Laminated thin films for inorganic thin film formation

Abstract

The objective of this invention is to provide a laminated film that is capable of forming a film composed of almost a single resin species with low environmental impact, mainly composed of polypropylene film, while having gas barrier properties required for packaging materials during the lamination of inorganic film layers. The present invention provides a laminated film for forming an inorganic thin film layer, which is a laminated film having a laminated coating layer on at least one side of a substrate layer mainly composed of polypropylene resin, characterized in that the aforementioned laminated film satisfies the following requirements (I) to (III): (I) The elongation at 130°C of the aforementioned laminated film is less than 10% in both the MD and TD directions; (II) The sum of the maximum peak height (Rp) and maximum valley depth (Rv) on the side surface of the coated layer, as determined by scanning probe microscopy, is less than 30.0 nm; (III) The coating adhesion amount is 0.10 g / m 2 or more 0.50g / m 2 or less.

Description

[Technical Field]

[0001] This invention relates to laminated films used in the packaging of food, pharmaceuticals, and industrial products. More specifically, it relates to laminated films that exhibit excellent gas barrier properties when made from easily recyclable materials and having an inorganic film layer. [Previous Technology]

[0002] In recent years, countries around the world, led by Europe, have strengthened regulations to reduce the use of single-use plastics. Against this backdrop, there has been an increased international awareness of resource recycling and a deepening of waste problems in emerging countries. Therefore, from the perspective of 3R (recycle, reuse, reduce), environmentally compliant products are also required for plastic packaging materials used in food, pharmaceuticals, and other products.

[0003] The properties required for the aforementioned environmentally friendly packaging materials include: (1) being made of easily recyclable materials; (2) having gas barrier properties that can block various gases and extend the shelf life; and (3) being made into a layered structure with low environmental impact (e.g., using less material and being recyclable as a single material).

[0004] In recent years, in order to make the aforementioned (1) and (3) possible, attention has been focused on the use of polypropylene film. Polypropylene film is widely used in a wide range of applications, such as packaging for food and various commodities, electrical insulation, and surface protection. Due to its molecular structure, polypropylene film exhibits high water vapor barrier properties. Furthermore, the sealant that is bonded to the substrate film is generally a polypropylene-based or polyethylene-based heat-sealing resin. Therefore, by using polypropylene film as the substrate and unstretched polypropylene sheet as the sealant, gas barrier properties can be achieved while achieving single-material packaging as a whole, resulting in an environmentally friendly packaging design that is easy to recycle.

[0005] However, regarding the gas barrier properties mentioned above (2), the polypropylene film has water vapor barrier properties, but compared with, for example, a transparent inorganic vapor-deposited polyester film with excellent water vapor barrier properties, it is not sufficient, and it has very poor oxygen barrier properties.

[0006] In contrast, gas barrier laminates are generally used on the surface of plastic substrate films such as polyester films to form metal films made of aluminum or inorganic films made of inorganic oxides such as silicon oxide and aluminum oxide. Among these, films formed of inorganic oxides such as silicon oxide, aluminum oxide, and mixtures thereof are widely used because they do not require aluminum foil, are transparent and allow the contents to be seen, and form very thin films that do not hinder recyclability.

[0007] In polypropylene films, a method for imparting gas barrier properties by laminating inorganic films has also been disclosed (for example, Patent Document 1). However, due to its molecular structure, the surface of polypropylene films has large unevenness, and the inorganic film layer has many cracks, which makes it impossible to exhibit sufficient gas barrier properties.

[0008] To address these problems, a method has been disclosed in which a polyvinyl alcohol polymer resin composition is used between a polypropylene film and an inorganic film layer to smooth the surface of the inorganic film layer, thereby imparting gas barrier properties (e.g., Patent Document 2). However, if a polyvinyl alcohol polymer resin composition is used, it is highly dependent on humidity, thus reducing oxygen barrier properties under high humidity, and water vapor barrier properties are not considered sufficient. Furthermore, to exhibit sufficient gas barrier performance, a layer mass of at least 0.5 g / m² is required. If the amount of adhesion increases, it may become a factor contributing to impurities during recycling, potentially making recycling itself difficult. Moreover, it is unsuitable from the viewpoint of single-material utilization. Furthermore, increasing the amount of adhesion also increases manufacturing costs. [Prior Art Documents] [Patent Documents]

[0009] Patent Document 1: International Publication No. 2017 / 221781; Patent Document 2: Japanese Patent Application Publication No. 2021-20392 [Summary of the Invention]

[0010] [The problem the invention aims to solve]

[0011] In the aforementioned Patent Document 1, the gas barrier performance is not sufficient. In Patent Document 2, the gas barrier performance under high humidity is not sufficient, and in order to demonstrate the effect, the film thickness needs to be increased, without considering the improvement of the processability of the coating layer, the environment, and the manufacturing cost. In other words, there has never been a material that meets all three of the following performance requirements for the aforementioned environmentally friendly packaging material: (1) containing recyclable materials as constituent materials; (2) having gas barrier performance that can block various gases and extend the shelf life; and (3) being made into a laminated structure that is easy to recycle and has a low environmental impact (single material).

[0012] This invention was made in response to the problems of the prior art. Specifically, the object of this invention is to provide a laminated film that is capable of forming a film composed almost entirely of a single resin species with low environmental impact, primarily composed of a polypropylene film, while simultaneously possessing the gas barrier properties required for packaging materials during the lamination of inorganic film layers. [Means for Solving the Problem]

[0013] The inventors discovered that by designing a laminated thin film that meets the required performance specifications, a thin film exhibiting good gas barrier properties can be provided during the lamination of inorganic thin film layers, and thus the present invention was completed.

[0014] That is, the present invention comprises the following components. 1. A laminated film for forming an inorganic thin film layer, which is a laminated film having a laminated coating layer on at least one side of a substrate layer mainly composed of polypropylene resin, characterized in that the laminated film satisfies the following requirements (I) to (III): (I) The elongation at 130°C of the laminated film is 10% or less in both the MD direction and the TD direction; (II) The sum of the maximum peak height (Rp) and the maximum valley depth (Rv) of the coating layer side surface, as measured by a scanning probe microscope, is 30.0 nm or less; (III) The amount of coating layer is 0.10 g / m2 or more and 0.50 g / m2 or less. 2. The laminated film for forming an inorganic thin film layer as described in 1., characterized in that the elongation at 100°C of the laminated film is 3% or less in both the MD direction and the TD direction. 3. A laminated thin film for forming an inorganic thin film layer as described in 1. or 2, characterized in that, in the total reflectance infrared absorption spectrum measured from the coated layer side of the aforementioned laminated thin film, the ratio (P2 / P1) of the peak intensity (P1) of the peak intensity (P2) of the peak intensity (P2) of the peak absorption in the region of 1720±10 cm⁻¹ is in the range of 0.1 to 30.0. 4. A laminated thin film, characterized in that a laminated inorganic thin film layer is present on the coated layer of the laminated thin film as described in any one of 1. to 3. 5. A laminated thin film, which is the laminated thin film as described in 4., characterized in that the aforementioned inorganic thin film layer contains Al and / or Si. [Effects of the Invention]

[0015] By means of this technology, the inventors can provide a laminated film that has the gas barrier properties required for packaging materials when laminating inorganic film layers, while taking the environment into account.

Implementation Method

[0017] [Form for implementing the invention]

[0018] Hereinafter, the present invention will be described in detail. A laminated film for forming an inorganic thin film layer is a laminated film having a laminated coating layer on at least one side of a substrate layer mainly composed of polypropylene resin, characterized in that the laminated film satisfies the following requirements (I) to (III): (I) The elongation at 130°C of the laminated film is 10% or less in both the MD direction and the TD direction; (II) The sum of the maximum peak height (Rp) and the maximum valley depth (Rv) of the coating layer side surface, as measured by a scanning probe microscope, is 30.0 nm or less; (III) The coating layer has an adhesion amount of 0.10 g / m² or more and 0.50 g / m² or less. Hereinafter, each layer of the laminated film will be described.

[0019] [Substrate Film Layer] The propylene resin stretched film used as the substrate film in this invention is preferably a biaxially stretched film. The biaxially stretched polypropylene resin film can be any known biaxially stretched polypropylene resin film, and its raw materials, mixing ratios, etc., are not particularly limited. For example, in addition to polypropylene homopolymers (propylene homopolymers), it can also be a mixture of propylene as the main component, and one or more random copolymers or block copolymers selected from α-olefins such as ethylene, butene, pentene, and hexene, or a mixture of two or more such polymers. Furthermore, for the purpose of property modification, known additives such as antioxidants, antistatic agents, and plasticizers can be added; for example, petroleum resins and terpene resins can be added.

[0020] Furthermore, the biaxially stretched polypropylene resin film used in this invention can be a single-layer film, or a laminated film consisting of multiple resin films comprising biaxially stretched polypropylene resin films. The type of laminate, the number of laminates, and the lamination method used in making the laminated film are not particularly limited, and can be arbitrarily selected from known methods depending on the purpose.

[0021] In this invention, the polypropylene resin constituting the substrate film is preferably a propylene homopolymer that is substantially free of comonomers. Even when comonomers are present, the amount of comonomers is preferably 0.5 mol% or less. The upper limit of the amount of comonomers is more preferably 0.3 mol%, and even more preferably 0.1 mol%. If it is within the above range, the crystallinity is improved, the dimensional change at high temperature is reduced, that is, the elongation at a certain temperature (hereinafter referred to as heating elongation) is reduced, and the heat resistance is improved. Furthermore, the comonomers may be contained in trace amounts within a range that does not significantly reduce the crystallinity.

[0022] The polypropylene resin constituting the substrate film is preferably a propylene homopolymer derived solely from propylene monomers, and even if it is a propylene homopolymer, it is most preferably free of heterogeneous bonds such as head-to-head bonds.

[0023] The lower limit of the xylene-soluble component of the polypropylene resin constituting the substrate film is preferably 0.1% by mass. The upper limit of the xylene-soluble component is preferably 7% by mass, more preferably 6% by mass, and even more preferably 5% by mass. If it is within the above range, the crystallinity is improved, the elongation at heating becomes smaller, and the heat resistance is improved.

[0024] In this invention, the lower limit of the melt flow rate (MFR) of the polypropylene resin (230°C, 2.16 kgf) is preferably 0.5 g / 10 min. More preferably, the lower limit of the MFR is 1.0 g / 10 min, further preferably 2.0 g / 10 min, particularly preferably 4.0 g / 10 min, and most preferably 6.0 g / 10 min. Within the above range, the mechanical load is low, making extrusion and stretching easier. The upper limit of the MFR is preferably 20 g / 10 min. More preferably, the upper limit of the MFR is 17 g / 10 min, further preferably 16 g / 10 min, and particularly preferably 15 g / 10 min. Within the above range, stretching becomes easier; thickness unevenness is reduced; stretching temperature and heat setting temperature can easily rise, resulting in lower heating elongation; and heat resistance is improved.

[0025] From the perspective of heat resistance, the aforementioned substrate film can be a uniaxially stretched film in the long side direction (MD direction) or the transverse direction (TD direction), but it is preferably a biaxially stretched film. In this invention, by at least uniaxial stretching, a film with low heat shrinkage at high temperatures and high heat resistance, which is unimaginable with conventional polypropylene films, can be obtained. Regarding the stretching method, examples include simultaneous biaxial stretching and successive biaxial stretching, but from the perspective of improving planarity, dimensional stability, and thickness uniformity, successive biaxial stretching is preferred.

[0026] Regarding the successive biaxial stretching method, polypropylene resin is heated and melted using a uniaxial or biaxial extruder at a resin temperature of 200°C to 280°C. The resin is then formed into a sheet using a T-die and extruded onto cooling rollers at a temperature of 10°C to 100°C to obtain an unstretched sheet. Next, the sheet is stretched 3.0 to 8.0 times in the longitudinal direction (MD) at a temperature of 120°C to 165°C. After preheating with a tenter frame, it is stretched 4.0 to 20.0 times in the transverse direction (TD) at a temperature of 155°C to 175°C. Furthermore, after biaxial stretching, a relaxation of 1% to 15% is allowed at a temperature of 165°C to 175°C while simultaneously performing a heat-setting temperature.

[0027] The substrate film used in this invention, in order to impart processability (e.g., rollability after lamination), preferably contains particles that form protrusions on the film surface. Examples of particles contained in the film include: inorganic particles such as silicon dioxide, kaolinite, talc, calcium carbonate, zeolite, and alumina; and heat-resistant polymer particles such as acrylic acid, PMMA, nylon, polystyrene, polyester, and benzoguanidine-formaldehyde condensate. From the perspective of transparency, a low particle content in the film is preferable, for example, preferably between 1 ppm and 1000 ppm. Furthermore, the preferred average particle diameter is 1.0 to 3.0 μm, more preferably 1.0 to 2.7 μm. The method for determining the average particle diameter here refers to taking photographs using a scanning electron microscope and measuring the horizontal Feret diameter using an image analyzer, expressing the average value. Furthermore, from the perspective of transparency, it is preferable to select particles with a refractive index similar to that of the resin used. Furthermore, to impart various functions to the film as needed, it may contain antioxidants, ultraviolet absorbers, antistatic agents, pigments, lubricants, nucleating agents, adhesives, antifogging agents, flame retardants, antiblocking agents, inorganic or organic fillers, etc.

[0028] In addition to the polypropylene resin used in this invention, other materials may be included in the film to improve the mechanical properties of the substrate film and the adhesion to the ink layer and adhesive layer deposited on the aforementioned gas barrier coating layer, without compromising the purpose of this invention. Examples include: polypropylene resins different from those described above, random copolymers of propylene and ethylene and / or α-olefins with 4 or more carbon atoms, and various elastomers.

[0029] In this invention, the thickness of the substrate film is arbitrarily set according to various applications, but the lower limit is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. On the other hand, the upper limit of the thickness is preferably 300 μm or less, more preferably 250 μm or less, even more preferably 200 μm or less, and particularly preferably 100 μm or less. When the thickness is thin, the processability is easily compromised. On the other hand, when the thickness is thick, not only is there a cost problem, but when it is wound into a roll for storage, poor planarity due to winding habits easily occurs.

[0030] From the viewpoint of visual recognizability of the contents, the haze of the polypropylene film used as the substrate of the present invention is preferably transparent, specifically, preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less. Haze tends to deteriorate in cases such as excessively high stretching temperature or heat setting temperature; high cooling roller (CR) temperature resulting in slow cooling rate of the stretched raw material sheet; and excessive low molecular weight. Therefore, by adjusting these factors, it is possible to control the haze within the aforementioned range.

[0031] Furthermore, the substrate film layer of the present invention may also be subjected to corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment, and well-known anchor coating treatment, printing, decoration, etc., as long as it does not impair the purpose of the present invention.

[0032] [Coating Layer] In this invention, a coating layer is provided during the lamination of inorganic thin film layers to exhibit sufficient gas barrier properties. By providing the coating layer, the performance of oligomers from polypropylene resin and anti-blocking agents can be suppressed. Furthermore, when other layers are laminated on the coating layer, the interlayer adhesion can be improved. In particular, during the formation of inorganic thin film layers, not only adhesion issues but also problems arise such as protrusions caused by surface irregularities preventing film formation and resulting in poor gas barrier properties. Furthermore, by using a gas-barrier material for the coating layer itself, the gas barrier performance of the laminated film can be significantly improved. Moreover, since the coating layer prevents hot water from penetrating the substrate, film whitening after boiling or cooking is also reduced.

[0033] In this invention, it is preferable that the coating layer has an adhesion amount of 0.10 to 0.50 g / m². This allows for uniform control of the coating layer during coating, resulting in a film with uneven coating and fewer defects. Furthermore, the coating layer helps suppress oligomer behavior and stabilizes haze after cooking. The adhesion amount of the coating layer is preferably 0.15 g / m² or more, more preferably 0.20 g / m² or more, further preferably 0.35 g / m² or more, preferably 0.50 g / m² or less, more preferably less than 0.50 g / m², and even more preferably 0.45 g / m² or less. If the adhesion amount of the coating layer exceeds 0.50 g / m², the gas barrier properties improve, but the cohesion within the coating layer becomes insufficient, and the uniformity of the coating layer decreases, resulting in uneven coating appearance and defects. Furthermore, in terms of processability, the thickness of the film may lead to adhesion and increased manufacturing costs. Moreover, there are concerns about its adverse impact on the recyclability of the film. On the other hand, if the protective layer thickness is less than 0.10 g / m², there is a risk that sufficient gas barrier properties and interlayer adhesion may not be achieved.

[0034] Regarding the resin composition used in the coating of the present invention, examples include resins such as urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins, which are formed by adding epoxy-based, isocyanate-based, and melamine-based curing agents. Furthermore, crosslinking agents such as silicone-based crosslinking agents, azirzoline compounds, carbodiimide compounds, and epoxy compounds can be included. In particular, urethane-based resins are preferred because, in addition to the barrier properties caused by the high cohesiveness of the urethane bonds themselves, they also possess flexibility due to the interaction between the polar groups and the inorganic film layer, and the presence of the amorphous portion. Therefore, damage can be suppressed when a bending load is applied. Polyester resins are also suitable as they can achieve the same effect. In the present invention, polyurethane-based resins consisting of polyester and isocyanate are preferred; furthermore, from the viewpoint of improving adhesion, the addition of silicone-based crosslinking agents is even more preferable.

[0035] (1) Carbamate Resin From the perspective of improving gas barrier properties, the carbamate resin used in this invention is preferably a carbamate resin containing aromatic or aromatic aliphatic diisocyanate components as the main constituent. Particularly preferred is a para-diisocyanate component. By using the above resin, the cohesive force of the carbamate bonds can be further improved through the stacking effect of the aromatic rings, resulting in good gas barrier properties.

[0036] In this invention, it is preferable that the proportion of aromatic or aromatic aliphatic diisocyanates in the urethane resin is 50 mol% or more (50 to 100 mol%) in 100 mol% of the polyisocyanate component. The total amount of aromatic or aromatic aliphatic diisocyanates is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, and even more preferably 80 to 100 mol%. If the total amount of aromatic or aromatic aliphatic diisocyanates is less than 50 mol%, there is a possibility that good gas barrier properties cannot be obtained.

[0037] (2) Crosslinking Agent In the urethane resin used in this invention, various crosslinking agents can be incorporated to improve the film's cohesiveness and moisture-heat resistance adhesion, without compromising gas barrier properties. Examples of crosslinking agents include: silicone crosslinking agents, azirzoline compounds, carbodiimide compounds, epoxy compounds, etc. Among these, silicone crosslinking agents are particularly preferred from the viewpoint of improving water resistance adhesion to inorganic film layers. As other crosslinking agents, azirzoline compounds, carbodiimide compounds, epoxy compounds, etc., can also be used in combination.

[0038] From the viewpoint of crosslinking inorganic and organic substances, silane coupling agents are preferred as silicon-based crosslinking agents. Examples of silane coupling agents include hydrolyzable alkoxysilane compounds, such as halogenated alkoxysilanes (e.g., 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, etc., chloroC2-4 alkyltriC1-4 alkoxysilanes), and epoxy-containing alkoxysilanes [e.g., 2-epoxypropyloxyethyltrimethoxysilane, 2-epoxypropyloxyethyltriethoxysilane, 3-epoxypropyloxyethyltriethoxysilane, etc.]. propyltrimethoxysilane, 3-epoxypropyltriethoxysilane and other epoxypropyloxyC2-4 alkyltriC1-4 alkoxysilanes, 3-epoxypropylmethyldimethoxysilane, 3-epoxypropylmethyldiethoxysilane and other epoxypropyloxydiC2-4 alkyldiC1-4 alkoxysilanes, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-Epoxycyclohexyl)propyltrimethoxysilane, etc. (Epoxycycloalkyl)C2-4 alkyltriC1-4 alkoxysilane, etc.; Alkoxysilanes with amino groups [2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc. aminoC2-4 alkyltriC1-4 alkoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, etc. aminodiC2-4 alkyldiC1-4 alkoxysilane, 2-[N-(2-aminoethyl)amino] Ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltriethoxysilane, etc. (2-aminoC2-4 alkyl)aminoC2-4 alkyltriC1-4 alkoxysilanes, 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane, 3-[N-(2-aminoethyl)amino]propylmethyldiethoxysilane, etc. (aminoC2-4 alkyl)aminodiC2-4 alkyldiC1-4 alkoxysilanes, etc.], containing mercapto groups Alkoxysilanes (such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc., mercapto-C2-4 alkyltriC1-4 alkoxysilanes, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc., mercapto-diC2-4 alkyldiC1-4 alkoxysilanes, etc.), alkoxysilanes with vinyl groups (such as vinyltrimethoxysilane, vinyltriethoxysilane, etc., vinyltriC1-4 alkoxysilanes, etc.), and alkoxysilanes with vinyl unsaturated bonds. [2-(meth)propenyloxyethyltrimethoxysilane, 2-(meth)propenyloxyethyltriethoxysilane, 3-(meth)propenyloxypropyltrimethoxysilane, 3-(meth)propenyloxypropyltriethoxysilane, etc. (meth)propenyloxyC2-4alkyltriC1-4alkoxysilane, 3-(meth)propenyloxypropylmethyldimethoxysilane, 3-(meth)propenyloxypropylmethyldiethoxysilane, etc. (meth)propenyloxydiC2-4alkyldiC1-4alkoxysilane, etc.] etc. These silane coupling agents can be used alone or in combination of two or more. Among these silane coupling agents, those containing amino groups are preferred.

[0039] Preferably, the silicon-based crosslinking agent is added to the coating layer at 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. By adding the silane coupling agent, the membrane hardens and its cohesion is enhanced, resulting in a membrane with excellent water resistance and adhesion. Furthermore, it is expected to prevent the formation of oligomers. If the addition amount exceeds 3.00% by mass, the membrane hardens and its cohesion is enhanced, but some unreacted portions may also be produced, potentially reducing interlayer adhesion. On the other hand, if the addition amount is less than 0.05% by mass, sufficient cohesion may not be obtained.

[0040] (3) Polyester Resin The polyester resin used in this invention is manufactured by polycondensation of a polycarboxylic acid component and a polyol component. Regarding the molecular weight of the polyester, there are no particular limitations as long as it can impart sufficient toughness, coating suitability, and solvent solubility to the coating material, but the number average molecular weight is 1000 to 50000, more preferably 1500 to 30000. There are also no particular limitations regarding the functional groups at the ends of the polyester; it may have alcohol ends, carboxylic acid ends, or both. However, when using an isocyanate-based curing agent, it is necessary to prepare a polyester polyol with alcohol ends as the main component.

[0041] The Tg of the polyester used in this invention is preferably 10°C or higher. This is because if the temperature is lower than this, the resin becomes sticky after the coating operation, making it prone to sticking and making the winding operation after coating difficult. This is because if the Tg is lower than 10°C, even with the addition of anti-blocking materials, even under high pressure near the core, anti-blocking becomes difficult. A more preferred Tg temperature is 15°C or higher, and more preferably 20°C or higher.

[0042] The polyester used in this invention is obtained by polycondensation of a polycarboxylic acid component and a polyol component. [Polycarboxylic acid component] The polycarboxylic acid component of the polyester used in this invention is characterized by containing at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. By forming an ortho-ortho orientation, the solubility in solvents is improved, allowing for uniform coating of the substrate. The uniformly coated coating system exhibits less variation in barrier properties, which helps to suppress oligomer whitening. Furthermore, by forming an ortho-ortho orientation, a film with excellent flexibility is formed, and interfacial adhesion is improved, thereby reducing damage to the substrate caused by damp heat treatment, which is related to the suppression of oligomers. Examples of aromatic polycarboxylic acids or their anhydrides in which the carboxylic acid is substituted at the ortho position include: phthalic 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-anthracarboxylic acid or its anhydride. These compounds may have substituents on any carbon atom of the aromatic ring. Examples of such substituents include: chloro, bromo, methyl, ethyl, isopropyl, hydroxy, methoxy, ethoxy, phenoxy, methylthio, phenylthio, cyano, nitro, amino, phthalimide, carboxyl, carboxylic acid, N-ethylcarboxylic acid, phenyl, or naphthyl. Furthermore, polyester polyols containing 70-100 mol% of these polycarboxylic acids relative to 100 mol% of the total composition exhibit high barrier properties and excellent solubility as a solvent required for coating materials, making them particularly advantageous.

[0043] In this invention, other polycarboxylic acid components can be copolymerized without impairing the effects of the invention. Specifically, for aliphatic polycarboxylic acids, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, etc., can be used alone or in a mixture of two or more; for polycarboxylic acids containing unsaturated bonds, maleic anhydride, maleic acid, fumaric acid, etc., can be used alone or in a mixture of two or more; for alicyclic polycarboxylic acids, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc., can be used alone or in a mixture of two or more; for aromatic polycarboxylic acids, terephthalic acid, isophthalic acid, pyromellitic acid, trimellitic acid, etc., can be used alone or in a mixture of two or more. Polycarboxylic acids include 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalenedicarboxylic acid, biphenyl dicarboxylic acid, biphenyl dicarboxylic acid and their anhydrides, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid and the anhydrides or ester-forming derivatives of such dicarboxylic acids; p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid and the ester-forming derivatives of such dihydroxycarboxylic acids, etc. From the viewpoint of organic solvent solubility and gas barrier properties, succinic acid, 1,3-cyclopentanedicarboxylic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, and biphenyl dicarboxylic acid are preferred.

[0044] [Polyol Components] The polyol components of the polyester used in this invention are not particularly limited as long as they can synthesize polyesters exhibiting gas barrier filling properties, but preferably contain at least one polyol component selected from the group consisting of ethylene glycol, propylene glycol, butanediol, neopentyl glycol, cyclohexanediol, and 1,3-dihydroxyethylbenzene. It is presumed that the fewer carbon atoms between oxygen atoms, the less the molecular chain will become excessively soft, and the more difficult it is for oxygen to penetrate; therefore, ethylene glycol is preferably used as the main component.

[0045] In this invention, it is preferred to use the aforementioned polyol components. However, other polyol components may be copolymerized without impairing the effects of this invention. Specifically, examples of diols include 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethyl propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of tri- or higher alcohols include glycerol, trimethylolpropane, trimethylolethane, 2-hydroxyethyl isocyanate, 1,2,4-butanetriol, neopentyl tertrol, and dinepentyl tertrol. In particular, polyesters containing glycerol and 2-hydroxyethyl isocyanate, due to their branched structure, have a moderately high crosslinking density, good solubility in organic solvents, and excellent barrier properties, making them especially suitable for use.

[0046] Examples of catalysts 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 tetraisopropyl titanate and tetrabutyl titanate; and acid catalysts such as tetrabutyl zirconate and zirconium oxide. Preferably, a combination of the above-mentioned titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, which have high activity for ester reactions, and the above-mentioned zirconium oxide catalysts is used. The amount of the aforementioned catalyst, relative to the total mass of the reaction raw materials used, is 1 to 1000 ppm, more preferably 10 to 100 ppm. If it is less than 1 ppm, it is difficult to obtain the effect of a catalyst; if it is more than 1000 ppm, there is a problem of hindering the aminocarbamate reaction when using isocyanate curing agents.

[0047] (4) Isocyanate-based curing agent In this invention, when polyester resin is used as the main agent constituting the coating layer, an isocyanate-based curing agent is required to form a carbamate resin. In this case, since the coating layer becomes cross-linked, it has the advantages of improved heat resistance, abrasion resistance, and rigidity. Therefore, it is also easy to use for boiling and retort packaging. On the other hand, the liquid cannot be reused after mixing the curing agent, and there is also the problem that a curing (aging) step is required after coating. In terms of advantages, as a simple protective varnish, it can be used for example: there is no risk of thickening of the coating liquid, the coating manufacturing process is easy to manage, the coating liquid can be diluted and reused, and a curing step (so-called aging step) is not required. At this time, even if the end of the polyester used is a polyol, a polycarboxylic acid, or a mixture of the two, it can be used without problems. On the other hand, since the resin of the coating layer is linear, there is a situation where the heat resistance and abrasion resistance are insufficient; and there is a situation where it is difficult to use for boiling and retort packaging.

[0048] When a hardener is used in the coating layer, since it is a coating of a thin film, from the viewpoint of the film's heat resistance, an isocyanate-based hardener is preferred. In this case, the resin component of the coating material needs to be a polyester polyol. On the other hand, when an epoxy compound is used as the hardener, a polyester polycarboxylic acid is required. In these cases, since the coating layer becomes cross-linked, it has advantages in heat resistance, abrasion resistance, and increased rigidity. Therefore, it is also easy to use for boiling and retorting packaging. On the other hand, since the liquid cannot be reused after mixing the hardener, there is also the problem that a hardening (aging) step is required after coating.

[0049] The polyisocyanate compound used in this invention, when the polyester has hydroxyl groups, at least a portion of it reacts to form a carbamate structure, thus becoming highly polar as a resin component. This causes the polymer chains to aggregate, thereby further enhancing the gas barrier function. Furthermore, when the resin of the coating material is a linear resin, crosslinking with trivalent or higher polyisocyanates can impart heat resistance and abrasion resistance. The polyisocyanate compound used in this invention can be any of diisocyanate, trivalent or higher polyisocyanate, low-molecular-weight compound, or high-molecular-weight compound. However, if a portion of the backbone contains an aromatic ring or an aliphatic ring, it is preferable from the viewpoint of enhancing the gas barrier function. For example, examples of isocyanates having aromatic rings include toluene diisocyanate, diphenylmethane diisocyanate, styrene diisocyanate, and naphthalene diisocyanate; examples of isocyanates having aliphatic rings include hydrogenated styrene diisocyanate, hydrogenated toluene diisocyanate, isoflavone diisocyanate, norcamphene diisocyanate, or trimers of such isocyanate compounds, and compounds containing terminal isocyanate groups obtained by reacting excess of such isocyanate compounds with low molecular weight active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerol, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, or high molecular weight active hydrogen compounds such as various polyester polyols, polyether polyols, and polyamides.

[0050] The coating method of the resin composition for the coating layer is not particularly limited as long as it is a method of forming a layer by coating on the surface of a film. Common coating methods such as gravure coating, reverse roll coating, wire rod coating, and die coating can be used.

[0051] When forming the coating layer, it is preferable to heat-dry it after coating with the resin composition for the coating layer. The drying temperature is preferably 100-145°C, more preferably 110-140°C, and even more preferably 110-130°C. If the drying temperature is less than 100°C, the coating layer may be insufficiently dried. On the other hand, if the drying temperature exceeds 145°C, the film may be overheated, becoming brittle, shrinking, and having poor processability. In particular, it is especially desirable to first volatilize the solvent at a lower temperature of 80-110°C after coating, and then dry it at 120°C or higher, to obtain a uniform film. Furthermore, unlike drying, it is even more effective to add additional heat treatment in the low-temperature region when forming the coating layer.

[0052] [Inorganic Thin Film Layer] The laminated thin film of the present invention can have an inorganic thin film layer on the surface of the aforementioned coated layer. The inorganic thin film layer is a thin film made of metal or inorganic oxide. There are no particular limitations on the material forming the inorganic thin film layer if it is capable of forming a thin film, but from the viewpoint of gas barrier properties, the following inorganic oxides are more suitable: aluminum, silicon dioxide, alumina, and mixtures of silicon dioxide and alumina. In this composite oxide, the mixing ratio of silicon dioxide to alumina, in terms of the mass ratio of the metal components, is preferably in the range of 20 to 70% by mass of Al. If the Al concentration is less than 20% by mass, the water vapor barrier properties will decrease. On the other hand, if it exceeds 70% by mass, the inorganic thin film layer tends to harden, and there is a risk that the film may be damaged during secondary processing such as printing and lamination, resulting in a decrease in gas barrier properties. Furthermore, when the Al concentration is 100% by mass, the water vapor barrier properties become good, but because it is a single material, it tends to have a smooth surface, resulting in poor lubrication and making it prone to processing problems (wrinkles, bumps, etc.). In addition, the silicon oxide referred to here refers to various silicon oxides such as SiO and SiO2, or mixtures thereof, while the aluminum oxide refers to various aluminum oxides such as AlO and Al2O3, or mixtures thereof.

[0053] The thickness of the inorganic thin film layer is 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 becomes difficult to obtain satisfactory gas barrier properties. On the other hand, even if it is made excessively thicker than 100 nm, it is not possible to obtain a corresponding improvement in gas barrier properties, and it becomes disadvantageous in terms of bending resistance and manufacturing cost.

[0054] There are no particular limitations on the method for forming the inorganic thin film layer. Well-known vapor deposition methods such as physical vapor deposition (PVD), sputtering, and ion plating, or chemical vapor deposition (CVD) can be appropriately used. Hereinafter, a typical method for forming an inorganic thin film layer will be described using silicon oxide and aluminum oxide thin films as examples. For example, when using vacuum vapor deposition, a mixture of SiO2 and Al2O3, or a mixture of SiO2 and Al, is suitable as the vapor deposition material. For such vapor deposition materials, particles are usually used, but in this case, it is desirable that the size of each particle is such that the pressure during vapor deposition does not change; a preferred particle size is 1 mm to 5 mm. Heating can be achieved using resistance heating, high-frequency induction heating, electron beam heating, laser heating, etc. Furthermore, oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, etc., can be introduced as reactant gases, or reactive vapor deposition can be performed using ozone addition, ion assistance, etc. Furthermore, it is possible to apply a bias voltage to the substrate (the deposited thin film) or to arbitrarily change the film formation conditions, such as heating or cooling the substrate. The deposition material, reactant gas, bias voltage of the substrate, heating, and cooling can also be changed in the same way when using sputtering or CVD methods.

[0055] [Protective Layer] In this invention, in cases where gas barrier properties are further required, or where processing such as printing is required, a protective layer can be provided on the aforementioned inorganic thin film layer. The inorganic thin film layer is not a completely dense film, but rather has scattered tiny defects. By coating the inorganic thin film layer with the specific protective layer resin composition described later to form a protective layer, the resin in the protective layer resin composition penetrates into the defects of the inorganic thin film layer, resulting in a stable gas barrier effect. Furthermore, by using a gas barrier material itself for the protective layer, the gas barrier performance of the laminated film is also significantly improved. However, attention should be paid to the increased cost due to the added steps caused by the protective layer, and the environmental impact caused by the materials used. Also, attention should be paid to the changes in physical properties such as surface roughness due to the protective layer.

[0056] The amount of protective layer adhesion is preferably set to 0.10 to 0.50 g / m². This allows for uniform control of the protective layer during coating, resulting in a film with less uneven coating and fewer defects. Furthermore, the cohesion of the protective layer itself is improved, and the adhesion between the inorganic film layer and the protective layer becomes stronger. If the amount of protective layer adhesion exceeds 0.50 g / m², gas barrier properties are improved, but the cohesion within the protective layer becomes insufficient, and the uniformity of the protective layer also decreases. Therefore, there is a risk of uneven coating appearance, defects, or insufficient gas barrier properties and adhesion. On the other hand, if the film thickness of the protective layer is less than 0.10 g / m², there is a risk that sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0057] As for the resin composition used in the protective layer formed on the surface of the inorganic film layer of the laminated film of the present invention, examples include resins such as vinyl alcohol, carbamate, polyester, acrylic, titanium, isocyanate, imine, and polybutadiene, which are formed by adding epoxy, isocyanate, and melamine curing agents.

[0058] The method of coating the resin composition for the protective layer is not particularly limited as long as it is a method of forming a layer by coating it on the surface of a film. Common coating methods such as gravure coating, reverse roll coating, wire rod coating, and die coating can be used.

[0059] [Laminated Films] The laminated films of the present invention exhibit the following film properties. Furthermore, the following properties were measured and evaluated by the methods described later in the examples.

[0060] The thickness of the laminated film of the present invention is preferably 9 μm or more and 200 μm or less, more preferably 10 μm or more and 150 μm or less, even more preferably 12 μm or more and 100 μm or less, and particularly preferably 15 μm or more and 80 μm or less.

[0061] Furthermore, the thickness of the entire substrate layer relative to the overall thickness of the film is preferably 50% or more and 99% or less, more preferably 60% or more and 97% or less, particularly preferably 70% or more and 95% or less, and most preferably 80% or more and 92% or less.

[0062] In the laminated film of the present invention, it is preferable that the ratio (P2 / P1) of the peak intensity (P1) with maximum absorption in the 1720±10 cm⁻¹ region and the peak intensity (P2) with maximum absorption in the 1070±10 cm⁻¹ region in the total reflectance infrared absorption spectrum of the coated layer is in the range of 0.1 to 30.0. More preferably, it is in the range of 0.1 to 20.0, and even more preferably, it is in the range of 0.2 to 10.0. The peak at 1720±10 cm⁻¹ originates from the C=O structure of aromatic or aromatic aliphatic ester skeletons and serves as an indicator of the amount of polyester skeleton. Furthermore, the peak at 1070±10 cm⁻¹ originates from the C-OH peak and serves as an indicator of the amount of hydroxyl groups originating from the polyester in the coated layer. (P2 / P1) represents the ratio of hydroxyl groups in the polyester backbone. By ensuring this ratio falls within the aforementioned range, the film's toughness is not compromised, and the film becomes highly polarized. During the deposition of the inorganic film layer, the adhesion between the coating layer and the inorganic film layer is increased, resulting in maximum gas barrier performance. If (P2 / P1) is less than 0.1, the amount of hydroxyl groups in the coating layer is insufficient, leading to a sparse film formation in the inorganic film layer and difficulty in achieving gas barrier properties. On the other hand, if (P2 / P1) exceeds 30.0, the bonding force with the inorganic film layer becomes stronger, but cross-linking in the coating layer does not occur, resulting in reduced film-forming properties and brittleness. To ensure that the (P2 / P1) value of the coating layer falls within the aforementioned specified range, the aforementioned materials must be used to achieve the aforementioned specified adhesion amount, and the material blending ratio must be within the aforementioned suitable range, combined with the drying and heat treatment conditions described later.

[0063] In the laminated film of the present invention, the heating elongation at 100°C is preferably 3% or less in both the MD and TD directions. This prevents the substrate from elongating due to heat from the evaporation source and vapor-deposited particles during the deposition of the inorganic thin film layer, thereby further improving gas barrier performance and quality. The heating elongation at 100°C in both the MD and TD directions is preferably 2.8% or less, more preferably 2.5% or less, and preferably 0%. If the heating elongation at 100°C exceeds 3%, the laminated film may deform due to heat from the evaporation source and vapor-deposited particles during the deposition of the inorganic thin film layer, resulting in reduced gas barrier performance or decreased quality. Furthermore, the heating elongation at 130°C is preferably 10% or less in both the MD and TD directions. The heating elongation in the MD and TD directions at 130°C is preferably 8% or less, more preferably 7% or less, further preferably 6.5% or less, and the lower limit is preferably 0%. In this invention, the heating elongation is a value measured by the TMA method, and more specifically, the method described in the embodiments.

[0064] The sum of the maximum peak height (Rp) and maximum valley depth (Rv) of the coated layer side surface of the laminated film of the present invention, as determined by scanning probe microscopy (AFM), is preferably 0.1 nm to 30.0 nm. The maximum peak height (Rp) and maximum valley depth (Rv) are determined by measuring the image obtained using scanning probe microscopy (AFM) in dynamic mode within a range of 2 μm in both the X and Y directions, after correction (removal of tilt, line fitting, and noise lines), according to the definitions described in JIS-B0601 (1994).

[0065] The maximum peak height (Rp) and maximum valley depth (Rv) within a 2μm square area caused by AFM are indicators of the unevenness of the resin itself, other than the larger peaks and valleys formed by anti-blocking agents and lubricants. When an inorganic film layer is formed on the surface of the coated layer, this unevenness may lead to poor formation and cracks in the inorganic film layer. When the combined maximum peak height (Rp) and maximum valley depth (Rv) exceed 30.0 nm, the surface unevenness is large, causing the inorganic film to peel off during formation and resulting in poor barrier properties. The combined maximum peak height (Rp) and maximum valley depth (Rv) on the side surface of the coated layer is preferably 20.0 nm or less, more preferably 10.0 nm or less, and most preferably 7.0 nm or less.

[0066] Preferably, the oxygen permeability at 23°C × 65%RH during the deposition of inorganic thin film layers in the laminated thin film of the present invention is 15 cc / m² / d / atm or less. More preferably, it is 10 cc / m² / d / atm or less, and even more preferably, it is 8 cc / m² / d / atm or less. The preferred lower limit of oxygen permeability is 0.1 cc / m² / d or more. Furthermore, the water vapor permeability at 40°C × 90%RH is preferably 3.0 g / m² / d or less. More preferably, it is 2.5 g / m² / d or less, and even more preferably, it is 2.0 g / m² / d or less. The preferred lower limit of water vapor permeability is 0.1 g / m² / d or more.

[0067] [Laminated Body] When using the laminated film of the present invention as a packaging material, it is preferable to form a laminated body that forms a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on the side of the coating layer or inorganic film layer, but it may also be provided on the outside of the substrate film layer (the side opposite to the inorganic film forming surface). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. As for the thermoplastic polymer that forms the heat-sealable resin layer, it can be any polymer that can sufficiently exhibit sealant adhesion, such as olefin-based polyethylene resins like HDPE, LDPE, and LLDPE; polypropylene resins; ethylene-vinyl acetate copolymers; ethylene-α-olefin random copolymers; ionomer resins, etc. Among these, from the viewpoints of durability, sealing strength, price, and single-material availability, LLDPE or polypropylene resin, which have high versatility, is particularly preferred. The thickness of the sealant layer is preferably 20–100 μm, more preferably 30–90 μm, and even more preferably 40–80 μm. If the thickness is thinner than 20 μm, there is a possibility that sufficient sealing strength cannot be obtained, the bag will lack toughness, and it will be difficult to handle. On the other hand, if the thickness exceeds 100 μm, the bag will be more tough, which will reduce its handlingability and increase the price.

[0068] [Adhesive Layer] The adhesive layer used in this invention can be a general-purpose lamination adhesive. Solvent-free, water-based, and hot-melt adhesives with components such as polyurethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, and casein are suitable. Among these, urethane or polyester adhesives are preferred, considering heat resistance and flexibility to adapt to the thermal elongation of each substrate. Regarding the aforementioned adhesive layer lamination method, coating can be performed using methods such as direct gravure coating, reverse gravure coating, kiss coating, mold coating, roller coating, dip coating, knife coating, spray coating, fountain coating, and other methods. To exhibit sufficient adhesion, the coating amount after drying is preferably 1 to 8 g / m², more preferably 2 to 7 g / m², and even more preferably 3 to 6 g / m². If the coating amount is less than 1 g / m², it becomes difficult to achieve full-surface adhesion, resulting in reduced adhesion. Furthermore, if it exceeds 8 g / m², complete curing of the film takes longer, unreacted substances are more likely to remain, and adhesion is reduced.

[0069] [Printed Layer] Furthermore, in the laminated film of the present invention, at least one or more printed layers, other plastic substrates and / or paper substrates may be laminated between or on the outside of the substrate film layer and the heat-sealing resin layer.

[0070] Regarding the printing ink used to form the printing layer, water-based and solvent-based resin-containing printing inks are more suitable. Examples of resins used in this printing ink include acrylic resins, carbamate resins, polyester resins, vinyl chloride resins, vinyl acetate copolymer resins, and mixtures thereof. The printing ink may contain known additives such as antistatic agents, opacifiers, UV absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinking agents, anti-blocking agents, and antioxidants. The printing method used to form the printing layer is not particularly limited; known printing methods such as offset printing, gravure printing, and screen printing can be used. The solvent after printing can be dried using known drying methods such as hot air drying, hot roller drying, and infrared drying. [Example]

[0071] Next, the present invention will be described in further detail by way of examples, but the present invention is not limited to the following examples. In addition, the evaluation of the thin film is carried out by the following measurement method.

[0072] [Determination Method]

[0073] (1) Method for measuring total reflectance infrared absorption spectrum of laminated films In each embodiment and comparative example, the total reflectance infrared absorption spectrum of each laminated film monomer obtained in the stage of laminating a coating layer on a substrate film is measured by total reflectance absorption infrared spectroscopy. The peak intensity (P1) with maximum absorption in the region of 1720±10cm-1 and the peak intensity (P2) with maximum absorption in the region of 1070±10cm-1 are calculated, and their intensity ratio (P2 / P1) is calculated. The calculation of the intensity of each peak is performed from the peak height of the vertically connected baseline where the absorbance is zero.

[0074] (2) Maximum peak height (Rp) and maximum valley depth (Rv) (nm) In each embodiment and comparative example, the maximum peak height (Rp) and maximum valley depth (Rv) of the coated layer side of the obtained laminated film were measured using a scanning probe microscope (Shimadzu SPM-9700). The measurements were performed using a phase mode with a measurement length of 2 μm in both the X and Y directions. After correcting (removing tilt, line fitting, and noise lines) the obtained image, the values ​​were determined according to the definition described in JIS-B0601 (1994).

[0075] (3) Coating adhesion amount In each embodiment and comparative example, each laminated film obtained in the stage of laminating the coating on the substrate film is used as a sample. A 100mm×100mm test piece is cut from the sample and the coating is wiped with acetone. The adhesion amount is calculated from the mass change of the film before and after wiping.

[0076] (4) Elongation at Heat (%) In each embodiment and comparative example, the elongation at heat was determined by temperature-modulated TMA using a thermomechanical analysis apparatus (Shimadzu Corporation "TMA-60"). The elongation at heat in the MD direction was prepared by cutting strips from the laminated films of the embodiments and comparative examples with a width of 30 mm in the MD direction and a width of 4 mm in the TD direction. The measurement conditions were set as follows: the distance between the clamps was 10 mm, the measurement temperature range was 30°C to 150°C, the heating rate was 20°C / min, and the tensile load applied to the sample sheet was 0.39 N. The elongation at heat was determined from the distance between the clamps (mm) when the furnace temperature reached 100°C and the distance between the clamps (mm) when the furnace temperature reached 130°C. The elongation at heat in the TD direction was prepared by cutting strips from the laminated films of the embodiments and comparative examples with a width of 30 mm in the TD direction and a width of 4 mm in the MD direction. The measurement conditions were as follows: the distance between the clamps was set to 10 mm, the measurement temperature range was set to 30℃ to 150℃, the heating rate was set to 20℃ / min, and the tensile load applied to the sample was set to 0.39 N. The elongation at heating was calculated from the distance between the clamps (mm) when the furnace temperature reached 100℃ and the distance between the clamps (mm) when the furnace temperature reached 130℃. The elongation at heating (S100) at 100℃ and the elongation at heating (S130) at 130℃ were each calculated using the following formulas: (S100) = (distance between clamps at 100℃ - distance between clamps before heating) / distance between clamps before heating × 100 (S130) = (distance between clamps at 130℃ - distance between clamps before heating) / distance between clamps before heating × 100

[0077] (5) Composition of inorganic thin film layer. Film thickness was determined using a fluorescence X-ray analysis apparatus (Rigaku Corporation "ZSX100e") with a pre-prepared calibration curve for the laminated thin films (after film deposition) obtained in the Examples and Comparative Examples. In addition, the conditions for exciting the X-ray tube were set to 50 kV and 70 mA.

[0078] (6) Evaluation method for oxygen penetration In the laminated films (after film lamination) obtained in each embodiment and comparative example, the oxygen penetration was measured using an oxygen penetration measuring device (MOCON Corporation "OX-TRAN (registered trademark) 1 / 50") according to JIS-K7126 B method at an environment of 23°C and 65%RH. In addition, the oxygen penetration was measured in the direction in which oxygen penetrates from the substrate layer side.

[0079] (7) Evaluation method for water vapor transmission In the laminated films (after film lamination) obtained in each embodiment and comparative example, the water vapor transmission was measured in an environment of 40°C and 90%RH using a water vapor transmission measuring device (MOCON "PERMATRAN-W 3 / 33MG") according to JIS-K7129 B method. In addition, the water vapor transmission was measured in the direction in which water vapor penetrates from the substrate layer side.

[0080] (8) Appearance Evaluation Method In each embodiment and comparative example, the appearance of the side surface of the coated layer is visually evaluated after the coated layer is laminated. ○: No defects occur, which is good ×: Any defect such as wrinkles, uneven coating, or rejection occurs

[0081] [Preparation of substrate film layer] The details of the polypropylene resin raw materials used in the preparation of the polyolefin substrate film, the film preparation conditions, and the raw material blending ratio are shown in Tables 1 to 4.

[0082] [Table 1] Polypropylene resin PP-1 PP-2 PP-3 raw material monomers propylene propylene propylene Resin stereoregularity (ratio of racemic five-unit components (%)) 98.7 98.9 98.4 MFR (g / 10 min, 230℃, 2.16 kgf) 7.6 1.9 3.0 Molecular weight (Mn) 67,500 80,000 79,400 Molecular weight (Mw) 270,000 360,000 312,000 Molecular weight distribution (Mw / Mn) 4.0 4.5 3.9 DSC melting peak temperature (°C) 168.0 163.3 163.9 DSC melting peak area (J / g) 105.2 94.3 98.6

[0083] [Table 2] Masterbatch A Product name of masterbatch FTX0627G Anti-blocking agent in masterbatch Silicon dioxide particles Average particle size (μm) of anti-blocking agents 2.7 Anti-blocking agent content in masterbatch (ppm by weight) 50000 Polypropylene resin in the masterbatch MFR (g / 10 min, 230℃, 2.16 kgf) 3.0

[0084] [Table 3] Thin film forming conditions a b Melting resin temperature (°C) 250 250 Cooling roller temperature (°C) 30 30 Longitudinal stretch ratio (times) 4.5 4.5 Longitudinal tensile temperature (°C) 135 125 Width-direction stretch ratio (times) 8.2 8.2 Width-direction stretching preheating temperature (°C) 173 168 Tensile temperature in the width direction (°C) 164 155 Heat setting temperature (°C) 171 165 Width easing rate (%) 6.7 6.7

[0085] [Table 4] OPP-1 OPP-2 Substrate layer (A) raw material PP-1 weight% 100.00 0.00 PP-2 weight% 0.00 40.00 PP-3 weight% 0.00 60.00 thickness μm 18 18 Surface layer (B) raw material PP-1 weight% 96.4 0.0 PP-2 weight% 0.0 0.0 PP-3 weight% 0.0 96.4 Masterbatch containing antiblocking agent weight% 3.6 3.6 Masterbatch - A A thickness μm 1.0 1.0 Surface treatment Corona treatment Corona treatment Surface layer (C) raw material PP-1 weight% 94.0 0.0 PP-2 weight% 0.0 0.0 PP-3 weight% 0.0 94.0 Masterbatch containing antiblocking agent weight% 6.0 6.0 Masterbatch - A A thickness μm 1.0 1.0 Surface treatment No processing No processing In thin films Dosage PP-1 weight% 99.52 0.00 PP-2 weight% 0.00 36.00 PP-3 weight% 0.00 63.52 Masterbatch containing antiblocking agent weight% 0.48 0.48 Anti-adhesive content ppm 240 240 Film-forming conditions (refer to Table 3) a b

[0086] (OPP-1) The substrate layer (A) is made of polypropylene homopolymer PP-1 as shown in Table 1. The surface layer (B) is made by blending 96.4% by weight of polypropylene homopolymer PP-1 as shown in Table 1 and 3.6% by weight of masterbatch A as shown in Table 2. The surface layer (C) is made by blending 94.0% by weight of polypropylene homopolymer PP-1 as shown in Table 1 and 6.0% by weight of masterbatch A as shown in Table 2. The substrate layer (A) is extruded using a 45mm extruder, the surface layer (B) using a 25mm extruder, and the surface layer (C) using a 20mm extruder. The raw material resin is melted at 250°C and co-extruded into a sheet from a T-die. After cooling and curing by contacting a 30°C cooling roller with the surface layer (B), it is stretched 4.5 times in the longitudinal direction (MD) at 135°C. Next, in a tenter frame, the film is clamped at both ends along its width direction (TD) using a fixture. After preheating at 173°C, it is stretched 8.2 times in the width direction (TD) at 164°C, then softened by 6.7% in the width direction (TD), and simultaneously heat-fixed at 171°C. This film-forming condition is set as film-forming condition a. This yields a biaxially aligned polypropylene film consisting of a surface layer (B), a substrate layer (A), and a surface layer (C). The surface of the surface layer (B) of the biaxially aligned polypropylene film is corona-treated using a corona treatment machine manufactured by SOFTAL Corona & Plasma GmbH at a current of 0.75A, and then wound up using a winding machine. The resulting film has a thickness of 20 μm (the thicknesses of the surface layer (B), substrate layer (A), and surface layer (C) are 1.0 μm / 18.0 μm / 1.0 μm).

[0087] (OPP-2) The substrate layer (A) is made of 40.0% by weight of polypropylene homopolymer PP-2 as shown in Table 1 and 60.0% by weight of polypropylene homopolymer PP-3 as shown in Table 1. The surface layer (B) is made by blending 96.4% by weight of polypropylene homopolymer PP-3 as shown in Table 1 and 3.6% by weight of masterbatch A as shown in Table 2. The surface layer (C) is made by blending 94.0% by weight of polypropylene homopolymer PP-3 as shown in Table 1 and 6.0% by weight of masterbatch A as shown in Table 2. The substrate layer (A) was extruded using a 45mm extruder, the surface layer (B) using a 25mm extruder, and the surface layer (C) using a 20mm extruder. Each layer was extruded from melted raw resin at 250°C through a T-die into a sheet. After cooling and curing with the surface layer (B) in contact with a 30°C cooling roller, it was stretched 4.5 times in the longitudinal direction (MD) at 125°C. Next, in a tenter frame, the film was clamped at both ends in the width direction (TD) and preheated at 168°C. It was then stretched 8.2 times in the width direction (TD) at 155°C, with a reduction of 6.7% in the width direction (TD), and simultaneously heat-fixed at 165°C. These film-forming conditions are set as film-forming condition b. This yields a biaxially aligned polypropylene film composed of surface layer (B), substrate layer (A), and surface layer (C). The surface of the surface layer (B) of the biaxially aligned polypropylene film was corona treated using a corona treatment machine manufactured by SOFTAL Corona & Plasma GmbH at a current of 0.75 A, and then wound up using a winding machine. The resulting film has a thickness of 20 μm (the thicknesses of the surface layer (B) / substrate layer (A) / surface layer (C) are 1.0 μm / 18.0 μm / 1.0 μm).

[0088] [Preparation of Coating Layer] The following describes the method for preparing the coating layer used in each embodiment and comparative example. [Polyester Resin (A)] As the polyester component, a polyester polyol (DIC Corporation "DF-COAT GEC-004C": 30% solids) was used.

[0089] [Polyisocyanate crosslinking agent (B)] As a polyisocyanate component, a trimethylolpropane adduct of p-diisocyanate (Mitsui Chemicals Co., Ltd. "Takenate D-110N": solid content 75%) is used.

[0090] [Silane Coupling Agent (C)] As a silane coupling agent, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd. "KBM-603") is used.

[0091] [Aminocarbamate resin (D)] As the aminocarbamate resin, a dispersion of polyester aminocarbamate resin is used (DIC Corporation "Hydran (registered trademark) Ap-201"; solid content 23%).

[0092] [Aminocarbamate resin (E)] As the aminocarbamate resin, a dispersion of polyester aminocarbamate resin (Mitsui Chemicals Co., Ltd. "Takelac (registered trademark) WPB531"; solid content 30%) is used.

[0093] [Coating Solution 1] A solution of silane coupling agent (C) dissolved in acetone (15% by mass) 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 further added to obtain the desired coating solution 1. The mixing ratios are shown below. Polyester resin (A) 10.62% by mass Isocyanate (B) 4.07% by mass Silane coupling agent (C) ※Acetone diluent 1.73% by mass Methyl ethyl ketone 69.55% by mass PGM 14.03% by mass

[0094] [Coating Solution 2] Prepare coating solution 2 by mixing the following coating agents: Water 43.91% by mass, Isopropanol 30.00% by mass, Carbamate resin (D) 26.09% by mass.

[0095] [Coating Solution 3] Prepare coating solution 3 by mixing the following coating agents: Water 46.00% by mass, Isopropanol 30.00% by mass, Carbamate resin (E) 24.00% by mass.

[0096] [Preparation of laminated films] (Examples 1 and 2) The substrate film was OPP-1, and the coating layer was coated with coating liquid 1. The coating was applied to the corona-treated surface of the substrate film using a gravure roller coating method and dried in a drying oven at 130°C for 10 seconds. The coating layer adhesion amount at this time was 0.40 g / m². Afterwards, a post-heat treatment at 40°C for 2 days was applied to obtain the desired laminated film. (Example 3) The desired laminated film was obtained under the same conditions as in Example 1, except that coating liquid 2 was used as the coating layer. (Example 4) The desired laminated film was obtained under the same conditions as in Example 1, except that the coating layer adhesion amount was changed to 0.25 g / m². (Example 5) The desired laminated film was obtained under the same conditions as in Example 1, except that the drying temperature was changed to 110°C. (Example 6) The desired laminated film was obtained under the same conditions as in Example 1, except that the drying temperature was changed to 150°C.

[0097] (Comparative Example 1) The same substrate film as in Example 1 was used, but no coating layer was deposited. (Comparative Example 2) The desired laminated film was obtained under the same conditions as in Example 1, except that coating liquid 3 was used as the coating layer. (Comparative Example 3) The desired laminated film was obtained under the same conditions as in Example 1, except that OPP-2 was used as the substrate film.

[0098] [Formation of Inorganic Thin Film Layer] The following describes the methods for fabricating the inorganic thin film layer used in each embodiment and comparative example. (M-1; Example 1, Comparative Example 1) As the inorganic thin film layer M-1, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the coating layer by electron beam evaporation. For the evaporation source, particle-shaped SiO2 (99.9% purity) and Al2O3 (99.9% purity) of approximately 3 mm to 5 mm were used. The thickness of the inorganic thin film layer (SiO2 / Al2O3 composite oxide layer) in the resulting thin film (inorganic thin film layer / thin film containing the coating layer) was 13 nm. Furthermore, the composition of this composite oxide layer was SiO2 / Al2O3 (mass ratio) = 60 / 40.

[0099] (M-2; Examples 2-6, Comparative Examples 2-3) As the inorganic thin film layer M-2, metallic aluminum was deposited on the coating layer. Using a small vacuum evaporation apparatus (ULVAC Machinery Co., Ltd., VWR-400 / ERH), after reducing the pressure to below 10-3 Pa, aluminum foil with a purity of 99.9% was placed from the bottom of the substrate onto a Nirako CF-305W evaporation source, and the metallic aluminum was heated and evaporated to form a metallic aluminum film with a thickness of 40 nm on the thin film.

[0100] The results of various evaluations performed on the laminated film obtained as described above are shown in Table 5.

[0101] [Table 5A] unit Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Substrate film type - OPP-1 OPP-1 OPP-1 OPP-1 OPP-1 OPP-1 Cover layer Coating liquid none - 1 - ● ● ● ● ● 2 - ● 3 - Coating conditions Drying temperature ℃ 130 130 130 130 110 150 Drying time Second 10 10 10 10 10 10 Adhesion amount g / m 2 0.40 0.40 0.40 0.25 0.40 0.40 Appearance Visual evaluation - ○ ○ ○ ○ ○ ○ Elongation at 100℃ MD direction % 1.7 1.7 1.8 1.9 2.3 1.7 TD direction % 1.4 1.4 1.0 1.3 1.0 0.9 Elongation at heating 130℃ MD direction % 4.9 4.9 4.5 5.4 6.4 4.2 TD direction % 3.9 3.9 3.1 3.5 3.0 2.6 Surface roughness Rp nm 1.6 1.6 4.2 1.6 0.9 2.8 Rv nm 1.4 1.4 2.7 1.6 0.9 2.3 (Rp+Rv) nm 3.0 3.0 6.8 3.2 1.7 5.1 IR peak 1720±10cm -1 (P1) - 0.02 0.02 0.05 0.01 0.02 0.03 1070±10cm -1 (P2) - 0.06 0.06 0.11 0.03 0.06 0.06 (P2 / P1) - 2.3 2.3 2.2 5.1 2.5 2.4 Inorganic thin film layer type - M-1 M-2 M-2 M-2 M-2 M-2 thickness nm 20 40 40 40 40 40 Oxygen penetration cc / m 2 . day. atm 1.7 4.5 5.3 4.9 4.6 6.2 Water vapor penetration g / m 2 day 1.0 0.3 0.8 0.4 0.4 0.3

[0102] [Table 5B] unit Comparative Example 1 Comparative Example 2 Comparative Example 3 Substrate film type - OPP-1 OPP-1 OPP-2 Cover layer Coating liquid none - ● 1 - ● 2 - 3 - ● Coating conditions Drying temperature ℃ - 130 130 Drying time Second - 10 10 Adhesion amount g / m 2 - 0.40 0.40 Appearance Visual evaluation - ○ ○ × Elongation at 100℃ MD direction % 1.8 1.5 3.4 TD direction % 1.4 1.3 1.5 Elongation at heating 130℃ MD direction % 4.5 4.1 10.7 TD direction % 3.4 4.4 4.6 Surface roughness Rp nm 21.3 20.0 1.5 Rv nm 22.4 16.6 1.4 (Rp+Rv) nm 43.7 36.7 2.9 IR peak 1720±10cm -1 (P1) - 0.00 0.01 0.02 1070±10cm -1 (P2) - 0.00 0.06 0.05 (P2 / P1) - -1.4 4.1 3.0 Inorganic thin film layer type - M-1 M-2 M-2 thickness nm 20 40 40 Oxygen penetration cc / m 2 . day. atm 99.6 15.6 10.2 Water vapor penetration g / m 2 day 3.7 0.6 0.8 [Potential for industrial application]

[0103] According to the present invention, it becomes possible to provide a laminated film that is capable of forming a film composed of a single resin species with low environmental impact, mainly composed of polypropylene film, while having gas barrier properties required for packaging materials when laminating inorganic film layers. [Simplified Explanation of the Diagram]

[0016] None.

Claims

1. A laminated film for forming an inorganic thin film layer, comprising a laminated coating layer on at least one side of a substrate layer mainly composed of a polypropylene resin, characterized in that, in the total reflectance infrared absorption spectrum measured from the coating layer side of the laminated film, the ratio (P2 / P1) of the peak intensity (P1) with maximum absorption in the region of 1720±10 cm⁻¹ and the peak intensity (P2) with maximum absorption in the region of 1070±10 cm⁻¹ is in the range of 0.1 to 30.0, and the laminated film satisfies the following requirements (I) to (III): (I) The elongation at 130°C of the laminated film is 10% or less in both the MD direction and the TD direction; (II) The sum of the maximum peak height (Rp) and the maximum valley depth (Rv) on the coating layer side surface, as measured by a scanning probe microscope, is 30.0 nm or less. (III) The amount of coating attached is above 0.10 g / m2 and below 0.50 g / m2.

2. The laminated film for forming an inorganic thin film layer as claimed in claim 1, wherein the elongation at 100°C is less than 3% in both the MD direction and the TD direction.

3. A laminated film, characterized in that a laminated inorganic film layer is present on the coating layer of the laminated film as claimed in claim 1 or 2.

4. The laminated thin film as claimed in claim 3, wherein the inorganic thin film layer contains Al and / or Si.