film without providing the barrier coat layer 16.

[0124] The barrier film of the present disclosure is formed into a laminate by providing a barrier coat layer 16 on the surface of the vapor-deposited film 15 and laminating it with another film. Although not shown, the barrier film has a vapor-deposited film 15 provided on the first resin layer 11 side of a polymer film 10 having a first resin layer 11, a second resin layer 12, a third resin layer 13, and a fourth resin layer 14, and the barrier coat layer 16 is provided on the surface of the vapor-deposited film 15 of the barrier film. It is also possible to laminate the vapor-deposited film 15 surface and another film without providing the barrier coat layer 16.

[0125] As shown in Figure 6, a heat sealant film 18 containing polypropylene is laminated to the barrier coat layer 16 side of the resulting barrier film having the barrier coat layer 16 via an adhesive layer 17 to form a laminate. The layer structure is polymer film 10 / vapor-deposited film 15 / barrier coat layer 16 / adhesive layer 17 / heat sealant film 18. A printed layer may be provided on the barrier coat layer 16 side. Alternatively, the heat sealant film 18 may be directly laminated to the barrier coat layer 16 side. In this case, the heat sealant film 18 is laminated without the adhesive layer 17.

[0126] When the barrier coat layer 16 is not provided, a heat sealant film 18 containing polypropylene is laminated on the vapor-deposited film side of the barrier film via an adhesive layer 17 to form a laminate. The layer structure is polymer film 10 / vapor-deposited film 15 / adhesive layer 17 / heat sealant film 18. Alternatively, the heat sealant film 18 may be directly laminated on the vapor-deposited film 15 side. In this case, the heat sealant film 18 is laminated without the adhesive layer 17 interposed therebetween.

[0127] Alternatively, a polypropylene substrate film 19 containing polypropylene may be laminated to the vapor-deposited film 15 side of the barrier film via an adhesive layer 17, and a heat-sealable heat sealant film 18 containing polypropylene may be laminated to the polypropylene substrate film 19 via the adhesive layer 17. The layer structure of the laminate is polymer film 10 / vapor-deposited film 15 / adhesive layer 17 / polypropylene substrate film 19 / adhesive layer 17 / heat sealant film 18. When a barrier coat layer 16 is provided on the vapor-deposited film 15 side, the structure is polymer film 10 / vapor-deposited film 15 / barrier coat layer 16 / adhesive layer 17 / polypropylene substrate film 19 / adhesive layer 17 / heat sealant film 18. A printed layer may be provided on the surface of the barrier coat layer on the vapor-deposited film 15 side. The polypropylene substrate film 19 may be a biaxially oriented polypropylene film. Alternatively, the heat sealant film 18 may be directly laminated to the polypropylene substrate film 19. In this case, the heat sealant film 18 is laminated without the adhesive layer 17.

[0128] As shown in Figure 2, a barrier coat layer 16 is provided on the surface of the vapor-deposited film 15 of a barrier film having a fourth resin layer 14 on a polymer film 10. As shown in Figure 7, a polypropylene base film 19 containing polypropylene is laminated on the barrier coat layer 16 side via an adhesive layer 17, and a heat sealant film 18 is laminated on the fourth resin layer 14 side via the adhesive layer 17 to form a laminate. The layer structure is polypropylene base film 19 / adhesive layer 17 / barrier coat layer 16 / vapor-deposited film 15 / polymer film 10 with fourth resin layer 14 / adhesive layer 17 / heat sealant film 18. When the barrier coat layer 16 is not provided, the polypropylene base film 19 containing polypropylene is laminated on the vapor-deposited film 15 side via the adhesive layer 17. The layer structure of the laminate is polypropylene base film 19 / adhesive layer 17 / vapor-deposited film 15 / polymer film 10 with fourth resin layer 14 / adhesive layer 17 / heat sealant film 18. In either case, the laminate includes a polypropylene base film 19 on the side of the barrier film opposite the heat sealant film 18. The polypropylene base film 19 may be a biaxially oriented polypropylene film. A printed layer may be provided on the polypropylene base film 19. The heat sealant film 18 may also be directly laminated to the fourth resin layer 14. In this case, the heat sealant film 18 is laminated without an adhesive layer 17 therebetween.

[0129] The heat sealant film 18 is primarily composed of polypropylene having a melting point of 120°C or higher, which improves the heat resistance of the packaging material. The polypropylene is not particularly limited as long as it has a melting point of 120°C or higher. In this specification, "polypropylene having a melting point of 120°C or higher" means polypropylene having a maximum peak temperature of 120°C or higher in DSC.

[0130] The heat sealant film 18 preferably contains polyethylene as a sealant material. By including polyethylene together with polypropylene, a sea-island structure can be formed in the heat sealant film 18. The "sea-island structure" refers to a structure in which polyethylene is discontinuously dispersed within a continuous region of polypropylene. When the heat sealant film 18 contains a sealant material other than polypropylene, the heat sealant film 18 is not limited to one having a sea-island structure, and may be one in which the two materials are compatible with each other.

[0131] The heat sealant film 18 preferably contains a sealant material having a melting point of 150°C or higher. General packaging bags for heat sterilization are filled with contents and then subjected to retort or boiling treatment, which may result in a deterioration in gas barrier properties and heat sealability. In the laminate of the present disclosure, the heat sealant film 18 contains polypropylene having a melting point of 150°C or higher, so that even if a packaging bag made from the laminate is subjected to a heat treatment such as retort or boiling, the deterioration in the gas barrier properties and heat sealability of the packaging bag can be effectively suppressed.

[0132] Retort processing is a process in which the contents are filled into a packaging bag for heat sterilization, sealed, and then the packaging bag for heat sterilization is heated under pressure using steam or heated hot water. Retort processing is classified into semi-retort processing and high-retort processing depending on the heating temperature. In semi-retort processing, for example, the contents are held for at least 3 minutes after the center of the contents reaches 121°C. In high-retort processing, for example, the contents are held for at least 3 minutes after the center of the contents reaches 135°C. Boiling processing is a process in which the contents are filled into a packaging bag for heat sterilization, sealed, and then the packaging bag for heat sterilization is heated without pressurization using steam or heated hot water. In boiling processing, for example, the contents are held for at least 3 minutes after the center of the contents reaches 90°C.

[0133] The polypropylene used in the heat sealant film 18 may be any of a homopolymer, a random copolymer, and a block copolymer. Among these, a block copolymer is preferred from the viewpoint of suitability for retort treatment and boiling treatment. The use of a block copolymer can improve the impact resistance of packaging bags produced using the barrier film of the present disclosure. For example, a propylene-ethylene block copolymer can be used as the block copolymer.

[0134] The adhesive used for the adhesive layer 17 may be either a one-component curing type, a two-component curing type, or a non-curing type. The adhesive may be either a solventless adhesive or a solvent-based adhesive, but from the viewpoint of environmental impact, it is preferable to use a solventless adhesive. Examples of solventless adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, and urethane-based adhesives, and among these, it is preferable to use a two-component curing urethane-based adhesive. The adhesive may be a combination of a modified polyolefin and a curing agent. By using an adhesive containing a modified polyolefin as the main component, it is possible to reduce the obstacles to recyclability caused by the adhesive.

[0135] The thickness of the adhesive layer 17 is not particularly limited, and can be, for example, 0.1 μm or more and 10 μm or less.

[0136] (Packaging Bag) A packaging bag can be produced by placing the heat sealant film 18 side of the laminate on the inner surface and heat sealing necessary portions of the heat sealant films 18. The packaging bag may be in any form, such as three-sided sealed, four-sided sealed, stand-up type, gusset type, pillow type, or type with a spout.

[0137] The produced packaging bag is filled with contents such as food, seasonings, beverages, supplements, medicines, enteral nutrients, pet food, etc., and then sealed. The sealed packaging bag is then subjected to a boiling treatment or a retort treatment. Some packaging bags are filled with heated contents before sealing. For example, the inner surface of the packaging bag is sterilized by filling it with contents heated to 80°C or higher.

[0138] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0139] The polyamides used in the following examples and comparative examples are as follows: Polyamide A: Polycondensation product of 1,6-hexanediamine and dicarboxylic acid in a molar ratio of isophthalic acid / terephthalic acid of 7 / 3. Polyamide B: Copolymer of 2-methyl-1,5-pentanediamine and dicarboxylic acid in a molar ratio of isophthalic acid / terephthalic acid of 7 / 3. Polyamide C: Polycondensation product of 2-methyl-1,5-pentanediamine and dicarboxylic acid in a molar ratio of isophthalic acid / terephthalic acid of 5 / 5. Polyamide D: Polycondensation product of metaxylenediamine and dicarboxylic acid in a molar ratio of adipic acid / isophthalic acid of 87 / 13. Polyamide E: Polycondensation product of metaxylenediamine and dicarboxylic acid in a molar ratio of adipic acid / isophthalic acid of 8 / 2. Polyamide F: Polycondensation product of metaxylenediamine and dicarboxylic acid in a molar ratio of adipic acid / isophthalic acid of 93 / 7. Polyamide G Polycondensation product of metaxylenediamine and adipic acid Polyamide H Polycondensation product of 1,6-hexanediamine and adipic acid

[0140] Example 1-1: A mixture of 20% by mass of polyamide A and 80% by mass of polyamide D was used as the resin (first resin) constituting the first resin layer. An acid-modified polypropylene random copolymer (ethylene-1-butene-propylene random copolymer graft-polymerized with 1.2 mol% maleic anhydride, MFR: 5.0) was used as the resin (second resin) constituting the second resin layer. Homopolypropylene (MFR: 3.0) was used as the resin (third resin) constituting the third resin layer. An ethylene-1-butene-propylene random copolymer (MFR: 5.3) was used as the resin (fourth resin) constituting the fourth resin layer. The first resin, second resin, third resin, and fourth resin were co-extruded and then stretched 5 times in the machine direction (MD direction) and 10 times in the transverse direction (TD direction) using a sequential biaxial stretching device to produce a polymer film of Example 1-1 comprising a first resin layer (0.7 μm), a second resin layer (1 μm), a third resin layer (17.0 μm), and a fourth resin layer (1.3 μm). The thickness of the polymer film of Example 1-1 was 20 μm. The polypropylene content of the entire polymer film of Example 1-1 was 95% by mass.

[0141] Example 1-2 A polymer film of Example 1-2 was produced in the same manner as in Example 1-1, except that a mixture of 22% by mass of polyamide A and 78% by mass of polyamide D was used as the first resin.

[0142] Example 1-3 A polymer film of Example 1-3 was produced in the same manner as in Example 1-1, except that a mixture of 20% by mass of polyamide A and 80% by mass of polyamide E was used as the first resin.

[0143] Example 1-4 A polymer film of Example 1-4 was produced in the same manner as in Example 1-1, except that a mixture of 18% by mass of polyamide A and 82% by mass of polyamide E was used as the first resin.

[0144] Comparative Example 1-1 A polymer film of Comparative Example 1-1 was produced in the same manner as in Example 1-1, except that a mixture of 20% by mass of polyamide A and 80% by mass of polyamide F was used as the first resin.

[0145] Comparative Example 1-2 A polymer film of Comparative Example 1-2 was produced in the same manner as in Example 1-1, except that a mixture of 20% by mass of polyamide B and 80% by mass of polyamide G was used as the first resin.

[0146] Comparative Example 1-3 A polymer film of Comparative Example 1-3 was produced in the same manner as in Example 1-1, except that a mixture of 20% by mass of polyamide C and 80% by mass of polyamide G was used as the first resin.

[0147] Comparative Example 1-4 A polymer film of Comparative Example 1-4 was produced in the same manner as in Example 1-1, except that a mixture of 20% by mass of polyamide A and 80% by mass of polyamide H was used as the first resin.

[0148] ( １ Measurement of H-NMR spectrum) The polymer films of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-4 were each shredded with scissors and placed in a sample vial. 6 mL of chloroform and 4 mL of formic acid were added to the sample vial and left to stand overnight. In this way, the first resin layer constituting the polymer film was dissolved in a mixed solvent of chloroform and formic acid. The organic solvent phase was filtered through a chromatodisc with a filter pore size of 0.45 μm, concentrated and dried using a nitrogen blowing device, and used as a measurement sample. 20 to 30 mg of the measurement sample was dissolved in deuterated chloroform (CDCl ３ The resulting solution was dissolved in a mixed solvent of 0.5 mL of acetic acid and 0.5 mL of formic acid, and transferred to an NMR sample tube. Measurement was performed using an NMR apparatus (AVANCE III HD 400 MHz, manufactured by Bruker Japan Co., Ltd.) under the following measurement conditions: １ H-NMR spectrum was measured. (Measurement conditions) Measurement nuclides: １ Measurement temperature: room temperature Number of scans: 32 Waiting time: 5 seconds Probe: PA BBO 400S1 BBF-H-D-05 Z SP Deuterated solvent: CDCl ３ (Internal standard: TMS) + formic acid Window function: exponential Spectral line width: 0.3 Hz Furthermore, 20 to 30 mg of each pellet of polyamide A to H was dissolved in deuterated chloroform (CDCl ３A standard sample was prepared by dissolving the standard sample in a mixed solvent of 0.5 mL of acetic acid and 0.5 mL of formic acid. １ The H-NMR spectrum was measured. １ The peaks derived from protons observed in the H-NMR spectrum were measured. １ The proton-derived peaks observed in the H-NMR spectrum measurement were assigned, and the proportion of the number of each diamine unit and the proportion of the number of each dicarboxylic acid unit were calculated from the area ratio of each peak, thereby calculating the proportion of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer, and the proportion of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer.

[0149] (Measurement of surface roughness Sa of first resin layer) The polymer films of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-4 were each placed in the chamber of an Ion Sputter device (Hitachi Science Systems, Ltd., E-1030) with the surface of the first resin layer facing the Pt-Pd target. After reducing the pressure, argon gas was introduced and adjusted to 10 Pa. A Pt-Pd layer was formed on the surface of the first resin layer for 60 seconds. Each formed polymer film was cut into 1.5 cm squares and fixed to a glass slide with tape so that the film-formed surface was opposite the glass slide. Next, the objective lens of a laser microscope (Keyence Corporation, measurement unit model number VK-X160, control unit model number VK-X150) was set to 50x magnification, 1x zoom, measurement quality ultra-high speed, pitch 0.13 μm, and no double scan. The field of view at this time was 203.555 μm × 271.495 μm. The polymer film fixed to the slide glass was placed under the objective lens so that the vertical direction (MD direction) and the short side direction of the field of view were parallel. A connection range of 1 in the short side direction × 5 in the long side direction was specified, and the upper and lower limit heights and brightness of the scan were manually set appropriately to obtain three connected images of five images connected in the horizontal direction (TD direction). The size of the connected images was 200 ± 5 μm × 1220 ± 10 μm. For each connected image, 0.5 mm was specified for waviness removal in surface shape correction to remove waviness. The entire area of ​​each connected image was specified for surface roughness measurement, and the surface roughness Sa was calculated. The average of the three calculated values ​​was taken as the surface roughness Sa of the first resin layer. The smaller the surface roughness Sa of the first resin layer, the smoother the surface of the first resin layer in the stretched polymer film, indicating that the resin constituting the first resin layer is suitable for film formation.

[0150] (Evaluation of Film Formability) The surface condition of each of the polymer films of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-4 was observed. The evaluation criteria were as follows: A: No resin breakage, holes, etc., good film formability. B: Resin breakage, holes, etc., poor film formability.

[0151] Table 1 shows the configurations, measurement results, and evaluation results of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-4.

[0152]

[0153] As is clear from Table 1 above, the polymer films of Examples 1-1 to 1-4, in which the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer and the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer were above a certain level, had a small surface roughness Sa of the first resin layer and were excellent in film formability.

[0154] Example 2-1 The polymer film of Example 1-1 was introduced into the unwinding compartment of a decompressible chamber having an unwinding compartment, a plasma treatment compartment, a film-forming compartment, a winding compartment, etc., and the chamber was decompressed. Using a plasma treatment device, the surface of the first resin layer of the polymer film was subjected to plasma pretreatment using a mixed gas of argon and oxygen at a volume ratio of 1:1 while applying tension to the polymer film in a roll-to-roll manner. In the continuously transported film-forming compartment, aluminum was vapor-deposited on the plasma-treated surface using a resistance heating method as an aluminum heating means while introducing oxygen, thereby forming a 10-nm-thick aluminum oxide (alumina) vapor-deposited film (PVD method).

[0155] Next, a barrier coating agent was prepared on the surface of the vapor-deposited film by the following procedure, and a barrier coating layer was formed. 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5 N hydrochloric acid were mixed to prepare a solution with a pH of 2.2. 175 g of tetraethoxysilane as a metal alkoxide was mixed with this solution while cooling to 10°C to obtain Solution A. 14.7 g of polyvinyl alcohol as a water-soluble polymer with a saponification degree of 99% or more and a degree of polymerization of 2400, 324 g of water, and 17 g of isopropyl alcohol were mixed to obtain Solution B. Solution A and Solution B were mixed in a mass ratio of 5.5:4.5 to obtain a barrier coating agent. The barrier coating agent was coated on the surface of the vapor-deposited film and dried. The thickness of the barrier coating layer formed by drying the barrier coating agent was 300 nm. In this manner, the barrier film of Example 2-1 was produced.

[0156] Example 2-2 A barrier film of Example 2-2 was produced in the same manner as in Example 2-1, except that the polymer film of Example 1-2 was used instead of the polymer film of Example 1-1.

[0157] Example 2-3 A barrier film of Example 2-3 was produced in the same manner as in Example 2-1, except that the polymer film of Example 1-3 was used instead of the polymer film of Example 1-1.

[0158] Example 2-4 A barrier film of Example 2-4 was produced in the same manner as in Example 2-1, except that the polymer film of Example 1-4 was used instead of the polymer film of Example 1-1.

[0159] Example 2-5 A barrier film of Example 2-5 was produced in the same manner as in Example 2-2, except for the following changes to the formation of the vapor-deposited film: The surface of the first resin layer of the polymer film of Example 1-2 was subjected to plasma pretreatment using a mixed gas of argon and oxygen at a volume ratio of 1:1. Silicon oxide was vapor-deposited on the plasma-treated surface using electron beam heating as heating means while introducing oxygen, to form a silicon oxide vapor-deposited film with a thickness of 30 nm (PVD method).

[0160] Example 2-6 A barrier film of Example 2-6 was produced in the same manner as in Example 2-5, except that the barrier coat layer was not formed.

[0161] Example 2-7 A barrier film of Example 2-7 was produced in the same manner as in Example 2-2, except that the formation of the vapor-deposited film was changed as follows. A carbon-containing silicon oxide vapor-deposited film having a thickness of 30 nm was formed on the surface of the first resin layer of the polymer film of Example 1-2 using a low-temperature plasma chemical vapor deposition apparatus in a roll-to-roll manner while applying tension to the polymer film (CVD method). The vapor-deposited film formation conditions were as follows: (Formation conditions) Hexamethyldisiloxane:oxygen gas:helium=1:10:10 (unit: slm) Power supplied to cooling / electrode drum: 22 kW Line speed: 40 m / min

[0162] Example 2-8 A barrier film of Example 2-8 was produced in the same manner as in Example 2-7, except that the barrier coat layer was not formed.

[0163] Comparative Example 2-1 A barrier film of Comparative Example 2-1 was produced in the same manner as in Example 2-1, except that the polymer film of Comparative Example 1-1 was used instead of the polymer film of Example 1-1.

[0164] Comparative Example 2-2 A barrier film of Comparative Example 2-2 was produced in the same manner as in Example 2-1, except that the polymer film of Comparative Example 1-2 was used instead of the polymer film of Example 1-1.

[0165] Comparative Example 2-3 A barrier film of Comparative Example 2-3 was produced in the same manner as in Example 2-1, except that the polymer film of Comparative Example 1-3 was used instead of the polymer film of Example 1-1.

[0166] Comparative Example 2-4 A barrier film of Comparative Example 2-4 was produced in the same manner as in Example 2-1, except that the polymer film of Comparative Example 1-4 was used instead of the polymer film of Example 1-1.

[0167] (Evaluation of Gas Barrier Properties of Barrier Films) The barrier films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4 were cut out to obtain test pieces. These test pieces were used to measure the oxygen permeability (unit: cc / (m ２ ·day·atm) and water vapor permeability (unit: g / (m ２ · day)) was measured by the following method. [Oxygen permeability] Using an oxygen permeability measuring device (OX-TRAN2 / 20, manufactured by MOCON Corporation), the polymer film side of the test piece was set so as to be the oxygen supply side, and the oxygen permeability was measured in accordance with JIS K 7126-2:2006 at a temperature of 23 ° C. and a relative humidity of 90% RH. [Water vapor permeability] Using a water vapor permeability measuring device (PERMATRAN-w 3 / 33, manufactured by MOCON Corporation), the polymer film side of the test piece was set so as to be the water vapor supply side, and the water vapor permeability was measured in accordance with JIS K 7129-2:2019 at a temperature of 40 ° C. and a relative humidity of 90% RH.

[0168] (Preparation of Laminate) A biaxially oriented polypropylene film with a thickness of 20 μm was prepared as the polypropylene base film. A urethane-based printing ink was applied to one side of the polypropylene base film by gravure roll coating to form a printed layer. The dried thickness of the printed layer was 1 μm. Hereinafter, the polypropylene base film with the printed layer formed thereon will be referred to as the printed film. The printed layer of the printed film and the surface of the barrier coat layer of the barrier film of Example 2-1 were bonded together using a two-component curing polyurethane adhesive. The thickness of the adhesive layer formed with the two-component curing polyurethane adhesive was 2 μm. Next, a 60 μm thick unstretched polypropylene film was prepared as the heat sealant film. The surface of the fourth resin layer of the barrier film of Example 2-1 was bonded to the heat sealant film using a two-component curing polyurethane adhesive. The thickness of the adhesive layer formed with the two-component curing polyurethane adhesive was 2 μm. In this manner, a laminate was prepared. Laminates were similarly produced using the barrier films of Examples 2-2 to 2-8 and Comparative Examples 2-1 to 2-4 instead of the barrier film of Example 2-1. Note that for the barrier films of Examples 2-6 and 2-8, which did not have a barrier coat layer, the printed layer was bonded to the vapor-deposited film surface of the barrier film instead of bonding the printed layer to the barrier coat layer surface of the barrier film.

[0169] (Evaluation of Gas Barrier Properties of Laminates) Test pieces were obtained by cutting out the laminates prepared from the barrier films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4. Using these test pieces, the oxygen permeability and water vapor permeability were measured in the same manner as described above.

[0170] (Evaluation of Gas Barrier Properties After Semi-Retort Treatment) Laminates prepared from the barrier films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4 were cut into A4 size, folded in half at the long edge, with the heat sealant film facing the film, and heat-sealed along three sides, including the fold, to a width of 7 mm to prepare three-sided sealed packaging bags. 200 mL of tap water was filled into this packaging bag, and the remaining side was heat-sealed to form a retort packaging bag filled with the contents. Using steam, the retort packaging bag was subjected to semi-retort treatment at 121°C and 0.2 MPa for 30 minutes. A laminate was cut out from the packaging bag after the semi-retort treatment, and the oxygen permeability and water vapor permeability were measured in the same manner as above.

[0171] (Evaluation of Gas Barrier Properties After High-Speed ​​Retort Treatment) Laminates prepared from the barrier films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4 were cut into A4 size, folded in half at the long edge, with the heat sealant film facing the film, and heat-sealed at 7 mm width along three sides, including the fold, to prepare three-sided sealed packaging bags. 200 mL of tap water was filled into this packaging bag, and the remaining side was heat-sealed to form a retort packaging bag filled with the contents. Using steam, the retort packaging bag was subjected to high-speed retort treatment at 135°C and 0.3 MPa for 30 minutes. A laminate was cut out from the packaging bag after high-speed retort treatment, and the oxygen permeability and water vapor permeability were measured in the same manner as described above.

[0172] (Evaluation of Gas Barrier Properties of Laminates after High Retort Treatment and Bending) Laminates prepared from the barrier films of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4 were cut into 320 mm x 440 mm pieces, folded in half along the long sides to face the heat sealant film, and heat-sealed three sides, including the fold, to a width of 7 mm to produce three-sided sealed packaging bags. This packaging bag was filled with 400 mL of tap water, and the remaining side was heat-sealed to seal the contents, forming a retort packaging bag. Using steam, the retort packaging bag was subjected to high retort treatment at 135°C and 0.3 MPa for 30 minutes. A 297 mm x 210 mm laminate was cut from the packaging bag after high retort treatment, and a bending load (stroke: 155 mm, bending motion: 440°) was applied 10 times using a Gelbo Flex Tester (manufactured by Tester Sangyo Co., Ltd.) in accordance with ASTM F 392. After the bending load, the oxygen permeability and water vapor permeability of the laminate were measured in the same manner as above.

[0173] The configurations and measurement results of Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4 are shown in Tables 2 and 3.

[0174]

[0175]

[0176] As is clear from Tables 2 and 3 above, the barrier films of Examples 2-1 to 2-8 and the laminates produced from those barrier films had lower oxygen permeabilities and water vapor permeabilities and were superior in gas barrier properties compared to the barrier films of Comparative Examples 2-1 to 2-4 and the laminates produced from those barrier films. Furthermore, the laminates produced from the barrier films of Examples 2-1 to 2-8 had lower oxygen permeabilities and water vapor permeabilities after semi-retort treatment, high-retort treatment, and high-retort treatment and flexion treatment compared to the laminates produced from the barrier films of Comparative Examples 2-1 to 2-4, and therefore were less susceptible to deterioration in gas barrier properties even when subjected to heat treatment and had excellent heat resistance.

[0177] 10: Polymer film 11: First resin layer 12: Second resin layer 13: Third resin layer 14: Fourth resin layer 15: Vapor deposition film 16: Barrier coating layer 17: Adhesive layer 18: Heat sealant film 19: Polypropylene base film

Claims

1. A polymer film comprising a first resin layer, a second resin layer, and a third resin layer in this order, wherein the first resin layer constitutes one of the outermost layers of the polymer film, the first resin layer comprises a polyamide resin, and the polyamide resin comprises a copolymerized polyamide which is a polycondensation product of diamine units and dicarboxylic acid units, the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 75 mol% or more, the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is 22 mol% or more, the second resin layer comprises an acid-modified polypropylene, and the third resin layer comprises homopolypropylene.

2. The polymer film according to claim 1, wherein the ratio of the number of aromatic diamine units to the total number of diamine units contained in the polyamide resin constituting the first resin layer is 75 mol % or more and 95 mol % or less.

3. A polymer film according to claim 1 or 2, wherein the ratio of the number of isophthalic acid units to the total number of dicarboxylic acid units contained in the polyamide resin constituting the first resin layer is 22 mol% or more and less than 45 mol%.

4. The polymer film according to claim 1 or 2, wherein the copolymer polyamide contained in the first resin layer is one type.

5. The polymer film according to claim 4, wherein the content of the copolyamide in the first resin layer is 70% by mass or more.

6. The polymer film according to claim 1 or 2, wherein the copolyamide contained in the first resin layer is a first copolyamide and a second copolyamide.

7. The polymer film according to claim 6, wherein the content of the first copolyamide in the first resin layer is 5% by mass or more and 24% by mass or less.

8. The polymer film according to claim 6, wherein the content of the second copolyamide in the first resin layer is 76% by mass or more and 95% by mass or less.

9. The polymer film according to claim 1 or 2, wherein the polypropylene content in the polymer film is 70% by mass or more.

10. The polymer film according to claim 1 or 2, wherein the third resin layer has the greatest thickness among the first, second and third resin layers, and the thicknesses of the layers constituting the polymer film satisfy the following formulas (1) and (2): Thickness of the first resin layer ≦ (thickness of the polymer film) / 10 (1) Thickness of the second resin layer ≦ (thickness of the polymer film) / 5 (2) 11. The polymer film according to claim 1 or 2, wherein the polymer film comprises a fourth resin layer on the opposite side of the third resin layer from the second resin layer, and the fourth resin layer contains a copolymer of propylene and an olefin other than propylene.

12. A barrier film comprising the polymer film according to claim 1 or 2 and a vapor-deposited film containing an inorganic oxide, the vapor-deposited film being provided on the first resin layer side.

13. The barrier film according to claim 12, which comprises a barrier coating layer on the vapor-deposited film side.

14. A laminate comprising the barrier film of claim 12 and a heat sealant film.

15. The laminate of claim 14, further comprising a polypropylene substrate film.

16. A packaging bag comprising the laminate according to claim 14.

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