Laminated film and method for producing the same, and laminate and packaging material

Abstract

To provide a laminated film having excellent recyclability while ensuring sufficient heat-sealing and laminating properties and a method for producing the same, and a laminate and a packaging material.SOLUTION: A laminated film includes a base film and a heat seal layer laminated on the base film, wherein the base film is drawn, the heat seal layer remains undrawn, both the base film and the heat seal layer include an identical type of polyolefin resin, and the base film and the heat seal layer are in direct contact.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated film, a method for producing the same, a laminate, and a packaging material. [Background technology]

[0002] Generally, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and capable of mass production. For these reasons, plastic films are used in a wide variety of applications. Applications of plastic films are diverse, including, for example, packaging materials for food products and medicines, intravenous drip packs, shopping bags, posters, tapes, optical films for LCD televisions, protective films, window films for application to windows, greenhouses, building materials, and the like. For these applications, appropriate plastic materials are selected according to the application.

[0003] For example, in packaging materials, laminated films are widely used, in which a resin film with excellent strength and heat resistance, such as polyester film or nylon film, is used as a base film, and a resin film with excellent flexibility and low-temperature heat-sealability, such as polyethylene or polypropylene, is laminated on top of it as a sealant film (or heat-seal layer).By using multiple different plastics as the base film and sealant film, a packaging bag can be obtained in which, when heat-sealed with the sealant film side facing inward, the inside is sufficiently fused and the outside is free of deformation such as wrinkles.

[0004] On the other hand, in recent years, there has been a demand for the realization of a sustainable society, and there is a desire to recycle packaging materials as well. From this perspective, technologies are being developed to separate laminated films made of multiple materials into individual resin materials (see, for example, Patent Document 1 below). However, with such methods, impurities must be accurately removed to ensure successful recycling, which poses the problem of requiring a lot of time, energy, and cost. Technologies that take recyclability into consideration are also being studied; for example, Patent Document 2 below proposes a polyethylene laminate for packaging materials in which an oriented polyethylene film and a heat-sealable polyethylene layer are laminated with an adhesive layer containing a solventless adhesive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2021 / 132683 [Patent Document 2] Japanese Patent Application Publication No. 2019-189333 Summary of the Invention [Problem to be solved by the invention]

[0006] The laminate described in Patent Document 2 is made up of a combination of resin films of the same type, eliminating the need to separate each resin material during recycling. However, the laminate does not take into consideration the possibility that the adhesive layer, which is used to ensure sufficient lamination, may become a foreign substance if the laminate is recycled without separating the layers.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a laminated film that has sufficient heat-sealing properties and lamination properties while also being highly recyclable, a method for producing the same, and a laminate and packaging material. [Means for solving the problem]

[0008] The present invention relates to the following [1] to [7]. [1] A laminated film comprising a base film and a heat seal layer laminated on the base film, wherein the base film is stretched, the heat seal layer is not stretched, the base film and the heat seal layer contain the same type of polyolefin resin, and the base film and the heat seal layer are in direct contact with each other. [2] The laminated film according to [1], wherein the surface BS1 of the base film that contacts the heat seal layer and the surface HS1 of the heat seal layer that contacts the base film are not surface-treated. [3] The laminated film according to [1] or [2], wherein the base film comprises a first layer in contact with the heat seal layer and a second layer having a melting point higher than the melting point of the first layer. [4] The laminate film according to any one of [1] to [3], wherein the polyolefin resin is a polypropylene-based resin, and the planar orientation M calculated by the following method is 0.5 or more and 0.9 or less on the surface BS2 of the base film opposite the side that contacts the heat seal layer, and is −0.3 or more and 0.3 or less on the surface HS2 of the heat seal layer opposite the side that contacts the base film. Calculation method for plane orientation M: The plane orientation M is calculated from the equation M = (0.6887ε - 0.4395) / (0.4962ε + 0.2198) using ε, expressed as ε = (α + β) / (γ + δ), based on the following absorbance peak intensities α, β, γ, and δ measured using polarized ATR-FTIR. (1) The incident light was fixed to S-polarized light, and the sample angle was rotated by 15 degrees. In the measured spectrum, -1 The arrangement of the sample in which the absorbance peak intensity is the largest is defined as the slow axis arrangement, and the absorbance peak intensity in the slow axis arrangement is defined as α, (2) When the incident light is S-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as β. (3) The incident light is P-polarized, and the slow axis arrangement is 997 cm -1 The absorbance peak intensity is γ, (4) When the incident light is P-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as δ. [5] A laminate comprising a vapor-deposited adhesion layer containing a thermoplastic resin, a vapor-deposited layer, and a protective layer laminated in this order on the base film of the laminate film according to any one of [1] to [4], and the vapor-deposited layer and the vapor-deposited adhesion layer are in direct contact with each other. [6] A packaging material comprising the laminate film according to any one of [1] to [4] or the laminate according to [5]. [7] A method for producing a laminated film comprising a base film and a heat seal layer laminated so as to be in direct contact with the base film, the method comprising: step A of extruding a resin composition containing a polypropylene-based resin and stretching it to obtain a base film; and step B of extrusion laminating a resin composition containing a polypropylene-based resin on one side of the base film to form a heat seal layer, wherein in step A, stretching is performed so that the planar orientation M, calculated by the method below, is 0.5 or more and 0.9 or less on the surface of the base film, and in step B, extrusion lamination is performed so that the planar orientation M, calculated by the method below, is -0.3 or more and 0.3 or less on the surface of the heat seal layer opposite the side in contact with the base film. Calculation method for plane orientation M: The plane orientation M is calculated from the equation M = (0.6887ε - 0.4395) / (0.4962ε + 0.2198) using ε, expressed as ε = (α + β) / (γ + δ), based on the following absorbance peak intensities α, β, γ, and δ measured using polarized ATR-FTIR. (1) The incident light was fixed to S-polarized light, and the sample angle was rotated by 15 degrees. In the measured spectrum, -1 The arrangement of the sample in which the absorbance peak intensity is the largest is defined as the slow axis arrangement, and the absorbance peak intensity in the slow axis arrangement is defined as α, (2) When the incident light is S-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as β. (3) The incident light is P-polarized, and the slow axis arrangement is 997 cm -1 The absorbance peak intensity is γ, (4) When the incident light is P-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as δ. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminate film having sufficient heat-sealing and laminating properties and also excellent recyclability, a method for producing the same, a laminate, and a packaging material. Other problems, configurations, and effects will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a laminated film according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing another example of the laminated film of the present embodiment. [Figure 3] 1 is a cross-sectional view schematically illustrating an example of a laminate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each drawing is a schematic view, and the size and shape of each part are appropriately exaggerated for ease of understanding. Also, for ease of explanation, the same reference numerals are used to denote corresponding parts in each drawing.

[0012] [Laminated film] The laminated film of this embodiment comprises a base film and a heat seal layer laminated on the base film, the base film being stretched, the heat seal layer being unstretched, the base film and the heat seal layer comprising the same type of polyolefin resin, and the base film and the heat seal layer being in direct contact with each other.

[0013] The laminated film of the present embodiment has the above-mentioned structure, and can have sufficient heat-sealing and laminating properties while also having excellent recyclability. The inventors believe that the reason for this effect is that the structure in which the stretched substrate film and the unstretched heat-sealing layer are in direct contact with each other improves adhesion, and further, the substrate film and the heat-sealing layer contain the same type of polyolefin resin, which enables sufficient lamination strength to be obtained by heat fusion without using an adhesive or anchor coat, and also improves recyclability.

[0014] Furthermore, the laminated film of the present embodiment can achieve sufficient lamination strength without using an adhesive or anchor coat, thereby suppressing the following problem of the adhesive layer becoming a foreign substance when the layers are recycled without being separated. It has been found that adhesives are typically crosslinked three-dimensionally, and therefore are prone to becoming foreign substances when reused through recycling. It has also been found that even when the adhesive content in a film is low, it is difficult to finely disperse crosslinked adhesives, and they are prone to becoming foreign substances. Such foreign substances can lead to fisheyes and reduced physical properties.

[0015] Fig. 1 is a cross-sectional view schematically showing an example of the laminate film of this embodiment. In the laminate film 10 shown in Fig. 1, a base film 20 and a heat-seal layer 30 are laminated in direct contact without the use of an adhesive. The base film 20 and the heat-seal layer 30 contain the same type of polyolefin resin, and the base film 20 is stretched while the heat-seal layer 30 is not stretched.

[0016] From the viewpoint of further improving the lamination properties between the base film 20 and the heat seal layer 30, it is preferable that the surface BS1 of the base film 20 that contacts the heat seal layer 30 and the surface HS1 of the heat seal layer 30 that contacts the base film 20 have not been subjected to surface treatment such as corona treatment or ozone treatment. The above surface treatments may be a factor that inhibits heat fusion bonding between resins of the same type, and tend to significantly reduce the lamination strength, particularly in heat fusion bonding between polyolefin resins.

[0017] When the main surface of the laminated film 10 on the heat seal layer 30 side is the front surface and the main surface on the base film 20 side is the back surface, the front surface can be heat sealed suitably.

[0018] <Base film> The base film 20 may be uniaxially stretched or biaxially stretched. From the viewpoint of strength, a biaxially stretched base film may be used, and from the viewpoint of productivity, a sequentially biaxially stretched base film may be used.

[0019] The stretching ratio in the machine direction (MD) of the base film 20 may be 2 to 10 times, or may be 3 to 7 times. The stretching ratio in the cross direction (TD) may be 3 to 15 times, or may be 5 to 12 times. When the MD and TD of the base film 20 are within the above ranges, the strength and transparency of the base film are easily obtained. Furthermore, when the MD and TD of the base film 20 are within the above ranges, the heat resistance of the laminate film 10 is easily improved. Here, heat resistance refers to the property of preventing shrinkage or wrinkles from occurring on the back side of the laminate film when the front side (heat seal layer) of the laminate film is heat-sealed.

[0020] The material constituting the base film 20 is a polyolefin resin. Examples of polyolefin resins include polyethylene-based resins and polypropylene-based resins. The base film 20 may be made of different resins (e.g., polyethylene-based resin and polypropylene-based resin), but from the viewpoint of improving recyclability, it may also be made of a single resin (e.g., polyethylene-based resin or polypropylene-based resin).

[0021] Examples of polyethylene-based resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) obtained by copolymerizing α-olefin and ethylene, medium-density polyethylene (MDPE), high-density polyethylene (HDPE), etc. The base film 20 may contain a single polyethylene-based resin, or may contain multiple polyethylene-based resins with different melting points, MFRs, etc.

[0022] The melting point of the polyethylene resin may be 90 to 140°C, which is the melting point of a typical polyethylene, or may be 100 to 140°C.

[0023] The MFR (melt flow rate) of the polyethylene resin may be 0.01-50, 0.05-20, or 0.1-10.

[0024] Examples of polypropylene-based resins include homopolypropylene (PP), block polypropylene, random polypropylene, and propylene-α-olefin copolymers. The base film 20 may contain a single polypropylene-based resin or multiple polypropylene-based resins with different melting points, MFRs, etc.

[0025] The melting point of the polypropylene resin may be 110 to 165°C, which is the melting point of general polypropylene, or may be 130 to 165°C.

[0026] The MFR (melt flow rate) of the polypropylene resin may be 0.01-50, 0.05-20, or 0.1-10.

[0027] When the base film 20 contains a polypropylene-based resin, the planar orientation M calculated by the following method may be 0.5 to 0.9, 0.6 to 0.9, or 0.7 to 0.85, on the surface BS2 of the base film opposite the side that contacts the heat-seal layer. When the planar orientation M of the base film 20 is within the above range, the strength and transparency of the base film are easily obtained. Furthermore, when the planar orientation M of the base film 20 is within the above range, the heat resistance of the laminate film 10 is easily improved.

[0028] (Calculation method of plane orientation M) The planar orientation M is calculated from the equation M = (0.6887ε - 0.4395) / (0.4962ε + 0.2198), where ε is expressed as ε = (α + β) / (γ + δ), based on the following absorbance peak intensities α, β, γ, and δ measured at 23°C using polarized ATR-FTIR. (1) The incident light was fixed to S-polarized light, and the sample angle was rotated by 15 degrees. In the measured spectrum, -1 The arrangement of the sample in which the absorbance peak intensity is the largest is defined as the slow axis arrangement, and the absorbance peak intensity in the slow axis arrangement is defined as α, (2) When the incident light is S-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as β. (3) The incident light is P-polarized, and the slow axis arrangement is 997 cm -1 The absorbance peak intensity is γ, (4) When the incident light is P-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as δ.

[0029] Incidentally, a conventional method for evaluating orientation is the dichroic ratio method, in which polarized light is incident on a film, the light totally reflected by the film surface is detected to measure the absorption spectrum, and the orientation is evaluated from the ratio of absorbance in the slow axis direction in the film plane to that in the fast axis direction perpendicular to it. However, this conventional method only uses S-polarized light, and the obtained orientation is limited to the slow axis direction in the film plane and the fast axis direction perpendicular to it, so it does not include information about the thickness direction of the film.

[0030] On the other hand, the plane orientation M of the present invention can measure the direction of molecular vibration by irradiating a sample with S-polarized light, which vibrates perpendicular to the incident plane, and P-polarized light, which vibrates parallel to the incident plane.

[0031] Specifically, the film is positioned with its fast axis aligned with the light's propagation direction, and S-polarized light is irradiated onto the film to obtain orientation information related to the slow axis. Irradiating the film with P-polarized light provides orientation information related to the fast axis and the depth direction, i.e., the film's thickness. Next, the sample is rotated 90 degrees and S-polarized light is irradiated onto the film to obtain orientation information related to the fast axis. Irradiating the film with P-polarized light provides orientation information related to the slow axis and the thickness direction. From this orientation information, molecular orientation information can be determined for the slow axis, fast axis, and thickness directions. Furthermore, because it is possible to specifically analyze molecular orientation on the sample surface down to a depth of approximately 1 μm, the infrared light's penetration depth, it is possible to analyze molecular orientation on the sample surface regardless of sample thickness.

[0032] In polypropylene resins, the 997cm -1 The peak at 997 cm is attributed to the hybrid vibration of C-CH3 rocking, C-CH3 stretching, and CH bending, and is a band that absorbs parallel vibrations to the molecular chain, i.e., parallel polarized light. For this reason, in the spectrum measured by fixing the incident light to S-polarized light and rotating the sample angle by 15 degrees, -1It can be seen that the sample orientation where the absorbance peak intensity is greatest is the orientation in which the molecular chains are generally oriented in the film plane direction (hereinafter referred to as the slow axis orientation). The ratio of the absorbance peak intensity α at this time to the absorbance peak intensity β when the orientation is rotated 90 degrees from the slow axis orientation is the dichroic ratio, which indicates the degree of orientation in the plane direction.

[0033] If the polarization of the incident light is P-polarized, the information includes not only the component in the plane direction of the film but also the component in the thickness direction. Therefore, by comparing this with information from S-polarized light, which can measure only the component in the plane direction of the film, it is possible to evaluate the degree of orientation in the thickness direction.

[0034] As a result of various investigations, the range of the plane orientation M on the surface BS2 described above was determined to be the range of the absorbance peak intensity α and the absorbance peak intensity β described above, and the 997 cm -1 The absorbance peak intensity γ of 997 cm in the configuration rotated 90 degrees from the slow axis configuration -1 This is based on the finding that the planar orientation M calculated from the above formula using the absorbance peak intensity δ of the substrate film is correlated with the strength and transparency of the substrate film and the heat resistance of the laminate film.

[0035] The planar orientation M of the base film 20 can be controlled by changing the stretching temperature, stretching ratio, etc. in the stretching step. For example, the planar orientation M tends to increase as the stretching temperature in the stretching step decreases, and the planar orientation M tends to increase as the stretching ratio increases.

[0036] The base film 20 may have a laminated structure of two or more layers. For example, as shown in FIG. 2, the base film 20 may include a first layer 21 in contact with the heat-seal layer 30 and a second layer 22 having a melting point higher than that of the first layer 21. In this case, the temperature range for heat-sealing the base film 20 and the heat-seal layer 30 can be expanded, particularly at lower temperatures, thereby realizing a laminated film with a wide process window. Such a laminated film facilitates heat-sealing when bonding the base film 20 and the heat-seal layer 30 together by a technique such as extrusion lamination, and can improve laminate strength even when laminating at low temperatures.

[0037] The first layer 21 can function as a contact region that is in close contact with the heat-seal layer 30, and the second layer 22 can function as a non-contact region that is not in contact with the heat-seal layer 30. To facilitate bonding of the heat-seal layer 30, the melting point Tm1 of the resin that constitutes the first layer 21 is preferably lower than the melting point Tm2 of the resin that constitutes the second layer 22. From the viewpoint of achieving both lamination properties and heat resistance, the melting point Tm1 is preferably 5°C or more lower than the melting point Tm2. Here, "the melting point Tm1 being lower than the melting point Tm2" may mean that the peak temperature of the heat of fusion is low, or that the proportion of the low-melting-point component in the resin that constitutes the first layer 21 is higher than the proportion of the low-melting-point component in the resin that constitutes the second layer 22. Examples of low-melting-point components include polyethylene-based resins with a melting point of 90 to 130°C and polypropylene-based resins with a melting point of 110 to 155°C. Examples of the high melting point component include polyethylene resins with a melting point of 110 to 140°C and polypropylene resins with a melting point of 140 to 165°C.

[0038] Various additives may be blended into the substrate film 20. Examples of additives include antiblocking agents, crosslinking agents, nucleating agents, fillers, reinforcing agents, slip agents, lubricants, plasticizers, antioxidants, heat stabilizers, weathering agents, light stabilizers, UV absorbers, antistatic agents, flame retardants, flame retardant assistants, antifogging agents, pigments, dyes, dispersants, neutralizing agents, natural oils, synthetic oils, waxes, and modifying resins. These may be used alone or in combination of two or more.

[0039] The thickness of the base film 20 may be 8 μm or more and 80 μm or less, or 12 μm or more and 50 μm or less, from the viewpoint of improving the strength and transparency of the base film and the heat resistance of the laminated film.

[0040] <Heat seal layer> The heat seal layer 30 is unstretched, which allows for low-temperature heat sealing. By providing the laminate film 10 with such a heat seal layer 30, heat sealing at low temperatures becomes possible, and shrinkage and wrinkles can be less likely to occur. The laminate film 10 can also have excellent flexibility.

[0041] The material constituting the heat-seal layer 30 is the same type of polyolefin resin as the polyolefin resin contained in the base film 20. The heat-seal layer 30 may contain the above-mentioned polyethylene-based resin, or may contain a plurality of polyethylene-based resins with different melting points, MFR, etc., or may contain the above-mentioned polypropylene-based resin, or may contain a plurality of polypropylene-based resins with different melting points, MFR, etc. From the viewpoint of low-temperature heat-sealability and flexibility, the heat-seal layer 30 may contain a propylene-α-olefin copolymer as the polypropylene-based resin, or may contain linear low-density polyethylene (LLDPE) obtained by copolymerizing α-olefin and ethylene as the polyethylene-based resin.

[0042] When the heat-seal layer 30 contains a polypropylene-based resin, the planar orientation M calculated by the above method may be −0.3 or more and 0.3 or less, −0.2 or more and 0.2 or less, or −0.1 or more and 0.1 or less on the surface HS2 of the heat-seal layer opposite the side that contacts the base film. When the planar orientation M of the heat-seal layer 30 is in the above range, the low-temperature heat-sealability and flexibility of the heat-seal layer 30 can be improved.

[0043] The planar orientation M of the heat seal layer 30 can be controlled by changing the take-up speed, air gap, etc. in the extrusion lamination process for forming the heat seal layer 30. For example, the planar orientation M tends to increase as the take-up speed in the extrusion lamination process increases, and the planar orientation M tends to increase as the air gap decreases. Here, the air gap refers to the distance from the T-die to the lamination section.

[0044] The heat seal layer 30 may contain various additives. Examples of additives include antiblocking agents, crosslinking agents, nucleating agents, fillers, reinforcing agents, slip agents, lubricants, plasticizers, antioxidants, heat stabilizers, weathering agents, light stabilizers, UV absorbers, antistatic agents, flame retardants, flame retardant assistants, anti-fogging agents, pigments, dyes, dispersants, neutralizing agents, natural oils, synthetic oils, waxes, and modifying resins. These may be used alone or in combination of two or more.

[0045] From the viewpoint of improving the strength of the laminated film and the heat seal strength, the thickness of the heat seal layer 30 may be 20 μm or more and 150 μm or less, 30 μm or more and 120 μm or less, or 40 μm or more and 100 μm or less.

[0046] The laminated film 10 can also be laminated with other substrates or functional layers, thereby improving heat resistance and strength, and imparting other functions.

[0047] The laminated film can be produced, for example, by preparing a substrate film and laminating a heat-seal layer on one side of the substrate film. The substrate film can be formed, for example, by melting a resin composition containing a polyolefin resin, extruding the melt-extrusion molding method, such as a T-die molding method or an inflation molding method, and stretching (for example, biaxial stretching). The heat-seal layer can be formed by melting a resin composition containing a polyolefin resin, extruding it from a T-die, and pressing it against the substrate film that has been conveyed (a method similar to so-called extrusion lamination).

[0048] In the above-described method, the substrate film and heat-seal layer containing the same polyolefin resin can be bonded together by heat fusion, thereby reducing the air gap between the T-die and the position where the substrate film is pressed against the heat-seal layer (lamination portion) and enabling lamination at a relatively low temperature. This allows sufficient laminate strength to be obtained without surface treatments such as ozone treatment to oxidize the surface of the heat-seal layer or surface treatments such as anchor coating or corona treatment for the substrate film. The laminate film of this embodiment simplifies the manufacturing process and is highly recyclable because the inclusion of impurity materials is sufficiently suppressed. Furthermore, the laminate film of this embodiment can be manufactured without excessively high temperature treatment, which can suppress resin degradation.

[0049] In the above method, if necessary, the temperature of the cooling roll that presses the heat seal layer against the base film can be increased to increase the time for heat fusion.

[0050] When the base film has a multilayer structure, for example, it can be produced by coextrusion followed by stretching (for example, biaxial stretching) to produce a multilayer base film. When the heat seal layer has a multilayer structure, for example, it can be formed by using a die via a feed block or a multi-manifold.

[0051] When the base film and the heat seal layer contain a polypropylene-based resin as the same type of polyolefin resin, the laminated film may be produced by the following method.

[0052] <Laminated film manufacturing method> The method for producing a laminated film of the present embodiment is a method for producing a laminated film comprising a base film and a heat seal layer laminated so as to be in direct contact with the base film, and comprises: step A of extruding a resin composition containing a polypropylene-based resin and stretching it to obtain a base film; and step B of extrusion laminating a resin composition containing a polypropylene-based resin onto one side of the base film to form a heat seal layer.

[0053] In step A, from the viewpoint of improving the strength and transparency of the substrate film and the heat resistance of the laminate film, stretching may be performed so that the planar orientation M calculated by the above method is 0.5 to 0.9, 0.6 to 0.9, or 0.7 to 0.85 on the surface of the substrate film. The planar orientation M can be adjusted by the above method.

[0054] The stretching in step A may be uniaxial stretching or biaxial stretching.

[0055] In step B, from the viewpoint of improving the low-temperature heat sealability and flexibility of the heat seal layer, extrusion lamination may be performed so that the planar orientation M calculated by the above method is −0.3 or more and 0.3 or less, −0.2 or more and 0.2 or less, or −0.1 or more and 0.1 or less on the surface of the heat seal layer opposite the side that contacts the base film. The planar orientation M can be adjusted by the above method.

[0056] <Laminate> The laminate of this embodiment has a vapor-deposited adhesion layer containing a thermoplastic resin, a vapor-deposited layer, and a protective layer laminated in this order on the base film of the laminate film of this embodiment described above, with the vapor-deposited layer and the vapor-deposited adhesion layer being in direct contact with each other.

[0057] FIG. 3 is a cross-sectional view schematically illustrating an example of a laminate according to this embodiment. The laminate 100 shown in FIG. 3 includes a substrate film 20 having a laminated structure of a heat seal layer 30, a first layer 21, and a second layer 22, a vapor-deposited adhesion layer 33, a vapor-deposited layer 40, and a protective layer 50, laminated in this order. The laminate 100 has the above-described structure, which improves gas barrier properties. The vapor-deposited adhesion layer 33 contains a thermoplastic resin, which can be finely dispersed through a kneading process during recycling of the laminate, making it less likely to become a foreign substance. This improves adhesion to the vapor-deposited layer without significantly impairing the recyclability of the laminate.

[0058] The laminate 100 includes a base film 20 having a two-layer structure, which allows the heat seal layer 30 and the first layer 21 to be well adhered to each other by heat fusion, thereby providing sufficient adhesion strength.

[0059] The vapor-deposited adhesion layer 33 functions as a region (vapor-deposited adhesion region) that improves adhesion to the vapor-deposited layer 40. The material constituting the vapor-deposited adhesion layer 33 is a thermoplastic resin, and the above-mentioned polyolefin resin or a resin having a polar group can be used. Examples of resins having a polar group include polyamide resin, polyester resin, ethylene-vinyl alcohol copolymer (EVOH), and polyvinyl alcohol (PVA).

[0060] When the vapor-deposited adhesive layer 33 contains a resin having a polar group, an adhesive resin may be used between the vapor-deposited adhesive layer 33 and the second layer 22. In this case, from the viewpoint of recyclability, the mass proportion of the vapor-deposited adhesive layer 33 in the laminate 100 may be 20 mass % or less, 10 mass % or less, or 5 mass % or less, based on the total mass of the laminate.

[0061] From the viewpoint of recyclability of the laminate, the vapor-deposited adhesive layer 33 may contain the same type of polyolefin resin as the polyolefin resin contained in the base film.

[0062] Filler particles may be added to the vapor-deposited adhesion layer 33. In this case, it is preferable that the surface of the vapor-deposited adhesion layer 33 that comes into contact with the vapor-deposited layer 40 is smooth before the vapor-deposited layer 40 is formed. Furthermore, the surface of the vapor-deposited adhesion layer 33 that comes into contact with the vapor-deposited layer 40 may be subjected to a surface treatment such as plasma treatment as a pretreatment before the vapor-deposited layer 40 is formed.

[0063] From the viewpoint of recyclability, the thickness of the vapor-deposited adhesive layer 33 may be 0.2 μm or more and 5.0 μm or less, or 0.5 μm or more and 3.0 μm or less.

[0064] The deposition layer 40 can be formed by a conventionally known method, for example, a physical vapor deposition method (PVD method) such as vacuum deposition, sputtering, or ion plating, or a chemical vapor deposition method (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, or photochemical vapor deposition.

[0065] Materials constituting the vapor-deposited layer 40 include metals such as aluminum, and inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide. Aluminum oxide or silicon oxide is particularly preferred because of its excellent productivity and excellent oxygen and water vapor barrier properties in heat resistance and moist heat resistance. The vapor-deposited layer may be formed of one type of material, or two or more appropriately selected materials.

[0066] The thickness of the vapor-deposited layer 40 may be from 0.001 μm to 0.2 μm, or from 0.005 μm to 0.1 μm. By setting the thickness of the vapor-deposited layer 40 within the above range, it is possible to impart sufficient gas barrier properties while sufficiently minimizing the impact on recyclability, and cracks and the like are less likely to occur in the vapor-deposited layer.

[0067] The protective layer 50 may contain, as constituent materials, at least one of a metal alkoxide, its hydrolysate, and its reaction product, and a coating agent, and may further contain at least one of a silane coupling agent and its hydrolysate.

[0068] Examples of metal alkoxides and their hydrolysates include compounds represented by the general formula M(OR), such as tetraethoxysilane [Si(OC2H5)4] and triisopropoxyaluminum [Al(OC3H7)3]. n and hydrolysates thereof. Only one of these may be contained, or two or more of them may be contained in appropriate combination.

[0069] A water-soluble polymer can be used as the coating agent. Examples of water-soluble polymers include polyvinyl alcohols, polysaccharides such as starch, methyl cellulose, and carboxymethyl cellulose, and various polymers such as acrylic polyols. To further improve the oxygen gas barrier properties, the protective layer may contain a polyvinyl alcohol polymer.

[0070] The protective layer 50 can be formed by a conventionally known method, for example, a wet coating method such as a casting method, a dipping method, a roll coating method, a gravure coating method, a screen printing method, a reverse coating method, a spray coating method, a kit coating method, a die coating method, a metaling bar coating method, a chamber doctor combined coating method, or a curtain coating method.

[0071] The thickness of the protective layer 50 may be from 0.05 μm to 1 μm, or from 0.1 μm to 0.5 μm. By setting the thickness of the protective layer 50 within the above range, it is possible to impart sufficient oxygen barrier properties while sufficiently minimizing the impact on recyclability, making it easy to form a uniform coated surface, and reducing the drying load and manufacturing costs.

[0072] The laminate of this embodiment can be produced by producing the laminate film of this embodiment by the method described above, and then providing a vapor-deposited adhesive layer, a vapor-deposited layer, and a protective layer in this order on the substrate film side of the laminate film by the method described above. When the laminate includes a substrate film having a first layer and a second layer, the first layer, the second layer, and the vapor-deposited adhesive layer may be multilayered using, for example, a feed block or a die via a multi-manifold.

[0073] <Packaging material> The packaging material of this embodiment includes the laminate film of this embodiment or the laminate of this embodiment.

[0074] For example, a packaging bag can be produced by folding a packaging material including the laminate film 10 in half, overlapping the laminate film 10 so that the heat seal layer 30 of the laminate film 10 is on the inside, and heat sealing the edges. Alternatively, a packaging bag can be produced by overlapping two laminate films 10 so that the heat seal layers 30 face each other, and heat sealing the edges.

[0075] A packaging bag can be produced by folding the packaging material including the laminate 100 in half, overlapping the laminate 100 so that the heat seal layer 30 is on the inside, and heat sealing the edges. Alternatively, a packaging bag can be produced by overlapping two sheets of the laminate 100 so that the heat seal layers 30 face each other, and heat sealing the edges.

[0076] Examples of heat sealing types include side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, palm seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, gusset type, etc. By appropriately selecting these, packaging bags of various types can be produced.

[0077] The packaging material of this embodiment can be used to produce, for example, a self-standing packaging bag (standing pouch). The manufacturing method for the self-standing packaging bag is not particularly limited. Heat sealing can be performed by any known method, such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, or ultrasonic sealing.

[0078] The packaging material of this embodiment has sufficient heat-sealing and laminating properties, and also has excellent recyclability, so that packaging bags with excellent recyclability can be produced. [Example]

[0079] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0080] Example 1 A 1 mm thick unstretched sheet was extruded using Prime Polymer's F-300SP polypropylene resin (melting point 161°C). This sheet was then biaxially stretched at 5x MD and 10x TD magnifications to produce a 20 μm thick film (biaxially stretched PP-1). This film was used as the base film, and a 60 μm thick heat seal layer (extrusion laminated PP-1) was extrusion laminated to produce a laminated film. Prime Polymer's F-744NP polypropylene resin (melting point 133°C) was used for the extrusion lamination. During extrusion lamination, no surface treatments, such as corona treatment of the base film or ozone treatment of the heat seal layer, were performed. The discharge temperature and take-up speed were adjusted so that the resin temperature at the laminated section was 250°C.

[0081] Example 2 A uniaxially oriented polyethylene film PE3K-H (25 μm thick) (uniaxially oriented PE-2) manufactured by Futamura Chemical Co., Ltd. was used as the base film, and a 60 μm thick heat seal layer (extrusion laminate PE-2) was attached by extrusion lamination to obtain a laminated film. The polyethylene resin SP2040 manufactured by Prime Polymer Co., Ltd. was used as the resin for extrusion lamination. During extrusion lamination, no surface treatment such as ozone treatment was performed on the heat seal layer, and the discharge temperature and take-up speed were adjusted so that the resin temperature in the laminated area was 180°C.

[0082] (Comparative Example 1) A single-layer unstretched film (CPP-C1) with a thickness of 80 μm was prepared by extrusion molding using polypropylene resin F-744NP manufactured by Prime Polymer Co., Ltd.

[0083] (Comparative Example 2) A 1 mm thick unstretched sheet was produced by extrusion molding using polypropylene resin F-300SP manufactured by Prime Polymer Co., Ltd., and then biaxially stretched at MD 5x and TD 10x to produce a 20 μm thick single-layer stretched film (biaxially stretched PP-C2).

[0084] (Comparative Example 3) A 1 mm thick unstretched sheet was produced by extrusion molding using polypropylene resin F-300SP manufactured by Prime Polymer Co., Ltd., and then biaxially stretched at MD 5x and TD 10x to produce a 20 μm thick film (biaxially stretched PP-C3). This film served as the base film. Additionally, a 60 μm thick unstretched film (CPP-C3) was produced by extrusion molding using polypropylene resin F-744NP manufactured by Prime Polymer Co., Ltd., and served as the heat seal layer. The base film and heat seal layer were bonded together by dry lamination using Mitsui Chemicals A-525 / A-52 (Adhesive 1) as an adhesive to obtain a laminated film. During dry lamination, both the base film and the heat seal layer were subjected to corona treatment.

[0085] Comparative Example 4 The substrate film was a uniaxially oriented polyethylene film PE3K-H (25 μm thick) (uniaxially oriented PP-C4) manufactured by Futamura Chemical Co., Ltd., and a 60 μm thick unstretched film (PE-C4) was extruded using polyethylene resin SP2040 manufactured by Prime Polymer Co., Ltd. The heat-seal layer was formed using a dry lamination technique. The substrate film and heat-seal layer were bonded together using an adhesive called LX-500 / KW-75 (Adhesive 2) manufactured by DIC Graphics Corporation to obtain a laminated film. During dry lamination, both the substrate film and the heat-seal layer were corona-treated.

[0086] (Comparative Example 5) A laminated film was obtained in the same manner as in Example 2, except that a polyethylene terephthalate film E5100 (thickness 12 μm) (biaxially stretched PET-C5) manufactured by Toyobo Co., Ltd. was used as the substrate film.

[0087] (Comparative Example 6) A laminated film was obtained in the same manner as in Comparative Example 4, except that a polyethylene terephthalate film E5100 (thickness 12 μm) (biaxially stretched PET-C6) manufactured by Toyobo Co., Ltd. was used as the substrate film.

[0088] [Evaluation of plane orientation M] The following absorbance peak intensities α, β, γ, and δ were measured at 23°C using polarized ATR-FTIR. Using ε, which is expressed as ε = (α + β) / (γ + δ), the planar orientation M was calculated from the formula M = (0.6887ε - 0.4395) / (0.4962ε + 0.2198). (1) The incident light was fixed to S-polarized light, and the sample angle was rotated by 15 degrees. In the measured spectrum, -1 The arrangement of the sample in which the absorbance peak intensity is the largest is defined as the slow axis arrangement, and the absorbance peak intensity in the slow axis arrangement is defined as α, (2) When the incident light is S-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as β. (3) The incident light is P-polarized, and the slow axis arrangement is 997 cm -1 The absorbance peak intensity is γ, (4) When the incident light is P-polarized and rotated 90 degrees from the slow axis arrangement, the 997 cm -1 The absorbance peak intensity is defined as δ.

[0089] In laminate films having a heat seal layer and a base film, the planar orientation M was measured for the surface HS2 (first surface) of the heat seal layer opposite the side that contacts the base film, and the surface BS2 (second surface) of the base film opposite the side that contacts the heat seal layer. In laminate films having an adhesive layer between the heat seal layer and the base film, the surface of the heat seal layer opposite the base film was designated the first surface, and the surface of the base film opposite the heat seal layer was designated the second surface, and the planar orientation M was measured for these surfaces. When the film was a monolayer film, the planar orientation M was measured for both main surfaces of the monolayer film.

[0090] The polarized ATR prism was ZnSe, and measurements were carried out using a single-reflection ATR with a 45-degree incidence angle. Materials other than polypropylene were excluded from this evaluation and were marked with a "-".

[0091] Regarding the surface orientation M of the base film, there was no difference between the value of the surface orientation M when only the base film was measured as a sample and the value of the surface orientation M on the opposite side of the base film from the side in contact with the heat seal layer after the heat seal layer was bonded.

[0092] [Evaluation of heat sealability] Using a Tester Sangyo heat sealer (model number TP-701-B), heat sealing was performed by stacking two laminated films with the heat seal layer on the inside (two films were stacked in Comparative Examples 1 and 2) at a sealing pressure of 0.2 MPa, a sealing time of 1 second, and a seal width of 10 mm. The heat sealing temperature was increased by +5°C in increments from -10°C, the melting point of the resin in the heat seal layer. When a heat sealing temperature condition was found that sealed the heat seal layer without the base film melting and sticking to the seal bar, it was marked with an "O"; when it was not found, it was marked with an "X."

[0093] [Evaluation of lamination] The laminated film was cut into a 15 mm wide x 100 mm piece, and a cutter was placed on the edge of the film to peel the interface between the heat seal layer and the base film. A T-peel test was then performed using a Shimadzu Corporation tensile tester (model number AGS-500NX). The pulling speed was 100 mm / min. Cases where the interface between the heat seal layer and the base film could not be peeled at all and where the average measured strength was 2 N / 15 mm or greater were marked with an "O"; cases where the average measured strength was less than 2 N / 15 mm were marked with an "X"; and cases where the single layer could not be peeled at all were marked with a "-".

[0094] [Recyclability evaluation] The laminated film was compressed, cut, and formed into granules to obtain a recycled material. This recycled material was extruded to produce an unstretched film with a thickness of 60 μm, and the appearance was visually inspected. Films with no significant fisheyes were marked with an "O" and those with significant fisheyes were marked with an "X."

[0095] (Overall judgment) If all of the above heat sealability evaluation, lamination evaluation, and recyclability evaluation were "good," the overall evaluation was rated "good," and if even one was "bad," the overall evaluation was rated "bad."

[0096] The film configurations and evaluation results in Examples 1 and 2 and Comparative Examples 1 to 6 are shown in Table 1. The abbreviations in Table 1 are as described above.

[0097] [Table 1]

[0098] Example 3 A 1 mm thick multilayer unstretched sheet was produced by coextrusion molding using polypropylene resins F-300SP (melting point 161 ° C) (PP-1) and F-744NP (melting point 133 ° C) (PP-2) manufactured by Prime Polymer Co., Ltd., and subsequently stretched at MD 5 times and TD 10 times to produce a 20 μm thick film, which served as the base film. The F-300SP resin layer served as the second layer (non-contact region), and the F-744NP resin layer served as the first layer (contact region), with a layer ratio of 18:2. A 60 μm thick heat seal layer (extrusion laminated PP-1) was bonded to the first layer side of this base film by extrusion lamination to obtain a laminated film. The resin used for extrusion lamination was polypropylene resin F-744NP manufactured by Prime Polymer Co., Ltd. During extrusion lamination, no surface treatments such as corona treatment on the base film or ozone treatment on the heat seal layer were performed, and the discharge temperature and take-up speed were adjusted so that the resin temperature in the laminated area would be 250°C.

[0099] Example 4 A laminated film was obtained in the same manner as in Example 3, except that the base film was subjected to a corona treatment and the heat seal layer was subjected to an ozone treatment during extrusion lamination.

[0100] [Evaluation of plane orientation M] The planar orientation M was evaluated in the same manner as above.

[0101] [Evaluation of temperature range for lamination] In the preparation of the laminated films of Examples 1, 3, and 4, the resin temperature of the laminated portion was lowered from 250°C by 10°C increments to prepare the laminated films, which were then cut into 15mm wide x 100mm pieces. A cutter was applied from the edge of the film to attempt peeling at the interface between the heat seal layer and the substrate film. In all examples, peeling was not possible when the resin temperature of the laminated portion was 250°C, but peeling became possible by lowering the resin temperature of the laminated portion. The temperature range at which lamination is possible is from the lowest temperature at which peeling is not possible to 250°C, and the wider this temperature range, the wider the process window and the better. Temperatures above 40°C were evaluated as "○," and temperatures below 40°C were evaluated as "△."

[0102] [Evaluation of heat sealability] The heat sealability was evaluated in the same manner as above.

[0103] [Evaluation of lamination] The lamination properties were evaluated in the same manner as above.

[0104] [Recyclability evaluation] The recyclability was evaluated in the same manner as above.

[0105] (Overall judgment) If the above heat sealability, lamination ability, and recyclability evaluations were all "good" and the laminating temperature range was also "good", the overall judgment was "good / bad", if the heat sealability, lamination ability, and recyclability evaluations were all "good" but the laminating temperature range was "good", the overall judgment was "good / bad", and if any one of the heat sealability, lamination ability, and recyclability evaluations was "bad", the overall judgment was "bad".

[0106] The film configurations and evaluation results for Examples 1, 3, and 4 are shown in Table 2. The base film in each of the films of Examples 1, 3, and 4 was a biaxially oriented polypropylene film, and the column for base film in the film configuration in Table 2 refers to the resin components that make up the base film. The abbreviations in Table 2 are as described above.

[0107] [Table 2]

[0108] Examples 5 to 10 Using Example 3 as the standard conditions, laminate films with different planar orientation M were produced by adjusting the stretching ratio and stretching temperature in the stretching process and the take-up speed and air gap in the extrusion lamination process.

[0109] In Example 5, based on Example 3, the M orientation was adjusted by lowering the draw ratio and increasing the draw temperature in the drawing step.

[0110] In Example 6, based on Example 3, the stretching temperature in the stretching step was increased to adjust the M orientation.

[0111] In Example 7, with Example 3 as the reference, the stretching temperature in the stretching step was lowered to adjust the M orientation.

[0112] In Example 8, based on Example 3, the M orientation was adjusted by slowing down the take-up speed in the extrusion lamination process.

[0113] In Example 9, based on Example 3, the M orientation was adjusted by increasing the take-up speed in the extrusion lamination process.

[0114] In Example 10, based on Example 3, the take-up speed in the extrusion lamination process was increased and the air gap was reduced to adjust the M orientation.

[0115] [Evaluation of plane orientation M] The planar orientation M was evaluated in the same manner as above.

[0116] [Evaluation of heat sealability] Heat sealing was carried out in the same manner as above. At this time, if a heat sealing temperature condition was found under which the heat seal layer was sealed and the base film was not melted and stuck to the seal bar, it was marked as "◯", if it was found but noticeable wrinkles occurred after sealing, it was marked as "△", and if it was not found, it was marked as "X".

[0117] [Evaluation of lamination] The lamination properties were evaluated in the same manner as above.

[0118] [Recyclability evaluation] The recyclability was evaluated in the same manner as above.

[0119] (Overall judgment) A sample that was evaluated as "good" in all of the above heat sealability, lamination, and recyclability evaluations was given an overall rating of "good." A sample that was evaluated as "good" in heat sealability and "good" in lamination and recyclability evaluations was given an overall rating of "good." All other samples were evaluated as "bad."

[0120] Table 3 shows the film configurations and evaluation results for Examples 3 and 5 to 10.

[0121] [Table 3]

[0122] (Evaluation results) As shown in Table 1, in Examples 1 and 2, in which the stretched substrate film and the unstretched heat seal layer were made of the same type of polyolefin resin and were in direct contact without the use of an adhesive, the heat sealability, lamination property, and recyclability were all evaluated as "Good," and the overall evaluation was also confirmed to be "Good."

[0123] Looking at the results for Examples 1 and 3 in Table 2, Example 3, which used F-744NP for the first layer, received a "Good" rating for the laminating temperature range, while Example 1, which did not use F-744NP for the first layer, received a "Poor" rating for the laminating temperature range. These results indicate that a lower melting point (Tm1) for the first layer relative to the melting point (Tm2) for the second layer allows for lamination at lower temperatures, making it preferable. However, it also indicates that lamination is possible even if the base film is not divided into a first and second layer by setting the appropriate resin temperature for the laminating section. Furthermore, when the melting point (Tm1) of the first layer is lower than the melting point (Tm2) of the second layer, extrusion lamination at lower temperatures is possible, which is expected to suppress resin degradation. Both Examples 1 and 3 received "Good" ratings for heat sealability, lamination, and recyclability, and the overall evaluation was consistent with the evaluation results for the laminating temperature range.

[0124] Looking at the results for Examples 3 and 4 in Table 2, Example 3, in which the interface between the base film and the heat-seal layer was not corona-treated or ozone-treated, had a laminating temperature range of "○," while Example 4, in which corona and ozone treatment was performed, had a laminating temperature range of "△." These results demonstrate that the interface between the base film and the heat-seal layer is preferably not corona-treated or ozone-treated, since lamination is possible at low temperatures. However, it also demonstrates that lamination is possible even with corona or ozone treatment by setting an appropriate resin temperature for the laminating section. Furthermore, when corona or ozone treatment is not performed, the laminating temperature range is broad, enabling extrusion lamination at low temperatures, which is expected to suppress resin degradation. Both Examples 1 and 4 received "○" marks for heat-sealability, lamination, and recyclability, and the overall evaluation was consistent with the evaluation results for the laminating temperature range.

[0125] From the results in Table 3, when the planar orientation M of the surface HS2 (first surface) of the heat seal layer not in contact with the base film was -0.3 or more and 0.3 or less, and the planar orientation M of the surface BS2 (second surface) of the base film not in contact with the heat seal layer was 0.5 or more and 0.9 or less, the heat sealability was rated "○". On the other hand, in Example 5, where the planar orientation M of the second surface was less than 0.5, and in Example 10, where the planar orientation M of the first surface exceeded 0.3, the heat sealability was rated "△". From these results, it can be seen that although it is preferable for the planar orientation M of the first surface to be -0.3 or more and 0.3 or less, and the planar orientation M of the second surface to be 0.5 or more and 0.9 or less, the heat seal temperature conditions can be found even if they are outside of these ranges. Both lamination and recyclability were rated "○", and the overall evaluation was consistent with the heat sealability evaluation results. [Explanation of symbols]

[0126] 10...Laminated film, 20...Base film, 21...First layer (contact area), 22...Second layer (non-contact area), 30...Heat seal layer, 33...Vapor-deposited adhesive layer, 40...Vapor-deposited layer, 50...Protective layer, 100...Laminate.

Claims

1. A substrate film and a heat seal layer laminated on the substrate film, the substrate film is stretched, The heat seal layer is not stretched, the base film and the heat seal layer contain the same type of polyolefin resin, A laminated film in which the base film and the heat seal layer are in direct contact with each other.

2. The surface BS of the base film that comes into contact with the heat seal layer １ and a surface HS of the heat seal layer that contacts the base film. １ The laminated film according to claim 1, which has not been subjected to a surface treatment.

3. The laminated film according to claim 1 , wherein the base film comprises a first layer in contact with the heat seal layer and a second layer having a melting point higher than that of the first layer.

4. the polyolefin resin is a polypropylene-based resin, The plane orientation M calculated by the following method is the surface BS of the substrate film opposite to the side in contact with the heat seal layer. ２ and the surface HS of the heat seal layer opposite to the side in contact with the base film is 0.5 or more and 0.9 or less. ２ The laminated film according to claim 1, wherein the σ is -0.3 or more and 0.3 or less. Calculation method of plane orientation M: The plane orientation M is calculated from the equation M=(0.6887ε−0.4395) / (0.4962ε+0.2198) using ε expressed as ε=(α+β) / (γ+δ) based on the following absorbance peak intensities α, β, γ, and δ measured using polarized ATR-FTIR. (1) The incident light was fixed to S-polarized light, and the sample angle was rotated by 15 degrees. In the measured spectrum, －１ The arrangement of the sample in which the absorbance peak intensity is the largest is defined as the slow axis arrangement, and the absorbance peak intensity in the slow axis arrangement is defined as α, (2) 997 cm when the incident light is S-polarized and rotated 90 degrees from the slow axis arrangement －１ The absorbance peak intensity is defined as β. (3) When the incident light is P-polarized and the slow axis is arranged as described above, the wavelength is 997 cm －１ The absorbance peak intensity is γ, (4) 997 cm when the incident light is P-polarized and rotated 90 degrees from the slow axis arrangement －１ The absorbance peak intensity is defined as δ.

5. The laminated film according to claim 1, wherein a vapor-deposited adhesive layer containing a thermoplastic resin, a vapor-deposited layer, and a protective layer are laminated in this order on the substrate film; The vapor-deposited layer and the vapor-deposited adhesive layer are in direct contact with each other.

6. A packaging material comprising the laminate film according to claim 1 or the laminate according to claim 5.

7. A method for producing a laminated film comprising a base film and a heat seal layer laminated so as to be in direct contact with the base film, A step A of extruding a resin composition containing a polypropylene-based resin and stretching the extrudate to obtain a substrate film; a step B of forming a heat seal layer on one surface of the base film by extrusion laminating a resin composition containing a polypropylene-based resin; Equipped with In the step A, the substrate film is stretched so that the planar orientation M calculated by the following method is 0.5 or more and 0.9 or less on the surface of the substrate film, In the step B, extrusion lamination is performed so that a planar orientation M calculated by the following method is −0.3 or more and 0.3 or less on the surface of the heat seal layer opposite to the side in contact with the base film. Calculation method of plane orientation M: The plane orientation M is calculated from the equation M=(0.6887ε−0.4395) / (0.4962ε+0.2198) using ε expressed as ε=(α+β) / (γ+δ) based on the following absorbance peak intensities α, β, γ, and δ measured using polarized ATR-FTIR. (1) The incident light was fixed to S-polarized light, and the sample angle was rotated by 15 degrees. In the measured spectrum, －１ The arrangement of the sample in which the absorbance peak intensity is the largest is defined as the slow axis arrangement, and the absorbance peak intensity in the slow axis arrangement is defined as α, (2) 997 cm when the incident light is S-polarized and rotated 90 degrees from the slow axis arrangement －１ The absorbance peak intensity is defined as β. (3) When the incident light is P-polarized and the slow axis is arranged as described above, the wavelength is 997 cm －１ The absorbance peak intensity is γ, (4) 997 cm when the incident light is P-polarized and rotated 90 degrees from the slow axis arrangement －１ The absorbance peak intensity is defined as δ.

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