Polymer film, barrier film, laminate, and packaging bag

Abstract

A polymer film 10 according to the present disclosure is characterized by comprising a first resin layer 11, a second resin layer 12, and a third resin layer 13 in this order, and is characterized in that: the first resin layer 11 constitutes one outermost layer of the polymer film 10; the first resin layer 11 contains a polyamide resin; a resin constituting the first resin layer 11 does not have a cold crystallization temperature; the resin constituting the first resin layer 11 has a glass transition temperature of 155°C or lower; the second resin layer 12 contains an acid-modified product of polypropylene; and the third resin layer 13 contains 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. However, some polyamides break when stretched after being formed into a film. There has been a demand for a polymer film that has film-forming properties that prevent breakage even when stretched.

[0011] Furthermore, some polymer films, which have a polyamide-containing layer on one side of a polypropylene film, tend to curl significantly when heated and sterilized. Therefore, there has been a demand for a polymer film that is less likely to curl even when heated.

[0012] Furthermore, when the 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.

[0013] Therefore, an object of the present disclosure is to provide a polymer film that is excellent in film-forming properties, heat resistance, and recyclability, and that can suppress interlayer delamination and can be used to produce a barrier film with excellent gas barrier properties. Another object of the present disclosure is to provide a barrier film, a laminate, and a packaging bag that use the polymer film.

[0014] The present inventors have found that by employing a polyamide-containing layer having a glass transition temperature below a certain level as a polyamide-containing layer on one side of a polypropylene film, the polyamide-containing layer does not break even when stretched at low temperatures, improving film formability. The present inventors have also found that by employing a layer having no observed cold crystallization temperature in differential scanning calorimetry (DSC) as a polyamide-containing layer on one side of a polypropylene film, the polyamide-containing layer does not crystallize when cooled after heating, making it less likely to shrink, thereby suppressing curling. Furthermore, the present inventors have noted that acid-modified polypropylene is a highly adhesive polypropylene-based resin, and have found that by providing a layer containing an acid-modified polypropylene between a polypropylene film and a polyamide-containing layer, interlayer delamination can be suppressed without impairing recyclability. The present disclosure has been completed based on these findings and through further investigation.

[0015] 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, the resin constituting the first resin layer does not have a cold crystallization temperature, and the resin constituting the first resin layer has a glass transition temperature of 155°C or lower, the second resin layer contains an acid-modified product of polypropylene, and the third resin layer contains homopolypropylene. <2> The polymer film according to <1>, wherein the first resin layer contains one type of polyamide resin. <3> The polymer film according to <2>, wherein the content of the polyamide resin in the first resin layer is 70% by mass or more. <4> The polymer film according to <1>, wherein the polyamide resin contained in the first resin layer is a first polyamide and a second polyamide, the first polyamide being an aromatic polyamide or an alicyclic polyamide, and the second polyamide being an aromatic polyamide, an alicyclic polyamide, or an aliphatic chain polyamide. <5> The polymer film according to <4>, wherein the content of the first polyamide in the first resin layer is 50% by mass or more and 95% by mass or less. <6> The polymer film according to <4> or <5>, wherein the content of the second polyamide in the first resin layer is 5% by mass or more and 50% by mass or less. <7> The polymer film according to any one of <1> to <6>, wherein the resin constituting the first resin layer does not have a melting point. <8> The polymer film according to any one of <1> to <7>, wherein the content of polypropylene in the polymer film is 70% by mass or more. <9> The polymer film according to any one of <1> to <8>, wherein the third resin layer has the largest thickness among the first resin layer, the second resin layer, and the third resin layer, and 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) <10> The polymer film according to any one of <1> to <9>, 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. <11> A barrier film comprising the polymer film according to any one of <1> to <10> and a vapor-deposited film containing an inorganic oxide, wherein the vapor-deposited film is provided on the first resin layer side. <12> The barrier film according to <11>, wherein a barrier coat layer is provided on the vapor-deposited film side. <13> A laminate comprising the barrier film according to <11> or <12> and a heat sealant film. <14> The laminate according to <13>, further comprising a polypropylene base film. <15> A packaging bag comprising the laminate according to <13> or <14>.

[0016] The present disclosure provides a polymer film that is excellent in film-forming properties, heat resistance, and recyclability, and that can suppress interlayer delamination and can be used to produce a barrier film with excellent gas barrier properties. The present disclosure also provides a barrier film, a laminate, and a packaging bag that use the polymer film.

[0017] 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.

[0018] 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.

[0019] (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.

[0020] 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.

[0021] As shown in FIG. 3, a vapor-deposited film 15 is provided on the first resin layer 11 side of the polymer film 10 of the present disclosure to serve as a barrier film.

[0022] Each layer included in the polymer film 10 of the present disclosure will be described below.

[0023] (First Resin Layer) The first resin layer contains a polyamide resin. The first resin layer may contain one or more polyamide resins. The content of the polyamide resin in the first resin layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more.

[0024] Below, we will explain raw material monomers from which structural units contained in polyamide resins can be derived, and then we will explain specific polyamide resins. Examples of raw material monomers include lactams, aminocarboxylic acids, diamines, and dicarboxylic acids. Polyamide resins can be obtained, for example, by ring-opening polymerization of lactams, polycondensation of aminocarboxylic acids, polycondensation of diamines and dicarboxylic acids, or combinations thereof.

[0025] Examples of lactams include γ-butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, undecanelactam, and dodecanelactam. Among these, ε-caprolactam, enantholactam, undecanelactam, and dodecanelactam are preferred. The number of carbon atoms in the lactam is, for example, 4 to 12.

[0026] Examples of aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Among these, 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid are preferred. The number of carbon atoms in the aminocarboxylic acid is, for example, 6 to 12.

[0027] Examples of diamines include aliphatic diamines such as aliphatic chain diamines and alicyclic diamines, and aromatic diamines. The aliphatic diamines have, for example, 2 to 20 carbon atoms, preferably 4 to 12 carbon atoms.

[0028] Examples of the aliphatic chain diamine include aliphatic linear diamines and aliphatic branched diamines, such as ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,5-pentanediamine, 2-methyl-1,8-octanediamine, and 2,2,4- / 2,4,4-trimethylhexamethylenediamine.

[0029] Examples of alicyclic diamines include 1,3- / 1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)propane, bis(3-methyl-4-aminocyclohexyl)methane, (3-methyl-4-aminocyclohexyl)propane, 1,3- / 1,4-bis(aminomethyl)cyclohexane, 5-amino-2,2,4-trimethyl-1-cyclopentanemethylamine, 5-amino-1,3,3-trimethylcyclohexanemethylamine, 4,4′-methylenebis(2-methylcyclohexylamine), norbornanedimethyleneamine, bis(aminomethyl)decalin, and bis(aminomethyl)tricyclodecane.

[0030] Among the aliphatic diamines, aliphatic chain diamines are preferred, aliphatic straight-chain diamines are more preferred, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine and dodecamethylenediamine are further preferred, and hexamethylenediamine is particularly preferred.

[0031] Examples of aromatic diamines include phenylenediamines such as p-phenylenediamine and m-phenylenediamine; xylylenediamines such as p-xylylenediamine and m-xylylenediamine; tolylenediamines such as 2,4-tolylenediamine and 2,6-tolylenediamine; diaminonaphthalenes such as 1,4-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene and 2,6-diaminonaphthalene; 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetramethyldiphenylmethane, diaminodiphenylmethane compounds such as phenylmethane, 4,4'-diamino-3,3',5,5'-tetraethyldiphenylmethane, and 4,4'-diamino-3,3'-dimethyl-5,5'-diethyldiphenylmethane; and bis(aminophenyl)propane compounds such as 2,2'-bis(3-aminophenyl)propane, 2,2'-bis(4-aminophenyl)propane, 2,2'-bis(4-amino-3-methylphenyl)propane, 2,2'-bis(4-amino-3-ethylphenyl)propane, 2,2'-bis(4-amino-3,5-dimethylphenyl)propane, 2,2'-bis(4-amino-3,5-diethylphenyl)propane, and 2,2'-bis(4-amino-3-methyl-5-ethylphenyl)propane.

[0032] Among aromatic diamines, xylylenediamine is preferred, p-xylylenediamine and m-xylylenediamine are more preferred, and m-xylylenediamine is even more preferred.

[0033] Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as aliphatic chain dicarboxylic acids and alicyclic dicarboxylic acids, and aromatic dicarboxylic acids. The aliphatic dicarboxylic acids have, for example, 2 to 20 carbon atoms, preferably 6 to 12 carbon atoms.

[0034] Examples of the aliphatic chain dicarboxylic acid include aliphatic linear dicarboxylic acids and aliphatic branched dicarboxylic acids, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosane dioic acid.

[0035] Alicyclic dicarboxylic acids include, for example, 1,3- / 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid.

[0036] Among the aliphatic dicarboxylic acids, aliphatic chain dicarboxylic acids are preferred, aliphatic straight-chain dicarboxylic acids are more preferred, adipic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid are further preferred, and adipic acid is particularly preferred.

[0037] Examples of aromatic dicarboxylic acids include phthalic acid compounds such as isophthalic acid, terephthalic acid, and orthophthalic acid; 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; 4,4'-biphenyldicarboxylic acid; and diphenylmethane dicarboxylic acids such as diphenylmethane-2,4-dicarboxylic acid, diphenylmethane-3,3'-dicarboxylic acid, diphenylmethane-3,4'-dicarboxylic acid, and diphenylmethane-4,4'-dicarboxylic acid.

[0038] Among the aromatic dicarboxylic acids, phthalic acid compounds are preferred, with isophthalic acid and terephthalic acid being more preferred.

[0039] Examples of polyamide resins include aliphatic polyamides and aromatic polyamides.

[0040] The aliphatic polyamide may be a polyamide resin composed of one type of lactam or one type of aminocarboxylic acid. The aliphatic polyamide may be a polyamide resin composed of two or more monomers selected from lactams and aminocarboxylic acids. The aliphatic polyamide may be a polyamide resin composed of a combination of one or more aliphatic diamines and one or more aliphatic dicarboxylic acids. The aliphatic polyamide may be a polyamide resin composed of a combination of lactam and / or aminocarboxylic acid, aliphatic diamine, and aliphatic dicarboxylic acid.

[0041] The aliphatic polyamide may be an aliphatic chain polyamide having no cyclic structure in the molecule, or an alicyclic polyamide having a cyclic structure in the molecule.

[0042] In the following examples, polyamide is also referred to as "PA." Specific examples of aliphatic linear polyamides include polycaprolactam (PA6), polyenantholactam (PA7), polyundecane lactam (PA11), polylauryllactam (PA12), polyhexamethylene adipamide (PA66), polytetramethylene dodecamide (PA412), polypentamethylene azelamide (PA59), polypentamethylene sebacamide (PA510), polypentamethylene dodecamide (PA512), polyhexamethylene azelamide (PA69), and polyhexamethylene sebacamide (PA61). 0), polyhexamethylene dodecamide (PA612), polynonamethylene adipamide (PA96), polynonamethylene azelamide (PA99), polynonamethylene sebacamide (PA910), polynonamethylene dodecamide (PA912), polydecamethylene adipamide (PA106), polydecamethylene azelamide (PA109), polydecamethylene decamide (PA1010), polydecamethylene dodecamide (PA1012), polydodecamethylene adipamide (PA126), polydodecamethylene azelamide (PA129), Polydodecamethylene sebacamide (PA1210), Polydodecamethylene dodecamide (PA1212), Caprolactam / Hexamethylenediaminoadipic acid copolymer (PA6 / 66), Caprolactam / Hexamethylenediaminoazelaic acid copolymer (PA6 / 69), Caprolactam / Hexamethylenediaminosebacic acid copolymer (PA6 / 610), Caprolactam / Hexamethylenediaminoundecanoic acid copolymer (PA6 / 611), Caprolactam / Hexamethylenediaminododecanoic acid copolymer (PA6 / 612) , caprolactam / aminoundecanoic acid copolymer (PA6 / 11), caprolactam / lauryllactam copolymer (PA6 / 12), caprolactam / hexamethylenediaminoadipic acid / lauryllactam copolymer (PA6 / 66 / 12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid copolymer (PA6 / 66 / 610), and caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminododecanedicarboxylic acid copolymer (PA6 / 66 / 612).Examples of the alicyclic polyamide include a copolymer of 4,4'-methylenebis(2-methylcyclohexylamine) and dodecanedioic acid (PA MACM12), a copolymer of 4,4'-methylenebis(2-methylcyclohexylamine), 4,4'-methylenebis(cyclohexylamine), and dodecanedioic acid (PA MACM12 / PACM12), a copolymer of 4,4'-methylenebis(2-methylcyclohexylamine), isophthalic acid, and dodecanedioic acid (PA MACMI / 12), a copolymer of 4,4'-methylenebis(2-methylcyclohexylamine), isophthalic acid, terephthalic acid, and dodecanedioic acid (PA MACMI / MACMT / 12), and a copolymer of 4,4'-methylenebis(2-methylcyclohexylamine) and tetradecanedioic acid (PA MACM14).

[0043] As the aliphatic polyamide, from the viewpoint of improving physical properties such as abrasion resistance, cold resistance, impact resistance, and oil resistance, crystalline aliphatic polyamides such as PA6, PA11, PA12, PA66, PA610, PA612, PA6 / 66, and PA6 / 66 / 12 are preferred.

[0044] The melting point of the crystalline aliphatic polyamide is preferably 170°C or higher, more preferably 180°C or higher. The melting point of the crystalline aliphatic polyamide is preferably 300°C or lower, more preferably 250°C or lower, even more preferably 230°C or lower, even more preferably 220°C or lower, and particularly preferably 215°C or lower or 210°C or lower. In the present disclosure, the melting point is obtained by differential scanning calorimetry (DSC) described below. If the melting point is low, for example, when polypropylene and a crystalline aliphatic polyamide are co-extruded to form a co-extruded resin film, the difference in melting points between the polypropylene and the crystalline aliphatic polyamide is small, thereby improving moldability. For example, the melting point of the crystalline aliphatic polyamide is preferably 170°C or higher and 300°C or lower, more preferably 170°C or higher and 250°C or lower, even more preferably 170°C or higher and 230°C or lower, still more preferably 170°C or higher and 220°C or lower, and particularly preferably 180°C or higher and 215°C or lower, or 180°C or higher and 210°C or lower.

[0045] The aromatic polyamide is a polyamide resin having structural units derived from an aromatic diamine and structural units derived from an aliphatic dicarboxylic acid, a polyamide resin having structural units derived from an aliphatic diamine and structural units derived from an aromatic dicarboxylic acid, or a polyamide resin having structural units derived from an aromatic diamine and structural units derived from an aromatic dicarboxylic acid. Examples include polyamide resins composed of an aromatic diamine and an aliphatic dicarboxylic acid, polyamide resins composed of an aliphatic diamine and an aromatic dicarboxylic acid, and polyamide resins composed of an aromatic diamine and an aromatic dicarboxylic acid.

[0046] In an aromatic polyamide composed of an aromatic diamine and an aliphatic dicarboxylic acid, the diamines do not all need to be aromatic diamines, and may further contain structural units derived from an aliphatic diamine. In an aromatic polyamide composed of an aliphatic diamine and an aromatic dicarboxylic acid, the dicarboxylic acids do not all need to be aromatic dicarboxylic acids, and may further contain structural units derived from an aliphatic dicarboxylic acid. In a polyamide resin having structural units derived from an aromatic diamine and structural units derived from an aromatic dicarboxylic acid, the diamines do not all need to be aromatic diamines, and may further contain structural units derived from an aliphatic diamine. In a polyamide resin having structural units derived from an aromatic diamine and structural units derived from an aromatic dicarboxylic acid, the dicarboxylic acids do not all need to be aromatic dicarboxylic acids, and may further contain structural units derived from an aliphatic dicarboxylic acid. These aromatic polyamides may further contain structural units derived from a lactam and / or an aminocarboxylic acid.

[0047] Specific examples of aromatic polyamides include polyhexamethylene terephthalamide (PA6T), polyhexamethylene isophthalamide (PA6I), polynonamethylene terephthalamide (PA9T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (PA66 / 6I), polyhexamethylene terephthalamide / polycaproamide copolymer (PA6T / 6), polyhexamethylene isophthalamide / polycaproamide copolymer (PA6I / 6), polyhexamethylene terephthalamide / polydodecaamide copolymer (PA6T / 12), polyhexamethylene isophthalamide, and polyhexamethylene isophthalamide copolymer (PA6T / 12). polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA6I / 6T), polyhexamethylene terephthalamide / poly(2-methylpentamethylene terephthalamide) copolymer (PA6T / M5T), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (PA66 / 6T / 6I), polyhexamethylene adipamide / polycaproamide / polyhexamethylene isophthalamide copolymer (PA66 / 6 / 6I), polymetaxylylene adipamide (PAMXD6), polymetaxylylene isophthalamide (PAMXDI), and polymetaxylylene adipamide / polymetaxylylene isophthalamide copolymer (PAMXD6I). Among these, PA6I / 6T, PAMXD6, PAMXDI and PAMXD6I are preferred, and PA6I / 6T is more preferred.

[0048] Aromatic polyamides are preferred as gas barrier resins. The aromatic polyamides may be amorphous aromatic polyamides such as PA6I / 6T, or crystalline aromatic polyamides such as PA6T, PA9T, PA6I, and PAMXD6. Among these, amorphous aromatic polyamides are preferred from the viewpoints of gas barrier properties and transparency.

[0049] Specific examples of amorphous aromatic polyamides include copolymers of hexamethylenediamine and isophthalic acid, copolymers of m-xylylenediamine and isophthalic acid, copolymers of hexamethylenediamine and dicarboxylic acid in which the molar ratio of isophthalic acid / terephthalic acid is 7 / 3, copolymers of 1,6-hexanediamine and dicarboxylic acid in which the molar ratio of isophthalic acid / terephthalic acid is 1 / 1, copolymers of m-xylylenediamine and dicarboxylic acid in which the molar ratio of adipic acid / isophthalic acid is 1 / 1, copolymers of 2-methyl-1,5-pentanediamine and dicarboxylic acid in which the molar ratio of isophthalic acid / terephthalic acid is 7 / 3, and copolymers of 2,2,4-trimethylhexamethylenediamine and terephthalic acid (PANDT / INDT).

[0050] Specific examples of the crystalline aromatic polyamide include a copolymer of m-xylylenediamine and adipic acid, a copolymer of m-xylylenediamine and a dicarboxylic acid in which the molar ratio of adipic acid / isophthalic acid is 93 / 7, and a copolymer of m-xylylenediamine and a dicarboxylic acid in which the molar ratio of adipic acid / isophthalic acid is 8 / 2.

[0051] The amorphous polyamide means a polyamide that does not have a clear melting point, specifically, a polyamide having a crystalline melting enthalpy ΔHm of 5 J / g or less, preferably 3 J / g or less, and more preferably 1 J / g or less. The crystalline melting enthalpy is measured by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012 and JIS K 7122:2012.

[0052] As the amorphous aromatic polyamide, an aromatic polyamide having two or more constituent units derived from an aromatic dicarboxylic acid is preferred, and a polyamide having, as the dicarboxylic acid component, constituent units derived from isophthalic acid and constituent units derived from terephthalic acid, and as the diamine component, constituent units derived from an aliphatic diamine (hereinafter also referred to as "polyamide (a)") is more preferred.

[0053] In polyamide (a), the proportion of isophthalic acid-derived structural units in 100 mol% of dicarboxylic acid-derived structural units is preferably 40 mol% or more, more preferably 50 mol% or more. In polyamide (a), the proportion of isophthalic acid-derived structural units in 100 mol% of dicarboxylic acid-derived structural units is preferably 98 mol% or less, more preferably 80 mol% or less. For example, in polyamide (a), the proportion of isophthalic acid-derived structural units in 100 mol% of dicarboxylic acid-derived structural units is preferably 40 mol% or more and 98 mol% or less, more preferably 50 mol% or more and 80 mol% or less. In polyamide (a), the proportion of terephthalic acid-derived structural units in 100 mol% of dicarboxylic acid-derived structural units is preferably 2 mol% or more, more preferably 20 mol% or more. In polyamide (a), the proportion of terephthalic acid-derived structural units in 100 mol% of dicarboxylic acid-derived structural units is preferably 60 mol% or less, more preferably 50 mol% or less. For example, in the polyamide (a), the proportion of the structural units derived from terephthalic acid in 100 mol % of the structural units derived from dicarboxylic acids is preferably 2 mol % or more and 60 mol % or less, more preferably 20 mol % or more and 50 mol % or less. The proportion can be measured by NMR.

[0054] In the polyamide (a), the total proportion of the structural units derived from isophthalic acid and the structural units derived from terephthalic acid, relative to 100 mol% of the structural units derived from dicarboxylic acids, is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more, 95 mol% or more, or 98 mol% or more. The polyamide (a) may, if necessary, contain structural units derived from dicarboxylic acids other than isophthalic acid and terephthalic acid (e.g., adipic acid).

[0055] The polyamide (a) preferably has a structural unit derived from hexamethylenediamine as a diamine component. In the polyamide (a), the proportion of the structural unit derived from hexamethylenediamine in 100 mol% of the structural units derived from diamine is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, particularly preferably 90 mol% or more, 95 mol% or more, or 98 mol% or more. The polyamide (a) may have a structural unit derived from a diamine other than hexamethylenediamine, if necessary. The polyamide (a) is preferably PA6I / 6T.

[0056] The glass transition temperature of the amorphous aromatic polyamide is, for example, 90° C. or higher, preferably 95° C. or higher, and more preferably 100° C. or higher. The glass transition temperature of the amorphous aromatic polyamide is, for example, 180° C. or lower, preferably 160° C. or lower, and more preferably 150° C. or lower. The glass transition temperature of the amorphous aromatic polyamide is, for example, 90° C. or higher and 180° C. or lower, preferably 95° C. or higher and 160° C. or lower, and more preferably 100° C. or higher and 150° C. or lower. The glass transition temperature can be obtained by differential scanning calorimetry (DSC) described below.

[0057] In one embodiment, the first resin layer contains one type of polyamide resin. When the first resin layer contains one type of polyamide resin, the content of the polyamide resin 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. When the first resin layer contains one type of polyamide resin, the upper limit of the content of the polyamide resin in the first resin layer is 100% by mass.

[0058] When the first resin layer contains only one type of polyamide resin, the polyamide resin is preferably an amorphous polyamide, more preferably an amorphous aromatic polyamide. Specific examples of the amorphous polyamide and amorphous aromatic polyamide are as described above.

[0059] In one embodiment, the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide. When the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the first polyamide is an aromatic polyamide or an alicyclic polyamide. When the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the second polyamide is an aromatic polyamide, an alicyclic polyamide, or an aliphatic linear polyamide. In one embodiment, the first polyamide is an aromatic polyamide, and the second polyamide is an aromatic polyamide. In one embodiment, the first polyamide is an aromatic polyamide, and the second polyamide is an alicyclic polyamide. In one embodiment, the first polyamide is an aromatic polyamide, and the second polyamide is an aliphatic linear polyamide. In one embodiment, the first polyamide is an alicyclic polyamide, and the second polyamide is an aromatic polyamide. In one embodiment, the first polyamide is an alicyclic polyamide, and the second polyamide is an aromatic polyamide. In one embodiment, the first polyamide is an alicyclic polyamide, and the second polyamide is an aromatic polyamide. In one embodiment, the first polyamide is an alicyclic polyamide and the second polyamide is an aliphatic linear polyamide. Specific examples of aromatic polyamides, alicyclic polyamides, and aliphatic linear polyamides are as described above.

[0060] When the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the content of the first polyamide in the first resin layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more. When the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the content of the first polyamide in the first resin layer is preferably 95% by mass or less, more preferably 92% by mass or less, and even more preferably 90% by mass or less. For example, when the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the content of the first polyamide in the first resin layer is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 92% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less. When the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the content of the second polyamide in the first resin layer is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. When the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the content of the second polyamide in the first resin layer is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less. For example, when the polyamide resin contained in the first resin layer is two types, a first polyamide and a second polyamide, the content of the second polyamide in the first resin layer is preferably 5% by mass or more and 50% by mass or less, more preferably 8% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less.

[0061] In the present disclosure, the glass transition temperature of the resin constituting the first resin layer 11 is 155°C or lower, preferably 130°C or lower, and more preferably 115°C or lower. In the present disclosure, the glass transition temperature of the resin constituting the first resin layer 11 is preferably 60°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher. A barrier film produced from a polymer film including such a first resin layer 11 has, for example, excellent gas barrier properties. For example, the glass transition temperature of the resin constituting the first resin layer 11 is preferably 60°C or higher and 155°C or lower, more preferably 90°C or higher and 130°C or lower, and even more preferably 100°C or higher and 115°C or lower. The glass transition temperature of the resin constituting the first resin layer 11 refers to the glass transition temperature of the resin when the first resin layer 11 is made of one type of resin, or refers to the glass transition temperature of a resin composition containing two or more resins when the first resin layer 11 is made of two or more types of resins. When the resin constituting the first resin layer 11 does not have a glass transition temperature, it does not fall under the polymer film 10 of the present disclosure. The glass transition temperature of the resin constituting the first resin layer 11 can be obtained by differential scanning calorimetry (DSC) described below.

[0062] The glass transition temperature of the resin constituting the first resin layer 11 can be adjusted by appropriately adjusting the types and proportions of monomers used in synthesizing the polyamide resin. Furthermore, when the first resin layer contains two or more types of polyamide resins, the glass transition temperature of the resin constituting the first resin layer 11 can also be adjusted by mixing the two or more types of polyamide resins in an appropriate proportion. For example, increasing the content of amorphous polyamide in the first resin layer 11 tends to increase the glass transition temperature of the resin constituting the first resin layer 11.

[0063] In the present disclosure, the resin constituting the first resin layer 11 does not have a cold crystallization temperature. Since the resin constituting the first resin layer 11 does not have a cold crystallization temperature, shrinkage due to crystallization is less likely to occur in the first resin layer, and cracks are less likely to occur in the vapor-deposited film 15 in contact with the first resin layer 11. As a result, a barrier film produced using the polymer film 10 has excellent gas barrier properties. The cold crystallization temperature of the resin constituting the first resin layer 11 refers to the cold crystallization temperature of the resin when the first resin layer 11 contains only one type of resin, or refers to the cold crystallization temperature of a resin composition containing two or more types of resins when the first resin layer 11 contains two or more types of resins. The cold crystallization temperature of the resin constituting the first resin layer 11 can also be obtained by differential scanning calorimetry (DSC), as described below.

[0064] By appropriately adjusting the types and proportions of monomers used in synthesizing the polyamide resin, it is possible to form the first resin layer 11 composed of a resin that does not have a cold crystallization temperature. Furthermore, when the first resin layer contains two or more types of polyamide resins, it is also possible to form the first resin layer 11 composed of a resin that does not have a cold crystallization temperature by mixing the two or more types of polyamide resins in an appropriate proportion. For example, if the content of amorphous polyamide in the first resin layer 11 is increased, the resin that constitutes the first resin layer 11 tends to lose its cold crystallization temperature.

[0065] In the present disclosure, the resin constituting the first resin layer 11 may or may not have a melting point, but preferably does not have a melting point. A polymer film 10 in which the resin constituting the first resin layer 11 does not have a melting point has, for example, excellent film-forming properties. The melting point of the resin constituting the first resin layer 11 refers to the melting point of the resin when the first resin layer 11 is made of one type of resin, or refers to the melting point of a resin composition containing two or more types of resins when the first resin layer 11 is made of two or more types of resins. The melting point of the resin constituting the first resin layer 11 can also be obtained by differential scanning calorimetry (DSC) as described below.

[0066] In the present disclosure, when the resin constituting the first resin layer 11 has a melting point, the melting point of the resin constituting the first resin layer 11 is preferably 170°C or higher, more preferably 180°C or higher, and even more preferably 185°C or higher. In the present disclosure, when the resin constituting the first resin layer 11 has a melting point, the melting point of the resin constituting the first resin layer 11 is preferably 240°C or lower, more preferably 200°C or lower, and even more preferably 190°C or lower. A barrier film made from a polymer film including such a first resin layer 11 has, for example, excellent gas barrier properties. For example, when the resin constituting the first resin layer 11 has a melting point, the melting point of the resin constituting the first resin layer 11 is preferably 170°C or higher and 240°C or lower, more preferably 180°C or higher and 200°C or lower, and even more preferably 185°C or higher and 190°C or lower.

[0067] By appropriately adjusting the types and proportions of monomers used in synthesizing the polyamide resin, it is possible to form the first resin layer 11 composed of a resin that does not have a cold crystallization temperature, or a first resin layer 11 composed of a resin having the above-mentioned melting point. Furthermore, when the first resin layer contains two or more types of polyamide resins, it is also possible to form the first resin layer 11 composed of a resin that does not have a cold crystallization temperature, or a first resin layer 11 composed of a resin having the above-mentioned melting point, by mixing two or more types of polyamide resins in an appropriate ratio. For example, if the content of amorphous polyamide in the first resin layer 11 is increased, the resin that constitutes the first resin layer 11 tends to lose its melting point.

[0068] Next, a detailed description will be given of a differential scanning calorimetry (DSC) measurement method, which is a method for determining the glass transition temperature, cold crystallization temperature, and melting point of the resin constituting the first resin layer 11.

[0069] A sample is prepared by scraping off the surface of the first resin layer 11 of the substrate film 10 shown in FIG. 1 or 2 , the barrier film shown in FIG. 3 , 4 , or 5 , or the laminated laminate shown in FIG. 6 or 7 with a commercially available scalpel or single-edged blade. In the case of the laminate shown in FIG. 6 or 7 , the surface of the first resin layer 11 is peeled off with a solvent or the like to expose it, and then scraped off with a commercially available scalpel or single-edged blade. Approximately 1 mg of the sample is packed into an aluminum pan, and differential scanning calorimetry (DSC), including heat flux differential scanning calorimetry (heat flux DSC), is performed using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name: DSC7000X) as follows. The sample is held at 20°C for 5 minutes, then heated from 20°C to 300°C at a heating rate of 20°C / min (first heating), and held at 300°C for 5 minutes. Next, the temperature is decreased from 300°C to 20°C at a rate of 20°C / min (first temperature decrease) and held at 20°C for 5 minutes. Then, the temperature is increased from 20°C to 300°C at a rate of 20°C / min (second temperature increase) and held at 300°C for 5 minutes. Indium is used for temperature calibration, and the flow rate of nitrogen gas is 20 mL / min.

[0070] The melting peak temperature (Tpm) is determined from the DSC curve obtained in the first heating, and is taken as the melting point of the resin constituting the first resin layer 11. However, since the melting peaks from 155°C or higher and lower than 165°C are melting peaks of polypropylene derived from the second resin layer 12 or the third resin layer 13 scraped off together with the first resin layer 11, the melting peak temperatures (Tpm) from 155°C or higher and lower than 165°C are not taken as the melting peak temperatures of the resin constituting the first resin layer 11. If no melting peak is observed in the DSC curve obtained in the first heating, it is determined that the resin constituting the first resin layer 11 does not have a melting point. From the DSC curve obtained in the second heating, the extrapolated glass transition onset temperature (Tig) is determined as the glass transition temperature of the resin constituting the first resin layer 11. If neither a stepwise change nor a peak due to enthalpy relaxation is observed in the DSC curve obtained in the second heating, it is determined that the resin constituting the first resin layer 11 does not have a glass transition temperature. The cold crystallization peak temperature (Tpc) is determined from the DSC curve obtained in the second heating, and is defined as the cold crystallization temperature of the resin constituting the first resin layer 11. If a cold crystallization peak cannot be confirmed in the DSC curve obtained in the second heating, it is determined that the resin constituting the first resin layer 11 does not have a cold crystallization temperature. Other conditions comply with the provisions of JIS K 7121:2012 (Method for measuring transition temperatures of plastics (JIS K 7121:1987, main body 001)).

[0071] 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 property of the polymer film 10 due to the high gas barrier property of the first resin layer 11, but also increases adhesion to the vapor-deposited film 15, thereby further improving the gas barrier property. 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.

[0072] The first resin layer 11 may contain a resin other than polyamide resin, such as polyester, acrylic resin, or ionomer resin, as long as it does not affect processability and physical properties.

[0073] The first resin layer 11 may contain one or more additives, such as a crosslinking agent, an antiblocking agent, a slip agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing agent, an antistatic agent, a pigment, a dye, and a modifying resin.

[0074] Examples of lubricants include hydrocarbon lubricants, fatty acid lubricants, fatty acid amide lubricants, ester lubricants, and metal soaps. The lubricant may be liquid or solid.

[0075] Examples of hydrocarbon-based lubricants include liquid paraffin, natural paraffin, polyethylene wax, and microcrystalline wax. Examples of fatty acid-based lubricants include stearic acid and lauric acid. Examples of fatty acid amide-based lubricants include stearic acid amide, palmitic acid amide, N-oleyl palmitic acid amide, behenic acid amide, erucic acid amide, arachidic acid amide, oleic acid amide, methylene bisstearamide, and ethylene bisstearamide. Examples of ester-based lubricants include butyl stearate, hydrogenated castor oil, ethylene glycol monostearate, and stearate monoglyceride. Examples of metal soaps include zinc stearate and calcium stearate.

[0076] 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, even more preferably 3 μm or less, even more preferably 2 μm or less, and particularly preferably 1.5 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 0.1 μm or more and 4 μm or less, even more preferably 0.2 μm or more and 3 μm or less, even more preferably 0.2 μm or more and 2 μm or less, and particularly preferably 0.3 μm or more and 1.5 μm or less.

[0077] 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.

[0078] (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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] (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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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 2.5% 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 2.5% or more and 10% or less.

[0091] 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.

[0092] (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.

[0093] 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.

[0094] 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.

[0095] 6, the polymer film 10 without the fourth resin layer 14 is laminated with a heat sealable heat sealant film 18 containing another polypropylene on the vapor-deposited 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.

[0096] 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.

[0097] 7, a laminate of three films can be prepared by laminating a polypropylene base film 19 containing polypropylene to 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 to 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.

[0098] 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.

[0099] 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.

[0100] (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, the first resin layer 11, the second resin layer 12, the third resin layer 13, and the fourth resin layer 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.

[0101] 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.

[0102] The resin layers may be formed by extruding the same or different resins using multiple extruders and then joining them together. The first resin layer 11 may be formed by extruding different polyamide resins using multiple extruders to form layers. The resin composition, obtained by mixing the resins that make up the multilayer first resin layer 11 in accordance with their respective proportions, may have no cold crystallization temperature and a glass transition temperature that is equal to or lower than a certain value.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] In this specification, the tensile strength of the polymer film 10 is measured in accordance with JIS K 7127:1999. 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%.

[0107] 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.

[0108] 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)

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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)

[0114] 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.

[0115] 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)

[0116] (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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] It is preferable to perform a plasma treatment on the surface of the vapor-deposited film 15. This can improve adhesion to a barrier coating layer 16 that will be provided on the surface of the vapor-deposited film 15, as described below.

[0129] 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.

[0130] 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 C in the above range in the carbon-containing silicon oxide vapor-deposited film, deterioration of the gas barrier property of the barrier film can be suppressed even after bending.

[0131] 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.

[0132] (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.

[0133] 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.

[0134] 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

[0135] (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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] The metal alkoxide is represented by the following general formula: １ ｎ M (OR ２ ) ｍ 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.

[0143] 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 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] The composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butanol.

[0156] 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.

[0157] The barrier coating layer 16 may have a printed layer formed on its surface.

[0158] (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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] The heat sealant film 18 is primarily composed of polypropylene having a melting point of 120°C or higher, thereby improving 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, "polyolefin having a melting point of 120°C or higher" refers to polypropylene having a melting peak temperature (Tpm) of 120°C or higher in the above-mentioned differential scanning calorimetry (DSC).

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] From the viewpoint of recyclability, the thickness of the adhesive layer 17 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. From the viewpoint of adhesiveness, the thickness of the adhesive layer 17 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1.0 μm or more. For example, the thickness of the adhesive layer 17 is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less, and even more preferably 1.0 μm or more and 3 μm or less.

[0171] (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.

[0172] 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.

[0173] 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.

[0174] The polyamide resins used in the following examples and comparative examples are as follows: Polyamide A: Amorphous aromatic polyamide, trade name: Grivory (registered trademark) G21, manufactured by M-Chemie, polyhexamethylene isophthalamide / polyhexamethylene terephthalamide copolymer (PA6I / 6T) Polyamide B: Amorphous alicyclic polyamide, trade name: Grilamid (registered trademark) TR 90, manufactured by M-Chemie, copolymer of 4,4'-methylenebis(2-methylcyclohexylamine) and dodecanedioic acid (PA MACM12) Polyamide C: A mixture of an amorphous alicyclic polyamide and a crystalline aliphatic chain polyamide, trade name: Grilamid (registered trademark) TR90LX, manufactured by M-Chemie, copolymer of 4,4'-methylenebis(2-methylcyclohexylamine) and dodecanedioic acid (PA MACM12) and polylauryllactam (PA12) Polyamide D: Amorphous aromatic polyamide, trade name: Trogamid (registered trademark) T5000, manufactured by Polypla-Evonik Co., Ltd. Copolymer of 2,2,4-trimethylhexamethylenediamine and terephthalic acid (PA NDT / INDT) Polyamide E Crystalline aromatic polyamide, trade name: S7007, manufactured by Mitsubishi Gas Chemical Company, Inc. Polymetaxylylene adipamide / polymetaxylylene isophthalamide copolymer (PAMXD6I) Polyamide F Crystalline aliphatic linear polyamide, trade name: UBE NYLON 5033B, manufactured by UBE Co., Ltd. Copolymer of 6-aminocaproic acid, hexamethylenediamine, and adipic acid (PA6 / 66) Polyamide G Amorphous aromatic polyamide, trade name: Grilamid (registered trademark) TR 30 LS, manufactured by M-Chemie Co., Ltd. Copolymer (PA6I / X) containing at least hexamethylenediamine and isophthalic acid as structural units

[0175] Example 1 Polyamide A was used as the resin constituting the first resin layer (first resin). An acid-modified polypropylene random copolymer (MFR: 5.0) was used as the resin constituting the second resin layer (second resin). Homopolypropylene (MFR: 3.0) was used as the resin constituting the third resin layer (third resin). An ethylene-1-butene-propylene random copolymer (MFR: 5.3) was used as the resin constituting the fourth resin layer (fourth resin). 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 comprising a first resin layer (0.7 μm), a second resin layer (1.3 μm), a third resin layer (17.0 μm), and a fourth resin layer (1.0 μm). The thickness of the polymer film of Example 1 was 20 μm. The polypropylene content in the entire polymer film of Example 1 was 95 mass %.

[0176] Example 2 A polymer film of Example 2 was produced in the same manner as in Example 1, except that a mixture of 30% by mass of polyamide B and 70% by mass of polyamide C was used as the first resin. １ The components of the first resin used in Example 2 were identified by H-NMR spectrum measurement, and were found to be 78.1% by mass of PA MACM12 and 21.9% by mass of PA12.

[0177] Example 3 A polymer film of Example 3 was produced in the same manner as in Example 1, except that a mixture of 50% by mass of polyamide B and 50% by mass of polyamide C was used as the first resin. １ The components of the first resin used in Example 3 were identified by H-NMR spectrum measurement, and were found to be 84.3 mass% PA MACM12 and 15.7 mass% PA12.

[0178] Example 4 A polymer film of Example 4 was produced in the same manner as in Example 1, except that a mixture of 70% by mass of polyamide B and 30% by mass of polyamide C was used as the first resin. １The constituent components of the first resin used in Example 4 were identified by H-NMR spectrum measurement, and were found to be 90.6% by mass of PA MACM12 and 9.4% by mass of PA12.

[0179] Example 5 A polymer film of Example 5 was produced in the same manner as in Example 1, except that a mixture of 80% by mass of polyamide A and 20% by mass of polyamide D was used as the first resin.

[0180] Example 6 A polymer film of Example 6 was produced in the same manner as in Example 1, except that a mixture of 60% by mass of polyamide A and 40% by mass of polyamide E was used as the first resin.

[0181] Example 7 A polymer film of Example 7 was produced in the same manner as in Example 1, except that a mixture of 60% by mass of polyamide A and 40% by mass of polyamide F was used as the first resin.

[0182] Example 8 A polymer film of Example 8 was produced in the same manner as in Example 1, except that a mixture of 50% by mass of polyamide A and 50% by mass of polyamide F was used as the first resin.

[0183] Example 9 A polymer film of Example 9 was produced in the same manner as in Example 1, except that a mixture of 70% by mass of polyamide A and 30% by mass of polyamide F was used as the first resin.

[0184] Example 10 A polymer film of Example 10 was produced in the same manner as in Example 1, except that a mixture of 50% by mass of polyamide A and 50% by mass of polyamide E was used as the first resin.

[0185] [Example 11] A polymer film of Example 11 was produced in the same manner as in Example 1, except that the thickness of the first resin layer was 0.4 μm. The thickness of the polymer film of Example 11 was 19.7 μm. The polypropylene content of the entire polymer film of Example 11 was 97 mass%.

[0186] [Example 12] A polymer film of Example 12 was produced in the same manner as in Example 1, except that the thickness of the first resin layer was 1.5 μm. The thickness of the polymer film of Example 12 was 20.8 μm. The polypropylene content of the entire polymer film of Example 12 was 91 mass%.

[0187] Comparative Example 1 A polymer film of Comparative Example 1 was produced in the same manner as in Example 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.

[0188] Comparative Example 2 A polymer film of Comparative Example 2 was produced in the same manner as in Example 1, except that polyamide E was used as the first resin.

[0189] Comparative Example 3 A polymer film of Comparative Example 3 was produced in the same manner as in Example 1, except that polyamide F was used as the first resin.

[0190] Comparative Example 4 A polymer film of Comparative Example 4 was produced in the same manner as in Example 1, except that polyamide G was used as the first resin.

[0191] [Differential Scanning Calorimetry (DSC)] The polymer films of Examples 1 to 12 and Comparative Examples 1 to 4 were cut into pieces measuring 210 mm x 297 mm, and the surface of the first resin layer was scraped off with a trimming knife (single-edged trimming razor, manufacturer's part number: 121-2) to prepare samples. A sample weighing 1.00 mg to 1.25 mg was packed into an aluminum pan, and heat flux differential scanning calorimetry (heat flux DSC), a type of differential scanning calorimetry (DSC), was performed as follows. Using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name: DSC7000X), the sample was held at 20°C for 5 minutes, then heated from 20°C to 300°C at a heating rate of 20°C / min (first heating), and held at 300°C for 5 minutes. Next, the temperature was decreased from 300°C to 20°C at a rate of 20°C / min (first temperature decrease) and held at 20°C for 5 minutes. Furthermore, the temperature was increased from 20°C to 300°C at a rate of 20°C / min (second temperature increase) and held at 300°C for 5 minutes. Indium was used for temperature calibration, and the nitrogen gas flow rate was 20 mL / min. From the DSC curve obtained in the first temperature increase, the melting peak temperature (Tpm) was determined and used as the melting point of the resin constituting the first resin layer. However, melting peak temperatures (Tpm) of 155°C or higher but less than 165°C were not considered as the melting peak temperature of the resin constituting the first resin layer. For samples in which a melting peak was not confirmed in the DSC curve obtained in the first temperature increase, it was determined that the resin constituting the first resin layer did not have a melting point. From the DSC curve obtained in the second temperature increase, the extrapolated glass transition onset temperature (Tig) was determined and used as the glass transition temperature of the resin constituting the first resin layer. For samples in which neither a stepwise change nor a peak due to enthalpy relaxation was observed in the DSC curve obtained in the second heating, it was determined that the resin constituting the first resin layer did not have a glass transition temperature. The cold crystallization peak temperature (Tpc) was calculated from the DSC curve obtained in the second heating, and was defined as the cold crystallization temperature of the resin constituting the first resin layer. For samples in which neither a cold crystallization peak was observed in the DSC curve obtained in the second heating, it was determined that the resin constituting the first resin layer did not have a cold crystallization temperature. Other conditions were in accordance with the provisions of JIS K 7121:2012 (Method for measuring transition temperatures of plastics (JIS K 7121:1987, main body 001)). The results are shown in Table 1.In Table 1, "-" means that the melting peak temperature, cold crystallization peak temperature, or extrapolated glass transition onset temperature could not be confirmed from the DSC curve.

[0192] [Evaluation of film-forming properties] The state of each of the polymer films of Examples 1 to 12 and Comparative Examples 1 to 4 immediately after production was evaluated based on the following evaluation criteria. The results are shown in Table 1. A: The polymer film was not curled, and film-forming properties were excellent. B: The polymer film curled toward the first resin layer side, but not significantly, and film-forming properties were acceptable for practical use. C: The polymer film curled significantly toward the first resin layer side, and film-forming properties were not acceptable for practical use. D: The first resin layer was broken, and film-forming properties were poor.

[0193] [Heat Resistance Evaluation] The polymer films of Examples 1 to 12 and Comparative Examples 1 to 3, in which the first resin layer did not break, were each cut into a 100 mm x 100 mm piece. Next, the polymer films were placed on a flat metal plate with the fourth resin layer facing downward. Photographs of the polymer films were taken at a point 50 cm vertically above the center of the polymer film. The photographs were used to measure the contact area between the polymer film and the flat metal plate. The polymer films were subjected to a heat treatment at 120°C for 20 minutes. The contact area between the polymer film and the flat metal plate after the heat treatment was also measured using the same procedure as before the heat treatment. The contact area after the heat treatment was divided by the contact area before the heat treatment to calculate the contact area ratio of the polymer film after the heat treatment. A larger contact area ratio after the heat treatment indicated less curling due to the heat treatment and better heat resistance of the polymer film. The results are shown in Table 1.

[0194] Examples 1A to 12A and Comparative Example 1A: An aluminum oxide (alumina) vapor-deposited film was formed on the surface of the first resin layer of the polymer film of Examples 1 to 12 and Comparative Example 1, which had relatively good film-forming properties, by the following procedure. The polymer film 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 1:1 volumetric argon / oxygen mixed gas 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 resistance heating as an aluminum heating means while introducing oxygen, forming a 10 nm-thick aluminum oxide vapor-deposited film (PVD method). Next, a barrier coating agent was prepared on the surface of the aluminum oxide 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, yielding 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 yield solution B. Solutions A and 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 at 100°C for 10 seconds. The thickness of the barrier coating layer formed by drying the barrier coating agent was 300 nm. In this manner, the barrier films of Examples 1A to 12A and Comparative Example 1A were produced from the polymer films of Examples 1 to 10 and Comparative Example 1, respectively.

[0195] [Preparation of Laminates] Laminates were prepared using the barrier films of Examples 1A to 12A and Comparative Example 1A by the following procedure. 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. This printed layer was bonded to the barrier coat layer surface of the barrier film using a two-component curing polyurethane adhesive. The adhesive layer formed by the two-component curing polyurethane adhesive had a thickness of 2 μm. Next, an unstretched polypropylene film with a thickness of 50 μm was prepared as the heat sealant film. The surface of the fourth resin layer of the barrier film and the heat sealant film were bonded to each other using a two-component curing polyurethane adhesive. The adhesive layer formed by the two-component curing polyurethane adhesive had a thickness of 2 μm. In this manner, laminates including the barrier films of Examples 1A to 12A and Comparative Example 1A were each prepared.

[0196] Examples 1B to 6B, 8B, and 10B, and Comparative Example 1B: Silicon oxide vapor-deposited films were formed on the surface of the first resin layer of the polymer films of Examples 1 to 6, 8, and 10, and Comparative Example 1, by the following procedure. A polymer film was introduced into an unwinding compartment of a decompressible chamber having an unwinding compartment, a plasma treatment compartment, a film-forming compartment, a winding compartment, and other compartments, and the chamber was depressurized. Using a plasma treatment device, the surface of the first resin layer of the polymer film was subjected to plasma pretreatment using argon gas in a roll-to-roll manner while applying tension to the polymer film. In the continuously transported film-forming compartment, silicon oxide was vapor-deposited on the plasma-treated surface using electron beam heating as a heating means, using silicon monoxide as a vapor deposition source, to form a 30 nm-thick silicon oxide vapor-deposited film (PVD method). In this manner, barrier films of Examples 1B to 6B, 8B, and 10B, and Comparative Example 1B were produced from the polymer films of Examples 1 to 6, 8, and 10, and Comparative Example 1, respectively.

[0197] [Preparation of Laminates] Laminates were prepared using the barrier films of Examples 1B to 6B, 8B, and 10B and Comparative Example 1B by the following procedure. 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. This printed layer was bonded to the silicon oxide vapor-deposited film side of the barrier film using a two-component curing polyurethane adhesive. The adhesive layer formed with the two-component curing polyurethane adhesive had a thickness of 2 μm. Next, an unstretched polypropylene film with a thickness of 50 μm was prepared as the heat sealant film. The surface of the fourth resin layer of the barrier film and the heat sealant film were bonded to each other using a two-component curing polyurethane adhesive. The adhesive layer formed with the two-component curing polyurethane adhesive had a thickness of 2 μm. In this manner, laminates including the barrier films of Examples 1B to 6B, 8B, and 10B and Comparative Example 1B were each prepared.

[0198] Example 10C A carbon-containing silicon oxide vapor-deposited film was formed on the surface of the first resin layer of the polymer film of Example 10 by the following procedure. The polymer film 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-enhanced chemical vapor deposition apparatus (plasma CVD apparatus), the surface of the first resin layer of the polymer film was subjected to plasma pretreatment using a 1:1 volumetric ratio argon and oxygen mixed gas in a roll-to-roll manner while applying tension to the polymer film. A carbon-containing silicon oxide vapor-deposited film having a thickness of 30 nm was formed on the plasma-treated surface in the continuously transported film-forming compartment (CVD method). The vapor-deposited film formation conditions were as follows: (Forming conditions) Hexamethyldisiloxane:oxygen gas:helium=1:10:10 (unit: slm) Power supplied to electrode drum: 22 kW Line speed: 40 m / min In this manner, a barrier film of Example 10C was produced from the polymer film of Example 10.

[0199] [Preparation of Laminate] A laminate was prepared using the barrier film of Example 10C by the following procedure. 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. This printed layer was bonded to the carbon-containing silicon oxide vapor-deposited film side of the barrier film using a two-component curing polyurethane adhesive. The adhesive layer formed with the two-component curing polyurethane adhesive had a thickness of 2 μm. Next, an unstretched polypropylene film with a thickness of 50 μm was prepared as the heat sealant film. The surface of the fourth resin layer of the barrier film and the heat sealant film were bonded to each other using a two-component curing polyurethane adhesive. The adhesive layer formed with the two-component curing polyurethane adhesive had a thickness of 2 μm. In this manner, a laminate including the barrier film of Example 10C was prepared.

[0200] [Evaluation of gas barrier properties before retort treatment] Test pieces were obtained by cutting out the laminates including the barrier films of Examples 1A to 12A and Comparative Example 1A, the laminates including the barrier films of Examples 1B to 6B, 8B, and 10B and Comparative Example 1B, and the laminate including the barrier film of Example 10C. The test pieces were used to measure the oxygen permeability (unit: cc / (m ２ ·day·atm) and water vapor permeability (unit: g / (m ２ The oxygen permeability was measured by the following method. The results are shown in Tables 2 to 4. (Oxygen Permeability) Using an oxygen permeability measuring device (OX-TRAN2 / 20, manufactured by MOCON Corporation), the test piece was set so that the heat sealant film side was 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 test piece was set so that the heat sealant film side was 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.

[0201] [Evaluation of Gas Barrier Properties After Retort Treatment at 121°C and 0.2 MPa for 30 Minutes] Laminates equipped with the barrier films of Examples 1A to 12A and Comparative Example 1A were cut into A4 size, folded in half at the long edge to face the heat sealant film, and heat-sealed along three edges, including the fold, to a width of 7 mm to produce three-sided sealed packaging bags. This three-sided sealed packaging bag was filled with 200 mL of tap water, and the remaining edge was heat-sealed to form a retort packaging bag filled with the contents. The retort packaging bag was subjected to a retort treatment at 121°C and 0.20 MPa for 30 minutes using steam. Laminates were cut out from the retort packaging bag after retort treatment, and the oxygen permeability and water vapor permeability were measured in the same manner. The results are shown in Table 2.

[0202] [Evaluation of Gas Barrier Properties After Retort Treatment at 125°C and 0.25 MPa for 30 Minutes] Laminates equipped with the barrier films of Examples 1A to 10A and Comparative Example 1A were cut into A4 size, folded in half at the long edge to face the heat sealant film, and heat-sealed along three sides, including the fold, to a width of 7 mm to produce three-sided sealed packaging bags. This three-sided sealed packaging bag was filled with 200 mL of tap water, and the remaining side was heat-sealed to seal the contents, forming a retort packaging bag. The retort packaging bag was subjected to a retort treatment at 125°C and 0.25 MPa for 30 minutes using steam. Laminates were cut out from the retort packaging bag after retort treatment, and the oxygen permeability and water vapor permeability were measured in the same manner. The results are shown in Table 2.

[0203] [Evaluation of Gas Barrier Properties After Retort Treatment at 130°C and 0.30 MPa for 60 Minutes] Laminates equipped with the barrier films of Examples 1A and 5A, laminates equipped with the barrier films of Examples 1B to 6B, 8B, and 10B and Comparative Example 1B, and laminates equipped with the barrier film of Example 10C were cut into A4 size, folded in half along the long side to face the heat sealant film, and heat-sealed along three sides, including the fold, to a width of 7 mm to produce three-sided sealed packaging bags. This three-sided sealed packaging bag was filled with 200 mL of tap water, and the remaining side was heat-sealed to seal the contents, forming a retort pouch. The retort pouch was subjected to a retort treatment at 130°C and 0.30 MPa for 60 minutes using steam. Laminates were cut out of the retort pouch after retort treatment, and the oxygen permeability and water vapor permeability were similarly measured. The results are shown in Tables 2 to 4.

[0204]

[0205]

[0206]

[0207]

[0208] As is clear from Table 1 above, the polymer films of Examples 1 to 12, in which the resin constituting the first resin layer did not exhibit a cold crystallization temperature and the resin constituting the first resin layer had a glass transition temperature of 155°C or lower, were excellent in film formability, had a large contact area ratio after heat treatment, and were excellent in heat resistance. As is clear from Table 2 above, the laminates including the barrier films of Examples 1A to 12A had smaller oxygen permeability and water vapor permeability than the barrier film of Comparative Example 1A, both before retort treatment and after retort treatment at 121°C, 0.20 MPa, for 30 minutes, and were therefore excellent in gas barrier properties. As is clear from Table 2 above, the laminates comprising the barrier films of Examples 1A to 6A and 10A, which did not contain a linear aliphatic polyamide in the first resin layer, had lower oxygen permeabilities and water vapor permeabilities after retort treatment at 125°C, 0.25 MPa, for 30 minutes, and thus exhibited superior gas barrier properties after retort treatment under more severe conditions, compared with the laminates comprising the barrier films of Examples 7A to 9A, which contained a linear aliphatic polyamide in the first resin layer. As is clear from Tables 2 to 4 above, the laminates comprising the barrier films of Examples 1B to 6B, 8B, and 10B, which had a silicon oxide vapor-deposited film, and the laminate comprising the barrier film of Example 10C, which had a carbon-containing silicon oxide vapor-deposited film, had lower oxygen permeabilities after retort treatment at 130°C, 0.30 MPa, for 60 minutes, and thus exhibited superior oxygen barrier properties after retort treatment under even more severe conditions, compared with the barrier films of Examples 1A and 5A, which had an aluminum oxide vapor-deposited film. As is clear from Tables 2 to 4 above, the laminates comprising the barrier films of Examples 1B to 6B, 8B and 10B having a silicon oxide vapor-deposited film had lower water vapor permeabilities after retort treatment at 130°C, 0.30 MPa for 60 minutes, and were also excellent in water vapor barrier properties after retort treatment under even harsher conditions, compared to the barrier films of Examples 1A and 5A having an aluminum oxide vapor-deposited film.

[0209] 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, the resin constituting the first resin layer does not have a cold crystallization temperature, and the resin constituting the first resin layer has a glass transition temperature of 155°C or lower, the second resin layer comprises an acid-modified product of polypropylene, and the third resin layer comprises homopolypropylene.

2. The polymer film according to claim 1, wherein the first resin layer contains one type of polyamide resin.

3. The polymer film according to claim 2, wherein the content of the polyamide resin in the first resin layer is 70% by mass or more.

4. The polymer film according to claim 1, wherein the polyamide resin contained in the first resin layer is a first polyamide and a second polyamide, the first polyamide being an aromatic polyamide or an alicyclic polyamide, and the second polyamide being an aromatic polyamide, an alicyclic polyamide, or an aliphatic chain polyamide.

5. The polymer film according to claim 4, wherein the content of the first polyamide in the first resin layer is 50% by mass or more and 95% by mass or less.

6. The polymer film according to claim 4 or 5, wherein the content of the second polyamide in the first resin layer is 5% by mass or more and 50% by mass or less.

7. The polymer film according to any one of claims 1 to 5, wherein the resin constituting the first resin layer does not have a melting point.

8. The polymer film according to any one of claims 1 to 5, wherein the polypropylene content in the polymer film is 70% by mass or more.

9. The polymer film according to any one of claims 1 to 5, 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) 10. The polymer film according to any one of claims 1 to 5, 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.

11. A barrier film comprising the polymer film according to any one of claims 1 to 5 and a vapor-deposited film containing an inorganic oxide, the vapor-deposited film being provided on the first resin layer side.

12. The barrier film according to claim 11, which comprises a barrier coating layer on the vapor-deposited film side.

13. A laminate comprising the barrier film of claim 11 and a heat sealant film.

14. The laminate of claim 13, further comprising a polypropylene substrate film.

15. A packaging bag comprising the laminate according to claim 13.

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