Laminate, packaging material, packaging bag, and package

Abstract

The present invention addresses the problem of providing a laminate, a packaging material, a packaging bag, and a package with which it is possible to manufacture a packaging bag that has gas barrier properties and is exceptional in terms of the appearance and the heat seal strength of a heat seal part. The laminate includes: a biaxially oriented polypropylene film including a base material layer A composed of a polypropylene-based resin composition, a surface layer B composed of a polypropylene-based resin composition, and a surface layer C composed of a polypropylene-based resin composition; and a gas barrier layer. The laminate satisfies (1) to (4). (1) The thermal shrinkage at 150°C in the longitudinal direction of the biaxially oriented polypropylene film is 0.0-10.0%. (2) The thermal shrinkage at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0-15.0%. (3) The anti-blocking agent falling rate of both the surface layer B and the surface layer C is 10% or less. (4) The laminate strength of the laminate is 1.5 N / 15 mm or greater.

Description

Laminate, packaging material, packaging bag, and packaging body

[0001] The present invention relates to a laminate, a packaging material, a packaging bag, and a packaging body using a biaxially oriented polypropylene film.

[0002] Biaxially oriented polypropylene films have been widely used as packaging materials for foods, textile products, and other articles because of their excellent transparency and mechanical properties.

[0003] Food packaging requires films to have gas barrier properties. Because biaxially oriented polypropylene films have inferior oxygen barrier properties compared to nylon and polyester films, they are sometimes laminated with a gas barrier layer. Furthermore, food packaging bags are often laminated with a printed layer to enhance content display and design. That is, laminate films used for food packaging include a printed film, a film laminated with a gas barrier layer, and a heat-sealable film (also called a sealant film) for heat sealing. For example, a laminate having a structure of a printing substrate layer / printing layer / adhesive layer / inorganic thin film layer / deposition substrate layer / adhesive layer / sealant film is used, in which the substrate layers and the sealant film are made of the same polypropylene material from the viewpoint of recycling (Patent Document 1).

[0004] When printing or vapor deposition is performed on biaxially oriented polypropylene film, the non-polar nature of polypropylene resin results in low surface energy, which can result in insufficient adhesion to printing inks, coating layers, vapor deposition layers, etc.

[0005] As a biaxially oriented polypropylene film with improved adhesion to printing ink, for example, Patent Document 2 discloses a film having a surface layer with a predetermined surface roughness and wetting tension. In addition, in the case of providing an aluminum vapor-deposited film on biaxially oriented polypropylene, for example, Patent Document 3 discloses a film with a surface layer having a relatively small surface roughness and a predetermined wetting tension as a film with excellent adhesion to the aluminum vapor-deposited film.

[0006] International Publication No. WO2021 / 020400 International Publication No. WO2018 / 142983 International Publication No. WO2022 / 004340

[0007] However, the film described in Patent Document 2 had poor adhesion to an aluminum vapor-deposited film when a printed layer or an aluminum vapor-deposited film was provided on the surface layer. Therefore, the laminate strength of a laminate further laminated with a heat-sealable film was also poor. Furthermore, the film described in Patent Document 3 was unstable in longitudinal stretching, resulting in poor film formability, and the resulting film had poor appearance and unstable physical properties.

[0008] An object of the present invention is to provide a laminate and a packaging material that can be used to produce a packaging bag that has gas barrier properties and is excellent in appearance and heat seal strength at the heat seal portion.An object of the present invention is also to provide a packaging bag or a package.

[0009] The present invention has the following configuration 1. 1. A laminate comprising a biaxially oriented polypropylene film including a base layer A made of a polypropylene-based resin composition, a surface layer B made of a polypropylene-based resin composition, and a surface layer C made of a polypropylene-based resin composition, and a gas barrier layer provided on surface layer B or surface layer C, wherein the laminate satisfies the following (1) to (4): (1) The heat shrinkage rate at 150°C in the longitudinal direction of the biaxially oriented polypropylene film is 0.0% or more and 10.0% or less. (2) The heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 15.0% or less. (3) Both surface layer B and surface layer C contain an antiblocking agent, and the dropout rate of the antiblocking agent in both surface layer B and surface layer C is 10% or less. (4) The laminate strength of the laminate is 1.5 N / 15 mm or more.

[0010] The present invention preferably further comprises the following configuration 2. and subsequent configurations. 2. The laminate according to 1., wherein the surface of the surface layer B and / or the surface layer C has a surface wet tension of 36 mN / m or more. 3. The laminate according to 1. or 2., wherein the surface layer B and the surface layer C contain 25% by mass or more and 85% by mass or less of a polypropylene-based resin having a melting point of 130°C or more and 158°C or less. 4. The laminate according to any of 1. to 3., wherein the polypropylene-based resin composition of the base layer A has a mesopentad fraction ([mmmm]%) of 95.0% or more and 99.9% or less and contains 70% by mass or more of a polypropylene-based resin having a melting point of 160°C or more and 175°C or less. 5. The laminate according to any of 1. to 4., wherein the surface resistivity of the surface layer B and / or the surface layer C is 14.0 Log Ω or more. 6. The laminate according to any one of 1. to 5., wherein the gas barrier layer is an inorganic thin film layer containing aluminum, aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide. 7. The laminate according to any one of 1. to 5., wherein the gas barrier layer is a coating layer containing one or more of a polyvinyl alcohol resin, a polyester resin, a polyurethane resin, and an inorganic layered compound. 8. The laminate according to any one of 1. to 7., further comprising an anchor coat layer between the biaxially oriented polypropylene film and the gas barrier layer. 9. The laminate according to any one of 1. to 6. and 8., further comprising a protective layer laminated on the gas barrier layer. 10. The laminate according to any one of 1. to 9., which is used for microwave heating. 11. The laminate according to any one of 1. to 10., wherein the polypropylene-based resin composition of the base layer A contains a polypropylene homopolymer. 12. The laminate according to 11., wherein the content of the polypropylene homopolymer in the polypropylene-based resin composition of the base layer A is 60% by mass or more, or 70% by mass or more. 13. 11. The laminate according to 11., wherein the content of the polypropylene homopolymer in the polypropylene-based resin composition of the base layer A is 80% by mass or more, or 90% by mass or more. 14. The laminate according to 11., wherein the content of the polypropylene homopolymer in the polypropylene-based resin composition of the base layer A is 95% by mass or more, or 98% by mass or more.15. The laminate according to any one of 1. to 14., wherein the polypropylene resin composition of the surface layer B contains a polypropylene resin having a melting point of 130°C or higher and 158°C or lower. 16. The laminate according to 15., wherein the polypropylene resin of the surface layer B has a melting point of 150°C or lower, or 143°C or lower. 17. The laminate according to 15. or 16., wherein the polypropylene resin of the surface layer B has a melting point of 134°C or higher, or 138°C or higher. 18. The laminate according to any one of 15. to 17., wherein the polypropylene resin of the surface layer B is a polypropylene resin copolymerized with at least ethylene and / or an α-olefin having 4 or more carbon atoms. 19. The laminate according to any one of 15. to 18., wherein the polypropylene resin (specifically, the polypropylene resin having a melting point of 130°C or higher and 158°C or lower) in the polypropylene resin composition of the surface layer B is 25% by mass or higher, or 30% by mass or higher. 20. The laminate according to any one of 15. to 19., wherein the polypropylene-based resin composition of the surface layer B contains 35% by mass or more of the polypropylene-based resin (specifically, the polypropylene-based resin having a melting point of 130°C or more and 158°C or less). 21. The laminate according to any one of 15. to 20., wherein the polypropylene-based resin composition of the surface layer B contains 85% by mass or less, or 80% by mass or less of the polypropylene-based resin (specifically, the polypropylene-based resin having a melting point of 130°C or more and 158°C or less). 22. The laminate according to any one of 15. to 21., wherein the polypropylene-based resin composition of the surface layer B contains 75% by mass or less of the polypropylene-based resin (specifically, the polypropylene-based resin having a melting point of 130°C or more and 158°C or less). 23. The polypropylene-based resin composition of the surface layer C contains a polypropylene-based resin having a melting point of 130°C or more and 158°C or less. 24. The laminate according to any one of 23., 24. The laminate according to 23., 25. The laminate according to 23. or 24 ...26. The laminate according to any one of 23. to 25., wherein the polypropylene resin of the surface layer C is a polypropylene resin copolymerized with at least ethylene and / or an α-olefin having 4 or more carbon atoms. 27. The laminate according to any one of 23. to 26., wherein the polypropylene resin composition of the surface layer C contains 25% by mass or more of the polypropylene resin (specifically, the polypropylene resin having a melting point of 130°C or more and 158°C or less) in an amount of 25% by mass or more, or 30% by mass or more. 28. The laminate according to any one of 23. to 27., wherein the polypropylene resin composition of the surface layer C contains 35% by mass or more of the polypropylene resin (specifically, the polypropylene resin having a melting point of 130°C or more and 158°C or less). 29. The laminate according to any one of 23. to 28., wherein the polypropylene-based resin composition of the surface layer C contains 85% by mass or less, or 80% by mass or less of the polypropylene-based resin (specifically, the polypropylene-based resin having a melting point of 130°C or more and 158°C or less). 30. The laminate according to any one of 23. to 29., wherein the polypropylene-based resin composition of the surface layer C contains 75% by mass or less of the polypropylene-based resin (specifically, the polypropylene-based resin having a melting point of 130°C or more and 158°C or less). 31. A packaging material comprising the laminate according to any one of 1. to 30., and a film laminated on the laminate. 32. The packaging material according to 31., wherein the film laminated on the laminate is a heat-sealable polyolefin film. 33. The laminate has a first surface on which the heat-sealable polyolefin film is laminated, and a second surface opposite to the first surface, and further contains a stretched polyolefin film or a stretched polyester film laminated on the second surface of the laminate. 34. The packaging material according to any one of 31. to 33., further comprising an adhesive layer laminated on the gas barrier layer. 35. A packaging bag constructed using the packaging material according to any one of 31. to 34. 36. A package comprising the packaging bag according to 35. and an item to be packaged in the packaging bag.

[0011] According to the present invention, it is possible to provide a laminate and a packaging material from which a packaging bag having gas barrier properties and excellent heat-sealed portion appearance and heat-sealing strength can be produced. According to the present invention, it is also possible to provide a packaging bag or a package.

[0012] [Introduction] A laminate according to an embodiment of the present invention comprises a biaxially oriented polypropylene film including a base layer A made of a polypropylene-based resin composition, a surface layer B made of a polypropylene-based resin composition, and a surface layer C made of a polypropylene-based resin composition, and a gas barrier layer provided on surface layer B or surface layer C. The laminate according to an embodiment of the present invention satisfies the following (1) to (4): (1) The heat shrinkage rate at 150°C in the longitudinal direction of the biaxially oriented polypropylene film is 0.0% or more and 10.0% or less. (2) The heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 15.0% or less. (3) Both surface layer B and surface layer C contain an antiblocking agent, and the dropout rate of the antiblocking agent in both surface layer B and surface layer C is 10% or less. (4) The laminate strength of the laminate is 1.5 N / 15 mm or more. Here, the "lamination strength of the laminate" is measured by the method described in the Examples below (specifically, see the method for measuring the laminate strength using the second evaluation film). When producing the second evaluation film, the unstretched polypropylene film P1153-50 μm (CPP1) is laminated to the gas barrier layer or protective layer (when the laminate according to the embodiment of the present invention includes a protective layer) of the laminate according to the embodiment of the present invention.

[0013] Because the laminate according to the embodiment of the present invention includes a gas barrier layer, it has superior oxygen barrier properties or water vapor barrier properties compared to laminates that do not include a gas barrier layer. Furthermore, because the laminate according to the embodiment of the present invention satisfies the above-mentioned (1) and (2), when a packaging bag having a heat-sealed portion is produced using the laminate according to the embodiment of the present invention, excessive wrinkling of the heat-sealed portion due to the heat applied to the laminate by heat sealing can be prevented or reduced. Therefore, a packaging bag with excellent appearance of the heat-sealed portion can be produced. Moreover, because the laminate according to the embodiment of the present invention satisfies the above-mentioned (3), it can prevent or reduce excessive contamination of the guide roll with the antiblocking agent when slitting a biaxially oriented polypropylene film. Furthermore, because the laminate according to the embodiment of the present invention satisfies the above-mentioned (4), it can produce a packaging bag with excellent heat-sealing strength.

[0014] The gas barrier layer may be an inorganic thin film layer. The inorganic thin film layer may contain aluminum, aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide. When the gas barrier layer is an inorganic thin film layer, one of both surfaces of the laminate, i.e., a pair of outer surfaces, may be formed of an inorganic thin film layer, and the other surface may be formed of a biaxially oriented polypropylene film. The laminate according to the embodiment of the present invention may further include a protective layer. Here, the term "protective layer" refers to a layer provided on the inorganic thin film layer to protect the surface of the inorganic thin film layer. When the laminate according to the embodiment of the present invention includes a protective layer, at least a biaxially oriented polypropylene film, an inorganic thin film layer, and a protective layer may be stacked in this order. That is, at least a biaxially oriented polypropylene film, an inorganic thin film layer, and a protective layer may be arranged in this order in the thickness direction of the laminate. When the laminate according to the embodiment of the present invention includes a protective layer, one of both surfaces of the laminate may be formed of a protective layer, and the other surface may be formed of a biaxially oriented polypropylene film. The laminate according to the embodiment of the present invention may further include an anchor coat layer between the biaxially oriented polypropylene film and the inorganic thin film layer. Therefore, when the laminate according to an embodiment of the present invention includes an anchor coat layer, at least a biaxially oriented polypropylene film, an anchor coat layer, an inorganic thin film layer, and a protective layer can be arranged in this order in the thickness direction of the laminate.

[0015] On the other hand, the gas barrier layer may be a layer containing one or more of a polyvinyl alcohol resin, a polyester resin, a polyurethane resin, and an inorganic layered compound (hereinafter, sometimes referred to as a "coating layer"). When the gas barrier layer is a coating layer, one of the two surfaces of the laminate may be formed of a coating layer, and the other surface may be formed of a biaxially oriented polypropylene film. The laminate according to an embodiment of the present invention may further include an anchor coat layer between the biaxially oriented polypropylene film and the coating layer.

[0016] Hereinafter, embodiments of the present invention will be described in detail. Hereinafter, a laminate according to an embodiment of the present invention may be simply referred to as the "laminate of the present invention." A packaging material according to an embodiment of the present invention may be simply referred to as the "packaging material of the present invention." Hereinafter, the coating layer may be referred to as the "coating layer D." The inorganic thin film layer may be referred to as the "inorganic thin film layer E." The anchor coat layer may be referred to as the "anchor coat layer F." The protective layer may be referred to as the "protective layer G."

[0017] [Biaxially oriented polypropylene film] The biaxially oriented polypropylene film used in the laminate of the present invention, i.e., the biaxially stretched polypropylene film, has a base layer A made of a polypropylene-based resin composition, a surface layer B made of a polypropylene-based resin composition, and a surface layer C made of a polypropylene-based resin composition.

[0018] [Substrate Layer A] The substrate layer A preferably enhances the thermal dimensional stability, mechanical strength, and transparency of the biaxially oriented polypropylene film. The polypropylene resin composition of the substrate layer A preferably contains a polypropylene resin as a main component. In this specification, "main component" refers to a component that accounts for 70% by mass or more of the entire substrate layer A. Therefore, "the polypropylene resin composition of the substrate layer A contains a polypropylene resin as a main component" means that the polypropylene resin accounts for 70% by mass or more of the polypropylene resin composition of the substrate layer A (100% by mass). The polypropylene resin composition of the substrate layer A more preferably contains 80% by mass or more of the polypropylene resin of the entire substrate layer A, even more preferably 90% by mass or more of the entire substrate layer A, and particularly preferably 95% by mass or more of the entire substrate layer A.

[0019] Various suitable physical properties of polypropylene-based resins are described below, but when two or more different polypropylene-based resins are used, it is preferable that the mass average values ​​of the physical properties of each polypropylene-based resin fall within the numerical ranges described below.

[0020] The polypropylene resin used in the base layer A preferably has a melting point of 160°C or higher and 175°C or lower, more preferably 164°C or higher and 173°C or lower, and even more preferably 166°C or higher and 171°C or lower. A melting point of 160°C or higher can improve thermal dimensional stability and mechanical strength. A melting point of 175°C or lower can easily suppress cost increases in polypropylene production and make the film less likely to break during film formation. The melting point can also be further increased by blending a crystal nucleating agent with the polypropylene resin. The melting point was measured using a differential scanning calorimeter (DSC). A 5 mg sample was placed in an aluminum pan, melted at 230°C for 5 minutes under a nitrogen atmosphere, cooled to 30°C at a scanning rate of -10°C / min, held for 5 minutes, and then heated at a scanning rate of 10°C / min. This is the main peak temperature of the endothermic peak associated with melting observed when the sample was placed in an aluminum pan, melted at 230°C for 5 minutes under a nitrogen atmosphere, cooled to 30°C at a scanning rate of -10°C / min, held for 5 minutes, and then heated again at a scanning rate of 10°C / min.

[0021] The polypropylene resin used in the base layer A preferably has a mesopentad fraction ([mmmm]%), an index of stereoregularity, of 95.0 to 99.9%, more preferably 97.0 to 99.7%, even more preferably 97.5 to 99.5%, and particularly preferably 98.0 to 99.3%. When the mesopentad fraction is 95.0% or higher, the crystallinity of the polypropylene resin is enhanced, improving the melting point, crystallinity, and crystalline orientation of the crystals in the base layer A, thereby increasing thermal dimensional stability and mechanical strength. When the mesopentad fraction is 99.9% or lower, the cost of polypropylene production is easily reduced and the film is less likely to break during film formation. The mesopentad fraction is measured by nuclear magnetic resonance (NMR).

[0022] The melt flow rate (MFR) of the polypropylene resin used in the base layer A, when measured in accordance with JIS K 7210 (1995) condition M (230°C, 2.16 kgf), is preferably 4.0 to 30 g / 10 min, more preferably 4.5 to 25 g / 10 min, even more preferably 4.8 to 22 g / 10 min, particularly preferably 5.0 to 20 g / 10 min, and most preferably 5.5 to 10 g / 10 min. When the MFR of the polypropylene resin is 4.0 g / 10 min or more, the amount of low molecular weight components in the polypropylene resin constituting the base layer A increases, which further promotes oriented crystallization of the polypropylene resin, makes it easier to increase the crystallinity in the base layer A, and reduces entanglement of polypropylene molecular chains in the amorphous portion, thereby improving thermal dimensional stability and mechanical strength. Furthermore, when the MFR of the polypropylene resin is 30 g / 10 min or less, the film formability is easily maintained.

[0023] The polypropylene resin used in the base layer A preferably has a weight average molecular weight (Mw) of 180,000 to 500,000. If the Mw is less than 180,000, the melt viscosity is low, which may result in instability during casting and poor film formability. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less decreases, which may result in a reduced heat shrinkage rate at high temperatures. The Mw is more preferably 190,000 to 400,000, even more preferably 200,000 to 380,000, and particularly preferably 210,000 to 350,000.

[0024] The number average molecular weight (Mn) of the polypropylene resin used in the base layer A is preferably 20,000 to 200,000. If it is less than 20,000, the melt viscosity will be low, which may result in instability during casting and poor film formability. If it exceeds 200,000, the heat shrinkage rate at high temperatures may decrease. Mn is more preferably 30,000 to 120,000, even more preferably 40,000 to 110,000, particularly preferably 50,000 to 100,000, and most preferably 60,000 to 90,000.

[0025] The polypropylene resin used in the base layer A preferably has an Mw / Mn ratio, an index of molecular weight distribution, of 2.8 to 10. It is more preferably 3.0 to 8.0, even more preferably 3.2 to 6.0, and particularly preferably 3.5 to 5.0. When the Mw / Mn of the polypropylene resin is 2.8 or higher, the proportion of low-molecular-weight components in the polypropylene resin constituting the base layer A increases, which further promotes oriented crystallization of the polypropylene resin, makes it easier to increase the crystallinity in the base layer A, and reduces entanglement of polypropylene molecular chains in the amorphous portion, thereby improving thermal dimensional stability and mechanical strength. The molecular weight distribution of the polypropylene resin can be adjusted by polymerizing components of different molecular weights in a series of plants in multiple stages, blending components of different molecular weights offline in a kneader, blending and polymerizing catalysts with different performances, or using a catalyst that can achieve the desired molecular weight distribution.

[0026] (Polypropylene Homopolymer) The polypropylene-based resin used in the base layer A is preferably a polypropylene homopolymer. The polypropylene homopolymer is a polypropylene polymer that is substantially free of α-olefin components other than propylene, specifically a polypropylene (co)polymer having 1 mol% or less of α-olefin components other than propylene and 99 mol% or more of propylene as structural units. In this specification, the term "polypropylene homopolymer" includes not only polypropylene homopolymers that contain no α-olefin components other than propylene, but also polypropylene copolymers having 1 mol% or less of α-olefin components other than propylene and 99 mol% or more of propylene as structural units. Even when α-olefin components other than propylene are contained, the content of α-olefin components other than propylene (the total amount of ethylene and α-olefins having 4 or more carbon atoms) is 1 mol% or less, as described above, preferably 0.3 mol% or less, more preferably 0.2 mol% or less, and even more preferably 0.1 mol% or less. Within the above range, crystallinity is likely to be improved. Examples of the α-olefin component having 4 or more carbon atoms include 1-butene, 1-pentene, 3-methyl-1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 5-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, etc. As the polypropylene homopolymer, two or more different polypropylene homopolymers can also be used.

[0027] The content of the polypropylene homopolymer in the base layer A is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, even more preferably 80 to 100 mass%, still more preferably 90 to 100 mass%, particularly preferably 95 to 100 mass%, and most preferably 98 to 100 mass%.

[0028] (Other than polypropylene homopolymer) The propylene-based resin composition constituting the base layer A may contain additives or other resins other than polypropylene homopolymer. Examples of additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, inorganic or organic fillers, etc. Examples of other resins include polyolefin resins other than the polypropylene homopolymer used in the base layer A, and various elastomers. These may be sequentially polymerized using a multi-stage reactor, blended with a polypropylene-based resin using a Henschel mixer, master pellets prepared in advance using a melt kneader may be diluted with a polypropylene-based resin to a predetermined concentration, or the entire amount may be melt-kneaded and used in advance. If the surface resistance of the polypropylene-based resin used in the base layer A alone is too high, a surfactant may be added to reduce the surface resistance.

[0029] [Surface Layer B and Surface Layer C] When various functional layers such as a printed layer, a vapor-deposited layer, or a coating layer are provided on the surface, the surface layer B and the surface layer C preferably have high adhesion to the functional layer, and are also preferably provided with slip properties and anti-blocking properties. The functional layer is a layer having at least one function such as adhesion, coating properties, design properties, water vapor barrier properties, oxygen barrier properties, thermal conductivity, low dielectric properties, high dielectric properties, and heat resistance, and examples thereof include a printed layer, a vapor-deposited layer, and a coating layer.

[0030] The raw material composition and properties of surface layer B and surface layer C may be the same or different. The raw material composition and properties can also be changed depending on the purpose of each of surface layer B and surface layer C. For example, if it is desired to make the surface adhesion of surface layer B higher than that of surface layer C, it is preferable to blend more polypropylene-based resin with a melting point of 130°C or higher and 158°C or lower in surface layer B than in surface layer C. The reverse is also possible. Furthermore, by adjusting the type, particle size, and blending amount of the antiblocking agent described below, it is possible to improve the gas barrier properties of the vapor deposition layer by making the surface protrusions on one surface small and smooth, and to impart slip properties and antiblocking properties by making the surface protrusions on the other surface large.

[0031] Surface layer B and / or surface layer C preferably contain a polypropylene-based resin having a melting point of 130°C or higher and 158°C or lower (i.e., a mid-melting point polypropylene-based resin). This improves laminate strength, thereby enabling the production of packaging bags with even better heat-seal strength. The mechanism by which laminate strength is improved is described below. Mid-melting point polypropylene-based resins have a lower melting point than the high-melting point polypropylene-based resins described below, and therefore tend to have a lower crystallinity than high-melting point polypropylene-based resins, and therefore tend to be more flexible than high-melting point polypropylene-based resins. When surface layer B contains a mid-melting point polypropylene-based resin, the flexibility of surface layer B can be improved. Therefore, when a heat-sealable film is laminated using an adhesive on the surface closer to surface layer B than surface layer C of both sides of the laminate according to an embodiment of the present invention and then the heat-sealable film is peeled off, the stress applied to surface layer B can be dispersed. This prevents peeling (i.e., interfacial failure) at the interface between the laminate and the adhesive layer from occurring too easily. That is, when the surface layer B contains a mid-melting point polypropylene resin, the laminate strength can be improved. When the surface layer C contains a mid-melting point polypropylene resin, the flexibility of the surface layer C can be improved. Therefore, when a heat-sealable film is laminated using an adhesive on the surface of the laminate according to an embodiment of the present invention that is closer to the surface layer C than the surface layer B, and then the heat-sealable film is peeled off, the stress applied to the surface layer C can be dispersed. Therefore, peeling at the interface between the laminate and the adhesive layer (i.e., interfacial fracture) can be prevented from occurring too easily. That is, when the surface layer C contains a mid-melting point polypropylene resin, the laminate strength can be improved.

[0032] The surface layer B and the surface layer C preferably contain 25% by mass or more and 85% by mass or less of a polypropylene-based resin having a melting point of 130° C. or more and 158° C. or less. The surface layer B and the surface layer C preferably contain 15% by mass or more and 75% by mass or less of a polypropylene-based resin having a melting point of 159° C. or more and 175° C. or less. On the other hand, the content of the polypropylene-based resin having a melting point of 129° C. or less in the surface layer B and the surface layer C is preferably low, specifically, preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, and most preferably 0% by mass (no polypropylene-based resin of 129° C. or less). In the following, the polypropylene resin having a melting point of 159°C or higher and 175°C or lower used in surface layer B and surface layer C may be referred to as a "high melting point polypropylene resin," the polypropylene resin having a melting point of 130°C or higher and 158°C or lower may be referred to as a "mid-melting point polypropylene resin," and the polypropylene resin having a melting point of 129°C or lower may be referred to as a "low melting point polypropylene resin." The melting points of the polypropylene resins used in surface layer B and surface layer C are rounded to one decimal place and are classified as high melting point polypropylene resin, mid-melting point polypropylene resin, or low melting point polypropylene resin. Only one type of high melting point polypropylene resin, mid-melting point polypropylene resin, and low melting point polypropylene resin may be used, or two or more different types of polypropylene resins may be used.

[0033] When the surface layer B and the surface layer C contain 25% by mass or more and 85% by mass or less of a mid-melting point polypropylene resin, adhesion to a printed layer, a vapor-deposited layer, a coating layer, etc. can be further improved. Increasing the adhesion of both the surface layer B and the surface layer C can dramatically increase the peel strength of a laminate obtained by laminating other components on both sides of a biaxially oriented polypropylene film. Having a melting point of 158°C or less of the mid-melting point polypropylene resin can improve adhesion to a functional layer. Having a melting point of 130°C or more can suppress roughening of the film surface even when the longitudinal stretching temperature is increased during film formation, and increasing the longitudinal stretching temperature can suppress detachment of the antiblocking agent. The mid-melting point polypropylene resin preferably has a melting point of 134°C or more and 150°C or less, more preferably 138°C or more and 143°C or less. Having a mid-melting point polypropylene resin content of 25% by mass or more can improve adhesion to a printed layer, a vapor-deposited layer, a coating layer, etc. By setting the content of the mid-melting point polypropylene resin to 85% by mass or less, productivity can be ensured during film production, and roughening of the film surface can be suppressed. Surface layer B and surface layer C more preferably contain 30% by mass or more and 80% by mass or less, and even more preferably 35% by mass or more and 75% by mass or less, of the mid-melting point polypropylene resin.

[0034] On the other hand, surface layer B and surface layer C preferably contain a high-melting-point polypropylene resin having a melting point higher than that of the mid-melting-point polypropylene resin in order to maintain the thermal dimensional stability and mechanical strength of the biaxially oriented polypropylene film. The high-melting-point polypropylene resin preferably has a melting point of 160°C or higher and 170°C or lower, and more preferably 161°C or higher and 165°C or lower. Furthermore, surface layer B and surface layer C preferably contain 15% by mass or higher and 75% by mass or lower, more preferably 20% by mass or higher and 70% by mass or lower, and even more preferably 25% by mass or higher and 65% by mass or lower, of the high-melting-point polypropylene resin.

[0035] With respect to the total resin contained in surface layer B and surface layer C, the total content of the high-melting point polypropylene resin and the mid-melting point polypropylene resin is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, even more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, particularly preferably 95 to 100 mass%, and most preferably 98 to 100 mass%. In other words, the total content of the high-melting point polypropylene resin and the mid-melting point polypropylene resin in surface layer B can be within the preferred range described herein. The total content of the high-melting point polypropylene resin and the mid-melting point polypropylene resin in surface layer C can also be within the preferred range described herein.

[0036] Various suitable physical properties of the mid-melting point polypropylene resin and the high-melting point polypropylene resin are described below. When two or more different polypropylene resins are used as the mid-melting point polypropylene resin, it is preferable that the mass-averaged values ​​of the physical properties of the respective polypropylene resins fall within the numerical ranges described below. When two or more different polypropylene resins are used as the high-melting point polypropylene resin, it is preferable that the mass-averaged values ​​of the physical properties of the respective polypropylene resins fall within the numerical ranges described below.

[0037] The melt flow rate (MFR; 230°C, 2.16 kgf) of the mid-melting point polypropylene resin is preferably 2.0 g / 10 min or more and 10 g / 10 min or less. It is even more preferably 3.0 g / 10 min or more and 8.0 g / 10 min or less, and even more preferably 4.0 g / 10 min or more and 7.0 g / 10 min or less. The melt flow rate (MFR; 230°C, 2.16 kgf) of the high-melting point polypropylene resin is preferably 2.0 g / 10 min or more and 10 g / 10 min or less, and more preferably 3.0 g / 10 min or more and 6.0 g / 10 min or less. The difference between the MFR of the mid-melting point polypropylene resin and the MFR of the high-melting point polypropylene resin is preferably 2.0 g / 10 min or less, and more preferably 1.5 g / 10 min or less.

[0038] The weight-average molecular weight (Mw) of the mid-melting point polypropylene resin is preferably 180,000 to 500,000. It is more preferably 190,000 to 320,000, even more preferably 200,000 to 300,000, and particularly preferably 230,000 to 260,000. If the Mw is less than 180,000, the melt viscosity is low, which may result in instability during casting and poor film formability. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less becomes too small, which may result in a reduced heat shrinkage rate at high temperatures.

[0039] The Mw of the high-melting-point polypropylene resin is preferably 180,000 to 500,000. It is more preferably 210,000 to 400,000, even more preferably 240,000 to 350,000, and particularly preferably 270,000 to 320,000. If the Mw is less than 180,000, the melt viscosity is low, which may result in instability during casting and poor film formability. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less becomes too small, which may result in a reduced heat shrinkage rate at high temperatures. It is also preferable that the Mw of the high-melting-point polypropylene resin be higher than that of the mid-melting-point polypropylene resin.

[0040] The number average molecular weight (Mn) of the mid-melting point polypropylene resin is preferably 20,000 to 200,000. It is more preferably 30,000 to 80,000, even more preferably 40,000 to 70,000, and particularly preferably 45,000 to 55,000. If Mn is less than 20,000, the melt viscosity is low, which may result in instability during casting and poor film formability. If Mn exceeds 200,000, the heat shrinkage at high temperatures may be reduced.

[0041] The Mn of the high-melting point polypropylene resin is preferably 20,000 to 200,000. It is more preferably 30,000 to 80,000, even more preferably 40,000 to 70,000, and particularly preferably 50,000 to 60,000. If the Mn is less than 20,000, the melt viscosity is low, which may result in instability during casting and poor film formability. If the Mn exceeds 200,000, the heat shrinkage rate at high temperatures may decrease. It is also preferable that the Mn of the high-melting point polypropylene resin is greater than the Mn of the mid-melting point polypropylene resin.

[0042] The molecular weight distribution (Mw / Mn) of the mid-melting point polypropylene resin is preferably 2.8 to 10, more preferably 3.2 to 9.0, even more preferably 3.5 to 9.0, particularly preferably 4.0 to 8.0, and most preferably 4.5 to 6.0. The molecular weight distribution (Mw / Mn) of the high-melting point polypropylene resin is preferably 2.8 to 10, more preferably 3.2 to 9.0, even more preferably 3.5 to 9.0, particularly preferably 3.7 to 8.0, and most preferably 4.0 to 6.0. It is also preferable that the Mw / Mn of the high-melting point polypropylene resin is larger than the Mw / Mn of the mid-melting point polypropylene resin.

[0043] High-melting point polypropylene resins, mid-melting point polypropylene resins, and low-melting point polypropylene resins can be obtained by polymerizing the raw material propylene using known catalysts such as Ziegler-Natta catalysts and metallocene catalysts. To obtain a mid-melting point polypropylene resin having a melting point of 130°C or higher and 158°C or lower, ethylene and / or an α-olefin having 4 or more carbon atoms may be copolymerized, or a polypropylene resin with reduced stereoregularity may be used depending on the catalyst used. Of course, a mid-melting point polypropylene resin can also be obtained without copolymerizing ethylene and / or an α-olefin having 4 or more carbon atoms. The content of α-olefin components other than propylene in the mid-melting point polypropylene resin (the total amount of ethylene and α-olefins having 4 or more carbon atoms) is preferably 0 to 15 mol %, more preferably 2 to 10 mol %.

[0044] The mid-melting point polypropylene resin is preferably a polypropylene resin copolymerized with ethylene and / or an α-olefin having 4 or more carbon atoms. This improves the laminate strength, thereby enabling the production of packaging bags with even greater heat-seal strength. The mechanism by which this improves the laminate strength is described below. When the surface layer B contains a polypropylene resin copolymerized with ethylene and / or an α-olefin having 4 or more carbon atoms, the flexibility of the surface layer B can be improved. Therefore, when a heat-sealable film is laminated using an adhesive on the surface of the laminate according to an embodiment of the present invention closer to the surface layer B than the surface layer C, and then the heat-sealable film is peeled off, the stress applied to the surface layer B can be dispersed. This prevents excessive peeling (i.e., interfacial fracture) at the interface between the laminate and the adhesive layer. In other words, when the surface layer B contains a polypropylene resin copolymerized with ethylene and / or an α-olefin having 4 or more carbon atoms, the laminate strength can be improved. When the surface layer C contains a polypropylene-based resin copolymerized with ethylene and / or an α-olefin having 4 or more carbon atoms, the flexibility of the surface layer C can be improved. Therefore, when a heat-sealable film is laminated using an adhesive onto the surface of the laminate according to an embodiment of the present invention that is closer to the surface layer C than the surface layer B, and then the heat-sealable film is peeled off, the stress applied to the surface layer C can be dispersed. Therefore, peeling at the interface between the laminate and the adhesive layer (i.e., interfacial fracture) can be prevented from occurring too easily. In other words, when the surface layer C contains a polypropylene-based resin copolymerized with ethylene and / or an α-olefin having 4 or more carbon atoms, the laminate strength can be improved.

[0045] From the viewpoint of imparting slip properties and anti-blocking properties to the surface layer B and the surface layer C, the surface layer B and the surface layer C preferably contain an anti-blocking agent. Furthermore, the surface layer B and / or the surface layer C may contain additives other than the anti-blocking agent or resins other than the polypropylene-based resin. Examples of other additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, inorganic or organic fillers, etc. Examples of other resins include polyolefin-based resins other than the polypropylene-based resin used in the surface layer B and / or the surface layer C, and various elastomers. These may be sequentially polymerized using a multi-stage reactor, blended with a polypropylene-based resin using a Henschel mixer, or master pellets prepared in advance using a melt kneader may be diluted with a polypropylene-based resin to a predetermined concentration, or the entire amount may be melt-kneaded in advance before use.

[0046] The antiblocking agent is preferably a particle having a pore volume of 0.2 mL / g to 3 mL / g, more preferably 0.5 mL / g to 2.5 mL / g, and even more preferably 1.1 mL / g to 1.8 mL / g. The antiblocking agent can be appropriately selected from inorganic and organic particles. Among these, silicon compounds are particularly preferred. Examples of silicon compounds include silica, silicates, and compounds having a main skeleton formed by siloxane bonds. Porous silica particles are particularly preferred. When porous silica is used, those having a pore volume of 0.8 mL / g to 2 mL / g are preferred, and those having a pore volume of 1.1 mL / g to 1.8 mL / g are more preferred. The particle shape may be spherical or irregular, with irregular shapes being preferred. The average particle size of the particles is preferably 1 μm to 5 μm, more preferably 2 μm to 4 μm. The average particle size is determined by taking a photograph using a scanning electron microscope, measuring the Feret's diameter in the horizontal direction using an image analyzer, and averaging the results. The use of the antiblocking agent is preferred in that it can reduce the rate at which the antiblocking agent falls off and suppress guide roll contamination.

[0047] The content of the antiblocking agent in the biaxially oriented polypropylene film is preferably 100 ppm to 10,000 ppm, more preferably 300 ppm to 6,000 ppm, even more preferably 800 ppm to 4,000 ppm, and particularly preferably 1,200 ppm to 2,700 ppm, based on the total mass of the surface layer B and / or surface layer C. By setting the content within the above range, the three-dimensional average roughness of the surface layer B and / or surface layer C can be set within the specified range described below. By setting the content of the antiblocking agent to 100 ppm or more, a film with excellent slip properties and blocking resistance can be obtained. By setting the content of the antiblocking agent to 10,000 ppm or less, shedding of the antiblocking agent can be reduced, thereby suppressing guide roll contamination. Furthermore, if there is a decrease in light transmittance, if the antiblocking agent penetrates the functional layer when the functional layer is laminated, or if there is antiblocking agent that protrudes from surface layer B and / or surface layer C, the functional layer (the functional layer formed in the vicinity of surface layer B and / or surface layer C) is unlikely to become sparse due to the antiblocking agent, and a decrease in barrier performance or poor adhesion due to the sparseness of the functional layer is unlikely to occur.

[0048] The content of the antiblocking agent in the surface layer B is preferably 100 ppm or more and 10,000 ppm or less, more preferably 300 ppm or more and 6,000 ppm or less, even more preferably 800 ppm or more and 4,000 ppm or less, and particularly preferably 1,200 ppm or more and 2,700 ppm or less, based on the total mass of the surface layer B. By setting the content within the above range, the three-dimensional average roughness of the surface layer B can be set within the specified range described below. By setting the content of the antiblocking agent to 100 ppm or more, a film with excellent slip properties and blocking resistance can be obtained. By setting the content of the antiblocking agent to 10,000 ppm or less, shedding of the antiblocking agent can be reduced, thereby suppressing guide roll contamination. Furthermore, if there is a decrease in light transmittance or if the antiblocking agent penetrates the functional layer when laminating the functional layer, or if there is antiblocking agent protruding from surface layer B, the antiblocking agent is less likely to cause the functional layer (i.e., the functional layer formed in the vicinity of surface layer B) to become sparse, and a decrease in barrier performance or poor adhesion due to the sparseness of the functional layer is less likely to occur. The description of the content of the antiblocking agent in surface layer C will be omitted because it overlaps with the description of the content of the antiblocking agent in surface layer B. Therefore, the description of the content of the antiblocking agent in surface layer B can also be used as a description of the content of the antiblocking agent in surface layer C.

[0049] [Layer structure and thickness structure of biaxially oriented polypropylene film] The biaxially oriented polypropylene film has a surface layer B on one side of the base layer A. The surface layer B may be directly laminated on the surface of the base layer A, or another layer may be interposed between the base layer A and the surface layer B. The biaxially oriented polypropylene film also has a surface layer C on the other side of the base layer A. The surface layer C may be directly laminated on the surface of the base layer A, or another layer may be interposed between the base layer A and the surface layer C. For example, the biaxially oriented polypropylene film may have a three-layer structure consisting of only the surface layer B / base layer A / surface layer C, or may have a multi-layer structure of four or more layers including layers other than the base layer A, surface layer B, and surface layer C. An example of a four-layer structure is surface layer B / intermediate layer D / base layer A / surface layer C, and an example of a five-layer structure is surface layer B / intermediate layer D / base layer A / intermediate layer D / surface layer C. By providing the intermediate layer D, the adhesive strength between the base layer A and the surface layer B and / or surface layer C can be increased.

[0050] The thickness of the biaxially oriented polypropylene film is preferably 5 to 100 μm, more preferably 10 to 80 μm, and even more preferably 18 to 50 μm. If the thickness is within the above range, the film has sufficient rigidity and is suitable as a substrate for packaging and industrial use.

[0051] The thickness of each of surface layer B and surface layer C is preferably 0.3 μm to 10 μm, more preferably 0.5 μm to 3 μm, and even more preferably 0.8 μm to 2 μm. A thickness of 0.3 μm or more can improve the adhesion between surface layer B and surface layer C and the functional layer, making the film suitable for use as a substrate for packaging or industrial applications that require the addition of a functional layer, such as through vapor deposition or coating. If the thickness of surface layer B is greater than 10 μm, the thickness ratio of substrate layer A may become relatively low, which may result in a decrease in the rigidity and thermal dimensional stability of the film.

[0052] The thickness of the base layer A is preferably 5 to 90 μm, more preferably 10 to 50 μm, and even more preferably 15 to 30 μm. A thickness of 5 μm or more can improve the thermal dimensional stability and mechanical strength of the film. If the thickness of the base layer A is greater than 90 μm, the thermal dimensional stability and mechanical strength can be improved, but there is a risk that these effects will saturate.

[0053] [Method for producing biaxially oriented polypropylene film] The biaxially oriented polypropylene film can be obtained by melt-extruding the polypropylene resin compositions constituting each of the base layer A, surface layer B, and surface layer C using separate extruders, co-extruding them through a die, and cooling them with a cooling roll to form an unstretched sheet, stretching the unstretched sheet in the longitudinal direction (MD) and width direction (TD), and then heat-setting the sheet.

[0054] The melt extrusion temperature is preferably about 200 to 280°C. When the base layer A, surface layer B, and surface layer C are co-extruded within this temperature range, in order to obtain a film with good appearance without layer disorder, it is preferable that the difference between the MFR of the base layer A and the MFR of the surface layer B and surface layer C (hereinafter referred to as the MFR difference) is 5.0 g / 10 min or less. That is, it is preferable that the difference between the MFR of the base layer A and the MFR of the surface layer B (hereinafter referred to as the first MFR difference) is 5.0 g / 10 min or less, and that the difference between the MFR of the base layer A and the MFR of the surface layer C (hereinafter referred to as the second MFR difference) is 5.0 g / 10 min or less. If the MFR difference is greater than 5.0 g / 10 min, the layers are likely to be disordered, resulting in poor appearance. The difference is more preferably 4.0 g / 10 min or less, and even more preferably 3.0 g / 10 min or less. The difference between the maximum MFR and the minimum MFR among the three polypropylene resin compositions constituting the base layer A, the surface layer B, and the surface layer C is preferably 5.0 g / 10 min or less, and more preferably 3.0 g / 10 min or less.

[0055] The surface temperature of the chill roll is preferably 20 to 50°C, more preferably 30 to 40°C. When the chill roll temperature is 50°C or less, crystallization of the unstretched sheet and growth of spherulites can be suppressed, allowing for a high stretch ratio and producing a film with a high tensile modulus. In addition, the occurrence of large surface irregularities due to spherulites can be suppressed, producing a film with an appropriate surface roughness.

[0056] The lower limit of the stretching ratio in the longitudinal direction (MD) is preferably 3.5 times or more, more preferably 4 times or more. If it is 3.5 times or more, thickness unevenness can be reduced. The upper limit of the stretching ratio in the MD is preferably 8 times or less, more preferably 7 times or less. If it is 8 times or less, breakage is less likely to occur in the subsequent TD stretching, making production easier.

[0057] The lower limit of the MD stretching temperature is preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 135°C or higher. At 120°C or higher, thickness unevenness is less likely to increase and the film surface is less likely to become rough. A higher MD stretching temperature makes it less likely that voids will be formed around the antiblocking agent particles, preventing roll contamination during processing due to the antiblocking agent particles falling off the film surface. Furthermore, good gas barrier properties are obtained when aluminum is vapor-deposited.

[0058] The upper limit of the MD stretching temperature is preferably 150°C or less, more preferably 145°C or less, and even more preferably 140°C or less. If the MD stretching temperature is too high, the film may start to stick to the MD stretching rolls, causing stick-slip and resulting in spots and surface roughness on the film. Furthermore, if the MD stretching temperature is too high, the film may stick to the stretching rolls, making it impossible to stretch.

[0059] The lower limit of the stretching ratio in the transverse direction (TD) is preferably 6 times or more, more preferably 7 times or more, and even more preferably 8 times or more. If it is 6 times or more, thickness unevenness is unlikely to become large. The upper limit of the TD stretching ratio is preferably 15 times or less, more preferably 13 times or less, and even more preferably 11 times or less. If it exceeds the above range, the heat shrinkage rate may become high and there is a risk of frequent breakage during stretching.

[0060] It is preferable to heat the uniaxially stretched film after longitudinal stretching to sufficiently soften the polypropylene resin composition before the widthwise stretching step. The heating temperature in the preheating step is preferably 160°C or higher and 180°C or lower, and more preferably 165°C or higher and 175°C or lower. By setting the heating temperature in the preheating step to 160°C or higher, softening progresses and widthwise stretching becomes easier. The lower limit of the TD stretching temperature is preferably 150°C or higher, more preferably 152°C or higher, even more preferably 154°C or higher, and particularly preferably 156°C or higher. At 150°C or higher, the film is easily softened sufficiently, and is less likely to break or have an increased heat shrinkage rate. The upper limit of the TD stretching temperature is preferably 170°C or lower, more preferably 168°C or lower, and even more preferably 166°C or lower.

[0061] To reduce the heat shrinkage rate, a higher heat setting temperature is preferred, more preferably 160°C or higher, and even more preferably 162°C or higher. If the temperature is 160°C or higher, the heat shrinkage rate is less likely to increase. The upper limit of the heat setting temperature is preferably 180°C or lower, more preferably 175°C or lower. If the temperature is 180°C or lower, surface roughening and whitening of the film are less likely to occur.

[0062] It is preferable to relax the film during heat setting. The lower limit of the relaxation rate is preferably 2% or more, more preferably 3% or more, and even more preferably 5% or more. If it is 2% or more, the thermal shrinkage rate is unlikely to become high. The upper limit of the relaxation rate is preferably 10% or less, more preferably 8% or less. If it is 10% or less, thickness unevenness is unlikely to become large.

[0063] Furthermore, in order to reduce the thermal shrinkage rate, the film produced by the above process may be wound into a roll and then annealed offline.

[0064] The film thus obtained may be subjected to corona discharge, plasma treatment, flame treatment, etc., as required, and then wound up with a winder to obtain a biaxially oriented polypropylene film roll. Note that the method for producing the biaxially oriented polypropylene film is not limited to the above-mentioned method.

[0065] [Various properties of biaxially oriented polypropylene film] (Haze) The haze of the biaxially oriented polypropylene film is preferably 8% or less, more preferably 5% or less, even more preferably 4% or less, and particularly preferably 3% or less. A haze within the above range makes it easy to use in applications requiring transparency. Haze tends to deteriorate when the stretching temperature or heat setting temperature is too high, when the cooling roll temperature is high and the cooling rate of the unstretched (raw) sheet is slow, or when there is too much low-molecular-weight component with a molecular weight of 100,000 or less. By adjusting these conditions, the haze can be kept within the above range.

[0066] (Tensile Modulus) The tensile modulus of the biaxially oriented polypropylene film in the longitudinal direction is preferably 1.0 GPa or more, more preferably 1.5 GPa or more, even more preferably 1.8 GPa or more, and particularly preferably 2.0 GPa or more. There is no particular upper limit, and it is, for example, 5.0 GPa or less. The tensile modulus of the biaxially oriented polypropylene film in the width direction is preferably 3.0 GPa or more, more preferably 3.2 GPa or more, and even more preferably 3.5 GPa or more. There is no particular upper limit, and it is, for example, 10 GPa or less. The sum of the tensile modulus of the biaxially oriented polypropylene film in the longitudinal direction and the width direction is preferably 5.8 to 12.0 Pa, and more preferably 6.0 to 10.0 GPa. When the tensile modulus is within the above range, the film has strong stiffness, can be used even with a thin film thickness, and ultimately can reduce costs. In addition, the "longitudinal direction" of a biaxially oriented polypropylene film refers to the flow direction in the film production process, i.e., the direction corresponding to the machine direction (MD), and the "width direction" refers to the direction perpendicular to the flow direction in the film production process, i.e., the transverse direction (TD), and the same applies hereinafter.

[0067] (Heat Shrinkage Rate) The heat shrinkage rate of the biaxially oriented polypropylene film in the longitudinal direction at 150°C is 10.0% or less, preferably 9.0% or less, more preferably 7.0% or less, and even more preferably 5.0% or less. Within the above range, the film can be used in applications where it may be exposed to high temperatures. Furthermore, even when a functional layer is laminated on the film, the degradation of the barrier property of the functional layer can be suppressed, thereby improving the barrier property of the laminate. Because the heat shrinkage rate is 10.0% or less, when a packaging bag having a heat-sealed portion is produced using the laminate according to an embodiment of the present invention, excessive wrinkling of the heat-sealed portion due to the heat applied to the laminate by heat sealing can be prevented or reduced. Therefore, a packaging bag with an excellent appearance at the heat-sealed portion can be produced. The lower limit of the heat shrinkage rate of the biaxially oriented polypropylene film of the present invention in the longitudinal direction at 150°C is preferably 0.0%. From the viewpoint of productivity in production, the heat shrinkage rate is preferably 1% or more, more preferably 3% or more. The heat shrinkage rate in the width direction of the biaxially oriented polypropylene film at 150°C is 15.0% or less, more preferably 10.0% or less, even more preferably 8.0% or less, and particularly preferably 5% or less. Because it is 15.0% or less, when a packaging bag having a heat-sealed portion is produced using the laminate according to an embodiment of the present invention, excessive wrinkling in the heat-sealed portion due to the heat applied to the laminate by heat sealing can be further prevented or reduced. Therefore, a packaging bag with an even better appearance in the heat-sealed portion can be produced. The lower limit of the heat shrinkage rate in the width direction at 150°C is preferably 0.0%. From the perspective of production productivity, the lower limit is preferably 3%, more preferably 5%. Within the above range, the film can be used in applications where it may be exposed to high temperatures. Furthermore, even when a functional layer is laminated on the film, the degradation of the barrier property of the functional layer can be suppressed, thereby improving the barrier property of the laminate. The sum of the heat shrinkage rates in the longitudinal and width directions of the biaxially oriented polypropylene film at 150°C is preferably 25.0% or less, more preferably 23.0% or less, even more preferably 20.0% or less, even more preferably 15.0% or less, and particularly preferably 12.0% or less. The lower limit of the sum of the heat shrinkage rates in the longitudinal and width directions at 150°C is 0% or more. If the film is in the above range, it can be used in applications where it may be exposed to high temperatures.Furthermore, even when a functional layer is laminated on the film, the degradation of the barrier properties of the functional layer can be suppressed, and as a result, the barrier properties of the laminate can be improved.

[0068] (Three-dimensional average roughness) The lower limit of the three-dimensional average roughness SRa of the surface layer B and / or surface layer C of the biaxially oriented polypropylene film of the present invention is 15 nm. It is preferably 20 nm, more preferably 25 nm, and even more preferably 30 nm. When the three-dimensional average roughness of the surface layer B and / or surface layer C is 15 nm or more, the film has good slipperiness and can suppress the occurrence of wrinkles when wound into a roll or during post-processing such as vapor deposition. Furthermore, the upper limit of the three-dimensional average roughness of the surface layer B and / or surface layer C is preferably 100 nm. When it is 100 nm or less, the film has good transparency and can suppress the film from becoming too slippery when wound into a roll or during post-processing such as vapor deposition, thereby preventing deterioration of workability. The three-dimensional average roughness SRa can be controlled by adjusting the type, particle size, amount, and film-forming conditions of the antiblocking agent. When imparting gas barrier properties to a biaxially oriented polypropylene film by vapor deposition, the gas barrier properties of the vapor-deposited layer can be improved by making the surface protrusions on the surface to be vapor-deposited small and smooth, and the surface protrusions on the other surface can be made large to impart slip properties and anti-blocking properties. In this case, the three-dimensional average roughness SRa of the surface to be vapor-deposited can be less than 15 nm.

[0069] (Antiblocking Agent Dropout Rate) The dropout rate of the antiblocking agent in each of surface layer B and surface layer C is 10% or less, preferably 8% or less, more preferably 6% or less, and even more preferably 4% or less. A dropout rate of 10% or less can prevent or reduce excessive contamination of the guide roll with the antiblocking agent when slitting the biaxially oriented polypropylene film. Contamination of the guide roll during post-processing such as coating or vapor deposition can also be suppressed. Furthermore, the generation of voids due to dropout of the antiblocking agent can be suppressed, and a laminate with excellent gas barrier properties can be obtained when metal and / or metal oxide is vapor-deposited. The lower limit of the dropout rate is not particularly limited, but is, for example, 0.3% or more. The dropout rate of the antiblocking agent can be adjusted to the above range by adjusting the film-forming conditions in addition to the type, pore volume, particle size, and content of the antiblocking agent.

[0070] (Wet Tension) The surface wet tension of the surface layer B and / or surface layer C of the biaxially oriented polypropylene film is preferably 36 mN / m or more, more preferably 38 mN / m or more, and more preferably 40 mN / m or more. The wet tension may be appropriately set depending on the type of functional layer to be formed on the surface layer B and / or surface layer C. When an inorganic thin film layer such as an aluminum thin film layer is formed by a thermal vapor deposition method or the like, setting the surface to 36 mN / m or more tends to improve adhesion with the inorganic vapor deposition layer. Similarly, when a heat-sealable film is bonded to the surface layer B and / or surface layer C, the wet tension may be appropriately set depending on the type of adhesive used for bonding, but setting the wet tension to 36 mN / m or more tends to improve adhesion. To achieve a wet tension of 36 mN / m or more, surface treatments such as corona treatment, flame treatment, and anchor coating treatment can be performed. Since too high a wet tension can deteriorate slip properties and anti-blocking properties, it is preferable that the wet tension be 46 mN / m or less.

[0071] (Surface Resistivity) The surface resistance of the surface layer B and / or surface layer C of the biaxially oriented polypropylene film is preferably 14 Log Ω or more, more preferably 14.5 Log Ω or more, and even more preferably 15 Log Ω or more. If the film contains additives or impurities such as antistatic agents, they may bleed out to the film surface due to surface treatment, resulting in poor adhesion. A surface resistance of 14 Log Ω or more reduces bleed-out of additives and the like to the film surface, which is preferable in terms of adhesion to the functional layer. The preferred upper limit of the surface resistance of the surface layer B and / or surface layer C is not particularly limited, but is 18 Log Ω or less from a manufacturing perspective.

[0072] (Dynamic Friction Coefficient) The dynamic friction coefficient of the biaxially oriented polypropylene film is preferably 0.5 or less, more preferably 0.48 or less, and particularly preferably 0.45 or less. A dynamic friction coefficient of 0.5 or less allows the film to be smoothly unwound from a roll film, facilitating printing processing. The dynamic friction coefficient of the biaxially oriented polypropylene film can be adjusted by the raw material composition and film-forming conditions. In particular, it can be adjusted by the amount and particle size of the antiblocking agent blended in surface layer B and surface layer C. It is preferable that the lower limit of the three-dimensional average roughness SRa of surface layer B and / or surface layer C is 15 nm.

[0073] [Gas Barrier Layer] The laminate according to the embodiment of the present invention includes a gas barrier layer. The gas barrier layer is preferably either a coating layer D containing an organic substance as a main component, or an inorganic thin film layer E containing an inorganic substance as a main component. These will be described later. Furthermore, in order to enhance the barrier properties of the gas barrier layer, an anchor coat layer F or a protective layer G, which will be described later, can also be used in combination.

[0074] [Coating Layer D] The laminate according to the embodiment of the present invention may have a coating layer D as a gas barrier layer. However, it is desirable to design the laminate with due consideration given to the environmental impact of providing the coating layer D, such as increased costs due to the additional steps and difficulty in recycling depending on the film thickness.

[0075] The coating weight of the coating layer D is 0.10 to 3.0 (g / m ２The lower limit of the amount of coating layer D is preferably 0.15 (g / m ２ ) or more, more preferably 0.20 (g / m ２ ) or more, more preferably 0.25 (g / m ２ ) or more, and the upper limit is preferably 2.5 (g / m ２ ) or less, more preferably 2.0 (g / m ２ ) or less, more preferably 1.5 (g / m ２ The coating weight of the coating layer D is 3.0 (g / m ２ ), the gas barrier properties improve, but the cohesive force inside the coating layer becomes insufficient and the uniformity of the coating layer also decreases, which can cause unevenness (increased haze, whitening) or defects in the coat appearance, or can prevent the gas barrier properties and adhesive properties from being fully exhibited. In terms of processability, a thick film thickness can also cause blocking. Furthermore, there is a concern that this will have a negative effect on the recyclability of the film, and the amount of raw materials, solvents, etc. used will increase, which will increase the environmental impact. On the other hand, if the coating layer D adhesion amount is 0.10 (g / m ２ If the thickness is less than 1 / 2 mm, sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0076] The resin used for the coating layer D is preferably a polyvinyl alcohol polymer, a polyester resin, or a polyurethane resin. Among these, polyvinyl alcohol polymers are more preferred from the perspective of improving barrier performance. Polyvinyl alcohol polymers are primarily composed of vinyl alcohol units, and are expected to significantly improve barrier performance due to their high cohesion caused by a hydrogen-bonded structure. The polymerization degree and saponification degree of the polyvinyl alcohol polymer are determined based on the desired gas barrier properties and the viscosity of the coating solution. The high viscosity of the aqueous solution and its tendency to gel make coating difficult, so a polymerization degree of 2600 or less is preferred from the perspective of coating workability. A saponification degree of less than 90% does not provide sufficient oxygen barrier properties under high humidity conditions, while a saponification degree of more than 99.7% makes it difficult to prepare the aqueous solution, is prone to gelation, and is not suitable for industrial production. Therefore, a saponification degree of 90 to 99.7% is preferred, and a saponification degree of 93 to 99% is even more preferred. In the present invention, various copolymerized or modified polyvinyl alcohol-based polymers, such as polyvinyl alcohol-based polymers copolymerized with ethylene and silanol-modified polyvinyl alcohol-based polymers, can also be used within the scope of not impairing processability or productivity.

[0077] The coating layer D may contain an inorganic layered compound. The presence of the inorganic layered compound can be expected to provide a labyrinth effect against gases, improving gas barrier properties. Furthermore, the addition of the inorganic layered compound can suppress humidity dependency of gas barrier properties. Examples of materials include clay minerals (including synthetic products thereof) such as smectite, kaolin, mica, hydrotalcite, and chlorite. Specific examples include montmorillonite, beidellite, saponite, hectorite, sauconite, stevensite, kaolinite, nacrite, dickite, halloysite, hydrated halloysite, tetrasilylic mica, sodium taeniolite, muscovite, margarite, phlogopite, talc, antigorite, chrysotile, pyrophyllite, vermiculite, xanthophyllite, and chlorite. Furthermore, scaly silica and the like can also be used as the inorganic layered compound. These may be used alone or in combination of two or more. Among these, smectite (including synthetic products thereof) is particularly preferred because it has a high effect of improving the water vapor barrier property.

[0078] Furthermore, inorganic layered compounds containing metal ions, particularly iron ions, having redox properties are preferred. Among these, montmorillonite, a type of smectite, is preferred from the viewpoint of coating suitability and gas barrier properties. As montmorillonite, known compounds that have been conventionally used in gas barrier agents can be used. For example, compounds represented by the following general formula: (X, Y) 2～3 Z4O 10 (OH)mHO(Wω) (In the formula, X represents Al, Fe(III), or Cr(III). Y represents Mg, Fe(II), Mn(II), Ni, Zn, or Li. Z represents Si or Al. W represents K, Na, or Ca. HO represents interlayer water. m and ω represent positive real numbers.) Among these, those in which W in the formula is Na are preferred because they cleave in an aqueous medium.

[0079] The size and shape of the inorganic layered compound are not particularly limited, but the particle size (major axis) is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. If the particle size is larger than 5 μm, dispersibility will be poor, which may result in deterioration of the coatability and coat appearance of the coating layer D. On the other hand, the aspect ratio is 50 to 5000, more preferably 100 to 4000, and even more preferably 200 to 3000.

[0080] The blending ratio of the resin to the inorganic layered compound in the coating layer D is preferably 75 / 25 to 35 / 65 (wt%), more preferably 70 / 30 to 40 / 60 (wt%), and even more preferably 65 / 35 to 45 / 55 (wt%). If the blending ratio of the inorganic layered compound is less than 25%, the barrier performance may be insufficient. On the other hand, if it is more than 65%, the dispersibility may be poor, which may result in poor coatability and poor adhesion.

[0081] In order to improve the cohesive strength of the film and the heat and moisture resistant adhesion, various crosslinking agents may be blended into the coating layer D within a range that does not impair gas barrier properties or productivity. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, isocyanate compounds, etc. Among these, the incorporation of a silicon-based crosslinking agent allows a crosslinking reaction to occur with a resin having a hydroxyl group or an inorganic thin film layer, and silicon-based crosslinking agents are particularly preferred from the viewpoint of improving water-resistant adhesion. Commonly used silicon-based crosslinking agents include metal alkoxides and silane coupling agents. Metal alkoxides are represented by the general formula M(OR)n (M: metals such as Si and Al, R: CH ３ , C ２ H ５ Specifically, tetraethoxysilane [Si(OC ２ H ５ ) ４ ], triisopropoxyaluminum Al[OCH(CH ３ ) ２ ] ３Examples of silane coupling agents include those having an epoxy group such as 3-glycidoxypropyltrimethoxysilane, those having an amino group such as 3-aminopropyltrimethoxysilane, those having a mercapto group such as 3-mercaptopropyltrimethoxysilane, those having an isocyanate group such as 3-isocyanatepropyltriethoxysilane, and tris-(3-trimethoxysilylpropyl)isocyanurate. In addition, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc. may be used in combination as crosslinking agents. However, when emphasis is placed on recyclability, the amount of crosslinking agent added must be considered.

[0082] When a crosslinking agent is incorporated, its amount in the coating layer D is preferably 0.1 to 50% by mass, more preferably 0.5 to 55% by mass, and even more preferably 1.0 to 50% by mass. By adjusting the amount within the above range, the film hardens and the cohesive strength improves, resulting in a film with excellent water-resistant adhesion. If the amount exceeds 50% by mass, the amount of uncrosslinked portions increases, or the film hardens due to excessive hardening, which may conversely result in a decrease in adhesion. On the other hand, if the amount is less than 0.1% by mass, sufficient cohesive strength may not be obtained.

[0083] From the viewpoint of visibility of the contents, the film haze after lamination of the coating layer D is preferably 20% or less, more preferably 18% or less, and even more preferably 16% or less. If the haze is greater than 20%, transparency will be significantly reduced and there is a concern that it will affect the surface irregularities, which may lead to poor appearance in subsequent printing processes, etc. The haze can be adjusted by the composition ratio of the coating layer D, solvent conditions, film thickness, etc. Here, the haze is evaluated in accordance with JIS K7136 using a turbidity meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.).

[0084] The coating method for the resin composition for the coating layer is not particularly limited as long as it is a method that can coat the surface of a film to form a layer, and for example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0085] When forming the coating layer D, it is preferable to apply the resin composition for the coating layer, pre-dry it at a relatively low temperature to volatilize the solvent, and then perform main drying at a high temperature, since this results in a uniform film. The pre-drying temperature is preferably 80 to 110°C, more preferably 85 to 105°C, and even more preferably 90 to 100°C. If the pre-drying temperature is less than 80°C, the coating layer D may not be sufficiently dried. If the pre-drying temperature is higher than 110°C, drying may proceed before the coating layer D has spread, resulting in a poor appearance.

[0086] On the other hand, the main drying temperature is preferably 110 to 140°C, more preferably 115 to 135°C, and even more preferably 120 to 130°C. If the main drying temperature is less than 110°C, film formation of the coating layer D does not proceed, resulting in a decrease in cohesive strength and adhesiveness, which may adversely affect the barrier properties. If the temperature exceeds 140°C, the film may be subjected to too much heat, making it brittle and causing large wrinkles due to heat shrinkage.

[0087] The preferred drying time for preliminary drying is 3.0 to 10.0 seconds, more preferably 3.5 to 9.5 seconds, and even more preferably 4.0 to 9.0 seconds. The preferred drying time for main drying is 3.0 to 10.0 seconds, more preferably 3.5 to 9.5 seconds, and even more preferably 4.0 to 9.0 seconds. However, caution is advised as drying conditions vary depending on the type of heat transfer medium and the intake and exhaust conditions of the drying furnace. Furthermore, additional heat treatment for 1 to 4 days at a temperature as low as possible, specifically 40 to 60°C, separate from drying, is also more effective in accelerating the formation of coating layer D.

[0088] [Inorganic Thin Film Layer E] The laminate according to the embodiment of the present invention may have an inorganic thin film layer E. The inorganic thin film layer E may be a thin film made of a metal or an inorganic oxide. There are no particular limitations on the material forming the inorganic thin film layer as long as it can be formed into a thin film. However, from the viewpoint of gas barrier properties, preferred examples include metals such as aluminum, and inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and mixtures of silicon oxide and aluminum oxide. In particular, complex oxides of silicon oxide and aluminum oxide are preferred from the viewpoint of achieving both flexibility and density of the thin film layer. In this complex oxide, the mixing ratio of silicon oxide to aluminum oxide is preferably in the range of 20 to 70 mass% Al in terms of the mass ratio of the metal components. If the Al concentration is less than 20 mass%, the water vapor barrier properties may be reduced. On the other hand, if the Al concentration exceeds 70 mass%, the inorganic thin film layer tends to become hard, and there is a risk that the film will be destroyed during secondary processing such as printing or lamination, resulting in a reduction in gas barrier properties. Note that silicon oxide as referred to here refers to SiO or SiO ２ and various silicon oxides such as AlO and Al ２ O ３ and the like, or mixtures thereof.

[0089] The thickness of the inorganic thin film layer E is usually 1 to 100 nm, preferably 5 to 95 nm, and more preferably 7 to 90 nm. If the thickness of the inorganic thin film layer E is less than 1 nm, it may be difficult to obtain satisfactory gas barrier properties. On the other hand, even if the thickness is excessively large, exceeding 100 nm, the corresponding improvement in gas barrier properties cannot be obtained and is actually disadvantageous in terms of flex resistance and production costs.

[0090] The method for forming the inorganic thin film layer E is not particularly limited, and any known vapor deposition method may be appropriately employed, such as a physical vapor deposition method (PVD method) such as vacuum deposition, sputtering, or ion plating, or a chemical vapor deposition method (CVD method). A typical method for forming the inorganic thin film layer E will be described below using a silicon oxide / aluminum oxide thin film as an example. For example, when the vacuum deposition method is employed, SiO ２ and Al ２ O ３ or a mixture of SiO２ A mixture of Al and Al is preferably used. These deposition materials are typically particles, and the particle size is preferably large enough to prevent pressure changes during deposition, with a preferred particle diameter of 1 mm to 5 mm. Heating can be performed using methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating. It is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, or other reactive gases as reactive gases, or to employ reactive deposition using ozone addition or ion-assisted deposition. Furthermore, film formation conditions can be freely modified, such as by applying a bias to the deposition target (the film to be deposited) or by heating or cooling the deposition target. The deposition materials, reactive gases, bias, heating, and cooling of the deposition target can be similarly modified when using sputtering or CVD.

[0091] When metal or inorganic oxide is vapor deposited, it is preferred to vapor deposit it on the side of the biaxially oriented polypropylene film according to an embodiment of the present invention that has less surface roughness.

[0092] [Anchor Coat Layer F] In an embodiment of the present invention, an anchor coat layer F may be provided as an auxiliary layer to provide sufficient gas barrier properties and adhesiveness when the aforementioned gas barrier layer is laminated. The presence of an anchor coat layer can suppress the exposure of oligomers and antiblocking agents from the polypropylene-based resin. Furthermore, when laminating other layers on the anchor coat layer F, it can also enhance interlayer adhesion. In particular, when forming an inorganic thin film layer, not only adhesion is enhanced, but surface smoothing can also be expected to promote the formation of the inorganic thin film layer and improve gas barrier properties. Additionally, by using a material with a certain level of gas barrier properties (hereinafter referred to as gas barrier auxiliary properties) for the anchor coat layer F itself, the gas barrier performance of the film when the aforementioned gas barrier layer is laminated can be significantly improved. Furthermore, the anchor coat layer F prevents hot water from penetrating the substrate, thereby reducing film whitening after boiling or retorting.

[0093] When only the anchor coat layer F is laminated on the biaxially oriented polypropylene film according to an embodiment of the present invention, the oxygen permeability is 10,000 ml / m under an environment of 23°C x 65% RH. ２ It is preferable that the viscosity is 9000 ml / m or less, since good gas barrier properties are exhibited after laminating the gas barrier layer. ２ d MPa or less, more preferably 8000 ml / m ２ ・d・MPa or less. Oxygen permeability is 10,000 ml / m ２ If the modulus exceeds d·MPa, sufficient barrier performance cannot be obtained even after laminating the gas barrier layer, and it may become difficult to use the film in applications that require high gas barrier properties.

[0094] In an embodiment of the present invention, the amount of the anchor coat layer F is 0.10 to 1.0 g / m ２ This allows the anchor coat layer F to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. Furthermore, the anchor coat layer F contributes to suppressing oligomer exposure, stabilizing haze after retort moist heat treatment. The amount of anchor coat layer F attached is preferably 0.15 g / m ２ More preferably, 0.20 g / m ２ More preferably, 0.35 g / m ２ or more, and preferably 0.950 g / m ２ or less, more preferably 0.90 g / m ２ More preferably 0.85 g / m or less ２ The adhesion amount of the anchor coat layer F is 1.0 g / m or less. ２ If the thickness exceeds 0.10 g / m, the gas barrier assisting property will improve, but the cohesive force inside the anchor coat layer will be insufficient and the uniformity of the anchor coat layer F will also decrease, resulting in unevenness and defects in the coat appearance. In terms of processability, a thick film thickness may cause blocking or increase manufacturing costs. Furthermore, there is a concern that it may have a negative effect on the recyclability of the film, and the amount of raw materials, solvents, etc. used will increase, which will increase the environmental impact. On the other hand, if the thickness of the anchor coat layer F is 0.10 g / m, ２If it is less than this, there is a risk that sufficient gas barrier assisting properties and interlayer adhesion may not be obtained.

[0095] Resin compositions used for the anchor coat layer F include those containing urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based, or other resins to which epoxy-based, isocyanate-based, or melamine-based curing agents have been added. Furthermore, crosslinking agents such as silicon-based crosslinkers, oxazoline compounds, carbodiimide compounds, and epoxy compounds may be included. The inclusion of a urethane resin is particularly preferred because, in addition to the barrier performance due to the high cohesiveness of the urethane bond itself, the polar groups interact with the gas barrier layer, and the presence of amorphous portions provides flexibility, thereby reducing damage even when subjected to bending loads. Polyester resins are also suitable, as they are expected to have similar effects. In embodiments of the present invention, it is particularly preferred to contain a polyurethane containing polyester and isocyanate as constituent components. Furthermore, the addition of a silicon-based crosslinker is even more preferred from the viewpoint of improving adhesion.

[0096] From the viewpoint of gas barrier assisting properties, it is more preferable to use a urethane resin containing an aromatic or araliphatic diisocyanate component as a main constituent component for the anchor coat layer F. Among these, a urethane resin containing a metaxylylene diisocyanate component is particularly preferable. By using such a resin, the cohesive strength of the urethane bond can be further increased due to the stacking effect between aromatic rings, resulting in good gas barrier assisting properties.

[0097] The proportion of aromatic or araliphatic diisocyanate in the urethane resin used in the anchor coat layer F is preferably 50 mol % or more (50 to 100 mol %) relative to 100 mol % of the polyisocyanate component. The total proportion of aromatic or araliphatic diisocyanate is preferably 60 to 100 mol %, more preferably 70 to 100 mol %, and even more preferably 80 to 100 mol %. If the total proportion of aromatic or araliphatic diisocyanate is less than 50 mol %, good gas barrier assist properties may not be obtained.

[0098] The urethane resin used in the anchor coat layer F may be blended with various crosslinking agents for the purpose of improving the cohesive strength of the film and improving the wet heat resistance adhesion. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc. Among these, silicon-based crosslinking agents are particularly preferred from the viewpoint that blending a silicon-based crosslinking agent can improve the water-resistant adhesion, particularly with the inorganic thin film layer. Other crosslinking agents such as oxazoline compounds, carbodiimide compounds, and epoxy compounds may also be used in combination.

[0099] As the silicon-based crosslinking agent, a silane coupling agent is preferred from the viewpoint of crosslinking between an inorganic substance and an organic substance. Examples of the silane coupling agent include hydrolyzable alkoxysilane compounds, such as halogen-containing alkoxysilanes (chloro C2-4 alkyl tri C1-4 alkoxysilanes such as 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, and 3-chloropropyltriethoxysilane), and alkoxysilanes having an epoxy group (2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, and the like). trimethoxysilane, glycidyloxy C2-4 alkyltri C1-4 alkoxysilanes such as 3-glycidyloxypropyltriethoxysilane, glycidyloxydi C2-4 alkyldi C1-4 alkoxysilanes such as 3-glycidyloxypropylmethyldimethoxysilane and 3-glycidyloxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyl (epoxycycloalkyl)C2-4 alkyltriC1-4 alkoxysilanes such as 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc.], alkoxysilanes having an amino group [aminoC2-4 alkyltriC1-4 alkoxysilanes such as 2-aminoethyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc., aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, etc., 2-[N-(2-aminoethyl)amino] (2-amino C2-4 alkyl)amino C2-4 alkyltri C1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, and 3-[N-(2-aminoethyl)amino]propyltriethoxysilane; (amino C2-4 alkyl)aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane and 3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane;Alkoxysilanes having a mercapto group (mercapto C2-4 alkyltri C1-4 alkoxysilanes such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc., mercaptodi C2-4 alkyldi C1-4 alkoxysilanes such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc.), alkoxysilanes having a vinyl group (vinyltri C1-4 alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.), ethylene Examples of the silane coupling agent include alkoxysilanes having a radically unsaturated bond group [(meth)acryloxyC2-4 alkyltriC1-4 alkoxysilanes such as 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, and 3-(meth)acryloxypropyltriethoxysilane, and (meth)acryloxydiC2-4 alkyldiC1-4 alkoxysilanes such as 3-(meth)acryloxypropylmethyldimethoxysilane and 3-(meth)acryloxypropylmethyldiethoxysilane, etc.]. These silane coupling agents can be used alone or in combination of two or more. Of these silane coupling agents, silane coupling agents having an amino group are preferred.

[0100] The silicon-based crosslinking agent is preferably added to the anchor coat layer F in an amount of 0.05 to 4.00% by mass, more preferably 0.10 to 3.50% by mass, and even more preferably 0.15 to 3.00% by mass. The addition of the silicon-based crosslinking agent promotes film hardening and improves cohesive strength, resulting in a film with excellent water-resistant adhesion and also expected to prevent oligomer exposure. If the amount added exceeds 4.00% by mass, the film hardens and improves cohesive strength, but some unreacted portions may be generated, potentially reducing interlayer adhesion. On the other hand, if the amount added is less than 0.05% by mass, sufficient cohesive strength may not be obtained.

[0101] The polyester resin used in the anchor coat layer F is produced by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The molecular weight of the polyester resin is not particularly limited as long as it can provide sufficient film toughness, coatability, and solvent solubility for use as a coating material, but the number average molecular weight is 1,000 to 50,000, more preferably 1,500 to 30,000. The functional group at the polyester end is also not particularly limited, and may be an alcohol end, a carboxylic acid end, or both. However, when an isocyanate-based curing agent is used in combination, it is preferable to use a polyester polyol that is predominantly alcohol-terminated.

[0102] The Tg of the polyester resin used in the anchor coat layer F is preferably 10°C or higher. If the temperature is lower than this, the resin will become tacky after the coating operation, making blocking more likely to occur and making the winding operation after coating more difficult. If the Tg is 10°C or lower, it will be difficult to prevent blocking even under conditions where the pressure near the winding core is high, even with the addition of an anti-blocking agent. The Tg temperature is more preferably 15°C or higher, and even more preferably 20°C or higher.

[0103] The polyester resin used in the anchor coat layer F is prepared by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The polycarboxylic acid component of the polyester resin can contain at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. Ortho-orientation improves solubility in solvents, enabling uniform coating on the substrate, i.e., the biaxially oriented polypropylene film according to an embodiment of the present invention. A uniformly coated film reduces variation in barrier performance, thereby contributing to the suppression of oligomer whitening. Furthermore, ortho-orientation results in a film with excellent flexibility and improved interfacial adhesion, thereby reducing damage to the substrate due to moist heat treatment and leading to the suppression of oligomer formation. Examples of aromatic polycarboxylic acids or anhydrides in which carboxylic acids are substituted at the ortho position include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracenecarboxylic acid or its anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimide group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, and a naphthyl group. Furthermore, polyester polyols having a content of these compounds of 70 to 100 mol % relative to 100 mol % of the total polycarboxylic acid components are particularly preferred because they have a high effect of improving barrier properties and excellent solvent solubility as a coating material.

[0104] The polyester resin used in the anchor coat layer F may be copolymerized with other polycarboxylic acid components. Specifically, examples of aliphatic polycarboxylic acids that can be used include succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid; examples of unsaturated bond-containing polycarboxylic acids include maleic anhydride, maleic acid, and fumaric acid; examples of alicyclic polycarboxylic acids include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; and examples of aromatic polycarboxylic acids include terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, diphenic acid and its anhydride, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, and anhydrides or ester-forming derivatives of these dicarboxylic acids; and examples of polybasic acids that can be used alone or in mixtures of two or more thereof include p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these dihydroxycarboxylic acids. Among these, succinic acid, 1,3-cyclopentanedicarboxylic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalic acid, and diphenic acid are preferred from the viewpoint of solubility in organic solvents and gas barrier properties.

[0105] The polyhydric alcohol component of the polyester resin used in the anchor coat layer F is not particularly limited as long as it can synthesize a polyester that exhibits gas barrier filling performance, but it is preferable for the polyhydric alcohol component to contain at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, and 1,3-bishydroxyethylbenzene. Among these, it is most preferable to use ethylene glycol as the main component, since it is presumed that the fewer the number of carbon atoms between oxygen atoms, the less flexible the molecular chain becomes and the more difficult oxygen permeates.

[0106] The polyester resin used in the anchor coat layer F may be copolymerized with other polyhydric alcohol components. Specific examples of diols include 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of trihydric or higher alcohols include glycerol, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl)isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythritol. Polyesters containing glycerol and tris(2-hydroxyethyl)isocyanurate in combination are particularly preferred, as they have a moderately high crosslinking density due to their branched structure, resulting in good solubility in organic solvents and excellent barrier function.

[0107] Examples of catalysts used in the reaction to obtain the polyester resin used in the anchor coat layer F include acid catalysts such as tin-based catalysts such as monobutyl tin oxide and dibutyl tin oxide, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, and zirconia-based catalysts such as tetrabutyl zirconate. It is preferable to use a combination of the above-mentioned titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, which have high activity in esterification reactions, with the above-mentioned zirconia catalyst. The amount of the catalyst used is 1 to 1000 ppm, more preferably 10 to 100 ppm, based on the total mass of the reaction raw materials used. If the amount is less than 1 ppm, it is difficult to obtain the catalytic effect, and if it exceeds 1000 ppm, problems such as inhibition of the urethanization reaction may occur when an isocyanate curing agent is used.

[0108] When a polyester resin is used as the main component of the coating agent constituting the anchor coat layer F, it is particularly preferable to use an isocyanate-based curing agent to form a urethane resin. In this case, the coating layer becomes crosslinked, which has the advantage of improving heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use in boiling and retort packaging. On the other hand, there are problems with the liquid not being reusable after mixing with the curing agent, and a curing (aging) process is required after coating. Advantages include, for example, the fact that as a simple overcoat varnish, there is no risk of thickening of the coating liquid, easy management of coating production, the ability to dilute and reuse the coating liquid, and the elimination of the curing process (so-called aging process). In this case, the polyester used can be terminated with a polyol, a polycarboxylic acid, or a mixture of these without any problems. On the other hand, the resin of the coating layer is linear, which may result in insufficient heat resistance or abrasion resistance, or problems with use in boiling and retort packaging.

[0109] When a curing agent is used in the coating layer, an isocyanate curing system is preferred from the standpoint of heat resistance of the film, since the coating is applied to the film. In this case, it is preferable that the resin component of the coating material is a polyester polyol. On the other hand, when an epoxy compound is used as the curing agent, a polyester polycarboxylic acid is preferred. In these cases, the coating layer becomes crosslinked, which has the advantage of improving heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use in boiled or retort packaging. On the other hand, there are problems with this: the liquid cannot be reused after mixing the curing agent, and a curing (aging) process is required after application.

[0110] When the polyester resin has hydroxyl groups, the polyisocyanate compound used in the coating agent reacts at least partially to form a urethane structure, thereby becoming highly polar as a resin component and causing aggregation between polymer chains, thereby further enhancing the gas barrier function. Furthermore, when the resin of the coating material is a linear resin, crosslinking with a trivalent or higher polyisocyanate can impart heat resistance and abrasion resistance. The polyisocyanate compound may be a diisocyanate, a trivalent or higher polyisocyanate, a low-molecular-weight compound, or a high-molecular-weight compound. It is preferable that the polyisocyanate compound contain an aromatic ring or an aliphatic ring in part of its skeleton from the viewpoint of improving the gas barrier function. Examples of isocyanates having an aromatic ring include toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; examples of isocyanates having an aliphatic ring include hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, or trimers of these isocyanate compounds; and compounds containing terminal isocyanate groups obtained by reacting an excess amount of these isocyanate compounds with low-molecular-weight active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, and triethanolamine, or high-molecular-weight active hydrogen compounds such as various polyester polyols, polyether polyols, and polyamides.

[0111] The method for forming the anchor coat layer F is not particularly limited, and conventionally known methods such as coating methods can be used. Among coating methods, preferred methods include offline coating and in-line coating. For example, in the case of an in-line coating method carried out in the process of producing the substrate, i.e., the biaxially oriented polypropylene film according to an embodiment of the present invention, the conditions for drying and heat treatment during coating will vary depending on the coating thickness and the conditions of the equipment, but it is preferable to send the film to a stretching step in the perpendicular direction immediately after coating and dry it in the preheating zone or stretching zone of the stretching step, and in such cases, it is usually preferable to use a temperature of about 50 to 250°C.

[0112] The method for applying the resin composition for the anchor coat layer F is not particularly limited as long as it is a method that can apply the resin composition to the surface of a film to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0113] When forming the anchor coat layer F, it is preferable to apply the resin composition for the anchor coat layer and then heat-dry it. The drying temperature is preferably 100 to 145°C, more preferably 110 to 140°C, and even more preferably 110 to 130°C. If the drying temperature is below 100°C, the anchor coat layer F may not be sufficiently dried. On the other hand, if the drying temperature exceeds 145°C, the film may be overheated, causing it to become brittle or shrink, resulting in poor processability. In particular, it is particularly preferable to first volatilize the solvent at a relatively low temperature of 80 to 110°C immediately after application, and then dry it at 120°C or higher, as this will result in a uniform film. In addition to drying, additional heat treatment at as low a temperature as possible is also more effective in promoting film formation of the anchor coat layer F.

[0114] [Protective Layer G on Inorganic Thin Film] The laminate according to an embodiment of the present invention may have a protective layer G on the inorganic thin film layer E, which is a gas barrier layer. The inorganic thin film layer made of a metal oxide layer is not a completely dense film, but has minute defects scattered therein. By forming the protective layer G by applying a specific protective layer resin composition described below to the metal oxide layer, the resin in the protective layer resin composition penetrates into the defect parts of the metal oxide layer, resulting in the effect of stabilizing the barrier properties of the gas barrier layer. In addition, by using a material with gas barrier properties for the protective layer G itself, the gas barrier performance of the laminate is also improved.

[0115] The amount of the protective layer G attached is 0.10 to 0.40 (g / m 2 ) is preferable. This allows the protective layer G to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. In addition, the cohesive force of the protective layer G itself is improved, and the adhesion between the inorganic thin film layer and the protective layer is also strengthened. The amount of the protective layer G attached is preferably 0.13 (g / m 2 ) or more, more preferably 0.16 (g / m 2 ) or more, more preferably 0.19 (g / m 2 ) or more, and preferably 0.37 (g / m 2 ) or less, more preferably 0.34 (g / m 2 ) or less, more preferably 0.31 (g / m 2 The amount of the protective layer G attached is 0.400 (g / m 2 ), the gas barrier properties are improved, but the cohesive force inside the protective layer G becomes insufficient and the uniformity of the protective layer G also decreases, which may cause unevenness or defects in the coat appearance and may prevent the gas barrier properties and adhesiveness from being fully exhibited. 2 If the thickness is less than 1 / 2 mm, sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0116] The resin composition used for the protective layer G formed on the surface of the inorganic thin film layer E may be a polyvinyl alcohol-based, urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resin, or the like, and may further contain an epoxy-based, isocyanate-based, melamine-based, silanol-based, or other curing agent.

[0117] The method for applying the resin composition for the protective layer is not particularly limited as long as it is a method that can apply the resin composition for the protective layer to the surface of a film to form a layer. For example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0118] When forming the protective layer G, it is preferable to apply the protective layer resin composition and then heat-dry it. The drying temperature is preferably 100 to 160°C, more preferably 110 to 150°C, and even more preferably 120 to 140°C. Drying temperatures below 100°C may result in insufficient drying of the protective layer G, or film formation of the protective layer G may not proceed, resulting in reduced cohesive strength and water-resistant adhesion, and consequently reduced barrier properties and hand-tearability. On the other hand, drying temperatures above 160°C may result in excessive heat being applied to the film, making it brittle and reducing puncture strength, or shrinking and reducing processability. It is particularly preferable to first volatilize the solvent from the protective layer resin composition at a relatively low temperature of 90 to 110°C immediately after application, and then dry it at 130°C or higher, since this produces a uniform and transparent film, i.e., the protective layer G. In addition to drying, additional heat treatment at as low a temperature as possible may be even more effective in promoting film formation of the protective layer G.

[0119] [Other Films] The packaging material according to the embodiment of the present invention includes the laminate according to the embodiment of the present invention and a film laminated on at least one of the two surfaces of the laminate according to the embodiment of the present invention. The film can impart certain functions to the packaging material according to the embodiment of the present invention. The film can be, for example, a film obtained by melt-extruding a plastic and, if necessary, stretching it in the longitudinal and / or transverse directions, cooling, and heat-setting it. Examples of plastics include polyamides such as nylon 4.6, nylon 6, nylon 6.6, and nylon 12, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, as well as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, wholly aromatic polyamide, polyamideimide, polyimide, polyetherimide, polysulfone, polystyrene, and polylactic acid. The film can be, for example, a heat-sealable film, a stretched polyolefin film, or a stretched polyester film.

[0120] The film can have any thickness depending on the desired purpose, such as mechanical strength and transparency. Although there are no particular limitations, a thickness of 5 to 250 μm is usually recommended, and when used as a packaging material, a thickness of 10 to 60 μm is desirable. However, it is necessary to consider the mono-material ratio of the packaging material, which will be described later.

[0121] The film may be a laminated film of one or more types of plastic films. When a laminated film is used, the type of laminate, the number of layers, the lamination method, etc. are not particularly limited, and can be arbitrarily selected from known methods depending on the purpose.

[0122] The packaging material according to an embodiment of the present invention may include a first film laminated on one side of the laminate according to an embodiment of the present invention and a second film laminated on the other side. For example, the packaging material according to an embodiment of the present invention may include a heat-sealable film (e.g., a heat-sealable polyolefin film) laminated on one side of the laminate according to an embodiment of the present invention and a stretched film laminated on the other side. Examples of stretched films include stretched polyolefin films and stretched polyester films.

[0123] [Adhesive Layer] The packaging material according to the embodiment of the present invention may further include an adhesive layer between the laminate according to the embodiment of the present invention and a film (e.g., a first film, a second film). For example, the adhesive layer may be sandwiched between the gas barrier layer of the laminate according to the embodiment of the present invention and a heat-sealable film, or between the biaxially oriented polypropylene film of the laminate according to the embodiment of the present invention and a stretched film. A general-purpose laminating adhesive can be used for the adhesive layer. For example, solvent-free, aqueous, or hot-melt adhesives containing poly(ester)urethane, polyester, polyamide, polyamine, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, casein, or the like as their main components can be used. Among these, adhesives obtained by crosslinking polyurethane, polyester, or polyamine resins are preferred from the viewpoints of heat resistance, flexibility capable of adapting to dimensional changes in each substrate, and improved gas barrier properties of the adhesive itself. However, caution is required, as there is a concern that if the film becomes too hard due to crosslinking, the barrier performance after bending may decrease. It is also effective to add inorganic substances such as particles to improve barrier performance. The adhesive layer can be applied by, for example, direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fountain coating, or other methods. To achieve sufficient adhesion, the thickness after drying is preferably 1 to 8 μm. It is more preferably 2 to 7 μm, and even more preferably 3 to 6 μm. If the coating weight is less than 1 μm, it becomes difficult to bond the entire surface, and the adhesive strength decreases. Furthermore, if the coating weight exceeds 8 μm, it takes a long time for the film to completely harden, unreacted material is likely to remain, and the adhesive strength decreases.

[0124] [Printed Layer] The packaging material according to the embodiment of the present invention may further include a printed layer. The printed layer may be, for example, between the laminate according to the embodiment of the present invention and a film (e.g., the first film or the second film), or may be laminated on the outside of at least one of them.

[0125] As the printing ink for forming the printed layer, aqueous and solvent-based resin-containing printing inks are preferably used. Among them, aqueous inks are particularly preferred from an environmental perspective. When using aqueous inks, it is preferable that the printed layer does not repellent (printability) and has sufficient adhesion to the film. The laminate according to the embodiment of the present invention can have excellent printability and adhesion with aqueous ink. When gravure printing is performed on the surface of a film using aqueous ink, the shape of the printed dots is observed, and the dot size and the degree of ink repellency are evaluated. A uniform dot size is preferred, and a uniform dot size and no repellency are more preferred. Examples of resins used in printing inks include acrylic resins, urethane resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, antifoaming agents, crosslinking agents, antiblocking agents, and antioxidants. The printing method for providing the printed layer is not particularly limited, and known printing methods such as offset printing, gravure printing, screen printing, etc. can be used. To dry the solvent after printing, known drying methods such as hot air drying, heat roll drying, and infrared drying can be used.

[0126] The laminate according to the embodiment of the invention can be suitably used to prepare packaging materials, and may also be used to prepare labels, for example.

[0127] The packaging material according to the embodiment of the present invention may be in the form of a film, for example.

[0128] [Examples of Use of Laminate] As described above, the laminate according to the embodiment of the present invention can be a laminate for a packaging material. The laminate according to the embodiment of the present invention is preferably used, for example, as a substrate when producing a packaging material including a substrate for a front printing layer / a heat-sealable film, or as a substrate when producing a packaging material including a substrate for a back printing layer / a gas barrier film / a heat-sealable film.

[0129] [Heat-sealable film] Examples of heat-sealable films include unstretched films, uniaxially stretched films, and biaxially stretched films made of low-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and polyester. In particular, heat-sealable polyolefin films such as unstretched films or uniaxially stretched films made of low-density polyethylene, linear low-density polyethylene, or polypropylene are preferred. From the viewpoint of ease of recycling, of low-density polyethylene, linear low-density polyethylene, and polypropylene, polypropylene is preferred.

[0130] [Properties of Laminate or Packaging Material] As described above, the laminate or packaging material according to the embodiment of the present invention can have any conceivable laminate structure for a packaging material. From the viewpoint of environmental impact, it is preferable to use fewer materials and fewer lamination processes. On the other hand, from the viewpoint of imparting functionality such as further improvement in barrier properties, printability, toughness, and stiffness, a structure including another film (e.g., a heat-sealable film, a stretched polyolefin film, or a stretched polyester film) is also one preferred structure. In this case, by laminating the printing layer on another film (e.g., a stretched polyolefin film or a stretched polyester film) on the front side, there is also the advantage that printing on the laminate according to the embodiment of the present invention is not necessary. Other suitable structures include laminating a white substrate film and the laminate according to the embodiment of the present invention to enhance concealment properties, or laminating an ultraviolet-blocking film and the laminate according to the embodiment of the present invention to provide light-blocking properties.

[0131] The laminate according to the embodiment of the present invention has an oxygen permeability of 100 ml / m under conditions of 23°C x 65% RH when bonded to another film via an adhesive to form a packaging material. ２ It is preferable that the viscosity is 90 ml / m or less in order to exhibit good gas barrier properties. ２ d MPa or less, more preferably 80 ml / m ２ ・d・MPa or less. Oxygen permeability is 100 ml / m ２If the viscosity exceeds d MPa, it becomes difficult to use the film in applications that require high gas barrier properties.

[0132] The laminate according to the embodiment of the present invention has a water vapor permeability of 3.0 g / m under conditions of 40°C x 90% RH when bonded to another film via an adhesive to form a packaging material. ２ It is preferable that the thickness is d or less in order to exhibit good gas barrier properties. More preferably, it is 2.5 g / m ２ d or less, more preferably 2.0 g / m ２ The water vapor permeability can be 3.0 g / m or less. ２ If d is exceeded, it becomes difficult to use the film in applications that require high gas barrier properties.

[0133] The laminate strength of the biaxially oriented polypropylene film is preferably 1.5 N / 15 mm or more, more preferably 2.0 N / 15 mm or more, even more preferably 2.5 N / 15 mm or more, even more preferably 2.7 N / 15 mm or more, and particularly preferably 2.8 N / 15 mm or more. There is no particular upper limit, but 10 N / 15 mm or less is sufficient. The laminate strength of the biaxially oriented polypropylene film can be measured by the method described in the Examples below (specifically, see the method for measuring the laminate strength using the first evaluation film).

[0134] The laminate strength of the laminate according to the embodiment of the present invention is 1.5 N / 15 mm or more, preferably 2.0 N / 15 mm or more, more preferably 2.5 N / 15 mm or more, even more preferably 2.7 N / 15 mm or more, and particularly preferably 2.8 N / 15 mm or more. There is no particular upper limit, but a strength of 10 N / 15 mm or less is sufficient. The laminate strength of the laminate according to the embodiment of the present invention is measured by the method described in the Examples below (specifically, see the method for measuring the laminate strength using the second evaluation film). When preparing the second evaluation film, an unstretched polypropylene film P1153-50 μm (CPP1) is laminated to the gas barrier layer or protective layer G (when the laminate according to the embodiment of the present invention includes the protective layer G) of the laminate according to the embodiment of the present invention.

[0135] The laminate according to an embodiment of the present invention is less likely to wrinkle in the sealed portion even when the heat-sealing temperature is high when processed into a packaging bag. When the sum of the heat shrinkage rate at 150°C in the longitudinal direction and the heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 25.0% or less, wrinkles and deformation in the sealed portion can be further reduced even when the temperature of the sealing bar is increased, thereby enabling faster bag production.

[0136] An example of a laminate configuration according to an embodiment of the present invention is a configuration in which the laminate of the present invention is used between a biaxially oriented polypropylene film provided with a printed layer and a heat-sealable film such as a non-oriented polypropylene film or a non-oriented linear low-density polyethylene film. Examples include (OPP or PET / printed layer) / adhesive layer / (aluminum or inorganic oxide vapor-deposited layer / OPP*) / adhesive layer / (CPP or LLDPE), (OPP or PET / printed layer) / adhesive layer / (gas barrier coating layer / OPP*) / adhesive layer / (CPP or LLDPE), etc. In the above layer configurations, " / " indicates the boundary between different components, and the abbreviations used are as follows: OPP*: biaxially oriented polypropylene film of the present application; OPP or PET: general biaxially oriented polypropylene film or biaxially oriented polyethylene terephthalate film.

[0137] The packaging material according to the embodiment of the present invention can be suitably used to produce a packaging bag. For example, when the packaging material according to the embodiment of the present invention has a heat-sealable film, a packaging bag can be produced by folding the packaging material according to the embodiment of the present invention and then thermally bonding the heat-sealable films of the packaging material according to the embodiment of the invention together. When the packaging material according to the embodiment of the present invention has a heat-sealable film, it is of course also possible to produce a packaging bag by thermally bonding the packaging material according to the embodiment of the present invention to another packaging material.

[0138] As described above, the packaging material made of the laminate of the present invention has excellent barrier properties and adhesive properties, and therefore can be used as various types of packaging, such as for general food, frozen food, vacuum packaging, boiled retort food, and microwave heating.

[0139] The shape of the packaging material made using the laminate of the present invention is not particularly limited and can take various shapes, such as a three-sided or four-sided pouch, a standing pouch, a spout pouch, etc.

[0140] The contents to be filled in the packaging bag using the packaging material of the present invention, i.e., the packaged item, are not particularly limited, and the contents may be liquid, powder, or gel. In addition, the contents may be food or non-food.

[0141] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0142] In the Examples section, the biaxially oriented polypropylene film after forming at least one of the coating layer D and the inorganic thin film layer E is referred to as a "laminate." The biaxially oriented polypropylene film after further forming a protective layer G is also referred to as a "laminate." In Examples 1 and 2 described below, the coating layer D was formed on the surface layer B of the biaxially oriented polypropylene film. In Examples 3, 6, and 7 and Comparative Examples 2 to 4 described below, the inorganic thin film layer E was formed on the surface layer B of the biaxially oriented polypropylene film. In Examples 8 to 13 and Comparative Example 5 described below, the anchor coat layer F was formed on the surface layer B of the biaxially oriented polypropylene film, and then the inorganic thin film layer E was formed on the anchor coat layer F. In Example 9, the protective layer G was formed on the inorganic thin film layer E.

[0143] In this example section, the surface layer B may be referred to as the "B layer." The surface layer C may be referred to as the "C layer."

[0144] (Measurement Methods) The physical properties of the raw materials used and the resulting films in the Examples and Comparative Examples were measured by the following methods. Note that in the following 1) to 4), the physical properties of the polypropylene resin used in each layer were measured, and in 5) to 16), the physical properties of the biaxially oriented polypropylene film were measured. In 17) to 18), the laminate was evaluated.

[0145] 1) Melting Point Using a PerkinElmer DSC8500 differential scanning calorimeter, 5 mg of a sample was packed into an aluminum pan and set therein, and melted at 230°C for 5 minutes under a nitrogen atmosphere. The sample was then cooled to 30°C at a scanning rate of -10°C / min, maintained at this temperature for 5 minutes, and then heated at a scanning rate of 10°C / min. The main peak temperature of the endothermic peak accompanying melting was taken as the melting point.

[0146] 2) Mesopentad fraction (mmmm) The mesopentad fraction is measured as follows: １３ The mesopentad fraction was calculated according to the method described in "Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973)". １３ C-NMR measurement was performed using an AVANCE 500 manufactured by BRUKER at 110°C by dissolving 200 mg of a sample in a mixed solution of o-dichlorobenzene and deuterated benzene in a ratio of 8:2 (volume ratio) at 135°C.

[0147] 3) Melt flow rate (MFR) Measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kgf.

[0148] 4) Number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) The molecular weight and molecular weight distribution of the polypropylene resin were determined using gel permeation chromatography (GPC) with monodisperse polystyrene as the standard. The measurement conditions for the column, solvent, etc. used in the GPC measurement are as follows: Solvent: 1,2,4-trichlorobenzene Column: TSKgel GMHHR-H(20)HT x 3 Flow rate: 1.0 ml / min Detector: RI Measurement temperature: 140°C

[0149] The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) are calculated from the molecular weight (M) at each elution position of the GPC curve obtained via the molecular weight calibration curve. ｉ ) number of molecules (N ｉ ) is defined by the following formula: Number average molecular weight: Mn = Σ(N ｉ ・M ｉ ) / ΣN ｉ Weight average molecular weight: Mw=Σ(N ｉ ・M ｉ２ ) / Σ(N ｉ ・M ｉ ) Molecular weight distribution: Mw / Mn When the baseline was unclear, the baseline was set in the range up to the lowest point of the high molecular weight base of the elution peak on the high molecular weight side closest to the elution peak of the standard substance.

[0150] 5) Thickness A cross section of a film solidified with a modified urethane resin was cut out with a microtome and observed with a differential interference microscope to measure the thickness of each layer.

[0151] 6) Haze The haze of the film was measured at 23° C. using a haze meter (300A manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 7105. The measurement was carried out twice, and the average value was calculated.

[0152] 7) Appearance A bromine light (VIDEO LIGHT VLG301 100V 300W, manufactured by LPL) was irradiated onto the film surface at an angle of approximately 45 degrees, and the appearance of the film was evaluated by visual observation according to the following criteria: A: No unevenness in appearance that would be problematic for the product was observed. B: Many unevenness in transparency due to stick-slip occurring on the longitudinal stretching rolls was observed. C: Very many unevenness in transparency due to stick-slip occurring on the longitudinal stretching rolls was observed, to a level that was not acceptable for use as a product.

[0153] 8) Tensile Modulus A sample measuring 10 mm in width and 180 mm in length was cut from the film using a razor. Measurements were performed in accordance with JIS K 7127. After leaving the film in an atmosphere of 23°C and 65% relative humidity for 12 hours, measurements were performed under conditions of 23°C, 65% relative humidity, a chuck distance of 100 mm, and a pulling speed of 200 mm / min. The average of five measurements was calculated and used as the longitudinal tensile modulus. The measuring device used was an Autograph AG5000A manufactured by Shimadzu Corporation. A sample measuring 180 mm in width and 10 mm in length was also cut from the film using a razor, and the widthwise tensile modulus was determined using the same method as for the longitudinal tensile modulus.

[0154] 9) Heat shrinkage was measured according to the following method in accordance with JIS Z 1712. The film was cut into pieces of 20 mm width and 200 mm length in both the longitudinal and transverse directions of the film, and then hung in a hot air oven at 150°C for 5 minutes. The length after heating was measured, and the ratio of the shrunk length to the original length was taken as the heat shrinkage.

[0155] 10) Wet Tension (mN / m) After aging the film at 23° C. and a relative humidity of 50% for 24 hours, the wet tension of the surface of the surface layer B and the surface layer C was measured in accordance with JIS K 6768 (1999).

[0156] 11) Surface Resistivity Value According to JIS K 6911 (1995), the film was aged at 23° C. and a relative humidity of 65% for 24 hours, and then the surface resistivity values ​​of the surface layer B and the surface layer C were measured.

[0157] 12) Three-dimensional average roughness SRa Using a contact-type three-dimensional surface roughness meter (manufactured by Kosaka Laboratory Co., Ltd.: Model ET-4000A), the average roughness SRa of surface layer B and surface layer C was measured by the stylus method under the following conditions: stylus tip radius: 0.5 μm, stylus pressure: 50 μN, cutoff value: 800 μm, measurement length: 500 μm, measurement speed: 0.1 μm / sec, measurement interval: 5 μm

[0158] 13) Drop-off Rate of Antiblocking Agent Using a universal tensile tester (STM-T-50BP manufactured by Toyo Baldwin Co., Ltd.), a 0.5 kg weight (contact surface: 63 mm x 63 mm) with a bettin fabric attached was placed over the measurement surface of the film, and a friction test was carried out under the following conditions: Temperature: 23°C Relative humidity: 50% Number of frictions: 5 consecutive times on the part to be evaluated Pulling speed: 200 mm / min After the above treatment, the film was observed at a magnification of 600x using a tabletop microscope ("TM3030Plus Miniscope" manufactured by Hitachi, Ltd.), and the number of all antiblocking agent particles observed and the number of marks where the antiblocking agent had fallen off the film were counted, and the drop-off rate of the antiblocking agent was calculated using the following formula. Antiblocking agent removal rate (%) = (number of traces of antiblocking agent removed) / (total number of observed antiblocking agents and number of traces of antiblocking agent removed from the film) x 100

[0159] 14) Dynamic friction coefficient Two films were prepared, and the surface layer B of one film was superimposed on the surface of the surface layer C of the other film. The coefficient of dynamic friction was measured in accordance with JIS K 7125 (1999) using a universal tensile tester STM-T-50BP (manufactured by Toyo Baldwin Co., Ltd.) in an atmosphere of 23°C and relative humidity of 50%.

[0160] 15) Wrinkles in film rolls The produced biaxially oriented polypropylene film was wound up using a slitter to a width of 600 mm and a roll length of 1,500 m to produce a film roll, and the wrinkles on the surface layer of the film roll were visually evaluated according to the following criteria, with a rating of A being acceptable. A+: No wrinkles. A: There were weak wrinkles, but the wrinkles disappeared when a tension of about 5 N / m was applied to the drawn-out film. B: There were weak wrinkles, but the wrinkles disappeared when a tension of about 20 N / m was applied to the drawn-out film. C: There were strong wrinkles, and the wrinkles did not disappear even when a tension of about 20 N / m was applied to the drawn-out film.

[0161] 16) Guide Roll Stain After a 500 m length of film was passed through a slitter (NS-SLITTER FN-105 manufactured by Nishimura Manufacturing Co., Ltd.), the stain on the guide roll was evaluated, and a rating of A was deemed acceptable. A: No stain on the guide roll. B: Slight stain on parts of the guide roll. C: Stain on the entire surface of the guide roll.

[0162] 17) Composition and thickness of inorganic thin film layer on substrate film The laminates (after forming the inorganic thin film layer) obtained in the examples and comparative examples were measured for thickness composition using a fluorescent X-ray analyzer (Rigaku Corporation, "Supermini 200") based on a previously prepared calibration curve. The excitation X-ray tube conditions were 50 kV and 4.0 mA.

[0163] 18) Adhesion amount of coating layer D, anchor coat layer F, and protective layer G on substrate film In each example and comparative example, at the stage where the predetermined coating layer D, anchor coat layer F, and protective layer G were laminated on the substrate film (specifically, biaxially oriented polypropylene film), a test piece of 100 mm x 100 mm was cut out, and the coating layer was wiped off with either water, ethanol, or acetone. The adhesion amount of each layer was calculated from the change in mass of the film before and after wiping.

[0164] 19) Preparation of Evaluation Films: A polyurethane adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) was applied to a biaxially oriented polypropylene film to a thickness of 3 μm after drying at 80°C. Then, a non-oriented polypropylene film P1153-50 μm (CPP1) was dry-laminated on a metal roll heated to 60°C as a heat-sealable resin. The film was then aged at 40°C for 2 days (48 hours) to obtain a first evaluation film. The first evaluation film had a biaxially oriented polypropylene film, an adhesive layer (specifically, an adhesive layer formed with a polyurethane adhesive), and a heat-sealable resin layer, which were arranged in this order in the thickness direction of the first evaluation film. The polyurethane adhesive was applied to the surface layer B of the biaxially oriented polypropylene film. The first evaluation film was used to measure the laminate strength and evaluate the appearance of the heat-sealed portion, as shown in Table 3. A polyurethane adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) was applied to the laminate to a thickness of 3 μm after drying at 80 ° C., and then unstretched polypropylene film P1153-50 μm (CPP1) was dry-laminated on a metal roll heated to 60 ° C. as a heat-sealable resin. The film was then aged at 40 ° C. for 2 days (48 hours) to obtain a second evaluation film. The second evaluation film had a laminate, an adhesive layer (specifically, an adhesive layer formed with a polyurethane adhesive), and a heat-sealable resin layer, which were arranged in this order in the thickness direction of the second evaluation film. The polyurethane adhesive was applied to the coating layer D, inorganic thin film layer E, or protective layer G of the laminate. For example, in Example 9, the polyurethane adhesive was applied to the protective layer G. The second evaluation film was used for measuring oxygen permeability, water vapor permeability, and laminate strength (specifically, the laminate strength shown in Table 4) in all examples and comparative examples except for Example 8B and Comparative Example 1 shown in Table 4, and for evaluating the appearance of the heat-sealed portion.On the other hand, for Example 8B, a polyurethane adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) was applied to OPP-A (polypropylene film P2171-20 μm manufactured by Toyobo Co., Ltd.) so that the thickness after drying treatment at 80 ° C was 3 μm, and the laminate was then dry-laminated on a metal roll heated to 60 ° C to form a take-up roll. The same adhesive was applied to this roll so that the thickness after drying treatment at 80 ° C was 3 μm, and then unstretched polypropylene film P1153-50 μm (CPP1) was dry-laminated on a metal roll heated to 60 ° C as a heat-sealable resin, and aged at 40 ° C for 2 days (48 hours) to obtain a third evaluation film (sometimes referred to as "evaluation packaging material" or "packaging material" in the Examples section). The third evaluation film had OPP-A, an adhesive layer (specifically, an adhesive layer formed of a polyurethane-based adhesive), a laminate, an adhesive layer (specifically, an adhesive layer formed of a polyurethane-based adhesive), and a heat-sealable resin layer, which were arranged in this order in the thickness direction of the third evaluation film. The adhesive layer between the laminate and the heat-sealable resin layer was sandwiched between the inorganic thin film layer E of the laminate and the heat-sealable resin layer.

[0165] 20) Evaluation method of oxygen permeability The oxygen permeability of the second evaluation film or the third evaluation film (i.e., packaging material) was measured in accordance with JIS-K7126 Method B using an oxygen permeability measuring device (OX-TRAN (registered trademark) 2 / 22 manufactured by MOCON Corporation) in an atmosphere of a temperature of 23°C and a humidity of 65% RH. The oxygen permeability was measured in the direction in which oxygen permeated from the base film side of the packaging material to the heat-sealable layer side.

[0166] 21) Evaluation method for water vapor permeability The water vapor permeability of the second evaluation film or the third evaluation film (i.e., packaging material) was measured in accordance with JIS-K7129 Method B using a water vapor permeability measuring device ("PERMATRAN-W 3 / 33MG" manufactured by MOCON) under an atmosphere of a temperature of 40°C and a humidity of 90% RH. The water vapor permeability was measured in the direction in which water vapor permeated from the base film side to the heat-sealable layer side.

[0167] 22) Laminate Strength A test piece measuring 15 mm wide and 200 mm long was cut from the second or third evaluation film (i.e., packaging material), and the laminate strength was measured using a Tensilon universal testing machine (Tensilon UMT-II-500, manufactured by Toyo Baldwin Co., Ltd.) at a temperature of 23°C and a relative humidity of 65% (see Table 4). To measure the laminate strength, the heat-sealable resin layer of the second or third evaluation film was gripped and a peel test was performed at a tensile speed of 200 mm / min and a peel angle of 90°. The laminate strength is the peel strength measured during this peel test. A peel test was performed under the same conditions except that a test piece measuring 15 mm wide and 200 mm long was cut from the first evaluation film, and the laminate strength was measured (see Table 3).

[0168] 23) Appearance Evaluation of Heat-Sealed Portions of Packaging Materials The heat-sealable films of the second evaluation film or the third evaluation film (i.e., packaging material) were heat-sealed together using a heat sealer to form a three-sided sealed bag measuring 130 mm x 180 mm. This resulted in a three-sided sealed bag. The seal bar width was 10 mm and the heat-sealing temperature was 150°C at a pressure of 0.2 MPa for 1 second. The three-sided sealed bag was visually evaluated for the appearance of wrinkles in the heat-sealed portions (see Table 4). A: No wrinkles were observed in the heat-sealed portions in either the width or length direction of the film. B: Wrinkles were observed in the heat-sealed portions in only one of the width or length directions of the film. C: Wrinkles were observed in the heat-sealed portions in both the width and length directions of the film. Three-sided sealed bags were produced under the same conditions except for using the first evaluation film, and the appearance of wrinkles in the heat-sealed portions was visually evaluated (see Table 3).

[0169] The various biaxially oriented polypropylene films, laminates, etc. used in the present examples and comparative examples are described below.

[0170] [Film Raw Material Resin] Details of polypropylene resins PP-1 to PP-6, which were raw materials used in the Examples and Comparative Examples, are shown in Table 1. The antiblocking agent masterbatch (hereinafter referred to as MB-1) used PP-3 shown in Table 1 as the polypropylene resin, and porous silica particles with an average particle size of 2.9 μm and a pore volume of 1.6 mL / g as the antiblocking agent (AB agent), and the content of the antiblocking agent in MB-1 was 5.0 mass%.

[0171]

[0172] (OPP1 to OPP12) A method for producing biaxially oriented polypropylene films OPP1 to OPP12 will be described.

[0173] (Biaxially oriented polypropylene film (OPP1)) For the base layer A, a blend of 70% by mass of PP-1 and 30% by mass of PP-2 was used. For the surface layer B and surface layer C, a blend of 26% by mass of PP-3, 20% by mass of PP-4, 50% by mass of PP-5, and 4% by mass of MB-1 was used. For the base layer A, a 45 mm extruder was used, for the surface layer B, a 25 mm extruder was used, and for the surface layer C, a 20 mm extruder was used. The raw material resins were melted at 250°C and co-extruded from a T-die into a sheet, and the sheet was cooled and solidified so that the surface layer B came into contact with a cooling roll at 30°C, and then stretched 4.5 times in the longitudinal direction (MD) at 135°C. Next, in a tenter, both ends of the film in the width direction were clamped with clips, preheated to 173 ° C., stretched 8.2 times in the width direction (TD) at 164 ° C., and then heat-set at 171 ° C. while relaxing 6.7% in the width direction (TD) to obtain a biaxially oriented polypropylene film with a three-layer structure of surface layer B / base layer A / surface layer C. The surfaces of surface layer B and surface layer C of the biaxially oriented polypropylene film were subjected to corona treatment using a corona treater manufactured by Softal Corona & Plasma GmbH at an applied current value of 0.75 A, and then wound up on a winder to obtain a biaxially oriented polypropylene film. The total thickness of the obtained biaxially oriented polypropylene film was 20 μm (thicknesses of surface layer B / base layer A / surface layer C were 1.3 μm / 17.4 μm / 1.3 μm).

[0174] (Biaxially oriented polypropylene films (OPP2 to 5)) Biaxially oriented polypropylene films OPP2 to 5 were obtained in the same manner as OPP1, except that the raw material compositions and film-forming conditions for surface layer B and surface layer C were as shown in Table 2.

[0175] (Biaxially oriented polypropylene films (OPP6, 7, 10, 11)) Biaxially oriented polypropylene films were obtained under the same conditions as for OPP1, except that the raw material compositions of surface layer B and surface layer C were changed as shown in Table 2.

[0176] (Biaxially oriented polypropylene film (OPP8)) An attempt was made to obtain a biaxially oriented polypropylene film under the same conditions as OPP1, except that in the raw material composition of surface layer B and surface layer C, PP-6, with a melting point of 125° C. was used instead of PP-5, with a melting point of 140° C. However, during longitudinal stretching, the film stuck to the stretching rolls, causing the stretching initiation point to become unstable, and uniform stretching was not possible, making it impossible to stably obtain a biaxially oriented polypropylene film with uniform properties.

[0177] (Biaxially oriented polypropylene film (OPP9)) The raw material composition was the same as that of OPP8, and the film production conditions were almost the same as those of OPP8, except that the longitudinal stretching temperature was lowered by 10°C to 125°C, the width direction stretching preheating temperature was 167°C, and the heat setting temperature was changed to 169°C (see Table 2 for details).

[0178] (Biaxially oriented polypropylene film (OPP12)) A biaxially oriented polypropylene film was obtained under almost the same conditions as OPP1, except that the raw material composition of the base layer A was changed as shown in Table 2 and only PP-4, a polypropylene-based resin with a melting point of 159°C, was used as the raw material of the base layer A.

[0179] The raw material composition of each layer of each film (OPP1 to 12), the thickness of each layer, and the film production conditions are shown in Table 2, and various physical properties and evaluations are shown in Table 3.

[0180]

[0181]

[0182]

[0183] The biaxially oriented polypropylene films obtained in OPP1 to 5 had few wrinkles in the obtained film rolls, and the films cut from the film rolls had good lamination strength, so they also had good adhesive properties.

[0184] In contrast, the OPP6 film had a low content of PP-5 in the surface layer B, and therefore when an unstretched polypropylene film was laminated on the surface layer B, the lamination strength with the unstretched polypropylene film was poor.

[0185] The OPP7 film had poor film formability due to unstable longitudinal stretching caused by a high PP-5 content in surface layers B and C. Stretching unevenness occurred on the longitudinal stretching rolls, resulting in poor appearance of the biaxially oriented polypropylene film.

[0186] The film of OPP8 did not contain PP-5 in the surface layers B and C, and therefore the longitudinal stretching was even more unstable than that of OPP7, resulting in poorer film formability. Not only could a biaxially oriented polypropylene film not be stably obtained, but also a great deal of stretching unevenness occurred on the longitudinal stretching rolls, resulting in a very poor appearance of the film.

[0187] In OPP9, the film-forming conditions of OPP8 were changed to lower the longitudinal stretching temperature, widthwise stretching preheating temperature, and heat setting temperature, thereby enabling stable production of biaxially oriented polypropylene film. However, the antiblocking agent loss rate was high and there was considerable guide roll contamination. Furthermore, because surface layer B did not contain PP-5, the adhesion on surface layer B was poor.

[0188] OPP10 had poor adhesion because it did not contain PP-5 in the surface layer B. Furthermore, when an unstretched polypropylene film was further laminated on the surface layer B, the lamination strength with the unstretched polypropylene film was poor.

[0189] In OPP11, since the surface layer B did not contain PP-5, the laminate strength was low.

[0190] The OPP12 film had a high heat shrinkage rate in both the longitudinal and transverse directions at 150°C because the raw material for the base layer A was PP-4, i.e., a polypropylene resin with a melting point of 159°C. As a result, many wrinkles occurred in the heat-sealed area of ​​the laminated laminate, which resulted in a poor appearance and made it unusable as a packaging bag.

[0191] The preparation of the laminate will be described below.

[0192] (Coating Layer D) Details of the coating liquid for forming the coating layer D used in the present examples and comparative examples are described below. The coating liquids used in Examples 1 and 2 are shown in Table 4. In Example 1, coating layer 1 was formed as the coating layer D. In Example 2, coating layer 2 was formed as the coating layer D.

[0193] [Polyvinyl alcohol resin (a)] To 90 parts by mass of purified water, 10 parts by mass of a fully saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: G Polymer OKS8049Q (saponification degree 99.0% or more, average polymerization degree 450) was added, and the mixture was heated to 80°C with stirring, and then stirred for about 1 hour. The mixture was then cooled to room temperature, thereby obtaining a nearly transparent polyvinyl alcohol solution (PVA solution) with a solids content of 10%.

[0194] [Inorganic layered compound dispersion (b)] 5 parts by mass of montmorillonite (trade name: Kunipia F, manufactured by Kunimine Industries Co., Ltd.), an inorganic layered compound, was added to 95 parts by mass of purified water with stirring, and the mixture was thoroughly dispersed using a homogenizer at a setting of 1500 rpm. Thereafter, the mixture was kept at 23°C for 1 day to obtain an inorganic layered compound dispersion with a solid content of 5%.

[0195] [Coating Liquid 1 Used for Coating Layer 1] A coating liquid (resin composition for coating layer) was prepared by mixing the materials in the following blending ratio: Ion-exchanged water 15.00% by mass, Isopropyl alcohol 15.00% by mass, Polyvinyl alcohol resin (a) 30.00% by mass, Inorganic layer compound dispersion (b) 40.00% by mass.

[0196] [Coating of Coating Solution 1 on a Film (Lamination of Coating Layer 1)] The coating solution prepared above was applied to the corona-treated surface of a substrate film (specifically, a biaxially oriented polypropylene film) by gravure roll coating, pre-dried at 90°C for 4 seconds, and then fully dried at 120°C for 4 seconds to obtain a coating layer. The coating layer adhesion amount at this time was 0.30 g / m ２ Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminate provided with the coating layer 1 was produced.

[0197] [Preparation of Coating Solution 2 Used for Coating Layer 2] A solution obtained by hydrolyzing tetraethoxysilane with 0.02 mol / L hydrochloric acid was added to a 5 wt % aqueous solution of polyvinyl alcohol resin (PVA) having a saponification degree of 99% and a polymerization degree of 2400, and the solution was diluted with SiO ２ The mixture was mixed in a ratio of 40 / 60 to obtain coating liquid 2.

[0198] [Coating of Coating Liquid 2 on Film (Lamination of Coating Layer 2)] The coating liquid prepared above was applied to the corona-treated surface of a substrate film (specifically, a biaxially oriented polypropylene film) by gravure roll coating, pre-dried at 90°C for 4 seconds, and then fully dried at 120°C for 4 seconds to obtain a coating layer. The coating layer adhesion amount at this time was 1.00 g / m ２ Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminate provided with the coating layer 2 was produced.

[0199] (Inorganic thin film layer E) The method for producing the inorganic thin film layer E used in each example and comparative example is described below. The inorganic thin film layer E used in examples 3 and 6 to 13 and comparative examples 2 to 5 is shown in Table 4. In example 3, inorganic thin film layer E-1 was formed as the inorganic thin film layer E. In example 6, inorganic thin film layer E-2 was formed as the inorganic thin film layer E. In examples 7 to 13 and comparative examples 2 to 5, inorganic thin film layer E-3 was formed as the inorganic thin film layer E.

[0200] (Formation of Inorganic Thin Film Layer E-1 (Vapor Deposition 1)) For the inorganic thin film layer E-1, metal aluminum was vapor-deposited on a substrate film (specifically, a biaxially oriented polypropylene film) or on the anchor coat layer of a biaxially oriented polypropylene film with an anchor coat layer. Using a small vacuum vapor deposition device (VWR-400 / ERH, manufactured by ULVAC KIKO Co., Ltd.), －３ After reducing the pressure to below Pa, aluminum foil with a purity of 99.9% was placed in a Nilaco evaporation source CF-305W from below the substrate (i.e., biaxially oriented polypropylene film or biaxially oriented polypropylene film with an anchor coat layer), and metallic aluminum was heated and evaporated to form a metallic aluminum film with a thickness of 70 nm.

[0201] (Formation of Inorganic Thin Film Layer E-2 (Vapor Deposition 2)) For the inorganic thin film layer E-2, silicon oxide was vapor-deposited on a substrate film (specifically, a biaxially oriented polypropylene film) or on the anchor coat layer of a biaxially oriented polypropylene film with an anchor coat layer. Using a small vacuum vapor deposition device (VWR-400 / ERH, manufactured by ULVAC KIKO Co., Ltd.), －３ After reducing the pressure to below 1 Pa, silicon dioxide was placed in a Nilaco evaporation source B-110 from below the substrate and evaporated by heating to form a silicon dioxide film with a thickness of 40 nm.

[0202] (Formation of Inorganic Thin Film Layer E-3 (Vapor Deposition 3)) As the inorganic thin film layer E-3, a composite oxide layer of silicon dioxide and aluminum oxide was formed by electron beam vapor deposition on a substrate film (specifically, a biaxially oriented polypropylene film) or on the anchor coat layer of a biaxially oriented polypropylene film with an anchor coat layer. The vapor deposition source was a granular SiO 2 layer of about 3 mm to 5 mm. ２ (purity 99.9%) and Al ２ O ３ (purity 99.9%) was used. The inorganic thin film layer (SiO ２ / Al ２ O ３ The thickness of the composite oxide layer was 20 nm. The composition of the composite oxide layer was SiO ２ / Al ２ O ３ The mass ratio was 70 / 30.

[0203] (Anchor Coat Layer F) Below, a method for producing the anchor coat layer F is described. In Examples 8 to 13 and Comparative Example 5, an anchor coat layer F-1 was formed as the anchor coat layer F. [Polyester Resin (a)] A polyester polyol (DF-COAT GEC-004C manufactured by DIC Corporation: solid content 30%) was used as the polyester component.

[0204] [Polyisocyanate Crosslinking Agent (b)] As the polyisocyanate component, a trimethylolpropane adduct of metaxylylene diisocyanate ("Takenate D-110N" manufactured by Mitsui Chemicals, Inc.: solid content 75%) was used.

[0205] [Silane Coupling Agent (c)] As the silane coupling agent, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane ("KBM-603" manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

[0206] [Coating Liquid 1 for Anchor Coat Layer F-1] A solution (15% by mass) of silane coupling agent (c) dissolved in acetone and polyisocyanate crosslinking agent (b) were mixed in the following ratio and stirred for 10 minutes using a magnetic stirrer. The obtained mixture was diluted with methyl ethyl ketone and 1-methoxy-2-propanol (hereinafter referred to as PGM), and polyester resin (a) was then added to obtain the target coating liquid 1. The mixing ratio is shown below: Polyester resin (a) 10.62% by mass Polyisocyanate crosslinking agent (b) 4.07% by mass Silane coupling agent (c) *acetone diluted solution 1.73% by mass Methyl ethyl ketone 69.55% by mass PGM 14.03% by mass

[0207] (Coating of coating liquid onto film (lamination of anchor coat layer)) Coating liquid 1 was applied onto the corona-treated surface of a substrate film (specifically, a biaxially oriented polypropylene film) by gravure roll coating, pre-dried at 95°C for 4 seconds, and then fully dried at 115°C for 4 seconds to obtain an anchor coat layer. The adhesion amount of the anchor coat layer at this time was 0.40 g / m２ Thereafter, a post-heat treatment was carried out at 40°C for 4 days (96 hours) to obtain a biaxially oriented polypropylene film with an anchor coat layer.

[0208] (Protective Layer G) The method for producing the protective layer G used in Example 9 is described below. In Example 9, protective layer 1 was formed as the protective layer G. [Coating Solution 1 Used for Protective Layer G] A solution obtained by hydrolyzing tetraethoxysilane with 0.02 mol / L hydrochloric acid was added to a 5 wt % aqueous solution of polyvinyl alcohol resin (PVA) having a saponification degree of 99% and a polymerization degree of 2400, and SiO ２ The mixture was mixed in a ratio of 60 / 40 to obtain a gas barrier protective layer solution (Coating Solution 1). (Coating of Coating Solution onto Film (Laminating of Protective Layer)) The aforementioned Coating Solution 1 was applied onto the inorganic thin film layer of the laminate by gravure roll coating, and dried in a dry oven at 120°C for 10 seconds to obtain Protective Layer 1. The coating amount of Protective Layer 1 at this time was 0.30 g / m ２ Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminate provided with a protective layer 1 was produced.

[0209] In this manner, a laminate was produced.

[0210] The laminate was used to prepare a second evaluation film (see all Examples except Example 8B, and Comparative Examples 2 to 5) or a third evaluation film (see Example 8B), and the oxygen permeability, water vapor permeability, and laminate strength were measured, and the appearance of the heat-sealed portion was evaluated. In Comparative Example 1, the first evaluation film was prepared using OPP1 instead of the laminate, and the oxygen permeability, water vapor permeability, and laminate strength were measured, and the appearance of the heat-sealed portion was evaluated. The results are shown in Table 4.

[0211] In this table, AC layer F represents anchor coat layer F. Inorganic layer E represents inorganic thin film layer E. OTR represents oxygen transmission rate. WVTR represents water vapor transmission rate.

[0212] INDUSTRIAL APPLICABILITY The present invention is industrially applicable since it relates to a laminate, a packaging material, a packaging bag, and a packaging body.

Claims

1. A laminate comprising a biaxially oriented polypropylene film including a base layer A made of a polypropylene-based resin composition, a surface layer B made of a polypropylene-based resin composition, and a surface layer C made of a polypropylene-based resin composition, and a gas barrier layer provided on surface layer B or surface layer C, and satisfying the following (1) to (4): (1) The heat shrinkage rate at 150°C in the longitudinal direction of the biaxially oriented polypropylene film is 0.0% or more and 10.0% or less. (2) The heat shrinkage rate at 150°C in the width direction of the biaxially oriented polypropylene film is 0.0% or more and 15.0% or less. (3) Both surface layer B and surface layer C contain an antiblocking agent, and the dropout rate of the antiblocking agent in both surface layer B and surface layer C is 10% or less. (4) The laminate strength of the laminate is 1.5 N / 15 mm or more.

2. The laminate according to claim 1, wherein the surface of said surface layer B and / or said surface layer C has a surface wetting tension of 36 mN / m or more.

3. A laminate according to claim 1 or 2, wherein the surface layer B and the surface layer C contain 25% by mass or more and 85% by mass or less of a polypropylene-based resin having a melting point of 130°C or more and 158°C or less.

4. A laminate described in claim 1 or 2, wherein the polypropylene resin composition of the base layer A contains 70% by mass or more of a polypropylene resin having a mesopentad fraction ([mmmm]%) of 95.0% or more and 99.9% or less and a melting point of 160°C or more and 175°C or less.

5. The laminate according to claim 1 or 2, wherein the surface resistivity of the surface layer B and / or the surface layer C is 14.0 Log Ω or more.

6. The laminate according to claim 1 or 2, wherein the gas barrier layer is an inorganic thin film layer containing aluminum, aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide.

7. The laminate according to claim 1 or 2, wherein the gas barrier layer is a coating layer containing at least one of polyvinyl alcohol resin, polyester resin, polyurethane resin, and inorganic layered compound.

8. The laminate according to claim 1 or 2, further comprising an anchor coat layer between the biaxially oriented polypropylene film and the gas barrier layer.

9. The laminate according to claim 1 or 2, further comprising a protective layer laminated on the gas barrier layer.

10. The laminate according to claim 1 or 2, which is used for heating in a microwave oven.

11. A packaging material comprising the laminate according to claim 1 or 2 and a film laminated to the laminate.

12. The packaging material according to claim 11, wherein the film laminated to the laminate is a heat-sealable polyolefin film.

13. The packaging material according to claim 12, wherein the laminate has a first surface on which the heat-sealable polyolefin film is laminated, and a second surface opposite to the first surface, and further comprises a stretched polyolefin film or stretched polyester film laminated to the second surface of the laminate.

14. The packaging material of claim 11, further comprising an adhesive layer laminated onto the gas barrier layer.

15. A packaging bag made using the packaging material according to claim 11.

16. A package comprising the packaging bag according to claim 15 and an item packaged in the packaging bag.

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