Laminate using biaxially oriented polypropylene film, packaging material, and package

Abstract

Provided is a laminate comprising: a biaxially oriented polypropylene film having a surface layer B comprising a polypropylene-based resin composition on one surface of a base material layer A comprising a polypropylene-based resin composition; and a gas barrier layer provided on the surface layer B, the laminate satisfying the following (1) to (5).　(1) The Martens hardness of the surface layer B is 248 N / mm2 or less.　(2) The wetting tension of the surface layer B is 36 mN / m or greater.　(3) The sum of the thermal shrinkage rate in the longitudinal direction of the biaxially oriented polypropylene film at 150ºC and the thermal shrinkage rate in the width direction thereof at 150ºC is 0.0-25.0%.　(4) The surface layer B contains an anti-blocking agent, and the anti-blocking agent has a fall-off rate of 10% or less.　(5) The three-dimensional average roughness SRa of the surface layer B is 10 nm or greater.

Description

Laminate, packaging material, and package using biaxially oriented polypropylene film

[0001] The present invention relates to a laminate, a packaging material, and a package 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] In food packaging, films are required to have gas barrier properties. Because biaxially oriented polypropylene films have inferior oxygen barrier properties compared to nylon films and polyester films, they are sometimes used as laminates with a gas barrier layer. Furthermore, food packaging bags are used with a printed layer to enhance content display and design. That is, laminate films used for food packaging include a film laminated with a printed film and 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 printing substrate layer / printing layer / adhesive layer / inorganic thin film layer / substrate layer for vapor deposition / adhesive layer / sealant film, in which each substrate layer and sealant film are made of the same polypropylene material from the viewpoint of recycling, can be cited (Patent Document 1).

[0004] In general, biaxially oriented polypropylene films can have poor slip properties or can suffer from blocking, where films stick to each other, making them difficult to work with when processed, so it is known that anti-blocking agents are added.

[0005] When printing on biaxially oriented polypropylene film, improvements in the transferability of the printing ink from the printing roll to the film surface and the adhesion of the printing ink to the film surface are required from the standpoints of print color development and color fading. Furthermore, when laminating a gas barrier layer onto biaxially oriented polypropylene film, improved adhesion between the film and the barrier layer is required to ensure uniform lamination and improve processability. However, because polypropylene resins are nonpolar and have low surface energy, biaxially oriented polypropylene film may not exhibit sufficient adhesion to vapor-deposited layers, coating layers, printing inks, etc.

[0006] As a film with improved adhesion to printing ink, for example, Patent Document 2 discloses that an antiblocking agent is blended into the film to form a surface layer with a predetermined surface roughness and wetting tension.

[0007] Furthermore, when an aluminum vapor-deposited film having gas barrier properties is provided on a surface layer, a film that has excellent adhesion to the aluminum vapor-deposited film is disclosed in, for example, Patent Document 3, which discloses a film containing an antiblocking agent to form a surface layer having a relatively small surface roughness and a predetermined wetting tension.

[0008] International Publication No. WO2021 / 020400 International Publication No. 2018 / 142983 International Publication No. 2022 / 004340

[0009] However, the film described in Patent Document 2 had poor adhesion to an aluminum vapor-deposited film when the aluminum vapor-deposited film was provided on the surface layer. Also, 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.

[0010] The present invention aims to provide a laminate that is excellent in workability when a biaxially oriented polypropylene film having excellent thermal dimensional stability and mechanical strength and an excellent appearance is used and a gas barrier layer such as a vapor deposition layer or a coating layer is provided on the film, and that also has excellent adhesion to the gas barrier layer.

[0011] As a result of extensive research into achieving this object, the present invention has been able to solve the above-mentioned problems by controlling the composition of the polypropylene resin composition of surface layer B and film-forming conditions when forming a laminate in which a gas barrier layer is laminated using a biaxially oriented polypropylene film having a base layer A made of a polypropylene resin composition and a surface layer B made of a polypropylene resin composition on one side of the base layer A. That is, the present invention has the following configuration.

[0012] 1. A laminate comprising a biaxially oriented polypropylene film having a surface layer B made of a polypropylene resin composition on one side of a base layer A made of a polypropylene resin composition, and a gas barrier layer provided on the surface layer B, wherein the laminate satisfies the following (1) to (5): (1) The Martens hardness of the surface layer B is 248 N / mm ２or less. (2) The wetting tension of the surface layer B is 36 mN / m or more. (3) 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. (4) The surface layer B contains an antiblocking agent, and the rate of dropout of the antiblocking agent is 10% or less. (5) The three-dimensional average roughness SRa of the surface layer B is 10 nm or more. 2. The laminate according to 1., wherein the surface layer B has a surface resistance of 14.0 Log Ω or more. 3. The laminate according to 1. or 2., wherein the surface layer B contains 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 biaxially oriented polypropylene film has a surface layer C on the other side of the base layer A, and the surface layer C is made of a polypropylene-based resin composition containing an antiblocking agent. 5. The laminate according to any one of 4., 5. The laminate according to 4., wherein the three-dimensional average roughness SRa of the surface layer C is 15 nm or more, and the rate of dropout of the antiblocking agent in the surface layer C is 10% or less. 6. The laminate according to 4. or 5., wherein the surface layer C has a wetting tension of 36 mN / m or more. 7. The laminate according to any one of 1. to 6., wherein the gas barrier layer is an inorganic thin film layer comprising one selected from the group consisting of aluminum, aluminum oxide, silicon oxide, and a composite oxide of silicon oxide and aluminum oxide. 8. The laminate according to any one of 1. to 7., wherein the gas barrier layer is a coating layer comprising one or more selected from the group consisting of polyvinyl alcohol resin, polyester resin, polyurethane resin, and inorganic layered compound. 9. The laminate according to any one of 1. to 8., wherein an anchor coat layer is laminated between the biaxially oriented polypropylene film and the gas barrier layer. 10. The laminate according to any one of 1. to 9., wherein a protective layer is laminated on the gas barrier layer. 11. A laminate according to any one of 1. to 10., characterized in that it is used for microwave heating. 12. A packaging material comprising the laminate according to any one of 1. to 11. 13. The packaging material according to 12., wherein a heat-sealable polyolefin film is laminated on the outermost surface side of the packaging material.14. The packaging material according to 13. above, wherein a stretched polyolefin film or a stretched polyester film is laminated on the opposite side of the heat-sealable polyolefin film of the laminate. 15. The packaging material according to any of 12. to 14. above, wherein a barrier adhesive layer is laminated on the gas barrier layer. 16. A packaging bag constructed using the packaging material according to any of 12. to 15. above. 17. A package formed by packaging an item using the packaging material according to any of 12. to 15. above, or the packaging bag according to 16. above.

[0013] According to the present invention, a laminate having excellent thermal dimensional stability and mechanical strength can be obtained. Furthermore, the workability when providing a gas barrier layer such as a vapor deposition layer or a coating layer on the film is excellent, and a laminate having excellent adhesion to the gas barrier layer can be stably obtained. As a result, the present invention can provide a laminate having high gas barrier properties.

[0014] The biaxially oriented polypropylene film used in the laminate of the present invention has a base layer A made of a polypropylene-based resin composition and a surface layer B made of a polypropylene-based resin composition. The biaxially oriented polypropylene film of the present invention preferably further has a surface layer C, and specifically, it is preferable that the surface layer B is on one side of the base layer A and the surface layer C is on the other side of the base layer A.

[0015] The biaxially oriented polypropylene film used in the laminate of the present invention satisfies the following (1) to (5). Hereinafter, the "biaxially oriented polypropylene film of the present invention" may be simply referred to as the "film." (1) The Martens hardness of the surface layer B is 248 N / mm ２ (2) The wetting tension of the surface layer B is 36 mN / m or more. (3) 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. (4) The surface layer B contains an antiblocking agent, and the rate of dropout of the antiblocking agent is 10% or less. (5) The three-dimensional average roughness SRa of the surface layer B is 10 nm or more.

[0016] (1) Substrate Layer A The substrate layer A preferably enhances the thermal dimensional stability, mechanical strength, and transparency of the biaxially oriented polypropylene film of the present invention. The substrate layer A is made of a polypropylene resin composition containing a polypropylene homopolymer as a main component. In the present invention, the term "main component" means that 70% by mass or more of the entire substrate layer A is polypropylene homopolymer, more preferably 80% by mass or more of the entire substrate layer A is polypropylene homopolymer, even more preferably 90% by mass or more of the entire substrate layer A is polypropylene homopolymer, and particularly preferably 95% by mass or more of the entire substrate layer A is polypropylene homopolymer.

[0017] (Polypropylene Homopolymer) The polypropylene homopolymer used in the base layer A 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.

[0018] Various suitable physical properties of the polypropylene homopolymer are described below, but when two or more different polypropylene homopolymers are used, it is preferable that the mass average values ​​of the physical properties of each polypropylene homopolymer fall within the numerical ranges described below.

[0019] The polypropylene homopolymer 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 susceptible to breakage 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 1-10 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 again at a scanning rate of 10°C / min. This was the main endothermic peak temperature observed during melting.

[0020] The polypropylene homopolymer 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%. A mesopentad fraction of 95.0% or higher enhances the crystallinity of the polypropylene resin, improving the melting point, crystallinity, and crystalline orientation of the crystals in the base layer A, thereby enhancing thermal dimensional stability and mechanical strength. A mesopentad fraction of 99.9% or lower facilitates reduction in the cost of polypropylene production and reduces breakage during film formation. The mesopentad fraction is measured by nuclear magnetic resonance (NMR).

[0021] The melt flow rate (MFR) of the polypropylene homopolymer used in the base layer A, as measured in accordance with JIS K 7210 (1995) Condition M (230°C, 2.16 kgf), is preferably 2.0 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 2.0 g / 10 min or higher, 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, making 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 lower, it is easy to maintain the film formability.

[0022] The polypropylene homopolymer 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.

[0023] The number average molecular weight (Mn) of the polypropylene homopolymer 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.

[0024] The polypropylene homopolymer 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 ratio of the polypropylene homopolymer 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 homopolymer 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, polymerizing a blend of catalysts with different performances, or using a catalyst that can achieve the desired molecular weight distribution.

[0025] (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 polypropylene resin using a Henschel mixer, master pellets prepared in advance using a melt kneader may be diluted with polypropylene 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.

[0026] (2) Surface Layer B When a gas barrier layer such as a vapor deposition layer or a coating layer is provided on the surface layer B, the surface layer B preferably has high adhesion to the gas barrier layer, and also preferably has slip properties and anti-blocking properties. The gas barrier layer is a layer having at least one of water vapor barrier properties, oxygen barrier properties, etc., and examples thereof include a vapor deposition layer and a coating layer. The surface layer B preferably contains 25% by mass to 85% by mass of a polypropylene-based resin having a melting point of 130°C to 158°C. That is, the polypropylene-based resin composition constituting the surface layer B preferably contains 25% by mass to 85% by mass of a polypropylene-based resin having a melting point of 130°C to 158°C. The surface layer B preferably contains a polypropylene-based resin having a melting point of 159°C to 175°C. On the other hand, in the surface layer B, it is preferable that the polypropylene-based resin having a melting point of 129 ° C. or less is small, specifically, it is 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 (not including polypropylene-based resin of 129 ° C. or less). In the following, the polypropylene-based resin having a melting point of 159 ° C. or more and 175 ° C. or less used in the surface layer B is sometimes referred to as a "high-melting-point polypropylene-based resin", the polypropylene-based resin having a melting point of 130 ° C. or more and 158 ° C. or less is sometimes referred to as a "mid-melting-point polypropylene-based resin", and the polypropylene-based resin having a melting point of 129 ° C. or less is sometimes referred to as a "low-melting-point polypropylene-based resin". The melting points of the polypropylene-based resins used in the surface layer B are rounded to one decimal place and classified as high-melting-point polypropylene-based resins, mid-melting-point polypropylene-based resins, or low-melting-point polypropylene-based resins. The high melting point polypropylene resin, the medium melting point polypropylene resin, and the low melting point polypropylene resin may each be composed of only one type of polypropylene resin, or two or more different types of polypropylene resins.

[0027] When the surface layer B contains 25% by mass or more and 85% by mass or less of a mid-melting point polypropylene resin, adhesion to a vapor deposition layer, a coating layer, etc. can be further improved. When the melting point of the mid-melting point polypropylene resin is 158°C or less, adhesion to a gas barrier layer can be improved. When the melting point is 130°C or more, productivity during film formation can be ensured and roughness of the film surface can be suppressed. The melting point of the mid-melting point polypropylene resin is preferably 134°C or more and 150°C or less, and more preferably 138°C or more and 143°C or less. When the content of the mid-melting point polypropylene resin is 25% by mass or more, adhesion to a vapor deposition layer, a coating layer, etc. can be improved. When the content of the mid-melting point polypropylene resin is 85% by mass or less, productivity during film formation can be ensured and roughness of the film surface can be suppressed. The surface layer B more preferably contains 30% by mass or more and 80% by mass or less of a mid-melting point polypropylene resin, and even more preferably 35% by mass or more and 75% by mass or less.

[0028] On the other hand, the surface layer B preferably contains 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. The surface layer B preferably contains 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.

[0029] With respect to the total resin contained in the surface layer B, the total amount 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%, still more preferably 90 to 100 mass%, particularly preferably 95 to 100 mass%, and most preferably 98 to 100 mass%.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] High-melting-point polypropylene resins, mid-melting-point polypropylene resins, and low-melting-point polypropylene resins are 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. However, 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 %.

[0038] In order to impart lubricity and anti-blocking properties to the surface layer B, the surface layer B contains an anti-blocking agent. Furthermore, the surface layer B 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 various elastomers. These may be sequentially polymerized using a multi-stage reactor, blended with polypropylene resin using a Henschel mixer, or master pellets prepared in advance using a melt kneader may be diluted with polypropylene to a predetermined concentration, or the entire amount may be melt-kneaded in advance before use. With respect to the total resin contained in the surface layer B, the total amount of the high-melting point polypropylene resin and the mid-melting point polypropylene resin is preferably 70 to 100 mass%, 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%.

[0039] 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 content of the antiblocking agent 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. By setting the content within the above ranges, the three-dimensional average roughness and Martens hardness of the surface layer B can be set within the specified ranges described below. At 100 ppm or more, the film has excellent slip properties and anti-blocking properties, whereas at 10,000 ppm or less, problems such as a decrease in light transmittance due to excessive addition of anti-blocking agent, penetration of the anti-blocking agent through the gas barrier layer when laminating the gas barrier layer, and sparseness of the gas barrier layer formed near the surface layer B due to the anti-blocking agent protruding from the surface layer B are unlikely to occur, resulting in a decrease in barrier properties and poor adhesion.

[0040] The dropout rate of the antiblocking agent in the surface layer B 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 guide roll contamination during post-processing such as coating or vapor deposition. Furthermore, the generation of voids due to dropout of the antiblocking agent can be prevented, 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.

[0041] (3) Surface Layer C The surface layer C is an optional layer, and is a layer mainly for exhibiting slip properties and anti-blocking properties. The melting point of the polypropylene-based resin used in the surface layer C is preferably 150°C or higher in order to maintain thermal dimensional stability, mechanical strength, and productivity. Furthermore, polypropylene-based resins with a melting point of 175°C or lower are economically easy to obtain and can prevent the anti-blocking agent from falling off from the surface layer C.

[0042] The surface layer C preferably comprises a polypropylene resin composition containing a polypropylene resin having a melting point of 150°C to 175°C and an antiblocking agent. The polypropylene resin having a melting point of 150°C to 175°C may be a single polypropylene resin, or two or more different polypropylene resins. In the surface layer C, the total content of the polypropylene resin having a melting point of 150°C to 175°C and the antiblocking agent is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass. The melting point of the polypropylene resin used in the surface layer C is preferably 154 to 170°C, more preferably 158 to 165°C.

[0043] The polypropylene-based resin having a melting point of 150°C or higher and 175°C or lower is preferably a polypropylene homopolymer (a polypropylene homopolymer containing absolutely no α-olefin components other than propylene and / or a polypropylene copolymer having constituent units of 1 mol% or less of α-olefin components other than propylene and 99 mol% or more of propylene).

[0044] Various suitable physical properties of polypropylene-based resins having a melting point of 150°C or higher and 175°C or lower are described below. When two or more different polypropylene-based resins having melting points of 150°C or higher and 175°C or lower are used, it is preferable that the mass average values ​​of the physical properties of the respective polypropylene-based resins fall within the numerical ranges described below.

[0045] The weight-average molecular weight (Mw) of the polypropylene resin used in the surface layer C, which has a melting point of 150°C or higher and 175°C or lower, is preferably 180,000 to 500,000. If the Mw is lower than 180,000, the melt viscosity is low, resulting 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 230,000 to 380,000, and particularly preferably 270,000 to 350,000.

[0046] The polypropylene resin used in the surface layer C and having a melting point of 150°C or higher and 175°C or lower preferably has a number average molecular weight (Mn) of 20,000 to 200,000. If Mn is less than 20,000, the melt viscosity is low, resulting in instability during casting and poor film formability. If Mn exceeds 200,000, the heat shrinkage rate at high temperatures may decrease. Mn is more preferably 30,000 to 80,000, even more preferably 40,000 to 70,000, and particularly preferably 50,000 to 60,000.

[0047] The polypropylene resin used in the surface layer C and having a melting point of 150°C or higher and 175°C or lower preferably has an Mw / Mn ratio, which is an index of molecular weight distribution, of 2.8 or higher and 10 or lower, more preferably 3.2 or higher and 8.0 or lower, even more preferably 3.5 or higher and 7.0 or lower, and particularly preferably 4.0 or higher and 6.0 or lower.

[0048] The surface layer C may contain additives or other resins other than polypropylene-based resins having a melting point of 150°C or higher and 175°C or lower. Examples of additives include antiblocking agents, antioxidants, UV absorbers, nucleating agents, adhesives, antifogging agents, flame retardants, inorganic or organic fillers, etc. From the viewpoint of imparting slipperiness and antiblocking properties to the surface layer C, it is preferable that the surface layer C contains an antiblocking agent. Examples of other resins include polyolefin-based resins other than polypropylene-based resins having a melting point of 150°C or higher and 175°C or lower, and various elastomers. These may be sequentially polymerized using a multi-stage reactor, blended with polypropylene resin using a Henschel mixer, master pellets prepared in advance using a melt kneader may be diluted with polypropylene to a predetermined concentration, or the entire amount may be melt-kneaded in advance and used. Of all the resins contained in the surface layer C, the polypropylene-based resin having a melting point of 150°C or higher and 175°C or lower preferably accounts for 80 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and particularly preferably 98 to 100% by mass.

[0049] 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, porous silica preferably has a pore volume of 0.8 mL / g to 2 mL / g, more preferably 1.1 mL / g to 1.8 mL / g. The antiblocking agent contained in surface layer C is preferably the same as the antiblocking agent contained in surface layer B. The particle shape may be spherical or irregular, and irregular shapes are 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 content of the antiblocking agent 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 1,500 ppm to 3,000 ppm, based on the total mass of the surface layer C. By setting the content within the above ranges, the three-dimensional average roughness and Martens hardness of the surface layer C can be set within the specified ranges described below. At 100 ppm or more, the film has excellent slip properties and anti-blocking properties, whereas at 10,000 ppm or less, excessive addition of anti-blocking agent reduces permeability, the anti-blocking agent penetrates the gas barrier layer when laminating the gas barrier layer, and the gas barrier layer formed near surface layer B is less likely to become sparse due to anti-blocking agent protruding from surface layer C, resulting in reduced barrier properties and poor adhesion. The content of the anti-blocking agent in surface layer C is preferably higher than the content of the anti-blocking agent in surface layer B.

[0050] When the surface layer C contains an antiblocking agent, the dropout rate of the antiblocking agent in the surface layer C is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, and particularly preferably 4% or less. A dropout rate of 10% or less can prevent guide roll contamination during post-processing such as coating or vapor deposition. Furthermore, the generation of voids due to dropout of the antiblocking agent can be prevented, and excellent gas barrier properties can be obtained when metal and / or metal oxide are vapor-deposited. The lower limit of the dropout rate is not particularly limited, but is, for example, 0.3% or more.

[0051] (4) Layer Structure and Thickness Structure of Biaxially Oriented Polypropylene Film The biaxially oriented polypropylene film of the present invention has a surface layer B on one side of the base layer A. The surface layer B may be laminated directly on the surface of the base layer A, or another layer may be interposed between the base layer A and the surface layer B. Furthermore, when a surface layer C is present on the other side of the base layer A, the surface layer C may be laminated directly 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 of the present invention may have a two-layer structure consisting of only the surface layer B / base layer A, a three-layer structure consisting of only the surface layer B / base layer A / surface layer C, or a multi-layer structure of four or more layers including layers other than the base layer A, the surface layer B, and the surface layer C. An example of a four-layer structure is surface layer B / intermediate layer D / base layer A / surface layer C. By providing the intermediate layer D, the adhesion between the base layer A and the surface layer B can be further increased.

[0052] The overall thickness of the biaxially oriented polypropylene film of the present invention is preferably 5 to 100 μm, more preferably 10 to 80 μm, and even more preferably 18 to 50 μm. Within the above range, the film has sufficient rigidity and is suitable as a substrate for packaging and industrial use.

[0053] The thickness of the surface layer B 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 adhesion between the surface layer B and the gas barrier layer, making the film suitable for use as a substrate for packaging or industrial applications that require the addition of a gas barrier layer by vapor deposition processing, coating, or the like. If the thickness of the surface layer B is greater than 10 μm, the thickness ratio of the substrate layer A may become relatively low, which may result in a decrease in the rigidity and thermal dimensional stability of the film.

[0054] When the surface layer C is present, the thickness of the surface layer C is preferably 0.3 μm to 10 μm, more preferably 0.5 μm to 5 μm, and even more preferably 0.8 μm to 3 μm. A thickness of 0.3 μm or more makes it easy to ensure the slipperiness and processability of the film. If the thickness of the surface layer C is greater than 10 μm, the thickness ratio of the base layer A may become relatively low, which may result in a decrease in the rigidity and thermal dimensional stability of the film.

[0055] 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.

[0056] The biaxially oriented polypropylene film of the present invention can be obtained by melt-extruding the polypropylene resin compositions constituting each of the base layer A and the surface layer B 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 the transverse direction (TD), and then heat-setting the sheet.

[0057] The melt extrusion temperature is preferably about 200 to 280°C. When layers A and B 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 base layer A and the MFR of surface layer B (hereinafter referred to as MFR difference) be 5.0 g / 10 min or less. If the MFR difference is greater than 5.0 g / 10 min, the layers tend to become disordered, resulting in poor appearance. It is more preferably 4.0 g / 10 min or less, and even more preferably 3.0 g / 10 min or less. Furthermore, when a surface layer C is included, it is preferable that the difference between the maximum and minimum MFRs of the three polypropylene resin compositions constituting the base layer A, surface layer B, and surface layer C be 5.0 g / 10 min or less, and more preferably 3.0 g / 10 min or less.

[0058] The surface temperature of the chill roll is preferably 25 to 50°C, more preferably 30 to 45°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.

[0059] 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.

[0060] 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 vapor-deposited.

[0061] 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. If the MD stretching temperature is further increased, the film may stick to the stretching rolls, making it impossible to stretch.

[0062] 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.

[0063] When the mesopentide fraction of the polypropylene homopolymer constituting the base layer A is not high, the preheating temperature for TD stretching is preferably set 1 to 5°C higher than the stretching temperature. When the mesopentide fraction of the polypropylene homopolymer constituting the base layer A is high, the preheating temperature for TD stretching is preferably set 7 to 20°C higher than the stretching temperature in order to quickly raise the preheating temperature for TD stretching to near the stretching temperature. 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 sufficiently softened and is less likely to break or have a high 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.

[0064] In order 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. At 160°C or higher, the heat shrinkage rate is less likely to increase, and long-term treatment is not necessary to reduce the heat shrinkage rate. The upper limit of the heat setting temperature is preferably 180°C or lower, more preferably 175°C or lower. At 180°C or lower, melting of low-molecular-weight components and reduction in orientation due to recrystallization are less likely to occur, and surface roughness and whitening of the film are less likely to occur.

[0065] 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.

[0066] 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.

[0067] The film thus obtained may be subjected to corona discharge, plasma treatment, flame treatment, etc., as required, and then wound up on a winder to obtain the biaxially oriented polypropylene film roll of the present invention.

[0068] The method for producing the biaxially oriented polypropylene film of the present invention is not limited to the above-mentioned method.

[0069] (5) Various Properties of the Biaxially Oriented Polypropylene Film of the Present Invention (Haze) The haze of the biaxially oriented polypropylene film of the present invention is preferably 8% or less, more preferably 5% or less, even more preferably 4% or less, and particularly preferably 3% or less. Within the above range, the film is easy to use in applications requiring transparency. The 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.

[0070] (Tensile Modulus) The tensile modulus in the longitudinal direction of the biaxially oriented polypropylene film of the present invention 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 in the width direction of the biaxially oriented polypropylene film of the present invention 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 moduli in the longitudinal direction and the width direction of the biaxially oriented polypropylene film of the present invention 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 a strong stiffness, can be used even with a thin film thickness, and ultimately can reduce costs. In addition, the "longitudinal direction" of the biaxially oriented polypropylene film of the present invention is the direction corresponding to the flow direction in the film manufacturing process, and the "width direction" is the direction perpendicular to the flow direction in the film manufacturing process, and the same applies below.

[0071] (Heat Shrinkage Rate) The heat shrinkage rate in the longitudinal direction of the biaxially oriented polypropylene film of the present invention at 150°C is preferably 15.0% or less, more preferably 9.0% or less, even more preferably 7.0% or less, and particularly preferably 5.0% or less. The lower limit of the heat shrinkage rate in the longitudinal direction at 150°C is preferably 0% or more. If the heat shrinkage rate is within the above range, the film can be used in applications where it may be exposed to high temperatures. Even when a gas barrier layer is laminated on the film, the degradation of the barrier property of the gas barrier layer can be suppressed, thereby improving the barrier property of the laminate. The heat shrinkage rate in the width direction of the biaxially oriented polypropylene film of the present invention at 150°C is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 8.0% or less. The lower limit of the heat shrinkage rate in the width direction at 150°C is preferably 0% or more. If the heat shrinkage rate is within the above range, the film can be used in applications where it may be exposed to high temperatures. Even when a gas barrier layer is laminated on the film, the degradation of the barrier property of the gas barrier 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 of the present invention at 150°C is 25.0% or less, preferably 23.0% or less, 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. Within the above range, the film can be used in applications where it may be exposed to high temperatures. Furthermore, even when a gas barrier layer is laminated on the film, deterioration of the barrier property of the gas barrier layer can be suppressed, resulting in improved barrier property of the laminate.

[0072] (Wet tension) The surface wet tension of the surface layer B of the biaxially oriented polypropylene film of the present invention is 36 mN / m or more, preferably 38 mN / m or more, and more preferably 40 mN / m or more. A wet tension of 36 mN / m or more improves adhesion to the gas barrier layer. In order to achieve a wet tension of 36 mN / m or more, it is preferable to perform a physicochemical surface treatment such as corona treatment or flame treatment. In corona treatment, it is preferable to use a preheating roll and a treatment roll and perform discharge in the air. If the wet tension is too high, slip properties and anti-blocking properties may deteriorate, so it is preferably 46 mN / m or less.

[0073] When another material is laminated on the surface layer C, the surface wet tension of the biaxially oriented polypropylene film of the present invention is preferably 36 mN / m or more, more preferably 38 mN / m or more, and even more preferably 40 mN / m or more, similarly to the surface layer B. If the wet tension is too high, slip properties and anti-blocking properties may deteriorate, so it is preferably 46 mN / m or less. When no other material is laminated on the surface of the surface layer C, a wet tension of 32 mN / m or less is preferred in terms of slip properties and anti-blocking properties.

[0074] (Surface Resistivity) The surface resistance of the surface layer B of the biaxially oriented polypropylene film of the present invention 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 such as antistatic agents or impurities, the surface resistance will be less than 14 Log Ω, which may result in poor adhesion. A surface resistance of 14 Log Ω or more is preferred in terms of adhesion to the gas barrier layer. The preferred upper limit of the surface resistance of the surface layer B is not particularly limited, but is 18 Log Ω or less from a manufacturing standpoint.

[0075] The surface resistance of the surface layer C of the biaxially oriented polypropylene film of the present invention 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 such as antistatic agents or impurities, the surface resistance will be less than 14 Log Ω, which may result in poor adhesion. A surface resistance of 14 Log Ω or more is preferred in terms of adhesion. The preferred upper limit of the surface resistance of the surface layer C is not particularly limited, but is 18 Log Ω or less from a manufacturing standpoint.

[0076] (Martens Hardness) The Martens hardness of the surface layer B of the biaxially oriented polypropylene film of the present invention is 248 N / mm ２ or less, preferably 245 N / mm ２ More preferably, it is 230 N / mm ２ More preferably, it is 210 N / mm or less. ２ The Martens hardness of the surface layer B is 248 N / mm ２ or less, the adhesion between the surface layer B and the gas barrier layer is improved. Furthermore, the adhesion is easily improved even if the ratio of the thickness of the surface layer B to the thickness of the entire film is reduced. By using a polypropylene-based resin having a melting point of 130°C or more and 158°C or less in an amount of 25% by mass or more and 85% by mass or less in the surface layer B, the Martens hardness can be reduced to 248 N / mm ２ The Martens hardness can be reduced by adjusting the film-forming conditions, such as by lowering the film stretching ratio, to reduce the degree of oriented crystallization of molecular chains. The lower limit of the Martens hardness of the surface layer B is 150 N / mm ２ It is preferable that the strength is 165 N / mm or more. ２ More preferably, it is equal to or greater than this.

[0077] The Martens hardness of the surface layer C of the biaxially oriented polypropylene film of the present invention is 250 N / mm ２ It is preferable that the strength is equal to or greater than 260 N / mm ２ More preferably, it is 270 N / mm ２ The upper limit of the Martens hardness of the surface layer C is 350 N / mm ２Preferably, less than 300 N / mm ２ The following is more preferable. The Martens hardness of the surface layer B indicates the hardness of the surface layer B measured using a dynamic ultra-microhardness tester under the conditions described in the Examples below. The Martens hardness of the surface layer C is also measured using the same method.

[0078] (Three-dimensional average roughness) The three-dimensional average roughness SRa of the surface layer B of the biaxially oriented polypropylene film of the present invention is preferably 10 nm or more and 100 nm or less, more preferably 13 nm or more and 90 nm or less, even more preferably 15 nm or more and 80 nm or less, particularly preferably 17 nm or more and 70 nm or less, and most preferably 19 nm or more and 50 nm or less. When the three-dimensional average roughness of the surface layer B is 10 nm or more, the film has good slipperiness, and the occurrence of wrinkles can be suppressed when wound into a roll or during post-processing such as vapor deposition. Furthermore, when the three-dimensional average roughness is 100 nm or less, the film has good transparency, and the film is prevented from becoming too slippery when wound into a roll or during post-processing such as vapor deposition, thereby preventing deterioration of workability.

[0079] The three-dimensional average roughness SRa of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 15 nm to 100 nm, more preferably 20 nm to 70 nm, and even more preferably 30 nm to 50 nm. When the three-dimensional average roughness of the 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, when the three-dimensional average roughness is 100 nm or less, the film has good transparency and can suppress the deterioration of workability due to excessive slipperiness when wound into a roll or during post-processing such as vapor deposition.

[0080] The dynamic friction coefficient (B layer / C layer) of the biaxially oriented polypropylene film of the present invention is preferably 0.7 or less, more preferably 0.6 or less, and even more preferably 0.5 or less. If the dynamic friction coefficient is greater than 0.7, the film will have poor slip properties, which may cause wrinkling or blocking when wound into a roll or during post-processing such as vapor deposition.

[0081] [Gas Barrier Layer] In the present invention, the laminate film must have a gas barrier layer on the surface of the base layer of the film. As the gas barrier layer, it is preferable to laminate either a coating layer D containing an organic substance as the main component or an inorganic thin film layer E containing an inorganic substance as the main component, as described below. Furthermore, in order to enhance the barrier properties of the gas barrier layer, an anchor coat layer F or a protective layer G, as described below, can also be laminated in combination.

[0082] [Coating Layer D] In the present invention, a coating layer D may be provided as a gas barrier layer. However, in the present invention, it is necessary to design the coating layer D with due consideration given to the environmental impact, such as increased costs due to the additional steps involved and difficulty in recycling depending on the coating layer's thickness.

[0083] The coating weight of the coating layer D is 0.10 to 3.0 (g / m ２ The 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 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 film thickness of coating layer D 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.

[0084] The resin composition used for the coating layer D formed on the surface of the laminate film of the present invention 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 hydrogen-bonded structures. 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 viewpoint of coating workability. A saponification degree of less than 90% does not provide sufficient oxygen gas barrier properties under high humidity conditions, while a saponification degree of more than 99.7% makes it difficult to prepare the aqueous solution and prone to gelation, making it unsuitable for industrial production. Therefore, a saponification degree of 90 to 99.7% is preferred, and more preferably 93 to 99%. In the present invention, various copolymerized or modified polyvinyl alcohol polymers, such as polyvinyl alcohol polymers copolymerized with ethylene and silanol-modified polyvinyl alcohol polymers, can also be used within the scope of not impairing processability or productivity.

[0085] The coating layer D of the present invention 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 an 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.

[0086] Furthermore, inorganic layered compounds containing redox-active metal ions, especially iron ions, are preferred. Among these, montmorillonite, a type of smectite, is preferred from the viewpoints of coating suitability and gas barrier properties. Known montmorillonites that have been used in gas barrier agents can be used. For example, compounds represented by the following general formula: (X,Y)2-3ZO 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.

[0087] 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.

[0088] The blending ratio of the resin composition to the inorganic layered compound in the coating layer of the present invention is preferably 75 / 25 to 35 / 65 (wt%), more preferably 70 / 30 to 40 / 60 (wt%), and even more preferably 65 / 35 to 45 / 55 (wt%). If the 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.

[0089] In order to improve the cohesive strength and moist heat resistant adhesion of the film, various crosslinking agents may be blended into the coating layer D of the present invention, as long as they do 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 for a crosslinking reaction with a resin composition or an inorganic thin film layer having a hydroxyl group, 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. Additionally, oxazoline compounds, carbodiimide compounds, epoxy compounds, and the like may be used in combination as crosslinking agents. However, when emphasis is placed on recyclability, the amount of crosslinking agent added must be considered.

[0090] When a crosslinking agent is incorporated, its amount in the coating layer 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 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.

[0091] In the present invention, 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 also affect the surface irregularities, which may lead to poor appearance in subsequent printing processes, etc. The haze can be adjusted by the composition ratio of the coating layer D, solvent conditions, film thickness, etc. Here, the haze was evaluated in accordance with JIS K7136 using a turbidity meter (NDH2000, manufactured by Nippon Denshoku Corporation).

[0092] 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.

[0093] 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 may not be sufficiently dried. If the pre-drying temperature is higher than 110°C, the coating layer may dry before it has spread, resulting in a poor appearance.

[0094] 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 will 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.

[0095] 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, care must be taken 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 promoting the formation of coating layer D.

[0096] [Inorganic Thin Film Layer E] In the present invention, the film may have an inorganic thin film layer E on the surface of the base layer as a gas barrier layer. The inorganic thin film layer E is 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. Among these, inorganic oxides are preferred, and 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 does not include SiO or SiO ２ and various silicon oxides such as AlO and Al ２ O ３ and the like, or mixtures thereof.

[0097] 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.

[0098] 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 O３ or a mixture of SiO ２ 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.

[0099] When metal or inorganic oxide is vapor deposited, it is preferred to vapor deposit it on the side of the biaxially oriented polypropylene film used in the present invention which has the lesser surface roughness.

[0100] [Anchor Coat Layer F] In the present invention, an anchor coat layer F may be provided as an auxiliary layer to ensure 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 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 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.

[0101] When only the anchor coat layer F is laminated, the gas barrier auxiliary property of the film is such that the oxygen permeability in an environment of 23°C x 65% RH is 10,000 ml / m 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, making it difficult to use in applications where high gas barrier properties are required.

[0102] In 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 less than 0.85 g / m 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 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.

[0103] Resin compositions used in the anchor coat layer F of the present invention include urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based, and other resins to which epoxy-based, isocyanate-based, melamine-based, and other curing agents have been added. They may also contain crosslinking agents such as silicon-based crosslinkers, oxazoline compounds, carbodiimide compounds, and epoxy compounds. 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 the present invention, it is particularly preferred to include a polyurethane composed of polyester and isocyanate as constituent components. Furthermore, the addition of a silicon-based crosslinking agent is even more preferred from the viewpoint of improving adhesion.

[0104] In terms of gas barrier assisting properties, the urethane resin used in the anchor coat layer F of the present invention is preferably a urethane resin containing an aromatic or araliphatic diisocyanate component as a main constituent. Among these, it is particularly preferable to contain a metaxylylene diisocyanate component. 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.

[0105] In the present invention, the proportion of aromatic or araliphatic diisocyanate in the urethane resin used in the anchor coat layer F is preferably in the range of 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.

[0106] The urethane resin used in the anchor coat layer F of the present invention may be blended with various crosslinking agents in order to improve the cohesive strength of the film and the adhesion resistance to wet heat.Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc.Among them, silicon-based crosslinking agents are particularly preferred, since blending a silicon-based crosslinking agent can improve the water-resistant adhesion, particularly with the inorganic thin film layer.Other crosslinking agents may also be used in combination with oxazoline compounds, carbodiimide compounds, epoxy compounds, etc.

[0107] 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.

[0108] The silicon-based crosslinking agent is preferably added to the coating layer 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 remain, 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.

[0109] The polyester resin used in the anchor coat layer F of the present invention 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 necessary to use a polyester polyol that is predominantly alcohol-terminated.

[0110] The Tg of the polyester resin used in the anchor coat layer F of the present invention 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.

[0111] The polyester resin used in the anchor coat layer F of the present invention is prepared by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The polycarboxylic acid component of the polyester resin used in the present invention is characterized by containing at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. Ortho-orientation improves solubility in solvents, enabling uniform coating on the substrate. 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 wet heat treatment and suppressing oligomer formation. Examples of aromatic polycarboxylic acids or anhydrides with carboxylic acids substituted at the ortho positions 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, or a naphthyl group. Furthermore, polyester polyols having a content of these in an amount 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, which is essential for a coating material.

[0112] In the present invention, other polycarboxylic acid components may be copolymerized within the range that does not impair the effects of the invention. 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 organic solvent solubility and gas barrier properties.

[0113] The polyhydric alcohol component of the polyester used in the anchor coat layer F of the present invention 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.

[0114] In the present invention, it is preferable to use the polyhydric alcohol component described above, but other polyhydric alcohol components may also be copolymerized within the scope of not impairing the effects of the present invention. 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.

[0115] Examples of catalysts that can be used in the reaction to obtain the polyester of the present invention include tin-based catalysts such as monobutyltin oxide and dibutyltin oxide, titanium-based catalysts such as tetraisopropyltitanate and tetrabutyltitanate, and acid catalysts such as zirconia-based catalysts such as tetrabutylzirconate. It is preferable to use a combination of the above-mentioned titanium-based catalysts, such as tetraisopropyltitanate and tetrabutyltitanate, which have high activity in esterification reactions, with the above-mentioned zirconia catalyst. The amount of the catalyst used is 1 to 1,000 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 1,000 ppm, problems such as inhibition of the urethanization reaction may occur when an isocyanate curing agent is used.

[0116] In the present invention, 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 such as the liquid being unable to be reused after mixing with the curing agent, and a curing (aging) process being required after coating. Examples of advantages include the fact that, as a simple overcoat varnish, there is no risk of thickening of the coating liquid, coating production is easy to manage, the coating liquid can be diluted and reused, and a curing process (so-called aging process) is not required. 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.

[0117] 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 it is a coating on a film. In this case, the resin component of the coating material must be polyester polyol. On the other hand, when an epoxy compound is used as the curing agent, polyester polycarboxylic acid is required. 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 and retort packaging. On the other hand, there are problems with this, such as the liquid not being reusable after mixing with the curing agent, and the need for a curing (aging) process after coating.

[0118] When the polyester has hydroxyl groups, the polyisocyanate compound used in the present invention reacts at least partially to form a urethane structure, thereby making the resin component highly polar and causing aggregation between polymer chains, thereby further strengthening 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 used in the present invention may be a diisocyanate, a trivalent or higher polyisocyanate, a low-molecular-weight compound, or a high-molecular-weight compound, but it is preferable to contain an aromatic ring or an aliphatic ring as part of the 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.

[0119] 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, offline coating and in-line coating methods are preferred. For example, in the case of an in-line coating method carried out in the process of producing a biaxially oriented polypropylene film, the conditions for drying and heat treatment during coating depend on the coating thickness and the conditions of the equipment, but it is preferable to feed the film to a stretching process in the perpendicular direction immediately after coating and dry it in the preheating zone or stretching zone of the stretching process. In such cases, a temperature of about 50 to 250°C is usually preferred.

[0120] 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.

[0121] 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 may not be sufficiently dried. On the other hand, if the drying temperature exceeds 145°C, the film may be overheated, becoming brittle or shrinking, 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 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 the formation of the anchor coat layer.

[0122] [Protective Layer G on Inorganic Thin Film] In the present invention, a protective layer G may be provided on the inorganic thin film layer, 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 a protective layer by coating a specific resin composition for protective layer, which will be described later, on the metal oxide layer, the resin in the resin composition for protective layer penetrates into the defects in 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 itself, the gas barrier performance of the laminate film is also improved.

[0123] In the present invention, the amount of the protective layer G attached is 0.10 to 0.40 (g / m ２) is preferable. This allows the protective layer 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 to be applied 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 becomes insufficient and the uniformity of the protective layer also decreases, which may result in unevenness or defects in the coat appearance and insufficient gas barrier properties and adhesiveness. ２ If the thickness is less than 1 / 2 mm, sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0124] The resin composition used for the protective layer G formed on the surface of the inorganic thin film layer of the present invention 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.

[0125] 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.

[0126] 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 can result in insufficient drying of the protective layer, or the formation of the protective layer cannot 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 can 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 at a relatively low temperature of 90 to 110°C immediately after application, and then dry the protective layer at 130°C or higher, as this results in a uniform and transparent film. In addition to drying, additional heat treatment at as low a temperature as possible can also be more effective in promoting the formation of the protective layer.

[0127] [Other Films] In the present invention, other films may be laminated to impart functionality. The other films used in the present invention are, for example, films obtained by melt-extruding plastics and, as necessary, stretching them in the longitudinal direction and / or the width direction, cooling, and heat setting. Examples of plastics include polyamides typified by nylon 4.6, nylon 6, nylon 6.6, and nylon 12, polyesters typified by polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, as well as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, wholly aromatic polyamides, polyamideimides, polyimides, polyetherimides, polysulfones, polystyrenes, and polylactic acids.

[0128] The other films in the present invention 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, in terms of recyclability, the mono-material ratio of the packaging material must be taken into consideration.

[0129] The other film in the present invention 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.

[0130] [Adhesive Layer] The adhesive layer used in the present invention can be a general-purpose laminating adhesive. For example, solvent-free, water-based, or hot-melt adhesives based on 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 can be used. Among these, adhesives obtained by crosslinking polyurethane, polyester, or polyamine resins are preferred from the standpoints of heat resistance, flexibility that can accommodate dimensional changes in each substrate, and improved gas barrier properties of the adhesive itself. The use of these adhesives can improve barrier performance. However, caution is required because if the film becomes too hard due to crosslinking, there is a risk of reduced barrier performance after bending. 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 adhesiveness, 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 adhesive strength decreases. Furthermore, if the coating weight exceeds 8 μm, it takes a long time for the film to completely cure, unreacted material is likely to remain, and adhesive strength decreases.

[0131] [Printed Layer] Furthermore, the packaging material of the present invention may have at least one printed layer laminated between the laminated film and the film to be laminated or on the outside thereof.

[0132] As the printing ink for forming the printed layer, aqueous and solvent-based resin-containing printing inks are preferably used. Among these, aqueous inks are particularly preferred from an environmental perspective. When using aqueous inks, it is necessary that the printed layer does not repellent (printability) and that it has sufficient adhesion to the film. The laminate of the present invention has excellent printability and adhesion with aqueous inks. 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 even 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.

[0133] [Heat-sealable laminate] When the laminate of the present invention is used for packaging, etc., it can be processed into a packaging material as a heat-sealable laminate laminated with a 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 in the form of unstretched films or uniaxially stretched films made of low-density polyethylene, linear low-density polyethylene, or polypropylene are preferred. In terms of ease of recycling, polypropylene is particularly preferred.

[0134] The surface to which the heat-sealable film is laminated may be either the surface layer B side or the surface layer C side. The heat-sealable film is preferably laminated via an adhesive layer. As the adhesive, the above-mentioned ester-based adhesives, urethane-based adhesives, acrylic-based adhesives, polyethyleneimine-based adhesives, etc. can be used. As the lamination method, a dry lamination method, an extrusion lamination method, a co-extrusion method, etc. can be used.

[0135] [Properties of the Laminate] As a packaging material, the laminate of the present invention can have any conceivable laminate configuration. From the standpoint of environmental impact, it is preferable to use fewer materials and fewer lamination processes. On the other hand, from the standpoint of imparting functionality such as further improvement in barrier properties, printability, toughness, and stiffness, a laminate laminated with another biaxially oriented polypropylene film is also one preferred configuration. In this case, by laminating a printing layer on the front biaxially oriented polypropylene film, there is also the advantage that printing on a film having a gas barrier layer is not necessary. Other suitable configurations include laminating the laminate with a white base film to improve concealment properties, or with an ultraviolet-blocking film to provide light-blocking properties.

[0136] The laminate of the present invention, when bonded to another film via an adhesive to form a packaging material, has an oxygen permeability of 100 ml / m under conditions of 23°C x 65% RH. 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 ２ If the viscosity exceeds d MPa, it becomes difficult to use the film in applications that require high gas barrier properties.

[0137] The laminate of the present invention, when bonded to another film via an adhesive to form a packaging material, has a water vapor permeability of 3.0 g / m under conditions of 40°C x 90% RH. 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 / m２ 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.

[0138] The laminate strength of the biaxially oriented polypropylene film of the present invention having a gas barrier layer, as measured by the method described below, 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.

[0139] The laminate of the present invention is less likely to wrinkle at the sealed portion even when the heat-sealing temperature is high when processed into a packaging bag. Since 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 of the present invention is 0.0% or more and 25.0% or less, even when the temperature of the seal bar is increased, there is little wrinkling or deformation at the sealed portion, and the bag production speed can be increased.

[0140] An example of a laminate configuration using the laminate 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 printing layer and a heat-sealable film such as an unstretched polypropylene film or an unstretched 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. It is also possible to form a laminate by bonding a heat-sealable film such as an unstretched polypropylene film or an unstretched linear low-density polyethylene film to a laminate of the present invention provided with a printing layer as a functional layer. Examples include laminates used as a surface printing substrate, such as (printed layer / OPP*) / adhesive layer / (CPP or LLDPE). 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

[0141] 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.

[0142] 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.

[0143] The contents to be filled into the packaging bag using the packaging material of the present invention are not particularly limited, and may be liquid, powder, or gel. The contents may also be food or non-food.

[0144] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0145] (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, in 5) to 17), the physical properties of the biaxially oriented polypropylene film, and in 18) to 23), the physical properties of the biaxially oriented polypropylene film laminated with other layers such as a gas barrier layer were measured.

[0146] 1) Melting Point A differential scanning calorimeter (DSC) manufactured by SII was used. 10 mg of a sample was packed into an aluminum pan and set therein. The sample was melted at 230°C for 5 minutes under a nitrogen atmosphere, 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.

[0147] 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.

[0148] 3) Melt flow rate (MFR) Measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kgf.

[0149] 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

[0150] 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 ｉ ２ ) / 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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).

[0157] 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.

[0158] 12) Martens Hardness The resulting film was cut into approximately 2 cm squares to prepare samples. The surface opposite the measurement surface was fixed to a glass plate approximately 1 mm thick with an adhesive, and then the sample was left to stand for 12 hours in an atmosphere of 23°C and 50% relative humidity to condition the humidity. Using a dynamic ultra-microhardness tester (DUH-211, manufactured by Shimadzu Corporation) in accordance with ISO 14577-1 (2002), the Martens hardness of surface layer B and surface layer C of the sample was measured under the following measurement conditions. The measurement was performed 10 times, changing the position of the film, and the average of 8 points excluding the maximum and minimum values ​​was calculated. <Measurement Conditions> (Settings) Measurement environment: Temperature 23°C, relative humidity 50% Test mode: Load-unload test Indenter used: Triangular pyramidal indenter with 115° edge angle Indenter elastic modulus: 1.140 x 106 N / mm ２ Indenter Poisson's ratio: 0.07 Cf-Ap, As correction: Yes (Conditions) Test force: 0.10 mN Load rate: 0.0050 mN / sec Load holding time: 5 sec Unloading holding time: 0 sec

[0159] 13) 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

[0160] 14) 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.). The number of all antiblocking agents 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 from film) / (total number of observed antiblocking agents and number of traces of antiblocking agent removed from film) x 100

[0161] 15) 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) in an atmosphere of 23°C and relative humidity of 50%.

[0162] 16) Guide Roll Staining For the film rolls obtained in the Examples and Comparative Examples, a 500 m length of film was passed through a slitter (NS-SLITTER FN-105 manufactured by Nishimura Mfg. Co., Ltd.) and rewound, after which the staining (degree of whitening) of the guide roll due to the antiblocking agent falling off from the B layer side or the C layer side was qualitatively compared and evaluated, with a rating of A being a pass. A: No staining of the guide roll. B: Slight partial staining of the guide roll. C: Staining over the entire surface of the guide roll.

[0163] 17) 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 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.

[0164] 18) Composition and film thickness of inorganic thin film layer C on biaxially oriented polypropylene film The film thickness composition of the laminates (after thin film lamination) obtained in the examples and comparative examples was measured using a fluorescent X-ray analyzer ("Supermini 200" manufactured by Rigaku Corporation) based on a previously prepared calibration curve. The excitation X-ray tube conditions were 50 kV and 4.0 mA.

[0165] 19) Adhesion amount of coating layer D, anchor coat layer E, and protective layer F on biaxially oriented polypropylene film In each example and comparative example, each laminated film obtained at the stage where a predetermined coating layer D, anchor coat layer E, and protective layer F were laminated on a biaxially oriented polypropylene film was used as a sample, and a 100 mm x 100 mm test piece was cut out from this sample, and the coating layer was wiped off with either water, ethanol, or acetone, and the adhesion amount was calculated from the change in mass of the film before and after wiping.

[0166] 20) Preparation of packaging material for evaluation When the number of films to be bonded, including the laminate, is two in total, a polyurethane adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) is applied to the propylene film or laminate of the present invention so that the thickness after drying at 80 ° C is 3 μm, and then unstretched polypropylene film P1128-30 μm (CPP1) is 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 laminate laminate for evaluation. On the other hand, when the number of films to be bonded, including the laminate, is three in total, a polyurethane adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) is applied to OPP-A (polypropylene film P2171-20 μm manufactured by Toyobo Co., Ltd.) so that the thickness after drying at 80 ° C is 3 μm, and then the propylene film or laminate of the present invention is dry-laminated on a metal roll heated to 60 ° C. to obtain a winding roll. The same adhesive was applied to this roll so that the thickness after drying at 80°C would be 3 μm, and then an unstretched polypropylene film P1128-30 μm (CPP1) was dry-laminated as a heat-sealable resin on a metal roll heated to 60°C, followed by aging at 40°C for 2 days (48 hours) to obtain a packaging material for evaluation.

[0167] 21) Evaluation method for oxygen transmission rate of packaging material The oxygen transmission rate of the packaging material prepared in (20) above was measured in accordance with JIS-K7126 Method B using an oxygen transmission rate measuring device (OX-TRAN (registered trademark) 2 / 22 manufactured by MOCON Co., Ltd.) under an atmosphere of a temperature of 23°C and a humidity of 65% RH. The measurement of oxygen transmission rate was carried out in the direction in which oxygen permeated from the biaxially oriented polypropylene film side of the packaging material to the heat seal layer side.

[0168] 22) Evaluation method for water vapor permeability of packaging material The water vapor permeability of the packaging material prepared in (20) above was measured in accordance with JIS-K7129 Method B using a water vapor permeability measuring device ("PERMATRAN-W 3 / 33MG" manufactured by MOCON Co., Ltd.) 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 biaxially oriented polypropylene film side to the heat-sealable layer side.

[0169] 23) Laminate strength of packaging material The packaging material prepared in (20) above was cut into a width of 15 mm and a length of 200 mm to prepare a test piece, and the laminate strength was measured using a Tensilon universal testing machine ("Tensilon UMT-II-500" manufactured by Toyo Baldwin Co., Ltd.) under conditions of a temperature of 23°C and a relative humidity of 65%. The laminate strength was measured at a tensile speed of 200 mm / min, and the strength was measured when the laminate layer and the heat-sealable resin layer of each laminate obtained in the Examples and Comparative Examples were peeled at a peel angle of 90 degrees. The seal appearance was evaluated relative to the other: A: a seal without wrinkles, B: a seal with partial wrinkles, and C: a seal with wrinkles over the entire surface.

[0170] The various biaxially oriented polypropylene films and gas barrier layers used in the examples and comparative examples are listed below.

[0171] (Film Raw Material Resins) Details of the polypropylene resins PP-1 to PP-6 used in the following examples and comparative examples are shown in Table 1. The molar ratio of ethylene to butene, the copolymerization components contained in PP5, was ethylene:butene = 4:3. The antiblocking agent masterbatch (hereinafter referred to as MB-1) used PP-3 shown in Table 1 as the polypropylene resin, and the antiblocking agent (AB agent) was one of porous silica particles with an average particle size of 2.9 μm and a pore volume of 1.6 mL / g, poreless silicone particles with an average particle size of 2.0 μm, or poreless crosslinked polymethyl methacrylate (PMMA) particles with an average particle size of 1.4 μm. The types of antiblocking agents used in the examples and comparative examples are shown in Table 2. In all examples and comparative examples, the content of the antiblocking agent in MB-1 was 5.0 mass%.

[0172]

[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, 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 surface layer C, a blend of 25% by mass of PP-3, 70% by mass of PP-4, and 5% 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 surface layer B was cooled and solidified so that it 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 at 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 three-layer laminate consisting of surface layer B / base layer A / surface layer C. The surface of the surface layer B of the laminate was 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 / 17.7 μm / 1.0 μm).

[0174] (Biaxially oriented polypropylene films (OPP2 to 4, 6, 7, 10, 11)) Biaxially oriented polypropylene films were obtained under the same conditions as for OPP1, except that the raw material composition of surface layer B was changed as shown in Table 2. For OPP4 and OPP6, the raw material composition of surface layer C was also changed as shown in Table 2.

[0175] (Biaxially oriented polypropylene film (OPP5)) A biaxially oriented polypropylene film was obtained under the same conditions as OPP1, except that the surface layer C was also subjected to a corona treatment.

[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 the raw material composition of surface layer B was changed as shown in Table 2, and PP-5, a polypropylene resin with a melting point of 140° C., was changed to PP-6, a polypropylene resin with a melting point of 125° 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 obtain a stable biaxially oriented polypropylene film.

[0177] (Biaxially oriented polypropylene film (OPP9)) The raw material composition was the same as that of OPP8, and the production conditions were the same as those of OPP1, except that the longitudinal stretching temperature was lowered by 10°C to 125°C and the production conditions were changed as shown in Table 2, to obtain a biaxially oriented polypropylene film.

[0178] (Biaxially oriented polypropylene film (OPP12)) A biaxially oriented polypropylene film was obtained under 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] (Biaxially oriented polypropylene film (OPP13)) A biaxially oriented polypropylene film was obtained under the same conditions as OPP1, except that the surface layer B was not subjected to corona treatment.

[0180] (Biaxially oriented polypropylene film (OPP14)) A biaxially oriented polypropylene film was obtained under the same conditions as OPP1, except that the antiblocking agent contained in surface layer B and surface layer C was changed from the silica particles to the silicone particles.

[0181] (Biaxially oriented polypropylene film (OPP15)) A biaxially oriented polypropylene film was obtained under the same conditions as OPP1, except that the antiblocking agent contained in surface layer B and surface layer C was changed from the silica particles to the crosslinked polymethyl methacrylate particles.

[0182] The raw material composition of each layer of the film, the thickness of each layer, and the film production conditions are shown in Table 2, and various physical properties and evaluation results are shown in Table 3.

[0183]

[0184]

[0185] The biaxially oriented polypropylene films obtained in OPPs 1 to 5 had minimal contamination of the guide rolls during post-processing, and the resulting film rolls had few wrinkles. In contrast, the film of OPP 6 had low lamination strength due to a low blending amount of polypropylene resin with a melting point of 130°C or higher and 158°C or lower in the surface layer B. The film of OPP 7 had a high blending amount of polypropylene resin with a melting point of 130°C or higher and 158°C or lower in the surface layer B, which resulted in unstable longitudinal stretching and poor film formability. The appearance of the biaxially oriented polypropylene film was poor due to the occurrence of stretching unevenness on the longitudinal stretching rolls. Therefore, although the physical properties of the biaxially oriented polypropylene film were measured, evaluations of lamination, coating, and vapor deposition processes were not performed because it was expected that these processes would be significantly poor. OPP8 film was made by replacing PP-5, a polypropylene-based resin with a melting point of 140°C, in the resin composition of OPP1 with PP-6, a polypropylene-based resin with a melting point of 125°C. This resulted in even more unstable longitudinal stretching and inferior film-forming properties than OPP7. Biaxially oriented polypropylene film could not be obtained stably, and stretching irregularities occurred frequently on the longitudinal stretching rolls, resulting in very poor film appearance. Therefore, physical property measurements and processing evaluation of the biaxially oriented polypropylene film were not performed. Unlike OPP8, OPP9 was able to obtain a biaxially oriented polypropylene film by lowering the longitudinal stretching temperature, but the antiblocking agent dropout rate was poor and guide roll staining was observed. OPP10 had low laminate strength because the surface layer B did not contain a polypropylene resin with a melting point of 130°C or higher and 158°C or lower. In OPP11, the amount of antiblocking agent blended in surface layer B and surface layer C was small, so the three-dimensional average roughness of both surface layers was very small, and the film roll wrinkled when it was wound up. In OPP12, the raw material for base layer A was a polypropylene resin with a melting point of 159°C, so the sum of the heat shrinkage rates at 150°C was high. In OPP13, surface layer B was not corona treated, so the laminate strength was low.In OPP14 and 15, the antiblocking agent contained in surface layer B and surface layer C was an antiblocking agent with a pore volume of zero, and therefore the rate of detachment of the antiblocking agent from surface layer B and surface layer C increased, resulting in contamination over the entire surface of the guide roll.

[0186] (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 liquid used in Examples 1 and 2 is shown in Table 4.

[0187] [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, and a nearly transparent polyvinyl alcohol solution (PVA solution) with a solids content of 10% was obtained.

[0188] [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%.

[0189] [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.

[0190] [Coating of Coating Liquid 1 on a Film (Laminating of Coating Layer 1)] The coating liquid prepared above was applied to the corona-treated surface of the surface layer B of OPP1 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 ２Thereafter, a post-heat treatment was carried out at 40° C. for 2 days (48 hours). In this manner, a laminated film provided with a coating layer 1 was produced.

[0191] [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.

[0192] [Coating of Coating Liquid 2 onto Film (Laminating of Coating Layer 2)] The coating liquid prepared above was applied to the corona-treated surface of the surface layer B of OPP1 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 laminated film provided with a coating layer D-2 was produced.

[0193] (Inorganic Thin Film Layer E) The inorganic thin film layer E used in each example and comparative example was prepared as follows. The inorganic thin film layer E used in examples 3 to 11 and comparative examples 2 to 6 was shown in Table 4.

[0194] (Formation of Inorganic Thin Film Layer E-1 (Vapor Deposition 1)) As the inorganic thin film layer E-1, metallic aluminum was vapor-deposited onto the surface layer B of a biaxially oriented polypropylene film (OPP1) (Example 3). Using a small vacuum vapor deposition apparatus (VWR-400 / ERH manufactured by ULVAC KIKO Co., Ltd.), the pressure was reduced to 10 Pa or less, and then aluminum foil with a purity of 99.9% was placed on a Nilaco vapor deposition source CF-305W from below the substrate, and metallic aluminum was heated and evaporated to form a metallic aluminum film with a thickness of 70 nm on the film.

[0195] (Formation of inorganic thin film layer E-2 (vapor deposition 2)) Silicon oxide was vapor-deposited onto the surface layer B of a biaxially oriented polypropylene film (OPP1) to form the inorganic thin film layer E-2 (Example 4). Using a small vacuum vapor deposition apparatus (VWR-400 / ERH, manufactured by ULVAC KIKO Co., Ltd.), the pressure was reduced to 10 Pa or less, and silicon oxide was then placed in a Nilaco vapor deposition source B-110 from below the substrate and evaporated by heating, forming a silicon oxide film with a thickness of 40 nm on the film.

[0196] (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 the surface layer B of the biaxially oriented polypropylene film (Example 5, Comparative Examples 2 and 3) or on the anchor coat layer (Examples 6 to 11, Comparative Examples 4 to 6). The vapor deposition source was granular SiO 2 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 composite oxide layer had a thickness of 20 nm. ２ / Al ２ O ３ The mass ratio was 70 / 30.

[0197] (Anchor Coat Layer F) The following describes the method for producing the anchor coat layer F used in Examples 6 to 11 and Comparative Examples 4 to 6. [Polyester Resin (a)] As the polyester component, polyester polyol (DF-COAT GEC-004C manufactured by DIC Corporation: solid content 30%) was used.

[0198] [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.

[0199] [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.

[0200] [Coating Liquid 1 for Anchor Coat Layer F-1] A solution (15% by mass) of silane coupling agent (c) dissolved in acetone and isocyanate (b) were mixed in the following ratio and stirred for 10 minutes using a magnetic stirrer. The resulting 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 Isocyanate (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

[0201] (Coating of the coating liquid onto the film (lamination of anchor coat layer)) Coating liquid 1 was applied onto the corona-treated surface of the surface layer B of the biaxially oriented polypropylene film by gravure roll coating, and the film was pre-dried at 95°C for 4 seconds, followed by final drying 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 / m ２ Thereafter, a post-heat treatment was carried out at 40° C. for 4 days (96 hours) to obtain the desired laminated film.

[0202] (Protective Layer G) The method for producing the protective layer G used in Example 8 is described below. [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 ２The 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 above-mentioned Coating Solution 1 was applied to the inorganic thin film layer on a biaxially oriented polypropylene film by gravure roll coating, and dried in a dry oven at 120°C for 10 seconds to obtain Protective Layer 1. The protective layer coating weight 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 laminated film provided with a protective layer was produced.

[0203] In this manner, laminated polyolefin films having a coating layer, an anchor coat layer, an inorganic thin film layer, or a protective layer on each film were prepared.

[0204] In each example and comparative example, each film was used and multiple films were bonded together with an adhesive by the dry lamination method described above to obtain packaging materials having the configurations shown in Table 4. Various evaluations were also carried out on the resulting packages. The results are shown in Table 4.

[0205]

[0206] The laminate of the present invention has excellent thermal dimensional stability and mechanical strength, and is easy to work with when forming a vapor-deposited layer or coating layer on the biaxially oriented polypropylene film, and has excellent adhesion to the vapor-deposited layer or coating layer. It is particularly suitable when a layer made of metal and / or metal oxide is formed on the biaxially oriented polypropylene film of the present invention, since a film with high gas barrier properties can be obtained. Such processed films are industrially useful and can be used for food packaging, labels, industrial films, etc.

Claims

1. A laminate comprising a biaxially oriented polypropylene film having a surface layer B made of a polypropylene resin composition on one side of a base layer A made of a polypropylene resin composition, and a gas barrier layer provided on said surface layer B, characterized in that the following (1) to (5) are satisfied: (1) The Martens hardness of said surface layer B is 248 N / mm ２ (2) The wetting tension of the surface layer B is 36 mN / m or more. (3) 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. (4) The surface layer B contains an antiblocking agent, and the rate of dropout of the antiblocking agent is 10% or less. (5) The three-dimensional average roughness SRa of the surface layer B is 10 nm or more.

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

3. A laminate according to claim 1 or 2, wherein the surface layer B contains 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 according to claim 1 or 2, wherein the biaxially oriented polypropylene film has a surface layer C on the other side of the base layer A, and the surface layer C is made of a polypropylene resin composition containing an antiblocking agent.

5. The laminate according to claim 4, wherein the three-dimensional average roughness SRa of the surface layer C is 15 nm or more, and the rate of the antiblocking agent falling off from the surface layer C is 10% or less.

6. The laminate according to claim 4, wherein the surface layer C has a wetting tension of 36 mN / m or more.

7. The laminate according to claim 1 or 2, wherein the gas barrier layer is an inorganic thin film layer made of one material selected from the group consisting of aluminum, aluminum oxide, silicon oxide, and a composite oxide of silicon oxide and aluminum oxide.

8. The laminate according to claim 1 or 2, wherein the gas barrier layer is a coating layer having one or more materials selected from the group consisting of polyvinyl alcohol resin, polyester resin, polyurethane resin, and inorganic layered compound.

9. The laminate according to claim 1 or 2, characterized in that an anchor coat layer is laminated between the biaxially oriented polypropylene film and the gas barrier layer.

10. The laminate according to claim 1 or 2, wherein a protective layer is laminated on the gas barrier layer.

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

12. A packaging material comprising the laminate of claim 1 or 2.

13. The packaging material according to claim 12, wherein a heat-sealable polyolefin film is laminated on the outermost surface of the packaging material.

14. The packaging material according to claim 13, wherein a stretched polyolefin film or stretched polyester film is laminated on the side opposite to the heat-sealable polyolefin film of the laminate.

15. The packaging material according to claim 12, wherein a barrier adhesive layer is laminated on the gas barrier layer.

16. A packaging bag made using the packaging material according to claim 12.

17. A package in which an item is packaged using the packaging material according to claim 12 or the packaging bag according to claim 16.