Laminated film, laminate, and packaging material

Abstract

To provide a laminated film which is excellent in oxygen and water vapor barrier property even after retort treatment, and has such adhesion as to prevent in delamination after the retort treatment.SOLUTION: There is provided a laminated film in which an anchor coat layer and an inorganic thin film layer are laminated in this order on a surface layer (B) of a base material film in which a surface layer (C), a base material layer (A) and the surface layer (B) are laminated in this order, with or without another layer interposed therebetween, wherein the surface layer (B) is formed of a resin composition containing two or more resins, a deposition amount of the anchor coat layer is less than 0.50 g / m2, and a moisture content of the laminated film is 0.2 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a packaging material that maintains excellent gas barrier properties and adhesive strength even after being subjected to moist heat treatment such as boiling sterilization or retort sterilization. The present invention also relates to a laminate that is excellent in material recyclability and a packaging material using the same. [Background technology]

[0002] Packaging materials used for food, pharmaceuticals, etc. are required to have gas barrier properties, i.e., the ability to block gases such as oxygen and water vapor, in order to prevent oxidation of proteins and fats, preserve flavor and freshness, and maintain the efficacy of pharmaceuticals. Furthermore, gas barrier materials used in solar cells, organic electroluminescence (EL) and other electronic devices, and electronic components, require even higher gas barrier properties than food packaging.

[0003] Gas barrier laminate films, which have a thin metal film such as aluminum or a thin inorganic oxide film such as silicon oxide or aluminum oxide formed on the surface of a plastic substrate film, have conventionally been commonly used in food applications that require blocking various gases such as water vapor and oxygen. In particular, those formed with a thin inorganic oxide film such as silicon oxide, aluminum oxide, or a mixture thereof are widely used because they are transparent and allow the contents to be confirmed.

[0004] However, the above-mentioned gas barrier laminate film may be locally heated during the formation process, causing damage to the substrate, or defects or pinholes may occur in the inorganic thin film layer due to decomposition or degassing of the low-molecular-weight portion or additives such as plasticizers, resulting in a decrease in gas barrier properties. Furthermore, during post-processing of the packaging material, such as printing, lamination, and bag making, the inorganic thin film layer may crack, causing a decrease in gas barrier properties. In particular, if the inorganic thin film layer is damaged during the above-mentioned process, the gas barrier properties may be significantly reduced by subsequent retort treatment, and the interlayer adhesive strength between the inorganic thin film and the resin in contact with it may be reduced, resulting in leakage of the contents.

[0005] As a method for improving the deterioration of a gas barrier laminate film having an inorganic thin film formed thereon, a method is known in which a coating layer made of various aqueous polyurethane resins, polyester resins, or a mixture of polyurethane and polyester is provided between a polyester base film and an inorganic thin film layer formed, for example, by a vapor deposition method (for example, Patent Document 1).

[0006] In addition to the gas barrier laminate film, many gas barrier films have been proposed in which a resin composition is coated on a substrate film. In particular, coating agents using polyvinyl alcohol or ethylene-vinyl alcohol copolymers, which themselves have high oxygen barrier properties, have been put to practical use.

[0007] Furthermore, gas barrier films have been proposed in which a plastic substrate film is coated with a gas barrier layer formed by blending the vinyl alcohol resin with an inorganic layered compound such as montmorillonite. Examples include a case in which a gas barrier layer composed of polyvinyl alcohol, a crosslinking agent, and an inorganic layered compound is provided on a substrate film, and a case in which a gas barrier layer composed of an ethylene-vinyl alcohol copolymer, a water-soluble zirconium crosslinking agent, and an inorganic layered compound is provided on a substrate film (see, for example, Patent Documents 2 and 3). Because these gas barrier films use crosslinked resins, they are moisture-resistant and can withstand water resistance to a boiling point. However, when used for retort packaging, the gas barrier properties and laminate strength after retort processing at a pressurized temperature of 120 to 130°C are not fully satisfactory. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2-50837 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-349769 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-297527 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention was made in response to the problems of the conventional technology, and its object is to provide a laminated film that has excellent oxygen and water vapor barrier properties even after retort treatment and has adhesion that prevents delamination after retort treatment. [Means for solving the problem]

[0010] The present inventors have discovered that by designing a specific laminate film that meets the required performance, it is possible to provide a film that maintains good gas barrier properties and adhesiveness even when subjected to retort treatment, and have thereby completed the present invention.

[0011] That is, the present invention comprises the following configurations. 1. A laminated film in which a surface layer (C), a base layer (A), and a surface layer (B) are laminated in this order on the surface layer (B) of a base film, and an anchor coat layer and an inorganic thin film layer are laminated in this order with or without other layers interposed therebetween, wherein the surface layer (B) is made of a resin composition containing two or more types of resins, and the coating amount of the anchor coat layer is 0.50 g / m 2 and the moisture content of the laminated film is 0.2% by mass or less. 2. The laminated film according to 1., wherein the anchor coat layer contains at least one of polyester resin and polyurethane resin. 3. The laminate film according to either 1. or 2., wherein the inorganic thin film layer is made of a metal oxide. 4. The laminate film or laminate film according to any one of 1. to 3., wherein the base layer (A) is made of a resin containing polyolefin as a main component. 5. A laminate comprising the laminate film according to any one of 1. to 4. above and an olefin-based sealant layer laminated on the surface opposite to the surface layer (C). 6. The laminate according to 5., characterized in that the laminate has a lamination strength of 2.0 N / 15 mm or more. 7. The laminate according to 5. or 6., characterized in that, when the oxygen permeability value of the laminate measured under conditions of 23°C x 65% RH is (A) and the oxygen permeability value of the laminate measured under conditions of 23°C x 65% RH after performing retort treatment in which the laminate is kept in pressurized hot water at a temperature of 130°C for 30 minutes is (B), the barrier value deterioration rate after moist heat treatment, expressed by the following formula, is 150% or less. Barrier value deterioration rate after heat and moisture treatment (%) = (B / A) × 100 Formula (1) 8. A packaging material comprising at least one layer of the laminate film according to any one of 1. to 4. above or the laminate according to 5. to 7. above. [Effects of the Invention]

[0012] By using this technique, the present inventors have been able to provide a laminate that retains the necessary properties, such as barrier properties and adhesive properties, required for packaging materials even after retort treatment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. A laminated film in which a surface layer (C), a substrate layer (A), and a surface layer (B) are laminated in this order on the surface layer (B) of a substrate film, and an anchor coat layer and an inorganic thin film layer are laminated in this order with or without other layers interposed therebetween, wherein the surface layer (B) is made of a resin composition containing two or more resins, and the coating amount of the anchor coat layer is 0.50 g / m 2 and the moisture content of the laminated film is 0.2 mass % or less. Each layer of the laminate will now be described.

[0014] [Base film layer] (1) Base material layer (A) The base layer of the present invention preferably contains a polyolefin such as polypropylene or polyethylene resin as the main component, in order to maintain the moisture content of the laminate film at 0.20% by mass or less. The term "main component" means that the proportion of a specific component in the total components is 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The polypropylene used in the layer may also be polypropylene copolymerized with 0.5 mol% or less of ethylene and / or an α-olefin having 4 or more carbon atoms. Such copolymerized polypropylenes are also included in the polypropylene of the present invention (hereinafter referred to as "polypropylene"). The copolymerization component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and completely homopolypropylene containing no copolymerization component is most preferred. When ethylene and / or an α-olefin having 4 or more carbon atoms is copolymerized in an amount exceeding 0.5 mol %, the crystallinity and rigidity may be reduced too much, resulting in a large heat shrinkage rate at high temperatures. Such resins may be blended and used.

[0015] The mesopentad fraction ([mmmm]%) measured by C-NMR, which is an index of the stereoregularity of the polypropylene constituting the base layer (A) of the laminated film of the present invention, is preferably 98 to 99.5%, more preferably 98.1% or more, and even more preferably 98.2% or more. If the mesopentad fraction of polypropylene is low, the elastic modulus may be low and the heat resistance may be insufficient. 99.5% is the practical upper limit.

[0016] The mass average molecular weight (Mw) of the polypropylene constituting the base layer (A) of the laminated film of the present invention is preferably 180,000 to 500,000. If the Mw is less than 180,000, the melt viscosity is low, resulting in instability during casting and poor film-forming properties.If the Mw is more than 500,000, the amount of components with a molecular weight of 100,000 or less will be 35% by mass, resulting in poor heat resistance. A more preferred lower limit of Mw is 190,000, even more preferably 200,000, and a more preferred upper limit of Mw is 320,000, even more preferably 300,000, and particularly preferably 250,000.

[0017] The number average molecular weight (Mn) of the polypropylene constituting the base layer (A) of the laminated film of the present invention is preferably 20,000 to 200,000. If it is less than 20,000, the melt viscosity will be low, resulting in instability during casting and poor film-forming properties, whereas if it exceeds 200,000, heat resistance will be poor. A more preferred lower limit of Mn is 30,000, even more preferably 40,000, and particularly preferably 50,000, and a more preferred upper limit of Mn is 80,000, even more preferably 70,000, and particularly preferably 60,000.

[0018] Furthermore, the Mw / Mn, which is an index of molecular weight distribution, of the polypropylene constituting the base layer (A) is preferably 2.8 to 10, more preferably 2.8 to 8, even more preferably 2.8 to 6, and particularly preferably 2.8 to 5.4. The lower limit is preferably 3 or more, and more preferably 3.3 or more. The molecular weight distribution of polypropylene can be adjusted by polymerizing components of different molecular weights in multiple stages in a series of plants, blending components of different molecular weights offline in a kneader, blending catalysts with different performances and polymerizing them, or using a catalyst that can achieve the desired molecular weight distribution.

[0019] When the polypropylene constituting the base layer (A) of the laminated film of the present invention has an Mw / Mn in the range of 2.8 to 5.4, it preferably has a melt flow rate (MFR; 230°C, 2.16 kgf) of 2 g / 10 min to 20 g / 10 min. The lower limit of the MFR of the polypropylene constituting the base layer (A) is more preferably 3 g / 10 min, even more preferably 4 g / 10 min, and particularly preferably 5 g / 10 min. The upper limit of the MFR of the polypropylene constituting the base layer (A) is more preferably 15 g / 10 min, even more preferably 12 g / 10 min. When the Mw / Mn and MFR of the polypropylene constituting the base layer (A) are within this range, the polypropylene can withstand hot water treatment, and also has good adhesion to a chill roll and excellent film formability.

[0020] (2) Surface layer (B) The surface layer (B) of the present invention preferably contains a polyolefin such as polypropylene or polyethylene resin as the main component, in order to keep the moisture content in the laminated film at 0.20% by mass or less. The term "main component" means that the proportion of a specific component in all components is 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Hereinafter, polypropylene will be used as an example for explanation. The polypropylene resin composition constituting the surface layer (B) of the laminate film of the present invention is preferably a resin composition containing two or more resins and has an MFR of 1.0 g / 10 min to 10.0 g / 10 min. The lower limit of the MFR of the polypropylene resin composition constituting the surface layer (B) is more preferably 2.0 g / 10 min, even more preferably 3.0 g / 10 min, and particularly preferably 4.0 g / 10 min. The upper limit of the MFR of the polypropylene resin composition constituting the surface layer (B) is more preferably 9.0 g / 10 min, even more preferably 8.0 g / 10 min, and particularly preferably 5.5 g / 10 min. Within this range, the film formability is good and the appearance is excellent. If the MFR of the polypropylene resin composition constituting the surface layer (B) is less than 1.0 g / 10 min, when the MFR of the polypropylene constituting the base layer (A) is high, the viscosity difference between the base layer (A) and the surface layer (B) becomes large, making unevenness (unevenness in the raw web) more likely to occur during film formation. If the MFR of the polypropylene resin composition constituting the surface layer (B) exceeds 10 g / 10 min, the adhesion to the cooling roll will be poor, air will be entrapped, the smoothness will be poor, and there is a risk that defects will occur as a result.

[0021] For polypropylene-based resins with a smaller MFR, polypropylenes copolymerized with ethylene and / or α-olefins with four or more carbon atoms can also be used. Examples of α-olefins with four or more carbon atoms include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Polar copolymers such as maleic acid can also be used as other copolymerization components. The total amount of ethylene and / or α-olefins having 4 or more carbon atoms and other copolymerization components is preferably 8.0 mol% or less. If copolymerized in an amount exceeding 8.0 mol%, the film may whiten, resulting in poor appearance, or may become sticky, making film formation difficult.

[0022] Furthermore, although the individual resins to be blended may be copolymerized in an amount exceeding 8.0 mol %, it is preferable that the blend contains, on a monomer unit basis, 8.0 mol % or less of monomers other than propylene. As the polypropylene resin having a larger MFR, the above copolymer polypropylene or a homopolypropylene resin can be used.

[0023] The polypropylene resin composition constituting the surface layer (B) of the laminated film of the present invention is preferably a mixture of resin compositions with different crystallinity. By mixing polypropylene resin compositions with different crystallinity, the crystallinity can be partially changed on the film surface, and the surface roughness of the film can be controlled. In addition, the surface hardness can be controlled within a desired range. It is believed that these effects enable the film to maintain adhesion even after boiling or retort treatment.

[0024] The antiblocking agent can be appropriately selected from inorganic particles such as silica, calcium carbonate, kaolin, and zeolite, and organic particles such as acrylic, polymethacrylic, and polystyrene particles. Among these, silica and polymethacrylic particles are particularly preferred. The average particle size of the antiblocking agent is preferably 1.0 to 3.0 μm, and more preferably 1.0 to 2.7 μm. The average particle size is measured by taking a photograph using a scanning electron microscope, measuring the Feret's diameter in the horizontal direction using an image analyzer, and expressing the average value. There are no particular restrictions on the amount of antiblocking agent added, as long as the amount added to the surface layers (B) and (C) is adjusted so that the haze, dynamic friction coefficient, center surface average roughness (SRa), and air release time fall within the specified ranges.

[0025] The surface wetting tension of the surface layer (B) of the laminated film of the present invention is preferably 38 mN / m or more. Wetting tension represents the surface tension (mN / m) of a mixed solution reagent determined to wet the film surface, and is related to the wettability of printing inks and adhesives. A wetting tension of 38 mN / m or more improves adhesion to vapor-deposited films, coating films, and adhesives used for laminating with other film components. To achieve a wetting tension of 38 mN / m or more, additives such as antistatic agents and surfactants are usually used. However, these methods have the effect of reducing surface resistance, so physicochemical surface treatments such as corona treatment and heat treatment are preferred. For example, in the corona treatment, it is preferable to use a preheating roll and a treatment roll and to carry out discharge in the air.

[0026] (3) Surface layer (C) The laminated film of the present invention may have a surface layer (C) on the surface of the base layer (A) opposite to the surface layer (B). The surface layer (C) of the present invention preferably contains a polyolefin such as polypropylene or polyethylene resin as the main component, in order to keep the moisture content of the laminated film at 0.20% by mass or less. The term "main component" means that a specific component accounts for 50% by mass or more of the total components, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The polypropylene used in the layer may also be polypropylene copolymerized with 0.5 mol% or less of ethylene and / or an α-olefin having 4 or more carbon atoms. Such copolymerized polypropylenes are also included in the polypropylene of the present invention (hereinafter referred to as polypropylene). The copolymerization component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and completely homopolypropylene containing no copolymerization component is most preferred. When ethylene and / or an α-olefin having 4 or more carbon atoms is copolymerized in an amount exceeding 0.5 mol %, the crystallinity and rigidity may be reduced too much, resulting in a large heat shrinkage rate at high temperatures. Such resins may be blended and used.

[0027] The surface layer (C) preferably has a surface centerline average roughness (SRa) of 0.020 μm or more as measured with a three-dimensional profilometer. The surface centerline average roughness (SRa) of the surface layer (C) is more preferably 0.022 μm or more, even more preferably 0.025 μm or more, and particularly preferably 0.028 μm or more. If the surface centerline average roughness (SRa) of the surface layer (C) is less than 0.020 μm, the surface irregularities are small, resulting in poor film slippage, poor film-to-film air release time, and poor blocking resistance. There are several methods for keeping the surface centerline average roughness (SRa) of the surface layer (C) within the specified range, and it can be adjusted by the average particle size and amount of antiblocking agent added. The surface of the surface layer (C) of the laminate of the present invention preferably has a center surface average roughness (SRa) of 0.040 μm or less as measured by a three-dimensional roughness meter.

[0028] The polypropylene resin used in the present invention is obtained by polymerizing the raw material propylene using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among these, it is preferable to use a Ziegler-Natta catalyst, which is capable of polymerization with high stereoregularity, in order to eliminate heterogeneous bonds. The raw material propylene may be polymerized by any known method, such as a method of polymerizing in an inert solvent such as hexane, heptane, toluene, or xylene, a method of polymerizing in a liquid monomer, a method of adding a catalyst to a gaseous monomer and polymerizing in a gas phase, or a method of polymerizing using a combination of these methods.

[0029] The base layer (A) and / or surface layer (B) and / or surface layer (C) of the laminated film of the present invention may contain additives or other resins. Examples of additives include antioxidants, UV absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, inorganic or organic fillers, etc. Other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers of propylene with ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers. These may be sequentially polymerized using a multi-stage reactor, blended with polypropylene resin using a Henschel mixer, pre-prepared master pellets prepared using a melt kneader and diluted with polypropylene to a predetermined concentration, or the entire amount may be melt-kneaded and used. Furthermore, corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, and known anchor coating, printing, decoration, etc. may be applied as long as they do not impair the objectives of the present invention.

[0030] The method for producing the substrate film of the present invention is preferably a biaxially oriented film, and can be obtained by melt-extruding the polypropylene resin composition constituting the substrate layer (A), the polypropylene resin composition constituting the surface layer (B), and the polypropylene resin composition constituting the surface layer (C) using separate extruders, co-extruding them through a die, and cooling them with a cooling roll to form an unstretched sheet, stretching the unstretched sheet in the machine direction (MD) and the transverse direction (TD), and then heat-setting the sheet. The melt extrusion temperature is preferably about 200 to 280°C. To obtain a laminate with good appearance without disturbing the layers within this temperature range, it is preferable that the viscosity difference (MFR difference) between the polypropylene raw material for the base layer (A) and the polypropylene raw material for the surface layer (B) is 6.0 g / 10 min or less. If the viscosity difference is more than 6 g / 10 min, the layers are likely to be disturbed, resulting in a poor appearance. The viscosity difference is more preferably 5.5 g / 10 min or less, and even more preferably 5.0 g / 10 min or less. The surface temperature of the cooling roll is preferably 25 to 35°C, and more preferably 27 to 33°C.

[0031] The lower limit of the stretching ratio in the machine direction (MD) is preferably 3 times, more preferably 3.5 times. If it is less than this, film thickness unevenness may occur. The upper limit of the MD stretching ratio is preferably 8 times, more preferably 7 times. If it exceeds this, subsequent TD stretching may become difficult. The lower limit of the MD stretching temperature is preferably 120°C, more preferably 125°C, and even more preferably 130°C. If it is less than this, mechanical load may increase, thickness unevenness may increase, and surface roughness of the film may occur. The upper limit of the MD stretching temperature is preferably 160°C, more preferably 155°C, and even more preferably 150°C. A higher temperature is preferable because it reduces dimensional change during moist heat treatment and reduces deterioration of barrier properties and adhesion, but it may cause adhesion to the roll, making stretching impossible, or cause surface roughness.

[0032] The lower limit of the stretching ratio in the transverse direction (TD) is preferably 4 times, more preferably 5 times, and even more preferably 6 times. If the stretching ratio is less than the above range, thickness unevenness may occur. The upper limit of the TD stretching ratio is preferably 20 times, more preferably 17 times, even more preferably 15 times, and particularly preferably 12 times. If the stretching ratio exceeds the above range, the heat shrinkage may become high and the film may break during stretching. The preheating temperature for TD stretching is preferably set 5 to 15°C higher than the stretching temperature in order to quickly raise the film temperature to near the stretching temperature. The lower limit of the TD stretching temperature is preferably 150°C, more preferably 155°C, even more preferably 158°C, and particularly preferably 160°C. If the stretching temperature is less than the above range, the film may not soften sufficiently and break, or the dimensional change may be large during wet heat treatment, resulting in deterioration of barrier properties and adhesion. The upper limit of the TD stretching temperature is preferably 170°C, more preferably 168°C, and even more preferably 165°C. A higher temperature is preferred to reduce dimensional changes, but if the temperature exceeds the above range, the low molecular weight components will melt and recrystallize, resulting in a decrease in orientation and possibly causing surface roughness and whitening of the film.

[0033] The stretched film is heat-set. The lower limit of the heat-setting temperature is preferably 163°C, more preferably 165°C. If the temperature is lower than the above, dimensional change during wet heat treatment is large, which may result in deterioration of barrier properties and adhesion. Furthermore, prolonged treatment may be required to reduce dimensional change, which may result in poor productivity. The upper limit of the heat-setting temperature is preferably 176°C, more preferably 175°C. If the temperature exceeds the above range, low-molecular-weight components may melt and recrystallize, causing surface roughness and whitening of the film.

[0034] It is preferable to relax the film during heat setting. The lower limit of the relaxation rate is preferably 2%, more preferably 3%. If it is less than this, the dimensional change during moist heat treatment is large, and the barrier properties and adhesion may deteriorate. The upper limit of the relaxation rate is preferably 10%, more preferably 8%. If it exceeds this, thickness unevenness may increase.

[0035] Furthermore, in order to reduce dimensional changes, the film produced by the above process can be wound into a roll and then annealed offline.

[0036] The biaxially oriented polypropylene laminate thus obtained may be subjected to corona discharge, plasma treatment, flame treatment, etc., as required, and then wound up with a winder to obtain the biaxially oriented polypropylene film roll of the present invention.

[0037] [Anchor coat layer] In the present invention, an anchor coat layer is provided on the surface layer (B). The presence of the anchor coat layer can suppress the exposure of oligomers and antiblocking agents from the polypropylene resin. Furthermore, it can also enhance interlayer adhesion when laminating other layers on the anchor coat layer. In particular, the formation of an inorganic thin film layer not only requires adhesion, but also can be problematic due to the inability to form a thin film on protruding portions caused by surface irregularities, resulting in poor barrier properties. Furthermore, using a gas-barrier material for the anchor coat layer itself can significantly improve the gas barrier performance of the laminate. Furthermore, laminating a water-resistant anchor coat layer prevents the penetration of hot water, thereby reducing barrier and adhesion defects after boiling or retort treatment. Because the anchor coat layer incorporates a resin component containing polar groups to ensure the necessary adhesion, it is often composed of a material with a high moisture content. The inventors have newly discovered that the aforementioned defects after wet heat treatment can be improved by controlling the moisture content of the entire laminate film to a predetermined level. To control the moisture content of the laminated film within the preferred range described below, it is necessary to employ a composition and / or processing conditions that will exhibit adhesion and barrier properties in the anchor coat layer with a small adhesion amount described below.

[0038] In the present invention, the adhesion amount of the anchor coat layer is 0.01 to 0.50 g / m 2 This allows the anchor coat layer to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. The amount of the anchor coat layer is preferably 0.05 g / m 2 More preferably, 0.10 g / m 2 or more, and preferably 0.47 g / m 2 or less, more preferably 0.45 g / m 2 The adhesion weight of the anchor coat layer is 0.50 g / m or less. 2If the thickness of the protective layer exceeds 0.01 g / m, the gas barrier property improves, but the moisture content in the laminated film increases due to the thick film thickness. In terms of processability, the thick film thickness may cause blocking. Furthermore, there is a concern that it may have a negative impact on the recyclability and manufacturing costs of the film. On the other hand, if the thickness of the protective layer is 0.01 g / m, 2 If it is less than this, there is a risk that sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0039] The resin composition used in the anchor coat layer of the present invention may be a resin such as a urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, or polybutadiene-based resin to which an epoxy-based, isocyanate-based, or melamine-based curing agent has been added. It may further contain a silicon-based crosslinking agent, an oxazoline compound, a carbodiimide compound, or an epoxy compound. In particular, the inclusion of a urethane resin is preferred because, in addition to the barrier performance due to the high cohesiveness of the urethane bond itself, the polar groups interact with the inorganic thin film layer, and the presence of amorphous portions provides flexibility, thereby reducing damage even when subjected to stress due to moist heat treatment. Polyester resins are also preferred because they are expected to have the same effect. In the present invention, it is preferable to include a polyurethane containing polyester and isocyanate as constituent components, and it is even more preferable to add a silicon-based crosslinking agent from the viewpoint of improving water-resistant adhesion.

[0040] (1) Urethane resin From the viewpoint of improving barrier properties through cohesion, the urethane resin used in the present invention preferably has a glass transition temperature (Tg) of 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher. However, in order to develop adhesive strength, a soft resin with excellent flexibility and a Tg of 100°C or lower may be mixed in. In this case, the addition ratio of the soft resin is preferably within the range of 0 to 80%, more preferably within the range of 10 to 70%, and even more preferably within the range of 20 to 60%. When the addition ratio is within the above range, cohesion and flexibility can be achieved at the same time, resulting in good barrier properties and adhesiveness. However, if the addition ratio exceeds 80%, the film may become too soft, which may lead to a decrease in barrier performance.

[0041] From the viewpoint of improving gas barrier properties, it is more preferable to use a urethane resin containing an aromatic or araliphatic diisocyanate component as a main constituent component. Among these, it is particularly preferable to contain a metaxylylene diisocyanate component. By using the above 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 properties.

[0042] In the present invention, the proportion of aromatic or araliphatic diisocyanate in the urethane resin is preferably 50 mol % or more (50 to 100 mol %) relative to 100 mol % of the polyisocyanate component (F). 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 properties may not be obtained.

[0043] (2) Silicon-based crosslinking agents The urethane resin used in the present invention may be blended with various crosslinking agents to improve the cohesive strength and moist heat resistance of the film, as long as the gas barrier properties are not impaired. Examples of crosslinking agents include silicon-based crosslinking agents, oxazoline compounds, carbodiimide compounds, epoxy compounds, etc. Among these, silicon-based crosslinking agents are particularly preferred, as they can improve the water-resistant adhesion, particularly with inorganic thin film layers, by blending silicon-based crosslinking agents. Other crosslinking agents may be used in combination with oxazoline compounds, carbodiimide compounds, epoxy compounds, etc.

[0044] As the silicon-based crosslinking agent, from the viewpoint of crosslinking inorganic matter and organic matter, silane coupling agent is preferred.As the silane coupling agent, hydrolyzable alkoxysilane compound, for example, halogen-containing alkoxysilane (chloro C2-4 alkyl tri C1-4 alkoxysilane such as 2-chloroethyl trimethoxysilane, 2-chloroethyl triethoxysilane, 3-chloropropyl trimethoxysilane, 3-chloropropyl triethoxysilane, etc.), alkoxysilane having epoxy group [2-glycidyloxyethyl trimethoxysilane, 2-glycidyloxyethyl triethoxysilane, 3-glycidyloxypropyl triethoxysilane, etc.] trimethoxysilane, glycidyloxy C2-4 alkyltriC1-4 alkoxysilanes such as 3-glycidyloxypropyltriethoxysilane, glycidyloxydiC2-4 alkyldiC1-4 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-aminoC2-4 alkyl)aminoC2-4 alkyltriC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, and 3-[N-(2-aminoethyl)amino]propyltriethoxysilane; (aminoC2-4 alkyl)aminodiC2-4 alkyldiC1-4 alkoxysilanes such as 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane and 3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane;Alkoxysilanes with mercapto groups (mercapto C2-4 alkyltri C1-4 alkoxysilanes such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc.; mercapto di C2-4 alkyldi C1-4 alkoxysilanes such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc.), alkoxysilanes with vinyl groups (vinyltri C1-4 alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, etc.), ethylene Examples include alkoxysilanes having a hydrophilically 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]. These silane coupling agents can be used alone or in combination. Of these silane coupling agents, silane coupling agents having an amino group are preferred.

[0045] 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 a silane coupling 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 3.00% 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.

[0046] (3) Polyester resin The polyester resin used in the present invention is produced by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. The molecular weight of the polyester 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 it 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.

[0047] The Tg of the polyester used in the present invention is preferably 15°C or higher. If the temperature is lower than this, the resin will become tacky after the coating operation, making it more susceptible to blocking and making the winding operation after coating difficult. If the Tg is 15°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 18°C ​​or higher, and even more preferably 25°C or higher.

[0048] The polyester used in the present invention is prepared by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component. [Polycarboxylic acid component] The polycarboxylic acid component of the polyester 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 resins. A uniformly coated protective layer reduces variation in barrier performance, ultimately 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 resins due to wet heat treatment and suppressing oligomer formation. Examples of aromatic polycarboxylic acids or their anhydrides in which carboxylic acids are 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.

[0049] 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.

[0050] [Polyhydric alcohol component] The polyhydric alcohol component of the polyester used in the present invention is not particularly limited as long as it can synthesize a polyester that exhibits gas barrier replenishing 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.

[0051] In the present invention, it is preferable to use the polyhydric alcohol component described above, but other polyhydric alcohol components may also be copolymerized as long as the effects of the present invention are not impaired. 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 properties.

[0052] 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, while if it exceeds 1,000 ppm, problems such as inhibition of the urethanization reaction may occur when an isocyanate curing agent is used.

[0053] (4) Isocyanate-based curing agent In the present invention, when a polyester resin is used as the main component of the coating agent constituting the anchor coat layer, it is preferable to use an isocyanate-based curing agent to form a urethane resin. In this case, the coating layer becomes crosslinked, which has the advantage of improving heat resistance, abrasion resistance, and rigidity. Therefore, it is easy to use in boiling and retort packaging. On the other hand, there are problems with the liquid not being reusable after mixing with the curing agent, and a curing (aging) process is required after coating. Examples of advantages include the fact that, as a simple overcoat varnish, there is no risk of thickening of the coating liquid, making coating production easy to manage, the coating liquid can be diluted and reused, and the 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 in the coating layer is linear, which may result in insufficient heat resistance or abrasion resistance, or problems with use in boiling and retort packaging.

[0054] 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. However, 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 application.

[0055] 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 enhancing the gas barrier function. Furthermore, when the resin of the coating material is a linear resin, crosslinking with a trivalent or higher polyisocyanate can impart heat resistance and abrasion resistance. The polyisocyanate compound 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, and norbornane diisocyanate, as well as 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.

[0056] The method for applying the resin composition for the anchor coat layer 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.

[0057] When forming the anchor coat layer, it is preferable to apply the resin composition for the anchor coat layer and then heat-dry it. The drying temperature is preferably 90 to 180°C, more preferably 100 to 170°C, and even more preferably 110 to 160°C. Drying temperatures below 90°C can result in insufficient drying of the anchor coat layer, or film formation of the anchor coat layer can be hindered, resulting in reduced cohesive strength and water-resistant adhesion, and consequently reduced barrier properties and hand-tearability. On the other hand, drying temperatures above 180°C can result in excessive heat being applied to the film, making it brittle and reducing puncture strength, or shrinking and reducing processability. In particular, drying at temperatures above 100°C, preferably above 110°C, can effectively promote film formation of the anchor coat layer and improve water-resistant adhesion. In addition to drying, additional heat treatment at temperatures as low as possible can also be effective in promoting film formation of the anchor coat layer.

[0058] Furthermore, by applying an additional heat treatment in a low-temperature range, the moisture content in the laminated film can be controlled to a predetermined level. The preferred temperature conditions for the heat treatment are 25°C to 80°C, more preferably 30°C to 70°C, and even more preferably 35°C to 60°C. If the heat treatment temperature is 20°C or lower, the heat treatment effect is small, making it difficult to control the moisture content. On the other hand, if the heat treatment temperature exceeds 80°C, the laminated film will be subjected to too much heat, causing poor appearance such as wrinkles. Furthermore, the preferred heat treatment time varies depending on the amount of anchor coat layer attached and the temperature, but when treated at 40°C, for example, it is preferably 24 hours or more, more preferably 48 hours or more, and even more preferably 72 hours or more.

[0059] In the laminate film of the present invention, the ratio (P1 / P2) of the peak intensity (P1) having an absorption maximum in the 1250±50 cm-1 region to the peak intensity (P2) having an absorption maximum in the 1070±10 cm-1 region in the total reflection infrared absorption spectrum of the anchor coat layer is preferably in the range of 1.0 to 10.0. It is preferably in the range of 1.2 to 9.0, and more preferably in the range of 1.5 to 8.0. The peak at 1250±50 cm-1 is a peak derived from a COC structure derived from an aromatic or unsaturated aliphatic skeleton and serves as an indicator of the degree of crosslinking of the polyester or polyurethane skeleton. Furthermore, the peak at 1070±10 cm-1 is a peak derived from C-OH and serves as an indicator of the amount of hydroxyl groups derived from the polyester or polyurethane skeleton in the anchor coat layer. (P1 / P2) represents the ratio of hydroxyl groups in the polyester or polyurethane backbone. By maintaining this ratio within the above range, the film becomes highly polarized while maintaining the desired water content, enhancing the adhesion between the anchor coat layer and the inorganic thin film layer. As a result, gas barrier performance and adhesion are maximized even after wet heat treatment. If (P1 / P2) is less than 1.0, the anchor coat layer contains a large amount of hydroxyl groups, strengthening the bond with the inorganic thin film layer. However, crosslinking within the anchor coat layer may not progress, resulting in reduced film-forming properties and brittleness. Alternatively, if the anchor coat layer contains a large number of polar groups remaining, the water content may increase. On the other hand, if (P1 / P2) exceeds 10.0, the anchor coat layer contains a small amount of hydroxyl groups, resulting in a sparse inorganic thin film layer, making it difficult to achieve gas barrier properties and adhesion. To achieve the (P1 / P2) value of the anchor coat layer within the specified range, it is necessary to use the materials described above to achieve the desired coating amount, and furthermore, to maintain the material ratio within the appropriate range and combine it with the drying and heat treatment conditions described above.

[0060] [Inorganic thin film layer] The laminate of the present invention has an inorganic thin film layer. The inorganic thin film layer is preferably a metal oxide layer. There are no particular limitations on the material forming the metal oxide layer as long as it can be formed into a thin film. However, from the viewpoint of gas barrier properties, inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and a mixture of silicon oxide and aluminum oxide are preferred. In this composite 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 metal oxide layer tends to become hard, and the film may be destroyed after wet heat treatment, resulting in a decrease in gas barrier properties. Furthermore, if the Al concentration is 100 mass%, the water vapor barrier performance is good, but the surface tends to be smooth due to the use of a single material, which makes the surface less slippery and more susceptible to processing defects (wrinkles, acne, etc.). The silicon oxide referred to here is a variety of silicon oxides such as SiO and SiO2, or a mixture thereof, and the aluminum oxide is a variety of aluminum oxides such as AlO and Al2O3, or a mixture thereof.

[0061] The mixture ratio of silicon oxide to aluminum oxide in this mixture can be determined using a monitor that measures composition using fluorescent X-rays. The object being measured is irradiated with X-rays, the intensity of the characteristic X-rays emitted from the atoms contained in the object is measured, and the value is converted into composition and output. The conversion is done by measuring an object of known film thickness and composition and creating a calibration curve in relation to the obtained fluorescent X-rays. When the plastic substrate film contains the same atoms as those contained in the inorganic thin film layer, for example, when the inorganic thin film layer contains SiOx, and when the plastic film contains silica powder as a lubricant, and Si atoms are contained in common, a film is prepared in advance by forming inorganic thin film layers of different known thicknesses on plastic substrate films containing the same concentration of the atoms, and then the film is measured with the monitor.The thickness of the unknown inorganic thin film layer can be obtained by calculating the relationship between the obtained fluorescent X-ray intensity and the film thickness and creating a calibration curve.

[0062] The inorganic thin film layer has a thickness of usually 1 to 100 nm, preferably 5 to 50 nm. If the thickness of the inorganic thin film layer 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 greater than 100 nm, the corresponding improvement in gas barrier properties cannot be obtained and is actually disadvantageous in terms of flex resistance and production costs.

[0063] The method for forming the inorganic thin film layer is not particularly limited. Known deposition methods, such as physical vapor deposition (PVD) methods (e.g., vacuum deposition, sputtering, ion plating), or chemical vapor deposition (CVD), may be appropriately employed. A typical method for forming an inorganic thin film layer will be described below, taking silicon oxide / aluminum oxide-based thin films as an example. For example, when using vacuum deposition, a mixture of SiO2 and Al2O3 or a mixture of SiO2 and Al is preferably used as the deposition source. These deposition sources 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 7 mm. Heating methods include resistance heating, high-frequency induction heating, electron beam heating, and laser heating. Reactive deposition can also be employed, using reactive gases such as oxygen, nitrogen, hydrogen, argon, carbon dioxide, and water vapor, or by adding ozone or ion-assisted deposition. Furthermore, the deposition conditions can be freely changed by applying a bias to the deposition target (the laminate to be deposited) or by heating or cooling the deposition target. The deposition material, reactive gas, bias of the deposition target, heating / cooling, etc. can be changed in the same way when the sputtering method or the CVD method is adopted.

[0064] [Laminated film] The moisture content of the laminated film of the present invention is preferably 0.20% by mass or less, more preferably 0.18% by mass or less, even more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less. The preferred lower limit is 0.01% by mass or more. If the moisture content is greater than 0.20% by mass, there is a tendency for moisture penetration during moist heat treatment to be significant, causing the inorganic thin film to crack and resulting in reduced gas barrier properties and adhesion. The moisture content here is measured using a heat-drying moisture meter. The detailed measurement method is as described in the Examples, but in short, the moisture content is calculated using the formula (amount of moisture [g] released from the sample) / (sample weight [g]).

[0065] [Protective layer] In the present invention, a protective layer can be provided on the inorganic thin film layer when additional gas barrier performance or processing such as printing is required. The inorganic thin film layer is not a completely dense film, but has minute defects scattered throughout. By forming a protective layer by coating the inorganic thin film layer with a specific resin composition for the protective layer (described below), the resin in the resin composition for the protective layer penetrates into the defects in the inorganic thin film layer, resulting in stable gas barrier properties. Additionally, using a material with gas barrier properties for the protective layer itself significantly improves the gas barrier performance of the laminate. However, it should be noted that providing a protective layer increases costs due to the additional steps and may also have an environmental impact depending on the materials used. It should also be noted that the protective layer may change physical properties such as surface roughness.

[0066] [Laminate] The laminate of the present invention uses a heat-sealable resin called a sealant. The heat-sealable resin layer is usually provided on the anchor coat layer or inorganic thin film layer side, but may also be provided on the outer side of the resin film layer (the side opposite the inorganic thin film-formed surface). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. The thermoplastic polymer forming the heat-sealable resin layer may be any polymer capable of sufficiently exhibiting sealant adhesion, including olefin-based polyethylene resins such as HDPE, LDPE, and LLDPE, polypropylene resins, ethylene-vinyl acetate copolymers, ethylene-α-olefin random copolymers, and ionomer resins. Among these, LLDPE or polypropylene resins are particularly preferred due to their versatility in terms of durability, seal strength, cost, and mono-materialization. The thickness of the sealant layer is preferably 20 to 100 μm, more preferably 30 to 90 μm, and even more preferably 40 to 80 μm. A thickness less than 20 μm may result in insufficient seal strength or may be difficult to handle due to lack of stiffness. On the other hand, if the thickness exceeds 100 μm, the bag will be stiff and difficult to handle, and the price may also become high.

[0067] The total thickness of the laminate of the present invention is preferably 9 μm or more and 200 μm or less, more preferably 10 μm or more and 170 μm or less, even more preferably 12 μm or more and 150 μm or less, and particularly preferably 15 μm or more and 120 μm or less.

[0068] The haze of the laminate of the present invention is preferably 5% or less, more preferably 0.2% to 5.0%, even more preferably 0.3% to 4.5%, and particularly preferably 0.4% to 4.0%. A haze within the above range may facilitate use in applications requiring transparency. The haze tends to worsen, for example, when the stretching temperature or heat setting temperature is too high, the cooling roll temperature is high and the cooling rate of the unstretched (raw) sheet is slow, or the amount of low-molecular-weight components is too high. By adjusting these factors, the haze can be kept within the above range.

[0069] The laminate of the present invention has an oxygen permeability of 25 cc / m under conditions of 23°C x 65% RH. 2 / d / atm or less, and more preferably 20cc / m 2 / d / atm or less, more preferably 15cc / m 2 The preferred lower limit of oxygen permeability is 0.1 cc / m 2 / d / atm or more. In addition, the water vapor permeability under the conditions of 40℃ × 90% RH is 3.0 g / m 2 / d or less, and more preferably 2.5 g / m 2 / d or less, more preferably 2.0 g / m 2 / d or less. The preferred lower limit of the water vapor permeability is 0.1 g / m 2 / d or more. Furthermore, the barrier value deterioration rate of the laminate of the present invention after wet heat treatment, represented by formula (1), is preferably 150% or less, more preferably 140% or less, and even more preferably 130% or less.

[0070] The laminate of the present invention preferably has a laminate strength of 2.0 N / 15 mm or more under conditions of 23°C x 65% RH, in both the dry and wet evaluations described below, more preferably 2.3 N / 15 mm or more, and even more preferably 2.6 N / 15 mm or more. If the laminate strength is less than 2.0 N / 15 mm, peeling may occur due to the load generated during wet heat treatment, resulting in a deterioration in barrier properties or leakage of contents. Furthermore, hand tearability may also be impaired.

[0071] [Adhesive layer] The adhesive layer used in the present invention can be a general-purpose laminating adhesive. For example, solvent-free, aqueous, or hot-melt adhesives based on poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, or casein can be used. Among these, urethane or polyester adhesives are preferred in terms of heat resistance and flexibility to accommodate dimensional changes of each resin. The adhesive layer can be applied by, for example, direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fountain coating, or other methods. To achieve sufficient adhesion, the coating weight after drying should be 1 to 8 g / m. 2 More preferably, it is 2 to 7 g / m 2 , and more preferably 3 to 6 g / m 2 The coating amount is 1g / m 2 If it is less than 8 g / m, it will be difficult to bond the entire surface, and the adhesive strength will decrease. 2 If the amount exceeds this, it takes a long time for the film to completely cure, unreacted material is likely to remain, and adhesive strength decreases.

[0072] [Print layer] Furthermore, the laminate of the present invention may have at least one or more layers of printed layers or other plastic resins and / or paper resins laminated between the resin film layer and the heat-sealable resin layer or on the outside thereof.

[0073] As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks are preferably used. 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, defoamers, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printing layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing 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.

[0074] According to the present invention, it is possible to obtain a laminated film which has excellent oxygen barrier properties and water vapor barrier properties after retort treatment, and which also has high interlayer adhesion and excellent lamination strength. [Example]

[0075] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. The films were evaluated by the following measurement methods.

[0076] The evaluation methods used in the present invention are as follows. (1) Creating a laminate A 70 μm thick unstretched polypropylene film (P1146, manufactured by Toyobo Co., Ltd.) was laminated as a thermal adhesive resin onto the inorganic thin film layer of the laminated film obtained in the Examples and Comparative Examples by dry lamination using a urethane-based two-component curing adhesive (a blend of "Takelac A525S" and "Takenate A50" manufactured by Mitsui Chemicals, Inc. in a ratio of 13.5:1), and aged at 40°C for 4 days to obtain laminates for Examples 1 to 4 and Comparative Examples 1 and 2. The thickness of the adhesive layer was approximately 4 μm after drying in all cases.

[0077] (2) Thickness (μm) The thickness of each layer was measured by cutting out a cross section of the laminate of the present invention solidified with a modified urethane resin using a microtome and observing it with a differential interference microscope.

[0078] (3) Anchor coat layer adhesion In each example and comparative example, each laminate obtained at the stage of laminating an anchor coat layer onto a resin film was used as a sample, and a 100 mm x 100 mm test piece was cut out from this sample, and the anchor coat layer was wiped off with acetone. The amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0079] (4) Composition and thickness of inorganic thin film layer In each example and comparative example, the laminate obtained at the stage of laminating the inorganic thin film layer was used as a sample, and the film thickness composition was measured using a fluorescent X-ray analyzer ("ZSX100e" manufactured by Rigaku Corporation) based on a previously prepared calibration curve. The excitation X-ray tube conditions were 50 kV and 70 mA.

[0080] (5) Moisture content The moisture content of the laminates obtained in each of the examples and comparative examples was measured using a heat-drying moisture content meter ("MS-70" manufactured by A&D Co., Ltd.).

[0081] Approximately 5 g of a sample of the laminated film obtained in each Example and Comparative Example was stored for 72 hours or more in an environment of 25±2°C and a relative humidity of 65±10%RH, then cut into a 50 x 50 mm square, placed on a measuring dish, and weighed. The sample weight [g] at this time was recorded as (Wa). After that, the sample was heated to 140°C, and the sample weight was measured when the weight change was 0.02% / sec or less. The sample weight [g] at this time was recorded as (Wb). The moisture content was calculated from the weight obtained at this time using the following formula (1). (Moisture content [%])=(Wa-Wb) / (Wa)×100...Equation (1) Each sample was measured three times, and the average value was used as the moisture content.

[0082] (6) Laminate strength The laminate prepared in (1) 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 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°, and the strength was measured both when water was dripped onto the peeled portion using a dropper (wet) and when it was not dripped (dry). On the other hand, the laminate prepared above was subjected to retort treatment by holding it in pressurized hot water at a temperature of 130°C for 30 minutes, and then immediately after that, a test piece was cut out from the resulting laminate after retort treatment in the same manner as above, and the laminate strength (after retort treatment) was measured in the same manner as above.

[0083] (7) Oxygen permeability The oxygen permeability of the laminate produced in (1) above was measured in accordance with JIS-K7126 Method B using an oxygen permeability measuring device ("OX-TRAN (registered trademark) 1 / 50" manufactured by MOCON) under an atmosphere of 23°C temperature and 65% RH. The oxygen permeability measurement was carried out in the direction in which oxygen permeates from the surface layer (C) side. On the other hand, the evaluation laminate was subjected to retort treatment by holding it in pressurized hot water at a temperature of 130°C for 30 minutes, and then dried at 40°C for 24 hours.The oxygen permeability (after retort treatment) of the resulting retort-treated laminate was measured in the same manner as above.

[0084] (8) Water vapor permeability The water vapor permeability of the laminate produced in (1) above was measured in accordance with JIS-K7129 Method B using a water vapor permeability measuring device ("PERMATRAN-W 3 / 33MG" manufactured by MOCON) under an atmosphere of a temperature of 40°C and a humidity of 90%RH. The water vapor permeability was measured in the direction in which water vapor permeated from the surface layer (C) side. On the other hand, the evaluation laminate was subjected to retort treatment by holding it in pressurized hot water at a temperature of 130°C for 30 minutes, and then dried at 40°C for 24 hours.The water vapor permeability (after retort treatment) of the resulting retort-treated laminate was measured in the same manner as above.

[0085] (9) Laminate strength deterioration rate The value calculated by the following formula (2) relative to the value measured in (6) above was taken as the deterioration rate of laminate strength. Laminate strength deterioration rate (%) = (laminate strength before retort treatment - laminate strength after retort treatment) / (laminate strength before retort treatment) × 100 Formula (2)

[0086] (10) Barrier value deterioration rate 7. The laminated film according to claim 5 or 6, wherein the barrier value deterioration rate after moist heat treatment, expressed by the following formula (3), is 150% or less, where (A) is the oxygen permeability measured under conditions of 23°C × 65% RH and (B) is the oxygen permeability measured under conditions of 23°C × 65% RH after performing retort treatment in which the film is kept in pressurized hot water at a temperature of 130°C for 30 minutes, relative to the values ​​measured in (7) and (8). Barrier value deterioration rate after heat and moisture treatment (%) = (B / A) × 100 Equation (3)

[0087] (11) Total reflection infrared absorption spectrum of anchor coat layer In each example and comparative example, the total reflection infrared absorption spectrum of the anchor coat layer surface of each laminate film obtained at the stage of laminating the anchor coat layer onto the substrate film was measured using an infrared spectrometer (BRUKER "ALPHA") by total reflection absorption infrared spectroscopy, and the peak intensity (P1) with an absorption maximum in the region of 1250 ± 50 cm-1 and the peak intensity (P2) with an absorption maximum in the region of 1070 ± 10 cm-1 were determined, and the intensity ratio (P1 / P2) was calculated. Each peak intensity was calculated from the peak height obtained by vertically connecting the baseline of zero absorbance and each peak top.

[0088] [Preparation of base film layer] Tables 1 to 3 show the details of the resin raw materials used in the production of the substrate film, the film forming conditions, and the raw material blending ratios.

[0089] [Table 1]

[0090] [Table 2]

[0091] [Table 3]

[0092] (OPP-1) The base layer (A) was made of 100.0 wt% polypropylene homopolymer PP-2 shown in Table 1. The surface layer (B) was made of a blend of 43.2 wt% polypropylene homopolymer PP-2 shown in Table 1, 52.0 wt% ethylene copolymerized polypropylene polymer PP-4 shown in Table 1, and 4.8 wt% antiblocking agent-containing masterbatch FTX0627G. The melt flow rate (g / 10 min) of the polypropylene resin composition constituting the surface layer (B) was 5.1. For the surface layer (C), a mixture of 93.6 wt % of polypropylene homopolymer PP-2 shown in Table 1 and 6.4 wt % of antiblocking agent-containing masterbatch FTX0627G was used. The base layer (A) was extruded using a 45 mm extruder, the surface layer (B) using a 25 mm extruder, and the surface layer (C) using a 20 mm extruder. The raw resins were melted at 250 ° C and co-extruded into a sheet from a T-die. The surface layer (B) was cooled and solidified so that it came into contact with a 30 ° C cooling roll, and then stretched 4.5 times in the machine direction (MD) at 125 ° C. Then, in a tenter, both ends of the film in the transverse direction (TD) were clamped with clips, preheated at 168 ° C., stretched 8.2 times in the transverse direction (TD) at 155 ° C., and heat-set at 165 ° C. while relaxing 6.7% in the transverse direction (TD). The film-forming conditions at this time were film-forming conditions a. In this way, a biaxially oriented polypropylene film having a structure of surface layer (B) / base layer (A) / surface layer (C) was obtained. The surface of the surface layer (B) of the biaxially oriented polypropylene film was corona treated using a corona treater manufactured by Softal Corona & Plasma GmbH at an applied current of 0.75 A, and then wound up on a winder. The thickness of the resulting 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).

[0093] (OPP-2) For the base layer (A), a polypropylene homopolymer PP-1 shown in Table 1 was used. The surface layer (B) was made by blending 43.2 wt% of polypropylene homopolymer PP-2 shown in Table 1, 52.0 wt% of ethylene copolymerized polypropylene polymer PP-4 shown in Table 1, and 4.8 wt% of antiblocking agent-containing masterbatch FTX0627G. The surface layer (C) was made by blending 93.6 wt% of polypropylene homopolymer PP-1 shown in Table 1 and 6.4 wt% of antiblocking agent-containing masterbatch FTX0627G. The base layer (A) was extruded using a 45 mm extruder, the surface layer (B) using a 25 mm extruder, and the surface layer (C) using a 20 mm extruder. The raw resins were melted at 250 ° C and co-extruded into a sheet from a T-die. The surface layer (B) was cooled and solidified so that it came into contact with a 30 ° C cooling roll, and then stretched 4.5 times in the machine direction (MD) at 135 ° C. Then, in a tenter, both ends of the film in the transverse direction (TD) were clamped with clips, preheated at 173 ° C., stretched 8.2 times in the transverse direction (TD) at 164 ° C., and heat-set at 171 ° C. while relaxing 6.7% in the transverse direction (TD). The film-forming conditions at this time were designated film-forming conditions b. In this way, a biaxially oriented polypropylene film having a structure of surface layer (B) / base layer (A) / surface layer (C) was obtained. The surface of the surface layer (B) of the biaxially oriented polypropylene film was corona treated using a corona treater manufactured by Softal Corona & Plasma GmbH at an applied current of 0.75 A, and then wound up on a winder. The thickness of the resulting 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).

[0094] (PET) The ester film E5100 manufactured by Toyobo Co., Ltd., having a thickness of 12 μm, was used.

[0095] [Creating anchor coat layer] The method for producing the anchor coat layer used in each of the examples and comparative examples will be described below.

[0096] [Coating liquid 1] A solution of 0.25 parts by weight of a silane coupling agent, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane ("KBM-603" manufactured by Shin-Etsu Chemical Co., Ltd.), dissolved in 1.48 parts by weight of acetone was mixed with 4.07 parts by weight of an isocyanate, a trimethylolpropane adduct of meta-xylylene diisocyanate ("Takenate D-110N" manufactured by Mitsui Chemicals, Inc.; solids content 75%), and stirred for 10 minutes using a magnetic stirrer. The resulting mixture was diluted with 69.55 parts by weight of methyl ethyl ketone and 14.03 parts by weight of 1-methoxy-2-propanol (hereinafter referred to as PGM), and 10.62 parts by weight of a polyester resin (DF-COAT GEC-004C manufactured by DIC Corporation; solids content 30%) was added to obtain the desired coating solution 1.

[0097] [Coating liquid 2] To a mixture of 42.83 parts by weight of purified water and 20.00 parts by weight of isopropanol, 6.67 parts by weight of a commercially available metaxylylene group-containing urethane resin dispersion (Mitsui Chemicals, Inc.'s "Takelac® WPB341"; solids content 30%) and 28.00 parts by weight of a commercially available polyester urethane resin dispersion (DIC Corporation's "Hydran® AP-80"; solids content 25%) were added and stirred for 10 minutes using a magnetic stirrer. To the resulting mixture, 2.50 parts by weight of a carbodiimide crosslinking agent (Nisshinbo Chemicals, Inc.'s "Carbodilite SV-02"; solids content 40%) was added to obtain the desired coating solution 2.

[0098] [Coating liquid 3] To 90 parts by mass of purified water, 10 parts by mass of fully saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: G Polymer OKS8049Q (saponification degree 99.0% or more, average polymerization degree 450)) was added, and the mixture was heated to 80°C with stirring, and then stirred for about 1 hour. The mixture was then cooled to room temperature, thereby obtaining a nearly transparent polyvinyl alcohol solution (PVA solution) with a solids content of 10%. 50.00 parts by mass of the above PVA solution was mixed with a mixed solution of 35.00 parts by mass of purified water and 15.00 parts by mass of 2-propanol, to obtain the target coating solution 2.

[0099] [Formation of inorganic thin film layer] The method for producing the inorganic thin film layer used in each of the examples and comparative examples will be described below. A composite oxide layer of silicon dioxide and aluminum oxide was formed on the anchor coat layer by electron beam evaporation. The evaporation sources used were 3-5 mm granular SiO2 (purity 99.9%) and Al2O3 (purity 99.9%). The inorganic thin film layer (SiO2 / Al2O3 composite oxide layer) in the film thus obtained (film containing an inorganic thin film layer / anchor coat layer) had a thickness of 13 nm. The composition of this composite oxide layer was Al2O3 / SiO2 (mass ratio) = 30 / 70.

[0100] Example 1 OPP-1 was used for the base film and Coating Solution 1 for the anchor coat layer, which were applied to the surface layer (B) of the resin film by gravure roll coating and dried at 130°C for 10 seconds. 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 2 days, and then an inorganic thin film layer was laminated thereon by the above-mentioned method to obtain the desired laminated film. Example 2 The target laminated film was obtained under the same conditions as in Example 1, except that the resin film was changed to OPP-2. Example 3 Anchor coat layer adhesion weight 0.20g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature. Example 4 The target laminated film was obtained under the same conditions as in Example 1, except that the composition of the inorganic thin film layer was changed to A12O3 / SiO2 (mass ratio) = 40 / 60. Example 5 The target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 2 was used for the anchor coat layer. (Comparative Example 1) The target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 3 was used for the anchor coat layer. (Comparative Example 2) The target laminated film was obtained under the same conditions as in Example 1, except that the substrate film was changed to PET.

[0101] A laminate film was prepared as described above. Furthermore, a laminate was prepared using the obtained laminate film as described in (1) above, and the structure and various evaluation results of the laminate film and the laminate were carried out. The results are shown in Table 4.

[0102] [Table 4A]

[0103] [Table 4B] [Industrial Applicability]

[0104] According to the present invention, it is possible to provide a laminated film that has excellent oxygen and water vapor barrier properties even after retort treatment and has adhesion that prevents delamination after retort treatment.

Claims

1. A laminated film in which an anchor coat layer and an inorganic thin film layer are laminated in this order on the surface layer (B) of a substrate film in which a surface layer (C), a substrate layer (A), and a surface layer (B) are laminated in this order, each containing 50% by mass of polypropylene in each layer, with or without other layers interposed therebetween, wherein the surface layer (B) is made of a resin composition containing two or more polypropylene resins with different crystallinity, and the anchor coat layer has a peak at 1250±50 cm in a total reflection infrared absorption spectrum. -1 The peak intensity (P1) has an absorption maximum in the region of 1070 ± 10 cm －１ The ratio (P1 / P2) of the peak intensity (P2) having the absorption maximum in the region of is in the range of 1.0 to 10.0, and the deposition amount is 0.50 g / m ２ a laminate comprising a laminate film and an olefin-based sealant layer laminated on the surface opposite to the surface layer (C), characterized in that the moisture content of the laminate film is less than 0.2% by mass, and the moisture content of the laminate film is 0.2% by mass or less; and the barrier value deterioration rate after moist heat treatment, expressed by the following formula, is 150% or less, when the oxygen permeability value of the laminate measured under conditions of 23°C x 65% RH is (A) and the oxygen permeability value of the laminate measured under conditions of 23°C x 65% RH after performing retort treatment in which the laminate is kept in pressurized hot water at a temperature of 130°C for 30 minutes is (B). Barrier value deterioration rate (%) after moist heat treatment=(B / A)×100 Formula (1).

2. The laminate according to claim 1 , wherein the inorganic thin film layer is made of a metal oxide.

3. 3. The laminate according to claim 1, wherein the laminate has a lamination strength of 2.0 N / 15 mm or more.

4. A packaging material comprising at least one layer of the laminate according to any one of claims 1 to 3.

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