Multilayer film for forming inorganic thin film layer, and multilayer body

Abstract

The purpose of the present invention is to provide a multilayer film which is capable of forming a laminate structure that is mainly composed of a polypropylene film and is composed of almost a single resin type that has a small environmental load, and which is excellent in terms of gas barrier properties even after a retort treatment when inorganic thin film layers are laminated, and can exhibit good adhesion.　The present invention relates to a multilayer film for forming an inorganic thin film layer, the multilayer film being obtained by superposing a coating layer on at least one surface of a base material layer that is mainly composed of a polypropylene resin, and being characterized by satisfying the requirements (I) to (III) described below. (I) The contact angle value of ethylene glycol on the surface of the coating layer of the multilayer film is 42-47°. (II) The contact angle value of water on the surface of the coating layer of the multilayer film is 60° or more. (III) The adhesion amount of the coating layer is 1.40 g / m2 or more.

Description

Laminated film and laminate for forming inorganic thin film layer

[0001] The present invention relates to a laminate film and a laminate body used in the packaging fields of foods, medicines, industrial products, etc. More specifically, the present invention relates to a gas barrier laminate film and a laminate body that can exhibit excellent gas barrier properties and adhesion (lamination strength) when made from easily recyclable materials and provided with an inorganic thin film layer.

[0002] In recent years, regulations aimed at reducing the use of disposable plastics have been strengthened in Europe and other countries around the world. Behind these trends are growing international awareness of resource recycling and the worsening waste problems in emerging countries. Therefore, environmentally friendly products are being sought from the perspective of the 3Rs (Recycle, Reuse, Reduce) for plastic packaging materials required for food, pharmaceuticals, etc.

[0003] The performance requirements for the aforementioned environmentally friendly packaging materials include (1) being made from materials that are easy to recycle, (2) having gas barrier properties (particularly gas barrier properties for retort applications) that can block various gases and extend the shelf life, and (3) having a laminate structure that places a low burden on the environment (for example, being recyclable by converting it into a monomaterial).

[0004] In recent years, the use of polypropylene films has attracted attention in order to achieve the above (1) and (3). Polypropylene films are widely used in a wide range of applications, including packaging for food and various other products, electrical insulation, and surface protection films. Due to their molecular structure, polypropylene films are capable of exhibiting high water vapor barrier properties. Furthermore, since polypropylene- or polyethylene-based heat seal resins are generally used as sealants to be bonded to surface substrate films, for example, by using a polypropylene film as the surface substrate and an unstretched polypropylene sheet as the sealant, a mono-material packaging material can be achieved as a whole while maintaining gas barrier properties, enabling the design of environmentally friendly packaging materials that are easy to recycle, etc.

[0005] However, with regard to the gas barrier property (2) above, although polypropylene films have water vapor barrier properties, they have poor oxygen barrier properties, which are significantly worse than, for example, transparent inorganic vapor-deposited polyester films, which are generally considered to have excellent oxygen barrier properties.Furthermore, there is also the problem that the gas barrier properties required for retort pouch applications are insufficient.

[0006] In contrast to this, gas barrier laminates are generally used in which a thin metal film made of aluminum or the like, or a thin inorganic film made of an inorganic oxide such as silicon oxide or aluminum oxide, is formed on the surface of a plastic substrate film such as a polyester film. Among these, those in which a thin film of an inorganic oxide such as silicon oxide, aluminum oxide, or a mixture thereof is formed are widely used because they do not require the use of aluminum foil, are transparent so that the contents can be visualized, and furthermore, the formed film is very thin and does not hinder recyclability.

[0007] A method has also been disclosed for imparting gas barrier properties to polypropylene films by laminating an inorganic thin film (e.g., Patent Document 1). However, the surface of the polypropylene film is highly uneven due to its molecular structure, and there are many cracks in the inorganic thin film layer, which makes it difficult to achieve 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 thin film layer to smooth the surface on which the inorganic thin film layer is formed, thereby imparting gas barrier properties (e.g., Patent Document 2). However, when a polyvinyl alcohol polymer resin composition is used, the oxygen barrier properties decrease under high humidity conditions due to its high humidity dependency, and the water vapor barrier properties are also insufficient.

[0009] To address the problem of reduced oxygen barrier properties under high humidity, a method has been disclosed in which a polymer resin composition containing a mixture of polyurethane, whose components are polyester and isocyanate, and a silicon-based crosslinking agent is used between a polypropylene film and an inorganic thin film layer, thereby imparting good oxygen barrier properties and water-resistant adhesion under high humidity (e.g., Patent Document 3). However, there was still the problem of not being able to achieve sufficient gas barrier properties.

[0010] International Publication No. 2017 / 221781 Japanese Patent Application Laid-Open No. 2021-20392 Japanese Patent Application Laid-Open No. 2023-67401

[0011] As described above, the gas barrier performance under high humidity conditions was insufficient in the above Patent Documents 1 to 3. In other words, there has not been a material that satisfies all three of the performance requirements for the environmentally friendly packaging material: (1) containing a recyclable material as a constituent material, (2) having gas barrier performance (particularly gas barrier performance for retort pouch applications) that can block various gases and extend the shelf life, and (3) having a laminate structure that is easy to recycle and has a low environmental impact (mono-material).

[0012] The present invention was made in response to the problems of the prior art. Specifically, an object of the present invention is to provide a laminate film and a laminate body including the laminate film, which can form a laminate structure composed of almost a single resin type, primarily a polypropylene film, with low environmental impact, and which, when laminated with an inorganic thin film layer, exhibits excellent gas barrier properties and good adhesion even after retort treatment. In a more preferred embodiment, the present invention aims to provide a laminate film that also exhibits excellent gas barrier properties when an inorganic thin film layer is formed. In a further preferred embodiment, the present invention aims to provide a laminate film that exhibits excellent gas barrier properties both before and after the formation of the inorganic thin film layer.

[0013] The present inventors have discovered that, with regard to a coating layer provided between a plastic substrate film and an inorganic thin film layer, in addition to imparting gas barrier properties to the coating layer itself, further improving the gas barrier properties can be achieved by hydrophilizing the surface of the coating layer and depositing the inorganic thin film layer uniformly and densely. Furthermore, the present inventors have discovered that hydrophilicity and water resistance can be imparted to the coating layer by adjusting the ethylene glycol contact angle and water contact angle of the coating layer to fall within a predetermined range. As one aspect of this, the inventors have discovered that the improved gas barrier properties can be maintained even after retort treatment by appropriately crosslinking the hydrophilic component, isocyanate curing agent, and silicon-based crosslinking agent in the coating layer, and thus have completed the present invention.

[0014] That is, the present invention has the following configuration. 1. A laminate film for forming an inorganic thin film layer, comprising a base layer mainly composed of a polypropylene-based resin and a coating layer laminated on at least one surface of the base layer, wherein the laminate film satisfies the following requirements (I) to (III): (I) The contact angle of ethylene glycol on the surface of the coating layer of the laminate film is 42 to 47°. (II) The contact angle of water on the surface of the coating layer of the laminate film is 60° or more. (III) The coating layer has a coating weight of 1.40 g / m 2 2. The oxygen permeability of the laminated film is 6,500 ml / m or more. 2The laminate film according to 1. above, wherein the coating layer contains a polyester resin having an acid value of 5 mgKOH / g or more per day. 3. The laminate film according to 1. or 2. above, wherein the coating layer further contains a polyurethane resin. 5. The laminate film according to 3. or 4. above, wherein the content of the polyester resin constituting the coating layer with an acid value of 5 mgKOH / g or more is 10 to 65 mass % relative to 100 mass % of the solid content of the composition constituting the coating layer. 6. The laminate film according to any of 1. to 5. above, wherein an inorganic thin film layer is laminated on the coating layer of the laminate film. 7. The laminate film according to 6. above, wherein the inorganic thin film layer is composed of one or more materials selected from aluminum, silicon oxide, aluminum oxide, and a mixture of silicon oxide and aluminum oxide. 8. The laminate film having the inorganic thin film layer laminated thereon has an oxygen permeability of 1 to 25 ml / m under conditions of 23°C x 65% RH. 2 9. A laminated body obtained by laminating a polyolefin sealant layer on one side of the laminated film according to any one of 1. to 8. 10. A laminated body obtained by subjecting the laminated body to a retort treatment and having an oxygen permeability of 50 ml / m 2 11. The laminate according to 9. above, wherein the laminate strength after retort treatment is 1.0 N / 15 mm or more. 12. Use of the laminate film according to any one of 1. to 8. above for forming an inorganic thin film layer.

[0015] According to the present invention, a film can be formed into a laminate structure composed of almost a single resin type, mainly a polypropylene film, which has a low environmental impact, and when an inorganic thin film layer is laminated thereon, the film can exhibit excellent gas barrier properties and good adhesion even after retort treatment. According to a more preferred embodiment of the present invention, a laminate film can be provided that also exhibits excellent gas barrier properties when an inorganic thin film layer is formed. According to an even more preferred embodiment of the present invention, a laminate film can be provided that exhibits excellent gas barrier properties both before and after the formation of the inorganic thin film layer.

[0016] The present invention will be described in detail below. The laminate film for forming an inorganic thin film layer of the present invention is a laminate film having a coating layer laminated on at least one surface of a base layer mainly composed of a polypropylene-based resin, and is characterized in that the laminate film satisfies the following requirements (I) to (III): (I) The contact angle of ethylene glycol on the surface of the coating layer of the laminate film is 42 to 47°. (II) The contact angle of water on the surface of the coating layer of the laminate film is 60° or more. (III) The coating layer has a coating weight of 1.40 g / m 2 That's all.

[0017] In the present invention, the laminate film for forming an inorganic thin film layer comprises a base layer and a coating layer, and a laminate film having an inorganic thin film layer formed on the coating layer is sometimes referred to as an inorganic thin film layer-containing laminate film, a laminate film having a sealant layer formed on the inorganic thin film layer via an adhesive is sometimes referred to as a laminate laminate, and a laminate film that has been retorted is sometimes referred to as a laminate laminate after retort treatment. Each layer of the laminate film will be described below.

[0018] [Substrate Layer (Substrate Film)] The laminate film of the present invention includes a substrate layer primarily composed of a polypropylene-based resin. The substrate layer is preferably a polypropylene-based film primarily composed of a polypropylene-based resin, and more preferably a stretched polypropylene-based film. The stretched polypropylene-based film used as the substrate layer in the present invention may be a film stretched in at least one direction, and is preferably a biaxially stretched film. Known biaxially stretched polypropylene-based films can be used as biaxially stretched polypropylene-based films, and their raw materials and blend ratios are not particularly limited. The polypropylene-based resin may be, for example, a polypropylene homopolymer (propylene homopolymer), a propylene copolymer (preferably a propylene random copolymer or a propylene block copolymer) containing propylene as the primary component with one or more α-olefins selected from ethylene, butene, pentene, hexene, and the like, or a mixture of two or more of these polymers. The propylene homopolymer and the propylene copolymer may each be used singly or in combination of two or more. For the purpose of improving physical properties, known additives such as antioxidants, antistatic agents, plasticizers, etc. may be added, and for example, petroleum resins, terpene resins, etc. may be added.

[0019] In the present invention, the polypropylene-based resin constituting the base film is preferably a propylene homopolymer substantially free of comonomers (preferably ethylene, propylene, or butene), and the comonomer amount is preferably 0 mol % to 0.5 mol %, more preferably 0 mol % to 0.3 mol %, and even more preferably 0 mol % to 0.1 mol %. Within the above range, crystallinity is improved, dimensional change at high temperatures is reduced, i.e., the elongation when heated to a certain temperature (hereinafter referred to as "heat elongation") is reduced, and heat resistance is improved. Note that a trace amount of comonomer may be contained within a range that does not significantly reduce crystallinity.

[0020] The polypropylene-based resin constituting the base film preferably contains a propylene homopolymer obtained only from propylene monomers, and even if it is a propylene homopolymer, it is most preferable that it does not contain heterogeneous bonds such as head-to-head bonds.

[0021] From a practical standpoint, the xylene soluble content of the polypropylene resin constituting the base film is preferably 0.1 to 7 mass%, more preferably 0.1 to 6 mass%, and even more preferably 0.1 to 5 mass%. Within this range, crystallinity is improved, the thermal elongation rate is further reduced, and heat resistance is improved.

[0022] The base film preferably contains, as the polypropylene-based resin, a propylene homopolymer having a mesopentad fraction of 96% or more. The mesopentad fraction of the propylene homopolymer is more preferably 97 to 99.9%, even more preferably 97.5 to 99.9%, and even more preferably 98 to 99.9%. When the mesopentad fraction is within the above range, the crystallinity of the polypropylene resin is high, and a base film having predetermined rigidity and heat resistance can be obtained. When the mesopentad fraction is less than 96%, wrinkles may form in part of the packaging material, deteriorating the appearance of the seal.

[0023] The mesopentad fraction is calculated according to the method described in Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973), for example. 13 It can be measured using C-NMR. 13 As a condition for C-NMR measurement, for example, an AVANCE 500 manufactured by BRUKER is used, and 200 mg of a sample is dissolved in a mixed solution of o-dichlorobenzene and deuterated benzene at a ratio of 8:2 at 135°C, and measurement is performed at 110°C.

[0024] In the present invention, the melt flow rate (MFR) (230°C, 2.16 kgf) of the polypropylene resin is preferably 0.5 g / 10 min to 20 g / 10 min, more preferably 1.0 g / 10 min to 17 g / 10 min, even more preferably 2.0 g / 10 min to 16 g / 10 min, and even more preferably 4.0 g / 10 min to 15 g / 10 min. Within the above range, the mechanical load is small, and extrusion and stretching are easy. Furthermore, within the above range, stretching is easy, thickness unevenness is reduced, and the stretching temperature and heat setting temperature can be easily increased, resulting in a smaller heat elongation and improved heat resistance.

[0025] The polypropylene resin may have a predetermined mass average molecular weight Mw, and the mass average molecular weight Mw of the polypropylene resin is preferably 200,000 to 500,000, more preferably 210,000 to 450,000, and even more preferably 220,000 to 400,000. When the mass average molecular weight is within the above range, the stretching temperature can be increased, which tends to facilitate stretching.

[0026] The polypropylene resin may have a predetermined number-average molecular weight Mn, and the number-average molecular weight of the polypropylene resin is preferably 30,000 to 100,000, more preferably 40,000 to 90,000, and even more preferably 50,000 to 85,000. When the number-average molecular weight is within the above range, the stretching temperature can be increased, and stretching tends to be easier.

[0027] The molecular weight distribution (mass average molecular weight / number average molecular weight) of the polypropylene resin is preferably 2 to 10, more preferably 2.2 to 9, even more preferably 2.4 to 8, and even more preferably 2.6 to 7. When the polypropylene resin has a molecular weight distribution within the above range, a low molecular weight polypropylene resin and a high molecular weight polypropylene resin are contained in a balanced manner, and a film with high crystallinity can be obtained. The mass average molecular weight, number average molecular weight, and molecular weight distribution of the polypropylene resin are calculated using gel permeation chromatography (GPC).

[0028] The polypropylene-based resin may have a predetermined DSC melting peak temperature, and the DSC melting peak temperature of the polypropylene-based resin is, for example, 120 to 180° C., preferably 122 to 175° C., more preferably 124 to 173° C., even more preferably 125 to 170° C., and still more preferably 125 to 169° C. When the polypropylene-based resin has a DSC melting peak temperature in the above range, heat sealing at high temperatures becomes possible.

[0029] The polypropylene-based resin may have a predetermined DSC melting peak area, and the DSC melting peak area of ​​the polypropylene-based resin is, for example, 50 to 130 J / g, preferably 55 to 120 J / g, and more preferably 60 to 110 J / g. When the polypropylene-based resin has a DSC melting peak area within the above range, a substrate film with a high degree of crystallinity can be obtained. Both the DSC melting peak temperature and the DSC melting peak area are calculated according to the method described in the Examples below.

[0030] From the viewpoint of film rigidity, the content of the polypropylene resin constituting the base film is preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, still more preferably 95 to 100 mass%, and particularly preferably 99 to 100 mass%, relative to 100 mass% of the resin composition constituting the base film.

[0031] The content of the propylene homopolymer having a mesopentad fraction of 96% or more is preferably 40 to 100% by mass, more preferably 60 to 100% by mass, even more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass, relative to 100% by mass of the resin composition constituting the substrate film. When the substrate film has multiple layers, it is sufficient that any one or each of the multiple layers satisfies the above range.

[0032] The substrate film (preferably a biaxially oriented polypropylene resin film) used in the present invention may be a single layer or a multi-layer structure in which multiple resin films, including a biaxially oriented polypropylene resin film, are laminated. When a multi-layer structure is used, the type, number of layers, and lamination method are not particularly limited and can be arbitrarily selected from known methods depending on the purpose. Examples of the substrate film configuration include surface layer / substrate layer, surface layer / substrate layer / surface layer, and surface layer / substrate layer / substrate layer / surface layer. An adhesive layer may be provided between the surface layer and the substrate layer, but it is preferable not to provide an adhesive layer from the viewpoint of productivity, etc. Furthermore, when a surface layer is provided, the surface of the substrate layer may be subjected to a surface treatment such as a corona treatment or a heat treatment to improve adhesion. In particular, the substrate film may be composed of a substrate layer and a surface layer, and one or more surface layers may be provided. The substrate film preferably has a surface layer / substrate layer / surface layer configuration.

[0033] The surface layer and the base layer preferably contain at least a propylene homopolymer, and may contain multiple propylene homopolymers or a propylene homopolymer and a propylene copolymer. The base layer preferably contains 70 to 100 mass%, more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass% of a propylene homopolymer having a mesopentad fraction of 96% or more. The surface layer preferably contains 70 to 100 mass%, more preferably 80 to 100 mass%, and even more preferably 90 to 100 mass% of a propylene homopolymer having a mesopentad fraction of 96% or more. The surface layer may contain a propylene copolymer and a propylene homopolymer having a mesopentad fraction of 96% or more, and preferably contains 20 to 70% by mass, more preferably 30 to 60% by mass, and even more preferably 40 to 50% by mass of the propylene homopolymer having a mesopentad fraction of 96% or more, and preferably contains 30 to 80% by mass, more preferably 40 to 70% by mass, and even more preferably 50 to 60% by mass of the propylene copolymer. In the surface layer / base layer / surface layer configuration, the surface layers may have the same configuration or different configurations, and different configurations are preferred.

[0034] From the viewpoint of heat resistance, the substrate film may be a uniaxially stretched film in the machine direction or longitudinal direction (MD direction) or the transverse direction or width direction (TD direction), but is preferably a biaxially stretched film. In the present invention, by stretching at least uniaxially, a film having a low heat shrinkage rate at high temperatures and high heat resistance, which was not expected with conventional polypropylene films, can be obtained. Examples of stretching methods include simultaneous biaxial stretching and sequential biaxial stretching, but sequential biaxial stretching is preferred from the viewpoint of improving flatness, dimensional stability, thickness unevenness, etc.

[0035] In the sequential biaxial stretching method, a polypropylene resin is heated and melted in a single-screw or twin-screw extruder so that the resin temperature is preferably 200 to 280°C (more preferably 210 to 270°C, and even more preferably 220 to 260°C), formed into a sheet from a T-die, and extruded onto a chill roll having a temperature of preferably 10 to 100°C (more preferably 20 to 80°C, and even more preferably 25 to 60°C) to obtain an unstretched sheet. Next, the film is roll-stretched in the machine direction (MD direction) preferably at 120 to 165°C (more preferably 120 to 150°C, even more preferably 120 to 140°C) and preferably 3.0 to 8.0 times (more preferably 3.5 to 7.0 times, even more preferably 4.0 to 6.5 times), and subsequently, after preheating in a tenter, it can be stretched in the transverse direction (TD direction) preferably at 155 to 175°C (more preferably 157 to 173°C, even more preferably 159 to 171°C) and preferably 4.0 to 20.0 times (more preferably 5.0 to 15 times, even more preferably 6.0 to 14 times, even more preferably 7.0 to 10 times). Furthermore, after biaxial stretching, it can be heat-set at a temperature of preferably 165 to 175°C (more preferably 165 to 172°C), preferably while allowing relaxation of 1 to 15% (more preferably 2 to 12%, even more preferably 3 to 10%).

[0036] In order to impart handleability (e.g., windability after lamination) to the substrate film used in the present invention, it is preferable to incorporate particles into the film (preferably the surface layer) to form protrusions on the film surface. Examples of particles to be incorporated into the film (preferably the surface layer) include inorganic particles such as silica, kaolinite, talc, calcium carbonate, zeolite, and alumina, and heat-resistant polymer particles such as acrylic, PMMA, nylon, polystyrene, polyester, and benzoguanamine-formalin condensates. Among these, inorganic particles are preferred, and silica is more preferred. From the viewpoint of transparency, the particle content in the film is preferably low, and is preferably, for example, 1 ppm to 4000 ppm, and more preferably 50 ppm to 3500 ppm, relative to the total mass of the film (preferably the surface layer). The average particle size of the particles is preferably 1.0 to 3.0 μm, and more preferably 1.0 to 2.7 μm. The average particle size here is measured by taking a photograph with a scanning electron microscope, measuring the Feret's diameter in the horizontal direction using an image analyzer, and expressing it as the average value. Furthermore, from the viewpoint of transparency, it is preferable to select particles having a refractive index close to that of the resin used. Furthermore, the base film may contain antioxidants, ultraviolet absorbers, antistatic agents, dyes, lubricants, nucleating agents, adhesives, antifogging agents, flame retardants, antiblocking agents, inorganic or organic fillers, etc. to impart various functions as needed.

[0037] In addition to the polypropylene resin used in the present invention, other resins can be used to improve the mechanical properties of the base film and the adhesion to an ink layer or adhesive layer laminated on the gas barrier coating layer, as long as the object of the present invention is not impaired. Examples of such resins include polypropylene resins other than those mentioned above, random copolymers which are copolymers of propylene with ethylene and / or an α-olefin having 4 to 10 carbon atoms, and various elastomers.

[0038] In the present invention, the thickness of the substrate film is set arbitrarily according to the application, but is preferably 2 to 300 μm, more preferably 3 to 250 μm, even more preferably 4 to 200 μm, even more preferably 5 to 100 μm, and particularly preferably 10 to 100 μm. A thin thickness tends to result in poor handling. On the other hand, a thick thickness not only creates cost problems, but also makes it more likely to suffer from poor flatness due to curling when wound into a roll and stored. When the substrate film includes a surface layer and a substrate layer, the total thickness of the surface layer and the substrate layer should be within the above range. The thickness of the substrate layer is, for example, 2 to 40 μm, preferably 3 to 35 μm, more preferably 4 to 30 μm, and even more preferably 5 to 25 μm. The thickness of the surface layer is, for example, 0.5 to 10 μm, preferably 0.7 to 7 μm, and more preferably 0.9 to 5 μm.

[0039] The substrate film of the present invention preferably has transparency from the viewpoint of visibility of contents, and the haze of the substrate film is specifically preferably 0.1 to 6%, more preferably 0.5 to 5%, and even more preferably 1 to 4%. Haze tends to deteriorate, for example, when the stretching temperature or heat setting temperature is too high, when the cooling roll (CR) temperature is high and the cooling rate of the stretched raw sheet is slow, or when there is too much low molecular weight, so it can be controlled within the above range by adjusting these.

[0040] Furthermore, the substrate film in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, or surface roughening treatment, and may also be subjected to known anchor coating treatment, printing, decoration, etc., as long as the object of the present invention is not impaired.

[0041] [Coating Layer] The laminate film of the present invention has a coating layer to ensure sufficient gas barrier properties when laminated with an inorganic thin film layer. The coating layer can suppress the release of oligomers and antiblocking agents from the polypropylene-based resin. Furthermore, it can also enhance interlayer adhesion when laminating other layers on the coating layer. In particular, when forming an inorganic thin film layer, not only is adhesion important, but protrusions due to surface irregularities can also prevent thin film formation, resulting in poor gas barrier properties. Additionally, using a gas barrier material for the coating layer itself can significantly improve the gas barrier performance of the laminate film. Furthermore, the coating layer prevents hot water from penetrating the substrate, thereby reducing film whitening after boiling or retorting.

[0042] In the present invention, the coating amount of the coating layer is 1.40 g / m 2 or more, and preferably 1.40 to 2.50 g / m 2 , more preferably 1.45 to 2.30 g / m 2 , more preferably 1.50 to 2.10 g / m 2 This allows the coating layer to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. Furthermore, the coating layer contributes to suppressing oligomer exposure, stabilizing haze after retorting. The coating layer deposition amount is 2.50 g / m 2 If the coating layer thickness exceeds 1.40 g / m, the gas barrier property is improved, but in terms of processability, the thick film thickness may cause blocking or increase the manufacturing cost. Furthermore, there is a concern that the recyclability of the film may be adversely affected. On the other hand, if the coating layer thickness exceeds 1.40 g / m, 2 If it is less than this, sufficient gas barrier properties may not be obtained.

[0043] Resin compositions used in the coating layer of the present invention include those containing urethane-based, polyester-based, acrylic-based, imine-based, polybutadiene-based, or other resins to which titanium-based, epoxy-based, isocyanate-based, melamine-based, or other curing agents have been added. Crosslinking agents such as silicon-based crosslinkers, oxazoline compounds, carbodiimide compounds, and epoxy compounds may also be included. In addition, high-acid-value polyester-based, urethane-based, acrylic-based, and vinyl alcohol-based resins may also be mixed. In particular, urethane resins not only offer barrier performance due to the high cohesiveness of the urethane bond itself, but also exhibit flexibility due to the presence of amorphous portions, thereby reducing damage even when subjected to bending loads. Similar effects can also be expected from polyester resins. Furthermore, high-acid-value polyester resins can improve gas barrier properties due to the highly polar functional groups modified on the polyester resin that strongly interact with the inorganic thin film layer. In the present invention, it is preferable to contain (1) a polyurethane resin or a polyurethane resin containing (3) a polyester resin and (4) a polyisocyanate-based curing agent as constituent components, as described below. Furthermore, from the viewpoint of improving adhesion, it is more preferable to add (2) a crosslinking agent, and even more preferable to add a silicon-based crosslinking agent. In addition, it is preferable to mix (5) a high-acid-value polyester resin. In this way, it is particularly preferable that the coating layer contains (5) a high-acid-value polyester resin described below and further contains a polyurethane resin.

[0044] (1) Polyurethane Resin From the viewpoint of improving gas barrier properties, the polyurethane resin used in the present invention is preferably a polyurethane resin containing an aromatic or araliphatic diisocyanate component as a main constituent. Among these, it is particularly preferable that the polyurethane resin contains a metaxylylene diisocyanate component. By using such a resin, the cohesive strength of the urethane bond can be further increased due to the stacking effect between aromatic rings, resulting in good gas barrier properties.

[0045] (2) Crosslinking Agents The polyurethane resin used in the present invention may contain various crosslinking agents to improve the cohesive strength and heat- and moisture-resistant adhesion 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, and epoxy compounds. Among these, silicon-based crosslinking agents are particularly preferred from the viewpoint of improving water-resistant adhesion to the inorganic thin film layer. Examples of silicon-based crosslinking agents include metal alkoxides and silane coupling agents. Metal alkoxides are compounds represented by the general formula M(OR) n (M: metals such as Si and Al, R: CH ３ , C ２ H ５ and n is 1 to 4). Specifically, tetraethoxysilane [Si(OC ２ H ５ ) ４ ], triisopropoxyaluminum Al[OCH(CH ３ ) ２ ]3, etc. Examples of silane coupling agents include those having an epoxy group, such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane; those having an amino group, such as 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; those having a mercapto group, such as 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane; those having an isocyanate group, such as 3-isocyanatepropyltriethoxysilane; and tris-(3-trimethoxysilylpropyl)isocyanurate. Among these, it is preferable that the silicon-based crosslinking agent contains a silane coupling agent having an amino group. Other crosslinking agents that may be used in combination include oxazoline compounds, carbodiimide compounds, epoxy compounds, etc.

[0046] The silicon-based crosslinking agent is preferably added in an amount of 0.05 to 4.00% by mass to the composition constituting the coating layer, more preferably 0.10 to 3.50% by mass, and even more preferably 0.13 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 of crosslinking agent added exceeds 4.00% by mass, the film hardens and improves cohesive strength, but some unreacted portions may remain, potentially reducing interlayer adhesion. On the other hand, if the amount of crosslinking agent added is less than 0.05% by mass, sufficient cohesive strength may not be obtained.

[0047] (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 preferably 1,000 to 50,000, and more preferably 1,500 to 30,000. The functional group at the polyester end is also not particularly limited; 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 in which the alcohol end is the main component.

[0048] The Tg of the polyester used in the present invention is preferably 10°C or higher. If the temperature is lower than this, the resin will become tacky after the coating operation, making blocking more likely to occur and making the winding operation after coating more difficult. If the Tg is less than 10°C, 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 is more preferably 15°C to 70°C, and even more preferably 20°C to 60°C.

[0049] [Polycarboxylic Acid Component] The polycarboxylic acid component of the polyester resin used in the present invention preferably contains at least one ortho-oriented aromatic dicarboxylic acid or its anhydride. Ortho-orientation improves solubility in solvents, enabling uniform coating on the substrate. A uniformly coated coating layer reduces variation in barrier performance, thereby contributing to the suppression of whitening caused by oligomers. Furthermore, ortho-orientation results in a film with excellent flexibility and improved interfacial adhesion, thereby reducing damage to the substrate due to wet heat treatment and leading to the suppression of oligomers. Examples of aromatic polycarboxylic acids or anhydrides with carboxylic acids substituted at the ortho positions include orthophthalic acid or its anhydride, naphthalene 2,3-dicarboxylic acid or its anhydride, naphthalene 1,2-dicarboxylic acid or its anhydride, anthraquinone 2,3-dicarboxylic acid or its anhydride, and 2,3-anthracenecarboxylic acid or its anhydride. These compounds may have a substituent on any carbon atom of the aromatic ring. Examples of the substituent include a chloro group, a bromo group, a methyl group, an ethyl group, an i-propyl group, a hydroxyl group, a methoxy group, an ethoxy group, a phenoxy group, a methylthio group, a phenylthio group, a cyano group, a nitro group, an amino group, a phthalimide group, a carboxyl group, a carbamoyl group, an N-ethylcarbamoyl group, a phenyl group, or a naphthyl group. Furthermore, polyester polyols having a content of these in an amount of 70 to 100 mol % relative to 100 mol % of the total polycarboxylic acid components are particularly preferred because they have a high effect of improving barrier properties and excellent solvent solubility, which is essential for a coating material.

[0050] In the present invention, other polycarboxylic acid components may be copolymerized within the range that does not impair the effects of the present invention. Specifically, examples of aliphatic polycarboxylic acids 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; 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, 1,8-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 the like, which can be used alone or in mixtures of two or more thereof. 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.

[0051] [Polyhydric Alcohol Component] The polyhydric alcohol component of the polyester resin used in the present invention is not particularly limited as long as it can synthesize a polyester resin that exhibits gas barrier filling performance, but it is preferable for the polyhydric alcohol component to contain at least one selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, and 1,3-bishydroxyethylbenzene. Among these, it is most preferable to use ethylene glycol as the main component, because 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.

[0052] In the present invention, it is preferable to use the polyhydric alcohol component described above, but other polyhydric alcohol components may also be copolymerized within the scope of not impairing the effects of the present invention. Specific examples of diols include 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. Examples of trihydric or higher alcohols include glycerol, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl)isocyanurate, 1,2,4-butanetriol, pentaerythritol, and dipentaerythritol. Polyesters containing glycerol and tris(2-hydroxyethyl)isocyanurate in combination are particularly preferred, as they have a moderately high crosslinking density due to their branched structure, resulting in good solubility in organic solvents and excellent barrier function.

[0053] Examples of catalysts used in the reaction to obtain the polyester resin 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 is preferably 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.

[0054] (4) Polyisocyanate-Based Curing Agents In the present invention, when a polyester resin is used as the main component of the coating layer, a polyisocyanate-based curing agent must be used to form a polyurethane 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 is the problem that the liquid cannot be reused after mixing with the curing agent, and a curing (aging) process is required after coating. Examples of advantages include the fact that there is no risk of thickening of the coating liquid in a simple overcoat varnish, 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 terminus of the polyester resin used may be a polyol, a polycarboxylic acid, or a mixture of both. 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.

[0055] When a curing agent is used in the coating layer, a polyisocyanate-based curing agent is preferred from the standpoint of the film's heat resistance, since the coating is applied to 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, a 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 or retort packaging. However, there is also the problem that the liquid cannot be reused after mixing the curing agent, and a curing (aging) process is required after application.

[0056] When the polyester has hydroxyl groups, the polyisocyanate compound used in the present invention reacts at least partially to form a urethane structure, thereby making the resin component highly polar and causing aggregation between polymer chains, thereby further strengthening the gas barrier function. Furthermore, when the resin of the coating material is a linear resin, crosslinking with a trivalent or higher polyisocyanate can impart heat resistance and abrasion resistance. The polyisocyanate compound used in the present invention may be a diisocyanate, a trivalent or higher polyisocyanate, a low-molecular-weight compound, or a high-molecular-weight compound, but it is preferable to contain an aromatic ring or an aliphatic ring as part of the skeleton from the viewpoint of improving the gas barrier function. Examples of isocyanates having an aromatic ring include toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; examples of isocyanates having an aliphatic ring include hydrogenated xylylene diisocyanate, hydrogenated toluene diisocyanate, isophorone diisocyanate, 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. The polyisocyanate compound may be an adduct, allophanate, or biuret. Among these, it is preferable to use a trimethylolpropane adduct of metaxylylene diisocyanate as the polyisocyanate compound.

[0057] (5) High Acid Value Polyester Resin The coating layer preferably contains a polyester resin with an acid value of 5 mgKOH / g or more as the high acid value polyester resin. The high acid value polyester resin used in the present invention preferably has at least one highly polar functional group such as a hydroxy group, an amino group, a carbonyl group, a sulfonic acid group, or a carboxy group. In particular, in the present invention, the high acid value polyester resin preferably contains a trivalent or higher polycarboxylic acid. The trivalent or higher polycarboxylic acid contains, for example, at least one selected from the group consisting of an aromatic polycarboxylic acid and an aliphatic polycarboxylic acid. That is, the trivalent or higher polycarboxylic acid preferably contains at least one of an aromatic polycarboxylic acid residue and an aliphatic polycarboxylic acid residue. The trivalent or higher polycarboxylic acid component may contain only an aromatic polycarboxylic acid component, only an aliphatic polycarboxylic acid component, or both an aromatic polycarboxylic acid component and an aliphatic polycarboxylic acid component.

[0058] The aliphatic polycarboxylic acid may be any of linear, branched, and alicyclic. Examples of the aliphatic polycarboxylic acid include aliphatic tricarboxylic acids such as aconitic acid, cyclohexanetricarboxylic acid, octenetricarboxylic acid, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride, and 1,3,5-cyclohexanetricarboxylic acid; and aliphatic tetracarboxylic acids such as 1,2,3,4-cyclopentanetetracarboxylic acid.

[0059] Examples of aromatic polycarboxylic acids include aromatic tricarboxylic acids such as hemimellitic acid, trimellitic acid and trimellitic anhydride; aromatic tetracarboxylic acids such as pyromellitic acid; and aromatic hexacarboxylic acids such as mellitic acid.

[0060] The acid value of the high acid value polyester resin used in the present invention is preferably 5 mgKOH / g to 100 mgKOH / g, more preferably 10 mgKOH / g to 90 mgKOH / g, even more preferably 20 mgKOH / g to 80 mgKOH / g, and even more preferably 30 mgKOH / g to 70 mgKOH / g. If the acid value is lower than this range, adhesion to metals will decrease, and strong interaction with the inorganic thin film layer will not be achieved, making it impossible to obtain satisfactory gas barrier properties.

[0061] The content of the polyester resin with an acid value of 5 mgKOH / g or more constituting the coating layer is preferably 10 to 65% by mass, more preferably 15 to 65% by mass, and even more preferably 20 to 65% by mass, based on 100% by mass of the solids content of the composition constituting the coating layer. Addition of a high-acid-value polyester resin hydrophilizes the coating layer surface, allowing for uniform and dense deposition of the inorganic thin film layer. This further enhances the gas barrier properties. Addition of an amount exceeding 65% by mass improves the hydrophilicity of the coating layer surface, but reduces the water resistance of the coating layer. This can lead to significant degradation of gas barrier properties after retort treatment when the laminate is formed, or to delamination between the laminate film and the sealable resin layer. On the other hand, addition of an amount less than 10% by mass can prevent the coating layer surface from being able to uniformly and densely deposit the inorganic thin film layer, potentially resulting in unsatisfactory gas barrier properties. From the viewpoint of reducing the oxygen permeability of the laminated body after retort treatment, the content of the polyester resin having an acid value of 5 mgKOH / g or more constituting the coating layer is preferably 10 to 45 mass%, more preferably 15 to 40 mass%, and even more preferably 20 to 40 mass%, based on 100 mass% of the solid content of the composition constituting the coating layer.

[0062] The number average molecular weight of the high acid value polyester resin used in the present invention is not particularly limited as long as it can impart sufficient film toughness, coatability, and solvent solubility as a coating material, but is preferably 1,000 to 10,000, more preferably 2,000 to 7,500, and even more preferably 2,000 to 5,000. If the number average molecular weight is 10,000 or more, the compatibility with other resins in the coating layer will be poor, making it impossible to coat uniformly, which may affect the appearance of the film.

[0063] The coating method for the resin composition for the coating layer is not particularly limited as long as it is a method that can coat the surface of a film to form a layer, and for example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0064] When forming a coating layer, it is preferable to apply the resin composition for the coating layer and then heat-dry it, and the drying temperature is preferably 80 to 145°C, more preferably 85 to 140°C, and even more preferably 90 to 130°C. If the drying temperature is less than 80°C, the coating layer may not be sufficiently dried. On the other hand, if the drying temperature exceeds 145°C, the film may be subjected to too much heat, making it brittle or shrinking, resulting in poor processability. Furthermore, in addition to drying, applying an additional heat treatment at as low a temperature as possible is even more effective in promoting film formation of the coating layer.

[0065] The oxygen permeability of the laminated film is preferably 6500 ml / m 2 · day · MPa or less, more preferably 10 to 6200 ml / m 2 · day · MPa, more preferably 100 to 5900 ml / m 2 day MPa, even more preferably 500 to 5500 ml / m 2 When the coating amount of the coating layer, the ethylene glycol contact angle, and preferably the content of the high acid value polyester resin do not satisfy the above ranges of the present invention, the oxygen permeability of the laminated film is 6500 ml / m 2The oxygen permeability may exceed 1 / 4 day MPa, which may make the product unsuitable for retort applications. The oxygen permeability can be measured, for example, in accordance with JIS-K7126B method using an oxygen permeability measuring device ("OX-TRAN (registered trademark) 1 / 50" manufactured by MOCON Co., Ltd.) in an atmosphere at a temperature of 23°C and a humidity of 65% RH.

[0066] [Inorganic Thin Film Layer] The laminate film of the present invention preferably has an inorganic thin film layer on the surface of the coating layer. The inorganic thin film layer is preferably a thin film made of a metal or an inorganic oxide. There are no particular limitations on the material forming the inorganic thin film layer as long as it can be formed into a thin film. However, from the viewpoint of gas barrier properties, preferred examples include metals such as aluminum, and inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and mixtures of silicon oxide and aluminum oxide. That is, the inorganic thin film layer is preferably made of any one of aluminum, aluminum oxide, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide, more preferably aluminum, silicon oxide, or a composite oxide of silicon oxide and aluminum oxide, and even more preferably silicon oxide. Furthermore, from the viewpoint of achieving both flexibility and density of the thin film layer, a composite oxide of silicon oxide and aluminum oxide is preferred. In this composite oxide, the mixing ratio of silicon oxide to aluminum oxide is preferably 20 to 70% by mass of Al, expressed as the mass ratio of the metals (Al / (Al + Si) × 100). If the Al concentration is less than 20% by mass, the water vapor barrier properties may be reduced. On the other hand, if the Al concentration exceeds 70% by mass, the inorganic thin film layer tends to become hard, and there is a risk that the film will be destroyed during secondary processing such as printing or lamination, resulting in a decrease in gas barrier properties. Furthermore, when the Al concentration is 100% by mass, the water vapor barrier performance is good, but since it is a single material, the surface tends to be smooth, and the slipperiness is poor, making it prone to processing defects (wrinkles, pimples, etc.). Note that silicon oxide here refers to various silicon oxides such as SiO and SiO2, or mixtures thereof, and aluminum oxide refers to various aluminum oxides such as AlO and Al2O3, or mixtures thereof.

[0067] 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 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.

[0068] The method for forming the inorganic thin film layer is not particularly limited, and any known vapor deposition method may be appropriately employed, such as physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD). A typical method for forming the 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, silicon oxide, aluminum oxide, aluminum, a mixture of silicon oxide and aluminum oxide, or a mixture of silicon oxide and aluminum is preferably used as the vapor deposition raw material. These vapor deposition raw materials are typically particles, and the particle size is preferably such that the pressure during vapor deposition does not change, with a preferred particle diameter being 1 mm to 5 mm. Heating methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating can be employed. Furthermore, reactive vapor deposition using reactive gases such as oxygen, nitrogen, hydrogen, argon, carbon dioxide, and water vapor, or ozone addition or ion-assisted deposition can also be employed. Furthermore, the film formation conditions can be changed as desired by applying a bias to the deposition target (the laminated film to be deposited), heating or cooling the deposition target, etc. The deposition material, reactive gas, bias, heating / cooling, etc. of the deposition target can be changed in the same way when the sputtering method or the CVD method is adopted.

[0069] [Protective Layer] In the present invention, a protective layer may be laminated on the inorganic thin film layer when additional gas barrier performance or processing such as printing is required. The metal or inorganic thin film layer is not a completely dense film, but has minute defects scattered therein. 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. In addition, using a material with gas barrier properties for the protective layer itself significantly improves the gas barrier performance of the laminate film. However, it should be noted that providing a protective layer increases costs due to the additional steps and may cause environmental impact depending on the material used. It should also be noted that the protective layer may change physical properties such as surface roughness.

[0070] The amount of the protective layer applied is 0.10 to 0.50 g / m 2 This allows the protective layer to be uniformly controlled during coating, resulting in a film with fewer coating irregularities and defects. In addition, the cohesive force of the protective layer itself is improved, and the adhesion between the inorganic thin film layer and the protective layer is also strengthened. The protective layer deposition amount is 0.50 g / m 2 If the protective layer coating weight exceeds 0.10 g / m, the gas barrier properties are improved, but the cohesive force inside the protective layer becomes insufficient and the uniformity of the protective layer is also reduced, which may result in unevenness or defects in the coat appearance, or in the inability to fully exhibit gas barrier properties and adhesiveness, which is also disadvantageous in terms of cost. 2 If it is less than this, there is a risk that sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0071] Examples of resin compositions used for the protective layer include those obtained by adding a curing agent such as a titanium-based, epoxy-based, isocyanate-based, or melamine-based to a vinyl alcohol-based, urethane-based, polyester-based, acrylic-based, imine-based, or polybutadiene-based resin.

[0072] The method for applying the resin composition for the protective layer is not particularly limited as long as it is a method that can apply the resin composition for the protective layer to the surface of a film to form a layer. For example, a conventional coating method such as gravure coating, reverse roll coating, wire bar coating, or die coating can be used.

[0073] [Laminate Film] The laminate film of the present invention exhibits the following film properties, which are measured and evaluated by the methods described later in the examples.

[0074] The total thickness of the laminated film of the present invention is preferably from 9 μm to 200 μm, more preferably from 10 μm to 150 μm, even more preferably from 12 μm to 100 μm, and particularly preferably from 15 μm to 80 μm.

[0075] The thickness of all the base layers relative to the total thickness of the film is preferably 50% to 99%, more preferably 60% to 97%, particularly preferably 70% to 95%, and most preferably 80% to 92%.

[0076] The contact angle value of ethylene glycol on the coating layer surface of the laminate film of the present invention is 42 to 47°, preferably 42.5 to 46.5°, and more preferably 43 to 46°. The contact angle of ethylene glycol serves as an index of the degree of polarity of the coating layer surface. When this contact angle value is within the above range, the coating layer surface becomes highly polarized, and when an inorganic thin film layer is laminated, the adhesion between the coating layer and the inorganic thin film layer is enhanced, resulting in maximum gas barrier performance. If the contact angle value of ethylene glycol is less than 42°, the amount of polar groups in the coating layer is low, which may result in sparse film formation of the inorganic thin film layer and make it difficult to obtain gas barrier properties. The contact angle of ethylene glycol can be measured as described in the Examples below.

[0077] The water contact angle of the coating layer of the laminate film of the present invention is 60° or more, preferably 60 to 67°, more preferably 61 to 66°, and even more preferably 61 to 65°. The water contact angle serves as an indicator of the water resistance of the coating layer surface. Having this contact angle within the above range improves the water resistance of the coating layer. This makes it possible to provide a laminate film that can exhibit excellent gas barrier properties and good adhesion even after retort treatment of the laminate. If the water contact angle exceeds 67°, the amount of polar groups in the coating layer will be low, resulting in sparse film formation of the inorganic thin film layer, making it difficult to achieve gas barrier properties. If the water contact angle is less than 60°, the coating layer will have poor water resistance, and gas barrier properties and adhesion may be significantly reduced after retort treatment. The water contact angle can be measured as described in the Examples below.

[0078] The oxygen permeability of the laminated film having the inorganic thin film layer laminated thereon under the conditions of 23°C x 65% RH is preferably 1 to 25 ml / m 2 / d / MPa, more preferably 1 to 20 ml / m 2 / d / MPa, more preferably 1 to 19 ml / m 2 / d / MPa, even more preferably 1 to 15 ml / m 2 / d / MPa, particularly preferably 1 to 10 ml / m 2 / d / MPa or less.

[0079] [Laminated Laminate] The present invention encompasses a laminate (laminate laminate) formed by laminating a polyolefin-based sealant layer on one side of a laminate film. When the laminated film of the present invention is used as a packaging material, it is preferable to form a laminate laminate in which a heat-sealing layer called a sealant is formed on the laminate film. The heat-sealing layer is typically provided on the coating layer or inorganic thin film layer side, but may also be provided on the outer side of the base film (the side opposite the inorganic thin film-formed side). The heat-sealing layer is typically formed by extrusion lamination or dry lamination. The thermoplastic polymer forming the heat-sealing layer may be any polymer capable of exhibiting sufficient sealant adhesion, and examples thereof include polyolefin-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 high versatility in terms of durability, seal strength, cost, and monomaterialization, with polypropylene-based resins being most preferred. The thickness of the heat seal layer is preferably 20 to 100 μm, more preferably 30 to 90 μm, and even more preferably 40 to 80 μm. If the thickness is less than 20 μm, sufficient seal strength may not be obtained, and the bag may lack stiffness and be difficult to handle. On the other hand, if the thickness exceeds 100 μm, the bag may be too stiff, making it difficult to handle, and the price may also be high.

[0080] The polypropylene-based resin constituting the heat seal layer preferably contains 80 to 100% by mass of a propylene copolymer, more preferably 85 to 100% by mass, even more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, and particularly preferably 100% by mass.

[0081] The content of the polypropylene-based resin constituting the heat seal layer is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, even more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, and particularly preferably 100% by mass.

[0082] The heat seal layer is preferably a film made of a polypropylene-based resin, more preferably a non-stretched film made of a polypropylene-based resin. In addition to the resin, the heat seal layer may contain additives such as an antiblocking agent and an organic lubricant.

[0083] The thickness of the heat seal layer is, for example, 1 to 100 μm, preferably 5 to 80 μm, more preferably 10 to 70 μm, and even more preferably 20 to 50 μm. The heat seal layer may be a single layer or two or more layers, and may be configured as a laminate layer, a seal layer, an intermediate layer, or the like.

[0084] The oxygen permeability of the laminate of the present invention under the conditions of 23°C x 65% RH is preferably 1 to 20 ml / m 2 / d / MPa, more preferably 1 to 15 ml / m 2 / d / MPa, more preferably 1 to 10 ml / m 2 / d / MPa, even more preferably 1 to 9 ml / m 2 / d / MPa.

[0085] [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 containing poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, or casein as a main component can be used. Among these, urethane adhesives or polyester adhesives are preferred in terms of heat resistance and flexibility that can follow the thermal elongation of each substrate. 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, and the coating weight after drying should be 1 to 8 g / m to achieve sufficient adhesion. 2 is preferable, and more preferably 2 to 7 g / m 2 , more preferably 3 to 6 g / m2 The coating amount is 1 g / m 2 If the thickness is less than 8 g / m, it becomes difficult to bond the entire surface, and the adhesive strength decreases. 2 If the thickness exceeds 100 μm, it takes a long time for the film to completely cure, unreacted material is likely to remain, and adhesive strength decreases. The thickness of the adhesive layer is, for example, 0.1 to 10 μm, preferably 0.5 to 7 μm, and more preferably 1 to 5 μm.

[0086] [Printed Layer] Furthermore, the laminate film of the present invention may have at least one printed layer or other plastic substrate and / or paper substrate laminated between the base film layer and the heat seal layer or on the outer side thereof.

[0087] 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.

[0088] The laminate of the present invention is preferably used as a packaging material, which has excellent gas barrier properties, heat sealability, firmness, and visibility as described above, and can be used as a variety of packaging materials.

[0089] In the present invention, the total thickness of the packaging material (each film and adhesive) is, for example, 140 μm or less, preferably 20 to 140 μm, more preferably 25 to 135 μm, and even more preferably 30 to 130 μm. By setting the total thickness of the packaging material within this range, a package can be obtained that exhibits the necessary physical properties, such as firmness, toughness, and barrier performance, required for the packaging material. If the total thickness is less than 20 μm, the bag will not have enough firmness and will not stand on its own. On the other hand, if the total thickness exceeds 140 μm, a high heat-sealing temperature is required to exhibit sufficient heat-sealing strength, which may result in poor appearance such as wrinkles and distortion. Furthermore, this increases the cost of the package, which is economically undesirable.

[0090] The form of the package using the packaging material of the present invention is not particularly limited and can take various forms, such as a three-sided or four-sided pouch, a standing pouch, a spout pouch, etc.

[0091] The present invention also encompasses a package in which an item to be packaged is packaged in a packaging material. The content to be filled in a packaging bag using the packaging material of the present invention is not particularly limited, and the content may be a liquid, powder, or gel.

[0092] [Laminate after retort treatment] The produced laminate is subjected to retort treatment by being kept in pressurized hot water at 120°C for 30 minutes to obtain a laminate after retort treatment. The oxygen transmission rate of the laminate after retort treatment of the present invention under the conditions of 23°C x 65% RH is preferably 1 to 50 ml / m 2 / d / MPa, more preferably 1 to 35 ml / m 2 / d / MPa, more preferably 1 to 20 ml / m 2 / d / MPa, even more preferably 1 to 15 ml / m 2 / d / MPa, particularly preferably 1 to 10 ml / m 2 / d / MPa.

[0093] The laminate strength of the laminate after retort treatment, in which the laminate is subjected to retort treatment, is preferably 1 N / 15 mm or more, more preferably 1 to 15 N / 15 mm, even more preferably 1.5 to 12 N / 15 mm, still more preferably 2 to 10 N / 15 mm, and particularly preferably 2.5 to 10 N / 15 mm. Furthermore, the laminate strength of a laminate in which water is applied between the base film and the heat seal layer is preferably 1 to 15 N / 15 mm, more preferably 1.1 to 12 N / 15 mm, and even more preferably 1.2 to 10 N / 15 mm. The above-mentioned laminate strength can be determined by the method described in the Examples below.

[0094] This application claims the benefit of priority based on Japanese Patent Application No. 2023-174542, filed on October 6, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-174542, filed on October 6, 2023, are incorporated herein by reference.

[0095] 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 evaluation methods and physical property measurement methods used in each example and comparative example are as follows.

[0096] (1) Thickness of Various Films The thickness was measured using a dial gauge in accordance with JIS K7130-1999 Method A.

[0097] (2) Mesopentad fraction ([mmmm] unit: %) The mesopentad fraction was measured by 13 The mesopentad fraction was calculated according to the method described in "Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973)". 13 C-NMR measurement was performed using an AVANCE 500 manufactured by BRUKER at 110°C by dissolving 200 mg of a sample in a mixed solution of o-dichlorobenzene and deuterated benzene at a volume ratio of 8:2 at 135°C.

[0098] (3) Melt flow rate ([MFR] g / 10 min) Measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kgf. In the case of raw resin, the required amount of pellets (powder) was weighed out and used. In the case of film, the required amount was cut out and then cut into approximately 5 mm square samples.

[0099] (4) Molecular Weight and Molecular Weight Distribution The molecular weight and molecular weight distribution of the raw resin and film were determined using gel permeation chromatography (GPC) with monodisperse polystyrene as the standard. The measurement conditions for the column, solvent, etc. used in the GPC measurement are as follows: Solvent: 1,2,4-trichlorobenzene Column: TSKgel GMHHR-H(20)HT x 3 Flow rate: 1.0 ml / min Detector: RI Measurement temperature: 140°C

[0100] The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) are defined by the following equations, where Mn is the molecular weight (Mi) at each elution position of the GPC curve obtained via the molecular weight calibration curve, and Ni is the number of molecules. Number average molecular weight: Mn = Σ(Ni·Mi) / ΣNi Weight average molecular weight: Mw = Σ(Ni·Mi) ２ ) / Σ(Ni·Mi) Molecular weight distribution: Mw / Mn When the baseline was unclear, the baseline was set in the range up to the lowest point of the high molecular weight base of the elution peak on the high molecular weight side closest to the elution peak of the standard substance.

[0101] (5) Melting Peak Temperature (°C) and Melting Peak Area (J / g) Measurements were performed using a differential scanning calorimeter (DSC) manufactured by SII, with a sample weight of 10 mg and a heating rate of 20°C / min. The melting endothermic peak temperature and the melting peak area were determined from the DSC curve.

[0102] (6) Method for Evaluating Contact Angle Values ​​of Ethylene Glycol and Water First, each laminate film obtained in the Examples and Comparative Examples was left for 4 days in an atmosphere of room temperature 40°C and relative humidity 15%. Then, in an atmosphere of room temperature 23°C and relative humidity 65%, a water contact angle measuring device ("KRUSS DSA100" manufactured by SANYO TRADING CO., LTD.) was used to measure the coating layer of the laminate film using the sessile drop method. 2 μl of ethylene glycol or water was dropped on the surface of the coating layer, and the contact angle value was measured 1 second after the drop.

[0103] (7) Amount of Coating Layer Adhesion In each of the Examples and Comparative Examples, each laminated film obtained at the stage of laminating the coating layer on the substrate film was used as a sample, and a test piece of 100 mm x 100 mm was cut out from this sample, and the coating layer was wiped off with acetone. The amount of adhesion was calculated from the change in mass of the film before and after wiping.

[0104] (8) Evaluation Method of Oxygen Permeability The oxygen permeability of the laminated films obtained in each Example and Comparative Example was measured in accordance with JIS-K7126B method using an oxygen permeability measuring device ("OX-TRAN (registered trademark) 1 / 50" manufactured by MOCON Co., Ltd.) under an atmosphere of a temperature of 23°C and a humidity of 65% RH. The oxygen permeability was measured in the direction in which oxygen permeated from the substrate layer side.

[0105] (9) Evaluation method of laminate strength The retort-treated laminate prepared by the method described below 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 material 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 defined as the strength when the polyolefin substrate film and the unstretched polypropylene film were peeled at a peel angle of 90 degrees at a tensile speed of 200 mm / min. The same method was used to peel the polyolefin substrate film and the unstretched polypropylene film when water was applied between them.

[0106] [Preparation of Base Film Layer] Tables 1 to 3 show the polypropylene resins, film forming conditions, and raw material blend ratios used in preparing the polyolefin base film described below.

[0107]

[0108]

[0109]

[0110] (OPP-1) For the base layer (A), polypropylene homopolymer PP-1 shown in Table 1 was used. For the surface layer (B), a blend of 43.2 mass% of polypropylene homopolymer PP-2 shown in Table 1, 52.0 mass% of ethylene copolymerized polypropylene polymer PP-3 shown in Table 1, and 4.8 mass% of antiblocking agent-containing masterbatch FTX0627G was used. In this case, the melt flow rate of the polypropylene resin composition constituting the surface layer (B) was 3 g / 10 min.

[0111] For the surface layer (C), a mixture of 93.6% by mass of polypropylene homopolymer PP-1 shown in Table 1 and 6.4% by mass of antiblocking agent-containing masterbatch FTX0627G was used.

[0112] The base layer (A) was made 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 material resins were melted at 250 ° C. and co-extruded from a T-die into a sheet. The surface layer (B) was cooled and solidified so that it contacted 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 width direction (TD) were clamped with clips, preheated at 173 ° C., stretched 8.2 times in the width direction (TD) at 164 ° C., and heat-set at 171 ° C. while relaxing 6.7% in the width direction (TD). The film-forming conditions at this time were designated film-forming conditions a. In this way, a biaxially oriented polypropylene film having a configuration of surface layer (B) / base layer (A) / surface layer (C) was obtained.

[0113] The surface of the surface layer (B) of the biaxially stretched polypropylene film was subjected to a corona treatment using a corona treater manufactured by Softal Corona & Plasma GmbH under the condition of an applied current value of 0.75 A, and then the film was wound up with a winder. The thickness of the obtained substrate film was 20 μm (thicknesses of surface layer (B) / substrate layer (A) / surface layer (C) were 1.3 μm / 17.7 μm / 1.0 μm).

[0114] [Preparation of Coating Layer] The method for preparing the coating layer used in each of the Examples and Comparative Examples is described below. [Polyester Resin (A)] As the polyester component, polyester polyol (DF-COAT GEC-004C manufactured by DIC Corporation: solid content 30%) was used.

[0115] [Polyisocyanate Crosslinking Agent (B)] As the polyisocyanate crosslinking agent, a trimethylolpropane adduct of metaxylylene diisocyanate ("Takenate D-110N" manufactured by Mitsui Chemicals, Inc.: solid content 75%) was used.

[0116] [Silane Coupling Agent (C)] 3-aminopropyltriethoxysilane ("KBE-903" manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silane coupling agent.

[0117] [High Acid Value Polyester Resin (D)] As the high acid value polyester resin (D-1), a water-soluble polyester resin ("Pluscoat Z-730" manufactured by GOO Chemical Industry Co., Ltd.; solid content 100%, acid value 40 to 60 mg KOH / g, molecular weight: 3000) was used. As the high acid value polyester resin (D-2), a water-soluble polyester resin ("Pluscoat Z-760" manufactured by GOO Chemical Industry Co., Ltd.; solid content 100%, acid value 40 to 60 mg KOH / g, molecular weight: 3000) was used.

[0118] [Polyester Resin (E) Not Containing Highly Polar Groups] A low molecular weight polyester resin ("Vylon RV220" manufactured by Toyobo MC Co., Ltd.; solid content 100%, acid value 1.5 mgKOH / g, molecular weight: 3000) was used as the polyester resin not containing highly polar groups.

[0119] Preparation of Coating Liquids 1 to 19 for Forming a Coating Layer [Coating Liquid 1] A solution (15% by mass) of silane coupling agent (C) dissolved in acetone and polyisocyanate crosslinking agent (B) were mixed in the following ratio and stirred for 10 minutes using a magnetic stirrer. The resulting mixture was diluted with methyl ethyl ketone and 1-methoxy-2-propanol (hereinafter referred to as PGM), and polyester resin (A) was added. Finally, a solution (20% by mass) of high acid value polyester resin (D-1) dissolved in methyl ethyl ketone was added to obtain the target Coating Liquid 1. The mixing ratios are as follows: Polyester resin (A) 5.83% by mass Polyisocyanate crosslinking agent (B) 5.59% by mass Silane coupling agent (C) 0.48% by mass High acid value polyester resin (D-1) 5.10% by mass Methyl ethyl ketone 67.85% by mass PGM 12.45% by mass Acetone 2.70% by mass

[0120] [Coating Liquid 2] The following components were mixed to prepare Coating Liquid 2: Polyester resin (A) 7.08% by mass, Polyisocyanate crosslinking agent (B) 6.79% by mass, Silane coupling agent (C) 0.58% by mass, High acid value polyester resin (D-1) 2.55% by mass, Methyl ethyl ketone 67.27% by mass, PGM 12.45% by mass, Acetone 3.28% by mass

[0121] [Coating Liquid 3] The following components were mixed to prepare Coating Liquid 3. Polyester resin (A) 6.66% by mass Polyisocyanate crosslinking agent (B) 6.39% by mass Silane coupling agent (C) 0.54% by mass High acid value polyester resin (D-1) 3.40% by mass Methyl ethyl ketone 67.47% by mass PGM 12.45% by mass Acetone 3.08% by mass

[0122] [Coating Liquid 4] The following components were mixed to prepare Coating Liquid 4: Polyester resin (A) 6.25% by mass, Polyisocyanate crosslinking agent (B) 5.99% by mass, Silane coupling agent (C) 0.51% by mass, High acid value polyester resin (D-1) 4.25% by mass, Methyl ethyl ketone 67.66% by mass, PGM 12.45% by mass, Acetone 2.89% by mass

[0123] [Coating Liquid 5] The following components were mixed to prepare Coating Liquid 5. Polyester resin (A) 4.58% by mass Polyisocyanate crosslinking agent (B) 4.39% by mass Silane coupling agent (C) 0.37% by mass High acid value polyester resin (D-1) 7.65% by mass Methyl ethyl ketone 68.43% by mass PGM 12.45% by mass Acetone 2.12% by mass

[0124] [Coating Liquid 6] The following components were mixed to prepare Coating Liquid 6. Polyester resin (A) 6.66% by mass Polyisocyanate crosslinking agent (B) 6.39% by mass Silane coupling agent (C) 0.54% by mass High acid value polyester resin (D-2) 3.40% by mass Methyl ethyl ketone 67.47% by mass PGM 12.45% by mass Acetone 3.08% by mass

[0125] [Coating Liquid 7] The following components were mixed to prepare Coating Liquid 7. Polyester resin (A) 5.83% by mass Polyisocyanate crosslinking agent (B) 5.59% by mass Silane coupling agent (C) 0.48% by mass High acid value polyester resin (D-2) 5.10% by mass Methyl ethyl ketone 67.85% by mass PGM 12.45% by mass Acetone 2.70% by mass

[0126] [Coating Liquid 8] The following components were mixed to prepare Coating Liquid 8. Polyester resin (A) 5.00% by mass Polyisocyanate crosslinking agent (B) 4.79% by mass Silane coupling agent (C) 0.41% by mass High acid value polyester resin (D-2) 6.80% by mass Methyl ethyl ketone 68.24% by mass PGM 12.45% by mass Acetone 2.31% by mass

[0127] [Coating Liquid 9] The following components were mixed to prepare Coating Liquid 9. Polyester resin (A) 4.17% by mass Polyisocyanate crosslinking agent (B) 4.00% by mass Silane coupling agent (C) 0.34% by mass High acid value polyester resin (D-2) 8.50% by mass Methyl ethyl ketone 68.62% by mass PGM 12.45% by mass Acetone 1.93% by mass

[0128] [Coating Liquid 10] The following components were mixed to prepare Coating Liquid 10: Polyester resin (A) 8.33% by mass, Polyisocyanate crosslinking agent (B) 7.99% by mass, Silane coupling agent (C) 0.68% by mass, Methyl ethyl ketone 66.70% by mass, PGM 12.45% by mass, Acetone 3.85% by mass

[0129] [Coating Liquid 11] The following components were mixed to prepare Coating Liquid 11: Polyester resin (A) 2.21% by mass, Polyisocyanate crosslinking agent (B) 2.12% by mass, Silane coupling agent (C) 0.18% by mass, Methyl ethyl ketone 80.16% by mass, PGM 14.33% by mass, Acetone 1.02% by mass

[0130] [Coating Liquid 12] The following components were mixed to prepare Coating Liquid 12: Polyester resin (A) 3.33% by mass, Polyisocyanate crosslinking agent (B) 3.20% by mass, Silane coupling agent (C) 0.27% by mass, High acid value polyester resin (D-1) 10.20% by mass, Methyl ethyl ketone 69.01% by mass, PGM 12.45% by mass, Acetone 1.54% by mass

[0131] [Coating Liquid 13] The following components were mixed to prepare Coating Liquid 13. Polyester resin (A) 1.67% by mass Polyisocyanate crosslinking agent (B) 1.60% by mass Silane coupling agent (C) 0.14% by mass High acid value polyester resin (D-1) 13.60% by mass Methyl ethyl ketone 69.78% by mass PGM 12.45% by mass Acetone 0.77% by mass

[0132] [Coating Liquid 14] The following components were mixed to prepare Coating Liquid 14: High acid value polyester resin (D-1) 17.00% by mass Methyl ethyl ketone 70.55% by mass PGM 12.45% by mass

[0133] [Coating Liquid 15] The following components were mixed to prepare Coating Liquid 15: High acid value polyester resin (D-2) 17.00% by mass Methyl ethyl ketone 70.55% by mass PGM 12.45% by mass

[0134] [Coating Liquid 16] The following components were mixed to prepare Coating Liquid 16: Highly polar group-free polyester resin (E) 5.83% by mass, Polyisocyanate crosslinking agent (B) 5.59% by mass, Silane coupling agent (C) 0.48% by mass, Methyl ethyl ketone 67.85% by mass, PGM 12.45% by mass, Acetone 2.70% by mass

[0135] [Coating Liquid 17] The following components were mixed to prepare Coating Liquid 17: Highly polar group-free polyester resin (E) 17.00% by mass, Methyl ethyl ketone 70.55% by mass, PGM 12.45% by mass

[0136] [Coating Solution 18] To a mixed solution of 42.83 parts by mass of purified water and 20.00 parts by mass of isopropanol, 6.67 parts by mass of a commercially available metaxylylene group-containing urethane resin dispersion ("Takelac (registered trademark) WPB341" manufactured by Mitsui Chemicals, Inc.; solids content 30%) and 28.00 parts by mass of a commercially available polyester urethane resin dispersion ("Hydran (registered trademark) AP-80" manufactured by DIC Corporation; solids content 25%) were added, and the mixture was stirred for 10 minutes using a magnetic stirrer. 2.50 parts by mass of a carbodiimide crosslinking agent ("Carbodilite SV-02" manufactured by Nisshinbo Chemical Inc.; solids content 40%) was further added to the obtained mixed solution to obtain the target Coating Solution 18.

[0137] [Coating Liquid 19] To 90% by mass of purified water was added 10% by mass of a fully saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: G Polymer OKS8049Q (saponification degree 99.0% or more, average polymerization degree 450)), and the mixture was heated to 80°C with stirring, and then stirred for about 1 hour. Thereafter, the mixture was cooled to room temperature, thereby obtaining Coating Liquid 19 with a solids content of 10%.

[0138] [Preparation of Laminated Film] (Example 1) OPP-1 was used for the base film, and Coating Solution 1 was used for the coating layer. The corona-treated surface of the base film was coated by gravure roll coating, and then dried for 10 seconds in a dry oven at 120°C. The coating layer adhesion amount at this time was 1.50 g / m 2 Thereafter, a post-heat treatment was carried out at 40° C. for 2 days to obtain the desired laminated film.

[0139] Example 2 The target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 2 was used as the coating layer.

[0140] Example 3 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 3 was used as the coating layer.

[0141] Example 4 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 4 was used as the coating layer.

[0142] Example 5 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 5 was used as the coating layer.

[0143] Example 6 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 6 was used as the coating layer.

[0144] Example 7 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 7 was used as the coating layer.

[0145] Example 8 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 8 was used as the coating layer.

[0146] Example 9 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 9 was used as the coating layer.

[0147] (Example 10) Coating amount of coating layer: 1.40 g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature.

[0148] (Example 11) Coating amount of coating layer: 1.80 g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature.

[0149] (Example 12) Coating amount of coating layer: 2.10 g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature.

[0150] Example 13 The target laminated film was obtained under the same conditions as in Example 1, except that the drying temperature was changed to 80°C.

[0151] Example 14 The target laminated film was obtained under the same conditions as in Example 1, except that the drying temperature was changed to 100°C.

[0152] Example 15 The target laminated film was obtained under the same conditions as in Example 1, except that the drying temperature was changed to 130°C.

[0153] Example 16 The target laminated film was obtained under the same conditions as in Example 1, except that the drying temperature was changed to 140°C.

[0154] Comparative Example 1 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 10 was used as the coating layer.

[0155] Comparative Example 2 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 11 was used as the coating layer.

[0156] Comparative Example 3 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 12 was used as the coating layer.

[0157] Comparative Example 4 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 13 was used as the coating layer.

[0158] Comparative Example 5 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 14 was used as the coating layer.

[0159] (Comparative Example 6) Coating amount of coating layer: 0.70 g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature.

[0160] (Comparative Example 7) Coating amount of coating layer: 1.00 g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature.

[0161] (Comparative Example 8) Coating amount of coating layer: 1.30 g / m 2 The target laminated film was obtained under the same conditions as in Example 1, except for changing the temperature.

[0162] Comparative Example 9 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 15 was used as the coating layer.

[0163] Comparative Example 10 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 16 was used as the coating layer.

[0164] Comparative Example 11 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 17 was used as the coating layer.

[0165] Comparative Example 12 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 18 was used as the coating layer.

[0166] Comparative Example 13 A target laminated film was obtained under the same conditions as in Example 1, except that Coating Liquid 19 was used as the coating layer.

[0167] [Formation of Inorganic Thin Film Layer] The method for producing the inorganic thin film layer used in each example and comparative example is described below. Silicon oxide was vapor-deposited on the coating layer to form the inorganic thin film layer. A small vacuum vapor deposition apparatus (VWR-400 / ERH, manufactured by ULVAC KIKO Co., Ltd.) was used to vapor-deposit silicon oxide onto the coating layer. -3 After reducing the pressure to below 1 Pa, granular silicon monoxide was placed in a Nilaco evaporation source B-110 from below the substrate, and evaporated by heating to form a silicon oxide film (M-1) with a thickness of 30 nm on the coating layer formed on the base film.

[0168] (1) Preparation of Laminated Body A polyurethane adhesive (TM569 / cat10L manufactured by Toyo-Morton Co., Ltd.) was applied onto the inorganic thin film layer-containing laminated film obtained in the Examples and Comparative Examples so that the thickness after drying treatment at 80°C would be 3 μm, and then an unstretched polypropylene film (P1153 manufactured by Toyobo Co., Ltd.; thickness 50 μm; referred to as CPP) was dry-laminated and aged at 40°C for 4 days to obtain a laminated body for evaluation.

[0169] Next, the laminate produced in (1) above was subjected to a retort treatment by being held in pressurized hot water at 120° C. for 30 minutes, to obtain a retort-treated laminate.

[0170] As described above, laminate films, laminated bodies, and laminated bodies after retort treatment were produced. The raw materials and production methods of the films used in the above examples and comparative examples are shown in Tables 1 to 3. In addition, the results of various evaluations of the obtained laminated films and the like are shown in Table 4.

[0171]

[0172]

[0173]

[0174] According to the present invention, it is possible to provide a laminate film that can form a laminate structure composed of almost a single resin type, mainly a polypropylene film, which has a low environmental impact, and that, when an inorganic thin film layer is laminated thereon, exhibits excellent gas barrier properties and good adhesion even after retort treatment. According to a more preferred embodiment of the present invention, it is possible to provide a laminate film that exhibits excellent gas barrier properties even after the formation of an inorganic thin film layer. According to a further preferred embodiment of the present invention, it is possible to provide a laminate film that exhibits excellent gas barrier properties both before and after the formation of an inorganic thin film layer.

Claims

1. A laminate film for forming an inorganic thin film layer, comprising a base layer mainly composed of a polypropylene resin and a coating layer laminated on at least one surface of the base layer, the laminate film satisfying the following requirements (I) to (III): (I) The contact angle value of ethylene glycol on the surface of the coating layer of the laminate film is 42 to 47°. (II) The contact angle value of water on the surface of the coating layer of the laminate film is 60° or more. (III) The coating layer has a coating weight of 1.40 g / m 2 That's all.

2. The oxygen permeability of the laminated film is 6,500 ml / m 2 2. The laminated film according to claim 1, wherein the compressive strength is 0.05 MPa or less.

3. The laminate film according to claim 1 or 2, wherein the coating layer contains a polyester resin having an acid value of 5 mg KOH / g or more.

4. The laminated film according to claim 1 or 2, wherein the coating layer further contains a polyurethane resin.

5. A laminate film as described in claim 3, wherein the content of the polyester resin constituting the coating layer and having an acid value of 5 mg KOH / g or more is 10 to 65 mass % based on 100 mass % of the solids content of the composition constituting the coating layer.

6. The laminate film according to claim 1 or 2, wherein an inorganic thin film layer is laminated on the coating layer of the laminate film.

7. The laminate film according to claim 6, wherein the inorganic thin film layer is composed of at least one material selected from the group consisting of aluminum, silicon oxide, aluminum oxide, and a mixture of silicon oxide and aluminum oxide.

8. The oxygen permeability of the laminated film having an inorganic thin layer laminated thereon is 1 to 25 ml / m under conditions of 23°C x 65% RH. 2 The laminated film according to claim 6, wherein the modulus is 1 / d / MPa.

9. A laminate comprising the laminate film according to claim 1 or 2 and a polyolefin sealant layer laminated on one side of the laminate film.

10. The laminate is subjected to retort treatment, and the oxygen permeability of the laminate after retort treatment is 50 ml / m 2 The laminate according to claim 9, wherein the modulus is less than or equal to 1 day MPa.

11. The laminate according to claim 9, wherein the laminate after retort treatment has a laminate strength of 1.0 N / 15 mm or more.