Sealant films, packaging materials and packaging bags

Abstract

To provide a sealant film which enables recycling of a recycled material containing two or more kinds of resins while sufficiently having heat sealability and mechanical characteristics, a packaging material and a packaging bag.SOLUTION: A sealant film 1a includes a recycled material-containing layer 2 containing a recycled material containing two or more kinds of resins, and a sealant layer 3 laminated on one main surface of the recycled material-containing layer, wherein the recycled material-containing layer 2 includes a domain having permeation brightness smaller than that of its periphery, when the sealant film is permeated and observed from plane view of the sealant film, and the domain has a maximum area of 1,000 μm2 or less and a maximum aspect ratio of 10 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sealant film, a packaging material, and a packaging bag. [Background technology]

[0002] Generally, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and allowing for mass production, and are used in a variety of applications. Applications are diverse, including, for example, packaging materials for packaging food and medicines, infusion packs, shopping bags, posters, tapes, optical films for LCD televisions, protective films, window films for attaching to windows, vinyl greenhouses, building materials, and the like. Specific materials include, for example, thermoplastic resins such as polyethylene, polypropylene, polystyrene, polymethylmethacrylate, polycarbonate, polyamide, polyethylene terephthalate, and polybutylene terephthalate, and thermosetting resins such as epoxy resin, polyurethane, and polyimide.

[0003] Appropriate plastic materials are selected depending on the application, and multiple types of plastic materials are layered to form a laminate. In addition, multiple plastic materials can be mixed in one layer to make up for the shortcomings of a single material. There are also laminates that contain aluminum foil to provide light blocking properties, a printed layer with an ink pattern to give the product a design, and an adhesive layer to bond incompatible plastic materials together.

[0004] Recycling of plastic products is expected as a measure to address recent environmental problems, and various recycling methods are being considered. For example, technology has been established for material recycling of collected PET bottles, in which the products are washed and crushed and reused as raw materials, and chemical recycling, in which the products are converted into monomers. In addition, the following Patent Document 1 discloses technology related to a sealant film containing recycled polyethylene resin, and describes that recycled polyethylene is recovered from used polyethylene molded bodies or waste materials from the production thereof, and that the recycled polyethylene obtained through various processes such as crushing, washing, filtration, and extraction can be used.

[0005] In contrast, plastic films are composed of various materials, so it is difficult to reuse them as raw materials by simply washing and crushing them.Specifically, because an unspecified number of resins are mixed, it is difficult to obtain uniform melt properties (fluidity) and to mold them, and even if they could be molded, the mechanical strength would be insufficient.

[0006] Due to these restrictions, most plastic films are sent for thermal recycling, but due to the large amount of plastic film in circulation, there is a strong demand for plastic films to be recycled as raw materials for film products such as packaging materials.

[0007] Methods for recycling plastic films have been studied in the past. For example, Patent Document 2 listed below proposes a method for efficiently extracting EVOH (ethylene-vinyl alcohol copolymer) from a multilayer resin molding that includes an EVOH layer that functions as a gas barrier film. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2022 / 124229 [Patent Document 2] International Publication No. 2022 / 158287 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the above method involves dissolving EVOH in an EVOH extractant and then recovering EVOH by precipitation / sedimentation, which increases the time and cost required and makes it difficult to use.

[0010] Patent Document 1 proposes a sealant film in which an intermediate layer containing recycled polyethylene is placed between two virgin polyethylene layers made from virgin materials that have never been processed, and the film is evaluated for its deodorizing and concealing properties, but does not disclose the specific structure or evaluation of a sealant film that uses plastic films composed of various materials as recycled materials.

[0011] Therefore, the present inventors have studied recycling plastic films as raw materials for sealant films, and have found that when different types of resins are mixed, resin components other than the resin with the highest content ratio form aggregates, which affect the smoothness and physical properties of the film. If such effects significantly impair the heat sealability and mechanical properties of the film, it becomes difficult to increase the content of recycled plastic in packaging materials.

[0012] The present invention has been made in consideration of the above circumstances, and aims to provide a sealant film, a packaging material, and a packaging bag that have sufficient heat sealability and mechanical properties and enable material recycling of recycled materials containing two or more types of resins. [Means for solving the problem]

[0013] The present invention relates to the following [1] to [8].

[0014] [1] A sealant film comprising a recycled material-containing layer containing a recycled material containing two or more resins, and a sealant layer laminated on one main surface of the recycled material-containing layer, The recycled material-containing layer includes a domain having a smaller transmission brightness than the surrounding area when the sealant film is observed in a planar view, and the domain has a maximum area of ​​1000 μm 2 and a maximum aspect ratio of 10 or less. [2] The sealant film described in [1], wherein the recycled material-containing layer has an average brightness value of 200 or more in HSV color space data and a standard deviation of brightness of 10 or less. [3] The sealant film according to [1] or [2], wherein the sealant layer contains the same type of resin as the resin having the highest content in the recycled material-containing layer. [4] A sealant film according to any one of [1] to [3], further comprising an auxiliary layer laminated on the other main surface of the recycled material-containing layer, the auxiliary layer containing the same type of resin as the resin having the highest content in the recycled material-containing layer. [5] The sealant film according to any one of [1] to [4], wherein the resin having the largest content among the two or more types of resin contained in the recycled material is a polyethylene-based resin or a polypropylene-based resin. [6] A packaging material comprising the sealant film described in any one of [1] to [5]. [7] The packaging material described in [6], wherein the content of plastic material contained in the recycled material is 10 mass% or more based on the total amount of plastic material in the packaging material. [8] A packaging bag made from the packaging material described in [6] or [7]. Effect of the Invention

[0015] According to the present invention, it is possible to provide a sealant film, a packaging material, and a packaging bag that have sufficient heat sealability and mechanical properties and enable material recycling of recycled materials containing two or more types of resins. [Brief description of the drawings]

[0016] [Figure 1]1 is a schematic cross-sectional view showing one embodiment of a sealant film according to the present invention. [Diagram 2] 10 is a schematic diagram for explaining the aspect ratio of a low transmittance lightness region. FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing another embodiment of the sealant film according to the present invention. [Figure 4] 1 is a schematic cross-sectional view showing one embodiment of a laminate according to the present invention. [Diagram 5] 1 is a schematic cross-sectional view showing one embodiment of a packaging material according to the present invention. [Figure 6] FIG. 2 is a schematic cross-sectional view showing another embodiment of a packaging material according to the present invention. [Figure 7] FIG. 2 is a stereomicroscope photograph of the sealant film of Example 1. [Figure 8] FIG. 2 is a stereomicroscope photograph of the sealant film of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments of the present invention will be described in detail. Note that Figs. 1 to 6 are schematic diagrams, and the size and shape of each part are appropriately exaggerated to facilitate understanding. The embodiments shown below are examples of configurations for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited to the materials, shapes, structures, etc. of the components described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims described in the claims.

[0018] <Sealant film> The sealant film of the present embodiment includes a recycled material-containing layer that contains a recycled material that includes two or more types of resin, and a sealant layer laminated on one main surface of the recycled material-containing layer.

[0019] Fig. 1 is a schematic cross-sectional view showing one embodiment of a sealant film. The sealant film 1a shown in Fig. 1 includes a recycled material-containing layer 2 and a sealant layer 3 laminated on one main surface of the recycled material-containing layer 2.

[0020] (Recycled material-containing layer) Examples of recycled materials contained in the recycled material-containing layer include post-consumer recycled (PCR) materials such as bottles and packaging bags for beverages, detergents, and seasonings that have been collected from the market, food containers for lunch boxes and instant noodles, packaging bags for food and garbage bags, plastic products such as hangers, stationery, daily necessities, home appliances, and toys, as well as post-industrial recycled (PIR) materials such as defective products that do not become products discharged from factories, scraps generated during the manufacturing process, and plastic products used for transportation and packaging.

[0021] When the recycled material is a material recycled material, the material recycled material may be washed and crushed as necessary. The material recycled material has the advantage that less energy is required for recycling compared to resin obtained by chemical recycling, which is chemically recycled by pyrolysis or the like. Therefore, the greater the proportion of the material recycled material in the recycled material-containing layer, the smaller the environmental load can be.

[0022] In the sealant film of the present embodiment, from the viewpoint of material recycling of plastic films, a laminate (packaging material) made by bonding a plurality of types of resin sheets, a packaging bag made by making a bag from the laminate, a laminate (packaging material) made by bonding the same types of resin sheets, or a packaging bag made by making a bag from the laminate, or a mixture of these may be used. Examples of packaging bags include refill pouches for toiletries.

[0023] The recycled material contained in the recycled material-containing layer contains two or more resins. The two or more resins include thermoplastic resins, thermosetting resins, and their cured products (including crosslinked products). The two or more resins also include, for example, resin components (such as thermosetting resins) constituting adhesives and their cured products.

[0024] Examples of the thermoplastic resin include polyolefin resin, acrylic resin, polycarbonate resin, polyester resin, polyamide resin, etc. Examples of the thermosetting resin include epoxy resin, polyurethane resin, polyimide resin, etc.

[0025] Examples of polyolefin resins include polyethylene-based resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and ethylene-α-olefin copolymers, as well as polypropylene-based resins such as homopolypropylene (PP), block polypropylene, random polypropylene, and propylene-α-olefin copolymers.

[0026] Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polylactic acid.

[0027] An example of the polyamide resin is nylon 6.

[0028] The two or more resins may include a first resin that is contained in the recycled material at a maximum ratio and a second resin that is incompatible with the first resin or that may form aggregates in the first resin. The type of resin contained in the recycled material-containing layer can be confirmed by a microscope infrared spectrophotometer or the like.

[0029] The first resin and the second resin may be the following combinations. (a) Thermoplastic resins, thermosetting resins and their hardened products (b) Hydrocarbon-based resins and heteroatom-containing resins (c) A resin that dissolves in a specified solvent and a resin that does not dissolve in the specified solvent.

[0030] Examples of the hydrocarbon resin in (b) include polyolefin resins and polystyrene resins, and examples of the heteroatom-containing resin include acrylic resins, polyester resins, and polyamide resins.

[0031] The predetermined solvent in (c) includes aromatic hydrocarbons, chlorinated hydrocarbons, etc. The resin insoluble in the predetermined solvent includes crosslinked resins, cured thermosetting resins, etc.

[0032] The first resin having the highest content in the recycled material may be a polyethylene resin or a polypropylene resin from the viewpoint of recycling packaging bags for pouch products, etc. In this case, the second resin may be, for example, at least one of polyester resin, polyamide resin, and a resin component constituting an adhesive and its cured product.

[0033] The content of the first resin in the recycled material-containing layer may be 75 to 98 mass %, 75 to 95 mass %, or 80 to 90 mass %, based on the total mass of the recycled material-containing layer.

[0034] The content of the second resin in the recycled material-containing layer may be 2 to 33 parts by mass, 5 to 33 parts by mass, or 11 to 25 parts by mass, relative to 100 parts by mass of the first resin.

[0035] The content of recycled material in the recycled material-containing layer may be 13 mass% or more, 33 mass% or more, 50 mass% or more, or 100 mass% based on the total mass of the recycled material-containing layer.

[0036] The resin having the highest content in the recycled material-containing layer may be the same as the resin having the highest content in the recycled material, for example, at least one polyethylene resin selected from the group consisting of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0037] The recycled material-containing layer may contain a virgin material such as a virgin resin. The virgin material may be blended so that the resin with the highest content ratio in the recycled material is the same as the resin with the highest content ratio in the recycled material-containing layer. As the virgin material, for example, the same polyolefin resin as described above can be used, and it may be at least one polyethylene resin selected from the group consisting of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0038] The recycled material-containing layer includes a domain (hereinafter also referred to as a "low transmission brightness region") whose transmission brightness is lower than the surrounding area when the sealant film is observed in a planar view direction, and the domain has a maximum area of ​​1000 μm 2 and the maximum aspect ratio is 10 or less.

[0039] The maximum area and maximum aspect ratio of the low transmittance lightness region are calculated by the following procedure. (i) Using a stereo microscope system SZX16 (product name, manufactured by Olympus Corporation), observation images (image size: 243 μm × 851 μm) are obtained at 10 random locations in the planar direction of the sealant film. (ii) The 10 images obtained are subjected to image analysis using WinROOF2021 (product name, manufactured by Mitani Shoji Co., Ltd.). In the image analysis, the low-transmittance brightness region and the surrounding high-transmittance brightness region are binarized to calculate the area, minimum diameter, and maximum diameter of each low-transmittance brightness region. In addition, when binarizing, the visual shape of the low-transmittance brightness region can be matched with the colored range by appropriately combining the following operations. (a) Adjusting brightness and contrast to emphasize low-transmittance areas (b) Adjust the threshold to match the visible low transmittance area with the colored range. (c) When adjacent low-transmittance brightness areas are recognized as one area, or when low-transmittance brightness areas with holes are recognized as multiple areas, split or merge them as necessary.

[0040] 2 is a schematic diagram for explaining the aspect ratio of a low-transmission lightness region. In FIG. 2, a low-transmission lightness region 20 and a surrounding high-transmission lightness region 30 are shown. The aspect ratio of the low-transmission lightness region 20 is expressed by a maximum diameter (major axis) D L and the minimum diameter (minor axis) D S Compared to D L / D S It should be noted that the minimum value of the aspect ratio is 1, and the shape of the low transmittance lightness area is not limited to an elliptical shape as shown in FIG.

[0041] The maximum area of ​​the low transmittance region determined by the above method is 1000 μm 2 i.e., the area is greater than 1000 μm 2 If there are low-transmittance brightness regions with an aspect ratio of more than 10, local swelling due to the agglomeration occurs on the film surface, resulting in deterioration of heat sealability and mechanical properties. In addition, if there are low-transmittance brightness regions with an aspect ratio of more than 10, the low-transmittance brightness regions will combine with adjacent low-transmittance brightness regions to form pseudo-large-sized agglomerates with an area of ​​1000 μm2 or more. 2 This brings about the same disadvantage as when there is a low transmittance area exceeding 100%.

[0042] In order to conform to general manufacturing equipment and to increase the content of recycled materials in the sealant film, the maximum area of ​​the low transmittance area is 50 μm 2 It may be more than 200 μm 2 It may be more than 400 μm 2 The maximum aspect ratio of the low transmission lightness area may be 6 or more.

[0043] However, when a film in a product form such as a pouch is used as a raw material for a recycled material, a coloring component such as ink may be mixed in. In this case, if the colored portion is localized in the recycled material-containing layer, the appearance defect due to color unevenness becomes significant, and when used as a product, it is necessary to add a white printed layer or a white layer containing a white pigment to form a film. In contrast, according to the sealant film of this embodiment, even if the recycled material contains a coloring component such as ink, the maximum area and maximum aspect ratio of the low transmittance lightness region satisfy the above-mentioned conditions, so that the appearance defect can be suppressed. As a result, compared to when a sealant film is made from only virgin material, the material and process for providing the above-mentioned additional layer are required, and the disadvantage of increased environmental load can be avoided.

[0044] From the same viewpoint as above, it is preferable that the low transmittance lightness regions are dispersed over the entire surface of the recycled material-containing layer rather than being localized, resulting in high uniformity in color tone.

[0045] From the same viewpoint as above, the recycled material-containing layer may have an average brightness of 200 or more and a standard deviation of brightness of 10 or less in HSV color space data.

[0046] The average value and standard deviation of the brightness in the HSV color space data of the recycled material-containing layer are calculated by the following procedure. (i) The sealant film is cut to a size of ±200 mm from the center in the width direction (400 mm width) and 250 mm in the machine direction. (ii) The cut sample is scanned using a digital full-color multifunction printer MP C6503 (manufactured by Ricoh Company, Ltd., product name) under the following reading conditions to obtain an image. [Reading conditions] Type: Full color, text and photos, Resolution: 600, Size: A3 (iii) The obtained image is analyzed using the image analysis software ImageJ to calculate the average brightness value and standard deviation for the entire image. For image analysis, the image saved in TIF format is converted to an HSB stack, and the average value and standard deviation are calculated from the histogram of the V value (brightness) from the histogram analysis results of the HSV color space data. The range of V values ​​is 0 to 255.

[0047] From the viewpoint of adjusting the color tone when the sealant film is used as a transparent packaging material, the recycled material-containing layer may have an average brightness of 210 to 240 and a standard deviation of brightness of 6 or less.

[0048] The recycled material-containing layer may have a thickness of 20 to 80 μm.

[0049] In order to reduce the maximum area and maximum aspect ratio of the low transmittance lightness region in the recycled material-containing layer, for example, the following adjustment means can be mentioned. (a) Reducing the proportion of recycled materials in the recycled material-containing layer (b) Increasing the content of the first resin in the recycled material. (C) When extruding a layer containing recycled material, increase the screw rotation speed. (d) When extruding the recycled material-containing layer, the narrowing of the flow path is avoided as much as possible, and a mechanism is created in which elongation stress is not easily applied. (e) Recycled materials are pelletized using a twin-screw extruder or mixed with virgin resin to form a master batch.

[0050] In order to increase the average brightness in the recycled material-containing layer, for example, the maximum area of ​​the low-transmittance brightness region can be reduced by the above-mentioned adjustment means, etc. In addition, in order to reduce the standard deviation of brightness in the recycled material-containing layer, for example, the resin to be mixed with the recycled material can be selected to increase the fluidity so that the domains forming the low-transparency region are not localized.

[0051] (Sealant layer) Examples of resins that form the sealant layer include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, ethylene vinyl acetate, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyacrylonitrile, polylactic acid, cyclic polyolefin, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, and derivatives thereof. These may be used alone or in combination of two or more.

[0052] From the viewpoint of heat sealability, the sealant layer may contain the same type of resin as the resin with the highest content in the recycled material-containing layer, and virgin resin may be blended to make this the case. For example, when the resin with the highest content in the recycled material-containing layer is a polyethylene-based resin, the sealant layer may contain a polyethylene-based resin, and the polyethylene-based resin may be the main component (for example, the content in the sealant layer is 95% by mass or more). When the resin with the highest content in the recycled material-containing layer is a polypropylene-based resin, the sealant layer may contain a polypropylene-based resin, and the polypropylene-based resin may be the main component (for example, the content in the sealant layer is 95% by mass or more).

[0053] From the viewpoint of processability in film formation, the MFR of the polyethylene resin may be 0.05 to 15 g / 10 min, or 0.1 to 8 g / 10 min. The MFR here refers to a value measured in accordance with JIS K7210 (190°C, load 2.16 kg).

[0054] The MFR of the polypropylene resin may be 0.05 to 20 g / 10 min, or 0.1 to 10 g / 10 min, from the viewpoint of processability in film formation. The MFR here refers to a value measured in accordance with JIS K7210 (230° C., load 2.16 kg).

[0055] From the viewpoint of heat sealability and rigidity, the crystallinity of the polypropylene resin as measured by the heat of fusion using a differential scanning calorimeter (DSC) may be 25% or more and 60% or less, or 30% or more and 55% or less.

[0056] In this specification, the crystallinity of a polypropylene resin is calculated from the ratio of the heat of fusion ΔHm obtained by integrating the endothermic peak when the sample melts to the heat of fusion ΔH100 of a completely crystalline body having a crystallinity of 100% obtained by theoretical calculation, according to the following formula: Crystallinity [%]=(ΔHm / ΔH100)×100 For the heat of fusion ΔH100 of a perfect crystal, the value described in the following document can be used. For example, ΔH100 of polypropylene can be 207 J / g. Reference: The Society of Plastics Processing: Plastic Materials in Molding, 335 (2011), Morikita Publishing Co., Ltd.

[0057] The thickness of the sealant layer may be 20 μm or more, 40 μm or more, or 80 μm or more from the viewpoint of heat sealability, and may be 150 μm or less, 120 μm or less, or 100 μm or less from the viewpoint of reducing the total thickness when used as a packaging material. The thickness of the sealant layer may be 5 μm or more and 60 μm or less, 5 μm or more and 55 μm or less, 5 μm or more and 50 μm or less, 5 μm or more and 40 μm or less, 5 μm or more and 30 μm or less, 5 μm or more and 20 μm or less, 10 μm or more and 65 μm or less, 10 μm or more and 60 μm or less, 10 μm or more and 55 μm or less, 10 μm or more and 50 μm or less, 10 μm or more and 40 μm or less, 10 μm or more and 30 μm or less, 15 μm or more and 60 μm or less, or 20 μm or more and 60 μm or less.

[0058] The recycled material-containing layer and the sealant layer may contain additives such as compatibilizers, nucleating agents, reinforcing fillers, antioxidants, heat stabilizers, weathering agents, light stabilizers, plasticizers, UV absorbers, antistatic agents, flame retardants, flame retardant assistants, slip agents, antiblocking agents, antifogging agents, lubricants, pigments, dyes, dispersants, copper damage inhibitors, neutralizing agents, bubble inhibitors, weld strength improvers, natural oils, synthetic oils, waxes, etc. The additives may be used alone or in combination of two or more.

[0059] Examples of nucleating agents and reinforcing fillers include talc, silica, clay, montmorillonite, calcium carbonate, lithium alumina carbonate, titanium oxide, metals such as aluminum, iron, silver, and copper, hydroxides such as aluminum hydroxide and magnesium hydroxide, celluloses such as cellulose microfibrils and cellulose acetate, fibrous fillers such as glass fibers, polyethylene terephthalate fibers, nylon fibers, polyethylene naphthalate fibers, aramid fibers, vinylon fibers, and polyacrylate fibers, carbons such as carbon nanotubes, and elastomers such as ethylene propylene rubber (EPR).

[0060] Examples of the antioxidant include phenol-based compounds, organic phosphite-based compounds, and thioether-based compounds.

[0061] Examples of the heat stabilizer and light stabilizer include hindered amine compounds.

[0062] Examples of the ultraviolet absorbing agent include benzophenone-based compounds, benzotriazole-based compounds, and benzoate-based compounds.

[0063] The antistatic agent includes nonionic compounds, cationic compounds, anionic compounds, and the like.

[0064] Examples of the flame retardant include halogen-based compounds, phosphorus-based compounds, nitrogen-based compounds, inorganic compounds, boron-based compounds, silicone-based compounds, sulfur-based compounds, and red phosphorus-based compounds.

[0065] Examples of the flame retardant aid include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, and clay silicates.

[0066] Fig. 3 is a schematic cross-sectional view showing another embodiment of the sealant film. The sealant film 1b shown in Fig. 3 includes a recycled material-containing layer 2, a sealant layer 3 laminated on one main surface of the recycled material-containing layer 2, and an auxiliary layer 4 laminated on the other main surface of the recycled material-containing layer 2. In this way, the sealant film of this embodiment may further include an auxiliary layer laminated on the main surface of the recycled material-containing layer opposite to the side on which the sealant layer is laminated.

[0067] When the auxiliary layer 4 is made to function as a laminate layer, it may have the same configuration as the above-mentioned sealant layer 3. The auxiliary layer 4 may contain the same type of resin as the resin having the largest content in the recycled material-containing layer 2. In this case, the higher laminate strength makes it easier to improve adhesion with another layer.

[0068] The auxiliary layer 4 may contain one or more of the above-mentioned additives, if necessary.

[0069] The thickness of the auxiliary layer 4 may be 20 μm or more, 40 μm or more, or 80 μm or more from the viewpoint of the mechanical properties and adhesion of the sealant film, and may be 150 μm or less, 120 μm or less, or 100 μm or less from the viewpoint of reducing the total thickness when used as a packaging material.

[0070] <Method of manufacturing sealant film> The sealant film of the present embodiment can be produced by a conventionally known method. For example, a method of extrusion laminating a recycled material-containing film formed from a resin composition constituting a recycled material-containing layer with a resin composition constituting a sealant layer, or a method of forming a recycled material-containing layer and a sealant layer by co-extrusion molding can be used.

[0071] In the former method, the recycled material-containing film can be produced by melting the resin composition constituting the recycled material-containing layer in an injection molding machine or an extrusion molding machine (e.g., a twin-screw extruder) and then forming the film in a T-die through a feed block or a multi-manifold, or by an inflation method. The recycled material can be produced by collecting, cleaning, and pulverizing various types of plastic waste material, melt-molding the material in an extruder, and pelletizing the material. For extrusion lamination, an extrusion lamination machine or the like can be used.

[0072] In the latter method, for example, a sealant film can be produced by melt-kneading and co-extruding the resin composition constituting the recycled material-containing layer and the resin composition constituting the sealant layer using a multi-layer extrusion molding machine.

[0073] The resin composition constituting the recycled material-containing layer may contain only recycled material, or may further contain virgin resin or additives to impart various desired properties such as viscosity adjustment, mechanical property reinforcement, etc. In addition, when the recycled material and the virgin resin are mixed, they may be dry-blended in which the virgin resin and the recycled material are simultaneously put into a hopper and melt-kneaded to form a film, or may be melt-blended in which the virgin material and the recycled material are separately melt-kneaded in a twin-screw extruder to form a master batch.

[0074] In order to reduce the maximum area and maximum aspect ratio of the low transmittance brightness region in the recycled material-containing layer, the layer may be pelletized using a twin-screw extruder, molded under high shear conditions, or an acid-modified polyolefin resin or the like may be blended as a compatibilizer.

[0075] The film can be cooled in accordance with the molding machine, and for example, in the T-die method, air cooling methods such as an air chamber, a vacuum chamber, and an air knife, and water cooling methods such as dipping a cooling roll in a cold water pan can be used. When providing a surface irregularity by shaping, a method in which molten resin is poured into the contact area between a nip roll processed with silicone rubber, NBR rubber, fluororesin, or the like and a cooling roll processed by cutting metal, with a pressure of 0.1 MPa or more applied, and then cooling can be performed.

[0076] The sealant film may be subjected to a surface modification treatment to improve suitability for post-processing. For example, in order to improve printability and lamination suitability when laminating with other layers or substrate films, a surface modification treatment can be performed on the surface to be laminated. Examples of the surface modification treatment include a method of oxidizing the film surface to express functional groups, such as corona discharge treatment, plasma treatment, and frame treatment, and modification by a wet process, such as coating with an easy-adhesion layer.

[0077] The method for producing the sealant film is not limited to the above-mentioned method, and the sealant film produced by the molding machine may be subjected to in-line or off-line stretching treatment. In addition, there is no restriction on adding other necessary steps or additives as appropriate.

[0078] <Laminate> The laminate of this embodiment includes the sealant film of this embodiment described above. FIG. 4 is a schematic cross-sectional view showing one embodiment of the laminate of this embodiment. The laminate 10a shown in FIG. 4 further includes a gas barrier layer 12 on the side opposite to the recycled material-containing layer 2 side of the auxiliary layer 4 in the sealant film 1b shown in FIG. 3. The laminate 10a can have improved gas barrier properties (e.g., oxygen barrier properties and water vapor barrier properties). The gas barrier layer may have a single layer structure or a laminate structure.

[0079] Examples of the gas barrier layer 12 include a vapor deposition layer (vapor deposition film) made of a metal or inorganic oxide, a metal foil such as aluminum foil, and a film of an ethylene-vinyl alcohol copolymer, a polyamide resin, a polyvinylidene chloride resin, a polyacrylonitrile resin, or the like.

[0080] The vapor-deposited layer may have a single layer structure or a multilayer structure. Examples of the vapor-deposited layer include vapor-deposited layers composed of 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.

[0081] The deposition layer can be formed by a conventionally known method. The formation method can be appropriately selected from physical vapor deposition methods (PVD methods) such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition methods (CVD methods) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition, depending on the deposition material, etc.

[0082] When the deposition layer is an aluminum deposition film, the OD value may be from 2 to 3.5 in terms of productivity, oxygen barrier property, and water vapor barrier property of the laminate. In this specification, the OD value means a value measured in accordance with JIS-K-7361.

[0083] When the deposition layer is an inorganic oxide layer using silicon oxide, the O / Si ratio of the inorganic oxide layer may be 1.5 or more from the viewpoint of transparency. Also, the O / Si ratio may be 2.0 or less from the viewpoint of barrier properties. To obtain the above-mentioned effects more sufficiently, the O / Si ratio of the inorganic oxide layer may be 1.5 or more and 2.0 or less, or 1.6 or more and 1.8 or less.

[0084] The O / Si ratio of the inorganic oxide layer can be determined by X-ray photoelectron spectroscopy (XPS), for example, an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., product name: JPS-90MXV) is used as the measuring device, and the measurement can be performed at an X-ray output of 100 W (10 kV-10 mA) using non-monochromated MgKα (1253.6 eV) as the X-ray source. For quantitative analysis to determine the O / Si ratio, relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p can be used.

[0085] The thickness of the deposition layer may be 1 nm or more and 150 nm or less, 5 nm or more and 60 nm or less, or 5 nm or more and 40 nm or less. When the thickness of the deposition layer is 1 nm or more, oxygen barrier property and water vapor barrier property are easily obtained. When the thickness of the deposition layer is 150 nm or less, it is easy to prevent the occurrence of cracks in the deposition layer and easy to maintain the recyclability of the sealant film.

[0086] The auxiliary layer 4 provided with the gas barrier layer may have the same structure as the above-mentioned sealant layer 3. When the auxiliary layer 4 contains a polyolefin resin, the polyolefin resin preferably has high crystallinity from the viewpoints of printability, vapor deposition suitability, strength, and heat resistance. The polyolefin resin may be a virgin resin.

[0087] When the polyolefin resin is polyethylene, high density polyethylene (HDPE) and medium density polyethylene (MDPE) are preferred from the viewpoints of printability, strength, and heat resistance, and medium density polyethylene is more preferred from the viewpoint of stretchability. When the polyolefin resin is polypropylene, the crystallinity determined by the heat of fusion using a differential scanning calorimeter (DSC) may be 40% or more or 45% or more from the viewpoints of printability, strength, and heat resistance, and may be 60% or less or 55% or less from the viewpoint of impact resistance.

[0088] The content of non-material recycled resin (virgin resin, etc.) in the auxiliary layer 4 on which the gas barrier layer is provided can be made higher than the content of non-material recycled resin in the recycled material-containing layer. In this case, partial swelling due to aggregates on the surface of the recycled material-containing layer can be smoothed, and the mechanical properties and gas barrier properties of the laminate can be improved.

[0089] The thickness of the auxiliary layer 4 on which the gas barrier layer is provided may be 20 μm or more, 40 μm or more, or 80 μm or more from the viewpoints of gas barrier properties and adhesion, and may be 150 μm or less, 120 μm or less, or 100 μm or less from the viewpoint of reducing the total thickness when used as a packaging material.

[0090] <Packaging material> The packaging material of this embodiment includes the sealant film of this embodiment described above. Fig. 5 is a schematic cross-sectional view showing one embodiment of the packaging material. The packaging material 100 shown in Fig. 5 includes a sealant film 1b including an auxiliary layer 4, and a base film 6 laminated onto the auxiliary layer 4 via an adhesive layer 5.

[0091] The base film 6 is not particularly limited as long as it has mechanical strength and dimensional stability, and may be a plastic film, paper, nonwoven fabric, etc. Constituent materials for the plastic film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, polystyrene, polyamides such as 6-nylon, polycarbonate, polyacrylonitrile, polyimide, etc.

[0092] From the viewpoints of mechanical strength and dimensional stability, the base film 6 is preferably a stretched film.

[0093] By containing the same type of resin (also called "same resin") as the resin with the highest content in the sealant film, the entire packaging material can be made into a mono-material, improving the recyclability of the packaging material. In this case, all layers constituting the sealant film (for example, the sealant layer, or the sealant layer and the auxiliary layer) may contain the same type of resin as the resin with the highest content in the recycled material-containing layer.

[0094] The content of the same resin in the packaging material may be 90% by mass or more based on the total amount of the packaging material. In this case, the packaging material may be said to be a mono-material packaging material made of a single material. From the viewpoint of further improving recyclability, the content of the same resin in the packaging material may be 92.5% by mass or more, or may be 95% by mass or more based on the total amount of the packaging material.

[0095] From the viewpoint of transparency, the haze value of the base film 6 may be 30% or less, or may be 20% or less. In this specification, the haze value of the film means a value measured in accordance with JIS K 7105.

[0096] The substrate film 6 may be subjected to a surface treatment. In this case, the adhesion with the adjacent layers can be improved. The method of the surface treatment is not particularly limited, and examples thereof include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, and glow discharge treatment, and chemical treatments such as oxidation treatment using chemicals.

[0097] An anchor coat layer may be provided on the surface of the base film 6 using a conventionally known anchor coat agent.

[0098] The thickness of the base film 6 may be 10 μm or more and 50 μm or less, or 12 μm or more and 30 μm or less. When the thickness of the base film is 10 μm or more, it is easy to improve the strength of the packaging material. Also, when the thickness of the base film is 50 μm or less, it is easy to maintain the processability of the packaging material.

[0099] The adhesive layer 5 is a layer that bonds the base film 6 and the sealant film. In the packaging material 100, the auxiliary layer 4 of the sealant film and the base film 6 are bonded via the adhesive layer 5.

[0100] The adhesive constituting the adhesive layer is not particularly limited, but a dry lamination adhesive can be used. Examples of the dry lamination adhesive include a two-component curing urethane adhesive, a polyester urethane adhesive, a polyether urethane adhesive, an acrylic adhesive, a polyester adhesive, a polyamide adhesive, and an epoxy adhesive.

[0101] When the packaging material is used for a packaging bag for retort use, a two-component curing urethane adhesive having retort resistance can be used.

[0102] From the viewpoint of environmental consideration, the adhesive layer 5 may satisfy at least one of the following conditions. (1) Does not contain 3-glycidyloxypropyltrimethoxysilane (GPTMS). (2) Includes biomass materials. (3) Contains no solvents.

[0103] The adhesive layer 5 may be chlorine-free from the viewpoint of suppressing discoloration of the recycled resin after recycling and generation of odor due to heat treatment.

[0104] The thickness of the adhesive layer may be 0.3 μm or more and 5.0 μm or less. From the viewpoint of adhesive strength expression, the thickness of the adhesive layer may be 0.3 μm or more, 0.5 μm or more, or 1 μm or more, and from the viewpoint of recyclability, the thickness may be 5.0 μm or less, 3.5 μm or less, or 2.5 μm or less. When the thickness of the adhesive layer is equal to or less than the above upper limit, the ratio of monomaterials in the packaging material can be increased.

[0105] The packaging material of the present embodiment may further include a functional layer such as a print layer and a gas barrier layer. These functional layers may be provided on the above-mentioned base film.

[0106] The printed layer may be formed on the surface of the base film on which the sealant film is provided. In this case, the printed layer can be prevented from coming into contact with the outside air, and deterioration over time can be prevented.

[0107] The printed layer may represent characters, patterns, symbols, combinations thereof, and the like.

[0108] From the viewpoint of producing a packaging material with less environmental impact, the printed layer may be formed using ink derived from biomass.

[0109] The method for forming the printed layer is not particularly limited, and any conventionally known printing method such as gravure printing, offset printing, flexographic printing, etc. Among these, flexographic printing may be used from the viewpoint of environmental load.

[0110] The gas barrier layer can be provided on a substrate film, and may have the same structure as the gas barrier layer 12 described above.

[0111] The gas barrier layer may be provided by laminating a laminate film of a metal foil and a plastic film, or a vapor deposition film having a vapor deposition layer (vapor deposition film) made of the above-mentioned metal or inorganic oxide on a plastic film. Examples of the plastic film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, polystyrene, polyamides such as 6-nylon, polycarbonate, polyacrylonitrile, polyimide, etc.

[0112] Fig. 6 is a schematic cross-sectional view showing another embodiment of a packaging material. The packaging material 102 shown in Fig. 6 includes a laminate 10a in which a sealant film 1b having a laminated structure of a sealant layer 3, a recycled material-containing layer 2, and an auxiliary layer 4, and a gas barrier layer 12 are laminated in this order, and a base film 6 having a printed layer 7 bonded to the gas barrier layer 12 side of the laminate via an adhesive layer 5. In the packaging material 102, as described above, the printed layer 7 is formed on the surface of the base film 6 on the side where the sealant film is provided.

[0113] Each layer in the packaging material of the present embodiment may contain the additives described above.

[0114] The packaging material of the present embodiment can be modified in various ways in addition to the configuration described above, and may have the following configuration. (a) Sealant film of this embodiment / adhesive layer / gas barrier film / adhesive layer / base film (b) Sealant film / adhesive layer / gas barrier film of this embodiment (c) Sealant film of this embodiment / gas barrier layer (e.g., vapor deposition layer) / adhesive layer / substrate film The gas barrier film may be a base film provided with a gas barrier layer, a laminate film of a metal foil and a plastic film, or a vapor-deposited film, as described above, or may be a metal foil such as aluminum foil, or a film such as an ethylene-vinyl alcohol copolymer, a polyamide resin, a polyvinylidene chloride resin, or a polyacrylonitrile resin.

[0115] The packaging material may also comprise a sealant film having an auxiliary layer, a first base film laminated onto the auxiliary layer via an adhesive layer, and a second base film having a printing layer laminated onto the first base film via the adhesive layer.

[0116] From the viewpoint of material recycling, the content of plastic materials contained in the packaging material of the present embodiment may be 10% by mass or more, or 25% by mass or more, based on the total amount of plastic materials in the packaging material. When the packaging material of the present embodiment is a laminate packaging material, materials other than plastics (e.g., adhesives, printing inks, aluminum foil, etc.) may be excluded from the weight calculation.

[0117] The plastic material contained in the recycled material (so-called recycled plastic) may be the resin contained in the recycled material contained in the recycled material-containing layer according to the present embodiment described above. The weight of pre-consumer materials in the recycled plastic may be calculated by multiplying the weight by 1 / 2.

[0118] The packaging material of this embodiment can be used for a standing pouch, a three-sided bag, a folded bag, a gusseted bag, a pouch with a spout, a pouch with a beak, and the like.

[0119] <Packaging bag> The packaging bag of this embodiment is made from the packaging material of this embodiment described above. The manufacturing style of the packaging bag is not particularly limited, but the packaging bag may be a standing pouch, a three-sided bag, a palm-shaped bag, a gusset bag, a pouch with a spout, a pouch with a beak, or the like. EXAMPLES

[0120] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0121] <Preparing recycled materials> (Recycled material 1) A film in which an LLDPE film (manufactured by Mitsui Chemicals Tocello, product name "TUX FC-S", film thickness 100 μm), an adhesive layer, a PET film (manufactured by Toray Film Processing, product name "VM-PET 1310", film thickness 12 μm, aluminum vapor deposition), an adhesive layer, a printing layer, and an Ny film (manufactured by Toyobo, product name "Harden Film N1100", film thickness 15 μm) were laminated in this order was compressed, cut, and formed into granules to obtain recycled material 1. The adhesive layer was formed by dry lamination using an adhesive made by mixing Dick Dry LX-500 (manufactured by DIC Graphics, product name) as the main agent, KW75 (manufactured by DIC Graphics, product name) as the hardener, and NC401 (manufactured by Toyo Ink, product name) as the solvent.

[0122] (Recycled material 2) A film consisting of a PP film (manufactured by Toray Film Processing Co., Ltd., product name "Torayfan NO ZK207", film thickness 100 μm), an adhesive layer, a PET film (manufactured by Toray Film Processing Co., Ltd., "VM-PET 1310", film thickness 12 μm, aluminum vapor deposition), an adhesive layer, a printed layer, and a Ny film (manufactured by Toyobo Co., Ltd., product name "Harden Film N1100", film thickness 15 μm) laminated in this order was compressed, cut, and formed into granules to obtain recycled material 2. The adhesive layer was formed in the same manner as recycled material 1.

[0123] (Recycled material 3) Recycled material 3 was obtained by compressing, cutting, and shaping into granules a film consisting of an LLDPE film (manufactured by Mitsui Chemicals Tocello, product name "TUX FC-S", film thickness 100 μm), an adhesive layer, an HDPE film (manufactured by Tamapoly, product name "HF31", film thickness 35 μm), an adhesive layer, a printed layer, and an HDPE film (manufactured by Tamapoly, product name "HF31", film thickness 35 μm) laminated in that order. The adhesive layer was formed in the same manner as recycled material 1.

[0124] <Preparation of sealant film> Example 1 The recycled material 1 and LLDPE (Prime Polymer Co., Ltd., product name "Evolue SP2040") were put into the hopper extruding the recycled material-containing layer in a weight ratio of 1:1, and LLDPE (Prime Polymer Co., Ltd., product name "Evolue SP2040") was put into the hopper extruding the sealant layer, and a single-screw multi-layer extruder was used to co-extrude the recycled material-containing layer with a thickness of 80 μm and the sealant layer with a thickness of 20 μm to produce a sealant film. The screw rotation speed when extruding the recycled material-containing layer was 16 rpm, and the narrowing of the flow path in front of the T-die was avoided as much as possible, making it a mechanism that is less susceptible to elongation stress.

[0125] Example 2 A sealant film was produced in the same manner as in Example 1, except that only recycled material 1 was placed in the hopper for extruding the recycled material-containing layer.

[0126] Example 3 A sealant film was produced in the same manner as in Example 2, except that recycled material 2 was placed in the hopper extruding the recycled material-containing layer instead of recycled material 1, and block polypropylene resin (bPP) (manufactured by Japan Polypropylene Corporation, product name "Novatec PP BC6DRF") was used in the hopper extruding the sealant layer.

[0127] Example 4 A sealant film was produced in the same manner as in Example 2, except that recycled material 2 was charged instead of recycled material 1 into the hopper for extruding the recycled material-containing layer.

[0128] Example 5 A sealant film was produced in the same manner as in Example 1, except that recycled material 3 and LLDPE (manufactured by Prime Polymer, product name "Evolue SP2040") were added to the hopper for extruding the recycled material-containing layer in a weight ratio of 1:1.

[0129] Example 6 A sealant film was produced in the same manner as in Example 2, except that recycled material 3 was charged instead of recycled material 1 into the hopper for extruding the recycled material-containing layer.

[0130] Example 7 Only the recycled material 1 was put into the hopper extruding the recycled material-containing layer, LLDPE (manufactured by Prime Polymer, product name "Evolue SP2040") was put into the hopper extruding the sealant layer, and LLDPE (manufactured by Prime Polymer, product name "Evolue SP2040") was put into the hopper extruding the auxiliary layer, and a sealant film was produced by co-extrusion molding using a single-screw multi-layer extruder to produce a 20 μm-thick auxiliary layer, an 80 μm-thick recycled material-containing layer, and a 20 μm-thick sealant layer in that order. The screw rotation speed when extruding the recycled material-containing layer was 16 rpm, and the narrowing of the flow path in front of the T-die was avoided as much as possible, making it a mechanism that is less susceptible to elongation stress.

[0131] (Reference example 1) A commercially available PE sealant film (manufactured by Tamapoly Co., Ltd., product name "MZ434") was prepared.

[0132] Comparative Example 1 A sealant film was produced in the same manner as in Example 1, except that an orifice was inserted before the T-die to apply an elongation stress when extruding the recycled material-containing layer.

[0133] Comparative Example 2 A sealant film was produced in the same manner as in Example 2, except that the screw rotation speed was reduced to 10 rpm when extruding the recycled material-containing layer.

[0134] Comparative Example 3 A sealant film was produced in the same manner as in Example 3, except that when extruding the recycled material-containing layer, the screw rotation speed was reduced to 10 rpm and an orifice was inserted before the T-die to apply an elongational stress.

[0135] Comparative Example 4 A sealant film was produced in the same manner as in Example 4, except that when extruding the recycled material-containing layer, the screw rotation speed was reduced to 10 rpm and an orifice was inserted before the T-die to apply an elongational stress.

[0136] Comparative Example 5 A sealant film was produced in the same manner as in Example 5, except that the screw rotation speed was reduced to 10 rpm when extruding the recycled material-containing layer.

[0137] Comparative Example 6 A sealant film was produced in the same manner as in Example 6, except that an orifice was inserted before the T-die to apply an elongation stress when extruding the recycled material-containing layer.

[0138] <Analysis of layers containing recycled materials> (Maximum area and maximum aspect ratio of low transmittance area) The maximum area and maximum aspect ratio of the low transmittance lightness region in the recycled material-containing layer were calculated by the following procedure. (i) Using a stereo microscope system SZX16 (product name, manufactured by Olympus Corporation), observation images (image size: 243 μm × 851 μm) were taken at 10 random locations in the planar direction of the sealant film. (ii) The 10 images obtained were subjected to image analysis using WinROOF2021 (product name, manufactured by Mitani Shoji Co., Ltd.). In the image analysis, the low-transmittance lightness region and the surrounding high-transmittance lightness region were binarized, and the following operations were appropriately performed during the binarization to match the visual shape of the low-transmittance lightness region with the colored range. (a) Adjusting brightness and contrast to emphasize low-transmittance areas (b) Adjust the threshold to match the visible low transmittance area with the colored range. (c) When adjacent low-transmittance brightness areas are recognized as one area, or when low-transmittance brightness areas with holes are recognized as multiple areas, split or merge them as necessary.

[0139] Fig. 7 is a stereomicroscope photograph of the sealant film of Example 1. Fig. 8 is a stereomicroscope photograph of the sealant film of Comparative Example 1.

[0140] (Average and standard deviation of brightness) The average value and standard deviation of the brightness in the HSV color space data of the recycled material-containing layer were calculated by the following procedure. (i) The sealant film was cut to a size of ±200 mm from the center in the width direction (400 mm width) and 250 mm in the machine direction. (ii) The cut sample was scanned using a digital full-color multifunction printer MP C6503 (manufactured by Ricoh Company, Ltd., product name) under the following reading conditions to obtain an image. [Reading conditions] Type: Full color, text and photos, Resolution: 600, Size: A3 (iii) The obtained image was analyzed using the image analysis software ImageJ, and the average brightness value and standard deviation for the entire image were calculated. For image analysis, the image saved in TIF format was converted to an HSB stack, and the average value and standard deviation were calculated from the histogram of the V value (brightness) from the histogram analysis results of the HSV color space data. The range of V values ​​is 0 to 255.

[0141] <Evaluation of sealant film> (Heat seal strength) The sealant film layer sides of two sealant films were overlapped, heat-sealed at a width of 20 mm, leaving 10 mm at the end, and both long side ends were cut off by 5 mm to prepare a 10 mm wide test piece. The heat-sealing temperature was changed by 10°C increments in the range of 120 to 180°C. For each test piece, a Tensilon universal testing machine RTG-1310 (manufactured by A&D Co., Ltd., product name) was used, and the unsealed 10 mm parts were attached to the upper and lower chucks and pulled at 100 mm / min. At this time, regardless of the heat-sealing temperature, if a strength equal to or greater than that of a commercially available sealant film (Reference Example 1) was obtained, it was evaluated as "◎", if the strength was less than that of the commercially available sealant film but the test piece broke, it was evaluated as "◯", and if interfacial peeling or cohesive failure occurred, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0142] (Breaking strength) A test piece measuring 15 mm x 25 mm was cut from the sealant film so that the long side was in the film production flow direction. The test piece was placed in a Tensilon universal testing machine RTG-1310 (manufactured by A&D Co., Ltd., product name) with a chuck distance of 20 mm and pulled at 100 mm / sec. If the test piece showed an elongation equal to or greater than that of a commercially available sealant film (Reference Example 1), it was evaluated as "Good", and if it did not reach that of the commercially available sealant film, it was evaluated as "Poor". The results are shown in Tables 1 and 2.

[0143] (Appearance 1) A laminate was obtained by providing a laminate structure of an adhesive layer, a PET film (manufactured by Toyobo Co., Ltd., E5202, film thickness 12 μm), an adhesive layer, a printed layer, and a Ny film (manufactured by Toyobo Co., Ltd., product name "Harden Film N1100", film thickness 15 μm) on the surface opposite to the sealant layer of the sealant film. On the other hand, a laminate structure similar to the above was provided on a commercially available sealant film (Reference Example 1) to obtain a comparative laminate. When the laminate had the same appearance (color) as the comparative laminate, it was evaluated as "◯", and when the appearance (color) seemed to be different from the comparative laminate, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0144] (Appearance 2) A laminate was obtained by providing a laminate structure of an adhesive layer, a PET film (manufactured by Toray Film Processing Co., Ltd., "VM-PET 1310", film thickness 12 μm, aluminum vapor deposition), an adhesive layer, a printed layer, and a Ny film (manufactured by Toyobo, product name "Harden Film N1100", film thickness 15 μm) on the surface opposite to the sealant layer of the sealant film. On the other hand, a laminate structure similar to the above was provided on a commercially available sealant film (Reference Example 1) to obtain a comparative laminate. If the laminate had the same appearance (surface smoothness (lack of unevenness)) as the comparative laminate, it was evaluated as "◎", if the appearance (surface smoothness (lack of unevenness)) was inferior to the comparative laminate but there was no problem in practical use, it was evaluated as "◯", and if there was a problem in practical use, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0145] [Table 1]

[0146] [Table 2]

[0147] As shown in Table 1, the sealant films of Examples 1 to 7 had heat seal strength and breaking elongation equal to or greater than those of commercially available sealant films, and it was confirmed that they had sufficient heat sealability and mechanical properties while containing recycled materials.

[0148] In addition, according to the sealant films of Examples 1 to 7, even though the recycled material contains a printed layer, a laminate having an appearance equal to or better than that of a laminate produced using a commercially available sealant film can be obtained, so that the materials and steps for providing an additional layer for concealing defective appearance can be omitted. As a result, it was confirmed that the present invention can realize a packaging material that uses recycled materials while suppressing costs and environmental burdens. [Explanation of symbols]

[0149] Reference Signs List: 1a, 1b... sealant film, 2... recycled material-containing layer, 3... sealant layer, 4... auxiliary layer, 5... adhesive layer, 6... base film, 7... printed layer, 10a... laminate, 12... gas barrier layer, 20... low transmittance brightness region (aggregate), 30... high transmittance brightness region, 100, 102... packaging material.

Claims

1. A sealant film comprising a recycled material-containing layer containing a recycled material containing two or more types of resins, and a sealant layer laminated on one main surface of the recycled material-containing layer, The recycled material-containing layer includes a domain having a smaller transmission lightness than the surrounding area when the sealant film is observed in a planar view direction, The domain has a maximum area of ​​1000 μm ２ and the maximum aspect ratio is 10 or less; The sealant layer contains the same type of resin as the resin having the highest content in the recycled material-containing layer. Sealant film.

2. 2. The sealant film according to claim 1, wherein the recycled material-containing layer has an average brightness value of 200 or more and a standard deviation of brightness of 10 or less in HSV color space data.

3. Further comprising an auxiliary layer laminated on the other main surface of the recycled material-containing layer, The sealant film according to claim 1 , wherein the auxiliary layer contains the same type of resin as the resin having the highest content in the recycled material-containing layer.

4. The sealant film according to claim 1 , wherein the resin having the largest content ratio among the two or more types of resin contained in the recycled material is a polyethylene-based resin or a polypropylene-based resin.

5. A packaging material comprising the sealant film according to any one of claims 1 to 4.

6. 6. The packaging material according to claim 5, wherein the content of plastic material contained in the recycled material is 10 mass% or more based on the total amount of plastic material in the packaging material.

7. A packaging bag made from the packaging material according to claim 5.

8. A packaging bag made from the packaging material according to claim 6.

Images