Laminated film

Abstract

To provide a laminate film which is a film capable of forming a lamination constitution composed of a substantially single resin type that mainly contains a polypropylene film and has less environmental loads, and has gas barrier property and adhesion required for a packaging material.SOLUTION: A laminate film has a surface layer (B) composed of a polypropylene-based resin composition on one surface of a base material layer (A) containing a polypropylene-based resin as a main component, and a surface layer (C) composed of a polypropylene-based resin composition on the other surface of the base material layer (A), and has an inorganic thin film layer (D) stacked on the surface layer (B), wherein the laminate film has tensile elastic modulus in an MD direction of 2.6 GPa or less and tensile elastic modulus in a TD direction of 4.1 GPa or more, and a haze of 5% or less, and the surface on the inorganic thin film layer (D) side of the laminate film satisfies requirements (I) to (IV). (I) Arithmetic average roughness (Ra) measured in the rage of 2 μm square by a scanning probe microscope is 4.5 nm or more and 9.0 nm or less. (II) Martens hardness is 310 N / mm2 or less. (III) Water contact angle is 10° or more and 75° or less. (IV) Central surface average roughness (SRa) measured by three-dimensional roughness meter is 0.010 μm or more and 0.040 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a laminated film. More specifically, it relates to a gas barrier laminated film that has low environmental impact during manufacturing and disposal, and possesses both excellent gas barrier performance and sufficient adhesive strength between layers for use as a packaging material.

[0002] In recent years, regulations aimed at reducing the use of single-use plastics have been strengthened in Europe and around the world. This is due to a growing international awareness of resource recycling and the worsening waste problem in emerging countries. As a result, there is a demand for environmentally friendly products from the perspective of the 3Rs (recycle, reuse, reduce) for plastic packaging materials used for food, pharmaceuticals, and other products.

[0003] The performance requirements for the aforementioned environmentally friendly packaging materials include: (1) being made of easily recyclable materials, (2) having gas barrier properties that can block various gases and extend the shelf life, and (3) having a laminate structure that has a low environmental impact (for example, not using organic solvents, using a small amount of material, and being recyclable through monomaterialization).

[0004] In recent years, attention has been focused on the use of polypropylene film in order to enable the above (2) and (3). Polypropylene film is widely used in a variety of applications, such as packaging for food and various products, electrical insulation, and surface protection films. Due to its molecular structure, polypropylene film can exhibit high water vapor barrier properties. Furthermore, since polypropylene-based and polyethylene-based heat-seal resins are commonly used as sealants to bond with surface substrate films, for example, by using polypropylene film as the surface substrate and an unstretched polypropylene sheet as the sealant, it is possible to achieve monomaterial packaging as a whole while maintaining gas barrier properties, enabling environmentally friendly packaging designs that are easy to recycle.

[0005] However, regarding the gas barrier properties mentioned in (2) above, although polypropylene films have water vapor barrier properties, they are not sufficient compared to, for example, transparent inorganic vapor-deposited polyester films which are generally considered to have excellent water vapor barrier properties, and they also have the problem of having very poor oxygen barrier properties. In response to this, films have been used in which polypropylene films are laminated with polymer resin compositions that are generally said to have relatively high oxygen barrier properties, such as polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyvinylidene chloride resin, and polyacrylonitrile (see, for example, Patent Documents 1 to 3).

[0006] However, gas barrier coating films made using the above-mentioned polymer resin compositions of polyvinyl alcohol or ethylene vinyl alcohol copolymers exhibit high humidity dependence, resulting in reduced gas barrier properties under high humidity conditions, and insufficient water vapor barrier properties and water-resistant adhesion. Furthermore, while polyvinylidene chloride resin and polyacrylonitrile have low humidity dependence, they suffer from insufficient water vapor barrier properties and a high risk of generating harmful substances during disposal and incineration.

[0007] Furthermore, all of the aforementioned barrier coating layers required a film thickness of 1 μm or more to achieve sufficient barrier performance. However, thick barrier coating layers could potentially introduce impurities during recycling, making recycling itself difficult. It was also unsuitable from the perspective of monomaterialization using a single material. Additionally, there were issues with printing defects due to uneven coating and surface irregularities during processing steps such as printing.

[0008] To address these issues, gas barrier laminates are commonly used, which consist of a thin metal film made of aluminum or the like, or an inorganic thin film made of inorganic oxides such as silicon dioxide or aluminum oxide, formed on the surface of a plastic substrate film such as polyester film. Among these, those with thin films of inorganic oxides such as silicon dioxide, aluminum oxide, or mixtures thereof are widely used because they do not require aluminum foil, are transparent allowing for confirmation of the contents, and the formed film is very thin and does not hinder recyclability.

[0009] Methods have been disclosed for imparting gas barrier properties to polypropylene films by laminating inorganic thin films (for example, Patent Document 4). However, it has been pointed out that polypropylene films have low surface energy due to the nonpolar nature of their molecules, and therefore the adhesion is insufficient when processing inorganic thin films.

[0010] Furthermore, in the formation of inorganic thin film layers, not only is adhesion a problem, but protrusions due to surface irregularities can prevent thin film formation, resulting in poor barrier properties. On the other hand, biaxially oriented polypropylene films have poor slipperiness due to their excellent flexibility and flatness, and blocking occurs where the films stick together. Therefore, antiblocking agents are generally added to create surface irregularities. As a result, thin film formation by vapor deposition or coating becomes insufficient due to the formed surface irregularities, leading to problems such as poor barrier properties.

[0011] To address these problems, various methods have been proposed to improve polypropylene films. For example, a method has been disclosed in which branched polypropylene is mixed with propylene resin, and the β-crystal of the polypropylene is transformed into an α-crystal to form irregularities on the film surface, thereby improving slipperiness without substantially using inorganic or organic antiblocking agents (see, for example, Patent Document 5). However, because only homopolypropylene with high stereoregularity is used, the surface is hard, and adhesion when used for processing such as vapor deposition, coating, and lamination is not considered.

[0012] On the one hand, a method is disclosed in which an antistatic agent is eliminated as much as possible, and surface irregularities of the resin itself are formed due to the difference in melt flow rate (MFR) between a copolymer of polypropylene resin, propylene, ethylene, and / or an α-olefin having 4 or more carbon atoms in the film surface layer, thereby increasing the adhesion in lamination with ink or other member films (see, for example, Patent Document 6, etc.). However, the arithmetic mean roughness (SRa) of the surface layer is high, which is insufficient for forming a thin film by vapor deposition or coating, and the barrier property and the like may deteriorate. In addition, there is no antiblocking agent on one surface of the film, and wrinkles or blocking may occur in the roll state.

[0013] Also, as another method other than improving the substrate, it is possible to improve the adhesion by separately providing an organic solvent-based coating layer that contributes to the adhesion and barrier properties on the surface of the substrate, but the adhesive force is not sufficient. In addition, the number of processing steps by coating increases, and since an organic solvent is used, it is not desirable from the viewpoint of reducing the environmental load, and it has been desired to obtain an adhesive force without an adhesive layer by coating.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0015] The barrier properties and adhesion in the above-mentioned Patent Documents 1-4 were insufficient. Patent Documents 5 and 6 did not examine improvements in barrier properties and adhesion to inorganic thin film layers. Furthermore, none of the documents designed materials that satisfied the performance requirements for the aforementioned environmentally friendly packaging materials.

[0016] This invention was made against the backdrop of the problems of the prior art described above. In other words, the objective of the present invention is to provide a laminated film that can form a laminate structure composed of almost a single resin type with low environmental impact, mainly polypropylene film, and that has the necessary performance characteristics such as gas barrier properties, adhesiveness, and processability required for packaging materials. [Means for solving the problem]

[0017] The inventors of this invention have discovered that by designing a predetermined polypropylene film substrate layer to match the required performance and laminating an inorganic thin film layer on top of it, it is possible to significantly improve gas barrier performance and adhesion, and furthermore, to provide a film with a low environmental impact, thereby completing the present invention.

[0018] In other words, the present invention consists of the following configuration. 1. A laminated film having a base layer (A) mainly composed of a polypropylene resin, a surface layer (B) on one surface of the base layer (A), a surface layer (C) on the other surface of the base layer (A), and further having an inorganic thin film layer (D) laminated on the surface layer (B), characterized in that the haze of the laminated film is 5% or less and the inorganic thin film layer (D) side surface of the laminated film satisfies the following requirements (I) to (IV). (I) Arithmetic mean roughness (Ra) measured by scanning probe microscopy is 4.5 nm or greater and 9.0 nm or less. (II) Martens hardness of 310 N / mm 2 below (III) Water contact angle is 75° or less (IV) Center surface mean roughness (SRa) measured by a 3D roughness meter is 0.010 μm or greater and 0.040 μm or less. 2. The oxygen permeability of the laminated film under a 23°C × 65%RH environment is 60 cc / m². 2 • d·atm or less, and water vapor transmission rate of 4 g / m³ under 40°C × 90% RH conditions. 2 The laminated film described in 1, characterized in that it is less than or equal to d. 3. The laminated film according to 1. or 2., characterized in that when the oxygen permeability value of the laminated film measured under 23°C × 65%RH conditions is (A) and the oxygen permeability value measured under 23°C × 80%RH conditions is (B), the rate of deterioration of the barrier value under high temperature and high humidity conditions, expressed by the following formula, is 130% or less. Barrier value deterioration rate (%) under high temperature and high humidity conditions = (B / A) × 100 Equation (1) 4. The laminated film according to any one of 1 to 3, characterized in that the mean center surface roughness (SRa) measured by a three-dimensional roughness meter on the surface of the surface layer (C) of the laminated film is 0.020 μm or more. 5. The Martens hardness of the surface on the surface layer (C) side of the laminated film is 270 N / mm². 2 A laminated film according to any one of 1. to 4., characterized by the above. 6. A laminated film according to any one of claims 1 to 5, wherein the laminated film thickness is 9 μm to 200 μm. 7. A packaging material comprising a laminated olefin-based sealant layer laminated on one side of a laminated film as described in any of 1. to 6. above. [Effects of the Invention]

[0019] Through this technology, the inventors have made it possible to provide a laminated film that possesses the necessary properties, such as barrier properties and adhesive properties, required for packaging materials, while also being environmentally conscious. [Brief explanation of the drawing]

[0020] [Figure 1] This figure shows the method for measuring air leakage time according to the present invention. [Modes for carrying out the invention]

[0021] The present invention will be described in detail below. The laminated film of the present invention is a laminated film having a surface layer (B) on one surface of a base layer (A) mainly composed of a polypropylene resin, a surface layer (C) on the other surface of the base layer (A), and further having an inorganic thin film layer (D) laminated on the surface layer (B), characterized in that the haze of the laminated film is 5% or less and the inorganic thin film layer (D) side surface of the laminated film satisfies the following requirements (I) to (IV). (I) The arithmetic mean roughness (Ra) measured by scanning probe microscopy is 4.5 nm or greater and ~9.0 nm or less. (II) Martens hardness of 310 N / mm 2 The following applies: (III) The water contact angle is 75° or less. (IV) The mean center surface roughness (SRa) measured by a 3D roughness meter is 0.010 μm or greater and 0.040 μm or less. The following describes each layer of the laminated film.

[0022] [Base film layer] (1) Base material layer (A) The base layer (A) constituting the laminated film of the present invention, which mainly consists of a polypropylene resin, is preferably a biaxially oriented film. The polypropylene used in this layer may also be polypropylene copolymerized with ethylene and / or α-olefins having 4 or more carbon atoms in an amount of 0.5 mol% or less. Such copolymerized polypropylene is also included in the polypropylene of the present invention (hereinafter referred to as polypropylene). The copolymerized component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and completely homopolypropylene without copolymerized components is most preferred. When ethylene and / or α-olefins with 4 or more carbon atoms are copolymerized in amounts exceeding 0.5 mol%, their crystallinity and rigidity may decrease excessively, leading to a high thermal shrinkage rate at high temperatures. Such resins may be used in blends.

[0023] The mesopentade fraction ([mmmm]%), measured by 13C-NMR, which is an indicator of the stereoregularity of the polypropylene constituting the base layer (A) of the polypropylene laminated film of the present invention, is preferably 98 to 99.5%. More preferably, it is 98.1% or higher, and even more preferably 98.2% or higher. If the mesopentade fraction of the polypropylene is low, the elastic modulus will be low, and the heat resistance may be insufficient. 99.5% is a realistic upper limit.

[0024] The mass-average molecular weight (Mw) of the polypropylene constituting the base layer (A) of the polypropylene-based laminated film of the present invention is preferably 180,000 to 500,000. If the Mw is less than 180,000, the melt viscosity is low, which can lead to instability during casting and poor film formation. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less becomes 35% by mass, resulting in a deterioration of the thermal shrinkage rate at high temperatures. A more preferable lower limit for Mw is 190,000, even more preferably 200,000, and a more preferable upper limit for Mw is 320,000, even more preferably 300,000, and particularly preferably 250,000.

[0025] The number-average molecular weight (Mn) of the polypropylene constituting the base layer (A) of the polypropylene laminated film of the present invention is preferably 20,000 to 200,000. If the value is less than 20,000, the melt viscosity is low, which can lead to instability during casting and poor film formation. If it exceeds 200,000, the thermal shrinkage rate at high temperatures deteriorates. A more preferable lower limit for Mn is 30,000, even more preferably 40,000, and particularly preferably 50,000, while a more preferable upper limit for Mn is 80,000, even more preferably 70,000, and particularly preferably 60,000.

[0026] Furthermore, the Mw / Mn ratio, an indicator of molecular weight distribution, is preferably 2.8 to 10 for the polypropylene constituting the base layer (A). More preferably 2.8 to 8, even more preferably 2.8 to 6, and particularly preferably 2.8 to 5.4. The lower limit is preferably 3 or higher, and more preferably 3.3 or higher. Furthermore, the molecular weight distribution of polypropylene can be adjusted by polymerizing components of different molecular weights in a multi-stage process in a series of plants, blending components of different molecular weights offline in a kneader, polymerizing by blending catalysts with different properties, or using catalysts that can achieve the desired molecular weight distribution.

[0027] In the polypropylene laminated film of the present invention, the polypropylene constituting the base layer (A) preferably has a melt flow rate (MFR; 230°C, 2.16 kgf) of 2 g / 10 min to 20 g / 10 min when the Mw / Mn is in the range of 2.8 to 5.4. The lower limit of the MFR of the polypropylene in the base layer (A) is more preferably 3 g / 10 min, even more preferably 4 g / 10 min, and particularly preferably 5 g / 10 min. The upper limit of the MFR of the polypropylene constituting the base layer (A) is more preferably 15 g / 10 min, and even more preferably 12 g / 10 min. When the Mw / Mn and MFR of the polypropylene constituting the base layer (A) are within this range, the thermal shrinkage rate at high temperatures can be kept low, and adhesion to the cooling roll is also good, resulting in excellent film formation.

[0028] (2) Surface layer (B) The arithmetic mean roughness (Ra) of the surface of the surface layer (B) of the polypropylene laminated film of the present invention, as measured by a scanning probe microscope (AFM), is preferably 3.0 nm or more and 5.5 nm or less. The arithmetic mean roughness (Ra) is determined by using a scanning probe microscope (AFM) in dynamic mode, measuring in the X and Y directions within a range of 2 μm, correcting the obtained image (tilt, line fit, noise line removal), and then determining it according to the definition of arithmetic mean roughness described in JIS-B0601 (1994).

[0029] The arithmetic mean roughness Ra in a 2 μm square range, measured by AFM, is an indicator of the surface irregularities of the resin itself, excluding the relatively large peaks and valleys formed by antiblocking agents and lubricants, and is related to the adhesion to the inorganic thin film layer. If the arithmetic mean roughness (Ra) is less than 3.0 nm, the surface area of ​​the surface layer (B) is small, resulting in a problem of reduced adhesion. If the arithmetic mean roughness (Ra) exceeds 5.5 nm, the surface irregularities are large, causing voids during inorganic thin film formation and resulting in poor barrier properties. The arithmetic mean roughness (Ra) of the surface on the surface layer (B) side is more preferably 3.2 nm or higher, even more preferably 3.3 nm or higher, particularly preferably 3.5 nm or higher, and most preferably 4.0 nm or higher. In order to achieve an arithmetic mean roughness (Ra) of the surface layer (B) side surface of 3.0 nm or more and 5.5 nm or less, it is preferable to use a mixture of two or more polypropylene resins with different melt flow rates (MFRs) as the polypropylene resin composition forming the surface layer (B). In this case, the difference in MFRs is preferably 3 g / 10 min or more, and more preferably 3.5 g / 10 min or more. As described above, it is presumed that if the melt flow rates (MFRs) of two or more polypropylene resins in a polypropylene resin mixture differ, the crystallization rates and degrees of crystallinity of each polypropylene will differ, making it easier for surface irregularities to form. However, caution is necessary because if the degree of crystallinity of polypropylene is high, or if the cooling rate of the unstretched sheet is slow during film manufacturing, surface irregularities due to spherulites will become larger, and if the stretching temperature is too high during longitudinal or transverse stretching, whitening will occur and surface irregularities will increase, potentially exceeding an arithmetic mean roughness (Ra) of 5.5.

[0030] As a polypropylene resin with a lower MFR, polypropylene copolymerized with ethylene and / or α-olefins having 4 or more carbon atoms can also be used. Examples of α-olefins having 4 or more carbon atoms include 1-butene, 1-hexene, 4-methyl·1-pentene, and 1-octene. In addition, polar substances such as maleic acid may be used as other copolymerization components. It is preferable that the total amount of ethylene and / or α-olefins having 4 or more carbon atoms, and other copolymer components be 8.0 mol% or less. If copolymerization exceeds 8.0 mol%, the film may whiten, resulting in a poor appearance, or it may become sticky, making film formation difficult. Furthermore, these resins may be used in a blend of two or more types. When blending, the individual resins may be copolymerized in amounts exceeding 8.0 mol%, but it is preferable that the blended product contains 8.0 mol% or less of monomers other than propylene on a monomer basis. Furthermore, as the polypropylene resin with a higher MFR, either the copolymerized polypropylene mentioned above or homopolypropylene resin can be used.

[0031] Furthermore, the polypropylene resin composition constituting the surface layer (B) of the polypropylene laminated film of the present invention preferably has an MFR of 1.0 g / 10 min to 10.0 g / 10 min. The lower limit of the MFR of the polypropylene resin composition constituting the surface layer (B) is more preferably 2.0 g / 10 min, even more preferably 3.0 g / 10 min, and particularly preferably 4.0 g / 10 min. The upper limit of the MFR of the polypropylene resin composition constituting the surface layer (B) is more preferably 9.0 g / 10 min, even more preferably 8.0 g / 10 min, and particularly preferably 5.5 g / 10 min. Within this range, film-forming properties are good and the appearance is excellent. If the MFR of the polypropylene resin composition constituting the surface layer (B) is less than 1.0 g / 10 min, the viscosity difference between the base layer (A) and the surface layer (B) becomes large when the MFR of the polypropylene constituting the base layer (A) is large, making it easier for unevenness (raw material unevenness) to occur during film formation. If the MFR of the polypropylene resin composition constituting the surface layer (B) exceeds 10 g / 10 min, adhesion to the cooling roll deteriorates, air is trapped, smoothness is poor, and this can lead to many defects.

[0032] Furthermore, it is preferable that the mean center surface roughness (SRa) of the surface layer (B) of the polypropylene laminated film, measured by a 3D roughness meter, is 0.010 μm or more and 0.040 μm or less, regardless of the presence or absence of the inorganic thin film (D). The mean center surface roughness SRa is determined by using a 3D roughness meter, with a needle pressure of 20 mg, a measurement length of 1 mm in the X direction, a feed pitch of 2 μm in the Y direction, 99 recorded lines, a height magnification of 20,000 times, and a cutoff of 80 μm, and is determined in accordance with the definition of arithmetic mean roughness described in JIS-B0601 (1994). The mean center surface roughness (SRa) of the surface layer (B) is more preferably 0.012 μm or more and 0.038 μm or less, even more preferably 0.015 μm or more and 0.036 μm or less, and particularly preferably 0.020 μm or more and 0.034 μm or less. Regardless of the presence or absence of the inorganic thin film (D), if the mean center surface roughness (SRa) of the surface of the surface layer (B) is less than 0.010 μm, the surface irregularities are small, resulting in poor film slipperiness, air release time between films, and blocking resistance. If the mean center surface roughness (SRa) of the surface of the surface layer (B) exceeds 0.040 μm, when laminating the inorganic thin film layer (D), the antiblocking agent may penetrate the thin film layer, or the thin film may not form on the sides of the convex portions, resulting in reduced barrier properties and poor adhesion. There are several methods to bring the mean center surface roughness (SRa) of the surface of the surface layer (B) within the specified range, but it is possible to adjust it by changing the average particle size and amount of antiblocking agent added.

[0033] As an antiblocking agent, inorganic particles such as silica, calcium carbonate, kaolin, and zeolite, and organic particles such as acrylic, polymethacrylic, and polystyrene can be appropriately selected and used. Among these, silica and polymethacrylic particles are particularly preferred. The preferred average particle size of the antiblocking agent is 1.0 to 3.0 μm, and more preferably 1.0 to 2.7 μm. The method for measuring the average particle size here is to take a photograph with a scanning electron microscope, measure the horizontal Ferret diameter using an image analyzer, and display the average value. The addition amount of the antiblocking agent is not particularly limited as long as the addition amounts to the surface layer (B) and the surface layer (C) are adjusted so that haze, coefficient of kinetic friction, center plane average roughness (SRa), and air bleeding time are within a predetermined range.

[0034] It is preferable that the wetting tension of the surface of the surface layer (B) of the polypropylene-based laminated film of the present invention is 38 mN / m or more. The wetting tension represents the numerical value of the surface tension (mN / m) of the mixed liquid reagent determined to wet the film surface and is related to the wettability of printing ink and adhesives. When the wetting tension is 38 mN / m or more, the adhesion to the adhesive used for lamination with a vapor deposition film, a coating film, or another member film is improved. To make the wetting tension 38 mN / m or more, additives such as an antistatic agent and a surfactant are usually used. However, since these methods have the effect of lowering the surface resistance value, it is preferable to perform physicochemical surface treatments such as corona treatment and flame treatment. For example, in corona treatment, it is preferable to use a preheating roll and a treatment roll and perform discharge in the air.

[0035] The Martens hardness of the surface layer (B) of the polypropylene-based laminated film of the present invention is preferably 310 N / mm 2 or less regardless of the presence or absence of the inorganic thin film (D). The Martens hardness indicates the hardness of the resin when a needle tip with a curvature radius of 0.1 μm or less is pressed into the surface by about 0.1 μm using a dynamic ultra-micro hardness tester. Preferably, it is 305 N / mm 2 or less, and more preferably 300 N / mm 2 or less. When the Martens hardness exceeds 310 N / mm 2 the surface becomes hard, the followability of the resin surface in processing deteriorates, and the adhesion decreases. The Martens hardness is 310 N / mm 2This can be achieved by adding ethylene and / or α-olefins with 4 or more carbon atoms, or other copolymer components. Furthermore, reducing the film's stretch ratio and thereby lowering the molecular chain orientation can also reduce Martens hardness. However, caution is necessary as the film may become brittle and harden due to radiant heat during inorganic thin film formation, or harden due to bleeding of components from the substrate. The surface layer (B) of the polypropylene laminated film of the present invention has a Martens hardness of 200 N / mm². 2 Preferably, it is 210 N / mm² or higher, and more preferably 210 N / mm². 2 That's all.

[0036] (3) Surface layer (C) It is preferable that the mean center surface roughness (SRa) of the surface layer (C) of the polypropylene laminated film of the present invention, as measured by a three-dimensional roughness meter, is 0.020 μm or more. More preferably, the mean center surface roughness (SRa) of the surface layer (C) is 0.022 μm or more, even more preferably 0.025 μm or more, and particularly preferably 0.028 μm or more. If the mean center surface roughness (SRa) of the surface layer (C) is less than 0.020 μm, the surface irregularities are small, resulting in poor film slipperiness, air release time between films, and blocking resistance. There are several methods for bringing the mean center surface roughness (SRa) of the surface layer (C) within the specified range, but it is possible to adjust it by changing the average particle size and amount of antiblocking agent added. Preferably, the mean center surface roughness (SRa) of the surface layer (C) of the polypropylene laminated film of the present invention, as measured by a three-dimensional roughness meter, is 0.040 μm or less.

[0037] Furthermore, the Martens hardness of the surface layer (C) of the polypropylene laminated film is 270 N / mm². 2 Preferably, it is 275 N / mm². 2 More preferably 280 N / mm 2 The above, in particular, is preferred at 285 N / mm 2 That's all. The Martens hardness is 270 N / mm². 2If the hardness is less than 270 N / mm², the surface will be soft, and the added antiblocking agent will sink into the resin, resulting in poor lubricity and antiblocking properties. 2 To achieve the above, it is preferable to use polypropylene copolymerized with ethylene and / or α-olefins having 4 or more carbon atoms in an amount of 0.5 mol% or less, more preferably 0.1 mol% or less, and most preferably completely homopolypropylene that does not contain copolymer components. In addition, it is possible to increase the Martens hardness by increasing the degree of crystallinity by setting the mesopentade fraction ([mmmm]%) of the constituent polypropylene to 98% or more. The Martens hardness of the surface layer (C) of the polypropylene laminate film is 350 N / mm². 2 The following is preferable:

[0038] The polypropylene resin used in this invention is obtained by polymerizing the raw material propylene using known catalysts such as Ziegler-Natta catalysts or metallocene catalysts. In particular, it is preferable to use a Ziegler-Natta catalyst to eliminate heterogeneous bonding and to use a catalyst that enables polymerization with high stereoregularity. Any known method can be used to polymerize the raw material propylene. Examples include polymerization in an inert solvent such as hexane, heptane, toluene, or xylene; polymerization in a liquid monomer; polymerization in the gas phase by adding a catalyst to a gaseous monomer; or polymerization by combining these methods.

[0039] The base layer (A) and / or surface layer (B) and / or surface layer (C) of the polypropylene laminated film of the present invention may contain additives or other resins. Examples of additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, and inorganic or organic fillers. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers which are copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers. These may be polymerized sequentially using a multi-stage reactor, blended with polypropylene resin using a Henschel mixer, diluted with polypropylene to a predetermined concentration by preparing a master pellet in advance using a melt kneader, or melt-kneaded in its entirety before use. Furthermore, as long as the objective of the present invention is not impaired, corona discharge treatment, glow discharge treatment, flame treatment, surface roughening treatment may be applied, and known anchor coating treatments, printing, decoration, etc., may also be applied.

[0040] (3) Polypropylene laminated film The polypropylene laminated film of the present invention is preferably a biaxially oriented film and has a three-layer structure of surface layer (B) / substrate layer (A) / surface layer (C), but may also have a two-layer structure of surface layer (B) / substrate layer (A), a four-layer structure of surface layer (B) / substrate layer (A) / intermediate layer (D) / surface layer (C), or a multilayer structure of more than two layers. Furthermore, if there are multiple base layers (A), surface layers (B), and surface layers (C), the compositions of each layer may differ, as long as each layer satisfies its respective characteristics.

[0041] The overall thickness of the polypropylene laminated film of the present invention is preferably 9 μm or more and 200 μm or less, more preferably 10 μm or more and 150 μm or less, even more preferably 12 μm or more and 100 μm or less, and particularly preferably 15 μm or more and 80 μm or less.

[0042] In the polypropylene laminated film of the present invention, the ratio of the thickness of the surface layer (B) to the thickness of the base layer (A) is preferably 0.01 or more and 0.50 or less, more preferably 0.02 or more and 0.40 or less, even more preferably 0.03 to 0.30, and particularly preferably 0.04 or more and 0.20 or less. When the ratio of the total surface layer (B) to the total base layer (A) exceeds 0.50, the thermal shrinkage rate tends to increase.

[0043] Furthermore, regarding the ratio of the thickness of the surface layer (C) to the thickness of the base layer (A) in a polypropylene laminated film, the ratio of the total thickness of the surface layer (C) to the total thickness of the base layer (A) is preferably 0.01 or more and 0.50 or less, more preferably 0.02 or more and 0.40 or less, even more preferably 0.03 or more and 0.30 or less, and particularly preferably 0.04 or more and 0.20 or less. If the ratio of the total surface layer (C) to the total base layer (A) exceeds 0.50, the haze will increase depending on the amount of antiblocking agent added, and the transparency will deteriorate.

[0044] Furthermore, the thickness of the total substrate layer (A) relative to the total thickness of the film is preferably 50% or more and 99% or less, more preferably 60% or more and 97% or less, particularly preferably 70% or more and 95% or less, and most preferably 80% or more and 92% or less.

[0045] The haze of the polypropylene laminated film of the present invention is preferably 5% or less, regardless of the presence or absence of an inorganic thin film (D), more preferably 0.2% or more and 5.0% or less, even more preferably 0.3% or more and 4.5% or less, and particularly preferably 0.4% or more and 4.0% or less. Within this range, the film may be easier to use in applications where transparency is required. Haze tends to worsen, for example, when the stretching temperature or heat-fixing temperature is too high, when the cooling roll temperature is high and the cooling rate of the unstretched (raw) sheet is slow, or when there is too much low molecular weight component. By adjusting these factors, the haze can be kept within the above range. The method for measuring haze will be described later.

[0046] The tensile modulus of the polypropylene laminated film of the present invention is preferably 1.8 GPa or more and 4.0 GPa or less in the longitudinal direction (MD direction), more preferably 2.0 GPa or more and 3.7 GPa or less, even more preferably 2.1 GPa or more and 3.5 GPa or less, and particularly preferably 2.2 GPa or more and 3.4 GPa or less. The tensile modulus of the transverse direction (TD direction) is preferably 3.8 GPa or more and 8.0 GPa or less, more preferably 4.0 GPa or more and 7.5 GPa or less, even more preferably 4.1 GPa or more and 7.0 GPa or less, and particularly preferably 4.2 GPa or more and 6.5 GPa or less. If the tensile modulus is within the above range, the film will be stiffer and can be used even with a smaller film thickness, thus reducing the amount of film used. The method for measuring the tensile modulus will be described later.

[0047] In the polypropylene laminated film of the present invention, the longitudinal heat shrinkage rate at 150°C is preferably 0.2% or more and 15.0% or less, more preferably 0.3% or more and 13.0% or less, even more preferably 0.5% or more and 11.0% or less, and particularly preferably 0.5% or more and 9.0% or less. If the heat shrinkage rate is within the above range, the film can be said to have excellent heat resistance and can be used in applications where it may be exposed to high temperatures. It should be noted that a heat shrinkage rate of up to about 1.5% at 150°C can be achieved, for example, by increasing the amount of low molecular weight components, adjusting the stretching conditions, and adjusting the heat setting conditions, but to reduce it below that, it is preferable to perform an offline annealing treatment. In the polypropylene laminated film of the present invention, the transverse heat shrinkage rate at 150°C is preferably 0.5% or more and 30.0% or less, more preferably 0.5% or more and 25.0% or less, even more preferably 0.5% or more and 20.0% or less, and particularly preferably 0.5% or more and 18.0% or less. If the heat shrinkage rate is within the above range, the film can be said to have excellent heat resistance and can be used in applications where it may be exposed to high temperatures. It should be noted that a heat shrinkage rate of up to about 1.5% at 150°C can be achieved, for example, by increasing the amount of low molecular weight components, adjusting the stretching conditions, and adjusting the heat setting conditions, but to reduce it below that, it is preferable to perform an offline annealing treatment.

[0048] The coefficient of dynamic friction in the surface layers (B) and (C) of the polypropylene laminated film of the present invention is preferably 0.60 or less, more preferably 0.55 or less, and particularly preferably 0.50 or less. A coefficient of dynamic friction of 0.60 or less allows for smooth unwinding of the film from the roll film, making it easy to print and process.

[0049] The air release time between surface layers (B) and (C) of the polypropylene laminated film of the present invention is preferably 10 seconds or less, more preferably 8 seconds or less, and even more preferably 5 seconds or less. If the air release time exceeds 10 seconds, the air will escape slowly when the film is rolled up, and wrinkles will easily form.

[0050] (4) Manufacturing method The polypropylene laminated film of the present invention is preferably a biaxially oriented film, and can be obtained by melt-extruding the polypropylene resin composition constituting the base layer (A), the polypropylene resin composition constituting the surface layer (B), and the polypropylene resin composition constituting the surface layer (C) using separate extruders, co-extruding them from a die, cooling them with a cooling roll to form an unstretched sheet, stretching the unstretched sheet in the longitudinal (MD) and transverse (TD) directions, and then performing a heat-setting treatment. It is preferable to extrude the film so that the surface layer (B) is in contact with the cooling roll. If the surface layer (B) is on the opposite side from the side in contact with the cooling roll, the polypropylene resin will cool slowly, the degree of crystallinity will increase, and the arithmetic mean roughness (Ra) of the surface of the surface layer (B) may become too large due to surface irregularities caused by spherulites. The melt extrusion temperature is preferably around 200 to 280°C. To obtain a laminated film with a good appearance without disturbing the layers within this temperature range, it is preferable that the viscosity difference (MFR difference) between the polypropylene raw material for the base layer (A) and the polypropylene raw material for the surface layer (B) be 6.0 g / 10 min or less. If the viscosity difference is greater than 6 g / 10 min, the layers tend to be disturbed, resulting in a poor appearance. The viscosity difference is more preferably 5.5 g / 10 min or less, and even more preferably 5.0 g / 10 min or less.

[0051] The cooling roll surface temperature is preferably 25 to 35°C, and more preferably 27 to 33°C. If the cooling roll temperature exceeds 35°C, the degree of crystallinity of the polypropylene resin increases, and the surface irregularities caused by the formed spherulites may cause the arithmetic mean roughness (Ra) of the surface of the surface layer (B) to become too large.

[0052] The lower limit of the stretching ratio in the longitudinal direction (MD) is preferably 3 times, more preferably 3.5 times. If it is less than the above, uneven film thickness may occur. The upper limit of the stretching ratio in the MD is preferably 8 times, more preferably 7 times. If it exceeds the above, subsequent TD stretching may become difficult. The lower limit of the stretching temperature in the MD is preferably 120°C, more preferably 125°C, and even more preferably 130°C. If it is less than the above, the mechanical load may increase, thickness unevenness may increase, or surface roughness of the film may occur. The upper limit of the stretching temperature in the MD is preferably 160°C, more preferably 155°C, and even more preferably 150°C. Higher temperatures are preferable for reducing the thermal shrinkage rate, but the film may stick to the roll and become impossible to stretch, or surface roughness may occur.

[0053] The lower limit of the stretching ratio in the width direction (TD) is preferably 4 times, more preferably 5 times, and even more preferably 6 times. If it is less than the above, thickness unevenness may occur. The upper limit of the TD stretching ratio is preferably 20 times, more preferably 17 times, even more preferably 15 times, and particularly preferably 12 times. If it exceeds the above, the thermal shrinkage rate may increase or the film may break during stretching. The preheating temperature for TD stretching is preferably set 5 to 15°C higher than the stretching temperature in order to quickly raise the film temperature to around the stretching temperature. The lower limit of the TD stretching temperature is preferably 150°C, more preferably 155°C, even more preferably 158°C, and particularly preferably 160°C. If it is less than the above, the film may break without softening sufficiently or the thermal shrinkage rate may increase. The upper limit of the TD stretching temperature is preferably 170°C, more preferably 168°C, and even more preferably 165°C. While higher temperatures are preferable to reduce thermal shrinkage, exceeding the above temperature can cause low-molecular-weight components to melt and recrystallize, leading to a decrease in orientation, as well as surface roughness and whitening of the film.

[0054] The stretched film is heat-set. The lower limit of the heat-set temperature is preferably 163°C, and more preferably 165°C. Below this temperature, the heat shrinkage rate may be high. Also, a long processing time may be required to reduce the heat shrinkage rate, which may reduce productivity. The upper limit of the heat-set temperature is preferably 176°C, and more preferably 175°C. Above this temperature, low molecular weight components may melt and recrystallize, causing surface roughness or whitening of the film.

[0055] It is preferable to relax the material during heat setting. The lower limit of the relaxation rate is preferably 2%, and more preferably 3%. If it is less than the above, the thermal shrinkage rate may increase. The upper limit of the relaxation rate is preferably 10%, and more preferably 8%. If it exceeds the above, thickness unevenness may increase.

[0056] Furthermore, to reduce the thermal shrinkage rate, the film manufactured in the above process can be wound into a roll and then annealed offline.

[0057] The biaxially oriented polypropylene laminated film thus obtained can be subjected to corona discharge, plasma treatment, flame treatment, etc., as needed, and then wound up with a winder to obtain the biaxially oriented polypropylene film roll of the present invention.

[0058] [Inorganic thin film layer] The gas barrier laminated film of the present invention has an inorganic thin film layer on the surface of the base film layer. The inorganic thin film layer is a thin film made of a metal or an inorganic oxide. The material forming the inorganic thin film layer is not particularly limited as long as it can be made into a thin film, but from the viewpoint of gas barrier properties, inorganic oxides such as silicon dioxide (silica), aluminum oxide (alumina), and mixtures of silicon dioxide and aluminum oxide are preferred. In this composite oxide, the mixing ratio of silicon dioxide and aluminum oxide is preferably in the range of 20 to 70% by mass of Al in terms of the mass ratio of the metal content. If the Al concentration is less than 20% by mass, the water vapor barrier properties may be low. On the other hand, if it exceeds 70% by mass, the inorganic thin film layer tends to harden, and there is a risk that the film will be destroyed during secondary processing such as printing or lamination, reducing the gas barrier properties. Also, when the Al concentration is 100% by mass, the water vapor barrier performance is good, but because it is a single material, the surface tends to be smooth, resulting in poor slipperiness and making it prone to processing defects (wrinkles, blemishes, etc.). In this context, silicon oxide refers to various silicon oxides such as SiO and SiO2, or mixtures thereof, while aluminum oxide refers to various aluminum oxides such as AlO and Al2O3, or mixtures thereof.

[0059] The thickness of the inorganic thin film layer is typically 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, if the thickness is excessively increased beyond 100 nm, the corresponding improvement in gas barrier properties cannot be obtained, and it may even be disadvantageous in terms of flexibility and manufacturing costs.

[0060] There are no particular restrictions on the method for forming an inorganic thin film layer; for example, any known deposition method such as vacuum deposition, sputtering, ion plating (physical vapor deposition methods (PVD)), or chemical vapor deposition (CVD) can be used as appropriate. Below, a typical method for forming an inorganic thin film layer will be described using a silicon oxide / aluminum oxide thin film as an example. For example, when using vacuum deposition, a mixture of SiO2 and Al2O3, or a mixture of SiO2 and Al, is preferably used as the deposition raw material. These deposition raw materials are usually particles, and it is desirable that the size of each particle is such that the pressure during deposition does not change, with a preferred particle size of 1 mm to 5 mm. For heating, methods such as resistance heating, high-frequency induction heating, electron beam heating, and laser heating can be used. It is also possible to use reactive deposition by introducing oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, etc. as a reaction gas, or by using means such as ozone addition or ion assistance. Furthermore, the film formation conditions can be arbitrarily changed, such as by applying a bias to the substrate (laminated film to be deposited) or by heating or cooling the substrate. These deposition materials, reaction gases, bias of the deposition target, heating / cooling, etc., can be similarly modified when using sputtering or CVD methods.

[0061] The laminated film of the present invention requires that the water contact angle of the inorganic thin film layer (D) surface be 75° or less. Preferably, it is 10° or more and 70° or less, more preferably 15° or more and 65° or less, and even more preferably 20° or more and 60° or less. The water contact angle is an indicator of the film quality of the inorganic thin film layer. By setting the water contact angle within the above range, water-resistant adhesion and good barrier performance can be achieved. If the water contact angle is less than 10°, the film becomes hydrophilic, which may worsen the water vapor barrier performance. Furthermore, the hydrophilic surface reduces adhesion to the substrate, making it easier for water to penetrate between layers, and tending to reduce water-resistant adhesion. On the other hand, if the water contact angle is greater than 75°, the inorganic film cannot be said to be uniformly formed, and the barrier performance deteriorates.

[0062] The water contact angle of the inorganic thin film layer (D) surface depends on the material used for the inorganic thin film layer. Regarding the material, it is preferable that the concentration of aluminum or aluminum oxide in the inorganic thin film layer (D) is 30% by mass or more. More preferably, it is 35% by mass or more, and even more preferably 40% by mass or more. If the aluminum oxide concentration is less than 30% by mass, the film becomes hydrophilic, and the aforementioned water contact angle falls below the lower limit.

[0063] The inventors have found that the water contact angle of the inorganic thin film layer (D) surface is also affected by the surface resistance of the substrate (degree of exposure of the antistatic agent). The antistatic agent has hydrophilic parts such as hydrophilic groups to exhibit an antistatic effect, and it was predicted that when the antistatic agent is exposed (bleed-out) on the surface layer (B), the water contact angle of the inorganic thin film layer (D) surface would be smaller than when the antistatic agent is not present. However, it was found that the exposure of the antistatic agent actually increases the water contact angle of the inorganic thin film layer (D) surface. In the present invention, the surface resistance of the surface layer (B) of the substrate film is preferably 14LogΩ or higher. When the surface resistance is 14LogΩ or higher, there is less exposure of the antistatic agent that inhibits the lamination of the inorganic thin film layer (D), so it can be laminated uniformly and the barrier properties are improved. In this case, the water contact angle of the inorganic thin film layer (D) is within a predetermined range. The surface resistance is more preferably 15LogΩ or higher, and particularly preferably 16LogΩ or higher. If the surface resistance is less than 14 LogΩ, the antistatic agent bleeding onto the surface layer (B) will inhibit the lamination of the inorganic thin film layer (D), resulting in a non-uniform film. In this case, the water contact angle may exceed the upper limit as a result of being affected by the surface of the underlying substrate. To achieve a surface resistance of 14 LogΩ or higher, it is advisable to minimize the use of additives such as antistatic agents and anti-fogging agents. Furthermore, it is important to note that additives contained in the substrate layer (A) may bleed onto the surface of the surface layer (B).

[0064] Furthermore, the water contact angle value on the inorganic thin film layer (D) surface is also affected by the fine surface irregularities. By controlling the arithmetic mean roughness (Ra) of the inorganic thin film layer (D) side of the laminated film, as measured by a scanning probe microscope (AFM), within a predetermined range, the contact angle value can be finely adjusted.

[0065] The laminated film of the present invention preferably has an arithmetic mean roughness (Ra) of the surface on the inorganic thin film layer (D) side, measured by a scanning probe microscope (AFM), of 4.5 nm or more and 9.0 nm or less. This arithmetic mean roughness Ra follows approximately the same trend as the roughness of the surface layer (B) of the substrate film described above, but the inventors have found that the roughness changes further after the inorganic thin film layer is formed. The reason for this is not clear, but it is thought that during the inorganic thin film lamination process, heat is applied to the film, causing changes in the surface irregularities of the substrate resin, and furthermore, low molecular weight components and additives such as antistatic agents appear from the substrate, resulting in an effect on the surface irregularities. If the arithmetic mean roughness (Ra) is within the above range, not only is the adhesion between the inorganic thin film layer and the substrate improved, but by forming larger surface irregularities, the adhesion when further laminated protective layers, adhesives, or printed layers can also be maintained. If the arithmetic mean roughness (Ra) is less than 4.5 nm, the surface area is small and the adhesion strength decreases, which is a problem. If the arithmetic mean roughness (Ra) exceeds 9.0 nm, the surface will be uneven and have large surface irregularities, which may reduce adhesion. The arithmetic mean roughness (Ra) of the inorganic thin film layer (D) side surface is more preferably 4.7 nm or higher, even more preferably 4.9 nm or higher, particularly preferably 5.1 nm or higher, and most preferably 5.3 nm or higher. To achieve an arithmetic mean roughness (Ra) of the inorganic thin film layer (D) side surface of 0.4.5 nm or more and 9.0 nm or less, in addition to setting the arithmetic mean roughness (Ra) of the substrate film surface layer (B) within the aforementioned preferred range, adjustments can be made by changing the presence or absence of additives derived from the substrate, the film cooling conditions during the inorganic thin film formation process, and the thin film material, composition, and film thickness. [Protective layer] In the present invention, a protective layer may be provided on the inorganic thin film layer (D) if further gas barrier performance is required or if processing such as printing is necessary. The inorganic thin film layer is not a completely dense film, but has minute defects scattered throughout. By coating the inorganic thin film layer with a specific protective layer resin composition described later to form a protective layer, the resin in the protective layer resin composition penetrates into the defects in the inorganic thin film layer, resulting in the effect of stabilizing the gas barrier properties. In addition, by using a material that also has gas barrier properties for the protective layer itself, the gas barrier performance of the laminated film is greatly improved. However, it is necessary to note that providing a protective layer increases costs due to the increased number of processes and may have an environmental impact depending on the materials used. It is also necessary to note that the protective layer may change physical properties such as surface roughness.

[0066] The amount of protective layer adhering is 0.10 to 1.00 (g / m²). 2 It is preferable to have a protective layer of 0.13 g / m². This allows for uniform control of the protective layer during coating, resulting in a film with fewer coating inconsistencies and defects. Furthermore, the cohesive force of the protective layer itself is improved, and the adhesion between the inorganic thin film layer and the protective layer becomes stronger. The amount of protective layer attached is preferably 0.13 g / m². 2 ) or more, more preferably 0.16 (g / m³) 2 ) or more, more preferably 0.19 (g / m³) 2 ) or more, preferably 0.0.97 (g / m³) 2 ) or less, more preferably 0.94 (g / m³) 2 ) or less, more preferably 0.91 (g / m³) 2 ) or less. The amount of protective layer adhered is 1.00 (g / m²). 2 When the thickness exceeds 0.10 (g / m²), the gas barrier properties improve, but the cohesive force within the protective layer becomes insufficient, and the uniformity of the protective layer also decreases, which may result in unevenness or defects in the appearance of the coating, or insufficient gas barrier properties and adhesion. On the other hand, when the thickness of the protective layer exceeds 0.10 (g / m²), the gas barrier properties improve, but the cohesive force within the protective layer becomes insufficient, and the uniformity of the protective layer also decreases, which may result in unevenness or defects in the appearance of the coating, or insufficient gas barrier properties and adhesion. 2 If the value is less than ), sufficient gas barrier properties and interlayer adhesion may not be obtained.

[0067] Examples of resin compositions used for the protective layer formed on the surface of the inorganic thin film layer (D) of the laminated film of the present invention include resins such as vinyl alcohol-based, urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins to which curing agents such as epoxy-based, isocyanate-based, and melamine-based resins are added.

[0068] The coating method for the protective layer resin composition is not particularly limited as long as it is a method of coating the film surface to form a layer. For example, conventional coating methods such as gravure coating, reverse roll coating, wire bar coating, and die coating can be used.

[0069] When forming a protective layer, it is preferable to apply the protective layer resin composition and then heat-dry it, with a preferred drying temperature of 100 to 160°C, more preferably 105 to 155°C, and even more preferably 110 to 150°C. If the drying temperature is below 100°C, the protective layer may not dry sufficiently, or the protective layer may not form properly, reducing its cohesive strength and water-resistant adhesion, which may result in reduced barrier properties and tear resistance. On the other hand, if the drying temperature exceeds 160°C, the film may become too hot, making it brittle, reducing its puncture strength, or shrinking, resulting in poor processability. In particular, drying at 100°C or higher, preferably 110°C or higher, allows the protective layer to form effectively, increasing the adhesion area between the protective layer resin and the inorganic thin film layer, thereby improving water-resistant adhesion. It is particularly preferable to first evaporate the solvent at a relatively low temperature of about 90°C immediately after application, and then dry the protective film at 100°C or higher, as this results in a uniform film. In addition to drying, applying an extra heat treatment at the lowest possible temperature is even more effective in promoting the formation of the protective layer.

[0070] [Packaging materials] When the laminated film of the present invention is used as a packaging material, it is preferable to form a laminate with a heat-sealable resin layer called a sealant. The heat-sealable resin layer is usually provided on an inorganic thin film layer, but it may also be provided on the outside of the base film layer (the side opposite the inorganic thin film formation surface). The heat-sealable resin layer is usually formed by extrusion lamination or dry lamination. As the thermoplastic polymer that forms the heat-sealable resin layer, any polymer that can exhibit sufficient sealant adhesion is acceptable, but polyethylene resins such as olefin-based HDPE, LDPE, LLDPE, polypropylene resin, ethylene-vinyl acetate copolymer, ethylene-α-olefin random copolymer, ionomer resin, etc. can be used. Among these, LLDPE or polypropylene resin is particularly preferred because it is highly versatile from the viewpoint of durability, seal strength, cost, and monomaterialization. The thickness of the sealant layer is preferably 20 to 100 μm, more preferably 30 to 90 μm, and more preferably 40 to 80 μm. If the thickness is thinner than 20 μm, sufficient seal strength may not be obtained, and it may be difficult to handle due to a lack of stiffness. On the other hand, if the thickness exceeds 100 μm, the material becomes too stiff, reducing its handling properties as a bag, and the price may also increase.

[0071] [Adhesive layer] The adhesive layer used in this invention can be a general-purpose laminating adhesive. For example, solvent-free, water-based, or heat-melt adhesives mainly composed of poly(ester)urethane, polyester, polyamide, epoxy, poly(meth)acrylic, polyethyleneimine, ethylene-(meth)acrylic acid, polyvinyl acetate, (modified) polyolefin, polybutadiene, wax, casein, etc., can be used. Among these, urethane or polyester adhesives are preferred considering heat resistance and flexibility to follow dimensional changes of each substrate. As for the lamination method of the adhesive layer, for example, it can be applied by direct gravure coating, reverse gravure coating, kiss coating, die coating, roll coating, dip coating, knife coating, spray coating, fontein coating, or other methods, and the coating amount after drying is preferably 1 to 8 g / m2, more preferably 2 to 7 g / m2, in order to achieve sufficient adhesion. 2 More preferably 3-6 g / m 2 The coating amount is 1 g / m². 2 If the amount is less than 8 g / m², it becomes difficult to bond the entire surface, and the adhesive strength decreases. 2 Beyond this point, complete curing of the film takes longer, unreacted material is more likely to remain, and the adhesive strength decreases.

[0072] Furthermore, the laminated film of the present invention may have at least one printed layer or other plastic substrate and / or paper substrate laminated between or outside the base film layer and the heat-sealable resin layer.

[0073] Water-based and solvent-based resin-containing printing inks are preferably used as the printing ink for forming the printed layer. Examples of resins used in the printing ink 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, defoaming agents, crosslinking agents, anti-blocking agents, and antioxidants. The printing method for forming the printed layer is not particularly limited, and known printing methods such as offset printing, gravure printing, and screen printing can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot roll drying, and infrared drying can be used.

[0074] The laminated film of the present invention has an oxygen permeability of 60 cc / m² under conditions of 23°C × 65% RH. 2 A value of d·atm or less is preferable in terms of exhibiting good gas barrier properties. More preferably 50 cc / m³ 2 d·atm or less, more preferably 40cc / m 2 It can be set to d·atm or less. Oxygen permeability of 60 cc / m³ 2 Above d·atm, it becomes difficult to meet the requirements for applications demanding high gas barrier properties. On the other hand, if the oxygen permeability is 0.1 cc / m³ in all cases... 2 If the oxygen permeability is less than d·atm, although the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, and the amount transferred to the contents may increase relatively, which is undesirable. The preferred lower limit for oxygen permeability is 0.1 cc / m³. 2 It is d·atm or more.

[0075] The laminates of the present invention all exhibit a water vapor transmission rate of 4.0 g / m² under 40°C × 90% RH conditions. 2 A value of d or less is preferable in terms of exhibiting good gas barrier properties. More preferably 3.5 g / m 2 • d or less, more preferably 3.0 g / m 2 It can be less than or equal to d. Water vapor transmission rate of 4.0 g / m³ 2If the value exceeds d, it becomes difficult to meet the requirements for applications that demand high gas barrier properties. On the other hand, if the water vapor transmission rate is 0.1 g / m³ in all cases, it becomes difficult to meet the requirements for applications that require high gas barrier properties. 2 If the value is less than 0.1 g / m³, while the barrier performance is excellent, residual solvent will not easily permeate to the outside of the bag, which may relatively increase the amount transferred to the contents, so this is undesirable. The preferred lower limit for water vapor permeability is 0.1 g / m³. 2 It is d or higher.

[0076] When the oxygen permeability value of the laminated film of the present invention measured under 23°C × 65%RH conditions is (A) and the oxygen permeability value measured under 23°C × 80%RH conditions is (B), it is preferable that the rate of deterioration of the barrier value under high temperature and high humidity conditions, expressed by the following formula, is 130% or less. More preferably, it is 125% or less, and even more preferably, 120% or less. If the rate of deterioration is greater than 130%, the barrier performance may deteriorate under high humidity, which is undesirable because it limits the usage environment and applications. Barrier value deterioration rate (%) under high temperature and high humidity conditions = (B / A) × 100 (Equation 1)

[0077] The laminates of the present invention preferably have a laminate strength of 1.5 N / 15 mm or more under 23°C × 65% RH conditions, more preferably 2.0 N / 15 mm or more, and even more preferably 2.5 N / 15 mm or more. If the laminate strength is less than 1.5 N / 15 mm, delamination may occur due to bending load or heat during sealing, potentially degrading the barrier properties or causing leakage of contents. Furthermore, the tearability may also deteriorate. [Examples]

[0078] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. The films were evaluated by the following measurement method.

[0079] [Physical properties of the base film] (1) Mesopentadione fraction ([mmmm] unit: %) The mesopentade fraction was measured using 13C-NMR. The mesopentade fraction was calculated according to the method described in "Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973)". For 13C-NMR measurement, a BRUKER AVANCE500 was used, in which 200 mg of the sample was dissolved at 135°C in an 8:2 (volume ratio) mixture of o-dichlorobenzene and deuterated benzene, and then measured at 110°C.

[0080] (2) Meltflow rate ([MFR]g / 10 min) Measurements were taken 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 simply weighed out and used. In the case of film, after cutting out the required amount, a sample cut into approximately 5mm squares was used.

[0081] (3) 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) based on monodisperse polystyrene. The measurement conditions, including the column and solvent used in the GPC measurement, are as follows. Solvent: 1,2,4-Trichlorobenzene Column: TSKgel GMHHR-H(20)HT×3 Flow rate: 1.0ml / min Detector: RI Measurement temperature: 140℃

[0082] The number-average molecular weight (Mn), mass-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) are defined by the following equations, each based on the number of molecules (Ni) of molecular weight (Mi) at each elution position of the GPC curve obtained via the molecular weight calibration curve. Number average molecular weight: Mn=Σ(Ni·Mi) / ΣNi Mass average molecular weight: Mw=Σ(Ni·Mi 2 ) / Σ(Ni·Mi) Molecular weight distribution: Mw / Mn When the baseline was not clearly defined, the baseline was set within the range from the lowest point of the high molecular weight side of the elution peak closest to the elution peak of the standard substance to the lowest point of the high molecular weight side of the tail.

[0083] (4) Melting peak temperature (°C), melting peak area (J / g) A differential scanning calorimeter (DSC) manufactured by SII was used, with a sample volume of 10 mg and a heating rate of 20 °C / min. The melting endothermic peak temperature and melting peak area were determined from the DSC curve.

[0084] (5) Thickness (μm) The thickness of each layer, the base layer (A) and the surface layer (B), was measured by microtomizing a cross-section of a biaxially oriented laminated polypropylene film solidified with modified urethane resin and observing it with a differential interference microscope.

[0085] (6) Tensile modulus (GPa) Measurements were taken in accordance with JIS K 7127. Samples measuring 10 mm in width and 180 mm in length were cut from the film using a razor blade in both the longitudinal and lateral directions. After being left for 12 hours in an atmosphere of 23°C and 65% RH, measurements were taken in an atmosphere of 23°C and 65% RH, with a chuck distance of 100 mm and a tensile speed of 200 mm / min. The average value of five measurement results was used. A Shimadzu Autograph AG5000A was used as the measuring instrument.

[0086] (7) Thermal shrinkage rate (%) The following measurements were taken in accordance with JIS Z1712. The film was cut to a width of 20 mm and a length of 200 mm in both the MD and TD directions, and then suspended in a 150°C hot air oven and heated for 5 minutes. The length was measured before and after heating, and the ratio (%) of the length after heating to the length before heating was calculated to determine the thermal shrinkage rate.

[0087] (8) Wetting tension (mN / m) Following K 6768:1999, the film was aged for 24 hours at 23°C and 50% relative humidity, and then the corona-treated surface of the film was measured using the following procedure. Step 1) Measurements are performed in a standard test room atmosphere with a temperature of 23°C and a relative humidity of 50% (see JIS K 7100). Step 2) Place the test specimen on the substrate of the hand coater (4.1), drop a few drops of the test mixture onto the specimen, and immediately pull the wire bar to spread it out. When spreading the test mixture using a cotton swab or brush, spread the liquid quickly over an area of ​​at least 6 cm². The amount of liquid should be just enough to form a thin layer, without creating puddles. The wetting tension is determined by observing the liquid film of the test mixture in a well-lit area and checking its condition after 3 seconds. If the liquid film does not break and maintains its state after 3 seconds or more, it is considered wet. If the wettiness is maintained for 3 seconds or more, proceed to the next liquid mixture with higher surface tension. Conversely, if the liquid film breaks in less than 3 seconds, proceed to the next liquid mixture with lower surface tension. Repeat this process to select a mixture that can accurately wet the surface of the test specimen in 3 seconds. Step 3) Use a new cotton swab for each test. Brushes or wire bars should be washed with methanol and dried after each use, as residual liquid can change their composition and surface tension due to evaporation. Step 4) The procedure of selecting a mixture that can wet the surface of the test specimen in 3 seconds is performed at least three times. The surface tension of the mixture thus selected is reported as the wetting tension of the film.

[0088] (9) Surface resistance (LogΩ) In accordance with JIS K6911, the surface resistance of the film's surface layer (B) was measured after aging the film at 23°C for 24 hours.

[0089] (10) Air release time (seconds) As shown in Figure 1, the film 4 is placed on the base plate 1. Next, the film retainer 2 is placed on top of the film 4 and fixed in place, applying tension to secure the film 4. Then, the film 5 is placed on top of the film retainer 2, with the side opposite to the top surface of the film 4 placed on the base plate 1 facing downwards. Next, the film retainer 8 is placed on top of the film 5, and the film retainers 8 and 2 and the base plate 1 are further secured using screws 3. Next, the cavity 2a in the film holder 2 and the vacuum pump 6 are connected via the pores 2c and pipe 7 provided in the film holder 2. When the vacuum pump 6 is driven, tension is applied to the film 5 as it is drawn to the cavity 2a. At the same time, the overlapping surfaces of film 4 and film 5 are also depressurized through the circumferentially arranged pores 2d in the film holder 2, and film 4 and film 5 begin to adhere tightly to each other from the outer edges at their overlapping surfaces. The degree of adhesion can be easily observed by observing interference fringes from the upper part of the overlapping surfaces. The time (in seconds) from when interference fringes appear on the outer edge of the overlapping surface of film 4 and film 5 until the interference fringes spread to the front of the overlapping surface and their movement stops is measured, and this time (in seconds) is defined as the air release time. The measurement is repeated five times with the two films swapped, and the average value is used. In other words, the shorter the time (in seconds), the better the winding characteristics of the film.

[0090] (11) Roll wrinkle evaluation The prepared base film was wound to a width of 500 mm and a length of 1000 m, and the wrinkles on the surface of the roll were visually evaluated according to the following criteria. A rating of ○ or △ was considered acceptable. ○: No wrinkles △: There are slight wrinkles, but they disappear when tension of about 20 N / m is applied to the pulled-out film. ×: There are strong wrinkles, and even applying a tension of about 20 N / m to the pulled-out film does not make the wrinkles disappear.

[0091] [Physical properties of laminated films after inorganic thin film lamination] (12) Haze (%) Measurements were taken at 23°C in accordance with JIS K 7105. A haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., 300A) was used. Two measurements were taken, and the average value was calculated.

[0092] (13) Composition and film thickness of inorganic thin film layer The film thickness composition of the laminated films (after thin film lamination) obtained in the examples and comparative examples was measured using a fluorescent X-ray analyzer (Rigaku Corporation's "ZSX100e") according to a pre-prepared calibration curve. The excitation X-ray tube conditions were set to 50kV and 70mA.

[0093] (14) Martens hardness (N / mm 2 ) The obtained laminated film was cut into approximately 2 cm squares, and the opposite side of the measurement surface was fixed to a glass plate approximately 1 mm thick with adhesive. The sample was then left in an atmosphere of 23°C and 50% RH for 12 hours to allow it to adjust to humidity. This sample was measured using a dynamic ultramicrohardness tester ("DUH-211" manufactured by Shimadzu Corporation) in accordance with ISO 14577-1 (2002) under the following measurement conditions. The measurement was performed 10 times with the film in a different position, and the average value of the 8 points excluding the maximum and minimum values ​​was calculated.

[0094] <Measurement conditions> (setting) • Measurement environment: Temperature 23°C, relative humidity 50% • Test mode: Load-unload test ·Indenter used: ridge angle 115 degrees, triangular pyramid indenter • Indenter modulus: 1.140 × 10⁶ N / mm² • Indenter Poisson ratio: 0.07 • Cf-Ap, As correction: Yes (conditions) • Test force: 0.10 mN ·Load speed: 0.0050mN / sec ·Load holding time: 5sec ·Unloading holding time: 0sec

[0095] (15) Center surface average roughness ([SRa]μm) The average center surface roughness (SRa) of the obtained laminated film was measured using a three-dimensional roughness meter (Kosaka Laboratory Co., Ltd., model ET-30HK) with a needle pressure of 20 mg, a measurement length of 1 mm in the X direction, a feed rate of 100 μm / sec, a feed pitch of 2 μm in the Y direction, 99 recorded lines, a height magnification of 20,000 times, and a cutoff of 80 μm. The arithmetic mean roughness was calculated according to the definition of arithmetic mean roughness described in JIS-B0601 (1994). Arithmetic mean roughness (SRa) was evaluated by taking three trials and using the average value.

[0096] (16) Arithmetic mean roughness ([Ra]nm) The arithmetic mean roughness (Ra) of the obtained laminated films was measured using a scanning probe microscope (Shimadzu Corporation "SPM-9700"). Measurements were taken in dynamic mode with measurement lengths of 2 μm in both the X and Y directions. After correcting the obtained images (tilt, line fit, noise line removal), the arithmetic mean roughness was calculated according to the definition of arithmetic mean roughness described in JIS-B0601 (1994).

[0097] (17) Water contact angle of inorganic thin film layer (D) For the laminated films (after inorganic thin film lamination) obtained in the examples and comparative examples, water was dropped onto them using a contact angle meter (model: CAM200, sold by Altec Alto Co., Ltd., manufactured by KSV Instruments, Finland), and the contact angle was measured. The contact angle was read 5 seconds after water was dropped onto the film. FAMAS (Kyowa Interface Science Co., Ltd.) was used for analysis software. The detailed measurement conditions are shown below. Temperature and humidity: 23℃, 65% Measurement method: Liquid application method (θ / 2 method) Droplet size: 7.0 μL Needle thickness: 22G, inner diameter 0.4mm

[0098] (18) Method for evaluating oxygen permeability In each example and comparative example, the laminated films obtained at the stage of laminating an inorganic thin film layer (D) onto a base film, and the laminated bodies described later, were used as samples. The oxygen permeability was measured in accordance with JIS-K7126 B method using an oxygen permeability measuring device (MOCON's "OX-TRAN(registered trademark) 1 / 50") in an atmosphere of 23°C and 65%RH or 80%RH humidity. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side to the inorganic thin film layer side.

[0099] (19) Method for evaluating water vapor transmission In each example and comparative example, the laminated films obtained at the stage of laminating an inorganic thin film layer (D) onto a base film, as well as the laminated laminates described later, were used as samples. The water vapor transmission rate was measured in accordance with JIS-K7129 Method B using a water vapor transmission rate analyzer (MOCON "PERMATRAN-W 3 / 33MG") under an atmosphere of 40°C and 90% RH. The water vapor transmission rate was measured in the direction in which water vapor permeated from the base film side to the inorganic thin film layer side.

[0100] [Fabrication of laminated structures] A polyurethane adhesive (TM569 / catRT37, manufactured by Toyo Morton Co., Ltd.) was applied to the laminates obtained in the Examples and Comparative Examples to a thickness of 3 μm after drying at 80°C. Then, an unstretched polypropylene film (P1128, manufactured by Toyobo; 30 μm thick; referred to as CPP) was dry-laminated on a metal roll heated to 60°C, and aged at 40°C for 4 days to obtain a laminate gas barrier laminate for evaluation (hereinafter sometimes referred to as "laminated laminate a").

[0101] (20) Method for evaluating laminate strength The laminated material prepared as described above was cut into 15 mm wide and 200 mm long specimens to form test pieces. The laminate strength was measured using a Tensilon universal material tester (Tensilon UMT-II-500 model, manufactured by Toyo Baldwin Co., Ltd.) under conditions of 23°C and 65% relative humidity. The laminate strength was measured at a tensile speed of 200 mm / min, and the laminated film layer and heat-sealable resin layer of each laminated film obtained in the examples and comparative examples were peeled at a peeling angle of 90 degrees. The strength was measured both when water was applied to the peeled area with a dropper (wet application) and when water was not applied (dry application).

[0102] (Raw material resin / base film) Tables 1-3 show the details of the polypropylene resin raw materials used in the following examples and comparative examples, as well as the conditions for forming the base film.

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] (Examples 1 and 6, Comparative Examples 2 and 3) For the base layer (A), the polypropylene homopolymer PP-1 shown in Table 1 was used. Furthermore, the surface layer (B) used was a mixture of 43.2% by weight of polypropylene homopolymer PP-1 shown in Table 1, 52.0% by weight of ethylene copolymer polypropylene polymer PP-3 shown in Table 1, and 4.8% by weight of masterbatch A shown in Table 2. At this time, the melt flow rate (g / 10 min) of the polypropylene resin composition constituting the surface layer (B) was 5.1. For the surface layer (C), a mixture of PP-1, a polypropylene homopolymer shown in Table 1, in a ratio of 93.6% by weight, and masterbatch A, shown in Table 2, in a ratio of 6.4% by weight, was used. The base layer (A) was produced 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 resin was melted at 250°C in each case, and co-extruded into a sheet from a T-die. After cooling and solidifying so that the surface layer (B) was in contact with a cooling roll at 30°C, the film was stretched 4.5 times in the longitudinal direction (MD) at 125°C. Next, in a tenter, both ends in the width direction (TD) of the film were clamped with clips, preheated to 168°C, stretched 8.2 times in the width direction (TD) at 155°C, and then heat-set at 165°C while relaxing by 6.7% in the width direction (TD). The film formation conditions at this time were designated as film formation condition a. Thus, a biaxially oriented polypropylene film with a surface layer (B) / substrate layer (A) / surface layer (C) configuration was obtained. The surface of the biaxially oriented polypropylene film surface layer (B) was corona treated using a corona treatment machine manufactured by Softal Corona and Plasma GmbH at an applied current of 0.75 A, and then wound up with a winder. The thickness of the resulting film was 20 μm (the thicknesses of the surface layer (B) / substrate layer (A) / surface layer (C) were 1.3 μm / 17.7 μm / 1.0 μm).

[0107] (Example 2) Except for adjusting the resin discharge rate from the extruder so that the thickness of the base layer (A) was 15.1 μm and the thickness of the surface layer (B) was 3.9 μm, the same conditions as in Example 1 were used to obtain a 20 μm biaxially oriented polypropylene film.

[0108] (Example 3) The surface layer (B) was made using a mixture of 45.0% by weight of polypropylene homopolymer PP-1 shown in Table 1, 52.0% by weight of ethylene copolymer polypropylene polymer PP-3 shown in Table 1, and 3.0% by weight of masterbatch A shown in Table 2. The conditions were the same as in Example 1, and a 20 μm biaxially oriented polypropylene film was obtained.

[0109] (Example 4) The surface layer (B) was made using a mixture of 1.2% by weight of polypropylene homopolymer PP-1 shown in Table 1, 94.0% by weight of ethylene copolymer polypropylene polymer PP-3 shown in Table 1, and 4.8% by weight of masterbatch A shown in Table 2. The conditions were the same as in Example 1, and a 20 μm biaxially oriented polypropylene film was obtained.

[0110] (Example 5) Except for changing the polypropylene homopolymer PP-1 used in the base layer (A) and surface layer (C) to PP-2 as shown in Table 1, and changing the film formation conditions to b as shown in Table 3, the same conditions as in Example 1 were used to obtain a 20 μm biaxially oriented polypropylene film.

[0111] (Comparative Example 1) A 20 μm biaxially oriented polypropylene film was obtained under the same conditions as in Example 1, except that the surface layer (B) was made by blending PP-1, a polypropylene homopolymer shown in Table 1, in an amount of 95.2% by weight and masterbatch A, shown in Table 2, in an amount of 4.8% by weight.

[0112] (Comparative Example 4) For the surface layer (B), a mixture of 47.25% by weight of the polypropylene homopolymer PP-1 shown in Table 1, 52.00% by weight of the ethylene copolymer polypropylene polymer PP-3 shown in Table 1, and 0.75% by weight of the masterbatch B shown in Table 2 was used. For the surface layer (C), a mixture of 98.4% by weight of the polypropylene homopolymer PP-1 shown in Table 1 and 1.60% by weight of the masterbatch B shown in Table 2 was used. The same conditions as in Example 1 were used, except that the film was formed so that the surface layer (C) was in contact with the cooling roll, to obtain a 20 μm biaxially oriented polypropylene film.

[0113] (Comparative Example 5) A 20 μm biaxially oriented polypropylene film was obtained under the same conditions as in Example 1, except that the base layer (A) used 99.0% by weight of the polypropylene homopolymer PP-1 shown in Table 1 and 1.0% by weight of stearyl diethanolamine stearate (Matsumoto Oil & Fat Co., Ltd. KYM-4K) as an antistatic agent.

[0114] (Comparative Example 6) Except for changing the film formation conditions to c in Table 3, the conditions were the same as in Example 1, and a 20 μm biaxially oriented polypropylene film was obtained.

[0115] Tables 4 and 5 show the raw materials, manufacturing methods, and physical properties of the films used in the above examples and comparative examples.

[0116] (Inorganic thin film layer) The methods for preparing the inorganic thin film layers used in each example and comparative example are described below. These methods were used in Examples 1-6 and Comparative Examples 1, 4-6, and are shown in Table 3. Note that no inorganic thin film layer was laminated in Comparative Example 2. (Formation of inorganic thin film layer M-1) As the inorganic thin film layer M-1, aluminum oxide was deposited onto the substrate film layer. The method for depositing aluminum oxide onto the substrate film layer involved setting the film on the unwinding side of a continuous vacuum deposition machine and winding the film through a cooling metal drum. At this time, the pressure of the continuous vacuum deposition machine was reduced to 10⁻⁴ Torr or less, and 99.99% pure metallic aluminum was loaded into an alumina crucible from the bottom of the cooling drum. The metallic aluminum was heated and evaporated, and oxygen was supplied into the vapor to cause an oxidation reaction, causing it to adhere and deposit onto the film, forming a 10 nm thick aluminum oxide film.

[0117] (Formation of inorganic thin film layer M-2) As the inorganic thin film layer M-2, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the substrate film layer by electron beam deposition. Particulate SiO2 (99.9% purity) and A12O3 (99.9% purity) of approximately 3mm to 5mm in size were used as the deposition source. The thickness of the inorganic thin film layer (SiO2 / A12O3 composite oxide layer) in the resulting film (inorganic thin film layer / coating layer-containing film) was 13nm. The composition of this composite oxide layer was SiO2 / A12O3 (mass ratio) = 60 / 40.

[0118] (Barrier coating layer E for Comparative Example 3) The details of the coating solution used for barrier coat layer E in Comparative Example 3 are described below.

[0119] [Polyvinyl alcohol resin (A)] 90 parts by mass of purified water were mixed with 10 parts by mass of fully saponified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: G Polymer OKS8049Q, (saponification degree 99.0% or higher, average degree of polymerization 450)). The mixture was heated to 80°C while stirring, and then stirred for approximately 1 hour. After that, it was cooled to room temperature to obtain a nearly transparent polyvinyl alcohol solution (PVA solution) with a solid content of 10%.

[0120] [Coating liquid used for barrier coat layer E] The following materials were mixed in the specified proportions to create a coating solution (resin composition for the barrier coat layer). Ion-exchanged water 35.00% by mass Isopropyl alcohol 15.00% by mass Polyvinyl alcohol resin (A) 50.00% by mass

[0121] [Coating of the film with a coating solution (lamination of barrier coat layer E)] The coating solution prepared above was applied to the corona-treated surface of the substrate film by gravure roll coating, pre-dried at 110°C, and then fully dried at 140°C to obtain a barrier coat layer E. The coating amount after drying was 0.25 g / m2 (Dry). Subsequently, a post-heat treatment was performed at 40°C for 2 days.

[0122] As described above, laminated films comprising an inorganic thin film layer or a barrier coating layer on a base film were prepared. Various evaluations were performed on the obtained laminated films. The results are shown in Table 5.

[0123] [Table 4]

[0124] [Table 5] [Industrial applicability]

[0125] According to the present invention, it is possible to provide a laminated film that can form a laminate structure composed of almost a single resin type, mainly polypropylene film, which has a low environmental impact, and that has the necessary gas barrier properties and adhesive properties required for packaging materials. Moreover, since the laminated film of the present invention has few processing steps and excellent processability and can be easily manufactured, it is excellent in both economy and production stability, and can provide a gas barrier film with homogeneous properties. [Explanation of symbols]

[0126] 1. Base plate, 2,8. Film holder, 2a. Groove hole, 2c. Hole, 2d. Small hole, 3. Screw, 4,5. Film, 6. Vacuum pump, 7. Pipe, X. Film overlap.

Claims

1. A laminated film comprising a base layer (A) mainly composed of a polypropylene resin, a surface layer (B) made of a polypropylene resin composition on one surface of the base layer (A), a surface layer (C) made of a polypropylene resin composition on the other surface of the base layer (A), and further comprising an inorganic oxide thin film layer (D) laminated on the surface layer (B), wherein the laminated film has a tensile modulus of elasticity of 2.6 GPa or less in the MD direction, a tensile modulus of elasticity of 4.1 GPa or more in the TD direction and a haze of 5% or less, and the inorganic oxide thin film layer (D) side surface of the laminated film satisfies the following requirements (I) to (V). (I) The arithmetic mean roughness (Ra) measured in a 2 μm square area using a scanning probe microscope is 4.5 nm or greater and 9.0 nm or less. (II) Martens hardness of 310 N / mm ２ below (III) Water contact angle is 10° or more and 75° or less (IV) The mean center surface roughness (SRa) measured by a 3D roughness analyzer is 0.010 μm or greater and 0.040 μm or less. (V) When the oxygen permeability value of the laminated film measured under 23°C × 65% RH conditions is (A) and the oxygen permeability value measured under 23°C × 80% RH conditions is (B), the rate of deterioration of the barrier value under high temperature and high humidity conditions, expressed by the following formula, is 130% or less. Barrier value deterioration rate (%) under high temperature and high humidity conditions = (B / A) × 100 Equation (1)

2. The oxygen permeability of the aforementioned laminated film under a 23°C × 65% RH environment is 60 cc / m². ２ • Water vapor transmission rate of 4 g / m³ at d·atm or less and under a 40°C × 90% RH environment. ２ The laminated film according to claim 1, characterized in that it is less than or equal to d.

3. The laminated film according to claim 1 or 2, characterized in that the mean center surface roughness (SRa) measured by a three-dimensional roughness meter on the surface of the surface layer (C) of the laminated film is 0.020 μm or more.

4. The Martens hardness of the surface on the surface layer (C) side of the laminated film is 270 N / mm². ２ The laminated film according to any one of claims 1 to 3, characterized in that it is as described above.

5. A laminated film according to any one of claims 1 to 4, wherein the thickness of the laminated film is 9 μm to 200 μm.

6. A packaging material comprising a laminated film according to any one of claims 1 to 5, with an olefin-based sealant layer laminated on one side.

Images