Sealant films, packaging materials and packaging bags

Abstract

To provide a sealant film, a packaging material and a packaging bag which have sufficient reliability and film production property during heat sealing, while containing a recycled material containing two or more kinds of resins.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 arithmetic surface roughness of a surface S3a on a side opposite to the side of the recycled material-containing layer 2 of the sealant layer 3 is 0.5 μm or more and 5 μm 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 several types of them are layered to form a laminate. Also, several plastic materials are mixed in one layer to compensate for the shortcomings of a single material.

[0004] Recycling of plastic products is expected to be a part of efforts to address environmental issues, and various recycling methods are being considered. For example, technology has been established for material recycling, in which collected PET bottles are washed and crushed for reuse as raw materials, and chemical recycling, in which the products are converted into monomers.

[0005] As a method for recycling polyethylene materials, the use of recycled polyethylene for applications such as films has been considered. For example, Patent Document 1 below proposes a sealant film containing recycled polyethylene resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2022 / 124229 Summary of the Invention [Problem to be solved by the invention]

[0007] Some recycled materials contain different types of resins. The present inventors have investigated recycling such recycled materials as raw materials for sealant films, and have found that a sealant film having a layer containing a recycled material may have a reduced reliability during heat sealing.

[0008] On the other hand, film products such as sealant films are required to have the property of being able to be molded without the occurrence of creases or wrinkles from the stage of film formation to winding (hereinafter also referred to as "film formability"). If the film has insufficient film formability, the film after winding is likely to have poor appearance due to creases or wrinkles.

[0009] 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 contain recycled materials containing two or more types of resins and have sufficient reliability during heat sealing and film-formability. [Means for solving the problem]

[0010] In order to solve the above problems, the present inventors have investigated factors that reduce reliability during heat sealing, and have found that when different types of resins are mixed in a layer containing recycled material, aggregates are formed by resin components other than the resin with the largest content ratio, and when these aggregates cause excessively large protrusions on the sealant film surface, air entrapment occurs during heat sealing. Based on this knowledge, the present inventors have further investigated and found that a sealant film prepared so that the surface roughness of the sealant layer meets specific conditions can solve the above problems, leading to the completion of the present invention.

[0011] One aspect of the present invention relates to the following [1] to [9].

[0012] [1] A sealant film comprising a recycled material-containing layer containing 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, wherein the arithmetic surface roughness of the surface of the sealant layer opposite to the recycled material-containing layer is 0.5 μm or more and 5 μm or less. [2] The sealant film described in [1], wherein the thickness of the sealant layer is 5 μm or more and 70 μm or less. [3] The sealant film according to [1] or [2], wherein the maximum height H of the convex portions on the surface of the sealant layer is 0.5 μm or more and 10 μm or less, and the ratio [W / H] of the width W at half the maximum height H to the maximum height H of the convex portions having the maximum height H is 20 or less. [4] The sealant film according to any one of [1] to [3], 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. [5] The sealant film according to any one of [1] to [4], further comprising an auxiliary layer laminated on the other main surface of the recycled material-containing layer. [6] The sealant film described in [5], wherein the auxiliary layer contains the same type of virgin resin as the resin with the highest content in the recycled material-containing layer. [7] A packaging material comprising the sealant film described in any one of [1] to [6]. [8] The packaging material described in [7], 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. [9] A packaging bag made from the packaging material described in [7] or [8]. Effect of the Invention

[0013] According to the present invention, it is possible to provide a sealant film, a packaging material, and a packaging bag that contain recycled materials containing two or more types of resins and have sufficient reliability during heat sealing and film-formability. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view showing one embodiment of a sealant film according to the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view for explaining the shape of a convex portion in the sealant film shown in 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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.

[0016] <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.

[0017] 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.

[0018] (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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polylactic acid.

[0025] An example of the polyamide resin is nylon 6.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] The predetermined solvent in (c) may be an aromatic hydrocarbon, a chlorinated hydrocarbon, etc. The resin that dissolves in the predetermined solvent may be an uncrosslinked resin, etc. The resin that does not dissolve in the predetermined solvent may be a crosslinked resin, a cured thermosetting resin, etc.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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).

[0035] 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).

[0036] The recycled material-containing layer may contain aggregates derived from the second resin, for example, and from the viewpoint of ensuring reliability during heat sealing, the aggregates may have a maximum diameter of 20 μm or less. If the maximum diameter of the aggregates is 20 μm or less, it becomes easier to prevent the occurrence of convex portions having a height of more than 10 μm or convex portions having a height of 0.5 μm to 10 μm and a width-to-height ratio at half the height of more than 20 on the surface of the sealant layer.

[0037] The recycled material-containing layer may contain aggregates having a maximum diameter of 40 μm to 100 μm, 50 μm to 90 μm, or 60 μm to 80 μm.

[0038] The agglomerates and their maximum diameters can be confirmed by the following method. The aggregates contained in the recycled material-containing layer can be confirmed as domains (hereinafter also referred to as "low transmission brightness regions") having a lower transmission brightness than the surrounding area when the sealant film is observed through transmission from a direction in which the sealant film is viewed in a plane, and the maximum diameter of the low transmission brightness region can be obtained 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 transmission brightness area and the surrounding high transmission brightness area are binarized to calculate the maximum diameter in each low transmission brightness area. In addition, when binarizing, the visual shape of the low transmission brightness area and the colored range can be matched 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.

[0039] In order to reduce the maximum diameter of the aggregates 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.

[0040] The recycled material-containing layer may have a thickness of 20 to 100 μm.

[0041] (Sealant layer) The sealant layer has an uneven surface on the side opposite to the recycled material-containing layer. 3a) has an arithmetic surface roughness Ra of 0.5 μm or more and 5 μm or less as specified in JIS B 0601:2001. When Ra is 5 μm or less, it is possible to suppress a decrease in reliability (for example, a decrease in low-temperature heat sealability) due to air entrapment when overlapping sealant films and heat sealing them. In addition, the thickness of the recessed portion becomes locally thin, and defects such as a decrease in impact resistance and puncture resistance are unlikely to occur. On the other hand, when Ra is 0.5 μm or more, the friction coefficient is not too large, and appropriate slipperiness can be obtained, making it difficult for wrinkles to occur during film formation.

[0042] From the above viewpoint, the Ra may be 0.5 μm or more and 4 μm or less, 0.5 μm or more and 3 μm or less, 0.5 μm or more and 2 μm or less, 0.5 μm or more and 1.5 μm or less, 1.0 μm or more and 4 μm or less, 1.0 μm or more and 3 μm or less, or 1.0 μm or more and 2 μm or less.

[0043] Methods for adjusting the Ra include, in addition to adjusting the maximum diameter of the aggregates described above, changing the thickness of the sealant layer, incorporating an antiblocking agent into the sealant layer, and forming a predetermined unevenness on the surface of the sealant layer (for example, pressing a nip roll against the molten resin when cooling and solidifying it during film formation).

[0044] From the viewpoint of ensuring reliability during heat sealing, the above surface of the sealant layer (S shown in FIG. 2) 3a ) in the convex part (P shown in Fig. 2 3a ) is the height (H 3a From the same viewpoint, the width at half the height of the protrusion (W shown in FIG. 2) may be 10 μm or less, 0.5 to 9 μm, or 0.5 to 8 μm. 3a ) may be 200 μm or less, may be 1 to 150 μm, or may be 1 to 100 μm. FIG. 2 is a schematic cross-sectional view for explaining the shape of the protrusions in the sealant film shown in FIG. 1. As shown in FIG. 2, the protrusions P 3aThe surface S of the sealant layer 3 is formed by the aggregates 50 generated in the recycled material-containing layer. 3a It may also be caused by a rise in

[0045] The convex portions on the surface of the sealant layer may have a maximum height H of 0.5 μm or more and 10 μm or less, and the convex portions having the maximum height H may have a ratio [W / H] of the width W at half the maximum height H to the maximum height H of 20 or less, or the above H may be 0.5 to 9 μm and the ratio [W / H] may be 1 to 18. In this case, it is advantageous in terms of (a) improving the content of recycled material in the recycled material-containing layer, (b) improving the content of recycled material in the sealant film by reducing the thickness of the sealant layer, and (c) improving productivity by being able to reduce the pressure applied during cooling or hot pressing during film formation.

[0046] As a material for forming the sealant layer, a material having suitable flexibility and good processability, such as suitability for processing by an extruder, such as a thermoplastic resin, can be used. Examples of such materials include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polypropylene having a homopolymer, random copolymer, or block copolymer, ethylene-vinyl acetate copolymer obtained by copolymerizing olefin such as low-density polyethylene (LDPE) with vinyl acetate, ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), and ethylene-methacrylic acid copolymer (EMAA) obtained by modifying the side chain of olefin, etc. These may be used alone or in combination of two or more.

[0047] 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. 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, or 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, or the polypropylene-based resin may be the main component (for example, the content in the sealant layer is 95% by mass or more).

[0048] The sealant layer may contain a polypropylene resin from the viewpoint of reducing the above-mentioned maximum height H and the ratio [W / H].

[0049] 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).

[0050] 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).

[0051] 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.

[0052] 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.

[0053] The sealant layer may contain the above resin as a virgin material, or may contain no recycled material from the viewpoint of the stability of the heat sealability.

[0054] The thickness of the sealant layer may be 5 μm or more and 70 μm or less. In this case, it is easy to prevent the aggregate contained in the recycled material-containing layer from being exposed from the sealant layer, and it is easy to ensure the rigidity of the entire sealant film and to increase the content of recycled material in the sealant film. This makes it possible to more effectively realize material recycling of recycled materials containing two or more types of resins in the sealant film. 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.

[0055] 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.

[0056] 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).

[0057] Examples of the antioxidant include phenol-based compounds, organic phosphite-based compounds, and thioether-based compounds.

[0058] Examples of the heat stabilizer and light stabilizer include hindered amine compounds.

[0059] Examples of the ultraviolet absorbing agent include benzophenone-based compounds, benzotriazole-based compounds, and benzoate-based compounds.

[0060] The antistatic agent includes nonionic compounds, cationic compounds, anionic compounds, and the like.

[0061] 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.

[0062] Examples of the flame retardant aid include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, and clay silicates.

[0063] Examples of the anti-blocking agent include acrylic particles, styrene particles, styrene acrylic particles and crosslinked products thereof, polyurethane particles, polyester particles, silicon particles, fluorine particles, copolymers thereof, zeolite, pyrophyllite, talc, smectite, vermiculite, mica, chlorite, kaolin minerals, clay compound particles such as sepiolite, silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, strontium oxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, strontium nitrate, strontium hydroxide, and glass particles.

[0064] In the sealant film of the present embodiment, the ratio Tr / Ts of the thickness Tr of the recycled material-containing layer to the thickness Ts of the sealant layer may be 0.3-16, 0.5-14, or 0.7-12.

[0065] The sealant film of this embodiment may have a multi-layer structure in which desired physical properties are complemented by laminating another layer. 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 case, the surface S of the sealant layer 3 opposite to the recycled material-containing layer 2 side is also laminated on the other main surface of the recycled material-containing layer 2. 3b The arithmetic surface roughness Ra defined in JIS B 0601:2001 can satisfy the above-mentioned conditions.

[0066] The auxiliary layer 4 may be configured to contain a high-density resin in order to further increase the rigidity of the sealant film 1b, and may be configured to contain a resin having a density similar to that of the resin constituting the sealant layer 3 (for example, a density difference of 0.1 kg / m 2 in order to suppress curling due to thermal shrinkage of the sealant film 1b). 3The resin may be formed by including a resin having the following properties.

[0067] When the auxiliary layer 4 is made to function as a laminate layer, it may have the same structure 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 the adhesion with another layer.

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

[0069] Furthermore, when auxiliary layer 4 is made to function as a laminate layer, the arithmetic surface roughness Ra defined in JIS B 0601:2001 of the surface of auxiliary layer 4 opposite to recycled material-containing layer 2 may be 0.03 μm or more and 5 μm or less, 0.04 μm or more and 3 μm or less, or 0.05 μm or more and 2 μm or less. In this case, when another layer is laminated on the laminate layer via an adhesive, it becomes easy to suppress lamination defects caused by defective areas where the adhesive does not adhere.

[0070] The Ra of the auxiliary layer 4 can be adjusted by changing the thickness of the auxiliary layer 4. In this case, the thickness of the auxiliary layer may be 5 μm or more and 100 μm or less, 10 μm or more and 90 μm or less, or 20 μm or more and 80 μm or less, from the viewpoints of suppressing lamination defects and suppressing costs.

[0071] <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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] From the viewpoint of reducing the size of aggregates in the recycled material-containing layer, pelletizing using a twin-screw extruder, molding under high shear conditions, or blending with an acid-modified polyolefin resin or the like as a compatibilizer may be performed.

[0076] The film can be cooled using a method that is compatible with the molding machine. For example, in the T-die method, air-cooling methods such as an air chamber, vacuum chamber, or air knife, or water-cooling methods such as dipping a cooling roll in a cold water pan can be used.

[0077] In the case of the T-die method, for example, in order to adjust the Ra of the sealant layer, when the molten resin is cooled and solidified using a cooling roll having a predetermined surface shape, the sealant layer can be shaped with a predetermined surface shape by pressing it with a nip roll. As a means for imparting a surface shape by shaping, a method of pouring a molten resin into a contact part between a nip roll processed with silicone rubber, NBR rubber, fluororesin, or the like and a cooling roll, to which a pressure of 0.1 MPa or more is applied, and cooling may be performed. The cooling roll may be one obtained by cutting a metal or one given a shape by blasting. The surface shape of the cooling roll may be a random uneven shape, and the surface roughness can be adjusted by changing the particle size or processing time (amount) during blasting. The Ra of the auxiliary layer can also be adjusted in the same manner as above.

[0078] The sealant film of the present embodiment can also be produced by a method using heat pressing. In the method using heat pressing, a flat film can be molded by compressing it between heated rolls or with a heated flat plate. The thickness of the molded product can be controlled by adjusting the pressure to be compressed at this time. A single layer of film produced by heat pressing may be stacked and heat pressed again to laminate, or a pre-laminated flat film may be prepared and the film thickness may be adjusted by heat pressing. In addition, when a predetermined surface shape is to be formed on the film as a surface roughness adjustment, the predetermined surface shape may be applied to the surface of a roll or flat plate and then transferred. The surface shape may be a random uneven shape, and the surface roughness can be adjusted by changing the particle size or processing time (amount) during blasting.

[0079] 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.

[0080] 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.

[0081] <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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] <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.

[0094] 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.

[0095] From the viewpoints of mechanical strength and dimensional stability, the base film 6 is preferably a stretched film.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] An anchor coat layer may be provided on the surface of the base film 6 using a conventionally known anchor coat agent.

[0101] 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 laminate. Also, when the thickness of the base film is 50 μm or less, it is easy to maintain the processability of the laminate.

[0102] The adhesive layer 5 is a layer that bonds the base film 6 and the sealant film. In the packaging material 10, the auxiliary layer 4 of the sealant film and the base film 6 are bonded via the adhesive layer 5.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] The printed layer may represent characters, patterns, symbols, combinations thereof, and the like.

[0111] From the viewpoint of producing a packaging material with less environmental impact, the printed layer may be formed using ink derived from biomass.

[0112] The method for forming the printed layer is not particularly limited, and a conventionally known printing method such as gravure printing, offset printing, flexographic printing, etc., can be used. Among these, flexographic printing may be used from the viewpoint of environmental load.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] Each layer in the packaging material of the present embodiment may contain the additives described above.

[0117] 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.

[0118] The packaging material may include a sealant film having an auxiliary layer, a first base film laminated on the auxiliary layer via an adhesive layer, and a second base film having a printed layer laminated on the first base film via an adhesive layer. The packaging material may include a sealant film having an auxiliary layer and a first base film laminated on the auxiliary layer via an adhesive layer, a sealant film having an auxiliary layer, a first base film laminated on the auxiliary layer via an adhesive layer, and a gas barrier layer provided on the first base film, or a sealant film having an auxiliary layer, a first base film laminated on the auxiliary layer via an adhesive layer, and two or more functional layers such as a gas barrier layer or a printed layer provided on the first base film.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] <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

[0123] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0124] <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, 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.

[0125] (Recycled material 2) Recycled material 2 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, 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.

[0126] <Preparation of sealant film> Example 1 The recycled material 1 was put into the hopper extruding the recycled material-containing layer, and the LLDPE (Prime Polymer, product name "Evolu SP1540") with 6000 ppm of antiblocking agent (Prime Polymer, product name "EAZ-20") added by dry blending was put into the hopper extruding the sealant layer, and a 30 μm thick recycled material-containing layer and a 70 μm thick sealant layer were formed by co-extrusion molding using a single-screw multi-layer extruder 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, and the molten resin was cooled by an air knife and a cooling roll with a matte uneven shape (surface roughness Rz: 6 μm) provided by sandblasting processing.

[0127] Example 2 A sealant film was produced in the same manner as in Example 1, except that the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 43 rpm) to produce a recycled material-containing layer having a thickness of 80 μm and a sealant layer having a thickness of 20 μm.

[0128] Example 3 A sealant film was produced in the same manner as in Example 1, except that the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 48 rpm) to produce a recycled material-containing layer having a thickness of 90 μm and a sealant layer having a thickness of 10 μm.

[0129] Example 4 A sealant film was produced in the same manner as in Example 1, except that the molten resin was cooled under a pressure of 1.4 MPa using a nip roll (material: fluororesin) and a cooling roll that had been sandblasted to create a matte texture (surface roughness Rz: 6 μm), and the extrusion amount of each layer was adjusted to form a recycled material-containing layer with a thickness of 90 μm and a sealant layer with a thickness of 10 μm.

[0130] Example 5 A sealant film was produced in the same manner as in Example 1, except that recycled material 2 was added to a hopper for extruding the recycled material-containing layer, and the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 43 rpm) to produce a recycled material-containing layer having a thickness of 80 μm and a sealant layer having a thickness of 20 μm.

[0131] Example 6 A sealant film was produced in the same manner as in Example 5, except that the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 48 rpm) to produce a recycled material-containing layer having a thickness of 90 μm and a sealant layer having a thickness of 10 μm.

[0132] Example 7 A sealant film was produced in the same manner as in Example 5, except that the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 51 rpm) to produce a recycled material-containing layer having a thickness of 95 μm and a sealant layer having a thickness of 5 μm.

[0133] Example 8 A sealant film was produced in the same manner as in Example 5, except that the molten resin was cooled under a pressure of 1.4 MPa using a nip roll (material: fluororesin) and a cooling roll with a matte uneven surface (surface roughness Rz: 6 μm) created by sandblasting, and the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 48 rpm) to produce a recycled material-containing layer having a thickness of 90 μm and a sealant layer having a thickness of 10 μm.

[0134] Example 9 A sealant film was produced in the same manner as in Example 2, except that recycled material 1 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.

[0135] Example 10 A sealant film was produced in the same manner as in Example 2, except that a block polypropylene resin (bPP) (manufactured by Japan Polypropylene Corporation, product name "Novatec PP BC6DRF") to which 6,000 ppm of an antiblocking agent (manufactured by Prime Polymer, product name "EAZ-20") was added by dry blending was placed in the hopper for extruding the sealant layer.

[0136] Example 11 Only recycled material 1 was placed in the hopper extruding the recycled material-containing layer, LLDPE (Prime Polymer, product name "Evolue SP1540") with 6000 ppm of anti-blocking agent (Prime Polymer, product name "EAZ-20") added by dry blending was placed in the hopper extruding the sealant layer, and LLDPE (Prime Polymer, product name "Evolue SP1540") was placed in the hopper extruding the auxiliary layer, and a sealant film was produced by co-extrusion molding using a single-screw multi-layer extruder to form 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 43 rpm, and the narrowing of the flow path before the T-die was avoided as much as possible to create a mechanism that was less susceptible to elongational stress. The molten resin was cooled using an air knife and a cooling roll that had been sandblasted to give it a matte, uneven shape (surface roughness Rz: 6 μm) to produce a sealant film.

[0137] Comparative Example 1 A sealant film was prepared in the same manner as in Example 1, except that no antiblocking agent was added to the sealant layer.

[0138] Comparative Example 2 A sealant film was produced in the same manner as in Example 1, except that the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 51 rpm) to produce a recycled material-containing layer having a thickness of 95 μm and a sealant layer having a thickness of 5 μm.

[0139] Comparative Example 3 A sealant film was produced in the same manner as in Example 1, except that recycled material 2 was added to the hopper for extruding the recycled material-containing layer, no antiblocking agent was added to the sealant layer, and the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 43 rpm) to produce a recycled material-containing layer having a thickness of 80 μm and a sealant layer having a thickness of 20 μm.

[0140] Comparative Example 4 A sealant film was produced in the same manner as in Example 1, except that recycled material 2 was added to a hopper for extruding the recycled material-containing layer, and the extrusion rate of each layer was adjusted (the screw rotation speed when extruding the recycled material-containing layer was changed to 52 rpm) to produce a recycled material-containing layer having a thickness of 98 μm and a sealant layer having a thickness of 2 μm.

[0141] Comparative Example 5 A sealant film was prepared in the same manner as in Example 1, except that the amount of the antiblocking agent added was changed to 600 ppm.

[0142] <Surface roughness of sealant layer> The arithmetic surface roughness Ra of the surface of the sealant layer opposite to the recycled material-containing layer side was measured in accordance with JIS B 0601:2001 standard.

[0143] <Reliability evaluation when using sealant> Using a Tester Sangyo heat sealer (model number TP-701-B), the heat seal layers of the sealant film were overlapped and sealed with a sealing pressure of 0.2 MPa, a sealing time of 1 second, and a sealing width of 10 mm. The heat seal temperature was set to a temperature approximately 20°C above the melting point of the material of the heat seal layer (130°C for LLDPE, 180°C for PP). The heat seal area was then observed under a microscope and the seal was made 1mm thick. 2 The area ratio of air bubbles present in the observation area was calculated. When the area ratio of air bubbles was between 0% and less than 5%, it was marked as "◎", when it was between 5% and less than 10%, it was marked as "〇", when it was between 10% and less than 20%, it was marked as "△", and when it was 20% or more, it was marked as "×".

[0144] <Convex part of laminate layer> Using a Keyence laser microscope (VK-X200 / VK-X210), the maximum height H (the difference in height between the highest peak and the deepest valley in a given section) of the convex portion on the surface of the laminate layer opposite the recycled material-containing layer and the width W at half the maximum height H of the convex portion were measured, and the ratio to the maximum height H [W / H] was calculated.

[0145] <Film-forming property evaluation> The appearance of the film was visually observed from film formation to winding, and the film formability was evaluated according to the following criteria. "Good": No folds or wrinkles were observed during the process from film formation to winding, and no defects in appearance due to folds or wrinkles were observed in the film after winding. "X": Folds and wrinkles occurred during the process from film formation to winding, and poor appearance due to the folds and wrinkles was observed in the film after winding.

[0146] [Table 1]

[0147] [Table 2]

[0148] As shown in Tables 1 and 2, it was confirmed that the sealant films of Examples 1 to 11 had sufficient reliability and film-forming properties during heat sealing while containing recycled materials. Therefore, according to the present invention, material recycling of recycled materials containing two or more types of resins can be realized in sealant films and packaging materials. [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, 50... aggregate, 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 resin having the largest content ratio among the two or more resins contained in the recycled material is a polyethylene-based resin or a polypropylene-based resin; A sealant film, wherein the arithmetic surface roughness of the surface of the sealant layer opposite to the recycled material-containing layer is 0.5 μm or more and 5 μm or less.

2. The sealant film according to claim 1 , wherein the sealant layer has a thickness of 5 μm or more and 70 μm or less.

3. 2. The sealant film according to claim 1, wherein the maximum height H of the convex portions on the surface of the sealant layer is 0.5 μm or more and 10 μm or less, and the ratio [W / H] of the width W at half the maximum height H to the maximum height H of the convex portions having the maximum height H is 20 or less.

4. The sealant film according to claim 1 , further comprising an auxiliary layer laminated on the other main surface of the recycled material-containing layer.

5. The sealant film according to claim 4 , wherein the auxiliary layer contains a virgin resin of the same type as the resin having the highest content in the recycled material-containing layer.

6. 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 arithmetic surface roughness of the surface of the sealant layer opposite to the recycled material-containing layer is 0.5 μm or more and 5 μm or less. A sealant film, wherein the maximum height H of a convex portion on the surface of the sealant layer is 0.5 μm or more and 10 μm or less, and the ratio [W / H] of the width W at half the maximum height H to the maximum height H of the convex portion having the maximum height H is 20 or less.

7. The sealant film according to claim 6, wherein the sealant layer has a thickness of 5 μm or more and 70 μm or less.

8. The sealant film according to claim 6 , further comprising an auxiliary layer laminated on the other main surface of the recycled material-containing layer.

9. The sealant film according to claim 8 , wherein the auxiliary layer contains a virgin resin of the same type as the resin having the highest content in the recycled material-containing layer.

10. A packaging material comprising the sealant film according to any one of claims 1 to 9.

11. The packaging material according to claim 10, 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.

12. A packaging bag made from the packaging material according to claim 10.

13. A packaging bag made from the packaging material according to claim 11.

Images