Recycled resin composition, film, laminate, packaging material and packaging bag, and method for producing film

Abstract

To provide a recycled resin composition which contains a recycled material, is hardly deteriorated in processability even when recycled, and can form a film having sufficient impact resistance and good appearance, and to provide a film, a laminate, a packaging material and a packaging bag using the same.SOLUTION: The recycled material has an oxidation-induction time of 60 minutes or more and 180 minutes or less as measured at 220 °C in an oxidizing atmosphere in accordance with JISK7351.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a recycled resin composition, a film, a laminate, a packaging material and a packaging bag, and a method for producing a film. [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, and building materials. Specific materials include thermoplastic resins such as polyethylene, polypropylene, polystyrene, acrylic polymethyl methacrylate, polycarbonate, polyamide, polyethylene terephthalate, and polybutylene terephthalate, as well as thermosetting resins such as epoxy resin, polyurethane, and polyimide.

[0003] In recent years, growing environmental awareness has led to expectations for the recycling of plastic products. Among these, there is a demand for material recycling, such as post-industrial recycling (PIR), in which waste materials from manufacturing are collected and reused in the same or different products, and post-consumer recycling (PCR), in which plastics are collected and reused after consumption as products. Patent Document 1 listed below discloses technology related 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 can be obtained through various processes such as crushing, washing, filtration, and extraction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 124229 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, resin films are produced by forming a film from a molten resin using a method such as extrusion molding or cast molding. When waste materials from the production of such resin films are recycled, if the melting properties of the recycled resin change significantly, the flow of the molten resin during extrusion molding or injection molding changes, resulting in poor processability, such as impaired film width and film smoothness. On the other hand, from the viewpoint of product stabilization, resin films containing recycled materials are required to have sufficient physical properties such as impact resistance and a good appearance with sufficiently little yellowing or haze.

[0006] The present disclosure has been made in view of the above circumstances, and aims to provide a recycled resin composition that contains recycled materials and is capable of forming a film that is resistant to deterioration in processability even when recycled, and that has sufficient impact resistance and a good appearance, as well as a film, laminate, packaging material, and packaging bag using the same. Another aim of the present disclosure is to provide a method for producing the film. [Means for solving the problem]

[0007] In order to solve the above problems, the present disclosure provides the following recycled resin composition, film, laminate, packaging body, and packaging bag. The present disclosure also provides a method for producing a film.

[0008] [1] A recycled resin composition containing a recycled material containing resin, the oxidation induction time of which, measured in accordance with JIS K 7351 at 220°C under an oxygen atmosphere, is 60 minutes or more and 180 minutes or less. [2] The recycled resin composition according to [1], wherein the recycled material contains a polyolefin resin and at least one antioxidant selected from the group consisting of a phenolic antioxidant and a phosphorus-based antioxidant, and the content of the polyolefin resin is 80 mass% or more based on the total amount of the resin composition. [3] The recycled resin composition according to [1] or [2], further comprising a virgin resin of the same type as the resin contained in the recycled material. [4] The recycled resin composition according to any one of [1] to [3], wherein the recycled material is a post-industrial recycled material. [5] The recycled resin composition according to any one of [1] to [3], wherein the recycled material is a post-consumer recycled material. [6] A film formed from the resin composition according to any one of [1] to [5]. [7] A laminate comprising the film according to [6]. [8] A packaging material comprising the laminate described in [7]. [9] A packaging bag made from the packaging material described in [8].

[10] A method for producing a film, comprising a step of extruding the recycled resin composition according to any one of [1] to [5] to obtain a film.

[11] A method for producing a film, comprising: a first step of extruding a first resin composition containing a resin and an antioxidant to obtain a first film; and a second step of extruding a recycled resin composition containing at least a portion of the first film as a recycled material to obtain a second film, wherein the recycled resin composition has an oxidation induction time of 60 minutes or more and 180 minutes or less, measured in accordance with JIS K 7351 at 220°C in an oxygen atmosphere.

[12] The method for producing a film according to

[11] , wherein the resin contained in the first resin composition is a polyolefin resin that is a virgin resin, and the antioxidant contained in the first resin composition is at least one selected from the group consisting of phenolic antioxidants and phosphorus-based antioxidants. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a recycled resin composition that contains recycled materials and is capable of forming a film that is resistant to deterioration in processability even when recycled, and that has sufficient impact resistance and a good appearance, as well as a film, laminate, packaging material, and packaging bag using the same. The present disclosure also provides a method for producing the film. [Brief explanation of the drawings]

[0010] [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 laminate according to the present disclosure. [Figure 3] FIG. 3 is a cross-sectional view schematically illustrating one embodiment of a laminate according to the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view schematically illustrating one embodiment of a laminate according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. Note that Figures 1 to 4 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 invention, and the technical idea of ​​the present invention is not limited to the following in terms of component materials, shapes, structures, etc. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0012] <Recycled resin composition> The recycled resin composition of the present embodiment includes a recycled material containing a resin, and has an oxidation induction time measured in accordance with JIS K 7351 at 220° C. in an oxygen atmosphere of 60 minutes or more and 180 minutes or less.

[0013] (recycled materials) Examples of recyclable materials include post-consumer recycled (PCR) products such as bottles and packaging bags for beverages, detergents, and seasonings collected from the market, 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-industry recycled (PIR) products 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.

[0014] 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.

[0015] Resins contained in recycled materials include thermoplastic resins, thermosetting resins, and cured products thereof (including crosslinked products).

[0016] 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.

[0017] 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.

[0018] The recycled material may be a single material or may contain multiple materials. In this embodiment, when the recycled material contains multiple materials, the material that accounts for the largest proportion of the constituent materials is called the main constituent material, and materials that are not the same type as the main constituent material are called secondary constituent materials. Examples of the main constituent material include the resins described above.

[0019] The type of resin contained in the recycled material can be confirmed using a microscopic infrared spectrophotometer or the like.

[0020] The resin content of the recycled material can be measured using a known method such as an extraction method.

[0021] Examples of secondary constituent materials in recycled materials containing multiple materials include ink, adhesives, thermoplastic resins other than the primary constituent material, aluminum, alumina, silica, etc. The secondary constituent materials may contain two or more of these. The secondary constituent materials may also be mixed and dispersed in the primary constituent material, or may be contained in a separate layer laminated on the layer containing the primary constituent material.

[0022] From the viewpoint of use in a sealant layer and adhesion to other layers, the recycled material may contain a polyolefin resin, in which case the content of the polyolefin resin may be 80% by mass or more, or 90% by mass or more, based on the total amount of the recycled resin composition.

[0023] The recycled material may contain, in addition to the polyolefin resin, other resins other than the polyolefin resin. Examples of the other resins include polyester resins and polyamide resins. When the recycled material contains the other resins, the content of the other resins may be 20% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less, based on the total amount of the recycled resin composition.

[0024] The recycled resin composition of the present embodiment may contain an antioxidant. In this case, the above-mentioned recycled material may contain an antioxidant. The antioxidants may be used alone or in combination of two or more.

[0025] Examples of the antioxidant include phenol-based antioxidants and phosphorus-based antioxidants.

[0026] Phenolic antioxidants include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], thiodiethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-hexane-1,6-diylbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], amide], 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane), 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid), 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol, Diethyl [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate, 3,3',3”,5,5',5”-hexa-t-butyl-a,a',a”-(mesitylene-2,4,6-triyl)tri-p-cresol, hexamethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine -2,4,6(1H,3H,5H)-trione, etc. Commercially available phenolic antioxidants include Irganox 1010 (manufactured by BASF Japan Ltd.), Irganox 1076 (manufactured by BASF Japan Ltd.), Irganox 1098 (manufactured by BASF Japan Ltd.), Irganox 565 (manufactured by BASF Japan Ltd.), Cyanox 1790 (manufactured by Solvay), and Adekastab AO-80 (manufactured by ADEKA Corporation).

[0027] Examples of phosphorus-based antioxidants include tris(2,4-di-t-butylphenyl)phosphite, 6,6',6"-[nitrilotris(ethyleneoxy)]tris(2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepine), bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphite, tris(mono- or dinonylphenyl)phosphite and other trisnonylphenyl phosphites, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol-diphosphite, bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethyl Examples of commercially available phosphorus-based antioxidants include ethyl ester phosphorous acid, tetrakis(2,4-di-t-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonite, and bis(2,4-di-t-butylphenyl)pentaerythritol phosphite. Examples of commercially available phosphorus-based antioxidants include Irgafos 168 (manufactured by BASF Japan Ltd.), Irgafos 12 (manufactured by BASF Japan Ltd.), Irgafos 38 (manufactured by BASF Japan Ltd.), Adeka STAB 329K (manufactured by ADEKA Corporation), Adeka STAB PEP36 (manufactured by ADEKA Corporation), Adeka STAB 2112 (manufactured by ADEKA Corporation), Hostanox P-EPQ (manufactured by Clariant Chemicals Co., Ltd.), GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.), and Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.).

[0028] The phenolic antioxidant and the phosphorus-based antioxidant may be used alone or in combination. When the antioxidant contains a phenolic antioxidant and a phosphorus-based antioxidant, the content of the phenolic antioxidant is preferably 25% by mass to 60% by mass and the content of the phosphorus-based antioxidant is preferably 40% by mass to 75% by mass, based on the total amount of antioxidants, from the viewpoint of further reducing the resin's degradation due to the synergistic effect between the two. To more easily obtain the synergistic effect, the antioxidant preferably contains pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (e.g., Irganox 1010) and tris(2,4-di-t-butylphenyl)phosphite (e.g., Irgafos 168).

[0029] The antioxidant may be a phosphorus-based antioxidant having a phenolic skeleton. An example of a phosphorus-based antioxidant having a phenolic skeleton is 6-tert-butyl-4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]propyl]-2-methylphenol, and a commercially available product thereof is Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.). Phosphorus-based antioxidants having a phenolic skeleton also fall under the category of phenolic antioxidants. Phosphorus-based antioxidants having a phenolic skeleton can exert both the effects of phenolic antioxidants (e.g., the effect of capturing radicals to stabilize resins) and phosphorus-based antioxidants (e.g., the effect of decomposing unstable peroxides to form stable compounds), and therefore may be used alone.

[0030] The content of the antioxidant may be 0.05% by mass or more and 1% by mass or less, 0.1% by mass or more and 0.95% by mass or less, or 0.35% by mass or more and 0.9% by mass or less, based on the total amount of the recycled resin composition.

[0031] The recycled resin composition of this embodiment may further contain a virgin resin of the same type as the resin contained in the recycled material. Examples of virgin resins include the same types of resins as those listed as resins contained in the recycled material. 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 can be considered to be the same type of resin. Although the polyethylene-based resin is the same type of resin, it may contain multiple resins with different melting points, melt flow rates (MFR), etc. The virgin resins can be used alone or in combination of two or more types.

[0032] The recycled material may be post-industrial recycled material, which is material that contains PIR, or post-consumer recycled material, which is material that contains PCR.

[0033] The recycled material may be pelletized. For example, the recovered material may be cut into small pieces, extruded using an extruder, cut using a pelletizer, and formed into pellets, which may be used as the recycled material.

[0034] From the viewpoint of reducing the environmental load, the content of the recycled material is preferably 10% by mass or more and 100% by mass or less, and more preferably 50% by mass or more and 100% by mass or less, based on the total amount of the recycled resin composition.

[0035] The recycled resin composition of this embodiment has an oxidation induction time of 60 minutes or more and 180 minutes or less, measured in an oxygen atmosphere at 220°C in accordance with JIS K 7351. When the oxidation induction time is 60 minutes or more, thermal degradation is suppressed even when the recycled resin composition undergoes heat-applying processes such as re-kneading and re-molding, and the processability of the recycled resin composition and the physical properties of the resulting film, such as impact resistance, are more likely to be maintained. On the other hand, when the oxidation induction time is 180 minutes or less, yellowing and clouding of the film due to discoloration and bleed-out of the antioxidant can be suppressed, making it easier to obtain a film with a good appearance.

[0036] The oxidation induction time can be measured, for example, using a chemiluminescence analyzer (Tohoku Electronics Industry Co., Ltd.: Model No. CLA-FS54) according to the following procedure in accordance with JIS K 7351. The resin composition to be measured is pelletized to prepare an elliptical cylindrical measurement sample (height: approximately 3 mm, minor axis diameter: approximately 2 mm, major axis diameter: approximately 2.5 mm). Next, a certain amount of the measurement sample is weighed into an aluminum sample container with a diameter of 20 to 30 mm, and the oxidation induction time can be measured by observing the change in luminescence intensity using a chemiluminescence analyzer. The measurement conditions are as follows: measurement sample weight: 0.2 g, temperature: constant at 220°C, oxygen atmosphere, oxygen flow rate: 50 mL / min, exposure time: 1 second, and measurement time: 7 hours.

[0037] A chemiluminescence analyzer is a measuring device that detects the amount of chemiluminescence of a sample, and the oxidation induction time is the time required for the amount of luminescence to increase significantly when measured in an oxygen atmosphere. For example, in the case of a resin composition containing a polyolefin resin and an antioxidant, the oxidation induction time is the time required from the start of heating to the end of the effect of the antioxidant, etc., in suppressing chemiluminescence; the longer the time, the more resistant the polyolefin resin tends to be to oxidation.

[0038] The recycled resin composition of this embodiment may have an oxidation induction time of 70 to 180 minutes, 80 to 180 minutes, or 90 to 180 minutes. When the oxidation induction time is equal to or greater than the lower limit, the resin tends to maintain its physical properties without significant deterioration even after undergoing a step in which heat is applied during remolding. When the oxidation induction time is equal to or less than the upper limit, discoloration and bleeding out of the antioxidant can be suppressed, and a molded product with good appearance tends to be obtained.

[0039] The recycled resin composition of the present embodiment may contain, as necessary, additives such as compatibilizers, nucleating agents, reinforcing fillers, weathering agents, light stabilizers, plasticizers, UV absorbers, antistatic agents, flame retardants, flame retardant aids, slip agents, antiblocking agents, antifogging agents, lubricants, 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.

[0040] 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).

[0041] Examples of the ultraviolet absorber include benzophenone compounds, benzotriazole compounds, and benzoate compounds.

[0042] Examples of the antistatic agent include nonionic compounds, cationic compounds, and anionic compounds.

[0043] 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.

[0044] Examples of the flame retardant aid include antimony compounds, zinc compounds, bismuth compounds, magnesium hydroxide, and clay silicates.

[0045] Examples of the anti-blocking agent include acrylic particles, styrene particles, styrene-acrylic particles and crosslinked products thereof, polyurethane particles, polyester particles, silicone particles, fluorine-based 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.

[0046] <Method of manufacturing recycled resin composition> The recycled resin composition of this embodiment can be produced by a conventionally known method. For example, the recycled resin composition can be obtained by mixing a recycled material, an antioxidant, a virgin resin, and additives as needed. When the oxidation induction time of the recycled material measured in the same manner as above is 60 minutes or more and 180 minutes or less, the recycled resin composition can be obtained without blending an antioxidant.

[0047] When the recycled resin composition is used to form a film, it is preferable to process the composition into pellets because handling is improved when the composition is in a pelletized state. Examples of production methods include dry blending the composition in a blender, squeezing the mixture into pellets, or melt-molding the mixture into strings using a single-screw extruder or twin-screw extruder, and then cutting the strings into pellets. From the viewpoint of dispersibility of antioxidants and virgin resins, it is preferable to produce the recycled resin composition by extrusion molding, which is expected to provide high dispersibility, and twin-screw extrusion molding is more preferable.

[0048] <Film> The film of this embodiment is formed from the recycled resin composition of this embodiment described above. The film of this embodiment is excellent in recyclability because it is less likely to lose processability even when recycled, and has sufficient impact resistance and a good appearance.

[0049] The thickness of the film may be 20 μm or more, 50 μm or more, or 100 μm or more. The thickness of the film may be 200 μm or less, 150 μm or less, or 120 μm or less. The thickness of the film may be 20 to 200 μm, 50 to 150 μm, or 100 to 120 μm.

[0050] The film of this embodiment can be used as a sealant film for packaging materials, a part of a sealant film for packaging materials, a base film for packaging materials, or a label base material.

[0051] <Film manufacturing method> The film of this embodiment can be produced using a known method. Examples of production methods include melting the recycled resin composition of this embodiment using an injection molding machine or an extrusion molding machine (e.g., a twin-screw extruder) and forming the melt into a film using a T-die via a feed block or multi-manifold, or forming the film by an inflation method. The temperature conditions during film formation and film formation may be appropriately changed depending on the type of resin used. For example, the temperature conditions during film formation may be 170 to 280°C, and the temperature conditions during film formation may be 120 to 230°C.

[0052] Another embodiment of a film manufacturing method includes a first step of extruding a first resin composition containing a resin and an antioxidant to obtain a first film, and a second step of extruding a recycled resin composition containing at least a portion of the first film as a recycled material to obtain a second film. In this method, the recycled resin composition has an oxidation induction time of 60 to 180 minutes measured in accordance with JIS K 7351 under an oxygen atmosphere at 220°C.

[0053] The resin contained in the first resin composition may be the above-mentioned virgin resin or a resin derived from a recycled material containing resin. From the viewpoint of reducing the amount of foreign matter mixed in, the resin contained in the first resin composition may be a polyolefin-based resin, which is a virgin resin, and the antioxidant contained in the first resin composition may be at least one selected from the group consisting of phenol-based antioxidants and phosphorus-based antioxidants.

[0054] The recycled resin composition used in the second step can have the same configuration as the recycled resin composition of the present embodiment described above.

[0055] The second film obtained in the second step is highly recyclable, as it is less likely to lose processability even when recycled, and has sufficient impact resistance and a good appearance, making it particularly suitable for post-industrial recycling.

[0056] <Laminate> The laminate of this embodiment includes the film of this embodiment described above. The laminate of this embodiment may have a structure in which other layers are laminated on the film of this embodiment described above.

[0057] Examples of the other layers include a substrate layer, an intermediate layer, a heat seal layer, and a gas barrier layer. When the laminate has a sealant layer, the laminate can be used as a packaging material.

[0058] 1 to 4 are cross-sectional views schematically illustrating one embodiment of a laminate according to the present disclosure. A laminate 10 shown in FIG. 1 includes a film 11 of the present embodiment and a base layer 12. A laminate 20 shown in FIG. 2 has a structure in which a base layer 22, a film 21 of the present embodiment, and a heat-seal layer 23 are laminated in this order. A laminate 30 shown in FIG. 3 has a structure in which a base layer 32, an intermediate layer 34, a film 31 of the present embodiment, and a heat-seal layer 33 are laminated in this order. A laminate 40 shown in FIG. 4 has a structure in which a base layer 42, a gas barrier layer 45, a film 41 of the present embodiment, and a heat-seal layer 43 are laminated in this order.

[0059] (base material layer) The base layer may be formed from a polyolefin resin such as polypropylene or polyethylene, from the viewpoint of imparting shielding properties, stiffness, and printability to the laminate, and may be double-sided art paper, single-sided art paper, double-sided coated paper, or single-sided coated paper laminated with a printing primer coating layer.

[0060] The thickness of the substrate layer may be, for example, 5 to 30 μm, or 30 to 100 μm.

[0061] (heat seal layer) Examples of materials for the heat seal layer include polyolefin resins such as polyethylene and polypropylene, polyester resins (for example, polyester resins having a melting point of 240° C. or less), etc. The heat seal layer can impart sealability to the laminate.

[0062] The thickness of the heat seal layer may be, for example, 50 to 200 μm, or 80 to 150 μm.

[0063] (middle class) Examples of materials for the intermediate layer include polyolefin resins, polyethylene-vinyl acetate copolymer resins, styrene copolymer resins, etc. The intermediate layer can, for example, increase the adhesion between the base layer and the film.

[0064] The thickness of the intermediate layer may be, for example, 3 to 100 μm, or 5 to 30 μm.

[0065] The gas barrier layer may be formed from, for example, a vapor-deposited film or a film made of a polymer having gas barrier properties such as a polyamide resin or a saponified ethylene-vinyl acetate copolymer, etc. The gas barrier layer can impart gas barrier properties to the laminate.

[0066] The thickness of the gas barrier layer may be, for example, 2 to 30 μm, or 10 to 20 μm.

[0067] The laminate of this embodiment can be used as a packaging material.

[0068] <Packaging material> The packaging material of this embodiment includes the laminate of this embodiment described above. The laminate may include a heat seal layer. The packaging material of this embodiment may consist solely of the laminate of this embodiment described above, or may be a product obtained by processing the laminate.

[0069] <Packaging bag> The packaging bag of this embodiment is made by manufacturing the packaging material of this embodiment described above. The packaging bag can be manufactured, for example, by bonding the heat-sealable layers of a pair of packaging materials together to form a bag, or by folding a single packaging material so that the surfaces of the heat-sealable layers face each other to form a bag. [Example]

[0070] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0071] Example 1 Antioxidant 1 (Sumitomo Chemical Co., Ltd., product name: Sumilizer GP) was added to LLDPE resin (Japan Polyethylene Corporation, product name: Harmolex NH745N) with the flow rate adjusted using a feeder so that the amount of antioxidant 1 added was 0.8 parts by mass per 100 parts by mass of LLDPE resin. The resin was extruded at 180°C using a twin-screw extruder to form a string-like resin, which was then cut into pellets using a pelletizer to obtain a virgin resin composition. This virgin resin composition was then used to produce a 150 μm film by single-screw extrusion at 230°C. This film was used as recycled material.

[0072] The obtained recycled material was extrusion-molded at 230°C using a twin-screw extruder into a string-like shape, and then cut using a pelletizer to form pellets (elliptical cylinder, height: approximately 3 mm, minor axis diameter: approximately 2 mm, major axis diameter: approximately 2.5 mm), yielding the recycled resin composition of Example 1. The oxidation induction time of the obtained recycled resin composition was measured in accordance with JIS K 7351 using a chemiluminescence analyzer (Tohoku Electronics Industry Co., Ltd.: model number: CLA-FS54) under an oxygen atmosphere under the following conditions. The oxidation induction time was 178 minutes. [Measurement conditions] Temperature: constant at 220℃ Oxygen flow rate: 50 mL / min Exposure time: 1 second Measurement time: 7 hours Measurement sample weight: 0.2g

[0073] The obtained recycled resin composition was subjected to single-screw extrusion molding in the same manner as in the production of the recycled material described above to produce a film having a thickness of 150 μm. This film was designated as the film having the first cycle.

[0074] The obtained film was then used as a recycled material, and the same process as above was repeated to produce a film, which constituted one cycle. This cycle was repeated four times to obtain a film having a thickness of 150 μm after the fifth cycle.

[0075] Example 2 Antioxidant 2 (BASF, product name: Irganox 1010) and antioxidant 3 (BASF, product name: Irgafos 168) were added to LLDPE resin (Japan Polyethylene Corporation, product name: Harmolex NH745N) with the flow rate adjusted using a feeder so that the amount of antioxidant 2 added was 0.4 parts by mass per 100 parts by mass of LLDPE resin and the amount of antioxidant 3 added was 0.4 parts by mass per 100 parts by mass of LLDPE resin. The resin was extruded at 180°C using a twin-screw extruder to form a strand of resin, which was then cut into pellets using a pelletizer to obtain a virgin resin composition. This virgin resin composition was then extruded at 230°C using a single-screw extruder to produce a 150 μm film. This film was used as recycled material.

[0076] The obtained recycled material was extrusion-molded at 230°C using a twin-screw extruder into a string-like shape, and then cut into pellets (the above-mentioned elliptical cylindrical shape) using a pelletizer to obtain a recycled resin composition of Example 2. The oxidation induction time of the obtained recycled resin composition was measured in the same manner as in Example 1, and was found to be 130 minutes.

[0077] Using the obtained recycled resin composition, films with a thickness of 150 μm were obtained after the first and fifth cycles in the same manner as in Example 1.

[0078] Example 3 A virgin resin composition, a recycled material, and a recycled resin composition were obtained in the same manner as in Example 1, except that the amount of antioxidant 1 added was adjusted to 0.4 parts by mass per 100 parts by mass of the LLDPE resin. The oxidation induction time of the obtained recycled resin composition was measured in the same manner as in Example 1, and was found to be 80 minutes.

[0079] Using the obtained recycled resin composition, films with a thickness of 150 μm were obtained after the first and fifth cycles in the same manner as in Example 1.

[0080] Example 4 Antioxidant 1 (Sumitomo Chemical Co., Ltd., product name: Sumilizer GP) was added to LLDPE resin (Japan Polyethylene Corporation, product name: Harmolex NH745N) with the flow rate adjusted using a feeder so that the amount of antioxidant 1 added was 0.5 parts by mass per 100 parts by mass of LLDPE resin. The resin was extruded at 180°C using a twin single-screw extruder to form a string-like resin, which was then cut into pellets using a pelletizer to obtain a virgin resin composition. This virgin resin composition was then extruded at 230°C using a single-screw extrusion molding machine to produce a 150 μm film, which was used as the recycled material.

[0081] The recycled material and LLDPE resin (product name: Harmolex NH745N, manufactured by Japan Polyethylene Corporation) as a virgin resin were dry-blended in a blender so that the mass ratio of recycled material to virgin resin was 6:4, and the mixture was extruded into a string shape at 180°C using a twin-screw extruder, and then cut into pellets (the above-mentioned elliptical cylinder shape) using a pelletizer to obtain a recycled resin composition of Example 4. The oxidation induction time of the obtained recycled resin composition was measured in the same manner as in Example 1, and was found to be 63 minutes.

[0082] Using the obtained recycled resin composition, films with a thickness of 150 μm were obtained after the first and fifth cycles in the same manner as in Example 1.

[0083] (Comparative Example 1) A virgin resin composition, a recycled material, and a recycled resin composition were obtained in the same manner as in Example 1, except that the amount of antioxidant 1 added was adjusted to 0.3 parts by mass per 100 parts by mass of the LLDPE resin. The oxidation induction time of the obtained recycled resin composition was measured in the same manner as in Example 1, and was found to be 55 minutes.

[0084] Using the obtained recycled resin composition, films with a thickness of 150 μm were obtained after the first and fifth cycles in the same manner as in Example 1.

[0085] (Comparative Example 2) Except for not adding an antioxidant, a virgin resin composition, a recycled material, and a recycled resin composition were obtained in the same manner as in Example 1. The oxidation induction time of the obtained recycled resin composition was measured in the same manner as in Example 1, and was found to be 1 minute.

[0086] Using the obtained recycled resin composition, films with a thickness of 150 μm were obtained after the first and fifth cycles in the same manner as in Example 1.

[0087] (Comparative Example 3) A virgin resin composition, a recycled material, and a recycled resin composition were obtained in the same manner as in Example 1, except that the amount of antioxidant 1 added was adjusted to 1.0 part by mass per 100 parts by mass of the LLDPE resin. The oxidation induction time of the obtained recycled resin composition was measured in the same manner as in Example 1, and was found to be 210 minutes.

[0088] Using the obtained recycled resin composition, films with a thickness of 150 μm were obtained after the first and fifth cycles in the same manner as in Example 1.

[0089] <Evaluation of processability of recycled resin composition> First, the melt flow rate (MFR) of the virgin resin compositions and the recycled resin compositions obtained in each Example and Comparative Example after the first and fifth cycles was measured using a melt indexer (manufactured by Toyo Seiki Seisaku-sho, Ltd., model number: F-F01) in accordance with JIS K 7210-1: 2014. The cylinder temperature was set to 190°C, and the resin compositions were placed in the cylinder. The cylinder was heated and held for 4 minutes, and then a load of 2.16 kg was applied to measure the MFR. The time interval for cutting the sample was 240 seconds when the MFR was 0.1 g / 10 min or more and 0.5 g / 10 min or less, 120 seconds when the MFR was 0.5 g / 10 min or more and 1.0 g / 10 min or less, 60 seconds when the MFR was 1.0 g / 10 min or more and 3.5 g / 10 min or less, 30 seconds when the MFR was 3.5 g / 10 min or more and 10.0 g / 10 min or less, and 5 to 15 seconds when the MFR was greater than 10.0 g / 10 min.

[0090] In film production, if the MFR of a resin composition changes, the flow of the molten resin during extrusion or injection molding changes, impairing the film width and smoothness, resulting in insufficient processability. Therefore, the processability of recycled resin compositions was evaluated based on the rate of change in melt flow rate (MFR) from the virgin resin composition. The processability of recycled resin compositions is better when the rate of change in MFR from the virgin resin composition is small. A rate of change within ±10% was evaluated as "A," and a rate of change exceeding ±10% was evaluated as "B." The results are shown in Table 1.

[0091] [Table 1]

[0092] <Evaluation of film impact resistance> For the films obtained in each Example and Comparative Example after the first and fifth cycles (hereinafter referred to as recycled films), and for the films formed from the virgin resin compositions obtained in each Example and Comparative Example (hereinafter referred to as virgin films), the force (J) when a bullet penetrated a 150 μm thick film was measured using a thermostatic chamber-equipped film impact tester (manufactured by Toyo Seiki Seisaku-sho, Ltd., model: R) under conditions of a bullet size of 1 / 2 inch, no weight, and a temperature of 23°C, and the impact strength (J / mm) was calculated.

[0093] The impact resistance of the recycled film was evaluated based on the rate of change in impact strength from that of the virgin film. In other words, the smaller the rate of change in impact strength from that of the virgin film, the better the impact resistance of the recycled film. If the rate of change was less than ±10%, it was rated "A", and if it was ±10% or more, it was rated "B". The results are shown in Table 2.

[0094] [Table 2]

[0095] <Evaluation of film appearance> The appearance of the films obtained in each of the Examples and Comparative Examples after the first and fifth cycles (hereinafter referred to as recycled films) was evaluated by a sensory test using the following two-point discrimination method.

[0096] Ten panelists were asked to compare the recycled film and the film formed from the virgin resin composition in terms of yellowing (which was yellower) and cloudiness (which was cloudier). The appearance was evaluated as "A" if fewer than eight people answered that the recycled film was yellower and fewer than eight people answered that the recycled film was cloudier. Otherwise, if eight or more people answered that the recycled film was yellower or cloudier in either the yellowing or cloudiness, a statistically significant difference was indicated and a "B" was given. The results are shown in Table 3. The numbers in Table 3 for "Yellowing" and "Cloudiness" represent the number of people who answered that the recycled film was yellower or cloudier, respectively.

[0097] [Table 3]

[0098] As shown in Tables 1 to 3, in Examples 1 to 4, films were formed that were less susceptible to deterioration in processability even when recycled, and had sufficient impact resistance and good appearance. In contrast, in Comparative Example 1, processability deteriorated with repeated recycling, in Comparative Example 2, processability, impact resistance, and appearance deteriorated when recycled, and in Comparative Example 3, appearance deteriorated when recycled. [Explanation of symbols]

[0099] 10, 20, 30, 40... laminate; 11, 21, 31, 41... film; 12, 22, 32, 42... base material layer; 23, 33, 43... heat seal layer; 34... intermediate layer; 45... gas barrier layer.

Claims

1. Contains recycled materials containing resin, A recycled resin composition having an oxidation induction time measured in accordance with JIS K 7351 in an oxygen atmosphere at 220°C of 60 minutes or more and 180 minutes or less.

2. the recycled material contains a polyolefin resin and at least one antioxidant selected from the group consisting of a phenolic antioxidant and a phosphorus-based antioxidant, The recycled resin composition according to claim 1, wherein the content of the polyolefin resin is 80 mass % or more based on the total amount of the resin composition.

3. The recycled resin composition according to claim 1, further comprising a virgin resin of the same type as the resin contained in the recycled material.

4. The recycled resin composition of claim 1 , wherein the recycled material is post-industrial recycled material.

5. The recycled resin composition according to claim 1 , wherein the recycled material is post-consumer recycled material.

6. A film formed from the recycled resin composition according to any one of claims 1 to 5.

7. A laminate comprising the film of claim 6.

8. A packaging material comprising the laminate according to claim 7.

9. A packaging bag produced from the packaging material according to claim 8.

10. A method for producing a film, comprising a step of extruding the recycled resin composition according to any one of claims 1 to 5 to obtain a film.

11. a first step of extruding a first resin composition containing a resin and an antioxidant to obtain a first film; a second step of extruding a recycled resin composition containing at least a portion of the first film as a recycled material to obtain a second film; The method for producing a film, wherein the recycled resin composition has an oxidation induction time measured in accordance with JIS K 7351 at 220°C in an oxygen atmosphere of 60 minutes or more and 180 minutes or less.

12. the resin contained in the first resin composition is a polyolefin-based resin that is a virgin resin, The method for producing a film according to claim 11, wherein the antioxidant contained in the first resin composition is at least one selected from the group consisting of phenolic antioxidants and phosphorus-based antioxidants.

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