Sealant film, packaging material and packaging bag

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 Art

[0002] Generally, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and capable of mass production, and are used in various applications. Their uses include, for example, packaging materials for packaging food products, pharmaceuticals, etc., drip bags, shopping bags, posters, tapes, optical films used in liquid crystal TVs, etc., protective films, window films adhered to windows, greenhouses, building materials, and so on, covering a wide range. Specific materials include, for example, thermoplastic resins such as polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, and thermosetting resins such as epoxy resins, polyurethanes, and polyimides.

[0003] An appropriate plastic material is selected according to the application, and furthermore, a plurality of them are stacked to form a laminate. There is also a way of using them by mixing a plurality of plastic materials in one layer to compensate for the disadvantages of a single material. In addition, there are also laminates provided with an aluminum foil for imparting light-shielding properties, a printed layer printed with a pattern with ink to give the product a design, and an adhesive layer for adhering incompatible plastic materials.

[0004] Recycling of plastic products is expected as a measure against current environmental problems, and various recycling methods are being studied. For example, for PET bottles, material recycling in which the collected products are washed, pulverized, and reused as raw materials, and chemical recycling in which they are monomerized, have been established. Further, Patent Document 1 below discloses a technique related to a sealant film containing recycled polyethylene resin. As the recycled polyethylene, it is described that those recovered from used polyethylene molded articles or waste materials during their production can be used, and those obtained through various processes such as pulverization, washing, filtration, and extraction can be used.

[0005] On the other hand, since plastic films are composed of various materials, it is difficult to reuse them as raw materials just by washing and pulverizing. Specifically, since an unspecified number of resins are mixed, it is impossible to obtain uniform melt physical properties (fluidity), making it difficult to mold. Even if it could be molded, the mechanical strength would be insufficient.

[0006] Due to such limitations, most plastic films are subjected to thermal recycling. However, due to their large circulation volume, it is also eagerly desired that plastic films be recycled as raw materials for film products such as packaging materials.

[0007] Previously, studies have been made on methods for reusing plastic films. For example, Patent Document 2 below proposes a method for efficiently extracting EVOH (ethylene-vinyl alcohol copolymer) from a multilayer resin molded body including an EVOH layer that functions as a gas barrier film.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in the above method, after dissolving EVOH in an EVOH extractant, EVOH is recovered by precipitation and sedimentation, which increases the labor and cost and is difficult to use easily.

[0010] Patent Document 1 proposes a sealant film in which an intermediate layer containing recycled polyethylene is provided between two virgin polyethylene layers made of virgin materials having no processing history, and deodorizing properties and concealment properties are evaluated. However, specific configurations and evaluations of sealant films using plastic films composed of various materials as recycled materials are not shown.

[0011] Therefore, when the inventors considered recycling plastic films as raw materials for sealant films, it was found that when different types of resins were mixed, resin components other than the resin with the maximum content ratio formed aggregates, which affected the smoothness and physical properties of the film. If the heat sealability and mechanical properties of the film are significantly impaired by such effects, it becomes difficult to increase the content rate of recycled plastic in packaging materials.

[0012] The present invention has been made in view of the above circumstances, and an object thereof is 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 a recycled material containing two or more types of resins.

Means for Solving the Problems

[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 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 lower transmission lightness than its surroundings when observed through transmission in the direction of viewing the sealant film in plan view, and the domain has a maximum area of 1000 μm 2 or less and a maximum aspect ratio of 10 or less, the sealant film. [2] The sealant film according to [1], wherein the recycled material-containing layer has an average value of lightness in HSV color space data of 200 or more and a standard deviation of lightness of 10 or less. [3] The sealant film according to [1] or [2], wherein the sealant layer contains a resin of the same type as the resin having the largest content ratio in the recycled material-containing layer. [4] The 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, and the auxiliary layer contains a resin of the same type as the resin having the largest content ratio 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 ratio among the two or more resins contained in the recycled material is a polyethylene-based resin or a polypropylene-based resin. [6] A packaging material comprising the sealant film according to any one of [1] to [5]. [7] The packaging material according to [6], wherein the content of the plastic material contained in the recycled material is 10% by mass or more based on the total amount of the plastic material in the packaging material. [8] A packaging bag formed from the packaging material according to [6] or [7]. [Effects 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 enable material recycling of a recycled material containing two or more resins while sufficiently having heat sealability and mechanical properties. [Brief Description of the Drawings]

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail. Note that FIGS. 1 to 6 are schematically shown figures, and the size, shape, etc. of each part are exaggerated as appropriate for easy understanding. In addition, 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 following in terms of the material, shape, structure, etc. of the components. The technical idea of the present invention can be variously modified 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 containing a recycled material containing two or more kinds of resins, 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 an 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 the recycled material contained in the recycled material-containing layer include, for example, post-consumer recycled (PCR) materials such as market-recovered bottles and packaging bags for beverages, detergents, and seasonings, food containers for bento and cup noodles, packaging bags for food and garbage bags, plastic finished products such as hangers, stationery, daily necessities, household appliances, and toys, and post-industrial recycled (PIR) materials such as defective products that do not become products discharged from factories, end materials generated during the process of making products, 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 pulverized as necessary. The material recycled material has the advantage of requiring less energy during recycling compared to a resin obtained by chemical recycling such as pyrolysis. Therefore, the larger 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) obtained by laminating a plurality of types of resin sheets, a packaging bag formed by bag-making the laminate, a laminate (packaging material) obtained by laminating the same type of resin sheets, or a packaging bag formed by bag-making the laminate, or a mixture thereof may be used. Examples of the packaging bag include, for example, refill pouches for toiletries.

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

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

[0025] Examples of the polyolefin resin 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, and polypropylene-based resins such as homopolypropylene (PP), block polypropylene, random polypropylene, and propylene-α-olefin copolymers.

[0026] Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polylactic acid, and the like.

[0027] Examples of the polyamide resin include nylon 6 and the like.

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

[0029] The first resin and the second resin may be the following combinations. (a) A thermoplastic resin and a thermosetting resin and its cured product (b) A hydrocarbon-based resin and a heteroatom-containing resin (c) A resin soluble in a predetermined solvent and a resin insoluble in the predetermined 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] Examples of the predetermined solvent in (c) include aromatic hydrocarbons and chlorinated hydrocarbons. Examples of the resin insoluble in the predetermined solvent include crosslinked resins and cured thermosetting resins.

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

[0033] The content of the first resin in the recycled material-containing layer may be 75 to 98% by mass, 75 to 95% by mass, or 80 to 90% by 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 with respect to 100 parts by mass of the first resin.

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

[0036] In the recycled material-containing layer, the resin having the largest content ratio and the resin having the largest content ratio in the recycled material may be the same. Such resins may be, for example, at least one polyethylene-based 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 virgin materials such as virgin resin. The virgin material may be blended so that the resin having the largest content ratio in the recycled material is the same as the resin having the largest content ratio in the recycled material-containing layer. As the virgin material, for example, the same materials as the above-described polyolefin resins can be used, and it may be at least one polyethylene-based 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 having a lower transmittance brightness than the surroundings when observed through transmission in the direction of the plan view of the sealant film (hereinafter, also referred to as "low transmittance brightness region"). The domain has a maximum area of 1000 μm 2 or less, and a maximum aspect ratio of 10 or less.

[0039] The maximum area and the maximum aspect ratio of the low transmittance brightness region are calculated by the following procedure. (i) Using a stereomicroscope system SZX16 (manufactured by Olympus Corporation, product name), 10 observation images in the plane direction of the sealant film (image size: 243 μm × 851 μm) are randomly obtained. (ii) Analyze the obtained 10 images using WinROOF2021 (manufactured by Mitani Corporation, product name). In the image analysis, by binarizing the low transmittance brightness region and the high transmittance brightness region around it, calculate the area, minimum diameter, and maximum diameter in each low transmittance brightness region. When binarizing, the visual shape and coloring range of the low transmittance brightness region can be matched by appropriately combining the following operations. (a) Emphasize the low transmittance brightness region by adjusting brightness and contrast (b) Adjust the threshold value to match the visible low transmittance brightness region and the coloring range (c) When there are places where adjacent low transmittance brightness regions are recognized as one region, or where perforated low transmittance brightness regions are recognized as multiple regions, perform splitting or integration processing as necessary.

[0040] Figure 2 is a schematic diagram for explaining the aspect ratio of the low transmittance brightness region. In Figure 2, a low transmittance brightness region 20 and a high transmittance brightness region 30 around it are shown. The aspect ratio of the low transmittance brightness region 20 is the ratio D L between the maximum diameter (major axis) D S and the minimum diameter (minor axis) D L / D S . Note that the minimum value of the aspect ratio is 1, and the shape of the low transmittance brightness region is not limited to the elliptical shape shown in Figure 2.

[0041] If the maximum area of the low transmittance brightness region specified by the above method exceeds 1000 μm 2 , that is, if there is a low transmittance brightness region with an area exceeding 1000 μm 2 , partial swelling derived from aggregates occurs on the film surface, resulting in a decrease in heat sealability and mechanical properties. Also, if the maximum aspect ratio of the low transmittance brightness region exceeds 10, that is, if there is a low transmittance brightness region with an aspect ratio exceeding 10, it combines with adjacent low transmittance brightness regions to form a pseudo-large-sized aggregate, bringing the same disadvantages as when there is a low transmittance brightness region with an area exceeding 1000 μm 2 .

[0042] From the perspective of compatibility with general manufacturing equipment and increasing the content ratio of recycled materials in the sealant film, the maximum area of the low transmittance region is 50 μm 2 or more, and may be 200 μm 2 or more, and may be 400 μm 2 or more. Also, the maximum aspect ratio of the low transmittance region may be 6 or more.

[0043] By the way, when using a film in the form of a product such as a pouch as a raw material for recycled materials, coloring components such as ink may be mixed in. In this case, if the colored portions are 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 printing layer or a white layer containing a white pigment to form a film. On the other hand, according to the sealant film according to the present embodiment, even when the recycled material contains a coloring component such as ink, by satisfying the above-described conditions for the maximum area and the maximum aspect ratio of the low transmittance region, appearance defects can be suppressed. Thereby, compared with the case of producing a sealant film only from virgin materials, it is possible to avoid the demerit that materials and processes for providing the above-described additional layers are required and the environmental load increases.

[0044] Also, from the same perspective as above, in the recycled material-containing layer, it is preferable that the low transmittance region is more dispersed over the entire surface than being localized, and the color uniformity is high.

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

[0046] The average value and the standard deviation of lightness in the HSV color space data of the recycled material-containing layer are calculated by the following procedure. (i) Cut out the sealant film into a size of ±200 mm width (400 mm width) from the center in the width direction and 250 mm in the flow direction. (ii) Cut out the sample and scan it 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 / Photo, Resolution: 600, Size: A3 (iii) Analyze the obtained image using image analysis software imageJ to calculate the average brightness value and standard deviation across the entire image. For the image analysis, convert the image saved in TIF format to HSB Stack, and obtain the average value and standard deviation calculated from the histogram of the V value (brightness) among the histogram analysis results in the HSV color space data. Note that the range of the V value is 0 to 255.

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

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

[0049] To reduce the maximum area and maximum aspect ratio of the low-transparency brightness region in the recycled material-containing layer, for example, the following adjustment means can be mentioned. (a) Reduce the content ratio of the recycled material in the recycled material-containing layer (b) Increase the content ratio of the above-mentioned first resin in the recycled material (c) When extruding the recycled material-containing layer, increase the screw rotation speed (d) When extruding the recycled material-containing layer, avoid narrowing the flow path as much as possible and make the mechanism such that elongation stress is less likely to be applied (e) Use the recycled material by repelletizing or mixing it with virgin resin using a twin-screw extruder to make a masterbatch

[0050] In order to increase the average value of lightness in the recycled material-containing layer, for example, methods such as reducing the maximum area of the low-transmission lightness region by the above-described adjustment means can be mentioned. Further, in order to reduce the standard deviation of lightness in the recycled material-containing layer, for example, methods such as selecting a resin to be mixed with the recycled material to increase fluidity so that the domains forming the low transparency region are not localized can be mentioned.

[0051] (Sealant layer) Examples of the resin for forming 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 can contain a resin of the same type as the resin having the largest content ratio in the recycled material-containing layer, and virgin resin may be blended so as to achieve this. For example, when the resin having the largest content ratio 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 ratio in the sealant layer is 95% by mass or more). Further, when the resin having the largest content ratio 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 ratio in the sealant layer is 95% by mass or more).

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

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

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

[0056] In this specification, the crystallinity of the polypropylene-based resin is determined from the ratio of the heat of fusion ΔHm obtained by integrating the endothermic peak during melting of the sample to the heat of fusion ΔH100 of a perfect crystal with a crystallinity of 100% obtained from theoretical calculations, as shown in the following formula. Crystallinity [%] = (ΔHm / ΔH100) × 100 Note that as the heat of fusion ΔH100 of the perfect crystal, the value described in the following reference can be adopted. For example, ΔH100 of polypropylene can be 207 J / g.) Reference: The Plastic Molding Processing Society: Plastic Materials in Molding Processing, 335 (2011), Morikita Publishing Co., Ltd.

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

[0058] In the recycle material-containing layer and the sealant layer, if necessary, compatibilizers, nucleating agents, reinforcing fillers, antioxidants, heat stabilizers, weathering agents, light stabilizers, plasticizers, ultraviolet absorbers, antistatic agents, flame retardants, flame retardant aids, slip agents, antiblocking agents, antifogging agents, lubricants, pigments, dyes, dispersants, copper corrosion inhibitors, neutralizing agents, antifoaming agents, weld strength improvers, natural oils, synthetic oils, waxes and other additives may be blended. The additives may be used singly or in combination of two or more.

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

[0060] Examples of the antioxidant include phenolic compounds, organic phosphite compounds, thioether compounds, and the like.

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

[0062] Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, benzoate compounds, and the like.

[0063] Examples of the antistatic agent include nonionic compounds, cationic compounds, anionic compounds, and the like.

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

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

[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. Thus, the sealant film of this embodiment may further include an auxiliary layer laminated on the main surface opposite to the side on which the sealant layer of the recycled material-containing layer is laminated.

[0067] When the auxiliary layer 4 is given a function as a laminate layer, it may have the same configuration as the sealant layer 3 described above. Further, the auxiliary layer 4 can contain a resin of the same type as the resin having the largest content ratio in the recycled material-containing layer 2. In this case, it becomes easy to improve the adhesion to another layer by higher laminate strength.

[0068] In the auxiliary layer 4, one or more of the above-described additives may be blended as necessary.

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

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

[0071] In the former method, the recycled material-containing film is obtained by melting the resin composition constituting the recycled material-containing layer with an injection molding machine or an extrusion molding machine (for example, a twin-screw extruder), and then forming it with a T-die through a feed block or a multi-manifold, or by an inflation method. As the recycled material, those obtained by collecting, washing, pulverizing various plastic waste materials and melt-molding them with an extruder and pelletizing them can be used. For extrusion lamination, an extrusion laminator or the like can be used.

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

[0073] The resin composition constituting the recycled material-containing layer may contain only the recycled material, or virgin resin and additives may be further blended to impart various desired properties such as viscosity adjustment and mechanical property reinforcement. Further, when mixing the recycled material and the virgin resin, it may be a dry blend in which the virgin resin and the recycled material are simultaneously charged into a hopper and formed into a film while melt-kneading, or a melt blend in which the virgin material and the recycled material are separately melt-kneaded by a twin-screw extruder to form a masterbatch.

[0074] From the viewpoint of reducing the maximum area and the maximum aspect ratio of the low transmission brightness region in the recycled material-containing layer, repelletizing using a twin-screw extruder, molding under high shear conditions, or blending an acid-modified polyolefin resin or the like as a compatibilizer may be performed.

[0075] Regarding the cooling method of the film, it can be used according to the molding machine. 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 into a cold water pan can be used. When imparting a surface uneven shape by shaping, a molten resin may be introduced into a contact portion where a nip roll processed with silicone rubber, NBR rubber, or a fluororesin, etc., and a cooling roll processed by cutting metal are applied with a pressure of 0.1 MPa or more, and cooled.

[0076] The sealant film may be subjected to a surface modification treatment to improve the suitability for subsequent processes. For example, in order to improve the printing suitability and the laminating suitability when laminating with another layer or a base film, a surface modification treatment can be performed on the surface to be laminated. Examples of the surface modification treatment include methods of expressing functional groups by oxidizing the film surface such as corona discharge treatment, plasma treatment, and flame treatment, and modification by wet processes such as coating an easy-adhesion layer.

[0077] Note that the method for manufacturing the sealant film is not limited to the method described above, and an inline or offline stretching treatment may be performed on the sealant film formed by a film forming machine. In addition, adding necessary processes and additives as appropriate is not restricted.

[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 an embodiment of the laminate of this embodiment. In the laminate 10a shown in FIG. 4, a gas barrier layer 12 is further provided on the side opposite to the recycled material-containing layer 2 of the auxiliary layer 4 in the sealant film 1b shown in FIG. 3. The laminate 10a can have improved gas barrier properties (for example, oxygen barrier properties and water vapor barrier properties, etc.). The gas barrier layer may have a single-layer structure or a laminated structure.

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

[0080] The vapor deposition layer may have a single-layer structure or a laminated structure. Examples of the vapor deposition layer include vapor deposition 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 vapor deposition layer can be formed using a conventionally known method. The forming method can be appropriately selected according to the vapor deposition material, etc., such as physical vapor deposition methods (Physical Vapor Deposition method, PVD method) such as vacuum vapor deposition method, sputtering method, and ion plating method, and chemical vapor deposition methods (Chemical Vapor Deposition method, CVD method) such as plasma chemical vapor deposition method, thermal chemical vapor deposition method, and photo chemical vapor deposition method.

[0082] When the vapor deposition layer is an aluminum vapor deposition film, its OD value may be 2 or more and 3.5 or less from the viewpoints of the 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 vapor 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 the barrier property. From the viewpoint of obtaining the above effects more sufficiently, the O / Si ratio of the inorganic oxide layer may be 1.5 or more and 2.0 or less, or may be 1.6 or more and 1.8 or less.

[0084] The O / Si ratio of the above inorganic oxide layer can be determined by X-ray photoelectron spectroscopy (XPS). For example, the measuring device can be an X-ray photoelectron spectrometer (manufactured by JEOL Ltd., trade name: JPS-90MXV), the X-ray source can use non-monochromatized MgKα (1253.6 eV), and it can be measured with an X-ray output of 100 W (10 kV - 10 mA). For quantitative analysis to obtain 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 vapor 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 vapor deposition layer is 1 nm or more, the oxygen barrier property and water vapor barrier property are likely to be obtained. When the thickness of the vapor deposition layer is 150 nm or less, it is easy to prevent the generation of cracks in the vapor 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 configuration as the above-described sealant layer 3. When the auxiliary layer 4 contains a polyolefin resin, the polyolefin resin preferably has higher crystallinity from the viewpoints of printability, vapor deposition suitability, strength, and heat resistance. The polyolefin resin may be a virgin resin.

[0087] When the above 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 drawability. When the above polyolefin resin is polypropylene, the crystallinity by the heat of fusion using a differential scanning calorimeter (DSC) may be 40% or more, may be 45% or more from the viewpoints of printability, strength, and heat resistance, and may be 60% or less, may be 55% or less from the viewpoint of impact resistance.

[0088] The content ratio of the non-material recycled resin (such as virgin resin) in the auxiliary layer 4 provided with the gas barrier layer can be higher than the content ratio of the non-material recycled resin in the recycled material-containing layer. In this case, it is possible to smooth the partial swelling derived from the aggregates on the surface of the recycled material-containing layer, and it is possible to improve the mechanical properties and gas barrier properties of the laminate.

[0089] The thickness of the auxiliary layer 4 provided with the gas barrier layer may be 20 μm or more, may be 40 μm or more, may be 80 μm or more from the viewpoints of gas barrier properties and adhesion, and may be 150 μm or less, may be 120 μm or less, may be 100 μm or less from the viewpoint of suppressing 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 an embodiment of the packaging material. The packaging material 100 shown in FIG. 5 includes a sealant film 1b having an auxiliary layer 4, and a base film 6 laminated on 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 plastic films, paper, non-woven fabrics, etc. can be used. Examples of the constituent materials of the plastic film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, polyamides such as polystyrene and 6-nylon, polycarbonate, polyacrylonitrile, polyimide, and the like.

[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 as the resin having the largest content ratio in the sealant film (also referred to as "the same resin"), the base film 6 can be made into a single material as the entire packaging material, and the recyclability of the packaging material is improved. 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 having the largest content ratio in the recycle 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 can be referred to as a packaging material made of a single material (monomaterial). From the viewpoint of further improving the recyclability, the content of the same resin in the packaging material may be 92.5% by mass or more, or 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 20% or less. In this specification, the haze value of the film means a value measured in accordance with JIS K 7105.

[0096] The base film 6 may be surface-treated. In this case, the adhesion to an adjacent layer can be improved. The method of 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, glow discharge treatment, and chemical treatments such as oxidation treatment using chemical agents.

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

[0099] The adhesive layer 5 is a layer that adheres 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 adhered 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 two-component curable urethane adhesives, polyester urethane adhesives, polyether urethane adhesives, acrylic adhesives, polyester adhesives, polyamide adhesives, epoxy adhesives, and the like.

[0101] When the packaging material is used for a retort pouch, a two-component curable 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) It does not contain 3-glycidoxypropyltrimethoxysilane (GPTMS). (2) It contains biomass materials. (3) It does not contain a solvent.

[0103] From the viewpoint of suppressing coloring of recycled resin and the like and the generation of odor due to heat treatment after recycling, the adhesive layer 5 may not contain chlorine.

[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 force 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, it 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 below the above upper limit value, the ratio of the single material in the packaging material can be increased.

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

[0106] The printing layer may be formed on the surface of the base film on the side where the sealant film is provided. In this case, it is possible to prevent the printing layer from coming into contact with the outside air and prevent deterioration over time.

[0107] The printing layer may represent characters, patterns, symbols, and combinations thereof.

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

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

[0110] The gas barrier layer can be provided on the base film and may have the same configuration as the above-mentioned gas barrier layer 12.

[0111] Alternatively, a gas barrier layer may be provided by laminating a laminated film of a metal foil and a plastic film, or a vapor deposition film provided with a vapor deposition layer (vapor deposition film) made of the above-described 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, and polyimide.

[0112] FIG. 6 is a schematic cross-sectional view showing another embodiment of the 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 recycle material-containing layer 2, and an auxiliary layer 4 and a gas barrier layer 12 are laminated in this order, and a base material film 6 having a printing layer 7 adhered via an adhesive layer 5 on the gas barrier layer 12 side of the laminate. In the packaging material 102, as described above, the printing layer 7 is formed on the surface of the base material 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 above-described additives.

[0114] The packaging material of the present embodiment can be variously modified other than the above-described configuration, and may have the following configuration. (a) The sealant film / adhesive layer / gas barrier film / adhesive layer / base material film of the present embodiment (b) The sealant film / adhesive layer / gas barrier film of the present embodiment (c) The sealant film / gas barrier layer (for example, vapor deposition layer) / adhesive layer / base material film of the present embodiment As the above-described gas barrier film, the base film provided with the gas barrier layer, the laminated film of a metal foil and a plastic film, and the vapor deposition film described above may be used, and a metal foil such as an aluminum foil, and a film such as an ethylene-vinyl alcohol copolymer, a polyamide resin, a polyvinylidene chloride resin, or a polyacrylonitrile resin may also be used.

[0115] Further, 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 printing layer laminated on the first base film via an adhesive layer.

[0116] From the viewpoint of material recycling, the content of the plastic material contained in the recycling material 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 the plastic material in the packaging material. When the packaging material of the present embodiment is a laminated packaging material, materials other than plastic (for example, adhesives, printing inks, aluminum foils, etc.) may be excluded from the weight calculation.

[0117] Examples of the plastic material (so-called recycled plastic) contained in the recycling material include the resins contained in the recycling material included in the recycling material-containing layer according to the above-described present embodiment. Among the recycled plastics, pre-consumer materials may be calculated by multiplying the weight by 1 / 2.

[0118] The packaging material of the present embodiment can be used for a standing pouch, a three-side bag, a gusseted bag, a gusset bag, a pouch with a spout, a pouch with a beak, etc.

[0119] <Packaging bag> The packaging bag of the present embodiment is formed from the packaging material of the present embodiment described above. The bag-making style of the packaging bag is not particularly limited, and the packaging bag may be a standing pouch, a three-side bag, a gusseted bag, a gusset bag, a pouch with a spout, a pouch with a beak, etc.

Examples

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

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

[0122] (Recycled Material 2) A PP film (manufactured by Toray Film Processing Co., Ltd., product name "Trephan 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 printing layer, and a Ny film (manufactured by Toyobo Co., Ltd., product name "Hardene Film N1100", film thickness 15 μm) were laminated in this order, and the film was compressed and cut into granules to obtain Recycled Material 2. The adhesive layer was formed in the same manner as Recycled Material 1.

[0123] (Recycled Material 3) An LLDPE film (manufactured by Mitsui Chemicals Toagosei Co., Ltd., product name "TUX FC-S", film thickness 100 μm), an adhesive layer, an HDPE film (manufactured by Tamapoly Co., Ltd., product name "HF31", film thickness 35 μm), an adhesive layer, a printing layer, and an HDPE film (manufactured by Tamapoly Co., Ltd., product name "HF31", film thickness 35 μm) were laminated in this order, and the film was compressed, cut, and molded into granules to obtain a recycled material 3. The adhesive layer was formed in the same manner as the recycled material 1.

[0124] <Production of Sealant Film> (Example 1) Recycled material 1 and LLDPE (manufactured by Prime Polymer Co., Ltd., product name "Evolue SP2040") were charged into the hopper for extruding the recycled material-containing layer so that the weight ratio was 1:1, and LLDPE (manufactured by Prime Polymer Co., Ltd., product name "Evolue SP2040") was charged into the hopper for extruding the sealant layer. Using a single-screw multi-layer extruder, a recycled material-containing layer with a thickness of 80 μm and a sealant layer with a thickness of 20 μm were formed into a film to produce a sealant film. The screw rotation speed when extruding the recycled material-containing layer was set to 16 rpm, and narrowing of the flow path before the T-die was avoided as much as possible to form a mechanism where elongation stress was less likely to be applied.

[0125] (Example 2) A sealant film was produced in the same manner as in Example 1, except that only recycled material 1 was charged into 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 charged into the hopper for extruding the recycled material-containing layer instead of recycled material 1, and block polypropylene resin (bPP) (manufactured by Nippon Polypropylene Co., Ltd., product name "Novatec PP BC6DRF") was used in the hopper for 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 into the hopper for extruding the recycled material-containing layer instead of recycled material 1.

[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 Co., Ltd., product name "Evolue SP2040") were charged into the hopper for extruding the recycled material-containing layer so that the weight ratio was 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 into the hopper for extruding the recycled material-containing layer instead of recycled material 1.

[0130] (Example 7) Only recycled material 1 was charged into the hopper for extruding the recycled material-containing layer, LLDPE (manufactured by Prime Polymer Co., Ltd., product name "Evolue SP2040") was charged into the hopper for extruding the sealant layer, and LLDPE (manufactured by Prime Polymer Co., Ltd., product name "Evolue SP2040") was charged into the hopper for extruding the auxiliary layer. By coextrusion molding using a single-screw multi-layer extruder, an auxiliary layer with a thickness of 20 μm, a recycled material-containing layer with a thickness of 80 μm, and a sealant layer with a thickness of 20 μm were formed into a film in this order to produce a sealant film. The screw rotation speed when extruding the recycled material-containing layer was set to 16 rpm, and the narrowing of the flow path in front of the T-die was avoided as much as possible to make a mechanism in which elongation stress is less likely to be applied.

[0131] (Reference Example 1) A commercially available PE sealant film (manufactured by Tamapoli 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 in front of the T-die to make a mechanism in which elongation stress is applied 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 the screw rotation speed was reduced to 10 rpm when extruding the recycled material-containing layer, and an orifice was inserted in front of the T-die to provide a mechanism for applying elongation stress.

[0135] (Comparative Example 4) A sealant film was produced in the same manner as in Example 4, except that the screw rotation speed was reduced to 10 rpm when extruding the recycled material-containing layer, and an orifice was inserted in front of the T-die to provide a mechanism for applying elongation 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 in front of the T-die to provide a mechanism for applying elongation stress when extruding the recycled material-containing layer.

[0138] (Analysis of the recycled material-containing layer) (Maximum area and maximum aspect ratio of the low transmission brightness region) The maximum area and maximum aspect ratio of the low transmission brightness region in the recycled material-containing layer were calculated by the following procedure. (i) Using a stereomicroscope system SZX16 (manufactured by Olympus Corporation, product name), 10 observation images (image size: 243 μm × 851 μm) in the plane direction of the sealant film were randomly obtained. (ii) The obtained 10 images were subjected to image analysis using WinROOF2021 (manufactured by Mitani Corporation, product name). In the image analysis, the low transmittance region and the high transmittance region around it were binarized. When binarizing, the following operations were appropriately performed to match the visual shape and coloring range of the low transmittance region. (a) Emphasize the low transmittance region by adjusting brightness and contrast (b) Adjust the threshold to match the visible low transmittance region and the coloring range (c) When there are places where adjacent low transmittance regions are recognized as one region, or where perforated low transmittance regions are recognized as multiple regions, perform splitting or integration processing as necessary

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

[0140] (Average value and standard deviation of lightness) The average value and standard deviation of lightness in the HSV color space data of the recycled material-containing layer were calculated by the following procedure. (i) The sealant film was cut out into a size of ±200 mm width (400 mm width) from the center in the width direction and 250 mm in the flow direction. (ii) The cut-out 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 / photo, Resolution: 600, Size: A3 (iii) The obtained image was subjected to image analysis using image analysis software imageJ to calculate the average value and standard deviation of lightness over the entire image. Note that for the image analysis, the image saved in TIF format was converted to an HSB Stack, and the average value and standard deviation calculated from the histogram of the V value (lightness) among the histogram analysis results in the HSV color space data were obtained. Note that the range of the V value is 0 to 255.

[0141] (Evaluation of the sealant film) (Heat seal strength) The sealant film layer sides of two sealant films were overlapped, heat-sealed with a width of 20 mm leaving 10 mm at the ends, and both long-side ends were cut off by 5 mm each to produce a test piece with a width of 10 mm. The heat seal temperature was changed by 10 °C in the range of 120 to 180 °C. For each test piece, using a tensile universal testing machine RTG-1310 (manufactured by A&D Company, Ltd., product name), the 10 mm portion that was not sealed was attached to the upper and lower chucks and pulled at 100 mm / min. At this time, regardless of the heat seal temperature, when the strength equal to or higher than that of a commercially available sealant film (Reference Example 1) was obtained, it was evaluated as "◎", when it was less than the strength of the commercially available sealant film but the test piece broke, it was evaluated as "〇", and when interfacial peeling or cohesive failure occurred, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0142] (Breaking strength) Test pieces were cut out from the sealant film in a size of 15 mm × 25 mm such that the film-forming flow direction became the long side. The test pieces were installed in a tensile universal testing machine RTG-1310 (manufactured by A&D Company, Ltd., product name) so that the distance between the chucks was 20 mm and pulled at 100 mm / sec. At this time, if the elongation equal to or higher than that of a commercially available sealant film (Reference Example 1) was shown, it was evaluated as "〇", and if it was less than that of the commercially available sealant film, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0143] (Appearance 1) On the surface of the sealant film opposite to the sealant layer, a laminated structure of an adhesive layer, a PET film (manufactured by Toyobo Co., Ltd., E5202, film thickness 12 μm), an adhesive layer, a printing layer, and a Ny film (manufactured by Toyobo Co., Ltd., product name "Harden Film N1100", film thickness 15 μm) was provided to obtain a laminate. On the other hand, a comparative laminate was obtained by providing the same laminated structure as above on a commercially available sealant film (Reference Example 1). When the laminate had the same appearance (color and taste) as the comparative laminate, it was evaluated as "〇", and when it seemed to have a different appearance (color and taste) from the comparative laminate, it was evaluated as "×". The results are shown in Tables 1 and 2.

[0144] (Appearance 2) 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 printing layer, and a Ny film (manufactured by Toyobo Co., Ltd., product name "Harden Film N1100", film thickness 15 μm) were provided on the surface of the sealant film opposite to the sealant layer to obtain a laminate. On the other hand, a comparative laminate was obtained by providing the same laminate structure as above on a commercially available sealant film (Reference Example 1). When the laminate had the same appearance (surface smoothness (absence of unevenness)) as the comparative laminate, it was evaluated as "◎", when the appearance (surface smoothness (absence of unevenness)) was inferior to that of the comparative laminate but there was no practical problem, it was evaluated as "〇", and when there was a practical problem, 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 elongation at break equal to or higher than those of the commercially available sealant film, and it was confirmed that they sufficiently had heat sealability and mechanical properties while containing a recycled material.

[0148] Also, according to the sealant films of Examples 1 to 7, although the recycled material contained the printing layer, since a laminate having an appearance equal to or higher than that of the laminate produced using the commercially available sealant film could be obtained, materials and processes for providing an additional layer for concealing poor appearance could be omitted. Thus, it was also confirmed that according to the present invention, it is possible to realize a packaging material that suppresses costs and environmental load while using a recycled material.

Explanation of Reference Numerals

[0149] 1a, 1b... sealant film, 2... recycled material-containing layer, 3... sealant layer, 4... auxiliary layer, 5... adhesive layer, 6... base film, 7... printing layer, 10a... laminate, 12... gas barrier layer, 20... low transmittance region (aggregate), 30... high transmittance 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 a maximum aspect ratio of 10 or less.

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. The sealant film according to claim 1 , wherein the sealant layer contains a resin of the same type as the resin having the highest content in the recycled material-containing layer.

4. 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.

5. 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.

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

7. 7. The packaging material according to claim 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 according to claim 6.

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

Images