Laminate, sealant film using same, packaging material and packaging bag, and method for producing laminate

Abstract

To provide a laminate having a homogeneous and sufficient transparent feeling while containing a recycled material.SOLUTION: The laminate includes a first layer formed of a first resin composition, a second layer formed of a second resin composition, and an intermediate layer formed of a third resin composition provided between the first layer and the second layer. Among the first plastic composition, the second plastic composition, and the third plastic composition, at least the third plastic composition contains a recycled material, the first plastic composition in the case of containing a recycled material has a YI value of 9mm - 1 or less per unit thickness when formed into a film, the second plastic composition in the case of containing a recycled material has a YI value of 9mm - 1 or less per unit thickness when formed into a film, A ratio of the melt flow rate of the first resin composition to the melt flow rate of the third resin composition and a ratio of the melt flow rate of the second resin composition to the melt flow rate of the third resin composition are 0.3 to 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminate, a sealant film, a packaging material and a packaging bag using the same, and a method for manufacturing the laminate. [Background technology]

[0002] In general, plastic films have properties such as being lightweight, chemically stable, easy to process, flexible and strong, and capable of mass production, and are therefore used in a wide variety of applications. Their applications are diverse, including packaging materials for food products, pharmaceuticals, etc., intravenous drip packs, shopping bags, posters, tapes, optical films used in LCD televisions, etc., protective films, window films attached to windows, greenhouses, building materials, etc. Specific materials include thermoplastic resins such as polyethylene, polypropylene, polystyrene, polymethyl methacrylate, 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 film's intended use, and multiple types of film are sometimes layered to form laminates. Mixing multiple plastic materials into a single layer can also be used to compensate for the shortcomings of a single material. Other examples include laminates with aluminum foil to provide light blocking properties, printed layers with ink designs to enhance product design, and adhesive layers to bond incompatible plastic materials.

[0004] Recycling plastic products is expected to be a key part of addressing recent environmental issues, and various recycling methods are being considered. Established recycling methods include material recycling, in which collected PET bottles are washed, crushed, and reused as raw materials, and chemical recycling, in which plastic is converted into monomers.

[0005] Patent Document 1 listed below discloses a technology relating to a sealant film containing recycled polyethylene resin, and describes that recycled polyethylene can be recovered from used polyethylene molded bodies or waste materials from their production, and obtained through various processes such as crushing, washing, filtering, and extraction. [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] From the viewpoints of safety and sales promotion, packaging materials are sometimes required to be easily visible, allowing the state of the contents and product information to be easily recognized. In such cases, the plastic film constituting the packaging material is required to have excellent transparency. When using recycled material in the production of such plastic films, if the film has a single-layer structure, the film surface tends to become rough depending on the degree of deterioration of the recycled material, and the transparency tends to be impaired due to increased haze. Therefore, when the use of recycled material in the production of films with a multilayer structure was investigated, it was found that uniform transparency may be impaired due to disturbances at the interfaces between the layers.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a laminate that contains recycled materials but is homogeneous and has sufficient transparency, a sealant film, a packaging material and a packaging bag using the same, and a method for manufacturing the laminate. [Means for solving the problem]

[0009] In order to solve the above problems, the present inventors have conducted extensive research and have found that, in the production of a laminate, by carrying out material recycling using as indicators the melt flow rate (MFR) of the resin composition forming adjacent layers and the yellow index (YI) value per unit film thickness of the outermost layer in the laminate, a laminate in which the resin compositions forming adjacent layers satisfy a specific MFR ratio and the YI value of the outermost layer in the laminate is within a specific range will have homogeneous and sufficient transparency.

[0010] One aspect of the present disclosure relates to the following [1] to

[11] .

[0011] [1] A film comprising a first layer formed from a first resin composition, a second layer formed from a second resin composition, and an intermediate layer formed from a third resin composition provided between the first layer and the second layer, wherein at least the third resin composition among the first resin composition, the second resin composition, and the third resin composition contains a recycled material, and the first resin composition when containing a recycled material has a YI value per unit film thickness of 9 mm or more when formed into a film. -1 The second resin composition containing recycled materials has a YI value per unit film thickness of 9 mm or less when formed into a film. -1 or less, wherein the ratio [MFR1 / MFR3] of the melt flow rate MFR1 (g / 10 min) of the first resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12, and the ratio [MFR2 / MFR3] of the melt flow rate MFR2 (g / 10 min) of the second resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12. [2] The laminate according to [1], wherein the first resin composition and the second resin composition contain recycled materials. [3] The laminate according to [1] or [2], wherein the recycled material is a polyolefin resin. [4] The laminate according to any one of [1] to [3], wherein the thickness of the first layer and the second layer is 5 μm or more, and the thickness of the entire laminate is 150 μm or less. [5] The laminate according to any one of [1] to [4], wherein the recycled material is a post-industrial recycled material. [6] YI value per unit thickness of the entire laminate is 0 to 9 mm -1 The laminate according to any one of [1] to [5], wherein [7] The laminate according to any one of [1] to [6], wherein the first resin composition, the second resin composition, and the third resin composition contain the same type of resin. [8] A sealant film comprising the laminate according to any one of [1] to [7]. [9] A packaging material comprising the laminate according to any one of [1] to [7].

[10] A packaging material obtained by making a bag from the packaging material described in [9].

[11] A method for producing a laminate comprising extrusion laminating or co-extrusion molding a first resin composition forming a first layer, a second resin composition forming a second layer, and a third resin composition forming an intermediate layer to obtain a laminate in which the first layer, the intermediate layer, and the second layer are laminated in this order, the method comprising recycling a part of the laminate as a recycled material into at least the third resin composition out of the first resin composition, the second resin composition, and the third resin composition, the method comprising recycling a part of the laminate as a recycled material into at least the third resin composition, the recycled material having a YI value per unit film thickness of 9 mm when formed into a film. -1 or less, recycling the recycled material into at least one of the first resin composition and the second resin composition, wherein in the step, a ratio [MFR1 / MFR3] of a melt flow rate MFR1 (g / 10 min) of the first resin composition to a melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12, and a ratio [MFR2 / MFR3] of a melt flow rate MFR2 (g / 10 min) of the second resin composition to a melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a laminate that contains recycled materials but is homogeneous and has sufficient transparency, a sealant film, a packaging material and a packaging bag using the same, and a method for manufacturing the laminate. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating one embodiment of a laminate according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating one embodiment of a packaging material according to the present disclosure. [Figure 3] FIG. 3 is a diagram for explaining an evaluation test of the interface disturbance. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. Note that FIGS. 1 and 2 are schematic diagrams, and the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, the embodiments shown below are merely examples of configurations for embodying the technical idea of ​​the present disclosure, and the technical idea of ​​the present disclosure is not limited to the following in terms of component materials, shapes, structures, etc. The technical idea of ​​the present disclosure can be modified in various ways within the technical scope defined by the claims.

[0015] [Laminate] The laminate of this embodiment includes a first layer formed from a first resin composition, a second layer formed from a second resin composition, and an intermediate layer formed from a third resin composition provided between the first and second layers. The laminate of this embodiment includes the first layer and the second layer on the outermost surfaces.

[0016] Fig. 1 is a cross-sectional view schematically illustrating one embodiment of a laminate according to the present disclosure. The laminate 1 shown in Fig. 1 has a structure in which a first layer 11, an intermediate layer 12, and a second layer 13 are laminated in this order.

[0017] From the viewpoint of material recycling of plastic films, the laminate of this embodiment may be used for a laminate (packaging material) made by bonding together resin sheets of the same type, or a packaging bag made from such a laminate, or a mixture of these.

[0018] <Resin composition> The first, second, and third resin compositions contain a resin. The resin contained in the resin composition may be a thermoplastic resin or other resin that has appropriate flexibility and good processability, for example, suitability for processing using an extruder. Examples of such resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and polypropylenes having homopolymers, random copolymers, and block copolymers; ethylene-vinyl acetate copolymers obtained by copolymerizing olefins such as low-density polyethylene (LDPE) with vinyl acetate; and ethylene-methyl acrylate copolymers (EMA), ethylene-ethyl acrylate copolymers (EEA), ethylene-butyl acrylate copolymers (EBA), and ethylene-methacrylic acid copolymers (EMAA), which are obtained by modifying the side chains of olefins. These resins may be used alone or in combination.

[0019] Of the first, second, and third resin compositions, at least the third resin composition contains recycled materials. Furthermore, from the viewpoint of further reducing the environmental load, at least one of the first and second resin compositions may contain recycled materials, or both the first and second resin compositions may contain recycled materials.

[0020] Examples of recycled materials that can be used include post-consumer recycled (PCR) materials, such as recycled bottles and packaging bags for beverages, detergents, and seasonings, food containers for lunch boxes and instant noodles, packaging bags for food and garbage bags, and 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 cannot be used as products discharged from factories, offcuts generated during the manufacturing process, and plastic products used for transportation and packaging. Compared to PCR, PIR has less debris adhesion, and since specific plastic products are collected, the plastic material is uniform, resulting in consistent quality of the recycled material.

[0021] When using PCR materials, there is a possibility that the surface may be contaminated at the time of use, so it may be possible to clean it in advance with a surfactant or alkali.

[0022] The recycled material contains a resin. Hereinafter, the resin contained in the recycled material is also referred to as a recycled resin. The recycled resin is preferably a single material. When the recycled resin is made into a single material, the following methods can be mentioned. (a) A method for recycling materials consisting of a single material discarded during the manufacturing process of packaging bags. (b) Material recycling of recycled packaging bags made of a single material (c) A method of purifying and using a single resin from a material containing multiple resins (d) Method using chemically recycled resin

[0023] Method (a) is PIR and material recycling, and since the recycled material is a single material, it maintains the physical properties of the laminate while emitting less carbon dioxide during the recycling process.

[0024] Method (b) is PCR and material recycling, and allows the recovery of materials composed of a single material from the market.

[0025] Method (c) is PCR and material recycling, and compared to method (b), it requires an additional purification process, but it allows more packaging bags to be treated as recycled material.

[0026] Method (d) is chemical recycling, which produces more carbon dioxide emissions than material recycling, but the quality is high and the recycled material is equivalent to virgin resin.

[0027] Although it is preferable to use a recycled material made of a single material using the above method, recycled materials containing two or more resins may also be used. In this case, it is preferable that the mass ratio of the resin with the largest mass ratio in each recycled material is 80 mass% or more based on the total mass of the recycled material.

[0028] Examples of recycled resins include thermoplastic resins, thermosetting resins, and cured products thereof (including crosslinked products).

[0029] Examples of thermoplastic resins include polyolefin resins, acrylic resins, polycarbonate resins, polyester resins, polyamide resins, etc. Examples of thermosetting resins include epoxy resins, polyurethane resins, polyimide resins, etc.

[0030] Examples of polyolefin resins include polyethylene 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 resins such as homopolypropylene (PP), block polypropylene, random polypropylene, and propylene-α-olefin copolymers. Two or more types of polyolefin resins may be contained.

[0031] Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polylactic acid.

[0032] An example of the polyamide resin is nylon 6.

[0033] From the viewpoint of adhesion between the first layer and the intermediate layer, and between the second layer and the intermediate layer, the recycled material is preferably a polyolefin resin.

[0034] The first, second, and third resin compositions may each contain a virgin material such as a virgin resin, or may contain a recycled material and a virgin material. When a virgin material is used, a higher quality laminate can be provided, and when a recycled material is used, the mass ratio of the recycled material in the entire laminate increases, and a laminate with a reduced environmental impact can be provided.

[0035] As the virgin material, for example, the same polyolefin-based resin as described above 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), high-density polyethylene (HDPE), and ethylene-α-olefin copolymer, or at least one polypropylene-based resin selected from the group consisting of homopolypropylene (PP), block polypropylene, random polypropylene, and propylene-α-olefin copolymer.

[0036] The content of recycled material in each of the first, second and third resin compositions may be 13% by mass or more, 33% by mass or more, 50% by mass or more, 80% by mass or more, or 100% by mass, based on the total mass of each of the first, second and third resin compositions, from the viewpoint of making it easier to make the content of recycled material in the laminate (equivalent to plastic material) 10% by mass or more and improving recyclability.

[0037] The content of recycled material in the entire laminate may be 10% by mass or more, 13% by mass or more, 33% by mass or more, 50% by mass or more, 80% by mass or more, or 100% by mass, based on the total mass of the plastic material in the packaging material, from the viewpoint of improving recyclability by making it easier to achieve a recycled material content (equivalent to plastic material) of 10% by mass or more, based on the total mass of the laminate.

[0038] In the laminate of this embodiment, the first resin composition containing recycled material has a YI value per unit thickness of 9 mm when formed into a film. -1 The second resin composition containing recycled materials has a YI value of 9 mm or less per unit film thickness when formed into a film. -1 This makes it possible to prevent the roughness of the outermost surface of the laminate from increasing, even when the outermost layer of the laminate contains recycled material, and to realize a laminate having sufficient transparency. Note that, when the first resin composition and the second resin composition are formed into a film without containing recycled material, the YI value per unit film thickness is not particularly limited, but is preferably low from the viewpoint of obtaining a laminate having homogeneity and sufficient transparency, and is, for example, 9 mm -1 It may be the following:

[0039] The YI value in this disclosure refers to the YI value measured under conditions of a D65 light source and a 2° field of view in accordance with JIS K7373: 2006. The YI value can be measured, for example, under conditions of a D65 light source and a 2° field of view using a spectral color haze meter COH7700 manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7373: 2006.

[0040] The first resin composition containing recycled materials and the second resin composition containing recycled materials each have a YI value per unit film thickness of 0 mm when formed into a film. -1 More than 5.5mm -1 It may be more than 9mm -1 Less than or equal to 8.5mm -1 It may be the following:

[0041] The method for forming a film from the resin composition is not particularly limited, and various methods can be appropriately selected, for example, heat pressing, extrusion molding, casting molding, calendar molding, etc. The formed film may be subjected to various stretching processes such as uniaxial stretching, sequential biaxial stretching, simultaneous biaxial stretching, and multistage stretching.

[0042] The recycled material is preferably a material obtained by material recycling of post-industrial recycled material, since it is possible to stably obtain a recycled material of a single material. The recycled material may be, for example, a material recycled material of factory offcuts.

[0043] In the laminate of this embodiment, the ratio [MFR1 / MFR3] of the melt flow rate MFR1 (g / 10 min) of the first resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12, and the ratio [MFR2 / MFR3] of the melt flow rate MFR2 (g / 10 min) of the second resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12. This makes it possible to prevent disruption of the interface between the first layer and the intermediate layer and the interface between the second layer and the intermediate layer, and makes it possible to provide a laminate that is homogeneous and has sufficient transparency despite containing recycled materials.

[0044] The melt flow rate (MFR) in the present disclosure is an MFR measured at a temperature of 190°C and a load of 2.16 kg in accordance with JIS K 7210. The MFR can be measured using, for example, a melt indexer manufactured by Toyo Seiki Seisakusho, Ltd.

[0045] In order to further suppress disturbance of the interface between the first layer and the intermediate layer and the interface between the second layer and the intermediate layer, the ratio [MFR1 / MFR3] of the melt flow rate MFR1 (g / 10 min) of the first resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition and the ratio [MFR2 / MFR3] of the melt flow rate MFR2 (g / 10 min) of the second resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition may be 0.3 or more or 0.67 or more, and may be 11.5 or less, 5.0 or less, or 3.5 or less, respectively.

[0046] From the viewpoint of suppressing resin degradation, when the resin having the largest mass ratio in each of the first resin composition, the second resin composition, and the third resin composition is polyethylene, the melt flow rate MFR1 (g / 10 min) of the first resin composition, the melt flow rate MFR2 (g / 10 min) of the second resin composition, and the melt flow rate MFR3 (g / 10 min) of the third resin composition may be 0.3 g / 10 min or more and 8.0 g / 10 min or less, or 0.4 g / 10 min or more and 7.7 g / 10 min or less, respectively.

[0047] From the viewpoint of suppressing resin degradation, when the resin having the largest mass ratio in each of the first resin composition, the second resin composition, and the third resin composition is polypropylene, the melt flow rate MFR1 (g / 10 min) of the first resin composition, the melt flow rate MFR2 (g / 10 min) of the second resin composition, and the melt flow rate MFR3 (g / 10 min) of the third resin composition may be 0.3 g / 10 min or more and 9.5 g / 10 min or less, or 0.4 g / 10 min or more and 9.0 g / 10 min or less, respectively.

[0048] From the viewpoint of achieving superior adhesion between the first and second layers and the intermediate layer, it is preferable that the first, second, and third resin compositions contain the same type of resin. In this case, each layer of the laminate is composed of the same type of resin, which facilitates recycling. The resin referred to here may be a recycled resin or a virgin resin. The first, second, and third resin compositions contain the same type of resin, meaning that the resin with the largest mass ratio in each resin composition is the same type of resin. For example, if the resin with the largest mass ratio in the intermediate layer is a polyethylene-based resin, the first and second layers may contain a polyethylene-based resin, or the polyethylene-based resin may be the main component (e.g., 90% by mass or more in the first and second layers). Furthermore, if the resin with the largest mass ratio in the intermediate layer is a polypropylene-based resin, the first and second layers may contain a polypropylene-based resin, or the polypropylene-based resin may be the main component (e.g., 90% by mass or more in the first and second layers).

[0049] To impart desired performance such as viscosity adjustment and mechanical properties, the first resin composition, the second resin composition, and the third resin composition may each 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 aids, slip agents, antiblocking agents, antifogging agents, lubricants, tackifiers, pigments, dyes, dispersants, copper inhibitors, neutralizing agents, bubble inhibitors, weld strength improvers, natural oils, synthetic oils, waxes, etc. One type of additive may be used alone, or two or more types may be used in combination.

[0050] The compatibilizer may be a reactive or non-reactive compatibilizer, and examples thereof include acid-modified polyolefin resins, ethylene-vinyl acetate copolymers, ethylene-methyl methacrylate copolymers, and ethylene-vinyl alcohol copolymers.

[0051] 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).

[0052] Examples of the antioxidant include phenolic compounds, organic phosphite compounds, and thioether compounds.

[0053] Examples of the heat stabilizer include hindered amine compounds.

[0054] Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, and benzoate compounds.

[0055] Examples of the antistatic agent include nonionic compounds, cationic compounds, and anionic compounds.

[0056] 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.

[0057] Examples of the flame retardant aid include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, and clay silicates.

[0058] 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.

[0059] <First and second layers> The thickness of each of the first and second layers may be 5 μm or more, which can prevent the shear stress applied to the interface from increasing and prevent turbulence from occurring at the interface.

[0060] From the viewpoint of suppressing the occurrence of disorder at the interface and obtaining a laminate in which yellowing is further suppressed, the thickness of each of the first layer and the second layer may be 5 μm or more, and the thickness of the entire laminate may be 150 μm or less.

[0061] The thickness of each layer constituting the laminate may be measured in the width direction of the laminate (the direction perpendicular to the flow direction during film production).

[0062] <Middle class> The thickness of the intermediate layer may be 140 μm or less. When the thickness of the intermediate layer is 140 μm or less, the first and second layers can be thickened while keeping the thickness of the laminate at 150 μm or less. When the first and second layers are thickened, an increase in shear stress at the interface can be suppressed, and interface disturbance can be further suppressed. Furthermore, when the thickness of the intermediate layer is 140 μm or less, costs can be easily suppressed.

[0063] The thickness of the entire laminate 1 is preferably 150 μm or less, in which case the YI value of the entire laminate is small, and a laminate in which yellowing is further suppressed can be obtained.

[0064] In order to obtain a laminate that is more inhibited from yellowing, the YI value per unit thickness of the entire laminate is 0 to 9 mm. -1 may be.

[0065] [Method of manufacturing laminate] The laminate of this embodiment can be produced by a conventionally known method, such as extrusion laminating a film containing a recycled material formed from a third resin composition that forms an intermediate layer with the first resin composition that forms the first layer and the second resin composition that forms the second layer, or coextrusion molding to form the intermediate layer, the first layer, and the second layer.

[0066] In the method for producing a laminate of this embodiment, the recycled material may be a post-industrial recycled material or a post-consumer recycled material.

[0067] In the former method, a film containing recycled material constituting an intermediate layer can be produced by melting the third resin composition in an injection molding machine or extrusion molding machine (e.g., a twin-screw extruder) and then forming the film in a T-die via a feed block or multi-manifold, or by an inflation method. The recycled material can be obtained by collecting, cleaning, and pulverizing various types of plastic waste, melt-molding them in an extruder, and pelletizing them. For extrusion lamination, an extrusion laminating machine or the like can be used.

[0068] In the latter method, for example, a laminate can be produced by melt-kneading and co-extruding the third resin composition forming the intermediate layer, the first resin composition forming the first layer, and the second resin composition forming the second layer using a multi-layer extrusion molding machine.

[0069] When mixing recycled and virgin materials in each resin composition, the recycled and virgin materials may be mixed in a dry blend in which they are simultaneously put into a hopper and melt-kneaded to form a film, or the recycled and virgin materials may be melt-kneaded separately in a twin-screw extruder to form a masterbatch in which they are melt-kneaded.

[0070] The cooling method for the laminate can be selected according to 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.

[0071] The laminate of this embodiment can also be produced by a method using heat pressing. In the heat pressing method, 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 compression pressure. Single-layer films produced by heat pressing can be stacked and then heat pressed again to form a laminate, or a pre-laminated flat film can be prepared and the film thickness can be adjusted by heat pressing.

[0072] The laminate may be subjected to a surface modification treatment to improve suitability for subsequent processes. For example, 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 surface modification treatments include methods for oxidizing the laminate surface, such as corona discharge treatment, plasma treatment, and flame treatment, to develop functional groups, and wet process modifications such as coating with an easy-adhesion layer.

[0073] A method for producing a laminate according to one embodiment of the present disclosure includes extrusion laminating or co-extrusion molding a first resin composition forming a first layer, a second resin composition forming a second layer, and a third resin composition forming an intermediate layer to obtain a laminate in which the first layer, the intermediate layer, and the second layer are laminated in this order. The process includes recycling a portion of the laminate as a recycled material into at least the third resin composition out of the first, second, and third resin compositions. The process also includes recycling a portion of the laminate into at least the third resin composition out of the first, second, and third resin compositions, so that the recycled material has a YI value per unit film thickness of 9 mm when formed. -1 and recycling the recycled material into at least one of the first resin composition and the second resin composition when the recycled material satisfies the following conditions: In the above step, the ratio [MFR1 / MFR3] of the melt flow rate MFR1 (g / 10 min) of the first resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12, and the ratio [MFR2 / MFR3] of the melt flow rate MFR2 (g / 10 min) of the second resin composition to the melt flow rate MFR3 (g / 10 min) of the third resin composition is 0.3 to 12. Such a laminate manufacturing method can further reduce the environmental impact and manufacture a laminate that contains recycled material and has a homogeneous and sufficiently transparent structure.

[0074] The step of obtaining a laminate in the method for manufacturing a laminate according to one embodiment of the present disclosure described above may include recycling a portion of the laminate as recycled material into at least one of the first resin composition and the second resin composition, from the viewpoint of further reducing the environmental burden, or may include recycling into the first resin composition and the second resin composition.

[0075] In the step of obtaining a laminate in the method for producing a laminate according to one embodiment of the present disclosure, from the viewpoint of further reducing the environmental load, the recycled material is used to form a film having a YI value per unit thickness of 9 mm. -1 In the following cases, the recycled material may be recycled into the first resin composition and the second resin composition.

[0076] In the step of obtaining the laminate in the method for producing the laminate according to the embodiment of the present disclosure, the recycled material is used to form a film having a YI value per unit film thickness of 9 mm. -1 If the recycled material exceeds the above range, the recycled material may be recycled into a third resin composition.

[0077] The method for producing the laminate is not limited to the above-mentioned method, and the laminate formed by the molding machine may be subjected to an in-line or off-line stretching treatment. There are no limitations on the addition of other necessary steps or additives as appropriate.

[0078] [Sealant film] The sealant film of this embodiment includes the laminate of this embodiment described above.

[0079] [Packaging material] The packaging material of this embodiment includes the laminate of this embodiment described above. Fig. 2 is a schematic cross-sectional view showing one embodiment of the packaging material. The packaging material 6 shown in Fig. 2 includes the laminate 1, a first base film 2 laminated onto the main surface of the laminate 1 on the first layer 11 side via an adhesive layer 5, and a second base film 4 having a printed layer 3 laminated onto the first base film 2 via the adhesive layer 5.

[0080] The base films 2 and 4 are not particularly limited as long as they have mechanical strength and dimensional stability, and examples of usable materials include plastic films, paper, nonwoven fabrics, etc. Examples of materials constituting the plastic films include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, polystyrene, polyamides such as 6-nylon, polycarbonate, polyacrylonitrile, polyimides, etc. From the viewpoint of ease of recycling, polyolefins such as polyethylene and polypropylene are preferred.

[0081] The adhesive constituting the adhesive layer is not particularly limited, but may be a dry laminating adhesive, such as a two-component curing urethane adhesive, a polyester urethane adhesive, a polyether urethane adhesive, an acrylic adhesive, a polyester adhesive, a polyamide adhesive, or an epoxy adhesive.

[0082] The packaging material of this embodiment may further be provided with a gas barrier film (or gas barrier layer). In this case, the barrier properties for protecting the packaging material from gases such as oxygen contained in the air, water vapor, the enclosed contents, etc. can be improved. Examples of the gas barrier film include metal foils such as aluminum foils, and laminated films of metal foils and plastic films. Examples of the gas barrier film include transparent vapor-deposited films having a vapor-deposited layer of inorganic oxide or metal on a plastic film. Examples of the plastic film include those described above, and examples of the transparent vapor-deposited film include vapor-deposited films of metal oxides such as silicon oxide and aluminum oxide. Examples of the gas barrier film include films of ethylene-vinyl alcohol copolymers, polyamide resins, polyvinylidene chloride resins, polyacrylonitrile resins, etc. In this embodiment, when a transparent vapor-deposited film is used as the gas barrier film, some of the substrate films and adhesive layers may not be provided.

[0083] The packaging material of this embodiment is not limited to the configuration shown in FIG. 2 , and may, for example, comprise a laminate 1 and a first base film 2 laminated onto the laminate 1 via an adhesive layer 5; a laminate 1, a first base film 2 laminated onto the laminate 1 via an adhesive layer 5, and a gas barrier layer provided on the first base film 2; or a laminate 1, a first base film 2 laminated onto the laminate 1 via the adhesive layer 5, and two or more functional layers, such as a gas barrier layer or a printed layer, provided on the first base film 2.

[0084] Each layer in the packaging material of this embodiment may contain the additives described above.

[0085] From the viewpoint of material recycling, the mass of plastic material contained in the packaging material of this embodiment may be 10% by mass or more, 13% by mass or more, or 25% by mass or more, based on the total mass of plastic material in the packaging material. In other words, the packaging material of this embodiment may contain recycled material in an amount, converted into plastic material mass, of 10% by mass or more, 13% by mass or more, or 25% by mass or more, based on the total amount of plastic material in the packaging material. When the packaging material of this embodiment is a laminate packaging material, materials other than plastic (for example, adhesives, printing inks, aluminum foil, etc.) may be excluded from the mass calculation.

[0086] Examples of plastic materials contained in recycled materials (so-called recycled plastics) include resins contained in recycled materials contained in the layer containing recycled materials according to the present embodiment. The mass of post-industrial plastics among recycled plastics may be calculated by multiplying the mass by 1 / 2.

[0087] The packaging material of this embodiment can be used for stand-up pouches, three-sided bags, two-sided bags, gusseted bags, pouches with spouts, pouches with beaks, and the like.

[0088] [Packaging bag] The packaging bag of this embodiment is produced by manufacturing the packaging material of this embodiment described above. The manufacturing style of the packaging bag is not particularly limited, and the packaging bag may be a stand-up pouch, a three-sided bag, a two-sided bag, a gusset bag, a pouch with a spout, a pouch with a beak, or the like.

[0089] Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments. In addition, the above-described embodiments may be used in combination as desired. [Example]

[0090] The present disclosure will be described in more detail with reference to the following examples, but the present disclosure is not limited to these examples.

[0091] <Preparing recycled materials> (Recycled material A1) LLDPE pellets (manufactured by Japan Polyethylene Co., Ltd., product name: NH745N, hereinafter also referred to as "virgin material 1") were extruded into strands using a twin-screw extruder, and the strands were cut and formed into granules, thereby obtaining recycled material A1.

[0092] (Recycled material A2) Virgin material 1 was extruded into strands using a twin-screw extruder, and the strands were cut and shaped into granules to obtain a recycled material. The same procedure as for obtaining a recycled material from virgin material 1 was repeated twice using the obtained recycled material to obtain recycled material A2.

[0093] (Recycled material A3) Recycled material A3 was obtained by the same procedure as that for obtaining recycled material A2, except that the operation was repeated four times.

[0094] (Recycled material B1) Recycled material B1 was obtained by the same procedure as that for obtaining recycled material A1, except that LLDPE pellets (manufactured by Prime Polymer Co., Ltd., product name "SP2020", hereinafter also referred to as "virgin material 2") were used instead of virgin material 1.

[0095] (Recycled material B2) Recycled material B2 was obtained by the same procedure as that for obtaining recycled material A2, except that virgin material 2 was used instead of virgin material 1.

[0096] (Recycled material B3) Recycled material B3 was obtained by the same procedure as that for obtaining recycled material A3, except that virgin material 2 was used instead of virgin material 1.

[0097] (Recycled Material C1) Instead of virgin material 1, a resin mixture (hereinafter also referred to as "virgin material 3") obtained by mixing 70 parts by mass of a propylene homopolymer and 30 parts by mass of a propylene-ethylene random copolymer in a pellet state was used, and Recycled Material C1 was obtained by the same procedure as the procedure for obtaining Recycled Material A1, except for this.

[0098] <Measurement of MFR> For virgin materials 1 to 3, recycled materials A1 to A3, B1 to B3, and C1, in accordance with JIS K7210, using a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd., the MFR (g / 10 min) was measured under the conditions of a temperature of 190°C and a load of 2.16 kg. The results are shown in Table 1.

[0099] <Measurement of YI value per unit film thickness> For each of the prepared virgin materials and recycled materials, a film formed by the following procedure was obtained. First, a PET film subjected to a release treatment was attached to an aluminum plate, and 1 g of the material was placed in the center of the PET film subjected to the release treatment. Next, using a 200-μm spacer, the recycled material was sandwiched and held between aluminum plates from above and below, and heated at 120°C for 3 minutes. Next, under a pressure of 100 kgf / cm 2 , after heating at 120°C for 1 minute, it was cooled to obtain a formed film.

[0100] The YI value of the formed film was measured in accordance with JIS K7373:2006 using a spectral color haze meter COH7700 manufactured by Nippon Denshoku Industries Co., Ltd. under the conditions of a D65 light source and a 2° field of view. The measured YI value was divided by the film thickness (mm) at the measurement location to obtain the YI value per unit film thickness (mm -1 ). The results are shown in Table 1.

[0101] [[ID=·25]]

Table 1

[0102] <Preparation of laminate> (Example 1) Recycled material A1 was placed as the third resin composition in the hopper extruding the intermediate layer, and virgin material 1 was placed as the first and second resin compositions in the hopper extruding the first and second layers, and a laminate having a first layer / intermediate layer / second layer structure was produced by co-extrusion molding using a single-screw multi-layer extruder. The thickness of the first layer was 50 μm, the thickness of the second layer was 50 μm, and the thickness of the intermediate layer was 50 μm.

[0103] Example 2 A laminate was produced in the same manner as in Example 1, except that the thickness of the first layer was 65 μm, the thickness of the second layer was 65 μm, and the thickness of the intermediate layer was 20 μm.

[0104] Example 3 A laminate was produced in the same manner as in Example 1, except that the thickness of the first layer was 5 μm, the thickness of the second layer was 5 μm, and the thickness of the intermediate layer was 140 μm.

[0105] Example 4 A laminate was produced in the same manner as in Example 1, except that the thickness of the first layer was 5 μm, the thickness of the second layer was 50 μm, and the thickness of the intermediate layer was 95 μm.

[0106] Example 5 A laminate was produced in the same manner as in Example 1, except that recycled material A2 was charged as the third resin composition into the hopper for extruding the intermediate layer.

[0107] Example 6 A laminate was produced in the same manner as in Example 1, except that recycled material A3 was charged as the third resin composition into the hopper for extruding the intermediate layer.

[0108] Example 7 A laminate was produced in the same manner as in Example 1, except that recycled material A1 was charged as the first and second resin compositions into the hoppers for extruding the first and second layers.

[0109] Example 8 A laminate was produced in the same manner as in Example 1, except that recycled material B1 was charged as the third resin composition into the hopper for extruding the intermediate layer.

[0110] Example 9 A laminate was produced in the same manner as in Example 1, except that recycled material B2 was charged as the third resin composition into the hopper for extruding the intermediate layer.

[0111] Example 10 A laminate was produced in the same manner as in Example 1, except that recycled material B1 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material A1 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0112] Example 11 A laminate was produced in the same manner as in Example 1, except that recycled material A1 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material B1 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0113] Example 12 A laminate was produced in the same manner as in Example 1, except that recycled material B1 was added as the third resin composition to the hopper extruding the intermediate layer, and virgin material 2 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0114] Example 13 A laminate was produced in the same manner as in Example 1, except that recycled material B1 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material B1 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0115] Example 14 A laminate was produced in the same manner as in Example 1, except that recycled material B2 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material B2 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0116] Example 15 A laminate was produced in the same manner as in Example 1, except that recycled material C1 was added as the third resin composition to the hopper extruding the intermediate layer, and virgin material 3 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0117] Example 16 A laminate was produced in the same manner as in Example 1, except that recycled material C1 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material C1 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0118] (Comparative Example 1) A laminate was produced in the same manner as in Example 1, except that virgin material 1 was charged as the third resin composition into the hopper for extruding the intermediate layer.

[0119] (Comparative Example 2) A laminate was produced in the same manner as in Example 1, except that recycled material B3 was charged as the third resin composition into the hopper for extruding the intermediate layer.

[0120] (Comparative Example 3) A laminate was produced in the same manner as in Example 1, except that recycled material A3 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material A3 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0121] Comparative Example 4 A laminate was produced in the same manner as in Example 1, except that virgin material 1 was added as the third resin composition to the hopper extruding the intermediate layer, and recycled material B1 was added as the first and second resin compositions to the hopper extruding the first and second layers.

[0122] <Haze value measurement> For each of the laminates of the Examples and Comparative Examples, the haze value was measured in accordance with JIS K7136:2000 using a spectral color haze meter COH7700 manufactured by Nippon Denshoku Industries Co., Ltd. under conditions of a D65 light source and a 2° field of view. A lower haze value indicates better transparency. A haze value of 20% or less was evaluated as "A," and a haze value exceeding 20% ​​was evaluated as "B." The results are shown in Tables 2 to 6.

[0123] <Evaluation of interface disturbance> The laminates of each example and comparative example were evaluated for interfacial disturbance using the following evaluation test. As shown in Figure 3, a transparent container 7 filled with water 8 was prepared, and laminate 1A held between paper clips 9 was immersed in the water. Next, laminate 1A in the water was observed from the side of container 7, and if the paper clip 9 on the back side of the laminate was not blurred, it was evaluated as "A," and if it was blurred, it was evaluated as "B." The results are shown in Tables 2 to 6.

[0124] <Evaluation of the percentage of recycled materials used> For the laminates of each Example and Comparative Example, when the mass ratio (usage ratio) of recycled material contained in the entire laminate was 10% or more, it was rated as "A", and when it was less than 10%, it was rated as "B". The results are shown in Tables 2 to 6.

[0125] [Table 2]

[0126] [Table 3]

[0127] [Table 4]

[0128] [Table 5]

[0129] [Table 6]

[0130] As shown in Tables 2 to 6, it was confirmed that the laminates of Examples 1 to 16 had homogeneous quality and sufficient transparency despite containing recycled materials. [Explanation of symbols]

[0131] 1, 1A... laminate, 2... first base film, 3... printing layer, 4... second base film, 5... adhesive layer, 6... packaging material, 11... first layer, 12... intermediate layer, 13... second layer, 7... container, 8... water, 9... paper clip.

Claims

1. a first layer formed from a first resin composition, a second layer formed from a second resin composition, and an intermediate layer formed from a third resin composition and disposed between the first layer and the second layer; at least the third resin composition among the first resin composition, the second resin composition, and the third resin composition contains a recycled material; When the first resin composition contains recycled materials, the YI value per unit film thickness when formed into a film is 9 mm －１ is as follows: When the second resin composition contains recycled materials, the YI value per unit film thickness when formed into a film is 9 mm －１ is as follows: Melt flow rate MFR of the third resin composition ３ (g / 10 min) of the melt flow rate MFR of the first resin composition １ (g / 10 min) [MFR １ / MFR ３ ] is 0.3 to 12, Melt flow rate MFR of the third resin composition ３ (g / 10 min) of the melt flow rate MFR of the second resin composition ２ (g / 10 min) [MFR ２ / MFR ３ ] is 0.3 to 12.

2. The laminate according to claim 1 , wherein the first resin composition and the second resin composition contain recycled materials.

3. The laminate according to claim 1 , wherein the recycled material is a polyolefin resin.

4. the thickness of the first layer and the second layer is 5 μm or more, 2. The laminate according to claim 1, wherein the thickness of the entire laminate is 150 μm or less.

5. 10. The laminate of claim 1, wherein the recycled material is post-industrial recycled material.

6. The YI value per unit thickness of the entire laminate is 0 to 9 mm. －１ The laminate according to claim 1 ,

7. The laminate according to claim 1 , wherein the first resin composition, the second resin composition, and the third resin composition contain the same type of resin.

8. A sealant film comprising the laminate according to any one of claims 1 to 7.

9. A packaging material comprising the laminate according to any one of claims 1 to 7.

10. A packaging bag produced from the packaging material according to claim 9.

11. a step of extrusion laminating or co-extrusion molding a first resin composition forming a first layer, a second resin composition forming a second layer, and a third resin composition forming an intermediate layer to obtain a laminate in which the first layer, the intermediate layer, and the second layer are laminated in this order; the step includes recycling a part of the laminate as a recycled material into at least the third resin composition among the first resin composition, the second resin composition, and the third resin composition, In the process, the recycled material is formed into a film having a YI value per unit film thickness of 9 mm －１ The method includes recycling the recycled material into at least one of the first resin composition and the second resin composition when the recycled material is: In the above step, the melt flow rate MFR of the third resin composition ３ (g / 10 min) of the melt flow rate MFR of the first resin composition １ (g / 10 min) [MFR １ / MFR ３ ] is 0.3 to 12, and the melt flow rate MFR of the third resin composition ３ (g / 10 min) of the melt flow rate MFR of the second resin composition ２ (g / 10 min) [MFR ２ / MFR ３ ] is 0.3 to 12.

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