recycled film

Abstract

To provide a recycled film with a multilayer structure having high interlayer strength. [Solution] The recycled film comprises a first resin layer and a second resin layer laminated on one side of the first resin layer. The first resin layer contains recycled resin material made from a resin molded product having a printed layer. The recycled film has a total light transmittance of less than 85% at a measurement wavelength of 400 nm, measured spectrophotometrically in accordance with JIS K0115. The average interlayer strength between the first resin layer and the second resin layer is 0.55 N / 10 mm or more.

Description

[Technical Field]

[0001] The present invention relates to recycled films. [Background technology]

[0002] In recent years, marine pollution caused by discarded plastics has become a global problem. Therefore, resource circulation, such as recycling plastic products that were previously discarded, has been attracting attention. For example, Patent Document 1 discloses a method for producing heat-shrinkable film using fluff and repellets obtained from packaging material having a printed layer as a starting material. Patent Document 2 discloses a method for producing recycled plastic (repellets) with little discoloration, foreign matter, or air bubbles after removing the printed layer from packaging material having the printed layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6849141 [Patent Document 2] Japanese Patent Application Publication No. 2023-172449 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have noticed a phenomenon in which, when a multilayer recycled film is produced using recycled resin materials such as fluff and repellets produced from plastic products, the adhesive strength (interlayer strength) between the layer containing the recycled resin material and the adjacent layer in the recycled film decreases. When the interlayer strength decreases, peeling between the layers can easily occur. Further investigation by the present inventors suggests that this phenomenon is caused by components derived from the printed layer contained in the recycled resin material.

[0005] An object of the present invention is to provide a recycled film having a multilayer structure with high interlayer strength. [Means for solving the problem]

[0006] Item 1. A first resin layer, a second resin layer laminated on one surface of the first resin layer; Equipped with the first resin layer contains a recycled resin material made from a resin molded product having a printed layer; The total light transmittance at a measurement wavelength of 400 nm measured by spectrophotometric measurement in accordance with JIS K0115 is less than 85%; The average interlayer strength between the first resin layer and the second resin layer is 0.55 N / 10 mm or more. Recycled film.

[0007] Item 2. The first resin layer contains an ultraviolet absorber in a weight ratio of 0.05% or more. Item 1. The recycled film according to item 1.

[0008] Item 3. The resin molded product contains at least one of polystyrene-based resin, polyester-based resin, polyolefin-based resin, and polyamide-based resin, Item 1 or 2. The recycled film according to item 1 or 2.

[0009] Item 4. A heat-shrinkable film. Item 4. The recycled film according to any one of items 1 to 3. [Effects of the Invention]

[0010] According to the present invention, a recycled film having a multilayer structure with high interlayer strength is provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a recycled film according to an embodiment. [Figure 2] FIG. 2 is a plan view of a product film before film selvages are cut out according to one embodiment. [Figure 3] 1 is a cross-sectional view of a product film according to one embodiment. [Figure 4]FIG. 1 is a block diagram illustrating a resource circulation system according to an embodiment. [Figure 5] FIG. 1 is a diagram showing the configuration of a film manufacturing apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a recycled film according to one embodiment of the present invention will be described with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and their description will not be repeated. Furthermore, for ease of understanding, each drawing is drawn in a schematic manner with objects appropriately omitted or exaggerated.

[0013] [1. Composition of recycled film] The recycled film 1 according to this embodiment is a packaging material in the form of a film or label that can be used in a variety of fields, including food, beverages, pharmaceuticals, medical products, chemicals, cosmetics, toiletries, industrial products, agricultural products, etc. The recycled film 1 is used to package various containers, such as plastic containers, glass containers, and paper containers.

[0014] When the above-mentioned uses are assumed, from the viewpoint of strength, the thickness of the recycled film 1 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. From the viewpoints of economy and environment, the thickness of the recycled film 1 is preferably 60 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, even more preferably 35 μm or less, and even more preferably 30 μm or less.

[0015] Furthermore, assuming the above-mentioned uses, the haze value of the recycled film 1 is preferably 14% or less, more preferably 12% or less, even more preferably 10% or less, even more preferably 8% or less, and even more preferably 7% or less, from the viewpoint of ensuring the transparency of the recycled film 1. The haze value can be measured using a haze meter (NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.) at a temperature of 23°C according to a method in accordance with JIS Z7136. The haze value can be the average value obtained by measuring multiple times using multiple samples using the above-mentioned method, and is preferably the average value obtained by measuring at least four times.

[0016] The recycled film 1 is, for example, a heat-shrinkable film. In this case, the recycled film 1 is heat-shrunk by heating and is attached to a container, for example, by adhering to the outer surface of the container along the outer shape of the container. The recycled film 1 is, for example, formed into a cylindrical shape and placed on the container so as to cover the container from the outside, and then heat-shrunk and attached to the container. The recycled film 1 is formed into a cylindrical shape, for example, by overlapping both ends in the TD (Transverse Direction) and sealing the overlapped portion in the MD (Machine Direction). In this case, when the recycled film 1 is attached to a container as a label, the TD of the recycled film 1 typically corresponds to the horizontal direction of the container, and the MD of the recycled film 1 typically corresponds to the vertical direction of the container.

[0017] Considering the above-mentioned uses, the recycled film 1 is preferably a uniaxially stretched film with the TD as the main shrinkage direction. The stretching ratio in the main shrinkage direction of the recycled film 1 is preferably 300% or more, more preferably 400% or more, and even more preferably 500% or more. The stretching ratio in the same direction is preferably 700% or less, more preferably 650% or less, and even more preferably 600% or less. On the other hand, the stretching ratio in the direction perpendicular to the main shrinkage direction of the recycled film 1 is preferably 120% or more, more preferably 125% or more, and even more preferably 130% or more. The stretching ratio in the same direction is preferably 180% or less, more preferably 170% or less, even more preferably 160% or less, even more preferably 150% or less, and even more preferably 140% or less.

[0018] The heat shrinkage rate of the recycled film 1 in the main shrinkage direction is preferably 60% or more, more preferably 65% ​​or more, and even more preferably 70% or more when immersed in 98°C hot water for 10 seconds. The heat shrinkage rate in the same direction is preferably 30% or more, more preferably 35% or more, and even more preferably 40% or more when immersed in 80°C warm water for 10 seconds. The heat shrinkage rate in the same direction is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more when immersed in 70°C warm water for 10 seconds. On the other hand, the heat shrinkage rate in the direction perpendicular to the main shrinkage direction of the recycled film 1 is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more when immersed in 98°C hot water for 10 seconds. The heat shrinkage rate in the same direction is preferably -5% or more, more preferably 0% or more, and even more preferably 2% or more when immersed in 80°C warm water for 10 seconds.

[0019] FIG. 1 is a cross-sectional view of a recycled film 1. In this example, the recycled film 1 has a three-layer structure including a first resin layer 11, a second resin layer 12, and a third resin layer 13. The first resin layer 11 is an intermediate layer and is formed between the second resin layer 12 and the third resin layer 13 in the thickness direction of the recycled film 1. In other words, the second resin layer 12 is laminated on one surface of the first resin layer 11, and the third resin layer 13 is laminated on the other surface of the first resin layer 11. The second resin layer 12 and the third resin layer 13 are each a surface layer. In other words, one of the second resin layer 12 and the third resin layer 13 forms one surface (outermost surface) of the recycled film 1, and the other forms the other surface (outermost surface) of the recycled film 1. The first resin layer 11 and the adjacent second resin layer 12 may be bonded via an adhesive layer. The first resin layer 11 and the adjacent third resin layer 13 may also be bonded via an adhesive layer. The recycled film 1 is produced, for example, by feeding the raw materials of each layer included in the recycled film 1 (the first resin layer 11, the second resin layer 12, the third resin layer 13, and the adhesive layer, if any) into an extruder and co-extruding them.

[0020] The first resin layer 11, the second resin layer 12, and the third resin layer 13 each contain a resin. The first resin layer 11, which is an intermediate layer, may contain one or more types of resin. The second resin layer 12 and the third resin layer 13, which are surface layers, may also contain one or more types of resin. The amount of resin contained in each of the first resin layer 11, the second resin layer 12, and the third resin layer 13 is preferably 50 wt% or more, more preferably 60 wt% or more, even more preferably 70 wt% or more, even more preferably 80 wt% or more, even more preferably 90 wt% or more, and even more preferably 95 wt% or more. Each of the first resin layer 11, the second resin layer 12, and the third resin layer 13 may contain an additive. Examples of additives include ultraviolet absorbers, antiblocking agents, heat stabilizers, antioxidants, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, and fluorescent brighteners.

[0021] The first resin layer 11, the second resin layer 12, and the third resin layer 13 may each contain a specific type of resin as a main component. In this specification, the term "main component" refers to the component that accounts for the largest weight of the total weight. The amount of the main component resin contained in each of the first resin layer 11, the second resin layer 12, and the third resin layer 13 is preferably 50 wt% or more, more preferably 60 wt% or more, even more preferably 70 wt% or more, even more preferably 80 wt% or more, even more preferably 90 wt% or more, and even more preferably 95 wt% or more.

[0022] Examples of the type of resin contained in each of the first resin layer 11, the second resin layer 12, and the third resin layer 13 include polystyrene-based resin, polyester-based resin, polyolefin-based resin, and polyamide-based resin.

[0023] Examples of polystyrene-based resins include homopolymers of styrene-based monomers and copolymers of styrene-based monomers with other monomers (conjugated dienes, aliphatic unsaturated carboxylic acid esters, etc.). Any resin containing a styrene-based monomer is acceptable. The styrene-based monomer referred to here includes styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, ethylstyrene, pt-butylstyrene, etc., with styrene being preferred. A single styrene-based monomer may be used, or two or more styrene-based monomers may be used in combination. Specific examples include aromatic vinyl hydrocarbon-conjugated diene copolymers, mixed resins of aromatic vinyl hydrocarbon-conjugated diene copolymers and aromatic vinyl hydrocarbon-aliphatic unsaturated carboxylic acid ester copolymers, and rubber-modified impact-resistant polystyrene. More specific examples include styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-isoprene-butadiene copolymers, styrene-acrylic copolymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, general-purpose polystyrene (GPPS), and hyperbranched polystyrene.

[0024] Examples of polyester resins include those obtained by condensation polymerization of a dicarboxylic acid component and a diol component. The type of the dicarboxylic acid component is not particularly limited, and examples include terephthalic acid, o-phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octyl succinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylenecarboxylic acid, anhydrides thereof, and lower alkyl esters thereof. The type of the diol component is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2,5- Examples include aliphatic diols such as hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, and polytetramethylene ether glycol; and alicyclic diols such as 2,2-bis(4-hydroxycyclohexyl)propane, alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

[0025] Examples of polyolefin-based resins include polypropylene-based, polyethylene-based, and cyclic polyolefin-based resins. Examples of polypropylene-based resins include binary or ternary random copolymers containing propylene as the main component and ethylene, butene, or an α-olefin as a copolymerization component. Preferred α-olefins include ethylene, 1-butene, 1-hexene, and 1-octene, and the like, and the resin may contain two or more types of α-olefins. The polypropylene-based resin may also be a mixture of different propylene-α-olefin random copolymers. Examples of polyethylene-based resins include branched low-density polyethylene resins, linear low-density polyethylene resins, high-density polyethylene resins, ethylene-vinyl acetate copolymers, ionomer resins, and mixtures thereof. Copolymers of ethylene and α-olefins are also included. Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, and 1-octene. The copolymers may be random copolymers or block copolymers. Examples of cyclic polyolefin resins include (a) copolymers of ethylene or propylene with cyclic olefins (e.g., norbornene and its derivatives, tetracyclododecene and its derivatives, etc.), (b) ring-opening polymers of the cyclic olefins or copolymers with α-olefins, (c) hydrogenated products of the polymers (b), and (d) graft-modified products of the above (a) to (c) with unsaturated carboxylic acids and their derivatives, etc. Examples of the cyclic olefins include norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, and 5-benzylnorbornene.

[0026] Examples of polyamide-based resins include aliphatic polyamides, aromatic polyamides, amorphous polyamides, and polyamide elastomers. Examples of the aliphatic polyamide include aliphatic nylon and copolymers thereof, and specific examples include polycapramide (nylon-6), poly-ω-aminoheptanoic acid (nylon-7), poly-ω-aminononanoic acid (nylon-9), polyundecaneamide (nylon-11), polylauryllactam (nylon-12), polyethylenediamineadipamide (nylon-2,6), polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (nylon-6,6), polyhexamethylenesebacamide (nylon-6,10), polyhexamethylenedodecamide (nylon-6,12), polyoctamethyleneadipamide (nylon-8,6), and polydecamethyleneadipamide (nylon-10,8).

[0027] The types of resin contained in the first resin layer 11, the second resin layer 12, and the third resin layer 13 may be the same or different from one another. Furthermore, the first resin layer 11, the second resin layer 12, and the third resin layer 13 may contain the same type of resin in different weight ratios. Note that the first resin layer 11, which is an intermediate layer, and the second resin layer 12 and the third resin layer 13, which are surface layers, are required to perform different roles, so it is preferable that they contain different types of resin as their main components.

[0028] A preferred example of the resin that serves as the main component contained in the first resin layer 11 is a polystyrene-based resin. A preferred example of the resin that serves as the main component contained in each of the second resin layer 12 and the third resin layer 13 is a polyester-based resin such as PET (Poly-Ethylene-Terephthalate).

[0029] The thickness of the first resin layer 11 is preferably 2 μm or more, and particularly when the recycled film 1 is a heat-shrinkable film, it is preferably 10 μm or more, more preferably 12 μm or more, and even more preferably 15 μm or more. The thickness of the first resin layer 11 is preferably 40 μm or less, more preferably 30 μm or less, even more preferably 25 μm or less, and even more preferably 20 μm or less.

[0030] The thickness of each of the second resin layer 12 and the third resin layer 13 is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 5 μm or more. The thickness of each of the second resin layer 12 and the third resin layer 13 is preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less. The thicknesses of the second resin layer 12 and the third resin layer 13 may be the same as or different from each other.

[0031] The first resin layer 11 contains a recycled resin raw material 3 made from a resin molded product 2 having a printed layer. The recycled resin raw material 3 is a recycled resin raw material containing printing-derived components and may be a mechanically recycled raw material or a materially recycled raw material. The printing-derived components include, for example, various pigments (colorants). The printing-derived components may include, for example, inorganic pigments such as titanium oxide (white pigment) and aluminum (silver pigment), and organic pigments such as carbon black (black pigment). The first resin layer 11 may further contain a biomass raw material. The resin molded product 2 may be a used product, an unused product, an intermediate processed product, a leftover product, scrap material, a defective product, a prototype, a discarded product, or the like. In other words, the resin molded product 2 may be a post-consumer material that has been distributed in the market and collected after use by consumers, or a pre-consumer material that has not yet been distributed to consumers. The resin molded product 2 is typically a packaging material in the form of a film or label, but its form is not critical as long as it is a resin molded product having a printed layer. For example, the resin molded product 2 may be a container such as a tray, bottle, pouch, or bag for storing an item, or may be an accessory to the container such as a cap. When the resin molded product 2 is a film or a label, the resin molded product 2 may be, for example, a printed roll of film, a film formed into a long cylindrical shape by gluing both ends of a printed film, a lead film for test printing, a film edge cut out from a printed film, or a label collected after distribution in the market. The printed layer is formed, for example, by using a gravure printing plate. The recycled resin raw material 3 may contain only one type of resin molded product 2 as a starting material, or may contain multiple types of resin molded products 2.

[0032] The resin contained in the main body portion of the resin molded product 2 other than the printed layer may be one type or multiple types. The main body portion of the resin molded product 2 other than the printed layer preferably contains at least one type of polystyrene-based resin, polyester-based resin, polyolefin-based resin, or polyamide-based resin. Details of the polystyrene-based resin, polyester-based resin, polyolefin-based resin, and polyamide-based resin in the resin molded product 2 are the same as those described for the resins contained in the first resin layer 11, the second resin layer 12, and the third resin layer 13. The main body portion of the resin molded product 2 other than the printed layer may also contain additives. Examples of additives include ultraviolet absorbers, antiblocking agents, heat stabilizers, antioxidants, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, and fluorescent brighteners.

[0033] An example of the resin molded product 2 described above is a film edge, as shown below. Hereinafter, the film edge will also be referred to as 2. The film edge 2 is a narrow, long waste film and is cut out from a wide, long product film 5 shown in FIG. 2. As shown in FIG. 2, the product film 5 includes a product portion 50 and film edge portions 2, 2 adjacent to both ends of the product portion 50 in the width direction. While FIG. 2 shows the product film 5 in an unfolded state, the product film 5 is wound up and managed in the form of a roll for storage and handling. The product portion 50 is used to package various containers, such as plastic containers, glass containers, and paper containers. Before shipping the product portion 50, the film edge portions 2, 2 are separated from the product portion 50 by cutting the product film 5 along the boundary between the product portion 50 and the film edge portions 2, 2. The product portion 50 and the film edge portions 2, 2 are also wound up and managed in the form of a roll for storage and handling.

[0034] FIG. 3 shows a cross-sectional view of the product film 5. As shown in the figure, the product film 5, as well as the product portion 50 and film selvages 2, 2 cut out from the product film 5, have a resin film main body 51 and a printed layer 52 laminated on the film main body 51. Note that while FIG. 3 shows the printed layer 52 laminated on only one side of the film main body 51, it may be laminated on both sides. The product portion 50 includes a printed layer 52 on which, for example, information about the product to be packaged in the product portion 50 is printed. The film selvages 2, 2 include a printed layer 52 on which, for example, information for checking the printing status of the product portion 50 is printed.

[0035] Although not limited thereto, the product film 5, and the product portion 50 and film edge portions 2, 2 cut out from the product film 5 are, for example, heat-shrinkable films before heat shrinkage. The product film 5, product portion 50, and film edge portions 2 are, for example, uniaxially stretched films that heat shrink mainly in the TD (width direction) so that the product portion 50 can be used as a tubular label. The heat shrinkage rate in the main shrinkage direction of the product film 5, product portion 50, and film edge portions 2 is appropriately selected taking into consideration the ease of attachment to a container or the like when the product portion 50 is used as a label, and is preferably 30% or more, and more preferably 50% or more, when immersed in 90°C hot water for 10 seconds.

[0036] The first resin layer 11 may contain virgin resin raw materials and / or chemically recycled raw materials in addition to the recycled resin raw materials 3. The types of resins contained in the recycled resin raw materials 3 and the virgin resin raw materials in the first resin layer 11 are preferably the same, but may be different. Similarly, the types of resins contained in the recycled resin raw materials 3 and the chemically recycled raw materials in the first resin layer 11 are preferably the same, but may be different. The proportion of the recycled resin raw materials 3 relative to the total amount of virgin resin raw materials and chemically recycled raw materials contained in the first resin layer 11 (when only one of the virgin resin raw materials and the chemically recycled raw materials is contained, the total amount of either raw material) is preferably 30 wt% or less, more preferably 15 wt% or less, even more preferably 10 wt% or less, and even more preferably 5 wt% or less. However, if the resin molded product 2 is subjected to a deinking process to remove some of the printed layer when producing the recycled resin raw materials 3, the proportion is preferably 5 wt% or more, and more preferably 10 wt% or more.

[0037] The second resin layer 12 and the third resin layer 13 each preferably contain at least one of virgin resin raw materials and recycled resin raw materials, and may further contain biomass raw materials. The recycled resin raw materials contained in the second resin layer 12 and / or the third resin layer 13, like the recycled resin raw material 3, may be derived from a resin molded product 2 having a printed layer as a starting material, or from a resin molded product without a printed layer as a starting material, and may or may not contain printing-derived components. The recycled resin raw materials contained in the second resin layer 12 and / or the third resin layer 13 may be mechanically recycled products or material recycled products, but are preferably chemically recycled products. Furthermore, when the second resin layer 12 and / or the third resin layer 13 contain both virgin resin raw materials and recycled resin raw materials, the types of resins in both raw materials are preferably the same, but may be different.

[0038] The inventors discovered through experiments in the examples described below that when a multilayer recycled film is produced using recycled resin materials, the adhesive strength (interlayer strength) between a layer containing recycled resin materials and an adjacent layer in the recycled film can decrease. Decreased interlayer strength can lead to increased interlayer peeling. Further investigation by the inventors suggests that this phenomenon occurs because printing-derived components present at the interface between layers weaken the adhesive strength between the layers, causing interfacial failure. In other words, the decrease in interlayer strength is thought to be due to the printing-derived components contained in the recycled resin materials. Furthermore, the inventors also discovered that even within the same recycled film, interlayer strength varies depending on the location. This is thought to be because printing-derived components are scattered at the interface between layers, ensuring interlayer strength in areas with little printing-derived components, but decreasing interlayer strength in areas with a large amount of printing-derived components.

[0039] A decrease in the interlayer strength of the recycled film 1 is undesirable because it may make interlayer peeling more likely to occur. Therefore, the average interlayer strength between the first resin layer 11 and the second resin layer 12 is preferably 0.55 N / 10 mm or more, more preferably 0.6 N / 10 mm or more. Similarly, the average interlayer strength between the first resin layer 11 and the third resin layer 13 is preferably 0.55 N / 10 mm or more, more preferably 0.6 N / 10 mm or more. Note that the average interlayer strength may be different between the main shrinkage direction and the direction perpendicular thereto. Therefore, the smaller of the average interlayer strength in the main shrinkage direction and the average interlayer strength in the direction perpendicular thereto is preferably 0.55 N / 10 mm or more, more preferably 0.6 N / 10 mm or more.

[0040] The interlaminar strength of a film can be measured by the method described in the following examples. The average interlaminar strength is the average value of the measured values ​​obtained by measuring the interlaminar strength multiple times using multiple samples cut out from the same film. Although the interlaminar strength value varies depending on the location from which the sample is cut, the average value converges to a single value as the number of measurements increases. The average interlaminar strength here refers to such a converged value, and can be the average value of at least four, preferably 10 or more, measurements of the interlaminar strength.

[0041] Furthermore, through experiments according to the examples described below, the inventors have further discovered that a decrease in the total light transmittance at a measurement wavelength of 400 nm improves the interlayer strength of the recycled film. From this perspective, the total light transmittance of the recycled film 1 at a measurement wavelength of 400 nm is preferably less than 85%. The total light transmittance here can be measured by spectrophotometric measurement in accordance with JIS K0115. The measurement wavelength of 400 nm is the wavelength at the boundary between the visible light region and the ultraviolet light region. Therefore, even if the total light transmittance at a measurement wavelength of 400 nm is less than 85%, the transparency of the appearance of the recycled film 1 is not particularly impaired.

[0042] From the viewpoint of reducing the total light transmittance at a measurement wavelength of 400 nm, the recycled film 1 preferably contains an ultraviolet absorber. The ultraviolet absorber is preferably added to the layer containing the recycled resin raw material 3 containing the printing-derived component (in this embodiment, the first resin layer 11). The layer containing the recycled resin raw material 3 containing the printing-derived component (in this embodiment, the first resin layer 11) preferably contains 0.05% or more of the ultraviolet absorber by weight, more preferably 0.08% or more, even more preferably 0.10% or more, and even more preferably 0.20% or more.

[0043] Preferred examples of the ultraviolet absorber contained in the recycled film 1 include at least one ultraviolet absorber selected from the group consisting of benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzoxazinone-based ultraviolet absorbers, and benzophenone-based ultraviolet absorbers.

[0044] The benzotriazole-based ultraviolet absorber preferably includes 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α'-dimethylbenzyl)phenyl]benzotriazole, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4-methylphenol, 2-(2H-benzotriazol-2-yl) 4,6-di-t-butylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-t-amylphenol, 2-(2H-benzotriazol-2-yl)-4-t-butylphenol, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole (UV326), 2-(2'-hydroxy-3',5-di-t-butylphenyl)-5-chlorobenzotriazole, 6-(2-benzotriazolyl)-4-t-octyl-6'-t-butyl-4'-methyl-2,3-methylenebisphenol, and the like can be used. As the benzotriazole-based ultraviolet absorber, commercially available products can be used, such as Adekastab LA-36 (manufactured by ADEKA), Tinuvin 329 (manufactured by BASF Japan), Tinuvin 234 (manufactured by BASF Japan), Tinuvin P (manufactured by BASF Japan), Tinuvin 360 (manufactured by BASF Japan), Tinuvin 326 (manufactured by BASF Japan), Tinuvin 970 (manufactured by BASF Japan), KEMISORB 71 (manufactured by Chemipro Chemicals), KEMISORB 73 (manufactured by Chemipro Chemicals), and KEMISORB 279 (manufactured by Chemipro Chemicals). In particular, Tinuvin 326 (manufactured by BASF Japan) and Tinuvin 970 (manufactured by BASF Japan), which have absorption ability in the long wavelength region, are preferred.

[0045] As the triazine-based ultraviolet absorber, 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyl)oxyphenol or the like can be preferably used. As the triazine-based ultraviolet absorber, commercially available products can be used, such as KEMISORB 102 (manufactured by Chemipro Chemicals) and Tinosorb S (manufactured by BASF Japan).

[0046] As the benzoxazinone-based ultraviolet absorber, preferably, 2,2'-p-phenylenebis(3,1-oxazin-4-one), 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2-(2-naphthyl)-3,1-benzoxazin-4-one, 2,2'-p-phenylenebis(3,1-benzoxazin-4-one), 2,2'-(2,6-naphthylene)bis(3,1-benzoxazin-4-one), etc. can be used. As the benzoxazinone-based ultraviolet absorber, commercially available products can be used, for example, KEMISORB 500 (manufactured by Chemipro Chemical Co., Ltd.).

[0047] As the benzophenone-based ultraviolet absorber, preferably, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 3,5-di-t-butyl-4-hydroxybenzoic acid, n-hexadecyl ester, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 1,4-bis(4-benzoyl-3-hydroxyphenoxy)butane, 1,6-bis(4-benzoyl-3-hydroxyphenoxy)hexane, etc. can be used. As the benzophenone-based ultraviolet absorber, commercially available products can be used, such as KEMISORB 11 (manufactured by Chemipro Chemicals), KEMISORB 12 (manufactured by Chemipro Chemicals), KEMISORB 111 (manufactured by Chemipro Chemicals), and KEMISORB 11S (manufactured by Chemipro Chemicals).

[0048] In addition, it is also possible to use a hindered amine light stabilizer in combination with the various ultraviolet absorbers described above. Among the hindered amine light stabilizers, representative commercially available examples include Tinuvin 123, Tinuvin 152, Tinuvin NOR 371 FF, Tinuvin XT850 FF, Tinuvin XT855 FF, TINUVIN 5100, TINUVIN 622SF, Flamestat NOR 116 FF manufactured by BASF Japan, and Adekastab LA-81 manufactured by ADEKA. These may be used alone or in combination of two or more.

[0049] [2. Manufacturing method of recycled film] Fig. 4 is a diagram schematically illustrating a resource circulation system S1 for producing a recycled film 1. As shown in Fig. 4, in the resource circulation system S1, a resin molded product 2 is recycled and a recycled film 1 is produced as a new film.

[0050] The resource circulation system S1 includes a manufacturing apparatus 20 for a recycled resin raw material 3 and a film manufacturing apparatus 30. In the resource circulation system S1, the manufacturing apparatus 20 is used to manufacture the recycled resin raw material 3 from a resin molded product 2. The manufacturing apparatus 20 is an apparatus for manufacturing the recycled resin raw material 3 using the resin molded product 2 as a starting material. The recycled resin raw material 3 is a resin raw material obtained by processing the resin molded product 2 into a shape that is easy to handle when manufacturing a recycled film 1 from the resin molded product 2. Specifically, the recycled resin raw material 3 can be in the form of fluff 3a, pellets 3b, powder 3c, granulated material 3d, or the like. Some pellets 3b are manufactured by heating and melting the raw material and then solidifying it. However, unlike such pellets 3b, granulated material 3d is a mass obtained by compressing and solidifying powdered raw material without heating and melting it. The granulated material 3d is typically an opaque mass. In addition, recycled resin raw materials 3 that are produced without heating and melting the raw materials, such as fluff 3a, powder 3c, or granules 3d, can be more susceptible to thermal degradation than recycled resin raw materials 3 that are produced by heating and melting the raw materials and then solidifying them, such as the above-mentioned type of pellets 3b, because they do not undergo excessive thermal history such as heating and melting during processing.

[0051] The resin molded product 2 can be processed into fluff 3a by, for example, appropriately using a known crusher, shredder, cutter, etc., to break the resin molded product 2 into small pieces. The size (area) of the fluff 3a is 500 mm 2 Less than 300mm is preferable 2 Less than 200mm is preferable 2 Less than 100mm is more preferable 2 The following are particularly preferred:

[0052] The resin molded product 2 can be processed into pellets 3b using, for example, a known resin pellet manufacturing machine. For example, fluff 3a is supplied to an extruder, heated and melted in the extruder, extruded through a die, and the extruded material is cut into an appropriate shape to produce pellets 3b. Note that pellets 3b may be produced using not only the resin molded product 2 (fluff 3a) but also virgin resin raw materials and / or chemically recycled raw materials. In this case, virgin resin raw materials and / or chemically recycled raw materials are supplied to the extruder in addition to fluff 3a. This method produces pellets 3b of the type produced by heating and melting raw materials and then solidifying them.

[0053] Another type of processing method for pellets 3b is, for example, the following method: The film edge 2 is unwound from a roll, and one film edge 2 or a bundle of film edges 2 is twisted by rotating it parallel to the conveying direction, and the twisted film edge 2 is compressed and then cut to a predetermined size. In this method, pellets 3b are produced without heating and melting the raw material.

[0054] The resin molded product 2 can be processed into powder 3c, for example, by the following method. First, the fluff 3a is immersed in an appropriate solvent, and the resin component contained in the fluff 3a is dissolved in the solvent to produce a solution containing the resin component. Then, the resin component is precipitated by cooling the solution, mixing a poor solvent into the solution, and / or heating the solution to evaporate the solvent. Thereafter, the precipitate of the resin component is dried to produce powder 3c.

[0055] The resin molded product 2 can be processed into the granules 3d, for example, by drying the above-mentioned resin component precipitate while stirring it under vacuum. Alternatively, the granules 3d can be produced using a known granulator. In this case, the above-mentioned resin component precipitate or powder 3c can be introduced into the granulator. In this case, it is preferable to dry the resin component precipitate or powder 3c before or during granulation, or to dry the granules 3d after granulation.

[0056] In producing the recycled resin raw material 3, the printed layer contained in the resin molded product 2 may be removed to some extent by a known deinking method. That is, the recycled resin raw material 3 may be produced from a resin molded product 2 in a state in which part of the printed layer has been removed and part remains. One example of a deinking method is to immerse the resin molded product 2 in a cleaning solution containing a solvent capable of dissolving the printed layer. Alternatively, the printed layer may be physically removed from the resin molded product 2 using a blade, abrasive roller, file, metal rotating brush, rotary blade, scraper, belt sander, blasting device (including wet blasting device), or the like.

[0057] In the resource circulation system S1, a film manufacturing apparatus 30 is used to further manufacture a recycled film 1 from the recycled resin raw material 3. The film manufacturing apparatus 30 is an apparatus that manufactures a recycled film 1 using the recycled resin raw material 3 manufactured using the manufacturing apparatus 20. A known film formation method can be used as a processing method for the recycled film 1.

[0058] FIG. 5 shows an example of the configuration of a film manufacturing apparatus 30. In the example of FIG. 5, the film manufacturing apparatus 30 includes a T-die 300, cast rolls 310 and 320, a longitudinal stretching machine 41, and a transverse stretching machine 42. The T-die 300 includes a T-die main body 301 and raw material input sections 330, 331, and 332. The raw material for the second resin layer 12, which is one of the surface layers, is input into the raw material input section 330. The raw material for the third resin layer 13, which is the other surface layer, is input into the raw material input section 332. The recycled resin raw material 3, which is the raw material for the first resin layer 11, which is the intermediate layer, and other raw materials, such as virgin resin raw materials and chemically recycled raw materials, if any, are input into the raw material input section 331. If an adhesive layer is inserted between the first resin layer 11 and the second resin layer 12 and / or between the first resin layer 11 and the third resin layer 13, a separate raw material inlet for the adhesive layer is provided, into which the raw material for the adhesive layer is introduced. The T-die body 301 heats and melts the raw materials supplied via the raw material inlets 330, 331, and 332 (and the raw material inlet for the adhesive layer, if any), and then co-extrudes them to fuse the molten materials introduced into each raw material inlet to form a single integrated recycled film 1 (molten material). The casting rolls 310 and 320 cool the extruded molten material and send it downstream.

[0059] The recycled film 1 is then appropriately stretched to impart heat shrinkability and processed into a heat-shrinkable film. The longitudinal stretching machine 41 stretches the recycled film 1 cooled by the cast rolls 310 and 320 in the MD at a predetermined stretch ratio. The transverse stretching machine 42 stretches the recycled film 1 that has been stretched in the MD at a predetermined stretch ratio in the TD. The recycled film 1 that has been stretched in various ways is wound into a film roll.

[0060] Thereafter, a functional layer may be appropriately laminated on the recycled film 1. Examples of the functional layer include a printing layer, a matte layer, a protective layer (e.g., an overcoat layer, a hard coat layer, etc.), a slippery layer (e.g., an inner coat layer, an antiblocking layer, etc.), a barrier layer, a light-shielding layer, an ultraviolet absorbing layer, a metal film, an easy-adhesion layer, a release layer, an antistatic layer, and a conductive layer.

[0061] [3. Features] The recycled film 1 is manufactured using recycled resin raw material 3, which contributes to resource circulation. Although the recycled film 1 contains printing-derived components that cause a decrease in interlayer strength, the total light transmittance at a measurement wavelength of 400 nm is adjusted to less than 85%. As a result, a certain level of interlayer strength is ensured, and the recycled film 1 is provided that is resistant to layer peeling.

[0062] [4. Modifications] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be combined as appropriate.

[0063] [4-1] In the above embodiment, the first resin layer 11 is configured to contain the recycled resin raw material 3. However, the first resin layer 11, which is the intermediate layer, may not contain the recycled resin raw material 3, and at least one of the second resin layer 12 and the third resin layer 13, which are the surface layers, may contain the recycled resin raw material 3. Alternatively, all of the first resin layer 11, the second resin layer 12, and the third resin layer 13 may be configured to contain the recycled resin raw material 3.

[0064] [4-2] In the above embodiment, the recycled film 1 has a three-layer structure, but it may have a two-layer structure or a multi-layer structure of four or more layers. In this case, at least one of the layers contains the recycled resin raw material 3. [Example]

[0065] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0066] Films according to Reference Examples shown in Tables 1 and 2, and recycled films according to Examples 1 to 5 and Comparative Examples were produced. All of these films had a three-layer structure, with surface layers (second and third resin layers) formed on both sides of an intermediate layer (first resin layer). The intermediate layer and both surface layers were bonded together with adhesive layers primarily composed of polyester-based elastomer. The thickness of all of these films was approximately 30 μm. More specifically, the thickness of the intermediate layer was approximately 18 μm, the thickness of each surface layer was approximately 6 μm, and the thickness of each adhesive layer was approximately 0.5 μm. All of these films were uniaxially stretched heat-shrinkable films with the TD as the main shrinkage direction. For all of these films, the raw materials for each layer shown in Tables 1 and 2 were fed into an extruder with a barrel temperature of 160°C to 200°C in the weight ratios shown in Tables 1 and 2, co-extruded through a multi-layer die at 200°C, and cooled and solidified using a cast roll at 50°C. Next, the film was stretched in the MD at a stretching ratio of 1.4 times using a longitudinal stretching machine with a preheating roll set to 85°C and a stretching roll set to 90°C, and then stretched in the TD at a stretching ratio of 4 times in a tenter stretching machine (transverse stretching machine) including a preheating zone at 102°C, a stretching zone at 89°C to 91°C, and a heat-setting zone at 86°C, and then taken up on a winder to produce a film.

[0067] [Table 1]

[0068] [Table 2]

[0069] In Tables 1 and 2, "polyester-based resin" refers to virgin polyethylene terephthalate material, and "polystyrene-based resin" refers to virgin styrene-butadiene copolymer material. Furthermore, "recycled resin material" in Tables 1 and 2 refers to pellets produced from the same film edge as film edge 2 described in the above embodiment. These pellets were produced by crushing the film edge without deinking to obtain fluff, then mixing this fluff with virgin styrene-butadiene copolymer material in a ratio of 1:9 and heating and melting the mixture. The film body of this film edge was a three-layer film having a middle layer made of polystyrene-based resin and surface layers made of polyester-based resin arranged on both sides of the middle layer. More specifically, the polyester-based resin contained in both surface layers was a polyester-based resin composed of a dicarboxylic acid component and a diol component, and the polystyrene-based resin contained in the middle layer was a styrene-butadiene copolymer. The printing area of ​​this film edge was 10%. In this film edge, the thickness of the surface layer:thickness of the middle layer:thickness of the surface layer=1:3:1.

[0070] In each of the films according to the Reference Example, Examples 1 to 5, and Comparative Example, the type of ultraviolet absorber shown in Tables 1 and 2 was mixed into the intermediate layer in the amount (weight ratio) shown in Tables 1 and 2. The amount added here is the amount added (weight ratio) relative to the entire intermediate layer.

[0071] For each of the films according to the Reference Example, Examples 1 to 5, and Comparative Example, the total light transmittance at a measurement wavelength of 400 nm, the heat shrinkage in MD and TD, and the average interlayer strength in MD and TD were measured. The results are shown in Tables 1 and 2. The measurement methods for these indices are as described below.

[0072] <Method for measuring total light transmittance at a wavelength of 400 nm> The total light transmittance was measured by spectrophotometric measurement in accordance with JIS K 0115. More specifically, the light transmittance was measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation, Model V-670) by changing the measurement wavelength from 800 nm to 300 nm at a scan speed of 100 nm / min in 1 nm intervals.

[0073] <Method for measuring heat shrinkage> Samples measuring 100 mm in length (MD) x 100 mm in width (TD) were cut out from each of the films according to the Reference Example, Examples 1 to 5, and Comparative Example. Each sample was immersed in warm water at 70°C, 80°C, and hot water at 98°C for 10 seconds, and then removed. The MD heat shrinkage was calculated according to the following formula (1), and the TD heat shrinkage was calculated according to the following formula (2). In formula (1), LMD is the MD length (mm) of the sample after heat shrinkage, and LTD in formula (2) is the TD length (mm) of the sample after heat shrinkage. The heat shrinkage was measured using three samples, and the average value was calculated. Heat shrinkage rate (%) = {(100 - LMD) / 100} × 100 (1) Heat shrinkage rate (%) = {(100 - LTD) / 100} × 100 (2)

[0074] <Method for measuring average interlaminar strength> The interlaminar strengths in the main shrinkage direction (TD) and the direction perpendicular thereto (MD) were measured using a method in accordance with JIS K6854. First, a sample measuring 100 mm in length (MD) × 10 mm ± 0.5 mm in width (TD) was cut out from each film according to the Reference Example, Examples 1 to 5, and Comparative Example. A portion of the edge of each sample was subjected to MD interlaminar peeling between the middle layer and one of the surface layers. Then, using a peel tester (Shinto Scientific, Model No. HEIDON TYPE: 17 Peel Strength Tester), the sample was pulled in the MD at a pulling rate of 200 mm / min, and the strength (N / 10 mm) at room temperature (23°C) when peeled in a 180° direction was measured, and this was defined as the MD interlaminar strength. Similar measurements were performed 10 times on 10 samples, and the average value was defined as the average MD interlaminar strength. Furthermore, samples measuring 100 mm in width (TD) × 10 mm ± 0.5 mm in length (MD) were cut out from each film of the Reference Example, Examples 1 to 5, and Comparative Example, and the average interlaminar strength in TD was determined in the same manner as in MD. The evaluation criteria were as follows: an average interlaminar strength of 0.55 N / 10 mm or more was rated as "good (◯)", and an average interlaminar strength of less than 0.55 N / 10 mm was rated as "poor (×)".

[0075] <Consideration> As can be seen from a comparison between the Reference Example and the Comparative Example, when a multilayer film is manufactured using recycled resin raw materials (i.e., when the film contains printing-derived components), the interlayer strength of the film decreases (the Reference Example and the Comparative Example differ only in the content of recycled resin raw materials, but the average interlayer strength in MD of the Reference Example is 0.6 N / 10 mm, while the average interlayer strength in MD of the Comparative Example is reduced to 0.5 N / 10 mm. A similar trend is observed for the average interlayer strength in TD). That the inclusion of recycled resin raw materials can reduce interlayer strength can also be seen from a comparison between Examples 1 and 2, which are manufactured under the same conditions except for the content of recycled resin raw materials.

[0076] However, as can be seen by further comparing the Comparative Example with Example 1, adding an ultraviolet absorber and reducing the total light transmittance at 400 nm improves the interlayer strength of the film (the Comparative Example and Example 1 differ only in the amount of ultraviolet absorber added and the total light transmittance at 400 nm, but the average MD interlayer strength of the Comparative Example is 0.5 N / 10 mm, while the average MD interlayer strength of Example 1 is improved to 0.7 N / 10 mm. A similar tendency is confirmed for the average TD interlayer strength). The fact that the interlayer strength improves when the total light transmittance is reduced can also be roughly understood by comparing Examples 2 to 4, which are produced under the same manufacturing conditions except for the amount of ultraviolet absorber added and the total light transmittance at 400 nm.

[0077] Furthermore, when Example 2 and Example 5 are compared, which are produced under the same manufacturing conditions (same amount of UV absorber added) except for the type of UV absorber, the interlayer strength (MD) is improved in Example 5, which has a lower total light transmittance at 400 nm than Example 2. This also shows that lowering the total light transmittance improves the interlayer strength of the film.

[0078] It was also confirmed that the content of recycled resin raw materials, the amount of UV absorber added, and the total light transmittance at 400 nm did not have any particular effect on the thermal shrinkage behavior of the film. [Explanation of symbols]

[0079] 1. Recycled film 11 First resin layer 12 Second resin layer 13 Third resin layer 2. Resin molding (film edge) 5 Product Film 50 Product Department 51 Film body 52 Printing layer 3 Recycled resin raw materials 3a Fluff 3b Pellets 3c powder 3d granules 20. Recycled resin raw material manufacturing equipment 30 Film manufacturing equipment 300 T-die 301 T-die body 310,320 Cast Roll 330,331,332 Raw material input section 41 Longitudinal stretching machine 42 Lateral stretching machine S1 Resource Recycling System

Claims

1. a first resin layer; a second resin layer laminated on one surface of the first resin layer; Equipped with the first resin layer contains a recycled resin material made from a resin molded product having a printed layer and an ultraviolet absorber; The total light transmittance at a measurement wavelength of 400 nm measured by spectrophotometric measurement in accordance with JIS K0115 is less than 85%; The average interlayer strength between the first resin layer and the second resin layer is 0.55 N / 10 mm or more. Recycled film.

2. The first resin layer contains the ultraviolet absorber in a weight percentage of 0.05% or more. The recycled film according to claim 1.

3. The resin molded product contains at least one of a polystyrene-based resin, a polyester-based resin, a polyolefin-based resin, and a polyamide-based resin. The recycled film according to claim 1 or 2.

4. It is a heat-shrinkable film. The recycled film according to claim 1 or 2.

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